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Technology &. The Solar Challenge Racers
SERVICING -VINTAGE RADIO - COMPUTERS -AMATEUR RADIO - PROJECTS TO BUILD
A-3000 REMOTE CONTROL UNIT MODEL 1133 REMOTE ACCESS
TELEPHONE/ ANSWERING
MACHINE
You can control just about anything with this Remote Control
Transmitter/Receiver. Eg. TV:S, Stereo's, Alarm:S etc.
* N.0./N.C. relay output up to 5 amps.
* Receiver operating voltage: 12V DC.
* Complete with two remote keys.
Telephone Features:
Tone/Pulse switchable.
Last number redial.
Ringer on/ off switch.
Lighted dialing keypad.
* Operating distance: 10 meters.
was$109.95
now $89.95
KASPAROV POCKET PLUS
CHESS COMPUTER
Answering Machine
Features:
Single micro cassette.
VOX recording.
Call screening.
Toll saver function.
Tone. remote control
to access messages
from touch tone phones.
TELECOM APPROVED
* 8 levels of skill to Advanced from
Beginner to Intermediate.
* You set the level of help required
and then play against the computer.
JIC-678N (LPG,LNG) o)l.l)l)(J(J7,
MS-110 SWR METER
GAS LEAKAGE _....1 ~
~
for 27MHz
rroR
~
-~
)
~*SWRMeter.
DETEc I ·
~4"> J
=MT
_
KTIJO ,. . * *Power
Meter.
* Detects Propane, Butane and
, ~
AM Modulation Meter.
*
~~~l~~~s~:f:~d
audible
alarm.
* N.O./N.C. output for alarm
systems.
* 12 volt DC operation
·
UMYll5AL
-'""
F-t
•
-,i
~
-
~
~
r--',-...
!.
~
~
~
Sate guard your family and
your possessions.Gas leakage
can be fatal Ideal tor the car,
caravan, boat kitchen, etc.
~ * 1, 10, 100 watt switchable.
0
The TELE-ART RC700 Universal Remote Control Unit
can replace the infra-red remote controls of up to five
audio/video components br, simply learning and then
mimicking their remote con rot command codes. This
eliminates the confusion of which remote control to use
and does away with the clutter of too many remote
controls.
~
"'\0
n.'.~~\I
~~.,. "'~~
~(W
0
t:,
,...
~
•
._
* Can memorize up to 1T commands per component, \ . ~
s tots/ of 85 commands.
,; for
LCO display indicating function in use snd clock.
* ~ii;:i:;;,;,~':,i;~~;atically turn ON/OFF any one of ~
,; Countdown timer, can automatically turn ON/OFF
t
◄
~re ~:mO:rff.'e com;;;; $99.95 '
<~~
__,
.•
Limited Stocks !
only $39.95
<~ RG-58 52 Ohm
;. ·.~
~v
•.•.•:.••
•1
0
0
~ J,.
~~
0
now only $69.95
* FM Deviation Meter.
~ * Antenna Matcher.
r
~ ■ -=
~,~ ~ ,
,,.. ,
~
...._
~
,t[)fl([()~
COAX CABLE
~r
* Suitable for CB (HF) use,
ooN'roo;Lc;_;~~e;.;;;m;,;~~i: /ll/$#11/l
4 DIGIT COMBINATION LOCK KIT
AVM -1 AUDIO/VIDEO MIXER
This simple 4 digit combination lock has many applications,such
as accessing alarm systems, electronic doors, ignition killers,
or just about anything
* Operating voltage: 11-30V DC.
* Provision for battery back-up.
* 12V door strike to suit .. $39.95
Now tht1rt1 's a simple and int1xpt1nsive way to add narration, sound effects, and background
music to your vidt1o's after you have been out in tht1 field and shot them. rhis easy to uat1
mixer enables one microphont1 and up to three audio inputs to be added to Iha sound track
on the video tape. Ideal for the home movie buff. Each input has its own sept1rate audio
volume control for fading music etc. in and out as well as a mastsr control for output /t1vel
onJ $39.95
ll-<.111-<.•.......~■.: t=.1.............1.... 1
COS-5100TM
* 100MHz.
* 3 channel w ith delay.
* 5mV / DIV to 5V /DIV, DC to 100MHz.
* 2ns/DIV to 0.5s/DIV, both A and B.
* Includes 2 x 1:1 10:1 probes.
* 2 year warranty.
$285a00 lncl tax.
Oscilloscopes
COS-5060TM
* 60MHz.
COS-5041TM
* 5mV / DIV to 6V /DIV , DC to 60MHz.
* 5ns/DIV to 0.6s/DIV, both A and B.
* Includes 2 x 1:1 10:1 probes.
* 5mV/DIV to 5V/DIV, DC to 40MHz.
* A timebase: 20ns/DIV to 0.5s/DIV,(maln).
COS-5020TM
* 20MHz.
* 2 channel.
* 5mV/DIV to 5V/DIV, DC to 20MHz.
* 3 channel with delay.
* 40MHz.
* 2 channel with delay.
* 2 year warranty.
* Includes 2 x 1:1 10:1 probes.
* 20ns/DIV to 0.5s/DIV.
* Includes 2 x 1:1 10:1 probes.
* 2 year warranty.
$f37a00
$8Baoo
$1Boaoo
lncl tax.
* B timebase: 0.2us/DIV to 0.5ms/DIV,(delayed).
* 2 year warrany.
Inc/. tax.
Inc/. tax,
10
volt AC Plug Pack
*
*
*
10 volt AC o 1 amp.
Complete with 2.1mm DC type plug.
To suit many modems requiring
9 volt AC supply.
,,,
A VERY RARE PRODUCT!
DB-25 GENDER CHANGERS
. * NEW 7HIN" STYLE.
~1~ls· * Only 22mm long.
* Male to Male.
0-Q
,q,"1;
* Female to Female.
Variable AC
(Iual-timer
E L E C T RO NI C
Transrorrners
* HSN-0103
* HSN-0203
* HSN-0303
0-250V, o SA
0-270V, o 7 A
0-270V, o 13A
PLUS CLOCK
$159.00
$187.00
$314.00
A 24 hour dual timer/clock
with,· 2 count-down timers,
An enclosed, table-top variable transformer with
4mm captive head type and seperate earth
connectors. Largr, voltage control dial and a
clearly marked scale, housed in a steel case.
Only $8.50 ea.
MB-3 SPEAKER MOUNTING
BRACKET by •ARISTA•
FULL 12 MONTHS WARRANTY
RS232 LINE BOOSTER
Medium to heavy duty two platform bracket
designed tor mounting speakers to walls, desks,
ceilings, etc. Allows speaker lo be rotated a full
360 deg. as well as swivelled up and down.
2 preset memories. count-up
timer and clock.
Ideal for sports, maetings,
medication, cooking etc.
Displays Hours, Minutes and
seconds. Built-in alarms.
Having trouble with long RS232 cable lines
and then finding out your output level has
dropped and your not getting enough signal
down the line? II so, then you need a RS232
Line Booster.
Ths Line Booster can double your cab/a length.
Requires 12V DC supply o 100mA ... $13.95
PIR-30 PASSIVE
INFRA-RED DETECTOR
* 12 meter range o 90 deg.
* Walk test indicator.
* 8-18V DC operated.
* N.C. relay output.
* N.C. tamper output.
*
save $20.00
now
only
only
only
$49.95
$49.95
$29.95
PUICJ~S NJ~\\T LO\\T PUICJ~S N1~\\T LO\\T PUIC1~S NJ~\\T LO\\T PUICJ~S N1~ J,f1
FLUKE 87 FLUKE 85 FLUKE 83
FLUKE 77
FLUKE 75 FLUKE 73
only $19.95.
$676.00
$560.00
$466.00
$345.00
$258.00
$160.00
S~lDIUcl 1\\(YI .M~lN S~l[)IUcl 1\\0rI 1\\~lN S~lDIUcl .Mo<\.
AVS30 VIDEO TRANSMITTER
Ideal for watching a video in the bedroom. kitchen etc. without
having to move your complete VCR system or having long
extension cables runing from one end of the house to the other.
Output channel: UHF30
Transmitting distance: 10 mtr.
Complete with connecting cables
and power supply.
*
*
*
MOTORAD TL-301 TIMING LIGHT with
DIRECT READING ADVANCE SCALE
The TL-301 Advance Scale design is tor easy one-handed
operation of timing advance function. Leaves other hand free
to get access to those hard to see indicators.
Measures timing accurately up to 6000 RPM .
Test timing on all 12 volt conventional and electronic
ignition systems .... 4, 6 or 8 cylinders, including rotary motors
*
*
was $110.00
only $89.95
QO.C. approved
CITIZEN ED-3800
ELECTRONIC DIARY
Store Telephone No;s. Names and
Memo function. Schedules. 12/24
and Alarm, World Time, Calender.
Metric Conversion.
10KB memory.
3 llnes with 18
*
*
Addresses,
hr. Clock
Calculator.
char-acter-s.
CITIZEN ED-4500
CITIZEN ED-7800
Telephone Directory with Names and Addresses,
Calender. Memo, Schedules. Calculator. Metric
Conversion.
32KB memory.
6 llnes with 13 characters.
Telephone Directory, Schedules, Memo, 12/24
Clock with Alarm, World Time, Calender, Metric
Conversion. Currency Exchanger, PC Link.
32KB memory.
6 lines with 32 characters.
ELECTRONIC DIARY
*
*
ii
.
*
147 X 62 X 18mm
only $125.00
now
$79.95
*
132 X 65 X 13mm
David Reid
Bectronics
■
o nly $169.00
ELECTRONIC DIARY
*
*
IE!!:J
111111
*
154
X
82 X 19mm
only $275.00
127 York St. SYDNEY 2000 PH: (02) 267 1385
P.O. Box Q103, SYDNEY 2000 FAX: (02) 261 8905
SAME DAY MAILORDER DESPATCH*
CIC ~
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Poot ond Pockln9
$5 - $25 ........ S3.00
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$101 - $499 .... S8.00
$500 • ............ FREE
l~I II
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,
· -·
April 1991
HAD ENOUGH OF that pitiful
whine from your model steam
loco? This circuit makes a
realistic chuffing sound that
paces the loco speed. See p.22.
FEATURES
6 The World Solar Challenge by Gerry Nolan
The technology behind the race
16 Canon's New Still Video System by Bernard Malone
A marriage of CCD & floppy disc technology
64 A Practical Approach To Amplifier Design, Pt.2 by David Eather
Driver transistor selection & heatsink requirements
72 Hewlett Packard's Model 54600 100MHz CRO
The first of a new generation
PROJECTS TO BUILD
22 Build The SteamSound Simulator by Darren Yates
THE CONSTRUCTIONAL details
for our new garage door
controller begin on page 30 this
month. We also include a few
installation hints.
Give your model railroad some real atmosphere
•. ,,._,r
30 Remote Controller For Garage Doors, Pt.2 by Branco Justic
Construction plus installation
53 Simple 12/24V Light Chaser by Darren Yates
Four channels plus variable chase rate
56 Synthesised AM Stereo Tuner, Pt.3 by John Clarke
Final article gives the alignment details
"I\Wlf• 1.-001
SPECIAL COLUMNS
36 Vintage Radio by John Hill
Converting an Airzone to AGC
40 Serviceman's Log by the TV Serviceman
Mystery, mystery & frustration
74 Computer Bits by Jennifer Bonnitcha
Playing with the Ansi.sys fil e
~91.._
THIS MONTH, the Serviceman
took a wee peek at a Mitsubishi
TV set made in Scotland. It
frightened him. His story starts
onp.40.
78 Amateur Radio by Garry Cratt
The Easytune FSK indicator for HF transmissions
86 Remote Control by Bob Young
How pulse code modulation decoders were developed
DEPARTMENTS
3 Publisher's Letter
4 Mailbag
70 Circuit Notebook
81 Product Showcase
90 Back Issues
2
SILICON CHIP
92 Ask Silicon Chip
94 Subscription Page
95 Market Centre
96 Advertising Index
THIS LIGHT CHASER has four
separate channels, variable
chase rate & can operate from
12V or 24V DC. See p.53.
Publisher & Editor-in-Chief
PUBLISHER'S LETTER
Leo Simpson, B.Bus.
Editor
Greg Swain, B.Sc.(Hons.)
Technical Staff
John Clarke, B.E.( Elec.)
Robert Flynn
Darren Yates
Reader Services
Ann Jenkinson
Advertising Manager
Paul Buchtmann (02) 979 5644
Mobile: (018) 28 5532
Regular Contributors
Customer service - opportunity knocks
As I sit down to write this month's "Publisher's Letter", I have just
finished talking to one of the many sales representatives who come to
visit us every month. Not uncommonly, these reps are interested in
tapping into the lucrative electronics hobbyist market because they see
the apparent success of the big operators, some of whom advertise in this
magazine. But while they are attracted by the thought of new business
they are very much put off by the thought of having to sell directly to the
public. They somehow wish to gain some of the business of firms like
Dick Smith Electronics or Jaycar but without making any contact with the
actual customers.
Unfortunately, I don't have much sympathy for this view. For we also
hear a lot from readers or small firms who wish to buy from component
distributors who just won't deal with them. Quite simply, these organisations are turning away business. And, in the current economic climate,
they are turning away the very best business of all - it is called "cash
sales".
Now while having to set up a cash sales counter may cause a problem
for some firms, just think of the advantages. There is no need to invoice
customers. There are no bad debts with cash sales. The cash comes in,
often before the company has to pay for the goods it is selling. Need I go
on?
Some of the firms in question also worry about the high cost of providing each individual sale. They don't wish to make a $5 sale that they say
costs them $15. Well, does it really? The easy way around that problem is
to stipulate a minimum value cash sale which might be $10, for argument's sake. Now while the individual $10 sale might still be regarded as
a loss situation, at the end of the month, a bunch of these sales might
make a substantial contribution to overheads and might not be such a loss
after all. Also it might just be the case that the firm has not worked out the
true cost of its conventional invoiced sales.
The bottom line is service to the customer. If customers know that components are on sale from a firm they will eventually buy from that firm.
And you never know when a previously small customer may decide to
place a big order, solely on the basis of the good service he has had in the
past. On the other hand, if he's had the cold shoulder in the past, why
should he place the big order?
Is that how you think? I know I do.
Leo Simpson
Brendan Akhurst
Jennifer Bonnitcha, B.A.
Garry Cratt, VK2YBX
John Hill
Jim Lawler, MTETIA
Bryan Maher, M.E ., B.Sc.
Jim Yalden, VK2YGY
Bob Young
Photography
Glen Cameron
Editorial Advisory Panel
Philip Watson, MIREE, VK2ZPW
Norman Marks
Steve Payor, B.Sc. , B.E.
SILICON CHIP is published 12 times
a year by Silicon Chip Publications
Pty Ltd. All material copyright ©. No
part of this publication may be reproduced without prior written consent of the publisher.
Printing: Magazine Printers Pty
Ltd, Rozelle, NSW 2039; Macquarie
Print, Dubbo, NSW 2830.
Distribution: Network Distribution
Company.
Subscriptioa rates: $42 per year
in Australia. For overseas rates,
refer to the subscription page in
this issue.
Liability: Devices or circuits described in SILICON CHIP may be
covered by patents. SILICON CHIP
disclaims any liability for the infringement of such patents by the
maJ7ufacturing or selling of any such
equipment.
Editorial & advertising offices:
Unit 39, 5 Ponderosa Pde, Warriewood, NSW 2102. Postal address: PO Box 139, Collaroy Beach,
NSW 2097. Phone (02) 979 5644.
rax (02) 979 6503.
ISSN 1030-2662
APRIL 1991
3
MAILBAG
Bouquets for the
high energy ignition system
I have just completed assembly of
the 25th High Energy Ignition kit and
I wish to compliment you for making
the improvements that were incorporated in the version described in the
May 1990 issue . In particular, changing the 75V 1W zener diodes to 5W
units puts an end to the premature
failures in the original unit..
I use the older version (described
in the May & June 1988 issues) as a
demonstration for our apprentice fitter diesel students, as an introduction to simple electronics. Usually at
least two students per block purchase
the bits and fit it to their vehicles.
Having to assemble it teaches them
how to recognise values of resistors
and gives them a basic understanding
of the function of diodes, ICs, transistors and capacitors. And last but not
least, how to solder.
Thanks again for the improvements.
T. Merucci,
8 Mile Plains, Qld.
Does green dye
absorb laser light?
Thanks for the excellent article on
CDs and green pens in your December 1990 issue. I have noted that other
magazines have also indicated that
"green pens" have no demonstrable
effect on the music reproduction from
CDs .
However, I have not seen any comparison between the absorption spectrum of the green dye used in these
pens with the IR wavelength used in
the lasers that scan CDs.
M.J. Vincent's comment in Mailbag
(February 1991) is the closest suggestion I have come across to comparing
the dye's absorption spectrum with
the IR wavelength used .
Would it be possible to measure
th e absorption spectrum of the green
dye and to report your findings in
SILICON CHIP? (Organic Chemistry
Departments in local universities
should have suitable IR spectrometers
to do the job).
The wavelength of the IR radiation
from the scanning lasers in CD play4
SILICON CHIP
ers ~hould be available from published technical data. The obvious
statement is that if the green dye does
not absorb the IR wavelength used,
then the pens cannot possibly work.
C. G. Hodgson,
Wyong, NSW.
• We have been advised by the distributors of one of these pens that
they have figures on the absorption
spectrum of the green dye used in
these pens. Apparently, the green dye
does absorb the infrared light from
the lasers. However, even if the green
dye does absorb the laser light, that
does not mean that the pens work.
Fluorescent lights
do have drawbacks
I have just read your February editorial concerning fluorescent lights. I
agree with your comments about the
poor quality and impracticality of
many modern incandescent light fittings , but I do not support your statement to the effect that the declining
popularity of fluorescent lighting is
entirely due to some sort of conspiracy campaign by the trendy press.
While it is true that, in the past,
people have disliked fluoros because
the only fittings available were unattractive to look at, that wasn't the
only objection! What about the horrible starter circuits they almost universally used? Fluoro fittings are also
prone to buzz and hum and the tubes
often develop an annoying 50Hz
flicker long before they're worn out.
It's true that you can now get fittings in all sorts of attractive shapes,
and the new electronic ballasts alleviate the other problems, but there is
still a fatal (and little understood) flaw
in fluorescent lighting - they cannot
produce true white light!
True white light such as that produced by an Xenon discharge tube
has a uniform frequency spectrum.
That is, all wavelengths of light are
equally represented. When your eye
sees this type of light, the red, green
and blue cone cells on your retina
produce specific responses which
your brain has learned to interpret
collectively as the "colour" white.
SILICON CHIP,
PO Box 139,
Collaroy Beach 2097.
Now, while you can produce exactly the same sensation by mixing
together suitable proportions of red,
green and blue light, the illusion of
white light so produced only works
for white objects! For an extreme example, imagine a vivid yellow dye
which reflects strongly at a particular
yellow wavelength and absorbs all
others. When this is illuminated by
true white light, the wavelength it
reflects will stimulate both the red
and green cones on your retina, a situation your brain interprets as "yellow".
Now suppose we synthesised white
light by mixing red, green and blue
light from lasers (each of which produce only a single wavelength) . Under such light, white objects would
still look white, but the yellow dye
would look black, because there
would be no light of its particular
wavelength present!
The fluorescent powders used in
fluorescent tubes have a very "lumpy"
frequency spectrum, and the manufacturers normally use a mixture of
different colours to produce the illusion of various shades of"white". But
it is not really white and the "holes"
in the spectral response produce
unpredictable results with coloured
substances, perhaps not as extreme
as the example given above, but
enough to make people feel there's
"something wrong". That's probably
the main reason people still don't like
fluoros.
It's worth noting that in the film
and TV industries, fluorescent lighting would represent an enormous
saving in both power and installation
cost. The fact that the preferred light
source is still tungsten, followed by
HMI discharge lights, implies that
they must know something you don't!
K. Walters,
Lane Cove, NSW.
• It is true that most fluorescent tubes
do have a very lumpy light emission
spectrum. However, those manufactured for special applications such as
art galleries have a much more even
(whiter) spectrum, as well as having
low ultraviolet emission.
Voice recognition
for the deaf
I have a deaf fri end who is 87 years
old but otherwise in good health. I
am trying to find a way to help him.
In my copy of the USA magazine
"Monitoring Times", November 1990,
there is an article entitled "DSP: A
New Technology For Your Shack or
Listening Post".
It explains that through a Digital to
Analog Converter and a Digital Signal Processing microprocessor and
out through an Analogue to Digital
Converter, it is possible to accept
audio from a radio or TV and with an
interface and control, print it out or
view it on a computer screen.
For several months now I have been
trying to find a system which would
allow my friend to do just that, using
this system to read out the content of
radio or TV programs. I have just
about exhausted all avenues in New
Zealand, with many people telling
me of the big problems of speech recognition and cost of any equipment
to do this. Others do not know what I
am talking about.
I decided to write to ask if you or
your readers can throw any light on a
system of audio recognition. Initially,
I was thinking of a "Video Phone"
that would allow the deaf to make
phone calls and I am sure that I have
seen such a system described.
The following companies are li1-ted
as manufacturing the DSP system:
Advanced Electronic Applications,
2006 196th St SW, Lynwood, WA
98036, USA; LL Grace Communications , 41 Acadia Drive, Voorhees, New
Jersey 08043, USA; DRSI, 2065 Range
Road, Clearwater, Florida 346'25,
USA; and Intellhome, 571 Responsive Way, McKinney, Texas 75069,
USA.
I wrote to all these companies on
13th January but to date no reply.
Perhaps you or your readers can find
a way to help my friend and other
deaf people in this regard.
D. H. Rout,
Christchurch, NZ.
Criticism for
bias against FM
I've been enjoying Mr Young's
Remote Control column for some time
now. However, I'm moved to put pen
to paper over the many significant
errors in the December issue. His
admitted bias towards AM is fine and
I'd agree that the theoretical advantages of FM over AM are rarely
achieved in practice. However, he
then goes on to "prove" his case
against FM with many superlatives
such as "much more expensive ...
much more complex ... much higher
price".
None of these assertions stand the
most cursory examination. For example, examine the prices of AM and
FM sets. In the USA they are within
10% of each other. Here in NZ, a
Futaba 4 NBL AM set costs $274 and
the FM version costs $274.60. Maybe
it's my poor command of the Australian dialect of English , but I suspect
that 60 cents would not qualify for
"much more expensive"! Granted,
crystals are more expensive at $16
compared with $9 for AM sets, but
this does not reflect itself in the system prices.
The complexity he quotes is also
incorrect. Firstly, I challenge him to
show me a simpler AM transmitter
than the RCM&E FM one. Secondly,
his "simple" AM receiver has a component count of 61. Inspecting the
circuits of several similar quality FM
receivers, I find from 34 to 66 components. The average is 53 components.
The capture effect he quotes as a
serious disadvantage can be easily
demonstrated in the lab, but has never
been a problem in the "real world" of
the flying field, at least in the 13 years
I've been involved in FM R/C sets.
He then goes on to overplay the
difficulty of oscillator design in FM
sets. From personal design experience
in this area, I just cannot agree that it
is as difficult as he portrays. Likewise
the designers at Futaba, JR, Airtronics and Multiplex appear to find it
easy enough to design reliable and
cost-effective oscillators.
Don't get me wrong, there is nothing wrong with a preference for AM
sets, but the case should be argued
from a position of logic and with fac tual statements. He has done neither.
And as a final observation, his statement that 30MHz is about the limit
for fundamental crystals is also
wrong. A number of vendors offer
fundamentals to 70MHz and at least
one offers AT fundamentals to
300MHz.
Barry T. Lennox,
Wellington, NZ.
Bob Young
has his say
Errors? Differences of opinions certainly, but errors; definitely not. When
I wrote that article I knew with abso lute certainty that I was approaching
a Sacred Cow and that great care was
in order. I also knew I would get flak
because of my stance. I therefore had
the copy checked by an engineer well
versed in the design and service of
NBFSK R/C systems. I was of course
absolutely correct in my expectations
of flak. I did not, however, expect to
get that flak from as far afield as New
Zealand. Nice to know we circulate
widely.
Anyway, thanks for the letter. As
usual , I always learn something from
these exercises.
The crystal thing surprised me and
shows just how rapidly electronics is
advancing. There are indeed vendors
supplying fundamentals to 300MHz
and interestingly enough Garry Cratt's
article in the February 1991 issue
shows an MMIC oscillator using a
fundamental crystal at 330MHz. What
you neglected to mention however is
that these crystals are manufactured
under a new chemical etch process
and are even more expensive still.
My comment regarding fundamental crystals in the standard price range
having a limit of around 35MHz still
holds (at least in this country). However, as the world 's worst designer of
frequency multipliers, I certainly
welcome news of crystals being available at 300MHz and for that news I
thank you.
From here on your letter loses me.
You have in inverted commas, which
indicates a direct quote, a string of
superlatives which I just simply cannot find in my article; "much more
expensive ... much more complex ...
much higher price". Now "much more
expensive" means the same as "much
higher price" .
What I did say is "FM sets are expensive to purchase"; quoting from
the October 1990 Futaba (Aust.) price
list: AM 4ch set, $225: FM 4ch $275.
continued on page 89
APRIL 1991
5
World Solar Cha/le
Advances Electric
Whether people think about it or not, the
vehicles competing in the recent World
Solar Challenge were some of the most
advanced electric vehicles ever produced.
They are extremely efficient and quite
fast, as this report of the race indicates.
ROUND 350 BC, when Alexander asked Diogenes if he lacked
anything, Diogenes replied:
"Yea, that I do; that you stand out of
my sun a little". Perhaps he was only
speaking metaphorically but, to this
A
"Spirit of Biel 11" - the winner of
the 1990 World Solar Challenge. It
covered the 3007km route from
Darwin to Adelaide in just over 46
hours at an average speed of 65km/h.
6.
SILICON CHIP
day, we can't be sure that Diogenes
didn't mean that Alexander should
get out of the way of the sun shining
on his solar powered chariot.
Nothing much has changed. As
solar vehicles become more popular,
more people are bound to be asked,
with varying degrees of politeness,
"excuse me please old thing, would
you mind stepping out of the sunlight for a moment or two?"
Also unchanged since those times
is the amount of energy from the Sun
reaching the Earth's surface, around
lkW /m 2 • It may be as much as 1.3kWI
m 2 on some days because of energy
reflecting back from clouds but this is
not something to rely on.
The total amount of available energy will of course be altered by a
number of factors, such as: season,
latitude, time of day, cloud cover, air
pollution and so on; all of which we
have little direct control over.
What can be controlled, or ·at least
improved upon, is the percentage of
the available light energy that is converted to electrical energy to drive a
vehicle and/or be stored for later use.
And this is what the World Solar
Challenge (WSC) is all about - it provides the impetus, through competition, for contestants to improve every
aspect of their vehicle design and,
most importantly, the efficiency with
nge
Vehicles
·
which the Sun's energy is
converted for use.
The second World Solar Challenge started in
Darwin at 8:00am on 11
November, 1990 and
finished 3007km and 46
hours, 7 minutes and 51
seconds running-time
later, when the Spirit of
Biel II crossed the line in first
place with an average speed of
65.Zkm/h.
By GERRY NOLAN.
The elegant "Southern Cross". Its
multiple-curved panels are made
possible by the use of amorphoussilicon photovoltaic cells.
Experience pays off
During the race, it became apparent that the teams which competed in
the first WSC in 1987 were at a distinct advantage, the Spirit of Biel team
being a case in point. In 198 7, after
losing five hours in Alice Springs to
repair damage caused by what was
arguably the world's first collision
between a solar car and a conventional car, the first Spirit of Biel gained
third place. This time they won it.
This emphasises the tremendous
value of the World Solar Challenge
and the similar events that are proliferating around the world, as stimulus
to the development of practical solar
electric vehicles.
Not everyone, however, learnt from
their experience. Aquila, the "secondhand" Northern Territory University's
1987 Desert Rose, rebuilt by a team
from Dripstone High School in Darwin, had a drama when a bolt fell out,
allowing one front wheel to collapse the same bolt that had fallen out
and caused the same drama in 1987!
Ironically, the new Desert Rose had a
similar problem when a nut worked
loose and let one of its front wheels
fall off just after the 1990 start.
But these were the exceptions most of the experienced teams performed better the second time around,
in particular Hoxan's Phoebus, which
took over 153 hours the first time but,
Highly efficient solar cells are wired in a 'shingle' type arrangement so that the
entire surface of the panels is photoelectrically active. The shingle strings are
then assembled into modules.
in 1990, finished in 57 hours 21 minutes to gain fourth place.
Making solar cars faster
Most SILICON CHIP readers will al-
ready have a fairly good idea of the
factors influencing solar electric vehicle performance. What we are going
to look at more closely here is the
progress that has been made in these
APRIL 1991
7
Integration of the solar modules into the vehicle structure. The final solar
generator is over 17% efficient and, with a bright Sun, delivers 1300 watts,
making it the most efficient silicon gener.ator ever built.
areas since 1987. In particular, we'll
look at the progress made towards
more practical solar electric vehicles.
The most obvious factor influencing solar vehicle design is of course
the solar panels themselves - their
physical characteristics and their efficiency. Other factors include, in
roughly descending order of importance: battery performance, electrical
power transmission efficiency, mechanical power transmission efficiency, body weight and aerodynamic
efficiency, vehicle stability, rolling
friction and; the one that can assume
the most importance at any time,
structural integrity and reliability.
Solar cell efficiency
Wait a second - if the energy from
the Sun is free and virtually limitless,
why worry about efficiency? Well, of
course, it's a weight and space problem. If we could use an unlimited
area of solar cells, without worrying
about the weight, the efficiency with
which the solar energy was converted
to electrical energy wouldn't matter.
Obviously, in the case of a solar powered vehicle, we are limited.
8
SILICON CHIP
Solar, or photovoltaic cells (PVs),
were first developed in 195 7 and
NASA was the first organisation to
undertake large scale research and
development because it needed them
to run the batteries in satellites. Now
solar arrays are as much a part of
satellites as are wheels on cars.
Various combinations of chemicals
have been used in the search for
higher efficiencies but they have narrowed down to a few that either work
better than the others or are not prohibitively expensive.
Silicon cells have proven to be the
best option so far and vary in efficiency from 8-12% for amorphous
cells, 12-16% for monocrystalline and
more than 18% for laser grooved cells.
Hoxan Research Laboratories,
which fielded Phoebus III in the
event, claim 19.3% efficiency for their
mass produced PV cells, with 18.5%
efficiency when they are incorporated
into a module.
Laboratory calculations show that,
although 20% has long been regarded
as the practical limit for silicon solar
cells, the fundamental efficiency limit
was close to 28%, with 25% being a
reasonable experimental target.
Gallium arsenide cells are up to
18% efficient but are extremely expensive and the production processes
are not at all environmentally friendly,
so they haven't caught on.
The GM Sunraycer used mostly
gallium arsenide cells in 1987 b~t,
even though they gave it enough advantage to win, only the Sunraycer
clone, Solar Flair from California
State Polytechnic University, Pomona,
used them in 1990. However, it seems
their cells were seconds and they
gained little advantage, coming 11th
with an average 44.4km/h, compared
with the Sunraycer's average of
66.9km/h in 1987.
The Spirit of Biel team used the
"Green" laser grooved, silicon PV cells
with an innovative overlapping or
'shingle' arrangement to take advantage of the 'buried' contacts in the top
and bottom of the cells. This gave
them a packing density of 97.5% for
their panel array, with a resultant increased output for the allowable area
(see box for race rules).
Since the 1990 WSC, Dr Green's
team has announced that they have
achieved a further substantial increase
in efficiency with their laser grooved
(see Fig.1) buried contact, silicon photovoltaic cells. The laser grooves, in
two directions at right angles to each
other, form tiny inverted pyramids
that 'trap ' the light, reflecting it internally up to 50 times.
Amorphous silicon cells
Tipped by its developers, Semiconductor Energy Laboratories (SEL), to
be the first PV cells to enter large
scale mass production, amorphous
silicon cells were used on the very
elegant looking Mazda Southern
Cross in the 1990 WSC. Because
amorphous cells are not as efficient
as monocrystalline cells or laser
grooved cells, the Southern Cross took
97.5 hours to make 28th. However,
they are much cheaper to produce
and, because of their thin film construction, they are very flexible , making them easier both economically
and from a design point of view to
use for solar vehicles.
Sanyo has developed amorphous
silicon solar cells which need an
amorphous silicon layer only five
microns thick to produce PV activity,
about 1/60oth that for single crystal
silicon. Using amorphous silicon,
The sleek Hoxan "Phoebus III" looked as though it should have done better than
fourth. It covered the route in 57 hours & 21 minutes.
Below: "Phoebus III" spread out to catch the last few rays of sunlight just north
of Tennant Creek in the Northern Territory.
Sanyo has also developed a seethrough PV cloth which has already
been used to power the Sun Seeker
light aircraft on its attempt to fly
across America in July 1990. The aircraft remained airborne for 7 hours
and 35 minutes and covered a world
record breaking distance of 330km.
From a practical point of view,
amorphous solar cells are likely to
see widespread use as battery boosters on electric vehicles, electric sunroofs and so on, before the more efficient but more expensive cells.
The average of the energy generation potential from the solar arrays of
all the vehicles was around 1.3kW.
Lead-acid or silver-zinc?
Around half the cars in the 1990
WSC used lead-acid batteries and
most of the other half used silverzinc, the rest using nickel-zinc or none
at all. Battery capacities varied considerably, with the silver-zinc batteries having approximately twice the
capacity of the lead-acid types.
The first five cars home used sil-
ver-zinc batteries; the sixth, Australian Energy Research Laboratory's
(AERL) secondhand Ford from 1987,
used lead-acid cells. Apart from being
the first Australian built car to finish,
it completed the journey in a full day
and one hour less than it took in 1987,
when it used silver-zinc cells.
Perhaps even more significant is
that this car, with its $25,000 racing
budget, finished only three and a half
hours behind the million dollar second place Honda entry, after 60 hours
of racing!
Despite the success of the silverzinc cells, they are not yet a practical
option for urban vehicles because they
can easily be damaged if discharged
completely. They have a very high
initial cost, typically about $12,000
for competing cars, and they can only
be recharged about 15 times before
they lose much of their capacity.
Compare this with the relatively
low replacement cost of lead-acid
batteries, plus an expected 300 or
more charge/discharge cycles, and it
is obvious which is the more practical option. The Solar Star hasn't even
had the battery ·caps off in over
5000km of running, including the
WSC and the successful world speed
record attempt.
Besides , as can be seen from the
results of both the AERL car and the
Solar Star, they are not so far behind
in long range performance and well
ahead in outright speed.
Only two cars used nickel-zinc batteries. The first of these to finish,
Kyocera Corporation's Blue Eagle, was
the 14th car to cross the line, after
72.4 hours running. This car also used
a solar concentrator and a Stirling
engine to add to its solar power but
unfortunately the engine as well as
some of their batteries failed, so its
potential wasn't really tested.
Although they both used silver-zinc
batteries, one of the main factors credited for Spirit of Biel II's win over the
Honda car was its superior battery
capacity of 86, 25Ah cells connected
to give 129V, as opposed to Honda's
68, 20Ah cells connected to give 102V.
Two cars used no batteries at all.
The first of these to finish was Sofix
of Japan which, although the heaviest vehicle in the event at 290kg, finished in 21st position after 96.8 hours
running, most of it under overcast
conditions.
The other 'solar only car' was enAPRIL 1991
9
Dripstone High School's "Aquila" braves yet another big truck on the dusty
bitumen of the Stuart Highway. Note how its panels are tilted to capture the
morning sun.
tered by the Solar Research Association (Australia) and claimed 2 7th
position after running 97.3 hours.
Peak power trackers
Eight of the first 11 vehicles in the
1990 WSC ran Australian Energy
Research Laboratory (AERL) miniature, customised 'race trim' Maximizers, with 15 teams in total using
more than 50 Maximizers between
them. Ironically, although they had
purchased Maximizers, the secondplaced Honda entry didn't use them
as the team misunderstood the importance of peak power trackers
(PPT).
Spirit of Biel II used seven of their
own design PPTs, each handling
220W and weighing only 0.4kg. They
claimed an efficiency of up to 98.6%
at 30°C.
Just how important are they?
PPTs are to solar photovoltaics (PV)
what an automatic gearbox is to a car.
Both link the power source to the
load and permit the most efficient
operation by exactly matching the
power source at all times to the ever
changing requirements of the load.
The gearbox does this mechanically, while PPTs like the Maximizer
use a DC-DC step-down converter to
automatically maximize the electrical power delivered from the PV panels to the battery.
Generally speaking, each section of
the solar panels that can expect to
have the same amount of solar radiation reaching it at any one time should
have its own peak power tracker. This
reduces the need for 'averaging' between cells that are in shadow and
others that are in bright sunlight.
AERL claim that their Maximizer
PPT can easily produce 25% higher
battery charging rates than would be
achieved without the Maximizer
under the same conditions (ie, 25%
better on the day). Obviously, when
such an effort is being put into increasing the efficiency of solar cells
by a few percent, being able to achieve
up to 25% more by using PPTs is
more practical and cost effective.
Pride of Maryland, which placed
third in the US Sunrayce and was
one of the GM sponsored cars, used
10 NASA designed PPTs. Because
these relied on manual adjustments
to find the maximum power point for
each array, they proved unsatisfactory.
Desert Rose, run by the Northern
Territory University, used 26 PPTs
they designed themselves. These took
a 3ms sample of the open circuit voltage every two seconds and used an
open loop algorithm to establish the
optimum parameters through a 65kHz
FET chopper.
Because a relatively low battery
voltage (42V) was used, three DC-DC
converters were used to step the voltage up to 350V for the motor. Using
five FETs on each side of a push-pull
transformer, together with transformer
current sensing, the converters returned an amazing 97.8% efficiency.
Getting the power down
p-silicon
rear contact
oxide
Fig.1: diagram of the 23% efficient, laser grooved, silicon solar cell recently
developed by the University ofNSW and used on the "Spirit of Biel II",
winner of the 1990 World Solar Challenge.
10
SILICON CHIP
The Spirit of Biel II was able to
convert an astonishing 86% of the
solar energy collected to mechanical
energy at the drive wheel. Compare
that with the efficiency of converting
the energy contained in petroleum
fuel to mechanical energy!
Several of the cars used the powerful, lightweight UNIQ motors (see
SILICON CHIP, January 1991). The
overwhelming majority of competitors used DC motors, many of them
brushless DC permanent magnet
motors, including the winning Spirit
ofBiel II, which used a specially made
"Grundfos" clearly showing
the 'table top' construction of
its solar panel.
The Rules
"Grundfos" clearly showing what a willy willy can do to a car with 'table-top'
construction of its solar panels.
motor with a nominal power of 1.lkW
and a maximum power of 5kW.
Pride of Maryland was able to idle
along at about one eighth power most
of the time and take the hills in its
stride with its 14.9kW UNIQ motor,
unlike Konaweena High School from
Hawaii, whose UNIQ motor had so
much torque that it ripped itself right
out of its mountings!
But then, their Kalaikaka had other
problems such as their new Trogan
Pacer batteries being shipped to Auckland instead of Darwin so they only
had old lead-acid cells for the WSC, a
blown up DC-DC converter, many flat
tyres and so on. But they finished
18th after a run of 96.2 hours.
Transmission chains obviously play
a large part in getting the 'power to
the ground' and geared belts and
chains and sprockets were the most
popular way of transmitting the power
from the motors to the wheels and so
to the road - usually via small bicycle
type wheels.
Tests and experience have shown
that the narrow, high pressure tyres
reduce rolling resistance to a fraction
of the wider softer tyres. In many
cases, the wheels are streamlined with
plastic discs or wheel spats. The
successful Solar Star uses aluminium disc wheels and tyre pressures of
80kpa to achieve a rolling resistance
of only 0.004.
Body design
As well as low rolling resistance,
lightweight aerodynamically slippery
bodies are obviously of paramount
importance.
In many cases, to achieve the light
weight, strength and durability were
Essentially the vehicle has to
fit into a box six metres long,
two metres wide and one metre
high. Competitors can do virtu ally anything they like in that box,
as long as it's Sun-powered.
Sunlight is the only source of
power to be used for the racers.
More formally, the maximum
vehicle dimensions are 6m long
x 2m wide x 1.6m high.
The solar array may not exceed 4m long x 2m wide x 1.6m
high .
As many as four people are
allowed to share the driving,
each one ballasted to 85kg . If
you happen to weigh more than
85kg, plan ahead to lose weight,
have an operation or drive with
a weight penalty.
A handbrake, friction brakes,
brake lights, turn indicators, rear
vision viewers and seat belt/s
are required on all cars.
Cars may only race from
8:00am to 5:00pm each day and
must stop wherever they happen to be at 5:00pm.
Charging of the batteries, using only the car's solar panels,
is allowed from 6:00am to
8:00am and from 5:00pm to
7:00pm - after which, the car
must be put into a lightproof
container.
Vehicle maintenance or repairs may only be carried out
between 6:00am and 7:00pm.
Defective batteries may be replaced but only with a costly time
penalty.
After scrutineering, each car
will be accompanied by an official observer to ensure that all
the rules are complied with.
APRIL 1991
11
World Solar Challenge - Advancing Electric Vehicles
The instrument panel of the "Solar Star" showing the aircraft type steering
yoke, computer readout and neat array of switches. The keyboard port is on the
bottom right of the panel and the slot for the magnetic memory card on the
bottom left. During the WSC, the drivers were able to play computer games to
alleviate the boredom of travelling at a relatively low speed along a fairly
straight, flat road for hours at a time.
sacrificed, which.meant that time was
lost repairing cracks or even complete
structural failures. Most vehicles used
lightweight tubing , a la Sunraycer,
with a Nomex Kevlar sandwich body
to carry the solar panels.
To keep the profile down to a minimum, and consequently the coefficient of drag (Cd), the vehicle was
designed to be driven from almost
the prone position. Driver comfort is
also not unimportant on such a long
journey with fairly high pressure
tyres. A Cd of 0.12 was claimed by
several cars and the Spirit of Biel II
achieved 0.13 , all less than half the
Cd for the average family car.
was 2000km along the track when a
willy willy tore the complete panel
off, lifting the car, turning it over and
dumping it upside down in the process. The driver was unhurt but the
panel landed 50 metres away and
suddenly the race was over for the
Solvogn team from Denmark.
Dripstone High School had to restrict the speed of their Aquila if there
was any crosswind. Alarus, driven
by Dimitri Lajovic, was tipped over
by crosswinds several times and
Detlef Schmitz was sitting on the side
of the road having a cup of tea when a
willy willy destroyed his 5-wheeler
completely.
Stability
What was gained
One of the most publicised aspects
of the WSC is the stability test, in
which each vehicle has to drive at
full speed past a 58 wheel, 3-trailer
road train travelling at 80km/h in the
opposite direction.
All of the vehicles that competed
passed this test, but not all passed the
willy willy test further down the track.
Grundfos Pumps, one of the several "table top" models with solar
cells in a flat panel mounted on struts,
For the 3007km journey, Spirit of
Biel II consumed the equivalent of
12
SILICON CHIP
50kWh of energy which corresponds
to 0.165 litres of petrol per 100 kilometres or 4. 95 litres for the whole
journey! That's the equivalent of
2727mpg!
Old problems were redefined in
new ways and new problems manifested themselves.
Overall there was considerable
improvement in almost every area of
technology associated with the vehicles, their support crews and their
campaigns. More cars and people
participated, more was achieved for
less cost, and several million more
people in the world learnt about solar
cars and the potential of solar energy
through the tremendous amount of
publicity the event gained world
wide.
Personally, I think that, in the long
term, the Aquila team from Dripstone
Junior High School in Darwin have
cause to be more satisfied with their
effort than any other team. They set
out to demonstrate that schooling
should not be restricted to the class
room and that educational opportunities extend beyond the school - and
they succeeded admirably.
Their 28-member team took part in
a world class event at the cutting edge
of the most important technology
today and gained a credible 19th
place. This sort of participation can
be an inspiration for the rest of their
lives.
They will never forget it. Neither
will the rest of their school, their
families or their peers around the
world, to whom they have shown the
way.
SC
Changing the right hand rear disc
wheel on the "Solar Star". The motor
unit and ridged aluminium brake
drum can be seen here.
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$0.95
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$1.00
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$1.40
pF
1
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2.7
3.3
3.9
4. 7
5.6
6.8
8.2
10
12
15
18
22
27
33
39
47
56
68
82
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120
150
180
220
270
330
390
470
560
680
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7
YOUR EIGHT SPECIALTY STORES IN ONE
A trip to the
hardware store for
that latch set,
window lock or a
replacement part for
your plumbing
system should be a
simple matter - or is
it? Often, it isn't. But
all that could change
in the future.
By BERNARD MALONE*
A new way to store images
OU WALK into the hardware
shop with the confident air of
someone who knows exactly
what they want. Mere minutes later
you have acquired a feeling of gross
inadequacy after a sales assistant has
destroyed your confidence by asking
if the part is a left or right handed
fitting? Do you want brass or mild
steel? Do you want a flush or mortise
fitting, or is it a 50mm or 85mm backset with recessed rebate in a bright
annealed finish.
We are all familiar with trying desperately to draw word pictures of
what we need, only to leave the shop
with a sense of frustration after our
attempt at buying that special widget
turns sour.
All this may change soon as business recognises that today's low cost
image database technology can be
applied very easily to helping people
make buying decisions. Image database technology? Think of it as video
images and text stored in a computer
for easy access by customers and sales
staff.
Such technology is now well within
the reach of retail businesses. By using today's standard hardware with
locally developed software, a typical
trip to virtually any retail outlet would
change dramatically.
An image database
* Bernard Malone is Assistant National
Marketing Manager, Still Video Division,
Canon Australia Pty Ltd.
16
SILICON CHIP
Now when you go to the hardware
store, you march up to a screen and
let your fingers do the talking. The
system will very quickly let you
eliminate items that don't fit your
need and come to the final choice. It
may be a component for your new irrigation system, or a hard-to-describe
latch set for that door you are just
about to hang.
Having established exactly what
you need and having found that the
item is indeed in stock, you could be
on your way home in minutes. You
would be happy and the retailer
would have made a sale to a satisfied
customer.
Hang on - what retail establishment
has the time, inclination and resources to do this? Isn't this a bit of
crystal ball gazing? Definitely not.
Such a system is currently available
and at a relatively low cost.
How does such a system work? It
uses existing computer hardware,
Canon's ION Still Video camera is an
interesting marriage of CCD imager
and floppy disc technology. The
50mm floppy stores the analog signals
for 50 still pictures.
Viewfinder Unit
CCD Image Sensor
Shutter Unit
Display Panel
Lens
Battery Pack
White Balance
Sensor
Disk Drive Unit
Signal Processing Board
Flash
Signals from the ION camera can be viewed on a conventional PAL monitor and
you can step through them frame by frame. Image quality is about the same as
"still" frames from a typical HQ VHS video recorder.
new video hardware , and software
written especially for this application.
Image databases include images
and text together on a screen, where a
few simple keyword prompts will
search the images in the database.
The search brings up a montage or
individual images on screen that fit
your "idea" of what you want to buy
or examine.
Image databases are well suited to
establishments which have a very
large range of high value products.
Jewellery stores are a typical example.
Traditionally, sales staff have to remove trays of small valuable items
for a customer's inspection. A simple
image database would enable the assistant or th e customer to key in a few
simple "hints" of what they are look-
ing for and a series of products that
most closely fit the idea can be displayed.
Having reduced the alternatives, it
then becomes a much more practical
matter for the shop assistant to present these for a final decision by th e
customer.
So how does the shop capture and
handle these images? How quickly
does the system respond to enquiry
and how specific do the enquiry criteria need to be?
The key to image capture and handling is Canon's new range of Still
Video equipment, which overcomes
the cost and speed problems associated with scanning images, and a
newly developed image database software package.
Images are taken directly into the
system's software by using either the
Canon ION Still Video camera or the
Canon RE-552 Video Visualizer.
Canon's still video camera
The ION camera is quite small and
light - it fits in the palm of your hand
and will photograph 50 images on a
50mm floppy disc. The camera is
APRIL 1991
17
in playback mode, it produces conventional PAL composite video signals. Any of the 50 images on a floppy
disc may be displayed. Furthermore,
any image may be erased and replaced
by taking a new picture. So that is
one way of acquiring video images
for a database. The other way is with
the Video Visualizer.
Canon's Video Visualizer
The complete Canon setup for image processing and storage in a database
includes the ION camera, the Video Visualizer (which includes a built-in colour
camera with a zoom lens) and an AT or 386 computer with a 40Mb hard disc
and a VGA screen.
ideal for capturing large images such
as ladders, outdoor furniture, power
tools or garden implements. However,
it can be just as effective for photographing even small items down to
30cm shooting distance in macro
mode.
The Canon ION camera has a fixed
focus 11mm fZ.8 lens which is equivalent to a 60mm lens in a 35mm camera. It focuses normally to one metre
and down to 30cm when in the macro
mode.
There is a built-in flash with a
choice of shooting modes. When set
to "auto" , the flash will fire when the
camera senses low light conditions.
In the "on" mode, the flash will fire
on every shot.
A liquid crystal display (LCD) indicates the shooting mode, disc condition, track number, battery condition and self-timer. The camera is
powered by a long-life rechargeable
battery good for shooting 700 images
without flash. On battery power, the
camera will play back for 10 minutes.
The battery charger supplied with the
ION camera doubles as an AC adaptor for mains-powered playback.
Record, playback and erase facilities are all contained in the small,
lightweight unit. Exposure is adjusted
automatically and it has selectable
backlight exposure
compensation.
The ION 's CCD
imager converts the
lens image into video
signals which are recorded onto the 50mm
floppy disc in analog
format. The CCD has
786 pixels horizontally, enhanced by an
on-chip colour strip
filter for accurate
colour reproduction.
High picture quality is
achievable because the
camera uses "high
One of the benefits of the Still Video camera is that if
band" video circuitry.
some of the shots are unsatisfactory, you can just step
through to the wanted pictures and shoot them again.
When the camera is
18
SILICON CHIP
The RE-552 Video Visualizer is a
portable image input device which
includes a built-in colour video camera mounted above a document table
which is illuminated by fluorescent
side lights. The camera has an 8x
zoom lens and can be positioned for
close-ups. Focus, exposure and white
balance are all adjusted automatically.
The Visualizer lets you transfer virtually any image into your database from photographs, negatives, "lifting"
whole or part images from magazines,
drawings, transparencies and even 3dimensional objects.
The benefit of the Visualizer is that
images of large items can be easily
obtained from catalogs and illustrations, while a number of smaller items
can be grouped in the one image.
The Visualizer's camera: has a
420,000 pixel CCD sensor with horizontal resolution of 300 TV lines. The
main operating controls are located
along the front panel of the document
table with LED indicators above each
function control. There is a negative/
positive conversion button, a control
for auto white balance, and a manual
white balance control. You then have
an exposure compensation control
and manual and auto zoom controls.
When the "normal" camera position is selected, you can focus on objects or document surfaces ranging
from 335 x 250mm down to 43.3 x
32.4mm. If you want to capture
smaller objects, down to around 33 x
25mm, the "close up" position can be
selected. Three dimensional objects
present no problem, as the depth of
field of the camera in the "normal"
position will enable good focus on
objects about 50mm deep. The depth
of field diminishes in the close up
position.
Database software
The database software has been
designed by OSR Digital Video Systems (well known for their Super
Comms communications software)
Specifications
The ION is an electronic lens shutter camera which uses a 0.5-inch CCD
with 786 pixels horizontally, with a total of 230,000 pixels. The video signal
is PAL colour format which is recorded on a Still Video floppy disc. The
camera's lens is a built-in fixed-focus type with a macro mechanism for
extreme close-ups at 30cm.
Viewfinder: Heal image secondary imaging finder
Magnification: 0.55x
Finder Coverage: 84%
Dioptric Adjustment: -4 diopter to +2 diopter
Light Metering: Feedback AE with external photometric sensor and
CCD signal
Exposure Mode: Program AE (1/30 sec, f2.8 to 1/500 sec, f22)
Flash Sync Speed: 1/125 sec
White Balance: Automatic tracking system
Shooting Mode: Single image and continuous (3 images/sec) shooting
Self-Timer: 10 second delay
Video Output: 1Vp-p, 75Q unbalanced via 2.5mm mini-jack.
Horizontal Resolution: Recording/playback - 300 TV lines (min.);
playback - 350 lines (min.)
Playback Function: Playback single image or continuous images
(approx. 4 images/sec) by means of Forward or Reverse buttons.
Playback automatically cancelled when single-image display exceeds 2
minutes (when using battery pack) or 15 minutes (when using battery
charger)
Erasure Function: Single image erasure.
specifically for the storage and display of images which can be corn~
bined with text and field information.
This allows the user to define all
database categories from flat field to
multi-database search fields.
If a customer in a hardware store
was searching for a door latch set, for
example, the user may establish a
prime search using the field criteria.
For example, the input "door", "deadlock", "brass" and "stainless steel "
would invoke the database to allow
the searcher to see all products related to those criteria.
Free form text and word search allows the user to search for items
which may not be easily described by
the criteria. Alternatively, the searcher
can simply call up the database, for
instance "door accessories", and
browse through the multi-screen images and select the one he wants.
"Multi-layering" is also possible if
the user wants to be really clever. For
example, the searcher calls up an
image of a "door" and the image
would have several "highlight" points
such as "lock", "handle", etc. The
searcher would simply click with the
mouse on "lock" and the database
would then display multi -screen
images of the items in the "lock" database.
Rolling slide show
Another facility of the image database is its ability to be used by a
retailer to create a rolling slide show
of products while the system is not in
use - great for in-store promotions.
This can be done easily by designating a database called, "new products"
which would immediately commence
a continuous display of all new lines
in the shop.
Because video is being used, and
because of the simplicity of using the
Canon ION Still Video camera, setting up and editing of the image database is simple and time effective.
Unlike scanning, the user can very
quickly take a picture of the product
and quickly enter it into the image
database with a frame grabber, in-
eluded in the database software package. Again , because video is being
used, the amount of storage needed
for an image is much less than with
scanning. An average of 200Kb per
file is all the space needed , so a simple
complete system with 100Mb of hard
disc storage will store up to 500 images/files , including text and field
criteria.
One of the major advantages of the
OSR database is the ability to display
and view images on any VGA screen
without the need for a frame grabber.
OSR's colour conversion techniques
mean that when the image is captured by the Canon ION camera, it is
automatically converted to a VGA
format.
This means the user can have multiaccess systems without the need to
have a costly frame grabber in each
computer.
The speed at which images can be
retrieved depends on the computer
system being used. However, a typical enquiry from a basic system would
take only a few seconds.
This very sophisticated but simple
to use image database technology,
combined w ith Canon's new Still
Video technology, will benefit a wide
range of users. In fact, any organisation or individual that needs to identify, store and retrieve items from a
high volume of images or objects will
find the system extremely effective
and surprisingly economical and easy
to operate.
Paying the piper
A complete image database system
comprising a Canon ION (Image Online Network) Still Video camera and
database software and frame grabber
board will cost around $4500 . If you
don't already have a computer to run
the system, you will need a standard
AT or 386 computer with 640K of
RAM, 40 megabytes of hard disc and
a VGA screen.
The cost of the Canon ION Still
Video camera is $1300. The Video
Visualizer is $5200, while the image
database, including the frame grabber
board, is $3200.
In addition to viewing images on
screen, by adding a computer printer
to the system, the user gains the ability to produce hard copy of images or
complete database files. This can be
done in either colour or black and
white, depending on the printer. SC
APRIL 1991
19
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Size: 216
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look.
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',·,
Build the
SteamSound
Simulator
Had enough of that silly whine coming out of your
HO-scale "38" loco? This steam sound simulator
makes a realistic "chuffing" sound that keeps pace
with the loco speed.
T'S EARLY on a Saturday morning, about 7am, and you're relaxing in the leading carriage of a 5car set sitting on platform 1 at Central
Railway Station. Looking around your
compartment, you see a couple of
black and white photos framed with
scenes of the original Zig Zag railway
near Lithgow.
A "30 class" tank loco draws slowly
away from platform 2 with the empty
set from the overnight Southern Aurora that arrived half an hour ago. As
it moves into the distance, its highpitched whistle signals that it has
passed over the points, which now
revert to platform 1.
It's 7:04am and still no engine. The
whole station is alive with the sounds
of air compressors, people hurrying
to their seats and a stationmaster
mumbling something in the background.
You shove your head out through
I
DARREN YATES
22
SILICON CHIP
the window and in the distance see
big plumes of steam gently drifting
into the air. As it moves closer, you
can just make out the rear of the tender and the numbers on the back,
"3830".
All attention is focused on platform 1 as the guard comes up and
gets ready for the coupling. The carriage rocks violently back as the loco
hits the end buffers. The guard points
out to the driver in no uncertain fashion that he came in too fast. The driver
just leans out the window and points
to his watch. Three minutes to go.
The brake lines and coupling
hooked up, the familiar beat of the air
compressor starts as the fireman
stokes up the firebox with rich, black
Muswellbrook coal.
The guard, now leaning out of the
guard's van, blows his whistle and
holds out the green flag. The driver
acknowledges with a long flowing
blast of the whistle and eases
the throttle open. The whole
train groans as it moves
slowly out of the station. The
loco loses traction and slips, driving
wheels spinning, but the driver recovers it and the Southern Highlands
Express makes its way through the
yard and onwards.
This may be your memory of a
steam loco or maybe you're one of the
many who ventured to Hawkmount
and Fassifern to watch the 60 class
Garratts haul everything from coal to
concrete. Whatever the case, you have
to admit that a steam loco is infinitely
more interesting than your average
diesel - no bias intended, of course!
Model railways
Many of us have seen model railway layouts at exhibitions that depict
some place about 30 years ago, with
all the scenery carefully laid out to
look as realistic as possible. Then
you'll look down the track and see a
steam loco pulling the "pick-up"
goods train. Everything looks so realistic, until it passes you and you hear
the whine of the electric motor inside
the loco ... and the realism is lost.
This little project fixes that prob-
lem by producing a realistic chuffing
sound through a small speaker which
fits inside the guard's van or goods
wagon directly behind the loco. It's
specifically designed to go with our
Railpower train controller published
in the April and May 1988 issues of
SILICON CHIP. However, it it possible
to make it work with most other train
controllers (we show you how later
TO
TRACK
SAWTOOTH
WAVEFORM
GENERATOR
BRIDGE
RECTIFIER
VOLTAGE
REGULATOR
+12V
white noise source which is modulated by a sawtooth oscillator to produce the "chuffs". The speed (or frequency) of the sawtooth oscillator is
made directly proprortional to the
average DC voltage applied to the
loco's motor (via the rails) so that the
higher the DC voltage, the faster the
rate of chuffing.
The circuit is connected directly to
LOW
FREQUENCY
AMPLIFIER
POWER
AMPLIFIER/
BUFFER
DIODE
MODULATOR
WHITE
NOISE
SOURCE
Fig.1: block diagram of the SteamSound Simulator. The speed information is
derived from the track & this controls the frequency of a sawtooth oscillator.
The sawtooth oscillator in turns controls a diode modulator, which then
amplitude modulates a white noise source to produce the "chuffing " sound.
in the article). It's also easy to build
and uses no hard to get bits. In fact,
you'll probably already have most of
the parts in your junkbox.
Block diagram
Refer now to Fig.1 which shows
the block diagram of the SteamSound
Simulator. The circuit consists of a
the track via a bridge rectifier which
provides the power requirements fo r
the circuit and also provides the
throttle setting for the speed of the
"chuffs". The bridge rectifi er allows
the circuit to work correctly whether
the loco is moving forwards or backwards.
As mentioned earlier, the circuit
was designed primarily for use with a
pulse typ e train controller so before
we go any further, let's go over the
basic principles of PWM train control
so that we understand what is meant
by the terms "positive pulses" and
"varying pulse width".
All model locos use a simple
method of transforming electricity to
movement: you apply a voltage to the
little motor and the loco
moves. The higher the voltage, the faster it goes. OK, that
should be obvious. However,
at low voltages and due to dirt
on the rails or the wheels, the
motor will tend to not operate
smoothly and may often stall
on gradients and curves.
By applying a pulsed DC
voltage to the motor, we get
much better speed regulation
an d hence smooth running at
low speeds. The loco will also
start smoothly, without any of the
jerkiness associated with conventional controllers.
Fig. 2 shows how a PWM controller
works. If narrow pulses are applied
to the rails (as at the top of the diagram), then the motor averages these
pulses out, so that in effect we have a
small voltage across the motor. As the
pulse width increases, the average
voltage increases, which in turn,
APRIL 1991
23
SLOW SPEEO PRODUCES NARROW PULSES
MEOIUM SPEEO PRODUCES HALF-WIDTH PULSES
j
FAST SPEEO PRODUCES VERY WIDE POSITIVE PULSES
Fig.2: how a PWM controller works.
At low speed settings, only narrow
pulses are applied to the rails to
produce a low average voltage. At
higher speed settings, the pulse width
is increased to produce a higher
average voltage across the motor.
makes the loco speed up. Finally, if
we have very wide positive pulses,
the average voltage is very high and
so the loco speeds around the track.
· Now if we go back to the block
diagram of Fig.1, the output of the
bridge rectifier is fed to a voltage regulator which provides +12 volts DC to
power the circuit. It is also sent to a
voltage inverter stage and this controls the sawtooth oscillator.
The reason for the inversion is to
provide the correct control voltage for
the oscillator so that we get the desired output; ie, to produce a low
frequency output, we need a high
voltage on the input and to produce a
high freqeuncy output, we need a low
voltage on the input. In effect, the
sawtooth oscillator works the wrong
way around, so we need to invert the
incoming voltage to compensate.
From the oscillator, we get a
sawtooth output with a frequency
proportional to the pulse width of the
track voltage. To put it simply, the
faster the train is going, the higher
the frequency from the oscillator.
This output is then fed to a diode
modulator. To explain briefly, the
conductivity of a diode changes depending on the voltage across it. This
means that a diode with 0.6 volts
across it will conduct more current
than a diode with only 0.2 volts across
it.
In effect, we are using the diode as
a voltage-controlled resistor but more
about this later.
Meanwhile, the white noise generator produces about 80mV of signal
which makes up the steam and
chuffing sound. By modulating or
varying this signal, we can produce
the effect of a train chuffing up a
fairly steep hill or blasting along the
flat.
The white noise signal is modulated by feeding it to a low frequency
amplifier and by using the diode
modulator to vary the gain of this
Our prototype SteamSound Simulator was built into a HO baggage van from
Powerline Models Pty Ltd. Power for the circuit can be picked up by running
leads through to the loco motor or by using a pick-up system from the rails.
Using the SteamSound Simulator with the Simple Train Controller
OK, can you use the SteamSound
Simulator with the Simple Train Controller described in our November
1990 issue? The answer is yes but
you do have to make a few minor
modifications. You can use the same
modifications to make the SteamSound Simulator work with just
about any train controller.
First, because of the way in which
the Simple Train Controller works
(ie, without a pulsed DC output),
you will not be able to power the
SteamSound Simulator directly from
the rails. Instead, it will have to be
powered from a separate DC sup-
24
SILICON CHIP
ply. That in turn means that the project can no longer be mounted inside a carriage but you can mount it
in a fixed position under the layout.
If you're willing to accept that limitation, here are the modifications:
(1 ). Disconnect the anode of diode
D5 from the bridge rectifier and connect it instead to the external DC
supply. This could be a 12V DC
plugpack supply (which will give an
output of about 16-1 ?V when lightly
loaded}. Alternatively, you could use
the supply rail to the train controller
itself provided it is in the range 1518V DC; or you can use some other
external DC supply up to about 25V.
(2). Delete the 1.8kQ resistor connected to the bridge rectifier.
(3). Change the 330kQ resistor on
O2's base to 120kQ, the 27kQ resistor to 150kQ, and the 150kQ resistor to a 10kQ trimpot (tie the wiper
to one of the outside pins).
Note that you still must connect
the SteamSound Simulator to the
track via the bridge rectifier to derive the speed information. The trimpot is simply adjusted for best effect
(ie, steam only when the throttle is
closed, with the "chuffs" starting as
the throttle is opened).
05
1N4004
100 . +
l5VW+
WHITE NOISE
SOURCE
14
.,.
0.1
.,.
1.2M
FROM
TRACK
.001
1k.
LOW FREQUENCY
AMPLIFIER
150k
06
1N914
.0471
HIGH GAIN
AMPLIFIER
.,.
07
01+ 1N914
POWER AMPLIFIER/BUFFER
DIODE
MODULATOR
+12V
27k
+12V
0.11
15k
B
.,.
~
1.8k
E'Oc
VIEWED FROM
BELOW
.,.
+12V
SAWTOOTH
GENERATOR
.,.
STEAM SOUND SIMULATOR
Fig.3: the final circuit is based mainly on an LM324 quad op amp IC. D1-D4
rectify the track voltage & this controls the frequency of the sawtooth generator
based on Q2 & ICla. Ql is the white noise source. Its output is fed to IClb where
it is amplitude modulated by diode modulator D7 to produce the "chuffing"
sound. The output ofIClb is then amplified & fed to the loudspeaker.
stage. This low-pass active filter stage
amplifies the white noise and removes
the high frequencies so that our
"chuffs" have a bit more grunt to
them.
The output from the low frequency
amplifier is then fed to a high gain
amplifier. This stage amplifies the
signal to a level suitable for driving
the power amplifier and loudspeaker
stages.
Main circuit
Take a look now at Fig.3 . It's based
mainly on a single LM324 quad op
amp to keep the parts count fairly
low.
Diodes Dl-D4 full wave rectify the
PWM track voltage to produce the
positive DC voltage pulses. This is
then coupled via isolating diode D5
to a .7812 3-terminal regulator which
produces a +12V DC rail. This rail
directly provides power for the audio
output transistors (Q3 & Q4) and is
also decoupled using a 22Q resistor
and 470µF capacitor to provide power
for the small-signal circuitry (Ql, QZ
and ICl).
The positive-going pulses from the
bridge rectifier are also fed to transistor QZ which forms the voltage inverter. The output signal appears at
QZ's collector and is fed to a filter
network consisting of a 6.8kQ resistor and l0µF capacitor.
This filter network has two functions: first, it filters and averages the
pulses to provide a steady DC voltage; and second, it forms part of the
timing network for the sawtooth oscillator based on ICla.
ICla is 1/4 of an LM324 quad op
amp, connected as a standard Schmitt
trigger squarewave oscillator but with
a couple of changes. To start with, the
oscillator uses the voltage derived
from QZ to determine its frequency,
so that it really acts as a voltage-controlled oscillator or VCO.
Diode D6, connected ·in the negative feedback loop of the op amp,
causes the output signal to be a series
of short pulses.
Let's now take a closer look at how
The top trace of
this CRO
photograph shows
the waveform
across the speaker,
while the bottom
trace shows the
waveform at the
output of the
sawtooth generator
(pin 9 of ICla).
CRO settings:
upper trace 0.lV/
cm & 20ms/div;
lower trace 0.5V/
cm & 20ms/div.
APRIL 1991
25
15k
01-04;::
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22Q
01 330k
05 1a12
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22k
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0.1
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68k
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68k
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10
[!]12;~r<at>O uF
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03
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C)1oouF
04 • 25VW
+
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TRACK
Fig.4: check each resistor with a multimeter before installing it on the PC board
to make sure you have the correct value. The resistors are all mounted end-on
to save space. The type numbers & pinouts for the transistors (Q1-Q4) can be
gleaned from the main circuit diagram (Fig. 3).
this oscillator works.
Initially, the lOµF capacitor has no
voltage across it and so the output of
ICla (pin 8) is high. The capacitor
now quickly charges via the 1.ZkQ
resistor and D6 until it reaches the
upper threshold level of the op amp
(ie, the voltage on pin 10), as set by
the two 68kQ and the 120kQ resistors. When it reaches this level, pin 8
switches low but this plays no part in
discharging the lOµF capacitor because D6 is now reversed biased.
Instead, the lOµF capacitor discharges via the 6.8kQ resistor to whatever voltage is at QZ 's collector. This
voltage determines the time it takes
for the capacitor to discharge to the
lower threshold level, at which point
pin 8 switches high again and the
cycle repeats.
The lower the voltage at QZ's collector, the faster the capacitor discharges and therefore the higher the
CAPACITOR CODES
0
0
0
0
0
Value
IEC Code
EIA Code
0.1µF
.068µF
.047µF
.001µF
100n
68n
47n
1n
104
683
473
102
output frequency. Since the voltage
at QZ's collector is inversely proportional to the track pulse width, it follows that the oscillator speeds up as
the train speed increases.
The waveform across the lOµF capacitor is sawtooth shaped and this
matches the waveform of a real
"chuff" amazingly well. This signal
is then fed to the anode of diode D7
via 150kQ and 330kQ resistors. The
O. lµF capacitor at the junction of
these two resistors is used to filter the
PARTS LIST
1 PC board, code SC09104911,
108 x 28mm
1 32mm 8Q loudspeaker (IRH
KSS-3108)
Semiconductors
1 LM324 quad op amp (IC1)
1 7812 12V regulator
2 BC548 NPN transistors
(01 ,02)
1 BC337 NPN transistor (03)
1 BC327 PNP transistor (04)
5 1N4004 rectifier diodes
(D1-D5)
2 1N914 signal diodes (D6,D7)
Capacitors
1 470µF 25VW electrolytic
2 100µF 25VW electrolytic
26
SILICON CHIP
2 10µF 16VW electrolytic
6 0.1 µF monolithic
1 .068µF monolithic
1 .047µF monolithic
1 .001 µF monolithic
Resistors (0.25W, 5%)
1 1.2MQ
1 15kQ
1 560kQ
1 6.8kQ
2 330kQ
1 1.8kQ
2 150kQ
1 1.2kQ
1 120kQ
1 1kQ
3 100kQ
1 820Q
2 68kQ
1 22Q
2 27kQ
1 10Q
1 22kQ
Miscellaneous
Solder, hookup wire, etc.
waveform and to prevent "clicks" in
the output.
Diode modulator
D7 is the diode modulator stage
depicted in Fig.1. Its cathode is connected to a voltage divider (27kQ &
15kQ) which sets the bias to about 4.3
volts. This provides us with a preset
level and balance so that we don 't get
too much steam and not enough chuff.
The 0. lµF capacitor on D7 's cathode
provides a low-impedance AC path
to ground, so that we get maximum
effect from the modulation.
Whenever the DC level of the
sawtooth waveform rises above 4.3
volts , the diode begins to turn on and
this decreases its AC impedance. The
.068µF capacitor thus sees a progressively lower impedance to ground as
the voltage across D7 increases.
Because IClb is connected as a noninverting amplifier, these impedance
variations directly control its gain. If .
the impedance goes down, the gain
goes up. Conversely, if the impedance goes up, the gain goes down.
Thus, D7 modulates the gain of IC7b
to provide the "chuffing" effect.
White noise source
Transistor Ql is used as the white
noise source. This transistor is connected as a reverse biased diode (ie,
the base-emitter junction is reversed
biased) and the resulting noise is
coupled via a O. lµF capacitor to pin
12 of IClb. IClb functions as a noninverting amplifier with modulated
gain, as detailed above. The .OOlµF
capacitor in the feedback loop rolls
off the upper frequency response of
this stage.
The modulated output from IClb
appears at pin 14 and is direct coupled
to non-inverting amplifier stage IClc.
From here, the signal is passed to pin
3 of ICld which, together with transistors Q3 and Q4 , forms the output
stage. Q3 and Q4 buffer the output of
the op amp to provide current gain
and are connected inside the feedback loop to minimise distortion.
The lOQ resistor and the 0. lµF capacitor at the output form a Zobel
network, which stops the circuit from
oscillating. The output signal is
coupled to the loudspeaker via a
lOµF capacitor. A value of lOµF might
seem a bit puny for a normal amplifier but since it is only handling
modulated white noise there is very
little low frequency information and
so a small capacitor can be used.
For the same reason (ie , no low
frequencies), a small speaker can be
used and still provide quite a surprising level of steam sound output.
Construction
All components except for the loudspeaker are mounted on a small PC
board. This is coded SC09104911 and
measures 108 x 28mm. The board,
along with the recommended loudspeaker, can be installed in any carriage that's long enough to accommodate it; eg, a guard 's van or goods
wagon.
Before you start assembly of the
board, carefully check the tracks for
shorts or breaks. Any faults should
be corrected at this stage. Also
make sure that the board
will fit into the selected van or
wagon - you
don't want to
be doing
surgery on
it when it's
full y assembled.
Once you
are satisfied
with the PC
board itself,
take a look at
the wmng diagram (Fig.4) , which
shows how the components should
be installed. Make sure you follow it
precisely otherwise you may have
problems fitting all the components
onto the board because of the cramped
conditions.
Begin by installing the four wire
links, making sure that they are flush
with the board and as straight as
possible. This done , you can
install the resistors. These
are all installed end on
to save space, as
shown in the wiring
diagram and in the
photograph.
Uffi
a pair of
needle nose
pliers to make neat right
angle bends in the resistor
leads. This will give your
board a much neater appearance
and reduce the possibility of
shorts between components.
Now you can install the monolithic
capacitors. These should
all have a fixed spacing of
5mm between their leads, regardless of their value. Don't try
using greencaps here - they will be
too bulky.
After you've installed these capacitors, wire in the signal and power
diodes. Make sure that the correct
type is used at each position and that
they are install·ed the right way
around, otherwise the circuit may end
up acting like a short circuit!
Next, install the four transistors.
The reason for doing these now is
that they are lower in profile than the
RESISTOR COLOUR CODES
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
No.
Value
4-Band Code (5%)
5-Band Code (1%)
1
1
2
2
1
3
2
2
1.2MQ
560kQ
330kQ
150kQ
120kQ
100kQ
68kQ
27kQ
22kQ
15kQ
6.8kQ
1.8kQ
1.2kQ
1kQ
820Q
22Q
10Q
brown red green gold
green blue yellow gold
orange orange yellow gold
brown green yellow gold
brown red yellow gold
brown black yellow gold
blue grey orange gold
red violet orange gold
red red orange gold
brown green orange gold
blue grey red gold
brown grey red gold
brown red red gold
brown black red gold
grey red brown gold
red red black gold
brown black black gold
brown red black yellow brown
green blue black orange brown
orange orange black orange brown
brown green black orange brown
brown red black orange brown
brown bla9k black orange brown
blue grey black red brown
red violet black red brown
red red black red brown
brown green black red brown
blue grey 6Iack brown brown
brown grey black brown brown
brown red black brown brown
brown black black brown brown
grey red black black brown
red red black gold brown
brown black black gold brown
1
1
APRIL 1991
27
Three holes were drilled in the bottom of the carriage to let the sound out. The
miniature loudspeaker sits in an adjacent rectangular cutout and protrudes
slightly from the underside of the carriage.
electrolytic capacitors. Once again,
make sure that they are installed correctly. The pinout diagrams are on
the circuit schematic (Fig.3).
Now you can install the electrolytic capacitors. Although they may
look a tight fit, these capacitors fit in
snugly if you use the recommended
voltage rating. Check that the polarity
of each capacitor is correct, too.
Finally, solder in the 7812 regulator and the LM324 op amp IC. You
can easily identify pin 1 of the IG by
the adjacent notch (or dot) in the plastic body. When you've finished, check
_the board carefully for solder splashes
and dry joints. If everything _is OK,
you can connect up the loudspeaker
and the train controller.
To test the board, connect the track
leads directly to the controller and
apply power with the throttle fully
closed. If the overload alarm sounds ,
switch off immediately and check
your wiring for a short or an incorrectly installed component.
If all is well, the circuit will make a
continuous sound that simulates the
noise of escaping steam. If you now
open the throttle (that's railway talk
for increasing the speed), the steam
sound should slowly decrease in volume until the circuit begins to chuff.
As you continue to open the throttle ,
the speed of the chuffing should also
increase.
Installation
When you install the board inside
the carriage, you can use Blu-tac® to
Fig.5: this is the full-size artwork for the PC board._
28
SILICON CHIP
hold it down. The way in which the
power supply is connected is up to
you. You may wish to connect the
power directly from the motor of the
loco or you may wish to use a collector system from the wheels or rails.
The choice is yours.
We mounted our prototype into a
New South Wales HO baggage car
made by Powerline Models Pty Ltd
(047 39 6204). We drilled three 10mm
holes in the base of the carriage to let
the sound escape and also made a
rectangular cutout to accept the loudspeaker which protrudes slightly from
the underside of the carriage.
If you intend mounting the SteamSound Simulator underneath your
layout baseboard, you can use a much
larger speaker and thereby get a lot
more sound. Another good idea which
we tried was to have one SteamSound
Simulator behind the loco and one
underneath the layout baseboard.
Because the two simulators are not
synchronised, they give an interesting echo effect as the train moves
around the layout.
Which ever way you do it, you can
now stop using your imagination and
actually have the sounds of steam
around your layout! (Oh, what joy!
No more diesels ... oops! Only joking,
of course!)
SC
wpoD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR: C
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Lane Cove West, N.S.W. P.O. Box 671, Lane Cove N.S.W. 2066
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8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday.
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Tax exemption certificates accepted if line value exceeds $10.00.
BANKCARD, MASTERCARD, VISA, CHEQUES OR CASH CHEERFULLY ACCEPTED
:i:
'ti
"'
Remote controller
for garage doors, Pt.2
Last month, we presented the full circuit
details for this project which essentially
consists of a receiver/decoder board plus a
ready built transmitter. This month, we give
the constructional details and discuss how it
can be used in a practical installation.
By BRANCO JUSTIC
We left off last month with a short
discussion on the transmitter circuit
which was shown on page 20 of that
issue. It is supplied readymade and
operational but it needs one component change and it must be coded.
The component to be changed is the
resistor connected between pins 15
30
SILICON CHIP
and 16 of ICl. Shown on the circuit
last month as lMQ, it needs to be
changed to 220kQ. We suggest you
change it and do the transmitter coding at the same time, to avoid unnecessary work.
Before proceeding to modify the
transmitter though, it is better to per-
haps leave it for the moment in its
supplied condition. So let's proceed
to the assembly of the receiver/decoder board.
As shown in the photographs, the
receiver board has five SPDT relays
mounted on it and these are supplied
with the kit. We suggest that they be
mounted on the board first, before all
the other circuit components. There
is just one small but very important
point though. Five diodes and two
resistors mount under those relays,
so you'd better bung them in as the
first step otherwise you will be more
than a little cheesed off later on.
Consult the wiring diagram of Fig.4
and you will see that the five diodes
in question mount right underneath
the relay coils. The two lOQ 1 W resistors actually sit between relays
TO BATTERY
POSITIVE
Fig.4: this diagram shows the component layout for the receiver/decoder board,
as well as the external wiring. Note that a diode sits underneath each relay coil
and should be installed before the relays are mounted. The same goes for the
two 10Q 1 W resistors.
RLA 1 and RLA2, and between RLA3
and RLA4.
24 V operation
Another diversion, before we get
too involved with the construction,
concerns the supply rail. We assume
that most constructors will want to
use a standard 12V automotive wiper
motor and gearbox as the motive
power for their garage door opener.
These motors are quite efficient but
have loads of torque since they are
geared down a long way. Another
option is to use a 24 V truck or bus
wiper motor. If so, you will want to
run the circuit at 24V. That means the
two aforementioned resistors will
need to be 120Q 2W units.
We'll have more to say about the
power supply arrangements later;
back to the board assembly.
Next, install the five diodes and
two resistors and solder them in place.
Make sure that the diodes are soldered in the right way around.
It is important that the relays be
carefully soldered into circuit, otherwise they will not work. Why? Because their metal frame is actually
connected to the moving switch contact. If the frame is not soldered prop-
erly, the relay will, for all intents and
purposes , be open circuit.
For that reason , make sure that the
mounting lugs on the relay fram es are
clean and bright. If they're not, clean
them up with a Scotchbrite scouring
pad. Don't, whatever you do , use steel
wool. It will inevitably leave stray
strands on the relay which will probably cause a future short circuit.
When the relay mounting lugs are
clean and bright, tin them carefully
with your soldering iron (making sure
that you only give them the lightest
touch of solder). That done, push
them all the way into their respective
board holes and solder them to the
board's copper pattern.
You can now begin installing the
smaller components, starting with the
wire links, diodes and resistors. Note
that some of the resistors are mounted
end-on, because space is a bit tight.
Now put in the capacitors. There
are quite a few electrolytics - make
sure that they are all correctly polarised, as shown on Fig.4, before you
solder them into place.
The last components to be mounted
are the transistors and diodes and
naturally, it is vital that they too are
installed the right way around. Sock-
ets are optional for the !Cs; use them
if you want to.
Finally, we fitted a 350mm insulated antenna lead to the receiver. We
coiled the lead as shown in the photograph to keep the installation neat
but it should be left straight if you
want maximum range.
When the board is complete, go
over it very carefully to check component placement and your soldering. Fix any mistakes now.
Now is the time to change that lMQ
Our prototype was installed in a large
plastic case, with the 12V light fitting
mounted on the front panel. Also
mounted on the front panel is the
pushbutton switch which provides
manual UP/DOWN operation.
APRIL 1991
31
cut the relevant tracks to the data
pins for ICl. Note that A4, A9 and
All should be open circuit when you
are finished (for this example, anyway) .
Now, on the receiver/decoder
board, use your soldering iron and a
little solder to bridge (ie , short out
with solder) all the desired high or
low connections for Al, A2, A3, A6,
A7, A8, A10 and A12.
One thing you must be sure to avoid
and is that you don't have bridges
from one of the IC pins to both HI and
LO. If that happens, you short the HI
rail (which is protected on the transmitter board by a 10kQ resistor) and
the circuit won't work. On the receiver, the 7808 providing the +8V
rail should protect itself but the circuit still won't work.
Power check
This interior view of the prototype shows the receiver/decoder board and some
of the external wiring. The battery is in place but not yet connected or bolted
down. Note the coiled antenna lead near the lefthand side of the case.
resistor in the transmitter to 220kQ,
as mentionend at the start. Unclip the
transmitter case, disconnect the battery, desolder the lMQ resistor and
solder in the 220kQ unit. Now for the
coding.
The important thing to note about
the transmi_tter and receiver coding is
that they must be absolutely the same.
If even one of the coding bits is different, you can press that transmitter
button till the battery runs out and
the receiver will continue to sit there
and do nothing.Make absolutely sure
that the coding is correct.
How to code
This part is where you program the
transmitter and receiver with your
own unique code. You do it by connecting various pins on the transmitter encoder (ICl) and the receiver
decoder (IC2) high, low or leaving
them open circuit. Fig.5 shows the
general concept. It shows the copper
PC pattern underneath both these ICs.
You can see the IC pads and the
HI
associated HI (+V) and LO (0V)
~
rails.
c»
A1
c»
C> A2·
On the transmitter, there are tiny
c»
c». A3
tracks tying each data pin to the
C>
A4
c»
c» A5
HI and LO rails. You'll need to cut
A12 C>
A6
one or both of these tracks on each
A11 C>
A7
A10 C>
0
AB
data pin, to perform the coding.
A9
On the receiver/decoder board,
each of the data pins is unconnected and you will have to deRECEIVER
TRANSMITTER
cide whether to bridge each of the
Fig.5: these are portions of the copper
pins HI, LO or leave them unconPC pattern underneath the transmitter
nected.
encoder (IC1) and the receiver
Now we'll give you an example
decoder (IC2). You must cut one or
of how to do it.
both of the bridging tracks on all the
Suppose you decide to make the
data pins for the transmitter (left) and
transmitter
coding as follows: Al,
use your soldering iron to bridge the
A3, A6 and A10 all high; A2, A7,
data pins HI or LO on the receiver.
A8 and Al2 all low; and all other
The coding for the transmitter and
lines open circuit. To do this, you
receiver must be identical otherwise
the radio link will not work.
simply use your utility knife to
32
SILICON CHIP
To check the receiver/decoder operation, you'll need either a 12V AC
or DC plugpack; it does not matter
which.
When power is applied to the receiver PC board, the light relay (RLA5)
and the "Down" relays (RLA3 &
RLA4) should operate. After about 2
minutes, the light relay RLA5 should
drop out but RLA3 and RLA4 should
remain latched. If the manual pushbutton is now pressed, the light relay
RLA5 should once again operate, relays RLA3 and RLA4 should drop out,
and the "Up" relays RLA1 and RLA2
should operate. To drop out the "Up"
and the "Down" relays, you will have
to operate the upper and lower limit
switches respectively.
Alignment
The alignment procedure is quite
simple since the transmitter is already
aligned to 304MHz. You will need to
make up the test circuit shown in
Fig.6 . Connect it to test point TP1 on
the receiver/decoder board. Press the
.0033
TO TP1 - - - I I I - ~ . . - - - - - - ,
D1
OA90
GND1i------'
.,.
Fig.6: this little RF detector circuit is
connected to test point TPl on the
receiver board for the alignment
procedure. You simply press the
transmitter button & adjust CVl on
the receiver for a maximum reading.
HEAVY DUTY TV/SPEAKER
WALL-CEILING BRACKETS
The M83 and MB5 are
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mounting brackets
designed for securing
small TV's and speakers
to walls, ceilings, desks or
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mounted both units can
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as well as being swivelled
up or down to any viewing
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metal platforms have
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mounting and are easily
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key supplied with the unit.
Imported and distributed by:
.ABISTI\
ELECTRONICS
Available through the following retailers:
David J Reid
All Electronic
Electronics.
Components.
127 York Street.
118 Lonsdale St.
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Melbourne. 3000.
NSW. (02) 267-1385.
Vic. (03) 662 3506.
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• Enhances Video and Audio Signals.
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This photo shows the motor drive arrangements on a roller door. The upper
limit switch can be clearly seen.
transmitter button and adjust trimmer capacitor CVl for the maximum
possible DC voltage reading on your
analog multimeter.
As a point of interest, the prototype
gave a range of over 200 metres with
the antenna wire attached.
Our prototype was installed in a
large plastic case with a clear plastic
lens on the top for the 12V garage
light, switched by relay RLA5.
Power supply details
Inside the case is a standard multi-
tap transformer (Altronics M-6672)
with the 12V windings connected to
the rectifier inputs on the board. Also
installed is a 12V 6.5A/h sealed lead
acid battery. This is connected as
shown in the wiring diagram ofFig.4.
This is trickle charged via an 82Q 1W
resistor and it delivers power to the
circuit and to the motor via a 1N5404
silicon rectifier diode.
By using this power arrangement,
the circuit will work all the time regardless of whether mains power is
present or not - you still want to get
The AVE SSL is easily installed and
provides excellent results .
11111
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Please send me _ _(Qty) AVE SSL video I
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I dubbing/enhancing
My cheque/money order or credit card de· I
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APRIL 1991
33
A typical motor drive arrangement for a Tiltador. A length of 1-inch water pipe
serves as a carrier for the linkage for the door and it is driven back and forth by
the bicycle chain.
Here is a closeup view of the main
drive gear on the roller door. This one
has been welded but there is no
reason why it could not have been
attached with bolts and spacers to the
inner frame of the door.
This is a commercial installation on a panel lift door but the principle of
operation is very much the same as the Tiltador example. The main spring is
part of the original door mechanism.
into your garage during a blackout.
Using the battery also means that the
transformer really only has to trickle
charge the battery, not drive the motor directly.
Installation details
The actual installation will depend
on your type of door. To give you a
good idea of how it can be done, we'll
let the photos included with this ar34
SILICON CHIP
tide do the talking. All are based on
chain drive using readily available
bicycle sprockets.
Some of the brackets used in the
photos have been welded but there is
no reason why you can't use all bolted
construction or brackets made of timber, provided they are strong enough.
Once you have your installation
complete and working, you will need
to ensure that the top and bottom
limit switches do work as desired and
that the over-current trip circuit is
adjusted. To set the over-current adjustment, place an obstruction such
as a cardboard carton underneath the
door. Set the lower · limit adjustment
VR2 so that the descending door does
not crush the carton but does not tend
to stall when starting.
To set the upper limit adjustment,
get someone to hang onto the door to
give it some extra load. Again, set the
adjustment (VRl) so that the door ·
does not stall when starting but will
stop when given an extra load.
Finally, note that there are a few
changes to the receiver circuit which
have been incorporated into the final
PC board layout of Fig.4. First, the
lkQ resistor connected to one end of
choke RFCl is now 2.2kQ and extra
bypassing components (a 4.7kQ resistor and lOµF capacitor) are now
incorporated into the supply line for
Ql. Second, pin 12 of ICla is connected directly to ground and the
lOMQ resistor is deleted. And third,
the pin numbers for IClc and ICld on
the receiver circuit are actually
swapped on the board layout.
SC
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both hard and floppy drives as well as power connectors for the motherboard. Has full
short circuit and overload voltage protection. Dimensions 225mm x 140mm x 120mm.
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* All prices include sales tax.
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Due to Technical advances, products we supply may in
some cases vary from those pictured. In all cases the
products supplied are guaranteed to perform to an equal
or higher standard than those pictured
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·--------------------------·
VINTAGE RADIO
By JOHN HILL
Converting an Airzone to AGC
Although automatic gain control (AGC) became
common in receivers from the early 1930s on, ·
there were a number of sets made at around
that time which lacked this useful refinement.
This month, we look at how a 1937 Airzone
receiver was fitted with AGC.
It was one of those things that I had
been meaning to do for some time. In
my collection of old radios, there is a
rather stately looking Airzone - a 1937
console model which has no AGC.
Just why it lacks AGC is a bit of a
mystery, for nearly all radios of that
era were fitted with this feature .
At one stage, I suspected that an
This is the 5-valve Airzone that was
converted to AGC. It is a 1937 console
model with a 10-inch electrodynamic
loudspeaker. Adding AGC makes it a
far more pleasant set to use.
36
SILICON CHIP
AGC circuit must have been lurking
in there somewhere but had become
inoperative. However, a close inspection of the chassis (as best as one
could without a circuit diagram) soon
confirmed that the set had never had
AGC. There were two reasons for this
.conclusion:
(1). the receiver had no valves which
contained diodes; and
(2). the volume control was a wire-
wound potentiometer in the cathode
circuits of the frequency converter and
IF amplifier valves.
Clearly, the set was never designed
for AGC.
The valve complement (confirmed
by a sticker inside the cabinet) is as
follows: 5Y3, 6A8, 6U7, 6J7 and 6F6 .
This is a fairly standard. layout for ·a
1937 5-valve receiver, with the exception of the 6J7. Most sets of that
vintage would use a 6B6 or a 6B8
instead. Both these valves contain
diodes which would have made AGC
easy to implement.
Valves with diodes
As explained in last month's column, there was a change in superhet
design in the early 1930s, when valves
containing diodes were first intro-
The Airzone chassis. The valve complement is as follows: 5Y3, 6A8, 6U7, 6J7
and 6F6. This is a fairly standard line-up for a receiver of that era with the
exception of the 6J7 (most sets would have used a 6B6 or 6B8).
duced. These diodes could be used
for both an improved form of detection (diode detection) and a more
practical form of AGC than any previous attempts. Along with these
changes came a change in volume
control methods. The volume control
was moved from the cathode circuit
of the IF valve(s) and, in some cases,
the frequency converter as well, to
the control grid of the first audio
valve.
An AGC circuit rectifies the received signal and produces a negative voltage which is directed back to
the grids of the IF and converter
valves, to control their gain. Strong
signals increase the AGC voltage,
which reduces the gain, whereas weak
signals have the opposite effect.
As AGC circuits work with variable mu valves, there was little reason why the old Airzone could not be
converted to ACC. Both the frequency
converter and the IF amplifier valve
were common types, as used in con. junction with AGC in other receivers.
All that was needed was to add a
couple of diodes and a few other bits
and pieces.
Conversion options
There were a number of ways to
approach the diode problem. First, a
different first audio valve such as a
6B6 or a 6B8 could be fitted, which
would have a pair of diodes in the
same envelope. Another possibility
was to fit a separate twin diode valve,
thus retaining the existing 6J7 as the
first audio valve. As a last resort, a
couple of modern solid state signal
diodes would do the job just as well
as any thermionic type - do I sense
some readers throwing up their hands
in horror?
In any case, if the 6J7 is to be used
as a straight audio amplifier, rather
than a detector, its operating conditions should be changed. As a detector - almost certainly an anode bend
detector - it would be biased close to
cut-off, using a high value cathode
resistor and, possibly, a low screen
voltage. This would restict its operation as an amplifier.
In 'the end, I decided to install a
6H6 twin diode valve. One reason for
this decision was the fact that the
chassis already had provision for an
additional valve. Fitting the 6H6 was
as easy as removing a cover plate and
bolting in a new socket. The heater
The 6H6 twin diode was made in both metal & glass envelope versions. At least
the glass version looks like a real valve, even if it is rather small.
pins of the 6H6 socket were wired to
the heater pins of a nearby valve.
An AGC circuit was required and
the one shown in Fig.1 was taken
from an old radio book. There are
some variations in AGC circuits (eg,
simple AGC and delayed AGC - see
last month's story), and some look far
more complex than others. The circuit used requires only one diode and
so the 6H6 anodes and cathodes were
connected in parallel to form a single
unit.
The next step was to fit a new volume control. A 500kQ carbon pot was
installed in place of the old wirewound pot. However, although the
old control was removed from the
chassis, it was left connected in circuit. Mere about that later.
AGC-----,
The new volume control was wired
in accordance with Fig.1, with the
wiper arm going to the 6J7 via an
existing .01µF capacitor. Also added
were the various resistors and capacitors needed for the AGC circuit, plus
the h eater wiring for the 6H6. The
circuit also shows the changes made
to the 6J7 circuit. This . left only the
two AGC outlets to be connected.
These two AGC lines had to be
connected to the control grids of the
first two valves, via the first IF transformer's secondary winding in one
instance, and the aerial coil secondary winding in the other. However,
it was not just a matter of connecting
the AGC lines to existing connections,
because they were both connected to
chassis.
0
-----1---HT
1.5MI
1M
.01
1M'
.,.
Fig.1: the AGC circuit produces a negative voltage and this is applied to
the grids of the first two valves, via the aerial coil secondary winding in
one instance & the first IF transformer secondary winding in the other.
APRIL 1991
37
Only a handful of components was required to convert the old Airzone to AGC.
The 6H6 twin diode was chosen so that the original 6J7 first audio valve could
be retained but other approaches should prove equally viable (see text).
•
•
The 6H6 twin diode valve was easily fitted to an existing valve socket hole in
the chassis of the old Airzone.
These connections need to be carefully traced back from the valve grids
and unsoldered from the chassis, so
that the AGC lines can be connected
to them. After the AGC lines were
connected to the coil terminations,
these points were bypassed to chassis
via O. lµF capacitors. At this stage
everything was ready for a trial run.
Initial results
The initial results were a bit disappointing. The AGC additions had
thrown the front end of the receiver
considerably out of whack. Motor38
SILICON CHIP
boating, whistles and howls indicated
that all was not well and there was a
brief moment when I reflected on the
wisdom of drawing up the original
circuit in case the set had to be returned to "as it was" condition.
At this stage I was glad that I had
left the original volume control in
circuit. It was, in fact, nothing more
than a variable resistor in the cathode
circuits of the first two valves, and
capable of providing variable cathode bias for them.
That was all that was needed to
correct the instability. After finding a
position where everything worked
reasonably well, the potentiometer
resistance was measured and a fixed
resistor fitted in its place.
The set was greatly improved by
the AGC conversion but I was still a
little disappointed regarding its effectiveness. Strong stations were still
fairly strong, while weak stations were
still inclined to be weak.
Out came the single substitute cathode resistor and in went two 5kQ pots;
one in the frequency converter cathode and the other in the IF amplifier
cathode.
With the set tuned to the noise between stations (virtually no signal),
the volume level could be brought up
quite noticeably by fiddling with each
cathode resistor. After replacing these
pots with fixed resistors the AGC was
more effective (Note: the cathode resistance was determined simply by
setting the pots for maximum volume
without instability). These adjustments made a significant difference
to distant stations but seemed to have
had little or no affect on close stations.
One noticeable change with the
AGC conversion was that the receiver
needed retuning. This was particularly evident with the first IF transformer, which had its secondary circuit upset by the addition of the AGC
line. A complete re-alignment of the
receiver was in order and, while it
was not badly out, there were noticeable improvements when the job was
finished .
The conversion turned out to be
quite successful and I love the old
Airzone even more than before.
Other conversions
Flushed with success I decided to
convert another 1937 set, a console
model Playola. Although fitted with
a 6B6 and using diode detection, the
receiver had no AGC, which seemed
a bit cheap and nasty to me. It too
responded well to the conversion and
is now a far more pleasant set to use.
The third and last radio to be converted (a 1934 model Commodore)
was a little different. It uses a 57 as an
autodyne frequency changer, followed
by a 58 IF amplifier, and has no diodes. In this instance, a germanium
signal diode was used, with only one
valve, the 58 IF amplifier, being AGC
controlled. (The old 58 was one of the
first variable mu tubes to be made).
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Radio
Vintage Wireless
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Repairs - Restoration - Sales
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This temporary test rig shows that the AGC circuit produces a negative voltage
(the larger the signal, the higher the voltage). This negative bias is directed to
the grids of the pre-detector valves.
The frequency changer was not
suitable for AGC control for two reasons: (1) the 57 is not a variable mu
tube; and (2), an autodyn e freque ncy
changer is notoriously cranky (even a
minor change in operating conditions
can cause it to stop oscillating).
The old Commodore responded
fairly well to the treatment, considering that AGC is applied to only one
valve. It certainly is a big improvement on no AGC at all.
Converting a receiver to AGC can
easily introduce other problems because the circuit has been interfered
w ith. Th ere may be other methods of
solving th e problems I encountered,
but th e sets I converted all work well,
an d that's what matters most.
Altogether, these three AGC modifications took quite a bit of time to do,
but they were worth both the time
an d effort. It was an interesting project and the addition of AGC made all
th ese receivers far more pleasant to
operate.
SC
Parts are available for the enthusiasts
including over 900 valve typ es, high voltage
capacitors, transformers, dial glasses,
knobs, grille cloth etc.
Circuit diagrams for most Australian makes
and models.
Send SAE for our catalogue.
WANTED - Valves, Radios , etc.
purchased for CASH
Call in to our Showroom at:
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ELECTRONICS
Avsllsbte through the following retailers:
This simple AGC conversion module was built up on tagstrip & fitted to a 1934
model Commodore receiver. In this case, a germanium signal diode was used,
with only one valve, the 58 IF amplifier, being AGC controlled. The tagstrip
method makes the conversion a bit neater than the more usual point-to-point
wiring method.
B ernys.
Bridgepoint.
Military Road.
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NSW. (02) 969 1966.
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56 Renver Rd.
Clayton.
Victoria. 3168.
(03) 543 2166.
A PRIL 1991
39
SERVICEMAN'S LOG
Mystery, mystery & frustration
This month, I have three short stories, two of
which introduce an element of mystery and
the third a sense of frustration. It is unlikely
that we will ever know the answers to the
mysteries but the cures were obvious.
The first story concerns a Toshiba
48cm colour TV set, model C-2020.
As is often the case, the customer's
complaint over the phone was rather
vague. His first statement was to the
effect that "it keeps going off", but
further remarks suggested that the
"off" was poor performance rather
than total failure. And the "keeps
going" suggested it was probably
intermittent. Anyway, I suggested he
bring it in for closer inspection.
So he duly turned up and I set it up
while he was there. The picture was
faint and lacking contrast. I forced it
up to a more recognisable level with
the brightness control and
was then able to see that it
was riddled with hum. The
vertical:; were weaving back
and forth and it was also displaying hum bars.
Well, it looked like a snack.
It was obviously a power supply fault
and this was a power supply with
which I was very familiar. I mentally
registered that it was almost certainly
the main filter capacitor, C810, a
680µF electrolytic (top of Fig.1). I'd
seen the symptoms many times before .
At the first opportunity, I pulled
the back off and checked the HT rail.
This should be about 110V but was
only 86V, measured at the emitter of
the regulator (Q801). On the other
hand, the collector was at 133V which
is almost spot on. This raised some
doubt about the capacitor but per-
haps not as much as it should have.
Anyway, I rustled through my
stocks for a replacement. As it happened, I didn't have an exact replacement but I did find one that would
do, but which would need some extra
work to fit.
By now I wasn't so sure about the
capacitor and, with the need to do
this extra work, I was less inclined to
rush in. I tacked a couple of leads
onto the capacitor, then patched it
into circuit across the suspect unit. It
had no effect whatsoever.
So much for my original "snack"
diagnosis; it was time to stop guessing and start working. The circuit is
not particularly complex and is quite
conventional. There are three transistors: Q803, error detector (bottom of
diagram); Q802, regulator driver
(above it); and Q801, which is the
main regulator (top of diagram). The
other major component is the bridge
rectifier, consisting of diodes D801,
D802, D803 and D804.
I went immediately to the voltage
adjustment control, R851, a 1.5kQ
variable resistor in the base circuit of
the error amplifier. This sets the HT
rail to the required voltage but I wasn't
really surprised that adjusting it had
no effect.
Next I made a preliminary check of
those minor components most likely
to have upset the regulator action and,
while I couldn't be absolutely certain, all the indications were that
these were OK.
Which transistor?
So that left the transistors. Both the
error amplifier (Q803) and the regulator driver (Q802) have given trouble
in the past, with the symptoms ranging from the simple to the weird. The
regulator transistor can fail just as
readily as the other two, but it is normally a catastrophic failure; breakdown between emitter and collector,
creating an excessive HT rail voltage
(typically around 135V) and causing
40
SILICON CHIP
C+)f2y)
QBOI
2SCI 195 FA-I
POWER REGU,
GRN
I
L1
~C809
R_~ii(G)
USOI
D813
-
3,3)1
(160V
L901
1S1942
APF SWITCH
TSB-2056<2055>
DEGAUSSING COIL
POWE_R_B_OA_R_D~PW~-~,,~10._.
Fig.1: the power supply circuit for the Toshiba C-2020. Q801 is the regulator
transistor, Q802 the driver transistor, and Q803 the error amplifier.
the set's protective circuits to shut it
down.
So where should I start testing?
Murphy's Law states that whenever a
faulty component is one of a string, it
will always be at the end opposite to
that at which one starts. And if one
attempts to minimise this effect by
starting in the middle, it will always
be at the far end of the last leg
checked.
But I had to start somewhere and,
Murphy aside, I had a funny feeling
that this time it was the regulator transistor (don't ask me why). So I disconnected the base and emitter leads
and made a simple ohmmeter check
in the time honoured fashion.
This failed to reveal anything amiss,
even when I went looking for leakage.
Nevertheless, the funny feeling persisted and, with the leads disconnected, it was just as easy to try a
replacement. I didn't have the exact
replacement (2SC1195) but I found a
BU126 which is an acceptable substitute.
It took only a few minutes to fit it
and - presto! - that was it; a normal
picture and no hum problems. All
that was needed was a marginal adjustment of R861 to bring the HT rail
down a few volts.
I ran the set for the rest of the day,
with no sign of trouble, than rang my
customer with the good news. As
stated earlier, there was a hint of intermittency in the customer's original
complaint but there was no sign of it
on my bench. In any case, subsequent
follow-ups confirmed that all was
well.
Transistor checks?
But I was still puzzled as to what
was wrong with the transistor.
Granted, the simple checks I made
are not always conclusive and, for
this reason, I use a curve tracer as a
back-up in sticky situations.
So I hooked the tracer up to the
CRO, set it up for power transistor
checking, and tried the transistor. And
it traced out a virtually perfect curve.
So, was it breaking down - or something - at the higher voltages in the
set?
It is possible to vary the operating
conditions of this equipment to a
limited extent, so I adjusted the settings to increase the base current and
also to increase the collector sweep
voltage, within these limits.
But there was still no sign of a fault.
I left it running like that for an hour
or so, at the end of which time the
transistor was quite hot; I could touch
it briefly but it was too hot to hold.
And still a perfect curve. However,
this involves only relatively low voltages; not more than 30V on the collector.
And that's about as far as I can go. I
still think the most likely explanation involves the higher operating
voltages which I cannot duplicate. But
now, having made these checks, I
would dearly like the chance to put it
back in the set, or another one like it.
This is out of the question at the
moment but I'm keeping it handy,
should the opportunity arise.
So for now, the mystery remains.
A record for rarity
The next story also poses a mystery
but of a completely different kind.
And it must surely set some kind of a
record for rarity; I'd be prepared to
bet long odds that no one has ever
encountered it before. Rash words?
Well, see what you think.
The culprit was a Mitsubishi model
CT-2963 68cm colour TV set. It was
brand new, straight out of the carton
at my local retailer colleague's shop.
It is an upmarket model which, in
addition to the large screen, boasts a
flat, square picture tube.
An intriguing aspect of the set was
that it was made in Scotland. A Mitsubishi TV set made in Scotland! it's almost a contradiction in terms.
Perhaps these sets should be renamed
Macsubishi?
All right, so I digress. Now to business. My colleague had unpacked the
set, to put it on display, when a preliminary check indicated that all was
not well. So he brought it around to
me, complaining that "it's got hum
on the picture".
The model was new to me, apart
from showroom acquaintance, and I
APRIL 1991
41
SERVICEMAN'S LOG - CTD
.,~9,... _
~ ..... A. N\\-r"SOS\SHl
-rv se..-r
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N'A"DE- IN ~-n.ANT)f
had no data on it. So my first reaction
was that I would have to obtain a
manual. But I thought I might as well
have a look at it anyway, just to confirm my colleague's symptoms.
So I unpacked it and set it up. And
as luck would have it, it was switched
to SBS which was running a test pattern; I couldn't have wished for a better demonstration of the fault .
On the other hand, describing the
fault is not easy, so please bear with
me. Those familiar with SBS will
know that, superimposed on the test
card itself, are two running displays,
one near the top , carrying program
data and channel data, and one near
the bottom of the picture, carrying
the title and other data on the music
being played.
And it was the bottom display
which exhibited the fault. The message comes in from the right and this
was quite normal for the first few
centimetres, until it reached the first
vertical colour bar; green at the top
and blue at the bottom. Here it kicked
upwards for about 15cm, then ran
downhill towards the centre of the
screen, where there is a short red colour bar.
From here it ran uphill and traced
what was virtually a mirror image to
42
SILICON CHIP
the left hand side of the screen; up to
the magenta bar, a short downward
kick, then straight out the left.
Any ideas? Forget it; you'd never
guess it in a month of Sundays .
Shock, horror
My own reaction was one of bewildered shock. I could understand why
my colleague had described it as hum.
He is familiar with the classic hula
girl pattern caused by hum in the
horizontal system and, with his limited technical knowledge, assumed
something similar in the vertical system.
And, while I ruled out hum, I went
through the mental exercise of trying
to visualise what kind of vertical
waveform distortion could cause such
an effect. After a couple of tries, I
gave up; the brain simply refused to
cope.
I let the set run while I went on
with a couple of other jobs, hoping
for inspiration. None was forthcoming - at least not directly. But while
working on other sets, I had been
made more aware of the difference in
picture tube faceplate curvature, between the old tubes and the new.
When I went back to the Mitsubishi, I idly ran my hand over the
tube, mentally assessing the curvature - just to reassure myself that it
was not truly flat. It was not of course
- it was significantly convex, just as I
knew it would be.
At least most of it was. When I ran
my hand across the bottom of the tube
I suddenly realised that a particular
area (need I say where) was not convex but concave, with about the same
order of curvature as 'the convex area.
So that was it; it wasn't an electronic fault at all, it was an optical
effect caused by a distorted picture
tube faceplate. And that was the end
of the exercise as far as I was concerned; the set was going straight back
to Mitsubishi. The warranty payment
for changing a picture tube is not
exactly generous and their service
department can do the job cheaper
than I can.
But my main reaction was that I
wanted the thing out of my workshop
as quickly as possible. Maybe I was
over reacting but I felt sure that any
tube with a distorted faceplate - and
certainly one as bad as this one - was
a prime candidate for spontaneous
implosion. (I've seen the result of an
implosion and it isn't funny).
I don't know much about the glass
technology of picture tube design but
I do know that the curvature is a vital
factor in tube strengtp.. And I understand that the so-called '"flat" tubes
have only been made possible by
modern computer design techniques,
which have been able reduce the curvature significantly while retaining an
acceptable safety margin.
That, in my language, means that
they have pushed the design about as
far as they dare. Not that there is anything wrong with that in itself, but
does it allow for the kind of distortion I found in this tube?
More to the point, how did this
tube ever get into the field? How did
it pass the tube manufacturer's inspection and how did it pass the set
manufacturer's inspection?
The drifting Tandy
My next story concerns a Tandy
48cm colour TV set, a CTV-2001. It's
not a very profound story technically
but it does emphasise some of the
day-to-day problems and traps one
encounters.
One problem was to get a clear history of the fault, which came in dribs
and drabs. The set came to me from a
local Tandy dealer, who had sold it to
one of his customers. It was a new set
and still under warranty. The customer's complaint was that it "drifted"
off channel after running for some
time.
Fortunately, I have a colleague - a
fellow serviceman - who works for
another Tandy outlet several suburbs
away. The local Tandy dealer had
approached him first , since he had
the service facilities, but had been redirected to m e.
The main reason for this was the
distance involved. Everyone is anxious to avoid transport costs these
days, so my colleague suggested th at
I could handle the job.
The warranty situation did not present any problem, even though I do
not normally handle these sets on this
basis. The plan was for the Tandy
dealer to pay me normal rates, then
straighten this out between the two
. Tandy outlets.
That was about as much information as I had when the set came to me
and so I immediately rang my colleague, first to confirm the arrangement and second to find out what I
could about this particular model. I
Mitsubishi/AWA AV10
Symptom: no sound or picture.
All mechanical functions are normal and the machine will record
normally for playback on another
VCR. Playback audio and video
are present at the NV output sockets but not via the RF out.
Cure: RF modulator unserviceable. The usual procedure is to
replace the modulator at considerable cost. However, replacing
the TA7673 IC in the modulator is
worth a try. The chip is cheap and
has cured the problem on at least
one occasion .
TETIA TV Tip is supplied by the
Tasmanian branch of The Electronic Technicians' Institute of
Australia. Contact Jim Lawler, 16
Adina St, Geilston Bay, 7015.
didn't even have a circuit.
The business side of things was
quickly confirmed and we moved on
to techicalities. On the basis of the
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Built-in Meter to check EHT transformers
including split diode type, yokes and drive
transformers.
$78.00 + $3.00 p&p
.HI-VOLTAGE PROBE
Built-in meter reads positive or negative 050kV. For check ing EHT and focus as well as
any other Hi-tension voltages.
$98.00 + $5.00 p&p
LOW VOLTAGE PROBE
Ideal for checking microwave ovens and
TVs. The ranges are from 0 to 5kV Negative
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$94 .oo
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symptom:,, my colleague suggested
that I look immediately at the tuner
control board. Though these sets are
very well made in most respects - a
fact that I confirmed later - they appear to have one weakness.
To understand this it is necessary
to jump ahead a little and describe
the layout of the set. The main board
is about 25cm square and sits in the
bottom of the cabinet, mounted in a
reasonably substantial moulded plastic frame to give it additional strength.
The whole assembly is held by four
screws, one at each corner.
This plastic frame also serves to
support the tuner control board which
is a narrow board, about as long as
the main board is wide. This is
mounted vertically on the main board
at the fron_t of the cabinet, in a vertical section of the moulded plastic
frame. The top edge of the control
board sits just below the bottom of
the picture tube. This board carries
the tuner programming ICs and all
the front panel controls. The tuner
itself is mounted on the rear of the
main board, allowing the antenna
coax to connect directly to it.
So what was the weakness? Accord-
TETIA TV TIP
PO Box 1174
Gosford Sth, 2250
• Freight chartge on normal size Items $10.00. Monttors etc. $15.00.
• lnsurnce charge is 1% of total order value.
PRICES VALID FOR THE MONTH OF PUBLICATION OR WHILE STOCKS LAST
+
$5 .oo p&p
DEGAUSSING WAND
7,700 apere turns. Strong magnetic field, larger
than usual coil with multicore centre. Double
insulated for safety with momentary on/off switch.
240V A/C 2.2 amps.
$75.
This one is just about as important as having a
soldering iron in your toolbox'
. 0 p&p
r'_:. . . . . .,
REMOTE CONTROL TESTER
~ ,
r'\'\
" ,. '.J;y
$85.00 + $4.00 p&p
TUNER REPAIRS
(INFARED OR ULTRASONIC)
Designed to test any lnfared or Ultrasonic
control units. With the extension lead you can
also test infared units which cannot be placed in
front of the testing unit. Requires a 9V battery .
Output is via the LED diode and piezo speaker.
from only $11.00 + p&p
Chekque,dMonMey Order,d
8 an ea~ or asterca~
TIJNERS[\216 Canterbury Road, Revesby,
~
NSW, 2212, Australia
Telephone (02) 774 1154
We also repair most tuners on an exchange basis.
TV
1'• •
APRIL 1991
43
SERVICEMAN'S LOG - CTD
ing to my colleague, it was the "just
below" which wasn't "below" enough
- if you follow me. In other words, the
tuner board was too close to the bottom of the picture tube.
And the end result was that, if the
set received a moderately severe jolt,
as in transit, the board and picture
tube could come into contact with
enough force to crack the board or, at
least, some of the tracks on the board.
It had happened on a number of occasions and was now the first thing to
be checked whenever any tuning
problems were ,encountered. Hence
his advice to check this board.
Which brings us to the point where
I had the set on the bench and was
ready to turn it on and see what happened. The first surprise was that
, there appeared to be no channels
programmed into the tuner. Initially,
I wondered whethe:r this was a manifestation of the drift problem but, fortunately, I had occasion to talk to my
colleague again before I acted on this
thought. It was then that I learned
that the set had only ever been used
with a video recorder. In fact, it was
used in a coffee shop/milk bar to play
video clips for the entertainment of
its teenage patrons. So it had only
been programmed for channel 1.
Since it was easier to use off-air
signals, I set to and programmed the
tuner for the local VHF channels, plus
SES on the UHF channel. Then I
switched it to channel 2 and let it
run. It ran like this for some hours,
with no sign of trouble, which didn't
seem to tally with the description of
the fault - at least in terms of time.
·So I turned to the pattern generator,
set it to channel 1, and fed the signal
into the set. And that did get results;
in a very short time, the signal started
to drift. This was a bit puzzling, so I
repeated the test on some of the high
band VHF channels and also on the
UHF channel. They were all rock
steady.
By now I was having definite second thoughts about the cracked board
theory; the selective nature of the fault
suggested an internal tuner fault. But,
in any case, the board had to come
out for inspection; if there was a
"funny" due to damage and I missed
it after being warned, I'd never hear
the end of it.
I pulled the back off the set and
then, on impulse, tried another tack. I
ran the set on all channels in turn, at
the same time applying pressure and
a twisting action to the tuner.
None of this had any effect until I
reached channel 1, whereupon it responded immediately; by applying
the twisting action in the right direction and with the right pressure, I
could virtually tune the signal in or
out. This was even more evidence to
support the faulty tuner theory.
But I still had to clear up any suspicion of a cracked board. I pulled the
board assembly out, unscrewed the
control board from its frame - to get it
in a good light - and went over it
carefully, using a jeweller's loupe.
After much searching, I was forced to
the conclusion that there were no
cracked or damaged tracks. While it
was thoughtful of my colleague to
warn me - and I'm passing the warning on - it was not the problem this
time.
.1.m.,.;. r.:.1;i:.11:
RCS Radio Pty Ltd is the only company which
manufactures and sells every PCB & front panel
published in SILICON CHIP, ETI and EA.
651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491.
44
SILICON CHIP
So back to the tuner. I turned the
main board over and examined the
various soldered connections to the
tuner pins, again with the jeweller's
loupe. I could find nothing wrong. I
then set up a meter to monitor the
tuning voltage but again drew a blank;
it was perfectly steady.
Finally, more or less in deperation,
I went over the soldered connections
and remade each one. It was more to
be able to say that I had done it than
any real hope that it would effect a
cure. Imagine my surprise, therefore ,
when I set everything going again and
found that the fault had vanished.
None ofmy previous tricks to bring it
on had any effect.
So what had I done? Had there been
a faulty joint which was not visible?
Perhaps, but I was not convinced. The
whole setup just didn't jell. I couldn't
reconcile the channel selective nature of the fault with a faulty joint.
Nevertheless, the set ran for the rest
of that day without missing a beat, in
spite of all the twisting, pressing and
bashing I could dish out.
Murphy's little joke
So I finished up with a conflict of
ideas. The more emotional line of
thought wanted to believe that the
fault was fixed; the commonsense line
told me that such a cure just wasn't
on. It was all one of Murphy's horrible jokes.
But the set ran all the next day and
all the following day. By this stage, I
was about to send it back to the customer but then, on the fourth day,
there was the fault, exactly as before.
It was a narrow squeak.
More to the point, I had no doubts
now that it was an internal tuner fault.
And that meant a new tuner, which
seemed simple enough until we tried
- and by "we" I mean the Tandy personnel as well as myself. The final
answer was: "On back order; delivery
date uncertain."
I didn't go into the finer details of
this situation, or who or what was to
blame. Suffice it to say that there
seemed to have been a miscalculation somewhere. But that's not unusual.
So the set is sitting in a corner of
my bench, waiting until a tuner becomes available. In the meantime, I
have left it to the Tandy dealer to
make peace with his customer. It's all
very frustrating.
SC
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Ref: SI II con Chip Aprll 1991
T~ls kit ls a4
channel tight
chaser. Each
channel will hardle
up lo a36W globe.
Dress up your car,
truck, etc. A novel
approach for a brake
warning light? Kit
Includes PC board
and components.
No globes supplied.
Cal. KC-5092
RAILMASTER TRAIN
ONTROLLER
Ref: SIiicon ChlpAprll 1991
Had enough of Iha! silly whine
coming out of your HO-scale
'38' loco? This steam sound
simulator makes arealistic
ELEC fRC' } 'chufflng' sound Iha! keeps
bLECTRC' ( pace with the loco speed.
ELEClRC' i:
Kil Includes PC board all
specified components and the
ELECTRC' ) expensive 82mm loudspeaker.
ELECTRC /
Cal. KC-5093
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:i
KA-1730
$21 95
:i Rall master Train Controller
29
Re/Sponse SPEAKERS
kll Cat. KC-5028 $89. See
catalogue for full delalls.
Super high power dual impedance 4 and an.
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0 SERIES 11
REAMP KIT
$2495
)
6" 80Wrmsca1. cw-2140
r· SOLAR n• NELS
$75
,R ELECTRO!
\R ELECTRO! ,
rM
\R ELECIROI • Brand new range for 1991, al much lower prices - or much
\R ELECTRO! : higher watts per dollar. Available soon.
\R ELECTRO! • Specifications:
\R ELECTRO! :
1watt
4watt
8watt
\R ELECTRO! •
13-18V
6-SV
13-18V
\R ELECTRO! • Operating V
\R ELECTRO! : Operating A
120/160mA 200/280mA 500mA
\ R ELECTRO! • *Power W(peak) .75/1.25
2.5/5
8W
\R ELECTRO! :
305x610
Size mm
152x152
305x305
\R ELECTRO! :
-5o•c to +70°C
\R ELECTRO! : Temp Range
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\A ELECTRO! :
cat ZM-9020
\R ELECTRO! •
IR El f'CTROI : cat ZM-9026
IR ELECTRO! :
cat ZM-9030
\R ELECTRO! :
\A ELECTHOI :
\ R ELEClHOI •
\R ELECTHOI :
\R EU:CTROI •
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\R ELECTRO; :
IR ELECl R01 •
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8" 120Wrms Cat. CW-2142
$109
1 0" 160Wrms Cat. CW-2143
/60 STEREO AMP
IT
$165
12" 200Wrms Cat. CW-2145
KA-1652
$199
Dome midrange (Bo
$24H 1 watt 6V
$89H 4 watt 12V
$169H 8 watt 12V
Cat. C M-2090
69
only)
$49"
Dome tweeter (so only)
Cat. CT-2010
$3250
CR2025 as used In our Dalabank
Cat. SB-2520
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ELECTROt
ELECTRor
ELECTR01
ELECTRO!
$3.50 ea
PC BOARDS VERO
STRIP TYPE
Alpha numeric grid, pre-drilled 0.9mm, 2.5mm
spacing.
SOLAR GENERATOR
KIT
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ELECTRONICS
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JAYCAR
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ELEClRONICS
We have purchased alarge quanllly of DPDT 1'N 3A high
qualily Japanese made Omron PC mount relays. These are
Telecom approved, plastic sealed with bifurcated crossbar
contacts. They conformlo International 2.54mm terminal
pitch and have alife expectancy of 100,000,000 operations.
You would expect lo pay around $10 each for these. . _
Specifications:
·- ------=
Voltage
DC 1'N
Current
24mA
Resistance soon
Contac1Raling3A
Cal. SY-4055
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JAYCAR
JAYCAA
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$2SO
$3 79
95 X 303mm Cat. HP-9544 $5 ..
95 X 76mm Cat. HP-9540
))
Ref: ETI December 1987
Acheap, no fuss way lo trickle charge a 12V lead acid/deep
cycle or Gel baltel}' from any of the solar panels shown
above. The lype of panel used Is nol vel}' critical. Typically
no more power than 6 walls is required with an oulpul
voltage of 12-18 volts. Short form kit Includes PCB and all
components.
Cal. KE-4730
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$3.50 ea
CR2032 Cal. SB-2522
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95 X 152mm Cat. HP-9542
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Considering ihe price, we are most impressed at how well this unit works. II h~s an ABS plastic body wllh strong suction. Unll is
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very
easily
cleaned,
corni
ng
apart
In
the
centre,
In
moments.
Spare
lips
are
available
and
are
very
reasonably
priced.
Tola!
ienglh
Here's whal you gel:
ICS JAYCAR
Inc. lip 195mm.
• 5 slolled blls 0-1 , 3-4, 5-6, 8-10, 12
ICS JAYCAR
Repl acernenl lip (Tetlon;cat. ___
hex bils 3/32', 5/64', 7/64', 1/8', 9/64'
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• 4 Philips bils No. 0, 1, 2 & 3
Cal.
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And ll's all housed In a sealable lough pl astic case .
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Replaces !hose old desk type calendars. Electronic
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Large easy lo read display wilh
Incorporates a large 18mm high display for
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temperature from -20°C to +70°C. And a l the
and 3 year ballery life, Ideal
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tough of a button the time appears . There are
for desks, cars, kitchens, etc.
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two temperature sensors - one inside the unit
<at>
CS JAYCAR
Cal. OM-7218
and the other on the end of 3.5 metres of
CS JAYCAR
95
cable for reading outside. Flick a switch and it
CS JAYCAR
will read the temperature instantly for eithert
CS JAYCAR
CS JAYCAR
inside or outside
CS JAYCAR
Cat. XC-0125
CS JAYCAR
CS JAYCAR
CS JAYCAR
CS JAYCAR
CS JAYCAR
CS JAYCAR
CS JA,YCAR
CS JAYCAR
CS JAYCAR
CS JAYCAR
The Maggylarnp Is awidely adjusled
CS JAYCAA
magnifier wi th a12.7cm diarneier biCS JAYCAA
convex lens 4.00 dioptres focal lenglh of
CS JAYCAA
25.4cm. II ls essenlially a rnl nlscope wllh
CS JAYCAA
llghling. Maggylarnp has flexible arms for
CS JAYCAA
CS JAYCAR
easy posilioning. Handsome, slurdy
CS JAYCAR
conslruclion assures years of service.
CS JAYCAF
CS JAYCAF
Now you can have lhe same beaulilui 'firelly' lighting Iha! Is
CS JAYCAF
CS JAYCAF
all over !he civic squares around Auslralla and overseas.
CS JAYCAF
Now you can purchase the bulbs In packs ol 10 for only
CS JAYCAF
Ferguson
brand.
Supplied
cornplele
in
a
sealed
case
wilh
$12.95. Each globe draws only 38rnA al 12 volls so abank
100 assorted LED's Inc. 3 & 5mm In yellow, orange, red &
CS JAYCAF
a
fuse
and
mains
lead/plug.
Two
pin
US
style
socket
of 20 globes draws only 760rnA, which enables you lo use
green. Rectangular, triangular and others. All for less lhan 9t
CS JAYCAF
mounted on case. Will deliver up lo 1.74 amps or 200
ea1
an Inexpensive 2155 transformer Cal. MM-2002 $10.95.
CS JAYCAF
95
walls.
'.; S JAYCAF
Use your own speaker llex type cable and save even more!
C~I. ZD-1696
Cat.
MF-1094
CS JAYCAF
All you require is Fig 8 speaker or mains cablelo use lhese
CS JAYCAF
bulbs.
CS JAYCAF
cable (speaker) to suit Cat. WB-1708 55t per rnelre
CS JAYCAF
Power supply 1 amp ·transformer - up lo 25 globes Cat.
CS JAYCAF
CS JAYCAF
MM-2002 $10.95
CS JAYCAF
2 amp transformer - up lo SO globes Cal. MM-2004 $16.95
CS JAYCAF
Cal. SL-2800
CS JAYCAF
CS JAYCAF
CS JAYCAF
CS JAYCAF
3.5 digit man'.Jai or auto range with logic probe and data hold. See catalogue for full details.
CS JAYCAF
Cat. OM-1420
;s JAYCAF
;s JAYCAF
;s JAYCAF
;s JAYCAF
;s JAYCAF
;s JAYCAF
;s JAYCAF
;s JAYCAR
;s J AYCAF
;s JAYCAR
;s JAYCAR
:s JAYCAR
:S JAYCAR
:s JAYCAR
:5 JAYCAR
:s JAYCAR
We have a lirnlled quanllly ol lhese quality chargers available. They are
Nol only is II a5 way power board, it tncorporales a voltage
:s J AYCAR
240Voperaled with an oulpul of 14.2V al 1.6A rnax. II ls an Intelligent
·s JAYCAR
surge and spike protector and noise rejection filler network.
charger, which means Iha! when !he ballery Is charged !he uni! will
.s JAYCAR
Supplied wilh lwo metre cord and mains plug, safely shuller
auiornali cally swilch itself lo trickle charge saving damage lo lhe ballery
,S JAYCAR
on each outiei, illurnlnaled rnasler on/oil and even a safely
and charger. Mos I Gel chargers don'! have ihis lealure.
:s JAYCAR
circuit breaker.
'', JAYCAR
II will charge our 6.SAh batleries In about 10 hours and our 15Ah cells In
95
~AR
Cal. MS-4030
about 20 hours. Oulpul lead lo ballery Is a3 pin Cannon type which In
S JAYCAR
mosl cases wi ll need lo be removed. Mains lead length 2 rnelrn~ . oulpul
30 PIECE ENGINEER'S
DRIVER SET
ECONOMY DESO'LDER PUMP
•s
NORMALLY
$9"SAVE $3 APRIL ONLY $6
SAVE $5 ONLY $14.95
0 .., , , . , . . . , . .~ - • • •
CALENDAR/CLOCK
INSIDE/OUTSIDE
DIGITAL
T HERMOMETER CLOCK
c::::::g
CD
i.~ ~ ~ ~
EB c:::::i:=; ~ ~ ~
~ ~ ~ ~
i . .~
$19
$ 2495
TECHLITE BULBS ·
LOW VOLTAG E
LIGHTING SYSTEM
240V-115V 200VA
Stepdown
Transformer
$8
$189 50
$1295
$ 5 995
&WAY POWER
OUTLET WITH MAINS
FILTER
$49
TELLIGENT GEL BATTERY CHARG
•t®f1J•I
- _v~AR
lead lenglh 1.8 rnelres. Size 175(L) x 1IS(W) x 60(H)rnrn.
Cal. MB-3507
SM APPROVED
AN ABSOLUTE BARGAIN
AT $69.95
JIGS
JIGS
JIGS
JIGS
JIGS
JIGS
JIGS
-
J AYCAR
JAYCAR
JAYCAR
JAYCAR
JAYCAR
JAYCAR
JAYCAR
ELECTRONICS
ELECTRONICS
ELECTRONICS
ELECTRONICS
ELECTRONICS
ELECTRONICS
ELECTRONICS
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JAYCAR
JAYCAR
JAYCAR
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JAYCAR
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ELEC TRONICS
ELECTRONICS
ELEC TR ONICS
ELECTRONICS
ELECTRONICS
ELECTRONICS
ELECTRONI CS
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JAYCAR
JAYCAR
JAYCAR
JAYCAR
JAYCAR
JAYC AR
ELECTRONICS JAY CAR
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\YCAR ELEC;
IYCAR ELECT
IYCAR ELECT
IYCAR ELECT
IYCAR ELECT
IYCAR ELECT
Anigh quality case and Included is hardware to mount 2 x 3.5
1YCAR ELECT
floppy drives and a hard disk. Rear panel is provided for typical
IYCAR ELECT
AT communicallons Including • modem • parallel port•
This keypad Is
1YCAR ELECT
designed lo be mounted near
printer • keyboard, etc. Front panel has flush mount 'turbo' and
1YCAR ELECT
your exlVenlry point allowing
reset switches along with 2 digit LED display to show CPU
1YCAR ELECT.
clock speed. Measures 41 O(WE) x 90(H) x 395(0). Power
your alarm panel lo be hidden.
1YCAR ELECT
supply provides +5V<at> 15A +12V<at> 5.6A, -5V<at> 0.5A, The keypad Is mounted on a
1YCAR ELECT
,YCAR ELECT
12V<at>0.5A
brushed stainless steel
,YCAR ELECT
mounllng plate. Ideal lo use
Cal.XC-5084
,YCAR ELECT
with all our alarms panels.
1YCAR ELECT
See catalogue
,YCAR ELECT
for full details and
,YCAR ELECT
50
specifications. Cal. LA-5160
NCAR ELECT
,YCAR ELECT
,YCAR ELECT
,YCAR ELECT
Two different modules are available. Both chime the hour
Our economy besl
,YCAR ELECT
after playing lhier
selling PIR lhal works
,YCAR ELECT
tune.
extremely well and Is
,YCAR ELECT
XC-0106 plays the
ultra reliable. It's so
,YCAR ELECT
Features:
Westminster Chimes
reliable that we have
,YCAR ELECT
• Erase up lo 9 chips at a lime
each hour then gongs
,YCAR ELECT
Increased the warranty
• Chip drawer has conducllve loam pad
the hour (I.e. 7pm - 7
.YCAR ELECT
pe~od lo one year. This
• Mains powered
gongs).
,YCAR ELECT
unit sold for $109 In
• High UV Intensity at chip surface ensures thorough erase
,YCAR ELECT
XC-0107 plays a
1988.
See
catalogue
for
.YCAR ELECT
• Engineered lo prevent UV exposure
different melody each
lull
details
,YCAR ELECT
• Long UV lube life
hour, then gongs the
Cal.
LA-5017
.YCAR ELECT
50
hour. Both units are
Cal. XE-4950
.YCAR ELECT
supplied with:
llleplac_,.nt tube Cat. XE-41151 $19.95
.YCAR ELECT
• Clock movement
.YCAR ELECT
.YCAR ELECT
• Speaker and battery
YCAR ELECT
holder (3 xAA balleries required)
YCAR ELECT
• 3 sets of hands
YCAR ELECT
Westminster Chimes Cal. XC-0106
YCAR ELECT
12 Melodies Cal. XC-0107
YCAR ELECT
115
YCAR ELECT
YCAR ELECT.
YCAR ELECT
Bands: FM-88/108MHz • AM-630/1600kHz • LWYCAR ELECT
150/280kHz • SW1 (49M) 5.85/6.20MHz • SW2 (41 M)
YCAR ELECT
7.10/7.50MHz • SW3 (31M) 9.45/9.90MHz • SW4 (25M)
YCAR ELECT
YCAR ELECT
11.50/11.95MHz • SWS (19M) 15.10/15.55MHz • SW6
YCAR ELECT
(15M) 17.45/18.00MHz.
YCAR ELECT
Listen to the world. II features 9 bands, LED tuning Indicator,
YCAR ELECT
3' speaker, fN DC external power Jack, earphone Jack, tone
YCAR ELECT
New range for 1991. Now made by the manufacturers of
switch. Requires 4 x AA cells. To operate on 240V mains use
YCAR ELECT
Re/Sponse drivers. See 1991 catalogue for lull details.
our Cat MP-3005 $15.95.
YCAR ELECT
50
YCAR ELECT
Cal. AR-2200
10" 65Wnns Cal. CG-2376
Ref: SIiicon Chip Sept 1990
YCAR ELECT
115
50
YCAR ELECT
Remote control your VCR from another room. Complete kll
12" 100Wrms cat CG-2380
YCAR ELECT
115
Cal. KC-5084
YCAR ELECT
12" 200Wnns Cal. CG-2381
YCAR ELECT
YCAR ELECT
15" 150Wrms Cal. CG-2382
YCAR ELECT
YCAR ELECT
YCAR ELECT
YCAR ELECl
YCAR ELECT
YCAR ELECT
YCAR ELECT
YCAR ELECT
YCAR ELECT
YCAR ELECT
YCAR ELECT
YCAR ELECT
YCAR ELECl
YCAR ELECT
YCAR ELECl
YCAR ELECT
YCAR ELECl
• Frequency
YCAR ELECT
• 4000counl
• Transistor lest
YCAR ELECT
• 39 range
YCAR ELECT
• Capacitance
• Inductance
YCAR ELECl '
• Data hold
• Capacitance
YCAR ELECl ,
• 20 amp current
• frequency
YCAR ELECl
Cal. OM-1560
• Temperature
YCAR ELECl
• Peak Hold
YCAR ELECl
• Logic
YCAR ELECl
YCAR ELECl
Cal. OM-1475
YCAR ELECl
YCAR ELECl
YCAR ELECT
YCAR ELECl
YCAR ELECl
YCAR ELFCl
YCAR [LECl
YCAR ELECT
YCAR ELECl
(CAn ELECTI
AC
Slide in style AT case including
150W power supply
Digital Access Keypad
Brand new
model
Don't pay $279 ONLY $169
MELODY CLOCK
MOVEMENTS
$69
Passive Infra Red
Detector
Ultraviolet EPROM
$1 09
$59"
9
MULTIBAND RADIO
• 9 BAND
ea
MUSICAL
INSTRUMENT
SPEAKERS
$49
$99
$1 59
$1 29
REMOTE CONTROL
EXTENDER KIT FOR
VCR'S
$59
$29
$189
-
$169
-
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NICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONIC(;JAYCAR ELI
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f: SIiicon Chip Nov 1989
JAYCAR ELI
you have an IBM or PC compatl bi
JAYCAR ELI
Ref: EA August 1986
YCAR ELI
wave radio you can plug Into the lnt
YCAR ELI
SCARE THE PANTS OF WOULD BE THIEVES! This car alarm
transmissions on the shortwave ban
Ref: SIiicon Chip Oct 1988
YCAR ELI
Is filled under the dash of the car. When athief breaks In (after
from the author (details supplied wit
INCREDIBLY POPULAR STEREO KIT!
YCAR ELI
entry delay) an unbelievably loud shrill sound goes off front panel, box a
You can connect your CD player (or record player) to the
JAYCAR ELI
INSIDE THE CAR making II too unbearable to proceed with
Cat. KC-5059
Mini-Mitter and then listen anywhere In the house, via your
JAYCAR ELI
stealing the car. The alarm has adash tamp flasher and entry
19
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Walkman personal portable. Also Ideal for playing CD's In
delays, a three second soft alarm to remind you to turn II off,
YCAR ELI
your car -via your portable CD player and your car
and automatic resetting. Two Inputs are provided. The Jaycar
JAYCAR
ELI
stereo/radio. The Mini-Mitter puts out 200 mlcrowatts. The
JAYCAR ELI
kit Includes the direct Import 116dB screecher, dash lamp,
Jaycar kit Includes PCB, case, front panel and all
JAYCAR ELI
PCB and all components.
components parts. Beware of Inferior kits.
JAYCAR ELI
Cat. KA-1675
Cat. KC-5041
JAYCAR ELI
50
115
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
JAYCAR E:LI
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
.JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
Ref: SIiicon Chip Jan 1991
.;;(YCAR ELI
Have fun al home with
1JAYCAR ELI
our new fruit poker
Ref: SIiicon Chip Aug 1990
JAYCAR ELI
machine kit. There are
.JAYCAR ELI
This new kit uses high speed CMOS
four symbols on the
.JAYCAR E:LI
ICs lo produce sine and square wave
.JAYCAR ELI
reels. Afor aces, 0 for
over the frequency range from 0.1 Hz
.JAYCAR ELI
oranges, Cfor cherries,
SOOkHz. II features excellent
JAYCAR ELI
and L for Lemons. The
specifications with a4 digl)
JAYCAR ELI
project Includes a
frequency read-out and an output
JAYCAR EU
speaker to give you
level control. This new kit Includes
JAYCAR EU
audible click-clicks like a
JAYCAR EL
PCB, box, punched and screened
real poker machine and
JAYCAR EL
front panel and all specified componen
JAYCAR EL
the reels even slop one
Cal. KC-5079
JAYCAR EL
after the over.
90
JAYCAR EL
The kit ls basically a
JAYCAR EL
short form one. It
JAYCAR EL
Includes PCB and all specified components. Wooden box
JAYCAR EL
and plugpack are not supplied. Plugpack use Cal. MP-3006
JAYCAR EL
JAYCAR EL
$15.95.
JAYCAR EL
Cal. KC-5039
JAYCAR [L
Ref: ETI Dec 1985
JAYCAREL
This unit ls a two transistor two stage transmitter that has the
JAYCAREL
benefits of being VERY COMPACT. The Jaycar kll contains all
Up to 30% cheaper than other suppliers. Grilles pressed out
JAYCAREL
specified parts and makes an Ideal, Inexpensive beginners kit.
of strong, perforated steel to protect HI FI or PA speakers In
JAYCAR EL
Cal. KE-4711
cabinets or cars, etc. Each grille has a rubber edge band and
JAYCAREL
black painted finish. Grille Is supplied with 4 mounting lugs,
JAYCAR EL
JAYCAREL
heavy duty screws and T-nuls (cabinet fixing spiked nuts.)
:JAYCAR EL
115
Cal. AX-3520 for 8' speakers
JAYCAR EL
Ref: SIiicon Chip May/June 1988
115
.JAYCAR EL
Cal. AX-3522 for 10' speakers
This Ignition gives extra high energy - essential for todays
.JAYCAR EL
95
high rewlng lean air/fuel ratio Ignitions.
.JAYCAR EL
Cal. AX-3524 for12' speakers
JAYCAR EL
• Slightly extra power
15
Cal.
AX-3526
for
15'
speakers
;JAYCAR l:L
• Slightly better fuel economy
.JAYCAR EL
• Much better weVdry starting
.JAYCAR EL
• Much greater time between tune-ups
;JAYCAR EL
The Jaycar kit Includes all o al specified co
;JAYCAR EL
Including die cast box, et
;JAYCAR EL
{:H'-t-f.;z-/,.::r:f,;l:;JAYCAR
EL
Cal. KC-5030
;JAYCAR El '
..JAYCAR ELI
:;JAYCAR EL
Protection for: microprocessors, terminals, micro computers,
;JAYCAR ELI
printers, disk drives and telemetry equipment. Used by
;JAYCAR ELI
government departments, schools, unlversllles, banks and TV
;JAYCAR ELI
stations.
.JAYCAR ELI
JAYCAR ELI
2 OUTLET Cal. MS-4025
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
JAYCAR ELI
Yes, that's correct. High quality Benelec brand 0.65mm
JAYCAR ELI
conductor, airspace PE dielectric, foll shield, 5mm OD
JAYCARELI
Jaycar
will
purchase
your
surplus
stocks
of
sheath, broon In colour air space, 750 coax. Save a
•JAYCARELI
components and equipment. We are
fortune over normal prices. 1oi metre for quantities less
JAYCAR ELI
continually on the lookout for sources of
than 100 metre roll.
JAYCAR ELI
prime quality merchandise.
Cal. WB-2002
JAYCAR ELI
CALL MARK HARRIS OR
JAYCAR ELI
JAYCAR ELI
BRUCE ROUTLEY NOW ON
JAYCAR ELI
(02) 747 2022
JAYCAR ELI
"SCREECHER" CAR
ALARM
MINI-MITTER · FM
STEREO
T ANSMITTER KIT
$44
$37
$34
149
MINIATURE FM
TRANSMITTER KIT
$26115
HIGH ENERGY
TRANSISTOR
ASSISTED IGNITION
KIT
METAL SPEAKER
CONE PROTECTOR
GRILLES
$9"
$1 0
$1 2
$14
$1 7
A~-..
SQU EEKY CLEAN
DOUBLE OUTLET
MAINS FILTE
$55
$1 09
750 COAX BARGAIN
AIR SPACED COAX AT
$35 100m ROLL
TURN YOUR SURPLUS
STOCK INTO CASH!!
$35 - 100 metre roll
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NICSJAYCAR ELECTRONICSJAYCAR
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Hung Chang 20MHz Dual Trace
Oscilloscone
UHF Wireless Burglar Alarm
• Wide bandwidth and' high se nsitivity • Intern al grati c ule rectangul ar
bright CRT • Built-in component tester • Front panel trace rotator
• TV video sync filter • Z ax is (intensity modulation) • Hi gh sensitivity X-Y
mode • Very low power consumption • Regulated power supply c ircui t
Cat. OC-1 900
Probes to sui t OC- 1902 $39 .50 ea
Was
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High quality Zeus brand direc t imported by Jaycar. Why wait until after you
have been robbed to in stall the alarm . See catalogue for complete details.
Comp lete system inc ludes
..... ----·- ----1 x Control Panel
1 x Pass ive Infra Red
Detec tor/TX
-.,..
:if,
$ . • ,,,..
1 x DoorM'i ndow Reed
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Detector/TX
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1 x Horn Speaker - 10
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1 x 240V AC adaptor
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1 x Set of batteri es for all TX
Cat. LA-5200
Spare PIR's, remotes available
''
ONLY $599
SAVE $50 over other suppliers
ACT DISKS AT EVEN
LOWER PRICES
CHEAPEST IN
AUSTRALIA?
onomy
Multimet
ew model for
s packed with lea
eeded by a disc j
1 mic input• 4 ste
ach input • VU me
40V mains operat
ee catalogue for f
17 range DMM at
a price that must
be the lowest in
Australia. Who
wou ld have
thought you could
buy a quali ty OM
for under $35 !
Compact size
which is ideal for
tool boxes , glove
compartm en ts,
etc. Uses a 9V
216 type battery
for long life (100
hours).
FEATURES
• 3.5 digit LCD d
• 3 range battery check
• Diode test
• Compact size 116(L) x
• Easy re-calibration inst
t.OM-1 430
at is
5.25" DSDD
5.25" DSHD
r
3.5"
DSDD
$28.95
Cat. XC-4721
3.5"
DSHD
$57.50
Cat. XC-4722
5.25" DSDD
$21.95
Cat. XC-4726
5.25" DSHD
$29.95
Cat. XC-4727
Prices for boxes of 1O disks
-
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ELECTRONICS
ELECTRONICS
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ELECTRONICS
ELECTRONICS
ELECTRONICS
J AYC AR
JAYC AR
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XC-4738
$3.95
Hiah Efficiency Electric Fence
This tfectric Fence has a high output and will energise up to 20km of live wire. It is a "short form"
uni t whic h consists of a fu lly assembled and tested PC board. No box or hardware is supplied.
SPECIFICATIONS
Input Voltage
9-15V DC
Input Current <at> 12V
140- 170mA
Output Energy<at> 12V 1.0 Joules
Pulse Rate<at> 12V
40-45 pul ses per minute
Output Voltage<at> 12V No load 6,500V
2,5000 6,200V
5000 5,000V
2000 3,200V
10002,ooov
.9 1
WAS
$46.95
$99 .00
$26.00
w
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N
Wire Length
Bat Life with 100Ah
Battery
Cat. ME-6010
R ELECTRONICS
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XC-4732
XC-4736
If you are new to
Electric Fences,
you will need this
manual. It has
12 pages full of very
helpful hints
and suggestio ns
relatin g to fence
des igns and sys tems,
types of
energise rs, fencing wire, gateway
and creeks , batteries , so lar panels,
cut out switches, insu lation,
horse paddocks and faul t fin din g.
Cat. BE-8300
NOW
Cat
XC-4730
ELECTRIC FENCE
MANUAL
$3
CHEAPEST IN
AUSTRALIA?
1990 Price
$9.50
$15.95
$15.95
$34.95
20km
26 days
fO
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$139.50
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ICS JAYCAR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JA YCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS
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. 3 JAYCAR
Ref: Silicon Chip Feb 1991
Ref: EA March 199 1
: 3 JAYCAR
Th is kit
Thi s simple
: 3 JAYCAR
enables
timer ki t may
3 JAYCAR
you to
be
used
as
a
: 3 JAYCAR
Ref: Silicon Chip Feb 1991
3 JAYCAR
bui ld a
parking
meter
Check audio gear etc with this low distortion
3 JAYCAR
hi gh
reminder, or
sine wave source. Low im pedance up to 8
3 JAYCAR
the basis•of a
3 JAYCAR
volts. Kit includes PCB , all specified
full
blown
3JAYCAR
components to build a 1kHz versi on. No
3 JAYCAR
plugpack su pplied.
: 3 JAYCAR
Cat. KC-5090
: 3 JAYCAR
3 JAYCAR
. l JAYCAR
: 3 JAYCAR
: l JAYCAR
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3 J AYCAR
3 JAYCAR
JAYCAR
Wash your windscreen with hot water and it uses no energy
JAYCAR
You can install it in minutes. The Hot Jet water reseNoir
JAYCAR
mounts on the radiator hose (between radiator and engine).
JAYCAR
Cut the thin tubing which carries water from the washer
JAYCAR
JAYCAR
reseNoir to washers and re-route through the Hot Jet
J
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reseNoir mounted on the radiator hose. Activate the
JAYCAR
washers to fill up the Hot Jet reseNoir, and in a short time
JAYCAR
the water will become hot for your windscreen. Everything
JAYCAR
su pplied. Made in the UK and imported by Jaycar.
JAYCAR
JAYCAR
Cat. XJ-2000
JAYCAR
JAYCAR I
'JAYCAR
'JAYCAR
JAYCAR
JAYCAR
JAYCAR
JAYCAR
Ideal for the hobbyist or handyman . Our lowest price 240V quality
Save mon ey by buyin g
JAYCAR
iron has a stainless steel, barrel. 25 watt.$
'AYCAR I
from Jaycar.
AYCAR '
Cat. TS-1450
•
Our SA 130 speaker kit is
AYCAR
$200
AYCAR I
less than other ki t
AYCAR
suppliers.
AYCAR ,
AYCAR
AYCAR I
3 way type fo r printers etc. See
AYCAR
AYCAR
Handl in g power
catalogue for full details.
AYCAR I
90Wrms.
AYC AR I
Complete with cabinets.
AYCAR I
Other
Vifa
kits
available
AYCAR I
All inputs/output D25 female with
JAYCAR I
see the Jaycar
JAYCAR I
gold contacts
· catalogue.
JAYCAR I
Cat. XC-5070
JAYCAR I
JAYCAR I
JAYCAR
JAYCAR I
Cat. XC-5072
JAYCAR I
JAYCAR I
JAYCAR I
Makes your vehicle appear to be alarmed for un der $8.
JAYCAR I
, JAYCAR I
The pack inc ludes a 120mCd 10mm diameter red LED, an d a b lack bezel. The
, JAYCAR I
120mCd
LED
is
a
s
bright
as
normal
red
beze
l.
Unit
requires
a
14mm
hole
See catalogue for full details
JAYCAR I
and simply snaps in. Add to this a cou ple of our burglar alarm stickers (Cat.
JAYCAR I
8"
80Wrms
LA-5100 - 95i ea) and your vehicle looks alarmed for under $~
JAYC AR 1
Cat. CW- 21 50
JA YC AR I
Cat. LA-5085
;i, •
JAYCAR I
10" 120Wrms
JAYCAR I
Cat. CW-2152
JAYCAR I
J AYCAR I
JAYCAR £
JAYCAR £
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The all new OK
JAYCAR I
Industries station
JAYCAR I
JAYCAR I
• Frequency counter
has set a new
JAYCAR I
• Ca pacitance meter
standard in cost
J AYCAR E
• Logic probe 20MHz
effec ti ve solderin g
JAYCAR E
stations for the
• Diode tester
JAYCAR E
• 10 amp
hobbyist
JAYCAR E
JAYCAR E
• 34 ranges
or manufacturer. It
JAYCAR E
• One hand operation
features a
JAYCAR E
Cat. QM-1 400
dial-up tem perature
JAYCAR E
be tween
JAYCAR E
3 15°C - 427°C
JAYCAR E
(600°F - 800° F).
JAYCAR E
. JAYCAR E
No more constant tip changing
JAYCAR
E
to select a different temperatu re.
JAYCAR E
For full specs see the b rand new
JAYCAR E
Jaycar catalogue. Cat. TS- 1600
JAYCAR E
JAYCAR E
JAYCAR E
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J AYCAR ELECTRONICS JAYCAR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR E
JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELECTRONICS J AYC AR ELECTRONICS JAYC AR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONICSJAYCAR E
JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTR ONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYC AR ELECTRONICSJAYCAR E
JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRO NICSJAYCAR E
JAYC AR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYC AR ELEC TRONICS JAY CAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR E
-
--
LOW COST SINE
WAVE OSCILLATOR
KIT
Fluoro Inverter Kit
$14.95
:VCAR F
PEAKER
JAYCAR SOLDERING IRON
&
1 95
SA130 3 WAY
KIT
D25 Type
$49.95
ONLY $999
Centronics Type
$49.95
a
5 95
$99.50
$129.50
THE OK SOLDERING
STATION
DIGITAL
MULTIMETER
WAS $99.95
NOW $79.95
SAVE $20
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100
Build this simple
12/24V light chaser
Looking for a simple circuit to sink
your teeth into? This 12V light chaser
has four separate channels, variable
chase rate, fuse protection and uses
just two ICs.
By DARREN YATES
Light chasers using light-emitting
diodes (LEDs) or low voltage light
bulbs have been around for ages. You
don't have to look far for examples. If
you go down to your local video store,
chances are you'll see a line of flashing lights in the window. Believe it or
not, our august publisher recently
travelled in a "stretch-limo" which
had little LED chasers running down
the interior of the car.
We wanted something a bit more
potent than a LED chaser, so we designed this circuit to drive 12V light
bulbs. There are four channels and
each channel can handle up to 36W
with only a modest amount of heatsinking. A single rotary control lets
you vary the chase rate from about
one flash every two seconds to four
flashes per second.
To make the circuit as versatile as
possible, we also designed it to run
from a 12V to 24V DC supply. This
means that you can power it from the
mains via a 12V DC plugpack supply,
or you can use a 12V or 24V battery if
no mains supply is available.
A small PC board holds all the parts except for the external pot. If you don't
need to vary the flash rate, the pot can be replaced by a fixed value resistor.
So, if you want to jazz up the interior of your purple Monaro or panel
van, this circuit is the one to go for.
For 12V supplies, we recommend that
you use the MES (miniature Edison
screw) lamps which are rated at 3W.
This means that you can use 12 lamps
per channel, or a total of 48 lamps for
the entire chaser.
How it works
If you look at the circuit diagram of
Fig.1, you'll see that there are only a
handful of components to the 12/24V
Light Chaser. In fact, the circuit is
based on two very common ICs - a
555 timer and a 4017 CMOS decade
counter. Let's see how it works.
ICl is the 555 timer and is connected as a simple variable frequency
oscillator. Its output frequency is determined by the l0kQ and 1.8kQ fixed
resistors, the lO0kQ potentiometer
(VRl) and the l0µF electrolytic capacitor. The lO0kQ pot varies the frequency from about 0.5Hz to 4Hz.
The output at pin 3 is a pulse waveform which is fed directly into the
clock input (pin 14) of IC2 , a 4017
CMOS decade counter.
On each rising edge of the incom ing clock pulses, one of 10 outputs of
IC2 goes high in turn, starting at pin
3. Since we only need the first four
outputs and not all 10, we connected
output 4 (which is actually the fifth
output since we count from zero) to
the reset input.
When this output goes high, it resets the chip and the first output at
pin 3 goes high again. There is a finite
delay as output 4 resets the IC but
because we are operating at such a
low frequency, it is almost instantaneous in effect.
So the sequence of events is this: at
switch on, the Q0 output (pin 3) is
high. When the next clock pulse from
ICl arrives, Q0 switches low and Ql
switches high. At the next clock pulse,
Ql switches low again and Q2
APRIL 1991
53
F1
5A
100U
10
+
16VWJ
16
IC1
555
14
i : : - - - - -""1 CLK
36W
MAX
IC2
4017
Fig.1: the circuit is
based on two low-cost
ICs. ICl is a 555 timer
wired as an astable
oscillator. This clocks
decade counter IC2
which switches its
outputs high in
succession. These
outputs then drive
transistors Q1-Q4 to
switch the lamps on
and off.
~
021"4_ _ _ _~2..,.2k~-------"if-1
15
RST
04
B0649
QJ;l'-7_ _ _ _ _ _..._2Y,.2k,.__ _ _ _ _---"t-t.
BCE
13
~
12V/24V LIGHT CHASER
switches high and so on until Q4
switches high and resets IC2. In other
words, the transistors act like switches
which are opened and closed one at a
time in sequence.
Each output ofIC2, at pins 3, 2, 4 &
7, is fed to the base of an NPN Darlington transistor (Ql-Q4) via a 2.2kQ
resistor which limits the base current
to about 3.5mA. Thus, as each output
of IC2 goes high in turn , the corresponding Darlington transistor turns
on and switches on the lamp(s) in its
collector circuit.
The Darlington transistors are
TO
TO
BD649s. These can dissipate up to
60W with suitable heatsinking and
also have a gain of at least 750 (but
typically above 1000). This means that
our 3.5mA of base current is turned
into about 3A of collector current
running through each transistor.
However, since only one transistor is
on at any one time, 3 amps is the
maximum current drain of the circuit, so the load on a car battery is
minimal.
To protect the ICs from the spikes
and surges that occur in most car electrical systems , we've included a 12V
LAMPS-Fi-.
q_
8
E C~~
100~1
N
~
ZD1
(t~
s1:c::;~SIS
TO
TO
E C~
~
N
'
k
IC2
Fig.2: follow this layout diagram
carefully when installing the parts on
the PC board. Fig.1 shows the pinouts
for the four power transistors (Q1-Q4).
The lOOQ resistor should be changed to
lkQ 0.5W if a 24V supply is used.
54
SILICON CHIP
zener diode across the supply line.
This also regulates the supply rail to
the ICs to +12V if a DC supply of
greater than 12V is used. Added protection is provided by the 5 amp fuse
which fits directly on the PC board.
The circuit also has protection
against reverse connection of the battery supply, although it may not be
apparent. Each of the Darlington transistors incorporates a reverse-connected diode from collector to emitter and these will conduct if the supply is reversed, turning on all the
lamps and (possibly) blowing the fuse.
The two ICs are also protected against
reversed supply by the 12V zener
diode which acts as a forward biased
diode if the supply polarity is wrong.
Construction
The 12V Light Chaser is built on a
small PC board coded SC08106911
and measuring 105 x 67mm. Whether
you buy or make the board, check
that there are no shorts or breaks in
the tracks. If you find any, use a small
knife to scrape away the excess copper or a dash of solder to bridge the
gap a~ required.
Fig.2 shows the parts layout on the
PC board. Begin by installing 12 PC
stakes at the external wiring points,
then solder in the wire links and the
two fuse clips. Make sure that the
fuse clips are M205 versions. These
are smaller than the standard 3AG
types.
Next, install the resistors. Table 1
shows the resistor colour codes or
better still, use your multimeter to
check the values. Note that the 100Q
resistor will have to be changed to
lkQ 0.5W for 24V operation. The three
capacitors can now be installed.
Check the polarity of the two electrolytics carefully (they both face in
the same direction).
Now for the semiconductors: install the two ICs and the zener diode
as shown in Fig.2, then mount the
four power transistors (Ql-Q4). Check
Fig.1 for the transistor pin connections. When they are installed on the
board, their metal tabs should face
the centre.
The 100kQ pot is connected externally as shown on the wiring diagram. It can be replaced by a fixed
value resistor if you don't need to
vary the flash rate. If you like, you
can mount the completed assembly
inside a folded aluminium case. Each
transistor should be fitted with a small
TO-220 clip-on heatsink for loads
greater than 12W. Make sure that the
heatsinks don't short together.
It's up to you how you wire up the
lamps. If you are using the MES
(miniature Edison screw) lamps, then
matching MES sockets are probably
the most convenient. However, these
sockets cost as much as the lamps
themselves and 48 at around 50 cents
each is getting a bit expensive.
As an alternative, you might also
consider using 12V mini lamps which
come with 10mm leads. These are
more expensive than the MES lamps
but may be more suitable for some
applications.
Make sure that the lamps are correctly rated for the voltage you are
using. If you are using a 12V supply,
then you can wire groups of 12V
lamps in parallel. If a 24 V supply is
to be used, you can still use 12V lamps
but these should be wired in series
pairs of two, with each pair then wired
in parallel.
PARTS LIST
1 PC board, code SC081 06911 ,
105 x 67mm
10 PC pins
2 M205 PCB fuse clips
4 TO-220 clip-on heatsinks
1 aluminium box to suit
1 100kQ potentiometer (VR1)
Semiconductors
1 NE555 timer (IC1)
1 4017 CMOS decade cou nter
(IC2)
4 B0649 NPN Darlington
transistors (01-04)
1 12V 1W zener diode (ZD1)
Capacitors
2 10µF 16VW electrolytics
1 0.1 µF metallised polyester or
ceramic (5mm lead pitch)
Resistors (0 .25W, 5%)
1 10kQ
4 2.2kQ
1 1.8kQ
1 100Q
Testing
Once you've finished the board, you
can install the fuse and power up the
circuit. To do an initial test , use a
LED and a lkQ resistor as the load for
each transistor. If it is working cor-
Miscellaneous
Heavy duty cable, hookup wire,
solder, etc
rectly, each LED should come on in
turn and the circuit should respond
by either increasing or decreasing the
chase rate as the 100kQ pot is rotated.
If it doesn't work, check the board
thoroughly for any solder splashes
which may be causing shorts between
the tracks. In particular, check between the IC pins. This done, check
that all components have been installed correctly and that the correct
value has been used at each location.
Once the circuit is working with
the initial LED load, you can then
replace it with any load you choose
up to 36W total for each transistor; ie,
you could use 12 3W bulbs or six 6W
bulbs, etc.
SC
Fig.3: here is the full size pattern for the PC board. Use it to check that your
board has been correctly etched before mounting any of the parts.
TABLE 1: RESISTOR COLOUR CODES
0
0
0
0
0
No.
Value
4-Band Code (5%)
5-Band Code (1%)
1
4
1
1
10kQ
2.2kQ
1.8kQ
100Q
brown black orange gold
red red red gold
brown grey red gold
brown black brown gold
brown black black red brown
red red black brown brown
brown grey black brown brown
brown black black black brown
APRIL 1991
55
A synthesised
stereo AM tuner, Pt.3
This month, we complete the construction
of the AM Stereo Tuner by giving stepby-step alignment details. This job is
simplified by taking advantage of the
microprocessor control.
By JOHN CLARKE
The AM Stereo Tuner can produce
very good sound quality but to achieve
this, the tuner must be aligned correctly. You do not need any special
instruments or tools apart from a plastic alignment tool and a multimeter.
Alignment involves measuring voltages and adjusting the various coils
and trimmers using off air stations as
the signal source.
The alignment tool can be purchased from your local electronics
supplier. Don't use a screwdriver to
adjust the coils. Its metal blade will
upset the adjustment and you run the
risk of cracking the ferrite slugs.
Powering up
Before switching on, make a final
56
SILICON CHIP
check on the wiring and check that
the fuse has been installed. This done,
set your multimeter to read voltages
up to 12VDC, connect its negative lead
to the ground pin next to TP2, and
switch on the power.
The display should light and show
522kHz. If not, switch off and correct
the problem before applying power
again. The problem could be lack of
power to IC1, so use your multimeter
to check for continuity between its
supply pins and its relevant voltage
regulators (ie, between pin 12 and the
output of REG2, and between pins 5
& 17 and the cathode of Dl 4).
Now re-apply power and measure
the voltages at the output of the regulators. Check that REG1 has an out-
put of 12V and that REG2 and REG4
are at 5V. REG3 should have about
5.6V at its output.
You should also check that the
supply rails to the ICs are correct. IC2
should have +5V at pins 6, 12 & 18;
IC3 should have +12V on pin 4; IC4,
+5V on pin 3; IC5, +5V on pin 14;
IC6, +12V on pin 4; IC7, +12V on pin
8; IC8 has no supply rail; IC9, +5V on
pin 1.
If all the supply voltages are correct, the tuner can be left powered up
unless a fault is detected during the
following tests or during alignment.
The next step is to check the operation of the front panel display and
switches. First, press the UP tuning
button and check that the frequency
readout increases from 522kHz to
1629kHz in 9kHz steps.
Each memory LED should light
when its respective switch is pressed.
Initially, all the memories will be set
at 522kHz. To program each memory,
select the required frequency using
the TUNING buttons, then press the
:ME switch and the required memory
switch.
The :ME LED should extinguish as
soon as a memory switch is pressed
PHONE LINE AND MAINS
FILTER/SURGE PROTECTOR
Protection for
nswering machines
ord/ess phones
acsimlles
or if the ME switch is pressed again. If
neither switch is pressed, the ME LED
should automatically extinguish after
five seconds.
The SEEK control should at this
stage send the tuner scanning up the
frequency band. However, because the
tuner is not yet aligned, do not expect
the tuner to lock onto a station. Press
any button to stop the tuner from seeking.
Check that the programmed memories remain intact when the tuner is
switched off at the power switch. If
not , check that REG3 is supplying a
5V standby voltage to pins 5 & 17 of
IC1 when the tuner is switched off at
the power switch but not at the mains
supply. (Note: the memories should
also remain intact for several hours if
the mains supply is interrupted, as
indicated in Pt.1).
Alignment
To align the tuner, we need to make
a series of adjustments. These are to
ensure that the local oscillator and
ferrite rod antenna tuned circuits track
each other, and that the range of the
varicap tuning voltage is within certain limits. The IF tuned circuits also
need to be peaked for best signal output and widest audio bandwidth.
Once this is done, the 3.6MHz oscillator is set for stereo reception and
the 9kHz twin-T filters adjusted.
Some of the alignment process involves switching from a low-frequency station to a high-frequency
station and then back again, with the
process repeated several times to ensure accurate tracking. This can be
done quickly, since the stations can
be programmed into memory for quick
access.
Local oscillator range
The first step is to adjust the local
oscillator so that it covers the range
from 972kHz to 2079kHz. The microprocessor (IC1) does all the frequency
measurements for us and controls the
local oscillator via a varicap tuning
diode. This ensures that the local
oscillator operates at 450kHz above
the frequency indicated by the display.
In practice, all we have to do is
ensure that IC1 remains in lock. This
lock requirement can be met by ensuring that the varicap tuning voltage
at test point TP2 operates between
defined limits. The procedure is as
follows:
• Connect your multimeter between
GND and TP2, select 522kHz on the
display and adjust 12 for a reading of
0.9V.
• Press the Down TUNING button once
so that the display jumps to 1629kHz.
Adjust trimmer capacitor Cl for a
voltage reading of 8V.
• Return to 522kHz (press the Up
button) and readjust 12 for 0.9V. This
done, select 1629kHz and readjust Cl
for 8V. Repeat this process until the
two voltages are within 0.1 V of the
required values.
The local oscillator range has now
been set. The next step is to adjust the
ferrite rod tuned circuit so that the RF
stage tracks with the local oscillator.
RF tracking
The RF section is aligned by measuring the AGC voltage at TP1. During
ensures that
lightning, power surges
and spikes do not
reach your ccstly
communication
equipment as it
ccnstantly monitors the
PHONE line and
the MAINS power line.
Simply ccnnect
to any existing power point,
plug in your fax, phone, video, Hi Fi or any other
240 VAC operated equipment and a series of
indicators shows the status of the mains
power point while several MOV's and gas
arrestors prevents access to damaging energy
sources. The CPE P- 1 is fully Telecom and Dept.
of Minerals and Energy tested and approved.
Imported and distributed by:
.ARISTI\
ELECTRONICS
Available through the following retailers:
Telegrafax PIL.
305-307 Sailors
Bay Road.
Northbridge. 2063.
NSW. (02) 9585137
Geoff Wood Elec.
229Burns
Bay Road.
Lane Cove. 2066.
NSW. (02) 427 1676.
ANTRIM
TOROIDAL TRANSFORMERS
* 15VA t.o 625VA from st.ock with
single 240V primary and dual
secondaries, 2 x 6V to 2 x 55V.
Standard models comply with
IEC65(BS415).
* 15VA to 2KVA to order with
dual 120V primaries and your
choice of secondaries. Compliance with AS3108(IEC742).
UL506 and other standards
available.
* High power audio toroids
available to order for 100V lines.
* Comprehensive data sheet
available.
* Competitive pricing available
for OEM and resellers.
HARBUCH ELECTRONICS P/L
90 GEORGE ST. HORNSBY, NSW
PHONE (02) 476-5854
FAX (02) 476-3231
APRIL 1991
57
The ferrite rod assembly is adjusted by sliding coil L1 along the rod, as
described in the RF tracking adjustment procedure. After the adjustments have
been made, the coil can be held in place by melting wax over both ends.
the ferrite rod slowly, noting the voltage reading for each movement. Take
your hand away before making each
reading and have the ferrite rod angled
away from the tuner case by at least
15°. Adjust the coil for a minimum
voltage reading.
• Select memory 2 and adjust trimmer Cl for a minimum reading on
your multimeter.
• Select memory 1 again and re-adjust Ll for a minimum voltage reading.
• Repeat the procedure for the memory 2 station, then check the memory
1 adjustment again. The two settings
should now be correct.
• Connect your multimeter between
TP2 and GND and select the 20V range.
Check that the varicap tuning voltage
is at least 0.9V when the display is set
to read 522kHz. If the voltage is below this, readjust the LZ slug for a
reading of 0.9V.
• Set the display to 1629kHz and
check the voltage reading. If the voltage reading is above 8.5V, the local
oscillator range will need to be reset
as described previously. This also
means that the RF tracking will have
to be readjusted as described above.
Fortunately, all these adjustments can
be done quite quickly.
IF alignment
Heatshrink tubing should be shrunk over the ferrite rod assembly at the
conclusion of the alignment procedure. This will provide a degree of protection
against bumps & knocks & will further ensure that coil L1 is locked firmly in
position.
this process, you need to slide Ll
along the ferrite rod to find the point
of maximum signal pickup when
tuned to a low-frequency off-air station. Cl is then adjusted for maximum signal pickup when tuned to a
high-frequency off-air station.
Using Cl to peak Ll means that the
local oscillator varicap voltage range
is altered again, and so this will require further readjustment. But that's
58
SILICON CHIP
life. Here's the step-by-step procedure:
• Select a local radio station which
is near 603kHz and tune to this station. Now program it into memory 1.
Select another local radio station
around 1305kHz and program this
into memory 2.
• Connect your multimeter between
TPl and GND and set it to the 2V
range.
• Select memory 1 and slide Ll along
The mixer coil (L3) and the IF coil
(L4) must now be adjusted so that the
tuned circuits peak at 450kHz. When
peaked, they will provide the best
audio bandwidth for the tuner.
• To align the IF stages, connect the
multimeter between TPZ and GND and
select the ZV range. Now select a radio station (memory 1 will do) and
adjust the slugs in L3 and L4 for a
minimum voltage reading.
• Now go back and realign the RF
section (ie, repeat the procedure set
out under "RF tracking"). This is done
because with the IF coils peaked, you
will be able to more accurately peak
the RF coil (Ll). After the RF stage
has been realigned, the 450kHz IF
coils (L3 & L4) should be readjusted.
• When these adjustments have been
completed, secure the antenna coil
(Ll) by melting wax over both ends.
This done, fit heatshrink tubing over
the entire assembly (including the PC
board), as shown in the photograph.
Signal level display
At this stage, you will be able to
Be sure to use a plastic alignment tool when adjusting the various coils on the
PC board, otherwise you could damage the ferrite slugs. Note that all the
adjustments are repeated several times, as detailed in the text, to obtain the
optimum result.
check the signal level display for correct operation. Tune to various stations using the Up and Down TUNING
switches and check that the signal
level display operates correctly. On
strong stations, all five LEDs should
be lit. You can adjust the angle of the
ferrite rod for best signal pickup.
3.6MHz oscillator
The 3.6MHz oscillator coil (L5)
must be adjusted so that this oscillator locks onto the 450kHz IF. Thi'.s
will enable the tuner to provide a
stereo signal. The procedure is as follows:
• Connect your multimeter across the
2.2kQ resistor on pin 3 of IC2 and
select the 5V range. Tune to a local
station and adjust L5 until the voltage increases to about 2.5V. If the station is transmitting in stereo, the voltage should then suddenly increase to
4.5V and the stereo LED should light.
• Rotate L5's slug slowly clockwise
and note the position where the voltage drops to 0V from the locked 2.5V
setting. This done, rotate the slug
anticlockwise and again note the position where the voltage drops to 0V.
Set the slug midway between these
two positions.
Seek control
The seek control adjustment is
made with trimmer capacitor C2. This
sets the seek sensitivity so that it only
locks onto stations with good signal
strength.
• Press the SEEK button and check
whether the tuner stops at a station. If
it doesn't, adjust C2 for greater capacitance (ie, plates further in mesh)
and try again. Conversely, if the tuner
stops at every 9kHz step, adjust C2
for lower capacitance.
C2 is correctly set when the tuner
only stops at stations with at least
one LED lit on the signal strength
meter.
9kHz filters
The twin-T filters are designed to
provide a notch at 9kHz in the audio
path, to filter out adjacent channel
interference. There are two adjustments to be made for both the left and
right hand channels. This can be done
using off-air stations at night when
9kHz whistles are prevalent.
• Switch the power off and set your
multimeter to the kilohm range. Connect the meter probes to the top of the
18kQ resistor (ie, the junction of the
two 270pF capacitors) in the left channel and to pin 8 of IC3. Adjust VR3
for a reading of 32. 76kQ.
• Similarly connect the meter probes
to the top of the right channel 18kQ
resistor and pin 14 of IC3 and adjust
VRl for a reading of 32. 76kQ.
• Rotate VR2 and VR4 fully cl ockwise. This should give a notch which
is close to 9kHz. Note: if these trimpots are rotated fully anticlockwise,
the twin-T filter will be disabled.
• Connect the tuner to an amplifier
and tune to a station at night which
has a substantial whistle. Use the
balance control of your amplifier to
select the left channel only and adjust VR4 until the whistle is eliminated. Similarly, select the right channel only and adjust VR2 so that the
whistle is minimised.
Your new tuner is now ready for
stereo hifi listening. In some cases,
the ferrite rod may have to be adjusted to give the best reception although this will not be necessary on
strong local stations. This simply
involves angling the rod away from
the rear of the case to increase signal
pickup.
SC
APRIL 1991
59
HUGE STOCK CLEARANCE
PRICES DRASTICALLY
REDUCED ON MOST ITEMS
See Altronlc's new 1991 catalogue for our full range. If you haven't received your
copy yet, send $1 to cover postage and packing to:
AL TRON ICS MAIL ORDER, PO BOX 8350 PERTH STIRLING ST, W.A. 6849.
roduclng Altronic's New Sensational Labtech 20 MHz CRO
Australla's Best Value In High Rellablllty, Top Performance
Cathode Ray Oscllloscope.
This model is a dual trac.e 20MHz Oscilloscope using a hi~h
brightness CRT. The vertical amplifiers have high sensitivity of
5mV div and a frequency characteristic response with smooth roll
off exceeding 20MHz.
The TV sync. si~nal separator circuit is provided to ensure stable
observation of video signals. Triggering is obtained by sampling
. the AC power waveform, external waveform or internally
generated trigger. Power consumption is only 19 watts and
weig ht is only 7kgs.
$
Full 12 Month• Warranty
•
Q 0156 FANTASTIC VALUE AT ONLY
Probe Sets
Q 0175 $49.95 each
699
Speclllc ■ Uon1 Position x 10 Bandwidth: DC to SOMHz
Max Input Voltage: 600 Vo lts DC Position x 1 Bandwith:
DC to 3MHz Max Input Voltage: 600 Vo lts DC Probe
Length: Approximately 1.5 meters
End Poly Emulsion Coated Cone Woofers at Direct
Altronic Distributors announces the release of a new generation of high end woofers. The development of high grade driver
components in Japan, such as Barium ferrite magnets and specially formulated paper cones impregnated with po ly
emu lsion, have enabled us to offer our customers drivers of quite remarkable power handl ing, performance and extremely
low distorition.
We bel ieve the performance exceeds that obtainable from many European ··name" brands; and the direct import prices Cone
Materials. This series of loudspeaker features a specially selected fibre impregnated paper cone which is coated with a layer
of polypropy lene to c:dd the desired rigidity. An added benefit .of this coating is its resistance to water and moisture ingress.
Voice Coil Construct1on. All voice coils are wound on aluminium. the magnet pole pieces are vented for heat dIssIpat1on.
Bump back plates are employed to allow extra voice call excursion .
·
Rated Power .40W
Max. Power ... 60W
Impedance .... Sohm
Freq. Rasp . ... F0-5kHz
Res. Freq .... ... 70Hz (+/ -14Hz)
Sensitivity ..... 96dB/ W(0.5m)
Magnet .......... 567 gm/20oz
C 3022
$49.95
':CC' Woofer
W
MS 100W
C 3024
$69 .00
21st Century entertainment fascinate your friends!
Amazing! Pulsating high voltage
plasma discharge continually
changes shape and direction. Mode
selectable to either fingertip control
or sound activated . For example,
from voice or sound system.
Provides endless fascination as it
sizzles and arcs.
Supplied complete with AC mains
adaptor.
A 0120 Normally $199.oo
SAVE $50.00
M ■x .
Rated Power .60W
Max. Power. .. 100W
lmpedance .... Bohm
Freq. Resp .... F0-4kHz
Res. Freq ....... 60Hz (+/-12Hz)
Sens itiv ity ..... 9BdB/W (0.5m)
Magnet .......... B48gm/ 30oz
10" PECC Woofer
80 Walto RMS 130W Max .
Rated Power .SOW
Max. Power ... 130W
Impedance .... Bohm
Freq. Resp .. .. F0-4kHz
Res. Freq ...... .2BHz (+/-SHz)
Sensitivity ... .. 97dB/W(0.5m)
Magnet .......... 1170gm/41oz
12" PECC Wooter
15" PECC Woofer
80 Walla RMS 160W Max .
100 Walla RMS 200W Max .
Rated Power .BOW
Max. Power ... 160W
Impedance .... Bohm
Freq. Resp .... F0-3kHz
Res. Freq ....... 25Hz (+/ -SHz)
Sensitivity ..... 98dB/W( 0.5m)
Magnet .......... 1408gm/50oz
Rated Power. 100W
Max. Power ... 200W
Impedance ....BOhm
Freq. Resp .... F0-3kHz
Res. Freq .... .. 25Hz (+/ -SHz)
Sensitivity ..... 98dB/W(0.5m)
Magnet ...... ....1835gm/65oz
c 3026 $99.95 c 3030 $125.oo c 3032 $198.oo
MICRON SOLDERING STATION
Electronic Temperature Controlled-Temperature Selectable, Soldering
Station . Now th is is really quality and versatility! Now supplied with long
life ceramic cartridge heater.
The MICRON T2440
T 2440
soldering station offers the
◄ CK.
ultimate in controlled
~;,.95
temperature, hand
soldering. Simply rotate
detained rotary switch
·
freely to selectable fixed
temperatures of: 320° C
(608°F), 350°C (662°F),
380°C (716°F) 410°C
(770° F), 440° C (824 ° F)
without changing heater or
tip.
Packed with features:
Temperature readout &
control; Zero voltage
switching; Grounded tip;
Low voltage element;
Chrome plated, iron clad
tip.
$
$139
BAG YOURSELF A KIT BARGAIN!
FM Stereo Transmitter (See sc Oct
e
__,
<at>
K 1120
$~o $39.50
'88)
Simply connect your CD player to
the mini mitter which converts the
CD signal to an FM signal. This FM
signal then can be tuned In via your
FM walkman or your shed radio.
Great for listening to your favourite
CD while washing the ca r, mowing
the lawn or doing the vacuuming etc,
without blasting the neighbours.
AC/DC Millivolt
Meter
(See Ea Dec '87)
Precision measure critical circuits.
• AC/ DC range
• 7M Ohm input impedance
• 10mV to 30V ranges in 8 steps
• Zero position
• Battery Test position
K
FEATURES:
·-
K 3210 $~00 $99 .oo
2670 $~0 $45 .00
Door Minder
(See SC Feb '88)
.
This project will sense a door opening in a
large or small room and will sound a two-ton e
chime. It does not have to be anywhere near
the doorway as it uses an ingenious sensor to
detect the pressure change caused when the
door opens.
K 191 5 $Ji':f)o $34 .50
The Electronic Canary
Get th at atmosphere of
tra nqui lity that o nly birds can
gi ve . The rea lism of t his
proj ect is remarka bl e.
Sou nds for all the world like
two tr illi ng canaries.
• Saves t he mess of birds
• Battery powered
• Easy to bui ld
K 1130 ~ 5 $19.95
Automatic Charger
for NiCads·csee EA July '89)
24V to 12V DC
Converter
(See SC Dec '87)
This supply was designed
to enable 12V appliances ~
like stereso , 2 Way Radios,
.·
CB 's etc. to ope rate from a (I,
24V battery supply as used
in trucks , 4WD's and boats ,
·
w ithout causing expensive
damage to the vehicle
.
battery system .
K 3255 $~
• Output variable between 3
and 30V • Short circuit
protection • Full 1 amp output
over entire voltage range •
Load switching • Current
limiting fully variabletwin
selectable ranges-dual scale
' meter • Separate earth
terminal provided • Housed in
our Deluxe "ABS" in-,trument
case.
• · .·
· •
_......,_,..~..:..JU
0 $49.00
50MHz Digital
Frequency Meter
(See EA May '88)
Easy to build & construct t his
fantastic meter measures to well over
50MHz in 5 ranges. Features high
input impedance, overflow LED
indicator, KHz & MHz LED
indicators. All componenets mount
onto single PCB , even the selector
switch.
K 251 0 ~ o $89.oo
K 1650
~ o $29.95
Get 100's more recharge cycles from
your nicads.
Its now well kno wn that correctly
charging nlcad cells greatly extends
their service life.
Here is a fully automatic NiCad
battery ch arger that enables differing
charge rates as appropriate for AAA ,
AA, C, D cells or cells in series up to
9V. On ce the battery is charged , the
unit automatically switches to trickle
charge until you switch it off. It is
fully featured, yet surprisingly
simple.
····
Telephone Off
Hook Indicator
Use where 2 or 3 phon es are connected
on one line . If one extension is in use a
LED wil l f lash in each of the other
extensions . Req ui res no _external supply.
K 1400 $9 .95
Speech Synthesizer
Here is a self contained Speech Synthesizer that
does not require a computer to control it.
(ETI March '88)
Low Cost Temperature Probe
Here's an easy to build
probe which adapts a .
multimeter or electronic ·
voltmeter into a general
purpose thermometer. Ifs
Just the shot for measuring
heatsink temperatures, how
hot it gets inside your car,
or where little Johnny has a
fever!
Measurer& accurately from 20 deg.C to =120 deg.C.
K 2570 $21 .95
K 9500 $J).i':1)0
$ 89.oo
K 9502 Pre-Programmed
E rom for K 9500 $20.00
This small, simple circuit contains
all th e necessary components to
make your favourite possessions
speak . It can be connected to
almost any appliance, vehicle or
home ~emote control system to let
you know when the kettle has
switched off , the doors are locked
or the water in the radiator is
boiling . The inputs are coded and
priori ty message reading means
warnings are heard instead of
greetings etc if two messages are
sent at the same time. Blank
Eprom included to allow you to
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....
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A practical approach
to amplifier output
stage design - Pt.2
Last month we introduced the topic of
amplifier output stage design and looked
closely at the selection of output
transistors. In this article, we look at
driver transistor selection and then
calculate the heatsink requirements.
By DAVID EATHER
Last month, we concluded with
Tables 3 and 4 which were the load
line calculations for the driver transistors in the circuit of Fig.1, a straightforward 25 watt amplifier.
The next step is to go to your data
book and draw the SOAR curves for
the BD139/140 transistors. Having
done that, plot the load lines from
Tables 3 and 4 on to the same graphs.
When you have finished, you should
find that the curved load lines are
fully enclosed by the straight line SOAR
graphs. The complete plot was shown
in Fig.3 and shows that BD139/140
driver transistors are indeed quite suitable for this application. For convenience, we reproduce Fig.3 in this article.
With this done, you have finished
selecting the output and driver transistors. Now we will move onto calculating the heatsink requirements of the
amplifier. This is where, if you made
64
SILICON CHIP
the right choices for transistors, it all
comes together.
Selecting the heatsink
The object of selecting a heatsink is
to keep the transistor junction temperature below the maximum permissible while still allowing it to dissipate the required power. If the junction temperature rises above the specified maximum, the transistor will
probably fail. In any case, it makes
good sense to keep the transistor junction as cool as possible. Every 10°C
lower approximately doubles the transistor's life.
When considering how a transistor
dissipates heat, it is useful to think of
Ohm's Law. The heat produced by the
transistor chip is analogous ,to current. The actual temperature at any
point is similar to voltage and thermal
resistance is like electrical resistance.
Fig.4 is a simplified thermal model
of a single transistor mounted on a
heatsink. Notice that there is a resistance between the transistor junction
and the transistor case (Rth j-c). This
is one resistance you can do nothing
about. The method of manufacture and
the type of transistor case determine
Rth j-c. The other thermal resistances
you do have some control over. These
include the case to heatsink (Rth c-h)
and heatsink to ambient (Rth h -a) resistances.
All the components also possess
some thermal capacitance. When heat
is produced at the transistor junction,
the temperature does not rise immediately but climbs more slowly to the
peak value. The values of thermal
capacitance for the transistor chip,
case and washers are small when
compared to even a modest heatsink.
So for this reason, it is possible to
ignore them without significantly affecting the results, in most cases.
There is another thermal path that
you should be aware of, even though I
won't use it here. It is the heat flow
from the case to the surrounding air.
The specification is given as either
case to ambient (Rth c-a) or junction
to ambient (Rth j-a). Either way, it acts
as a parallel resistance from the specified point (junction or case).
The net effect is to lower the total
thermal resistance to ambient. Sometimes there is no value specified or
the value is so large that it makes little
diffe~ence to the final r~sults.
Calculating how to keep the transistor junction at a safe temperature is
easiest by using the SOAR curves/load
lines you have already plotted. You
also need to use the temperature derating curves on the data sheets or the
formula given later.
At this point, there is no longer any
advantage in considering the output
10
....
"\
\
\
__ill
,__Jill
0.1
I\
I\ I'\
I\
I
I
I
\
.01
\\
1
10
100
Vee (V)
Fig.3: repeated from last month, these
curves show the load lines for the
driver transistors (plotted using the
data shown in Tables 3 & 4). As with
the output devices, the load lines must
be fully enclosed by the DC SOAR
curve of the transistor.
at the same voltage while the current
changes.
Make sure that part of the SOAR
curve just touches the outside of the
transistor load lines. Check that the
load lines are still fully enclosed by
the new SOAR curves.
My new graphs are Fig.5 and Fig.6.
Power dissipation is the limiting factor for Fig.5 because the curved load
line touches the upper set of sloped
lines (which represent the power dissipation limit). In Fig.6, secondary
breakdown is the limit because the
curved load line touches the lower set
of sloped straight lines (which represent the SOAR-limited power dissipation).
Look at the power limited section
of the new SOAR curves. At a convenient point on the curves, calculate the
maximum derated power dissipation.
Do this calculation even if secondary
breakdown was the limiting factor
with your transistor. Note the figures
down. Mine are 84 watts for the output transistors (Fig.5) and 5.5 watts
for the drivers (Fig.6).
0
I'\
10
)\~
I'\
I'-
....
....
I,
1'.
' ' 1'.
....
- --~1'
....
I°'
I'-...
\
[/
I
-....."-
\
\
""
l\
\
\
'I
'l
0.5
I
I
\ \
0.3
\
\
'
20
10
30
60
Vee(V)
Fig.5: graph showing the derated
SOAR curve for the output
transistors. This curve is derived by
constructing new power limited &
secondary breakdown lines parallel
to the original lines, so that they just
touch the transistor load line.
Maximum case temperature
....., ,-JUNCTION TEMPERATURE
RTH(j·e)
, CASETEMPEAATUAE
RTH(e-h)
• HEATSINK TEMPERATURE
RTH(h•a)
•-:-• AMBIENT TEMPERATURE
Fig.4: simplified thermal
model for a single transistor
mounted on a heatsink.
If available, use the temperature
derating curve on the data sheet to
find the maximum permissible case.•
temperature. Some data sheets have
the graph scaled directly in watts
while others may use a percentage of
the maximum power.
The data sheet for the.BD139 comes
with a temperature derating graph.
This graph gives a maximum case
temperature of95°C.
Those data sheets without temperature derating curves can use the following formula to calculate the maximum case temperature:
10
....
"\
,_
Derated SOAR curves
On the load line graphs you have to
find how far the transistor SOAR curves
can be derated while fully enclosing
the load line.
Draw derated SOAR curves by constructing new power limited and secondary breakdown limited lines parallel to the original lines. The point
where the "power limited" line becomes secondary breakdown remains
Tj max is the maximum temperature of the transistor junction. At Tj
max, the transistor's power handling
drops to zero. 200°C is the most common value for hermetically sealed
transistors (metal case) and 150°C for
most non-hermetic (plastic) types.
P is the derated power of the transistor from above. Pmax is the maximum power the transistor can dissipate.
Tj min is the highest junction temperature at which the transistor can
dissipate Pmax. It is usually, but not
always, 25°C and is next to Pmax on
\\
'\l\
0.1
'
I
Tease max =
Tj max - P/Pmax x (Tj max -Tj min)
stage and driver stage separately.
Apply the following steps to both
stages.
'
""\
I
I'
I
~
.01
1
'\
\\
10
100
Vee (V)
Fig.6: graph showing the derated
SOAR curve for the driver transistors.
Note that· secondary breakdown is the
limiting factor here, while power
dissipation is the limiting factor for
Fig.5.
the data sheet. For example, Tj min
for the 2N3055 is 25°C and for the
BD139, 70°C.
For the example of the output stage
APRIL
1991
65
Amplifier output stage design ...
in my design, the following values are
derived from the data sheet: Pmax
equals 115 watts; Tj maxis 200°C; and
Tj minis 25°C.
p· comes from the derated SOAR
curve above and in this example is 84
watts.
Poking all the numbers into the formula gives:
Tease max = 200 - 84/115 x (200 - 25)
= 200 - 0.73 X 175 = 72°C.
Now is as good a time as any to
decide what heatsinking configuration
to use.
Mathematically, the simplest approach is to mount each transistor on
its own heatsink. This has some practical advantages too. With the heatsinks electrically isolated, the insulating washers are superfluous. The
lower thermal resistance (Rth c-h) can
result in smaller heatsinks or greater
reliability. One problem (beside cost)
is the greater difficulty in providing
the bias current with thermal stabilisation.
A common heatsink
The most common approach is to
mount all the transistors with insulating washers on a common heatsink.
Check carefully to see if there are
any other possibilities that could result in significant benefits. One example would be if you designed an
amplifier with only the output transistors connected in common collector mode. Mounting these transistors
without insulating washers is possible
with an electrically isolated heatsink.
This could lead to some savings with
either the type of transistor used or
size of heats ink.
Fig. 7 is a simplified diagram of the
thermal paths for my amplifier. I've
used the commonest approach and
mounted everything on the one
heatsink and used insulating washers
on all the transistors. The values used
for Rth c-h are from Table 5 which is
collated from a variety of sources.
If you are using a transistor package
66
SILICON CHIP
not listed in Table 5, make an ap proximation based on the mounting
area of one of the listed packages.
Heatsink compound
Notice that the use of heatsink
compound reduces the thermal resistance to one fifth, making it well worth
using.
There is one last formula to use
before the completing the amplifier
design. Truthfully, there is a little more
than one but the rest are trivial.
You have to calculate the average
power dissipated in the transistors
while driving the load. The formula
is:
Pave diss = [(Vee - Vripple/2) x
Imax]ht - [Vmax load x Imax load x
cos0]/4
Subtracting half the ripple voltage
from Vee gives a simple approximation for the average voltage supplied
to the transistors.
Use the values associated with the
nominal load impedance for your
amplifier. The calculations for my
output stage are:
Pave diss = [(27 - 3/2) x 2.5]ht - (20 x
2.5 x cos45°]/4 = 11.41 watts.
And for the driver transistors:
Pave diss = ((27 - 3/2) x 0.125]/n - [20
x 0.125 x cos45°]/4 = 0.573 watts.
Thif' is the average power dissipated
Ti,01
Tj, 02
Tj, 03
2oo·c MAX
01 RTH(j-c)
01 RTH(c-h)
Ti, 04
15o•c MAX
04 RTH(j-c)
02 RTH(c-h)
o.JJ·ctw
03 RTH(c-h)
04 RTH(c-h)
3•ctw
HEATSINK TEMPERATURE
(MAX 68.23°C)
RTH(h-a)?
AMBIENT 4o•c .,.
Fig. 7: simplified diagram showing all
the thermal paths for the amplifier
(note: driver & output transistors all
mounted on the same heatsink).
by the transistor when producing a
continuous full power sinewave into
the nominal load. As you would expect, these values are quite a bit lower
than the peak values calculated earlier.
This is not the worst case figure
which is obtained when the output is
shorted. Driving the amplifier into
clipping also produces higher power
dissipation. Both of these conditions
are abnormal and can be protected
against by the careful selection of fuses
or electronic limiting.
Now comes the part that is a little
hit and miss, like fitting in the last
parts of a puzzle. Exactly how you
proceed depends on what you have to
fit into place. The object is to find the
heatsink size that allows the transistor cases to stay below the maximum
temperatures calculated before. For
my example, I have all the transistors
on one heatsink and I'll proceed as
follows.
Heatsink size
First, find the maximum permissible heatsink temperature for both
transistor stages. This is simply the
maximum transistor case temperature
minus the thermal resistance to the
heatsink times average power dissipation of the transistor.
Tmax heatsink = Tease max - Rth c-h
x Pave diss
Remember that Pave diss is like
current in Ohm's Law. The heat dissipated flows through a thermal resistance and produces a temperature
gradient across it. Rth c-h comes from
Table 5.
For the output stage of my amplifier, the formula becomes:
Tmax heatsink = Tease max - Rth c-h
x Pave diss = 72 - 0.33 x 11.41 =
68.23°C.
Similarly, for the driver stage,
the maximum heatsink temperature
would be 93.28°C. Because in this case
all the transistors are mounted on the
one heatsink, 68.23°C has to be the
maximum allowable temperature.
The next step is to find the total
heat flow into the heatsink. This is a
simple addition of the power dissipation of all the transistors. For my example, there is the power dissipated
by the two driver transistors plus the
power dissipation of the two output
transistors.
Table 5: Thermal Resistance (c-h) For Common Packages
T0-3
T0-66/SOT-93
T0-220
T0-126
Insulating washer
No heatsink compound
1.50
4.55
5.68
13.64
Insulating washer
Heatsink compound
0.33
1.00
1.25
3.00
No insulating washer
No heatsink compound
0.50
1.20
1.50
3.60
No insulating washer
Heatsink compound
0.10
0.24
0.30
0.72
gives a compact design that will fit
inside a "one unit high" rack mounting box. The larger heatsink also
means that the amplifier will safely
handle quite a bit of sustained thrashing. You beauty!
Fuse selection
This gives a total of 23.97 watts
dissipation. Now make an approximation of the maximum ambient temperature inside the amplifier enclosure. 40°C is a commonly used figure.
Another item to consider is the use
of a mounting bracket for the transistors. The mounting bracket adds further thermal resistance between the
transistor and the ambient temperature. In many cases, simply adding 5100C to the ambient temperature deals
with the problem. But it is better to
use the thermal resistance, if you know
it.
The final value ofheatsink thermal
resistance is another simple application of Ohm's Law. You know the heat
flowing in, the temperature gradient
(maximum heatsink temperature ambient) and you need to find the
thermal resistance.
Rth h-a = (Tmax heatsink T ambient)/Ptotal dissipation=
(68.23 - 40)/23.97 = 1.18°C per watt
That's equivalent to just over
150mm of common fan type heatsink.
Unless you need a very sturdy amplifier, such a large heatsink will almost
certainly make this design uneconomical.
Smaller heatsinks
Fortunately, the situation of an
amplifier delivering its full power on
sinewaves for more than a minute is
not common. Even the most determined organist is unable to remove
every rest from a tune. Music and PA
amplifiers produce peak power for
only a small percentage of the time.
This means you can use a smaller
heatsink than shown above because
the average power dissipation of the
amplifier is much less. The large thermal capacitance of the heatsink will
smooth out any high peaks in temperature.
How much smaller can you make
the heatsinks? There a two widely
used rules of thumb that can help to
guide you.
The first rule of thumb says that
with the worst case signal (rock music
from an FM station), the average power
dissipation equals 15% of the peak
output.
For my amplifier above , this would
mean the heatsink needs to cope with
an average dissipation of 3.6 watts.
That works out to a thermal resistance
of 7.8°C per watt: A piece of aluminium a bit bigger than normally used as
a heatsink mounting bracket will suffice . The amplifier case would also be
suitable. This size of heatsink makes
the amplifier suitable for home use or
anywhere it will be treated with some
respect.
The other rule of thumb is the peak
music power figure which says the
average power equals the peak power
divided by 2¼. This usage has nothing
to do with the shameless way some
manufacturers use peak music power
figures to boost sales.
This calculates to an average dissipation of 10.6 watts, requiring a
heatsink with a thermal resistance of
2.7°C per watt. Any of the multipurpose 75mm-long heatsinks will work.
This amount of heatsinking gives an
amplifier suitable for most professional and semi-professional applications.
The choice of a 75mm-long fan type
heatsink provides an interesting design. Mounting the transistors through
the heatsink directly onto the PC board
One furth er step is the selection of
fuse protection. Fuses are not optional.
It is true that the output transistors
often blow before the fuse. Don't make
the mistake of saying "the transistors
often protect the fuse by blowing first".
Fuses go open circuit, transistors
normally go short circuit. If an output
transistor goes short, the speakers are
connected directly to your power
supply. Without a 50-cent fuse , your
expensive speakers can burn out.
Should a fire result, you could find
yourself being held liable for damages.
Use a normal fast fuse between each
supply rail and the output and driver
transistors. This placement is preferable to using one fuse in-line with the
speakers.
If you are using a polyswitch or
MOSFETs in the output, you may decide that it's OK to delete these fuses
but you will still need the fuse in line
with the mains as described later.
For the output transistors, the fuse
value is selected empirically. A good
starting point is to make the fuse equal
to Imax load divided by 3.18.
This size fuse should allow the
amplifier to produce a continuous
sinewave output and allows a bit of
clipping during music. Gross levels of
clipping should blow the fuse.
Use a slow blow fuse in line with
the mains supply. This provides protection if the power transformer, bridge
rectifier or a filter capacitor goes short.
Its value should be:
Fuse (slow blow)= Vee x (Imax load)
X 0.71/240
For my amplifier, that comes out to
about 200mA. Remember to make allowance for power drawn by other
parts of the circuit. For low power
amplifiers, it will be difficult to find a
slow blow fuse near the value you
need. The smallest value you can find
will be OK. In any event, the slow
blow fuse should only operate in response to catastrophic failures.
That's it, finished. You should now
be able to design reliable output stages
for your amplifiers. So go to it.
SC
APRIL 1991
67
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CIRCUIT NOTEBOOK
Interesting circuit ideas which we have checked but not built and tested. Contributions from
readers are welcome and will be paid for at standard rates.
+12V
INPUT
01
470k
01
T
100k
.0
.,.
k
3kHz LP BUTTERWORTH
BUFFER
14
OUTPUT
300Hz HP BUTTERWORTH
BUFFER
300Hz-3kHz
audio filter
A speech filter is often used to cut
the bandwidth in transceivers in order to achieve maximum readability,
or even to do tests on transmitting
equipment. This circuit is a simple
one-IC project and works in the following manner:
Simple IR detector
checks remote controls
This simple tester can be built in a
few minutes and can be used to check
out some remote control transmitters,
as used for TV sets, VCRs and hifi
systems.
The circuit is based on the
GP1U52X Infrared Receiver/Demodulator (IC1) which is available from
Tandy Electronics (Cat. 2 76-13 7) for
about $7.00. It is supplied with a data
IC1a is connected as a unity gain
buffer stage. Its output is passed to a
3kHz low-pass Butterworth filter
based on IC1b, which cuts frequencies above 3kHz at the rate of 12dB/
octave. The signal from pin 7 is then
fed to a 300Hz high-pass Butterworth
filter based on IC1c, which cuts frequencies below 300Hz at the rate of
12dB/octave.
'1
,.
9V :
...L..
i
2
R1
220!2
LED1
vcc
I
GP1 5~2X O/P
1
GND
3
.,.
sheet detailing its features.
When no infrared energy is present, the output of IC1 (pin 1) remains
Another test for IR remote controls
Here's a useful tip for checking baulky IR remote controls. If a control
function is not working, the first step in troubleshooting is to determine
whether the problem lies in the transmitter itself or in the receiver circuit. To
test the transmitter, turn on your AM radio, tune it to a blank spot on the dial
and hold the transmitter next to the ferrite rod antenna. Now press each
control button in turn.
In each case, you should hear a heavily modulated hum or whisle from
the radio and the sounds should all be similar. If the sound produced by the
faulty control function is different (or there is no sound at all), then the fault
lies in the transmitter. Look for faulty switch contacts and if these are OK,
check the encoder IC.
If, on the other hand, the sound produced is similar to that produced
when the other buttons are pressed, the fault probably lies in the receiver.
70
SILICON CHIP
The result is a flat passband from
300Hz to 3kHz with 12dB/octave
slopes on either side of the passband.
IC1d buffers the output so as not to
distort the signal when loaded.
IC1 is a TL074N quad op amp but
an LF347N op amp will work just as
well.
Darren Yates,
SILICON CHIP.
in the Tri-state condition. Rl serves
as a pullup resistor, and the LED is
off. However, when the IC does detect infrared radiation, its output goes
to logic low. This allows the LED to
turn on, to provide a visible indication.
Power for the circuit is provided by
a 9V battery.
To use the detector, ensure an unobstructed path between the IC and
the transmitter or infrared source you
are testing, and keep the distance
between them to 5cm or less. Switch
on the detector and operate the transmitter. The LED will light if an infrared signal is present.
Bill George,
Deception Bay, Qld. ($15)
Editor's note: this device is intendecl for detecting infrared signals
which are modulated at 40kHz. Unfortunately, most infrared remote
controls operate at around 2kHz and
would be rejected by ICl 's internal
filter.
Of cause, the detector may detect a
signal from remote controls at very
close range if the filter is swamped
with excessive signal.
D1
1N4004
D4
1N4004
S2a
IN
+
4700
35VWI LED1
ON
7805
2200 +
16VWJ
GND
01J
.,.
OUT
o---<)+V
01+
.,.
A ~
rov
240VAC
100k
1%
100k
1%
N
E~
D3
1N4004
4700 35VW+
o,l
If you need a dual-rail tracking
power supply in a hurry, then take
a look at this circuit. It uses junkbox parts only and can deliver
voltages up to ±15V and currents
up to 150mA.
The transformer is a 22V 1.5A
centre-tapped type with diodes D3
and D4 acting as half-wave rectifiers to provide unregulated supply
rails of about ±22 volts DC, each
filtered by a 4700µF capacitor.
79 os
OUT
0--0-V
D2
1N4004
202
15V
Bare-bones dual
power supply
S2b
0
IN
These unregulated DC outputs
drive two 3-terminal regulators,
7805 & 7905.
Zener diodes ZDl and ZD2 provide ±15V supply rails for ICl, a
TL072 dual op amp. ICla is connected as a voltage follower. Its
non-inverting input monitors the
output voltage of the 7805 5V regulator via lO0kQ pot VRl. By using
the pot to vary the voltage on the
COM pin of the 7805, we can thus
vary the positive output voltage.
Tracking between the positive
and negative regulators is provided
2200 16VW:r
by IClb which is connected as an
inverting unity gain amplifier. This
op amp inverts the voltage at the
GND terminal of the 7805 regulator
and applies it to the GND terminal
of the 7905 regulator to obtain the
negative rail.
Diodes Dl and D2 provide both
regulators with protection against
reverse voltages which may come
from external loads, while DPST
switch S2 provides the load
switching.
Darren Yates,
SILICON CHIP.
r--------------------------------------•
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SILICON CHIP BINDERS
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These beautifully made binders will protect your copies of SILICON CHIP. Made
with a distinctive two-tone green high-quality vinyl and with heavy board covers,
each binder holds a year's issues (the 14 issues of Volume 1 or the 12 issues of
subsequent volumes).
To order your binders, fill in the coupon on the last page of this issue and send it to
SILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097. Alternatively, phone
(02) 979 5644 and quote your credit card details, or fax your order to (02) 979
6503. Price $Al 1.95 plus $A3 each for postage and packing (NZ $A6 p&p).
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I
~--------------------------------------·
APRIL 1991
71
Two new 100MHz
oscilloscopes from HP
Hewlett Packard has done the unthinkable released its latest 100MHz digital sampling
oscilloscopes with a host of new features but
at a price which directly competes with
analog CRT readout scopes.
By LEO SIMPSON
Until now, digital sampling oscilloscopes have been neither cheap or
easy to use. Their controls have been
generally quite different from those
on conventional analog CROs and
their price has usually been a lot
higher. Now, with the release of the
54600 series oscilloscopes from Hewlett Packard, all that looks set to
change.
The immediate difference between
these new models and previous models fro m the company is that the con-
trol lineup is greatly simplified. Not
only that, it bears more than a passing
resemblance to the control layout on
a conventional analog instrument. For
example, there are knobs for vertical
attenuators, timebase, trace position
and trigger level. None of these knobs
have any calibrations though, as their
settings are shown in the comprehensive CRT display.
The knobs work in exactly the same
way as those on any analog CRO and
their response is instantaneous. This
is quite different from typical digital
sampling oscilloscopes (from HP)
which have a large number of display
modes but which require the user to
step through a number of keystrokes
and screen menus in order to get the
wanted display.
Autoscale button
The best control feature of the lot is
the AUTOSCALE button. This takes all
the frustration out of getting a useful
signal display on the screen. This can
be a time-consuming chore even on
analog scopes. On the HP 54600
series, all you have to do is connect
the probe to a signal source, push the
AUTOSCALE button and the signal is
locked on the screen, together with
the vertical attenuator and timebase
settings. Dead easy.
Unlike analog scopes, the new
100MHz scopes display their waveforms brightly and steadily regardless of sweep speed. They do not
exhibit the flicker or flare that occurs
with analog scopes when displaying
signals at very low sweep speeds.
Instead, they show a trace of constant
brightness, which is gradually retraced, to give the user a visual cue of
the low trace speed.
Also, the faint traces in highly
magnified delayed sweeps can be
viewed without the viewing hood
required with analog scopes. A peakdetect feature enables the new instruments to display complex waveforms,
such as amplitude modulation, correctly. It will catch and display any
glitch that is more than 50ns long,
regardless of the sweep speed settings.
Waveform measurement
While it is a digital sampling oscilloscope, HP's 54600 behaves very much like a
conventional analog instrument albeit with full CRT readout, electronic
graticule and good intuitive "feel".
72
SILICON CHIP
The new scopes have the non-volatile storage and waveform-measurement capabilities that only a digital
sampling system can provide. With
the scopes' two trace memories, signals can be acquired and retained
Seen here is the HP54601A, the four channel version of the new 100MHz
oscilloscope. It is a very compact instrument with a large screen and easy to
use controls.
indefinitely. This allows the user to
make measurements, compare a previously captured signal with a current one, print hard copies or transfer
the data to an external computer for
further processing.
Pre-trigger viewing
Storage also allows pre-trigger
viewing by retaining waveform activity that occurs before the trigger event.
For example, after triggering the scope
on a failure mode in the device under
test, a user can look back in time to
view the events that caused the failure. This is impossible in an analog
scope.
AUTOSTORE mode displays the current waveform at full brightness,
while all previous sweeps are retained
on the display in half-bright, infinite
persistence. With this feature, the
scope can capture infrequent deviations that otherwise would require
constant observation by the user to
determine whether deviations occur.
The design of the new scopes is
based on a new digital architecture
developed by HP. Because the instruments use custom IC processors for
acquisition and display, they do not
rely on the system's CPU to perform
acquisition and display management
functions. For users , these dedicated
processors mean the new scopes have
display-update rates as fast as those
of analog instruments.
Key features of the new oscilloscopes include the following:
100MHz rep.etitive bandwidth on both
the vertical and horizontal axes;
2MHz single shot bandwidth; 2ns/
div to 5s/div range on both main and
delayed timebases; mV/div to 5V/div
vertical sensitivity; 8-bit vertical resolution; automatic setup with a single
keystroke; simple one-button display
storage operations; 16 front-panel
setup memories; two trace memories;
edge, line and TV triggering; 12 auto-
matic measurements of frequency,
time and voltage; dual cursors for
accurate manual time and voltage
measurements ; pushbutton hardcopy
output to plotters and printers via
optional parallel, RS-232 or HP-IB
(IEEE-488) interfaces.
Dimensions are 360mm wide,
180mm high and 300mm deep and
weight is 6.4kg. The 54600 series
scopes come with a 3-year standard
limited warranty with an option for a
5-year limited warranty.
Prices are as follows: HP 54600A
2-channel 100MHz oscilloscope,
$2,395; HP 54601A 4-channel
100MHz oscilloscope, $2,895; HP
54650A HP-IB interface module, $475;
HP 54651A RS-232C interface module , $475; HP 54652A parallel interface module , $275. These prices do
not include sales tax.
We hope to do a detailed review of
the 54600 series in a future issue. In
the meantime, sales information can
be obtained by calling Hewlett-Packard's customer information centre on
(008) 033 821.
SC
APRIL 1991
73
COMPUTER BITS
BY JENNIFER BONNITCHA
Playing with the ANSI.SYS file
This month, we take a close look at the
enhanced keyboard and display device
driver - ANSI.SYS. This is an extensive list
of codes for driver controlling your monitor
screen and keyboard.
ANSI.SYS is a driver which causes
your computer to emulate the American National Standards Institute
(ANSI) standard for terminals. Together with the International Standards Organisation (ISO), these bodies originally established an extensive set of console control codes for
terminals connected to mainframe
computers. The standards provide
software portability for hardware
interfaces.
Note that ANSI.SYS is not a full
implementation of the Digital Electronics Corporation (DEC) terminal
VT-100 control codes. While the VT100 terminal implements all ANSI
control codes, the DOS version of
ANSI.SYS lacks the VT-100 terminal
codes to:
• erase from the current cursor position to the end of screen.
• erase from current cursor position
to the beginning of screen.
• erase from current cursor position
to the beginning of line.
ANSI.SYS recognises a subset of
the control codes defined in the ANSI
console standard.
Before you can start experimenting
with installable device driver
ANSI.SYS, you must explicitly configure your system. The driver needs
to be somewhere on your boot disc,
although it is usually found in the
root or DOS directories. If your driver
is in the root directory, include the
following statement in your
CONFIG.SYS file: device=ansi.sys
However, if your driver is located
in another directory (typically the
DOS directory), include this statement:
device=c: \dos \ansi.sys
Once you include the driver, you
must reboot your system for it to take
effect. It remains installed until you
remove the device line from your
CONFIG.SYS file and reboot the
computer again.
Technically, ANSI.SYS is a console
device driver. It oversees the actions
of the keyboard and screen which are
collectively known as the console.
The program was introduced with
MS-DOS 2.0 and has some 15 sepa-
Before you can start experimenting with
ANSI.SYS, you must configure your system. The
driver needs to be somewhere on your boot
disc, although it is usually found in the root or
DOS directories.
74
SILICON CHIP
rate functions which can be grouped
into five categories:
• control of cursor position;
• erase all or part of the display
screen;
• control video mode settings;
• control video attribute setting;
• reassign character strings to individual keys on the keyboard.
Data entered from the keyboard is
sent to the computer as a sequence of
ASCII (American Standard Code for
Information Interchange) characters.
ANSI.SYS operates by intercepting
special codes sent to the video display and using them to change how
the display and keyboard function.
ANSI.SYS then recognises certain
character sequences as being command sequences which can direct
modification of the display screen
output.
All ANSI commands have the same
format; the command is introduced
with an escape character and a left
bracket. You will often find the word
ESC shown in reference manuals to
represent the escape sequence.
An ANSI escape sequence is a series of characters that you can use to
define functions for MS-DOS. Specifically, you can change graphics
functions and affect the movement of
the cursor. All ANSI.SYS command
sequences begin with an escape character whose ASCII value is 27. The
escape character doesn't display on
the screen, however you will usually
see a left arrow or A(. Either way,
ASCII character code 2 7 is the escape
character and not the Esc key on your
keyboard.
The escape character and the left
bracket are usually followed by a parameter, although there are some escape sequences which can have multiple parameters and some that don't
require any at all.
You can specify multiple parame-·
ters by separating them by semi-colons. Each sequence ends with a letter to indicate the instruction and terminate the sequence. If the function
requires any parameters, they are entered between the [ and the letter. A
typical ANSI code, Esc[2J is the clear
screen instruction. Note that the function code letter is case sensitive - you
need to be careful.
ANSI.SYS escape sequences
The numeric ANSI sequences have
three functions:
• to represent the co-ordinates or
number of columns or lines to move
for cursor positions;
• to represent the mode (such as the
2 in Esc[2J - the clear entire screen
command) for erasing the display or
screen settings;
• to represent the ASCII character of
the extended code for a key when
reassigning the keyboard keys.
ANSI.SYS & cursor position
The most popular use for the commands is to control the cursor's screen
location. Although cursor control is
limited from the DOS prompt, you
can use this type of command in batch
files. You could clear the screen then
position the cursor in the centre of
the screen. Note the appropriate case
for each function code letter.
Cursor position - ESC[#;#H - Moves
the cursor to a position on the display
screen specified by the # parameters.
The first parameter specifies the line
number, the second the column number of the cursor position. The cursor
moves to the home position - upper
left corner of the screen - if none is
specified.
'
Horizontal/vertical position - ESC
[#;#f - Has the same function as the
cursor position command. Again,
with no parameters specified, the
cursor moves to the home position.
Cursor up - ESC[#A - Moves the cursor up a number of lines without
changing columns, where # determines the number of lines moved.
The default is 1. If the cursor is already on the top line, MS-DOS ignores the sequence.
Cursor down - ESC[#B -As for ESC#A
with the cursor moving down the
screen. If the cursor is already on the
bottom line, MS-DOS ignores the sequence.
Cursor forward - ESC[#C - This se-
quence moves the cursor forward one
column without changing lines. The
# sets the number of columns moved,
where the default is 1. If the cursor is
already in the far right column, MSDOS ignores the sequence.
Cursor back- ESC[#D -As for ESC[#C
and the movement is backwards. If
the cursor is already in the far left
column, MS-DOS ignores the sequence.
Save cursor position - ESC[s - Saves
in memory the current position of the
cursor. Cursor position is then restored using the following command,
Restore Cursor Position.
Restore cursor position - ESC[u - This
sequence restores the cursor position
to the value it had when the console
driver received the Save Cursor Position sequence.
Device status report - ESC6n - Requests that ANSI.SYS issue a cursor
position report.
Cursor position report - ESC[#;#R Reports the current position of the
cursor. The first parameter is the current line, the second the current column. ANSI.SYS issues this report in
response to the request for a Device
Status Report.
Erase display - ESC[2J - Erases the
entire display and positions the cursor at the home position.
Erase line - ESC[K - Erases from the
cursor to the end of the line, including the cursor position.
There's much more but perhaps the
obvious has emerged - how to send
the ANSI commands to the screen?
You can't just type the escape character, since when DOS interprets the
Esc key it means erase this line and
start over. Fortunately, you have several alternatives.
The DOS TYPE command
• create a text file using an editor
which lets you enter the escape character just by pressing Ctrl [ (note that
it may appear as either a left arrow or
A[). You can then use the DOS command TYPE to display the file and
activate the functions.
A good trick to remember is that
the escape character is actually Ctrl V
(AV). EDLIN, the DOS line editor, is
quite happy to receive this key sequence. The Ctrl V tells EDLIN to
make the next character in the sequence a control character. Thus, to
enter an escape character, use AV[
followed by the required sequence;
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APRIL 1991
75
TABLE 1
SPECIFY THIS
CHARACTER
$
b
d
e
g
I
n
p
V
TO GET THIS PROMPT
The $ character
The I character
The current date
Escape character (ASCII code 1b hex, 27 decimal)
The
The
The
The
The
> character
< character
default drive
working directory of the default drive
current time
The DOS version number
Carriage return, linefeed sequence. Note this is the
underscore character
eg, AV[[1;37;44m. You must use the
double square brackets [[ since the
first is used with Ctrl V to create the
escape character and the second is
the normal lead_-in sequence for the
ANSI command sequences. When
complete, TYPE filename to see the
results.
The DOS ECHO command
• create a batch file using the above
methods to enter the escape character
and then use the ECHO batch command to activate the functions.
Type the same command above
using:
ECHO AV([1;37;44m
At the DOS prompt, type 't he name
of the batch file then press Enter.
The DOS PROMPT command
• you could use the DOS command
PROMPT to activate the commands,
since the PROMPT code $E is an escape code - and this is possibly the
easiest method . Note that the
PROMPT codes are NOT case sensitive.
Once again, for the same command:
PROMPT $e[1;37;44m
The PROMPT command lets you
change the MS-DOS system prompt
using characters and prompt commands to create special prompts. You
must precede each character with a
dollar sign ($). Table 1 shows the details.
The most popular prompt displays
the current drive and path followed
by the > than sign: PROMPT $P$G.
76
SILICON CHIP
Remember that since the PROMPT
command can send ANSI command
sequences, you can combine the best
of both worlds:
PROMPT $e[1;37;44m$P$G
This tells DOS to change the screen
colour display and make the prompt
show the current drive and path information.
Using BASIC
BASIC shelters the user from the
operating system and thus intercepts
many of the DOS and computer interrupts. The same shelter environment
shields the ANSI device driver. You
could, however, use compiled BASIC
such as QuickBASIC, Turbo BASIC
etc. Clever people can use interpretive BASIC (BASIC, BASICA and GWBASIC) together with the DOS command TYPE to print ANSI sequences.
For example:
OPEN "TEST4.BAT" FOR OUTPUT
AS 1
PRINT #1, CHR$(27);"1;37;44m"
CLOSE #1
The program can then be used by
typing the DOS command:
TYPE TEST4.BAT
With practice, you can gain valuable experience both with your computer and the ANSI commands.
ANSI.SYS escape sequences
The main cursor control functions
are up (A), down (B), left (D) and
right (C). Remember the default is 1,
so used without a parameter, each
command moves the -cursor one row
.or column. You can however specify
the cursor position more accurately:
ESC[5B ... I'm here
This positions the cursor five rows
down the screen, while:
ESC[12;35H ... Now I'm here!
positions the cursor approximately to
the centre of the screen. You could
try these commands using COPY CON
as discussed last month. As a quick
memory jogger, note that each line
ends with the Enter key and you press
function key F6 or AZ (Ctrl Z) at the
completion to copy the console contents to a file:
COPY CON TEST.BAT
<at>echo off
cls
prompt $e[5B ... I'm here
AZ
then
COPY CON TEST2.BAT
<at>echo off
cls
prompt $e[12 ;35H ... Now I'm here!
AZ
MS-DOS 3.3 and 4.x allow you to
suppress the display of a line in a
batch file by preceding the line with
the <at> character. Without the <at> sign,
the ECHO OFF command would display on the screen. Thus, the above
batch files display only what you
need.
Remember to separate multiple
numeric codes with a semicolon and
don't use a semicolon just before the
command letter in a sequence. The
final letter in an ANSI sequence is
the command letter; ANSI does not
see this letter if a leading semicolon
is used; eg, ESC[44;1;37;m is incorrect. Make sure you use the correct
case for the ANSI command letter
since upper and lowercase letters are
significant.
Finally, if you omit a numeric parameter, the assumed value is O (zero)
or 1. Depending on the sequence used,
ANSI makes various assumptions
about missing values. The assumed
value for cursor positioning is 1, while
for screen attributes it is 0. Be aware
that in some situations the default
value may not work and yet in others
will work correctly. If you omit the
row and column co-ordinates from
the ESC[f command, ESC[1;1f (the
home location) is assumed.
Next month, we'll have more adventures with the PROMPT command, setting screen colours and
customising the keyboard.
SC
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AMATEUR RADIO
BY GARRY CRATT, VK2YBX
The Easytune FSK indicator
for HF transmissions
This project was born out of the frustration of
trying to tune various HF data transmission
modes. Initially, the problem was trying to
correctly tune an HF receiver to allow the use
of an automatic CW decoder. Our problem was
that we could hear these signals but couldn't
decode them.
RTTY? Obviously, a switched multitone box was out of the question.
As most RTTY stations feed AFSK
tones directly to the transmitter from
a modem, decoding the two tones,
the mark and the space, had to be
achieved simultaneously. This is also
the case with fax and packet radio
transmissions.
While old timers will no doubt be
shaking th eir heads in dismay, it is a
sad fact of life that not all amateurs
are skilled in the reception of CW.
Knowing this, various manufacturers
produce equipment that is able to
deco de machine generated CW signals.
The device we were using to decode CW signals called for an audio
input of 800Hz plus or minus 80Hz. It
incorporated both an active filter and
a PLL filt er, driving a CPU and associated software, which in turn produced decoded text on a 2-line liquid
crystal display. As any newcomer will
The next consideration was a visual indicator. We needed a circuit that
would activate a LED when the correct tone or tones were received. A
quick check in the data book reveal ed
that an LM567 would do the trick
nicely. We had seen circuits for tone
decoders using the 567 before but
most gave few details.
Fig. l(a) shows the circuit we built,
which worked perfectly first go. The
567 is purpose designed for this task.
Fig.2 shows the internal details of
the 567 tone decoder. It contains a
highly stable phase locked loop with
synchronous lock detection and an
output driver. The centre frequency,
bandwidth and acquisition time are
all determined by external components.
Basically, there are only three components that determine the operating
characteristics of the device. Rl and
Cl determine the operating frequency
of the internal PLL. C2 determines
both the speed and bandwidth of the
device. As can be seen from Fig.3, the
567 has a maximum detection bandwidth of 14%. Using this figure, the
value of C2 can be determined from
the graph. In our case, we wanted
maximum bandwidth detection, so C2
is lµF.
We found that any value greater
testify, accurately tuning the receiver
to produce an audio output of 800Hz
without any audible or visual reference takes some finite time, enough
to miss parts of the transmission.
What was needed was some kind of
indicator.
Initially, we pondered the use of a
fixed 800Hz oscillator driving a loudspeaker, and housed in a small plastic box. It should be simple enough to
hear the beat difference in output fre quency and adjust the receiver accordingly. This would have been fine
if CW was all we wanted to listen to .
But what about facsimile, packet and
120!1
r------ -+- - -+-- - ~~Mh-0 +1 2-15V
+
100
16VW+
LE01
201
8.2V
J
.,.
AUDIO
0. 47
INPUT o---1
3
IC1
567
.,.
VA1
22k
+
1+
+
1+
Fig. l(a): this single tone version of Fig.1 can be used for tuning into CW
transmissions where connection to an automatic Morse decoder is required.
78
SILICON CHIP
IC tone decoder
120\!
100
PARTS LIST
+
LED1
16VWJ
1 PC board, code SC06104911,
77 x 50mm
2 22kQ trimpots, (VR1, VR2)
2 1kQ 0.25W resistors
IC1
567
Semiconductors
2 NE567 tone decoders (IC1,
IC2)
2 red LEDs
2 8.2V zener diodes (ZD1, ZD2)
120!!
.,.
VR1
22k
~t
1
AUDIO ,.____
INPUT ~
100
+
Capacitors
2 100µF 16VW electrolytic
2 2.2µF 16VW electrolytic
2 1µF 16VW electrolytic
2 .068µF metallised polyester
(5mm lead pitch)
2 .01 µF monolithic or metallised
polyester (5mm lead pitch)
ZD2
16VWJ:
8.2V
IC2
567
FSK TUNING INDICATOR
Fig.l (b): this is the version of the Easytune Indicator circuit for FSK detection.
The two 567 tone decoders are set up to indicate the two different FSK tones.
than lµF caused the unit to be too
slow in driving the output. By op erating the chip in the "high input level"
mode (ie, more than 200mV of input
sign al), th e bandwidth chan ges
caused by input signal variation are
eliminated; however, the chip then
becomes sensitive to sub-harmon ics,
as th e input stage w ill be limiting.
By operating the chip in the "low
input level " mo de , best n oise reduction an d out-of-band signal rejection
is achieved, so we determined that
feed ing the input from a low level
source would be the best option.
C3 sets th e b nd edge of the inter-
PHASE
DETECTOR
I
R2
C2
LOO P
LO W- PA SS
FILTER _
3.9k
R1
CURRENT
CONTROLLED
OSCILLATOR
Other data modes
Having sucessfully overcome th e
CW tuning problem, we began to think
of the other interesting HF data
+V
INPUTD---"f-.._--l
V1
n al low pass filter which effectively
attenuates frequen cies outside the
detection band to eliminate spurious
outputs. Th e device is fe d via a 9 volt
zener regulated supply for temperature stability. This also ensures that
the maximum DC voltage of 10 volts
is never exceeded . The output, pin 8,
is the coll ector of an internal trans istor which saturates w h en an in-band
signal is received, an d can sink
100mA if necessary, although not in
our application.
We used the outpu t to drive a LED,
which is our visual indicator.
~
:.! 100kt----'t---t---
I --+---<
;;,
+---+---+---+----l
u
+V
R3
QUADRATURE
PHASE
1 -......-----1
DETECTOR
RL
0
~
~
5:,:
10k t---t---r"'~r"'~t---t---t-----i
~
Vrel
1k .___..___..___..___..___..___.._____,
0
C3
10
12
14
BANDWIDTH (%lo)
0/P
FILTER!
as
Fig.2 : inside the 567 tone decoder IC,
made
Signetics, National Semiconductor and a number of
other companies. It contains a phase lock loop and
a lock detector (pin 8).
Fig.3: the 567 has a m aximum detection
bandwidth of 1 4 %. Using this figure, the
value of C2 can be determined from the
graph. In our case, we wanted maximum
bandwidth detection , so C2 is lµ F.
APRIL 1991
79
f[ C
,,J r.. ,J J
l~
r
300
I
1070 1170 1270
F1S
le F1M
300 387
2025 2125 2225
F2S
le F2M
FREQUENCY (Hz)
3300
,) J
1200
MARK
2200
SPACE
3300
FREQUENCY (Hz)
Fig.4: this diagram shows commonly
used tone pairs for FSK transmissions
and their respective standards.
modes. HF packet at 300 baud, for
instance, uses two tones, 1070Hz and
1270 Hz, which comply to the Bell
103/113 standard. At VHF, the Bell
202 standard predominates 1200 baud
operation and uses 1200Hz and
2200Hz. So we proceeded to build
another tone decoder, feeding both
units with common audio and power.
Fig.1 (b) shows the circuit details.
Construction
A small PC board has been designed for the FSK Tuning Indicator
shown in Figl(b) and this can also be
used for the circuit shown in Fig. l(a).
Fig;5 shows the wiring layout on
the PC board. Install all the parts as
shown, taking care to ensure that all
. '(}~
The PC board can be mounted inside the equipment or installed in a
separate case. Power can come from a 9V battery, via an on/off switch.
polarised components are correctly
oriented.
By pre-adjusting one decoder to
each tone, it became a simple matter
to tune the HF receiver, so that both
LEDs were illuminated when the correct tones w ere being received. Fig.4
shows commonly used tone pairs and
their respective standards.
Alignment is easy. Conn ect a suitable audio frequency counter to pin 5
of the 567 and , ensuring that there is
no audio input connected to the circuit, adjust VR1 until the desired frequency (the same frequency we wish
to detect) is displayed.
No doubt the same technique can
be used for other tone pairs, used for
packet, RTTY and Fax. The unit could
be built into a receiver or enclosed in
a plastic box and fed from the headphone socket of the receiver.
Our unit needed lO0mV to op erate
correctly and this level is easily
achieved through the headphone
socket. In some receivers, it may be
possible to us e the external record
socket, which provides a fixed level
of audio, regardless of the volume
control setting.
This was the case on our Yaesu
FRG7700 lab receiver. The unit could
be powered from a 9 volt battery but
as the current drain is around 20mA,
an on/off switch is recommended.
This is no inconvenience, as once the
signal is tuned, only periodic ch ecks
are required to monitor receiver drift.
References
Signetics Linear LSI Data and Applications Manual, 1985; CQ Magazine, January 1991; The ARRL Handbook.
SC
2.2ue
uF17
0
~ LE
°'u u•
C
.
AUDIO
INPUT
+12· 15V
+
GNO
+
Fig.5: this is the PC hoard wiring
diagram for the FSK versions of the
Easytune Indicator. A single tone
version can be built by leaving out all
the components associated with IC2.
80
SILICON CHIP
Fig.6: this is the full size artwork for the PC board.
I
PRODUCT SHOWCASE
I
Flying-H antenna
has large reflector
AT motherboard
rated at 21MHz
This attractive AT motherboard has
all the features that most 286 computer users could want. It has a
16MHz zero wait state CPU .(21MHz
landmark speed rating), three 16-bit
and three 8-bit expansion slots, two
serial and one parallel printer port, a
Dallas real time clock and an IDE 40-
Amp-hour meter for
lead acid batteries
With the increased interest in
storage batteries for solar power
and electric vehicles, there is now
a growing number of applications
for this amp-hour meter from Av-Comm Pty
Ltd. Based on a microprocessor, the unit
counts the amp-hours
drawn from a . battery
and displays them with
a minus sign. As charging begins, amp-hours
are added until the display reads zero. It automatically compensates
for charging efficiency
and can be zeroed after
a battery is overcharged.
pin connector for a hard disc interface (for adding an embedded hard
disc drive).
It also has an onboard floppy disc
controller and can take up to 4 megabytes of RAM. The only thing you
need to install on the motherboard is
a VGA card. The price? Just $595 from
Rod Irving Electronics, 74 Parramatta
Road, Stanmore, NSW 2048. Phone
(02) 519 3134.
Battery current is sensed with a
precision shunt and it can handle
currents up to 200 amps.
For further information contact
Av-Comm Pty Ltd, PO Box 386,
Northbridge, 2063. Phone (02) 949
7417 or Fax (02) 949 7095.
This unusual UHF antenna has an
H-section dipole backed by a reflector to increase the gain. Claimed frequency coverage is from 420MHz to
960MHz (ie, band 4 and 5) and the
unit can be mounted for reception of
vertical or horizontally polarised signals.
The construction is mainly of black
UV-stabilised plastic with clip-in
black anodised aluminium rods for
the rear reflector. It has an inbuilt
balun and an American style 75Q coax
connector.
It is available from all Jaycar Electronics stores (Cat LT-3180) for $49.95.
Unit converts PC
signals to PALINTSC
Chromatek Advanced Video Laboratory has released the model 9120,
a real time Scan Converter which converts video signals from personal
computers to broadcast quality PAL
or NTSC signals. The scan frequency
range is from 15kHz (CGA) to 128kHz
(high resolution screens).
This enables computer generated
graphics to be used for broadcast
video sources.
The video input signals are measured automatically by the 9120 and if
necessary, it adjusts the conversion
APRIL 1991
81
to achieve the best picture quality.
This allows the user to convert computer images to standard video tape
without having to know the computer's video specifications.
Besides the composite signal for
NTSC or PAL, the 9120 has outputs
for RGB, Y, R-Y luminance/colour
difference signals, and the Y/C signal
for NTSC.
Included as standard features are a
montage circuit for making composite pictures, a gen-lock circuit for
phase matching studio sync signals
and a comb filter for colour cross
checking.
Functions such as chroma keying,
D-1 output and test pattern generators are also available as options.
For further information, contact
Anitech, 52/2 Railway Parade, Lidcombe, NSW 2141.
ATTENTION
AMATEUR ASTRONOMERS
4-channel digital
recorder/announcer
Back in December 1989, SILICON
CHIP published a Digital Voice Recorder Board which caused a great
deal of interest at the time. All sorts
of organisations used the basic design presented there to develop audio
storage units to suit their own applications.
One such product is the Harris 4channel digital recorder/announcer.
It is developed considerably from the
original project and has 4 megabytes
of dynamic RAM to substantially increase its recording time and/or qual-
ity. It can record 4 messages each up
to 30 seconds.
Also included in the unit is a timer
whereby the messages will be automatically played at intervals ranging
from every three minutes up to 30
minutes.
It is intended for applications such
as music on hold, store or phone
announcements, security announcements and PA system feedback eliminator (in instant replay mode).
Recommended retail price is
$799.00. For further information,
contact Altronics Distributors Pty Ltd,
174 Roe Street, Perth, WA 6000. Phone
(09) 328 2199.
We import and sell by Mail Order all types
of Telescopes and Accessories suitable
for astronomical observation and astrophotography.
Because of our vast experience in visual
obervation and astrophotography, we can
best help you to select the right astronomical equipment. That is, equipment that
suits your individual needs and budget.
Furthermore. we do not recommend a
given product unless we have tested it
ourselves or haye enough favourable in-
formation about it from a reliable source
We are glad to inform those who are interested in the very best
in optical,
electronic and mechanical performance,
that we are now the Sole Australian
~
for
the
world-famous
TAKAHASHI astronomical products.
We offer our customers a fast
and efficient service and we
will better any advertised price
on astronomical equipment of
the same brand and quality.
For further information or technical advice
contact:
ASTRONOMY AND ELECTRONICS
CENTRE
P.O. BOX45
CLEVE, SA 5640
Phone (086) 282 435 Anytime
82
SILICON CHIP
Bose Lifestyle System Winner
As announced in the March 1991 issue, Mr Stuart McDonald of Warners
Bay won the Bose Lifestyle Music System which was the major prize in our
subscription drive last year. Pictured above is Stuart MCDonald (at left)
being awarded his prize by Paul Trimble, manager of Charlestown Hifi.
Charlestown Hifi is a specialist hifi dealer serving the Newcastle, Lake
Macquarie and Hunter regions. Congratulations Stuart.
April bargains
will save you $
from Sheridan's
ARLEC AC/AC ADAPTOR
These are 6VAC and 3 Ahr and are
approved. What a bargin
ONLY $9.95
Travelmate 2000 notebook
computer has 286 CPU
The Travelmate 2000 is based on a 12MHz 80C286
processor with one megabyte of DRAM (expandable to 3
megabytes). It comes with a 20 megabyte hard disc, a full
function keyboard and has a triple supertwist LCD black
on white VGA display.
The 254mm display uses cold cathode fluorescent side
lighting to provide crisp images. It is claimed to be ideal
for running Windows or other graphics intensive software.
Standard features comprise a Centronics parallel interface, RS-232 serial port and an expansion port. Optional
features include a numeric keypad interface, 1.44MB
floppy drive and CRT interface. Battery watch software
enables the user to check the battery status at any time.
Recommended retail price is $5250 plus sales tax where
applicable. For further information, contact the Marketing Manager, Data Systems Division, Texas Instruments
Australia Ltd, 6-10 Talavera Road, North Ryde, NSW
2113. Phone (02) 878 9000.
Spaced out
TV from
Philips
If you're sick of the
sameness of today's
TV sets with the black
rectangular cabinets
then consider this
new model which is
styled in the form of a
space helmet and finished in Monza red.
Flipping up the visor
reveals a 14-inch dark
glass screen. It has an on-screen digital display to show
control functions such as programming, volume, picture
and timer. It comes with an infrared remote control, also
finished in Monza red.
The set may be viewed with the visor up or down and
may be tilted for the best viewing angle. The price of this
piece of whimsy? $699 from your nearest space appliance store.
SC
8 LINE DOT MATRIX DISPLAY
Included with this display is the driver necessary
and also a data sheet to get you started. There
is only a limited quantity so be quick
ONLY $39.95
ELECTRO$
4.5" 230/240V
FAN
Ball bearing type
These come in three types
2200uF 35V
$1.20 each
These are quality
new fans and
10,000uF 16V and the
470uF 200Vare
only
$2.50
each
only
$14.50
These quality Hitachi displays come complete with the
driver and have a 128 x 480 dot matrix display. Uses LM215
~
Includes data sheet
OUR PRICE $45.00
-·
"'
-
Mi;~""
lllllsr
<,
Mlnature Toggle
switch
This one has hundreds
of uses and we have a
bulk load of them.
SURRY HILLS, NSW, 2010
TELEPHONE: (02) 281 7727
.
"'
~"
::1
These can be used in mains
filter projects and have a
rating of 5 AMP, 50/60Hz.
Grab a couple just in case.
ONLY
$2.95
I
SHERIDAN ELECTRONICS,
328 ELIZABETH ST,
.
(Cnr Klppax St. opp. Central
Station & Dental Hospital)
<
Potter 250V
Mains Filter
10 FOR $6.00
While stocks last
,~
Ud
SHOP HOURS:
MON-FRI
SAT
9.00am- 5.30pm
9
12
.30am • .00pm
APRIL 1991
83
.
~
\\ .
2&4WAY
RS232 DATA TRANSFER
SWITCHES
If you have two or lour compatible
devices that need to share a third or
fifth, then these inexpensive data
t~ansfer switches will save you the
time and hassle of constantly
changing cables and leads around.
• No power required
• Speed and code transparen1
• Two/Four position rotary switch on
front panel
• Three/Five interlace connections
on rear panel
• Switch comes standard with
female connector
THl;:BUTTON
SPIKE PROTECTOR
Surges and spikes are caused not
only by lightning strikes and lo_ad
switching but also by other equIpmen1
being switched on and off , such as
fluorescent lights, electr!c motors,
fridge freezers, air cond1honers, etc.
A simple way of monitoring RS232
interface lead activity. Interlace
powered, pocket size for circuit
The Fortran CPF Filtered Electronic
Spike Protector provides a protective
electronic barrier for microcomputers.
printers. telephone systems and
modems electronic typewriters,
audio and stereo systems and other
sensitive electronic equipment.
The CPF provides protection from
dangerous electrical spikes that can
cause anything from obvious damage
(like immediate equipment failure) to
less obvious harm that can drasticaUy
shorten a system's life.
CPF's superior circuitry design and
semi conductor technology responds
instantly to any potentially damaging
over-voltage, ensuring safe trouble
free operation.
, Additionally. CPF's filtering capability
helps elimmate trm •blesome and
annoylng interference, general hash
cre_ated by Small motors, fluorescent
lamps, and the like that threaten the
performance and shorten equipment
life of unprotected electronic
components.
SPECIFICATIONS:
Electrical rating: 220-260 volts
(AC) 50Hz 10 Amp
Spike/RF! Protection: 4,500 amps
for 20m/second pulses
Mavlmum clamping voltage: 275V ·
ditferemti:ti mode.
Cat.X10088 ........ $69.95
\~~~~arg:~~j~9 ~~g~a~~~ing.
2 spares 24 switches enables you
to break out circuits or reconfigure
and patch any or all the 24 active
positions.
For effective protection such spikes
must be ~topped b_efore they reach
~~;o~9~~~~~J!~f~~~ ~Tn~~~tect
1
SPECIFICATIONS:
Connectors: 0825 plug on 80mm
ribbon cable and 0825 socket
Indicators: Tricolour LED's for TD .
AD, RTS, CTS, OSR, CD, TC
all equipment plugged into a~1acent
outlets on the same branch circuit
The Button employs unique metal
oxide varister technology and will
dissipate 150 joules of electrical
energy. (nearly twice that of
comparable surge arresters.)
AC. DTR, (E)TC .
Jumper Wires: 20 tinned end pieces
Power: Interface power.
Enclosure: Black, high impact
plastic
Dimensions: 85 x 95 x 30mm
..... $42.95
_ _ ___ _ _______ _ __
,
Q
·...
.
COMPUTER PAPER
Quality paper at a low price! 2,000
•
$39.95
-~ I
I
1'
1l
ROD'S COMPUTER
Jl
TIPS!
UV EPROM ERASER
Erase your EPROMs quickly andsafely. This unit is the cost
effective solution to your
problems. It will erase up to 9 x
24 pln devices in comp.lete
safety, in about 40 minutes (less
time for less chips)
• Chip drawer has conductive
foam pad
• Mains powered
• High UV intensity at chip
surtace ensures EPROMs are
thoroughly erased
!Are you having trouble
KEYBOARD
EXTENSION LEAD
: reading 5 1/4" disks which
I have been around your
• Keeps your paper and prmt-outs·
5 Pin Din plug and socket .
I children or non-computer
neat and orderly
P19038 ................... $9.95 : people? This is a common
• Transparent cover makes 11 easy
to check on paper supply
fingerprint problem. Arm
• Paper can be fed from the centre
or the rear according to the design
1 yourself with a bottle of
of the printer
1 methylated spirits and
• Removable drawer which allows
paper to be changed without
cotton wool balls. Hold the Without timer
moving the printer
• Retractable rear basket makes
disk that wont read up to
X14950 ..................... $99
print-out collection fast and
convenient
the light and try and spot
With built-in timer
• Suitable fo r mos1 printers
the fingerprint, grease or
. X14955 .................. $169
$69.95
foreign matter. You do this
by looking in the "window·•
DUST COVERS
DELUXE PRINTER STAND at the media and slowly
I
• ~~~~~~~i~~~~i~l~~t~:~~~i;ea
turning the disk with your :
nd
• ~;;g;iit~~;~'t~~sa~~~1f;.u er
fingers in the middle hole. I
• Adjustable paper deflectors
Be v~ry careful not to
:
0
;i;;tFcaper
crease the disk. You might I
0
~;~::~~~ ~ 7uo~~~rinters$
1
0
69 _95 have to clean both sides of ;
DATALIFE DL-600
~ the disk at the problem
I
DATA CARTRIDGE
position(s), but normally
1
Stores up to 120 M/Byte
you can recover your
1
C12614 ............. $59.00
software by this
DUST COVER
1
ENCLOSED PRINTER
STAND
j
·,,
only$49
onlY$59
2WAY {X191
sheets of 70 gsm bond paper
~
Star, and many other printer
~N~u~~~~e::quired
• Speed and code transparent
• Two/Four position rotary switch on
front panel
• Three/Five interface connections
on rear panel
• Switch comes standard with
female connector
• Bale locks are standard
.
Cal. C21003 11 x9 112··
$39
$49
Save time·and hassles of constantly
changing cables and leads around
with these inexpensive data transfer
switches. These data switches
support the 36 pin centronic interlace
. used by Centronics, Printronics,
Data Products, Epson, Micronics.
~6:~~lt~ir!~VR~~~tf~o Joules
Response Ti me : 1Ons
Protection Level : 350V peak
r'
only
only
2&4WAY
CENTRONICS DATA
TRANSFER SWITCHES
SPECIFICATIONS:
X15700 .............. $99.95
g
2 WAY Cal.X19120
4 WAY Cal.X19125
XT HD CONTROLLER ...,$1 29
AT HD CONTROLLER .... $199
RS232/SERIAL
CLOCK. ................•..•........ $49
MONO COLOUR CARD .• $76
MULTI 0~ ......................... $99
512K RAM........................ $59
DIAGNOSTIC........•........•. $795
TTUPRINTER. ................. $89
RAM 2M AT EXT/EXP. ..... $225
SM AT EXT/EXP............... $325
FAX CARD ....................... $595
4 PORT SERIAL ............. $129
VGA 256K ........................ $179
VGA 512K ........................ $219
VGA 1MEG ...................... $249
VOICE MAIL.. .................. $199
PRINTER CARD ............. $29
EGA CARD ...................... $149
• ~~~u;~i5~gi,~:~
2 WAY FDD CONT
(360K) .............................. $39
RS2321SERIAL <:ARD ..... $39
GAMES CARD ................. ~29
AT SIP/G 1 SIPIG ............. $43
AT S/P/G 2 S/P/G ............. $49
4 WAY FDD CONT.
(360-1.44M)...................... $129
2 WAY FDD CONT.
(360-1 .44M)....................:. $80
CLOCK CARD ................. $39
SMART DRIVE
ADAPTER IDEIFDC........ $89
SMART DRIVE
AO APTER mE 110 FDC... $119
:
•High quality ABS plastic and
anti-static rubberised lop
•Stationary holder
•Includes pull-out sheH for
I this problem!!!
1
I
Regards Rod Irving. I c 21066 •·················$ 14 ·9 5
.L .________________ .J AT' Cover Set
C21068 .................. $16.95
Mouse
LEADS
RS232 GENDER
CHANGERS
• Saves modifying or replacing
non-mating RS232 cables .
• All 25 pins wired straight through
Cat X15650 Male to Male
Cat. X 15651 Male to Female
Cat X 15652 Female to Female
'Normally $14.95 each
Onlv$8.95
DISK NOTC:HF.R
Converts 5 1/4" single sided
noppy disks to double sided , by
placing an appropriate notch
in the floppy disk jacket.
c2107o .................. ss.oo
Stanmore.
RS232 MINI TESTER
• Male to female connections
• All pin wired straI1=1hl through
• Dual colour LED indicates activity
and direction on 7 lines
• No batteries or power re quired
T.D . Transmit Data
D.S.R. Data Set Ready
A.O. Receive Data
C.D . Carrier Detect
A.T.S. Request to Send
D.T.A. Data Terminal Ready
C .T.S. Clear fa Send
Cat. X15656 . . .. Normally $39.95
SPECIAL. ONLY $32.95
2048.
Phone (02) 519 3134
Fax (02) 519 3868
MELBOURNE , 48 A·Beckett St
Phone (03) 663 6 t 51
NORTHCOTE: 425 High St.
Phone. (03) 489 8866
CLAYTON : 56 Renver Rd .
Phone (03) 543 7877
MAIL ORDER&
CORRESPONDENCE:
P.0 ..Box 620, CLAYTON 3168
Order Hotline: 008 33 5757
(Toll free, strictly orders only)
Inquiries: (03) 543 7877
Telex: AA 151938
Fax: (03) 543 2648
MELBOURNE DEALERS
MICRODOT
177 SPRINGVALE.ROAD
NUNAWAOING. Ph.894 1255
GREENSBOROUGH
accessories free of dust and
-I children I am very aware of I grime while not In use
A working bench tor your Mouse.
.
XT* Cover Set
1
1
Only $24.95
SYDNEY ·: 74 Parramatta Rd.
Keep your computer and
.
procedure. Having young
.
Normally $33.95,
RODIRVING
ELECTRONICS
l
MAGIC STAGE
CENTRONICS GENDER
CHANGERS
• Female to Female.
• Saves modifying or replacing
non-mating Centronics cables.
• All 36 pins wired straight through.
Cat. X15663 Male to Male
Cat. X15661 Male to Female
Cat. X15664 Female to Female
H EAD CLEANER DISKS
It only takes a minute amount
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COMPUTERS
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• 3 1/ 2"
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• D837 Male to 34 way edge
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• Length 0·5 metres
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Parellel model: MP-201
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I
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•
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~*
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Remove ugly paper feed edges
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\
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Errors and omissions excepted.
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..
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Range: 300 feel In open field
P105SO
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,., ,,.,
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24 pin .... 35e
28 pin .... 451
40 pin .... 45C:
...
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,...
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Output level: 37mV(max)
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I
SUPER HORN
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Requires no crossover and
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· Sensitivity: 100d8/ 0.5 m
Frequency response :
~
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Normally
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~~~,
••
.
SPEAKERS
REGULATORS
DC FANS
80 l 80 l 25.4mm
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H10112..... s5.75 ·s5.25
•130x68x41mm
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•83x54x28mm
H10115..... $2.25 $1.95
• 120 x 65 x 38mm
H10120 ..... $2.DS $2.50
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P12167 $2.95 $2.50 $2.00
IDC CENTRONICS 36
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H10111 ..... $4.95
Z10140(R)
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010520 MU45 O·lA
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Transmitting Frequency:
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~
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1-9
MICROPHONE SPECS:
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Save• small fortune on these
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·Transmitter 1-9
1-9
( CRYSTAL LOCKED
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MICROPHONE &
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pulsed or used in a
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CANNON TYPE 3
PIN CHASSIS
MALE
LEDS
Errors a
, Prices an speci
ica
change.
IBM.
pc· xt·
AT· ilf9 189'St11,
lntem1tion11 Bus ,neu Mach,
,eg,sierld tr l0e/Tll111 •
:11dm1nr.sot the,1 respec1ove
REMOTE CONTROL
BY BOB YOUNG
How pulse code modulation
decoders were developed
Of all the units that comprise the modern
radio control set, the decoder has probably
undergone the most circuitous development.
Where many discrete components were once
required, it can now be done in one or a
couple of ICs.
As I have pointed out in the past,
when the new generation of PCM sets
were launched onto the marketplace,
accompanied with the usual hoopla,
much was made of the fact that PCM
was fitted with "Fail-Safe".
Amid many gasps, oohs and aahs,
the unsuspecting modern generation
of the modelling fraternity eagerly
embraced PCM, as do all fraternities
eagerly awaiting their next technological "fix".
This appears to be the problem
when dreams become reality, the reality fades quickly and a jaded technological palate seems to require
constant boosts of new technology. If
only people stopped to soak up the
wonder of all of this technology we
are surrounded with, they would be
much more satisfied with what they
have.
However, not all of the modelling
fraternity eagerly embraced PCM. The
CLOCK
RESET
CH1 OUT
CH20UT
CH3OUT
CH4OUT
fl____________________.r
_Sl___________________
- -n~ - - n _ __
_
____.
.....__
Fig.1: repeated from last month, this diagram shows the essence of the
serial to parallel conversion performed in the decoder. The serial pulses
from the receiver are converted into control pulses for the servos.
86
SILICON CHIP
greenhorns may have, but us old timers recognised it for what it was; a
recycled version of the system that
by 1964 had become known as "that
circuit which neutralised the controls
on the way to a crash". PCM has become one of the sad stories in the
development of R/C systems. However, I digress.
The modern digital proportional
system grew by a tortuous process
and progressed through all sorts of
developmental periods, amongst
which were pulsed multi-tone systems. These systems came close to
giving good results but the technology for tone decoding did not exist in
those days (late 1950s). I still look at
the multi-tone system with interest
and with the new technology, I feel
there is potential for a much more
interference free system here. However, that is for the future; our story is
about the past.
In the early 1960s, Don Mathers
and Doug Spreng developed the first
really successful digital system and
it completely revolutionised model
radio control. Gone were the days of
constant retuning, bulky audio filters
and poor response times.
The Mathers and Spreng system
delivered tuning-free control with a
maximum response time of 16 milliseconds and almost perfect proportional control. The greatest benefit
howe.ver was that all controls were
simultaneous . Gone were the days of
manually pulsing alternate controls.
The modellers of the day were in
raptures. Here was genuine progress
and the marketing men had a field
day, and for once I did not mind. I
was in there helping them. Real progress I am all in favour of.
However, the first generation de-
however, and the second generation
sets allow the owner to select FailSafe or leave it off.
They even allow choice of PPM or
PCM modes. The Germans have a
quaint way of expressing the situation; they state that Fail-Safe PCM
allows you to "crash like a gentleman". If you have one of these modern sets, select PPM and no fail-safe.
The results are well worth the effort.
Personally, I feel that a more productive approach to PCM and microprocessor systems would be in error
detection and correction as in CD
technology, leaving Fail-Safe out
completely. This would represent, to
my mind, a valid application of
technology.
Circuit techniques
The Bonner Digimite was quite advanced for its time but incorporated the FailSafe concept. If the incoming pulse train was corrupted, the decoder was shut
down and a neutralising DC level was sent to the wiper pads in the servos. The
throttle was set to low and controls to neutral.
coders had the dreaded "Fail-Safe"
built into the system. In retrospect,
the "Streakers Defence" applied in
this case. It did seem like a good idea
at the time and I can remember being
very impressed with the concept. In
those days many of us were still flying
what were virtually free-flight models with a very high degree of natural
stability built in.
If the radio failed, and they did fail
more often in those early days, the
model kept flying by itself. The motor
was cut by the Fail-Safe and all one
had to worry about was the odd thermal which carried off many a model,
never to be seen again.
Keep in mind also that our old
friend "V2 " is a component of kinetic
energy and cutting the throttle is very
important as it reduces crash damage
considerably. It still does and I am all
in favour of Fail-Safe throttle even
now. My real objection to Fail-Safe is
in the locking out of the controls once
Fail-Safe is activated.
However, and here is the crux of
the story, by 1964 modellers had discovered the neutrally stable aerobatic
aircraft and now we have a vastly
different story. Neutralised controls
on this type of model are a death
sentence, hence the epithet above.
These things flew as straight as an
arrow in the direction of the last control command and once control was
locked out, crash they certainly did.
It did not take long for the designers to wake up to the fact that some
control was better than none, thus
Fail-Safe was consigned to the rubbish bin and models were allowed to
fly through interference or weak levels of RF until control was regained
properly. The odd snatch of control
available in the noisy periods was
often enough to keep the model flying.
The problem with Fail-Safe is that
once the decoder decides that the
signal is unreadable and shuts itself
down, all control is lost until the
decoder deems it proper to restore it.
I personally dislike having electronics decide. for me when I can or cannot have control of my model.
Fail-safe is an invalid concept in
theory, proved itself invalid in practice and was quite correctly consigned
to the rubbish bin; that is, until the
new generation of university trained
designers were turned loose into the
practical world and dragged it out
again in the form of the PCM set.
Even these people learned quickly,
The first really successful commercial proportional system appeared
around 1964 in the shape of the Bonner Digimite and featured, for those
days, absolutely revolutionary ideas.
They were heady days for modellers
and I can still remember the excitement generated by the American advertising.
Bonner was a leading manufacturer
of servos for use in reed receivers and
when he went to a proportional system he spared no expense to make it
the best available and it was. It gave
good service to many people for many
years - quite an achievement for a
pioneer set.
It did, however, feature Fail-Safe
which was a pity, but there was little
known about this concept in those
days.
Bonner followed the Spreng and
Mathers concept in which a serial
stream of pulses are transmitted to
the receiver and then passed to a serial to parallel converter for decoding. Fig.1 (repeated from last month)
shows the timing sequence for this
serial to parallel conversion.
The system is termed Pulse Position Modulation (PPM) and in this
system a master clock in the transmitter triggers a cascaded series of
pulse generators. Each of these generates a pulse, the width of which is
controlled by the potentiometer
coupled to the transmitter control
stick. Convention has this width at
1.Sms for neutral; lms for minimum
and Zms for maximum pulse width.
Depending upon the number of
channels (controls), a set will have
APRIL 1991
87
CH2,3,4,5
CH1
.005
CH6
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1N914
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HAST STAGE ONLY
I
REPEAT FOR
EACH CHANNEL
Fig.2: this serial to parallel decoder is based on BRY39 silicon controlled
switches, one for each servo channel. The circuit was simple yet reliable & was
used for many years until IC decoders appeared on the scene.
from two to eight pulse generators.
These serial pulses are then converted
into a marker pulse stream in which a
350µs marker pulse marks the beginning and end of each pulse.
Transmission is continuous, with a
new frame transmitted every 16-20ms
(new clock pulse). Thus, in a 4-channel set with a frame rate of 16ms, full
deflection on all controls will result
in a data stream 4 x 2ms long followed by a resting period of 16 - 8ms
or 8ms. This rest period is used as
an identification or synchronisation
pause.
This serial data stream may be
transmitted by NBFSK or amplitude
modulation and the receiver passes
on a duplicate of this data to the decoder. The decoder is essentially a
serial to parallel converter and there
is a wide varity of approaches 'to the
decoding process. However, all follow the Spreng and Mathers concept
of reconstituting the serial stream to
the original number of variable width
pulses which are essential for the
operation of the proportional servo
(described last month).
Bonner used an 8-transistor array
in a Johnson ring counter, with a diode matrix for decoding. Frame validity was verified by a separate
counter. Bonner went the whole hog
and came out with an 8-channel set
and decoding alone took 15 transistors. If the incoming pulse train was
corrupted, the decoder was shut down
and a neutralising DC level was sent
to the wiper pads in the servos. The
throttle was set to low and the controls to neutral.
As you can imagine, this was quite
an elaborate circuit for discrete corn-
A_ _ _ _ _ _ _ _ _ _ _ _ _.___ _ _ _~_
_..._ _ _ _ _ _.___ _ +4.8V
14
B
12
68k
.,.
IC2
74C164
6
10
11
12
13
.,.
Fig.3: this circuit used a 74C164 serial to parallel decoder & is still current
today. However, many manufacturers are now going over to custom ICs which
enable them to incorporate more features.
88
SILICON CHIP
ponents and the set was a little bulky.
The problem with this system was
that corrupt data was often encountered and the set immediately went
into lock-out until valid data was
again established, thus denying the
pilot access to the controls. Quite often this corrupt data was only present just long enough to activate the
Fail-Safe.
Once activated, the pilot had to wait
out the time-out period, thus the FailSafe exaggerated what was in reality
a very minor glitch - one that the pilot
may not have noticed under normal
conditions. He certainly noticed the
throttle come off and the controls fly
back to neutral and stay there, even if
it was only for a very brief time. But
at 100km/h, even a very brief time
can be disastrous.
The lessons learned from this system and many others were quickly
picked up , and the second generation
systems came out without Fail-Safe ,
the concept being that it was better to
let the model fly through the corrupt
data. The era of truly reliable radio
control modelling had begun. Bonner
never learned the lesson and stuck
with Fail-Safe and gradually faded
from the market.
Decoder development followed
quickly from there on and there were
many ingenious circuits, all aimed at
improving reliability and reducing
component count. This in turn gave
smaller size and lighter weight.
One very popular circuit was that
shown in Fig.2. The heart of this was
the SCS (silicon controlled switch).
One switch was used per channel and
the pulses just simply stepped
through the counter. The output was
a positive pulse whose width equalled
the distance between the leading
edges of the clock train. Simple and
reliable , this circuit was used until
the IC decoder began to appear.
The IC decoder had a patchy beginning and was usually cobbled together
out of a number of chips. JK flipflops
were a popular item and in 2-channel
sets the 4013 dual-D flipflop is still
used extensively.
The problem with using several IC
chips is that they are expensive in
regards to board space and size is
always a problem in R/C receivers.
This was particularly true in the days
before surface mount devices. Three
14-pin DIP packs would use all of the
space available and thus IC decoders
were seen to appear in one manufacturer's equipment while others stuck
with the SCS or discrete decoders.
The most usual reason in those days
for going to ICs was just simply to
hop on the bandwagon.
Then the serial to parallel decoder
made its very welcome appearance.
Here was a single chip solution and
chips such as the 74C164 would give
8 simultaneous controls in a single
chip. Fig.3 is a circuit of a decoder
using this chip. It is part of the circuit
featured on page 111 of the December
1990 issue. The 74C04 is used as an
This modern radio-control transmitter
uses pulse code modulation (PCM)
techniques to provide simultaneous 7channel control. Other features
include channel mixing, dual rate
control, trim adjustment & servo end
point adjustment.
audio amplifier/shaper/inverter.
Briefly the circuit in Fig.3 works as
follows . Transistor Q5 is used as a
small signal amplifier with a slicing
action. Thus, low level noise is eliminated and the amplified pulse train is
passed on to the 74C04. This acts as
Mailbag - continued from page 5
"Much more expensive to repair":
how do you look at the modulation
on an FM Tx? Answer: with great
difficulty or use a modulation meter.
Quoting my own case, having manufactured AM sets for many years,
suddenly my test equipment was inadequate.
There followed a spending spree
on new test equipment which included a modulation meter, a more
elaborate signal generator and a more
accurate frequency counter, amongst
other things. Then followed a stock
of more expensive crystals and other
components, and believe me broken
crystals are a big item in R/C receivers. Add to this a more elaborate alignment procedure. Need I go on?
"Much more expensive and sometimes more difficult to change crystals in": this is a very important practical consideration. Quoting from the
Futaba (Aust.) price list again: AM
crystals, $24.95 per pair; FM crystals,
$38.50 per pair. Because of the narrow bandwidth of some FM sets, crystal tolerances can put the frequency
outside the passband with a loss of
range occuring. Moral - always check
the range after crystal changes.
Complexity covers more than component count and includes alignment
which we have already covered. The
"simple AM receiver" was included
as a bit of history to illustrate the
development of narrow band spacing
without elaborate ceramic filters. I did
point out that it was a 20-year old
design. A modern AM receiver using
ICs in the RF section (as do the FM
examples you gave) would present a
much lower component count. The
question is would they work any better and the answer is probably not.
Capture effect was the weakest
statement in the article and probably
should not have been included. But
an inverting and squaring amplifier
to provide the necessary pulse information to the 74C164.
The output of pin 2 is the clock
stream and is applied to pin 8 of the
74C164 . Pin 4 of the 74C04, D3 and
the .033µF capacitor comprise the
identification network or sync separator. Pin 6 of the 74C04, D4 and the
2.ZµF capacitor comprise the chip
enable network. This network filters
the incoming pulse train and sends
the chip enable (pin 9) high. Thus,
the chip is disabled if there is no
incoming pulse train. This prevents
random noise from damaging the servos by driving them hard up against
the end stops.
The timing still follows the broad
outlines of Fig.1.
This type of decoder is still viable
today for PPM, however the larger
manufacturers have begun to move
over to custom ICs which incorporate
several features not found in off-theshelf decoding ICs.
Such features as voltage regulation
and noise filtering are often built into
the decoder chip, thus reducing even
further the component count.
The really significant development
in decoding, however, has been in
the area of the microprocessor and
here there is great promise for the
future.
SC
as you point out, it is laboratory demonstrable and I do seem to remember a series of editorials in RCM&E
some years ago on "Pirated models
due to capture effect". Actually, I
thought I was being very fair in the
article as I gave pros and cons for
both systems.
The remarks on oscillator design
were virtually a direct quote from my
friend who checked the article. I had
forgotten to mention the supply rail
stabilisation and he pointed this out
to me. All of these remarks I heartily
endorse. I did not say design was
impossible but that NBFSK placed
"more stringent demands on the designer". I stand by these remarks. All
of the NBFSK oscillators I examined
had zener stabilised supply rails and
heavy decoupling. I have yet to see an
AM transmitter with a zener stabilised oscillator.
Bob Young,
Silvertone Electronics,
Riverwood , NSW.
APRIL 1991
89
Silicon Chip
BACK COPIES
May 1988: Optical Tachometer For Aeromodellers; High Energy Ignition For Cars; Ultrasonic Car Burglar Alarm; Walkaround Throttle
For Model Railroads, Pt.2; Designing & Building RF Attenuators; Motorola MC3334P High
Energy Ignition IC Data.
July 1988: Stereo Control Preamplifier, Pt.2;
Fitting A Fuel Cut-Off Solenoid; Booster For
TV & FM Signals; The Discolight Light Show,
Pt.1; Tone Burst Source For Amplifier Headroom Testing; What Is Negative Feedback,
Pt.3; Amcron MA-1200 Power Amplifier Review; Amplifier Headroom - Is It A Con?
August 1988: Building A Plasma Display; Universal Power Supply Board; Remote Chime/
Doorbell; High Performance AC Millivoltmeter,
Pt.1; Discolight Light Show, Pt.2; Getting The
Most Out Of Nicad Batteries; Data On Insulated Tab Triacs.
September 1988: Hands-Free Speakerphone;
Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Vader Voice;
Motorola MC34018 Speakerphone IC Data;
National Semiconductor LM12 150W Op Amp
Data & Appl ications; What Is Negative Feedback, Pt.4.
October 1988: Stereo FM Transmitter (Uses
Rohm BA1404); High Performance FM Antenna; Matchbox Crystal Set; 'Electronic House
Number; Converting A CB Radio To The 28MHz
Band; Queensland's Powerful Electric Locomotives.
Computer Sound Repeater; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cassette Players; Massive Diesel Electrics In The USA; Marantz LD50 Loudspeakers .
November 1988: 120W PA Amplifier Module
(Uses Mosfets); Poor Man's Plasma Display;
Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten
The Fan In Your Computer; Screws & Screwdrivers, What You Need To Know; Diesel Electric Locomotives.
February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System; LED Flasher
For Model Railways (uses LM3909); Build A
Simple VHF FM Monitor (uses MC3362), Pt.1;
Lightning & Electronic Appliances; Using Comparators to Detect & Measure .
December 1988: 120W PA Amplifier (With
Balanced Inputs), Pt.1; Diesel Sound Generator; Car Antenna/Demister Adaptor; SSB Adaptor For Shortwave Receivers; Electronics &
Holden's New V6 Engine; Why Diesel Electrics Killed Off Steam; Index to Volume 1.
March 1989: LED Message Board, Pt.1; 32Band Graphic Equaliser, Pt.1; Stereo Compressor For CD Players; Map Reader For Trip
Calculations; Amateur VHF FM Monitor, Pt.2;
Signetics NE572 Compandor IC Data; Electronics For Everyone - Resistors.
January 1989: Line Filter For Computers; Ultrasonic Proximity Detector For Cars; Simple
April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know
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SILICON CHIP
Cost Dual Power Supply; Inside A Coal Burning Power Station ; What To Do When Your
Computer Goes Bung, Pt.3 ; Digital Waveform
Generation Using A Computer, Pt.4.
August 1990: High Stability UHF Remote
Transmitter; Universal Safety Timer For Mains
Appliances (9 Minutes) ; Horace The Electronic
Cricket; Digital Sine/Square Wave Generator,
Pt.2 ; The Tube Vs. The Microchip (Two Shortwave Receivers Compared) ; What To Do When
Your Computer Goes Bung , Pt.4.
September 1990: Music On Hold For Your
Telephone; Remote Control Extender For
VCRs ; Power Supply For Burglar Alarms; LowCost 3-Digit Counter Module ; Voice Mail For
Your Computer; Simple Shortwave Converter
For The 2-Metre Band ; How To Make Dynamark Labels.
About Capacitors ; Telephone Bell Monitor/
Transmitter; 32-Band Graphic Equaliser, Pt.2 ;
LED Message Board, Pt.2 .
May 1989: Electronic Pools/Lotto Selector;
Synthesised Tom-Tom ; Biofeedback Monitor
For Your PC ; Simple Stub Filter For Suppressing TV Interference ; LED Message Board, Pt.3;
Electronics for Everyone - All About Electrolytic Capacitors.
June 1989: Touch-Lamp Dimmer (uses
Siemens $LB0586); Passive Loop Antenna
For AM Radios ; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3; Coherent CW - A New Low
Power Transmission Technique .
July 1989: Exhaust Gas Monitor (Uses
TGS812 Gas Sensor) ; Extension For The
Touch-Lamp Dimmer; Experimental Mains Hum
Sniffers ; Compact Ultrasonic Car Alarm ; NSW
86 Class Electric Locomotives ; Facts On The
PhaxSwitch - Sharing Your Phone Line With A
Fax Machine.
August 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser, Pt.1; Garbage Reminder· A 7-day Programmable Timer; Introduction To Stepper
Motors; GaAsFet Preamplifier For The 2-Metre
Band ; Modern 3-Phase Electric Locomotives.
September 1989: 2-Chip Portable AM Stereo
Radio (Uses MC13024 and TX7376P) Pt.1 ;
Alarm-Triggered Telephone Dialler; High Or
Low Fluid Level Detector (uses LM1830N);
Simple DTMF Encoder (uses Texas TMC5089);
Studio Series 20-Band Stereo Equaliser, Pt.2 ;
Auto-Zero Module for Audio Amplifiers (Uses
LMC669); A Guide To Hard Disc Drives.
October 1989: Introducing Remote Control;
FM Radio Intercom For Motorbikes (Uses
BA1_404 And TDA7000) Pt.1; GaAsFet Preamplifier For Amateur TV ; 1Mb Printer Buffer; 2- ,
Chip Portable AM Stereo Radio, Pt.2 ; Installing A Hard Disc In The PC ; A Look At Australian Monorails.
November 1989: Radfax Decoder For Your
PC (Displays Fax, RTTY and Morse); Super
Sensitive FM Bug ; Build A Low Cost Analog
Multimeter; FM Radio Intercom For Motorbikes,
Pt.2 ; 2-Chip Portable AM Stereo Radio, Pt.3;
Floppy Disc Drive Formats & Options; The
Pilbara Iron Ore Railways.
December 1989: Digital Voice Board (Records Up To Four Separate Messages, Uses
Texas TMS3477NL and 256K RAMs) ; UHF
Remote Switch ; Balanced Input & Output
Stages ; National Semiconductor LM831 Low
Voltage Amplifier IC Data; Install A Clock Card
In Your PC ; Index to Volume 2 (JanuaryDecember 1989).
January 1990: Service Tips For Your VCR;
Speeding Up Your PC ; Phone Patch For Radio Amateurs; High Quality Sine/Square Oscillator; Active Antenna Kit; The Latest On High
Definition TV; Speed Controller For Ceiling
Fans; Designing UHF Transmitter Stages.
February 1990: 16-Channel Mixing Desk; High
Quality Audio Oscillator, Pt.2 ; The Incredible
Hot Canaries; Random Wire Antenna Tuner
For 6 Metres; Phone Patch For Radio Amateurs, Pt.2; PC Program Calculates Great Circle
Bearings.
October 1990: Low-Cost Siren For Burglar
Alarms; Dimming Controls For The Discolight;
Surfsound Simulator; DC Offset For DMMs;
The Dangers of Polychlorinated Biphenyls; The
Bose Lifestyle Music System ; Using The NE602
In Home-Brew Converter Circuits.
November 1990: Low-Cost Model Train Controller; Battery Powered Laser Pointer; A
Really Snazzy Egg Timer ; 1.5V To 9V DC
Converter; How To Connect Two TV Sets To
One VCR ; Introduction To Digital Electronics;
Simple 6-Metre Amateur Transmitter.
December 1990 : DC-DC Converter For Car
Amplifiers ; The Big Escape ; Wiper Pulser For
Rear Windows; Versatile 4-Digit Combination
Lock; 5W Power Amplifier For The 6-Metre
Amateur Transmitter; The Green CD Pen
Controversy.
March 1990: 6/12V Charger For Sealed LeadAcid Batteries ; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes ;
16-Channel Mi xing Desk, Pt.2 ; Using The
UC3906 SLA Battery Charger IC; Digital Waveform Generation Using a PC ; The Controls On
A Model Aircraft.
January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine ;
Two-Tone Alarm Module ; Laser Power Supply
(For Tubes With Ratings Up To 10mW) ; LCD
Readout For The Capacitance Meter; How
Quartz Crystals Work; The Dangers When
Servicing Microwave Ovens; Electric Vehicles
- The State Of The Art.
April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio ; Relative Field
Strength Meter; 16-Channel Mixing Desk, Pt.3 ;
Simple Service Tips For Your Microwave Oven;
Maciel Aircraft Aerodynamics ; Active CW Filter
For Weak Signal Reception.
February 1991 : Synthesised Stereo AM Tuner,
Pt. 1; Three Inverters For Fluorescent Lights ;
Low-Cost Sinewave Oscillator; Fast Charger
For Nicad Batteries, Pt.2 ; How To Design
Amplifier Output Stages; Tasmania's Hydroelectric Power System .
May 1990: Build A 4-Digit Capacitance Meter ;
High Energy Ignition For Cars With Reluctor
Distributors ; The Mazzie CW Transceiver;
Waveform Generation Using A PC, Pt.3 ; 16Channel Mixing Desk, Pt.4; What To Do When
Your Computer Goes Bung , Pt. 1; Electronic
Load For Checking Power Supplies.
March 1991 : Remote Controller For Garage
Doors, Pt.1; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose
1/0 Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV ; A
Look At Config.Sys & Ansi.Sys ; High-Voltage
DC Transmission Systems.
June 1990: Multi-Sector Home Burglar Alarm ;
Low-Noise Universal Stereo Preamplifier; Load
Protection Switch For Power Supplies; A Speed
Alarm For Your Car; Design Factors For Model
Aircraft; Fitting A Fax Card To Your Computer;
What To Do When Your Computer Goes Bung,
Pt.2.
July 1990: Digital Sine/Square Generator, Pt.1
(Covers 0-500kHz); Burglar Alarm Keypad &
Combination Lock; Simple Electronic Die; Low-
PLEASE NOTE:
All issues from November 1987 to April 1988,
plus June 1988, are now sold out. All subsequent issues are presently in stock. For readers wanting articles from issues out of print, we
can supply photostat copies (or tearsheets) at
$5.00 per article, including postage. When
supplying photostat articles or back copies, we
automatically supply any relevant Notes & Errata , at no extra charge.
APRIL 1991
91
ASK SILICON CHIP
Got a technical problem? Can't understand a piece of jargon or some technical principle? Drop us a line
and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097.
High energy ignition
works well
I have recently bought and assembled successfully a High Energy
Ignition Kit from Jaycar Electronics,
as described in the May 1988 issue of
SILICON CHIP. I am pleased to say that
it works very well and have had no
trouble with it since installing it into
my 1979 929L Mazda. In your June
1988 issue, you described a method
of converting a car's distributor to Hall
Effect using either the Sparkrite kit or
the Bosch Vane/Siemens sensor combination.
I would very much like to convert
my car to Breakerless Ignition using
the Sparkrite kit, as no metalwork or
extensive fiddling is required. I have
only one problem and that is I cannot
find anyone who sells this kit in Brisbane. Jaycar no longer stock this kit
and no auto electrical stores I have
been to have heard of it.
I would really appreciate it if you
or any of your readers could supply
me with some information on a place
in Brisbane or Australia that still
stocks this kit. (T. G., Seven Hills,
Qld).
• As far as we know, the Sparkrite
breakerless conversion kit is no longer
manufactured. You are quite right
Unwanted amplifier
switch-off thump
Your "Ask SILICON CHIP" column has induced me to write to
you about a continual problem that
I have had over the years. I am
prepared to offer a $50.00 fee for a
simple, uncomplicated to build,
system to cure the problem below.
I have tried the power supply
kit described in the December 1979
issue of ETI in order to stop the
noise when an amplifier switches
on and off. The ETI kit works very
well at switch on, but not all the
92
SILICON CHIP
though, it is an ideal method of conversion.
You could consider obtaining a
distributor from a later model from a
wrecker's yard, which would make
the conversion a snack.
Failing that , you will have to look
around for a Hall Effect conversion
kit for your car. We understand that
the American companies Lumenition
and Allison do make a wide range of
Hall Effect conversion kits and a fair
number of Japanese cars are covered.
The best place to find out more about
these would be your local speed shop
- don't bother with ordinary auto accessory shops as they probably won't
know what you are talking about.
Alternatively, contact Lynx Engineering Pty Ltd in Croydon (phone
(02) 747 2222) for info on Allison
products.
Leak amplifier has
leaky capacitors
I have a Leak amplifier 50+50
which I would like to put to use, but
most if not all, the electros are shot. It
would probably be advisable to
change them all. As these are rated at
250 volts at least, my problem is a
source of supply.
Might it also be possible that Garry
time at switch off.
Basically, I would like a system
that does not connect the speakers
for a few seconds after power is
switched on and also holds the
240V AC power going into the
amplifiers for a few seconds after
the speakers have been switched
off. I hope that you can help me.
(G. D., Nambucca Heads , NSW).
• We presently have a muting circuit under development which
should suit your purpose. We hope
to publish it in the coming June or
July issue. We won't charge $50
for it, either.
Cratt could run a series of introductory articles on satellites from the
amateur point of view. Dependent on
the interest shown, it could be either
elaborated on, or dropped. (H. F. ,
Cloverdale, WA).
• High voltage electros are available
from two sources that we know of in
Australia. One of these is Farnell 's
and the other is RS Components. The
addresses are as listed below:
(1) RS Components: 3 Walters Drive,
Osborne Park, WA 6017 (PO Box 502,
Subiaco, WA 6008). Telephone (09)
244 3666.
(2) Farnell Electronic Components: 72
Ferndell Street, Chester Hill, NSW
2162. Telephone (02) 645 8888 .
A series of articles on satellite reception is in preparation and will be
published in a few months' time.
Inductance meter
is interesting
I read with great interest Victor
Erdstein's article on his inductance
meter design (See "Circuit Notebook",
page 20, February 1991). The design
is exactly what I have been looking
for. Will you be producing this at a
later date as a kit?
I was thrilled to see the AM tuner
project, also in the February 1991 issue. Is there an FM tuner on the way?
(B. C., Grange, SA) .
• Thanks for your comment on the
inductance meter. We do not have
any plans to produce this as a kit at
this stage but if sufficient readers
express an interest, we will consider
publishing it as a full project.
We do not have plans for an FM
tuner to match the AM tuner. Commercially available FM tuners are just
too cheap to make an FM tuner project viable.
Low tech blinkin' lights
are cheaper
I hope you will be able to help me
with this problem. I've had these
Christmas tree lights for a few years
now and like them because they have
a double blinker, or they did have
two until one failed. Unfortunately,
the blinker bulb is no longer available
to replace the one that is not working.
You may have seen these sets of
blinking lights. One cycle is a fraction longer than the other and so
makes it ever so nice to look at. It has
34 coloured lights, plus two of these
special ones which cut and connect
the circuit. Please let me know what
you call these and how they work?
Also, could you come up with some
kind of relay or a circuit to replace
this special bulb. (J. N., Mt.Warrigal,
NSW).
• The special bulbs which cause your
Christmas lights to blink have an internal bimetallic strip which makes
and breaks the electrical circuit. Your
set of Christmas lights apparently has
two separate series strings of 12VAC
bulbs, with each series string controlled by its own flasher bulb.
You can buy these bulbs from Tandy
Electronics (Cat. 2 72-1097) but there
is one problem. They are supplied
with flying leads rather than the
Edison screw base. You would have
to remove the existing flasher bulb
socket and wire the new bulb in its
place, making sure that the connections are very well taped up for safety.
Unfortunately, an electronic solution to replacing the flasher bulb is
not simple. Firstly, two flasher circuits would be required, with separate wiring to each circuit. Secondly,
the cost of all the parts for the flasher
circuit, including a case, would far
exceed the cost of buying a new lighting setup.
Questions on
digital circuitry
I have a number of questions for
you to answer. For a start, I was given
a 4003 by a friend but neither of us
know what it does or its pinouts.
Could you supply these? I would also
like to know the frequency limit of
the 74HC series ICs.
One last question: would you know
where I can obtain a 6-8 digit counter
IC with multiplexed outputs (of
course) with as high a frequency rating as possible, as well as data on it? I
will be using it to drive an 8-digit
vacuum-fluorescent display, so I can't
simply cascade a couple of 74C926s,
or higher frequency versions of these.
Help for
sick a Jaguar
I write to reply to J. E., Melbourne, regarding his problem
with' Jaguar electronic ignition (see
SILICON CHIP, February 1991, page
100 - "Sick Jag Needs Better
Spark"). Without furth er information, I am not sure which system
will be on his Jaguar but it is most
likely to be the Lucas transistor
assisted system using the Lucas
BA12 coil. (Yes, they are around
the $200.00 mark) .
Firstly, a good mechanic with
an ignition scope should be able
to tell J.E. whether the trouble is,
in fact , ignition or something else.
Secondly, if the problem is ignition-related, then there are a number of options :
(1) If the coil proves to be the
I read in a recent issue of SILICON
CHIP a reader's letter asking about a
digital ohmmeter proj ect. Why not
simply modify the Digital Capacitance
Meter project (May 1990)? All that
would be needed is a close tolerance
capacitor and a switch to toggle between resistance and capacitance
modes, as well as a close tolerance
resistor for calibration.
Now I would like to suggest a series of articles describing the design
of high quality amplifiers , explaining
all (or most) of the parameters involved in amplifier design and how
to overcome certain problems and
difficulties.
I think that such a series would be
greatly w elcomed by readers as decent amplifiers are not easy to design
properly. (D. M., Christchurch, NZ).
• We do not know what a 4003 IC is.
All the data books we have of the
4000 series CMOS ICs do not list a
4003 . Nor do they list 4004 or 4005
devices. It appears that these are obsolete devices or were never rel eased
for general us e.
The frequency limit of a 74HC
clocked IC is typically 50MHz and
the propagation delay for a gate is
8ns. For more detailed information,
w e suggest you obtain a High Speed
CMOS data book.
For a 6-8 digit counter, you can use
a 74C912 6-digit display controller
problem, and it is a Lucas BA12,
then it can be substituted by a readily available, much cheaper coil.
(I can supply details).
(2) The whole system can be
converted back to a points type
distributor and the High Energy
Ignition published in the May 1988
issue of SILICON CHIP used.
(3) Depending on which Jag distributor it is, it should be possible
to run the HEI from the reluctor
pickup.
(4) Again depending on the distributor, an aftermarket, optoelectronic or Hall Effect pickup can be
substituted and also run into the
HEI.
If J.E. wishes to write or phone,
I would be only too happy to help
further. (I. L., PO Box 557 , Bowral,
NSW 2576. Phone (048) 71 3162
(AH).
plus separate 4-digit counters using
the 74HC.
Your idea to convert the Capacitance Meter from May 1990 into a
digital ohmmeter is a good one - we'll
have a look at publishing the modifications soon.
Our February 1991 issue features
the first part of a two-part article on
amplifier design , which you should
find interesting. The second part is
published in this issue.
Model aircraft
projects wanted
Thanks for a well presented magazine. My interest in electronics and
model aircraft have been well catered
for recently by your informative articles on remote control by Bob Young
and projects for rapid chargers for
nicad batteries (I use it for electric
flight).
A further project to complement
these would be an electronic speed
controller, suitable for model aircraft/
cars. Desirable features would include: a variety of current capacities
(eg, 20 & 30 amps); the ability to operate from 4.8V receiver battery packs,
with suitable isolation such as optoisolators ; and compact, lightweight
construction. (M. R., Ringwood, Vic).
• Thanks for your suggestions - we'll
give them close consideration.
SC
APRIL 1991
93
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/
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Cash in your surplus gear. Advertise it here in Silicon Chip.
FOR SALE
WEATHER FAX programs for IBM XT/
ATs *** "RADFAX2" is a high resolution,
shortwave weather fax, Morse & RTTY
receiving program. Needs CGA, SSB
l::IF radio & Radfax decoder. Also
"RF2HERC", "RF2EGA" & "RF2VGA",
same as RADFAX2 but suitable for
Hercules, EGA & VGA cards respectively. $35. *** "SATFAX" is a NOAA,
Meteor & GMS weather satellite picture receiving program. Uses EGA &
r-------------------------,
VGA modes, needs EGA or VGA col our monitor & card, plus "WEATHER
FAX" PC card. $45. *** All programs
are on 5.25-inch or 3.5-inch discs (state
which) & include documentation. Add
$3 postage. ONLY from M. Delahunty,
42 Villiers St, New Farm, 4005 Old.
Phone (07) 358 2785.
LAB LASERS. 0.5mW to 2mW HeNe
lasers complete. Ideal for students or
hobbyists. Australian made. $440 to
$640. Phone M.C.E. Lasers (03) 357
0055.
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(02) 979 6503.
THE WORLD'S FIRST MS-DOS
pocket PC at Australia's lowest price.
Atari Portfolio $480 inc tax. Post & insurance free for mail orders. All accessories available at reduced prices. Uses
an 80C88 CPU & is video cassette
size. Data transfer to XT/AT via optional serial or parallel interface. For
more information, send a 43c stamp to:
Don McKenzie, 29 Ellesmere Crescent,
Tullamarine 3043.
DIGITAL WAVEFORMS from a PC. As
described in SILICON CHIP in March
1990, May 1990 & June 1990. The
software can also be used for the similar project (Simple PC Function Generator) described in Electronics Australia in January 1989. Software & PC
Board: $39.95 incl. p&p. Software only:
$32.50 incl. p&p. Money order or
IIT MATHS
COPROCESSORS
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2C-08
2C-10
2C-12
2C-20
2C87- 8MHZ
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2C87-20MHZ
/:"
°'1&1:
~~
,r:-0
'.-9 (
$330
$359
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$490
~&&
3C-16 3.C87-16MHZ
$640
3C-20 3C87-20MHZ
$680
3C-25 3C87-25MHZ
$840
3C-33 3C87-33MHZ
$990
These pices include Sales Tax. Stocks
are limited at this price, so order early.
CAD CONNECTION
PHONE (02)957 6719
CONNECTION
FAX (02)954 5550
Improving Your Produdirity
APRIL 1991
95
r
MEMORY EXPANSION
SIMM&SIP
sons
CO-PROCESSORS
21.00
73.00
375.00
68.00
9 x256
9x1MB
9x4MB
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DRAM/DIP
58.00
2.10
2.50
2.15
7.60
7.60
PELHAM
80287-10
TOSHIBA LAPTOP
INTEL
175.00
285.00
295.00
582.00
510.00
640.00
13200
T1600
T3100E
T3100SX
T1000SE
A. M. D.
SAVE 50% ON
CO-PROCESSORS
BOns
4MB Static
41256
41464
4164
1MB
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INTEL8087·1
INTEL 287XL
ITT 3C87SX16
ITT 3C87 -33
CYRIX 387DX20
CYRIX 387DX25
Price• At February 24th
168.00
3MB
2MB
2MB
2MB
2MB
4:10.00
270.00
270.00
270.00
480.00
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Sales Tax 20%. Overnight Delivery. Credit Cards Welcome
1st Floor, 100 Yarrara Road, Pennant Hills, N.S.W. 2120
Tel(02)980-6988
Arista .. ..... ...... ...... ... ... .... . 33,39,57
Cad Connection .... .................. .. 95
David Reid Electronics ........ IFC ,1
IBM PS/2
1MB
2MB
2MB
Altronics ...... .............. ..... ... .. .. 60-63
Back Issues .. .. ...... ..... ... ... .. ... 90,91
COMPAQ
386-20, 386-25, 386-20E, 386-S, 386-33
4MB MODULES
490.00
4MB BOArds
580.00
30/286,50
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70A21
Advertising Index
Fax(02)980-6991
\..
Dick Smith Electronics ... ....... 13-15
Electronic Solutions ..... .... ......... 35
Electronic Toy Services ............ 96
Electronics World ...................... 75
Elmeasco ....... .. .... ........ ... ... ..... IBC
Geoff Wood Electronics ... ........ . 29
Harbuch Electronics ...... .. ........ 57
MODEL TRAIN CONTROLLER project, SILICON CHIP, November 1990,
$19.95 plus $2.50 p&p. Plugpack,
12VAC, 1.7A, suitable for the above
(use rectifier), $29.95 plus $4.00 p&p.
Kits built & repaired. Prototype production board supplier to the hobbyist
& supplier of SILICON CHIP project
PCBs.
ETS, PO BOX 491,
NOARLUNGA CENTRE, SA 5168.
Phone: (08) 382 8919
MAX 1/0 Board
Kit $149.00 Built & Tested $269.00
• 7 x Relays SPST 2 amps each
• 8 x Switch inputs (TTL)
• 1 x DAG (Digital to Analog converter)
• 1 x ADC ( Analog to Digital converter)
• 4 x Motor Drive outputs (40mA ea.)
• 1 x Programmable timer output.
MAX includes a 20-page manual with all schematics, parts layout etc. , a 360K PC-compatible floppy
with diagnostic and sample software in GW-Basic.
MAX runs from a PC compatible printer port tor full
compatibility with a large range of computers.
Same day dispatch of orders . Credit cards or personal cheques welcome.
Phone (08) 332 6513 or Fax (08) 364 0902 (24 hours)
PC Computers, 36 Regent St, Kensington, SA
cheque . M. Radvanyi, PO Box 49,
Kingswood, NSW 2749.
CIRCUIT DESIGN SOFTWARE. Design your own .008% THD Sinewave
Generator from 90Hz-30kHz using the
PCB in SILICON CHIP, February 1991.
No PCB track mods required. $20 inc.
p&p.
Design & build you own Audio Power
Amplifier up to 20W. On-screen circuit
diagram and hardcopy facilities. Instructions included. $30 inc. p&p.
Custom-make your own SLA Battery
Charger using the UC3906 IC (4-30V).
Designed by the author of the SILICON
96
SILICON CHIP
FIX-A-KIT
$20.00 PER HOUR LABOUR
3 MONTHS WARRANTY ON REPAIRS
12 MONTHS WARRANTY ON CONSTRUCTION
Service to most types of electronic equipment
TECHNICAL ASSISTANCE
HVCAL ELECTRONICS
Design, Manufacture & Repair of Electronic
Equipment
Trading Hours Sam to 3pm, Monday to Friday
(02) 633 5897
Hycal Instruments .................... 96
Jaycar Electronics ................ 45-52
J.V. Tuners ........... ..... ................ 43
M. Radvanyi ...... ...... .. ... .... ......... 95
PC Computers .... .. ... ... .. ............ 96
PC Marketplace ......... ... ..... .. ..... 77
Pelham .................. ..... ..... ........ 96
Raytec Data Systems .. ............ 43
CHIP March 1990 project. $20 each
inc. p&p.
Buy all three for $50 and save $20! All
software IBM/XT/AT compatible, 5.25inch 360K disc only, CGA/EGA/VGA,
MS-DOS 3.2 or later, GWBASIC
required . 14-day turnaround . Send
cheque/money order to: D. Yates, PO
Box 134, French's Forest, NSW 2086 .
ANTIQUE RADIO
ANTIQUE RADIO restorations. Your
one-stop electronic repair shop. Specialising in restoring vintage radios including chassis rewiring, quality new
parts, valves , valve sockets, speakers,
transformers, cabinet restoration. Quality secondhand radio dials & parts for
most brands & models. About 400 radios in stock for restoration & parts.
Every restored wireless is covered by a
2-year warranty on parts & service.
French polishing of timber cabinets
available. Vintage car radios in valve &
transistor types available for restoration. Repairs done on tape decks,
amplifiers, TVs & videos . Open Sat.
10am-5pm; Sun. 12.30-5pm. 109 Cann
St, Bass Hill, NSW 2197. Phone (02)
645 3173 BH or (02) 726 1613 AH .
RCS Radio................................ 44
Resurrection Radio ... .. .. .. .. ... .... 39
Rod Irving Electronics .... .... .. 20,21
68,69,84,85
Sheridan Electronics ................ 83
Silicon Chip Binders .... ... ... .. OBC
Soundring ......... .. .. ........ .. .. ... ... . 33
Subscriptions ... .. .... ................... 94
PC Boards
Printed circuit boards for SILICON
CHIP projects are made by:
• Electronic Toy Services, 2/111
Glynville Drive, Hackham West, SA
5163. Phone(08)3828919.
• Jemal Products, 5 Forge St,
Welshpool, WA 6106. Phone (09)
350 5555.
• Marday Services, PO Box 19-189,
Avondale, Auckland, NZ. Phone 88
5730.
• RCS Radio Pty Ltd, 651 Forest
Rd, Bexley, NSW 2207. Phone (02)
587 3491.
Data I/ 0 2900 Programming System
the new standard in affordable device
DATA I/O
programming
Corporation
F eatures
• Universal pin driver technology eliminates
pinout adaptors and gives long term
flexibility in device support.
• Standard 40 pin DIP socket
• Optional Matchbooks\™ provide
quick, easy handling of
LCC and PLCC surface
mount devices.
from
$7586
(ex tax)
•
•
•
•
•
•
128kByte standard
RAM is expandable
to 2MB to accommodate
future devices.
Flexible interfacing allows 2900 to easily fit any
engineering environment. Control from existing
terminals or from a PC.
High speed 1/0 offers fast uploading and
downloading of large data files - up to l 15kbaud between the 2900 and a PC. Up to ten times faster
than conventional RS232.
For RS232 communications, SmartPort1 M
automatically senses protocol of the host and sets
up the 2900 to match. No cables to rewire, no
switches to set.
Job files and macros make setups automatic for
frequently used routines
Autobaud™ automatically senses the baud rate of
the host and sets up the 2900 accordingly.
•
Device Libraries
Device Type
Memory
Floppy disks provide fast
and easy device-support
updates and local
storage of
frequently
used files.
Memory
Librarv
E/EEPROM 28
(standard on all
2900 systems)
E/EEPROM All
Memory
PROM All
Microcontrollers
Logic
Logic
Logic
E-micros All
PLO 24
PLO 28
PLO 44
Devices Included
All EPROMs and
EEPROMs up to
28pins
All EPROMs and
EEPROMs
All bipolar and
CMOS PROMs
All microcontrollers
with on-board EPROMs
All PLDs up to 24 pin
All PLDs up to 28 pin
All PLDs up to 44 pin
ELMEASCO Instruments Ply.Ltd.
Australia 's Leading Test & Measuring Instrument Company
NEW SOUTH WALES
18 Hilly Street,
MORTLAKE
P.O.Box 30, CONCORD
NSW 2137
Tel : (02) 736 2888
Telex : AA25887
Fax : (02) 736 3005
VICTORIA
12 Maroondah Highway,
RINGWOOD
P.O.Box 623 , RINGWOOD
VIC 3134
Tel : (03) 879 2322
Telex : AA30418
Fax: (03) 879 4310
QUEENSLAND
192 Evans Road ,
SALISBURY
P.O.Box 274 SALISBURY
OLD 4107
Tel : (07) 875 1444
Fax: (07) 277 3753
SOUTH AUSTRALIA
241 Churchill Road,
PROSPECT
P.O.Box 154 PROSPECT
SA 5082
Tel : (08) 344 9000
Telex: AA87519
Fax: (08) 269 6411
W. AUSTRALIA
32 Teddington Road,
VICTORIA PARK,
W.A. 6100
Tel: (09) 470 1855
Fax: (09) 470 3173
|