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1/ BUILD AN 2/ READ, DRAW

OSCILLOSCOPE AND UNDERSTAND
CIRCUIT DIAGRAMS
You learn how to build
an oscilloscope which
remains your property.
With it, you will become
familiar with all the
components used in as used currently in the
RAPY electronics. various fields of electronics.

3/ CARRY OUT valve experiments, transistor experiments

This new style course will enable anyone to
really understand electronics by a modern,
amplifiers, oscillators, signal tracer, pho-
OVER practical and visual method-no maths, and
40 EXPERIMENTS
to electric circuit, computer circuit, basic
radio receiver, electronic switch, simple
a minimum of theory-no previous knowledge
required. It will also enable anyone to under-
ON BASIC ELECTRONIC transmitter, a.c. experiments, d.c. experi-
stand how to test, service and maintain all
ments, simple counter, time delay circuit,
CIRCUITS & SEE HOW servicing procedures.
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PRACTICAL VOL. 49 NO. 3

ISSUE 797

WIRELESS JULY 1973

BRITAIN'S PREMIER MAGAZINE FOR THE DO-IT-YOURSELF RADIO AND ELECTRONICS CONSTRUCTOR

EDITOR NEWS & COMMENT

Morris A. Colwell
216 FORMATIVE HABITS-Leader article and August preview
ASSISTANT EDITOR 217 NEWS ... NEWS ... NEWS
Lionel E. Howes, G3AYA
229 TELEVISION-This month's attractions
ART EDITOR 230 PRODUCTION LINES-Products reviewed by Colin Riches
Peter Metalli
234 PRACTICALLY WIRELESS-Light hearted view by Henry
TECHNICAL EDITOR 239 NEXT MONTH in Practical Wireless
Eric Dowdeswell, G4AR
254 ON THE AIR-Reports on Broadcast Bands
PRODUCTION & NEWS 254 Short Wave-Malcolm Connah
EDITOR Colin R. Riches 257 Medium Wave-Charles Molloy
SECRETARIAL 257 V.H.F./F.M.-Simon David
Jenny Maunder 258 Amateur Bands, Short Wave/V.H.F.-David Gibson G3JDG
Jill Alflatt
Telephone 01-634 4292 261 DEAR SIR-Readers' letters to the Editor
262 HOTLINES on recent developments-Ginsberg
ADVT. MANAGER
Roy Smith
Telephone 01-634 4293
CONSTRUCTIONAL
CLASSIFIED ADVTS. 218 EXTRA BANDS F.M. RECEIVER-F. G. Rayer
ColinR. Brown
Telephone 01-634 4301 235 I.C. PROCESS TIMER (0-99 seconds)-G. H. Woods
240 TREMOLO GENERATOR for guitars and organs-R. Morgan
246 3 -BAND TRANSMITTER, Part 2-V.F.O.-F. G. Rayer G3OGR
SUBSCRIPTIONS
Subscription Rates for one year to any 260 TAKE 20 No. 50 Electronic Siren-David Andrews
part of the world 82.65 including
postage. Enquiries to Subscription 265 "P.W. TRICOLOUR" Mood Lighting System, Part 4-J. Budek
Department, IPC Magazines Ltd.,
Carlton House, 68 Gt. Queen Street,
London, WC2 5DD. Phone 01-242 4477
Binders (51 10) and Indexes (11p) can
be supplied by the Binders Dept at the
OTHER FEATURES
same address. 225 MAGNETIC AMPLIFIERS, Part 1-/. R. Sinclair
233 I.C. OF THE MONTH, TBA435 Voltage Regulator-
L. A. J. Ireland
BACK NUMBERS
We regret that we are unable to supply 250 GOING BACK Equipment of yesteryear-
back numbers of Practical Wireless.
Readers are recommended to enquire Colin Riches and Arthur Dow
at a public library to see copies. Re-
quests for specific back numbers of
Practical Wireless and Television only Published by IPC Magazines Ltd., Fleetway House, Farringdon Street, London
can be published in our CO Column. EC4A 4AD. Telephone: 01-634 4444.

COPYRIGHT AND QUERIES

© IPC Magazines Limited 1973. Copyright in all drawings, photographs and articles published in "Practical Wireless" is fully protected and
reproduction or imitation in whole or in part is expressly forbidden. All reasonable precautions are taken by "Practical Wireless" 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 are those current as we go to press.
We regret that we cannot answer technical queries by telephone nor can we provide Information or advice on manufacturers' products other
than that given in the magazine. We will endeavour to assist readers who have queries relating to articles published but we cannot offer
advice on modifications to our published designs. All correspondents expecting a reply should enclose a stamped addressed envelope.
193
 PACKAGE PR:3E R.S.C. STEREO PACKAGE OFFERS HIGH FIDELITY UNITS
FOR ILLUSTRATED UNITS R.S.C. ASS
LOUDSPEAKERS
SAVE £29.89 IP= GE£108.251.r%
ONLY FOR ILLUSTRATED
MONARCH UNITS
£39.99 SPEAKERS
12
Or deposit 61600 and
monthly payments 18.78
Carr. 1130 (Total á3604e)
Or deposit l69á GOL1RRIING
and 9 monthly t:OLDEING GL72 Trans-
payment. 64ßY cription Turntable + P.1
(Total 14498M. t ;OLDRING 0800
GARRARD 2025 Magnetic Cartridge
OE -LUXE PLINTH
LINEAR 505 AMP with Roll-over Cover
Pair R.B.C. MONARCH
Individual Bec. Retail friers LOUDSPEAKERS
LINEAR 005 5 + 3 Watt Amplifier .. .. . £1925 SEND S.A.E. FOR R.S.C. SUPER 30
GARRARD 2026 Autochanger + K840A Cartridge .. 61244 Mk III AMPLIFIER
Teak Veneer Plinth with Transparent Plastic Cover 1690 FREE COLOUR
Pair A55 LOUDSPEAKERS (Inc 8" x 5" 10,000 (Muse) 51986 'SUPER 30' AMP Total value o! individual item.
TOTAL BROCHURE listed above 613814.
14941

FANE ' MODE ONE' HIGH FIDELITY SPEAKER KIT SPIOI HIGH FIDELITY PLAYER UNIT
Incorporating a model 803 8" 13,000 Gauss Bass Speaker Comprising Goldring G101 hi-fi single player unit fitted high fidelity
svith ultra low resonance. P.V.C. surround cone. free field magnetic stereo cartridge with diamond stylus. Belt driven
Printed circuit cross-over assembly with ferrite Attractive design super -slim plinth and 'roll-over' transparent tinted
cored coils. Model 303 Pressure Tweeter, Acoustic
damping material, Screws, Panels etc., and in- plastic cover. Excellent value. Or Deposit £4.95 and £34.95
Post
structive diagrams, Frequency £9,06 post 9 Monthly Payments of £3.75 (Total £38.70) paid
Response 25 Hz -20 kHz. free
Impedance 8-15 nhmc. Or Dep. £2 A 9 u,thly
Promss Cl 07 fil
iT..i a3i HIGH FIDELITY LOUDSPEAKER UNITS
Cabinets latest style Satin Teak veneer. Acoustically lined or filled
RSC G66 Mk II 6.6 WATT high quality STEREO AMPLIFIER acoustic damping. Ported where appropriate. Credit terms available.
DORCHESTER (Illustrated) Size 16x 11 x 9in. app/r.. Range 45-15,000
Individual Ganged Controls: Bass, Treble, Volume and Balance. Printed 58
circuit construction employing 10 Transistors plus Diodes. Output
c.Dual
7.45
ng 8-10 watts. Fitted High flux 13 x Bln.
rating I.H.F.M. Frequency range 20-20,000c.p.s. Bass Control
Treble Control t 12db.
I3db. Selector switch for
t Cone speaker. Carr. 40p.
MONARCH Size 19X104X9in. approx. Rating 10 watts. Inc. 13 x81n. speake, ,i
highly flexible P.V.C. cone surround, long throw voice coil and 10,000 line magnet.
P.U. or Tape/Radio. For loudspeaker out- High flux pressure tweeter. Handsome design eabinet. Range 36.20,000 c.p.a Imp.
8 ohms. Hive. smooth realistic Bound output.
put impedances of 3 to 15 ohms. For See 'package offers' !or lllostratioa. Carr. á0p E 19,35
standard 200-250v. A.C. mains operation.
Attractive Black and Silver finished metal
fascia plate and matching control knobs. HI-FI SPEAKER ENCLOSURES MODERN DESIGN
COMPLETE BIT OF PARTS INCLUDING Teak veneer finish. Acoustically lined. Size. approx. Carr. 34. per em
FULLY WIRED PRINTED CIRCUIT and JE8 Size 16" x 11" x 9". SE8 For optimum perform-
CoMPEKHEIVE DIAGRAMS
265
IN
Or FACTORY B BUILT IN TEAK VENEERED CABINET
u
E . 0p` Pressurised. Gives pleasing ance with any 8in.
results with any Hi-Fi spkr. £6'50
illustrated 816.50 or dep. 88 and 9 monthly payments gl88 (Total 818.9/).
8in. Hi-Fi speaker. £5.50
Size 19 x 101 x 9in.
AUDIOTRINE HIGH FIDELITY SPEAKERS SE12 For excellent
Heavy construction. Latest high efficiency ceramic magnet.. SE10 For outstanding results performance with 12in.
Plasticised Cone surround. "D" indicate. Tweeter Cone providing with IOin. Hi-Fi Hi-Fi speaker and tweeter
extended frequency range up to 16,000 c.p.e. Impedance 3 or
845 ohms. PLEASE STATE CHOICE. .
spkr. Size 25# r 16
x 9in. P'td.
£6.75
Size
25# x 16 x 9in. £7.95
Exceptional performance al low cost.
111,808T 8- 10W 1298 1111120D 18- 16W 15.60
HP102D 10- 10W 88.10 HF126 11" 16W 18.86 AUDIOTRINE HI-FI SPEAKER SYSTEMS
HF120 12' 15W 04.95 HP118D 12 15W gee Consisting of matched 12in. 11,000 line 15 Watt 15 ohm
high quality speaker, cross-over unit and tweeter. Smooth
FANE 8071 HIGH FIDELITY SPEAKER response and extended frequency range £6
.A full range 8in. 10 watt unit for excellent sound quality in suitable ensure surprisingly realistic reproduction. 50 Carr.
33p
enclosure. Cast chamois Roll P.V.C. cone surround and long throw voice OR SENIOR 15 WAIT ING £7.65 9pr.
coil to achieve very low fundamental resonance of 80 c.p.a. Tweeter HF126 15,000 LINE SPEAKER
cone is fitted to extend high note response. Frequency range 29 Hs to
16 KHz. Gaues 10,000. Impedance 3 or 8-16 0.
E3.70
PLEASE STATE IMPEDANCE WHEN ORDERING
MODEL 808T 8" 15w, with parasitic Tweeter. R.S.C. TA6 6 Watt HI-FI AMPLIFIER
Respon.c 25 Hz to 15 KHz. Gauss 13,000 Imp 3 or £4.95 200-860v. AC mains operated. Frequency Reepon.e 30-20.000
-2dB. Harmonic Di.tortioa 0-3% at 1,000 c.p.a. Separate Baas ami
R.S.C. BATTERY/MAINS CONVERSION UNITS Treble 'litt and cut' control.. 3 input sockets for Mike. Gram, Radio
or Tape. Input selector switch. Output for 3-16 ohm epkro. Max. ce0.01i, its 5u,1'
TYPE Mil. Au all -dry battery eliminator. Bins 64 x 44 x 21n. Output rating I.H.F.M. Fully eoclwed enamelled case. 91 X21 x51in. Attractive
approx. Completely replaces batteries euDplying 1áv and 00v, brushed silver finish facia plate 104x 31ín. and uutehing knobs.
to battery radio where A.C. mains 200/250v. Complete kit o1 parts with full wiring diagrams and inatructiou.
10v/s Is available. ASSEMBLED READY FOR USE E8.50 (Sere.
40p.
E4.15 OR FACTORY BUILT WITH 12 MONTHS' GUARANTEE E1205
GUARANTEED. Impregnated and Interleaved where necessary. BBLEBIUW
R.S.C. TRANSFORMERS, L.F. CHOKES & RECTIFIERS FULLY Primarias 200.650v. 603/s. Screened RECTIFIERS
MIDGET CLAMPED TYPE 21 x 31 x slit. CHARGER TRANSFORMERS 0.9.15v. 112..11.10. F. W. (Bridged)
TOP SHROUDED DROP-THRO' TYPE
250v., 60mA, 63v. sa 11.10 260-0.250v. 70mA, 6.3v. 2a.. 0.5.6 3v. 2a. 61.49 24s. 6126; Sall -40; Sa.11.60; 6x.11.86: 0a-12.20 All 6/12v. D.C.
250.0.250v., 60,nA 63v 3a 11.18 260-0.2150v. 100mA, 63v. 3-áa. 61.71 AUTO (Step UP/step DOWN) TRANSFORMERS output. Max. A.C.
250.0.250e. 100mA, 0.3v. 2a., 6.Sv. la. 61.76 0-110/120v. 200-230-250e. 60-80 watte 1126. input 18v.
FULLY SHROUDED UPRIGHT MOUNTING 860.0-350v. 80mA, 63v. 2a., 0-5-6.3v. 2a. 61.81 160 watt., 12-10 250 watts U-00; 500 watts 06.40 la, 88. 2a, 89p.
250.0.230v. 100mA, 6.3o. 4a., 0 -5-6 -Sv. fia. 12.46 OUTPUT TRANSFORMERS Sa, 55p. le. 72p.
250.0-250v. 60mA, 6.3v. 2a., 0-8.6.3v. 2a. 51.55
260.0-250v. 100mA, 6-3v. 4a., 0.5.6.3v. 3a. 52.45 300.0-300v. 100mA, 6-3v. 4a., 0-5-6.8v. 3a. 12.46 Standard Pentode 6.000 R or 7,000 0 to 8 0 blip 6a, 88p.
300.0-300v. 100mA, 63v. 4a., 0-8-83v. 3a. 18.46 300-0-800v. 130mA, 6.3v. 4a., c.t. 6.3v. la. Push -Poll 8 watts EL84 to 3 nor 16 0.. 96p SMOOTHING
300.0.300v. 130mA, 6.3v. 4a. c.t., 63v. la. suitable for Mallard 610 Amplifier 82.85 Push -Pull 10 watts 6V6, ECL86 to S. 6, 8 or CHOSES
For Dullard 610 Amplifier 5295 350.0-350v. 100mA, 83v. 4a., 0-6-63v. 3a. 52.45 15 R SIM 150mA, 7-10H, 250
360.0-350v. 100mA, 63v. 4a., 0 5-6 3v. 3a 15.46 360.0-350v. 150mA, 8.3v. 4a., 0-6-63v. 3a. 62.85 Posh -Pull EL84 to 3 or 16 0 10.12 watts 9160 O 77p; 100mA,
360.0-350v. 150mA, 6 -Sv. 4a., 0-5-63v. Sa 82.96 Push-Pull Ultra Linear for Dullard 510, etc. 9245 10H, 200 0 800:
420.0-425v. 200mA, 6 -Sv. 4a., c.t., 5v. Sa 15.46 FILAMENT or TRANSISTOR POWER PACK Push-Pull 15.18 watts, sectionally wound 80mA, 10H, 350 n
426-0.425v. 200mA, 6 3v. 4a., 8 3v. 3a., 5v. Typo 6.3v. 1.5a. á6p: 6-3v. Sa. 50p; 6-3v. 3a. 85p; BLS, KT66, etc., for 3 or 16 n 82 20 Up; 80mA, 10H,
3a 56.00 6.3v. 6a. 6166; 12v. la. á1p; 12v. 3a. or 24v. Push -Pull 20 watt high quality eeetionally 400 0 ISp.
450.0-460v. 250mA, 83v. 4a., cet., 5v. M. 16.00 1.5a 6160 :0.9.18v lta 11ß6: 0.12-25-42v 2111.95. wound ELS4, 6L6, KT66 etc. to 3 or 15 fi 9966

R.S.C. MkIII SUPER 30 HIGH FIDELITY STEREO AMPLIFIER 'YORK' HIGH-FIDELITY 3 SPEAKER SYSTEM
BUILD AN AMPLIFIER WORTH APPROXIMATELY * Moderate size only 25 x 14 x 10in.
DOUBLE THE KIT PRICE INCLUDING CABINET approx. KIT
Only high grade components by leading manufacturers * Response 30-20,000 c.p.s. COMPLETE
Push Button Selector Switching
Jack Socket for Headphones
For Magnetic or
Ceramic Pick -Ups *
Impedance 15 ohms
Performance comparable with
£2525
Neon Indicator regardless of Price. units costing considerably more Carr. 65p
Satin Silver Finish Metal Fascia Output (per than-
Solid State Circuitry nel) 15 watts RMS COMPLETE KIT Consists of (I) 12in. 15 watt Bass
Twenty Silicon Transistors into 8/2,. Fre- (less cabinet). unit with cast chassis, Roll rubber cone surround
Four Diodes, Four Rectifiers
£27 quency Response Carr. 70p. 50 for ultra low resonance, and ceramic magnet.
Send S.A.E. for 7 Hz to 70 KHz Cabinet if req. (2) 3 -way quarter section series cross -over system.
full descriptive leaflet. ± 11 dB. £5 extra. (3) 8 x Sin. high flux middle range speaker.
R.S.C. STEREO FM III TUNER. FACTORY BUILT UNIT INC. (4) High efficiency tweeter. (S) Appropriate quantity acoustic
in cabinet CABINET with 12 months' guar- 112.500.50 damping material. (6) Handsome Teak veneered cabinet.
Visually matches antee. Or Dep. £7 and 9 monthly 1,ú (7) Circuit and full instructions. Terms: Dep. £4.60 and
Super 30 Mk. III £37.50 payments £4.54 (Total £47.86). 9 monthly payments £2.64 (Total £28-36).

194
 PACKAGE OFFER TDI DISCO
GROUP/DISCO UNITS Units listed below
(a) 100w POWER AMPLIFIER
(b) PAIR OF HI-FI HEAD-
PHONES
CONSOLE
50 WATT 100 WATT 50 WATT (c) MATCHING DYNAMIC Incorporating twin Garrard SP26
AMPLIFIER SPEAKER Mk.IH turntables and Semitone or
SPEAKER 'MIKE' (attached to h'phone) Acos Cartridge, with diamond styW.
(d) PAIR SO WATT SPEAKERS Separate Vol. controls for each
Black Rexine covered turntable. Also MONITORING
Cabinets Size approx. FACILITIES, plus Treble and Bus
18"x 18" x 8" Controls. Separate input for 'mike'
(e) RSC TDI DISCO CONSOLE with vol. control switch. Black
Vynide covered Cabinet with lid.
(a) (b) (e) (d) ! (e)
Carr. £250 £1
seeon illfell
onlett
radon
45 Or Dep. £10 and g63.26
9 mthly pymt. £6'80
Terms Deposit £30 and 18 monthly (Total £71 20) Carr. £1.60
payments of £800 (Total £17400).

HEADPHONES FANE ULTRAHIGH LOUDSPEAKERS

MICROPHONE TWIN TURNTABLE POWER
WITH PRE -AMP All power retinae are R.M.S. continuous. 2 YEARS' GUARANTEE
High flux ceramic magnets. ALL CARRIAGE FREE.
R.S.C. COLUMN SPEAKERS IDEAL FOR VOCALISTS
AND PUBLIC ADDRESS
'POP' 100 'POP' 60 'POP' 50
All types 15 Ohms covered in Refine and Vynatr
TYPE C4100 IS ALSO SUITABLE FOR BASS GUITAR OR ELECTRONIC ORGAN 18" I00Watt 15" 60Watt 12" 50 Watt
TYPE 0818 60 WATTS Low feedback 14,000 gauss 14,000 sause 13,000 gauss
TYPE C132 30-40 WATTS Fitted two characteristic.oneh Fitted three 13" x 8" deep 8/150 8/150 150
E11.99
exceptionally efficient, low feedback howl char- cone high flux speakers with high power £25.95 £ 14.75
acteristic high flux 13" z 8.20 watt Dep 18 and 9
speaker,. Term.: Dep. £8 and 9 £21 95 voice coils. Size approx. 54" x 14" x 11".
Dep. & 9 mthly pymte 68.54
Dep: £6 and 9 Dep. 68.30 and 9 monthly pay -
mthly payments 68.42 (Total 12478) Carr. 65P. (Total6568889) £32.72
1 Carr. 85p. thly payments monthly payments. meets 61.88
£2.49 (Total 228.41) 21.50 (Total 618.80) (Total 618.97)
TYPE C4I 00 100 WATTS Inc. four 12' 60 watt speakers for conserva- 1.50 PAIR SUITABLE
rive rating. Extra heavy construction. Size approx. 58 x 16 x 10' Acoustically E7 FOR BASS GUITAR, ELECT. ORGAN, ETC. ALL PURPOSES
filled and pree.nrised. Terms: Dep. 211 and 12 mthly. pyte. 65.80 (Total 688801. Carr. £1.50

R.S.C. A10 30 WATT ULTRA LINEAR FANE SPEAKERS `POP' 25/2 12 in. 25 WATT
HI-FI AMPLIFIER output, Hum level -70dß. Response Dual
Highly sensitive. Push -Pull high Cone 15 Q (for uses or Dep. 61.26 and 9
other than Bass Guitar or / `fl! mthly
£7.95
payments 89P
(Total £928).
rY1

t3dB c/e. All high grade component,. Valve. EF88

30-20,000 Electronic Organ). Carr. free
EF86, ECC83, EL34, EL94, 0Z34. Separate Bass and Treble
Controls. Sensitivity 38 millivolts. For High Impedance micro-
phones. For Clubs, Schools, Theatre., Dance Halls, Outdoor Func- GROUP/DISCO EQUIPMENT PACKAGE OFFERS
tions, etc. For Electronic Organ, Guitar, String Bau, etc. Gram.
ltadio or Tape. Two separate inputs with vol. controls permit such as "mike" and ,rlr F.A.L. PHASE 50 MK.III AMPLIFIER 637.95 PACKAGE: PRICE
Pick-up etc. for mixing purpose., 200-250v. 60 c/s A.C. mains. For 3 and 15 ohm L /rY1 PR. FANE POP 25/5 86W L/SPEAKERS
speakers. Twin -handled perforated cover 4810. 12 MONTHS' GUARANTEE. Carr. 72p £21
TERMS: Deposit f4 and 9 monthly payments of £8.27 (Total 024.43). Send S.A.E. for leaflet.
Terme: Deposit 67.60 and 9 montitlY
payments of 66.86 (Total 666.74)
6g g.g E4950£ïo
F.A.L. PHASE 60 MX.MI AMPLIFIER 187.96 PACKAGE PRICE
LINEAR T40/60D 50W GROUP/DISCO AMPLIFIER PR. PANE POP 60 L/SPEAKERS 628.98
0
* Term.: Deposit 610 and 9 monthly ,X57.50£=
* PULL
MONITORING FACILITIES payments of 16.07 (Total 684.88) 161.98
Individual Baas and Treble controls £54.45
* Twin lack output sockets for speaker. F.A.L. PHASE 60 MK.m AMPLIFIER 687.96 PACKAGE PRICE
* Or Deposit £7.60 A.,
Input sockets for medium or high impedance PAIR L18/20 86W L/S in cabinets 129.80
and 9 monthly Term.: Depoalt 610 and 9 monthly 461 'Al
*
Microphones or Guitar P.C. and Crystal or
Ceramic Gram. P.U.
Frequency response 30-20,000 Hz.
payments 66.00
(Total 66160) 4949,º-° payment. of 68.62 (Total 668.68)
LINEAR T40/60D AMPLIFIER
664.85
PACKAGE PRICE
* Output overload protection plus double tuning PAIR 112/20 SPEAKERS in Cabinets 654-46
62880
FRONT PANEL (Jack inputs) Gram, Gram, Microphone/
Guitar P.U.; plu. monitoring (socket.
Simulated black rexine, plastic
bonded metal case.
Terme Deposit 610 and 9 monthly
payments of £8.80 (Total £8470) 680 76
£75 caer. 61.60
CONTROLS Vol. (1) (2) (3) and (4). Bas., Treble, Master Vol., ALSO STOCKED -LINEAR F.A.L. PHASE 100/2 AMPLIFIER PACKAGE PRICE
Monitor Selection Switch Gram (1) or (2), Mains Switch. T80/100D X76.72 669.86
4 FANE POP 60 L/SPEAKERS 647.98
FAL PHASE 50 Mk,III AMPLIFIER 50 WATT.
Terme: Deposit 620 and 12 monthly
payments of 68.68 (Total 5128.58) 1117.81
í11O Q-r.
Solid state. 4 Separately controlled inputs Plue master vol.
control. Ind. Bass and Treble Controls. Protective circuit to
guard agaimt damage from accidental shorts. Output for
HIGH QUALITY LOUDSPEAKER UNITS
Speaker/s 3 to 30 ohms. Size ir x 7" x 74'. 200-250v. A.C.
mains. Output 60 watts music rating.
ALL TWO TONE REXINE AND VYNAIR FINISH
L125 50 WATT Fitted pair of 12" 50
Or deposit 6725 & 9 monthly pay- /
£37.95
U{ UY Carr. watt high flux speakers for conservative 5
mente 23-9E.'Total male.
64 82p. rating. Impedance 8-15 ohms. Carr. £1.50
Or deposit 6460 and 9 monthly payte. of 64.27. Total 14893
Combined SOW Amplifier
RSC PHANTOM '50' and 12ín, Loudspeaker.
For Lead Guitar, Ric., Gram, Radio. Tape (Not for use with Baas
L12/20 12" 20.25 WATT 13,000
lines 16 ohme
Dep 6250 & 9 £13.15
112/10 10.16 Watt veneer
finish cabinet 12" unit 8-16
ohm. Size appro.. 14" x
instruments). Inc. 3 input. and 2 vol. controls plus Treble, Base and Preesnce. mthly ºrats 214E 14" x 9". Carr. 50p £8.25
Output Jack for additional 16 ohm Speaker. Attractively finiohed in black with (Total 215 28) Ca.
rr 55p.
eilverflnished fascia and trimmings. Compact sloe. Fitted carrying handle.
CREDIT TERMS AVAILABLE ON PURCHASES OVER
Terms: Deposit 6895 and 12 monthly
£8 (Kits Excepted) INTEREST CHARGES REFUNDED
payments 6489 (Total 68788). Carr. Free
SAE for leaflet UK Mainland
ONLY £59.95
ON CREDIT SALES Settled in 3 months
NOW FIVE NEW BRANCHES R.S.C. Branches operate a 5-day week
RSC BASS -REGENT 23 DEANSGATE open Open all day Saturday
BOLTON
50 WATT AMPLIFIER shortly BRADFORD 10 North Parade (Closed Wed.). Te1.25349
19/19A MARKET BOLTON 23 Deansgate Tel: 33512 opens shortly
A powerful high quality all-purpose unit
for lead, rhythm, bass guitar, vocalists,
NOTTINGHAM STREET BIRMINGHAM 30/31 Great Western Arcade,
gram, radio, tape. Peak Output rating. Tel. 021-238 1279 (Closed Wed.).
Loudspeaker unit either horizontal or SUNDERLAND 5 MARKET SQUARE COVENTRY 17 Shelton Square, The Precinct
vertical mounting. DERBY 26 Osmaston Rd., The Spot (Closed Wed.).
* Two extra heavy duty 12in. 50w STOCKPORT 8 LITTLEUNDERBANK Tel. 41391
Loudspeakers. DARLINGTON
* Four Jack inputs and two Volume COVENTRY 17 SHELTON SQUARE 19 Northoste (Closed Wed) Tel 08043
Controls for instant use of up to four EDINBURGH
pick -ape or "mike.". Bass and Treble NEW LARGER PREMISES AT HULL, Lothian Rd. (Closed Wed.). Tel. 229 9501
101
controls. Send S.A.E. for leaflet.
Credit Terms: Deposit 115 DARLINGTON & NEWCASTLE Áäd GLASGOW 328 Argyle St. (Closed Tues.).
& 9 monthly payments of 71 Tel. 248 4158
67.22. (Total 67998.1 Carr. £2 £ 1 1 50 HULL 7 Whitetriergate Tel. 20505
LEICESTER 32 High Street (Closed Thurs.). Tel. 58420
RSC GP30 HI-FI LEEDS 5-7 County (Mecca) Arcade, Brim/ate
(Closed Wed.). Tel. 28252
AMPLIFIER LIVERPOOL 73 Dale St. (Closed Wed.). Tel. 2383573
For Guitar, Vocal or LONDON 238 Edgware Road, W.2. (Closed Thurs.).
HI-FI CENTRES LTD. Tel. 723 1629
Instrumental Group
A 4 Input, 2 vol. control Hi -Fl
MAIL ORDERS & EXPORT ENQUIRIES TO:
AUDIO HOUSE, HENCONNER LANE, LEEDS, 18.
- MANCHESTER 60A Oldham Street, (Closed Wed.).
Tel. 238 2778
30 watt unit with Separate Base Tel: Pudsey (09786) 77881. MIDDLESBROUGH 106 Newport Rd. (Closed Wed.).
and Treble controls. Current NEWCASTLE UPON TYNE Tel.47098
TERMS C.W.O. or 0.O.D. No O.O.D. under 61.
valves. Peak output rating. POSTAGE 88p EXTRA UNDER SE. 33p EXTRA 24 Newgate Shopping Centre (Closed Wed.). Te1.21469
Strong Rexine covered cabinet with OVER 68 OR AS QUOTED. TRADE SUPPLIED. NOTTINGHAM 19/19A Market Street (Closed Thurs.).
handles. Attractive black/silver P.V.C. fascia. Tel: 48068
For 0v. A.C. mains. For 3 or 16 ohm S.A.E. PLEASE WITH ENQUIRIES. SHEFFIELD 13 Exchange Street (Castle Marke' Bids.)
speakers. Send B.A.E. for leaflet. Terms:
Deposit 14-40 and 9 monthly payment. of
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/%/Neon
Carr. SUPPLIERS TO GOVT. DEPTS. H.M. FORCES.
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195
 TERMS Retail mail order subject to £1.00 minimum order.
Cash with order only. Trade and educational establishments
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Postage 10p inland. 25p, Europe.
GUARANTEE: All goods carry full manufacturer's
warranty. Get in touch today for a complete SCS COMPONENTS, P.O. Box 26,
run-down of devices available from SCS (include SAE). Wembley, Middlesex HAO 1YY
The 'Professional' Amateur Supplier

device of the month ZN414 compatible device

- 5,60:0,250 The Ferranti ZN414 is a complete a.m.
MFC 40006
The Motorola
4,75 0,15 0
radio circuit which operates -1-Watt Audio
4,83 from 1.1 to 1.8 volts and requires Amplifier is
+0,51
only battery, earphones and antenna designed for the
output stage of
plus a tuning capacitor and two battery powered
decoupling capacitors. The ZN414 portable radios.
0,76
MAX
* 250 mW o Audio Output Power
features: medium and long waveband, * Low Standby Current- 3.5 mA typical
12,7
MIN good stability on assembly, no * Low Harmonic Distortion
*
-1- -0,483 0 setting up of IF coils, plus
Reduces Component Count in
Portable Radios by Two Transformers
and Two Transistors
much more.
* Eliminates Costly Component
Matching Requirements

motorola 114 watt

a complete a.m radio circuit for just audio amplifier
M FC 4000

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196
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197
 A special
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NEW STEP[NSPEAKERS
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TEST D!r GU RATE D!
DAF9l, DF91, 1)891, DL92, DL94.
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Tuesday June 12th, Wednesday June 13th, 6AT8 .00 35W4 £6 50581 .39 KT68 .78 PL83 88 UF89 80
6AU6 80 96240T .25 ECH83 .38 LN319 68 PL84 .30 111.41 58
Thursday June 14th. Send this coupon now for BBAB .80 500D80 .88 ECH84 85 LN329 @0 P1600 .58 131.84 .80
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the full INTERFACE 73 story and invitation... 61316 .41 AC/VP2 77 ECL82 .29 N78 £1.06 PM84 .30 UY41 .80
.60 E349 70 ECL88 83
... To Texas Instruments Ltd., Seminar Centre 6BW7
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12AU7
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81 DK98
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Company SOC16 .58 EAF42 .50 01.000 68 P0F808 66 01261 41 0081 .12
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READERS RADIOILFORD,
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PW PRICES ARE INCLUSIVE OF VAT, ONLY POSTAGE IS EXTRA
Minimum post/packing on I valve 7p., on each additional valve,
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Any parcel i naured against damage in transit Sp extra.

198
tate Tate 4-channel equipment decodes all quadraphonic

4channel matrix records and broadcasts and adds dimensional

realism to ordinary stereo programme sources. It also
controls 4 -channel tapes when played through your
system and CD -4** records when used with a

decoder separate demodulator.

They are characterized by their ultra low distortion
characteristics and six -pole wideband phase shift
networks.These combine to produce an acoustic

modules performance giving highly articulate sounds from the

back as well as the front channels.The amplitude
accuracy is better than ±1dB from 5Hz to 100KHz.

High definition SQ* quadraphonic decoder

Fully built home constructor module
features: exclusive wide band phase shift net-
work; distortion typically 0.04%. Ideal for use
with other kit projects and even with the world's
finest amplifiers.
Recommended retail price (excluding VAT) £12.95
Dimensions: 85 x 60x 25mm
Operating Voltages:18-30VDC at lima

High definition SO* quadraphonic decoder

Fully built home constructor module
featuring wide band matrix decoding circuit
board with integrated power supply, switching,
master gain and exclusive rear level control.
Recommended retail price (excluding VAT) £21.95
Dimensions: 165x140x26mm
Operating Voltages 110-240VAC at 3watts
:

Specifications The only way to really understand the difference

Input Impedance 40KOhms between ordinary stereo and SQ Quadraphonic sound
<3000hms is to hear it. However, if you remember the difference
Output Impedance
20Hz-18KHz
between mono and stereo upon hearing it for the first
Phase Shift Network 90110'
time, multiply the recollection of that experience by a
Nominal Gain Unity factor of ten and you will be able to appreciate what is
Frequency Response ±1dB 5Hz-100KHz in store for you when you first hear SQ Quadraphonic
Nominal Input Level 250mVrms sound.
Nominal Distortion 0.025% r
2.5V rms Please send tate 2 at £14.25 each (including VAT)
Clipping Point
Distortion before Clipping 0-08% max. tate4 at £24.15 each (including VAT)
Front Separation >60dB I enclose cash /cheque/money order
Rear Separation >20dB Name (BLOCK LETTERS)

Tate Audio Transmission Equipment Limited Address

5-7 Covent Garden Cambridge CBI 2HS England Reg. No. 105 9684
Telephone 0223 67873 Telex 81640
PW73
*TM CBS Inc. **TM Victor Japan J
199
 OWS GMLSMIIN6r.0(nnoolliO
ET
ETER
MULTIM

H igh -precision at low-cont.

U43I2 MULTIMETER
Extremely sturdy instrument for g...war
electrical use. 887 o.p.v.
LB3 TRANSISTOR TESTER
Tests ICO and B.
PNP / NPN. Operates
MODEL L-55 FET
V.O.M.
Ranges: D.C. 10V, 150V, 0/-3/1.6/75/30/60/160/300/ from 9v battery. Com- Input impedance 111 mrg
1.000V (10,000 opv). A.C. 800/900 VDC and 75n,V. plete with all in- ohms.O/-3/1.2/6/30/
10V, 100V, 100V (1,000 0/3/1.6/7.6/30/60/160/300 struction., etc. 1896. 120 / 600V. D.C. 0 / 3 /
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Resistance 100k ohms. 0/300µA/1.6/6/16/00/160 0 / 120µA / 120mA D.C.
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0/1.6/6/16/80/100/600MA/ KAMODEN HM.350 TRANSISTOR TESTER /100 meg ohms
AUDIOTRONIC MODEL ATM.1
1.6/8 AMP. AC. High quality instrument 115-97. Poet 151r.
0/200n/3K/30K Q. to teat Reverie Leak
Top value 1000 o.p.v. Accuracy DC 1%. AC 13%. current and DC current.
pocket multimeter. Knife edge pointer, mirror scale. Comp ete Amplification factor of KAMODEN HMG -500 INSULATION
Ranges: 0/10/50/250/1000v. with sturdy metal carrying cane, leads and NPN, PNP, translators, RESISTANCE TESTER
AC and DC instructions. 19.60. P. a P. 20p. diodes, SCR's etc. 4" x Range 0-1000 Meg.
DC Current 0-1mA/100mA. 41" clear scale meter. ohms, 500 Volt.
Resistance 0/150k ohms. HIOKO MODEL 700X Operates from internal Battery operated.
Decibels -10 to +22dB. 100,000 O.P.V. Overload batteries. Complete with Wide range clear
Size 90 x 80 x 28mm. protection. Mirror scale. instructions, leads and meter 45e x 4".
Complete with teat leads. 8/611.2/1.6/3/6/12/30/00/ carrying handle. 11860. Complete with de-
18.50. Poet lop. 120/300/600/1200V DC Poet ß0p. luxe carrying case.
1 6/3/0/12/30/00/160/300/600 batteriee, instruc-
1200 V. A.C. tions. 11895. Post 3Up
15/80µ43/6/80/80/150/300or.V MODEL 449A IN
MODEL 1092 CIRCUIT TRAN-
TESTMETER 6/12 AMP. DC. 2K/200K/2 BELCO AF-SA SOLID STATE SINE
0,000 O.P.V. Meg/20 Meg ohm -20 to SISTOR TESTER SQUARE WAVE C.R. OSCILLATOR
+83dB. 118.50. P. a P. 20p Checks true A.C. Rine 10x200,000 Ile: Ngnere litv 50,000 Hz
0)3/16/150/300/1200 V. beta in / out. Check.
D.C. 0/6/30/300/800 V. Icbo. Checks diode. Output max.
A.O. 0/30044A/300 MA
MODEL C-7080 EN
Giant 8 mirror scale. In / out. Checks
O + 10 dB.
0/10K/1 mega (10 K ohne)
20,000 o.p.v. 0 / 25 / 1 / SCR, etc. Beta Operation In-
Decibels -10 to +16db 2.6/10/50/260/1000/ HI 10 - 500,
6$76 each +15p P. a P. ternal batteries
6000V. D.C. 0 / 2.6 / 10 / LO 2 - 60.
Iebo 0-600044A. 220/240 V A.C. Attractive '2 -
50 / 260 / 1000 / 0000V. operation 117-50. Poet 26p. tone mere 71
LT601 A.C. 0/50µA/1/10/100/
MULTIMETER 6' x
600mA / 10 amp. D.C. MODEL U431 I SUB -STANDARD MULTI- Price 11760.
New style 20,000 O/2K / 200K / 20 meg RANGE VOLT AMMETER Carr. 174p.
o.p.v. pocket multi -
meter. 6/25/60/260/
- 20 to + 60 dB.
81295. Post 35P.
tSensltivlty 330 ohms/Volt
AC and DC. Accuracy CI.5 PULSE
300 / 2500 V. D.C. 5% D.C. 1% AC. Scale
10/50/ 100/ 600 / 1000V. 370 WTR MULTI -METER length 1135mm. 0/300/7504A / OSCILLOSCOPE
Features A.C. current ranges. For display of polo,')
A.C. 60µA / 250mA. 8K / 0
meg ohm.. -20 to + 22dB.
6276. Poet 205.
20,000 o.p.v. 0/5/26/10/50/
250/600 1000 V. D.C.
10/2.5/10/00/260/600/1000V AC
1.6/3/7.6/16 30/76/
160/ 900 / 760mA / 1.6 / 3/
7-6AMP DCO/8/ 7.6/ 15/
30 / 76 / 160 / 300 /
and periodic waveforms
in electronic circuit.
VERT. AMP. Band-
g
eº
, !]>-
k
s
e
MODEL TH-I2 0/60uA/1/10/100mA/1110 Amp width 10MHz. Benei -
D.C. 750mA / 1.6 / 8 / 7.6 tivity at 100KHz VERB/
20.000 o.p.v. Overload pro-
tection. Slide switch selector 0/100mA/1/10 Amp AC AMP AC O/76/160/ mm. -1.26; HOR. AMP. Bandwidth 300K Hr.
0/5K/50K/500K/5 MEG/ 60 300 / 760mV / 1.5 / 3 / Sensitivity at 100K Hz, V RMS/mm. -3.26:
7.6 / 16 / 30 1 76 / 160 / 800 / 750V DC Preset triggered sweep 1-3,000usec.: free
1 llC O /160/20/000v
0 /6 6 MEG.
-20 +82db. 0/760mV / 1.6 / 8 / 7.6 / 16 / 30 75 / 150 / 800 running 20.200,000H. in nine ranges.
1000V. A.C. 0 / 60µA / 26 / /750V AC. Automatic cut out. Supplied oo u-
250mA. D.C. 0 / 3K / 80K / 115. P. a P. 25D. Calibrator pips. 220 .< 380 x 430mm.
plete with test leads, manual and test certifi- 116.230V. AC operation. 18200. Carr. pall.
300K / 3 meg -
20 to + 60dB HTIO0B4 MULTI-METER cates. 149.00. Post 60p.
64.97. Poet 15p. Features A.C. current ranges. TO -3 PORTABLE OSCILLOSCOPE
100,000 o.p.v. Mirror Scale. TE -65 VALVE VOLTMETER 31n. tube, Y amp. Sensitivity
RUSSIAN 22 RANGE MULTIMETER Overload protection. 28 ranges. D.C. volt. 02v p-p/CM. Bandwidth
Model 17487 10,000 o.p.v. 0/6/2.6/10/60/260/600/1000 V 1.5-1,500v. A.C. volte l.6 cps -1.6 MHz. Input Imp.
A first class versatile in- D.C. 1.5-1,500v. Resistance up 2 meg Ll 26pF X amp.
strument manufactured In 0/25/10/60/250/1000 V. A.C. to 1,000 megohms. 200/ sensitivity 0.9v. p-p/CM.
U.S.S.R. to the highest 0/101260µA/2.6/26/260 MA/ 240v. A.C. operation. Bandwidth 1.5,ps-500kIlx.
etaodards. Ranges: 9.5/10/ 10 Amp. D.C. Complete with probe and Input Imp. 2 meg n 20pF.
60/250/600/1000v D.C. 2.6/ 10 Amp A.C. 0/20K/200K/ instructions. Time base. 5 ranges 10 cps
10/50/2501500/1000v A.C.
Current 100wA/1/10/
2 MEG/20 MEG. -
20+62dB. 117-50. P. a P. 90p. 300 kHz. Synchronization.
110 11.60. P a P. 26p. Additional probes avail- Internal /external. Illuminated
100mÁ/1A. Resistance able: R.F. 18.185; H.V. scale 140 x 216 x 380 nun. Weight 15116.
300 ohms/3/30/300K/8m n. KAMODEN 72.200 00.60. 220/240V. A.C. Supplied brand nrw with
Complete with batteries. MULTITESTER handbook. 14760. Carr. 50p.
teat leads, instructions and High sensitivity teeter. KAMODEN HM. 7208
sturdy steel carrying case. 200,000 0.p.v. Overload pro- F.E.T. V.O.M.
RUSSIAN C1.16 DOUBLE
OUR PRICE 66.97. P. & P. 21p tection. Mirror scale. Rangea: Input impedance 10 mrg
BEAM OSCILLOSCOPE
0/06/-3/3/30/120/8001 ohms.
6 me/e PassBand. Separate
1200V. D.C. Ranges:
HIOKI MODEL 730X 0 / 8 / 12 / 60 / 300 / 11,200V. 0 / 26 / 1 / 2.5 / 10 / 50/ Yl and Y2 amplifiers.
30,000 O.P.V. Overload A.C. 260 / 1000V. D.C. Rectangular 51n. x HO.
protection. 6/30/60/300/ 0/8µA/ 1.2mA / 1201nÁ¡ O / 2.5 / 10 / 50 / 2130/
C.R.T. Calibrated trig-
000/1200 VDC. 12/60/120/ 600mA / 12A. D.C. 1000V. A.C. gered sweep from 2 Weer.
000/1200 VAC. 80//4A/30 0 / 12A. A.C. 0/25µA /9.5 /25/260 to 100 mull -sec. per cm.
mA/300 mA. 2K/200K/2 -20 to +83dB. 0 /'2K 1 200K / 2 meg / MA D.C. Free running time base 60 c/c -I mr/n. líuilt-
negohm. -10 to +113d1..
1660. P. a P. 15p.
200 meg ohms. 81606. Post 80p. - 20 to + 82dB
0/ 5K / 50K / 500K / 5meg
In time base calibrator and amplitude
calibrator. Supplied complete with all
TMK LAB TESTER. 500meg ohms. accessories and Inatrnetinn mantel
MODEL P1.436 100.000 O.P.V. 81hr. 114-96. Poet 30P 487. Cart. Paid.
'20k 0/Volt D.C. 8k 0/ Scale Buzzer Short Cir-
cuit Check. Sensitivity MODEL AT201
volt. AC. Mirror male.
100,000 O.P.V. D.C. 6K/
TE -40 HIGH SENSITIVITY DECADE
8/3/12/30/120/800 V
Volt A.C. D.C. Volte: A.C. VOLTMETER
11.C. 3/30/120/600 V ATTENUATOR
A.C. 60/800µA/60/600 3, 2.6, 10, 60, 260, 1,000 10 meg. input 10 range.: Frequency range O
mA. 10/100K/1 Meg/10 V. A.C. Volta: 3, 10, 25. 01/'003/-1/3/1/3/10/30/100/ 200KHE. AttentaN,r
]leg n -20 to +48db. 60. 260, 500. 1,000V. 900V. R.M.S. 4cpe: 1.2 Mc/a. 0-111db, 0.1db step.
66.97. P. a P. 129. D.C. Current: 10, 100µA. Decibels -40 to +50dB. 600 ohms. MI
10, 100. 500mA, 2.6, 10 amp. Resistance: Supplied brand new complete Max. Input power
1K, 10K. 100K, lOME6, 100Mß6 n. with leads and inetruetlone. 80dbm. Size 180 x 90 x 55mm.
MODEL S00 Decibels: -10 to +49 db. Plastic Case Operation 290V. A.C. 117-50. 11860. Pout 87p.
30,000 O.P.V. with over- with Carrying Handle. Size: 74m. x13510. x Carr. 26p.
load protection mirror scale 31ín. 118.95. P. a P. 26p. ARF-300 AF/RF SIGNAL GENERATOR
o/0/2.5/10/2ó/100/200/000/ TIE MODEL 117 F.E.T. ELECTRONIC All traneistorlxd,
1,000v. D.C. 0/2.6/10/26/ Model 5-100TR MULTIMETER' VOLTMETER compact, fully port-
100/250/500/1,000V. A.C. TRANSISTOR TESTER Battery operated, 11 able. AF sine wave
0/60µA 6/60/600mA. 12
amp. D.C. 0/80/K/13 Meg./
100,000 o.p.v. mirror hale/
overload protection. 0/.12/ NMI meg input, 26 ranges.
Large 41" mirror scale.
18 Hs to 220 KHz.
AF square wave 18 Hz
60 Meg L-1
8887. Poet paid.
6/3/12/80/120/800 V DC.
0/8/30/120/800. V AC. 0/12/
She sr
x 44" x 21".
DC VOLTS 0.3-1200V
to 100 KHz. Output
sine / square 10v.
800µA/ 12/300mA/12 AMP AC VOLTS 3-30017 P -P. RF 100 KHz to
HIOKI MODEL 750X DC. 0/10 K/1 MEG/100ME0. EMS. 8.0-800V P.P. 200 MHz. Output 13.
60,000 o.n.o. 43 ranges 0-0.8 -20 to +50db. 0.01--2 MFD. DC CURRENT -12- maximum. Operation
to 1.900v D.C. 0-3 to 1,200v Translator teeter measures 12MA. Resistance up 220/240v. AC. Com-
A.C. 0-30µA/800mA. 0-3K/30 Alpha, beta and Ieo. Complete to 2000M ohm. Decibel. -20 to 1- lidli. plete with Instruction.
meg ohms. - 10 to i 174E. with batteries, instruction. Complete with leads/Instructions. 11750. and leads. 689.96.
8297. Post 201. an,) leads. 81850. P/P 25p. P. & P. 20p. Pont 50p.

200

www.americanradiohistory.com
 TE -20D RF SIGNAL GENERATOR

Accurate wide range signal

generator covering 120
.SEW CLEAR PLASTIC PANEL METERS
Kehl 500 Mc/e on 8 bande.
Directly calibrated
able R.F. attenuator, audio
Vari- USED EXTENSIVELY BY INDUSTRY, GOVT. DEPTS., EDUCATIONAL
output. Xtal socket for AUTHORITIES, ETC.
calibration. 220/240V. A.C.
Brand new with inetruc-
bone £16. Carr. 379p
Over 200 ranges in stock -other ranges to order. Quantity discounts available.
Sine 140 x 215 x 170 men. Send for fully illustrated brochure.

Type SW.I00 100 x86 mm.. Type MR.85P. 4Lin. x 41in. fronts Type MR.38P. 1 21 32in. square fronts
TE22 SINE SQUARE WAVE 60µA 2415 60mA .... 68.10 200mA .... 2226
AUDIO GENERATORS 60-0-60µA 9895 100mA .... 1810 900mA .... 22 25
Sine: 20cpe tu 200 100µA £395 SOOmA .... 9810 500mA .... 9286
760mA ....
.

kc/s on 4 bande. 100-0-10000A 9890 1 amp 9810 V 22.25

Square: 20cpe to 30 600µA 9870 5 amp 1830 ..' 1 amp £225
er r',
.

kc/e. Output impe- lmA 9860 a 18 . 2 amp £226

£226
dance 6,000 ohm..
200/250V. A.C. op-
eration. Supplied
20V. D.C.
60V. D.C.
300V. D.C.
98.80
23.60
2860
5amp. D.C.
300V. A.C...
2380
28.70
3016 ampmp.
20V. D.C.
50V. D.C.
£3.8010
9810
2340
-AI- '
6 amp
10 amp.
3V. D.C.
62'26
92'26
brand new and 1 amp. D.C. 9880 VU Meter .. 24.30 5 µA 6896 150V. D.C. 9810 60µA £2 65 10V. D.C. £2'25
guaranteed with in- 50-0-50µA 2340 300V. D.C. 1810 50-0-600.A 2250 15V. D.C. £2.26
struction mm,ual 1000/A . 2840 11V. A.C. .. 23.10 100µA . 12.45 20V. D.C. 92.26
and lead.. 217.50. 100-0-l00µ.1 2830 300V. A.C... 9840 100-0-10Óµ4 9240 00V. D.C. 92'25
Carr. 375p. Type SD.830 82.5mm x 110mm Fronts 2310 6 MeterlmA 2815 200µA £2.26 100V. D.C. 9225
lOmA .... 23.10 600µA 1320 VU Meter .. £8.95 600µA £2.25 150V. D.C. 9225
80mA .... 63.10 600-0-200µA 2810 1amp. A.C. 1810 600-0-600µA 2225 900V. D.C. 12.26
100mA 1340 lmA 1310 5 amp A.C. 8810 ImA £286 000V. D.C. £226
" YAMABISHI " VARIABLE VOLTAGE 500mA 1840 1-0-1mA £840 10 amp. A.C. L8.10 1-0-1mA 22.26 750V. D.C. £226
TRANSFORMERS 1 amp 23 10 5mA 2810 20 amp. A.C. 2810 2mA £225 15V. A.C. 22.80
8 amp 98.10 10mA £8.10 30 amp. A.C. £340 5mA 12 20 50V. A.C. 22.30
Excellent quality at low coat. All uwdrle 10 amp. 13.10 10mA i2 86 150V. A.C 92.80
Input 230V. 50/60 te/s. Variable output 6Oµ4 1840 5V. D.C. 23.10 2 0mÁ 1825 300V. A.C 22.30
0-260V. 60-0-501 A 18.40 10V. D.C. 13.10 0mA 2226 200V. A.C £2.80
MODEL S-260 100µA 13.85 20V. D.C. L8.10 Type MR.52P. 21in. fronts B Meter lmA 12.80
GENERAL PURPOSE 100-0-100µA 18.36 50V. D.C. 28.10 80µA 2860 10V. D.C. .. £2 60 160mÁ 2 28
12.25 VU Meter 62.85
BENCH MOUNTING 200µA 2880 3001. D.C. LI -10 60-0-60µA LI -06 20V. D.C. .. £2.60
500µA 1816 15V. A.C. £8.80 100µA 4800
. 10V. D.C. .. 12.60
I Amp 2700 Im) 1810 300V. A.C £8.80 100-0-100µA 8295 300V. D.C. 1250
2.6 Amp 1806 13-10 VU Meter £8.50 600µA 12.60 15V. A.C. .. 22 80 Type MR.45P. tin. square fronts
lmA 8260 900V. A.C... 8280 60µA £270 6 amp 8240
5 Amp 91175 6mÁ £260 8 Meter 1mÁ 2280 £2'40
60-0-60µA 9285 10V. D.C.
ö Amp 21690
Type SD.640 63.5mm z 85mm Fronts 10mA 2260 VU Meter .. 28.80 100µA .... £280 20V. D.C. £240
10 Amp £2250 501nÁ £260 1 amp. A.C. £260 100-0-100µA 2260 20V. D.C. 12.40
l2 Amp
SOuA 2806 500mA 92.90 100mA £2.60 6 amp. A.C. £2.50 200µ4. .... 2260 300V. D.C. 1240
22860 60-0-5010A 1805 1 amp £290 500mÁ £2.50 10 amp. A.C. £250 600µA 22.46 15V. A.C. 22.40
20 Amp 14900 100µA ... £8.00 5 amp £2.90 1 amp 12 50 20 amp. A.C. £2.50
.
500-0-60010A L240 3001. A.C 22.40
100-0-10000A 6800 10 amp 42.90 6 amp 2260 30 amp. A.C. 12.50 1mÁ Meter lmA £260
26 Amp 25800 £2 40 S
200µA .... 13.00 8V. D.C. £290 6rA £240 VU Meter .. 62.70
40 Amp 28850 50000A .... £2.96 20V. D.C. 22.90 10mA £2.40 1 amp. A.C. 22.40
lmA 2890 60V. D.C. 2290 2840 5 amp. A.C. 12.40
MODEL á-260B 5mA 6290 300V. D.C. 6890 Type MR.65P. 31 n. x 31in. fronts 60mA
10 amp. A.C. 22.40
100mA £2 40
10mA 22.90 15V. A.C. .. 28.00 60µA 13.70 10V. D.C.
500mA £2 40 20 amp. A.C. 22 40
Panel Mounting. 00mA 12-90 300V. A.C... 6900 80-0-6000A LI 15 20V. D.C. .. £2 80
1 amp £2'40 30 amp. A.C. 98. 40
1 Amp .. 17.00 100mA 12-90 VU Meter 6815 100µA 1316 00V. D.C. .. £280
1 6 Amp .. 28.06 100-0-100µA L810 150V. D.C. 2260
200µA LI -OS 300V. D.C. 12 80
Tupe SD.460 46mm x 59.5mm Fronts 600µA £2.75 16V. A.C. .. 62.80 "SEW" BAKELITE
Carriage and 60µA 1280 1 amp 2280 500-0-60000A 2280 60V. A.C. .. 62.80
Packing Extra 60-0-60µA 1980 6 amp. 2260 lmA 92.80 100V. A.C. .. 12.80 PANEL METERS
100µA .... 1275 10 amp. £2 80 5mA £2.60 200V. A.C. .. £2 80
Type MR.65. 34in. square fronts
100-0-100µA £2.75 6V. D.C. £2 60 10mA 12 80 000V. A.C. 8280
l amp 6280
....
-
200µA 2270 10V. D.C. 12.60 50mA £280 8 Meter lmA 1886
.... 20V. D.C. £260 £2.80 VU Meter .. 28.70 5 amp £2 80
AUTO TRANSFORMERS 600µA 12.55 100mA
16 amp £2 60
lmA £9'80 50V. D.C. .. 22.60 500mA 22 60 SOmA A.C. £2
0/119/260V. Step up or step down. Fully 22 60 100mA A.C. £2 80 30 amp £280
6mA £2'80 300V. D.C. £2'60 1 amp
60 amp. 1280
shhrroonded.
lOmA £2.80 6 amp 12.80 200mA A.C. £280
BO W 2210 P. A P. löp £2.80 15V. A.C. .. £970 10 amp. £280 500mA A.C. £2.60 6V. D.C. 62.80
60mA 10V. D.C. 9280
150 W 2270 P. a P. 18p 100mA 12.80 300V. A.C... £9.70 15 amp. 82.80 1 amp. A.C. 2280
VU Meter .. 12.90 6 amp. A.C. £280 20V. D.C. £2
300 W £8.80 P. a P. 23p 600mA 22-130 20 amp. 12.60
00V. D.C. 22.80
W 2526 P. a P. 93p 30 amp. £280 10 amp. A.C. 12'60
600 £280 150V. D.C. L280
60 amp. L290 20 amp. A.C.
1000 W 2760 P. & P. 38p 6V. D.C. 2280 90 amp. A.C. £280 300V. D.C. £2 -SO
1600 W 21020 P. & P. 43p 25µA 44 80 60mV. D.O. £2 90
60f.A 2356 lOomV. D.C. £200
2260 W 61726 P. A P. 60p 60-0-5OµA £3-06 30V. A.C. LI -65
6000 W 135.00 P. & P. 21
US 101.
"SEW" EDUCATIONAL 100µA . £3.00 10V. A.C. £2.65
51/4
METERS 100-0-100µA 1300 200V. A.C. 22.86
600µA 9270 900V. A.C. 12.82
.c a0saavtt Type ED.I07. Size 600-0-60000A £8.70 000mA A.C. 22.80
MCA. 220 AUTOMATIC overall 100mm x lmA 1280 1 amp. A.C. 22.60
VOLTAGE 90mm x 108mm 1-0-1mA 8280 6 amp. A.C. £260
STABILISER A new range of high 5mA 22 80 10 amp. A.C. £280
Input 08 125 VAC or 176. quality
moving coil 10mA L280 20 amp. A.C. £2.80
250VAC. Output 120VAC "SEW" EDGWISE METERS instruments ideal 60mA 92-60 9O amp. A.C. 1280
or 240VAC. 200VA rating. Type PE.70. 3 11132in. x 1 15132in. x for school experi- 100mA £280 60 amp. A.C. 62 80
211.97. Carr. 50p. ment. and other 600mA 9280 VU Meter 13 65
21in. deep
60µA 2815 600µA .... 28 ß0 bench applications.
50-0-50µA £8.60 11mÁ 3' mirror scale. The
2820 meter movement le easily accessible to Type S-80 80 mm. square fronts
PS.200 REGULATED P.S.U. 100µA 2860 Available
100-0-10ÓµA 28.50 306V- A.C 28.26 demonetrate internal working. 80µw £860
Solid state. Variable output 200µA .... 28.40 VU Meter 28.86 in the following ranges: 60-0-60µA 2840
5.20 volt D.C. up to 2 amp. 2650 20V. d.c. .. £4.85 100µA 18.40
Independent meters to 60µA .

100µA 25.10 10V. d.c. .. £4185 100-0-100µA 2880

monitor voltage and cur- lmA 900V. d.c. .. 1485 600µA 28.06

-
14-85
rent. Output 220/240 V. 60-0-60µA 2610 lmA 2800
A.C. Sine 79' x 61' x 3i'.
119-96. P. a P. 26p.
MOVING IRON 1-0-1mA £4 85 Dual range
500mA/6A d.c. £5.10
20V. D.C.
50V. D.C.
13.00
21.00 6 amp. D.C. 68.00
1A d.c. £4.86
ALL OTHERS MOVING COIL 131. d.c. £4.85 6V/50V d.c. 66.10 300V. D.C. 2800 300V. A.C... 63.00
10V d.c £4.86 1 amp. D.C. 1800 VU Meter .. 6870
Please add postage
P5.10008 REGULATED
POWER SUPPLY 240° Wide Angle ImA Meters SEND SAE FOR LIST OF
POWER RHEOSTATS
Solid elate. Output 6, 9 MW 1.6 60mm square 6897 SEMI CONDUCTORS & VALVES
or 12 volt DC up to I High quality ceramic con- W 1-8 80enm square 64.97
amps. Meter to monitor truction. Winding. em-
ded in vitreous enamel. P. & P. extra
current. Input 220/240v ALL PRICES ARE
AC. Size 4' x 35' x 65'. envy duty brush wiper.
Continuous rating. Wide SUBJECT TO 10°ó VAT
61197. P. a P. 26p. ex -stock.
range available
Single bole fixing. Sin. dia.
shaft.. Bulk quantities avail- 230 VOLT A.C.
able.

5
230V/240V SMITHS SYNCHRONOUS 50 CYCLES
GEARED MOTORS 25 WATT. 10/26/60/100/260/600/1000/1600/
2500 or 5000 ohms. 969. P. a P. 10p. RELAYS
Built In gearbox. All brand
new and boxed. 90 RPM 50 WATT. 10/25/50/100/260/600/3000/2600 Brand new. a set. of
CW; RPH CW; 20 RPH
2 or 6000 ohms. 3185. P. A P. 10p. changeover contacts at
0W; 2 RPH ACW: 30 b amp rating. 50p each. INALSO SEE
ERH CW; P. a P. 10p (100 lots 240) FOLLOWING PAGES
100 WATT. 1/6/10/25/60/100/260/500/1000
p each Post 12p. or 2600 ohm.. 6196. P. a P. lbp. Quantities available.
60
201

www.americanradiohistory.com
 flUll G.W.SMIIH ICD(norn) ITA EMI LOUDSPEAKERS HOMER INTERCOMS DH -085 DE -LUXE STEREO
Model 350. 13" x 8" Ideal for HEADPHONES
with single tweeter/ home, Feature. unique
crossover. 20-20,000 office, mechanical 2 way
He. 15 watt EMS.
Available 8 or 15
stores, units and fitted
adjustable lever
factories, controls. 8 ohm im-
ohms. 47.25 each. etc. Sup-
4 Bands covering 550 kc/e-90 me/e
P. & P. 37p.
Model 450. 13" x 8"
plied
complete
pedance 20-20,000
cps. Complete with
B.F.O. Built -(n Speaker 220/240 v. with twlo tweeter/ with batteries, cable and free spring lead & etereo
A.C. Brand new with instructions. crossover. 55-19,000 instructions. jack plug.
Our
£ 15.75 Carr. He. 8 watt EMS. 2 Station 82 97, P. & P. 16p. Our tt P. P.
Price 37p
Available 8 or 15
ohms. 0662 each.
3 Station 4625, P. 8
4 Station 1682, P. &
P. 15p.
P. 17p. Price L7.97 30p
CASSETTE (P.
C835D Deck
& P. 50p)
.. .. £44 45
P. a P. 25p. CS35 Recorder .. £57 76
UR -IA RECEIVER
.

C835/C388 Speakers .. £6795

GXC4OD Deck .. £5720
4 -CHANNEL STEREO 0X040 Recorder £6720
.

SPECIAL OFFER I FM TUNER CHASSIS GXC4OT Deck/Receiver £9906

STEREO HEADPHONES 0X045 Deck .. £7825
SPEAKERS 6 TRAN- OXC46D Dolby Deck .. £8355
SISTOR 0X046 Recorder .. £8995
Matched pair HIGH GXC6OD Deck . .. £8785
of stereo book-
shelf speakers.
QUAL- TTC 03800. GXC66D Dolby Deck .. £92.86
4 Bands covering 560 kc/e-30 me/e I T Y Soft vinyl
Deluxe teak TUNER. coveredhead CARTRIDGE (P. & P. 50p)
FET, S Meter. Variable BFO for
SSE. Built-in Speaker, Band - veneered finish.
Size 145" x 9"
SIZE
ONLY
cushion and
earphones.
CR81 Deck with amps.
CR81D Deck
£6640
£5380
spread, Sensitivity Control. 220/
.

x 75". 8 ohms. 6 x 4 x 21in. 3 I.F. stages. Each ear- CR81T Recorder/Receiver £9275
240 v. A.C. or 12 v. D.C. 12fin. x CR8OSS 4 channel Recdr. £11425
41 in. x 7in. Brand new with att RMS.
watt Double tuned discriminator. Ample piece Incor-
16 watt peak. Complete with DIN output to feed most amplifiers. porates two CR8ODSS 4 channel Reed r. £93.65
Instructions. lead.
Our £25.00 Carr. Operates on 9V battery. Coverage
88-108Me/e. Ready built ready for
2" speaker unite. Fitted 2/4 hannel
changeover switch. Impedance 4-16
TAPE (P. & P. 75p)
4000D8 Deck .. .. £5995
Price 37p Our 2.95 Carr. use. Fantastic value for money. ohm. Frequency response 20-20,000 4000DS Dust Cover .. £3 95
Price L
£ L 7 1
50p Ha. Complete with 15 ft. coiled lead 1721L Recorder .. £6035
SKYWOOD CX203 Our
£5.95 P. p fitted two stereo plugs. X5000 Recorder
X201D Deck ..
.. £8250
.. £10820
RECEIVER ce Our P. P. .. £12895
HA-I0 STEREO HEADPHONE Stereo multiplex adaptors £4.97. Price L9.95 30p
GX220D Deck
0X22113 . .. .. £138 40
GX28OD Deck .. .. £19850
AMPLIFIER 0X370 Deck .. .. £21150
All silicon TAPE/CASSETTE (P. 8 P. 75p)
transistor GX1900D Deck .. .. 11144.80
IA©A®A©®a amplifier op-
eratee from
SH628 STEREO HEADPHONES L ROTELBA TAPE/CARTRIDGE (P. & P. 75py)
X1810D Deck .. .. £188.40
Solid state, 6 bands covering 200-
magnetic, Outstanding TAPE/CASSETTE/CARTRIDGE
ceramic or
ear -pads, RH700
420 HE. and .55 to 30 MHz. value. Soft (P. a P. 75p)
tuner inputs with twin stereo
Illuminated elide rule dial. Band - headphone outputs and separate adjustable X 20008D Recorder .. 118676
spread. Aerial tuning. BFO, AVC,
ANL, "S" meter, AM/CW/SS B.
volume controls for each channel. headband. STEREO MICROPHONES (P. 8 P. 50P)
Operates from 9v battery. Inputs 8.16 ohms. ADM.11 Dynamic (pair) £760
Integrated speaker and phone 5MÚ/100M1J. Output 50MW. 20.20,000 PHONES
socket. 220/240 V. A.C. r 12 v. STEREO RECEIVERS (P. & P. 75p)
Hz. Com- AA6300 20+20 watt .. £61.96
D.C. Size 325 x 266 x 160 mm.
Complete with instructions and Our 15.97 P. á P. plete with and stereo plug.
Soft leather
ear cushions. AA8030 26+26 watt .. £92.50
circuit. Price L 7 15p Impedance AA8080 40+40 watt .. £11760
Our Our P. 8-16 ohms. 20- AA810082 x 36 or 4 x 18w. £17600
e (32.50 Carr.
50p Price L 1'87 30p 20,000 Ha. 15ft AA8500 85+65 watt .. £150.50
coiled lead. STEREO AMPLIFIERS
1021 STEREO LISTENING Brand new and (P. 8 P. 50p)
LAFAYETTE HA -600 boxed (List AA5200 20+20 watt .. 561.75
STATION £9 95.)
RECEIVER AA5500 90+90 watt .. £78.60
For bal- AA0800 45+45 watt .. £117.50
ancing TE1018 DE -LUXE MONO HIGH P. á P.
and gain IMPEDANCE HEADSET Price £6'75 30p
STEREO TUNERS (P. 8 P. 50p)
AT550 AM/FM .. .. 68960
selection AT580 AM/FM .. .. 69460
of loud- Sensitive
epeakers magnetic 4-CHANNEL UNIT (P. a P. 50p)
with addi- headset with 881 Synthesiser .. .. 68995
General coverage 150-400 kc/e, 650 facility for etereo headphone
tional soft earpads,
Impedance SPEAKERS
kc/s-30 me/s, FET front end, 2 2,600 ohms 0888 (pair) £1020
switching. 2 gain control., speaker SW155 (each) £5100
mech. filters, product detector, on -off elide switch, stereo head- (d.e. 600
variable B.F.O., noiee limiter, phone sockets. 8" x 4" x 25". ohms). Fre- STEREO HEADPHONES
S Meter Bandspread. RF Gain. quency r '_00-4,000 Hz. ASE11 14.75
15in. x Olin. x 811n. 18 lb. Our P. & P. A8E20 5760
220/240 v. A.C. or 12 v. D.C.
Brand new with instructions. Price £2.25 Our
£ 1.97
ASE22 5995
Our £50.00 Carr. Price P
óp STEREO AMPLIFIERS
Price 50p RA310 15 + 15 watt £34.95 SPECIAL PURCHASE!
MP7 MIXER PREAMPLIFIER RA610 32 + 32 watt £5195
TRIO 9R59DS RECEIVER RA801 40 + 40 watt £79.95 FERGUSON EXPORT MODELS
5 micro- LHO2S STEREO HEADPHONES
RA1210 60 + 60 watt £8995
phone inputs P. & P. 50p extra.
each with Lightweight
individual headphones AM/FM STEREO RECEIVERS
gain con- RX160 75 + 75 watt £3896
with padded RX200 10 +. 10 watt £48'60
trols enabl- earpieces.
ing completemixing facilities. 4-10 ohms.
RX400 20 + 20 watt 85750 FERGUSON 3408 STEREO
Battery operated. 95" x 5" x 3". 20-20,000 P. & P. 75p. TUNER AMPLIFIER
Inputs Mice: 9 x 3mV 50K; 2 x Re. Com- Covers FM 88-108 MHz. Five push
4 bande covering 550 kc/s to 30 3mV 600 ohm. Phono meg. 4mV button tuning scales. 8+8 watts
me/e continuous and electrical 50K. Phono ceramic 100mV 1 meg. plete with rms. Input. for stereo ceramic
bandspread on 10, 15, 20, 40 and 8 II. cord and plug.
Output 2600mVV 100K. cartridge and tape etc. Separate
80 metres. 8 valve pine 7 diode bass treble, balance and volume
circuit. 4/8 ohm output and phone Our P. P. Our P.&P, UNREPEATABLE OEEER! controls.
lack. SSB-CW, ANL, Variable
BFO. S meter. Sep. bandepread Price £8.97 20p Price £1.95 30p P.
dial. IF frequency 445 kc/e, audio
output 1.5w. Variable RF and AF
Our
Price ,£31.50 5p
gain controls 115/250 v. A.C.
Size: 71n. x 191n. x loin. with HAND HELD 2-WAY WALKIE
inetruction manual. BH,00I HEAD SET AND BOOM
TALKIES
Our MICROPHONE
ce £49.50 Paid. Industrial quality in robuet metal
cases. Battery operation. Volume Movingeoll.Ideal
NIKKO TRM50
PULL RANGE OF TRIO STOCKED and squelch controls. Call button for language
and prese to talk button. Tele- teaching, com- STEREO AMPLIFIER
munications. FERGUSON 3418 STEREO

`2ái
scopic aerial. Complete carrying
Headphone Imp.
16 ohms. Micro-
17+17 watts rms. Inputs for mag-
netic and crystal phono, tuner,
TAPE DECK
4 track. 71 35, 15 i.p.s. Stereo/

OWE
channel Pair. phone imp. 200 tape etc. Dual stereo speaker out- mono record/play. 7" reels. Inputs
300mW Poet 50p. ohms. puts. Headphone socket. Full range for dynamic mikes, radio, gram.
3 channel
2 watt
9.50Poet 50p.
of controle. (Rec. List Price £59.50 Complete with cover.

£41.95 P.75 p
ALSO SEE Our P. P. & P. Our
PREVIOUS PAGES
Licence required loe operation in
U.E. Price £4.95 P 3 Our
Price £39.95 50p P
202
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/ J o I,o n c RECORD DECKS
III III Itl 111 I (H EOUIPMENTTy

ACP -8 8 TRACK ACR 3500

Carriage and Peeking 76p. Carriage and Peeking 600
CAR PLAYER CAR RADIO
Complete units with Stereo cart- H.8.ß. McDONALD Attractive black and silver finish. Manna m g o s :., um an AM/FM4+4 watt stereo tuner
ridge ready wired in plinth cover. 0114 Mint 19v neg. earth. Slider controls for Long waves. 12v pos. or neg. amplifier, Garrard 2025 T/C,
C129 Mono .. .. £5 50 Volume, Tone and Balance. earth. Complete with speaker, plinth and cover, stereo cartridge
GARRARD 0187 .. .. 1700 Channel selector button with red mounting brackete and instruc- pair of matching speakers.
2026 TC/9TAHCD .. £10.86 610/TPD1 .. .. £13 05 lamp. Complete with tion,.
BP25 111/0800 .. .. 615-95 810 speakers,pilot mounting brackets Our
SP25 111/M44E ..
ßP26 111/M44-7
.. £1845
.. £18-10
810/TPD1
710
.. .. 614 85 instruction'. Our
Price £6.50 P
50P
Price £30.50 £í0P0
SP25 111/M55E .. .. £18-90 810 .. 62400
ONLY £I2.507011;
SP25 111 Module/M75-6 £1899 710/810 Plinth and Cover 18 36
AP78/0800 .. 623.95
AP78/0800E .. .. £25-95 MP80/G800 .. 610 26 ACA SSE ELECTRIC ALBANY HOUSE
AP76/M44E MP60/TPD1 .. £12 80
AP78/M66E .. .. 125-85 MPOO/TPD2 .. £11 25 AM 108 SYSTEM
AP78/M75ED .. £31.70 CAR AERIAL
AP78/M76EJ .. £27.85 HT70/0800 .. .. £1880
API8 Module M75-8 .. 628.95 RTIO/TPD1 .. .. £15 95
AP96 Module M75-6 .. £90.40
ZERO 1008 Module/M93E £4185 CONa0I8881R
BD1 Kit ..
. .. £885 ACR1 PUSH BUTTON
H.B.ß. MeDONALD BD1 Chassie £10 75 5 section. Folly
2101807M £8.86 BD1/BAU2/Plinth/Cover £28 16 automatic. 12v DC.
MP60/0800
MP80/TPD1/0800
.. £1650
.. £16£0
BD2/BAU2/Chassie
BD2/SAU2/Plinth/Cover
£2270
£2876
CAR RADIO' Extends to approx.
40". Complete with
MP80/M44-7 .. £1880 Push button tuning of one LW switch, all leads and
HT70/TPD1/G800 .. £1880 GARRARDC and live MW stations of your instruction..
22 /Stereo .. £8 40 choice. 12v pos. or neg. earth. Our Price
°OLDHI80 SP25 III .. 8860
0L72/0800 .. .. £8090 SP25 III Acon 0P104 Complete with speaker, mounting
.. brackets and instructions. 8+8 watt amplifier, Garrard SP25,
0L71/0800
0L76/6800E ..
..
..
933 80
938'75
Ceramic
8P25/M75-6
..
..
£850
11690 Our P £5.95 plinth and cover, 6800 cartridge,
000DMAN8 AP78
SL66B
..
..
..
..
£1640
11135 Price £8.95 50p P & P 50p
pair of Medway T138 speakers.
TD100/0800 Teak .. £48.85 Our
TD100/0800 White .. £48.80 SL72B
SL96B
..
..
..
..
..
..
117.75
62529 AUDIOTRONIC DOLBY 'B' e £52.75 £i`25
LEAH 401 .. .. 62860 NOICE REDUCTION UNITS
Delta/M76-8 .. .. £4895 ZERO 106w .. .. £8030
PHILIPS ZERO 1008 .. .. £2795 Reduce tape hiss by 3dB at 80011a,
0A106/0P200 .. £18.80 8dB at 1200Hz and 10bB for all
0A160/0P200 Teak COLORING frequencies above 3000He.

ÏAT
.. £45.25 099 £1885 Size 18f" x 8" x 35x. AC 200/250v.
GA212/GP400 GIO1P/C .. 61885
0A908 (lees cartridge) .. £23 96 GLOM
..
.. .. £1675 PROCESS TWO
0A308 P.U. .. .. £3276 GL72 .. .. 117.86 For use with cassette and tape PROMS POOR
PIONEER 0L72/P . recorders. Freq. res. 30Hz-20%Ha For use with seml-profeasio tape
PL1ID (Leas cartridge) £29 Plinth 69/72 * 2dB. OE tape monitoring. recorders. Freq. res. 30Hx-20101a
* 2dB. S/N better than 70dB. All prices are subject to
PL16C (Lees cartridge) £4125 LID 72 .. 1270 Switchabie multiplex filter. Two
PL41D (Leas cartridge) £9585 GL76 12675 Dolby calibration meters. S/N Full source tape monitoring. (10p in
PL50 (Less cartridge)
PL61 .. ..
68990
.. 610276
6L78P
Plinth 75
LID 76
.. 629.30 better than 70dB.
Supplied with test cassette or tape
as required.
Record/Replay metering. Switch
able multiplex filter. Supplied with
test tape.
10°I0 VAT the f)
PLA86 .. .. .. £88 80 . Order with confidence by
0L86P/C .. 149-50 Our P á P Our P post - but remember to add
TROREN8
TD16OC/Ortofon M15E THOHEN8 Price £34.50 50p Price £50.00 50p
l0`ó VAT (10p in the f) to
total value of goods
Super .. . 682.50 TD128 II 66816 including carriage/packing
TD125 AB/11/Ortof on TD126AB II 678-66
M18E Super .. .. £9895 LOW NOISE TAPE CASSETTES and send cash with order.
TRIO 1680 PLEASE PRINT NAME 6
TD160A/II 62925 Top Hi-Fi quality In library cases ADDRESS CLEARLY.
WHARFEDALE TD180C .. 14895 TYPE 5 10 25 Cassette
Linton/M44-7 .. .. £.2870 060 1189 £2.68 £6 99 Tape Read
PLINTHS AND COVERS 090 11-85 18.62- £8.59 Cleaner Bop
Carriage and Peeking 60p 0120 6229 1448 11062
Budget BP28 etc. .. 12.06 P. 2 P. 16D. post free
Budget 401/arm .. £11.36
Budget AP78/Zero 1005 £3.95
Budget B.8.R. ..
Garrard WB1 .. .. £280 SEND LARGE S.A.E. FOR FULL HI-FI DISCOUNT LIST
Garrard SPC1 .. .. 1280
Garrard WB4
Garrard SPC4
SME2000 System
.. 12.66
.. £28.40 G.w.sM1TH EcocRAmo)lLto
ALL MAIL ORDERS TO:
SPECIAL GARRARD
11-12, PADDINGTON GREEN, LONDON W2 1LG. Tel: 01-262 6562
OFFERS! PERSONAL CALLERS WELCOME AT ANY OF OUR RETAIL BRANCHES
2 x 230 Stereo 60/P/Z5 610.95.
P. & P. 37p. CENTRAL LONDON 311. Edgware Road. W.2. Tel 01-2620387
2 x Z30/Stereo 80/PZ8 £18-00. STEREO 257 8. Tottenham Court Rd. W.1
10. Tottenham Court Rd. W.1
Tel 01-5800670
Tel 01-6372232
382. Edgware Road. W.2.
152!3. Fleet Street. E.C.4.
Tel
Tel
01-7234194
01-3532833
P. 2 P. 37p. .

2 x 250/Stereo 60/PZ8 £2025.

P. & P. 37p.
1025T 27. Tottenham Court Rd. W 1.
87. Tottenham Court Rd. W.1
Tel 01-6363715
Tel: 01-5803739
378. Harrow Road. W.9.
ESSEX
Tel 01 2869530

4 speed autochanger unit fitted 21. Old Compton Street. W 1. Tel: 01-4379369 86. South Street. Rom/ord. Tel Romford 20218
Transformer for PZ8 68.65. with stereo ceramic cartridge. 3. Lisle Street. W.0 2 Tel: 01-4378204 SURREY
Active Filter Unit 64-46. Our Carr. 34. Lisle Street. W.C.2. Tel 01-4379155 1046. Whitgitt Centre. Croydon. Tel.01-681 3027
Pair of Q16 Speakers 61070 Price £4.95 50p
118. Edgware Road. W.2.
193. Edgware Road. W 2
Tel: 01-7239789
Tel 01-7236211
27 S 21. Eden Street. Kingston.
32. Hill Street. Richmond.
Tel 01 5467845
Tel. 01.9481441
Project 60 FM Tuner 11496
Sinclair Project 606 620-97.
P. d P. 37p.
SP25III
WITH ACOS
ALL BRANCHES OPEN 9 a.m.-6 p.m. MONDAY TO SATURDAY
ALL EQUIPMENT IS All items and prices
All other Sinclair Products in stock GP104 BRAND NEW, FULLY are correct et
2000 Amplifier £9295 22-5-73
GUARANTEED AND
3000 Amplifier £28 8P85 1111.11. 4 speed sinle record but subject to
player fitted with Acos 0P104 CREDIT TERMS FOR OFFERED WITH FULL
9000/3000 Tuner £2880 etereo ceramic cartirdge. change without
CALLERS (£50 and over)
Q830 Speakers 62898 pair Our £8.50 Carr.
AFTER SALES SERVICE notice. E 6 0. E.
P. P. 50p each of above items Price 50p

203

www.americanradiohistory.com
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EF98 .8 KTW82 .8 P1.608 .90 1726 .66 81 B7168 88 0A200 10
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ORP12

.84 12.4178 .21 90PL14 .76 DY87/6 .22 EC82 .28 HL42DD.8
PFL200 .60 U789 .27 AC126 18 LP16 (AC113. AC164. AC167. AA120) 4683
OARS 80 6776
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81-0044 A 2-0046, 47p. 1-0082D. &
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6AV8 .88 61170 .18 12BE6 .80 36D6 70 E87 1.8 EC88 54
8AW8A .64 61180 .8 12BH7 .27 36L6GT .42 E89F 1.20 501.86 .88 All goods
are unarmed, boxed, and subject to the etandard 90 day guarantee. Terms of bmineee-
BAX4 .89 OLI .98 12J7GT .8 35W4 .88 E8800 .8 EF22 .68 Cash or cheque with order only. Despatch charge 9p per order up to three Items, then each additional
8B8G .18 88GT .50 12118 .60 38Z4GT .N 59200 .40 EF40 .49 item 8p extra. Orders over 8600 poet/packing free. flame day despatch by first clam mall. Any
6BA8
8BC8
8BE6
.19 8L7
.50 6L18 .44 12Q7GT
.20 8119 1.88 12807
8
.88 121176T .84 38Z60T .80 51807 .90 EF41
6006
.85 600D60
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51148 .68 EF73
.58 parcel insured against damage in transit for only 3p extra per order. Terme of business free on request.
.38 Buslneee hours Mon. -Fri. 9-6.80 p.m.
76 We do not handle seconde nor reject-, which are often described as "New and Tested" but have a
6BH6 .43 6LD20 .48 12807 .8 817 BASO .27 EF80 .2111m1ted and unreliable life. No enqulrlea answered unless S.A.E. le enclosed for reply.

4-STATION INTERCOM
r RECHARGEABLE

0
U.H.F. T.V. AERIALS
SUITABLE FOR COI.OUR AND MONO- Mallory Cells in U2, U11 and
CHROME
RECEPTION
All U.H.F. aeri-
Penlite U7 sizes,
als now fitted
with tilting brac- KESTREL BATTERY
CHARGING UNIT ..
ket and 4 ele-
ment reflector. .
£7.99 LOFT MOUNTING ARRAYS
7 element 2.25. 11 element 2.75.
ti,lve your communics-
Lion problems with thl. 14 element 3.25. 18 element 3.75
4 -Station Translator Intercom system (1
8 Subs), in de -luxe plutie cabinets for deck
muter and WALL MOUNTING cw
or wall WALL ARM & BRACKET
mounting. Call/talk/listen from Master to Subs and 7 tlentent 3.25. I1 element 3.75. 14 element
Subs to Master. Ideally suitable for Business, Sur- 4.25. 18 element 4.75. CHIMNEY MOUNT-
gery, school., Hospital. Office and Home. Operates
on one (IV battery. On/off switch. Volume control.
ING ARRAYS cw MAST & LASHING
Complete with 3 connecting wires each 86ft. and KIT. 7 element 4.00. 11 element 4.50.
other accessories. P. A P. 44p 14 element 4.75. 18 element 5.25. MAST
MOUNTING arrays only. 7 element 2.25.
MAINS INTERCOM NEW MODEL 11 element 2.75. 14 element 3.25. 18 ele-
No batt ries -eso wire.. Just plug in the main. ment 3.75. Complete assembly instructions Use for
for Instant two-way, loud and clear communication. with every aerial. LOW LOSS coaxial cable
On off ewitch and volume control. Price 81696 9np yd. KING TELEBOOSTERSfrom 3.75. Tape recorders, Portable radio and TV.
P. h rh LABGEAR PRE -AMPS 4.25. Radio controlled model aircraft and
BELLING LEE CONCORD BOOSTER boats, Cine cameras, Flashguns, Cord-
V.H.F., F.M., U.H.F., mains operated 8.20. less shavers and other battery appli-
State clearly channel number required on all ances.
orders. P. p. on all aerials 50np. Accs. 1Snp.
OUR C.W.O. Min. C.O.D. charge 25np. Whenever you must have PRICES
PRICE utterly dependable battery Batteries U2
ONLY equiv. £1 52

Same a. 4.01a re.ont tor two-way instant

F.M. Radio Aerials power-then these
Alkaline -Manganese
new
re-
tax paid
Penlite U
communication. Ideal as Baby Alarm and Door F.M. RADIO loft S/D 1.00 3 element 3.25. chargeable cells will provide equiv. SSp
Phone. Complete with 66ft. connecting wire. 4 element 3.50. Standard coaxial plugs 9np. tax paid
Complete with Battery. P. R P. 2911 Coaxial cable Slip yd. Outlet box 30np. it. Thecells can be recharged
Uif equiv.
P.p. all aerials Soap. Accs. 30np. C.W.O. many times, a simple Job £1 13 tax paid
Min. C.O.D. charge 25np. Send Sop for fully with the Kestrel Charging
illustrated lists. Charging
Unit which has been speci- unit £779 tax
£3.41 ally designed for these new paid with one
CALLERS WELCOMED battery
Why not boost type batteries. holder
bullies/ effi- OPEN ALL DAY SATURDAY
ciency with thu iocredible Deluxe Telephone AmoS- ALL PRICES INCLUDE V.A.T.
tier. Take down long telephone messages or converse
without holding the handset. A useful otnce aid. On/
off switch. Volume Control. Complete with Battery.
K.V.A. ELECTRONICS Send to:
P. d P. 24p. Full price refunded It not sanded in 40-41 MONARCH PARADE, LONDON 275WEST END LANE
7 days.
ROAD, MITCHAM, SURREY LONDON, N.W.8 1QS
WEST LONDON DIRECT SUPPLIES IPW.61 01-794 9611
169 KENSINGTON HIGH STREET, LONDON, W.8. Telephone 01.648 4884 &,tsh &Meksitot

204

www.americanradiohistory.com
 The X25
Why two
shafts?
220-240 Volts or 100-120 Volts.
Model X25
The leakage current of the
X25 is only a few

'elementary"
microamps and cannot harm
the most delicate equipment
even when soldered"live
Tested at 1500v A.C.
25 watt.Fitted long -life
iron-coated bit 1/8"
y
One ceramic shaft to give you near -perfect insulation and negligible
2 other bits
available 3/32" leakage current (only 3-5 microamps) so that you can safely solder
and 3/16" delicate and expensive integrated circuits and transistors, even when "live"
Price: £1.75 Another shaft, of stainless steel, to give you the strength required
(rec. retail)
P & P 89
of an everyday robust general purpose iron.
Plus large volume long -life bits to store the enormous heat-capacity
of the 25 watt element. Bits that do not stick (no screws or pins)
and bits that slide over the element shaft to give you efficient heat
transfer and a capacity equivalent to irons of 2-3 times the wattage.

MODEL G
MODEL CCN 18 watt miniature iron, fitted with MODEL CN
220 volts or 240 volts. The 15 watt long life iron -coated bit 3/32" Miniature 15 watt soldering iron fitted
miniature model CCN also has Voltages 240. 220 or 110. 3/32" iron -coated bit. Many other bits
PRICE: £1.95 (rec. retail). P&P 5p available from 3/64", to 3/16".
negligible leakage. Voltages 240, 220. 110. 50 or 24.
Test voltage 400v. A.C. Totally
PRICE £1.75 (rec. retail). PáP Sp
:
enclosed element in ceramic shaft.
Fitted long -life iron -coated bit 3/32". MODEL CN2
4 other bits available 1/8", 3/16", 1/4" All prices mentioned Miniature 15 watt soldering iron fitted
and 3/64". are exclusive of V.AT. with nickel plated bit 3/32".
Voltages 240 or 220.
PRICE: £195. P&P 5p
PRICE: £1.75 (rec. retail). P&P 5p
MODEL SK.2 KIT

-.--
..r
"T
MODEL
MES.KIT
Battery -operated 12v.
25 watt iron fitted
e
MODEL
Contains 15 watt miniature
iron fitted with 3/1
bit, 2 spare
bits 5/32"
and 3/32"
with 15' lead and 2
SK.1 KIT heat sink,
heavy clips for con- Contains 15 watt solder,
nection to car battery. miniature iron fitted with 3/16" and "How to
Packed in strong bit, 2 spare bits 5/32" and Solder"
plastic wallet with book- 3/32", heat sink, solder, stand booklet.
let "How to Solder" and "How to Solder" booklet. PRICE:$2ee
PRICE: £2.OS (rec. retail). PRICE: £295 (rec. retail). Irec. retail).
P&P 12p P&P 12p P&P8P

ElPlease sendthe ANTEX enclose cheque/P.O./Cash

00000
I

colour catalogue. (Giro No. 2581000) Reg. No: 393594

Please send the following:
From radio or electrical dealers,
car accessory shops or
NAME
in case of difficulty direct from:-
ADDRESS
ANTEX LTD. FREEPOST
(no stamp required) PLYMOUTH PW7
PLI 1BR. Tel: 0752 67377.

205
 parts for for fast,easv
reliable soldering
Ersin Multicore Solder contains 5 cores
of non -corrosive flux, instantly cleaning

PRACTICAL heavily oxidised surfaces. No extra flux

is required.

EASY-TO -USE IDEAL FOR HOME

WIRELESS DISPENSERS CONSTRUCTORS
Size 1 cartons in 40/60, 60/40
Size 5

projects Savbit alloy

18 swg, 18p
(illustrated).
Size 19A
and Savbit alloys
in 7 gauges 25p

mow
After many requests, Electro Spares are now supplying lists of
components for ALL the projects featured in "Practical Wire- 60/40 alloy Size 12
less", commencing this month. Just forward an S.A.E. (Pre- 18 swg, 18p for Service
ferably 9" x 4" minimum) stating which project is of interest to Size 15 Engineers and
you-we will forward an individually priced list of components 60/40 alloy Electricians. .
required. No need to buy a full kit-you need only purchase the 22 swg, 22p 75ft of 18 swg

fg
parts you require at any one time.
All Electro Spares supplied components are new, branded products Savbit alloy. 75p eztjel
of reputable manufacturers and carry full makers guarantee.
We regret we cannot supply lists for projects published before
this issue. BIB WIRE STRIPPER AND CUTTER,
"ONE SOURCE" BUYING MAKES SENSE-IT CAN SAVE Deluxe Model 9 Automatic opening spring,
YOU TIME, MONEY AND POSTAGE. locking catch, plastic -covered handles. Case
hardened and precision ground. Adjusts
to most wire sizes. Cuts and strips
"p.e." f.m. varicap stereo tuner flex, splits plastic twin flex. 75pJ
Electro Spares offer a kit of high quality parts to the published
specification for this remarkable tuner, featured in "Practical Prices shown are recommended retail, excluding VAT.
From Electrical and Hardware Shops. If unobtainable, send lop p&p direct to:
Electronics" May 1973. Multicore Solders Ltd.. Hemel Hempstead, Hertfordshire HP2 7EP
Features include push button "Spot On" tuning, with up to
5 pre-set stations (no difficult tuning dial and drive cord). Easy
"no problem" construction, requiring only a few simple setting
up adjustments with a D.C. Voltmeter. Uses NEW pre-set
modules for R.F. and I.F. Circuits-no circuit alignment. High (;HAHNEL STEREO
efficiency Integrated Circuit Phase Lock Loop Decoder for
perfect stereo reception, with stereo lamp indicator. Fibre Glass
P.C. Board, neat slimline cabinet with brushed aluminium front
Lrsju, ,,:
:::: CONVERTER
panel, push buttons etc. etc. TRANSFORMS
Create a new
IDEAL FOR USE WITH THE "TEXAN," "GEMINI" AND
ANY GOOD QUALITY STEREO AMPLIFIER sound
that
-
dimension in
sound
engulfs
YOUR STEREO
SYSTEM INTO
SENSATIONAL
Please send large S.A.E. for full details. you with nat- QUADRAPHONIC
SOUND
ural realism
from every INTRODUCTION
"p.e. gemini" stereo amplifier corner of your
room. Simply wired to your amplifier or Tuner/Amp.
speaker outputs and again into 4 speakers. Neat inc. carr. V.A.T.
65
QUALITY HI-FI FOR THE HOME CONSTRUCTOR styling with brushed effect console panel. Peak input power 50w into
8 ohms. Front Hi/Low Level 6dB. Phone jacks for input and output.
30 Watts per channel into 8 ohms! Total Harmonic Distortion Size: 6"x 34"d. x 2"h. Guaranteed. Callers welcomed for demonstration.
0.02%l Frequency Response (-3 dB) 20Hz-100kHz!
We are still continuing to supply components for this fabulous (Dept. PW
S), 43 BARTHOLOMEW CLOSE,
Amplifier, which is now recognised as practically the ultimate LONDON, ECIA 7HP. Tel. 01-600 3211.
in High Fidelity. We know of no better unit for the Home Con-
structor-we can supply a Booklet containing full specification,
complete constructional information wiring diagrams, fault
finding guide, etc. etc. Price 55p, plus 4p postage.
Our New Low Price List is supplied with each booklet, or
supplied separately on receipt of a large S.A.E.
FOR PEOPLE WHO REQUIRE THE BEST, IT HAS TO
poly -planar
BE THE 20-Watt
Full Range Speaker
"p.e. gemini". Completely replaces the
conventional cone speaker
Note Our New Address-With New Mail Order Department Super -thin construction
For Quick, Efficient Service. permits new installation ideas.
PLEASE PAY US A CALL-VISITORS WELCOME. Power capability: 40 watts peak. Frequency range: 40 Hz -20 KHz
NO PARKING PROBLEMS Sensitivity: 85 dB/M for 1 watt electrical input. Input impedance:
8 ohms. Operating temperature range: -20°F to ±175°F. Size
(WnDzL): 17/16"x411.3/4"n 14.11/16". Weight: 19 ounces.

Electro -Spares £7-50 each Stereo pair £1450

post free
ECCLESALL ROAD,
288,
SHEFFIELD, SII 8PE web europa
"THE COMPONENT CENTRE OF THE NORTH" P.O. Box 162, Watford WD1 1AA

206

www.americanradiohistory.com
 YOUR COMPLETE AUDIO -ELECTRONIC STORES
More of everything at the right price. All your electronic requirements
within 200 yards - call and see for yourself.

INTEGRATED CIRCUITS SPECIAL OFFERS! PLESSEY INTEGRATED CIRCUIT

8 Watt Amplifier SL408D
SEMI -CONDUCTORS Complete with 8 -page
Why buy alternatives when you can buy the genuine article from us at BFY90 59p 2N2926 10p booklet, circuite
competitive prices from stock. BRANDED FROM TEXAS I.T.T FAIR- 1000 MC/S All Colours and data
CHILD
25 + 50p
100+ 45p
25 + 9p
100 + 8p
f1.50 each
500 + 40p 500 + 6p
1000 + Sp TRIACS
STUD WITH ACCESSORIES !j¡
Type 1/1112/24 25/99 Type 1/11 12/24 25/99 Type 1/11 12/24 26/99 AFI I7 Mullard 25p 2N3819 Texas 35p Type Volte Price
p p p 25 + 17p 25 + 30p P.I.V. 1-11
667400 0.20 0;16 0.16 7367460 8674145 1.60 1.40 1.80
0.20 0.18 0.16 100+ 13p 100 + 25p 8 AMP RANGE
0N7401 0.20 0.18 0.18 867461
0.18 0.16 8674150 8.86 2.95 2.15
0.20 500 + 12p 500 + 20p SC86A 100 75p
867463
0.18 0.16 9674151 1.10 0.95 0.90 100 + 15p OMB 200 79p 1 H
867402 0.20 0.18 0.16 0.20 0035D 400
867403 0.20 0.18 0.16 0.18 0.16 82174163 1.85 1.27 1.20
867454 0.20 85p
SN7404 0.20 0.18 0.18
0N7460 0.18 0.16 0674154 2.00 1.75 1.55
0.20 0C170 Mullard 25p BC107, BCI08, 6 AMP RANGE (T048)
100 e
867406 0-20 0.18 0.16
067470 0.27 0.26 13674105 1.55 1.47 185
0-80 25 + 20p BCI09 10p each SC4OA 862
667406 O.80 0.27 867472
0.26 0.27 0.26 8674166 1.55 1.47 1.85
0.80 100 + 18p All Makes SC40B 200 90p 3 Amp
967407 0.80 0.27 0.25
867473 0.87 0.85 8674157 1.80 1.70 160
0.40 8C40D 400 1100
500 + Isp 25 + ep 8040E 600 11.20 T048
8107408 0.20 0.19 0.18
867474 0.27 0-85 8674160 6.60 2.40 2.25
0.40 1000 + Ilp 10 + 7p
867409 0.46 0.48 0.85
867475 0.52 0.60 6674161 2.60 2.40 2.25
0.66 10 AMP RANGE (T048)
0.42 0.89 87674162 8.40 8-25 2 70
500 + 6p 8C46A 100 959
867410 0.20 0-18 0.16
067476 0.45 1000 + 5p
167411 0.88 0.22 0.20
8217480 O. SO 0.76 0.67 87674183 8.40 5.26 2.70 9C46B 200 5100
8207412 0.42 0.40 0.86
867481 1.26 1.16 1.10 8674184 2.75 2.80 2.10 BYI27Mullard ISp SC45D 400 11.25
8227413 0.80 0.27 0.26
BN7482 0.87 0.80 0.70 8674186 4.0 8.50 8.0 25 + 12p ADI6I, AD162 35p 8046E 500 11.45
9817416 0.20 0-27 0.26
8N7483 1-00 0.90 0.86 8674180 4.0 8.50 8.00 100 + 10p each 16 AMP RANGE (T048)
867417 0.80 0.27 967484
0.25 0.90 0.85 0.80 81074107 8.25 6.60 5.10 500 + 9p 25 + 32p 6030A 100 11.25
067420 0.20 0.18 0.16
867480 0.46 0.41 0.88 82174170 4.10 865 8.05 100 + 8p 10 + 189 6000B 200 1185
067422 0.48 0.44 8N7490
0.40 0.75 0.70 0.65 8674174 2.00 1.75 1.80 500 + 2Sp BC60 400 51.85
867423 0.48 0 44 9N7491AN1.00 0-96 0.90
0.40 8674175 1.85 1.27 1.15 1000 + 220 73060EE 500 51.86
8677426 0.48 0.40 0.86
867492 0.75 0.70 0.86 82174176 1.60 1.85 1.20 0A202 10p DIAL D32 25D
967427 0 42 0.89 067498
0.86 0.76 0.70 0.66 9674177 1.60 185 1.20 25 + 8p 2N3053 20p TRIACS-
8217428 0 50 0 45 867494
0.42 0.80 0.75 0.70 82174180 1.55 1.80 1.20 10 + 7p 25 + I8p Addltlonal Types
867430 0.20 0 18 867496
0.16 0.80 0.76 0.70 8674181 7.0 6.0 6.50 500 + 6p 100 + 1Sp
40430 (T086) 86p 15 Amp
6N7432 0.42 0.59 0.85
0217496 1.00 0.97 0.96 73674182 2.0 1.80 1.60 100+Sp 500 + 12p 40669 (Plastic)
8N7433 0.70 0.61 867497
0.44 6.25 b-50 6.00 82174184 8.40 2.0 1.80 1000 + IOp 2100 T048
867487 0.65 0.60 0674100 2.50 2.80 2.0 62174185A 2.40 2.00 1.80
0.50 40486 (T05) 805
867438 0.65 0.80 5N74104 1.45 1.85 1.20
0.50 82174190 1-95 1.86 1.75 0C35 Mullard S0p
867440 0.20 0.18 02174106 1.45 1.85 1.20
0.16 9674191 1.95 1.86 1.76 25 + 4Sp
2N3055
25 + 509
55p NEW BRIDGE
6217441AN0.76 0.72 8674107 0.50 0.46 0.40
0.70 8674192 2.00 1.90 1.80 + 45p RECTIFIERS
B67442 0.76 0.76 8674110
0.70 0.80 0.70 0.60 81474193 2.0 1.90 1.80 100 + 405 100
0674118 1.0 0.96 0.90 9674194 8.60 2.26 1.90 500 + 335 500 + 38p SMALL SIZE AND LOW COST
067443 1.0 0.95 0.90
8674119 1.90 1.78 1.66 9674196 1.26 1.70 1.60 1000 + 305 100 + 22p Type Volte Price
8N7445 2.00 1.75 1.60
867448 8 00 1 76 1 60 9674121 0.60 0.55 0.60 11674196 1.50 1.40 1.80 P.I.V. 1-11
8674122 1.86 1.25 1.10 82174197 1.50 1.40 1.80 HALF AMP
6217447 1.75 1.60 1.45 6674123 2.70 2.56 2.47 62174198 4.60 8.70 8.85 B05/06
867448 1.75 1-60 1.45 8674141 1.0 0.95 0.90 8674199 4.60 8.70 8.85 ZENER LINEAR B05/10
50
100
209
85p
PRICES OF 7400 SERIES ARE CALCULATED ON THE TOTAL NUMBER
DIODES (0/P AMPS) ONE AMP h x I H
TUBULAR
ORDERED REGARDLESS OF MIX 400 M/W 5% 702C TOS 75p B105 50 26
LARGER QUANTITY PRICES PHONE (01) 402 4891 Miniature 7090 T099 869 B1/10 100 859
HIGH POWER SN 74 HOO 1 Now in stock-send BZY 88 Range 709C D.I.L. 360 9120 200
LOW POWER SM 74 LOO J for list No. 36 723C T099 11.0 B1/60 600 S0á99
All voltages 7230 D.I.L. 959 ONE AMP (0.I.)
3.3-33 Volt 7250 T09934-50 TUBULAR
10P each. 741C T099 55p W005 50 80p
A SELECTION OF SEMI -CONDUCTORS FROM STOCK 7410 D.I.L. 552
26+ 99 W01 100 869
AAY30 105 BC147 129 B17106 2.26 0C44 169 T1848 869 263065 655 109+ 89 7470 T099 1110 W02 200 409
AAY42 162 BC169C 12p BY100 114 0046 16D V405A 269 268440 75p 600+ 6.6p 747C D.I.L. WOO 600 469
1.4218 lOpBC182 105 BY128 169 0057 509 ZTR108189 2N34421.26 1000+ 52 1110 TWO AMPS 4H x IL
AC107 869 B0214 165 BY127 159 0071 169 ZTX300 129 268626 76p 72741P D.I.L. 809
AC128 252 BCY32 762 BY213 859 0072 269 ZTR301169 268e14 69p Any one type. 72748P D.I.L. BOp B2/09 60 ß6p
AC127 269 BCY34 869 0108D 665 0077 46p ZTR302180 268816 765 SINCLAIR B2/100 100 40p
AC128 265 BCY39 1-00 0ET111569 0081 26p ZTR841209 2N8702 10p 15 Watt 6% IC12 61 80 B2/20 200 45p
AC176 260 BCY42 80p GET116 559 0083 259 ZTR500 169 268704 lOp Wire Ende TOSHIBA 92/60 600 509
A0187 265 BCY43 25p GET880 459 00140 669 ZTR603 17p 263705 lOp Metal Case TH9o13P B2/1000 1000 60p
AC188 26p BCY66 2-60 LM30911 00170 269 20301 809 268714 1.80 All voltages 20 WATT AMP FOUR AMPS
ACY17 80p BCY70 169 (T03) 187 0C171 802 22404 809 2N87711-76 6.8-100 Volte /4.47 POST PAID ¡H xB44/1004L

ACY20 209 BCY71 209 MAT121865 00200 459 210627 862 268773 2-0 209 each TH9014P Pre Amp 100 60p
ACY21 899 BCY72 169 MJE840 605 00201 75p 220896 16p 263790 2.26 11.60 B4/200 200 85p
ACY39 665 BCY87 249 MJE370 70p 00202 805 26897 15p 268819 865 25+ 18p
DATA AND B4/400 400 700
AD140 600 BCZ11 602 MJE620 769 00203 60p 26708 30p 263820 509 100+ 189
CIRCUITS REF. B4/600 600 76p
AD149 602 BD124 80p MJE2966 OCP71 1-26 26930 20p 263888 869 600+ 129 42 102 B4/800 800 1100
AD181 869 BD131 769 110 ORP12 609 221987 45p 2218903 169 1000+ 10p BI AMPS
AD162 869 BD132 809 M2E3055 ORP80 409 261131 Up 268906 125 FREE WITH
BF116 261132 25p 264081 129 Any one type. PURCHASES x100
AF117 BOp 260 762 P848A 202 B6/100}L 709
AF118 605 BF167 269 3OPF105 402 RA8810AF 2211302 189 264082 12p B6/20 200 76p
AF124 259 BF173 959 NKT214209 469 2211304 22p 264128 165 3 Watt Plastic B6/400 400 90p
AF139 800 BF179 802 NKT210402 RA8608AF 261305 229 264871 865 Wire Ende 5% TRANSISTORS, B6/600 600 61.0
AF186 40p BF180 809 NKT217405 669 2201307 261) 2106457 305 SEE Range IC's, TRIACS,
AF289 40p BF194 165 NKT403709 TAA283760 261308 259 266777 665 SILICON CONTROLLED
46227 BF196 NKT40460p TIL209 89p 261813 20p 28001 1 00 All voltages BRIDGES, RECTIFIERS
805 162 8.8-100 Volts Volte
A8Y28 262 BF881 259 OAS 60 TIP29A 609 261871 1.0 26012 10-00 Type Price
BA102 802 BF098 0A10 862 TIP30A 609 2212147 76p 28018 6.26 809 each. SCR's, LDR's P.I.V. 1-11
265
BA116 7p BFX13 2611 0A81 109 TIPS1A 60p 262180 69 29026 8 90 ONE AMP
BA146 169 B21R34 769 0A91 7p TIP32A 709 262217 259 20301 605 CRS 1/06 60 215p
BAX13 bp BFX37 809 0A200 7p TIP38A 262221 209 28303 655 SILICON CBS 1/10 100 80p
BARE( 79 BFR88 805 0A202 109 1-0 2212222A 28324 95p RECTIFIERS CRS 1/20 80520
0016 TIP34A 26p 40260 WIRE ENDED CRS 1/40 400 85p
BC107 lOp BFY60 209 75p 500 PLASTIC 600 450
BC108 lOp BFY51 20p 0020 969 1.60 262389A 40360 40p CR131/80
BC109 100 BFY62 205 0023 869 TIP86A 169 40361 40p Type P.I.V.1.11 THREE AMP (T0481
0025 2212906 20p 40362 505 1 amp miniature
CRS 8/05 60 80p
BC3090 189 CRS 3/10 100 80p
BFY64 69p
BFY90 0028 6 6p TIP88A8.60 0212928 (all 40408 501) IN4001 50 6
BC118 162 BLY38 8.0 0035 501( 8-00 cole) lOp 40486 76p 164002 100 7 CRS 3/20 200 860 1 Amp
BC117 20p B8R20 165 0036 669 TIP41A 769 268063 20p 40688 1.10 IN403 200 8 CRS 3/40 400 45p
BC143 852 B9Y27 16p 0042 409 TIP42A 862 263064 609 40430 1.0 I10404 400 8 CRS 3/60 600 655 T05
I10405 600 10 FIVE AMP (T0136)
ii
IN4006 800 12 CRS 5/400 400 609
Prices DO NOT include QUANTITY DISCOUNTS I64007 1000 16 NEW FREE SEVEN AMP (T048)
V AT Value Added Tax. From 10% 12+ ; 15% 25+ ANY ONE 1.6 amp
P14001
miniature BOOKLET
CRS 7/100 100
CRS 7/200 200
609
85p
1st April, 1973 10% must be added 80% 10+; 26% 250+ TYPE
PL402
60 8
CRS 7/40 400 702
and shown separately to your total From above sections except Integrated
100 9 (No. 36) CRS 7/600 600 859
order (incl. carr/packing). Help
us to help you receive your order
without delay. E. & O. E.
Circuits and Special Offers where dis-
counts are included.
Minimum order valve al please.
PL403
PL404
P14006
PL4006
200
400
600
800
10
10
12
16
OVER
TYPES
Bend
-1500

for yours
SIXTEEN AMP
SCR 16/100 100
SCR 16/20 20
655
70p 3Amp
Postage 7p on all orders. PL4007 1000 16 today SCR 16/400 400 80p
I
0CR 10)000 000 !1 00 T048

Henrys LIMI IED

EDGWARE ROAD, W2
404.406 Electronic Components and Equipment 01-4028381
354-356 High Fidelity and Tape Equipment 01-4025854/4736
309 PA- Disco -Lighting High Power Sound 01-723 6963
303 Special offers and bargains store
Al/mail to 303 Edgware Road, London W2 113W
Open:- 9 am -6 pm
6 days a week
/309 closed
Thursday)
Al/ stores open
all day Saturday

207

www.americanradiohistory.com
 UNISOUND FOR THE NEW SOUND
AT It's the RT -VC system that screws together to save you pounds' Unisound
comprises two superb speakers and an amplifier/record deck plinth-all
£26.12 beautifully finished in simulated teak. The stereo amplifier (4 watts per channel
into 8 ohms) is based on the famous Mullard Unilex system brought up-to-date
INC. by RTVC using Integrated circuits. Turntable is the proven Garrard 2025TC
VAT complete with stereo cartridge and tinted acrylic cover. Speakers are big EMI
Twin -cone units all ready for mounting in their elegant cabinets, which simply
need screwing and glueing together. Easy step-by-step instructions. £26.12
complete plus £1 40 packing + 81.40 post. Diamond Stylus £1.37 extra.
Stereo headphones with adaptor £4.40 extra. Send for leaflet.

AN RTVC EXCLUSIVE DESIGN

UNISOUND MODULES ONLY £7.65 + 55p. p. & p.

For the man who wants to design his own
stereo-here's your chance to start, with
Unisound-pre-amp, power amplifier and
control panel. No soldering-just simply
screw together. 4 watts per channel into
8 ohms. Inputs: 12OmV (for ceramic
cartridge). The heart of Unisound is
high efficiency I.C. monolithic If you can solde)
power chips which ensure very on printed circuit board
low distortion over the
audio spectrum. you can build this push-buttor
car radio kit. It's simple-jus
follow the step-by-step instructions

THE TOURIST
PUSH BUTTON
CAR RADIO KIT

AN INCREDIBLE BUY
ONLY FROM R C
The Tourist PB is suitable for 12 volt working on both negative and positive earth * Circuit diagram and
vehicles. It covers the full medium and long wave bands. It is permeability tuned and comprehensive instructions
sturdily constructed. Output is a full 2 5 watts into an 8ohms speaker. But the Tourist 55p free with parts.
PB will operate into any loudspeaker from 8 to 15 ohms.
Apart from the output stage, which is an intergrated circuit, the only other electronic " Fully retractable & lockable car aerial £1-37
components that need soldering are some capacitors, resistors, etc. The kit includes post paid.
a pre -built RF tuner unit, and fully modulised IF stages which are pre -aligned before
despatch. As well as electronic components this kit also contains 2 diamond -spun CAR RADIO KIT £6.60 p. and p. 55p
aluminium knobs, elegant matching front panel, dial, washers, screws and wire. Speaker with baffle and fixing strips £1.65
The Tourist PB can be mounted in any standard size dash panel and it has an illumina- 27 p. & p., post free If bought with the kit
ted tuning scale. Chassis size is: 7" wide, 2" high and 4-f}" deep. Send S.A.E. for leaflet.

AN ELEGANT 20 WATTS MONO AMPLI-

RELIANT Mk IV FIER FOR ONLY £1350 (inc. VAT). IDEAL
FOR YOUR DISCO.
'5 Electrically Mixed inputs. '3 Individual Mixing controls. 'Separate bass and treble
controls common to all 5 inputs. *Mixer employing F.E.T. (Field Effect Transistors).
"Solid State Circuitry. *Attractive Styling INPUTS 1. Crystal Mic or Guitar 9mV. 2.
Moving coil Mic. or Guitar 8mV Inputs. 3, 4 & 5
are suitable for a wide range of medium output
equipment (Gram. Tuner, Monitor, Organ, etc.)
All 250mV sensitivity. Output 20 watts into
£13.5060p
P

8 ohms (suitable for 15 ohms). Size approx. 12# x 6 x 3# ins.

SOUND 50 45 WATT MONO AMPLIFIER. Ideal for

Disco Work. Output Power: 45 watts R.M.S. PE TAPE LINK
(Sine Wave) Frequency Response 3dB points 30Hz and 18KHz. Total CONSTRUCTORS
Distortion: less than 2% at rated output. Signal to Suitable 3 speed tape
noise ratio: better than 60dB. Bass Control Range: deck, less heads. Caters
13dB at 60Hz. Treble Control Range: 12dB at 10KHz. up to 7ins. spools. 240V
Inputs: 4 inputs at 5mV into 470K. Each pair of AC mains Un-lsAe00
inputs controlled by separate volume control. used but store
2 inputs at 200mV into 470K. Size:
191 x 104 x Sins. Amplifier £31 -35 plus £31 35 soiled hence
no warranty.
plus
£1 p. á p.
£1 -65 p. and p. (inc. VAT)

208

www.americanradiohistory.com
All prices include VAT

PRICES: SYSTEM I

Viscount R 102 amplifier

III £24 20 + LI p & p
2 Duo Type speakers
II £14 00 + £2 20 p & p
G d SP25 Mill with
MAG. cartridge plinth & cover £18 00 + £1 75 p & p
total £56 20

Available complete for only £49 +

£3-50 p. á p.
PRICES: SYSTEM 2
Vicount R 102 amplifier L24-20 + LI p & p
2 Duo Type Ill speakers L32-00 + 13-30 p & p
Garrard SP25 Mk. III with
MAG. cartridge plinth & cover L18-00 + L1-75 p & p

VISCOUNT III
total £74-20

Available complete for £65 +

£4 p. & p.

AUDIO SYSTEM £49

COMPLETE
20 - 20w. r.m.s. 40Hz to 40kHz ± 3dB. Total distortion at 10w. at 1kHz - 0.1%.
This is real value for money! We have designed 2 systems and the heart of
them both is the Viscount Ill amplifier. A unit of great eye appeal with teak
finished cabinet. FET's (Field effect, transistors) are incorporated on the input
stages, just like top priced units. FET's give you more of the signal you want
and almost none of the hiss you don't. Both units have output sockets for
headphones and tape recorder.
For both systems we have chosen the famous Garrard SP25 Mk. Ill deck,
with fitted magnetic cartridge, which comes complete with simulated teak
plinth and tinted acrylic cover.
The exclusive Duo loudspeaker systems are incomparable for quality within
their price range. Large speakers in extremely substan-ial cabinets. There's a
choice of the Duo II's for the smaller room or the big Duo
Ill's for real bass response.

SPEAKERS: Duo Type II Size approx. 17in. x 10}in. x 6fin. Drive unit 13in. x 8in. with parasitic
tweeter. Max. power 10 watts 8 ohms. Simulated Teak cabinet. £15.40 a pair (inc. VAT), £2.20 p. and p.
Duo Type Ill Size approx. 234.in. x 114in. x 94in. Drive unit 134in. x 81in. with H.F. speaker. Max. power
20 watts, 8 ohms. Freq. range 20Hz to 20KHz. Teak veneer cabinet. £3520 a pair (inc. VAT) - £3.30 p. & p.
SPECIFICATION R102 : 20 watts per channel into 8 ohms (suitable 8-16 ohms.) Total distortion C@

10W ta 1kHz 01%. P.U.1 (for ceramic cartridges) 180mV into 3 Meg. P.U.2 (for magnetic cartridges)
4mV @ 1kHz into 47K equalised within 1dB R.I.A.A. Radio 180mV into 220K. (Sensitivities given at full
power). Tape out facilities: headphone socket, power out 250mW per channel. Signal-to-noise ratio:
(all controls at max.) -58dB. Cross talk better than --40dB on all inputs. Size approx. 131in. 9in. + 31in.
Send S.A.E. for fully illustrated brochure. 12 month's written guarantee.

ONLY FROM US
TIMES OF OPENING: Acton-Mon.-Sat. 9.30-5.
Closed all day Wed.
Edgware Rd.-Mon.-Sat. 9.30-5. Closed all day Thurs

209

www.americanradiohistory.com
 VISIT LONDON'S LIGHTHOUSE PRINTED CIRCUIT KIT
BUILD 60 INTERESTING PROJECTS on a PRINTED CIRCUIT CHASSIS with
PARTS and TRANSISTORS from your SPARES BOX

our lighthouse keeper CONTENTS: (1) 2 Copper Laminate Boards 41in x211n. (2) 1 Board for Match-
box Radio. (3) 1 Board for Wristwatch Radio, etc. (4) Resist. (5) Resist Solvent.
(6) Etchant. (7) Cleanser/Degreaser. (8) 16 -page Booklet Printed Cireulla for Amateurs.
(9) 2 Miniature Radio Dials SW/MW/LW. Also free with each kit: (10) Essential

wants to meet you! Design Data, Circuits, Chassis Plane, etc. for 60 TRANSISTORISED PROJECTS.
A very enmpreheneive relee) inn of circuit., fo snit everyone's requirements.

EXPERIMENTER'S
Jim Roche has been Imhofs Eddystone light- PRINTED CIRCUIT KIT
house keeper for a good few years now - so who 70p
better than he toguideyouintotherightchannel, Postage & Pack. IOp (UK)
for an Eddystone communications receiver: Commonwealth:
SURFACE MAIL I5p
Model 1001 - general- AIR MAIL 60p
purpose receiver with Australia, New Zealand,
South Africa, Canada
reception facilities for
CW, MCW, AM and SSB (1) Crystal Set with biased Detector. (2) Crystal Set with voltage -quadruple. detector.
(3) Crystal Set with Dynamic Loudspeaker. (4) Crystal Tuner with Audio Amplifier.
Provision for crystal (5) Carrier Power Conversion Receiver. (S) Split -Load Neutralised Double Reflex.
(7) Matchbox or Photocell Radio. (8) ' TRl-PLEXON" Triple Reflex with sell -
control on 10 channels, adjusting regeneration (Patent Pending). (9) Solar Battery Loudspeaker Radio.
The smallest 3 designs yet offered to the Home Constructor anywhere in the World.
3 Subminiature Radio Receivers based on the "Triflexon" circuit. Let us know
if you know of a smaller design published anywhere. (10) Postage Stamp Radio.
Size only 1-62in x 095in x 0.25in. (11) Wristwatch Radio 1.151n x 080in x 0-55in. (17)
Ring Radio 0-70in x0-70in x0-55in. (13) Bacteria -powered Radio. Runs on sugar or
EC10 Mk II still 'Top of bread. (14) Radio Control Tone Receiver. (15) Transistor PIP Amplifier. (16) Inter-
com. (17) 1 -valve Amplifier. (18) Reliable Burglar Alarm. (19) Light -Seeking Animal,
the Pops' in the modest Guided Missile. (201 Perpetual Motion Machine. (21) Metal Detector. (22) Transistor
Tester. (23) Human Body Radiation Detector. (74) Man/Woman Discriminator.
price rangeofcommuni- (25) Signal Injector. (26) Pocket Transceiver (Licence required). (27) Constant
Volume Intercom. (28) Remote Control of Models by Induction. (29) Inductive -Loop
cation receivers. Em- Transmitter. (30) Pocket Triple Reflex Radio. (31) Wristwatch Transmitter/Wire-less
Microphone. (32) Rain Alarm. (33) Ultrasonic Switch/Alarm. (34) Stereo Pre-
bodies features usually amplifier. (35) Quality Stereo PushPull Amplifier. (36) Light -Beam Telephone
only found in the more "Photophone". (37) LightBeam Transmitter. (38) Silent TV Sound Adaptor. (39)
Ultrasonic Transmitter. (40) Thyristor Drill Speed Controller. (41) Light Dimmer.
expensive designs. (47) I.C. Pre -amplifier. (43) I.C. Amplifier. (44) I.C. Intercom. (45) I.C. Radio. (46)
Raudive Voices Receiver. (47) Biofeedback Amplifier. (48) Brainwave Detector.
(49) Proximity Switch. (50) Laser Projector.
New Oxford Street
znrxON's 112-116
London WCIA 1HJ
telephone 01-636 7878 R81
Plus 10 Photoelectric Circuits, Simple Alarms, Long Range Alarms, Projector, etc.

YORK ELECTRICS, Mail Order Dept.

335 BATTERSEA PARK ROAD, LONDON, S.W.11
Send a S.A.E. for full details and a brief description of all hita and Projets.

Train for ALL PRICES INCLUDE VAT

BARGAIN PARCELS 14íb at £1.60 plus 35p p.D.: 28Ib at £3.00 plus
571,p p.p.; 561b at £4 95 plus £1.37; p.p. Contain pots, Res. Valves, Diodes
Tagboards, Chassis, Valveholders, etc. Good value save £££s. Lucky Dip

televisio
Service.
FANTASTIC BARGAIN. New 6 inch tubes. E450 4/B/16 4VH, medium
Persistance, green. Ideal scope tube.
Also 093 4#M. dia. Length 15in, Also 7BP7. All unused as new. Price £1.55
post paid.
NEW HEAVY COAX CABLE dia. 1" 70 ohms approx. 50ft. lengths £I.55,
p. & p. 32fp. 100 ft. lengths £2.97, p. & p. 55p.
Course commences 5th September, 1973 AERIALS. New Condition Whip Type, 4ft. 22p; I I ft. 821p. all collapsible
type. P. & p. 4ft. 10p, Ilft. 15v. New bases on adjustable clamp for the
This is your opportunity to train as a television above, 67fp. p. & p. 27fp.
and radio engineer on our full-time Two -Year CRYSTALS AS NEW. He 6u, 5,345; 5.030; 4.945; 4,875; 4,840; 4.795;
College Diploma Course specially designed to cover 4,580; 4,660; 4,520; 4,510; 2,295 Kc/s. 55p each plus 8p p.p.
the examinations of the City and Guilds Radio, OUR SELECTION OF 6-Ex. Equ. METERS consisting of 3jn., 24M.. tin.
Television and Electronics Technicians' Certificate. mill amps, volts, amps. Mixed at the bargain price of £2.20 P. & P. 274p,
Full theoretical and practical instruction on all types minimum order of six.
of modern receivers-including the latest colour sets. ANY HEIGHT AERIAL TUBULAR SECTIONS 1" dia, x 3ft. long. Brass
screw in ends, copper coated and painted. Good condition. 224p p. & p. 5p
Minimum entrance requirements are Senior each. Minimum order 6.
Cambridge or 'O' Level, or equivalent In Mathematics TELE 'J' TELEPHONES AS NEW £8.00 pair, p. & p. paid
and English. AS NEW AERIAL TUNER UNIT No. 6 RF, consisting of 14 inch 500 mice.:
ampmeter 3 gang tuner 75 PF geared BNC type socket size 51" x 41" x
5". Price £1 -65, p. & p. 274p.
NEW AERIAL WIRE ON BOARDS 7/22 UNCOVERED 9Oft 50p, 100ft.
Please send free prospectus to: 60p, p. & p. 22p.
AERIAL MAST POLES approx. 5ft high 2" dia. Interlocking ends. Mini-
IName mum order three. New condition, £1 10 each section. Carriage 374p each
section. 4" 75 ohms Coax in 50ft coils with BNC plugs good condition.
Price £1.10 + 324p p.p.
IAddress AS NEW 500ua PENNY SIZE METERS complete with jack plug price
£1.10 each, p. & p. 10p.

I C.W.O. CARRIAGE CHARGES MAINLAND ONLY

WOULD CUSTOMERS PLEASE ENSURE THAT ALL ORDERS ARE
PRINTED IN BLOCK CAPITALS AND INCLUDE YOUR ADDRESS.
I
I THE PEMBRIDGE COLLEGE OF ELECTRONICS I A. H. THACKER & SONS LTD.
'----------mug
210
(Dept. PW4) 34a Hereford Rd., London W2 5AJ
Radio Dept., High Street, Cheslyn Hay,
Staffs.
Nr Walsall,

www.americanradiohistory.com
 ALL OUR PRICES INCLUDE V.A.T.
BSR LATEST SUPERSLIM ANOTHER RCS BARGAIN! Hi-Fi ALL MODELS "BAKER SPEAKERS" IN STOCK
Enclosure Manual containing 20 plans, designs,
crossover data and cubic tables. 42y. Post Free
Transistor Mono Amplifier
STEREO AND MONO
Plays 12", 10" or 7" records.
Auto or Manual. A high
4
Powerful 3 watt output. 15 ohm. AC mains operated with
transformer. 3-Controls, volume, treble, bass and On(011
BAKER I hin. MAJOR f 10
P. & D. 25D
quality unit backed by BSR switch with knobs. Ready made on printed circuit board. 1 30-14,500 c.p.s., 12in. double
reliability with 12 months' Fused inputs and outputs. Famous make. cone, woofer and tweeter cone
guarantee. AC 200/250v. Sise Sin. wide x 4 in. deep 3in. high. together with a BAKER
Size 131 x 111in.
Above motor board Slin. Suitable 7" x. 4" speaker, £1. PRICE E5.95 P3asD ceramic magnet assembly
having a flux density of
Below motor board 21ío.
With STEREO and MONO XTAL £825 Poil 25p. 14,000 gauss and a total flux
R.C.S. STABILISED POWER PACK KITS o1 145,000 Maxwells. Baas
All parts and instructions with Zener Diode, Printed Circuit. resonance 40 c.p.s. Rated 20
PORTABLE PLAYER CABINET Bridge Rectifiers and Double Wound Mains Transformer watts. NOTE : 3 or 8 or
Modern design, black rexine covered. L4.50 input 200/240v. AC. Output voltages available 0 or 9 or 15 ohms must be stated.
silver front grille. Suitable for above player. Poet 25p. 12 or Ib or 18 or 20v. DC at 100mA or less.
PLEASE STATE VOLTAGE REQUIRED. POST Module kit, 30-17.000 c.p.s.
Details S.A.E. Size 34 >: 14 x 11ín. £2.20
15p
EM.!. TwEETEROOFER AKIT £5.15 i with tweeter crossover, baffle
and instructions.
Available separately
DD
Post 260 GENERAL PURPOSE TRANSISTOR P. & p. 25P.
£12.50
Woofer 24.25, Tweeter £1.90.
Comprising a fine example of a Woofer PRE -AMPLIFIER BRITISH MADE BAKER "BIG-SOUND" SPEAKERS P. & P. 25P
102 x Blin. with a massive Ceramic Ideal Ior Mike, Tape, P.D., Guitar. Can be used with
Magnet, 44oz. Gauss 13,000 linen. Battery 9-12v or H.T. line 200-300v D.C. operation. 'Group 2p5'p 'Group 3p5's4 'Group 50'
Size 13" x 11" x I". Response 25 c.p.s. to 25 Kc/s. 28db gain. 12 12 inch
25 watt £BBO 85 watt £7'70
Aluminium Cone centre to improve £22
middle and top response. Also the E.M.I. For use with valve or transistor equipment. 50 -watt
Tweeter 31in. square has a special light- Full instructions supplied. Details S.A.E. 99 P Postlop 3 or8or 15 ohm 3or8or15 ohm 8or16 ohm
weight paper cone and magnet flu
10,000 lines. Crossover condenser and NEW ELECTROLYTIC CONDENSERS TEAK VENEERED HI-FI SPEAKER CABINETS
full instruction supplied. For 12in. or loin. dia, speaker 20 x 13 x 9'n. £9.90 Post 25p
8 ohms 2/850V .. 140 200/21V .. lip 60+50/350V .. 860 For 13 x Bin. or Bin. speaker 18 - 10 x Bin. £5.50 Post 20p
Impedance Standard 4/850V 14p 500/26V .. 20p 80 +100/850V .. 58p
Maximum Power 12 watts For 8 x lin, speaker 18 - 8 x Bin. £4.40 Post 250
35 to 18,000 cps 8/450V .. 14p 1000/25V .. 36p 82-4 32/250V .. 180 For Bin. and tweeter 12 x 8 x 8in. £4 Post 25p
Useful Response 18/450V 16p 1000/50V .. 47p 82+32/460V .. 830
Bass Resonance 45 cps LOUDSPEAKER CABINET WADDING 18in, wide, 15p ft.
82/450V 20p 8+0/450V.. 18p 860+50/325V 500
SUITABLE ENCLOSURE 20 x 13 x gin. £9.90 POST 25p
.

25/25V .. 10p 8-113/450V 200 82-82+32/850V 480

MODERN DESIGN TEAK WOOD FINISH 50/50V .. lop 18+18/450V 25p 100+50+50/150V 48p GOODMANS 62ín. HI-FI WOOFER £4
100/25V lop 82+82/350V 25p 8 ohm, 10 watt. Large ceramic magnet.
SPECIAL OFFER Special Cambric cone surround. Frequency
SMITH'S CLOCKWORK 15 AMP LOW VOLTAGE ELECTROLYTICS response 30-12,000 cps. Ideal P.A. Columns.
TIME SWITCH 1, 2, 4, 5, 8, 16, 25, 30, 50, 100, 200mF. 15V. 10p. Hi-Fi Enclosures Systems, etc.
Single pole two-way. 500mF. 12V. 15p; 25V. 20p; 60V. 80p. Suitable Cabinet 12 8 x 0, 24.00.
Maker's last list price £4.50. 1000mF. 12V. 170; 25V. 85p; 50V. 47p; 100V. 70p. Suitable Tweeter, £2 00.
Brand new and fully guaranteed. 2000mF. 8V. 25p; 25V. 42p; 50V. 67p.
Surface mounting with fixing screws. 2500mF. 60V. 82p; 8000mF. 25V. 47p; 50V. 86p ELAC CONE TWEETER
Will replace existing wall switch to give light for return 5000mF. 8V. 25p; 12V. 42p; 25V. 75p; 35V. 85p; 00V. 95P.
The moving coil diaphragm gives a good
home, garage, automatic anti -burglar lights, etc. Variable radiation pattern to the higher frequencies
knob. Turn on or off at full or intermediate settings. CERAMIC 1pF to 0 OlmF, 4p. Silver Mica 2 to 6000pF, 40 and a smooth extension of total response
TWO TYPES AVAILABLE 0 TO 80 MINUTES OR 0 PAPER 850V-0.1 4p, 0.5 18p; 1mF 15p; 2mF 160V 15p. from 1,000 cps to 18,000 cps. Size 31 x
TO 8 HOURS. OUR PRICE £1.50, P. & P. 15p OR £3 000V-0001 to 0 05 4p; 0 1 61); 0 25 8p; 0.47 25P. 38 x 2in. deep. Rating 10 watts, 3 ohm
PAIR. (STATE TYPE A OR B WHEN ORDERING.) SILVER MICA. Close tolerance 1"; 2 2-SOODF 8p; 500-2,200
pF 10p; 2,700-5,600pF 20p; 8,800pF-0.Olm F 30p; each.
or 15 ohm models.
Crossover, 95p. £ I.90 Post lOp
WEYRAD P50 -TRANSISTOR COILS TWIN GANG. "0-0" 208pF+178pF, 650; SOOpF standard
RA2W Ferrite Aerial.. 72p Spare Cores 8p 45p; 385--305 with 25 -25pF Slow motion drive 50p. SPEAKER COVERING MATERIALS. Samples Large S.A.E.
Osc. P50/1AC 39p Driver Trans. LFDT4 58p SHORT WAVE, SINGLE. 10pF 30p; 26pF 55p; 60PF 65p Horn Tweeters 2-18kc/s, 10W 8 ohm or 15 ohm 21.95.
NEON PANEL INDICATORS. 250V AC/DC Amber 20p. De Luxe Horn Tweeters 2-18 Kc/s, 15W, 15 ohm 23.
I.F. P50/2CC 470 kc/e. 36p Printed Circuit, PCA1 68p
TWO-WAY 3000cps CROSSOVERS 3 or 8 or 15 ohm 85p.
8rd I.F. P50/3CC 38p J.B. Tuning Gang.... 615P RESISTORS. 1 w., 8 w., 1 w., 1p; 2 w., 5p 10 ohms to 10 meg
.
LOUDSPEAKERS P.M. 3 OHMS. 7 x 4in. £1 25; Ohin. £1.50;
.

P51/1 or P51/2 38p Weyrad Booklet 10p HIGH STABILITY. 8 w. 10 ohms to 8 meg., 10p.
Ditto 5' Preferred values 10 ohms to 10 meg., 4p. 8 x Sin. £1'60; loin. 2200; 8in. £1.75: 10 : Sin. £1.90; 101n.
P50/3V 38p OPT1 580 £2.00. SPECIAL OFFER: 80 ohm, II in.; 21in.. 35 ohm, 2in..
WIRE -WOUND RESISTORS. 6 watt, 10 watt, 15 wet
Mallard Ferrite Rod 8 tin. 20p, 8 r. lin. 200. 0 ohms to 100K 10p each; 21 watt, 1 ohm to 8 2 ohms lop 3in., 25 ohm, 21in. dia.; 3in. dia. 5in. dia. £ I
- EACH
TAPE OSCILLATOR COIL. Valve Type 85p. 15 ohm, 35in. dia.; 8 x 4in.; 7 x 4in.; 8 x 5in. TYPE
3 ohm, 24in.; Mo.; Ilia.; bin. dia. (8 4in. 8 ohm £1.50/
VOLUME CONTROLS 80 ohm Coax 4p. yd. RICHARD ALLAN TWIN CONE LOUDSPEAKERS.
5 K. ohms to 2 Meg. LOG or BRITISH AERIALITE GARRARD DECCA DISCO DECK 8in. diameter 4 watt; 10in. 5 watt; 12in. 8 watt 3 or 8
AERAXIAL-AIR SPACED or 15 ohm models £2 20 each. Post 15p.
LIN. L/S 15p. D.P. 25p.
STEREO L/S 55p. D.P. 75p.
40 yd. £140; 80 yd. £2.
FRINGE LOW LOSS £I8.50 É6' VALVE OUTPUT TRANS. 25p; MIKE TRANS. 50:1 25p.
5 WATT MULTI -RATIO. 3, 8 and 15 ohms, 80p.
Edge SK.S.P. Transistor 25p Ideal 825 & colour 1 Op yd. Single Play Stereo Mono
Deram transcription MAJOR 100 WATT
head and arm. Four
8in & I Oin ELAC speeds. !Olin. turn-
table. Anti -rumble
ALL PURPOSE
HI-FI SPEAKERS filter. Bias compen- TRANSISTOR
Dual cone plasticised roll sation. Laboratory AMPLIFIER
surround. Large ceramic motor.
magnet. 50-18,000 cps. 4 Inputs speech and
Bass resonance 55 cps. music. 4 way mixing.
8 ohm cot. BRITISH FM/VH? TUNING HEART Response 10-30,000 cps. Matches
8in. 10 watt,
loin. 12 watt
music power. £3 e po75et
25p
88 to 108 Mc/s British made. 2 Tran-
sisters ready aligned- -requires 10.7
Mc /a IF. Complete with tuning gang.
Our Price
£3.95
loudspeakers 8/I5 ohm. A.C. 200/
250V. Separate Treble and Bass
controls. Guaranteed. Details S.A.E. £49 Post.
Free
Connections supplied but some tech-
E.M.I. 13+ 8in. nical experience essential. Post 20p. BARGAIN AM TUNER. Medium Wave.
Transistor Superhet. Ferrite aerial. 9 volt. £4.95
SPEAKER SALE! ALL POSTB BARGAIN 4 CHANNEL TRANSISTOR MONO MIXER.
With twin tweeters MAINS TRANSFORMERS Add musical highlights and sound effects to recordings.
and crossover, 10 watt.
State 3 o 8 o 15 ohm. £4.50 Eagle MT12 12-0-12 v
ch
00p
250-0-250 80 mA. 9.8 v. 8 5 a. 8.8 v. l a. or 5 v. 2 a £2.60
Will mix Microphone, records, tape and tuner £3.95
with separate controls into single output. 9 volt.
(As illustrated) Post 25p 350-0-850 80 mA. 8.3 v. 8 5 a. 88 v.1 a. or 6 v. 2 a £300
800-0-800 v. 120 mA., 68 v. 4 a. C.T.; 8.8 v. 2 a £825
STEREO VERSION OF ABOVE £5.95
With Oared tweeter cone and ceramic MINIATURE 200 v. 20 mA., 8.8 v. 1 a. 25 x 24 x Sin. 75p
magnet. 10 watts. BARGAIN FM TUNER 88-108 Mc/e Six Transistor. 9 volt
MIDGET 220 v. 46 mA., 8 3 v. 2 a. 21 x 28 x 2in. 90p
Bass res. 45-80 cps.
Flux 10,000 gauss. 2.75 HEATER TRANS. 8.8 v. 8 a
GENERAL PURPOSE LOW VOLTAGE, Tapped Outputs
600
Printed Circuit. Calibrated slide dial tuning.
Walnut Cabinet. Sise 7 x 5 x 4 in. £ 14.85
State 3 or 8 or 15 ohm. Post 25p at 2 amp. 8. 4, 6, 8, 8, 9, 10, 12, 15, 18, 24 and 80 v. £2.25 BARGAIN FM TUNER as above lees cabinet £9.85
TEAK CABINET £5.50 gyp 18x10x91a. 1 amp. 8, 8, 10, 12, 18, 18, 20, 24, 80, 88, 40, 48, 60, £2.25
8 WATT AMPLIFIER. 4 Transistor
2 amp. 6, 8, 10, 12, 18, 18, 20, 24, 80, 86, 40, 48, 60, £8.25
6 amp. 6, 8, 10, 12, 16, 18, 20, 24, 80, 88, 40, 48, 80. £8 75
BARGAIN
Push-Pull Ready built, with volume control. 8v. £4.50
BRITISH MADE STEREO 8 amp. 5, 8 and 18 v. 2100; Ditto 6 amp. £120.
COAXIAL PLUG 10p. PANEL SOCKETS 10p. LINE 18p
MULTIPLEX DECODER 8 amp. 8, 5, 8, 10, 18 and 6-0-5 v. £1.80; Ditto 6 amp. £1-S0
AUTO TRANSFORMERS 115v. to 280v. or 280v. to 116v. OUTLET BOXES. SURFACE OR FLUSH, 250.
Brand New. 7 transistors plus integrated 160w. 22.25; 600w. 2825; 750w. £10; 1000w. £15. BALANCED TWIN RIBBON FEEDER 300 ohms Op yard
circuit. Fibre glass printed circuit board. CHARGER TRANSFORMERS. Input 200/250 v. for 8 JACK SOCKET Std. open -circuit 14p, closed-circuit 23p.
Size 21 x 84 x Ito. Pre -aligned. Com- or 12 v., 14 amp. £1.50; 2 amp. £1.80; 4 amp. 82.60. Chrome Lead Socket 45p. Phono Plugs 5p. Phono Socket 5p
plete with stereo beacon indicator. 12V FULL WAVE BRIDGE CHARGER RECTIFIERS: JACK PLUGS Std. Chrome 15p; 9.5mm Chrome 12p. DIN
d.c. operation. 40nmV output for 100µV 6 or 12 v. outputs, 14 amp. 40p; 2 amp. 55p; 4 amp. 850. SOCKETS Chassis 3 -Din 10p; 5 -pin 10p. DIN SOCKETS Lea
input. Full instructions for any FM Tuner. BATTERY CHARGERS. 15A. £2; 3A £3; 4A £4. 5A. 24.50 3 -pin 18p; 6 -pin 25p. DIN PLUGS 3 -pin 18p; 5 -Din 259
Some technical experience Post VALVE HOLDERS, 5D; CERAMIC 8p; CANS 5p.
essential. £6.95 15p
LUCAS 205500 Full wave Bridge 70V 5 amp 95p.
FACTORY ACT! MAINS ISOLATING TRANSFORMER ONE RPM GEARED MOTOR
BLANK ALUMINIUM CHASSIS 18 I.W.R. 2in. sides. 8 x 4in Primary 0-110-240 v. Secondary 0-240 v. 3 amps. 720
240v. A.C. mains. Ideal for displays/discos
95P t.
45p; 9 x 7in. 80p; 11 x 7in. 70p; 13 x gin. 90p; 14 x 11ín. watts. Insulated terminals. Varnish impregnated. Fully
95p; 15 x 14in. 99r; 11 x lin. 50p; 18 x loin. £1. enclosed in steel case with fixing feet. Famous make. E.M.I. GRAM MOTORS
Value £19. OUR SPECIAL PRICE Carriage
ALUMINIUM PANELS 18 a.w.g. 8 x 4Sn. 9p; 8 x ein. 150; £ 10 120v. or 240v. A.C. 2,400 rpm. 2 -pole £1.00
14 x 3in. 16p; 10 x 7in. 19p; 12 x 5in. 20p; 12 x Sin. 28p;
watt Auto Transformer 240-110V. 70mA. Spindle 3 x Ain. Size 2; x 21
8in.28p;14 Can be used as 800 Post 25p.
18 x x 9in.34p;12 x 12in.400;18 x lOi11.50p x 21in.

WHITEHORSE ROAD, CROYDON

RADIO COMPONENT SPECIALISTS Open 9-6
337
Wed.9-I Sat. 9-5 (Closed for lunch 1.15-1.30)
Minimum post 15p. Radio Books & Components Lists IOp. Illustrated Colour Brochure Buses 50, 68, 159 Rail Selhurst. Tel. 01-684-1665.
211

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 TOP QUALITY - LOW COST 11= ® RADIO - STEREO EQUIPMENT

P.R.40
SOLID STATE
R.F. PRESELECTOR
The PR40 R.F. Preselector is the solid state version of the world famous
PR30 which it now supercedes.
It employs Silicon "N" Channel FET (Field Effect Transistor) front end,
followed by silicon NPN Broad Band R.F. Amp., and will substantially improve
receiver performance over the range 1-5 to 35 MHz, providing a considerable
increase in gain up to an overall avenge of 30 dB, with improved image
CR70A
COMMUNICATION RECEIVER
rejection and noise ratio.
Supplied complete with co -ax plug (less standard 9 volt PP6 Battery), 12
The CODAR CR70A is an outstanding general coverage communication
months Guarantee. £10.12 V.A.T./Carr. paid.
receiver, ideal for the keen S.W.L.
It tunes from 540 metres medium through to 10 metres with no gaps.
Covers shipping, coastguard and distress frequencies, all six amateur
bands 160-10 metres, International broadcast, Met. stations etc. etc.
NEW! HI-FI STEREO EQUIPMENT giving world-wide reception. Exclusive features include Air-spaced
CODAR-COIL Hi -'Q" Aerial input, illuminated Meter and Slide
Rule Scale, Two Speed vernier tuning, Switched B.F.O. for CW/SSB
NOW AVAILABLE FROM CODAR-A COM- signals. Separate output for Tape recorder.
Ready to plug in to 200/240 volts A.C. it only needs your aerial and a
PLETE RANGE OF QUALITY EQUIPMENT 2/3 ohm loudspeaker to bring the world to your finger tips. 12 months
SELECTED BY US FOR TOP RESULTS AND full guarantee. Complete ready built. £31.00 V.A.T./Carr. paid.

MONEY VALUE -PLUS OUR BIG CASH SEND FOR YOURS TODAY!
FREE LEAFLETS ON REQUEST.
DISCOUNTS!
NOTE: These CODAR Receivers meet the B.R E.M.A. specification
for Communication Receivers. Some portable receivers being advertised
SEND FOR FREE ILLUSTRATED BROCHURE NOW. as Communication Receivers do not meet these requirements.

ON THE DESIGN STAFF-

G3SZM G3I RE CEDAR TELECOMMUNICATIONS AND ELECTRONIC
EQUIPMENT SUPPLIERS TO H.M. AND OVERSEAS
GOVERNMENTS
VALCON WORKS BURRELL BUILDINGS CHURCHILL INDUSTRIAL ESTATE LANCING SUSSEX
Tel. 090-63-61901 BNI5 - 8TZ

FIRST TIME EVER WOBBULATOR D.I.Y. TECHNICAL BOOKS

Sweeps 8 to 45MHz ready to use. RADIO RECEIVER SERVICING GUIDE .. .. .. .. £1 90
at £42.50 6.3V a.c. required. £9 each. P. 6 P. 101 EASY HAM RADIO PROJECTS .. .. .. .. £1 50
Solartron CD711S.2 25p. (Not cased, not calibrated.) 101 EASY AUDIO PROJECTS .. .. ..
CAPACITOR PACK -50 Brand new £1.40
Double Beam RAPID T.V. REPAIR (224 pp) ..
- -- £1 30
Oscilloscope d.c.-9MHz; 3mV- components only 50p. P. & P. 17p. ELECTRONIC GAMES AND TOYS YOU CAN BUILD .. £1 40
cm; trigger delay; crystal call/ POTS-10 different values. Brand PAL RECEIVER SERVICING GUIDE (280 pp) £3 50
brator; 41n flat faced -tube. In new -50p. P. 6 P. 17p. BASIC ELECTRICITY (5 VOLUMES, 630 pp, 600 ILLUS.)
COMPONENT PACK consisting of £S-10
good working condition. Carriage ELECTRONIC DESIGNERS HANDBOOK £;-4g
£150. 2.2 pole 2 amp push on/off switches; BASIC ELECTRONICS (6 VOLUMES, 674 pp, 700 ILLUS.) £510
HARTLEY TYPE 13A 4 pots, various, brand new; 250 ELECTRICITY, ELECTRONICS MADE SIMPLE .. ..
Only £1800 f f
resistors and watt, many high stabs, RADIO HANDBOOK (896 pp)
Each 95p
£g 50
Double Beam oscilloscope etc. Fine value at SOp per pack. 1-2-3-4- SERVICING STEREO AMPLIFIERS (240 pp) ..
P. 6 P. 17p. £2 50
TB2Hz-750kHz. Band width MAKING & REPAIRING TRANSISTOR RADIOS, ADVANCED
5.5MHz. Sensitivity 33Mv/cm. P.C.B. PACK S 6 D. Quantity 2 so RADIO CONTROL, EASY WAYS TO SERVICE RADIO RE-
Calibration markers 100kHz and ft-no tiny pieces. 50p plus P. 6 P. CEIVERS, BEGINNERS GUIDE TO T.V. REPAIR, PRACTICAL
20p. HAM RADIO PROJECTS, HI - Fl PROJECTS FOR THE
1MHz. A completely reliable
general purpose oscilloscope. FIBRE GLASS as above £1 plus HOBBYIST Each £1.00
Supplied with CIRCUIT DIA- P. 6 P. 20p. HOW TO BUILD SPEAKER ENCLOSURES £1.50
GRAM and Mains lead. Carr. 5 CRYSTALS 70 to 90kHz. Our choice, HI - Fl STEREO SERVICING GUIDE, 99 ELECTRONIC PROJECTS,
SOp. P. & P. 15p. 99 WAYS TO IMPROVE YOUR HI - Fl
£150. Matched pairs, SOp Each £1.50
per pair. P. & P. ELECTRONICS FOR THE BEGINNER, T.V. SERVICING MADE
As above. Complete with all 15p.
accessories. £2500. Carr. £1.50. EASY, 101 QUES. & ANSWERS ABOUT AM, FM & SSB Each £1.75
TRIMMER PACK. 2 Twin 50/200pF HOW TO REPAIR SMALL APPLIANCES .. £1.20
Many other oscilloscopes avail- ceramic 2 Twin 10/80pF ceramic;
able. 2 min strip with 4 preset 5/20pF on ADD 10% FOR POSTAGE AND PACKING
each; 3 air spaced preset 30/100pF on WHEEL (PWJ), 41A ADELAIDE GROVE, LONDON, W12
GRATICULES. 12cm x 14cm in Hi h ceramic base. ALL BRAND NEW,
Quality plastic. 30p ea. P. & P. 5p.
MODERN TELEPHONES type 706.
Two tone grey, £375 ea. The same
25p the lot. P. & P. 10P.
ELECTRONIC TIMER
wall or bench mounting -2 Hybrid
UNITS -
but black, £2 75 ea. P. & P. 25p ea. timer boards may be removed leaving
Also TOPAZ YELLOW £4.50 ea. excellent 12V battery charger; d.c.
P. & P. 25P. Power supply, etc. Price only £250
STANDARD GPO DIAL TELE- Incl. carriage.
PHONE (black) with Internal bell, AMERICAN SCOPE type USM24.
87p ea. P. & P. 50p. Two for £1.50. A 10 meg scope -all min valves BAKER 12" MAJOR £9.90
P. & P. 75p. All telephones complete complete with circuit diagram. Mains
with bell and dial. input 115 volt 50 cycles therefore 30-14500 cps. Double cone woofer and
20Hz to 200kHz WB £2000. Carr. £1.50. tweeter combination. Baker ceramic magnet
SINE AND SQUARE GENERATOR LIGHT EMITTING DIODES (Red) assembly flux density 145000 gauss.
Four ranges. Independent amplitude from Hewlett-Packard. Brand New
Bass resonance 40 c.p.s. 20 watt RMS.

£1 250
controls, thermistor stabilised. Ready 31p ea. Holder 1p ea. Information Sp.
to use. 9V supply required. £8-8S PHOTOCELL equ OCP71-13p e
each. P. 6 P. 25p. (Not cased, not PHOTO -RESIST type Clare 703.
.
MAJOR MODULE KIT
calibrated.)
MOTOR
Size 11-x
MIN SYNCHRONOUS
2' x }- 240V operation 3 8
RPM 25p each. P. 6 P. 5p.
Two for 50p.
DELIVERED TO YOUR DOOR
1 cwt of Electronic Scrap chassis,
boards, etc. No Rubbish. FOR
30-17000 cps. with
tweeter, crossover and baffle.
(
5 MOVING COIL METERS various ONLY £3 -SO.
£2 P. 6 P. 37p. Baker Loudspeakers
PLEASE ADD 10% V.A.T. Regent 12' 15W L8-80 Superb12-20WL16-50 I
Open 9 a.m. to 7.30 p.m. any day. Major 12' 20W L9 90 Grp.25 12' 25W £8 80 ALL PRICES
CNNLTMEAO
ARTHUR ROAD, READING,
7/9
L BERKS.
Deluxe 12' 15W LI I Grp. 35 12' 35W L9.90 INCLUDE VAT

Baker Loudspeaker Co., Bentham Manor Passage,

Thornton Heath, Surrey. Tel. 01-684 1665
(rear Tech. College) Tel.: Reading 582605/65916 Loudspeakers Catalogue and Enclosure plan Sp

212

www.americanradiohistory.com
ZN4/4 PosT
FREE £1.25 VDR's S Thermistors Potentiometers Capacitors
The I.C. Radio in a 7018 can. Supplied A15B 75p E298 EDIA258 10p VA1005 lop
complete with data sheet No. 10 which 1Sp E298 ZZ/06 10p VA1026 13p dise ceramic low voltage
CZ1 eta/ a t.. µF 30v Sp
contains specification, circuit and details VA1033 1OP 01µF Sp lo0.

and prices of components such as ferrite

CZ4
CZ13A13p
13p
VÁ1034 10p
VÁ1039 15P
_# r r--.
-...,
OlpµF 18v
047µF 12v
SP
Sp
0'22µF
0'47µF
0e
3v
5p
5p
rods, compression trimmers etc. CZ19 130 .
I.C.GL18£100 VÁ7040 100 ceramic plate 30V
C SocketsGL23£1'00 VÁ7053 100 5KD 50KS2 5001(S21000pí 160
100
4700pí
10,000pí
100
10

I R53 £1.32 VA1055S10p 2200pí

Dual -in -line or Zig -Zag Wudl 14 and 16 pin 10Kí1 100KS2 1M SI
R54 £1.46 VA1077 13p 2M
Our Price per pin 25K52 250KD Ceramic - plate 63V (C333)
lo or lin less switch (& 1K fl lin 12p 8pí 82Pí 3301 120pí
Sider Pots Resistors logg or lin with switch
dual less switch
)

400
p 2.2pí
33pf
10.Pí
12pí
39Pí
4701
150Pí
180pí
Single Dual log 4 watt 5% Carbon Film - low noise dual with switch 10K, 100K & 1M 39pf 15p1 56pf 220pí
Hi -Stabs log only 52p 4.7pf 18pí 68pf 270pf
I0K 10+ I0K or 10K log 10K outing less switch 40p
25K 25 + 25K lin
All E24 values 1p each plus p.6 p. 7p for up 5.6pf 22pí 82pf 330p1
to 50 Resistors and a further 2p for each 6 8pí 27pí 100pí
w
S00
100K
S00+
100+ 100K Knobs
additional 50. Deduct 33}% for 100 of one
type or 25% for mixed orders over £1 in value.
Eliminators all 5p. each

30p 50p 10p. 1 W 10% Carbon Composition 3p each mylar film 100V
2W 10% Carbon Composition Sp each 1000pf 2p 01pF 3p 068µF 4p
20W 5% Wire wound 9p each 2000pf 2p .020F 3p 'l pF 4p
NEW LISTS 5000pí 2p 04pF 3p '2µF 5p
LOUDSPEAKERS No.4 5W Wire wound 9p each
10W Wire wound 100 each '05pF 3p
COILS AND INDUCTORS No. 5

TRANSFORMERS No. Plus p. & p. 7p f up to 25 resistors plus 1 p

6
for each additionaloi 25. 01 at fine 160V
(pontage Sp) 1Ó0fta 10,000pí in multiples of 10, 15, 22, 33,
47 668. 3p each

Diodes 6 Rectifiers g sG5

Wiz.-o-^ ,.._
wetallised polyester
0.1 µF 3p '068µF
250V (C280)
34p .47pF 8p
015pF 3p '1 pF 4p 68pF 11p
ÁA119 8A156 15p9p 130176 £1.50 EA1000 6 volt u, 50mA £1.50 130
022µF 3p '156F 4p µF
AA120 BA243 56p9p BY182 £1 50 - 9 volt (n 50mA £1.50 033µF 3p 33µF Sp 1'5µF 200
AÁ129
BÁ102
0A47 10p
0A79 90
9p
25p
BY250 23p
N4001 6p
4rt 6 i-6 volt 50mA
9 i 9 volt, 50mA
£2.50
£2.50 047pF 3p pF 81p 22µF 24p
BA11517p 0A90 7p N4002 7p fw 74 volt for cassette recorders £2.00 metellised polyester 400V (C281)
BAI 3010p 0A91 7p N4003 8p fS 6, 74 or 9 volt
3. 45, 6. 74, 9, 12.'r 500mA (illus.)
£3.00
£3.99
-015F 44p '0475F 6p 22pF 10p
BÁ145 20p 0A200 10p N4004 Op - -015µF 44p '068pF Sp 33µF 14p
BA148 20p BY70015p N4005 10p a wan - Car Battery Convener fully
provide 6, 74 or 9 volts
stabilized to
£4.99
-022µF 44p 'lpF 7p 47µF 15p
BA154 13p 80126 15p N4006 12p Audio 033pF 55p '155F 8p
8A155 14p BY127 15p N4007 15p Amplifier (p. & p. 15p an all types)
ern mea sense tº. na Our Price Inc. handbool
silvered mica 1 % (>SOpf) 5609
g. N 2'2µ1-820p1 4.7nF S000pf lip

f
7p
1nF-2'2n1 6800pí -01µF 200
--rt - ,o+leee u%
2S+ lave 28%
í º Preset: 2'7n
tfic
mineddielectric
Op
lip
BO)V
l
'7i
FM TUNER
chu°sis fully toot leaº234% iO1pF 7p 047µF 7p 225F 16p
ar Vertical or Horizontal
' .4 9 voltntpdeed 0'1 watt 5p 025 watt 7p 022µF 7p 00685F Sp .475F 24p
5 Watt 0335F 7p .15F lµF 33p
100K it i! Sp
.

1` Au o !+p 100 1K11 10K f1 1M

OUR PRICE Ampnner 250 K º 25K 12 250K 21 2581 il
Matching
Ef
decoderFA an Dur Pa e E ºº
500 5K ii 50K il 500K ti 5M 12

Ask lo ,st No. 11. Lee º ant ,y discount.

MAIL ORDERS. Whets no p. & p. charge is shown,

N a minimum o1 7p applies, p& p on overseas orders
-id
p
1

0
11

..1111
II n
LltJ Ó _ electronics PRICES
INCLUDE V.A.T.
DO NOT °`"°'°°"°
ADDRESS TO: Component
$6, Fortis Green Road,
Telephone 01-883 3705
Dept.
London N 10 3HN

ixed dielectric
Neat Sinks Transistors 6 Integrated Circuits 000pí
2200pí 6p
6800pí
01µF
9p1pF
9p 22µF
12p
22p
AC107 Bp BCt47 10p sF196 I5p OCat rap 201300 22p 2Ns172 Isp 3300pf 6p '022pF 9p '47pF 30p
705 TOSS 14P ACt26 17p ecru. lip eF1a7 lip OCt40 Np 2Ntt11 2Sp LOOS, L1.5µ 470001 Sp 047µF 12p
TOTS '.7.- T03 15P AC127 e tep BC149 lep BF272 Sip OC170 23p 2141893 Sep LO3eT1 LI.50 Ce mit
4 , LIN BKV.d.C. HI -K 7509.

-15
'
5P Power AC121 tip BC,Si lap BFY50 SOP OCt71 30p 2142915 all 10p L03711
12K10.Pí

9p 200Pí 1000Pí 5p
Tab 13P AC1m lin BOUM up BFY51 alp zixloT fsp 2143053 23p MC1303L £815 22pf 9p 220µf 9p 1000pí 5p
1 AC187 26p RCUN tap BRYN Sep ZT%tOa lop 253054 sºp MC1330 Np 68pf 9p 250pf 9p 30000 5p
s, ACtnK 250 BC169 15v 135021 tep zixtN tsp 2N3055 411» Mc136o Isp 680 9p 27001 9p 300001 5p
^^^^ssyarrr

AC188 25p BC2311 typ BSY95A 14p ZTX300 lip 2143702 lap MC1351 El N 82pf 9p 300pí 9p 5000pf 5p
AC19wK 250 8D115 alp BUM/02 L1.78 ZT%301 15p 2143703 12p MC1352 al 00 10010f 9p 750V DISC 10,000Pf 5p
() f i ; f I

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ACY20 20p 60131 711p MJE340 lip ZTX391 20p 253704 lep MFCa0006 Np 120pí 9p 470pf 5p feed-
MPF192 Np asp IOp MFC4010A 140Pí 9p 10000 5p through

r jji tii
BDt32 7Oµ Z10363 2143705 sep
AD,N Np 5p

pW0
150Pí 500001
º^ 80149 Np 131:1,31/2M.P. MPF103 37p 210304 25p 2N3705 10p 181360 El 45
1E400
9P
9p 10,000pí 5p í(3000f 5p
ADO l Np
1Nµ MPF104 370 Z10341 200 2143707 150 PÁ234 £181

DEPIO/2`
for SI,403D
ADle1
AF114 lip
BF1N
BF167
51µ
20p
MPF105
MPFiN
4eµ
Np
ZT%500
ZTX501
I5p
lep
4143708
2143709
120
120
TADtoO
LILTER
Eta Mallard ß Siemens
AF115 12p .
BF113 Sep OC28 400 ZT%502 asp 2N3710 E1.50
E/ectro/yt cs
1185
1013 50p 15p n,
ÁF116 lip BF1W I5p OC35 Np ZT%503 tTp 2143711It,t 120 0Á10.0C 3 40

0aap00
Yerobeard AF117
ÁF139
18p
28p
BFIC1
BF1M
MI>
2Sµ
0C44
OC45
15p
15p
ZTX504
ZTX531
sep
25p 2539903 Sp pAnnZ3C
10 45p
Np ,.F
P
4 8.3 10
VOLTAGE
40 63
Copperclad Plain BC107 10p BF105 25p 0071 lIp PLANT tep 203904 17p pAia1C 470 r Bp
0,15" 0.15" BCtOa tap BF. 15p olio lip 214706 lop 2N3905 21p oA748C IMP 1.5 Op
3.2
BC109 10p BF1º5 15p OCIE í5p 2N706 15p 2143906 12p
la °p
6p
2S5" x 1" 6p 6p
4.7 6p
21/2" x 3%" 20p l60 (9) 10P Spöp
855" x
Ax334'
$" 24p
24p
21p (7)
210()
12p 10
- - - -ep eP

ep -!P Sp - ep Op 2p

Spot-face Cutter 36p - in

ep

-
- -
í22N0 Bp 6p 10p r ep 18p
Pin Insertion Tool
Terminal Pins
47p
18p per pad, of 36
ass
470
50
Lp
13p
'pp -
100
tep 18p
xlp
21p
40p

- -
gap 100 12p lap
top 1!p lep 210 sop Np

500
1000
NEW LISTS
-
1's'
1500 12
BOXES, CHASSIS etc No. 7 t 2200 lep 21p 40p 450 500 930
+.
-p
TRANSISTORS, I.C's etc- (soon)
3300
- -
^ no
., c 4700 21p Np inP
(505039e Sp) ,a } - 'r r CAP VOLTA ºE N a
Aluminium Noses
Including ha°eplate and screws
of
1250

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000 50
2000
No. L. W. D. Price p. & p. 2500
7eµ NO

P(IP
Np
Isp -
(7)
(8)
2%" x554" x
4" x 4" o
11/2"
165"
35p
35p
Sp
8p
Complete Kit (inc. Teak Case) Osa 45p
3200
a0
e400 7eµ 03e - -
930

Quantity Puces on eppuc.nsn

4" o 234" x In"
.

(9) 35p 8p 20 Watts pa channel integrated stereo amplifier developed by engineers of 'Texas Instruments Ltd.
(10) 4" x 5/4" x III" 40p lip This designer approved kit, has a state-of -the -ara specification, including distortion of only 0.09% at
II 4" x 215" 0 2" 35p Sp 20 Watts into 8 ohms and a bandwidth of 5 - 35,000 at -3db. The semiconductor compliment of Ni~Yo/t E/eetro/ytics
12 3" x 2" x I" 32p 9p this superb kit includes no less than 6 integrated circuits, 10 Silicon tttsmtors, 4 rectifiers and 1 2 4, Bel 450V 14p 327 450V 20p
13 6" x 4" x 2" 50p 10p 2 Nun. Controls cclude bus; treble; volume; balance; on/off; 'on' indicator; headphone sockets;
: 16µF 4500 15p 50µF 3505 20p
14 7" z 5" x 266" 58p I2p scratch filter; rumble filter; inputs for magnetic phono; tuner; aux or tape; tape head etc; input; 8 8,5: 450 V.W 160 32+320F; 350 V.W 25p
15 8" x 6" x 3" 75p 18p elector; mono/stereo switch. The construction of this kit was featured in 'Practical Wireless' e - 16µF; 450 V.W 20p 32 32pF; 450 V.19 43p
May - Aug. 1972. 16+1úµF; 450 V.W 25p 50' 50vF; 350 V.W 35p
16 10" x7" 03" 85p 20p

213

www.americanradiohistory.com
 COMEYHI-FI
discount warehouses
Rec. Retail Comet Rec. Retail Comet
Price Price All prices quoted in this Price Price
STEREO AMPLIFIERS £ p £ p advertisement Include VAT SPEAKERS-continued £ p E p
AKAI AA5200 87.45 6495 Rec. Retail Comet CLLESTION HADLEIGH (pair) 43.34 31-95
AKAI AA5500 10945 80 95
Price Price COUNTY (pair) 48-44 35 95
AKAI AA5800 164-45 12195 TUNERS/AMPLIFIERS-continued £ p E p Dicton 15 3896 29 50
ALBA UA 700 4172 27 95
PIONEER QX 9900 Quadraphonic Dittos 25 71.50 5150
AMSTRAD IC 2000 50-88 28 25 AM/FM/MPX 473.20 32750 Ditton 44 59-40 4295
AMSTRAD Integra 4000 39-05 2395 ROTEL RX 150A 6568 47.95 Dillon 66 10890 7975
FERROGRAPH F307 Mk. II (cased) 7480 4995 ROTEL RX 203A 84.10 0195 FERROGRAPH 51 Inc. stand 104.50 75.95
GLIXOR MW3000 15 watts RMS ROTEL RX 400A 10101 74.95 GOODMANS Minister (pair) 4833 33.95
per channel 5445 25.95 ROTEL RX 600A 140.01 10395 Havant (pair) 5377 34-95
GOODWIN RH 25 25 65-95 49-95 ROTEL RX 600A 178.07 131.95 Magister 72-19 43.05
JVC Nivico VN 300 69 85 5595 ROTEL RX 154A Quadraphonic 121.88
09.95 Double Maxim (pair) 63.45 4225
VN 700 SEA 14025 11295 SOLARVOX TAM 1105 2 x 5 watts Mezzo 3 3927 25-00
VN 900 SEA 169.40 13595 RMS AM/FM Multiplex comp Magnum K2 50.82 33-50
MCA 104Z 93.50 7485 with 2 speakers and featuring Goodwood 80.50 39-50
4DD5 Demodulator for CD4 67.10 S2 95
Matrix 4 channel 3706 29.75 Dimension 8 7968 5150
MCA V5E/VN550 Quadraphonic 104.50 8395 TANDBERG TR200 MPX (Teak) 112.20 93.95 DIN 20 NT Kit (pair) 2295 16.50
MCA V9E/VN880 Quadraphonic 17050 13695 TANDBERG TR1000 FM MPX (Teak) 183.71 139.95 KELETRON KS4 (pair) 22.66 14.50
VN 990 Quadraphonic 238.50 189 95 KS8 (pair) 2816 17.95
KELETRON KSA 700 Mk. II 31.10
TANDBERG TR1010 AM/FM MPX
20 95
(Teak) 177.33 148.95 KS8 (pair) 3630 23.50
KELETRON KSA 1500 Mk. ll 45.10 2795 TELETON CR55 116.53 64 95 KS10 (pair) 4688 30.50
LEAK Delta 30 (cased) 7689 5095 WHARFEDALE LINTON WE40 KS15 (pair) 6985 44 95
LEAK Delta 70 (cased) 9449 6320 AM/FM MPX 107.80 91.95 KS20 (pair) 78.76 50.95
METROSOUND ST20 Mk. II 46-20 32 95
All the above take magnetic cartridges except LEAK 150 (pair) 46.82 35 95
METROSOUND ST40 5940 4295 Kyoto 1000 which takes ceramic only. All include LEAK 250 (pair) 6086 46 50
METROSOUND ST60 77.00 5095 MPX Stereo Decoder. LEAK 800 54.45 34 50
PHILIPS RH 520 85.00 6995 METROSOUND HFS 103 (pair) 27.50 19 95
RH 521 11990 9695 202 2365 14.95
PIONEER SA500A 55-98 38.95 TURNTABLES Duplex 15 3520 26-95
SA600 113-43 73.95 CONNOISSEUR 601 Kit Chassis 1265 1050 Duplex 25 6160 42.95
SA800 150.34 103.95 CONNOISSEUR BD2 Chassis 31.02 24.05 PIONEER CS53 56.52 30.95
SA1000 185.12 12195 CONNOISSEUR BD2 P/C/SAU2 39.18 32 25 ROGERS Revensbourne Compact
SA6200 114.40 7895 GARRARD SP25 Mk. Ill Chassis 15.25 9 05 (pair) 61.60 49.95
SA7100 144.10 9995 GARRARD 406 Chassis 12.85 9 50 SINCLAIR Q16 8.47 9.20
SA8100 202.40 13995 GARRARD SL85B Chassis 18.78 12 95 SOLARVOX TK19S twin speaker
SA9100 248.00 171.95 GARRARD SL95B Chassis 46-40 3080 20 watts Teak (pair) 40.65 29.53
QL600A Quadraphonic GARRARD 401 Chassis 40.43 2610 TANDBERG TL 12 Teak (pair) 55.80 40.98
Convertor 141.32 96 95 GARRARD SL72B Chassis 3073 20 25 TL 25 Teak (pair) 75.16 91.96
QD210 Quadraphonic GARRARD AP76 Chassis 2682 16 95 TL 50 Teak 78.70 4196
decoder 50-01 33 95 GARRARD Zero 100A Chassis 51.57 3880 THORPE GRENVILLE TG700 (pair) 31.86 19.98
QA800A Quadraphonic 24992 172 95 GARRARD Zero 1005 Chassis 4744 3425 TG200 (pair) 46.16 28.84
QC800A Pre -amp Quad- GOLDRING 0101 P/C 31.35 21 50 TG300 (pair) 61.55 3489
raphonic 17831 12295 GOLDRING GL72 Chassis 34.65 2395 WHARFEDALE Denton Mark II
QM800A Pow. amp GOLDRING GL72P 45-87 31 50 (pair) 39.33 28.95
Quadraphonic 212-14 14695 GOLDRING GL75 Chassis 43.89 2995 Linton Mark II (pair) 48.69 33.99
Reverberation 202w 85.25 4495 GOLDRING GL75P 56.76 3895 Triton Ill (pair) 60.85 41.98
RANK ROTEL 210 3839 2850 GOLDRING GL78 Chassis with Melton Mark 11 38.50 28.98
RANK ROTEL 310 57.20 39 95 auto stop 5346 3695 Dovedale 3 Mark 1I 52.25 35.98
RANK ROTEL 610 8635 56 75 GOLDRING GL78P/Cover with Unit 3 speaker kit (pair) 23.40 1660
RANK ROTEL RA 810 116.05 8350 auto stop 76-89 5295 Unit 4 speaker kit (Pair) 41.80 29.28
RANK ROTEL RA 1210 141.90 10195 GOLDRING GL85P/Cover 9834 65.95 Unit 5 speaker kit (pair) 60.50 42.89
ROGERS Ravensbrook Mk. III McDONALD MP60 Chassie 1396 8.50
(cased) 63.25 49 95 McDONALD 610 Chassis 17.71 11 -50
ROGERS Ravenabourne 7700 5950 McDONALD HT70 Chassis 1949 12 50
CHASSIS SPEAKERS
Revensbourne (cased) 82-50 6495 GOODMANS Twin -axiom 6 8.58 425
McDONALD 710 Chassis 33.44 2150 Twin Axiom 10 9.47 0.98
SINCLAIR2000 3850 26 95 McDONALD 810 Chassis 41-80 2750
3000 4950 34 95 PIONEER PL12D with base and cover 51.90 Axiom 401 1945 13.98
35 95 Audlom 8P 5.17 3.75
SOLARVOX 20. 10 watts RMS per PIONEER PL61 with base and cover 18033 124-º5
channel 4395 26 95 THORENS TD125 Mk. II Chassis
Audlom 10P 5.62 4.10
77.00 8295 Audlom 12P 14.30 1040
SOLARVOX 30. 15 watts RMS per THORENS TD125AB 100.04 7250
channel 5105 3595 Audlom 15P 23.10 1050
THORENS TD 125AB Mk. II with Audlom 18P 39.27 27-98
SOLARVOX MA801 2 o 8 watts TP arm
16 118.05 9550
RMS plue MATRIX 4 channel 42.30 2975 THORENS TD 160/c Including base
Audlom 100 40 watts din. 1320 9.89
SOLARVOX MA813 2 x 18 watts ARU 172 4.95 3.89
and cover 65.04 53.50 Axent 100 7.59 5M
RMS 56.62 4295
TANDBERG TA300 Teak 84-82 67 95 Midax 650 1496 989
TANDBERG TA300M Teak
The following Turntables are complete with Attenuator 4.10 298
98-24 79.95 base, plinth, cover and cartridge. Fully
WHARFEDALE Linton amplifier 71.50 50 95 Crossover network XO/950 8.55 5-98
wired and ready for use. WHARFEDALE8 In. Bronze/RS/DD 4-44 3.20
All take both ceramic and magnetic cartridges. McDONALD MP60 TPD2
TUNER/AMPLIFIERS Super 8/RS/DD 7.85 8.79
with 6600 24 26 15 50 Super 10/RS/DD 13.11 9.45
AKAI AAO030 130-54 9695 McDONALD MP60 TPDI
AKAI AA80813 178.07 131 95 de luxe with 0000 26 60 16 95
AKAI AS8100S Quadraphonic 243.85 161.95 McDONALD MPSIO TPD CARTRIDGES
AKAI AA8500 23398 166 95 automatic with 0960 29 19 1795 ADC 10E Mk. IV Sp. Price 15.95
AKAI 6300 129-21 74 95 McDONALD HT70 TPD AUDIO TECHNICA AT 66 6.17 3.30
AUTOMATIC RADIO CHX 9012 with G800 3241 20 95 CONNOISSEUR SCU1 5.78 4.75
AM/FM: MPX stereo tuner/ampli- GARRARD 2025 TC with GOLDRING 0850 6.78 2.95
fier with built-in stereo cassette Sonotone 9TAHC ceramic Sp. price 1210 GOLDRING 0800 Sp. price 3.75
recorder 107.25 4995 GARRARD SP25 Mk. III GOLDRING G800E Sp. price 9.50
GOODMANS Module 80, 35w. RMS 87.55 e0 25 with G800 Sp. Price 1675 GOLDRING G800 Super E Sp. price 12.50
Module 80 Compact 158-16 11250 GARRARD AP76 with 0800 GOLDRING G820 11-00 7.50
Module 90 11204 75 75 cartridge Sp. Price 25 95 GOLDRING G820E 1850 11.40
Module 110 FM/MW/LW/SW/ GOLDRING ßL72 with MOO GOLDRING G820 Super E 22-00 1520
100w. RMS 13086 8850 cartridge Sp. Price 3395 EMPIRE 1000ZE/X 5887 3795
GOODMANS Module 110, Compact 230-65 16995 GOLDRING ßL76 with 0900 EMPIRE 999VE/X 42.05 26 95
JVC Nivico 4MM 1000 Quadraphonic 161.15 128 95 cartridge Sp. Price 41 95 EMPIRE 999TE/X 24.733 16 25
4VR 1006 Quadraphonic with GOODMANS TD100 with EMPIRE 999SE/X 10.98 1205
CD4 demodulator 22935 18350 Gt.00E 7109 49 95 EMPIRE 999E/X 15.48 1030
VR 5501 AM/FM 10835 85 95 JVC Nivico SRP 473 with Nivico EMPIRE 909E/X 1210 7 05
VR 5S21L AM/FM and SEA 172.70 13895 magnetic cartridge 7150 5895 EMPIRE 90EE/X 9.41 6.20
4VR 5414 Quadraphonic SEA 229.35 18350 LEAK Delta deck with SHURE M3D 5.81 3.60
4VR 5445 Quadraphonic SEA 30800 24550 Shure Cartridge 65 07 49 95 SHURE M44-G 7.91 4.60
KYOTO 1000 AM/FM Tuner/Ampli- PHILIPS GA407 with 0P498 SHURE M44-7 7.52 4'20
Rer with built In Stereo Cassette mag. Cartridge 4500 3495 SHURE M -44C 7.52 4 60
Recorder. Complete with two PHILIPS GA212 Electronic SHURE M44E 8.18 4.60
speakers end two microphones 79.90 57.95 with GP400 cartridge 84.95 5095 SHURE M55E 9.24 S-30
LEAK Delta 75 AM/FM MPX 16383 11295 THORENS 160C with Ortofon SHURE M75G 14.00 7.90
PHILIPS RH 702 9038 5995 MISE Super cartridge 92 54 7695 SHURE M75-6 (S) 818 4.95
PHILIPS RH 720 20241 154 95 WHARFEDALE Linton with SHURE M75 -B 1295 7.10
PIONEER SX 424 AM/FM/MPX 116.70 79 95 Shure Cartridge 3511 25 95 SHURE M75EJ 1488 0.25
PIONEER SX525 AM/FM/MPX 148.38 101 95 SHURE M75ED 1810 10.10
PIONEER SX626 AM/FM/MPX 203.21 138.95 SHURE M75EJ95G Sp. Price 12.15
PIONEER SX727 AM/FM/MPX 244.63 168 95 SPEAKERS SHURE M91ED 1810 5.50
PIONEER SX828 AM/FM/MPX 313-74 216.95 AMSTRAD 138 (pair) Teak 28 60 13.65 SHURE V15-11 37.52 24.98
PIONEER QX 4000 Quadraphonic B and W Model 70 17545 125.115 SHURE V76-Mk. III 39.00 28.98
AM/FM/MPX 238.50 144 95 B and W DM2 65 89 4695 SONOTONE 9TAHC Dlam/Saph 3.58 1.36
PIONEER OX 8000A Quadraphonic B and W DM4 4675 3595 Starred cartridges above are ceramic -all others
AM/FM/MPX 339.23 233.95 B and W 05 (pair) 55 99 4195 ere magnetic.

214

www.americanradiohistory.com
 minggilitc

COMET for
OVER 1000 ITEMS ALWAYS IN STOCK after -Salas Service
THROUGHOUT THE U.K.
All items brand new and fully Guaranteed
and backed by after -sales service
Service Departments
er. Edinburgh. roc... Geode. Dxhed r
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- latest models in manufacturers' sealed carteas

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Teetide. Wigan.

Rec. Retail Comet Rec. Retail Comet

Rec. Retail Comet Price Price Price
Price Price Price £
£ p £ p BLANK TAPES £ p £ p TAPE RECORDERS -continued p £ p
BASES AND COVERS ARAI CR8DISS Quadraphonic 149.88 10995
CONNOISSEUR Plinth BD1 5.28 4-30 SCOTCH DYNARANGE CASSETTES AKAI CR81 102.89 75 95
3.96 3.20 COO 0.77 641 84.10 8195
CONNOISSEUR Cover C90 1.08 9.55 AKAI CR81D
CONNOISSEUR P.U. Mount Board 0.88 9.70 AKAI CR81 T8-trackcartridgeStereo
3.56 2-70 C120 1.63 0.55 10795
GARRARD WB1 Base recorder end tuner amplifier 145 65
GARRARD WB4 Base 5.28 3.90 SCOTCH HIGH ENERGY COBALT CASSETTES BSR McDONALD TD8S 8 -track
3.47 2.60 C60 1.20 111-75
22'27 14.95
GARRARD SPC1 Cover 1-54 1.44 play back deck
GARRARD SPC4 Cover 4.13 3.00 C90 FERGUSON 3258 4 -track 66 85 4701
S SCOTCH CASSETTE HEAD FERROGRAPH 702/704 Dolby 267.30 22995
CLEANER 081 0.40 278.30 235'95
fitGARRARD SP25, SL55, SL65B FERROGRAPH 702H Dolby
and 3500 Sp. Price 2.54 SCOTCH Low Noise 8 -TRACK FERROGRAPH 722/724 Dolby 305.80 258 95
Special offer of base end cover to BLANK CARTRIDGES FERROGRAPH 722H Dolby 318.80 264.95
Sp. Price 3-S6 80 mina 1.98 1.20 220.00 14795
fit McDONALD MP60 and 610
Sp. Price 9.75 FERROGRAPH 7021704
GOLDRING Plinth 75 12.87 8.99 MAGCAM 8-track 80 mins. FERROGRAPH 722/724 258.50 164"95
GOLDRING Plinth 72 11'22 7.40 SCOTCH HI-FI DYNARANGE SPOOLED TAPES FIDELITY Braemar 4 -track 3264 18'50
4.62 3.20 V L.P. 900 2.02 1-25
GOLDRING Covers for 72P 2.37 1.45 GROSVENOR RP 9008 -track record,
Cover for 75P De Luxe 5.28 3.64 51' L.P. 1200 play-back deck 51.15 3695
7-26 5.00 772 L.P. 1800
3.18 1.99 92.87 7295
Cover for 78p GRUNDIG TK 147 (4 -track auto)
Cover for 85P 7'28 5'72 SCOTCH HI-FI DYNARANGE DOUBLE PLAY GRUNDIG TK 148 (4-track auto
9.35 6.50 5' D.P. 1200 2.50 1S5 8989 5365
McDONALD Plinth for 710/810 51' D.P. 1800 3-41 2.15 2 speed)
McDONALD Cover for 710/810 4.40 2.95 GRUNDIG TK 248 4-track stereo deck 126.78 9495
THORENS TX 25 (for TD125AB) 8.25 S-41 7 D.P. 2400 4.37 2.75
GRUNDIG TK 3200 HI-FI (Battery) 13515 9995
THORENS 7X11 Cover 4'18 3'46 Tapes, cassettes and 81 cartridges, 1-9 items 5p MARCONI 4248 4 -track, 2 speed 4969 3595
SME Plinth System 2000 with motor- per order. Packs of ten post free. PHILIPS 4307 4-track 4740 3395
board 3t HI-FI STEREO SYSTEMS-COMPLETE PHILIPS 4308 De Luxe 4-track 55.92 3995
MOTORBOARDS only 5.51 0.72 BUSH A1005 66.25 45'95 PHILIPS 44164 -track stereo recorder 137.46 9995
SME P1 Spacer 0.92 9.70 BUSH 1006 with radio 8906 17-95 PHILIPS 4418 4 -track stereo 189.59 137 95
TUNERS DANSETTE 4005 67.73 47.95 TANDBERG 3321X 2 -track stereo
AKAI AT550 AM/FM/k7PX/FET 84.10 6195
I

DANSETTE 4020 45.50 2995 deck (teak) 137.38 114.95

AKAI AT580 AM/FM/MPX/MOS FET 131.09 911.95 SOUND 813 63-95 4$-aS
24.95
DECCA TANDBERG 3341X 4 -track stereo
AMSTRAD Multiplex 3000 FM 37.90 DECCA COMPACT 2 with radio 96-03 7S -9S
deck (teak) 137.38 114.95
DULCI FMT 7 FM 23-16 14.90 DECCA COMPACT 3 with radio 127.09 99-95 TANDBERG 6041X 4-track stereo 18782 153.95
JVC Nlvico MCI V5E/VT500 AM/FM 8250 9595 DECCA 403 54-45 42-95 TANDBERG 9021X 2 -track stereo
VT 700 126.50 101.50 FERGUSON 3450 B with Radio deck (teak) 230 19695
MCT V7E AM/FM 11525 M 9S (new Model) 75.40 59.95 TANDBERG 9041X 4 -track stereo
LEAK Delta FM 74.43 52.95 FERGUSON 3451 B with Radio deck (teak) 23600 198 95
LEAK Delta AM/FM 83'79 62'25 (new Model) 101.50 79 95
THORPE GRENVILLE TD1458-track
METROSOUND FMS 20 Mk. ll 5445 38 95 FERGUSON 3454 39-95 3065 play back deck 2028 13 50
METROSOUND FMS 40 5610 40 62 FIDELITY UAt Music Master with
PHILIPS RH 690 45.66 3350 Radio 94.81 8795 TAPE RECORDERS (CASSETTE)
PHILIPS RH 621 103.06 79.90 FIDELITY UA2 Music Master 41-23 2895 AKAI CS3SD tape deck 75.13 52.95
PIONEER TX500A AM/FM 79.72 5395 FIDELITY UA3 Incl. stereo radio 59-73 4395 ARAI CS35 Stereo Incl. Speakers 105.71 77.99
PIONEER 7X600 AM/FM 110.39 7595 FIDELITY Stereo Nine Sp. Price 22-95 AKAI GXC 400 tape deck 89.74 65.95
PIONEER 7X6200 14.60 65-5 G.E.C. 2810 74-89 5895 AKAI GXC 40 105.71 7595
PIONEER 7X7100 111-10 7695 GROSVENOR MPX 8400 AM/FM/ AKAI GXC 401 recorder, tuner!
PIONEER 7X8100 150-70 103 95 MPX Tuner/Amplifier, magnetic amplifier 15740 116-95
PIONEER 7X9100 204.60 139.95 Input, built-in 8 -track cartridge AKAI GXC 45D tape deck 112-28 83'95
RANK ROTEL 320 55-91 39-05 player with speakers 6575 39-95 AKAI GXC 46 Dolby tape recorder 143.30 10695
RANK ROTEL 620 87-86 62'95 HMV 2451 115-70 09 95 ARAI GXC 460 Dolby tape deck 131.09 96-95
ROGERS RAVENSBOURNE HMV 2452 8257 48-95 AKAI GXC 65D Dolby auto -reverse
SERIES II (cased) 61.05 4750 HMV 2455 16590 12995 deck 145.18 10705
ROGERS RAVENSBROOK SERIES I T.T. KB1025 with 662 speakers 45.65 35 95 BUSH TP 66 Battery/Mains 26-70 20-95
II (cased) 46.75 3695 I.T.T. KB2250 with 659 speakers and FERGUSON 3253 (mains) 41 -15 26.95
SINCLAIR 2000 4244 2995 radio 136-83 105-95 FERGUSON 3256 (mains) ......- 3661 23-95
3000 42.44 2995 PHILIPS 808 99-53 72.115 FERGUSON 3257 53-45 34-45
All above Tuners are complete with MPX Stereo PHILIPS 825 46-92 34'95 FERGUSON 3257/7 speakers for
Decoder except where starred. - PHILIPS 826 71.09 49-95 above 15-20 11.50
HEADPHONES PHILIPS 835 with radio 65.86 46.59 GEC CR200 AM/FM Cassette/Radio,
AKG 8180 30'110 11'711 PHILIPS 836 with radio 9005 6595 Battery/Mains with slide controls Sp. Price 34.44
AKG K60 16.50 9.72 ULTRA 6027 54.55 4295 GRUNDIG
AKG 100 11'80 6'1111
ULTRA 6028 5885 4795 HARVARD CÉ1 e Cas10 sette/AM/FM
AMSTRAD HPS5A 8'25 4'311 ULTRA 6450 B (new model) with Radio (battery/mains) Sp. Price 2295
HPS6A with volume control 11-77 7.45 radio 75.40 5895 JVC NivIco 9420 LS wlih AM/FM
KOSS HV1 22'00 17'72 ULTRA 6451 75.40 5695 radio, battery/mains 57-84 39.95
KOSS ESP -9 Electrostatic 7590 5625 ULTRA 6455 39.20 2995 JVC Nivico 1710 Radio/Cassette,
KOSS ESP -6 Electrostatic 49.50 39'50 I
ULTRA 6454 36.80 2895 AM/FM Sp. Price 37.95
KOSS K2 plus 2 Quadrafone 4950 39.95 PHILIPS 2202/2203 22.59 16.95
TAPE RECORDERS 28.25 21-95
KOSS PRO 5 L/C 93.00 Y8'50 ARAI 1121L 9387 66-95 PHILIPS 2204 battery/mains
KOSS PRO-4AA 30'60 2325 I
ARAI 4000 OS 93.50 6995 PHILIPS 2405 Stereo with 2 RH401L/S 67.78 5195
KOSS KO -727B 1600 13-75 16830 123 95 PHILIPS 3302 20.24 1495
KOSS K-747 22-00 1650 AKAI X201D PHILIPS N2510 stereo deck, DNL
AKAI X1810 21518 159.95 9595
KOSS 1 .70 850 215-18 159.95 Cr02 125.00
1050 AKAI GX221D 10:95
KOSS KB 13-75
AKAI GX19001) 224.57 16695AKAI PIONEER CT 4141 Dolby Deck 158-3765.80

KOSS K6/LC (with volume control) 15-40 16.75 PYE 9116 Stereo 95
GX370D 328-95 244.95 65 80
KOSS K6/LC Quadrafone 24'09 14.59 ARAI CRBOD 8-track stereo tape deck 79.90 63.95 PYE 9140 41 95
PIONEER SE 0 3.86 19'25 AKAI CR80 8 -track stereo recorder 11702 59.55 WHARFEDALE Dolby DC9 Mk. 11 111.41 82.50
PIONEER SE 30A 13-86 1.25
FREE Technical Advisory Service. If in doubt ask usi Price list on request.
PIONEER SEL 20A 8.67 5.55
PIONEER SEL 20 11.58 7.59 cheques, Money
PIONEER SEL 40 19.17 12.51 Comet guarantees that all prices quoted are genuine. All offers subject to availability. Make
SOUND MD806 7.15 3.10 Orders payable to 'COMET'. and Insurance. all other goods sent
WHARFEDALE DD1 1375 9.75 ORDERING INSTRUCTIONS cartridges -add 22p for postage. packingDelivery.
vla Securicor Delivery-add £2.15 to each complete order for Seruricor

cromsr
WHARFEDALE Isodynamie 21 95 le 50

HIGH FIDELITY DISCOUNT WAREHOUSES

BIRMINGHAM: Dept. P.W., Heeley Road, Sally Oak, B29 BEY. Tel; 02f-472 6181 SECURLOvICE
BIRMINGHAM: Dept. P.W., Tivoli Shopping Centre, 1570-1572 Coventry Road, Yardley B26 1BJ. Tel: 02f-706 0684
LONDON, DAGENHAM: Dept. P.W., !Wilhelm Road South, Dagenham, RMIO 8ST. Tel: 01-595 5111 ifi,,,k ftl
EDINBURGH: Dept. P.W., 1 Newhaven Road, EH6 5QX. Tel: 031-554 4454 (9 lines)
HULL: Dept, P.W., Reservoir Road, Clough Road, HUI 700. Tel: 0482 46441 (6 lines) i+-
LEEDS: Dept. P.W., 78 Armley Road, LS12 2EF. Tel: 053240551
SHEFFIELD: Dept. P.W., The MITI, 1 Lesley Road, Malin Bridge, 56 4TN. Tel: 0742 34172116 BLOURIOOR .stew n mars
STOCKTON: Dept. P.W., Teesway, Portrack Lane, Teesside. TSI8 2RH. Tel: 66132/65215 Sr,uao eeb.vYl
(Add 1115 only for
ROCHDALE: Dept. P.W., Corner of Well l'th'Lane and Queenswey. Tel: 50606 ALL 60001 FULLY INWeto AGAINST
LEICESTER: Dept. P.W., Syston Street. Tel: 0533 52236 LOU OR DAMAO9 WHILST IN 111ANan
WIGAN: Dept. P.W., Wharl Mill, Princess Street, WN3 4EZ. Tel: 094234741
LONDON, HACKBRIDGE (Nr. Croydon): Dept. P,W., 190 London Road, Hackbridge, Wellington, Surrey Tel: 01-669 027110106
OPEN DAILY TO THE
For Phone Order Tel: 01-643 8989
SUNDERLAND: Dept. P.W., 4-7 St. Thomas Street, Sunderland, SR1 1HR. Tel: Sunderland 59993 PUBLIC FROM:
RENFREW: Dept. P.W., Blythswood Trading Estate, Argyle Avenue, Renfrew, RA4 9EL. Tel: 0418865731 gam-11pm Monday
JARROW: Dept. P.W., 50/64 Ellison Street, Jarrow, NE32 MAT. Tel: 0632 892211 9am-1 pm Tuesday
LONDON, HAYES: Dept. P.W., Silverdale Road, Pump Lane, Hayes. Tel: 0f-573 1841 9am-8pm Wednesday
SANDIACRE: Dept. P.W., 121 Town Street, Sandiacre, Nottingham, NG10 512W. Tel: Sandiacre 6116 Sam-gpm Thursday
EASTLEIGH: Dept. P.W., Chlckenhall Lane, Eastleigh, S05 5ZQ. Tel: Eastleigh 4722 9am-8pm Friday
LONDON, ROCHESTER: Dept. P.W., Maldstone Road, Rochester. Tel: Medway 49171 Sam-5.30pm Saturday
GRIMSBY: Dept. P.W., 389 Victoria Street, Grimsby DN31 1ER. Tel: 0472 59623
NORWICH: Dept. P.W., Roundtree Way, Norwich NOR 94P. Tel: 0603 411831
215

www.americanradiohistory.com
 FORMATIVE HABITS
DURING the first 18 years of human life a great many
natural developments take place which perhaps we
take for granted. One of these is the shrugging off of
juvenile behaviour characteristics and the adoption of a Mobile rally diary
mature outlook to face the rigours of a competitive world. June 17-Amateur Radio Mobile
When applied to a technical art such as broadcast Society Rally, R.A.F. Cosford,
entertainment, not only do programme standards alter, Shropshire. Details from W. S.
but also the medium by which they are conveyed. The Barwick, 34 Malvern Rd., London.
obvious examples that spring to mind are the progressions N.8.
through 405 -line, 625 -line, and colour television for one; June 24-West of England
acoustic gramophones, mono discs, 2-channel stereo and (Bristol City and County RSGB
quadraphonic sound for another. In spite of a mixture of Group) Mobile Rally at Longleat.
pessimism, cautiousness, apathy, or just plain rejection, Further details of this popular
developments in the methods and standards of technical rally can be obtained by dropping
achievement still win through. a line to A. H. Williams, G8CKJ,
But there is still a very interesting factor; that is a great 58 Britannia Road, Kingswood,
reluctance, especially in the U.K., to shake off some of those Bristol.
formative habits. We still have 405 -lines, mono discs (often July 1-South Shields and District
forced to undergo processing to stereo status), and of Amateur Radio Club's rally will
more topical concern, medium wave broadcasting. Why? be at Redwell School, Prince
Or equally, why not? The very organisation that has been Edward Road, South Shields.
trying to convert us to v.h.f./f.m. for the past 18 years is July 8-Cornish Rally at Trevi-
still promoting broadcasting on m.w./l.w. Even more glass County Secondary School,
interesting-the IBA are now doing likewise. Why? Newquay, Cornwall.
Have you bought or built an f.m.-only tuner in the light of July 8-The Worcester and Dis-
the advice about improved reception of BBC programmes, trict Amateur Radio Club are
only to find that you cannot receive the programmes that go organising the Upton -on -Severn
out on a.m. only? Do you also find that reception in cars Mobile Rally and further details
via f.m. is very difficult because of interference? Are you can be obtained from B. A. Jones,
finding station separation on the medium wave more G8ASO, 12 Woodside Road, Lark -

difficult? It is truly amazing that in spite of "progress" our hill, Worcester, WR5 2EG.
broadcasting system is still bugged on occasions by major July 22-Anglian Mobile Rally
reception problems. (See letters on page 261.) will be held at the Suffolk Show -
It is interesting to note that the BBC are experimenting ground Bucklesham Road,
with concurrent television and stereo radio programme Ipswich. Readers can obtain fur-
material. Let's have more! Experiments are also going ther information by contacting C.
ahead on broadcasting quadraphonic sound, but we have J. Wantling, G3TNE, 15 Melplash
not heard them yet. Road, Ipswich, Suffolk, IP3 8QJ.
In the meantime we will go on promoting v.h.f./f.m., Telephone Ipswich 75241.
especially for constructors. Mr. Ainslie's recent article was July 22-Southdown Rally at Pole -

typically a popular project. Mr. Rayer describes a special gate, Wilmington.

receiver in this issue, that enables the experimenter to August 5-Radio Society of Great
extend reception outside the usual 88-108MHz limits of a Britain Mobile Rally at Woburn
conventional dial. Future issues will provide state-of-the-art Abbey, Beds.
circuits of f.m. stereo. But we will not forget a.m. On the August 12-The Derby and Dis-
contrary we shall do all we can to provide constructors with trict Amateur Radio Society are
limited experience some simple circuits to build, and at low holding their 1973 rally at the
cost too; more details about this next month. usual venue i.e. Rykneld School,
M. A. COLWELL-Editor Bedford Street, Derby. There's
ample inside accommodation if it
rains and plenty of parking space
The August issue on sale 6th July, will include for cars. In addition, there will be
our new all -transistor oscilloscope specially plenty of attractions for the XYL's
designed for students, experimenters and con- and harmonics. If you want to
structors who want reliable performance coupled know more, send a s.a.e. to Fred
with simple construction. We shall also have a Ward, G2CVV, 5 Uplands Avenue,
communications receiver and details of a new Littleover, Derby, DE3 7GE.
Datacard scheme commencing in the autumn. August 12-Torbay Annual
Our autumn issues are being planned as the best Mobile Rally will be held at New-
yet for new projects and ideas on home enter- ton Abbot Rugby Club ground.
tainment. We would hate the idea of you missing There will be talk -in stations, the
them, so order your regular copies of Practical usual stands and various competi-
Wireless now. Further details on page 239. tions. The contact for further gen
is L. H. Webber, G3GDW, 43 Lime
Tree Walk, Newton Abbot, Devon.
216
 NEWS... NEWS... NEWS...
MOS i.c.'s and their Applications An Aussie `First'
rHE latest book published by Mullard Ltd. is entitled "MOS Inte- RON Wilkinson, VK3AKC is
grated Circuits and their Applications". It provides the reader the first man in Australia
with an introduction to these devices and should be ideal reading to send a radio signal to
for designers unfamiliar with them and for electronic engineering America via the moon. He used
students. the frequency of 1296MHz and
The construction, manufacture and characteristics of MOS i.c.'s are the signal was received by the
covered and the ways in which Crawford Hills UHF Group U.S.A.
they can be used are fully
explained.
A short description of the opera-
tion of the devices is followed by
the explanation of the manufac-
turing processes of the various
types of MOS i.c.'s. The static
characteristics of the MOS tran-
sistor are examined and a descrip-
tion given of the static inverter
which forms the basis of the
gating elements used in MOS
logic devices.
Switching characteristics are
discussed and the main MOS
static and dynamic logic circuits
are examined.
Interface circuits are given and
input/output protection devices
described.
The final chapter deals with
typical logic applications in
which MOS i.c.'s can be used
advantageously. The aerial used: a 2011. parabolic dish.
The book, cloth bound with 176
pages costs £2 -and is obtainable
from leading booksellers. Circular aerials for VHF
EMI has been awarded contracts to provide the Independent Broad -
Interface '73 casting Authority with transmitting aerial systems for Britain's
TEXAS Instruments will first commercial radio stations.
again be holding their Altogether six systems are being supplied and they will cover five
annual Seminar at the major cities throughout the country including London, Birmingham,
'Talk of the Town' in London. It Glasgow and Manchester. Transmissions from the new stations are
will be entitled "Interface 73" expected to commence towards the end of 1973.
and will run for 3 days-June 12, Two v.h.f. aerials have been
13 and 14. The same programme specified for London and Birming-
will be repeated each day. ham, which will be the first of
In addition to presentations on their type in this country, utilising
Optoelectronics, Memories and circular polarisation techniques.
Power Devices etc. Texas Instru- These techniques are used exten-
ments are expecting to make sively in the United States to
important policy statements on give improved reception for
the Digital I.C. market. transistor and car radios.
The aerial system for London,
which is 60ft. high, will be
Audio Fair '73 installed on the top of the 500ft.
television tower at the IBA Croy-
ATES are announced for don transmitting station. This
D the 1973 International
Audio Festival and Fair
and, for the first time since the
aerial will transmit two pro-
grammes to the London area. The
second v.h.f. system will be
exhibition moved to Olympia in mounted on the 1000ft. mast at
1969, it is to be open on a Sun- the Lichfield transmitting station,
day. Dates are October 23 to 28. near Birmingham.
217
 ^^ FG.RAYER

receiver
THs usual VHF' recei' cr has a single VHF band
covering those frequencies used' for VHF
broadcasting. The actual band varies with
different receivers, but is often about 88-108MHz or
so. This is usually obtained with fixed coils and a
small ganged variable capacitor in conjunction with
fixed capacitors and trimmers.
Experiments with a view to increasing coverage
beyond that of popular VHF receivers show that the
range can be extended in the HF direction by CIRCUIT
eliminating the parallel fixed capacitors and Fig. 1 is the circuit of the receiver, the rod aerial
trimmers in the tuning circuits, as would be expected. or feeder being taken to the primary of L1, which
For a reasonable inductance to capacitance ratio, is tuned by VC1. L2 is the oscillator coil, capacitor
tuning values of about 25pF are about the largest VC2 having a ball drive and dial for tuning. Ll and
useable, but it is found that provided the layout L2 are miniature plug-in coils, for changing bands.
gives the shortest possible leads, miniature plug-in Trl is the dual-gate FET mixer, output from the
coils are satisfactory, allowing extended coverage. drain going to IFT1. Transistors Tr3, Tr4 and Try
As trimmers would curtail coverage in the HF are the three 10.7MHz IF amplifiers, with double -
direction, and interchangeable coils are envisaged, tuned IF transformers. C8 and C11 are necessary to
separate tuning capacitors become almost essential. neutralise these stages. IFT4 is a ratio discriminator
This eliminates ganging or alignment difficulties in transformer with the matched diodes D1 and D2 the
this part of the receiver and works out quite satis- audio output being taken via R19 from the tertiary
factorily because only the oscillator requires a reduc- winding.
tion drive. The second tuning control is merely VR1 is the audio volume control feeding a 3 -stage
peaked for best results. amplifier. A 212in. speaker is incorporated for port-
To facilitate alignment only two tuned circuits are able use, but the output jack allows a larger speaker
used and since a single pair of plug-in coils will cover or headphones to be plugged in.
a band larger than the usual VHF range there is no The mixer and oscillator stages, with associated
need to fit other coils if not wanted. components, are built on a metal chassis but the IF
The receiver intermediate frequency is 10.7MHz, and AF amplifiers are built as separate units on
so the second channel occurs at 21.4MHz from the insulated boards.
wanted tuning frequency. As the tuned circuits have
separate controls, some signals can thus be received
at two positions of the oscillator tuning, depending
on whether the oscillator frequency is 10.7MHz
above or below the wanted signal. This is an effect CHASSIS AND PANEL
which is unavoidable, if the advantage of separate The chassis is 8 x 4in. and is a universal chassis
tuning capacitors is to be retained, but it is not too flanged member. For the case described, the panel
important provided it is understood that this effect is flat aluminium, 8 x Sin. Fig. 2 shows the underside
can arise. of the chassis.
In view of this, the bands given below are those VC1 is mounted centrally and 14in. clear of the
of the oscillator coverage: chassis. The holder for L1 is placed so that the leads
Band 1 34- 55MHz from pins 1 and 6 are as short as possible, as shown.
Band 2 45- 72MHz VC2 is mounted on a metal bracket and is set
Band 3 82--140MHz back to accommodate the ball drive. The holder for
Band 4 110-180MHz L2 must also be placed to allow very short leads to
For general VHF use, Band 3 coils will be most VC2. The ball drive requires a 34in. or lin. hole in
suitable, the reception coverage then being approxi- the panel and its lug is fixed with a 6BA bolt. VC2
mately 72-130MHz, with the oscillator HF of the and the drive need to be lined up to give a smooth
signal frequency. free movement. The listed drive has a flange and
218
* components list
o
0ìí)
Resistors
R1 100k12 R13 68012 R25 471(12 óóó
R2 2ßk12 R14 11d2 R26 33kd2
R3 100k12 R15 331(12 R27 47kL2
R4 1k12 R16 5.6kí2 R28 12kL2
R5 10k12 R17 ík12 R29 27k12
R6 101(12 R18 68012 R30 68012
o
R7 33k12 R19 10012 R31 22k12 5` r`
R8 5.6k12 R20 68012 R32 3912 5º{, ú
o
R9 68012 R21 68012 R33 5.6kí2
R10 11d2 R22 4.7k12 R34 470k12
R11 33k12 R23 4.7k12 VR1 221d2 log.
R12 5.61(12 R24 5.61(12 pot. with switch St 12111111Leallikleiel
All 10%W except R31 and R32, 5°

Capacitors
Cl 22pF C11 5pF C21 2µF 6V
C2 1000pF C12 5000pF C22 001feF
C3 5pF C13 5000pF C23 2µF 6V
C4 5pF C14 5000pF C24 100µF 12V
C5 5000pF C15 5000pF C25 2µF 6V
C6 0.01µF C16 5000pF C26 60¡eF 6V N
C7 5000pF C17 5000pF C27 100/eF 12V z
M
C8 5pF C18 330pF
C9 5000pF C19 330pF
C10 5000pF C20 001µF
VC1 and VC2 25pF variable (Jackson C804)

Semiconductors
Tri 3N141 Tr4 OC170 Tri 00810
Tr2 BF200 Tr5 OC170 Tr8i9 0081
Tr3 OC170 Tr6 OC71 0112 0A79

Miscellaneous
IFT1/2/3, (Denco IFT15). IFT4, (Denco RDT2). T1,
(Home Radio TR64). T2, (Home Radio TR85A).
Chassis, 8 x 4in. Universal chassis flanged member,
panel 8 x 5in. (Home Radio). Valveholders B9A(2).
Ball drive, (Jackson 45111F). Dial 21in. dia. (Bulgin).
Veroboard 0.151n. matrix, and pins. Knobs. Coaxial
socket. Speaker312, 211n. dia. Jack socket(switched).
Ll/2, see text.
ALIGNMENT GENERATOR
R1 22k1) R3 1k12 R5 5.6k0
R2 5.61(12 R4 221(12

Cl 5000pF C3 0-01f,F C5 22pF

C2 1000pF C4 47pF

Miscellaneous
Tri, 0071. Tr2, AF117. T1, (Home Radio TR64).
L1, (Denco 'Blue' Range 4, Valve type). S1/2
toggle, on/off. Chassis, 5 x 2in. universal chassis
flanged member (Home Radio). Veroboard, pins.

the metal dial can be fixed with two very short 8BA
bolts run into the tapped holes.
Wiring for Tr2 is shown in Fig. 2. Very short leads
are essential to C4 and CS. The shield lead Sh is not
connected. The oscillator may be tested by connect-
ing a 9V battery to chassis and negative lead (observe 3
the polarity shown). If this stage is oscillating,
battery current, as indicated by a meter in one 251
battery lead, will change when VC2 is shorted. If s eta
this stage does not oscillate, the receiver cannot work il.
at all. A transistor of doubtful efficiency may oscillate On,f
at the lower frequencies but not in the 150-180MHz
region. So the test can be made with all coils, and for 1000
all positions of VC2.
219

www.americanradiohistory.com
 Aerial
Output jack socket

Fig. 2: Layout underneath the

chassis with the tuned oscillator
stage at the right. The mixer stage
board (Fig. 3)1s in the centre with
its associated tuned circuit. The
speaker is Interconnected with the
headphone jack socket mounted on
the rear apron of the chassis.

MC

MIXER BOARD be spread with a sharpened matchstick, but should

This board is 178
not be touched with a metal or plastic tool, or the
x 34in. of 0.15in. matrix plain
fingers. Solder source and drain leads. Then while
Veroboard, wired as in Fig. 3. A 6BA bolt, with extra holding iron and solder in contact with the lead from
nuts, allows the board to be locked to the metal Cl/R1, solder gl. In the same way, hold the iron and
chassis, with enough clearance to avoid any short solder against the lead from R3, and solder g2. When
circuits. This bolt forms the earth return. the resistors are soldered to provide an external
The leads of Cl and C3 can be left projecting, to circuit from gl and g2 to the source, the transistor
solder to VC1 and VC2. Also fit a pin or projecting is protected and the wire clip is removed. If gl or
lead for the negative connection, and a wire which g2 have to be unsoldered from R1 or R3, or these
can pass down through the board and chassis, to resistors have to be unsoldered, the transistor leads
reach pin 3 of IFT1 on the IF amplifier. should first be bound with thin wire.
Transistor Trl should be supplied with a shorting The board is fixed as in Fig. 2, and external con-
clip on its leads, and this must not be removed until nections are made. The co-axial aerial socket and
the transistor has been soldered in place. First wire output socket are fixed to the rear flange of the
the board as in Fig. 3, omitting Trl. Solder on the chassis so that the receiver can be tested out of its
wires which will go to gate 1, gate 2, source and case.
drain, and cut them to length and tin them. Trl is
then inserted with its wires as shown. The leads can
-ve IF AMPLIFIER
This is assembled on a 512 x 134in. board as in
Pin 3 Fig. 4. First mark and drill holes for the IFT's and
04_ R1 I+ .-{ R 2 }-. o o o IFT1 for the two 12in. 6BA bolts. These, with additional
nuts, form the chassis return and hold the board
1. o4,-1 H fó
o91
os®d!
.¡ C2
92
0 0 0
R3
0 .i3I.- o
VC2
the metal chassis.
Leads should be short and direct, and insulated
sleeving is put on where necessary. If loin. lengths
of small diameter sleeving are put on the transistor
o o o o o .{ C
leads this will prevent shorts and hold the transistors
at a suitable height, while also identifying the wires.
Note that all the IFT screening cans are earthed.
Pin 6 L1 As the IFT's are prealigned, unnecessary disturbance
of the cores is better avoided. When wiring D1 and
D2, note that these may have a black ring to show
positive. Polarity must be correct as a DC voltage
is produced across C21.
1 o -C2- o o o o -C3--+-- Run a lead from pin 3 of IFT1 to a pin or wire,
Cl o s d
MC
O o o o O
so that the wire from Trl can be soldered on later.
A black lead, to go to battery negative, is soldered
R3-
-R1- 2 R2 -/ o
to R18, Fig. 4. A lead from R19 is provided, and will
pass through the chassis to VR1.
If this section is tested with the board separate
from the receiver, do not run a signal generator or
other lead from pin 3 of IFT1 near the other IFT's
-ve or circuits, or instability may be caused which would
not be present when the amplifier is fixed to the
Fig. 3: Both sides ofthe mixer stage board. chassis.
220
 View of the underside of the FM receiver which should be compared with Fig. 2.

o
O
0
.R18}-
0 0

000000000000000
0H R15
o 0
r0-1 o 0
R13
0 0-{
1~D o
R11

0
)-6o
o-1
O O
0

O
0
R9
O
r
os
O
-1

O
R7
o

O
0
o
1--4,

0
o
o
0

o
O

M'yor
O
0

o
0

+o o O C
<ID

o 0
R19
ir
°
i
He
o
IFT4

o
IFT3

o
i
o

o
_eh

V
Te T
_I o
V o
o
IFT2 IFT 1

o
o
o
o
0 0
N
o o
10 f O 1
0 lr
Ttf
R2f o
o o
o
o
o
o

n
o
o
o
O
V D
o
0
O

o
O

O
O

O
V
N
K
O

o O21
O O

O
O

O
Ú m
O

O
O

O
o
o

0(/0 o 2 C2 o o o 0 0 o
o o
o¡TooaTooTT
O O O
0 U
O 0 0 O O O O 0 0 TO O O T O O o T O o o

52x14in
C10 MC
/C21',... I R12 R10
-- Cl2

/
I+

-e
---5
R23 D2
1

C19
L
-6
ó-"ShO
I
C15 21 13 CI11
C2
-0,...p
1
I

R19 sh o 5 52

---4 3---0c 3 4

.
f3
I C21

,
\ C18 I+
O
41 c
U
04

VR1 R18 -R13-\

-R7-
i

L.
20
R15- R11- Mixé
-ve
Fig. 4: The two sides of the IF amplifier board, shown actual size, illustrating component layout
and wiring.

Three test points are shown on the circuit, Fig. 1,

IF ALIGNMENT and the multi-range meter is clipped to these for
This can be carried out with the aid of a high - aligning the IF amplifier by this method. Initially,
resistance voltmeter, or the 2.5V range of the usual meter negative is clipped to A and meter positive
type of multi -range meter, preferably with a resist- to B. Maximum signal strength at the diodes will
ance of lOkl/volt or better. It is assumed that if then produce maximum voltage from A to B, as
alignment equipment for FM receivers is available shown by the meter. All the IFT cores are adjusted
the means of employing this will be known, so the for maximum meter reading and each core should
method of alignment described here is an alternate have quite a sharp tuning peak, seen by observing
method. the meter while slowly turning the core.
221
 For the second stage of adjustment, the meter is Where no signal generator is available, the only
clipped from point C to chassis, the polarity being method is to tune the .receiver until some signal is
unimportant. The bottom core of IFT4 is then obtained, and to work on this by ear, adjusting all
adjusted for minimum reading on the meter. In cores for best volume and the bottom core for best
addition to the usual upwards movement of the results with an FM transmission. This can prove
meter pointer, some backwards movement can nor- reasonably satisfactory, unless the IF circuits are so
mally be seen. By rotating the lower core one way or far off tune that the strongest transmission available
the other, it should be possible to make the meter cannot be heard.
pointer move backwards or forwards from its mini-
mum position. Set the core so that the meter shows
this "zero". This completes the IF strip adjustment. INSTABILITY
When making these adjustments, a properly fitting With three IF stages and double-tuned trans-
plastic trimming tool should be used. It is helpful formers it is quite possible for IF instability to arise.
to have a signal generator of the usual type employed This depends on the individual transistors, position
with AM receivers and to tune this to 10-7MHz. A and length of leads and similar factors. It is heard
lead from the generator is placed near the receiver as whistling or hissing accompanying signals, or as
mixer, to secure sufficient input to allow an indica- oscillation liable to start when the IFT's are aligned,
tion on the voltmeter as described. When the genera- but which ceases when some cores are slightly
tor output is amplitude modulated, this will be heard staggered.
in the speaker, but the adjustments described are Where a small adjustment of some cores prevent
made with the generator giving a CW output. this, and results are good, no modification is neces-
Unnecessary adjustment to the cores before sary. Otherwise, the trouble can be cured by placing
obtaining results is best avoided, as they are approxi- a resistor between pin 5 of one or more IFT's and
mately adjusted when the IFT's are manufactured. the corresponding base lead. This is most easily done
Should IFT's be used which are so far out of adjust- by disconnecting the base wire from the pin, so that
ment that no signal can pass through the IF strip, the resistor can be soldered directly to the pin, under
couple the signal generator to the base of the last the board. A similar result is achieved by placing a
IF amplifier and adjust the last IFT. Then transfer resistor in the lead from collector to pin 3 of the
the generator input to the previous amplifier base following IFT.
and adjust the third IFT. After taking the input The values of the resistors are not very critical,
to the first IF amplifier base and adjusting the second except that unnecessarily large values will reduce
IFT transfer the input to the mixer in the way gain. A number of small resistors from about 22f1 to
described, and carefully check all the IFT's. 22051 or so can readily be tried. In the original IF
strip a value of 10051 was used in the first stage, with
vR1

0
R24
to
o
o
o
o4, -.4R29 +.4
o
0C24 0
C
R32
e-- C2 0 39f1 resistors for each of the following stages.
Though the amplifier can be tested and roughly
aligned when clear of the receiver, final adjustments
should be made with it fixed in its normal position.
Four holes are required in the metal chassis, so that
111 Battery
the lower cores can be reached. Final slight re-
N adjustment of IFT4 can be made by ear, when a
CY o: -ve transmission is tuned in. A simple 10.7MHz align-
TT
-.R27}--Sc e
ment generator is described later.
o
b COILS
R28 1---0 e M cI Band 3 was covered with Denco miniature plug-in
1 o .-(R30)--e o coils Range 7. A "Yellow" coil is used for L3 and
et-{ C26 1-- 4 o "Red" coil for L2. This is the most generally useful
band. Band 2 is covered by using a similar pair of
CKG66 coils, Range 6. The Range 5 coils, which have cores,
22x2m,"' cover Band 1. All these coils are the valve type.
For Band 4, coils were wound using Denco plug-in
formers. Place the former in a valve holder before
soldering to the pins. Ll is 212 turns spaced lain.
and tapped at 1 turn from pin 1, for pin 9. L2 is 112
turns, spaced lain. Both are 22swg or similar wire.

AF AMPLIFIER
This is assembled on 0.15in. matrix Veroboard, in
a similar way to the IF amplifier. The board is 212in.
x 2in. and both sides are shown in Fig. 5.
Transformer T2 has lugs which pass through slots,
which can be made by drilling small holes closely
together, and the lugs are twisted to hold the trans-
former to the board. Two 12in. 6BA bolts secure tags
which form the chassis (positive) return.
The wiring of this unit should prove to be quite
Fig. 5 Details of the audio amplifier board, full size. straightforward. Observe the polarity of electrolytic
222
capacitors and put sleeving on any leads where this The parts are assembled with glue and panel pins.
is necessary to avoid short-circuits. Two thin flexible Four loin. strips are glued flush with the front edges,
leads are soldered to the secondary tags of T2, for inside. The receiver can then be inserted as a com-
the speaker connections. A Veropin or projecting plete unit from the back.
wire is provided for the connection to VR1 and Bolts through the holes which are punched in the
another for fixing a black flexible lead for battery chassis flanges hold the receiver in the case. The
negative. back is thin plywood or paxolin, held by small wood-
A great advantage of this circuit is that it provides screws.
quite high gain while the DC operating conditions of An extending telescopic rod aerial can be fixed to
each stage are isolated from those of other stages. the left-hand side and connected by a short flexible
The specified transistors are readily available, but if lead to the co -axial socket. The latter can also be
similar types are to hand it is quite likely that they used for an external aerial.
could be used. In some casés, the value of one or
more resistors might have to be changed to suit the
transistors. This is especially so in the output stage,
where unsuitable values may cause high battery AERIALS
drain on the one hand, or very low drain with In those areas where VHF transmissions are nor-
distortion, on the other. mally well received a telescopic aerial or short wire
It is quite a good plan to test the AF amplifier by should be quite adequate. The wire can be 2ft. to
itself, when it is completed. This is done by taking 6ft. or so long. The position of the receiver and aerial
an AF input to the volume control VR1, which may can influence volume, even with a vertical aerial.
be left in circuit to avoid overloading. The speaker It is also easy to try wires which are very long in
and battery are connected when the amplifier should terms of wavelength and part of the aerial system
draw about 10mA, rising to 25-50mA or so with can then be out of doors. But with rather long wires
ample volume. the chances of 10.7MHz breakthrough are increased.

This photograph shows the position of the IF and AF boards on top of the chassis.

The negative feedback is not essential and R34 Best possible results are obtained by making a
may be omitted or changed to between 470 and VHF type aerial of suitable dimensions for a chosen
680k0. If used, connect it from driver base to one band. The aerial can then be high and in the dear
output transistor collector at T2 primary. If volume outside, a co-axial down -lead going to the receiver.
falls slightly, this is correct. Should oscillation begin, This can give a very great increase in signal strength.
transfer the connection to the other collector.
As the first AF stage is followed by two stages of ALIGNMENT GENERATOR
amplification, a noisy transistor here will cause a
hiss in the speaker. This was so in the amplifier If necessary, a simple IO.7MHz alignment genera-
shown and was traced to the use of a noisy, cheap tor can be built using the circuit shown in Fig. 6.
surplus 0071 in the first stage. When this transistor Trl is an audio oscillator and output from this may
was replaced, the noisy background ceased. be taken, via the isolating capacitor Cl, from the
"AF" pin. This output may be useful for checking
the AF circuits as well as providing amplitude modu-
CABINET lation (and a certain amount of FM also) of the RF
The cabinet is made from 14in. plywood. Each side oscillator Tr2. The RF oscillator is tuned by means
is 514 x 412in. and the top and bottom are 858 x 412in. of the core of Ll and output can be had via CS at the
An aperture to match the small internal speaker is "RF" pin. Enough input to the IF strip may be
cut in the right-hand side and covered with speaker obtained by just placing the generator near the
gauze or similar material. circuits of IFTl.
223

www.americanradiohistory.com
 3V to 9V "4 Fig. 6: Circuit diagram of the simple align-
R1 R4 ment oscillator providing RF or modulated RF
22k 22k at 10.7MHz.
5

Ti 4 C4
52 L1
47pF
w
Audio 3 Cl
ON/OFF I-4AF
5000pF
Tr2
Tri AF 117
OC 71
C5
R2
RF
5.6k
22pF

R3
R5 C2
1k
5.6k 1000pF
51
+ve ' Fig. 7: Most of the components for the
oscillator are mounted on the circuit board
shown below.
MID

Constructing this generator is straightforward. A

Sin. x 2in. flanged "universal chassis" member has
its flanges cut 2in. from one end, so that a 2 x 2in. T1
section can be bent at right angles. Two toggle o
switches (S1 and S2) are mounted on this part, near -ve
o
the top and edges to clear the transformer Tl. o o
The generator is assembled on a small piece of
Veroboard, as in Fig. 7. Drill the board for the pins o o o o o0
of Ll and Tl and for two 12in. 6BA bolts, which with C2 uk-il R2 1-0
extra nuts will provide the chassis return and allow
the wired board to be mounted in the small chassis 24x18in./
described. Two Veropins are inserted, at the points
"AF" and "RF" so that leads can be clipped or
soldered on, if wanted. If preferred, two small sockets
C2 -1r -R2 0 0 0 0
51

could be mounted between the switches and be wired O 0 O

to these pins. Rl o o o 4 o o
- ve
The circuit was found to operate with any battery

-
from 3V to 9V. When S2 is open, an audio tone Cl o 0 0 o o'o
accompanies the signal, when this is tuned in. With 0 0 0 0 0
S2 closed, no modulation is present. The modulated o 2 0 ° 1.O o
RF AF

S2

signal is more easily found on a receiver or obtained

through the IF amplifier, but the unmodulated signal
is used for final alignment, in the way explained.
If an accurately calibrated receiver is available
set this to 10.7MHz and rotate the core of Ll to
tune the generator accurately to this, with S2 closed
for final adjustment. If an accurately calibrated
signal generator can be borrowed (but will not be
available later) set the generator to 10.7MHz, tune
this in on another receiver, and adjust Ll (with S2
closed) for zero beat.
With an FM receiver with 10.7MHz IF, place the
alignment generator near this and adjust Ll to the
correct frequency. If no such receiver is available,
open S2 and place an insulated lead from the "RF"
pin near the 1st IFT of the IF amplifier, which
should give a strong enough signal for the core of
Ll to be adjusted. Subsequently, reduce the coupling
as much as possible, so that the IFT cores can be
peaked as described, with S2 closed. There is no need
for the IFT's to be exactly on 10.7MHz provided all
the cores can be peaked and are still free to be
As can be seen here the oscillator is very small and is easy to construct. moved either way.
224
 AGflETIC
AMPLIPIERS I. R.SINCLAIR
PART 1

MPLIFICATION of d.c. and very low frequen- well as the wires, they have a considerable effect, and
des with very high gain, no valves or transis- current will flow even if there is a gap in a circuit.
tors, high output power capabilities-these If we imagine a magnet as a "cell", having two
are some of the advantages of magnetic amplifiers. terminals and a magneto-motive force corresponding
Despite all these advantages, magnetic amplifiers are to the electromotive force of a cell, and the magnetic
hardly ever used outside industrial electronics, yet effect as a flow of magnetic current, or flux, then the
they could be of great use in many amateur applica- similarity is obvious. Add to this the idea of
tions calling for low frequency amplification; appli- magnetic resistance or reluctance for each piece of
cations such as motor speed control, photoelectric the magnetic circuit and we can make a Kirchoff's
amplification; temperature control, or servo systems. Law for the magnetic circuit.
Probably the strongest reason for this is the lack MMF =R1 X N1 +R2 X N2
of complete information on the working of a mag- where R is reluctance (magnetic resistance) and N is
netic amplifier, textbooks either describing the magnetic flux.
amplifier as if magnetic theory were well known to
the reader, or ignoring them altogether. This article
sets out to fill the information gap.

MAGNETIC CIRCUITS
One of the causes of the information gap is the
way in which magnetism is taught in schools. We
learn about magnetic poles and the simple "laws" of Magnet flux N

magnets as they were known 150 years ago, but rcurrentl

nothing of the later developments in magnetic theory
which made the solution of magnetic problems so
much easier. We cannot, in this space, even attempt
to outline the whole of modern magnetic theory, but
we can take a look at the part of magnetism regard-
ing magnetic materials and magnetic circuits which
Soft iron (R1)
forms the basis of magnetic amplifiers. Air gap (R2)

- Fig. 2: The magnetic equivalent circuit of Fig. 1.

-24H+ I
Fig.1 Simple circuit
:
to demonstrate Kirchoff's This idea is useful in the design of transformer
Second Law. cores, relays, and other electromagnetic devices but
Rp
cannot be used as simply as Kirchoff's Law, because
R1
the reluctance is not as constant as the simple resis-
tance of Kirchoff's Second Law, but varies with the
flux. Despite this complication, however, the idea of
Figure 1 shows an electric circuit with a cell a magnetic circuit is useful, especially since the
producing a current through two resistors in series. greatest reluctance in most magnetic circuits is the
Now the voltage (electromotive force) across the air -gap (or any other gap not closed by magnetic
cell is equal to the sum of the products of current materials) which is constant at any value of magnetic
times resistance for each resistance, or to use the flux.
mathematical form, V=R1 Xi+R2Xi, which is It is rather like the case of a circuit of several
Kirchoff's Second Law. This electrical circuit is simple resistances in series, all about 10052 but varying with
to deal with because the flow of current is exclusively current (as thermistors do) except for one which is
in the circuit with no current flowing in the air about 15K52 and which "swamps" the others. In
around. the same way, the large reluctance of an air -gap in
We can draw a very close comparison between the a transformer core makes design easier because it
electric circuit of Fig. 1 and the electric magnetic makes it unnecessary to bother too much about the
circuit of Fig. 2, but with the exception that magnetic precise reluctance of other portions of the circuit.
effects can be detected in the air around a magnet Incidentally, the idea of MMP is used mainly with
and do not confine themselves to the metal portion electromagnets. When permanent magnets are incor-
of the magnet. Designing magnetic circuits is rather porated in a magnetic circuit, as in polarised relays,
like trying to design electric circuits to work in salt they are treated as a "negative reluctance" which
water; though the surroundings do not conduct so contributes flux, rather than as a source of m.m.f.
225

www.americanradiohistory.com
 MAGNETIC FIELD STRENGTH AND FLUX The value of B left when H=0 again is called the
DENSITY remanance and measures the ability of the material
to be permanently magnetised. To reduce B to zero,
If we wind a solenoid and pass a measured current an opposite value of H (called the coercivity) must be
through it, we find that the magnetic effect, provided applied. As the values of H in the opposite direction
that no iron or other magnetic material is present, are increased, the curve traced out becomes the
depends only on the current i, and the number of opposite of the one previously traced, but the first
turns of the coil per unit length. For a very long coil, portion of the graph is never traced again unless
the magnetic field strength is simply H=NXi, and H the iron can be completely demagnetised (by heating,
is measured in units of amperes/metre. As far as we for example) and the experiment repeated.
are concerned this is a measure of the force which
this solenoid would exert on a compass needle at a
distance.
If a core of iron or any magnetic alloy is now
placed inside the coil, the effect on a compass needle
is greatly increased. The magnetic field has mag-
netised the iron, and the two different effects are
adding together. We can measure this in the same
way, but several old and confusing mistakes can be
avoided if we measure this new effect by using
induction. When a current changes in a coil which C;(749

is wound on the same core as another, there is a

voltage induced in both coils which is proportional Fig. 4: Simple magnetic amplifier. The DC input to the 'primary'
to the number of turns and the rate at which current is not a mistake! See text.
is changing. The quantity which changes the iron
core is the magnetic flux which we met earlier and The interesting portions of this curve, called a
is measured in Webers or volt-seconds. hysteresis curve, for our purposes are the steep sides
We find that_the effect of a solenoid with an iron and the flattened top. When the current in the coil is
core can be mesured by dividing the flux in the core at a value corresponding to point A on the curve,
by the area of cross-section of the core; this unit is the flux density changes considerably with a change
called flux -density, and it is measured in Teslas of current, a condition which is ideal for a trans-
(T=1 Weber/m2) and given the symbol B. former or choke since it means the greatest possible
reverse voltage, and so the maximum inductance.
When the current in the coil is at a value above point
RELATION BETWEEN B AND H B, the change of flux density is very much less, and
If we set up the solenoid of the first example with the material of the core is said to be saturated. In
an ammeter for measuring current, so that we can this condition, an increase of current in the coil
calculate H and a search coil close by connected to causes very little increase of flux density, very small
a flux meter so that we can measure B, we can place induced voltage, and so very little opposition to
a magnetic material in the core of the solenoid and change of current (low inductance) so that large
measure both B and H over a range of values. When currents can flow. A core which includes an air gap
we do so, we get a graph of the kind shown in Fig. 3. limits the flux density because of the reluctance of
Starting from H=0 and slowly increasing, the curve the air gap and so reduces the possibility of satura-
rises sharply and then flattens off until the rate of tion, which can have serious effects in transformers.
rise is equal to the rate of rise of H. When H is A core which consists of a circle of magnetic material
decreased again, the value of B does not take the will saturate easily because of its low reluctance.
same values as it did on the way up. Many text books quote the permeability of a
magnetic material it as if it were a constant. As can
be seen from the curve of Fig. 3, it is not a constant,
but varies with the magnetic field strength, so that
the only value which has any real meaning is the
maximum permeability, the value of µ at point A on
our curve, because this indicates the usefulness of
the material for a transformer core.

A SIMPLE MAGNETIC AMPLIFIER

Figure 4 shows the circuit of the simplest form of
magnetic amplifier. This consists of the choke Ll
which is provided with two windings on a core of
material which saturates easily (no air gap) and
which has a very small area enclosed by the forward
and return paths, meaning that the energy spent
in magnetising and de -magnetising the core is not
too large. Such a multiple winding choke (it is not a
transformer, despite the similarity of the symbol) is
termed a reactor. The winding marked 3, 4 is used
as a choke in an a.c. secondary circuit, and the
winding marked 1, 2 is used to apply magnetic flux
Fig. 3: Graph showing relation between 'B' and 'H'. (Note: For to the core by passing a steady current. The winding
'remanace' read 'remanance'.) 1, 2 is usually known as the control winding, and a
226
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SA25
WATTS RMS.
£2.95
transistors diodes
free addition of components costing less than 5p.

25
£8.90
7 7

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SA35 transistors diodes

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THREE CHANNEL SOUND TO LIGHT UNIT
Handling the total of 3000 watt (3kw) this unit Is unique for its price in that not only bass, middle and
SA100 £10.90
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etc. Supplied in Tough Steel case for free mounting or panel fixing.
100 WATTS RMS. 11 transistors 6 diodes
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ALL THREE MODULES HAVE OPEN £ SHORT CIRCUIT MONO VERSION £6 50 carr. 20p (As Illustrated. S.A.E. details 9 volt operation) Outputs up to
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ONLY ADVANCED DESIGN TECHNIQUES MAKE THESE
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e
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BRIEF SPEC. FOR ALL THREE MODULES
t Ó o~Ó Q IP '! SAXON STEREO
Freq. response 15-40,000 Hz ± 1dB
tA00t1 919X/ -140001x CONTROL UNIT
Distortion 0.2% at 1 kHz
Two decks, and lull headphone monitoring. The unit is mains operated and measures 17? x 3' x 4' deep
Loads 4 to 16 ohms end is finished with a smart white on black facia. The controls are: Left/Right deck fader, volume, bese,
Quiescent current 15 mA treble, Headphone Selector and volume, Microphone volume, bass, treble, mains on/off.
THIS IS A MUST FOR THE HOME BUILT HIGH QUALITY DISCOTHEQUE AND IS COM-
Noise Better than -75 dB PARABLE TO UNITS AT OVER TWICE THE PRICE. (N.B.-Stereo only has mic input.)
Supply voltage SA25/35 25-45 volts
SA100 40-70 volts
Size
4' x
x 1' (SA25/SA35)
COMPLETE AMPLIFIERS
Circuits, connecting Instruction and application data are supplied CSE 100. £34.90 carr. free
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THE SA25/35 & SA100 AUDIO MODULES wide range bass end treble controls. Ideal for small groups D.J.S., etc.
PU45 Unstabilized supply for 2 SA25/35 £4.90 SAXON 100 £4850 cary. free With an RMS output of 120 watts speech and music,
100 watts continuous power, tour individually
PU70 Unstablllzed supply for one or two SA100
£7.75 cary. 45p controlled FET Input stages and wide range base
and treble controls, this amplifier has established
PS45 Stabilized module for 2 SA25's or two SA35's itself as a unit offering quality and reliability at low
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MT45
MT30
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rectifier diodes mounted £3.50 carr. 2Cp Boxes Smart Regine
PS70 Stabilized supply module for one or two SA100's LOUDSPEAKERS British made bargains!! finish £15 carr free.
£4.90 carr. free 12' 25 watt 8/15 ohms £5.95 carr. 30p. 15- S0W.8/15 ohm £14-S0 carr. 50p.
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MT70 Transformer for PS70 £4.90 carr. 40p
ALL MODULES ARE BUILT ON A.K.G. MICROPHONES suitable for disco, group or general P.A. use,
D11 DHL IDEAL DISCO MIKE ONLY £945 (rrp £11.00). SEND SAE FOR
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AND ARE SUPPLIED FULLY TESTED All prices subject to VAT at standard rate ON ALL MICS.

Orders and personal shoppers to:

SAXON ENTERTAINMENTS LTD., 327-33 I Whitehorse Rd., W. Croydon, Surrey. CRO 2HS.
Telephone 01-684 6385 TERMS OF BUSINESS
Hours 9.30 a.m.--5.30 p.m. Cash wich order (C.W.O.) For C.O.D. please add 35p
TRADE & EXPORT ENQUIRIES INVITED extra, cash by regd. letter, please

227

www.americanradiohistory.com
 Why pay more - look at our
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BLOCK CAPS please

228
choke La is wired in series with this winding to
prevent a.c. being fed to the control voltage source
through transformer action in the reactor.
Imagine that no d.c. is applied to the control
winding. The winding 3, 4 then acts as a choke
(providing that the current through it is not too
large) so that only a fraction of the alternating
TI EWSIDfl
voltage applied to the secondary circuit can appear
across the load resistor. If now some current flows
in the control winding, the condition can be reached
where the sum of flux due to the control winding JULY ISSUE
and flux due to current in the secondary winding
cause the core to saturate. At saturation, the induc-
tance of the secondary winding is very low and a high RENOVATING THE PHILIPS G6
current flows in the load, so that the average current CHASSIS
through the load increases. This is equivalent to Continuing his series on renovating and fault
shifting the bias conditions of the amplifier, and this finding in ex -rental colour chassis Caleb Bradley
shift in the operating point is shown by the curves starts to work this month on the first Philips
of Fig. 5. chassis. We've plenty of tricks to tell you on
this one.

DC RESTORATION CIRCUIT
Many single -standard monochrome chassis
have a perfectly stable vision signal at the
detector but then lose the black level through
a.c. coupling in the video section. Keith Cummins
has developed a circuit to give d.c. restoration
at the c.r.t. cathode however. Development was
undertaken using the popular BRC 1500 chassis
but the circuit could be adapted for other chassis.

WORKSHOP HINTS
Vivian Cape! turns his attention to tuning
capacitor gangs, both radio and TV receiver
types, describing the fault conditions that arise
and methods of dealing with them.

COLOUR RECEIVER INSIGHT

Much insight into colour can be obtained by
Fig. 5: At A, µ=Ñ Is high, and the inductance of the coil (proportional examining the wide variety of circuitry used in
to µ) Is high, At B the reverse obtains. different chassis. This month we take a look at
the Korting 51763 series which incorporates many
novel features including an unusual ident stage
This type of magnetic amplifier is known as a and tube protection on the event of field collapse.
straight -saturating amplifier and is seldom used
because the sensitivity is low and the waveform FAULT FINDING GUIDE
across the load is distorted. It does, however, illus-
trate well the principles involved in magnetic This month John Law switches his attention
to a typical i.f. panel (Bush TV141/Murphy V159
amplifiers, and is easy to construct. The current series) and describes the faults that arise and
amplification produced is equal to the ratio of turns trouble -shooting procedures to be adopted in
of the control winding to the turns of the secondary this part of the receiver.
winding (that is, the same as the ratio of a con-
ventional transformer); note that the step up is PLUS ALL THE REGULAR FEATURES
from d.c. in the control winding to a.c. in the secon-
dary winding so that this offers a method of control-
ling a.c. by means of a d.c. source.
WM.
--rr.r.--
TO
(Name of Newsagent)
SELF SATURATING MAGNETIC AMPLIFIERS
For many purposes, greater sensitivity and a Please reserve / deliver the JULY issue of
better waveshape are required and these require- TELEVISION (20p), on sale JUNE 18 and
ments have resulted in the self saturating magnetic continue every month until further notice
amplifier, which uses the secondary current to con-
tribute more to the saturation of the core. This is NAME
achieved by making the secondary current travel
only in one direction in the core. If the core is already
saturated by the control current the inductance is ADDRESS
very low and the secondary current is unimpeded.

TO BE CONTINUED NEXT MONTH L. rr

229

www.americanradiohistory.com
 ELECTRONIC IGNITION
A recently announced transistorised
ignition system from Dolphin Designs

1RODIJCTION has its casing made from diecast

aluminium with a special epoxy finish.
All metal parts are cadmium plated
and connections are through water-

IIÌ1ES cob riches

tight glands. All metals are plated to
prevent electrolytic corrosion and the
circuit is built on a fibreglass board
with a double thickness of copper.
The unit is designed for 12V cars with
either positive or negative chassis.
4D STEREO separate from the direct sound of the
front two speakers.
The outputs from the amplifier
channels are fed to the 4d unit. The
four speakers are then plugged into
DIN speaker sockets on the unit and
the large knob can be rotated to
control the volume of the back two
speakers.
By use of the 4d unit, a 4 -channel
effect is produced which gives a
very pleasing sound. In the unit
(shown) the push-button marked
"front" disconnects the back two
speakers so that the stereo amplifier
can operate as a normal 2 -channel
system. The push-button "test" is
used to adjust correct balance A dash -mounted switch will revert
between the two front speakers. the car to conventional ignition whilst
This isa Scan-Dyna 4d stereo unit. One point of warning, however, it is driving either for comparison or the
Used in conjunction with a stereo essential that a correct phase con- unlikely event of failure. The ignition
amplifier and 4 speakers, it damps nection is made between the amplifier system is priced at £12.95, plus 30p
the direct signals to two back and the 4d unit. Price is £12.90 plus postage, plus VAT, and is available
speakers, permitting the reflected VAT and your local hi-fi dealer from: Dolphin Designs, 59 Leighton
sounds from the back to be made should have 4d units in stock. Avenue, Leigh -on -Sea, Essex.
PEAK PROGRAMME METER ADVANCE ALPHA This digital multimeter from Advance
The PPM concept was developed by costs £55. A total of 24 ranges
the BBC for checking modulation indicate d.c. voltages from 1mV to
depths at transmitters, and the 1kV, a.c. voltages from 1mV to 500V,
modern derivative (BS 4297) is used d.c. and a.c. current from 0.1µA to 1A
in the broadcasting and sound and resistance from 0.1f1 to 10MO.
recording fields. The standards de- Two other instruments in the
fine attack and decay times and Advance "pipeline" are the TC17
logarithmic meter scaling, with posi- timer counter and DVM44 digital
tive and negative peak detection as voltmeter. Advance Electronics Ltd.,
some sounds have + and - levels
differing by up to 8dB. The drive
Instrument Division, Raynham Road,
Bishops Stortford, Herts.
circuit, produced by Surrey Elec-
tronics is for 1mA L.H. zero meters
and is available as a kit at £8 or
built and aligned at £12.
The attack time is 2.5mS, decay
rate 1dB per 100mS and detection +
and - peaks within 0.5dB. Display
is a log. meter scale of 6 with 4dB
divisions (-22 to +4) or BBC style
1 to 7. Accuracy is within 0.3dB and

frequency response -0.5dB (20Hz-

20kHz) -1.0dB (12Hz-30kHz). Input
impedance is 100kí2 and supply is
from +24V to 50V. Consumption is
25mA.
Ernest Turner special "ballistics"
meters type 642 cost £9 and 643
£10.70. Further information from:
Surrey Electronics, 24 The High Street,
Merstham, Redhill, RH1 3EA, Surrey.
230

www.americanradiohistory.com
 I.L.P. (Electronics) Ltd

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component integration. The use of specially developed high thermally conductive alloy
and encapsulant is responsible for its compact size and robust nature.
The module is protected by the generous design of the output circuit, incorporating
25amp transistors. A fuse in the speaker line completes protection.
Only 5 connections are provided, input, output, power lines and earth.
OUTPUT POWER: 100 watts RMS; 200 watts peak music power. INPUT IMPEDANCE:
10kt). INPUT SENSITIVITY: ODhm (0.775volt RMS). LOAD IMPEDANCE: 4-162.
TOTAL HARMONIC DISTORTION : less than 0.1% at 100 watts, typically 0.05%.
SIGNAL : NOISE: better than 75Db relative to 100 watts. FREQUENCY RESPONSE:
10Hz-50KHz +1Db. SUPPLY VOLTAGE: ±45volts. APPLICATIONS: P.A., Disco,
Groups, Hi-Fi, Industrial. PRICE: £14.90 inc. VAT & P&P. Trade applications welcomed.

CROSSLAND HOUSE NACK INGTON CANTERBURY KENT ° °

CANTERBURY 63218
Please note we reserve the right to substitute at our discretion updated versions of advertised designs
where applicable.

231

www.americanradiohistory.com
 Now available from one company are complete kits for
many of the articles published in the Electronics, Radio
13PITCH BOARDS £39.50. Kit contains all the
capacitors and semiconductors as published, but not the
resistors,
and TV Journals. Examples of our range are: P.C.B.'s or the inductor.
LIGHT DIMMER. Kit contains all parts including circuit
and construction data, 480 watts, fully suppressed.
SCORPIO IGNITION SYSTEMS (P.E. Nov. 1971) Price £2.10.
£9.50. This kit includes all the parts for the assembly
of this popular and reliable system. The hardware and MUSIC MAKER ELECTRONIC ORGAN (P.W. Nov.
the construction data are included. 1972) complete kit £4.40 or kit less resistors, P.C.B. and
plastic box £2.80. Stylus not supplied.
DRILL SPEED CONTROLLER (E.E. Aug. 1972) MIGHTY MIDGET (P.W. Jan. 1973) kit contains all
Kit consists of resistors, rectifiers, thyristors and tag parts, less the battery, box and knob, £2.25.
board as specified in the article, price £1 -15. Kit with TRIFFID RADIO (P.E. Feb. 1273). Kit includes all
M.K. box, switch and plate included £2.30. parts listed, less "tuning coil" and "miscellaneous
components". £4.95. Ferrite rod and wire, optional extra
ELECTRONIC PIANO (P.E. Sept. 1972) at 50p, P.C.B. optional extra at 65p.
We can supply the various sections for this article in kit
form:- We shall be offering kits for most articles published in
the popular electronics magazines and will be pleased
POWER SUPPLY £6.60, including all semi -conductors, to quote prices. Send for details of kits available (please
resistors, capacitors, transformer, heat sink and hardware enclose S.A.E.).
less P.C.B. All kits sent post FREE, within the limits of the UK
PREAMP AND TREMELO £3.20, complete with switches We regret that prices shown do not allow for V.A.T.
hardware and electronic components, less P.C.B. Please add 10% to your order.
MAIN AMP £4.20, complete with IC -12, electronic Please note we reserve the right to withdraw kits without
components and P.C.B. prior notification.

12Lauderdale Road, London W.9.

Telephone 01-286 0011 Telex 28479
Use Access here

E/sr/rL7k/I
o
SAVE TIME TRANSFORMERS SHORT-WAVE
ANDjt MONEY DOUGLAS GUARANTEED
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INCLUDING V.A.T. 12V x2 lA x 2 MT 71 ATO 1189
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12 or 24 volt.
80 volts. All tapped at 0-12-15-20-30V.
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500 mA MT112CTO 8141 4A MT21 AT 8883
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50 volta. All tapped at 0-19-25-33-40-50V.
500 mA MT102 ATO £184 3A MT105 AT 14-75
lA MT103 AT £255 4A MT108 AT 8802
2A MT104 AT 1876 5A MT107 AT 8867
80 volts. All tapped at 0-24-30-40-48-80V.
500 mA MT124 ATO 81.94 2A MT127 AT 1898
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As supplied by us to SCHOOLS, TECHNICAL 20VA 0-115-210-240 XMT113 CT 8148
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Silver grey .cove enamelled steel cabinet with 150VA 0-115-200-220-240 XMT 4 AT 12-71 ment of quality, "H.A.C." were the Original
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45 transparent styrene drawers fitted with amateur constructor. Over 10,000 satisfied
moulded handles and label slots. Dividers can be 300VA XMT 86 AT 1484
supplied at an extra charge to enable each drawer 400V. Output at 50Ha. Ref. ITS AT Price customers-including Technical Colleges, Hos-
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parent drawers allow swift selection of com- Wireless World 8285
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onents at a glance and eliminates duplication Sec. output (rams.) Ref. No. Complete kit-price £385 (incl. p. & p. & V.A.T.).
of stock. A really first class time saving unit. Price
Size of cabinets 21}' o 11}'x or. Sloe of 3-0-3 V. 200 mA MT238 CSt 8118 (lrstumer writes: "Australia, India and .America
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12-0-12 50 mA MT239 CSt 8148 have logged c r 130 stations, plus countless
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0-15-27 x 2 lA x 2 MT204 AT 84-09 of other S.W. kits, including the famous model
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232

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 . or-]
L.A.J. IRELAND
Number 39 SGS TBA435 VOLTAGE REGULATOR

STANDARD portable transistorised equipment adequate heat sink. The circuit is, of course, fully
commonly operates from a 9 volt battery protected against overload and even short-circuit
supply. When the occasion arises for such conditions, while maintaining the rated output vol-
devices to be operated from a 12 volt supply, for tage to within 1% over the design range.
example on a car battery, it is clearly necessary to The operation of the protection equipment is fully
provide some form of voltage dropper. This is not illustrated in Fig. 1, which clearly displays the drop
as simple as at first appears, due to the common in output voltage if an attempt is made to exceed
use, for example, of class B output stages in port- a safe current. When in automobile use, it may be
able equipment. Since it is not a constant current found advantageous to precede the regulator with
load, therefore, it is impossible to insert a simple an RF choke, to prevent ignition interference enter-
resistor to provide the reduced supply voltage. ing the system through the power supply lines.
Neither is a potentiometer arrangement adequate, However, the IC itself has a capacity to reject ripple
since it requires a standing current greater than the and high frequency noise by a factor of some 50dB,
drain of the device in use. Zener diodes face a a property which is highly significant both for mobile
similar objection, and the integrated circuits avail- and mains -driven equipment.
able to date have generally required complex inter- R.F. choke
connections and several discrete components to set
the required output voltage. Hence the advantages +o-1000 TBA 435 e...a+8.5V
of the TBA 435, a simple three terminal device
specifically designed to provide a fixed output vol- Car battery ,o1iF jai
tage of 8.5 volts when operated from any power
source between 10-5 and 20 volts. Its applicability o ,oyFT, 00
to the problem of operating 9 volt transistorised
equipment from automobile power supplies is
obvious.

Performance
The device is capable of supplying continuously Input
a current of over 100mA. at the rated output vol-
Output
tage, representing an internál power dissipation of
0.75 watts, increasing to 4 watts if mounted on an
Fig. 2: Practical application of TBA435 and connections for 100mA
10 and 600mA types.
9 It might be of interest to point out that the TBA
e 435 is merely one of a series of similar three-
V;,, =15V terminal integrated circuit voltage regulators with
7 analogous operating parameters but with a range
6 of output voltages. In any case where a power
a supply must provide a well regulated protected .out-
5
5 put at a fixed voltage, the appropriate unit from
4 this series should certainly be evaluated for the
application.
3

2
TBA L TBA TBA L TBA L
Type 625A 005 435 6258 036 625C 037
1

(CKG<) Output voltage 5 5 8.5 12 12 15 15

0 RatedcurrentmA 100 600 100 100 600 100 800
0 20 40 60 80 100 120 140 160
Output current -mA
Fig. 1: Output regulation curve. Note action of protection circuit as
Note: The NE555 reviewed in the May issue is made
rated current is exceeded. by Signetics and not SGS.
233
 No. 100
ractically Ton
Wireless Up

HENRYcommentary by
NOT until one of my col- Monthly, one reads glowing profit in service. The retailer does
leagues and regular readers tributes in the enthusiast maga- not regard good service as neces-
reminded me of the passage zines from readers who, despair- sarily fostering goodwill. In our
of time was I aware that this con- ing of help from local dealers, own establishment, the 'Boss' is
tribution is the hundredth Old took their gear to the manu- fond of saying: 'One second com-
Henry has made to PW. Have facturer, and had satisfaction. I plaint outweighs twenty well-done
you really endured me that long? feel a bit wry about that-better jobs.'
Anniversaries are a time for that the manufacturer should give Which brings me to my second
recall and for resolution. Recall
is a facet of Henry's waffling that
his local agent good backing.
I have even read examples of
grievance .... It is possible to
make service pay, but only if it
may at times have seemed to take 'turn-around' repairs being done is run as a strictly economic busi-
precedence. Resolution should be on equipment for which I have ness. And that, friends, entails
had outstanding parts orders for our paying the true price for
' -rs months, and can only think, with what we have done.
typical Henryesque cynicism, that Take the case of the ordinary
the manufacturer was really interconnecting lead. You can buy
thinking of his `public image'. But made-up packs of practically any
e that's another story.
As good an example as any of
plug or socket to any other for
round about a pound, often less.
the way 'the trade' does not care But if you want a 'special' lead
was to be seen at Sonex, where made by an otherwise busy en-
Donald Aldous wore himself into gineer, you must expect to pay
the ground in organising a series half as much again.
of lectures. During the two trade He has to fit this between other
4,( days, attendance at the lectures jobs, sort out 'matching more
Brimming over with human kindness was abysmally small. often than not, forage among the
saved for innovatory dates, the Practically the only interest was rubble for plugs and disentangle
Chinese New Year, the day after shown when a quadraphonic de- cable, set up his mini -vice and lick
the annual holiday, any Monday monstration was given, when the the end of his soldering iron,
morning . . lecture theatre became half-filled. muttering incantations the while.
Instead, if you'll bear with me, I don't want to enter the sur- In a workshop like ours, where
I would like to blast off about a round -sound arena just now, but one of my colleagues waits till I
couple of subjects that have re- would agree that discrete four - am looking the other way, then
cently roused my ire-and which, channel is the only truly 'hi-fi' way 're -organises' all the drawers of
according to my critics, seem to of doing things: that, just as with
exemplify Henry's approach to gramophone records, mono/
radio design, construction, and stereo, f.m. broadcasting, com-
marketing. mercial radio, colour TV and any
First, the last. And I mean the other technical innovation, com-
retailer; your local friendly promise has resulted from the
dealer, as the Radio & Television needs of compatibility, and we
Retailers' Association would have shall probably have some inade-
us believe. Brimming over with quate system ultimately foisted
the milk of human kindness, in- upon us.
tent on social justice and the The slogan seems to be 'Never
:

welfare of his customers, ineffably mind what's best. What can we

altruistic .. . get away with?' muttering incantations the while
Believe me, the radio retailer Very few dealers are today
who really cares; who came up happy to take in repairs. They will small parts, it is lead -making that
from bright emitters and the days tell you that their service depart- is most sick-making, and wildly
of the catswhisker; who will spend ment is already stretched to the uneconomic.
his precious spare time finding limit to service the stuff they sell. Perhaps that is why the small
better ways of providing P.A. for which, when you think about it, dealer no longer exists, and the
the nearby Old Folks Club; whose argues that either their workshop package -seller who has taken his
advice is geared to needs and not is under -staffed or the stuff they place shuns service: because we,
mere profit: that chap is as rare sell continually goes wrong. you and I, are unwilling to pay
as a fridge in an Eskimo's igloo! The truth is that there is little our whack!
234

www.americanradiohistory.com
 ENLARGER timers generally rely mainly on position 5 then when 45 seconds have elapsed the
charging or discharging capacitors through outputs from the wafer switches are at logic 0 instead
variable resistors and an appropriate switching of logic 1 as they would have been before the begin-
circuit. These timers can give a good repeat accuracy ning of the timing sequence. These two outputs are
of ±0.25 seconds but actual settings can only be as inverted using two nand gates G3 and 4 the outputs
accurate as can be manually calibrated, using a stop of which are applied to another nand gate G5 whose
watch, in most cases no better than ± 12 second mid- output will be at logic 0, when the 45 seconds have
range. elapsed and at logic 1 at any other time.
This IC Timer relies for its accuracy on the mains The output is used to clear the flip-flop IC3 so
supply frequency; it has a very high repeat accuracy, causing it to revert to its original state which blocks
requires no calibration and is switchable from 0-9-9 the 50Hz clock pulses, clears the dividers IC4-7 and
seconds in 0.1 second steps and 0-99 seconds in 1.0
second steps-the accuracy directly proportional to
that of the mains. It has been my experience that the
* components list
0-9.9 second range is useful when printing in colour
when filter changes dictate exposures of seconds and Resistors
R1 47kf1 R5 47f1
fractions of a second. R2 2 2kí2 R6 4 RD
R3 2.2kf2 R7 2712
R4 3 3kû R8 15052
CIRCUIT DESIGN
The circuit uses nine TTL i.c.'s. The timing is All +W 10%
derived from 50Hz mains supply frequency which is Capacitors
obtained from the secondary of T1 Fig. 1 and fed via Cl 0.68µF C2 1000µF C3 10µF
a capacitor Cl to a two transistor Schmitt trigger
circuit the output of which goes to a control All 12VW
gate. The output from this gate goes to an SN7490,
IC4 in Fig. 2, used as a divide by five. The 11)Hz out- Integrated Circuits
put from this goes to a divide by ten, IC5, to give IC1 SN7442 IC4 SN7490 IC7 SN7490
1Hz. Two more SN7490's, IC6 and 7, are used as IC2 SN7442 IC5 SN7490 IC8 SN7400
IC3 SN7472 IC6 SN7490 IC9 SN7400
divide by ten circuits; the BCD outputs of each one
being decoded by an SN7442. The ten outputs of the Semiconductors
SN7442's pass to the single pole twelve way wafer Tri BC108 Tr3 2N2926 DI 40430
switches S2 and 3. Tr2 BC108 VR MVR5V (RS) (400V 6A)
To start the timing sequence S1 is depressed which BR1 50V 1A bridge rectifier
causes a logic pulse to be fed to the input of a flip-
flop of an SN7472, IC3, one output of which goes to Miscellaneous
the control gate G1 so that 50Hz is applied to the T1, transformer 230/6.3V 1A .51, SP biased toggle
switch. S2 and S3, 2 x SP 12 way wafer switch. S4,
driving circuit; and to gate G2 which is connected to SP changeover toggle switch. Veroboards, 31 x
gate G8 controlling the driving circuit. The other 31in. 0.lin. matrix, 31 x 2#in. 0.lin. matrix. Veropins,
output of IC3 goes to the zero reset of the dividers knobs. Case 8 x 6 x 3in. with lid. Reed coil and switch
IC'4-7. for 3-5V operation.
If, for instance, S2 is on position 4 and S3 on
235

www.americanradiohistory.com
 24OV
A.C.
mains

106 07101 Bridge rectifier MVR 5V BC1O8

A Fig. 1: Circuit of 5V stabilised power supply and two transistor

Schmitt trigger arrangement.
y Fig. 2: Diagram of interconnections and supply leads for the nine
integrated circuits.

ION 07111

nnn nOVnn
-
9 8 7 6 5
52
n
}}4 2 1

.
rotor 9 8
i
7

OV1htii
5
S3
4
3
}}2

1
0 rotor

'
14 1

Range
IC4 IC1 IC2
S4 SN749O SN7442 1 SN7442
7 16 16

U
+5V OV
UU U+SV YUUI!UU+SV

nnnnnn OV

e 14
nn OV

14
nnññn

IC5 IC6 IC7

SN 7490 SN 749O SN749O

+5V lb
Switching Reset
circuit (Y)
+5V OV
111

'
14

Exposure IC8
- IC3 IC9
or S t
SN 7400 SN 7472 SN 7400
14 7 14

U U U U U
+5V +5V
YY OV
YY

OV
(earth) 5OHz (Z)

236

www.americanradiohistory.com
switches the triac off via the reed switch. Two nand
gates are connected so as to eliminate contact bounce
at Si (gates G6 and 7).
Switch S4 is an added facility which allows the
circuit to count to ten seconds in 0.1 second steps
and this is achieved by merely short-circuiting one of
the divide -by -ten i.c.'s IC5 causing 10Hz to be applied
to IC6 instead of 1Hz. When either or both wafer
switches are set on positions 11 and 12, closing S1
switches the triac on which is held on until Si is
closed again; this facility allows the enlarger to be
on for focusing.
+5V

Load
R8 150 A2 (to lamp etc) ))

Y
D1 A.C.
switching Tra 40.430 mains
R6 2N 2926
4.7k

OV

-
2N2926
>0712] 40430

Fig. 3: Isolating stage using a reed relay to contro/ the triac switch. The IC board is mounted in the lid of the box on spacers to minimise
the length of the wiring to the switches.

--
1 2 3 l 5 6 7 6 9 10 11 12 13 14 15 16 17 16 19 20 21 22 23 24 25 26 27 26 29 30 31 32 33 34 35 36 31

0 --R- IC
6 Jr 7 1 tr t
9-i
A

f----
1

To 53
(Tens)
4
2
3

5
r--
----+
E

-
0

52
To
(Units) 5-41--
4

-----
5

----r
7
e-4/---.
U

AA
BB
CC

54 ...-To 00

ti
EE

U. 1 IC FF
GG

J
ti!
HH

J )4 J1

24/X(+5V)
35/0 (Z ) To S1
2/I(0V)
Ion 0713]
To 1/N on (Y)
To power supply panel power supply panel
Fig. 4: Placement and wiring of the IC's on the veroboard panel. Note carefully all breaks in copper rails.

237

(
 To D1

1 2 3 4 5 6 71 8 91 10 11 12 13 14 15 16 17 18 19 20 21 22 23 2l 25 26 27 28 29 30 31 32 33 313536 37

4(0V)
To VR/C 0

To AC (0V)
mains (earth)
(0V)

To I C
panel
37/HH M

(Y)
0

To TI 0
sec.
(6-3v) 5

To V R /A
MUD

Fig. 5: Layout of panel carrying the power supply, Schmitt trigger circuit and reed relay.

Although the output of the final i.c. (IC8) to the Unfortunately, due to the high cost of i.c. holders
switching circuit is compatible with the gate current (as much as twice the cost of some i.c.'s) they have
required for the triac, the triac cannot be driven not been used in the construction of this circuit. The
directly as it would mean that all the i.c.'s would be i.c.'s have been mounted directly on to the 0lin.
live and could not be earthed. In order to overcome matrix Veroboard, Fig. 4, care being taken not to
this problem a reed relay is driven from IC8 and the allow the i.c.'s to get too hot although that is not
triac switched from that. Unfortunately the reed much of a problem providing one solders them
relay used is not ITL compatible so an interface quickly and in rotation. The wiring between all com-
circuit consisting of a 2N2926 is used between IC8 ponents should be as short as possible (never any
and the reed relay, Fig. 3. longer than l0in.) so as to prevent spurious
triggering of the i.c.'s.
The construction is fairly straightforward, the
whole unit being mounted in an aluminium box. The
switches S1-4 are mounted on the lid as is the IC
board, held by 2in. long 2BA nuts and bolts with
spacers to provide a stand off so that the wires from
S2 and S3 to the pins on the i.c. board are as short
as possible. For convenience the triac was mounted
on the transformer which was bolted to the case.
The power supply reed relay and interface circuit
for the triac are mounted on Veroboard, Fig. 5, which
is fixed to a piece of aluminium fixed across the
inside of the box.
When the wiring has been completed and checked
thoroughly (without the triac connected) it is possible
to test the timing.
The switches S2 and S3 should be set to each of
their positions and the timing tested: if it is not
correct then one should look for faulty connections,
missing drilled holes in Veroboard and solder bridges.
When testing the timing it is important that the triac
is not connected. Use a meter on the reed switch.
Because of the fact that the triac cannot be driven
directly from the i.c.'s it is necessary to use an inter-
face circuit. The i.c. board output goes to a resistor
and transistor which switches hard-on when it
receives a logic 1 voltage and a reed relay is ener-
The panel of Fig. 5 is mounted on insulating spacers on the alumin-
gised which provides the gate current for the triac
ium partition as well as the 5V regulator. The triac is mounted on a to turn on. Using a reed relay in this way the i.c.'s are
tag strip, part of the mains transformer. completely isolated from the mains.
238
 PRACTICAL
IN NEXT MONTH'S WIRELESS

'Student"
OSCILLOSCOPE
Simple build. Inexpensive.
to One
assembly board. Specially designed for
students and all constructors who want an
all -transistor 'scope for displaying simple
waveforms. e

MINI COMMUNICATIONS
plus RECEIVER

Details of a new series of

articles, for readers who rr
want to get started in
construction of simple
radio and electronics
projects.

l
The "Mini -Comm" is just 8 4z .: 4in.
and yet completely self-contained. Five
transistors plus an audio module permit
reception of AM, SSB and CW signals on
the short wave bands.

DON'T MISS ANY ISSUE OF

PRACTICAL WIRELESS
AUGUST ISSUE ON SALE JULY 6th
T
239

www.americanradiohistory.com
 THE use of electronic devices to modify the sound
of an electric guitar has become very popular
in recent years, and the equipment of a
guitarist often includes such devices as echo
chambers, `fuzz" boxes and `wah-wah' pedals. This
article describes a tremolo generator which can be
used not only with electric guitars but also with most
other electronic instruments.

REQUIREMENTS
To add tremolo to a musical sound it is necessary
to vary the loudness of the sound repeatedly at a
very low frequency. In the terminology of electronics,
this process is called amplitude modulation.
Figure 1 shows a block diagram of the tremolo
generator. The input signal coming from the guitar
has a more or less constant amplitude. The tremolo
signal is generated by a low -frequency oscillator,
whose output frequency and amplitude can be
varied by means of foot pedals. The input and
tremolo signals are fed into an amplitude modulator,
whose output consists of the input signal with an
amplitude which varies at the frequency of the
tremolo signal.
Figure 2 shows oscilloscope traces of the signals
involved. The input signal (a) is, in this case a, 400Hz
wave generated by an audio signal generator. The
tremolo signal (b) is a signal of much lower fre-
quency, about 8Hz. The output signal (c) consists of
the 400Hz input modulated at 8Hz.

CIRCUIT DESCRIPTION
The circuit diagram is shown in Fig. 3. It is easier
to understand the circuit if the various sections are
considered separately.

.t 'tet.lt!
ttttlirttt.'ante... It.tt.t.ttn,t...w.r..

240
 for
GI1ITRR
gyrator
ORGANS
Oscillator
The oscillator is required to produce a reasonably
sinusoidal output at very low frequencies, from about
1Hz to 10Hz, and the usual circuit for this purpose
is the Wien bridge oscillator. In Fig. 3 transistors
Trl and Tr2 form a Wien bridge oscillator whose
frequency is determined by resistors VR1+R3,
VR2+R4, and capacitors C2, C3. The frequency can
be varied over the required range by varying VR1
and VR2, which are ganged.
This type of circuit requires an amplitude con-
trolling device to keep the output amplitude at a
level low enough to avoid saturation of the tran-
sistors; without this the output increases to a point
where severe distortion occurs. The usual ampli-
tude control device is a thermistor, which can be
R. MORGAN expensive, but by suitable modification of the circuit
it is possible to use a much cheaper device, namely
a 6V bulb LP1.
The output of the oscillator is fed into a potentio-
meter, VR4, the setting of which determines how
much of the oscillator output is fed into the next
stage. Consequently VR4 acts as a modulation depth
control.
Modulator
The musical signal from the guitar is fed into Tr3
and amplified. The degree of amplification depends
on the current through Tr3 and if this current is
varied the amplitude of the output from Tr3 is also
Fig. 1. Block diagram of the stages comprising the tremolo generator. varied. The current through Tr3 is controlled by Tr4,
so that when the oscillator signal is fed into Tr4, the
current through Tr3 varies at the same frequency
as the oscillator signal. Consequently the amplitude
Fig. 2(a) left, shows an Input signal of 400Hz from a signal generator of the output from Tr3 also varies at the frequency
while 2(b), centre, is a much lower frequency signal from the oscillator of the oscillator signal. The output from Tr3 is there-
in the tremolo generator. The two signals are fed to a modulator stage fore the musical signal modulated at the frequency
producing the signal shown In 2(c), right.
of the oscillator.

241
 R1 Tr2 R6 R8 R10 R12
5.6k 2N3903 JK1 1.2k 1.5k 5.6k 39k
S1A Input
S1B
Tr3
Tr1
C3 10pF
IIv C5 BC109
C6
BC 109 2pF 01pF
VR2
Tr 5
2N3903
0
BY1
9V
0 C2
(see text) C9
1000
pF
BY2
Cl 10pF R4 1k R7 9V
1000 1.2k
pF LP1
VR1 C7
(see text) 40-60mA VR4 C8 JK2
Frequency 1p F
470 R13 2p F Output
Tr4
BC109 10k
mplitude C4 'I
R2 R3 VR3 R5 470yF R9 R11 R14
1.8k 1k 470 150 470 5.6k 1k

1
I N 07161

Fig. 3. Complete circuit diagram of the tremolo generator. Note that

separate batteries are employed to avoid using expensive decoupling
Output stage
components. The modulator output is at a high impedance and
suitable for feeding directly into amplifiers with a
high impedance input, i.e. all valve amplifiers and

* components list most transistor amplifiers. However, some transistor

amplifiers have low -impedance inputs and if the
modulator is used with such an amplifier an
impedance -conversion stage is needed. The addition
Resistors
of such a stage makes the output suitable for all
R1 5.6k2 R6 1.2k0 R11 5.6k2
amplifiers, whether of high or low impedance, and
R2 1-8k2 R7 1.21(2 R12 39kO
there are certain other advantages such as a reduced
R3 1k0 R8 1 5kí2 R13 10k2 level of mains hum. The output stage in the present
R4 1k2 R9 4700 1 kit R14 design is an emitter-follower formed by Tr5.
R5 1500 5.6k0
R10
All resistors -1W 10º Power supply
VR1 50k0 linear VR3 4702 pre-set If several parts of a circuit are fed from one power
VR2 50k2 linear VR4 4700 linear
See text for further information on potentiometers
supply, there is a danger of unwanted interaction
between one part of the circuit and another, due to
Capacitors voltage variations, unless the supply is de -coupled
Cl 1000pF C4 47012F C7 1,uF (poly) by means of a resistor and capacitor. When a circuit
C2 10pF C5 21LF (poly) C8 21aF (poly) is designed to run at very low frequencies, as is the
C3 10pF C6 0.114F C9 1000p F case here, the de -coupling capacitor has to be very
All 12V or more working voltage large and therefore very expensive. A much cheaper
solution is to use separate batteries for each part of
Semiconductors the circuit. In the present design two batteries are
Tr1 BC109 Tr3 BC109 Tr5 2N3903 used, one for the oscillator and the other for the
Tr2 2N3903 Tr4 BC109 rest of the circuit.
Miscellaneous
Switch S1, double pole onloff. Jacks (2). Lamp CONSTRUCTION
LP1, 6V 40-60mA, with holder. Batteries PP9 or The electronics are built on a piece of 0.1in.
similar (2). Veroboard 12 x 24 in. (minimum) 0.1 in. matrix Veroboard, 1138 X 334in. A suggested layout
matrix, and pins. Metal for casework.
is shown in Fig. 4, but the layout is by no means
Meccano Parts
critical and can be altered if necessary to suit com-
ponents of different sizes and shapes. Constructors
Name Part No. No. Off who are not used to building on 0.1in. Veroboard
Axle Rod 4 in. 15b 3 should take care to avoid bridging between the
Axle Rod 3 in. 16b 1 copper strips, by avoiding the use of too much solder.
Axle Rod 2 In. 17 1 The two sections of the circuit are almost com-
Pinion e x ,'- in. 25 2 pletely separated electrically by severing all the
Gear wheel 11 in. 27 2
Nuts and bolts 37 1 pkt.
copper strips where indicated, except for the negative
Double angle strip 24- x ; in. 48a 4
rail, using a Vero spot cutter or a lain drill, or
Slotted strip 51- in. 55 4
alternatively, with a sharp knife. The transistor
Collar and screw 59 7 leads are rather short and constructors who are
Couplings 63 3 inexperienced in soldering are advised to hold the
Plates 5; x 24 in. 70 2 leads with a pair of fine -nosed pliers during soldering,
Sprocket chain 94 1 at a point between the solder joint and the body of
Sprocket wheel a in. 96a 2 the transistor.
Belicranks 128 4 Care should be taken to connect the input and
output jack sockets correctly, with the negative rail to
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 Y- To BY1 + the socket contact which touches the outer conductor
A BCOEFG I 1KLMKOPOA S1U WKYZA'B'C:0'E'F'6'11'1' of the jack plug. If a mistake is made in this, an
(rotor) embarrassing amount of hum may be induced.
Potentiometers VR1 and VR2 are ganged linear
To VR2 controls. While ordinary carbon potentiometers are
satisfactory, it is preferable to use wire -wound
(rotor) potentiometers because they have a much longer life
10
To VR1 and are less liable to noise. Ganged wire -wound
controls are not easy to obtain, and for that reason
the present design uses two ordinary single
15
potentiometers with their spindles connected to-
gether. The mechanical details of this linkage using
`HR2 Tri Meccano parts are shown in Fig. 5a. Because the two
20
controls are "back to back", the connections may
appear to be a little unusual, but if Fig. 5a is
25
followed there should be no difficulty.
The mechanical linkages between the foot pedals
R
and the controls are worth considering is some detail.
Fit flat plate (No.7O)
on top of pedal /m 48a

10807181

55 55

To VR4 48a

(rotor)

C4
_f

To JK1

r"(11312- (tip)
R6

r C5

Tocircuit To circuit
board board

27

Tr5
14
c

C8
VR4

---
To JK2
63
25

(tip) U/50
Q/52
To circuit
board
H/52 ) (b) 10807191
01107171 To BY2 +
Fig. (5a), top, shows the assembly of the Meccano parts and potentio-
Fig. 4: Layout of the circuit board. Breaks in copper rails are best made meters comprising the tremo/o frequency pedal.
before fitting components. Fig. (5b), bottom, is the pedal assembly for the tremolo depth control.

243

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1/2 plywood, 6112 x 21/2
TESTING AND ADJUSTMENT
When the construction has been completed, and
2BA countersunk the circuit checked carefully, the unit is ready for
l'
screws, long testing and adjustment. It is useful to have an
oscilloscope for this purpose, but it is not essential.
Because of the use of two batteries, each part of the
circuit can be tested separately.
1"x 1'
brass Oscillator
angle
The first job is to set the position of the frequency
Meccano pedal. Slacken off the grub -screws holding the short
axle axle between VR1 and VR2 and turn the spindles
(Na 15b)
of the potentiometers VR1 and VR2 to the minimum
resistance position. Push the foot pedal to the
extreme end of its movement, and tighten up the
grub screws. Check that the potentiometers rotate
smoothly when the pedal is moved. Leave the pedal
near the middle of its travel.
The next adjustment is to set the position of the
modulation depth pedal. Slacken off the grub-screw
Meccano collar w'th screw (No 59) soldered to brass angle of the cogwheel which drives the spindle of VR4.
(repeat on other side of pedal). After soldering drill Rotate the spindle to bring the slider to the earthed
through the brass angle to clear the axle. end of the track. Push the foot pedal to the extreme
Fig. 6: Details of the foot pedals which were eventually fitted to the end of its movement, and tighten up the grub screw.
prototype unit.
Check the rotation of the potentiometer when the
It is not possible to rotate one's foot through more pedal is moved and once again leave the pedal near
than about 60° without discomfort, while an ordinary the middle of its travel.
potentiometer can rotate through about 300°. In the Connect the oscillator battery (not the modulator
case of VR1 and VR2 a variation in resistance from ends of VR4. Set the timebase of the oscilloscope to
zero to about 10kí2 is required and this can be a slow scan (about one trace per second if possible)
achieved simply by using one end of the track of a and the input sensitivity to about 1 volt for full
50ká2 potentiometer. In the case of VR4 it is necessary deflection. If an oscilloscope is not available, put the
to use almost all the available rotation of the unit in a partially darkened room in a position where
potentiometer so a 4 to 1 gear ratio is needed be- the lamp LP1 can be seen easily.
tween the pedal and the control spindle. Meccano Connect the oscillator battery (not the modulator
provides a simple and cheap way of building the battery) and switch on. Adjust the preset potentio-
linkage, and a suggested arrangement is shown in meter VR3 until the circuit starts oscillating, as
Fig. 5b. evidenced by the trace on the oscilloscope or by a
From experience it was found that a sturdier pedal dull pulsating glow in the lamp LP1. Move the
assembly was desirable and two were constructed, frequency pedal to bring VR1 and VR2 to a high-
as in Fig. 6. They were each covered with corrugated resistance position. The frequency should drop to
rubber sheet. about 1Hz or less. If the circuit stops oscillating,
A piece of equipment of this sort
is subjected to a certain amount of
rough treatment, and it is important
to build a strong framework cap-
able of withstanding abuse. A sug-
gested design of framework is
shown in Fig. 7.
The circuit board can be fixed
with spacers to the back of the
case. The on/off switch and the
input and output sockets are fixed
to the left-hand side panel. The two
batteries are held in place by a
metal bracket.

A view of the partially assembled casework

showing the circuit board mounted along the
back with input and output jacks and on/off
switch at the iefthand side, The two batteries
are located by the partition at the right. Pedal
movement is restricted by the pedal housing, if
constructed as In Fig. 7.
244
 10N 07211

5 /4

Material swg. durai or

16
steel.
When cutting allow
for bends.

Aperture for leads

from circuitboard
to pedal controlrols

Fig. 7: Details of the casework housing the tremolo generator.

re -adjust VR3. Gradually raise the frequency by easily be prevented by connecting a resistor of a
means of the frequency pedal and check that the few kilohms in series with the input, between the
oscillator works correctly over the required range input jack and C5.
of frequency; if it shows any sign of stopping, re-
adjust VR3. The ideal position for VR3 is one in OPERATION
which the oscillation is just able to continue over the
whole range of frequency, but the setting is not very Connect both batteries, the guitar and the
critical. Finally, switch off. amplifier. Switch on and adjust the positions of the
pedals while playing long chords. The effect of the
tremolo generator on the sound should now be
Modulator apparent.
Disconnect the oscillator battery and connect the The guitarist may like to try the tremolo effect
modulator battery. Plug the guitar lead into the in conjunction with other devices. It appears to be
input socket and plug the output into the guitar particularly effective when used with a `fuzz' box.
amplifier. Switch on and check that the volume is It seems that better results are obtained when the
satisfactory and that there is no distortion of the `fuzz' box is placed between the guitar and the
sound. If all is well, no further adjustment is needed. tremolo generator, rather than between the tremolo
If there is noticeable distortion, it is probably due generator and the amplifier, but this is a matter for
to overloading of the modulator, and this can most experiment.
245

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 3-BAND TRANSMITTER
PART Z F.G.RAYER G3OGR
THOUGH this VFO is particularly intended for Components in the VFO stage are enclosed in a
use with the transmitter described last month metal box on the chassis and this complete screening
it can be employed for the frequency control avoids any difficulties from stray feedback. The whole
of any similar transmitter. The VFO has a straight- VFO is in turn enclosed in a metal box or case.
forward circuit which can give reliable and excellent A 6BH6, V2, is a buffer -amplifier which also
results. frequency doubles for working on 7MHz and 14MHz.
On 3.5MHz resistor R6 forms the anode load. Output
CIRCUIT to the transmitter is by a co -axial lead plugged into
the socket which is provided on the transmitter. The
Fig. 1 is the circuit which uses a 6C4 as 'a Clapp latter also supplies power for the VFO. When work-
oscillator, the HT to this stage being regulated by ing on 14MHz, the crystal oscillator stage of the
the OA2 voltage regulator. The valve capacitances transmitter acts as a second doubler.
are shunted by the large value capacitors C2, C3, and Coil L1 and capacitor VC1 tune 3500-3800kHz and
C4, so this type of circuit proves to be stable and output frequencies are fundamental or doubled
trouble-free. which makes the VFO calibration easy.
R3 10k HT +250V
1,5
VR
OA 2
1L2
2,4,7
r
R547k 8 40/20

SW1--
j2000pF 1,5 50pF
V1
6C4
6 Fig. 1: Circuit of the two valve variable
frequency oscillator. The power for the
VFO is taken from the main transmitter,
described last month. Components
associated with the 6C4 oscillator valve
are shown within the dotted enclosure.
C5

100pF i C7
2000pF

-ve
VC1
75pF

246

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 VFO BOX
The variable frequency oscillator coil Ll and
* components list
associated components are completely enclosed in a
box, Fig. 2 which is very easily made from "universal Resistors
chassis" members. A flanged member 8 x 3in. is R1 47kl t +W R3 10kS2 3W R5 47k12 1W
taken and a V-shaped notch is cut in each flange 2in. R2 2.2kQ f W R4 100k12 4-W R6 4.7k9 1W
from the end. A right-angled bend can now be made Capacitors
2in. from each end. A sharp bend is best obtained Cl 200pF 1% SM C6 0 25µF 350V
by holding the member firmly on a piece of wood C2 1000pF 1% SM C7 2000pF disc
just large enough to rest between the flanges, and C3 1000pF 1 SM C8 50pF SM
with one edge level with the bending line. This gives C4 2000pF disc TC1 30pF trimmer
a U-shaped piece 2in. high and 4in. wide. The front C5 100pF SM VC1 75pF variable
is closed by attaching a 4 x 2in. flanged plate with
four bolts. After all assembly is finished, a flat back Valves
V1 6C4 V2 6BH6 VR 0A2
plate 4 x 2in. is fixed on with self-tapping screws.
Tuning capacitor VC1 is mounted on the front Miscellaneous
flanged plate as in Fig. 2 and the ball drive is put Valveholders B7G (3) with screens (2). Ball drive,
on. Its lug is held with a long bolt with spacer, or knobs. Single pole 2 way switch. Formers, fin. dia.
extra nuts. with cores, (2) (Denco). RFC 1, miniature choke
Trimmer TC1 is fixed on a small bracket under a 2.5mH. VFO box: Universal chassis member, 8 x
hole, so that it can be adjusted from above with a 3in., flat plate 4 x 2in., flanged plate 4 x 2in. Panel:
screwdriver. Tag-strips are used to anchor R2, C5 plate 8 x 7in. Chassis: plate 8 x 4in. Case: flanged
plates 8 x 4in. (2) 7 x 4in. (2) Home Radio.
and RFC1. The coil Ll is positioned as shown, with
its core adjusting screw projecting from the top of
the box.
Wiring and components in the box should all be standard. This will give calibration marks at 3.5,
rigid. 3.6, 3.7 and 3.8MHz. Tuning the receiver to the
second harmonic of the VFO will give 3.55MHz (at
6.3V 7.1MHz) and so on, while the fourth harmonic will
give calibration for the 20m band. When the VFO is
RFC7/, being calibrated, or is in use with a transmitter, the
V1 en higher frequency bands are direct multiples of the
o6CH !Qn1
HT
MC ..:® 4111
MC

=ä 3
3.5MHz band frequencies, so working with and
marking the scales is very straightforward.

CHASSIS AND CASE

TC1
pull V1 The main chassis is a universal chassis flanged
member 8 x 4in. This allows similar members to be
^ used for the top and bottom of the VFO case, with
7 x 4in. flanged members for the sides. The front is a

o; v e
flat plate 8 x 7in.

e Front plate
with flange
Ball drive

Fig. 2: Layout and wiring of components within the separate oscillator

box.

Coil Ll is wound on a cored former, 12in. in

diameter and 114in. long, with 30 turns of 26swg
enamelled wire, closewound. The winding is started
as near to the top or pin end of the former as
possible. The former can be lightly smeared with a
suitable adhesive (Denfix) before winding. The end
is secured with cotton and adhesive.
The VFO can be tested by applying heater and HT
voltages (about 150V) and adjusting TC1 and Ll
for suitable coverage. With VC1 almost fully closed,
Ll core is rotated to obtain 3.5MHz. VC1 is then
set almost fully open, and TC1 is adjusted for
3.8MHz. One adjustment modifies the other, so this
needs to be repeated several times. Sufficient coup-
ling to a receiver is obtained by placing the aerial
lead near the VFO.
Final calibration should be with the aid of a
100kHz crystal marker or equally accurate frequency Rear view of VFO shows position of oscillator stage on main chassis.
247

www.americanradiohistory.com
 Fig. 3: Details of layout on top of main chassis.
The oscillator can be checked and roughly 0\
calibrated before the box is fitted to the top of Cut away
L1 TC1 QJ
the chassis. RF output and power supply wires
pass down through a hole in the chassis.

Cursor

+250V
6.3V Common earth

To VFO box
R2 MC

C5 Vi p,n4 VR
MC
o0A2
Fig. 4: Underneath the chassis showing the
wiring of the buffermultiplier stage and volt-
age regulator for the oscillator stage. The co-
R3
axial lead, bottom left, to the transmitter must
be as short as possible. Power supply leads are
taken to a 3 -pin plug matching the socket on
the transmitter.

Co -axial
lead

The long flanges of the chassis member are first position is adjacent to the transmitter VFO input
cut away at each corner just sufficiently to allow socket, so a long co -axial lead is not required or
this item to fit inside the flanges of the members desirable. A long lead here may cause difficulty in
which form the sides of the case. The chassis is bolted resonating L2, or in securing adequate drive, due
so that its top surface is 2in. above the bottom edge to its capacitance and possibly losses in the high
of the 8 x lin. panel plate. Voltage regulator VR and impedance anode and grid circuits.
V2 are placed as in Fig. 3, and the wired VFO box L2 has 38 turns of 32swg enamelled wire close -
is bolted in this position and its back closed with the wound on a 12M. diameter former with adjustable
4 x 2in. plate. core. The winding should begin as near to the tagged
end of the former as possible.
The VFO should be tested before completing the
case. It was found stable when used without the
WIRING case, but the latter improves screening and rigidity.
When the case is assembled, a short screwdriver
Fig. 4 shows components and wiring under the is necessary to reach Ll, L2 and TC1.
chassis, with leads passing through a hole for heater, To assemble the case, put the side members with
regulated HT and the connection from C5 to the their flanges in the slots provided. The bottom and
grid of V2. top can then be put into place, and are bolted to the
A tag strip holds flexible leads for 6.3V, 250V and sides. The case is chècked for squareness, and the
common chassis return. These three leads can be panel is correctly positioned. Holes for self-tapping
about 18in. long and they are soldered to the pins screws are then drilled through the panel and side
of the 3-way plug, which fits the transmitter power flanges, so that the panel can be secured. It is best
outlet. Power switching of the VFO is controlled by to drill both panel and flange with a bit suitable for
the CW/AM/OFF/NET switch on the transmitter. the self -tapping screws to hold, then use a larger
The VFO output lead is about 9in. of low -loss co- bit, on the panel holes only for clearance.
axial cable, passing through a grommet in the front The flanges of the member forming the chassis are
panel and anchored at a tag strip. The VFO output bolted to the sides of the case.
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www.americanradiohistory.com
USING THE VFO the VFO, two methods were employed to spread the
For operation on 80m, VFO, driver and PA switches tuning on the HF bands. These may be of interest,
are all set to the 80m position. With the transmitter though they were not used in the completed VFO.
control switch at "Net" grid current should be shown The method shown in Fig. 5 gives coverage of
by the transmitter meter and the carrier should be 3.5-3.8MHz on one range for 80m. On the other
range the VFO tunes from 3.5-3.6MHz, giving
coverage of 7.0-7.2MHz and 14.0-14.4MHz with
almost the full 180 -degrees rotation of the tuning
capacitor.
With the switch at 80m, VC1, VC2 and VC3 are all
in parallel, forming a 7SpF variable tuning capacitor,
with TC1 and the 200pF capacitor as before.
When the switch is on 40/20, TC2 with its parallel
fixed capacitor substitute for VC2 and VC3 and
coverage is restricted to that of VC1, that is 3.5-
3.6MHz, giving actual ranges of 7.0-7.2MHz and
14.0-14.4MHz.

Fig. 5: Modified oscillator circuit to Improve bandspread coverage on

the higher frequency bands.

found on a receiver at the VFO frequency. The

transmitter driver stage screen grid potentiometer
will need to be turned back considerably to keep
grid current down to the correct level.
For working on 40m, place the VFO switch at
40/20m and the transmitter switches at 40m. L2
may need adjusting as mentioned for 20m.
When first testing the VFO on 20m, tune to about
14.2MHz. Set the VFO switch at 40/20m and both
transmitter switches at 20m. With the control switch
at "Net" rotate the core of L2 for maximum grid
current as shown by the transmitter meter. On all
bands tune the PA grid for maximum grid current,
adjusting this to a suitable level with the drive
potentiometer.
A closer look at the VFO dial calibration.
CALIBRATION
A Jackson miniature 25pF 3 -gang capacitor was
The scales are marked so that the higher frequency used. TC2 is adjusted so that 3.5MHz falls on the
bands are direct multiples of the low frequency same tuning position, with the switch at 80m or
band. So 3.5MHz is also 7.0MHz and 14.0MHz. As 40/20m. The 80m range has to be individually cali-
mentioned this greatly simplifies calibration. brated. The 20m range is the second harmonic of
the 40m range.
Fig. 6 shows a modification used for some con-
siderable time in conjunction with an all -band trans-
mitter. With the switch placing Ll in circuit, TC1 is
adjusted for coverage of 1.75-2.0MHz. This is for
Top Band (160m) and 80m, the 1.75-1.9MHz portion
of the band being doubled for 3.5-3 8MHz. Ll is
60 turns of 36swg enamelled wire, closewound on a
12in. diameter cored former.
When the switch places L2 in circuit, coverage is
from 7.0-7.2MHz. This gives operation at the
fundamental frequency of 7.0-7.1MHz for 40m. For
20m, 7.0-7.2MHz covers 14.0-14.4MHz, with
doubling. This same VFO band provides 21.0-
21.4MHz for 15m and 28.0-28.8MHz for 10m.
Where the transmitter has few frequency multi-
plying stages this arrangement is very useful indeed.
When the transmitter covers all bands with the
Fig. 6: Suggested circuit to give full scale coverage on all bands, minimum of circuits, it is helpful to fit a 4-way
1.8-28MHz. switch for V2 in the VFO. In addition to the untuned
load, coils for 3.5MHz, 7MHz and 14MHz may then
With this method of covering higher frequency be selected, giving a choice of VFO outputs, with
bands only a smaller part of the tuning spread is only tripling required to reach 21MHz, or doubling
used for 40m and 20m. During experimental use of for 28MHz.
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GOING BACK ...
5014°
170 COLIN RICHES
ARTHUR DOW
Following our review in the April issue of the
extensive collection of vintage wireless equip-
ment belonging to George Weston of Auckland,
New Zealand, we received a copy of a letter sent to
Mr. Weston by Mr. W. W. Barnes, G2FI, of Wadhurst
in Sussex, who began his career in wireless in 1917
when he was with the Royal Flying Corp. He rightly
congratulates Mr. Weston for having stuck to his
task of gathering together so much ancient gear in
a part of the world where the amount of such
equipment must be very limited.
Mr. Barnes joined the Philips Company in 1926
and stayed with them for many years, mainly in their
Servicing Department, and thus was able to offer
some additional information on the 2510 and 2515
receivers that we pictured in the April issue. These
sets were made at Eindhoven in Holland but when
sent to England were fitted with Mullard valves and
the type numbers changed to 2511 and 2516 respec- George Tagg seen here at St. John's, Newfoundland, is still active on
tively! Needless confusion does not seem to be the the air as GBIX.
prerogative of the modern society! The 2511 was the
first domestic receiver having two HF stages to app- Remarkably enough the best DX included contacts
ear on the English market and, according to Mr. with the station at Pembroke Dock. George recounts
Barnes, was far ahead if its time. It was built 'like taking photographs of Alcock and Brown before their
a battleship' and reputedly was just as heavy! epoch-making Transatlantic flight and also making
Obviously the forerunner to the AR88! special transmissions and test signals for them
Mr. Barnes recalls feeding the output of a 2511 while they prepared their equipment.
into a pair of PX4's which fed a mains energised
18in. loudspeaker. The speaker and its power supply
alone weighed 481bs.! We understand that the cur-
eartp CourteStN
rent copy of the Philips News Sheet refers to a letter Our collection of photographs of 'very ancient
from a cost yner saying his 2515 is still in use and stations' has been swelled by a contribution from
functioning perfectly. Mr. Barnes built his own two -
Mr. S. D. Mason of Torquay whose station was active
HF -stage receiver in 1922 from a design published in 1910! It doesn't take much work on the office
in the old 'Modern Wireless'. However it was unstable slide rule to realise that Mr. Mason is now a proud
to the extent that the coils had to be wound with 80 years of age. In those early days he was located
resistance wire to 'hold it down'. at Forest Gate in London and his call sign was just
a simple 5SV. The preamble to his licence ran `To
all whom these presents shall come, the Post Master
errangattanttt ROE General the Rt. Hon. Herbert Samuel sends greet-
Another old-timer from the ranks of the amateur ings ... etc.' ... obviously a unique document one
fraternity is George Tagg, G8IX, now of Stoke-on- would be very happy to possess.
Trent, who has been good enough to trust us with the Morse and telephony were both used at 5SV to
original negatives and photographs of the wireless work other stations in the Ilford and Barking areas
gear that he operated over fifty years ago, in 1919/20 but seemingly the ship's operators in the Royal
to be precise. He was then a Leading Telegraphist Albert Docks were not very favourably impressed
at HM Wireless Telegraphy station at Mount Pearl, by the virtually untuned spark gap at 5SV! The
St. John's, Newfoundland and the equipment in use aerial was a twin wire inverted L but only 30ft. long
included a Model L receiver and a Poulsen Arc which must have been very short compared with the
transmitter. (If anyone has any information on this wavelength in use at the time.
receiver we would be glad to hear from them.) At the beginning of the First World War all Mr.
250

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TRANSISTORS BY ELECTROLYTIC CAPACITORS Polycarbonate
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50167 11p; BC168 9p; BC169 lip 11
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50177 111p; BC178 19p; 50179 81p: I
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RESISTORS 10%, 5%, 2%
Other semiconductor. ,r.l. Pores, Trirranr. Range talitre 1109 10 fo 06 100 .op
AC128 17p: AF117 85p osilobir i.ec note below )

BFY61 19p 1/20W 62 t1 -220K Cl BIS 9 8 7.6

Full lists and technical data will be found
( 118W 4.7 fl -470K (1 224 1 et
0.9
0.71
0.71
)n 1/4W 4.7 CI -10111-1 212 1
Catalogue No. 6. See also amendments list. 1/2W 4.7I1 -10M 6 224 1.2 1 0.8
lW 47 6-10M 6 212 2-D 8 1.0
MO 1/2W 1o6-1M6 624 4 8 8 sett
WW IW 0.22 C3-8.9 212 7 6
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Values:
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ZENER DIODES full range E24 values: 400mW: 2.7v to and their decades.
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(type 266F) 4p.
IMPORl'ANT. We regret chat cher. rubatantiol priez in
erra e have occurredarme
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by Il irvhmau u. J \ rat ink Rotary carbon track, double wiper

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 MANUFACTURERS OF ELECTRONIC AND
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 Would you spend
an hour a day
to earn more money
in Electronics -
Television - Radio?
If you're willing to give up one hour or more a day
we can help you get into the lucrative growth industries of
electronics, television, radio.
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Once you've got the qualifications you need, you'll be in a
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which exist today in all fields of electronics - in television
(colour and black/white) and in radio. (We teach you the
theory and practice of valve and transistor portable cir-
The spark gap at 5SV can be seen on the top shelf under the copper
cuits while you build your own 5 valve receiver, transistor
strip helix coil which 'tuned' the transmitter. Below is the 2 -valve portable and high grade test instruments).
transmitter consisting of an oscillator and modulator. With ICS you study at home - at your own pace, when
you choose, in the time you've got available. Your ICS
Mason's equipment was impounded and he found tutors will give you all the help and encouragement you
himself with the Royal Naval Air Service at the need to pass any exams you want to take.
White City in London, very close to the present site
of the BBC TV service. After operating WT equip- Don't waste another day. Take your first step now
ment from airships based at near-by Wormwood towards a better paid, more assured future. Send for your
Scrubbs (another famous name!) 5SV passed to FREE Careers Guide today.
Manston for flying training and finished up with No. 3
Wing in France. Unfortunately Mr. Mason is no
longer on the air, which is rather unusual. Generally
'CSyour key to the door
of opportunity
Tick or state subject of interest and post to:
the bug, having bitten, doesn't let go! At least not International Correspondence Schools, Dept. 232 P.
for long! Intertext House, Stewarts Road, London SWS 4UJ.

Subject of interest

Society of Engineers Graduateship (Electrical Engineering)

C & G Telecommunications Technicians Certificates
C & G Electrical Installation Work
C & G Certificate in Technical Communication Techniques
MPT General Certificate in Radio Telegraphy
Audio, Radio & TV Engineering & Servicing
Electronic Engineering, Maintenance, Engineering
systems, Instrumentation & Control systems
Computer Engineering and Technology
Electrical Engineering, Installations, Contracting, Appliances
Self-build radio courses

Name

Address

Occupation AgeI
Accredited by the Council for the Accreditation of Correspondence Colleges a r
253

www.americanradiohistory.com
 9023 Voice of Iran in English at 2000.
9690 R. Pakistan with news in English at 1815.
9745 'HCJB, Quito, Ecuador, DX Partyline at 0900.
10040 Voice of Vietnam, Hanoi, news in English.
15415 R. Kuwait in English at 1630.
17895 R. Portugal in English at 1345.

SHORT WAVE DX
J Ian Gordon of Rubery, Birmingham has managed
to extract signals from the following stations out of
the central heating radiator which he use as an
by MALCOLM CONNAH aerial and coax them into his Codar CR70A receiver:
9005 R. Iran in English at 2015.
APART from the gems of information which can 9570 R. Australia at 0730.
be gleaned from this monthly page, the best 9655 R. Damascus, Syria in English at 2050.
sources of DX information and station news 9670 Adventist World Radio at 0940.
are the DX programmes broadcast by many stations 9745 R. Baghdad, Iraq in English at 1950.
throughout the World. 11675 R. Pakistan in English at 2035.
The following list shows the times at which some 11710 RAE, Argentina, s/on at 2300.
of the more popular programmes are broadcast. In 11765 R. Australia, DXers Calling (Sun.), 0730.
all cases the broadcasts are in English. 15012 Voice of Vietnam, Hanoi in English at 1815.
Australia "DXers Calling" is broadcast during the 17885 R. Japan, s/on at 0800 in English.
English transmissions on Saturday at 2130; Sunday at Shaun O' Sullivan of Keynsham (yes that's K -E -Y -
0430, 0730, 1300 and 1530 and on Monday at 0215. N-S -H -A -M of Radio Luxemburg fame), Bristol, has
Ecuador HCJB in Quito broadcasts its "DX Party a one valve `H.A.C.' t.r.f. receiver and a two tran-
Line" programme on Monday at 0030, Tuesday at sistor amplifier connected to a 100 foot long-wire
0300 and 1930 and on Wednesday at 0900. antenna. This combination enabled him to hear:
Great Britain The BBC's "World Radio Club" 5930 Radio Prague, Czechoslovakia in English at
programme is broadcast over the normal World 2135.
Service outlets at the following times: Sunday at 5995 Voice of America in English at 2040.
0815, Wednesday at 1330, Thursday at 2030 and 6160 Radio Sofia, Bulgaria in English at 2135.
Friday at 2345. 6190 Vatican Radio in English at 2100.
Portugal Adventist World Radio transmit a 7090 Radio Tirana, Albania in English at 2040.
programme of DX News compiled by our own World 7100 Radio Moscow, USSR at 2110.
DX Club at 0935 on Sundays on 9670kHz. Dave Gregory of Plymouth in Devon has a Bendix
Sweden The "Sweden Calling DXers" programme RA -1 aircraft receiver and an 80 foot long-wire
is 25 years old this year but can be referred to as antenna, his log for the month included:
the "grandaddy" of DX programmes. The programme 7100 R. Pakistan in English at 2200.
is broadcast every Tuesday and takes up half an 9125 Test transmission from Panama City at 0035.
hour of the normal English programmes. 9535 Swiss B.C., Berne in English at 1530.
Switzerland "Swiss Shortwave Merry -go -Round" is 9725 Kol Israel noted at 2140.
broadcast in all the English transmissions of the 9770 R. Baghdad, Iraq at 2045.
Swiss B.C. on the 2nd and 4th Saturdays of the 11640 R. Bangladesh in English at 1800.
month. 11755 AIR, Delhi in English at 2230.
11805 Radio Finland noted at 1910.
Readers' Logs 11880 Radio Sweden in English at 1230.
The first item in this section this month comes 11900 RSA, South Africa in English at 1115.
from John Godwin of Rugeley in Staffordshire. John 15175 Radio Norway noted at 2200.
reports hearing Radio New Zealand between 0600
and 0800 on 11780kHz on his pre-war HRO receiver
and "Joystick" antenna. DX Clubs
The transmitter power of Radio New Zealand is The Youth DX Club International (YDXCI) which
only 712kW and reception in this country is fairly was mentioned in this column last month has
difficult. Well done John! announced that the maximum age of its members
Alexander Morton of Franilingham in Suffolk has will be 17 years. The membership fee is £1.20
two receivers, a Bush AC2, 5 valve domestic and a which includes the cost of sending the magazine to
VEF-204 10 transistor portable. His log included: any country. The address for membership enquiries
5920 R. Kiev, in English at 1930. is YDXCI, Bartletts, Culmstock, Cullompton, Devon.
254

www.americanradiohistory.com
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Valve line up: -2 x ECL88 Triode Pentode.. 1 x EZSO Beautifully made teak Bnieh enclouure with most list free with kit or send 18p pill. large S.A.E.
as rectifier. Two dual potentiometer are provided for attractive Tygan-Vynalr front. Size 16' high z 105' AMPLIFIER KIT .. 111.66 P. & P. 18p
bass and treble control, giving base and treble boost and wide z 6' deep. Fitted with E.M.I. Ceramic Magnet (Magnetic input components 39p extra)
cut. A dual volume control is used. Balance of the left and 13' z 8' baos unit, two H.F. tweeter units and POWER PACK KIT .. U SO P. A P. 99p
right hand channels can be adjusted by means of a sepa- crossover. Maximum power handling 10 watts. CABINET 88.30 P. A P. 39p
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output of 4 watts per channel (8 watts mono), into 3 ohm OUR PRICE 19.25 Carr. 70P Also available ready built and tested {28.10. Poet Free.
.peaken. Full negative feedback in a carefully calculated Cabinet Available Separately £4 96 Carr 65p Note TM above amplifier ts suitable for feeding (too mono
circuit, allows high volume levels to be used with negligible Also au allable in 8 ohms with EMI 13' x 8' hays moire.. into input. (e.g. mike, radio, fain record deck., etc.)
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Intermittent). Volume and tone controls. Chasm else only 7in. wide plated heavy gauge metal
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Fitted Insulated output terminals and pilot lamp indicator

If20 49' h. Incorporates ECC83,

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Hammer finish metal case overall size 8' x 35' x 25'. Supplied absolutsly Brand New completely wired and
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transformer and output trans-
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5112.3ohm 81.06, P. et P. 15p. 7 x 41n. 9 ohm 91.15, P. R P. .weaker. Separate volume control and now with improved
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8 x Sin. 3 ohm with high dux magnet 81.82, P. & P. 29p
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HIGH GRADE COPPER LAMINATE BOARDS 8" x 6' H.M.I. 13 x 8in. 3, 8 or 15 ohm with two inbuilt tweeter. wired and tested for only 86.60. P. A P. 35p.
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2 amps full wave. Size 3in. long x 311n. wide x lin. deep. Guitar models: 25w. 87.60 35w. 19.86. P. A P. 409 Suitable for magnetic or ceramic pickup tape mlc. etc
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GENERAL PURPOSE HIGH STABILITY specification.
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use with valve or transistor equipment. 9-18v.
"POLY PLANAR" WAVER -TYPE. WIDE RANGE A etyllehly finished
battery or from A.T. line 200/300v. Frequency ELECTRO -DYNAMIC SPEAKER monaural amplifier
response 15Hz-25KHz. Gain 28d13. Solid encap- Size 115" x 1411' z 1 /,' deep. Weight 19oz. Power with an output of
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many 1000's of British, U.B.A. European and Japanese app. 54 in. wide. Our price Up yd. length. P. & P. l5p input. for mike and
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8 Reference Encyclopedias for Electronic Engineers and and announcement.
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OUR PRICE 81 16, P. A P. 10p tested £18.10 P. d P. BOp.
Open 9-5.30 Monday to
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255

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SINCLAIR PROJECT 60 Beginner's Guide
Z50 £4.25
PZ5 £3.97
' \ ' L n4"
; ..vh0-'1 7.
.
to Colour
PZ6 £0-40 1 ,.v Television
Project 60
tuner £16.00 Stereo 60 E7.90 2nd Edition Gordon J. King
AFU £4.50 Amp £22.00
2000
Transformer for PZ8 £2.85
The reader is guided through the
PZ8 E6.60
EXECUTIVE CALCULATOR £50.00 TRANSCEIVERS principles of NTSC and PAL to
Due to warehouse clearance we have for
dis- an understanding of the method
PROJECT KIT £2.50 posal, few only Transreceivers No. 62 Mk. 2,a
60
Our extremely popular kit contains the extra made by Pye for the Navy and Army. Using
of operation of the PAL system
capacitors, din plugs and sockets, cable and fuse - total of 11 valves. I RF and 2 I.F. stages. A.V.C., from aerial to display tube. The
holder needed to complete Project 60. BFO, covering -5 Mcls to 10 Mc/s. (approx. 200
author, noted for his crisp and
I

to 30 metres) in two switched bands. Can be

IC RADIO CHIP TBA651 £2'10 used on RT or CW M.O. or Crystal. A very
The world's most advanced IC radio chip Con- good internal ATU made of a rotating silver lucid style, has completely re-
ning& RF Amp, oscillator, mixer, IF Amps,
wide wire coil, tunable over the complete range, vised this edition which will be
range AGC circuitry and voltage stabilizer. With suitable for aerials 4ft. to IOOft., internal P.U.
data £2.10. Send S.A.E. for free leaflet. A kit of for checking
for 12 volt D.C. A meter is fitted metal of immense value to all who wish
is available to etc. Housed in water-
resistors, capacitors and IF filters voltages. A.V.C. a

go with the chip for £1.75. proof case, approx. size 18' x 100' x 120'. re- to understand how colour tele-
Supplied in as new condition, being either
built by Army Signals or store -soiled new set. vision works.
8-DECS AND T-DECS in cartons two spare valves, circuit, price
telephone
£17.50, carriage £2. Suitable hand switch in 1973 208 pp, illustrated
S-DECS
T-DECS
£1.44
£2.00
£300
I/' with spring coil plus transmitter
handle. Modern. LI -50.
CRYSTAL CALIBRATOR No. 10. Range
0 408 00101 1 £1.95
it-DEC A on Har-
16 i1
carriers £1.20
; -f 500 kc/s. co 10 Mc/s., up to 30 Mc/s.
monics.
HT, 2 volts.70'
T. The
volts
can plug into Elements of
Power Socket on the 62 Trans -Receiverin which
SINCLAIR SUPER IC12
a
it was normally used with. Supplied good
50p.
used condition with circuit, £2.50, Post 50p.
Linear
or BRAND NEW IN CARTON, £5.00,
post. Microcircuits
ONLY £20\1V turned if items out of stock.
these
order or uncrossed P.O. asPlease add
cash with
All enquiries include S.A.E. Terms;will be re-
10% VAT T. D. Towers
Based on a series of articles

LOHNS RADIO written for Wireless World, the

book gives practical guidance on
Max. supply volts 28. Power 6 Watts rms. Com-
plete with free printed circuit board and 44 page 424 BRADFORD ROAD, the commercially available linear
Instruction book. BATLEY, YORKS. microcircuit devices, and on the
SWANLEY IC TOMORROW £2'50 handling of these sensitive cir-
The World's most powerful IC amplifier. Similar Phone: Batley 7732 cuits within an assembly. The
to the above but operates at 35 volts max. supply
and gives 12 Watts rms output. Manufactured for emphasis throughout is on
us by a leading semiconductor company. Supplied
with our Instructions and a 8 month guarantee, applications and on the every-
but no printed circuit.
day problems of designing.
KITS FOR IC12 AND IC TOMORROW EX COMPUTER PC PANELS 1973 116 pp, illustrated
Except for the power kits end speakers, all Items 2 x 4 in. packed with semiconductors and
suit both Integrated circuits. cop quality resistors, capacitors, diodes etc. 0 592 00077 X £2.80
DELUXE KIT Guaranteed min. 35 transistors plus data.
nciudea all parts for the printed circuit and 10 boards S0p (9p)
volume, bass and treble controls needed to com-
plete the mono version £1.45. Stereo version with
balance control £3.30.
SPECIAL BARGAIN PACK Television
25 boards for Ll (25p).
BASIC KIT
Contains components for the P.C. board and Panels with 4 Power transistors sim 0C28
SOP (9p)
Engineers'
volume and simple tone controls. Mono version
£1.25. Stereo version with balance control £2.00.
POWER UNITS FOR THE IC12
ELECTROLYTICS Pocket Book
A set of components to construct a 28V 0.5 Amp I0,000µ 75v, 68,000µ I6v, 4} x 2 in. dia.,
powersupply suitable Sinclair PZ5 25,000µ 25v, 20,000µ 30v, 5,000µ 90v, 6th Edition
fully t£227. Also
7. 35,000µ I5v, 8,000µ 55v, 44. x 3 dia. 50p (I5p) Revised by P. J. McGoldrick
POWER KIT FOR IC TOMORROW I5,000µ I5v, I0,000µ 35v, 4} x 2 in. dia.
A set of components to construct a 35V 1 Amo 30p (10p), 2,000µ 25v wire ends I5p (5p). Extensively revised and updated,
power supply £297. for El50 (I5p)
12
LOUDSPEAKERS FOR THE IC12 the sixth edition of this popular
Specially chosen for the IC12. 5' 8 ohm £1.00. 8 BLACK TOGGLES dpst SOP (Op)
5'n 8' 8 ohm £1.45. 10' x 6' 15 ohm £2.27. 60p (8p)
book provides an essential sum-
250 MIXED CAPACITORS
PREAMPLIFIER KITS 60p (8p)
mary of all the basic facts, circuit
Type 1 for magnetic pickups, mica and tuners, 250MIXED RESISTORS
with 3 position equalization switch. Mono model techniques and technical data
LI.20. Stereo model £2 20. Type 2 for ceramic or ISOHI-STAB RESISTORS 60p (8p)
crystal pickups. Mono 60p. Stereo £1.20.
likely to be required for servicing
SEND S.A.E. FOR FREE LEAFLET ON KITS
200 SI PLANAR DIODES S0p (Sp)
either colour or monochrome
SUB. MIN. CO -AX PLUGS dr SKTS.
BATTERY ELIMINATOR BARGAIN £3.40 4 pairs 50p (5p) receivers.
Introducing the most 376 pp, illustrated
versatile battery REED RELAYS, MIXED 10 for 50p (5p) 1973
eliminator ever offered,
MICRO SWITCHES 8 for 50p (8p) 0 408 00102 X £2.50
with a high current
output that makes it ASSORTED RELAYS 8 for CI (I2p)
suitable for operating Obtainable through any bookseller
moat battery tape recor- MIN. GLASS NEONS 12 for 50p (5p)
ders, record players, or from the Publishers
cassette recorders and 10 WAY TERMINAL BLOCKS
shavers. Input 2001240V. 10 for 55p (5p)
Output voltage selected
by front panel switch Q -H BULBS 12v 55w SOP (5p)
The Butterworth
may be set to 3V, 4.5V, BV, 7.5V, 0V and 12V at
500 ma. Housed in a very strong; attractive, plastic
case and fully guaranteed for 12 months.
Postage and package for each item shown
in brackets.
Group
88 Kingsway, London
Please add 10% VAT to prices.
SWANLEY ELECTRONICS WC2B 6AB
32 Goldsel Rd., Swanley, Kent
KEYTRONICS Showroom: 4-5 Bell Yard,
Post 10p per item. Please add 10% extra to total
(Mail Order only) London WC2
coat of order for VAT. Official credit orders
welcome from schools etc. Full lists 10p post free. EARLS COURT ROAD
44
Mall order only. No callers please.
LONDON W8. 01-478 8499

256

www.americanradiohistory.com
 Andorra for the transmissions on 701kHz and to Sud
Radio, B.P.7 Andorra -la-Vieille, Andorra for those on
818kHz. Remember to include an International Reply
Coupon (obtainable from main Post Offices) to cover
return postage and to ensure a reply.
D. O. French (Stroud Green, London) is unable to
hear the religious broadcasts from Trans World
MEDIUM WAVE BROADCASTS Radio Monte Carlo on 1466kHz because of inter-
ference from the BBC Radio London station on
by CHARLES MOLLOY 1457kHz which transmits from Brookmans Park.
He expects TWR to increase power on 1466kHz from
BILL JARVIS (Luton) has received direct from 400kW. to 1000kW by the end of 1974. TWR will then
the BBC "20 BBC Local Radio Stations" which join the growing list of medium wave broadcasters
gives details of locations and power. that use powers of a megawatt or more. Others
R. Howard (East Runton) has sent the following include Radio Bucharest, Rumania on 1052kHz; El
log of BBC Local Radio Stations heard at his QTH Beida, Libya 1124kHz and Tripoli, Libya 1250kHz
in Norfolk-Radio Blackburn on 854kHz; Radio both of which are easily heard in the UK after dark;
Sheffield 1034kHz; Leeds 1106kHz; Newcastle -on - Batra, Egypt 1106kHz; Skopje, Yugoslavia 809kHz;
Tyne 1457kHz; Teeside (Stockton) 1594kHz. He also West Germany on 1421kHz and Radio Luxemburg
reports hearing La Coruna, Spain on 638kHz; AFN 1439kHz. Other more distant stations that have been
Bremerhaven 1142kHz and Radio Sud, Andorra on heard in the UK include Riyadh, Saudi Arabia on
818kHz. Andorra is a small independent state approx. 588kHz; Quazvin, Iran 841kHz (now with
situated in the Pyrenees between France and Spain. 2000kW); Rajkot, India on 1070kHz; Urumchi, China
Its other medium wave outlet is Radio Andorra on 1525kHz (usually in Russian with jamming) and the
701kHz and both stations will verify a correct recep- Voice of America Thailand 1580kHz in English at
tion report written in English, with a colourful QSL 2200hrs GMT. There is also the 1000kW outlet at
card. It appears that Andorra no longer broadcasts Calcutta, India on 1130kHz which has been heard
on the short waves and it is only on the medium by the writer during July at 2200hrs GMT with
waves that the DXers can hear broadcasts from this sign -on at the start of its Chinese programme. It is
mini -republic. Reception reports should be sent to worth looking for this station between the burble
Radio Andorra, B.P.I, 66720 Andorra -la- Vieille, on 1133kHz and Barcelona/Libya on 1124kHz.
VHF/FM DXing "burbling" note on continental stations, detected by
Mr. R. Ham in Sussex on 42 and 72MHz. These
by SIMON DAVID noises also interfered with television on channels 3, 4
FIRST of all, my thanks to all those readers who and 5.
wrote to me; I shall try to pick out interesting The target for most DXers is to see how far into
points from as many letters as my modest Europe one can penetrate on Band 2. Mr. G. P. Stan -
half -page allowance will permit and combine these bury tells a fascinating tale involving an Antiference
with any news items that are useful. 4element with two extra directors, a Rigonda
Many of you take Band 2 seriously as DXers and "Symphony" radiogram with home made tuning
this is really the basis on which this feature was meter in place of the magic eye, the f.e.t. preamplifier
started, but there are times when weather conditions, from April's P.W., and a rotatable aerial mounted on
particularly in the summer months, can produce some a cable controlled pulley system. In spite of some
odd twitterings even on the usual entertainment backlash, he has heard at his home in Chelmsford,
programmes from local stations. Essex, many BBC stations as far away as North
Mr. C. Rahn of Chesterfield has made a study of Hessary Tor and Wenvoe.
reception conditions and confirms that humid over- Continental pick-ups include five Dutch and three
cast atmospheres and very warm temperatures bring Belgian stations on Dutch network RTB-BRT, the
in some long distant signals. Of course, it is of little latter being Aalter on 90.4, 95.7, 98.6MHz and
help if conditions are cooler en route, so when you Veltem on 89.5 and 93.7MHz. West German stations
have one of those sultry sticky days and the weather- received include Langenberg and BFBS Cologne.
man says that this is spread over the whole country, There are local disturbances including a 400ft. hill
forget the lawn mower and switch on your f.m. and a police transmitter half a mile away thàt almost
receiver. swamps the continentals at times. There is, he says,
It does help to have a multi -element array and if a local river board authority transmitter which
you can arrange for it to be rotated easily, then you appears to be "ill-matched to its damp string!"
are in for a mixed bag of DXing. Mr. Rahn has four One of the problems of DXing in residential areas
aerials: a roof 'H' set to Sutton Coldfield; an indoor is the interfering reflections from neighbouring
'H' rotatable; a piece of unscreened wire about lft. aerials, and badly aligned tuners without i.f. traps on
long; and an indoor telescopic. The most fruitful, of the aerial can cause trouble. Mr. Stanbury appeals
course, is the rotatable which brings in most of the to all users to fit i.f. traps to keep the i.f. on a leash
BBC local radio stations from afar, plus numerous and I would endorse this wholeheartedly.
foreign stations. However, even Caen 95.6MHz was In the May article I mentioned rejection filters to
picked up by the telescopic. His tuner is the Omega suppress adjacent channels; the Wolsey Model No 2
ST -300C with a stereo decoder A1005M (G. W. Smith). covers 40 to 100MHz range with maximum rejection
Now with his new "weapon", a 6-element rotatable, of 45dB. Most good aerial dealers should have these
he is getting even better results. for around a fiver. Finally, the IBA have announced
There were disturbances on April 1st due to an on their medium wave test transmissions on 557kHz
aurora borealis. Although not visible due to overcast that v.h.f. tests start in the autumn on 95.8MHz
skies, the effects on v.h.f. broadcasting were a (entertainment), 97.3MHz (news).
257

www.americanradiohistory.com
 hearing the first hedgehog; Noddy's birthday.
In the April issue I asked the real G4GJ to "stand
up". Well, he has! Operational from Bingley in York-
shire since 1945 this station has a daily sked (not
weekends) with G3CJS on 3680kHz. These stations
have been doing some experiments with loop aerials.
Lionel Outridge (Canterbury) read my remarks re
4 metres (70MHz), and promptly built a converter
using dual -gate MOSFET's (r.f. and mixer) plus a
MPF102 crystal oscillator. Lionel says that a nearby
BBC relay on channel 5 puts out a string of 50Hz
modulated carriers right across the 70.1-70.3MHz
band which makes reception difficult. (Who do you
report the BBC to?). Other equipment is a FRDX400
and an indoor dipole. Stations received on 70MHz;
G3-AJS, FDW/P, FIJ, FZL, IIR, JEQ/P, LVK, LVP,
SHORT WAVES LVP/M, LVP/P, OHH, OQT, ORH, ORH/M RUA/P,
by DAVID GIBSON, G3JDG TDM/P, VER/P, VHH, VPK, VPS/P, WMR/P, YCN,
YTM, ZFP, ZRH, plus GB3SU, G4BLN, GW4ABR/P,
Agood month for the persistent listener and GW4BGG/P and G6SG. So the band isn't morgue.
some good DX loose on all bands -a
fair How about a few more of us breathing life into it?
Anyone hear 5GAA, HA25KFZ or O1KA? Gareth
assessment of the Amateur bands these past
few weeks. Eighty metres has yielded such little George (Cheltenham) did and asks what, whom, who
treasures as ZL2BT and DU1EJ, and even 7MHz has or where? (Perhaps someone else heard the first
seen fit to part with items like VK5CX and 5R8BD. hedgehog?). Receiver is an HRO with a 100ft. long
Good DX on twenty and fifteen but the surprise came wire. A twiddle on twenty brought: EAZGN, EA5FQ,
from 28MHz which has had spasmodic bursts of life. EA7QG, IT9JC, JA6BEE, JA6NPF, JA6YG, JA7BJA,
When this happened the DX was usually 599+ or JX1AK, JX5AZ, JY6UMS, OD5FB, VK30C, VK3BJB,
5 & 9+. Goodies on 28MHz logged include TU2DD, W7MTL/P, ZL2AAW, ZL2BFU, ZM2KG, ZK2BD all
VP2LI and ZM1HV. on s.s.b.
Occasionally one hears of an Amateur station Thirteen -year-old Chris Jones is alive and well and
accused of causing interference (QRM) to other living in West Bromwich. He also bagged: EA3WZ,
receiving equipment, usually television. If this hap- IT9FKS, JA3XKJ, W6CYU, all with a CX203 and
pens, the Amateur involved will take steps to solve 70ft. end fed on twenty metres s.s.b.
the problem and help effect a cure for such QRM. We stop this 14MHz revelry to bring you a news
The boot is now on the other foot. There seems to flash: a two metre log has been received. Guilty
be a marked increase in the number of intruders party is one David Noakes who resides at Cranbrook
into the Amateur bands. Not only this but worse; the in Kent. Using an f.e.t. converter (i.f. 28-30MHz),
interference caused by these illegal intruders is Trio JR310 and a 6-over -6 slot -fed he logged: F1AGY,
deliberate. Other Hams have reported this also. F.1CCP, F6CKU, G3AMF, G3FAB, G3RPZ, G3WKS/P
John Bagley (Birmingham) comments that we (Rutland), G3YOA, G8BXX/P, G8CIW, G8CLY/P,
should find out where the QRM is originating from G8FUF, G8FPR, G8GTD/P.
and then refuse to work Amateurs in that coun- Derrick Dance (Roxburghshire), CR70A, PR40
try(ies). It might, perhaps, be better to do exactly pre-elector, a.t.u. and 264ft. end fed sends in a nice
the reverse -make a point of working these localities log of stations heard on topband. On c.w.: DJ3CY,
and then diplomatically raising the question openly GI3YFY, GW3RTR, OHRSJ, OL1AOH, OL1AQL,
on the air i.e., "Do you suffer from QRM OM there OIJ5AQK, plus several GM, OM and OK2 stations. On
seems to be a strong source somewhere in your 160 metres s.s.b.: GM4BBL (Shetlands), GW3UCB,
area?". The RSGB has set up an Intruder Watch. GW3ZQN, W4BIF, OE5KE.
Perhaps its findings could be published? At the other end of the scale, Derrick reports these
A couple of hot tips have arrived. Listen 14250- on 28MHz c,w.: DLOIGI (beacon station), F3NB,
14300kHz at 123Ohrs. at weekends for YA1AH and ZC4CY (new beacon), 3B8MS (beacon), 3D6AX,
YAOCDR. There is a net on Friday mornings (14250 4X4SK, 9111CH. The s.s.b. signals on 28MHz came
-14300kHz) called the Arabian Nights (Knights) from: CREAM, CR6LF, CR7IZ, EA8GZ, EA8IB,
Net. Stations from VK and ZL frequently call in. LU8AJG, ZC4DS, ZE1AV, 4X4HF, 4X4NJ, 4Z4DZ,
Apparently that XG prefix heard by many mystified 4Z4LI, 9J2AY, 9J2TB and PY5UI on a.m.
souls earlier this year was used by XE1J. Something Events during June include: June 9-10, four metre
to do with a 450th anniversary. Another callsign was open contest; 10, d.f. qualifying round at High
changed because of the seventh Games held in Wycombe; 16-17, Microwave Field Day; 17, WAB
Panama City. When will G stations get in on this call- v.h.f. contest (phone); 23-24, First Topband contest;
sign changing act? There are many events in 24, d.f. qualifying round at Chelmsford. July 7-8,
England which merit an instant change of callsign: Jubilee v.h.f./u.h.f. contest.

BROADCAST BANDS AMATEUR BANDS

Short Wave Reports by 15th of the month to Malcolm Connah, 59 Windrush, Short WavefVHF
Highworth, Swindon, Wiltshire, SN6 7DT. Logs in alphabetical order please
Medium Waves Logs to Charles Molloy, 132 Segars Lane, Southport, PR83JG. by 15th of the month to David
VHF/FM Reports to Simon David, c/o Practical Wireless, Fleetway House, Gibson, G3JDG, 12 Cross Way,
Farringdon Street, London, EC4A 4AD. Harpenden, Hertfordshire.

258

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259

www.americanradiohistory.com
TAKE 2
DAVID ANDREWS
No. 50
ELECTRONIC SIREN
Veroboard strips
+9v

A series of simple transistor projects,

using not more than twenty components.
THIS month's project describes a siren that
utilises a voltage controlled relaxation
oscillator. The output of the oscillator is fed
to a very simple loudspeaker driver stage comprising
Tr3 and Tr4 connected as a super -alpha pair.
Alternative output stages to provide higher power o

can be used provided they present a comparatively o 0

high input impedance.
o o
SWt
Circuit . o o 0 0

Trl and Tr2 form the active part of the oscillator. 0 o o 0 0 0 a

They can be almost any type of general purpose

S.
o o 0 o o

E
0 I
pnp and npn transistor respectively; but make sure
they are connected the right way round. The fre-

Suggested layout of components on a piece of veroboard.

quency of oscillation is set by the values of R1 and Cl

together with the potential at the base of Trl. In
this instance the potential is determined by the
network of R2, R3, R4 and R5 and is dependent on
whether switch SW1 is open or closed. C2 serves to
delay the build up and fall of this potential and
gives a smooth change of frequency that gives rise
C3 to the siren "wail".
50yF Assuming that SW1 is open and that the potential
at Trl's base is low, Cl will charge up through Rl
L.S.
3511
until the base/emitter junction of Trl is forward
biased. Not much charge is needed on Cl to arrive
ov at this situation and it occurs very early on in the
charging cycle. When Trl is turned on regenerative
circuit of the electronic siren.
feedback occurs between Trl and Tr2 and the charge
The complete
of Cl is shunted to negative through the circuit of
Trl's emitter and collector and Tr2's base and
* components list emitter; at the same time the collector of Tr2 is
pulled down towards negative. Eventually base
current into Trl ceases to flow and Cl is free to
R1 100k5ì 1p re -charge through R1 to repeat the cycle; the poten-
1p
R2 1k5ì tial at Trl's base returns to its original state. If this
R3 5.6k12 1p
R4 1.2k52 1p
potential was higher it would take more time for Cl
R5 12kí2 1p to reach a charge whereby the emitter of Trl became
R6 15052 1 p more positive than the base and thus the frequency
Cl 0.01pF 4p of oscillation is reduced. By closing SW1 we force
C2 501.LF 10p the potential to increase but this does not happen
C3 50/LF 10p immediately and the rise is slowed up by the time
Tri 2N3702 20p constant given by C2. The frequency of oscillation
Tr2 BC108 10p reduces slowly to a minimum value set by the
Tr3 BC108 10p
potential divider effect of R4 with R5. When the
Tr4 BC108 10p
SW1 Pushbutton switch 15p switch is opened the potential reduces slowly as the
charge on C2 is bled to negative by the momentary
95p spikes of current drawn by Tr2 through R2. While
this happens the frequency of oscillation slowly
No allowance is made for minimum order costs or increases.
for postage and packing and these points should be
checked carefully before ordering.
-continued on page 261
260

www.americanradiohistory.com
 My complaints have also been for drawing our attention to these
supported by the Horsham -based signals.
1et ót, Southern Independent Radio
Association, and the Brighton-
We did not find any trace of a
transmission of Radio 1 on Long
based Southern Free Radio
. Waves, or of Radio Brighton on
Campaign, both of which are 530 or 560 metres. But it may be
responsible organisations, who worth pointing out that with a
are trying to improve the stan- receiver i.f. of 'around 465kHz,
dards of broadcasting in this the `image' appears at approxi-
country. mately the frequencies mentioned,
Regarding the possibilities of because
covering the whole country on
medium wave with a few kilo-
-
1484 (2 X 465) = 554kHz
(i.e. 542 metres)
watts, the BBC should try using 1214-(2x465)=284kHz
horizontal long-wire aerials (Le. 1058 metres).
Shoreham Transmitters instead of vertical masts. Using Such `signals' are of course
this method, the Independent entirely the product of the super -
I was interested to read Mr. Broadcasting Authority's test
Woodward's letter in your March het receiver, and do not exist as
broadcasts on 539 metres medium transmissions at all.
issue. He complains that our wave cover large parts of the
transmitters at Shoreham "cause There is no point in going into
country, with a power of one kilo- great detail about the problems
countless harmonics all the way watt, despite the fact that a
down the medium wave band". of medium -wave transmitting
powerful Dutch pirate station is aerial design here, which are
The frequencies used at Shoreham on 538 metres, directly under-
are 692kHz (Radio 4), 1214kHz many and complex. I am afraid
neath. that the horizontal long-wire
(Radio 1), and 1484kHz (Radio The IBA's transmitter is also
Brighton). aerial which Mr. Woodward sug-
audible in parts of Holland, over gests is not suitable for serving
It is true that after the exten- the aforementioned Dutch station. very large areas by day and by
sive wavelength changes last 1 also know for a fact that many
September a number of inter - night.
on -shore pirate radio stations, The IBA test transmissions are
modulation products were identi- notably Radio Jackie of London not made from such an aerial,
fied but the situation was quickly and Focus 240 of Worthing cover
rectified. G. H. Sturge (BBC and their relatively large cover-
distances of as much as 30 miles, age is due mainly to the high
Engineering Information Dept). with the 'massive" transmitter earth-conductivity of the area
power of 7 watts! They also use adjacent to the River Thames.
Noises efficient, long-wire aerials. P. Nevertheless the station does not
... The fact remains that several Woodward (Lancing, Sussex). serve large areas of the country
miles from the transmitters, nor is it intended to do so.
noises identifiable as Radio 1 can We understand that recordings
be heard loud and clear on Corrective Action made in Holland reveal the IBA
266 metres, 232 metres, and also . . . Following Mr. Woodward's signal as only just detectable in
on 1100 metres long wave on further letter, we have carried out the presence of the pirate. It
receivers ranging from small some further checks and measure- should also be remembered that
transistor radios to powerful com- ments in the Brighton area. We there is a limit to the degree to
munications receivers. The found two spurious signals spaced which the service area of a
strength of these signals varies about 80kHz above and below the station can be enlarged by
from day to day, and on some frequency of Radio 1 (1214kHz). increasing the power or using a
occasions I have heard Radio 1 These signals were intermittent different type of aerial, and the
very weak on 247 metres, and and of comparatively recent power necessary to serve a given
very strong on 323 metres. origin, and they were only present area depends on very many
In addition, Radio Brighton is when a certain combination of factors, not the least of which is
always clearly audible on approxi- enuipment was in use at Shore- the level of interfering signals
mately 530 and 560 metres ham. The necessary corrective which must be overridden. G. H.
medium wave, as well as the action has now been taken, and Sturge (BBC Engineering Infor-
intentional 202 metre wavelength. we are grateful to Mr. Woodward mation Dept).

TAKE 20-Electronic Siren as it affects the working points of the two transistors.
-continued from page 260 The output is taken from the junction of Rl with
Cl and this is a very high impedance point and
Operation if too much current is drawn by an external circuit
On initial switch-on it is possible to get no Cl may never reach a charge at which regenerative
immediate high frequency oscillation and this prob- triggering can occur. Hence the need for a reasonably
lem can be overcome by temporarily shorting out R3 high input impedance to the amplifier stage. The
and when the audible tone is heard the shorting output waveform is a sawtooth and its amplitude
link can be removed. Varying the potential divider decreases as the frequency increases which is quite
effect of R4 and R5 will set the minimum lowest effective in compensating for poor low frequency
frequency. The highest frequency, before complete response of small loudspeakers.
cut off, is best set by Cl. R1 could be adjusted to The estimated cost to build this project is 95p,
vary the range of frequency but this is undesirable plus cost of the speaker, Veroboard, and VAT.
261

www.americanradiohistory.com
 ON RECENT DEVELOPMENTS

contact o her deaf -blind people by Office Research Station, Dollis Hill,
COMPUTERS are s eadily becoming
increasingly invo ved in our lives. using the machines in conjunction London. Mr. Harrison is Chairman
Latest event to highlight this was the with the to ephone. But wait; how will of the Southern Region Industrial
official opening of America's first they hear the telephone ring? In Savings Committee; Racal are not
computer-controlled petrol station practice they don't have to because directly connected with ERNIE.
which also boasts on-line credit the inventors have thought of this
checks. The motorist can pay cash or problem. Their answer is a tiny unit
offer a credit card; the mini -computer which is carried on the person-
will accept either. However, just like rather like a radio paging bleeper.
Instead of emitting a warning bleep FLAT -SCREEN TV
its human counterpart, man, the com- Last month I reported thin readout
puter is happy to accept cash but when the telephone rings, the unit
simply vibrates. What a wonderful devices and suggested flat screen
wary of the credit card. When such a
application of electronics this is. television. I have just come across a
card is offered the computer will flat -screen cathode ray tube (c.r.t.) or,
immediately check and verify it with the to be more precise, two inches deep.
central computer files held in Atlanta. Its function (at present) is to display
The petrol station is in the suburbs of alpha numeric characters/messages
Los Angeles. If the credit card offered THE "R.O.M." and it does not use either electron
to the computer is out of date, or has Big international exhibitions are guns or deflection plates. It is digitally
been stolen, then the computer will heavy going but often there are one or
addressed and the display forms 512
simply "pocket" the card and will two very interesting items which crop
characters in a 5 x 7 matrix of dots.
refuse to return it. Now there's some- up. At this year's Mesucora exhibition
The screen measures 5.4 x 3.8 inches.
thing you'd scarcely credit. in Paris, one company exhibited a
It has an area cathode which emits a
digital multimeter which incorporated
a digital thermometer. Thus, in addi-
sort of blanket of electrons as opposed
to the narrow beam normally associa-
ONE STEP AHEAD tion to the usual multimeter capability
ted with the more conventional (and
A quick note to exponents of ESP of measuring voltage, current and
very much longer) c.r.t.
(extra sensory perception). There resistance, it offered the measurement
Beam forming is achieved by a plate
is to be an International conference of temperature also.
with some 20,000 holes in it. This
Unfortunately, as temperature rises,
on "Electrical Signals fromtheBrain". "forms" the electron blanket into
.

the transducer or sensor gives an

It is to be held at Oxford University, output which does not follow a linear individual beams. These beams then
August 28-30, 1973. Anyone got have to pass through four plates each
law and therefore cannot "change"
any brain waves? degrees C directly into digital reading. similar to the beam forming one. These
The solution used was to employ a plates are the switching mechanism
by which characters are formed. The
ROM (read-only memory). This mem-
DEAF -BLIND HELP ory can be programmed to take certain
first two plates (of the four) determine
In Hanover, there is a Centre for correcting actions. For example; if the position of the characters on the
deaf -blind people. How do such un- the sensor was measuring 500°C and screen while the remaining two
fortunate humans communicate? Feel this, when fed directly to the digital determine the column and row.
or touch is an obvious answer. They display gave a reading of, say, 537, A 75V positive potential will acceler-
can, for example, read Braille by feel- then the ROM could be programmed to ate electrons through the holes in the
ing the raised dot impressions which compensate for this. Whenever a switching plates, while a 50V negative
make up the Braille alphabet. They 500°C signal came in, the ROM would
potential will cut off the beam com-
cannot, of course, either see or hear alter things by subtracting 37 from pletely.
television nor can they hear or answer the answer before it was displayed. After travelling through the switch-
a telephone call. Again, perhaps 600°C might read ing plates the electron beam(s) now
An ingenious system has been in- (fed direct) 671 and thus the ROM's pass through a final plate used for
stalled at the Hanover Centre which programme would tell it, "If 600 in, focusing. They then strike the
enables deaf -blind people to com- subtract 71 to give 600 display". Thus phosphor screen thus creating an
municate directly with each other, the whole programme takes account illuminated image. The very small
over great distances-theoretically, of any input and processes it so that thickness of this unique c.r.t. (2in.)
anywhere in the world. Key to this the "correct" temperature reading is has numerous obvious advantages.
system is the Braillomat. This machine shown digitally. Other advantages are also present
produces a strip of paper with Braille which may not, at first sight, seem
alphabet letters or dot characters quite so obvious. Because the electron
raised on it. Thus the deaf -blind beam has such a very short distance
person has only to run the strip of to travel, the display is virtually
paper through his/her fingers to INTEREST IN "ERNIE" immune to magnetic interference.
"read" the message. The Braillomat In the May article, the story about Note: This display, although it has
has a keyboard rather like a type- "ERNIE" might have implied that the been exhibited and is not an industrial
writer, but it is extremely simple in name was derived from Ernie Harri- secret, is not yet on the market al-
that it has only six keys-one key for son and possibly that Racal Elec- though its appearance is believed to
each of the dots in the Braille alphabet tronics were connected with the be imminent.
pattern. The idea is that by connecting Premium Bond selection equipment.
two of these machines together, two We would like to record that the
deaf -blind persons can "chat" happily.
The tape output, incidentally, is rather electronic equipment was developed
like teletype or teleprinter tape. by Plessey and that ERNIE is derived
It doesn't take too much imagination from Electronic Random Number
to see the potential here. Each deaf - Indicating Equipment, the original
blind person with a Braillomat could version being developed at the Post

262

www.americanradiohistory.com
 WEYRAD
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263

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 P. C. BOARDS
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spacing compatible with published front panel £1 '20

The Space Age WORLD RECORD award winning 7' 6" long
All Band JOYSTICK VFA Antenna -JOYMATCH A.T.U.
TRIO RECEIVER or TRANSCEIVER-Matching HEAD-
- 8
SET or R's, C's, SIC's, Slider Pots, Transformer £6.80
WATT AMPLIFIER (Nov
PCB (Mono-24in x 3in) 60p
1972)

PHONES -A
COMPLETE STATION IN ONE COMPACT
R's, C's, Semiconductors: Stereo Set £7.70, Mono Set £3.90
PRE-AMPLIFIER (Nov 1972)
PACKAGE-THE FLAT DWELLER'S DREAM ! PCB (Stereo-3}in x 71in) Specially designed to also hold all Pots.
either rotary or slider, plus Selector Switch £I SO
R's, C's, Rotary Pots, Selector Switch, Semiconductors:
Stereo Set £5.20, Mono Set £2.50
JOYSTICK VFA £1254 (A); JOYMATCH ATU 111
LOUDHAILER & SIREN (Dec 1972)-PRE-AMP & SIREN
*or 111A £1254 (B); JOYMATCH ATU LO -Z500 £18.10 GENERATOR
(C) Set of R's, C's, Pot, Semiconductors PCB (2}in x 2}in) £2.20
VIBRASONIC GUITAR PRE-AMP (Sept 1970)
PCB (4in x I Sin) for Mic Pre -Amp, 2 -Guitar Pre -amp, Tremulant
& Tone Controls, Master Volume. Specially designed to also hold
COMMUNICATIONS HEADPHONES £2.86 (D) Rotary or Slider Pots £2.30
Set of Slc's, R's, C's, Rotary Pots, LDR, Lamp, Coupling T/former
£7.75 Power Supply £2-S0
(All Including V.A.T., carriage, packing, accessories & DIGITRONIC DIGITAL CLOCK (Mar 1973)
insurance.) 6 -digit read-out 60p
PCB (I din x 3}in) for
POSTAGE: U.K. IOp any order. OVERSEAS at cost.
PARTRIDGE PACKAGE No. 1 PARTRIDGE PACKAGE No. 2 P.E. DESIGNS ALSO AVAILABLE-S.A.E. FOR FREE LIST.
8R59DS receiver .. £5445 JR310 receiver .. .. .. £82 50 V.A.T.: ADD 10°%s TO ALL U.K. ORDERS
Items (A); (B); (D) above .. E12 10 Items (A); (B); (D) above .. £7.70
Complete Gen. Coverage
Station .. .. .. £68.55 Complete Amateur RX Station E00 20
PHONOSONICS
DEPT. PW7, 25 KENTISH ROAD, BELVEDERE, KENT, DA I7 5BW
PARTRIDGE PACKAGE No. 3 PARTRIDGE PACKAGE No. 4
MAIL ORDER ONLY
JR598 receiver .. .. £20350 TS/PS515 Transceiver 180W £23100
Items (A); (B); (D) above .. FREE Items (A); (C); (D) above .. FREE

Complete Amateur RX Station £203.50 Complete TX-RX Station .. £231.00

BARCLAYCARD - ACCESS !
FERRANTI Radio Lc.
ALSO: SP5D SPKR. £4.95; OA2 MAINS STABILISER 74p.
41 4i only Li -32
WITH FREE DATA
NEW : World-wide reception on the amazing 1í1'859 15D ZTX300 12p ZTX502 17p 28178 38p
"DX-CRYSTAL SET" £2.20 including unique 81'880
ßF881
20p
20p
ZTX301
ZTX302
19p
17p
ZTX503
ZTX504
14p
48p
Z8270
Z8271
110
lap
aerial. 8F898
81/897
16p
28p
ZTX303
2TX304
)4p
21p
ZTX530
28142
Elp
33p
Z8272
Z8274
l8p
lop
ßF898 20p 2TX310 9p 28170 10p 28278 26p
ZTX107 89 ZTX330 15p 28171 18p Z8278 870

PARTRIDGE BUDGET LINE ZTX108

ZTX109
ZTX214
Bp
lip
169
ZTX384
ZTX500
ZTXOO1
1ßp
12p
lap
28172
28174
Z8178
113p
17p
2Sp
Zesers
KSO30A to
K9180A 19p

ARTIFICIAL EARTH-SOLVES YOUR EARTH PROB- All devices top grade, brand new, fully guaranteed. We specialize in
Ferranti semiconductors and can supply any device. Postage & Packing 10p.
LEMS £5 28; AERIAL BANDSWITCH-TUNED AERIAL Free over £2. Send S.A.E. for full list and data. All prices Include V.A.T.
£5.28; A.T.U. KIT-FULL COVERAGE TX/RECEIVER DAVIAN ELECTRONICS
£5 28; ASSEMBLED £6 38. PO BOX 38 OLDHAM , , LANCS. OL2 6XJ
NEW: Instrument Cases, easily drilled in strong black
rigid polystyrene. 516" x 3 6" x 2" only 20p.

(All including, V.A.T., carriage, packing, accessories &

Newest, neatest
system ever de- -N T
E -R -L-O -C -K-I -N -G
insurance.) Send 3p stamp for full illustrated details of
Partridge Products. TIO brochures (state which) 3p stamp
extra.
vised for storing
small parts and
components : re-
sistors, capacitors,
diodes, transis- M
PLASTIC STORAGE DRAWERS
-' /%%//II
r1 e
tors, etc. Rigid
plastic units, in- nor!
NO V.A.T. ON OVERSEAS ORDERS! terlock together
in vertical and
horizontal com- DISCOUNT
-11111AI
Trans--
binations. Trans
CARRIAGE & INSURANCE EXTRA OVERSEAS. pare. plastic
drawers have label
slots f removable
IRIcE5 10

space dividers. Build up

any size cabinet for wall, bench or able top.
BOX 5 SINGLE UNITS (5-x2}x2}) £1.25 Dozen
DOUBLE UNITS £2.15 Dozen 5 SIZES
TREBLE (3D) £2.20 for 8 ALL MISER
DO UBLE TREBLE 2 drawers in one outer case (6D2) £3.25 '
PARTRIDGE ELECTRONICS LTD. for 8 extra large size (6DI) £3.1 Ofor 8, Carriage 35p
QUANTITY DISCOUNTS! 5% in LI for orders over £6, 7+ over
Orders over £10 post free
LIP, 10% over £20. Quotation for large quantities.
PLEASE ADD 10% VAT TO TOTAL REMITTANCE.
BROADSTAIRS, KENT (Dept. PW7), 124 CR!CKLEWOOD BROADWAY,
Phone : 0843 62535 or 62839 cheap periods. /YORYET
Lt M rT6
LONDON N.W.2 01-4504844

264
TIACCILCUIQ
Mood Lighting System
PART FOUR JUREK BUDEK*

-continued from the June issue Assembly

As the load increases, the suppression of radio Pay attention to the correct polarity of capacitors,
frequency interference becomes more difficult. Many diodes, transistors and triacs. Mount the pulse
sophisticated and very effective circuits have been transformer in correct way, i.e. to avoid sideway
published and are on the market, but very often fixing.
they are prohibitive to the normal user because of The three core mains lead enters at the rear of the
their high cost. chassis (Fig. 20, page 54, May issue) and is con-
The suppression filter used in this article is very nected to the junction terminal block.
simple, inexpensive and quite effective. It is suitable Thereafter, the connections to the junction ter-
for total loads up to 900 watts, and consists of one minal block are as indicated in the printed circuit
bifilar wound ferrite core filter choke and 0.1µF board wiring layout diagrams in this issue. It is
capacitor as shown in Fig. 23. pointed out that the mains `earth' lead (E terminal)
should preferably be taken directly to the control
unit chassis. In Fig. 20 (May issue) this was shown
soldered to the `earth' side of the printed circuit
board layout.
Load When the printed circuit board is mounted in the
chassis metalwork, the `earthy' side of the foil is
240V
50Hz
0.1NF Troc connected to the metalwork via the mounting spacers,
CH1
thus ensuring continuity of the chassis-p.c. foil earth
system.
Therefore, the mains earth lead (common) and
the earth lead from tag 1 on the lamps output socket
SKI may be conveniently taken to a chassis earth
Fig. 23: The suppression circuit used in the mains input supply to the
lamp dimming control unit. tag which may be mounted under one of the metal
bolts that hold socket SK1 in position.
The socket SKI is wired otherwise as shown in
The normal symmetrical currents generate mag- Fig. 20.
netic fields which are self cancelling. However, The three triacs, CSR3, CSR4 and CSR5, are in all
symmetrical currents, caused by radio frequency instances bolted directly to the common heat sink
interference are attenuated.
Mains Lead
Lamps power socket

0000co
F53 F52
o o odo Fig. 24: Rear view of the P.W.
Tricolour. The DIN plug and
socket are the audio signal feed
points-to amplifier output and
CD loudspeaker.

FS1 4
Audid output

142M;Plua
Texas Instruments Ltd.
265

www.americanradiohistory.com
 Ir,

i: ;¡ ¡: :¡
L._.1. L-1=
II
I I
- r=I
;

11-L1
I I
j j

I I Ì j
L -J L -J

266

www.americanradiohistory.com
Build yourself a TRANSISTOR RADIO
ROAMER 10 WITH VHF INCLUDING AIRCRAFT
10 TRANSISTORS. 9 TUNABLE WAVEBANDS, MW1,
MW2, LW, SW1, SW2, SW3, TRAWLER BAND. VHF Total building cost
AND LOCAL STATIONS ALSO AIRCRAFT BAND
Built in Ferrite Rod Aerial for MW/LW. Retractable, chrome plated 7 section Telescopic
Aerial, can be angled and rotated for peak short wave and VHF listening. Push Pull output
using 600mw Transistors. Car Aerial and Tape Record Sockets. 10 Transistors plus 3
Diodes. Fine tone moving coil speaker. Ganged Tuning Condenser with VHF section. P. P. & Ins. 52p
Separate coil for Aircraft Band. Volume on/of. Wave Change and tone Control. Attractive
Case In black with silver blocking. Size 9" x 7" x 4". Easy to follow instructions and Overseas P. & P. 51.051
diagrams. Parts price list and easy build plans 30p (FREE with parts).

ROAMER ROAMER
ROAMER SIX
EIGHT
SEVEN 6 Tunable Wave-
MkI bands: MW, LW,
SW1, 81V2, 8W3
Trawler, band plue
MK IV an extra Medina.
waveband
NOW WITH easier t u n i n g
for

VARIABLE of Luxembourg
7 Tunable Wave- etc. Sensitive fer-
TONE CONTROL band.: MW1, MW2, rite rod aerial and
LW, 8W1, SW2, telescopic aerial
7 Tunable Wavebands: MW1, MW2, LW, SW1, SW2, BW3 and Trawler for Short Waves.
SW3 and Trawler Band. Bull in Ferrite Rod Aerial Band. Extra Medium waveband provide, easier tuning 31n. Speaker. 8
for MW and LW. Retractable chrome plated Tele- of Radio Luxembourg, etc. Built in ferrite rod aerial stages -6 translators and 2 °lodes. Attractive black
scopic aerial for Short Waves. Push pull output using for MW and LW. Retractable 4 eectlon 24ín. chrome case with red grille, dial and black knobs with pollehed
600mW transistors. Car aerial and Tape record socket.. plated telescopic aerial for SW. Socket for Car Aerial. metal Inserts. Size 9 X 51 x 241n. approx. Easy build
Selectivity switch. 8 transistors plus 3 diodes. Fine tone Powerful push-pull output. 7 translator, and 2 diode., plans and parte price list 200 (FREE with parts).
fins tone moving coil speaker. Air spaced ganged
moving coil speaker. Air spaced ganged tuning con- Total building costs
denser. Volume/on/off, tuning, wave change and tone
controls. Attractive case in rich chestnut shade with
gold blocking. Size 9 x 7 x 41n. approx. Easy to
tuning condenser. Volume/on/off, tuning and wave
change control.. Attractive case with carrying handle
Size 9 x 7 x 4in. approx. Easy to follow instructions
(Overseas P. a P. £1.03) £4.38 Ins. iss 31p

follow instructions and diagrams. Parts Price List ano diagrams. Parta price list and easy build plane
and Easy Build Plans 25p (FREE with parts). 26p (FREE with parts).

Total building cost 7.68v p.In P,47p.a Total building costs .Ls6.
(Overseas P. a P. 81.05) sari
t8 p p s
iJv Ins. 47p.
e

(Overseas P. k P. 51.05) oTr s.

e TRANS
TRANSONA EIGHT
POCKET FIVE k" 8 TRANSISTORS
and
FIVE I 3 DIODES

5 TRANSISTORS
6 Tunable Wave-
3 Tunable Wavebands:
MW, LW, Trawler Band
- ___ bands: MW, LW,
8W1, 8W2, SW3
AND 2 DIODES d Trawler Band.
with extended M.W. Sensitive ferrite rod aerial for M.W. and L.W. Tels.
band for easier tuning 'iconic aerial for Short Waves. 31n. Speaker. 8 Improved
of Luxembourg, etc. 3 Tunable Wavebands: MW, LW and Trawler Band. type transistors plus 3 diodes. Attractive cue In
7 stages -5 transistors and 2 diodes, 7 stage -5 transistor. and 2 diodes, ferrite rod aerial. black with red grille, dial and black knobs with polished
supersensitive ferrite rod aerial, One tuning condenser volume control, One tone metal inserts. Size 9 x If x Min. approx. Push pull
tone moving coil speaker. Attractive black and gold moving coil speaker. Attractive case with red speaker output. Battery economiser switch for extended battery
case. Size 51 x 11 x 3fln. Easy build plans and grille. Size 6f x 44 x 1}in. Easy build plans and life. Ample power to drive a larger speaker. Parts
parts price list 10p (FREE with parte). parts price list NOD (FREE with parts). price list and easy build plane 26p (FREE with part.).
Total building costs Total building costs rff7G p p Total building costs
(Overseas P. & P. 65p) aiL 11/ In.. 25p
&
(Oversee P. A P. 81.05) £4.95 Ins. P. P.33p
a

NEW! "EDU-KIT 77
BUILD
RADIO EXCHANGE CO
RADIOS, AMPLIFIERS, ETC.,
FROM EASY STAGE DIAGRAMS. FIVE
UNITS INCLUDING MASTER UNIT TO 61a HIGH ST., BEDFORD, MK40 1SA. Tel. 0234 52367
CONSTRUCT. Reg. no. 788372
COMPONENTS INCLUDE:
Tuning Condenser: 2 Vohme Controls: 2 Slider I enclose £ please send items marked.
Switches: Fine Tone Moving Coll Speaker: Terminal
Strip: Ferrite Rod Aerie.: 2 Plugs and Sockets: ROAMER TEN ROAMER SEVEN D
Battery Clips: 4 Tag Boards: Balanced Armature
Unit: 10 Traneietora: 4 Diodes: Resistors:
Capacitors: Thee 4" Knobs. Units once ROAMER EIGHT TRANS EIGHT D
constructed art detachable from Master
Unit, enabling them to be stored for TRANSONA FIVE D ROAMER SIX D
future use. Ides] for Schools, Educational
Authorities an4 all those interested In
radio construct on.
POCKET FIVE D EDU-KIT D
Parts price list and easy build plane 255
(FREE with parts). Parts price list and plans for

(Overseas P. a P. fl US
All parts including
Case and Plans
18.8i!
erV 5 i' p g
Ins. 33p Name

FULL AFTER ' Callers side entrance "Lavells" Shoe Address

SALES
rJ
e Open 10-1, 2.30-4.30 Mon. -Fri. 9-42 Sat.
PW54
WalauWWWIlalaula
SERVICE PLEASE NOTE: ALL PRICES NOW INCLUDE VAT

267

www.americanradiohistory.com
 All price, in pounds and new pence
6ßA6 25 676 20 7C5 11.18 128R7 40 37 40 DAF91 30 EBL31 81.50 EL34 60 878 5150 P1.500 80 U403 60
8ßE6 80 6J7M 45 7C6 75 14117 50 42 60 DAF98 45 EC90 88 EL41 80 N108 11.50 PL504 80 U404 CO
VALVES 613118 75 6.170 30 705 60 19AQ6 50 50135 50 DCC90 21.36 ECC81 85 EL42 66 0A2 88 PL508 90 U801 5118
BBJB 60 6J7GT 46 7117 60 20D1 50 5005 60 DF33 65 ECC82 80 E1.84 25 003 38 PL509 11.80 UABC80 40
1A7GT 45 6BQ7A 50CD8G11.20 DF70 45 ECC83 30 21,95 85 0Z4 40 P1.802 95 UAF42 65
105 46 6K6GT 60 7127 75 20F2 70
60 613127 90 6K7M 86 787 12.25 20L1 81.10 50L6GT 55 DF91 ECC84 30 ELL80 61.00 PC86 80 PX4 12.50 UBC41 50
1116 40 EM80 45 PC88 PX25 22.60 UBCe1 40
IN6GT 50 6BR8 70 6K7G 35 7Y4 65 20P4 51.10 75 60 DF92 20 ECC85 60
55 6B67 11.80 6K7GT 35 9ßW6 80 20P5 11.20 78 46 DF98 46 ECC88 40 EM81 80 PC97 50 PY33 88 UBF80 40
IRS 25A8 65 DH77 35 ECH2I 68 EM84 85 PCC84 40 PY81 80 UBF89 36
184 40 6BW6 85 6K8M 80 10C2 68 86 80
80 8BW7 80 OKBG 40 10F1 25L6GT
75 50 85A2 50 DK32 45 ECH35 11.00 EY61 40 PCC89 60 PY82 35 UCC84 48
I85 15022 80 DK91 40 ECH42 76 EY86 40 PCC189 56 PY83 38 UCC85 40
IT4 80 6C4 88 6K8GT 60 10F3 25Y6
90 86
30 OCIO 85 6K2S 75 10F9 25Z4
60 80 150C4 60 D1192 65 ECH81 80 EZ36 40 PCF80 30 PY500 11.00 UCF80 65
3A4 25Z5GT 6060 DK98 60 F.CH83 45 EZ40 50 PCF82 36 PY800 40 UC1142 70
3Q4 40 6C6 26 6L60 60 10E18 50 55 801
50 6CD60 11.25 81.18 46 1OLD11 2IZ6
85 85 807 DL68 11.26 ECL80 45 EZ41 60 PCF84 80 PY801 50 L'CH81 40
3Q6 813UOA1375 DL92 85 ECL82 35 EZ80 27 PCF88 60 R2 75 UCL82 35
384 60 OCHO 60 BQ70 40 10P13 60 30C1 80
35 6CW4 65 6Q7GT 48 11E3 14.00 30C16 80 866A 75 01.93 40 ECL83 70 EZ81 29 PCF801 50 R19 50 UCL83 60
394 12AT6 30C17 954 60 DL94 48 ECL88 40 GY501 80 PCF802 50 8130 11.75 UF41 60
48 606 35 68A7M 40 80 90
IR40Y 75 6E5 21.00 B8C7M 75 12AT7 85 30C18 80 1625 65 DL9S 50 ECLL800 0Z30 40 PCF806 80 SP4 60 UF89 40
152740 85 6F1 70 8807M 40 12AU6 85 30F6 86 4022AB1650 DL90 46 82.26 GZ32 48 PCF808 70 BP41 £8.00 UL41 65
5V40 45 SF50 90 68H7M 40 12AU7 80 30FL1 76 5763 70 DM70 45 EF9 75 G7.34 60 PCF808 85 8P81 75 UL84 40
6Y3GT 40 SF00 86 68J7GT 80 12AX7 80 30FL12 11.20 7193 80 DY88 38 EF37A 11.20 HN309 21.60 PCL82 86 8TV280/80 UM80 80
5246 40 6F80 60 88K7GT 40 12BA8 40 30FL14 85 7475 60 DY87 88 EF39 60 KT38 51.00 PCL83 65 110.00 UU9 50
6/30L2 80 ßF11 40 68L7GT 85 12ßE6 40 301.16 85 A61 48 E8800 06 EF41 86 KT61 11.76 PCL84 46 8U25 2100 UY21 50
6A7 75 6F13 45 68N7GT 85 12C80T 36 30L17 80 ATP4 45 EA50 20 EF60 25 KT66 12.05 PCL85 40 8U2150 70 UY41 48
6,480 40 88Q7GT 40 12E1 18.00 30P4 81.18 ATP6 80 EABC80 55 EF52 81.26 KT81 11.76 PCL86 46 T41 11.00 UY85 40
BU4GT 46 12J5GT 80 30P12 80 ATP7 80 EAF42 55 EF80 25 KT81(7C5) P0500 01.80 TDD4 80 VMP4G 85
6AK6 85 ßF23 85
6U5G 2100 12J7GT 60 30P19 86 AU2 8440 EB91 90 EF86 86 51.18 PENA4 11.00 1110 75 VP4B 11.26
ßF24 76
6AM6 85 6F26 11.00 BVBM 60 12K7GT 40 30PL1 75 AUS 7b EBC33 60 EF88 80 KT88 52.26 P155.134 5140 U14 76 VR105/30 88
6AM6 88 ßF28 05 !WOG 30 12K80T 60 30PL13 98 AZ1 55 EBC41 55 EF89 28 KTW6181.76 PEN46 75 1719 18.00 VR150/30 86
6.4616 38 6F32 25 BVBGT 40 12Q7GT 40 30PL14 90 AZ31 65 EBC90 86 EF91 38 KTZ41 60 PEN48 40 U25 80 VU111 75
88870 85 608 86 8X4 8b 12BA70T 60 35A6 75 CBL31 11.00 EBF80 40 EF92 36 mu 88 PL36 56 U26 80 VU120 11.00
351.6 60 00836 7b EBF83 EF98 75 MLB 40 PL81 60 U78 36 VU608 18.00
OATS 85 606 28 6X56 40 12807 36
35W4 56 CL33 5180 EBF89 40
EF181 70
SACO 25 675M 60 8X5GT 40 12887 86 36Z3 CY30 08 80 EF184 M MSP4 50 PL82 45 U191 76 W81M 88
70
6840 01.00 6750 20 7138 70 12877 40 35Z40T 60 CY31 48 EOM 2100 EL32 60 MU14 75 PL83 46 U251 80 Y63 11.8
61380 25 6J50T 30 787 60 128K7 60 3526 50 DAC32 50 EBL21 60 EL33 21.76 MX40 88 PL84 40 U301 68 7.7590N £84
AC128 20 BY100 15 NKT713 16 0C44 17 7430 20 7474 40 74100 12-50 74157 1180
Transistors ACY20 20 BZY88 15 0A70 10 0C46 12 Integrated 7432 42 7475 66
45
74107 60 74170 1410
ACY39 60 CR81.40 47 0A71 10 0057 80 7433 70 7478 74110 80 74174 12-00
118914 07 2182219 20 ADI40 60 DD003 15 OAK 08 0058 60 Circuits 7437 65 7480 80 74111 21.45 74175 11.36
10113 25 282369A 16 AD149 60 GET102 80 0A85 12 0059 46 7438 66 7482 87 74118 21.00 74176 2160
18202 88 2N2444 11.91 AD161 87 GET882 25 01.91 07 OC71 12 7400 20 7411 23 7440 20 7483 81-00 74119 /190 74190 11.95
20302 22 282646 46 AF116 26 GJ7M 87 0A211 80 OC72 20 7401 20 7412 42 7441AN 75 7484 90 74121 80 74191 5196
20371 2E 282904 20 AF117 26 K8100A 20 OAZ201 60 0081 20 7402 20 7413 80 7442 76 7486 46 74122 81-86 74192 5800
28404 20 2N2926 10 A8Y28 26 MJE520 87 OAZ207 47 OC81D 20 7403 20 7418 80 7450 20 7490 75 74123 1270 74193 11-00
28697 15 283055 75 BC107 10 MJE2955 oAZ210 82 0082 25 7404 20 7417 80 7451 20 7491AN 6100 74141 8100 74194 19.60
28708 10 283702 10 BC108 10 11-37 oAZ222 46 OC82D 20 7405 20 7420 20 7453 20 7492 75 74145 51.60 74195 0146
2N1132 10 MJE3055 87 OAZ224 46 OC84 25 7408 30 7422 48 7454 80 7493 76 74150 £8-85 74198 11450
25 2N3819 8b BC109
BC169C 15 NKT212 27 0A2241 22 0C170 7407 80 7423 48 7460 20 7494 80 74151 2110 74197 11.60
2N1305 E2 E5
282147 70 AAZ12 80 BF898 28 NKT214 15 OAZ242 88 0C171 30 7408 20 7425 48 7470 30 7495 80 74154 1200 74198 f450
282180 60 AC126 PA BFY50 2E NKT223 33 OAZ240 23 OC200 40 7409 45 7427 42 7472 80 7496 6100 74155 5166 74199 1460
2572218 20 AC127 25 BFY51 20 NKT251 24 OC35 50 OCP71 97 7410 20 7428 60 7473 40 7497 ISM 74156 5165
From 1st April 19973 all orders sub -
TELEX Open to callers 9am 5pm Mon -Sat' V.A.T. c apo your race.
VALVE MAIL ORDER CO 946708 Closed Saturdayfrom m-3 m. lest I P P This must be added to your order

RS T I 6a WELLFIELD ROAD, LONDON SW 16 2BS Send large S.A.E. (or l

Express postage I p per transistor, over 10 post free. Integrated Circuits & Valves Sp, plus I p
nliist.udingPho
77 2424 (4 lines)
6stage.

for each additional item, over £5.00 post free.

TRANSISTORISED F.M. tuner head with A.M. gang, slow

motion drive. 88-108Mcs, with circuit diagram. £2 30p.
PINNACLE LOW NOISE CASSETTES C60 -50p C90-75p
STEREO IC DECODER
'W.W.'
HIGH PERFORMANCE PHASE LOCKED LOOP (as in July '72)
C120-£1. MOTOROLA MC131OP
P -C BOARDS (not computer panels) EX STOCK DELIVERY
1 oft 6 transistors single wave band
Specn. Separation: 40dB 50Hz-15kHz. Distortion: 0:3%. I/P level: 560mV rms.
1 off 4 transistor audio 0/P level: 485mV rms per channel. Input Impedance: 508. Power requirements:
1 off 3 transistor £1 60 the three. 8-12V (g. 16mA. Will drive up to 75mA stereo 'on' lamp or LED.
Encapsulated bridge rectifier (itt usd 3 3mdh) 100 PIV 2 amps. KIT COMPRISES FIBREGLASS PCB
(Printed and tinned), Resistors, I.C., Capacitors, Preset Potm. 6 Instructions.
50p each, 3 for £1-35. Only £3.50 post tree. + VAT.
Transistor F.M. Stereo Multiplex Decoder. Size: 51 x 2-,' x 1=, LIGHT EMITTING DIODE (Red)
As used in well known British stereo units with circuit. £3 75. Suitable as stereo 'on' indicator, for above, with panel mounting clip and
instructions. Only 35p + p.p. +VAT
GARRARD SP25 MK. Il less Cartridge. £1000. MC131OP only £2.77 + PP 6p +VAT
SPECIAL OFFER
10 VOLUME CONTROLS consisting of 2 off each. IN4002100V IA RECT. DIODES. Full SpeciFlcation Devices.
100K log. ganged L'S -20K log. ganged L/S. ONLY 6p each + VAT
470K log, D'P Switch -10K lin. L -S -50K lin. L/S. £1 35. 709' DIL 14 PIN OP AMPS. Full Specification Devices ONLY 34p each + VAT
4 PHONO SOCKETS ON PANEL. 10 panels for £1 25.
12 PLASTIC KNOBS. Chrome and Gold, 3 types -4 off each
Fi -Comp Electronics
-spring clip £1.25. BURTON ROAD, EGGINTON, DERBY DE6 6GY
10 COMPUTER PANELS packed withc omponents inclu-
ding one panel with 2 Power Transistors. £1-00.

LEARN RADIO
SLIDER CONTROLS (less knobs)
25K Log of Lin single 30p.
10K -100K Log ganged 50p.
100K -100K Log ganged 50p.
LIGHT DEPENDENT RESISTORS (RCA sq3536) 30p each & ELECTRONICS AT HOME
4 for £1 00.
CRYSTAL CALIBRATOR No. 10 crystal controlled hetero-
No knowledge needed
build as you learn with
- Extras. Too Is, tran si stors,
meter etc. All supplied.
dyne wave -meter covering 500 KHz-10MHz (harmonics up to the exciting new You could build a
30MHz) power required 300V. DC. 15mA. 12V. 0-3A DC. Test 'Technatron' kit. No radio in weeks.
equipment for 62T MiRC. £2.50 each. SEND FOR FREE 76 PAGE GUIDE TO RADIO/TV,
ELECTRONICS, C & G, TELECOMMS ETC.
ALL ITEMS INCLUDE VAT
All items post paid in GREAT BRITAIN Dept. BPW I7 Aldermaston Court, Reading RG7 4PF
Name

SURPLECTRONICS Address

216 LEAGRAVE ROAD, LUTON, LU3 IJD, BEDS.

1 Age CV BPW17 I
BRITISH INSTITUTE OF ENGINEERING TECHNOLOGY
268

www.americanradiohistory.com
 11.

i
t

Fixing holes
14 dia.

(¡) J \i
517
32 12Vent holes in
base 1/4 dia. 1" 4 67/8

.J l J Lf

112

313/16
3/8h
L
Fig. 27: Cabinet details for the
P.W. Tricolour.

Fig. 28: Details of the base unit for

A
1._f the lamps.
CR-E-3)

Rubber feet

1' 8M

1'- 71/2
3"

Carrying handle

B 1/2x1/2 Slot for cable

B r -i
IºI
_-J L J1-!L _ _
6" 2"
r--
I.,l
A
ro
8/2 9"

,4-- g lJ
Slot for cable
A=1/2 dia. holes clamp. Both
ends
B= 5/32 dia. holes -+

1/8 Chamfer
1111
If(ll
"- 1T1
TIiT
11

T-_¡ 1 13 1 1 111 1 1 PE2

r L7
3/8' Rubber feet
269

www.americanradiohistory.com
 2 rows of 6 holes 'Bron
staggered equal 1/2 pitches
-2.5

65132

1l

Holes in this face of

Chassis to be positioned
from corresponding
holes in Front Panel

1/2

HASSIS

HOLE DATA
Chassis Front Panel
6 holes 14 dio 2 holes 'H'1l8dia
4 holes 'B' 1l4'dia 1 hole 'L' 3/14dia
1 hole'C'3/8dia 3 holes 'M' S/76din
6 holes'D' 1/2 dia 4 holes 'N' 3/g'dia
214.6
11. 1 hole 'E'79/32dia
/16
1 hole'F 11d dia
8 holes'G'1l8dia Csunk
6BA
2 holes' H' 118 dia C'sunk
ONT PANEL
6BA and fit 1l8 dia rivets
4 holes J' made to take Harwin
11132 Captive Spacers or similar
2 holes'K'made to take
6 BA Hanktwshes
5[FPIAI : Chassis 18 S.W G.
aluminium
Front Panel 18or 20
SWG. aluminum

Fig. 29. Front panel and chassis metalwork details for the lamp dimming version. The heat sink is identical to that given in the May issue. Note
that the two holes marked 'K' on the front panel should have been given as 'H'.

using 4BAx14in. bolts and nuts. No insulating washers lights, press on the override switches; the lamps
are used. The heat sink is held in position on the should come on, and if not, change over the lamps,
printed circuit board by 4BAx14in. bolts and nuts. check interconnecting wiring and switching circuits
The lamp dimming controls, VR2, VR3 and VR4 triac and thyristors.
are wired as shown in Fig. 25, the left hand tag on Finally, play some music. If any of the lamps do
each control is unused. These tags should be care- not work, check all the components in the relevant
fully positioned so that they do not touch or short filter circuit for dry joints etc.
to adjacent components.
The Bulgin socket (SKIT) and plug (PL1) are It should have been pointed out in the captions to
numbered on their mouldings to conform with Fig. Figs 24 'and 27 (part 3, last month) that each division
of the graticule scale represented lam. In the list of
20.
components applicable to Fig. 25 the value of Rl
Having completed the units and checked the lamp (page 184) should have been given as 15k12.
wiring to the multiway lamps socket-l-Earth, 2 -
Common, 4 -Bass, 6-Middle and 8-Treble, check if It would appear that in some copies of the May
any of the lamps come on, after the supply has been issue, one of the I.C. connections (IC1) in Fig. 9
switched on. If so, there may be a component was missing. The missing number is '1'. On the same
wrongly positioned in the filter circuit or a solder diagram a figure '13' appears between the middle
bridging around the triac or thyristor. If no lamp and treble outputs. This should be ignored.
270

www.americanradiohistory.com
 Li 9.50 ELECTRONIC DIGITAL CLOCK

TRANNIES
I DOCKYARD, STATION ROAD, OLD HARLOW, ESSEX
(for complete kit of parts including case.)

This 4 digit 24 hour clock is available

to readers at this special price.
Parts would normally cost over £25.
Phone Harlow 37739 Kit of parts includes twelve IC's.
P/P 10p. Price list S.A.E. (Saturday callers welcome) indicators, and a smart white plastic
case.
ALL PRICES INCLUDE VAT

74 Series TTL Electrolytic BARGAIN

0N7400 15p
1 26
15p 8N7423
1
55p
25
60p 8N7450
1
lep
25
15p 8N7489
1 23
8.06p 6.859
Capacitors
8N7401 lep 15p 8N7425 65p 50p 8N7451 lep 15p 8N7490 74p 729
4 VOLT 16 VOLT 40 VOLT PACKS
8N7402 lop 15p 8N7427 49p 489 8N7453 lep 159 8167491 110p 1.04p
8167403 lep 159 2N7428 77p 72p 8N7454 lep 16p 8167492 74p 72D 47µF 6}p 15µF 6}p 47µF 64a
8167404 lep 15p 8N7430 18p 16p 8167460 lep 159 8N7493 74p 72D 100µF 64p 33µF 6}p 100µF 9p
82,174015 lep 16p 8N7432 49p 48p 8N7470 38p 289 8N7494 83p 72p 220µF 64p 68µF 6+p 15OµF 10p Unmarked
8N7406 88p 86p 8N7433 94p 82p 8N7472 88p 29D 8167495 85p 72D
330µF 641s 150µF 8p 220µF Ilp Packs
8N7407 88p 35p 8167437 729 e9p 0N7473 41p 899 8N7496 95p 999
220µF 9p 47OµF 19p
8N7474 41p 88p 8N74100 1.80p 1.76p 1000µF 13p
8167408 20p 189 8N7438 72D 899
17p 680µF 25p Pack of 26
8167409 SOp 18p 8167440 lep ibp 8N7475 50p 479 8N74104 1.09p 1-08p 4700µF 29p 680µF IN4148
8N7410 17p 16p 8N7441 74p 709 8N7476 Np 43p 8N74105 1.09D 1.080 1000µF 17p 1000µF 25p 66p
8N7411 27p 25p 8N7442 74p 70p 8N7480 739 709 81674107 MD 42p 1500µF 25p 2200µF 44p
8167412 88D 859 8N7443 1489 1.37D 8N7481 1.ß2p 1.26p .81,174110 Sip 699 2000µF 43p
8N7444 1.48p 1-87p 8N7482 97p 95p 8N74111 1.37p 1.27p Pack of 10
8147413
8N7418
88p
47p
29p
48p 8N7445 2.00p 1.92D 8N7403 1.20p 1.16p 8N74118 1-10p 1.061) 63 VOLT BC108 55p
8167417 47p 43p 8N7446 1-67p 1.02D 8N7484 110p 1.05p 81674119 1.479 1.879 33µF 6}p BC107 66p
8167420 lep 15p 0N7447 1.039
1.10p 8N7485 3.969 3.86p 8N74121 440 41p 68µF 64p (Plantic can)
8167422 65D 609 8N7448 1.10p
1.08p 5917486 88p Up
8N74122 1.64p 1.489 150µF 64p 25 VOLT
a Devices may be mixed to qualify for Price Breaks 47OµF 11p 10µF 6}p Pack of 10
100 Plus less 10% off 25 plus break 680µF 13p 22µF 6}p Plastic BC109
1500µF 18p 47µF 64p 65p
2200µF I8p 100µF 8p
3300µF 26p 150µF 8p 63 VOLT
Linear Integrated Circuits
Pack of IO
220µF 10p BC169 bap
470µF 13p 22µF 6}p (unmarked)
680µF 20p 4.7µF 64p but tested .
301 DIL 60p 723c DIL 99p
301 T099 56D 723e T099 95p IO VOLT 1000µF 22p 6.8µF 64p
301 8 PIN DIL 46p 741e 8 PIN DIL 98p 22µF 64p 2200µF 39p IOµF 64p 2N2646
30IA DIL 89p 741e 14 PIN DIL 39p 47µF 6}p 5000µF 68p 22µF 64p (unmarked)
301A TO99 699 741e TO911 41p 68µF 10p 88p each
301A 8PIN DIL 88p 747c DIL 48p 100µF 6}p
220µF 8p 100µF 11p
307 DIL 69p 748e DIL 389
307 TO99 699 748c 330µF 10p I50µF 13p Pack of 10
TO99 41p
VOLT 220µF 19p 21629266

308A1458
307
308
ß09c
c
8
TO99
DIL
PIN DIL 88D
8.46D
8'409
86D
1937

3048
DIL
TO99
DIL
1
1
279
279
849
470µF
1000µF
1500µF
2200µF
10p
lip
20p
24p
40
68µF
15µF
33µF
6}p
64p
6}p
330µF
470µF
1000µF
22p
26p
44p
66p
unbranded but
tented
709e TO99 ß1D 7503 DIL 1 27p
Unmarked but fully
tented
MOLLARD POLYESTER'S
Transistors MULLARD POLYESTER CAPACITORS C280 SERIES
4p.01µF, 4}D
1-9
10 plus
2163055
889
279
AC107 18p 100138 369 BF260 299 0044 149 Diodes & 250V P.C. mounting: 0.01 µF, 0016µF, 0.22µF, 8}1).033µF, 0047µF, 0.068µF,
AC126 BC14214p 831) BF329 18p 0045 14p Rectifiers 016µF 022µF, Hp. 0.33µF, 7p. 0.47µF, 9}p.0.68µF, 12p.10µF,149.1 5µF, 029.2.2µF, 270
AC127 BC14318p Sep BF330 18p 0070 Up C296 SERIES FULLY
AC128 BC144189 809 BF390 879 0071 14p 116914 8D MULLARD POLYESTER CAPACITORS MARKED
AC142K BC145229 E8p BFX84 Sep 0072 149 1N918 Sp 400V: 0001µF, 000161,,F, 0.0022µF, 00033µF, 00047µF, 8}p. 0.0068µF,18µ+ ,
0 33µF.
AC141K BC14720p 9p BFX85 Up 0081 149 1N4148 Sp 0.022µF, 0033µF, 85p. 0047µF, 0068µF, 0.1µF, 41p. 016µF, 6}9. 0.22 TYPES
AC176 BC14816p 9p BFX86 229 0083 829 1844 lop 12v. 0.47µF, 14p. ADI61, AD162
AC187 BC149189 9p BFX87 SSD 0084 289 1N4007 28D 160V: 001µF, 0016µF, 022µF, 0099µF, 0047µF, 0068µF, Op. 0112F 81p. 0.115µF, Hp. M/P
AC187K BC153209 18p BFX88 28p TIP29A 689 18113 179 022µF, 6}D. 033µF, S}p. 047µF, 85p. 088µF, 189. 1.0µF, 1419. 1 9 689
AC188 13D BC154 17p BFY50 Sip TIP30A 84p 18120 17p
ACI88K 20p BC157 18p BFY51 17p TIP31A 84p 18121 160 VOLUME CONTROLS 10 plus 689
ACY17 24p BCI58 1ßp BFY52 17p TIP32A 789 18180 0DPotentiometers RECTIFIERS
ACY18 219 BC159 14p BFY64 S9p TIP33 81.16 18131 llp Carbon track 500 a to 2.2M (1 P.I.V. 1 AMP I6 AMP BC107-BC108
ACY19 26p BCI67 18p BFY90 72pp TIP34A 18132 189 Log or Linear BC109
ACY20 2ßp BC168 llp B8X20 19p 6164 18920 8D Single 189. Dual gang (stereo) 449 60 IN40014/p PL4001 8p
1-9 OP
ACY21 28p BC169 llp C407 229 TIP35A 18922 Op Single type with D.P. switch lap extra. 100 IN4002 41p PL4002 Op
10-99 8p
ACY22 18p BC177 16p C426 88p 4868 18923 189 200 IN4003 64p PL4003 lOp
100 plus 81p
ACY39 68p BC179 16p C428 81p TIP38A 18940 Op SLIDE POTENTIOMETERS 400 IN 4004 819 PL4004 lOp
AD140 4Up BC182L 99 C450 17p 6819 AA119 lip 58mm, TRACK 600 IN4005 89 PL4005 189
AD142 449 BC183L 9D MP8111 36p TIP43A 79p AA129 lip SINGLE GANGED, LOO or LIN lk to IM. 800 IN4006 Op PL4006 16p BC 182L:3.4.212-4
AD143 899 BC184L Op MP8112 429 TIP42A 919 AAZ13 119 45p each 1000 IN4007 10p P14007 SOp 1-9 Op
AD149 88p BC186 88p MP8113 86p 2N706 18p AAZ16 149 TWIN GANGED, LOG or LIN 1k to 500k. 10 plue Op
AD150 BOp BC212L llp MP8121 839 2N930 88p AAZ17 14p 88p each.
llp MP8122 2N1131 22p BAI00 18p
86p CARBON SKELETON
AD161 29p BC213L 44p PRESETS
AD162 299 BC214L Ilp MP8123 60p 2N1132 28p BA102 (linear only). BRIDGE RECTIFIERS AC127 or AC128
AD M/P 609 BC258 9p NKT21128p 2N1613 1129 BA115 8p Small high quality typeohms. P.I.V. AMP AMP 6 AMP 10 AMP 1-9 l8p
14p All valves 100.6 meg
1 2
NKT21288p 2N1711 209 BA144 10 plue 12p
229 -I watt
AF114 14p BC259 99 659 each
AF115 14p BC267 14p NKT214 26p 2162904 409 BA145 819 each
50 S8p 68p £1'7Sp 68209 100 plus lip
AF116 14p BC268 169 NKT217 66p 2N2904A BA154 14p -2.5 watt 100 79
AF717 14p BC300 40p NKT261 Sep .44p BAX13 14p VEROBOARD 0.15 0.1 200 87 66Óp 8i589 29.81p
AFI18 92p BC30I 82p NKT27180p 2N2905 48p BAX16 14p Matrix Matrix 400 409 64p 4ß-16p 82'4ßp ZENER
AF124 27p BC302
AF139 88p BC303
AF239 41p BC304
80p
1501,
409
NKT274 26p
NKT276 259
NKT403 71p
2N2924 18p BAY18
2N2926 10p BAY31
2N3053 84p BY100
lop 21in x 31ín
Op 2410 x 610
l9p 3}In x 35ln
19p
28p
28p
ß6D
28D
88p
600
800
44p
491, -
Sep
-
6842 88750
DIODES
400 M/W 6%
AL100 77p BCY70 17p NKT405 839 2N3064 Sfp 817126 18p 3}in x Sin ß8D S2p Miniature
AL102 88p BCY71 87p NKY603F 2N3055 62p BY127 19p Oie x 171e (plain) 949 - BZY 88 Range
AL103 669 BCY72 17p SBp 2N3405 449 BYXIO 24p Vero Pins (bag of 36), 22p THYRISTORS All voltages
ASY26 81D BD123 88p NKT813G 2N3663 67p OAS l9p Vero cutter, 60p; Pin insertion Tools (0.1 and PIV 60 100 200 300 400
A9Y27 40p BD130 SOD 83p 2163702 Op 0.15 matrix) at alp. 33-33 Volt
AU103 99p BD131 88D NKT674 28p 2N3703 Op OA9 lip Amp 28 26 41 44 6S Op each
SLIDE SWITCH 1
AU110 £1.10
AUI11 779
BC107 Op
BD132 90p
BD13b
BD136 60p
NKT677G 2N3704
24p 2N3706
NKT713 82p 2N3706
Op GAIO
99 OA47
Op OA70
84p
Op
8p
SPOT lip each. D.P.D.T. 189 each.
MINIATURE NEON LAMPS
3
7
Amps
Amps -
44 60
98 1.01
80 88
1-24 1 watt 5%
BC108 9p BD14181.87 NKT773 279 2163707 Op
0A73 lip 240V or 110V 1-4 Sp. 5 plus 45p each. All voltage.
BC109 91) BD142 60p 0019 559 2N3708 Op 6.8-200 Volte
BC113 1ót9 BF159 88p OC20 669 2163709 Op 0A79 SD MINITRON DIGITAL RESISTORS 14p each
BC116 169 BF173 29p 0C23 88p 2163710 OpOA81 Op INDICATOR TYPE 3015F } watt 5% carbon 1p each
BC125 18p BF177 28p 0C26 28p 2N3711 9p OARS lip 0-9 and decimals
Reads } watt 10% carbon 1p each
BC126 26p BF178 89p 0028 88p 2163794 17) 0A90 89 (Data Sheet on request) 10 watt 5%
1 watt 10% carbon 2ìp each
BC132 18p BF179 85p 0029 88p 2N3819 BBp
BC134 18p BF194 16p OCIO 389 40361 60p OA91 Sp ONLY L1-50 Range 10 ohm» to 4.7 meg. AU Voltages
7.5-100 Volts
BC135 18D BF195 17D 0038 389 40362 60p OA96 Sp 16 DIL Socket 880 } watt mio 2% Sp each
BC137 18p BF244 27p 0041 14p 40636 60D 0A200 lip Driven by 7447 81.05 Range 10-1 meg ohms 519 each

271

www.americanradiohistory.com
e
FELSTEAD ELECTRONICS (PW 70)
PRACTICAL LONGLEY LANE, GATLEY, CHEADLE, CHES. SK8 4EE

ie WIRELESS
Selection from our List, sent free for stamped addressed envelope. (Free overseas, and
with all orders on request). Cash with order only-No C.O.D. or Caller service. Charge.
(Min. 7p) In brackets alter all items apply to G.B. and Eire only. Regret orders under 309
plus charges unacceptable. S.A.E. please for enquiries or cannot be replied to. Overseae,
ALL including Eire and Channel Ioies, orders lees 10% off prices below, which include V.A.T.
RECORDING TAPE: Finest quality/value British Mylar available: STANDARD 5' BOOft.
SILICON! 40D. 51- 900ft. 65p; 7.1200ft. (18p; LONG PLAY O' 900ft. 669; 54' 1200ft. Up: 7' 1800ft.
21.00 (Charge. for 5' and It', singles 9p, two to four 8p each; five and over 33p the lot.
For 7', one or two lip each reel, 3, 4 and 6 reels 33p the lot. 6 reels and over 39p the lot.)
ELECTRONIC IGNITION SYSTEM Other sizes and accessories in list. CASSETTES, Two types, Both In Library Cases, C60 889.
C90 48p, C120 78p. Deluxe Types: COO 55D, C90 78p, C120 09v. (Charges for both types,
This Capacitor -Discharge Electronic Ignition System was under 5, 9p each. 5 for 170p. All quantities over 5, 889 the lot.)
recently described in Practical Wireless and has proved ex- CARTRIDGES all with standard fittings and etylil. Stereo -compatible Mono GP91/BC
98p; STEREO GP93 61.85, Stereo Ceramic GP94 2176. (All at 7p each.) Comparatives
tremely popular. We are able to offer the kit In two forms; the shown In List, with more type, Inc. Bonotone 9TAIIC, Stereo Ceramic Diamond 2170
standard kit containing the electronic components only, enab- (7p). DIAMOND STYLII: single tip types: Aeon OP37, GP59, GP86/67, GP71, BSR
ling the customer to tailor these to his own layout, or the TC8/LP/ST: COLLABO O.Y. and DC284, GARRARD GC2, OCR, GCS10, OCE12,
RONETTE BF40, O.P, and T. PHILIPS 3301 (3080, 3066, 3302, 3304), 3010/12/13/18,
de-luxe version containing a ready-drilled roller -tinned printed - BONOTONE 19T/20T ALL AT Sep each (7p). SAPPHIRE lOD (7p( DIAMOND DOUBLE
circuit board and fully machined die-cast case with A.M.P TIP TURNOVER TYPES (78 sap. on other side). For ACOS GP73, OP91 (for cartridge.
GP93, GP94 etc.) GP91SC (for stereo compat. type.) GP104 BSR ST4 (ST3, STO), ST9
Electrical Spade Connector Block. Each kit is supplied with a (ST8), ST12/14/15, SONOTONE STA. 9TA, 9TAHC. PHILIPS 3306 3310, 3224, 3228/22
custom wound. transformer, first grade components and full GP280. GARRARD OCM21, and 22, GCS23, 6E825 and 26, OCM21T and 22T, OCM24T
constructional details. OC823. OKS26T and 26T, GCM31, 0C336, OCS36, OCS38, KS40A, KS41B ETC. ALL
AT 08p (7P). SAPPHIRE 889 (7P). DOUBLE DIAMOND STYLII: same die ST/LP tip each
The original circuit employed Germanium Power Transistors ride: no 78) All types 2185 (7p). SAPPHIRE DOUBLE ST/LP, TIPPED 88p (7p).
DIAMOND STYLII GOLDRING REPLACEMENTS: 0800, G800H A 68150, £ßß6 each.
for the negative earth version. WE NOW SUPPLY SILICON G800E, 1175 (8p each). PICK-UP WIRE: super thin flex screened, sheathed, TWIN 7p
P.N.P. POWER DEVICES AT NO EXTRA COST! All per yard, 4 -core 189 per yard (either up to 6 yds. 7p). Over, charges paid. MICROPHONES:
components available separately. Case size 41" x 31" x 2". CRYSTAL: LAPEL 10", clip/hand, lead 3.6mm jack plug 39p (9p). CM20 Cream Plastic
hand 58p (9p); "MIC 45". Curved metal hand grip £110 (11p) ALL with leads. DYNAMIC:
Complete assembly and wiring manual 25p, supplied with de- Excellent Mike, 50K Q, only 32" long, black/chrome, switched, lead with 2.5 and 3.5 mm
luxe kit only, refundable on purchase of kit. Jack plugs 61.87 (8p). Cardiod Ball, 50K/600 n built in volume control, on/off switch, special
20ft lead, the beet value anywhere at £600 (33p); Uni -dir mesh ball 50K/60011 Jack plug
Suitable for 12V systems with Pos. or Neg. earth. cable, adaptor, £6.88 (33p): Omni -dir. Ball mesh, 50K, cable adaptor, jack plug, 6428
(83p each). SPEAKERS: Very popular 12" ROUND, fitted tweeter, 3, 8 or 15 ohms
Price: Standard Kit £7.97 U.K. Post Free (state which) 2&Oe (33p) or pair for stereo £4.66, charges paid. SMALL 21", 3o, 8 R or
De -Luxe Kit £9.62 U.K. Post Free 6411 (state which) 41p (9p). More speakers in List. HEADPHONES: High resistance
2000 n adjustable 2110 (11p). EARPIECES: with lead and min. 2.5mm or 3.5mm (state
Quantity Discounts: which) jack plug. MAGNETIC 18p. CRYSTAL'(3.5mm plug only) 28p (uD to 6 for 9p
Trade and Overseas 1-5 Nett 6-9 Less 10% any size). SOLDERING IRON: Slim, modern, Britiel, high speed, 80", all -min parts replaceable,
highest quality, fully guaranteed £1.29 (11p). TRANSFORMERS: Sub 11 x 11 x
Enquiries Invited 10-49 Less 15% 50-99 Less 20%
30% 12mm. OUTPUT (3 iI for OC72, etc.) 1SD or DRIVER 179 (Up to 12 for 7p). CONNECTING
Mail Order Only 100-999 Less 25% 1000 up Less WIRE: Packs of 5 voile, each coil Oyds. Amts. cols. SOLID CORE 109 (7p(. FLEXIBLE
CORE 18p (9p). RETRACTABLE FLEXIBLE LEADS (CURLIER) with phono plug each
end, or phono plug one end, phono socket at the other (state which) Oft, 80p:SAME 12ft, 539
PLEASE STATE POS. OR NEG. EARTH WHEN (either 7p). VIBRATORS: 12v/4 pin non -synch 121HD4, It" ex. pins, 833, any type). but
ORDERING. 31" ex. pine, USA, 161P. 12v/7 pin synch. (128R7) 21" ex. pins, 789 (9p
MAINS BATTERY ELIMINATORS: Two modele, both 240v A.C. Input. Suit most radios
and cassette recorders/players with front switch, pilot lights, mains and output leads.
DABAR ELECTRONIC PRODUCTS Model SC, 3, O, 71 and 9v 400mA, stabilised with multi -output adaptor £6.60 (35p).
Model N.R. has additional 12v output and 15 500mA £600 (35p).
98A LICHFIELD STREET,
WALSALL, STAFFS. WS1 1LIZ OUR LIST (see heading) has added to the above items Cartridge and Stylii Comparisons
Special Non-re7eatable Offers, Aerial., Dials, Transistors, Multi -Leads, flogs, Sockets
Tel. Walsall 34365 of many types, Speakers, Vol. Controls, Multi -testers, Mike Inserts, Neon., Indicatore,
STEREO Headphones, Pocket Screwdriver Tester., Tel. Pick-ups, Wire, Cable, etc., etc.

Give us six months,

and we'll turn your hobby
into a career.
You have a hobby for a very mathematical genius), have a Lt's quicker and easier to phone, but if you
good reason. It gives you a lot of clear, logical mind and a will to prefer, send this coupon to: Control Data
pleasure. work, then we can train you to be Institute, Wells House, 77 Wells Street,
So if you can find a job that a Computer Engineer inside six
London, W.I.
involves your hobby, chances are months. Please give me further information.
you'll enjoy your work more, and So give us a call. CDI. We're
you'll do better work. the Training Division of one Name
Now CDI can help you find of the world's largest computer
such a job. A job where you'll be manufacturers. And we have the IAddress
responsible for the maintenance experience to know if you can
of a computer installation. A job make it. A ten minute talk with us,
that pays well too. If you're inter- and you could be on the way to
ested in mechanics or electronics spending the rest of your life with I.\ge Phone , PW 7 I
(without necessarily being a your hobby.
I CONTROL DATA CONTROL DATA
Ring INSTITUTE LIMITED

01-637 2171
between 9 a.m. and 9 p.m. and ask for Mr PROUT
The Training Division of one of the world's
largest Computer manufacturers.

272

www.americanradiohistory.com
 THIS IS THE FIRST PAGE
OF THE GREAT BI-PAK SECTION
BRAND NEW FULLY GUARANTEED DEVICES
Type Prier p Type Price p Type Price p Type Price p Type Price p Type Price p Type Price p Type Price p Type Price p Type Price p
AC107 22 AD161 87 13C145 50 BD133 72 BF182 44 MAT120 21 20308 2813053 19 2N4069 11
AC113 22 AD182 87 BC147 11 BDI35 44 BF183 44 MAT121 22 20309 39 2112180 86 2N3054 51 2114080 13
AC115 26 AD161 k BCI48 11 BD136 44 BF184 28 MPF102 98 20339 22 2N2193 39 2N3055 55 2N4061 13
AC117K 22 AD362 (MP) BC149 18 BD137 50 BF185 33 MPF104 41 20339A 18 2N2193 39 2N3391 18 2N4062 13
AC122 13 61 BC]50 20 BD138 55 BF188 44 MPF105 41 20344 20 2N2194 89 2N3391A 18 2N4284 19
AC125 19 ADT140 56 BC161 28 BD139 81 BF194 13 0019 39 20345 18 2812217 24 2N3392 18 2114285. 19
AC126 19 AF114 27 BC152 19 BD148 86 BF198 18 0020 70 2(1371 18 2N2218 22 2N3393 18 28/4288 19
AC127 19 AFI15 27 30163 81 BD155 88 BF196 18 0022 92 20371B 13 2N2219 22 2N3394 18 2N4287 19
AC128 19 AF118 27 30154 88 BD175 88 BF197 18 0023 48 20373 19 2N2220 24 2N3395 19 2N4288 19
AC133 16 AFI17 27 110157 20 BD176 66 BF200 60 0024 82 20374 19 2N2221 22 2N3402 28 2/94289 19
AC134 16 AF118 89 BC158 18 111)177 72 117722 1 05 0025 42 20377 38 2N2222 22 2118403 93 2N4290 19
ACI37 18 AF124 88 BC1S9 18 11121178 72 BF287 50 0026 28 20378 18 2N2368 19 2N3404 81 2N4291 19
AC141 16 AF125 28 BC160 60 1313176 77 BF258 86 0028 55 20381 18 2N2369 18 2113406 46 2N4292 19
AC141S 19 AF128. 81 BC161 66 BD180 77 BF209 94 0029 55 20382 18 2N2369A 18 2N3414 17 2N4293 19
AC142 18 AF127 81 BC167 18 BD185 72 BF262 81 0055 46 20401 33 2192411 27 2113416 17 2115172 13
ACI42K 19 AF139 88 BC168 18 131)186 72 BF263 61 0036 55 20414 83 2N2412 27 2N3416 81 2N5457 35
AC151 17 AF178 88 Bc169 18 BD187 77 BF270 39 0041 22 20417 28 2N2648 52 2N3417 81 2N5458 35
AC154 22 AF179 66 BC170 18 BD188 77 BF271 33 0042 27 2X388 89 2N2711 28 2N3525 88 2N5459 44
AC155 22 AF180 66 BC171 16 BDI89 83 BF272 88 0044 16 2N388A 61 2N2712 98 2113648 10 28301 55
AC156 22 AF181 50 BC172 16 BD190 83 BF273 39 0045 14 2N404 22 2142714 28 2N3702 11 25302A 96
AC157 27 AF188 60 BC173 16 BD195 94 BF274 39 0070 11 2N404Á 81 2M2904 19 2118708 11 28302 46
AC165 22 AF239 41 B0174 16 BD196 94 BFW10 68 0071 11 2X524 46 2N2904A 23 2N3704 12 28303 81
AC766 22 AL102 72 BCI76 24 BD197 99 BFX29 30 0072 16 281537 54 2N2905 28 2N3705 11 28304 77
AC167 22 AL108 78 130177 21 111)198 99 BFX84 24 0074 18 2N598 46 2N2905A 28 2293706 10 28305 93
A0168 27 ABY28 98 BC178 21 B11199 105 BFX85 33 0078 17 2X599 60 2N2906 17 2N3707 12 28308 93
AC189 16 A8Y27 88 BC179 81 1113200 105 BFX86 24 0076 17 281896 14 2N2908A 20 2N3708 8 28307 93
AC178 22 ABY28 98 BCI80 27 1313205 88 BFX87 27 0077 28 2N897 15 2N2907 22 2N3709 10 28321 82
AC177 27 A8Y29 28 BC181 27 1111206 88 BFX88 24 0081 17 219898 27 2N2907A 24 2N3710 10 28322 48
AC178 31 ABY50 28 BC182 11 1111207 1-06 BFYSO 22 00811) 17 2X699 39 2N2923 18 2N3711 10 28322A 48
AC179 81 ABYSS 88 BC182L 11 BD208 105 BFY81 22 0082 17 2X706 9 2N2924 16 2N3819 81 28323 89
AC180 19 ABY52 28 BC188 11 B11Y20 110 BFY62 28 00821) 17 2N706A 10 2112925 18 2N3820 66 28324 77
AC180K 22 ABY64 28 BC183L 11 BF116 27 BFY53 19 0083 28 2X708 18 2N2926(0) 14 2N3821 89 28325 77
AC181 19 A8Y55 88 BC184 18 BF117 50 BPX25 94 0084 22 2X711 33 2112928(7) 12 2113822 81 28326 77
AC181S 22 A8Y66 98 BC184L 18 BF118 77 B8X19 17 00139 22 2X717 89 2N2926(0) 11 2N3903 81 28327 77
AC187 24 ABY67 98 BC188 81 BF119 77 B8120 17 00740 2 2N718 27 2112926(11) 11 2819904 88 28701 48
AC187S
AC188
22
24
AOY58
A8Z21
28
44
BC187
BC207
81
19
BF321
BF129
50
55
B8Y25
B6Y28
17
17
00169
00170
928 2N718A
2N726
55
31
2112926(B) 11
2N3010 77
2N3905
2112906
81
80
40361
40382
44
60
AC188S 22 BC107 10 BC208 12 BF126 60 B8Y27 17 0C171 28 2X727 81 2N3011 16 2N4058 18
ACY17 28 BC108 10 BC209 18 BF127 66 B6Y28 17 00200 28 2X743 22
ACY18 22 BC109 11 BC212L 12 BF152 61 138Y29 17 00201 81 2X744 22 DIODES AND RECTIFIERS
ACY19 22 BC118 11 1102131 12 BF1S3 60 118738 20 00202 31 2X914 18 AA119 9 BY133 23 0A70
ACY20 22 BC114 17 BC214L 18 BF154 50 118739 20 00203 28 2N918 83 AAI20 9 B1164 55 0A79
ACY21 22 BC116 17 BC225 28 BF155 77 1381t40 81 00204 28 2N929 28 AA129 9 BYX88/30 46 0A81
ACY22 18 BC116 17 BC226 89 BF156 68 B8Y41 81 00205 39 2N930 23 AAY30 10 BYZ10 89 OA86
ACY27 20 BC117 17 BCY30 27 BF157 61 1184.95 14 00309 44 2X1131 22 AAZ13 11 BYZll 33 0A90
ACY28 21 BC118 11 BCY31 29 BF158 81 BBY95A 14 OCP71 48 281132 24 BA100 11 BYZ12 83 0A91
ACY29 89 BC119 88 BCY32 33 BF189 88 Bul05 2.20 ORP12 48 2N1302 16 BA116 98 BYZ13 28 0A96
ACY30 31 BC120 88 BCY33 24 BF160 44 C111E 56 ORP60 44 2X1303 18 BA128 24 BYZ16 44 0A200
ACY31 31 BC126 18 BCY34 28 BF162 44 C400 88 ORP61 44 2X1304 19 BA148 18 BYZ17 89 0A202
ACY34 23 BC126 20 BCY70 18 BF163 44 47407 28 P3484 22 2X1305 19 BAI54 18 BYZI8 39 81310
ACY36 23 BC132 18 BCY71 20 BF164 44 C424 22 P397 48 2X1306 23 BA1S5 18 BYZ19 81 8D19
ACY38 91 BC184 20 BCY72 18 BF166 44 0425 55 5T140 14 2X1307 23 BA186 15 0082 18134
ACY40 19 BC136 18 BCZ10 28 11F187 24 47428 39 87141 19 2X1308 28 BY100 17 (OA91 Eq.) 8 1N34A
ACY41 20 BC136 17 BCZ11 28 115173 24 0428 22 T2843 33 2811309 26 BY101 12 , C0651 1N914
ACY44 89 BC137 17 BCX12 28 BF178 39 0441 33 IIT46 30 2X1613 22 BY10S 19 (0A70 -0A79 1N918
AD130 42 BC139 44 BD121 88 BF177 39 C442 33 20301 21 2X1711 22 BY114 18 Eq.) 7 1N414B
AD140 58 BC140 88 BD128 72 BF178 38 0444 39 20302 21 2NI889 86 BY126 18 OAS 89 18021
AD142 58 BC141 88 BD124 88 BF179 88 0450 24 20303 21 2X1890 50 BY127 17 0A58L 98 18951
AD143 42 BC142 88 BD131 65 BF780 33 MAT100 21 20304 27 2X1893 91 BY128 17 OA10 39
AD149 55 BC743 33 BD132 88 BF1H1 33 MATinl 22 2r;306 44 2N2147 79 BY130 18 0A47 8

NEW COMPONENT PAK BARGAINS JUMBO COMPONENT PASS THE NEW S.G.S. EA 1000 AUDIO
Pack MIXED ELECTRONIC COMPONEN TS
No. Qty. Description Price Resistor), capacitors, pots, electroltics AMP MODULE *Guarantee
C 1 250 Resistor. mixed value. approx. count by weight 0.55 and colle plus many other useful Items.
Approximately libe In weight. Prim Incl.
C 2 200 Capacitors mixed values approx. count by weight
C 8
C 4
C
60 Precision Resistors 1% mixed value.
75 0th W Resistor. mixed preferred value.
5 Pieces assorted Ferrite Rode .. ..
..
..
.. 0.55
0.65
0.65
0.65
P. A P. 61-65 only.
Excepllooelly yood refine 3 Watts
C
5
6 2 Timing Gangs, MW/LW VHF .. .. 0-65
R.M.S.
1 Pack Wire 50 metres assorted colours .. .. BRAND NEW
C
C
7
8 10 Reed Switches .. .. .. .. ..
0 55
0.66 ONLY
.. .. .. ..
C 9
CIO
C11
3 Micro Switches
15 Anaorted Pots A Pre -Bets
..
..
5 Jack Sockets 3 x 3.5m 2 x Standard Switch Type.
0.65
0.65
0.66
POST OFFICE
TYPE TELE-
£2.89 each
Module Tested and Guaranteed.
C12 40 Paper Condensers preferred types mixed values .. 0.65
013 20 Electrolytic. Trans. types ..
1 Pack assorted Hardware-Nut./Bolts, Grommets etc...
.. 0.65 PHONE DIALS Qty. 1-9 5289: 10-25 6260 Price each. Larger
quantities quoted on request. Full hook-up diagraºis
C14 O55
.. .. .. .. 0.55 and complete technical data supplied free with each
016
C16
4 Maine Switches, 2 Amp plus
20 Aeaorted Tag Stripe & Panels .. .. .. .. 0.55 ONLY 83p each module or available separately at lop each.
C17 10 Assorted Control Snobs .. .. ..
018 4 Rotary Wave Change Switches .. .. .. .. 0.65
C19 3 Relays 6-24V Operating .. .. .. 0.55
C20 4 Sheets Copper Laminate approx. 10' x 7 .. 0.55
Please add 109 poet and packing on all component packe, plan a further 10p
on pack Nos. Cl, 02, 019 k C20. SYSTEM 12 STEREO
Each Kit contains two Amplifier Mod-
Plus much more- ules, 3 watts RMS, two loudspeakers,
15 ohms, the pre -amplifier, trans-
send now for the former, power supply nodule,
front panel and other acces-
sories, as well as an illus-
BI-PAK "component trated stage-by -stage instruc-
41111

tion booklet designed for the

catalogue" beginner.
5p to cover postage, etc.
Further details available on
request. £18.64 FREE
P. & P.

NOW -TURN OVER FOR MORE FANTASTIC OFFERS

273

www.americanradiohistory.com
 The largest selection KING OF THE PAKS Unequalled Value and Quality QUALITY TESTED SEMICONDUCTORS
NEW LOW PRICED TESTED S.C.R.'s Pak No. Pelee
PIV IA 3.4 6A 6.4 7A l0A 16A lOA tp
TOS T066T066T064T048T048T048T048 NEW BI-PAK UNTESTED QI 20 Red spot traneletore PHI` 0.66
60 0.26 028 0.39 039 0.62 0.66 0.59 1.27 18 White spot R.F. transistors PNP 0.66
100 0.28 0.37 0.63 0.62 0.55 0.84 070 I.54 SUPER PAKS SEMICONDUCTORS Q9
Q2
4 OC 77 type transistor. 0.66
200 0.39 0.41 0.54 0.64 0 89 0.67 0.89 1.78 Q4 8 Matched transistors OC44/45/81/81D 0.56
Money back reload B not satisfied
400 048 052
600 0.59 063
000 0.70 0.77
0.82 062 0.74 0.83 1.09 1.99
0.75 073 0.85 1.07 1.38
0.88 0 88 0.99 1.92 1.66 4.40
- Pak No. Description
QS
Price Q8
Q7
4 OC 76 translator.
6 OC 72 transistors
4 AC 128 translators PNP high gain
0.66
0.66
0.66
ßp Q8 4 AC 126 transistors PNP 0.66
U 1 120 Glass Bub -Min. General Purpose Germanium Diodes 0.65 Q9 7 OC 81 type traneletors 0.66
SIL. RECTS. TESTED Germanium Transistors AF/RF 0.55 Q10 7 OC 71 type traneletors 0.65
U 2 60 Mixec
PIV 900mA 750mA lA 15A SA l0A 30A 0.66 Q11 2 127/128 Complementary pairs
066 U 3 75 Germanium Gold Bonded sub-Min. like OAS, 0A47 PNP/NPN
AC 0
600 04 0 06 0 06 0 08 0.18 0-23 0.65 0.66
1000 04 0.07 008 0 15 0 18 0.28 0.83 U 4 40 Germanium Translators Ilke OC81, AC128 Q12 3 AF 118 type transistors
200 0 08 010 0.07 0.18 0 22 0.27 1.10 U 3 60 200mA Sub -Min. Silicon Diodes 0.56 Q13 3 AF 117 type translators 0.66
400 0.07 0.15 0.08 0.22 0 90 0.41 1.98 U 6 80 Sil. Planar Trane. NPN like BBY96A. 2N706 0.65 Q14 3 00 171 H.F. type transistors 0.66
800 0.08 0-18 0.11 028 0.98 0 60 205 Q15 7 2142926 fill. Epoxy transistor
U 7 18 811. Rectifiers TOP -HAT 750mA VLTG. RANGE up to 10000-56 mixed colour. 0.66
800 0-11 0.19 012 0.28 0.41 0.81 2.20
50 fill. Planar Diodes DO -7 Glus 250mA Ilke 0A200/201 0.65 Q16 2 GET880 low noise Germanium
1000 0.12
1200 -
0.28 0.18 0.39 0 61 0-70
0.37 049 0 89 0 89 - 2 75
--
U 8
U 9 20 Mixed Voltages, 1 Watt Zener Diodes 0'66 transistors
0.65 Q18 4 MADT'B 2 x MAT 100 A 2 lx MAT
40.
0.66
066
U10 20 BAY60 charge etorage Diodes DO -7 Glass
TRIM{ FULL RANGE OF 1711 26 PNP SII. Planar Trane. TO -O like 2N11a2, 2142904 0.66 120 0.66
VBOM 2A MINER DIODES 0.66 Q19 9 MADT'S2 x MAT 101 A 1 x MAT
OA 10A
VOLTAGE RANGE 1112 12 Silicon Rectifiers Epoxy 600mA up to 800 PIV 0.66
0.66 121
TO -5 TO -88 TO -48 2-88V. 400mV (DO.7 1718 30 PNP-NPN Oil. Transistors 0C200 a 28 104 Q20 4 OC 44 Germanium translators A.F 0.65
119 Lp ßp Case) 156 ea. 14W (Top - U14 160 Mixed Silicon and Germanium Diodes 0.66 Q21 4 AC 127 NPN Germanium traneletore 0.66
100 83 65 88 Hat) 20 ea. 10W (80-10 26 NPN 8i. Planar Trans. TO.O like BFY61, 2N867 0.66 Q22 20 NKT transistors A.F. R.F. coded 0.66
Stud) 88v ea. 1716 8111con diodes sub -min 0.66
200 66 66 99 1736 10 3 Amp Silicon Rectifiers Stud Type up to 1000PIV 0.65 Q29 10 OA 202 diodes 0.66
Q24 8 OA 81
400 77 024 121 10 ame POTTED U17 30 Germanium PNP AF Transistor. TO -S like ACY 17-22 0.66 Q20 13 IN914 Silicon diodes 76 PIV 75mA 0.66
0.66 Q28 8 OA96 Germanium diodes cub -min
BRIDGE RECTIFIER U18 8 6 Amp Silicon Rectifiers BYZ18 Type up to 800 PIV 0.66
DIACS 0.96 I1489
on heat sink. U19 26 Silicon NPN Transistors like BC108 Q27 2 l0A PIV Silicon rectifier. I0425R 0.66
FOR UBE WITH 100PIV. 99p each 0.65 Q28 2 Silicon power rectifiers BYZ 19
TRIACB U20 12 1.5 Amp Silicon Rectifier, Top Hat op to 1000 PIV 0.55
0.66 Q29 4 silicon x 2N896,
BR100 (D92) 41v each 1321 90 AF. Germanium Alloy Translators 20300 Series A 0071
0.66 transistors 2 0.66
8 Amp. BRIDGE RECTO. 1729 90 MADT's like MHz Series PNP Translator. Q20 7 Silicon switch translator. 2N708
FREE 60 v RMO 856 each U24 20 Germanium 1 Amp Rectifiers GM Series up to 300 PIV 0.06 NPN 0.66
One 60p Pakyour of 100 v RNA 41p U25 26 900 MHz NPN Silicon Traneletore 214708, BBY27 0.65 Q91 6 Silicon switch traneletors 214708
own choke free with 400 v RHO 61p Ilke IN914 Micro -Min. 0.66 NPN 0'66
CIO 30 Fast Switching Silicon Diodes Silicon transistors 2 x 2N1181,
orders valued £4 or over. Size 16 mm x 18 mm
027 12 NPN Germanium AF Transistors TO -1 like AC127 0.65 Q92 8 PNP 1 x 2N1132 0.55
BRAND NEW TEXAS U29 10 1 Amo SCR's TO.S can, up to 800 PIV CR8l/26-600
1.10 Q39 3 Silicon NPN transistors 2N1711 0.65
GERM. TRANSISTORS
UT 46 UNLTUNCTION
TRANSISTORS M90 16 Plastic Silicon Planar Trans. NPN 2N2926 ....... 0.66 Q94 7 Silicon NPN transistors 2142969,
600MHs (code P397) 0.66
Coded and Guaranteed Direct replacement for VSI 20 Silicon Planar Plastic NPN Trans Low Nolee Amp 2N8707 0.66 Q35 8 Silicon TO -5. 2 x 2N2904 a
T1B 49rand BEN 9000 U32 25 Zener Diodes 400mW DO -7 cane 8-18 volts mixed 0.66 o PN
Pak No. EQVT aleo electrically equiva- 0.66 Q35 7 2143846 TO -18 pleatic 300 MHz NPN 0.65
U93 15 Plutic Cue 1 Amp Silicon Rectifiers IN4000 Serles
T1 203713 0071 lent to 2N2648
90 Silicon PNP Alloy Trans. TO -6 BCY28 28902/4
0.66 Q87 3 2149053 NPN Silicon translators9 .. x
0.96
D1974 0075 25 100+ 1734 NPN 4 x 2263703,
T2 ... 0.66 Q98 7 N 2transistors
1
T8 D1216 00810 0.80 0.28 0.28 1735 26 Silicon Planar Translators PNP TO -18 2N2908 066
T4 203811 0081 1138 20 Silicon Planar NPN Translators TOS BFY60/61/62 066
T6 20882T 0082 0.66
2G944B 0044 U97 30 Silicon Alloy Transistors 80.2 PNP 00200, 283222 ELECTRONIC SLIDE-RULE
TO CADMIUM CELLS
T7
TO
TO
209458
20378 0078
20899A 2141302
0040 ORP12 48e
ORP80, ORP81 44p each
1138
U39
20 Fast Switching Silicon Trans. NPN 400 MHz 2148011
30 RF. Germ. PNP Translators 2141903/6 TO.O
0.66 The MK Slide Rule, designed to simplify Elec-
0 55 tronic calculations teature, the following scaler
0.66 Conver.lon of Frequency and Wavelength.
-
1740 10 Dual Transistor. 8 lead TO -6 2N2080 of L, C and fo of Tuned Circuits.
T10 20417 AF117
U41 26 RF Germanium Transistor. TO-1, °C46, NKT72 0.66 Calculation
Reactance and Belt Inductance. Area of Circle..
All 656 each pik GENERAL PURPOSE
NPN SILICON SWITCH- 1742 10 VHF Germanium PNP Transistors 10-1 NKT887, AP117 0.56 Volume of Cylinders. Resistance of Conductor..
ING TRANS. TO -18 U49 26 Sil. Trans. Plastic TO -l8 A.F. RC112/114 0.66 Weight of Conductors. Decibel Calculation*.
01599 NPN SILICON
SIM. TO 2N708/8. BST - 0'66 Angle Functions. Natural Loge and 'e' Functions.
DUAL TRANSISTOR U44 20 811. Trans. Plastic TO -6 1(0115/118 Multiplication and Division. squaring, Cubing
(Similar to 2N2080) 27/28/96A. All neable 1.10 and Square Roots. Conversion of kW and Hp.
100+ device. no oven or short U48 7 3A SCR. TO88 up to 600PIV
1 25 A must for every electronic engineer and enthusi-
0.28 0.23 circuits. ALSO AVAIL-
0 -NI
ABLE in PNP Sim. to Code No's. mentioned above are given as a guide to the type of device in ast. Size: 22 cm x 4cm. Complete with case and
instructions. Price each: 113.80
2N2906. BCY70. When the pak. The devices themselves are normally unmarked.
ND 120 NIXIE DRIVER ordering please state
TRANSISTOR. preference NPN or PNP.
Suitable replacement for SILICON PHOTO TRAN- INTEGRATED CIRCUIT PANS
Be
BOX 21, C 407, 2N 1899 20 For 065 SISTOR. TO-18 Lens end Manufacturers "Fall Outs" which include Functional and Part-Functional Units.
N PN Blm. to BP X 25 and P21.
120veb.
25 100+ 60 For 110 BRAND NEW. Full data These are classed u 'out-of -epee' from the maker's very rigid specifications, but
1
0.19. 0-17 0.15 100 For 1.02
available. Fully guaranteed. are Ideal for learning about I.C'. and experimental work.
600 For 8.06
Qty. 1.2425-99100 up Pak No. Contents Price
1000 For 1480 Pak No. Contents Price Pak No. Contents Price
Oil. trans suitable for Price each 49p 44p 389
P.E. Organ. Metal TO -18 VI000-1207400 0.65 U1046 -6x7448 0.66 UIC86-607486 0.65
VIC01-12x7401 0.55 01047-6x7447 0.66 111C90-607490 0.66
Eqvt. ZTX300 699 each. OIL. O.P. DIODES Sp ÚI048 -6x7448 0.66 ÚK91 -6x7491 0.65
VICO2-12x7402 0.55
Any Qty. 900mW 30..066 F.E.T.'S 171C09 -12x7409 0.65 VIM) -12x7460 0.66 U1092 -6x7492 0-66
40PIV(Min.) 100. 1.65 2N3810 i10 2615458 360 UIC04-12x7404 0.66 UIC61-1207451 0.66 U1C99-5o7493 0.95
GP 100 TOS METAL Buh -Min. 600 6.60
Full Tested 1,000 9.90 2N8890 659 3615459 44p -
UIC05 12 x 7405 O-66 171063-12x7453 0.55
ÚK64 -12x7454 0.55
Ú1:C94 -6x7494
ÚK96 -6x7496 0.65
0.66
CASE GERMANIUM
Ideal for Organ Builders. 2149821 39 BFW10 88p UIC06-8x7408 0.66
U1096 -6x7498 0.66
Vebo=80V. Viceo=50V. 243823 ilp MPF106 41p UIC07-8x7407 0.66 211080-12x7460 0.56
I.C.-10 amps. Ptot- 1.71C10 -12x7410 0.65 VIC70-807470 0.66 UIC100-6x74100 0.66
30W. hie -30-170. 1.71C19 -8x7419 0.66 02072-807472 0.56 UIC121-6x74121 0.96
Replaces the majority of R 2400 TO8 NNE UIC20-12x7420 0.65 ÚI073 -8x7473 0.65 UIC141 -5 x 74141 0.66
Germanium power Cran SILICON HIGH NEW 6th EDITION VICIO -12x7490 0.66 0I074 -8x7474 0.56 171C161 -6x74151 0.66
sletors In the OC, AD VOLTAGE 01040-1207440 0.66 01076-8x7476 0.66 171C164 -6x74164 0.66
and NKT range. Vebo=250V. Wm.. EQUIVALENTS UIC41-6x7441 O.65 01078-8x7476 0.55 01C199 -6x74199 0.55
I.C.-6 TRANSISTOR
100+ 100V. amps. 171C42 -6x7442 01080-6x7480 0.65 UIC199 -5 x 74199 0.66
Ptot - 30W. hie -typ.20 0.66
1 25 BOOK. A complete croas reference
0.48 0.44 0-40 and equivalent. book for European, VIC49-5x7443 0.66 UIC81-5x7481 0.66
IT =5MHz. 17IC44-6x7444 0.66 211C82 -6x7482 O.6ó UICXI-25 Assorted
25 100+ American and Japanese Transis- 74's 1.55
GP 800 TO8 METAL 0.55
1
0.50 0.44 tors. Exclusive to BIPAK 99p UIC46-5 x 7446 0.66 1.1I083-6 x 7489 0.55
CASE SILICON each. Packs cannot be split, but 25 assorted pieces (our mix) is available as PAK UIC Xl.
Vebo-100V. Vceo=80V
I.C.-15 amps. Ptot-
116W. hie -20. 100fT.-
1MHz. Suitable replace-
ment for 2N 8055,
913055 A LARGE RANGE OF TECHNICAL
AND DATA BOORS ARE NOW
BI -PARS NEW COMPONENT SHOP NOW OPEN WITH A WIDE RANGE OF
ELECTRONIC COMPONENTS AND ACCESSORIES AT COMPETITIVE PRICES -
BDY 11 or BDY 20. 115 WATT SIL AVAILABLE EX. STOCK. 18 BALDOCK STREET (A10), WARE, HERTS.
POWER NPN
0.66
1 26
0.53
100+
0.61 656 EACH
SEND FOR FREE LIST. TEL. (STD 0920) 61593.
OPEN MON. -SAT. 9.15 a.m. to 6 p.m.. FRIDAY UNTIL 8 P.m.
B1P 19/80 TO8 NPN PLASTIC SILICON
ADI6I/162 PNP Vebo-í00V. Vcm=50V I.C.-10 amps. Ptot-SOW. Please add lOp pottage and packing per order. Cash with order
M/P COMP GERM TRANS. hie -typ. 100 il-3MHz HIP 19/20 Matched Pale.
OUR LOWEST PRICE OF 1 25 100+ 1 25 100+ please. Orders to BI-PAK SEMICONDUCTORS, P.O. BOX 6,
OOp PER PAIR 0.879 0.25 0.82 0.60 0.51 0.55 WARE, HERTS.

274
 -the lowest prices!
74 Series T.T.L. I.C's
Bi-PAK STILL LOWEST IN PRICE. FULL SPECIFICATION 1 ¡
BI-PAK DO IT AGAIN!
GUARANTEED. ALL FAMOUS MANUFACTURERS

81(7400
81(7401
0.17
0.17
0N7402 0.17
26
0.18
0.16
0.18
100+ r

0.1881(7460
0 18 8N7451
0.18 81(7463
1
0-17
0.17
0.17
0.16
0.16
0.18
85 100+ 1 25
0.1881(74141 0.74 0.71
0.13 8N74145 £1.85 £1.64
0.1ß18N74160£9-80 £2 97
100 +
0.84
£1.43
22 75
50W pk 25w (RMS)
81(7403 0.17 0.16 0.10 8N7454 0.17 0.18 0.18 8N74151 51-10 £1.05 0.99
8N7404 0.17 0.16 0.13 8N7460 0.17 0.16 0.18 8917415311 82 £1 21 £1 05 01% DISTORTION!
BN7405 017 0.18 0138107470 0.82 0.29 0.2781(74164£1.98 6187 £1.78 HI-FI AUDIO AMPLIFIER
81(7406 0.89 0.84 0.81 81(7472 0-82 029 0.27 81(7416611.54 £1.48 £1.82
81(7407 0.89 0.84 0.8181(7478 0.41 089 0.86 8N74156£1.154 £1.48 £1.82
81(7408 0.20 0.19 0.18 81(7474 0.41 0.39 0.86 8N7415712.09 £1.98 21.87
81(7409 0.20 0.19 0.18 19107476 0.60 048 0.4681(74160£1.98 £1 87 £1.78
81(7410
81(7411
0.17
0.28
0-16
0-27
0.1881(7470 0.44 0.43
0.268N7480 0.74 0.71
0.428N74161111.98
0.8481(7418234.40
£1.87 £1.78
£4.18 £8.85
THE AL50
81(7412
81(7413
81(7418
0-39
0.88
0.48
0.84
0.89
0.44
0.8181(7481 £1.82 £1.27
0.27 81(7482 0 98 0.95
0.4281(7483 8181 11.18
£1.21 8007418214.40
0.94 81(74164 32-48
81.0581(741861248
£4 18 £3.85
£2.87 £2.81
£2 42 £2.87
* Frequency Response 15Hz to
ONLY
81(7417 0.48 0.44 0.428107484 £1.10 £1.06 0.998N74168£ß.85
£8.58 £8.30 100,000-1dB.
81(7420
81(7422
81(7423
0.17
0.65
0.55
0.10
0.58
053
0.1881(7485 £8.98 £3.85
0.50 8N7488 0 35 0.34
0.508N7489 £805 £5.78 £6.51) 8N74176£2
0.88
4242 1281
£8.7481(7417432.63
£1.85 £1.64
7417581-713
£2.64 22.53 * Load -3, or 4, 8 16 ohms.
£3.58p each
81(7425
81(7420
81(7427
056
0.50
0.50
0.58
0.46
0.48
0-605N7490 0.74 071
0.44SN7491 £1.10 £1.05
0-44 8N7492 0.74 0.71
0.6481(7417732.75 £2 64 2253
0.9981(74180£2.20 £1.78 £1.54
0.8481(7418118.05 25.50 £5.93
-

* Distortion -better * Supply voltage 10-35

81(7428 0.77 0.72 0.ß68N7493 0.74 0.71
than .1% at Volts.
0.64 8N7418212.20 £1.98 £1.78
8197430 0 17 0.16 0.13 81(7494 0.85 0.82 0.76 81(7418488.85 23.58 88.80 1 KHz.
81(7492 0.50 0.48 0.44ßN7496 0.86 0.82 0.76ßN74190£2.16 2209 1804
* Overall size 63mm x
81(7433
81(7437
8N7428
0.88
0.71
0.71
0.88
0.88
0.68
0.778007498 0.96 0.93 0.868N74191£ß-09 2804 £1.98
0.6ß8N74100£1.82 2178 £1.718N7419218-1.5 £2.09 22.04
0.6ß8N74104£1.07 £1.04 0.97 8N74193 32-20 2198 £1.98
* Signal to noise ratio 80dB. 105mm x 13mm.
8N7440 0.17 0.16 0.18 8N74106111.07 1104 0.978N74194£2-87 £2.88 £2.75 Tailor made to the most stringent specifications using top quality componente
81(7441 0.74 0.71 0.84ßN74107 0-44 042 0.40ßN74193£2.20 £2.09 £1.98 and incorporating the latest solid state circuitry and ALSO was conceived to 011
81(7442
81(7443
8N7444
0.74
£1.43
£1.48
0.71
£1.88
£1.88
0.648N74110 0-61 0.59 0.66ßN7419631.58 £1.87 1178
£1.82ßN7411111.88 £1.27 £ß.818N74197£1.98 £1.87 £1.76
£1.828N741ß811.10 £1.05 0.99 8N74198113-05 £5.50 14.95
FULLY BUILT - -
the need for all your A.F. amplification needs.
TESTED GUARANTEED.
8N7446 1198 £1.95 ß1.988N7411911.49 21.88 21.21 8N741991606 £5.60 14-96
81(7446 £1.07 £1.04 0.97 81(74121 0.44 0 41 0-88 8 Terminal Poi Volt Reg. TO.3
81(7447
81(7448
£1.10
£1.10
£1.07
£1.07
£1.06 BN74122 21-54 £1 48 £1.81 Plastic O/P 1.6 Amps. µA7806
11.0581(74123£8.08 £2.97 £2.86ßV. & µA7812 13V. 11.78 each
STABILISED POWER
MODULE SPM80
AP80 D especially designed to power 2 of the ALPS
ROCK BOTTOM PRICES Amplifier., up to 16 watt (r.m.s.) per channel simul-
LOGIC DTL 930 Series I.C's taneously. This module embodies the latest components
LINEAR I.C's-FULL SPEC. T7pe Price and circuit techniques incorporating complete short
Pries No. 1 26 100 + circuit protection. With the addition of the Maine Trans-
TM 1(0. 1-24 25-99 100 up BP930 18p 12p lip former MT80, the unit will provide outputs of up to 1.5
BP 2010-8L201C 70p 699 609 BP932 14p 189 129 amps at 35 volte. 810e: 63mm x 105mm x 30mm.
BP7010-81.7010 70p BP933 14p 18p 129 These unite enable you to build Audio Systems of the highest
55p 503 quality at a hitherto unobtainable price. Also Ideal for many
BP 702(x-8L702C 70p 65p 50p BP935 143 18p 123
BP 702-72702 69p 50p BP938 14p 18p 120 other applications including:-Disco Systems, Public Address.
44p BP944 Intercom Units, etc. Handbook available, 10p PRICE
BP709--72709 409 38p 389 14p 18p 12p £3.25
BP 709P-µA7090 40p 88p 339 BP946 289 27p 249
BP 710-72710
BP 711-µA711
603 48p 44p BP948
BP948
13p
280
129
27p
lip
240
TRANSFORMER BMT80 £2.15 p. & p. 28p.
600 98p 44p
BP 7{1-72741 663 609 45p BP961 720 869 810
µA7030 81p 299 27p BP962 18p 12p 110
TAA 268 77p 880 61p BP9093 44p 429 39p STEREO PRE -AMPLIFIER TYPE PA1 00
TAA 298 990 880 77p BP9094 44p 420 890
TAA 860 11.87p £1.74, £1.653 BP9097 94p 423 899 Built to a specification and NOT a price, and yet still the greatest value on the market,
BP9099 44p 429 39p the PA100 stereo pre -amplifier has been conceived from the latest circuit tecunlques.
8.13.8. EA1000 22.900 Designed for use with the ALSO power amplifier system, this quality made unit incorporate.
Devices may be mixed to quality for
quantity price. larger quantity price. no lees than eight silicon planar transistors, two of these are specially selected low noise
on application. (DTL 990 Series only). NPN devices for use in the input stages.
Three switched stereo inputs, and rumble and scratch filters are features of the PA100,
which also has a STEREO/MONO switch, volume, balance and continuously variable
base and treble controls.
SPECIFICATION
NUMERICAL INDICATOR TUBES Frequency Response
Harmonic Distortion
20Hz - 201012 * 1dB
better than 0.1%
Inputs : 1. Tape Head 1.26 mV into 60K L1
2. Radio, Tuper 86 mV into 60K n
- MODEL CD86 GR116 8015F 8. Magnetic P.U. 1.6 mV into 60K
NI Mtpltron All Input voltages are for an output of 260mV. Tape and P.U. input.
MA
Anode voltage (Vdo) equalised to RIAA curve within f 1dB. from 20Ha to 20KHa.

Cathode Current
170mbn 176min 5
All
Batts Control
Treble Control
f 15dB at 20H.
d: 15dB at 20101.
(m.) 2.8 14 8 indicators
Filters : Rumble (High Peas) 100/Is
09 + Decimal
Numerical Height (mm) point. All aid. Scratch (Low Pase) 8KHa
16 18 9
viewing. Full Signal/Noise Ratio
Input overload
-
better than 85dB
+ 26dB
Tube Height (mm) 47 82 22 data for all
types available Supply + 96 volts at 2(1mA
Tube Diameter (mm) 19 18 12 wide on request. Dimensions 292mm x 82mm x 35mm
ONLY£13.15
I.C. Driver Rec. BP41 or BP41 or BP47
141 141
SPECIAL COMPLETE KIT COMPRISING 2 AL50's, 1
SPM80, 1 BMT80 & 1 PA100 ONLY £2530 FREE p. & p.
PRICE EACH 11.87 11.70 11.50
All prices quoted in new pence Giro No. J88-7006
Please send all orders direct to warehouse and despatch department

BI-PAK
RTL MICROLOGIC CIRCUITS DUAL -IN -LIFE SOCKETS.
Price each 14 at 18 Lead Socket. to use with
DUAL -IN-LINE LC's. TWO Range,
Epoxy TO-5 case 1-24 25-99 100 up PROFESSIONAL k NEW LOW COST.
uL900 Buffer 88D 869 29D
PROF. TYPE No. 1-24 25-99 100up.
uL914 Dual 21/p TOO 14 pin type 880 80p 280
gate 88p 889 299 TOO 18 89p 369 889
uL923 J -K flip -Lop 65p 519
Date and Circuits Booklet for IC's
49p
LOW COST No.
BPS 14 17p 153 120
P.O. BOX 6, WARE - HERTS
Price 8p. BPS 16 18p Postage and packing add 10p. Overseas add extra for airmail.
.169 18p
Minimum order SOp. Cash with order please.
Guaranteed Satisfaction or Money Back

275

www.americanradiohistory.com
 ESSENTIAL BOOKS FOR RADIO AMATEURS

These are just four of a complete range of technical publications,

log books and maps for the Radio Amateur. Send s.a.e. for complete list
RADIO SOCIETY OF GREAT BRITAIN
35 DOUGHTY STREET, LONDON, WC1N 2AE TEL: 01-837 8688

BIPRE-PAK BROADWAY ELECTRONICS

MITCHAM ROAD, TOOTING BROADWAY,
92
LONDON S.W.I7 01-672 3984
9TA HIC Diamond [2.47,
CARTRIDGES-Stereo Sonotone
.40, 5106 High Output [I 40, Acos
[I
swami (inclusive of P& P and VAT)
Ponette S105 Medium Output
GP93/I Sapphire L1.95, GP9411 Sapphire [1.95, Japanese equivalent to
B.S.R. TC8s £1 80.
CARTRIDGES-Mono
TC8H lap. equivalent El .29.
GP9I Stereo Compatible [1.29. B.S.R.

* Nominal 12-14V HIFI STEREO HEADPHONES Padded ear

cushions seal out room noise. Perfect coupling
* Distortion typically 0.5% between reproducer and ears assure full response
Power output into 3 ohms=5W, impedance 8 ohms, frequency range 20-20,000 Hz
6ft. cord and standard stereo plug. Only [3.57.
8 ohms =2W,15 ohms =1W
Frequency response at 3dB STEREO HEADPHONE JUNCTION BOX
amplifier and speakers
Simple unit connects direct to
points 10Hz to 30KHz to give attenuated headphone output has 3 position
Sensitivity (with/without tone control) 130mV switch to give headphones only, speakers only,
speakers and headphones. Only £1.74.
* Quiescent current 100mA * Full power 3 ohms (650mA) VYNAIR Widths from 50 to 54in., 9Sp yd. off roll. } yard 57p. Send Sp
This matchbox sized amplifier will run satisfactorily stamps for samples. All prices inclusive of post and packing.
from a 12V car battery. Can also be used for portable
voice reinforcement such as public functions where mains
supply is not accessible. A small mains unit Is available. AUTOMATIC EMERGENCY SUPPLY
Two amplifiers are ideal for Stereo. Complete connection meter. Circuit es
250v 50Hz-150 watt Inverter. Full kit of parts excluding
details and treble, bass, volume and balance control cir- appeared In December P.W. Complete kit -51695 + 80p P. & P.
cuit diagrams are supplied with each unit.
Discounts are available for quantity orders. OTHER INVERTERS AVAILABLE IN KIT FORM
75 Watt-57.50 + sop P. A P.
150 Watt-513.50 + 80P P. & P. 40 Watt -5520 + 40p P. S P.
Built and tested.
900 Watt-L17.90 + 85p P. A P.
Cheapest in the U.M. 25 Watt-521O + 20p P. & f
All above operate from 12v. battery end pine 250v.-50Hz. Output.
volt types are also available, alternative outputs or taps can be supplied.
401..1.I..1. wis..alIJMIMIMIll MIMI III Ile
24
Transformers and/or Transistors can be supplied separately.
enclose £ for amplifiers SPECIAL OFFER
III
1
II secondary
Name 12v. Fluorescent lights, suitable for tente, caravans, houses or post
11
12 Inch -8 watt -53.40 paid.
AddressII , lighting for factories, hotels, etc.
21 Inch -13 watt--54.20 post paid. Large discounts
available for quantities.

BATTERY CHARGER KIT

Dept. D, 222/224 West' Charge
(Consists10 Tr
Transformer and
P.
Rectifier s.)
P.

Rd., Westcliff-on-Sea, 3
!BI-PREPAK Essex, SSO 9DF
I ASTRO ELECTRONICS
`..---.-----_-.-._rie
Co. Regn. Na 820919
Tel: Southend (0702) 46344
6, BARNES ROAD, CHESTERFIELD, DERBYSHIRE

276
 HIGH FIDELITY
MODE
ONE LOUDSPEAKER KIT
Consisting of a Fane Model 803 ultra -low
Recommended resonance 8 speaker unit with PVC cone
retail price surround, and a Fane Model 303 high frequency
pressure tweeter together with a printed
circuit cross -over assembly with ferrite cored
coils.
SPECIFICATION OF UNITS
Model 803 Model 303
including V.A.T.
Overall Diameter
Natural resonance 30Hz
Main resonance 35Hz 1200Hz
Magnet Pole Diameter I"
Magnet Flux Density 13,000 gauss 10,000 gauss
Frequency response 30Hz-8kHz 10kHz-17kHz
Impedance 8-15 ohms 8-15 ohms
Power Handling 15 watts 15 watts

Very easy to assemble, this boxed kit comes

with acoustic foam damping material, panels,
screws, wire, wiring diagrams and instruc-
tions to provide a remarkable loudspeaker
assembly-a pair is ideal for stereo.
CABINETS for the 'Mode One' are available in Teak
finish. SIZE 151" a lOf" x 9".

When used wills above cabinet.

Distributors to the wholesale Manufactured by

Please
send S.A.E and retail trade
for fully LINEAR PRODUCTS LTD.
descriptive Hick Lane, Batley. Yorkshire.
leaflet. Electron Works, Armley, Leeds
LS12 3SA Tel. 630126 Tel. Batley 6431

G. F. MILWARD 369 Alum Rock Road, Birmingham B8 3DR. Tel. 021-327 2339
TRANSISTORS Field Effect Transistors NEW NEWT NEWT NEW!
Output
BD 112
TranslatorsBFW
.. .. .. ..
12113114
25p Mlero-minIature N.P.N.
.. .. .
3.9 An aerosol spray providing e convenient means of producing any number of coples of a
Printed circuit both simply and quickly.
OC 36 .. .. .. .. .. 50P BPS 18R .. .. 10p Method: Spray copper laminate board with light sensitive spray. Cover with trans -
BD 145 .. .. .. .. 20p LDA 400/403/4001412 .. .. 10p parent film upon which circuit has been drawn. Expose to light. (No need to use
Small Signal N.P.N. Infra -red Transmitters Light sensitive aerosol spray ..
...............50p
ultra-violet.) Spray with developer, rinse and etch In normal manner.
.. .. ... .. .. £1.00 plue

i Ii
BC 108.. .. .. .. .. 10p CQY 11A .. .. .. .. E4 Developer end Etchent poestage
BC 109
BF 104 .. .. .. .. .. 100
Llyhtsensitive Tren.. NEWER THAN I »WI 1 VEROBOARD
Transmitting Types OCP 70 .. .. .. .. hp Fibre blast Board pre-treated with light- 2 x lin ..
x 0.151n .. .. Op
senshive lacquer enabl1n9 you to produce 3 x 2 x 0 151n .. .. .. IOp
BFR 64 .. .. .. .. £1 Complementary Drivers, t watts (per Prototype printed circuits within Ove 3ì ln x 3 In x 0151n .. .. .. 20p
BKY 89A .. .. .. .. £5 matched pair) Shp. a pair. x 015in ..
BLY 93A .. .. .. .. E8 minutes. 01n x 2 .. .. 20p
INTEGRATED CIRCUITS 75 mm x 100mm .. .. .. 33p Sin x 3 In x 0151e .. .. .. 28p
Microwave Varactor Diodes TBA 500 Luminance 1.C. . .. LI 150mm x 100mm .. .. SOp 17in x 2 In x 0151e .. .. .. S5p
BOY 27/28/32/35/38/37/38/39/40/41.. Et TBA 510 Chrominance I.C. .. 41 150mm x 200mm .. .. .. £1.32 171n x 3 In x 0151e .. .. .. 74p
FEQ 101 84blt Memory .. ,. LI poxy-Resin 3}in x In x 011n ..
12 .. .. 21p
Microwave Detector 7400 ..
..
..
..
..
.....
,. .. lop 75mm x 100mm .. ..
..
..
..44p22p 3 In x x 011n ..
bin x 2 In x 011n ......239
.. .. 24p
.. ..
.........180 .. 658 100mm x 150mm
..up
CAY 10 .. £0 7401 ..
" 7410 .. .. ,. .. IN150mm x 200mm .. .. Sin x 3 In x 01In .. .. .. 20p
Microwave Mixer
CL 7331 ..
Microwave Gunn Effect Oscillator
CL 8370
CL 8380
CL 8390
..
..
..
..
..
..
..
..
..
..

.. E10
.. £10
.. £10
.. .. £20
7420
7440
7453
7470
7472
7473
14T4
..
..

'
..

.........0p
.. ..
.
..
..
..
.,
..
.. D
Copper -clad Fibre Board
P 121n x 81e .. .. ..
p Copper -clad Epoxy Resin Board
lOIn x Bin .. .. ..
.. 45p

.. 25p
Spot Face Cutter 38p. Pin Insert Tool 40p.
Termine Pine (011 or0.1S) 38 for lip.
Special Offer Pack consisting of 52}In x
lin boards and a Spot Face Cutter-SOP.
"ODDS 8 ENDS"-1p aq In.

CL 8470 .. .. .. .. 440
is MULLCAA POLYESTER ERIE MONOLITHIC CERAMIC
7482 .. .. .. .. .. SSO CAPACITORS CAPACITORS
Microwave Tunnel Diodes
AEY 13.. 7400 .. ,. , ..
500,000 In STOCKIII
:Stir
3p each; 20p dozen; 41.75 per 100

r
.. .. .. .. ES 7491 . . .,. .. .. p 'pplµf 0018µf :015µf 10pí 6801 580pí
AEY 18.. .. .. .. .. 410 7492 . .. .. '001Pµ1 O022µ1 033µf 1501 lOOpi 62001
.. p 012µt 082µf
7493 Npp '0015µf 002791 33sf 220pf 00001
R.F. Transistors 7485 .. .. .. .. .. 0 P dozen; 7Sp-100; k3-1,000; 440.10,000 395f 220Pí 1,00001
BF 180 .. .. .. .. .. 20p

£
p 15µf e8µ1 22µf 30µf 6891 39pí 330pf

Li
BF 194.. .. .. 10p
..
.
.. .. .. .. 475f 470pí
AF .. "" "" .. 20p
6404 1 p 20p dozen; £1-100; 48.50-1,000; £50-10,000
.
CAPACITORS
$RESISTORS
L El
50.qÑS. "ODD PIECES" TRANSISTORSEDUSED
Oc.g2 Ti
DIODES, TRANSISTORSF

i
100 DIODES VERO BC108 ETC. INDUCTORS, RESISTORS
CAPACITORS

e
POSTAGE 159 PACK No. 1 POSTAGE 15p PACK No. 3 POSTAGE lop PACK No. 5 POSTAGE 26p PACK No. 7 I

Li
Í

100 100RESISTORS 1 TRANSISTORISED 100 RESISTORS

C 100CERAMIC TRACER KI 100 CA ACITORS
CAPACITO100 RS
100 POLYSTYRENE
CAPACITORS
50 MULLA RD POLYESTER
TRA NSISTOR
1SIGNAL
SIGNAL INJECTOR KIT
$EDT £11 (ASSOPRTED TYPES)
CAPACITORS CAPACITORS
POSTAGE 15p I PACK No. 2 POSTAGE Isp I PACK No. 4 POSTAGE 15p I PACK No. 8 POSTAGE 15p PACK No. 8

POSTAGE (MINIMUM) 15P PER ORDER ALL GOODS PLUS 10% V.A.T.
277
 Fully guaranteed TRANSISTORS, ZENER DIODES etc. ALL valves
0A5 1N8234 8180 311154 96p BC108 lOp oET116 45p
Individually packed 0410
SOp
259 0072 209 1114785 60p 311159 11 45 BCI13 lOp 0ET116 60p guaranteed
209 0E1168 1140
VALVES oA70
0471
0473
10p 0073
lOp 0075
7p 0076
80p
25p
259
IZMT6
IZMT10
IZT6
859 8FR6
88p 12E1160
87p 40954
46P
78p
BC118
BCY72
8126 8E115
15p NKT222 20p 8J4WA
26p NKT304 60p 635
6J50T
850 ]ciu:
86p 1487
20p 194Q6
85D 6060
70p 6084
40p 6086
50p
46p
65p
B12H 11-76 ECH84 40p 0A2 SOp 0A74 7p 0081 20p IZT10 83p 40596 8126 8E173 209 RA8310AF
80p 0A79 41 26 8E9.51 20p 83D 6J6 18p 1903 8400 6080 8160
CY31 319 ECH200 589 OB2 (6016 00810 Sop 20385 blp 40836 6J70 80p 1906 11-86 6146 2175
DAF98 40p ECL80 389 PABC80 33p lop OC81DM 209 2.0403 61p 40868 11-25 BFY62 SOP 813918 28p
91p 0481 8140 B8 46p 80928 81p 6J7M 35p 19114 14-65 8020 6800
DF98 409 ECL82 Zip PC97 8p 0082 26p 211918 87p 40669
8K60T 45p 20P4 81.00 9001 15p
DK98 489 ECL83 639 PC900 429 0491 75 0C82DM 80p 2111304 229 AC126 26p B82 47p 80038 829
38p 0A200 8D94 21p 8K7 27p 25L60T 85p 9002 Sop
DL92 28p ECL86 88p 7p 0083 2.50. 2N1306 250 AC127 259 BSY29 26p
61170 179 30016 809 9003 46p
DL94 40p EF36 409 PCC89 46D 04202 109 0083B 16p 2111307 269 AC128 209 1311100 gl80 813988 48p
8K80T 32p 30017 660 9004 12p
DL98 40p EF37A 2148 PCC189 4699 04210 0084 259 3E2147 64p AC176 p BYZ13 86p V406A 40p
l0p PCE800
Shp
2E2411 41.60 BYZ16 089 Z2A61CF 789 61126 80p 30018 009 9006 lop
DM70 27p EEG) 04211 80p 00122 50p ACY 17 6L6M 1-85 30F5 88p
DY86 29D EF41 780 PCF80 259 0ÁZ200 66p 00139 26p 2N2904A 26p ACY28 O CR81/10 25D ZR1I 831)
40p 68A7
ZR21 86D 30FL1 65p C.B. Tubes
DY87 28P EF80 22p PCF82 279 0ÁZ201 SOp 00140 40p 2E2989 84.00 AD149 60p CR81/20 38p 68A70T 26p 30FL12 96p VCR97
DY802 48p EF83 49p PCF84 64p OCIO 50p 00170 26p 2E3053 AD161 860 CR81/30 40p ZR22
429
EF85 81p PCFB6 509 AD182 CR81/35 48p 88070T 20p 30FL13 60p 8400
E88CC/01 0022 60p 00171 Bop 2E3054 50p 85p 6867 85p 30F1,14 860
8108 EF86 27p PCF200 80p 0025 40p 00172 2113066 AF118 50p CR81/40 48p 68,07 80p 301.15 86p VCR617B
EF89 259 PCF201 60p 0026 26p 00200 40p 2N3730 60p AF127 20 CR83/06 80p 25 00
E180CC 87p EF91
E181CC 909 EF92
27p PCF801
81p PCF802
40p
46p
0028
0029
80p
609
00201
00206
78p 2E3731
96p 2114172
42 AF1a9
AF178
SOp CR83/20 88p ZENER
48p CR83/30 48p DIODES
68J70T 28p
88117 40p
301.17
30P12
060
86p VCR617C
8700
68L7GT 27p 30P19 86p
E182CC 11F96 81p PCF805 80p 0036 60p 2114 80p 82303 50p AF188 40p CR826/025 All preferred
813N70T 279 30PL1 809 8813 1840
1108 EF183 26p PCF806 609 0036 544 IN25 00p 3E100 B2p A6Y26 25p 55p voltage 88Q7 80p 30PL13 769 88J 8810
EA60 189 EF184 81p PCF808 851) 0038 42p IN43 lop 3FR5 820 A8Y28 9,5p CR83/40 60p 0W 0.17 82p 30PL74 78p 881. 8810
EABC80 279 EFL200 67p PC11200 80p CC44 17p IN70 7p 311128 S7D ASY87 48p C824 059 1W 047 68Q7GT
OM 15p 35Le0T 429
EAF42 469 EL34 46p PCL81 40p 0045 1ßp 1E677 129 3N139 11-76 BAW19 280 CV102 269 1-5W 0.86 BVBOT 829 35W4 80p Photo Tubes
EB91 10p EL41 47p PCL82 80p 0070 12p IN702-726880 3E140 97p BC107 10p GET103 Sßp 7W 0.40 35Z4GT 46p CM620
219 PCL83 509 6%4 2,59
EBC33 45p EL84 1,9 61348 S B%66 25p 5005 46p 6860
87p PCL84 859 PY800 869 UAF42 8-p 3Q4 4 p 64H8
EBC41 460 EL85 p 111785
26p 611E6 20p 6%6GT SOp
i

5001380 46p 931A 44.00

ECC81 81p EL86 889 PCL86 86p PY801 46p UBC41 41p VR105/30 309 384 839 OAKS
81p PCL86 48p QQV03-10 UBF80 86p VR150/3080p 3V4 42p 64118 099 813060 47p 6160 699 5011116 60p 60970
EBF80 36p EL90 18p 8SJ6 86p 6-301.2 70p 76 35p 81800
EBF83 885 EL96 81p PFL200 blp 6110 UBF89 SOp Z800U 81.40 51325451I2 00 64L6 40p
EBF89 27p EL600 78p PL36 459 1117 46p 110085 Up Z801U 61.40 SB/266M SAL5W 85p 6BQ7A 86p 6Z4 80p 76
6800 64516 269 OBR7 76p 7B7 46p 78 40p Special Valves
ECC81 279 EM31 22p PL81 40p 1119 86p UCF80 48p Z803U L110
80 45p CV2339
260 EM80 88p PL82 86p 8TV280/40 1101142 60p Z900T 90p 5ß257M8180 134N8 460 BSW6 66p 7Y4
ECC82 8Ó 723A/B 27-00 118.00
Slp PL83 S8p 8820 U CH81 25p I1,4 189 5R40Y 85P 6AQ6 309 BBW7 801) 9D6
ECC83 27p EM84 2bP 11E2 1270 803 gß-00 JP9/7D
ECC84 27p EM87 82p PL84 80p 8TV280/80 Ú0L82 309 IRS 80p 61140 80p 6AQ5W 469 604
P1.600 820 30p 6V40 87p 8488 SOp 606 80p 12418 25p 805 412-00 83600
ECC85 86p EY61 88p 8220 UCL83 50p 184 47D 12AT7 25P 807 60p 50301 8460
ECC86 40p EY86 86p PL504 82p TT21 8880 UF41 60p 185 20p 5Y3OT 80p 64870 lop WEN
EY81 40p PL608 709 U25 88p U F80 80p IT4 18p 6140 36p 64T6 26p 6CL8 42p 12AU7 84p 813 6400 K300 411-00
ECC88 889 BDB 16p 12AV6 SOD 832A g270 K308 81460
ECC189 47p EY88 40p PL609 90p 026 68p 11E89 30p 1%2A 36p OZI 44p 6A118 SOP
PL802 40p 1112B 45p 5Z4 75p 04X40T 60p 6E48 50p 124%7 26p 8864 80p K337 61460
ECF80 Slp EZ41 46p 74D 027 45p Ú L41
Zip EZ80 225 PX4 1260 60p 111,84 80p 21125 27.60 6Z4OT 88p 64X56T 60p 61,23 60p 12BA6 26p 931A 24-00 K RN2A
ECF82 11191
6E33 8145 1213E6 28p 954 85D 8816
ECF83 67p EZ81 24p PY33 609 0801 70p CUS 55p 3A4 88p 64137 260 6B7 859
25p 6BK7 60p 6110M 189 12BH7 28D 955 20p WL417A
ECF801 580 GZ34 62p PY80 859 UABC80 80p UY41 82p 308 15p 6AC7
958 17p 8185
OZ37 PY81 809 and Special Valves. U.K. 1208 80p
ECF802 68p MANY OTHERS IN STOCK include Cathode Rap Tuber 12E1 1200 967 26p 3J/92/E
ECH36 31p KT68 8188 PY82 28p Postage Up to 41 12p, 81-18 17p, 82-28 22p Over 83 post free. C.O.D. 25p extra. 12115 48p 991 86p 68600
EC1181 25p KT88 12.18 35p 12K7GT 36p 2051 509 50'22 61800
ECB83 86p N78 81.60 PYRE 82p TEXAS INTEGRATED CIRCUIT SN 76131N Stereo 5933 6100 714ÁY 8880
12K8GT 40p
V.A.T. pre -amp EO.OS. VACUUM CONDENSERS 12, 50, 12 711T 80p 8057 46p 7354 81600
A P. 20p. 4,5 and O bank
55pF each 20,000v. £1 -SO. P.
Please add 10% to all 25way unlaelectors, 24V, guaranteed perfect, 63'75;
£807 respectively. MODULATION TRANS-
E4 -SO; Colomor (Electronics) Ltd.
Orders FORMERS made by COLLINS. Freq. resp. 200-5000 170 GOLDHAWK ROAD, LONDON W12.
CPS; Prl. 5000zCT 3000 TV Sec. 60000z 3000 TV Audio RETAIL: 743 4946 TRADE: 743 0899
}Full List of our onvery large power 20W. Et -25. Post and packing 25p. Open 9-12.30, 1.30-5.30 p.m. Thursday 9-1 p.m.
METERS stock of meters request.

GUNTON ELECTRONIC inc.

IGNITION KIT
£9'35 V.A.T.
GLADSTONE RADIO
PRINTED CIRCUIT BOARD DESIGN. ALL METALWORK READY- 66 ELMS ROAD, ALDERSHOT, Hants GU11 1LP
DRILLED
Inc No export. Min. order 50p. Prices include VAT. Closed Wednesdays
READY BUILT UNIT
GUARANTEED 5 YEARS
LI 1.55
V.A.T.
Patents per(ding. 12 volt only-state pos. or neg. earth
Capacitive discharge ignition is recognised as being the most efficient F.Y. TUNER -AMPLIFIER for 88-102 MHz. self -
system and will give you: powered for 200-250v. a.c. double wound mains
* Continual Peak -Tuned Performance trans. Valves ECC85, EF89, EF80, recta. Chassis
* Up to 20v/e reduced fuel consumption 10" x O" x 6'. Audio module output stage giving 3W
* Easier All-weather Starting Into 16 -ohms. Price £14 (p. A P. 66p).
* Increased Acceleration and Top Speed
* Longer Spark Plug Life
* Increased Battery Life MAINS TRANSFORMERS. 240.250v. input. Deduct for more than two trane-
* Elimination of Contact Breaker Burn formers. Trade enquiries invited.
* Purer Exhaust Gas Emission
absolutely everything for assembly: Case, Cables, Coil Con-
B. Charger 12v. at 10A,1389 (20p poet)
E. 250v. at 50 m.a., 4 O -3v. at 10A, 55p (200)
Kit Includes
fitting
nectors, Silicon Grease, etc. 8 page Illustrated Instructions cover S.A.E. H. 90v. at 100m.a., d 220v. at 50m.a. 88p (20p)
of all Types of Tachometers. Call in for a Workshop Demonstration. J. 37v. 2A, 24-0-24v. 150m.a. 8275 (70p
all enquiries please or Phone 33652 (many letters from safisfed customers) K. 250-0-250v. 150m.a. 20v. 4A. 15v. 14. 6-3v. 154. 81.80 (70p)ß
.+"
ALUMINIUM BOXES
Complete with baseplate and screws
M. 110v. input: 200-0-200v. 50m.a. 43v. 1}A, 60p (25p)
P. Interetage, 2 secondaries 6 to 1 + 1 and 5 to 1 42p (20p)ß
Q. 100v. 100ma, 25v. 250ms, O -3v. Al. double shrouded 659 (25p)
R. 230v. 60ma. 8-3v. 204.809 (35p)
8. 260-0-260v. 80ma. O -3v. 254. 75p (35p)
At direct from manufacturer prices with return of post 100 Resistors 0W. A 0W. 27p (10p)
service 100 Silvered Mica 40p (10p)
D Price 110 Diodes AEI - 0002 =0A90 68 (10p)
Type No. L W 100 Ceramica 60p (10p)
7e 54 21 1# 44p 100 High Stabs. 60p (12p
8" 4 4 14 44p } lb Tag strips 2 to 10 way 11 (10p).
9' 4 21 1# 44p 100 8hakeproof washers 4' clear 1.d. 25p (5p)
10° 51 4 11 53p
11 4 2# 2 44p
39p MW/LW TRANSISTOR RADIO
12 3 2 1
Complete set of parte for this MW/LW
13 6 4 2 59p Transistor Radio. Coverage 192-555m +
14 7 5 21 68p 1070-1870m. 9 volt 6 transistor superhet
15 8 6 3 88p using 3 AF117 In RF and IF stage.
16 10 7 3 96p powered by a two stage AF amplISer using
9 x AC128. Output approx. 500MW.
`THESE SIZES ACCEPT STANDARD VEROBOARD Also works off car -aerial. Ply ease, reline
RANGE ALL PRICES INCLUDE V.A.T. covered. Requires PP7 battery, Delee
20% DISCOUNT ON ORDERS FOR 10 OR MORE BOXES 27p extra. 3iio high -quality speaker.
DEPT. Pw 7ELECTRONICS DESIGN ASSOCIATES Price 1800 (40p).
82 BATH STREET, WALSALL WSI 3DE

278
 MAINS MOTOR MULLARD AUDIO AMPLIFIERS DRILL
Precision made -as used In All in module form, each ready built complete with CONTROLLER
record decks and tape recor- heat sinks and connection tags, data supplied. CONTROL
dera -Ideal also for extractor Model 1168 600mW power output 789. NEW 1KW MODEL
fan, blower, heaters, etc. New Model 1172 760mW power output 949.
DRILL Electronically changes
and perfect. Snip at 729. Model EP9000 4 watt power output £1.80, SPEEDS speedf10
rom approxi-
Postage 20p for first one then EP9001 twin channel or stereo pre amp. 61.92 mately rss,
10p for each one ordered. 10% diecount if 10 or more ordered. maximum. Full power at W
speeds by finger-tip control.
Kit includes all part, case.
MUSIC ON TAPE CENTRIFUGAL BLOWER everything and full instruc-
A further buy enables us to offer these at an even Miniature mains driven blower centrifugal type blower tlons. £1d6. iSp post and p.
lower price -namely 85p each or 6 for 12 50. Send unit by Woods. Powerful but specially built for quiet Made up model also available.
for list of titles. We can't repeat when sold out. running-driven by cushioned induction motor with 22.75.
specially built low noise bearings. Overall size 4}" x 43"
BALANCED ARMATURE x 4". When mounted by flange, air is blown Into the MAINS TRANSISTOR POWER
UNIT tic equipment but to suck air out, mount it from centre PACK
500 ohm, operates ae speaker or micro- using clamp. Ideal for cooling electrical equipment or set and ampli-
Designed to operate transistor
so meeful in intercom or similar ÓÓ fitting into a cooker hood, film drying cabinet or for fiers. Adjustable output 6v., 9v., 12 volts for up
rcuitsp87p each, 10 for 18.86.
Dhone, removing flux smoke when soldering etc., etc. A real to 500mA (clam, B working). Takes the place of
bargain at 48.06. any of the following batteries: PPl, PP3, PP4,
CAR ELECTRIC PLUG PPS, PP7, PP9, and others, Kit comprises: malos
Fits in place of cigarette lighter. GOOD COMPANION I.C. VERSION transformer rectifier, smoothing and load resistor,
Useful method for making a quick We can now offer these again In I.C. version tieing Ferranti condensers and instructions. Real snip only 11.10.
connection Into the car electrical 2E414 and Mullard AF Module 1172. Cabinet else approx.
system, 425 each or 10 for 1398. wide x 81n. high x Sin. deep. Complete assembly SWITCH TRIGGER MATS
instructione-Excellent tone wood cabinet 1595 + 25p So thin Is undetectable under
12 VOLT I} AMP poet k Ins. carpet but will switch on
POWER PACK with slightest pressure. For
This comprises double - MIGHTY MIDGET burglar 'alarme, shop doors,
wound 230/2240V mains Probably the t ,lest possible radio, as described in Practical Wireless, January etc.
transformer with full wave '73. All electronic parts 12.20 post paid. 24"x18" 11.54
rectifier and 2000 mF 18" x 10" 1110
smoothing. Price £820,
plus 20p poet a packing. THIS MONTH'S SNIP PP3 BATTERY CHARGER
adjustable from 15-40V in steps -
Heavy Deg Mains Power Pack. Output voltage
maximum
load 250W -that le from 8 amp at 40V to Ióamp
HORSTMAN 24 HOUR TIME SWITCH
With 8 position programmer. When fitted to hot
Almost 3 times the life can be obtained from
PP8 battery if you re -charge It from the mains -
at 15V. This really is a high power heavy duty
unit with dozen. of workshop usen. Output
water systems this could programme as follows:
Programme Hot Water Central Heating
- Ms ready to use charger with Instructions only
5611.
voltage adjustment le very quick -simply inter- o Off Off
change push on leads. Silicon rectifiers and 1 Twice daily Off ISA ELECTRICAL
smoothing by 3,000mF. Price 28.88 plus 85p poet. 2 All day Off
3 Twice daily Twice daily PROGRAMMER
Learn in your sleep:
MAINS RELAY BARGAIN 4 All day All day
Have radio playing and
Special this montn are some single, b Continuously Continuously kettle boiling ae you
double and treble pole change -over Suitable of course, to programme other than central heating and hot water,
for instance, programme upstairs and downstairs electric heating or heating awake switch on
relays. Contacts rated at 15 amps.
Operating coil wound for 240V A.C.
Good British Make. Unused. tility of this Programmer. Mains operated -Size 3" x 3" x 2" deep
Price 1886 each. As illustrated but lees case.
-
and cooling or taped music and radio. In fact there le no limit to the versa-
truders -
lights to ward off in-
have a warm
house to come home to.
Size approx. 14" x 1". Open con- All these and many
etruction. other things you can do
Single pole 28p each 10 for £848 If you invest in an electrical programmer. Clock
Treble pole 89p each 10 for 28.67 PORTABLE ELECTRIC by famous maker with 15 amp. on/oil switch.
DRILL Switch on time can be set anywhere to stay on
MINIATURE Very superior quality made by famous up to 6 hours. Independent 80 minute memory
WAFER SWITCHES jogger. A beautiful unit. Price £2 18 + top P. a A
2 pole, 2 way
3 pole, 3 way
-4
pole, 2 way
-4
pole, 3 way
-
-2
Dutch Toolmaker. Model No. ABM 830.
800w - 2 speed 2200/8000. With 4" chuck and
chuck key, also separate side handle and
or with glees front, chrome bezel, 83p extra.

pole, 4 way -3
pole, 4 way -2pole hammer facility for dealing with concrete, etc. BAKELITE INSTRUMENT
6 way -1pole, 12 way. All at 229 An equivalent British made drill would cost CASE
each. 11600. 11090 -similar model but without the hammer attachment 28.76. Size approx. fit" e 31" x 2"
Have either model on approval for 7 days. deep with brass inserts in four
CONNECTING WIRE corners. This is a very strong case
70078 Copper conductors. 500 metre drams DISTRIBUTION suitable to house Instrumente and
available in the following colours:-Red/Brown - epeclal rigs, etc. Price 505 each.
Yellow - Oreen/Grey - Blue/Green - Red/Orange - PANELS Fixolin lid lip extra.
Green/White - Grey/White - Blue/Orange - Just what you need for work bench or lab. 4 x 13 amp. sockets in metal box to
Brown/Red - Brown/White - Red/Grey - Blue/ take standard 13 amp. fused plugs and on/off switch with neon warning light.
Grey - Blue/Brown. Price £280 per drum plus Supplied complete with 7 feet of heavy cable. Wired up ready to work, 2260 ROCKER SWITCH
40p poet. State alternative colours.
Ditto -but with 200 metres. Price A48 per drum
plus 20p.
plue 20p poet and ins. 13
Size approximately 1" x
10 for 81p.
r
amp self -fixing into au oblong hole.
9p each,

Ditto-but with 100 metres. Price 889 per drum. CAPACITOR DISCHARGE CAR IGNITION
This system which has proved to be amazingly
THERMAL CUTOUT
DOOR SWITCH
As fitted to refrigerators, etc. Switches off se
aim= efficient and reliable was first described In the
Wireless World about year ago. We can supply
kit of parts for an improved and even more efficient
A miniature device f" dim. on one screw fixing
mount --can be used for motor overload protection
door closes. White 175 each. Black 15p earl:. version (Practical Wireless, June). Price £8.64 plus -Ore alarm -soldering iron-switch off, etc., etc.
2up post. When ordering please state whether for positive or negative systems. 15 amp contacte open with flame -radiant or
GOODMANS P.M. SPEAKERS De -luxe model including printed circuit hoard etc. 47.85. conducted heat. lip each or 10 for 99p.
8" x 6" hi flux 15 ohm roil very nwtaºle for use
with Mulford Unilex stereo amplifier or with the 24 -HOUR TIME SWITCH
HONEYWELL PUSH BUTTON
EP9000 on it's own. £166 plan top :, . each. Made by Smiths, these are AC mains operated, NOT MICRO SWITCHES
CLOCKWORK. Ideal for mounting on rack or shelf As used in some vending machines, etc. Each
7" x 4 also 15 ohm and imitable for use with or can be built Into box with 13A socket. Two com- switch Is a change -over type rated at lb amps
the EP9000-not quite 'Itch good quality of pletely adjustable time periods per 24 hour e, 6A 200v A.C. Intended for panel mounting with
course. Price £1.06 each. changeover contacts will switch circuit on or off fixing nuts and single black push knob. Single
during these periods. U-75 past and Ina. 25D. Additional change -over switch 28p. Double switch 42p.
SOIL HEATING KIT time contacts Up pair. Triple switch Sip.

Suitable for garden frame or

propagating shelf, etc. Comprises THYRISTOR LIGHT DIMMER KETTLE ELEMENTS
40 watt mains transformer, heating Made by the femme A.E.I. Co. Complete with
wire, connection strip and in- For any lamp up to 1kw. Mounted on switch plate to et washers and combined fixing ring and plug
sulated wire with connection In place of standard switch. Virtually no radio Interference. shroud. Normal 2 round pin and flat pin earth
diagram. 21.85 plus 20D post. Price 1298, plus 20p poet and Insurance.
Industrial model 6A 28.80. Efb. connection and overload reset push button.
2 Models-ll" (approx.) suitable for Swan and
other similar modele-1I" (approx.) suitable for
DOUBLE ENDED MAINS MOTOR O.E.C., Hotpoint, etc. All quick boil 21Kw
This Is a very quiet running BATTERY CONDITION TESTER elements at 240v. Price 21.88 each.
induction motor, with two Made by Mallory but suitable for all batteries made by
special features -one 1. that It Ever Ready and others, most of which are zinc carbon
has feet for easy fixing and the types but also mercury manganese--mead-silver oxide MAINS TRANSFORMER BARGAIN
other 1a it has a good length of and alkaline batteries may be tested. The tester put a Standard maine 240v input Secondary 2.4v
spindle coming from each end. dummy load on the battery and the meter scale indicates 9 amp intermittent 6 amp continuous. Price 56p.
So It could drive two things at the condition depending upon which section the pointer
once -or with simple slide reste. The section reads "replace" "weak" or "good". The BULGIN 4 PIN PLUG & SOCKET
attachment could reverse direc- tester is complete In It case, size 31" x 65" x 2" with Plug has shielded pin and flex entry and socket
tion. 65p each or 10 for 14-95. leads and prode. Price 22.48 plus 20p postage. for panel mounting. 88p tier pair.
Ditto -but 3 Din -22p per pair.
U.V. LIGHTING SPIT MOTOR
Useful for flaw detection in metals and for looking 200-250v Induction Motor, driving a carter gear box MACLAREN THERMOSTAT
for water marks, etc., also for fitting over tropical with 13" of output drive shaft running at 6 revs per Make and break 20 amo A.C. with the senor
fish tanks. African violet and other Indoor minute. Intended for roasting chicken, also suitable for probe coupled by 2 feet capillary covering range
Plants which must have U.V. for healthy growth.
The outfit comprises of a 12" U.V. tube -choke
starter holder and tube ends. Price 12-20 plus
- driving models -windmills, coloured disc lighting effect,
etc. etc. 12.04 plus 20p post and insurance.
of 10-100oc-complete with large engraved
control knob. Price 88p.
20p poet.
TERMS : 10% discount Il ten of an
80 WATT TUBULAR ELEMENTS
Brass encased with beaded flex ends. Standard
replacements in most absorbtion refrigerators
Ordered, send postage where quoted-other
ter,
others
t tree
t il order
rd f o: th .» It
ü £8 00 J. BULL (ELECTRICAL) LTD
but aleo has dozens of other uses. 28p each or otherwise add SOp. (Dept.
(D P.W.) 7 Park Street, Croydon CRO IYD
10 for 21.48. Callers to: 102/3 Tamworth Road, CROYDON

279
Sinclair Project 60
Now -the Z.50 Mk.2
with built-in automatic
transient overload protection
When originally introduced, the Sinclair Z.50 proved how it was possible to
design and produce a popularly priced modular power amplifier having
characteristics to challenge the world's costliest amplifiers. Many thousands of
Z.50's are now giving excellent service day in, day out. But we have also learned
that constructors do not always use their Z.50's ideally. That is why we have
introduced modifications whereby risk of damage through mis -use is greatly
reduced and performance further enhanced. The Z.50 Mk.2 has improved
thermal stability, more accurately regulated D.C. limiting to ensure more
symetrical output voltage swing and clipping and still less distortion at lower
power. Z.50 Mk.2 is compatible with all other Project 60 modules, and may be
incorporated to advantage in existing systems. Eleven silicon epitaxial planar
transistors are now used, two more than in the original Z.50; circuitry has been
re -designed, making this versatile high performance amplifier better than ever.

Brilliant new with free

Z.30 the power technical specifications manual

£5.48
amplifier for quality and Input impedance 100 Kn
economy Input (for 30w into 8n) 400mV
Signal to noise ratio, referred to full o/p at
30v HT 80dB or better 11IIIIIIMIIIIII1I,III IIII
Distortion 0.02% up to 20W at 80. See curve a
oa
ts+Miiiiiú ru nut
with
free
Frequency response 10Hz to more than
200KHzf1dB
Max. supply voltage 45v (40 to 80 speakers) rr:
mill11111111
1131111111IN
Mtomnrr
1MMI11811111
IIIII
tou wttoeaaut uº
manual (50V 150 speakers only) 001 111111111111111111111/1111 1111
0000
Min. supply voltage 9v
£4.48 Load impedance- minimum 40 at 45v HT
:
0000
0004f1 uu
b a
-
Load impedance maximum safe on open :
H 40
WATTS
1 2

INTO
AM
3

BO
AT
4 510
AT 45V NT
11044
M

circuit

The Z.30 provides excellent facilities for

the constructor requiring a high fidelity
audio system of less power than that
available from Z.50's. Using a power
Typical Project 60 applications
supply of 35 volts, Z.30 will deliver 15
watts RMS into 8 ohms. or 20 watts RMS
into 3 ohms using 30 volts. Total harmonic System The Units to use together with Units cost
distortion is a fantastically low 0.02% at 15 Z.30 Crystal U..12V battery £4.48
Simple battery P.
watts into 8 ohms with signal to noise volume control, etc.
record player
ratio better than 70 dB unweighted. Input
sensitivity 250mV into 100K ohms. Size Mains powered record Z.30, PZ.5 Crystal or ceramic P.U. £9.45
80 x 57 x 13 mm (3}x2*x})Z.30.Z.50 player volume control, etc.
and Z.50 MK.2 modules are compatible
and interchangeable. 12W. RMS continuous 2 x Z.30s, Stereo Crystal, ceramic or mag. £23.90
sine wave stereo amp. for 60; PZ.5 P.U.. F.M. Tuner, etc.
average needs

Guarantee 25W. RMS continuous 2x 2.30s, Stereo High quality ceramic or £26.90
If, within 3 months of purchasing any product direct from sine wave stereo amp. 60; PZ.6 magnetic P.U.. F.M.
Sinclair Radionics Ltd., you are dissatisfied with it, your using low efficiency (high Tuner. Tape Deck. etc.
money will be refunded at once. Many Sinclair appointed performance) speakers
Stockists also offer this same guarantee in co-operation with
Sinclair Radionics Ltd. 80W. (3 ohms) RMS 2 x Z.50s, Stereo As above £34.88
Each Project 60 module is tested before leaving our factory
and is guaranteed to work perfectly. Should any defect arise continuous sine wave de 60; PZ.8, mains
in normal use, we will service it at once and without any luxe stereo amplifier. (60W. transformer
charge to you, if it is returned within two years from the date
of purchase. Outside this period of guarantee a small charge
RMS into 8 ohms)
(typically E1.00) will be made. No charge is made for £19 43
postage by surface mail. Air Mall is charged at cost. Indoor P.A. Z.50, PZ.8, mains Mic., guitar. speakers.
transformer etc., controls

sinIair F.M. Stereo Tuner (£25) & A.F.U. (£5.98) may be added as required.

SINCLAIR RADIONICS LTD., R.O. London Road, St. Ives, Huntingdonshire, PEI7 4HJ (Phone St. Ives 4311) Reg. No. 699483 England
280
 the world's most advanced high fidelity modules
Stereo 60 Pre-amp/control unit Power Supply Units
The new
PZ.8 Mk.3

Designed specifically for use on Project 60 systems, the Stereo 60 is equally suitable for use with any
high quality power amplifier. Since silicon epitaxial planar transistors are used throughout, a really
high signal-to-noise ratio and excellent tracking between channels is achieved. Input selection is by The most reliable power supply unit ever made
means of press buttons, with accurate equalisation on all input channels. The Stereo 60 is particularly available to constructors. Brilliant circuitry makes
easy to mount. failure from over load and even direct shorting of
the output impossible. This is due to an ingenious
SPECIFICATIONS -Input sensitivities: Radio - up to 3mV. Mag. p.u. 3mV: correct to R.I.A.A. curve
±1d B :20 to 25.000 Hz. Ceramic p - up to 3mV Aux - up to 3nrV. Output: 250mV. Signal to noise ratio:
. :
re-entrant current limiting principle which, as far
better than 70dB. Channel matching: within 1dB. Tone controls: TREBLE+ 12 to -12dB at 10KHz: BASS as we know has never before been available in
+12 to-12dB at 100Hz. Front panel brushed aluminium with black knobs and controls. Size: 66 x 40 x 207mm.
: any comparable unit outside the most expensive
laboratory equipment. Ripple and residual noise
have been reduced to the point of almost total
Built, tested andguaranteed. £9.98 elimination. This is, of course, the perfect unit for
Project 60 assemblies, particularly where the new
Z.50 MK.2 amplifiers are used. Nominal working
voltage -45.

Project 60 Stereo F.M. Tuner PZ.8 Mk.3-£7.98

(Mains transformer. if required) £5.98
PZ.5 30v. unstabilised
(not suitable for Project 60 tuner) £4.98
mir-rckrair PZ.6 35v. stabilised
(not suitable fork 12. £7.98

The phase lock loop principle was used for receiving signals from space craft because of its vastly
improved signal to noise ratio. Now, Sinclair have applied the principle to an F.M. tuner with fan-
tastically good results. Other advanced features include varicap diode tuning, printed circuit coils, an
I.C. in the specially designed stero decoder and switchable squelch circuit for silent tuning between
stations. In terms of high fidelity this tuner has a lower level of distortion than any other tuner we
the easy way to
know. Stereo broadcasts are received automatically, a panel indicator lighting up as the stereo signal buy and build
is tuned in. This tuner can also be used to advantage with most other high fidelity systems.
SPECIFICATIONS -Number of transistors: 16 plus 20 in I.C. Tuning range: 87.5 to 108MHz. Sensitivity:
Project 60
71.1V for lock -in over full deviation. Squelch level: Typically 20µV. Signal to noise ratio: >65dB. Audio
frequency response: 10Hz - 15KHz (±1dB). Total harmonic distortion: 0.15% for 30% modulation.
without
Stereo decoder operating level: 20. Cross talk: 40dB. Output voltage: 2 x 150mV R.M.S. maximum soldering
Operating voltage: 25-30VDC.Indicators: Stereo on; tuning. Size: 93 x 40 x 207mm.
Project 605 in one pack contains: one PZ.5. two
Z.30's, one Stereo 60 and one Masterlink, which
Built end tested. Post free. £25 has input sockets and output components
grouped on a single module and all necessary
leads cut to length and fitted with clips to plug
straight on to the modules thus eliminating all
Integrated circuit
Super IC.12 high fidelity amplifier
soldering.
Complete with comprehensive
manual, post free
£29.95
All you need for a superb 30 watt
sistor circuit contained within a 16 lead DIL high fidelity stereo amplifier
package, and the finned heat sink is sufficient for
all requirements. The Super IC.12 is compatible
with Project 60 modules which would be used
with the Z.50 and Z.30 amplifiers. Complete with
free manual and printed circuit board.
Order form
Please send
I enclose cash/cheque/money order.
SPECIFICATIONS
Output power: 6 watts RMS continuous (12 Name
watts peak). 6-811 Frequency Response: 5Hz
to 100KHz±1 dB.Total Harmonic Distortion:
Less than 1%. (Typical 0.1%) at all output
powers and frequencies in the audio band (28V). Address
Load Impedance: 3 to 15 ohms. Input Im-
Having introduced Integrated Circuits to hi-fi pedance: 250 Kohms nominal. Power Gain:
constructors with the IC.10, the first time an IC 90dB 11.000.000,000 times) after feedback.
had ever been made available for such purposes, Supply Voltage: 6 to 28V. Quiescent cur-
we have followed it with an even more efficient rent: 8mA at 28V. Size: 22x45x28mm in-
version. the Super IC.12, a most exciting advance cluding pins and heat sink..
over our original unit. This needs very few ex-
Manual available separately 15p post free.
ternal resistors and capacitors to make an PW7

sinlair
astonishingly good high fidelity amplifier for use With FREE printed circuit SINCLAIR RADIONICS LTD., R.O. London Road,
with pick-up. F.M. radio or small P.A. set up, etc. board and 40 page manual.
The free 40 page manual supplied, details many St. Ives, Huntingdonshire, PE17 4HJ
other applications which this remarkable IC.
make possible. It is the equivalent of a 22 tran-
£2.98 Post free

ADD 10% V.A.T. ON PRICES ON PAGE OPPOSITE AND ABOVE

281
:
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Radio Tel and Electronics Data Book 30p
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SERVICE SHEETS
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Handbook of Simple Transistor Circuits
30p
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RADIO BOOK SERVICE KENSINGTON SUPPLIES (C),

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Sheets (strictly by return of post). Please 355.7.9 Old Road WE BUY New Valves, Transistors and
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SERVICE SHEETS 40p plus S.A.E. * SERVICE SHEET CATALOGUE 20p
OVER 12,000 SERVICE SHEETS& MANUALS IN STOCK ON COLOUR/MONO TELEVISIONS
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NEW BOOKS 8 PUBLICATIONS
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MEN!
£50 p. w.
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How to get the best out of your Tape Recorder. 3rd Edition by P.J.Guy
HOW TO MAKE WALKIE-TALKIES for licensed operation by T.D.Zedd
EASY WAY TO SERVICE RADIO RECEIVERS by L.Sands. 176 pages
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ELECTRONICS FOR THE BEGINNER by J.A.Stanley. 192 pages £1.75 Jobs galore! 144,000 new computer
MECHANICS COURSE IN RADIO, TV & ELECTRONICS 222 (433) personnel needed by 1977. With
FIRST YEAR. Principles and Calculations by B.Fozard £0.50 our revolutionary, direct -from -
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America, course, you train as a
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PART 2. SECOND YEAR. Electronic System9 by G.N.Patchett £0.95 Pay prospects? £2500+p.a.
PART 2. THIRD YEAR. Electronic Systems by G.N.Patchett £2.00 After training, our exclusive ap-
SUBSTITUTION HANDBOOK 12th Edition. 176 pages. by H.W.Sems £1.40 pointments bureau -one of the
world's leaders of its kind -intro-
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NEWNES RADIO & TELEVISION SERVICING books bought & sold (all years) Good prices paid: London Computer Operators
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BELL'S TELEVISION Telephone SERVICES
0423-86844
Telephone: 01-734 2874
127, The Piazza. Dept.M99,
ALBERT PLACE. HARROGATE, YORKSHIRE. Piccadilly Plaza, Manchester I.
Telephone: 061-236 2935

282
 ELEVEN BAND RADIO. SW1-4 (4.30
MHz). Marine. LW, MW, FM. PB
(76-86). Aircraft (108-136). PB (148-174).
Battery/Mains. BFO. AGC. Squelch
Control. Output: 1.3W. 15in x IOin x
512 in, £66. Eight Band Model, with
BFO, £42. Four Band, MW. FM. Air-
craft. PB. £15. SAE. Full Lists. Lang-
tons Radio, High Street, ROCESTER,
Staffordshire, Tel. 388.
TAPE -HEAD reconditioning service.
Guaranteed satisfaction. Send worn
head with £2 to: Sara Electronics,
Fawkham Avenue, Longfield, Kent.
STAND AND INSPECTION magnifiers,
ideal for the inspection of printed cir-
cuits, etc. S.A.E. for list from Revor
Optical, 36 Baker Street, London W.I.

TAPE Send
stamp for lists.

Your talent can earn HEADS

R.D.I. Lt.
Chilton Works,
Garden Rd.,
Richmond,
For valve and

you money! transistorized re-

corders from £2 ea.
Surrey,
TW9 4NS

As a Radio Rentals T.V. Engineer

How's about combining your allowance. PRECISION
hobby with your work? You can What's more, you'll be working POLYCARBONATE CAPACITORS
you know-by joining Radio with one of the friendliest, and Close tolerance. High stability. All 63V d.c.
Rentals to be trained as a T.V. most successful T.V. Rental 0.d7µF: *S% 80p; *2% 40p; *1% 60p
teams in the country. Radio 10µF: *5% 40p; *2% 60p; *1% 60p
Engineer. 22µF: *5% 60g; *2% 600; *1% 76p
You'll certainly be working Rentals, with more branches in 4.7µF: *6% 70g; *2% 90g; *1%81.19
towards a better future with more the U.K. than any other firm. 68µF: *6% 960; *2% 8116; *1%8160
10µF: *6% 81.10; *2% 91.40; *1% 8180
chances of promotion, and have There are vacancies in the 16µF: *5%8160; *2%822.10; .*1%8270
more opportunities to use your London Areas now, to find out TANTALUM BEAD CAPACITORS-
Values available 0.1, 0.22, 0.47, ,0, 2.2, 4.7
talents. all details now ring 675 0191 and
1

6.8µF at 35V, 10µF 25V. 15µF 20V, 22µt`

You'll be well paid, and qualify ask for Mr J. Canning or write ISV, 3311F I0V, 47µF 6V, IOOµF 3V-all
at 9p each; 6 for 50p; 14 for LI. Special pack
either for a company vehicle, or to: Mr J. Canning, Area Liaison 6 off each value (78 capacitors) 85.
alternatively, a generous car Engineer, Radio Rentals, 83 NEWI-TRANSISTORS. BCI07, BCI08,
High Road, Balham, S.W.12. BCI09, All at 9p each; 6 for SOp; 14 for LI. All
brand new and marked. Full spec. devices. May
be mixed to qualify for quantity prices. AF178-
35p each or 3 for ¿Hp.
Radio Rentals POPULAR DIODES 1N914 -7p
50p; 18 for CI. 1N916 -9p each, 6 for SOp, 14
for LI. 1S44-Sp each, 11 for 50p, 24 for LI.
All brand new and marked.
each. 8 for

NEW LOW PRICE -400 mW Zenors

Values available 4.7, 5.6, 6.8, 7.5, 8.2, 91, 10, I, 1

12, 13.5, 15V. Tol. ± 5% at 5 mA. All new and

marked. Price 9p each, 6 for 50p, 14 for LI 00
Special offer 6 off each voltage (66 zeners) L4.25
RESISTORS. Carbon film tW 5%. Range from
Courses Educational 2211 to 2.2M 11 in E l2 series, i.e. 10, 12, 15, 18,
22, 27, 33, 39, 47, 56, 68, 82 and their decades.
High stability, low noise. All at Ip each; Op
RADIO, TV, RTEB Certs., City and for 10 of any one value; 70p for 100 of any one
Guilds, Computers, Radio Amateurs value. Special development pack -10 off each
Cert., Practical Electronics (with kit). value 2.2íl to 2-2M 11 (730 resistors) C5.
Thousands of successes. Details of 440V A.C. CAPACITORS. 0 IµF, size I )in x
home study courses and illustrated tin, 25p; 1125µF, size I tin x fin, 30p; 0.47
LAUNCH INTO A CAREER book-FREE. BIET (Dept ZL BPW 27), and 05µF, size I tin x fin, 3Sp; 1 OµF, size tin
x tin, 45p; 2.0µF, size tin x in, 75p each.
Aldermaston Court, Reading RG7 4PF.
I

FROM YOUR HOBBY Accredited by CACC. SILICON PLASTIC RECTIFIERS 1.5 Amp
Brand new wire -ended 0027. IOOPIV at ep each
or 4 for 30p; 400P1V at 9p each or 4 for 34p;
CIE, AMSE, City & Guilds, etc. 800PIV at 14p each or 4 for 50p.
Thousands of exam successes. Postal Sp post and packing on all orders below CS.
courses in all branches of Engineer- Please add 10% VAT to all orders.
ing. Prospectus FREE. State subject of MARCOTRADI NG (formerly V. Attwood)
Dept.W.6. The Malting., Station Road,
Study for B.Sc. in interest: BIET (Dept ZL BPW 38), Wem, Salop
Aldermaston Court, Reading RG7 4PF.
COMMUNICATION Accredited by CACC.
ENGINEERING at GO TO SEA as a Radio Officer. Write: 5 -N -CHANNEL FETe 3819E-SI
PLYMOUTH POLYTECHNIC Principal, Nautical College, Broad - Full specification devices complete with data and
water, Fleetwood FY7 8JZ. circuit details for building voltmeter, timer, ohm-
meter, etc.
courses commence Send 10p for full list of field effect transistors and
September 1973. Ladders other top quality translators available et bargain
prices.
REDHAWK SALES LIMITED
LADDERS ft £9.80. Carr 80p.
2412
45 Station Road, Gerrard Cross, Bucks.
(Please add 10% V.A.T. to total order). Mall Order only
Leaflet. Home Sales Ladder Centre,
(WLS) Haldane, Halesfield (1) North,
The Senior Registrar, Telford, Salop. Tel: 0952 586644. MINI MAINS PACK KIT. Safe double
wound mini transformer, silicon rects.,
Ref. EE(B), 1000µF smoothing. Delivers 9V d.c.,
Receivers and Components 120mA. Components with data sheet;
Plymouth Polytechnic, TV LINE OUTPUT TRANSFORMERS pack buildable to size of PP6 etc.
PLYMOUTH PL4 8AA. Tidinan Mail Order Ltd., 236 Sandy - battery. £0.90+U.K. post 5p. By mail
combe Rd., Richmond, Surrey. TW9 only from AMATRONIX LTD., 396
SELSDON RD., SOUTH CROYDON,
2EQ. 01-948 3702. SURREY, CR2 ODE.
283
 U.K. ORDERS -ADD VAT TO TOTAL
newts alaaironiK MICROCIRCUITS: 709 28p; 710 36p; 723 S7p;
741 32p; 748 37p; PA230
Amp. LI .62.
70p; SL402A El; FET Op. THE
ALL BRAND NEW, no rejects.
Money back warranty. 5V
DIGITAL INDICATOR. 0-9DP
socket and filter £145. LED
TYPE 0-9DP DIL 22.25 ea.
TRANSISTORS: 2N696 14p; 2N697 14p; 2N706A
11p; 2N 1613 16p; 2N 171 16p; 2N2218 19p;
I

2N2219 19p; 2N2219A 19p; 2N2904 17p; 2N2926

RED 6p; ORANGE 7p; YELLOW 8p; GREEN 9p;
2N3053 ISp; 2N3054 40p; 2N3055 35p; 2N3702
NOW
TEXANON DEMONSTRATION
LIGHT EMITTING DIODES. All 10p; 2N3703 ISp; 2N3704 ISp; 2N3705 9p;
with data and panel clip. 2N3706 9p; 2N3709 8p; 2N3710 9p; 2N371 19p;
TIL 209 I" dia 289. Red 1" dia 2N4058 12p; 2N4059 9p; 2N4061 1Ip; 2N4062
type 88p. Green 759. INFRA I1p; AC107 28p; AC126 lip; AC127 12p; AC176
RED beam LEO 61.10. TBS 15p; ACYI7 23p; ACY2I 17p; AF114 14p; AF115
GAS detector £169. ULTRA- 14p; AF116 14p; AF1I7 14p; AF124 Up; BC107A
SONIC TRANSDUCERS £2. 8p; bC109B 8p; BC109C Sp; BCI25 14p; BC147A
DALO PCB resist marking pen 699. Copper board 9p; BC167A lop; BC168B 9p; BC169B 10p;
12" x 6" SRBP 409 FeC etch PAK 19v. BC177 13p; BC178 lip; BC179 16p; BCY70 ISp; Designer approved Kit only £2850
INTEGRATED CIRCUITS: with data it required. BCY71 22p; BD142 35p; BFI 15 20p; BF194 13p; Instructions only 35p
IC LITE SWITCH: Photo amp/trigger 40ma / 11-20 BFX29 24p; BFX84 20p; BFX86 15p; BFX87 24p;
relay or TTL 87p. Dil relay £110. BFX88 Isp; BFY50 15p; BFY51 15p; BFY52 15p; 80p
BLY47A 40p; BSX20 12p; 0C44 lip; 0C45 lip; Pack 1. RESISTORS
50
IC digital clock OC71 12p; OC72 12p; °C81 I8p; 0083 24p.
ME SERIES AVAILABLE.
RECTIFIERS: Iamp-50V Sip; 100V 4p; 200V
Pack
Pack
Pack
2. SMALL CAPS
3. LARGE CAPS
SUNDRIES
4.
£1
£1.40
£2.50
MOO/LoI type 28 pin 4 or 8 digit 12/24 hr. Chip 41p; 400V 5p; 800V 6p; I,000V 7p.
with socket 119, PCB £189, KIT 62149. 741 Dil Pack SWITCHES
5. £1.00
8 Pin 289, 709 14p, Di] 299, 748 29p, 710 NIP. 555 ZENERS BZY88 SERIES: 2-7V to 33V, 8p each. Pack CONTROLS
6, £1 45
TIMER mono/astable osc. clock 989. REGULA- DIODES: IN916 4p; OA90 6p; OA200 7p; £8.25
TORS: 15A 5 to 20V 2149. 723 37p. Pack 7. SEMI COND.
0A202 Bp. SCR IRI22D (400V 5A) LI -14. Pack 8. TRANSFORMER £4.95
RECEIVER 2N414 61.19. Mini Rx kit 6199. 1310 LED PANEL LAMP with Bush and Data 28p.
stereo decoder for tuners 1289. Kit 2345. CARBON FILM 1W 5% RESISTORS: EI2 values Pack 9. P.C. BOARD £2.50
74E TTL: Gates 7400 etc. 14p ea. 7413 27p. 7441 22G to 2.2MQ Ip each or 7p per 10 of ONE VALUE. Pack 10. CHASSIS, etc £4.20
73p. 7447 1109. 7490 599. 7492 879. 74121 46p. DALO ETCH RESIST FILLED FIBRE TIP PEN 80p.
DIL SOCKETS: lo or hi profile 8/14/16 pin 18p. MINIATURE METAL GLAZE RESISTORS -,W 5/ Post extra-parts available separately
4{p each. Iktl THERMISTOR 9p; 2N3ß 9 26p.
SEMICONDUCTORS
2N3055 40p. BC107 8p. ßC108 8D. BC109 Sp. MEFI04 429. TESTED TRANSISTOR CIRCUITS Send for list and technical spec.
BC147/8/9 lOp. ßC167/8/9 189. ßC177/8/9 lOp. BOOKLET 40p. ITT POCKET MULTIMETER, 27
BC182/3/4 10p. BC212/3/4 11p. BCY70/72 139. es, £17.
ran(Above
prices on April 16th. Check our list.)
Kits also available for
BD131/2 56p. BFY50/51/62 139. TI543 UJT 249.
2N706 lip. 2N2369 129. 2N2928 OY Sp. 2N2648 49p.
JEF ELECTRONICS (P.W.7)
* Radio Control Systems
2N3053 17p. 2N3614 55p 2N3702/3/4/5/8/7/8/9/10/11
AU Sp ea.
York Drive, Grappenhall,
* Digital Clock Systems
PETS: 2N3819 679. 2N3523 299 SCR 400V lA 889.
4A 559. TRANSFORMER: 4A 6 & 12V I1.
York House, 12
Warrington WA4 2EJ * Integrated
50W)
Circuit Amplifiers (to
CAPACITORS: Disc 22pf to 0Q1.i2 4p. 25V electro- Mail Order Only.
lytic 10, 50, 100 µf 3p. 1000 µt 13p.
PRESETS b0 ea. RESISTORS 1W. 5% Up. ea.
C.W.O. P. & P. at cost. ISp min. List free.
* HI-FI Pre -amps
CARBON POTS l2p ea. Dual 40y. Switch + 12p. * Stabilized Power Supply Units
IPZIYoM321 alYa6fßj27ió({p World-wide acclaim, the incomparable
TELERADIO HI Fl, 325 Fore Street,
s1ag812VOLTISDII Me GLOBE-KING Edmonton, London N.9 01-8073719
watt
1:1" n built with diffuser.
fully V.H.F. & S.W. KITS CLOSED ALL DAY THURSDAY
Precision standard, inexpensive, low-cost
valve and transistor Kits for Short -Wave
10-350 m. V.H.F. 80-180 Mks. Ideal for
beginners with unique "Easy-Build" dia-
grams and simplified instructions. Send
to -day for free literature price list and
order form, kindly enclose stamped TREASURE TRACER
addressed envelope (Overseas: Int. Reply
Coupon). Direct to the sole manufacturers: MK III Metal Locator
JOHNSONS (RADIO)
All TRIO equipment available i.e. 9R-5908 Ito SHAW ST., WORCESTER. Venues tuning
Excellent Stetnsity and stability
£4950. JR310 Rx. £75. Aleo CODAR gear 91340 W RI 3QQ Weighs only ffios.
6890. Multiband Rx kit 113-20. CR70A Rs 627-50. Please note new address, city centre. Speke, and . ,ph0n. operation
V.A.T. You most add 10% (1/10) to all prices.
FREE CAT. S.A.E. Data sets. Sp ea, P.EP. 8p CWO.
Pioneers in DX radio -Established for Knocks down to only Inn.
e,.bulo wearch cou et .mbly
P.O. BOX 29, BRACKNELL. BERES'
over 30 years. afinietry .es,oved d.agn
(A JOHN BANNER COMPANY) rhmnuahly professional fini.h
You only new .old.,ldp non. ¢,esedriser
pliere and snips

I
Completely new d.uan
BRAND NEW COMPONENTS by
return. Electrolytics 16V, 25V, 50V- Send axas io.

0.47, 1, 2.2, 4.7, lOmfds.-4p. 22, 47-

COMPUTER PANELS
Type A: 4 Mullard OC35, 4 GET103 etc. bop (5p).
Type B: 3 Mullard 0030 on heat sink, 3 OC76, 6
220 - 6p. (50V -
412p. (50V -5p.) 100-512 p. (50V -7p.)
9p.). Subminiature
bead-type tantalums 0-1/35V, 0.22/35V,
mrameie
Poet 33p 1 -50 sin.,
p

ost 35p d£13.75

OC42 etc. 40p (5p). Type C: 2 Mullard 0C35, 2 0.47/35V, 2.2/35V, 4.7/35V,
1/35V, MINIHITS ELECTRONICS, lab LANGLEY DRIVE, W
LONDON Ell KN.
OC76, 6 OC42 etc. 30p (5p). Type D: 4 Mullard 10/16V -8p. Mylar Film 100V-0.001, (Mail order only)
0C36, 8 OET103 etc. 60p (5p). One of each 1150
(lOp). Parcel of 12 high quality panels, including 0.002, 0.005, 0.01, 0.02-2p. 0.04, 0.05-
power transistors, I.C.'s, tritnpote etc. only 12 (30p). 3p. 0.068, 0.1-312p. Polystyrene 63V.
71b of lower quality 68 (40p). El2 series 10 pf. -1,000 pf. -2p. 1,200 TRANSISTOR AMPLIFIER 80p Vol/
pf. -10,000 pf. -3p. Miniature Highstab Tone Control Panel '75p. 465 K/CS IF
CASED AMPLIFIERS resistors, 5%, E.12 series -Carbon Film Panel 75p. Wavechange-OSC Panel 75p.
13 W 112-10M12 (10% over 1 Meg.)
2 x ECC83, EL84, EZ80 valves on 12 x 5 x 3" Metal Film 14 1012-2.2Mí1 and 1W. LW -MW Rod Aerial 25p. Colour Tele-
chassis in 14 x 13 x 9" cabinet with 7 x 4" 3 B
1/%7
27G-10Mí2 all 34p each. Postage 8p. vision. Croma Panels £3.50. IF Panels
speaker and non-standard single motor tape deck. The C.R. Supply Co., 127 Chesterfield £3.00. EHT Tripler Panel £1.08. Con-
Tested with circuit 68 (£l up to 250 miles, £125 over). Rd., Sheffield S8. trol Panel ON/OFF + Vol/Brightness
Suitable Cassettes £1 (25o). Spare tape heads 409. Controls £1.00. Archer, 9 Pine Grove,
Maidstone, Kent.
71b BARGAIN PARCELS
NEW MODEL V.H.F. KIT MK2
Contains hundreds of components -resistors. Our latest kit. Improved design and performance COMPONENTS GALORE. Pack of 500
capacitors, pots. switches, stale, P.C. boards, tag plus extra amplifier stage, receives aircraft, mixed components manufacturers sur-
stripe, lots of odds and ends. Amazing value at amateurs, mobile, radio 2, 3, 4, etc., this novel plus plus once used. Pack includes
11-65 (35p). little set will give you endless hours of pleasure
and can be butt In one evening. Powered by 9 volt
resistors, capacitors, transistors,
Ferric Chloride, 11b 40p (15p); 101b 6850 (50P). battery, complete with easy to follow instruction diodes, I.C., gang, pots, etc. Tremen-
BC107-9 9p, 12 for £1; 2N3055 85p; 741C 8 pin DIL and built In lack socket for use with earphones or dous value. Send £1 + 10p P & P
or TO99 28p, 10+ 25p; Resistor Packs: 350 Carbon amplifier. C.W.O. to Caledonian Components,
Bop (15p), 100 1 & 2% Hi -stabs 809 (Opt 150 Mixed Only £3.50 +p.&p 10p U.K. only. Fosterton Firs, Strathore Road,
Capacitors 80p (15p). Illustrated catalogue of selected kits and com- Thornton, Fife.
ponents, 20p Inc. VAT. PEP free.
GREENWELD (PW2) ALL PRICES PLUS 10% VAT TRANSISTOR BARGAINS. Similar to
24 Goodhart Way, West Wickham, Kent. Shop at Galleon Trading Co, BC107/8/9, BC168/9, 10 for 30p, 25 for
21 Deptford Broadway S.E.S (next to old cinema).
01-892 8009.
12,Burrs Way,
Corringham,
65p, 50 for £1.05. Individually tested,
SAE list, enquiries. Post in brackets, small parts 3p. Stanford -Le -Hope. unmarked. Post/Package 5p. Mail
All prices exclude VA T. Essex. 5S17 9DE Order only. 7 Walton Dene, Aylesbury,
Bucks.
284
 COMPONENTS AND HARDWARE,
new and used, for P.W. circuits. S.A.E.
TV'S COLOUR TV'S for list. David Coulam, Tathwell,
Louth, Lincs. "AT LAST YOU CAN TRANSMIT AND
Reserviced, perfect working order. repolished.
191n. DECCA £110 FORGET ABOUT LICENCE EXAMINATIONS"
19in. GEC 2028 £115
19in. THORN 2000 £120 because this Ministry approved transmitter/receiver
25in. DECCA £125 Miscellaneous kit does not use R.F. Your transmissions will be
251n. RBM PHILIPS £130 virtually SECRET since they won't be heard by
25in. THORN 2000 £135 conventional means. Actually it's TWO KITS IN
One month comprehensive written guarantee. ONE because you get the printed -circuit boards
These ere cash and collect prices. Delivery and components for both the transmitter AND
quotations by phone receiver. You're going to find this project REALLY

MONO UHF
Fabulous TVs. No rubbish, from good source.
Darned FUN -TO -BUILD with the EASY -TO -FOLLOW
instructions. An extremely flexible design with
quite en AMAZING RANGE -has obvious appli-
cations for SCHOOL PROJECTS, LANGUAGE
Repollshed cabinets. Many working. Recent hang LABORATORIES, SCOUT CAMPS, etc.
slstorised models, incl.:
BUSH TV 14111, TV 166, TV 176
PHILIPS style 70 and 210
PTE & ECKO 866 chassis
Electronic GET YOURS!
'(S.A.E. for details)'
TO: 'BOFFIN PROJECTS
SEND 45.80 (inc. VAT) NOW
'MAIL ORDER ONLY'
THORN 950, 1400, GEC Concorde from
DEPT. KW2010

Wizardry
£12 each
Valve UHF models inc.: 4 CUNLIFFE ROAD
BUSH push-button, THORNE 850, STONELEIGH, EWELL, SURREY
SOBELL, 1000, etc. from £5

U.H.F. TUNERS by Dewtron

Famous kits. e.g. waa-waa complete
For FERGUSON 850, 900 chassis but adaptable kit. £2.95: Fuzz kit £4.75. ante
for most DISTO chassis £2.50 each, cwo postage GLASS FIBRE P.C. BOARD. Large
Included. Send s.a.e. for lists of tubes, tvs, valves,
rhythm modules P & P 20p min.
Ring Modulator modules £8 and supplies available 'in single sided
etc. For England: whole range of synthesiser modules, one ounce copper 2p per 3 sq. inches
TRADE DISPOSALS, 1043 Leeds Road. musical novelties, etc. Catalogue 15p (under 1 foot). '15p per sq. ft. (over
Bradford. Tel. Bradford 665670 from D.E.W. Ltd.. 254 Ringwood 1 foot). 'in double sided one ounce
For Scotland: Road, Ferndown. Dorset. copper 1p per sq. inch (under 1 ft.)
TRADE DISPOSALS, Unit 5, Peacock Cross £1 per sq. ft. (over 1 foot). Please add
INDUSTRIAL ESTATE, 32 Burnbank Road, 10p per sq. foot postage and packing.
Hamilton. Tel. Hamilton 29511/2 We can cut to your size at 1p per cut.
ENGRAVING. Give your Fascia Panels Solid State Lighting The Firs, Small -
that professional look. Have the letters worth Lane, Garboldisham, Diss, Nor-
machine engraved. 3p per letter, folk.
minimum order 50p. Plus P & P.
Colourstones 9 Broadway Close, HARDWARE-Screws, nuts, washers
Harwell, Berkshire. and other useful items in small quan-
VALVE LIST ALUMINIUM SHEET to 'individual
tities. Sheet aluminium to individual
requirements, punched/drilled. Send
ALL VALVES FULLY TESTED 6p for list. Ramar Constructor Services,
sizes or in standard packs, 3p stamp 29 Shelbourne Rd. Stratford-on -Avon,
One valve postage 3p. Over 5' valves for details. Ramar Constructor Ser- Warwks.
postage paid. vices, 29 Shelbourne Road, Stratford
on Avon, Warwicks.
DY86-87 12+p PCF80 5p 6F23 1Sp
EB91
ECC82
15p
10p
PCF86
PCF805
15p
25p
6/30L2
30F5
15p
10p
12 VOLT
ECC85
ECL80
20p
71p
PCL82
PCL83
124p
124p
30E11
30PLI
24p
20p BEDFORD ELECTRONICS
FLUORESCENT LIGHTS
EF80 7 p PCL84 124p 30PL13 1719 As illustrated By Thorn 'AEI
EF183 1 p PCL85 20p MANY MORE
EF184 10p PCL86 174p AVAILABLE 2 Grove Place, Bedford
EH90 15p PFL200 25p S. & W.
PC86 21p PL36 top ELECTRONICS Bedford 51961
PC88 218p PL504 209 114 Burnley
PC900 10p PY800 124p Road YOUR LOCAL
PCC84 Sp PY801 25p Rawtenstall
PCC189 719 U191 1749 Rossendale COMPONENTS SUPPLIER Beat power cuts. Be independent. Ideal
PCC805 15p U26 10p Lancs. for caravans, tents, emergency lighting, etc.
Works anywhere where 12v is available.
Guaranteed for six months. Ready co use at:
MAHE YOUR OWN printed circuits 12 ins. 8 watt E3.86 post paid
kit containing llb etchant, resist, 150 21 ins. 13 watt E4.82 post paid
TUNBRIDGE WELLS, Components sq. in., copper laminate, brush and
from Teleservice, 108Camden Road, instructions -75p. Ferric chloride 21b Callers welcome.
Tunbridge Wells, Kent. Telephone 60p, 4Th £1.00. Copper laminate offcuts, For lists or enquiries, large s.a.e.
31803. useful sizes S.R.B.P. and Fibreglass SALOP ELECTRONICS, 23 WYLE COP
Post
500 sq. in. 80p. 1000 sq. in. £1.37. SHREWSBURY, SHROPSHIRE.
free. C.W.O. Malpas Electronic De-
velopments, 94 Larch Grove, Malpas,
UNUSED RESISTORS and Capacitors Newport, Mon. NP1 6LA. BUILD IT in a DEWBOX quality
250 of each. Including high stabs and cabinet. tin x 212 in x any length.
electrolytics. Only £1.50. Trade en- QUALITY R/P Heads,
12 track D.E.W. Ltd., Ringwood Road, FERN-
quiries invited. 676 Foxhall Road, mounted in Mumetal Case. 55p each. DOWN, Dorset. S.A.E. for leaflet. Write
Ipswich, Suffolk. 117 Herton Road, Brighton BN1 7EG. now -Right now.

NEW VALVES ! GUARANTEED AND TESTED

24 -HOUR SERVICE PRICES INCLUDE VAT ELEKON SPECIALS
IRIS fB 30P19 468 ECC82 Q7 EL33 83 PC1888 44 PY801 .80 ELECTROLYTIC CAPACITORS µF/V :'250/25, 2000/35, 2200/25, 4700/16, 8000/30,
l8IS 23 30PL1 ECC83 21 EL41 .52 PCF801 87 R19 .27 10,000/15, 10,000125, 16 + 16/500, 1030 + 1000/40. All at 8óp each, post tree.
1T4 18 DAF91 28 E0085 81 EL84 20 PCF802 438 095 488 16 + 16/350. 32 + 16/350, 40 + 40/260, 50 + 50/300, 80 + 80/450, 100 + 100/385.
384 .28 DAF96 36 ECH35 48 EM80 86 PCF805 56 U26 64 All at 25p each, post tree.
3V4 .46 DF91 18 F61142 56 EM81 -86 PC182 28 0191 54 2000/30, 2500/50, 5000/50, 10,000/50, 12,50000. 80p each, post free.
6130L2 48 DF96 .36 ECHBl .80 EM84 80 PCL83 53 U251 .80
6AT6 18 D1177 18 ECL80 .87 13E88 437 PCL84 31 U329 85 VI800NOL ENT CAPACITORS. 'O01µ1'' 20KV 50P. -01µF fiKl' 409, 'COME 10E,
6AQIS 438 DK91 28 ECL82 .II7 EZ80 19 P(II.85 36 UABC80 29 50p, 02µF 5KV 40p.
6BW7 48 DK96 .43 ECL86 .39 EZ81. 21 PLZ86 35 1JBF89 88
6E1 -67 DL92 28 EF39 .48 KT61 83 PFL200 45 UCC86 82 BUBTs YETALLISED FILM REVERSIBLE ELECTROLYTIC CAPACITORS
6F'23 DL94 .40 EF4I 58 KT66 76 PL36 45 UC1142 .68 8µF 63V Type ML 30 wire -ended, 259 each. Also 10µF 63V, same price.
6E25 49 DL96 .36 EF80 22 N78 61.00 PLO! 41 UCH81 28
I2AU7 17 DY86 21 EF85 .26 PC86 42 PL82 29 UOLB-' 30 SOKSOL DE -SOLDER BRAD). 9ft length 50p, 20 It length 81.00.
251.60T 18 DY87 .21 EF86 .97 PC88 .42 PL83 31 UF41 49
30015 .68 DY802 38 EF89 -94 PC97 84 P1,84 28 11F89 28
BUBMIl1IAT UBE PLUG-IN CRYSTALS FOB RADIO CONTROL. 26.985MHz and
EABC80 16 PC900 27.025 MHz. 70p each.
30017 .73 EF91 .28 .28 PL600 58 UL41 52
30018 55 EBC33
43 EF92 .gg PCC84 97 P1.504 58 UL84 27
30F5 .60 EBC41
.47 EF183 B6 PCC89 41 PY81 23 UY41 137
ADD 10% l'.A.T. TO TOTAL ORDER.
30FL1 -69 EDEN)
-27 EF184 .87 P1x189 46 PY82 23 UY85 22
30FL14 138 E(,tBI .15 EH90
Poet/Packing on 1 valve 7p. plus 3p.
.88 PCF80 25 PY800
per valve on each extra valve.
against damage io transit 3p. extra. Office addreee, no Wlere.
30 W77 42
Any parcel insured ELEKON ENTERPRISES
GERALD BERNARD 83 Osbaldeston Road, 224a St Paul's Road, Highbury Corner, London N.1
Stoke Newington, London N.I6

285
 tefiludeineei For CAR-CARAVAN-BOAT
LOUDSPEAKER elffloommimmit Stabilised 6, 7.5 & 9v from single unit. Battery operated
cassette recorders, radios etc., powered by 12v car
battery through this ingeneous electronic Adaptor. Con-
BARGAINS stant stabilised power means apparatus in use Is always
working at maximum efficiency-and no more 1.5v, 9v etc
batteries to -buy. Only £3.95 (p.p 12g).
Fane Pop 100 watt 18" 8315 ohm £21.45 FOR THE HOME: Voltage Converters 220-240v AC to 6, 7.5
Fane Pop 60 watt 15" 8/15 ohm £12.26 3 9v DC: 2.00mA £2 50, 400mA £3.00. Leads (optional) 50p
Fane Pop 50 watt 12" 8/15 ohm £10.17
STABILIZED (State plug required). All prices include VAT.
Fane Pop 25/2 25 watt 8/15 ohm £5.94
Fane Pop 15 12" 15 watt 8/15 ohm £4.40
AUTO ADAPTOR ry ardens Hove Sussex
Fane 122,110a or 122/12 .. £9.90
Fane Crescendo 15" 8 or 15 ohm £27.50
Fane Crescendo 12" 8 or 15 ohm £24.20
Fane 8" d/cone 808T 8 or 15 ohm £2.64
Fane 8" dlcone, roll surr. 8071
8 or 15 ohm ... ... ... £3 16 AERIAL BOOSTERS-í.3r25 AUDIO POWER
Baker Group 25 3, 8 or 15 ohm
Baker Group 35, 3, 8 or 15 ohm
£6-00
£7.50
We make three types of Aerial Boosters: 845-
U HF 025, B12 -VHF 405, B11 -VHF RADIO AMPLIFIERS
Baker De Luxe 12" dlcone ... £9.62 VALVE BARGAINS
Baker Major
EMI 13 x 8 3, 8 or
..
15 ohm
... £7 -SO
£2.25 ANY 5-SOp, 10-75p, 50-£330:- 10W - £4-00 1

EMI 13 x 8 type 150 dlcone 3, 8 or

£2 58
ECC82, ECL80, EB91, EBF89, EF80, EF85, EF183,
EF184, EY86, PCC84, PCC89, PCC189, PC97,
PCF80, PCF86, PCF805, PCF808. PCL82, PCLB3, 25W - £8-00 OF F
EMI

EMI
15
13
ohm ...
13
...
x 8 type 350 8 ohm
-...
x 8 type 450 t'tve 3, 8 or
...
£3-85
£8.25
PCL84, PCL85, PFL200, PL38, PL81, PL504, PY33,
PY82, PY800, PY801, 30L15.

19" UHF/VHF (BBC2) £6.00

50W - £11-00 PRICES
...
EMI
Elac
64" 93850 4 or 8 ohm
9 x 5 59RML09 15 ohm ...
£2-80
£2.52 Thorn -850 or Pye, with set of spare valves. GENEROUS QUANTITY
Elac 9 x 5 59RMLL4 8 ohm ... £2-53 Carriage £200 (Untested). DISCOUNTS AVAILABLE
Elac 64" d/cone 6RM220 8 ohm ... £2.59
100 MIXED RESISTORS -65p
Elac 64" dlcone, roll surr. 6RM171 above 1m -ohms (our
it to 2 watt -10 ohms to
DETAILS FROM:
£3.22
8 ohm
Elac 4" tweeter TW4 8 or 15 ohm LI21 choice) 100 mixed CapacItors up to 500MFD-
L1`10 (our choice).
PHOTAIN CONTROLS LTD.
Celestion PS8 for Unilex ... £2.16 Randalls Road, Leatherhead, Surrey
Celestion MFL000 25 watt horn BARGAINS PARTS
8 or 15 ohm ... ... ... £10.45 Transistor UHF Tuners-£2.00, 500K -ohms V/C PRICES DO NOT INCLUDE VAT
Elac 5" 3 ohm .. ... £1.75 with Switch -20p. 50 mIxed Tuner Valves-E2.25.
Elac7"x4"3 or ohm ... £1.52 Brand New Transistors BF115, BF173, BC171, Tel: 72776/75517 STD CODE 037-23
BC153, BC135, BC113, BC117, 80115, BA102,
Elac 8" x 5" 3, 8or 15 ohm ... E1.93
BA129. All 10p each.
Wharfedale Bronze 8 RS/DD [3.11
All prises Include V.A.T. CONSTRUCTION AIDS-Screws, nuts,
Wharfedale Super 8 RS/DD £5-50 p. & p.10p per order
Wharfedale Super 10 RS/DD £9.80 Money back guarantee. S.A.E. for leaflets. spacers etc., in small quantities. Alu-
minium panels punched to spec. or
Goodmans 8P 8 or 15 ohm £3-80
ELECTRONIC MAILORDER plain sheet supplied. Fascia panels
Goodman: 10P 8 or 15 ohm ... £4.49
etched aluminium to individual re-
Goodmans 12P 8 or 15 ohm £11.55 (BURY) LTD. quirements. Printed circuit boards-
Goodmans I5P 8 or 15 ohm .. £17.05
62 Bridge St., Ramsbottom, Bury, masters, negatives and boards, one-off
Goodmans I8P 8 or 15 ohm .. £29.70
Lancs. Tel. Rams 3036 or small numbers. Send 6p for list.
Goodmans Twinaxiom 8 ... ... £6.79
... Ramer Constructor Services, 29 Shel-
Goodmans Twinaxiom 10 E7.61
boume Rd., Stratford on Avon,
Goodmans Axent 100 £6.60
Warwks.
Eagle DT33 dome tweeter 8 ohm E4.95
Eagle HTI5 tweeter 8 ohm ... £3.46
CTS tweeter 8 ohm ... E1.21

FREE:
Eagle
Eagle MHTIO tweeter ... ... £3.30 LED's
Eagle CTIO tweeter ... LI -92 TIL302 4 for £10
Eagle Xovers CN23, 28, 216 LI -IO 6 for £14
Kef T27 £4.67 DL34 4 digits EIS
Kef TI £5.50 TIL360 6 digits £18
Kef BI10 ... £6-16 TIL209 4 for LI
Kef B200 ... L7.42 50 for £10
Kef BL39 ... ... ... £10.72 Equivilant may be supplied as stocks levels
Kef kit 2
Richard Allan 12" d cone 3 or
£247S FULLY dictate
'SPECIAL'
15 ohm .
£2.20 ILLUSTRATED Green/Red LED matched pair LI
Richard Allan 8" 3, 8 or 15 ohm £2-27 CALCULATORS
10"x6"3,8or IS ohm £1.92 CATALOGUE Advance Mini £45
8"x5"3or8 ohm :.. ... £1.38
AMAZING QUALITY Advance Exec. 8 £45
7"x4"3or8ohm ... ... L1-38 Advance Exec. 16-1 £95
3" 8 ohm or 80 ohm ... ... .65 Our superb catalogue is printed in easily Advance Exec. 16-2 £110
24" 64 ohm 6S read type. It has dozens of clear pictures Post & Packing I.C.'s. LED's, 10p. KITS,
Speaker matching transformer 3, and illustrations of thousands of the kinds CALC's, METERS 50p.
8or 15 ohm ... ... ... L1I0 of components you use. I.C.'s
Adastra Hiten 10" 10 watt 8 or MM531I Clock £12 50
£2 80 SPEEDY SERVICE ZN414 Radio £1. 10
Adastra Top 20 12" 25 watt 8 or Write now and we will be delighted Sig555 Mono/astab. £0.90
IS ohm .. ... .. ... L632 to forward a copy to you by return CA3082 7-seg. driv. £2 I O
Stephenspeaker. kits and ca.binets-send for of post. KITS (incl. I.C. sockets
illustrated brochure and list of recom- Calculator £41
mended speakers. PHONE ANY TIME Digitronic (6) £36
Car stereo speakers-ask for leaflet. You can phone for your free catalogue Digitronic (4) £32
PA/Disco amplifiers (carr. and ins. £1-00): whenever it suits you. Out of office hours Bywood clock kit £34
Baker 100 watt ... ... ... £46.00 leave your name and address on our ADD 10% VAT TO ALL ORDERS
Linear 30/40 £25 00 answering machine.
... ... £30 00
LATEST! New Digital Clock I.C.'s available
Linear 40/60 ... with alarms. S.A.E. for details. Complete
Linear 80/100 £50.00 £1 FREE kits with PCB & displays £24 00.
FREE with speaker orders over £7 "Hi-Fi When you receive your catalogue you
Loudspeaker Enclosures" book. will find out how you can obtain one
All units guaranteed new and perfect. pounds worth of goods absolutely free!
Prompt despatch.
Carriage and insurance 25p per speaker. PLUS
(Tweeters and Crossovers I5p each.) Free post and packing in U.K.
All prices quoted inclusive of V.A.T. Every item sold guaranteed brand new You may telephone your order and pay by
and marked by the manufacturer. ACCESS.
Phone 037 42 79033 or Write:- ANSAFONE-24-hour service.
WILMSLOW MAPLIN ELECTRONIC SUPPLIES
P.O. BOX No. 3

AUDIO, Dept. PW
Swan Works, Bank Square,
RAYLEIGH
ESSEX
SS6 8LR
E!WUJUDU ELECTRONICS
181 EBBERNS ROAD, HEMEL
Wilmslow, Cheshire, SK91HF HEMPSTEAD, HERTS. 0442 62757

286
 B.H. COMPONENT FACTORS LIMITED COMPARE OUR PRICES
SPECIAL RESISTOR KITS (1-W 5% or fW 5% CARBON FILM) Speaker Bargains Microphone Bargains
10E12 Kit: 10 of each E 12 value, 10 ohms-1M, a total of 610, £3-10 net E.M.I. 13 x 8 In 3, 8615 OHMS MIC45 "ACOS" metal case,
25E12 Kit: 25 of each E12 value, 10 ohms -IM,
total of 1,525, £7.20 net
a PLAIN crystal hand .. .. 95
POLYESTER CAPACITORS MULLARD C280 250V WITH TWEETER .. £2.25
. CM 20 Crystal Hand .. 45
µF: 0.01, 0015, 0-022, 0033, 0-047, 3fp each; 0068, 0-I, 0.15, 4fp each; Type 350-20 watt with Tweeter DX143 Dynamic, cassette-
0.22, 54p; 0.33, 8p; 0.47, 9p; 0.68, lip; 1.0, I5p; 1.5, 22p; 2.2, Up. 8. OHM p. & p. 37p .. £7.25 type stick .. £1.10
MULLARD POLYESTER CAPACITORS C296 SERIES TWIN TWEETER .. £3 -SO CM70 PLANET stick metal,
160V: (µF) 0.01, 0015, 0-022, 24p; 0-047, 0-068, 3fp; 0.1, 0.15, 44p; 8x 51n 3, 8&
OHMS ..
15 £1.10 switch crystal £1.45
0.22, Sp; 0.33, 6p; 0.47, 74p; 0.68, 1Ip; 1-0, 124-p. 7 x 4 in3&8
OHMS -90 DM160 Dynamic uni-dlr, ball
400V: (µF) 0-001, 0-0015, 0-0022, 00033, 0.011, 2fp; 0-015, 0-033, 34p; FANE8"8. OHM DUAL CONE £2.10 metal 7S
0-068, 4fp. CELESTION 8" 15.OHM £1.40 UD13 OHM unl-dir,
BAKER GROUP 25 12" 25 ball metal £.4SO
MINIATURE ELECTROLYTIC MULLARD C426 SERIES (6p each) WATT 8 or 15.OHM .. ES -75 TW209 LESSON DUAL IMP
.

(pF/V) 1/63, 4/40, 8/40, 10/40, 10/64, 16/40, 20/64, 25/25, 32/10, 40/16, 64/10, 21"8 or 64 OHM p. & p. 10p. 45 ball metal, uni -dir. ES75
80/16, 80/25, 100/6-4, 125/16, 200/6-4, 200/10, 320/6-4, 125110. POSTAGE 25p per SPEAKER CONDENSER MIKE uni; dir.
MULLARD C437: (µF/V) 64/64, lop; 160/25, lop; 160/40, 12p; 640/6-4, Kit -Form Cabinets Teak £7.9S
lop; 1600/6-4, 16p. GUITAR MIKE .. 45
(17" x 10" x 8") with a 13' x 8'
ELECTROLYTIC CAPACITORS. Tubular and large can or8" CUT OUT £2.75 LAPEL TYPE, crystal .. .N
(µF/V) 2-5/50, 3p; 4/10, 10/25, 16/15, 20/25, 25/15, 25/25, 40/6. 64/10, 200/6, 18x11 x 9 with 13"x8"cutout POSTAGE 17p each.
250/10, 5p; 10/6, 10/50, 25/50, 32/50, 50/10, 64/25, 100/25, 6p; 50/50, 64/40, for EMI 350 £3.70
250/15,1,000/3, 7p; 100/50, 250/25, 400/10, 500/10 500/12, 640/ 10, 1,000/6, 9p; (12"x12"x6") with a 8"x5"or Battery Eliminators
500/25, lip; 500/50, 14p; 1,000/12, 11p; 1,000/25, 2,000/12, 2,500/12, 17p; 8" CUT OUT.. £2.25 240v input 6 or 9v d.c. output
1,000/50, 39p; 2,000/25, 17p; 2,500/25, 33p; 2,500/50, 62p 3,000/50, 72p; (PLEASE SPECIFY CUT OUT) at 150mA £1.00
5,000/50, 94p; 1,000/100, 66p; 8/350, 14p; 16/350, 19p; 32/350, 25p. Add 35p per Cabinet for p. 6 p. 240v Input 6, 74 or 9v output
MINIATURE CERAMIC PLATE CAPACITORS Cartridges with standard fittings 6 at 300 mA £2.90
50V: (pF) 22, 27, 33, 39, 47, 56, 68, 82, 100, 120, 150, 180, 220, 270, 330, 390, 12v d.c. input (for cars, fits in
470, 560, 680, 820, IK, K5, 2K2, 3K3, 4K7, 6K8. (6F) 0.01, 0.015.0.022, 0.033, styli
1
GOLDRING G850 .. .. £280 lighter socket) 8, 74 or 9v
0047, 2fp; 0- I, 30V, 44p; 0- I, IOOV, 54-p.
CARBON FILM RESISTORS 4W 5 %. 10 ohms-2-2M, 4W 5 %, 10 ohms - GOLDRING G800
ACOS GP91/2SC or GP91/
£4.40 d.c. output at 300 mA
P. & P. 10p
.. £2-S0
IM, Ip each or for 62p;
100 000 for £4.50.
METAL FILM RESISTORS IW 5% 10 ohms-I0M,
for £110."15E12 KIT (15 each valve 100-1M) £8"
le each or 100
3SC STEREO COMPAT-
IBLE
ACOS GP94 STEREO CER.
90
£1-S0
Tapes - "MYLAR" base finest
quality British made.
Veroboard 011 0.15 IN4001 671 QUANTITY DISCOUNT ACOS GP95 STEREO CRYS. £t-15 5" 600 tt 31p 5)" 1800 tt Alp
2- x 5in 29p 28p IN4002 74p SPECIAL BULK BUY PRICES ACOS GP96 STEREO CER. £1.50 5" 900 ft 45p 7" 1200 it 559
2- x 31in 26p 19p IN4003 9p ARE AVAILABLE BY 9THAC SONOTONE STEREO 5" 1200 ft Np 7" 1800 ft top
34. x 5in 32p 33p IN4004 9fp QUOTATION FOR LARGE CERAMIC(DIAMOND) .. £1.70 55" 900 ft 411p 7" 2400 ft !Sp
3 - x 3}in 28p 28p IN914 79' AND TRADE. 9THAC/G SONOTONE 58" 1200 ft 55p
2- x Iin
2 - x 5in (plain) --
7p 7p
14p
µL914
OC71
35p
13p
_PROJECTS

S.C.R.
STEREO CER. (DIAMOND)
SLIMLINE £1.70
POSTAGE 9p each.

- IA .

2 x 31in (plain) 12p OC75 17P 50V 29P 3A 33p ACOS GP67/2C MONO CRYS. -65 PLASTIC LIBRARY CASES
5 x 31 -in (plain) 22p OC83 10D 100V IA 33p 3A 40p ACOS GP101 COMP. CRYS. -85 for 5in Reels 16p
Insertion cool 59p 59p 400V IA SOp 3A 60p 19 -TI SONOTONE STEREO 51ín Reels 19p
T ack cutter
P ns, pkt. 25
44p
10p
44p
IOp
Screened wire, m
Twin screened wire, in
3f
lop
CRYSTAL ..
POSTAGE 5p per CARTRIDGE
-00 lin Reels 21p
P. & P. 5p each
Stereo s.c. wire, m IOp
2 pin DIN Plug, 12p; Skt., Connecting Wire, all colours 24p THIS MONTH'S SPECIAL OFFER
10p, 3 pin DIN Plug, 13P; Neon bulb 90V wire ended 5 for 24p
Skt., 10 p. 5 pin DIN Plug, Preset skeleton pots 1K -IM 6p PLINTH to suit GARRARD 2025, SP25, etc. Teak finish complete with
180°, 15p; Skt., 12p. Tran- perspex cover. Our price £320. P. 6 P. 50p.
sistor Equiv. Book, 409. ALL PRICES INCLUDE V.A.T.
Carbon pots 5K -2M log, & C.W.O. only. P. & P. 10p on orders below (5.
lin, single 164p, single Discount: E10-10%, (20-15%. SEND 25p FOR COMPLETE CATALOGUE Add10% VAT on prices, inc. P. & P.
with switch 26p, dual 46p. Export Order enquiries welcome (VAT free)
Dept. P.W. 61, CHEDDINGTON ROAD, PITSTONE RIVERSDALE ELECTRONICS
Near LEIGHTON BUZZARD, BEDS. LU7 9AQ Mail Order Department W7/73, P.O. Box 470, Manchester M60 4BU
Tel.: Cheddington 668446 STD. (0296) GIRO No. 331 7056 ALL OUR MERCHANDISE IS FULLY GUARANTEED
Inquiries-S.A.E. Catalogue FREE. Callers please phone first.

Felstead Electronics 272 H.D.I. ... ... ... ... 283

INDEX TO ADVERTISERS Fi -Comp Electronics 268 Radio Component Specialise ... ... 211
Antex Ltd.... 205 Radio Book Services ... ... ... 282
Astro Electronics 276 Galleon Tradins, ... 283 Radio Exchange Co. Ltd. 267
Gladstone Radio 278 Radio & T.V. Components (Acton) Ltd 208,209
B. H. Components Factors Ltd.... 287 Greenweld Electronics 284 Radio Society of Great Britain ... 276
Baines. R. ... ... ... 282 ... Readers Radio ... ... ... 198
Baker Loudspeakers Ltd. ... 212 ._ HAC Shortwave Products 232 Red hawk Sales ... ... ... ... 283
Bedford Electronics ... ... 285 ... Harverson Surplus Co. Ltd. 255 Riversdale Electronics ... ... ... 287
:
Bells elevision ... ...
Bentley Acoustic Corporation Ltd.
... 282 Heath (Gloucester) Ltd. 196 RSC (Hi-Fi Centres) Lcd.
R.S.T. Valve Mail Order Co.
194,
...
195
268
... 204 Henry's Radio Ltd. 207, Coy. iv
Bernard, Gerald, ... ... ... 285 Home Radio (Components) Ltd. ... 263
B.I.E.T. ... 268 Cov iii
Bi -Pak Semiconductors 273, 274, 275 S.C.S. Components ... ... 196
253 S. & W. Electronics ... ... ... 285
Bi -Pre -Pak Ltd. ... ... ... 259, 276 I.L.P. (Electronics) Ltd. 231
Boffin Projects ... ... ... ... 285 Salop Electronics ... ... ... 285
Imhofs ... ... ... 210 Saxon Entertainment ... ... ... 227
British National Radio & Electronic Ivoryet Ltd. ... 264
School ... Coy ii, 228 Smicon Index Ltd. ... ... ... 282
Broadway Electronics ... ... ... 276 Sinclair Radionics Ltd. ... ... 280, 281
Bull, I. (Electrical) Ltd. ... JefElectronics .. 284 Shopertunities Ltd. ... ... ... 197
... ... 279 Johns(Radio) Ltd.
Bush & Meissner 256 Smith, G. W. & Co. Ltd. 200, 201, 202, 203
.. 204 Johnson (Radio) ...
Butterworth & Co. (Pub.) Ltd. 284 Surpleccronics ... ... ... ... 268
256
Bywood Electronics 286 Swanley Electronics ... ... ... 256
K.V.A. Electronics 204
206 Kensington Supplies 282
Caranna, C. ... ... ... ... 282 Keytronics ... 256 Tate Audio Transmission Equipment Ltd. 199
Chiltmead Ltd. ... ... ... ... 212 Teleradio Co. Ltd. ... ... ... 284
Chromasonic Electronics ... ... 213 Lasky's Radio Ltd.... ... ... 252 Texas Instrumenta ... ... ... 198
Codar ... ... ... 212 Lewis Radio ... 228 Thacker, A. H. & Sons Ltd. ... ... 210
Colomor Electronics Ltd. ... ... 278 Linear Products Ltd. ... ... ... 277 Trade Aids ... ... ... ... 232
Comet High Fidelity Discount London Computer Operators Training Trade Disposals ... ... ... ... 285
Warehouses ... 214, 215 Centre ... ... ... ... - 282 Trampus Electronix ... ... 284
Control Data Institute ... ... 272 Trannies ... ... ... ... ... 271
Maplin Electronic Supplies 286 Tuac Ltd. ... ... ... ... 252
D.E.W. Ltd. ... ... 285 Marco Ltd. ... ... 283
Dabar Electronic Products 272 Milward, G. F. . ... 277
Davian Electronics ... ... 264 Minikuta Electronics ... 284 Web Europa ... ... ... ... 206
282 Multitore Solders Ltd. ... 206 West London Direct Supplies ... ... 204
Douglas Electronic Industries Ltd. 232 Weyrad (Electronics) Ltd. ... ... 263
Omnia Products ... ... 286 Wheel ... ... ... ... 212
Electrokit ... ... 232 Wilmslow Audio ... ... ... 198, 286
Electronic Design Associates ... ... 278 Padgetts Radio Store 252
Electronic Mail Order ...
.

... ... 286 Partridge Electronics Ltd. 264

Electrospares ... ... ... ... 206 Pembridge College ... York Electronics ... ... 210
210
Electrovalue ... ... ... ... 251 Phonoson ics ... 264
Elekon Enterprises ... ... ... 285 Phocain Controls ... 286
Elvins Electronic Musical Instruments ... 228 Plymouth Polytechnic ... 283 Z & I Aero Services ... 288

287
 Head Office and Warehouse Z & I A E R O SERVICES LTD. Retail Shoo
85 TOTTENHAM COURT ROAD
44A WESTBOURNE GROVE Please send all correspondence and Mail -Orders to Head Office WI
LONDON
LONDON W2 5SF When sending cash with order, please include 12}np in C for postage and handling
Tel: 580 8103
Tel: 727 56411213 MINIMUM CHARGE ISnp. No C.O.D. orders accepted Open all day Saturday
Please note that the valves offered below are not necessarily of U.K. origin

6A870 0.86 61,13 0.60 1001 0.86 EF96 0.40 0Z34 0.60 PF818 LOO 11301 0.0
0A2 0.40
OA% 0.48 OATS 0.38 6F14 0.70 1002
10F1
0.65
0.75
First Quality Pull y Guaranteed EF97
EF98
0.65
0.75
EABC800.66
08190 0.60
PFL2000.65
P1.33 0.40
U403 0.70
U404 0.70
0132 0.40 6AU6 0.80 61,16 0.66
OB3 0.70
0.40
SANS 0.40 6F18
6/,28
0.50
0.80
10F9
10F1ß
0.66
0.60
, / EF183
EF184
0.80
0.35
KT86 B.35
KT7788 1.0
PL36
PI.82
0.66
0.40
U801 0.60
16ÁßC80
6BÁ6 0.66
OD3 0,40 6BÁ6 0.88 SF24 0.80 101.1 0.0 1 EF804 1.86 KT88 886
l'0 P1.82 0.46 0.40
1B3GT o 46
134 8;22
613E6
6ßF6 0.66
0.Sß 61,26
61,28
1.00
0.86
101.1311 0.70
12A/3 0.75
`/V BRAND
EKO
EL94
0.82
0.50
1(78
NÁB0800.40
1'1.83 0.45
P1Á4 0.40
UAF41 0.70
UAF42 0.0
E1.36 0.50 PC86 0.60 P1.302 0.95 Uß41 e65
lß4 0.0 urns 0.76 6I28 0.70 12Áßb 0.70
EL41 0.75 PC88 0.60 PI.004 0.75 UBC41 0.66
136 613J6 0.66 601(6 0.60 12ÁC6 0.60
0.46
6BK7A 0.76 6J4 0.60 1917E6 0.80 EL81 0.0 PC99 0.60 F1.508 0.90 UBC8I 0.45

ELECTRONIC VALVES
184 0.80 EMS 0.50 P097 0.60 PL609 1.10 UBF80 0.40
186 0.80 68376 0.48 6J6GT 0.40 12AL6 0.56 UBF89 0.40
6J6 0.80 124Q6 0.50 EL84 0.86 PC900 0.48 PI.801 1.00
1T4 0.80 811516 0.60 1.1.86 0.43 PCC84 0.40 F1.802 0.96 (1 811 0.70
1Ú4 0.40 63Q6 0.85 6J7 0.45 12AT6 0.40 0.40 081.21 0.70
01(477 0.00 12AT7 0.40 30017 1.10 90AÚ 2.40 0Y80 0.86 EC088 0.40 1.1.80 0.40 P0085 PM84 0.60
1116 0.76 6BR8 0.76 DY87 0.86 1(0089 0.50 EL90 0A2 POCOS 0.56 PY31 0.86 UC92 0.46
6K8GT 0.75 12AU6 0.45 30018 0.90 90AV 3.50
1V2 0.0 6087 1.36
6)(7 0.48 12A137 0.33 30F0 1.00 9001 0.76 DY802 0.37 EC091 0.30 EL360 1.15 PCC89 0.56 PY33 0.63 Ú0086 0.43
1X2B 0.56 6BW6 0.80
E8OF 1.85 E001890.65 EL822 1.50 F00189 0.60 PY80 0.40 UCF80 0.70
6BW7 0.90 0K80 0.46 12AV6 0.45 SOFL1 0.80 90CV 2.40
9021 0.40
30FL12 1.10 807 0.60 E88CC 0.70 E008071.00 ELL80 0.86 F00ß010.96 PY81 9.30 UCH21 0.60
334 0.46 6139(6 0.85 6K26 0.76 12AV7 0.70
BLBOT 0.66 12AX7 0.88 30FL14 0.90 813 4.00 1(180F 1.00 ECF80 0.85 EM71 0.80 PC0806 0.95 PY89 036 UCH49 0.70
11A6 0.75 6BZ6 0.45 8.90 ECF82 0.36 EM80 0.46 PCFBO 0.00 PY83 0.38 UCH81 0.40
0.40 604 0.56 61.7 0.46 12AY7 0.76 301.1 0.40 886A 0.85 E810F
384
6030T 0.66 61.18 0.60 12B4A 0.66 301.16 0.96 6642 0.70 EAB080.38 ECF3041.66 E8(83 0.0 PCF82 0.86 PY88 0.40 Ú0181 0.80
3V4 0.70
61.1)20 0.60 12BA6 0.46 001.17 0.96 6080 1.76 EA149 0.60 ECH43 0.76 E9184 0.35 PCF84 0.80 PY600 1.00 (0189 0.36
11140Y 0.75 6086 0.40 6148 1.00 EBC33 0.60 ECH81 0.80 E8(83 1.00 PCF86 0.60 PY800 0.47 U0L83 0.05
0(140 0,40 6CD6GA 65770T 0.56 19BA7 0.60 301'12 1.00 UF9
6P28 0.86 1211E6 0.50 30F19 0.95 0146B 2.60 &B041 0.86 ECH83 0.46 113687 0.70 PCF87 110 PY801 0.50 0.06
0V40 0.0 1.30
13807 0.0 30P1.1 0.95 6380 1.26 EBC81 0.88 ECH84 0.45 EN91 0.40 PCF8010.0 PZOO 0.88 UF11 0.0
6Y80T 0.46 0007 0.60 6Q7 0.60 P0F8020.0 QQVO2-8 1JF41 0.85
68.87 0.46 1913Y7 0.86 301'1131.10 4939 2.25 EBF80 0.40 1(0180 0.50 EY61 0.40
8Z3 0.76 OCHE 0.60 &B183 0.40 E0181 0.60 EY80 0.75 P0F8050.0 6.26 UF42 0.66
0240 0.45 601.6 0.0 6807 0.46 12E1 S.00 30PL14 1.25 7199 0.85
EBF89 0.32 ECL82 0.36 EY81 0.40 PCF8060.75 QQV03-10 11F42 0.95
6/30L2 0.90 60(16 0'80 60K7 0.0 12K5 1.00 35A3 0.60 7186 1.50
1.0 E131.31 1.0 ECL83 0.70 EY83 0.66 PCF808 0.90 1.25 1/F80 0.56
6A B4 0.46 00W4 0.70 651.7610.46 12K70T0.0 35175 0.76 7896
63F4A 0.60 6CY6 0.60 68N7GT0.46 12Q7GT0.45 3686 0.06 A2293 E20 E003 0.0 ECL84 0.55 EY80 0.40 PC162000.70 TT21 3.80 UF86 0.40
0.0 EC80 E01.83 0.56 EY87 0.43 PC1.81 0.50 TT22 4.00 111,89 0.40
6305 0.25 8CY7 0.75 68Q7 0.0 128117 0.50 3006 AZ1 0.00 8.655
066
0.0 3606 0.76 AZ31 0.0 E086 0.0 E01.80 0.40 EY88 0.43 P01.82 0.85 U18/20 0.76 Ú1.41

0.50U97
0.807 0.45 803 0.56 68117 0.50 20131
1126 0.85 U1.84 0.48
6A116 0.60 61106 0.80 6T8 0.88 201.1 1.10 361.60TO.76 CBLI 0.90 1(088 0.60 1(011.800 EZ40 0.60 P01.83 0.05
CBL31 1.00 0.66 2'20 U28 0.86 Ú8(84 0.80
4ÁJ8 0.80
OAKS 0.40
SAXO 0.60
CALS 053
60K8 0.60
ODQ6B 0.76
61384 1.26
6EA8 0.65
6U4GT 0.70
OÚ60 0.76
6118A 0.48
6260T 0.45
20F1
20P4
20P6
2606
0.60
1.10
1.20
0.60
36W4 0.40
8028 0.76
3624) 0.40
31Z60T0.70
CY1
CY31
DAM 0.0
DF96 0.0
0.0EF40
0.0 1(090
&
0.45
E093 0.60
E0036 1.00
EF37A 1.00
EF41
1(949
0.66
0.70
EZ41
EZ80
EZ81
0.76
0.28
0.29
GT1O 8.00
P0184 0.46
PCL86 0.45
P01.88 1.26
P012000.75
1131

1162
U76
0.70
6.60
0.40
0.40
UY1N 0.0
UYII 1.00
ÚY41 0.48
UY82 0.50
6A1.5 0.22 8E117 0.80 6X4 0.40 201.00T 0.0 501.6 0.80
EF80 078 U 68 0.48
6E37 0.85 6X60T 0.46 26240 0.85 SOBS 0.70 DK92 0.70 E0040 0.70 0.50 0Y001 0.70 P01.801.10 0.40
W739 0.76
6AM6 0.87
6EW6 0.70 6X8 0.66 25Z6GT0.76 6006 0.60 0196 0.0 E0081 0.40 EF86 0.85 (1Z30 0.45 ?01.8010.96 (1391 0.76
0.0
6AQ6 0.42
6F1 0.76 BYO) 0.80 30A1 0.60 60CD6G1.20 DIM 0.55 EC(.8, 9 00 EF86 0.0 Gm 0.40 1'01.8060.50 11201 0.60
X013
6AQ6 0.70 0OAE3 0.40 60E86 0.66 DX70 0.0 Y63 0.76
OARS 0.66 6F6 0.76 7Y4 0.76 ECC89 0.85 OZ92 0.0 F0ß0 1.50 11281 0.65 Z7199 8.0
9BW0 0.70 3001 0.80 60L6GT0.60 1)36160 0.68 EF91 98
0.9RIM

6Á1(8 0.66 61,00 0.45 0Y01 E0084 0.30 EF99 0.36 GZ33 0.75 PF80 0.70 U282 0.55 Z8030 1.35
11186 0.0 6F11 0.0 1002 0.0 30010 1.00 81.82 0.55 0.56

TRANSISTORS
AC128 0.18
BD121 0.65
-
21(696 0.16 B0123 0.80
288º8 0.80 AC139 0ß8 BD1 0.76
28898
28706 0.80 .80163 0.20 B1ß131 0. - .(.,a
216706
21(706
2/4708
0.70
0.10
0.16
A0164
20167
AC169
0.16
0.17
0.10
B001ß9
BB116
BF167
0.80
0.2020
0.18
`.s
28763 0.25 A01711 0.17 BF173 0.80
280828 0.0 Á0187 0.25
0.26
BF179 0.30
21(830 0.20 .80188 BF180 0.50
28997 0.50 A0Y17 0.26 BF181 0.80 8
281131 0.22
0.26
ACT'S
ACY19
420
0.26
BF1174
BF186
0.20
6.20
.r..
2/61132
28I104 1.26 ACY20 0.20 BF184 0.14 F
2511909
9571303
2511304
0.17
0.17
0.80
ACY21
A0Y22
AD140
0.20
0.10
0.0
BF196
BF106
BF197
0.14
0.12
0.12
r i.
a ' G. ,
.11
11

II
3

2161306 0.80 AD149 0.46 BF90 0.86

21(1306 0.26 A13181 0.35 BFW87 0.26
281307 0.86 A11162 0.86 BFW88 0.20
281000 0.26 ADZ11 1.85 BFW89 0.20
1.85
2161613 0.17 AF114
AF116 0.17
ááááé ó2O0 MULTIMETERS MADE IN USSR
0.80 BFY17 0.40
2571711
281766 0.76 APIA 0.17 BFY18 0.85 Prices of these exceptionally well made instruments range
283147
2N221
0.76
0.60
AF117 0.17 BFY60 0.80 from £4.95 to £10.50. Please write for Illustrated catalogue.
2/629187 0.25 AF125 0.80 BFY69 0.20
283919 0.20 AF127 0.20 B8Y26 0.17 Serlas 821(611 -watt 2R3&ß Diodes
2512968
ºN2477Á
0.20
0.16
AFI 80
AF181
0.86
0.85
B8Y27
B8Y28
0.15
0.17
SYNCH ROS COPE TYPE C1-5 Available In: 7.6.82.11-12-16.24.27.30.33.36.83-68
volte. 5020 each.
2519047 0.40 AFI86 0.40 B8Y66 0.20
9579900 0.95 AFAFZ11 0.80 0.12
0 '/ DIODES
º512923
21(2924
28 9994
983026
283063
0.95
0.12
0.15
0.10
0.20
Áp219
A8Y24
A8Y27
A8Y28
0.45
1.00
0.36
0.0
04 6
0016SÁ
0022
0023
0024
0026
0.
0.60
0.60
0.60
0.86
". . -
blade InU88R
0Aß
0A0
O A7
0Aß0
025
012
0.16
0.20
0A81
0Á86
GÁ88
OA90
007
0.07
816
007
21(3064 0.60 AOY29 0.20 0024 Oß6 008 0A91 007
2169066 0.0 A0Y64 0.25 oral) Leo
0.60 0A7Ú 008
07 0A90 0'07
2N3184 0.26 Á8Z36
.88216
0.70
0.70
0086 0.60 -
OÁ79 007 0420 007
283184 0.26 0036 0.46
283391 A8217 0.76 0042 0.20
2573099
0.17
0.17 A8Z18 0.76 0044 0.19 MINIATURE SILICON HALF-WAVE
21(3393 0.15 AB220 0.96 0046 0.12 WIRE -ENDED RECTIFIERS

0.16. j
283894 0.16 Á8291 0.40 007 0.10 007
251 8386 0.80 Á(1Y10
BC107
0
0.10
0071 0.12 - , I84002
151404
100 p.i.p.1.v.,
400
lA
lA 008
º26 3409 0.16 00739 0.12 012
80108 0.10 0073 0.80 Iß400 800 D-lv. IA
2573403
289404
216344
0.16
0.88
0.20
80109
BC119
0.10
0.10
13076
0078 0.16 --
i 186399
íN6408
]00
1000 p.1.v.
460 pl.v.
31.v. 1.6A
9.OA
11A
086
00
816
283416 0.16 80118 0.20 0078 0.26 BY101
130134 0.20 0078D 0.20 BY106 800 p.l.v. 11A 036
2/69417 0.25 BY127 1260 p.l.v. IA 0.18
2703 0.10 BC147
BC149
0.10 0081 0.20 3 -Intube Otted with telescopic viewing hood, giving DD000 60 p.l.v. 500mA 016
28383704 0.10 0.10 00930 0.20 bright display in full daylight. Sensitivity 10mV/mm 0D06 400 pax. 60mA 025
288707 0.12 BC102 0.12 0093 0.20 (narrow band) to 8OmV/mm (wide band). 085
2N3700 0.12 BC1 0.16 00140 0.86 00068 800 Dl.v. 500mA
0.20 00140 Bandwidth 10 c/6-10 me/e. Triggered sweep pre-set
283710 0.10 BC1O8 0.80 at µsec per troke.
º083719 0.10 BÚ176
BC386
0.20
0.26
00170
00170
0.25 Free -running time base 20 c/e to 200kc!e with bullt-in VALUE ADDED TAX
0ßO calibrator providing timing marks at 06-.2-1.5.
0.26Free-runnFree-runningcrystal

0.16CONTAIN
2N9900 0.25 BCY80 0.26 001712N390º 0.86 20-100 µ nee. THE ABOVE PRICES DO NOT INCLUDE V.A.T. WHEN
28709 0.60 BCY81 0.80 0020 0.0 ...mumble calibrator directly calibrated in volts. REMITTING CASH WITH ORDERS PLEASE ADD
28746 0.86 BCY38 0.26 OC2o1 0.80 Input attenuator 1.10.10. 10% OF THE VALUE OF GOODS INCLUDING POSTAGE
AC113 0.15 /301'14 0.80 power supplies 127/230v AC. AND ßÁ301.I1(0. AB SORE OF THE ITEM STILL
ÁC1116 0.30 BCY72 0C907 0.65 THE PROPORTION OF PURCHASE TAX,
AC126 0.60 B07..10 0.30 00703 440 PRICE 6300. Packing and carriage 61.00. RESPECTIVE AMOUNT WILL BE REFUNDED.
A0127 0.17 BCZII 0.40 00204 0.40

288
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expert. Complete the coupon (or write if you prefer not to cut the Metricatne Gane
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in the next few years, my earnings increased fourfold".-Student To B.I.E.T., Dept. BPW06 QN IBPW061
C.C.P., Bucks. Aldermaston Court, Reading RG7 4PF
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RHO OC'? FOR YOURSELF Block Capitals Please
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These letters - and there are many more on file at AIdermaston Court
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 YOUR COMPLETE AUDIO -ELECTRONIC STORES
More of everything at the right price. All your electronic requirements
within 200 yards- call and see for yourself.
ELECTRONIC KITS
BUILD 20 + 20 WATT INTEGRATED Henry's introduce new huge
range of audio and electronic
kits now in stock, everything
I.C. STEREO AMPLIFIER supplied, tremendous value.
Detailed list Ref. No. 14 on

*
TEXANTHE
FREE TEAK CABINET ;211:7-t7;
(As featured in "Practical Wireless"
May to August 1972)
request.

ZN414
circuit
IC RECEIVER
Radio integrated
as featured in Practical
FEATURES. New slim design with 6 - IC's, IC Wireless, January 1973.
Sockets, 10 silicon transistors, 4 rectifiers, 2 zeners.
Special Gardeners low field slim line transformer. Article Reprint Ref. No. 19
Fibre glass PC panel. Complete chassis work. IOp. Price [I .20.
HIGH QUALITY & STABILITY ARE PREDOMINATE FEATURES BATTERY TAPE DECK
-DEVELOPED BY TEXAS ENGINEERS FOR PERFORMANCE, Garrard 9 volt Tape Deck
RELIABILITY AND EASE OF CONSTRUCTION. with heads, etc. As previously
FACILITIES. On/off switch indicator, headphone socket, advertised. Limited quantity.
separate treble, bass, volume and balance controls, scratch and £9.50, post 30p.
rumble filters, mono/stereo switch, Input selector; Mag. P.0 LEARN A LANGUAGE
Radio Tuner, Aux. Can be altered for Mic., Tape, Tape -head, etc
(Parts list Ref. 20 on request). Recorded Cassettes with step
Constructional details Ref. No. 21 30p by step phrase books.
P.W. Tricolour French, German, Spanish
as per April/May Italian. £1.36 per course.
SPECIAL P& P 45 P list
June 1973. Parts * SLIM £5.00 per set of four.
KIT
PRICE 8.50 on request (52A).
COMPLETE WITH FREE TEAK CABINET
Designer approved kits distributed by Henrys!
DESIGN WITH
SILVER TRIM
Overall chassis size
14}"x6"x2"high
3
DISCO SPOTBANK
channel Disco
for use with any psychedelic
lighting display.
Spotbank

£1275, p. & p. 35p.

LOW COST HI-FI SPEAKERS TEST EQUIPMENT Just a selection! HI-FI EQUIPMENT
E.M.I. Size 13f" x 8}". Large Ceramic Magnet. SE250BPocket Pencil Signal Injector [1.90 Warehouse prices with
TYPE ISO 6 watt, 3, 8 or 15 SE500 Pocket Pencil Signal Tracer £1.30 BIG DISCOUNTS plus
ohms £220. Post 22p. THL33D Robust 2K/Volt £4.55 with case [4.95 demonstration (for call-
TYPE 150 TC Twin cone ver- TEI5 Grid Dip Meter 440 KHz-280 mHz [1745 ers) and GUARANTEES.
sion £2.75. Post 22p. 500 30 KIV Multimeter [9.25 FREE -24
With leather case [1050 page detailed
TYPE 450 10 watt with twin brochure (Ref. No. 17).
tweeters and crossover. 3, 8 2001-1 20KIV Multimeter £4.20. With case £4.95 You can see the savings!
or 15 ohms. L3.50. Post 25p. AFI05 50KIV Multimeter [8.50. With case £950
TYPE 35020 watt with tweeter U4341 AC/DC Multimeter with transistor tester with steel
and crossover. 8 and 15 ohms. case LIO'SO HIGH QUALITY
TE2OD RF Generator 120KHz-500MHz £1650. Carr. 35p CASSETTES
[7.50: Post 28p. TE22D The best UK low noise tapes
POLISHED CABINETS 150, 150TC 450 [4 60. Post 30p. Audio Generator 20Hz-200KHz £1750. Carr. 35p but at a special price.
ASSEMBLED IN POLISHED CABINETS (8 ohms) CI -5 3' Pulse Scope IOHz-I0mHz £3900. Carr. 50p
SERIES 6 (Assembled 150 T/C) per pair £1650. Post 70p TE65 Valve Voltmeter 28 ranges £17.30. Carr. 40p 'Living Sound' cassettes meet
the highest international
SERIES 8 (Assembled 450) per pair £1895. Post 70p ALL NOMBREX MODELS.'N STOCK standard (IEC 94A). Fantastic
price savings.
ML -3 MW/LW
TUNER to BUILD
PA-Disco -Lighting
UK's Largest Range-Write
phone or call in. Details and
demonstrations on request. ZeiMMEZ
6.e,e
Gei5eF
C60
3
for for
1.00 1.80 2.80
6 10
for

Uses Mullard Module. Slow DJ30L 3 Channel sound to light unit, 3KW. £14 56
C90 1.33 2.57 4 20
motion tuning. Built in DJ4OL 3 channel Mic (built-in) to light., 3kW. £38.75
C120 1.62 3'15 5.00
battery. Ferrite aerial. Overall DJ70S 70 watt Disco amp/mixer. [4975 Full guarantee. Post paid ,

size 7" x 21" x 3f". TOTAL COST TO BUILD DISCOAMP 100 watt amp/mixer, £6885
£4.85, Post 15p. All parts sold separately. Leaflet No. 6 DJ1055 30 watt Disco amp/mixer, £32.25 Made by EMI especially for
Anti-Feedback Quality Mic., C1 .SO 1
Henry's.
"BANDSPREAD" PORTABLE TO BUILD DJ500 50 watt PA Amplifier £43.95
D1700 70 watt [5275 ULTRASONIC
Printed circuit all transistor design DJI000 100 watt £63.00 TRANSDUCERS
Mullard RF/IF Module. Medium
usingLong Wave bands plus Medium
and FIBRE OPTICS LIGHTING. -
GROUP 300 150 watt rms "Group" Valve Amplifier £8600
MICS. EFFECTS. PROJECTORS.
Operate at 40kcls up to 100
yds. Ideal remote switching
Wave Bandspread for extra selectivity.
Also slow motion geared tuning, 600
mW push-pull output, fibre glass PVC
Everything for PA Disco -
FREE Stock List Ref. No. 18
Lighting. -
SPOTS. DIMMERS -STANDS. MIXERS. SPEAKERS. and signalling. Complete with
data and new I.C. circuits.
£5.90 per pair. Post 'Opt
covered cabinet, car aerial. Attractive PORTABLE DISCOS -DETAILS ON REQUEST
appearance and performance. CREDIT TERMS FOR CALLERS MARRIOT TAPE HEADS
TOTAL COST TO BUILD L7.98 4 TRACK MONO or
p.P 32o. (Battery 22p). BUILD THIS VHF FM TUNER 2 TRACK STEREO
5 TRANSISTORS 300 kc)s BAND- '17' High Impedance £2.00
WIDTH, PRINTED CIRCUIT, HIGH '18' Med. Impedance [1.00
'36' Med.-Low Imp.
CATALOGUE FIDELITY REPRODUCTION. MONO
AND STEREO Erase Heads
£3.50
for above 73p
'63' 2 track mono-
Fully detailed and illus- A popular VHF FM Tuner for quality HiI.np. [1.75
trated
aspect of
plus data,
covering every
Electronics
circuits and
- and reception of mono and stereo.
There is no doubt about it -VHF FM
gives the REAL sound. All parts sold
separately. Free Leaflet No. 3 & 7.
'43' Erase Head for above 75p
7 SEG & NIXIE TUBES
information. 10,000 Stock (Post 15p per I to 6)
lines at Special Low Prices TOTAL £6.97, p.p. 20p. Mk. Decoder Kit £5.97.
I
XN3, XNI3, GN6 0-9 side
and Fully Guaranteed. Built IC Decoder £6.50. Tuning meter unit E1 -75. view with data, 85p.
Post Mains unit for Tuner and/or Decoder PS6/12 £3.25. Post 20p
GNP -7, GNP -8 0-9 side view
PRICE P Paid with decimal points and data,
(40p FOR CALLERS) SINCLAIR PROJECT 60 MODULES 95p.
PLUS! FIVE 10p -SAVE POUNDS! 3015F 7 seg £2 each. £7 per
4 with data.
[357;
VOUCHERS
Send to this address
HENRY'S RADIO LTD.
-
Z30
STEREO 60

PZ6
[7.97;
[6.37;
Z50
PZS
PZ8
[477
[3.97
[4.77 Il *it
PACKAGE DEALS
12 and 24 hour clock circuits
Ref, No. 31 15p.

Miniature Amplifier
Post 25p 5 transistor. 300mW o/p.
(Dept. PW) 3 ALBEMARLE Transformer for PZ8 £2.95 2xZ30, Stereo 60, PZ5 £15.95 Fitted volume and sensitivity
WAY, LONDON, E.C.I.- Active Filter Unit £4 45 2xZ30, Stereo 60, PZ6 £18.00 control, 9 volt operated.
for cataloge by post only. Stereo FM Tuner £16.95 2xZ50, Stereo 60, PZ8 [20.25 [1 75 each P/P 15p.
All other mail and callers IC12 £1.80; Q16's £15 pr. Transformer for PZ8 £2.95
to "303" see below. Post etc. 20p per item PROJECT 605 KIT £1995 Quality Slider Controls
60mm stroke singles and
All prices are exclusive of 10% VAT See earlier page of this magazine for ganged. Complete with knobs.
which must be added to all orders inc. 5K, 'OK, 25K, IOOK, 250K,
transistors, I.C.'s and Semi Conductor 500K. meg, Log and Lin. 40p
VAT carr/packing. (Note: Catalogue is not
subject to VAT).
prices-latest list Ref. no. 36 on request.
E. 4 O.E.
I

each, IOK, 25K, 50K, IOOK,

250K, Log and Lin ganged.
60p each.

Henry's LIMI O D
EDGWARE ROAD, W2
404-406 Electronic Components and Equipment01-4028381
354-356 High Fidelity and Tape Equipment 01-402 5854/4736
309 PA -Disco -Lighting High Power Sound 01-723 6963
303 Special offers and bargains store
All mail to 303 Edgware Road, London W2 1 BW
Open:- 9 am -6p
6 days a week
(309 closed
Thursday)
All stores open
al/ day Saturday