Australia 85c South Africa 80c New Zealand 95c Malaysia 52.

25

PRACTICAL

OCTOBER 1978 45p

duel

PRACTICAL
LE CTRONI
F on
Road
with 8 Beyhem Kent
in association evenoake
ics rt Clicept Electronics $

lila SYSTEM
s issue
60p
Is
 to
of easy for

Teleply
library garnes
A whole cartridge to enjoy
assembleall the familyworks
- TV

now praesents you andfull colour

- all in
OK on Black
- willlong
the
save
and White ir
you pounds
run.

COLOURCART
FFIEE
STAR*OFFERS cri

WITH
of a Professional
Football,
a Kit
consistingof 10 games- are
at -- consists All .holes kit!
be snuffed on which
Mains.Adaptor. enjoyable
that cannot cartridge etc. this superbly
of a bargain
*one - Shoot
Controls(1 & 2 players), to assemble
consists it is
We offer ou
Hand
OFFER *Joystick Basketball how easy
Box - Hockey, be surprised ONLY
all
Our INTRODUCTORY
Inject
Moulded 2 players), You'll
(1 required.
Finished Squash equipment
Solo
Tennis, No Special
-drilled -
pre

will
game
NEVV
months la and those
Every
3 to you include
available
become production Out
under VVar,VVipe
already Space of these
price Fully
Submaries,more. The £19 depending Cartridge
Assembled
many £12 to Add
and
Will vary
from of the game.
include: Controls - 04.90 £3.00
complexity available E.12.90
the Hand kit
upon
Cartridges
NOW
-
and
Cartridge Controls
- £18.90 With basic
4 games Hand already
Additional
Cycle -- and Controls
Stunt Battle -- Cartridge Cartridge
2 games
Race
Road
this Pagnevv
Watch tor
each
month as they
artridges, with printed
available. cmpldeteeasy to
follovv
become come casoe an
Cartridges
assemb.
ly instructions

Electrical knowledge is not a necessity to assemble this project - just simple soldering.
Cheques and Postal Orders to be made payable to TELEPLAY: send your order (No Stamp Needed) to
Teleplay, Freepost, Barnet, EN5 2BR or telephone your order quoting your Barclaycard or Access number.
Queries and Technical Advice offered either by phone or by calling at our shop.
BARCLAYCARD
SHOP OPEN -10am to 7pm - Monday to Saturday AIL
CLOSE TO NEW BARNET BR STATION - MOORGATE LINE winos? Amr.

rif 1
All parts fully guaranteed.
EUROPE'S LARGEST STOCKIST OF TV GAME COMPONENTS.

14 Station Road, New Barnet, Herts EN5 1QW Tel: 01-440 7033/01-441 2922
PRACTICAL
ELECTRONICS
VOLUME 14 No.14 OCTOBER 1978

CONSTRUCTIONAL PROJECTS
P.E. V.D.U. SYSTEM -1 by A. A. Berk, B.Sc., Ph.D.
Up to date "one chip" memory mapped system 1054
FUEL CONSUMPTION METER By J. McCarthy
An aid to economy, suitable for most cars 1060
HIGH PERFORMANCE POWER SUPPLY UNIT by R. Lawrence, B.Sc.
Voltage control down to zero, plus current limiting 1070
ANALOGUE COMPUTER -2 by P. J. Kronis, B.Sc.
Construction details 1074
TWO RANGE TIMER by J. D. Jardine
A portable, inexpensive general purpose unit 1088

GENERAL FEATURES
IMPEDANCE by Toby Bailey and Bob Whitaker
Do you understand it? 1066
MICROBUS by D.J.D.
A bi-monthly focus on micro's for the home constructor 1098
INGENUITY UNLIMITED
Capacitor Continuity Tester-Synthesiser Repetitive Waveform Generator
Simple Fuzz-Accenting Metronome-Stereo Indicator
External Input Unit for Synthesisers 1080

NEWS AND COMMENT

EDITORIAL 1049
MARKET PLACE
New products 1050
SPACEWATCH by Frank W. Hyde
Pluto, More from the USSR, Copernicus discovers Black Hole 1053
POINTS ARISING
Linear Capacitance Meter, Dimwit, Kiln Controller 1058
BOOK REVIEWS 1084
NEWS BRIEFS
Strain Gauge-Big Brother Check-Micro Power Pack-Computers Galore Club 1087
Underground Cameras-Steam Advice-Here's To Progress 1090
Teletext Course 1094
Disc Full of Holes 1102
HOW TO USE YOUR FREE STICKIES 1093
INDUSTRY NOTEBOOK by Nexus
What's happening inside industry 1097
PATENTS REVIEW
Thought provoking ideas on file at the British Patents Office 1100
READOUT
A selection of readers' letters 1102

Our November issue will be on sale Friday, 13 October 1978, price 50p
(for details of contents see page 1059)

c IPC Magazines Limited 1978. Copyright in all drawings, photographs and articles published in PRACTICAL
ELECTRONICS is fully protected, and reproduction or imitations in whole or part are expressly forbidden. All
reasonable precautions are taken by PRACTICAL ELECTRONICS to ensure that the advice and data given to
readers are reliable. We cannot, however, guarantee it, and we cannot accept legal responsibility for it. Prices
quoted are those current as we go to press.

Practical Electronics October 1978 1033

 MINI CONSOLES Stop wasting time soldering SC BOXES
Ideal for small desk control The NEW MW BREADBOARD accepts
Easily drilled or punched,
panels and consoles. Transistors, LED's,Diodes, Resistors, Capacitors orange, blue, black and grey
Moulded in orange, blue, and all DIL packages with 6 to 40 pins
ABS. Incorporate slots for
black and grey ABS. holding 1.5mm thick pcb's.
Incorporates slots for holding Aluminium panel sits recessed
1.5mm thick pcb's into front of the box and
Aluminium panel sits recessed into front of console held by screws running into
and held by screws running into integral brass bushes. integral brass bushes.
MC 161 x 96 x 58mm £2.12 11-91 (Includes VAT) SC 85 x 56 x 35mm 97p (1.9) (Includes VATI
MC 215 x 130 x 75mm £2.94 (1-9) (Includes VAT) SC 111 x 71 x 48mm £1.29 (1-9) (Includes VAT)
(Prices include VAT ,k P.P.) SC 161 x 96 x 59mm E1.81 (1-9) (Includes VAT)
Add 25p per £1 order value for Post & Packing
ECONOMY QUALITY LED's Includes slot -in Component Support Bracket and has
470 individual sockets, plus Vcc and Ground Bus Strips
50 for only £5 - 100 for only £9 Price £9.72 (includes VAT & P,P.1
Mixed bags, all sizes, various colours
240 VOLTS MINI HAND DRILLS
Ideal for drilling pcb's, chassis
TYPE MP NEON INDICATOR
125
lens
411) 16"" 41115
lens Supplied with resistor for 24.0 Volts operation
etc as well as model making.
Supplied with 3 collets that
150mm leads, held in 6.4mm hole by nut accept tools and drills with
Full specification LED's also available 1mm, 2mm and 1/8" dia
Red (specify size) 75p per pack shanks.
Green, Yellow, Orange (specify size) £1.20 per pack E9.72 (includes VAT & P.P.)
Packs contain 5 LED's, mounting clips and data Red, Amber, Clear, Opal 20p each Accessory tools... 5 Burrs, 1mm, 2mm, 1/8th Drills,
3/32" Collet Price £1.75 (Includes VAT & P.P.)
TYPE A NEON INDICATORS SEVEN SEGMENT DISPLAYS
RC BOXES ABS and DIECAST
Supplied with resistor for 240 Volts operation Economy quality 1.5mm pcb slots and close
Held in 8mm hole by plastic bezel Red, yellow and green fitting flanged lids. ABS in
150mm wire leads Only 45p each
orange, blue, black or grey
Common Anode -0.3',-Left Decimal

AA
tl 1
AG AH
Full specification displays
also available as above
Red @ 98p each
colours. Diecast in natural
or grey hammertone colour.
Lid held by screws running
into integral brass bushes.
Red, Amber, Clear, Opal 19p each Green and Yellow @ £1.35 each.
Green 28p each Data supplied with full spec. ABS Natural Hammertone
Diecast Diecast
displays only.
RC 100x62x25mm 68p 70p 93p
12 VOLTS MINI HAND DRILL RC 112x62x31mm 79p 94p 1.23
Quantity quotations on request RC 120x65x40mm
Ideal for drilling pcb, chassis 88p 1.22 1.59
etc as well as model making. P.P. Note Unless included in price add 25p Post & Packing RC 150 x 80 x 50mm 1.03 1.64 2.11
Supplied with 2 collets that for orders totalling under £10. All prices include VAT and RC 190x 110x6Omm 1.77 2.533.08
accept tools and drills with are valid in UK only for 2 months from journal issue date Polystyrene version
3/32" and 0.50" dia shanks. in grey only, no slots, no integral brass bushes
£7.56 (Includes VAT & P.P.) RC(P) 112 x 61 x 31mm 61p
Michael Williams Electronics All prices are 1-9 off, include VAT, but please add
I 47 Vicarage Av. Cheadle Hulme, Cheshire SK8 25p per £1 order value for Post & Packing
1/4

AS prices include VAT. Add 25p

AT LAST! Uf(l'envi AST RA -p AK

92 GODSTONE ROAD
for P&P (Extra for overseas).
Discounts over E 10 less 5%, over
f20 less 10%. over E50 less 15%,
over (100 less 20%.
Send SAE for complete list of

SEEMET
THE FAMOUS POCKETSIZE
WHYTELEAFE SURREY CR3 OEB
7400 end 74LS Series TR

7400
7401
7402
740
0.12
0.12
012
74100
021
0.21
0.21
1486
74088
7489
7490
740
028
1.50
200
0.35
74100
0.31 74168
74169
14170
74172
components
740

ill
400
14180
2.10
2.10
114
UNEANS
CA3045

11438014
14138114
-14
-14
-14
-14
0.45CA3046

0.71
812
121
METAL DETECTOR 7403
7404
0.12
0.13
0.21
0.21
7491
7492
0.05
0.44
0115

0.82
74173
14174
I"
Oil 113
112
1.4171011
LAPIIN -14
MC131W -14
-14 0.32
0.32
1.50
1405 0.13 0.21 7493 0.46 0.95 74175 OH 1.12
Seemet.readily detects concealed 7406 0.28 7494 010 740175 325
NE555N
NE5580 -14
-8 0.30
0.65
74178
ferrous and non-ferrous metals within 7407
7408
0.28
0.14 0.21
7495
7496
0.54
0.60
1.06
1.30 74177
0.80
OM
NE25016 -14
0117270214
310
0.50
range of its detector field. Ideal for 74008
7409
040
014 0.21
7497
74100
2.00
014
74178
74179
120
1.10
50751100 0.10
007130030 1.15
finding concealed pipes, wires, nails 7410
7411
013
0.18
0.22
0.21
74104
74105
0.48
0.40
74180
74181
040
1.75 338
50760130 1.35
00700230 1.35
etc. One -handed operation, uses 7412
7413
0.21
0.25
0.21
0.48
74107
74109
0.28
0.45
0.40
0.40
74182 0.75
745182 2.30
007803311 115
standard PP3 Battery (not supplied). 7414 064 1.05 74110 0.46 74H183 019
7065508
741613111
8.36
1.40
7415 0.21 74111 070 74184 110 17141200
741854 0.F4
ONLY f3.25 plus p. Et p. 25p. 7416 0.27 14112 0.40
74186
1.20
713413414 118
7417 0.27 74113 030 0.40 7.20
(inc. VAT), full instructions supplied. 7420 0.13 021 74114 0.40 74188
74189
2.70
3.50
TBA800
11.4810S
035
1.04
7421 0.24 0.21 74116 110
74190
TC427050 210
7422 0.17 021 74118 082 1.05 0.10
TC142020 324
UNBEATABLE 7423
7425
025
0.20
74119
74120
1.26
0.82
74191
74192
0.09
0.99
0.96
1.40
28414 1.80

DIMMER OFFER 7426

7427
025
025
0.26
030
74121
74122
0.25
0.40
74193
74194
1.06
0.00
1.50
200
op Amps
03130 -T099 1.04
7428 034 0.34 74123 0.50 0.51 74195 014 1.40
from Britain's largest Dimmer Makers. 7430 013 0.21 74124 1.25 74196 0.90 1.15
1313014
1313014
-8 039
-T099 0.41
74030 0.30 74125 0.40 0.48 14197
DU "5 L54348N -14 1.00
Complete Kit of Parts for our 7432
7437
0.24
0.24
0.31
0.21
74126
74128
0.45
002
0.41 74198
74199
1.41
1.41
LM709 -8 0.40
LM709 -14 0.42
VCL 500M, 500W Dimmer Switch. 7438
7440
0.24
0.13
0.21
0.22
74132
74134
On
0.31
0112 74221
74247
1.50 1.06
010
LM709 1099 5.511
1.51741 -8 0.22
Only f2.00, plus p. Et p. 25p. 7441 0.52 74135 Oil 74248 0.55 114741 -14 520
7442 045 010 74136 055 0.40 74249 CH 04741 -T099 5.45
(inc. VAT) full instructions supplied. 7443 090 74137
74138
0.04
0.12
74251
74253
1.00 OM 1.14747 -14 0.75
7444 0.80 ,
115., 1.14390011 0.65
Send coupon below with your remittance. 7445
7448
010
0.70
74139
74141 0.61
04 2 74257
74258
-2
1.15
MC1458P -8 042
7447A 0.80 0.94 74142 2.00 74260 028 VOLTAGE
Please supply - :
PE3 NAME 7448 040 0.94 74143 200 74281
325 AEGULATOGS
SEEMET KITS 7449 0.94 74144 200 74268 013
14273 2.15 108
114300 -7099 1.08
7450 013 74145 064 120
I at f3.50 p. ADDRESS 7451 0.13 0.21 74141 120 74279 126 055
1.143098 -T03 1.31
74283 1.71
134723 -14 4.44
7453 0.13 74148 1.15 1.116
DIMMER KITS 7454 0.13 0.21 74150 099 74284 5.16
7805
7812
70220 015
10220 0.115
I at £2.25 inc. of p. to P 7455 0.26 74151 010 0.90 74289 312 7015 10220 0.55
7460 0.13 74153 0.40 0.56 74290 015 7824 70220 IUD
7470 74154 100 122 74293 135 100
I enclose cheque/P.O. POSTCODE 7472
0.24
022 74155 083 0.91 74298 112 1.40
7905 70220 1.10
7912 10220 1.11
fort BLOCK CAPS PLEASE 7473
7474
0.21 0.36 74158
74157
0.63
0.83
0.90
010
74352
74353
1.00
1.05
7915 10220 HI
0.26 0.38
73074 0.50 74158 051 042 74385 052
OIL SOCKETS
7475 ins gm 74159 110 /4388 002
0.11

LL Fotherby,Willis Electronics Ltd. 7476

74713
7480
025
0.46
030
031
74160
74181
74182
0.80
010
0.10
1.30
010
1.30
74387
743613
74388
14390
0.45
052
0.50
Iii:in
16 pn
18 Mn
1.12
0.13
523
7481 0.04 74163 000 012 1112
20 pn 527
GLADSTONE TERRACE, STANNINGLEY, LEEDS, LS28 6NE. 7482 0.75 74184 Ole 1.20 74393
73670
2.00
2.30
22 pn 025
7483 0.72 01 7 74185 0.80
Telephone Leeds(STD0532)563373 Telex 557111 IGLYNWEL: 7484 0.90 74186 0.90
24 en
28 pn
S30
0.44
7485 0.00 0.97 74187 2.70 40 On 8.55
4,

1034 Practical Electronics October 1978

 NOT EVERY CABLE
HAS A LABEL
Everyone who works with electricity needs to know at
some time or other what's going on inside the cable he's
handling. What voltage. What current. What resistance.
Not knowing the answers, or worse still having
inaccurate answers, can make life difficult, even terminal.
Eagle Test Equipment gives the right answers
The range covers general multimeters, high voltage
probes, clamp meters, insulation testers.
Here are just four. Send the coupon for details of all
the rest.

KEW 7 Multimeter EM 1200 Multimeter K1400 Multimeter EM10, 20 & 30 Multimeters

1000 OPV. DC volts up to 1000, 100,000 OPV. Taut band 20,000 OPV. DC and A.: volts 10,20 & 30,000 OPV. All with antiparallax
DC amps up to 100 mA. AC movement. Overload up to 5000. DC and AC amps mirror scale. DC volts to 100011200 for
volts up to 1000. Resistance up protection. Reversible DC up to 10. Resistance up to 20 EM30). DC amps to 250 mA (600 for
to 150 Kohms. Pocket size. polarity. AC amps: 15, AC megohms. "Off" damping. EM301. AC volts to 1000 (1200 for EM30).
"Off" damping. Complete with volts to 1500. DC amps up to Overload protection. R.R.P. Resistance up to 6,5 and 60 megohms
leads & battery. R.R.P. £6.95 15, DC volts to 1500. £68.00 ex. VAT. respectively. R.R.P.'s EM10 £12.40 EM20
ex. VAT. Resistance up to 200 f16.40 EM30 £18.95 ex. VAT.
megohms. R.R.P. £49.95
ex. VAT.

Test Equipment: EAGLE oT

Please send me details of your complete range of Test Equipment.
Name Company
Address

Precision Centre, Heather Park Drive,

EAGLE INTERNATIONAL Wembley, Middlesex HAO 1SU.
PE1
dam

Practical Electronics October 1978 1035

 Yoail learn a lot from Heathkit electronics courses.
Heathkit electronics courses are a most effective way to learn-
vv
with fast, reassuring results.
Each course is a complete self -instructional package with clear, SPECIAL OFFER
concise instructions in everyday language. You follow at your own pace, 10, oh selected courses
1978
using modern teaching aids and expert guidance. until 15th October
Four basic courses to start with.
DC electronics, AC electronics, semi -conductors and electronic circuits.
These courses give you a thorough and practical understanding-the key
to all knowledge in the field of electronics.
Microprocessors and digital techniques.
The advanced Heathkit courses take you on to higher levels of
computer technology and advanced circuit design, using the
same easy -to -follow learning system.
Experimenter -Trainers.
With the benefit of increased practical guidance, these optional
aids win help you through the courses with exceptional speed.
The finest way to learn.
aloripasicas
Heathkit courses are used by home students, industrial
concerns, technical colleges and schools. They're acknowledged
as the finest way to learn. And the range of courses is complete
from the earliest stages to the most advanced steps in specialist
fields.
To Heath (Gloucester) Ltd., Dept:11On, Bristol Road, Gloucester, GL2 6EET1
Send for the Heathkit Catalogue now. Please tick the literature you want and enclose the appropriate amount in
As well as electronics courses, the Heathkit catalogue contains scores of postage stamps.
electronics kits which you can build yourself. Burglar alarms, radios, Heathkit Catalogue only (enclose 20p).
digital docks, car tune-up systems, test instruments, metal locators... I 16 page Computer Brochure only (enclose 20p).
and an exciting new range of personal computers!
Forty pages packed with exciting kits you'll be proud to make. I Name
IAddress
When you receive your catalogue you twill get details
of this free offer worth appmximately
Registered in England, number 606177
.11=11.1
Schlumberger There are Heathkit Electronics Centres at 233 Tottenham Court Road, London I
(01-636 7349) and at Bristol Road, Gloucester (Gloucester 29451).

Put a Clamp on those

small jobs with
ucro NO DEX quick -grip vice

Adaptable on all
drill supports. V -notch
allows fixing of all profiles.
Our new 1978 catalogue lists a card frame system
that's ideal for all your module projects - they
used it in the ETI System 68 Computer. And Dimensions
Overall length 150mm The patented locking system of the
we've got circuit boards, accessories, cases and Overall width 130mm Nodex vice allows for instantaneous
boxes - everything you need to give your equip- Overall height 50mm locking or loosening for use as a vice
ment the quality you demand. Send 25p to cover Jaw opening 70mm or as a press. Usable horizontally or
post and packing, and the catalogue's yours. Jaw height 35mm vertically on the bench top or on the
Jaw width 70mm bench edge.
Weight 850 grammes
Descriptive leaflet and general catalogue available from
VERO ELECTRONICS LTD. RETAIL DEPT.
Industrial Estate, Chandlers Ford, Hants. SO5 3ZR SPECIAL PRODUCTS DISTRIBUTORS LTD.
Telephone Chandlers Ford (0421512956 81 PICCADILLY, LONDON W1V OHL
Tel: 01-629 9556 Cables: Speciprod London W1

1036 Practical Electronics October 1978

 TTL 74* 7494 78 74194 105 4056 134 4513 200 4518 102 4526 199
7495 65 74195 95 4057 2570 4514 265 4519 59 4527 152
7400 13 7496 57 74196 99 4059 480 4515 299 4520 108 4528 99
7401 13 7497 189 74197 85 4060 99 4518 125 4521 268 4529 165
7402 14 74100 119 74198 150 4061 2380 4517 382 4522 199 4530 85
35 CARDIFF RCAD, WATFORD, HERTS., ENGLAND 7403 14 74105 62 75150 110 4062 999
MAIL ORDER, CALLERS WELCOME. Tel. Watford 40588/9 7404 14 74107 29 75491 75 4063 110 LINEAR IC'S
7405 18 74109 64 75492 80 4068 68 702 75, MC1304P 260
7406 38 74110 54 4067 380 709C 14 nin 35 MC1310 175
ALL DEVICES BRAND NEW, FULL SPEC. AND FULLY GUARANTEED. ORDERS 7407 38 74111 68 4068 22 710* 48 MC1312P 195
DESPATCHED BY RETURN OF POST. TERMS OF BUSINESS: CASH/CHEQUE/ 7408 17 74112 88 CMOS* 4069BE 20 723*
733*
45
125
MC1496
MC1488*
92
P.0. OR BANKERS DRAFT WITH ORDER. GOVERNMENT AND EDUCATIONAL 7409 17 74116 198 4000 15 4070 ' 32 99
7410 15 74118 83 4071 21 741C* 8 pin 22 MC1489* 99
INSTITUTIONS' OFFICIAL ORDERS ACCEPTED. TRADE AND EXPORT INQUIRY 7411 20 74119 119 4002 17 4072 21 747C* 70 MC1495* 395
WELCOME. P&P ADD 30p. TO ALL ORDERS UNDER £10.00. OVERSEAS ORDERS 7412 17 74120 115 4006 105 4073 21 7480k 36 MC3401 69
POSTAGE AT COST. AIR/SURFACE. 7413 30 74121 25 4007 18 4075 23 753 150 MC3340P* 150
MINIMUM ORDER £2.00 PLEASE. 7414 51 74122 46 4008 87 4076 85 810 159 MC3360P 89
7416 30 74123 48 4009 50 4077 40 8038CC* 370 MFC400013 85
VAT E portE,orders no VAT, Applicable to U.K. Customers only Unless stated otherwise, ell prices 7417 30 74125 38 4010 50 4078 21 AY -1-0212 580 MFC6040* 97
excluseve of VAT. Neese add 8% to devices marked To the rest add 124% 4011 18 4081 20 AY -1-1313 660 M K50398* 635
7420 18 74126 57
We stock many more items. It pays to visit us. We are situated behind Watford Football 7421 29 74128 74 4012 18 4082 21 AY -1-5051 145 M K50362* 650
Ground. N aaaaa t Underground/BR Station: Watford High Street. Open Monday to Saturday 7422 24 74132 73 4013 42 4085 74 Ay -1-6721/6 195 MM2102-2* 190
9.00 am - 6.00 pm. Ample Free Car Parking space available. 7423 27 74136 73 4014 86 4086 73 AY -3-8500* 385 MM2112* 310
7425 27 74141 56 4015 89 4089 150 AY -3-8710* 750 NE518A* 210
POLYESTER CAPACITORS: Axial lead type (Values are in pF) 7426 36 74142 269 4016 45 4093 85 Ay -5-1224A* 260 NE555* 29
400V: 0.001. 00015. 00022.0.0033 8p; 0.0047. 0.0068. 0.01. 0.015, 0.018 9p; 0022. 7427 27 74143 314 4017 89 4094 190 AY -5-1230* 450 NE556D8* 60
0 033 10p; 0 047. 0 068 14p; 0.10 16p; 0.15. 0.22 22p; 0.33. 0.47 39p; 0.68 45p. 7 35 74144 314 4018 89 4095 105 CA3O11* 82 NE560* 325
160V- 0 039 0 15. 0.22 13p; 0.33. 0.47 22p; as& 1 o 29p; 1.5 33p; 2.2 38p; 4 7 47p. 7430 17 74145 85 4019 48 4096 105 CA3020 170 NE561* 410
DUBILIER: 1000V: 0.01, 0.015 20p; 0.022 22p; 0.047 26p; 0.1 38p; 0.47 43p. 7432 25 74147 175 4020 99 4097 372 CA3023 170 NE562* 410
7433 40 74148 109 4021 91 4098 110 CA3028A* 80 NE565A* 185
POLYESTER RADIAL LEAD (Values in 0/ 250V: FEED THROUGH 7437 30 74150 99 4022 88 4099 145 CA3035 223 NE566* 180
0 01, 0-015; 0-022. 0-027 5p: 0-033.0-047. 0-068.0-1 7P; 0-15 12p; CAPACITORS 7438 33 74151 64 4023 20 4160 109 CA3043 190 NE567* 157
0-22, 0-33 14p: 0.47 16p, 0-68 20p; 1-024p; 1-5 27p; 2-2 31p. 10001350V Sp 7440 17 74153 64 4024 66 4161 109 CA3046 71 NE571* 450
7441 74 74154 96 4025 19 4162 109 CA3048 200 RAM2102-2* 210
ELECTROLYTIC CAPACITORS: Axial lead type (Values are in uFl 500V: 10 409; 47 68p; 7442 68 74155 53 4026 180 4163 109 CA3075 175 RC4136D* 120
250V: 100 65p, 63V 2.2,4.7, 9p; 47. 32, 50 12p;
63, 100 27p; 50V: 1.0 7p 50. 100. 220 25p; 470 50p; 1000, 2200 68p; 40V: 22, 33 9p;
7443
7444
115
112
74156
74157
80
87
4027
4028
45
81
4174
4175
110
99
CA3080E*
CA3081
80 R0M2513* 700
190 SG3402 295
7445 94 74159 210 4029 99 4194 108 CA3089E 210 SN76003N 211
100 129; 3300 62p; 4700 (14g; 35V: 10. 33 7p; 330, 470 32p; 1000 49p; 25V: 10, 22, 47 6P; 390 SN76013N 140
80 100, 160 8p; 220, 250 1 p; 470, 640 25p; 1000 27p; 1500 30p; 2200 41p; 3300 52p; 7446 94 74160 82 4030 50 4408 720 CA3090AQ
4700 54p; 16V: 10 40. 47, 68 7p; 100, 125 8p; 330, 470 16p; 1000, 1500 20p; 2200 34p; 7447 82 74161 92 4031 205 4409 720 CA3123E 200 SN76023N 140
10V:4. 100 6p; 640 10p; 1000 14p. 7448 56 74162 92 4032 100 4410 CA3130*
720 85 SN76033N 211
7450 17 74163 92 4033 145 4411 995 CA3140* 92 SN76115N 215
TAG -END TYPE: 70V: 2000 98p; 4700 121p; 50V: 3000 75p; 40V: 4000 70p; 2500 65p; 196 441201650 ICL7106E* 950 SN76227 115
25V- 4700 48p; 2000 37p; 40V: 2000 + 2000 95p; 326V: 200 + 100+ 50 + 100 19 0p. 7451 17 74164 105 4034
7453 17 74165 108 4035 111 4412E1380 ICM7205* 1150 TAA621AX I 228
OPTO 7454 17 74166 161 4036 325 4415F 795 LD130* 452 TAA661A 155
TANTALUM BEAD C4PACITORS POTENTIOMETERS (AB or EGENI
35V' 010 022 033 047 0.68 Carbon Track. Log & 31N Lyles, values ELECTRONICS* 7460 17 74167 20 4037 100 4415V 795 LM3001H 170 TAA700 353
27p LEDs plus clip 7470 28 74170 230 4038 108 4419 280 LM301A 30 TAA960 300
22N0 33 47 68 25V: I5 10 5000. 1K & 2K Ilin onlyl. Single
74172 625 4039 320 4422 545 110 TBAI20S 70
1

27p TIL209 Red 13 7472 25

20V: 1.5 16V: 1010 13p each 4433 1225 LM308
5K 0-2M0 single gang
60p TIL211 Gm 18 7473 32 74173 170 4040 105 LM318 195 TBA5400 220
47,100 40p. 101/: 229F, 33, 47 6V: 51,0-2M0 Single gang DIP :witch 330
47.68, 100, 3V: 68, 100pF. 20p each SK 0 2M0 dual gang steeeo 70p TIL212 Yellow 22 7474 27 74174 87 4041 80 4435 825 LM324* 79 TBA5500
2" Red 17 7475 38 74175 87 4042 75 4440 1275 LM339* 80 TBA6411011 250
180
MYLAR FILM CAPACITORS
SLIDER POTENTIOMETERS
2" Yellow Green2l ,7476 36 74176 75 4043 94 4450 295 LM348* 120 TBA651
TBA800 90
100V:0001 0002 0005 0010 5p Spare Clips 2 7480 48 74177 78 4044 88 4451 295 LM379*
,1 015 002 0 00 005 0 0560 7p 0 25W log and lenear values 60mm LS400 299 7481 86 74178 102 4045 145 4490F 895 LM380 395 TBA81OS 105
, eF 015 02 9p 50V: 047, 11p SKI) 500K0 single gang 713p T1L307 675 7482 69 74180 85 4046 128 4490V 525 LM381 145 TBA820 70
1060-500K)) dual gang 80p ORP12 68 7483 72 74181 185 4047 87 4501 17 241 595
TDA1022*
CERAMIC CAPACITORS: 50V
LM381AN 320
Sell Stock Graduaied Bezels 209 2N5777 54 7484 95 74182 180 4048 58 4502 120 LM382 TDA2020
125
O SoF to I Orli 3p each 7 Sag Displays 106 74184 135 4049 48 4503 89 TL071CP* 60
7485 LM 1458* 50
'SnF 220 33nF 47nF 4p each
PRESET POTENTIOMETERS TI L312 C An 3" 105 7486 31 74185 135 4050 48 4506 51 LM 3900* TL081CP*
60 52
Bp
Venocal & Horizonlal TIL313 C Cth 3"105 7489 210 74188 275 4051 72 4507 55 LM3909N* TL082CP*
70 96
0 I W 500 5M() Miniature TIL321 C An 5"115 7490 33 74190 115 4052 72 4508 298 LM391 * TL084CP*
125 130
POLYSTYRENE CAPACITORS 8P 198
1000 to InF tip. 1 50 to 47n1 104. 0-25W 1000- 3.3M0 Mow 10p TIL322 C Cth 5"115 7491 75 74191 105 4053 72 4510 99 M252AA* 750 UAAI 70
0 25W 2000- -4-7M0 Von 10p 01704 C Cth .3" 99 7492 38 74192 105 4054 110 4511 150 M253AA* 795 ZN414 105
SILVER MICA Wakes* en pFI 3.3, 0-7 DL707 CA. .3" 99 7493 32 74193 105 4055 128 4512 98 MC1314 88 ZN424 130
68 10 12 18 22 33 47 50 68 75 RESISTORS - Eno make 5% Carbon FND357 140 BF184* 30 0C36* 99 Z1X304 24 2N3442* 131
02 85. 100. 120.150.220 9p each Meneature High Stability Low noese MAN3640
LCD 33 digit
165
975
TRANSISTORS BF194 10 0C41* 48 ZTX311 17 2N3563 20
.' 50 300 330 360 390 600 820169 each
RANGE VAL 1 99 100 AC117* 35 BC170 17 8E195 10 0C42* 32 ZTX314 24 2N36I 4* 169
1000. 1500. 2000 2200 204 each
ieN 220,4 7M E20 1.Sp 1p AC125* 19 8C171 11 BF196 10 0C43* 55 ZTX326 40 2N3615* 135
2p 1.8p SWITCHES* AC126* 19 BC172 10 BF197 10 .0C44* 31 ZTX341 20 2N3663 24
CERAMIC TRIMMER CAPACITORS ON 2.20,4 751 E 12
1W2 -2010M 4p TOGGLE 2A 250V AC127* 18 BC177* 15 8F198 18 20 ZTX500 13 2N3702 10
700 4 15pF 6 250 8 30pF 20p SPST 28p AC128* 18 BC178* 14 8F200* 28 14 2N3703 11
2% Metal Fein, 100.1 M0 Bp 4P 38p 0C46* 28 ZTX501
MINIATURE TYPE TRIMMERS
DPDT AC141* 24 BCI 79* 14 8F224A 18 0070* 19 ZTX502 19 2N3704 10
1% Metal Film 50-1M. too OP 4 pole on/off 54p AC141K* 38 8C182 2N3705 11
5 6pF 3 10pF 10 40pF 22p too gir.re ace phes Ice Resistors each type SUB -MIN TOGGLE
9 8F244 24 0071* 25 ZTX503 16
AC142* 8F256* 0072* 25 2N3706 10
25pF S 45p0 600 88pF 30p not rneeeed e.aeues

PE DIGITAL THERMOMETER
SP changeover
SPST on/off
59p
54p
AC142K* 38910
AC176* 18 BC183L
24
BC183BC182L
10
BF257*
8F258*
50
28
26
0076*
0077*
30 ZTX504
36 ZTX531
76 ZTX550
25 2N3707
25 2N3708
10
10
COMPRESSION TRIMMERS DPDT 6 tags 70p 2N3709 10
i 400 tO 800 25 190pF 25p All parts available. DPDT Centre off 79p AC187* 20 BC184 9 8E259* 30 0079* 76 2N526* 68
1,0 5000 1250pF 38p AC188* 20 BC 184L 10 BF394 22 0081* 28 2N696* 35 2N3710 16
Send SAE for list. DPDT Biased 115*
SLIDE 250V: ACY17 35 BC186 21 BF594 40 0082* 45 2N697* 21 2N3711 10
JACK PLUGS SOCKETS 1A DPDT 14p ACY18* 40 BC187* 28 BF595 38 0083* 48 2N698* 39 2N3715* 250
1A DP clover 15p ACY19* 40 BC2I2 9 0084* 44 2N699* 39 2N3772*170
Screened Plastic open moulded in line }A DPDT 13p ACY20* 40 BC212L 10 BFR40 25 0C122* 48 2N706A* 19 2N3773*288
chrome body metal with couplers 4 pole clover 24p ACY21 35 BC213 9 BFR79 28 0C123* 48 2N707* 50 2N3819 22
2-5mm 12p 8p Bp break PUSH BUTTON ACY22* 40 BC213L 11 BFR80 28 0C139* 85 2N708* 19 2N3820 32
3 5mm 15p 10p contacts 12ipt Spring loaded ACY28* 40 BC214 9 BFX29* 26 0C140* 86 2N914* 32 2N3823* 65
MONO 23p 15 18ip 200 18p SPST on/off ACY39 78 BC214L 10 BFX81* 130 2N3824*
00141* 85 2N916* 27 2N3866* 90 7C
STEREO 31p 18pp 15p 24p 22p SPOT cover 850
85p ACY40* 48 BC307B 14 BFX84* 24 0C170* 40 2N918* 30 2N3903 16
DPDT 6 Tag ACY44 39 BC308 13 BFX85* 24 0C171* 40 2N920* 51 2N3904 18
AD140* 69 BC328 13 BFX86* 28 75 2N930* 18
85pSWITCHES

OC201*
DIN PLUGS SOCKETS InLino * Miniature Non -Locking AD149* 90 BC338 12 BFX87* 23 0C202* 85 2N961* 61 2N3905 18
Push to Make 15p Push to Break 25p 'AD161* 42 BC441* 30 BFX88* 24 0C203* 85 2N1131* 22 2N3906 17
0C204* 85 2N1132* 22 2N4037* 52
. Fe5 Lou0speatte, A0162* 42 BC461* 30 BFY18*
4 5 Pen And. 13p 204 ROCKER (whitel 10A 250V 50
SP ,AF114* 25 5C477* 18 20 43 2N1302* 35 2N4058 17
3
SP changeover centre off 30p EIFY50* TIP29
14p 14p ROCKER: (black) on/off 10A 250V 23p AFF1 *11165* 25 BC547 11 BFY51* 20 TIP29A 44 2N1303* 50 2N4061
2N4064*
17
120
CO -AXIAL ITV) Imp ROCKER: Illuminated lwhitel 25 BC548 11 3FY52* 20 TIP29C 80 2N1304* 50
R10050 Sp 4inglei lap AF117*
Lights when on: 3A 240V 52p 25 BC549 11 BFY71* 20 TIP30 47 2N1305* 28 2N4236* 145
essone0 colours SP Bp double AF118*
ROTARY: ADJUSTABLE STOP) 1 pole/2-12 55 BC557 13 TIP30A 47 2N1306* 35 2N4289 20
Metal Screened 12p 10p 3-rney 41p AF121*
way 2p/2 -6W 3p/2 -4W 4p/2 -3W 48 BC558 12 BSX20* 18 TIP3OB 64 2N1307* 60 2N4859 65
45p AF124*
ROTARY: Mains 250V AC. 4 Amp 55 BCY30* 57 BSY65* 30 TIP30C 65 2N1308* 48 2N5135 42
42
BANANA 4rnm 10p 12p AF125* 36 BCY34* 75 BSY95* 26 TIP31* 40 2N1613* 23 2N5136 20
2mm 10p 104 DIL SOCKETS *(Low Profile - Texas) AF127* 35 BCY39* 40 BSY95A* 25 TIP31A* 40 2N1671*190 2N5138
1mm Be 8 pin 10p; 14 pin 12p; 16 pin 139; 18 pin 20p; AF139* 35 BCY40* 78 BU105 130 TIP31B* 40 2N1671B*195 2N5179*
2N5180*
60
60
WANDER 3nee, 9p 9p 20 pin 27p; 24 pin 30p; 28 pin 42p; 40 pin 55p. AF178* 70 BCY43 76 BU205* 190 TIP31C* 66 2N1893* 28 2N5191* 65
AF180* 70 BCY58* 22 8U208* 225 TIP32* 45 2N1986* 60
AF186* 50 BCY59* 22 E5567 85 TIP32A* 49 2N2160* 105 2N5305* 24
TIP32B* 70 2N2217* 48 2N5457 32
DIGITAL MULTIMETER AF239*
ASY26*
42 BCY70*
40 BCY7 I*
16
15
MD8001*158
ME4102 10 TIP32C* 70 2N2218A*31 2N5458 32
Announcing DM900 - The Digital Multimeter ASY27* 451 BCY72* 16 ME6002 14 TIP33* 80 2N2219A*22 2N5459 32
with a difference - It measures Capacitance too.
las published in E.T.I. August 1978)
VDU CHIP
BC107* 9 BCY78*
BC1078* 10 BD115*
20
62
MJ400*
MJ491* 160
90 TIP33A*r 80 2N2220A*26 2N5485
TIP33B* 100 2N2221* 23
32
2N5777* 54
2N6027 40
BC108* 9 BD121* 95 MJ2955*120 TIP33C* 105 2N2222* 20
Throw away your analogue meters, here's digital
accuracy at only half the price of an equivalent
and MODULE 9C1088* 12 BD123*
8C110098i*
13C 129 B,DD112341**
98
11539
MJE340* 45
MJE370* 55
TIP34* 85
TIP34A* 85
2N2297 45
2N2303* 46
40311*
40313* 125
50

MJE371* 60 TIP34B* 110 2N2368* 21 40316* 85

commercial Multimeter. BC1098* 12 BD132* 38 MJE520* 46 TIP34C* 110 2N2369* 15 40317* 52
40324 85
The DM900 is a 31 digit multimeter with an Convert your TV into a VDU by BC109C* 12 8D133* 43
BC113 17 BD135* 36
MJE521* 65 TIP35* 219
MJE2955*11 TIP35A* 225
2N2476* 125
2N2483* 28 40326* 52
0.5in L.C.D. display incorporating: using the new Thomson-CSF, MJE3055*80 TIP35C* 270 2N2484* 30 40327* 62
TV -CRT controller chip SF.F
BC114 19 BD136* 37 40347* 80
5 AC & DC Voltage ranges; 6 Resistance ranges. BC115 19 80137* 38 MPF102 30 TIP36A* 265 2N2646* 48
96364. 16 lines by 64 characters, BC116 19 8D138* 36 MPF103 36 TIP36C* 325 2N2784* 55 40348* 101
5 AC & DC Current ranges; 4 Capacitance ranges. 40360* 43
BC117 15 BD139* 36 MPF104 36 TIP41A* 63 2N2846* 140
The prototype accuracy is better than 1%. text refreshment, cursor manage- BC118 19 80140* 38 MPF105 38 TIP418* 73 2N2894* 30 40361* 45
40362* 48
This is a unique design using the latest MOS ICs ment on TV screen, line erasing, BC119* 26 80142* 59 MPF106 50
50
TIP42A* 64 2N2904A*22
2N2905A*20 40407* 50
and due to the minimal current drain, is powered line end erasing. Compatible with
BC134 19 BD145* 198 MPF107 TIP428* 82
BC135 20 60222* 80 MPSA05* 24 TIP2955* 63 2N2906* 18 40411* 289
by only one PP3 battery. There is also a battery any computing system. (Send 20p BC136 18 BD695A* 75 MPSA06* 24 TIP3055* 52 2N2907* 20 40412* 63
check facility. plus SAE for full technical data.) 5C137 20 BD696A* 75 MPSA12 40 TIS43 36 2N2907A*22 40467 95
BC140* 28 BDY17* 195 MPSA55 24 TIS44 45 2N2926G 10 40576* 190
DM900 is an attractive hand-held lightweight SFF 96364E 611.50. BC142* MPSA55 24 45 2N29260 40594* 80
25 BDY60* 110 TIS46
device, built into a high impact case with carrying AY -5-1013 UART 64.50* BC143* 25 BDY61* 165 MPSA70 34 TIS50 47 2N2926R 8 40595* 90
handle and has been ingeniously designed to 71301 ROM 68.20* BCI47 7 5F115* 22 MPSUO2* 58 TIS60 45 2N2926Y 8 40603* 85
simplify assembly. 62.05° BC148 7 BF154* 25 MPSUO5 48 TIS62 45 2N3011* 24 40636* 125
SFS80102 RAM 1K 582114,39 8 BFI 56* 29 MPSUO5 54 TIS74 47 2N3053* 20 40673* 88
Never before have all these features been offered 74LS163 RAM 60.95. 14 8F167 25 MPSU52* 65 TIS90 18 2N3054* 49
to the electronics enthusiast in a single unit. Complete module 6136.50. BC154 14 BF173* 25 MPSU55* 63 T1591 22 2N3055* 55
BC157 10 BF177* 24 MPSU56* 56 ZTX107 11 2N3108 39
40
Diodes
Price: 854.50. only (p&p insured add 75p) BC158 11 BF178* 25 MPU131* 39 ZTX108 11' 2N3121 4
ASCII Keyboards' BC159 11 13F179* 30 0C25* 120 ZTX109 11 :2N3133 43 11,14148
CR033* 148
Ready Built units available on order Full 56 Key ASC II coded key- BC160 27 BF180* 20 0C26* 150 ZTX300 13 I 2N3135 33 Zeners 400mw
boards now available. BC167A 11 BF181* 30 0C28* 99 ZTX301 16 2N3250 30 2 7-33v 9
Send SAE for leaflet. BC168C 12 BF182* 30 0C29* 180 ZTX302 18' 2N3252 36
(Demonstration on at our shop) 649.50* (P & P 75p1 BC169C 10 BF183* 30 0C35* 80 ZTX303 21 2N3302 35'

I'rartical Electronics October 1978 1037

 1 y

THE PIONEERS OF MODULAR DISCO/P.A. EQUIPMENT

NOW OFFER PACKAGE DEALS AT INCOMPARABLE PRICES

CENTAUR COMPLETE STEREO

ROADSHOWS - BUILT IN MINI DISCO
STEREO DISCOS SOUND TO LIGHT/SEQUENCER
& DISPLAY 100 WATT
C/W LIGHT SHOW & DISPLAY,
TWIN SPEAKERS & LEADS ,.,,TWO YEAR GUARANTEE MONO SYSTEM
,,,,,,,.... .......... £179.50 Deposit £41.66
Standard 100W ..,
12 Months 4 £15.56

£249 or Deposit £57.12 + Carr. £15

12 Months g £21.75 or 24 Months @ £12.26

+ cam £15 I, Similar in appearance to the Centaur and
complete with loudspeakers and leads.

Super 200W A 6S,

Headphones to suit any system
EM507 Electret Mic
ECM 81 Electret Mic
£7.50
£15.00
£19.95

£299 or Deposit £68.12

" '''' ''' .11L
to Boom Stand
Carriage on all disco and PA systems
£15.50
£10.00
12 Months u £25.86 or 24 Months 4 £14.56 (Included in H.P. Prices)
+ corr. £15

GXL 200W( wwaithtitcwaibnin2e0Ots illustration shows GX1 Centaur System

systems feature full mixing for two decks
tape 8 mic with monitoring facilities - override
20% Deposit Terms
£389 _ or Deposit £87.32
and are supplied complete w:+ sound to light
sequencer, display, speaker leads etc.
, On All Orders
12 Months @ £33.31 or 24 Months @ £18.76
JUST PLUG IN AND GO!
Over £150 - 12 or 24
+ corr. £15
BSR Decks - 17,000 Line Loudspeakers - Rugged Aluminium Trimmed Cabinets - Cue Light And Phones Months - Low Interest
Output - Slave Output - Deck Lights/Motor Starts (GXL)

D.I.Y. MODULES FOR ALL DISCO/P.A. AMPLIFIERS DISCO MIXERS - COMPLETE OR MODULAR
£9.95* 'Z1'0%1. £10.90* --s--i`"-
SA308 30W 8 ohms 45V
SA604 60W 4 ohms 50V £13.25
«,:(0,,,,,,,fpoui,,, )
k i
r
4....
1 "5 '3 ') 1 C) 0 C) (3 (3 ID (3
MONO OR STEREO
WITH AUTOFADE

SA608 60W 8 ohms 65V £14.25 ZioZus £13'50 MODULES

Available complete and ready to plug in or as an Mono module E22.50
SA1204 120W 4 ohms 15V £15.95 ' 7=, 0 , easy to connect module with all controls except Stereo module E33.50
monitor switch already fitted - full instructions Panel E3.95
SAI208 120W 8 ohms 95V £21.00 siZZLis £22.50 ts supplied. Kit of knobs/sockets etc E5.50
SA2404 240W 4 ohms 95V £29.50 '0= FEATURES INCLUDE:
COMPLETE MIXERS (with case)
Mono I 8V E39.50
0 2% Distortion, 30Hz20, KHz , 2dB, Fully Short/Open Circuit proof input
Twin Deck - Mt< 8 Tape Inputs - Wide range bass
sensity
itiv 240 mV to suit most mixers - D.C. 8 Output Fuses fitted Stereo 18V E57.50
'fif ' 8 treble controls - Full headphone monitoring - Mono mein, E45.75
c,o,rod.- Professional standard performonce. Stereo mains (63.75
TOP QUALITY COMPONENTS THROUGHOUT

COMPLETE LIGHTING CONTROL AT YOUR FINGERTIPS! STROBE UNITS

Lighting Control Unit Mk II E44.50
.41 ...11 -41111 Id 4kW Sequencer Sound Light Dimmers
Automatic Level Integrated Logic Pro -Strobe 4-6 Joules £37.50
co, in, tn, In, Circuitry
Module E32.50
Panel £2.95 Super Strobe 2-3 Joules £22.50
.").1. Three Channel Sound to Light
3kW 1-240W input - master
£26.75
Module E19.75
» (Pro -Strobe has external trigger
facility).
Plus channel controls Panel E2.95

SPARES & ACCESSORIES - LOUDSPEAKERS & CABINETS PROJECTORS - PLUTO - NEW LOW PRICES!!!
Rope Lights - Red or Multicolour £39.50 Melos Echo Chamber £59.00 CHOICE OF WHEEL/CASSETTE
per 30ft. Headphones £7.50*
Rope Light Controller for up to 120 ft £30.00 Sirens: English Police, USA Police, P150 150W Tungsten £37.50 Liquid wheels £7.50
Fuzz Lights-Red/Blue/Yellow/Green E22.80 P500 100W O.I. £74.95 Cassettes £8.00
Destroyer, Alien Voice Simulator £7.50 P500 250W 0.1. £84.95 Picture wheels from £4.75
Magnetic Cartridge Equalisers (3.50* Bulgin 8 way lighting plug/socket E1.90 (Wide choice available)

100 Watt Chassis Loudspeakers 12" £23.50 18" £47.50 (Add (I 50 corr
PIEZO HORNS only £7.50
:

Empty Loudspeaker Cabinets: Small 12" Large 12" £21.50 Small 2 x 12" E22.50
E15.50, Large 2 x 12" E28 1 x 18" E29.50 YES! - only £7.50
Projector lamps: Al 167 E2.90. M6 E5.65. Strobe tubes 80W E8.50 As fitted to our package PA system)
100W Spot lamps Red/Blue/Yellow/Green ICI Vynide 50" wide E3.50 Metre Direct from Motorola Inc., USA at an
E1 .50 ea E13.50 for 10 Kickproof Grille 24" wide £3.25 Metre UNBEATABLE PRICE
MD Spot Banks: 3 -way 300W £19.50, Kick Resistant Grill 50" wide (3.25 Metre. No crossover required 4kHz - 30kHz rated
4 -way 400W (22.50. FULL RANGE OF REAN PRODUCTS IN STOCK 75W/8 ohms 150W/4 ohms use two per 100W
Bubble machines (optikinetics) £41.50 SEND FOR OUR BROCHURE NOW!! amplifier - Full instructions supplied.

1038
Practical Electronics October 1978
 BAD NEWS FOR KNOB TRIAC BARGAINS
TWIDDLERS 400V Plastic Case

PACKAGE P.A. A 300W Lightdimmer with NO knob. Dariming and on/ott

functions are controlled by touch. Feature=. include:
3A
6.5A with trigger
8A
84p
869
80p
12A 90p
* No mains rewiring.
16A 113p
* Easy to build - uses one MOS 1C.
SYSTEMS (Guarantee) * Switches on to preset brightness.
* Can be switched and dimmed
20A
25A
178p
2059
SCR IC106131 5A/400V 54p
from many locations using TDE(K
Complete with PIEZO horn columns fitted with 100 watt kit making 2 -way switching easy.
Diac 23p

units (100 watt system illustrated) ** PRICE £9.67 TDE/K £1.08.

COMPONENTS
100 Watt f159.90 LIGHTING CONTROL KITS 13001M TSD300K TOUCH -
SWITCH & DIMMER combined. One touchplate for on/off.
£5.62
0.2" L.E.s
Red 11p (813p,101
Deposit £38.46 Small knob controls brightness.
TS300K TOUCHSWITCH. Two touchplates, ON/OFF £4.32.
Green 23p Yellow
DL72 7 .5" display
27p
£1.62
12 Months w £14.28 TSA300K AUTOMATIC. One touchplate. Preset time LCD .5" 4 digit £9.72
delay off. £4.32 LEM .5" dia. 45p
Includes 4 Channel 100 Watt Amplifier with - £3.02 NE555 31p 14 for El .081
LD300K LIGHIDIMMER
Treble, Bass and Master Controls plus Leads 741 27p 15 for £1 .081
LM3911 temperature
and Twin Piezo Horn Columns (shown on right). DIGITAL VOLTMETER/THERMOMETER KIT IC £1.08
AY -5-1224 £3.51
£5.23
200 Watt £249.00 '1-gr. ". ........ AY -5-1230
ZN1034E £1.94
Based on the 7106 single ICL7106 DVM IC £9.99
Deposit £57.12 IC 33 digit D.V.M. the IN4001
IN4148
7p
5p
Kit contains a PCB, re- I 1p
12 Months@ £19.11 or 24 Months @ £10.66 sistors, capacitors, pre-
BC182L
2N3819 25p
zsix Mixed Inputs plus Three Sets of Bass and sets. I.C. and 0.5" liquid
Treble Controls plus Slave Output and Master crystal display. Com-
ponents are also included MINI MAINS
Control. to enable the basic D.V.M.
kit to be modified to TRANSFORMERS
a Digital Thermometer
ACCESSORIES using a single transistor
Standard 240V mains primary
100mA secondary
Melos Echo Unit £59.00 as the sensor.
ONLY £23.75
6-0-6V 92p
A high quality Cassette Tape Echo Unit giving 9-0-9V 97p
12-0 12V 102p
long tape life, infinitely variable echo depth
and speed control. Suitable for all mics. and 24HR CLOCK/APPLIANCE TIMER KIT
instruments.
Switches any appliance of up to 1KWon and oft at
High quality Boom Stand £15.50. Floor preset times once a day. KIT contains: AY -5-12 30
Stand £9.90. ECM81 Condenser Mic. - Clock/Appliance Timer IC, 0.5" LED display,
Removable Lead - Good Anti -Feedback mains supply, display drivers, switches, LEDs. triec.
£19.95.* EM507 Condenser Mic. - Good complete with PCBs and full instructions. £14.85
White box 156 x 131 x 71mm) - drilled £2.70
Value £15.00. Phasers £19.80. - undrilled £2.38

ABOVE PRICES INCLUDE V.A.T.

D.I.Y. MODULES FOR P.A. SYSTEMS Mono or stereo Quantity discounts on request. Add 25p postage and packing. Mail order only to:
Make your own mixer - Mono/Stereo - up to 20 channels
T.K. ELECTRONICS (PE) 106 Studley Grange Road, London, W7 2LX
with these, easy to wire modules - Available as PCB's or
assembled on panels.
Input Stages MonoMono
E CiW
Up to 10 panel etc £8.95
Motorola, 1 WATT AUDIO AMPLIFIER I.C.
9-16V 8-160, 10-400MV sensitivity, S.C. proof, no heat sink required. Supplied with doto and cecurts,
Stereo
S

£9.50 £12.50 90p. Doto ond circuits olone, 20p + SAE.

C,ptceBreo

panel etc.W BARGAIN PACKS

Don't let your environment dehydrote you. VERNITRON FM4 10-7mHz minioture cer-
Buy a Honeywell Humidity Controller mem. ouuc fillers 50p each. 3 for £1.00.
Mixer/Monitor Mono (/W
One only
MonoP(l

£5.95 panel etc. £8.95 bran° operated with 1" shaft, ideal for green.
houses, centrally heated homes, etc. Build your
Miniature mains transformers, fully shroud.
ed. 240V in 6-0-6V at 100MA. out. Ex. New
own humidity alarm, 3.75A. Contacts at 250V equipment, complete with mains lead ond plug
per system)
£1.50 each. 3 for £4.00 on input ond short leads on output. 95p.
Stereo z.n, cal Stereo (/W 4 aluminium boxes 128 x 44 x 38 mm ideal for Semiconductor Bargains
L 7 .JAJ panel etc. £12 .50 signal injectors, etc. £1.00. 1113 Thermistors 10 for £1.00.
100 miniature read switches ideal for 100 new and marked transistors. Lots of types
burglar alarms, model railways, etc. £3.30. including BCI 48, BC154, 0F274, BC212L, BF200
Power supply for Blank 6 x 6 -pole 12 volt reed relays on board etc. £4.95.
up to 20 channels £9.50 panel £1.00 £2.45. 200 new and marked transistors, including all
above plus 2N3055, AC128, 8E1'50, BD131etc.
High quality computer panels smothered in top
Send for free brochure for complete specification grade components: S lbs £4.75; 10 lbs £8.95. £9.95.
100 mixed diodes including zener, power and
Miniature edgewise pone) mounting level
meters 200 ua.fsd 90p.
bridge types Marked and Unmarked £2.95.
Miniature transistorised f.m. front end with Bridge rectifier 100V 2.5 amp. 4 for £1.00.
Saxon AP100 Amplifier £45 integral tuning gong 88-108MHz £2.50. Brand new ITT 25kV T.V. triplers for Dec.
New U.H.F. transistor TV tuners Bradford chassis £2.50. 5 for £10.00.
Four mixing inputs - 100W into 4 ohms 50 Germanium diodes ideal for crystal sets
Wide range bass 8 treble controls Rotary type with slow drive and AE. socket etc. £1.00.
master - Twin outputs £2.50. Full spec. I.R. diodes, 200V 1A. 20 for £1.00.
Aluminium TV coon plugs. 10 for £1.00. 100 for £4.50. SN76115N £1.00.
Saxon 150 Amplifier £59 Hardware Packs each containing 100's of items BF200, 6 for £1. BC212L, 10 for £1.
Four mixing inputs - 100W into 8 ohms including: BA nuts and bolts, Nylon, Self - BC154, 12 for £1. BF274, 12 for £1.
rapping, Posidrive, clips, Coble clamps, BC148, 12 for £1.
150W into 4 ohms - wide range bass Fuse holders, Spire nuts etc, etc. £1.00 per Varicap diodes, 10 for £1.
8 treble controls master pound. 'Heavily inssilated E.H.T. Dischorging Component Bargains
Probe with lead and earth connector 60p each. 300 mixed resistors watt £1.50. 300
Ultrasonic transducers, tronsminer and re- modern mixed cops, most types, £3.30. 200
All prices subject to 8% VAT except where asterisked (12;%) ceiver 14mm diom. 40kcs £4.25 per pair.
Magnetic earpieces with plug and lead 25p
mixed resistors, mostly 1 & 2 watt, £1.50. 100
1.30 pm mixed polyester cops £2.20.100 mixed modern
Shop premises open Tues to Sot 9 am - 5 pm Lunch 12.30 -
each. 5 for £1.00. miniature and ceramic plate caps £1.20. 100
Mail order dept open Mon to Fri 10 am - 4 pm Ring 01-684 6385 Crystal earpieces with lead 40p each. 3 for mixed electrolytics £2.20. 300 printed circuit
£1.00. resistors £1.00. 25 mixed pots and presets
10 assorted convergence pots £1 £1.50. 100 mixed carbon film and metal film
TO ORDER 12 quit, low profile I.C. sockets, 14 pin £1 resistors mostly miniature lots of values, £1.20.
Send your requirements with cheque crossed P.O or 500 for £4.90. 100 mixed high wattage
By Post DE LUXE FIBRE GLASS
resistors, wirewound, etc. £2.20. 20 assorted
60p COD charge to address below or lust send your PRINTED CIRCUIT ETCHING KITS
VDRs and Thermistors £1.20. 25 assorted
Includes 150 sq. ins. copper clod f/g board,
Access or Barclay Card Number NOT THE CARD I lb ferric chloride, I dohs etch resist pen, preset pots, skeleton, etc. £1.20.
abrasive cleaner, 2 mini drill bits, etch tray and Bargain Parcels Save Pounds
By Phone You may order COD, Access or Barclay Card. Huge quantities of electronic components must
instructions- only £5.30.
Post & Packing 50p on all orders except where stated. 150 sq. in. fibre gloss board £2.00 be cleared as space required. 1000's of
Delo pen 90p capacitors, resistors, transistors. Ex equipment
1 lb ferric chloride to mil spec £1.25 panels etc. covered in valuable components.
No time to sort. Must sell by weight 7 lbs -
SAXON ENTERTAINMENTS 5 lbs ferric chloride to mil spec
Instruction sheet
£5.00
20p £4.95, 14 lbs - £7.95.
327 Whitehorse Road, Croydon, Surrey. 40p P & P ON ALL ABOVE ITEMS. SEND CHEQUE OR POSTAL ORDER WITH
All Enquiries Lcrqe SAE Please Brochures on request ORDER TO SENTINEL SUPPLY, DEPT PE, 149A BROOKMILL RD., DEPTFORD 5E8

October 1978 1039

Practical Electronics
 The latest kit STORAGE CABINETS

innovation! Metal cabinets with

transparent plastic
drawers. Ideal for
components, small

SUNIAlita parts, nuts, bolts

etc. Many other
uses in the home,
workshop, laboratory
etc.
Type 1118

Choose from the following range to suit your own

needs:

Type Height No. of Drawers Price

(ins.) Total Small Medium Large
1,118 11 18 15 2 £8.65
1130 11 30 30 £8.95
1633 16 33 30 2 £10.95
the quickest fitting
1

1150 18 50 50 £12.95
1860 22 60 60 £14.95
CLIP ON All cabinets are finished Blue, 12" wide x 51" deep.
Prices include VAT and Post. Satisfaction or money
capacitive discharge refunded. Cheque/P.O. to:
electronic ignition
in KIT FORM MI LLHI LL SUPPLIES (TOOLS)
Smoother running 35 PRESTON CROWMARSH,
Instant all-weather starting BENSON, OXON. OX9 6SL
Continual peak performance
Longer coil/battery/plug life
Improved acceleration/top speeds
Optimum fuel consumption Random
Sparkrite X4 is a high performance, high quality capacitive discharge, electronic

ro
ignition system in kit form. Tried, tested, proven, reliable and complete. It can be
assembled in two or three hours and fitted in 1/3 reins. FLASHERIINiT TWIN BANK 6LIGHT
I less lamps)
Because of the superb design of the Sparkrite circuit it completely eliminates LENGTH
problems of the contact breaker. There is no misfire due to contact breaker 14t inches UNIT
bounce which is eliminated electronically by a pulse suppression circuit which
prevents the unit firing if the points bounce open at high R.P.M. Contact breaker
burn is eliminated by reducing the current to about 1 /50th of the norm. It will
perform equally well with new, old, or even badly pitted points and is not
) (4qP Sri Faring
vw.re
dependent upon the dwell time of the contact breakers for recharging the system.
Sparkrite incorporates a short circuit protected inverter which eliminates the
problems of SCR lock on and, therefore, eliminates the possibility of blowing the
Complete velth three
100watt coloured lam
[19 .95 2E181.35
that flash independe
rando
transistors or the SCR. (Most capacitive discharge ignitions are not completely ES
foolproof in this respect). The circuit incorporates a voltage regulated output for Fitting L11.35
greatly improved cold starting. The circuit includes built in static timing light,
systems function light, and security changeover switch. All kits fit vehicles with
coil 'distributor ignition up to 8 cylinders. Sound to Light 600
THE KIT COMPRISES EVERYTHING NEEDED
Die pressed epoxy coated case. Ready drilled, aluminium extruded base and heat
MASTER UNIT WATTS
PER
TYPE A s POT
sink, coil mounting clips, and accessories. Top quality 5 year guaranteed 111111mwougommior CHANNEL fiessIampf
transformer and components, cables, connectors, P.C.B., nuts, bolts and silicon fi)
grease. Full instructions to assemble kit neg. or pos. earth and fully illustrated
F.,14q4
installation instructions.
NOTE -- Vehicles with current impulse tachometers (Smiths code on dial RV1)
will require a tachometer pulse slave unit. Price E3.35 inc. VAT. post Et packing.
1
".'s ^*. 5ourr
IMO
Electronics Design Associates, Dept. PEI°, 82 Bath Street, Walsall,
WS1 3DE. Phone: (9) 614791 B C Fitting
TYPE B 3 BANK UNIT E S Fitt.q
(Less 1-C.,,Ps) fj3Q(rIf.30 4Y

Electronics Design Associates, Dept. PE10

82 Bath Street, Walsall, WS1 3DE. Phone: (9) 614791
Name
TWIN BANK
Address BC
Fitting
£7.99 E S
F 'fling
0.99 UNITen,h

Phone your order with Access or Barclaycard 31

Inc V.A.T. one P.P. QUANTITY REO'D.
Send SAE if brochure only revered.
100 WATT SPOT LAMPS
RED YELLOW GREEN Slimes
%L.... "NXIci Pe'Ro 4

I enclose chequelPO's far

BLUE C1 50 each f4 50 (less Limp,
54 KIT £14.95 CLEAR
or E S Mins
FA,, £1,50
C

TACHS PULSE SLAVE UNIT £3.35

£ t uiCt uof v and POSY a 1,(1111IL
Fir ,gf 111501
Cheque No. a et
Sand 20. for Mammal
Please state polarity pos or neg earth.
Access(); Barclaycard No. A L BEN ENGINEERING CO. LTD.,
DEPT PE THE CRESCENT WORSTHORNE,
BURNLEY LANCS. Tel Burnley 20940
1040
Practical Llectronics October 1978
ELECTRMTIE Bugin9 Guide
If you have bought from Electrovalue, you will know just how large and varied our stocks are. For those who have yet to know, we
are publishing a series of five ads. month by month to give up-to-date information and prices on the most important items we carry.
These ads. will appear in stepped rotation in five journals - Pr. Electronics. Pr. Wireless, Everyday Electronics, Electronics Today
Intntnl. and Elektor so that the complete series will be available each month. In this way, no matter which journals you read.
BY DETACHING AND SAVING THESE PAGES, YOU WILL HAVE A VALUABLE AND COMPREHENSIVE MONEY SAVING
Section 2 Nik
CATALOGUE. ALL MERCHANDISE IS BRAND NEW AND GUARANTEED.

Capacitors pF volts
21p
Quantity prices available except for M DC.

ELECTROLYTIC. R1524, 28.0 x 17.8mm 0.1 400 15p POLYESTER,

CERAMIC DISC 10 6.3
0.1 630 25p 832563 PCM
3p 10 25 12p TANTALUM BEAD 330 18p
500V: 1,2. 5nF 0.12 250 13p 1.0 400 72p
3p 40 12p Siemens 845134 series 390, 470. 500 18p
50V: 0.021F 10
volts I 8p 0.15 250 14p (Good pulse discharge ratings)
14p pF 560, 680
50V: 0.050 4p 10 63
35 14p 820, 1000 22p 0.22 250 15p
10 100 15p 0.1 POLYPROPYLENE.
CERAMIC FLAT 0.15 35 12p 2200 24p 0.33 250 18p
22 10 12p 833063, 160V
TUBULAR B374480 12p 0.22 35 14p 3300 36p 0.47 250 21p
22 25 27p 100. 470, 680pF 49
12.5mml 13p 0.47 35 14p 4700 46p 0.68 250
0.01pF 63V 4p 22 40 31p 2200, 4700, 5600pF 69
15p 0.68 35 14p R2032, 35.6 x 23.0mm 1.0 250 4p
0.022pF 40V # 3p 22 63 46p 5100pf
16p 1.0 35 14p 1500, 1800 18p 1.0 400 8p
5p 22 100 51p 6800. 10.000pF
0.022pF 63V 12p 2.2 16 14p 2200. 2700 24p 2.2 250
0.033pF 63V 5p 47 3
1.04 POLYSTYRENE.
12p 2.2 35 14p 3600. 3900 29p 4.7 250
0.0475F 63V 5p 47 10 1.81 B31110, 160V
14p 3.3 16 14p 4700, 5000 33p 10 250
0.0685F 63V 6p 47 25 5, 7, 10, 12pF Bp
47 40 15p 4.7 16 16p 6800 41p
CERAMIC FLAT 4.7 35 18p 56p POLYESTER, 15, 22, 27, 33pF Bp
47 63 16p 8200. 10.000
TUBULAR 8374490 832560 PCM 7.5mm 39pF 6p
47 100 19p 6.8 25 18p
15mm) 6.3 16p MIXED DIELECTRIC, pF volts 47. 56. 68, 82pF 5p
100 3 12p 10
0.0475F 63V 5p M.D.C. 0.001 250 6p 100, 120, 150pF 5p
100 10 14p 10 16 18p
0.068pF 63V 5p 25 20p 600V 0.0015 250 8p 160, 180. 220pF 5p
100 16 15p 10
0.15F 63V Bp 31p 0.1 27p; 0.47 72p; 0.0022 250 6p 270. 330. 390pF 5p
100 25 16p 15 25
11p 1000V 0.0033 250 6p 470. 560pF 5p
0.225F 63V 100 40 16p 22 6.3 18p
22 16 22p 0.001, 0.0022, 0.0047 113P 0.0047 250 6p POLYSTYRENE,
CERAMIC PLATE 100 63 22p 0.01 20p; 0.022 21p; Bp
1Mullard C333l 100 100 28p 22 25 45p 0.0068 250 831310, 160V
0.1 27p; 0.22 48p; 0.0082 250 7p 560. 680. 820pF 5p
E12 values 220 3 13p 33 10 22p
47 6.3 22p POLYESTER, 0.01 250 6p 1007. 1500 5p
1.8pF - 18pF 4p 220 6.3 15p
47 16 35p Mullard C2130, PC tg. 0.012 250 7p 2200, 3300pF 5p
220 10 15p
CERAMIC PLATE 17p 100 3 22p 0.01. 0.015 Bp 0.015 250 6p 1200, 1800, 2700 Bp
E12 values 220 16
250 8p
20p 100 6.3 45p 0.022 6p 0.018 3900, 4700 8p
22 - 33pF 3p 220 25
250 7p
24p 100 10 67p 0.033, 0.047 6p 0.022 5600, 6800. 8200 Bp
39 - 68pF 3p 220 40
30p 0.068 7p 0.027 250 Bp 10000p F
82 - 220pF 3p 220 63 ELECTROLYTIC. 7p
47p 0.1 7p 0.033 250 12000, 15000 12p
270- 1000pF 3p 220 100 TANTALUM. AXIAL 250 Bp
6.3 16p 0.15 8p 0.039 18000. 22000 13p
E6 values 470 Siemens series D. 7p
19p 0.22 9p 0.047 250
1500 - 4700pF 3p 470 10 0.1/35. 0.47/35, 1/35 36p 250 9p TRIMMER CAPACITORS
24p 0.33 13p 0.056
6800pF 3p 470 16 2.2/20, 4.7/10 35p 0.068 250 8p Polypropylene. 100V, 0.1"
470 25 22p 0.47 15p
2.2/35, 4.7/35 37p 24p 0.082 250 11p matrix
CERAMIC FEED 470 40 31p 37p 0.68, 1.0 2-10pF 23p
10/20, 22/15 42p 0.1 250 9p
THROUGH 470 63 49p 47/10 66p 1.5, 2.2
5.5-65pF 34p
1000pF 350V 5p 0.1 100 9p
470 100 74p 2-22pF 27p
POLYESTER. 0.12 100 12p
ELECTROLYTIC, 1000 3 18p LACQUER FILM PC mounting 0.15 100 10p VARIABLE CAPACITORS
REVERSIBLE 1000 6.3 22p Jackson 'Dilicon' solid dielec.
(non -polarised) Mallard 344- or Siemens 0.18 100 14p
EX50 series, 50V. 1000 10 21p 200pF 1.82
Siemens 832110 832234- series as available 0.22 100 12p 100pF 1.70
26F 25p 1000 16 30p series 20% tol. 300pF 1.96 500pF 2.20
100V 0.27 100 19p
4. 68F 27p 1000 25 40p volts
pF 0.047 9p 0.33 100 16p Jackson C804,
8, 10, 165F 30p 1000 40 45p 78p
0.1 100 0.068 9p 0.39 100 23p air dielectric.
250 35p 1000 63 76p 0.15 63 62p 60pF 1.88
23p 0.1 10p 0.47 100 20p 5pF 1.39
40, 605F 56p 2200 3
0.22 63 65p 11p 30p 20pF 1.48 150pF 1.89
2200 30p 0.15 0.56 100
100pF 65p 10
0.33 63 70p 12p 100 25p 50pF 1.48 15pF 1.39
2200 16 45p 0.22 0.68
ELECTROLYTIC, CANS 0.47 63 78p 0,33 I6p 100pF 1.71 30pF 1.86
2200 25 70p 63 849 75pF 1.66
Siemens 841070. 0.68 0.47 18p POLYESTER. 10pF 1.39
2200 40 77p 63 91p
unsleeved 1.0 0.68 22p B32561 PCM 25pF 1.39
4700 16 85p 100 1.45 Jackson Ball Drives, 61
1000pF 40V .99p 96p
1.0 1.0 27p 0.01 250 5p
1.07
4700 25 1.0 250 2.01 451180 1.38
1000pF 63V 10,000 3 40p 2.2 46p 0.022 250 6p
1000pF 100V 1.60 1.5 63 93p 4.7 79p 7p 4511DA 1.38
1.80 0.047 250
22005F 25V 1.08 ELECTROLYTIC, 2.2 63 6.8 1.08 0.1 250 9p 4489 with calibrated dial4.88
22005F 40V 1.21 PLUGGABLE 3.3 63 1.82
63 2.07
250V 0.22 100 11p CAPACITOR CLIPS
22000F 63V 1.50 Siemens 841316 series 4.7 0.01 6p 0.47 100 17p HORIZONTAL
4700pF 25V 1.46 pF volts 6.8 63 2.59 0.015 6p 28p
1.0 100 25mm Bp 35mm Bp
4700pF 40V 1.50 1.0 63 13p 10 63 3.00 0.022 Bp
5.08
44mm 11p
4700pF 63V 2.04 2.2 63 13p 10 100 0.033 Bp VERTICAL
POLYESTER,
ELECTROLYTIC. CANS 4.7 63 13p 0.047 8p 832562 PCM 25mm Bp 30mm 14p
Daly, sleeved 10 63 13p SILVERED MICA, 350V 0.1 11p 17p 8p 41mm 8p
0.47 100 35mm
1000/25 48p 22 40 13p 1% (or 3pFl 0.68 24p 1.0 100 30p 44mm 10p 51mm 14p
2200/50 94p 22 63 14p R611. 12.7 x 8mm. All in pF. 0.82 24p 100 48p 64mm #14p
2.2
5000/25 98p 47 16 13p 2.2. 3.3, 5 11p 1.0 27p
4700/100 3.61 47 40 14p 6.8, 10, 15 11p 2.2 48p
47 63 18.20.22,25 11p 400V
ELECTROLYTIC, 6.3 14p 11p 7p
100 27, 30, 33 0.01
axial lead 100 14p 11p 7p
16 39. 47, 50 0.015
Siemens 841313/ 15p 11p
841283/841010 100 25 56, 68
POLYESTER, Axial lead
ANOTHER ELECTROVALUE SPECIAL
100 40 18p 100 12p
pF volts Siemens 832231 series We are now National Distributors for
21p 100 63 24p 150 14p
0.47 63 volts
220 3 8p 220 17p pF
0.47
1,0
100
40
12p
21p 220
220
10
16
16p
18p
330
R1015, 16.5 x 11.4mm
20p 001 630
0.015 630
13p
13p
NASCOM I
1.0
2.2
100
25
12p
12p 220 25 19p 82,100 11p 0.022 630 13p MICROCOMPUTER KITS
220 40 23p 120, 150 11p 0.033 400 13p
2.2
2.2
63
100
12p
12p 470 6.3 16p 180, 200, 220 12p 0.047 250 13p for delivery from £197.50
21p 470 10 19p 250.270. 300 12p 0047 400 14p stock. Net from + V.A.T.
4.7 16
0.047 630 16p
12p 470 25 25p 330 15p Quantity discounts. Trade Enquiries invited.
4.7 40 16p 0.068 250 14p
12p 470 40 29p 470
4.7 63 250 14p
14p 1000 16 26p 1000 20p 0.1
4.7 100

GOODS SENT POST FREE U.K. on C.W.0 orders For ACCESS or BARCLAYCARD orders, just phone
over £5 list value. If under, add 27p. handling or write your number.
charge.

ATTRACTIVE DISCOUNTS on C.W.O. orders -

No discounts allowable on prices marked NET or N
TEAR OUT AND TAKE GOOD CARE OF THIS
PAGE AND REMEMBER TO LOOK OUT FOR
ELECTROW-ME LTD
5% where list value is over £10; 10% where list NEXT MONTH'S TO ADD TO IT. 28, ST. JUDES ROAD, ENGLEFIELD GREEN.
value is of £25.
OUR COMPUTER -AIDED SERVICE TAKES EGHAM, SURREY TW20 OHB
TOP QUALITY MERCHANDISE - ALL GOOD CARE OF YOUR ORDER NO MATTER Telephone Egham 3603 Telex 264475
GUARANTEED. HOW LARGE OR SMALL.
V.A.T. - add 8% to value of order. For items COMPREHENSIVE PRICE LIST FREE ON Northern Branch -680.BURNAGE LANE.
marked add 12 REQUEST.
BURNAGE, MANCHESTER M19 1NA(061)432 4945
 WICLA.C.MID
ELECTRONIC COMPONENT CENTRE
58-60 GROVE ROAD, WINDSOR, BERKS
SL4 1HS (TRADE AND EXPORT WELCOME)
HOTLINE FOR TELEPHONE CREDIT CARD ORDERS -
ELECTRONICS LTD. WINDSOR 54525
PMPRICE)
SEMICONDUCTOR DISTRIBUTORS
E RDSI OCFOFUE NR OF VOERR f01000DISCOUNTONE ES;000. oF Fo. Ff H1
QUANTITY
Chinn. or cash orders over ES Post Free. Other orders add 20p Post & Pecking Credit Cord corcr ES mere by post or phone.. Post 8. Pecking 20p UN odd 8 r. to precos
merited'. Add 12 V, % VAT to ell other prices. Free price list send S A E
AN devices to makes. specifications. Plea. quote FT! ed es prices mile change. E 8.0 E 1078 C Alen wolconne Tame to Sot (Lunch 1-2).
6"x4" Oil Board (2.25* DISCO TRIAC 10A 400v TRANSISTORS 7400N SERIES TTL CMOS TOP VALUE
PP3 or PP9 Clips. Pair 15p* El" Look at our Pak T Ten Plastic ALL FULL SPEC BRANDED
Power El 4000 1541'4001 4066 58p'
Din Plugs. All 19p BRIO° Mac 25p' 7400 Bp' 7475 44p
Or Pak C 4 I 203055 El 15p-- 4067 E4' TOP TWOSOME'
Die Sockets. All 10p C1060 44 400v SCA 55p" 7101 9p' 7476 35p
Disco Strobe Tile ES* TAG 1 400 lamp 55p' . Matching 2047 Ins Oil 10p 10p*
1002 179'- 4069 22p* 555 8 Pin Timer 27p
I
7402 1480 39p 741C Full spec OIL 8
DEVELOPMENT PAR- 600 65p° 4006 El* 4070 32p*
AC127 17p' BFY50 16p* 74(13 10p* 1481 El" 4007
MICRO POWER SUP- CELS. All ES each Switches Mini SPS1 55p* ACI76 10p, 8E451 16p
180'4008 4071 21p" Branded Op Amp INgs"
7404 17p* 1482 (1'- 92p*
PORT SET I: 250550 volt Ceramic Mini DPOT 69p'.. Centre off ACI87 20p' BFX29
4072 21p*
2847* 7405 9p" 7483 E1' 59p* NEW LINEARS Oata 10p
All full spec Grids I displays Capacitors 5'i. 10 each. 89p* 40161 Opp 85020 159* 7406 28p* 7485 El
4009 4073 2Ip*
DI.704 CC or 01707 CA 0.3" 4010 5$p' 4075 23p° 71170 Hall etlecl 69p*
From 22p1 to 0.1.1 E5 Slide Switch 25p* AF162 409- MJ2955 El 7407 280* 7486 35p
(1.25° 4011 15p" 4076 E1.29* U.071 Lo noise 741 75p'
SET 2: TanIalems lot to Push On' 35p AF239 42p- MJE340 44p 7408 12p* 7490 36p 4012 18p* TL081 FIT Bp. 741 699'
F110500 CC/161C 0.6" 200u1 20v to 35 volt. Total FULL SPEC PAKS ALL El BC107 Or MJE2955 Cl' 12p*
4077 40p*
7409 7491 75p 4013 55p' (1.49*
(1.25* 50 capacitors ES Pak A: 120 Red LEDS El* BC108 Bp* MJE3055 80p 10p* 7492
4078 21p' 11083 FET 747
7410 35p 4015 93p' 11080 FEE 748,308 E1.15^
MA864 Type/161A 0.6" SET 3: Electrolytic 25 velt Pak 8: 6 0 74IC 8 pin 9p
4081 22p°
BC109 MP11131 35p 7411 22p* 7493 35p 4016 52p°
(1.25* 10 each MO] 1/2/5/10/ El* 55p*
4082 21 p'
BC109C 5p 011P12 7412 22p* 7494 75p IC SUPERMARKET
E11.747 CA or 01 750 CC Pak C: 4o2 813055. TO 3
4017 99p* 4089 E1.50'
47/1001220/1000 ES 7413 26p* 7495 75p' 301 Op Amp 30p*
EI.69* SET 4: wall Resistors 5*. 4018 99p" 4093 85p`
B:E141917 111;210p:- ETTIIIPP4412A455 65p60pi 7416 28p* 7496 85p* 4020 El' 555 Timer 0165551 27p
Clock IC A951224 (3* C.F. 10 each 10 sits le 10 Pak D:12 x BC109 Et" 7417 211p* 74100 (1.15*
4507 550*
70p'
Display PCB 6 Digit 06" Et" meg ohm. Total 500. Belk Pak E: 13 x BC182 El BC157 15p T1P3055 50p* 7420 10W. 74107 29p°
4021 El 4508 Er 556 Dual 555
4022 4510 E1.35* 710 Comparator 40p'
LEOS. Bright lull spec. packed in 1 bo E5 Pak F: 13 x 2113704 El BCI58 15p 11543 35p 7423 26p* 74121 27p* 4023 20p 4511 E1.68* 723 Regulator 45p*
0.2" or 0.125" Red 10p* SET 5: Z eeeee 400mw 5 Pak G: 7 0 BFY Fl El . BCI59 15p 21264E 39p' 7425 26p* 74123 59p' 741C 8 Pin ON 094 19p'
12p* each. 20 values 3 volt le 4024 76p' 4512 glip'
711209 Red & Clip Poll H: 7 x 2113819 clot BC167 10p 2112905 22p° 7426 260* 74141 950* 741C T099 or OIL 14 39p'
4025 19p" 4514 E2.65*
0.2" Dim RN & Clip 12p* 33 volt (Total 100) ES El BCI68 lip 21129260 10p 7430 10p* 14143 (3.14* 4027 55p° 4516 E1.28' 7440 Op Amp 33p'
Yellow sr Grote 1000 SET 6: -100 Presets E5 New Pak I: 10 0 Metal BCI69 12p 2113053 16p* 7432 20p* 74145 85p* 4028 900" 4518 E1.05" 3900 Quad Op Amp 55p*
0.2" or 0.125" Dia. 41120p" SET 7: Heatsinks. 10 off, Trim. Knob ' dia (syn- BCI77 lip* 2113055 45p 7440 14p* 74141 (1.69* 4029 El ` 4520 E1.10*
7805 IAmp 5 volt 95p'
12 roll Fluorescent Lighl Each T018. T05. TY4 thesiser etc.) El* BC174 1164 - 2:33614 11 1441 79p" 74152 Er' 7805 T03(31190) El'
58p'
ES* )7099( end small TO 3 Pak J: 6 x 203053 El* 7442 87p* 74154 E' 4030
4032 El'
4521 E2.6(1"
4522 E2' 1808 or 7812 E1.25"
Jackson Tuner 37001 El ES* Pak K: 500194148 El BC182 10p 22,13704 9p 7445 69p* 74155 $0p* 7815 15 volt plastic 69p"
Trimmer 0-8 or 510 441 PASSIVE GEAR 4034 E2' 4528 99p'
Pak L: 50 0 330 10 volt 8C183 top 283706 9p 7446 811p* 74156 110p* 7900 Negative Series
4035 E1.20" 4534
25p Resisters 't watt Ya CF 2p electrolytic El BC184 top 2113819E 18p 7447 82p* 74157 El* E2.50*
4038 ELM" 4536 (3.60"
Coil Former & Slug 0.3" Dia Presets Type PR lied 10p Pak M: 4 0 Pairs Plastic BC212 12p 203820 3813 7448 Cl' 74164 El* 4040 E1.05* 4541 E1.511° 8038 Sig Generator 03.55"
Type 45 Pots Log 8 lie 25p Power tamp 60 volt. 8C213 12p 2113904 1SP 7450 15p" 74174 El' 4041 66p' 4543 Et 75' 76013 6 76023 (1.35
Relay WO 3 PM* 12 yell CAPACITORS NP1I/PNP 80131/2 Type 0(214 12p 2113906 15p 7451 15p* 74176 El' 4042 81p* 4553 (4.49' CA3I30 8 CA3140 94p*
Coil (l" Ceramic 50v 5..16 Stab 22p1 El 8E771 app' 2114347 50p 7453 15p* 74190 E2* 4043 96p' 4556 78p' LM3B0 I watt Amp 85p
RS Type Weeper 9 to 12v to 0.1ul8 .27/47 5p Pak N: 50 0 0481/91 El 80131 37p' 285457 32p 7454 15p* 74192 E2° 1111381 Dual Preamp E1.55
4044 95p 4558 E1.17'
(1.50* Tantalum Caps 12p Pak P: 20 s Plastic 109 80132 37p* 285777 44p* 7460 15p* 74193 (2* LM387 Oual Preamp El
4046 E1.30"

40'
4566 E1.59"
Oalo PC8 Pen 2 nibs 70p' ELECTROLYTICS 25 Yoh El 80695 6947" 71431 E2* 1470 29p° 74194 E.2* 55p*
4049 990' 4569 0.59" LM3900 Quad OPA
TUB Ferric (HL El* 1,10/47/100e All 10p Pak Q: 50 0 220ut 6.3v BD696 69p* TIL63 El" 7472 26p" 74196 (1.30" 52047 4583 ELIO' MC1310 Decoder El
Decoe Board CI RRRRR Pod 150 volt 20p) 220 or 470.1 Volt Eleclroltilic El DIODES & BRIDGE
7473 25p' 14191 £1' MC1460 1461 & 1469 E3*
4060 (1.15° 4585 £2.05'
50p* 30p Pak R: 14 0 BC107 El IA 50v Bridge 22p*
7474 29p" 74198 (2' 4063 E1.10" MCMOS 14433. A/0 ES°
604" Nylon/Copper Board 1000N 25 volt 35p Pak 5: 14 0 BC1011 El 184148 or 18914 4p' NE536 EFT OPA
60p* KNOBS. I" dia & trim 15p Pak T: Top selling 0481 or WWI NE555 Timer 27p"
5p
Vero Stocked All 10. oft HEAT SINKS. 105 8, 18 10 x NPN Plastic Power 60 04200 .9 207 100 OIL SOCKETS 8 pin 12p' 28 Pin EI NE556 Oual 555 70p*
i.e. 3'."15"00.1" Board 311" volt 2 amp 8081 Type 11140111 I4504 59' Low 24 Pin 50p 40 Pin E1.50 110810 7w AF El
56p* TV4 25p°. 703 small 25p' El 184004 7p*. WM 15p' Profile 14 or 16 Pin 15p 111414 Radio 65p

r --
PE SUSTAIN UNIT (P.E. OCTOBER 1977(

BUILD A SUSTAIN UNIT EQUAL TO THE

BEST COMMERCIAL MODELS.
COMPLETE KIT - 0.95
ALL HIGH QUALITY COMPONENTS
AS SPECIFIED.
DESIGNER APPROVED.

(id Complete set of semiconductors

O ir14 LP1186 Tuner Head
£4.99
£9.60

Become tuner Glass fibre PCB, printed with component

locations £2.45

a radio oar)*
amplifier
Complete set of semiconductors
Glass fibre PCB, printed with component
locations
£9.40

£3.50

amateur.
Learn how to become a radio -
PE DIGITAL VOLTMETER (APRIL 1977)
SPECIAL CLEARANCE OFFERS (while stocks last)
Set of semiconductor devices including all I.C..s, transistors,
amateur in contact with the whole diodes, regulators etc. but without displays. £13.508
world. We give skilled preparation Set of two professional grade printed circuit boards in
gloss fibre and printed with component locations. £1.95"
for the G.P.O. licence. Complete set of resistors, including attenuator resistors. £1.00*
WAA Complete set of capocitors, including 22000F power supply
1111 ZNA116 £6.00" with circuits. ZN7447A £1.00°. 78M05 regulator 15.52p5**.
E
Brochure, without obligation to: ZN423 £1.008.
PE TV SOUND SEPARATOR
BRITISH NATIONAL RADIO PEK1O Complete set of semiconductors £2.30. High quality glass fibre p.c.b. £1.00.
& ELECTRONICS SCHOOL, Murata filters: SFE6.0MA 35p. CD/06.0MC 35p.
P & P 15p per order. Orders over ES post free.
P.O.Box 156, Jersey, Channel Islands. All devices are top grade, brand new and to full manufacturer's spec. We do not
sell seconds or rejects. Send S.A.E. for our data sheet and price list.
NAME Prices do not include VAT -add 8% to items marked', and 124% to all
others.

ADDRESS DAVIAN ELECTRONICS op'pinotrnrenriocnlyllr.rs by

(Block caps pleasej
13 Deepdale Avenue, Royton, Oldham OL2 6XD
EWERS Tomorrow's Electronic Organ Kit is Here
POSSIBLY A NEW NAME TO
YOU, BUT KNOWN IN OVER 25
COUNTRIES FOR THE SUPERIOR
INSTRUMENTS WHICH THIS
GERMAN COMPANY PRODUCE

eh USED BY WEST GERMAN

%16P BROADCASTING SERVICE
PLAYED BY KLAUS
WUNDERLICH AND OTHER
FAMOUS ORGANISTS

Without doubt, the most

comprehensive kits and the most
GALAXY up-to-date designs available today.
The Flagship of the Just consider a few of the features
WERSI range of
Organs
Precision Master Generator, using MOS-LSI.
WERSI is the first kit producing Integrated electronic keying in I2L technology
company applying the latest
achievements of the space age Unique-All switch functions are program-
technology. mable.
This has decisive effects on the Even the smallest organ has drawbars in addi-
technical and musical quality of tion to fixed stops.
WERSI's electronic organs for the Craftsman -made cabinets available in 5 veneers
do -it -you rselfer. Ready-made wiring harnesses eliminate errors
The application of modern inte-
grated circuits, so-called IC's,
simplifies the organ construction Send now for the 104 page full colour catalogue
considerably. A single IC may and 16 page price list describing the 8 organs in
replace up to 10,000 conventional the range, together with the complementary kits
electronic components. In
addition, IC's save a lot of space which WERSI produce.
and they are extremely reliable
devices.
WERSI, however, went a step To: AURA Sounds, P1., Copthorne Bank, Crawley, West
farther yet. IC's which were not Sussex.
available on the open market were Please telephone to arrange demonstration 0342 713338
developed for specific purposes by I enclose £2.00, refundable against my first order to the value
WERSI engineering. They are £2500. Please send the Wersi catalogue and price list.
being produced by the most highly
reputed IC manufacturers in the NAME
world. The result: economical
electronic organs with the most ADDRESS
up-to-date techniques and unsur-
passed musical capabilities.

1043
Practical FlectronieN October 1978
 SEMICONDUCTORS POTS & IRONS
SOCKETS POTENTIOMETERS LEDs DISPLAYS & OPTOs
1611 8 pin OIL £0 13
1612 14 pin OIL VI 14 CARBON POTS (Linear Track) DUAL GANG LOG -ANTI -LOG POT 0/no. Type Size Colour Price
1613 16 pin ()IL EA 15 Single gang with wre end terminations 1888 Track specification as dual gang pots 1501 TIL209 led 125 RED £510
6mm 50mm plastic shaft 10mm bushes VC3 as above. but tracks mounted to log. 1502 TIL211 led 125 GREEN £019
1614 24 pin OIL £0 40 supplied with shake proof washer A nut. anti log action. 0 75 1503 TIL213 led 125 YELLOW £6 19
1615 28 pin OIL £0 45 Tolerance ± 20% of resistance 1504 FLV11S led 2 RED El) 111
1616 T018 Transistor £0 12 SPECIAL VOLUME CONTROLS 1505 FLV310 led 2 GREEN El) 19
1831 lb ohms LO 26' 1836 47kohms £0 26' A miniature 16mm type replacement 1506 FL V410 led YELLOW
1617 TU3 Transistor £0 35 1832 2k2ohms LO 26'1837 100kohms 0 26' volume control incorporating single pole
2 Ell 19
1510 BDL707 display 3 RED £0 80
16117 TO5 Transistor £0 12 1833 4k7ohms £0 26' 1838 220kohms £0 28' on -off switch. Resistance value 5kohms. 1511 BDL747 display 3 RED E1 50
1834 10kohms £0 26' 1839 470kohms £0 26' Tolerance ± 20% 1/8watt rating. 1512 BOL727 display 3 RED £1 SO
1835 22kohms £0 26' 1840 1Mep £0 26' 1839 £0 27' VC8 1514 ORP12 Light dependent
VOLTAGE 1841 2M2 £026'
MINIATURE ROTARY VOL resistor £0 SS
REGULATORS 1520 OCP71 Photo transs,stor El) 35
CARBON POTS (Log Track) CONTROL
Positive 5kohms log law with on/off switch. 20mm LED CLIPS
1842 4k7ohms E.0 211 1846 100kohms £0 26' grooved spindle. Tag connections 17mm 1508/125 pack of 5 125 clips £0 IS
MVR7805 v.a 7805 TO220 Et 00 1843 10kohms £0 26' 1817 220kohms £0 26' dia. Supplied with fixing nut. Used mainly 1508/2 pack of 5 2 clips £11 18
MVR7812 v.a 7812 TO220 £1 00 1844 22kohms £0 26' 1848 470kohms £028' for replacement.
MVR7815 v.a 7815 TO220 £1 00 1945 47kohms £0 26' 1849 1Meg £0 20' 1890 £0 54' VC9
1850 2M2 £0 21I 2nd GRADE LEDs
MVR7824 v.a 7824 T0220 E1 00 A pack el 10 standard sizes and colours which fail to perform
WIRE WOUND POTS to their very rigid specification. but which are ideal for
Negative DUAL CARBON POTS (Lin Track) A range of wire wound single gang pots
MVR7905 v.a 7905 10220 Ell 40 with linear tracks of watt rating, fitted
1
amateurs who do not require the full spec
These high rurality dual gang pots are fitted with 10mm bush and supplied with shake - 0/no. 1507 90p
MVR7912 v.a. 7912 TO220 E1 40 with wire end terminations and 6mm proof washer and nut.
MVR7915 v.a 7915 TO220 £1 40 50mm plastic shaft 10mm, bush and sup- VC6 NUMERICAL INDICATORS
MVR7924 v.a. 7924 10220 £1 40 plied with shake proof washer & nut track 1891 10ohms E0 80 1895 220ohms £0 80 Cold cathode ITT 5087ST Side viewing indicator tubes.
v.a. 723C 1099 45p Tolerance ± 20% but matched to within 1892 22ohms 0 1896 470ohms LO 110 Displays 019 and decimal points. Wide viewing angle.
72723 14 pin ON
2db of each other. VC3 1893 47ohins £0 BO 1897 Ikohme £0-80 Operates from 180v with 16Kohnis series anode resistor
45p
LM309K T03 E1 50 1851 41,7 £0 78' 1855100kohms £0 78' 1894 2 ()ohms Ell 80 1898 2k2ohms El) NI Character height 16 5nah Pin connectors and supply details
1 .5210kohms LO 78' 1856220kohrns £0 78 18994k7ohms £080 on pack
1853 22kohms £0 78' 1857470kohms LO 78 Dino. 1513. 5 for 600
1854100kohms L0711 1058 (Meg £0 78' PRE-SET POTS
ZENER DIODES 1859 2M2 78' HORIZONTAL MOUNTING
400mw (Bry881 DO7 Glass encaP Miniat.ire type for transistor circuits. The BRIDGE RECTIFIERS
sulated range of voltages avail- wiper of the preset is provided with a slot SILICON 1 amp
able 3v, 2 2v. 2 7v. 3 3v, 3 9v, DUAL CARBON POTS (Log Law) for screw driver adjustment. The tags of Type
1
1860 4k7ohms £0 78' 1864 100kohnis El) 711' the preset will fit printed wiring boards Order No. Price
4 3v. 4 7v. 5 Iv. 5 6v, 6 2v. 6 8v, 50V RMS BR1 50 £0 20
7 5v, 8 2v, 9 Iv, 10v. 11v, 12v, 13v. 1861 10kohms £0 78' 1865 220kohms El) 75' with a pitch ot 2 54mm All tracks are linear 100V RMS BRI/100 LO 22
15v, 16v. 18v. 20v. 22v, 24v. 27v, 1862 22kohms £0 78' 1366 470kohms EO 70' law. 200V RMS BR1/200
1863 47kohms £0 7$' 1867 Meg E0 711' VC7 £0.25
30v. 33v, 39v 400V RMS BR1 400 £036
No. Z4 8p ea. 1868 2M2 El) 70' 1801 100ohins£1108' 1808 22kohms 08'
1802 220ohms £0 08' 1809 47kohms LO OS' SILICON 2 amp
1w-1 Ow Plastic and metal encap- SINGLE GANG SWITCHED (Lin Law) 1803 470ohms £0 OS' 1810 100kohms £0 Or 50V RMS 892/50 £045
sulated Range of voltages
These potentiometers are fitted with 1804 1kohms 0.05' 1811 220kohms LO Or 10011 RMS BR2/100 £048
available 1 3v. 2 2v. 2 7v. 3 3v 1805 2k2ohms £0 OS' 1812 470kohms LO OS' 200V RMS BR2/200 £0.52
3 9v. 4 3v, 4 7v, 5 Iv, 5 6v. 6 2v double pole on -off switches. The switch is 1806 4k7ohms £0 011 1813 1 Mohms £0 08' 400V RMS BR2/400 1E0 511
6.8v, 7 5v, 8 2v, 9 Iv. I0v. 11v. incorporati.d within the rotary action of the 1807 10kohms f0 OS' 1814 2M2ohms £11 08' 1000V RMS BR2/1000 £0 68
12v, 13v. 15v. 16v. 18v. 20v, 22v. pot. Specification of pot is as VC1 1815 4M7ohms £001. 2 AMP METAL STUD MOUNTING
24, 27v. 30v. 33y, 43v. 47v. 51v. Switch rating Samos at 250v AC
1

No KI35005 50 volt £0 30
68v. 72v 75v. 82v. 91v. 100v 1870 4k7ohms 4060' 1874 100kohms 00 PRE-SET POTS No. KBSO1 100 volt £0 35
No. Z13 15p ea. 1871 10kohms E0 60' 1875 220kohms £0 60' VERTICAL MOUNTING No KBS02 200 volt £0 40
1872 22kohms E0 60' 1876 470kohms £0 00 Miniature type for transistor
circuits.
11)w Metal stud type 5010 case. Wiper adjustment is made by a screw
Range of voltages available, 1 3v. 1873 47kohms £0 60 1877 1Meg E0 60'
2 2v, 2.7v. 3 3v, 3 9v, 4 3v. 4 7v, 1878 2M2 60' driver slot. Designed to fit 2 54mm pitch THYRISTORS
5 1v, 5 6v, 6 2v, 6 8v, 7 5v. 8 2v, board. All tracks are linear law 600ma TO 18 Case 7 Amp TO 40 Case
VC7
9 1v, 10v, 11v. 12v, 13v, 15v, 16v SWITCHED POT (Log Track) 1816 100ohms £0011. 1823 22kohms £0 Oa' Volts No Price Volts No Price
18v, 20v, 22v. 24v. 27v. 30v 33v, Specification as VC2 but track having (log) 1817 220ohms EO 00' 1824 47kohms EO Or 10 THY600 10 £0 15 50 THY7A 50 £0 48
43v. 47v. 51v. 68v. 72, 75v. 82v, law. 1818 470ohms £0 OS' 1825 100kohms £008' 20 THY600/20 £0 16 100 THY7A/100 £0 51
91v, 100v. 1879 4k7ohms £0 60' 1833 t00kohms El) 60 30 THY600/30 £0 20 200 THY7A1200 £0 57
No. 210 350 ea. 1819 Ikohms £0 011 1826 220kohms LO 00'
1880 10kohms £0 60' 1884 220kohms £0 60' 1820 2k2ohms £0 OS 1827 470kohms £0 OS' 50 THY600/50 £0 22 00 THY7A/400 £0 62
1881 22kohms £0 60' 1885 470kohms Ell 60' 1821 4k7ohms Or 1828 1M ,gohms£0 00 100 THY600/100 £0 25 600 THY7A,'600 £0 78
1882 47kohms E060' 1886 1Meg LO 60' 200 THY600/200 600 THY7A X800 £0 92
SILICON 2M2 EO 60'
1822 10kohms E0 Or 1829 2M2ohms LOOS
1830 4M7ohms £0 011. 400 T H Y600/400
LO 311
£0 44
RECTIFIERS 10 Amp TO 48 Case
200mA
S920 50v £0 06 ANTEX IRONS 1 amp TO 5 Case
Volts No Price
5921 100v £0 07 0,No 1943 15 watt high quality soldering 50 THY10A,50 £0 51
E0 03
0:No. 1931 Highly popular "25 25 watt Volts No Price 100 THY10A,100 £0 57
S922 150, iron totally enclosed element in a ceramic Quality soldering iron ceramic shafts to THY10.4,200 £0 62
S923 200v £0 09 50 THY1A 50 £0.26 200
£0 10 shaft fitted with 3/32" bit £3.80 provide near perfect insulation break -down 100 THYIA.100 £0 25 400 THYIOA/400 £0 71
5924 300y voltage of 1500 volts AC and a leakage THY10A,600
Amp 200 THY1A/200 £0 32 600 £0 99
0/No. 1947 Replacement element for 1943 current of only 3-5uA and another shaft of 400 THYIA,400 £0 36 800 THY10.411300 Et 22
N4001 50v LO 04) iron stainless steel to ensure strength. E3.60
N4002 100v £0 05 £1 90 600 THY1A/600 £0 45
N4003 200v 0 06 0/No 1944 Iron coated bit 3/32" for 1943 O/No 1935 Replacement element for 1931 800 T HY 1A/ 800 £0 58 16 Amp TO 40 Case
N4004 400v £0 07 iron iron. £160 Volts No. Price
£0 45
N4005 600v £0 00 0/No 1932 Iron coated bit 1/8" for 1931 SO 71-1Y16A 50 £0 54
N4006 800v £0 09 OeNo 1945 Iron coated bit 1/8" for 1943 iron £0 50 3 amp TO 66 Case 100 THY16Ai100 £0 5$
N4007 1000v £0 10 iron £0 46 Volts No Price 200 THY16A;200 £0 62
0/No 1933 Iron coated bit 3/16" for 1931
0/No 1946 Iron coated bit 3/16" for 1943 iron £0 SO 50 THY3A/50 ED 211 400 THY16A/400 EA 77
5 Amp THY3A/100 £0 30 600 THY16A1600 0 90
5015 50v EP 09 iron ED 46 0/No 1934 Iron coated bit 3/32" for 1931 100
£0 10 iron 200 THY3A/200 £0 33 800 THY16Ai800 E1 39
S020 100y 0/No. 1948. General purpose 18 watt iron £0 50 400 THY3A/400 £0 42
5021 200v £0 11 0/No. 1953. SKI soldering kit -this kit con-
S023 400v £0 13 fitted with iron coated bit. £3.60 600 THY3A/600 £0 50 30 Amp TO 94 Case
tains 15 watt soldering iron fitted with a 800 THY3A/800 £0 65
S025 600v f13.14 0/No 1952 Replacement element for 1948 3/16" bit plus two spare bits, a reel of Volts No Price
S027 890v £0 16 iron £1 90 solder, heat -sink and a booklet 'how to 50 THY30A/50 £1 18
S023 1000v £0 20 solder' to presentation display box. £5.55 100 THY30A/100 E1 43
5031 1200v £0 25 0/No 1949 Iron coated bit 3/32" for 1948 5 Amp TO 66 Case 200 THY3041)/200 £1 63
iron £0 46 0/No 1939. ST3 soldering iron stand. Volts No. Price 400 THY30A /400 E1 79
3 Arno Stand made from high grade bakelite 50 THY5Ai50 £0 36 600 THY30,4/600 E3 50
IN5100 50Y £0 14 0/No 1950 Iron coated bit 1/8" for 1948 material chromium plated strong steel 100 THY5A,100 0 45
IN501 100v £0 15 iron £0 46 spring, suitable for all models, includes
IN5902 200v £0 16 200 THY5A/200 £0 50 No Price
0/No 1951 Iron coated bit 3/16" for 1948 accommodation for six spare bits and two 400 THY5A:000 £0 57
IN5409 400v £0 17 sponges which serve to keep the soldering BT101'500R E0 80
IN5103 6302 £0 21 non £0 46 600 THY5A/600 £0 89 131102500R £0 80
iron bits clean. £1,50 800 THY5A,800 £0 81
I N5407 800v £0 25 BT106 £1 2S
IN5108 1000v £0 30 BT107 £0 03
0 Amp
T R120
£1 19
T R101
£1 10
TR053
£1 10
TR203
£1 10
TR205 PCB TRANSFERS 5 Amp TO 220 Case BT108 CO 91
Ell 70
o0
£1 10 2N3228
S10,50 50v £0 19 Volts No. Price 2N3535 £11 77
£0 21 0 TR114 TR312
510/100 100v
S10/200 200v £0 23 0 £1 65 £1 10 400
800
THY5A,400P
THY5A/600P
£0 57
LO 69
BTX30,50L
BTX30,400L
£0 33
LO 45
S101400 400v £0 35 I RI., 1-< .31
000000000000 800 THYSA/800P LI) 81 C106.4 £060
510/600 600v £0 42 Cl 50 £1 65 £1 75
S10/800 800v £0 51
£0 60 0000 0000000 00000000
.0e TF3,5
S10/1000 1000v 0 0 £1 95 ORDERING. Do not forget to state order num-
S10/1200 1200v £0 69 000
34 Amp 0000 0000900 00090000 000000000000 ber and your name and address.
S30/50 50v £0 56 Draw your own boards with the new BI- etch -resist pen. 11 different paks available
S331100 100v £0 69
PAK etch -resist transfers. Lay the symbols each containing 10 sheets of transfers as V.A.T. Add 121i% to prices marked. 8% to
S30/200 200v £0 93
S30/400 400v £1 25 on the board. rub over with a soft pencil. illustration-approx. size -Special those unmarked. Items marked are zero rated.
S30/600 600v £1 76 The transfer will adhere to the board. Then Introductory Set. 1 pak each of above
033/800 800v £1 94 complete the circuit with your 61-PAK £12.00.
S30/1000 1000v £2 31 P&P 35p unless othr,rwise shown.
S30/1200 1200v £2 88
60 Amp
S70/50 50v £0 75 930 SERIES DTL D.I.Y. P.C.B.
070/100 100),
570/200 200y
570/400 400v
S70/600 600v
S70/800 800v
S70 1000 1000v
BYX39!300 6A 300v
BYX31311300 6A 600v
BYX381300 Rev 6A 300v
El) 84
£1.20
E1 75
£2 25
E2 50
£3 00
£0 45
£0 60
£0 45
BP930 £0 30
BP932 £0 30
BP933 £0 30
BP935 £0 30
BP936 £0 55
8P948 £0 50
BP95I £0 65
BP962 £0 30
BP9093 £0 42
BP9094 £0 42
BP944 0 30 BP9067£0 42
BP945 LO 50 9P9099 £0.42
ACCESSORIES
1609. Etch resistant pen
1608. Paks of etchant, complete with
instructions
CM 4 pieces 8 31" (approx.) boards.
Single -sided fibre glass
C27. 3 pieces 7
80p
31" (approx.) boards.
65p
sop IN-PAK
DEPT. PE10, P.O. BOX 6, WARE, HERTS.
BYX38/600 Rev 6A 600v £0 60 BP946 £1) 30 Double -sided fibre glass flOp SHOP 18 BALDOCK ST., WARE, HERTS.
AT OPEN 9 to 5.30 MON-SAT.

1(114 Practical Electronics October 1978

 SEMICONDUCTORS
TRANSISTORS 74 SERIES TTL IC'S
Price Type. Price Type Price Type Price Type Price Type Price Type Price Type Price
Type Price Type Price Type Price Type
2N2926Y CO OS' 7427 E1 24 7472 £1) 20 74105 LO 38 74163 LO 78
£0 16 ZTX107 LO 10' 7400 Et 10
LO 22 BC125 E0 17* BD185 £0 68 BSY26 7428 Ell 33 7473 £1) 2S 74107 CO 27 74164 £0 OS
AC107 £0 16 ZTX108 £0 10' 21129260 £(1 0111' 7401 £11 11
£0 20 BC126 EO 22 BD186 £0 88 BSY27 2N2926R £0 08' 7430 Ell 12 74110 £11 45 74165 £0 85
AC113 BSV28 E0 16 ZTX109 LO 10' 7402 CO 11 7474 LO 2S
P.C115 £0 20 BC132 E0 111. B0187 £0 75 2N2926B LO 011. 7403 CO 11 7432 LO 22 7475 £1) 29 74111 El) 67 74166 £1) 95
£0 111. BD188 £0 75 SSV29 £0 16 ZTX300 E0 12* LO 80 74174 £0 86
AC117 £0 AO BC134
130538 LO 19 £1) 12. 2113010 £0 65 7404 El) 11 7433 £0 30 7476 £0 25 74118
AC117K 1.0 34 BC135 Ell 15* BD189 £0 78 ZTX301 LO 15 7405 CO 11 CO 23 74119 El 18 74175 £066
BSY39 £0 19 £0 16' 2113011 7437 7480 ES 44
AC121 £41 20 BC136 £0) Ir BD190 £0 78
LO 29
ZT X302
2N3053 E016 7406 E0 20 7438 £0 23 7481 £0 85 74121 E0 24 74176 £0 74
£0 14 BC137 E0 18. B0195 £0 90 BSY40 ITX303 E0 16' £0.26 £0 75
AC122 BSY41 LO 29 £11 20 2113054 E0 40 7407 7440 E0 12 7482 E0 68 74122 £1) 39 74177
AC125 £0 18 BC139 £0 32 BD196 £0 90 ZTX304
£0.40 7408 LO 13
£0 30 BD197 CO 95 50451 LO 25 ZTX330 LO 15' 2N3055 7441 E0 SO 7483 E0 70 74123 CO 46 74180 £0 84
AC126 £0 IS BC140
BSY95 £0 13 211339I £0 20 7409 Ell 13 7442 E0 SI £0 88 74136 £0 74 74181 £1 60
AC127 £0 10 BC141 £028 B0198 £0 95 ZT 0500 E0 14' 7410 12
7484
80199 £9 99 BSY95A LO 13 E0 12* 2N3391A £0 22' Ell
7443 £088 7485 £0.25 74141 £0 55 74182 £0 74
AC128 £0 IS BC142 £0 22 ZTX501 El) 20' 7411 £0 17 LI 18
LO 22 B0200 LO 99 BRY39 £0 45 ZTX502 E0 16* 2113392 7444 £088 7486 £0.88 74145 £0 62 74184
AC128K £0 26 BC143
BU105 £1 40 2N3393 £0 20 7412 Ell 20 £0 65 74150 £0 OS El 00
AC132 £0 20 BC145 £0 46 BD201 £0 80 ZTX503 E0 12* LO 24
7445 7489 £1.95 74190
£0 Or BD202 EO 80 BU105IO2 £1 95 ZTX504 E0 45' 2113394 £0 20 7413
7446 V/ 65 7490 £0.32 74151 £058 74191 £1 00
AC134 £0 20 BC147 £1 70 E0 22' 7414 £0 SO £0 95
BC148 El) 0/1 - B0201'202 £1 70 BU204 ZTX531 E0 26* 2113395 7447 £0.60 7491 £064 74153 LO 58 74192
AC137
AC141
ES 20
£0 22 BC149 Or
E0 20'
50203
BD204
£0 80
EO BO
BU205
BU208
LI 70
£2 25 ZT X550 £0 16. 2113402
2N3403
£0 21'
£0 21'
7416
7417
CO 29
Ell 26 7448
7450
£0.56
£0.12
7492
7493
£0.37
£030
74154
74155
£0 95
£090
74193
74194
LI 00
E0 89
AC141K £0 30 BC150 BU2113'02 E2 95 £.0 29' 7420 V) 12
AC142 £0 20 BC151 E0 22 BD203 204 £1 70 2113404
7421 £0 20 7451 £11 12 7494 £075 74156 £0 60 74195 £0 82
E0 20' 50205 E0 80 20301 E0 22 2113405 £0 42. Ell 12 £0.50 74157 LO 60 74196 £089
AC142K £0 30 BC152 £016 7422 £0 14 7453 7495
AC151 £0 20 BC153 LO 25' 80206 £0 80 E1222 LO 38 20302 £0 22 2N3414
7423 £0 23 7454 LO 12 7496 £0.82 74160 £0 78 74197 £0 85
£0 22 BC154 £0 19. 00207 £1 00 20303 £0 22 2113415 £0 16' £0 12 74100 £0.92 74161 £0 71 74198 El 45
AC153 £1 00 £0 29' 7425 El) 19 7460
AC153K £0 30 BC157 El) 10 BD208 20304 LO 30 2113416
7426 CO 23 7470 £0 25 74104 El) 39 74162 £0 78 74199 El 45
BC158 £0 10. B0222 E0 47 MAT100 E0 19 20306 £0 40 2N3417 EO 29
AC154 E0 20 £0 47 E0 20
AC155 £0 20 BC159 £0 10. BD225 MAT101 20308 £0 36 2113614 £1 00
AC156
AC157
4C165
£0 20
£1) 25
£0 20
BC160
BC161
BC167
E0 32
£038
LA 12*
BD232
B0233
130234
LO 55
£0 48
MI 55
MAT120
MAT121
MJ480
£0 19
LO 20
LO 95
20309
20339
20339A
Ell 36
£0 20
£0 18
2113615
2N3616
2113646
LI 05
£1 05
El) 09'
CMOS ICs
BC/235 £0 55 MJ481 E1 OS Type Price Type Price Type Price Type Price Type Price
AC166 £0 20 BC168 £0 12. 20344 £0 20 2N3702 £0 08' CD4026 LI 70 CD4043 £0 98 CD4070 E0 40
E0 20 BC169 £0 12- B0236 £0 59 MJ490 LI) 95 £0.13. CD4000 £11 IS CD4015 £0 98
AC167 £0 55 £1 IS 20345 1.0 18 2113703
CD4016 £0 SO C04027 £0 60 CD4044 VI 94 CD4071 El) 23
AC168 £0 25 BC169C E0 14. BD237 MJ491 2113704 £.0 07' CD4001 E018
BD238 £0 60 MJE340 El) 45 20371 CO 18 C134002 £0 18 CD4017 LO 98 C134028 £0 98 C04045 El 40 CD4072 £0 23
AC169 £.0 20 BC170 £0 10' 203715 40 12 2N3705 £0 07 CD4029 £1 15 1 134046 £1 30 C04081 LO 20
MI 25 BC171 £0 10. BDX32 £2 20 MJE370 £0 68 2N3706 £0 08' C 34006 £0 98 CD4018 Et 00
AC171 E1 30 El) BO 2G373 40 11 CD4030 £0 55 C04047 El 10 CD4082 El) 23
AC176 £0 IS BC172 £0 10' B0411 MJE371 2113707 £11 Or CD4007 £010 CD4019 £0 SS
BDY17 EI 80 MJE520 E0 65 20374 £0 18 CD4008 E0 98 C04020 El 10 CD4031 E2 20 CD4049 £0 55 CD4510 £1 30
AC176K £0 26 BC173 £0 12. Ell 72 20377 £0 32 2113738 LO Or CD4035 £1 30 CD4050 £0 55 CD4511 £1 60
£0 15. BDY20 80 MJE521 21437084 £0 07' CD4009 £0 SI CD4021 ECI 98
AC178 £0 25 BC174
E0 90 MJE2955 E098 20378 £018 CD4022 £0 00 CD4037 £0 95 CD4054 £1 10 CD4516 EI 40
AC179 £0 25 BC175 35 BDX77 2113709 £1) or CD4010 £0 58
E.0
8E115 £0 22 MJE3055 LO 60 20381 E0 11 C04011 £0 20 CD4023 E0 20 CD4040 LO 95 CD4055 LI 40 CD4518 £1 25
ACI80 20 BC177 £0 16 £0 S2 2N3710 Ell 07' C04041 E.0 112 CC4056 £1 35 CD4520 £1 2S
AC183K £0 24 BC178 £0 16 8E117 E0 SO MJE3440 20382 Ea IS 2143711 £0 Or CD4012 £0 20 CD4024 LO 80
£0 16 8E118 £0 75 MP8113 £0 52 20401 £0 32 CD4013 CO S2 CD4025 £0 20 CD4042 £0 112 C04069 £11 40
AC181 £0 20 BC179
8E119 E0 75
2143772 LI 60
AC181K £0 20 BC1130 £0 25 20414 £0 32 2113773 £2 50
£0 25' 8E121 £0 50' MPF104 £0 38 20417 E026
AC187
AC187K
AC188
El) 18
£0 24
E0 10
BC181
BC182
BC182L
El 10'
£0 10'
6E123
BF125
6E127
MI 60'
LO 50'
£0 60*
MPF105
MPSA05 £0 30'
MPSA06 CO 30'
El) 30 2113819
2N3820
2113821
£0 20
£0 35
£0 60
LINEAR ICs
AC11388 £0 2d BC183 £0 10' 2N308 £0 36 2N3821 LO 60 Type Price Type Price Type Price Type Price Type Price
BF152 £0 25' MPSA55 E0 28* E0 56
ACY17 £0 31 BC183L £0 10"
BF153 E0 25' MPSA56 EO 28*
2N388A 2113903 E0 15 CA3011 EI OS' LM301 EO 39' MC1456 £11 40' 709P £0 25' SN76115£1 90'
ACY18 £0 26 BC184 £0 10' BF154 El) 22' ND120 £0 111 2N404 £0 20 2N3904 £11 15' CA3014 LI 70' LM304 60 MC1466 £4 SO UA710C £0 40' SN76660£0 75'
ACY19 £0 25 BC1841. £0 10. £0 35 2N524 £0 40 2N3905 £0 15' CA3018 £(1 75' LM308 LI 40' MC1469 £2 05 74710 E0 30' SL414A El 911'
£0 24 £0 22 8E155
AC Y23 BC186 8E156 £0 28 2N527 £0 50 2113906 LO 15' CA3020 £11 70' LM309 LI SO MC1496 £0 ft' UA711C £0 32' TAA550B
AC Y21 £0 20 BC187 £0 22 BF157 £0 28 0C19 £0 115 2N598 £0 40 2N4058 £0 12' CA3028 El 02' LM320-5v £1 SO NE536 £3 50' 72711 LO 32' £41 35
AC I22 £0 26 BC217 Ell 11. BF158 35' 0C20 VI 85 211599 £0 46 2114059 £0 14' CA3035 £1 70' LM320-12vE1 SO NE540 L1 50' UA723C EO 45 TAA621A
AC.Y27 EU 24 BC2D8 LO 11* £.0 14 CA3036 £1 35 LM320-15v£1 50 NE550 £1) 95 72723 £0 45 £2 CO'
AC Y28 £0 21 6E159 £0 35' 0C22 £1 SO 2N696 £0 13 2144060 £0 32 UA741C £0 24' TAA621B
BC279 £0 12' 8E160 £0 30' 0C23 El SO 2N697 £1) 12 2144061 £.0 12' CA3042 £1 50' LM320-24v£.1 SO NE555
AC Y29 £0 35 BC212 £0 11. 13E162 £0 30' 0C24 El 35 fIl 12 2144062 £0 12' CA3043 L1 115' LM380 E0 85' NE556 £0 82 72741 £0 24' £2 SO'
ACY33 £0 25 2.4698 £3.95 741P £0 20' TAA661 E1 65'
BC212L £0 11 8E163 E0 30' 0C25 LI 00 211699 LO 32 2114284 E01$' CA3046 £1) 80' LM381 £1 55' NE561
AC Y31 £1) 25 BC213 £0 11. 8E164 £0 SO' 0C26 LI 00 2114285 £1) 18' CA3052 £1 60' LM3900 El) 65' NE562 £3 115' UA747C 70' TAD100 LI 30'
AC Y34 £0 25 BC213L £011 E0 80 211706 CO 10
£0 18' CA3054 LI 35' MC1303LEI 48 NE565 £1 75' 72747 £0 79' TBA540 £2 20'
ACY35
ACY36
£0 25
E0 35
BC214
BC214L
EO
£0 12'
Ir 81165
BF167
LO SO'
LO 24
0C28
0029 £0 95 2N706A
214707
£0 12
£0 40
2114286
2114287 £0 18' CA3075 El 50' MC1304 £1 90' NE566
CA3081 LI SO' MC1310 £11 95' NE567 £1 80' 72748
LI 50' UA748
£0 35' T8A810 £1 05'
£0 35 TBA800 LI) 80'
BF173 LO 20 0C35 £0 90 E0 14 2114288 E0 10'
AC Y40 £0 22 BC225 £0 26. 8E176 £0 3/1" 0C36 El) 90 2N708
2N4289 £1) 18' CA3089 E2 16' MC1312 £1 90' UA7C2C £0 46' 748P £0 35 TBA820 LO 110.
AC Y41 E0 25 BC226 £0 36' ElF177 £0 26 0C41 £0 20 2N711 £0 30 2114290 £0 111' CA3090 £4 25' MC1330 £1 20' 72702 £0 46' 5647601311 7849200£3 40'
AC Y44 £0 24 BC227 £0 16" BF178 29 0C42 £0 22 211717 £0 30 2114291 £0 111' CA3123 £1 90' MC1350 CI 20' UA703 £0 25' £1 75' TCA2705
AD130 £0 70 BC238 £0 16' £11 30 0C44 £0 24 2N718 £0 25 2N4292 LO 10' CA3130 £0 93 MC1351 £1 20' UA709 LO 25' SN76023£1 75' £2 20'
BF179 £0 46' SN76110£1 50'
A0140 £0 60 BC251 £0 15 BF180 £0 30 0C45 LO 20 2N718A £050 2N4292 £0 10' CA3140 £0 90 MC1352 £1 40' 72709
AD142 £0 05 BC251 A E0 16' BF181 £0 30 0070 E0 24 2N726 £0 29 2114921 £0 55
AD143 £1) 75
BC301 £0 28 BF182 £0 30 0071 £015 214727 £0 29 2114923 £0 65'
40149
40161
AD162
£0 60
£0 42
£0 42
BC332
BC303
£0 28
£0 28
8E183
BEIM
£0 30
El) 20
0072
0074
£0 24
E026
211743
211744
£0 20
LO 20
2N5135
2115136
£0 10'
£0 10'
DIODES
BC304 £0 38 BF185 E0 20 0075 £0 30 211914 £0 15 2115138 £0 10' Price Type Price Type Price Type Price Type Price
A01611162 £0 05 Type
BC327 £0 16' 6E186 £0 26' 0076 E0 35 211918 £0 30 2115172 E0 14. AA119 E0 CO BAX13 £0 07 /34164 £0 51 0410 £0 35 SD10 £0 06
A01140 y El) 55 BC328 £(1 15' E3F187 £1) 26 0077 £0 SO 211929 EA 20 2115194 El) 56 BAX16 £0 OS 84176 El) 75' 0447 E0 OS 5019 £0 06
AF114 £0 40 £0 22 AA120 £0 08
BC337 £015' 13E183 0081 2119,0 £0 IS 2N5245 El) 43 AA129 £0 08 85100 £0 22 134206 £0 30 0470 £0 00 11134 £0 07
A1115 £0 21 BC338 £0 15' 6E194 £010' 0081D £0 24 261946 LO 40 2115294 E0 34 BYZ10 El) 45 0A79 £0 13
A1116 £0 21 0082 LO 24 AAY30 £0 09 BY101 £1) 22 IN34A £0 07
BC140 £0 30 BF194 £0 10' 2147131 £0 18 2N5296 LO 36 AAZ13 £0 IS 84105 £0 22 BYZ11 £0 45 0481 EC 13 111914 £0 05
A1117 El) 21 £(1 10' 00820 £0 30 £0 18 £0 32 BYZ12 £0 45 0485 £0 13
AF118 £0 40 BC441 £1) 30 8E196
E0 26
2111132 2115257 BAJO° £0 10 134114 £0 22 IN916 E0 06
BC460 £0 311 BF197 £0 12' 0083 2141302 £0 15 2145458 £0 32 BA102 £0 32 134124 MI 22' BYZ13 £0 40 0A90 E0 07
A1124 £0 30 BC461 E0 311 13'193 LO 14' 0004 £0 33 2741303 £0 10 2115459 LO 35 84148 £0 15 85126 £0 15' 85115 £0 41 0.491 £0 07 IN4148 E000
41125 LO 37 BC477 £0 20 BF199 £0 14* 0C139 £.1 20 2117304 £0 10 2N5551 £0 36' 84154 E0 12 55127 £0 16' BVZ17 £0 36 0A95 El/ 07 154.1 £0 OS
AF126 £0 30 BC478 £0 20 8E200 £0 30 0C140 £1 15 2111305 EA 18 £0 34 BA155 EA 14 84128 £0 16 BYZ18 £0 36 04152 LO 13 15920 £006
AF127 £0 32 LO 35 2116027
BC479 £0 20 ESF202 CO 90' 0C169 2111306 £0 25 2N6121 £0 70 BA173 £0 15 65130 £0 17' BYZ19 £0 36 04200 £0 01
41139 £0 35 BC547 £0 12' 8E222 £0 90 0C170 £1) 35 2111307 £0 25 £13 70 BB104 El) 15 BY133 £0 21' OAS E0 60 0 4202 £0 08
E0 60 V) 35 2116122
AF178 BC548 £0 12' SF224 £0 17 0C171 2111306 £0 30
AF179 EA) 60
BC549 £0 12' BF240 £0 17. 0C200 £038 2N1309 £0 30 TRIACS
A1180 E0 60 £0 14' BF241 £017' 0C201 1E0 05 2.41599 £1) 35
AF181 CO58 8C55? LI 20 2S 301 £0 50 2 amp TO5 Case 10 Amp TOO Case
BC556 £0 14' 8E214 £0 30' OC202 2111613 ES 20 25 302 LA 43 Price
AF186 £0 50 £0 13' 8E257 £0 30 OC203 E0 85 2741711 £0 20 Volts No Price Volts No
41239 £0 38 BC537 £11 90 25 3024 £0 43 TR110o100 £0 77
BC558 £0 12" 131258 E0 30 0C204 2111689 £0 45 25 303 £0 56 100 TR12a:100 E0 31 100
ALM El 20 BC559 14. 8E259 £0 42 0C205 LI IS 2141890 E.0 45 25 304 £0 71 200 TR12a;200 £0 51 200 TR100a,200 E0 92
AL103 £1 18 £0 59 BF262 £0 69' 2741893 £030 £0 80 400 TR12a/400 £0 71 400 TR100a0400 £1 12
ASY26 £0 38 BCY30 2S 306
BC431 £1) SS BF263 £.0 60' P346A £0 35 242147 E0 75 2S 306 £0 BO
ASY27 LO 40 £0 64 BF270 LO 36 £0 45 2112148 El) 70 10 Amp TO220 Plasttc Case
ASY28 130432 P397 2S 307 LO BO 6 Amp TO66 Case
30
BCY33 £0 55 31 2112160 LI 00 25 321 ED 57 Price Volts No Price
ASY29 30 £0 80£0 Volts No
AS450 £0 30 BC431 £0 60 8BE272F271
2h12192 £0 38 2S 322 £0 43 100 TR16a/100 £0 51 400 TR110a 400p £1 12
BCY70
is BF273 Ell 36* R20008B £2 SO 2112193 £0 38 2S 322A E0 43 TR16a/200 £1) II DIACS
ASY51 £0 30 8E274 £0 3V R231013 £2 60 £0 38 £0 57
r 230
AS452 £0 30 BCY71 £0 IS 2112I94 25 323 400 TR16a4100 £0 77 138100 £0 20 D32 £0 20
BCY72 £0 14 13E324 £0 35' 2112217 £0 22 2S 324 £0 71
ASY54 E0 30 13E336 LO 35
AS455 £0 30 BCZ10 CO GO 5T140 LI) 15 2N2218 £0 22 25 325 £0 71
SF337 £(1 30' £0 71 ORDERING
ASV56 1£0 30 BCZ11 £0 60 6E336 £0 36 ST141 E0 20 2.122184
2N2219
E0 20
£17 20
25 326
25 327 £0.71
BI-PAK CATALOGUE
AS457 E0 30 BCZ12 El/ 63 ElF457 LO 37 e.3 :4
Do not forget to state order NEW EDITION NOW AVAILA9I E
ASY58 £0 30 2N22I9A number and your name and
80115 £0 SO BF458 LO 37 TIC44 £0 211' 2712224 £0 20
ASY73 £0 30 80116 80 8E459 £0 38 TIC45 LO 35 £0 20 and address Send fur your copy of out revised 3atalogue
£1 40 2(12221 40311 £0 38
AU104 BD121 £11 63 BF594 El) 30' TIP29A £0 40 2h/2221A £0 22 40313 £0 95 and price list NOW' It contains 127 pages
AU110 £1 40 00123 VI 65 BF536 or TIP2913 £0 52 2112222 £0 20 40316 LO 95 V.A.T. Packed with literally hundreds of semi.
AU113 El 40 B0124 E0 70 BER39 £0 24 TIP29C CO 50 2112222A £0 20 £0 40 Add 121% to prices marked
80131 El) 38 BER40 £0 25* TIP30A E0 50
40317 conductors components and our tempos
£0 40 £0 28' 2142368 LO 10 40326 E0 40 8% to those unmarked Items range of BI -KITS audio modules
50132 BFi479 TIP3013 £11 60 2142369 £0 IS 40327 LO 45 marked 1 are zero rated
BC107 £0 03 80131 132 £0 85 BE989 £0 211. TIP30C 61) 21123694 LO 14 £0 45
40346
BC107A £1) 08 1313133 £0 40 BFX23 £0 22 T1P31A £0 45
BC107B £0 08 50135 LO 34 BFX30 £0 30 TIP31B £0 47
2112411
2742412
E0 25
£11 25
40347
40348
E0 65
E0 80
P&P ONLY 65p POST FREE
BC107C El) 03 80136 £0 3S BFX84 £0 22 TIP31C E0 49 242646 £0 47 40360 £036 35p unless otherwise slated
8C108 £0 08 BD137 CO 35 BFX85 £0 24 TIP32.44 al 49 2,42711 £0 22 £0 36
£0 08 40361
BC108A 1313138 LI) 40 13F)(85 £(1 2S TIP32B £0 51 2N2712 E0 22 Ell 38
£0 08 El) 34 VI 22 40362
BC108B BD139 BFX87 TIP32C CA 53 212714 £0 22 40406 £0 45
BC108C £0 08 80140 LO 36 BFX88 £0 22 TIP41A £0 49 EO II
£0 08 2112904 40407 E0 35
BC109 BD139/140 E0 82 BFX90 £0 SS' TIP4IB CO 51 £0 21 40408 52
£0 08 £0 16 2142334A El)
BC109B 80155 E0 80 81550 TIP41C £0 53 2112905 £0 18 40409 El) 75
BC109C £0 00 130175 £0 SI BEY51 E0 16 TIP42A £1) 53 2112305A E0 20 40410 £0 TS
BC113 £0 111* 80176 E0 80 BF552 E0 16 T1P42B £0 55 £0 16 £2 70
£0 11 2112306 40411
BC114 BD177 £0 00 BFY53 14 TIP42C Ell 57 21123064 £0 19 40430 El) 95
BC115 £0 19' 501713 LO 61 BIP19 EO 3$ T1P2a55 £0 65 2 N2307 ES 20 40476 £1 SI
BC116 LO 19' 80179 E0 75 BIP20 £0 311 TIP3055 £0 SO E0 22 40494 E0 TO
Ell 19* E0 7S BIP19 20 E0 00 21129074
BC116A 130183 T1543 LO 24 £015 £0 80
BC117
8C118
£0 20'
£0 14.
50181
B0182
LO n BPX23
El) 00 BS)(19
EI 45
£0 IS
TIS90 LO 22'
2112923
2N2924 CO 15
40495
40512 El 35 DEPT. PE10, P.O. BOX 6, WARE, HERTS.
BC119 EO 20 BD183 E0 OS BSX20 CO IS 2N2925 El) 15' 40594 LO 00
BC120 El) 40 80184 E1 10 BSV25 E016 UT46 £0 22 2N29260 E0 09. 40636 CI 10
SHOP 18 BALDOCK ST., WARE, HERTS.
AT OPEN 9 to 5.30 MON-SAT.

1045
Practical Electronics October 1978
 KITS FOR SYNTHESISERS, SOUND EFFECTS
COMPONENTS SETS include all necessary resistors.
capacitors, semiconductors, potentiometers and
transformers. Hardware such as cases, sockets, knobs,
keyboards. etc. are not included but most of these may
be bought separately. Fuller details of kits, PCBs and
parts are shown in our lists.
PHONOSONICS
MAIL ORDER SUPPLIERS OF QUALITY
CIRCUIT AND LAYOUT DIAGRAMS are supplied
free with all PCBs unless -as published'. PRINTED CIRCUIT BOARDS KITS AND
PHOTOCOPIES of P.E. texts for most of the kits COMPONENTS TO A WORLD-WIDE
are available -prices in our lists. MARKET

P E MINISONIC Mk. 2 SYNTHESISER P.E. JOANNA PLUS ORGAN VOICING

A portable mains -operated Miniature Sound Synthesiser The basic live octave electronic piano P.E.( May/Sept 75 and CONSTANT DISPLAY FREQUENCY METER (PE AUG 78)
with keyboard circuits Although having slightly fewer A 5 -digit frequency counter for 1Hr to 99999Hz with a 1 Hz
facilities than the large P.E Synthesiser the functions Sound Design) has switchable alternative voicings for Honky- sampling rate. Readout does not count visibly or flicker due to
offered by this design give it great scope and versatility. Tonk, ordinary piano, and Harpsichord or a mixture of any of these display blanking.
Consists of 2 log VCOs. VCF. 2 envelope shapers. 2 voltage three, together with facilities including fast and slow tremolo,
controlled amps keyboard hold and control circuits. HE loud and soft pedal switching, and sustain pedal switching. The
Component set £2445
Printed circuit board £3431.
oscillator and detector. ring modulator. noise generator modification retains all the circuitry associated with the piano This kit & PCB are at 8% VAT (all others are 121961
mixer, power supply. but in addition provides an organ -voice envelope facility with 5
Set of basic component kits from £81.00 switchable pitches, variable attack and sustain, phasing and TAPE NOISE LIMITER
Set of printed circuit boards £849 vibrato.
Very effective circuit for reducing the hiss found in most tape
Set of components laird switches) for PSU, Frequency recordings. All kits include PCBs
generator, Pitch and Note Divider. Envelope Shapers, Voicings, Standard tolerance set of components £246
P.E. SYNTHESISER (P.E. Feb. 73 to Feb. 74) and Control circuitries. (Order as KIT 71-5) £99.25
The well acclaimed and highly versatile large-scale Superior tolerance set of components £3.78
Set of PCBs (Order as PCB SET 71-61 £29.113 Regulated power supply (will drive 2 sets) £4.89
mains -operated Sound Synthesiser complete with keyboard
circuits. Other circuits in our lists may be used with the
Synthesiser to good advantage.
SYNTHESISER TUNING INDICATOR (P.E. July 77) ENVELOPE SHAPER WITHOUT VCA (P E Oct. 75)
The Main Synthesiser: PSU. 2 linear VCOs. 2 ramp A simple 4 -octave frequency comparator for use with Provides full manual control over attack. decay. sustain arid
generators. 2 input amps. sample hold. noise generator. synthesisers and other instruments where the full versatility release functions. and is for use with an existing voltage
reverb amp. ring modulator, peak level circuit, envelope of the P.E. Tuning Fork is not required. controlled amplifier.
shaper, voltage controlled amp. Component set (incl PCB) £4.77
Component and PCB (but ekcl sw.) £745'
Set of basic component kits £7949
Set of printed circuit boards £13.20
ENVELOPE SHAPER WITH VCA (P.E. Apr 761
The Synthesiser Keyboard Circuits (can be used without the GUITAR FREQUENCY DOUBLER (P.E. Aug. 77) This unit has its own voltage controlled amplifier and has full
Main Synthesiser to make an independent musical instrument): A modified and extended version of the circuit published.
manual control over attack, decay. sustain and release
functions.
2 logarithmic VCOs. divider. 2 hold circuits, 2 modulation amps, Component set and PCB £442 Component set (Ind PCB)
mixer. 2 envelope shapers and PSU. £6.68
Set of basic component kits £4744
Set of printed circuit boards £748 TRANSIENT GENERATOR (P E Apr. 771
GUITAR SUSTAIN (P.E. Oct 77) An envelope shaper without VCA. having the usual attack
Maintains the natural attack whilst extending note duration. decay. sustain and release functions. and in addition it also
GUITAR EFFECTS PEDAL (P.E. July 75) Component set, PCB and foot switches £5.13 provides a Repeat Effect enabling a synthesiser to be
Modulates the attack. decay and filter characteristics of an Component set. PCB and panel switches £3.71 programmed to imitate such instruments as a mandolin or
audio signal not only from a guitar but from any audio banjo
source. producing 8 different switchable effects that can be Component set £4.87
further modified by manual controls. Possibly the most Printed circuit board £1.82
WIND AND RAIN UNIT
interesting of all the low-priced sound effects units in our A manually controlled unit for producing the above -named
range. Circuit does not duplicate effects from the Guitar sounds.
Overdrive Unit. WAVEFORM CONVERTER
Component set tir.cl PCB) £4.211
Component set with special foot operated switches £749 Slightly modified from a circuit published in "Elektor". Converts
Alternative component set with panel switches £545 a saw -tooth waveform into four different waveforms: sine -wave.
Printed circuit board £143 GUITAR OVERDRIVE UNIT IP E. Aug. 76) inark-space saw -tooth, regular triangle form, and squarewave
Sophisticated versatile Fuzz unit. including variable and with an externally variable mark -space ratio.
switchable controls affecting the fuzz quality whilst retaining Component set (incl. PCB but excl, sw/s)
the attack and decay. and also providing filtering. Does not £8.40
SOUND BENDER (P E. May 74) duplicate the effects from the Guitar Effects Pedal and can
A multi -purpose sound controller. the functions of which be used with it and with other electronic instruments.
include envelope shaper. tremolo, voice -operated fader. Component set using dual slider pot VOLTAGE CONTROLLED FILTER (P.E. Dec. 74)
automatic fader and frequency -doubler. E7.58
Component set using dual rotary pot £649 Part of the P E Minisonic now released as an independent
Component set for above functions (excl. SWsl £8.77 Printed circuit board kit for use with other synthesisers.
Printed circuit board £1.81 £1.62
Optional extra -additional Audio Modulator, the use of Component set lincl. PCB) (Order as Kit 65-1) £7.17
which. in conjunction with the above component set. can FUZZ UNIT
produce jungle -drum rhythms. Simple Fuzz unit based upon P.E. "Sound Design" circuit.
Component set (incl. PCB) Component set (incl. PCB) RING MODULATOR (P.E Jan. 75)
£2.88 £245 Part of the P.E.Minisonic now released as an independent
kit for use with other synthesisers.
PHASING UNIT (P.E. Sept. 73) TREMOLO UNIT Component set (incl. PCB) (Order as Kit 59-11
A simple but effective manually controlled Based upon P.E Sound Design- circuit. £5.50
unit for
introducing the phasing sound into live or recorded Component set (incl. PCB) £2.94
music
Component set (incl. PCB( NOISE GENERATOR (P.E. Jan. 75)
£3.20 Part of the P.E. Minisonic now released as an independent
TREBLE BOOST UNIT (P.E. Apr 76) kit for use with other synthesisers.
PHASING CONTROL UNIT (P E. Oct 74) Gives a much shriller quality to audio signals fed through it Component set (incl. PCB ) (Order as Kit 60-1) 63.64
For use with the above Phasing Unit to automatically control The depth of boost is manually adjustable.
the rate of phasing.
Component set ( mncl PCB) Component set (incl. PCB) £241
£4.74 SOPHISTICATED POWER SUPPLIES
A wide range of highly stabilised low noise power supply kits
SOPHISTICATED PHASING AND VIBRATO UNIT is available -details in our lists.
A slightly modified version of the circuit published in P.E. TUNING FORK (P.E. Nov 751
Elektor December 1976. and includes manual and Produces 84 switch -selected frequency -accurate tones. A
automatic control over the rate of phasing and vibrato LED monitor clearly displays all beat note adjustments. Ideal MICROPHONE PRE -AMP (P.E Apr 771
Component set £17.38 Component set (incl PCB) £3.82
Printed circuit board for tuning acoustic or electronic musical instruments.
£2.33 Main component set (incl. PCB) £14.93
WAH-WAH UNIT (P.E. Apr. 761 Power supply set (incl. PCB) £548 VOICE OPERATED FADER (P E Dec 731
The Wah-Wah effect produced by this unit can be controlled For automatically reducing music volume during
manually or by the integral automatic controller. talk -over -particularly useful for Disco work or for
Component set (incl PCB) £3.83 home -movie shows.
Component set (Inc! PCB) £3.97
AUTOWAH UNIT (P.E Mar 771 New Electronic Piano.
Automatically produces Wah-pedal and Swell -pedal sounds Elektor Aug. 1978
each time a new note is played DYNAMIC RANGE LIMITER (P E Apr 77)
Component set. PCB. special foot switches £7.67 Details in our list. Automatically controls sound output to within a preset
Component set and PCB. with panel switches level
f4-83
Component set (incl. PCB) £448
POST AND HANDLING
U.K. orders -under E15 add 25p plus VAT, over £15 add 50p EXPORT ORDERS are welcome. though we advise that
plus VAT. Keyboards £2.00 plus VAT. DON'T FORGET VAT!
a current copy of our list should be obtained before
Optional Insurance for compensation against loss or damage Add 12i% (or current rate if changed) to full ordering as it also shows Export postage rates. All
in post, add extra 50p for cover up to E50, £1.00 for f 100 cover,
£2.00 for £200 cover.
total of goods. post and handling. (Does not payments must be cash -with -order. in Sterling and
Eire, C.L. B.F.P.O., and other countries are subject to apply to export orders). preferably by International Money Order or through an
Export postage rates. English Bank. To obtain list send 50p.

PHONOSONICS DEPT. PE60 22 HIGH STREET SIDCUP KENT DA14 6EH FS'Agli-F1 YOrTRN OINCALLERS PLEASE

,1 Ni
Practical Electronics October 1978
 ENGINEERS

AND OTHER PROJECTS

PHOTOGRAPHS in this advertisement
show two of our units containing some of
the P.E protects built from our kits and tf:
PCBs The cases were built by ourselves
and are not for sale. though a small
selection of other cases is available

LIST-Send stamped addressed

YOURSELF FOR A
envelope with all U K requests for free
list giving fuller details of PCBs. kits and
other components
OVERSEAS enquiries for list Europe -
BETTER JOB WITH MORE PAY!
send 20p: other countries-send 50p. Do you want promotion, a This easy to follow GUIDE
better job, higher pay? "New TO SUCCESS should be read
KIMBER-ALLEN opportunities" shows you how by every ambitious engineer.
to get them through a low- Send for this helpful 44 -page
KEYBOARDS AND CONTACTS cost, Home Study Course. free book NOW! No obligation,
Kimber-Allen Keyboards as required for many published circuits. The manufacturers claim that
these are the finest moulded plastic keyboards available. All octaves are C to C, the keys are There are no books to buy nobody will call on you. It
plastic, spring -loaded, fitted with actuators, and mounted on a robust aluminium frame. and you can pay as you learn. could be the best thing you
3 Octave 137 notes) £25.50 ever did.
4 Octave (49 notes) £32.25
5 Octave 161 notes) £39.75
Contact Assemblies (gold -clad wire) for use with the above keyboards 11 required for each
note):
CHOOSE A BRAND NEW FUTURE HERE
Type GJ: Single -pole change -over each 250
Type GB:2 pairs of contacts, each pair normally open each 281p ,gamommil In CUT OUT THIS COUPON MI
Type GC: 3 pairs of contacts, each pair normally open each 37.1.p
Type GE: 4 pairs of contacts, each pair normally open each 46.I.p Tick or state subject of interest.
Type GH: 5 pairs of contacts, each pair normally open each 581p
Type 4PS: 3 pairs of contacts plus single -pole changeover each 57p Post to address below.
Printed Circuit Boards for use with GJ. GB and 4PS contacts (thus eliminating much interwir-
ing/ are available. Details in our lists. ELECTRICAL & Radio, Servicing & Painting &
ELECTRONICS Repairs Decorating
TRANSISTORS Practical Radio & Radio Amateur's
AC128 32p Electronics Exam. MECHANICAL
RHYTHM GENERATOR
15 -Rhythm Tempo, Timing and Logic control unit (excl. sw's 21,1 (with KIT)
f975
3p
128p A.M.S.E. (Mech.) E
but incl. PCBI BC108 13p Electronic AUTO & AERO
10 -Instrument Effects circuits f14.23 BC109 15p Engineering General Mech.
£4.25 BC109C 18p Motor Mechanics D Eng.
PCB for Effects circuits
£8.75 BC177 18p Certificate
Power Supply incl. PCB
BC184 llp General Elect. Eng. C. & G. Motor V. Inst. Engineers
BC187 18p Mechanics Technicians
128 -NOTE TUNE -PROGRAMMABLE SEQUENCER BC204 10p Certificate
BC209C 13p General Auto Maintenance
(P.E. Nov/Dec 77) BC213 11p C. & G. Elect. Engineering Engineering
Enables a voltage controlled synthesiser to automatically play BC214 llp Installations
pre-programmed tunes of up to 32 pitches and 128 notes long. BC262 18p A.M.I.M.I. Welding
Programs are keyboard initiated and note length and rhythmic BC415 15p Elect. Install. &
BC478 15p Work Air Registration
pattern are externally variable. (Please use order codes quoted in BD131 60pBD132 Board Certs.
brackets.) 44p C. & G. Elect. Dip.
MANAGEMENT &
Main Circuit (Nov) excl. sw's (KIT 76-11 £18.03 BF244A 32p
Power Supply (KIT 76-3)
Trigger Inverter and Alt. Output (KIT 76-21
£4.72
£1.15
BF245A
BSV95A22p
MD8001 210p
38p
Technicians

CONSTRUC-
PRODUCTION
Computer
Programming El
I
LED Counter (KIT 76-41
PCB (as published) for KITS 76-1 & 3 (PCB 76A)
PCB for KITS 76-2 & 4 (PCB 768)
£2.10
£2.81
£2.54
0071
0072
RPY58A
T IS3
20
30pp
62p
50 p
RADIO &
TELECOM-
MUNICATIONS
TIONAL
Heating, Ventilating
Inst. of Cost &
Managements
Accts.
I
P.E. STRING ENSEMBLE (PE Mar -July 78) ZTX4108 & Air Conditioning 1-1

ZTX301 Tirf Colour TV

The new keyboard string -instrument synthesiser. ZTX384 12p Servicing
13p
171 Architectural
Basic component sets: ZTX501 Draughtsmanship DRAUGHTS-
Power Supply (KIT 77-1) £8.77 2N2219 28p C. & G. Telecoms.
f14.68 2N2646 70p Technician's Cert.El & Design MANSHIP &
Tone Generator (KIT 77-21 28p DESIGN
Diode Gates (KIT 77-3/ E18.81 2N2905 L.I.O.B.
Chorus Generator (KIT 77-41 £19.08
2N2905A2N2906
% C. & G. Radio, General
Voicing System (KIT 77-51
..
24p TV & Electronics Carpentry & Draughtsmanship -
£7'38 2N2907 Joiner),
Printed Circuit Boards: 2N3054 88p Mech. Cert.
Double -sided PCB for Power Supply, Tone Generator & Diode 2N3055 76p Plumbing A.M.I.E.D.
2N3702 12p Radio & TV Technology
Gates with most of the Matrix wiring as printed tracking
2N3704 12p Engineering Electrical
(PC8 771/13) £18.40 2N3819 24p General Building Draughtsmanship
£2.65 Course 1-1 I.
PCB for Chorus Generator (PCB 77C1 2N3820 61p
PCB for Voicing System (PCB 77D) £2.62 2N3823E 39p
Fuller details of kits & PCBs are in our lists. 2N5459 45p

FORMANT SYNTHESISER (Elektor 1977/78) INTEGRATED CIRCUITS G.C.E.

. Very sophisticated music synthesiser for the advanced con -
structor who puts performance before price. Details in our lists.
301
318
8 -pin DIL
8 -pin OIL
320-15---
48
220
195
Noiir -58 '0' & 'A' Level Subjects
DISCOSTROBE (P.E. Nov. 76) 324 14 -pin DIL 87 -over 10,000 Group Passes!
3419 -15 -- - 87
4 -channel light -show controller giving a choice of sequential 70 8 -pin DIL 48
random, or full strobe mode of operation 723 105 87
Basic component set f 18 19 723 14 -pin DIL 51
Printed circuit board £3.45 726 TO5 1005
741 8 -pin DIL 24
BIOLOGICAL AMPLIFIER (P.E. JanJFeb. 73)
Multi-function circuits that. with the use of other external
748 8 -pin DIL
4007 14 -pin OIL
4011 14 -pin OIL
4024 14 -pin OIL
17
57
17
Aldermaston College
equipment, can serve as lie -detector. alphaphone. cardiophone 4069 14 -pin DIL Dept. TPE 23, Reading RG7 4PF
etc. 4136 14 -pin DIL 128
Pre -Amp Module Components set (incl. PCB( £3.95 AM2833 8 -pin DIL 380
Basic Output Circuits-combined component set AY10212 16 -pin DIL617 also at our London Advisory Office, 4 Fore Street Avenue, London
with PCBs, for alphaphone, cardiophone, frequency AY16721/6 188 EC2Y 9DT. Tel. 628 2721.
meter and visual feed -back lampdriver circuits. £6.59 CA3046 14 -pin OIL 71
Audio Amplifier Module Type PC7
. CA3080 8 -pin DIL 83
£7.7' CA3084 14 -pin DI1209 NAME (Block Capitals)
FX209 16 -pin DIL729
LM323 --- 562
M252 16 -pin DIL680 ADDRESS
10% DISCOUNT VOUCHER (PE88) MC3340 8 -pin DIL 150
MCM6810 24 -pin DIL670
TERMS: Correctly cowed, C.W.O., U.K. orders over £50 SG3402N 14 -pin DIL 595
goods value. Valid until end of month on cover of P.E. This STK025 --- 595 Postcode
voucher must accompany order. TDA1022 16 -pin DIL582
XR2207 14 -pin DIL420 Age
ZN425E 16 -pin DIL375 Other subjects of interest
Accredited by C.A.C.C. Member of A.B.C.C.
PRICES ARE CORRECT AT TIME OF PRESS.
E. a 0. E. DELIVERY SUBJECT TO AVAILABILITY. PHONOSONICS HOME OF BRITISH INSTITUTE OF ENGINEERING TECHNOLOGY

I W'
Practical Electronics October 1978
 *)ic; WIRE WRAPPING CENTRE
HOBBY WRAP
Model BW 630 WIRE -WRAPPING TOOL OK PLIERS AND
For .025" (0,63mm) sq. CUTTERS
Post "MODIFIED" wrap. 3 IN 1 WIRE DISPENSER
Positive indexing. anti. New wire dispenser cuts UNIVERSAL CUTTER
overwrapping device. and strips three different Cuts everything. Leather,
Battery colours of wire. Quick and wire, plastic, tin-plate,
For AWG 30 BW-630 Cardboard. Stainless steel
Wire - easy to use pocket size. blades.
wrapping For AWG 26.28 BW-2628 £3.77 Just one of the range of
Tool high quality pliers, cutters.
Complete tweezers and screwdrivers.
with Bit Bit for AWG
and SI 26.28 131.2628
Line A 477 IC TEST CLIPS£277
WIRE -WRAPPING KIT
DIP/IC EXTRACTOR Contains: Hobby Wrap
DIP/IC INSERTION Tool WSU-30 M, Wire FOR DUAL -IN -LINE
TOOL £1.18 TOOL WITH PIN Dispenser WD -30-13,!2) PACKAGES
The EX -1 Extractor is STRAIGHTENER 14 MP's, (2) 16 DIP s, Provide full access to
ideally suited for bobby Hobby Board H -PCB -1, Integrated circuit DIP
enthusiast or lab engineer. DIP/IC Insertion Tool leads.
Featuring one Piece Wring INS -1416 and DIP/IC Solve probe attachment Remove DIP's damage
steel construction. It will £2,58 Extractor Tool EX -1. problems free,
extract all LSI, MSI and WIre-Wrapping WK -48 Simplify prototype and
551 devices of from 8 to Kit Available In sizes to
24 pins. (Blue) production testing, field accommodate all DIP's;
Extractor Tool E X1. INS -1416 service work, and quality TC-14 fits 14 -pin DIP's
£17.82 control. etc.

DIP SOCKET
Dual -In -fine package, 3
level wire -wrapping,
phosphor bronze contact,
gold plated pins . 025
03.63mrn) sq., .100
(2,54mm) ten re spacing.
14 Pin Dip
FROM Socket
14p 16 Pin Dip
FROM 75p Socket
TERMINAL AND Are offered In ten
DISTRIBUTION STRIPS configurations. 1,, '

Bread boarding building Accept all components HOBBY WRAP TOOL RIBBON CABLE ASSEMBLY £2.40
blocks with universal with leads up to .032" With 14 Pin Dip Plug 2 Long
matrices of solderless diameter. Wire -wrapping, stripping,
olug-in tiePOInts. Require no special patch unwrapping tool for With 14 Pin Dip Plug -4" Long
AWG 30 on .025 (0,63mrn) Regular
Facilitate quick, Cords. Square Post. Wrap A WSL630
solderless circuit build-up Includes integral non - with 16 Pin Dip Plug 2' Long.
and check-out on shorting instant mounting A£4.39 6E4.69 Modified. With 16 Pin Dip Plug -4' Long
universal .1" ft .1" matrix. backing. Wrap WSLI-30M With (6 Pin Dip Plug -8 Long

DISTRIBUTORS OK Machine&Tool U.K. DISTRIBUTORS

WANTED** * Limited
48a The Avenue Southampton SO1 2SY
Telephone Southampton(0703)38966 7 Telex477222 Cablegram OKNIAC
WANTED* **

NEW PRODUCTS NEW PRODUCTS

Wilmslow POWER AMP KIT
The kit includes all metalwork, heatsinks and hardware to house any two of our power amp
modules plus a power supply. It is contemporarily styled and its quality is consistent with that

Audio of our other products. Comprehensive instructions and full back-up service enables a novice io
build it with confidence in a few hours.

ADVANCED PRE -AMP CPR1

THE firm for speakers! This stereo module accomplishes pre -amplification of disc and other inputs to an impeccable
standard. The disc input has no common mode distortion effects, thd of .001%, 40dB overload.
70c18 s/n. and 6V1p5 slew rate. Other inputs have 70mv sensitivity. thd of .001%. 90d13 s/n.
12dB/octave subsonic filter. 4V/pS slew rate and active balance control. Output is delayed for
10 seconds. No controls are fitted.
SEND 15p STAMP FOR THE WORLD'S BEST CATALOGUE OF
SPEAKERS, DRIVE UNITS, KITS, CROSSOVERS, ETC. AND
DISCOUNT PRICE LIST MOVING COIL PRE -AMP MC1
This stereo module uses multiple input transistors to achieve 65dB s/n. Sensitivity is switched
70 or 160pV for 3.5mV output.

ACT AUDAX BAKER POWER SUPPLY

BOWERS & WILKINS 0 CASTLE CELESTION The regulator module, REG 1 provides 15-0-15v to power the CRP 1 and MC 1. It can be used
with any of our power amp supplies or our small transformer TR 6. The power amp kit wifl
CHARTWELL COLES DALESFORD accommodate a REG 1.

DECCA EMI EAGLE ELAC FANE POWER AMPLIFIER MODULES POWER AMP KIT £32.40
GAUSS GOODMANS HELME I.M.F. CE 608 60W/8 ohms 35-0-35v £16.30 PRE -AMPS:
CE 1004 100W/4 ohms 35-0-35v £19.22 These am available in two versions
ISOPHON JR JORDON WATTS CE 1008100W/8 ohms 45-0-45v
,,,,-.
£23.22 uses standard components, and the othe.
CE 1704 170W/4 ohms 45-0-45v f29.12 (the Si uses MO resistors where necessary
KEF LEAK LOWTHER McKENZIE CE 1708 170W/8 ohms 60-0-60v £31.90 and tantalum capacitors.
CPR1 £29.49 CPR1S E39.98
MONITOR AUDIO PEERLESS RADFORD TOROIDAL POWER SUPPLIES MC1 £18.50 MC1S (2949
CPS1 fort xCE 608 or 1 xCE 1004 £14.47 POWER SUPPLY:
RAM RICHARD ALLAN SEAS CPS2 for 2 x CE 1004 or 2/4x CE 608 £16.82 REG 1 £6.75 TR6 £1.75
CPS3 for 2 xCE 1008 or 1 xCE 1704 E17.66 BRIDGE DRIVER, 11D1
TANNOY VIDEOTONE WHARFEDALE CPS4 for 1 xCE 1008 £15.31 Obtain up to 340W using 2 x 170W amps
CPS5 for 1 xCE 1708 £22.68 and this module.
CPS6 for 2 xCE 1704 or 2 x CE 1708 £23.98 801 £6.40
HEATSINKS
WILMSLOW AUDIO (Dept. P.E. 8) Light duty. 50mm, 2°C/W
Medium power, 100mm. 1.4°CNV
Disco/group. 150mm.
£1.30
£2,20
£2.85 CRIMSON
SWAN WORKS, BANK SQUARE, WILMSLOW, Fan, 80mm, state 120 or 240v f18.50
Fan mounted on two drilled 100mm heatsinks. ELEKTRIK
2 x.4.CAN, 65°C max with two
CHESHIRE SK9 1HF 170W modules £29.16 1A STAMFORD STREET
LEICESTER LE1 6NL
THERMAL CUT-OUT, 70°C £1.90
Discount HI-FI, etc. at 5 Swan Street and 10 Swan Street Tel. (0533) 537722
Tel. Wilmslow 29599 for Speakers Tel. Wilmslow 26213 for Hi-Fi All prices shown are UK only and include VAT and post. COD 90p extra, E100 limit. Export is no
problem, please write for specific quote. Send large SAE or 3 International Reply Coupons for
detailed information.

Practical Electronics October 1978

Ina VOLUME 14 No. 14 OCTOBER 1978

SMUG VALUE we can all benefit from in one way or

E ALL like to feel a bit smug some With the inclusion of more editorial another.
W times and we hope P.E. has a
right to this month-though not for
pages per issue in recent copies of
P.E.-and such items as the free
If readers have devised other cost
saving circuitry we would be pleased to
long! The V.D.U. System construction STICKIES, 8 -page supplement next hear from them. Even if you have an
project which appears in this issue is month and some planned special offers idea for some equipment a letter to us
believed to be the first design etc., we have been doing our best to could set a few minds going and
published in Britain, and makes use of give good value for money and will, of maybe a designer working?
an excellent Thomson CSF chip which course, continue in this way. However, To give an idea, a spontaneous
has recently become available on the as we said above, we won't be staying invitation for suggestions from the
amateur market. The new chip smug for too long as next month the office brought forth the following:
incorporates most of the electronics price of P.E. will rise to 50p. An independent timing device to
required to produce a memory mapped The last price increase was with the display the cost of a telephone call
system. November 1977 issue-exactly a year (local or distant), and along similar
The unit provides, at a relatively low ago and, as we all know, inflation has lines, a meter for mains power
price, one of the most useful and no doubt will, continue. Our costs consumption reading pence per hour.
peripherals for the home computer go up and reluctantly these must
man. All components, including the eventually be passed on. We hope you PARTICIPATION
modulator, are on one "small" p.c.b. will still consider P.E. good value for We try to keep Readout interesting
which includes 1K of user RAM money. each month and publish the "bad" with
mounted in a novel way. the "good" and sometimes even the
The second item which we feel is SAVING "ugly"-see page 1102-but so much
worthwhile is the sheet of STICKIES, Over the years we have presented a depends on you transmitting your
free with this issue. We have said they number of projects to help readers to views and thoughts! It is good to see
are worth 60p, which is true, but in fact save money in one way or another and some interesting and constructive
with postage etc. you would have to our Fuel Consumption Meter in this submissions to Microbus this month
spend 80p to get this product. Since issue is no exception. The price of oil and, as always we have plenty of I.U.'s,
they are so useful (see page 1093) we regularly makes the headlines and no but please don't forget that Readout is
are sure most readers will consider doubt it will not be long before this your page so keep the letters coming
them a very worthwhile gift. They are, happens again. With the aid of our and we will keep publishing the
of course, worth more than the cost of consumption meter better fuel interesting and informative ones.
the issue! economy can be achieved-something Mike Kenward

Editorial Offices:
EDITOR Westover House,
West Quay Road, Poole,
Mike Kenward Jack Pountney ART EDITOR Dorset B H15 1JG
Keith Woodruff Phone: Editorial Poole 7 1
Gordon Godbold ASSISTANT EDITOR SENIOR ARTIST 191

We regret that lengthy technical

Mike Abbott TECHNICAL EDITOR John Pickering SEN. TECH. ILLUSTRATOR enquiries cannot be answered
over the telephone.
Alan Turpin PRODUCTION EDITOR Isabelle Greenaway TECH. ILLUSTRATOR
Advertising Offices:
David Shortland TECH. SUB EDITOR Judith Kerley SECRETARY King's Reach Tower,
King's Reach, Stamford Street, SE1 9LS
Phone: Advertisements 01-261 5000
Telex: 915748 MAGDIV-G

ADVERTISEMENT P. J. Mew REPRESENTATIVE Make Up and Copy Dept.

MANAGER D. W. B. Tilleard C. R. Brown CLASSIFIED MANAGER Phone: 01-261 6601

Subscriptions Magazines Ltd., Lavington House, 25 made payable to IPC Magazines Limited.
Copies of PE are available by post, inland or Lavington Street, London SE1 OPF, at 65p
overseas, for £1060 per 12 issues, from: each including Inland/Overseas p & p. Letters
Practical Electronics, Subscription Depart- Binders for PE are available from the Queries regarding articles published in PE
ment, Oakfield House, Perrymount Road, same address at £2.85 each to UK should be addressed to the Editor, at the
Haywards Heath, West Sussex R H16 3DH. addresses, £3.45 overseas, including Editorial Offices, and a stamped, addressed
postage and packing, and VAT where ap- envelope enclosed. We cannot undertake to
Back Numbers and Binders propriate. Orders should state the year and answer questions regarding other items,
Copies of most of our recent issues are volume required. nor to answer technical queries over the
available from: Post Safes Department, IPC Cheques and postal orders should be telephone.

1049
Practical Electronics October I 97R
 3 -RAIL POWER SUPPLY
A three -rail Eurocard power supply
announced by Lascar Electronics is suitable
for most circuits where digital and linear
devices are mixed.
The supply features one output of 5V IA,
and dual tracking outputs adjustable between

Market
±5V and 15V with a maximum of 100mA per

Place
Items mentioned are usually available from electronic
equipment and component retailers. However, where
a full address is given, general enquiries may
be made direct to the firm concerned.
All quoted prices are correct at
time of going to press. rail. The 5V and twin -rail supplies are isolated
from each other and feature short-circuit,
by and over -temperature and fold -back over -current
Alan David protection. Input voltages 220V a.c. or 240V
a.c. The supply is fitted with terminal blocks
Turpin Shortland on the input and outputs, and is assembled on
a p.c.b. measuring 160 x 100mm, with a
WONDERBOARDS COMPACT TEMP CONTROLLER maximum height of 47mm.
Fresh in from across the big pond, Wonder - Capable of switching or controlling 3kW For details contact Lascar Electronics
board is a solderless breadboard system using directly, the CAL 6103 high power, compact Limited, PO Box 12, Module House,
holes filled with a conductive elastomer temperature controller is a panel mounted unit Billericay, Essex.
(rubber) as the connecting points. The contact with a DIN standard 48mm2 bezel, and a
points are accessible from both sides of the +I per cent accuracy (typical) under steady
board enabling components to be mounted load conditions. EXTRACTOR TOOL
one side and wire linking to be made on the The CAL 6103 is available to order in tem- Designed for the specific task of
other. Hole pitch is 0.1in and there are six perature ranges from 0°C to 1,600°C. Any automatically extracting i.c.s from p.c.b.s on
rows of 31 holes allowing up to a dozen 14 specified thermocouple input, or PT100, can completion of the desoldering operation, the
d.i.l. devices to be mounted. Each contact be supplied. DIP -OUT tool from Vero Electronics
point will hold up to six wires. Its proportional control system avoids the eliminates the danger of damage to i.c. legs by
virtue of its "even pull" action. When used
with a desoldering block it provides a fast and
efficient method of removing i.c.s. The price of
the tool is £5.67 plus VAT.

Specifications given are as follows:- unnecessary "hunting" encountered in other

contact resistance 10mi1, current capacity compact on/off temperature controllers. Time
7A, breakdown voltage 9kV, insulation cycling is set to a "standard" 20 secs which
resistance 10,000MC1, min/max wire suits most applications. However, CAL will
diameters 0.2 to 0.8mm (32 to 20 gauge), supply units with cycle times from 5 secs to
contact life 150 insertions, useful temperature 120 secs to order.
range -55 to +100°C. No noise/frequency For resistive loads the output/control relay
figures were given but have been requested. will switch 14A at a.c. mains voltages. A static
Wonderboards are available singly at £2.50 output can also be provided to accommodate
from Charcroft Electronics, and distributor remote thyristor control systems.
enquiries are invited. For further information contact Controls & For further information contact Vero Elec-
Charcroft Electronics, Charcroft House, Automation Limited, Regal House, 55 Ban- tronics Limited, Industrial Estate, Chandler's
Sturmer (Haverhill), Suffolk. Tel. 0440 5700. croft, Hitchin, Herts. Ford, Eastleigh, Hampshire.

1050 Practical Electronics October 1978

MICRO -BOARD
With the increasing use of S100 boards and
bussing systems in microcomputers, Vero
Electronics have released a universal S100
bus -compatible prototyping board. Designed
for the manufacture or breadboarding of
microprocessor, memory or interface assem-
blies the board will, without modification,
mount directly into any equipment using the
S100 bus system.

PROGRAMMABLE TV GAMES plus interface circuitry, and all sets will feature
The board has an S100 edge connector General Instrument Microelectronics have realistic sound generation and on -screen scor-
configuration (100 gold-plated contact fingers introduced a new set of MOS microcircuits for ing.
on 3.175mm/0.125in pitch) and is fully use in cartridge -based programmable TV Some of the cartridge -mounted microcir-
pierced with 1.02mm/0.040in diameter holes games. Known as SYSTEM 8601, the circuits cuits are already available, including the 8610
on a 2.54mm/0.1in matrix. Provision is made
include a clock generator, colour encoder, "Supersport" (20 games), the 8765 "Motorcy-
for mounting up to four standard TO -220 modulator and a selection of cartridge cle" (8 games) and the 8603 "Road Race" set
plastic package regulators together with heat - microcircuits-enabling fully programmable (3 games). Three more circuits-the 8607
sinks for on board regulation, and the voltage games systems to be built at low cost. "Target" (12 games), the 8606 "Wipeout" (24
plane is capable of being divided to provide up Each games system will consist of a console games) and 8605 "Warfare" (10 games)-will
to four separate positive or negative supply into which individual game set cartridges are go into production within two months, with
rails. The component side of the board carries
slotted. Each console will contain clock, en- more to follow before the end of the year. For
a ground plane which can be used for termina-
coder and modulator, as well as game con- further information contact General Instru-
tions or screening and the wiring side carries trols, switches, power supplies, etc. Each car- ment Microelectronics, Regency House, 1-4
both voltage and ground planes, thus tridge contains individual games microcircuits, Warwick Street, London, W IR 5WB.
providing for up to five planes.
A wide range of compatible standard
accessories such as DIP sockets, pins,
headers, ribbon cables, etc. is available, CRUSH PROOF DMM +0.02 per cent of reading +0.01 per cent of
enabling ihe prototyping board to cope with A new series of true r.m.s. 4} -digit full scale for a full 6 months. Care was taken
virtually any microprocessor or multimeters for bench and field use has been in designing the circuit to choose components
microcomputer circuit requirement. introduced by Systron-Donner Limited. that minimised drift.
For further information contact Vero This new series consists of four models, Two extra cost options can be specified:
Electronics Limited, Industrial Estate, available with a choice of d.c. accuracies of one adds an analogue meter to the front panel.
Chandler's Ford, Eastleigh, Hampshire. either 0.02 per cent or 0.05 per cent, and with This gives the user the ability to make nulling
a choice of current or dB measuring modes. and/or peaking measurements and the other is
All models feature auto and manual range a battery pack. An internally mounted set of
selection with a.c. and d.c. voltages from 10
microvolts to 750V and 1,000V respectively,
measured in five ranges. A true r.m.s. a.c.
converter permits accurate measurements of
triangles, pulses, square waves or distorted
sinewaves up to 20kHz.
The resistance mode offers six ranges
allowing measurements from 0.010 to 20Ma
All ohms ranges are protected against input
overloads of up to 350V r.m.s.
This multimeter will also measure dBs from
-60 to +60 in five manual ranges. This
capability is especially useful in checking long
line voice communications. The dB mode is six nicad batteries provides approx. 2+ hours
offered in place of the 5 d.c. and a.c. manual of continuous operation between charges.
£100 SCOPE current modes which cover measurements Portable DMMs need to be packaged to
The Elmac 4810 single beam oscilloscope from 1 microamp to 2 amps. withstand frequent handling and accidental
will interest many constructors because of its The cost of a DMM is directly related to drops. To prevent damage, the unit is installed
low cost (£99.00 plus VAT) and excellent the d.c. accuracy specification. Since in a clamshell -shaped case made from
specification which includes 4in CRT, d.c. to applications can vary, Systron-Donner Cycloy-the new ABS/Polycarbonate plastic
5MHz bandwidth (vertical axis), am input decided to offer its new Portable DMM with alloy. The result is a case which is drop -proof
impedance and a maximum input voltage of two different basic d.c. accuracies. The Model and crush -proof.
600V peak to peak. 7141A, which is the lowest priced has a d.c. For further information including price
For further information contact Gemini accuracy of +0.05 per cent of reading +0.05 contact Systron-Donner Limited, St Mary's
Electronics, Newton Building, Newton Street, per cent of full-scale for a full 6 months. The Road, Sydenham Industrial Estate,
Manchester 1. Model 7141B offers a basic d.c. accuracy of Leamington Spa, Warwickshire.

October 1978 1051

Practical Electronics
 4 -DIGIT PRESET COUNTER
A new 4 -digit counter module claimed to be
capable of almost all counting functions has
been recently introduced by Lascar
Electronics. Working from a +5V d.c. supply,
the module incorporates 0.43in high efficiency
I.e.d.s and is capable of counting at rates up to
2MHz. Besides normal counting from input
pulses, the display can be set from external
BCD sources.
The module also incorporates an internal
register. When counter and register are level,

VIDEO SYSTEM Three, two and one hour tapes are available
The consumer's choice in video recorders is at £13.50, £10.50 and £8.00 respectively and
further extended this month with the arrival of these tapes can run on any of the other VHS
National Panasonic's VHS (video home recorders on the market in this country.
system) NV8600. Lining up with National Panasonic to offer
an "equals" output is produced giving many The unit, which is similar in operation to an video home systems are Akai, Hitachi, JVC,
applications in batch counting, machine audio cassette deck with controls for play, Mitsubishi, Sharp and Thorn.
control etc. Thumbwheel switches can be used stop, rewind and fast forward also has a
to set levels in both cases.
The NV8600 which is priced at £750
TTL/CMOS compatible, the module also
remote "pause" control to enable easy editing including VAT is available through High
of unwanted material from a programme. Street TV retailers.
features carry -borrow and zero outputs and
count inhibit and store controls.
The count input has a Schmitt trigger ing bit feeding an operational amplifier which APPLE. An 8K ROM resident monitor
making the module suitable for use in noisy is switched via a zero crossing integrated cir- programme provides all peripheral control and
environments. cuit. This design avoids the need for moving user programming functions. Spare sockets
For details contact Lascar Electronics parts which may wear and eliminates voltage are included to further expand on -board
Limited, PO Box 12, Module House, transients in "Spiking", RF interference and program memory via user PROM -based
Billericay, Essex. the generation of magnetic fields. Proportional programs or Rockwell's assembler, text editor
control also ensures a precise temperature to and BASIC interpreter plug-in ROM options.
within ±2 per cent of the indicated dial
IRON CONTROLLER temperature-the dial may be locked onto
Miniaturisation of components and any specific temperature within the range of
increasingly complex printed circuit board 120-380°C.
design have brought in their turn the need for The unit is earthed from the supply to the
precise operator control of soldering irons. soldering bit to provide maximum safety
Apart from the likelihood of expensive against leakage currents, making the tool
damage caused by poorly earthed soldering suitable for use with the majority of voltage
instruments the operator now has to position sensitive components including FETs and
the soldering bit more carefully, often in close CMOS.
proximity to heat or voltage sensitive compo- For further details and a full specification
nents. on the unit contact Adcola Products Ltd,
Adcola House, Gauden Road, London
SW4 6LH.

ROCKWELL'S AIM
Rockwell, who recently announced a single
chip microcomputer called the R6500/l, have The AIM 65 board also has a connector
just introduced a single board microcomputer that allows external access to the system bur
system which features an on -board 20 column for memory and I/O expansion. A separate
printer and display with a full alphanumeric application connector interfaces a teletype and
keyboard. two standard cassette recorders, and includes
Designated the AIM 65 the system is inten- a user -dedicated Versatile Interface Adaptor.
ded as an educational aid for first time users The VIA features three 8 -bit bidirectional
and a general purpose microcomputer for ports (two parallel, one serial) and two 16 -bit
engineers. interval timer/event counters, thus allowing
To provide maximum operator control, The AIM 65 is available in I K and 4K byte the user to interface his own system, in many
Adcola Products Ltd has designed a new Unit RAM versions, is designed around the 6502 cases without the need for extra interface
101 TS model which features a far shorter and CPU which has 64K address capability with devices.
lighter soldering instrument. 13 addressing modes and is the The system which is priced at under £250 is
The main circuit design is based on a ther- microprocessor at the heart of other popu- stocked by Pelco (Electronics) Ltd., Enterprise
mocouple positioned at the rear of the solder - lar systems such as KIM 1, PET and House, 83/85 Western Road, Hove, Sussex.

1052 Practical Electronics October 1978

 name. The discoverer was James Christy from that the motion of Neptune was consistent
the Naval Observatory, Washington, DC. It with a body of 2 to 5 Earth masses at a dis-
was part of a study to refine the data tance of between 50 and 100 astronomical
regarding Pluto's orbit which is a nominal 248 units. The suggested longitude would be be-
years. The plates examined showed an elonga- tween 310° and 350°. At the same time they
tion of the planet. made it quite clear that they did not think that
This set Christy the task of confirmation there was such a planet. The reason for this
from other photographs that had been taken. was that at the time of the search for Pluto the
He made an examination of the photographs Lowell Observatory covered so much of the
taken from the same observatory in 1970 and sky in their search that if there had been a
in 1965. The telescope used was that situated body of reasonable brightness it would not
in Arizona (Flagstaff). These pictures had the have been overlooked. However a spherical
same evidence but the observers then had coverage was not made.
decided elongation was due to a plate fault. Here is the point where present space ac-
A confirming plate was taken with a 4m tivity meets with astronomy and this recent
telescope at Cerro Tololo Inter -American Ob- discovery. August SPACEWATCH gave
servatory in Chile. Also a third confirmation details of the mission for the exploring of the
has come from J. Derral Mulholland from areas around the Sun out of the plain of the
photographs taken in 1977 at Macdonald Ob- ecliptic. This could very well reveal such a
servatory in Texas. However as there has not body or indeed the two bodies suggested by
been a plate so far that shows a division be- the Russian astronomers.
tween the planet and the satellite, final confir- The classical theory of Pluto's origin is that
mation cannot be assumed. it was once a satellite of Neptune. It was
While resolution has not been attained the thought that it orbited Neptune every 6.4 days
fact is that if it is not a satellite then it will but came to near collision with Triton, another
have to be concluded that Pluto is several Neptunion satellite. The result of this encoun-
times longer than it is wide. In other words ter threw Triton into its present retrograde and
FRANK W. HYDE more like one of Mars' satellites. This would ejected Pluto to become a planet of the Sun.
seem highly unlikely. The very existence of a There is another matter to be considered
satellite immediately provides atronomers with and that is whether in fact Pluto and its
PLUTO a tool to measure the parent body. satellite is a binary unit. With the present
Once again doubts about the most distant Robert Harrington, of the Naval Obser- figures it would suggest that the two bodies
planet yet to be discovered in the solar system vatory, has given the centre to centre distance revolve about a centre 6800km from the cen-
arise. It is a reminder that each new set of data between the planet and the satellite as tre of Pluto. Thus there would be a system
which becomes available can seriously upset 17,000km. Its diameter is set at about 40 per which behaved in the manner of a body
previous ideas. There have been many ex- cent of Pluto. If this is so, then the satellite is 13,600km in diameter. This aspect well
pressed doubts about Pluto, more perhaps the largest, in proportion to its parent, such deserves some consideration.
than in regard to the other bodies revolving body in the solar system. The orbital period is A mission to investigate seems a must.
round the Sun. 6.4 days. This means that it is stationary over Could it be that the Halley comet probe might
Only a short while ago the size of Pluto was one point on Pluto's surface, as Pluto's own do this after the cometary encounter. There
re -assessed. It demoted the planet from an es- period of rotation is calculated at 6.4 days. seems to be a good case for knowing once and
timated size of near to that of the Earth and of The estimate of density of the satellite in- for all whether Pluto does have a significance
the same density, to the size of the Moon. dicates that Pluto has a density of 0.002 of in the Solar system.
Quite plausible reasons were given for this. Earth.
The density was suggested to be about 01 of This alters entirely the current picture of the MORE FROM THE USSR
that of the Earth. Planet. Now it confirms the model that Pluto The success of the Soyus-30 and the
The acceptance of this meant that in no (because its density is less than that of water)
Progress -2 mission is already established. The
way could the perturbations of Uranus be may well be nothing but a snowball. That is a space -walk also marks another satisfactory
linked with the effects of Pluto and its prox- snowball of frozen gases. The infra -red obser-
point in the progress of Soviet ventures.
imity. As previously reported in vations from Kitt Peak, showed that a plen- The new furnace known as Kristall has
SPACEWATCH about three years ago the tiful covering of the gas methane (frozen) was been in use to produce pure monocrystals by
Soviet Union had calculated that there were apparent on the surface. the zone -melting technique. The furnace was
possibly two planets beyond Pluto. Brian Marsden of the Smithsonian used to form a monocrystal of gallium ar-
The two planets were shown to respond to a Astrophysical Observatory who is responsible senide from a high temperature solution. The
position from the Sun, but no celestial coor- for the coordination of new discoveries has new furnace is installed in the transfer tunnel
dinates were offered. The suggested distances said that perhaps Pluto should be re-classified
of Salyut -6. The crew have also been working
were: one at a distance of 54 astronomical as a minor Planet.
on the Splay furnace to obtain new semi-
units from the Sun which would imply a possi- Theories have been offered by Robert
conductor materials and compounds of
ble diameter of 12,000 miles; the second was Harrington and T. Van Flandern of the Naval aluminium and tin and molybdenum.
set at 100 astronomical units from the Sun Observatory. The foremost hypothesis is that
with a diameter of 18,000 miles. In that event an unknown planet at some time in the past
the period of the first one could be of the order passed through the satellite system of Nep-
COPERNICUS DISCOVERS
of 350-370 years and that of the second of the tune. If it had a mass of four times that of the BLACK HOLE
order of 1,000 years. It must be remembered Earth it would have disrupted the system and Among the instruments on the Orbiting
that the whole of these data represent a com- Pluto ejected as a result. The new satellite of Astronomical Observatory known as Coper-
puter mode. No visual identification has been Pluto could have been created then. If this nicus there is an X-ray telescope from Univer-
made. were the case then the intruding body would sity College, London. It is this instrument
Now a new situation arises as the result of have been violently thrown about and could which observed the X-rays of the super -giant
the discovery of a satellite associated with now be a tenth planet at a distance of 50 to double star in the constellation of Scorpio.
Pluto. This body has been named Charon, the 100 astronomical units from the Sun. It would Work which began in the 70's under Norman
name bestowed upon it by its discoverer. The be too faint to be easily seen and a long Walker of the Royal Greenwich observatory
present official designation is 1978-P 1. Until programme of searching might be necessary had shown that the super -giant had an unseen
the details are truly confirmed retains the to locate it. companion. The star is about 5,000 light years
number. However there seems to be little This agrees with a previous study in 1972 from Earth. The amount of X-rays received
doubt that it is a satellite and in accordance when Rawlins and Hammerton were indicate that the unseen object must be a
with custom the discoverer has the choice of searching for another planet. They suggested collapsed star.

1053
Practical Electronics October 1978
 PRACTICAL ELECTRONICS
VV VU DDIEDD UU UU

UV UU 0000000 UU UU

UU VU OD no UU UU

UU UU OD DD UU UU

MAN DDIEDDD UUUUUUUUU

UVU 000000 UUUUUU

SYSTEM Part 1 T.BERK

LATEST DEVICE = LOWEST PRICE = SIMPLEST CONSTRUCTION = MEMORY MAPPED VDU

THIS project has been written to satisfy one of the most The design is based around the new chip by Thomson-
I important needs of the home microcomputer CSF which carefully controls the display timing with a
constructor-an inexpensive output device for ASCII minimum of extra chips. This i.c. also generates a flashing
characters. The VDU shown here uses the very latest "one cursor with full position control, and allows the screen to be
chip" VDU controller and provides, among other things: scrolled in the fashion of a roll of teletype paper in action (all
(a) 16 lines x 64 ASCII characters. hardware functions within the chip). This is described in
(b) Full memory mapping, enabling random access to any detail later.
part of the screen. The VDU has ten address, eight data and seven control
(c) An extra 1K bytes of user RAM. lines which interface to the standard bus systems of most
(d) Full cursor control and screen scrolling in hardware. MPU designs. The timing of the unit is generated using a
(e) High speed (limited only by MPU). 1 MHz quartz crystal.
(f) An inexpensive and easily constructed design. All character information is in standard ASCII character
(g) An excellent addition to an evaluation kit. coding. It is advisable to keep, close at hand, a copy of the
hexadecimal equivalents to each of the 64 characters in the
The output from the unit is either in the form of video 2513 character generator.
information suitable for a video monitor (or modified TV), or
To interface a VDU to a computer system, some basic
UHF modulated information to plug straight into a TV aerial
software is required. The VDU programme which suits your
socket.
machine will depend upon its resident monitor. The basic
The VDU shown in Fig. 1 is a complete output peripheral
elements, however, of a VDU programme will be common to
for a computer of any type. The details described below are
most MPU systems. A general example is presented later to
orientated towards microcomputer based machines of 8 bit
help with VDU utilisation.
(one byte) word length, but apply almost unaltered to any
type of system. The machine contains a 1 kilobyte block of
user random access memory (RAM) which forms an addition
to the MPU's addressable memory. The VDU should be OPERATION
thought of as a "window" to this area of RAM where each The heart of the system is the Cathode Ray Tube
character position is a memory location in the micro- Controller (CRTC). The clock requirements of this chip are
computer. supplied by a TTL oscillator circuit which is then divided by
This type of VDU design has several advantages over the eight and fed to the clock input of the CRTC. To understand
straightforward video writer system which acts very much the working of this device, it is necessary to appreciate that
like a teletype, all information being sent sequentially, thus the brightness of a TV line is proportional to the voltage level
preventing the random selection of any character slot. applied to its video input.

1054 Practical Electronics October 1978

 MPU
DATA ENABLE
BUS
VDU SELECT

CO 7

BUFFER
RIW
DO b7
b0 b7

b0

DO D7

DATA OUT R/
D7

MPU
D/11/,,,TA
1k RAM ADDRESS BUFFER ADDRESS
IN BUS

D D5

LATCH LOAD
-Vl-
BUFFER

-101- 1MHz
b0 b5

RO
2513
CHARACTER R1 ADDRESS
GENERATOR
-.R2
CE
CRTC ST
PT
CO
b' }CURSOR
C1
CONTROL
LOAD
PISO SYNC C2
01
CLOCK

15 ENABLE

CTR OSC

VIDEO
GEN

TO AERIAL SOCKET
UHF OF DOMESTIC
MODULATOR TELEVISION SET
IDEO
OUT

Fig. 1. Block diagram of VDU. Connection of the data bus, address bus, and some common control lines will allow this
system to work with most microcomputer systems

As the line of a TV picture strobes across and down the In this mode of operation, the address buffers between
screen, it must lighten and darken at exactly the right the CRTC and the RAM are enabled (at zero level), and the
moment to build up a complete picture. Only two levels are data buffers into the RAM and the address buffers from the
used here: logical one, and logical zero, giving white and MPU are disabled. The RAM is also held in a "read"
black. These ones and noughts are stored in the 2513 read- condition, being a one on the read-write (R/VV) line. When
only memory employing it as a character generator, and it is the MPU wishes to address the RAM, the states of these
the CRTC which controls the exact moment at which these buffer -enables are changed to allow the MPU to read or
are available to be displayed on the TV screen. A TV line is write to or from the RAM. The RAN line is controlled
continuous and needs the ones and noughts in a sequential accordingly.
manner, hence the use of the "parallel -in serial -out' device, The final block of the system is a UHF modulator to allow
whose speed of transmission is determined by the TTL the VDU to interface to an unmodified TV set. The definition
oscillator. of the display is always partly degraded by this technique.
In order to send the correct character to any position on For those with a monitor or a modified TV set, a video output
the screen, the CRTC generates the addresses for the RAM is provided which gives a highly stable and clear display.
block which sends back the characters for display in the form
of ones and noughts along its data lines. These are latched CONTROL LINES
and form the address inputs for the 2513. The CRTC places The VDU -select line is decoded from the upper address
white regions between characters by disabling the 2513 in lines of the MPU system and is active -low. The enable line is
those time slots. a control generated by most MPU systems to enable only

Practical Electronics October 1978 1055

when the address information is valid, thus preventing a Fig. 2. Cursor control flowchart
false read or write. This line is fed from VMA & (1)2 in a 6800
system and is also active -low. RAN is generated by MPU
systems to distinguish between a read (R/VV= 1) and a write
(RAN = 0) operation.
This leaves only the CRTC control lines C9, C1, C2 and ST.
They are specific to this chip and allow hardware control of
the cursor (a flashing character permanently on display). The
cursor may be moved up, down, left or right, by applying the
appropriate ones and noughts on C9, C, and C2. ST is used to
inform the CRTC that a control word is present.

OPERATING SYSTEM
Displaying information on the screen is a very
straightforward operation with this VDU. Characters are
displayed by writing their ASCII codes to memory locations
in the VDU. The exact addresses involved depends upon
where in memory the VDU RAM has been placed.
It should be remembered that the display consists of
1024 ASCII characters arranged so that the top left position
on the screen is the lowest address in the block. Thus, a user
may decide to place this additional 1 kilobyte block of user
RAM at address 0000 to 03FF (hex), for instance. These
particular addresses are best used for other things in a 6800
system, however, and a better suggestion is to place it at,
say, 1000 to 13FF. This means that the ten lower address
lines, A, to A9 are necessary to distinguish between each
address on the screen. The upper six lines must be decoded
to address this particular block of memory as opposed to any
other. This occurs when A15 to A10 have values 000 100
respectively. That is, when the MPU places these six values
on the respective address lines, the VDU Select line must go
WRITE'SPACE"
low. The first 10 address lines of the MPU are fed to the TO ADDRESS
VDU and take care of addressing within the VDU RAM POINTED TO BY X
automatically.
A typical display operation is illustrated by the following
example. Suppose the word "hello" followed by spaces, is to INCREMENT X

be displayed on the top line. The letters of "hello" are first WRITE A TO
ADDRESS POINTED
converted into their hexadecimal equivalents in ASCII: TOBY X

H = 48 (hex)
E = 45 (hex)
L = 4C (hex)
0 = 4F (hex)
SPACE = 20 (hex)
A small program is now written to store 48, 45, 4C, 4C,
4F, in consecutive memory locations starting at 1000, in the
above system. This displays the word at top left of the INCREMENT X

screen. Another program is then written to store 20 in X SET EQUAL

locations 1005 through 103F. This fills the rest of the top TO START OF
line with blanks. In this way, any program, while running, NEXT LINE
CURSOR
simply stores the ASCII equivalents of its output somewhere RIGHT

in the VDU RAM. X SET EQUAL

TO START OF
Another important use of the VDU comes in program VDU RAM
writing. Several ways may be used to check on what has just CURSOR
been written. The program may simply be input to the MPU DOWN

system by a bootstrap loader. This is the type most

commonly found in MPU monitors.
A "dump" of the contents of a block of memory CURSOR
HOME LEFT
containing this program may then be displayed on the
screen for checking. Some monitors already contain a
formatted dump, and it is then simply a question of ensuring
that the VDU RAM is enabled at the correct addresses for
this monitor. The writing of this sort of software is quite
straightforward and well worthwhile. Another important
method of checking during program development is to
display the program one byte at a time as it is written. Fig. 3. Scrolling flowchart

1056 Practical Electronics October 1978

 COMPONENTS . .

Resistors
R1 8.2M0
R2, R3 5600 (2 off)
R4 47k0
R5, R11 1k0 (2 off)
R6 2200
R7 3.3k0
R8 1.2k0
R9 2.7k0
R10 1k0
(all 1W 5% carbon film)

Potentiometers

The experimental prototype VDU board. Next month a VR1 100k0 min vert preset
double sided p.c.b. layout will be published which VR2 1000 min vert preset
incorporates all refinements including the modulator
Capacitors
C1 0.22µF Disc ceramic
C2 100pF Sub min ceramic plate
C3 82pF Sub min ceramic plate
C4 33pF Sub min ceramic plate
PRACTICAL ELECTRONICS U 0 U C5 47pF Sub min ceramic plate
truttsittitittiRtitititt:Mtitttitttititm::: 10nF Disc ceramic
C6
16 LINES X 64 ASCII CHARACTERS
C7 33µF 10 volt Tantalum bead
FULL MEMORY NAPPING FACILITIES C8 220µF 16 volt electrolytic
FULLY BUS COMPATIBLE C9 47µF tant bead (10V)
INEXPENSIVE LON CHIP COUNT
EXTRA It BYTES OF USER RAM
VIDEO OR DIRECT T V OUTPUT
Semiconductors
11:11:117littinfttiltftltWitinttnIttitttitt
$ FULL CHARACTER SET $
IC1 SFF96364 plus socket
123$567898,48W(4 IC2-1C9 2102LF (350nS118 off)
IC10 2513 (single supply type) plus socket
ABCDEFGHIJKLMNOPORSTUROXYZ IC11 74174
IC12 74165
IC13-1C16 81 LS97 14 off)
IC17 74163
IC18 74LS132
1C19 7402
TR1 BC184
Two examples of the type of display attainable TR2 2N3663
XTAL 1 1MHz

Miscellaneous
SK1 chassis mounted coaxial TV socket plus nuts and
bolts for fixing
Two pieces of Veroboard 10.1in matrix)
46 x 25mm each
PP3 battery connector
4844 8A 0.5 metre of 8 -way ribbon cable
8041 88 Pins for through -board connection
6082 87
8443 AO PROGRAM lEVELOPNENT
Switches: S1 s.p.d.t. S2 s.p.s.t.
$484 18
INNS ID USING
8846 HO Constructor's Note
4887
A complete kit of parts including a drilled plated
A7 PE VDU
6488 64
8489 27 through p.c.b. will be obtainable from Technomatic
4604 3F
4848 FF
(01-204 4333). Details next Month.
4840 Ef A limited number of assembled and tested boards
4444_ will also be available exclusively from Technomatic
Ltd., 17 Burnley Road, London NW10.

Practical Electronics October 1978

Normally this would be done as follows. A byte is loaded
from the keyboard into some memory location. A jump to a
display routine is then performed, which puts the address
just loaded plus its old and new contents onto the screen. Table 1. Cursor control codes
This is repeated until some control character tells the load
routine to end.
The importance of a cursor, plus good screen
management or formatting in this process cannot be over
emphasised. Fortunately, the CTRC has a set of quite OPERATION co Cl C2
sophisticated cursor control commands, as previously cursor home 0 0 0
mentioned. cursor home left 0 0
A particularly effective and striking feature of the CRTC is line feed 0 0
its hardware scrolling function. If a Cursor Down (line -feed) cursor left 0 0
command is given when the cursor is on the bottom line, the cursor up 1 0
entire screen's contents jump up one line with the top line cursor right 1 1

jumping to the bottom. This also occurs if Cursor Right

operation is commanded with the cursor in the last position
on the screen.
After such a scrolling function, the lowest address of the
1 kilobyte RAM is no longer displayed at the screen's top left. The speed of operation of your MPU decides whether you
Instead, it is at the extreme left of the lowest line. A write should load A in the above with 00 (hex) initially or some
operation to this address causes a character to appear in a higher number which will revert to 00 in fewer loop steps. A
position on the screen dependent upon the number of scrolls simple VDU routine is shown in Fig. 3. This routine assumes
which has been performed. However, the Cursor Home that a character to be displayed is stored in ASCII code in a
operation forces the whole display to "de -scroll" and the register (called the A register here). The cursor position
display reverts to normal, with the cursor at top left. address is also assumed to be stored in a register (called the
The cursor operation required at any time is converted X register). Characters are written to the bottom of the
into a code of ones and noughts and applied to Co, C, and C2 display and a carriage return operation causes the screen to
according to Table 1. scroll upwards. Spaces are then written to the end of the
The technical specifications of the CRTC demand that the current line, and the cursor is moved to the start of the line.
ST control line (normally in a high state) should complete a Information thus enters on the bottom line, following the
low pulse of at least li.ts a minimum of 8.3ms after any code cursor, and then scrolls up the screen.
is applied to Co, CI and C2 (apart from Cursor Home). This This completes the description of the system and in the
informs the CRTC of the presence of a cursor control word. next issue, constructional details and setting up procedures
The Cursor Home command requires at least 132ms will be given.
between the control word and the ST pulse. This is best The reader is urged to obtain a copy of the data sheet for
done in software by the simple loop shown in Fig. 2. the CRTC and 2513 chips for additional information.

0000
0000

NEXT MONTH: Assembly

VDU of p.c.b. and construction of
high density RAM module.

LINEAR CAPACITANCE METER (June 1978)

paws mum Unfortunately another error in this article has come to

light. IC4 and IC7 should be wired between +6V and -6V.
In Fig. 4 they are shown connected to OV.

DIMWIT (July 1978) KILN CONTROLLER (June 1978)

Some constructors may find that during the period In Fig. 2 page 733 the value of R8 should be 101d2 and
between the dim-out sequence and when the relay drops the voltage rating of C2 in Fig. 4 should be 450V.
out, the lamp flickers. A cure for this is to shunt the I.d.r. The setting up procedure on page 734 refers to the
(R13) with a 220k resistor. output of IC2 instead of IC3.

1058 Practical Electronics October 1978

nen cm o rril-no
Be the first one down your street to
land on the moon. Sixty seconds to
make a gentle landing with only a
limited amount of fuel. You have a
readout of height, velocity and fuel
remaining but if your efforts fail you
can still push the panic button and
run on medicinal whisky.
POWER FETS
A feature on the new semiconductor technology which is challenging
the supremacy of the bipolar transistor in many power applications.
CAR DEVICES
8 Page Supplement
 Fuel I.

Consumption
Meter J McCARTHV

This unit does not show the average m.p.g., but gives an instan-
taneous fuel consumption related factor. You can check your driving
efficiency. As your foot goes down on the accelerator, down goes the
m.p.g., and up it comes again when your foot does!

111111111111E1 III 4111111111111

 THIS article describes a fuel consumption meter which The signals applied to this module, in relation to the signal
has been operating successfully for many months. The received from the vehicle sensors, relative to time, are in Fig.
attributes of the system are: 4, which is not necessarily to scale. For each rotation of the
(a) Two digit digital display speedometer cable, one pulse is applied to the gated speedo
(b) Mainly low -price TTL input, until the fuel pump operates, at which point the strobe
(c) Interfaces to the car via a simple connection to the SU and reset lines are sequentially pulsed in order to display the
electric fuel pump, and an easy modification to the count since the last pump operation, and to reinitialise the
car's speedometer. counters.
Fig. 3(b) shows the second module; this circuit matches
An SU electric fuel pump may be fitted to any car using a and converts the signals obtained from the speedometer and
mechanical fuel pump, provided that the former can provide the fuel pump sensors into those suitable for TTL logic.
the fuel at a satisfactory rate. In the author's case, a 1725cc
Hillman Hunter was fitted with a fuel pump borrowed from SPEEDOMETER SENSOR
and aged side-valve Morris Minor. The Hunter never showed At this point, it is necessary to describe the method of
any signs of fuel starvation despite very hard driving. Fig. 2 application to the speedometer of a sensor. The method
shows a simplified diagram of such a pump. As the pump used by the author, which should be applicable to the
operates, the voltage at point "A" alternates between +12V majority of cars, was to mount a photo -sensitive device in
and OV (for -ve earth vehicles). the rear of the speedo in such a way that light is reflected
The measurement system may conveniently be from the speedometer illuminating bulb via a part of the
considered as two interconnected sections, as depicted in rotating mechanism, onto the photo -device. The point at
Fig. 1. Referring to this diagram, the distance monitor counts
pulses derived from the speedometer, whilst pulses at a
slower repetition rate derived from the fuel pump cause the Fig. 1. Simplified block diagram of Fuel Consumption
generation of a series of internal control pulses which halt Meter
the speedometer counting process, store and display the
count to date, and reset the counter. This effectively
generates a measure of distance covered per operation of DISTANCE 7 SEGMENT
SPEEDO
fuel pump, which it may be noted is of the same dimensions SENSE MONITOR DISPLAYS
as miles per gallon, or for that matter, kilometres per litre,
although it is clearly not in these units. Fig. 3(a) shows the
counter module circuit, which utilises a total of six TTL chips
which drive a pair of 3015F seven -segment displays. Its
function is as follows: Provided that the reset line is kept
low, pulses into the gated speedo input, or to be more FUEL PUMP FUEL
SENSE
specific, negative going edges, will cause the two tandemed MONITOR

7490s to count. Pulses to the strobe cause the 7475s to

latch their outputs to the count generated at their inputs by
the 7490s. The 7475s outputs are converted by a pair of
7447s into seven -segment display code.
 FUEL OUT
COMPONENTS . . .

JI
±I1\

Resistors
R1, R3 2700 (2 off)
R2
DIAPHRAGM SOLENOID R4 270k0
CHASSIS
PUMP SENSE R5, R6 240k0 2% (2 off)
TAKE OFF
10y) R7 6.21(02%
R8 27kfl
All resistors iW 5% unless otherwise stated.
FUEL IN

Fig. 2. Diagram shows the fundamental arrangement Potentiometers

of an electric fuel pump, and how the sense signal is VR 1, VR3 1001(0 vertical preset (2 off)
derived. One-way valves direct the flow of fuel as the VR2 1 MO vertical preset
diaphragm oscillates
which this is mounted has to be carefully selected, and it
may be necessary to paint parts of the internal workings of Capacitors
the speedometer with matt -black paint. It is also necessary C1, C2, C8, C9, C10 1nF (5 off)
to make a minor change to the speedometer illumination C3 0.01µF
system, entailing severing the wire connecting the C4 100µF/20V electrolytic
C5 10nF
speedometer bulb to the sidelight system, and connecting it C6 lOnF
instead to the ignition switch, such that it is on, whenever C7 22µF
the ignition is on. The photo -device is then connected to the
module of Fig. 3(b) via screened cable. This precaution has
been found to be essential in view of the high impedance Transistors and Diodes
nature of the phototransistor, when no light is falling on it. TR1,TR2 0C200 (2 off)
The current changes caused within the phototransistor TR3 2N3705
due to changes in the incident light are then used to drive a TR4 BP101, TDB7805T or equivalent
p.n.p. Darlington pair, the output from which is taken to a D1, D2, D3 0A202 (3 off)
variable Schmitt trigger comprising a 741 with adjustable
positive feedback, a level -shifting n.p.n. transistor, and finally
Displays
a 7413 to generate suitable TTL levels, The setting of the X1 X2 3015F (2 off)
three variable resistors will be described later. The signals
from this section of the unit are then sent to the counter
module for processing. Integrated Circuits
IC1,1C2, IC8 7490(3 off)
FUEL PUMP IC3, IC4 7475 (2 off)
The pulses from the fuel pump which have additional IC5, IC6 7447(2 off)"
unwanted spikes in both the positive and negative sense, are 1C7 7413
first clamped to TTL levels by a pair of diodes, one of which IC9 7400
prevents negative puises from entering the remainder of the IC10 7404
circuitry, the other of which clamps the input level to less IC11 74123
IC12 741
than 5V. The pulses then go to a pair of retriggerable IC13 7805 regulator
monostables, held in one package, the 74123. The two
monostable multivibrators have periods of T1 and T2 where
T1 is very much greater than T2. The output of the Miscellaneous
monostable of period T2 is used to drive the subsequent Three way plug and socket for sensor inputs. Metal case
circuitry, while the output of the other monostable is used to (prototype housed in box 162 x 70 x 50mm). Plug and
inhibit false triggering caused by contact bounce, ringing and socket for 12V input. Veroboard. On/off switch. Inte-
so on. grated circuit holders if desired. Polarised display filter
The subsequent circuitry comprises a pulse sequence (for digital version).
generator to generate the reset and latch strobe pulses, and Not needed for meter display
to inhibit the input of speedometer derived pulses. The heart
of this system comprises a divide -by -eight counter, part of a
Constructor's Note
7490 (IC8) and a clock oscillator, part of 7413 (IC9). A pulse The BP101 is available from Electrovalue. 0C200
from the monostable driver will force the counter to reset, transistors are available from Watford Electronics,
which allows the oscillator to function. This causes the
counter to count from zero to four, in so doing, generating
and Semiconductors Supplies, Orchard Works,
Church Lane, Wallington, Surrey, SM6 7N F.
the required control pulses. When the counter achieves a
count of four, the rising of IC8 pin 9 output inhibits the
function of the clock oscillator.

1062 Practical Electronics October 1978

OATED
SPEEDO *, Cl
INPUT
+5V
1nF

16 13 15

RESET 0
SUPPLY PINS
OV +5V
ICI 10 5

IC2 10 5

IC3 12 S

STROBE 0 IC4 12 5

ICS 16

IC6 16

14

41=1111M
X2 3015F

1nF

Fig. 3(a). Counter module circuit (built on separate board)

+58
TR2
0C200
R6 24060 TR3
BP101 VR1 7 IC12 VR3
SPEEDO SENSE 10060 741
2N3705
R5 24060
10060

MOUNTED IN VR2
SPEEDO

+5V +5V
101 13
1111 IC10
IIC9 IC10
R2 R7 16 11
2460 6.260
RI D2
°RESET
R8 2
PUMP SENSE D3 27 kfl
17404 1,67404
C6 0A202 C8
2700 OA 202
6 IC11 IC8 1/47400 1

14
10 nF 7490
74123 14

DI 710A 202 C7 22p

5
IC9 IC10
111111= IC10
10 I
STROBE
1 161 5D:36 5

1/0400 C9 1n 167404

TO GATED 1,67404
SPEEDO
INPUT +SV 47
1nF
IC7 IC7
12
1/27413 IC10 1/27413
2 13
6 a OUT
10 10 10 1
5
R3 2700 10nF
SPEEDO CS
1/67404 ILLUMINA-
TION BULB
RED SPOT OUTC°*1
01pF
...:11:- IN
+12V
0C200 13P101 7805 FROM IGNITION
SWITCH

Fig. 3(b). Interfacing module circuit diagram. This part of the system matches the sense signals to the TTL
SPEEDO
SENSE

PUMP
SENSE

GATED
SPEEDO
INPUT

STROBE

RESET

TIME

Fig. 4. Sensor and control signals relative to time. These are

not to scale The use of a metal case is advisable for effective screening;
the 5V regulator can then be mounted on the rear of the unit
for excellent cooling. The driver will probably be most
ANALOGUE DISPLAY curious about the fuel consumption reading when
accelerating hard; a time when increased concentration on
The author's unit employs a pair of seven -segment the road is required, and so care should be taken in the use
displays, but it might be felt preferable by some constructors on this instrument.
to use an anologue meter display. These may easily be done
by replacing the displays and their associated 7447s with
the circuit of Fig. 5. In this circuit, the inverted outputs of the
two 7475s are used to drive a 6 -bit resistive digital to
analogue converter, the resulting current from which is COMPONENTS . . .
amplified by TR4, and used to drive a 1 mA meter
movement. The emitter of TR4 is set to around 2.2V below
Vcc by the effect of the three diodes D3, D4 and D5 and FOR METER DISPLAY
Resistors
R8 390k0 + 1080
R9 47k0 + 2.7k0
Vcc +5V
VIRMINIMMIN
390811 R8 1080 R10 180k0 + 18k0
D3 R11 1001(0
14
4780 R9 27k0 1N4148 R12 470k0 + 27k0
04 (CAN BE R13 1 MI (2 off)
252 ZENERI
1C3 18080 R10 18k0 R14 2700
1
D5
VR4 R15 2-7k0
R11

Ski) Potentiometers
10080 TR4 VR4 5k0 preset
2N4291
D3, D4, D5 1N4148 (3 off)
470811 R12 2780
or 2VZ Zener (1 off)
Meter
R14 2700 R15 C 2.780 M1 1 mA f.s.d.
IC4

R13
1mA F.S.D.

CONSTRUCTION
Fig. 5. Circuit diagram of meter display circuit. Devices The circuit layout is in no way critical, and in the author's
marked with an asterisk in the main components list will not case, the equipment was built on two small sheets of
be necessary if this readout system is used Veroboard, with each board corresponding to one of the
modules described previously. The above having been said,
it is important to observe two important rules: The
R15. This ensures minimum current flow when the outputs decoupling capacitors on the 7490s on the counter module
of the 7475s are high, thereby obviating the necessity of a board are essential to the counter chips' correct operation.
set zero adjustment. VR4 is used to set the full-scale They should be connected as closely as possible to the chip
deflection value. This should be initially set to its maximum supply pins. In view of the electrically noisy environment
value, and when adjustment of the rest of the equipment has within a car, due to ignition, and other radiation, the
been made as next described, set to give the desired full- equipment should be constructed within an earthed metal
scale reading in use. box; failure to do so may result in spurious operation.

1064 Practical Electronics October 1978

 The author's Fuel Consump-
tion Meter circuit was laid out
on two pieces of Veroboard
mounted one behind the
other. Component layout is
non -critical, and this
photograph shows the basic
arrangement of the counter
section of the prototype unit.

Interfacing section circuit

board. Use Fig. 3 for interwir-
ing. This board should be
mounted so that the displays
show through the front panel
directly

SETTING UP the 7493 does not halt in the mentioned rest state,
The only specific adjustment required in the system is that something in this area is not in order and the circuitry should
relating to the circuitry interfacing the speedometer to the be checked. If all is well, transfer the test meter probe to the
TTL, and three preset adjustments have been found input of the 7413, and reduce the value of VR3 until the
necessary. pulsations appear from the output of the 741, and then at
Adjustment may most easily be done with the equipment the output of the 7413. The equipment is now ready for use.
in the car, and both driving wheels securely jacked -up clear
of the road. With the engine started and idling slightly faster INTERPRETING THE RESULTS
than normal, gently engage first gear. The three preset During normal driving, the readings presented by the
potentiometers should be initially set as follows: equipment will fluctuate with changes in fuel consumption.
VR 1 mid -position. It should be noted that two sources of inaccuracy can occur.
VR2 maximum resistance. The first of these occurs because the float -chamber
VR3 maximum resistance. systems of most carburettors are gravity operated, and any
A test meter should be set to around the 5V d.c. range, violent disturbance in the car's motion, such as violent
and connected to the output of the 741. braking or cornering will affect the amount of petrol allowed
VR1 should be adjusted in either direction as necessary into the float -chamber by the needle -valve, causing a
until the meter reading pulsates at a speed proportional to momentary upset in the readings obtained.
the speedometer reading. VR2 should then be adjusted until Secondly, as is well known by Morris Minor, and
the pulsations just stop, and then increased by about 10 per doubtless other drivers, a marked lowering of the level of
cent. VR1 should be adjusted to the middle position of the fuel in the petrol tank causes the pump to operate very
range in which speedometer pulses are detected. So far, a rapidly as air, rather than petrol is ingested. The settings of
centre point for the input pulses has now been determined, the timing components on the 74123 is such that a cycle
and by setting the positive feedback to the maximum during which air is ingested occurs before the 74123 pulse
acceptable, any rough tops to the waveform will be "ironed of time T1 has finished, thus ensuring that the pulses from
out". The number held by IC10 should now be checked; this the pump are ignored when air is being drawn in. Accuracy is
should be the value 4. If this is not the case, momentarily still effected by this phenomenon however, and the fuel level
trigger the 74123 by connecting the pump sense wire to should not be allowed to fall this low in normal running if
earth for a brief period. If after a very short period of time, accurate results are required from the equipment.

Practical Electronics October 1978 1065

impedance 01 BY TOBY BAILEY & BOB WHITAKER

WHEN learning about electronics, capacitor and an inductor which both and imaginary part = 4. This line has
one of the earliest things that we have an impedance of, say, 1012 at a a certain length "r", and makes a
find is that for a resistor the voltage particular frequency that we shall certain angle to the real axis "0".
across it and the current driven through apply. If we connect these compo- Note that the complex number can be
it are related by Ohm's Law nents in series and apply an a.c. specified in terms of r and 0, and these
E == I R voltage we might expect that the two numbers completely specify a
impedance of the combination would particular complex number, just as x
where E is the voltage across a resistor be 20u, but this is not the case. and y do.
with resistance R and I is the current. The total impedance is in fact zero! Given the representation of a
These three quantities are generally Furthermore if we connect the com- complex number as x + yi or as an r
measured in volts, ohms and amps
ponents in parallel the impedance is and a 0, it is always possible to convert
respectively. We then discover that not 5s-2, it is infinitely large. from one representation to the other.
capacitors and inductors produce a The above example demonstrates
similar relationship, which is written that we require rather more information
as E IZ where Z is the impedance of if we want to calculate the impedance
the component and E and are as-
I
of a combination of elements.
sumed to be sinusoidally varying a.c.
voltage and current respectively.
The reason for this assumption is COMPLEX NUMBERS
that non -sinusoidal waveforms are We now introduce the concept of a
effectively a mixture of more than one complex number which consists of
frequency. two parts: called the real part and the
many components varies with fre- imaginary part. A complex number is
quency, the current flowing will not written like this
then be directly proportional to the x + yi
driving voltage. It is worthwhile noting, Here x is the real part and consists of
as an aside, that the way that non - a real number, whilst y is the imaginary
sinusoidal waveforms are dealt with part. iis the important symbol (j is
is to break them up into the sum of often used instead) which represents
sinusoidal parts, each of a different a number which when squared gives
frequency. Each of these parts can minus one
then be dealt with using E = IZ, the i i -1
current flowing can then be recon- Applying Pythagoras' Theorem to
structed by summing the currents of If that is a little difficult to conceive of Fig. 1
the individual parts. it doesn't matter-just think of it as a
symbol which labels the imaginary r = ,/x2 + y2
In order to use the above formula we
need to know the value of the imped- part of the complex number. Examples This is by far the most often needed
ance Z for the circuit. For a capacitor of complex numbers are: 3 + 4i, conversion. For the more mathe-
the impedance (often called the 10 -3i, -3.6 104 + 6.7i. Real num- matically minded we will give the other
reactance) is given by 1/27rfC, where bers such as -7 and 43.6 may also be formulae
fis the frequency of the signal in thought of as complex numbers r cos0 = x
hertz, C is the capacitance of the whose imaginary part is zero. Similarly r sin0 = y
capacitor in farads (a unit which we there are numbers such as 6i, -0.2i tan0 = y/x
soon find out is about a million times or even i (which is the same as 1i) in Of these the last is the most important.
larger than is useful), Tr is 3.1416. which the real part is zero. Addition of two complex numbers
Similarly the impedance of an inductor simply involves adding the real and
is 2irfL where L is the inductance of ARITHMETIC the imaginary parts separately as
the inductor in henrys. Fig. 1 demonstrates a way in which shown below
Given this starting point it soon complex numbers can be shown on a (x + yi) + (a + bi) = (x + a) + (y + b)i
becomes apparent that there is much diagram. In the figure the complex
more to the impedance of capacitors number is 3 + 4i. It is represented by For subtraction you just subtract
and inductors than their simple a line which goes from the origin of real and imaginary parts separately-
numerical value. Consider, for ex- co-ordinates (marked 0) to the point be careful to get the signs right!
ample, the case when we have a which lies on the lines; real part = 3 (x + yi) - (a + bi) = (x - a) + (y - b)i

1066 Practical Electronics October 1978

 Multiplication is a little more oscillating voltages and currents are
complicated also represented by complex numbers.
(x + yi) . (a + bi) - Using the arithmetic of complex
(xa - yb) + (xb + ay)i numbers that we have described, it is
now possible to use Ohm's law to TIME
Unfortunately dividing complex give the correct answer and we can
numbers is more difficult than the combine impedances in the same way
preceding cases-hopefully the follow- as we used to combine resistances.
ing steps should make the process Let's see how this works. of LEADS IbI BY 6e
clear. Assume we want to evaulate Resistors have no imaginary part
(i)
x + yi to their impedance, it is just their
a + bi resistance R.
Capacitors have no real part to their v.
f:
First we multiply both the top and the 3

impedance, it is given by -i/27rfC. . /,,,,,,,,,,..,

2 lal
bottom of this expression by a - bi. The symbols all have the same lb)
Since this is the same as multiplying
meanings as before. REAL
the original expression by one, our Inductors too have no real part to
1 2 3 4 5 6

division can now be written as B IS THE PHASE LEAD ANGLE

their impedance, it is given by 27rfLi. Fig. 3
(x + yi) . (a - bi) It is easiest to represent voltages
(a + bi) . (a - bi) and currents in r and 0 notation.
If we now multiply out (a + bi) .
First it is essential that you know
(a - bi) we get a2 + b2 which has no aboyt the phase difference between
imaginary part at all, so our expres- two sinusoidal waveforms of the same TUNED CIRCUIT
sion is the same as: frequency.
The phase difference is given by The complex impedance of the
(x + yi) . (a - bi) the distance between the peaks of the series tuned circuit in Fig. 4 (a) is
a2 + b2 two waveforms and is specified by an found simply by adding together the
angle which is worked out by defining complex impedances of the capacitor
and we know how to multiply the top and the inductor to get
to get the angle between two successive
(xa + yb) + (ya - xb)i peaks of the same wave to be 360.
(27rfL
Reference to Fig. 2 should make this 27rfC i
a2 + b2 clearer.
and this is the same as QUANTITY
ONE CYCLE TWO SINUSOIDALLY
(xa + yb) (ya - bx) i OF 360' VARYING QUANTITIES

a2 + b2 a2 + b2
There is just one more thing before
we finish our maths lesson and that
is how to multiply and divide complex
numbers when they are in r and 0
AIME
wqr TIME

form. This is simpler than for numbers seTWA

in x + yi form: to multiply you multiply Note that the impedance still has no
PHASE DIFFERENCE
the "r"s and add the "0"s; to divide OF 90. real part. Hence in r and 0 form it has
you divide the "r"s and subtract the Fig. 2
"0"s. r= (27rfL and 0 = 90°.
To describe a voltage or current in 27rfC)
In theseexamples the complex
numbers are written as (r,0); thus terms of a complex number it is You may notice that r might be
(2,36-) stands for the complex number necessary to take one waveform in the negative in the above formula, in which
with r = 2 and 0 = 36'. circuit as a reference to which all the case 0 would be 270'-but negative r
(i) (3,15') . (4, - 12') - (3 . 4,15° others will be referred. This reference in the direction of 90' is the same as
-12') (12,3°) value has no imaginary part, and its positive r in the direction of 270°.
(ii) (16,186°) (f, -26') -= (16.f,
.
real part is just its peak value. All other It isn't usually worth bothering about
186' -26°) = (8,160') voltages or currents are represented these things, they almost always work
(iii) 2,17° 2
in r and 0 notation by a complex out alright in the end!
= -10' number with r equal to the peak value Now suppose that we want to know
5,27
and 0 equal to the angle by which the what current flows in the circuit. We
But remember that 360' is a full waveform "leads" the reference wave- know that E= IZ, so I = E/Z. Choose
circle, so that -10' is the same as form. By leads we mean that the the input voltage to be the reference
2 2 angle is measured from a peak of quantity for the circuit-it will then
+350' so 5, -10' = 350' the wave to the next peak in time of have r -V (the peak value) and
the reference wave. See Fig. 3 for an 0 = 0'. Towork out the current
It is now time to use these numbers. example of this. flowing we divide E by Z, remembering
With the set up we have just des- to divide the "r"s and subtract the
COMPLEX IMPEDANCES cribed, almost anything that you "O"s. So I has
Any impedance which is a combina- could have done with resistances and V
tion of resistances, capacitances and d.c. voltages can now be done for and 0 - 0-90 '=
inductances can be represented as impedances and sinusoidal (i.e. one 2rcf L-
1

one complex number. Sinusoidally frequency) a.c. voltages. 2 rcfC

Practical Electronics October 1978 1067

So the current is 90' out of phase with is given by What do all these complicated -
the voltage, remembering that leading looking formulae mean as regards the
by -90' is the same as lagging by I=
V
Z
- Vin
1
performance? Well, when the fre-
90'. We have a rather peculiar expres- R- quency is very high the
sion for the peak value of the current 2nfC
1
(r). Notice how this expression is Now the output voltage is produced
positive for high frequencies but by the current flowing through the 4n2f2C2
I

negative for low ones. Thus the resistor R so, using Ohm's Law, we Voui
arrangement of the waveforms in term is very small and so - becomes
obtain Viii
VinR very close to one. This indicates that
4
Voui =
R- 1
1
high frequencies pass through the
A 2irfC filter almost unobstructed. In contrast,
/ To evaluate this we had better put it when f is very small the
/ S
%1
TIME into r and 0 form. V,,,R is simple- 1

since it is just an ordinary number 4n2f2C2

with no imaginary part it has r = VinR term is going to be far larger than the
and 0 = 0°. To convert the bottom R2 term so we can ignore the R2 term
half of the expression we need to use without too much loss of accuracy.
I LEADS V BY 90°
the formulae for r and 0 in terms of We then have
Fig. 4 (b) x and y that we mentioned earlier:
Vow.
namely r = J x2 + y2 and tan° = y/x - 2nfRC
Fig. 4 (b) is only valid for high frequen- (this last part can be done by scale Vin 1

cies. As f decreases, suddenly be- I

diagram). Putting the x and y values of 4n2f2C2
comes very large (when the bottom of
the expression for r becomes zero) 1 . Voutfigure
R+ I Notice that the halves every
and then smaller again. However r is 2nfC Vin
now negative so the phase changes into these formulae gives the value of time the frequency halves. This sort
by 180`-this is the same as saying r to be of relationship is best shown on a
that the waveform of the current be- 1
decibels versus logarithmic frequency
comes inverted. r = R2 + plot as shown in Fig. 6 (a).
In practical circuits of this nature
there is always some resistance and 0 is going to be the angle for which 0

present so the change occurs gradu- -1 5

ally. Note that the impedance of this F.6. 10

circuit goes to zero when Using the rule for division in r and 0
Z
0
15

5 20
1 form we can now calculate the value of
2nfL 25
2nfC \tout 30
the r part is
i.e. when yin 35

f= 1 R
10Hz 100Hz 1kHz 10kHz 100kHz
2n,,/ LC r= R2 + 4n2f2C2
1 FREQUENCY

which is the well known resonant

frequency. Fig. 6 (a)
and the 0 part is minus the angle for
which
-1 Taking OdB at the input level, the
y
SIMPLE R.C. CIRCUIT x 2nfRC
output level of the filter is fairly con-
The circuit shown in Fig. 5 is a stant down to just above the break
very basic high pass filter. To find the -if you draw a diagram you can see point: the output then curves down,
current which flows we need to know that this is the same as the angle for finally falling off at about 6dB per
the impedance of the combination, which octave (halving of frequency) which is
which is given by y 1 20dB per decade.
x 27rfRC We have not yet used the informa-
-1
Z=R+
2nfC
1) = R-2nfCi 1
The r value gives us the amount by tion we have calculated about 0. For
which the amplitude of the voltage is actual values of R,C and f, 0 can be
decreased. When evaluated either by drawing a diagram
1 or by working out
V0LA
R2 =_
4n2f2C2 0 = arctan
1

this attenuation factor is about .707 (or, 2nfRC

using the decibel scale, about -3dB). on a scientific calculator. We can see
Rearranging this formula and getting roughly what is going to happen: at
rid of all the squares gives very high frequencies when the filter
1
is passing almost all of the input
Choosing Vin to be the reference f voltage, y/x is very small which means
quantity (which, you should remember 2nRC
that the output voltage has almost the
means that r = Vin and 0 = 0°) we This is often called the break point for same phase as the input voltage. As
can then say that the current flowing the filter. the frequency decreases it will reach

1068 Practical Electronics October 1978

the break point where which we want to equal A graph of this is the attenuation of
1 1
the filter, as shown in Fig. 8 (a).
-1
2nfRC 10
-this means that the output will lead Choose as fairly sensible values R1 s

the input by 45°. As the frequency S2, 1k11. Whether these are
R2=9k z 10

keeps on decreasing the phase lead sensible will, of course, depend on 15

will continue increasing, getting ever the impedance of the source we are z 20
nearer to 90° but never quite getting using to drive the filter and the imped- 25

there as shown in Fig. 6 (b). ance that is being driven by the filter. 30
10Hz 100Hz 1kHz 10kHz 100kHz
Say for the sake of simplicity that the FREQUENCY
90.
driving impedance is a few ohms and
60
that the driven impedance is at least Fig. 8 (a)
70.
8 60 several tens of kilohms. Now down
to work: PHASE PERFORMANCE
50.

40.
To get some idea of how the phase
8
30
Using the symbol R, IC to mean the difference between the input and the
20
impedance of the parallel combination output varies with frequency we see
10.
of R1 and C we have that at high frequencies the capacitor
0. Vcint R2
is going to have far more effect than
10Hz 100Hz 1kHz 10kHz 100kHz
R2 ± R11I C
R1 and so the phase shift will go to
Vin
FREQUENCY zero, just as it did for the simple high-
Fig. 6 (b) But R2 = 1W and R1 = 9k S2 so pass filter. Also at very low frequencies
-1 the effect of the capacitor will be
When working with filters such as 9000 negligible and the phase shift will go
27rfC)
this one, it is generally true that the R,IIC =
I
to zero again. What happens in be-
attenuation versus frequency graphs 1
tween? If we substitute the value for
(on logarithmic scales) can be simpli- 9000 - 27fC i
the capacitance into
fied considerably. To do this you just and \tout 5
assume that the response is flat 5 90000
down to the break point, whereupon 90000 -7-R-6 I V,s 7rfC I

your
it falls off immediately at a rate of 50
6dB per octave = 20 dB per decade.
This approximation is shown dotted
Vin
90000 -0 i 7rfC we end up with
90000 - i

in Fig. 6 (a)-the approximation is very The "r part" of this expression can be Von, 316
accurate except for a decade or so found by dividing the r part of the top
around the break point when it can be Vin
by the r part of the bottom
up to 30 per cent out. 3160
1- i

j(90000)2 + )2
MORE COMPLICATED 1
From this we can work out the phase
FILTERS r=
shift for any frequency: for example
As a slightly more complicated 900002 + 50 )2 at 1kHz we have
example let us try to design a filter 7rfC
which passes high frequencies un- 1 - 0.316 i
Von,
since we require this to be equivalent
attenuated and attenuates low fre- to an attenuation of 10dB when 1 - 3.16
Vin i

quencies by 10. We want the middle f = 1kHz and 10dB is a voltage ratio Now 0 for 1 - 0.316i is about - 174W
point to be at 1kHz (the full attenuation of ARE, : 1. and 0 for 1 - 3.16i is about - 721',
is 20dB so call the mid point the 10dB Square both sides and multiply out so 0 for
attenuation point). We would also which gives Vont
like some idea of the phase perform- 2500 - 250 = 174° - (- 72 f)= 55'
9 x 81 x 108 -- Vin
ance. n2f2C2
R1
this is for f = 1kHz so
Yin 60
2250
C2 - so*
9 x 81 x 108 x 72 x 106 co*

= 3.127 x 10-15 30
20.
and finally we get to the value of the
10
capacitance C = 5.6 x 10-8 farads =
0
0.056/7f. If we substitute this value 10Hz 100Hz 1kHz 10kHz 100kHz
into the original formula for the r part FREQUENCY

The obvious way to do this is shown we get Fig. 8 (b)

in Fig. 7. At very low frequencies the 8.1 + 1014 105
effect of the capacitor is insignificant 4/(90000)2 + f2 f2 In fact this is the maximum phase
so shift for any frequency. A graph of
Vout R2 8.1 x 1016 107 phase shift versus frequency is also
4/(90000)2 + f2 f2
Vtn - R, + R, shown on Fig. 8 (b).

Practical Electronics October 1978 1069

High Performance
POWER
SUPPLY
UNIT
THIS article describes a high performance power supply
with voltage control down to zero (yes, zero, not two and
R.Lawrence B.Sc.
The resistors R11 and R12 determine the gain, and this is
given by:
a half volts or five and a quarter or, as in the case of many R 1- 1 +R12
supplies, whatever the Zener voltage used in the system
happens to be) and current limit from a few milliamps to R11
several amps. which can be re -written in terms of Vref ( 11 .2V), and the out-
This ability to have current limit down to such low values put voltage Vou, (30V) as the ratio of the two resistors:
allows one to, for example, work with low power circuitry R11 Vref
knowing that even if something drastic happens nothing will
R12 Vou, - Vrat
be destroyed. One can even use this facility for measuring
the values of larger electrolytic capacitors!
PREFERRED VALUES
Two preferred values which give this ratio whilst at the
same time approximately maintaining an equivalent
. I impedance looking back from either the inverting or non -
inverting inputs of the op amp (this keeps temperature drift
Voltage Control 0-30V effects in the input bias currents common -mode and
Current Control 2mA-2A therefore self -cancelling) are 33k0 and 56ka
Output Resistance Less than 0.0010
Ripple and Noise Less than 1 mV ADVANTAGES
Line Regulation Less than 0 001% One of the advantages of using a "power amplifier" -type
L.e.d. indicator current limit mode system in the voltage section is that the control of output
Sharp voltage/current mode transition voltage down to zero can be achieved easily. Other designs
Instant switch off allow this to be performed but solutions sometimes can
1 appear somewhat contrived. With the amplifier system zero
input means zero output.
CIRCUIT ACTION For perfectionists a preset has been provided which
The reference voltage is generated in the circuitry around allows one to trim out any remaining millivolts which can be
IC1 (see Fig. 1). D5 is a 5.6V Zener diode run at its zero caused by offset in the 741 or possibly the voltage control
temperature coefficient current. Values of most Zener series potentiometer not yielding exactly zero output voltage when
(BZY88 in particular) exhibit positive temperature coefficient turned fully anti -clockwise.
below 5.6V and varying degrees of negative t.c. above this
value. CURRENT LIMIT SYSTEM
R5 and R6 set the output of the reference generator at The current limit system sets the maximum output current
twice the Zener voltage and in addition a low output available from the p.s.u. and also provides an indication that
impedance feed to the rest of the p.s.u. is guaranteed by the the unit has shifted from constant voltage mode to constant
high degree of feedback employed. current mode.
The circuit operates as follows; the output of the op amp Current limit comes into operation when the voltage
IC1 increases until D8 conducts, whereupon the circuit across a sensing resistor (R7) reaches a predetermined
stabilises with the Zener voltage appearing across R5. value. This value is set by VR3 and is derived from the
Negligible current flows into the non -inverting input of IC1 reference voltage line from IC1.
and therefore all the current in R5 flows into R6 yielding
twice the Zener voltage at the output of IC1. OPERATION
All the current that flows from the output terminals must
AMPLIFIER also flow through R7. If we now consider the circuitry
Unlike most power supplies, instead of providing voltage around IC3: the inverting input is biased at OV via R21,
control by means of varying the feedback factor in a control whilst the non -inverting input can be adjusted to any voltage
system, this design uses what is in effect a "uni-phase between 0 and 2V. Say it is set at 1V and the output voltage
power amplifier" arrangement. at several volts. If the load is increased the voltage output
The reference section provides 2 x 5.6 = 11.2V, and we will be held at a constant value by the voltage amplifier sec-
require 30V out, hence the gain of the amplifier is 30/11.2. tion and the presence of R7 will have a negligible effect due

1070 Practical Electronics October 1978

to its low value and because it is situated outside the feed- INSTANT "SHUT -DOWN"
back loop of the voltage control circuitry. In order to prevent any spurious effects that may occur as
It is interesting to note that if the load is constant (a the negative rail voltage decays away when power is
resistor for example) and the voltage output is constant, then removed from the unit, transistor TR 1 removes drive to the
the current through R7 is constant and substantially output4s-tage as soon as the rail collapses.
independent of any ripple in the incoming supply. Under normal operation TR1 is held off by R14, but when
If the load is now increased to cause the voltage across the negative rail fades TR 1 comes on and holds the output of
R7 to reach 1V, IC3 comes into action. IC2 low. This does no damage to the i.c. as the 741 has
comprehensive internal output current limit circuitry built
COUPLING into it which limits its output current to a safe 1 5-20mA.
The output of IC3 is coupled to the non -inverting input of The fact that the output from the p.s.u. disappears
IC2 (essentially the input to the voltage amplifier arrange- virtually instantaneously can be an asset when doing test or
ment) with a diode. Thus the current control can "cut in" and experimental work. It allows one to kill the supply and
override the voltage control, but at all other times is totally perform circuit modifications without having to wait first for
disconnected from it. Hence, when in our example the the power supply's internal capacitor to slowly discharge.
voltage across the sensing resistor reaches the predeter-
mined 1V, IC3 adjusts the input to IC2 in such a fashion as CONSTRUCTION
to maintain this voltage across the resistor and thereby form Construction should commence with the etching of the
a second dominant control system-except this time con- p.c.b. and then assembling components onto this as shown
trolling output current and not voltage. in Figs. 2 and 3. As this layout has been proven, it is wise to
C8 provides compensation in this loop to maintain stick to it as much as possible to ensure stability. The
stability. remaining peripheral components should then be connected.

r
TR2 TR 3
2N3053 2 N 3055
D8
5V6 C5 018
220n F Mel 56 k G
T1
VR2 D1C. R16
100k f1 1 kfl
,N4148 +VE OUT
R1 CURRENT)
10
O
01-4 2 2kG 14
18, kP VR3
IC1
3 74 VOLTAGE 7 R15 2-2 fl
C, 1011
1C2 1N4001i
O BRIDGE 4700 R9 74
OF R5 2
012
22k G D11
1000 56 kit

VR I
RR
-#V0-4 4. 7oF
1040 C6 330p F
27
011 47p0 R21
R6 10k Cl
04 C4
-VE OUT 10k11
10 kfl 33 kfl
4 700 101 nE

TR1 R7 817* D12

11, 11,4140 BC 1024 0 311 See text ) TIL 209
2W
02 C2 D5

vim_
1000
I -
1004E
N
IN.
c3
R14
An \if;
1.5 kfl
D6 H3
Fig. 1. Circuit diagram
1N 41.:8 2210 Thick lines indicate direct wiring to maintain stability J

SUPPLY CURRENT TESTING

There is a small amount of current which flows through When building p.s.u.s, power amps. etc. initial switch -on
R7 which does not go to the load. This constitutes the can be a little nerve racking, as small mistakes can easily
negative supply current to ICI and the Zener current. This is result in drastic burn -ups. Ideally a Variac should be used
the reason for R17. It allows voltage appearing across R7 here, as then the input current to the system can be watched
due to this current, and also any due to remanent resistance whilst the input voltage is slowly increased. If it is seen that
in VR3 (when fully anti -clockwise) to be offset. Normally it the current has risen beyond a reasonable value then the
should lie in the range 0-10012 (typically about 33(1). circuit can be checked and the replacement of burnt, charred
components is happily avoided.
NEGATIVE RAIL GENERATOR However, in the absence of a Variac a low value resistor
The circuitry around C2 and C3 forms the negative rail (20-500) of a Watt or so rating can be used in series with
generator. This is required to enable IC2 to control the the secondary of T1, together with a multimeter set to 1A
output voltage down to zero. Similarly since IC3 has to a.c.
control the input of IC2 down to zero, it too requires a When power is applied the meter should just give an
negative supply. IC1 is operating under fixed conditions, initial kick and then settle down to a low value (10-30mA).
however, and therefore can be run between the positive A fault condition exists if the resistor overheats and/or the
unregulated input and earth. current is substantially higher than the above readings.
The negative generator is simply a pump system with Assuming the first switch on has been successfully
simple stabilisation on its output (R3 and D7). accomplished and the unit is drawing the correct current,

1071
Practical Electronics October 1978
 short out the series resistor and make sure the current is still CURRENT LIMIT
around 30mA. Once the voltage system is known to be satisfactory the
Now check that the output of IC1 is between 11V and current limit system can be checked. Diode D9 connects the
12V with respect to the negative output terminal. Check that output of IC3 to the non -inverting input of IC2 and it is
pin 3 of IC2 varies in voltage with the position of VR1, and worth noting that if IC3 output is staying low for some
that when VR1 is fully anticlockwise there is in fact zero reason this will override VR2. If it is suspected that there is a
volts at this point. fault in the current limit system, D3 can be removed and the
Next check that the negative supply pins of IC2 and IC3 two systems isolated. It should of course be replaced before
are at between -5V and -6V with respect to the negative the current limit system is examined.
output. After this check the output of the supply can be To check the current limit system, first make sure that pin
varied from zero to 30V. With VR1 fully anit-clockwise 3 of IC3 varies from OV to about 2V when VR3 is adjusted.
adjust VR2 to trim out any remaining millivolts. Turn VR3 to a minimum. If D12 lights it means R17 is too

c-\ c-0-2 -e t fo-1-01

Fig. 2. P.c.b.

TO TR3
+VE Cl r4-7- 1
GN

G3

Fig. 3. Component layout. If bridge rectifier used R1 can be connected directly to C1

1072
Practical Electronics October 1978
low. Ensure first though that it is not a fault condition.
Now turn VR 1 to give zero output voltage (check this with
a multimeter). Set the multimeter to about 100mA d.c. and
slowly turn up the output voltage with VR1. If all is well, COMPONENTS . . .
D12 should light and the current should limit at a low value
(2-5mA). If this does not happen check D9 and IC3 and Resistors
associated circuitry, with the usual attention being payed to R1 2.2k111W
such things as dry joints and solder splashes. R2 10011
When this stage has been reached a value can be given to R3 22011
R17 if D12 still comes on at VR3 minimum setting. As men- R4 4.7kf2
tioned above it should allow current control down to 3-5mA. R5 101(11
86 10kfl
R7 0.3112W
METERING R8 27k11
A meter is a very useful feature to have on a power sup- R9 2.21d2
ply. It is possible to do without one by having calibrated R10 330k0
voltage and current controls but this does restrict the unit R11 331(12
somewhat. R12 561d/
A circuit which allows switchable current/voltage R13 10k0
monitoring is given in Fig. 4. Current is measured by R14 1 .51(12

monitoring the voltage across R7. This means the unit's very R15 1k11
R16 1kfl
low output impedance is preserved. R17 0-10011 (3311 typ. see text)
R18 56k11
-11 R19 .2.2k11
S2 R20 10k11
1+cnni 0 0
R21 101d2
R22 4.7k12
All 4-W carbon except where otherwise stated

Potentiometers
VR1 3 good quality 10kfl log.
VR2 1001d/ miniature carbon preset

Capacitors
Cl 4,700µF 40V
C2 100µF 40V elect.
C3 100µF 40V elect.
Fig. 4 Monitoring circuit C4 100nF polyester
C5 220nF 63V plastic or ceramic
R and Ry are determined by the meter sensitivity and C6 47pF plastic or ceramic
resistance. If the meter sensitivity is ImA for f.s.d. and it has C7 4.7µF 35V tantalum (or elect.)
C8 330pF plastic or ceramic
a resistance of R P, then R, will be obtained from:
R= 3-9-1 x 1000 - R,y/
Semiconductors
IC1-3 741 (any manufacturer as long as good quality,
Similarly Ry is obtained from: esp. for IC2)
Ry =
1
x 1000 - TR1 BC182L
412 TR2 2N3053
TR3 2N3055
If two meters are available, of course, both voltage and TR4 BC157
current can be monitored simultaneously and S1 can be D1-4 Any 3A 50V bridge (or 4 discrete 3A diodes) e.g.
done away with. RS type 261-457
D5-6 1N4148, 1N914
D7-8 BZY88-5V6
HEATSINKING D9-10 1N4148, 1N914
Any linear power supply with a reasonable output should
D11 1N4001
be equipped with generous heatsinks, and this is no excep- D12 Any suitable Le.d. (TIL 209 etc.)
tion. The worst -case condition for these "linear" type sup-
plies is when they are supplying a high current at a low
voltage. The dissipation in the series pass transistor can Miscellaneous
reach as high as 50W in this case and to keep the junction Mains transformer 240V primary, 20 to 25V, 2A secon-
temperature of the series transistor down to a safe value a dary. Heatsink for TR3, approx. deg. C per Watt (plus
1

heatsink of around one degree C per Watt or better should mica insulation kit) RS type 401-807
be used. Box to suit, on -off switch etc.
The constructor's discretion can be resorted to here: if it is Meter (if required) see text
apparent that the unit is severely overheating and the tran- Switch (Si) if required (d.p.d.t.) + R & Ry values (see
text)
sistor TR3 far too hot to touch (don't get misled however,
they can take junction temperatures in excess of 150
degrees C) then greater heatsinking should be employed. *
1073
Practical Electronics October 1978
 *
fra
"'

MPUTIER P. J. KRONIS B.Sc PART 2

HAVING formed a general picture of the workings of the with the pot slider taken to the negative supply rail. The non -
I I analogue computer, the complete circuit of a computing inverting input of the op -amp is grounded via R8. The value
element can now be described. This is shown in Fig. 2.1. The of this resistor should be chosen for good thermal drift
basic circuits of input and feedback, components connected performance. The optimum resistance would be equal to the
around the op -amp can be readily recognised. The input parallel value of the input and feedback resistances. Since in
comprises four resistors, R, to R4, which are connected to this case there are two values of input resistances, a
sockets in the patch panel and to the inverting input of the compromise solution is necessary.
op -amp, via switches RLA2, S1c, and S1b. The feedback The circuit of Fig. 2.1 represents just one computing
circuit consists of R5, C1 and C2, which can be selected by element and analogue computers may have many such
means of switch S1a and sockets (C7, B6 and C6) on the elements. The prototype has ten computing amplifiers which
patch panel. is an adequate number for the solution of fairly complex
Consider switch S1a set so that R5 is selected in the problems.
feedback loop. The computing element now becomes a
summer. By recalling the equation for the addition circuit R7 R6
that was described last month and by substituting the values B2 )
for R5, Al, R2, R3, and R4 it can be seen that a voltage 100k11 1 100kfl

applied at inputs and 2 will be multiplied by unity,

1 R

( R5 1
RL B2 I son
R1 or R2) 1 Std
2 2

whereas inputs 3 and 4 will multiply an input voltage by 10. Cl

ci
R5 1
10.
k R3 or R4)- 0.1- RI 1NF
C2
C2
I Mil Sic
With capacitor C1 selected in the feedback loop, the C6

R2 *15V
computing element is converted to an integrator and if C3 C 83
values are substituted in the equation for the integrator, it
can again be shown that inputs 1, 2 and 3, 4 give a gain of 1 RLA2

and 10 respectively. The selection of C2 in the feedback loop CA

R3 2
increases the gain of all inputs by a factor of 10. This is 100 kit RI
usually referred to as a nose gain of 10. The symbols used to R
(Sib 27121KB

denote adders and integrators with the relevant gain values CS

ISV
are shown in Fig. 2.2. tookn V
The "Initial Condition" resistors R6 and R7 are brought TO IC14 111C13
into the circuit by means of switches RLA2 and S1 d. VR1 is PINS 3

a 10k12 potentiometer, which provides the op -amp with Fig. 2.1. Circuit diagram showing one of the ten com-
external offset nulling. This is connected across pins 1 and 5, puting elements of the Analogue Computer

1074
Practical Electronics October 1978
 which means that either or both voltages can be positive or
negative. This dispenses with the need to have an absolute
value circuit preceding the multiplier, as is the case with
other methods.
The particular device chosen for the prototype was the
AD533JD integrated circuit (shown in Fig. 2.3). This is not
the cheapest four -quadrant multiplier on the market, but it
has the advantage of being simple to operate, with the
Fig. 2.2. Symbols used to denote adders and minimum of external components. The i.c. comprises a
integrators transconductance multiplying element, a stable reference,
and an output operational amplifier on a single monolithic
Mode Control is achieved by means of relay contacts silicon chip.
RLA2 and RLB2. Relays are necessary because all ten X
amplifiers need to be controlled simultaneously. Table 1
The AD533JD multiplies with a transfer function of 10'
shows the positions of relay and other switches for mode The division by 10 should not worry the programmer but it
control of summers and integrators. should always be borne in mind when solving a problem. The
SUMMER INTEGRATOR op -amp output provides +10V at 5mA, and is fully protected
SWITCH COMPUTE HOLD RESET COMPUTE HOLD RESET against short circuits to ground or either supply voltage. The
RLA2 2 2 1 2 2
inputs are fully protected against overvoltage transients.
RLB2 1 I 2 1 I 2

Sic OPEN CLOSED The Overload Warning Circuit

Sib OPEN CLOSED The operation of the overload warning circuit is very
S1c CLOSED OPEN simple. The output of every computing amplifier is sampled
Std 1 1 1 2 2 2 and compared with a positive and a negative reference
voltage. If the amplifier output goes higher than the positive
TABLE 1 reference voltage, an I.e.d. is switched on, to indicate that
Fig. 2.5 shows how the ten computing amplifiers are the amplifier is saturating in the positive sense. Similarly, if
arranged on a printed circuit board with the component the amplifier output falls below the negative reference
overlay shown in Fig. 2.7. At the extreme ends of the board voltage another I.e.d. is switched on to indicate saturation in
the two four -quadrant multiplier i.c.s are accommodated. the negative sense. The prototype uses +11V as the
This main p.c.b. is connected to other points in the computer reference voltages. An overload warning circuit is shown in
by means of edge connectors. Fig. 2.4. Only one pair of comparators and I.e.d.s are shown
but ten pairs are necessary to serve the ten computing
The Four -Quadrant Multipliers amplifiers. This circuit is arranged on a separate p.c.b. shown
So far it has been shown how to multiply a variable in Fig. 2.6 with the component overlay shown in Fig. 2.8.
voltage by a constant. This is easily done, using the
+155
coefficient multiplier, in conjunction with the amplifier gain. Vin FRON ICI (PIN 61
The formation of the product of two variables is much more
TO PIN 2 1C15
difficult to obtain. Of the many methods that have been
devised, most have involved the use of devices with certain
characteristics, e.g. a diode function generator can be set up
to provide a square law action, or a log-antilog action. Op -
amps are usually employed with these circuits.
For the sake of simplicity and compactness it was decided
to use two four -quadrant multiplier i.c.s in the prototype. As
their name implies these can multiply in four quadrants,

VR2
22 kfl

-15V +15V -15V

-155

Fig. 2.4. Circuit diagram of the Overload Warning

system required for each computing element
Resistor R9 and potentiometers VR11 and VR12 are
PATCH connected across the positive and negative supply rails to
PANEL IC11 form a potential divider that generates the positive and
AD533JD
PATCH PANEL negative reference voltages of +11V and -11V. These
VR I
Ai, .A5
voltages are applied to the inverting inputs of the twenty
7611
comparators as shown. The output of each computing
R9
amplifier is applied to the non -inverting inputs of the
7 5 611 corresponding pair of comparators. The comparators drive
the warning I.e.d.s, the brightness of which is set by preset
potentiometers. The 741 op -amp was also used here as a
comparator. Experience with the prototype has shown that
Fig. 2.3. Circuit diagram of the Four Quadrant the 741 is capable of driving the I.e.d.s with reasonable
Multiplier brightness without overheating.

1075
Practical Electronics October 1978
 110 100 100 1Q0 100

Fig. 2.5. Main p.c.b. containing the ten computing elements and the two Fo

o0e40000 eb 0 00 0 0009 0000c;) spAg'aragcfa

lir (V air sago oir lir oir sir oile oils lip oilo oir olio oar

Fig. 2.6. The Overload Warning p.c.b.

rtiyi 11.1 [1111

'0 TIT TIT TIT IVILIj -In TIT TI TIT TI TIT

- es 1M a TM itrl
III I.11. wir T rlIFITI 111.1

III I ND MI

Fig. 2.7. Component layout for the main p.c.b.

1076 Practical Electronics October 1978

rirm
000 PC

11 4, r2
;

uadrant Multipliers

0 0

lii1;4 16666
Fig. 2.9. P.c.b. design for the Relay
Board
Fig. 2.8. Component layout for the Overload Warning Circuit

1077
Practical Electronics October 1978
 L
COMPUTE
RESET

t
2 I.j
un ft
Fig. 2.11. Coil diagram for relays
The p.c.b. which accommodates the four relays is shown in
Fig. 2.9. Connections to and from this board are also made
The Relay Mode Control P.C.B. via edge connectors.
With ten amplifiers and two relay contacts per amplifier
there is a need for twenty relay contacts. Complete mode Case Construction
control could be achieved with two ten -pole relays, one The front panel requires a large surface area to
operating the R LA and C switches and the other the R LB and accommodate the patch panel, potentiometers, switches,
D switches. Ten -pole relays are difficult to find however and I.e.d.s etc. Because of this it will be difficult to obtain the
the prototype uses four six -pole relays operating in pairs. right shaped case off the shelf. The prototype case was
(The coil connections for the four relays are shown in Fig. constructed from aluminium sheet. Two square panels form
2.11.) This arrangement leaves four unused poles, which the front and the back of the case and the sides, top and
may become useful if it is decided to extend the computer. bottom are cut and shaped as shown in Fig. 2.10, using the
150

100
2 HOLES 0 35
35

1
LS L
_*
126

- -
381

-(I) - -+33+
220
20 HOLES 95
411700410,,Oreenek 1:

146 HOLES 00 ON 12
HORIZONTAL ME VERTICAL
-----.4)::::43,:rtkin..43
$ $ $ * eltILIVED(1)41). -7
300

PITCH eieeeee oe eeeeee

ee ooseeeeeeeeeeeoeeee
k_
e eveeeeeeeeeoeoeeee
eeeeeeeeoeeeeeeeeeoe
F- ***** /4*.+++++. 2 HOLES 0 6

20 SLOTS 10 x 5 13 4 0.- -0 0 0- 0 0- 0- 4 4
20 HOLES 05
4
* * -0-
4 44 44$40- *
4 * -4 I

DIMENSIONS IN mm
2.1

Fig. 2.10. Case cutting and drilling details

1078
Practical Electronics October 1978
same gauge aluminium sheet. A bench vice, folding bar, and For the four -quadrant multipliers four sockets are needed
a sheet metal mallet are useful for this purpose. Fig. 2.10 per multiplier and these are positioned on the extreme left
shows the positions and dimensions of the holes required in and right of the patch panel.
the front panel. A lot of patience is required for the process
of drilling, due to the large number of holes and the fact that
a badly positioned hole will be detrimental to the
appearance of the layout. This is particularly true in the case COMPONENTS . . .
of the patch panel holes. A pitch of 12mm in both directions
is enough to give a reasonable tolerance for positioning Resistors
errors and at the same time avoid excessive gaps between R1, R2, R5 IMO -1-0/ 2% metal oxide (30 off)
the sockets. For the larger holes the use of sheet metal R3, R4 100kf1 PN 2% metal oxide (20 off)
punches is recommended. Having drilled or punched all the R8 270k0 +W 5% carbon (10 off)
holes, the front panel should then be labelled using dry letter R9 1001(11 -ON 5% carbon
transfers and sprayed with a clear lacquer fixative. The R10 7.5kn -WV 5% carbon (2 off)
suggested labelling is shown in the photograph of the front
panel. Potentiometers
VR1, VR8 4.7ki2 (2 off)
VR2-VR7 22161 (6 off)
VR9-VR30 22k0 (22 off)
VR31-VR40 10kf/ 0.5W Lin (10 off)
All horizontal min. presets except where stated

Capacitors
Cl 11.LF 160V(10 off)
C2 0.1µF 160V(10 off)

Semiconductors
ICI -1C30 741 op amp (30 off)
IC31-1C32 AD533JD (2 off)
D1 -D20 TIL 209 (20 off)

1.1 iI I i tni Miscellaneous

4 off 6 way changeover relays
) ) 0 0 C.1 0 0 4 off mounting sockets for relays
holders for i.c.s (if req.)
ri
CONSTRUCTOR'S NOTE: The AD533JD
Four Quadrant Multiplier is available from
Analog Devices Ltd., Central Avenue, East
The Patch Panel Molesey, Surrey.
The patch panel is constructed using 3.2mm sockets
arranged in a matrix and packed together as closely as
possible. There are 148 of these sockets and because
identifying each one is difficult a colour coding system was Stage by Stage Construction
used. Fig. 2.12 shows the arrangement of the sockets for The computer has been designed so that it can be built in
one amplifier, one coefficient multiplier and one four - stages. At this point in the construction, ie, with the
quadrant multiplier. aluminium case and the p.c.b.s constructed and drilled, the
The pattern for the amplifier and coefficient multiplier constructor has to take a decision, as to whether he wants to
shown in Fig. 2.12 is repeated ten times for the ten opt for a stage construction. His choice can be very flexible.
computing elements. The eight coefficient multipliers use 16 For example, one may decide that initially, all ten computing
sockets on the top row. Two of the remaining four sockets amplifiers are not absolutely necessary for the solution of
are connected to the two panel meters and the other two are simple problems with which the inexperienced programmer
connected to batteries to provide reference voltages. Both will be involved. Four amplifiers are enough to carry out
positive and negative reference voltages will be needed for fairly interesting experiments. Later, when more experience
the solution of certain problems. is gained, more computing amplifiers can be added as
necessary. The same applies to the coefficient multipliers
and the panel meters.
Go RO It should be mentioned that if four 6 -pole relays are used
for the mode control, as is the case with the prototype, at
wo 0
YO G - GREEN least two of these will be necessary even if only one or two
0 W R0
R - RED amplifiers are used initially. Two 6 -pole relays can provide
p0 Ro
W - WHITE mode control for six amplifiers.
YO Y - YELLOW
Another area in which stage by stage construction can be
- BLACK
RO YO RO
B
applied, concerns the overload warning circuit. Here, the
BO GO
comparators and the I.e.d.s can be added following the
addition of more amplifiers. Alternatively it may be decided
Ro YO to leave the warning circuit out altogether initially. This will
make life difficult for the programmer, but it will not affect
Fig. 2.12. Patch panel layout for one computing ele-
ment (rows B and C) and one Four Quadrant Multiplier the operation of the computer.
(row A) NEXT MONTH: WIRING AND TESTING

1079
Practical Electronics October 1978
 A selection of readers'
original circuit ideas. It
should be emphasised
that these designs have
not been proven by us.
They will at any rate
stimulate further thought.
Why not submit your
idea'? Any idea published
will be awarded payment
according to its merits.
Articles submitted for
publication should con-
form to the usual prac-
tices of this journal, e.g.
with regard to abbrevia-
tions and circuit symbols.
Diagrams should be on
separate sheets, not in-
serted in the text.
Each idea submitted
must be accompanied by
a declaration to the effect
that it is the original work
of the undersigned, and
that it has not been
accepted for publication
elsewhere.

CAPACITOR CONTINUITY TESTER

THE capacitor continuity tester is built Rather than leave the two unused gates
around a 4011 i.c. using the basic idle, another oscillator was constructed
oscillator circuit shown in Fig. 1. The and this formed the continuity tester, Fig. Capacitor Range Resistor
frequency is approximately, f- 3. The two testers were combined as
1.7 RC Hz shown in Fig. 4. The output was fed to the 0- I ,000pF RI 3.3M11
and this relationship was used to determine BC 108/loudspeaker driver and the 1,000pF-0-01µF R2 430k()
the values of R for a given value of C and combined tester was powered by a PP3 0 -01g -0.111F R3 47k(
a nominal frequency of 1kHz. battery. 0.1µF -1µF R4 4.7k0
The working values of R and the
corresponding ranges of C are given in the
table and the actual tester circuit in Fig. 2.
This tester proved to be a very useful
item especially when dealing with ex -
computer type components etc.
10.-100
10µF
R5
R6 -
3.3kil

A. W. Cunningham,
Strathblane,
0 o/P Stirlingshire.

QD°
T PROBES

Fig I

0/P Fig 3

+ VE

r
PROBES
(CAPACITOR LS1
0/P CAPACITOR
UNDER TEST) 811
TESTER Sib
BC108
PROBES
1c

CONTINUITY
TESTER

Fig 2 Fig 4

1080 Practical Electronics October 1978

 SYNTHESISER REPETITIVE WAVEFORM GENERATOR

It
5V
Ica
7490 1

2.1JF
1 1C7 I 1C8 Oct JC16
1

10 I

IC10
7491

12

Icn
7491

c5b 1 Rt
4.71(11 5V

1C12
7491

1060 1

RS 1

4.7151 SV

I
'Cl)
7491

C60 1 R5 7404
1
d1
5V
Voir 7M
5V
7401

00

---11015
_a1 f t5-I !Rol

180

5V

HE circuit shown loads digital output from the shift registers is then replaced by a 4-10 line or 4-16 line
I information into an 8 -bit shift register loaded into a digital -to -analogue converter, decoder, and with due regard to loading of
when SI is in position "B". In this version consisting of IC17 and 18 and associated the outputs could provide totally
the information is supplied from a components. The values assigned to each independent control over the value of each
telephone dial. The dialling contacts data bit can be varied by VR2-5. This data word.
generate a number of pulses which are enables the output to be "scaled" so that There are many more variations which
used to clock a 7490 decade counter. each word of digital information can be could be added to this list. The final
IC2 and 3 provide contact bounce given the required value. The overall version chosen would depend on the
suppression. The length of the output pulse output level is controlled by VR6. application and on the equipment
may have to be varied slightly by adjusting S2 is used to reset the shift registers to available.
the relevant timing components. zero. The device could be expanded to handle
When the dial is released the second set The circuit as shown lends itself readily multiples of 8 words by adding further
of contacts open and this is used to reset to modification. The telephone dial shift registers in series with those already
the counter and advance the shift registers. circuitry could be replaced by any device in circuit.
During the loading of information S3 producing digital information, as long as a B. Hatton,
should be in position A. When the 8 bits of means is provided for advancing the shift Southampton,
information are loaded, Si is set to registers. Hants.
position A and S3 to position B. The shift The 7490 counter could be replaced by
registers are then advanced by the 555 a 7492 or -93, giving a greater range of
astable at a rate dependent on VR1. The output values. The D -A converter could be

Practical Electronics October 1978 1081

 SIMPLE FUZZ

SK 2
22k11
22kfl OUT PUT

22 WI
SKI
INPUT

0 1,uF
TR1 TR2 9V

8C108 BC108

VR MAIN)
°In 100pF 1k11

VR2 IBIAS1 10,uF

113pF
100 k fl

C* R* SEE TEXT

ACCENTING METRONOME
+5V
0

R4
47011 IC11a) Milt)) IC2(a)
111.- 0--
CLK CLK CLK

K
K CL CL
TR2

BC108

C3
100/JF
10V
TR3 TR4 IC3lb)

2N2219 2N2219

R5
1 kfl
C4
R6 100,u F
SIb
1kfl 101/
IC1 SN7473N
I C2 SN7473N SPEAKER _/
IC3 SN7400N 3-8 fl S2

!ACCENT] OV
0

THE circuit shown produces the same ef- binary counter. The multivibrator pulses single beats since a resistor is not included
fect as the Synchronome described in are fed directly to the clock input of IC I a in the emitter of TR4. R7 reduces the
PE March 1976, but at less than half of the and depending on the position of S I a current through the speaker on single
cost. pulse is sent via C4 and R6 to the base of beats. It should be noted that J -K bistables
An astable multivibrator generates TR4, on the second, third or fourth beat trigger on the trailing edge of the clock
pulses variable from approximately 60 to producing duple, triple and quadruple time pulse, therefore IC3a was included so that
200 per minute which are fed to a NAND respectively. the accent was synchronised with the
gate (IC3a) connected as an inverter. C3 For example, consider quadruple time. single beats. S2 is used to switch off the ac-
and R5 converts the output pulses from In every fourth beat, the Q output of IC2a cent when it is not required.
IC3a to spikes which switch TR3 on, goes to logic 1 which resets the counter via
producing a distinct click in the speaker. IC3b. In every third beat from the reset D. A. Seddon,
The accent is produced by three J -K condition an accent pulse is produced and Widnes,
master slave bistables arranged as a 3 bit applied to TR4. This is louder than the Cheshire.

1082 Practical Electronics October 1978

 REFERRING to the circuit diagram,
TRI is a simple variable -gain pream-
plifier. The amount of gain is controlled by
VR1, and this in turn influences the sustain
time produced.
TR2 and its associated components
form the clipping stage which produces the
fuzz effect. The coupling capacitors are
kept small to prevent lower notes from the
guitar overpowering the unit when chords
are played. R3 and VR2 form a potential
divider which provides bias for TR2. For
the clipping stage to operate correctly, it is
necessary for the bias to be set quite
precisely (as described later).
The reason for this can be best un-
derstood by considering the graph. This
shows the variation in the voltage at the
collector of TR2 as VR2 is varied from
zero resistance to 100ka The limiting plifier and adjust VR2 until the note is and 2.2k0 were used to give a sharp,
occurs if the resistance is set between the audible. (The required position is approx- biting tone. A silicon diode can be sub-
points A and B. If an a.c. voltage is then imately half -way). VR2 can then be finely stituted for the 0A81 but with a conse-
applied via C4, then positive half -cycles adjusted so that the note decays without quent loss of sustain time.
will cause the collector voltage to limit at moving off or becoming distorted. Once The unit is very simple, has a very low
about 0.3V, and negative half cycles will set, the unit will only require adjusting oc- movement consumption (0.5mA) and
cause limiting at 0.8V. Between these two casionally, to compensate for falling bat- gives extremely good results, particularly
points, the gain is approximately linear and tery voltage. Even so, it is advisable to when used with the Phasing Unit (PE
so the decay characteristic of the guitar have VR2 accessible from the outside of 'Sound Design') or Treble Booster (PE
note is preserved (after a period of sustain). the cabinet. April 1976).
The simplest method of setting VR2 is The values of C* and R* depend on the D. McCabe,
to connect the unit to a guitar and am- tone required. In the prototype 0.002µF Manchester.

STEREO INDICATOR
B. +125
3300
(ANY COMMON
CATHODE TYPE)

TR2

FM
RLA 4000
BC309

A
TR1
IC1

2N3B19
47k0 I. 7k11
1kR

I kfl
O a8

TR3 ED $a0FD DEC

220kfl
AM BEY51
Ikil
C COMMON
CATHODE

05
ICI CD4001

TO BEACON PIN ON DECODER 01

THE following is a description of an This is connected in place of the AM/FM and G are permanently connected to the
AM/FM Stereo Indicator for use with a switch in the tuner. The voltage at the positive supply line. This should be at no
stereo radio tuner. It is based on a seven collector of TR3 is taken to a NOR gate more than 15V, or else the i.c. will be
segment I.e.d. display. connected as an inverter. A further signal damaged. The supply should be capable of
The segments are so connected that an is taken from the stereo decoder of the supplying both the relay current and
"A" lights up for AM, an "F" for FM, and tuner in place of the stereo beacon which is 60mA for the I.e.d. display. The remaining
an "S" for FM stereo. removed. IC I encodes these two signals circuitry consumes little current.
A touch switch, identical to that which into a form suitable to give the required D. P. Akerman,
appeared April 1975 issue of
in the display. Dagenham,
"Everyday Electronics", actuates a relay. It will be noticed that segments A, F Essex.

Practical Electronics October 1978 1083

 EXTERNAL INPUT UNIT FOR SYNTHESISERS
0 9V
RI

2 2MO
OEM Cl VR1 R9
JK1 100Kfl
7
C2 5

tuF 1MI1
IC1 7
741 01 R8
2
10,u F 47Kfl IC2 7
4 741
IN 914 2 2MI1 1C3 TRIGGER
HOLD 4
R2 3 741 CONTROL
39 KG TIME
10KII 47Kil R7
(LINT
SIGNAL
OUTPUT 220 KG

;
SIGNAL] VR2
LEVEL mom 03
1090 47,LIF
(LIN) R3 4 910
1 SKR 24K0 47Kf1

0 OV

4Z. 0 9V

nHE unit shown will al ow external in- the input frequency but is not too large as Many interesting effects can be obtained
puts such as guitars, microphones etc. to impair performance if two notes are using an electric guitar with the unit from
to be processed by the circuits within the played very quickly one after another. envelope reshaping to triggered "Wah"
synthesiser. Thus with no input signal the output of and triggered "Phase" if the synthesiser
IC 1 is an amplifier and VR 1 should be IC3 will be sitting at positive saturation has a voltage controlled phaser. Also white
adjusted to give 2V r.m.s. at A with the but when an input signal is applied the out- noise can be triggered and mixed to create
output of the input source at maximum put of IC3 will go to negative saturation strange rushing soutlds with each note
amplitude. This will give about 400rnV for a length of time determined by the played.
r.m.s. at the "signal output" which is ade- duration of the input signal and the setting The unit should work well with both the
quate enough for most synthesisers. of VR3 and will then go back into positive P.E. Sound Synthesiser and the Minisonic
IC1 also feeds a comparator IC2 whose saturation. 1 and IL
reference level is variable and thus the If a synthesiser system is being used P. G. Ludgate,
length of time between the first and last where a positive going trigger voltage is re- Wycombe Marsh,
positive pulses that will appear at the out- quired for the envelope shapers the follow- Bucks.
put is variable due to the nature of sound ing changes should be made: R4 and R7 to
envelopes. +9V instead of -9V. R9 to -9V instead of
IC2 feeds another comparator IC3. The +9V and DI should be reversed. If the
components D1, R7 and C3 make sure trigger output is to go from OV to -8V or
1C3 receives constant positive input level from OV to +8V then diodes can be put on
when a signal is inputted into the circuit. the output as required.
The time constant of R7 and C3 is about With a normal electric guitar envelope
100ms which is more than adequate to VR3 can adjust the trigger pulse length
cope with the negative half of each cycle of from about 10ms to about 3s.

discuss and document no fewer than twenty-nine different programs for

BOOK "Games and diversions" and another thirteen "Utility" programs

designed to expand KIM capabilities and aid system testing. After the

OEN programming section come further chapters on "Expanding your

KIM", "Connecting to the world" and "Pot Pourri" which is
collection of useful information and tips.
The book is well written in an easy going style which does not
assume that all readers already sport a degree or two in computer
science and electronics, as do so many other microprocessor books!
a

THE FIRST BOOK OF KIM -1 Despite its low-key approach and its accent on games and diversions
Edited by J. Butterfield, S. Ockers and E. Rehnke though, this book is a mine of valuable knowledge which should prove
both instructive and useful tfo all present or prospective KIM owners
Published in Europe by Human Electron GmbH whether software or hardware orientated.
Available from Memec Ltd., The Firs, Whitchurch, I feel that I can even recommend this book to readers who do not
Nr. Aylesbury, Bucks. actually intend the purchase of a KIM system, but who thirst after this
210 x 145mm. Price f7.50 kind of knowledge for its own sake. All the programs in the book
include a brief description and a full hexadecimal/mnemonic listing so
THIS is a book "Dedicated to the person who has just purchased a that they can be easily understood and/or entered into a KIM system
KIM -1 microprocessor system and doesn't know what to do with when required. Examples of the games programs listed are: Asteroid,
it" and as such, it undoubtedly fills a very large void! The KIM -1 Bandit, Black Jack, Clock, Farmer Brown, Lunar Lander, and Music
system itself is a microprocessor board based on the 6502 chip. It Box. Utilities include: Directory, Hypertape, Relocate, Sort, and Verify
features a hexadecimal keyboard, a cassette interface, a full IK of Tape. Readers with a different microprocessor system should find these
program RAM and a high standard of documentation. (A full review of programs a source of inspiration and may even find it possible to
KIM -1 was published in the Feb '78 issue.) convert some of them to run on a different system, with a little effort.
This new book makes the KIM -1 an even more attractive My last word comes from the Pot Pourri section of the book.
proposition because it takes the beginner by the hand with a chapter Remember: Computers are dumber than humans but smarter than
entitled "A beginner's guide to KIM programming" and then goes on to programmers! R.C.

1084 Practical Electronics October 1978

 0
EASY BUILD SPEAKER DIY KITS
Specially designed by RT.VC for cost
conscious hi-fi enthusiasts, these kits
incorporate two teak -simulate enclosures.
two EMI 13" , 8" (approx.) woofers, two
tweeters and a pair of matching crossovers.
Supplied complete with an easy.to-follow
Opportunity!
(2800 circuit diagram. and crossover components_
STEREO PAIR Input 15 watts rms. 30 watts peak, each unit.
4 p & p E5,50 Cabinet size 20" , 11" * 9k" (approx.).
AUDIO MODULES IN
SPEAKERS AVAILABLE WITHOUT CABINETS.
It's the units which we supply with the enclosures illustrated
Sve 13" lapprocl woofer (EMIT, 2-1' trip [1700 per
BARGAIN PACKS
tweeter, and matching crossover components. stereo pair
Power handling 15 watts rms 30 watts peak 4 p & p 13.40 CURRENT CATALOGUE
PRICE s
BUILT AND READY TO PLAY
SPEAKERS Two models - Duo Ilb, teak veneer, 12 watts AT OVER
rms. 24 watts peak. ler x 13i" x 71- (approx.).
Duo III, 20 watts rms, 40 watts peak. 21 x 13" x 11"apps
PER PACK
Duo alb E17 PpE8R2PNR50 Duo III 152 oPE:p,ffiso
SEE OUR PRICES
EASY TO BUILD WITH SPEAKERS PACK I. 2 x LPI173 lOw RMS output power audio
NOT TO SCALE amp modules. *I LP1182/2 Stereo pre amp for
ceramic and auxiliary input.
OUR PRICE
p+p fl 00 A.
4.95
Recommended set of
ACCESSORIES

RECORD for the 0 -IT man who requires a stereo unit at a budget price,
2 PACK 2 2 x LP1173 lOw. RMS output power audio
amp modules + 1 LP1184/2. Stereo pre amp for
magnetic, ceramic and auxiliary inputs
illUSOUR PRICE
Suitable power supply parts including
mains transformer, rectifier. smoothing
and output capacitors
I
rotary stereo controls
comprising BASS, TREBLE,
VOLUME and BALANCE.

PLAYER comprising ready assembled stereo amp module Garrard

KIT auto/manual deck with cueing device, precut and finished
cabinet work. Output 4 watts per channel, /.4 nr
p+p f 1 00 £7.45 11.00 p+p Pit 50P 95p
phones socket and record/replay socket
including 2 SPHERICAL HIFI speakers

AM/FM STEREO TIMER AMPLIFIER CHASSIS COMPLETE.

L I U.V0
p&p 14 05

Ready built Designed in a slimform for compact, modern installation

3 PACK 3. Iz LPI179/2FMTuningheadwith AM gang, I xLPI 165/1
AM/FM IF module, 2 x 1P1173/10w. RMS output power audio
amp modules + 1 LP1182/2 Stereo pre amp for ceramic
and auxiliary input.

Rotary Controls Vol On/Off, Bass, Treble. Balance

Push Buttons for Gram. Tape VHF, MW. LW and 5 button rotary
selection switch
OUR PRICE
p*p fl 00 f9.95
Power Supply Selenium Bridge -35V DC from 210-250V AC. 50Hz
ulna TRADE ENQUIRIES INVITED
Aerial Ferrite 8" z. 1/4" built into chassis for LW and MW plus flying
lead for FM aerial 45 WATT MONO
Power Output 5 watts per channel Sine at 2% THO into 15 Ohm DISCO AMP
7 watts speech and music
f 350p00
Tape Sensitivity Playback 400mV/30K OHM for max output Record
200mV/50K output available from 25KHz 1150mV/100K1deviation ::: t./ C, 1 cr L- 1 , O r t. 0 Size approx.
FM signal Frequency Renee (Audio) 50Hz to 17 KHz within t. ldB eww............e.,
131- 51" 6j"
Radio FM sensitivity for 3d8 below limiting better than 10 uV
AM sensitivity for 20 dB S/N MW 350 uV/Metre LW ImV/Metre
0 x 20 WATT STEREO AMPLIFIER
Superb Viscount IV unit in teak -finished cabinet.
'29" 45 watts rms. 90 watts peak output. Big features
Site apprise length 16" a height 2),." a depth 41/4" Silver fascia with aluminium rotary controls and include two disc inputs, both for ceramic cartridges. tape
p&p
P&P (250 19.95 pushbuttons, red mains indicator and stereo jack E2.50
input and microphone input. Level mixing controls fitted
with integral push pull swathes Independent bass and
socket. Function switch for mic. magnetic and crystal
treble controls and master volume
VALUE FOR PERSONAL SHOPPERS pick-ups, tape. tuner, and auxiliary Rear panel features two

lErs 18 VOLT MAINS TRANSFORMER. 21/2 may

BSR Record auto deck on plinth with

f2.50
mains outlets. DIN speaker and input sockets. plus fuse.
20 + 20 watts rms, 40 + 40 watts peak.
30 0 30 WATT AMPLIFIER KIT
11° f2
r 70 & 100 WATT
MONO DISCO AMP
Sue amok
-r-
ir- . i
I II 0
For the experienced constructor complete in every
f11.95 14- , 4" , 10-1. ...;. 1 I I

.
stereo cartridge ready weed.
detail. Similar facilities as Viscount IV amplifier. p & p £2.50 Brushed aluminiumm e
LED 5 function men's digital watch vv. 1

60+60 peak. '

stainless steel finish f5.95 AVAILABLE NOW built and fully tested with
fascia and rotary controls.
Five vertical slide controls master volume.
LCD 5 function men's digital watch
output 30 + 30 watts rms. 60 + 60 peak.
stainless steel finish f7.95 SPECIAL OFFER: PACKAGE PRICE WITH 30 x 30 KIT Mk..11
tape level, mic level, deck level, PLUS INTER DECK FADER
for perfect graduated change from record deck No. 1 to
LCD 8 function CHRONOGRAPH men's digital
watch stainless steel finish f12.95 version, operates into 4 to 15 OHMS speakers. Designed by R &TVC
for the experienced constructor. Complete in every detail, facilities
No 2. or vice versa. Pre fade level control 100 waauttpeakE57
STEREO CASSETTE record/replay fully built P.0 (PFL) lets YOU hear next disc before fading
board. Used, without guarantee (Ex Equipment) f1.95 as Viscount IV amplifier 60 + 60 peak. Supplied with 2
Goodmans Compact 12" bass woofer with cropped 14.000 Gauss it in. VU meter monitors output level p & p £4.00
Magnet. 30 watt. rms. handling + Output 100 watts RMS 200 watts peak. 100 watt 155
125 Watt Power Amp Module
f13.95 31-" approx. tweeters and crossovers. £4.00
CHASSIS RECORD GARRARD DECK CC10A f795
Mains power supply parts
f3.50 ADO -ON STEREO CASSETTE TAPE DECK KIT,
Designed for the experienced 0,1,0, man. This
PLAYER DECKS sRteceroeor d ccehr aa mn r cwa rti t rh,

p & p (2.00
100K Muluturn Vatican tuning pots. 6 for
MUSIC CENTRE CABINET with hinged smoke f1.00 kit comprises of a tape transport mechanism BSR MP60 TYPE Single
El 595
acrylic top, finished in natural teak veneers, ready built and tested record 'replay play record deck
size 301/4" x 14',5" x 71/4" approx. f5.95 electronics with twin V.U. meters and less cartridge.
Cartridges to suit above
p & p 12.55
level control for mating with mechanism.
MOLLARD Built power supply
Acts, magnetic stereo £4.95
OECCA DC 1000 Stereo Cassette P C.B f1.50 Specifications: Sensitivity - Mac.
0.85 mV rr 20K OHMS: Din. 40mV 12" x 111" Ceramic stereo E1.95
complete with switch oscillator coils and . 400K OHMS: Output - 300mV RMS per channel 1KHz approx BSR automatic record player deck
rape -heads f2.95 from 2K OHMS source: Cross Talk - 30db Tape Counter - cueing device and stereo ceramic head. p & p (2.55 f 995
IMF RS 80 Monitor loudspeaker cabinet
size amen 43%"a 151/2" x 151/4" f24.95 3 Digit- Resettable : Frequency Response - 40Hz -8KHz ± 6db
Deck Motor 9 Volt DC with electronic speed regulations
BSR MP 60 type, complete with magnetic cartridge. 129
OECCA 20w Stereo speaker kit comprising -

Key Functions Record, Rewind. E1 995 diamond stylus, and de luxe plinth and cover. p & p E4.50
2 8" anorak bass units n 2 31/2" approx.
tweeter inc. crossovers f20.00 Fast Forward. Play, Stop & Eject. p & 0 12.50 Home 8 Track cartridge player This unit will match ,
2 BAND CLOCK -RADIO. Mains operated with Opt extras Mains transformer to suite f2.50 fl p&p with the Viscount IV 9- 8" .-- 31" p p f C150 050
sleep control f10.95 Order by giving
VIDEOMASTEIT Super Score TV Game
f14.95
wits pistol maxis operation
VIDEO MASTER Dow Tunes
124 dinerem titles) f12.95 El El
323 EDGWARE ROAD. LONDON W2
credit card
number ONLY.
PORTABLE DISCO CONSOLE
Hereportable
a the tno-yalue poable disco console
him RT-VC, h features a pelt of BSR MR 60
type auto Mum uncle play of
Micro cassette tape recorder 21D HIGH STREET. ACTON W3 6NG with sums record decks Plus all the controls and fratu7e7""

7" TAPE TRANSPORT Mechanism -a selection

f13.95 ALL PRICES INCLUDE VAT AT 121, yon need to wee I abolous disco
eic,,t.s:nlo your rusting slave or f
of models from f8.95 AK area adagio to svadebility. PAM correct
1.8.78 and subject to change without notice.
0. 01150 64.0 0
A
Personal Shoppers EDGWARE ROAD LONDON W2 Tel: 01-723 8432. 9.30am-5.30pn. Half day Thursday. ACTON: Mail Order only. No callers GOODS NOT DESPATCHED OUTSIDE UK

Practical Electronics October 1978 1085

 C.-MOS T.T.L. D.I.L. SOCKETS LOUDSPEAKERS
ALL PRICES INCLUDE VAT & P/P CATALOGUE 40p 4000 16p 7400 13p 8 pin 10p 16 pin 14p
4001 18p 7401 15p 14 pin 13p 28 pin 30p 72p
MIN ORDER 12.00 4002 18p 7402 16p ,n, SE 72p
4006 110p 17p OPTO 2in 80 72p
THE COMPONENT CENTRE 4007
4008
20p
97p
7403
7404
7405
7406
22p
22p
44p
TIL209
TIL209
TIL209
Red
Yellow
Green
14p
24p
24p
2' in
2-; in
2'in
80
80
640
64p
64p
72p
7 LANGLEY ROAD-WATFORD- HERTS -WD1 3PS 4009
4010
02p
62p 7407 44p 2
2
Red
Yellow
18p
30p
2in

in
80
800
76p
118p
Phone Watford 45335 Callers welcome 9.30-5.30 Mon -Sat. EC. Wed. 4011 19p 7408 22p
23p 2 Green 30p
4012 20p
59p
7409
7410 16p TIL209 Clip 4p TRANSFORMERS
4013
TRANSISTORS DIODES LINEAR I.C's 4014 108p 7411 24p 2 Clip 5p Mains prim 220-240V
AC126 21p BC547 1 MJ2955 9p BY127 lap CA3011 86p 4015 97p 7412 24p N EONS 6-0-6 10ONVA 93p
AC127 21p BC548 144pp MJE340 649p 0A47 9p CA3014 190p 4016 59p 7413 38p Red 9-0-9 75M/A 97p
AC128 21p BC54 1 MJE2955 99p 0A70 9p CA3018 86p 4017 99p 7414 66p Green 34 12-0-12 10ONVA 99p
AC176 21p BC5579 144pp MJE3055 68p 0A79 14p CA3020 174p 4018 99p 7416 33p Amber 39p 0-6-0-6 280M/A 150p
AC187 23p BCY34 74p 0C28 108p 0A81 15p CA3023 186p 4019 65p 7417 33p Neon Bulb 20p 0-12-0-12 15ONVA 150p
AC188 23p BCY70 17p 0C35 108p 0A85 14p CA3028 85p 4020 119p 7420 18p 6-0-6 1.5A 345p
AD149 65p 8CY71 20p 0071 19p 0A91 7p CA3030 120p 4021 99p 7425 28p RESISTORS 280p
AD161 50p BCY72 17p 0084 46p 0A95 9p CA3035 190p 4022 94p 7427 28p 0.3 watt 100 to I MO E24 2p 9-0-9 1A
50p 7430 20p 0.5 watt 100 to 10M0 E24 2}P 9-0-9 2A 398p
ADI62 50p El 0115 59p TIP29 0A200 9p CA3036 115p 4023 21p 12-0-12 1A 317p
AF114 30p BD124 97p TIP30 52p 0A202 9p CA3042 198p 4024 83p 7432 28p 2.5 watt 0.220 to 100 w/w leap
47p 59p 7437 29p 5 watt 4.70 to 10K0 w/w 15-0-15 1A 350p
AFI 15 27p BD131 TIP31 N914 4p CA3045 275p 4025 20p 20-0-20 2A 544p
AF116 25p BD132 47p TI P32 59p N916 6p CA3046 90p 4026 190p 7441 74p 10 watt 100 to 10K0 w/w
43p 107p 7442 74p 25-0-25 2A 585p
AFI17 23p BD135 TI P33 N4001 Bp CA3048 205p 4027 59p 30-0-30 2A 625p
AF118 30p B D136 50p TI P34 60p N4002 Bp CA3049 154p 4028 96p 7445 123p 12V 2A 367p
AF124 32p BD137 50p TIP35 253p N4003 Bp CA3052 152p 4029 118p 7446 123p 1 KO -2M0 S/gang Lin -Log 27p
AF125 32p BD138 51p TIP36 389p N4004 7p CA3054 73p 4030 62p 7447 102p 5K0 -2M0 S/gang Switch Log 55p
7448 5K0 -2M0 D/gang Lin -Log 70p Antes X2 5 watt Iron 385p
AF126 32p BD139 51p TIP41 59 N4005 10p CA3078 136p 4031 249p 130p Antex C2 15 watt Iron 385p
AF139 40p B D140 52p TIP42 59p N4006 10p CA3080 57p 4032 108p 7454 19p
SLIDERS Antex CX 15 watt Iron 385p
AF239 46p 8E173 30p TI P2955 126p N4007 11p CA3081 148p 4033 157p 7470 39p 5K0 -500K0 5/G Lin -Log 73p Antex stand 155p
BC107 9p 8E179 37p TIP3055 64p 3A -50V 18p CA3086 47p 4035 130p 7472 28p Desoldering gun
9p BF180 37p ZTX108 12p 87p 5K0 -500K0 D/G Lin -Log 811p 640p0p
BC108 3A -100V 16p CA3090 329p 4041 7473 39p Presets sub. mm. 1000-5M0 10p Spare nozzle 9
BC109 9p BF181 37p ZTX300 12 3A -200V 18p CA3130E 113p 4042 85p 7474 33p Slider Bezzels 21p PP3 Batt clips 6p
BC147 10p BF182 37p ZTX500 12pp 3A -400V 20p CA3140E 74p 4043 99p 7475 48p 10p PP9 Batt clips 10p
BF183 37p 2N1305 25p 4044 96p Slider knobs
BC148 10p 3A -600V 25p CA3160E 140p 7476 40p Ferric chloride 95p
BC149 10p BF194 13p 2N1306 39p 10A -50V 25p LM301 39p 4045 150p 7480 46p CAPACITORS Etching pen 81p
BC157 11p BF195 13p 2N1711 21p 10A -100V 25 LM308 54p 4046 131p 7482 91p Min ceramic 245p
13p 2N2219 21p Etching kit
BC158 11p BF196 10A -200V 28pp LM380 106p 4047 95p 7483 90p 22 pf to 3300 pf 4p each Telephone pickup coil 70p
BC159 11p 8E197 16p 2N2904 26p 10A -400V 36p LM361 120p 4049 65p 7485 106p 16p
26p SWITCHES Ear piece std.
BC168 12p 8E200 36p 2N2905 10A -600V 42p LM710 41p 4050 65p 7486 36p Ear piece crystal 33p
BC169 BF224 18p 2N2906 20p LM741 24p 4054 120p 7489 399p Large SPST 27p
Speaker cloth, black
BC171 112p BF257 37p 2N2926G 9p BRIDGE LM747 73p 4055 140p 7496 57p Toggle SPDT 29p 36in x 25in 120p
BC172 BF258 40p 2N2926R 9p LM748 38p 4056 140p 7491 82p DPDT 35p
12p BF259 44p 2N2955 99p RECS 73p 4060 117p 7492 57p STD SPST 66p
BC173 IA 50V 22p LM3900
BC177 lop BFR39 30p 2N3053 17p
lA 100V 24p MC1304 292p 4066 70p 7493 57p Toggle SPDT 70p
lap 34p 2N3054 54p DPDT 75p
BCI 78
BC179
8C182L
16p
13p
BFX29
BFX30
BFX84
3Bp
27p
2N3055
2N3702
54p IA 200V
1A 400V
IA 600V
27p
30p
34p
MC1310
MC1458
MC1496
197p
78p
78p
4067
4068
4069
410p
24p
22p
7494
7495
7496
83p
70p
83p
Min
Toggle
SPST
SPDT
54p
58p
COMP. KIT
BC183L 11p BFX85 29p 2N703 1ST 34p NE555 33p 4070 60p 74100 130p DPDT 70p BRANDED NEW DEVICES
31p 2N3704 2A 50V C. off DPDT 90p
BC1841 13p BFX86 2A 100V 36p NE556 76p 4071 22p 74107 36p A pack of useful general pur-
BC212L 13p BFX87 31p 2N3705 38p NE561 385p 4072 23p 74118 125p Sub. min. SPST 48p pose components.
29p 2N3706 2A 200V 52p
BC213L 13p 8 FX1313
2A 400V 40p NE562 385p 4076 167p 74121 38p Toggle SPDT
Resistors 10 off each
BC214L 14p BFY50 17p 2N3708 42p NE565 138p 4077 65p 74122 55p DPDT 60p Value El 2 100-82M0
17p 2N3709 2A 600V Push button SPST 60p
BC238 14p BFY51 1 1,;
NE566 128p 4078 24p 74123 103p Capacitors 100 mixed from
21p 10p 69p
40p 2ATRIALS
BC303 30p BSX20 2N3711 NE567 175p 4081 23p 74144 345p SPOT
100 pf to 10000F
BC328 15p BU105 191p TIS43 100V 26p SN76003 185p 4082 23p 74145 83p DPDT 91p
2N2646
299p 56p 2A 200V Bias push make 15p 5x NPN 5x PNP Gen. purp.
BC338 15p BU208 42p SN76013 185p 4086 24p 74153 62p 10 xIN914 4x4002
2A 400V lIp SN76023 160p 4501 74154 138p
19p Bias push brake 20p 2x741 1x555
S.C.R. THYRISTORS 6A 100V 50p SN76033 259p 4502 130p 74165 115p Slide sub.min. DPDT 13p
3 xsockets L.E.D's
59p 10A/400V 70p 6A 200V 66p TAA621 257p 4507 59p 74174 132p Slide std. DPDT 13p
1A/50V 28p 5A/400V Slide C. off 15p Switches Batt. clips
1A/200V 38p 5A/600V 75p 10A/600V 83p 6A 400V 81p TAA661 175p 4510 132p 74175 79p DPDT
Audio TRX Tuning cap
1A/400V 40p 5A/800V 82p 10A/800V 129p 10A 100V 68p T8A540 236p 4516 132p 74180 85p Relays
1A/600V 58p 7A/100V 59p 16A/100V 83p 10A 200V 100p T8A641 281p 4518 114p 74181 295p ROTARY (Adjustable stop) Etc.
EXCELLENT VALUE
3A/100V 36p 7A/200V 68p 16A/200V 67p 10A 400V 113p TBA800 102p 4519 60p 74192 131p 1 P/2-12 way 2P/2-6 way
3A/200V 38p 7A/400V 120p 16A/400V 82p 10A 400V Plas. TBA810 113p 4532 138p 74193 131p 3P/2-4 way 4P/2-3 way
3A/400V 51p 74/600V 123p 16A/600V 115p 130p TBA820 90p 4539 119p 74198 185p Price each 46p ONLY £10.95

SEE THE
DIYAM BRING YOU THE NEW CHINAGLIA
DORA CHIME KITS IN THE
NEW DORAM HOBBIES
CATALOGUE.
MINOR POCKET
MULTIMETER
THE
PROFESSIONAL

Baia iLlistrise SOLUTION

TO
GENERAL
MEASUREMENT
Doram Electronics Ltd PROBLEMS
PO Box TR& Leeds LS12 2UF
£32.50 inc. VAT.
Please send my FREE Hobbies Catalogue. I (AVAILABLE LATE SEPT)
The best instrument for the workshop, school, toolbox, T.V. shop and anywhere
I enclose 25p contribution to p. & p. accurate information is needed quickly and simply.
IT OFFERS:
Name * Single -knob range selection
* 110° Full -view mirror scale and fine line pointer
Address * Clear unambiguous scales
* A well -damped cylindrical magnet movement with resilient bearings
* 31 ranges providing coverage from 150mV to 1.5kV d.c.; 7.5V to 1.5kV a.c.;

NM
506A to 2.5A d.c.; 25mA to 12.5A a.c.; 10k0 and 10M0 resistance and six
signal level ranges.
Doram Electronics Ltd * Accuracy *2.5% d.c., ±3% a.c. and 2% resistance.

PO Box TR8, Leeds LS12 2UF For details of this and other exciting Alcon instruments please write or phone:-

Overseas customers (except for N. Ireland) -60p

including dispatch by Air (or all -up post).
alteernstruments Ltd.
19 MULBERRY WALK. LONDON SW3 6DZ TEL: 01-352 1897
0.11.1.11essone.

1066 Practical Electronics October 1978

 Data has to be protected from unauthorised access and theft.
Installations need to be protected from damage. Efficient measures are

(News Oriels)
needed to ensure the smooth running of an organisation and to preserve
competition. The type of information held may be subject to control.
The effects of information systems on organisational structures and the
consequent wider social implications will be significant.
Each issue of the journal will deal with a selection of the above topics
and will contain five or six papers, industry news and international
by Mike Abbott reviews of working groups, legislation and practice, conference reports,
book reviews, calendar and literature reviews.
STRAIN GAUGE Topics covered will include: Techniques; Legislation; Information
it is certainly nice to know if a bridge is likely to collapse due to Systems; Working Group Activities; Case Studies; Computer Crime
I fatigue, or any other structure come to that! The most common
Casebook; Organisational Aspects; Current Interest Section.
method of analysing stress distribution and resultant strain is to employ Readership wilL,be international and aimed at: Computer Engineers
strain gauges, and the photograph shows the latest from Hottinger and Designers; Systems Analysts and Programmers; Data Processing
Baldwin and Messtechnik (HBM for short), the LY41. The wires Managers; Management services and top management; Legal Advisers;
soldered to these gauges give an indication of their size, and this new Beneficial users; All professionals who deal with computer based
range of low cost strain gauges have a unique integration of etched foil information systems.
and tinned soldering terminals fully embedded in a 401.im thick Further details can be obtained from G. W. Jones, IPC Science and
polymide carrier, specifically designed for ease of application in the Technology Press Ltd., IPC House, 32 High Street, Guildford, Surrey
field of static and dynamic stress analysis. GUI 3EW.

MICRO POWER PACK

DESIGNED especially for Series/80 microprocessor -boards but
applicable to other microprocessor systems, is a new multi -level
power supply from the Computer Products Group of National
Semiconductor, which combines precise line and load regulation with
current limiting, over -voltage protection and power -failure detection.
The BLC 635 power supply provides +12V at 2.0A, +5V at 14.0A,
-5V at 0.9A and -12V at 0.8A. Incorporated are circuits to limit
current at 1.2 times rated values at all levels, and over -voltage circuits
which trip at 1.16 to 1.32 times rated voltage.
Load regulation is 0.1 per cent for a 50 per cent load change and line
regulation is 0.1 per cent for a 10 per cent variation. Ripple is 10mV
peak -to -peak, from d.c. to 500kHz, on all outputs. Stability is 0.05 per
cent for 8 hours with constant line, load and temperature. Remote sens-
ing is provided for the +5V level and all outputs may be trimmed+5 per
cent from nominal values.
An a.c. power failure detection circuit supplies a TTL compatible
They combine good continuous vibration response, low hysteresis, high-level signal when line voltage drops 10 per cent below normal. The
excellent linearity and wide temperature range with a flexibility that signal returns low when line voltage reaches 8 per cent of normal value.
allows the gauge to be bonded to a 0.3mm radius surface. Each of the For orderly shut -downs, all d.c. levels remain within specification for
types (LY41 with a temperature co -efficient that matches steel and 2ms after low line conditions and 7.5ms after complete power loss.
LY43 that matches aluminium), are available in 9 different sizes in 120 The line transformer is tapped for 100V, 115V, 200V and 230V a.c.
ohm and 350 ohm nominal resistances. The 100/115V and 200/300V lines are separately fused. Input fre-
quency is 47Hz to 63Hz. The BLC635 measures 81 x 161 x 320mm
and *eighs 5 -9kg (13Ibs.).
BIG BROTHER CHECK
BEFORE it goes too far .Before what goes too far? Well, every
.

organisation you deal with is, or will eventually have your details
held by a computer. Banks, building societies, the taxman, your COMPUTERS GALORE CLUB
employer, vehicle licensing, police records, local authorities, hire
purchase and finance companies, insurance companies . . . "all right,
that's enough" I can hear you say. It is enough (or should be), but it will
- HE NORTH London Hobby Computer Club will be opening on Wed-
nesday, October 5. The Department of Electronic and Com-
munications Engineering of the Polytechnic of North London will be
probably get worse. How? When these machines start conferring with making available much of their equipment for the club. They have two
each other. When judgements are made concerning your welfare, based PETs, (third coming soon), four 6800 based computer systems, floppy
on facts or past events, perhaps even forgotten by yourself, and through disc, printers, VDUs, and some KIM and Motorola microcomputer
which doors are closed to you by nondescripts with your life history systems. Can't be bad if you live in the area and are looking for some
and status at their fingertips. "hands on" experience, because the club is open to all, not just the
If this prospect frightens you (and it should do), you will be students.
interested to learn of a new bimonthly journal from IPC Science and It is hoped that a few "home -brewed" activities get going before
Technology Press, called "Information Privacy", and which sprung to Christmas, and some meetings are expected to be centred around talks
life, guns at the ready, this September. by manufacturers and discussions on programming. However, from the
"Information Privacy" is an international journal which will cover new year it is anticipated that three sets of activities will run con-
the technical, legal and social issues of computer -based information currently (or sequentially depending upon membership numbers), and
systems and their use. Hardware, software and security considerations these are: short courses on programming in Basic, and at machine level,
will be covered in detail as will the needs for and application of legal a home-brew section using the department facilities (up to 35 people
controls, codes of conduct and practice and social implications. The can solder and test at the same time), and introductory talks and discus-
value and use of data information systems to individuals, organisations sions for those intending to run their own systems.
and the community will be important areas of discussion. The club is being organised by members of the Amateur Computer
System analysts, designers, data processing managers and beneficial Club, as well as lecturers in digital electronics. If you are interested, hop
users now have to consider carefully the development and use of on the Piccadilly Line to Holloway Road Station, and you'll find it all
databases and databanks. Transnational dataflow poses worldwide happening in Room 47 of the old polytechnic building opposite the tube
problems of control. station. The inaugural meeting starts at 6.30 p.m.

Practical Electronics October 1978 1087

 RANGE
TIMER
J.D.JARDINE

HE unit to be described here is a two range timer which R2, VR3 and VR4 with respect to its inverting input (pin 2).
I is capable of generating either 0-10 sec or 0-100 sec This causes the output to IC2 to generate a positive going
variable timing periods depending on the range selected. ramp waveform the slope of which is determined by C1, R1,
The construction and calibration of the unit is straight VR3 and VR4. With IC2 acting as a constant current
forward with its output voltage capable of driving either an generator the slope of the ramp is linear.
I.e.d. or small reed relay for the duration of the set time This ramp voltage is applied to pin 2 of the voltage com-
period. parator (ICI) which compares it with a reference voltage set
The timer was originally constructed for photographic use by VR1 and VR2. When the positive voltage on pin 2
where its good repeatability ensured consistent results when reaches a level which is a few millivolts positive of pin 3 the
multiple print processing; but with it being portable and output of IC2 is switched low and the relay de -energised.
reasonably small, it has found many other general purpose TR1, R3 and D4 provide a stable 11.5V supply to the
applications. circuit and D1 eliminates the slight glow in the I.e.d. due to
the saturation voltage of the i.c. when the unit has timed out.
CIRCUIT DESCRIPTION
The complete circuit diagram of the Two Range Timer is CONSTRUCTION
shown in Fig. with the range required being selected by
1 In the prototype the components were soldered onto 0.1
S1. in. Veroboard using the layout shown in Fig. 2. After solder-
If when S1 is in the position shown (0-100 second range) ing, the board and other components were fitted into
and S3 is pressed C1 is discharged and the timing period is 110mm dia. metal case which should be drilled or punched
initiated. After S3 has been released the output voltage of as shown in Fig. 3.
the comparator (ICI) is switched high and the relay The layout of the components inside the case is shown in
energised. the photograph with the push button mounted on the lid.
IC2 which is connected as an integrator has its non - The cursor which is made of Perspex can be curved by
inverting input (pin 3) held positive by the potential divider warming it over a hot soldering iron and gently bending it to

R4
6500

D3
3.3V
400.W

D4
now

L- _
Fig. 1. Complete circuit diagram of the Two Range Timer

1088 Practical Electronics October 1978

 T 0 VR1 rt. TO ON /OFF
RELAY COIL SWITCH +VE

PUSH BUTTON -11

IN LID
4- "-ea p
t_t_9_t 9 99 E
TR1

IC2 7 ICI TO SRI

VR2

Cl R R2 41:$"-\111L414
VR1
SLIDER

TO RANGE SWITCH COMMON

TO RANGE SWITCH FROM VR3 A.11--. \1N -TO RANGE SWITCH FROM VR4
Fig. 3. Case drilling details

Fig. 2. Veroboard layout point of the potentiometers shaft rotation. Alternatively the
scale can be left blank except for the 0 and 10 marks and
shape. The index line should be scribed using a sharp knife calibrated as described in (b) (for more accurate time
and then the small knob should be fixed to the cursor using periods).
an epoxy adhesive.
The scale is thin white card, cut to the size shown and CALIBRATION
marked off with 100 two millimetre divisions and it is moun- (a) Using a pre -marked scale.
ted on the case with its mid -way point opposite the centre (1) Switch on and set the range switch to the 10 second
range.
(2) Set the cursor to 0 and push S3, and relay or I.e.d.
should energise for a short while before dropping out;
VR2 should then be adjusted so that When the button
COMPONENTS . . . is pressed, the relay or I.e.d. is energised for as short a
period as possible (less than 0.1 seconds).
(3) Set the cursor to 10 and press the button; using a
Resistors stop watch or clock, time the period before the relay
R1 1.5M0 or I.e.d. drops out.
R2 2.2k0 (4) Adjust VR4, press the button and re -time; adjust VR4
R3 3.9k12
"R4
again if necessary. Repeat until a 10 second delay is
68052
All -1-W 5% carbon obtained.
(5) Switch to the 100 second range and repeat steps 3
Capacitors and 4 using VR3.
C1 1µF polyester (C280 type) (b) Using an unmarked scale.
Go through items 1, 2, 3, 4, 5 then select an intermediate
Potentiometers time (on either range) and set the cursor somewhere near;
VR1 10ki2 0.25W linear push S3, time it through and thus adjust the cursor closer to
VR2 4.7k0
VR3 1001
the desired point. Repeat until the time period is exact and
VR4 1k0 mark to scale, other times are obtained by the same method.
All horizontal sub -min presets except where stated

Semiconductors
D1 1N4001
D2 12V 400mW Zener
*D3 3.3V 400mW Zener
*D4 TIL 209 I.e.d.
TR1 BC107
IC1, IC2 741 op.amp. (2 off)

Switches
Si, S2 DPDT slide type (2 off)
S3 push to make (latching) switch

Miscellaneous
Reed relay R.S. type 348-986
PP3 battery (2 off)
0-1" matrix Veroboard OTHER RANGES
Clear Perspex The timing range generated by the unit is a function of the
Control knob
value of VR3, VR4, Cl and R 1.
Battery clips (2 off)
110mm dia. case Therefore to double the ranges (0 to 20 seconds 0 to 200
*See Fig. 1. seconds) Cl could simply be doubled in value; although due
to the new components tolerance a small recalibration may
be required.

Practical Electronics October 1978 1089

 STEAM ADVICE

News Briefs' MOST people are by now aware that there are going to be some
changes made in the ether on 23 November this year, when a new
international frequency agreement comes into force. This provides for a
considerable increase in the number, and power of transmitters used in
Europe.
As a result of these new conditions, and to make best use of the fre-
UNDERGROUND CAMERAS quencies available, the BBC is reorganising its arrangements for broad-
casting Radios I, 2, 3, and 4 on the medium- and long -wave bands.
NEVER jump to the conclusion that because you are alone, you are
Radio I will be transmitted on 1053 and 1089kHz (285 and 275
not being watched. We are beginning to take for granted those
metres) MF instead of 1214kHz (247 metres) MF. The low -power
rooftop cameras watching busy junctions and stretches of motorway.
We have reported in this column, remote control cameras monitoring
transmission on 1485kHz (202 metres) MF at Bournemouth will be
retained.
bus queues as part of public transport schemes. You see them at
Radio 2 will be transmitted on 693 and 909kHz (433 and 330 metres)
automatic railway crossings, department stores and public places.
MF instead of 200kHz (1500 metres) LF and 1484kHz (202 metres)
Here is another news brief concerning those ever accumulating eyes.
MF (Scotland).
A closed -circuit -television transmission and switching system is to
Radio 3 will be transmitted on 1215kHz (247 metres) MF instead of
monitor the three stations on London Transport's new Piccadilly Line
64 7k Hz (464 metres) MF.
extension to Heathrow Airport. Designed by British Relay (Electronics)
Radio 4 will be transmitted on 200kHz (1500 metres) LF instead of
to a London Transport specification, the system provides video
692, 908 and 1052kHz (434, 330 and 285 metres) MF. There will be
switching facilities at each of the three stations for local monitoring,
additional transmissions on 603kHz (498 metres) for Tyneside;
and a transmission system to Earls Court (a distance of 13 miles), for
720k Hz (417 metres) for Northern Ireland; 1449kHz (207 metres) for
remote monitoring of the station platforms by the line controller.
Aberdeen; and 1485kHz (202 metres) for Carlisle.
It has been provided as an operational aid to control passenger
Services that are unchanged (except for a very small increase in fre-
flows, particularly during emergencies or abnormal traffic conditions. It
quency):
is intended to enable incidents to be detected and potential problems to
Radio Scotland (810kHz/37 I metres)
be anticipated, thus allowing remedial action to be initiated quickly and
Radio Wales (882kHz/34I metres)
station staff to be deployed more efficiently.
Radio Ulster (1341k Hz/224 metres)
Cameras viewing strategic areas at each station can be selected by
Radio 1 Bournemouth (1485kHz/202 metres).
means of a new I 2-input/8-output matrix designed and produced by
There are no changes to the BBC's VHF transmissions. Only the
British Relay. The matrix design also allows any one camera to be
BBC's MF and LF radio services are affected by the changes.
monitored by all outputs without deterioration of the composite video
signal.
Further details on the above changes and their effects can be ob-
tained from: Radio Changes, BBC, Broadcasting House, London W IA
4WW.
A number of additional transmitters are being installed and listeners
should not assume that their present reception of a particular frequency
is necessarily any indication of the reception it will provide under the
new plan. Maps are being prepared to show which frequencies are ex-
pected to provide the best service in each part of the country.
If you are considering purchasing a wireless and would like some
free advice on three -band receivers, aerials, car radios, tuning scales etc,
send a 9 by 6 in. S.A.E. to Engineering Information Department, BBC,
Broadcasting House, London WIA I AA.
The Beeb will send you a booklet with six pages of useful recommen-
dations, the most important of which is to get a three -band model.

HERE'S TO PROGRESS
RUSE your glasses-but don't drink! Not if you're driving anyway,
because technological progress might be waiting to nab you just
down the road. A new portable instrument is out which makes instant
'analysis of breath alcohol giving accuracy to within 12mg/m1 of actual
Local monitoring facilities are provided at Heathrow Central and blood alcohol level. There's no marching you down to the local "nick"
platform -only monitoring of all three stations is provided for the line for a blood test, and it wouldn't be much good pretending you were too
controller situated at Earls Court. weak to blow a bag up because your co-operation is not required, other
The transmission system comprises a wide -band 30 -MHz 3 -channel than to continue breathing. Indeed. the device can be used on the
stacked carrier multiplex system over a single coaxial cable running the unconscious.
whole length of the line between Earls Court and Heathrow Central (a The instrument, called the Alcolmeter type AE -M2, was invented by
type of system particularly immune from electrical track interference). Dr T. P. Jones, and a small hand-held version designed for initial
The carrier frequencies of the two existing channels employed are roadside screening purposes has been in production for nearly two
4.43MHz and 13.30MHz but a third channel of 24.7MHz carrier years. The new Alcolmeter overcomes the limitations in precision of the
frequency can be provided by the addition of an appropriate modulator pocket sized version while remaining small in size, completely portable
at the required locations and a demodulator at Earls Court. and very simple to use. The instrument enables on -the -spot breath
A feature of the system is that it can be easily extended by the alcohol analysis to be carried out by passing an accurately metered
addition of line repeater and directional coupler assemblies which volume of expired breath over a specially -sensitised fuel cell, housed in
would amplify and allow connection to other sites along the line without a hand-held unit linked to the equipment.
deterioration of the existing modulated composite video signal. The cell is activated by alcohol vapour and generates an electrical
British Relay are also supplying London Transport with CCTV signal proportional to the alcohol content of the sample. The electrical
switching and transmission equipment for other important central area signal is amplified and displayed on a panel meter.
stations including the new ones being built under stage -1 of the Jubilee The Alcolmeter is currently in extensive use with the Spanish police
Line. authorities and has also been accepted for use in Nigeria, Switzerland
Perhaps it will eventually become a way of life to be visually and several American states. The instrument is also widely used in
"monitored" whilst out and about. hospitals and alcohol clinics throughout the UK.

1090 Practical Electronics October 1978

 The Sinclair PDM35.
A personal digital multimeter for only £29.95 +1 8' VATI
Technical specification
DC Volts (4 ranges)
Range: I mV to 1000 V.
Accuracy of reading 1.0%± I count.
Note:10 M i t input impedance.
AC Volts (40 Hz -5 kHz)
Range: 1 V to 500 V
Accuracy of reading:1.0% ± 2 counts.
DC Current (6 ranges)
Range: I nA to 200 mA.
Accuracy of reading: 1.0% ± 1 count.
Note: Max. resolution 0.1 nA.
Resistance (5 ranges)
Range: lt t to 20 Mt t.
Accuracy of reading:1.5% ± 1 count.
Also provides 5 junction -test ranges.
Dimensions: 6 in x 3 in x 11/2 in.
Weight: 61/2 oz.
Power supply: 9 X' battery or
Now everyone can afford to Operation from replaceable battery Sinclair AC adaptor.
own a digital multimeter or AC adaptor. Sockets: Standard 4 mm for
A digital multimeter used to Industry standard 10 NI t t input resilient plugs.
mean an expensive, bulky piece of impedance. Options: AC adaptor for 240 V
equipment. 50 Hz power. De -luxe padded
Compare it with an carrying wallet. 30 kV probe.
The Sinclair PDM35 changes analogue meter!
that. It's got all the functions and The Sinclair credentials
features you want in a digital The 1'1)Ni 35's 1% of reading Sinclair have pioneered a whole
multimeter, yet they're neatly compares with 3% of full scale for a range of electronic world -firsts - from
packaged in a rugged but light comparable analogue meter. That programmable pocket calculators
pocket-size case, ready to go makes it around 5 times more to miniature TVs.The PDM35
anywhere. accurate on average. embodies six years' experience in
The Sinclair PDM35 gives you The PDM35 will resolve 1 mV digital multimeter design, in which
all the benefits of an ordinary digital against around 10 mV for a time Sinclair have become one of
multimeter - quick clear readings, comparable analogue meter - and the world's largest producers.
high accuracy and resolution, high resolution on current is over 1000 Tried, tested, ready to go!
input impedence. Yet at £29.95 times greater. When you buy your PDM35
(+8% VAT), it costs less than you'd The PDM35's DC input it comes complete with leads and test
expect to pay for an analogue meter! impedance of10 M tiis 50 times prods, carrying wallet and comprehensive
The Sinclair PDM35 is tailor- higher than a 20 kJ i/volt analogue operating instructions.
made for anyone who needs to make meter on the 10 V. range. The PDM35 is a new concept in
rapid measurements. Development The PDM35 gives precise multimeters - but over 20,000 have
engineers, field service engineers, digital readings. So there's no need to already been sold! If you'd like to know
lab technicians, computer specialists, interpret ambiguous scales, no more about the PDM35, and how to
radio and electronic hobbyists will parallax errors. There's no need to get one, complete the coupon and post
find it ideal. reverse leads for negative readings. it to us. We'll send you detailed
With its rugged construction There's no delicate meter movement information by return. Send the
and battery operation, the PDM35 is to damage. And you can resolve coupon today!
perfectly suited for hand work in the current as low as 0.1 nA and measure Sinclair Radionics Ltd, London Road,
field, while its angled display and transistor and diode junctions over St Ives, Huntingdon, Cambs., PE17 4HJ,
optional AC power facility make it 5 decades of current. England.
just as useful on the bench.
What you get with a PDM35 rTo Sinclair Radionics Ltd, London Road, St Ives, Huntingdon, Cambs., PEl7 4HJ.
31/2 digit resolution. Please send me more information on the Sinclair PDM35 personal digital multimeter.
Sharp, bright, easily read LEI) Name
display, reading to ± 1.999.
Automatic polarity selection. Occupation
Resolution of 1 mV and 0.1 nA Address
(0.00014A).
Direct reading of semiconductor
forward voltages at 5 different currents.
Resistance measured up to 20 Mi t.
I

L1E9
44)-kSinclair
World leaders in fingertip electronitsj
I

1% of reading accuracy.

1091
Practical Electronics October 1978
 Hair Trigger FRESNEL LENSES
SWITCH MATS 2 for £1.70 carr. & pkg 30p

6 or 12v. operation Supplied as two separate lenses or mounted

Size: together as condenser assembly - state pre-
29" x 16" ference. Slightly imperfect but entirely suit
approx. £1 J5pkg. 40p
able for IMAGE BRIGHTENERS. MAGNI-
FIERS, INTENSIFIERS. OVERHEAD AND

A Useful selections
of a wide range of
Wafer thin - undetectable under door mat or
carpet.
BACK PROJECTION OPTICS, CREATIVE
LIGHTING EFFECTS.

components, materials, PLASTIC TERMINAL MICROSWITCHES

etc., in convenient packs. BLOCKS useful pack of 8 switches, push to make
Just send £1 plus p&p. 5A, 2 -way. Pack of 20, p&p 20p. break or changeover, p&p 20p.

SLIDER POTS MODEL MOTORS

We pay UK postage & pkg. on
SAVE POSTAGE! orders FOR ANY 5 PACKS I
47KLin.; 100KUn.; 1 M Log.; 22 K Log.
Pack of any 4, state choice, p&p 15p.
11v. -41v., powerful compact units suitable
for wide variety of modelling applications.
Pack of 6. p&p 25p.
BARCLAYCARD AND ACCESS ACCEPTED - ORDER BY PHONE SELF TAPPING SCREWS
a generous 1Ib mixture of about 500 screws TRANSFORMER
OR POST. in useful sizes and lengths from lin., various double wound 240v. input, 12v. 200mA.
heads, p&p 50p. output. Size approx. 1/in. x 11in. x 11in. Pack
MAIL ORDERS TO PROOPS BROS. LIMITED. Dept. PE, of 2, p&p 55p.
The Hyde Industrial Estate, Edgware Road, Hendon, London, STEEL WASHERS
NW9 6JS. Tel. 01-205 8006. about 500 in a useful 20oz. mixed pack that REED SWITCHES
every tool box needs, p&p 50p. Ideal for burglar
PERSONAL SHOPPERS: 52 Tottenham Court Road, London, alarms, limit
W1 P OBA. 9-6 Mon. to Sat. SHAKEPROOF & STAR switches, position indi-
WASHERS cators. Introductory pack
about 500 in a good, varied selection of sizes, of 3 switches, rating 1A,
weighing 6ozs., p&p 20p. 3 circular magnets and 1
SPADE & RING SPACERS reed switch coil, p&p
CONNECTORS Pack of approx. 100, good selection of useful HOSECLIPS 20p.
as used in cars and domestic sizes, various lengths and diams.. p&p 25p. pack of 25 in assorted sizes from /in.. p&p
Pack of approx
appliances. 25p. CIRCULAR MAGNETS
llin. diem. with lin. square centre hole. Pack
100 connectors, balanced CROC CLIPS POP RIVETS of 20, p&p 25p.
selection, insulated and plain Pack of 16 14in. long, p&p 1 5p.
approx. 100 in balanced selection of 4 sizes,
p&p 25p. p&p 25p. DIODES
SPRINGS VIDAFLEX SLEEVING low powered germanium diodes. forward
generous and varied selection. compression
Pack of 4 x 25 yard lengths. 1.5mm bore. current 85mA. Pack of 25, p&p 15p.
and expansion springs, lengths from approx.
p&p 30p. SOLENOIDS LIGHT GUIDES
lin. to 2lin. and diameters from din. to 1lin. 11 volt. Small but relatively
yes, you can 'bend' light round corners with
Pack of approx. 100. p&p 25p. MAINS NEONS powerful solenoid with
these high quality glass fibre optics, 1 mm
in plastic holders. with leads and resistor. hundreds of uses for the
active area. 2 metres, p&p 15p; OR 2mm
RUBBER GROMMETS Pack of 5. p&p 1 5p. modeller. Overall size ap-
active area 1 metre. p&p 15p.
good selection, always useful for the prox. 25 x 26 x 10mm.
motorist, radio enthusiast, etc. Varied assort- MAINS NEONS Coil approx. 8mm diem. x 15mm JACK PLUGS & SOCKETS
ment. sin., Ain., lin. and llin. Pack of approx. miniature type with leads and resistor. Pack long. Range of travel (0.5mm approx.) can be 2 -way, pack of 4 plugs and 4 sockets p&p
200. p&p 20p. of 20, p&p 15p. varied if desired. Pack of 4, p&p 20p. 15p.

T.T.L. 74 I.C.'s By TEXAS, NATIONAL, I.T.T.,

7400 14p 7426 25p
FAIRCHILD etc
7473 30p 74121 30p 74151 65p 74179 140p
Connoisseurs New and
7401
7402
7403
7404
14p
14p
149
14p
7427
7428
7430
7432
25p
40p
15p
26p
7474
7475
7476
7483
30p
30p
30p
85p
74122
74123
74125
74126
40p
60p
50p
50p
74153
74154
74155
74156
SSp
120p
70p
70p
74180
74181
74182
74184
100p
200p
75p
150p
Exceptional SAU4
7405
7406
7407
7408
14p
40p
40p
20p
7437
7438
7440
7441
25p
25p
15p
65p
7485
7486
7489
7490
100p
30p
250p
35p
74130
74131
74132
74135
130p
100p
65p
100P
x74157
74160
74161
74162
70p
90p
110p
00p
74185
74188
74189
74190
150p
350p
350p
140p
Pick Up Arm
7409 20p 7442 65p 7491 759 74136 809 74163 ff0p 74191 140p Especially designed for modern high compliance cartridges and
7410 15p 7445 flOp 45p 74137 100p 74164 125p 74192 120p
7411 20p 7446 asp
7492
7493 40p 74138 125p 74165 125p 74193 120p featuring ...
7412 20p 7447 75p 7495 60p 74139 100p 74166 125p 74194 100p
7413 30p 7448 709 7496 70p 74141 Up 74167 32Sp 74195 100p 1. Light weight metal headshell
7414 60p 7450 159 74100 95p 74142 270p 74170 200p 74196 100p 2. Calibrated downforce pressure weight
7416 30p 7451 15p 74104 sop 74143 270p 74173 150p 74197 100p
7417 30p 7453 15p 74105 40p 74144 270p 74174 100p 74198 145p 3. Ball spirit level for visual indication of central balance.
7420 15p 7454 15p 74107 30p 74145 75p 74175 759 74199 185p 4. De -coupled counter balance weight
7422 20p 7460 15p 74109 50p 74147 230p 74176 100p
7423 2Sp 7470 30p 74118 90p 74144 160p 74177 100p 5. Viscous damped unipivot
7425 2Sp 7472 25p 74120 110p 74150 120p 74178 140p 6. Lateral balance weights
C. MOS. 2112-4 256 x 4 BIT 450 7. Viscous damped raise lower device
IN41 48 BY ITT/TEXAS 100
4000 14p 4030 55p for £1.50. NANO SEC. STATIC RAM 8. Light weight aluminium tube
4001 14p 4032 95p £2.95 each. 4/C11.60.
4002 14p 4033 120p UNENCODED 8/E22.80.
4006 90p 4047 100p HEXADECIMAL 19 KEY- 2513 CHARACTER
4007 16p 4048 55p BOARD. 1-10 A.B.C.D.E.F. 2 GENERATOR. UPPER CASE
4009 55p 4049 40p OPTIONAL KEYS. SHIFT KEY £7.00.
4011 14p 4050 40p
4054 120p £12.50. 2513 CHARACTER
4012 14p GENERATOR. LOWER CASE
4013 50p 4055 140p 555 Timer, 10 for £2.50. £7.00.
4015 90p 4056 136p
4016 40p 4060 120p 741 Op. amp. 10 for £2.00. MM5204AQ PROM 4096
4017 90p 4066 66p BIT READ ONLY MEMORY
4018 90p 4069 20p RCA SCR TO3 case £8.00.
4020 100p 4071 18p 100V 12.5A CUM.
4072 16p
8212 8 BIT IN/OUT PORT
4022 90p MURATA ULTRASONIC £3.00.
4023 16p 4081 16p
4082 16p TRANSDUCERS MA4OLIR 8831 TRI-STATE QUAD
4024 85p
4025 18p 4510 120p f2.50 each. £4.00 pair. LINE DRIVER £2.00.
4026 160p 4511 160p 8833 TRI-STATE TRANS-
4516 110p 2102AN-2L 1024 x BIT 1
4027 60p 250 NANO SEC. STATIC CEIVER (TRUE) £2.00.
4028 90p 4518 130p 8835 TRI-STATE TRANS-
4528 100p RAM. £2.20 each. 4/C8.40.
4029 110p 8/C16.00. CEIVER (INVERTING)
LEDS .125 OR £2.00.
.2 RED 2102AN-4L 1024 x BIT
UAR/T £6.00.
1

ONLY. 10 FOR £1.20, 100 450 NANO SEC. STATIC AY5-10 1 3

FOR [9.00, 1000 FOR RAM. £1.60. 4/C6.00. LM309K/LM340K VOLTAGE
C60.00 8/C11.60. REGULATOR £1 .00 each.

to' nnoirsew
CaI T. POWELL
306 ST. PAUL'S ROAD,
HIGHBURY CORNER, LONDON N.1
lLrIft lnr turthor II( tdilN to
A. R. Sugden & Co. (Engineers) Ltd.
Manufacturers of Connoisseur Sound Equipment,
Connoisseur Works, Atlas Mill Road, Brighouse, West Yorkshire HD6 1E5
Telephone: Brighouse (0484)712142, Telex: 517144 Sugden G
Telephone: 01-226 1489 Telegrams & Cables: Connoiseur Brighouse.
ALL PRICES INCLUDE POST AND V.A.T.

1092 Practical Electronics October 1978

 H
USE
YOUR FREE
A SHEET OF 120 STICKIES
WORTH 60p IS GIVEN
FREE INSIDE THIS ISSUE
No doubt you will by now have found
your free sheet of STICKIES. The ones you
have are for the popular 7400 series of TTL
i.c.s plus a few blank 14 and 16 pin ones
that can be filled in as required. Sheets of
CMOS (4000 series) are also available-
details later.

FAULT FINDING
Our photograph shows one of the main
uses of these labels. Having constructed a
piece of equipment it helps with circuit
checking and fault finding if each i.c. has its
corresponding label attached. Each pin
is then either labelled or its internal
connection is shown in schematic form.

P.C.B. LAYOUT
STICKIES are also very useful for
designing p.c.b.s. Simply stick them down
on a sheet of paper and join the pins with
pencil lines. They then provide immediate
identification of each i.c. and its pins and
form a reference for the i.c. size and pin
positions.

PROTOTYPING
Many amateurs and professionals
employ some type of plug in breadboard for
prototyping. When using unfamiliar i.c.s
STICKIES can provide an immediate pin
reference, helping to speed up interwiring
and eliminate mistakes. Of course once the
i.c. is labelled it can be used later and
the STICKIES will always provide pin
identification without recourse to charts or
reference books.

STORAGE
STICKIES should be stored away from
direct sunlight avoiding extremes of tem-

1093
Practical Electronics October I 97S
perature and humidity. The adhesive used is Str Strobe 7439 7401
a general purpose removable type which is V 7440 7420
Vcc
suitable for use between -40 and +70 Inverted functions are shown thus-T; for 7443 7442
degrees C. inputs this indicates active low, e.g. the cir- 7444 7442
The data printed on STICKIES has been cuit operates on the negative going transi- 7445 7442
carefully checked and is believed to be en- tion. 7447 7446
tirely reliable; however, no responsibility A broken division line is used on i.c.s 7451 7450
can be assumed for inaccuracies. which contain two circuits with identical 7454 7453
functions. Thus each function is connected 74132 7400
on one side of the line. 74145 7442
74161
ABBREVIATIONS 74162
74160
74160
Some abbreviations have been used on DIFFERENT I.C.s 74163 74160
STICKIES which may not be obvious to all
readers. These are: The STICKIES given in this issue cover
61 different i.c.s, however, by the use of the MORE!
Car Out Carry out "logically identical" table below this can be
Clk extended to 86 i.c.s.
We are sure you will find your 120 free
Clock
ones very useful and will in due course
Clr Clear FOR USE
EN
need some more. Please don't write to P.E.,
Enable 7403 7400
ext External
be thankful for the 60p's worth we have
7405 7404 given you and next time send your money
G GND 7406 7404
Inh
to Concept Electronics, 8 Bayham Road,
Inhibit 7409 7408 Sevenoaks, Kent. The cost, including an
(L) Left 7412 7410 information sheet, plastic wallet, VAT and
MOD Mode 7413 7420 postage is 80p for a sheet of 120 (either
Pre Preset 7416 7404 7400 or 4000 series-state which is
(R) Right 7417 7407 required).
Rst Reset 7422 7420 Alternatively, a 480 label pack is
Sel Select 7426 7400 available for £2.80. Concept will also give
SER IN Serial In 7437 7400
Sh Shift
discount for quantity orders, their 'phone
7438 7400 number is 0293 514110.

PATENT VICTORY

(News Oriels) HE JAPANESE Patent Office has issued a patent to Texas

I Instruments Inc. covering virtually all miniature electronic
calculators.
The patent is for personal -sized, battery -operated calculators which
have their main electronic circuitry in a single integrated -circuit chip.
The Japanese patent is based on US Patent 3,819,921, which was
by Mike Abbott granted to Texas Instruments on the 25th June, 1974.
The Japanese decision represents a significant milestone for Texas
TELETEXT COURSE Instruments because its pocket calculator invention was subjected to
stringent opposition by the patent system in Japan-where many
ou've probably seen Teletext by now, if not at an exhibition, then electronic calculators are made, and was determined to be patentable
y through a television dealer's window at least. Teletext could over opposition arguments.
become the newspaper and magazine of the future, and if you're still Official publication of the TI miniature calculator invention was
not clear how this potentially revolutionising advancement works, there made by Japan's Patent Office on the 24th August, 1974. Following
is still a chance to leap in on the course of lectures to be held at the this publication for opposition, 12 leading Japanese calculator
main building of the South London College. companies objected. They cited a total of 25 references as a basis for
This short course of nine special lectures on receiver decoders will be their argument that the TI invention was not patentable. The Japanese
held in the Lecturer Theatre on consecutive Tuesday evenings from Patent Office, on the 27th June, 1978, rejected the opposition
6.30 to 8.30, commencing 10th October 1978. Slides will be shown and arguments, awarding a patent to TI.
demonstrations given. Under the Japanese patent, Texas Instruments will have the right to
The course is intended for television and telecommunications claim royalties retroactively to the date that the TI miniature calculator
technicians and engineers, and will be presented by specialists from invention was officially published by the Japanese Patent Office. Texas
Industry and a member of the College staff, as follows: Instruments will actively seek to licence this patent.
C. J. Chapman of South London College, October 10 & 17: To date, 19 countries have issued patents to Texas Instruments for
Introduction to digital terminology. Topics to be introduced will the calculator invention, among them the United Kingdom.
include: binary codes, gates, counters, decode -of -count and memories. The miniature calculator described in the Texas Instruments patent
J. R. Chew of BBC Research Department, Tadworth, October 24: was the result of work done at TI in the mid -1960s. The US patent was
The Teletext signal; October 31: Character codes and generation. originally filed in 1967. This miniature calculator, the world's first,
Technical facilities available. employed a large-scale integrated semiconductor array containing the
R. Kinghorn of Mullard Central Applications Laboratories,
J. equivalent of thousands of discrete semiconductor devices. Measuring
Mitcham, November 7: Introduction to decoders-general only 108 x 155 x 44mm, it was the first miniature calculator to have
requirements for reception of teletext; November 14: The decoder the high degree of computational power, found at the time only in much
architecture; November 21: Data acquisition circuits; November 28: larger machines.
Memory circuits and character generation; December 5: Control of the Other elements of this early example of the miniature calculator
system. Likely developments. included a small keyboard with 18 keys and a visual display in the form
The course fee is £6.50, and early enrolment is advised. Contact: A. of a semiconductor thermal printer for printing out calculations ofup to
A. Rowlands, South London College, Knights Hill, London SE27 OTX. 12 decimal digits.

1094
Practical Electronics October 1978
 The
Prot° oard Now circuit designing
is as easy as
pushing a lead
into a hole.

No soldering.
No de -soldering.
No heat -spoilt components.
No manual labour.
No wasted time.

Contact terminals are arranged in sets of five, each

With a Proto-Board you can hook connected across the back, and in the Model 203A
your circuit together as quickly as you can illustrated you get 1770 contacts, in six rows of 59 x 5,
think. .
plus four double power rails, each with 100 contacts
And you can have second thoughts, and third connected lengthwise and two horizontal power units
thoughts, equally quick and easy, till you've got the whole thing with 40 contacts each. Many other models; see chart.
right. Proto-Board breadboards will accept transistors, ICs,
Then you can solder up if you want to, but most engineers don't because th LSI packages, resistors, capacitors, LEDs, trimmers,
Proto-Board push -fit connectors are highly reliable. relays etc.; most plug straight in.
And everything is visible: come back next week and you 'read' the circuit
immediately. Try one. You'll wonder how you ever
No. of IC Capacity Postage managed without it.
Model Solderless (14 -pin Unit Total
Number Tie -points DIP's) Price Package VAT Price Other features
PB-6 630 6 £ 9.20 £1.00 £0.82 £11.01 Kit -10 minute assembly
PB-100 760 10 11.80 1.00 1.02 13.82 Kit --with larger capacity
PB-101 940 10 17.20 1.25 1.48 19.93 &distribution buses, higher capacity
PB-102 1240 12 22.95 1.25 1.94 26.14 Large capacity, moderate price
PB-103 2250 24 34.45 1.50 2.88 38.83 Even larger capacity; only 1.73 pence per tie -point
PB-104 3060 32 45.95 1.50 3.80 51.25 Largest capacity; lowest price per tie -point
PB-203 2250 24 55.15 1.50 4.53 61.18 Built-in 1% -regulated 5V, 1A low ripple pbwer supply
PB-203A 2250 24 74.10 1.50 6.10 82.30 As above plus separate Y2 Amp +15V and -15V internally adjustable regulated supplies

How to order. Telephone 01-890 0782 and give us your Access, Barclaycard or American Express number, and your order will be in the post that
night. Or, write your order, enclosing cheque, postal order, or stating credit card number and expiry date. (Don't post the card!). Alternatively, ask for

=0=
our latest catalogue, showing all CSC products for the engineer and the home hobbyist. (Prices are for UK only. For Europe add 10%, outside Europe add 121/2%
to total prices.) CONTINENTAL SPECIALTIES CORPORATION
CONTINENTAL SPECIALTIES CORPORATION (UK) LTD REGISTERED IN LONDON 303780 VAT No. 224470 7471
SPUR ROAD NORTH FELTHAM TRADING ESTATE FELTHAM TRADE MARK APPLIED FOR ' CSC (UK) LTD 1977
MIDDLESEX TW1 4OTJE TELEPHONE 01 890 0782 TELEX: 881 3669 DEALER ENQUIRIES WELCOME
 SPECIAL OFFER TO P.E. READERS THE SINCLAIR PDM35
digital Multimeter
ALARM CHRONOGRAPH WITH DUAL TIME ZONE FACILITY
In a superb STAINLESS STEEL case with MINERAL GLASS face. Now a digital multi -
meter at an analogue
THIS MUST BE THE ONE YOU HAVE BEEN WAITING FOR! price and look at the
spec!
If you could write the specification for your own ideal D.C. VOLTS 1 rev -
1000v 11% .- 1 count)
watch you would probably want everything this one has. I Om° input.
As for styling, without a close inspection nobody is A.C. VOLTS 1,500v.
going to be able to tell the difference between this 401-1z-5kHz 11% 2
watch and that world famous James Bond classic counts).
selling for 145. However, this one goes one better and D.C. CURRENT 1 inA-
200mA 11% count).
has second measurement of net, lap and 1st & 2nd RESISTANCE 10-
place times, with dual time facility. 20m0 I I 5%+1 count/.

Constant LCD display of hours and minutes, plus £27.95 inc. VAT
cash with order complete
optional seconds or date display, plus day of the with test leads, prods &
week and am/pm indication. wallet, De -luxe padded
case f3.25
Perpetual calendar; day, date, month and year.
24 hour alarm with on/off indication. SINCLAI R DM235
45 second chronograph measuring net, lap and first Portable 31 digit 6 function
and second place times. Multimeter.
DC volts lmV to 1000V
Dual time zone facility. Night light. AC volts lmV to 750V
Fully adjustable stainless steel bracelet. AC & DC current 1 p A to IA
Resistance 10 to 20M0
STAINLESS STEEL CASE. MINERAL GLASS. Diode test 03 1 A to 1 mA
I Om° input, DC acc. 1.0% AC
This watch is not to be confused with cheaper models acc 1.5% 30Hz-10KHz
reliability, with undeniable value for money. Cash with order
with chrome plated cases and plastic lens. The first very limited quota will be available in mid -
Manufactured by National Electronics, it runs a close September with a few more due in October. Orders will £52.80 inc VAT complete with test leads & prods
second to Casio, Citizen and Seiko for quality and be treated in strict rotation, so don't risk being A full range of optional accessories. (Prices include VAT)
disappointed. Eveready carrying case with lead storage compartment....£8.96
OTHER LOW COST Rechargeable battery units £8.50. AC adaptor/charger
NATIONAL WATCHES 240V 50 Hz £3.50. 30kV voltage probe £18.04
PH -GI
4 digits
PH -Chronograph 011CQ-81 CALCULATING
All Prices include
To all Orders.
VAT. Add 50p. Postage and Packing

5 functions 6 digits ALARM CLOCK Aiso Available: The New Computer Chess Challenger with
TEN levels of play £199.95. SAE
all metal 45 second
net, lap and PLUS 2 Sinclair Pocket Television. £199.95. SAE
1st & 2nd place ALARM/TIMERS Computer Backgammon f149.95. SAE
Two AA batteries last for The NEW ELMAC 4" oscilloscope £109 inc. VAT P&P.SAE
£18.95 10,000 hrs (1 year). LCD Heavy duty prom eraser £56 + VAT. SAE.
6 digit clock, large angled Full range of support chips e.g. intel 8080 £8 inc VAT. SAE.
display. 24 hr Alarm, also Intel MCS/8131SDK) kit £190 + VAT. SAE.
two 24 hr Alarm/timers Send cheque with order to:
with countdown lone self - GEMINI ELECTRONICS
clearing, one repeats). Full
Memory, Constants, %, Newton Buildings
1g° x 2 x 5in. Newton Street
Manchester. Tel: 061-236-3083
MAIL ORDER ONLY
RRP £22.95 £17.95

PH -Alarm
Hours, mins,
N -T E R L -O C K -I -N G
secs or date,
PH -Analogue
ST -24 CARD TIME 1 PLASTIC STORAGE DRAWERS
day, am/pm.
Calenda (perp.) Stepping motor 24 hour stopwatch
24 hour alarm Day, date. (or time display)

£29.95
Sweep seconds sec. to 10 hours
1 second to 24 hours orfse
£24.95 Two Alarm/Timers
Memory, %,
ex33x2,1in. DISCOUNT
AQ-1000 CALCULATING
ALARM CLOCK PLUS
RRP £24.95 PRICES
£19.95
3 -WAY STOPWATCH Newest, neatest system ever
devised for storing small
Hours, minutes, seconds, am/pm. 24 1 parts and components: resistors.
hour Alarm with sign. Stopwatch: Net aoaa THE INCREDIBLE capacitors, diodes. transistors. etc. 5 SIZES
times, lap times, 1st & 2nd place times aaaa a Rigid plastic units interlock together in All. INTERLOCK
from .4sec. to 10 hrs. with ST & LAP !LP_ _E. 2 .2 FX 8000 vertical and horizontal combinations.
signs. Calculator: 4 key memory, %,
1 year batteries. ±20 secs/month. ', czzampazirs- 43 Scientific funct.
Transparent plastic drawers have label slots 10 and 2D
have space dividers. Build up any size cabinet for wall,
th sec. Stopwatch. bench or table top.
x 21 x 411in. Five Alarm -Timers, As supplied to Post Office. Industry and Government Depts.
RRP £26.95 Our price £21.95 sequential (self -
clearing) or repeat. SINGLE UNITS (1 DI 15in x 21in x 2}in) £3.50 DOZEN.
2 level parenthesis. DOUBLE UNITS (20) (5in x 4}in x 21in) £5.50 DOZEN.
NEW CASIO WATCHES Memory. Deg, Rad, Gra. TREBLE (301E5.50 for B.
Experience has convinced us that for quality DOUBLE TREBLE 2 drawers, in one outer case 103021,
Standard Deviations. £7.90 for 8
reliability and value for money, CASIO are unbeatable. Fractions. Sexagesimal. EXTRA LARGE SIZE 161311 (6.90 for 8
CASIO have now increased their superb range. Rect/Polar convert.
All CASIO watches have a calendar display, night LCD. 1300 hr batteries. PLUS QUANTITY DISCOUNTS
x 21 x 51in. 2.7 oz. Orders over £20, less 5%. Orders over £60. less 71%. PACK-
illumination, mineral glass and stainless steel cases, ING/POSTAGE/CARRIAGE: Add E1.00 to all orders under
water resistant to 100 feet (except Sports Watches - RRP £35.95 E10. Orders El 0 and over, please add 10% carriage.
66 feet). £29.95 QUOTATIONS FOR LARGER QUANTITIES.
Please add 8% V.A.T. to total remittance.
31 QR-20B Round, Stopwatch (E31.95) £26.95 All prices correct at time of going to press.
51 QR -19B Round, 6 Digits,
Selectable 12 or 24 hour display 1E35.951 £29.95 ALARM WATCHES. 25CR-1613 (round) £49.95
25CS-14B (square) £59.95 4 WAY aliNE PATENT
54QS-168 Square, as above 1E44.951 £34.95 1N -LINE CABLE
54QS-158 Luxury version
45CS-22 BChronograph. Net,
(E49.95) £39.95
WORLD TIME WATCH. 29CS-11B £59.95
SEIKO Calculator/Watch (£ 165) £135
CITIZEN Multi -Alarm (E135) £108
13 AMP AN" LOCK

lap and 1st & 2nd place times. 12 or MAINS DIGITAL ALARM CLOCKS NEON INDICATOR 111
24 hour display. Dual time zone (E64.95) £49.95 Fairchild Timeband C500, Black or white £9.95 LINP
Dress Watches. Square, stopwatch, dual time zone CASIO CALCULATORS
53CS-188 Square £54.95 ST -1 Stopwatch (four way) £24.95
(E69.95) LCD LC822 £10.95. LC78 £16.95
53CS-19B Barrel (£69.95) £54.95 EASILY
53CGS-17L Gold plated strap (£84.95) £69.95 AQ-1000 Clock, alarm, stopwatch C21.95
All these models and full details should
CASIO SCIENTIFICS
DIGITRON: FX-31 £11.95. FX-39 £15.95. ~sawn. ACCESSIBLE

be available in early September. FX-140 £17.95. FX-120 £19.95. FX-360 £49.95. oR matt le
Modern, slim -line power panel, countless uses in home.
RISE

Send 25p for our illustrated catalogue. Accurist, Casio, Citizen etc. office, factory. showrooms. Perfectly safe, unbeatable. Can
be mounted on wall or trailed anywhere in room. Neat
Prices include VAT P.&P. Send cheque, P.O. or phone your credit card No. to: rubber base. Smart PVC outer cover. Black £3.10.
White £3.30. P&P 60p each.

TEMPUS Dept. P.E., 19/21 Fitzroy Street

Cambridge CBI 1 EH, Tel. 0223 312866
FLAIRLI NE SUPPLIES (PEio)
124 Cricklewood Broadway, London N.W.2
Telephone 01-450 4844

1096 Practical Electronics October 1978

 And so the mistakes of the past are likely surprisingly, radio receivers will also do
to be repeated with much talk and little or well. Table -top monochrome TV sets,
no action and in a technological situation in however, will virtually become extinct ex-
which hardly a day passes without advance. cept for the poorest homes in the poorest
One rumoured plan for Britain is to set up areas. The growth forecast is based on the
00 0 and finance a mass -production unit for the assumption that Western Europe is not yet

:t MM
64K RAM market and site it in a depressed
area. Even with technical assistance from
Silicon Valley it is extremely doubtful
market -saturated in consumer electronics.
Meanwhile UK suppliers continue to
have a rough time. Even well -managed
GEC lost £4 million on TV last year and
whether production could be obtained in
meaningful quantity by the time that others after drastic action to remedy over-
are working on the 256K RAM, expected to capacity only a break-even situation is
be on the market in a big way by 1982. forecast for this year.
As far as MPUs are concerned the
proposed government aid aimed at en- Encouragement
couraging their application in new products The Caroline Haslett Memorial Trust and
should be well worth while. The MPU is just the Institution of Electrical and Electronics
another chunk of silicon, worthless until it Technician Engineers are putting up an an-
is programmed to a useful activity. The nual award of £250 for "The Girl Techni-
hardware costs are dropping dramatically cian Engineer of the Year". The idea is to
while programming costs are relatively in- draw attention to electrical and electronics
creasing. It will be the ingenuity in engineering as a worthwhile career for
programming and application that could young ladies.
keep Britain ahead in world trade.
One positive step forward in the Great Fibre -Optic TV
Debate is that the Government has now
come to recognise that there is an elec- Following long experimental tests of TV
tronics industry in Britain and, moreover, signal distribution by fibre -optic link in the
that it is important. And that can't be bad. UK by Rediffusion, the first consumer
The Great Debate (2) household in the world to receive its TV
Since my comments last month on VLSI signals by fibre -optics is in Arnhem,
and its probable impact on life-style in the Postal Automation Holland. The local company, Delta Kabel, is
1980s and beyond, the Government have The introduction of automation in the using the Dial -A -Program system
made a few announcements of intended aid postal services is going at a snail -like pace developed by Rediffusion and operated by
to microelectronics producers and users. according to a Mr J. Gombinski in a recent Delta Kabel under licence.
The Government's response, such as it is, letter to The Times. Although a little out-of- The optical link into the house is about
is feeble in terms of financial aid and date (being based on information disclosed 800 feet long and is intended to
appears uncertain in intent. But can the in 1975) his statistics are worth repeating. demonstrate that the idea is not only
Government be blamed when its input of Nine years after the introduction of workable but can be achieved with low-
information, not to mention advice, automation, writes Mr Gombinski, only six cost components. Signal distribution by
from well-meaning sources is itself per cent of machinable mail was sorted light duct could prove cheaper than copper
confused and influenced, not by a master - automatically and at the then rate of wire and, having a wider bandwidth, will
plan carefully conceived for Britain, but progress it would take 150 years to accommodate many more TV channels as
largely by what other countries are doing? automate entirely. But while the Post Office well as stereo radio.
Of course it is correct and prudent that hardly ever uses the postal codes he
we should keep an eye on what our com- calculates that in 1975, given 150,000 Satellite News
petitors are doing but the level of govern- million machinable items a week and allow-
ment aid granted in Japan or France, West ing only 3 seconds to write in each of the Marconi Space and Defence Systems
Germany or the United States is not unused codes, 750,000 working days were has won an order worth £12 million for two
necessarily the yardstick we need to adopt. lost on a useless exercise in that year alone. new transportable earth terminals for
A logical argument is that if VLSI is going to NATO and for updates on a dozen existing
be a winner, then there should be plenty of earth terminals. The contract also includes
private investment to support it without Talking Computers the supply of the same updating equipment
state aid. Unhappily there are other factors Racal-Milgo could be on to a good thing for five terminals being built in the USA by
such as national self-sufficiency in the taking on the marketing of Wavetek voice Ford Aerospace.
equation, and the high -risk element which response systems in Europe, the Middle Racal Electronics Group, better known
deters private investment. Until some more East and Africa. The system allows you to for manpack military radios and h.f.
clearly defined policy emerges it is dial up a central computer by ordinary receivers and transmitters, has broken
reasonable that the few million pounds so telephone, use a low-cost key -pad to enter through into mobile satellite ground ter-
far tentatively committed should be your enquiry and the computer supplies the minals with a substantial order from the
received with grateful thanks and in the answer, not in data form but in a simulated Ministry of Defence. The Racal design is a
hope that more is to come. human voice. It is a fast -response system, small terminal which can be accom-
I remember ten or more years ago we all especially useful for verifying whether a modated in light field vehicles such as the
went through the same painful exercise in credit-card customer is in credit and for Land Rover.
the early days of the integrated circuit. similar routine enquiries. Transatlantic communications, shared
There was endless debate about what amicably over the past few years by com-
should be done and in the end the industry plementary submarine cables and Intelsat
verdict was "too little and too late". The Consumer Market satellites, is now the subject of dispute. In-
Today, we are going through even more If market analysts Frost & Sullivan are telsat want a larger share of the traffic and
agony because we have an even greater right in their forecasts, the consumer elec- the FCC is objecting to further cables, such
proliferation of official committees, working tronics market in Western Europe is now as TAT -7, which would increase cable
parties, think tanks, and other experts in- due for a revival. Predictably the growth capacity. Europe wants the new cable. So
volved, not to mention powerful voices areas will be in the newer fields of does the US Defence Department who see
from non -experts like the unions and less - videotape recorders, TV information ser- the transatlantic cable as a necessary back-
powerful but nonetheless influential TV and vices and TV games. Music centres are also up should the satellites be blown out of the
radio commentators. tipped for big gains by 1985 and, perhaps sky by possible enemy action.

1097
Practical Electronics October 1978
 MI CRO****BUS
Compiled b9 DJD.
Appearing every two months, Micro -Bus will present ideas, applications, and programs for the most
popular microprocessors ; ones that you are unlikely to find in the manufacturers' data books. The most
original ideas will probably come from readers working on their own microcomputer systems, and
payment will be made for any contribution featured here. This is also the place to air your views, in
general, on this new technology, so let's be hearing from you!

THE THREE topics in this month's Micro -Bus and so on this side the hardware was made as helps in setting up the best level at the input
are all concerned with minimization in simple as possible. The programs were written potentiometer."
some way or other, with a supremely simple to be relocatable so they can be fitted
cassette interface system, some improvements anywhere in memory without modification." LOAD PROGRAM
to the number -sorting routines given in April's
Micro -Bus, and a diminutive program for RECORDING FORMAT "The LOAD program in Fig. 3 operates as
finding prime numbers.
follows. It first waits in a loop for an input at
"Data is coded as a series of 1kHz tone SENSE -B. On receipt of an input it delays for
MINIMAL CASSETTE INTERFACE bursts; a zero bit is represented as a 4ms burst 14msec. and then shifts whatever is present at
followed by a 28ms gap, and a one bit is coded SERIAL -IN into the extension register using
The cassette interface system to be as a I6ms burst followed by a 16ms gap. The the SIO instruction; this will be a 0 if the pulse
described was received from Nick Toop of bytes are transmitted low -order bit first, was short and a 1 if the pulse was long. The
Cambridge, and it overcomes one of the main and there is no extra gap between program delays for a further 14msec. and then
drawbacks of the lower -cost microprocessor successive bytes. To load from tape the start returns to the previous loop.
kits currently available; namely that they address is first entered at OFF9 (high -order "When eight bits have been shifted into the
provide no way of permanently saving byte) and OFFA (low -order byte) so that the extension register the byte just formed is
programs. The system described makes it monitor will put the address in P 1 on entering stored to the location pointed to by P1 using
possible to store and load programs and data the program. auto -increment addressing so that PI is then
using a standard domestic cassette or tape "In systems without a monitor some in- pointed to the next address. When the in-
recorder, and although it is primarily designed structions will have to be added at the start of dicator l.e.d has stopped flashing the reset but-
for SC/MP, it should be possible to develop a the program to set up P1 correctly. The tape is ton on the microprocessor should be pressed
similar system for use with any other played until the blank interval in front of the to escape from the program, and loading is
microprocessor. data is reached, and then the LOAD program complete.
"The cassette interface and programs were is executed. The tone bursts from the tape are "Since the load program allows you to
originally designed for use with a SC/MP In- processed by the circuit of Fig. 1 which uses a specify any arbitrary starting address for the
trokit with the Keyboard Kit, but they are single 4001 (or 4011) CMOS gate package data being loaded, the cassette system also
currently being successfully used with a with the four gates wired as inverters. serves as a means of relocating programs in
Science of Cambridge Mk14. The main objec- "The first inverter is biased into its linear memory."
tive in developing the system was to make the region to act as a simple amplifier, and two
load -from -tape program as short as possible more inverters form a demodulator which STORE PROGRAM
since this would have to be entered at the gives at its output the squared -up envelope of
keyboard on powering up each time. the pulse bursts. This is fed to the SENSE -B "To store to tape the start address is put at
"On the other hand the length of the store - and SERIAL -IN inputs of the SC/MP OFF9 (high -order byte) and OFFA (low -order
to -tape program is not so important since this microprocessor, and to an indicator I.e.d. byte), and the number of bytes to be stored is
can be loaded from tape each time it is needed, which flashes to indicate correct operation and put, in hex, at OFFB; the address and length

Fig. 2. The store -to -tape circuit, a

simple adder which combines two
signals from the microprocessor
Fig. 1. Nick Toop's load -from -tape circuit, a demodulator using a single
CMOS package

1098 Practical Electronics October 1978

 are loaded into P1 and P2H respectively by together with the claim that they were believed necessary to test them. This improvement can
the monitor program. The maximum length is to be the shortest programs possible. It now be incorporated in the program of Fig. 5 with
256 bytes, represented as X'00. seems that this was a dangerous claim to no increase in size simply by changing the
"The STORE program of Fig. 4 codes the make, and thanks are extended to all the instruction at 0014 to "JR NZ, SORT -S", and
data into a sequence of tone bursts at the readers, too numerous to mention, who sent in in the program of Fig. 5 by changing the posi-
FLAG -0 and FLAG -1 outputs on the SC/MP improvements. tion of the label AGAIN to the instruction
chip. FLAG -1 is set high between bursts so The sort routines all used the exchange -sort "DEC A" in the previous line.
that when the two outputs are combined at the method to order an array of up to 256 num-
input of the tape -recorder using the simple bers, and the condition was made that the ad-
adder circuit of Fig. 2 the gap between pulses dress and length of the array should be passed PRIME PROGRAM
is at a mean level; this avoids sharp transients down to the routine in suitable registers. The Although the prime numbers are simple to
due to the pulse onsets which would make an routine for the Z80, which was taken from the define-they are numbers whose only divisors
automatic volume control adopt an unduly Z80 -CPU Technical Manual, received the are 1 and the number itself-no explicit for-
low sensitivity. greatest hammering and the shortest version, mula exists for generating them, and efficient
"The program generates either four pulses sent in by Eric Baddiley of Cheshire, reduces programs to search for particular primes can
for a zero or 16 pulses for a one, using the the number of program bytes from 38 to 231 be extremely complex. Note that 1 is not con -

.TITLE 'LOAD FROM TAPE'

' PUT IN MEMORY STARTING AT ADDRESS IN PI
1-80 SORT ROUTINE
0000 ..OF7F ADDRESS OF DATA IN REGISTER HL
OF7F ;SIT COUNTER NUMBER OP BYTES IN REGISTER C
COUNT; RELOCATABLE
BEGIN EXECUTION HERE .TITLE 'STORE TO TAPE'
OF80 C408 LOAD, LDI 8 'BIT COUNT I PI CONTAINS START ADDRESS 0000 OD SORT DEC C ADJUST COUNT
OF82 C8FC ST COUNT I P211 CONTAINS LENGTH 0001 15 AGAIN PUSH HL SAVE HL
OF84 06 LOOP: ANA 0002 41 LD B,C RESTORE COUNT
OF85 0420 AND X.20 'SENSE -13 INPUT 0000 ..0F9D 0003 16FF LD D,OFFH RESET THE FLAG
OF87 98FB JZ LOOP ;NOTHING FOUND OF9D 0005 le NEXT LD A,(HL) GET FIRST ELEMENT
PULSES, ...41 'PULSE COUNTER
OF89 8F1C DLY ;WAIT OF9E 0006 23 INC HL POINT TO NEXT
MASK: .41 0007 BE
OF813 19 SIO ;SHIFT INTO E -REG OF9F LEN: CP (HL) IN THE RIGHT ORDER?
.41 'LENGTH COUNTER 0008 3006
OF9C 8F1C DLY X.1C ;WAIT FOR GAP JR NC,NOEX-$ IF YES THEN JUMP
OF8E 138F0 OLD COUNT
000A 58 CO e, (HL) ELSE SNAP THEY
I BEGIN EXECUTION HERE 0008 77 LD (HL),A
OF90 9CF2 JNZ LOOP OFAO 36 STORE, XPAH 2 'GET LENGTH 0000 2B DEC HL
OP92 40 LOB 'GET BYTE INPUT OFA1 COED ST LEN 0000 73 LD (H1..),E
OF93 C001 ST LO(1) 'STORE IT OFA3 02 CCL 000E 23 INC HL
OF95 90E9 JMP LOAD OFA4 C501 SCANT LD 81(1) ;PUT NEXT BYTE 000? 14 INC D AND SET THE FLAG
OFA6 01 XAE I IN E-REG. 0010 10F3 NOEX 0591 NEXT-$ LOOP IP MORE DATA
0000 .190 OFA7 C401 LDI X.01 ISET MASK 0012 El POP HL RESTORE HL AND SP
OFA9 C8F4 NEXT, ST MASK 0013 14 INC D TEST THE FLAG
OFAB 50 0014 20ES JR NZ,AGAIN-$ DO AGAIN IF SWAPS
ANE 'GET ONE BIT
Fig. 3. LOAD program for SC/MP OFAC
OFAE
9804
C410
.12
LDI
ZERO
X.10 'STORE
0016 C9 BST ELSE RETURN

which loads data into memory from OFB0

OFB2
9002
C404 ZERO,
JMP
LDI
STORE
X.04
APPROPRIATE
NUMBER OF
a tape using the format described in ORB/
OFB6
C8E8
C403
STORE:
REP,
ST
LDI
PULSES
X.03
t PULSES. Fig. 5. Eric Baddiley's improved sort
the text OFBB 07
8F01
CAS
DLY X.01
'FLAGS 0 AND 1 routine for the 280 micro
OFBB 0400 LEI X.00
OFBD 07 CAS 'FLAGS OFF
OFBE 8F01 DLY X.01
NAN SORT OFCO B8DC DLD PULSES
. ENTRY: x CONTAINS START ADDRESS OF ARRAY OPC2 9CP2 2ND
. A CONTAINS NUMBER OF ELEMENTS REP 'PULSE BURST
OFC4 C401 LDI X.01 'MEAN LEVEL
OFC6 07 SUBROUTINE TO FIND X-TH PRIME
CAS BETWEEN BURSTS.
0000 0082 PTR Rae 2 ;
RESULT RETURNED IN Y
OFC7 CODS LD MASK
OFC9 50 (ASSUMED LESS THAN 255)
0002 OF 00 SOFT STY FOR SAVE START ADDRESS ANE 'INSERT
0004 44; DEC A NUMBER OF PAIRS OFCA 9CO2 JNZ ONE ' APPROPRIATE 0000 TRY ...41
0005 36 AGAIN ERR A SAVE ON STACK OFCC 8F18 DLY X.18 TRAILING
0006 59 CLR B EXCHANGES FLAG OFCE 8F20 ONE, DLY X.20 ' SPACE. 0001 D8 START CLD CLEAR DECIMAL MODE
0007 DE 00 COX PTk SET START ADDRESS OFDO COLD LD MASK 0002 AO 01 LOY El
0009 36 NEXT PSH A SAVE COUNT OFD2 POCK ADD MASK 'ADJUST MASS FOR 0004 C8 COST INS
000A A6 00 LDA A 0.0 COMPARE TWO ITEMS OFD4 9CD3 JNZ NEXT I NEXT BIT. 0005 84 00 STY TRY NEST CANDIDATE
0000 Al 01 CMP A 1.4 OFD6 B8C8 DLD LEN 0007 9B NEXT TYA
000E 23 0. BLS NOSSAP JUMP IF FIRST (= SECOND OFD8 9CCA JNZ SCAN 'READ NEXT BYTE? 0008 C6 00 DEC TRY SET UP DIVISOR
0010 30 PSH 0 SWAP ITEMS OFDA 3F XPPC 3 'GO TO MONITOR 000A 38 SEC
0011 E6 01 LDA V 1,1 0008 90 FA SUB BCC NEXT REMAINDER
0013 Al 01 STA A t.x 0000 .END 0000 E5 00 SBC TRY
0015 E7 80 STA R 0.1 000F DO FA BNE SUB
0010 33 PUL 0 RESTORE PLAN 0011 C6 00 EXACT DEC TRY WAS DIVISOR I?
0018 SC INC B EXCHANGE DONE 0013 DO EP BNE COST
0019
001A
08
32
NOSKAP INX
FUL A
STEP POSTER
GET COUNT Fig. 4. STORE program for SC/MP 0015
0016
CA
DO EC
PRIME DEX
ONE COST
MORE TO FIND?
0816
0014
48
26 ER
DEC
BNE
A
NEAT LOOP UNTIL END OF ARRAY which encodes data from memory 0018 60 RTS RETURN - PRIME IN
0010
001F
32
5D
PUL
TST
A
B
RESTORE COUNT
as a series of tonne bursts .END

0020 26 E3 BNE AGAIN LOOP IF EXCHANGES DONE

0022 39 RTS ELSE RETURN

END Fig. 7. Program for the MC86502

which finds the nth prime number
Fig. 6. Andrew Yeomans' improved given n
version of the M6800 sort routine

location PULSES as a counter; the pulses are The new version, shown in Fig. 5, has the sidered to be a prime, so the first eight primes
followed by the appropriate trailing space, added advantage that it is relocatable because are 2, 3, 5, 7, 11, 13, 17 and 19. Consider the
namely 28ms for a zero and I6ms for a one. it makes no use of external store to hold data. task of writing a routine to fmd the n'th prime
Eight such bursts of pulses encode each byte A similar version was received from D. where n is passed down in a suitable register.
of data. Ritchie of Essex University. ,A surprisingly short program will achieve
"As you can see, the recording format is The shortest sort routine for the M6800 this if efficiency is not important, and Fig. 7
extremely simple, and this helps to make the was submitted by Andrew Yeomans of Surrey, shows one for the MCS6502 which will find
software short and the hardware cheap. and this is shown in Fig. 6. It reduces the size all the primes up to 251, the 54th prime. The
Nevertheless the system has proven extremely of the program from 41 to 33 bytes by making number of the prime required is supplied in the
reliable even with a low-cost cassette recorder, use of the stack to store temporary variables. X register and the prime is returned in the Y
and it is amply fast for most purposes, loading Michael Blanclford of Dorset pointed out register. By altering the program to use
or storing 256 bytes in under a minute." that the sorts can be speeded up by double -byte variables it could easily be exten-
decrementing the length of the block to be ded to fmd primes up to 65535. As it stands it
scanned after each pass; after one pass of the is hard to see that the program could be shor-
BETTER SORTS array the last element must be in its correct tened, but readers who find improvements are
In the -April Micro -Bus number sorting position, and after 20 passes the last 20 ele- encouraged to send them in and some may be
routines were given for four different micros ments must be in order at the end, so it is un- presented in a future issue.

Practical Electronics October 1978 1099

 `WWI

1MEI El CI
Copies of Patents can be obtained from :
the Patent Office Sales, St. Mary Cray, Orpington, Kent Price 95p each

IMPROVING "MUSICALITY"

In the hi-fi world there is currently con- The audio amplifier of Fig. is based on
1 capacitors 23, 25 are of Mylar film type and
siderable controversy over the "musicality" FETS 12, 13 in a complementary pair. Elec- similar value.
of amplifiers, that is to say the possibility trolytic capacitors 20, 21 are used as filters According to the inventor, "nothing is
that two amplifiers which measure the for the d.c. source and also for decoupling. known about what effect is exerted on
same on even the most sophisticated test The capacitors are formed of an aluminium sound signals by the non -linearity of the in-
equipment currently available may sound film and are of high value e.g. 5,000 to ner loss of the capacitors relative to audio
different when reproducing music. In 20,000µF. To capacitor 20 is connected in frequency" but he believes that electrolytics
BF 499 939 Tokyo Shibaura Electric
1 parallel a pair of nonpolar capacitors 22, 23 as used in audio amplifiers are non-linear in
Company Limited of Japan patented an and to capacitor 21 is likewise connected a this respect.
amplification circuit that is claimed to give pair of nonpolar capacitors 24, 25. The He also believes that the connection of
improved results, through a particular con- capacitors 22, 23, 24, 25 are each chosen various given types of nonpolar capacitor in
nection of capacitors, but with the admis- to have a capacity which is sufficiently low parallel with the electrolytics causes the
sion by the inventor that it is unclear why to leave the capacity of the electrolytics 20, collective inner loss -frequency charac-
the improvement is achieved. 21 largely unaffected but sufficiently large teristics of all the capacitors to be linear
Essentially the claim is that the connec- to allow a substantial proportion of the over the audio range. The number of non -
tion of extra nonpolar capacitors parallel audio frequency range to pass through polar capacitors is not limited to two, and
with the electrolytics "can effectively im- them. three or more may be used as necessary to
prove the fidelity of reproduction", although Capacitors 22, 24 are of metallized paper provide linearity.
the reason why "is not theoretically clear". in the value range 10 to 100µF and the

0
Cc

0 1000
10 100
Fig. 2 FREQUENCY (KHz ) Fig. 4

1100 Practical Electronics October 1978

 EMI Ltd. in BP 1 497 394 describe an in- RUMBLE ERADICATION
teresting approach to the eradication of low
frequency noise or rumble from recorded or
transmitted signals. The invention makes
use of the fact that little or no directional in-
formation is derived from low frequency
signals. EMI put the dividing line between
high and low frequencies at 200Hz and
although it is arguable that this figure is too Fig. 1
high (i.e. that frequencies below 200Hz can
carry directional information) this argument
does not effect the basic theory of the in-
vention.
As shown in Fig. the recording or
1

transmission system is fed with left and

right channel signals L and R, each com-
posed of high and low frequencies. Thus 1
L =1_, + L1 and R = Rh + Rh The signals in 7\ LH + LL + r LH -i-ILL+RLI
the left channel (Lh +1_,) frequency
modulate a carrier frequency, eg. at DEMOD

300kHz, in modulator 3. The signals in the 112

REPLAY MATRIX
right channel are inverted at 4 and the in- [13
verted signals (- Rh - 131) frequency IHV
modulate at 5 a carrier of the same (or dif- H DEMOD
ferent) frequency. The frequency modulated
signals are recorded at 6, which may be an Fig. 2 9l/ r 10, RH -FRL-r
f.m. tape recorder or disc.
The reproduction circuit is shown in Fig.
2. The f.m. signal is first demodulated at 8,
9. The demodulated signals will inevitably
now contain some unwanted low frequency 14

noise which is represented by r. Because

the two recorded channels have been
derived from the same tape track, or record
groove, the rumble components are vir-
tually identical in magnitude and phase.
Thus the signals in the left channel are, af-
ter demodulation, (Lh + L1 + r) and the
signals in the right channel are
(- Rh -R1 + r). The right channel signals are
now inverted to produce (Rh + R, - r) so that
the rumble components r in the two chan-
nels are now in exact anti -phase. They can
thus easily be removed by the matrixing cir-
cuit 11. The final output is thus free from all
the low frequency noise introduced by the
process.

An idea for a meter which automatically RANGE CHANGING

changes scale to avoid under and overload
and provide the most accurate read out
available, is patented by Lawrence Large of
Sussex in BP 1 507 466. Although the idea
is simple it could well prove valuable.
As shown the meter scale has a per-
1

foration 2 at the "higher" end. A photoelec-

tric cell 7 lies underneath this perforation
and normally receives light from source 8.
The meter pointer carries a blanking plate 3
which is dimensioned to obscure the per-
foration 2 as soon as the pointer is driven
towards the dial stops. In this way light to
the photo cell is blocked and this change of
state is sensed to switch the meter scale to
the next higher range.
A similar approach can be adopted at the
low end of the scale with obstruction of
another light path sensed to switch the
meter down to a more sensitive scale. If
successfully adopted such a system could
prevent overload of a dial meter while at
the same time optimising accuracy by
selecting always the most sensitive, but
safe, scale for the reading in hand.

Practical Electronics October 1978 1101

 DISC FULL OF HOLES

News Briefs) MANY developments have been made over the last few years on
various picture recording and playback systems for television. In
1968, THOMsON-CSF considered that one of the best ways to solve
this significant problem and offer new applications, was an optically
scanned videodisc system. The disc is recorded as a continuous spiral
track. This track consists of a succession of 0.6pm (approx.) wide
micro -holes whose length and spacing varies in terms of modulation.
The pitch between the spirals is about 1.6µm. Upon reading, the light
beam originating from a low power laser focused onto the spinning disc
through a large aperture lens is modulated when passing through the
holes (variable diffraction). A set of photo -electric sensors located un-
derneath the transparent disc collects this modulation and changes it
into an electric signal. After demodulation, the resulting signal
reproduces the recorded video signal.
Each revolution of the disc corresponds exactly to one television
frame which permits indefinite freeze -framing (videotape can only be
held for two seconds) and, providing more than 50 copies are produced
from any one master, discs are cheaper than tapes. In addition, there is
speedy random access to any of the 45,000 frames on each disc (taking
about two seconds from selection to presentation), and the disc can be
played forwards or backwards at normal, fast or slow speeds without
any wear. The recording is made, initially, on a polished glass disc
covered with a 0.15µm -thick photo resist coating, the information be-
ing recorded on this photoresist by a modulated laser. The final, flexible
PVC videodiscs, stamped by an electroformed die, give approximately
MICROPITS ENGRAVED ON THE DISC 30 minutes continuous play, or access to 45,000 individual still pictures
OF AN OPTICAL READOUT SYSTEM in full colour.

rec C OU a selection from our postbag

Readers requiring a reply to any letter must include a stamped addressed envelope.
Opinions expressed in Readout are not necessarily endorsed by the publishers of Practical Electronics.

Cheaper Ports bus, it is likely that it would be possible to get

away with replacing £1.08 worth of CMOS
pense) or change the element every time-
could be difficult i f you only have the one iron!
rather than £12.00 worth of 74251s. Seriously though, we were not aware that
Sir-I wonder if I might, albeit somewhat J. McCarthy, 12V elements were available-nor was our
belatedly, comment on the Semiconductor Dulwich, London. contributor, who works for a large British
Update of the July '78 issue. The method equipment and component manufacturer!
suggested of obtaining eight 8 -bit ports using
eight 74251s is of course valid, but is rather WeII-er! However, our unit can be built for approx-
imately the same price as the element and is
expensive, as according to one advertiser these very much more convenient to use.
will cost a total of £12.00. A way of saving Sir-I read with interest Mr D. J. Bradbury's
around a 'fiver' with no loss of elegance is to article in the August issue concerning Weller
use 10 chips as follows; soldering irons. A few months ago I was faced
8 x 74151 exactly as described £6.48
with the same problem, namely running a 24V No oh!
iron from a 12V source. My solution is, I
2 x 4016 transmission gates £1.08 Sir-A slip of the pen seems to have gone into
think, far more elegant. It does away with DI,
D2, D3, TR1, RI, CI and C2 in Mr Brad- print in Walter Hediger's neat little pH meter
£7.56 bury's project. In fact the only component (August issue).
necessary is a 12V element part number The scale is of course logarithmic in con-
saving £4.44 HE60 (12) for the TCP I or part number HE2 cept and so "0" should not appear on it. This
All prices stated are from the same advertiser. (12) for the TCP2 iron. You must surely agree may seem a small point but since all log. based
The two 4016s are connected between the that the best circuit is always the simplest one! scales can be divided ad infinitum it is a pity to
outputs of the 74151s and the data bus and N. Goldring, spoil the effect by an error of principle.
their eight control lines are connected to Reading. Far better on log. scales to have a small
wherever the selects of the 74251 would have space then start with "1". In the case of pH a
been connected. We agree that the best circuit is the value of "0" would imply some "absolute
A further advantage, over and above that of simplest-provided it does not have any draw- acid" capable of dissolving anything-
pure cost saving, is that, if a mishap should backs! The Weller element costs f4.80 and it including the meter probe.
occur, and the databus drivers and the port is necessary to solder it in, so you must either R. E. Hurst,
controller should disagree as to who has the purchase a complete I2V iron (at greater ex- Blackpool.

1102 Practical Electronics October 1978

 LOOK! Here's how you
master electronics
the practical way This new style course will enable anyone to
have a real understanding of electronics by a
modern, practical and visual method. No
previous knowledge is required, no maths, and
an absolute minimum of theory.
You learn the practical way in easy steps
mastering all the essentials of your hobby or to
further your career in electronics or as a self-
employed electronics engineer.
All the training can be carried out in the
comfort of your own home and at your own
pace. A tutor is available to whom you can
write, at any time, for advice or help during
your work. A Certificate is given at the end of
every course.

1 Build an 2 Read, draw and 3 Carry out over

oscilloscope understand 40 experiments
As the first stage of your training, you
actually build your own Cathode ray
oscilloscope' This is no toy, but a test
circuit diagrams on basic circuits
In a short time you will be able to We show you how to conduct
instrument that you will need not only read and draw circuit diagrams, under- experiments on a wide variety of different
for the course's practical experiments. but stand the very fundamentals of television. circuits and turn the information gained
also later if you decide to develop your radio, computers and countless other into a working knowledge of testing,
knowledge and enter the profession. It electronic devices and their servicing servicing and maintaining all types of
remains your property and represents a procedures. electronic equipment. radio, t.v. etc
very large saving over buying a similar
piece of essential equipment.
All students enrolling in our courses receive
a free circuit board originating from a
computer and containing many different
components that can be used in experiments
and provide an excellent example of current
electronic practice.
=I NMI NEI INN =I MIN EN EN =I
To find out more about how to learn electronics in a new, exciting and absorbing way, just
clip the coupon for a free colour brochure and full details of enrolment.
British National Radio & Electronic School
P.O. Box 156, Jersey, Channel Islands
NAME
PEB10 ADDRESS
....................................................................... Block caps please
ME ENO =II EM MI
Practical Electronics October 1978
 WORLD

CANON
COMPONENTS
RADIO TV
HANDBOOK 1978
by J. M. Frost . £8.00

A PRACTI9AL--INTRO. TO ELECTBONie-r-
OFFER A FANTASTIC RANGE AT VERY CIRCUITS-by M. H. Jones Price: £4.60
THE TTL DATA BOOK FOR DESIGN
COMPETITIVE PRICES including ... ENGINEERS by Texas
THE OSCILLOSCOPE IN USE
Price: £5.65

R.F. SPEAKERS LEADS jattr Price: £2

DIGITAL CABINETS PLUGS AUDIO AMPI71FITM-FD E HOME

CONSTRUCTOR by I. R. Sinclair Price: £2.55
TRANSISTORS AMPLIFIERS JACKS
VIDEOTAPE RECORDING
LINEAR I.C.'s MICROPHONES POWER SUPPLIES by J. F. Robinson Price: £7.60
DISPLAYS MIXERS METERS IC OP -AMP COOKBOOK
by W. G. Jung Price: £10.00
LED's HEADPHONES SURPLUS ITEMS
LINEAR INTEGRATED CIRCUIT APPLICA-
RESISTORS TURNTABLES TAPES TIONS by G. B. Clayton Price: £5.30
CAPACITORS LIGHT MODULATORS RADIO's FOUNDATIONS OF WIRELESS & ELEC-
TRONICS by M. G. Scroggie Price: 14.40
HARDWARE LIGHT BOXES CALCULATORS
BEGINNER'S GUIDE TO ELECTRONICS
CHASSIS SPOTS TEST EQUIPMENT by T. L. Squires Price: £2.55
BOXES BULBS KITS THE RADIO AMATEUR'S HANDBOOK 1978
JINGLE MACHINES VERO BOARD by A,R.R.L. Price: £7.60
S -DEC
PRICEIETLUDE STAGE
T -DEC PACKS SOLDERING IRONS
TRANSFORMERS TWEETERS SOLDER
ACCESS OR BARCLAYCARD THE MODERN BOOK CO.
PHONE OR SEND S.A.E. FOR LISTS ACCEPTED BRITAIN'S LARGEST STOCKIST
of British and American Technical Books
19-21 PRAED STREET
322-324 WHITEHORSE ROAD CROYDON LONDON W2 INP
SURREY CRO 2LF Phone 01-723 4185
Closed Saturday p.m.I

OPEN DAILY 9.30 A.M. 6 P.M. TEL. 01-684 9872

SINCLAIR PRODUCTS. BATTERY ELIMINATORS

Microvision TV now in stock £200. PDM35 3 -way models with switched output and 4

Pi Flew PCB (Drilling iTlachine digital multimeter E27-25. Mains adaptor

E3-24. De -luxe padded case £3-25. 30kV
probe 118-36. New DM235 digital multi -
way multi -Jack:- 3/44/6V 100ma E2-92
6/7I/9V 300ma ET -30. 100ma radio
models same size as a PP9 battery with
meter £47-50. Cambridge programmable press stud connectors. 9V E2-85. 6V E2-85.
scientific calculator E 13-15. Prog. library 12- 44V E2-85. 9Vx9V E4-50. 6Vx 6V £4-50.
95. Mains adaptor 13-20. Enterprise 44./.44-V (4-50. cassette recorder mains
programmable calculator E20-95. unit 7-}V 100ma with 5 pin din plug 12-85.
car convertors 12V dc input. Output 9V
S-DECS AND T-DECS. 300ma E1-50. Output 74V 300ma E1-50.
S-DeC f3-39. T-DeC f4-44. u-DeCA E4-52.
ii-DeCB E6-73. 16 dil or 10T05 adaptors BATTERY ELIMINATOR KITS
with sockets E2-14. Send sae for free leaflet on range. 100ma
CONTINENTAL SPECIALITIES radio types with press stud connectors. 44-V
PRODUCTS* 11-80. 6V E1-80. 9V E1-80. 44--1-4-1V
EXP300 E6-21. EXP350 13-40. EXP600 E2-50. 4-6+6V E2-50. 9 x9V £2-so.plug cassette
E6-80. EXP650 13-89. EXP4B 12-48. P86 type 7V 100din E1-80.
f9-94. PB100 E12-74. LM1 E30-99. LP1 heavy-duty 13 wayma rtestypes 44/6/7/13-1/11/13/
f33-48. LP2 £19-44. 14/17/21/25/28/34/42V. Amo (4-65.
1

2 Amp E7-25. transistor stabilized 8 -way

TV GAMES types for low hum 3/44/6/74/9/12/15/ 18V
Send sae for free data. New racing car TV 100ma E3-20. 1 Amp E6-40. variable volt-
games chip AY -3-8603 plus economy kit age stabilized models. 2-18V 100ma
E20-60. Tank battle chip AY -3-8710 plus 13-60.2-30V lA 16-95.2-30V 2A E10-95.
economy kit f 13-95. Stunt motor cycle chip car convertors 12V dc input. Output 9V
AY -3-8760-1 plus economy kit 112-50. 10 300ma £1-50. Output 74V 300ma E1-50.
game paddle 2 chip AY -3-8600 plus econ,
omy kit 112-50. AY -3-8500 chip plus
economy kit 18-95. Modified shoot kit BI-PAK AUDIO MODULES
f4-96. Rifle kit 14-95. Colour generator Send sae for data. 5450 tuner 123-51. AL60
kit E7-50. Attractively cased, assembled TV E4-86. PA100 f16-71. SPM80 (4-47.
games:- stunt cycle 125-95, tank war game BMT80 £5-95. MK60 £38-74. Stereo 30
£39-95. 4 game models (tennis, football, E20-12.
squash, pelota/:- black and white 111-95.
colour E14-50. De -luxe 6 game Ww model BULK BUY OFFERS
with pistol attachment f 17-95. Minimum purchase E3 any mix from this
MAINS TRANSFORMERS section. IN4148 1.3p. IN4002 3.6p BC212
6-0-6V 100ma 79p, 14A £2-35. 6.3V 1-4A 8p. 741 8 dil 15p. NE555 8 dil 29p. 723
f1-89. 9-0-9V 75ma -79p, 1A E1-99, -2A 14 dil 43p. Dale pens 59p. AC76023N exact
A Printed Circuit Board Drilling Machine, suitable for production or modification of (2-60. 12-0-12V 50ma 79p, 100ma 90p, equiv. of SN76023N with improved heat
IA E2-49. 13V 4A 95p. 15-0-15V 1A sink 79p. Plastic equiv.. of popular transis-
circuit boards. The machine, by way of its kinetic design, is in fact a chuckless Drilling tors:- 8C108 3.8p, BC109 4.4p, BCY71
Machine, requiring no guide bushes for the turbo shank tungsten carbide drills. f2 -79.30-0-30V 1 E3-59. 4.7p, BCY72 4.4p, fuses 20 mm x 5 mm
JC12, JC20 AND JC40 AMPLIFIERS cartridge .25, .5, 1, 2, 3, 5 Amp. Quickblow
The drills run in vee blocks at the drill arm end and, therefore, run perfectly accurately a: A range of integrated circuit audio amplifiers type 0:7p. Antisurge type 3.4p. resistors 5%
speeds of 15,000 r.p.m. supplied with free data and printed circuits l2 10 ohm to 10M. IAN 0.8p. 1W 1.9p.
JC12 6 watts 1-60. JC20 10 watts E2-95. ,polyester capacitors 250V .01, .022. .033,
JC40 20 watts E4-20. Send sae for free data p .015mf 1.1p, .0613mf 1.4p,
* REAR OF MACHINE LIFTS FOR on our range of matching power and preamp 0.1rnf 1.5p. 0.22mf 3p. 0.33mf 2.5p, 0.47mf
* FAST WORK THROUGHPUT kits. 4.8p. polystyrene capacitors E12 63V 15 to
* INTEGRAL VACUUM ATTACHMENT CIRCUIT MODIFICATIONS 6800pf 24-p. ceramic capacitors 50V E12
* ADJUSTING SCREW TO FACILITATE FERRANTI ZN414 22pf to 1000pf 1.7p. E6 1500 to 33000pf
FOR SWARF DISPERSAL IC radio chip E1-05. Extra pans and pcb for
TR ACK CUTTING 1.7p. 47000pf 2p. electrolytic. 50V .47, 1.
* FULLY ADJUSTABLE BACK STOP radio 13-85. Case £1. Send sae for free data. 2mf 5p. 25V 5mf 5p. 1 Omf 4p. 18V 22mf
AND SIDE GAUGE *0.2rnrn - 2mm DRILLS PRINTED CIRCUIT MATERIALS 5p. 33. 47. 100mf 6p. 220, 330mf Op.
PC etching kits:- economy £1-70, standard 470mf 11p. 1000mf 12p. toners 400mW
E3-82. 50 sq ins pcb 40p. 1 lb FeCI E1-05. E24 2V7 to 33V 6.1p. preset pots sub
Etch resist pens:- economy 45p, dale 73p. miniature 0.1W horiz. or vert. 100 to 4M7
Made in England by Trade and Export Enquiries Welcome Small drill bits ins or 1 mm 20p each. 6.8p. potentiometers 4K7 to 2M2 log
Etching dish 68p. emulate cutter 75p. or lin. single 26p. dual 76p.
Cash with Order add £2.00 P.P and VAT
brian GEORGE SWAN LEY ELECTRONICS
ENGINEERING BARCLAYCARD Barclaycard or
Access Quote DEPT. P.E., 32 Goldsel Rd., Swanley, Kent BR8 8E2
(Cambridge)LTD Name d., &
Ca, Number Mail order only. Please add 30p to the total cost of order for postage. Prices include VAT.Overseas
MERCERS ROW. CAMBRIDGE 57744 customers deduct 7% on items marked and 11% on others. Official credit orders welcome.

Practical Electronics October 1978

1104
 TUAC
TRANSISTOR UNIVERSAL AMPLIFICATION CO. LTD.
PHONE 01-672 3137/672 9080
MANUFACTURERS OF QUALITY AMPLIFICATION AND LIGHTING
PRICES INCLUDE VAT. P & P FREE
correct at 1.8.78
TO ORDER BY POST
Make cheques/P.O.s payable to TUAC LTD. (PE108) or quote
Access/Barclaycard No. and post to TUAC LTD. IPE1081 119
Charimont Road, London SW17 9A8. We accept phone orders
from Access/Barclaycard Holders. Phone 01-672 9080.
CONTROL SYSTEMS

AMPLIFIER MODULES
NEW FROM TUAC
ULTRA QUALITY HIGH POWER
New D.C. Coupled Design
AMPLIFIERS SPEC. INPUT
Featuring SENSITIVITY 60 mV
Electronic Short Open & Thermal Overload Protection. for full output
Brief Spec. Frequency response
Input Sensitivity 0.775.v. R.M.S. 10.1).B.) at 25 K Ohms 20 Hz -20 KHz
Frequency Response 20 Hz -20 KHz HUM & NOISE-7OdB
Hum & Noise - 100 dB Relative full output
T. H.D. at full power 0.1%
TL30 5" x 5" x 2"
T.D. 500 300W into 2 Ohms 35 watt 10 amp output transistors £13.25
220W into 4 Ohms
140W into 8 Ohms £45.00 71.60 5" x 5" x 3"
60 watt R.M.S. continuous sine wave output
Power supply P.S. 300 £30.00 2 R.C.A. 110 watt 15 amp outpout transistors £18.50
T.D. 150 150W into 4 Ohms
100W into Ohms £26.25 TL100 5'x 5" x
100 watt R.M.S. continuous sine wave output
Power supply P.S. 150 £1 8.50 2 R.C.A. 150 watt 15 amp output transistors £21.50
T.D. 150. 60 Version 60W into 8 Ohms
40W into 15 Ohms. £17.75 TO TP125 7" x 61- 3"
125 watt R.M.S. continuous sine wave output
Power supply P.S.60 £15.50 x 5"x 2" 150 4 R.C.A. 150 watt 15 amp output transistors £27.50
Note P.S. 300 will drive 2 T.D. 150 amplifiers All output ratings are R.M.S. continuous sine wave output.

4 CHANNEL SOUND 3 CHANNEL

TO LIGHT LIGHT MODULATOR
SEQUENCE CHASER SILMB
- 4LSMI
Full wave control RCA BA Triacs
RCA 8A Triacs 1000W per channel
1000W per channel Each channel fully suppressed
Fully supressed and fused STEREO DISCO MIXER and fused
Switched master control for sound With touch sensitive switching and auto fade Master control to operate from
operation from 1-1N to 125W INPUTS: Four identical stereo inputs available with any equalisation. Two magnetic and two flat supplied as 1W to 125W
Speed control for fixed rate standard. High quality slider control on each channel Volume, treble and bass controls for each pair of sliders. Full wave control
sequence from 8 per minute Sensitivity mug_ 3mV IR. I A A. comp I Flat 50mV at 1kHz. Bass controls t 18dB at 60Hz Treble controls ±18d13 at
to 50 per second 15kHz
OUTPUT: 11p to 3 volts (.) 12dB) available. Attenuated output for TUAC Power Modules Rotary master and
£20.75
Full logic integrated circuitry with balance controls Band width 15Hz - 25kliz t dB.
optical isolation for amplifier P.F.L.: Output 250mV into 8 ohms. Rotary volume control. Monitoring facility for all 4 channels. Selection via
protection Single Channel Version 1500 Watts
touch sensitive illuminated switches. Switched visual cue indicator.
£21.50 Miscellaneous Facilities: Two illuminated deck on/off switches. Mains illuminated on/off switches Auto fade
illuminated on/off switch. Mains powered with integral screen and back cover. Complete with full instructions
£9.75
Sum 25in long 6in high x 3m deep
Model 501 500W per channel as
above without sound triggering Mono Disco Mixer with autofade £49.00
£149.00
£14.00
POWER
SUPPLIES

Vacuum varnish impregnated. Transformers ADD SEQUENCE CHASING +

FRONT PANEL FOR LIGHTING with supply board incorporating pre -amp supply:
EFFECT MODULES DIMMING EFFECTS FOR
PS250 for supplying 2 TP125s £30.00
(complete with switches, neons and knobs) PS200 for supplying to TL100s £30.00 TUAC 3 CHANNEL LIGHT
as illustrated PS60/60 for supplying 2 TL6Os £30.00
PS125 ± 45 volts for TP125 £18.50 MODULATOR
PS100 ± 43 volts for TL100 £17.00
PS60 ± 38 volts for TL60 £15.50
PS30 ± 25 volts for TL30 £11.75

\k`"
PS U 2 for supplying disco mixer £7.50 lig oleo
For si !Ana £7.25 4LSM1 £6.00 STOCKISTS - CALLERS ONLY
Size 8" x 41/2" Size 61/2" x 41/2"
Al Music. 88. Oxford Street, Manchester (Tel 061-236 0340)

II
Geo Mathews. 85/87. Hurst Street. Birmingham (Tel 021-622 1941)
Soccodi, 9. The Friars (Tel Canterbury 609481
Cookies Disco Centre. 126 128, West Street (Tel Crewe 47391
Garland Bros. Ltd., Deptford Broadway. London 01.692 4412 Speed Control 3 per min. to 10 per sec.
Luton Disco Centre. 88, Wellington Street. Luton (Tel Luton 4117331 Full logic integrated circuitry
Dimmer control to each channel
S1LMB £8.25 Session Music, 163, Mitcham Road, Tooting (Tel 01-672 34131.
FUZZ LIGHTS Combined with 3SDM 1 Mon -Set 10ann to 6pm. Closed Wed.
Red, Green, Blue, Size 9" x 4+" 3SDMI £15.25
Amber. £24.50 TRADE & EXPORT ENQUIRIES 01-672 3137
SUPPLIERS TO H.M. GOVT. DEPTS. MANUFACTURED AND ASSEMBLED IN GT. BRITAIN FULLY TESTED AND GUARANTEED
SEND NOW FOR OUR FREE 28 PAGE ILLUSTRATED CATALOGUE. SEND STAMP PLEASE

1105
Practical Electronics October 1978
 100 PIV 25 Amp S.C.R's Branded for 40p.
100 PIV 10 Amp BRANDED DIODES (v. 15p each.
3 PIN PLUG AND SOCKET like RS European type with 2 metres of Cable. 76p pr.
1 of 25v.w. ELECTROLYTIC CAPACITORS 6 for 25p.
MULLARD PRE -AMPLIFIER I.C. TYPE TAA 435 40p.
SUB -MINIATURE TANTALUM CAPACITOR. 4.7uf 10v.w. 4 6 for 25p.
6 WATT WIRE WOUND POTENTIOMETERS 1.2K 4 22p each.
0.2" LED's Red (9 15p, Green 0 18p.
ITT CAPACITORS TYPE PMT -2R Miniature 1 of 1 00v.w. N, 20p doz.
DISC CERAMICS -.tuf 18v.w. (a 25p doz.
5 TURN POTENTIOMETERS 5K 0 £1, TEN TURN 1K. 5K. 100K 4 £1.50.
400mW UNMARKED GOOD ZENERS 3.6v. 6.8v. 10v, 11v, 12v, 13v, 16v. 24v. 30v,
33v, 36v. All at 10 for 40p.
GENERAL PURPOSE FETS Eli 1 (a 12p, 5 for 50p, E112 10p. 5 for 45p,
E113 @ 12p, 5 for 50p, E174 (a, 22p, 5 for 85p, VHF J310 @ 20p.
200 ASSORTED 1,i WATT RESISTORS for 75p.
50.2 WATT ZENERS Assorted untested for 57p.
ICS have IS44 SILICON DIODES at 25p doz
10 ASSORTED MULTI TURN PRE-SET POTENTIOMETERS 60p.
helped thousai:da 100 ASSORTED MULLARD C280 CAPACITORS for 57p.
001 of ambitious people TBA 1205 FM I.C's Untested with data. 6 for 60p.
MULLARD ELECTROLYTICS 2240uf 40v.w. 0 40p, 4500uf 25v.w. 4 40p.
to move up Into higher paid 5000uf 10v.w. @ 15p, 6400uf 25v.w. 4 25p.
more secure jobs in the field of SUB -MINIATURE B OHM LOUDSPEAKERS 1 ("din (y 75p.
12 X BAND VARACTOR DIODES for Et.
electronics -now it can be your turn. X BAND GUNN DIODES with data (a £1.65 each.
Whether you are a newcomer to the field ILLUMINATED EDGEWISE 200uA METERS at £1.25 each.
DIE CAST BOXES 4" x 2" x 1" (a 55p. 44" x 2,1," x 1i" 65p,
or already working in the industry. ICS can 41" x 2"." x 1A" N 85p, 6" x 34" x 2" 0_/. E1.15.
provide you with the specialised training so essential 60 ASSORTED WIRE WOUND RESISTORS I to 10 van S7p.
to success MINIATURE ROTARY SWITCHES 2 Pole 4 way 4 20p.
50. BC 107-8-9 TRANSISTORS Untested (0 57p.
50. AC 128 TRANSISTORS Branded but untested @ 57p.
ERIE RED CAP .01uf 100v.w. CAPACITORS (a. 5p each.
1 Amp TRANSISTORS PNP BCX36 @ 12p, BCX37 @ 10p.
Personal Tuition and Guaranteed Success 100 ASSORTED DISC CERAMICS for 57p.
30 10XAJ CRYSTALS Assorted between 5100 to 7900KHz kt £1.10.
5 WATT NPN DARLINGTON TRANSISTORS N. 20p, 3 for 50p.
CLOCK P.C. BOARDS with Buzzer. Mercury Switch, Bridge Rectifier. Transistors et,.
No data £1.
MEDIUM POWER TRANSISTORS MP 8112 kt. 15p, MP 8512 4 15p.
MOS LEVEL SENSOR TAA 320A with data 0 35p.
The expert and personal guidance by fully qualified 20 PHOTO TRANSISTORS DARLINGTONS Untested for £1.
MCMURDO 8 PIN PLUGS Vz 20p, 8 Pin Sockets @ 20p, Covers C 15P.
tutors, backed by the ICS guarantee of tuition until NKT 214 TRANSISTORS equivalent to OC 71 @ 10p. 6 for 50p.
successful, is the key to our outstanding record in the MAINS TRANSFORMERS 240 volt input Type 1.22-0-22 volt 500mA (g. £1.60
(P&P 25p/. Type 2.24 volt Tapped at 14 volt 1 amp (g. £1.30 (P&P 25p(.
technical training field. You study at the time and pace Type 3. 50 volt 10 amp @ £5.50 IP&P 95p1, Type 4. 50 volt 2 amp,
tbat suits you best and in your own home. In the words 45 volt 500mA @ £3.50 (P&P 85p1, Type 5. 20 volt 1 amp Twice, 10 volt 1 amp
twice kr £4.50 (P&P 95p(.
of one of our many successful students: "Since starting 2200uf 100v.w. 0 60p, 100uf 100v.w. @ 6 for 25p. 4700uf 63v.w. @ 50p.
3300uf 63v.w. @ 50p. ELECTROLYTICS.
my course, my salary has trebled and I am expecting a 2 GHz STRIPLINE NPN TRANSISTORS N f1 each.
further increase when my course is completed."
Please add 20p for post and packing, unless otherwise stated, on U.K. orders under £2
Overseas orders at cost.

City and Guilds Certificates

J. BIR KETT
RADIO COMPONENT SUPPLIES
Excellent job prospects await those who hold one of these 25 The Strait, Lincoln LN2 1JF Tel. 20767
recognised certificates. ICS can coach you for:
Telecommunications Technicians
Radio, T.V. Electronics Technicians
Technical Communications
Radio Servicing Theory
Radio Amateurs
Electrical Installation Work
Also MPT Radio Communications Certificate

COMPONENTS - Now over 1,000 types in stock.

Diploma Courses K ITS - See the new range of low-cost 'ELEK ITS'.
MODULES - New ready -built functions,
SERVICE - 1st Class same day despatch.
QUALITY - All guaranteed products. LOG
ACE MAILTRONIX 00
Colour T.V. Servicing Dept PE isolal Strut
PRICES - Many reductions!
Electronic Engineering & Maintenance MAGAZINE PROJECTS - Trouble -free!
Wakefield W Yorkshire MI 5.111
Computer Engineering and Programming
Radio, T.V. and Audio, Engineering & Servicing Our 2n edition illustrated catalogue is now available.
Electrical Engineering, Installations & Contracting
The much increased range shows many welcome
reductions.
INTRODUCING The new range of easy build kits com-
Other Career Courses plete with simple to follow instructions.
FABULOUS Battery powered (not supplied). With case.
* BURGLAR ALARM *ROULETTE
A wide range of other technical and professional courses
are available including GCE.
ILEKITS
Easy build introduc-
* BICYCLE SOUND FLASHER
*WATER LEVEL ALARM *SIREN
tion to electronics. *BLINKER *TIME SWITCH
Many hours of enjoy- Many others in preparation - included
ment. in full ACE catalogue - send S.A.E. for
Post this coupon or 'phone today for free NOW AVAILABLE! free brochure of kit range.
ICS careers guide.
ORGY
Mini ORGAN
MORSE
only \ TRr!E 11,,,-Ailr
Address
E795 Only , ,
ic.
,

Ell ID
Age
4Fezzer. A
;eek PRICES
,
41
To ICS, Dept. 273Z , Inter -text House,
London SW8 4UJ
ktvgiir, -.41..... J..

or telephone 01-622 9911 (all hours) I enclose 30p*, please send catalogue.
Name
Address
Refundable with future orders over £5.00.

Practical Electronics October 1978

 15-240
HY5
WATTS! The HY5 is a mono hybrid amplifier ideally suited for all applications. All common
input functions (mag Cartridge, tuner, etc.) are catered for internally, the desired
function is achieved either by a multi -way switch or direct connection to the
appropiate pins. The internal volume and tone circuits merely require connecting
Preamplifier to external potentiometers (not included). The HY5 is compatible with all I.L.P.
power amplifiers and power supplies. To ease construction and mounting a P.C.
connector is supplied with each pre -amplifier.
FEATURES: complete pre -amplifier in single pack. multi -function equalisation. low noise. low
distortion, high overload. two simply combined for stereo.
APPLICATIONS: hi-fi. mixers. disco: guitar and organ: public address.
SPECIFICATION: Inputs -magnetic pick-up 3mV: ceramic pick-up 30mV. tuner 100mV. microphone
10mV. auxiliary 3-100mV. input impedance 47kfl at 1kHz. Outputs -tape 100mV. main output 500mV
R M.S Active Tone Controls -treble x 12dB at 10kHz. bass 12dB at 100Hz. Distortion -0 1%
at 1kHz. signal/noise ratio 68dB. Overload-38dB on magnetic pick-up. Supply Voltage- ± 16-50V.
Price £6.27 + 78p VAT. P.& P. free
HY5 mounting board B.1. 48p + 6p VAT. P. & P. free
The HY30 is an exciting New kit from I.L.P. It features a virtually indestructible
HY30 I.C. with short circuit and thermal protection. The ,kit consists of: I.C.. heatsink,
P.C. board. 4 resistors, 6 capacitors, mounting kit, together with easy to follow
15W into sn construction and operating instructions. This amplifier is ideally suited to the
beginner in audio who wishes to use the most up to date technology available.
FEATURES: complete kit: low distortion. short, open and thermal protection. easy to build
APPLICATIONS: updating audio equipment. guitar practice amplifier, test amplifier. audio oscillator
SPECIFICATION: Output Power -15W R.M.S. into en. Distortion -0-1% at 15W. Input Sensitivity-
500mV Frequency Response-10Hz-16kHz -3dB.
Price £6.27 + 78p VAT. P. & P. free
The HY50 leads I.L.P.'s total integration approach to power amplifier design.
HY50 The amplifier features an integral heatsink together with the simplicity of no external
components. During the past three years the amplifier has been refined to the extent
that it must be one of the most reliable and robust High Fidelity modules in the World.
25W into Ein FEATURES: low distortion. integral heatsink. only five connections. 7 amp output transistors. no
external components.
APPLICATIONS: medium power hi-fi systems. low power disco. guitar amplifier.
SPECIFICATION: Input Sensitivity-500mV Output Power -25W R.M.S. into en. Load Impedance -
4 -16n. Distortion -0 04% at 25W at 1kHz. Signal Noise Ratio-75dB. Frequency Response-l0Hz-
45kHz - 3dB. Supply Voltage- rt 25V. Size -105 x 50 x 25mm
Price £8.18 + £1.02 VAT. P. & P. free
The HY120 is the baby of I.L.P. s new high power range. designed to meet the most
HY120 exacting requirements including load line and thermal protection this amplifier sets
a new standard in modular design.
FEATURES: very low distortion integral heatsink load line protection thermal protection five
60W into connections. no external components.
APPLICATIONS: hi -ti. high quality disco. public address. monitor amplifier. guitar and organ
SPECIFICATION: Input Sensitivity-500mV. Output Power --60W R.M.S. into 8C1 Load Impedance
4-16n. Distortions -04% at 60W at 1kHz. Signal Noise Ratio-90dB. Frequency Response-lOHz-
45kHz -3dB.Supply Voltage- rt. 35V Size -114. 50 x 85mm
Price £19.01 + £1.52 VAT. P. & P. free
The HY200 (now improved to give an output of 120 watts) has been designed to
HY200 stand the most rugged conditions such as disco or group while still retaining true
hi-fi performance.
FEATURES: thermal shutdown very low distortion load line protection. integral heatsink. no external
120W into sn components.
APPLICATIONS: hi-fi. disco. monitor. power slave. industrial, public address.
SPECIFICATION: Input Sensitivity-500mV Output Power -120W R.M.S. into 811 Load Impedance -
4 -16n. Distortion -0 05% at 100W at 1kHz. Signal Noise Ratio-96dB Frequency Response-10Hz-
45kHz - 3dB. Supply Voltage- ± 45V. Size -114 x 50 x 85mm.
Price £27.99 + £2.24 VAT. P. & P. free
The HY400 is I.L.P.'s Big Daddy of the range producing 240W into 4f11 It has been

HY400 designed for high power disco or public address applications. If the amplifier is to
be used at continuous high power levels a cooling fan is recommended. The amplifier
includes all the qualities of the rest of the family to lead the market as a true high
240W into 41 power hi -fidelity power module.
FEATURES: thermal shutdown, very low distortion: load line protection. no external components.
APPLICATIONS: public address. disco, power slave. industrial
SPECIFICATION: Output Power -240W R.M.S. into an Load Impedance -4-16n. Distortion -0 1%
at 240W at 1kHz. Signal Noise Ratio-94r1B. Frequency Response-lOHz-45kHz - 3dB. Supply Voltage
- 45V. Input Sensitivity-500mV. Size -114 x 100 x 85mm
Price £38.61 + £3.09 VAT. P. & P. free
POWER SUPPLIES: PSU38-suitable for two HY3Os £8.44 + 81p VAT. P. & P. free. PSU50-suitable for two HY5Os £8.18 + £1.02
VAT. P. & P. free. PSU70-suitable for two HY120s £14.58 + £1.17 VAT. P. & P. free. PSU90-suitable for one HY200 £15.19 + £1.21
VAT. P. & P. free. PSU180-suitable for two HY200s or one HY400 £25.42 + £2.03. VAT. P. & P. free.
Free post + packing applicable to U.K. only.

TWO YEARS' G UARANTEE ON ALL OUR PRODUCTS

Please supply
I.L.P. Electronics Ltd. Total Purchase price
I Enclose: Cheque El Postal Orders 0 Money Order 0
Crossland House, Please debit my Access account 0 Barclaycard account 0
Nackington, Canterbury Account number
Name and Address
Kent CT4 7AD
Tel (0227) 63218
Registered office No 1032530 Signature

Practical Electronics October 1978

SUPERSOUND 13 HI-FI MONO MAINS OPERATED SOLID STATE HARVERSONIC SUPERSOUND
AMPLIFIER AM/FM STEREO TUNER 10 + 10 STEREO AMPLIFIER KIT
200 240V Mains operated A really first-class Hi-Fi Stereo Amplifier Kit. Uses 14 transistors
A superb solid state audio amp- Solid State F.M A.M Stereo
lifier. Brand new components including Silicon Transistors in the first five stages on each
- Tuner Covering M.W A.M channel resulting in even lower noise level with improved
0 1 throughout 5 silicon Pan- ...---...________--,s0----
-- 540-1605KHz VHF F.M
stators plus 2 power senitiiy. Integral pre -amp with Bass. Treble and two Volume
1, ;,-. i
. 'Pill.
hilw output transistors in
push-pull Full wave
- 88-108MHz
Built-in Ferrite rod aerial for
controls. Suitable for use with Ceramic or Crystal cartridges. Very
simple to modify to suit magnetic cartridge -instructions included
-
111 M.W Full AFC and AGC on Output stage for any speakers from 8 to 15 ohms. Compact design
li Di. ',. rectification. Output __---- =

A.M and F M. Stereo Beacon

-- - -
approx. 13 watts r.m.s. 116 . all parts supplied including drilled metalwork. high quality ready
Lamp Indicator. Built mere- drilled circuit board with component identification clearly
into 8 ohms. Frequency amps with vanable output
response 12Hz 30KHz marked, smart brushed anodised aluminium front panel with
'19 voltage adjustable by pre-set matching knobs, wire. solder, nuts. bolts -no extras to buy
n 3db. Fully integrated contro Max cop Voltage 600mV R.M S. into 20K. Simulated Teak
pre -amplifier stage with sop- Simple step by step instrucfions enable any constructor to build an
finish cabinet. Will match almost any amplifier Size aiin wide ii amplifier to be proud of. Brief specification, Power output 14 watts
aisle Volume. Bass boost and 4in high - 9lin deep approx.
Treble cut controls. Suitable for R.M S per channel into 5 ohms Frequency response -I-3dB
8-15 ohm speakers. Input for ceramic or crystal cartridge. Limited number only at £2800 + £1 .50 P. & P. 12-30.000Hz. Sensitivity better than 80mV into 1 MG Full power
Sensitivity approx. 40mV for full output Supplied ready built and bandwidth I 3dB 12-15.000Hz. Bass boost approx to n12dB
tested. with knobs, escutcheon panel, input and output plugs. MAINS TRANSFORMER. PRI. 0.110 and 240. SEC. 28V at Treble cut approx to -16d61. Negative feedback 18dB over main
Overall size Sin high . 6in wide . 7,tri deep. AC 206250V 1.8 amps. Also tapped at 12V .3 amp. Overall size 2 rh x 31-"w x amp. Power requirements 35V at 1A.
PRICE 05.00 P &P £1 20 21"d. 82-50 -I- P&P C1-00. Overall size l2in wide x Bin deep x 2 lin high.
Fully detailed 7 page construction manual and parts list free with
kit or send 25p plus large S AE
HARVERSONIC MODEL P.A. 10/14 WATT HI-FI AMPLIFIER KIT
TWO ZERO
An advanced solid state general 1
1 dr iia
- A stylishly finished monaural amplifier with an output of 14 watts
from 2 EL84s in push-pull. Super reproduction of both music
and speech, with negligible hum. Separate inputs for mike and
gram allow records and announcements to follow each other.
AMPLIFIER KIT
(Magnetic input components 33p extra)
POWER PACK KIT
£13.50 P & P. 80p

£5.50 P. & P. 95p

purpose mono amplifier suitable 0 -. .. . CABINET £5 - 50 P. & P. 95p
for Public Address system, Dram Fully shrouded section wound output transformer to match SPECIAL OFFER -only E23.25 If all 3 Item.
Guitar, Gram.. etc Features 3 3-150 speaker and 2 independent volume controls, and separate ordered at one time plus tl i25 P. 8 P.
Individually controlled inputs teach bass and treble controls are provided giving good lift and cut.
Yak. line-up. 2 EL84s ECC8 3 EFB6 and E280 rectifier. Simple Fun after sales service
input has a separate 2 stage -erne pre). Input 1, 1 SmV into 47k. Also available ready built and tested DT 25 P. & P £1 50
Input 2, 1 5mV into 47k (suitable for use with mic. or guitar etc.). klet 25P + S.A.E. (Free with pans). All parts sold
instruction booklet
Input 3, 200mV into 1 meg. suitable for gram, tuner, or tape etc. separately. ONLY E14.50 P. & P. E140. Also available ready
Fun mixing facilities with null range bass 5 treble controls. All built and tested £19.00 P. & P. El -40. HARVERSONIC STEREO 44
inputs plug into standard jack sockets on front panel. Output A solid state stereo amplifier chassis. with an output of 3-d watts
socket on rear of chassis for an 8 ohm or 16 ohm speaker RANGE
par channel into 8 ohm speakers. Using the latest high technology
Output in excess or 20 watts R M S. Very attractively finished ECRO-DYNAMIC
"POLYY SPEAKER WIDE
PLANARWAFER-TYPE, integrated circuit amplifiers with built in short term thermal
purpose built cabinet made from black vinyl covered steel, with a Size 1 lin x 1 411in x 14in deep. Weight 1 9oz. Power handling overload protection. All components including rectifier smoothing
brushed anodised aluminium front escutcheon For ac mains 20W R.M.S. 140W peak). Impedance 8 ohm only. Response capacitor, fuse, tone control. volume controls. 2 pin din speaker
operation 200240 volts Size approx 12) -in wide -. 5th high r 40Hz-20KHz. Can be mounted on ceilings, walls, doors, under sockets and 5 pin din tape rec play socket are mounted on the
7,in deep tables. etc. and used with or without baffle. Send S.A.E. for printed circuit panel. Size approx 9,in . 21in , tin max depth
Special introductory price En '00 - £2 50 carriage and full details. Only £8.40 each + P. & P. lone 610p, two E1101. Now Supplied brand new and tested. with knobs. brushed anodised
packing. available in either Bin round version or el i x 81in rectangular. 10 aluminium 2 way escutcheon (to allow the amplifier to be mounted
watts R.M.S. 60Hz-20KHz £5.25 + P. & P. (one B5p, two 759.1. horizontally or vertically) at only 29.00 - 50p P & P Mains
Millard LP1 1 59 RF-IF module 470 kHz 8215 + P & P 20p. transformer with an output of 17V a.c. at 500m. A can be supplied
Full specification and connection details supplied. MAGNETC PRE -AMP Lens. 3mV in for 100mV out. 15 to 35V at E1.50 - 40p P & P. if required. Full connection details
Pye VHF FM Tuner Head covering 8 8-1 08 MHz 10.7 MHz I.F. neg. earth. Equ. +1dB from 20Hz to 20KHz. Input impedance
output. 7-8V + earth. Supplied pre -aligned, with full circuit supplied
diagram with precision -geared F.M. gang and 32 3PF + 3 2 3PF 47K. Size llin x 21in x 5Iin H. £2410 +20p. P. & P.
A.M. Tuning gang only £3.15 + P. & P. 35p. 2in PLASTIC CONE HF TWEETER 4 ohm. STEREO DECODER
£3.50 per matched pair + 50p P. & P. SIZE 2" 3" . y ready built. Pre -aligned and tested for 9-16V neg.
STILL AVAILABLE earth operation. Can be fitted to almost any FM VHF radio or tuner.
HA34 3 Valve Audio Amp. 41w o/p. Ready built end tested £8.80 HIGH POWER HI-FI 8 ohm Dome Tweeter. 1M voice coil. Stereo beacon light can be fitted if required. Full details and
£1.40 P. & P. instructions (inclusive of hints and tips) supplied. E6.00 plus 20p
Also HSL 'Four' Amp. Similar to above but in kit form. £8.00 Magnet size 3in dia. Suitable for use in up to 50 watt systems.
.

£4.50 each 60p P. & P. P. & P. Stereo beacon light if required 40p extra.
E1.40 P.8 P.
Open 9.30-5.30 Monday to (Please write clearly)
Friday. 9.30-5 Saturday HARVERSON SURPLUS CO. LTD.
Closed Wednesday. PLEASE NOTE: P. 8 P. CHARGES
Prices and specifications correct (Dept. P.E.) 170 MERTON HIGH ST., MERTON, LONDON, S.W.19 Tel: 01-540 3985 OUOTED APPLY To U.K. ONLY
at time of press. Subject to P. & P. ON OVERSEAS ORDERS
A few minutes from South Wimbledon Tube Station
ta
CHARGED EXTRA.
alteration without notice

NO DISCO SYSTEM IS Clef Products

COMPLETE WITHOUT... P. E. JOANNA
rok-"-riki ROPEL_IGHTS Ropelight kits now available from
Roger Squire's -22 beet long, 4 channel, including Tube,
&
Price when new £39.00
} Bulbs and Multipin connectors. These ropelights are
ex -demonstration stock and will require some bulb
'STRING ENSEMBLE'
OUR PRICE ONLY £16.20 replacement - we will supply 20 spare bulbs free with your
IP8P Cl 00 each) Please note ropelight kit Additional sets of 20 bulbs cost £4 86 each
kits are available only by Mail Order

PIEZO HORNS BULGIN OCTAL PLUGS

Send S.A.E. for details of Kits & P.C.B.s
FANTASTIC SPECIAL OFFER
TO READERS OF PRACTICAL
AND SOCKETS Please indicate which instrument required.
ELECTRONICS
There's always hundreds of Bulgin
Octal multiway plugs and sockets in stock at
Tweeters for your disco. PA
system or Hi'Fi, Frequency range 56.206 Roger Squire's. Each pin rated BA Perfect for
No X over required. They can be used in your Sound to Light System. P552 SOCKET
£0.65 (P&P 35p1 P551 PLUG £1.84 PAP 35p1
16 Mayfield Road, Bramhall, Cheshire SK7 1 JU
any PA system up to 100W Why pay more/
OUR PRICE ONLY £4.99 each IP&P 35p each) Carriage on 10 or more nominal E 1.00 Also available
6 -way multicore cable 16 Amps per corel ex stock
£0.65 per metre Please phone for carriage quote
PROJECTORS
SQUIRE MULTIFECT 150 SOLAR 250 TRANSISTORS DIODES DIGITAL I.C' wAv RESISTORS
- including rotator and effects Utilising a 250W Device 10 100 Demo 10 100 Device 10 100
OFF 4.00
TEXAS 6.50
wheel. A truly versatile projector Quartz -Iodine bulb ACY 20 3.20 27.00 AA 119 60
Device
2.5W Axial 90
which uses a powerful 150W giving brilliant ASY 68 .90 6560 BY 127 90 800 A'n" OW Radial 80 610
Tungsten bulb, all effects light output, this BC 107 80 7.00 10 44 45 360 101N Axial BO 6.00
74L04
projector is fan - 'BE 118 1.10 9.00 IS 940 40 2.50 4:9, 15W Radial 85 6.00
attachments simply slot in ready for use 74L73
BC 132 .95 8.00 1S 941 40 2.50
A BARGAIN AT £40.50 1P&P £1 001 cooled and can be used
BC 147 10 6.50
74L74 4.30 BARGAIN PAKS
free standing or ceiling mounted. 74L9I 14.50 ALL ITEMS NEW& MARKED
13C 149 so 6.50 LINEAR I.C!s

PLUS MANY DISCO ACCESSORIES

Dual effect system for stunning versatility
Rotators are extra. Huge choice of special
EIC 2048
BC 348
/0
180
660 DeMce
8.00 741 1311 OIL .18
26
1

1.70
10 FAIRCHILD
Device
,. PAK 1
100 Gen. Purpose Transistors
includina BC 149. 2N 3703.
All Roger Squire's shops have a effects and attachments!' Now ONLY BC 351 1.00 7.50 555 BP OIL 2.40 9000 ,5-90 etc. mail
80 131 3.30 29.00 9002
service department which carries large £70.20 HORIZ. PRESET 422 PAK 2
BO 695A 5.50 42.00 9016 3.60 20 Transistors including
stocks of DISCO SPARES & ACCESSORIES. IP&P £2.001 80 696A 560 42.00 Device 10
9304 L.,..1 BD 131,BO 695A, etc f5.50.
For example. Fane and H H Disco Speakers BF 185 2.40 20e0 *1 Megohrn 0 25W. 80 9308 PAK 3
12" and 15" BSR and Garrard decks Plus sockets, Fuses, BF 324 330 29.00 9309
87 106 10.00 7260 CAPACITORS 10.00 100 Mixed WAN Resistors in-
at discount prices Plugs, etc etc. 100 9311
'BD 205 14.00 11560 Device
10 21,00chiding 2.5W.5W 1 OW etc
.50 3.50 n.i3,1.8
1600 12e00 0.01/25 Disc
611 208
0.01/30 Disc 55 3.50 ..1,21
,
12i00 PAK 4

Roger Squire) DISCO GEAR ZTX 2128 1.10 600 0.1/200 Radial 30 5.50 .)),-,17 111.11. 100 off 74 Series with Pre-
ITX 302 1.00 8.00
0.1/500 Axial .60 4.00 01 fanned Pins including 1410,
ZTX 502 1.10 9.00 5.50 931
0.68/100 Radial .70 7430. etc [4.00.
2N 930 360 1260 22/100 Radial 80 6.00 n.32 tr. PAK 5
2N 2647 8.00 60.00 139/6 Tent .90 7.00 .4...! 100 Gen. Purpose Diodes
Send Mail Orders to- Roger Squire's Mail Orders, Barnet Trading Estate, Park Road, Barnet, Herts. EN5 5SA 214 3103 .80 6.50 3.00
100/250 Axial 320 24.00 including IS 44. IS 941, etc.
01441 3527 Iliotlinel 01-441 1919 ISwitchboard) Open: Mon -Fri, 9-5.30. 2N 3705 60 6.50 680/25 Axial 1.60 14.00 .1m3 7.00 £2.50.
Personal callers: ROGER SQUIRE'S DISCO CENTRES Min. Order 82.00, P. & P. 30p. VAT please add 8% except those marked which are 12.5%.
LONDON 176 Junction Road, Tufnell Park, 019 500. 01-272 7474 Open from 10-5 Tues-Sat Export, Wholesale and Manufacturers Enquiries Welcome.
BRISTOL: 125 Church Road, Redfield, Bristol BS5 9JR. 0272 550550 10-8 Weds.
K & A DISTRIBUTORS
MANCHESTER: 251 Deansgate, Manchester M3 4EN. 061-831 7676 Closed Mondays
52 Barkby Road, Syston. Leicester LE7 8AF. Tel. 0533 809391.

1108 Practical Electronics October 1978

 Understanding Digital Electronics
New teach -yourself courses
Design of In the years ahead the products of digital electronics technology will
Digital Systems play an important part in your life. Calculators and digital watches are
Design of already commonplace. Tomorrow a digital display could show your
Digital Sys vehicle speed and fuel consumption; you could be calling people
Book 3 Anthmefic
C.acasts 3 by entering their name into a telephone which would automatically
look up their number and dial it for you.
These courses were written by experts in electronics and learning
systems so that you could teach yourself the theory and application of
digital logic. Learning by self -instruction has the advantages of being
faster and more thorough than classroom learning. You work at your
Design of own pace and must respond by answering questions on each new
Digital Systems piece of information before proceeding.
After completing these courses ,you will have broadened your
PC

career prospects and increased your fundamental understanding of

the rapidly changing technological world around you.

The six volumes of Design of

Digital Systems cost only: £8.10 4 90p post & packing

And the four volumes of

Design of Digital Systems is written for the engineer seeking to learn
more about digital electronics. Its six volumes - each A4 size are
Digital Computer Logic and
Electronics cost only:
£4.60 90p post & packing

packed with information, diagrams and questions designed to lead you

But if you buy both courses,
step-by-step through number systems and Boolean algebra to
memories, counters and simple arithmetic circuits, and finally to a the total cost is only: £12 El post & packing
complete understanding of the design and operation of calculators and
computers. Price includes surface mail anywhere in the world: Airmail extra.
The contents of Design of Digital Systems include:
Book 1 Octal, hexadecimal and binary number systems; conversion
between number systems; representation of negative numbers; com-
plementary systems; binary multiplication and division. Flow Charts & Algorithms
Book 2 OR and AND functions; logic gates; NOT, exclusive -OR, HELP YOU PRESENT:
NAND. NOR and exclusive -NOR functions; multiple input gates; truth safety procedures, government legislation, office proce-
tables; De Morgans Laws; canonical forms; logic conventions; Kar- dures, teaching materials and computer programs by
naugh mapping; three -state and wired logic.
means of YES and NO answers to questions.
Book 3 Half adders and full adders; subtractors; serial and parallel
adders; processors and artithmetic logic units (ALUs); multiplication THE ALGORITHM WRITER'S GUIDE explains how
and division systems. to: define the questions, put them in the best order and
Book 4 Flip flops; shift registers; asynchronous and sychronous draw the flow chart, with numerous examples shown. All
counters; ring, Johnson and exclusive -OR feedback counters; ran-
dom access memories (RAMs) and read only memories (ROMs).
that students require is an aptitude for logical thought.
Book 5 Structure of calculators; keyboard encoding; decoding display Size: A5, 130 pages. This book is a MUST for those with
data; register systems; control unit; program ROM; address decoding; things to say.
instruction sets; instruction decoding; control program structure. . + 45p post and packing by surface mail anywhere
Book 6 Central processing unit (CPU); memory organization; character £2.95 in the world. Airmail extra.
representation; program storage; address modes; input/output
systems; program interrupts; interrupt priorities; programming; assem-
blers; computers; executive programs; operating systems and time GUARANTEE
sharing. If you are not entirely satisfied your money will be refunded.
Digital Computer Digital Computer

Ele

-.
and
1.°91/4ctrodes Logic mod
Dedasida r- Cambridge Learning Enterprises, Unit 21, Rivermill Site,
FREEPOST, St. Ives, Huntingdon, Cambs. PE17 4BR, England.

8's Please send me the following books:

sets Digital Computer Logic & Electronics @ £5.50, p & p
included
sets Design of Digital Systems @ £9.00, p & p included
Digital Computer Logic and Electronics is designed for the beginner. Combined sets @ £13.00, p & p included
No mathematical knowledge other than simple arithmetic is assumed, The Algorithm Writer's guide @ £3.40, p & p included
though the student should have an aptitude for logical thought. It con- Name
sists of four volumes - each A4 size - and serves as an introduction
to the subject of digital electronics. Everyone can learn from it - Address
designer, execxutive, scientist, student, engineer.
Contents include: Binary, octal and decimal number systems; con,
version between number systems; AND, OR, NOR and NAND gates
and inverters; Boolean algebra and truth tables; De Morgans Laws; I enclose a *cheque/PO payable to Cambridge Learning Enterprises
design of logic circuits using NOR gates; R -S and J -K flip flops; binary for £
counters, shift registers and half adders. Please charge my *Access / Barclaycard /Visa /Eurocard / Mastercharge/
Interbank account number
CAMBRIDGE LEARNING ENTERPRISES. Unit 21, Rivermill Site, FREEPOST, ST. IVES, Signature *delete as appropriate.
HUNTINGDON, CAMBS. PE17 4BR, 'ENGLAND. TELEPHONE ST. IVES (0480) 67446. Telephone orders from credit card holders accepted on 0480-67446
PROPRIETORS: DRAYRIDGE LTD. REG. OFFICE: RIVERMILL LODGE, ST. IVES. (Ansafone). Overseas customers should send a bank draft in sterling drawn
Giro Ac. No. 278 9159. REGD. IN ENGLAND NO. 1328162 on a London Bank, or quote credit card number. PE 21

Practical Electronics October 1978 1109

 CHINAGLIA DINO-ELECTRICAL AND ELECTRONIC
TEST EQUIPMENT MANUFACTURERS
VALVE MAIL ORDER CO.
Climax House
Fallsbrook Road, London SW16 6ED

RST
THE
SPECIAL EXPRESS
MAIL ORDER SERVICE

E0 EP ED E0
DOLOMITI
£45
AA119
AAY30
0.20
0.13
BCY71
BCY72
0.12
0.17
M PSUO1
MPSUO6
0.32
0.40
.27X550
114914
0.16
0.07
7403
7404
0.20 20kfl/V arc. and d.c.
0-24
AAY32 0-15 BCZ11 1.50 IAPSU56 0.45 114916 0.07 7405 r)-ze
8A213 0.25 BD115 0.80 NK7401 2.00 1144001 0.06 7406 0.55
AAZ15 0.31 1313121 1.50 NK7403 1.73 1144002 0.07 0.55
AAZ17 0.ts BD123 1.50 N01404 1.73 1144003 0.011
7407
7408 0-25
A NEW HIGH SENSI-
AC107
AC125
0.75
5.30
130124
BD131 0.51
NESS5
0A5
0.45
0.75
1144004
1144005
0.09
0.13
7409
7410
0.21 TIVITY MULTIMETER
0.20
AC126 0.20 80132 0.54 0A7 0.55 1144006 0.15 7412 0.06 WITH ALL THE FEA-
AC127 0.25 0D135 0.35 0A10 0.55 0.15
AC128 0.20 430136 0.36 0847 0.14
1144007
1144009 0.15
7413
7416
0.45 TURES YOU WILL
0.40
AC141 0.25 130137 0.37 0A70 0.30 1144148 0.07 7417 0.40 EVER NEED
AC141K 0.35 .50138 0.00 0A79 0.30 1145400 0.14 7420 0.20
AC112 0.20 'B0139 0'43 0A81 0-30 1145401 0.16 7422 0'25
AC142K 0.30 BD140 0.47 0885 0.30 1S44 0.06 7423 0-25
Accuracy: D.C. ranges. 2-0%. A C n ranges 2 5%
AC176 0.25 130144 2.00 0A90 0.08 16920 0.08 7025 0.35 39 ranges: d.c. V. 0 150mV. 500mV. 1 5V. 5V. 15V. 50y. 150V. 500V. 5kV. 1
AC187 0.25 130181 1-36 0891 0.00 16921 0.00 7427 0.35 d.c.I. 0 50uA. 500uA. 5mA. 50mA. 0 5A. 5A. a c V. 51/. 15V. 50y.
AC188 0.25 80182 1.41 0A95 0.08 20301 1.00 7428 0.50 150V. 500V. 1 5kV, a.c.I. 5mA, 50mA. 0 5A. 5A. dB - 10 to 65 in
ACY17 0.155 130237 0.00 08200 0.10 20302 1.00 7430 0.20
ACY18 0.6.0 BD238 0.00 08202 0.11 213306 1.10 7432 0-36
6 ranges n 0 051(11 skn. sun. sookn. 5MO. 50MC1. pF 50kpF.
ACY19 0.60 1313010 0.75 0A210 0.75 214404 0.60 7433 0-37
500kpF.
ACY20 0.65 BDX32 2.25 08211 0.75 214696 0.25 7437 0.42
ACY21 0.65 80420 1.42 082200 0.65 214697 0.16 7438 0.37 Automatic overload protection and high Current range fusing.
ACY39 125 BDY60 0'75 08/201 0.65 214698 0.30 7440 (I-= Scale mirror and fine pointer for accuracy of reading. Single knob main
AD149 0.70 BF115 0.79 082206 0.65 214705 0.00 0.92
80161 0-75 BF152 0.15 OAZ207 0.65 2N706 0.12
7441814 range switching and all panel controls. C E I Class 1 movement with sprung
7412 0.78
AD162 0.75 BF153 0'25 0C16 1-2S 214708 0.21 7447AN 1.20 jewel bearings. Extended 92mm scale length for extra clarity. Compact ABS
AF106 0.4.0 BF154 0.25 OC20 2.00 214930 0.26 7450 0.20
case 125 N 131 ii 37mm. Weight 750g with batteries Supplied complete with
AF114 0.25 8E159 0.35 0C22 2.50 2141131 0.26 7151 0.20 carrying case, fused leads, handbook and full 12 -month guarantee. Optional
AF115 BF160 0'30 0C23 2.75 2141132 0.21 7453 0.20 30kV d c. probe available.
AF116 0.25 BF167 0'30 0C24 3.50 2141302 0.37 7154 0.20
AF117 0.25 BF173 0.39 0C25 0.90 2141303 0.37 7460 0.20
AF139 0.40 BF177 0.30 0C26 0.90 2141304 0.45 7470 0.35 Meter £50.00 incl. VAT (£1 P. & P.)
1.50 BF178 0.45 0C20
AF186
AF239 0.45 BF179 0.41 0C29
2.00
2.00
2141305
2141306
0.45
0.50
7472
7473
0.36
0.36
30kV Probe £12.85 incl. VAT
AFZ11 2.7s BF180 0.45 003.5 1.50 2141307 0.50 7474 0.40
AFZ12 2.75 BF181 0.45 OC36 1.50 2141308 0.60 7475 0.59
For details of this and the many other exciting instruments in the Chinaglia
ASY26 0.45 8E182 5'45 0C41 0.50 2141309 0.60 7476 0.42 range, including multi -meters. component measuring, automotive and
ASY27 0.50 BF183 0'45 0C42 0.50 2141613 0.33 7480 electronic instruments please write or telephone.
1.25
0.60
ASZ15 BF184 0.39 0C43 1.50 2141671 1.50 7482 0.85
ASZI6 1.25 BF185 0.37 00/4 0.50 2141893 0.33 7483 1.00
1.25 8F194 0.12

Al/C(0)Yr Instruments Ltd.

ASZ17 0C45 0.50 2N2147 1.40 7484 1.00
ASZ20 0.75 BF195 0.11 0071 0.45 2142148 1.65 7486 0.40
ASZ21 1.50 BF196 0.13 0072 0.45 2142218 0.33 7490 0.52
AD113 1.20 BF197 0-14 0073 1'00 2142219 0.42 7491AN 0.85
AUY10 1.70 BF200 0.32 0074 0.75 2142220 0-35 7492 0.60
BA145 0.15 *13E224 0.20 0075 0.150 2142221 0.22
BA148 0.15 8F244 0.35 0076 0.50 2142222 0.25
7493
7494
0.70 19 MULBERRY WALK. LONDON SW3 6DZ TEL 01-352 1897
0.80
138154 0.10 6F257 0.37 0077 1.20 2142223 2.75 7495 0.80
138155 0.12 5E258 0.42 °CAI 0.75 2142368 0.17 7496 0.90
BA156 0.13 BF259 0.45 0C1112 1.00 2N2369A 0.21 7497 3.67
BAW62 0.05 '8F336 0.50 0082 0'75 2142484 0.21 74100 1.75
88013 0.01 BF337 0.53 0083 0'55 2142646 0-50 74107 0.45
138016 0.07 BF338 0.55 0054 0.50 2142904 0-35 74109 0.55
BC107 0.12 BF621 2.27 0C122 1'50 2142905 0.35 74110 0.57
BC108 0.12 13E628 1.311 0C123 1'55 2142906 0.25 74111 0.86
0.13 BFS61 0-25 0C139
BC109
.15C113
.19C114
.E1C115
0.15
0.10
0.19
5ES98
BFW10
BFW11
0.25
0.90
0C140
0C141
2.25
1.95
2-25
075
2142907
.2142924
.2142925
2N2926
0.21
0.15
0.17
74116
74118
74119
1-89
0.95
2.00
THIS is the Catalogue you need
0.50 0C170 0.13 74120 1.10
BC116
.E1C117
130118
0.15
0.21
0.18
0.11
BFX84
BFX85
BFX87
137088
0.30
0.41
0'35
0C171
0C200
0C201
0.75
1.00
1.50
2N3053
2143054
2143055
0.25
0.50
0.65
74121
74122
74123
0.45
0.60
1.00
to solve your
BC125
.13C126
80135
0.25
0.10
BFY50
BE051
0'32
0'28
0'26
0C202
0C203
0C204 1.25
2143440
2143441
2143142
0.60
0.80
1.20
71125
74126
74128
0.10
0.80
0.00
component
'BC136
BC137
BC147
0.1s
0.16
0.10
BE052
BF061
BFY90
0-26
0'30
,...
.132
0C205
00206
00207
1.75
1-75
1.25
2143525
2143614
.2143702
0.90
1.20
0.15
74132
74136
74141
0.80
0.90
0-85
buying
BC148 0.10 EISX19 ...
5C149
BC157
.130158
0.13
0.12
0.11
BSX20
BSX21
BT106
034
0.32
1.25
OCP71
ORP12
F120088
.R2009
1.25
0433
2.25
2.25
2N3703
.2143701
2N3705
2143706
0.15
0-15
0.1
74142
74143
74144
3.00
3.00
3.00
problems
0.10 74145 1.00
BC159 0-13 5107914000 3.19 .R2010B 125 .2N3707 0.19 74147 2.15
BC167 0.13 .5U205 2.25 T1C44 0.36 .2143708 0.1 74148
0.16 2.00
.13C170 'BU206 2.25 11C2260 1.30 .2143709 0.15 74150 1.76
13C171 0.14 BU208 2.50 T11.209 0.25 .2N3710 0.14 71151 0.90
'5C172 0.13 50100 0.45 .71P29A 0.50 .2143711 0.15 74154 2.00
BC173 0.15 50126 0.14 .T1P30A 0.60 2143771 1-60 74155 0.90
BC177 0.19 134127 0.15 T1P31A 0.62 2N3772 1.70 74156 0.90
5C178 0.18 5Z561 0-20 114)32A 0.75 2N3773 2.65 74157 0.90
BC179 0.20 Series T1P33A 1.00 .2N3819 0.36 74159 2.50
The finest components
BC182 0.11 BZY88 0.13 T1P34A 1-20
13C183 0.11 Series T1P4IA 0-70
.2143820
.2143823
0.46 74170 2.60 catalogue yet published.
0.60 74172 5.00
.13C184 0.12 CR01 05 0-45 T1P42A 0-00 2143866 1.00 74173 1-75 128 A -4 -size pages.
13C212 0.14 CRSI 40 0.80 11P2955 1.00
BC213 0.14 CR8105 0.45 T1P3055 0.50
.2143904
.2143905
0-21
0.22
74174
74175
1.57
1.00
About 2,500 items clearly
5C214 0.17 CRS110 0.75 .11643 0.35 .2143906 0.22 74176 listed and indexed.
1.10
BC237 0.17 CR8160 0.90 .Z6140 0.25 .2N4058 0.20 74178 1.65
BC238 0.12 GEX66 1.50 ZSI70 0.12 .2141059 0.15 74179 1.65 Profusely illustrated.
GEX511 1'75 .26178
BC301
BC303
0-45
0.60 GJ3M 0'75 ZS271
0.54
0.22
2144060
2144061
0.20
0.17
74180
74190
1.65 Bargain List sent free.
1.48
BC307 0.20
0.10
GJ5M
6540378A
075
150
26278 0.56 .2144062 0-18 74191 1-48 At £1.00, incl. p. & p., the
.13C308 ZT8107 0.11 .2144124 0.17 74192 1-25
8C327 0.22 .K6100A 0'4° ZTX108 0.10 .2144126 0.17 74193 1-25
catalogue is a bargain.
BC328 0.18 ..M.).E34° 0'55 ZTX109 0.12 .2144286 0.20 74194 1-25
BC337 0.19 ''E37° 0'55 .218300 0.12 .2N4288 0.25 74195 1.10
BC338 0.10 MJE371 0'41 ZTX301 0.13 .2144289 0.25 74196 1.20 Send the coupon below now.
BCY30 1.00 MJE52° 0'55. Z1X302 0.17 2N5457 0.35 74197 1.00
5C031 1.00 0-7. ZT0303 0.1/ .2145458 0.35
MJES21
74198 2.25
BC032 1.00 ,2055 12.5 .ZTX304 0.19 2145459 0.35 74199 2-25 HOME RADIO (Components LTD 234-240 London Road. M.tcham Surrey CR4 3HO
5CY33 0.90 54.-1.3055 0-7. ZTX311 0.12 3N125 1.75 .76013N 1.75
BC034 0.90 M_P,F1°2 0'3° ZTX314 0.20
BCY39 3.00 ."''''1°3 0'3° ZTX500 0.13
EICY40 1-25 MPF104 0'30 .215501 0.14 INTEGRATED Plugs in socket
EICY42 0.30 L° ZTX502 0.16 -low profile IPlease write your Name and Address in block capitals
...MnPtl°,5. .0- CIRCUITS
.'''.^....
BC043
BC058
BCY70
0.32
0.22
0.111
PSA56 ''
..-..... 118503
ZTX504
ZTX531
0.17
0.20
0.20
7400
7401
7402
0.20
0.20
0.20
8 pin DIL
14 pin OIL
16 pin DIL
0.15
0.15
0.17
NAME

ADDRESS
Open daily to callers: Mon. -Fri. 9 a.m.-5 p.m.
Valves. Tubes and Trans stors Closed Saturday Prices correct I -
Terms C.W.O. only Tel. 01-677 2424-7
Quotations for any types not listed S.A.E. when going
Post and Packing 25p per order +8% V.A.T. to press I HOME RADIO (Components) LTD Dept PE
Items marked ' 123% 234-240 London Road, Mitcham Surrey CR4 3HD
Regd. No
9 1 2966 London)

1110 Practiial Flectronics October 1978

 Fight inflation with these super Hi-Fi offers. Compare these
QUALITY prices with the recommended retail prices and you will see

11141 AT BUDGET that you can save LULL-and what is more, you will be
purchasing quality equipment-that is why we are happy to
PRICES give these amazing guarantees.

TREMENDOUS SAYINGS
FOR THE HOME ENTHUSIAST
The MATSI TFS 60 Tuner/Amplifier
GOLDRING CK2 BELT -DRIVE
TURNTABLE CONSTRUCTION
KIT
AT LESS THAN
HALF THE
RECOMMENDED
RETAII PRICE

GOLDRING TURNTABLE
Due to a successful bulk purchase, we are happy
to offer this really top quality receiverfrom one of Available to personal
Japan's leading manufacturers at less than shoppers only, the
half price.15 watts per channel. FM/MW/LW. Goldring belt -drive
12 MONTHS GUARANTEE. Recommended turntable comes
Retail Price £144. OUR PRICE complete with high
Complete with arm, template and easy -to -follow instructions
(Securicor delivery 3.50) quality attractive
Ready for operation in a short time.
plinth and cover -
Wow/Flutter 0.15% peak.
Rumble -60 dB weighted. SANKYO STD -1610 STEREO 12 MONTHS
GUARANTEE.
Removable headshell.
Viscous damped cueing device.
CASSETTE
Easily adjusted tracking force and bias DECK
setting.
Two- speed, 16 -pole synchronous motor Features include Dolby
Dimensions: 37.8 x 28.3 cms. noise reduction system,
(Plinth, cover and cartridge available, Autochrome, Input/
onces on application.) Output Level Control,
R.R.P.I31.50
LION HOUSE PRICE
Postage and Packing E2
IP/ Peak Indicator, Auto -
stop, Ferrox Heads, )DAY'S VALUE £45
Tape -run Indicator,
LION HOUSE PRICE £25
MANY MORE EXCITING Hinged Dust Cover -
BARGAINS ARE AVAILABLE MORE FEATURES FOR Televis ons, Radios, Tape Recorders,
LESS MONEY - Music Centres, Cassette Recorders,
AT LION HOUSE-BRITAIN'S 12 MONTHS GUARANTEE -
HI-FI SUPERSTORE WITH THE Earphones, Quality Audio and Video
A beautifully compact machine of highest quality. Another successful
SUPERB DEMONSTRATION bulk purchase from Lion House at ONLYE Equipment, Hifi Accessories, Export
FACILITIES. (Recommended Retail Price £114.) 6915 elivery
d(Securicor
0.501 Televisons, In -Car Equipment,
Watches, Binoculars, Cameras,
RAMKO GULLIVER SPEAKERS GANT PERFORMERS Of
Calculators, etc and an entire floor
DWARF 11/(E DIMENSIONS
devoted to Musical Instruments -
all at keen prices!
Highly precise crossover network, matched
to component speakers, gives accurate
separation of audio spectrum and stable
frequence response.
Specially designed cabinets made of high
density chipboard with wood -welded
joints and individually tested. Finished in the
finest laminated rosewood veneer and
crafted and oil -finished by hand to a
distinctive lustre.
We are the sole agents and offer them
direct to you at only 17915 per pair.
(Securicor delivery £.3.50)

SPECIFICATIONS
Two- way mini hi-fi studio quality loud-
speakers. Despite their mini size, their clean,
solid bass range is equal to that of much
nigger systems, and the use of a high
10 -ounce precision ceramic magnet,
coupled to the dome, creates immense
flux providing excellent transient
responses. Acoustically suspended
Nominal impedance
System components

Frequency range
Sensitivity
8 ohms
4" woofer
1" dome tweeter
50-25,000 Hz
15-3 watt
Lion fiouse
LONDON'S HI -Fl SUPERSTORE
density, high temperature metal voice coil and impregnated with finest damping Nominal input 35 watt 227 TOTTENHAM COURT ROAD LONDON WI
system greatly enhances durability. In a room fluid, protecting dome against Music power 50 watt Tel (TI 580 7383 and 01 637 1601
filled with excitingly realistic sound, they distortion break-up or coloration even Dimensions 18 x11.5012 5 c, ,Telex 28394 LION G
seem almost undetectable. after prolonged heavy loading. Dome shape
-t inch woofers have high power handling and construction produces extra -wide Open 9 am to 6 pm Monday to Saturday
apability and areas efficient as 6 -inch dispersion, smooth frequency (Thursday until 7 um)
woofers. response and high resolution of WARRANTY
E xtra-light 1 -inch soft dome tweeters musical detail. Every RAMKO loudspeaker model is SAME DAY CREDIT Ux(LAYxxll0
weigh only 0.2 grams. A powerful FACILITIES
guaranteed for a period of five years. U112:111
TAX FREE EXPERT
Stockists for. A C . Amstrad, Aiwa, B S R Celestion. Empire. Fidelity. Goldring. Goodmans.Grunds Harmon Kardon. Hitachi. J B.L .Kef.KLH Koss, Monitor Audio, Micro, Marantz, National Panasonic,
National Technics, NAD, Nakamichi. JVC. Autofon, Philips, Quad, Revox, Sansui, Sennheiser, Shure, SME, Sony, Sharp. Superscope, Tannoy, Teac, Thorens, Transcriptor, Yamaha. etc

Practical Electronics October 1978

 Callers Welcome MON-SAT: 9.30-5.30
GODDARD'S COMPONENTS ORDER
DEPT. THURS: Closed all day
110 LONDON ROAD, St ALBANS, HERTS. All 1NX Lunch: MON-FRI: 1.30-2.30, SAT: 1.00-2.00

STEREO CASSETTE RECORDER DECK

HIT...Box SOCK -PROOF
POLYSTYROL IN GREY
4mm thick walls
Larger sizes are pillar fixing
with + solenoid auto -stop
Smaller sizes are slotted
+ Cr02 switch Inside Measurements:
+ piano key operation Box No. Breadth Length Height Weight
+ twin level meters mm mm mm gm
- + mic. sockets
1001 60 90 50 100

Tech. Spec.: 1 1002 75 130 61 175

Bias and erase freq. 88 kHz °
1003 90 160 71 285
4 ICs 8 Transistors
1 SCR 10 Diodes 1004 93 193 95 340
1005 125 220 110 575
Diagrams and top panel 1001 - 90p 1004 - E2.00
template supplied 1002 -£1.60 1005 -£3.00 TRADE ENQUIRIES WELCOME!

£25.75 + £1.25 p&p 1003 £1.80 50p each p&p. £1.00 for 3 p&p

DIGITAL CLOCK LCD WATCHES TOUCH GENTS r'--- LADIES S/S C652

£1.95
BATTERY DROP LEAF C TG
CLOCK MOVEMENT

Hrs. Mins. Date £14.95 6 .. x

Easy -to -set regulator screw I I, .'- 27
Size: 140mm x 85mm x SOmm i'l' 4,1 UNISEX C551 LARGE GENTS
Window size: 63mm x 28mm
No. height: 19mm 6 Colours Cl 65 ,
Date height: lOmm
Weight: 270gm
£11.95 . £9.95
ALL WATCHES 5 FUNCTION ... 1 YEAR GUARANTEE
£4.95 + 50p p&p P&P 50p per watch, Inc. Insurance
'We can also supply components for 'ELECTRONIC SOUND MONITOR' P.E. Sept. 1978ALL PRICES INCLUDE VAT

SEE THE
DOMM 110
40 0 ..tor
RANGE OF BOOKS IN THE NEW
DORAM HOBBIES 4110 0

CATALOGUE. # ;
_

MB
LOW PROFILE DIL SOCKETS - TIN PLATED READY DRILLED BLACK ANODISED HEAT SINKS
PRICE PER 1 5 10 25 T03 1440p 50E1.80
8 PIN 12p 65p £1.20 £2.50 T066 1040p 50E1.80
14 PIN 14p 70p £1.30 amo TO 3 x 2 1070p 50 E3.20
16 PIN 15p 85p £1.60 £3.40 HEAT SINK COOLERS. FITTING TO 5.
28 PIN 28p £1.50 £2.80 £6.00 NF 204 1014p 50 65p
40 PIN 44p £2.10 £4.00 E9.00 NF 205 10 12p 50 55p
STANDARD PROFILE DOUBLE -SIDED DIL - SOCKETS NF 207 1 4 13p 5* 60p
14 PIN 14p 65p E1.25 £3.00 NE 209 1 . 15p 5 4 75p
16 PIN 15p 70p £1.35 E3.25 INSULATING KITS. 5 WASHERS 10 BUSHES.
MOUNTING PADS 10/PACK 50/PACK MELINEX MICA
TO 5 4 HOLE 9p 40p TO 3 4 28p/KIT 4 30p/KIT
Doram Electronics Ltd TO 18 4 HOLE 9p 40p TO 66 4 28p/KIT 4 30p/KIT
CONVERTERS BUSH SHANK LENGTH REO: , 205, 153,
PO Box TR8, Leeds LS12 2UF TO 99 TO DIL 55p E2.50 125. 05, 025 125, 05, 025. For TO 3 only.
TO 10370 DIL 55p E2.50 TRANSISTOR INSULATION COVERS
Please send my FREE Hobbies Catalogue. TO 92/98 TO 005 9p 40p TO 3 5 a 35p 10 a 70p
TO 18 TO TO5 9p 40p TO 5 5 a 15p 10 a 25p
I enclose 25p contribution top. & p. (AVAILABLE LATE SEPT) TO 98 TO TO5 9p 40p TO 66 5 a 35p 10 .0 70p
DIODE CRADLES 10p 45p POWER SOCKETS
T03 1. 14p 5465p
Name LARGER RANGE OF TRANSISTOR PADS AND TO 66 1 4 16p 5 4 75p
INSULATING BUSHES IN CATALOGUE. ALL TO 220 INSULATING KITS 5 Washer 5 Bushes
PRICES INCLUDE V.A.T. MELINEX 20p/KIT MICA 25p/KIT.
Address...
POST AND PACKING 15p KITS/PADS/SOCKETS/COOLERS. 45p FOR ANODISED HEAT SINKS
Moulded Electronic Components Int. Ltd., Unit 3, Block 3, Vestry Estate, Oiford Road,
Sevenoaks, Kent

Drimm
FULL ILLUSTRATED CATALOGUE - SEND 30p FOR POST AND PACKING.
Doram Electronics Ltd
FROM MOULDED ELECTRONIC COMPONENTS
PO Box TR8, Leeds LS12 2UF
INT. LTD., Unit 3, Block 3, Vestry Estate,
Orford Road, Sevenoaks, Kent.
Overseas customers (except for N. Ireland) -60p Telephone: 0732 59246/7
including despatch by Air (or all -up post). Registered No. 211169600.

1112 Practical Electronics October 1978

 U.K. RETURN OF POST MAIL ORDER SERVICE also WORLDWIDE EXPORT SERVICE
R.C.S. 10 WATT MONO PRE -AMPLIFIER ROBUST BLACK PLASTIC BOX
Size 6} x 31 x 2in with brushed aluminium £1.50
A mains operated solid state pre -amplifier unit designed facia.
AMPLIFIER KIT to compliment amplifiers without low level phono and tape
Ideal for constructional projects. Post 30p
input stages. This free standing cabinet incorporates R.C.S. LOW VOLTAGE STABILISED
circuitry for automatic R.I.A.A. equalisation on magnetic
phono input and N.A.B. equalisation for tape heads. Power POWER PACK KITS
All parts and instructions with Zener diode,
ON/OFF, PHONO/TAPE switches and pilot lamp are on
the front panel; phono socket
printed circuit rectifiers and double wound
mains transformer Input 200/240V c Output
£2.95
input and output are rear voltages available 6 or 7 5 or 9 or 12V d c up to 10Ornro orst 41e5ss
This kit is suitable for record players. tape play back. gust rs, located. AC mains 240V. Size 3 24 thin Please state voltage required
electronic instruments or smell P.A. systems. Two versions are Size 6 x 3; x 2in. Post 50p
available. The mono kit uses 13 semiconductors. The stereo kit ELECTRO MAGNETIC
uses 22 semiconductors. Both kits have printed front panel and
volume. bass and treble controls. Spec. lOW output into 8 ohms.
£4.50 ea. -2 for £8. PENDULUM MECHANISM 95pPost 301,

1 5V d c operation over 300 sours continuous on SP2 battery, fully

7W into 15 ohms. Response 20cis to 30kcie adjustable swing and speed Ideal displays. teaching electro
input 100M.V. high imp. Size 91 x 3 x 2in. A/C mains operated. magnetism or for metronome. strobe. etc.
BAKER MAJOR 12 INCH f16.88
::" £12.50 Stereo
£20
Easy to build Full instructions supplied
asps Post El 00
30-14,500 c/s. 12in double cone, woofer
BSR AUTOCHANGER
and tweeter cone together with a BAKER Plays 12in. 10in or 7in records Auto or
ceramic magnet assembly having a flux Manual. A high quality unit backed by
BSA reliability with 12 months
ELAC SPEAKER density of 14,000 gauss and a total flux
01 145,000 Maxwells. Bass resonance guarantee .c. 200/250V Size 13}
114in. Above motor board 3t in Below
10 inch £4.50 40 c/s. Rated 25W.
NOTE 4 or 8 or 16 ohms available. motor board 24 in
With STEREO/MONO CARTRIDGE £12.95 All Post 75p
Large ceramic Module kit, 30-17.000 c/s with tweeter,
Single Player version f 17.50
magnet 50-16,000 c/s. crossover. baffle. 19 0 12}in. BSR P126 with Magnetic Cartridge E24 50
Bass resonance 55 c/s. 10W.
instructions. As illustrated. £20.52 GARRARD AUTOCHANGER plays all records
BSR P163 BELT DRIVE DECK. less cartridge
1:1 4 95
E27 50
Please state or e or 16 ohms Post Cl 60
8 ohm impedance. GARRARD AP76 Single Player less cartridge E27 50
RCS STEREO PRE -AMP KIT. All parts to build this pre -amp.
Inputs for high, medium or low Imp. per channel, with volume
"BIG SOUND" BSR DE LUXE AUTOCHANGER
Features balanced arm. Cueing device,
stylus pressure gauge. 3 speed - plays
Control and P.C. Board. Can be ganged to make multi -way mixers. BAKER SPEAKERS all size records. Fitted with stereo
£2.95 Post 350 Robustly constructed to stand up to long
periods of electronic power. As used by leading
ceramic cartridge. Size:
13. 12ins. Post Et £17.50
MAINS TRANSFORMERS ALL POST 75p each groups and discos Useful response 30-13.000 Or with Sonotone V100
£21.50
2513-0-250V 70mA 6 3. 2A t3.45 c s Bass Resonance 55 bs magnetic cartridge
250-0-250 80mA. 6 3V 3 5A. 6 3V lA or 5V 2A
350-0-350 80mA, 6 3V 3 5A. 6 3V to or 5V 2A
£460
£5.110
GROUP "25"
300-0-300 120mA 2 x 6 3V 2A C.T., 6,3V 2A U 50 121n "W
220V 45mA, 6 3V 2A £1.75 4 8 or 16 ohms £12.96
HEATER TRANS. 6 3V 3A. 01.45. 3. amp £1.00
GENERAL PURPOSE LOW VOLTAGE. Tapped outputs at
2A 3. 4, 5. 6. 11. 9, 10, 12. 15. 18. 24 and 30V 7.530 GROUP "35-
IA. 6. 8. 10. 12. 16. 18. 20, 24. 30. 36, 40, 48 60 t5 30 12In 40W
2A. 6. 6. 10. 12. 16, 18. 20, 24. 30. 36. 40. 48. 60 £11150 4 8 or 16 ohms £15.12 R.C.S. DISCO DECK
3A. 6. 8. 10. 12. 16, 18. 20. 24. 30, 36. 40. 48, 60 111.00 Post CI
5A, 6. a. 10. 12, 16, 18. 20. 24. 30, 36. 40, 48. 60 £14.50
5, 8, 10. 16V 4.4 £2. 12V 103mA £1. 12V 300mA Ct. GROUP 50/12in SINGLE RECORD PLAYER
12in OW Fitted with auto slop, stereo compatible cartridge. Baseplate. Sae
12V 750mA £1.30.40V 2A tapped 10V or 30V £2.96.
10-0-10V. 2A £2.50. 40V 2A £2.95. 30V 5A 34V 2A ct. £3.75.
4 or 6 or 16 ohms with
aluminium presence dome £22.68 11 x 8.iin Turntable Size 7in diameter a c mains 220.250V
3 speeds plays all size records
Post Cl 60
2 x 18V 6A E9. 12-0-12V 2 amp £2.95.
20-0-20V 1A £2.95. 30V 11A £2.75. 20V 1A £2.20.
Two for £15. Post 75p. £7.95 P:5Ta
9V 3 amp £2.75. 60V, 40V,20V or 20-0-20V, 1A £3.150. GROUP 50/15in
30-0-30 2A £7. 9V 250mA £1.30. 30V 2 amp £3. 15in 75W
8 or 16 ohms £28.08 HEAVY METAL PLINTHS
AUTO TRANSFORMERS. 115V to 230V or 230V to 115V With P V C Cover. Cut out for most B.S R or
150W £5; 250W E6; 400W £7; 500W £8.
CHARGER TRANSFORMERS. Input 200/250V for 6 or 12V
Post Cl 60
Disco. Group - PA Cabinets in stock. Send for
Garrard decks. Silver grey finish.
Model "A ' Size 124 x 144 x
£6 50
14.A £2.75; 4A £15.20. Model "I3-. Size 16 x 134 x 7in. £7.50. Post £1.50
Leonel Cabinet Fittings, Handles, Corners,
FULL WAVE BRIDGE CHARGER RECTIFIERS. 6 or 12V outputs Feet, Covering Material all In stock. Extra Large Plinth and Cover. For transcription decks. Size
1-4A 55p; 4A C1.25. HALF WAVE 12V 14-A 25p. 20 x 171 x 9in. uncut board. Shop callers only £18.150.
BAKER 150 WATT TINTED PLASTIC COVERS ONLY
GOODMAN'S COMPACT 12in ALL PURPOSE Sizes: 144 x 124 x 41in, £3.
1610 14 4in. t`4.
BASS WOOFER TRANSISTOR 15 x 134 x3in, £3.50. 174 x 94 x 34in, £3.
144 x 141021in Rosewood sides t4.
Standard 12in diameter fixing with cut sides 12 x AMPLIFIER Ideal for record decks, tape decks, etc. Post £t.
10in 14,000 gauss magnet 20 watt r.m.s. 4 ohm ideal for Groups. Disco, P A and Musical Instruments 4 inputs
'mpedance. Bass resonance 30 c.p.s. Frequency
response 30-8,000 c.p.s. £9.95 each. Post e1.00.
speech and music 4 way mixing Output
4/8/16 ohm. s.c. Mains 240V.
BAKER HI-FI SPEAKERS
Separate treble and bass controls. £85 Ct 50 HIGH DUALITY -BRITISH MADE
10 WATT PER CHANNEL STEREO AMPLIFIER
In chassis form. A.G. mains operated. Volume, NEW "DISCO 100 WATT" £59 SUPERB £24.75
balance, treble and bass slider controls. ALL TRANSISTOR AMPLIFIER Carr. Et
Pick up and tape inputs. Recording output. Socket. 2 inputs 4 outputs separate volume treble and bass controls. Ideal
disco or slave amplifier chassis Made by Jennings
12in 25 watt Post /1 60
Front panel size: 16+ x 1iin. (Duality loudspeaker. low cone resonance
Chassis size: 13 x 1Sin. Bargain £1850 Post 50p e so es clear reproduction of the deepest
R.C.S. SOUND TO LIGHT DISPLAY MK II bass Special copper drive and concentric
Complete kit of parts with R.C.S. printed circuit. Three tweeter cone Full range reproduction with
1000W channels. Will operate from 20mV signal source. remarkable efficiency in the upper
HEATING ELEMENTS WAFER THIN CABINET extra f4. register.
Size 10i 8; n Operating voltage 200 250V a c 250W KIT --£17.00 Bass Resonance 25 c,s
approx Suitable for Heating Pads. Food Warmers. Convector Flux Density 16.500 gauss
Heaters. etc Must be clamped between two sheets of metal or GOODMANS CONE TWEETER Useful response 20-17.000 cis
8 or 16 ohms models
asbestos ONLY 40p EACH (FOUR FOR £1.50) 18,000 cis 25W 8 ohm Price £3.25
ALL POST PAID -Discounts for quantity 3 WAY CROSSOVER WITH TREBLE & MID RANGE
CONTROLS. 50 WATT. ES POST £1.
AUDITORIUM £22.68
Post
E.M.I. 13i x 8in 12in 35 watt ft 60
SPEAKER SALE! R.C.S. 100 WATT VALVE A full range reproducer for high power
Electric Guitars. public address, multi -
Mtn tweeter. And crossover. AMPLIFIER CHASSIS speaker systems. electric organs. Ideal for
Hi-Fi and Discotheques
10W Model £7.95 Bass Resonance
Flux Density
35 c's
15.000 gauss
State 4 or 8 ohm Post 45p Useful response 25-16,000 c s
15W model £10.50 8 or 16 ohms models
8 ohms Post 65p

20W model £11.50 AUDITORIUM £28.08

Professional model. our inputs. Treble, Bass. Master Volume
State 8 or 15 ohms. Post 75p Controls. Ideal disco. P.A. or groups. S.A.E. for £99 15in 45 watt Post C1 60
TEAK VENEER HI-FI SPEAKER CABINETS
details. 5 speaker outputs. 3 or 8 or 15 ohm 100V line to
order. Suitable carrying case £16.50. plus 12,50 carr BLANK ALUMINIUM CHASSIS, 18 s.w.g. 21in. sides, 6 x 4in.
MODEL "A" 20 x 13 x 12in. 95p; 8 x 6in £1.40; 10 x 7in. £1.55; 14 x 9in. 0.90: 16 x 6in.
For 12in. dia. or 10in. speaker. LOW VOLTAGE ELECTROLYTICS £1.85; 12 x 3in. £1.20; 16 x 10in. £2.20; 12 x 8in. £1.70.
1 2. 4 5. 8. 16. 25. 30. 50. 100. 200rnF 15V 10p. 500mF 12V 15p; ALUMINIUM PANELS, 18 s.w.g. 6 x 4in. Up; 8 x 6in. 38p;
Illustrated £14.50 Post £1.60 25V 20p; 50V 389. 1000mF 12V 17p; 25V 35p; 50V 47p; 100V 70p. 10 x 7in. 54p; 12 x 5in. 50p; 12 x 8in. 70p; 16 x 6in. 70p:
MODEL "B" BOOKSHELF 2000mF 6V 25p; 25V 42p. 2500mF 50V 112p; 3000mF 25V 47p; 14 x 9in. 94p; 12 x 12in. £1; 16 x 10in. E1.16.
WV asp. 3900mF 100V £1-60. 4700mF 63V 11.20. 5000mF 6V 25p; ALUMINIUM ANGLE BRACKET, 6 x 1 x $n. 15p.
For 13 s 8in. EM) 12V 42p; 25V 75p; 35V asp; 5600mF 76V VIM; 1200/78V 80p. ALUMINIUM BOXES. MANY SIZES IN STOCK
Loudspeakers. £8.50 Post £1 4 x 2 x 2in. 86p; 3 x 2 x lin. 86p; 6 x 4 x 2in. 95p; 8 x 6 x 3in.
£1.50; 9 x 4 x 4in. £1.70; 12 x 4 x 4in. £1.95.
R.C.S. BOOKSHELF complete with HIGH VOLTAGE ELECTROLYTICS
speakers. Size 14 x 9 x 6in. approx. 8/350V 22p THE "INSTANT' BULK TAPE ERASER £4.95
8+8/450V 50p 50+50/300V 50p Suitable for cassettes. and all sizes of
Response 50 to 14,000 cps 16/350V 30p 8+16/450V 50p 32+32/450V 75p tape reels a c mains 200/240V post
12 watt rms 8 ohms £19 pair Post £1.50 32/500V 75p 16+18/450V 50p 100+100/275V 65p Leaflet S A E 50p
ACOUSTIC WADDING 18in. wide, 20p ft. 50/350V 50p 32+32/350V 50p 150+200/275V 70p Head demagnetiser £4.75

RADIO COMPONENT SPECIALISTS 337 WHITEHORSE ROAD, CROYDON, U.K. Tel. 01-684 1665
Minimum post 30p. Acces/Eurocard and Barclaycard/Visa. Same day despatch. Radio Books end Components Lists 20p. Open 9-6 Wed. 9-1 Sat. 9-5 (Closed for lunch 1.15-2.301

Practical Electronics October 1978 1 I 13

L
 GREENWELD
443 Millbrook Road Southampton
-r
11_
56 FORTIS GREEN ROAD, MUSWELL HILL N10 3HN
Ig electronics
TELEPHONE: 01-883 3705
SO1 OHX Tel: (0703) 772501
All prices quoted include VAT. Add from schools, etc. (Minimum invoice
25p UK/BFPO Postage. Most orders charge £5). ExporVVVholesale enquiries
despatched on day of receipt. SAE with welcome. Wholesale list now available
enquiries please. MINIMUM ORDER for bona -fide traders.
VALUE £1. Official orders accepted ponente always wanted.
Surplus corn - OUR LATEST
BUY A COMPLETE
EXPERIMENTERS
CALCU LATOR
CATALOGUE
Based on the C500 chip, this pack of parts
enables the more experienced constructor to CONTAINS FREE
RANGE OF make an 8 digit 4 function calculator. The
comprehensive data supplied includes full
size layout of PCB required, types of suitable 45 pence WORTH
display and keyboard that can be used etc.
COMPONENTS AND Components included in the pack are C500
calculator chip, driver IC. all components for
inverter/clock circuits, R's C's etc. All for only
OF VOUCHERS
THESE PACKS WILL £3-SO.
CONTAINS MICROPROCESSORS +BOARDS,
TRANSFORMERS
HELP YOU All mains primary: 12-0-12V 50mA 85p; MEMORIES, TTL, CMOS, ICs, PASSIVES, ETC., ETC.
100mA 95p; 1A £2.50. 6-0-6V 100mA
85p: 11A £2.40. 9-0-9V 75mA 85p: 1A
£2.10. Multitapped type 0-12-15-20-24-
* SAVE ON TIME -No delays in
waiting for parts to come or
30V, 1A £3.95; 2A £5.35; 3A £6.90 20V
21A £3.90: 25V 13A £2.25; 12V 8A £4;
24V 5A £7.50; 0-22-34-41V 4A £7.50; 20V
SUPERSAVERS
shops to open! Cr 300mA twice £2.50; 12V Is 250mA
twice £2.00 ALL FULL SPEC DEVICES
* SAVE ON MONEY -Bulk buying
means lowest prices -just RELAYS TEXAS TIMER RED LED
W847 Low profile PC mntg 10x33 x20mm
compare with others! 6V coil, SPCO 3A contacts. 93p
W812 Sub. min type. 10x 19x 1 Omm 12V
coil DPCO 2A contacts C1.15
741 555 TIL209 NC CLIPI
* HAVE THE RIGHT PART -No w 7 01 6V SPCO to contacts
guesswork or substitution 20 x30 x25mm Only 56p 5 for 4 for 10 for
W817 11 pin plug in relay, rated 24V ac, but
necessary! works well on 6V DC. Contacts 3 pole do
rated 10A. 96p
W819 12V 1250R DPCO 1.4 contacts. Size
29 x22 x 18mm, min plug-in type 72p
£1.00 £1.00 £1.00
ALL PACKS CONTAIN FULL SPEC, BRAND W839 50V ac 124V DC) coil. 11 pin plug in VAT INCLUSIVE PRICE + 25p P. & P.
NEW. MARKED DEVICES- SENT BY type. 3 pole don0A contacts Only 85p
RETURN OF POST. VAT INCLUSIVE W846 Open construction mains relay. 3 sets
PRICES.
1(001 50V ceramic plate capacitors. 5%. 10
ofeach
ea value 22pF to 1000pF. Total 210,
10A c/o contacts. £1.20
Send SAE for our relay list - 84 types listed
and illustrated.
A4 IC BOOKLET
1(002 Extended range. 22pF to 0.1pF. 330
SUPPLIED FREE WITH ORDERS OF ANY ICs WORTH £5.00
£490 STEREO AMPLIFIER OR MORE, CONTAINS CIRCUITS, PIN CONNECTIONS AND
K003Polyester capacitors. 10 each of these
Koss CHASSIS £5.50
values, 0.01. 0-015, 0022. 0.033, 0.047,
0068, 0.1, 0-15, 0.22, 033, 0.47pF. 110 Complete and ready built. Controls: bass.
DATA (35p + SAE IF SOLD ALONE).
he for £475 treble, volume/on-off, balance. 8 transistor
;I:Flgrr
Mylar capacitors, min 100V type. 10 circuit gives 2 watts per channel output. Just
needs transformer and speakers for low cost
each all values from 1000pF to 10,000pF.
Total 130 for £3.75 stereo amp. Suitable metal cabinet (W3741
K005 Polystyrene capacitors, 10 each value £2.00 - or buy the amp, case and trans -
from 10pF to 10.000pF, E12 series 5% former for £1000 and get DIN speaker
160V. Total 370 for £12.30 sockets and knobs freer!
8008 Tantalum bead capacitors. 10 each of
the following: 0.1. 0.15, 0-22, 0.33, 0.47,
0-68. 1, 2.2. 3.3, 4-7, 6.8, all 35V; 10/25 AMPLIFIER KIT £1.75
CRESCENT RADIO LTD.
15/16 22/16 33/10 47/6 100/3. Total 170 Mono gen. purpose amp with tone and 1 ST. MICHAELS TERRACE,
tants for £1420 Vol/on-off controls. Utilizes sim. circuitry to WOOD GREEN, LONDON, 01-888 4474
1(007 Electrolytic capacitors 25V working, above amp. Output 2W into 8 ohms. Input N22 4SJ (MAIL ORDER DEPT.)
small physical size. 10 each of these popular matched for crystal cartridge. 4 transistor
values: 1, 2.2. 4.7, 10, 22, 47, 100pF. Total circuit. Simple to build on PCB provided. Can
70 for £350 be either battery or mains operated. (For 3 KILOWATT PSYCHEDELIC
K008 Extended range, as above, also includ-
ing 220, 470 and 10008F. Total 100 for
mains powered version add £2.20 for suit- TELESCOPIC AERIAL LIGHT CONTROL UNIT
able transformer.) Blue vinyl covered 8 Section Telescopic Aerial
5.90 aluminium case to suit (W3721 £1.30 Length, extended: 96 cm. (37r) 1000W lighting per channel. max.
K021 Miniature carbon film 5% resistors, Length, closed: 16 cm. (63"1 A 3 channel sound to light unit housed in a
CR25 or similar. 10 of each value from 10R Nut and bolt fixing at base of aerial. robust metal case, with a sensitivity control
to 1M, E12 series. Total 610 resistors, £6.00 TMS4030 RAM Only 70p each + 12.1% VAT for each channel i.e. Bass. middle and treble.
K022 Extended range. total 850 resistors 4096 bit dynamic RAM with 300ns access Full instructions make this unit easy to
from 1R to 10M £8.30 time: 470ns cycle time: single low connect to your present amplifier.
K041 Zener diodes. 400mW 5% BZY88, etc. capacitance high level clock i/p. ally TTI. . sheet.
fnor speC2c00
10 of each value from 2.7V to 36V. 624 compatible: Low power dissipation. Supplied "FLIP"! Still only 0. + 8% VAT.
series. Total 280 for £1 530. with data £2.75 AN ELECTRONIC VERSION OF TWO-UP
K042 As above but 5 of each value £8.70 OR ODDS AND EVENS.
We supply a complete kit of parts which POWER SUPPLY UNIT
MISCELLANEOUS IC's includes a strong case and attractive front PP1 - switched 3, 43, 6, 73, 9 and 12 volts
DIODE SCOOP!!! panel to give the finished game a long life at 500mA, with on/off switch and pilot light.
We have been fortunate to obtain a large Supplied with data if requested. MC3302 and professional appearance. Size: 130 x 55 x 75mm approx.
quantity of untested, mostly unmarked glass
quad comp. 120p; 710 diff comp. (T0991 Full assembly instructions are supplied. 'If Our Price: £6.00 a. 8% VAT
silicon diodes. Testing a sample batch
40p: ZN1034E precision timer £2.25; you can solder you can make this great game.
revealed about 70% useable devices - signal LM7I 1 Dual duff comp 85p; LM1303 dual An ideal first project to introduce you to ,
diodes, high voltage reds and zeners may all stereo pre -amp 75p; MC1469R voltage reg electronics. SIX -PIECE
be included. These are being offered at the 0.150. UPC1025H audio £350; 575C2 Not only will 'FLIP' start you on a great
audio £2.88; TDA2640 audio £2.92;
incredibly low price of 0 .25/1000 - or a bat hobby but you will own a game which will MINIATURE .
I
of 2500 for E2.25. Bag of 10,000 £8. Box orSN75110 dual line driver 70p; MC8500
CRCC gen POA
amuse you and your friends for hours. SCREWDRIVER i i
25.000 £17.50. Box of 100,000 M. Complete Kit: £5.25 a- 8% VAT
Post Free! SET
I

..,
HEAT SINK OFFER Six precision screwrInvers Irl
Copper T05 sink 17mm dia x 20mm. 10 for BARGAIN LOUDSPEAKER a hinged plastic Blade ... . . li
4 40p; 100 for £3; 1000 for £25 Goodmans 5' 8 ohm long throw heavy duty sizes, "rnm, "mrn. 2n..

PC ETCHING KIT MK III

L/SPKR.
Mounting plate is inte9ral with L/S chassis
and has fixing holes with centres spaced at
2.4mm 2.9mm. 3.8mm.
Our Price: £1.75 + 8% VAT I
Now contains 200 sq. ins. copper clad board. Onlyaoaly)
1 lb. Ferric Chloride, DALO etch -resist pen. E5.00 + 12196 VAT. PIEZO ELECTRIC HORN
abrasive cleaner, two miniature drill bits, UNITS
etching dish and instructions. £4.25 High Quality. High Power Tweeter. No Xover
2 WAY 8 OHM regd. Freq. Response: 3.8kHz-28kHz. Spec.
SIGNAL INJECTOR sheet sent on receipt of S.A.E.
This handy little instrument made to a very VERO OFFCUTS HEAVY DUTY XOVER. Our Price: £6.50 + 8% VAT.
high standard at a very attractive price is just Pack A. All 0. 1" Pack B, All 0.15"
A 2 way 8 ohm H/D )(over suitable for L/S
the job for fault finding on radios, amps. etc. Pack C, Mixed Pack D. all 0.1" Plain systems up to 100W. Input via screw ter-
Ready built and tested just needs one HP 7 Each pack contains 7 or 8 pieces with a total minals. Fitted with a 3 position 'HF LEVEL' BARGAIN TRANSFORMER
battery. area of 100 sq. in. Each pack is a ao. Also switch which selects either Flat. -3dB or 240V Primary 12-0--12V 500mA sec.
available by weight. llb £420, 101b £32.50. -6dB. Approx. size: 60 x 40 x 50mm, Fixing
ONLY £2.00 Buy now while stocks last! centres: 75mm.
17 x 31" Strips: 0.1" £2.20; 10 for £15 Only f3.00 8% VAT. Price: Cl .50 + 8% VAT.
74 SERIES PACK 0-15" C1 .98
0.1" Plain Cl 83
Selection of boards containing many different
74 series IC's. 20 for f1; 50 for £2.20; 100 'P&P' orders up to £5, Add 30p.
for E4. EDGE CONNECTORS Access BARCLAYCARD1
O £5-£ 0, Add 50p.
DISC CERAMIC PACK
Amazing variety of values and voltages from
a few pF to 2.2u F 3V to 3kV i 200 El. 500
£2.25. 1000 £4.00
Special purchase of these 0.1" pitch double -
sided gold-plated connectors enables us to
offer them at less than one-third of their
original list price!
18 way 41p; 32 way 72p; 40 way 90p. -
Mt& All orders over El 0 post free!
Please add V.A.T. as shown.
S.A.E. with all enquiries please.
VISA
)
Personal cellars welcome at: 21 GREEN LANES, PALMERS GREEN, N.13.

1114 Practical Electronics October 1978

 Marsha
A. Marshall (London) Ltd, Dept. PE. Head Office mail order: Kingsgate House, Kingsgate Place, NW6 4TA. Tel: 01-624 0805. Retail Sales London:
40-42 Cricklewood Bdwy, NW2 3ET. Tel: 01-452 0161/2. Telex: 21492. London: 325 Edgware Rd, W2. Tel: 01-723 4242. Glasgow: 85 West
Regent St, G2 2QD. Tel: 041-332 4133. Bristol: 1 Straits Pde, Fishponds Rd, BS16 21X. Tel: 0272 654201.
20698 0.39 202219 0.38 2143397 294062 020 205247 044 40410
eame a#tai
Call in and see us 9-5.30 Mon -Fri 9-5.00 Sat
Express Mail Order Tel. orders on credit cards £10 min.
Trade and export enquiries welcome

602148 011
0
a '9,tear'eteat"

0.18 0.82 005490 0.14 0132444 0.70 61182 0.37 81589 1.37 MJE520 0.50
20697 0.31 202219A 0.39 293438 0.85 254064 1.35 205248 0.44 40411 3.10 BC214C 0.17 005490 0.15 8D244C 0.87 61183 0.44 8E050 0.27 MJE521 070
25698 049 252220 0.39 203440 0.75 204074 2.65 295294 0.44 40594 0.87 80147 0.13 601826 0.13 BC2141 0.18 BC557 0.14 002454 0.69 81184 0.41 61051 0.27 MJE2955 195
25699 0.58 202221 025 203441 092 204121 0.27 205295 9.44 40595 0.98 6C1470 On BC1821 0.15 60214113 018 00558 0.13 1317245C 0.85 0F185 0.37 131052 021 MPF3055 1.05
20706 0.30 2922214 0.25 253442 145 204122 0.27 205296 0.44 40673 0.80 B0148 0.13 8018214 0.15 BC214LC 0.18 BC559 0.15 802464 0.72 0F194 0.16 8E090
1.35 MPF102 0.33
2117064 0.30 292222 015 253638 0.17 204123 0.19 205298 044 40869 1.30 1301480 0.13 BC182LB 0.15 0023713 0.15 BCY70 0.21 80246C 0.93 01195 0.16 0.55
08101 MPF103 0.44
25708 0.30 2N2222A 025 29313384 0.17 204124 0.19 205447 0.16 AC126 0.48 BC1480 0.13 80183 0.12 BC2384 013 BCY71 0.26 1311433 0.44 61196 0.16 0.55
BRY39 MPF104 0.44
20718 030 252369 0.27 203702 0.14204125 0.19 255448 0.16 AC127 0.48 BC149 0.15 001834 0.12 BC2388 0.13 BCY72 0.18 80434 0.46 8E197 0.16 0.35
130419 MPS105 0.44
257184 0.54 2523694 0.27 203703 0.14 204126 0.19 295449 0.20 AC128 0.48 BC149C 0.15 0018313 0.13 BC238C 0.13 60115 0.68 60435 0.46 61198 0.19 BSX20 0.35 MPS405 027
201720A 0.85 292646 0.80 203704 0.14 204284 0.38 295457 0.38 AC151 0.43 801574 0.15 801830 0.13 8C2390 0.16 60131 0.55 60436 0.46 61199 0.19 0S421 0.35 MPS406 017
211722 0.45 202647 1.55 203705 0.14 204286 0.22 205458 0.35 AC152 0.54 BC1584 0.15 601831 0.15 002390 0.17 80132 0.75 00437 0.55 012242 0.22 60104 1.80 MPS412 0.44
214727 0.50 202903 1.60 203706 0.14 204287 0.22 205459 0.32 AC153 0.59 13015813 0.15 8C183LA 0.15 6C2574 0.18 90135 040 60438 0.55 012252 0.27 81.1105 1.55 MPS414 0.33
20914 0.38 202904 0.31 203707 0.14 204288 0.22 205460 0.65 401534 0.59 BC1594 0.17 8018318 0.15 0C2586 0.19 60136 040 60529 0.49 0F2444 0.36 811126 1.08 MPSA55 0.27
2N916 0.33 2029044 0.31 2113708 0.12 2144289 012 205484 0.37 4C1764 070 0C1596 0.17 BC183LC 0.15 B02590 0.19 80137 0.41 60530 0.55 6124433 033 00204 2.20 MPS456 027
20917 0.38 202905 0.31 253709 0.12 204347 2.20 205485 0.40 AC176 0.54 80160 0.38 80184 0.12 80300 0.43 80138 0.41 60535 0.70 012454 OM B0205 2.40 R20088 2.45
20918 0.45 2029054 0.31 203771 2.16 294348 2.65 205486 0.40 A0187 059 0C1131 0.38 001840 0.13 BC301 043 6D139 0.43 60536 0.70 812458 0.44 00206 2.70 020108 2.15
29929 0.37 202906 0.25 203772 2.20 204918 0.65 205490 0.64 401874 055 8C167 0.13 0C1840 0.13 BC302 0.37 60140 0.43 60537 0.74 81257 035 60208 2.70 711294 0.49
2019294 0.37 2029064 0.25 293773 3.15 2N4919 0.70 205492 0.64 AC188 0.54 601676 0.13 801841 0.15 00303 0.54 80181 1.90 80538 0.77 81256 035 ME0401 0.22 TIP29C 065
214930 0.37 202907 0.25 203819 0.36 204920 0.63 2N5494 0.65 4C188K 0.65 60168A 0.13 0018418 0.15 80307 0.16 00182 220 00539 0.60 81259 035 ME0402 0.22 TIP304 0.54
20930A 0.95 2029074 0.25 203820 0.39 204921 0.54 205496 0.67 40181 100 0C1688 0.13 BC184LC 0.15 0C3074 0.16 80183 2.35 60540 0.60 0F336 042 ME0404 0.17 TIP30C 0.70
201711 0.30 202923 0.17 203821 0.96 254922 0.60 206027 0.64 40162 1.00 8C1138C 0.13 B0212 0.15 13030711 0.16 130187 0.95 80X14 1.32 BF337 049 ME0412 0/2 TIP314 0.54
201889 0.30 292924 0.17 203900 0.28 294923 0.75 2146107 0.45 AE106 0.60 8C1698 0.13 BC2124 0.15 80308 0.16 BD235 0.46 BDX18 1.90 61338 0.52 ME0414 0.22 TIP31C 0.72
201890 030 202925 0.19 2113901 0.30 2144924 1.15 206108 0.55 AF109 0.52 80169C 0.13 BC2120 0.15 8C3085 516 BD236 0.44 80020 1.10 81639 0.30 ME4001 0.16 TIP324 0.59
201893 0.30 202926 0.17 253903 020 205086 0.30 206109 0.55 60107 0.16 80177 0.22 BC212L 0.18 0C3090 516 60237 0.44 60155 1.80 13F040 0/9 ME4002 0.16 TIP32C 022
202102 0.60 203053 0.25 2113904 0.16 205087 0.30 256111 0.48 B01074 0.16 801774 0/2 8C2121.11 0.16 13C3098 516 BD238 0.44 80056 2.10 81041 0.30 ME4003 0.16 TIP41A 0.76
202192 0.58 253054 0.72 253905 0.18 2145088 010 206121 1141 BC107B 0.16 BC17713 0.25 0C2121.6 0.18 0C3090 016 602394 0.44 81115 0.39 81019 0.30 M(4101 0.11 TIP410 0.97
2112193 0.50 2N3055 0.75 203906 0.18 2145089 0.30 206122 0.44 80108 0.16 BC178 0.22 6C213 0.15 BC327 0.22 BD239C 0.59 01160 0.33 61080 030 ME4102 0.11 11P424 0.86
21421934 052 203390 0.50 204031 0.55 2145190 0.65 208123 0.48 8010134 0.16 801784 0.25 BC2134 0.15 BC328 0.20 002400 0.40 BF161 0.65 BFR81 030 ME4103 0.11 TIP42C 1.08
202194 042 203391 0.40 204032 0.65 205191 0.75 206124 0.45 601088 0.16 0017813 0.35 002130 0.15 6C337 520 602400 0.59 01167 0.37 81029 0.34 ME4104 0.11 TIP2955 0.70
2021944 0.45 2533914 0.45 204036 0.72 205192 0.80 206125 0.47 801080 0.17 0C179 0/5 BC213C 0.15 80338 0.23 002414 0.49 8E173 0.37 BFX30 034 ME6101 0.22 TIP3055 0.59
202195 0.40 293392 0.17 204037 0.60 205193 0.75 40381 0.55 BC109 0.16 BC1794 015 002131 0.17 BC547 0.13 002410 0.65, 01177 0/7 61484 030 ME6102 0.22 11S34 1.05
2021954 0.40 293393 0.17 204058 522 205194 090 40362 0.55 0C1098 0.17 BC1796 025 BC2131.4 0.17 005474 513 802424 0.55 131178 0/7 131485 0.38 MJ2955 1.35 11042 050
202217 0.66 253394 0.17 204059 0.17 205195 017 40383 1.45 BC109C 0.18 BC1790 0.26 6021316 017 805470 0.13 B02420 0.62 81179 0.33 131486 0.30 MJE340 0.62 TIS43 0.47
202218 0.35 2143395 0.19 204060 0.22 295245 0.31 40408 0.82 6C140 0.30 80182 012 BC213LC 517 00548 013 002434 0.65 011130 0.37 81487 0.35 MJE370 0.62 TIS90 0.22
2022184 0.38 293396 0.19 2014061 0.19 2115246 0.38 40409 0.82 BC141 032 801824 0.12 80214 517 80549 0.14 00243C 0.81 61181 0.37 01486 0.30 MJE371 0.86 TIS91 0/7
LINEAR CIRCUITS MICROPROCESSOR SUPPORT TTL & CMOS
013018 0.75 1M379S 425 LM324 0.75 1449300 145
0430184 1.10 LM380N8 0.96 1M78154 1.75 TAD100 2.00 74LS005 0.26 74111625 1.43 74009 0.17 749049 0.45
CA3020 220 LM380514 LM7824K 1.75 184120 090
4K 8 BIT CPU 741S01N 0.26 74151640 1.43 74015 0.17 7491414 0.85
CA30204 2.50 158 LM7810502 104500 224 RAM STATIC 7410025 026 74101680 2.43 74025 0.17 74920 045
£2.04 INS 80804 £7.42
0430284 0.90 1M38145 2.70 0.30 7045000 234 2101-1 STATIC MC 6800 £16.99
7415035 026 74131690 2.43 7403N 0.17 7493N 0.45

2 1 12 £3.377413139
04302813 125 1M381N 1.69 LM781.12C2 184510 2.35 2102-2 £1.94 74100411 0.29 74151740 1.33 74045 0.17 749411 0.90
CA3030 1.50 1M38214 132 030 TBA5100 2A8 RAM SC/MP I £1 2.98 74101011 0.26 74131750 126 74055 022 74955 0.76
21 1 1 £3.37
0430304 220 LM384N 1.55 LM78115C2 TBA520 2.60 TMS 4044/5 MBAR II £10.80 7413125 0.26 741S18114 395 74065 0.56 74969 0.70
043038 2.90 1M3880 098 030 1845200 2.70 ass 74101899 3.74 7407N 055 74975 195
0130384 4.10 1M38711 1.10 MM5314 4.60 TBA530 235 £15.88 741.1149 143 74101905 150 7408N 022 741009 1.46
CA3045 1.55 LM3880 1,00 MM5316 4.60 TBA5300 245 0.26 74131915 1.00 74095 022 741075 035
CA3046 0.77 LM389N 1.00 5E555 0.33 184540 2.60
All prices now 741S2139
741S26N am 741$19251.98 7410N 020 741189 0.95
C43048 245 1007020 091 NE556 585 TBA5400 2.70 RAM DYNAMIC include 16 BIT MICRO 7413279 050 74131935 1.98 74110 026 74119N 1.40
CA3052 1.76 LM709 0.70 NE558N 1.98 TBA550 3.60 4K TMS 4050 £7.43 VAT TMS 9900 £61.50 7410280 0.42 74101969 1.26 7412N 020 741215 028
043080 095 LM7098 0.50 NE560 4.50 7045500 3.80
16K TMS 4116 £36.55 INS 8 9000 £15.00 7410309 026 740005 024 7413N 036 74122N 0.55
C430804 2.10 10070914 0.49 5E561 4.50 T8456000 3.00 7410375 032 740025 024 74140 090 74123N 0.55
CA3086 0.50 LM710 0.67 NE562 4.50 TBA570 210 All Texas 16 bit devices 7413389 032 74C04N 024 7411351 0.36 7412514 0.45
CA30888 1.67 LM71014 0.64 NE565 1.39 1045700 220 are software compatible 7413409 029 740085 024 7417N 0.36 741410 096
CA30896 2.90 LM711C0 0.72 NE566 1.75 TBA7000 220 COMPUTER ON A CHIP. with their 8 bit 741S425 101 740109 024 74200 022 74148N 1.35
0430900 4.40 LM723C 0.75 NE567 1.90 16472045 2.06 The Texas 9980 - £29.89 741.547111 109 740149 1.41 7423N 0.32 741459 0.86
CA3130 1.06 LM723C14 0.45 NE571N 4.95 180750 236 7410489 159 740205 024 74255 032 7415011 1.20
Data 30p
043140 1.04 151726 590 040560 2.70 1647500 2.45 _., rr 74154911 1.09 740300 024 74275 0.32 741515 0.76
1M301 0.30 LM741C 0.70 SAS570 2.70 TBA800 1.30 Na tionalsupporthave r r- , 7410515 0.26 740320 024 7430N 022 74153N 0.76
1003075 0.50 1M741C8 0.30 0A1110 2.10 T1158100 1.30
60 .. ,.. r r 16 BIT SUPPORT 7410540 026 740425 0.9 2 74329 0.30 741545 120
111 3085 0.95 LM741C14 0.30 01:1411 1 35 TBA820 0.00 7415739 0.42 140485 1.38 74375 035 74155N 0.70
1M309KC 115 10074705 0.99 0042P 1.35 184920 299 devices for 8080 £10.85
TMS9901 74137614 0.42 740735 0.54 7438N 032 74157N 078
1003176 335 1117488 0.50 0117600119 104180C 236 Intel have 30 £9.15
TMS9902 7410780 042 740745 0.56 74400 020 7418049 1.10
LM318N 245 LM74814 0.90 1.30 1041606 2.55 - see our new catalogue £7.56
TMS9904 741383411 1.20 740765 0.54 744149 0.114 7416144 1.10
1M32013 2.15 LM1303N 1.15 05760039 701270 299 for a large selection 7410859 1.10 740830.1 1.30 7442N 0.76 7416214 1.10
151320112 2.15 LM13040 1.52 2.38 701730 4.50 UART- TMS6OHNC £5.35 7413905 1.10 740855 1.30 744501 1.40 7416345 1.10
100320115 2.16 LM13055 1.52 S5760135 TCA740 4.50 MM5303 £6.85 7413910 120 740865 0.64 744645 0.90 74164N 1.36
100320024 2.15 LM13075 122
1.1510032015

1M320P12 1.15 LM1351N 1.30

55760235
1.50 TCA750
. TCA760
1.50 TCA105
3.00
2.00
1.49
CMOS ZINGERS
MM74C910 £6.79
VAT Baudrate generator
MM 5307 £13.69
7415920 0.86
74LS93N
74LS95AN 1.10
1.10
740895
74C90N
740935
4.39
0.85
0.65
744740
74485
7450N
090 741650
080 74167N
022 74174N
1.36
2.50
1.00
LM320115 1.15 LM14580 045 00760330 T04440 1.65
MM74C914 £1.41
INCLUDED 8080 Basic Interpreter -i-
7410969 135 74C9501 1.04 74515 022 7417511 120
1M320P24 1.15 1.18149130 0.97 2.35 1041022 750 741310711 042 7401075 122 7453N 022 74176N 090
1003236 6.95 LM18080 2.10 145263 1.35 7041024 124 M M74C9 20 £11.83 IN Hex Debug £72.75 74101095 042 7401505 4.14 7454N 022 74177N 0.90
LM339N 0.60 LM1812N 620 TA4300 3.70 TO41034 4.75 MM74C92 9 f1 1.83 Floppy disc formatter/control 74101220 0.80 74015114 2.47 7460N 022 74180N 1.00
LM340T5 038 100182004 1.16 1443204 1.15 TDA2020AD + 30 others in stock PRICES 8272 £22.00 74101230 0.83 7401545 3.68 7470N 0.46 741815 2.00
1M340115 OM LM1828N 110 1443504 300 4.50 741012411 2.70 7401570 221 7472N 0.30 74182N 0.80
11113411124 0.88 1M18300 190 144521 1.10 U44170 2.15 74101255 0.50 7401605 1.11 74735 0.44 741849 1.50
111341P5 0.80 10018419 1.90 144522 2.10 844180 2.15 74131209 0.50 7401615 1.11 7474N 0.32 74185414 1.50
LM341P12 mop LM18450 1.50 TM550
LM341P15 0.00 10018485 1.98 TAA560
0.48 110807
2.10 1108ICP
125
0.90
4000 0.22 4016 0.52 CMOS 4068 0.21 401313 009
7413136N 0.44
7413145N 130 7401830
74C162N 1.11
1.11
7475N
7476N
0.80
0.45
74188411 325
74189N 2.60
40010 0.22 40170 105 4030 0.84 4050B 0.85 40896 0.24 40898 2.10
IM341024 0.80 I.M1850N 130 TAA570 220 TL082CP 1.10 4002 022 7413151N 1.07 7401640 1.04 7480N 0.60 74190N 1.40
1M3485 055 LM1889N 490 1443704 710830N
4018B 1.05 40318 2/5 40516 0.85 40706 0.35 4093B 1.00
5.45 1.00
4006 1.25 40190 0.52 7413153N 0.58 7401659 1.04 74815 1.00 741919 120
LM3585 0.60 0.60 144630 240 110840111
40356 1.30 40521 016 40716 0.24 4094 2.30
1M3301111 1.45 4007 0.22 40208 1.15 7413154N 1.45 7401735 0.90 74829 0.90 741925 1.20
4037 110 40530 0.98 4072 0.27 4095
LM3605 3.00 LM33025 0.55 144960 3.90 LF355N 020 40080 0.99 ,1.30 741S1555 120 7401749 0.90 74835 1.05 741935 1/0
4021 1.05 40418 0.85 4054 1.40 41738 0.24 4. ..30
M37014 330 LM340111 0.55 744970 420 1.951311 090 4009 0.58 40226 1.00 7413156N 120 7401755 090 748411 120 741969 120
LM371H 2.35 LM39000 0.68 14461113 2.50 LF3575 580
40426 036 4055 1.85 40756 0.24 44009987 41:0069 7741118508,5 04,5 7740401199325, 7744118987,9 2110
4010 0.58 40238 022 4043 1.05 4056 1.65 40766 0.99
11.1171 77448865,N 01;3366

LM3504 6.45 1M39050 1.15 144621 2.50 11132015 100

022 40248 0.76 4044 1.00 4059 6.00 4077 0.70
LM373N 3.35 LM39090 0.78 TAA6614 1.65 1113331540110
3.00
4012 022 40256 022 4045 176 4060B 1.15 4018 027
45106 120 741.016114 0.85 7404959 1114 74999 2A5 741999 2.00
LM3745 3.36 LM3911N 1.10 14466113 1.45 1113741H 080 4511 1.15
40138 0.52 40270 0.55 40466 1.50 4063 1.35 4081B 024 4516 2.10
LM377N
LM3780
1.80 LM7805K 175 TAA700
2.40 LM7812K 1.75 TA49304
4.50 1113741N 055
1.45
4014 1.00
4015 1.05
40280 0.92
40298 1.10
40476 0.96
4049 0.96
40666 0.75
4087 4.85
4082 027
4085 0.89
45188 1.20 NEW LOW PRICES
ell--- Displays 7 se
LEDS + 0 PTO
LEDS Red Gr Yell -,,
NEW 1978
CATALOGUE
DIL SKTS
Low profile IC skts
8 pin 15p
14 pm 111p
16 pin 18p
22 pin 30p
24pin 35p
28 pin 45p
TRIACS
Texas
4 amp
6 amp
8 amp
plastic pack 400v TO2 20
12 amp
72p
77p
82p
93p
16 amp
20 amp
25 amp
£1.21
£1.87
£2.20
4,
Com anode or cath Small 3mm .18 .19 .19 o 40 PAGE CATALOGUE 18 pin 27p 40 pin 55p
iit r.P.
t
blmrd Large 5mm .20 .20 .20 New enlarged micro section -
RED
THYRISTORS
la 8mm HT £1.50 Extra bright .40 .40 .40
10mm HT £1.55 I/red LD2 7 1 £0.55
14mm HT £1.57 IR receiver
1 8mm HT £1.85 Opto coupler £1.55
£1.45
sr '..7,
,
largest range of quality components
from franchised suppliers available
in UK. All VAT inclusive prices.
Over 8.000 line items plus lots
FULL RANGE OF
Capacitors
Resistors
Plugs/skts
Diodes
Cables
Cases
4 amps 8 amps
100v o 38
200v o 44
plastic power
12 amps
100v o 47
200v o 54
100v o 63
200v o 70
1

1.,11 Full range + data in our '78 catalogue

-
more. 45p post paid, 35p to callers Meters in our new 400v o 54 400v o 68 400v o 90
at any of our four branches. Clocks catalogue Branded Texas quality product

VDU
CONVERT TV SET TO VDU
The new CRT control from Thomson CSF
chip
* MAIL * 3+ DIGIT PANEL METER KIT
Intersil
WE STOCK MORE
Stocking distributors officially appointed
SFF9 6 3 64. Convert your TV set into an electronic ORDER T106 kit
VDU - 16 lines x 64 characters - requires RAM,
character generator and little else for a basic VDU. -
Express service on all orders
addoVlaosreders. 40p for P&P
LCD display.
Batt operated.
N EW I '
NATIONAL
TEXAS
VERO
ANTEX
Tel. orders on Contains all components
Available as chip or full display card. Full cursor credit cards El 0 minimum.
control, 5 volts TTL compatible, line reqd for construction MULLARD ELECTROLUBE
erase, full card includes UART.
Modem. char. gen etc.. comp video chip £17.20
NEW 0*.Mr.400
plus PCB. Auto vero
extremely versatile
-.4
-.. SIEMENS SIFAM
out from encoded keybd in. full card £151.00 ,.L.s., VISA and accurate easy SESCOSEM ARROW HART
Send S.A.E. for data.
assembly kit.
£26.99 MAKES COMPONENTS BUYING EASY

Practical Electronics October 1978

 SMALL ADS
The prepaid rate for classified advertisements is 20
CONDITIONS OF ACCEPTANCE
OF CLASSIFIED ADVERTISEMENTS
1. Advertisements are accepted subject to the
conditions appearing on our current advertise-
pence per word (minimum 12 words), box number 60p ment rate card and on the express understand-
extra. Semi -display setting £6.60 per single column ing that the Advertiser warrants that the
advertisement does not contravene any Act of
centimetre (minimum 2.5 cms). All cheques, postal Parliament nor is it an infringement of the
orders etc., to be made payable to Practical Electronics British Code of Advertising Practice.
and crossed "Lloyds Bank Ltd". Treasury notes should 2. The publishers reserve the right to refuse or
withdraw any advertisement.
always be sent registered post. Advertisements, together 3. Although every care is taken, the Publishers
with remittance, should be sent to the Classified shall not be liable for clerical or printers.
Advertisement Manager, Practical Electronics, Room errors or their consequences.
2337, IPC Magazines Limited, King's Reach Tower,
Stamford St., London, S Et 9LS. (Telephone 01-261
5846).

MAINS TOUCH SWITCH KIT. 400 watt load capacity. Details SERVICE SHEETS
free. I. G. BOWMAN, (Dept. PE), 59 Fowey Avenue,
Torquay. S. Devon.
SERVICE SHEETS for Radio, Television, Tape Recorders,
Stereo etc. With free Fault-finding guide, from 50p and
S.A.E. Catalogue 25p and S.A.E. Hamilton Radio, 47
Bohemia Road, St. Leonardo, Sussex.
NOTICE TO READERS
When replying to Classified Advertisements EVERYONE'S A WINNER BELL'S TELEVISION SERVICES for Service Sheets on
please ensure: Radio. TV, etc. 75p plus S.A.E. Colour TV Service
(A) That you have clearly stated your require- WITH CODESPEED Manuals on request. S.A.E. with enquiries to B.T.S.
ments. 19(1 Kings Road. Harrogate, N. Yorkshire. Tel: (0423)
Full Spec. Devices 55885.
(B) That you have enclosed the right remittance.
(C) That your name and address is written in Pack C1 5 x 12 pin Hybrid Circuits each containing 16
resistors/capacitors. Ideal for P.C.B. miniaturisation. FOR SALE
block capitals, and With data. 5 for 50p
Peck DM 1 5 x 14 pin dual in line chips each containing
(D) That your letter is correctly addressed to the 23 quality matrixed signal diodes. With data. 50p SYNTHESISER. Separate Keyboard. Based on P.E and E.T.I
advertiser. Pack E2 A calculator style 8 digit Liquid Crystal display circuits £2511. Riggs, 95 Pickwick Road, Corsham, Wilts.
0.33in high. With data £2.95
Yhis will assist advertisers in processing and Pack E3 Same as Pack E2 but 0.5in high digits. With Phone Corsham 712414.
despatchiAg orders with the minimum of delay. data £4.25
Pack E4 A 11 digit 0.3in high 7 segment gas discharge HARTLEY CT316 Oscilloscope and TE-200 Signal Generator
display. Requires 180V Anode voltage. Makes an together for £50. o.n.o. Phone 021-353 2346.
excellent replacement for LED's in your mains operated
RECEIVERS AND COMPONENTS projects. With full data - fantastic value at only 90p 2 x 61 Note Organ Keyboards complete with contacts
Pack E5 Same as Pack E4, but dual digit. 90p
Pack M1 Terrific value, two calculator keyboards. Only £30.00. Each. Selma]. Clavioline £50.00. Lichfield 24870.
f 1.00
BRAND NEW COMPONENTS BY RETURN Pack M2 1 x 2102. a 1024 bit static RAM. The most ELECTRONIC KITS -SAE for new catalogue, and clearance list
Electrolytic Capacitors 15V, 25V, 50V. popular of all random access memories in professional of obsolete kits. AMTRON U.K. 7 Hughenden Road,
0.47, 1.0, mfds. - 5p.
2.2. 4.7 & 10 and amateur electronics. With full data. £1.25 Hastings. Sx.
22, 47-54p. (50V -6p). 100-7p. 150V -8p1. Pack T4 A 0.8in Giant red LED 12 hour clock display.
2 20-8p. 150V -10p). 470-11p. 150V -10p). Common cathode, 33 digit. An ideal size for your clock
project. With data. £4.95 RADIOSPARES MAINS TRANSFORMERS ex -equipment. Twin
1000/15V --15p. 1000/25V -18p. 1000/50V -22p. Pack T2 Back by popular demand. A high contrast 34 12 volt 4 amp Secondary. Huge saving, only £5.95 post
Subminiature bead tantalum eleetrolytics. digit Liquid Crystal wristwatch display with data. £1.00 paid. .1. Hansom. 12 Torquay Avenue, Hartlepool,
0.1, 0.22, 0.47, 1.0 (04 35V. 4.7 IS 6.3V -8p. Pack P1 1 x MM5330 Digital Voltmeter I.C. With full Cleveland.
2.2/35V & 4.7/25V -9p. 10/25V, 15/16V -12p. instructions on how to build an extremely good digital
22/16V, 33/10V, 47/6V. 68 & 100 6 3V -14p. multimeter or panel meter. £3.95
Mullard Miniature Ceramic [12 Series 63V 2%. Pack M3 Build your own calculator! MM5725 NEW BACK ISSUES of "PRACTICAL ELECTRONICS" available
10 pf. to 47 pf.-3p. 56 pf. to 330 pf.-4p. calculator chi, and cfata 65p each Post Free. Open P.O./Cheque returned if not in
Full 36 60p SN741 55
VerticalMounting Ceramic Piste Caps. 50V. £1 p Sk74170 £1.60 ,trick - Bell's Television Services, 190 Kings Road,
E12 22 pf. - 1000 pf. E6 1500 pf.-47000 pf.-2p. SN Harrogate, N. Yorks. Tel: (0423) 55885.
Polystyrene E117 Series 63V. Hor. Mounting.
10 pf. to 1000 pf.-3p. 1200 pf. to 10000 pf.-4p. )4 1/1.- DEWTRON SYNTHESISER modules 4 oscillators envelope
Satisfaction guaranteed or return complete pee,. for shapers ring modulator 36 note keyboard £70. Also Eagle
Muffled Polyester 250V Vert. Mtg. E6 Series. replacement or refund.
01 to 1-4p. .15, .22-5p. .33, -47-8p. reverb unit £15. Tel: Jarrow 892417.
68-11p. 1-0-14p. 1.5-20p. 2.2-24p. MAIL ORDER ONLY- NO CALLERS PLEASE
Mylar (Polyester) Film 100V. Vertical Mtg. Postage and Packing please add 25p CORE MEMORY PLANES. ex -equip 4K (64 s 64) per plane.
001 002, .005-3p. .01, .02-4p. .04, .05-5p. 99p each + 25p P & P. Eight for £7.50 post free. G. Langley,
Miniature Film Resistors Highstab. E12 5%. CODESPEED :11 Bakers Lane, Woodston, Peterborough.
0.125 watt 100 to 2M20 1p. P.O. Box 23, 34 Seafield Road
0.250 watt 10 to 10M0 (10% over 1M) Copnor, Portsmouth, Hants., P03 58J "RUN YOUR OWN BUSINESS AS AN EXTRA NOME
0.500 watt 100 to 2M70 11:: ACTIVITY. LARGE PROFITS. A GENUINE OPPOR-
1.000 watt 100 to 10M0 P. TUNITY TO SUCCESS." Full details on receipt of
1N4148 -3p. 1 N4002 -5p. 1 N4006 -7p, 1 N4007 -8p. s.a.e. Industrial Supplies. 102 Parrswood Road, Withing-
BC107/8/9, BC147/8/9, BC157/8/9. BF194 & 7-9p. ton, Manchester 20.
20mm. fuses 15, .25, 5. 1.0. 2.0. 3.0 & 5A -3p. TURN YOUR SURPLUS capacitors, transistors, etc., into cash.
Printed Circuit Holders for 20mm. fuses -5p. Contact COLES-HARDING & CO., 103 South Brink, SEEN MY CAT? 5000 Odds and ends. Mechanical Electrical.
Post 10p (Free over £41. Prices VAT inclusive. Wishech, Cambs. 0945 4183. Immediate settlement. Cat free. Whiston, Dept. PRE, New Mills, Stockport.
THE C. R. SUPPLY CO. DIGITAL HEATH KIT Self -instruction course/Tutor,
127, Chesterfield Road, Sheffield SE OR N
PCBs Pasolin 10-1" x ar 4 - £1.25. 12" x 9" 70p. Working. Basics to Microprocessors. £65. Bristol 027-52
Fibre Glass Double Sided 13" x 6" 8379.
171" x 93" £1.15.
VALVES. Radio - T.V. - Industrial - Transmitting and £1.30. 12" x 103" £2.10. Unit with 8 Silicon Diodes
Projector Lamps We dispatch Valves to all parts of the 600V 20 amp. 8 SCRs 400V 16 amp. 6 Vinkors w.w.
world by return of post. Air or Sea mail, 4000 Types in resistors etc. MTh. 300 Small Components Trans.
BOOKS AND PUBLICATIONS
stock, 1930 to 1976. Obsolete types a speciality. List 20p. Diodes £1.30. 7lbs. Assorted Components E2.96.
Quotation S.A.E. Open to callers Monday to Saturday 9.30 List 1 5p Refundable. Post 20p under £1. Insurance add 15p.
tar 5.0(1 closed Wednesday 1.00. We wish to purchase all SIMPLIFIED TV REPAIRS. Full repair instructions
types of new and boxed Valves, Projector Lamps and J.W.B. RADIO individual British sets £4.50, request free circuit diagram.
Semiconductors. COX RADIO (SUSSEX) LTD., Dept. 2 Barnfield Crescent, Sale, Cheshire M33 1 NL Stamp brings details unique. TV Publications, (AUSEPE)
P.W. The Parade. East Wittering, Sussex, P020 8BIN, 76 Church Street, Larkhall, Lanarkshire.
West Wittering 2023 (STD Code) 024366.
THE END OF COMPUTER CONFUSION: what point have we
COMPONENTS, pots, resistors, capacitors, valves, trans- reached - where are we going? Read Computer Lib/
formers, relays - plus lots more. Give away prices. 10p + Dream Machine by Ted Nelson. £5.95 from your Local
RECHARGEABLE S.A.E. for list. Stephenson, Chimney Mill, Newcastle upon
Tv L. (0632) 610210.
Computer Store, or send £6.45 to Computer Bookshop,
Temple House (11.43-48 New Street, Birmingham.

BATTERIES -**),ONENTS. Very competitive

CO
'489 £1.50, -493 35p. Send SAE for list.
EXTENDED RANGE Winstanle Road, Wellingborough, WANTED
HP2 (sae '01 f3.56. HP11 Isire Cl f2.57.Sub C 11-64. Pence!! (sue
i
AA') f1.32. 9 loll PP3 f4-98. 9 volt PP6 (11.66. 9 volt PP7 [9.14. 9 WANTED: Clean new semiconductors, I.C.'s etc. Good
volt PP9 (14.30. All chargers 07.97 (except for PP3 is [582 and pencell prices paid. Hewitts, 52 Barkby Road, Syston, Leicester.
is f6.981 6 volt 8Ah sealed lead acid £11.611. New child's. 2.4 mile
range
ELECTRICAL
ELECTRIC CAR LADDERS
details and lists plus 0.05 ores booklet -Nickel Cadmium
SAE for all
STYLI - illustrated equivalents (List 28) also cartridges,
Power" Add p&p 10%15% ode, £25.00 and oveil All prices include VAT leads, etc. Superb quality and service at lowest prices:
Dept PE. Sandwell Plant Ltd 201 Monmouth Drive, Sutton Coldfield, West Fully guaranteed, Free for S.A.E. from FELSTEAD LADDERS. Varnished 25Ift. Extd. £34.56. Carr. £2.70.
Midlands Callers to TLC. 32 Craven Street, Charing Cross. or to 2 Union
- ELECTRONICS (PE), Longley Lane, Gatley, Cheadle. Leaflet. Callers welcome. Open Sat. Ladder Centre,
Clove. Boldmere. Sutton Coldfield Tel 021-354 9764 Cheshire SK8 4EE. (PEE4) Halesfield (1) Telford, Salop. Tel: 586644.

Practical Electronics October 1978

1116
 SITUATIONS VACANT
PRINTED CIRCUITS
and HARDWARE
Readily available supplies of Constructors' hardware. Printed
circuit boards, top quality for individual designs. Prompt
service. Send 25p for catalogue. From:
RAMAR CONSTRUCTOR SERVICES,

Radio Technicians
Masons Road, Stratford Upon Avon, Warwicks.
Tel. 4879.

ALFAC etch resist transfers and other p.c. board drawing

Government Communications Headquarters has vacancies for Radio Technicians. materials available from stock, s.a.e. details. Ramer Con-
structor Services, Masons Rd, Stratford on Avon. CV37 9NF.
Applicants should be 19 or over

STANDARDS required call for a sound knowledge of the principles of electricity PRACTICAL ELECTRONICS P.C.B.'s
M glass fibre tinned and drilled
and radio, together with appropriate experience of using and maintaining radio Dec. 7 7 Car Burglar Alarm 1412-1 88p.
Ma 78 Moving ht Disla
and electronic test gear. Mayy 78 Workshop Power p Supply £1.97.
May 78 Chorus Generator £2.55.
July 78 Dimwit £1.48.
DUTIES cover highly skilled telecommunications/electronic work, including the Aug 78 Touch Switch 85p. C.W.O. Please.
For full list and current boards please send S.A.E.
construction, installation, maintenance and testing of radio and radar P.C.B.'s also produced from customer's own master -
telecommunications equipment and advanced computer and analytic machinery. please send for quote.
PROTO DESIGN
14 Downham Road, Ramsden Heath, Billericay, Essex
QUALIFICATIONS: Candidates must hold either the City and Guilds
Telecommunications Part 1 (Intermediate) Certificate or equivalent HM Forces
qualification. ELECTRONIC KITS. A company serving the amateur
electronics market is interested in purchasing electronic
kits to widen its range. Companies selling such kits are
SALARY (inc. supps.) from £2,927 at 19 to £3,700 at 25 (highest pay on entry) invited to contact: Box No. 75.
rising to £4,252 with opportunity for advancement to higher grades up to £4,706
with a few posts carrying still higher salaries.
Opportunities for service overseas.
LOST THE TIME?
MSF 60 KHz RECEIVER, built-in antenna,
Further particulars and application forms available from: £13.70, or with parts (no case or pcb) for
sequential YEAR, MONTH, DATE, DAY, HOURS,
MINUTES, SECONDS display £24.40.
GCHQ MISSING LONG WAVE? NEW 200 KHz to
Med. Wave Converter, built-in antenna, inductive
(place near receiver) and coax outputs, £9.70.
Recruitment Officer, (Ref PE/10) PROGRAM YOUR OWN tunes on a MUSICAL
GCHQ, Oakley, DOORBELL, new jingle every day, just needs bell
transformer and speaker, £19.50.
Priors Road, Cheltenham, GL52 5AJ. Each easy -assemble kit includes all parts, printed
Cheltenham (0242)21491 Ext 2270 circuit, case, postage etc, instructions and money
back assurance so SEND off NOW
CAMBRIDGE KITS
45 I FK) Old School Lane, Milton, Cambridge

SUPERB INSTRUMENT CASES BY BAIELLI, manufactured

from P.V.C. faced steel. Hundreds of people and indus-
trial users are choosing the cases they require from our
vast range. Competitive prices start at a low 90p, chassis
punching facilities at very competitive prices, 400 models
to choose from, free literature (stamp would be appreci-
ated). BAZELLI, Dept: No. 23, St. Wilfred's, Foundry
EDUCATIONAL MISCELLANEOUS Lane, Halton, Lancaster. LA2 6LT.

MAKE YOUR OWN PRINTED CIRCUITS

100 WATT GUITAR/PA/MUSIC Etch Resist Transfers - Starter pack (5 sheets, lines,
COLOUR TV SERVICING pods, I.C. pads) £1.30. Large range of single sheets
Learn the techniques of servicing Colour TV sets AMPLIFIER
With superb treble, bass. Overdrive, slirraine. 12 months in stock at 27p per sheet.
through new homestudy course approved by leading guarantee. Unbeatable offer at £39. Also twin channel with Ferric Chloride llb bags 80p (P&P 40p)*
manufacturers. Covers principles, practice and align- separate treble/bass per channel £48. Money returned if not Master Positive Transparencies from P.C. layouts in
ment with numerous illustrations and diagrams. Other absolutely delighted within 7 days. Also fuzz boxes great magazines by simple photographic process. Full in-
sound robust construction f8.80. Also 100 watt 12 in.
courses for radio and audio servicing. Full details from: speakers £22.50. structions supplied. 2 sheets (20 x 25cm) negative
All inclusive of P.P. Send cheque or P.O. to: paper and 2 sheets (18 x 24cm) positive film £1.20.
ICS SCHOOL OF ELECTRONICS WILLIAMSON AMPLIFICATION S.A.E. lists and information. P&P 20p/order except*
()sit. 272Z Intertext House, London SW841.3
Tel. 01-622 9911 (all hours) 62, THORNCLIFFE AVENUE, DUKINFIELD, P.K.G. ELECTRONICS
CHESHIRE. TEL: 061-3445007 OAK LODGE, TANSLEY, DERBYSHIRE
State if under 18

SINTEL FOR BOOKS, CMOS AND COMPONENTS

CLEARING LABORATORY. Scopes, recorders, testmeters.
bridges, audio, R.F. generators, turntables, tapeheads,
TECHNICAL TRAINING stabilised P.S.U.s, sweep generators, test equipment, etc. 6800 Booklet 1.80, MOT CMOS Databk 3.50, 6800 Appl
Lower Reeding 236. Mon 12.95, 6800 Prog Mon 5.35, SC/MP Introka Mon 0.75
Get the training you need to move up into a higher NS TTL Dotabk 2.10, RCA CMOS Dotobli 5.45, 8085 User s
paid job. Take the first step now-write or phone ICS Mon 5.15, Z80 Ass Long Prog Mon 7.50, Z80 CPU Mon
for details of ICS specialist homestudy courses on 5.60, Z80 CTC Spec 0.80, Z80 PIO Mon 3.30. Also a full
Radio, TV, Audio Eng. and Servicing, Electronics, MORSE CODE TUITION AIDS range of CMOS - send for free catalogue MPUs:
Cassette A: 1-12 w.p.m. for amateur radio examination.
Computers: also self -build radio kits. Full details from: Cassette B: 12-24 w.p.m. for professional examination pre- ME K 6800D2 205.20, MC6820 7.50, Z80 18.14, Z80A
paration. 24.19, Z8OCIC 10.96, Z8OPIO 10.96, Memories: 2102-A
ICS SCHOOL OF ELECTRONICS Morse by light system available. Morse Key and Buzzer unit 2.00, 2112A-4 3.13. Displays: Type END%) C.C. 1.40,
for sending practice. Type TIL321 C.A. 1.40, 5001 5.29. Crystals: 32 768K1-tz
Dept. 272Z Intertext House, London SW841..3 Prices each cassette (including booklets) £4.50. Morse Key
Tel. 01-622 9911 (all hours) and Buzzer E4.50. 3.19. Clock ICs: AY5I202 3.35, AY51224 3.73, MK50253
Prices include postage etc., Overseas Airmail £1.50 extra. 5.83. Soldercon Pins: 100 0.54, 1000 4.32, 3000 11.34.
State if under 18 Free catalogue by return. All items CWO. Prices inclusive of
MHEL ELECTRONICS (Dept. PEI VAT. Add 35p p&p. SINTEL, P.O. Box 75B, 209 Cowley
12 Longshore Way, Milton, Road, Oxford. Tel. 10865149791.
Portsmouth PO4 8LS.
CITY & GUILDS EXAMS
Study for success with ICS. An ICS homestudy course
will ensure that you pass your C. & G. exams. Special BEST OFFER EVER £99.99 TTV,P810- TV CAMERA
courses for: Telecoms. Technicians, Electrical Complete TV Camera Kn for under E100.00 le xcluding P/P and VATI. Offer
Installations, Radio, TV & Electronics Technicians, includes Lens, Tube and FREE Modulator. Plugs directly into AE socket of TV or
Radio Amateurs, Full details from: VCR. Reliable high performance design. Suitable for Security, Education, Industry
etc. Fully compatible with other CCTV Equipment. Fully Guaranteed Parts. Buy ,t
I('S SCHOOL OF ELECTRONICS with your Credit Card.
Dept. 272Z Intertext House, London SW84UJ
Tel. 01-6229911 (all hours)
State if under I8 CROFTON ELECTRONICS LIMITED
35 Grosvenor Road. Twickenham, Middlesex TVV1 4AD Tel 01-891 1923

Practical Electronics October 1978 I I I 7

 DEAD or ALIVE NO LICENCE EXAMS NEEDED
To operate this miniature, solid-state Trans-
OR JUST mitter -Receiver Kit. Only £9.75 plus 25p
MIXED UP?
5 -FUNCTION -4/ 'i`
P. & P.
'Brain -Freeze' em with a MINI -STROBE
Kit, pocket -sized lightning flashes', vari-speed,
NOTICE
13 AMP- for discos and parties. A mere £4.30 plus 20p
P. & P. Experiment with a psychedelic
DREAM LAB, or pick up faint speech/sounds

TESTER-,\
with the BIG EAR sound -catcher; ready-made
multi -function modules. £5 each plus 20p
P. & P.
TO
SAFELY SHOWS YOU! \N LOTS MORE! Send 20p for lists. Prices include
VAT. (Mail order U.K. only).
Safety fast! Shows: I, If all wires correct.
2, Live wire faulty. 3, Live and Neutral wires
reversed. 4, Earth faulty. 5, Neutral faulty.
Shows exact fault instantly. British made.
£3.95 post free. Save time. Be sure. Be safe.
BOFFIN PROJECTS
Cunliffe Road, Stoneleigh
READERS
Ewell, Surrey (P.E.)
PERSONAL SAFETY CO.,
Dept. PEI, P.O. BOX 1, Whilst prices of goods
LLANRWST,
GWYNEDD, NORTH WALES
PRINTED CIRCUIT BOARDS made to your requirements.
Write for details and price list. Western Circuit Designs. shown in classified
'11 Great Hinton, Trowbridge. Wilts. BA1 4 6BY.
advertisements are
BUILD THE TREASURE TRACER
-
BELLS AND SIRENS
CARTERS SIREN
,...(CE-Di
correct at the time
MK III Metal Locator INDUSTRIALSI SIX£553
BELL £827
INCH
of closing for press,
0 PRICES INCLUSIVE
Send Cheque, P.O. to:
14.1' l.'

readers are advised

Vanua Wonni CWAS ALARM
OW soling mod locator nt 11 Denbrook Walk, ....,"
,.... se
'mod rots Faraday ahnyld
Speaker and aarphon oparalion
es already sold 6 to 12v D.C.
Bradford B D4 OQS.
SAE for full Price List of
Nk...,_

12v D.C.
to check with the ad-
Probult1 wren coil enbly
in* tramcar 0ircuil
Professional Burglar Alarm Equipment
vertiser both prices
and availability of
T.V.duriBlY Volmlonal Inman
vu ore,/ need aoldanno won acre.
dno., altars and snips
As **an on BBC-, and OBC-2 TV
THE FABULOUS
Send "mood aad.osaad
for 1000,
forroo100*
D2 MICROPROCESSOR goods before order-
Complete £15.95tesled n0 £20 95 EVALUATION KIT ing from non -current
ft 37 VAT Post fl 20 (1 77 VAT
Post t 1 20
MINIKITS ELECTRONICS 6g CLEVELAND ROAD
FROM MOTOROLA. issues of the magazine
LONDON EIS 2AN I Mall Order Only)
Featuring *24 key keyboard *Seven segment
TRANSFORMER PROBLEMS? display *Cassette interface *Erom & Ram
Expandable *Interface Capability *Full
Send SAE with requirements for return of Documentation *5 Volt power supply Required
post quote. *One years FREE membership of The Amateur
Computer Club with every purchase*. £176 +
TRENT, TRANSFORMERS LTD
f1.50 P & P + 8% VAT.
Chapel Street,
Long Eaton, Nottm. 06076 66716
INCREDIBLE WATCH
ENAMELLED COPPER WIRE BARGAINS
SWG I lb 8 oz 4oz 2 oz .'411818111111$41
NEW 10-19 2,60 1.40 .66 .55
ODIK MK 2 in -circuit junction tester. 20-29 2.80 1.60 .85 .65 12 FUNCTION
Tests all silicon and germanium 30-34 3.013 1.70 .95 .70 CHRONOGRAPH
transistors (inc. power types) without 35-40 3.35 1.90 1.10 .79
LCD
desoldering from the circuit. Also tests 40-43 4.50 230 1.90 1.25
diodes. S.C.R.s and L.E.D.s. 2.10
hours, minutes, seconds, day
44-46 5.00 3.00 1.65
* Simple to use. 47 8.00 5.00 3.00 1.76
date, month, chrono time Loth
* Go - No - Go indication. 15.00 9.00 6.03 3.30 sec. 2 event timing, 1st and 2nd
48
* Full instructions for use. place times. non interrupt be-
* Robust. tween chrono and real time
Tinned Copper, Even Gauges 14-30 £3 per lb. backlight.
Comes ready to use with battery fitted.
Multicore 60/40 Solder 18SWG £3.24 per lb.
Price only £7.95 inc. P. & P.
Prices include P & P and VAT'.
REVOLUTIONARY SAE brings list of copper and resistance Wires.
MULTI -PURPOSE TESTER
A MUST FOR EVERY HOME AND WORKSHOP.
testtl
aCpapnliabencueses fdorlcoonr, fuses, filament lamps and electrical
THE SCIENTIFIC
* Tests High Resistance
items (i.e. Low wattage
appliances)
WIRE COMPANY ALARM LCD
* Simple to use. PO Box 30 London E.4. sin digit hours minutes optional
Reg. Office, 22 Coningsby Gdns.
* via- No - Go indication seconds or date, month, date,
via Space age L.E.D. day/4 year calendar, alarm pro-
* Battery supplied. odik grammable for any minute in 24
* Absolutely invaluable to
the handyman, amateur
RADIO hours with on/off indication,
backlight.
and professional. CONTROL
Price only £2.50 Inc. P & P.
VERSATILE
THE ODIK MULTIVO LT
micron SPECIALISTS
Kits for multi channel
systems. Special parts
ri
and accessoes.
A General purpose power
supply providing 4 switchable S.A.E. FOR LEAFLETS
output voltages from a mains Tel: 0602 395418
input. Suitable for the
majority of radios. cassette MICRON R/C, Hayworth Road, STOP PRESS
players and other battery
powered appliances. May also Sandiacre, Nottingham. FULL CHRONOGRAPH/ALARM LCD
be used as a step down
transformer to power a model ONLY £39.95
train etc.
* Provides 12v. 9v. 7.5v. and 6v outputs. CABINETFOR
FITTINGS All prices include presentation case, 12 month guarantee
instructions, P& P. Vat. Money back guarantee.
* Regulated output provides up to 400mA.
* Attractive, Robust METAL enclosure. Stage Loudspeakers and Amplifier Cabs Send cheque of P.O. to
* Supplied with output lead together with 2.5mm and Fretcloths, Coverings, Strap 8. Recess Handles, Feet, Castors,
3.5mm power plugs. Jacks & Sockets, Cannons, Bulgin 8 ways, Reverb Trays,
Locks 8. Hinges, Corners, Trim, Speaker Bolts etc.
VIDEOTIME PRODUCTS
Price only £6.95 inc. P&P. 56 Queens Road, Basingstoke
Send 2 x 9p Stamps for samples and illustrated catalogue.
DIRECT FROM THE MANUFACTURERS Hants RG21 IRE. Tel. (0256) 56417
ADAM HALL (P.E. SUPPLIES) Telex 858747
ODIK ELECTRONICS
43, Meadowside. Nuneaton, Warwickshire
Unit 3, Carlton Court, Grainger Road
Southend-on-Sea, Essex.
Trade & Export Enquiries Welcome

1 1 18 Practical Electronics October 1978

 SCREENED MINIATURES COMPONENT PACKS AMPLIFIER MODULES
Ref mA Volts £ P&P 50 High Quality Metal Oxide E3-75
TRANSFORMERS
10W IAL301
238 200 3-0-3 1 99 0 55 2.5% w Resistors. 25W IAL601 £4.57
212 1A, 1.4 0-6, 0-6 2 05 0.78 150 Mixed Value Capacitors 35W IAL801 f715
13 100 9-0-9 2 14 0.38 10 Read Switch. 125W (AL250) £1725
ALL EX -STOCK -SAME DAY DESPATCH. VAT 8% 235 330, 330 0-9, 0-9 1 99 0 38 30 Wire Wound Resistors, Power Supply PS12 f130
207 500, 500 0-8-9-, 0-8-9 2 59 0 71 mixed. Power Supply SPM80 £4.25
120R 24 VOLT OR 12-0-12V 30 VOLT RANGE 208 IA, IA 0-8-9, 0-8-9 3 53 0 78 25 assorted Presets. Pre -amp PA12 £6.70
Prim 220/240V Sec 0 12 15 20 24 30V. 236 200, 200 0-15, 0-15 1 99 0 38 50 3 Tag Terminal Strips. PA100 £13.88
PRIMARY 220-240 VOLTS 214 300, 300 0-2C, 0-20 2 56 0 78 Hardware pk. bolts, nuts. .-xt P k P 115,
AMPS
Voltages available 3, 4, 5, 6, 8 9, 10, 12,
15, 18, 20, 24. 30V or 12V -0-12V, 221 700 (DC) 20-12-0-12-20 3 41 0 78 washers, insulators. All 70p ABS Plastic Boxes brass
Ref 12V 24V £ P&P 15V -0-15V. 206 1A, IA 0-15-20-0-15-20 4 63 0 96 each + 12-1% P & P 40p.
111 05 025 220 045 203 500, 500 0-15-27-0-15-27 3 99 0 96 Puts, slots to take PC cards, flush
Ref Amps P&P lilting lid.
213 10 05 2 44 0 78 112 05 264 078 204 1A, IA 0-15-27-0-15-27 5 39 0 96 12 way Grelco heavy black 56p
71 2 1 3.51 0 78 S112500 12-15-20-24-30 2 84 0 78 plastic terminal block 35p P81 80mm x 62 x 40
79 1 0 3 57 0 96 PB2 100mm x 754 40 83p
18 4 2 4 03 096 3 20 527 096 239 50 12-0-12 1 li 0.38 P & P 15p. PB3 120mm x 100 x 45 70p
70 6 3 5 35 096 20 30 6 20 14 Fuse holder 14" completely P & P 29p VAT R
108 8 4 6 91 1 14
40 7 44
1
MINIMULTIMETER
72 10 7 67 1.14
21 1 14
DC -1000V AC -1000V DC-100mA Res -150k0 enclosed 25p P & P 15p. Magnetic to Ceramic. L,ippdge
5
51 50 837 1 32
2x Fuse boards - 2 with
116 12 6 B 99 1 32 117 60 9 92 1 45 10000/V Bargain E5436.P & P 62p VAT 8% Convertor operating voltages 20-
17 16 10 39 1 32 88 80 11 73 op + holde 45V only £3.50.
1 64 20,000 ohan/V Multimeter, mirror scale. Ranges
115 20 10 13 11 2 08 89 10 0 13 33 184 21"en x 3"1 30pfu Pse & P 15prs VAT 12+3, P & P 35p.
187 30 15 17 05 208 AC/DC to 1000V, DC currents to 250mA.
226 60 30 26 82 OA 60 VOLT RANGE Resistance to 3 Megs. 5" x 31" x 11" NEW RANGE TRANSFORMERS TRANSFORMERS
Prim 220/240V Sec 0-24-30-40-48-60V. £11.34 P&P El .05 VAT 8%. Special Offer
50 VOLT RANGE Voltages available 6. 8, 10, 12, 16, 18, 20, P&P
Prim 220/240V Sec 0 20 25 33 40 50V TEST METERS 45-36-0-36-45. 2A 9.89 1-38 B EI Prim 0-120,
24, 30, 36, 40, 48. 60V or 24V -0-24V,
Voltages available 5, 7, 8, 10. 13, 15, 17 30V -0-30V. U4315 Budget Meter 20KO/V DC 2K/V AC to give 3A 1147 1.48 0-120V (120 or
20, 33, 40 or 20V -0-20V, 25V -0-25V. 1000V AC/DC 2.5A AC/DC 500K res, in robust 36-0-36, 4A 13.90 1.84 240V) Sec 24V 10A
Ref Ref Amps £ P&P steel case and leads £15-85. 45-0-45. 5A 18.74 2.15 ES 50 P & P £1 66
Amps P&P 05 367 0.96
102 05 3 41 0-78
124
BX505 Sanwa f33.88 TT169 circuit transistor 72V or 90V. 6A 20.77 230 PW Scope 250-0-
103 10 4 57 0.96 126 1 0 5 50 098 AVOB £77.10 tester £3250 VAT 8% 250V. 6.3V, 12 9-
127 20 7 60 1 14
AV071 £31.10 DA116 digotal £100.00
104 1 14
125 30 10 54 32 PLUG IN SAVE BATTERIES 0-12.9V.
105 30 II 45 1 32 40 12 23
1
AV073 f42.50 Megger BM7 £6.50 P & P 90p.
106 40 10 70 50
123 1 84
EM272 f5070 Battery £42.50 MVA 30 - fits into 13A Ski. 6, 7.5,
107 60 14 62
1

64
40 50 13 95 1 64 MM5 £26.10 Wee Megger £64.00 9V 300mA multiplug outlet £330. B E3 100V line to
118 80 17 05
1

208 120 60 15 66 1 84 MVA 36 - 13A Skt. 3, 4.5, 6V @ 40 7/10W £205

121 80 20 15 OA P&P E 1.15 VAT 8%. 100mA multiplug outlet £330. P 6 P 660
119 10 0 21 70 OA 122 100 24 03 OA Full range of AVO's, Megger's and Cases. A122 - 3, 4.5, 6, 7.5. 9, 12V
189 12 0 27 13 OA B E4 0-120V x 2
MAINS ISOLATING (SCREENED) Special Offer AVO Meter (107) 500mA multi plug outlet £9.21 (120V or 240) Screen
PRIM 120/240 SEC 120/240 CT TAPPED
Ref VA (Watts) £ P&P AUTO TRANSFORMERS Ranges DC volts 2.5. 10, 50, 100. 500, 1000V - VAT. 12 PE P & P 55p. sec 9-0-9V 1A
current 1mA, 2.5, 10, 50, 100. 500, 1 amp, AC DECS SOLDERLESS £240 P & P 71p
07. 20 4 40 0 79 Ref VA (Watts) £ P & P 10V, 100, 1000, 3 ohmic ranges to 10M ohms.
149 60 6 20 0.96 '113 15 0-115-210-240 2 41 0 71 BREAD -BOARDING 13E5 15W matching
75 0-115-210-240 0 96
10,000N DC, 1000 AC Safety cut out £40-00 S Dec 70 contacts El 98 trans sec 150 suit
50 100 7 13 1.14 64 3.95 P & P £1.15. VAT 8%. EL89 E1 50 P 5 P
151 200 11 16 1.50 4 150 0-115-200-220-240 5 35 0 96 T Dec 208 contacts E3 63
152 250 12 79 1 84 67 500 0-115-200-220-240 10.99 64 U Dec "A" for I.C.s etc E3 99 30P
153 350 10 20 184 84 +000 0-115-200-220-240 18 76 2 08
1
ISOLATOR 1KVA 240V to 240V enclosed U Dec "B" for I.C.s etc £6.99 B E6 PRI 0 220V sec
93 1500 0-115-200-220-240 23 36 OA Special OfferTg £1870. Carriage £2.75. VAT g% P & P 40p 4500V tO M A £4.50
154 500 19 15 2.15
OA 95 2000 0-115.200.220-240 34 82 OA P6 P C1.00
155 750 29 06 ELECTRONIC CONSTRUCTION KIT A NTEX SOLDERING IRONS 6E7 0-110-120
156 1000 37 20OA 73 3000 0-115-200-220-240 48 00 OA 10 projects (including electronic organ). No 15W £375 ST3 - Iron safety
157 OA
45 60 80S 4000 0-10- 115-200 soldering needed £7 29. VAT 8% P 6 70P 220V Pri 240V
1500 25W £3.95 stand £140 Sec 20V 1A £1.50
158 2000 54 80OA 220240 67 50 OA P & P 48p VAT 8%.
159 3000 OA
79 05 PANEL METERS 30p P & P.
Please specify 115 or 240V required
CASED AUTO TRANSFORMERS 2'0-500A 5.50 4" 0-50pA 6-70 BRIDGE RECTIFIERS Ref 30 240-240
240V cable in & 115V USA 2 pin outlet 50V 50A £2.00 Isolater 200VA
VA £ P&P Ref
0-500pA 5-50 0-500pA 6.70 Carriage E045
0-1mA 5.50 0-1mA 840 200V 2A £4.20 P & P 96p.
HIGH VOLTAGE ISOLATORS 15 496 0 96 113W 0-50V 400V 4A £085 240-240
Prim 200/220V or 400/440V 150 9 48 14 4W 5.50 0-50V 8.40 65P Ref 62
1
0-100pA 5.50 0-1006A 870 VAT BO 400V 6A E1.05 Isolators 250VA
Sec 1 10/120V CT or 200/240 CT 200 9 92 1 45 65W "VAT 8% 15p P&P Efi 20 P & P 96p
250 10 49 1'45 69W VU Indicator Panel 48 x 45 250pA FSD
Va Ref P&P £260
60
350
1000
243
247
250
5 89 1 32

14 11
41.76
1

OA
84
500
750
1000
15 73
11 55
23-50
1 64
1 OA6
7
67W
83W
84W
VU Indicator Edge 54 x 14 250pA FSD
£2.60
Barrie Electronics Ltd.
2000 252 54 25 OA
1500 29.02 OA 93W
Prices correct 17.8.78. Please add VAT 3, THE MINORIES, LONDON EC3N 1BJ
2000 37 65 OA 95W
after P. & P. PE1 TELEPHONE: 01-488 3316/7/8
57S 5000 0-10-115-200- Our wide range of transformers are too numerous to list. Please call (open 9am-5pm Mon-Fril
220-240 7748 OA or send your requirements. Electrosil & semiconducto stockists. Audio accessories. NEAREST TUBE STATIONS: ALOGATE & LIVERPOOL ST

PROGRESSIVE RADIO
93 DALE STREET. LIVERPOOL L2 2JD. Tel: 051-236-0982
SEMICONDUCTORS ALL FULL SPEC. BC212, BC182, BC237, BF197, BC159 all 8p each
LM380 80p. LM387 95p, 741 8 PIN 23p. 741S (wide bandwidth) 8 pin 35p. TIL305 Alpha
New from Mantec
numerical display (with data) £250p. BX504 opto isolators infra red led to photo cell, 4 lead 25p,
BFY50 plastic 14p, STC 3 volt 1 watt zener diodes 7p each. BD533 33p, MRD3051 photo A comprehensive Home Study Course in
transistors 35p, FETS similar to 2N3819 18p, MOSFET similar 40673 35p. Intel C1103 1024 bit
mos rams 95p, CD4051 45p, 723 14 pin I.C.15 35p, Electronics
DIODES, BY127 9p, IN4002 4p. IN4005 7p, 600v 3 amp 17p. Lucas bridge rocs, 400v 1 5
Suitable for Beginners and Students
amp 30p. SPECIAL OFFER. TBA800 10 for £5.00. NE555 10 for £3.00.
MAN3A 3mm led displays 50p, MM. Nixie 587 OST 75p. The Course which gives you "Right from the
Pot core unit, has six pot cores including one FX2243 (45mm) and two FX2242 (35mm) 3 103 sil
power transistors on heat sink, 3-20mm panel fuseholders and panel with various transistors Start" the practical experience as well as the all
diodes and a 5 amp plastic SCR. £1.75p plus 75p postage.
MOTORS, Model type 1.5-6 volts 20p, 'BIG INCH' sub min motor 115 vac, 3 r.p.m. 25p. 24
important back-up theory.
OVAC SYNCH, MOTORS WITH GEARBOX, 1/5 r.p.m. 75p. 1/24th r.p.m. 75p, 15 r.p.m. £1.20p, Suitable preparation for C and G examinations
Crouzet 115 VAC 4 r.p.m. 95p, 12v dc 5 pole 35p.
HI -SPEED MORSE KEY. ALL METAL £2-25p. PLASTIC MORSE KEYS. 95p.
Ensure your future in tomorrow's technology
PLESSEY WINKLER SWITCHES, 1 pole 30 way, 2 bank adj. stop 75p.
Crystal microphone inserts 37mm 45p, Grundig electret condenser inserts with built in FET The home study course that tells not only how but why
preamp El .50p. ELECTRET PENCIL HAND MICROPHONES 1K IMP WITH STANDARD JACK The Course includes:- 1 The Manual. Easy to
PLUG f 2.85p, TIE CLIP CONDENSER MIKES OMNI, 1K IMP, (uses deaf aid battery, supplied)
£4.95p. read and understand, set out in a clear and
SOLDER SUCKER, high suction, eye protection shield f4.95p. concise way, includes numerous
PROJECT BOXES, BLACK ABS PLASTIC WITH BRASS INSERTS AND LID, 75 x 56 x 3544p.
95 , 71 x 35 52p, 115 x 95 x 36 150p. experiments and diagrams. y.
BUZZERS, GPO open type 3-6v 30p. Large plastic domed type loud note 6 or 12 volts 50p, Solid 2 The Kit. All components
State buzzers, miniature, 6-9-12-24 volt 15ma 75p each.
TAPE HEADS, Mono Cassette E1.30p. Stereo cassette £3.00, BSR MNI330 half track dual in -
necessary for the experiments
red. heads £175p, TD10 Dual head assemblies 2 heads both + track R/P with built in eras:. and projects covered. Mantec also provies
mounted on bracket, £1.20p.
Relays, Min. sealed 12v dc type 4 pole changeover 55p, Min. 24v dc 2 pole do 3 amp contac, a tutorial support service for students requiring further advice.
55p. Min sealed 220v ac 2 pole c/o 40p. Open type t 2v dc 4 pole do 50p, 4 pole reed relays N 0
20p.
Send today for your "Right from the start" Home
CRYSTALS, 300khz 40p. Aerosol 'Touch up' paint one colour yellow/grey. 6oz can 35p. 50v ac
cam units. motor switching ten c/o micro switches, supplied with capacitor for 240v ac use
Study Course. Price £35.00 including VAT.
£1.95p plus 35p postage.
Belling Lee L4305 masthead amplifiers and mains power unit, new but only for group A UHF
Fill in the coupon Now!
E7 -50p. Mantec the leaders in Manufacturing Technology 1
TRANSFORMERS, 6-0-6v 100ma, 9-09 75ma, 12-012 50ma 75p each, 12-012 100ma 95p. Mantec, 7 Dellsome Lane, Welham Green, Hatfield, Herts.
12v 500ma 95p, 1:1 triacixenon pulse transformers 30p, CHOKES 6MC 3 Amp 20p. U.H.F.TV mi im imin moo mom ime
Tuners, push button (not varicapl new and boxed £2.50p. Miniature toggle switches, SPST 8 x 5
x 7 45p, DPDT 8 v 7 x 7 50p, DPDT c/o 12 x 11 >i 9 75p, Min. push to make or push to break
16 x 16mm 15p each type. Slider switches, DPDT standard 15p, MM. 12p, Std. c/o 20p. Roller rTo: Mantec, 7 Dellsome Lane, Welham Green,
action micro switches 15p.
TOOLS Small side cutters 5" insulated handles £135p. Snub nosed pliers 5" insulated handler Hatfield, Herts.
£l -35p. Watchmakers screwdriver sets, 5 drivers in wallet £1-00p. Large mains test,
screwdrivers, fully insulated 8" 44p. Test lead jumper sets, 10 leads with insulated trot clips ea,.
I Please send me "Right from the Start" home I
end, different colours 80p. Telephone pick up coil, suction type with 3.5mm jack plug 50p. 9 voIT
battery eliminators, 240v ac input 9v dc out at 120 mA, stabilised replaced PP3, PP6, PP7,
Istudy courses).
E2 -45p. Edge connectors. 0.1 64 way 86p, 34 way 4 op, 0.2 18 way 15p. Murata MA401 I enclose Cheque/ Postal Order for £
40KH2, Transducers Rec/Sender, f3.25p pair. Tape head demagnetisers, 240v ac with or,o'
switch, straight probe moo, curved probe (cassette) f2 -35p. I Name:
TERMS: cash with order, (of official orders from colleges etc). Postage 30p unless otherwl,,
shown, overseas post at cost. VAT inclusive prices S.A.E. for lists. Address:
Progressive Radio, 31 Cheapside. Liverpool 1.2 2DY. Tel: 051-236-0982.

%%IUD 11 =1111 RIM =SI 9999.

Practical Electronics October 1978 1 I 19

 TTLe81TEXAS LINEAR 1Ca MCI495 600p TRANSISTORS BF751/2 22p TIP41C 760 213823 70, 01008 BRIDGE
7400 13p 74116 200, 74368 1500 9302 1754 4015 84p *051 0212 5009 *MC1498 100p 001275 20p 048156 33p 11P424 700 2143666 SOP *61127 12p 5503391555
7401 14, 74118 1300 74390 2000 9308 3160 4016 459 411 1313 6801 '18C3340 160P 60149 700 8E990 90p T11420 52p *253903/4 14 %%47 911 *IA 501 Zip
7402 14p 74119 214 74393 204 9310 274 4017 84'4115050 212p *M03360 OOP 40161/2 44 BLVD 704 1112955 710 '283905/8 24 ..0081 150 *14 100V 22p
2403 14 74120 114 74490 224 9311 2150 4018 89p 0r5 1315 600p *MFC40000 1200 6C107/13 114 89939 45p TIP3055 74 *2014036 14 '046 15p *IA 4009 34
7404 17p 74121 26p 9312 164 4019 45p 'AY5 1317 636, 841503913 754 BC109 110 00019/20 20p *T1543 34p '214050/9 12p '0090 9P '201 50V 30p
7405 16, 74122 410 741SSERIES 0314 165p 4020 100p *495-1320 320p NE531 13% *0C147/8 1p 110105 194 *UX108 12p '2144060 12, 0491 99 *24 100V 354
7406 320 74123 550 741000 224 9316 225p 4021 110p '1A3019 10, '148540 20011 *BC149 lip '0411108 25Dp *ZTX300 13p '214061/2 11, '0495 911 '2A 400V 459
7407 329 74125 55p 741002 22p 9322 150p 4022 100p *CA3046 70p 1405431 2259 *0c157/8 10, '14U205 2201 ./11500 15, '214123/4 220 '04200 9P *34 2009 615.
7408 14 74128 60p 741004 220 9368 2001 4023 22p *043048 224 50555 5011 '60159 lip '0U208 204 '211602 114 *214125/6 220 n In%
%Am,. lop '34 800V 729
7409 14 74128 76, 741406 22p 9370 200p 4024 55p CA30800 72p 8E550 70p *E1C169C 12p *E4408 1450 '110504 30p *2144401/3 27P '18914 4p *44 100V 160

50pTRIALS
7110 14 74132 74 741010 214 9374 200p 4025 201 *C43089E 2250 NE5616 425p '8E172 12p MJ481 175p 254516 2504 7044427 84 15918 7P *4 4009 100,
7411 240 74136 75p 741013 454 9601 100p 4026 1114 CA30900.0 3750 1405020 4259 80177/8 17p MJ491 200p 20898 301 *2144871 600 *154148 4 64 50V 40
1412 24 74141 74 74014 1000 9602 175p 4027 50p 003130S 100p 8E565 1300 BC179 18p .
4472501 225p 20697 254 *2045087 27P 114001/2 5p 60 100V 100p
7413 30p 74142 2001 741520 22p 9603 60p 4028 1149 0431400 704 NE566 155p *80182/3 14 4442955 100p 214698 45p '2145089 270 1144003/4 6p 84 400V 120p
7414 60p 74145 90p 741022 2Bp 4029 100p 043180E 100p NE587 1750 *8C184 Ilp MJ3001 225p 217064 20p '285172 27P 104005
INTERFACE 80 108 4001 200p
7418 27p 74147 194 741527 30p 4030 55p 00209 750p *NE571 425P BC187 30p *MJE340 65p 257084 20p 205179 27p 15400817 7p 25A 400V 400p
14
7417
7420
7421
27p 74148
17p 74150
40p 141514
154 741030
100p 741047
70p 741455
90p4033
22p

309
4401468 loop4031
MC1489 100
to: 4034
200p
180p
200p
1017106
111.8038
143014
925p
340p
34
RC4151
*S5780035
*00760135
41100
175P
144
*8C212/3
*8C214
80461
11 p
12p
350
MJE2955
MJE3055
*AAPF102
100p
70p
45p
20918
20930
201131/2
454
14
20p
285191
205194
*285245
83p
909
409
155901/3
185404/7 19p

7422 22p 74153 70p 141573 4035 110p 04311 190p '0876013ND 120p 80477/8 300 'WT103/4 409 281613 25p '285296 55p *ZENERS
75182
7423 319 74154 100p 741374 44 75450
230-
120'
4040 100p LM318 200p '011760238 14011 *80518/7 50p 141F105/6 40p 211711 25p *205401 50p 279-339 PLASTIC
.0576023ND 120p 400 mW Op 34 40 OV 60,
1425 30p 74155 94 141075 500 4041 801 LM324 70p *805476 14 *4414608 300 212102 800 *285451/8 40p
7426 404 74158 94 741583 1100
75451/2
15401,2
72
00p 4042 80p LM339 90p 'S5760335 175p *BC5490 184 *0400412 50p MIN 120p *285459 40p IW 10, 3A 5009
134 4000
85,
70p
7427 344 74157 70p 741585 100p '
' 4043 909 LM348 95p *008515 150P *805078 16p .MPSA56 324 2022194 ID4 *255460 400
7428 369 14159 1900 741586 40P C-MOS IC, 4044 90p *I.M377 174 *TU841E111 225p *8C559C lop *4001108 03p 2522224 20p '255485 44p 134 5006 1164

100p 741090 90p 74000 1300 *164380 99p 'T80800 90p 78p 252389A 15p '288027 44 84 400V 75p
7430 17p 74160 25p 4046 8CY70 lop '111PSU56 CRYSTALS
500V
7432 34 14161 100p 141093 90p 14002 24 4047 104 *1.8438145 150p '11101010 1000 0C171/2 22p 0028 130p 282484 309 258247 1900 10001H4 304 95p
7433 109 74162 100p 7415107 45P 74004 27p 4048 55p '043895 144 "TBA820 90p 80131/2 50p 005 1309 252848 50p 258254 130p I 55* 37p, 12BAA 400V 850
*TCA940 175p I2A 500V 105p
7437 34 74183 100p 7410112 1154 74008 27p 4049 40p 1M109 36p 81958 200p *020088 200p 282904/5 25p 208290 85P 32768 MH: 3500
7438 35, 74164 120p 7410123 759 7400 24 1050 49p 14710 54 *T041022 600P 81200 32p *1420101) 200p 20429084 21p 2016292 650 I6A 4000
16A 500V
110p
1440 17p 74165 100p 7410124 180p 74014 90p 4051 801 1M133 100p 082206 400p *13024413 35p '11129/1 40p 2129074 30p 38128 120p 1300
1441 74 74100 144 7410132 120p 74020 27p 4052 80P LM741 220 .082207 4000 '6F2560 70p '111290 55p '2142926 Op 38140 100P WIRE WRAP
71421 00p 74167 2009 7410133 600 74030 270 4053 80p LA1747 70p 402016 6750 6F251/41 32p 'TIP30A 48p 283053 20p 35201 1109 SOCKETS
0112240 400P 283054 65p 38204 100p THYR1STORS
1443 1120 74170 2404 1415138 60p 74032 36p 4055 125P LM748 354 131259 361 *11P30C 60p 14pin 40p
90p 253055 48p 40290 250p 460 14 501 40p
7444 112, 79172 720p 1415139 600 74042 1100 4056 135p 1M3900 70p '101414 "81039 300 TIP314 584 16 ,,,,,

7410151 1000 74048 4059 600p 1M3911 1300 214240 1350 283442 140p 40360 40P 24pin Hp IA 400V 65p
7445 100, 74173 120p 250p '00040 30p TIP31C 62p
7410153 60p 74073 75p 4080 115p LM4136 120p 25425E 400p 68p 2813553 240p 40361/2 45p 28pin 100p IA 600V 700
714116 113, 78174 93p *81041 300 71132A
1410157 BOp 1209 *MC13100 I50, 21410340 200p .253585 34 10361 120p 3A 400V 904
74474 709 74115 850 74174 70p 4083 *81079 30p 51320 B2p 40 pin 120p
90p 740158120p 74085 200p 4088 55p M01458 54 95590 BOOP '60080 51334 900 '283643/4 48p 40408 7Dp FIA 8009 140p
7448 80, 74116 10p
126 4000 1604
7450 17p 74177 90p 7410160 1300 74088 650 4068 22p
sn. VOIJAGEREGULATORS BFR81 30p TIP33C 114 '2043663 30p 40409 650
7410181 100p 74090 95p T11344 115p .2043702/3 12p 40410 65p I6A 100V 160p
7451 17p 74170 150p
40" "w FmedP*slicT0-220 BFX29 304 PLEASESENO
930 7415162 144 130p TIP34C 160p '2143704/5 12p 40411 300p 16A 400V 180p
7453 74180 74C95 344
17p
7415163 imp
"10
4071
34
22p
14 .F --ve
80830
225p '283706/7 120 40594 97p
SAE FOR FULL 164 6009 220,
7451 17, 74181 200p 740107 I25p 4,, 4,1, 60, 1605 fi. 130884/5 304 71135A LIST
'2N3108/9 104 9T108 110p
7480 171 74102 94 7410164 1200 140150 2504 4072 22p
I2V
'
1812 90p Va: BFX882/ 300 711350 294 12, 40595
7912 0108D 454
7470 34 741044 150p 740165 BOP 740151 264 4073 22, ..... -
1DV /BIS 90p 1915
i;Z: 61800 30p T1P384 270p 283773 308, 40603 58p
7472 30p 74105 150p 1410173 114 140157 254 4075 22p
181 7818 90p 7918 i;i: BFV410 94 TIP38C 3400 '283819 24 40673 75p .......,...... *M08101 36p
740174 114 140160 4078 107p 85, '283820 50, 40841 90p 4.."*. .4.4 213525 120p
7473 349 74186 700p I55p
90, 114"*. 80150 22, 71141A
1410175 114 408? 22p
24V 7824 7924
40871/2 90p
OURNEW *255060 349
7474 30p 74190 100P 140161 1550
7475 360 74191 1410181 320p 740162 155p 4062 22p
100mATO.92
84 ITORIES,00 ,, OTHER ADDRESS '255064 40p
7476 3511 74192 104 7410190 100P 74C103 I55p 4093 80p
59 78105 354
35p
79105
79112
"5-1013 ""
A15-2376 10004
3205 3200
7480 50p 74193 100p 7415191 100P 140164 120p 4098 107p
129 78112
...- - 1,16t 2102-2 125: 3245 404 LOW PROFILE 011 SOCKETS BY TEXAS
15v 28115 35p 78115 R113-2513 6000 4201
74111 104 74194 100p 1410192 144 140173 120p 4411 10500 --." 21078 500n 318,
8 sur 11p 10 pm 254 24 pin 33p
0111740262 1450p
049 74195 95p 1415193 1400 74C174 1600 4502 120p OTHER REGULATORS 2111-2 3250 4289 17011 i
24
'

28pm
74412
7483* 18, 14196 950 1410195 140P 740175 210p 4503 70p 1513098 1350 11146258 124 2112.2 300p
71406011 450 P 4801 600p I,
1 pin

pin
12p
139
20pin
12 pin 309 40 ten
420
51,
1484 108p 74197 804 1410196 1214 140192 1509 4507 55p 198317T 200p 11430 65P 2114 1500p EPROMS 6820 100,
74116 118p 74198 1500 1410221 104 740193 150p 4510 991 1A/13236 625p 78110561 174 5101 510p 1702A 5004 8850 704
7480 96, 74199 154 1410240240p 740194 220p 4511 154 151723 37p 711046720 136, 6810 400p 2708 0000 8205 324 VDU SYSTEM
7489 21110 74221 160p 7410241 244 140195 114 4514 250p OPTO-ELECTRONICS 2718 3000p 8212 225, As Natured in curven1 *sue. complete kit (49 mc VAT and
1410242 2451 174 4516 110p 255777 ROM/PROM, 4702 9009 8216 226p PAP liecludesalIpans is Wed).
74904 330 74251 140p 740221 45p 09012 90p ORP61 10p
7491 84 74259 250p 7415243 2459 4518 104 00071 134 08060 9014 11118 74
740188 225p 8224 188, 963840144142513U PCB 554
909 1416245300p 40000E111E0 4520 100p 0125' 110.02'
740287 4000 0,4 8228 576, 21021.011m0ovw 350,51160p
74928 469 74265
74930 33p 74278 290p 7410251 2000 4000 15p 4528 1000 11132 IR 75p T11220 Red 110
740387 400p 4040A 5700 8251 704
7494 849 74279 1409 1410257 120p 4001 I7p 4543 184 111.209 Red 13p 711222Gr 11p
93427 400p 6602 imp 8255 554 VAT RATES - All items at 8% except
7496A 74 74283 190p 7410259 175p 4002 17p 4553 454 711211 Gr 20p TIL228 Red 22p 93436 6609 6000 900p 9905 2000 ;narked which are at 12;16
7496 65p 74284 400, 7410298 249p 4006 95p 4560 2501 T112120, 25p M954917S 1209 93446 6500 80804 600p 9908 276,
7497 180p 74285 4004 7445373200v 4007 14 4583 90p 1112160W 18p Clips 3p
74100 130p 74290 1500 7410374 195p 4008 800 4504 90p Please Add 250 189 & VAT
124
TECHNOMATIC LTD
DISPLAYS FN0357
74104 65p 14293 1500 811095 160 p 4009 40p 40014 900
4010 60p 40085 3015F 200p 0110500 120p Cott. Colleges. etc. Orders accepted
74105 74294 200p 811096 160p 200p
65p
34 74298 200p 811097 16Dp 4011 17p 40097 900
01704 140 001507120
74107
74109
14110
550
Sop
14385
74366
1500 814590
144 8128
160p
230p
4012
4013
14 14433 [II
600 SHIFT REG
01707
707 Gr
Fled 140:
1400
711311
111317/)
600"
110'
9"11'''
Welcome
9""" Pri 9 39 539
Saturday 1030-430 I 17 BURNLEY ROAD, LONDON NWI 0
14111 70p 14361 1500 9301 160p 4014 540 4.842833 400p 01741 Red
747 Gr
225p
225p
011321/2
711330
130"
140: 2 mins DOLLIS HILL Tube Ample Car Perking Tel: 01-452 1500 Telex: 922800

INDEX TO ADVERTISERS
Ace Mailtronix Ltd 1106 Fotherby, Willis Electronics Ltd 1034 Progressive Radio 1119
Adam Hall (P.E. Supplies) 1118 Proops Bros. Ltd 1092
Alben Engineering 1040 G.C.H.Q 1117 Proto Design 1117
Alcon Instruments Ltd 1086, 1110 Gemini Electronics 1096
Astra-pak 1034 George, Brian Engineering 1104 Radio Component Specialists 1113
Aura sounds 1043 Goddards Components 1112 Ramar Constructor Service 1117
Greenweld Electronics 1114 R.S.T. Valve Mail Order 1110
B.I.E.T. 1047 Radio & T.V. Components 1085
Barrie Electronics 1119 Harversons 1108
Bi-Pak 1044, 1045 Heathkit Ltd 1036 1116
Sandwell Plant
Birkett J. 1106 Home Radio 1110 Saxon Entertainments 1038, 1039
Boffin Projects 1118 Scientific Wire Co 1118
British National Radio & Electronics I.C.S. Intertext 1106, 1117
1107 Sentinel Supply 1039
School 1042, 1103 I.L.P. Electronics
Service Trading cover iii
J.W.B. Radio 1116 Sinclair Radionics Ltd 1091
Cambridge Kits 1117 Sintel Ltd 1117
Cambridge Learning 1109 1108 Special Products Distributors Ltd 1036
K. & A. Distributors
Canon Components 1104 Squire, Roger 1108
Chromasonic 1114 Lion House 1111 Sugden A.R. & Co 1092
Clef Products 1108 Swanley Electronics 1104
Codespeed 1116 Mantec Ltd 1119
Component Centre, The 1086 Maplin Electronic Supplies cover iv
Technomatic Ltd 1120
Continental Specialties 1095 Marshall A. (London) Ltd 1115
1117 Teleplay (Logic Leisure) cover ii
Crescent Radio Ltd 1114 M H EL Electronics
Tempus 1096
Crimson Electrik 1048 Micron R/C 1118
T.K. Electronics 1039
Crofton Electronics 1117 Mill Hill Supplies 1040
1118 Trampus Electronics 1042
C.R. Supply Co 1116 Minikits Electronics
1104 Trent Electronics 1118
CVVAS Alarm 1118 Modern Book Co
T.U.A.0 1105
Moulded Electronics Components Int. Ltd 1112
Davian Electronics 1042
Doram Electronics 1086, 1112 O.K. Machine & Took (UK) Ltd 1048 Vero Electronics 1036
Odik Electronics 1118 Videotime Products 1118
E.D.A 1040
Eagle International 1035 P.K.G. Electronics 1117 Watford Electronics 1037
Electrovalue Ctd 1041 Personal Safety 1118 Williams, Michael Electronics 1034
Phonosonics 1046, 1047 Williamson Amplification 1117
Flairline Supplies 1096 Powell T. 1092 Wilmslow Audio 1048

Published approximately on the 15th of each month by IPC Magazines Ltd.. Westover House, west Quay Road, Poole, Dorset BH15 11G. Printed in England by Chapel River Press, Andover. rants.
Sole Agents for Australia and New Zealand -Gordon & Gotch (A/sia) Ltd.: South Africa -Central News Agency Ltd.
Subscnptions INLAND and OVERSEAS £10.60 payable to IPC Services, Oakfield House, Perrymount Road, Haywards Heath, Sussex.
Practical Electronics is sold subject to the following conditions, namely, that it shall not, without the written consent of the Publishers first given, be lent, resold, hired out or otherwise disposed of by way of
Trade at more than the recommended selling price shown on the cover, excluding Eire where the selling price is subject to V.A.T., and that it shall not be lent, resold or hired out or otherwise disposed of in a
mutilated condition or in any unauthorised cover byway of Trade, or affixed to or as part of any publication or advertising, literary or pictorial matter whatsoever.
 etc.
RELAYS MINIATUREP LRELAYS VARIABLE VOLTAGE TRANSFORMERS GEARED MOTORS
100 p.. 1151b.l. 110V 50Hz 2 BA.
single phase split capacitor motor
RELAYS. WIDE RANGE OF A.C. end D.C. RELAYS Immense power Continuously rated
AVAILABLE from stock, phone or write in your enquiries INPUT 230/240V a.c. 50/60 OUTPUT Totany enclosed Fan cooled in -line
VARIABLE 0-260V All Types _.
gearbox Length 250mm Dia 135rhrn Spindle dia 15 5rnm
FT3 NEON FLASH TUBE SHROUDED TYPE ' ' Length 145mm Ex -equipment tested 612. Post El 501(14/56
200 watt 11 amp) inc a.c. voltmeter ,.............;
,t_C 3
inc VAT & P j Suitable transformer 230 240V operation Et.
High intensity multi turn. high voltage. neon 0.5 KVA 121 amp/ (MAX) Post 75p (69 45 inc. VAT 6 P
glow. discharge flash tube Design for ignition £17.00
1 KVA (5 amp) (MAX) £22.50
timing, etc £1-50. P 8P 25p 1t1 .89 inc VAT) 3
for E3. P & P 50p t(3.76 Inc VAT 8 P ) 2 KVA 110 amp)1MAX)
3 KVA 115 amp) (MAX)
£37/130 GEARED MOTORS N.M.S.
E45.50
5 KVA 125 amp) (MAXI £74.00 yi
28 r.p.m. 20 lbs inch
-,F.Af'
NI -CAD BATTERY Height
ImMI
Width
Imml
Length
Imm)
10 KVA (50 amp/ (MAX/
15 KVA (75 amp) (MAX)
£168.00
C260.00
- 1 15v a.c. Reversible 'noise.
71 r.p.m. 1011ss inch
115v. a.c Reversible motor.
,

,7-_,
35AH 1 2V Metal 67-56 219 75 29 CARRIAGE AND PACKING EXTRA
Post 50p per unit Both types similar to above drawing. Price either type £4.75
LT TRANSFORMERS p&p 75p. (15 94 inc VAT p&pl
Supplied complete with transformer for 240v a.c. operation
WHY PAY MORE? 0-10-15V at 3 amp lex new equip) £250 P. & P 50p 10/24 £725 p&p El /001E8-91 inc VAT p&p)
MULTI RANGE METER Type MF15A a.c. d.c. -- inc. VAT)
volts 10 - 50. 250. 500. 1000. Ma 0-5, 0-10. 13-0. 13V at 1 amp £2.50 P. & P. 50p1£3/24 inc VATI Crouzet 230/240V AC 2RPM synchronous geared motor.
0-100. Sensitivity 2000V. 24 range, diameter 25-0-25V at 21 amp £4.50 P. & P. 75p (C5.67 Inc VAT & P.I Brand new £2,90 p&p 30p (f3 45 nil VATI (quantity discount
133 by 93 by 46mm including test leads. Pp,.,' 0-4V/6V/24V/32V at 12 amp £1500 P. & P 11.501E17/82 inc available.)
£7.00 plus 50p P. & P. (f8.10 inc. VAT & P.) P
VAT & P.)
0-6V/12V at 20 amp E13.50 P. & P 11 50 (inc VAT £16-201 FRACMO GEARED MOTOR tu.1,
0-12V at 20 amp or 0.-24V at 10 amp £12.00 P. & P fl 50 56 r.p.m.. 50Ib.in. 240V a c. 50Hz. 0 7
METERS (New) - 90 rnm DIAMETER (C14.58 inc VAT & P.) amp sharplength 35mrn, Ma 16mm. .._,

A.C. Amp.. Type 62T2.0 -1A, 0-5A., 0 -15A.,0 -20A. 0-6V/12V at 10 amp £13/25 P. & P E 125 line VAT £10261 weight 6 kilos 600 grammes Price £1500
A.C. Volt. 0-15V.. 0-300V. p 8P El 501E17821
0-6V/12V/17Vi 1 8V/20V al 20 amp £16.50 P & P Cl 50 N.M.S
D.C. Amp., Type 65C5. 0-2A., 0-10A.. 0-20A., 0-100A, ((1944 inc VAT & P.)
D.C. Volt. 0-15V., 0-30V, 0- 10Vi1 7V. 18V at 10 amp £10.00 P. & P. 61.40 (inc VAT
All types £3.50 ea. a P. & P. 50p (£4.32 inc) VAT). except
0-100A. D.C.. price £5.00 + 50p. P. & P. (£5.94 incl. VATI. £1231)
Other types in stock: phone for enquiries or send sac for leaflet.
PARVALUX GEARED MOTOR
NEW HEAVY DUTY SOLENOID. mfg. STROBE! STROBE! STROBE! 230/240V A.C.30 rpm 50Ibs inch Price
by Magnetic Devices, 240V a.c. opera- ...1.11MBIN, 1 C15.00 P & P 11 00 1£17.82 inc. VAT)
tion approx. 10Ibs pull at 1.25in. Price A.; r, .
-__ -'
£4.00 P & P. 60p. (04.96 inc. VAT & comeNVIINIOW) HY-LIGHT STROBE KIT MK IV N.M.S
P.). Similar in appearance to illustra-
tion. Approx. 14 Ib pull. Sin of feet 11 a
t., _ip Latest type Xenon white light flash tube. Solid state
Bin. Price £1.00 P. & P. 25p. timing and triggering circuit 230/240V a.c. operation.
Designed for larger rooms, halls. etc. Speed adjustable
EXLT. 1-20 1.p.s. Light output greater than many Iso called 4 PARVALUX 230/250V a.c. MOTOR
! Joule) strobes. Price £19.00. Post El IC21.60 incl. VAT 500 rpm, 3;lbs inch. 2 right angled spindles £11.00 P -.
& P.1. Specially designed case and reflector for Hy -Light I 1.00 (£12:96 inc. VAT & P./.
£8.80. Post 1 1 1E10.58 inc. VAT & P.1.
MINIATURE mAt" N.M.S.

UNISELECTOR
-781'
12 volt 11 -way, 4 bank 13 non -
XENON FLASHGUN CITENCO 19 RPM
bridging, 1 homing), £2.50
P. & P. 35p IC3.08 inc. VAT & Pi. 11/4.*Slile,
TUBES
Range available from stock
A.71)",-.----
___ _
FHP motor type C 7333,15 22C 240V a
rpm reversible motor torque 14 r
gear ratio 144-1 Brand new -
.
.v
ilitlif
-M1091-1'
6

S A F to. details capacitors our price £1125. P 8 P I ' (I.

600 WATT DIMMER SWITCH /E16 / 20 inc VAT & P I
N.M S
Easily f /tied Fully guaranteed by makers Will
control up to 600W of lighting except fluorescent WIDE RANGE OF DISCO LIGHTING
,A.,...... al mains v011age Complete with simple
EQUIPMENT
kilij L3.95. post 25p 164. 53 me VAT 8 P 1
1.000 watt model C560, post 25p 1t6 32 inc VAT SAE ifoolscapi for details PROGRAMME TIMERS
8 P t 2 000 watt model E9.75. post 40p 1(10 96 '` ...
inc VAT 8 P I Superior Quality Precision Made -
In
operd pi
'.' 17.', 5so0. aPyoaoilrab6le°Pfolr.(850?`5. 1:.. o-ei o.1 et-ofii,11,114,,'
Pr , e ci, dbOve
MICRO SWITCHES NEW POWER RHEOSTATS N.M.S.
Sub min Honeywell roller m/s type 3115m 906t. New ceramic construction, vitreous
10 for 02.50 post paid.
LEVER OPERATED 20 amp. C/0. Mfg. by Unimax
USA 10 for C4,P. & P. 50p (mm. order 101
25 WATT 10/25/50/100/150/250/500/11,D/
enamel embedded winding heavy duty
brush assembly, continuously rated, / Time Switch
Venner Type ERD Time switc, 200.250V d u
i C4.86 inc. VATI.
D P C0 lever m/switch mfg. by Cherry Co. USA. Precious metal 1 -5k0, C240. Post 20p If281 inc. VAT & P./. 30 amp contact 2 on/2 off every 24 hrs. at any
rn.s resisIdnce contacts. 10 for £2.25 P. & P. 30p. Total inc. VAT 50 WATT 100/2500 E2.90. Post 25p (C3.40 inc. VAT & P.). manually pre-set time. 36 hour Spring Reserve
E302 (min 101. 100 WATT 1/5/10/25/50/100/250/500/1 k0/1-5k0/2.5k0 and day omitting device. Built to highest Elec-
tricity BOard specification. Price £7 75.
;ill. min Inver in ,..,itch type MME. 4fi 10 for £2 50. N.M.S./3.5k0 £5/90 p & p 35p 1E6.75 inc VATI.u P & P 75p If9.181.
Bleck, Silver, Skirted knob calibrated in Nos. 1-9 11in. '-i --i
dia. brass bush. Ideal for above Rheostats 24p each. R&T
24 VOLT DC SOLENOIDS
UNIT rig I
neavy Cluny sole, 2510 pun dpprov RESET COUNTER SANGAMO WESTON TIME SWITCH
rich -,..- 'wo approx 1 ib psi
-
navel 6 appro.
.
'
1

230V a.c.. 3 digits mfg. Veeder Root Type Type 5251 200/250V, ac. 2 on,2 off every 24 hours 20
40,7 p .
awsi One 24V is c i ',dr, duly single make LL 1441 £1.75. P. & P. 25p 1£2.16 inc. VAT & amps contacts with override switch die 4 x 3 price £6.50 r & P
relay I' - £3 Post £1 (64 32 inc VAT & P P.I. 7 Fg 24V d.c. non set £1.50. P. & P. 25p 50p inc VAT £7.58. Also available with Solar dial.
BARGAIN
I
ABSOLUTE
(049 inc. VAT & PI. 6 fig. 24V d.c. resettable R. & T
-
£3. P. & P. 25p (£351 mc VAT & P I
VORTEX BLOWER AND VACUUM UNIT N.M.S. FRACMO MOTOR
1400 rpm H.P. 1/30 continuously rated 115V a.c.. supplied
Dynamically balanced totally en- imiii, complete with transformer for 230/240V a c. op. Complete with
closed gin rotor with max air
delivery of 5 cubic metres per
230V a.c. FAN ASSEMBLY. anti vibration cradle mounting £10-00 P. & P E 1 .00 IC11.88
1

min Max static pressure 600mm ' Powerful continuously rated a c motor inc. VAT & P.1
W G Suction or blow from 2 side- ! complete with 5 blade 61 -in. Aluminium
N.M.S.

lay -side 37mm i D circutar aper- fan. Price £3.00. P. & P. 65p IC3-94). N.M.S.
tures toted to base of unit Power-
ROTARY VACUUM
ful or rated 115V a C ULTRA VIOLET BLACK LIGHT AIR COMPRESSOR
motor mounted on alloy base with FLUORESCENT TUBES .
fixing
iength 'Wm
facilities Dimensions 1 MI. 40 yr.. 157.75 (C.OrS OA. 2.1.. SO MM. ti.kt. PON 6. & PUMP '
width 25cm wwv.vmsw. ,{. use In sim P../N.4n., Min, 125111.001.51.150,05. no
Carbon vane oil tree vacuum pump `1.,
height 25cny These units are ex equipment but have had ([Linn vAr PI 9. 5wsn C2.00 Pew 25p (C2.4.30.5 vAr ,

& Pi 6. 4 watt t 1.75 Post 25p1152.211,nc 5042 Pi and compressor. Approx. 20 inch I
minimum use Fully tested prior to despatch Price [12 Compive wont wet Ell'. (r 9- our?" muss 230V A C AA vacuum. 10 PSI at 79 CFM
I 1 50 P 8 P (14 58 inc VAT 8 P I 4 a .so Pus PG. 40p 154.21 ,Ilf viii &et Aka avAtoble for 125
D C op 13.51 Plus NIP Pon ,54.21,M DAT 515
Powered by 110V a 1.8 amp
Suitable Tr,,' ',er for 230 240V a c (6 El P 8 P 167 56 - Parvalux motor fitted with additional shaft at rear suitable
.tit XF
vA 1/ light loads. Inc capacitor E7400 p&p E1 50 1E16/74 inc VAT
SQUAD LIGHT ..",,,
N.
.',-, isp&pp4SltnlaZii,t;arnrm\e/rATfo:pi300/240V a.c operation
00

--
CENTRIFUGAL BLOWER A new conception in light ___ _ N.M.S
control. Four channels each , '..C......'
Smith type FFB capable of handling..750 watts ' - -' Yet another outstanding offer.
1906 022 220/240V A.G. Aperture of spotlights, floodlights or dozens of small mains lamps. Seven
10 x 44cm overall size 16 x 14crn. Price programs all speed controlled plus flash modulation effectively
giving 14 different displays. Makes sound -to -light obsolete.
New IMFD 600V Dubilier wire ended capacitors
£3.75 'P & P. 75p. (inc. VAT f41161. 10 for £1,50 p&p 50p. 112 16 inc VAT p&pl Min 101
Other tv iv, dvailahle on request Completely electrically and mechanically noise free.
NMs Price only £6000
Post 75p S.A.E. (Foolscap/ for further details. RELAY N M.S
INSULATION TESTERS NEW! Diamond H heavy duty A.C. relay 230/240V a.c.
on s e tor. bench or - .i.
VAT two C/0 contacts 25 amps res at 250 a.c. £230
p&p 50p. 113.24 inc VAT .- p&p) Special base 50p.
AT CURRENT RATE MUST BE
.-,

onsra," coed..c clutch Site 1.n - .,,, .1, n 1451

H bin weight 61b, 500V. 500 Megoluns £49.
Post 80p (653-78 inc. VAT & P.). 1.000V ADDED TO ALL ORDERS FOR THE KEY
1,000M D, £55. Post 80p (£60.26 inc VAT &
P SAE for leaflet TOTAL VALUE OF GOODS N.M S New Manufacturers Surplus
INCLUDING POSTAGE UNLESS R. & T.
Ex L.T.
Reconditioned and Tested
Ex London Transport
All Mail Orders -Callers ---Ample Parking OTHERWISE STATED

SERVICE
..
Personal callers only Open Saturdays
Dept. PE, 57 BRIDGMAN ROAD
CHISWICK, LONDON W4 5BB 9 LITTLE NEWPORT STREET
Phone 01-995 1560
Showroom open Mon. -Fri
TRADING CO.
ACCOUNT CUSTOMERS MIN. ORDER £10.00
LONDON WC2H 7JJ
Phone 01-437 0576
 maxi
everything for the modern D.IY electronics enthusiast and more.

10 CHANNEL STEREO
GRAPHIC EQUALISER
A new design with no difficult coils to
100W RMS STEREO DISCO
wind, but a specification that puts it in the INTEGRATED
top-flight hi-fi class. All this for around
A genuine MS per channel (both channels £70 including fully punched and printed CIRCUITS
Invenl stereo with auto fade on microph, VU metalwork and woodwork. Send for our
"eters. full Over 35 pages in our catalogue devoted
monitoring and component schedule now. to hundreds of useful I.C.s. All with
..sing facilities Full construction details data, pin connections and many with
ind a very high price 25p. (All prices
ituality light applications circuits and projects to
show. Complete include V.A.T. and p & p) build. Post the coupon nowt
construction
booklet MES41,
price 25p. Cabinet
comes complete
with lid and
carrying handles.
VERY 0

LOW -DISTORTION
AUDIO OSCILLATOR TOUCH -SENSITIVE
The very low distortion sine wave 1...0.0190 outi,
suitable for testing very high quality hi-fi audio
equipment. Also
PIANO
square wave output. Range The revolutionary new IC AY -1-1320 first
20Hz to 26kHz. Output OV
to 1V in three continuously seen on 'Tomorrow's World' is now
variable steps. Total cost available. Complete kit of IC's to build a
around £21. Full 60 -note piano (18 x 1C's) order as HQ53H
construction details in our
catalogue. Send the price £36.86. Preliminary circuit details in
coupon below, now our October newsletter. Complete design,
(All prices include V.A.T
and p & pl pcb's attractive veneered wooden cabinet
available soon. It's the
most realistic -sounding SWITCHES
PEDAL UNIT electronic piano we've
We stock a wide range of switches
ever heard and includes
A completely self-contained pedal unit. including a really low-priced high
simulated damping, loud
13 -note. 2 -Octave range. 4 organ stops. quality interlocking push-button
and soft pedals. Full
It can be added to any organ. A really switch system which is
details in our newsletters.
extremely versatile. We've got
unusual extra is the bass guitar stop (All prices include V.A.T.
toggle switches, slide switches,
which uses four envelope shapers to give and p & p1
push switches, rotary switches -
a real bass guitar sound. A must for the there are dozens to choose from,
solo guitarist. Full construction details in but it's only a tiny part of our
our catalogue - post the coupon below, fantastic range.
now!

SYNTHESISER
The International 4600 Synthesiser. A
very comprehensive unit. Over 400 sold.
We stock all the parts costing less than
£500 including fully punched and
printed metalwork and a smart teak
cabinet. Far less than half what you'd
pay for a ready made synthesiser of
equal quality. Specification on request.
'PE' STRING Full construction details in our
ENSEMBLE construction book £1.50. (All prices
Unbeatable prices and finest quality include V.A.T. and p & p) OulAufly newsletter you up to date with latest
components only when you buy from guaranteed prices -aur latest special
projects and new hoes. Send 30p
Maplin. All parts available to build this for nest discount voucher with each.3W
fascinating project. Component schedule
available shortly (s.a.e. appreciated). Av.
1.11, 01(
Demonstration model in our shop soon.
Phone now and compare our prices. Estatics,.//...,
* POST THIS COUPON NOW FOR YOUR COPY OF OUR
* Look inside for our ** 1977 CATALOGUE PRICE 60p
:4 page special pull out*, Please rush me a copy of your 216 page catalogue
* featuring the New * I enclose 60p, but understand that if I am not comple:,,,
**79-80 catalogue*** satisfied I may return the catalogue to you within
14 days and have my 60p refunded immediately.
***** ***
NAME
MAPLIN ELECTRONIC SUPPLIES
P.O. BOX 3 RAYLEIGH ESSEX SS6 8LR ADDRESS_
Telephone: Southend (0702) 71515 5
Shop. 284, London Road. Westcllff-on-Sea. Essex
(Closed on Monday( Telephone Southend it
PE (0