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This is only a preview of the May 1992 issue of Silicon Chip. You can view 47 of the 96 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Articles in this series:
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A LOOK AT LARGE SCREEN MONITORS
AUSTRALIA'S DYNAMIC
- ELECTRONICS MAGAZINE~
- - -~
- D I PTRONICS-
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=~~,!f~!~E,,
0 f\ Bayswa er., 1.5.
P.O. Box 664, Bayswater 3.153
Telephone: (03) 761 4466 \
Facsimile: (03) 761 4161
Toll Free: (008) 800 482
~
~ ~ m~ Road,
1::11~
namsgate
Sans Souci 2219
Telephone: (02) 529
Facsimile: (02) 529
,""
. ----------.-------\ a,,,
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227,7
589\
• Capac.itors • Connectors • Fans • Filters • Headers • LEDs • Plugs • Rectifiers • Relays
Resistors • SCRs • Triacs • Sockets • Swtiches • Terminal Blocks • Varistors
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--Vol.5, No.5. May 1992
••
_,
•
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FEATURES
,
,,.
,
("
..
o.'
•
•
•
6 We Take A Look At CD ROM by Darren Yates
FORGET ABOUT CAD & desktop
publishing on a small screen. A
high-resolution, large-screen
monitor is really the way to go.
We tell you what to look for in
our story starting on page 16.
A large range of software is now available
16 Computing On The Big Screen by Jim Sharples
A look at large-screen, high-resolution monitors
_ _ _ PROJECTS TO BUILD __ _
__
30 A Low-Cost Electronic Doorbell by Darren Yates
Build it from junkbox parts
36 The Eliminator by Marque Crozman
It runs your personal player from a 12V DC supply
58 Build A Telephone Intercom by Greig Sheridan
Works jusdike a real telephone system
76 lnfrared Remote Control For Model Railroads, Pt.2 by John Clarke
Remote control receiver circuit & pulse power board construction
-
SPECIAL COLUMNS
•
f
•
• •
•
...
DO YOU HAVE A COUPLE of
old telephones sitting in your
junkbox.? This project will turn
them into a useful intercom unit
that works just like a real
telephone - see page 58.
•
24 Computer Bits by Paul Lynch
The PC game is changing again - OS/2 is really here
40 Serviceman's Log by the TV Serviceman
Five faults all at once!
THE SERVICEMAN suffered a
frightening encounter with a
Panasonic TV set this month. His
tribulations begin on page 40.
68 Vintage Radio by John Hill
The basics of receiver alignment, Pt.2
86 Amateur Radio by Garry Cratt
· Receiving weather satellite signals, Pt.2
~
.
-
.
"'
DEPARTMENTS. . .
2 Publisher's Letter
4 Mailbag
22 Circuit Notebook
53 Product Showcase
88 Back Issues
..
Ask Silicon Chip
Notes & Errata
Order Form
Market Centre
96 Advertising Index
90
92
93
94
. .
...
DON'T BUY A
new doorbell to
replace your
bro,ken-down
unit. This design
comes in a
special case &
uses readily
available parts
to produce a realistic & pleasant
"ding-dong" sound. Construction
begins on page 30.
MAY 1992
1
Publisher & Editor-in-Chief
Leo Simpson, B.Bus.
Editor
Greg Swain, B.Sc.(Hons.)
PUBLISHER'S LETTER
Technical Staff
John Clarke, B.E.(Elec.)
Robert Flynn
Darren Yates
Reader Services
Ann Jenkinson
Sharon Macdonald
Sales & Marketing Mgr.
Sharon Lightner
Phone (02) 979 5644
Mobile phone (018) 28 5532
Regular Contributors
Brendan Akhurst
Jennifer Bonnitcha, B.A.
Garry Crall, VK2YBX
Marque Crozman
John Hill
Jim Lawler, MTETIA
Bryan Maher, M.E., B.Sc.
Jim Yalden, VK2YGY
Bob Young
Photography
Stuart Bryce
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
Ply Ltd. A.C.N. 003 205 490. All
material copyright©. No part of this
publication may be reproduced without the written consent of the publisher.
Printing: Magazine Printers Pty Ltd,
Alexandria, NSW; Macquarie Print,
Dubbo, NSW.
Distribution: Network Distribution
Company.
Subscription rates: $42 per year
in Australia. For overseas rates, see
the subscription page in this issue.
Liability: Devices or circuits described in SILICON CHIP may be
covered by p21tents. SILICON CHIP
disclaims any liability for the infringement of such patents by the manufacturing or selling of any such
equipment.
Editorial & advertising offices:
Unit 1a/77-79 Bassett Street, Mona
Vale, NSW 2103. Postal address:
PO Box 139, Collaroy Beach, NSW
2097. Phone (02) 979 5644. Fax
(02) 979 6503.
ISSN 1030-2662
2
SILICON CHIP
PC technology is moving rapidly ahead
This month, we are taking a look at three areas of PC technology that are
evolving rapidly. The first of these is our feature article on large screen video
monitors. These are not new of course and specialised labs employing CAD
programs have had them for quite a few years. What is new is that they are
now becoming much more affordable although most private users would
still baulk at paying between $3000 and $5000 for a high resolution colour
monitor and accompanying video card. Still, the prices were very much
higher as little as two years ago and as computer prices have dropped so
much, you can now buy a high end system with a big monitor for the same
price that you would have paid a few years ago for a less capable system with
a 14-inch screen.
We also take a look at one of the latest CD ROM packages. When CD ROM
came out a few years ago it was stymied by a severe lack of software and the
hardware wasn't cheap either. That has changed rapidly and there is now a
wealth of interesting software on CD ROM. We can see many families adding
a CD ROM to their home computer and thereby gaining a very good
reference base for school assignments.
And finally, we take a look at OS/2 version 2. IBM's much vaunted 32-bit
replacement for DOS has languished badly since it was originally released
in 1987 but now it looks set to really compete with Windows-based
software, with the advantage that it should operate much faster. It will be
very interesting to see how much OS/2 based software appears over the next
few years - the PC will evidently continue to change extremely rapidly over
the coming years.
These rapid changes do present their problems though. For people
considering buying a home computer so their children will not be left
behind, there is a particular dilemma. Whatever computer they buy now, it
is not likely to bear much similarity to the ones that will be used when their
children enter the workforce in five or more years time. And for business
users, the problem is that no matter what system they buy, its value will
rapidly diminish in the space of two years or so. So if they are making
buying decisions now, the computers must pay for themselves several times
over in two years or less.
The other side of the coin is that if businesses do not continually update
their equipment, and that includes their computers, then they will be
rapidly left behind in the marketplace.
Leo Simpson
Ars your eugfo111srg /Javi11g trou/Jls gstti11g t/Jroug/J to your p/Jo11s/rax li11s ?
illl'i~I
a11d you'vs loGt t/Js Gals /lseauGs your fax Gwite/J iG 11ot doi11g w/Jat you wa11t it t o do?
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Why the EASY-CONNECT ?
The VSI EASY-CONNECT
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sha ring device av ailable in Australia today.
Integr ate an y fax with any answering
machine on an y telephone system without
th e limitations of faxswitch devices or
3 in 1 fa x s yst ems.
The Most Advanced PHONE-FAX/LINE SHARING DEVICE
NO Confusing Vo ice Messages .
NO Perio d s o f Silence.
NO Unusual Dial Tones.
NO Delay s.
NO Frust rat ed Callers.
T he E A SY -CONNECT is totally trans pare nt.
Yo ur callers w ill never know it's o n the line !
* Sa ve installat ion and re ntal costs for a s epara te line.
** Latest
Sw itches incoming Fa x calls automatically on receipt of calling Fa x ton es.
VOICE PRIORITY technology.
* Installs in minute s on ANY PHONE SOCKE T usin1 supplie d connectors.
* DOES NOT REQUIRE EXPENSIVE TELECOM INSTAL ATION .
Other fa xswitch systems ?
Clum sy fa x priority operation .
Delay s, pause s. voice messages,
fru s trate d ca llers .
Inflex ible and limite d operation with
oth er device s.
Mus t be fitted on fir s t socket.
Poor history of cus tomer satisf action.
Dedicated fax line ?
$210 min . installa tion, $ 22 monthly
rental thereafter.
$472 min. in first year, over $1000
in 3 years. (1991 fees)
Installation delays.
Ch ange of premis es results in further
$ 210 installation fee .
Inefficient use of resources for small
businesses.
No available lines in some areas.
* Adds HOLD FACILITY to all phones. Puts a call on hold from any phon e.
* Manual Tr a nsfer to Fax before, dur ing or after voice conversation.
* Can interupt a voice conversation, to send or receive a Fax, then resume.
* Works with or without an Answering Machine. Pulse / Ton e dial compati a bl e.
* Will operat e with Fax, Phone, Modem and Answering Machine on one lin e .
* No restriction to the numbe r of extensions or other de v ices conn ec ted t o it.
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: ~~o~~~CJe?i:~\~ry i~g~e~ l~~l~!r~gae2
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Also work s with Command er, Keyphone or PABX (technic al installation req u'd)
The EASY-CONNECT is c ompatible with the changing ne eds.
Provides Lightning protection for the Fax and other devices connect ed to it.
Made in the U.S.A.
Telecom Australia Permit Number: A90 / 14B / 03 4 2.
Size: 8 5mm x 9 0mm x 33mm . Wgt: 225g.
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Requiremen ts: 115 / 240V AC 50/60H z.
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Range: 1Hz - 100MHz
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60MHz - 100MHz: 25mV.
■ Resolution: 0.1, 1, 10, 100Hz.
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■ Display: 8 digits LED.
Sine, Square, Triangle, Skewed Sine,
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■ Frequenc y: 0.02Hz - 2MHz.
■ Output: 0.1 Vpp - 20 Vpp.
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Internal: 20ms - 2s.
DC V, AC V, Ohm's, DC A, AC A .
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Ripple: • 2, • 3- 2mV max .
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■ 12 months Warranty.
Now available at an affordable price I
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Luminou s Intensity "' 20m A: 7mcd (min.). 14mcd (lyp.)
Forwa rd Voltage: 2.7V (min.l . 3.0V (t yp.), 3.5V (ma x.) o 20mA.
Reverse Voltage: 5.0V.
Full Viewin g Angle: 30 deg.
Wave Leng th: 470nm.
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5mm Part No.: L-53BC (BLUE)
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Electronics
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12 months warra n ty
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Pos t al Charges
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MAILBAG
Radiation limits for
low power transmitters
An article, published in the March
1992 issue of your magazine concerning a project for a low-power UHF
transmitter for use with VCRs, has
come to the Department's attention.
This equipment is subject to Equipment Compliance Requirement 315
(ECR 315) incorporating Ministerial
Standard 315 (MS 315) for Wireless
Video Equipment, copy enclosed.
If in the course of an investigation
of a complaint by the Department,
this device is found to be the cause,
then there could be some problems
for the owner of such equipment. If
further investigations show that the
equipment does not meet the requirements of MS 315, under the Radiocommunications Act 1983, it would become a sub-standard device. Possession of a sub-standard device is an
offence under the Act.
In order to assure compliance with
MS 315, it would be necessary to submit a device with an appropriate antenna to the Department for compliance testing. The fee for testing this
device is $420 plus $50 for a certificate. It would also be a requirement
for parts to be labelled correctly stating that the device complies with MS
315 and quoting the Departmental
approval number.
Although the exact power output is
not stated, the MS 315 requirement is
that the peak vision carrier field
strength shall not exceed 76dB microvolts per metre at three metres.
I commend your magazine for warning users of the potential to cause
interference to neighbours. However,
from the above it is evident that the
problem could become more serious.
Jim Little,
Radiocommunications Operations
Branch, Canberra, ACT.
Appreciation for
the TV Serviceman
Do excuse my addressing this note
to just "The TV Serviceman" but that
was the writer of your "Serviceman's
Log" column as listed in the index. I
4
SILICON CHIP
am rtot in the habit of writing fan
letters but I felt moved today, just as I
started to read my newly purchased
copy of SILICON CHIP, to drop a few
lines to express my appreciation of
your column.
Indeed, I find that it is the first part
of the magazine I turn to! Just can't
wait to get my feet up with a cold
drink at hand and read of your latest
antics and trials and tribulations.
I am an electronics engineer by profession, though it would be more accurate to say hard-core tinker in all
honesty. I have worked in a semiconductor factory, then serviced computers, and lately am moving into software. In all that time, and ever since I
was old enough to hold a screwdriver
come to think of it, I have had on
many occasions cursed gremlins,
damned elves and chased ghosts, convinced that science and technology
had nothing to do with any of their
handiwork. ICs that test fine but just
do not work in circuit, computers that
work perfectly the moment I so much
as look at them (but not at other times) ,
programs that adamantly believe 2 +
2 = 5, and even coils that sing an
elegant soprano ... I have had my share.
Reading in your articles of similar
plagues Down Under may have been
what has kept me sane (though I suspect there are folk around here, especially my long suffering wife, who
will claim otherwise). At the very
least, it has been therapeutic to know
I have not been singled out for the
undivided attention of you-knowwhat.
On a more serious note, I have benefited from the nuggets of wisdom
passed on, and have saved time, effort
and money due to hints and shortcuts in your column. And the cartoons really do illustrate your points
quite admirably. My compliments to
the artist!
A big thank you for the entertainment, consolation and information. I
look forward to reading your column
for a long, long time to come.
Y. W. Loke,
Petaling Jaya, Malaysia.
SILICON CHIP,
PO Box 139,
Collaroy Beach 2097.
Support for
microprocessor kit
Regarding the suggestion that you
develop a microprocessor development kit, I believe that you might be
surprised at the amount of interest. It
seems that there is a fair scattering of
people who want to get closer to the
technology than the use of a PC usually allows.
Some satisfy this urge by getting
something like a Commodore 64,
which is fairly powerful and yet simple enough for "hands on" experience and modification. On the other
hand, if one wants to start from ·the
ground up, there is almost nothing
better than a kit for getting acquainted
with the nitty-gritty. Provided the
price can be kept reasonable, it would
be attractive to keen students, and
find use as a programmable controller
for a wide range of devices.
There would be problems in choosing the chip-set for such a kit. Obviously, one type ofMPU would have to
be chosen and any choice would be
objectionable to some potential users
because of price and availability (of
support chips, too) and because the
order-code is not "as good" as one's
preference.
Then too there are onerous decisions to take, like the notion of an
RS232 (serial) interface, which would
(according to some) eat up valuable
board space better utilised for parallel input/output access.
It is perfectly feasible to build a
small system from scratch using perf
board and point-to point wiring. In
fact, this is the way I built a microcontroller for a wheelchair as a TAD
(Technical Aid to Disabled) project. It
used a 6800 MPU, 6810 RAM (128 x
8), 2716 EPR0M (2Kx 8), 6821 PIA and
a modicum of other components for
"logic glue" and analog signal handling.
Such an effort is somewhat harder
than just soldering bits into a readymade circuit board but the sense of
achievement is very rewarding.
E. Wormald,
Florey, ACT.
Function generator
Frequency Counter
Digital Multimeter
Power Supply
Ideal for the professional and keen
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the features -
Function Generator
• Sine, square. triangle. skewed
sine. pulse TTL level square
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• Output from 0.11/pp to 20Vpp
• Linear and Log sweep - 20ms to
2s (int) or 100:1 VCF (ext)
• 500/600'1 output
Miniscope
The pencil iron wrth real power.
Manual control of temperature while
• soldering. Surts light to medium
dutv work
e 10W to 70W ad1ustable
• Ad1ustable 200° to 500°C
• 5 seconds to reach 20'C
• Easy owner maintenance
• Low 4V supply
• Automatic SWIICh·off
Frequency Counter
e 1Hzto100MHz
e 15mV sensitivity to 60MHz
• 0.1 to 1OOHz resolution
• 10ms to 1Os gate
• 10MHz reference with 5ppm
stability
.
• 8 digrt display wrth annunciators
Dialtal Multimeter
e 31/2 digrtLCD
• Auto/Manual ranging
• Vdc, Vac.n. Ade, f>i.c functions
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e oata Hold
• Memory mode for relatiuve
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at $837 .DOinc tax
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80
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Power Off after 15min
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Weller
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SCOPE·SK2-0IB
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components.
• Grounded tip protects voltage
and current sensitive
components.
I Ih I
48w I · I
• const~i;i;~s see ea er
• Non-burning silicon rubber cord
• 15 tip sizes· 0.8mm to 6.00mm
• 11secs to recover for 37'C drop
• Choice of tip temperatures
315:cisoo:F, 370'C/70'Fi
430 C/800 F
155.00
•
•
•
•
•
•
No electricity
No batteries
Gas operated
Ready to use in 30 seconds
Refill _in moments . .
h
Hot air blower and mmi-torc
burner
..
• Up to 3 hours us_e from one filling
Weller Pyropen weighs only 90gm
and offers temperature co_ntr_ol from
200 lo 500' C • It has.a ~uilt,-m
1gn1tor and gas level md1cat1on..
Flame and temf;erature are eas1_ty
controlled bys idmg lever. Choice of
14 tip shapes plus 4 gas/hot a_ir
blowers. Can.be usecf for. brazing up
to 1300'G with special tip.
Supplied m metal storage box
containing tip wipper.
WELLER·PTAA61.6mm313d Sdriver
WELLER-PT AA7 1.6mm 370d Spade
WELLER-PTB7 2.4mm 370d Sdriver
WELLER·PTB8 2.4mm 370d Sdnver
WWEELLLLEERR··PTPTB B1 2._4 mmmm 3700dd Sppaaddee
43 5
888 2 4
WELLER·PTC6 3.2mm 315d Sdriver
WELLER-PTC7 3.2mm 370d Sdriver
WELLER·PTC8 3.2mm 430d Sdriver
WELLER-PTCC7 3.2mm 370d Spade
WELLER·PTF7 0.8mm 370d Con Rat
WELLER·PTH7 0.8mm 370d Sdriver
WELLER·PTH8 0.8mm 430d Sdriver
WELLER-PTK6 1.2mm 31 Sd LSdriver
WELLER·PTK7 1.2mm 370d LSdriver
WELLER·PTKB 1.2mm 430d LSdriver
WELLER·PTL7 2.0mm 370d LSdriver
WELLER·PTLB 2.0mm 430d LSdriver
WELLER-PTP6 o 8mm 31 Sd conical
WELLER·PTP7 o•smm 370d Conical
r65.90 WELLER·PTPB 0.8mm 430d Conical
SC5000A DI:• ~\~~
,, "'" •~·""
Desoldering
Tool.
225.40
55.60
41.95
63.55
14.20
~~
<('\
Now fitted with SOW heater. NEW
Hot air nozzle makes rt easier to
remove surtace mount devices.
Price 1s unchanged at $399 ex tax
78
Stand
($4
\
,,,
SMD Removal
i$-ii~6 Kit.
Comes wrth filter pipe, stainless
steel wire and blade rollshwire
Miss E.A. December?
holder, blade holder and at air
Then send for 8 page FREE nozzle. Surts SC5000A and SC-700
.
$82.80
Semiconductor Listing
Geoff Wood Electronics Pty Ltd
NEW SC-7000
DeSoldering Tool
• Now with 1OOW ceramic heater
• Work on up to 12 layer boards
• Special antistatic housing
e Optional surface mount krt
$482.50 ex tax
$579 inc tax
Solder 1.25, 0.9 and 0.71 mm
250gm
$7.95
500gm
$14.95
Solder Wick
$2.95
(Inc 1n N s W)
229 Burns Bay Road, (Corner Beatrice Street), Lane Cove West N SW
Mail Orders to - P O Box 671, Lane Cove N S W 2066
Telephone: (02) 428 4111 Fax: (02) 428 5198
8.30am to 5.00pm Monday to Friday. 8.00am to 12 noon Saturday
Mail Orders add $5.00 min to cover postal charges
Next day delivery in Sydney ~dd $8.00
All prices Include Sales tax unless stated otherwise
·
Tax exemption certificates accepted if the line value exceeds $10.00
BANKCARD, MASTERCARD, VISA, CHEQUES or CASH cheerfully accepted.
We take a look at Sony's new
D-R
If you thought that the CD ROM was just a clever
toy with no real place to go, then think again.
Now, more than ever, CD ROM brings a whole
new world of information as close as your PC.
By DARREN YATES
Remember back to those grand old
school days when you had to do those
natural science assignments and you
spent hours looking up books for information on all sorts of animals?
Often you found one photo and only
a couple of paragraphs of information
when you had to write four pages! If
you think about it, it's amazing how
things have changed in just the last 10
years, let alone the last 50!
The CD ROM makes it possible to
store 680 megabytes of information
on a single compact disc - or, in other
words, a complete edition of the Encyclopaedia Brittanica from A to Z.
But if that isn't your cup of tea,
then what about desktop publishing,
wildlife, history, music, engineering?
- the list of titles now available for CD
ROM is growing all the time in a wider
area of subjects.
So, when we were offered the
chance to review the latest Sony package from Pelham Pty Ltd, it was a case
of "who's first to play with it?" For
just $1140, you can purchase everything you need to get their CD ROM
up and running; from cables to the
software and the CD ROM card.
But of course, the whole package is
useless unless you've got software to
go with it. Fortunately, they've covered this end of the wicket as well by
providing a package containing six
discs, each in its own container.
The titles included are Compton's
Illustrated Encyclopaedia, National
Geographic Society's Mammals, Languages of the World, World Atlas and
CD Player Simulator software. This
selection is claimed to be valued at
over $3000.
The CD ROM drive itself is very
compact, measuring approximately
320 x 180 x 50mm, and it contains its
own power supply so that it doesn't
have to reply on the computer's supply. The front panel of the drive contains a thumbwheel volume control,
the CD eject button and a 3.5mm stereo
socket for a pair of
headphones. A dualcolour LED shows
when the CD is being
accessed by the computer; orange for access
and green for ready.
Sony have done their
best to make sure that
installing the CD ROM
is as easy as installing
any other peripheral
into your PC. They've
even given you the corBoth the software & the
hardware for Sony's
CD ROM are easy to
install. You can use it
with just about any
computer from an XT
up, although at least an
AT with a VGA
monitor & driver card
is recommended.
6
SILICON CHIP
rect Phillips-head screwdriver to undo
the computer case!
The CD ROM card is a half-width
unit that will fit into any expansion
socket on an XT through to a 486.
There are no DIP switches to set and
it's very easy to install.
The socket at the end of the card
simply connects to either one of the
sockets on the back of the CD ROM
drive. After that, it's just a case of
connecting up the power cable and
you're ready to go.
Installing the software
The driver software for the CD ROM
comes on a single 5¼-inch or 3½-inch
floppy disc. All you have to do is load
in the disc, type "llinstal" and press
return.
The installation software automatically loads in and then asks you what
sections of the 6-pack CD-ROM software you wish to load into your hard
disc. There's a very good reason for
this, too. The demo program, which is
a top-grade mix of high-resolution
graphics and digital stereo sound, is
about eight megabytes (8Mb) long and
when you add that to everything else,
the total comes to about 17Mb!
Once you have decided on what
software you want loaded in, the
driver software prompts you to load
in the correct CD and away it goes.
When it's completed, it also automatically reboots your computer so
that changes it has made to the
CONFIG.SYS and AUTOEXEC.BAT files
take effect.
If you had enough room on your
hard disc to load in the demo program, go to the LASERLIB directory
and type "lldemo" and press return
and you'll learn briefly how the CD
ROM system works.
Six-pack software
As mentioned before, there are six
CDs provided with numerous reference titles. To give you a taste of what
you can expect, we'll take a brief look
at a couple. To load in one of the CDs,
you have to load it into a plastic caddy
which then fits into the CD ROM drive.
When you consider that some CD
ROM drives now do without this
caddy system and no CD players have
it, you wonder why Sony has persisted with it. From our point of view,
it was about the only negative feature
of the whole package.
But that aside, you only need to
change discs when you change applications.
CD music sampler
Although not one of the bigger programs, this is one that is sure to be a
hit in just about every workplace (including here in our editorial offices)!
WHERE DO YOU GET IT?
o~
(<,~
The unit is supplied complete with six CDs, including Compton's Illustrated
Encyclopaedia, National Geographic Society's Mammals, Languages of the
World, World Atlas and CD Player Simulator software.
QLD'S LARGEST SUPPLIER OF MICROWAVE OVEN PARTS & ELECTRONIC COMPONENTS
REPLACEMENT
PARTS
DISTRIBUTORS
FOR
•
A
SHARP
Panasonic
AKAi
e TV
e CAR STEREO
e VCRs
e STEREO
e BUSINESS EQUIPMENT
e WHITEGOODS
e PHONES
e VIDEO CAMERAS
e MICROWAVE OVENS
A RANGE OF MAGNETRONS, DIODES, CAPACITORS & SHEET MICA TO SUIT
MANY MODELS & BRANDS OF MICROWAVE OVEN
lf
ffi
EDSON FIELD PTY LTD (A.C.N. 010 378 588). Trading as:
ECONOMIC ELECTRONICS,
24 Campbell Street, Bowen Hills, Old 4006.
PO Box 481, Fortitude Valley, 4006
Telephone (07) 252 3762.
SOUTHPORT ELECTRONIC SHOP,
Shop 1/ 10 Welch St, Southport, Old 4215. Telephone
(075) 32 3632
Fax (075) 51 0543
I
VlSA
I
e VAST RANGE OF COMPONENTS e TEST EQUIPMENT e TOOLS e SOLDERING EQUIPMENT
e DATA BOOKS e AUDIO/VIDEO ACCESSORIES e CABLE & CONNECTORS
MAY 1992
7
You can now
afford a satellite
TV system
For many years you have probably
looked at satellite TV systems and
thought "one day".
You can now purchase the following K-band system for only:
$995.00
These two off-screen shots are from
the National Geographic Society's
Mammals & from World Atlas.
Here's what you get:
*
A 1.8-metre prime focus dish
antenna, complete with all the
mounting hardware.
This program allows you to play your
favourite music CDs through your CD
ROM and even has a VGA screen display of one of Sony's CD players, complete with shuffle play, repeat and all
the standard CD player features.
But the best thing from a work point
of view is that the software is clever
enough to be able to play your CDs in
the background while you get on with
other work on the computer. That's
pretty clever stuff. And what's more,
the sound quality is just as good as
from any conventional CD player.
Sony even provide you with a pair
of stereo headphones that plug straight
into the front of the CD ROM for private listening while you work.
* One super low-noise LNB (1.4dB
or better).
*magnetic
One Ku-band feedhorn and a
signal polariser.
* 30 metres of low-loss coaxial
cable with a single pair control line.
* lnfrared remote control satellite
receiver with selectable IF & audio
bandwidth, polarity & digital readout.
Your receiver is pre-programmed
to the popular AUSSAT transponders via the internal EEPROM
memory. This unit is also suitable
for C-band applications.
Call, fax or write to:
AV-COMM PTY LTD
PO BOX 386, NORTHBRIDGE
NSW 2063.
Phone (02) 949 7417
Fax (02) 949 7095
All items are available separately.
Ask about our C-band LNBs, NTSCto-PAL converters, video time date
generators, FM 2 & EPAL & Pay TV
hardware.
I
I
II
----------Name ...... .. .... ... .. ... .. .. ............... ... ....
I
I
II
I Address ........... ... .. ........ ... ...... ...... ... .
I
I ........................... P/code .... .. ..... .....
II Phone .... ...... .. ..... ....... .... ...... ..... .......
I
I
I
II
YES GARRY, please send me more information on K-band satellite systems.
. ___________ .I
I
8
ACN 002 174 478
SILICON CHIP
01/92
CD player software, you'll hear a
myriad of animal sounds in both ears.
CD ROM catalog
National Geographic
Also included in the "6-pack" is a
CD ROM catalog which shows the
CDs currently available from Sony.
The list is truly diverse and includes,
among other things , an aircraft registration compendium, Battle Chess ,
CIA World Fact Book, Variety's Video
Directory, Shakespeare on Disc and
Coate's Art Review. They're priced at
between $80 and $500, depending on
the application.
One CD contains the complete 26volume edition of Compton's Family
Encyclopaedia with over 32,000 articles, 1500 illustrations and sound recordings. What's more, you don't have
The most spectacular package
comes from the National Geographic
Society. Called "Mammals " the program contains information on over
200 mammals, all complete with full
colour photographs.
But this is where the CD ROM leaves
books behind. Also included are
sound recordings and real life footage
from some of the National Geographic
films on a large number of mammals.
You can even get a printout of the
information provided on a particular
screen by clicking on the PRINT tile.
To be able to store so many audio
recordings of the mammals shown,
the right and left channels contain
different tracks. For example, when
you listen to what an old-world monkey sounds like, the sound is reproduced in the left ear. If you listen to,
say, a moose later, you may hear that
in the right ear.
If you play the Mammals CD via the
The CD is placed in a plastic caddy
before being inserted into the player.
to flip through reams of pages; instead, you just follow the pathways to
the particular subject of interest.
Again, the same method of storing
so many sound tracks has been used
here. If you play this disc through the
CD player software, you'll hear two
separate tracks in both right and left
ears. The program, of course, only
allows you to hear the sound recording of interest.
Play CD's On Your Computer
World Atlas
One way to help with geography
assignments is to have a good atlas
and this CD ROM system has one. It
gives you a picture of the world and
by using either the keyboard or a
mouse, you can select any region of
interest and it will display that almost instantly on screen. You can then
select any country from that particular region and look at it more closely.
Overall, the CD ROM system allows you to instantly access a whole
world of information previously only
available at large reference libraries.
As a teaching tool, it provides students and teachers alike with fast,
instant information on the latest topics from music, science, art, biology,
history and geography - the list goes
on.
With the way that CD ROM is expanding, it won't be long before you
can buy the software as easily as you
can buy music CDs.
The Sony CD ROM package from
Pelham is areal winner. At only $1140,
it represents terrific value for money,
particularly when you consider the
amount of information being made
available and the current cost of many
of the reference works provided.
Although many of the CDs available use high-resolution VGA graphics, many CDs also support CGA and
EGA standards as well and there are
plenty that don't even require graphics cards. So there are lots of good
reasons to consider a CD ROM for
your computer.
If that doesn 't interest you, think of
the complexity of the games that will
be possible - at the very least, you
should get digital stereo sound and
motion picture graphics.
The system reviewed here comes
complete with drive, CD ROM card,
installation software, the "six pack"
reference library, CD cassette tray,
cables, headphones, screwdriver and
user manuals. The system require-
THE LATEST
MULTIMEDIA SENSATION
..... CD-ROM
YOU GET ...
•3
-
• Textual Information
• CD quality audio sounds
• Photographic Images
• Motion Video
• SOUND BLASTER PRO
Short Version
SENSATIONAL CD TITLES
Creative's Sounds
Microsoft Windows 3.0
Microsoft Bookshelf,
includes Atlas,
Encyclopedia & more!
Cat X-2250
DISK STORAGE BOXES
5.25" Holds 50 disks Cat X-3531
5.25" Holds 100 disks Cat X-3534
Mini IBM Joystick Cat X-3581
For more information on your nearest store location
Phone: (02) 888 3200
PHONE ORDERS: SYDNEY AREA 888 2105 OUTSIDE SYDNEY (FREE CALL) 888 22 6610
81319
DICK SMITH (WHOLESALE) A.C.N. 000 908 716
ments are an XT or AT personal computer, 512Kb RAM minimum,' DOS
3.1 or higher, a hard disc, and a VGA
card and monitor (recommended).
For more information, contact
Pelham Pty Ltd on (02) 980 6988; or
see them at 1st Floor, 100 Yarrara Rd,
Pennant Hills, NSW 2120.
SC
MAY 1992
9
· 3 year warranty!
OPTIONAL EXTRAS
ADD PRICE TO BASE SYSTEM COST.
lM VGA CARD .. $150
512K VGA CARD .. $50
TO CHANGE A 85M HARD DRIVE TO A
126M HD add $175 105M HD .. $105
200m HD add $675 ISOM HD .. $575
(286-21
80286-16 CPU ._______...__
1 MEG RAM EXPANDABLE TO 4 MEG
21Mhz LANDMARK SPEED TEST
1.2M JAPANESE BRAND F.D.D
85M HARD DISK DRIVE 28ms ACCESS
101 EXTENDED "CLICK .. KEYBOARD
JAPANESE KEYBOARD SWITCHES
MINI CASE & 200W POWER SUPPLY
SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.20•• DP
2 SERIAL, PARALLEL, GAME PORTS
3 YEAR PARTS & LABOUR WARRANTY
256K VGA CARD. IBM' COMPATIBLE
SPREADSHEET, WORDPROCESSOR & DATABASE
SOFTWAREINCLUDED.
NEW 286-25/31
$1 , 549
TAX INC.
$1595
80386SX-16 CPU
1 MEG RAM EXP TO 8 MEG
21Mhz LANDMARK SPEED TEST
1.2M JAPANESE F.D.D. 512K VGA CARD
85M HARD DISK DRIVE,
101 EXTENDED "CLICK" KEYBOARD
MINI CASE & 200W POWER SUPPLY
SUPA VGA COLOUR MONITOR 1024x768 Res 0.28""DP
SERIAL PARALLEL GAMES PORTS
3 YEAR PARTS & LABOUR WARRANTY IBM'
COMPATIBLESPREADSHEET, WORDPROCESSOR &
DATABASESOFTWARE
INCLUDED.
TAX
• SHAREWARE SOFTWARE
'
INC.
ASSEMBLED & TESTED
$1 695
EXTRA RAM
1 MEG add .. $75
2 MEG add .. $150
DOS 5.0 AN EXTRA ....................... $100
DR DOS 6.00.$129 WINDOWS 3.00.$129
SOUND CARDS
SOUND COMMANDER ..................... $149
THUNDER BOARD .......................... $199
SOUNDBLASTER II ......................... $249
SOUNDBLASTER PR0 ..................... $389
FLOPTICAL DRIVE add ................... $849
21 M/BYTE DISC TO SUIT............... $39
CD ROM DRIVE ............................... $795
RITRON
RITRON
(
(3~6SX-31)
80386SX 25M CPU
1 MEG RAM EXP TO 8 MEG
31Mhz LANDMARK SPEED TEST
1.2M JAPANESE F.D.D. 512K VGA CARD
85M HARD DISK DRIVE,
101 EXTENDED ""CLICK .• KEYBOARD
MINI CASE & 200W POWER SUPPLY
SUPA VGA COLOUR MONITOR 1024 x 768 Res 0.20•• D.P
SERIAL PARALLEL GAMES PORTS
3 YEAR PARTS & LABOUR WARRANTY IBM'
COMPATIBLESPREADSHEET, WORDPROCESSOR &
DATABASESOFTWARE INCLUDED.
'SHAREWARESOFTWARE
ASSEMBLED & TESTED
IN AUSTRALIA.
EXECUTIVE
EXECUTIVE
$1 _
749
'
TAX
INC.
( /.3~~-65 >v
386-57)
80386-33 CPU 64K CACHE ON BOARD MEMORY
1 MEG RAM EXP TO 16 MEG
57Mhz LANDMARK SPEED TEST
85 MEG HARD DISK
1.2M JAPANESE BRAND F.D.D
101 EXTENDED "CLICK" KEYBOARD
SERIAL PARALLEL GAMES PORTS
SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP
MINI CASE & 200W POWER SUPPLY
512K VGA CARD (256 COLOURS) IBM' COMPATIBLE
3 YEAR PARTS & LABOUR WARRANTY
SPEADSHEET, WORDPROCESSOR & DATABASE
SOFTWARE INCLUDED.
' SHAREWARE SOFTWARE
ASSEMBLED & TESTED
IN AUSTRAUA.
$2 095
'
TAX INC.
EXECUTIVE
(486-157.>)
80486·33 CPU
256K ON BOARD CACHE. 1 MEG OF RAM
157Mhz LANDMARK SPEED TEST
85 MEG HARD DISK
1.2M JAPANESE BRAND F.D.D
101 EXTENDED "CLICK"" KEYBOARD
SERIAL, PARALLEL, GAMES PORTS
512K VGA CARD. IBM' COMPATIBLE
SVGA COLOUR MONITOR (1024 x 768 Resolution) 0.28""DP
MINI CASE & 200W POWER SUPPLY
3 YEAR PARTS & LABOUR WARRANTY
SPREADSHEET, WORDPROCESSOR & DATABASE SOFTWARE.
ASSEMBLED & TESTED IN AUSTRALIA.
'
TAX
INC.
WITH 200 MEG DRIVE
$2,945 TAXINC.
$2,450 TAX EX.
$2,895
$2,495
WITH 200 MEG DRIVE
TAXINC.
TAX EX.
ROD IRVING ELECTRONICS Est. 1977.
MAIL ORDER HOTLINE: 008 33 57 57. ORDER FAX LINE: (03) 543 4871 ENQUIRES (03) 543 7877
HEAD OFFICE: 56 RENYER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648
CITY 48 A.BECKETT ST. MELBOURN E. PH. (03) 6391640. FAX: 6391641.
OAKLEIGH: 240C HUNTINGDALE RD, OAK LEIGH. PH: (03) 562 8939 FAX: (03) 562 8940
NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. <189 88M. FAX: 489 8131.
SYDNEY:74 PARRAMATTA RD, STANMORE. PH : (02) 519 3134. FAX: (02) 516 5024
BLUESTAR COMPUTERS:
271 MAROONDAH HWY, RINGWOOD, PHONE: (03.) 870 1800 FAX: (03) 879 3027
115 - 117 PARRAMATTA RD CONCORD. PH: (02)'744 5526 FAX : (02) 744 5405
$2,395 ~:;
WITH 200 MEG DRIVE
$2,895 TAXINC.
$2,495 TAXEX.
TAXEX.
RITRON
EXECUTIV
RITRON
$ 2 195
ASSEMBLED & TESTED IN AUSTRALIA.
$1,995
386-33 12BK..... $2195
80486SX-20 CPU
1 MEG RAM
EXP TO 32 MEG
75Mhz LANDMARK SPEED TEST
85 MEG HARD DISK
1.2M JAPANESE BRAND F.D.D
101 EXTENDED ··cLICK"" KEYBOARD
SERIAL, PARALLEL, GAMES PORTS, 1MEG VGA CARD
SUPA VGA COLOUR MONITOR·(1024 x 768 Res) 0.28" DP
MINI CASE & 200W POWER SUPPLY
3 YEAR PARTS & LABOUR WARRANTY
SPEADSHEET, WORDPROCESSOR & DATABASE
SOFTWARE INCLUDED. 'SHAREWARE SOFTWARE
80386-40 CPU
64K CACHE ON BOARD MEMORY
1 MEG RAM
EXP TO 16 MEG
65 Mhz LANDMARK SPEED TEST
126 MEG HARD DISK 12ms ACCESS TIME
1.2M JAPANESE BRAND F.D.D
101 EXTENDED ··cLICK" KEYBOARD
SERIAL, PARALLEL, GAMES PORTS 512K VGA CARD
SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.20·· DP
MINI CASE & 200W POWER SUPPLY
3 YEAR PARTS & LABOUR WARRANTY
SPEADSHEET, WORDPROCESSOR & DATABASE
SOFTWARE INCLUDED. 'SHAREWARE SOFTWARE
$3,595
$2,995
TAX INC
<at>4.E362t.57 c
80486-33 CPU 256K ON BOARD CACHE. 4 MEG OF RAM
157Mhz LANDMARK SPEED TEST
200 MEG HARD DISK 12ms ACCESS TIME
1.2M JAPANESE BRAND F.D.D
3.5" 1.44M JAPANESE BRAND F.D.D
101 EXTENDED "CLICK" KEYBOARD
SERIAL, PARALLEL, GAMES PORTS
1 MEG VGA CARD. IBM' COMPATIBLE
SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28"" DP
TOWER CASE & 220W POWER SUPPLY
3 YEAR PARTS & LABOUR WARRANTY
SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWARE.
ASSEMBLED & TESTED
IN AUSTRALIA.
IDEAL CAP MACHINE!
'
TAX INC.
TAX EX
FREIGHT CHARGE BASED ON 35KG
COMPUTER SYSTEM
Melb-Metro.$12.00
Sydney....... $17.00
Adelaide .. ... $17.00
Bribane ...... $24.00
Canberra .... $18.00
Darwin ........ $40.00
Perth. •••...•... $31.00
Tasmania •... $53.00
Vic country.... $19.00
NSW country.$39.00
S.A country..• $39.00
OLD country.$55.00
W.A country.• $74.00
lnsurance:$1 / $100 Value.
$ 3 99 5
$3,395 TAXEX.
All sales tax exempt orders
to : RITRONICS WHOLESALE
56 Ronvor Rd, Clayton, Victoria.
Ph: (03) 543 2166
Fax: (03) 543 2648
MAIL ORDER & CORRESPONDENCE
P.O BOX 620, CLAYTON, VICTORIA. 3168.
Error• & ommlnon, excepted. Prtcn & apeclflc1tlons
eub/eet to change. "IBM, PC, XT, AT, are registered
trademark ■ of lntem atlonal BualneH Machlnee.
PRICES AT AUS S ■ US $0.74
1·9 boxea 10+
31/2"DD $19.95
3 1/2"HD $45.95
5 1/4"DD $14.95
5 1/4"HD $23.95
ETIME WARRANTY
50+
$4.30
$8.10
$7.50
$13.50
100+
$3.25
$7.50
$7.00
$12.00
SOO+
$3.95
$6.90
$6.60
$11 .00
~
RS232 2WAY.......... ........ $39
RS232 4 WAY.................$59
RS232 X OVER .............$59
RS232 2 WAY A UT0 .....$69
CENT RO NICS 2 WAY... .$39
CENTR ONICS X-OV ER .$59
CENT RONICS
2 WAY A UTO.$69
CENTRONICS 4 WAY.$69
D89 + 5 PIN DIN ....$69.95
VGA KEYBOARD
SWITCH BOX
2 WAY............... ...... $59.95
4 WAY...................... $69 .95
9 PIN SWTCH BOX
2 WAY.................... .$49.95
4 WAY..................... $59. 95
10+
3
3
5
5
1/2"DD $28.50
1/2"HD $53.50
1/4"DD $22.95
1/4"HD $27.95
NEW CATALOGUE OUT NOW!
NEW SWITCH BOXES
VIDEO SWITCH BOX
$18.95
$42.95
$12.95
$22.95
MOTHERBOARDS
$27.95
$52.50
$21.95
$26.95
3 1/2"DD $23 .95
3 1/2"HD $39.95 $
5 1/4"DD $12.95 $
5 1/4"HD $19.95 $
PA
COLOUR
MONITOR
3 YEAR WARRANTY c::::::::::v""""
286-12/16 .............ir...·=··················$1 09
286-16/21 ........... ._j -~·,,.--,. •·
........$159 This stylish & reliable monitor has been
386SX-16 ........... ·
,. .......$295 designed for Australia n conditions and
1
386SX-20/27 .....
•• , •.•':::::: :'. . . . . . . . . $325
comes with a 3 year warranty.
386SX-25/31 ................................... .$350 , Spees: CTR: 14" 90° delection, dark tint,
385-25 .............................................. $525
non glare.
386-33 64K CACHE......................... $645
Display Size : 245 +/5mm x 180+/-5mm x
386-33 WITH 128K CACHE ............$749
180+/•5mm
486SX·20 .........................................$895
Resolution: (max): 1024 x 768
486·33 256K CACHE....................... $1295 Dot Pitch: 0.28" ...... $469.00
SOUND BLASTER II
With FREE speakers
The ultimate sound card that plugs into ant
internal slot in your IBM or compatible
• Spech to text syntheseizer & more........ $229
•
•
SHORT OF SLOTS?
.
SOUND BLAST R PRO
16 Bit Card
• RCA Aud io cable • Midi Cables
• 5.25" & 3.5" diskettes
• CD music player & much more .....•...... $469
"NEW" IBM VGA-COMPATIBLE VIDEO
GRAPHICS CONTROLLER
Comes complete with :
, VP442 Card
• Users Manual
, 2 Diskettes (driver & ut ill ity)
• Two 10 to 9 /25 interface cable for COM 1 & COM 2
, 34 way Flat cable for FOO
• 40 Way flat acble for IDE
• 16 to 15 interface cable for GAMES PORT.
X18066 .....................................................................$139.00
SAVE ON OUR GREAT RANGE OF EPSON PRINTERS
Matr i x, 180 Cps Dr aft
30 Cps NLO, Pu ll Trac tor
C22054 ................... $249
LX·SS O 80 Co l. 9 Pin Do t
Malrix , 240 Cps Dr aft
LQ •860 80 Col. 24Pi n Doi Matrix•
295 Cps Drall.98 CPS LO. Colo ur
SQ -25S0 BO Col , 24 Nozzel
LX•40 0 80 Co l. 9 Pin Do t
tQ~
i nk jet, 600 Cps Draft, 198
Cps LO, Push Tractor,
Smart Park Featu re ,
Standa rd,Push Tractor Smart Park
Feature ................................... $1095
..............$1995
LQ-1070 136 Co l. 24 Pin Dot
Matri x, 252 Cps Draft, 84 Cps
LQ •400 80 Co l. 24 Pin Do t
48 Cps NLQ, Pu sh Trac tor,
Sm art Park i-:ea tu re
Matrix, 180 Cps Draft , 60 NL O
NLO, Scal ab le Fonts, 8 to 32
Pull Tractor
po int, 11 LO Fon ts, 360 x 360
C22074 .................... $3 65
C22070 ..................... $4 39
FX· SSO 80 Col. 9 Pin Dot
Ma trix , 264 Cps C'r a h
LQ-570 80 Co l. 24 Pin Dot
Matrix, 252 Cps Draft, 84
54 Cp s NLO Pu sh Trac tor
Sm art Pa rk Fe&ture
Cps . NLO Scalable Fonll
8 to 32 points, 11 LO Fonte
360 x 360 DPI. Top. Rear•
Bottom and Fro nt paper
...$750
FX• 1050 136 Col. a Pin Dot
Ma trix. 264 Cp s Draft. 54
Cpa NLQ, Push Tr1ctor1
Smar t Park Fea tura.
·•· ··•· ·....... .................... .. $925
SQ •85 0 80 Col. 24 Nozzo l
Ink
GOO Cpl Dri ll. 1118
Cpl LO. Pul h Trac tor.
Smut Pe rk Foaturo.
i••·
.................................... $1, 225
DPI, Top, Re ar, Bottom, and
Front Paper Feedpaths,
Convenable Push/Pu ll Tr actor
·························· ..............$775
LQ• 1170 136 Col. 24 Pin Doi
Matri x. 350 Cps Drafl. 110 Cp1
NLO. Sc1l1ble Fonll. 8 to 32
poin~ 11 LO Fonll. 360 x 360
DPI. Top. Rear. Bottom. I nd
Front Poper Feedp1th 1•
Convel1 oble Pu 1h/Pull Troctor
feed pa th,, Con vertable
Pu1h/Pull Tr1e1or.
.................................. $575
........................................ $1,149
LQ•870 80 Col. 24 Pin Dot
Motrlx.330 Cp1 D,.fL 110
Cp1 NLO. Scalab le Fonta.
a to 32 pol n11. 11 LO Fon11 .
360 x 360 DP I. Top. R11r.
Bottom. & Fro nt pop11 FNd
palhl Convtrtlbll Pu1h/Pull
Tractor .
LQ•l 060 138 Col. 24Pln Dot Matrix'
292 Cp1 Drott, 98 ;;pa LO. Colour
Standard.Pulh Tractor. Sm1J1
Park Future.
............................................ $1,395
...................................... $895
LQ•2550 138 Col. 24Pln Dot Matri x'
LQ •200 60 Col. 24 Pin Dot Matrix
192 Cpa Drafl. 84 LO. Pu ll Tractor.
a Bit Mop lonll.
400 Cp1 Draft, 133 LQ Colour
Sta ndard.Pulh Tractor. Sm111
Pa rk F11turt •
.......... .................. .............$475
• ACN.005 428 437
HE.AD OFFICE: H RENVER RD, CLAYTON. PH: (03) 543 21H. FAX (03) 543 2848
CIT'i 48 A•BECKETT ST. MELBOURNE. PH. H3 8351 / 8381840. FAX: 8381841.
OAKLEIQH: 240C HUNTINQDALI! RD, OAKLEIQH. PH: 582 8838
.
NORTHCOTE 425 HIQH ST. NORTHCOTE, PH. 488 88H. FAX: 488 8131 .
IYDNl!Y:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 519 3888
BLUESTAR COMPUTERS: 271 MARCCNDAH HWV. RINGWOOD. PH: (03) 170 1800
.........................................$ 2,049
Po1tag1 r1t11
., ............ u.oo Tit•• ,....,.
. 10 • f24.99.,'3.50 11ltllN bHII
'21 • '49.99 .. '4.50 potltge only 11P ••
'50 • "9.99 .. H.OO
: •::,i:lgh~
,100 • ,199 .... 7.00 llomt wtNIla
:~lty
,200 • 8100... FREE
8100 PLUI .. FREE
oharg• ~ 11111-t
11 • 1
HO
~
WELLER
SOLDERING
STATION
~ c ·~
with temperature
controlled soldering iron.
I~-·
CD ROM DRIVE UNIT
\Q·~),C::~,:./
A tramsformer powered soldering station, complete with a low voltage,
temperature controlled soldering pencil . The special Weilar "closed loop"
method of controlling maximum tip temperature Is employed, thereby
protecting temperature sensitive components while the grounded tip
protects voltage and current sensitive components. The soldering pencil
features a stainless steel heater construction, a non-burning silicon rubber
cord and a large selection of iron plated tips in sizes from 0.8mm diameter
to 6.0mm diameter with a choice of tip temperature of 315° C/600°F, 370°
C/700° F and 430° C/800°F.
r12soo Usually $179.00 This month o nly $129.00
ioouble your disk
.storage with ....
.•.
-g
.
a
Open up a whole new world of sight and sound user interaction with a CD-ROM Drive
Unit You have never seen such a wealth of lnfomation and entertainment with audio
and visual response that will truly astound you. You can even play and listen to your
audio CD'S while continuning to use your computer
The world of the CD-ROM makes available to you over 1,500 CD-ROM Titles produced
by more than 1,800 companies which support this fast growing information and
entertainment facility.Comes complete with CD ROM DRIVE UNIT, controller card for
installation In an IBM PC.2
SPECIFICATION
PERFORMANCE
Disc diameter..............................12cm
Disc speed .................................. 200-530rpm (CLV)
Da!a capaclty.. .............................540 MBytes
Da!a transfer Rate
Sequentlal..1 SOKBytes/sec. (Mode 1) 171 KBytes/sec. (Mode 2)
THE POWERMATE
"GREAT 8"
DR DOS 6.0
The most advanced, fully DOS-compatible
operating system available today. lt•s
everything you need to nm your DOS, Windows,
and networking applications faater.
Maximize hard disk performance, keep your system
and Data secure, and make your PC easier to use.
DISK MAX: Improves your pc•s overall performance so you can get more work done In
less time. lta optional automatic file compression feature potentially doubles your hard
disk storage space.
MEMORY MAX: moves ·DR DOS buffers, drivers, TSRs and networking software outside
the 640K memory area, leaving more memory for your DOS, Network and Windows
applications.
Ideal for the garage or home. The Powermate
"Great 8" has 8 outlets for all types of
appliances plus ii provides extra safety. It has
Overload protection. If it is overloaded
(operating appliances that totally exceed 2400 watts or 1 O amps). The
overload swlch will trip, automatically turning off all appliances plugged
Into the Powermate. If it does overload you simply push the reset bullon
THIS MONTHS PRICE IS THE LOWEST YET!.. ......
P18044 .......................................•...••.........•. ........ $39.95
CITIZEN™ PN48™
$99.00
and power ls restored.
lH\5 MON1~
-!,~~-·;:·~-=::::=::=====:,7' 4164-10
: .: : ~,~ o~ : : : : :,::~~~s,: :,e__:_te-rs-.
Z•
The PN48 Notebook Printer Is the first printer
I
that is every bit as portable as the new· notebook
• ·· ·
computers. Weighting approximate ly two pounds
■
without the battery (2 1 /2 pounds with the battery),
you can add the PN48 to your portable office and hardly know it•s there.
PN48 FEATURES:
Despite the remarkable small size (11 518" x 3112"), the PN48 is the worlds first
truly portable laser quality printer, offering the same versatility and superior
printing quality made famous by other Citizen printer. The Notebook Printer is
compatible with Citizen CSX- aeries 24-wire printers. Has two built'i n fonts,
Roman and Courier; five pitch selection; and the ability to print on overhead
projector transperancies. You will find the PN48 easy and fun to use. 1t•s simple
to operate, connecting your computer Is a snap, and both print cartridges are
designed for long and dependable trouble free wear.
• Graphic resolution as high ea 360 x 360 dpi:
C22199 ........................................
$699
1Mx9
;)
CORDLESS
/
ELEPHONE
AUS
~/
~
,K----....-::~
G ~---- .- .·
FEATURES:
• Full Two-way Intercom
• Paging
• User Selectable Security Coding
• Tone/Pulse Switchable
• Last Numder Redail
• In-use Indicator
• Automatic return lo standby mode when
remote phone is in charge
A94200 ........................was $17Q,QQ
Special MAY price $169.00
Speed (ns) No. of pins
1-9
100
(64K X 1)
$4.95
80
(4 X 64K)
$6.95
41256-08
(256K X 1)
80
$3.95
44256-07
70
(256K X 4)
$9.95
lM-10
(1Mx 1)
100
$10.95
lM-08
80
(1Mx 1)
$12.95
Speed (ns)
SIMMS
1-9
10+
256K X 9
80
$21.00
$19.00
1M x 9
80
$79.00
$75.00
1M x 9
70
$79.00
$75.00
1-9
10+
4M X 9
80
$295.00
$275.00
Speed (ns)
SIPPS
1-9
10+
256 X 9
80
$21.00
$19.00
1Mx9
80
$79.00
$75.00
) 4464-08
70
$79.00
$75.00
10+
$4.50
$5.95
$3.50
$8.95
$9.95
$10.95
100+
$2.90
$3.50
$2.50
$8.50
$7.95
$8.95
100+
$18.00
$69.00
$69.00
25+
$250.00
500+
$16.00
$59.00
$59.00
100+
$18.00
$69.00
500+
$16.00
$59.00
$69.00
$59.00
1000+
$2.25
$2.95
$1.95
$6.95
$7.50
$7.50
CODE-A-PHONE
PERSONAL ANSWERING MACHINE
FEATURES:
•"BEEPLESS" Remote Control
• Call Screening
• One-Touch Message Playback
• Personal Memo Record
• Voice-Activated Recording
• 10 Number Speed Dailing
• Power-Fail Security
• Digital Message Counter
• Fast Forward Rewind
• Built-in Microphone
• Ring Selector
MESSAGE LIGHT
MESSA GE COUNTER 7
,... STOP
~
MESSAGES
RINGER
_
Auro..J i ,
NN REC
- o1ALPA0 iuNoeR cAssene cov
A94150 ............... was $~QQ.QQ LNO J , o,REcrosv
Special MAY price only $1.79.00
.• . .
-
.-
'
·'
. ST·UDE.NT .SOFTW,AR.:E. PAC-KAG.ES
WORDPERFECT WINDOWS ..
If your a FULLTIME student MS WORD WINDOWS .......... ..
or teacher with current
MS EXCEL WINDOWS ........... .
CORAL DRAW........................ .
identification from the
VENTURA PUBLISHER ......... .
education institute you
DBASE IV................................•
attend, you can take
BORLAND C++ ....................... .
advantage of these great
BORLAND C++
prices on this popular
WITH APPLICATIONS ............ .
software!
ADL,US PAGEMAKER ............ .
GET INTO THE PICTURE WITH THE MAESTRO
.
9600XR FAX/ DATA MODEM . .
J
•
-
SPECIFICATIONS V29 / V27 ter / V21 Ch.2 Fax modes
V22 bis V22 / Bell 212A 103 Data modes Auto dail,
Auto Answer, Pulse and Tone Dialing, Hayes "AT'
compatible, TR.29 fax mode compatible (industry
standards), Fax group 3 compatible (send and
recieve), Auto Baud select, All new dsp technology,
External modem-RS232 compatibles and Apple
Macintosh.
MAESTRO 2400XR MODEM
This is our biggest selling
external modem that features•
V22 bis, V22 , V23 (with auto
BRC), V21· (2400bps,
1200bps, 12oonsbps,
300bps) Auto Baud Select,
Hayes "AT"·commands set,
Auto Answer, auto Dial,
Auto Disconnect. This modem
will suit almost any computer
with a RS232 serial port.
Telecom approved.
2400bps for only $389.oo
This has to be the cheapest and
easiest way Into high speed data
communications with features
only found .i n some moderms of at
least twice the price. Features
include-2400bps (V22bis), 1200bps
(V22),
Auto answer, Auto dail, Auto
disconnect, Hayes "AT"
commands set compatible, Non
volitile memory (for configuration
storage), Synchronous and
Asynchronous operations
Telecom approved
$289.oo full price incl. tax
"MegaRAM" Memory board
This new generation memory enhanced board
offers O wait state high speed operation . •
It takes• up to 6M Bytes of 4 x 256K or 1 x
1 M DRAM chip. Up to seven cards can be used together (42M B EMS).
It is 100% EMS 3.2 & 4.0 compatible, and best of all it can be used in an
XT, AT or 386 because it is 8 bit, 16configerable. So get yourself a Mega
tor the price of a mini.
x1aos1 .. .............. ......... SAVE sso.oo........... $249.oo
$210.00
$.290.00
$296.00
$399.00
$395.00
$295.00
$235.00 ..._
$285.00
$395.00
AUVA
NOTEBOOK
The Ritron 945/20 takes up less
space than your old desktop
when you 're working and can be
stored in the drawer of your desk
when you're finished. The 945/20
uses less than one third of the space
of your desktop SX and Is at least as
powerful. Don't stretch your arms
to their limit walking back to the
office. The Ritron 945/20 wont drag
you down when you need to be on•
the•go Relax over a cup of coffee
and do some power computing in a
more elegant setting than your
office. The Ritron 945/20 lets you
work in your favorite places without
intruding on everyone around you.
Microprossor
'CPU 80386SX·20
Memory
'Fitted with 4MB
BIOS
'128KB ROM Pheonix BIOS
Storage Devices
'One 1.44MB 3.5" Floppy disk·
drive
' Ona 60MB 2.5" Hard Disk Drive
Display
'VGA compatible display
'640x480 pixel res olution
'32 gray scales
•Backlit Paper White LCD
INCLUDES DOS 5
OR DR DOS 6.0
ALL FOR ONLY
$2895 1nc. Tax
$2495 Tax Ex.
4 PORT SERIAL CARD
(Software Output Cables included)
The PE. 514 has 4 port serial ports for
asvnchronous communication. These
ports can bve used to connect your PC
with a serial printer, MODEM, Serial mouse
or serial devices which use an RS232C interface.
The interface Is a DTE type with a male DB25P for
4 serial port output. It supports DOS & XENIX.
X18155 ...............................,...... $199.00
=:;===============================::; ;:;;:;:;;:;::~;:::::;;:;;;==============-=======:::::....
,~i,~~~
°;~;;~::~\ m~~i~i::RDc~
scanner that can transfer graphic
:Jl.RJi:1
~• .:·___)····
images such as photographs, drawings, - - - ~
~
text and clip art d irectly to your computer screen. It Js capable of
scanning up to 105mm in two ditterent modes, Letter or Photo.
The GS-4500 also has a resolution control switch lo select Iha amount
of brightness to be used.
It also can control Iha amount of colour shade. Tha letter mode scans
black and white This mode can be used for artwork and scanning text lo
a text file using OCR software.
X19935 ................................ $279.00
~
The ULTRA 15C provide• Intelligent caching up to 16 MBytee of cache memory to make the
drive "lnvl1lble" when a cache hit le achieved providing multiple lncre11e1 In 1/0
performance. It lo AT regieter & BIOS compatible. It 1upport1 two high transler IDE drive,. It
1upport1 the lergeet ■e lection of hard drlveo In the m,rket today. The ULTRA 15C 1110
aupporll any mix (s. 25.. and 3.5") of up to three floppy dlek drlveo or floppyt ■ pea. In
addition to the apeclal oupport to break the oupport to break the 1024 cylinder and the
528MB partition limit■ of DOS ind OS/2, the ULTRA family of caching controllero will 1 110
co-reolde with any other controller to aupport dual channel• and/or duplexing/mirroring in
popular network operating ayateme.
ty. t .
•············•·•···•••••·········•··· ..
ROD IRVIN
ACN.oos 428 437
HEAD OFFICE: 56 RENVER RD, CLAYTON. PH: (03) 543 2186. FAX (03) 543 2648.
CITY 48 A'BECKETT ST. MELBOURNE. PH. (03) 663 6151 / (03) 639 1640. FAX: (03) 6391641.
OAKLEIGH: 240C HUNTINGDALE RD, OAK LEIGH. PH: (03) 562 8939. FAX:,(03) 582 8940.
NORTHCOTE 425 HIGH ST. NORTHCOTE, PH.(03) 489 8868. FAX : (03) 489 8131.
SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. or (02) 565 1458. FAX: (02) 516 5024.
BLUESTAR COMPUTERS: (COMPUTER PRODUCTS ONLY) 271 MAROONDAH HWY. RINGWOOD. PH: (03) 870 1800. FAX: (03) 879 3027.
OPENING 6th OF APRIL: BLUESTAR COMPUTERS CONCORD. (COMPUTER PRODUCTS ONLY)
GROUND FLOOR 115-117 PARRAMATTA RO, CONCORD. PH: (02) 744 5528. FAX: (02) 744 5405.
TOLL FREE MAIL ORDER HOTLINE: 008 33 5757. FAX ORDERS: (03) 543 2648 (STRICTLY ORDERS ONLY)
$649.00
::a .
, 195mm length
H10542 ....................... $15.50
, 200mm length
H10543.......................$15.90
• 225mm length
H10546 ....................... $16.90
• 300mm length
H10560 .......................$19.00
, 1 metre length
H10565 ....................... $49.95
• 2 metre length
H10570 ....................... $95.00
10+
P10525 ............$7.95 $6.95
6N138 ·OPTOCOUPLERS
Z11660 ..................... $6.95
CANON LASER
CARTRIDGES
'
TI P 120
T90517 .....................$2.90
,_
-
TEA 2000 PALJNTSC
ENCODER
U10175 .................. $15.00
INS 16550 AFN UART
U221 87 ..................$23.95
NEW IC MC34 063
U10416 ................... $2.95
As seen In Silic on Chip's
Solar Battery Charger kit.
2 UNI VE RS IAL BRACKETS
WITH SC REWS TO MOUNT
3 1/2" HARD DR IVES
INTO MOST CO MPUTER
CASES
X19971 ...................$9.95
Why waste your precious
time & money
trying to get a quality print
out from a "recharged"
cartridge when you can buy a
brand new Canon Laser
cartridge from Rod Irving for
only $199.00
EP CARTRIDGE FOR SIDE
LOADING PRINTERS
C21107..............$199 .00
EP•L CARTIDGE FOR
FRONT LOAD ING
PRINTERS
C21109 ............... $199.00
EP-S CARTRIDGE FOR TOP
LOADING PRINTERS
C21108 ............... $199.00
BJ CARTRIDGE
BC-01
CANON BJ CARTRIDGE
BC-01
FOR BUBBLE JET
PR INTERS
C22218 .............. ......... $ 55.00
RADIAL FIN
HEATSINKS
TURNTABLE ··
REPLACEMENT
BELTS
-~-d~
;,j
TB5.DIA.185mm
WIDTH 5mm
LENGTH 581 mm
A17006 .................... $4.95
TB10.DIA.189mm
WIDTHSmm
LENGTH 593mm
A17007.................... $4.95
TB15.DIA.195mm
WIDTHSmm
LENGTH 612mm
A 17008 .................... $4.95
TB20.DIA.205mm
WIDTH 5mm
LENGTH 644mm
A17009 .................... $4.95
TB5.DIA.185mm
WIDTHSmm
LENGTH 581mm
A17006 .................... $4 .95
TB25.DIA.210mm
WIDTH 5mm
LENGTH 659mm
A17010.................... $4.95
BUDGET
SOLDERING IRONS
~
Rating 1' C/Watt 150mm
Length
Des igned by Rod Irving,
SCREWDRIVER TIP
SOLDERING IRON
, 240V
• 30mm length
H 1o52 o......................... $s. 9 o
• 75mm length
, 15 WATT
T12907
$16 95
........ ................
·
H10 52 5 ......................... $7 .9 o
PO INTED TIP
SOLDERING IRON
, 240V
, 15 WATT
T 12905
WAS
~
THIS MONTH 0NLv.:·s12.95
DIRECT IMPORT
PRODUCT! YOU SAVEi
DOU BLE
P10538 ............... ......... $6.95
Th e11 are good quality
SIMM Socket ■ w ith metal
cllpe at th1 enda and not
t h e p laetlc on11 which
• 100mm leng th
H10529 ......................... $8.90
• 140mm length
H10534 ....................... $11 .50
• 150mm length
H10535 ....................... $ 12· 95
brHk,
• 170mm length
H10538 ....................... $14.95
MAIL ORDER
·HOTLINE:
008 33 5757
FAX HOTLINE,
(03) 543 264B
These pin!- are not gold
plated so they are much
cheaper.Thay are su itable
for wire wrapping and flt
holes of 1mm (0.04In)
diameter. Two types are
available Sing le-sided and
Double-sided
0
LAMPS & GLOBES
Our range of lamps and globes
have colour coded wires to
denote what voltage they are
rated at:
Red wires:
White wires:
Blue wires :
6 volt rating.
12 volt rating.
24 volt rating.
CLEAR SUBMINIATURE
GLOBES
DOUBLE SIDED
Packet of 20
H11680 .......................... $3.95
Packet of 100
H11681 ....................... .$18.95
Packet of 500
"""'·· ~ "-"
Anodized B lack Thermal
~·
£::
"
WIRE WRAP PINS
SINGLE SIDED
Packet of 20
H11690 .... ...................... $3.50
Packet of 100
H11691 ........................ $17.95
Packet of 500
H11692........................ $79.95
ARLEC DIGITAL
SCALES .
S14000............... 6V/80MA..... $0.80
S14001 ............. 12V/85MA..... $1.25
S14002. ............ 24V/50MA..... $1.25
• Dimentions: 6.3mm (L) x
3.2mm(Dia)
• All have 120mm wire leads
CLEAR SUBMINIATURE
GLOBES
S14003. ............. 8V/80MA ...... $1.25
S14004............. 12V/85MA..... $1 .25
S14005............. 24Vi50MA ..... $1.25
• Dilnenliona: 10mm (L) x 5.1mm
(Dia)
• All have 120mm wire leads
<C:Qtiiw~
ROUND GLOBE •
BAYONET BASE
S14006......... 12V/50mA ....... $0.95
• Dlmentiona: 23mm (L) x 11mm
(Ola)
• Clear glaae lena.
~~~
ROUND GLOBE,
SCREW BASE
ELECTRONIC
K ITCHEN SCA LES
• Si mply converts grams to
ou nces and ounces to
grams by switching the
selector key.
• Various Items can be
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Computing On
The Big Screen
Forget about CAD & desktop publishing on a small
screen. To really work with these programs, you need a
large-screen, high-resolution monitor.
By JIM SHARPLES*
The recent popularity of
others , such as desktop pubGUis (Graphical User Interlishing, CAD and graphics,
faces) and WYSIWYG (What
larger screens are almost a
You See Is What You Get)
necessity. If you try doing a
has resulted in a marked
2-page layout in PageMaker
decrease in the prices of
or Ventura, for example, the
monitors, particularly the
resulting display is practicolour models.
cally unusable. Or what
The advent of Windows
about trying to design a
3.0 in the IBM PC compatlarge double-sided board on
a small screen. It is possiible market has created a
ble but not the most effihuge demand for colour
cient way.
monitors capable of dis playing higher resolutions
Colour or mono?
than ordinary VGA. These
higher resolutions are reEighteen months ago the
ferred to as "Super VGA"
price gap between colour
and can not only display
and monochrome monitors
the 640 x 480 pixel resoluwas fairly substantial and
tion of standard VGA , but
if the application didn't abThe Philips 4CM2799 20-inch colour monitor supports
also 800 x 600 and 1024 x
solutely require colour, then
resolutions up to 1280 x 1024 & can be used with a wide
768 resolutions. Many of
monochrome was certainly
range of video driver cards.
the larger monitors also supthe most economical purchase. Now, however, the
port 1280 x 1024 but there
there is a corresponding demand for
are not (yet) many video cards able to
price gap has narrowed to the point
larger monitors. It's very nice having
where monochrome would not be a
display at this resolution.
a 14-inch monitor displaying Win- wise choice, particularly as many
Most of the recent monitors are the
"multisync" type; ie, they synchro- dows or CAD (Computer Aided De- newer programs rely on colour to make
sign) in 1024 x 768 resolution but
nise at multiple frequencies. This
them easier to use. Menus, grids, tools,
everything is so small! Just try using a
icons, selection areas and many asmeans that IBM compatible users
14-inch monitor, swap to a large moniaren't the only ones to score - Mac,
pects of the programs use colour to
tor for a week or so, then return to the
Amiga and other computers can use
make the user's job more instinctive
14-inch monitor. You'll really miss
and obvious.
the same monitors.
that large screen.
Windows 3.0 is a good example.
Larger monitors
For some applications, the smaller Whereas Windows 2.0 hardly needed
size is not much of a problem but for
With the increase in resolution,
colour and indeed, it was just a 1uxury,
16
SILICON CHIP
Windows 3.0 was designed to use colour. In fact, it is somewhat difficult to
use quite a few applications in monochrome!
CAD is another software category
where colour is almost essential, particularly with multi-layered applications such as circuit board design.
Drawings quickly become confusing
and hard on one's concentration.
But what about the difference in
quality between monochrome and
colour? Let's face it - monochrome
will beat colour hands down in a contest where resolution is the same. It's
much easier having one electron gun
than trying to align three at once.
Again, things are changing. The
resolution of colour monitors is improving all the time, to the point where
it doesn't really make that much of a
practical difference, and in any case
the advantages of colour outweigh the
clarity of monochrome.
How large?
OK. We've decided on a large colour monitor. What is the best size to
go for? Well, here's where personal
taste steps in. In my view, a 17-inch
monitor is ideal for the broadest range
of applications, whether they be textbased (eg, wordprocessing or database under MS-DOS) or graphicsbased as in Microsoft Windows. Text-
based applications can be rather overpowering when viewed on a 21-inch
monitor, unless you happen to be very
short-sighted, in which case they are
a great idea. I know of one person
who bought a 20-inch monitor for this
very purpose.
(By the way, notice how we still
persist in measuring monitor diagonal sizes in inches? Obviously, this is
the strong influence from the American computer industry).
17-inch monitors
As mentioned, this is the best general purpose monitor size. They have
the added advantage of taking up a
little less space on the desktop, though
even a 17-inch monitor seems huge
after a standard 14-inch one. There
haven't been many of this size monitor around until a recent flurry of
announcements by various manufacturers. It seems they all suddenly realised that this would be the logical
choice for many users and announcements have been appearing hard on
the heels of one another.
Another curiosity is that they have
appeared with almost the same specifications: flat screen, 1280 x 1024
maximum resolution, 0.26mm dot
pitch and very similar horizontal and
vertical scan rates and bandwidth.
These specs are pretty good for this
A video glossary
Autosizing: this is the ability of the
monitor to maintain a constant image
size across different video modes.
For example, this is important when
entering Windows in 1024 x 768
non-interlaced mode from the normal
DOS VGA mode. If this is not
available, either automatically or as
a user-programmable option, then
the user must change the size and
position of the image every time
another mode is entered.
Dot Pitch: the distance between
the holes in the shadow mask in a
colour monitor. The shadow mask
(which sits behind the screen) ensures that each electron beam (from
the red, green and blue guns in the
tube's neck) hits the correct dot in
each triad of red, green and blue
phosphors. The smaller the dot pitch,
the finer the grain of the image.
Horizontal Frequency: how often
the monitor scans a horizontal line,
measured in kHz. VGA is standardised at 31.SkHz, while Super VGA
varies depending on the vertical refresh rate of the graphics adaptor.
Multisync: a term originated by
NEC to indicate that the monitor
can synchronise to any horizontal
line frequency within a given range.
Some cheaper monitors are actually "multiple fixed frequency" which
means that they synchronise to particular modes, usually VGA 800 x
600 and 1024 x 768.
Pixel: the smallest triad or group of
triads, depending on the resolution
selected.
Triad: a triad comprises three phosphor dots - red, green and blue arranged in a triangle. Each of the
three electron guns is assigned a
particular colour and that gun excites only its own phosphor dot in
the triad. The combination of excited dots determines pixel colour.
Vertical Frequency or Refresh
Rate: how often the monitor scans
a compete screen, measured in Hz
(cycles per second). The higher the
refresh rate, the less flicker is noticeable. Standard VGA has a vertical frequency of 60 or 70Hz, while
Super VGA should be an absolute
minimum of 56Hz but preferably
70Hz or higher.
This 19-inch high-resolution monochrome monitor from Radius is ideal for
desktop publishing & graphics design. It is fully VGA compatible & can be used
with either PC or Macintosh systems.
Video Bandwidth: the highest video
input frequency the monitor can accept, measured in MHz. This determines the maximum resolution .
MAY 1992
17
size of monitor and should make them
a popular choice.
benefit from a larger view of all those
figures .
19 & 21-inch monitors
Portrait & 'full page' monitors
These are the big ones, needing
plenty of desk space. Don't try to use
them on a narrow desk - you'll land
up with the keyboard in your lap!
And do a weightlifting course before
moving the monsters. They are definitely in the heavyweight class.
Once in place however, the view is
worth it. Both graphics and text are
easier to see and manipulate, reducing the need to zoom in on working
details. There is a corresponding saving in screen redraw time between
the zoom levels. Monitors in this class
usually have a 0.31mm dot pitch,
which is quite acceptable, though
some go as low as 0.28mm:
This is the ideal monitor size for
those working almost exclusively in
high-resolution graphics mode,
whether it be CAD, desktop publishing, animation or even large spreadsheets. Maybe accountants could also
What is a 'full page' monitor? A
number of times I have been asked to
recommend a monitor to fit this vague
notion and when pressed to clarify
the request, the customer usually answers: "a monitor that displays an A4
page". My answer is almost always in
the form of another question: "What
size would you like your A4 page to
be?".
The person wanting a full page
monitor usually needs it for a desktop
publishing application and I have to
point out that even a 12-inch monitor
can display a full A4 page. But if they
want it displayed full size, the options are limited and are pretty expensive.
I also point out that unless they are
working solely on publications where
only a single page view is necessary,
the portrait or 'full page' monitor can
be a liability when viewing two pages
fllc
Edit
l2plloni ,eage
Iypc
Elemcnl
Window
Help
J
Computirig'On
•I
The l3ig Screen
Forget about t,AD & desktop publisll.Ufg on a small
screen. ToreaD~ work ~ilhthesep~og,JpDl~,youneeda
large-screenh,gh-resolution "f°:nil'or.
~:,- JIM SHARPLES
'
These two captured screen images
from PageMaker show how much
more information is displayed at
higher resolutions. At top left is a
1280 x 1024 display, while at bottom
right is a 640 x 480 (standard VGA)
screen capture. The text is directly
readable on-screen in the highresolution mode but has "Greeked"
in the low-resolution mode.
18
SILICON CHIP
side-by-side, or using other applications.
The only exception to my prejudice against portrait monitors is a
rather curious animal - the Radius
Full Page Pivot monitor. This colour
monitor acts as its name suggests - it
pivots between portrait and landscape
modes, using software drivers to
change the orientation when the monitor is pivoted. Portrait mode can only
be used in applications for which a
driver exists and these include some
CAD, wordprocessing and spreadsheet programs, plus Microsoft Windows. A Mac version is also available.
The Pivot measures 15-inches diagonally, so it does not really fit into the
"large monitor" category.
VESA & Swedish standards
The Video Electronics Standards
Association has defined standards for
Super VGA signals to reduce flicker.
This can be particularly noticeable
when the screen background is white,
as in Microsoft Windows. The official
standard requires the vertical refresh
rate to be 72Hz at 800 x 600 resolution
and 60Hz at 1024 x 768 resolution.
Both monitors and video boards must
be able to conform to or exceed these
standards.
Sweden's National Board for Measurement and Testing (MPR) has pub-
A 17-inch colour monitor is a good compromise between size & cost for many
applications. The multi-sync CMl 7MBD from Tatung features 0.26mm dot pitch,
1280 x 1024 resolution (max.), a flat dark-tinted CRT & a microprocessor-based
control system for automatic screen configuration. It can be used with a wide
range of driver cards for both PC & Macll computers.
lished standards for monitor emissions, designed to reduce health risks
and eye stress. Many manufacturers
are designing monitors to conform to
the standards, though there is still
some controversy over the supposed
health risks.
Video graphics boards
When discussing high resolution
monitors, one part of the equation
that cannot be left out is the board
generating the screen graphics, and
here I will restrict discussion to PC
compatibles. A series of simple calculations will show these results:
Resolution
640 x 480 (VGA)
800 X 600
1024 X 768
Pixels
307,200
480,000
789,504
It is obvious that at the common
high resolution of 1024 x 768 the
number of pixels is over three-quarters of a million! And the poor graphics board has to frequently redraw
most of them! Standard VGA has a
limit of 16 colours, whereas high resolution boards can usually generate 256
colours. This means that the high resolution board is manipulating five times
as much information as VGA.
The question of which graphics
board to use is therefore an important
one if you want your screen updates
to happen at an acceptable pace. Basically there are two types of high-resolution boards: those with graphics
coprocessors and those without. The
most popular and possibly fastest of
the boards without coprocessors are
those based on the Tseng Labs ET 4000
chipset. Apart from Tseng Labs themselves, quite a number of manufacturers produce boards using this chipset.
A better option for those using large
monitors at high resolutions are the
coprocessor based boards. IBM ini-
The Radius Pivot Display System is
a colour monitor that pivots between
portrait & landscape modes to suit
your application. Versions are
available to suit both the PC & the
Macintosh family.
tially produced the 8514/A coprocessor for 1024 x 768 interlaced resolution and others have subsequently
cloned this chip, adding extended features like 1024 x 768 non-interlaced
and higher scanning frequencies (see
glossary for an explanation of some of
the terrris).
Another popular coprocessor is the
Texas Instruments TMS34010 and
TMS34020, and boards designed
around these chips can respond to
TIGA, the Texas Instruments Graphics Architecture software interface. In
terms of speed, there is not much to
choose between the 8514/ A and
MAY 1992
19
There are also some lower-cost
boards appearing which contain the
Sierra DAC (Digital-to-Analog Converter), which is 15-bit and generates
32,768 colours, and then there are
other 16-bit adapters such as IBM's
XGA which generate 65,536 colours.
For most purposes, a 256-colour
board based on the S3 chip would be
my choice, both in terms of speed and
economy.
What should you look for?
Hitachi's Model CM2187 is a 21-inch multi-sync colour monitor with a 0.31mm
dot pitch & a resolution ofup to 1600 x 1200 (non-interlaced). It is compatible
with a wide range of graphics standards & features microprocessor control.
TMS340x0, though the 8514/A-based
boards tend to be a little cheaper.
A new contender is the 86C911 chip
produced by S3 Inc. The boards based
on the S3 are particularly exciting,
not only because of their fast speed,
but because they cost about half the
price of the other two types.
Most graphics boards available gen-
erate 16 and/or 256 colours (4 and 8
bits per pixel), though there are other
more expensive boards available
which can generate 16.8 million colours (24 bits per pixel). These boards
would only entice the most demanding users who need photographic-like
images and can afford the thousands
of dollars required to purchase them.
16-inch Colour Display for the Mac
Apple's new Macintosh 16-inch Color Display
features 832 x 624 resolution & is supported by all
current Apple video cards & by the on-board video
interface of the Quadra CPUs. Alternatively, users
can choose the 8.24 GC card (not needed for
Quadras) which offers 32,768 colours & graphics
acceleration.
20
SILICON CHIP
Dot pitch is important - newer 17inch monitors are 0.26mm, while a
20-inch monitor should be 0.31mm
or less.
Autosizing is a definite requirement
if you will be changing modes and
may be either automatic or user-programmable.
Colour-correction may be important
depending on the type of work you
do. The new NEC FG series is one of
the few monitors available with this
feature built-in.
Non-interlacing at higher resolutions can increase viewer comfort but
it is important to match graphics card
capabilities to that of the monitor.
Finally, spend a reasonable amount
of time looking for the monitor you
need and don't skimp on price and
quality - you will spend long periods
looking at the screen.
SC
•Jim Sharples runs Computrack, a company that supplies PC-based desktop publishing equipment. Phone (02) 451 2521.
Only $129
Order Your Copy Today
00 RINGTODAYFOR.,A
•
FREE DEMO,Ol'SK
"Having 1st ACT! is like having your own personal, assistant
that thinks and works just like you."
.
Features pull-down menus and pop-up windows so you can
complete tasks with only a couple ofkeystrokes. Built in WordProcessor allows you to write to your contacts quickly and
easily. Time scheduler allows you to keep track of important
dates for calls, meetings and to-do's.
Keeps details of your contact.s at your' fingertips. Instantly
displays the entire contacts file - addresses, phone numbers,
notes you've written, as well as completed and future
activities, even personal details.
Do you have a computer? Have to keep track of more than
100 names and addresses? Then you need JstACT!.
Manages and Tracks your Contacts
Over 50,000 copies already sold in the USA
1st ACT! - The World's leading
contact Manager
Options: UB1 o case with front & rear panels . Front Panel
is punched and screened, rear is punched. $19.99 Approved Plug Pak $17.95
Kit $135.00
• Voice reco rding and reproducing LSI using an ADM algorithm.
• Capable of recording and reproducing up to a maximum of 16
phrases . • 4 different bit rates can be selected. (BK, 16K, 22K,
32K bps).• Pausing function . • Beep sound output.• Mute Circuit.
• Built-i n DRAM refresh circuit.• Built-in band pass filter. • Builtin microphone amplifier. • Built-in 10 bit DAC. • Built-in DAC
output buffer. • Uses a 640K resonator. • +5V single power. •
Clocked CMOS for low power consumption.• Variabledebouncing
time for start, stop and pause by the CPU terminal.
Features:
The CMOS chip used in this kit is a surlace mounteq device, and
so we have had these premounted to the board. The kit comes
complete with a full set of instructions and 1MB of RAM.
Prefitted CMOS Surface mount Chip
The CMOS LS I chip used for this project uses a minimum of
power. Reco rd ing and reproduction of the signals is processed
through the CMOS chip us ing an (ADM) Adaptive Dela Modulation
algorithm. This provides a clean clear recording.
An electret microphone is used, and the CMOS chip has a builtin microphone amplifier as well as a muting ci rcuit. A 57mm
speaker is provided to ensure quality reproduction. A 5mm LED
is included to show the unit is recording.
Low power consumption
This digital voice project has hundreds of uses and wil l only take
you a couple of hours to build. You can also install up to4M B of
RAM for longer recording ti mes. Power is supplied from a low
voltage plug pak (optional).
A Voice recorder you can build in a afternoon
Easy to build Digital
Voice Recorder
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Value packed kit
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you are able to build the Comma Fax/Modem
with a minimum of specialised skills. We have
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component is included. There is also a step-bystep guide to testing your Fax/Modem
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you are using the QL2 Software, then upgrade to the latest Version 2 for only $40.00 including P&P. This new
version has a number of new features. Call for a Fact Sheet.
Note: This device does not have an Austel permit in force. Connection to
Telecom lines is an offence.
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command seri es V compatible modem.
Features include V22/V22bis standards (V21/23
is an option) both 1200 and 2400 baud rates are
supported as yvell as auto answer, dialing and
disconnect. You will find it compatible with all
popular communication sen.rices including most
bulletin boards.
Now Available
$99.00
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MNP and V42bis option.
V21/23 option.
$39.00
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Build ~our Own Fax/Modem
This is a fully featured kit
The Comma Fax/Modem isa commercially designed kit you can build It
will turn your PC (or Macintosh) into both a fax machine which can
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transmit faxes up to 9600 baud, as well as a Modem which supports both
U).i 1200 and 2400 baud.
"C You get all the necessary components as well as a professional case, and
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power supply . You also receive FREE Fax/Modem software. All this for
less than $300.
The Comma Fax/Modem uses the latest technology in digital signal
processing to ensure lasting troublefree operation.
Send faxes from home
The Comma Fax/Modem is a fully featured fax machine similar to units
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costing over $1000, which will transmit faxes at up to 9600bp.
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faxes can now be sent directly from your PC without having to print
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them first. Programs supported such as Ventura Publisher, Wordperfect,
Q' Windows, TIF~' and Dr Halo to name but a few.
You can view incoming faxes on-screen or print them using a standard dot
matrix printer. Incoming files can also be exported in either TIFF or PCX
format
for use in most popular graphic packages.
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Only print the faxes you want to keep - just think of the savings on
expensive fax paper.
Time saving
The Comma Fax/Modem will also receive faxes in background while you
continue t o work.
When faxing out the Fax/Modem will redial an engaged number so you can
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be sure your faxes are sent. The software also automatically keeps a
complete log of both incoming and outgoing faxes.
Also supported are cover pages, broadcast faxes, and scheduling. The
software keeps a database type register ofregularly used fax numbers for
easy retrieval
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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.
Low cost
audio oscillator
This low cost oscillator is based on
the popular Wien bridge configuration. It is powered by a single +9V
supply and draws only 8mA, so it is
ideal for portable, battery-powered
operation. The frequency can be continuously varied over the range from
16Hz to 244kHz, with the output voltage variable from 10mV to 5V peakto-peak over this entire range.
There are four frequency ranges,
set by ganged switch Sla and Slb,
with the actual frequency being set by
the dual gang pot, VR1a and VR1b.
The two 4700 resistors in series with
VR1 prevent the resistance from becoming too low and stopping oscillation. These components are essential
to ensure that the upper frequency
limit is as high as possible.
VR2 is a presettable trimpot and
should be set for maximum output
voltage without clipping. You will
Bulletin board
watchdog
This circuit was devised to act as
a "watchdog" for a bulletin board
(BBS) and to reset the computer
should it "hang" for any reason. It
connects across the RS-232 line and
monitors DTR, TXD and CD (also
known as RLSD). An IDC ribbon cable is ideal for this application, as
an extra "D" connector is easily
added to the line. The inputs are
isolated by 100kQ resistors so that
line loading is negligible. The
1N914 diodes on the inputs prevent signal levels from going above
the +5V supply rail or below 0V.
IC1b forms an oscillator which
clocks a 4020 12-stage binary counter. Should the count reach a predetermined level without being reset, Q1 will be turned on, firing the
555 monostable which in turn op-
22
SILICON CHIP
VR1a
10k
VR1b
10k
470n
4700
S1b
S1a
0.1
0.1
o--1
.01
o-1
t--o
~
+9V
+9V
t--o
470lc
VR3
47k
♦
470k
.001
o--1
.001
470k
+9V
.01
4. 7
4.7+
+ .-
47k
VR2
47k
56011 OUTPUT
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D2 211N914
need to check the setting over each
frequency range to find the best compromise.
The output is fed via VR3 which
acts as a level control. before being
erates Q2 and relay RLY1 which
resets the computer.
Setting the 10kQ trimpot for a
clock frequency of 1Hz allows time
delays of up to 34 minutes to be
obtained, plenty long enough for
this application.
With the computer off-line, say
for maintenance purposes, the DTR
lead is low and gate IC1d will be
high, holding the counter chip reset. When on-line, DTR goes high
and pin 11 of IC1 falls low, allowing the counter to clock. Should
the computer transmit data, the TXD
lead will pulse high, to be inverted
by IC1c, and cause IC1d to reset the
counter. Thus, while on-line with
the computer sending data, the
watchdog circuit is continually being reset.
Should the computer hang, there
will be no activity on the TXD line
and when the counter reaches an
buffered via emitter follower Q1 which
provides a nominal source impedance
of 600Q.
Steven Merrifield,
Newlyn, Vic. ($25)
appropriate count, the computer
will be reset.
The CD/RLSD lead allows for the
counter to be paused whenever the
modem is communicating with another. This facility was not provided in the prototype but found to
be necessary, as the BBS which it
was monitoring did not send acknowledge characters when receiving large mail packets.
When waiting f9r a call, the BBS
regularly sends a reset string to the
modern, which serves to reset the
watchdog and thus prevents the
system from being unnecessarily
reset. This usually happens every
10-15 minutes, so a "watchdog
time" of 17 minutes (Q11 with 1Hz
clock) was chosen. The Q12 output
of the 4020 (pin 1) will give a watchdog time of 34 minutes.
Greig Sheridan,
Ashfield, NSW. ($30)
Airconditioning override
with kickdown switch
Most 4-cylinder cars with automatic
transmission lack power when accelerating or overtaking with the airconditioning on. This automatic cutout is
controlled by the switch under the
accelerator that controls the kickdown
solenoid.
The kickdown switch is used to
control a relay which is placed in
parallel with the existing kickdown
solenoid. The relay contacts are then
wired in series with the electromagnetic clutch on the airconditioning
Nicad fast
charger timer
+12V
These wires are connected to the "normally
ACCELERATOR
closed" contacts on the
KICK·OOWN
SWITCH
TOAIR
relay, so the airconCONDITIONER
--+--------CONTROL
ditioner runs normally
RELAYS
/,,/
during normal engine
KICK•OOWN
AIR CONDITIONER
demands, but when the
RLY1
SOLENOID
CLUTCH
I ELECTROMAGNETIC
transmission changes
down under acceleration, the compressor is
temporarily cut out. The
compressor. Most cars have some sort fan in the cabin continues to run, so
of connector harness to the clutch, so you should not notice that the comit should not be necessary to cut the pressor has cut out temporarily.
clutch wires - just put connectors on
Peter Bradstock,
the wires which run from the relay.
Epping, NSW. ($20)
11
10
+13.B V O - - - - - - - ~ - - - - - - - - - - - - + - - - - - - - - - - - + - - - - ,
16
This timer circuit is used in conjunction with a resistance lead for
fast charging 7.2V 1200mA.h nicad
racing packs from a 12V car battery. It normally takes 15 minutes
to charge a battery from flat but if
you then forget to disconnect it,
the battery will be damaged. Mechanical timers. can overcome this
problem but they can jam and the
result is still a ruined racing pack.
The circuit is simply a 555 timer
(ICl) which clocks a 4020 timer (IC2)
256 times over a period of about 15
01
8C337
10
IC1
555
RESISTANCE
LEAD
WI•
minutes. It then switches Ql and RLYl
off. VRl is adjusted to give the required period. The+ 13.8V supply rail
PACK
LED1'
.,.
i-
is derived from the car battery.
Paul Fitzgerald,
Te Aroha, NZ. ($20)
25-PIN D
CONNECTOR
CD/RLSD 8
i
4093
07
1N4002
270k
16
lO CLK
IC3
-555
VR1
10k
+5V
+
0+
TO
NICAD
IC2
4020
LED1
10:r
D3
1N914
-:-
,ol
'''
+
I
,+5V
RL1
71
IN PARALLEL
.,. WITH COMPUTER
RESET SWITCH
.,.
100kl
TXD 2
11
11
RESET
.,.
~
+5V
LED2
D5
1N914•
D8
1N4002
100k
OUT
DTR 20
FROM
PLUGPACK
06
1N914
+5V
1i
OV
~
T
GN077-
MAY1992
23
BY PAUL LYNCH
The PC game is changing again:
OS/2 is really here
PC users find themselves in an unusual position
in 1992: IBM is really after our dollars. The year
is still young but it is difficult to imagine that
much will happen that's more important than the
new release of the IBM operating system, OS/2.
IBM released version 2.0 of the system at the end of March. It's a true 32bit system, which means that it runs
extremely quickly.
MS-DOS and PC-DOS run at eight
bits in real mode - and Microsoft Windows at best runs in only 16 bits in
386-enhanced mode. As many users
have found, this higher mode of Windows is effectively no faster than the
usual protected mode.
OS/2 also tackles memory management in innovative ways that make
have a machine with a 40Mb hard
disc, it's quite likely that OS/2 is not
for you - at this time.
What we have now is software that
in effect will prescribe your hardware
configuration - if you choose to accept it. What IBM has done to encourage you to do this is really quite remarkable.
The nature of SILICON CHIP is pretty
obvious - it's a technical magazine.
But at some stage, the PC user looking
for software must recognise the corn-
"To run 05/2 version 2.0, you will need at least
an 80386SX central processing unit (CPU) chip.
You'll also need a lot of spare storage. The
minimum requirement is 15 megabytes"
previous systems quite obsolete.
All this is good - in fact, excellentnews. But part of the news is not quite
so good.
To run OS/2 version 2.0, you will
need at least an 80386SX central
processing unit (CPU) chip. You'll also
need a lot of spare storage. The minimum requirement is 15 megabytes. If
you install the lot, it will occupy 30Mb
of your hard disc. So if you already
24
SILICON CHIP
mercial environment in which he or
she is operating. There are many dead
ends in the history of the PC: I have a
number of software packages on my
shelves that I seldom used some years
ago and will never use again. They've
been a waste of money - quite a lot of
it, I'm sorry to say. They remind me
daily of the importance of looking
beyond the technical parameters when
buying major software and equipment.
The new version of OS/2 is quite
wonderful but a straight technical
statement of its characteristics will
not answer the sensible questions of
most users. After all, to run it, many
people must consider replacing their
present computer at a cost of some
thousands of dollars. Is this a good
idea? Answering the question calls
for a quick stroll through the marketplace.
The race for our dollar
Quite a lot of the stuff laid out in
the market is there not because it's
ready, but just to beat a competitor in
the race for our dollar.
Central Point Software and Symantec had just such a race last year Central Point was in a hurry to put PC
Tools 7.0 on the market, because
Symantec was in a hurry to present
Norton Utilities 6.0. Haste overcame
caution and within weeks of each
other, both manufacturers found it
appropriate to bring out free updates
designed to fix the errors that existed
in the products as first marketed. Central Point issued PC Tools 7.1 and
Symantec offered 6.01.
The feelings of people who purchased the bug-infested versions only
weeks or months earlier have not been
recorded publicly. But in a recent article in the American magazine PC
Computing, senior officials of WordPerfect were quite frank about the error they'd made in putting their version 5.0 on the market too soon a few
years ago. As they see it now, the
product had so many glitches that it
almost destroyed their reputation. (It's
worth recalling that it's only in the
past few months that WordPerfect re-
leased its Windows version - two
years behind its major competitors).
Beyond this urge to hit the market
at the earliest possible date, all software manufacturers find themselves
to a large extent in the fortune-telling
business. What do we users want?
What will we pay for? How much of
what we want should be in the final
package? WordStar users saw what
started out as a single double-density
disc program wind up, in version 5.5 ,
as one that needed 19 discs for the
same program with all kinds of bells
and whistles. I doubt that any single
user wanted, or applied, all the wonderful things offered on those 19 discs
but the manufacturer had a commercial need to supply the lot.
Since 1990, software manufacturers have had another question to answer: when they move beyond MSDOS, should they develop a Windows
version or an OS/2 version? OS/2 was
clearly a technically superior interface ·but market realities are such that
many of those software designers who
decided that OS/2 was the way to go
got their fingers burned quite badly.
While OS/2 had been round since
1987 as a joint effort between Microsoft and IBM, there was a rupture of
the partnership. Microsoft pulled out
because of the staggering success ,
starting in 1990, of its graphics interface, Windows.
The success of Windows
In any history of the PC, the appearance of Windows 3.0 will merit a new
chapter. Earlier versions of the program were glitch-ridden, and even 3.0
presented users with some difficulties, but largely due to the support of
other software manufacturers who
wrote programs to operate through
MS-DOS µlus the Windows 3.0 graphics interface, the Windows market
exploded.
Over nine million copies had been
sold by the end of 1991. This is why
Microsoft says "the market has spoken", suggesting that computer users
are so happy with their product that
they want, or will want, no other.
This is a doubtful proposition. But
the Windows success prompted
Microsoft to pull out of OS/2 development and concentrate on later versions tlf Windows. Version 3.1 came
out last month and Windows NT - a
32-bit package - is promised for late
this year. Presumably, NT will be the
first true Windows operating system,
as distinct from an add-on to the basic
MS-DOS: which is what versions 3.0
and 3.1 are.
Microsoft says that no matter which
version you buy, it will always look
like what you're used to. The present
Windows interface will always be retained - as far into the future as its
technical people can see.
So why should users buy OS/2 version 2.0 instead of sticking with Windows? There are a few reasons. The
first and most dramatic is probably
that OS/2 actually includes Windows
3.0 and IBM promises that it will continue to enhance its Windows versions in the package - to match 3.1
and, later, to match NT.
How is this possible? It's because
IBM and Microsoft signed a development deal for graphic interfaces back
in the eighties that gave IBM full rights
to all programming codes developed
during the course of that agreement.
This agreement runs as far as the coming Windows NT, IBM claims, and
includes it.
So if you like Windows, and want
to use it, you now have a choice of
buying the Microsoft version or the
IBM version. If you buy Microsoft,
you will also need to buy MS-DOS,
on which Microsoft Windows stands.
If you buy OS/2 version 2.0, you will
find it includes DOS - and goes beyond it into 32-bit processing.
Countless forests have been hewn
to bring computer users the first reports on what OS/2 is, and what it
does. Here is a simple Q&A that answers some questions about whether
it belongs in your computer - now, or
in the future.
What's the minimum hardware
I'll need for OS/2?
IBM says this is an 80386SX with
60Mb of storage and 4Mb of RAM. A
smaller hard disc may suffice if you
are running compression-on-the-flysuch as Sup erStor, Stacker or
DoubleDisk. Obviously, the faster your
CPU chip , the greater your RAM and
the larger your hard disc, the better
OS/2 will run.
How much disc space
will I need?
The bare-bones installation occupies 15Mb and there are alternative
installations that take you up to 30Mb.
The higher-end installations, however,
STOCK
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FANS
80 x 80 x 25mm 240VAC .... $16.84
120 x 120 x 38mm 240VAC $16.92
Fan Finger Guards for
80mm Fans ....... ........ .. .. .... $1.43
Fan Finger Guards for
120mm Fans ........... .... .. .... $2.12
MISCELLANEOUS
Circuit Breakers 7.5A- Press
To Reset .. .... .......... .. ... .... ... $7.25
Mains Power Lead 10A
1.8m long ...... .... ... .......... .... $4.16
9V Battery Snaps .... .. ..... ....... $0.20
2 x AA Battery Holder ... ...... .. . $0.28
12-Way terminal block 10A .. . $1.60
SEMICONDUCTORS
1N4004 Diodes ... ... ......... ...... $0.07
1N4007 Diodes .. ..... .. ... ... .. ... . $0.1 0
1N4148 Diodes ................ ... .. $0.04
MJ15003 Transistor ........ .. .... $6.50
MJ15004 Transistor ........ ... ... $6.50
MJ15024 Transistor ..... ......... $8.60
MJ15025 Transistor ..... .... ... .. $8.60
MJ13007 Transistor ....... .. .. ... $4.87
MFR571 Transistor ..... .......... $4.27
NE555 IC ... .. .... ... ............ .. .. .. $0.30
TL494 IC .... ... .... ...... ... ........... $2.83
MC14514 IC ..... ....... .... ..... ..... $3.00
MC34063 IC ....................... ... $2.98
ALL ITEMS 10 PLUS 10% OFF
HY CAL ELECTRONICS
Unit 4, 62 Gt. Western Hwy,
Parramatta, NSW 2150.
Phone (02) 633 5477
Fax (02) 891 5640
Credit Cards Welcome
MAY 1992
25
are those including the on-line help,
and if you don't have this, your learning curve may be a longer one.
There's a type-font program. (These
are just the things I found in my review copy. I'm told there's more).
How much does it cost?
Are any OS/2 application
packages in the market?
Beats me. The recommended retail
price is $275 but you could get it for
about $250 on the day it hit the shops.
IBM is apparently interested in discounting to get a leg into this market
which ultimately can bring them hundreds of millions of dollars.
How well does it work?
Brilliantly. An IBM publicist said
last year that the new package would
"run DOS better than DOS and Windows better than Windows". OS/2
certainly does that, for two reasons.
One is that it's a 32-bit package - your
DOS and Windows applications run
faster. The other is that IBM, just like
Microsoft, has had about two years to
clean up some of the things that trou-
Yes. In June last year, you could
buy PageMaker, CASE, Carel Draw,
Lotus 1-2-3, PackRat, Ventura, WordPerfect and other packages in OS/2
versions. Microsoft was offering Excel and Word. IBM spread its programming codes around for version
2.0, and now claims that 800 applications are now available or in advanced
preparation. Note, by the way, that
the programs listed here sold for the
same prices as the Windows versions
in almost every case.
Is OS/2 here for the long haul?
We don't know whether any of the
current systems are here for the long
haul. How long a haul are we think-
"OS/2 actually includes Windows 3.0 and IBM
promises that it will continue to enhance its
Windows versions in the package - to match
3.1 and, later, to match Windows NT"
bled Windows users with the 3.0 package. I couldn't get any Unrecoverable
Application Errors from my OS/2 Windows, for example. Memory management is wonderful.
I don't use Windows and don't want
to. What's in OS/2 for me? Quite a lot
of things. Your DOS programs will
run faster. RAM cram vanishes because of the way OS/2 presents DOSwhich is that it sets up a new DOS
simulation for every DOS program you
get into. These simulations each have
something like 630Kb of available
RAM. Task switching is better. The
REXX programming language supplied is better. And besides, OS/2 is
bundled with a lot of things beyond
the operating system itself.
And these are?
There's a database and a spreadsheet. There's a good communications
program for modem users. There's a
calendar/diary/personal information
manager. There are excellent games.
There's a 5-disc suite of device drivers, including scads of mouse drivers.
26
SILICON CHIP
ing of? It's pretty obvious that OS/2,
DOS and Windows are here for as
long as we're using x86 Intel CPUs.
And IBM has already worked out how
to transfer our OS/2 data files to RISC
processors. Only a brave or foolhardy
person would predict what CPUs we'll
be using 10 years from now.
How confident can I be that
OS/2 works?
Pretty confident. IBM issued 30,000
beta copies before release and licensed
many of the beta assessors to make up
to 10 copies of the beta code. When
Microsoft released MS-DOS 5.0 last
year, it announced there had been
5000 beta testers - at that time, the
largest such program in history. DOS
5.0 doesn't seem to have too many
dark and spooky corners.
Do I really need OS/2?
It's up to you. If you often sit in
front of your computer waiting for it
to do things, for example, you'll spend
less such time with OS/2. If you're
crashing your present system often,
you should enjoy less crashes under
OS/2, because of the improved memory management.
If you foresee working with any
software that calls for a lot of calculation, you can rest assured that somebody out there is writing or bringing
to market a 32-bit version that won't
run under DOS. If you're already running a program you want to be faster,
check with your program's Australian agent when the OS/2 version will
be available. Your DOS or Windows
software will be faster within OS/2;
your OS/2 application will be faster
again: in some cases, much faster.
What are the disadvantages?
The main one, is that you have to
learn it. It's not much fun learning
any new software. One of the many
charms of Microsoft Windows is that
its Program Manager interface slashes
the learning time for new applications; but you have to learn the PM
interface before you can take advantage of this. In exactly the same way,
you have to learn how OS/2 works.
The other disadvantage is the high
hardware requirement. You may not
be able to run OS/2 at all on your
present computer. Then again, you
may not be able to run Windows NT,
either.
·
How do you see OS/2?
My view is that it shows us where
the PC is going. Not everybody has to
follow this path. If you want a simple
business machine for word processing, plus a couple of simple DOS and
Windows programs, you can continue
happily with an 80286 machine, a
couple of megs of RAM, and a 2040Mb hard disc. These machines are
really cheap today and will get
cheaper in the future.
OS/2's ability to run DOS and Windows now, and keep up with Windows even through the NT evolution,
is a powerful incentive to adopt the
system. And the higher-level machines are also getting cheaper.
Coincidentally, just as I was finishing this column, I saw a newspaper
advertisement from a well-known
clone supplier. It was for an 80486-40
machine with 64Kb RAM cache,
125Mb hard disc and 4Mb RAM- for
under $2200. Two years ago, an 80286
with a 40M hard disc, no cache and
2Mb of RAM, could cost you $5000 or
more.
SC
All this month you'll find fantastic new products and sensational value
at Dick Smith Electronics! Hurry in today for the latest in kits, books,
tools and shortwave rad ios.
Bffi~~~~,?-
Exceptional performance and specifications make the
Playmaster series a popular choice among kit builders.
This classic 30/30W stereo amp is no exception; it's
superbly engineered and designed to enhance the
output of any music system. All components (including
heatsinks) are mounted on one PCB so it's easy to
build. It comes complete as a full form kit with PCB,
hardware, pre-punched rack-mounted case, prepunched silk screened front panel and all components.
t~•i=Jifi~-~:! ~;fJi
A great idea when there's one VCR and two televisions.
Now you can play a video and watch it from another
television without connection leads from VCR to TV. All
components for UHF or VHF modulator output are
included . What's more, it's simple to construct and
comes as a full form kit with PCB, all components and
front panel label. You'll have to build your own
antenna, so PCB's and instructions are also included.
Cat K-5700
Cat K-5600
QQ
ti i: ift{~l•t◄ ;j 1113~ l·IB i•'-' t•J ;j
A high performance yet inexpensive benchtop audio
oscillator. It covers the frequency range from around
6Hz to ?0kHz in four ranges with very low distortion.
What's more, in terms of practical and general use,
this oscillator really delivers. It comes as a full form kit
with all components, PCB, case and pre-punched silk
screened front panel.
Cat K-7340
Mf~1filiilll
Active crossovers are an effective way to improve
loudspeaker performance. This inexpensive crossover
kit includes features found only in systems costing
thousands of dollars. To overcome the limitations of
passive crossovers the active crossover filter network
is shifted so that it precedes the power amplifier. The
advantages of this system include; ideal high
impedance loads, less discrepancies in speaker driver
efficiency and less resistance between the voice coil
and amplifier. Short form kit complete with PCB and
all components.
Cat K-5405
$5995
1:1•)·Milt(•)~il!1ii11;j
A low cost multimeter packed with
features! It's compact, reliable and
great fun to build. With continuity
testing, a wide 10A DC range and
battery checker. It has 19 ranges
plus dB, 20K/V sensitivity, diode
and fuse protection. Complete with
all components , printed circuit
board, quality case, probes and full
instruction manual. Ideal for the
hobbyist or professional.
Cat K-1040
QQ
Q
t-v ;I I 3•l!l•J ~ i~Ii 13 :j
A simple voltmeter that can save you money. It gives a
visual indication of the charging system of a 12V
battery. The three LED's show if battery voltage is low,
correct or high . This way, you can tell if voltage is
dropping or if your battery is overcharging . It's super
easy to build , includes a small PCB which fits the a
35mm film contain_
er, or your pocket.
Cat K-4205
$695
N!W
Q
B1316
With Cassette Player
Listen to the world, local AM/FM stations or your
favourite cassettes with this professional dual
conversion, all-band world receiver. The Sangean
ATS-81 BCS covers AM/FM bands, FM stereo (with
optional earphones), Longwave and Shortwave
bands. Top of the line features include a 45 station
memory, large digital display, BFO control, keypad
frequency entry and much morel
FEAlURES
• Covers AM/FM, Longwave (150 to 519kHz) and
Shortwave (1.62 to 29.99MHz) bands
• Five tuning methods, including keypad frequency
entry and rotary dial tuning
• 45 station memory
• Easy to use keyboard controls
• Dual time display for local and UTC
• AM wide/narrow I.F. filters
• Pushbutton selection of major SW bands from 120m
to 11m
• Standby functions for radio, buzzer or recording
functions
• Adjustable RF gain prevents overloading from very
strong signals
• BFO (Beat Frequency Oscillator) control for receiving SSB and Morse code
transmissions
• Dual conversion design for improved receiver performance
• Large LCD screen with frequency, time, station preset channel, signal, battery
strength and icons.
• Pushbutton cassette recorder with Cro2 facility and auto- stop
CalD-2842
2 Tools In One!
If you thought only Superman
had X-ray vision ... think again!
The tracker detects wood,
metal and live cables
through walls, floors, plaster
board, chipboard and
panelling, etc. It's ideal for
locating joints, battens and
rafters through walls when
Installing pictures, shelves or
ceiling fans. As well, you can
use it to detect live/dead
cables, pipes and mains, etc.
A safe and easy alternative to
'blind drilling'. Requires 9V
battery.
CatT-1990
$399
Rechargeable
Get the features, design and
specifications of a professional unit
at an affordable price. This
incredibly easy to use 10Hz to
1.2GHz frequency counter has an 8digit LED display and 3 switchable
gate times. It comes with a
rechargeable battery and a DC
power socket, so you can work and
recharge it at the same time.
What's more, it recharges in 5 hours
and has overcharge protection. It's
ideal for measuring radio
frequency transmissions as well as
servicing stereos, videos, computers
and cordless phones. With Hi and
Low BNC connectors and
calibration adjustment. Includes a
full 12 month warranty.
Cal Q-1320
Specifications
Frequency Range
Impedance
Max. Voltage
Range B
Range A
10Hz- 20MHz
20MHz - 1200MHz
1 MEG Ohm,80pf SO Ohm
100Vp-p
5Vp-p
Gate Time: 2s, 0.02s, 0.002s Switch
Selectable
Read Out: KHz or MHz
Power:
8.4V rechargeable
battery or optional
12V/500mAadaptor, Cat
M-9627
B1316
WIRE AND CABLE ·FOR
ELECTRONICS .•. . .
Nell Sclater
The most comprehensive source of
information available on topics
including the properties of conductors,
insulation system design and
assembly techniques. What's more, it
has guidelines for the latest wire and
cable equipment. With international
code designations, plus wire and
cable specifications for the most
simple, through to the most advanced
applications.
Cat B-1618
Learn from the experts. Tips and winning secrets on how to
play the hottest video games around. With storylines, hints
and full colour screen shots. It even has game
evaluations, so you can read about a game before you
buy it.
NINTENDO GAMES PLAYER'S
ENCVCLOPEDIA VOL 1-3
B-9900/B-9901 /B-9902
$4995
NINTENDO GAME PLAYER'S
ENCYCLOPEDIA VOLUME 4
Cat B-9903
Peter Norton & Robert Jourdain
~195
An easy to read book designed for
IBM PC users at all levels. PC
Problem Solver extends beyond
DOS to cover Networks,
Communications, Windows 3.0 and
DOS 4.0 DOSSHELL programs. With
many time-saving tips on utility
software and trouble-shooting, from
the man who invented Norton
Utilities!
IBM PC GAMES PLAYER'S
ENCYCLOPEDIA'S VOLUME 1-2
Cat B-6800/B-6802
$4995
Cat B-6200
QUE QUICK REFERENCE POCKET
BOOK GUIDES
Essential and inexpensive! The QUE
range of computer guide books
are the smart and easy way to
solve problems and find specific
commands quickly. Though not
intended to replace complex user
manuals, they cover all the
essential information you'll need to
get started.
li~M-18
r en 11 spaugh
A practical insight for children,
students or adults interested in
aviation and space flight. Dr
Millspaugh received the 1989
'Aerospace Teacher of the Year
Award' and the 'Award for
Excellence in Aerospace
Education'. This book contains the
very best of experiments devised
and presented by his own students.
Includes principles of buoyancy,
propulsion, atmospheric
composition, Newton's laws and
more!
$1695
Cat B-6702
TITLES INCLUDE:
Cat No.
Wordperfect 5.1
Microsoft Word 5
MS-DOS 5
Norton Utilities
Fastback
Hard Disk (DOS 4.01)
PC Tools
Lotus 1-2-3(Release 3.1)
B-6400
B-6402
B-6404
B-6406
B-6410
B-6412
B-6414
B-6408
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STORES ACROSS AUSTRALIA AND NEW ZEALAND
B1316/LB
A low-cost
electronic doorbell
Has your doorbell broken down? This
unit uses readily available parts to
produce a realistic & pleasant "dingggdonggg" sound.
By DARREN YATES
These days, like most consumer
goods, doorbells are treated as a
"throw-away" item - the cost of repairing one invariably exceeds the cost
of buying a new one. If your doorbell
has broken down or if you don't already have one, then here's an ideal
opportunity to build a deluxe unit for
yourself.
As you can see from the photographs, we built two versions, one
housed in a commercial doorbell case
(from Dick Smith Electronics) and the
other in a plastic zippy box. Apart
from that, the two units are identical.
Go for the Dick Smith Electronics version if the unit is to be seen as well as
heard.
In other situations, the zippy box
version may be the more convenient,
particularly if the unit is to be hidden
from view on top of a cupboard or a
bookcase.
The last time that we used a 2-tone
chime circuit was in the Door Minder
project, published in February 1988.
That circuit used an SAB0602 2-tone
chime IC which has subsequently become hard to get and expensive.
This project overcomes that problem by using common CMOS ICs. In
fact, parts of the circuitry are similar
to the Executive Thingie project in
last month's issue.
When the front doorbell switch is
pressed, this project generates the
familiar "dinggg-donggg" sound by
sequentially feeding the outputs from
two tone generators to a small power
amplifier. These tone generator outputs are fed to the amplifier via separate CMOS FETs which act as variable
resistors to give the required decay
characteristics.
Power is derived from a 6V battery
pack consisting of four 1.5V AA cells.
If you use alkaline types, they should
last for about one year or so. Alternatively, you could replace the batteries
with a 6V 300mA plugpack and forget
about them.
Block diagram
Refer now to Fig.1 which shows the
block diagram of the Doorbell. We'll
Left: this view shows the completed
electronic doorbell in the commercial
case that's available from Dick Smith
Electronics. This case has a dark
brown front panel with metallic
highlights and this attaches by four
screws to a cream-coloured midsection. The rear-panel, which is
moulded in black plastic, is secured
to the wall and the front assembly
then clips over it.
30
SILICON CHIP
Ii
BELL
PUSH
DEBOUNCE
HALF
MONOSTABLE
HALF
MONOSTABLE
IC1a
IC1b
IC1c
D1 D2
VOLTAGE
CONTROLLED
RESISTOR
IC2a
AMPLIFIER
BIAS
CONTROLLER
VOLTAGE
CONTROLLED
RESISTOR
IC2b
[(J SPEAKER
HIGH TONE
OSCILLATOR
LOW TONE
OSCILLATOR
IC1d
IC1e
AMPLIFIER
03-06
Fig.1: when the doorbell switch is pressed, the two half monostable stages
(IC1b & IC1c) are activated in sequence & apply bias to voltage controlled
resistor stages IC2a & IC2b. These stages then modulate the outputs from the
tone generators (IC1d & IC1e) & the resulting signals are then fed to an audio
amplifier stage (Q3-Q6).
due to switch contact bounce or due
to spikes generated in the switch leads
by nearby lightning strikes or mains
transients.
From there, the output is then fed
into two half-monostables based on
IClb and IClc. These provide the correct time delay between the two tones
of the doorbell.
Each half-monostable is connected
to a voltage-controlled resistor network (IC2a & IC2b) and these modulate the outputs from tone oscillator
stages ICld & ICle to give the characteristic ringing sound. The outputs
from the voltage controlled resistor
stages are then fed to the audio ampli-
just go through it briefly at this stage,
so that you will understand the basics
of the circuit.
The front doorbell switch is connected to a debounce circuit based on
ICla. This prevents false triggering
Fig.2 (below): the final circuit uses the
FETs from a 4007 IC as the voltage
controlled resistors. When S1 is
pressed, Ql turns on & provides bias
to IC2a which allows through signals
from oscillator stage IC1d. Ql then
turns off & Q2 turns on to provide bias
for IC2b which then passes signals
from tone oscillator IC1e.
100
+
16VWJ
T
6V
1
+
Circuit diagram
Let's look now at Fig.2 which shows
the complete circuit details. The
project is based on two common CMOS
ICs and six transistors.
Let's start again with the doorbell
*
150k
I
...I...
fier stage (Q3-Q6) and to the loudspeaker.
We've pulled rather a neat trick with
the audio amplifier stage, however.
Because the circuit is powered continuously, we have to make the quiescent current (ie, the current flow when
the circuit is in its idle state) as low as
possible, to conserve the batteries.
By using CMOS ICs in the front
end, we have no problems here but
we have to control the quiescent current of the audio amplifier. The easiest way to achieve this is to use the
half-monostable outputs to control the
DC bias of the amplifier via an OR gate
(Dl & DZ).
When the circuit is in its idle state,
the monostable outputs are low and
no forward bias is applied to the amplifier. Thus, the quiescent current
drawn by the audio amplifier is reduced to zero. Conversely, when either half monostable output is high,
the output of the OR gate is also high
and bias is applied to the amplifier
which then operates as normal.
This allows us to keep the quiescent current down to only 160µA. Not
bad,huh?
2.2M
+6V
01I
t14
IC2b
1
OOOR I
BELL
S1
10
3.3M
.,.
8.2k
2.2 +
25VW+
t9
-¥-
12
-:-
+6V
*
120k
+6V
01 +
10k
02
1N914
IC2a
4007
03
BC54&
8.
eLJc
2.2 +
25VW+
VIEWED FROM
BELOW
10k
.,.
*SEE TEXT
DOORCHIME
MAY 1992
31
Fig.3: you can install
the parts on the PC
board in any order but
take care with the
orientation &
placement of the
transistors & ICs. The
two resistors marked
with asterisks may
need adjusting to get
the correct tones.
switch. The 2.2MO resistor, the 0.lµF
capacitor and Schmitt trigger stage
ICla form the de bounce circuit. These
components clean up the waveform
produced by the bouncing switch contacts to give a positive-going pulse on
pin 2 of ICla each time the switch is
pressed.
This positive-going pulse is then
AC-coupled to the first of the halfmonostable stages. This stage consists
of IClb and its associated 0. lµF capacitor and 4.7MO resistor.
Normally, pin 5 ofIClb is held low
by the 4.7MO resistor and so its output at pin 6 is high and transistor Ql
is off. When pin 2 of ICla switches
high (ie, when the doorbell is pressed),
IClb is immediately triggered and
switches its pin 6 output low. Pin 6 of
IClb then switches high again a short
time later on the trailing edge of the
input pulse, as set by the RC time
constant on pin 5.
When pin 6 ofIClb goes high again,
the second monostable based on IClc
is triggered into action. This halfmonostable works in exactly the same
manner as the first and switches its
pin 8 output low for a brief period.
Thus, the two half-monostables
work in a sequential fashion, with
IClb first briefly switching its output
low and then IClc doing the same.
Voltage-controlled FETs
Transistors Ql and Q2 buffer these
outputs and in turn drive the voltage
controlled resistor stages IC2a and
IC2b. These stages are actually the ~channel FETs from two complementary pairs inside a 4007 CMOS IC.
When pin 6 of IClb switches low,
Ql turns on and quickly charges the
2.2µF capacitor on its collector. This
turns on N-channel FET IC2a by pulling its gate (pin 3) high, so that it now
passes signal from tone oscillator stage
ICld.
When pin 6 of IClb switches high
again, Ql turns off and the 2.2µF capacitor discharges via its parallel
680kO resistor. This sets the decay
time for the tone oscillator signal. As
the voltage across the 2.2µF capacitor
decreases, the source-drain resistance
of the FET increases so that the signal
level on pin 5 decays to zero.
Q2, IC2b & ICle operate in exactly
the same fashion. When Ql turns off,
Q2 immediately turns on and this
turns on IC2b which now passes signal from tone oscillator ICle.
The two tone oscillators (ICld &
ICle) are standard Schmitt trigger configurations with RC feedback components. ICld is the high tone oscillator
and ICle is the low tone oscillator. Or,
to put it another way, Ql, ICld and
IC2a produce the "ding", while QZ,
ICle and IC2b produce the "dong".
Output amplifier
The tone outputs from the FETs are
mixed via two 10kO resistors and coupled to the base of Q3 in the audio
amplifier via a 0.22µF capacitor. A
.033µF capacitor then filters the waveform on Q3's base to give it a more
"mellow" sound.
The audio amplifier is a fairly standard 4-transistor class B arrangement
but note that no fixed bias is applied
CAPACITOR CODES (10%)
0
0
0
0
0
Value
IEC Code
EIA Code
0.22µF
0.1µF
.033µF
.01µF
220n
100n
33n
10n
224K
104K
333K
103K
RESISTOR COLOUR CODES
0
0
0
0
0
0
0
0
0
0
0
0
0
32
No.
Value
4-Band Code (1%)
5-Band Code (1%)
1
4.7MO
3.3MO
2.2MO
680k0
330k0
220k0
150k0
120k0
10kO
8.2k0
6.8k0
1.5kO
yellow violet green gold
orange orange green gold
red red green gold
blue grey yellow brown
orange orange yellow brown
red red yellow brown
brown green yellow brown
brown red yellow brown
brown black orange brown
grey red red brown
blue grey red brown
brown green red brown
not applicable
not applicable
not applicable
blue grey black orange brown
orange orange black orange brown
red red black orange brown
brown green black orange brown
brown red black orange brown
brown black black red brown
grey red black brown brown
blue grey black brown brown
brown green black brown brown
2
1
1
1
4
2
1
2
SILICON CHIP
The PC board is secured to the rear panel of the DSE case on 25mm tapped
standoffs. Note that the lOOµF capacitor at top right is mounted with its body
flat against the PC hoard so that it clears the loudspeaker.
to Q3 or to the complementary output
pair (Q5 & Q6). Q3 is wired as a common emitter amplifier and provides
most of the voltage gain. Its collector
output drives Q4 which in turn functions as a driver stage for Q5 and Q6.
Note that the bottom end of Q6's
1.5kQ base bias resistor has been connected to the output rather than to
ground. Because Q5 and Q6 together
function as an emitter follower with a
voltage gain of almost unity, there is
almost no AC voltage across the 1.5kQ
resistor. This means that very little
signal current flows in the resistor
and thus its impedance does not load
the output of the preceding stage, Q3.
This technique is called "bootstrapping" and it results in greater signal
output.
The gain of the amplifier is set to
approximately 4.5 by the ratio of the
6.8kQ and 1.5kQ feedback resistors.
The amplified audio signal appears at
the emitters of Q5 and Q6 and is coupled to the loudspeaker via a 100µF
capacitor.
Bias control
The DC bias control circuit for the
amplifier is quite simple but very effective in reducing the quiescent current to zero under no-signal conditions. As mentioned earlier, it is based
This view shows how the batteries are hidden in one
channel of the DSE case. The front & mid-sections of the
case are held together by four self-tapping screws.
on diode OR gate Dl and DZ.
This OR gate drives a voltage divider consisting of ZZ0kQ and 330kQ
resistors. The voltage developed at
the junction of this voltage divider
then provides the DC bias for the audio amplifier. Let's see how it works.
When Sl is pressed, Ql immediately turns on as described previously
and pulls Dl 's anode high. Thus, the
output of the diode OR gate also goes
high and this applies approximately
3.ZV of DC bias to the base of Q3 via
the voltage divider.
Similarly, when Ql turns off and
QZ turns on, the output of the OR gate
is pulled high via DZ and base bias is
applied to Q3 as before.
When the output of the OR gate
subsequently goes low (ie, at the end
of the two tones), the lOµF capacitor
immediately begins discharging via
the ZZ0kQ and 330kQ resistors. This
progressively removes the DC bias
from Q3 over a 5-second period, thus
effectively shutting the amplifier
down until the button is pressed again.
By the way, if the doorbell switch is
pressed and held down, the Doorchime will only operate once and then
stop. That's because IClb can only be
triggered when pin Z ofICla switches
from low to high (ie, the change of
state is necessary to trigger IClb).
Thus, to get the Doorchime to sound
repeatedly, it is necessary to repeatedly press the doorbell switch.
Board assembly
Fig.3 shows the parts layout on the
PC board. This board is coded SC031069Z 1 and measures 108 x 74mm.
Before starting the assembly, check
The four plastic ribs on the back of the front section must
be snapped off before the final assembly, to provide
clearance for the PC board.
MAY 1992
33
Now for the big test. Connect the
loudspeaker, bell push (S1) and battery connector to the PC board, then
snap the battery into position. If
everything is OK, the circuit should
trigger immediately power is applied.
After that, you will have to press S1
to trigger the unit - disconnecting
and reconnecting the battery will not
do the job unless you discharge the
lO0µF filter capacitor across the supply.
Adjusting the tones
A plastic zippy case can be used to house the PC board if the unit is to be
hidden out of sight (eg, on top of a cupboard or bookshelf).
the board carefully by comparing it
with the published pattern. If you find
any defects, correct them immediately,
then install the four wire links. Make
sure that the links are straight, so that
they don't short against other parts.
Once the links are in, you can install the resistors, diodes and capacitors. The two resistors marked with
asterisks should be soldered to PC
stakes and not directly to the board
itself. This makes it easy to make adjustments to the tone oscillators, as
we'll explain later.
The accompanying table shows the
resistor colour codes but it's also a
good idea to check them on your multimeter before installing them on the
PC board. Make sure that the diodes
and electrolytic capacitors are correctly oriented.
Finally, you can complete the board
assembly by soldering in the ICs and
the transistors. Be sure to use the correct transistor type at each location,
as both NPN and PNP types are used
in the circuit. Fig.2 shows the pin
connection details for the transistors.
Install a plug and
socket in series
with the battery
leads if you are
using the DSE case,
so that you can
easily separate the
front section from
the rear panel
assembly. This will
make it much
easier to replace
the batteries when
they eventually go
flat.
34
SILICON CHIP
At this stage, the tones might sound
a bit ''wonky" but that's easily fixed
by changing the values of the feedback resistors in the tone oscillators
(ie, those marked with asterisks). You
simply increase the resistor values for
lower tone frequencies and decrease
them for higher frequencies.
For example, to lower the frequency
of the "dinggg", increase the value of
the 12okn feedback resistor in the
high tone oscillator.
If you're the cautious type, then
connect your multimeter (set to the
mA range) in series with one of the
battery leads before initially applying
power. It should indicate a peak current of about 40mA as the doorbell
sounds, but this should then rapidly
fall away to about 160-170µA after 10
seconds or so.
If you get any readings other than
these, (eg, if you get a current of 40mA
or more continuously), switch off immediately and check for wiring errors. In particular, check for incorrectly oriented parts and for shorts on
the copper side of the board (eg, shorts
between adjacent IC pads).
Final assembly
Once the circuit is working correctly, you can install it inside the
case. If you're using a plastic zippy
case, first attach the adhesive label to
the front panel and drill out a pattern
of 5mm-diameter holes to let the
sound escape from the loudspeaker
(note: drill small pilot holes first).
The loudspeaker can then either be
glued•in position or secured to the lid
using two small aluminium brackets,
machine screws and nuts (see photo).
The PC board is mounted on the
bottom of the case at one end, so that
it sits underneath the loudspeaker.
Check that there is enough room at
the other end of the case for the batteries before drilling the mounting holes.
91
n
(/)
C)
w
~
C)
(J'I
"°nJ
Fig.4: this is the full-size etching pattern for the PC board (code SC03106921).
The board can then be mounted in
position on 5mm spacers and secured
using screws, nuts and star washers.
The assembly can now be completed by drilling a small exit hole in
the side of the case for the leads to the
doorbell switch . .These leads can be
made as long as is necessary to connect the unit and doorbell switch together.
The alternative Dick Smith Electronics case is a 3-piece assembly of
moulded plastic. The front piece is
dark brown with m etallic highlights
and this attaches by fo ur screws to a
cream-coloured mid-section. The rearpanel, which is moulded in black plastic , is secured to the wall and the
front assembly then clips over it.
If you're using the Dick Smith Electronics case, it's simply a matter of
gluing the loudspeaker into the mould
on the rear panel and mounting the
PC board over it on 25mm-long plastic standoffs. These standoffs are
mounted on either side of the loudspeaker and the m ou lded battery
holder (see photo).
Don't forget to connect the loudspeaker leads before mounting the PC
board with its co de number adjacent
to the loudspeaker.
Battery arrangement
The zippy box version has a series of
5mm-diameter holes drilled in the
front panel to allow sound to escape
from the loudspeaker.
The battery holder moulded into
the rear panel is not used here. Instead, the batteries are clipped into a
separate long holder which is cleverly hidden in one of the channels
that run down both sides of the case.
You gain access to these channels by
undoing the four screws that hold the
front and middle sections together.
The battery holder is installed in the
righthand channel, as viewed from
the back, and the leads passed out
through the cutout in the centre of the
channel.
By the way, it is a good idea to
install a plug and socket in series
with the battery leads so that you can
easily separate the section containing
the batteries from the rear panel as-
PARTS LIST
1 PC board, code SC03106921,
108 x 74mm
1 plastic zippy case, 150 x 90 x
50mm; or 1 commercial
doorbell case from Dick Smith
Electronics (see note 1)
4 1.5V AA cells (alkaline)
1 4 x AA battery holder (square
for zippy case, long for DSE
case)
· 1 75mm 8-ohm loudspeaker
1 front doorbell switch (DSE Cat.
P7554; Jaycar Cat. SP-0780)
4 5mm spacers (25mm for DSE
case)
Semiconductors
1 74C14 hex Schmitt trigger
inverter (IC1)
1 4007 complementary pair plus
inverter (IC2)
3 BC558 transistors (01 ,02,04)
1 BC548 transistor (03)
1 BC337 transistor (05)
1 BC327 transistor (06)
2 1N914 signal diodes (D1 ,D2)
Capacitors
2 100µF 16VW RB electrolytics
1 10µF 16VW RB electrolytic
2 2.2µF 25VW RB electrolytics
1 0.22µF 63VW MKT
4 0.1µF 63VW MKT
1 .033µF 63VW MKT
2 .01 µF 63VW MKT
Resistors (0.5W,
1 4.?MQ 5%
1 3.3MQ 5%
1 2.2MQ 5%
2 680kQ
1 330kQ
1 220kQ
1%)
1 150kQ
1 120kQ
4 10kn
2 8.2kQ
1 6.8kQ
2 1.5kQ
Miscellaneous
Tinned copper wire; insulated
hook-up wire; figure-8 bell cable;
machine screws, nuts & washers.
Note 1 : the Dick Smith Electronics
doorbell case is available only as
part of a complete kit.
sembly. This will make it much easier
to replace the batteries when they
eventually go flat.
Finally, it is necessary to remove
four plastic ribs from inside the case
before clipping it over the rear panel
assembly. These ribs can be easily
snapped off by hand.
SC
MAY 1992
35
Don't spend big
bucks on batteries
for your Sony
Walkman ®. This
simple voltage
regulator will let
you power it from
a plugpack supply
or from your car's
cigarette lighter
socket.
The
If you like listening to your personal
player in the car or while relaxing in
your favourite chair, then this project
is a must. It's a very simple voltage
regulator circuit that's designed to
conserve the player's batteries for those
times when you want to listen "on the
move".
We've christened the project The
Eliminator because that's just what it
does - when it's plugged in, it effectively eliminates (or bypasses) the player's internal battery. In use, The Eliminator is simply connected between a
plugpack supply (or car battery) and
the player's DC socket. Its job is to
accept the +12V (nominal) from the
36
SILICON CHIP
By MARQU E CROZMAN
plugpack supply and regulate it to the
DC voltage required to run the player.
Because it only uses low-cost parts,
the savings in batteries will very
quickly pay for this project. It's also a
snack to build and get going. In fact,
we reckon that even a rank beginner
could build this design.
The circuit can also be easily customised to meet your requirements.
Some personal players require two
AA cells (3V), while others require
three (4.5V) or even four (6V). For this
reason, we've designed the project so
that it can deliver either 3V, 4.5V, 6V
or 9V. All you have to do is select one
resistor value from a table.
An important safety aspect of this
project, particularly for beginners, is
that no mains wiring is required. Instead, it's designed to run from a car
battery or from a DC plugpack supply.
You can use any DC plugpack supply
with a rated output voltage of 9-12V.
However, the project is not just confined to powering personal players
from a DC supply. Because it was originally intended for use in a mainspowered project, the PC board also
has provision for a four-diode bridge
rectifier. By adding this bridge rectifier, the circuit can be powered from a
15VAC (or less) mains transformer.
In this application, however, the
02
1N4004
~.....__ _ _ _ _ _ _ _,-..,-•3V
D3
1N4004
10
+
16VW
-
Fig.1: the circuit is
based on an LM317
3-terminal adjustable regulator. The
output voltage can
be varied between
3V & 9V by choosing
the value ofR2, as
shown in Table 1.
LED1
OVO---,.__
___.,_ _ _ _ _ _ _ _ _ _...,.._OV
THE ELIMINATOR
TABLE 1
R2
Output
180 ohms
3V
330 ohms
4.5V
470 ohms
6V
750 ohms
9V
four diodes in the original bridge rectifier have been replaced by a single
diode (Dl) and a wire link. We don't
need the bridge rectifier, since we are
using a DC supply only.
Circuit details
Refer now to Fig.1 which shows the
circuit details.
As you can see, The Eliminator is
based on an LM317 3-terminal positive voltage regulator. This device is
capable of delivering up to 1.5A (with
adequate heatsinking), has an output
voltage range from 1.2-37V, and features internal thermal overload and
short circuit protection, In short, it is
virtually "blow-up" proof.
Let's take a closer look at how it
works. The+ 12Vrail from the plugpack
(or car battery) is applied to the input
of the LM317 regulator via reverse
polarity protection diode Dl. In operation, this regulator is designed to
provide 1.25V between its OUT and
ADJ (adjust) terminals but note that
the current flowing through the ADJ
terminal is negligible.
This makes the device extremely
easy to use, since we require just two
resistors to set the output voltage. Since
the voltage between the OUT and ADJ
terminals is fixed at 1.25V, it follows
that the current through Rl and R2 is
also fixed. This gives a simple formula
for the output voltage, as follows:
V001 = 1.25(1 + R2/Rl)
In our circuit, Rl is fixed at 120Q
while R2 is selected from Table 1 to
give the required output voltage. In
our case, we used a value of 180Q to
obtain a 3V output. If you want a 4.5V,
6V or 9V output, then just select the
appropriate resistor value from Table
1.
Alternatively, you could replace R2
with a lkQ trimpot to make the output
continuously variable over the 1.259V range.
A lO0µF electrolytic capacitor is
used to filter the incoming supply
PARTS LIST
1 PC board, code SC04104921,
48 x 61mm
1 aluminium case 100 x 58 x
45mm (Jaycar Cat. HB-5100)
1 Dynamark front panel label, 55
x 190mm
4 68A x 10mm machine screws,
nuts & lock washers
6 PC stakes
1 200mm length of medium~duty
hook-up wire
Semiconductors
3 1 N4004 diodes (D1 -D3)
1 LM317 voltage regulator
1 5mm LED (LED 1)
Capacitors
1 100µF 25VW PC electrolytic
2 10µF 25VW PC electrolytic
Resistors (0.5W, 1%)
1120Q
1 R2*
* The value of R2 must be selected ·
from Table 1 or a 1kQ trimpot can
be used instead
voltage, while the output of the regulator is filtered by a l0µF capacitor to
ensure stability. Notice also that the
ADJ terminal is bypassed using a second lOµF capacitor, to improve the
ripple rejection.
D2 protects the LM317 from any
reverse voltages which may generated
across the output by inductive or capacitive loads, while D3 discharges
the lOµF capacitor on the ADJ termi-
li:i
"'...
C>
~
u
c,i
ov--1
+T2v-
D1
~
9,oouF
+
Fig.2: the circuit is shown
here wired for a 3V output
but this can be varied by
changing the value of the
180Q resistor (see Table 1).
Mount the LM317 regulator
at full lead length & with its
metal tab adjacent to the
edge of the PC board.
Fig.3: here is the full-size etching
pattern for the PC board.
MAY1992
37
TABLE 2
Brand
Plug Size
Sanyo
1mm
Sony & Aiwa
1.3mm
Casio
1.6mm
JVC
3.1mm
Others: generally 2.1 mm or 2.5mm
Note: there is no fixed convention as
to which terminal is positive & which is
negative. Check the socket of your
player - there is usually a small
diagram next to it to indicate the wiring
polarity
The PC board is mounted on the base of the metal case & secured using machine
screws, nuts & spacers. Take care with the polarity of the external leads.
nal if the output is short circuited.
Finally, LED 1 and its associated
3300 current limiting resistor provide
power on indication.
Construction
All the parts are mounted on a small
PC board coded SC04104921 - see
Fig.3.
Begin the assembly by installing PC
stakes at the six external wiring points,
then install the wire link. You now
have to select RZ from Table 1 to obtain
the required output voltage. We wanted
an output voltage of 3V, so we used a
value of 1800 as shown in Fig.3. If you
want an output voltage of 6V, for example, just substitute a 4800 resistor
instead.
The remaining resistors can now be
installed, followed by the diodes and
the capacitors. Make sure that the diodes and capacitors are oriented ex-
actly as shown in the diagram.
Finally, the LM317 regulator can be
installed. Mount it with its metal tab
towards the edge of the board and
leave its leads at full length.
The completed board assembly is
housed in a small metal case which
also acts as a heatsink for the LM317
regulator. Mark out and drill the three
mounting holes in the base to accept
the PC board, then mount the board
using 5mm spacers, machine screws
and nuts.
When the board is in place, mark
the mounting hole for the LM317 on
the side of the case, then remove the
PC board and drill the hole to 3mm.
Carefully deburr this hole so that you
get a perfectly smooth surface, then reinstall the PC board in the case.
Fig.5 shows the mounting details
for the LM317. As shown, its metal tab
must be isolated from the case using a
mica washer and insulating bush.
Smear both sides of the mica washer
with heatsink compound before bolting the assembly together. When this
has been done, use your multimeter
(set to a high resistance range) to confirm that there is no connection between the tab and the case.
If the meter indicates a short, remove the assembly immediately and
locate the source of the problem (eg, a
piece of metal swarfmay have punched
through the mica washer).
Next, attach the adhesive label to
the lid and drill a hole to accept the
LED bezel. This done, mount the LED
in position and connect it to the PC
board using short lengths of hook-up
wire. Take care with the LED polarity
INSULATING
MICA
WASHER
·"·~)I
SCREW
r
Dllilill(3
----CASE
t
T0220
DEVICE
The
Eliminator
Fig.4: this is the full-size artwork for the front panel.
38
SILICON CHIP
Fig.5: the LM317 3-terminal
regulator must be isolated from
the case using a mica washer &
insulating bush. Smear all
mating surfaces with heatsink
compound before bolting the
assembly together, then use your
multimeter to confirm that the
metal tab has been correctly
isolated from the case.
correct - the polarity indication will
usually be moulded into the plastic
adjacent to the socket.
For in-car use, the input lead is
simply a length of figure-8 cable attached to a cigarette lighter plug. Again,
make sure that you get the polarity
correct. If a plugpack supply is used,
tbe input lead will come directly from
the plugpack itself. You can either
connect the plugpack supply to The
Eliminator via a DC socket mounted
on the side of the case or you can
solder the wires directly to the PC
board.
The LM317 regulator uses the case as
a heatsink. Make sure that it is
electrically isolated from the case as
shown in Fig.5 .
MARK ONE
COMMUNICATIONS
Specialising in:
Mitsubishi , Motorola &
NEC mobile phones
INSTALLATION &
SERVICE
7DAYS
.
Testing
Double check all wiring and component orientation before you assemble the case. All OK? If so, screw the
two halves of the case together and
connect the unit to your 12V power
supply. If everything is working OK,
the LED will come on. Check the output voltage and polarity with your
multimeter- it should be very close to
the selected value.
Alternatively, if you substituted a
lkQ trimpot for R2 , you simply adjust
the pot until you get the desired output voltage.
SC
- the cathode lead is the shorter of the
two (see Fig.1).
The assembly can now be completed
by installing the input and output
leads. These are fed through holes in
the ends of the case and secured by
cordgrip grommets. You will have to
fit the output lead with a DC plug to
suit your particular player (see Table
2) . Make sure that you get the polarity
obile Phone
18) 29 5888
18) 21 4555
275 Ryedale Rd,
Eastwood,
NSW2122.
Motorola Micro-T•A•C
Cellular Telephone
Phone (02) 489 7777
Fax (02) 489 7774
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MAY 1992
39
Five faults all at once!
A heading like that is hard to ignore. Likewise
the customer's claim as she went through the list
of faults. Superficially, at least, it was a
formidable list and I could only hope that it
wasn't as bad as it sounded.
The device in question was a
Panasonic TC-2969 TV set, an upmarket unit which first appeared about
four years ago although this particular set is only about three years old. It
is a 73cm model featuring, among
other things, an elaborate remote control unit.
·It has been a very popular set. My
dealer colleagues, between them, have
probably sold around 150 in this area
but the number of faults I have encountered has been extremely small.
This set belongs to one of my longstanding customers, an elderly widow,
but most of my dealings were with
her daughter and son-in-law, who
were better able to transport the set
and describe the various faults.
I have had one previous call to this
set but that was hardly the set's fault.
FRACAR
·AVE
•••
... more than $10. from every UHF
television antenna you buy.
Fracarro's
====-
4PUN
for better
performance
from weak
UHF
signals.
Peter C. Lacey Services Pty. Ltd.
P.O. Box 678 (74Fulton Rd.) Mount Eliza 3930
Tel:03 787 2077 Fax:(03) 787 3460 ACN006893438
40
SILICON CHIP
and enjoying a TV program when the
screen suddenly went black.
But it wasn't a shut-down as in
fault number one because the sound
was still running and there were traces
of the brighter colours on the screen.
This was something new and it fi~
nally convinced them to seek my help.
So there we had it - five different
intermittent faults. Naturally, there
wasn't any point in trying to tackle a
problem like that in a lounge room; it
had to come into the workshop. Fortunately, the son-in-law had a ute and
plenty of help on hand to load the set
into it. And so it finished up on my
counter.
About 12 months ago, it was the victim of a lightning strike to the power
lines which, as well as damaging the
set, knocked out a microwave oven,
the electric stove and the hot water
system. In fact, about the only thing
that escaped in the household was
the video recorder - a typical Murphy
touch.
My first insight into the problem Related faults
was a phone call from the owner's
Now tracking down any one of
daughter, who proceeded to list all those faults could be a nasty job. But
the faults it was exhibiting. And, as was tracking down five going to be
already intimated, it was a formida- any harder? Not necessarily. In fact, it
ble list.
didn't need Sherlock Holmes to deThe first fault appeared not long duce that all five faults were almost
after I had serviced it and took the . certainly related; find the cause of
form of occasional spontaneous shut- one and you'd probably find the cause
down; ie, the set would simply turn of them all.
itself off. But while this was mildly
That was the bright side. The dark
annoying, it wasn't regarded as very side was that it was still an intermitserious; it needed only a touch of the tent and likely to take a lot of time to
remote on/ off control button to turn it track down. I started by simply turnback on.
ing the set on as it came in and, sure
Fault number two caused the set to enough, the number five fault just
randomly change channels, again in- described was still in evidence; ie,
termittently and also easily remedied normal sound but a dark screen with
via the remote control.
just a hint of colour. And, by using the
Fault number three could be al- remote control unit, I could change
most rated as two faults: random channels, as evident by the sound.
changes of brightness, or the same
It is necessary to digress here, so
effect on colour saturation.
that the reader can follow the next
Fault number four was a fairly re- step. As is common with many upcent manifestation. It had happened market sets, this set's remote control
on only a couple of occasions but was system offers a multitude of functions;
somewhat more serious. As the daugh- far more than most people find necester described it, it was " ... a kind of sary and more than some people can
blurting noise; frighteningly loud. handle.
Nearly scared Mum out of her wits".
In this case, the controls include
And then she went on to describe the usual on/off button, 10 channel
fault number five which had occurred selecting buttons, an up/down button
the previous evening. She and her which takes the set through the chanhusband had been visiting her mother nels one-by-one, a button to allow a
channel number - up to about 30 - to
be keyed in, volume up/down, stereo
sound enable/disable, video up/down
and audio up/down.
Suitably activated, the video up/
down provides a choice of brightness,
contrast and colour saturation control. The audio up/down operates
similarly, providing bass, treble and
balance control. And any settings selected by these controls are held after
the set is turned off, or even unplugged
from the mains.
There is also a TV /VCR switch
which allows the control unit to be
used on a Panasonic VCR. It provides
all the usual VCR control functions:
stop, rewind, fast forward, record, etc.
Then there is a another group of
five buttons. Button 1 switches from
TV to video input; button 2 is a timer,
to shut the set down after a selected
time; button 3 displays the channel
number in the top right corner of the
screen; button 4 provides sound mute
(now what would anyone want that
for?); and button 5 is marked "N" (for
normalising).
Complicated? You bet it is. And
many a viewer has got himself into a
hopeless mess trying to cope with all
those facilities. In particular, it is all
too easy for the beginner to black out
the screen or mute the sound, and
then forget how to undo it and go into
panic mode.
Hence the above mentioned "N"
button, which is almost an admission
of the extreme complexity. It effectively cancels all the control instruc-
TETIA TV TIP
Samsung TV chassis No. PSOF &
RM101 (used in Samsung, Tempest, Akai and Toshiba models)
Symptom: picture size is small and
pulsates, never quite filling the
screen. The 125V rail is low but
shows no sign of fluctuation. Reducing the picture contrast stops the
pulsation but does nothing to increase the size.
Cure: STR30125 voltage regulator
IC defective. This is the main cause
tions that have been fed in and takes
everything - brightness, contrast, colour saturation, sound settings, etc back to their mid-position (or "normal") settings. From there, the user
can start all over again.
Back to the interruption
That brings us back to where I interrupted myself; with the set on the
bench with' normal sound but only a
few spots of colour on a black screen.
I hit the "N" button and up came
the picture with normal brightness,
contrast and colour. I then tried something else. Using the remote control, I
activated the brightness function and
wound it down to minimum, then did
the same for the contrast. And that
exactly duplicated the condition of
the set when it came in.
All this was quite significant. It sup-
of the small picture - the pulsation is
a secondary effect produced by the
low rail voltage on the Automatic
Beam Current Limiter. Resetting the
contrast has the effect of reducing
the beam current, so the pulsation
stops.
TETIA TV Tip is supplied by the Tasmanian branch of the Electronic Technician's Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston
Bay, 7015.
ported a theory I had been toying with
from the start: that the fault was not,
as might have at first been imagined,
in the remote control system itself.
Rather, something was "telling" the
microprocessor to do these things - in
this case to turn down the brightness
and contrast. That "something" could
be almost anywhere in the set. All I
had to do was find it.
I let the set run all day and every
day for about a week. During that
time, it exhibited almost all of the
faults listed above; all, in fact, except
fault number four (the distressing
blurting noise). More importantly, I
confirmed that these effects were totally random; they didn't appear to be
related to temperature, period of operation, operation of other appliances
on the same power circuit or, in fact,
anything that I could pin down.
But that very randomness created a gut feeling that it was due to a
dry joint somewhere in
set. The back was already
off the set and so, armed
with my favourite
sledgehammer, I set to
work. (The sledgehammer is really just a large
screwdriver, the plastic
handle of which is the
right weight to deliver
an appropriate blow to
the circuit board).
Looking into the back
of the set, there is a large
horizontal board, about
350 x 200mm, in the bottom of the cabinet. This
carries the power supply and the horizontal
and vertical output
MAY 1992
41
SERVICEMAN'S LOG - CTD
stages . On the lefthand side there is a
similar size signal processing board
which is mounted vertically. This carries the tuner, IF strip, stereo decoding, remote control processing (but
not the receiver), and the audio/visual
inputs and t;mtputs.
On the righthand side there is a
smaller board, about 150 x 100mm,
which carries additional horizontal
components and the pincushion correction components, etc.
I tackled the horizontal board first,
starting on the lefthand side, tapping
moderately hard and watching the
screen in the mirror. No joy. I made
my way across to the righthand side ,
again without any result until I tapped
the horizontal output transformer,
which is at the right rear of the board.
Suddenly, there was a reaction. I
can't remember which fault it was, or
whether there was more than one,
except that it probably changed channels. Anyway, it was what I was after.
Well, that was encouraging. The
only snag was , I couldn't repeat it. No
matter how hard I bashed after that,
there was no response. I left it for a
while , tried again, left it, tried again,
and so on for more times that I can
remember. The result was, at best,
"iffy"; a couple of times I achieved a
briefresponse but nothing consistent.
Nevertheless, it did seem to suggest
that the fault was not on the board,
but somewhere nearby, and that the
vibration I was imparting to the board
was being transferred to it.
So what was closest? There is an
"L" shaped aluminium plate near the
horizontal output transformer, best
envisaged as lying on its side, with
the longer section, about 200mm long
and 80mm high, running from the
back towards the front of the set. The
shorter section, about 40mm long, runs
parallel with the back of the cabinet
and provides the support.
One of this plate's functions is as a
heatsink for the horizontal output transistor, which is mounted towards the
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15% discount on two or more items.
SHORTED TURNS TESTER
Built-in meter to check EHT transformers including
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rear. It also carries a heavier, finned
heatsink at the front for the power
supply regulator IC and a couple of
large resistors. And when I tapped
this, ever so gently, the set "went
mad", changing channels and varying brightness, contrast and colour.
But then it, too, settled down and I
went back to the main board again.
But no joy here either. So over the
next few hours, in between other jobs,
I went through several tapping sessions. I achieved some briefresponses
but, more importantly, I concluded
that the aluminium bracket was the
more sensitive of the two, although
the point to be tapped was most critical.
And it was while I was establishing
this critical point that I encountered
fault number four; the blurting sound.
And it was only then that I fully appreciated why it had "nearly scared
Mum out of her wits". With my head
half inside the cabinet while I was
probing, it must have hit my eardrums
at about lOdB above the threshold of
pain and it came close to having a
more drastic effect on me than it had
on "Mum".
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42
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90 George St, Hornsby, NSW 2077.
Phone (02) 476 5854 Fax (02) 476 3231
What happened next was
I
')
more fortuitous than scientific.
I,,
The set was on a bench near
one of the windows and, in
the late afternoon, the sun
~
shines directly into my eyes. I
have a blind fitted to take care
of this situation and this darkened the area considerably but
.
.~
it was still light enough to see
,~-what I was tapping.
And so I had another go at
q~:==::.i--:;;-~·"V'·>
.•
the aluminium bracket. After
-~~~
a couple of tries, I found the
sensitive spot again and the
set gave forth with another
raspberry. This time, fortunately, I had moved back a
little, so it wasn't quite so traumatic.
oWl-,-H r,/\'-( 1-tG:Ai;> l~SI?~ "fl1E:
But, more importantly, I
INE:"i" J: E-Na::>ul\J"'t1::;..~e;D
happened to be looking at the
L.:
i 1\-\~ 1)\-Sl'f<G:S'SlNG
right spot at the right time.
"BLURTING NOi
The horizontal output transistor is in a TO-3 case, connected
quick fix was out of the question. And
to the main board via three flying SC5326, which uses the "Q" chassis.
leads. The base and emitter leads are The "Q" chassis is a mite long in the so the customer had no option but to
soldered directly to the appropriate tooth now; it first appeared at least 10 leave it with me.
pins but the collector lead is con- years ago and remained current, with
A little later, I turned the set on
nected to the case via a solder lug minor variations, for several years.
again and studied the problem more
secured under one of the mounting
This particular set has been through leisurely. I still couldn't make sense
the workshop several times, mainly of the hold control behaviour, so I
screws.
At the instant the system took off, I for minor faults, but is still in good decided to disconnect the line to the
was looking at this solder lug. And nick and has a few years of life left in sync separator and let the vertical circuit float. Normally, this would enthere it was - a tiny spark, clearly it yet.
Initially, the owner contacted me able me to roll the picture slowly in
visible in the subdued light. From
there on it was routine. Closer exami- by phone and, from the symptoms either direction and even hold it
nation confirmed that what was sup- described, it appeared that the pic- briefly (with a little care).
posed to be a soldered connection · ture was rolling very rapidly. When I
The vertical functions are provided
between the lead and the solder lug suggested that he try adjusting the by IC401 (LA7800) and the video and
was no such thing; it was a classic dry vertical hold control - on the front of sync pulses come in on pin 14 via
the set - he replied that he had done number of components, including
joint.
And that was it; a few moments that, but that it didn't seem to make R402 (220Q) which was fairly easy to
get at. It was also a convenient access
work with some flux and a hot iron any difference.
This clearly indicated that it was
point for the CRO and this indicated
produced a proper joint and all the
problems were solved. It was almost not a simple case of maladjustment, that the waveform was correct. So I
lifted the resistor and tried the hold
an anti-climax, except that I had the so I said "bring it in". When it arrived,
I switched it on for a preliminary check control again.
satisfaction ofknowing that I had fiwhile the customer was still there.
nally cracked it.
The result was rather strange. IniThis confirmed the customer's obser- tially, the effect was much the same as
But there was one puzzling aspect.
vations and also seemed to confirm before, with the picture rolling rapI would normally expect such a fault,
idly upwards. But it was now floating
in that position, to take out the tran- my interpretation of them; that the
sistor. So why had it survived? I dunno picture was rolling very rapidly up- and, by backing off the vertical hold
please; ask Murphy.
·
wards.
control, I was able to make it roll
I tried the vertical hold control but quite smoothly and under perfect conConfusing symptoms
it had only a very slight affect on the trol. Well, that was better than before.
My next story involves a 53cm AWA upward movement in one direction.
But it was when I tried to roll it
colour TV set and some very confus- Rotating the vertical hold control in slowly upwards that it baulked. I could
ing symptoms. Indeed, symptoms are the other direction then caused the hold the blanking bar at the bottom of
not always what they appear to be at picture to suddenly reverse direction the screen and move it slowly upwards until it was about half way up
first glance. And if you don't get the and roll rapidly downwards.
Well, I hadn't seen anything like the screen. At that point, it started to
symptoms right, well ...
The set involved is an AWA model that before and any suggestion of a jitter, as though the bar was bouncing
.
~
. ..
. be
~
~~
se::
a
MAY 1992
43
• C4,Z
3.Cf
41,3
sov
scv
3~
~30_..u
040
,.,_,z /2S0
/2SC20
66 o/2SC21
Fig.1: part of the vertical & horizontal output circuitry in the AWA SC5326. Transistors Q402 & Q403
form the vertical output stage & drive the vertical scan coils (at left) via capacitors C412 & C413.
against some obstacle. And the further up the screen I forced it, the
faster it jittered.
At this point, I suddenly realised
that I had been misleading myself.
What I had imagined to be a fast roll
was, in fact, a fast jitter. Of course, the
difference was academic as far as the
viewer was concerned but it was important diagnostically.
In any case, I wasn't particularly
worried. There isn't a great deal to
suspect in this part of the circuit and
I had already mentally cleared part of
it anyway. Most of the circuitry is in
IC401, which contains the sync separator, vertical oscillator, blanking circuit and the vertical drive.
The latter comes out on pin 6 and
goes to the vertical output pair, Q402
& Q403. These, in turn, drive the vertical scan coils. And it was everything
from pin 6 to the scan coils that I had
mentally cleared, on the simple basis
that both the height and linearity,
checked on a test pattern, were perfect.
So was it the chip? I did a voltage
check of all the pins and found nothing abnormal. I then checked the various minor components around the
chip but again drew a blank. That
threw suspicion on the chip and, since
I had some in stock, it was easy enough
to fit a new one. But, alas, still no joy.
As far as I could see, that didn't
leave anything else to check. It was
44
SILICON CHIP
time to seek help. I rang one of the
service technicians at AWA, described
the symptoms and told him what I
had already tried. He wasn't at all
fazed by my story and immediately
suggested two other components: capacitor C421 (220pF) across the scan
coils and C588 (1000µF) across T573
in the pincushion circuit. He explained that both these components
could give trouble and create symptoms similar to those I had described.
So, full of hope, I changed both of
them. But I drew another blank; it
made absolutely no difference. And
that really put the ball back in my
court. I could hardly ask for more
help; it was obvious that this was all
that was known.
But the advice had done some good.
... A CON\/G:t-.llli.N""i'
AcCG:~':S ?DIN, FOR
.,.-1-1e;. C. 'RO .. o
It had broken through a mental barrier which had excluded anything in
the output stage from my thoughts. If
one component in this section could
cause these symptoms, then why not
another? And that brought me to capacitors C412 & C413 (330µF, 50V) in
series between the output pair (Q402
& Q403) and the scan coils.
I've often puzzled over this arrangement. Some models used only one
capacitor, others the two-in-series arrangement (not back to back). Anyway, in desperation I pulled them both
out and fitted two new ones. And
bingo! That was it; everything was
now back to normal.
But the reason remains a mystery. I
checked both capacitors on the capacitance meter and they both read
full value. Nor did there appear to be
any leakage, at least at the test voltage. Nevertheless, I suspect that leakage may be the answer - after all,
what else can go wrong with an electrolytic? Or was one capacitor partially open circuit?
And what was the reason for the
two ·capacitors in series? Had leakage
proved a problem in early versions,
with only one capacitor, and had
someone decided that two would reduce the risk? The reasoning, of
course, would be that one could fail
without creating a problem, while the
chances of both failing would be quite
small.
SC
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A huge data book listing dala for thousands of transistors,
as well as alarge equivalent section. The book is designed
for the engineer and technician.
section 2 lists manufacturers names and addresses.
section 3 is the huge alphanumeric listing of lransistors
with specifications..
section 4 lists FETs with specs.
section 5 covers injunction transistors.
seclion 6 is the substitution guide.
section 7 covers devices with prefix CV.
section 8 lists 100's of transistor outline drawings and
terminations..
242 17
x 0mm.
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Four fabulous new books published by Micro Tech
for Elektor Electronics. Each book has 300 circuits
aimed at the electronic enthusiast, professional or
s
amateur. They offer a comprehension collection of
practical ideas, concepts and developments, many of
which have been in annual Eleklor magazines. You
will find circuits for audio and video, car, cycle and
motorcycle, home and garden, receivers and aerials,
hobbies and games, measuring and testing,
oscillators and generators, current sources and
power supplies, microcomputer and music electronics and more.
300 Circuits cat BM-2470 $19.95
301 Circuits cat BM-2471 $19.95
302 Circuits Cat BM-2472 $19.95
303 Circuits Cat BM-2473 $19.95
To give you an example of these circuits - the 303 circuit book includes 32 audio and Hi Fi projects, 14 circuits for cars and bicycles,
43 computer and microprocessor circuits, 11 electronics projects, 24 HF and VHF circuits, 16 circuits for anumber of hobbies and
pastimes, 54 projects for home and garden, 29 po.yer supply circuits, 29 circuits for test and measure men I equipment, 9 TV and
video project, as well as 42 design Ideas
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Install your own wireless burglar alarm and don't pay an arm and aleg! The EG100 is made by Zeus, the same people
who make our current wireless system, in fact, all the same wireless extras will work with this panel. The EG100 is a
key operated signal sector panel which accepts not only the wireless PIRs etc, but you can hard wire detectors as well.
Eg 2 wireless PIRs, 2 wireless door/Window transmitters and a wired PIR will all work very happily on the one sector.
This is the lowest prices wireless panel we've seen that is TOP QUALITY. There are plenty of junky ones around that we
just won't sell. Aller all, aburglar alarm that false triggers is no good to anyone.
FEATURES: • Low cost • DIY installation • Acceplswireless and wires sensors • Tamper proof protected JLED
indicators • Keyswilch arming with exit delay time • Instant alarm when sensors triggered • NG and NO relay output.
SPECIFICATIONS: • Operates on 303-875MHz • System codes 4,096 • Transmitting range 50 metres (open space) •
30 second exit delay • lnslant entry delay.
ACCESSORIES: • Backup battery 1.2A 12V cat SB-2480 $26.50 • Wireless passive infra red detector Cat LA-5205
$129.95 • Door/Window reed switch Cal LA-521 O $69 • Siren 12V DC Cat LA-5700 $28.50 • Strobe tight Cat
LA-5300 $32.95 • Wired PIRs from $49.95.
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FOR BATTERIES?
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White TV Coax Sale -
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30mt Rolls
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our
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NiCad
batteries,
Vinnick so
you know
the quality
you'll be pleasanlly surprised.
There are lwo ranges available: Long life general
purpose and Gold Extra Heavy Duty Zinc Chloride.
while coax. 3C2Vstyle in
convenient 30ml rolls. Meter
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30mt roll price normally $1 4.95.
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cat SB-2331
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Cat SB-2341
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Discharge rates for Gold Extra
Pkt4
Pkt 2
Pkt 2
Pkt2
Pkt 1
$2.50
$2.75
$2.75
$3.25
$1.75
Heavy Duty
Size Norn
AM 1.5V
AA 1.5V
1.5V
C
1.5V
D
Cutoff
0.85V
0.75V
0.75V
0.75V
Load
15 ohms
4ohms
4ohms
4 ohms
Mins of service
280mins
190 mlns
480 mlns
910 mlns
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your surplus stocks of
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$
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112
That's only 36 ~ per meter
U\!l~ AUDIO LEADS
3.5 stereo plug to 2 x RCA plug. 1 .2mt long .
$4. 95
(02) 743 5222
$4.50
.______ii'
Cat WA- 1024
~EUt !~~ICON~,UCT&RS
4060 14 stg count.div +oscil ZC-4060
LM358 Dual op amp
ZL-3358
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components and
equipment. We are
continually on the lookout
for sources of prime
quality merchand ise.
Call Mark
Harris or Bruce
Routley now
3.5 stereo plug lo 3.5 stereo plug. 1.2ml long.
catwA-1022
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$1.20
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PRODUCT SHOWCASE]
Scope programmable
alarm has six sectors
This is a professionally designed
and built alarm panel with six sectors
and highly flexible programming, via
the 12 button keyboard. As many as
51 separate facilities can be programmed but if you just want of use it
as a standard 6-sector alarm, no programming is required.
Two manuals are supplied with the
unit: a basic instruction manual and a
114 page installation & service manual
which has all the details of programming.
Inside the case there is plenty or
room for wiring and a standby battery.
The complete system, less mains
plugpack and standby battery, retails
for $199.50. Or you can purchase just
the printed circuit board, if you want
to mount it remotely. In that case the
PC board costs $129.50 plus $49.95
for the intelligent remote keypad and
7-segment display.
For further information, contact
your closest Jaycar Electronics store
or phone them on (02) 743 5222.
Handy magnifier for
PC board inspection
Do you have trouble inspecting your
solder joints on printed circuit boards.
This handy magnifier makes the job
much easier, whether or not you normally wear glasses. The magnifying
lens is 115mm in diameter and its
In-circuit
fault finder
The new T1500 from Polar Instruments is specifically designed
for troubleshooting unpowered PC
boards. It will test any kind of
component, including linear or
digita'l. LCs, tFansformers, relays,
discrete transistors and capacitors.
To test a suspect component, a
pair of probes is placed across it.
This applies a small AC voltage
across the component and the
Lissajous pattern resulting from
plotting voltage and current is displayed on the screen. This can be
compared with the normal pattern
for the component (Polar calls it
the "dynamic signature" of the
component) which can then be
accepted or rejected.
The T1500 has four ranges and
two test frequencies to cope with a
wide variety of components. By
using the dual channel comparison technique, users can identify
if the component is good or faulty.
This allows operators with lim-
ited technical ability or poor documentation to locate faults to component level.
For more information, contact
Mark Breznik, Emona Instruments,
86 Parramatta Road, Camperdown,
NSW 2050. Phone (02) 550 1378.
MAY 1992
53
cleaner removes dirt from keyboards,
monitors, printers and PC boards. Several attachments are included.
5.25-inch and 3.5-inch cleaning
discs (wet type) are provided for removing dirt from read/write heads in
drives. For more information, contact
Rod Irving Electronics at their Stanmore or Melbourne stores.
Protect your valuable issues
Silicon Chip Binders
New catalog of HP
power supplies
fold-up stand makes it quite convenient to work with. Use it in conjunction with a desk lamp for even more
ease of use.
It is priced at just 13.95 from David
Reid Electronics, 12 7 York Street, Sydney 2000. Phone (02) 267 1385.
These beautifully-made binders
will protect your copies of SILICON
CHIP. They feature heavy-board
covers & are made from a
distinctive 2-tone green vinyl. They
hold upto 14 issues& will look great
on your bookshelf.
Clean-up kit for
computers
* High quality
* Hold up to 14 issues
* 80mm internal width
* SILICON CHIP logo printed
in
gold-coloured lettering on spine &
cover
Price: $A11.95 plus $3 p&p each
(NZ $6 p&p). Send your order to:
SIiicon Chip Publications
PO Box 139
Collaroy Beach 2097
Or fax (02) 979 6503; or ring (02)
979 5644 & quote your credit card
number.
Use this handy form l
----------Enclosed is my cheque/money order for
$_ _ _ or please debit my
□
Bankcard
□
Visa
□
Mastercard
Card No:
Card Expiry Date _ _/_ _
Signature _ _ _ _ _ _ _ __
Name _ _ _ _ _ _ _ _ __
I
I
I
I
I
I
I
I
I
I
I
I
I
.___________ .
Address _ _ _ _ _ _ _ _ __
_ _ _ _ _ _ _ P/code._ __
54
SILICON CHIP
Surprising as it may seem, your
computer constantly acts as a vacuum
cleaner, drawing in dust particles via
the cooling fan. This dirt then settles
on the drives, discs and boards. This
cleaning kit from Rod Irving Electronics addresses the dirt problem.
The kit has everything to clean your
machine inside and out. Doubleended cleaning wands reach into crevices and antistatic cleaning pads remove dust and help in keeping it away.
The battery operated mini vacuum
Hewlett Packard has just released a
new catalog of their DC power supplies and electronic loads. An introductory section outlines important
aspects in selecting a supply for specific applications and a quick reference to the line of DC supplies is also
included.
Among the programmable supplies
in HP's range are single and multiple
output units and a mainframe with
interchangeable modules. Programmable electronic loads are offered as single input models or as modules for
use in the mainframe.
For more information, contact the
Customer Information Centre, Test &
Measurement, Hewlett Packard Australia Ltd, 31-41 Joseph Street, Blackburn, Vic 3130. Phone (008) 033 821.
.,.s~.,.i;;i:.i;~
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.
Electronics Workbench®
The electronics lab in a computer!
MH series amplifier (left) & PSU1 piggy back supply unit.
New masthead amplifiers & splitters
from Hill Industries
There are five models in this new range of MH series
masthead amplifiers from Hills. The units are designed
to cover a wide variety of applications in both the UHF
and VHF frequency bands. All amplifiers have a filter
which rejects FM (band 11) signals. If the unit is required
to amplify FM signals as well, the filter is rendered
inoperative by cutting a link.
Each MH series masthead amplifier consists of two
units. The amplifier itself is installed on the antenna
mast and is housed in a
black weatherproof box. A
U-clamp arid wing nuts secure it in place while the
power supply comes in the
form of a plugpack which
can be 'piggy backed' with
the TV's power plug (see
photo). Thus, both the TV '
and the masthead amplifier The Extraset 1-4 amplified
are powered from the same splitter.
socket. The power supply
unit sends the amplified signal to the TV via coaxial
cable. It also has provision to supply signal to a second
TV.
If you need more TV or FM outlets, the Hills range of
Extraset amplified splitters could be answer. There are
two models. Extraset 1-4 is a self contained mains-powered unit for use in locations with ready access to 240VAC.
The other, Extraset 4LP, is a line-powered 2-part unit
consisting of the amplifier and a 'piggy back' power
supply for use where access to 240VAC is more difficult.
Both units have a single antenna input and four outputs
for TV or FM radio use.
Both the masthead amplifiers and the amplified splitters
can be easily installed. For more information, contact
Hills Industries, 944-956 South Road, Edwardstown, SA
5039. Phone (08) 297 3888.
New transistor
mounting washers
This new range of transistor
mounting washers allows you
to dispense with that messy
process of applying heatsink
compound. Why didn't somebody think of it before?
They have a high voltage rating and come in the common
sizes - TO-220, TO-3, TO-3P and so on. They are available at all Jaycar stores.
C>
A simple, intuitive and very
powerful teaching tool, Electronics Workbench lets students and
hobbyists design and test both
analog and digital electronic
circuits, without the delays and
expense of a laboratory,
THREE VERSIONS
• Professional Version : EGNVGA
colour display; unlimited components
• Personal Plus Version: Monochrome display ; unlimited components
• ·Personal Version: Monochrome
display; limited to 20 components per
circuit
FEATURES
• Quick and simple circuit entry
• Digital and Analog Modules
included, complete with all components • Simulated instruments: dual
trace scope, spectrum analyser,
function generator, multimeter, digital
word generator and logic analyser
• Complete control over all
component values and parameters
• Print: circuit schematics, parts list,
instrument readings, macros • Logic
conversion - truth table to Boolean
formula to logic gates • Customisable hypertext help system
EMONA
INSTRUMENTS
NSW ......................... (02) 519 3933
VIC ........ .. .......... ........ (03) 889 0427
OLD :......................... (07) 397 7427
DISTRIBUTORS
Perth .. ... ... ... .... ...... ......... (09) 244 2777
Adelaide .................. .. . (08) 362 7548
Hobart .. .................... .. .. . (002) 34 2233
EmonaLAB4
Four instruments in one package!
The LAB4 has four full
function test instruments :
■
DC POWER SU PPL V
Triple output; 5V, 15V, 0-S0V
■
with neatly laid out and labelled
front panel controls. Also, the
LAB4 is compact and only takes
up a small space, compared to
four bench-top instruments.
DIGIT AL MULTI METER
Full function, auto-ranging
■ FUNCTION GENERATOR
0.02Hz-2 M:-iz , with SWEEP
■
FREQUENCY COUNTER
1Hz-100MHz input range
INDEPENDENT INSTRUMENTS
Each instrument in the LAB4 is
completely independent and can be
switched ON or OFF as required.
The LAB4 has only one 240V mains
input, saving on multiple power
points.
Each instrument is clearly defined
EMO
NA
INSTR UMENTS
NSW ...... .. ............ ..... (02) 519 3933
VIC ... ........ ... .............. (03) 889 0427
OLD .......................... (07) 397 7427
DISTRIBUTORS
Perth ... .... .... ..... .. .. .. ...... (09) 244 2777
Adelaide ..... .. ............... .. (08) 362 7548
Hobart ............. ............. . (002) 34 2233
MAY
1992
55
Balanced line receiver
for audio applications
sional and automotive audio equipment, as well as industrial applications. For more information, contact
Ian Laidlaw at NSD Australia, 205
Middleborough Road, Box Hill, Vic
3128. Phone (03) 890 0970.
tronics, 127 York St, Sydney 2000.
Phone (02) 267 1385.
Micro drivers for
teensy weensy screws
Engrave your valuables
with the Easy Etch
The SSM-2143 from Analog Devices
is a balanced line receiver system for
audio and industrial applications requiring high immunity from electromagnetic interference (EMI). It has a
differential gain of0.5 and has a common-mode rejection at 60Hz of -90dB
and -85dB at 20kHz.
Housed in either an 8-pin mini-DIP
or SOIC package, the device complements the SSM-2142 balanced line
driver. Together, they provide a high
performance solution to driving and
receiving audio signals over long cable runs in noisy environments.
Two gain options (2 or 0.5) make it
flexible for use in consumer, profes-
With the ever-present risk of theft,
it's a good idea to engrave your household valuables with your driver's licence number. This is only one of the
possible uses of the Easy Etch Engraver. It has a steel bit and is suitable
for engraving metal, plastic and wood.
Replacement bits are available.
The unit is powered by a 12V
plugpack and retails for $34.95. For
more details, contact David Reid Elec-
PRESTON ELECTRONICS
217 High Street, Preston, Melbourne
Victoria 3072
(Cnr of Bell & High Street)
Quantum 50-Meg SCSI Hard Drive (1 only) $295.00
Fujitsu 240V Coil Relays, DPDT 30A
$9.95 ea
Fujitsu 5V Relays, SPOT Subminiature
2764 Surplus Computer EPROMs, Erasable
$19.95
$3.95
27128 Surplus Computer EPROMs, Erasable $4.95
27256 Surplus Computer EPROMs, Erasable $5.95
27512 Surplus Computer EPROMs, Erasable $6.95
QC-191 O Super Tiger 5MHz Oscilloscope
$29.95
TEEPROM EPROM Writer Card/Cable + Software
To Suit IBM-Compatible Computers
$39.95
ff
Mail Order Hot-Line
8/Card-Mast/Card-Visa heque
Phone (03) 484 0191
56
SILICON CHIP
Most enthusiasts probably have a
set of jewellers screwdrivers which
let them do work on most miniature
equipment but this set of drivers is for
really tiny screws that the standard
types are too big for. There are seven
drivers in all with tip sizes of0.6, 0.7,
0.8, 1.0, 1.2, 1.4 and 1.6mm.
They would be particularly handy
if you are working on tiny brass model
locomotives or their equally tiny motors and gearboxes. The set of dr.ivers
is available from Rod Irving Electronics at their Sydney or Melbourne
stores.
PCB faults & shorts locator
from Emona Instruments
The Polar 850 shorts locat!Sr allows you to pinpoint
short circuits on PC boards in a fraction of the time it
normally takes. By locating solder bridges, etching defects, faulty ICs or faulty decoupling capacitors, the 850
also eliminates the need to cut tracks to isolate the fault.
Three different techniques are employed to track down
short circuits. 2MQ, 40MQ and 200MQ ranges allow
shorts to be located between PC tracks or component legs
by finding the point
of minimum resistance. For higher resistance faults, a 2mV
range with lµV resolution allows the tracing of current flow
along tracks. Finally,
a magnetic field sensing current probe
traces current along
inaccessible paths such as through ICs or through buried
tracks in multi-layer PC boards.
A variable pitch tone and a digital display are used to
guide the user to the shorted location. For more information, contact Mark Breznik at Emona Instruments, 86
Parramatta Rd, Camperdown, NSW 2050. Phone (02) 519
.3933.
SC
VISIBLE LASER
DIODE HEAD
JmW GAS LASER
SOLAR PANEL GIVEAWAY
Sui t teachers. doctors,
bus inessmen, and other
professionals. Improve
an d enhan ce all you r
presentations. Not a kit.
but a complete
commercial pen sized
laser poi nter at an
inc redible in troducto ry
price !
$199
ON LY
Small pen sized body.
Ru ns on two sma ll AAA
b atte ry. Batte ry life : 2-10
hours. Vi sible 5mW red
(670nM) laser. Proj ects a
Brand New high
quality US made,
amophourous glass
Solar Panels.
Dim ensions: 150 X
150 X 2.5mm . In
normal sunlig ht they
deliver a full 1 Watt
whilst charging 6V-8V
batteries! Can be
co nnected in ser ies,
in parallel. or series I parallel, to inc rease the vo lta ge,
and/or cu rrent capacity. For example, in average
sunlight , two of these panels connected in se ries will
deliver approximately 150mA of charging current , into a
floating 12V (14V) battery: 2 Watts' Four panels can be
connected in seri es paralle l to deliver 300mA into a
float ing battery : 4 Wat ts ' Comp are the prices ' All the
panels . have a weat her
INCREDIBLE PRICING:
protection film on rear, and the
terminat ing clips are provided.
ea. or 10 fo r $75
s9
than 50 metres. As used
for medical treatm ent by
so me doc tors and
acu punctu rists.
.
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.,
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A high q uality laser beam
di verging (beam
expander) glass lens,
mounted on an alum ini um
plate, with mounti ng
screws provided.
Dimensions: 25 X 25 X
6mm. Use it to ex pand
the laser be am fo r
Holog raphy, Special
Effects, or one of th e two
Small black anodised
metal body. Removable
pressure switch. Vertical
and horizontal adju stments. Batte ry li fe more
than 10 hours continuous .
5mW 670nM cl ass III A
laser. Range is about
150m, some wou ld claim
three ti mes more. Shock
teste d to 20009 . One year
warranty. ON LY
s9,9Q
SILICON
SOLAR CELLS
~m11int~
High efficiency silicon
ce ll s. With normal
su nlight. and under load .
ea ch on e of these 12.5 X
50m m ce ll s wil! de live r
0.46V at approximately
175mA: V o/c = 0.58V, I
sic = 188mA. Glass from
a ve ry small picture
frame, an d some silico n
coul d be used to make a
6V / 1. 1W (14 ce ll s) or a
t 2V / 2.2W (28 cells) solar
pan el! Pretinned
co nnec ting solder
co nnect ions are provided.
ON LY
5
1
ea.
EXPERIMENTAL ·.
E.H.T. POWER
SUPPLY
,·
s299
Price includes one rifle or
pistol mount
135
ARGON LASER
99
A very small telescopic
monocular IA viewer. Actually
1
h of the IA Binocular Vi ewer,•.~};iiii~
advertised els ewhere in this
advertisement. Very small:
Length of scope is 130mm
without the rubber hood fitted .
The assembled scope has
high quality military grade
optics, and employs a
prefocussed IA image
converter tube. This tube has
a useful response from
600-1300 nM , thus also making it useful when working
with IA LEDs, and JR laser systems. The scope has
provision for a coaxial E. H .T. connect ion, and is su pplied
with a power supply k it, t hat features a ready assembled
inverter on a sma ll PCB. The power supply easi ly fits
into a small plastic case, and can be fitted with a belt
r::fc1i~~s~i5i~;';'!i:1d~a1~:!
~;;;,~~tbo s239
MAINS OPERATED
LASER
lenses requi red to fine
focus a laser be am, for
Su rveying and Bar Code
Reading .
s
NIGHT VIEWER BARGAIN
visible red spot at more
DIVERGING LENS
Includes high quality low
divergen ce Siemens lase r
head with an output at
about 3mW an d one of
our reliab le and effic ient
12V un iversal laser power
supply kits. The tube is
used but it is guaranteed.
The kit co mes with full
instru ctions and it even
includes a prewou nd
transformer. The applications include high power
laser poin ters, surveyi ng
equipment, optical
ex periments, educatio n,
holography, medical
field , disco
s
displays, etc. ONLY
Save. by mak in g your own
laser poin ter. las er gu n
sight. medical treatm ent
laser. etc. Produces a well
collimated beam .
Designed to be powered
directl y from a 3V batte ry.
or from hig her voltages. if
a simpl e co nsta nt sou rce
is added. Simple circui t
included . 5mW (670nM) .
At an incredible
introductory
pri ce of :
For th e head only: Add $8
for the .ex tra "bits"
needed to make a
complete laser diode
pointer. Case, switch,
alkaline batteri es, and
battery holders.
Eve rything yo u need to
make a complete, self
con tained, visible ·Iaser
poin ter or gunsight.
Con sider thi s Mains
Powered Lase r Bargain ,
for discos, laboratories.
photography,
holography, medical
field, etc. Supplied with
two 3mW Sei me ns
tubes. and a brand new
potted mains laser
power supply. Th~
:~,~~~
3
5
189
f~=~~~i!Yu~~e iu~~~~\~;~tfe
We can also supply the mains lase r supplies wi th lower
powered tube. at a slightly lower cost. Ring or fax .
KIT SPECIALS
INFRA RED
FILTER
LCD DISPLAY
MODULE
These are brand new 16
character by 2 line
mod ules (16 X 2). has
back lightmg prov ision
High quality. high
contrast. alphanumeric
LCD display modu les.
with surface mounted
control c irc uit ry already
moun ted underneath the
PCB. Require a few
m1llamperes at 5V to
operate. We include
infor mation .
ON SPECIAL AT
s1s
LENS ASSEMBLY
This plastic
len s
assembly
includes a
lens with an
ap!Noximate
diam eter of
12m m. whos e focal point
is about 1h th e length of
the cylindrical tube. which
is 20mm long. Moun ting
holes provided . Great for
housin g an d imp roving
th e sensit ivity of any
~i~~c~~~s.laser
These air cooled Argon
Laser Heads have had
re lati vely " low hours" of
operation . They are
guaranteed . They produce
a bright blue beam
(488nM) and have a
power ou tp ut in the
10-100mW ra nge. Lim ited
supp lies. at a small
fraction of the ir real value.
ssoo
ONLY
T he head includes powe r
meter ci rcui try an d
starting circuitry. Circuit
diagram provided. Also
provid ed is a circ;:uit for a
sim ple power supply. We
can prov ide th e maj or
compon ents for this
s upply. En quire.
ea.
s5.50
/?1~
,·
'$. t'
.
High qual ity military binocular IA viewer. Self
powered. and ori ginall y
intended to be moun ted
on a helmet. Foc us Is
adJustable from 1 metre to
infinity. Requires some IA
illum ination . Powered by
one single 1.5V battery.
Ori ginal fibreglass carry
~f~~td s~~dce/. s549
0
IR LASERS
A high quality. milita ry
grade. deep infra red (IR)
filter. For medium and
high power incadescent
spotlights and flood lights.
Approximately 130mm
diameter and 6mm th ic k.
High temperature pyrexglass base material.
Excellent for night
surveillance equipment!
Works wlth IR viewers
and so me video
eg'/tfPeE~ IA L AT
s55
This preci si on
coll imator assembly
was removed from
work ing laser
printers. bu t is
supplied wi th an
extra Brand New
laser diode to sur t. It
produ ces a be am that
can be focussed to a fin e dot or hne Barel y vIs1b le. 780
nM/SmW. We also supply a PCB components and
instructions kit. for a suitable digit al driver circ uit that
can be used to complete the la se r transmitter
Suitable for commun ications. data lin ks. perimeter
e;;:~~~os~oi::. code reading. medical . etc .
s59
LASERS are not for kids:
DANGER
Melbou rn e Distributor : Electronics World
(03) 723 3860 or (03) 723 3094
ULTRASONIC
CAR ALARM
Crystal locked ult rasonic
movement detector and/or
a self stand ing ca r alarm.
Provision for bonnet/boot
protection and battery
back up. See S.C. May
'88. The kit includes the
PCB and com ponen ts. the
ultrasonic tran sducers.
but the screw terminals
are not provided.
CLEAR AN CE AT
$24.90
THE
MICROPHONE
This un it has a bu ilt in
preamplifier so it can
drive any amplifier. Turn
your stereo amplifier into
a PA amplifi er. Also
features to uch switch ing ,
battery c heck fun cti on.
etc.
See EA Nov. '86.
CLE ARANCE AT
5
19.90
MAY 1992
57
Build this
telephone intercont
Do you have a couple of old telephones
sitting in your junkbox? This simple
project will turn them into a useful
intercom unit that works just like a real
telephone system.
By GREIG SHERIDAN
Ever wondered how Commissioner
Gordon managed to raise Batman so
effortlessly on the hotline? Or have
you ever been curious to know how
the White House-Kremlin hotline
works?
Both systems are probably very
similar in concept to this telephone
intercom - ordinary telephones connected to 2-wire lines and featuring
full-duplex operation (ie, simultane58
SILICON CHIP
ous 2-way conversation). As well, this
unit is simple to drive, easy to build
and doesn't cost the earth!
As well as an intercom, this interface is capable of testing telephones,
modems, DTMF decoders and facsimile and answering machines. It is
also ideal for theatrical applications.
A stripped-down version could also
be used to make role-playing training
sessions more realistic at telephone
counselling services. In fact, this is
the purpose for which the circuit was
initially designed.
Telephones - an introduction
A telephone in its on-hook (hung
up) state exhibits a capacitance and
series resistance between both legs of
the line. This is the ringing circuit see Fig.1. An AC ringing signal will
pass and cause the bells to ring or the
"tone ringer" to warble.
When the phone is taken off-hook,
a DC loop (mainly resistive) is applied to the line and DC flows, fed
from the exchange. The exchange
equipment detects this current flow
and either stops the ringing signal (for
an incoming call) or sends dial tone
(if it's an outgoing call attempt).
When a phone is rung, the ringing
signal is connected to one leg of the
line and the return path is through
and frequency are not critical.
For applications where a
higher ring voltage is required
(generally the 800 series
phones and their Bakelite
predecessors), a larger ring
transformer can be used.
As well as the Arlec 75XXX
and Know how 7VA transformers, the circuit board has been
designed to accept the Farnell
T
150-07X 6VA series. The
I
I
Farnell 24-0-24 (150-076) rings
..J..
RL1
RL2
an 800 series telephone much
more convincingly.
For those who want to go
L - - - - - - - - - - - 4 - - S~P~Y
over the top, replace the power
Fig.1: the basic telephone ringing circuit.
supply shown here with an
When one phone is taken off-hook, the ring
ex-Telecom 50V supply (comrelays in the other loop close & a ringing
plete with 75V ring). These
signal is applied to the second phone.
supplies occasionally pop up
at electronics disposals stores
the DC supply. The idle line voltage is for a fraction of their "new" value.
usually around 48V, although this is
To operate the intercom, you simnot critical.
ply lift one phone and the other phone
When the phone handset is off- rings. Lifting the second phone then
hook, a current of 20-30mA flows.
stops the ringing and conversation
This is sufficient to power the phone's can commence.
transmitter (microphone) , whether it
The circuit does not reset until both
is a modern electronic type with an telephone handsets are replaced. This
in-built preamplifier or the original prevents the first phone to be hung up
carbon granule type.
from ringing until the second phone
This loop current also powers any "clears". It also allows one party to
dialling circuitry where appropriate.
hang up and continue the conversaThis circuit emulates the above con- tion on another extension on the line.
ditions, which makes it compatible
Circuit details
with just about all types of telephone.
However, there are a couple of deviaFig.2 shows the full circuit details.
tions from standard telephone prac- All the required voltages are derived
tice.
from two power transformers. One
First, the circuit described here uses transformer (Tl) provides a +12V rail
a negative earth whereas telecommu- (via D5 and a 3-terminal regulator) for
nications equipment generally runs the logic and around 46V DC for the
on a positive earth. This convention telephone "speech" voltage. The secwas chosen to minimise electrolytic ond transformer (T2) produces around
action in earth stakes and the like but 90V peak-to-peak (nominally 30V
as this is not applicable here, it has RMS) for the ring signal.
been omitted. Besides, I hate trying to
The whole circuit uses only four
think and design for a positive earth.
CMOS chips and two optoisolators to
The ring voltage and frequency have provide the logic and generate the
also been altered to keep the project required ringing signal. Let's see how
easy to build and the cost as low as
it works.
Schmitt inverter stages ICla & IClb
possible. The normal exchange ring
signal is 75-90V RMS at 25Hz but, by provide buffering and false triggering
experimentation, it has been found protection for phone 1. In the idle
that this voltage and frequency are state, there is no DC flowing in the
only required when driving older tele- phone line and so the LED in the
phones with real bells.
associated optoisolator (IC5) is off.
Modern telephones usually rectify ICla's input is thus held high, which
the incoming ring signal and regulate means that pin 12 ofIClb is also high.
it to about 12V, which then becomes
Similarly, if phone 2 is on-hook,
the power supply for the ringer chip . pin 10 of ICld will be high. These
So, for these phones, the ring voltage logic highs are fed to pins 5 & 6 of
PARTS LIST
1 metal case, 256 x 155 x 76mm
(W x D x H)
1 PC board, code SC12105921,
132 x 102mm
1 PC board, code SC12105922,
105 x 103mm
1 mains cord & 3-pin plug
2 15-0-15V 7VA PC-mounting
transformers (see note 1)
1 600:600 ohm transformer
(Arlec 45035, Altronics M1000, Jaycar MA-1510).
2 12V DPDT relays (Jaycar SY4061 or Altronics S-4165)
2 LED bezels
1 4-way screw terminal panel
1 100kO 10mm horizontal trim pot
19 PC stakes
1 cordgrip grommet
1 solder lug
Semiconductors
1 74C14/40106 hex Schmitt
inverter (IC1)
1 4081 B quad AND gate (IC2)
1 4001 B quad NOR gate (IC3)
1 4017B decade counter (IC4)
2 4N25 optoisolators (IC5,IC6)
4 BC547 NPN transistors
(01 ,02,03,05)
1 BC557 PNP transistor (04)
7 1N4004 diodes (D1-D7)
4 1N914/1 N4148 diodes (D8D11)
2 3.3V 1W zener diodes (ZD1,
ZD2)
1 5mm green LED (LED 1)
1 5mm orange LED (LED 2)
Capacitors
1 3300µF 63V PC electrolytic
1 1000µF 35V PC electrolytic
2 10µF 25V PC electrolytic
3 1µF 25V PC electrolytic
Resistors (0.5W, 1%)
3 100kO
2 6800
2 47kO
3 2200
6 10kO
2 1500
21.2kO1W
Miscellaneous
Machine screws, nuts & washers;
hook-up wire; two telephones; 2way telephone cable.
Note 1 : if a higher ring voltage is
required, use a 24-0-24V transformer (eg, Farnell 150-076) for
the ring supply instead of one of the
specified 15-0-15V transformers.
MAY1992
59
+ 1 2 V • - - - - - - - - - - - - + - - - - - - - - -....- - - - - - - - . . - - - ~ - - - ,
RING
202
3.3V
PHONE 2
100k
15
R
.,.
+12V
16
D10
VR1
100k
IC4
4017
Q3
BC547
37
240VAC
":'
3300
63VW
14
+
1000l25VW+
T2
15V-0-15V
OR
24V-0-24V
D5
+12v----------
8
rO.c
1N4004
VIEWED FROM
BELOW
TELEPHONE INTERCOM
Fig.2: the final circuit uses optoisolators IC5 & IC6 to isolate the ring circuits
from the control logic. When one phone is taken off-hook, then either Ql or Q2
turns on to activate the ring relay in the other circuit. Transformer T2 provides
the ring signal, while IC4 & its associated parts generate the ring sequence.
AND gate ICZa, to pins 5 & 6 of NOR
gate IC3a, to pin 13 ofIC2c, and to pin
8 ofIC2d.
Assuming that both phones are initially idle (ie, on-hook), the output of
ICZa will also be high. This holds the
RS flipflop formed by IC3b & IC3c in
its reset state, with "Q" low & "Q-bar"
high. The Set input of the RS flipflop
60
SILICON CHIP
(pin 13 of IC3c) is fed from pin 4 of
IC3a which is currently at logic 0.
If phone 1 is taken off-hook, current flows through the LED in optoisolator IC5 and turns on the internal
transistor. This pulls pin 1 of ICla
low and thus the previous high on the
reset of the flipflop is also toggled low
(via IClb & ICZa), which means that
the flipflop can now be toggled.
Similarly, if phone 2 is taken offhook, pin 3 of IClc goes low and
toggle~ the Reset of the flipflop low
via ICld & ICZa.
IC3d detects any difference between
the states of the two phones. When a
difference is detected (ie, when one
phone is taken off-hook), its output at
pin 3 goes high and turns on LED 1
via transistor Q5 (actually, ICZa, IC3a
& IC3d together form an XOR gate to
detect the different phone states).
TABLE 1
Symptom
Possible Fault
No sidetone in
either phone
Is green "power-on" LED lit? Check all voltages. If either + 12V or
+46V rail missing, switch off & di$COnnect the logic PC board
from the supply. Power up & check the supply rails again. If
supply rail(s) still missing, check the supply board; if supply rai ls
now correct, check for a snort on the logic board.
No sidetone in
one phone only
(1 ). Check that the associated 220-ohm protection resistor in the
loop circuit has not burnt out.
(2) . Do cabling & telephone test OK? Check by swapping phone
lines over on the back of the interface. If the same phone still
has no sidetone, then the fault is either in the phone itself or in
the cable.
No ring to
either phone
(1 ). Check that the 220-ohm ring protect resistor (connected to
transformer T2) has not burnt out due to excessive current.
Check the loop circuitry carefully before replacing this resistor.
(2). Are interrupted ring counter IC4 & transistor 03 operating?
Test by earthing collector of 03.
(3). Check that the orange LED (LED 2) is off when both phones
are on-hook. If LED is on & logic circuitry is OK, then one phone
is faulty or there is a cabling fault. Test this by removing the
wires from the interface.
No ring to one
phone
(1 ). Check ring supply voltage from transformer T2.
(2) . Is associated ring relay (RLY1 or RLY2) operating? If phone
1 does not ring, check for high on pin 11 of IC2c. If pin 11 high,
suspect switching transistor 01 & RLY1. If phone 2 does not
ring, check for high on pin 1O of IC2d. If pin 1O high, suspect 02
& RLY2.
In addition, when IC3d's output
goes high, pin 3 of IC2b also goes
high. Depending on which phone was
taken off-hook, then pin 11 of IC2c or
pin 10 ofIC2d will switch high. (Note:
IC2 is a 4081 quad 2-input AND gate.
When both inputs of these AND gates
are high, the gate output will be high).
Let's assume that phone 1 has been
taken off-hook. In this case, pin 10
of IC2d switches high and forward
biases Q2. Q2 then subsequently turns
on and activates ring relay RLY2 whenever Q3 in the ring circuit turns on.
Similarly, if phone 2 is taken offhook first , pin 11 of IC2c switches
high and forward biases Ql.
In other words, taking phone 1 offhook closes RLY2 and rings the bell
on the other phone. And vice versa.
the beginning the ringing cycle, rather
than having to wait for possibly up to
two seconds for the ringing cycle to
begin.
IC4 is clocked by Schmitt oscillator
stage IClf and turns on Q3 and ring
relay RLY2 each time its "1" and "3"
outputs go high. It also switches interrupt transistor Q3 (via its "2" output) to generate the required ring cadence. The exact operation of the ring
cadence generator is described a little
further on.
Each time RLY2 operates, its contacts close and the AC ring signal
from transformer T2 flows through
phone 2, ZD2, the series 1.2kQ and
220Q resistors, and the 3300µF filter
capacitor on the +48V supply rail.
If the calling phone now goes back
on-hook, pin 3 ofIC3d goes low again
Ring circuit
and the circuit reverts to the idle conCounter stage IC4 (4017) and its · dition. Alternatively, if the called party
associated parts form the ring timer answers, pin 4 of IC3a goes high and
circuit. It is normally held reset by toggles the flipflop (IC3b & IC3c). This
ICle but is activated when pin 3 of sets Q-bar of the flipflop (pin 11 of
IC2b goes high and pin 8 of ICle IC3c) low, which in turn switches pin
switches low. This ensures that the 3 of IC2b low and stops the ring.
Conversation can now proceed,
counter is only one "clock tick" off
g
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2764 ............. $6.50
27C64 .......... . $7.00
27128 .... .. .. .. . $7.50
27C128 ......... $8.00
27256 ........... $8.50
27C256 .. .. ..... $9.00
27512 ......... $12.50
27C512 .... .. . $13.50
27C1001 ... .. $23.50
RAMS
6116 .... .. ....... $4.50
6264 ........ ..... $9.50
62256 .... .... . $17.50
628128 ...... . $60.00
SERIALPOFIT
CHIPS
8250 .. .... ... ... . $7.50
82450 .. ....... $17.50
16C450 ....... $18.00
16C550 .. .. ... $29.50
***************
~
~
~-~ - n r
PRIMES~ S
DYNAMIC RAMS
4164-10 ........... $3.25
41464-08 ... ... ... $2.75
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7905T .............. $0.60
7912T ...... ........ $0.60
7915T .............. $0.60
317T ................ $1.50
337T ................ $2.10
723 .................. $0.80
DIDDEI
IN4148 .......... .. $0.04
IN914 ......... ..... $0.05
IN4004 .......... .. $0.08
IN4007 ............ $0.10
IN5404 ............ $0.20
IN5408 ............ $0.25
TIIMIISTORS
BC547/8/9 ........
BC557/8/9 ........
B01 39 ..............
B0140 ..............
TIP31C .... .........
TIP32C .............
MJ15003 .........
MJ15004 .........
MJ2955 ...........
2N3055 ............
$0.15
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LINEAR l
SPECIAL FUNCTION
1488 ................ $0.50
1489 ................ $0.50
8250 ......... ....... $7.50
82C450 .......... $17.50
16C450 .......... $18.00
16C550 .......... $29.50
XR2206 ............ $8.50
ICL7106 ......... $14.00
324 .................. $0.75
339 .................. $0.50
358 .................. $0.90
555 .. ................ $0.45
741 .................. $0.55
IRIDOES
W04 ........... .....
BR64 ...... .........
BR104 .............
BR254 .............
BR354 .............
LEDS
5mm RED ........
5mm Green .....
5mm Yellow ....
$0.50
$1.50
$2.50
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FREE PRICE LIST
UPON REQUEST
$0.15
$0.25
$0.25
ELECTRONICS & COMPUTER SUPPLIERS
289 LATROBE ST
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PHONE: (03) 602 3499 FAX: (03) 670 6006
MAIL ORDER HOTLINE: (008) 33 5901
ALL MAJOR CREDIT CARDS WELCOME
POSTAGE RATES
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$50.00-$99.99 .... $5.50
$100.00-$199.00 $6.00
$200.00+ ............. FREE
M AY1992
61
CORD GRW
GROMMET
PHONE 1
PHONE 2
REAR PANEL
ACTIVE
(BROWN)
NEUTRAL
(BLUE)
•
•
•
240VAC
T1
•
•
•
01000uF
•
•
•
T2
•
,.
G• 7812
e+46V
O•
•
•
FRONT PANEL
Fig.3: this diagram shows how the parts are installed on the PC boards. Note
that the two 1.2kQ 1W resistors on the logic board are soldered to PC stakes
(see text). The two boards are connected together using 4-way telephone cable.
with the audio signal coupled by the
600:600 ohm transformer (T3).
When one party subsequently replaces the handset, pin 3 of IC3d will
go high and attempt to ring the idle
phone. Ringing will not proceed, however, because the flipflop is set (Q-bar
low), thus depriving IC2b of the required logic high.
The flipflop remains set until both
handsets are replaced and IC2a resets
the logic to its standby state, ready for
another call attempt.
Ring sequence
The ring cadence can be easily customised to suit your applicmtion. Some
constructors may choose to build the
62
SILICON Cf:IIP
unit as close to the Australian standard as possible, whereas others may
opt for an" American-sounding" ring,
or some other sequence.
The standard ring cycle that we are
familiar with has the following pattern: 400ms on, zooms off, 400ms on,
2s off, and so on.
To generate this sequence, we would
normally require a zooms clock period and a counter with 15 outputs
(ie, we would have to use two counter
!Cs in cascade). Another way is to use
a single standard decade counter, the
4017, and addJogic to make it suit the
application.
In this circuit, the 4017 (IC4) is fed
from a 2.5Hz clock (IClf) which pro-
vides a period of 400ms per step. However, as the output corresponding to
the zooms "off" period goes high (output "2", pin 4), the clock is doubled
in speed to give the required zooms
period.
This is easily accomplished using
PNP transistor Q4 and the lOµF capacitor wired between its emitter and
collector.
In operation, Q4 is normally conducting and the lOµF capacitor across
it is short circuited. However, when
output "2" (pin 4) of IC4 goes high, it
turns off Q4 and this switches the
lOµF capacitor in series with an existing lOµF capacitor in the clock's timing circuit . .
Because the two capacitors are in
series and of the same value, the total
capacitance seen by IClf is now
halved. The clock therefore doubles
its frequency, giving one zooms burst
to step the counter past output "2".
When output "3" goes high, Q4 turns
back on again and the clock reverts to
its 400ms period.
Diode DB resets the counter when
output "9" (pin 11) goes high to limit
the off period to 2s following the second 400ms ring. The ring sequence is
then repeated.
Although Fig.2 shows the circuit
arrangement for the Australian ring
standard, you can easily customise
the ring to suit your own requirements. For example, the clock frequency can be adjusted over a wide
The two PC boards are housed in a ·
metal case & secured on 5mm spacers
using machine screws & nuts. The
screw terminals on the rear panel
provide the connections for the lines
to each telephone.
range using VR1, or the ringing sequence can be changed by using different counter outputs.
If you don't require the standard
"ring-ring" cadence, omit Q4 and replace the lOµF capacitor between its
emitter and collector with a wire link.
check the circuit boards for undrilled
holes and damaged tracks. In particular, check the logic board around ICZ
& IC3, since the tracks here are very
fine. Check also that the mounting
holes and the holes for the transformers, filter capacitor, relays, PC stakes
and trimpot are large enough.
Fig.3 shows the wiring details. Begin by installing PC stakes at all exter-
Construction
Construction is straightforward,
with most of the parts accommodated
on two PC boards. One board (code
SC12105921) carries all the logic circuitry, while the second board (code
SC12105922) carries the power supply components.
Before mounting any of the parts,
TABLE 1: RESISTOR COLOUR CODES
0
0
0
0
0
0
0
0
No.
3
2
6
2
2
3
2
Value
4-Band Code (1%)
5-Band Code (1%)
100kQ
47kQ
10kQ
1.2kQ
680Q
2200
150Q
brown black yellow brown
yellow violet orange brown
brown black orange brown
brown red red brown
blue grey brown brown
red red brown brown
brown green brown brown
brown black black orange brown
yellow violet black red brown
brown black black red brown
brown red black brown brown
blue grey black black brown
red red black black brown
green black black brown
MAY
1992
63
0
-
( \J
(]\
--
If)
C)
( \J
u
(I)
0
0
0
0
0
(\J
(\J
(J\
If)
0
-( \J
u
(I)
0
0
Fig.4: here are the full-size patterns for the two PC boards.
64
SILICON CHIP
nal wiring points on the power supply board,
then fit the 7812 voltage regulator, capacitors and transformers. Take care with the
orientation of the voltage regulator - see
Fig.2 for the pin connection details.
Moving now to the logic board, install the
five wire links before mounting any of the
other parts (one link runs underneath two
ICs). Once these are in, fit PC stakes to the
external wiring points and install the remaining parts as shown, leaving the relays
and transformer until last.
Note that you should also fit PG stakes at
the mounting points for the two 1.2kQ current limiting resistors (in series with ZD1 &
ZD2), since these values may have to be
adjusted when the circuit is operational.
The prototype was housed in a metal case
measuring 256 x 76 x 155mm and fitted
with an adhesive aluminium label. After
attaching the label, drill mounting holes in
the front panel for the two LEDs, then drill
the rear panel to accept the mains cordgrip
grommet, an earth lug mounting screw and
the screw terminals for the telephone lines.
The two PC boards can be used as templates to mark out their mounting holes on
the bottom of the case. Once the holes have
been drilled, secure the mains cord to the
case using the cordgrip grommet and solder
the Active (brown) and Neutral (blue) leads
to the power supply board.
The Earth lead (green/yellow) is connected to the earth lug on the rear panel.
This lead should be made longer than the
Active and Neutral leads, so that it will be
the last to break if the cordgrip grommet
comes adrift.
Once the mains wiring has been completed, mount the two boards in the case on
5mm standoffs and secure them using
screws, nuts and star washers. The remainder of the wiring can now be completed as
shown in Fig.3. This includes a 4-wire connection between the two boards, plus wiring from the logic board to the front and rear
panels.
Testing
Before applying power, go over the project
carefully and check for wiring errors. In
particular, check that all parts are correctly
oriented and that the mains cord is securely
held by the cordgrip grommet.
When you are satisfied that everything is
correct, switch on and check the supply
voltages. The output of the 7812 regulator
should be at +12V, as should pin 14 ofIC1,
IC2 and IC3, and pin 16 of IC4. The positive
terminal of the 3300µF filter capacitor
should be at about +46V.
Exercise caution when making these
measurements, as mains voltages are present
tended life for carbon granule type
transmitters. The level of sidetone (ie,
the level at which you hear your own
voice) is also be reduced.
Of the phones tested, many gave
reliable communication with as little
as lOmA of loop current, although
one Siemens model would not send
DTMF tones from its keypad until it
. had about 25mA flowing.
Fault finding
The two 1.2kQ lW loop current limiting resistors may have to be reduced in
value for telephone lines of considerable length. Generally, you should aim for
loop currents of 10-25mA. You can check this current by connecting your
multimeter across each telephone while it is on-hook.
on the underside of the power supply
board.
Assuming that the supply voitages
check out, short pins 4 and 5 of one of
the optoisolators (IC5 or IC6). One of
ring relays should now begin operating, according to the programmed ring
sequence.
Trimpot VR1 can now be adjusted
to give the correct clock period. If you
want to simulate the Australian ring
standard, just adjust VRl so that each
complete ring cycle lasts three seconds (ie, 400ms on, zooms off, 400ms
on, Zs off). Alternatively, you can connect the two telephones to the circuit,
take one of them off-hook, and adjust
Fig.5 (below): this full-size artwork
can be used as a drilling template for
the front panel.
VR1 until you get the correct "sound".
Installation
The values of the current limiting
resistors in series with ZD1 and ZDZ
may have to be adjusted according to
the lengths of the individual lines.
Generally, a loop current of 30mA
should be considered the maximum.
For most in-house or house-togarage use, 1.ZkQ 1W resistors (as
shown on Fig.2) will do the job. However, lines of considerable length require lower value resistors because
the resistance of the cable itself provides a certain amount of current limiting.
If built solely for use as an intercom, the loop current can possibly be
reduced to as low as 10mA. The benefits of lower loop current include
longer operating distances and ex-
If you strike problems, first check
that all ICs have+ 12V on their supply
pins. You should also check the boards
for missed solder joints and for solder
shorts between adjacent IC pins (make
sure that the power is off).
Next, trace through the gates with a
logic probe or a digital voltmeter to
check that the input logic is operating
correctly. Check that pin 12 of IClb,
pin 10 of ICld and pin 4 of ICZ are all
high when both phones are on-hook.
Pin 4 ofICZa should switch low when
one phone is taken off-hook.
If you don't get the correct readings
here, check the optoisolators and the
input buffering circuitry (IC1a-IC1d).
Table 1 lists a number of possible
symptoms and their likely causes. By
following this table carefully, you
should have little difficulty in tracking down any likely faults.
References
(1). Telephony, Volumes 1-5. Postmaster-General's Department, Australia.
(2). Telephony and Telegraphy. Sydney F. Smith. Oxford University Press.
Caution
This intercom must not be connected to Telecom lines. It is intended only for use on lines completely separate from Telecom installations.
TELEPHONE INTERCOM
0
0
POWER
CALLING
MAY 1992
65
ROLEC
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ROLAUS
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CONSUMER ELECTRONICS
2M213
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Microwave Ovens
These capacitors are used in vo ltag e doubler circuits in
high vo ltage microwav e oven transformers. In these
applications, the capac itor must be capab le of
withstanding an AC voltage equal to twice the peak
voltage of the transformer output voltage .
Oolll••·•c
... •
170-HOOYAC
N50H1770G
N50H2170G
N50H2 570G
N50H 1775G
N50H2175G
N50H2575G
NSOH I 780G
NSOH21 BOG
Ns0 H2s80G
N50H1785G
NSOH1785G
N50H2585G
N50H1790G
NSOH2190G
N50 H2590G
N50H1795G
NSOH2195G
N50H259SG
NSOH1710G
NSOH1710G
N!!iOH2 51 0 G
NSOH17 10G
NSOH 2 110G
NSOH1711G
NSO H2111G
N!!iOH1712G
NSOH2112G
0 .70
0 .70
0 .70
0 .75
1700
2 100
2 500
1700
0 .75
0 .80
0 .80
2500
1700
2 100
2500
1700
2100
2500
1700
2100
2500
1700
2 100
2S00
1700
2100
2500
1700
2 100
1700
21 00
1700
2100
o.eo
0 .85
0.85
0.85
0 .90
0 .90
0 .90
0 .95
0 .95
0.95
1.00
1.00
1.00
I.OS
1.05
1.1 0
1. 10
1 .20
1.20
A
A
A
A
.A
A
A
A
A
A
A
A
A
1.25
1.25
1.25
1.25
1.25
1 25
1 25
1.25
1.25
1 2s
1.25
1.25
1 25
1.25
1.~5
1.25
1.25
1.25
1.25
1.25
1 .25
1 .21!1
1.21!1
1.25
1 .25
1.25
1 .2 5
2.so
3.31
3 .75
2 .50
4. 25
2.50
3.31
4.25
3 .oo
3.31
4 .25
3 .00
3 .31
4.75
3.00
3 .31
4 . 75
3.00
3.31
4 .75
3.00
4 .00
3 .00
4 .00
3.13
4.00
e 3 .5
84 .0
95 .3
63. 5
84.0
108.0
63.5
84 .0
108 .0
1e .2
84 .0
108.0
7 6 .2
84 .0
120. 7
76.2
84.0
120.7
7 6 .2
8 4.0
120.7
76.2
101 .6
76.2
10 1.8
79.S
101.6
Typlc•I 8 1lH for ou,1 C•p•cll,nc• A•Ung,
N84H2295G 0 .67 + 0 .28 2200
1.75
2.56
0 .33 2200
1.75
2 .56
68
N64H2512G 0.90 + 0 .48 2500
1.75
4.06
102
N64H2210G 0 .70
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A full range of products available on request
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VINTAGE RADIO
By JOHN HILL
Aligning vintage radio receivers, Pt.2
Last month's Vintage Radio column covered the
various components involved in receiver
alignment. We now move on to the equipment
used for alignment and describe how it is used.
It is both easier and quicker to align
a superhet receiver if you have the
right equipment. The right equipment
in this case is a radio frequency (signal) generator and an output meter.
However, as these instruments are not
always available, we will also describe
the alignment procedure without
them.
Signal generators
A signal generator does exactly what
its name implies - it generates RF
signals which can be injected into a
radio receiver at various points. It is
usual to modulate the RF signal with
an audible frequency of around 400-
lO00Hz, so that the signal can be heard
in the receiver's loudspeaker. Signal
generators are tunable and any desired frequency can be obtained simply by selecting a frequency range
and setting a calibrated dial.
Modulating the RF signal with an
audible tone is similar to what happens at a radio station's transmitter,
where the radio frequency signal (carrier) is modulated by audio frequencies (speech, music, etc). A simple
way oflooking at this is to think of the
RF signal as the vehicle and the audio
frequency signal as the passenger. The
receiver is designed to receive, amplify and separate the two signals, for
An RF (signal) generator and an output meter make the task of receiver
alignment much easier. This photo shows a Heathkit RF signal generator and
a standard multimeter.
68
S ILICON CHTP
it is only the passenger that is of interest in the end.
Likewise with the signal generator.
It is of little use injecting a radio frequency signal into a receiver if we
cannot monitor it. If we modulate the
RF signal with an audio signal, we
can both hear it and see its strength
on an output meter.
The main advantage of using a signal generator is that it supplies a constant and stable signal at any chosen
frequency. Also, its amplitude can be
varied as appropriate during the various alignment stages, thus making it
more convenient to use than a distant
radio station.
Output meter
An output meter is used to measure
the output signal strength of the receiver being aligned. Its two leads are
usually connected to the anode of the
output valve and to the chassis. In
some cases, it can be connected across
the loudspeaker's voice coil but this
method is not successful unless the
meter is particularly sensitive.
Some multimeters have a special
output socket (to accept the lead connected to the output valve anode) but,
unfortunately, many lack this refinement, which makes things a little more
difficult. However, any multimeter
with an AC volts range can be easily
adapted for use as an output meter.
To explain, not all voltages are pure
AC or DC - some can be a mixture of
both. In the case of an output valve,
the AC audio signal which drives the
loudspeaker is superimposed on a DC
voltage of about 250V which is applied to the valve's anode. An output
meter is designed to ignore this DC
voltage and display the AC (audio)
component only.
This seemingly difficult task is easily accomplished by placing a high
instantaneous level of the voice or
music signal being received.
On the other hand, if using a signal
generator, the meter needle will remain steady because the audio signal
is constant. Under these conditions,
it is very easy to align a receiver for
maximum needle deflection on an
output meter.
Alignment tools
IF transformers are adjusted by one of two means - either by using trimmer
capacitors, as shown at right, or by adjustable iron slugs (left). Some early
transformers may only have one adjustment instead of the usual two.
voltage capacitor (of about .047µF, or
larger) in series with one of the meter
leads. This capacitor blocks the DC
voltage but allows the AC voltage to
register on the meter.
Therefore, any multimeter with AC
ranges can be used as an output meter
by making up a special lead with a
suitable capacitor in series with it.
Such a lead requires a small insulated
alligator clip at one end and a banana
plug or whatever to suit the meter
socket at the other end. The capacitor
connections must be well insulated.
If you have a multimeter with an
output socket, the blocking capacitor
is already built into the meter. However, it is advisable to check this capacitor. Either check the circuit for
specification or open the back of the
multimeter and have a look. The capacitor must have at least a 400V rating and should ideally be a modern
plastic type if it is to be used on valve
receivers.
I speak from experience. The only
meter I have with an output socket
has already blown its original 400V
capacitor and now has a 630V replacement. Perhaps the capacitor was
faulty but it sure did burn out. Correction: it blew out - paw!
If you don't have a signal generator,
then there is little point in using an
output meter in the manner described
above. When using radio stations as a
signal source, an output meter will
flicker up and down according to the
This multimeter has an output socket with a high-voltage
capacitor in series with the meter circuit to block any DC
components. It can thus be used to monitor the output
signal level by connecting it directly to the anode of the
output valve. Not all multimeters have this function.
The tools used for alignment adjustments are confined (in most instances) to insulated screwdriver
blades. However, the everyday screwdriver is not the best tool to use. Simply touching a metallic screwdriver
blade onto some alignment components will change the alignment. And
in some cases, it can cause -:1 high
tension short circuit or give Lie operator an electric shock.
The recommended tool in the old
days was a non-metallic screwdriver
fashioned from a toothbrush handle
or similar insulating material. Such a
tool is quite satisfactory provided it
will turn the adjustment screw.
Unfortunately, plastic screwdriver
blades are a bit gutless when it comes
to torsional strength. If the adjustment screw shows any degree of resistance, then the blade simply snaps
off. In addition, many modern insulated alignment tools are moulded
from a flexible plastic material which
is often inadequate for valve radio
applications.
I recently made a couple of alignment tools from 6mm-diameter acrylic
rod. Into the ends of these rods are
cemented very short metal screwdriver blades which have been spe-
An AC voltmeter can be used as an output meter simply
by fitting a .047µF 400V capacitor in series with one of its
test leads. The capacitor blocks the DC voltage on the
anode of the output valve but allows AC signal voltages to
register on the meter.
MAY 1992
69
TABLE 1
Variations in intermediate frequencies as taken from the 1938 Australian Radio Service Manual
kHz
kHz
kHz
175
392
180
450
452.5
455
456
457.5
458
468
462.5
465
470
472
182
250
252
252.5
455kHz is by far the most common IF for valve radios. However, many early
superhets had odd frequencies, with 175kHz being quite common in the 1930s.
When aligning the IF transformers on a superhet, the generator signal is
jnjected into the circuit via the grid of the frequency converter valve. If the
valve does not have a top cap, a connection on the appropriate fixed plates of
the tuning gang will do the job just as well (see text).
cially made in various sizes from high
carbon steel. These alignment tools
give the best of both worlds in that
they are reasonably strong and the
small metal tip has little or no affect
on the alignment setting.
In some cases, however, the alignment components are so stiff that they
can only be turned with a standard
screwdriver. This is of no great concern provided the tool is used properly.
First, the blade needs to be fully
insulated to within one millimetre of
the tip, to prevent short circuits and
possible electric shock. This can be
70
SILICON CHIP
done using insulation tape or a piece
of heatshrink tubing of appropriate
size and length.
Second, after each adjustment, the
metal screwdriver must be removed
from the screw slot so that the output
meter can display the true reading.
Alignment may be a bit slow and tedious by this method but sometimes
there is no alternative. If the adjustment ~crews are tight, then a metal
blade is the only way to move them.
Alignment procedure
The correct starting point for
superhet alignment is at the interme-
diate frequency (IF) transformers. The
first step is to connect the RF generator leads to the grid of the frequency
converter valve and to chassis.
If you have trouble working out
where the grid is on the converter
valve, it is usually the top cap that
connects to one of the tuning capacitor gangs. If the valve has no top cap
grid connection, trace the wiring to
determine which tuning gang section
connects directly to the converter
valve and connect the generator lead
to the fixed plates of that particular
section (or to the corresponding valve
socket connection).
It is important to inject the correct
frequency into the receiver in order to
tweak up the IF transformers. Today,
the industry standard IF is 455kHz
and this frequency has been established long enough for it to apply to
many valve receivers as well. However, some early superhets had quite
weird IFs, as a quick look at Table 1
will show. The set's IF transformers
should be tuned to the frequency that
they were supposed to operate on but
this frequency is not always known.
Now if a receiver with a 460kHz IF
is aligned to 455kHz, it will not prevent the receiver from working - although it will work better when
aligned to the correct frequency. In
particular, it may upset the dial calibrations slightly and/or the front-end
tracking. More on this later.
One way to ascertain an unknown
IF is to connect the signal generator to
the receiver and adjust the generator
dial until maximum signal is heard in
the loudspeaker. Provided that the IF
transformers have not been previously
tampered with, the generator dial
should indicate the receiver's IF.
Once the IF has been established,
the IF transformers can be adjusted
RESURRECTION
RADIO
Vintage Wireless Specialists
A metal-bladed screwdriver can be used as an alignment tool when the
adjustment screws are tight. This particular tool has an insulated blade with
only the tip exposed. Such a precaution is necessary when adjusting early IF
transformers to prevent short circuits and possible electric shocks.
for maximum output. This should be
done with the tuner plates completely
out of mesh, the volume control at
maximum and the signal generator
adjusted to feed in just enough signal
to activate the output meter.
AVC action
There is a very good reason for these
level settings and that is to effectively
disable the AVC (automatic volume
control) system. If the AVC is operating, it will try to counteract any increase in output signal due to improved alignment, thereby making the
improvement less obvious. Since most
AVC systems are (level) delayed, keeping the input level down renders them
inoperative. As sensitivity increases
with alignment, the input level from
the generator should be progressively
These two special alignment tools
were made using acrylic rod and
metal screwdriver tips. The small
steel tips were cemented into the ends
of the rods.
decreased, to keep the output approxi mately constant.
If an off-air signal must be used,
there is another way to set up an output meter, this time so that it monitors the AVC system. By using a
stronger (off-air) signal, the AVC system will be activated and, by monitoring this , we can measure the effect of
adjustments.
The AVC action can be monitored
by measuring the voltage developed
across the cathode bias resistor of the
IF amplifier (typically 3V). As alignment progresses, more AVCvoltage is
applied to the valve grid, less current
is drawn, and less cathode bias is
generated. So you simply adjust the
IF transformers for a dip in the meter
reading, rather than a peak.
Note, however, that the meter may
not respond to adjustments to the IF
secondary winding. The AVC voltage
is normally taken from the primary of
this transformer. But all earlier stages
(aerial, RF, oscillator and IF primary)
can be monitored.
When making these adjustments, it
matters little in what order they are
done provided that the trimmers or
cores are peaked a number of times.
Some adjustments will be sharper than
others.
At this stage the IF transformers are
aligned. The next step is to align the
aerial and oscillator circuits. This will
be covered in next month's Vintage
Radio.
SC
Repairs - Restoration - Sales
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MAY 1992
71
AL TRON/CS - SETTING NEW STANDARDS
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The Powerhouse has been designed not only for rugged bullet proof operation but for ease
of construction, two PCB's hold all circuitry with one inter-connecting cable. (7 wires).
Thi• kit comH to you In I fully drllled, pre punched ch111l1 complete with 1llk ■crHned
front panel. Auembly of the kit 11 1lmpllfled H the maJortty of component, mount on •
llngle PCB. Thul vlrtu■ lly ellmlnatlng 111 external terminal,. Suitable for UHi In camping,
boating, f11hlng, mining, remote Htllement1 etc.
Feature■ :• Massive 1200W continuous 2400W surge will run
almost anything• 12 or 24V operation selected via internal wiring
• Low battery cut-out • Over temp cutout • ·:iircuit breaker for
overload protection• Auto start circuitry for standby operation•
Easy to construct
Recharge Your Mobile Phone, or
Run Your Electric Shaver from
the Car Battery'
This fantastic little unit is ideal for use with
incandescent globes, (note this model
inverter will not run fluorescent lighting)
electric shavers, small radios and some plug
pack operated devices, ie charging cordless
drills and other rechargeatle battery
appliances etc.
Feelurea: • Operates off 12V DC • Battery
connection leads provided • Light weight •
Uses Mosfet devices • High efficiency • Low
heat dissapation
Baby Room Monitor
(S.C. Jan '91)
This TV transmitter
enables you to
transm it signals from
the output of your
VCR to a second TV
set in the house
without messy splitters .
and cableis. Two versions available for videos
with UHF or VHF outputs.
NEW
UHF Version
FOR
VHF Version
'92
K
K5860
5885
$74 .95
Digital Altimeter
for Gliders
and Ultralights
(SC Sep/Oct '91)
K 1180
$24.95
This Baby Room Monitor allows you to
listen to your baby from a remote
location using a conventional FM
receiver. It runs from a single 1.5V AA
battery and includes a muting facility
so that it only transmits sounds above
a certain level.
8
Using state of the art
circuitry this supply will be a
great asset to the enthusiast
and professional alike. It
uses switch mode principles
which allows for smaller
transformers, and
heatsinking which means
greater efficiency, less heat
and lighter weight.
Feature•: • Variable output • Variable current limit • Separate Earth Terminal •
Individual Volt and Amp Meters • Constant 13.BV setting • Short circuit proof
Sp ecifica tion ■: • Output voltage 0-45V • Output current BA <at> 35V, 6A <at> 40V •
Load regulation 1% • Ripple and Noise 40mVp-p at BA 35V • Current limit 800mAB.6A • Over current limit 9A • Foldback current less than 2A
(SC Jan '92)
NEW FOR '92
Build this simple little device, and avoid getting
caught out with a flat battery during your
holidays. It simply connects into a 12V
accessories power line, and shuts off the flow if
the battery voltage drops to a dangerously low
level. Ideal for battery powered camping fridges
etc. Adjustable Cutout Variable from 10.9V to
11.9V. Includes Automatic or Manual Voltage
Reset Function.
If::;_;. LOW VOCTAGE CUT-OUT
. __,,,,. __] ;----·~-::-~1
1-.~ (
,,,-, 01.,~'
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:__
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K4328 $24.95
Infra-Red Light Beam Relay
~~'"""~
---. .
_,~~
..
*
is compact digital altimeter
·
n display altitude up to 19,990 feet with 10 feet
solution. Accurate to better than 3.5 percent. A must for
'.:hts etc. Op:;:sF;R9~;-itery
Here's a simple
project that
monitors the power
drawn from a
'master' socket and
automatically
switches on a 'slave'
socket. It is
Activate all Your Hi-Fi
versatile, because it
by Turning on just the
can monitor one or
Amplifier!
several appliances
plugged into the 'master' and switch on one or several
devices plugged into the 'slave'. Ideal for Hi-Fi's or
computers with peripheral hardware.
K6070
$59.
95
Adjustable 0-45V, 8 Amp Bench Power
Supply (SC Jan/Feb '92) K3360 $375 .00 Massive Powe, C Pab1/ity,1
Low Voltage Cut-Out for Cars and Boats
NEW FOR '92
,·- ·""'~ -·: ·
:::1$2.99
K6790 Kit Version $799.oo
K6792
Built & Tested 12V Input $999
K
6793 Fully
Fully Built & Tested 24V Input
.00
(SC Dec '91)
This simple project allows you to
monitor a doorway or a path using
an infrared light beam. When
someone walks through the beam,
it triggers an alarm for a 1 second
period. Ideal door monitor for
shops or for security around home
or office. Requires 12V DC
plugback (M 9002).
NEW
K1920 $32.95
~~2R
J.
•••
GJ
-
'
4 Channel Guitar Mixer and
NEW
Preamp
FOR
K5535$49.95
(SC Jan 1992)
'92
This unit features separate bass, midrange and tre~le
controls, very low noise and distortion, separate input
level controls plus an output level control. Ideal for use
with most musical instruments from keyboards to guitars
to tape decks. In fact, you can feed it with just about any
audio signal - it's not just limited to guitar outputs.
• Dl1tortlon: (at 1kHz and 1OOmV input) less than 0.0075%
• Frequency ReaponH : 18Hz-35kHz (+/-3dB).
The kit includes PC Board, potentiometres, input sockets
and all specified components. The kit does not include
the optional ground plane, nor the 15V power supply
board.
Low Cost
'Karaoke'
Adaptor
(EA Nov '91)
It's time to bring out all those hidden vocal
talents that you've always known were there. With
this project you can remove the lead vocal from
almost any recording, and replace it with your
own via a standard microphone. It's a great way
to liven up a party!
Kmo $34.s5
(SC June/July '91)
Make your 1tage production a proteNlonal
lhow wtth 1h11 new Lighting Mixer. Ideal tor
amateur theatre groupe band1 etc.
his great new kit enables you to
U!ltomize your sound system In
ur car or at home. The circuit
mply connects between the audi
urce and the amplifiers. There
re two outputs, one for bass
nd another provides signal for th
equency range (i.e. one for bass, one
This 4-channel lighting desk is intended for
theatre, disco and music group applications.
It has heavy duty circuitry and is able to cope
with spotlights rated up to 1000 watts or
more. It has been designed and built for the
rigours of commercial use . You can flash
each channel up to any brightness as set by
the 'Flash Master' fader. Similarly, the
'Channel Master' control fades all lights up or
down, to or from their individual fade settings. Two chaser faders control the rate
and lamp brilliance when the unit is operated in chaser mode. Th e lights can be
flashed to full brilliance or to an intermediate setting as set by the 'Chaser Master'
fader.
K
assive crossover is required in the speaker one pe
n + and -15V rails. The resu lt is much better sound
5570 $19.95
Surround Sound
Decoder
K 5585 $3
5815 $329.oo
(E.A. Jan
'92)
, - - - - - - t Build this new surround sound processor and . ,'
envelope yourself with the stunning realism ·'
and dramatic sound impact available from
SOW Mosfet Module
surround-encoded videos or TV
50 Watts RMS into 8 Ohms. This great module
features moderate power output at low
harmonic distortion. Simple to build and
compact in size this unit makes a great
replacement module for your old Hi-Fi or buy
two and make your own stereo amplfier.
K 5115
transmissions. It can also enhance
conventional stereo, by providing a rear or
'ambiance' channel.
0-30V Power Supply
$49.95
Hi
Syste
(SC May '8
Stereo 50 + 50 Watt
Midi-Style Amplifier
Replace That Old Beaten Up Amp!
(SC Feb and March '92)
-'IHI
,-,:
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h
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Economy Alarm Panel
For Home, and Small Commercial PremlaH
This is a 3 zone alarm control panel designed for the
protection of homes and small cg_mmercial premises. It
employs the latest advanced electronic circuitry offering the
highest degree of quality and reliability. It will accept either
active or passive norma ll y open or normally closed sensors
making it both a versatile and effective protection system . 12V
battery charger inbuilt. See Altronics '92 catalogue for full
details.
s 5480 $139.oo
Flush/ Surface Mount Alarm Panel
This amazing new model features just about everything you could imagine!
Multifunction keyring remote control wi ll arm and disarm alarm (and activate
central locking if fitted), chirp the horn , turn on car headlights. panic and even
open the boot (if actuator fitted). One remote can control two alarms.
Other features include: Starter inhibit, valet mode, central locking interface, flashes
car indicators when tripped, auto reset plus much more!,
s 5230 t249.oo
5231 ;Teplacement Remote
S
Control
$48.50
DIRECT IMPORT PRICE
l
With stylish compact good looks this alarm blends
smoothly into any residential or office decor by either
fl ush mounting into the wall, or surface mount. 3
sectors include 24 hour panic/fire, perimeter and
internal which can be isolated enabling the alarm to
be armed at night with occupants inside whilst still
protecting entries. simple 4 digit access code tor
operation. See Altronics '92 catalogue for full details.
s 5490 $119 .oo
UHF Microprocessor Controlled Wireless Security System
Apart from the flawless operation of the system one of the great features is its application with rented or leased premises - let's face it, money spent on installing a wired
system in your home or office, factory, etc is irrevocably lost when you move on. With this system you simply take it with you. Ultra high-tech and push button operation
makes this unit a breeze to install and operate. Features 6 sectors plus 2 x 24 hour fire and tamper circuits. The S 5240 system includes main controller, 1 Passive Infra
Red Movement Detector, 1 window or door Reed switch, wired siren. power supply, back-up rechargeable battery. and a special personal remote. All sensors are radio
transmitters which means no wiring is neccessary (except for the plug pack and siren). The wh ole system is coded so it can not be interfe,ed with and can be changed
any time by the owner. Each individual sensor can be eas ily set to operate on any sector. The main controller utilizes latest EEPROM technology which means things like
selecting user on/off codes, isolating sectors are a breeze. Includes a myriad of other amazing features, too many to mention .
Wireless Remo.le Keypad
Call AL TRONICS today for a frH colour brouchure.
Complete 1yatem Includes:
1
: ~i;;r~ in~~i Red Detector/ Tran smitter
1 x Door/Window reed Switch/Transmitter
1
1
1
1
1
1
s
External Siren ·
2015
C
$15.95
x
x
x
x
x
Hand Held remote Control/Tran smitter
Horn Speaker - 10 watt/wired
240V AC adaptor
1.2Ah Back-up Battery
Set of batteries for all transmitters
5240 Complete System
Door/ Window
Only
$679 .OO
eed
Switch & Transmitter
S 5247 $72.95
s 5255 $135.oo
Interlocking Part,
Unique design allows units to be
D rawer, · 'dove-tailed'
together. Drawers
_ _ _ _ will not stick or seize. Single or
pouble drawers available.
· H 0235 Single $4.95 ea
T 1250 $ 4 5 .oo
This lightwe ight de-soldering iron allows
components to be quickly and cleanly removed
with one hand. Naturally it's SEC approved and
comes with a cleaning wand. Can be used as a
soldering iron. 240VAC 30W. Earthed.
Simple cleaning
,, action.
H 0238 Double $5.so ea
Box
T 1255 Replacement 1.5mm Tip $4.95
J 1252 Replacement 1.2mm Tip $4.95
All New IRODA Gas Soldering Iron
Temperature
Adjustable Soldering
Iron
A/B Computer
Switch
~
:
·:: ····•,•-:, ,·,:.- ..-:,_:_:,:,::.:,:::::·:
"trodo:
Winner of the Taiwan Good Deolgn Award
Now you can solder anywhere with this new gas soldering iron.
Screwdriver temperature adjustable
between 2500C and 450°C enabling very
delicate soldering on low settings with
surprising heat energy reserve on
maximum setting. Relative temperature is
indicated by LED iamp brightness. Now
Two way printer/peripheral computer
switch with D25 sockets. Allows two
printers to be run off one computer and
individually selected or allows one printer
to be run off two computers and
individually selected.
D 1570 Normally
$;,8'95
Feature• • See through gas chamber (no more guessing how much gas is
left!) • Built in ignition cap• Uses standard butane gas• Comes with safety
bench stand • Supplied with 2mm soldering tip and blow torch tip •
Adjustable temperature from 400°C to 12000C • Can be easily refilled with
standard butane lighter gas • Replacement tips are less than half price of
some other brands!
REPLACEMENT TIPS - ALL $4.95 ea IT 2455 Replacement Exhaust Port
T 2451 Replacement 1mm Conical Tip T 2456 Hot Knife Tip
T 2452 Replacement 2mm Conical Tip T 2457 Hot Blower Tip
T 2453 Replacement 3mm Conical Tip T 2458 Blow Torch Tip
T 2454 Replacement 3mm Chisel Tip
T 2448 Weller Butane Gas Refill $5.95
u1ea 1tate ot the art ceramic heating
element. T 2448 Normally $ ~ 5
NEW
FOR
'92
This Month $ 3 9 .95
This Month $ 3 9 .95
Universal Remote
Control
This universal infra-red
remote control makes all
other remote units
superfluous. Will control
CD players, videos, TV's
and stereos etc. Controls
up to 6 different
appliances. Easy to use
and programme from an
existing functional remote.
I
Electronic Temperature Controlled ,
Temperature Selectable, Soldering
Station. The MICRON T 2440 solderin g
station offers the ultimate in controlled
temperature hand soldering.
Featureo: • Variable Temperature Control
• LED Temperature Readout • Zero
Voltage Switching protects CMOS
Devices • Grounded Tip • 48 Watt
Element • Thermocouple lmbedded in Heating Element for Precise
Temperature Control • 24V Low Voltage Element • Rubber Silicon Lead •
Chrome Plated, Iron Clad Ultra Long Lile Tips • New Improved Ceramic
Element
$139
T 2440 Normally $ % 5 , This Month Onl y
.95
With this simple device you can monitor
any door in your house. This two piece
alarm consists of control box and
magnet. The magnet simply mounts onto ·
the door frame while the unit is mounted
on the door so that when closed, the
magnet and control box are opposite.
Easy to use on/off switch. Built in
beeping buzzer sounds when tripped.
Requires 9V battery.
S 5315
A 1000 $69.a5
Micron Mk II
Soldering Station
Scoop Purchase On
Door Alarms
$15
G pR1cEl
p.l,,1Az1N
n,1, la the 1992 model of our fantutlc ubt.ch Duel Tree• 20 Meg Scope, There are over 3000 now In ••rtlc• throughout
Aullra//e - Our cu,tomer, Include Unlveraltte,, R••••rch Eatabllahment, and lndu■ try
SENSATIONAL VALUE
Famous Labtech 20MHz Dual Trace
NORMALLY $699
Oscilloscope
·~~- THAT's $100 OFF/
The '92 model is a dual trace 20MHz oscilloscope using a
high brightness CRT. The vertical amplifiers have high
sensitivity of SmV/ div and a frequency characteristic
response with smooth roll off exceeding 20MHz. The TV
sync. signal operator 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. Highly recommended for
Thl1 fantaotlc tuner 11 the Ideal add-on to any
aound 1y1tem. Can be u,ed a, background
mualc aource In reatauranta, ahop1 etc or any
PA appllc~tlon. Al10 a great upgrade for the
home HI-FI.
Featureo:
Q 0158 This Month Only $599.oo
~~'"-.-.------------------------------4
0 0175 $49.95 ea
Illuminated SPST
Rocker Switches
Amazing value! 24.ov AC inbuilt neon
glows red. Panel cutout 18.6 x 13mm.
s 3218 $1 .50
ea, or 10up $1
Pocket Sized,
Signal Generator
'B ;J
, -,
TURN 12V DC
TO 240V AC.
This fantastic
inverter will power lights, TV's, tools, electric
shavers and a whole host of other appliances.
Great tor camping, out in the bush and any
plac11 where 240V is not available.
Fe ■ ture,: • Complete with over current
circuit breaker• Fused 240V output• Built in
. panel meter to monitor output voltage •
Strong steel case and chassis.
Replace that old Dial Tuner!
1.\:.1'
Sarvlce Workbench, Deolgn Laboratory, Manufacturer,,
Unlver1ltle1 and the dedicated enthullaotlc.
Ideally suited to Q 0156 (2
required). Superb quality.
DC to 80 MHz. Max 600
Volts DC. Lead length
approx 1.Sm.
AM/FM PLL Tuner
This pocket sized oscillator
has all the features of a large Ii ~~I
bench oscillator. 46 preset
{
,..'-"''
.1
switched frequencies ranged / 1 · ~.- - ...... •• • -- -- ~ '
from 20Hz to 150kHz, eg:
a,
..,
1kHz, 1.2kHz, 1.5kHz,
• "'....-~)"{• ~
1.8kHz, 2kHz etc. Smaller
/,:"• 'I' '' ,•.
than most multimeters, this I ;;·
•
·,_.
is ideal for technicians,
! ::;
servicemen, students and
\·· -...._ ·
~ •..
hobbyists who require an
acc~rate and reliable
oscrllator ready to use
...~
:..;!"' r~
anywhere
I
M"''
I ;.:
'":f",. ,.,·•2~
I -~~.~-l:'J-im:c'j
J
Q 1542 Normally ~ o
·
This Mdnth Only $ 8 0 ,oo
G!!:~i!'..i:.::.
,x
CS
ea
• Digital LED frequency readout display
• FET FM front end for high image rejection
• Phase-linear ceramic filters are
incorporated in both AM and FM IF section
• Phase-lock loop (PLL) IC for FM multiplex
stage
• Dimensions: (W x H x D) 435 x 60 x 232mm
• Weight: 3kgs.
A 2210 Normally ~ . 0 0 ,
This Month $199.oo
Our Top Selling 17 Range Digital
Multimeter for
an Amazing $39.95
With quality and features you would expect only
on expensive meters the Q 1056 represents
excellent value for money.
Specification,:
DC Voltage: Ranges 2-2000V
AC Voltage: Ranges 200V, 500V
DC Current: Ranges 200mA, to 10A
Reol1tance: 5 Ranges 200 Ohm , to 2M Ohm
Diode Teot: Test Current 1.0mA
Test Voltage 3.2V Max
Battery Te,t: Ranges 1.5V, 9V
Loaded Current: 1.SV 100mA, 9V 6mA
Q 1056 Normally ~ 9 5
This Month $39.s5
Q 1057 Carry Case to Suit $1 2.50
Cleane
• High performance noise attenuating WtlY Pav $tf°
earphones • Noise cancelling
or More· · , ~
microphone• Cushioned head pad •
'-\'
,
Super sturdy • Great performance •
~
I
Awarded the
Good Product
D esign A w ard for
Superb, professipnal pilot's headset will -
CETDC in 1987.
last a lifetime with reasonable treatment
T his fantast ic
New model just arrived! 80 x 80 x
25mm. Ideal for amps, power
supplies, computers and just
about anything else that requires
effective cooling. Exceptional
value for money.
F 1050 $17.so
High Performance
Crossovers
',
Crossover Frequency: 3.5kHz
dB/Octave: 6dB
*
c 4005 $11.95
2 Way, 150 Watts RMS
Crossover Frequency: 3.5kHz
dB/Octave: 12dB
C 4007 $ 2 6 .95
3 Way, 80 Watts RMS
Crossover Frequency: 600-800Hz/5kHz
dB/ Octave: 6dB
c 400& $20.e5
3 Way, 150 Watts RMS
Crossover Frequency: 600-800Hz/5kHz
dB/Octave: 12dB
C 4008 $ 4
9 .95
'
I
standard button mounting.
r:di~ae~f~~i~i~~[s ~r~~·
0
~~!~~u~
Car Voltag e
Adaptor
Stereo Headphones
with Dynamic
Mic
Glasses, Watches
wire connection.
',
Fantastic new model includes
,
:t
·r.r
improved microphone and shielded
',
C
$27.
0335
95
cable, allowing even better
"'
<o
performance! Now better. value for
~-------------many than before. Over 2000
$189
already sold Australia wide.
C 9070 .
.00
.
etc.
2 Way, 80 Watts RMS
New stylist model, with simple
one handed operation. Uses
Complete with approx 1.5m
• Includes standard aircraft jacks.
Ultrasonic
Cleaner can earn
its cost a
hundred times
over in cleaning
Computer
Connectors,
PCB's, Switches,
Relays,
Jewellery,
These models
consist of
only high
quality
components.
PCB mounted
quick
connectors for
easy and reliable
If,
Noise Cancelling
CB Type Mlc
Simply brill iant Mylar stereo
headsets and dynamic mic
combination.
Speaker Speclflcatlona: 20Hz20,000Hz, 32 Ohm , 3.5mm
stereo jack , 6.35mm stereo
jack adaptor.
Microphone Spece: Dynamic
type, 300 Ohm, 100 Hz15,000Hz -80db <at> 1 Khz,
3.5mm Mono Jack
M 8150 $ 1 6 .e5
Portable PIR Alarm
c 9055
Entertainers Cardioid
Microphone
*
Professional Performance and Appearance. Balanced
mic with unbalanced canon to 6.5mm lead . Includes
vinyl carry case and mic holder.
Polar pattern: Cardiod
Impedance:
600 50-15,000Hz
Ohm
Freq.
re1pon1e:
Sen1ltlvlty: -75 +/ -3dB
Diaphragm material: Polyester film
This handy unit simply plugs into your
e
lighter socket and presto! Gives you switc~able 3, 4.5, 6,
7.5, 9 and 12V DC at up to 800mA. Includes a range of
output plugs. Reversable polarity. Great for pocket TV's,
radios, portable CDs etc.
$44.s5
•
• A ready to go system, no installation
required • Fully automatic operation , very
user friendly • Large coverage area •
Portable or wall mounted • Long life 9V
battery operation (battery not included) •
Battery low warning • Lightweight,
compact and attractive.
_$,P8'.
__.o_o._T_h_is_M_o_nt_h_$_4_9_ ._oo_
.....
s _53_0_5
Super Heavy Duty
Tripod
$129
A tlt1C,n1,
r~
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174 Roe St. Perth W.A. 6000 Phone (09) 328 1599
PHONE TOLL FREE 008 999 007
MAIL ORDERS C/- P.O. Box 8350 Stirling Street PERTH W.A. 6849
STANDARD DELIVERY & PACKING CHARGE $5.50 to 1Kg, $8 1Kg-5Kg AUSTRALIA
WIDE - We process your order the day received and despatch via. Australia Post. Allow
approx 9 days from day you post order to when you receive goods.
OVERNIGHT JETSERVICE Up to 3Kg is $10.00, 3Kg to 5Kg is $23.00 - We process your
order the day received and despatch via. Overnight Jetaervfce Courier for delivery next day
Country areas please allow additional 24-48 hours.
~
_,,,=;_
'D' Series Connectors
Wai
: ~g~ 069 Male solder connector
DB9 Female solder connector
P3020 069 Male 90' PCB connector
.,_c_o_3_15_ _ _._95_ _ _ _ _ _ _ _ _ _ _ _-t :
069 Female 90' PCB connector
DB9 Male straight PCB connector
p 3050 069 Female straight PCB connector
P 3090 069 Backshell Cover
sAVE ovER
p 3100 0B15 Male solder connector
COMPETITORS
P 3110 DB15 Female solder connector
0615 Male 90° PCB connector
PRICES!
DB15 Female 90' PCB connector
This great new model holds an amazing
p 3140 0615 Male straight PCB connector
range of equipment. With rubber feet for
p 3150 0615 Female straight PCB connector
sure and stable grip. Anti-sway bars on
p 3190 DB 15 Backs hell Cover
legs prevents wobbling. Adjustable
p 3200 DB25 Male solder connector
height from approx 1 to 2 metres.
p 3210 0825 Female solder connector
Lightweight aluminium construction and
p 3220 DB25 Male 90' PCB connector
collapsable for easy transportation.
p 3230 DB25 Female 90' PCB connector
Removeable mounting plate makes this
p 3240 0B25 Male straight PCB connector
tri-pod ideal for amplifiers, speakers,
p 3250 0625 Female straight PCB connector
lighting etc.
p 3290 DB25 Backshell Cover
P3310 Spacer Screws pk 1O
C 0520
.95
P 3312 Spacer Screw pk 100
$79
(il
~g:g
:mg
.. ..
10 Up
$1.35
$1.35
$2.00
$2.00
$1.75
$1.75
$1.75
$1.55
$1.55
$2.25
$2.25
$1.90
$1.90
$2.00
$1.75
$1.75
$2.85
$2.85
$2.25
$2.25
$2.25
$4.45
$35.95
$1.20
$1.20
$1.80
$1.80
$1.60
$1.80
$1.80
$1.40
$1.40
$2.00
$2.00
$1 .70
$1 .70
$1.80
$1.80
$1.60
$2.40
$2.40
$2.00
$2.00
$2.00
HEAVY HEAVY SERVICE - All orders of 10Kgs or more must travel Express Road - Please
allow 7 days for delivery. $12.00 to 10Kgs. $15.00 over 10Kgs.
INSURANCE - As with virtually every other Australian supplier, we send goods at
consignees risk. Should you require comprehensive insurance cover against loss or
damage please add $1 .00 per $100 of order value (minimum charge $1 ). When phone
ordering please request " Insurance".
TOLL FREE PHONE ORDER - Bankcard , Visa, Mastercard Holders can phone order toll
free up to 6pm Eastern Standard Time. Remember with our Overnight Jetaervfce we deliver
next day.
AL TRON ICS RESELLERS Chances are there is an Altronic Reseller right near
you - check this list or phone us tor details of the nearest dealer.
Blue Ribbon Dealers are highliQhted with a ■ These dealers generally carry a
comprehensive range of Altron,c products and kits or will order any required item tor
you.
WA. COUNTRY ALBANY BP Electronics ■ (098) 412681 Micro Electronics (098) 412077 BUN■URY Micro Electron let (097) 216222 UPIRANCE Eeperance Communlcatlona (090)
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iO,.<ONGONG ••~• '"''""'~ • ,,.,, """'· ,O~om ,,.mrn,;o, (00) ,,.,oo.
INFRARED REMOTE
CONTROL FOR MODEL
RAILROADS, PT.2
In this second article on our new remote control
for model railroads, we present the circuitry for
the remote control receiver. This mates up to the
pulse power board described last month. It also
providesJatched and momentary outputs which
can be used to control signalling, points and
lighting on a model railway layout.
The receiver circuit comprises eight
ICs plus quite a few transistors and
diodes, as shown in Fig.7. IC5 and
IC6 are . the infrared remote control
devices, while IC7, IC8, IC9, IC10a
and ICl la provide the control signals
for the pulse power circuit. Finally,
IC10b, ICllb and IC12 are used for
the various latched outputs.
IC5 , a Plessey SL486 infrared preamplifier IC, is specifically designed
for processing infrared control signals. This device features a differential photodiode input to reduce noise
pickup and an automatic gain control
circuit for improved operation in noisy
By LEO SIMPSON & JOHN CLARKE"
76
SILICON CHIP
·'
environments. It also incorporates two
gyrator circuits and these allow the
device to receive signals in high ambient lighting conditions, such as from
incandescent lamps.
The incoming IR signals from the
remote control transmitter are picked
up by photodiode IRDl which is connected across the differential inputs
of IC5. The received pulses are then
amplified and filtered before they appear at pin 9. Capacitors connected to
pins 2, 3, 5, 6 and 15 ofICl roll off the
frequency response of the gyrator and
gain stages below about 2kHz. This
effectively filters out any 100Hz signals produced by mains-powered
lamps.
Automatic gain control is provided
by an internal peak detector which
measures the output signal appearing
at pin 9. A O. lµF capacitor at pin 8
filters the output of the peak detector
and the resulting signal is used to
control the gain of the first three amplifier stages.
Signal decoding
The signal from pin 9 of IC5 is
directly connected to pin 1 of IC6, the
decoder IC. This provides five BCD
(A, B, C, D & E) outputs which can be
either momentary or latched, depending on whether pin 5 is high or low.
We have selected momentary operation by tying pin 5 high.
In addition to the five BCD outputs,
IC6 provides a Data-bar signal which
goes low whenever a valid code is
present on the A, B, C, D & E outputs.
This signal is used to drive the
ACKnowledge LED (LED 6) via a 3300
resistor. This LED therefore indicates
whenever the remote control circuitry
is receiving a valid signal from the
transmitter.
Pins 3 and 4 are the A and B rate
inputs and must be connected to
match the transmitter rate input connections. When the links to these inputs are left open, internal resistors
tie them high (ie, to +12V).
Three of the BCD outputs from IC6
are connected to IC7, a 4051 3-8 decoder (also known as an analog multi-
plexer). Depending on the BCD code
presented to its inputs, IC7 pulls one
of its eight outputs (pins 1, 2, 4, 5, 12,
13, 14 & 15) high. Actually, what really happens is that one of the eight
pins is connected to the common pin
(3) which is tied to +12V via a 2.ZkQ
resistor.
The A, B and C inputs of IC7 are
only decoded when the INHibit input
(pin 6) is low. This input is connected
to the Data-bar output of IC5 via a
lOkQ resistor so that decoding is done
only when valid data (low output) is
present on the A, B and C inputs.
Note that pin 6 of IC7 is also controlled by the D and E outputs of ICZ
via diodes D15 and D16. Thus, when
either the D or E output goes high, it
inhibits IC7 and prevents any of its
outputs from going high.
Logic level conversion
IC5 and IC6 operate between the
+12V and +7V supply rails, while IC7
operates from +12V, +7V and 0V. The
reason for this messy arrangement is
because IC6 requires a 5V supply
while the rest of the circuit needs to
be compatible with the pulse power
PC board which operates at 12V.
Thus, IC7 not only decodes the signals from IC6 but also provides logic
level conversion so that its output
signals swing between 0V and +12V.
The +12V supply for the circuit is ·
obtained from the +12V regulator on
the pulse power PC board, while the
+7V supply is derived from a separate
-5V 7905 2-terminal regulator. This
may seem a little unusual but the
7905 effectively operates as a current
sink and subtracts its 5V from the 12V
rail to give the +7V rail.
Auxiliary outputs
The five auxiliary control outputs
are derived from the "5", "6" and "7"
outputs of IC7 and the D and E outputs of IC6. The "5", "6" and "7"
outputs of IC7 connect to the clock
inputs of D-flipflops IC12a, ICl0b &
ICl lb respectively. These are each
Shown below is the completed pulse
pow.er board, together with the handheld controller that's used to test it.
These two items are identical to the
Railpower project published in the
April 1988 issue of SILICON CHIP,
which means that you can easily
convert the original project to remote
control.
MAY1992
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Fig. 7 (left): the receiver board decodes
the signals from the infrared
transmitter. IC5 (preamplifier) & IC6
(decoder) are the infrared remote
control devices; while IC7, IC8, IC9,
IC10a & IClla provide the control
signals for the pulse power circuit.
IC10b, ICllb & IC12 are used to
provide latched outputs for signalling,
points switching & lighting.
OV
+12V
BUZZER
+
connected with the D input tied to the
Q-bar output so that each time their
clock input goes high, the Q output
changes state, from a low to a high or
from a high to a low.
This provides the latched output
facility so that the first press of a
button on the transmitter latches the
relevant output on and the next press
latches it off.
The Reset inputs of these flipflops
are all tied to an RC netw ork consisting of a O. lµF capacitor and lOOkQ
resistor. This provides a power-on reset facility. At power-on, the O. lµF
capacitor is discharged and so the
reset line is momentarily held high
until the voltage drops to OV via the
lOOkQ resistor. This resets each flipflop so that its Q output is low.
The Q outputs of IC12a, IClOb and
ICl 1b are connected to transistors
Q13, Q12 and Q11 to provide the
latched outputs. Alternatively, the
flipflops can be bypassed, via a link
option, for momentary operation.
Each of the three transistors can
drive a 12V relay, connected between
the collector output and the+ 12V supply. Each transistor has an associated
diode to provide protection against
any spike voltages that may be generated when a relay is switched off.
Also associated with each transistor
is a LED (LEDs 5, 6 & 7) which is lit
when the output is on.
The D and E outputs of IC6 drive
transistors QlO and Q9, each via a
6.8V zener diode (ZD5 and ZD4) and
a 2.ZkQ resistor. These provide momentary outputs only and, as with the
other three outputs, have LEDs (LED4
and LED3) to indicate when they are
on.
The 6.8V zener diodes are used because the D and E outputs ofIC6 are at
+7V when off (low) or +12V when on
(high). When the outputs are at +7V,
the zener diodes prevent the transistors from turning on. Note that Q9
and QlO are high gain Darlington tran-
LE02
vdf I
Fig.8: this is the parts placement diagram for the pulse power PC board.
Note that IC2 is oriented differently to the other !Cs & take care to ensure
th~t the two heatsinks used for transistors Q1-Q4 do not touch each other.
Tnmpots VRl & VR2 set the maximum and minimum track voltages & must
be adjusted as described in the text.
sistors which are needed due to the
limited base drive available from the
D and E outputs of IC6.
Train control
The remaining circuitry on the receiver board is used to provide the
various throttle functions via the pulse
power board. You will need to refer to
the circuit diagram of the pulse power
board published last month to be able
to fully understand the circuit description to follow.
There are six connections from the
receiver board to the pulse power
board. Terminals 1 and 2 provide connections for the minimum and maximum speed setting voltages (from
VRl, VRZ , ICla & IClb on the pulse
power board). Terminal 3 is the speed
control voltage (fed to pin 3, IClc on
the pulse power board), while terminals 4, 5 and 6 provide the OV connection and the forward/reverse control.
Each of the terminal 1, 2 and 3
points on the receiver board feature
input protection for the CMOS circuitry. This takes the form of a 12n
series resistor and 12V zener diode to
ground (OV).
The "O" and "1" outputs of IC7
(pins 13 & 14) correspond to the
"faster" and "slower" buttons on the
remote control transmitter. They con-
nect to the control inputs of CMOS
analog switches IC8a and IC8b.
When pin 13 ofIC7 goes high (corresponding to the "faster" button being pressed), switch IC8a closes and
the 2.ZµF capacitor at pin 3 of IC9a is
charged via a 1OMQ resistor connected
to the +12V rail. When pin 14 of IC7
goes high (when the "slower" button
is pressed), switch IC8b closes and
discharges the 2.ZµF capacitor via the
lOMQ resistor connected to OV.
The 2.ZµF capacitor can charge no
higher than the voltage at Terminal 2
and can discharge no lower than Terminal 1. This is achieved by clamping
diodes DlO and Dll and the associated resistive voltage divider between
Terminals 1 and 2.
The reason for using this fairly complicated capacitor charging, discharging and clamping arrangement is to
give more linear charging and discharging and thus a better throttle
response from the transmitter buttons.
Sample and hold
The voltage across the 2.ZµF capacitor is buffered by FET-input op
amp IC9a which acts as a sample and
hold circuit. This is desirable because
the capacitor voltage is the throttle
setting; you don't want it changing
after it has been set. Since the op amp
MAY 1992
79
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VR5
000
following 4 7µF capacitor on the pulse
power board will take several minutes to charge to the throttle setting,
thus simulating the inertia of a real
train. Conversely, if VR4 is set for
minimum resistance, there will no
inertia, which might be desired for
shunting manoeuvres.
Braking
Fig.9: this is the wiring diagram for the
temporary handheld controller. The
numbers on the leads correspond to the
numbers on the terminal block at the top
of Fig.8. VR4 and VR5 set the running &
braking inertia.
FROM MAIN
BOARD
IC10a, IC8d and VR5 control the
braking. IC10a is a D-flipflop which is
normally set with its Q output (pin 1)
low and its Q-bar output (pin 2) high.
The high on pin 2 closes switch IC8c
for the normal run mode (ie, normal
running, brake not applied).
When the stop output (pin 15) of
IC7 goes high, flipflop IC10a changes
state. Thus, pin 2 of IC10a goes low,
causing analog switch IC8d to open. ,
At the same time, pin 1 of IC10a goes
high and closes analog switch IC8d to
discharge the 47µF capacitor connected to Terminal 3 of the pulse
power board via trimpot VR5. This is
the braking mode. The degree of braking is set by adjusting VR5.
Hence, pushing the Stop button on
the transmitter will cause the braking
circuit to activate and it then stays
that way until the Faster button is
depressed (a momentary press is all
that is required). When this happens,
the "Faster" output of IC7, pin 13,
goes high and pulls reset pin 4 of
IC10a high via diode Dl4. This resets
IC10a's Q output to low and the Q-bar
output high. Switch IC8d now opens
and switch IC8c closes to revert to
normal running.
Forward/Reverse
This view shows how everything fits together inside the hand-held control unit
that's used to test the pulse power board. A 6-way telephone cable makes a
handy connecting lead.
dr'aws an extremely low current (typically 50 picoamps), the rate at which
the capacitor discharges will be almost solely due to its own leakage
current.
In practice, a typical 2.2µF tantalum capacitor should hold a voltage
across it for five minutes or more before any noticeable reduction occurs.
The output of op amp IC9a is at the
80
SILICON CHIP
same voltage as the capacitor and is
used to drive the speed setting meter
via trimpot VR6. IC9a also drives inertia pot VR4. Normally, the following analog switch, IC8c, is closed and
the run inertia pot connects to Terminal 3 of the pulse power board. This
input has a 47µF capacitor which is
charged via VR4 to set the train speed.
If VR4 is set for high resistance, the
Forward/reverse control is provided
with flipflop ICl la. This is initially
set at power-on with its Q output (pin
1) high and th~ Q-bar output (pin 2)
low. These outputs are connected to
Terminals 5 and 6 and thence to the
pulse power board. Thus, when power
is first applied, the circuit is set in the
forward mode.
When the Reverse output - pin 1 of
IC7 - goes high, it pulls pin 4 of ICl la
high to reset it. This causes the Q
output to go low and the Q-bar output
to go high. This is the reverse mode.
Forward/reverse lockout
However, there is more to the forward/reverse control than this. IC9b
is an op amp connected as a comparator. It compares the voltage at Termi-
nal 3 with the voltage set by VR3.
In practice, VR3 is adjusted so that
the output ofIC9b goes low only when
the voltage at Terminal 3 is so low
that the train is either running very
slowly or has completely stopped. If
the voltage at Terminal 3 is higher
than the setting ofVR3, IC9b's output
will be high; this is the normal condition while the train is running.
The high output from IC9b turns on
transistor Q14 and thereby pulls both
the set and reset of IC11a low via
diodes D12 and D13. This prevents
ICl la from changing state and so prevents a change in direction; ie, gives
forward/reverse lockout unless the
loco speed is zero or very low. This
condition causes the For/Rev Off indicator, LED 9, to light.
If the For/Rev Off indicator is alight,
you cannot change the direction of
the loco.
Construction
We now come to the construction
procedure for the pulse power controller. It is housed in a standard plastic instrument case and has two PC
boards, as already mentioned. The
power transformer and the receiver
board are mounted on the base of the
case, while the pulse power board is
mounted on the lid.
We will first describe the assembly
of the pulse power board and show
you how to get it going as a selfcontained train controller. After that,
we will tackle the construction of the
transmitter and receiver and marry
them to the pulse power board.
Fig.8 shows how the parts are
mounted on the pulse power board.
The 6-way connector is for the connections to the receiver board (Terminals 1-6), while the 16-way connector
(actually two 8-way units) is for the
rest of the connections.
Assembly of the board can start with
the wire links, small diodes and the
resistors. When these have been installed, you can concentrate on mounting the four output transistors, the 3terminal regulator and their associated h eatsinks.
Three heatsinks are required. Ql
and Q3 are mounted on one heatsink
while Q2 and Q4 are mounted on
another. We made ours from 0.8mm
aluminium (equivalent to 22 gauge),
although the thickness is not important.
For each two-transistor heatsink, we
RESISTOR COLOUR CODES
Value
4-Band Code (1%)
5-Band Code (1%)
10MQ
brown black blue brown
green blue yellow brown
red red yellow brown
brown red yellow brown
brown black black green brown
green blue black orange brown
red red black orange brown
560kn
220kQ
120kQ
100kQ
47kQ
27kQ
22kn
15kQ
10kQ
8.2kQ
5.6kQ
4.7kQ
2.2kQ
1kO
8200
3300
1000
47Q
brown black yellow brown
yellow violet orange brown
brown red black orange brown
brown black black orange brown
yellow violet black red brown
red violet orange brown
red red orange brown
brown green orange brown
brown black orange brown
grey red red brown
red violet black red brown
red red black red brown
brown green black red brown
brown black black red gold
grey red black brown brown
green blue red brown
yellow violet red brown
red red red brown
brown black red brown
grey red brown brown
orange orange brown brown
green blue black brown brown
yellow violet black brown brown
brown black brown brown
yellow violet black brown
120
2.20
brown red black brown
red red gold brown
used a piece of aluminium 30mm wide
and 55mm long, with a rightangle
bend 9mm from one end, which becomes the foot. Four 3mm holes need
to be drilled in each heatsink, to take
the two mounting screws for the foot
and the mounting screw for each transistor.
For the 3-terminal regulator heatsink, we used a piece of aluminium
CAPACITOR CODES
Value
IEC Code
EIA Code
0.1µF
100n
104
0.022µF
0.015µF
0.01µF
0.0047µF
22n
15n
10n
223
153
103
4n7
n10
472
101
100pF
TRIMPOT CODES
Value
220kO
100kQ
10kO
2.2kQ
EIACode
224 .
104
103
222
red red black brown brown
brown black black brown brown
grey red black black brown
orange orange black black brown
brown black black black brown
yellow violet black gol~ brown
brown red black gold brown
red red black silver brown
20mm wide by 45mm long, with a
rightangle bend 9mm from one end.
Three 3mm holes need to be drilled in
it, two for mounting screws and one
to secure the regulator.
The three heatsinks should be secured to the PC board before the transistors and regulators are soldered into
place. Note that the two transistor
heatsinks must not touch each other
otherwise they will short out the DC
supply. Attach the regulator and the
power transistors to their respective
h eatsinks and then you can solder
their leads to the board.
Note that mica washers are not necessary for the transistors or for the
regulator.
Once the transistors and regulator
are in place, the rest of the components can be mounted on the PC board.
We suggesrthat you solder in the small
transistors first , then the two trimpots, the 5W wirewound resistor, the
four ICs, the four rectifier diodes and
the capacitors. Leave the connector
strips till last, otherwise they tend to
get in the way when you are soldering
other components.
Note that ICl and ICZ, the two
LM324 op amps, are oriented differMAY 1992
81
PARTS LIST FOR IR MODEL TRAIN CONTROLLER
Case & hardware
1 plastic instrument case, 260 x
190 X 80
1 aluminium front panel
1 Dynamark front panel label,
250 x 75mm
1 M2165 60VA transformer
1 piece of 1.5mm gauge
aluminium, 120 x 165mm
1 piece of 0.6mm gauge
aluminium, 80 x 60mm
1 MU45 1mA meter
1 meter scale, 51 x 41 mm
9 5mm LED bezels
1 16mm nylon bushing
1 1MQ linear pot (VR4)
1 15mm diameter knob
1 9.5mm nylon cable clamp
1 3-way mains terminal block
1 cordgrip grommet for mains
cord
1 panel mount 3AG fuse holder
1 1A 3AG fuse
2 solder lugs
2 panel mount banana sockets
1 12V buzzer
6 4BA 9mm Nylon screws plus
nuts
4 6mm standoffs
Wire & cable
1 mains cord with moulded 3-pin
plug
1m 5-way rainbow cable
400mm 4-way rainbow cable
400mm brown medium duty
hookup wire
400mm blue medium duty
hookup wire
150mm blue mains rated wire
400mm brown mains rated wire
200mm green/yellow mains
(earth) wire
200mm red light duty hookup
wire
200mm black light duty hookup
wire
200mm green light duty hookup
wire
200mm red medium duty
hookup wire
200mm yellow medium duty
hookup wire
200mm blue medium duty
hookup wire
Miscellaneous
Tinned copper wire , solder,
82
SILICON CHIP
screws, nuts, self tapping
screws, heatshrink insulating
tubing, etc.
Pulse power board
1 PC board, code SC91488, 117
x 125mm
2 8-way PC board mount screw
connectors
1 6-way PC board mount screw
connector
2 100kQ miniature vertical trim
pots (VR1, VR2)
Semiconductors
2 LM324 quad op amps (IC1,
IC2)
1 4093 quad Schmitt NAND gate
(IC3)
1 4049 hex inverter buffer (IC4)
2 BD650 PNP Darlington
transistors (01 , 02)
2 BD649 NPN Darlington
transistors (03, 04)
3 BC547 NPN transistors (05,
06, 08)
1 BC558 PNP transistors (07)
1 7812 12V 3-terminal regulator
5 1N914, 1N4148 signal diodes
(D1-D5)
4 1N5404 3A diodes (D6-D9)
1 5mm bicolour LED (LED1)
1 5mm red LED (LED2)
Capacitors
2 2200µF 25VW PC electrolytic
1 47µF 16VW PC electrolytic
1 10µF 16VW PC electrolytic
1 4.7µF 16VW PC electrolytic
1 2.2µF 25VW PC electrolytic
1 2.2µF 16VW PC electrolytic
2 0.1 µF MKT polyester or
greencap
1 0.01 µF MKT polyester or
greencap
Resistors
(0.25W or 0.5W,
1 560kQ
1 220kQ
2 120kQ
5 100kQ
1 27kQ6
1 22kQ1
2 15kQ1
1%, 7mm body)
5 10kQ
1 8.2kQ
2 5.6kQ
6 2.2kQ
1kQ
100Q
0.1Q 5W
Transmitter board
1 plastic case, 68 x 130 x 43mm
1 PC board, code SC15204922,
88 X 57
1 front panel label, 63 x 125mm
4 black PC board mount
momentary switches
4 white PC board mount
momentary switches
1 grey PC board mount
momentary switch
1 red PC board mount
momentary switch
1 216 9V battery
1 216 9V battery clip
4 6mm standoffs
4 2mm x 20mm countersunk
screws
12 2mm nuts
4 2mm washers
1 160mm-length 0.8mm tinned
copper wire
1 CSB615A 615kHz Murata
ceramic resonator (X1)
Semiconductors
1 MV500 Plessey remote control
transmitter (IC1)
1 BC338 NPN transistor (01)
1 B0140 PNP transistor (Q2)
2 COY89A, LD271 infrared
LEDs (LED1, LED2)
Capacitors
1 220µF 16VW PC electrolyfic
2 100pF ceramic
Resistors
(0.25W or 0.5W, 1%, 7mm body)
1 10kQ
1 100Q
1 1kQ
1 2.2Q
1 820Q
lnfrared receiver board
1 PC board, code SC15204921,
140x98mm
1 CSB615A 615kHz Murata
ceramic resonator
1 220kQ miniature horizontal
trimpot (VR5)
1 10kQ miniature horizontal
trimpot (VR3)
1 2.2kQ miniature horizontal
trimpot (VR6)
Semiconductors
1 SL486 Plessey infrared
receiver amplifier (IC5)
1 MV601 Plessey remote control
receiver (IC6)
1 4051 8-channel analog
mutiplexer (IC?)
1 4066 quad analog switch
(IC8)
1 LF351, TL072 dual FET input
op amp (IC9)
3 4013 dual D flipflops
(IC10,IC11,IC12)
2 BO681 NPN Darlington
transistors (09, 010)
4 BC338 NPN transistors (011014)
1 BP104, BPW50 infrared
detector diode (IRD1)
7 1N4148, 1N914 signal diodes
(D1 0-D17)
5 1 N4002 1A rectifier diodes
(D18-D22)
3 12V 400mW zener diodes
(ZD1-ZD3)
2 6.8V 400mW zener diodes
(ZD4-ZD5)
1 7905 5V negative regulator
7 5mm red LEDs (LED3-LED9)
00
00
"f
,...
I
en
Capacitors
1 68µF 16VW PC electrolytic
1 22µF 16VW PC electrolytic
3 10µF 16VW PC electrolytic
1 6.8µF 16VW PC electrolytic
1 2.2µF tantalum electrolytic
6 0.1 µF MKT po lyester
1 .022µF MKT polyester
1 .015µF MKT polyester
1 .0047µF MKT polyester
2 100pF ceramic
Resistors
(0.25W or 0.5W,
2 10Mn 5%
11 100kQ
1 47kQ
410kn
1 8.2kQ
1 4.7kn
1%, 7mm body)
3 2.2kQ
10 1kQ
1 3300
1 47Q
3 12Q
Parts for hand controller
(for testing pulse power
board)
1 plastic case, 83 x 54 x 28mm
1 1 0kQ linear pot. (VR3)
1 1 MQ trimpot (VR4)
1 220kQ trimpot (VR5)
2 SPOT togg le switches (S1 ,S2)
1 piece of Veroboard (50 x
20mm)
1 6-way cable (to connect to
pulse power board)
u
en
~
Fig.10: compare your etched PC board against this full-size artwork & correct
any defects before mounting any of the parts.
ently on the board (ie, they point in
different directions).
Testing
Instead of now proceeding to assemble the infrared transmitter and
receiver, we suggest that the pulse
power board be assembled into the
case, along with the power transformer, some of the LEDs and so on.
We will assume that you have purchased the full kit so there will be no
need to do any metalwork, although
you may have to drill holes in the
plastic instrument case - see Fig.11.
In effect, you will initially be wiring up the complete project minus the
receiver board. We will then show
you how to wire up a simple hand
control (the same as published in our
April 1988 issue) so that you can put
the pulse power board through its
paces.
The 60VA transformer is mounted
on a metal plate in the lefthand side
of the case. The metal plate (we used
20-gauge aluminium sheet) is then
secured to the case using four of the
integral plastic pillars in the base. A
3-way insulated terminal block is required to terminate the mains wiring
to the power switch and transformer.
The mains Earth (green/yellow) wire
is terminated to a solder lug which is
attached to the transformer mounting
plate.
The mains wires to the power
switch and fuseholder should be fitted with heatshrink sleeving to prevent any accidental contact. When
fitting the mains cord, make sure it is
anchored to the rear panel of the case
using a cordgrip grommet.
Mount the pulse power board on
the lid of the case with four screws
and nuts. We used nylon screws for
this job since they are safer and the
screw heads are less noticeable on the
lid. Lay the lid, with the pulse power
board fitted to it, to the right of the
base and run the necessary wiring.
The two transformer secondary windMAY 1992
83
Fig.11: this diagram is provided
to enable you to initially install
the pulse power board, power
transformer & mains wiring. The
pulse power board can then be
tested with a hand-held throttle
(see Fig.9). The installation of the
receiver PC board & the rest of
the wiring will be described next
month.
PULSE POWER PCB
ON l:ASE LIO
11
ALUMIN IUM FRONT PA~NEL
LED7 A
-
PLASTIC REAR PANEL
6
5
-
)A
5
pf-A
TRACK
OUiPUT
TERMINALS
INFRAREO RECEIVER PCB
p=ol
LEDB
A
I
LED9
~
K
L~ f~
4-~A
1~1/1
K
2
LED1 K
I
OUTPUTS
TO RELAYS
ALUMINIUM BASE PANEL
F1
84
SILICON CHIP
LEO4
. .
LE~)
-e ~
1.,,.,..
A. ~
~~ A
GROMMETG
e
3
~===================~s1
1
6
,
r~ .
The run & stop inertia adjustment pots (VR4 & VR5) in the hand-held controller
are mounted on a small piece of Veroboard. Note: these pots are optional for
testing purposes & could be replaced by wire links.
ings are connected in parallel (0V to
0V and 12V to 12V) before being connected to the relevant points on the
connector strip.
You can also wire in the overload
buzzer and the output (track) leads
which connect to binding post terminals on the rear panel. The LEDs can
be connected directly to the connector strip at this stage, leaving the permanent wiring till later.
Handheld control
To test the pulse power board, you
will need a handheld control and we
have shown one wired up on Veroboard in Fig.9. It is wired up to Terminals 1-6 on the pulse power board.
Switch Sl functions as a Run/Stop
switch while switch S2 provides forward and reverse. VR3 becomes the
main speed control, VR4 the inertia
control, and VR5 the braking control.
However, don't wire in the control
until you have made the following
voltage checks.
Powering up
Having completed the wiring, check
your work carefully and then apply
power. A number of voltage checks
should now be made. To make these
easier, orient the pulse power board
in the same direction as the diagram
of Fig.8 and have last month 's issue
open at the circuit diagram on page
70. That way, it will be easier to find
your way around the board.
Switch your multimeter to the 20V
DC range and check that + 17V is
present at the IN terminal of the 3terminal regulator (you can pick it up
at the end of the adjacent 2.2kQ resistor) and at the emitters of Ql and Q2.
Depending on the incoming mains
voltage, this measurement is likely to
be anywhere between+ 17V and +21 V,
or even a little more.
TABLE 1
IC
Pins
Voltage
IC1
1, 2, 3
+1.2V
IC1
5,6, 7
+4.8V (triang le
waveform at pin 9,
square wave at pin 7
IC1
8, 9, 10
Same as wiper of
VR1
IC1
12, 13,
12
Same as wiper of
VR2
IC2
1
+11V
IC2
2
ov
IC2
3
+0.6V
IC2
5
10.1V
IC2
6
+9.8V
IC2
7
+12V
IC2
8,9, 10
Close to 0V
IC2
12
+1 .8V
IC2
13
Same as pin 6, IC1
IC2
14
ov
Now check for +12V at the output
of the 3-terminal regulator and on each
of the supply pins of the ICs: pin 4 of
ICl and IC2, pin 1 ofIC4, and pin 14
of IC3. Again, the actual voltage will
vary between +ll.4V and +12.6V, depending on the actual 7 812 (or
LM340T-12) used.
The voltages around !Cl and IC2,
as shown in Table 1, should now be
checked with the handheld throttle
disconnected. These voltages are
"ballpark" figures only but should be
a good guide to see that things are
working.
Now you can wire in the handheld
control and check that the voltages at
pins 3 and 4 swap from high to low or
vice versa when the forward/reverse
switch is operated. Check that the
voltages at pins 6, 7, 9, 10, 11, 12, 14 &
15 also change state when the forward/reverse switch is operated.
Now connect your multimeter
across the output terminals of the controller and wind the throttle control
up to maximum. Adjust VRl on the
pulse power board so that the voltage
is 12V (or whatever is the maximum
recommended operating voltage for
your locos). Now rotate the throttle to
the minimum and adjust VR2 for an
output of 1.5V (you will want to "fine
tune" this minimum setting once you
start operating trains).
Now note that the polarity of the
output voltage changes when you operate the forward/reverse switch and
that the colour of the track LED
changes (from red to orange or vice
versa).
Now wind the throttle to about the
half-way mark and briefly short the
output terminals. The overload LED
should light and the buzzer should
sound.
You can also listen to the operation
of the controller by connecting a loudspeaker to the output terminals via a
l00Q resistor. (Don't connect it directly otherwise you'll probably blow
the loudspeaker). At low throttle settings, the loudspeaker will have a thin,
reedy sound. At higher settings, the
sound will be louder but more mellow.
With all those checks made, you
can now run trains if you like. After
all, you probably want a break from
soldering at this stage. Next month,
we shall complete the project by presenting the assembly details of the
infrared transmitter and receiver. SC
MAY 1992
85
AMATEUR RADIO
BY GARRY CRATT, VK2YBX
Receiving weather satellite signals; Pt.2
Last month, we looked at the polar orbiting
weather satellites and discussed the equipment
necessary to receive and decode images
transmitted by them. This month, we look at the
SHF transmissions which originate from the
Japanese GMS-4 satellite.
The Japanese GMS-4 satellite is located in geostationary orbit at 140°
east. This satellite transmits enhanced
images on a frequency of 1691MHz,
requiring the use of microwave techniques for good quality reception.
When one considers the minute signal levels reaching the Earth's surface
(typically .05µV), it becomes apparent that considerable care must be
taken to receive and display weather
images from this satellite. The GMS
satellite uses a deviation of ±126kHz
and so the receiver must have a minimum IF bandwidth of 260kHz. This
increased bandwidth means that the
received noise is about 10 times larger
in amplitude than from a VHF polar
orbiting satellite having a deviation
of ±18kHz.
In order to recover useable signals ,
the antenna must be capable of pro-
This image from the Japanese GMS-4 satellite clearly shows the cyclone that
eventually crossed the Queensland coast during March 1992.
86
SILICON CI-IIP
viding sufficient gain between the incoming signal level of -134dBm and
the typical receiver sensitivity of
-1 lOdBm. This equates to a gain of
26dB, requiring a dish having a diameter of at least 1. 5 metres. Such dishes
are often available from satellite TV
dealers, who often have damaged units
of no use at 12GHz but still quite
useable at the frequency of the GMS
satellite. Fig. l shows the gain that can
be expected from dishes of various
_diameters.
The path loss between spacecraft
and Earth at 1691MHz is approximately 188dB and as the output signal from the satellite is 5W (+37dBm),
and the gain of the spacecraft antenna
is around 17dBi, the calculated signal
at the ground is -134dBm.
Receiver requirements
To obtain a good signal, the receiver
should also have a noise figure of
around 1.5-ZdB. A popular configuration is to use a microwave mixer and
local oscillator chain feeding a VHF
receiver. Particular care must be taken
to ensure that the local oscillator is
kept as stable as possible: it will be
oscillating at about 1500MHz, to produce an IF of 137MHz (for example),
and any drift in the oscillator will be
multiplied by 15 or so (assuming the
oscillator runs a 20MHz crystal). Thus,
a frequency offset of lkHz will become a shift of 75kHz at 1500MHz.
The most important parameter of
the GMS receiving system is the IF
bandwidth of the receiver. Some
weather satellite enthusiasts have attempted to use scanning receivers for
the purpose, as they cover the SHF
frequency range. However, these receivers have a wideband FM bandwidth of 150-lB0kHz, causing poor
signal-to-noise ratio and severe limiting of greyscale resolution. A correctly
ing this distance for maximum signal.
Fortunately, for those without the
resources or time to construct a GMS
system, specially designed and prebuilt components .are available. PH
Communications - phone (07) 264
1575 - produces a built up GMS receiver, downconverter and dipole feed
system. They also produce a suitable
1.7GHz LNA (low noise amplifier) for
those who think they need it. S.CISAT
Products are finalising a complete
GMS receiver/downconverter. QUORUM Communications (address details in last month's issue) produce a
suitable downconverter, model SDC16918.
Polar orbiters
Taken from one of the NOAA polar orbiting satellites, this infrared image of the
United Kingdom shows quite a lot of detail, including many small towns.
designed receiver must have an IF
bandwidth of 260-280kHz.
Unfortunately, most receiver designs featured in overseas magazines
are suitable only for METEORSAT or
GOES satellites, which have an IF
bandwidth of 40kHz. With this kind
of signal improvement over GMS
transmissions (+8.25dB), signals can
be heard on four phased Yagi antennas. While GMS transmissions can be
heard using such equipment, pictures
cannot be produced, due to the reduced signal levels.
As 1691MHz is a frequency used
exclusively for weather satellite transmissions, commercial feedhorns for
this frequency are not readily available. Because the efficiency of the
dish is related to the type of feedhorn
arrangement used, the design of this
component is also very important. The
first step towards constructing a suitable feedhorn is to determine the focal point of the dish, so that the
feedhorn can be correctly positioned.
This can be calculated using the formula F = D2 /2c, where F is the focal
point, D is the diameter and c is the
depth of the dish.
Designs for "coffee can" feedhorns
can be found in the ARRL Antenna
Book, and Jessop's VHF UHF Manual.
A table in the latter book shows both
the 3dB and lOdB beam width required
for various values of F/D. This table
enables constructors to select a suitable feedhorn design, once the F/D of
the dish is known, ensuring that the
dish is fully illuminated and operating at peak efficiency.
As an example, a feedhorn suitable
for a dish having an F/D ratio of 0.56
can be constructed using a 12cm long,
18cm wide can, containing a quarter
wavelength monopole (3cm), mounted
3cm from the rear of the tube. The
focal point is measured from the inside centre of the dish to the inside
edge of the feedhorn.
As is the case with all microwave
receiving systems, the feed must be
rotated to the correct satellite polarity, corresponding to maximum signal level, and the focal point should
also be fine tuned by carefully adjust-
Fig.1: Dish Diameter vs. Gain
Diameter
Gain (dBi)
0.6
18
1.2
24
1.5
26
1.8
27.5
2.0
29
2.4
30
3.0
32
There is yet another mode of transmission used by the polar orbiting
weather satellites described in our first
article. These polar orbiters produce
extremely high resolution pictures and
the data is transmitted on frequencies
similar to GMS.
In the case of NOAA 9 & 11, this
frequency is 1707MHz. For NOAA 10
it is 1698MHz. Data is collected from
spacecraft instruments such as the
Advanced Very High Resolution Radiometer (AVHRR), the Operation Vertical Sounder (TVOS), the Space Environment Monitor (SEM), the Data
Collection System (DCS) and the
spacecraft telemetry system.
The subject of HRPT signal reception is quite complex and extremely
interesting. Dedicated newsletters for
enthusiasts are available, such as the
Journal of the Environmental Satellite Amateur Users Group. This is
published by the Dallas Remote
Imaging Group, 4209 Meadowdale
Drive, Carrollton, TX 75010 USA. Several copies perused in our office indicate that this newsletter contains a
high level of quality information.
Further reading
(1) "High Resolution Weather Satellite Pictures," M. L. Christieson, Wireless World December 1981 and January 1982.
(2) "Tracking Low Earth Orbit Satellites At LIS Band", "Break In" NZART
publication, March 1989.
Acknowledgment
I would like to thank Mr Brian Buckingham and Mr Fred Lehner for their
time and assistance in supplying background information.
SC
MAY 1992
87
July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid; Booster For TV &
FM Signals ; Th e Discolight Light Show, Pt.1; Tone
Burst Source For Amplifier Headroom Testing ;
What Is Negative Feedback, Pt.3; 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
01 Nicad Batteries; Data On Insulated Tab Triacs.
September 1988: Hands-Free Speakerphone;
Electronic Fish Bite Detector; High Performance
AC Millivoltmeter, Pt.2; Build The Vader Voice ;
Motorola MC34018 Speakerphone IC Data; What
Is Negative Feedback, Pt.4.
October 1988: Stereo FM Transmitter (Uses
Roh m BA1404) ; High Performance FM Antenna ;
Matchbox Crystal Set; Electronic House Number;
Converting A CB Radio To The 28MHz Band ;
Queensland's Powerful Electric Locomotives.
November 1988: 120W PA Amplifi er Modul e
(Uses Mosfets) ; Poor Man's Plasma Display;
Automotive Night Safety Light; Adding A Headset
To Th e Speakerphone; How To Quieten The Fan
In Your Computer; Screws & Screwdrivers, What
You Need To Know ; Diesel Electric Locomotives.
December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1; Diesel Sound Generator; Car
Antenna/Demiste r Adaptor ; SSB Adaptor For
Shortwave Receivers ; Why Diesel Electrics Killed
Off Steam ; Index to Volume 1.
January 1989: Line Filter For Computers; Ultrasonic Proximity Detector For Cars ; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cassette Players; Massive Di esel Electrics In The USA; Marantz LD50 Loudspeakers.
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.
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.
June 1989: Touch-Lamp Di mmer (uses Siemens
SLB0586) ; Passive Loop Antenna For AM Radios; Universa l Temperature Controller; Understanding CA O Probes; LED Message Board, Pt.3.
March 1989: LED Message Board, Pt.1; 32-Band
Graphic Equaliser, Pt.1 ; Stereo Compressor For
CD Players; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Map reader
For Trip Calculations ; Electronics For Everyone Resistors.
Apri l 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know
About Capacitors; Telephon e Bell Monitor/Transmitter ; 32-Band Graphic Equaliser, Pt.2 ; LED Message Board, Pt.2.
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.
August 1989: Build A Baby Tower AT Computer;
Studi o Series 20-Band Stereo Equaliser, Pt.1 ;
Garbage Reminde r - A 7-Day Prog ramm able
Tim er; Introducti on To Stepper Motors; GaAsFet
Pream plifier For The 2-Metre Band ; Modern 3Phase Electric Locomotives.
September 1989: 2-Chip Portable AM Stereo
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Radio (Uses MC 13024 and TX7376P) Pt.1 ; AlarmTriggered Telephone Dialler; High Or Low Fluid
Level Detector; Simple DTMF Encoder; Studio
Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero
Module for Audio Amplifiers (Uses LMC669).
Protection Switch For Power Supplies; A Speed
Alarm For Your Car; Design Factors For Model
Aircraft; Fitting A Fax Card To A Computer; What
To Do When Your Computer Goes Bung, Pt.2.
TV; 4-Channel Lighting Desk, Pt.1; 13.5V 25A
Power Supply For Transceivers; Active Filter For
CW Reception; Electric Vehicle Transmission
Options; Tuning In To Satellite TV, Pt.1.
July 1990: Digital Sine/Square Generator, Pt.1
(Covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; Low-Cost
Dual Power Supply; Inside A Coal Burning Power
Station; What To Do When Your Computer Goes
Bung, Pt.3 ; Weather Fax Frequencies.
July 1991: Battery Discharge Pacer For Electric
Vehicles; CD Error Analyser, Pt.1; Loudspeaker
Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets,
Pt.2; Tuning In To Satellite TV, Pt.2; PEP Monitor
For Transceivers
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; What
To Do When Your Computer Goes Bung, Pt.4.
August 1991: Build A Digital Tachometer; Masthead Amplifier For TV & FM ; PC Voice Recorder;
Error Analyser For CD Players, Pt.2; Tuning In To
Satellite TV, Pt.3; Installing Windows On Your
PC; Step-By-Step Vintage Radio Repairs.
September 1990: Music On Hold For Your Telephone; Remote Control Extender For VCRs;
Power Supply For Burglar Alarms; Low-Cost 3Digit Counter Module; Simple Shortwave Converter For The 2-Metre Band.
September 1991: Studio 3-55L 3-Way Loudspeaker System; Digital Altimeter For Gliders &
Ultralights, Pt.1; Build A Fax/Modem For Your
Computer; The Basics Of AID & D/A Conversion;
Windows 3 Swapfiles, Program Groups & Icons;
How Glass-Mount antennas Work.
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.
October 1991: Build A Talking Voltmeter For
Your PC, Pt.1; SteamSound Simulator Mk.II; Magnetic Field Strength Meter; Digital Altimeter For
Gliders & Ultralights, Pt.2; Getting To Know The
Windows PIF Editor.
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 6Metre Amateur Transmitter.
November 1991: Colour TV Pattern Generator,
Pt.1 ; Battery Charger For Solar Panels; Flashing
Alarm Light For Cars; Digital Altimeter For Gliders
& Ultralights, Pt.3; Build A Talking Voltmeter For
Your PC, Pt.2; Error Analyser For CD Players
Pt.3; Modifying The Windows !NI Files.
December 1989: Digital Voice Board (Records
Up To Four Separate Messages); UHF Remote
Switch; Balanced Input & Output Stages; Data
For The LM831 Low Voltage Amplifier IC; Install
A Clock Card In Your PC; Index to Volume 2.
December H/90: DC-DC Converter For Car Amplifiers; The Big Escape - A Game Of Skill; Wiper
Pulser For Rear Windows; Versatile 4-Digit Combination Lock; 5W Power Amplifier For The 6Metre Amateur Transmitter; The Great Green CD
Pen Controversy; Index To Volume 3.
December 1991: TV Transmitter For VCRs With
UHF Modulators; Build An lnfrared Light Beam
Relay; Compact Solid-State Laser Pointer; Build
A Colour TV Pattern Generator, Pt.2; The Miracle
Piano Teaching System; Windows 3 & The
Dreaded Unrecoverable Application Error.
January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR ; Speeding Up
Your PC; Phone Patch For Radio Amateurs; Active Antenna Kit ; Speed Controller For Ceiling
Fans; Designing UHF Transmitter Stages.
January 1991: Fast Charger For Nicad Batteries,
Pt.1; The Fruit Machine; Two-Tone Alarm Module; Laser Power Supply; LCD Readout For The
Capacitance Meter; How Quartz Crystals Work;
The Dangers When Servicing Microwave Ovens.
January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V 8A Power Supply, Pt.1; Baby Room
Monitor/FM Transmitter; Automatic Controller For
Car Headlights; Experiments For Your Games
Card; The GPS Satellite Navigation System.
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. ·
February 1991: Synthesised Stereo AM Tuner,
Pt.1; Three Inverters For Fluorescent Lights; LowCost Sinewave Oscillator; Fast Charger For Nicad
Batteries, Pt.2; How To Design Amplifier Output
Stages; Tasmania's Hydroelectric Power System.
February 1992: Compact Digital Voice Recorder;
SO-Watt/Channel Stereo Power Amplifier; 12VDC/
240VAC 40-Watt Inverter; Adjustable 0-45V 8A
Power Supply, Pt.2; The Mobile Telephone Revolution; Designing A Model Speed Controller.
March 1990: 6/12V Charger For Sealed LeadAcid Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16Channel Mixing Desk, Pt.2; Using The UC3906
SLA Battery Charger IC.
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
The Config.Sys & Ansi.Sys Files.
March 1992: TV Transmitter For VHF VCRs; Studio Twin Fifty Stereo Amplifier, Pt.1; Thermostatic
Switch For Car Radiator Fans; Telephone Call
Timer; Updating The Resistor/Capacitor Scene;
Coping With Damaged Computer Directories.
October 1989: Introducing Remote Control ; FM
Radio Intercom For Motorbikes (Uses BA 1404 &
TDA?000) 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 Wireless Microphone; 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.
April 1990: Dual Tracking ±50V Power Supply;
VOX With Delayed Audio ; Relative Field Strength
Meter; 16-Channel Mixing Desk, Pt.3; Active CW
Filter For Weak Signal Reception; How To Find
Vintage Radio Receivers From The 1920s.
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; 16-Channel Mixing
Desk, Pt.4; What To Do When Your Computer
Goes Bung, Pt.1.
June 1990: Multi-Sector Home Burglar Alarm ;
Low-Noise Universal Stereo Preamplifier; Load
April 1991: Steam Sound Simulator For Model
Railroads; Remote Controller For Garage Doors,
Pt.2; Simple 12/24V Light Chaser; Synthesised
AM Stereo Tuner, Pt.3; A Practical Approach To
Amplifier Design, Pt.2; Playing With The Ansi.Sys
File ; FSK Indicator For HF Transmissions.
May 1991: Build A DTMF Decoder; 13.5V 25A
Power Supply For Transceivers; Stereo Audio
Expander; Fluorescent Light Simulator For Model
Railways ; How To Install Multiple TV Outlets, Pt.1 ;
Setting Screen Colours On Your PC.
June 1991: A Corner Reflector Antenna For UHF
April 1992: lnfrared Remote Control For Model
Railroads; Differential Input Buffer For CROs; Studio Twin Fifty Stereo Amplifier , Pt.2; Understanding ComputEl,r Memory; Switching Frequencies in
Model Speed Controllers; Aligning Vintage Radio
Receivers, Pt.1.
PLEASE NOTE: All issues from November 1987
to June 1988 are now sold out. All subsequent
issues are presently in stock. For readers wanting
articles from sold-out issues, 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.
MAY 1992
89
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.
Transistor
replacements
On the Brake Light Flasher Circuit
(described in the April 1989 issue of
SILICON CHIP), is there another transistor I can use instead of the BD645?
I have catalogs from Altronics, Rod
Irving, Dick Smith Electronics and
Jaycar, and none of them list BD645.
And in Fig. 2 of the article on the
Car Antenna Adaptor (SILICON CHIP,
December 1988), the photo shows two
wires that come from the power to the
circuit board, with (+)going to L2 and
(-) is going to L1, but on the other side
of the toroid it shows L1 going to (+),
and L2 going to(-). Does it make any
difference which wires go to the demister?
Also in the text it specifies that the
75-ohm cable should have a 1.25mm
central core. Most ofmy catalogs don't
list the sizes of the central core of
their 75-ohm cable and the largest
size that is stated is 0. 95mm from
DSE. Where can I get 75-ohm cable
with a 1.25mm central core?
Finally, the toroid core is specified
as Neosid 28-042-31 F14 ferrite but I
can't find that part in any of the
Remote control
extender
I have constructed the remote
control extender published in the
September 1990 issue of SILICON
CHIP but I have been unsuccessful
in getting it to operate. The indicating LED does light up when the ·
remote controller of the VCR is
operated, however the signal is not
being received at the VCR end.
Can you please help me with
the following questions:
(1) What should the output..voltage at pin 9 of the SL486 be when
high? Using a multimeter, the voltage is 200m V when low and varies
little when high. From data sheets,
90
SILICON CHIP
catalogs I have. The closest I can find
is a toroid core, size OD 44 x ID 24 x H
16.5mm, which is the type I bought.
(O. M., Liverpool, NSW.)
• In the Brake Light Flasher project
you can replace the BD645 transistor
with a BD649, which is available from
Altronics in Perth for $2.65. This transistor is virtually identical to the
BD645 except that it has a higher voltage rating.
For the Car Antenna Adaptor project, we haven't tried the toroidal core
you mentioned in your letter, however as the application is not all that
critical, we cannot see why it wouldn't
work.
You can substitute 50-ohm coaxial
cable for the 75-ohm type. A suitable
type would be Dick Smith Cat. W2099. It does not make any difference
which wires go to the demister.
Current rating for
solar battery charger
I am after some more information
concerning the "Battery Charger for
Solar Panels" that appeared in the
November 1991 edition.
I am considering using the charger
this voltage should be Vee (the
supply voltage). I replaced this
chip and the same results occurred.
(2) What should the voltage be
at the receiving end; ie, at the infrared LED?
(3) The BPW50 chip has been
replaced by a BP104. Is this OK?
Your help would be appreciated.
(B. M, Rockhampton, Qld).
• The BPW50 can be replaced by
a BP104 but you have replaced
the SL486 unnecessarily as it was
probably behaving normally. Some
constructors are having low sensitivity problems with this unit.
When re-transmitting an infrared
remote control signal, the red acknowledge LED flashes to indicate
with an SLA battery but one that requires a float voltage ofbetween 13.6V
and 13.8V for standby use. It is intended to connect the charger's input
to an automotive electrical system.
The SLA battery I have draws a
peak current of around 2A, which
quickly dies away to a fraction of this
as the battery charges. I wish to know
the maximum continuous and maximum peak current the charger can
supply, as this information does not
appear anywhere in the article. I
would also like to see a graph of load
voltage against load current.
Apart from this omission, the circuit would seem to be ideal for the
intended application and, with the
addition of a constant cur:..ent sink,
could be used to charge nicads while
in a mobile environment (eg, battery
packs for hand held radios).
Your thoughts and ideas on this
application for the charger would be
greatly appreciated. (W. ·S., Endeavour Hills, Vic).
• The capacity of the circuit is about
2A, although this will depend more
on the solar panel than the circuit
components. It should be suitable for
your SLA battery. It could also be
reception of this signal, as you have
found. However, the infrared LED
(IRLED1) may not provide a satisfactory output for some or all of
the remote control functions.
This problem is caused by IC1 's
AGC attack time being too short
when used with some infrared remote controls. To solve this problem, the 0.15µF capacitor at pin 8
of ICl.should be changed to a larger
value. Some experimentation may
be required to find the best value,
which should be in the range from
6.8µF to 22µF (use an electrolytic).
The positive terminal of the capacitor connects to pin 8 of IC1
and the capacitor should be rated
at 16VW or higher.
used for nickel cadmium batteries provided you included a timer or some
other means to avoid overcharging.
Exhaust gas analyser
would be a good project
I am writing to enquire whether or
not you may have considered publishing an exhaust gas analyser in your
magazine. As a motoring enthusiast
who likes to work on my own car, I
often have wished for an exhaust gas
analyser to set the mixture on the
carburettor but sadly, commercial
units cost many hundreds of dollars.
These electronic units use infrared
pickup devices, calibrated accordingly, or "hot wire" resistance devices.
Perhaps even the sensing device in
the exhaust gas detector project published in the July 1989 issue could be
used? I'm sure this project would be
very popular, as digital tacho/dwell
projects for cars have been very popular too. (S. L., North Balwyn, Vic).
• It would be relatively easy to develop a suitable circuit and, as you
suggest, it could be based on a semiconductor gas sensor similar to that
used in the exhaust gas detector featured in the July 1989 issue of SILICON
CHIP.
The big problem is how to calibrate
the circuit. It must either be calibrated
in a standard gas mixture or against a
standard gas analyser. We don't have
the solution to this problem, otherwise we would have published the
circuit already.
Improvements to the
SLA battery charger
I'd like to make a suggestion concerning Darren Yates' Sealed Lead
Acid Battery Charger in the March
1990 issue. This turned out to be a
terrific charger after ironing out some
bugs: (1) figuring out the way voltage
select switch S3 is hooked up; and (2)
figuring out why the charge state LEDs
would not behave.
The person I assembled this charger
for raised the possibility of damage to
the charger through leakage from the
battery when the unit was switched
off with the battery still connected. I
had a 24V relay lying around, so I
connected the coil to the 24V DC that
enters the board and the 'normally
open' contacts to the positive lead
running to the battery being charged.
Sports coil does not
give better spark
I have built the High Energy Ignition System described in the
Ap:dl 1988 issue of SILICON CHIP.
On two occasions now it has failed.
On the first occasion it blew the
Dadington transistor, the IC and
one of the polyester capacitors. On
the second occasion, all the zener
diodes had gone short circuit.
Is there anything wrong with the
design? My friend seems to think
that it is because I am using a
sports coil rather than the original
coil fitted to the car. (A. K., Haberfield, NSW).
• Your friend is dead right. If you
use a sports coil with this circuit,
you are bound to blow it up sooner
or later. Because of the inbuilt
dwell extension, the High Energy
Ignition circuit causes consider-
Thus, when the unit is off, the battery
is isolated.
This proved to be most effective
and I intend to use it on all applicable
projects in the future, as an additional
safety feature to augment any diodes
used for this purpose.
The last point I'd like to make about
this project is the mains switch only
switching the Active line. Since the
switches supplied with most kits are
DPDTs, why not switch both Active
and Neutral for safety? (P. B., Epping,
NSW).
• In view of some recent feedback on
this project, we are looking to revise
the circuit and present it again some
time later this year. The main problem seems to be associated with the
wiring of the switches and the use of
LF347s as comparators but otherwise
the original circuit was quite practical.
There is no need to provide relay
isolation, as the existing diodes in the
circuit provide this feature.
As far as the mains switching is
concerned, there are no real advantages in switching both Active and
Neutral, although we have on occasion used DPDT mains switches. On
the one hand you can say that if Active and Neutral switching is included,
the appliance will definitely be off
when switched off.
ably more current to flow through
a standard ignition coil, thereby
increasing available spark energy.
A sports coil also draws considerably more current when fitted to
a standard Kettering ignition system. Fitting a sports coil to an electronic ignition system with dwell
extension is just asking for trouble
as the current will be increased
even further. No wonder you blew
the Darlington transistor.
The High Energy Ignition circuit gives more than enough spark
energy with a standard coil. The
only possible result of fitting a
sports coil to it, apart from eventually blowing the system up, is that
the spark plugs would be more
quickly eroded and ultimately,
would have to be replaced more
often.
Need we say more? Don't use a
sports coil!
However, we still regard the only
safe mains appliance to work on as
one with the mains plug pulled out of
the wall socket. On the other hand, if
only the Active is switched, the mains
wiring is simpler and there are less
chances of mistakes.
Questions on
amplifier design
My questions concern the articles
published in February and April 1991,
"A Practical Approach to Amplifier
Output Stage Design".
With regards to the output stages,
can more transistors (for each part of
the amplifier) be connected in parallel to help provide more collector current? From what I can gather, this is
used extensively in car amplifier design and surely beats having to use •
TO-3 transistors (although they may
handle a lot of power, they take up a
lot of space, and their construction
makes it harder to use fan cooling).
A large number of car amplifiers
use up to 14 transistors in each channel, and maintain a relatively small
case. The author, David Eather, talks
about transistors in common collector mode, and using emitter resistors
for equal current sharing. Is the above
essentially what he means?
David Eather also discusses the use
MAY 1992
91
Pulse current
inIRLEDs
With the infrared lightbeam relay published in the December
1991 issue, how was the value of
the 15Q resistor in series with the
LEDs calculated; ie, what were the
values of forward voltage across
the LEDs and what value of current was used?
Also, can the infrared emissions
be focussed with lenses and woµld
the point of focus be much different to that of red light? In the same
issue of SILICON CHIP there was a
TV transmitter for VCRs. The output impedance of the transmitter
was quoted as 75 ohms. Is this
determined by L2 and the 220pF
capacitor or is this a characteristic
of the OM350? (D. A., Findon, SA).
• The 15Q resistor in the light
beam relay circuit was selected to
give a peak current through the
LEDs of between 300 and 400mA.
Thi& gives a forward voltage across
each LED of about 1.8V. The LEDs
are able to pass a maximum repetitive peak current of 1A but only at
very short duty cycles. Our circuit
meets those requirements.
You could focus the infrared
light with lenses and thereby improve range and sensitivity. The
point of focus would be little different to that for red light.
As far as the TV transmitter is
concerned, the output stage of the
OM350 is designed to drive 75ohm loads. Its actual output impedance is, of course, much lower.
of Mosfets in the output stage. Are
ciated. (B. M., Giralang, ACT.)
these similar to using bipolar transis• It is common practice to parallel
tors? We covered Mosfets in electronoutput transistors to obtain greater
ics as a "basic idea" course and from
current capability in the output stages
what I can see, they are a totally difof amplifiers. We have done this sevferent "can of worms".
eral times with amplifiers published
Any information on how these tran- in SILICON CHIP, the most recent exsistors are used in amplifier circuits
ample being the 50 watt per channel
would be greatly appreciated. Will
stereo module featured in the Februthe driver transistors be affected by ary and March 1992 issues.
the extra transistors used to handle
The limit on how many output tranincreased collector current and if so,
sistors can be connected in parallel is
how can this be remedied? Can the
set by the current capability of the
DC-DC circuitry use this same techpreceding driver transistors but some
nique , so that it can handle increased big commercial amplifiers we have
current, in both the oscillator transisseen have had as many as six output
tors (the final stage) and the DC regu- transistors in parallel, making a total
lator?
of 12 output transistors. Emitter resisDo transistor SOAR curves follow a tors are used to improve current sharing but the transistors need to be reahyperbolic function, with the limits
being their maximum Vee and le?
sonably well matched even so.
When I was poking around in my
Mosfets are a different ballgame
mother's car one day, I noticed that
since they are transconductance dethe back shelf had provision for three vices (ie, amps controlled by volts).
6 x 9-inch speakers and not long after, We featured an amplifier with Mosfets
I thought of designing a circuit which in the output stages in our November
would split a stereo signal into three · and December 1988 issues.
channels: left only, that which is comThe SOAR (safe operating area)
mon to both channels and a right only curve of a power transistor represents
channel.
a power derating at higher voltages
There was a stereo enhancer project and as you have correctly surmised,
(ETI-1405) which worked in a similar the curve is a hyperbola but with a
manner..Instead of subtracting the censteeper slope than the hyperbola
tre, L and R are isolated and added
drawn from the transistor's nominal
power rating.
back later on.
Any help with the questions I have
We note your comments about car
presented here will be greatly appreamplifiers using large numbers of tran92
SILICON CHTP
sistors. However, car amplifiers do
not just parallel a lot of output transistors to get sufficient power as this
approach would still not give adequate
power into loudspeakers with a nominal impedance of four ohms, or even
two ohms. Commonly, car amplifiers
use two amplifier stages in each channel and these drive the speakers in
bridge mode. This means the maximum voltage to the speaker is doubled and hence the power is quadrupled (in theory).
The bigger car amplifiers also incorporate a DC-DC inverter to boost
the supply up and thus enable much
more power to be developed.
We are not keen about your 3-channel circuit concept. It really is not
necessary. All stereo recordings have
a substantial amount of signal common to both channels and since this
is reproduced by both speakers, it
avoids any "hole in the middle effect".
How to magnetically
shield loudspeakers
How do you magnetically shield a
loudspeaker case to stop it affecting
the television nearby. (I hope to sit the
TV on a homemade subwoofer enclosure). Keep up the great magazine! (H.
P., San Remo , Vic).
• As far as magnetically shielded
loudspeakers are concerned, it is not
the case or the chassis which needs
shielding but the ferrite magnet. This
is shielded, during manufacture, by a
steel cup which i.s fitted over the magnet. In the 2ase of the more sensitive
speakers with a bigger magnet structure, an additional magnet is interposed between the steel cup and the
main magnet, to help cancel out any
leakage field.
We think that it would be difficult
to satisfactorily shield an existing
speaker unless you had the correctly
designed hardware.
Notes & Errata
TV Transmitter for UHF VCRs, March
1992: the 12V supply connections
shown on the overlay diagram of page
18 are reversed. Also the photo of the
underside of the transmitter board is
for the version described in December 1991. The components on the copper side of the board are not used in
the UHF version.
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Dr. Nikola Tesla - Complete Patents ...... $93
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80287-12
80287-20
80387SX20
80387IX33
80287XLT
Intel
AMO
IIT
IIT
IIT
Intel
EXPANSION CARDS
$130.00
$105.00
$130.00
$168.00
$250 .00
$150.00
DRAM
1Mbx4
1Mbx4
1Mbx4
1Mbx 1
414256
41256
41256
41464
4164
"-
r
Allow 15 weeks for delivery of some items.
Payment can be made by cheque made out
to Plough Book Sales, PO Box 14, Belmont,
Vic. 3216. Phone (052) 661262.
Hercules, EGA & VGA cards respectively. $35. *** "SATFAX" $45 is a NOAA,
Meteor & GMS weather satellite picture
receiving program. Uses EGA & VGA
modes, needs EGA or VGA colour monitor & card, plus "WEATHER FAX" PC
card. $45. *** All programs are on 5.25inch or 3.5-inch discs (state which) &
include documentation. Add $3 postage. Only from M. Delahunty, 42 Villiers
St, New Farm, 4004 Old. Phone (07)
358 2785.
"I
MEMORY, DISKS & PROCESSORS
~
St Zip
PgZip
Pg Dip
80ns
80ns
100ns
80ns
80ns
100ns
$30.00
$30.00
$30 .00
$5 .75
$6.80
$1.90
$2.00
$2.60
$2.50
PELHAM
TOSHIBA LAPTOP
T1000SE
T1600
T3100E
T3100SX
T3200
T5100
T5200
2Mb
2Mb
2Mb
2Mb
3Mb
2Mb
2Mb
$265.00
$145.00
$145.00
$145.00
$236.00
$145.00
$155.00
LCS 866IN (AT) EMS
512-32Mb (SIMMS) OK $240.00
BOCARAM AT PLUS
OKTO 8Mb
$240.00
BOCARAM AT
OK TO 2Mb
$180.00
BOCA PS2 MCA
OK TO BK
$180.00
($60 per Mb)
COMPAQ
386-20, 386-25,386-20S, 386-S,
386-33
4Mb modules
$345.00
4Mb boards
$400.00
Sales Tax 20%. Overnight delivery. Credit cards welcome.
1st Floor, 100 Yarrara Road (PO Box 382), Pennant Hills 2120.
Tel (02) 980 6988 Fax (02) 980 6991
"
UNIDEN SCANNERS
DON'T PAY MORE!
50XL RRP $299.95. Our price $211
10 memories, Lo-Hi VHF, UHF
10OXLT RRP $449.95. Our price $409
100 memories, Lo-Hi VHF, Air, UHF
200XLT RRP $549.95. Our Price $477
200 memories, Lo-Hi VHF, Air, UHF,
800 MHz
All prices include delivery.
Phone anytime today1
(03) 883 9535; Fax (03) 432 0716
~
DIGI-CART DSP BOARD
For 16-bit IBM compatibles. Broadcast quality 44.1 kHz/16 bit stereo
audio with audio recorder software.
$1599 + Tax
Custom software service for applications available.
PC Computers (08) 332 6513
36 Regent St Kensington SA
TopCom Communications
PO Box 336, Greensborough, Vic 3088.
~
TRANSFORMER REWINDS
ALL TYPES OF TRANSFORMER REWINDS
TRANSFORMER REWINDS
- Reply Paid No.2, PO Box 438, Singleton, NSW
2330. Ph: (065) 761291 . Fax: (065) 761003.
Direct CAD PCB design
from your schematic, rough
PCB,to ink plot negative
for prototype or one-off in
sing I e or doub I e sided with
s ii k screens & .so I der resist.
NC and photoplot options
avai I able on floppies.
7
Phone <02)807 6916
or wr I te
0 ~ ~ .C ~ G . F . & M . Hugfies
~ PO Box 37, Ryde
PCB ART
NSW, 2112
0 JO
-
laser diode assemblies (collimator pens),
$35; 1OnF/3kV disc ceramics, 10 for
$12; used regulated 15kV 5OOµA EHT
power supplies, $45; 1mW 800nm IR
LEDs at 10 for $3.50. Oatley Electronics, PO Box 89, Oatley 2223. Phone
(02) 579 4985. Fax (02) 570 7910.
quantity prices. Limited supply. Oatley
Electronics, PO Box 89, Oatley, NSW
2223. Phone (02) 579 4985. Fax (02)
570 7910.
NEW CRO TUBES & VALVES: 1-inch
electrostatic deflection, type number
CV1522 - $35; 3-inch spiral PDA electrostatic deflection, type numbers DP1O-6 and 4VP7 - $44; 3-inch magnetic
deflection (no yoke supplied) PDA, type
numberCV223O-$25; mercury vapour
rectifier value, type 866A/866-$5; pentode valve, type 6C6 - $5. All items in
original cartons. Enquire about reduced
INFRARE;D NIGHT VIEWER: Not a
complete kit but just the absolute essentials- an IR image converter tube and a
ready-made power supply. The supply
has approximate dimensions of 105 x
56 x 37mm, draws approx. 35mA from a
9V battery, and can power any IR tube.
The tube may have some blemishes but
will function properly. Basic instructions
are provided. Give-away at $150 for the
MAY 1992
95
r-------------------------,
l
SILICON CHIP BINDERS
These beautifully-made binders will
protect your copies of SILICON CHIP.
They feature heavy-board covers and
are made from a distinctive 2-tone
green vinyl that will look great on your
bookshelf.
Advertising Index
Adilam Electronics ........ ..... ...... IFC
All Electronic Components ........ 71
Altronics .... ....... ........ .......... .. 72-75
Antique Radio Restorations .. .... 94
Av-Comm ....................... ........ ... .. 8
Breakthrough Electronics ... .. ..... 25
* High quality.
* Hold up to 14 issues
David Reid Electronics ... ............. 3
Dick Smith Electronics ...... 9,27-29
* 80mm internal width.
Emona Instruments ................ ... 55
Geoff Wood Electronics .............. 5
* SILICON CHIP logo printed in gold-
G. F. & M. Hughes ................ .... . 95
coloured lettering on spine & cover.
Harbuch Electronics ............... ... 42
Yes! Please send me ____ SILICON CHIP binder(s) at $A11.95 plus
$A3 p&p each (NZ $A6 p&p).
Hycal Instruments ............. ... 25,94
Enclosed is my cheque/money order for $_ _ _ _ or please debit my
Jaycar Electronics ................ 45-52
□ Bankcard
O Visa Card
lcom Australia .. .... ...... .... ... ...... IBC
J.V. Tuners .... .. .. ........................ 42
O Master Card
Mark One Communications ..... . 39
Oatley Electronics .. .. ....... ... .. 57,95
Card No.
L_____L_L___j____JI I~ '----'--'--..JI I~ L___j____J'-----.. JI ~I
'---..J'-----..- - '
PC Computers .............. ... .. .... ... 95
PC Marketplace ... ... ... .. ....... ...... 21
Signature._ __ _ _ _ __ _ _ _ _ Card expiry date._ _ _ /_ __
Pelham ... .... .... ................... OBC,95
Name _ _ __ __ _ _ __ _ _ __ _ _ _ _ _ _ _ _ __
Peter C. Lacey Services ........... 40
Plough Book Sales .. ... ............... 95
Street
- - - - -- - -- - - -- - -- - - - -- - - -
Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ _ _ __
Preston Electronics ................... 56
Protel Technology ... .................. 39
RCS Radio ... ............................. 54
Resurrection Radio .... .. .... ......... 71
SILICON CHIP PUBLICATIONS
PO Box 139, Collaroy Beach, NSW 2097, Australia.
Phone (02) 979 5644
Fax: (02) 979 6503.
L _________________________ J
Rod Irving Electronics .. .... .... 10-15
Rolec Pty Ltd .. .... .... .............. 66-67
Silicon Chip Back Issues ..... 88-89
Silicon Chip Binders ....... ........... 96
St Lucia ....................................... 7
pair. 75mm perspex IR filter, $16. Major
cards accepted with phone & fax orders. Certified p&p for any or all the
listed items: Australia $5; NZ (airmail)
$10. Oatley Electronics, PO Box 89,
Oatley, NSW 2223. Phone (02) 579
4985. Fax (02) 570 7910.
Circuit Ideas Wanted
Do you have a good circuit idea
languishing in the ol ' brain cells? If
so, why not sketch it out, write a
brief description & send it to us
We'll pay up to $60 for a really
good circuit. So transfer your circuit to paper & send it to Silicon
Chip Publications, PO Box 139,
Collaroy Beach, NSW 2097.
96
SILICON CHIP
WANTED
TECS Electronics & Computers 61
Transformer Rewinds ... ........... .. 95
PERSON TO REPAIR Macintosh 512K
power supply fault. Phone (03) 398 2486
(Bus) or (03) 742 6093 (AH) .
TopCom Communications ........ . 95
CIRCUIT/MANUAL for
Printed circuit boards for SILICON
CHIP projects are made by:
PC Boards
National
NV450A video recorder, TC2252 CTV.
Phone (077) 72 8572 BH, (079) 52 3737
weekends.
DISTORTION TEST SET wanted to
buy. Must be auto-nulling and with instruction manuals. Can be Audio Precision , Sound Technology 170x, Hewlett
Packard 339 or equivalent standard. If
you have one to sell, please contact Leo
Simpson on (02) 979 5644 with details
and price.
• Jemal Products, 5 Forge St,
W~lshpool, 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.
SONY:
SONY:
LQQK
LQQK
PARENTS
PARENTS
ILLUSTRATED •
D ENCYCLOPEDIA
·
11
I)
n
LANGUAGES OF •
Iii THE WORLD
Why pay $1000's for books? Buy an
entire educational centre plus so
much more for $1140.
NATIONAL GEOGRAPHIC
~
~
Not only can this fantastic software package
educate you and your children, it also can
provide hours of entertainment. Learning can be
difficult for many people, but with Interactive
Educational Software, you interact with the
computer, ask questions and watch the answers.
Info on 200 animals, photos, range maps, motion
clips essays and 155 animal vocalizations.
rA MIXED-UP
1M
The World Atlas brings the entire globe to your
computer screen. This atlas, almanac and world
fact book in one, gives you instant access to over
240 fully detailed, EGA/VGA colour maps and a
huge database of international information.
n
MICROSOFT
~
1111 REFERENCE LIBRARY~
'. .
- GREAT FOR STUDENTS-
MOTHER GOOSE*
An interactive game designed to stimulate your
child's imagination with full colour graphics and
digitized sound, voices and music.
WhatCDRoms
are available?
-
The perfect reference tool for
travellers, educators, business
people, librarians and students of all
ages.
•
D SOCIETY'S MAMMALS*
WORLDATLAS*
1
A program which translates to and from Chinese,
Danish, English, Finnish, French, German,
Italian, Japanese, Norwegian, Spanish &
Swedish. Allows retrieval of translations,
dictionary entries and synonyms & then export
to WP packages(Chinese and Japanese display
only). Includes the full text of 18 dictionaries in
12 languages.
Compton's Encyclopedia (from Brittanica)
contains full text of 26 volumes, 9 million words,
32,000 articles, 1500 illustrations including
sound and speech recording. Forget flipping
through volumes, instead, follow key pathways
on words and subjects - access information in
the blink of an eye.
Not only is this Software
Educational - It's fun too!
· ,·
This indispensable collection of reference
materials includes the American Heritage
Dictionary, Roget's II Electronic Thesaurus, the
World Almanac and Book of Facts, Bartlett's
Familiar Quotations, and more- all on a single
CD-ROM disc. Fm added efficiency, all reference
volumes interface directly with more popular
word processing programs.
Over 1000 Rom products are available including
SUBJECT
ACCOUNTANTS
AEROSPACE
AGRICULTURE
ART
BIBLE STUDY
BIOLOGY
BIOMEDICINE
CARDIOLOGY
CHEMISTS
CHESS
CINEMA
CIVIL ENG
COMPUTERS
DESKTOP PUBLISHING
ELECTRICAL ENG .
ENVIRONMENT
GEOGRAPHY
GEOLOGY
HISTORY
HORTICULTURE
TITLE
- Oiskrom Tax Law Database
- Aerospace Database
SUBJECT
LAW
LIBRARY
-Agricola
- Coafe's Art Review Impression ism
- CD Word/The Bible Library
- Biological Abstracts
-Bibliomed
- Bibliomed Cardiology Series
- Excerpta Medica - Drugs &
Pharmacology
- Chess Datarom
-Cinescan
- Citis CD-ROM
- Carousel/C-CD ROMiComputer Select
- Clip Art (Various)
- FT Business Graphics
- lnspec On Disc.
- Environme ntal Library
- Countries of The World
-Geovision Windows on the World
- The Middle East Diary
- The Plant Doctor
MEDICINE
MUSIC
NURSING
OCEANOGRAPHY
PATENTS
PEOPLE
SCIENCE
SPACE
TRAVEL
VETERINARY
WILDLIFE
GENERAL
TITLE
- Case Law, NSW, SA, TAS & VIC
- Books in Print PlusfBNB on CD Rom
- Business Periodicals
- Cancer on DiscfConsult Medical
-Posindex
- Music Library Sound Recordings
-Nurses Medical Partner
- Aquatic Science
-Automated Patent Search (us·
- Biography Index
·
- Applied Science Library
- Nasa Space Encyclopedia
- Great Cities Of The World
- The Merck Veterinary Manual
- Wildlife & Fish Worldwide
-Australia On a Disk
- Best Encyclopedia-Grolier
- Business Periodicals on Disk
- Facts on File 1980-90
- Guinness Book of Records
-Jane's All The World's Aircraft
-Oxford English Dictionary
~-----------------~
COMPUTER REQUIREMENTS
XT/AT Compatible, 512 Ram. DOS 3.1 or above
hard disk drive.
Recommended
VGA Monitor & VGA adapter
Mouse
*Requires VGA
(For PS2 MCA I/F card add $320)
PACKAGE CONTENTS
Sony external drive model CDU 7205U (which
supports CD Rom mode 1 & 2 & Audio
combined CD)
Sony bus interface card (half card value $180)
Software Collection (as detailed)
PELHAM PTY LTD
1st Floor, 100 Yarrara Road, Pennant Hills 2120
Ph (02) 980 6988 Fax (02) 980 6991
|
