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40 COSMOS

IC PROJECTS

Continues In This Issue

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Stocking these 9 ECGT semiconductors

is like having hundreds of solid-state
deflection circuit devices on hand.
GTE Sylvania has checked
out hundreds of different TV
set models to find out what
they have in common.
And we've been able to
boil down practically all of
their deflection circuit needs
to just nine parts.
Then, we put together a
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But, we didn't stop at

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www.americanradiohistory.com

-Electronics
Radio
ELECTRONICS
MAGAZINE
FOR

THE

NEW

IDEAS IN

NOVEMBER 1974

More than 65 years of electronics publishing

COVER
FEATURE

BUILD ONE
OF THESE

42

First Computer Terminal You Build From A Kit

R -E Exclusive Report tells how the MITS computer
terminal operates and what it does -it's complete with
MODEM and cassette tape recorder jack.
by Thomas Durston

33

200 -Watt- Second Photoflash

Three different versions along with construction details
are described. by Jim Gupton

54

40 COSMOS

100

TEST
INSTRUMENTS

TELEVISION

HI-FI
STEREO

ON THE COVER
This complete computer ter ninal is
equipped to operate over phcne lines
and has an output you can con sect a
tape recorder to. Best of all, you
build it from a kit. Get all tho details
in the article starting on racle 42.

3 -Way IC Function Generator

One IC delivers sine, triangle and square waves.
by Robert Colman

Build

Digital Multimeters Under $300

R -E's technical editor brings you up -to -date on what's
available in the $300- and -under category and what they
will do for you. by Robert F. Scott

50

Digital Instruments For Electronics

There's more than DVM's that have gone digital.
service editor reports on "the rest." by Jack Darr

R -E's

$300?
DIGITAL MULTIMETERS UNDER
There's a heap of them. Here s a wrapup
showing what's available and what they
...:et page 45
wall do.

63

Equipment Report
Two Hewlett- Packard triggered -sweep oscilloscopes.

Hugo Gernsback (1884 -1967) founder

M. Harvey Gernsback
editor -in -chief and publisher
Larry Steckler, CET, editor
Robert F. Scott, W2PWG, CET,

69

Service Clinic
R -C networks and different waveforms. by Jack Darr

72

Reader Questions
R -E's service editor solves reader problems.

64

Step -By -Step Troubleshooting Charts

Waveform analysis and how to use it. by Stan Prentiss

26

Equipment Report
Technics model RS -676US Dolby cassette recorder.

technical editor
Arthur Kleiman, associate editor
Jack Darr, CET, service editor
I. Queen, editorial associate
Leonard Feldman
contributing high -fidelity editor
David Lachenbruch, contributing 3d tor
Barbara Schwartz, editorial assistant
Vincent P. Cicenia, production rat.nt.ger
Sarah Martin, production assistant
Harriet I. Matysko, circulation director
Arline R. Bailey, advertising coordinator
Advertising Sales Offices, see pa 1e 16

11

Circuits To Build
Part Ill presents another group of easy -to- build, yet
practical, IC projects. by R.M. Marston

45

61

GENERAL
ELECTRONICS

Vol. 43 'Jo.

The New FTC Audio Power Rules

How good are they? How big are the loopholes? You
get the answers here. by Len Feldman

Looking Ahead
Tomorrow's news today. by David Lachenbruch

24

Appliance Clinic
Automatic light switches. by Jack Darr

66

R -E's

Replacement Transistor Directory

This month's installment continues our coverage of
replacement transistors.
compiled by Elizabeth and Robert F. Scott

Cover photograph by Walter Herstati

Cover design by Louis G. Rubsamen

Radio-Electronics is indexed in ,Ipplied Science & Technology iede r

and Readers Guide to Periodinal
Literature.
re

//

'.A;
i..

Radio -Electronics, Published montly Dy Gemsback Publications, Inc., 200 Park A.'erue South,
New York City 10003. Phone: 212-7;7-4,400. Second -class postage paid at New Yo'k, N.Y. and
additional mailing offices. One -year sr. bscription
rate: U.S.A., U.S. possessions and O 3nuda, $8.75.
Pan -American countries, $10.25. Other countries,
$10.75. Single copies 75c. 1974 t
3ernsback
Publications, Inc. All rights rescued. Printed
in U.S.A.

Subscription Service: Mail all subscr pt on orders,

changes, correspondence and Postmaster Notices
of undelivered copies (Form 357E) to Radio Electronics Subscription Service, Bmilder, Colo.
80302.

DEPARTMENTS

116

Advertising Index

87

New Literature

108

Books

82

New Products

98

Next Month
Reader Service Card

16
6

Letters
New & Timely

119

stamped self- addressed envelop e must accompany all submitted manuscripts aid /or artwork or photographs if their return s desired
should they be rejected. We disc Oil any responsibility for the loss or damage o manuscripts
and /or artwork or photographs v hi e in our
possession or otherwise.
A

service to readers, Radio -Electronics publishes available plans or information relating to newsworthy products, techniques and szientific and
technological developments. Because of possible variances in the quality and condition of materials and workmanship used by readers, Radia-1 lectronics
disclaims any responsibility for the safe and proper functioning of reader-built projects based upon or from plans or information published in it is magazine.
As a

www.americanradiohistory.com

looking ahead
liquid -crystal quartz wristwatch at that price. Not only
are the traditional watch manufacturers in the race, but the
a

Flat TV screen
The long quest for a thin panel electroluminescent TV
screen as a substitute for the
cathode ray tube may be
nearly over, according to scientists at Japan's Sharp Corp.
They claim to have overcome
the drawbacks in previous
devices-short life and low
brightness. Lab samples of
Sharp's thin -film panels have

been operated for 10,000

hours "without any indication
of degradation" and with
brightness of more than 60
foot -lamberts at the regular
60- fields -per- second TV scanning rate. Contrast ratio was
given as better than 60 to 1.
Sharp's panel, said to be
about the thickness of a win-

dowpane, is

calculator manufacturers

such as Bowmar, Casio and

Eiko -are joining in, and before long the makers of IC's
are expected to enter the
market with their own brand
watches, just as they did in
the calculator field.
Calculators, meanwhile, are
glutting the market. With an
oversupply, the calculator industry underwent a severe
recession last summer and
was counting on the student
and Christmas markets to
help pull them out. Despite
inflation, prices continued to
drift downwards, with under$20 units no longer unusual
and an occasional bargain
showing up at less than $15.

three -layer

sandwich (electroluminescent
layer between two insulating
layers) and is driven at a peak
voltage of 260 volts ac. The
experimental unit is 48 x 36
mm (about 1.9 x 1.4 in.), has
81 picture elements vertically,
108 horizontally, and is addressed by horizontal and vertical grids. Sharp says production is now feasible and
the initial applications probably will be for calcuator and
computer display, rather than
TV. The device currently is
monochrome (orange- yellow),
but Sharp is working on a
three -color version. Sharp
officials are so confident
they're on the right track that
they predict the first no -tube
television set within "the next
few years."

Digital watches
The electronic digital watch
soon will be the hottest new
product on the market, and
there are indications that
prices will decline as rapidly
as those of electronic calculators. Until very recently, LED
and liquid -crystal types were
selling at $250 and up. During the summer, new models
came out in the $200 range,
followed shortly by watches
as cheap as $120. Next step:
$85. Timex is now marketing

Audio price probe

Is there illegal price- fixing
in the audio components busi-

ness? Spurred by complaints

from dealers, the Federal

Trade

Commission

brand -name manufacturers

and importers are withholding
merchandise illegally from
dealers who sell below specified minimum prices. The
FTC revealed no details of its
inquiry, but it's believed to
cover not only the traditional
audio retailers but mail -order
houses which advertise in
audio publications and various other discount operations, such as those in large
cities which quote discount
prices by telephone.

Solid -state sweeps TV

It probably won't come as
any surprise that solid -state
is

console finally has virtually

disappeared, dropping to only
2% of the total.

has

launched a nationwide investigation to determine whether

circuitry

83% of all consoles and

54.5% of all portables and
table models were solid- state,
but solid -state construction
accounted for only a little
more than 30% of monochrome sets.
Portables and table models
continued to increase their
share of the color TV market,
representing 71% of all sets
in the 1974 period, up from
66% in the first half of 1973.
The fastest growing picture
tube sizes were the new 13 -,
15- and 17 -inch categories,
at the expense of the 12 -inchand -under and the 25-inch
sizes. Remote control may be
coming into its own, accounting for a record 8.2% of
color sets in January -June
1974, up from 4.6% in the
same 1973 period.
In black- and -white, the 11and 12 -inch sizes represented
more than one half of the total supply for the first time (it
was less than 40% one year
earlier), and the monochrome

finally overtaking

the television industry. In the

first half of 1974, nearly 63%
of all color sets produced or
imported into the United
States were solid -state models, as compared to only
36.5% in the first half of 1973.
In the 1974 period, more than

Tighter UHF rules?

After 22 years of UHF
broadcasting, there is a strong
feeling among engineers on
the FCC staff that new measures are necessary to bring
a greater level of equality between UHF and VHF television stations. These could
take the form of new regulations aimed at better performance of UHF transmitters
or receivers or both. Recent
FCC tests of receivers indicate that the performance
level of UHF tuners has improved little, if at all, in two
decades. The Public Broadcasting System is beginning
a series of tests of both transmitters and receivers which
could result in recommendations to the FCC for further
action to mandate UHF -VHF
parity. The all- channel law
already resulted in bringing
the UHF receiver population
close to 100% of TV households. The more recent tuner parity rules make UHF as
simple to tune as VHF in cur-

www.americanradiohistory.com

-if

rent -model receivers

the
viewer can locate the UHF
signals at all.
Some sentiment is discernable at the FCC for an amendment to the all- channel law
to give the Commission the
authority to establish UHF

tuner performance standards.

The FCC currently has the
power to fix noise levels only
-and it's felt that congressional action would be required to give it greater
authority over other performance factors. So far there's
no groundswell for further action on UHF, but it could
build up in the coming
months.

$31.6 billion for electronics

The U.S. electronics industry brought in $31.6 billion in
factory sales last year, according to EIA. The biggest
segment was the communications and industrial market,
which accounted for $12.9
billion, followed by government electronics (military,
space, etc.) at $10.8 billion.
The consumer market accounted for sales of $6.9 billion, while replacement parts
represented $920 million in
sales. All segments of the
market registered increases
in 1973, and total electronics
business was up 7.4% from
$29.5 billion in 1973.

The other matrix

Although most of the publicity in the four -channel record
race has gone to the discrete
CD -4 (Quadradisc) and SQ
matrix systems, another matrix system is now making a
major bid. This is the QS system, being pushed by Sansui.
Sansui's catchword is VarioMatrix, which describes a new

four -chip decoder circuit that

has a three -position switch
for decoding QS discs, SQ
discs and synthesizing four channel from regular stereo
records.
by DAVID LACHENBRUCH
CONTRIBUTING EDITOR

STILL ONLY

ALL PARTS
INCLUDED

dyl

<

except tubes and transistors

YEAR GUARANTEE

A
PROVIDES YOU WITH A
COMPLETE SERVICE FOR
ALL YOUR TELEVISION
TUNER REQUIREMENTS.

Universal Replacement (In Canada $1.1 95)

This price buys you a complete -few
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ZIAN INC. for this purpose.
All shafts have a maximum length of
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Specify heater type parallel and se-ies
450mA or 600mA.

VHF Or UHF Any Type $9.95.

UHF /VHF Combo $15.00.
In this price all parts are

included.
Tubes, transistors, diodes, and nuvistors
are charged extra.
Fast efficient service at our conveniently located service centers. This price
does not cover mutilated tuners.
All tuners are cleaned ultrasonically,
repaired, realigned and air tested.

Customized tuners are available t a

cost of only $15.95. (In Canada $17.95 /$ I. 35)
Send in your original tuner for :Dmparison purposes to:

TUNER SERVICE CORPORATION

TSC

Backed by he largest tuner manufacturer in the U.S. -SARKES TARZIAN, Inc.

Tel IL 334 -0411
537 South Walnut St.
HEAIOUARTERS .BLOOMINGTON, INDIANA 4701,
Tel AG-791-9243
1528 S. 6th St. (P.O. Box 4534)
ARIZONA
TUCSON, ARIZONA 85713,
Tel: M-347-5728
1324 Marsten Road
BURLINGAME, CALIFORNIA 94010,
CALIFORNIA
Te
-521 -8051
123 Phoenix Ave.
CALIFORNIA
MODESTO, CALIFORNIA 95351,
T= 2t-69 -2720
10654 Magnolia Blvd.
..NORTH HOLLYWOOD, CALIF. 91691,
CALIFORNIA
8' 53 -0324
1111..T
505 Cypress St.
FLORIDA ..
.L .TAMPA, FLORIDA 33606,
4' 758 -2232
938 Gordon St.
GEORGIA .....ATLANTA, GEORGIA 30310,
91. 356 -6400
405 East Univ
ILLINOIS
CHAMPAIGN, ILLINOIS 61820,
L
31.
3' 2 ii '3- 5556 -7
ILLINOI
737 W. 55th St
CHICAGO, ILLINOIS 606
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1LLIN01

WATCH US
GROW

SKOKIE, ILLINOIS 60076,

INDIANA
INDIANAPOLIS, IND. 46204, .
INDIAN
_./.t_..HAMMOND, INDIANA 46323
KENTUCK
LOUISVILLE, KENTUCKY 4020&,
LOUISIANA
SHREVEPORT, LOUISIANA 7110
MARYLAND
BALTIMORE, MD. 21215,
MISSOURI
ST. LOUIS, MO. 63132,
NEVADA
LAS VEGAS, NEVADA 89102, ...
NEW JERSEY
JERSEY CITY, NEW JERSEY 07307,
NEW JERSEY ....TRENTON, NEW JERSEY 08638,
OHIO
CINCINNATI, OHIO 45216,
OHIO
CLEVELAND, OHIO 44109
OREGON
PORTLAND, OREGON 97210,
TENMESSEE
GREENVILLE, TENNESSEE 37743,
TENNESSEE
MEMPHIS, TENNESSEE 38111,
TEXAS
DALLAS, TEXAS 75218,
VIRGINIA
NORFOLK, VIRGINIA 23513
CANADA
TUNER SERVICE CO.. QUEBEC
CANADA
TUNER SERVICE CO.. ALBERTA

5..0

Brown $t. ..
112 West St. C1 r St.
11833 Grand Ave...
2920 Taylor Blvd
3025 Highland Ai
5505 Reisterstown d.
W.

10530 Page

Ave...

('

Western Av
547 -49 Tonnele Ave. r
901 N. Olden Ave. .
7450 Vine St.
Pearl Roas
1732 N.W. 25th Ave. ..
1215 Snapps Ferry Rd.
158 Barron Ave.
540 Garland Rd.
3295 Santos Street
Write headquarters office for address.
2

3 on

r: 675 -0230
^ 845 -2676

?'

845 -2676

31

634 -3334
861 -7745

l: 3:

358 -1186

3r

429 -0633

el:
Tel:
Tel:
Tel:
TeL
TeL
Tel:
Tel:
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7:

tTel:

el:
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384 -4235
792 -3730
6C'.393 -0999
2:

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56+

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741 -2314

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6- 4.639 -8451

9e -458 -2355
2-i 1 -327 -8413

8044552518 -9955

Write headquarters office for address.

Franchises available- Contact headquarters for information.

Circle

l:

reader service card

www.americanradiohistory.com

new Go timely
Active Citizens Bander is named
"Handicapped American of Year"
H. Keith Russell, Silver Spring, MD, a
member of the Montgomery County
REACT No. 2348, has been named Handicapped American of the Year by the
President's Committee on Employment
of the Handicapped, and was awarded
the President's Trophy, the nation's
highest honor to its handicapped citizens. (REACT -Radio Emergency Associated Radio Teams
an organization
of Citizens Band groups who keep a
24 -hour watch on CB channel 9, give
help to motorists in difficulties and assist in emergencies and catastrophes.)
Mr. Russell, who moves about with
crutches and long leg braces, works
continuously for handicapped people
especially in the area of removal of
architectural barriers- in addition to
his REACT volunteer work. In Montgomery County he was instrumental in
helping the passage of special parking
privileges for the handicapped, ramping
of shopping centers, curb -ramping ordi-

of the National
Angeles, is the
the 1974 Hugo
Award, a check
to a student in

Technical Schools, Los

most recent winner of
Gernsback Scholarship
for $125 given annually
each of eight leading

Radio waves may affect

human health

-is

H.

Duval W. Payne

electronics home -study schools. The

Award is in memory of the late Hugo
Gernsback, who devoted much of his
energy to encouraging young men in
the study of electronics.

Keith Russell

nances, and the removal of discriminatory employment practices.

He is also active in local and national
organizations concerned with the removal of such architectural barriers as
stairs, narrow doorways, etc., which prevent 10% of the population from moving
about freely.
Mr. Russell is chief of the Armed
Forces Institute of Pathology Histopath
Laboratory of Walter Reed Hospital and
has an additional part -time occupation
as a musician. He also builds musical
instruments and installs automobile
hand -controls for a large manufacturer.
In addition, he often travels to speak to
medical groups about the correct use of
medical aids for severely handicapped
patients.

Duval Payne and David Robinson

win latest Gernsback Award
Duval W. Payne, a home -study student

shop foreman for Daniels Chevrolet in

Colorado Springs, CO. He says: "The
knowledge gained (in my current Electronics course with NTS) has been of
extreme importance in the presently expanding use of electronics in cars. In
coming years,
think courses like this
should be included in expanded Auto
Mechanics courses."

David B. Robinson
A second prize -an RCA WV -529 -A
"Service Special" VOM- contributed by
RCA for the runner -up in each of the

1974 Award contests, goes to NTS student David B. Robinson.

Mr. Payne, who lives in Pittsburgh,
writes: "I am employed at present as
foreman of Building Equipment Maintenance for the U.S. Postal Service, which
has become so highly automated that
they have need for technicians.... The
things have learned are a tremendous
also
asset on my present job, and
intend doing part-time TV repair."
Mr. Robinson is an auto mechanic,
I

www.americanradiohistory.com

Radio waves may affect the nervous

system and behavior, and normal development and growth processes "at lower
levels than anticipated in the past," the
government Office of Telecommunications Policy stated in a report to Congress. The Office warns, however, that
the tentative findings are based on a
small number of experiments on a limited number of subjects, and that "casual relationships between the electromagnetic fields and observations are not
yet clearly established."
High concentrations of radio frequency
radiation is known to cause adverse
biological effects by generating heat in
the tissues. The thermal effects are
fairly well understood, and it has been
fairly well established that power densities of less than 10 mW per cm2 are
harmless to human beings, as far as
their heating effects are concerned.
Less is known of other effects of rf
radiation, though they have been suspected to exist for some time, especially
with microwaves. In the 1940's, while he
was manufacturing microwave diathermy
equipment, Lee de Forest suggested a
study of "the non -thermal effects of
higher radio frequencies." Some effects
of radio waves are rather sharply tuned:
ants align their antennas parallel to an
electromagnetic field at 9 MHz; emissions at 29 -MHz have been used to kill
bugs in bread, and radiations at 388 MHz have killed monkeys. On the other
hand radiation at 21 -MHz increases the
germination of gladiolus bulbs. These
are obviously non -thermal phenomena;
effects due to heat would cover wide
frequency bands.

Emergency audio transmitter

is help for seizure victims
A device for persons who may be
liable to heart attacks, epileptic seizure
or diabetic coma is now being marketed
by a Denver firm.
Called the Emergency Medical Instructor, it is a small case that contains
a taped message pre- recorded by the
patient's own physician, telling what is
(continued on page 12)

Avoid serious trouble in color TV sets

by using the rim replacement capacitor!
I

SA
SPRAGUE

polyester
film

TYPE PM

These capacitors
are a MUST for critical

This capacitor is GREAT for

90% of your film capacitor

replacements. But
it's NOT
designed for certain
critical applications.

...

commutating and S -shop rig

applications.

The next time you replace a dipped tubular in one

of the newer color TV sets, don't automatically
assume you're replacing an ordinary every -day
film or paper capacitor. If it happens to be a deflection capacitor used for commutating or S- shaping,
you need a polypropylene or polycarbonate film
replacement with (1) high a -c current -carrying capability; (2) close capacitance tolerance; (3) good
capacitance stability. The standard replacement

SPRAGUE
F @ WVDC
1.75

@ 100

1.5

@ 150

@ 400
.015 @ 400
.033 @ 400
.06 @ 400
.081 @ 400
.2
@ 400
.01

.0018 @ 600
.0022 @ 600

Cap. Tol.

5%
5%
5%
5%
5%
5%
2%
5%
5%
5%

capacitors used in the industry, even our superior

Type PS dipped tubulars, just won't do the job .. .
and they could cause serious trouble after the set
is put back into operation.
Play it safe ... dipped tubulars may lock alike
on the surface, but there can be a big diffor?nce in
the film dielectric. Keep a supply of Sprague Type
PP and PM capacitors on hand for thoso critical
situations where ordinary replacements won't work.

YPE PP POLYPROPYLENE FILM

PE PM POLYCARBONATE FILM

D. x L.

Cat. No.

.900

1.000

PM1-M1.75

.800

.937

PM15-M1.5

.400 x
.450 x
.500 x
.800 x
.600 x
.700 x

.750
.750
.750
1.250
1.300
1.700

.400
.400

x
x

.750
.750

PP4-S10
PP4-S15
PP4-S33S
PP4-S60S
PP4-S81S
PP4-P20
PP6-D18S
PP6-D22S

CAPACITORS

WVDC

.0039 @ 600
@ 600
.01
.066 @ 600
.075 @ 600
.022 @ 800
.047 @ 800
.051 @ 800

.0018
.002
.0033
.0039

@
@
@
@

1600
1600
1600
1600

Cap. Tol.

5%
5%
5%
5%
3%
5%
5%
5%
5%
5%
5%

information on close -tolerance polypropylene and

polycarbonate film capacitors, showing original part numbers with
correct Sprague replacements, ask your Sprague distributor for Cross Reference Guide C -873, or write to: Sprague Products Company,
81 Marshall Street, North Adams, Mass. 01247.

.400
.500
.800
.750

.600
.700
.800

.500
.500
.550
.600

x
x

x
x

.
Cat. No.

D. x L.

.800
1.250
1.250
1.250

PI'6-D39S
PI'6-S l OS
PI'6-S66S

1.300
1.250
1.250

PI'8-S22S
PI'3-S47S
PI'8-S51S

1.300
1.300
1.300
1.300

PI'16-D18
PI'16-D20

PI'S-S75S

PI' 16-D33
Pf' 16-D39

For cross -reference

THE BROAD -LINE PRODUCER OF ELECTRONIC PARTS

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reader service card

www.americanradiohistory.com

SPRAG
THE MARK

OF

REE

E
LITY

Whe do
the pros geit
training?

ffr

41.)

l
z
U
Eiw

----------

Almost half of the successful TV servicemen have

home study training and among them, it's NRI 2 to
1. It's a fact! Among men actually making their living repairing
TV and audio equipment, more have taken training from NRI
than any other home study school. More than twice as many!

8
www.americanradiohistory.com

Not only that, but a national

survey* performed by an
independent research
organization, showed that the
pros named NRI most often as
a recommended school and as
the first choice by far among
those who had taken home
study courses from any school.
Why? Perhaps NRI's 60 -year
record with over a million
students...the solid training
and value built into every NRI
course. .. and the designed -forlearning equipment originated
by NRI provide the answer.
But send for your free NRI
catalog and decide for yourself.

Two Famous Educators...

NRI and McGraw -Hill.
NRI is a part of McGraw -Hill,
world's largest publishers of
educational material.
Together, they give you the
kind of training that's geared
for success .. ;practical know how aimed at giving you a real
shot at a better job or a
business of your own. You
learn at home at your
convenience, with "bite- size"
lessons that ease learning and
speed comprehension. Kits
designed to give you practical
bench experience also become
first -class professional
instruments you'll use in your
work.
*Summary of survey results upon request.

25" Diagonal Color TV...

Professional Instruments
As a part of NRI's Master
Course in TV /Audio servicing,
you build a big-screen solid
state color TV with every
modern feature for
great reception and
performance. As you
build it, you perform
stage -by -stage
experiments designed
to give you actual
bench experience
while demonstrating
the interaction of
various stages of the
circuitry. And your
TV comes complete
with console cabinet,
an optional extra
with other schools.
Likewise, NRI's
instruments are a cut above
the average, including a 31/2
digit precision digital
multimeter, triggered sweep 5"
oscilloscope, and integrated
circuit TV pattern generator.
They're top professional
quality, designed to give
you years of reliable service.
You can pay up to $800 more
for a similar course and not get
a nickel's worth extra in
training and equipment.

RI
W)
mr.
I

Widest Choice of
Courses and Careers,.
NRI doesn't stop with ju -: one
course in TV /Audio servicing.
You can pick from five
different courses (includini; an
advanced color course for
practicing technicians) so 3 ou
can fit your training to your
needs and your budget. Or,
you can go into Computer
Technology, learning on a real,
digital computer you build
yourself. Communications
with famous Johnson
transceiver. Aircraft or Marine
Electronics. Mobile radio,
and more.
Free Catalog...

No Salesman Will Call.

Send the postage -paid card
for our free color catalog
showing details on all NE I
electronics courses. Lesson
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opportunities are fully
described. Check card for
information on G.I. benefits.
No obligation, no salesnaa n
will call. Mail today and see
for yourself why the prop
select NRI two to one!
If card is missing, write to:

NRI SCHOOLS
McGraw -Hill Continuing

Education

CE ter

3939 Wisconsin Avenue,

Washington, D.C. 20016
11

www.americanradiohistory.com

new so ti
happening, the identity of the victim,
and giving necessary instructions for
emergency action. If the wearer falls to
the ground, the device starts and continues to repeat the 4-minute message
loud enough to attract attention, for up
to two hours.
The manufacturer, National Identification Co., believes the equipment will
save lives, since in the past some such
cases have been mistaken for ordinary
drunkenness and correct treatment delayed until too late.

Microneurosurgery is aided
by compact color TV
Microneurosurgery -operation under
microscope -has been hampered by
the fact that no more than two persons
can watch the operation. Using extremely small surgical instruments, one
surgeon operates looking through a binocular microscope while the other
viewer uses the second lens of the
binocular. This not only limits the possibility of training other surgeons, but
places the surgeon in an isolated position, as the operating room staff are
unable to observe the operation and
therefore cannot intelligently anticipate
the surgeon's needs.
With the help of a new compact color
TV camera, devised by Motorola, New
York's Mount Sinai hospital has overcome these difficulties. Since the size
of the new camera permits connecting
it directly to the microscope, the operation can be telecast to TV sets in the
a

mCI'y(Cfltifliedfrofl? page

operating room exactly as

sees it. The operation can
corded on videotape as an
ing future surgeons for the
tion.

6)

the surgeon
also be reaid in trainsame opera-

Auto license plate

to go electronic?
An electronic license plate proposed
by Dr. Fred Sterzer, director of the RCA
Microwave Technology Center in Princeton, NJ, may make that now little regarded part of the car an important
factor in highway safety, vehicle scheduling and control, theft protection, and
traffic control.
The device is described as "a printed circuit antenna covered by a visual display of the license number, a frequency
doubler, a modulator and an rf detector." It would receive signals on an assigned frequency and retransmit them
on double that frequency. An integrated
circuit encoder would enable the license
plate to transmit a signal that would
identify the vehice carrying it. Costing
only a few dollars to make in quantity,
the electronic license plate could:
1. Respond with a vehicle's identifying code when interrogated electronically. (Electronic interrogators (transponders) placed along streets and
highways, and connected into a data processing network could schedule or
dispatch ambulances, police cars, trucks
or busses more efficiently. Trucking
firms could reduce the risk of highjacking by monitoring the progress of trucks

carrying valuable cargo. Interrogators

could search for cars reported stolen,
or report those whose owners were
ignoring summonses for traffic violations.)
2. Receive and transmit messages to
and from a vehicle. (The driver of a disabled car could transmit a coded call
for assistance to fixed roadside receivers
or to highway patrol cars, and could
receive safety messages -or special
calls from police vehicles, addressed
directly to him.)

3. Serve as a transponder for a collision- avoidance radar. (The electronic

license plate meets all the requirements
for a second -harmonic reflector, as used
in the second -harmonic highway collision avoidance radar demonstrated by
RCA in 1972. Such radars avoid the
clutter and confusion faced by ordinary
radars, since they see only the signal
twice the frequency
transmitted
from the electronic license plate instead
of the reflection of the direct transmitted
signal, which can be bounced off roadside objects, cars approaching in the
opposite lane, etc.)
While the adoption of such a radar
system would -like the present adoption
of safety seat belts- require legislation
or mass manufacturer cooperation, Dr.
Sterzer believes that such action would
be well- advised. "One person is injured
every six seconds and one is killed
every ten minutes in the United States,"
he says. "Increased control over motor
vehicles would be a cheap price to pay
for reducing this slaughter."

-at

Television inventor Zworykin

is unhappy with today's TV

LEFT, televises in color

COMPACT COLOR TV CAMERA, SHOWN IN PLASTIC AT EXTREME
what the operating neurosurgeon sees through his microscope lens.

www.americanradiohistory.com

Vladimir K. Zworykin, celebrating his

85th birthday, stated that to him the best
control on the TV set is now the "off"
switch. In language reminiscent of de
Forest's "What have you done to my
child ?" speech, he said: "When TV

(continued on page 14)

MARK TEN

B,

THE GAS SAVING, PLUG SAVIN

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With a Mark Ten B Capacitive Discharge Ignit on System under the hood of your car great
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Many operational problems caused by
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DELTA
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13

vesati lE new sr t I m e I Y
is

(cori,,,,c,i,,o,nage,>)

enjoyaBle
broadcasting began to develop, hoped ing secretary, Dick Jones,
that it would be used for educational Kingston.
purposes, especially so that different
cultures could learn to understand each Lessons from satellite
I

also

of

other. Instead, most of the time when teach teachers to teach

turn on the TV-bang, bang, bang!"
The first instructional television proThe Russian -born inventor, working gram to be broadcast by a satellite has
for Westinghouse in 1923, demonstrated been originated by the University of
a crude television camera and receiver. Kentucky at Lexington. One program is
When the head of his department saw it, designed to show teachers how to
Zworykin revealed, he said: "Put that teach children about adult careers, anguy to work on something more useful!" other includes lessons on conducting
Later, Zworykin took his neglected de- remedial instruction. The first programs
vice to RCA, where Sarnoff saw its were carried by land line from Lexingpossibilities and supported it to the ton, KY, to Rosman, NC, and transmitted
ultimate commercial success.
from there to Applied Technology
Satellite 6, for re- transmission to waitCETA of Poughkeepsie area
ing teachers from Huntsville, AL, to
elects its 1974 -75 officers
Fredonia, NY.
Ron Palluth, CET, of Poughkeepsie,
A New York Times reporter, covering
NY, was re- elected president of the 15 schools in the Applachian area, reConsumer Electronics Technicians As- ports that signals from AT -6 came
sociation (CETA), at a meeting held at through strong and clear.
the Kitchen Restaurant, Hyde Park, NY,
Other educational and medical prolast June. Vice president is Ken Parese, grams were planned for later in the
CET, of Wappingers Falls, also re -elec- year, and it is anticipated that next year
ted. Treasurer is Tom McNamara, Salt the satellite may be shifted farther east
Point; recording secretary Dan Ells- to transmit educational programs for
worth, CET, Kingston, and correspond- 5000 villages in India.
R -E
I

...

1 50
is the finest and most
versatile control unit I have ever used.
For the first time l can hook all my
equipment together at once. l find
many semi -pro operations possible
with it that l have never been able to
pull off, including a first -class equalization of old tapes via the smooth and
distortionless tone controls. I have
rescued some of my earliest broadcast tapes by this means, recopying
them to sound better than they ever
did before.
--Ed Canby, AUDIO

This

Among the things you can do with an IC150:

Produce your own taped programs! Record
from any of seven inputs: 2 phono, 2 tape,
1 tuner, 2 auxiliary (tape player, cassette
deck, guitar, microphone, etc.)
Clean up record scratch, tape hiss and
turntable rumble with filters which scarcely alter program material.

Improve frequency response with bass

and treble controls for each channel.
Enhance stereo image with the IC150's
exclusive panorama control.
Record two copies of a program at once,
and monitor source and tape for each. Or,
record on one tape deck while listening
to a second tape
Recreate original placement of soloists,
small groups and actors, regardless of
speaker position.
The IC150 performs all these functions and more with lower distortion and
noise than any other preamplifier. This
combination of clean sound and versatility
cannot be bought anywhere else for less
than $600. But you can buy it for only $349
at your Crown dealer. See him today to
make your own comparison.
For independent lab test reports on the IC150,

write CROWN, Box 1000, Elkhart, Indiana, 46514.

0 crown

Radio-Electronics is published by Gernsback Publications, Inc. 200 Park Ave. S.

New York, N.Y. 10003 (212) 777 -6400
President: M. Harvey Gernsback
Secretary: Bertina Baer

Circle

6 on

Don't miss

single copy of
ADVERTISING SALES
EAST
Stanley Levitan, Eastern Safes Mgr.
Radio -Electronics
200 Park Ave. South
New York, N.Y. 10003
(212) 777 -6400

MIDWEST/Texas/Arkansas /Okla.
Ralph Bergen
The Ralph Bergen Co.
6319 N. Central Ave.
Chicago, Ill. 60646
(312) 792 -3646

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Jay Eisenberg
J.E. Publishers Representative Co.,
8560 Sunset Blvd.,
Suite 601,
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(213) 659 -3810
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1485 Bayshore Blvd., Box 140
San Francisco, Calif. 94124
(415) 467 -0125

MADE ONLY IN AMERICA

14

MOVING?

reader service card

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Radio -Electronics. Give

ATTACH

us:

LABEL

Six weeks' notice

HERE

Your old address and zip

code

Your new address and zip

code
name

(please print)

address
city

zip code

state

Mail to: Radio -Electronics

SUBSCRIPTION DEPT., BOULDER,
80302

COLO.

The TELEQUIPMENT D61

is a low priced 10 MHz dual
trace oscilloscope with sweep
rates up to 100 ns /div. It is ideally
suited for students, technicians,
and hobbyists.
Operating Ease. Front
panel controls are engineered
for instant recognition. Line or

No other
10 MHz

oscilloscope
gives you all
this for $475

intensity

focus
in.nrr

...

Because of its X -Y capability,

the D61 simplifies alignment
and troubleshooting of color
television sets. Its performance
equals or exceeds the requirements for servicing audio
equipment, pocket calculators,
public safety control, alarm,
and communications systems,
microwave ovens, digital clocks,
and similar consumer electronic products.
Compact, portable. Fully
transistorized. and weighing
only 15 pounds, the D61 occupies only 6.3 inches of bench
width. It's easy to transport and
use in confined working areas.

probe test

cal 0 5vpp

time,, division
2

ms

70

20

.2

SO D

'',/1.

21

VOS

02

Tektronix reliability.

I 500200

oaMN.

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k.

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50

:20
10

is

too a

20001

volts/ division
.5

IMO

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500
eat

Bright, stable viewing.

Stable waveforms, displayed on
an 8 x 10 cm crt, are easy to
view, even under unfavorable
ambient light conditions. Two
identical input channels simplify generation of X -Y displays.
This is particularly useful in
analysis of vector patterns.

Application versatility.

_OPF'

xxoNsele

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frame displays are selected

automatically in the TV trigger
position. And, chopped or
alternate modes are determined automatically to
optimize display clarity.

1.02

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TELEQUIPMENT products
carry the well -known Tektronix
warranty and are marketed
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ch 2
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trig level
pull - auto)

input

Automatic triggering.
TV Frame
and line triggering.
Dual-trace, XY
and vector modes.
me the D61 Spec Sheet and Teleau ornent
catalog.
Have your field engineer call to arrange a
demonstration.
Tektronix, Inc P 0 Box 500. Beaverton, Oregor 9'

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Title
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Address
City

Zip

State

TEKTRONIX

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www.americanradiohistory.com

u'rlr

16 ritt reader

1rrrirr rurll

I11)

dr;++n^Nrulinn

15

letters
MORE NEW TECHNOLOGY
PLEASE!

would like to say that your magazine

excells above the other publications
when it comes to quality construction
projects such as the character generator of the September 1973 issue. I'm
sure you have received many letters
appreciating this.
did send for the
booklet also which feel was well worth
the cost. I have not as yet built the
project, but plan to in the near future.
would like to see more projects of this
caliber. I would especially be interested
myself in monitor -receiver projects.
I like the idea of your
magazine presenting new technology to its readers.
Computers are now a part of our lives
and with the number of calculators now
on the market, we service technicians
need all the updating we can get. No
schooling is available of decent quality
to aid technicians to service such
equipment, so most people are forced
to pay large service fees for manufacturer- oriented service personnel.
The quality of technicians in general
is below what it should be overall. The
I

licensing program will help tremendously. Shop owners should encourage the study and acquisition of
CET certificates to their technicians.
Right now, many shop owners either
don't seem to know or don't care if a
technician even possesses such a
certificate.
Thank you again for the opportunity
to "sound off."
GERALD F. CLEMENT JR.
Canoga Park, Calif.
CET

City of New York

Dept. of Consumer Affairs
80 Lafayette Street
New York, NY 10013

Elinor Guggenheimer,
Commissioner
Dear Mrs. Guggenheimer:
Re: Chapter 32 title b Art. 44 Admin
code.
Thank you for sending us a copy of
the New York City Rules and Regulations relating to TV, Radio & Audio
Equipment repairs. The following are
the observations I have:
1. Estimates have always been and

are now a most difficult problem for

technicians. Often, diagnosing a problem from the symptoms displayed can
lead even the best practicing technicians to believe a certain part is at fault
when, in the end, it turns out something
completely different is causing it. By
requiring an estimate as outlined in
the law, the technician and dealer are
asked to be very accurate or face a
loss or try to amend the estimate later.
realize this is a most difficult area
you have to deal with in the regulations,
but it is one where after some experience, your department may want to
modify the rules. This may benefit the
dealers by relaxing the procedures
while benefitting the set owner by allowing the dealer-tech to give more accurate estimates without over -protecting
himself.
NESDA (National Electronic Service
Dealers Association) is very interested
in your experience in this regard and
would be most happy to have your opinions on it, later, for our use in helping
other areas solve problems in their
legislation.
(continued on page 22)
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The FM- 2400CH with its extended range
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It takes more

learn about

Schools introduces three

fascinating learn -at -home programs featuring
some of the finest equipment available as your
"teachers." Choose the program you prefer
then mail card for free details today!
Bell & Howell

Experience is the best teacher, without a doubt.

And when it comes to learning electronics, we feel it's
hands -on experience with state -of- the -art equipment
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Schools'learn -at -home programs you work with some of
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Of course, with all our learn-at -home programs
you'll have plenty of lab manuals and basic principles to
work with. And you'll also get exciting "teachers" to help
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Lab Starter Kit gives you hands -on experience
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We get you started with the basics in an exciting
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them at work!

As you put the set together, you'll discover

how advanced integrated circuitry works, how to
trouble -shoot it and much more. Upon completion
of the program you'll have gained the specialized
occupational skills to service color TV's plus the
principles that you can apply to repair a variety of
home electronic equipment. And you'll have the
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II. Use proressional communications equipment as

you delve into Communication Electronics .
Here's how to pick up skills in the vital field
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industrial and transportation areas. Bell & Howell
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help prepare you for the FCC licensing exam, right
through to l st class radiotelephone operator. And
teach you skills in two -way radio, radar or commercial

broadcasting.
For a refundable deposit, you get to use the
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featuring an FM transceiver,
frequency meter, and
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grade test equipment.

You build your own Electro -Lab " electronics

training system.
Whatever program you choose, you get
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skills in the field of Home

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building the new generation color TV.
What better or more exciting way

I. Learn new

to learn digital electronics! Once you have

the basics under your belt and get into color
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' Electro-Lab" is a registered trademark

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Simulated TV Picture /Test Pattern

www.americanradiohistory.com

of the Bell L

than books to

electronics.

integrated circuits so you'll have a solid background it

modern digital electronics and its applications to industy.

Ill. Digital Trainer helps you learn the latest in

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Digital technology is setting new standards

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And now you can learn
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You study at home in your spare time ..

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Because these are

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You study at your convenien:
without being a classroom
captive. If you ever have any
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You can also meet and talk shop
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50 cities at various times throughout the year
Bell b Howell Schools tries to give you more
personal attention than any other learn -athome program.

Decide which exciting program

you're interested in ...you can chec'<
more than one. Then mail postage paid card today for free
information -no obligation!
Taken for vocational purposes, the Home
Entertainment and Industrial courses are
approved by the state approval agency for
Veterans' Benefits. Please check box on card
for free informatic1. Power

Design Console 3. Modt.lation

Meter ; igital Multimeter 5. Trigge'e 3
Sweep Oscilloscope 6. Lab Starte Kit
Multimeter 7. Frequency Meter 3. FM
Transceiver 9. 25" Diagonal (lo or
TV 10. Alignment Generator
1 1. Lesson Tape Player
12. Digital Trainer

Output M.

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as been removed. pleaae rite to:
An Eleatr --ss Home Study Schoc!
De1IRV IfSTITLITE OF TECHnOLOGV

BELL E HOWELL SE:I-TOOLS

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21
www.americanradiohistory.com

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HOBBY PROJECTS & PLANS

of Books for the Libraries

Checklist
of Technicians.

Hobbyists

&

Students

Electronics For Shutterbugs. 156 p.. 84 d0

RF & Digital Test Equipment You Can Build. 252 p
217 1,1
Practical Circuit Design for the Experimenter. 192 p 119 dl
Pract. Triac /SCR Proj. For The Experimenter. 192 p.. 146 i0.
Professional Picture Framing For The Amateur. 168 p., 136
Miniature Projects For Electronic Hobbyists. 168 e., 77 ill
Digital Electronics: Principles & Practices. 288 .0., 191 ill
New IC FET Principles and Protects. 160 p over 60 ill.
Handbook of IC Circuit Projects. 224 p 136 ill.
Stereo /Quad Hi-Fi Principles and Projects. 192 p.. 100 ill.
64 Hobby Projects For Home & Car. 192 p
159 rII
How To Build Solid -State Audio Circuits. 320 p
190 dl.
Solid -State Projects for the Exper. 224 p., 228 ill.
104 Ham Radio Projects For Novice & Technician, 192 p.
Electronic Hobbyist's IC Project Handbook. 160 p.. 86 ill.
Radio -Electronics Hobby Projects. 192 p., 214 ill
VHF Projects for Amateur & Experimenter. 224 p.. Il.
125 One- Transistor Projects. 192 p., 125 ill.
Practical Solid-State Principles & Projects. 176 p., 127 ill.
IC Projects for Amateur & Experimenter. 192 p., 252 ill.
Id 104 Easy Projects for the Electronics Gadgeteer. 160 p.
D 104 Simple One -Tube Projects. 192 p., 104 ill.
Ll 104 Easy Transistor Projects You Can Build. 224 o 105 ill.

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AUDIO HI -FI & TAPE RECORDERS

Electronic Music Production. 156
Auto Stereo Service

&

53 95

Installation.:

Stereo'Ouad Receiver Servicing Manual

.II.
Experimenting With Electronic Music. 18i
Cassette Tape Recorders /How They Work /Care & Repair. 2.;4
Questions & Answers About Tape Recording. 264 p.. 102 dl.
FM

p.

-From Source to Sound. 1', D 98 dl

lap Radio, Record & Tape Player Svcing. Manual. 812,11"
Acoustic Techniques for Home and Studio. 208 p 168
Basic Audio Systems. 240 0
201
Selecting & Improving Your Hr-Fr System. 224 p., 122 III.
Pictorial Guide to Tape Recorder Repairs. 256 p.. 120 III
How to Repair Musical Instrument Amplifiers. 278 p.. 110 ill
Servicing Electronic Organs. 8, 211" 196 p.
Electronic Musical Instruments. 192 p., 121 in
Svcing Modern Hi-Fi Stereo Systems. 248 p
125 u.
Handbook of Magnetic Recording. 224 p., 90 ill.
Installing and Svcing. Home Audio Systems. 256 p 150 u.
Tape Recording for Fun & Profit. 224 p., over 200 ill.
4- Channel Stereo

Audio Systems

Handbook.

192 p.,

128

ill.

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AUTO ENGINE & APPLIANCE REPAIR

I

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The Comp. Hdbk. of Auto Engines & Systems. 218

239

ill

Rapid Auto Tuneup & Troubleshooting. 180 p.. 97 ill.

The Complete Snowmobile Repair Handbook. 348 p.

Modern Guide To Auto Tuneup & Emission -Control Sine. 240 p

How to Repair Small Gasoline Engines. 256 p
H. Everyman's Guide to Auto Maintenance. 192 p., 38 ill.
L' The Complete Minibike Handbook. 320 p., 145 ill.
I7 Using Electronics Testers for Auto Tuneup. 256 p., 226 ill.
Ll Major Appliance Repair Guide. 260 p., dl.
D Small Appliance Repair Guide. 224 p., 100 ill.
D How to Repair Home & Auto Air Conditioners. 208 p., 100 ill.
I

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LI Refrigeration.

148 0.. 53

ill.

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HAM RADIO, COMM'S., B'CASTING., CATV

Amatuer FM Conversion 6 Constr. Projects. 276 p., 187 ill.
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Class FCC Study Guide. 156 p., 191 ill.
The Complete Shortwave Listeners Handbook. 288 p., 101 ill. $6.95
D How To Be A Ham -Including Latest FCC Rules. 192 p.
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Ll Commercial FCC License Handbook. 444 p.. 150 ill.
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The 2 -Meter FM Repeater Circuits Handbook. 312 p., 182 ill.
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C Mobile Radio Handbook. 192 p., 175 ill.
El Pictorial Guide to CB Radio Installation 6 Repair. 256 p. ill. $4.95
Ll RTTY Handbook. 320 p., 230 ill.
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D Design. and Main. the CATV & Small TV Studio. 256 p.
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'1 Video Tape Prod. 6 Common. Techniques. 256 p., 100 ill.
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CATO Systems Engineering-3rd Ed. 256 p.. ill.
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L' CB Radio Service Manual. 228 p., 98 ill.
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D CB Radio Operator's Guide. 224 p., 248 ill.
AMATEUR RA010 STUDY GUIDES: Cl Novice $3.95 D General $6.95
D Advanced $3.95
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Beginner's Guide to Computer Programming. 480 p., 364 ill.

I1 Simplified Computer Prog. /The

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Computer Technician's Handbook. 480 p., 400 ill.

Beginner's Guide to Computer Logic. 192 p., 100 ill.
Computer Circuits & How They Work. 192 p.. ill.

ELECTRONIC SERVICING
Effective Troubleshooting With EVM & Scope. 240 p.
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D Pinpoint Transistor Troubles in 12 Minutes. 492 p., 243 ill. $6.95
D Troubleshooting Solid -State Amplifiers. 256 p., 95 ill.
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D Electric Motor Test and Repair -2nd Ed. 160 p.
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C How to Solve Solid -State Circuit Troubles. 304 p., 161 ill.
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D Trblshting Solid -State Electronic Power Supplies. 208 p., iii. $4.95
MATV System Handbook: Design, Inst. & Main. 176 p., 91 ill. $4.95
D A Practical Guide to MATV/CCTV Sys. Design 6 Sere. 252 p. $5.95
D Professional Filmmaking. 252 p., 96 ill.
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D Radio Advertising -How To Sell It 6 Write It. 228 p.
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C Practical Electronics Servicing Techniques. 256 p.
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10- Minute Test Techniques for Electronics Servicing. 176 p.
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D Solid -State Circuit Troubleshooting Guide. 224 p., over 150 ill. $4.95

Switch, $6.95 D Garage Light Control, $9.95 E Audio Signal Generator

Infector, $5.95 D Low Voltage DC Power Supply, $4.95 D Diode Tester,
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ELECTRONIC TEST EQUIPMENT

How To Tblsht. & Repair Elect. Test Equip. 228 p., 143 ill.
How To Use It, 204 p., 132 ill
Electronic Test Equipment

-6

240 p., 217 ill.

Practical Test Instruments You Can Build. 204 p., 157
How to Test Almost Everything Electronic. 160 p., 114
Understanding & Using the Scope. 272 p. 170 ill.
Basic Electronic Test Procedures. 416 p., 178 ill.

D Electronic Measurements Simplified.

D
D
D
D
D

-A

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Basic Radio Course. 224 illustrated

Basic TV Course. 224 p., 128 ill.
Electronics Self- Taught with Exp. &
Model Car Racing by Radio Control.
_I Basic Electronics Problems Solved.
1

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224 p.. 250 ill.
192 p., over 100 ill.

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RADIO & TV SERVICING

C

244 ill.
Quick -Ref. Symp. Guide.
Antennas. 168 p., 158 ill.
Color TV Trouble Fact Book-2nd Edition, 348 p.
TV Bench Servicing Techniques. 228 p., 177 ill.
10- Minute Test Techniques For PC Servicing. 216 p., 114 ill.
TV Tuner Schematic /Servicing Manual. 224 p.
Japanese Consumer Electronics Service Manual. 196 p., 81/1x11
Pinpoint TV Troubles in to Minutes. 372 p., 394 ill.
Rwik -Fio TV Service Manual. 384 p., scores of charts
Modern Radio Repair Techniques. 250 p., plus 36 -p. foldout
Pictorial Guide to Color TV Circuit Troubles. 256 p., 262 ill.
125 Typical Elect. Cir. Analyzed & Repaired. 208 p., ill.
Simplified TV Trouble Diagnosis. 320 p., 292 ill.
199 Color TV Troubles & Solutions. 224 D
All -In -One TV Alignment Handbook. 304 p., 145 ill.
Basic Color Television Course. 420 p., over 300 ill.
Home -Call TV Repair Guide. 144 p., charts
How To Interpret TV Waveforms. 256 p_ over 250 ill.
199 TV Tough -Dog Problems Solved. 252 p., 199 ill.
101 TV Troubles-From Symptom to Repair. 224 p., 170 ill.
Servicing The Solid -State Chassis. 256 p., ill.
On The Color TV Service Bench. 192 p., heavily ill.
CET License Handbook. 276 p.,
Logical Color TV T'shooting

a Installing
D
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REFERENCE & GENERAL ELECTRONICS

ill.
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& Using the VOM & EVM. 192 p., 187 ill.
99 Ways to Use Your Oscilloscope. 192 p" 327 ill.
Working With The Oscilloscope. 104 p. 81/2x11", 183 ill.
How to Use Test Instruments in Electronic Svcing. 256 p.

Understanding

Modern Communications Switching Systems. 276 p., 171 ill. $11.95

Getting The Most Out Of Your Elect. Calculator, 204 p., 18 ill. $4.95
Indexed Guide To Modern Electronic Circuits, 216 p., 92 ill.
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D Modern Applications of Linear IC's, 276 p., scores of ill.
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D Solid -State Circuits Guidebook, 252 p., 227 ill.
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D T'skting. Solid -State Wave Gen. & Shaping Cir. 192 p., 78 ill. $4.95
D Handbook of Semiconductor Circuits. 444 p.
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Basic Math Course for Electronics. 168 p.
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D Dictionary of Electronics. 420 p., 487 ill.
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Intro. to Medical Electr'o. for Elect. /Med. Pees. 272 p., 126 ill. $6.95
C Fire & Theft Security Systems. 176 p., over 100 ill.
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D Tube /Transistor Substitution Guide. 256 p.
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D Marine Electronics Handbook. 192 p., 106 ill.
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D Handbook of Electronic Tables -2d. Ed. 224 p.
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D Solid -State Circuit Design & Operation. 272 p., 150 ill.
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D Electronics Data Handbook -2d. Ed. 256 p.
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L1 Pulse & Switching Circuits. 258 p., 184 ill.
D Modern Radar: Theory, Oper. and Maint. 480 p., 367 ill.
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D Passive Equalizer Design Data. 496 p., 9V2x11 ", 125 ill.
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COLOR: Sviceg. Modular
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D Audio Mixer, $7.95 D 5 -Watt Hi -Fi Amplifier, $9.95 D Electronic
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Elect. Unraveled
New Commonsense Approach. 228 p., 96 ill.
D Model Sail & Power Boating, by Remote Control. 192 p., 103 ill.
Electrical Wiring 6 Lighting For Home & Office. 204 p., 155 ill.
LI Basic Electricity and Beginning Electronics. 256 p., 191 ill.
D Basic Electronic Circuits Simplified. 352 p., 170 ill.
D How to Read Electronic Circuit Diagrams. 256 p., 140 ill.
D Basic Electronics Course. 384 p., 275 ill.
I Beginner's Guide to TV Repair. 176 p., 80 ill.
Ll How To Become a Radio Disc Jockey. 256 p., 25 lessons

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TAB BOOKS, Blue Ridge Summit, Pa. 17214

Please send me books checked above.
I enclose $
Please invoice on 10 -day FREE trial.
Send FREE 36 -page catalog.
Name

Circle

10 on

2. Reg. No. 11 would be interpreted

by a majority of judges as meaning any
(TV -Set, Stereo, Radio, etc. as a unit)
must be warranted or guaranteed, both
parts and labor.
don't think that is
your intent, but it must be spelled out
I

that only those parts replaced and only

the actual repair work charged for are
guaranteed. As is, the dealer is expected to be a philanthropist, possibly
repairing an inexpensive item (for example) and yet being asked to warrant
the $250.00 picture tube!
3. In Indiana and in all other of the
nine states with electronic service legislation, there is an industry advisory
board. Without these experts to advise
you, some common servicing practices
may seem wrong when they are right.
To discredit a dealer unfairly or your
department would lessen the effectiveness of the regulations. Consider appointment of such a board (preferably
a five -man board).
4. The $100.00 fee for a dealer license
is quite high when compared with that
in other states.
realize that for effective administration of the law that you
will need investigators, a staff, etc. and
other items. However, other governments with fewer shops have been able
to have a greatly reduced cost for the
license to the shop.
Since this cost, as well as the other
costs in time and materials which this
regulation will impose on the dealers,
must be passed on to the set owners,
reduction of the fee would be in the
best interest of the public.
5. Equal justice under this act is so
vital. Much of the problems of the electronics service business over the years
has been caused by people performing
service with an unfair advantage. Examples of this are those servicers who
operate on a haphazard basis out of
their homes, who hide their income
thus not paying any taxes on it; who do
not protect their customers by having
insurance; etc.
If all servicers in New York have to
play the game by the same rules
equally, this law can be complied with,
with the above modifications. However,
if enforcement is not certain and swift,
the law could merely increase the cost
of service and lower its quality.
If
can be of further service to you
or the dealers and techs in New York,
feel free to call on me.
I

DICK GLASS
Executive Vice President
NESDA
Indianapolis, IN

R -E

itN working

Thanks to you

Phone

The
United Way

Company

Address
State

City

SAVE POSTAGE by remitting with order.

Foreign add 10 %. Pa. residents add 6 %.

Zip
RE-I14

22

LETTERS
(continued fron] pate 16)

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Wvsrtiainp coninb:tod
for tho pubho good

anc

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23

appliance clinic
AUTOMATIC LIGHT SWITCHES
by JACK DARR

346 Ways
To Save On

Instruments,
Burglar Alarms,
Automotive &
Hobby

Electronics!
The more you know about
electronics, the more you'll
appreciate EICO. We have a wide
range of products for you to
choose from, each designed to
provide you with the most
pleasure and quality performance
for your money. The fact that
more than 3 million EICO products
are in use attests to their quality
and performance.

SERVICE EDITOR

AUTOMATIC LIGHT SWITCHES HAVE BE-

come quite popular, not only in rural

areas but in suburban areas as well.
These switches use a very simple electronic circuit; a small relay which is
controlled by a photocell. When the
outside light is high enough, the relay
is energized and the light goes off.
Figure 1 is the schematic of a typical
unit. This is one of the smaller types,
for controlling lamps up to 300 watts.
There are several different sizes, including types which can control high intensity mercury lamps.
The ac current flows through a
5100 -ohm resistor (refer to Fig. 1),
through a cadmium- sulphide photo-

AC LINE

WHITE
BLACK

FIG.

"Build -it-Yourself" and save

up to 50% with our famous
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Electronics, Eicocraft Project kits,

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Leadership in creative electronics

since 1945.

Circle

12 on

cell (abbreviated CdS), then through

the coil of the relay. The CdS cell
here is used as a variable resistor. The
arrows are the symbol for a light actuated device.
When the cell is dark, it has a high
resistance. More light falling on it
decreases the resistance and more current flows. The relay contacts do the

actual switching. They are normally

closed ( "NC ") when the relay is not
energized, and the light goes on. This
gives us "fail- safe" operation. If anything goes wrong in the control circuitry, the light remains lit.
The control unit is usually mounted
on top of the lamp reflector, under a
small metal cover. This will have a
little window in it; the photocell is
mounted behind this. For best results,
this window should be on the north

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www.americanradiohistory.com

side of the cover when installed. This

keeps the direct rays of the sun from
falling on it, and gives better control
of the light.
To repair one of these, start with
the lamp. If the lamp won't light, replace the bulb with a good one. Now,
cover the window on the housing with
your hand. You should hear the relay
click. If this happens, but the light still
refuses to go on, turn the power off
and remove the cover. There are
several hot wires exposed, so don't

take any chances.

Check the relay contacts; they may
be burned or pitted so badly that they
do not make contact, even though the
armature of the relay may pull in. In
most of these units, the contacts are
easily accessible. Pull a strip of fine
sandpaper between them, holding the
armature down with your finger
(power OFF, remember!) Close the
relay gently by hand and look at the
contacts; you will be able to tell
whether they're touching or not. Turn
the power on, keeping clear, and recheck the unit to see if it's operating.
You can cover the photocell with a
piece of dark paper or cloth.
One common cause of damage to
these units is a nearby lightning discharge. If this has happened, you will
probably see burned parts, charred insulation or carbon "tracks" across
insulators. If this is the case, take the
unit off and repair it.
Disconnect both wires and remove
the control unit and lamp socket.
You'll need an ohmmeter to check it.
Disconnect the capacitor across the
relay coil and check it for shorts. If
it has shorted, the 5100 -ohm resistor
will probably be well charred, too. Replace these, if they're bad. Before
connecting them back, check the relay
coil. If it too, has been damaged by
the lightning, its coil will look very
dark, or even charred. Normal resistance of a typical unit is about 1000
ohms.
If the capacitor took a direct hit,
its case may have exploded, so that
you can't read the markings. Fortunately, they aren't too critical; a .01F capacitor at 600 volts is a good
size.

While the circuit is opened up,

check the photocell. With the surface

Now make almost all

your replacements with
RCA's medium - priced
Colorama A's
That's the kind of socket coverage you can
count on from this popular new "middl 3 line" of
RCA replacement color picture tubes. With
just eight Colorama A types, you can cover
almost all of the replacement market with
"Grade A" performance at a price your
customers can afford.
Every tube in the RCA Colorama A line is
totally remanufactured. That's why they all
can carry RCA's 18 -month inboarded warranty
plus the option for an additional 12 months.
Each has a completely new gun and <i completely new screen made of the latest all -new
rare -earth phosphors. In addition, every
"V" type is made of advanced x -ray glass.
The RCA Colorama A line includes three
Matrix types: CA- 21VAKP22, CA- 23VALP22
and CA- 25VABP22. These advanced RCA
Matrix tubes are as much as 100 percent
brighter than any equivalent non -Matrix
picture tube in RCA history.
So why not give your customers the "Grade
A" choice. Choose Colorama A at your RCA
Distributor today.
Remember, RCA is the world -wida leader
in picture tubes, with over 65 million produced
to date.

11

RC,'

RCA /Electronic Components/Harrison, N.J. 07029

www.americanradiohistory.com

equipment

report
Technics Model RS -676US
Dolby Cassette Recorder

Circle I

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111

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WITH EACH NEW DEVELOPMENT IN

high fidelity, manufacturers often just
dip their toes in the water while checking on what everyone else is doing.
Few take the full plunge at once.
But in the Technics (by Panasonic)
RS -676US cassette recorder, we find
virtually all the latest advancements
made in hi -fi in the last few months.
Starting off, the RS -676US is basically a Dolby cassette deck with the
addition of special switching and calibration that permits the Dolby processor to he used for monitoring (or
recording) Dolby FM broadcasts.
Next, we find the tape transport is unlike most other cassette mechanisms
you've run across. This mechanism
has two motors: one for the capstan
drive and one for a "superspeed" rewind and fast forward. Looking even
closer we find the mechanism is all
solenoid operated-the control huttolls operate only solenoids, which in
turn provide the mechanical operations. All- solenoid control means remote control is possible, and the rear
panel of this recorder has a remote control socket for an optional control
unit, or one you can easily build yourself.
Finally, we come to the peak /average VU meters used for setting the recording level. When the cassette system first made the hi -fi scene, it was
nothing more than an improved version of the basic Philips casette system, which was intended for recording speech. The reference recording
level was pegged at tape saturation for
the average program level, and signal
peaks were driven well into tape
saturation distortion
there was no

www.americanradiohistory.com

"headroom ". To maintain an acceptable signal -to -noise ratio, the reference recording level for hi -fi was maintained at tape saturation; a colossal
blunder, because the tape got better
but the signal level was still driving
program peaks into tape saturation.
With the newer tapes plus Dolby
B noise reduction, the signal -to -noise
ratio is sufficient to permit reducing
the average program level to provide
"headroom ", and that's just what Panasonic has done in their latest recorder. The 0 -VU record level is 6 -dB
below tape saturation. When the VU
meters are switched to NORMAL the
meters indicate as do any other level
meter, the difference being that 0 -VU
is 6 -dB below 2% total harmonic distortion (from the tape).
So in one package we find the latest
developments in hi -fi: Dolby FM,
automatic chromdioxide equalization
switching, cassette tape "headroom ",
solenoid operation and superfast tape
wind.
There are controls for record input
selection, line /tuner record level, record balance, and concentric left and
right microphone record level. There
are switches for Dolby B in /out /filter,
Dolby FM in /out, tape type and
peak /normal VU meters. Left and
right screwdriver -adjust controls on the
front panel permit calibration of the
Dolby FM circuit to 50% modulation
-the Dolby reference level for FM
broadcasts. (FM stations transmit the
calibration tone once or twice a day;
and once the controls are adjusted
their setting is permanent as long as
the same FM tuner is used.)
The FCC has recently allowed Dolby FM stations to use a 25 -4 pre emphasis instead of the standard 75
ItS. The recorder has a 75/25 AS
COMPENSATION switch on the rear to
permit optimizing recording and reception of either pre- emphasis. When
the recorder is set to Dolby FM, the
output to the amplifier's tape monitor
is "flat" -the Doly processor can be
used for straight listening as well as
recording.
The tape mechanism has pushbut(continued on page 110)

lt a mocJ, mod. modular world.

-

Simplify, simplify! Instead of paying more for bigger, bulkier audio control
components, pay less for compact Shure modular component!: that
singly or in combination-handle critical functions flawlessly. Cases ill point:
(1) the M67 and M68 Microphone Mixers, the original high- perfor-nance,
low -cost mixers; (2) the M610 Feedback Controller, the compact component
that permits c ramatically increased gain before feedback; (3) the M6 :I Audio
Master, that gives almost unlimited response shaping characters! ;tics; (4)
the M688 Stereo Mixer, for stereo recording and multi -source auc is -visual
work; (5) the M675 Broadcast Production Master, that works with o ur M67
to create a complete production console (with cuing!) for a fraction of the
cost of conventional consoles; and (6) the SE30 Gated Compressor 'Mixer,
(not showy above) with the memory circuit that eliminates "pump n3." For
more on how to "go modular," write for the Shure Total Commuiii :ations
Components Catalog No. AL280.
Shure Brothers Inc.
222 Hartrev Ave., Evanston, Ill. 60204
In

Canada:

A. C.

Simmonds

Circle

14

Sons, Linutod
on reader service card
&

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r =31

27

The better the

the better if
SOLID STATE
OSCILLOSCOP

COMPU- TRAINER

TUBE & TRANSISTOR

TESTER

)IG ITAL
NIRTIMETER

ELECTRO - LAE

NTS DIGITAL GR -2000 SOLID STATE

COLOR TV WITH 315 SO. IN. PICTURE

TROUBLESHOOTER
VDM

AND VARACTOR DIGITAL TUNING

As an NTS student you'll acquire the know -how that

comes with first -hand training or NTS professional
equipment. Equipment you'll build and keep. Our
courses include equipment like the 5" solid -state
oscilloscope, transistor and tube- tester,vector monitor scope, 74 sq. in. B &W TV, and solid state stereo
AM -FM receiver. The unique NTS Digital GR -2000
color TV with first ever features ''ike silent varactor

diode tuning; digital channel selection, (with optional digital clock,) and big 315 sq. in. ultra rectangular screen. This is just a sampling of the kind of

better equipment that gets you better equipped for

the electronics industry.
This electronic gear is not only designed for training; it's field type
like you'll meet on the job, or
when you're making service calls. And with NTS
easy -to -read, profusely illustrated lessons you learn
the theory behind these tools of the trade.
Choose from 12 NTS courses covering a wide range
of fields in electronics, each complete with equipment, lessons, and manuals to make your training
more practical and interesting.

Simulated TV reception

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equipment
be equipped.
411,

IN- CIRCUIT

TRANSFSTCR TESTER

HIGH FIDELITY
SPEAKERS

SOLID STATE STEREO

AM FM RECEIVER
AMPLIFIER

:OT

COLOR BAF

GENERATO

VECTOR MONITOR
SCOPE

SOLID STATE
B &W TV

F=T-\0M
5" OSCILLOSCOPE

SIGNAL
TRACER

SOLID STATE 2 -METER

FM TRANSCEIVER AND
POWER SUPPLY

Compare our training; compare our tuition. We employ no middlemen because we reed no salesmen.
We believe you have the right to make your own de -,
cisions based on the `acts, and you'll find these all
spelled out in our catalog mailing. Lessons, kits, and
experiments are described in full color. Most liberal
it's all in
refund policy and cancellation privileges
writing. And our Ilow tuition is another big advantage.
No frills, no commissions to pay. This means lower
tuition for you. You receive solid braining value. NTS
puts more into your training, so you gel more ol.t of

SOLID STATE
POCKET RADIO

SIGNAL
GENERATOR

it. Make your own decision. Mail the card, or wr it if

card is missing. There's no obligation, ever, and o

salesman will call.

Approved for Veteran Training. Get facts on ne
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A,

while the guy down the street

complains about how tough
alignments are...l do them!

/11:1MOUEL

GENERATOR
415 SOLID STATE SWEFP,MARKER

NIP

Model 415
$459
used to hook up a separate sweep generator, marker
generator, marker adder and bias supply, hope that
everything was properly calibrated and adjusted, and
pray that the alignment would hold after disconnected the cables draped all over the bench.
didn't do it very often.
Now, in the time it used to take me just to set up,
can almost complete an alignment. And I'm confident
the set will perform as well as it possibly can. My customers notice, too. That's the difference B &K's 415
Solid -State Sweep /Marker Generator made.
Setup is no problem. After connect the 415's outputs to my scope (there's even low- frequency compensation to eliminate pattern errors), connect its RF
outputs (channel 4 or 10) to the antenna terminals or
mixer test point, the direct probe to the video detector
test point (or anywhere else after the video detector
diode) and the demodulator probe to the bandpass
amplifier output.
They're all clip -on connections, and the 415 comes
with all the accessories need. Once I've made the
initial signal and bias hookups, there's nothing else to
connect or reconnect. All intercabling changes and
generator functions are controlled from the front panel.
There's even a 15,750Hz filter to eliminate disabling
I

the set's horizontal output section.

Shaping the waveform is easy, because the 415 has
10 crystal -controlled IF markers, each of which lights
up on the front -panel waveform diagram as it is used.
Markers can be shown either vertically or horizontally
on the scope trace. There's a 100kHz modulated marker that makes nulling the traps so easy it's almost
automatic. And three low- impedance, reversible polarity bias supplies -two, 0- 25VDC; one, 0- 50VDC.

Vertical Markers

Markers Tilted Horizontally

Every step is easy to understand, too, thanks to the

comprehensive manual.
Since have nothing to sell but my time, have to
make the most profitable use of it can. That's why
have a B &K 415.
In stock now at your local distributor or write
Dynascan.
I

PRODUCTS OF

DYNASCA/U

A ve.
Chicago, IL 60613 Phone (312) 327 -7270
Complete Line of Analog and Digital Multimeters, Oscilloscopes, Signal Generators,
Semiconductor Testers, Power Supplies, Probes, Tube Testers and Substitution Boxes.

1801 W. Belle Plaine

Circle

15 on

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BUILQ

zoo
Watt-Second
Photo
Build any of the three bare -bulb
photoflash units described in this article.
An optional optical trigger is also described.
by JIM GUPTON

BARE -BULB ELECTRONIC PHOTOFLASH

Optically triggered slave units are com-

units are becoming increasingly popular with amateur and professional

photographers. Soft shadows and wide
angle coverage increase the versatility
of any camera and make those "Impossible" group shots ... possible. Add
a Lawson Enterprises "Reflectasol" to
a hare -bulb photoflash and you have a
professional studio light source for
color portraits. By obtaining power
from the standard 117-volt ac line,
you eliminate the weight and expense
of batteries and have the fastest recycling time of any electronic photoflash on the market.
This article contains the construction details for three bare -bulb photo-

monly used among professional

computer -grade capacitors and has an

output of 200 watt -seconds. The second unit has an output of 100 watt seconds and uses standard photoflash
capacitors. A selectable output unit
having 50, 100, 150, and 200 watt second outputs is also described.
All three photoflash units can also

Plastic canister housing

The electronic circuits for the bare bulb electronic photoflash must he
housed in a shock -proof container.
Metal cases offer considerable physical protection, yet the metal exterior
is like:y to become charged and it will
create a shock hazard when contact is
made with a common ground circuit.
The iceal case to house the bare -bulb
photoflash can be found in the household section of most any department
store or discount house. The article's
housing was originally one of a set of
four kitchen canisters. It has rigid side
walls and ample inside dimensions to

flash units. The first unit uses

be used as slave units with an optical

trigger circuit that is described. As a
slave unit, the photoflash is triggered

with the light from

photoflash

mounted on your camera. This eliminates the need for sync cords and permits the placement of the slave unit
anywhere in the picture taking area.

photographers.
Of all electronic construction projects, none can be more deadly than
the electronic photoflash unit. Voltages
ranging between 400 and 500 Vdc, at
a current of 1 ampere, can kill you!
Therefore, every step of the construction, including the final assembly and
testing, must be and is, engineered to

protect you against accidental shock

hazards and possible fatal injury. It is
imperative that no deviation from the
specified material be attempted. When
constructing one of the three alternate
photoflash circuits, observe capacitor
polarity at all times.

house the electronic circuit securely

with complete protection from accidental shock hazards.
.

To eliminate the molded handle

grips and bottom depressiois of the
canister's top and bottom, sinrply cut
away the surface containing the raised
handle and bottom depresiois, and
replace it with a matching; .ontour
section of fiber glass priniei- circuit
board. The fiber glass board provides
a metal shielding surface and is rigid
and thin enough to support tie flash
tube circuits. They are easil! attached
to the plastic top and bottom with
epoxy cement and small slliminum
angle sections to assure firm attachment and rigidity. In my IT odel, a
metal ring surrounds the fla,,h tube to
provide mechanical protecti )r to the
tube and to serve as suppri for a
large reflector. Remember that he wall
thickness is an important itr' in selecting your plastic canister. Tie plastic walls must have enougt strength

to support the photofla ;t when

mounted on a tripod. Flexible plastics

should not he substituted as tl- cy cannot meet the support requirem:nts.
Power-capacitor bank circuit s
The schematic circuit diatram in
Fig. I illustrates two types (If capacitor banks. One type of capacitor bank
is series connected, provides a 200

33
www.americanradiohistory.com

watt -second output, and is shown in

Fig. I -a. Figure -h shows the alternate, parallel circuit which provides a
100 watt -second output.
The series circuit takes advantage
of high - capacitance computer -grade
capacitors for high output power at a

minimum of space requirements. However, there are some who may be

apprehensive about the ability of com-

A 158

D3

R3

10W

J2

30K
5W

C4

3900F
250V

C1

180/200V

C4

D1

C2

A15B

180/350V

30

C1 -0.01 F

ceramic disc capacitor 50

Vdc
R1

-39K;

1/4

-watt resistor

TRIGGER CIRCUIT PARTS LIST

T1

ALTERNATE CAPACITOR BANK

BOARD
a

SLAVE TRIGGER PARTS LIST

SC1-National Semiconductors Ltd.
NSL- 701 -3, 3- element, series -connected silicon cell

plug

OFF

110 -120 VAC

R7- 2- megohm

1 -watt resistor
-watt resistor
C5 -.25F Mylar capacitor 400 Vdc
Flash tube socket, standard 4 pin radio
socket
Flash camera sync socket, standard ac
socket
Flashtube DXKemlite Laboratories,
1819 W. Grand Ave., Chicago, Ill.

R5,
R6

-3-megohm

5-

FLASHTUBE
SOCKET

60622

R6
3 MEG

T1

TRIGGER

PC

BOARD

1-

BARE -BULB PHOTOFLASH CIRCUIT. Circuit a shows the series capacitor bank which
provides a 200 watt- second output. Circuit b shows the alternate capacitor bank which provides a 100 watt-second output. With the optional addition of capacitors C5 and C6, circuit
b provides 200 watt- seconds. An optional switch wired between the positive terminals of the
capacitors in circuit b will also provide multiple power output ratings. Circuit c is the trigger
circuit.
Fig.

larger

SCR -General Electric C106B3 SCR Ac

C3-C6-525F
450V

C3

POWER & CAPACITOR BANK

ON

Computer grade capacitor circuit

The circuit hoard illustrated in Fig.
2 can be used for computer -grade ca-

_1

5W

T1

S1

II

3900F
250V

PC

C5,,,..

C3

IL

I
C6,--rs

Fi

power output and requires

canister housing.

T2

T2

osz

A15B

D2

puter -grade capacitors to hold up under

rapid discharge cycling and of the
higher leakage rate common with this
type of capacitor. The alternate, par-

allel circuit employs the standard

photoflash capacitors for maximum

200 WATT- SECOND SERIES

CAPACITOR POWER PARTS LIST
S1 -Dpdt switch -rocker or toggle type,
Allied Electronics No. 700 -5110 or
equal
F1 -11/4 amp. Slow -Blow
D1, D2, D3- General Electric A15B or
equal 1A 200V silicon rectifier
R1-400 -ohm, 10 -watt resistor
R2, R3-30K, 5 -watt resistor
C1 -180 F /200 Vdc Mallory
No. CG181T200A1
C2 -180 F /350 Vdc Mallory
No. CG181T35OB1
C3, C4 -3900 F /250 Vdc Mallory
No. CGS393T250FH1

Ac line cord and plastic strain relief.

-

C2

PARALLEL CAPACITOR
POWER PARTS LIST

-Dpdt switch, rocker or toggle type,

Allied Electronics No. 700 -5110
F1 -11/4 amp. Slow -Blow
D1, D2, D3- Silicon rectifier GE type
A15B or equal
R1 -400 ohm, 10 watt resistor
C1 -180 F /200 Vdc Mallory
S1

4 -5/8"
2 -7/8"

11/16"
I

L1

3/- 8"

T2

5/16"

T1

L2

15/32"

No. GC181T200A1
C2 -180 F /350 Vdc Mallory
No. GC181T350B1
C3, C4, C5, C6-525 F /450 Vdc Mallory type FF45052 or equal

7/16"
13/32"

D3

1"
16

"

16

2
6

32

t-6

-f
19"
32

15/16"

FIG. 2 -FOIL PATTERN for series capacitor bank which provides 200 watt- second output.
This foil pattern is also used for the parallel capacitor bank, having an output of 100 watt seconds, with a jumper connected between J1 and J2 and other modifications (see text).

34

www.americanradiohistory.com

pacitors in series or standard photoflash capacitors in parallel with minor

changes. The series circuit employs
Mallory 3900 -F. computer-grade capacitors. This amount of capacitance
will produce a 200 watt -second output
to the flash tube. Resistors R2 and R3
serve to equalize the voltage across
the capacitor discharge bank, C3 and
C4. To produce the charging dc voltage

for C3 and C4, capacitors Cl and C2,

in conjunction with the silicon diodes
D1, D2, and D3, form a voltage tripler circuit to transform 117 volts
ac into 450 volts dc. Fuse FI is rated
at
ampere and must he of the SlowBlow type due to the greater current
drain during the initial forming of
computer -grade capacitors. Likewise,
the current limiting resistor R1 is rated
at 10 watts and must be mounted no
less than !/a inch above the circuit
board to properly radiate the heat generated in the initial forming operation.
A jumper is indicated at J1 and J2
of Fig. 2. The jumper is only used
when modifying the circuit board for
standard photoflash capacitors and is
not required for series capacitors. The
dimensions indicated on Fig. 2 are to
locate drill centers for components
and capacitors. All electrolytic capacitor terminal holes are 1/4 inch in diameter. When mounting the capacitors,
he sure that the number 10 washer is
between the copper circuit and the
capacitor terminal with the mounting
screw inserted through the 1/4-inch
hole from the component side of the
circuit board. Be sure the correct polarity is observed in mounting the
capacitors.

C4

O
C6

1"

~2~~4

FIG. 3--FOIL PATTERN for parallel capacitor bank wh ch provides 200 watt- seccnc output
(connect jumper between J1 and J2). With modifications, the foil pattern is also used for the
multiple power output flash (see text).

TS1

TS2

Parallel standard
photoflash capacitors
Only minor modifications are needed
to convert the circuit board in Fig. 2
to the parallel- connected standard
photoflash capacitor bank. The 1050
F capacitance (525)2F + 525F) will
produce an output of 100 watt- seconds
or, if you prefer, you can use the
larger circuit board in Fig. 3 with four
standard photoflash capacitors. This
will produce a 200 watt- second output
similar to the computer -grade series
capacitor circuit. In parallel use, the
circuit board in Fig. 2 does not require
R2 and R3. The 10 -watt resistor RI
must now be connected between the
cathode of D3 and the heavy foil
strip running across the top of the
hoard. (Use the holes provided for R3
in the series-capacitor circuit.) Capacitor C4 must be reversed in polarity
so that the positive terminals of C3
and C4 are attached to the plus bus
circuit. Now connect a number 18
wire between jumper terminals Jl and
J2. Trigger terminal T2 cannot be
used as shown. Move it to the positive
terminal bus at point R2. No change
is made to the voltage -tripler circuit
or its associated capacitors or diodes.
The four -capacitor parallel circuit
(Fig. -b, using the circuit board in
Fig. 3) can be modified to provide
selectable light output. For a choice
of either 100- or 200 -watt- second output, connect a single -pole, heavy -duty
1

I0

3"

J2

FIG.

TRIGGER

-FOIL

PATTERN for the

trigger :ircuit.

PC

BOARD

1"
34

toggle or rocker switch instead of the

jumper between points J1 and J2 in
Fig. 3. For a choice of 50, 100, 150
or 200 watt -seconds, modify the circuit board by removing the copper foil
paths between the positive terminals
of C3 and C5 and C4 and C6. Install
a heavy -duty single -pole, 4- position

progressive- shorting switch on the

housing top. Connect the four terminals to the positive terminals on C3C6 and the arm to point T2.

WARNING: ONLY POWER-CAPACITOR BANK (Fig. -b) CAN BE

MODIFIED WITH OPTIONAL
POWER SELECTION SWITCH.
UNDER NO CIRCUMSTANCES
SHOULD A POWER SELECTION
SWITCH BE ATTEMPTED ON
FIG.
-a SERIES-CONNECTED
COMPUTER -GRADE CAPACI1

TOR CIRCUIT. PLACING ONLY

ONE CAPACITOR ACROSS 450
VOLTS DC WILL PRODUCE A
DANGEROUS OVERLOAD OUTPUT AND CREATE A ?OTENTIAL EXPLOSIVE COND-TION
IN THE CAPACITOR.
Trigger circuit board
The trigger circuit shown in Fig. -c
is simple with only 4 components. The
PC board for the trigger circuit is
shown in Fig. 4. Since the ilashtube
socket is on the component side of the
circuit board, some minor difficulty
may be encountered in connecting the
flash tube socket to the circuit connections 1, 2, 3, and 4. All that is necessary
to make the proper connection!. is to
attach number 16 solid wires to the 4
tube socket pins and insert the other
end of the wires in the corresponding
1

35
www.americanradiohistory.com

print hoard contact holes and solder.

Firm mechanical connections must be
made to the tube socket pins to prevent solder heat from breaking a
solder-only connection.
To mount the trigger board to the
housing's top, attach 4 stand -off terminals to top and solder stand -off pins
through 4 corner holes of the trigger
circuit board. TS1 and TS2 connect
to the camera sync socket which consists of a standard ac connector, with
either number 16 or 18 flexible, stranded wire. The camera sync socket is
mounted on the housing's top and can
be either a push-in, snap -lock, or
screw -mounted socket. This location
for the sync socket minimizes the
number of connections between trigger
circuit board and the power- capacitor
bank and places the sync socket in the
most advantageous position for use
with an optical slave trigger.

three 0.1 x 0.2 in. silicon chips connected in series to provide sufficient
voltage output to trigger the SCR when
struck by the light from the master
flashgun. The NSL -701 -3 can be purchased for $6.00 from National Semiconductors Ltd., 331 Cornelia Street,
Plattsburgh, NY 12901.
(The NSL -701 -3 is sold as an assembly of bare silicon chips. These
are very fragile and easily damaged.
If you wish, you can purchase a comTO

117 VAC

CIRCUIT
BOARD

SHUNT

CAPACITOR BANK CIRCUIT board can be

seen from component side of board.

plete optical trigger-ready to plug

into the flashgun from most photo
equipment supply houses for approximately $15.00. The device is the Wein
Micro Slave. Editor)

Power input connections

Ordinarily, one would expect the
power switch discussions to he along
with the 117 -volt ac tripler circuit.

However, because there is a potential

shock hazard associated with the ac
power switch, it is described separately. Only a double -pole double throw switch should be used in the ac
power line. The ac line must be connected to either the two top or two
bottom terminals of the switch with
the power- capacitor bank connected
to the center terminals of the switch
and a jumper connected to the unused
terminals. This connection, shown in
Figs. -a and 5, prevents voltage feedback through the switch to the ac plug
terminals and eliminates a potential
shock hazard. It also provides a capacitor discharge shunt when the switch
is in the OFF position, to remove dangerous stored capacitor voltages.

Final assembly
FIG.

5-AC

NSL -70I

FIG.
CUIT.

Upon completion of the power capacitor bank and trigger circuit

SCR

cl

sci

Optical slave trigger

The most valuable accessory to electronic photoflash photography is the
optical slave trigger for your photoflash (Fig. 6). It triggers the photoflash with the light from your camera
mounted photoflash and eliminates the
use of two sync cables. Figure 7 illustrates how the four components are
assembled on the prongs of an ordinary ac plug and encapsulated in a
clear plastic or epoxy resin. The General Electric C106B3 SCR is specified
not only for the electrical specifications but for the anode terminal position opposite the gate and cathode
terminals. This is most convenient for
mounting the SCR on the prongs of
the sync plug.
The light- sensitive device is a National Semiconductors Ltd. type NSL 701-3 silicon photodiode. It consists of

POWER SWITCH wiring.

C106B3

01

6- OPTICAL

SLAVE

AC PLUG
TRIGGER CIR-

REAR VIEW OF PHOTOFLASH unit mounted

on tripod shows power cord and ac switch.

7-

OPTICAL SLAVE TRIGGER component placement diagram.

FIG.

36
www.americanradiohistory.com

hoards, the final mounting of components in the plastic housing is begun.

Figure 8 shows the side view of the
component mounting inside the can istor housing. The ac power switch is
mounted on the bottom plate of the
housing with the 117 volt ac line connected to the end terminals on the
switch and a shorting jumper connected across the opposite end terminals (see Fig. 5). Connect a 10 -inch
section of ac cord from the two center
terminals of the switch and run it
towards the top of the housing. Next,
insert the power- capacitor bank circuit
board to locate the tripod mounting
position. The correct position for the
tripod mount is slightly below the
bottom of capacitor Cl, with enough
space below Cl for adequate back plate support. The tripod socket can

N1

surplus radio transmitter or antenna

tuning unit. Diagram a shows how
to connect it. (I have a hunch that
the burners on electric ranges have
a similar switch so you might lok
into this.)
If you can't find a progressive shortirg switch, you can make an
equivalent from by wiring a 4 -pole,
4- position rotary switch as in diagram b. It should have ceramic
wafers and contacts rated at at least
5 amps at 350 volts dc.
The DX -5 flash tube is rated at
150 watt- seconds maximum, However, the author assures us that he
has not noticed any shortening of
the tube life due to its operation at
200 watt- seconds. Furthermore, this
tube is used in several commercial
200 watt- second flash guns.

If you select the variable- output

circuit for your flashgun, you'll find

progressive- shorting switch almost impossible to obtain because

it appears that they're now being
made only on special order.
Do not be misled by the terms
"shorting" and "non- shorting" in
a

switch catalogs. A shorting -type

switch has its arm or wiper arranged
so it establishes a new contact before breaking the old. In a non shorting switch, the wiper breaks
contact with one terminal before it
makes contact with the adjacent
one.
A progressive- shorting switch has
long wiper that progressively connects or shorts the fixed terminals
until all are tied together. Your best
chance at a suitable switch of this
type is to salvage one from a
a

TT T.
50

T2

loo

)F

150
10---0

200
3

)1+
o

-Editor

FLASH TUBE
CAPACITOR BANK
CIRCUIT BOARD

METAL
SHIELD

CAMERA SYNC
SOCKET

TRIGGER
CIRCUIT
BOARD

WATT

)1+

ECONDS

STAND-OFF

T1

be made from a 1 -inch circle or square

Cl

C3

FIG.

8- COMPONENT PLACEMENT

C4

AC POWER SWITCH

DIAGRAM for the barebulb photoflash unit.

plate of aluminum or brass, ?'i inch

thick and with a 1/4-20 three ded hole
in the center point of the plate. Or,
if you prefer, a tripod socket may be
purchased from your local 2amera
store or a quick- release tripod base is
available from Edmund Scientific Co.,
101 East Gloucester Pike, Ban ington,
N.J. under catalog number 40941.
With the tripod socket installed, wrap
the capacitor bank, below the print
hoard, with plastic film or acetate
sheet and tape securely. This wrapping
offers additional electrical shielding
and will contain capacitor electrolyte
should a capacitor rupture Lit- any
reason.
Insert the power -capacitor circuit
into housing and firmly seat the pc
board to housing sides. A small piece
of tape is sufficient to secure :h.: entire
assembly if the pc board has been
accurately contoured to the housing's
interior dimensions. Attach the trigger
circuit connections and insert the top
of the housing onto the housin. body.
However, do not secure the tole to the
body at this point. Insert the lash tube
in the flash tube socket.
(continued on p2ge 80)

37
www.americanradiohistory.com

Whya Sylvania home training program may be

your best investment

for a rewarding
career in electronics

www.americanradiohistory.com

LEADER IN ELECTRONICS
TRAINING

Over the years, Sylvania Resident

Schools have trained thousands of
men and women for key positions in
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Remember, this training is designed
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with one purpose in mind
you the background you need to land
the electronics job you really want!

AUTOTEXT TEACHES YOU

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back if you take, and fail to pass, the

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help you over any "rough spots" that

Sylvania Technical Systems.

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SYLUANW TECHNICAL

CASSETTE SYSTEM

This innovative learning -by- hearing

approach is a special option that adds
an extra dimension to AUTOTEXT. It's
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cassette tapes, you'll have an instructor guiding you through your
AUTOTEXT lessons. Explaining the
material as you read it. Going over
schematics with you, reinforcing the
basic electricity and electronics study
materials with you. Everything you
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towards a highly regarded position as
all in an
an electronics technician
easy -to- understand, conversational

HANDS -ON TRAINING

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To give Practical application to your

studies, a variety of valuable kits are
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TV set, and a color TV set. You also

construct an oscilloscope which

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909 Third Avenue
New York, N.Y. 10022

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method of home training that can help
you learn the basics of electronics
quickly and easily.

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AGREEMENT

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41

www.americanradiohistory.com

THE LOW COST MINI -COMPUTER IS A

reality today. Together with time -sharing systems, they are performing an
increasing number of tasks in all types
of applications.
However, the relatively high cost of
terminals has slowed both the acceptance and the use of the computer in
small businesses, homes, and schools.
The MITS Comter 256 (CT256) corn puter terminal described here can be
built for less than 1/2 the cost of most
terminals and offers many unusual
features not found in terminals costing several times as much.
The terminals important features
include:
A built in acoustic coupler making
computer connection simpler and saving added cost.
An auto -transmit that allows transmitting data or program material to
the computer from memory, line by
line.
Complete cursor control by software
as well as by manual control via the
keyboard.
A tape recorder input 'output jack
to enable taping of frequency shift
keyed (FSK) tones during telephone
connection to a computer. This gives
virtually unlimited memory capability.
Almost any type of tape recorder may
be used.
A 32-character Burroughs display
with a soft orange, highly legible
readout.
Standard ASCII encoded keyboard
with TTY -33 format.
Internal memory capability of 256
characters per page and up to 4 pages
of memory.
Automatic page cha ige at the end

-10
-12

AT
AT
AT
AT

First Computer
of each page for a total of 1024 character storage for a 4 -page unit.
Flexible power requirements. Operable from line voltage of 100 to 130
volts or 200 to 260 volts.
A 25 pin input /output accessory
jack for hardwire computer connection
and add -on accessories.

Yr*RAI

1A

This is a special report

terminal in kit form. It
a computer directly or via

Data flow in the terminal

The block diagram of the Comter

256 (Fig. 1) represents considerable
digital circuitry (91 logic IC's in a 4page unit). The data path starts at the
keyboard. When a character key is depressed, the charcter is encoded into
a 7 -bit binary code and is sent in parallel form on 7 lines to the UART

where the tones are amplified, filtered

and demodulated back into serial binary coding.
From the demodulator, the serial
data goes to the UART and is converted to parallel form where it waits
to be loaded into memory. When a
data available signal from the UART
coincides with the 32nd character display time for the self -scan (right hand
end of display), the first 6 bits of the
character are entered into memory
(the seventh bit is not used in the CT
256 memory) and the data position is
automatically moved one position to
the left.
The self -scan display is connected
to the memory so that as a character
is entered into memory it is simultaneously displayed along with the
other characters in memory. This process is repeated for every character

(Universal Asyncronous Receiver Transmitter-a 40 -pin MOS chip)

which converts the character data to
serial information. The serial data is
sent to the FSK modulator which converts a binary I to 1270 Hz and a binary O to 1070 Hz.
These tones are transmitted from
the acoustic coupler to the computer,
via the telephone lines. The computer
processes the data and returns it back
over the telephone wires to the terminal at a different frequency (binary
= 2225 Hz, binary 0 = 2025 Hz)
The data is fed to the acoustic coupler
1

FSK

FSK

TAPE

MODULATOR

DEMODULATOR

INPUT
OUTPUT

1270Hz
1070Hz

1A

300mA
180mA

- MARK
- SPACE

2225Hz
2025Hz

MARK

- SPACE

FREQUENCY

BAUD RATE X16

UART & RECEIVE

DIVIDERS &
BAUD RATE
TIME BASE

DECODING
B1 -B7

B1 -B7

PARALLEL

PARALLEL

KEYBOARD /TRANSMIT
LOGIC & SWITCH

15 kHz

READ /WRITE
CONTROL

CLEAR
LOGIC

CURSOR

PARALLEL
DATA IN
R/W

PAGE SELECT

RAM POWER
SWITCHING

32 BIT
DISPLAY
COUNTER

CONTROL

MEMORY

X& Y
ADDRESS
COUNTERS

PI
P2

UPDATE

P3

RESET

P4

DDRESS
B1

1-

G.
COMTER 256 COMPUTER TERMINAL block diagram showing data flow. Data flow
starts at the keyboard, which is shown at the left side of the diagram.
F

2 -MHz
CLOCK

RS 232
INPUT /OUTPUT

SERIAL
DATA

KEYBOARD

Rumild

ACOUSTIC COUPLER

POWER SUPPLY

+260 AT 25mA
+5
+5

EXCLUSIVE!

42

www.americanradiohistory.com

SELF
SCAN

DISPLAY

-B6 PARALLEL DATA

15

kHz

Terminal
From A Kit

I
m.s

on a 4 -page computer
can be connected to

111r

telephone lines.
by THOMAS W. DURSTON
transmitted from the keyboard, plus
the computer can also transmit its own
characters to the terminal as the software requires.

i i

i.

How it works

The most important single circuit in

the CT256 is the clock oscillator. It is
a 2 -MHz crystal oscillator that provides the time base for the logic, and
is also used in the modulator of the
acoustic coupler to provide the FSK
tones. A crystal oscillator was chosen
for its stability. The 2 -MHz clock is
divided down to provide 1 MHz, 62.5
kHz, and 15.625 kHz for logic time
base. It is also used to determine baud
rate (data transmission rate) for the
UART. The baud -rate switch selects
either 1760 Hz (110 baud X1o) or
4800 Hz (300 baud X16) for the
UART clock by setting a programmable counter to divide the 2 -MHz
clock by 1136 or 416 respectively. The
modulator in the acoustic coupler
works in a similar manner. Instead of
setting a switch to set a programmable
counter to divide by different rates, it
uses the binary logic 1 or 0 of the data
to derive the two divide rates.
Starting with the data path, the keyboard encodes the character by feeding a 15 -kHz signal to a 4 -bit binary
counter that is connected to a 4 -to -16
line decoder. The character keys are
connected to the 16 lines according to
the first 4 bits determined by the
ASCII code. When a key switch is
closed, and the line it's connected to
is strobed, the 4 -bit counter is halted.
The 4 -bit count where the counter
stopped is the first 4 bits of the 7 -bit
ASCII code and the other 3 bits are
encoded by a series of logic gates.
After a 30-ms debounce period, a
load signal is sent to the UART, where
the parallel 7 -bit character code is entered into registers and transmitted out
serially at the selected baud rate. The
serial data is sent to the modulator
where it is converted into audio fre-

is fed
into a speaker which transmits the
FSK audio to the transmitter of the
telephone handset.
When the computer returns the data
or originates its own, it is received as
a 2225 -Hz or 2025 -Hz tone. The signal is picked up by a ceramic microphone adjacent to the receiver in the
telephone handset, and is amplified
and converted to a low- impedance output by a JFET -NPN transistor circuit.
This low- impedance circuit feeds the
tape cutput and a two -stage op -amp
active filter.
The two -stage filter removes noise
and irterference and provides a gain
of about 400. The filter output feeds a
carrier detector circuit that turns on
the carrier LED, enables the transmit
circuit, and enables the FSK demodulator which consists of an XR210 IC
phase locked loop. The output of the
op -amp filter also feeds the XR210
and tie signal is demodulated into
serial binary form. This serial binary
data is fed into the UART and is
sampled at the set baud rate. If the
serial data is valid, it is converted into
a 7 -bit parallel format corresponding
to the ASCII code for the character
received.
The UART also indicates that it has
new data available. Meanwhile, the
receive decoding determines if the new
7 -bit character is a display character
or a control character. If it is a display
character, it is allowed to be entered

'

'

.,

11

i
/

1
r

quencin as described before and

into memory, if it is a control character (bell signal, cursor con p-1 char;
see table of control characters: the receive decoder inhibits memory loading
and initiates the necessary operation.
Memory operation
Probably the most involved crcuitry
in the CT256 centers arounc t -e 5 -bit
(32 count) display counter acid 4 -bit
(16 count) X -Y memory address
counters. The X-Y memor i address
nt) upcounters are both 4 -bit (16
down, presettable counters, making a
total combination of 256 addresses
(16X by 16Y). For referen.e sake,
the Y addresses are called li es and
X addresses are called characeer positions (see Fig. 2 & 3). The saart of the
page is called "home" (see Fig. 4)
and has address 0, 0 (line y'i, position
0). When the black "H" key home)
is depressed, it homes the daft to the
cursor position (right hand n.I of display-32nd character) and r, cults in
the X-Y address counters bein: at Ql, 0
during the 32nd character disp'i ay time.
The cursor position is very important because it is during thi 32nd character display time that; n :w data
is entered into memory, data i> shifted
right or left in the display. data is
homed, memory is cleared, and many
other timing chains are based.

cr

43
www.americanradiohistory.com

bits of ASCII code to locate a particular address in memory and display it

in the cursor position. The first character received after the address function is initiated, selects the line number
(1 -16) by setting the Y address counter
equal to the first 4 bits of that charac-

CHARACTER (6 BITS)

ASC11CHACODE

ENT
HERE

HOME

CHARACTER POSITION

01

2 3 4

5 6

7 8

9 J K

L M

N?

Y ADDRESS

(LINE POSITION)

3
4
5

6
7

8
9
J

FIG.

2-

RAM

X ADDRESS
(CHARACTER
POSITION)

M
RAM 6
ADDRESS 8J LOCATES
CHARACTER IN THE
CUP`
?F SELFSCAN DISPLAY
TH

MEMORY FORMAT. The 6 -bit character is entered into memory in ASCII code. The
memory location is selected in accordance with the respective position on the page (line and

character position.)

At the time when the UART indicates new data available and the 32nd character display time starts, the read/
write logic generates a write pulse for
the memory. The first 6 bits of data at
the output of the UART are then
written into 6 RAMs (Random Access
Memory) at that address. The write
pulse also goes to the cursor control
logic, where, upon completion of the
write pulse, the X-address is incremented one position, shifting the data
one position to the left on the display.
The write pulse also triggers a circuit
that resets the data available line from
the UART.
The clear circuit, activated by either
pressing the black "C" key or receiving a control "L ", enters the ASCII
code for a blank into all 256 positions of memory for that page. It
works by holding the write circuit on
and forcing the data input lines to the
memory to coding for a blank. This
only takes place during the 32nd character display time during which
it "homes" the X & Y counters and
advances the X-counter 256 positions
(one complete page) at a 1 -MHz rate.
The auto transmit circuit works by
depressing the black "T" key which
activates logic that switches the transmit data lines from the keyboard to
the data output lines from the memory.
Whatever character is in the cursor
position of the display is transmitted
out to the computer. As that character
is received back, it is re- written into
the same position in memory, the data
is shifted left one position and the next
character in memory is transmitted.

'

3-

MEMORY FORMAT shows the page

position and character location respectively.
Address 0, 0 is the "home" position on the
FIG.

page.
LINE

POSITION 0

..LINE

DATA
LEFT
1

1[ 1[

POSITION

16

CHARACTERS

[[l1[111111111111111
LINE 0 POSITION

DATA
RIGHT

SELF SCAC.

CUPS(._P

DISPLAY

DOME POSITION
PAGE

FIG. 4 -PAGE FORMAT shows how the page is displayed on the Self Scan display. Each line
of the page is 16 characters long and the page is displayed one line at a time.

Since the memory only stores the first

6 bits of the 7 -bit ASCII code, the 7th
bit must be derived by logic gating.
This is one reason why the CT256

cannot auto -transmit control characters.

The 7th bit cannot be derived for

control characters, and since the memory does not receive and store them
anyway, they have to be transmitted
manually via the keyboard. To allow
entry of control characters such as
carriage return, the detection of the @
symbol will cause auto -transmit to stop
and the desired character may be manually transmitted. The @ symbol is
detected in the cursor position and
auto transmit cannot take place unless
it is shifted out by manually entering
a new character.
The address function is initiated by
pressing the black "A" key or by receiving a control "O ". It sets up the
receiving decoding to accept the next
two characters and use their first four-

www.americanradiohistory.com

ter's ASCII code. The second character

received selects the position in the line
(1 -16) by setting the X address counter
equal to the first 4 bits of that character's ASCII code. These two characters
are used only for address location and
are not loaded into memory. For Y
(line) and X (position) identification
see Fig. 3.

Page circuitry
The page control circuit for a multi
page unit consists of two circuits for
each page. The first set of circuits enables each set of 6 RAM's, making
them active for the page selected; the
second set of circuits reduces power
to the unused pages to standby levels,
reducing current drain by 75 %.
The operation of the page control
circuit is determined by the setting of
the PAGE switch. In MANUAL, the page
can only be changed by depressing the
black "P" key. Pressing the black "P"
(continued on page 91)

ta&IR
ffluItiu1?ir
Ruuidup
The digital multimeter has finally moved out of the laboratory and
onto the service bench. Here's a rundown on those that sell for $300 or less.
by ROBERT F. SCOTT
TECHNICAL EDITOR

FOR YEARS THE MULTIMETER HAS BEEN

the principal -and sometimes the only

instrument used by the service
technician for voltage, current and resistance measurements. Many old timers have an almost continuous
squint acquired from peering at a
meter and trying to read the voltage
indicated by a pointer that has banged
against its pins once- too -many times.
Digital meters -presenting the metered quantities in large easy -to -read
numbers -have been used in laboratories, industrial plants, etc. for years
but have just recently been developed
to the point that they are priced within
the reach of electronic service technicians and many experimenters.
The digital multimeter, often called
a dmm or dvm, offers many advantages to the busy service technician.
For example, in some dmm's, range

-test

selection, polarity indication and decimal point placement are performed

automatically. The indications are often
large enough to be easily read from
up to 20 feet away. Parallex does not
exist so it cannot affect reading accuracy. The accuracy of the instrument
is much greater than a typical analog
vom or vtvm.
There are quite a few new dmm's
in the $300 and under class that will
appeal to the service technician and
advanced experimenter. We are going
to discuss the features and operating
principles of the dmm and present the
pertinent specifications of the instruments you should consider before
making your selection.
How the dmm works

The analog instrument takes the

meterec quantity--voltage, current or

S2 /S3

VOLTAGE
ATTENUATOR

>--

>-

INPUT
SELECTOR
SWITCH

odCURRENT

SHUNTS

OHMS

CIRCUIT

AC

AC -DC

CONVERTER

Dc/st O
AC

DC

AMPL

DC/S2

RAMP
GENERATOR
COMPARATOR
(A /D CONVERTER)

0.1

DIGIT DRIVERS
l

SEGMENT
DRIVERS

DISPLAY

BATTERY
DISPLAY MULTIPLEX
RATE

to- digital converter whose cutput

drives a digital display or readout.
Compare the block diagram )f the
Ballantine model 3/24 dmm Fig. 1)
with that of your Simpson 260, Triplett 630 or similar instrument and

you'll see the resemblance. Tie dmm

is basically a dc instrument with a
scaled -down portion of the input voltage applied to the display through the
analog -digital (A -D) converter. Resistance is measured by passing ,t constant current through the tin mown
resistor and measuring the voltage
drop across it. Current is mete ed by
measuring the voltage drop across a
current shunt. When measuring ac
voltage or current, a rectifier is inserted
between the input attenuator and the
A -D converter.
The A -D converter is the in erface
between the analog dc input and the
digital display device. There are a
number of different ways of converting an analog dc voltage to a digital
value. Among these are: vollal;e-con-

trolled oscillator, single -ramp and

LSI

CLOCK
OSCILLATOR

resistance-and converts it into z, voltage that is read on the meter in the

proper values and terms. A precision
voltage divider attenuates the tes: voltage so it is within the basic v Dltage
range of the meter movement The
dmm is similar except that the m wing coil meter is replaced by an a ialog-

POWER
SUPPLY

ii
+10v +5V

19V

14V
FIG. 1 -BLOCK DIAGRAM OF BALLANTINE MODEL 3/24 digital multimeter. Note the basic
similarities between this and an analog multimeter.
0

www.americanradiohistory.com

double -ramp integration, charge balancing and successive approximation.

All have advantages and disadvantages
that affect accuracy, ,resolution, and
the rate at which the-display can follow or track a changing input signal.
The study of A -D converters as applied to dmm's is quite interesti g; but
is beyond the scope of this article. If
enough of you are interested. we'll
cover A -D converters in a fut ire issue.
Displays
The three types of display:.

corn-

mon use are LED's in both 5 X 7 dot

matrix arrays and seven-segment arrangements; liquid crystals in both
transmissive and reflective types and
gas-discharge tubes such as the Nixie.
Each type has its advantages and disadvantages.
Gas- discharge tubes generally offer
brighter and larger digits that can be
read from greater distances. However,
they require a relatively high excitation voltage and their current drain is
high enough to restrict their use to
line -operated bench -type instruments.
LED's are the most common type of
display. They are easy to read in either
format; are high -efficiency devices that
operate from approximately 1.5 volt
and draw about 25 mA per segment.
When the display is strobed, the average power is low and long life can be
expected from high -quality dry cells.
There are reports that some bench
technicians complain of eye strain and
fatigue after long hours of reading
LED and gas -discharge displays. Too,
both types tend to wash -out when
viewed in bright sunlight.
Liquid crystals are the new -comer
to the display field and seem to be the
ideal in terms of power consumption.
A liquid -crystal display draws only
microwatts while an equivalent LED
display will draw many milliwatts.
This type of display is made in
both
transmissive and reflective
types. The former must be backlighted which compromises the power
TWENTY TWO RANGES, four each for
dc and ac volts and current and six for
resistance are included on the Data
Precision model 134. Its 31/2- digit, 7segment gas- discharge display incorporates 200% over -range and has a
reading rate of approximately 1 per second. Voltages up to 1.5 kV rms; current

*5;16
L

saving gained through its use. The reflective-type display can be used in
areas where high ambient light and
widest angular visibility are not needed.

Battery operation
Most dmm's are line-operated with
built -in batteries. Some have throwaway dry cells and others have rechargeable batteries, either installed or
in optional battery packs. If you want
a battery -only instrument, be sure that
the batteries will last long enough for
a couple of days use.
LINE -OPERATED VERSION of the model
is Data Technology's model 20.
Ranges, functions and specifications are
the same as in the hand -held model 21.
21

The case is 13/4 inches high, 21/2

inches wide and 31/4 inches deep. Its
carrying handle also serves as an adjustable tilt stand. $187.

Options include single and side-by -side

rack mounts, carrying case, high -voltage
probe; 100 -, 115- and 230 -volts ac line
operation and IC sockets for quick component replacement, 2.5 x 6.25 x 9 in.,
2.3 lbs. $269.

within the reach of hams and beginning

electronics experimenters while meeting
the specifications required for many operations on the radio /TV service bench.
Its ranges are: 2, 20, 200 and 1000
Vdc; 2, 20, 200 and 700 Vrms (25 Hz to
10 kHz); 2, 20, 200 and 2000 mA dc and
ac; 200, 2000, 200,000 ohms and 2 megs.
Overrange is 25% on all ranges-within
maximum limits. Resolution on the low-

Optional isolation probe has switch able 100K isolating resistor. High -voltage probe extends range to 30 kV. 31/2
X 7V/8 X 87/8 in. 41/4 lbs. $189.

PLUG -IN BOARDS, IC'S AND readouts for easy replacement are features
of the DigiTec model 2110 and 2120.
Internal rechargeable batteries facilitate
operation independent of power lines. A
built-in automatic charger keeps the
batteries charged as long as the dmm
is connected to the power line.
Dc voltage ranges extend from 199.9
mV to 1000 volts full scale with basic
accuracy of 0.1% of the reading. Ac
voltage can be measured from 1.999 to
500 volts (750 volts on the 2120) with

FOUR RANGES and cold- cathode readouts and indicators are used in the
Heathkit IM -1202 portable digital multi meter. This 21 -digit instrument is well

to 2 amps and resistance to 20 megs

can be read. At 100% overrange, the
reading is 1999. Readings above 1999
are indicated by the lighted "1" and
selected decimal point. The other three
digits are blanked.
The least significant digits are 1, 10,
and 100 mV and 1V on the voltage
ranges; 1, 10, 100 A and 1 mA on current; and 0.1, 1, 10, 100, 1K and 10K in
the resistance mode.

WORLD'S SMALLEST is the claim made

for the Non -Linear Systems model LM-4,
a full 4-digit instrument with full -scale
count of 10,000 on 0.31 -in. red LED display elements. It measures ac and dc
volts from 100 V to 500 V and resistances from 0.1 ohm to 10 megohms and
operates from the 117-volt line.

est ranges is 10 mV, 10 A and 1 ohm.

Accuracy (full scale 1 digit): dc volts
1 %; dc and ac current and ac volts
1.5 %; ohms 2 %.
Input impedance is 1 megohm on all
voltage ranges. Power requirements
110 -130 or 220 -260 Vac, 50/60 Hz. 73/4
X5/16 X 31/e in., 21/2 lbs. $79.95.

46

www.americanradiohistory.com

accuracy of 0.5% of the reading. Basic

accuracy of 0.5% of the reading is
available on five resistance ranges extending from 199.9 ohms to 19.99 megs.
A zero control permits nulling test -lead
resistance.
Functions are selected by pushbuttons
while ranges are changed with a rotary
switch that includes a BAIT CHK position. Input impedance is 10 megs on
dcV; 1 meg shunted by 10 pF on acV.
The 31 -digit display uses 0.3 -in. high
LED numeric indicators. Overrange
blanks all numerals except the over range "1", polarity sign and decimal
point.
Gulton R -200 batteries operate the
model 2110 a minimum of 8 hours and
the 2120 5 hours in continuous operation. Recharging takes 16 hours after
full discharge.
The 2120 (not shown) has all the features of the 2110 plus five ac and dc
current ranges extending in decades
from 1.999 p.A to 1.999 A.
Power requirements 115/230 V, 50400 Hz; 2.5 W for the 2110 and 5 W for
the 2120. Size 2.43 X 7.25 X 7.95 in.,
2 lbs. less batteries. Model 2110 $219,
2120 $275.

AUTOMATICALLY POSITIONED decimal point, 100% overrange capability

and fool -proof out -of -range indications
are features of the B & K Precision
model 281. On this 21/4-digit instrument,
out -of -range is indicated when the first
digit remains on while the second and
third digits are off.
Ac and dc voltages are measured on
100 mV, 1.00, 10.0, 100V and 1.00 kV
ranges. Accuracy is .1% of reading

1 digit on dc and 1.5% of reading

1 digit on acV. Current measurements
(ac and dc) are in 100 A, 1.00, 10.0
ana 100 mA and 1.00 amp ranges with

accuracy of 1.5% of reading 1 digit.

Frequency response is 20 Hz to 1 kHz.
Seven decade resistance ranges (10
ohms to 10.0 megohms) provide accurary 2% of range to 1 megohm and
3% of range on 10 megohms. The instrument provides 100% overrange on
all functions.
The 281 operates from 117 Vac, 15 W.
31/2

Reading specifications
The '/2 digit: Dmm's are generally
specified by the number of digits (numeral indicators) in the display. Each
digit is capable of displaying any numeral from 0 to 9. A 3 -digit instrument will have a maximum reading of
999 anc a minimum of .001. If it has
1, 10, 100 and 1000 volt ranges, it
reads maximums of .999, 9.99, 99.9
and 999 volts, respectively.
Each digit added to a display increases circuit complexity and cost proportionately. Manufacturers found that
they could improve the resolution (the
smallest change in the quantity being
NOISE COMPONENTS on the signal being metered are removed t a two-pole
filter before being processed by the
A/ D converter in the Fluke model 8000A.

is a compact 3V2 -digit instrument

featuring pushbutton range and function
selectioi, automatic polarity switching,
a self -locating decimal point and selfzeroing to eliminate offset uncertainties.
The basic dmm is designed around 0.2
and 2.0 Vdc and has twenty six ranges
and six functions.
The 8000A measures ac and dc volt-

It

X 7 X 9 in. 5 lbs. $170.00.

CAPACITANCE READING CAPABILITY

in a hand -held dmm is a unique feature
of the Data Technology model 21. It is
a 3V2 -digit instrument powered by four
internal rechargeable batteries that provide up to several weeks of intermittent
usage. It comes with a plug -in battery
charger that can be specified for 100 -,
115- or 230 -volt operation. Battery
charge life is extended by the use of
PUSH -TO -READ switches.

Voltage ranges are 2, 20, 200, and

1000 volts dc and peak ac with 1 -mV
resolution. Resistance ranges are 2K,
20K, 200K and 2 megohms. Capacitance
is read in four ranges from 2 to 2000 nF
(.002 to 2.0 F) with resolutions of 1, 10,
100 and 1000 pF.
Accuracy on resistance and capacitance is 0.15% of reading +0.05% of
full scale; 0.1% of reading +0.05%
of full scale on dcV and 0.5% or reading
+0.1% of full scale (50 to 500 Hz).
The model 21 slips into a pocket or
into a handy carrying case that clips
onto a belt. It is 6.8 x 3.25 x 1.75 in.
and weighs only 12 oz. $269.

ages from 100 V to 1199 V; current

from 100 mA to 1.99 A; and resistance
from 100 milliohms to 19.99 megs. Dc
voltage and current are measured with
accuracy of 0.1% of reading +1 digit
and 0.3% of reading +1 digit, respectively. On ac (45 Hz to 10 kHz) voltage
accuracy is 0.5% of reading + 2
digits. Current measurements are 1%
of reading +2 digits (except on 2000
mA where frequency is limited to 3
kHz). In the range of 10 kHz to 20 kHz,

measured that will produce a change

in the display reading) of their instruments at little increase in circuit corn plexity or cost by adding a kf- -hand
digit that displays only the ni meral
"1." This "1" is called the hall- digit.
Thus, a 31/2-digit instrument can display 1999.
Overrange is an extension of the
half -digit technology and is a means of

extending the readings beyond what

would be full -scale on an aralhg in-

strument. Most multimete -s have

ranges of 1, 10, 100 and ICOO or

similar decades. Now, suppose teat we
want to measure the precise voltage of
a standard 1.5 -volt dry cell. Using an
analog instrument, we would hive to
use the 10 -volt range and WMi d not
be able to read the voltage `" "I any
degree of accuracy. With a c n n, we
would use the 1 -volt range. T-le applied voltage would be greate- than
the range selected. The instrument
half would sense an over -range;
digit "1" would light and the 'voltage
MN

TRUE PORTABILITY AND LAB precision are claimed for the 41/2-digit Data
Precision model 245. It is about the size
of an Instamatic camera and eden in-

cludes a wrist strap. Voltage, current

and resistance are read on 21 ranges
with 100% overrange. It comes with
carrying case, wrist strap, tes- leads
and a battery module that includes rechargeable batteries, battery charger
and line cord.
When operated on the ac 'lice, the
batteries remain on charge whether the
dmm is turned on or off. When disconnected from the power line for portable
or field use, the batteries last at least
6 hours before recharging is required.
Recharging takes about 12 heurs.
Ranges: Dc volts 1.000 to 1030 with
100 %overrange. Input impedance 10
megs on three highest ranges; over
1000 megs on 1.000 -volt range. On ac,
the ranges are the same as on dc

voltage accuracy is 1% of reading

+2 digits. Resistance accuracy is
0.2% of reading +1 digit on all ranges
except 0.5% of reading +1 digit on
20 -mec range.
Inpu: impedance is 10 megs on dcV
and 10 megs shunted by 100 pF on acV.
Optional probes extend measurement
capabi;ities to 30 kV dc, 200 amps dc
and to 500 MHz on acV.
The Fluke dmm is available in somewhat more expensive options. The
8000A -01 includes an optional rechargeable battery pack providing over 8 hours
of portable operation. The 8000A -02 has
a digital printer output; the -05 features
a 10 -amp current range and the -06 has
low ohms (2 and 20 ohms) ranges.
The 8000A operates from 100 -115
and 230 Vac, 50 -400 Hz, 2 W. 2.52 X

except on the 1 -kV step where over range voltage is limited to 500 volts.
Ac input impedance is 1 rnegohm
shunted by 50 pF or less. Maximum rms
input is 500 V, 30 Hz to 10 kHz, above
10 kHz it decreases linearly to x:00 V at
50 kHz. Settling time (to se'Ue within
0.1% of final reading with fell -scale
input) is 2.5 sec.
Current (ac and dc) 1 mA tc 1 A in
four decade ranges with 100 overrange. Resistance: 1K to 10 megs in five
decade steps. Least significant digit on
lowest range is 1 milliohm. Maximum
open- circuit voltage is 3.5 V.
Operates from 105 -125 -vo is 47-63

8.55 k 9.9 in., 2.75 lbs. $299.

Hz. 51/2 X 13/4 X 31/2 in. 1.3

Its. $295.

47
www.americanradiohistory.com

could be read with three -place accuracy

-1.470 for example
impossibility
with an analog vom.
Accuracy of an analog vom is
usually specified as a percentage of the
full -scale reading-generally 2 to 3 %.
Parallax, pivot wear, needle unbalance
and other deficiencies of the moving coil meter can further degrade accuracy. On the other hand, the
accuracy of a dmm is specified as a
percentage of the reading plus 1 digit.
A reading of 1.000 volt would have a
possible error of (1.000 X .001) + 1

-an

FULL 3 -DIGIT LED DISPLAY is used on

the Ballantine 3/24 dmm. Two rotary
panel switches provide 25 operating
ranges including one for battery check.
A flashing left -hand digit and an indication of less than 200 indicate a reliable
reading between 1000 and 1200. Automatic polarity indication when measuring dc voltages and current. Ranges are:
1000 mV, 10, 100 and 1000 Vdc; 100 and
1000 A, 10, 100 and 1000 mA dc and
ac; 1000 mV, 10, 100 and 500 Vac; 100,
1000, 10,000, 100,000 ohms and 1 and
10 megohms.

.002 volt.
Auto -ranging is a feature of some
dmm's. The operator selects the desired function (volts, current, resistance, etc.) and connects the test leads
to the point or component being meaor

ANALOG OUTPUT AND DISPLAY are

features of the Simpson 360 that are
unique in dmm's in its class. The analog output terminals of the 360 provide
1 Vdc (open- circuit) corresponding to a
digital reading of 1000. This analog signal voltage can be used to drive a
graphic recorder.
The analog meter is a zero -center
instrument that is handy for peaking,
nulling and making other adjustments
on circuits evolving rapidly varying
signals.
The 360 is a 31/2 -digit instrument employing 7- segment LED display elements.
It can operate from 117 or 240 Vac, 50400 Hz lines. For complete isolation
from power lines or in cases where ac
power is not available, rechargeable
NiCad batteries provide up to five hours

CONDUCTANCE AND LEAKAGE current are two unique features of the

Tekelec 357 Multex dmm. Like the TA
355 and TA 356, the TA 357 has optional
transmissive or reflective liquid -crystal
readouts, ZERO control and Touch -nHold probe. There are six decade voltage ranges covering 0.1999 volt to 19.99
kV. Input impedance is 10 megohms on

the first three ranges and 1000 meg ohms on the 1.999- and 19.00 -kV ranges
with the 100:1 HV probe. An ON -OFF
switch displays the ac line voltage when
the ac -volts function is selected.
Current (ac and dc) is metered in
0.1999, 1.999, 19.99 and 199.9 mA
ranges. Conductance is mhos is measured in four ranges: 2 X 104, 2 X 10-',
20 X 10.6 and 200 X 10-6. Leakage current ranges are 10 pA, 100 pA and 1 nA.
Size 2% x 51/4 x 91/2 in. $179.
31/2 -DIGIT

DISPLAY makes the B

Precision model 282 the "Big
Brother" of the 281. It reads voltages in
four decade ranges from 1.000 to 1000
volts ac and dc. The 100% overrange
feature permits maximum readings of
1.999, 19.99, 199.9 and 1999 on all
ranges. On the 1 -, 10-, and 100 -Vdc
ranges accuracy is 0.5% of the reading 1 digit and 1.0% of the reading
1 digit on the 1 -kV range.
On ac volts (50 to 200 Hz), accuracy
is 1.0% of the reading 1 digit on the
three lowest readings and 1.5% of the
reading 1 digit on the 1 -kV range. Accuracy (50 to 1000 Hz) is 1% on the
1 -, 10- and 100 -V ranges and 1.5% on
ITS
&

Accuracy is 0.2% of reading +1

digit on 1000 mV dc, 0.5% of reading
+1 digit on 10, 100, 1000 Vdc and the
five current ranges; -1% of reading
+2 digits on acV; 1.5% of reading
+2 digits on ac current and 1% of
reading +1 digit on all resistance
ranges.
The optional 10850A peak detector
can be used to measure sinewaves to
beyond 500 MHz. Maximum input signal
is 30 Vac. The optional 10800 HV probe
measures dc up to 30 kV.
The 3/24 operates from any one of
four dc power sources: NEDA type 1603
dry cell battery, any external 6.2-10-

volt source delivering 50 mA, a voltagedropping network or the Ballantine 32401

dc adapter permitting operation from 9.8
to 34 volts dc at 10 to 100 mA, depending on the input voltage and setting of
the display brightness control. Ac operation is from the optional 32402A
plug- mounted supply requiring 100 to
135 Vac at 3 watts. The unit stores in
the dmm's battery compartment. A
32403A rechargeable NiCad battery supply powers the dmm for 16 hours and
incorporates a charger that restores full
charge in 16 hours. Fits in battery compartment and operates from 100 -125
and 200 -250 Vac, 48 -420 Hz.
The 3/24 is 5.5 x 2.4 x 7.1 in., and
weighs 2 lbs. with battery. $195.

of continuous operation. Recharging is

automatic when the line cord is plugged
in and the function selector is in the
BATT CHRG ONLY position. A LED on
the panel shows when the battery is being charged.
The function selector switch has four
positions: OFF disconnects all power
from the internal circuits; BATT CHRG
ONLY fully charges the battery in 16
hours; DC OHMS connects the appropriate input jacks for measuring dc current, voltage and resistance; depending
on the setting of the range selector. AC
connects the appropriate panel jacks to
the ac voltage or current metering circuits selected by the range switch.
Voltage ranges are from 200 mV to
1000 Vdc and 600 Vac. The 0 -200 and
0-2000-ohm resistance ranges are "low
power" with a maximum 150 mV open circuit. The other ranges are 20K, 200K,
2 megs and 20 megs full scale.
Input jacks -20 A, 200 AA, 2 A and
10 A -are used for current measurements with full scale values selected by
the range switch with accuracy 0.5%
of the reading +1 digit (except on 2 A
and 10 A ranges where accuracy is
1% of reading + 1 digit). Six ac
ranges cover from 200 A to 10 A. Accuracy 1.0% of the reading +1 digit
through 200 mA; 2.0% of reading +2
digits on 2- and 10 -amp ranges.
Size 7.2 X 5.4 X 3.75 in., 4.5 lbs.
$295.

48
www.americanradiohistory.com

the 1.5 -kV range. Response is 0.5 dB,

1000 to 10,000 Hz on the 1- and 10 -volt
ranges; 1 dB, 1000 -10,000 Hz on 100 V range and 1000 to 2000 Hz at 1 kV.

Resistance is measured in six decades

from 100 ohms to 10 megohms. Accuracy is 1% of reading 1 digit, 100
ohms to 1 megohm; 2% of reading
on 10 -meg range.
The test probe has a selectable 100K
resistor that is used in making measurements in high- impedance and high -frequency circuits. This resistor, in series
with the 10 -meg internal voltage divider
causes a -1% error in the reading. When
precision is needed, increase the meter
reading by 1 %.
Operates from 105 -125 Vac, 50 -60 Hz.
31/2 X 7 X 9 in., 3 lbs. $200.

BUILT IN A PROBE, the Hewlett- Packard

model 970A has automatic ranging, zero
and polarity indication.
The voltmeter ranges are 0.1, 1.0, 10,
100 and 1000 volts with 500 V dc and
ac maximum input. On dc the accuracy
is 0.7% of the reading +0.02% of the
range. On ac, accuracy (1 V to 1 kV) is
+2% of the reading +0.5% of the range
-from 45 Hz to 1 kHz. From 1 to 3.5

Dana Laboratories
2401 Campus Drive
Irvine, CA 92664

sured. The dnim automatically selects

the correct range and positions the
decimal point to give the most accurate reading.
Now that we've had a look at the
dmm. let's take a look at the pertinent
specifications of dmm's in the $300
and under range.

Data Precision Corp.

Audubon Rd.
Wakefield, MA 01880
Data Technology Corp.
2700 Fairview St.
Santa Ana, CA 92704

MANUFACTURERS

DigiTec (United Systerr E corp.)

918 Woodley Rd.
Dayton, OH 45403

Ballantine Laboratories
PO Box 97
Boonton, NJ 07005
B & K,

Div. of Dynascan Corp.

John Fluke Mfg. Co.

PO Box 7428
Seattle, WA 98113

1801 W. Belle Plaine Ave.

Chicago, IL 60613

kHz, accuracy is 3% of reading +0.5%

of range. Five ohmmeter ranges cover
from 1K to 10 megs with accuracy of
+_1.5% of reading +0.2% of range.
Accessories include 5 -range dc and
ac ammeter adapters measuring 100
to 1 A fullrange, an rf probe that
adds 100 kHz to 500 MHz to the ac

Heath Co.
Benton Harbor, MI 490

LIQUID- CRYSTAL DISPLAYS using field effect 7- segment devices are featured in
the Tekelec model TA 355, TA 356 and
TA 3E7 dmm's. The TA 355 bench model
and the TA 356 portable dmm have five
functions, 25 ranges with pushbutton
range and function selectors. Sensitivity
is 100 V on ac and dc voltage, 100 nA
ac and dc and 0.1 ohm.
The standard displays are transmissive types -black on a white back grourd. The optional reflective displays
are black on a grey -green background.
The ZERO control is a screwdriver adjustment on the 355 and a thumb -wheel
control on the 356. Range -to -range shift
is 1 digit, maximum. The reading rate
on the portable is fixed at 3 per second.

?2

Hewlett- Packard Co.

1501 Page Mill Rd.
Palo Alto, CA 94304
i
Keithley Instruments Cr:.
28775 Aurora Rd.
Cleveland, OH 44139

Non -Linear Systems

PO Box N
Del Mar, CA 92014

Schneider Electronics
11 Riverside St.
Medford, MA 02155
Simpson Electric Co.
853 Dundee Ave.
Elgin, IL 60120

measurement range of the 970A.

Size 61/2 x 13/4 X 11/4 in. 3 lbs. $275.

Tekelec, Inc.

FIVE MODELS in the Weston series

4400 of dmm's are within the $300 limit
set for this listing. They vary in accuracy, number of ranges, functions and
the type of operation. They are all 31h-

Weston Instruments
614 Frelinghuysen Ave.
Newark, NJ 07114

31829 W. La Tienda Dtiv,!

Westlake Village, CA 51::131

digit instruments. The 4440, 4442

(shown) and 4443 are self- contained
portables with rechargeable battery
packs that deliver up to twelve hours
of continuous power. The 4448 and 4449
are for use on 117 Vac, 60 -Hz only.
Models 4442 and 4449 have twenty
ranges covering from 20 mV to 1 kV ac
and dc, 200 ohms to 20 megs plus 199.9

A 3- position rocker switch on the 355

selects 3 readings /second, 1 reading/

second or "hold" the reading indefinitel}.

The TA 356 operates from internal rechargeable NiCad batteries with a life
of about 6 hours per charge with the
transmissive display and 8 -10 hours
with the reflective display. The separate
power supply /battery charger is standard for either 117 V, 60 Hz or 230 V,

A TEMPERATURE RANGE if 50 C to
+200 C is a unique fea`Lre of the
Digitest 610, a product t) Schneider
Electronics, Inc. It is a 41 digit instrument with four piano-type fi nrtion keys

-for

temperature, resistarcf

voltage

and current -along the righi e Ige of the

case and six range keys actes the bottom. It operates from bu It n NiCad
batteries and from 117 or 2;t0 V, 506- Hz. A BATTERY -TEST function is in-

cluded.

50 Hz.

A and

1.999 mA dc and ac current

ranges. The 4443 measures only dc
volts and current and resistance in the
same ranges as the other instruments
in the series.
All instruments in the 4400 Series are
2.25 X 5.45 X 7 in. and weigh less than
2.5 lbs. Prices range from $220 for the
model 4448 to $275 for the 4442.

The TA 355 can be specified to operate from either 117 Vac, 60 Hz or 230
Vac, 50 Hz. Interchangeable NiCad batteries and charger /ac supply are optional.
Dc and ac voltage ranges are 0.1999,
1.999, 19.99, 199.9 and 1000 volts. Current ranges are 0.1999, 1.999, 19.99,
199.9 and 1999 mA. Resistance ranges
are 0.1999, 1.999, 19.99, 199.9 ohms and
1.999 megohms.
Options are Touch -n -Hold probes and
BCD printer output (TA 355 only). The
TA 55 is 31/2 x 81/2 x 123/4 in.; the
TA 356 is 23/s x 51/4 x 91/4 in. $289 each.

www.americanradiohistory.com

Resistances from 0.1 ohn t:7 5 megs

are measured in five ranges. Ae and dc
currents from 100 nA to 1 riA are measured in one range; voltage f(pm 100 V
to 1 kV in four ranges.
4.73 X
The Digitest 610 is 3.35
9.06 in., 3.5 lbs. with batterie >. $295.

(Product Listing continues

)r7

page 81)

THINGS ARE GOING DIGITAL ALL OVER

they can be made with letters, etc.)

Each cathode is switched on to display
the digit.
The latest thing is a light- emitting
diode (LED) readout. These are mostly of the GaAs type, and emit red
light with only a very small amount of
voltage and current (other materials
are used to produce green or yellow
readouts). There are two major types;
the dot and the "seven- segment" type,
with seven bars. These are arranged ii
a pattern like Fig. 1. To make an "8 ",
all bars are activated. To make a "3 ",
bars A, F, G, E and D are energized,
and so on.
The LED dot displays work just like
the 7- segment bar type, but they use

er) are often combined in the same

IC. It decodes the BCD ( Binary -Coded- Decimal) signals from the Memory- Latch, and converts them into signals to actuate the display.
The Memory -Latch is fed by the
Decade Counters; we'll trace this out
in a moment. The main difference between Nixie and LED readouts is the
voltage. Nixies use about 100 volts,
LED's about 15 volts. So, LED's work
well with the low -voltage 'ITL IC's
used in the control circuitry. LED's,
however, do draw more current than
the Nixie type display and do not use
very much less power.
Now let's follow the control process through, from the counter inputs.

the place. Aside from the advantage of

getting a definite figure for a given
reading, the digital- readout instruments
have the advantage of high accuracy.
A lab instrument can be as accurate as
0.002 %, and field type instruments
are now in use at 0.2% and even better.
There are places where the old -fashioned D'Arsonval meter still has a
slight advantage. It is easier to see a
peak in a reading with a meter -needle,
or sudden current -surges, etc. However, for use in labs, R &D, and service
work, the precise figures displayed by
the digital readouts is definitely better. In many modern circuits we must

Digital Instruments
For Electronics

by JACK DARR
SERVICE EDITOR

REF

REF

REFERENCE

ENABLE

INTEGRATING
RANGE
RESISTOR

<

0
0
0
0

A
F

O O O O O
A

I-

CAPACITOR

CONTROL
LOGIC

EINO

0
0
0
0

INTEGRATOR
AMPLIFIER

ZERO
CROSSING
DETECTOR

COUNTERS

STORAGE

MOS

O O O O O
O

DIGIT

1111111

DRIVE
TRANSISTORS

DRIVE TRANSISTORS

STROBE

o
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o

O(--"Tho
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CLOCK

MULTIPLEXER

INTERNAL

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0 00 00

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1-

FIG.
SEVEN -SEGMENT DISPLAYS using LED's.
type, and b -The dot type. Five dots equal one bar.

be pretty accurate; transistor voltages,

etc. The digital readout gives us our
measurement as "10.75 volts" or whatever is called for. (It is slightly disconcerting to some old goats to see such
a reading displayed as "10.7543 volts "!
It takes a little practice to learn to ignore the "LSD" which is not a chemical but "Least Significant Digit"!)

How they work

Digital readouts are made with several different types of display units.
The original was the Nixie tube made
by the Burroughs Co. It is a cold -cathode tube like a neon lamp. It has a
common anode, and ten cathodes
through 9 (in the most common type;

-0

-Shows

the bar

2-

FIG.
DIGITAL METER CIRCUITRY using MOS IC's and LED display. Display units light in sequence, but so fast that there's no flicker.

sets of four or five individual LED's

to make the equivalent of the bar.
Liquid -crystal displays have been used
in some instruments, but there are still
some drawbacks-visibility to name
just one. As a result, they're not quite
as common as the others.
The control circuitry
All of these readouts use a control
system which is basically similar. Starting at the display unit and working
back toward the input, we go through
a Display Driver. This is a set of solid state switches which controls the illumination of the desired segments of the
display. It is fed by a Decoder. These
two circuits (decoder and display driv-

50
www.americanradiohistory.com

The decade counters do just that;

count to ten. Their input will be a
series of digital pulses, usually BCD,
from the input of the instrument. Each
of these counts up to 9 pulses, then
transfers the tenth pulse to the following decade counter and starts over.
The counters are connected in series;
each one controls one of the digital
readouts. The first operates the "units"
readout, the next the "tens ", next the
hundreds, and so on and on.
Their input signal is controlled by
a "clock oscillator"; its high frequency
has been divided down to get a longer
sampling period. A sampling circuit
controls the gating of the input signal
into "slices" of a given time -duration,

say 1.0 ms. If we're counting a frequency, these circuits will slice off a
1.0 ms sample, square it into square
waves, and feed it to the decade counters.
The counters receive the input for
the period of time selected by the instrument controls. While doing this, the
first decade counter counts up to 9,
then passes the next pulse along to the
tens counter. This one takes the first 9
counts, and then passes along a "100"
count to the following counter. This
can go on as long as necessary, depending on the number of units (digits) in the display, and the signal being counted.
At the end of the counting or sam-

commands them to deliver one output

(that is, the output signal which will
light only one digit of the display) for
giver combinations of high and low
on the inputs. A Nixie driver will have
the four logic inputs, and ten individual outputs, one for each digit. The
one corresponding to the desired digit
will go low (grounding the proper
cathode in the tube) and all others
will remain high. In a Nixie display,
all of the tubes light at the same time.
For LED displays, the same basic
circuitry is used. But there can be
some differences in the actual operation. For example, the Weston panel meter unit, Model 1221, in Fig. 2, has
a four -digit LED display. This one

obtained with low- voltzge TTL

logic units, since it takes only a few
volts to bring an LED to full brilliance.
Needless to say, this kirld of work
can only be done by liber use of
integrated circuit technology. In many
of the new instruments, even these are
being supplanted by large sale integrated MOS IC's (LSI -MOS). Fig. 3
shows the "works" of a Weston Model
1230 bipolar panel- meter. Fig. 4 shows
220 and
a front view of the Mode
1221, which does the same toting with
only a single LSI chip! You :an do it
with discrete transistors but you'll need
a U -Haul truck to carry it around!
ily

3-

FIG.
INSIDE A DIGITAL PANEL METER.
This unit is a Weston Model 1230.
6 -THIS FREQUENCY COUNTER has
eight digits in its readout and goes out to

FIG.

120 MHz.

FIG.

8- HIGH -FREQUENCY

MENTS can be made with inst

H -P 5354A. It goes to 4 GHz.

EASUREvents like

-A

SINGLE IC does all the work in

this digital panel meter.
FIG. 4

NEI

5-

HEATHKIT MODEL IB -1100 frequency counter uses Nixie type readout.

FIG.

the total number of

counts is present on the string of
counters, as logic highs or lows at
their terminals. Next, a "transfer pulse"
commands the counters to send the
stored numbers along to the Memory
Latch, and reset themselves to zero.
These memory latches transfer the
stored signals to their outputs when
the transfer line goes to a logic low,
they "remember" the figure, and hold
it. This is then transferred to the decoder- drivers.
These decode the BCD signal, which
is on four lines (called A, B, C and D
to avoid confusion with figures (and
we'll have enough confusion as it is).
The "truth- table" for the decoders
piing period,

-A

FIG. 7
FREQUENCY COUNTER CAN be
usec to check the frequency of an amateur

radio rig.

uses a seven- segment display.

A mildly unusual method of lighting the LED's is used. The count

comes through the logic, the multiplexer unit, and goes to seven lines
leading to the display. All lines are
connected to each LED unit, in parallel. To display different figures, the
enti-e display is "strobed" by the second set of drive transistors; in other
works, each unit is flashed in sequence,
by :he strobe signal from the multiplexer. So it displays only the digit
which its logic signals tell it to.
The scanning is so fast that the display seems to be continuously lit; in
this instrument, at a 100 -Hz rate. This
kind of switching and scanning is eas-

9- COMBINATION

INSTftIJ ,1ENT is a
analyzer and a selective voltmeter.
Interesting combination of digit.] meter and
analog meter.
FIG.
wave

Typical instruments
Now let's look at a few o the ways
n be used
in which a digital readout
to improve the usefulness of an instrument. We have always had instruments which were potentially very accurate; now we have a readout that
can match this. For the .irst, look
again at the Weston Dig tal Panel
Meter in Figs. 3 and 4. This; is a simple (On the outside, anyhow!) black
box.
It is basically a voltmeter. By selecting values for built -in rargc resistors,
it can be anything from a I) Io 100 -mV
voltmeter to a 1000 -volt meter. Dc
current from 10 mA ( fu -scale to
100 mA can also he read. A c voltages
1

51

www.americanradiohistory.com

and currents can be read with an ac

adapter, Model 9744.
Data can be provided to make the
model 1220 or 1221 read engineering
units-feet, pounds, rpm, pressure,
and so on. The only difference between the two models is the power
supply; the 1220 uses 5.5 volts dc,
and the 1221 is 117 -volt ac powered.
Frequency -countnig is one of the
tricks that digital readouts do well.
The Heath Co. has four models, the
IB -1100 (5 digits, to 30 MHz), the
IB -1101 (5 digits, to 100 MHz +),
the IB -1102, (8 digits, to 120 MHz)
and the IB -1103 (81/2 digits, to 180
MHz). These are shown in Figures
5 and 6.

FIG. 10 -VHF SIGNAL GENERATOR (450

kHz to 550 MHz) has digital readout to show
what frequency signal it is producing.

Figure 10 shows the H -P 8640B vhf

signal generator, with a digital readout that can be used to show the output frequency, or to read the frequency of an external signal. It will go
from 450 kHz to 550 MHz, on AM or
FM. The D'Arsonval meter on the panel will also do tricks! It read AM modulation percentage, FM peak deviation
or output level in dBm or volts, and it
is an autoranger. No switching is needed; it adjusts itself.
Figure 12 shows an H -P Model
5270A Automatic Capacitance Bridge.
It has a dual digital readout; one reads
the capacitance, and the other the dissipation factor or conductance, whichever is desired, simultaneously.

to a signal that is drifting or changing

in frequency. Indicator lights on the
panel tell whether the circuit is locked
or unlocked to the signal.
Figure I1 is the front panel of an

oscilloscope. Innocent-looking enough,

isn't it? It isn't. This is a digital oscilloscope, the Nicolet Instrument Corp.
Model 1090. The difference lies in the
way the signal can be displayed. A
standard analog scope displays the instantaneous waveform. Storage scopes
can hold it, on the special screen of
the crt. In the Model 1090, the signal
is not fed to the crt. It goes, instead,
to a memory bank with a capability of
storing 4096 words of 12 bits each.
To display the recorded waveform

FIG. 12- AUTOMATIC CAPACITANCE

BRIDGE has a dual digital readout.

FIG. 14- AUTORANGING FREQUENCY

counter by John Fluke Company uses LSI
MOS IC's.

11- DIGITAL SCOPE made by Nicolet

Instrument converts visual signals into digital
FIG.

code and then remembers the code so it

can display the remembered waveform on
demand.

FIG. 13- ELECTRONIC STOP WATCH by

TAFCO is a different kind of digital instrument.

Hewlett- Packard makes a Model

5307A counter. It is basically a frequency counter, but with the proper
transducers can be used for many
measurements; vibration, shock, transients, and so on. The Model 5307A is
a high -resolution type.
Figure 7 shows another use for a
frequency counter. Here, the HewlettPackard Model 5382 is being used to
check frequency on an amateur rig.
This would be the height of something
or other to me! Carrier frequency can
be accurately read to within 10 Hz!
Figure 8 shows an H -P Model
5354A counter. It will go to 4 GHz,
and lock automatically on pulse- trains,
as well as CW.

Figure 16 is another capacitance

meter. This one is the H -P Model
4282A High Capacitance Meter. The
unusual thing about it is its top range;
it will go to

ONE FARAD. (When

first went into this business, one Farad

was literally an inconceivable quan-

tity.) The 4282A will make other

handy measurements too: the internal
capacitance of a battery; capacitance
of a transistor, and so on.
Figure 9 shows an interesting combination instrument; the H -P 3681A
Wave Analyzer and Selective Voltmeter.
Tuned to a known frequency component of a signal, this instrument will
read it to five -digit accuracy, or 1.0
Hz. It has afc which allows locking it

52
www.americanradiohistory.com

FIG. 15- UNIVERSAL COUNTER -TIMER

from Tektronix.

the controls are adjusted, and the waveform is repeated indefinitely. Cross hair vertical and horizontal lines on
the display can be adjusted to intersect any part of the waveform. When
this is done, by pressing the COORDINATES button under Numerics, the
time since the trigger is shown on the
bottom of the crt screen in figures, at
the left side. On the right side is displayed the voltage of the waveform at
that point, also in figures. By adjusting the controls, any point along the
whole length of the 4096 -word recorded waveform may be frozen and studied. One engineer told me that this
was equivalent to a scope with a trace
twenty -two feet long.

Nicolet Instruments also offers their

Model 93 plug -in for their scope. This
has a dual channel input. Either input
may be recorded in the memory bank,
at will. Note the STORAGE CONTROL
pushbuttons in the center. By pushing
HOLD NEXT the memory records the
waveform that comes along after the
next trigger signal. HOLD LAST records
what followed the last trigger. LIVE
shows that waveform as it is actually
taking place, in real time. The Model
93 plug -in will even display the stored
information while watching live signals, at the same time.
Figure 13 shows still another use.
This is an electronic stop- watch, with
a digital readout. Using a crystal -con-

the same well known company, another unit in the same series, with a
slightly different form of digital readout, is a dc power supply. It is very
tightly regulated, and the exact voltage
output is shown on the three- thumba special kind of
wheel control
"digital readout ".
Tektronix also make a 550 -MHz
Frequency Counter, with digital
readout, plus indicator lamps to make
sure you know where you are in the
band. Fig. 15 shows a Model DC -505
"Universal Counter -Timer", which will
do so many things that I'm not even
going to try. Check that panel.
A novel approach to the use of a
scope as well as a digital meter can be

events- counting, etc.) you set the figures on the thumbwheel dial ,. When
the number of events reaches the preset count, the DD -501 puts out a trigger pulse, for an oscilloscope or any
other type of triggered instrument.
A well -known name in Iht service
instrument field, the Simpson Electric
Co., makers of the famous old 260
vom, also shows up in the digital field.
Figure 19 shows an instrument that
might be called "Son Of 26(0" It's the
digital vom, Model 360. Tl re is also
a "lay -down case" type, the +fDdel 460
in the same line. The samt company
also makes a digital panel- rie:er (Fig.
20). This basic instrumeit can be
made to read almost any quantity de-

16- HIGH -CAPACITANCE METER accurately reads capacitor values as large as

FIG.

one Farad.

module with
digital display is part of new Tektronix instrument system.
FIG.

FIG.

17- DIGITAL

DELAY MODULE by Tek-

18-COUNTER/TIMER

tronix. Thumbwheel switch for getting count

is also digital readout.

FIG. 19-SON OF 260 is the Simpson model

360 digital vom.

trolled clock, it can be used in two

ways; for timing the overall time of
an event, and also for checking lap
times, etc. without losing the overall
count.
Figure 14 is an autoranging counter
from the John Fluke Co. It will go up
to 80MHz, and count as low as 5 Hz.
This versatile instrument is also made
possible by LSI chips.
Figure 18 shows one of the numerous combinations of instruments possible in Tektronix's new TM -500 series.
It shows an SG -503 oscillator, a DC
504 Counter -Time and a DM -502 Digital Multimeter, in a 3 -unit Mainframe. The power supply for all three
is provided by the mainframe. From

yours mounting a DM -40 DMM on

top of a 465 portable Oscilloscope.
Now, many things can be done. For
only one, you can read the time interval 'et wee n any two points on the
waveform; this is shown on the digital
readout in whatever units are needed.
Accuracy of this is within 0.1%.
A typical use of the plug -in concept
of tee TM -500 Series is in a Medical
Instrument Calibration System; it can
he used for calibrating EKG, ECG,
Crash-carts, and many other types of
medical electronic instrumentation.
Figure 17 shows an unusual digital
readout application. It is a Tektronix
DD -501 Digital Delay. To read any
desired count (for applications such as

FIG. 20- DIGITAL PANEL ME.-ER can be

used to read almost any quantty

FIG. 21 -MOST UNUSUAL DI(;

ment we found is this Green B:
Sobriety Tester.

instruScientific

4L
i

sired, with a few simple char ges. This

is the Model 2830.
Last but not least, we see to instrument that could conceivat ly cause
some arguments. It is made py Green
Bank Scientific Co., Box 1CO3 Green
Bank, W. Va., along with sev eral other
similar instruments. It's a diE ital -readout Sobriety Tester. You gut a definite
PASS or FAIL readout. Figure 21 shows
the instrument.
There are probably man- other uses
for these versatile and higl l ) accurate
instruments, but this is a re ,r :sentative
sampling of what is being Je le in the
R -E
field at the moment.

53
www.americanradiohistory.com

40

010300
Using COSMOS
Digital IC's
This is part Ill in

series of articles describing COSMOS IC's,

the latest in solid -state technology.
Monostable and astable multivibrator circuits are described
here, along with simple circuits you can build.
a

by R. M. MARSTON

IN PART II OF THIS SERIES WE LOOKED AT

the operating principles of COS /MOS

digital IC's, and explored a number of
practical ways of using the CD4001 IC in
inverter, gate, and logic applications. We
went on to discuss bistable multivibrator
applications.
In this third part of the series, we go
on to look at monostable and astable
multivibrator applications.

Monostable multivibrator projects

A basic monostable or one -shot multivibrator can be made from two NOT or
NOR logic gates by direct -coupling the
output of one gate to the input of the
other, and by coupling the output of the
second gate to the input of the first via a
simple R -C time constant network. Figure 21 shows a practical way of making
a basic monostable multivibrator, or pulse
stretcher, from one half of a CD4001
cos /mos IC. You can also use the
KD4001.
Here, gate A is used as a NOR logic
element, and gate B is used as an inverter
or NOT gate. The circuit action follows:
Normally, when the circuit is in its
quiescent state, the input to gate B is held
high via Rl, so the output at gate B is
low: Both input terminals of gate A are
thus low, so the output of gate A is high.
Consequently, since both ends of CI are
high, Cl is fully discharged.
Suppose now that a brief positive trigger pulse is applied to the input of gate
A. As soon as this pulse is applied, it
drives the output of gate A to ground
and drags the input of gate B with it via
discharged capacitor Cl: Consequently,
the output of gate B immediately goes
high, and thus holds the output of gate A
in the low state even when the input trigger pulse is subsequently removed.
As soon as the output of gate A goes
low as the result of the applied trigger

pulse, CI starts to charge via RI, and

an exponential rising voltage is applied to
the input of gate B via the R1 -C1 junction. Eventually, after a delay determined
by the R1 and Cl values, this exponential
voltage rises to the transfer voltage of
gate B, and at this point, the output of
gate B switches sharply back into the low
state. As the output of gate B goes low it
(SEE

TEXTI

o-

1.5 MEG

C1
14

TRIGGER

IPUT

L.../
1/4

CD4001
GATE A
GATE

1/4

R2
MEG

+5 TO 15V

RI

4- D1

,
1

SEC /vF

CD400I

L4
6

-1.

OUTPUT

voltage of the individual CD4001 IC

that is used.
Three points should be noted about
this particular circuit. The first point is
that, since the period of the circuit is
dependent on the transfer voltage of the
particular CD4001 that is used, the
period that is obtained using a particular
set of R -C values can vary considerably
between one CD4001 and another. The
CD4001 in fact has a production transfer voltage spread of 30% to 70% of the
supply voltage.
In practice, the transfer voltage of any
particular CD4001 is almost constant
over a wide range of temperature and
supply voltages, so the Fig. 21 circuit has
excellent stability, but must have its time
constant values individually adjusted to
give a particular timing period. The Fig.
21 circuit in fact gives a period of
roughly 1 second per AF of Cl value
when R1 has a value of 1.5 megohms.

TO PINS
8, 9, 12

AND 13

1.5 MEG

(START)

FIG. 21 -BASIC MONOSTABLE

VIBRATOR or pulse stretcher.

+5 TO 15V

R1

S1

MULTI -

14

Cl

causes the output of gate A to go high:

Cl then discharges rapidly via the output
of gate A and input protection diode D1
(see Fig. 7 -b, September 1974 issue) of
gate B, and the operating sequence is
then complete.
Thus, the output of the Fig. 21 circuit
is normally low, but goes high as soon
as a brief positive trigger pulse is applied
to the input: The output then remains
high for a certain period, and then
switches abruptly back to the low state
again: The precise period of the output
pulse is determined by the R -C time constant, and by the value of the transfer

54
www.americanradiohistory.com

1/4

CD4001

-i

GATE A
GATE
1/4
5

SEC /uFI-

CD400I

.--

L
OUTPUT

R2

100K

TO PINS
8, 9, 12

AND 13

22- "NOISELESS" PUSH BUTTON or

manually- triggered monostable.
FIG.

+5 TO-15V

D1

31

L TEXT)

R1

(START)

(SEE

MEG

14
1

R4
1K

Cl

1/4 CD400I
GATE A
GATE
1/4

R3

1K

CD400I
OU/ PUT

R2

R5
1K

0-41.

MEG

"D2

D2'

TO PINS

8,9,12 AND

R1=R2
13

Cl

C2

LOW- LEAKAGE GENERAL -PURPOSE SILICON DIOCE

FIG. 23 -BASIC COMPENSATED monostable multivibrator.

+5 TD 15V
R1
1

MEG

14

D1"

_fl
Cl

1/4

CD400I

OJ

1/4

CD400I

01

INPUT

OUTPUT

R4

100K

R2
MEG

R3
1K
C2

F
I
I

SEC/F

TO PINS

R1 = R2

8, 9, 12 ANC 13

Cl

C2

LOW- LEAKAGE GENERAL -PURPOSE SILICON DIODE

"D1

FIG.

24- IMPROVED COMPENSATED

monostable multivibrator.

Cl can have any value between a few

pF and hundreds of F: The value of R1
can range from a few thousand ohms to
thousands of megohms, if required.
The second point to note about the
circuit is that its input must always be
tied to ground in the absence of the positive trigger pulse: This requirement can
be met by applying the input from a
permanently connected dc source, or by
strapping the input terminal to ground
via a 1- megohm resistor, as shown dotted
by R2 in the diagram.
The final point to note is that, since an
exponential voltage is applied to the input of one of the gates during the operating cycle, the gate is driven into its
linear region during each operating cycle.
A measurable current thus flows in the
circuit during the operating period. All
cos /Mos monostable and astable multi vibrator circuits in fact pass a measurable
current when they are in their functional
modes.
Figure 22 shows how the circuit in
Fig. 21 can be used as a `noiseless' pushbutton or manually- triggered monostable
by simply using the push- button to apply
the positive trigger pulse to the circuit.
It has already been pointed out that
a snag with the basic monostable circuit
of Fig. 21 is that its period depends on
the transfer voltage of the individual
CD4001, and is not dictated solely by

the R and C values. Figure 23 shows the

basic circuit of a compensated monostable multivibrator that does not suffer
from this snag. The diagram also shows
the basic waveforms of the circuit. Note
that the circuit uses two sets of R -C
time -constant components. Circuit operation is as follows:
When the circuit is in its quiescent
state the S1 side of Cl is grounded via
R3, but the R1 side is held positive: Cl
is thus fully charged under this condition,
and the input of gate A is high. The output of gate A is thus low, so C2 is fully

discharged at this time, and the output of

gate B is high.
Suppose now that START button SI is
briefly closed and then released. As SI
is closed, the SI end of Cl is connected
to the positive supply line, and CI discharges rapidly via R4 and D1 (which is
one of the input protection diodes built
into the CD4001) This action has no
effect on the circuit. When S1 is released,
however, CI is fully discharged, so as
soon as Si is released, Cl starts to recha-ge via R1, R3, and R4, thus pulling
the input of gate A low and making the
output of gate A go high: As the output
of gate A goes high, it charges C2 rapidly
via D2, and thus causes the output at
gate B to go low.
As soon as SI is released, Cl starts to
charge up, and a rising exponential volt:

age is applied to the input of (-ate A.

After a time determined by the 21 and
Cl values, this voltage RISES to the
transfer voltage of gate A, and at this
point the output of gate A switches
sharply into the low state anc removes
the charging voltage from C2 is D2 becomes reverse biased. C2 then ;tarts to
discharge via R2, and after a taw. determined by the R2 and C2 values, the C2
voltage FALLS to the transfer voltage of
gate B, and at this point the output of
gate B switches sharply into t ie high
state. The operating sequence _af the circuit is then complete. Note that R4 and
R5 are used purely as safety tesistors,
and prevent heavy capacitor discharge
currents from flowing into the IC gates if
power is removed from the circ uit during the operating sequence.
Now, this particular circui uses two
identical R -C time constant networks,
and its final output period is equal to the
sum of the two individual time constants.
The important point to note, ho Never, is
that one of these time constants causes a
circuit action when its exporten_ial voltage RISES to the transfer voltage of gate
A, and the other causes a circuit action
when its voltage FALLS to rte transfer
voltage of gate B. ConsequenC -y. if both
gates have identical transfer vel ages, the
transfer voltage values effectively cancel
out, and have no effect on the actual
period of the circuit.

For example, if both gates h -ve transfer voltages of 30 %, Cl will have to

charge to 30% of the suppl3 '. oltage to
cause gate A to change state. and C2
will discharge by 70% of the supply voltage to cause gate B to change tate, thus
giving a total voltage change Pf 100 %.
If, on the other hand, both gates have
transfer voltages of 40 %, Cl a ill charge
to 40% and C2 will discharge by 60%
during the operating sequence. again giving a total voltage swing of 1)0%. The
total period of the circuit is :hus independent of the transfer volt.ree value of
the IC, providing that both (rates have
identical transfer voltage value;.
Now, although transfer vo:t age values
can vary over wide limits bet.veen individual cos /Mos IC's, the individual transfer voltage values of a set of gates within
a single CD4001 are alwty. virtually
identical, since the gates are all formed
on the same semiconductor chip at the
same time. Consequently, the total timing
period of the Fig. 23 circuit is dictated
purely by the values of RI I and R2C2, and is independent of vi nations in
the parameters of individe..1 CD4001
IC's.
The Fig. 23 circuit is sh skn as being
manually triggered. The c rc_tit can be
modified for electronic triggering by
simply eliminating 51 and a plying the
positive trigger pulse across R3. In either
case, a practical disadvantage of the circuit in Fig. 23 is that the actual monostable action is initiated b.. the end,
rather than the start, of the 1put trigger
pulse. This snag can be oN ercome by
modifying the circuit as shovwty in Fig. 24.
This circuit gives an output that is
normally high (positive), bct which goes
low (to zero volts) for a p-eset period
when a trigger pulse is apllied. If re-

55
www.americanradiohistory.com

IF

YOU ARE READY FOR SERIOUS CAREER

Learn College -Level

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www.americanradiohistory.com

)uncil

quired, the polarity of the output signal

can be reversed, so that it is normally
low but goes high for the duration of the
output pulse, by simply wiring an inverter into the output of the circuit in
Fig. 24, as shown in the positive- output
compensated monostable circuit of Fig.

+5 TO 15V
R1
1

14

MEG

INPUT

D1'

25.

1/4

CD400I

1;4

CD400I

C1

3
i

OUTPUT

--I
I

Astable multivibrator circuits

The most widely used type of multi vibrator circuit is the astable, or square wave generator. Figure 26 shows how
one half of a CD4001 cos /mos IC can
be used to make a basic 1 -kHz astable
multivibrator. Note that both gates of the
circuit are connected as simple inverters,
and that the circuit uses only a single set
of R -C time constant components. The
action of the circuit is as follows:
Suppose initially that a stage has been
reached in the circuit operation where the
output of gate B has just switched into
the high state and the output of gate A
has just switched into the low state, and
that Cl is fully discharged at this moment.
Since Cl is discharged at this time,
the input of gate A is effectively shorted
to the output of gate B, and is high. As
soon as the above stage of operation is
obtained, Cl starts to charge up via R1
and the low (effectively grounded) output of gate A (which is derived from
the R1 -C1 junction) starts to decay exponentially towards zero.
Eventually, after a delay determined
by R1 and CI, the input voltage of gate
A falls to the transfer voltage point of
gate A and at this instant, the output of
gate A switches into the high state and
drives the output of gate B into the low
state: As the output of gate B switches to
the low state, it forces the positive end
of Cl downwards, and thus forces the
gate A input end of Cl to attempt to
swing negative with respect to the zero
volts line: As the input of gate A goes
negative to the zero volts line, input protection diode D3 (see Fig. 7 -b, September
1974 issue) conducts and removes the
charge from Cl.
Thus, at the end of this switching
cycle, Cl is again fully discharged, the
output of gate B and the input of gate
A are low, and the output of gate A and
the input of gate B are high.
As soon as this new stage of the operation is obtained, Cl starts to recharge in
in the reverse direction via R1 and the
low (grounded) output of gate B, and
the voltage at the input of gate A (which
is derived from the R1 -C1 junction)
starts to rise exponentially towards the
positive voltage. Eventually, after another delay determined by R1 and Cl,
the input voltage of gate A rises to the
transfer voltage of the gate and at this
instant, the output of gate A switches
into the low state and drives the output
of gate B into the high state.
At this moment, Cl discharges rapidly
via input protection diode Dl of gate A
as the R1 -C1 junction end of the capacitor attempts to go positive relative to
the positive supply line, and the operating sequence is then complete. The
switching sequence then repeats ad infinitum, and a series of approximately

INPUT

R24
.1

SEC /F

TO PINS

MEG

~1.12 AND

13

R1=R2
`D1

Cl

LOW- LEAKAGE GENERAL PURPOSE SILICON DIODE

25- POSITIVE- OUTPUT compensated

monostable multivibrator.
FIG.

HIGH (OFF)
LOW (ON)

GATE INPUT

+5 TO 15V

= C2

+5 TO 15V

f-ON-I
+

14

OFF
2

OUTPUT A
R1

1/4

680K

OUTPUT A

CD4001

1/4

GATE A

1/4

--ON

1/4

CD4001
OUTPUT

-KHZ

-I
o

OUTPUT

6
B

TO PINS

26 -BASIC

CD400I

8,9,12 AND

Cl
001

680K

FIG.

CD4001

R1

Cl
001

GATE

R2
100K

TO PINS
8, 9, 12 AND 13

13

ASTABLE

multi-

vibrator or square -wave generator.

FIG.

28 -GATED

-KHZ

ASTABLE

multi-

vibrator.
+5 TO 15V

+5TO15V

GATE
1/4

CD400I
4

OUTPUT

TO PINS

TO PINS

8, 9, 12 AND 13

8,9,12AND13

FIG. 27- VARIABLE FREQUENCY (600 Hz6 kHz) astable multivibrator.

FIG.

square waves are generated at the two

outputs of the circuit: Outputs A and B
are 180 out of phase.
An outstanding feature of the basic
astable multivibrator circuit of Fig. 26
is that it uses only two time constant
components (R1 and C1), and the values
of both of these components can be
varied over wide ranges to give required
operating frequencies. The value of R1
can be varied from a few thousand ohms
to thousands of megohms, and Cl (which
must be a non -polarized capacitor) can
be varied from a few pF to several F.
The operating frequency is inversely proportional to the R1 and Cl values, and
can be varied from less than one cycle
per hour to several MHz.
The operating frequency of this circuit
can be made variable, if required, by

wiring a variable resistor in series with

limiting resistor R1, as shown in the
circuit of Fig. 27. With the component
values shown, this circuit covers the approximate frequency range 600 Hz to 6
kHz.
If required, the basic astable multi vibrator of Fig. 26 can be gated on or
off via an external pulse signal by connecting gate A as a NOR gate and applying the gating signal to one of the NOR
gate inputs, as shown in Fig. 28. The
multivibrator is cut off when the gate
input signal is high, and is operative
when the gate input signal is low.
The basic astable multivibrator of Fig.
26 acts as a simple and very useful circuit, but suffers from several disadvantages. The first of these is that, since the
(continued on page 88)

60
www.americanradiohistory.com

29- COMPENSATED

-KHZ

astable

multivibrator.

new FTC ratings

for audio amplifier power
are they any good?
There are some potential loopholes in the
newly imposed FTC rules. Here's a look at how they
work and where the problems may lie
by LEN FELDMAN
CONTRIBUTING HI -FI EDITOR

BY THE

TIME YOU READ THIS, MANY

manufacturers of home entertainment

audio products will be busily printing
new advertising literature, specification sheets and even the outside of
packing cartons. No, the industry has
not suddenly redesigned its entire prod-

uct line -the amplifiers haven't

changed that much. But they are
changing the statements regarding
their power output capability to bring
them into line with a new trade regulation promulgated on May 3, 1974
by the Federal Trade Commission.
The new rule becomes effective November 4, 1974 and the FTC will
consider violations after that date to
be "an unfair method of competition
and an unfair or deceptive act or
practice within the meaning of Section
5 (a) (1) of the Federal Trade Commission Act 15 U.S.C. S 45 (a) (1)
to violate any applicable provision of
this rule."
Reasons for the FTC action
Over the past few years, some segments of the audio industry have been
engaged in a quasi-technical semantic
race to devise power output statements
for audio amplifiers which would yield
higher and higher numbers of "watts
of output" for their products. About
the only thing these assorted specifications had in common was their use of
the word "watts" as a measure of
power. But what "kind" of watts were
used? There were "continuous watts"
-the amount of power that an amplifier would deliver on a continuous
basis into a fixed, resistive load.

This measurement, the most conservative of all, became known as rms

power, a term which in itself is semantically meaningless. The letters rms
stand for "root- mean -square." Many
ac voltmeters are calibrated to read
0.707 of peak sinusoidal ac voltage
applied to their terminals. In the case
of a sine wave, power developed across
a load is defined by the Formula
(Erne) -/R = P, where Em., is the
root -mean -square voltage, R is the resistive component of the load impedance across which the output voltage
is applied and P is the resulting power
in watts. Power itself cannot be termed
rms because musical waveforms are
seldom, if ever sinusoidal and as an
amplifier is driven into clipping or
overload, even a pure sinusoidal waveform changes shape so that voltmeter
readings no longer correspond to 0.707
of peak voltage values. Nevertheless,
the term "rms power" persists and for
our purposes can be considered identical to "continuous power"-the more
appropriate term.
Another term "music power" ( also
known as "dynamic power, IHF Dynamic Power or IHF Music Power")
has been used to describe amplifier
power output at somewhat higher
numerical values of wattage. The numbers are based upon the fact that for
short periods of time, most amplifiers
can deliver somewhat more power than
they can on a continuous basis. Since
musical waveforms contain relatively
short bursts of higher energy, many
experts felt that "music power" represented a more meaningful way to

describe an amplifier's power output

capability.

Unfortunately, "music power"

quickly became corrupted anc gave
way to such meaningless terns as
'peak power," "peak music p ower,"
instantaneous peak power (D'F ) and
even "instantaneous peak music power." Each of these successive manipulations of terms gave rise to higher
and higher wattage figures. It was not
uncommon to find products rated at
100 watts "IPP" which act'. uallyy produced 5 watts or less of "cont nuous
power." Small wonder that th FTC
stepped in and tried to bring some
order into these chaotic audio specs.
A summary of the FTC rule

To begin with, the new FTC regulation requires that all audio products
that deliver more than a 2 -wait output
must specify, in boldest advertising
type, the following with regt -d to
power output:
1.

"The minimum sine -wave <:ontinuous average power output, in

watts, per channel
a. for each load impedance for
which the equipment was designed
b. measured with all channels
driven

manufacturers rated power

band or power frequency response, in Hertz (Hz) for each of
the rated power outputs requ red
to be disclosed per item (1) and

2. The

manufacturer's rated
centage of maximum to ca

3. The

3ergar-

61

monic distortion at any power

level from 250 mW to the rated
power output for each rated power output and its corresponding
rated power band or frequency
response.

BOTH CHANNELS DRIVEN

RATED THD = 0.5%
130
120
110
100

of
the above, the following might constitute a proper power output disclosure:
"Brand "X" amplifier has a rated
power output of 50 watts per channel, all channels driven, into an impedance of 8 ohms, at any frequency from 20 Hz to 20 kHz, with
harmonic distortion not exceeding
0.5 %." Similar statements would
also have to be made with appropriate numbers substituted for 4

AMPLIFIER

p =
cc

5..?..

IT

70

60
50
40
30

"A"

AMPLIFIER "B"

20

111111

100

500

1K

5K 10K 20K

FREQUENCY (Hz)

FIG.

500

11111

5K 10K 20K

1K

power bandwidth.

Q 20

x310

1111111

100

2-

BOTH AMPLS
CARRY FTC
POWER RATING
OF 50W /CH

90

w 80

1111111

FIG.
"LOWER POWERED" AMPLIFIER A
can actually produce more power at frequencies in shaded areas because of its better

DRIVEN
THD = 0.5%

10

FREQUENCY (Hz)

Remaining ambiguities
To paraphrase astronaut Armstrong,
the new FTC rule represents "one
giant step" for the audio industry
but the typical hi-fi component purchaser can still be subjected to ambiguities and confusion even if the
new rules are strictly followed and
enforced. Consider, first, the two
power output curves of Fig. 1. Both
amplifiers "A" and "B" could he described exactly as in the example
LOADS

AMPLIFIER "A"
"75 WATTS /CH"

20

ohm and 16 -ohm loads, if the amplifier were designed to operate

into these additional load impedances.

BOTH CHANNELS

AMPLIFIER "B" "100 WATTS /CH"

90
80
70
60
50
40
30
20

A "Legal" power statement

Based upon our interpretation

8 -OHM

LOADS

8 -OHM

-POWER VERSUS FREQUENCY of

two amplifiers at 0.5% THD rating.

above. Each can produce 50 watts at

0.5% THD at the frequency extremes of 20 Hz and 20 kHz. Note,
however, that if the power bandwidth
had been limited to from 50 Hz to
10 kHz, amplifier "A" could have well
been rated as a 70- watt -per -channel
amplifier and, with that limitation,
would "read" as the better amplifier
(which in fact, it actually is).
Figure 2 presents a more confusing
situation. The manufacturer of amplifier "B" now chooses to rate his amplifier as a 100 -watt unit-but at a
power bandwidth extending only from
100 Hz to 5 kHz. While more conservative manufacturer `'A" prefers to
provide data on bandwidth from 20

Hz to 20 kHz, and therefore limits

his power rating to 75 watts. Amplifier "A" will probably sound better
when pushed to its power limit, because the low frequency energy demands of music are great, and at 40
Hz, amplifier "A" is actually capable
of audibly greater power output than
amplifier "B ". If this idea is carried
to its ridiculous extreme, there is
nothing to prevent an amplifier manufacturer from specifying power bandwidth from 999 Hz to 1001 Hz so as
to come up with the highest wattage
rating possible (power output at mid frequencies is almost always easier to
achieve than at frequency extremes.
Only an educated consumer could be
expected to understand this subtle
subterfuge and separate the good amplifier from the not -so -good one.
Thus far, we have given examples
of pairs of amplifiers having identical
rated harmonic distortion (THD). In
this area, too, there is unlimited latitude for manufacturers to take. Consider Fig. 3. Amplifier "B" appears to
have greater power output than amplifier "A" and even has great power
bandwidth (20 Hz to 20 kHz against
30 Hz to 20 kHz) but is it, indeed the
"better" amplifier? Its rated distortion
is quoted as 1.0% while that of amplifier "A" is quoted as 0.1 %. If
amplifier "A" were driven harder, so
as to produce the 50 watts shown for
amplifier "B," would its distortion be
AMPL

AMPL A
40

POWER OUTPUT

0.1%

RATED THD
POWER BANDWIDTH

w 80

aZ
p

o
a <

70

50
40
30
20

50
1.0%
20Hz -20 kHz

30Hz -20 kHz

=- '-.
,l

AMPLIFIER

10
1

20

lll
100

llli

500

EA"

AMPLIFIER

1K

"B"-

111111

5K

10K 20K

FREQUENCY (Hz)

FIG.

-SINCE MANUFACTURERS

MAY

QUOTE different rated harmonic distortions

for their products, a fair comparison of these
two amplifiers cannot be made without further information or lab testing.

62
www.americanradiohistory.com

better, equal to, or worse than the 1%

quoted for amplifier "A"? Further,
would its power bandwidth then equal
or exceed the 20 Hz to 20 -kHz bandwidth quoted for amplifier "A "? The
only way a consumer can know would
he to take both amplifiers to a properly equipped laboratory and have
them measured under identical conditions, even though both manufacturers have fully complied with the
new FTC rule.
Pre -conditioning tests
In an attempt to insure that all
amplifier ratings are determined on

the basis of long term operation and

stability of the product being specified, the FTC rule also calls for certain
standard test conditions (120 -volt supply voltage for example) and a one
hour pre-conditioning test during
which the amplifier is required to deliver 1/; of its rated power to a resistive load. Anyone familiar with class
"B" operation of solid state amplifiers
knows that maximum internal power
dissipation of the output transistors
occurs when 40% of maximum power
is delivered to the external loads.
Since 1/3 of full power is very close to
40% of full power, this means that
the output devices will be dissipating
nearly their maximum. Many better
amplifiers are equipped with electronic
protection circuits which would interrupt power under these conditions. In
theory, such amplifiers would have
fulfilled their pre- conditioning tests
even if no power were delivered to
the loads for the last 40 minutes of
the specified hour-though surely the
avowed purpose of the pre- conditioning would not have been fulfilled.
On the other hand, manufacturers
of less sophisticated amplifiers (which
might well destroy themselves or blow
their output fuses during these preconditioning tests) may well have to
derate their stated power output figures or add cost to their products in
the form of larger heat sinks or over
rated power output semiconductors.
This strikes us as unfair to the consumer and the manufacturer. It is well
known that under musical playback
conditions, average power output from
an amplifier (over a long time period)
can be expected to be about 10 -dB
lower than maximum power produced
during moments of loud musical crescendos. Thus, a pre- conditioning test
at 10% of rated power would hrve
been more realistic and more meaningful. Such a 10% pre- conditioning
test was, in fact, called for in the now
obsolete IHF measurement standards.
Other power disclosures
The FTC rule does not specifically
prohibit the publication of power out-

put ratings other than the preferred

"continuous" power. It does, however,
require that such optional disclosures
as "peak power" or "music power" be
accompanied by a disclosure of the
other accompanying parameters such
as impedance and power bandwidth.
Distortion, however, need only be
quoted for the additionally disclosed
rated output (and not all the way
down to 250 mW, as in the case of
continuous power). The FTC further
requires that such optional disclosures
be less conspicuously or prominently
made than the continuous power output disclosure. They go on to define
"less conspicuous as not being in
bold face type nor in type which is
more than two -thirds the height of
the continuous power disclosure. The
advice to the audiophile would seem
to be "Read the large print and ignore
the fine print!"
A

Noble Beginning

Our criticism of the newly issued

FTC power rule should not be taken
as a negative one in all respects. Certainly the need existed for some clarification of this primary specification
as it applies to home audio equipment.
We do, however, take issue with those
who maintain that the new rule in
and of itself, will solve all the problems of misinformation which have
been rampant in the audio industry
for many years. Literature and advertising matter printed by low -end
audio producers of consoles, compacts
and low fidelity components will, no
doubt, have to be dumped in trash
cans (hopefully for paper recycling)
and no doubt these hi -fi opportunists
will henceforth omit all references to
power output rather than he caught
with their one or two watts showing.
Reputable manufacturers of good
quality component equipment will
hardly be affected by the new rule,
since they have generally gone beyond
its disclosure requirements in the past.
The real point to be made is that
the potential audio consumer not be
lulled into a false sense of security
when reading post- November 1974
specification sheets. There can still be
confusion -and you are still not assured of being able to compare products on a totally equal basis. Hopefully, the Institute of High Fidelity
will come up with new Amplifier
Measurement Standards which should
help to make power amplifier specifications more uniform. Until that
happens, it's up to the consumer to
read specs carefully, compare performance through listening tests, and
rely on the hard earned reputation of
legitimate high fidelity component
R -E
manufacturers.

equpmerd
Hewlett- Packard 1221A
and 1220A Oscilloscopes
THE

HEWLETT -PACKARD CO.,

MAKERS

of precision instruments have come up

with a new solid -state triggered -sweep
oscilloscope that should be ideal for
most kinds of electronic work. There
are tw models; the l 221 A singlechannel, and 1220A dual- trace. Otherwise, the two are identical.
The vertical amplifiers have a very
wide response, from dc up to 15 mHz,
at a risetime of 23 ns. The dual -trace
displays in the 1220A use two different modes. The signals are "chopped"
at the lower frequencies, from 0.5
s /div up to 1.0 ms /div. This causes
the sweep to display small sections of
each waveform alternately. While the
beam is traveling from one channel to
the other, it is completely blanked. So
the two waveforms appear to be continuous.
For the higher frequencies, from
0.5 ms /div up to 0.1 ns /div, the
switching goes into an "alternate"
mode. Now, each trace is fully scanned, and the beam then switches to
the other for a full trace.
Each vertical amplifier is identical.
They have calibrated vertical attenuators which cover a range from 2 mv/
div up to 10 V /div in 12 separate
ranges. A variable attenuator can be
used for vernier settings if needed.
Pushbutton selector switches allow a
choice of CHANNEL A, CHANNEL B, or
both at once. The displays are both
locked by the signal in CHANNEL A
for triggering. Since most work involves signals at the same frequency,
one trigger signal can be used for both.
The triggering circuitry will lock in
on any signal from 2 Hz to 15 MHz,
provided the input signal is large
enough to produce one division of
vertical deflection. The trigger action
is very stable and easily adjusted. Internal, external, or ac line sync can be
used by pushing the proper button.
For TV work, the 1220A has an internal TV sync separator. This helps
to lock any standard TV waveform of
either vertical or horizontal frequency.
A slope control allows triggering on

www.americanradiohistory.com

either the positive going or ra gative

going portions of the waveform. Incidentally, the TV sync separator can
be used as a low -pass filter for other
waveform tests, if needed. A iother
pushbutton control allows the 'se of
a fixed attenuator with the ea ternal
trigger signal or external swee3. It has
two positions 1:10 or 1:1.
For use with an external horizontal
sweep signal, the 1220A ci n he
switched to EXT. HOR. input, wh. -n the
x -Y/ SWEEP switch is pushed n the
X-Y position, the internal horizontal
sweep is disabled, and a sweep signal
must be fed into the EXT. HOR. Jack.
This is for use with sweep aligiment
equipment. For vectorscope Js2, the
signal from the red grid can go to the
CHANNEL A input, and from the blue
grid to the EXT.HOR. input
The CRT used in the 122')/. is a
special type. It has the graticile on
the inside of the screen, to e ininate
parallax errors. The phosphor used is
a special P31 type. The trace is blue,
and very bright thanks to the 2 kV
accelerating voltage used.
A BEAM -FINDER pushbutton is used
if there is no trace on the screen This
partially collapses the sweep, showing
you where the pattern is. In adiition
to this, the triggering circuitry has
another very handy feature. Ir stead
of blanking the trace compledely if
there is no input signal. an automatic
circuit causes the trace to appear This
is called the BRIGHT -LINE di:play.
When a signal is applied to th.:. nput,
the bright -line circuitry is autor-atically disabled and the triggerec weep
operates normally.
Despite all of its complex circuitry
the I220A is a very compact instrument. Only 17 cm high, 30.4 cm. wide
and 39;7 cm deep (7 x 12 x 15, in
inches). The controls are very c'early
marked, and the panel is dividec into
sections so that confusion is elirnir ated.
The customary, highly detailec and
well- written instruction book an service manual is provided. This gives
you full instructions for setting up and
operating the 1220A. In addiac n to
this, a very detailed section or the
theory and operation of the it struR -E
ment is included.
s

Step -by-step
TV Troubleshooters Guide
Analyzing output waveforms is an integral part of troubleshooting
a television receiver. This method pinpoints the defective
circuit quickly. Here's a guide to this effective method.
by STAN PRENTISS
WITH

THE

INTRODUCTION

OF

diagram of a color TV receiver, it is

important to look at the set in terms
of functional units rather than limited
stages (see Fig. 1). Using this approach, the overall area of trouble can
be located accurately and quickly, then
conventional methods such as examining individual parts can take over.
With modular and IC receivers this
approach should work, for in some of
these sets selective waveforms will be
either difficult or virtually impossible
to obtain. You should, however, be
very aware of what each waveform
means and why it is there.

BOTH

better instruments and solid -state color

TV receivers, TV waveform analysis
has become a science rather than an
art. And several manufacturers are
already indicating this as they offer
factory-generated keyed rainbow signals for checking overall receiver operation and troubleshooting.
In hybrid and tube sets, marginal
operation is still possible and even
probable if a component is malfunctioning, but solid state receivers either
play or shut down sectionally or completely if a single transistor or IC isn't
doing its job. The reason is that semiconductors normally operate at 90%
of maximum until they either open or
short. Leakage (at least for silicon
types) is usually negligible unless man
made or caused by poor case seals. So,
with RCA announcing no more tube
receivers, and other set manufacturers
probably following, the days of wholesale component substitutions are past,
and an analytical approach to repair
must prevail. Better color bar generators will help make this possible.

Video i.f. amplifiers and agc

As shown in Fig. 2, the upper display (Y1W1) is the total composite
video signal. This signal is composed
of the vertical sync tips (a); blanking
pedestal (b); black peak (c); video
information and white peak (d). Point
d also shows you when the composite
video signal is at full modulation so
the agc may be properly set to avoid
sync compression. The rf agc is adjusted visually (or with a voltmeter)
on weaker signals so that it will become active at some pre- determined
dc level (or i.f. agc's strongest out-

The general approach

When examining an ordinary block
UHF
TUNER

put). It's better of course, to use a

broadcast signal to set the agc than
one from a signal generator since there
is usually more than one station in
each community, and their signal
strengths will normally vary. Using
the composite video signal is also an
excellent way to determine if agc will
drive i.f. amplifiers between cutoff
and saturation; such action is normal
in well -designed sets. In addition, if
the i.f. amplifiers aren't operating
correctly; sync, luminance, and
chroma are all directly affected, as
well as sound. So when servicing a
color receiver, check its general video
response following the video detector;
often your problems begin here and
not where they seem to be. Figure 2
also shows the conventional sync pulse
tip (Y2W1) with the video removed
and a swing of 30 volts p -p. The
waveforms in Fig. 2 consist of slightly
more than one field since each field is
16.664 As in duration, and the scope
time base is set for a total of 20 s

(l O div. X 2As/div.).

Sync pulses
In Fig. 3, all voltages, time base,
and dc references for both waveforms

VHF
TUNER
OR

D.L.

LUMINANCE

I.F. STRIP

AMPLS

VIDEO
DETECTOR -AMPL.

AGC

FROM
HV

)I

HORIZONTAL

GREEN

3.58 mHz

SYNC
SEPARATOR

BURST

AMPL

9
-1

HIGH

DEFLECTION
YOKE

VOLTAGE

-BLOCK DIAGRAM

3.579545 MHz
SUBCARRIER -l75
REGENERATOR

INTE
GRATOR

OSC. -SWEEP

l L

VERTICAL

J
P.

CH ROMA
OUTPUTS

BANDPASS
AMPLS

XTAL

BLUE
CHROMA
DEMOD

RED
REF.

DIFFERENTIATOR

FIG.

OR

RED

BLUE
REF.

OR
OR

-P--

H -V
SWEEP

25kV
TO

Jt_

30kV
FROM SYNC

OR HV

OSC. -SWEEP

OF TYPICAL COLOR TV is the same for tube, transistor or IC circuits.

64

www.americanradiohistory.com

see, sync is transmitted only when

there is no incoming video, so blanking intervals are important too.
The composite video signal is shown
again in Fig. 4 (Y1W3) at a sweep
rate of 10 As /div. The composite
video signal has a blanking interval
(g) of just under 12 As, and a horizontal sync pulse (h) width of 5 ,us.
Note that the sync pulse (h) (Y2W3)
has a sharp leading edge because of

FIG.

2- COMPOSITE

VIDEO and sync wave-

forms.

the instantaneous charge of the differentiator and coupling capacitor, but

the capacitor discharge forms a sloppy
trailing edge. Only the leading edge,
however, is used for the receiver's afc

receiver's blanking circuit bel ore il

reaches the chroma demodulator. In
the chroma -luminance output, therefore, you'll only see 10 cobs bars,
which represent keying of the color
bar oscillator at 30 intervals, producing a rainbow sweep from burst
to 300 , inclusive.
The vertical output pulses l'or all
receivers are somewhat similar, but
there are horizontal drive differences
between tube and solid state receivers.
In the tube receiver, the h.r:izontal
output signal shown in Fig. 6 ('!tfIW5),
measures 250 volts p-p while the vertical output (Y2W5) is almost 1000

FIG.

-A

FAST SWEEP RATE

IE

,ED ta

show the blanking interna' and

ulse.

FIG. 3 -USING THE SCOPE'S X5 EXPANDER shows the intricate details of Fig. 2.

are the same as in Fig. 2, except we're

using the oscilloscope's X5 expander
that produces a sweep of 0.4-ms per
division instead of 2 ms /div. The
blanking interval and sync pulse details now become quite distinct. The
1.4 ms vertical blanking (two fields
to a frame) can now be measured
quite accurately, and the six vertical
pulses (e) are very evident in both
waveforms as are the six equalizing
pulses (f) which precede and succeed them. If this sync information
had been compressed or chstorted, the
deflection circuits would be malfunctioning, especially the vertical oscillator which is often affected first.
Although you won't be expected to
count these vertical sync and equalizing pulses each time there is a sync
problem, it is comforting to know
they're there and not buried somewhere they shouldn't be. As you can

sync time comparison. So there's no

confusion between leading and trailing
edges, let's reverse polarity of the
sweep, and show the trace from left
to right in Fig. 5, rather than vice
versa. What's important about the
waveshapes in Fig. 4 is that both sync
pulses (Y1W3, Y2W3) should have
enough amplitude, duration, and be
of the proper shape, for without all
these your sync problems can be
severe.
Color bar generator substitution
There is only a slight difference in
the waveform's video content as we
substitute a color bar signal, but the
horizontal sync pulse remains the same,
as Fig. 5 shows. The pulses in place
of video in Y1W4 are the 11 color
bars. Bar No. 12 has already been
used by the generator as a sync pulse,
and No. 11 will be removed by the

www.americanradiohistory.com

5-

INTRODUCING THE COI C

FIG.
GENERATOR.

BAP

6-

HORIZONTAL DRIIVE, anc 'rertical

output signals of a tube color set.
FIG.

volts p -p. In addition, although the

vertical waveform is universal tor all
sets, the tube horizontal drive pulse
must be semi -trapezoid (pulse and

sawtooth combined) to drive both inductance and resistance in the yoke

and flyback circuits, while solid -state
versions interface at much lower impedances and may use rectangular
waves with duty cycles of approximately 50 %. Whether trapezoidal or
rectangular, neither waveform drives
the horizontal output for more than
half the total cycle, so that the output
is on for only half the waveform, and
only reaches dc and cutoff at its very
peak.
In RCA's SCR horizontal deflection
drive circuit it's worthwhile looking at
all three drive and output traces (Fig.
7). Here we're dealing with silicon
controlled rectifiers, and when they
conduct, the output voltage drops towards dc. And when they're cut -off
the output voltage rises. Therefore,
the horizontal oscillator trigger (trig,
W6) sends the retrace (comm.
W6) into conduction and it remains
in that state for 25 s. During that interval, the trace SCR cuts off and
stops conducting for about 10 As. The
scope trace then shows that the commutator SCR does not conduct for
some 38 s, making a total horizontal
sweep time of 63.5 s. The trace SCR
(and diode) conducts for a total of
some 53 As.
Chroma circuits
Chroma circuits are no more difficult to analyse than luminance and
sync circuits, but you may not be used
to the clean test patterns on some of
the better sets. In these circuits the
bandpass amplifiers, burst, 3.579545
mHz subcarrier oscillator, and the
chroma -demodulated output are all
needed to complete the analysis. So
with the preset composite video signal
following the video detector, the task
shouldn't be that difficult. Deviations
at this point, however, means there
are specific problems in the receiver
and they should be attended to before

continuing.
Chroma and demodulator outputs
should be examined first, if there is
no color but good black and white.. In
most integrated circuit receivers, luminance information is added either in
the demodulator chip itself (Fig. 1),
or directly into the chroma output

amplifiers. The reasoning here is to

combine luminance information and
chroma (color) information before
the picture tube so both signals can
have identical impedances, proper ac
and dc levels, and be routed to the
picture tube through one set of electrodes. However, you may not see the
red and blue amplifier outputs dis-

FIG.

-RCA's

SCR deflection waveforms.

W7-

R-E's Substitution
guide for
replacement transistors
s

-R -Y

FIG. 8

'x

1OOus.e

PART XXI

/dir

by ROBERT & ELIZABETH SCOTT

AND B-Y OUTPUT and vector

patterns.

1971

edition.

The new edition contains some significant changes, relaxing provisions of

the old Code in some places and tightening them in others. Thus Section
336 -3 (Nonmetallic Sheathed Cable) now

ARCH -Indicates the

Archer brand of
semiconductors sold only by Radio
Shack and Allied Radio stores.
Allied Radio Shack, 2725 W. 7th

W8
DM
G-

St., Ft. Worth, Texas 76107

M. Semiconductor Co., P.O. Box
131, Melrose, Mass. 02176
General Electric Co., Tube Product
Div., Owensboro, Ky. 42301

-D.

E-

ICC- International

x1 lOusec

x2 SOOnsec/div

9-

CHROMA IC AMPLIFIER OUTPUT

FIG.
and subcarrier sinewave.

NEW ELECTRICAL CODE ADOPTED

The National Fire Protection Association adopted the revised and corrected
1975 National Electrical Code as its
standard at its meeting in Miami last
Spring. The new code's publishing date
is September, replacing the present

played as cleanly as those in Fig. 8

(R-YW6 and B -YW6) unless the
luminance signal is shunted to ground
with about an 80 pF capacitor.
Obviously, if you have such waveforms with the red zero reference
voltage at bar six, and the blue zero
reference voltages at bars three and
nine; and plenty of amplitude, your
chroma sections are operating well.
The two 11 -S rectangular pulses cut
off the pix tube during line retrace.
Further confirmation of the chroma
section comes from the two vector
patterns in Fig. 8 (W6) although the
right one is upside down and the
scope's horizontal and vertical polarities must be reversed to turn it right
side up (left vector).
If the chroma outputs are not satisfactory, backtrack to the bandpass
amplifier and see if it has an output
at least in the millivolt range in semiconductor sets, (Fig. 9, top trace) and
in the volt range in hybrid sets. The
bottom trace of Fig. 9 is the output of
the 3.58 -MHz oscillator viewed at 500
S /div. If either the color information
or the subcarrier reference is missing
or is off frequency, then there is no
R -E
demodulation and no color.

permits types NM and NMC cable to be

used in certain types of dwelling and
other structures, and Sections 230 -208
and 240 -100 (Services and Overcurrent
Protection) deletes requirements pertaining to visual current indication. But
Section 300 -15b (Wiring Methods) limits
the use of certain devices without separate boxes. In several sections, some
requirements that had been applied only
where voltages were over 600 are now
general requirements.

66
www.americanradiohistory.com

Components, 10 Daniel
Street, Farmingdale, N.Y. 11735
IR-International Rectifier, Semiconductor
Div., 233 Kansas St., El Segundo,
Calif. 90245
MAL- Mallory Distributor Products Co., 101
S. Parker, Indianapolis, Ind. 46201
MOT -Motorola Semiconductors, Box 2963,
Phoenix, Ariz. 85036
RCA -RCA Electronic Components, Harrison, N.J. 07029
SPR-Sprague Products Co., 65 Marshall
St., North Adams, Mass. 01247
SYL- Sylvania Electric Corp., 100 1st Ave.,
Waltham, Mass. 02154
WOR-Workman Electronic Products, Inc.,
Box 3828, Sarasota, Fla. 33578
ZEN -Zenith Sales Co., 5600 W. Jarvis Ave.,
Chicago, Ill. 60648

Radio -Electronics has done its utmost to

insure that the listings in this directory are as
accurate and reliable as possible; however,
no responsibility is assumed by Radio-Electronics for its use. We have used the latest
manufacturers material available to us and
have asked each manufacturer covered in the
listing to check its accuracy. Where we have
been supplied with corrections, we have updated the listing to include them. The first
part of this Guide appeared in March 1973.

2N4348
2N4349
2N4350
2N4352
2N4354

ARCH

DM

NA
NA
NA
NA
RS276-2021

T-707
TS-3020
TS-3001
T-803
T-708

G-E

ICC

IR

MAL

NA

ICC-707
ICC-S3020
ICC-S3001

IRTR-61
NA
NA
NA
TR-19

PTC 118
PTC 144
NA
NA
PTC 127

GE-28
GE-28
NA
GE-67

CC-803
ICC-708

SPR

SYL

WOR

NA
NA
NA
NA
RT-115

NA
NA
NA
NA
ECG 159

WEP-707
WEP-S3020

SK 3114
SK 3114
NA
NA
HEP-F1035
NA
HEP-803

RT-115
RT-115
NA
NA
NA

EGC 159
ECG 159

WEP-717
WEP-717
WEP-717

MOT

RCA

SK 3079
HEP-707
NA
HEP-S3020
NA
HEP-S3001
NA
HEP-803
HEP-708
SK 3025

NA
NA

NA
NA
NA
NA
ECG 153

NA
WEP-3023
WEP-3023
WEP-3020
WEP-700

NA
NA
NA
NA
NA

NA
RT-131
RT-131

ECG 153
ECG 106
NA
ECG 130
ECG 130

WEP-700
WEP-52
WEP-53
WEP-247
WEP-247

NA
NA
NA
NA
NA

NA
SK 3122
SK 3122
SK 3114
SK 3025

RT-148
RT-102
RT-102
RT-115
RT-115

ECG 180 WEP-WS7001

WEP-735
ECG 123A
WEP-735
ECG 123A
WEP-717
ECG 159
WEP .717
ECG 159

3025
3025
3025
3025
NA

RT-115
RT-115
RT-115
RT-115
RT-114

ECG 129
ECG 129
ECG 129
ECG 129
NA

WEP-242
WEP-242
WEP-242
WEP-242
WEP-712

NA
NA
NA
NA
:-=N 125

GE-67
GE-21
GE-67
NA
NA

ICC-708
ICC-708
ICC-S0006
ICC-F1035
ICC-803

NA
NA
NA

2N4381

T-708
T-708
TS-0006
TF-1035
T-803

2N4382
2N4383
2N4385
2N4386
2N4387

NA
NA
NA
NA
RS276-2025

T-803
TS-3026
TS-3026

NA
NA

GE-63
GE-63
GE-69

ICC-803
ICC-S3026
ICC-S3026
NA
ICC-702

NA
NA
NA
NA
IRTR-58

NA
HEP-803
NA
NA
HEP-S3026
NA
NA
NA
HEP-S3026
NA
NA
PTC 136
SK 3083
HEP-702
PTC 113

NA
NA
NA
NA
RT-133

2N4388
2N4389
2N4390
2N4395
2N4296

RS276-2025

GE-69

ICC-702

NA
GE-27
GE-19
GE-19

ICC-57
ICC-713
ICC-247
ICC-247

IRTR-58
IRTR-54
IRTR-87
IRTR-59
IRTR-59

PTC
PTC
PTC
PTC
PTC

HEP-702
HEP-57
HEP-713
HEP-247
HEP-247

SK 3083
SK 3118
NA
SK 3027
SK 3027

RT-133
RT-126

NA
NA
NA

T-702
T-57
T-713
T-247
T-247

HEP-S7001
HEP-736
HEP-736
HEP-716
HEP-716

NA

NA

T-702

NA

NA

NA

NA

113
103
117
119
119

NA

TS-7001

NA

ICC-S001

TR-20

NA

T-736
T-736
T-716
T-716

GE-20
GE-20
GE-21
GE-21

ICC-736
ICC-736
ICC-716
ICC-716

TR-21
TR-21

2N4402
2N4403

RS276-2009
RS276-2009
RS276-2021
RS276-2021

IRTR-54
IRTR-54

PTC 123
PTC 136
PTC 103
PTC 103

2N4404
2N4405
2N4406
2N4407
2N4409

NA
NA
NA
NA
RS276-2008

TS-3031
TS-3031
TS-3003
TS-3031
TS-0001

NA
NA
NA
NA
GE-18

ICC-S3031
ICC-S3031
ICC-S3003
ICC-S3021
ICC-S0001

IRTR-73
IRTR-88
IRTR-88
IRTR-88
IRTR-87

PTC
PTC
PTC
PTC
PTC

2N4410

RS276-2008

2N4411

NA
NA
NA
NA

TS-0001
T-52
T-51
T-716
T-51

GE-18
NA
GE-67
GE-67
GE-67

ICC-S0001
ICC-52
ICC-51
ICC-716
ICC-51

IRTR-87
TR-20
IRTR-88
TR-20
IRTR-88

PTC 123
PTC 103
PTC 103
PTC 103
PTC 103

T-716
T-802
T-801
TS-0004
T-50

GE-67
GE-FET-2
GE-FET-2
GE-20
GE-20

CC-716

TR-20

ICC-802
NA
ICC-S0004
ICC-50

NA
NA
NA
TR-21

PTC 136
PTC 136
PTC 136

HEP-734
HEP-50
HEP-734

SK 3039

NA
PTC 123

NA
HEP-736

PTC 123
PTC 143
NA
NA
NA

HEP-S3024
HEP-S3008
HEP-S3001
NA
NA

2N4399
2N4400
2N4401

2N4412
2N4413
2N4414

PTC
PTC
PTC
PTC
PTC

3045
3114
3025
3114
3025

RT-110
RT-115
RT-115
RT-115
RT-115

ECG
ECG
ECG
ECG
ECG

154
159
129
159
129

WEP-712
WEP-717
WEP-242
WEP-717
WEP-242

:=N125

2"

=N 107
EN 101

HEP-716
HEP-802
NA

SK
SK
SK
SK
SK

3114
3112
3112
3039
3039

RT-115
RT-176
RT-176
RT-113
RT-113

ECG
ECG
ECG
ECG
ECG

159
133
133
108
108

WEP-717

2'

EN

WEP-801
WEP-801

2=N123

NA

NA
SK 3124

RT-113
RT-113
RT-113
RT-115
TR-102

NA
ECG 123A

SK 3124
SK 3024
NA
NA
NA

RT-102
RT-114
RT-154
RT-154
RT-154

3122
3018
3117
3117
3122

SK 3122
NA

103

T-734
T-50
T/734

GE-20
GE-20
GE-20

ICC-734
ICC/50

NA

GE-21

T-736

GE-20

ICC-52
ICC-736

IRTR-24
TR-21
IRTR-24
NA
TR-21

NA
NA
NA
NA
NA

ts-3024
TS-3008
TS-3001
NA
NA

GE-20
GE-18
GE-28
GE-28
GE-28

ICC-S3024
ICC-S3003
ICC-S3001
NA
NA

NA
IRTR-87
NA
NA
NA

2N4432

NA

T-736

2N4433
2N4434
2N4435
2N4436

RS276-2009

T-734
T-709
T-709
T-736

NA
GE-61

NA
TR-24

GE-17
GE-17
GE-20

ICC-736
ICC-734
ICC-709
ICC-709
ICC-736

2N4437
2N4440

NA
NA
NA

GE-20
GE-28
GEMR-4
GEMR-4
GEMR-4

ICC-736
NA
ICC-R1220
ICC-R1221
ICC-R1222

TR-21
IRTR-55
NA
NA
NA

PTC 136
NA
NA
NA
NA

HEP-736
NA
HEP-R1220
HEP-R1221
HEP-R1222

2N4425
2N4427
2N4428
2N4429
2N4430

NA
NA
NA

T-736
NA

TR-21

IRTR-65
TR-21

PTC
PTC
PTC
PTC
PTC

151

152
133
136

123
132
132
132
123

HEP-S0004
HEP-50

NA
NA
NA
NA
NA

RT-102
RT-108
RT-113
RT-113
RT-102

ECG 123A
ECG 107
ECG 161
ECG 161
ECG 123A

WEP-735
WEP-720
WEP-719
WEP-719
WEP-735

ZEN
ZEN
ZEN
ZEN
ZEN

RT-102
RT-154
NA
NA
NA

ECG 123A
NA
ECG 5442
ECG 5444
ECG 5446

WEP-735
NA
NA
NA
NA

Z:N 120

NA
HEP-R1223
SK 3039
HEP-50
HEP-S0004 SK 3122
NA
HEP-715
HEP-716
SK 3114

NA
RT-113
RT-102
RT-126
RT-115

ECG 5448
ECG 108
ECG 123A
ECG 106
ECG 159

WEP-56
WEP-735
WEP-52
WEP-717

ZEN
ZEN
ZEN
ZEN

RT-126
NA
NA
NA
NA

ECG 106
NA
NA
NA
NA

WEP-52
WEP-310
WEP-310
WEP-310
WEP-241

NA
ZEN 129
ZEN 129
ZEN 129

RT-176
RT-176
RT-176
NA
NA

ECG 133
ECG 133
ECG 133
NA
NA

WEP-801
WEP-801
WEP-801
WEP-310
WEP-310

NA

HEP-736
HEP-734
HEP-709
HEP-709
HEP-736

SK
SK
SK
SK
SK

NA

2N4444
2N4449
2N4450
2N4451
2N4452

NA
NA
NA
NA
NA

SR-1223
T-50
TS-0004
T-715
T-716

NA
NA
NA
NA
NA

ICC-R1223
ICC-50
ICC-S0004
ICC-715
ICC-716

NA
NA
NA
NA

NA
PTC 133
PTC 136
PTC 127
PTC 103

2N4453

NA

RS276-2029
RS276-2029
RS276-2029

T-76
T-310
T-310
T-310

NA

t-241

NA
NA
NA
NA
NA

ICC-76
ICC-310
ICC-310
ICC-310
ICC-241

NA
NA
NA
NA
NA

PTC 127
NA
NA
NA
NA

HEP-76
HEP-310
HEP-310
HEP-310
HEP-241

SK 3118

2N4851

NA
NA
NA
RS276-2029

NA
NA
NA
T-310

NA
NA
NA

PTC 152
PTC 152
PTC 152
NA
NA

SK 3112
SK 3112
SK 3112
NA

T-310

NA
NA
NA
NA
NA

NA
NA
NA
HEP-310

RS276-2029

GE-FET-1
GE-FET-1
GE-FET-1
NA
NA

HEP-310

NA

CC-310
CC-310

NA
127
.[ EN 100
EN

WEP-735
WEP-243

NA

2N4867
2N4868
2N4869
2N4870
2N4871

107

ECG 192
ECG 128
NA
NA
NA

NA

NA

2N4852
2N4853
2N4864

27

Z=N118

2N4442
2N4443

NA

WEP-56
WEP-56

NA

..=N 101

WEP-723
WEP-50
WEP-723
WEP-717
WEP-735

SR-1220
SR-1221
SR-1222

2N4441

EN 107

ZEN 107

SK
SK
SK
SK
SK

NA
NA
NA
NA
NA

2N4424

HEP-S0001
HEP-52
HEP-51
HEP-716
HEP-51

2N4420

CC-734

NA
ZEN 120
ZEN 120

SK
SK
SK
SK

NA
NA
NA
NA

2N4421
2N4422
2N4423

NA
NA
NA

HEP-S3031
HEP-S3031
HEP-S3003
HEP-S3031
123 HEP-S0001

141
141
141
141

2N4415
2N4416
2N4417
2N4418
2N4419

NA

WEP-717

EN 204
NA
NA
NA
NA
NA
NA
NA
NA
NA

HEP-708
PTC 127
HEP-708
PTC 103
PTC 127 HEP-S0006

RS276-2021
RS276-2021
NA
NA
NA

2N4355
2N4356
2N4359
2N4360

NA
NA

ZEN

NA
NA

NA
NA
NA
NA

NA
NA

NA

NA
NA
NA

NA
2 EN 120

120
118
105
105
120

NA
NA
NA
NA
NA
100
127
106
107

NA

NA
NIA

NA
129
ZE V 129
ZE NJ

Pur,'.

NA =NOT APPLICABLE

100

EN

?_N118

nage)

67
www.americanradiohistory.com

ARCH

DM

G -E

ICC

MAL

IR

MOT

2N4872
2N4873
2N4874
2N4875
2N4876

NA
NA
NA
NA
NA

T-52
TS-0004
TS-3008
TS-3008
TS-3008

NA
NA
NA
NA
NA

ICC-52
ICC-S0004
ICC-S3008
ICC-S3008
ICC-S3008

NA
NA
NA
NA
NA

PTC
PTC
PTC
PTC
PTC

2N4877
2N4878'
2N4879*
2N4880'
2N4890

NA
NA
NA
NA
NA

TS-3010
T-738
TS-0007
T-729
T-708

GE-66

ICC-S3010
ICC-738
ICC-S0007
ICC-729
ICC-708

NA
NA
NA
NA
NA

NA
HEP-S3010
PTC 123
HEP-738
PTC 144 HEP-S0007
PTC 121
HEP-729
PTC 141
HEP-708

2N4891

NA
NA
NA
NA

T-310
T-310
T-310
T-310
T-702

NA
NA

ICC-310
ICC-310
ICC-310
ICC-310
ICC-702

NA
NA
NA
NA

NA
NA
NA
NA
PTC 113

2N4892
2N4893
2N4894
2N4898
2N4899
2N4900

RS276-2025

2N4901

RS276-2025
RS276-2025
RS276-2027

2N4902
2N4903

NA
NA

2N4904
2N4905
2N4906
2N4907
2N4908

RS276-2027

2N4909
2N4910
2N4911
2N4912
2N4913

2N4914
2N4915
2N4916
2N4917
2N4918

NA
NA
NA
NA
NA

RS276-2017
RS276-2017
RS276-2017
NA
NA
NA

RS276-2023
RS276-2023
RS276-2027

NA
NA
NA

GE-67

NA
NA

GE-69

T-702
T-702
T-705
T-248
TS-5005

GE-69

T-705
T-248
T-248
T-248
T-248
TS-5005
T-703
T-703
T-703
T-247

GE-66
GE-66
GE-32
GE-19

IRTR-58

ICC-702
ICC-702
ICC-705
ICC-248
ICC-S5005

IRTR-58
IRTR-58
TR-29
TR-29

NA
NA
NA
NA

ICC-705

NA

ICC-248

TR-29
TR-29
NA
NA
NA

NA

ICC-S5005
ICC-703
ICC-703

NA
NA
NA
NA

T-247
T-247
T-52
T-52
T-700

GE-19
GE-14
GE-22

CC-248
ICC-248

CC-248

CC-703
ICC-247

ICC-247
ICC-247
ICC-52

NA

127
133
143
143
143

HEP-52
SK 3118
HEP-S0004 SK 3039
HEP-S3008
NA
HEP-S3008
NA
HEP-S3008
NA

HEP-310
HEP-310
HEP-310
HEP-310
HEP-702

PTC 113
HEP-702
PTC 113
HEP-702
NA
HEP-705
NA
HEP-248
NA
HEP-S5005
NA
NA
NA
NA
NA

RCA

NA

WOR

RT-126
RT-113
NA
NA
NA

ECG 106
ECG 108
NA
NA
NA

RT-150
RT-109

WEP-728
WEP-712
WEP-729
WEP-242

WEP-52
WEP-56
NA
NA
NA

ZEN
NA
ZEN 127
NA
NA
NA

NA

NA

NA

RT-109
RT-115

NA
NA
NA
NA
ECG 129

NA
NA
NA
NA
RT-133

NA
NA
NA
NA
ECG 218

WEP-310
WEP-310
WEP-310
WEP-310
WEP-700

ZEN 129
ZEN 129
ZEN 129
ZEN 129
NA

NA

RT-133
RT-133
NA
NA
NA

ECG 218
ECG 218
NA
NA
NA

WEP-700
WEP-700
WEP-S7001
WEP-S7001
WEP-S5005

NA
NA
NA
NA
NA

NA
NA
NA
NA
NA

NA
NA
NA
NA
NA

NA
NA
NA
NA
NA

WEP-S7001
WEP-S7001
WEP-S7001
WEP-S7001
WEP-S7001

NA
NA
NA
NA
NA

WEP-S5005
WEP-241
WEP-241
WEP-241
WEP-247

NA
NA
NA
NA
NA

NA

NA
NA
NA
NA

NA
SK 3083
SK 3083
NA
NA

NA

HEP-705
HEP-248
HEP-248
HEP-248
HEP-248

SYL

SPR

NA

ZEN 207
ZEN 121
NA
ZEN 115
NA

NA
NA
NA
NA
TR-59

NA
HEP-S5005
PTC 112
HEP-703
PTC 112
HEP-703
PTC 112
HEP-703
PTC 118
HEP-247

SK
SK
SK
SK

NA
3131
3131
3131
3027

NA
RT-150
RT-150
RT-150
RT-131

NA
ECG 175
ECG 175
ECG 175
ECG 130

TR-59

HEP-247
HEP-247
HEP-52
HEP-52
HEP-700

SK 3027
SK 3027
SK 3025
SK3114
NA

RT-131
RT-131
RT-115

RT-115
RT-153

ECG
ECG
ECG
ECG
ECG

130
130
159
159
185

WEP-247
WEP-247
WEP-717
WEP-717
WEP-WS5007

NA
NA
NA
NA
NA

HEP -246
HEP -S5006
HEP -245
HEP -245
HEP -245

NA
NA
NA
SK 3054
NA

RT -153
RT -153
RT -152
RT -152
RT -152

ECG
ECG
ECG
ECG
ECG

185
185
184
184
184

WEP- WS5007
WEP- WS5007
WEP- WS5003
WEP- WS5003
WEP- WS5003

ZEN 203
NA
ZEN 202
ZEN 202
ZEN 202

3045
3045
3045
3045
3025

RT -110
RT -110

RT -110
RT -110
RT -115

ECG
ECG
ECG
ECG
ECG

154
154
154
154
129

WEP -712
WEP -712
WEP -712
WEP -712
WEP -242

NA
ZEN 205
ZEN 205
ZEN 205
NA

NA

GE-21

CC-52

GE-29

ICC-700

NA
NA

PTC 118
PTC 118
PTC 103
PTC 103
NA

NA

TR-20

2N4919
2N4920
2N4921
2N4922
2N4923

RS276-2018
RS276-2018
RS276-2018

T-246
TS-5006
T-245
T-245
T-245

GE -29
GE -69
GE -28
GE -28
GE -28

ICC -246
ICC -S5006
ICC -245
ICC -245
ICC -245

IRTR -77
NA
NA
NA
NA

NA
NA
PTC 110
PTC 110
PTC 110

2N4924
2N4925
2N4926
2N4927
2N4928

NA
NA
NA
NA
NA

T -713
T-712
T -712
T-712
T-710

GE -27
GE -32
GE -27
GE -27
NA

ICC -713
ICC -712
ICC -712
ICC-712
NA

NA
IRTR -78
IRTR -78
IRTR -78
IRTR -88

PTC
PTC
PTC
PTC
PTC

144
117
117
117
127

HEP -713
HEP -712
HEP -712

HEP -712
NA

SK
SK
SK
SK
SK

2N4932
2N4934
2N4935
2N4936
2N4937*

NA
RS276-2011
RS276-2011
NA
NA

NA

T-56
T-56
T-56
T-715

NA
NA
NA
NA
GE-21

NA
ICC-56
ICC-56
ICC-738
ICC-715

NA
IRTR-66
NA
NA
NA

PTC
PTC
PTC
PTC
PTC

128
133
133
133
127

NA
HEP-56
HEP-56
NA
HEP-715

NA
SK 3039
SK 3039
SK 3039
NA

NA
RT-113
RT-113
RT-113
RT-115

NA
ECG 108
ECG 108
ECG 108
NA

WEP-56
WEP-56
WEP-56
WEP-715

NA
ZEN 104
ZEN 104
ZEN 121
ZEN 106

2N4938'
2N4939*
2N4940'
2N4941'
2N4942*

NA
NA
NA
NA
NA

T-715
T-715
T-715
T-715
T-715

GE-21
NA
GE-21
GE-21
NA

ICC-715
ICC-715
ICC-715
ICC-715
ICC-715

NA
NA
NA
NA
NA

PTC
PTC
PTC
PTC
PTC

127
127
127
127
127

HEP-715
HEP-715
HEP-715
HEP-715
HEP-715

NA
NA
NA
NA
NA

RT-115
RT-115
RT-115
RT-115
RT-115

NA
NA
NA
NA
NA

WEP-715
WEP-715
WEP-715
WEP-715
WEP-715

ZEN
ZEN
ZEN
ZEN
ZEN

2N4943
2N4944
2N4945
2N4946
2N4948

NA
NA
NA
NA
NA

T-714
T-714
T-714
T-714
T-310

NA

ICC-714
NA
NA
ICC-714
ICC-310

IRTR-87
IRTR-87
IRTR-87
IRTR-87
NA

PTC 144
PTC 123
PTC 123
PTC 123
NA

HEP-714

GE-20
GE-18
GE-20

3024
3024
3024
3024
NA

RT-114
RT-114
RT-114
RT-114

2N4949
2N4950

NA
NA
NA
NA
NA

T-310

ICC-310

TS-0004
TS-0004
T-736

NA
NA
NA
NA

NA
NA
NA
NA
NA

TS-0004
T-737
T-724
TS-3001
TS-3002

2N4951

2N4952
2N4953
2N4954
2N4955
2N4956'
2N4960
2N4961

RS276-2026
NA

NA

NA
NA
GE-20
GE-20
GE-20
GE-10

GE-10
NA
NA
NA
NA

NA

ICC-S0004
ICC-S0004
ICC-736
ICC-S0004
ICC-737
ICC-724
ICC-S3001
ICC-S3002

TR-2

TR-2
NA
NA
IRTR-87

IRTR-87

NA
NA

HEP-714
HEP-310

SK
SK
SK
SK

NA
HEP-310
NA
NA
PTC 136 HEP-S0004
PTC 136 HEP-S0004
PTC 136
HEP-736

NA
NA
SK 3124
SK 3124
SK 3124

PTC 136
NA
PTC 121
PTC 123
PTC 123

SK 3124
NA

'Indicates a dual tran sistor for high -speed switching, diff amplifier etc. Likely to be
curve tracer or lab -type transistor checker.

HEP-S0004
HEP-737
HEP-724
HEP-S3001
HEP-S3002

NA
SK3024
SK 3024

ECG
ECG
ECG
ECG

106
106

106
106
106

NA

128
128
128
128
NA

WEP-243
WEP-243
WEP-243
WEP-243
WEP-310

NA

NA
NA
ECG 123A
ECG 123A

RT-102

ECG 123A

WEP-310
NA
WEP-735
WEP-735
WEP-735

ZEN 129

NA
RT-102
RT-102

RT-102
RT-109
RT-105
RT-114
RT-114

ECG 123A
NA
NA
ECG 128
ECG 128

WEP-735
WEP-735
NA
WEP-243
WEP-243

ZEN 127
NA
ZEN 112
NA
NA

NA
NA

NA
NA

ZEN 129

NA
ZEN 127
ZEN 127
ZEN 120

matched pair. Use two of the type specified, matching when necessary, on a

NA- NOT AVAILABLE

(continued next month)

www.americanradiohistory.com

ON -

RE's Service Clinic

networks and
different waveforms
RC

The effects are weird if you

don't know what to expect

from a function generator; sine, square

and triangular waveforms. I fed these
through the two stock R -C network
hook -ups; a differentiator and a n integrator. A quick look at the s.hematic
of any kind of electronic equ pment
will show you lots of these thin s.
Figure
shows the circuits used.
Look at these. Now, draw yob r idea
of what the output waveform looks
like, and see if you can explain it.
After you get through, read cn and
see what I actually got, and n'y idea
of why. Have fun!

WHILE WORKING IN MY LABORATORY

recently, doing research on the behaviour of special test signals. (Translation; I was goofing off in the shop,
playing with a function generator!) I
ran across some interesting things.
SIG -GEN

OUTPUT

.._A

SCOPE

VERTICAL
INPUT

.01

1.5K

COMMON

by JACK DARR

DIFFERENTIATOR

SERVICE EDITOR

OUTPUT

The answers.
Figure 2 shows the input, 'o the
differentiator circuit and th. 3utput

SCOPE

SIG -GEN

VERTICAL
INPUT

1.5K

waveforms I saw on the scope

1. Almost everybody should
one, or get close. The diffee
makes a spike waveform from a
wave. This is used in mar
generator circuits.

T.01

COMMON

INTEGRATOR

FIG.1
f

DI

3 kHz

et this

Itiator
square

pulse

FFERENTIATOR

INPUT

OUTPUT

--k17-L

This column is for your service

problems-TV, radio, audio or general
and industrial electronics. We answer
all questions individually by mail, free
of charge and the more interesting ones
will be printed here.
If you're really stuck, write us. We'll
do our best to help you. Don't forget to
enclose a stamped, self- addressed envelope. If return postage is not included, we cannot process your question.
Write: Service Editor, Radio- Electronics, 200 Park Ave. South, N.Y. 10003.

FIG. 2

They interested me, anyhow. I knew

that you'd change a waveform if you
fed it through an R -C network. However, I got one result that wiped me
out. After a lot of digging, I found out
why. See if you can predict the results,
and then explain 'em.
I used the three standard signals

2. This one fooled me. Hoy /ever,

you can see what happened. The time
constant is long enough so the t the
capacitor reaches full charge. '>o, it
rounds off the leading edge of the
square wave.
3. This is the wipe -out. What hap -

pended? Nothing. Output

WE VI

form

69
www.americanradiohistory.com

exactly the same as the input! We'll

explain that in a minute. Go on to
Figure 3. This is the integrator.
4. Surprise! An integrator makes a
triangular wave out of a square wave.
This is used in function generators to
develop a triangular wave.
5. Look at this one. Integrating a
triangular wave makes a sinewave.
Another method used in function
generators, although theirs is much
f

more elaborate.
6. Here we go again. Nothing happens, just as before.

after quite a bit of digging

around.
As briefly as possible, both square
and triangular waves can be considered
as being made up of innumerable
harmonics! The charging of the
capacitor and the action of the resistor
affects these; the waveform is distorted, although its fundamental frequency is still the same.
The really odd effect is the reaction
on the sinewave. Why doesn't the R-C
network upset it, as it does all others?
Here's what they say.
A sinewave, especially one with very
low distortion, is considered as a "pure
signal." That is, it's not made up of
harmonics, but is just a single frequency, theoretically without any harmonics at all! So, you'll see practically
no effect on the waveform. Most of
what you will see will be only a small
loss in amplitude.
You can try this yourself, with any
audio signal generator and scope. It's
fascinating. Try different values for R
and C, and different frequencies. If
you don't have a square -wave signal
generator, feed the sinewave output
into a pair of low-voltage Zeners, tied
in parallel and reversed. This will
make a fair square wave. You can get
the triangle by feeding the square
wave into a separate integrator, and
then feeding the resultant into another
R -C network. (continued on page 72)
find,

Wha' Happen?
How come this reaction? Frankly,
expected to see a change in waveform in all of them. When the sinewave came through undisturbed, I
couldn't believe it. Back to the books.
Here is the best explanation I could
I

INTEGRATOR

30 kHz
INPUT

OUTPUT

FIG. 3

RCA's versatile WO-535A.

DC tolOMHz response for only $349.'

cc

a
cc

70

1.Operates in either triggered

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11. Terminals

for direct connection to the CRT.

12. Camera mounting studs.
13. Phase control for sweep
alignment.
14.Includes WG -400A
shielded Direct/LowCapacitance Probe and
Cable.
For complete information and
fast delivery on the versatile
WO -535A, Dual Mode Oscilloscope, contact any one of
the more than 1,000 RCA Distributors worldwide. Or write:
RCA Electronic Instruments
Headquarters, Harrison, N.J.
07029.

'Optional price including probe.

RC,'

Specialists demand the best tools of their trade

Electronic
Instruments

Circle 17 on reader service card

www.americanradiohistory.com

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71

SERVICE CLINIC
(continued from page 70)

Now -the handiest book

on electronics you'll ever ownVEST PCC ET

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questions

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Reference Book

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Remy rhama

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Circle 19 on reader service card

www.americanradiohistory.com

Originally, this Motorola TS -914

chassis came in with the circuitbreaker tripping. Replaced a bad
diode in the voltage-doubler -no
help. The resistor in parallel with
the degausser coil was open and
replaced it When I turned the set
on, there was a spark from somewhere. After this the breaker
didn't trip any more.
The purity is lousy. The best I
can get is a 12 -inch red circle in
the middle with blotches around
the edge. I cooked it for 6 hours.
While this was going on, I noticed
that the purity began to get worse
around the edges. Manual degaussing will clear it up, but it comes
back in a few hours.
I'm at a loss. HELP! -D.S. Oregon, OH.
The trouble is in the auto degausser circuit. It is obviously "re -gaussing" the tube! In this chassis, the
most likely suspect would be the thermal degaussing switch. This could
have been where your arc was. If the
points have welded, this leaves the
coil in- circuit all the time, and this
causes impurity.
NO SNOW, THAT'S BAD

This Sylvania DO3 has been

pretty well overhauled; tuner, new
filters and so on. I'm still not happy with it. The agc control doesn't
have the proper effect. Also, I have
no snow on unused channels, nor
with the antenna off. Distant stations won't come in, though the
owner says they used to. Colors
aren't good, even on local stations.
What do you think ? -R.D., Panama
City, FL.
I think you're "losing it," somewhere. This set obviously doesn't have
enough gain. The no -snow symptom is
almost always an indication of very
poor rf or i.f. gain. This could he due
to one of two things.
Excessive negative agc voltage could
be holding the gain down. This is the
easy one. Clamp the agc to +18 volts.
If this sounds funny in a tube set,
remember that the 1st i.f. cathode is
+21 volts above ground so that the
actual agc bias on the tube is a -3
volts. If this brings the snow and the
colors back, check out the dc voltages

(continued on page 78)

Our town
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73

CIE

graduate builds

two -way radio

service business

into $1 ,000,000
electronics company!
How about YOU? Growth of two -way

transmitters creates demand for

new servicemen, field and system
troubleshooters. Licensed experts
can make big money. Be your own

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don't need

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Two -way radio is booming. There are already nearly

seven million two -way transmitters for police cars, fire
department vehicles, taxis, trucks, boats, planes, etc.,
and Citizens Band uses. And the number keeps growing
by the thousands every month. Who is going to service
them? You can if you've got the know -how!

Why You'll Earn Top Pay

One reason is that the United States Government doesn't
permit anyone to service two-way radio systems unless
he's licensed by the FCC (Federal Communications
Commission).
Another reason is that when two -way radio men are
needed, they're really needed! A two -way radio user
must keep those transmitters operating at all times. And,
they must have their frequency modulation and plate
power input checked at regular intervals by licensed
personnel to meet FCC requirements.
As a licensed man, working by the hour, you would
usually charge at least $5.00 per hour, $7.50 on evenings and Sundays, plus travel expenses.
Or you could set up a regular monthly retainer fee
with each customer. Your fixed charge might be $20 a
month for the base station and $7.50 for each mobile
station. Studies show that one man can easily maintain
at least 135 stations averaging 15 base stations with 120
mobiles! This would add up to at least $12,000 a year.

Edward J. Dulaney, Scottsbluff, Nebraska, (above and at right)

earned his CIE Diploma in 1961, got his FCC License and moved
from TV repairman to lab technician to radio station Chief
Engineer. He then founded his own two-way radio business.
Now, Mr. Dulaney is also President of D & A Manufacturing,
Inc., a $1,000,000 company building and distributing two -way
radio equipment of his own design. Several of his 25 employees
are taking CIE courses. He says: "While studying with CIE, I
learned the electronics theories that made my present

business possible."

Be Your Own Boss

There are other advantages, too. You can become your
own boss work entirely by yourself or gradually build
your own fully staffed service company. Of course, we
can't promise that you will be as successful as Ed
Dulaney, or guarantee that you'll establish a successful
two -way radio business of your own, but the opportunities for success are available to qualified, licensed men
in this expanding field.

How To Get Started

How do you break in? This is probably the best way:
1. Without quitting your present job, learn enough about
electronics fundamentals to pass the Government
FCC exam and get your Commercial FCC License.
2. Then get a job in a two-way radio service shop and
"learn the ropes" of the business.
3. As soon as you've earned a reputation as an expert,
there are several ways you can go. You can move
out and start signing up and servicing your own customers. You might become a franchised service representative of a big manufacturer and then start getting
into two -way radio sales.
Cleveland Institute of Electronics has been successfully
teaching Electronics for over 37 years. Right at home, in
your spare time, you learn Electronics step by step.

74
www.americanradiohistory.com

CIE's AUTO-PROGRAMMED Lessons remove the

roadblocks by using simple, concise examples. You learn
in small, compact steps each one building on the other!
You'll learn not only the fundamentals that apply to
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All CIE career courses are approved for educational
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You Get Your FCC License...

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By the time you've finished your CIE course, you'll be
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you complete any CIE licensing course, you'll be able to
pass your FCC exam or be entitled to a full refund of all
tuition paid. This warranty is valid during the completion
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or your money back!

Cleveland Institute
of Electronics, Inc.

1776 East 17th Street, Cleveland, Ohio 44114

Accredited Member National Home Study Council
Please send me your two FREE books:
1. Your book on "How To Get A Commercial FCC License."
2. Your school catalog, "Succeed in Electronics."
I

am especially interested in:

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Electronics Technology
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Name

It's Up To You
Mail the reply card for two FREE books, "Succeed in
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1776 E. 17th St., Cleveland, Ohio 44114.

(Please Print)

Address
City
State

Zip

Veterans & Servicemen: Check here for

Circle 21 on reader service card

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G. I.

AgeBill informativ
RE

77

SERVICE CLINIC

(continued from page 72)

around the agc tube. Remember that

the schematic voltages are read with
no signal. These are all critical voltages.

Second possibility is a problem of

low gain in either the rf amplifier or
possibly the 1st or 2nd video i.f. stages.
Check all dc voltages and the tubes,
etc.
While you're there, check the 5.6megohm resistor from the rf agc terminal to +265 volts. This is supposed
to provide a small positive voltage to
keep the agc from going too far negative. If it's open, you'll often get the
type of symptom you have.
G -E MI1OYBG HINT
On the G -E M1 1 OYBG and other
SY chassis models, they use a copper
strip bolted to the top front horizontal
bar of the chassis as the ground for
the Aquadag coating on the picture
tube. If the Aquadag burns off or has
poor contact here, it will arc. This will
radiate and mess up the horizontal
sync. Fix this ground. Use a spring, or
another thin strip like that used to
ground the tuner. I've done this on
several of these sets.
Thanks very much to Paul Fleming
of Dallas, Texas for this one.
R -E

APPLIANCE CLINIC
(continued from page 24)

covered, this should read approximately 15,000 ohms or more. Now

uncover the cell and let light hit it.
The resistance should drop to somewhere around 1500 to 2000 ohms.
The higher the intensity of the light,
the lower the resistance. The relay
should now close if power is applied
to the unit. If it won't move, turn the
power off and connect a jumper clip
lead across the photocell. The armature should now close unless the coil
has some shorted turns.
Figure 2 shows the schematic of a
larger unit, used with the mercuryvapor lamps. Note the similarity. This
one has a temperature- sensitive resistor mounted in shunt with the photocell and coil. Some units have a
sensitivity control, so the lamp can be
turned on at any desired level of outside light. (Some of these can be so
sensitive that they turn on when the
weather is fairly cloudy!)
The control unit in Fig.
is practically instantaneous. With the larger
units in Fig. 2 and mercury -vapor
lamps, there will be about one or two
second delay. This isn't due to the
control unit but rather the characteristics of a mercury-vapor lamp. These
are actually "arc lamps," and it takes
1

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signal generator.

Except a high price.

Our new B &K Model 2050 Solid -state RF Signal
Generator has features other companies charge
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Contact your distributor, or write Dynascan
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a little time for the arc to form.

This delay will be almost impossible

to notice during normal operation.
However, during a violent thunderstorm with its associated bright flashes
of lightning, you may notice the lamp
going off. It may stay off for a moment,
especially after a very bright flash. The
photocells in this case are said to be
temporarily "blocked". This is caused
by very high- intensity light, just as
human vision is temporarily blinded.
This won't do any permanent damage,
unless of course the unit takes a direct
lightning hit.
R -E

Introducing the B &K Model 290 solid -state FET

Multimeter. Just by glancing at its specs, you can
tell that the 290 is capable of more applications
than any other multimeter in its class. 75 ranges.
Hi -Lo power ohms ranges (low power only 33 mV).
15 megohms input impedance. A large 7 "meter.
50 mV to 1500V full -scale sensitivity on both AC
and DC. 50 micro -amp current range. Rx0.1 ohm
range with 1 ohm center scale lets you measure
low resistance down to .01 ohm. Circuit provides
automatic overload protection with fuses and spark
gaps. More multimeter for your money that's
just what you expect

from B &K.

--Y

Dynascan Corporation.

FIG. 2

Here's everything
you'd expect from a high -priced
Hi -Low FET multimeter.
Except a high price.

$10700

Very good equipment at a very good price.

MERCURY
VAPOR LAMP

Contact your
distributor, or write
Dynascan Corporation.
Model 290 Hi -Low
FET Multimeter ineluding Model PR -21
Probe:

$15100

Very good equipment at a very good price.

Belle Plaine Avenue, Chicago, Illinois 60613

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Circle 23 on reader service card

Circle 22 on reader service card

www.americanradiohistory.com

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www.americanradiohistory.com

BUILD A PHOTOFLASH
(continued from page 37)

the recycle power to build -up. Then

re- trigger the unit for approximately
30 flashes. The combination of 3 hour
charge and repeated flashing will complete the forming operation and the
flash unit will be ready to use with
your camera.
Always trigger your flash unit several times before beginning to take
pictures to assure maximum power
output. Unused units will gradually
de -form with age, and it is recommended that the forming operation be
followed once every two to three
months for better operation and to
extend the life of the capacitors.

Series capacitor bank

forming operation
Plug in the ac power line and turn
the power switch to ON. Before triggering the photoflash unit, allow the
unit to charge for no less than three
hours, overnight is even better.
After the minimum charging period,
or overnight, attach a camera sync
cord to the camera sync socket and
with a pin or small piece of wire,
short the end terminals to trigger the
flash. Then allow 3 to 7 seconds for

Operation
Bare -bulb operation, without a reflector, usually has a guide number of
30 for a 200 watt -second power output, and as high as 150 with reflector
for ASA 25 film. Guide numbers are
just that ... a guide to use as a starting point for proper exposure. I recommend running a test film of varied
exposures and shutter speeds to determine the proper guide number for
your type of use. This involves shooting a series of pictures on a good
resolution film, one rated at ASA 30
to ASA 65. Bracket your exposures
4 stops up and 4 stops down from
f -8 at a shutter speed of Moo-second.

Always use a maximum shutter

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shutter setting.

Troubleshooting the
photoflash unit.
If you have properly made the circuit boards and installed each component properly, there should be no
difficulty encountered in operating the
unit. Usually, during the initial forming operation, considerable heat will
be radiated from R1, and the possibility of the fuse blowing exists. This
can be caused by excessive leakage of
capacitors C3 and C4 that will correct its -self after completing the forming operation. It can also be caused
by connecting the polarity of the capacitors incorrectly. Should your fuse
blow, check the capacitor polarity
FIRST.
Should the flash tube fail to fire,
remove the flash tube from it's socket
and measure across the socket pins
with a DC Voltmeter. The positive
lead of the voltmeter to pin 2 and
the negative lead to pin 4. It should
measure 450 volts. Should you be
unable to measure the voltage; turn
off power switch, open top, and check
the following:
check
check 2
check 3
1

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Circle 25 on reader service card

www.americanradiohistory.com

check 4

check

check 6

Open fuse
Open R1
Incorrect polarity of capacitors C3 and C4
Open or shorted D1, D2,
D3
Incorrect polarity of capacitors C 1 or C2
Open connection between
power circuit and trigger
circuit

For those who would like to construct a bare bulb electronic photoflash
unit but would prefer to assemble a
kit, there is a kit for the Uniflash
barebulb photoflash produced by
Mitchell Enterprises, P.O. Box 1372,
R-E
San Francisco, CA. 94101.

NEW IN DVM's
(continued from page 49)

2,

COLD -CATHODE DISPLAY TUBES and

other similar lamps indicate voltage,
current and resistance measurements on
the Heathkit model IM -102 31/2 -digit
dmm, Most voltage and current ranges
have overrange capability and an over range indicator is provided. Polarity of
dc voltage and current is automatically
detected and displayed. Decimal -point
positioning is automatic on each range.
Dc voltage ranges are 200 mV, 2, 20,
200 and 1000 volts. Input impedance is
greater than 100 megs on the first range,
greater than 1000 megs on the second
and 10 megs on the 20, 200 and 1000 volt ranges. Accuracy is 0.2% 1
digit. Overrange capability 20 % -subject to overload protection limits. Resolution (200-mV range) is 100 V.

-+-1

digit on dc, 1.0% 1 digit

on ac.
The 1M -102 is 3
$239.95.

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AUTO -RANGING AND

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6 W. It is 31/2 x 91/4 x 103/4 in., 11/2 lbs.
$299, $359 with rechargeabl? battery

in., 4 lbs.

pack installed.
ONE -YEAR BATTERY LIFE frc n a standard 9 -volt transistor battery anc liquid crystal display are two novel fosa ures of
Danameter model 2000, a p.o :uct of
Dana Laboratories.

LOW -POWER

OHMS are but two of the features of the

Keithley model 168 dmm. The five functions give you the capabilty of measur-

Ac voltage ranges same as dc; input

impedance is 1 megohm / 150 pF. Overload protection 250 Vrms on lowest two
ranges; 500 Vrms on the top three. Accuracy ranges from 0.75% 1 digit
to 1.5% 1 digit.
Current ranges (dc and ac): 200 AA,

KICK

This dmm operates from 90-113, 105-

20 and 200 mA and 2 A. Accuracy

0.3%

ing 100 AV to 1000 Vdc, 100 AV to 500

Vac, 100 nA to 1 amp ac and dc and
100 milliohms to 20 megohms. Input
resistance is 10 megs on dc and 9 megs
shunted by 90 pF on ac.
The 168 may be powered by line voltage or rechargeable NiCad batteries
when the model 1688 rechargeable battery set is installed.
With this dmm, you can turn on a
semiconductor junction to see if it is
good; or measure resistance in- circuit

Voltage ranges (ac and dc) are 2, 20,

1
kV with 1 mV resalu on. Input impedance is 10 megohrns on dc
and 2 megs shunted by 40 pF on ac.
Accuracy is 0.5% of reading +.05%
of range on 2 -volt dc range; _ 0 75% of
reading +.05% of range on tte -emain200 and

without turning on associated semiconductors. The 1.8 volts across the test

ing dc ranges.

Direct current ranges are 2) A, 200

2 A with 0.01 AA ,er olution.
Resistances ranging from 20C trims to
200 megohms are covered in air 100:1
h -i. The
ranges. Resolution is 0.1
R -E
Danameter 2000 is $195.

prods, in the HIGH -OHMS mode, is

enough to turn on most semiconductors.
In the LOW -OHMS mode, a maximum of
180 mV is applied to the circuit under
test so semiconductors are not turned

mA and

on.

UT THOSE "TOUGH DOG" TIME

CONSUMING AM -FM STEREOS

BEFORE THEY EAT UP ALL YOUR PRCF'ITS.

WITH THE ONLY COMPLETE AM -FM S 'E:REO

ANALYZER ON THE MARKET TODAY... WIh ALL
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COMPLETE AUDIO
AMP SIGNALS

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MONITORED BY DUMMY LOADS AND 2 D'ARSONVAL NETERS

FOR POWER OUTPUT AND TRUE SEPARATION TESTS.

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SEE YOUR SENCORE FLPD DISTRIBUTOR FOR A 10 DAY FREE

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Circle 26 on reader service card

81
www.americanradiohistory.com

new producIs
More information on new products is available from the
manufacturers of items identified by a Reader Service number. Use the Reader Service Card inside the back cover.
RECEIVER, model R36S features 30 watts per
channel into 8 ohms, both channels driven
from 20- 20,000 Hz at less than 0.5% distortion. FM performance includes IHF sensitivity
of 1.9 aV, capture ratio of 2.5 dB and mid band stereo separation of 35 dB minimum.
Operating features include channel selector, ganged bass, treble and volume controls,

anced emitters are tested for all mismatched

conditions. Extra heavy heatsinking is used
to provide extended duty cycle in the course
of everyday use.
Built -in low-pass filter attnuates harmonics in excess of FCC requirements. SWR pro-

Twenty one sweep ranges, 20 MHz bandwidth, 10 mV /div sensitivity, built -in delay line
for use in viewing pulse leading edges, full
dual -trace switching capability, algebraic
waveform as well as ac, low- frequency reject

channel -balance control, switched loudness-

high- frequency reject trigger modes.

Screen size is full 8 X 10 divisions with each
division equal to 1/4 ". Battery recharging circuitry is included within chassis. Operates
from battery, ac or dc powered; battery
charge indicator. 31/2 x 81/2 x 12 in.; 9.5 lbs.;
$1,095.00. Vu -data Corp., 7170 Convoy Court,
San Diego, CA 92111.
Circle 35 on reader service card
and

compensation, mono /stereo mode, tape

monitor facilities, muting and high -frequency
filter switches, speaker connections and
switching for two sets of stereo speakers.
Separate signal- strength and center-channel
tuning meters are included. Rear panel features include choice of 300-ohm antenna
strip or 72 -ohm antenna jack, DIN jacks and
multiple voltage selector for foreign operation, speaker fuses and extra accessory
power outlets. Frequency response: 25- 15,000
Hz. 51/2 x 18 x 13 in.; 24 lbs.; $329.95. -H. H.
Scott, Inc., 111 Powdermill Road, Maynard,
MA 01754.

Circle 3/ on reader service card

OSCILLOSCOPE, model 530A. Medi um -band
width, dual-trace portable scope features internal parallax -free 6 X 10 cm CRT graticule,
1 -mV
sensitivity on both vertical channels
with a full 25 -MHz bandwidth, five display

tection has reset button to reactivate power

amplifier after shutdown. Frequency range:
150 MHz -175 MHz. Power input: PA -2938, 10
watts; PA -2939, 25 watts. Power output:
PA -2938, 80 watts; PA -2939, 80 watts.-Sonar
Radio Corp., 73 Wortman Avenue, Brooklyn,
NY 11207.

Circle 33 on reader service card

POWER SOURCE MONITOR, model VS -200
contains five regulated power supplies. Has
dual -`15 V, 110 mA supply for most common
linear amplifier applications. Has dual polarity, tracking 200 mA power supply that can
be controlled between 50 mV and 20 V. Also
has 0 -200 mV, 10 -mA supply whose polarity
can be reversed.
31/2 digit liquid -crystal meter is 0.5" tall;
monitors the output of any power supply; can

CB ANTENNA, model M -306 is designed for

use on motorcycles, fiber -glass bodied vehicles, boats, snowmobiles and other vehicles

that do not have enough metallic ground

area to assure good operation of a standard
CB antenna. Secret of the unit's performance
is its half -wave -length electrical design with
both base -and -whip-loading coils. Heavy-

i,
1

be switched by front panel control to monitor

modes and stable, high -speed gated trigger

capable of locking any - signal from dc to 40
MHz, including TV line and frame. Special
operating requirement such as dc trigger or
X5 magnification is obtained by pressing the
appropriate button. Also incorporates internal
delay lines and offers optional battery pack.
$1,150.00- Scopes Unlimited, Inc., 1928
South Anaheim Blvd., Anaheim, CA 92805.
Circle 32 on reader service card
AMPLIFIERS, models PA -2938 8, PA-2939.
Both models help to boost low-power mobile
or base station and give it increased talk
power and greater operating range. Operation is automatic and self -protecting. Bal-

the outputs of standard power supplies; can

also be used to measure voltages produced
by other devices; accuracy is 0.2 %. Auto-

matic decimal point placement; automatic

short -circuit shutdown; unit doubles as digital
voltmeter. 5 x 15 x 11 in.; $395.00. -Thinc,
Technical Hardware Inc., P.O. Box 3609,
Fullerton, CA 92634.
Circle 34 on reader service card
OSCILLOSCOPE, model PS940A. Mini -portable scope features computerized triggering.
TTL logic circuit eliminates the need for front
panel adjustment to achieve a stable trace
display. DC trigger mode most often used in
digital test efforts allows user to make vertical position adjustments without losing sync.

82
www.americanradiohistory.com

duty spring above the base loading coil provides shock protection.
Entire antenna is designed for reliable
operation under high vibration conditions.
Has white fiber glass whip and streamlined
chrome spring assembly. Supplied complete
with hardware for a variety of installation
requirements that include mounting on vertical or horizontal surfaces or on round bars
up to 3/4" in diameter. $30.95 -complete with
coax cable and connector. -Antenna Specialists Co., 12435 Euclid Avenue, Cleveland,
OH 44106.
Circle 36 on reader service card
SOLDERING IRON, D I Line. Heater and handle with two-conductor cord set and safety
plug are double insulated; meet latest safety
standard of OSHA and are UL listed. Modu-

lar in concept. Four rugged stainless steel

heaters and three heat ranges provide flexibility for virtually every soldering job. Easy to -use, lightweight and compact design. Han-

WE DON'T CLAIM

need belts?

OUR ELECTRONIC

IGNITION SYSTEM
IS BEST

dle is molded of durable plastic with

finger-ease cool drip. -Ungar, Div. of Eldon

We've thousands in stock

Industries, Inc., 233 East Manville, Compton,

CA 90220.

Circle 37 on reader service card

1 is a two -way system

that is designed as the main speaker in
budget systems or as a second stereo pair.
Frequency response is 35- 17,500 Hz; impedance is 8 ohms. For use with low-power
amplifiers or receivers, yet it can handle as
much as 50 rms watts per channel.
Bass energy is boosted as woofer's back wave energy travels through Venturi -coupled

SPEAKER, Formula

Ready for immediate st-i anent!

Belts for over 1800 mal e and
models of tape recorders, projectors,
dictating machines, video recorders
and our simplified cross
reference system makes it eisy for
you to order. Drive tires, v'heels,
phono idlers also listed. On most
items we can ship the same day.
,

OUR

CUSTOMERS
WRITE

TODAY FOR

FREE

00!

LITERATURE

RESEARCH AND MFG. CO.

CONSHOHOCKEN, PA., U.S.A.

Call or write today for your free

catalog /cross reference char.

PROJECTOR- RECORDER

CORP.

BEIi T

317 Whitewater St., Whitewater,

414/473-2151
Wisconsin 53190

Circle 27 on reader sen-ice card

Circle 28 on reader ercire

The New
Electronics
Book
path that functions as acoustic transformer.
In that path, air motion velocity increases
over broad band of bass frequencies. "Biconex" horn /compression driver assembly
is used to cover mid -range and treble frequencies. 15 X 10v/e X 10 in.; $74.95 each.
BIC Venturi, British Industries Co., Westbury,
NY 11590.
Circle 38 on reader service card

4-CHANNEL RECEIVER, model CS7OR offers

choice of 4- channel systems -discrete or
matrix-or 2- channel stereo; full- featured
digital clock that can be pre -set to turn
complete system on or off; power switch that
is actually a key that can lock the system
in the off position.
Tuner features: FET FM front end, i.f.

Sophisticated Electronics For Fun

By Joe R. Urschel
A totally new step by step guide to the "how to" of
modern electronics, with 190 illustrations in this big
8 1/2" X 11" book.
Now, whether you're a novice or an expert you can benefit from thi' fact filled,
easy to read book. Plus how to use TTL logic, in a non -academic app -oach to
analog and digital electronics.

Special Bonus
two electronic slot rr,: shines .
Complete tried and proved plans to build
electronic clock with chimes juke box with no moving parts compu cl game.
Available in the Chicago area at Kroch's & Brentano's bookstores.

Order Today

r KROCH'S & BRENTANO'S

Please send me
completely satisfied,

29 S. Wabash Ave., Chicago, CL 50603

copies of Sophisticated Electronics For Fun, $6.95 eed If not
may return the book(s) within ten days for credit o' refund.
I

RE

Name
Address
City /State/Zip
idnsed

Charge my K & B account

Payment in amount of S
Expiration date
Illinois residents add 5% tax. Free delivery in Chicago and suburbs. Elsewhere add 40' per boos
handling charge. Sorry. no C.O.D.'s.

amplifier with an IC and three solid -state

filters, IC FM multiplex demodulator, ultra sensitive AM tuner section. Preamplifier sec-

LI Charge my Master Charge or Bank Americard

IIL

-,

ding &

83
www.americanradiohistory.com

RROw
AUTOMATIC

STAPLE GUNS
CUT WIRE & CABLE
INSTALLATION COSTS
without cutting into insulation!

SAFE!

Grooved Guide positions wire for

proper staple envelopment! Grooved Driving
Blade stops staple at right depth of penetration
to prevent cutting into wire or cable insulation!

No. T-18

BELL,
TELEPHONE,
THERMOSTAT,
INTERCOM,
BURGLAR
ALARM
and other low
Uses T -18

round crown
leg length only.

Park, CA 90602.

Circle 39 on reader service card

J'

voltage wiring.

3/8"

SERVICE AID, Omni -Spra, is a nozzle extension that sprays in a 360 circle as well as
out the end -used for cleaning the backs

3/16" in diameter.

in

JRtGS ELECTRON ICS_

SPECIAL
LM1800

THIS MONTH ONLY:

Phase -locked loop stereo demultiplexers. No coils!!
Regularly $2.50; this month only, $2.00 each
008A MICROCOMPUTER KIT
8008 CPU, 1024 x 8 memory; memory is
expandable. Kit includes manual with schematic,
programming instructions and suggestions; all
ICs and parts supplied except cabinet, fuses
and hardware. Includes p.c. boards.
$375.00
MANUAL ONLY, $25.00
008A -K ASCII KEYBOARD INPUT KIT
Kit includes keys, p.c. board, ICs, power supply,
schematic and instructions. This kit is intended
to interface ONLY with the RGS Electronics
008A Microcomputer
$50.00
LAB TYPE POWER SUPPLY
PS 25 -1
Zero to 25 volt
amp lab type
power supply with adjustable current limiting;
has remote sensing and remote programming
for voltage and current. Instructions included.
All parts supplied except chassis and meter(s).
Kit of parts with schematic,
$14.95
P.C. Boards available for PS 25 -1, #007, $3.00
TRANSISTORS
NPN General purpose TO -92
$.08;$5.95/100
PNP General purpose TO -92
$.08;$5.95/100
Other transistors and JFETS available at our
usual low prices; all are tested, good units. Specs
available in our flyer.
RGS ELECTRONICS, 3650 Charles St. Suite K
Santa Clara, CA 95050
(408) 247 -0158
We sell many ICs and components not listed in
this ad, included most of the 7400 series; send
a stamp for our free flyer.
TERMS OF SALE: All orders prepaid; we pay
postage on all U.S. orders. Handling charge of
$1.00 on U.S. orders under $10.00, foreign
orders under $25.00. California residents please
include sales tax. Please include name, address
and zip code on all orders and flyer requests.
DISCOUNTS: 10% OFF ORDERS OVER $25
20% OFF ORDERS OVER $250.
Circle 30 on reader service card
1

-Fits wires up to

Naples with 3/16"

tion has 11 controls that include separate

bass, treble and loudness controls; inputs
for tape, phono and aux.; accommodates
FM wireless microphone; stereo and 4 -channel headphone jacks. Amplifier section has
bridged transformerless circuit, power output in 2- channel mode 22 + 22 watts rms
(each channel driven) into 8 ohms at 1000
Hz; in 4- channel mode 12 X 4 watts rms
(each channel driven) into 8 ohms at 1000
Hz; total harmonic distortion in 2- and 4channel modes is less than 1% at rated
power; power bandwidth in all modes is
30 to 40,000 Hz; frequency response is 40
to 20,000 Hz + 3 dB
3 dB. $370.00.
Yamaha, 6600 Orangethorpe Avenue, Buena

No. T-25 -Fits wires up to

1/4" in diameter.

and sides of components as well as the

fronts. New aid is being packed with all cans
of the company's "Blue Shower." For free
sample, send note to attention of Jean Main.
-Tech Spray, P.O. Box 949, Amarillo, TX
79105.
Circle 40 on reader service card

LEAD BENDER, model N -300 eliminates

measurement and trial and error bending
of component leads. Matching pointers with
eyelet holes in circuit boards by spining
knurled wheel with thumb automatically
spaces bends for insertion of component
into board. Bends are formed by pressing

Same basic construction

and fastens same
wires as No. T -18.

Also used for

RADIANT
HEAT WIRE

SCELBI COMPUTER CONSULTING, INC.

Announces The Totally New and The Very First

Uses T -25 staples

MINI -COMPUTER

1/4" round crown in 9/32 ",

3/8 ", 7/16" and 9/16" leg lengths.,
with

Designed For The

ELECTRONIC /COMPUTER HOBBYIST!

T -18 and T -25

staples also available in Monel and

with beige, brown and ivory finish at extra cost.

No. T-75

ii

-Fits wires and cables

up to

1/2"

in diameter.
RADIANT HEAT
CABLE,
OF CABLE,
WIRE CONDUIT
COPPER TUBING
or any non-metallic
sheathed cable.

leads against sides of pointers with thumb

and forefinger. All axial lead components
are accommodated, e.g., resistors, capaci-

Also used as

DRIVE RINGS
in stringing wires.
Uses T -75 s aples with 1/2"
flat crown in 9/16 ", 5/8" and

!',
t i

7/8"

leg lengths.

Arrow Automatic Staple Guns save 70% in time

and effort on every type of wire or cable fastening ob. Arrow staples are specially designed with
divergent -pointed legs for easier driving and
rosin -coated for greater holding power! All -steel
construction and high -carbon hardened steel
working parts are your assurance of maximum
long -life service and trouble -free performance.
Ask your Electrical Supply Dealer

or write for further details.

Saddle Brook

New Jerscv 07663

"Pioneers and Pacesetters

For Almost A Half Century"
84

a true digital mini -computer with computing power that will astound you! At a LOW,
LOW price you may find hard to believe. This
versatile electronic wonder has been designed
to delight the very heart of every person who
has dreamed of owning their very own computer.
It is all solid state and conservatively designed
to provide years of lasting pleasure. It is a fully
programmable machine.
A complete line of peripheral units are available
to use with the SCELBI -8H. Such as an interface
that turns a low cost oscilloscope into a complete alpha- numeric display system, low cost
keyboard and TTY interfaces, and an interface
that turns a low cost audio tape cassette unit
into a "Mag- Tape" storage system.
Plus
a large selection of software! Programs
such as Editors, Assemblers, Calculator packages, I/O routines for ASCII and Baudot machines and SCELBI interfaces, Data manipulating
routines, Games, and much more.
And, the skill and support of an organization
staffed with professionals dedicated to bringing
you the most computer power for your money.
Professionals who have been delivering SCELBI8H systems for more than a year!
Fully tested card sets for the SCELBI -8H start
as low as $440.00! Complete computers (card set
plus chassis) as low as $580.00. And, for the
real "do it yourself" buffs, we now offer "unpopulated" p.c. card sets starting as low as $135.00.
(Domestic prices.)
Literature available by request:
SCELBI COMPUTER CONSULTING, INC.

This is

tors, diodes, transistors, inductors, etc. up to

V/2
in. diameter x 11/2 in. long with maximum
distance between inside of bends of 1.725
in. $32.50 -complete with spare set of lead
guides.- Harwil Co., 903 Colorado Avenue,
Santa Monica, CA 90401.

Circle 41 on reader service card

TURNTABLE,

model

SR -212.

(331/3, 45 rpm) unit features

Two -speed
heavy belt -

driven 12" aluminum alloy platter. Motor is

a stable 4 -pole synchronous design that
maintains constant speed regardless of line
voltage variations. Cueing device is damped
going up as well as down. No chance for
tone -arm snap-up and loss of correct position when just a pause in play is desired.
All you have to do is move tone -arm over
the record groove and nudge cueing lever.
Arm floats down over the groove and lifts
up again when the side is completed; arm
is an S- shaped design with anti -skate counter

Circle 29 on reader service card

www.americanradiohistory.com

1322 Rear

Boston Post Road

CT. 06460
Phone (203) 874.1573
Circle 61 on reader service card

Milford,

balance in addition to conventional stylus

torce counter balance weight. Comes complete with walnut base. Connection from arm

circuit will maintain batteries at full charge

instrument is connected to ac line.
"HT Converter" A -D conversion technique,
as long as

side the home; intrusion detectors `or doors

or windows; fire detectors; 20 -foot extension
cords; three-way connectors; an easy -tofollow installation manual; identilyilg warning decals. $69.95; expanded del.ix t version
$99.50.- Master Lock Co., 2600 North 32nd
Street, Milwaukee, WI 53210.
Circle 44 on reader service r.: -d
NON -CONDUCTING METAL SHEET for
printed circuitry. To make a sirup e circuit
or a complex multi-layer breact-ard, you
draw or scribe your design diire_U on the
surface of the material which ns'. illy ren-

coupled with LSI, has enabled reduction of

components. Circuit boards, IC's and displays are plug -in. $395.00.- United Systems
Corp., 918 Woodley Road, Dayton, OH 45403.
Circle 43 on reader service card
HOME ALARM SETS, Snap On. Every component is pre -wired with exclusive Snap On

to amplifier is low- capacitance lead that is

suitable for CD -4 applications. $149.95.

Sansui Electronics Corp., 55 -11 Queens
Blvd., Woodside, NY 11377.
Circle 42 on reader service card

DIGITAL MULTIMETER, model 2180. 31/2

digit, bipolar instrument has all five standard
multimeter functions plus five decibel measurement ranges extending from -60 dB to
+56 dB. Basic accuracy of 0.1% and resolution of 100 eV; operates from either ac line
or internal rechargeable batteries.
Functions are pushbutton selected and include ac volts, dc volts, ac current, dc current, resistance and decibels. Its 31 measuring ranges are selected by rotary switch
with additional battery check position that
allows internal battery conditions to be monitored. Automatic integral battery charging

connectors. There are no wires to cut, strip,

solder or splice. Power source is a standard
6- or 12-volt battery.
Each set includes a solid -state control
center that is always alert to fire danger,
even when the burglary system is turned off;
an electronic siren with separate signals for
fire or burglary; a key switch that permits
the system to be turned on or off from out-

ders a working circuit. Pressure :

necessary. For mass producticr
press can be used. Without unir
board, circuits can be erased for ni
designs. Since the metal sheet its
ducting, components and wiring casoldered at random, indeperdh
adjacent areas of the board. For us

-Il that is

letter

new
king new
non-conbe spotnt from

_i

in

solid-

BASIC
POUTER
Now available, our latest version of the amplifier that startit all; the faithful old "Universal Tiger ". We have put
him in a fancy new chassis and added our famous complementary differential input circuit, but this is still the rugged, low distortion, economical amplifier that thousands of
you out there love so well. With a power output of 75 Watt
into an 8.0 Ohm load, or 90 Watt into 4.0 Ohms the
"Tiger B" is the ideal BASIC amplifier for all types of applications; from HiFi systems to public address work, to
instrument amplifiers; you name it. With its tremendous
frequency response, -1.0 dB at 1.0 Hz and 100KHz and
super low distortion of .05% IM at rated output, Tiger "B"
is ideal for almost any application using an audio amplifier.
ed

Nothing but the best components and first quality fibrecircuit boards are used in this kit. The chassis is bronze
anodized and the perforated metal cover is standard.
glass

For those who insist on "guilding the lilly" we have an

accessory kit to add an output meter, input level control,
overheat indicator lamp, front panel power switch, etc.

Circle our reader service number for your free copy of our
latest catalog.

# 275 Amplifier Kit

$64.50 PPd

$ 7.90

(single channel)
AC -275 Accessory Kit

PPd

1--rt

Circle 62 on reader service card

www.americanradiohistory.com

Southwest Technical Products

219 W. Rhapsody, Dept. RE
San Antonio, Texas 78216

orp.

85

AMAZING

RADIO & TV SERVICE DATA

3t-

Your best, complete source for

all needed TV and RADIO diagrams and helpful servicing data.
Most amazing values. Most giant
volumes only $4, some at $2. Cover
all important makes, modela of all
periods. Use this entire ad as your
no -risk order form.
NO

7L9t

OFFER

1969

Circle 45 on reader service card

FIL:411

RISK ORDER COUPON

MONEY-SAVING

Supreme TV manuals are best for faster, easier

TV repairs. Accurate factory data at bargain prices.
Complete circuits, needed alignment facts, printed
circuit views, waveforms, voltages, productimr

TRIGGER'S

GREAT SELECTIONS

Send for this reliable buying

guide to carefully selected:
Amateur Gear Stereo HiFi
Electronic Kits
CB
Radio
Tape Recording
Electronic Parts Antennas
Tubes
Transistors
Tools Books
Test Gear
Count on TRIGGER for the
best in electronics. Write for
this Free Catalog today!

195

RADIO DIAGRAM MANUALS

These low- priced radio manuals simplify all repairs. Cover everything you may need from recent
radios to oldtimers; all types of radios, stereo, combinations, transistor portables, FMAM auto sets. Large schematics,
all needed alignment facts, printed
boards, voltage data, dial stringing,
hints. Volumes are big, 8% x11 .
about 190 pages, each
1965,
1966,
1967-1969 Combined Volume
1960,
1961,
1962,
1964,
1963,
1954,
1955,
1958,
1956,
1959,
1948,
1950,
1951,
1953,
1952,
1940,EACH,$4
1941,
1942,
1946,
1926 -1938 Antique Radios, 240 pages, $7
Television Course, $3
1965 Auto Radios, $2

A MONEY -SAVER
na,

GGER Electronics, Dept. 13 -NO

7361 North Ave., River Forest, Ill. 60305
Send FREE TRIGGER Catalog

FREE

Catalog

TR

Name
EASE PRINT

anteed.

Address

Name'

City:

SEND FOR IT TODAY!

Neer

SUPREME PUBLICATIONS

Address'

IL

City

State

Zip

Zip

Circle 63 un reader service card

whole family, than by assembling your own

Schober Electronic Organ.
You need no knowledge of electronics, woodwork or music. Schober's complete kits and
crystal -clear instructions show you whoever
you are, whatever your skill (or lack of it)
how to turn the hundreds of quality parts into
one of the world's most beautiful, most musical
organs, worth up to twice the cost of the kit.

.I. WHINE ANN TOOL roarraa

do'zsis'isi:iumcc,x.

steps. Same strip block used for all lengths.

All solid -state control; no air required. Preset number stops operation automatically
after selected number of cycles. Non -nicking
blades are made of heat treated tool steel.
Complete panel functions; three operating
speeds -slow, medium, fast. For AWG24 -30.
18 X 20 X 20 in.; 90 lbs.-OK Machine and
Tool Corp., 3455 Conner Street, Bronx, NY
10475.

Circle 46 on reader service card

EXACT REPLACEMENT ZENITH SOCKETS,
Kit No. 39 contains a general purpose assortment of four sockets, none of which has
a substitute. In addition to this kit, Oneida

Now...the most enjoyable

do- it- yourself project
of your life -a Schober
Electronic Organ!
You'll never reap greater reward, more fun and
proud accomplishment, more benefit for the

WIRE STRIPPER, model EWS -10K. Cuts and

strips 5000 wires per hour with 6 in. wire
length. Strip length from 0 -1.5 inches in 0.1
inch steps; wire length from 2.5 -99.9 inches
in 0.1 inch steps. Wire feeds via two stepping motors; wire length and strip length
controlled by gating proper number of motor

FOR THE MAN IN ELECTRONICS

1969 B -W TV, $4
1969 COLOR TV, $4
1968 TV, $4
1967 TV, $4
1966 TV, 4
Additional 1965 TV, $4
Early 1965 TV, 4
1962 TV, 3
1963 TV, $4
El 1964 TV, $4
Early 1959 TV, $4
1960 TV Manual, $3
Additional 1957 TV, $2
1958 TV Manual, $3
TV,$3
$2
TV,
$3
TV,
Master Index to all TV & Radio Manuals, 500

1760 Balsam Road, Highland Park, ILL. 60035

Rush today TV and Radio manuals checked in norisk order form of this ad. I am enclosing full price
plus $1 for postage and handling. Satisfaction guar-

TiR/CGERfircrsowc3

CATALOG

changes, and double -page schematics. Mostly $4

each, some less, for a large annual manual. Check
volumes wanted.
1970 B-W TV, $7
1970 COLOR TV Manual, $4

1954

state printed circuitry, breadboarding, terminal blocks, chassis, etc. -Metal Circuit
Systems Corp., P.O. Drawer 2226, Houston,
TX 77001.

TELEVISION SERVICE MANUALS

1955

WM WNW

tortMlanMElsaYaroa

F've superb models with kit prices from $575

to around $2,300, each an authentic musical
ins rument actually superior to most you see In
stores, easy for any musically minded adult to
lea n to play, yet completely satisfying for the
accomplished professional. And there are accessores you can add any time after your organ is
finished lifelike big auditorium reverberation,
automatic rhythm, presets, chimes, and more.
Join the thousands of Schober Organ builder owners who live in every state of the Union.
Often starting without technical or music skills,
they have the time of their lives
first assembling, then learning to play the modern King of
Instruments through our superlative instructions
and playing courses.
Get the full story FREE by mailing the coupon
TODAY for the big Schober color catalog, with
all the fascinating details!

The sYelloet Organ Corp., Dept. RE -132

43 West 61st Street, New York, N. Y. 10023
Please send me Schober Organ Catalog.
Enclosed please find $1.00 for 12 -inch L.P.
record of Schober Organ music.

NAME
ADDRESS
CITY

STATE

ZIP

Circle 64 on reader service card

www.americanradiohistory.com

also offers zenith sockets S -74-C, an exact

9 -pin replacement and S-75 -C, an exact 12pin replacement. Combination of the kit assortment plus the other two sockets provides
complete Zenith coverage.- Oneida, Box
558, Meadville, PA 16335.
R -E
Circle 47 on reader service card

American Airlines installs TV

on all its luxury planes
Special television systems that provide recorded TV shows or full -length
movies have been installed on all of
American's DC -10 Luxury Liners. Each
DC -10 is equipped with a color videocassette player/recorder in the first
class section and a 25 -inch RCA XL -100
R -E
television set in the cabin.

new lit

components of Mini -State antenna and cabinet design of rotators; also lists components
of antenna mounting kits that are available.
RCA Parts and Accessories, P.O. Box 100,
Deptford, NJ 08096.
Circle 52 on reader service card

HI -FI LOUDSPEAKER SYSTEMS CATALOG.

24 -page illustrated brochure describes floor

standing loudspeaker systems, compact loudspeaker systems, Stonehenge and Ill loudspeaker systems as well as components and
utility systems. Price list is inserted in brochure. -Altec Sound Products Division, 1515
South Manchester, Anaheim, CA 92803.
Circle 53 on reader service card

placements, widely used tuner par-;, chemicals and tools. Indexes for blcw -ups and
uhf tuners. Covers Standard Kollfrran, Oak,
Sarkes Tarzian, RCA, Zenith, Phi c :. Motorola, G.I., miscellaneous, domest c and foreign made tuners. Includes antenra natching
coils and antenna coil replacenior - guide.
$2.00; refundable on first order for roods or
services. -PTS Electronics, Inc_ P.O. Box
272, 5322 Hwy. 37 S., Bloomington. IN 47401.

All booklets, catalogs, charts,

data sheets and other literature listed here with a Reader

Service number are free. Use
the Reader Service Card inside
the back cover.

1974 -75 VHF- UHF-FM TUNER REPLACEMENT GUIDE AND PARTS CATALOG NO. 4.
95 -page catalog contains exact tuner re-

CATALOG. 12 -page brochure explains the company's J -Jacks system for

educational and medical TV systems; permits distribution of uhf, vhf, FM, closed -circuit video and audio signals simultaneously
throughout the school or hospital; also has
2-way signal carrying capability. Covers design and installation, from basic distribution
systems to sophisticated automatic 2 -way
systems. Architect specifications are also included.- Jerrold Electronics Corp., 401 Walnut Street, Philadelphia, PA 19105.
Circle 49 on reader service card

DISC CAPACITORS_

M5M 4L7.

Circle 50 on reader service card

BUSINESS FORMS CATALOG. 32-page catalog for television and appliance firms contains multipart service order forms, repair
tags, sales forms and billing forms. These
forms are in duplicate and triplicate sets,
consecutively numbered and imprinted with
your firm's name and address. Also featured
are business cards, pressure sensitive labels,
carbonless register forms, bookkeeping systems and many other business forms. Illustrations in color. -New England Business
Service, Inc., P.O. Box 500, Townsend, MA
01469.

Circle

51 on

reader service card

CHART, Increase Your Viewing Pleasure.

Complete buyers' and sellers' guide to RCA
Permacolor outdoor antennas, uhf -vhf /FM,
vhf /FM, uhf -only, FM -only; rotators (including Selecta- channel 10W606); three different
types of antenna mounting kits and Mini State antenna system with hand -held rotator
remote control unit. 11 x 44 in.; shows inside

110

20

assorted tubes for $1.00

Untested (some will be

good, some bad).
TAKE A CHANCE FOR
$1.00

12

BARGAIN

for $1"

Assorted capacitances f or 0001 to .1.

Different voltages, roesti 600 volts
K140
N.P.O. N750.
,

BONANZA

1110=10
MINIATURE TRAFSE TOR

ELECTROLYTE:

13 for $170

EDLIE

SLIDE
SWITCHES

Some axial leads, some vs tical mount,

mixed capacitances an,l rtced capacitances and mixed volta;e:
K159

HIGHEST QUALITY

for $100

MINIATURE;

All types, SPOT, DPDT, etc. K106

$100

Includes resistors, condensers. transistors, transformers and various &

sundry parts used to repair transitor
radios, walkie- talkies. tape recorders.
etc.
K107

31

%, 1? watts &

--

60
for

watts. From low to

$100

K113

$1
Used in transistor Ile miniature
K141
applications.

ONLY NEW

Acquired troe

PRODUCTS
EXCELLENT MIXTURE

s-

40,!bav..,

RADIO & TV

Power, Audio, RF
100 for $1.98

Rrcr oing

Any 3 for 31

If

1L4, 155,

LED's in working
condition 3 green or 3 yellow
K101
3 for $1.00
10 LED's asst. in working

conditions $1.00
7 segment
readouts

S.

Defense depots o "moved from soil F

ment (new and uwd).
These are lobos err
tested and ism
teed for one fuel per.
Most are of anti
standard makrrs es
RCA, GE. etc.

Silicon Planar
Untested, NPN & PNP

high ohmages.

12 for

K188 GIANT PACK OF

ASSORTED TRANSISTORS

PRECISION
RESISTORS
All

POTS

KITS

TRANSISTOR
REPAIR KIT

J -JACKS

KIT CATALOG. 56-page catalog lists over 175

different kits ranging in price from a few
dollars to a few hundred dollars. Product
areas covered are amplifiers and preamplifiers, test instruments, power supplies, radio
control apparatus, auto accessories, ham and
CB accessories, musical instrument accessories, FM transmitters and receivers. Many
illustrations. -Audiex Electronics, P.O. Box
156, Station "S ", Toronto, Ontario, Canada

cleaner, speaker systems, -ecording

tapes, hi -fi shelving unit, tape reco ied control center, headphones, audio g3c;ets and
many illustrations. -Etto Electrrr'cs, Box
R -E
741, Montreal, Quebec, Canada.

trol

K159

TUBE
BONANZA!

ELECTRONIC COMPONENTS CATALOG. 35page catalog contains 350 items carrying the
Ultratec label. Among them are mike, tape
and phono accessories, miscellaneous electronic accessories, audio cables and adapters, hi -fi and hobby electronics, tools and
service aids, panel lamps, fuses and battery
holders, wires and cables and electronic
construction components. An alpha /numerical index appears at the end of the catalog.
-Workman Electronic Products, Inc., Box
3828, Sarasota, FL 33578.
Circle 48 on reader service card

STEREO & 4- CHANNEL CATALOG 32 -page

catalog contains 8 -track stereo _cording
decks, AM /FM stereo systems, tLrntables,
mini changers, TV tuner and elects: nic con-

3CB6, 3DG4, 3EH7, 3-i7,

3K76, 354, 304, 413='

K102
$1.25 each
K103

DUAL

POTENTIOMETERS

4BN6, 4BU8, 5CZ5, 5- i,

5T8, 5U4, 6AC7, 6I Ba 6AF4,
6AG5, 6AJ8, 6AK5, d= K6,
6AL5, 6AQ5, 6AU6, tr.X4,
6BA6, 68A11,
6818, 6BN4,
6806, 6853, 6BU8, 61 414,
6826, 6CB6, 6CD6, 6e_ F6,
6CG7, 6CG8, 6CM:
6CQ4, 6DA4, 6DE4 I>G6,
6DK6, 6DN7, 6DT6, Cr W4,
6EA7, 6EH5, 6EH8, 61 37,
6FM7, 6FQ7, 6GF7, 6CH8, 6GK6,
6GL7, 6GM6, 6GNt, 'GU7,
6GV5, 6HE5, 6HJ7,
61-158, 6J6, 6JN6, 61WE,
61(7, 61(11, 6KY8,
6LF8, 61Y8, 6SA7, lS117,
6SN7, 6SV7, 6T8, rMr
6V4, 6W4, 6X4, 7G37
8CM7, 80N7, 8E88, 91417,
12AD6, 12AE7, 124117
12AT7, 12AU6, 12V5
12AX4, 12BA6, 12f9:6
128H7, 128Y7, 12C1,
12CN5, 12D57, 1215,
125C7, 12SN7,
18FW6, 1978, 2.Er, :28W3,
35Y4, 36AM3, 5085
,

25

for $1.00

Assorted ohmages. Originally for

Hi -Fi, Stereo and TV.
K123
asti

o iait>B

TIE LUGS

VOLUME CONTROLS
20 for $1.00
Wire wounds & carbons, up to
meg, some with switches.
K126

50 for $1.00
From 2 lugs up
K143

MISCELLANEOUS
MINIATURE

TUNING
METERS.
2

for $1.00

,\

25 ASSORTED POLY -STYRENE

Top grade capacitors $1.00.
Used by Hi -Fi manufacturers
in most sets.
K285

WRITE FOR

K190

FREE VALUE PACKED

CATALOG

MONEY BACK GUARANTEE

Terms: Minimum order $4.00. Include postage. Either full payment

with order or 20% deposit, balance C.O.D.
FREE CATALOG
EDLIE ELECTRONICS,

25 ASSOR tEl
POLYSTYR :NI
TOP GRAIIE

BONUS
FREE CAPACITOR KIT

With Every $5 Purchase

INC. 2700 -K HEMPSTEAD TPKE.,

marul rcturers

in

K175

LEVITTOWN. N.Y. 11756

Circle 65 on reader service card

www.americanradiohistory.com

CAPACITOR!..

Used by Hi -Fi

most sets

87

le/efl/at/c

COSMOS PROJECTS
(continued from page 60)

MJ-195

MASTER TEST RIG

voltage swing of CI is clamped to the

limits of the power supply voltage by the
input protection diodes of the cos /Mos
gates, the operating frequency is influenced by variations in the supply voltage:
Typically, a 40% variation in supply vol+5 TO15V

FOR TUBE AND SOLID STATE SERVICING

RI
680K

TO PINS
12

FIG.

AND 13

30- BUFFERED- OUTPUT

-KHZ astable

less 19" picture tube

30 KV CAPACITY

+5 TO 15V

HIGH VOLTAGE METER

STATIC CONVERGENCE
FRONT PANEL CONNECTIONS

METAL CABINET
SPEAKER BUILT IN

b/ic

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N Y

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R4
10K

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Circle 66 on reader service card

io

RITA

ME

&BS'

quarterly for the craft audio hul,

COMING UP: A mixing preamp, Customized Dyna PAS. a 24" Transmission line
woofer, 3 -way variable inflection tone con
trot, Synthesizer. PUBLISHED FARE: 9octave Equalizer, Dyna PAT -4 update.
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plus 900w. direct coupled tube amplifier.
Plus much, much more.
"Absolutely top quality...the only U.S. publica
tion completely devoted to the really serious audiophile constructor. CRAIG STARK, Columnist

verything you wanted to

know about

CD

Ignition

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D1 AND

ing the Williamson 20/20 Mark It power amplifier. Although I have built many Enos, Scotts and
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and for the first time learned a lot."
1

-E.A. BUNTEN, Toronto.

LOW LEAKAGE GENERAL

+5 TO 15V

Send for FREE Tiger booklet

(20 pages) which answers all
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14

/
R1

Dl.

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CD4001

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1 MEG

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Grand Junction, Colo. 81501
P. O. Box 1727

Circle 67 on reader service card

'D1 AND D2

a-

Swarthmore PA 19081

Circle 68 on reader service card

www.americanradiohistory.com

LOW- LEAKAGE GENERAL-

FIG. 31VARIABLE MARK /SPACE RATIO

VIBRATOR with independently variable on

tage causes a 5% variation in frequency.

Another disadvantage is that the frequency of operation is influenced by the
transition voltage values of the CD4001
gates and in practice, the actual frequency of operation may vary by 10%
over the production spread of the CD4001 when using identical R1 and Cl
values.
(continued on page 90)

=AM

1/4

CD4001

10

y.
OUTPUT

Who else can give you 5 -Step Stairc

Window, Convergence and Wtlil :e
An exciting first with digital IC
circuitry, offering 5 -step staircase,
window, convergence, white purity
adj'm'ts, and scope triggering. Has
complete rainbow spectrum, 10 gated
rainbow patterns, plus 3 gated bar

multivibrator.

Purity Adjustme r 'ts

patterns. With video IF, RF and

composite video outputs. Perfect for
testing and maintaining CATV,
MATV, CCTV, VTR & NTSC receivers.
Compact, lightweight.

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Cl

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ui

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(51611E

',;

-9300

001

Circle 69 on reader service card

PERIOD OF EACH HALF -CYCLE IS
VARIABLE FROM 8pS TO 800S

TO PINS

8,9,12 AND

13

PURPOSE SILICON DIODES

Its one thing to make the most.

And another to make the best.
We do both.
We make 2out of every 3 automatic turntables in the world.That's mare
Ne
than all the other makes put together. So BSR is big, all right.
also make what we sincerely believe is the best automatic turntatle in
the world. The BSR 810QX for sophisticated systems.
Don't take our word for it. Take it right from High Fidelity m azine's technical reviewer: "Taking it all together performance,
athe BSR 810QX moves into ranking place amon fie
tures, styling
best automatics we know of."
The 810QX at fine audio retailers. Ask for a demonstration or .write
for free literature.

at

Cl
.001

600Hz
M/S RATIO
f

1/11 TO 11/1

TO PINS
8,9,12 AND 13

b-ASTABLE

McDONALO

PURPOSE SILICON DIODES

astable multivibrator.
and oft times.

BSS (USA) Lid

Blauvelt. N.Y. 10913

MULTI -

Circle 70 on reader service card

www.americanradiohistory.com

89

FR

COSMOS PROJECTS
(continued on page 89)

CATALOG of over
1500 unusual tools

carefully selected and tested

assortment of unique, hard -to -find

tools, clever gadgets, precision
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shopping for the technician, craftsman,

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supervisor. Many tools and measuring
instruments available nowhere else.
One of the most unusual and complete
tool catalogs anywhere. Get your copy
of the NC FLASHER today.

National Camera

2000 West Union Ave., Dept.

Englewood, Colorado 80110

Gat

(303) 789-1893
Circle 71 on reader service card

FREE

ALARM

SYSTEM

CATALOG
Controls

Detectors

Both of these disadavantages can be

largely overcome by simply wiring a high
value resistor in series with the input
of gate A, as shown in Fig. 29, thus
enabling the voltage swing of Cl to ex-

ceed the supply voltage. Limiting resistor R2 must have a value at least double that of timing resistor Rl.
In practice, the operating frequency of
this circuit is subject to a change of less
than 5% over the production spread of
transfer voltages, and to a frequency
shift of less than 2% with a 40% change
in supply voltage. Another advantage
conferred by the use of R2 in the Fig.
29 circuit is that of excellent thermal
stability: The operating frequency typically varies by only 1% over the temperature range 40 C to +85 C.
Minor disadvantages of both the Fig.
26 and Fig. 29 circuits are that the leading and trailing edges of the output waveforms sometimes contain a certain amount
of sag and `mush', and the operating
frequency is influenced by variations in
the output loading conditions. Both of
these disadvantages can be overcome by
interposing an inverting buffer stage between the output of the astable multivibrator and the input of the external
loading circuit, as shown in Fig. 30.
A final disadvantage of the Fig. 26
circuit, and to a lesser degree of the Fig.
29 circuit, is that the symmetry or mark/
space ratio of the output waveform depends on the transition voltage value of
the individual CD4001 that is used. An
IC with a transition voltage value of 35%
gives a mark /space ratio of approximately 35/65, and an IC with a value
of 60% gives a mark /space ratio of approximately 60/40. A true square wave
(50/50) output is available only if the
IC has a transition voltage value of
exactly 50 %.
The mark /space ratio of the output
waveform of the astable circuit can be
made variable by using steering diodes
to select alternative charge and recharge
resistance paths for the time -constant
network, as shown in Figs. 31 -a and 31 -b.
In the Fig. 31 -a circuit, the capacitor charges via Dl and the low half of
the resistance chain in one half cycle,
and via D2 and the top half of the resistance chain in the other half cycle.
The mark /space ratio can be varied over
the range 1 /11 to 11 /1 via R2, and the
circuit operates at a frequency of roughly

EXPANDS their

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(602) 263 -8831
Circle

72 on

all at affordable prices

demonstration record,
including explanatory manual,
patch charts and scores
now available -$ 1.00 ppd.

catalog

www.americanradiohistory.com

free

PAIA- ELECTRON ICS

BOX R14359, OKLAHOMA CITY, OK 73114

Circle

73 on

reader service card

Electronics Bench Manual

<:.:ts:sr. '

meisn

WHAT'S AN "E BM " ? ??

and Tab tes, h.iy"-dens::y
to a whnPe cot7.ec.tinn
speei.i.c eecm.s mi;

Ovet 1,000 ItLuetta.Lwns

text eguivatent i.i cantGtt

oj o8fc+ bocFs, attanged

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FAG] LI TIES

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ITnu

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Circle

reader service card

to
modular systems

600 Hz.

The Fig. 31 -b circuit has independently

variable ON and OFF times. In one half
cycle, the capacitor charges via Dl -R1
and R3, and in the other half cycle, it
charges via D2 -R2 and R4. The period
of each half cycle is variable over the
approximate range 8s to 800 ps using
the component values shown.
In this part of the series we have
looked at practical ways of using the
CD4001 in monostable and astable multivibrator applications. In the coming part
of the series we shall go on to look at
sixteen ways of using the CD4001 in
lamp flasher, time delay, oscillator, and
R -E
alarm applications.

line of

SYNTHESIZER

TECHNICAL DOCUMENTATION
BOX 310
CENTREVILLE, VA 22020
]03-p0 -2535
74 on reader service

card

COMPUTER TERMINAL
(continued .from pogo 44)

fflinature
soiflering
statons

0P

and advances the page controls 1 step.

In AUTO, the page will automatically
change every time a character is entered into the last position in a page.
The instant after the page change, the
new page's home position is at the
cursor position. The black "P" key can
still be used to change pages in the
AUTO mode.
In the AUTO STOP mode, the operation is identical except that the automatic page change can be stopped on
any page desired by wiring from the
PAGE switch to one of four points. This
gives the operator the advantage of being able to receive data into memory
in the automatic mode and retain it,
say, in the first 3 pages, and work on
the 4th page without writing over it,
and not having to change any switches.
In either automatic mode, pressing
the clear key (black "C ") will have
the same effect as entering data into
memory in the last position. This results in a page change every time you
clear a page in automatic. This gives
the operator the advantage of clearing
all 4 pages with 4 key strokes of the
clear key.
Power supply

The power supply consists of two

paralleled power transformers (for

N0.1 ANSWER
FOR

PRINTED CIRCUITS

aYWeller
MP Series. Two models, 650 F or
750 F output, designed especially for

today's printed circuit electronics.

Famous closed loop control protects
sensitive components from heat damage. Comfortable pencil-grip iron with
non -burnable cord. Power unit operates from line- voltage with step -down
transformer. ON /OFF switch and red

indicator light. "Non- sinking" tool

stand. Tip -cleaning sponge receptacle.
Variety of available tips multiply usefulness of this versatile station.
Ask your local distributor or

write...

Weller - Xcelite
Electronics Division
(

The Cooper Group

BOX 728,
APEX, NORTH CAROLINA 27502
Circle 75 on reader service card

COOPER

MDUSTRIES

P. O.

added current and packaging requirements), a +250 volt unregulated supply, two +5 volt regulated supplies,
a -10 volt an -12 volt Zener regulated supply.
The +250 volt supply runs the self
scan plasma display. One of the +5
volt supplies runs all logic on the main
board, and the other runs the keyboard, modem/ coupler board, and add
on memory board. The -10 volt supply powers only the memory, while the
-12 volt supply is connected to the
UART and to the modem /coupler
board to power the op -amp and XR210
demodulator.

key sends a pulse to the 2 -bit page

counter which increases its count by

niflget

c!

Iriver

seit3

.Xceuce

FOR DOUBLE DUTY ON D)ENS

:00043
OF POPULAR SCREWS ANC HUTS

Three new assortments hay,: j lined

Xcelite's family of "Compact Cot rertiNobles." Each an Xcelite "original
where will you find such a ver .it.y of
sizes and types in a midget set, for
driving slotted, Phillips, Allen, scniiox,
'

hex, and clutch head screws.

nuts.
All of professional quality,
made of finest materials.

ision

hex

AE -

king

"double duty" with torque i rr >lifier

handle that slips over color -: oded
midget tools for longer reach ?reater
driving power. Each easily kit n fable
on the bench or in the service + thru
Xcelite's exclusive, optically clee r astic
"show case" that closes secu a with
positive snap -lock.

NEW!

-3
-4
-3

slot tip, 2 Phillips screwdrivers, 5 nutdrivers

slot tip, 3 Phillips screwPS140
drivers, 3 nutdrivers
PS6
slot tip, 3 Phillips scrrwririvers

Tape recorder memory

Using the tape record feature to
record and play tapes from the CT256, a medium quality (cost greater

PS130

than $50) or better cassette recorder

is advisable along with a good quality
recording tape. Of course a good reel
to reel machine would insure better
data integrity but good results are obtainable from a cassette machine.
Making a recording is as simple as
connecting a miniature phone plug to
the jack on the back of the CT-256
and the other end to the "mic." input
on your tape recorder. Once you have
(continued on page 106)

PLUS -PS88,PS120,PS7,PS&39, PS44,

and PS -TR -1 with varying selec

tions of screwdrivers
and nutdrivers.
Ask your local

130

distributor or wr

..

Weller- Xcelite
Electronics Divi. ;i rn

41

The Cooper Group

COOPER

ORCHARD PARK.

INDUSTRIES

N.i

Circle 76 on reader service

www.americanradiohistory.com

to

c.:

14127

rd

91

There's a new Heathkit

everyone on

The Heathkit Digital Color TV is for

two kinds

of people
... those

who understand
electronics, and
those who don't

People who understand electronics

will appreciate the GR- 2000's advanced digital design, incorporating
on- screen channel readout
and optional clock. Digital
logic circuitry programs
up to 16 stations in any
sequence. Then just
press a button -you'll
never have to switch
through a "dead"
channel again.
And our exclusive
VHF /UHF varactor
tuner eliminates clunking
contacts that corrode and noisy motors that break down.
The GR -2000 also has
the industry's first
fixed -filter IF amplifier. There's no
need for instrument
IF alignment ever, so
the picture stays bright
and clear year after year. And even in
urban areas where stations
are packed closely
together, there's virtually no adjacent
channel interference.
The 100% solid -state
chassis uses 19
integrated circuits
more than any other TV
around. You'll get
superior pertormance and reliability
no conventional set can match.
A built -in dot generator and test meter
make it easy to keep the GR -2000 in
peak condition without expensive
service calls. The slide -out service
drawer and hinged, swing -out chassis

4000

put everything in easy reach. If anything ever goes wrong, an extensive

trouble- shooting guide will help you
fix it.

And people who don't understand

electronics will enjoy the best looking
picture around. Popular Electronics
said the picture on the 25" (diagonal)
screen "can only be described as superb. The Black (Negative) Matrix
CRT, the tuner and IF strip, and the
video amplifier provide a picture equal
to that of many studio monitors..."
Everyone likes the on-screen readout
that puts the channel number into the
picture whenever you want it. When
you change channels or touch the re-

call button, the big, bright digits

reappear. Add the optional clock
module and you'll see the time as well
as the channel.
The optional wireless remote control
makes the GR -2000 even more enjoyable. Change channels, adjust the volume, set tint and color intensity and
turn the set on or off from across the
room. And, a touch of the Volume bar
automatically returns the digital readout to the screen momentarily. It's an
amazing handful of convenience.
Even if you don't have a lot of kit building experience, you'll enjoy the
GR -2000. Illustrated step -by -step in-

www.americanradiohistory.com

structions, prefabricated wiring harnesses, transistor and IC sockets and

modular circuit boards greatly simplify assembly.
See the TV the experts are talking
about. Popular Electronics summed it
all up: "In our view, the color TV of
the future is here -and Heath's GR2000 is

it!"

GR-2000 -the TV everyone can ap-

preciate.
Mail order price for chassis and tube,
$669.95. Remote control, $89.95, mail
order.
Cabinets
start at
$154.95,
mail

order.
(Retail
prices

slightly
higher.)

Christmas gift for

new
your list Our
Heathkit
Give your scientist, engineer or student a gift he'll use all year long.
Finger -sized keys and 8 bright 1/2" digits make it easier to use than pocket
calculators. Cumulative memory and

register exchanges virtually eliminate

scratchpad work. Performs arithmetic
plus trig and arc trig in degrees
or radians, common
and natural
logs,

Desktop
Electronic
Sliderule

Solves Your
Gift- Giving

Problems

New Heathkit Electronic

Clock /Timer for Car,
Boat or Plane

-61.111111141111111
1

r
A timely

gitt-

electronic clock and a 20 -hour rally

timer, both with quartz crystal aDcuracy. Bright 1/2"-tall digits dim automatically at night. 12 VDC, mounts an or
under dash. Kit GC -1093, 2 lbs., mail62.95*
able
an

Two Heathkit Electronic

Clocks with Standby Power

powers of e,
square roots,
inverses, pi
and exponential
functions.
Kit IC -2100, 4 lbs.,
mailable ..119.95*

New Heathkit

Aircraft Strobe

A bright idea for the pilot on your list

Unique New Heathkit
-or for anyone who needs an emergAM /FM Digital Clock Radio
ency marine or marker light. It meets
Our outstanding clock radio makes FAR 23.1401 and

even sleepy Santas happy.

Two beautiful gifts -the GC -lO 2A is

a clock with a snooze alarm; tic GC1092D reads the time in 6 digit:. the
month and date in 4 digits. Bolh have
standby power to keep the cl c k on
time without the display even c :ring
temporary power interruption :. (Batteries not included.) Kit GC- 109;!A or
each 81.95*
D, 5 lbs., mailable
Time /ldarm

assembles easily in
just one evening. For
12 VDC neg. ground.
With clear lens,
optional red
and red /clear
lenses available.
Kit OL -1155, 3 lbs.,
mailable ....54.95*

The electronic clock with snooze

alarm features a gentle "beep" with
adjustable volume. Or wake to the Learning's Fun With Our New

component -quality AM/ FM radio. Heathkit "Electronics Workshop"

included) keep

Standby batteries (not

the clock on time during power inter- The JK -18A teaches kids electronics
ruptions. Kit GR -1075, 1G lbs., mail- the easy learn -by-doing way. 35 excit129.95* ing projects include light meter, sound
able
meter, transistor radios. For safety,
it's battery
powered and
requires no
soldering.
(Batteries not
included) Kit
JK -18A, 10 lbs.,
mailable ..34.95*
Only llNl

on reuderAervrce curd

www.americanradiohistory.com

Heathkit Exhaust Analyzer

Checks Your Car's Tune Up
Make everyone's Christmas whi te and
cleaner -be sure your tune up is yelping clean up the environment. Big 41/2"
mete reads

relative
comhL stion

effirHncy,
;ti' -fuel
ra;ic and
percer tage
carbon mono Kide.

Kit CI -1080, 6 lbs., mailable ...5095*

95

Exciting new Heathkit

Christmas diving
new Heathkit
dual-trace DC-15MHz scope
Compare the features:
Dual -trace with true X -Y

capability
1 mV /cm vertical sensitivity
over the full bandwidth
Post -deflection accelerated CRT
for bright trace, fast writing
Vertical amplifier delay lines for
pulse analysis capability
Digitally controlled triggering
for exceptional stability
Typically triggers up to
45 MHz guaranteed to

30 MHz

It offers a
lot more than
just a low price

The Heathkit 10 -4510 is your best

'scope buy for two good reasons
does more and it costs less.
Time base sweep up to 100 nsec /cm.
There's always a reference baseline,
even when there's no trigger signal.
The time base can be precisely triggered at any point along the positive
or negative slope of the trigger signal.
In automatic mode, it triggers at the
zero crossing point.
Modes of display. Either channel can
be displayed as a function of time or
both can be displayed together. In
X -Y operation, channel 1 provides
horizontal deflection and channel 2

provides vertical deflection. There are

22 calibrated time bases from 0.2 sec/
cm to 0.1 sec /cm. The sweep speed
is continuously variable between
switch positions. Any speed can be
expanded five times by pulling out the
control knob.
For easy calibration, a 1 volt peak -topeak square wave is available on the
front panel. The regulated supply operates from 100 -280 -volt AC power.
Kit 10 -4510, 34 lbs., mailable 549.95*
Assembled SO -4510, factory -wired &
calibrated version of the 10 -4510, 34
750.00*
lbs., mailable

New Low -Cost Heathkit

each step. Attenuator accuracy is 1

dB; frequency accuracy is 3 %. Non linearity of the triangle waveform is
5% max., symmetry is within 10 %.
Sine wave THD is 3% max. from 5100k Hz. Square wave rise and fall
times are 100 nsec max. 105 -130 or
210 -260 VAC. Kit 1G -1271, 7 lbs., mail99.95*
able
Assembled SG -1271, factory -wired &
calibrated version of 1G -1271, 7 lbs.,
140.00*
mailable

-it

Function Generator
A true function generator, not an oscillator, delivers sine, square and triangle waveforms from 0.1 Hz to 1
MHz. Short -proof output supplies 10
volts peak -to -peak into 50 -ohm load.
A calibrated step attenuator adjusts
from 0 -50 dB (10V to 30 mV) in 10 dB
steps. A variable control provides up
to 20 dB of additional attenuation at
96

www.americanradiohistory.com

projects -timed for

Coming in December...

A new

generation of
Heathkit ham
radio equipment
New Heathkit SB -104 transceiver

the SB -104
Years ahead in design & features
is a complete rethinking of what a CW /SSB
transceiver should be. It utilizes the latest digital & solid -state technologies. The "104" is completely solid -state from the front end to the RF
output.
Totally broadbanded. You can switch from 3 to
30 MHz without preselector, load or tune controls.
True digital readout with 6 bright digits to indicate the frequency with accuracy to 100 Hz.
Mobile- ready. The SB -104 operates from 12
VDC, so its ready to go mobile when you are.
Optional features include a plug -in digital noise
blanker and 400 Hz crystal filter for CW.
Just about the only things that aren't totally new
about the "104" are the quality and easy assembly that have made Heath famous. Kit SB -104,
669.95*
31 lbs., mailable
Kit SBA -104 -3, 400 Hz CW crystal filter for SBlb., mailable
34.95
104,
Kit SBA -104 -1, digital noise blanker for
24.95*
lb., mailable
SB -104,
Kit SBA -104 -2, mobile mount, 6 lbs.,
34.95
mailable

New Heathkit SB-230 1 kW

conduction -cooled linear

New Heathkit 5- Function

SB -634 station console

High -power match for the SB -104. Lowest cost

conduction cooled linear on the market. 1200
watts PEP and 1000 watts CW from less than

Five accessories in one

a 24 -hl.1 6-digit
electronic clock, a ten -minute digital J timer
with visual and /or audible alarms, EF wattmeter, SWR bridge, hybrid phone patch 1,4 th manual and VOX controls. Kit SB -634, 14 Its., mail179.95'
able

100 watts input. It's also rated at 400 watts input for slow -scan TV and RTTY. And absolutely
silent
no blowers, no fans.

Full metering of relative power, plate current,

grid current and plate high voltage. Safety features include microswitch interlocks for top and
bottom shells, thermal shutdown, fused cathode,
on /off switch with circuit breaker for power
transformer.
On the air in 15 to 20 hours. Fast, easy assemno
bly, then check it out with an ohmmeter
alignment necessary. Kit SB -230, 40 lbs., mail319.95*
able

New Heathkit SB -644 remote VFO

Designed exclusive for SB -104, it ow'. Jes the
ultimate in multi -mode operation wiith 1vo crystal sockets for fixed frequencies. Nc modifications -just plug the VFO into the "104 and go
VFO frequency even reads out or tie 104's
digital display. Kit SB -644, 10 lbs.,
119.95*
mailable

New Heathkit Fixed station

AC power supply

New Heathkit SB -614

station monitor scope

How clean is your signal? The bright 11/2 x 2"
screen helps you keep your rig in peak condition. Reveals a wide variety of operating probnonlinearity, insufficient or excessive
lems
drive, carrier or sideband suppression problems,
regeneration and key clicks. Monitors AM, SSB
and CW signals up to 1 kW from 80 to 6 meters.
139.95'
Kit SB -614, 17 lbs., mailable

Powers the SB -104 from 120 or 240 ti

phisticated regulation assures almost n.
in voltage from no load to full load. Er
ply fits inside SB -604 speaker cab net
1144, 28 lbs., mailable

AC. So-

change
re supKit HP-

89.95'

New Heathkit SB -604

station speaker
Response -tailor., Ito SSB
and designed o match
the SB -104. Large enough to
house HP -1144 AC pow r supply.
Kit SB -604, 8 lbs., mailable ....29.95'

NONOVIIMINISMIMIMMAIMS

1111111111111111111

Heath Company, Dept. 20 -11

Benton Harbor, Michigan 49022
Send for your FREE 1975 catalog today.

Please send my free 1975 Heathkit Catalog.

Please send the merchandise checked below. I've
plus shipping, in payment.
enclosed $
,

HEATHKIT ELECTRONIC CENTERS

Units of Schlumberger Products Corporation
Retail prices slightly higher.
ARIZ.: Phoenix; CALIF.: Anaheim, El Cerrito, Los
Angeles, Pomona, Redwood City, San Diego (La
Mesa), Woodland Hills; COLO.: Denver; CONN.:
Hartford (Avon); FLA.: Miami (Hialeah), Tampa;
GA.: Atlanta; ILL.: Chicago, Downers Grove; IND.:
Indianapolis; KANSAS: Kansas City (Mission); KY.:
Louisville; LA.: New Orleans (Kenner); MD.: Baltimore, Rockville; MASS.: Boston (Wellesley);
MICH.: Detroit; MINN.: Minneapolis (Hopkins);
MO.: St. Louis (Bridgeton); NEB.: Omaha; N.J.:
Fair Lawn; N.Y.: Buffalo (Amherst), New York City,
Jericho, L.I., Rochester, White Plains: OHIO: Cincinnati (Woodlawn), Cleveland, Columbus; PA.:
Philadelphia, Pittsburgh; R.I.: Providence (Warwick); TEXAS: Dallas, Houston; WASH.: Seattle;
WIS.: Milwaukee.

GR -2000 Color TV

JK -18A Junior electronics

SG -1271 Function

GRA- 2000 -1 Digital

workshop

clock module

GC-1092A Digital clock

GRA- 2000-6 TV remote

with snooze alarm

control

GC-1092D Digital clock

generator (assemt led)

SB -104 Transceiver
SB -104 -1 Noise bracer
SB -104 -2 Mobile mo int

IC -2100 Calculator

with date display

CI -1080 Exhaust analyzer

10 -4510

GR -1075 Digital

clock radio
GC-1093 Digital car
clock /timer

SB-104 -3 CW crystal filter

SB -230 kW linea SB -614 Monitor score
SB -634 Station mcni or
SB -644 Remote VFO
HP -1144 AC power s ipply
LI SB -604 Station spea .er
1

Oscilloscope (kit)
SO -4510 Oscilloscope
(assembled)
1G -1271 Function
generator (kit)

Name

Address
City

State

Zip

'Mail order prices, FOB factory

Prices and specifications subject to change without notice.

-541
J

('u'rlr

Ilk) ,m rreeJrr .cl-11(r reerJ

www.americanradiohistory.com

97

NEW FREE
CATALOG OF

CIRCUIT DESIGN
& BREADBOARDING
EQUIPMENT!
NOW

riexL month

... TEST NEW

DECEMBER 1974

CIRCUIT IDEAS, I.C.'S,

DISCRETE COMPONENTS WITH NO SOLDERING!

Circuit Design's new catalog has everything you need to take you from circuit
concept to working hardware in minutes.
Featured items include the great SK -10
socket for solderless circuit design and
testing, the NEW SK -20 socket (only
$2.75) for smaller circuits, the versatile
Digi Designer (in kit form or assembled),

New 1975 color TV circuits

The new sets have arrived and with them
come some fascinating circuits. We've
selected several of the more interesting
ones and describe them here.

new Op -Amp Designer, plus power

supplies, pulse generators, digital logic
courses, plug -in socket boards, and
much more.
a

Write today for your free copy.

Digital Remote Control For TV

CIRCUIT DESIGNS, INC.

Punch out the channel on a calculator type keyboard. The set switches and the
channel number appears on the screen.
See how it works.

P.O. Box 24, Shelton, Conn. 06484

Exclusive mail order dist. for E &L Instruments.
Circle 77 on reader service card
Kleps 40
Kleps

Kleps 30

20

Kleps 10

Kleps 10

Kleps 20

Pruf 10

Clever Kleps
Test probes designed by your needs -Push to seize, push
to release (all Kleps spring loaded).
Kleps 10. Boathook clamp grips wires, lugs, terminals.
$1.39
Accepts banana plug or bare wire lead. 43/4" long.
$1.49
Kleps 20. Same, but 7" long.
Kleps 30. Completely flexible. Forked -tongue gripper. Ac;1.79
cepts banana plug or bare lead. 6" long.
Kleps 40. Completely flexible. 3- segment automatic collet
pins.
connector
wire
PC
terminals,
ends,
-board
firmly grips
;2.59
Accepts banana plug or plain wire. 61/4" long.
Kleps 1. Economy Kleps for light line work (not lab quality).
$ .99
Meshing claws. 41/2" long.
Pruf 10. Versatile test prod. Solder connection. Molded
pin
fits
banana
"Bunch"
tool.
as
scribing
phenolic. Doubles
$ .89
lack. Phone tip. 51/2" long.
All in red or black - specify. (Add 50C postage and handling).
Write for complete catalog of - test probes, plugs. sockets,
connectors, earphones, headsets, miniature components.

Kleps 40

PIE.

PLUS
Step -By -Step Troubleshooting Charts

Equipment Reports
Appliance Clinic
Jack Darr's Service Clinic

INC.
RYE INDUSTRIES
N.Y. 10543
1228

All About MOS Shift Registers

Learn how these special IC's work and
how you can use them effectively.

Kleps

Available through your local

distributor, or write to:

INOUE.

Build DVM Plug -In For Grinchwall

Add -on plug -in multimeter makes your
Grinchwall digital instrument more useful
than ever.

Spencer Place. Mamaroneck,

In Canada: Rye Industries (Canada)

Circle 78 on reader service card

Ltd.

December issue goes on sale November 18, 1974

www.americanradiohistory.com

SHOPPING POWER FOR YOUR DOLLAR

FREE GIFT WITH EVERY ORDER
CANADIANS: Ordering is easy -we do the paperwork

FREE $1 BUY WITH EVERY 10 YOU ORDER

Only applies to "$1 ' Buys

RCA

110 FLYBACK TRANSFORMER

the Mar-

We scooped

Leaves messages for other for replay

width Incl. Schematic

application
Diagram

for any

...

TV.

495
110 TV DEFLECTION YOKE
for all types TV's incl schematic

250 -ASST SOLDERING LUGS

Test Equip. Special Discount Prices

best types and size

E/CO

90

#50-Ae,t
100 -ASST 6/32 SCREWS

SHARP

to

Color CRT's
70 COLORE

YOKE

1095

For all round color CRT's

V.O.M.
MODEL
THL -33 2% Aocuracy -1%
SPECO

Precision Resistors-Meter Fuse

Protection Full Range- Complete 995
with teat leads & Manual
PAIRS
MATCHED
TRANSISTORS NPN & PNP
(2N4252 2N2904)(2N2222- 2N2907) 10
Each set
TV TUNER
Model 175 -1164 & 175 -1151

(Parallel)

SARKES TARZIAN TUNER

41mc
Latest Compact
Model good for
all 41 me TV's.
BRAND NEW

-to

WESTINGHOUSE FM TUNER
# 476- V-015D0 1 Transistor -.
WESTINGHOUSE FM TUNER
(12DT8 Tube)
UHF TUNER Transistor Type
Used In all TV sets

-_ 399
10

395

TUNER-

STANDARD
Transistor (Guided Grid)

Channel closed circuit _PHILCO TV TUNERS

1-1Model -76- 13983 -3 (50J7 -3HQ5)
GARDNER TUNER Part
1-1 #7A 120 -1 (4GS7-2HA7 Tubes) _
G.E. -TV TUNER (2GK5 -4LJ8)
Model #EP 86x11
4

Condensers

100/75 mfd-300V, 70 mfd -25V

1
495
795

795
10

Condensers

300 mfd -200V, 200V,

-_
300/60 mfd -150V .
995
PHILCO UHF /VHF TUNER
-- - -- 7
Transistorized
195
1-1 GE TV TUNER
-_
ET 86x196, (6GK5 -8BL8) __

--

J 00

1
TV Antenna Back of 999
UNIVERSAL
5 section rods
set mounting

Approved 6'

...
LATERAL

79
Magnet Assy.
color TV's _ 1
COLOR CONVERGENCE Assy.
249
Universal type-good for most sets
COLOR-TV RECTIFIER-Used 195
n most color
olorsets
sets-6500
-65 kv 3 for_
2 COLOR -TV CRT SOCKETS
100
Wired leads, for all color TV's _._
3-RCA I10 CRT SOCKETS
10

BLUE
Replacement for most

- 6FQ7 - 6GH8 - 6JW8

8FQ7 - 12AT7 - 12BD6 - 12FX5

5 For

3CB6

350
j00

2CY5 - 30T6 - 4DT6 - 5U8 -6AF9

600
6CB6 - 6DW4 -17BE3 - 17Z3
5 For
35EH5. 50EH5
6CL8

6U8

6U8

5 For
25CD6 - 25E5
WHILE SUPPLIES LAST

5 For

- 10128 - 12DQ6

700

1000

RADIO
broken,

TRANSISTOR
asst type good, bad.

150

as -is, potluck

400

broken. as -is, potluck _

200 ASST. 1a W RESISTORS
Top Brands, Short Leads,
Excellent Selection __..

10

'/ WATT RESISTORS 10

stand, choice ohmages, some in 5% 1
75 -ASST

1--1

100-ASST

WATT RESISTORS
1---1 stand. choice ohmages, some in 5%
70-ASST I WATT RESISTORS
stand, choice ohmages, some in 5%
35 -ASST 2 WATT RESISTORS
stand, choice ohmages. some in 5%
PRECISION RESISTORS
asst. list -price $50 less 98% _.
20- ASSORTED WIREWOUND
1_1 RESISTORS, 5, 10, 20 watt
10-ASST
SWITCHES
1/2

SPST. SPDT,IDPDT, etc

HEAT SINKS
For Transistors

20- ASSORTED

II-

TV COILS

LF. VIDEO, sound radio, etc.

10

i1O0
i10

i0

1
100

i100
110

ELECTROLYTIC COND.

200/300/10/100 MFD -25V

ELECTROLYTIC COND

5-9

TV

ni 4-

_-

10

100
450

10
1N34,

1
1
1
100

0
1
100

95
ELEMENT Color Outdoor
ANTENNA Big shot Jr. List $11.95
4-Polarized CHEATER CORD 10
Grey
COLOR TUBE
95
BRIGHTNER
495
90 COLOR TUBE

70

BRIGHTNER_

2- Colorburst

_-

and 100 -8/32 HEX NUTS

100 -ASST 2/56 SCREWS
LI and 100-2/58 HEX NUTS
1110 -ASST 4/40 SCREWS
and 100-4/40 HEX NUTS
100 -ASST 5/40 SCREWS
and 100-5/40 HEX NUTS
500 -ASSORTED RIVETS
most useful selected sizes
300 ASSORTED WASHERS
most useful selected sizes
R
BUMPERS
L-1 for cabinet bottoms-other
100
t RUBBER GROMMETS
L-1 best sizes

-Ali

3-ELECTROLYTIC COND

order

10
1

TV
most useful assortment

1 00

100
1

TOOLS 100
1

#1

ALIGNMENT TOOLS 149

IGNMENT
For Color
T
ALIGNMENT 279

TOOLS

Most poplar

-TRACK TAPE Playback Deck 9750

Compact design fits anywhere

CONDENSERS 100
1

ELECTROLYTIC
200/200 mfd. -200V
2- ELECTROLYTIC COND
1500 mfd. -35V
1-5' SPEAKER
1-1 with output transformer
12' UNIVERSAL SPEAKER

...
...
get

100

1 39

89

5
Top Quality
Large Magnet
PHILCO SPEAKER
Large Magnet ._ 299
Top Quality

IM

299
Special BuyR
129
4' UNIVERSAL TWEETER
1
Li 1 oz. Magnet
5 -10K-2 WATT BIAS POTS 10
Used In solid state application __
69e
2./2"x4" SPEAKER
EA. 7
Special Buy 10 for $5
4'x6" "QUAM" 16 OHM SPK.
Special BUY
179
Large magnet
(10 for $15.00)
RONETTE Store.) Cartridge
latest dual sapphire flipover type
Stereo Headphones Bt -Fi Quality C95
Complete with Stereo plug
TRANSISTORS 00
1--1
NPN & PNP 2N404, 2N414, etc.
UTAH 8'-HEAVY DUTY IO OZ. 450
SPEAKER Ceramic Type -8 Ohm
N

-i

Large

...

...

VARCO Stereo Cartridge -CN -72

With mounting bracket, flipover 295
needle

ELECTROLYTIC
300 mfd.-200V
15- DIPPED

10
--CONDENSER
-- --10
-

MYLAR CAP.

.01 -600V

15- DIPPED MYLAR

.033-600V

CAP.

10

MYLER Condensers

21"

Sq. Panel
TACHOMETER
Meter 1 -VDC, full scale 33 Ohm

10
200

coil resistance 0 -6000 R.P.M.

CASSETTE type dynamic Mike 999
with universal plugs -200 Ohms
-SETS PHONO PLUGS &
"1 0
PIN JACKS RCA type
8-MINI PILOT BULBS With
8" Leads-6.3V 30MA (5000 Hrs) 1
8-MINI PILOT BULBS With 12" 1 0
Leads -6.3V, 150MA (5000 Hrs.)

I-

10

..

TAPE REEL

5"
7"

.09
.12
.29
.35

TAPE REEL
TAPE REEL..

Color Demodulatr Chip

EQv. TVC M-I.

CO-AX CABLE

(Sprague

100'-$4.50,

ro

Scott-Fisher te

15- ASSORTED

395

limit)

50

969

uit

1L0

IC'S

For Experimenters
NPN HV TRANSI ;TOR
Silicon
RCA -SK- 3021 -14ep -210

RCA-SK-3026-Hep-2,1

769
1

8K3006, 8K3018, SK30:O

K3122, K3124

125

Transistor Specials -Yser Choice

Specials -Ytur Choies

198
1
K3024, 8K3010
/Indoor MINI $PIIAKER
Outdoor
4 " -1 Oz. Magnet
O3 me
G50
Audio level control
CONVERGENCE REC IFIERFor COLOR TV 4 Cell- 100
Used in RCA- Phllco Seer 1tb, etc. 1
TV DAMPER DIODE
Replace RCA part #12031: __-.$2.29
_.$4.95
Dual
RCA part #1399".r

-8

ni

Cassette

Stow

Deck

TOSHIBA
Model KT -403DC Recoed
Play Back

TELMATIC

7995

Tuner -Matt I T -730

Portable "Substi- Tuner" -.

Instant Tuner Check
TELEMATIC Test Jig M.
1_1 E1 -190-Master RigsCombo Rigs -Eto
R1gr

3 SPEAKER -7

WAY

"1E

9050

JO

4(195

.ECTOR 169

SWITCH Wall Mount

STEREO MICRO PHO(IEt
FL 1979/01 M ade
Ila.d SET
25' Shielded MIKE Ca16 .E
Grey 25/1
ASSORTED FUSES
Popular asstd. ampere r
acts
50 -RADIO & TV SOC KITS
all type 7 pin, 8 pin, 9 rlr etc. _
1 -5'x7" UNIVERSAL 8 K.
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BROOKS RADIO & TV CORP., 487 Columbus Ave., New York, N.Y. 10024
Circle 79 on reader service card

www.americanradiohistory.com

TELEPHONE

MINI-BAR
generator
color

BG-10

battery- operated, fits in shirt pocket!

...

automatic on & off with LED indicaall

fast, easy hook -up with coaxial cable
Low power consumption for exessential patterns ...
tended battery life (Uses inexpensive 9 volt batEnclosed RF
teries)
Shuts off when not in use
Size: 5 1/2" x 3" x 1 1/8 ". Only
cable compartment
CMOS LSI
12 ounces
TV station type sync signals
IC for all counting functions
no internal adjustments
RF output on Ch. 4 or 5.
No AC plug in

tor

....

BUILD

, ic

with

3-way
function
generator
Build this precision instrument for less than
$11. Add your own case and power supply
and you've got a quality compact generator
By ROBERT COLMAN

$89.50

BG -10 (less battery)

CC-1 Carrying Pouch
See

$ 2.95

your distributor or write

LECTROTECH,
INC.
J
L

11,

5810 N. Western Ave.,

Chicago, Illinois 60659
(312) 769-6262

Available in Canada
from
.111Superior Electronics
Inc

Circle 80 on reader service card

the smallest
digital multimeter

> IM -4
197
.02%

Full four digits.

1.9"

H X

2.7"

W X

4.0"

15 ranges & 3 functions

READERS OWN
A LARGE NUMBER OF Radio- Electronics
elaborate and costly high -quality, high -fidelity sound systems.
To check the performance of sound systems of this type
requires the use of sophisticated high -performance signal
generators. Unfortunately, such instruments are usually
very costly and would not be used often enough to justify
their purchase.
But there is an alternative. It is a 14-pin monolithic integrated circuit which can deliver sine, square, triangle and
pulse waveforms that are highly accurate. This new IC is
the Intersil 8038. It operates over a frequency range from
.001 Hz to
MHz and is highly stable over a wide range
of temperature and supply voltages. By using additional
external voltages, it is even possible to use the IC as a sweep
generator and add FM modulation. The device uses the
latest technology, including thin-film resistors and Schottkybarrier layer diodes.
Although the more complex functions of the 8038 are
certain to interest some readers, we were primarily interested in the design of a basic audio signal generator that
would deliver signals from 20 Hz to 20 kHz using only a
single tuning- control. The output signals produced by the
generator are square, triangle and sine waves.

How the circuit works

A block diagram of the 8038 IC function generator is
shown in Figure 1. The external timing capacitor Cl is
alternately charged and discharged by two current sources.
6

accuracy

- standard.

o +VCc

CURRENT
SOURCE

100 microvolt resolution.

NA/
21

Automatic zeroing. Automatic polarity.

--COMPARATOR

MOS /LSI construction.

OO

O
w
O

E
fr

100

C1eFLIP -FLOP

U_

HCOMPARATOR

V OR

Call Tom Cox collect at 714 -755 -1136 (TWX 910 -322 -1132)

for more details or delivery

GND
CURRENT

NON -LINEAR SYSTEMS, INC.

Originator of the digital voltmeter
P.O. Box N, Del Mar, California 92014

SOURCE 2

SINE

CONVERTERJ'

IBUFFERI.- -+IBUFFERI
9

N./A o

Circle

81 on

reader service card

www.americanradiohistory.com

FIG.
gram

of

BLOCK diawaveform

generator. All elements, except for Cl,

are in the IC.

100K
100K
R5
1K

JUMPER

R9
R8

y..

Cl
0039

C2
0.1

01
1N914A

CALECTRE

R7

3.3K

R4

20K

R2

R1

3.8K

3.6K

ICI

GND/-V

R6

8.2 MEG

NL

ATTENTION

SIG GND / Vcc

HOBBYISTS!
BUILD THIS

DIGITAL
COUNTER/ L.E.D.

P3

FRED
ADJUST

DISPLAY
KIT.

fl*

CALLOUTS IN PHOTO of completed generator show where to

mount parts on the circuit board.

Current source 1 is on at all times while current source 2 is

switched on and off by a flip -flop.
Assuming that, initially, the flip-flop turns off current
source 2, the capacitor is charged by current source 1 with
a current I. As a result, the voltage across the capacitor rises
linearily with time. When the voltage across the capacitor
(which is
reaches the threshold voltage of comparator
set at 2/3 of the supply voltage), the flip -flop changes state
and turns on current source 2 which carries a current of 2I.
The capacitor is discharged with a net current I and the
voltage across it drops linearily with time. As the capacitor
discharges toward a negative peak, it eventually reaches the
threshold voltage of comparator 2 (set at 1/3 of the supply
voltage). When this occurs, the comparator output resets
the flip -flop to its original state and current source 2 is
turned off. At this point, the cycle is repeated.
The triangular waveform, which is developed across the
timing capacitor, is fed internally to a buffer amplifier and
is available for external use at the output pin 3. In addition,
the triangle waveform is fed to a sine converter, which
consists of a non- linear network, for conversion to a sinusoidal waveform. According to Intersil, the typical total
harmonic distortion of the sine wave output is less than 1 %.
With careful adjustment, distortion levels as low as 0.5%
1

are possible.
The square wave output is taken from the flip -flop and
fed to another buffer amplifier, the collector of which is
connected to output pin 9. In this manner, the supply voltage for the square wave output is independent of the rest of
the circuitry and a separate 5 V supply may be used to provide TTL compatibility.

Everything needed to build a complete decade

counter (0 -9) including a printed circuit boat d.
Operates from a 5 Volt D.C. supply. Can to
used in hundreds of applications.

See your nearby CALECTRO

distributor for all the most

popular digital displays and

integrated circuits. Also, get
your copy of the new
CALECTRO DIGITAL
PROJECTS HANDBOOK!

GC

ELECTRONICS

www.americanradiohistory.com

GC ELECTRONICS

DIVISION OF HYDROMETALS
HOCKFORD, ILLINOIS 61101 11: A. CW

CURRENT SOURCES
10K

milScop

74

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R2

(EXT)

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01

40 K

FOUR CHANNEL DIGITAL

HANDHELD MEMORY SCOPE

valuable tool for circuit analysis:

stereo receivers - electronic calculators - digital clocks - digital auto electronics
and more. The MITS MS416- digital pocket
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oriented, handheld scope with full memory capability.
The clock time -base
is from .5 sec. to 200 m sec.
The
scope may be operated in two modes, selected
SIZE: 5Y4
4' x 11/2
by another switch. Besides the normal mode, there is a store mode which
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the time -base range and display it continuously.

Q6

MS -416 is a

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order now for
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Prices,

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WARRANTY:

or

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or

Master

Charge

10

40K

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(EXT)

15K

30 K

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year

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on Entire MITS Line.

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Q7

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STATE & ZIP

BUFFER AMPL

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4.7K

MITS / 6328 Linn, N.E., Albuquerque, New Mexico 87108 505/2657553 Telex #660401

FLIP -FL OP

EIGHT
Circle 82 on reader service card

INSTRUMENTS IN ONE

Out -of- Circuit

Transistor Analyzer
Dynamic In- Circuit
Transistor & Radio Tester
Signal Generator
Signal Tracer Voltmeter
IVlilliammeter
Battery Tester
Diode Checker
Transistor Analyzer

Model
Factory Wired & Tested -$26.95
Easy -to- Assemble Kit -$17.95

212

YOU DON'T NEED A BENCH FULL OF EQUIPMENT TO TEST TRANSISTOR RADIOS! All the
and the radios or other ciryou need to check the transistors themselves
cuits in which they are used
have been ingeniously engineered into the compact,
radio
troubleshooter with all the
6-Inch high case of the Model 212. It's the transistor
features found only in more expensive units. Find defective transistors and circuit
troubles speedily with a single, streamlined instrument instead of an elaborate
hook-up.
r
EMC, 625 Broadway, New York 12, N.Y.
Features:
Checks all transistor types
high or low
Send me FREE catalog of the complete
power. Checks DC current gain (beta) to
value -packed EMC line, and name of
200 in 3 ranges. Checks leakage. Unilocal distributor.
versal test socket accepts different base
configurations. Identifies unknown tranNAME
RE-11
sistors as NPN or PNP.

facilities

2-

FIG.
DETAILED CIRCUIT
waveform generator.

Checks condition of diodes. Measures

battery or other transistor -circuit power
supply voltages on 12 -volt scale. No external power source needed. Measures
circuit drain or other DC currents to 80
milliamperes. Supplied with three external leads for in- circuit testing and a
pair of test leads for measuring voltage
and current. Comes complete with
Instruction manual and transistor listing.

C2
1NF

..L

R1

.6K

DIODE
R5

1K

EMC
N

R3
10K

8038

3
2

lo

FREQUENCY
ADJUST
R4

20K

10012

33K

ICI

R6
2M

ELECTRONIC MEASUREMENTS CORP.

625 Broadway. New York,

R7

R2

3.6K

70NE_STATF__

o'Vcc

D1

DUTY
CYCLE

ADDRESS
CITY

the Intersil 8038 IC

Design
Since we propose to sweep the frequency of the generator
over a 1000:1 range, let's take a look at what determines
the output frequency. Figure 2 shows the detailed circuit
diagram of the 8038 IC waveform generator.
The voltage developed across the two external resistors,
RI and R2, produces two currents to charge and discharge the timing capacitor tied to pin 10. Because this is a
linear system, dropping the voltage across the external resistors from 10 volts to volt will also drop the lower output frequency by a factor of 10. This will increase the output frequency range by 10:1. Lowering the voltage still
further from volt to 100 mV will also increase the output
frequency range by another 10:1. By causing the voltage
across the external resistors to change, say from 10 V to 10
mV, we can vary the output frequency at least 1000:1.
Transistors Q2 and Q3 supply the charging current to the
external capacitor. This current is determined by the
value of resistors R1 and R2, as well as the bias current of

Dynamic test for all transistors as signal

amplifiers (oscillator check), in or out of
circuit. Develops test signal for AF, IF,
or RF circuits. Signal traces all circuits.

DIAGRAM of

11

1Dl0039
TyF

12

o SQUARE

n_n_

o TRIANGLE Wee
SINE

R8
100K

SINE

DISTORTION
ADJUST
R9

100K
o GN D / Vcc

SCHEMATIC

OF THE GENERATOR. Circuit is built around

the Intersil 8038 waveform generator IC.

FIG.

3-

102

www.americanradiohistory.com

Put Professional Knowledge arcl a

COLLEGE DEGREE
in your Electronics Career throlp3h

5K

11.E
10K
5K

33K

33K

Earn Your

33K

5K

DEGREE

10K

by correspondence, while continuing yout present job. No commuting to class. Study 3 your

2.7K

VS,
1K

200
SZ

12

ti

-81K

20

(EXT)
SINE CONVERTER

PARTS LIST
R1, R2 -3,600 ohms, 1/4W, 10%
R3
10,000 ohms, linear taper

-pot,
R4-20,000

ohms, 1/4W, 10%

R5 -1,000 ohms,

R6-8,200,000

trimmer resistor

ohms, 1/4W, 10%

R7-3,300 ohms, 1/4W, 10%
R8, R9- 100,000 ohms, trimmer resistor
.0039 -F Mylar
C2 -.1 -F 25Vdc disc
D1- 1N914A silicon diode
ICI -Intersil 8038CC waveform generator
Power source, case, PC board, wire,
solder, hardware.
The following parts are available from

Cl-

Photolume Corporation
118 East 28th Street
New York, N.Y. 10016
Parts Kit, NOT including case and power
supply
$10.95 incl. postage and
insurance.
Circuit board -$2.50.

own pace. Learn from complete and explicit

lesson materials, with additional assistance from
our home study instructors. Advance as 1.ist as
you wish, but take all the time you need to master
each topic. Profit from, and enjoy, the adv1: tages
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The Grantham correspondence degree pr rgram
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basics, written in very simple language and
continues through the B.S.E.E. degree level.
Throughout the entire program, heavy 1:lphasis is placed on clear explanations written r great
detail, progressing from the simple to tli complex, in easy steps.

Our free bulletin gives complete details In the

curriculum, the degrees awarded, the .luirements for each degree, and how to ern-pH.
GRANTHAM SCHOOL OF ENGINEE.F'ING
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mail me your free bulletin which gives details c.mcerning your electronics degree programs.

Age

Name

Address
FIGA -FULL -SIZE FOIL PATTERN of the circuit
board for the generator.

City
L

www.americanradiohistory.com

State

Zip

Circle 83 on reader service card

--

70

1 03

For

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Apt. No.

Circle 84 on reader service card

transistor Q1. Due to the Vb,. mismatch between transistors

Ql and Q2 (also QI and Q3) and because of the circuit
geometries and current levels involved, the voltage across
the external resistors R1 and R2, with pin 8 connected
directly to +V.,,,, will be 100 mV or more, with a 100:1
sweep ratio. To obtain the smaller voltages necessary for
the required 1000:1 frequency range, the voltage at pin 8
must be raised above -f-V,, . The required voltage difference
need only be a few hundred millivolts, which we can get
without a separate power supply by simply adding a series
diode from pin 6 to the external resistors R1 and R2 (see
Fig. 3). This raises the applied voltage to pin 8 by one
diode drop above -FV,.
The charging current carried by transistors Q2 and Q3
is determined by the impedance between pins 4 and 5, as
well as the bias currents. Any small offset or differential
voltage will cause an imbalance in the charge and discharge
currents and a marked change in the duty cycle. While a
single external resistor is fine for simple circuits, for our
more demanding performance requirement, we use the
separate external resistors RI and R2. By using separate
resistors, we can vary the ratio of the charge -to- discharge
rate of the external capacitor. In this manner, the duty
cycle of the square wave output signal is variable from 2%
to 98% and the triangle output waveform can be adjusted
for either a positive or negative going sawtooth or ramp.
To further lower the output distortion, the voltages applied to pins and 12 are adjusted using two trim resistors
(see Fig. 3). In addition, we can compensate for the remaining duty -cycle error by connecting a high value of
resistance from pin 5 to V,,. which bleeds a small amount
of current away from pin 5 and tends to bring the duty
cycle back to 50 %. With these basic adjustments, we have
a reasonable compromise between low distortion and wide
frequency range.
The schematic diagram of the actual generator circuit
is shown in Fig. 3. The oscillator frequency of the 8038 IC
is set by the value of timing capacitor Cl (.0039 AF) and
1

the voltage applied to pin 8.

New
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FLUKE
e
For data out today,
dial our toll -free hotline,
Fluke
John
Mfg. Co., Inc., P.O.
800 -426 -0361
Box 7428, Seattle, WA 98133
Circle 85 on reader service card

Construction
Construction of the actual audio function generator is
easy. Only a few components are required in addition to
the IC and power supply. Printed circuit construction is
recommended and a foil pattern (Fig. 4) is supplied for
the reader who wants to make his own. An etched and
drilled circuit board is available (see parts list) for those
who prefer to purchase one. While component tolerances
are not critical, the use of a good quality Mylar film
capacitor for Cl is- recommended for stability of the output
frequencies.
All the parts of the generator, with the exception of the
FREQUENCY ADJUST potentiometer, are mounted on the
circuit board. Parts layout is shown in the head photo.
Install and solder all resistors, capacitors and trimmer
resistors on the PC board first. Solder the jumper in place
on the foil side of the board. Next, install and solder diode.
DI , being sure to observe the polarity.
Now install IC1 on the board. We recommend the use
of an IC socket to prevent possible damage to the IC during soldering and to provide for easy replacement in case
it malfunctions. The parts kit which is available (see parts
list) includes an IC socket which consists of two MOLEX
connectors and two plastic insulating jackets. Install the
MOLEX connectors into the plastic jackets and solder the
units to the PC board, being careful not to melt the plastic
jackets with the heat from the soldering iron. After soldering, carefully break off the metal tab on each connector
and install the IC.
The entire generator board with power supply or bat-

www.americanradiohistory.com

VCC* (ON
15V
25011

gill
14)

AT LEAST
4701rF 25V

1/2W

400mW
ZENER

IN4001

OR SIMILAR

2500.1/2W

IH

WHICH ALSO IS
SIGNAL GROUND.

15V
400mW

Vcc-

(ON

CIRCUIT
BOARD)

ZENER
TWO BATTERY

TYPICAL 15 DUAL OUTPUT POWER SUPPLY

FIG. 5 -POWER SUPPLY CIRCUITS, a

b-How batteries can be used.

-A

11

the most

EXTERNAL GROUND

15V

CIRCUIT
BOARD)

+15V

9V

SUPPLY

complete

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pot will fit into a case of the

teries and
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Install the FREQUENCY ADJUST pot and output jacks on
the case and solder leads to the appropriate points on the
PC board. Install the PC board in the case, along with a
source of power and a switch for turning it off and on.
Any simple power supply having reasonable regulation
may be used. But be sure you do not exceed the manufacturer's recommended rating of 15 Vdc or +30 Vdc
of the 8038 IC. The circuit of a Zener regulated supply
is shown in Fig. 5 -a. Batteries can also be used, but they
should be connected as shown in Fig. 5 -b. Two 9 -volt
batteries should supply ample power, but keep in mind
that the unit draws about 15 mA when selecting the
batteries.

ida has
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FIG. 6

DISTORTED

output

FIG.

output.

waveform.

100 -Hz SINE -WAVE

WINEGARD AMPLIFIED
PRODUCTS PROVEN IN OVER
1,000,000 INSTALLATIONS.
CASE IN POINT:

FIG. 8

output.

20 -KHz

triangle wave

20-KHz SQUARE wave

output signal.

FIG. 9

Adjustment
When assembly is completed and you are ready to put
the function generator into operation, apply dc power
to the unit.
To adjust for minimum distortion, connect your scope
probe to the triangle waveform output and observe the
symmetry of the waveform while adjusting the duty cycle
trimmer R5. Adjust the sine -wave next by observing the
waveform and alternately adjusting trimmer potentiometers R8 and R9 for minimum distortion. Figure 6 shows
the distorted sine -wave when the trimmer pot is not adjusted correctly. If you have a distortion meter, you may
use it as a final check on the setting of the sine -wave
trimmers and adjusting them, for minimum distortion.
Check the square -wave output and readjust trimmer 125
if necessary for a 50% duty cycle. This completes the
adjustments of the generator. The actual output waveR -E
forms are shown in Fig. 7, 8 and 9.

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www.americanradiohistory.com

526C

105

COMPUTER TERMINAL
(continued from page 91)

ELECTRONIC
TECHNICIANS!

connected to the computer and the

phone is in the top of the terminal,
you can set your audio level. If the
recorder used has an automatic level
control, use it; if not, record at a "0"
dB level (maximum undistorted level).
To play a tape back, the MODE
switch should be in the IN /OUT position and the playback level should be
twice as high as to cause the CARRIER
LED to light. Make sure the baud rate
is set for the proper data rate on the
recording. The connection to the CT256 stays the same, just change the
connection on the recorder from MIC.
input to LINE out or EXT. SPEAKER.

Raise your professional standing

and prepare for promotion! Win
your diploma in

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We are proud to announce two great
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Circle 88 on reader service card

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Building a one page CT 256 includes parts installation and wiring of

2 large double sided circuit boards,
one medium and one small single sided
board. For a multipage unit there is a
third large double sided board containing up to three additional pages of
memory plus power switching circuitry. First, parts are installed on all
boards. (Be sure to follow handling instructions for MOS chips.) Switches
and connectors are wired to the main
hoard before its installation. Once the
main board is installed in the chassis,
the power supply board is wired in, the
5 volt regulators are installed and
wired, and wiring to the acoustic
coupler board completed (the kit
comes with the acoustic coupler board
assembled, tested, adjusted and ininstalled in top cover of main case).
Next, the switches, connectors and displays are mounted.
The keyboard assembly should be
completed at this time, including assembly and wiring of keyboard connector and cable.
After a final wirilig check and inspection for solder bridges, connect
keyboard to main unit, connect self
scan display to the main board, and
set MODE switch to LOCAL. Connect to
a 115 Vac power source and turn
power switch to on. The page 1 LED
should light, and characters should be
entered from the keyboard. If problems arise, isolate the problems and
analyze them using information from
the text and diagrams. An oscilloscope
is indispensable in trouble shooting this
type of circuitry.
The following items are available
from MITS, Micro -Instrumentation
Telemetry Systems Inc., 6328 Linn,
N.E., Albuquerque, NM 87108.
Complete kit of all parts
$495.00
Kit less cabinet & power supply $395.00
Assembled Terminal
$695.00

Circle 89 on reader service card

www.americanradiohistory.com

TABLE OF CONTROL CHARACTERS

AND THEIR FUNCTION IN CT256
Control G -Bell signal-used to alert
operator
1/2 second
-kHz
audible tone.
Control H-Backspace--moves data in
display one position to the
right -does not change data

-a

in memory.

I-Advance space -moves data

Control

display one position to the

left-does not change data
in memory.
in

J-Control

character for linefeed. Since it has no mean-

Control

ing in the CT -256 it is de-

coded and entered

into

memory as a space.

COLLECTORS!
We've just added the 1927

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The original Supreme Publications books. Schematics of
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1926.1938 volume, 600 models, 57.00.
1941, 42, 46, 48, 49, 50, $4.00 each.
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Control

K- Home -homes

memory ad-

dress counters to cursor

position.
and clear -homes
memory address and clears
page.
Control M- Control character for carriage return -has no meaning for the CT256. It is decoded and entered into
memory as a space.
Control N -Control character for cursor up -has no meaning for
the CT256 and is decoded
and entered into memory as
a space.
Control 0-Address function-sets up
receive circuitry to use the
next two characters to shift
data address to a selected
line and position. (See explanation of address function.)
Control L-Home

20

70 Power

Microscope
Pocket -size 20 to 70 power 'scope gives you
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Comes with tripod legs, pen light, zipper case.
a

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Magna -Lites

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MAGNA -LITE, with new high power lens, lets
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bathes magnified area with just the right amount
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Ask for FREE Tools Catalog

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C. H. MITCHELL CO.
14614 Raymer St.

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Circle 90 on reader service card

COMPONENT
LEAD
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Eliminates trial and error lead bending.
Fast, exact, thumbwheel adjusted spacing
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"Breezes" through special units and

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Circle 92 on reader service card

DEFINITIONS FOR
SWITCHES AND CONNECTORS
CT256 KEYBOARD
Special Key Functions (Top Row of
Black Keys)
P-] Shift left-Moves data left one
position (advance).
[H] Home -Returns data to 0, 0 posi-

tion.
[ -.] Shift right -Moves data right one
position (backspace).
[A] Address-Three keystrokes are
necessary to select an address
(an exact position on a page). Operator goes to desired position on
the page by pressing [A], then
presses the specific key for line
position (1 -16), then presses the
third key which selects data position in the line (1 -16). Characters
are not entered until address sequence has been completed.
[C] Clear-Clears page and returns
data to 0, 0 position (home).
[T] Transmit -Automatically transmits
character in cursor position to
computer and is used to transmit
information line by line from the
terminal memory to the computer.
Since the terminal memory does
not store carriage returns (end of
line), the
symbol (shift [P])
is placed in memory at the end of
each line. The " @" symbol stops
transmission and the operator can
manually press "return" to indicate end of line.
Other Special- Function Keys
Rept
Repeat- Causes a character to
be entered repeatedly. Press
character key and Rept. key.
Rub
Deletes previous character.
Out
When working with computer.
Shift
Allows entry of upper -case
characters indicated on keytops.
Press shift, then upper -case
character desired.
Ctrl
Control- Allows entry of special
control signals to computer,
i.e., Ctrl and G is bell signal.
INDICATORS on FRONT of CT256.
P1 -P4 Indicates page displayed.
Carrier Indicates when 2 -kHz tone is
received from computer via telephone
or tape recording.
R -E

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107

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SIMPLIFIED COMPUTER PROGRAMMING -THE EASY RPG WAY,

by Kelton Carson. TAB Books, Blue Ridge Summit, PA 17214.
240 pp. 812x51/4 in. Hardcover $8.95; Softcover $5.95.
A computer, being a very complex system, requires literally
thousands of steps and instructions to perform even a simple operation. The instructions are provided by a program which may be
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left for the programmer is to write a few instructions in a few
simple forms. The computer then translates the simple people
language of the forms to the complex machine language of the
computer. This book shows how it's done.
RESISTIVE AND REACTIVE CIRCUITS, by Albert Paul Malvino.
McGraw-Hill Book Co., 1221 Avenue of the Americas, New York,
NY 10020. 592 pp. 91/4x71/4 in. Hardcover $12.95.
A comprehensive textbook that provides all the information needed to prepare a technician for more advanced electronic courses.
The first part of this book discusses resistive circuits with dc or ac
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complex numbers. The final section of the book which does require
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SOLID -STATE IGNITION SYSTEMS, by R.F. Graf and G.J. Whalen.
Howard W. Sams & Co., Inc., 4300 W. 62 St., Indianapolis, IN
46268. 136 pp. 81/4x51/4 in. Softcover $4.50 (in Canada $5.40).
Solid -state ignition is a fact of life in the modern car. There are
many types of systems reflecting the various schools of thought
about what constitutes the ideal solid -state ignition system. In this
book, you will find all the known commercially available methods
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all are presented here in great detail. The first chapter describes
the phenomenon of spark ignition in easy -to- understand terms. Chapter two then relates how the conventional ignition system produces
a spark. Chapter three covers semiconductors and how they are
used in ignition systems. Chapters four and five give complete details on existing systems. The last chapter provides data for servicing and troubleshooting modern electronics ignition systems.
HANDBOOK OF MODERN SOLID -STATE AMPLIFIERS, by John D.
Lenk. Prentice -Hall, Inc., Englewood Cliffs, NJ 07632. 414 pp.
91/4x6 in. Hardcover $15.00.
Here is a detailed treatment of both the theory and practice of
modern electronic amplifiers. It is perhaps the most comprehensive
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technician level featuring simplified guidelines for practical design,
complete test procedures and practical troubleshooting techniques.
The book describes all types of amplifiers in common use -audio,
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TTL COOKBOOK, by Donald E. Lancaster. Howard W. Sams & Co.,
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In mid -1972, an electronic revolution took place. For the first time,
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www.americanradiohistory.com

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1.05

28 PFN.
36 PIN.
.

40 PIM

wire wrap sockets - 1/2/3 levels wbE'

large volumn DISCOUNTS

.45
.45
.25
.23
.27
.32
.27
.31

.32
.40
.33
.26
.45
.50
.50
.23
1.10
1.05
1.10
1.15
1.10
1.25
1.25
1.25
.25
.27

Announcing Music Associated's new solid

state sub-carrier detector for reception
of "Music Only" and other "Hidden"
programs now broadcast on FM. Unit has
built in AC power supply, excellent muting and no cross talk. Use with any FM
radio or tuner. A quality product. Wired
only (Bakelite case) $79.95. Special model for cars (batteries included) $79.95.

65 GLENWOOD ROAD
UPPER MONTCLAIR, N.J. 07043

Phone: 201 -744-3387

..

74157 $ 1.55
74160 1.65
74161

1.65

74163
74164
74165
74166
74170
74173
74174
74175
74176
74177
74180

2.50
2.50
2.50
1.75
3.00

call for

74182
74184
74185
74187
74190
74192
74193
74194
74195
74196
74197
74198
74199
74200

cold;
C DSC&

.7t

COSO:
C a113:
74d:0D
741:04
744:20

741:1'1

601I Series
80110
$ .35
80. 1- 2098 .55

5.00
.75
1.15
1.35

02
82HC
821t8
E8r:C

Nap- Other
800: Series

2.25
2.75
7.00

LI

3S

MF

PROJECTS
8263 Sig. 7.00
8267
4.00
14.00
2513
2518
7.00
7.00
2424
2425
7.00
4024
2.25

Mt S<
Ml ari24
Mi.N
rA.N
M&.N

Dl

Above

I
I

'

31

Series_

4CI

,0,
15/1.00

I0/1.00
6/1.00
5 /1.00
3/1.00
1.25

Comparators
2 Watt Audio AMP

MM7103
2519
2529

40 X 6 Static Shift Register

240 X 2 Static Shift Register

1.00
1.25
.55
.65
3/1.00
7.95
11.95
2.00
3.95

Ouad AMP DIP

LM3900N
Precision Timer
LM3905N
LM741CH /LM741CN OP. AMP.
24 Pin Digital Clock Chip
MM5314
MM5316
40 Pin Alarm Clock Chip
MM5016H
512 Bit Dynamic Shift Reg.
1

5/1
6/1
5/1

1.95
.95
1.95
1.50
1.95

Mr.N

LM38ON

1024 X

.55
.55
1.50
1.40
.55
.55
1.25
.60
.45
.70
.65
2.60

C0101E

1.50
1.50
1.50
1.50
1.50
1.05
1.25
1.05

.60

CD-101?

.85
.85
1.05
3.75
1.00
2.30
2.30
7.00

74191

1.40

CD401C
C17401,

CD401

1.75
1.85
1.85

74181

CD40:9

Bit Dynamic RAM

4.00
5.00

LINEAR
LM300
LM301H /N
LM302H
LM304H

Pos. V Reg
Improved Op Amp

$ .85

To 5

.40
.85
1.10
1.00
.40
1.15
1.70
1.35
1.15
1.55
1.75
1.90

Voltage Follower
Negative Voltage Regulator
Positive Voltage Regulator
Op Amp (Super 741)
Micro Power Op Amp
5 Volt Regulator / Amp
Improved Volt. Follwer Op Amp
Hi- performance Volt. Comp.

LM305H
LM307H /N
LM308H /N
LM309K
LM31OH
LM311 H/N
Hi-Speed Dual Comp.
LM319H
LM320K- 5V -15V To 3 Neg. Regulator
Quad 741 Op Amp
LM324N
LM339
Quad Comparator
LM34OK- 5V- 12V- 15V -24 Positive Volt Regulato,
A 6 C - Squelch Amp.
LM370N
AM /FM $$ B Strip
LM373N
2 Watt Audio Power Amp
LM380N
RF /IF Amp
LM703H
Dual Op Amp
LM5558V

2.35
2.00
1.55
3.30
1.50
45
1.00

LM741H /N
Comp. Op Amp
.40
LM747H /N
Dual Compen. Op Amp
.90
LM748N
Freq. Adj. 741
.40
LM1458N
Dual Comp. Op Amp
.65
LM3065N
T.V.-FM Sound System
.75
LM3900N
Quad Amp
.65
LM555N
Timer
1.00
LM565- LM566 -LM567 Phase Looked Loops
2.50ea
LM 7522
Core Memory Sense Amp.
2.50
Core Memory Sense Amp.
LM 7524
1.50
1.00
LM 7535
Core Memory Sense Amp.
LM75451
Peripheral
.49
Dual
Driver
LM75452
.49
Dual Peripheral Driver
LM75453
Dual (LM351I
.65
Satisfaction Guaranteed. All Items 100%Tstst
No Extra Chirp
$5.00 Min. Order 1st Class Mail
Add 6% Sales fie
California Residents
Wholesale Outlets Write for Special 0isln1 EE S
Data Sheets .20 ea it
Write for FREE Catalog

Ir

JAM4,I
Electronics

P.

0. Box 822
PHONE

- Belmont,

Ca.

94002

ORDERS WELCOME

(415) 592-8097
Circle 104 on reader service c,i,-

www.americanradiohistory.com

$ .55
c0+10:
.55
C040C 2

$PECIAL$

LM311H /LM311N

1.30
1.55
1.75

CP OS

7453 $ .27
.40
7454
7459
.25
7460
.25
7470
.45
7472
.41
7473
.47
7474
.47
7475
.90
7476
.47
7480
.50
7482 1.75
1.15
7483
1.10
7485
7486
.47
7488 4.00
7489 3.00
7490
.89
7491
1.15
.95
7492
7493
.95
7494
.97
.95
7495
7496
.95
1.50
74100
.47
74107
74121
.55
74122
.47
74123 1.05
74125
.60
74126
.80
74141 1.15
74145 1.15
.95
74150
74151 1.20
74153 1.50
74154 1.25
74155 1.30
74156 1.30

IN4148 Silicon Signal Switching Diode

TIS97 - TIS98 NPN Transistor
7400 - 7401 7403 GATES
7404 - 7410 - 7420 GATES
LM301H /LM301N OP. AMP.
5 V 1 AMP
LM309K

MUSIC ASSOCIATED

telephone licenses Newly revised multlpleTest

7442
7443
7444
7445
7446
7447
7448
7450
7451

.23
.23
.23
.25
.24
.50
.50
.25
.25
.23
.30
.89

tot

Vinyl Repair Specialists /Dealers!

Sensational opportunity available! Operate your
own profitable business. Write today!
Now needed

20% Discount for 100 Pieces Combined

'500 WEEKLY
EASY!
OR MORE
TA

7400 $ .18

BUSINESS OPPORTUNITIES

EARN

T T L

7441

CONVERT any television to sensitive, big screen oscilloscope. Only minor changes
required. No electronic experience necessary. Illustrated plans $2.00. SANDERS, Dept.
A -25, Box 92102, Houston, TX 77010
FREE catalog. Most unusual electronic kits
available. Music accessories, surf, wind
synthesizers, wind chimes, many others.
PAIA ELECTRONICS, Box B14359, Oklahoma
City, OK 73114
PLAY ping pong on your TV. Plans $3.50
complete units info 25c. D. DUNCAN, 20650
Runnymede, Conoga Park, CA 91306

...
Also available

CLASSIFIED COMMERCIAL RATE (for firms or individuals offering commercial products or

services). $1.15 per word ... minimum 10 words.
NONCOMMERCIAL RATE (for individuals who want to buy or sell personal items) 70c per
word ... no minimum.
FIRST WORD AND NAME set in bold caps at no extra charge. Additional bold face at 10c
per word. Payment must accompany all ads except those placed by accredited advertising
agencies. 10% discount on 12 consecutive insertions, if paid in advance. Misleading or
objectionable ads not accepted. Copy to be in our hands on the 26th of the third month
preceding the date of the issue (i.e. August isue closes May 26). When normal closing
date falls on Saturday, Sunday or a holiday, issue closes on preceding working day.

PLANS & KITS

109

1103 7- Segment
1E

7400

Readout

-PIN DIP

Three digits with right -hand decimal

a Plugs into DIP sockets
e Similar to (LITRONIX) DL337
n Magnified digit approximately .1"
o Cathode for each digit
e Segments are parallel for multiple
operation
u 5 -10 MA per segment
EACH $3.00
4 (12 Digits) $11.00

7400
74H00

POTTER &
BRUMFIELD
Type KHP Relay
4 PDT

24 VDC

120 VAC

3A Contacts

(650 coil)

$1.50

EA.

(10.5 MA coil)

$1.75

EA.

40 -PIN SINGLE CHIP

Add, subtract,

multiply, and divide

12 -Digit display and calculate
Chain calculations
True credit balance sign output

u
o
o

Automatic overflow indication

o Fixed decimal point at 0,2,3, or 4
u Leading zero suppression
DATA ONLY (refundable with
purchase of chip)
$1.00
COMPLETE WITH DATA
$6.95
a

RCA 2010
Numitron Digital Display Tube, incandescent 5 -volt 7- segment:
.6" High numeral visible from 30 ft
Standard 9 -pin base (solderable)
Left -hand decimal
EACH $5.00

point
5

FOR $20.00

CD -2 COUNTER KIT

Unit includes board, 7490, 7475, quad

latch, 7447 seven -segment driver, and

RCA DR2010.
`

76917w71-

COMPLETE KIT only$11.95; FULLY- ASSEMBLED $15.00;

boards can be supplied
separately at $2.50 per digit.

KEYBOARD ASSEMBLY
TRW Data Systems unit; 10 keys 0 -9; 3
(or 4) 2 4 V lamps; printed c i r c u i t
board w /14 1N4001 diodes, capacitors,
transistor, and resistors.
All mounted in an attractive case approx. 41,
x 4% x 21/2".
These are used; no schematic is available.
EACH $6.95

NE560....
NE561....
NE565....
NE566....
NE567
TO-5...
709
710

3.25
3.25
3.25
4.00

748

CA3018

CA3026
CA3045
LM100
LM105
3.00 LM302
.45
LM308....
.75
LM311....
711
.40
LM370....
74i
.55
LM3096...
747
$1.50 LM309K...
LM1595 4-quad. mult.

LED's
11V

$1.00
1.00
1.00
1.00
1 00
1.25
1.25
2.00
1.75
2.00
1.00
2.00
$2.00

-50 Red Emitting

2V

10 -40

:1A

$20; 00810.00

1.20
1.25
1.50
.25
.35
.25
.30
.35
.20
.25
.35
.35
.20
.30
.40
.50
.60
.75
.65
.80
.60
.80
.65

1.00
4.00
1.20
.90
1.15
1.15
2.00

EACH..$ .45
10 FOR $3.50

CMOS

SEND FOR
FREE FLYER!

1-

o
w

10 FOR

$8.95

TRIAC
296344 600V 8A TO220....EACH 5.75

-J

w
O
o
Q

110

all in one DIP

5.75

C.O.D. PHONE ORDERS

ACCEPTED --$10 MINIMUM

AYLOlrl
ELECTRO111CS

USE

(Specify frequency range)

FE /RE 52, JAI, 2, or 3 series,
25 -50 MHz. 12 volts, 35 watts,
front or rear mount, fully solid
state receive, 3 tubes in transmitter, fully narrow band. complete with accessories

ZIP
CODE

P.

O.

Box 41727

Sacramento, CA
95841
(916) 334 -2161

receive.

tubes in transmitter,

with accessories

(specify frequency range)

FE /RE 72, JAI. 2. or 3 series,

FE /RE 73. JA6 series, 150 -174

MHz, 12 volts, 80 watts, front

or rear mount, fully solid state

receive, 3 tubes in transmitter,

fully narrow band. complete

with accessories

$29800

$28800

all
mail

fully narrow band, complete

$19800

front or rear mount, fully solid

state receive, 4 tubes in transmitter, fully narrow band, complete with accessories

on

FE /RE 53. JA6 series, 150 -174

MHz, 12 volts, 35-watts, front
or rear mount, fully solid state

$1780
25 -50 MHz, 12 volts, 100 watts,

CMFT50, 25 -54 MHz., 12 volt,

50 watts, transistorized power
supply, partially transistorized
receiver. fully narrow band with

R.C.A.

n
t

$12800

accessories

GREGORY ELECTRONICS CORP.

251 Rt. 46, Saddle Brook, N. J. 07662
Phone: (201) 489 -9000

FREE bargain catalog. Transistors, computer

boards, LED's thermocouples, parts. CHANEY'S, Box 15431, Lakewood, CO 80215
MANUALS for Govt. surplus radios, test
sets, scopes, list 50c (coin). BOOKS, 7218
Roanne Drive, Washington, DC 20021
DYNACO -A-R, transistors, repairs -boards-&
units, speaker service. Send for prices 8
details: BEAR ELECTRONICS, 177 -R Hill crest Road, Mt. Vernon, NY 10552

BUILD A 'SPACE -ACE- TV CAMERA!!

,111

UNIQUE

KITS

CANADIAN
ELECTRONICS
CATALOGUE
S1.00
(refundable on 1st purchase)

featuring
SINCLAIR hi-fi modules and calculator
kits. We will include the new 32 -page

Project 80 hi -fi module construction

manual.
AMTRON electronic kits -over 100 types!
'Speaker kits and components
American enquiries welcome!

OL3DSTO11E ELECTRO/UCS
1

PHONE or WRITE for CATALOG

non 453 -RE

ATV

Research

DIAL

402.947.j771-

736 AVENUE RD.,TORONTO,ONT.

M5M 3Y7. DEPT. RE -11

DAKOTA CITY NEIIR. 88731

LIQUID crystal. 31/2 digit wristwatch display.

New, with instructions for building wristwatch. Final close -out. Less than original,
factory wholesale price. $5.50 each. Two for
$10.00. TRICOUNTY WINSLOW, INC, Box
5885, Grand Central Station, New York, NY
10317

ELECTRONIC Ignition: Capacitor, transistor,

pointless. Auburn

Amplifier -Limiter, FM Detector,

Electronic Attenuator, Audio Driver
IF

Its new and fully-tested; leads plated with

gold or solder. Orders for $5 or more are shipped
prepaid; smaller orders add 5511. California residents add Sales Tax. Its shipped within 24 hours.
A

service

SPECIAL!

O
Q

GENERAL
ELECTRIC
T.P.L.
SOLID STATE
TWO -WAY
RADIOS

723

op

faster

Power Supply

DIP
variable
regulator chip 140V, + or - output
@ 150 MA l0A with
external pass transistor- -with
diagrams for many applications
EACH
$1.00

The FM Used
Equipment People.
SEND FOR NEW 1975 CATALOG

.70

CA3065
MAN-3 Seven -segment readout:
EACH ONLY
$1.25
10 OR MORE, EACH
1.00
MAN -1 LED Display
3.25
MAN -4 Seven -segment 01P $2.75

For

1.20
1.25
1.50
1.00

F amp
epoxy TO -5.

GREGORY ELECTRONICS

EuE:
GE

1.40

CD4001....$ .75
CD4 02....
.75
CD4011....
.75
.75
CD4012....
CD4023....
.75
74C20
.75
74C160
83.25

100/810.00
MV5024 Red TO -18 High Dome @
2V $.35; 10/$2.95
MV -10B Visible Red 5 -70 MA @2V
(^h-$.30; 10/82.50

.20
.35
.35
.28
.35
.28
.70
.35
.35
.25
1.25
.40
.25
.35
.35
.35
.25
.35
.40
.25
.35

1M703

SEGMENT READOUT: First -quality, made

by H- P, Lh -hand decimal point, segment
pin -out same as MAN-1, common anode.
EACH $1.75
SPECIAL 10 FOM $16.00

LINEARS

7408
74H08
7410
7413
7417
7420
74120
74620
74622
7430
74630
74130
7440
74H40
7442
7441
7447
7450
74H50
7451
74L51
74651
7453
7454
74L54
74L55
7460
74L71
7472
74L72
7473
74L73
7474
74674
7475
7476
74L78
7480
7483
7489
7490
7492
7493
7495
74L95
74107
74145
74180
74193
74195

ppE001gy. :

.25
.35

RF -I

7-

NE540....$2.00
NE555.... 1.50

7401
7402
74H01
7404
74H04
7405
7406

DIP
$

sparkplugs.

Information

10c. ANDERSON ENGINEERING, Epsom, NH

03234

PRACTICAL applications of digital IC's.

100's of tips, circuits, projects, on TTL. 443
pp. $19.95, money back guarantee. GEA,
P.O. Box 285, Northfield, OH 44067
EXPERIMENTERS! Projects and theory in
digital computers including high speed I/O
terminals, morse code converter and display. Send for free listing. EXPERIMENTER'S
LIBRARY, Box 2367, W. Lafayette, IN 47906.
INTEL 8008: $59.45; laser diode, 6W, GaAs:
$10.25; liquid xtal, 31/2 digit, .4 ": $9.75; 8038
vco: $5.95; Intel 1101: $1.95; 1103: $3.00;
8223 ROM: $4.95; Catalog: 10c. ELECTRONIC DISCOUNT SALES, 138 N81st St.,
Mesa, AZ 85207

Circle 99 on reader service card

www.americanradiohistory.com

EQUIPMENT REPORT
(continued from page 26)

tons for REW, FF, Play, Stop, Record

Interlock and Pause.
Performance: Using Maxell UD
tape (specified by Panasonic) with
the Dolby operative, the record /play
frequency response was 3 dB from
30 to 13,500 Hz. Distortion at the
indicated 0 -VU record level was 0.8%
THD with 6 -dB headroom to 2%
THD (tape saturation). The signal
to noise ratio referenced to 2% THD
was 57 -dB widehand, 64 -dB narrow band.
Wow and flutter was outstanding.
The value, through record and playback, was 0.06 %, like that in "the
R-E
best" reel to reel recorders.

POLY PARS

7- SEGMENT

LED Readouts
4

MAN -3 -SLA-

Each

Char.

Type
MAN -1
MAN -3
MAN -4

$3.75
1.49
2.50

.27

.12
.19

my!
LOWEST PRICES!

Special

for $6.

"ULTRA BRITE"

XCIT'ON .LEDS
$2.50 139.pe - kit

-1
-3

.33*

'

2.50

ultra -brite offers at "dull"

Prices: Kit includes: 3 REDS.

8 WATT STEREO
AUDIO AMP

3 GREENS,
3
YELLOWS,
each
including JUMBOS.
MEDIUM and MICROS.

By Opcoa

MR

2 -MV2, TO -18, dome, green, visible

2 -MV2, green small dome, green Jiff. lite
MV3, micro-mini 'pin head' dome, TO -18, green

1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.96
1.00

lite

....

lene,

tas
1.49
1.00

Dollar Stretchers

SI

2- Sylva:la 18,000V Matchstik TV rectifier, 4" x Ve with leads

E11900 TRIGGER DIODES for SCRs A Triacn
S
N channel 6000 umbos, TO 92 plastic
2
FET'S
10
iHSi4 fut switch diodes, silicon, 4 nanoseconds
2 -G AMP TRIAC 200 PRY TO -6
silicon porcelain to lEV
40- ITT MICRO MINI RECTIFIERS
L aeners, 1W, assorted volte
30- WORLD'S SMALLEST RECT.
4
2N42S9 Nixie tube driver transistors 100V, npn
2 -45000 Ply 60 mil epoxy ectlflers, axial leads
10- BENDIX 25 WATT "pellet" power transistors, silicon
4 -BO WATT, 2N1456, silicon, T03, 60 Vco, npn
2N11036 NI -PWR plastic trans 100 viceo, 7 amp 85 watts
14 2N3296 HOBBY, 35 watts, plastic powers, NPN
2N61O9
, 40 watts, plastic powers, PNP
PLASTIC 35W power., spin, silicon, hobby 2N121
3
6
PLASTIC 3W powers, pnp, silicon hobby 2N8124
2
MOI VETS, N channel 10K umo. 35128, TO -18. RCA
2 -MOs FETE, DUAL GATE, N chan. 35187, TO -18. RCA
2 MOS VETS, DUAL GATE N chan..3N140. TO.18. RCA
4 RCA 2N3600 NPN, UNEF transistors, tv -fm. TO-18. I000mc
2
MPF -1000, Motorola MOS dual gate "The Claw ".
2N56513 200 hfe, 250 viceo- Dower tab $1.,
2

4--

---

-I.C. & LED HOBBY -ONICS

Si.
SI.
Si.
SI.
Si.
51.
Si.
Si.

....

....

-1

-3

. 2-

MAKE YOUR OWN

CALCULATORS
WITH OUR
LOW PINCED
Year Choice

6 -8 -12
DIGIT $16.95
CALCULATOR BASICS

THREE QUARTER
INCH DIGITS
BY OPCOA

for $13.

Coisr

Typo
SLA -3H

RED
RED
GREEN
GREEN

SLA -4H
SLA -13
SLA
SLA -23
SLA

30 mile
Order by type

-14
-24

number

Plus

$3.98

YELLOW
YELLOW

"IC ", with

pair of complimentary 35watt plastic transistors, i.e. 2N5296 npn
and 256109 pnp. With schematics. printed
circuit and parts board layouts.

LOWEST PRICES ON NATIONAL

"CALCULATOR.. CHIPS"
3 of Si
.55.9$
12- Digita, 40 Pin
7.77
9 -Volt veraion of 6001
9.99
12- Digits, 28 -Pin
with 3- function memory.
MM5725 E- Digita, 4- Funct. LED 4.95
4.95
61148736 6- Digits, 28 -Pin. 9V
CTS001

CT5002
CTS005

tor TO-36, germanium.

VCBO
160
we its,
PNP
ror
N0V, 16 amps. 40
ignition, gh power trans.

Itte,

51.

Si.
Si.
Si.
Si.
Si.
SI.
Si.
$1.
Si.

Mounted

etc.
6

x 21/2

t/

$1.49

heat sink

on

NEW!
NATIONAL
LM -340T VR's

SENSE CORE
LM -7620
L1 LM -7521
p
LM -7522

MEMORY AMPS
LM -7523
LM -7525
LM -7824
LM -7529
LM -7525 Q LM -7535

3 .er 112.

3.or

Buy 3
take
107E

-OST,

OAK FEATHER -TOUCH

LM.340
340 -12712 e

DIM-340-15715
LM- 34.167!!e
LM- 340.247 4

v
v

Tai. low

CRYSTAL OSCILLATOR
Rare buy of

popular
precision modules that are
these

by hams, clock enthusiasts,

hobbyists.
By
Monitor, Type 850. Free.
4.000 MHz. Accuracy tt.
.001. Requires 5VDC. Gen states a
wave
ave on
x
output. Size: 11/4
1
/2

"

4x

nd `letter.
changed. 2/

Characters

2
se
4s

''Et

r."

I_
1

I7

Kit of 17 for $4,95

$4.95
only
m type 0 -to-9
above
D

.s

easily
" high. D 5
asp,
Printed
6.17
white characters. White circuit.
top, block numbers.
7(1

t Blue

CALCULATOR'S
KEYBOARD
SWITCH KITS

used

3;for SI :I51aai

._

s
-L
$1
7 .75
Each
Your Choke

Buy 3

`4

SWITCHES
'FOr
RTTY
Printed
Circuits Mfs.
OAK (Ham's note,
Par Unique Panel RrTY,bytao)
dot systems,
e u used
Switches
Keyboard
Calculator, SPST. Normal!,
Open, 24V 1 amp

5
v

IB]

!Volts
6 v

112.

95* ei

1 Amp
POSITIVE VOLTAGE

reps

et 521.
f 527.

....

TO- 220!C.a

LM- 340.05T
LM.340.06r

tch

n,

ams.
switch d
Wild Rover Keyboard
Sal. $24.95
K y ;arts
12 DIGIT BASIC "MEMORY" KIT /PS
my for 4- memory calculator. Case with 'slight total
0' OFF
board". CT6006 memory chip, 6 MAN 3'e, is
pc
itch, book, (extend key allows 12 dig
boards) 519.95

For Class AB use. Basic includes: Signetic

540 30 transie for high power driver TO -6

Si

'l

decimal

networks,
with ON -OFF

2- resistor

case,

carrying

AMPLIFIER BASIC

.001
Key parts include.
12 DIGIT BASIC N4
chip, 4 -3 digit readouts, factory etched PC boast, vase,

or Minas on

for

3S WATT AUDIO

51
51

{e
includes case, all- function h'
BASIC KIT 51
Keyboard, Cal Tech CT6002 calculator chip,
Ante. LED display with built -on individual ma, ni an.
Plus sheets.
me as Basic Si except ca rr ,cor
BASIC KIT 52
chip is National 8 -digit MM5726.
KIT
g3
same
as Basic j1 except, .2a r r ,tor
B ASIC
chip is National 6 -digit MM6'736 and 76492.

O to
0.7 en...aetsr

HIGH POWER
s f.. 53
ISTOR
new
WITH
ment!`ncudeo`
HEAT SINK
2N174 'doorknob' transis-

4 -DUAL 709, dip pak, op amps, untested

..
10 RCA C3000 OP AMPS. TO -6 case
LOCK LOOPS, hobby 665, 680, 561
sta.TO.S Case 536 640, 565 567, 741
Ill! 10- LINEAR AMPIE, 709, 7I, 711, 741, TO -6
Si.
AMPLIFIERS, Westinghouse. Rol -5
o 3.1 -WATT AUDIO
up to 16 -cell, DIP
Si.
5 -HOBBY MEMORY CELLS,
SI.
REGISTERS, 501 to 6017, TO-5, MiniDIP's
0 5-MOS
51.
10 - C" NOS IC's, 74C and CD4000 saes, DIP pak
Si.
DI10 -MINI DIPS. OP AMPS, 709, 741, a301, 907, hobby'
10- SIGNETIC OP AMP. 531, 539, 638, 550, 666, DIP., TO -5 I.
-28
-pin.
24
-or
51.
1
-6311.14 CLOCK ON A CHIP, 4 -or -6 digit,
Si.
1
- CALCULATOR ON A CHIP, hobby, exp. 40 -pin, specs
$1.
2 -2516 CHARACTER GENERATORS, hobby, for MAN 2..
'Si.
aj. 2613 CHARACTER GENERATOR, Hobby for MAN -2
Si.
5 -IBM IC' with pc board, many parts, from computers
Si
DIP. u test 'em
1 -AM RADIO.ON -A -CHIP, by Sprague,
4 -DUAL 2-WATT "Steno- Amp- On- A- Chlp ",falloutlSprague, utest,31.
Si.
-more
sego
1
-or
MAN
-6,
green,
gone,
-11,
like
SLA
2.OPCOA
2 -OPCOA SLA -3H, 0.7 chase. readout, 1 -or -more seg. missing. Si.
fl- MONSANTO opto isolators. no test, 1500V
10 -LED HOBBY SURPRISE, asst. types. factory rejects, no Cott Si.
MAN -1, red, .33" charm. 1 -or -more sego gosS1.
2.OPCOA SLA
2- MONSANTO MAN -4, .19" harac. 1 -or -more emirs missing. red SI.
or more sees missing. SI.
5- MONSANTO MAN -3, .12" charac, red.
Si
2
-DIGIT NATIONAL READOUTS, some digits good.
10- SPRAGUE- DIPS, LINEAR OP AMPS, 2111 aeries. 2120 eerie. .$1
51.
1-MAN-3, "THE CLAW ", one dot missing, 100% perfect
hobby
..
a
Chip,
S1.
MM6736 6 -Digit Calculator on
SI.
10- FAIRCHILD- NATIONAL, 9000 Series ICs, dips, hobby...

4--

.50
DIP
6 or 10 -Pies. .29
-eon (Mlsl DIP) .31i
14 -Pin, Win Wrap
16 -Pin, Win Wrap ...floc

TO -S,

7 Segments

$1
$1

miceoo

.....

016 -Pin,

Buy Any 3
Take 107.

SOLID
STATE

gicIlGlaeoLO sF

14 -Pin, Side Mount 1.00

--

INTEGRATED CIRCUIT
SOCKETS
....5.45
1] 14 -Pin. DIP

5.95

AMPEREX

Musical instrument amplifier at low, low price! Peak

power output 10 watts. Two input circuits are equaliced for normal or solo guitar. The four controls are
VOLUME, TONE. TREMOLO INTENSITY and TREMOLO
SPEED. There are terminals on board for normally open
foot witch connection. Supply voltage 18vdc. Output
to 8 ohm hi- quality emeaker. Input impedance 39,000
ohms. Current drain 20 mils. External power supply
required. Wt. 1 Ib. With instructions. hookups and
diagrams. Size 8 a 2s/e x 3.

I.

SI
SI
Si
SI.
1.
11.

Si.
Si.
Si.
Si.
Si.
Si.
Si.
Si.
epoxy, submini, silicon rectifiers
B- 1 -AMP 1000 PIV,axial
Si
4, 6, 9, 10, 12V rectifiers
30 - 600MW
Si.
4 - 2N3065, HOBBY 40W po silicon transistors, TO-3
Si.
30 - 3-AMP RECTIFIE RS, silicon, epoxy, assorted V.
type"
V
"comb.
RECT.
1000
St.
2 -EPDXY 2 -AMP SILICON BRIDGE
,

4 WATT GUITAR AMP

$1

1.5316 CLOCK CHIP, hobby

2.5006 MEMORY CALCULATOR CHIPS, 28 -pin HOBBY
S -555
TIMERS. mini DIP, hobby
10.741 OP AMPS, mini DIP HOBBY
2255295 35 -WATT NPN PLASTIC TRANSISTORS; UM- NE=540
4Q_W_AT7 PMP PLASTIC TRANSISTORS, for NE840
2 -261QE
NB2
lIii-1116-2 GERMANIUM UHf diode, clip-in type
6 -SCRs 7 -AMP T0220, 6 -12 -24 prv, power tab
O 10 -MOs VETS, SN187, 3N200, 3N128, TO-18. Fairchild
5 -SCRS A TRIALS up to 25 amps. 6 -12 -24 pry. studs too
2 - 2NfB19, Texas, N charnel, 6600 umiio TO -18
plastic transistors, Texas
8 2 - 2N204 UNIJUNCTIONS,
60 - SILICON glua rectifiers, computer, axial leads
SO -GERMANIUM. glass rectifiers. signal, axial lead.

O:tl

$I91.15,,)

and hook -ups both.

x 31/2 o 31/2. Hookup spec sheets.

1.00 immense
1.00

-I

PHOTO TRANSISTOR, with darlington .me filter,

, with darlington amp. 255777, GE
PHOTO TRANSI
pancake, 3011 -70 ohms
PHOTO CELLS, Claire

1.00p

---

-Watt Stereo Amplifier,

-Track Tape Transport

'!

factory "snipped" most of the cables to this compact 8 watt stereo unit with aluminum escutcheon
plate. It's emy to use because we have all the cables
marked ready to use. With power supply. 116vac. 3
controls, LEFT and RIGHT VOLUME controls for two
speakers for balancing and center TONE control. With
knobs.

MV3, visible. "coax pin Pak ", red, mini dome lens
6- MV10B,_vieible, red, clear dome lens TO -18
1-) 6- MV10C, visible. red. diffused, dome lens, 1'0-18
0 '511A950, axial leads, micro -mini dome, clear. red, TO -18
green
lite
green
Iene,
micro
-mini,
axial
2.MV62,
yellow lite
9 2- MMV63, micro -mini, axial yellow
S -MV54, micro-mini, axial leads, red lens, red lite
0'5.MV55. micro-mini, axial leads, red lens, red lite ...
5- MVS012, red small dome lens, red lite, TO -18
.1A111V6013, em. dome, 2 hi red dome, soft ed Jiff. lite, TO-18
51.81V5020. iumbo clear dome, visible, red, rTO -18
e MV5054, red jumbo dome lens, TO -18 red lite, upright
51MV5090, TO -18, micro-mini red dome, red lite
O 5- MV60B0, TO -18, micro-mini flat clear lene, red lite
-MVSO04, red bi- polar, solid state letup V to 110- 115VAC -DC
341V5222, green jumbo dome, green lite, panel snap-in
2- MV5282, micro-mini, green lens TO -18, green lite
D 2- MV5322, yellow jumbo dome, yellow lite, panel snap -in
0 1- MV6491, jumbo, Tri- State, RED. GREEN, OFF. special
2 -MT2, photo transistor. light sensor. TO -18
MCT2, 1500V isolation photo transistor
COUPLERS D 2 MCb2,
1500V isolation photo diode

2
4

The

GIANT
SALE ON LED'S
LIGHT EMITTING DIODE GaAs INDICATORS

One of Poly Peke exclusive

fort 16.

equal to
MAN -1 or MAN -4 specs. Color - RED.
Green. tti yellow

wsEir raM6ut
SEMIKON

48 -HR. SERVICE

REFLECTIVE BAR TYPES

2.10
3 for $5.
SLA
.33
4.96
3 fer 313.
SLA
.70
3foe
SLA -I Is ,33}
2.50
SEA. 2,1

a complete 8 -track player system with

BUILT -IN PREAMP
just plug into any stereo amplifier (see some of our lowpriced unite). Excellent
replaceyement unit, or you can design your own
high system.
type
insert
cartridgetto turn -on
then enjoy p to 80
of non -atop, non -repeat etereo. Remove cartridgenutes
and
player 'shuts off" automatically. Built -in output controls in preamp. Features: 4 PROGRAM INDICATOR
LIGHTS. automatic or manual program
plays
your
vpchange.
ooled motor, which operaee off i i5Vac.1eRequires
external 12Vdc supply, for the electronics. With
diagrams.

2e -Years of

3 for SO.
3 for $3.
3

Same type unit found in the most expensive home

tape
players. It's

of Business
iTY

2e-Vean of MonyBach

(All "LED" TYPES)

$15.95

FOR HOME USE

2e-reen

MAN

PROFESSIONAL

TAPE TRANSPORT

SLA-1

MAN-

8 -TRACK

BLUE RIBBON

Each switch made

24V SPST mamas.
24V 1 amp contacte. K

eludes

'

white
decimal, white with
dot, and CE, CL.
functions blue wish

en,

in-

,ea

;cl,

4
-

characters.

ite

all

11nd80 cycles.
FILAMENT
Open
nen frame and metal en
TRANSFORMERS cased.
Output
8.3V

Sale
@

12.OVC1 O

3A OA
3A
2A

18.0VCT B
150.0V
SOMA
7.0V
(5
1A
Nixie tube transf.

Circle 106 on reader service card

www.americanradiohistory.com

51,00
2.95
2.95
2.60
2.95

Rated: net 30
Terms: dd postage
.3829
Phone Orders: Wakefield, Mus. (617
Retail, 16 -18 Del Carmine St., WakefielI lue.
(off Water Street) C.O.D.'S MAY BE P1 Lt.ED
20e CATALOG on Fiber Optics, 'ICs', S err: s, Parts
S4.00
MINIMUM ORDER

i'
I

POLY PAN:13

P.O.BOX-o42R,

IELD,MAS1

EB
.

1940

111

Quality
MINIATURE ALUMINUM
ELECTROLYTIC CAPACITORS

AXIAL LEAD
10

100

14c

12c

llc

14c

12c

l lc

UFD/50V
2.2 UFD/50V
3.3 UFD/35V
4.7 UFD/35V
10 UFD/16V.
10 UFD/25V.
22 UFD/16V.
22 UFD/25V.
33 UFD/16V
1

... 14c

12c

llc

14c

12c

l lc

14c

12c

11c

14c

12c

. . .

14c

12c

l lc
l lc

15c

13c

12c

.... 15c

33 UF0/25V.

UFD/16V..
47 UFD/25V..

11c

17c

13c

12c

..

17c

14c

13c

19c

15c

14c

47

12c

TYPE

...

100 UFD/16V
100 UFD/25V
220 UFD/16V
220 UFD/25V
330 UFD/16V
330 UFD/25V
470 UFD/16V

Io

loo

07V -3

19c

15c

14c

18c

17c

I';

1.185

TO-106

21

E142222.

10.106

.21

202712.

TD- 98
T0- 98
TO. 98

.18

.185
.160

165
.165
.145

24c

18c

17c

35c

25c

24c

35c

25c

24c

. .

44c

32c
27c

0750

35c

MV4

35c
55c

2 WATT
2 WATT

hi -pwr red

MV411

75c

35c
30c
39c
39c
60c

ME;

2 WATT

hi -pwr

75c

60c

55c

.
.

470 UFD/25V .
1000 UFD/16V
1000 UFD/25V
2200 UFD/16V

37c
49c

..

49c

..
..

12

.190
.190
.175
.175
.190

.175

.160

2N3391A
2N3393.

2113638.

10.106
10.105

2943640.

TO-106

.22
.20
.20
.21

2113643.

TO-105

.20

2143646.
2913906.

TO-106
T0. 92
TO- 92
TO. 92
T0- 92

T0.106
T0.106

.22
25
.27
.32
.27
.19
.19

.225
.240
290
.240
.170
170

T0-10

19

170

203563.

204126.
2N1403.

205089.
205133.
205137.
2145139.

E0930... T0.106

21

10.106

.21

E02907.. TO-106

.21

.175

2143392.. TO. 98

.12

.175

293394,.

.160

2913565..

51423698.

.160
.175
.175
.200

98

.22

T0.106
21436388. T0.105

.20

203641.. 14105
293645.. T0.105

.20

T00.

214390.
2944124..
2914401..
2945087..
2N5129..
.

.220

LED DISCRETE

M05021

260

.20
20
.25

T0- 92

27

.240

T0. 92
T0. 92

.32
.27
.19
.19

TO-10

205134.. T0.106
205138.. 10-106

150

2N3055

T00.

19

135

hi -pwr

091307

40

MINI -DIP Hi perf. AMPL

MINI -DIP Op AMP (super 741)

.185

051309K
LM311
/A320
107320
LM320
091380 14DIP 2 WATT Audio AMPL
057381
DIP Low noise Stereo Amp.

.290
.240
.170
.170
170

.220
150
.150
150

555
723
741

20

1.09

9602

5V

r , .: ,i
.

51.20
Dual D FF
1.20
Dual JO FF
1.30
4 bit Shift Register
2.30
EACH

7400

'

20.20

2.57

22.00
22.00
10

.50
.50
.90
1.75
1.00
1.90

1.90

1.85
1.70
1.75
.55
DIP Monostable Multivibrator
.65
DIP Dual 9601
1.20
8MIN7 -DIP TIMER
.90
DIP Precision Voltage Regulator
.45
SMI,NI -DIP Hi port'. Op Amplifier

HHN

7407

2.25
2.50

PAK

4.25
4.25
7.50
15.00
8.00
17.00
17.00
17.00
16.00
15.03
3.r '
9.
7.

''

7402
7403
7404
7405

HN

740E7

7408
7410

.22
.28
.28
.28
.22
.28
.40
.30
.28

.40
.45
.28

7411

7416
7420
7426
7430
7441
7445
7450
7460
7473
7474
7483

MPFIO2

10. 92

.380

.44

2115457..

.350

10. 92

.47

CT5001

.35

.22
1.25
1.10
.22
.22
.50
.50
1.00

.420

92

TO-

Min

&

1/2

DC

Curren, Gain of 5.000

IOmA.

01

.320

36

and divide:

.290

WAIT CARBON COMP.

1/4

$5.95

RESISTORS

Memory

each of the 85 standard 10% values (2.2 -22M) 'h W Resistors

(425 pcs.) Sorted by value 512 /set 2.4 are S11 /set 5-9 are $10 /set.

IC

FACH

74S206

of the 70 standard 10% values (10.5.6M) 1/4 W Resistors

(350 pcs.) Sorted by value S12 /set 2-4 are S11 /set 5-9 are S10 /set.

MIL -R -11 F xperiJi,wion rvpex.

vNw

10

.001....
.022

.047....
047....
.1

100

5c

3.5c

3c

6c
6c
9c
12c

4c
4c

3.5c
3.5c
5.3c
7.5c

6c
9c

VOLTAGE REGULATORS

L129

5V

1130

12V

L131

15V

600mA
500mA 17
450mA

567

10 /S 9.50

TON DKODER

Minidip

$29.95
..rK

^^*

565

DIP PLI

..,....

558 Minidip DUAL OP

53.57

808

10 /0 7.50

10/510.00

741

OP

AMP...

50c

10/5 4.50

10/510.50

748 Minidip OP

AMP...

60.

10/5 5.50

we
740111

14411
74041

32c
32c

.321
32,
.

35,

740514

281
28c
28c

7437N...51c

28C

747661

32c

46c
461
28c

31,

744191. 01 .45
744714. 1110

51.27
51.07

748311.
748641

7438/1

51c

71429

55,

741504 11.58 51.40

65,

7415411 52.25

12.00

91,
5158 01.40

7115%51.46

5119
11.01
51.39
51.39

51.22

741504 51.17
711539 1156
741581411.56
741604 51.95
74161N5195

72c

741624 1195

51.74

72c

74163N 11.95

7480N

60c
74,

74821. $102

..60c

55c

31c

744514.

01.61

1144

748944.

740611

52,

46c

74940

.52c

46,

74469. $1.30
7447N. 51.30

11.10

74079

SI.10

32c

744811. 51.35

745191.51.37
74921 .. 85,

36,

32c

74504

..

32,

SI 15
28c

32c
35c

28,
31,

745111

32c

28c

74940. 51.20 II 07
7495N. 51.20

56c

.32,
745491.. 321

28.

63c

44,

74511..32,

28c
28c

74994. 5120

50c

44,

740814

1409.
74104

7411/1

741311

741644

7417N

7453N.

..
..

32,

51.60

45c

51.39

74198N 52.78

72,

74151N 51.20

St 07

74199052.78

52.41
52.47

52,

454

74266

36c

321

74749.. 52,

743]0

32,

281

74750

28c
32c

35,

for

numbered,

house

(HN).

MCT26

6 PIN
10

MINI -DIP

FOR 510.00

95608

VISAS, -lib lAlf

RADIATION METER

VICTOREEN Model 710, brand new radiation

meter. Sensing element is hermetically sealed
ionization chamber. Uses 2 "D" cells, and 2
221/2 volt hearing aid batteries. 3 scales, reads
from .1 to 50 roentgens per hour. Designed by
government for CD units. Useful anywhere radiation is present. With manual and instructions.

11.01

COD ORDERS ACCEPTED FOR SAME DAY SHIPMENT

CALL 278- 681 -6674
Orders Less than $10.00 odd 50c Service Charge -Others Postpaid

Con/portents .Soli/

DIGI -KEY CORPORATION

112

53.00

HI- CURRENT TRANSFORMER

NEWSDEALER

Service Card

P.O. Boo 126

AT YOUR

for Free Catalog or Mail Readers

"Only (/ueliI,

4.511

11.07

74193951.80

7473N

Send

74140011.20
74181N53.38
74182011.17

7419%11.W 51.60

67,

BSc

50c

s1.74
741604 51.95 11.74
7416514 52.48 52.20
741604 52.03 51.80

99,
11.43

74604
74700
74729

51.07
51.07

55c

.>

ELECTRONICS

11.74
11.74

621

31c
28c

751

72c

60c

32,

7423N

36c
40c

85c

.70,

35c

7421

74107N
74121N

..

741221 72c
741231 51.11
74141051 e1
741501 5136

7418.

7493N

1450 54.00

.. 85c

are tested
function.
Some parts are

former, Variable Autotransformer, 2 bridge rectifiers, 2 high capacity electrolitic capacitors. (Meters and cabinet not supplied.)
Parts Kit
$22.50
2/$39.00
STOCK NO. J5166

RADIO -

DIGITAL TTL
.

parts are marked

and

4.50

We supply the following parts, to make a dual D.C. power supply

with the following ratings: 0 to 42 volts D.C. at 5.0 Amps., and
12 volts D.C. at 5.0 Amps. Switch, line cord, pilot light, trans-

10/530.00

AMP

747 Dip DUAL OP AMP51.10

740%

.111

1.811

DUAL VOLTAGE, HIGH CURRENT

VARIABLE POWER SUPPLY KIT

ISSUE OF

723 Dip VOLTAGE REG 51.15

Minidip

1.8"

These MAGNUS Model 1700 tone generator boards contain 12

separate oscillators, which produce a total of 37 notes. In addition, 3 additional oscillators are for chords, plus a power output
stage of about 5 watts. A great basic start for your electronic
organ. Boards are new, but as is, since some of the spring contacts may be bent, or a part broken. Board measures 271/2 "x41/2 ".
Value of parts alone worth many times our price. With data sheet.
2/$27.00
$14.94
Wt. 2 lbs.
STOCK NO. J5200

DECEMBER

10/530.00

$3.57

o-

Please ask for data

sheets as required.

PRICE

LINEAR INTEGRATED CIRCUITS

555 Minidip TIMER ... 51.00

IN

Solder 35c

24 Pin DIP Solder $1.25

(DIP)

DUAL
unless

WRITE TO:

V. common 9
pin tube base

8 Pin DIP

therwi se stated.

.t

..,gin

LOOK FOR

THE

14 Pin DIP Solder 45c

16 Pin DIP Solder 50c

LINE

2.017

10.03
9.00

IC',

MAGNUS TONE GENERATOR BOARD

1100 Calculator

IC SOCKETS
Frp

AlI

Circle 107 on reader service card

$5.00

74071

74074

flip

box AF Carmichael, Ca.

J''

litropilt

DISPLAY

74H51

74L00
74036

FIVE DOLLAR
MINIMUM ORDER.
FREE FIRST
CLASS POSTAGE ON ALL ORDERS. CALIFORNIA
RESIDENTS PLEASE ADD SALES TAX.

SENC STAMP FOR FREE FLYER.

,5

ea.

$ 1.80

IEE-APOLLO

FOR $49.00

5G5

25 V. DISC CAPS

74810

FLIP FLOP SPECIAL!

TTL RAM

74H04

low power RST

flop -DIP package
9
similar to SIGNET ICS 48424.
With data 6
application notes,
IO FOR 52.50

$Ix256EA 2001051 FOR $29 00

itap J -1.1. 3K

1.20 10.00
.50
4.50
1.35 12.00
1.40 12.00
2.50
.30
2.50
.30
2.50
.30
.30
2.50
.38
3.50
.38
3.50
.35
3.00
.75
6.00

3.0:7

Dual

ALL MERCHANDISE IS NEW UNUSED SURPLUS

AND IS SOLD ON A MONEY BACK GUARANTEE.

5 each

Resismrx ado available indiridunlls, in other assortments

or in boiex of 10101 prx. per tulk. 4 8 are hot molded

10

PAK

$10.00
10.00
11.00
20.00

2.511

CALCULATOR CHIP SPECIAL!

Forty -pin calculator chip will add, subtract, multi p'.

12 -digit display and calculate; chain
culatons; true credit balance sign output; autom:,l
overflow indication; fixed decimal point at 0, 2, 3,
.:
leading
z<rr,
suppression.

.375

7o

OPTO ISOLATOR SPECIAL!

MPS -A13.

1.80
2.50
2.50
2.50
1.80
2.50
3.50
2.60
2.50
3.50
3.80

51.25 EACH

NPN DARLINGTON TRANSISTOR

7492
74107
74153
74193
74800

10 PAK

MONSANTO

FIELD EFFECT TRANSISTORS

_1_6

Analog Switch

4016
04C74
74C76
74C195

CD

TL

I.

EACH

Regulator
T03 5V 10 Regulator
BDIP Hi perf. Volt. Comparator
T03 5V Negative Regulator
T03 12V Negative Regulator
T03 15V Negative Regulator

9001

'

17.

2.'.

,25

(STUD)

003096 Tl)5

.165
.175
.175
.160
.160
.160
.160

'

..

red
(hi -dome)
INFRA -RED

D
CMOS

0.

s .15

.165

.220
.260

DEVICES

axial micro-mini red

diffused dome red

LINEARS
05371

4ON
.185
.185
.185
.190
.190
.175
.175
.175
.175

T0. 92

.220
.750
.150

33

--

10

EACH

.115" 0 /5111 decimal (claw)

5 .90
.115" 0 /71711 decimal (flat leads) .80
.19" w /RH decimal (DIP)
2.00
.1" 5 r71'7its in One 12 pin DIP 2.50

M011-4

SILICON TRANSISTORS
50)18..

SEGMENT READOUTS

71V -3

24c

via AVr

,,,,.

Electronic Components

NOVEMBER 18

,4x

..

10 volts @ 10 A., 18 volts

Conservatively rated. Wt.

STOCK NO. J9906

Please include sufficient postage. Excess refunded. Send for new

revised catalog No. 12. Full of new items. MIN. ORDER $5.00

DELTA ELECTRONICS CO.

Phone (617) 388 -4705

Thief River Fails, MN 56701

Circle 102 on reader service card

A., 17 volts @ 6A.

lbs. 2 33/423/4x33/ax3
$8.95
2/$15.00

@ 6

Circle 101 on reader service card

www.americanradiohistory.com

PI

a,.edN..,

en S.IId Stab, PrinW Clreltry

Slide Rab Dial
All Peruse, All noun newel

Sala Order

Type
T

SN7400
SN7401
SN7402
SN7403
SN7404
5M7405

Features: 4- speaker system. built -in

FM antenna. record player Jacks on separate panel.
Another external panel consists of provisions for external FM and AM antenna. "satellite" speakers to
tape
provide 4- speaker ground, jacks for connecting

RCA TYPE
TRANSISTOR

ARRAYS

5.19

SN7409
SN7410

.19

$87411

.31

SN7412
SN7413

5147414

SN7415

$87416
SN7417
SN7420

SN7437
SN7438

.53
.89
25
.45
45

SN7440

SN7441
H SN7442
SN7443
SN7444
SN7445
SN7446
SN7447
5147445

SN7450
SN7451
SN7453
SN7454
SN7455
SN7480
SN7481
SN7462
SN7464
SN7465
SN7470
SN7471

SO
-22

$87421

.60
.29

SN7422

5017423
Cl

5147432

19
.27

.24
.79
.48
.27

32
35

587425

3147426
5147427

by type number' Spec sheers .,n request

537430

.1!

$87406
5717407
587408

corder te radio tuner or phono of systems to record.

Lower inputs for connecting tape deck that will play

back thru the internal amplifier for systems. AC jack for
phono power connection. RED. GREEN and CLEAR indicator. for Phono. AM. and FM respectively. Includes
red indicator on front panel for STEREO indicator.
Has separate input to plug into mike, guitar and other
musical instruments as well as another jack for plugheadphones.
ging in
pair of
Na controls on front panel. PHONO AM -FM. MONO. FM STEREO. GUITAR. TAPE.
ESCUTCHEON STEREOMIKE master control switch. LOUDNESS, BALANCE,
TREBLE, BASS controls, with power ON -OFF rocker
100 -watts
switch, end AFC ON-OFF. Designed for all audio -philes
arruslc power
to une ea wall unit in DEN or FAMILY ROOM, or control unit by easy chair in family room, or for those
AM-FM.
who wish to design their own console or modular sysMUE -DIAL
tem. With 6 ft. 115 VAC cord and plug. Only 13 x
7 x 31/2- deep. No escutcheon, but we include template
Indicator-al
for one, plus diagram. Shpt. wt. 8 lbs. With knobs.

AMPLIFIER

BUY 1001
TAKE 251%

FROM OUR 2 PAGE AD

Inflation-Fighting
,(
ECONOMY IPRICES;

60 -WATT STEREO
AMPLIFIER

AM-FMMULTIPLEX

BUY ANY 10 IC'S

TAKE 15%

Frst1
i Time.

rig!

.31

35

.24
.28

SN7472
SN7473

.45

$717474

.49

587476

1.00
1.00
1.10
1.10

.52
.79
.59
1.25

2.50
.49

2.95

SN7489
SN7490
SN7491
SN7492
SN7493
SN7494
SN7495
SN7488
SN74100
SN74104
SN74105
SN74106

.39

.28
.26
.26
.39

.39
.39

.49

.55

5374122

.49

1.81
1.38
.99

5N74148
SN74130
SN74151
SN74153
SN74154
SN74135
SN741S8
SN74157
SN74158
SN74160

.99

1.05
.99
.99
1.53

1.25
.95
.95

BL I1 1.58
SN7{1I3 1.73
SN71114 2.85
SN711'5 2.85
SIF7t1.6 1.85
SN711 1 1.85
s147:1 -I 2.23
SNT I
7 1.99
SN17

.95
.93

.95
.95 El
.49
.68
1.08
.88
.89 O
1.25

SN74123
SN74128
SN74126
SN74139
SN74140 2.50
SN74141 1.19
SN74145 1.19

.98
1.19

5147486

1.45
.27
.28
.28

SN74308
SN74112
SN74113
SN74114
5N74121

.91

SN7478
SN7480
SN7481
SN7482
SN7483
SN7485

Factory Marked

5574107

.52
.39

SN7475

.19
1.00
1.00
1.00

"ONLY"

.42

SNi.t

1.25
1.25

SNT-;7

SN7'It
SNT 1e01 3.95

SNa41112 1.05
SN771118 2.34

2.95
1.19
.99
1.39
1.89
1.29

2.34

SN7.e1117

SNA[1112 1.59

SN7at111 1.59
SN7ar11 t 1.89
S717'4191 1.10

SN1"4[61 1.20

1.45

SN1'4151

1.45
1.45

1.10

SN7'4;91 2.45
SN74191 2.45
SN7a26) 7.50

1.85

IC'S FOR EXPERIMENl'ERS

NATIONAL
Dic
(Al To
OP AMPS or min Dip
LINEAR
.i
.81
LM -300 POS V.R. (super 723) TO-6
.. .39
LM -301 Hi- performance op amp (A)

I;1.00

Money Back Guarantaal Factory MarkealI

SN7400.. 20 for $1.
8647490-

for 51.
5X7404.. 20 for $1.
8874107 1 for 51.
587413.. 5 for SI.
SN74122 l fer 91.
81
5717441.. 5 fer Si.'
LM -302 Voltage follower TO -5
89474122 1 for 51.
5X7442.. 8 for $1.
..1.15
LM -304 Neg. Volt. Reg. TO -S
5X741501
for $1.
537444.. 6 far $1.
95
LM -305 Pos. Voltage Reg. TO-5
57174154
for Si.
SN7445.. S for Ill.
39
LM -307 Super 741 op amp (A)
5X74181
for $1.
587446..
09
S
for
1
LM 308 HI -Q tat type op amp TO-S ...
$1.
5874189for S1.
3
5X7447..
106
LM -309H 5V Volt -Regulator TO -S
5 for
for Si,
587445.. S for, $1. CI 5X74192
LM -309K 5V Volt. -Rag. 1 Amp TO-3 ... 1 66
L-m874193
for $1.
125
LM -310 Voltage- Follower TO -5
587472, 10for$1.
874199
tier $1,
LM -311 Hi -Dorf. Volt. Comp. (A)
109
SN7473.. 10 for $l
fee
-good.
5717474..
LM -318 Prec. HI -Speed DIP
191
10 for
rejects IA daNts, who
$X7475.. S for 1.
1 50
LM -319 Hi -speed Dual Comp. DIP
knows at gnaw erleasl
$1.
I
I
i

$1.50

20-WATT STEREO AMP

Featuring solid state circuitry throughout. with printed
circuit ccnetruction, 10 watts "peak" audio power per
channel. Handsome walnut veneer grain with ,chrome
trim egcotcheon. With provisions for separate escutcheon mounting items as STEREO HEADPHONES. TREBLE.
BASS. BALANCE, VOLUME controls. separate PHONO
AND AUXILLIARY with separate OFF -ON POWER
switches. Chassis site 111/2 x 3 x 2 ". Separate rear
plate has right and left speaker phono type jacks. with
convenience power outlet for tape of phono and Auxilliary Inputs, for using amplifier with tape decks, and
other equipment. Separate external cables for stereo
phono connections. 6 -ft. power cord. separate ON -OFF
light indicator, and automatic turntable power plug,
with handsome -t of knobs. Wt. 2 lbs.

k.t
_.rf .ls.''a -16.95

choow any
3 for $3.

ii.

CA3026
CA3045
CA3054
CA3082

e''

LM -320
LM -322
LM -324
LM -339
LM -340

Money -Back
GUARANTEE
on all Items

60 -WATT STEREO
m -Lino' Type,PA
HIGH FIDELITY Wall ,.5Record
Meyer.
INFLATION
FIGHTING

AMPLIFIER

=3995

Milani Instruments!

The most amazing audio offer for the hi -fi -era. PA inmen,
the
and an ideal unit for the family den, or any room
eshouse, office. etc. Comes complete with hookup,
cutcheon, and knobs. 6 separate controls: LOUDNESS,
BALANCE, TREBLE, BASS, circuits switch for PHONO.
TUNER. TAPE, MIKE, AUX. 3 switches for SCRATCH
with
FILTER. RUMBLE FILTER, and POWER "ON -OFF"Sepawatts.
built -in lite. 4- output transistors. each4 30
speaker attachrate accessory mounting panel for
jack, tape. tuner,
ment, mike and' musical instrument116VAC,
60 cycles.
and power jacks. 6 -ft. cord set for
7 x 3 ". Wt. 3 Iba. With attractive
Measures only 13
multi -color escutcheon. Made by leading US maker.
4- Channel Sokr. Systems!
20- 20,000 Cycles Rasp

Pre,. Tinier
Quad (4 -741's In DIP)

Quad Comparator. DIP

Poe. V.R. TO3.1 -Amp 5. 6. 12.

15, 18, 24V

....
.....
........

AUDIO

POLY PARS

BLUE RIBBON

po1

Sanne

as

60

'er

t.

"

....559.95

t $59.95

2 for $19.95
em

reject, parts may belmissing..

D 555
556
558
560
561
562
565
54411

(2.50
.2.50
2.50

...

2.95
1.25
2.10
1.00
2.95
2.95

.2.95

_2.95
.2.95
.2.95

...
567 Tone decoder (A)
S702C Hi- grain. DC erne (70 -5)
704 TV sound IF system
711C Dual dun. comp (A)
Voltaire regulator (A)
110 723C

.......
....
741CV Freq. comp 709 (Mini DIP,
(A)
......
Freq.
741C
adi.
'748C
Block

iD

kIrXJI

LJ

753 Gain
739 -739 Dual stereo preanlp ..
741 -741 Dual 741C (TO- S)....
ULN2300M Op amp with SCR ..
CA3065 Video Audio sratam ..
RC4195 Dual I5V Tracking V.V.

.89
1.00
1.00

2.50
2.50
2.25

TVR -2000 Super 723,

RUT AMY 10
BUY ANY 100

AMOR

3 -WATT

JO -S

NEW LOWEST PRICES

B RAND

se.00

1.00

r DIP

(A) Ti)

.49
1.50
.33
.69
.44
.44
1.70

.1.98

..
..

41)6 Quad 741's (DIP) ...

..
RC 2556 Dust 555's

ELECTRIC

,lore

HI slew rate op -amp (TO -S)

Micro power 741 (TO -S)...
Micro power 709 (TO -S)
PET Input op amp (TO -S)
Timer 2 u Seconds to I -hr.
S Times fester than 741C.
..
Dual 741 (OIP)
Phase lock loops (DIP)
Phase lock loops (DIP)
Phase lock loops (DIP) ..
Phase lock loops IA)
function geaeretar (TO.n)

j'

-TAKE

157.
TAKE 25%

$2.50

At

Sale

538.88
xo 29 .95
Used extsaaively in hi -fi systems, tape decks. M tuners, record players, stereo componente, mini =a1 instruments, P.A., etc. All amplifiers, flat within 2 lb from
ha to 100,000. Each unit properly heat- iiok.3, with
heavy -duty connecting tie lug connection=.. Single ended puehpull output. Power supply requ:rrd l4VDC.
Output to 8 ohms.: Order by Stock No.
WITH DATA SHEETS
CLOCK CHIPS
$7.77
MM5311 6 -d1g1t 28-PM . .
ON A "DIPS'
7.77
MM6312 4 -digit 24 -Pin . .
7.77
,,.. I...o,
as
D MM5313 6 -digit 26 -Pln . .
7.77
-1n
6
-d1git
24
81145314
9.88
m
Aar
4
-digit
40
-Pin,
31313316
4.95
MM5316 -A no alarm

9rlIMSO

lOwiST

-..

48 -HR. SERVICE

.
.

MINI- COMPUTER PAR'rs

"MEMORY
LANE" Bey Any 3 _i Take

r] 1101

1103
2513
2516
0 7489
8223
8225
C]

With knob..

AM-FM-MULTIPLEX
GO-WATT
above ex,

amplifier heavy-duty

0 536

%Leer

T.TOM Ttar.

SANKEN HYBRID
p SI-110Y
6:
AUDIO POWER AMPS E:3,1::

ao - Yare
1MT[ORITY
k
MeweY-e
fe -Veers of
GUARAMT[[S
of [conam11
xo Yers PRIC[sl

FM
STEREO-AM-FM,
BASS
BALANCE. TREBLE.
Troll switch. LOUDNESS
rocker a Itch. Designed
controls, with power ON -OFF
d0- philes to use as wall unit
for all
unit by easy chairr In family
FAMILY ROOM, or control
to design their own conroom, or for those who wish
VAC cord and
modular system. With 6 ft. 116Snug. wt. 3 lbs.
sole
diagram.
x
31/2
x
7
13
plus
plug. Only

AM -FMMULTIPLEX

531
S32
533

Op Amps.

huera 3.6 watts continuous, 10 watts peak. With

xi /2x1/a "_ 9 to 30V SUP heat Fink., micro -mini sin:
PIy. High sensitivity. 8 to 16 ohms.
Mfge's Typo W
D

20 -watt Solid Suite Amplifier!

WITH GLASS
All Solid Stab, Printed Circuitry
ESCUTCHEON
Slide Rule Diei
All Purpose, All Fondly Sysbml
buy of 1974. A unit that
The most unusual HI -FI stereo
functions. makes it
different
and
has so many unique
the finest
in FM antenna. r ecord player
prices. Features: built-in
external panel
istr
jacke on separate panal. Another
speaker jacks.
of provision for "right" and "left"
connecting
external
record.
er to radio tuner or pItusa of
thru
deck that will play back
inputs for connecting tape
Includes red indicathe internal amplifier for systems.
Another jack
indicator.
STEREO
for
tor on front panel
for plugging in a pair of stereo headphones.
front
Has the following controls on
panel. Pmubr

e -eCTMY

and hookups.

STEREO

LINEAR

..2.6E

......

industrial lighting
A
that controls home. shopforand
any
cry elaborate circuit Easilycontrolling
speeds of electric
controls
devices.
0n
and electronic
rated
watts: brush
control
h 'variables speed x or23/edimming
x 2. With diagram
heavy -duty aluminum case. 8

20 -WATT

2.16
1.76

$3 995

.69
LM -350 Dual Peripheral Driver DIP -,
1.50
a LM -370 AGC Squelch op amp. TO-5
1 25
LM -371 R -F I -F op amp
3 S0
LM -373 AM -F%A SIB I.A.D, TO -5
3150
LM -374 AM FM SS IVAD TO-5
196
LM -376 Pos. V. Reg.
2.89
LM -377 Dual 2 -watt audio amp
1.69
LM -380 600mW LM -380, mini DIP
1.69
DIP
amp
pre
noise
dual
-381
Low
D LM
.
1.89
LM -382 Low noise dual pre amp DIP
59
LM -703 RF -IF amp, TO -S
.
51
O LM.703M RF -IF, op snap, min! DIP
.36
LM -709 Operational amplifier (A)
46
LM -710 Differential amplifier (A)
31
. . .
LM -711 Dual Differential Amp (A)
LM -723 Voltage Regulator (A)
69
LM -725 Instrument Op Amp
176
LM -733 Differential Video
41
LM -741 Freq. Comp. 709 (A)
41
LM -741CV Mini DIP 741C
6!
LM -747 Dual 741 (A)
41
LM -745 Freq. adWatabfs 741C (A)
ALI
Stereo pre amp 91P
Olt LM -1303
128
..
O LM1304 FM Stereo Multfolexer
.91
LM -1307 FM Multi. Stereo Dem. DIP .
LM-1458 Dual 741's mini DIP', TO.6 . .63
1.00
LM -1496 Modulator, Demodulator
1.50
it
step
Nr
f
LM -3028 Differential
.96
rror" amp
LM -3900 Quad "currant mirror"
2.50
LM 42500 Programable op amp
44
LM -75451 Dual peripheral driver
44
LM75453 Dual urleheel driver
C LM - 75491 Quad sag. driver. LED (DIP) ... 1 45
LM -75492 Hex digit driver, 250ma, DIP11 51

S4.95
SPEED CONTROL
INDUSTRIAL
(made for
$30 item from G.E, Model 533A

only

50
1.75

MINUS 5. 12 or 24V V.R. TO-3

107.

256 0(1 RAM MUS

..

52.50
6.95
10.50
1p. 50
6.50

1024 Bit RAM MOS ..

Character Gen. ROM
64 Bit RAM TIL
Programmable
'
ROM
64 bit read A write
RA 112.95
MM5260 1024 Bt
ROM 2.95
MM52822048 Bit RAM
8.50
'
RAM
MM5203 Er.
9.95
.. , . ' ' 37.50
.

8008 INTEL microprocesso

5302 Eraseable PROM
2500 BIT

111i,95

ty /.S0
11r

WttetB

Terms: add postage Rtedi set 30

Pho. Orders: Wakefield. Maas. I57

315 -3624

08

aer Street)

C.O.D.'S MAY

ED

20e CATALOG Fiber Optics, 'ICs' San .,Parts

$4.05
MINIMUM ORDFR

POLY PA 4S

P.0.80% 42R. LYNNFIELD,Mf Gt

IS

Circle 106 on reader service card

www.americanradiohistory.com

113

RADIO & TV tubes 36c each. One year guaranteed. Plus many unusual electronic bargains. Free catalog. CORNELL, 4217-E University, San Diego, CA 92105
CANADIAN'S free catalog. IC's Semi's, parts.
CORONET ELECTRONICS, 649A Notre Dame
W., Montreal, Que. Canada, H3C-1H8

design techniques.
Electronics
Monthly Newsletter. Digital, linear construction projects, design theory and procedures.
Sample copy $1.00. VALLEY WEST, Box
2119 -A, Sunnyvale, CA 94087
LEARN

INSTRUMENT

NEW

lo

IISf

WITH YOUR SCOPE

MULTITRACER

PRINTED CIRCUIT TECHNIQUES

0'
O
O O

boo

THE HOBBYIST
cutting -cleaningdrilling layout

FOR

O
O
O
O

SUSPENSION ETCHING

RUMBULL
BALRADR.,ELCERRITO,CA.

833

94530

,,.,u

y.41

O
O
O
O

,ti,IY
BOX 14.

MINIATURE TRIM POTS

5K, 10K, 25K, 50K, 100K

3/52.00

$.75 ea.

MULTI -TURN TRIM POTS

Similar to Bourns 3010 style
3,6" x

/'x114"
5

50, 100, 500, 2000, 5000,

10,000 ohms.
$1.50 ea.

3/$4.00

PRINTED CIRCUIT BOARD

6i,"

single sided fiber

glass board, Me" thick, unetched
$.40 ea.
5/$1.75
4%1" x

NIXIE TUBES

Similar to Raytheon 8650

tubes, with socket and data
sheet
$2.25
3/$6 00
TIS 73

N FET

$.50

2N4891 U1T

$.50

4/$1.00

ER900 TRIGGER DIODES

2N6027 PROG. U1T

$.75

VERIPAX PC BOARD
This board is a %;'single sided
paper epoxy board, 44 "x6 /,,"

(standard veripax), DRILLED and

ETCHED which will hold up to
21 single 14 pin IC's or 8, 16
or L51 DIP IC's with busses for
power supply connections. Is
also etched for.22 pin connector.
$5 25
FLV 100 VISIBLE LED
ME -4 IR LED
MCD -2 OPTO.1501
GREEN GAP OSL -16 LED
RED GAP OSL -3 LED
14 PIN DIP SOCKETS
16 PIN DIP SOCKETS

$.50
5.40
$.90
$.60
5.40
$.40
5.50

10 WATT ZENERS

3.9, 4.7

OR

5.75 EA.

OR 12 V

$.30 EA.

5.6

.4 WATT ZENERS

3.9, 5.6, 6.8

Silicon Power Rectifiers

PRV
lA
3A
12A
50A
100

.06

.11

200
400
600
800
1000

.07
.09

.16
.20
.25
.35
.45

.11

.15
.20

.30
.35
.50
.70
.90
1.10

.80
1.15
1.40
1.80
2.20
2.60

REGULATED MODULAR
POWER SUPPLIES
-15VDC AT 100 ma,
115VAC INPUT __
$19.95
5VDC AT 1A, 115VAC

INPUT
IN

._

4148 _

$19.95

14/$1.00

Terms:

FOB Cambridge, Mass. Send

or Money Order. Include
Postage. Minimum Order $3.00.

Check

CAPACITORS
6V 3OUF TANT
20V 4.7UF TANT

5/$1
5/$1
5/$1

1103 1024 bit RAM

NEC 6003 2048 bit RAM
1101 256 bit RAM
8225 64 bit -write RAM
8223 -PROGRAMMABLE

$4.75
$9.50
$1.75
$2.75

ROM

$4.75

Conductive

Elastometer low
profile calculator keyboard. A
23/4" X 31/4" X t/2" flex key
K +C

with off, on switch.

buttons
$6.00

TTL IC SERIES

7401740274037404740574067407740874107411741274137416741774207426742774307432743774387440-

.30
.18
.18
.18
.18
.22
.22
.37
.37
.24
.18
.30
.45
.75
.37
.37
.18
.30
.33
.18
.30
.44
.37
.21

7441 -1.05
7442 -1.00
7445 -1.10
7446 -1.15
7447 -1.15
7448 -1.20
7450- .18
7472- .40
7473- .43
7474- .49
7475- .75

74767480-

.47
.65
7483-1.10
7485 -1.30
7486- .48
7489 -2.75
7490- .75
7491 -1.30
7492- .75
7493- .75
7495- .99
7496- .95
8220 -1.50
74107- .50
74121- .60
74123 -1.00
74125 -1.40
74126 -1.40
74150 -1.15
74151- .95
74153 -1.10
74154 -1.65
74157 -1.25
74163 -1.60
74164 -2.05
74165 -2.05
74173 -1.80
74176 -1.80
74177 -1.80
74181 -3.60
74192 -1.50

74193 -1.45
74195 -1.00
75491 -1.10
Similar to 8038C IC Voltage
controlled oscillator, as featured in Oct. 73 P.E. they have
sine, square and triangular outputs good to IMHz. Two of
them can be used to make an

Ir

FM

generator

--

.60

10

157

$2.15
$3.50
$ .55
$ .65

165

CD 4001
CD 4002
CD 4009
CD 4010
CD 4011
CD 4012
CD 4013
CD 4016
CD 4022
CD 4023
CD 4025
CD 4027
CD 4030

5311

.80
.65
.55

$
$
$

.55
$1.20
$1.25
$2.25
$ .55
$ .55
$1.35
$

Fingertip Tuning
Barlow Wadley XCR -30
New concept in 9-volt battery
shortwave portable
featuring
0.5-30 MHz continuous tuning

with direct frequency readout.

.65

Totally

unlike other portables.

Full Wave Bridges

PRV

2A

25A

6A

200 .95 1.25

400 1.15 1.50
600 1.35 1.75
CLOCK CHIP 6 DIGIT

4.00
5.00
6.00

BCD
HOLD COUNT, OUTPUT STROBE $8.50
5314
CLOCK CHIP 6 DIGIT HOLD
COUNT, OUTPUT STROBE
$8.50
5316
ALARM CLOCK CHIP $12.50

2513

64x7x5

$11.50

CHARACTER GEN.
2516
64x6x8 STATIC
CHARACTER GEN.

19SK -6 keyboard having 0 -9,,

74L007400-

OROIR

(DIODE CLAMPED)
$ .55

02

Red or Yellow
LED READOUT ....$2.50
MAN -3 READOUT $1.75
MAN -4 READOUT $2.00
SLA 3
RED OR YELLOW $4.50

$11.50

SANKEN AUDIO POWER AMPS

Si 1010 Y 10 WATTS
Si 1025E 25 WATTS
Si 1050 E 50 WATTS

7.95
$18.88
$29.95
FPA- 711 -These Photo Diode Arrays
are used to read seven level tape
100 ma spacing
$5.95
S

LINEAR CIRCUITS

lA
+40V

LM 309K 5V

$1.65

723

.58
5 .35

REGULATOR
REGULATOR ..
301/748 -Hi Per. Op. Amp.
LM 320
or
V REG.
LM 376
to 37V POS REG.
741A or 741C OP. AMP.
709C OPER. AMP

-40

-5 -15
-V

$1.75
.58
.35
5 .29
5
5

560 -PHASE LOCK LOOP

$2.60

561 -PHASE LOCK LOOP

$2.60
565 -PHASE LOCK LOOP
52.60
52.95
567 -TONE DECODER
$ .55
703 -RF -IF AMP.
LM370 -AGC SQUELCH AMP.
$1.15
555
s
2 HR. TIMER
$ .98
5 .95
3822 -TRANSISTOR ARRAY
LM 380-2W AUDIO AMP
$1.45
LM 377 -2W Stereo Audio Amp $2.60
LM 381 -STEREO PREAMP
$1.75
LM 382-DUAL AUDIO PREAMP $1.75
LM 311
PER. COMPARATOR 5 .95
LM 319 -Dual Hi Speed Comp. $1.25
LM 339 -QUAD COMPARATOR .41.65
TRIACS
SCR'S
PRV lA l0A 25A
1.5A 6A 35A

-2

-HI

100 .40 .70

200 .70 1.10
400 1.10 1.60
600 1.70 2.30
No

1.30
1.75
2.60
3.00

P.

340T -5, 12, 15, 18, 24V

POS. REG. TO.220
$1.75
101 OPER. AMP. HI PERFORM
5 .75
LM 308 Oper. Amp., Low Power $1.05
747 -DUAL 741
$ .75
2.60
536 -FET INPUT OPER. AMP
$2.60
537- PRECISION OP. AMP.
LM 3900 -QUAD OP. AMP..... 5 .58
LM 324-QUAD 741
$2.20

$4.95
Send 20c for our catalog featuring Transistors and Rectifiers; 145

114

C /MOS

74C
74C
74C
74C

MAN -1

12V 10UF ELECT

50V 1000F ELECT
$.40
25V 30UF ELECT ....4/$1.00

-, X, =, =,

I'iy MORI'

tnocw,.pn

ELECTRONICS. SKOKIE. ILL. 60076

LESCO

TRANSISTOR SPECIALS
2N256 PNP GE TO-3
$ .50
2N404 PNP GE To -5
4/$1.00
2N11378 PNP GE TO-3
$ .95
2N1016A NPN Si TO -82
$1.95
2N2226 NPN Si TO-82
$2.50
MPS3393 NPN Si TO -92
4$1.00
2N3866 NPN Si TO -5
$ .75
2N2369 NPN Si TO -18
5 $1.00
2N3767 NPN Si TO -66
$ .70
2N2222 NPN Si T0 -18
5 $1.00
2N3055 NPN Si TO -3
$1.00
2N5296 NPN Si TO -220
$ .50
2N6109 PNP Si TO -220
$ .55
2N4898 PNP Si TO -66
$ .60
M12252 NPN Si TO -66 .............$ .90
2N3638 NPN Si TO -5
5 41.00
2N2218A NPN Si TO -5
4/$1.00

},

OR MONT Y

JAPANESE transistors, wholesale prices, free

catalog. WEST PACIFIC ELECTRONICS.
Box 25837, W. Los Angeles, CA 90025.
DIGITAL, Analog Electronics. Theory, design,
construction. Wide variety of topics. Lots of
circuit ideas. All projects tested. Send $1.00
for complete information and sample monthly
issue. SYNTEC CORP., P.O. BOX K, Bellingham, WA 98225

EXCEPTIONAL 5-acre ranch. Lake Conchas,

New Mexico. Only $995 per acre. Vacation
paradise. Good long -term investment. Easy
terms. Free brochure. RANCHOS, Box
2006RE, Alameda, CA 94501
TEKTRONIX 321A
Portable
All-Transistorized
3 ",
6MHz Triggered Scopes with 10:1
Probe
$495.00

$19.95

FLYBACK checker, scope adaptor. Easy to

operate. Removal from circuit not necessary.
$10.95 post paid. E.P. ELECTRONICS, 17 East
El Vado, Tucson, AZ 85706
DIGITAL electronics! Complete schematics,
parts lists, theories-Discrete Component
Digital Clock, $3.00. Increase technical competence, hobby skills -Complete course in
Digital Electronics is highly effective, $10.00.
Free literature. DYNASIGN, Box 6OR2, Wayland, MA 01778
AUTORANGING OMM, deluxe vom's, logic
probes and more. Lowest prices. Free catalog. ELECTRO INDUSTRIES, 4201 Irving
Park Road, Chicago, IL 60641
NEW Canadian Magazine, "Electronics Workshop", $5.00 yearly, sample $1.00. ETHCO,
Box 741 "A ", Montreal
SURPRISE! Build inexpensively, the most
unusual test instruments, futuristic gadgets
using numerical readouts! Catalogue free!
GBS, Box 100B, Greenbank, WV 24944
WHOLESALE, scanners, CB /SSB /AM, crystals, directories. Catalog 25c. G- ENTERPRISES, Box 461R, Clearfield, UT 84015.
SEMICONDUCTOR and parts catalog. J. & J.
ELECTRONICS, Box 1437, Winnipeg, Manitoba, Canada

.40 .50 1.20

.60 .70 1.60
1.00 .20 2.20
3.00

folk St., Cambridge, Mass

SOLID STATE SALES

RESISTORS -High stability, low noise carbon film. Free literature. STP, Box 146, Andover, NJ 07821
TROUBLE getting parts for projects? Let us
buy them for you. PARTS BUYING SERVICE,
Box 1026 -R2, Fremont, CA 94538
CALCULATOR owners: Use your +
calculator to compute square roots, cube
roots, trigonometric functions, logarithms,
exponentials, and more! Quickly, accurately,
easily! Send today for the Improved and
expanded edition of the first and best calculator manual -now in use throughout the
world
still only $2.00 postpaid with unconditional money -back guarantee! MALLMANN OPTICS AND ELECTRONICS, Dept. 7B, 836 South 113, West Allis, WI 53214
TWENTY disc, or 10 bar magnets, $1.00.
MAGNETS, Box 192 -E, Randallstown, Md.

-X

...

21133

BUILD your own 8k 16 bit computer for less

than $150 (less memory)! Parts and plans
available. Details $2.00. HAP, Box 21, Et-

trick, VA 23803

PARTS!
qt! Send

SOMERVILLE, MASS. 02143 TEL. (617) 547 -4005

www.americanradiohistory.com

New Items

Pgs

CORNEI

Gor 1;Pee

CORNELL'S
New Color
Catalog

4215

P.O. BOX 74D

GILFER ASSOCIATES, INC.

0. Box 239, Park Ridge, NJ 07656

ORDER FREE
IF NOT SNIPPED
IN 74 HOURS'

DIEGO CALIF. 92105

re

INTERNATIONAL ELECTRONICS UNLIMITEI

DIGITAL INTEGRATED CIRCUITS
Ea.

Ea.

7447

$1.15

7448

1.15

7450
7451
7453
7454
7460
7464
7465
7472
7473
7474
7475
7476
7483
7485
7486
7489
7490

.24
.27
.27
.39
.19
.39
.39
.36
.43
.43
.75
.47
1.11
1.39
.44
2.75
.76
1.29
.79
.79
.89
.89
.89
1.65
.49
.49
.57
.53
.99
.69
.79

74141 $1.23
74145 1.15
74150 1.09
74151
.89
74153
1.29
74154 1.59
74155 1.19
74156 1.29
74157 1.29
74161
1.39
74163 1.59
74164 1.89
74165 1.89
74166 1.65
74173 1.65

Ea.

7400

7401

7402
7403
7404
7405
7406
7407
7408
7409
7410
7411
7413
7415
7416
7417
7420
7422
7423
7425
7426
7427
7430
7432
7437
7438
7440
7441
7442
7443
7444

7445
7446

.19
.19
.19
.19
.22
.22
.39
.39
.25
.25
.19
.29
.79
.39
.39
.39
19
.29
.33

.39
.29
.35
.22
.29
.45

.39
.19
1.09
.99
.99

1.10
1.10
1.15

7491
7492
7493
7494
7495
7496

74100
74105
74107
74121
74122
74123
74125
74126

74176
74177
74180
74181

74182
74184
74185
74190
74191

74192
74193
74194
74195
74196
74197
74198
74199
74200

1.65

.99

1.09
3.65
.89
2.69
2.19
1.59
1.59
1.49
1.39
1.39

.33
.33
.33
.33
.33
.33
.33
.33

1.69

74151
74171

74172
74173

.49
.69

74L74

.69
.79

74155

74178
74185
74186

Internal 5V regulator
is complete with all necessary
components, case, probe, complete
instructions and logic chart.
$19.95

.33
.33
.33
.33
.33
.33
.33

TRANSISTOR GRAB BAG

Good for use

8092
8095
8121
8123
8130
8200
8210

.59
.59
1.39
.89

.99

2.19
2.19
7.95

5001

74190

1.69

74191

1.45

74193
74195
74198
741164
741165

1.69
1.69
2.79
2.79
2.79

(40 -Pin) Add, subtr., mult. & d v., 12 -dig.

Data supplied with chip
53.95 ea.
Data only
Refundable with purchase
1.00

1.59
2.19
2.59
3.49

.33
.33
.33
.33
.33
.33
.39

similar to 5001 exc. des. for battery

operated - Data supplied with chip
Refundable with purchase
Data only
751

9002
9301

.39
1.14

74H55
74H60
74H61
74H62
74H72
74H74
74H76

.39
.39
.39

8811
8812
8822
8830
8831
8836
8880

.69

.39
.49
.59
.59

2..19

1.10
2.59
2.59
2.59
.49
1.33

.79

.89
.89

Data only

MM5736 18 Pin,

74CO2

74C08
74C10
74C20
74C42
74C73

.75
.65
.65

2.15
1.55

74C74
74C76
74C107
74C151
74C154
74C157
74C160
74C161

Refundable with purchase

6 -dig.,

1.15
1.70
1.50
2.90
3.50
2.19
3.25
3.25

74C162
74C163
74C164
74C173
74C195
80C95
80C97

3.25
3.25
3.50
2.90
3.00
1.50
1.50

6 -dig. BCC

3.95 ea.

max
9.95 ea.

MM 5312 24 -pin any readout 4 digit 1pps output

BCD max with spec. sheet
6.95 ea.
MM 5313 28-pin any readout 6 digit Ipps
BCD max with spec. sheet
7.95 ea.

309K
310
311
319
320
324
339
3401

5/1.00
3/1.00
.60 ea.

DISPLAYS
'MAN1
MAN2

Red,

380 -8
381
382

MAN7
MANS
MAN66

1D1.707

7 seg., .270"
Yellow, 7 seg., .270"
75" high direct viewing LED
Red, 7 seg., .3"

Red,

ea.
ea.
ea.
ea.
ea.
ea.

1.39 ea.
3.95 ea.

4.65 m.
2.15 ea.

OPTO ISOLATOR5

MCD2
MCT2

Diodes
Transistor

3900
3905
7524

7525
7534
7535

8038
75451
75452
75453
75491
75492

Strip- detector
AM /FM /SSB Strip
Pos. Volt. Regulator
Watt Audio Amp
6W Audio amp
Low -Noise Dual Pre -Amp
Low -Noise Dual Pre -Amp
Prec. Voltage Regulator
Timer
RF -IF AMP
Operational AMPL
Dual Different. Compar.
Voltage Regulator
Dual Hi Perl. Op AMP
Comp. Op AMP
Dual 741 Op Amp
Freg. Adj. 741
Stereo Pre -Amp
FM Mulpx Stereo Demod
FM Mulpx Stereo 'Demod
Dual Comp. Op. Amp.
Dual LM 211 Volt. Comp.
2

TV-FM Sound System

FM Det: LMTR & Audio
Pm-Amp

TO -220
TO -5 or DIP
DIP

ea.

3S ea.

DIP
DIP

2_ ea.
1.49 ea.

ea.

MINI -DIP

1$ ea.

DIP
DIP
DIP

1_79 ea.
1_%3 ea.
_.,9 ea.

a
aa
3

MINI -DIP
ea.
MINI -DIP
16 ea.
TO -5 or DIP
ea.
DIP
ea.
DIP
ea.
DIP
113 ea.
MINI -DIP, TO-5 .. ea.
TO -5 or DIP
_,
ea.
MINI-DIP
9 ea.
DIP
DIP
DIP

1_w ea.

MINI -DIP
DIP

13

ea.

=1

ea.
ea.
ea.
ea.
ea.

DIP
DIP

._

Quad Amplifier
Precision Timer
Core Mem Sense AMPL
Core Mem Sense AMPL
Core Mem Sense Amp
Core Mem Sense Amp
Function Generator
Dual Peripheral Driver
Dual Peripheral Driver
(3511 Dual Periph. Driver
Quad. seg. driver for
LED readout

DIP
DIP
DIP
DIP
DIP
DIP
DIP

Hex digit driver

DIP

ea.
ea.
ea.
ea.
ea.
1.15 ea.

1__
_.

2a

--n ea.

MINI -DIP'
MINI -DIP
MINI -DIP

ea.
- ea.

DIP

ea.

._ ea.

der.
.00

TRANSISTOR SPECIAL

1.20 CD4023

,55

560

Phase Locked Loop

DIP

2.75 ea.

CD4009

.85 C134016

1.25 CD4025

.55

561

Phase Locked Loop

DIP

2.75 ea.

CD4010

.85 CD4017

2.95 CD4027

1.35

562

Phase Locked Loop

DIP

2.75 ea.

CD4011

.55' CD4019

1,35 CD4030

.95

565

Phase Locked Loop

DIP

2.65 ea.

CD4012

.55 CD4022

2.75 CD4035

2.85

566

Function Generator
Tone Generator

MINI DIP
MINI -DIP

2.75 ea.

567

Prime Qua I t
Hi Voltage Power Transistors
Typically 40 Beta at 50 MHz. 10W, 1A max 1;
NPN

400 VOLT

82.45 ea.

NPN

300 VOLT

1.20 ea.

NPN

200 VOLT

.75 ea.

1101

256 bit RAM MOS

1.75

1103

1024 bit RAM MOS

4.95

5260

1024 bit RAM Low Power

3.95
2.75
4.95

-5

With combinec
total of 100
trans

2.95 ea.

MEMORIES

bit RAM TTL

Programmable ROM

-,9

DIP MINI -DIP

I'

.69 ea.

.55 CD4013

64

1.a5 ea,
1.6 ea.

Please specify which data sheets are required with e

Add 5.50 per data sheet for items priced less than
each.

$1.09 ea.

CD4001

8223

ea.
ea.
ea.
ea.
ea.
ea.
ea.
ea.
ea.
ea.
ea.
ea.
1_35 ea.
1.6 ea.
1_3 ea.

PHASE LOCKED LOOPS

4000 SERIES RCA EQUIVALENT

7489

.'0

Volt. Reg.

2W Stereo amp

3075

seg., .270"

$2.50
Red alpha numeric, .32"
4.95
MAN3A Red, 7 seg., .127" in line leads
.79
MAN3M Red, 7 seg., .127" staggered leads 1.15
Red, 7 seg., .190"
MAN4
2.15
MANS
Green, 7 seg., .270"
2.95
7

Pos.

373
376
377
380

747
748
1303
1304
1307
1458
LH2111
3065

.25 ea.

TO -3
DIP
DIP

AF -IF

741

Visible red TO 18
Axial leads micromini dome .25 ea.
Jumbo clear dome visible red .35 ea.
Infra red (invisible) diff. dome

Neg. Reg. 5.2, 12, 15

Quad Op Amp
Quad Comparator

;72

739

MVIOB
MV50
MV5020

TO -5

MINI -DIP, TO -5 30
TO -5
Voltage Follower
.'9
Negative Voltage Regal. TO -5
-3
TO -5
15
Positive Voltage Regal.
MINI -DIP, TO-5 .35
Op AMP (super 741)
1J2
MINI -DIP
Micro Power Op Amp
113
TO -5
5 V Regulator 200 ma
1.r.5
TO -3
5 V IA Regulator
119
Voltage Follower Op AmpTO -5
MINI -DIP, TO -5 13
Hi pert. Volt. Compartr.
129
Hi -Speed Dual Compartr. DIP

(6V- 8V- 12V- 15V- 18V-24V)

AGC /Squelch AMPL

555
703
709
711
723

8.95 ea.

MM 5316 40 -pin norm. alarm set snooze alarm -timer

12 or 24 -hr. operat. with spec. sheet
12.95 ea.

Pos V Reg (super 723)

Hi performance AMP

370

550

MM 5314 24 -pin LED-Incandescent readout max

with spec. sheet

300
301
302
304
305
307
308

309H

1.00

add, subir., molt, div.

MM 5311 28 -pin any readout

with spat. sheet

ME4

.99
.89
Add

9601
9602

specify data sheets required with order.

1.50 Per data sheet for Items priced less than SIAO each.

.39
.55

1.00

5005 LSI (28 pin) Full 4 funct. mein. 12 -dig. displ. &
talc. 7 seg. mltplx. outp. Data suppl. w /chip 8.45 ea.

6 -digit

1.69
1.69
2.59
1.29
1.65
2.49

Please

74C00

7.95 ea.

DIGITAL CLOCK CHIPS

9000 SERIES TTL

9309
9312

CALCULATOR KIT

LINEAR INTEGRATED CIRCUITS

151

.69

74H22
74H30
74H40
74H50
74H52
74H53

8220
8230
8520
8551
8552
8554
8810

30/$1.00

1.25

74H21

8214

segment drivers

as

CALCULATOR CHIPS

.99

8000 SERIES TTL

8091

18 PIN

MM 5736 18 PIN Calc. Chip four function 6 Dig

A pair of 3-in-1 PAKS (6 digit) LED NSN 33
One 75492 HEX Digit driver
Schematic and instructions included. You supply
switches, keyboard and battery for complete calcule or.
53.95

PNP & NPN

Yield 50% + Good

HIGH SPEED TTL

74H00
74H01
74H04
74H08
74H10
74H11
74H20

Kit

5002

.33
.33
.33

POWER SUPPLY SPLITTER KIT

Ground reference for positive & negative
output from single supply any DC source to
Balanced output adjustment
1 amp-current capability with sink
increase usefulness of your power supply
Complete with all components & instructions

LOGIC PROBE KIT

Ten nano /sec capability
Checks TTL & DTL logic
Dual slope memory

1.85

LOW POWER TTL

74100
74102
74103
74104
74106
74L10
74L20
74L30
74142

10% OFF ON ORDERS OVER $25.00

15

All items are new, unused surplus parts-tested functional. Satisfac

post
is guaranteed. Shipment will be made via first class mail
paid
in U.S., Canada and Mexico within three days from receip
order. Minimum order
$5.00. California residents add sales to;

,408) 659 4773

INTERNATIONAL ELECTRONICS UNLIMITED

P.O. BOX 1708

Circle 103 on reader service card

www.americanradiohistory.com

MONTEREY, CALIF. 93940

USA

115

receive new weekly catalogue of

government surplus electronics bargains
plus "Buying Surplus." Just $6.00 /year.
INSIDE SCOOP, 5050 Roseville Rd. #B -34,
North H.ghlands, CA 95660

ADVERTISING INDEX

NOW,

ELECTRONIC ENGINEERING
& INSTRUCTION
TV tuner repairs -Complete course details,
12 repair tricks. Many plans. Two lessons, all
for $2. Refundable, FRANK BOCEK, Box 3236
(Enterprise), Redding, CA 96001.
SELF -STUDY CB radio repair course. There's
money to be made repairing CB radios. This
easy -to-learn course can prepare you for
a career in electronics enabling you to earn
as much as $16.00 an hour in your spare
time. For more information write: CB RADIO
REPAIR COURSE, Dept. 11 -R, 531 North
Ann Arbor, Oklahoma City, OK 73127
DEGREE program in Electronics Engineering.
Our 29th year! Free I,terature. COOK'S INSTITUTE, Dept. 14, Box 20345, Jackson, MS
39209.

BASEBALL collectibles. WALTERS, 622 Sunset, Muskegon, MI 49445

QUICK cash . . . for electronic equipment,
components, unused tubes. Send list now!
BARRY, 512 Broadway, New York, NY 10012,
212 Walker 5 -7000
CHIEF technician (German) 15 yrs. experience. Age 32 yrs., English speaking. Fully
qualified in color television, radio etc.,
maintenance, is very keen to obtain an interesting and preferably permanent post
starting January 1975. Please write to: GERT
WUENSCH, 28 Bremen 44, Bruchweg 19,
Germany.
DECEMBER 1974, Radio-Electronics presents the latest circuits and features to be
found in the 1975 lines of color TV sets. For
just one, there's an up -to-the -minute report
on the Magnavox digital keyboard remote
control.

COLUMBIA 4 CHANNEL SQ

Solid state SQ 4 channel adapter, 2

amps built in. Decodes 4 channel or
s nthesizes 4 channel. ....$35.00
r

'III

READER SERVICE
CARD NO.

For console installation,w /face

plate, no knobs.
Stereo amps for tape or turntable
$15.00
playback.
Pair of matching speakers w /wfmrs
$ 5.00
for above
HI I
'IBE
For use with most Instamatic
cameras. With nicad battery and
built -in charger. Never buy flash
$9.95
cubes again.
CALCULATOR CHASSIS

Fully assembled pocket calculator

chassis with calculator chip. Uses
LED readouts, not included .$5.00
POWER AMP XFMR 380 WATT
115 volt input, 64VCT 6 amp output.

$11.95 each, 2/$22, 5/$50

BOOKSHELF SPEAKERS

Completely finished, 9x12x5 inches. 16 ohm, with extension

$15 /pair
cord.
All above material plus shipping. 96
page catalog free.
JOHN MESHNA JR. PO Box 62
E. Lynn Mass. 01904

PAGE

Allison Automotive
107
29
Arrow Fastener Co., Inc.
84
Audio Amateur
67
88
Bell & Howell Schools
18 -21
15,22,23 B & K Division of
Dynascan Corp.
32, 78
96
Blonder-Tongue
Cover III
79
Brooks Radio & TV Corp.
99
91

BSR USA Ltd.

Castle TV Tuner
Service, Inc.
Channellock Inc.

70

WANTED

AM -F

RADIO -ELECTRONICS does not

assume responsibility for any
errors which may appear in the
index below.

97
25

89

Cover IV
80

Channel Master
17
21.
CIE, Cleveland Institute of
Electronics
74 -77
24
Continental Specialties Corp. .... 79
CREI, Division of the
McGraw -Hill Continuing
Education Center
56 -59
6
Crown International
14
18
Data Precision Corp.
71
5
Delta Products, Inc.
13
65
Edlie Electronics
87
93,95 Edmund Scientific Co.
107, 118
12
EICO,
Electronic Instrument, Inc..... 24
77
E & L Instruments Inc.
98
19
Electronics Book Service
72
EMC, Electronic
Measurement Corp.
102
85
Fluke
104
94
Fordham Radio Supply Co.
108
GC Electronics
101
83
Grantham School
of Electronics
103
GTE Sylvania
Electronic Components
2
92
Harwil Co.
107
100 Heath Co.
92 -97
88
Indiana Home Study Institute ....106
8
International Crystal
16
89
Tool
Jensen
& Alloy
106
2
Jerrold Electronics
1
27
Judson Research & Mfg. Co.
83
Kroch's & Brent. no's
83
13
Lafayette Radio Electronics
26
69
Leader
89
80
Lectrotech, Inc.
100
90
C. H. Mitchell Co.
Electronic Tool Division
107
82
MITS, Micro -Instrumentation
Telemetry Systems, Inc.
102
72
Mountain West
Alarm Supply Co.
90
71
National Camera Co.
90
National Technical Schools ....28 -31
NRI Training
8 -11
9

Circle 105 on reader service card

www.americanradiohistory.com

READER SERVICE
CARD NO.

PAGE

Non -Linear Systems, Inc.

100
Olson Radio Corp.
104
86
Oneida Electronics
Mfg. Co. Inc.
105
73
PAIA Electronics
90
28
Projector Recorder Belt Co.
83
1
PTS Electronics
Cover II
11
Radio Shack
23
RCA Electronic Components
Picture Tubes
25
17
Test Equipment
70
30
RGS Electronics
84
78
Rye Industries
98
61
Scelbi Computer
Consulting, Inc.
84
64
Schober Organ
86
26
Sencore Inc.
81
14,20 Shure Bros.
27, 73
62
Southwest Technical Products .... 85
4
Sprague Products Corp.
7
Supreme Publications
86
Sylvania Technical School
Home Study Division
38 -41
10
Tab Books
22
74
Technical Documentation
90
7,16 Tektronix, Inc.
15
66
Telematic
88
68
Tri -Star
88
63
Trigger Electronics
86
3
Tuner Service
5
Vintage Radio
106
75,76 Weller -Xcelite
Electronics Division
91
87
Winegard Co.
105
81

84

MARKET CENTER
98
99

101

102

Ancrona Corp.
ATV Research Corp.
Babylon Electronics
Cornell Electronics
Command Productions
Delta Electronics

117

Digi -Key
Gilfer Associates, Inc.

112

Gregory Electronics Corp.

GT Products
103 International Electronics
Unlimited
104 James Electronics
Lakeside Industries
Lesco Electronics
105 Meshna Electronics, John Jr.
Music Associated
Photolume Corp.
106 Polypaks
111,
Printed Circuits Techniques
for the Hobbyist
107

Solid State Sales

Valu-Pak

110
110
114

109
112

114
110
109
115

109
109

114
116
109
109
113

114

114
112

CMOS
4000AE
4001AE
4002A E
4004AE
4006AE
4007 A E
4008AE
4009AE
4010AE
4011AE
4012AE
4013AE
4014A E
4015AE
4016A
4017AE
4018AE
4019A
4020AE
4021AE
4022AE
4023A E
4024AE
4025AE
4026A E
4027AE
4028AE
4029AE
4030AE
4035A E
4037AE
4040AE
4041AE
4042AE
4043AE
4044AE
4048AE
4049AE
4050AE
4051AE
4056AE
4060AE
4069AE
4076A E

.65

3.60
.95
1.20
.55
.55

1.40
3.80
3.80
1.15
2.95
3.20
1.30
4.20
3.80
2.95
.55
2.30
.55

9.90

1.85
2.95
5.40
1.25
1.80
4.00
4.70
3.35
2.95
2.95
2.95
1.50
1.35
1.35
5.40
3.50
4.95
.90
4.30

Audio Amps
LM352: 6-15V, 1.15W, 8S2
LM354A: 6-27V, 2.80W, 812
TAA611 B12: 6-15V, 1.15W, 8S2
TAA621Al2: 6-27V, 1.40W, 82
TBA641811: 6-18V, 2.20W, 412
TBA800: 5-30V, 4.70W, 80
TBA810AS: 4-20V, 2.50W 4S2
TBA820: 3-16V, 0.75W, 452
TCA830: 5-20V, 2.00W, 42
TCA940: 6-24V, 6.50W, 812

HIGH

SPEED TTL
.34
.49
.36
.38

.44
.44
.44
.38
.39
.36
.69

1.60

2.50
1.60
2.00
3.00
2.20
3.00
1.70
2.20

4.40

DUAL LOW
NOISE
OP AMP
LM331N:
V io = 6mV
11e=

100onA

lb = 2000nA
Noise= 1.5dB
$2.20

Stereo
Demodulator
FM

XR1310

$3.90

HYBRID

,r

POWE1MPLIFIERS

Power
SI
SI
SI

-/,

/,

.125 "diz .

-1010Y
-1025E
-1050E

RMS
10W
25W
50W

IHF
25W
65W
120W

Price
$

6.40
18.00
25.40

Digital
ch
with liquid crystal display.
Beautiful, reliable & accurate. $149.00 plus $2.50
for shipping & handling.

/IeI

I It./1

,e-- ,,,,sr
V u. f000$ I

741 ON

7411N
.51
7412N
7413N
.79
7414N
2.81
.47
7416N
7417N
.64
7420N
.25
7421N
.51
7423N
.49
.49
7425N
.49
7426N
7427N
.54
7428N
.51
7430N
.23
7432N
.29
.61
7433N
.49
7437N
.49
7438N
1.01
7439N
.23
7440N
7441AN 1.16
.99
7442N
1.14
7445N
7447N
1.39
7448N
1.29
7450N
.23
7451N
.29
7453N
.26
7454N
.26
7460N
.24
7470N
.31
7472N
.39
7473N
.47
7474N
.47

74150N
74151N
74152N
74153N
74154N
74155N
74156N
74157N
74158N
74160N
74161N
74162N
74163N
74164N
74165N
74166N
74170N
74173N
74174N
74175N
74176N
74177N
74180N
74181N
74182N
74184N
74185N
74190N
74191N
74192N
74193N
74194N
74195N
74196N
74197N
74198N
74199N
74200N
74221N
74251N
74278N
74279 N
74293N
74298N

1.14
.89

2.25
1.12
1.64
1.49
1.49
1.26
1.54
1.89
1.59
2.05
1.59
1.89
1.89
1.98
2.55
1.79
1.52
1.92
1.69
1.69
2.49
3.85
1.19
2.89
2.29
2.89
2.89
1.49
1.39
1.89
.99
2.39
2.39
2.59
4.48
5.05
1.75
1.75
2.95
.92
.92
2.55

LOW
POWER TTL
74L00N
74L02N
74L03N
74L04N
74L1ON
74L20N
74L42N
74L47N
74L51N
74L73N
74L74N
74L90N
74L93N
74L95N
93L00
93L01
93L08
93L09
93L10
93L11
93L12
93L14
93L16
93L18
93L21
93L22
93L24
93L28
93L34
93L38
93L40
93L41
93L60
93L66

.34
.34
.39
.39
.34
.39
1.62
1.62
.34
.74
.89
1.62
1.74
1.62
1.50
1.60
3.40
1.80
2.80
4.20
1.80
1.70
3.20
3.50
1.50
1.80
2.80
3.70
4.00
4.20
6.50
6.50
3.00
2.70

MIN. ORDER
$10.00

COMP1<7TER
INTERI-YLICE

DM8820N
DM8820AN
DM8830N
DM8831N
DM8832N
9600
9601

4.00
6.50
4.50
5.00
5.00
1.30
1.30

.200adia.

9602
9614
9615
9616
9617
9620
9621

25
30
30

Red

Yellow
Green

SLA1
SLA11
SLA21
SLA2
SLA12
SLA22

Red

2.25

G reed

4.25

4.25
1 Rer.
2.25
1 Greer 2.25

SLA3
SLA4

2.25
7.50
7.50

Rea
Red

0ptolsoll ad or
1.45

MCT2

LM301 A
LM301 AM

--

.79
7475N
.59
7476N
.66
7480N
1.21
7481N
1.01
7482N
1.01
7483N
7484N
3.01
7485N
2.49
7486N
.49
7489N
2.99
7490N
.79
7491N
1.29
7492N
.84
7493N
.84
7493AN
.86
7494N
1.29
7495N
.99
7495AN 1.51
7496N
1.09
7497N
1.51
74100N 1.65
74105N
.54
74107N
.49
74108N
.91
74109N
.91
74110N
.71
74111N
.91
74114N
.91
74115N
.91
74118N
.91
74119N
.81
.59
74121N
74122N
.89
74123N
.96
74125N 1.39
74126N 1.39
74128N 1.21
74132N 2.05
74136N
.91
74141N 1.89
74145N 1.79
74147N 2.95
74148N 3.55

30

Linear I4 3

$7.50

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,e,",

7400M TTL

.25
30

Yellow

Display s

Decoded Read/
Write RAM
P1103

Red

Green

220
220
220

ea

$7.00
8.50
8.50
16.00
P2102
5.50
P3101
5.50
P3101A
5.00
MM6560N
5.00
MM6561 N
5.00
DM8599N
5.00
93403
P1101A
P1101A1
P1402A

.18
.27
.23
.23
.25
.29
.42
.49
.24
.54
.24
.29

35
35

Green

160 "dial.

Now you can take advantage of our component buying skills and power. Select
broad range of advanced devices. Enjoy competitive and often amazingly low
prices. Depend on shipment in 48 hours or less and rely on our guarantee of complete
ANCRONA CORPORATION.
satisfaction

7400N
7401N
7402N
7403N
7404N
7405N
7406N
7407N
7408N
7409N

25

-.

Yellow

216
216
216

PREMIUM QUALITY COMPONENTS

from

Red

209
209
209

LM100H $5.50
LM104H
6.50
LM105H
5.10
LM105F
8.50
LM109H
9.50
LM109K
6.30
LM200H
3.80
LM204H
4.70
LM205H
3.00
LM209H
3.50
LM209K
3.70
.90
LM300H
LM300N
1.40
LM304H
1.40
LM305H
1.10
LM305AH
1.40
1.20
LM305N
1.75
LM309H
1.95
LM309K
LM335
2.30
LM336
2.40
LM337
2.40
LM340-05K 2.60
LM340-06K 2.60
LM340-08K 2.60
LM340-12K 2.60
LM340-15K 2.60
LM340-18K 2.60
LM340-24K 2.60
LM723H
1.30
LM723D
3.90
LM723CH
.80
.75
LM723CN
1.50
L129
1.50
L130
L131
1.50

When you order from us, that is what you receive! We've been buying and
selling top quality components for nearly ten years. Our annual volume exceeds $3
million. We handle only original parts, from the world's leading manufacturers and
our customers include some of the largest and most quality-conscious companies.

$ .80

.80
SN74S02N
SN74S03N
.80
SN74SO4N
.80
.80
SN74S08N
.80
SN74S1ON
.80
SN74S11N
.80
SN74S2oN
.80
SN74S3oN
.80
SN74S32N
.80
SN74S4ON
.80
SN74S41N
.80
SN74S64N
1.30
SN74S74N
6.10
SN74S85N
2.90
SN74S86N
SN74S112N 2.50
SN74S113N 1.50
SN74S133N 1.00
SN74S138N 4.50
SN74S139N 4.20
SN74S14oN 1.00
SN74S151N 3.30
SN74S153N 3.30
SN74S154N 3.40
SN74S157N 3.00
SN74S158N 3.00
SN74S160N 6.60
SN74S161N 6.60
SN74S174N 4.75
SN74S175N 5.00
SN74S181N 12.50
SN74S189N 5.10
SN74S194N 4.40
SN74S195N 4.40
SN74S251N 4.20
SN74S253N 4.20
SN74S275N 3.20
SN74S258N 3.70
.90
SN74S260N
SN74S280N 5.70
SN74S289N 5.00
6.80
93S10
6.80
93516
3.50
93S21
3.20
93S22
3.70
93S48

74H40N
74H74N

a highly versatile lab

instrument at a fraction of
the cost of conventional unit.
Kit includes two XR205 IC's,
data & applications, PC board
(etched & drilled, ready for
assembly) and detailed instructions.

LEDit;

Voltage

Here's

5.90
3.90

SN74SOON

74H2ON

XR205K Only $28.00

.55
.55
.60

Schottky

74H00N
74H01N
74H04N
74H05N
74H08N
74H10N
74H11N
74H15N

warewrmceneratorKit

2.00
3.00
3.00
4.50
3.00
3.50
3.00

LM301AN
LM302H
LM 302 N

LM306H
LM307 H
LM307M
LM3o8H
LM308AH
LM310H
LM311 H
LM318H
LM555CM
LM709CH
LM 709CN
LM71oCH
LM710CN
LM725CH
LM733CH
LM733CN
LM741CH
LM741 CM
LM747CH
LM747CN
LM748CN
LM 3046CN
L M 3054C N

$.90

TO -E

Minidis,

.75

Dip
TO -S
Dip
TO-E

1.10
.95
1.40
2.80
TO -E
.90
Mini dip .90
1.20
TO-5
5.00
TO -5
TO e,
1.40
TO -E
1.70
TO-5
2.50
Minidia .95
TO -5
.45
.45
Dip
TO -5
.60
Dip
.75
5.00
TO -E
1.50
TO-E.
1.50
Dip
TO -5
.45
Minidia .44
1.90
TO -f
Dip
.90
Dip
.40
.95
Dip
1.50
Dip

Phase Locked L3ops

LM567CM Minidia 2.00

PULSE GENERATOR

IC soclal -ts
Interdesign 1101: 0.1Hz -2MHz,
0-5V Output, var. width, line or
battery operation. $159.00.

Power Regulators
LM335K: 5V, 600mA
LM336K: 12V, 500mA
LM337K: 15V, 450mA

2.40
3.50
3.60

Power Transistors
BU204
B205
BU206
B207
B208
B209

1300V
1500V
1700V
1300V
1500V
1700V

4.14
4.95
5.94
5.85
6.93
8.64

DATA PACKETS
$.50
for all products
literature
Contains
TECHNICAL

SALES TAX: California residents add 6 %; Canadian

esidents add 12% federal sales tax, and add 5% in B.C.

SEND CHECK OR MONEY ORDER (NO. C.O.D.) TO:

ANCRONA

P. O. Box 2208R, Culver City, CA. 90230

8 pin DIL
14 pin DIL
16 pin DIL

24 pin
28 pin
36 pin
40 pin

DIL
DIL
DIL
DIL

2
6

-9
.75
1.10
1.70
1.30

Teflon.
3 pin
4 pin
6 pin
8

pin

10 pin

TO -5
TO-5
TO -5
TO -5
TO -5

55
65

90
10

40

Shift Reg il; Cers

1402A
1403A
1404A
1405A
1406
1407
1506
1507
2505K
2512K
2524V
2525V
2807
2808
TMS3114
MM5055N
MM5056H
MM5057N

1
`

4.2
5._

4.0
5

4.D
5.5
8-2

5.0
5.0

5.0

117
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Easy to build low -cost kit needs no

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has 3 bands of audio frequencies to
modulate 3 independent strings of
colored lamps (i.e. "lows" -reds, "middles"- greens, "highs " -blues. Just connect hi -fi, radio, power lamp etc. &
plug ea. lamp string into own channel (max. 300w ea.) Kit features 3 neon indicators, color intensity controls controlled
individ SCR circuits; isolation transformer; custom
plastic
housing; instructions.

New, great buy for Infra -red crime

detection surveillance, security system alignment, I. R. detection, laser
checking, nite wildlife study, any
work requiring I. R. detection and

conversion to visible spectrum. Self

contained scope w/ everything but I.R. light source works in
any I.R. lit area 6V or 12V power, 6032 I.R. converter tube, f/4.5
objective lens, adjustable triplet eyepiece, shockproof housing.
See bright in dark! Under 4 lb., comparable to others at $350
& up.

$18.95 Ppd.

Stock No. 41,831 EH

IN SECONDS

Edmund's new electronic oral thermometer obsoletes glass mercury

type. Seconds instead of minutes,
more accurate, much easier to read!
Put disposable cover (supply incl.) on
flexible probe, place under tongue,
push button, dial meter center, read
temp fast in F. & C. . 92- 106 F.
133- 41 C.) in I/ increments, 97- 101 F. to I/t Safe, hygienic,
no squinting. Compact metal case fits in doctors', nurses' shirt
pocket. Inds. 9V trans, batt., instrs.
Stock No. 42,210 EH
$25.00 Ppd.

And our FREE 164 PAGE CATALOG is packed

with exciting and unusual values in ecological and
physical science items
plus 4,500 finds for fun,
study or profit... for every member of the family.

$199.95 Ppd.

No. 1648 EH (11x141/4x3 ")

PRO ELECTRONIC
SOUND CATCHER

KNOW YOUR ALPHA FROM THETA!

Parabolic mike w/ 183/4" reflecting

shield & 2 I.C.'s in amplifier magnifies signals 100X that of omni- directional mikes. Catch a songbird 1/2
mile off; QB's huddle strategy; sounds
never before heard. Super directivity
gives highest signal to noise ratio poss. Safe: auto. cuts off
ear damaging noises. Earphones, tape recorder output, tripod
socket. Req. two 9v trans. batt. (not incl).
No. 1649 EH (51/2 LB.)
$299.00 Ppd.
BIG EAR "TOY" MODEL -80,176 EH
$32.25 Ppd.

waves. Ultra- sensitive electrode headband slips on /off in seconds- eliminates need for messy creams, etc.

For greater relaxation, concentration,

listen to your Alpha -Theta brain -

Atch'd to amplifier, filters brain waves, signals beep for ea. Alpha
or Theta wave passed. Monitoring

button simulates Alpha sound; audio & visual (L.E.D.) feedback.

Reliable, easy -to -use unit -comparable to costlier models. Corn pletely safe. Comprehensive instruction booklet.
No. 1635 EH (8x3x4 "; 24 oz.)

SE

LIE DETECTOR TYPE METER

$134.50 Ppd.

LOW COST "STARTER" UNIT

No. 71,809 EH

$55.00 Ppd.

NEW! KIRLIAN PHOTOGRAPHY KIT!

Experiment in the fascinating new

Amazing Emotion Meter reveals hidATEa

den likes, dislikes. Easy to use; senTELLING
sitive, accurate. Measures changes in
THE Tlrrge
body resistance caused by changes
YOp
in emotional state. Needle movement
E,LLY
indicates emotional response (not
whether favorable or unfavorable).
Effectiveness depends on questions asked and interpretation.
Unique 10 -oz. set ideal for entertainment and education
parties, science projects, psychological experiments. Requires 9V
transistor battery (not included). Instructions.
No. 42,194 EH (27/Bx4x13/4 ")
$19.95 Ppd.

field of "Kirlian electrophotography"

-images obtained on film without
camera or lens by direct recording of
electric charge transmitted by animate & inanimate objects. Each
"aura" differs- animate aura said to
change corresponding to physical
changes. Kit inclo portable darkroom, double transformer isolated from power source; instructions.

No. 71,938 EH ...

"HIGH VOLTAGE PHOTOGRAPHY" by H. S. Dakin
No. 9129 EH (60 -PG.) PPBK BK.)

$49.95 Ppd.
$5.00 Ppd.

3" ASTRONOMICAL
REFLECTING TELESCOPE
See stars, moon, planets close-up! 30
to 90X. Famous Mt. Palomar Type.
Aluminized & overcoated 3" diameter

GET A CHARGE
FROM THE SUN!

Our 12V Solar Battery Charger allows

direct conversion of light -to- electricity.
Compact panel put on a boat can
automatically charge its 12V battery
over entire daylite period. Use anywhere for a trickle charge. Big value,
it comprises 3012V silicon solar cells in series w diode.
No. 71,971 EH (AB. 30 W- MRS. /WK.)
$89.95 Ppd.
9x18" HI CURRENT MODEL (6W, 12V, 500 mA)
No. 72,010 EH (AB. 150 W- HRS. /WK.)
$420.00 Ppd
6x6" LO VOLTAGE MODEL (1.5V, .38W, 250 mA)
No. 42,172 EH
$49.95 Ppd.

f /10 primary mirror, ventilated cell.

Fork type equatorial mount. Durable
PVC tube. Includes 1" F.L. 30X Rams den, Barlow lens to triple power, 3X
finder telescopes, hardwood tripod.
FREE "STAR CHART", "HOW TO USE" book.
No. 85,240 EH
$49.95 Ppd.
DELUXE 3" REFLECTOR TELESCOPE #80,162 EH
$79.95 Ppd.
41/4" REFLECTOR (45X to 135X)
#85,105 EH ....$149.50 FOB
6" REFLECTOR (48X to 360X)
#85,187 EH ....$249.50 FOB

MAIL COUPON FOR

GIANT FREE
CATALOG!
164 PAGES

MORE THAN

4500 BARGAINS

(n

Completely new Catalog Packed wttn huge selection of telescopes. m

ctoscopes. binoculars magnets. magnilte,s, pr,Sms. photo components.
cology and Untoue lighting items. parts, kits. accessories
many
hard-to-get surplus bargains 100's of charts. ,llustrat,ons For hobbyists. erper,menters. schools industry

EDMUND SCIENTIFIC CO.

300 gdscarp Budding,

CC

Barrington,

PI. 1.

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118

Total

30 DAY
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Think of him as a 250 Ib.antenna.

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But when the winds get ro ugh,
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These exclusive features riake
it all possible:
Highest starting and rune rig
torque (175 to 200 inch lbs.
-- motor uses filtered DC pc ver
supply.
Accurate 2- degree resetting
-push -to -start silent contro
unique direction sensing circuit
utilizing five wire control cable:
differential servo sensing aiiplifier with solid -state switc ii -g:
hermetically- sealed powe relay
automatically disconnects r _rtor
when not in use
Reliability -weatherproof
terminals use foam -filled lx- d:
long -life, self -lubricated Celcon
gears: bronze worm gear aid
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it

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SOlDER.
Ti'
Instruments for
Service

signa/ circuit analyzing.

When Castle introduced the TV

Tuner SUBBER *analyzing instrument

a couple of years ago it became the first
practical way to easily test the VHF
tuner, UHF tuner and i.f. amplifier
system of any TV receiver. Being
lightweight, self contained and battery
powered the TV Tuner SUBBER *Mk.
IV is the first such instrument which
may be carried on service calls and used
with ANY color or black and white TV
receiver
at $45.95 for the battery
powered Mk. IV, or $54.95 for the a.c.
plus battery powered Mk. IV -A the
instruments have been known to pay for
themselves in TIMESAVING in the
first two weeks of use!
Now we have introduced the Mk. V
Master SUBBER*, an instrument
which is absolutely unique
there is
nothing else like it anywhere! It is

...

...

completely

portable

and battery

powered, practically foolproof in it's

simplicity of operation when testing
ALL the signal stages of any color or
black and white TV receiver. The
substitution signals available allow tests
of the following stages: VHF tuner,
UHF tuner, each video i.f. amplifier,
video detectors, video amplifiers, 4.5
MHz sound i.f. amplifiers, sound
limiter, sound detector and audio
amplifier. It includes a signal level meter
for testing the antenna signal. Inbuilt
telescopic antenna makes the meter
adaptable for true field strength

measurements.

Inbuilt

monitor

loudspeaker ensures foolproof substitution tests

every time!
At $169.95 the Master SUBBER* instrument is the best bargain in
an analyzer that has ever been available.
It will save oodles of time in the hands of
a professional troubleshooter
and
help advance the novice to professional
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All SUBBER" instruments come
complete with batteries, connecting
cables and comprehensive instruction
manual. The Master SUBBER" and Mk.
IV -A TV Tuner SUBBER* come
complete with wall plug -in transformer
for 120vac 60 Hz operation.
As an added bonus, all SUBBER *instruments enable use of the high
speed agc system analyzing procedure
invented by Castle
the first practical
method for analyzing agc system defects
without confusion.

...

...

...

*A trademark of Castle TV Tuner Service, Inc.

These instruments boast the extra features of all

Castle products
advanced technology
modern
styling
and they work!

If you need to save some analyzing time

need a SUBBER* instrument!

you

your stocking distributor ... or write for more

details and complete specifications.
See

CASTLE TV TUNER SERVICE, INC.

5715 N.

Western Ave., Chicago, Illinois 60645

In Canada: Len

Circle 97 on reader service card

www.americanradiohistory.com

Phone: (312) 561 -6354

Finkler Ltd., Ontario