July 1992 - Silicon Chip Online

Outer Front Cover
Contents
Publisher's Letter: When will domestic appliances be quiet?
Vintage Radio: Unusual problems lead to interesting repairs by John Hill
Feature: Understanding The World Of CB Radio by Herb Zallner
Project: Build A Nicad Battery Discharger by Marque Crozman
Project: 8-Station Automatic Sprinkler Timer by Graham Blowes
Serviceman's Log: How do you get to blast a ghetto by The TV Serviceman
Order Form
Project: Portable 12V SLA Battery Charger by Darren Yates
Project: An Off-Hook Timer For Telephones by Darren Yates
Feature: Computer Bits by Paul Lynch
Feature: Amateur Radio by Garry Cratt VK2YBX
Project: Multi-Station Headset Intercom; Pt.2 by Marque Crozman
Feature: Electronics Workbench For Home Or Lab by Leo Simpson
Market Centre
Advertising Index
Outer Back Cover

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Understanding The World Of CB Radio AUSTRALIA'S DYNAMIC _ ~ ELECTRONICS MAGAZINE~ SERVICING - VINTAGE RADIO - COMPU:TERS - AMATEUR RADIO - PROJECTS TO BUILD ~ · ·; Tillll: >!'<,ii,_,_ ~ .,i. Eigh t Station if> .,ij.; Sprinkler Controller ~ 1L :~~:,:;· , ""'"" .J T ':;~~-::'.,__J """ fl ,._:, l,?I ~ • • • • • • • 1 a • e • • • ••. • ~ * Electronics Workbench For Home or Laboratory * Off-Hook Timer For Telephones * Amateur Radio * Serviceman's Log * Vintage Radio * Computer Bits SCOPEMETER The next generation of hand-held instruments ' e PHILIPS FLUKE® Its a 50MHz bandwidth Digital Storage Scope plus ... Full 3000 count DMM • • • • • • • 25MS / s dual channel digital storage 8-bit, 25 levels/div vertical resolution 7ns rise time, 40ns glitch capture lOns/div to 5s/div timebase Stores 8 waveforms (95 & 97) and 10 set-ups (97) Measuring cursors (95 & 97) "Auto-Set" automatic set-up of parameters, e.g. volts/div, time per div and triggering for any input signal • Functions include Min/Max recording, Touch Hold™. Relative and Percentage values. Autoranging etc e dBm. dBV and dBW (95 & 97) Simultaneous display of waveform and DMM functions ... • 5 Soft Keys for commands via pop-up menus • 12cm, 240x240pixel Super Twisted Nematic LCD screen • Fast reaction microprocessor control with extensive use of ASICs for low power consumption and high bandwidth • Floating high voltage measurements up to 600Vrms • Optical RS-232 Port for waveform plots, modem connection, set-up data, on-screen waveform comparison, field diagnostics and recalibration (97) • Low Power - 5W(typ) from NiCads, alkalines or car battery etc (4 hr internal battery) • Built-In component and baud rate testers and a sine, square and ramp signal generator (97) • Measures 47xl30x260mm, weighs 1.5kg Model 93 Basic instrument $1460 ex tax $1752 inc tax Model 95 Adds measuring cursors and recording function $1895 ex tax $2274 inc tax Model 97 Adds waveform and set-up memories, back-lit LCD, generator functions, RS-232 interface $2350 ex tax $2796 inc tax We also stock thefull range of Fluke Multimeters including the new Fluke 70 Series II with prices as low as $125 ex tax. Ask for our FREE 16 page Shortform Catalogue Special account facilities available for Education and Government Departments Express delivery throughout Australia and South Pacif'rc Detailed brochures and spec(fications available. We are factory trained to advise on your requirements for general purpose Test & Measuring Instruments <at>IIDII&1r ~1rW lli1f)]) 129 Queen Street, Beaconsfield P.O.Box 37 Beaconsfield NSW 2014 Tel: (02) 698 4776 Telex: AA71958 Fax: (02) 699 9170 OLD : Electro Technical Systems Old, Tel (07) 356 2699, Fax (07) 356 0456 Vo/.5, No.7. July 1992 FEATURES 16 Understanding The World Of CB Radio by Herb Zallner The background, the frequencies & the gear 82 Electronics Workbench For Home Or Lab by Leo Simpson ARE YOU HAVING battery problems with your hand-held telephone? This simple device will correctly discharge a nicad battery pack so that it can then be recharged to full capacity. Details page 22 Build it & clean up your work practices 4!i PROJECTS TO BUILD Eight Stal.ion Sprinkler Controller ~JI :' 22 Build A Nicad Battery Discharger by Marque Crozman Rids your batteries of the dreaded memory effect 30 8-Station Automatic Sprinkler Timer by Graham Blowes It can also control lights & other appliances 54 Portable 12V SLA Battery Charger by Darren Yates Recharge 12V SLA batteries from your car's lighter socket 64 An Off-Hook Timer For Telephones by Darren Yates Takes the phone off-hook & then replaces it after a preset time 76 Multi-Station Headset Intercom, Pt.2 by Marque Crozman Second article completes the construction details SPECIAL COLUMNS 6 Vintage Radio by John Hill Unusual problems lead to interesting repairs TAKE THE DRUDGERY out of watering your garden with this automatic 8-station sprinkler timer. It can also be used to control lights or other appliances. See page 30 40 Serviceman's Log by the TV Serviceman How do you get to blast a ghetto? 70 Computer Bits by Paul Lynch Good books on the PC can be well worthwhile 72 Amateur Radio by Garry Crutt PORTA8l!;; 12V SI.A BATTERY CHARGER Radiation hazards - the precautions you should take DEPARTMENTS 2 Publisher's Letter 4 Mailbag 53 Order Form 58 Circuit Notebook 74 Back Issues 85 Product Showcase 92 Ask Silicon Chip 93 Notes & Errata 94 Market Centre 96 Advertising Index YOU CAN USE THIS simple project to recharge 12V sealed lead acid batteries via your car's cigarette lighter socket. We show you how to build it starting page 54. JULY 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 Cratt, 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 publ ished 12 times a year by Silicon Chip Publications Pty 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 patents. 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 When will domestic appliances be quiet? Hands up all readers who spend some time every week doing domestic chores? Not many of you, are there? OK, I'll try another tack? How many readers have found that when domestic appliances are being used, they can hardly hear themselves think? Well most of you should be able to respond positively to the latter question. It is a fact that most domestic appliances are far noisier than they should be. Apart from power tools such as electric drills, circular saws and power planers, the noisiest domestic appliances are probably food mixers and processors. In my own home, whenever the food mixer is being used we have to shut it in the pantry cupboard - it is really deafening. It is so noisy that if it was a power tool used in industry, ear muffs would be mandatory. Many vacuum cleaners and hairdryers are not much better. If you vacuum clean an average size house at least once a week, you will know that it is a fairly strenuous task which is just made harder by all the noise. Most vacuum cleaners are so noisy in fact, that the average person using one will not be able to hear a phone ringing in the same room. The same applies to hairdryers and you aim most of the noise straight into your ears when using it. Washing machines are another unnecessarily noisy appliance. Virtually every household has one of these crude machines graunching away for hours every week. The cost of making the gearbox quieter would add very little to the purchase price. And a little anti-drum treatment to the inside of the panels would go a long way in silencing these beasts. Even appliances such as dishwashers and refrigerators which are supposed to be quiet can rarely said to be inaudible. In fact, while the newer fridges are generally more efficient , they are often noisier than models 15 or 20 years old. There is no real reason for all this domestic bedlam_.Appliances could be made a lot quieter. The problem is that few buyers ever enquire or ask for a demonstration of an appliance before they buy it. If most buyers did so, I am sure that a lot fewer noisy appliances would be sold. So if you are unhappy about the noise level of an appliance you've recently purchased, why not write a letter to the manufacturer or distributor about it? Make a bit of noise yourself. If enough people take action, the homes of the future will be quieter and more pleasant places to be in. Leo Simpson Mini DIN Plugs & Sockets Can't find any Mini DIN sockets ? 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Box Q103,SYDNEY 2000 Fax: (02) 261 8905 Postal Charges $5 - $25 " " "" ' $4.00 $26 - $50 ...... $ 6 .00 $51 - $ 100 ..... $ 7.00 $ 101 - $499 .. $9.00 $500 + ........... FREEi MAILBAG Too much emphasis on computers I find the magazine enjoyable and informative. The series of articles on electricity generation, electric railways, servicing electronic equipment, restoration of old radios and constructional articles have been very good and I hope that they and similar items continue. But I have a slight worry over the recent increase in articles to do with computers. I neither do nor intend to own a computer and thus my enthusiasm concerning their operation is less than that concerning other branches of electronics. Although I am reasonably competent in mathematics and physics, I find the computer mumbo-jumbo quite unintelligible. I began to read the article on computer memory (April p.7) but found so many untranslated and unexplained acronyms, jargon words (eg, "cache" means "hidden" in French, but what does it mean in computer jargon?). There seem to be enough computer magazines already available without SILICON CHIP adding to their number. Finally, although the "complaints " component of this letter appears to predominate , my opinion of the magazine is just the reverse - it is well worth reading. Bill Smith, Glen Iris, Vic. Comment: You are quite right. Much of the technology of computers is laden down with mumbo-jumbo . However, computers are in every field of electronics and it would not be right for SILICON CHIP to en tirely ignore them. Rest assured though that SILICON CHIP will stay a predominantly electronics magazine. More on microprocessor development kits Having read E. Wormald 's letter in the May 1992 issue SILICON CHIP, I am in complete agreement on the predicted popularity of a microprocessor development kit. However, I must 4 SILICON CHIP disagree on the "choosing the chipset for such a kit". E. Wormald raises the issue of board real estate being "eaten up" by various options such as RS-232 and parallel I/O, not to mention both RAM and ROM. An option that seems to have been overlooked is to use a microcontroller chip, such as the Intel 8051, rather than a separate CPU chip and various support and peripheral devices. The 8051 contains memory (both RAM and ROM), an RS-232 serial port, two 16-bit programmable timers, and four parallel I/O ports within a single 40-pin IC capable of running at a respectable 12MHz. At an average price of around $8 - the price of a Z80 parallel I/O controller alone - it is also inexpensive. This easily allows for a highly functional processor based kit to be developed with a low chip count and a simple (and therefore, thankfully, inexpensive) PC board to be used. The 8051 series microcontrollers are also available complete with a basic interpreter in ROM. With this avenue chosen, E. Wormald's problem of choosing an appropriate chip set is now reduced to a matter of choosing an appropriate chip from an entire family oflntel 8051/31 microcontrollers. A number of successful projects based around these microcontrollers have been produced by foreign magazines such as Elektorwith a high level of popularity. I am certain that this sort ofreaction could be guaranteed if a similar project was developed locally through your magazine. S. Finneran, Chipping Norton, NSW. Components hard to get I am writing to you about a serious problem that I have just come face to face with and no doubt I am certainly not alone. It concerns the publication of projects and the availability of parts. In your April edition of SILICON CHIP, you published a project for a "Differential Input Buffer for Oscilloscopes". Being in the possession (for SILICON CHIP, PO Box 139, Collaroy Beach 2097. a number of years) of a Dick Smith scope, I have on occasions not been able to check a waveform in mains equipment or in audio or electronic circuits which are not grounded. The above project is certainly an answer to a long felt need. I realised immediately that there were one or two specialised components needed and searched the magazine to see who had presented the design. Often, one of the electronic suppliers will bring out a kit. I inquired of Dick Smith and Jaycar among others to see if a kit would be available, but as yet no luck. I could see that the 11300 ICs and the VR3 7 were going to be the big stumbling blocks, so I rang around for the former. After some inquires, I managed to locate the two IL300s in a small dealer in Melbourne. Next to the VR37s: sure they could be substituted by a string of smaller resistors but that's rather messy. So far, I have not managed to get them but I think I have finally tracked down a pair of substitute resistors. It's a shame but it would seem from the above saga that it is pointless to publish projects using special components as all the electronic shops are like the supermarkets - they have their range - full stop. There doesn't seem to be anyone these days who you can go to who will order a special part for you. I know, I asked. Harry Jenner, Attwood, Vic. Comment: This sort of problem arises from time to time, especially if the kit suppliers decide to give a project the miss. However, if magazines avoided using the odd special part, many of the designs published would be either too expensive or simply impractical. You can obtain the Siemens IL300 !Cs from Reserve Electronics Pty Ltd phone (02) 906 8486. Philips VR37 resistors can be obtained from Farnell Electronic Components but you will need an account or a credit card (minimum order $5)- phone (02) 645 8888 and quote the partnumberVR371M2. SUSIE McCIADY AND HER STAR 1824·250. SUPER FASI SUPER EFFICIENI AIAl STUNNEl AND Sll's IHE PRINTEl Without doubt, the best thing to happen to the Alpasso Trading Company in the last 60 years is Susie Mccready. And the Star XB24.250 Dot Matrix printer. Nothing's too hard for this pair. Invoicing spreadsheets. Shipping manifests. And all the office paperwork imaginable, the XB24.250 is industrial strength, perfect for heavy duty applications where fast printout, superb, high resolution text and graphics are required. And there's literally a factory of fonts to choose from. The Star XB24.250. Now both business (and Susie) are looking good. SURPRISE, SURPRISE. IT'S A STAR. For more information on the Star family of business Dot Matrix Printers, contact Rolec Distributors Australia Pty Ltd, 20 Hilly Street, Mortlake, NSW 2137. Telephone (02) 743 3 144. Fax (02) 736 3732. JULY 1992 5 VINTAGE RADIO By JOHN HILL Unusual problems lead to interesting repairs The more time one spends repairing old radios, the more unusual some of the problems become. This month, we will take a look at a couple of odd repairs that took a while to work out. My first story is about an early postwar 4-valve Astor. It was a common radio in its day and is characterised by its unusual control knobs which, in my opinion, are neither attractive nor functional. The Astor was a repair for a collector friend. It was a fairly easy job really. The set was still working and only needed a few replacement capacitors, a length of dial cord and a tune-up. However, the rot started when the time came to align the receiver. The alignment procedure was car- ried out with the chassis propped up on one end and seemed to be a straightforward job. But when the set was placed right way up on the bench, the volume slowly diminished over aperiod of about five seconds to quite a low level and stayed there. Tipping the chassis upside down on the workbench to check underneath revealed nothing other than the fact that the set was now working normally again. Restoring the set to the upright position then produced exactly the same effect as before, with the volume again dropping to the previous low level. Rather than tell the owner to operate the set upside down, I thought I had better investigate further. The procedure was repeated but this time the volume remained steady. Reaching for my trusty <longer (a pencil with two rubber grommets attached to one end), I proceeded to tap various components and a single dong on one of the IF transformers reduced the volume almost instantly. It appeared as though there was something wrong with that particular component. Removing the transformer from the chassis not only revealed the problem but showed that it would also be easy to repair. One of the iron slugs that adjust the transformer had detached itself from the brass screw that controls its position. Instead of being firmly attached, it was adrift and was sliding (slowly because of a smear of grease) around inside the former carrying the transformer windings. The repair was simple - attach the slug back onto the brass adjustment screw with a drop of"superglue", then reassemble and reinstall the transformer in the receiver. After retuning the IF transformers, the set behaved quite normally. It is always satisfying to solve these odd problems because they seem so obscure at the time. The old Radiola This post war Astor of about 1949 vintage had a most unusual problem variable volume, depending on the orientation of the set. 6 SILICON CHIP Another unusual problem was encountered with an old mid-1930s Radiola which was acquired in pieces and incomplete. Missing were the knobs and the dial escutcheon - exactly the same escutcheon that I had The variable volume characteristic in the old Astor was caused by a detached tuning slug. The problem was solved by gluing the iron slug back onto its adjustment screw. previously sought for a similar model Radiola (see Vintage Radio, January 1990). Fortunately, I knew where there was a battery version of this model and it was bought solely for its knobs and escutcheon. The real problems with this set were in the receiver itself. It had been tinkered with and it was a bit different from the one I had worked on previously. The two obvious problems were an open circuit radio frequency (RF) coil and the wiring to the local station switch had been removed. The RF coil was replaced with a similar unit-with considerable difficulty - but the set still failed to work. It was quite some time before the fault was found to be the disconnected lo- Fitting this 1MQ resistor solved an annoying automatic gain control problem in a mid 1930s Radiola. Before the resistor was added, it took 8-10 seconds for the volume to settle down each time the set was tuned to a different station. Tracing out a circuit is quite difficult with this type of tagboard construction. This close-up view shows the Radiola's local station switch. This had been disconnected from the circuit, rendering the set inoperative. The two resistors connected to the switch are in the cathode circuits of the first two valves. cal station switch. This switch connects a resistor into the cathode circuits of the first two valves and if it is not connected properly, the set does not work. It is a different system from the resistor to chassis type of local station control that can be found in the aerial circuit of some receivers. I must confess that I had to have this pointed out to me, which just goes to show that working without a circuit diagram does leave one in the dark unless one is very familiar with a particular make and model. However, although the set was now working, it still had a peculiar fault. Under certain conditions, the volume control seemed sluggish and unresponsive. Likewise with the automatic gain control; it took up to 10 seconds before it responded. I don't think the term "delayed AGC" was meant to describe the problem I was having with the old Radiola. To explain this fault a little further, if the set was tuned to a strong local station and then retuned to a weaker station, approximately 8-10 seconds would elapse before that station could be heard at normal volume. Now the circuits of some of those mid-1930s Radiolas are hard to trace because they were made with little component boards containing numerous resistors and capacitors. Besides, I had no circuit diagram so I could not tell whether the wiring was original or not. The problem appeared to be in the AGC circuit so I probed the various small capacitors with a multimeter, looking for one that showed a negative voltage. The first one to indicate a negative reading seemed to be the one I was searching for because the meter probe had two immediate effects. First, there was a small increase in volume when the probe was connected. Second, the AGC behaved normally while the probe was in place. Because the meter was acting as a resistor in this position, it was apparently bleeding off the excess charge from the. capacitor, thus allowing the AGC to respond faster and work as intended. When the meter was replaced with a lMQ resistor, everything worked just fine. So that, for the present, is how it has been left. Granted this may not satisfy the purest, who would no doubt regard it as a bodgie approach. But with no JULY 1992 7 ,.. r, l .~ . , , """ Another problem with the old Radiola was a defective RF coil. Replacing the coil was no easy job as the whole coil assembly had to be removed from the chassis - and it's riveted in. These home-made valve socket plug gauges were turned up on the author's lathe. They have been made to standard base pin sizes and are used to check valve sockets for contact tension. 'If you don't have a lathe, you can use standard size drill bits. circuit and someone's butchery to contend with, it was at least a short-term solution. If the set had been bought in original condition, the problem may n ever have occurred. But when someone else has been tinkering around, anything is possible. In theory, the most likely exp lanation would involve the AGC diode load resistor, which may have gone high in value. Alternatively, an AGC line decoupling resistor could have gone high. The resistors of those days, particularly the 1MQ values and higher, were notorious for this habit. 8 SILICO N CHIP But tracing the circuit and finding them is something which will have to wait. The 5-valve Astor Although my third story is a fairly straightforward one, it taught me a lesson that is worth passing on. It all started with an embarrassing situation. I had repaired a 5-valve Astor for a lady and when she came to pick it up , it didn't work. Waggling a couple of valves in their sockets solved the problem and the receiver burst into life. In view of what had happened, I suggested that the set be left with me for a while longer so that I could check out the new and unexpected fault. Dirty and ill-fitting base pin connections are a common source of trouble in valve radios, particularly old valve radios . The Astor was no exception. After checking each individual valve socket connection with the shank of a 3/32-inch drill , it became fairly obvious that not many of them were making good contact. Some were firm, some only just touching, and others were not touching at all. The solution seemed simple: upend the chassis and, using a pair of long-nosed pliers; gently squeeze each socket connection until it had the desired drag cin the drill shank. But although that sounds a simple enough procedure, things did n ot go exactly as planned. The socket connections had been formed from rather brittle sheet brass and some of them broke instead of squeezing in. What seemed to be a simple task originally had now developed into one that required two replacement valve sockets. In the end, all the problems were solved, the lady was very pleased with the repair and I have heard nothing but good reports ever since. That experience with the ill-fitting valve socket connections prompted me to make up a set of special gauges for the purpose of checking each and every socket connection. All future repairs will have this check as a matter of course. If one looks at valve base pin sizes from the 1920s to the end of the valve era, only four different size pins w ere used (generally speaking). This excludes the split pins of some of the early British and European valves and the Loctal types. These pin diameters are a mixture of metric and imperial sizes and are as follows: 1mm (7 & 9-pin miniatures), 3/32-inch (octal), 1/8-inch and 5/32-inch (4, 5, 6 & 7-pin pre-octal). A good selection of drills allows one to check just about any valve socket that is likely to be encountered in a domestic radio receiver. This simple check can quickly reveal possible socket problems due to poor contact tension. As I have a lathe in my workshop, I decided to make up a set of valve socket gauges instead of using drill RESURRECTION RADIO Vintage Wireless Specialists Repairs - Restoration - Sales Loose and potentially troublesome valve socket connections are easily detected with the gauges. Pushing the gauge in & out of the pins five or six times also helps to clean the socket contacts. Our skilled technicians offer QUALITY repairs and restoration. We also have a large stock of bakelite and timber radios ful ly restored and for SALE. Parts are available for the enthusiast, including over 900 valve types, high voltage capacitors, transformers, dial glasses, knobs, grille cloth etc. Circuit diagrams for most Australian makes and models. Send SAE for our catalog. WANTED : Valves, Radios, etc. Purchased for CASH Call in to our showroom at: 51 Chapel Street (PO Box 1116), Windsor, Vic 3181. Telephone: (03) 529 5639 Silicon Chip Binders There are approximately 30 valve socket connections in an average valve radio. It requires only one bad contact to cause problems. Firm pin contact is extremely important & all valve sockets should be carefully checked. shanks. As can be seen from one of the accompanying photographs, these gauges have knurled handles which are less likely to cut fingers as can be the case when using drills. Checking the valve socket connections in this manner not only determines whether or not they are functioning properly but also cleans them at the same time. The best approach is to push the gauge in and out five or six times and then use a pipe cleaner to remove any dust and other undesirable rubbish. Deposits of green cor- rosion may require a more determined effort, however. There are approximately 30 "dry" connections in an average 5-valve receiver in the valve sockets alone. Tone control switches and wave-change switches also add to the number of dry connections ...:. all of which are a potential source of trouble if not carefully checked. Therefore, anything that can be done to reduce the incidence of bad connections must contribute to more reliable valve radio restorations. SC These beautifully-made binders will protect your copies of SILICON CHIP. They are made from a distinctive 2-tone green vinyl & will look great on your bookshelf. Price: $A 11.95 plus $3 p&p each (NZ $6 p&p). Send your order to: Silicon Chip Publications PO Boi: 139 Collaroy Beach 2097 Or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. ]ULY1992 9 It's the cheapest It has ever been! The famous OKILASER 400 Laser printer at only $12991 Reliable and compact, It fits neatly Into the smallest of offices. Hlghly reliable due to Its latest LED Imaging technology. The OL400 offers excellent print quality, superior paper handling, and a variety of fonts which rlvals some of the more expensive laser printers on the market 5 year warranty on LED system head. Only $1095 Tax Ex. No moving parts (LEO SYSTEM HEAO) rtJCyc/ss its own toner/ Approx. 1.8 f/ p,1/ copy. Toner Cartidge to suit only $59.00 Double your disk storage with .... DR DOS 6.0 The moat advanced, fully DOS-compatible operating ayatem available today. It's everything you need to run your DOS, Windows, and .n etworking application a faster. Maximize hard disk performance, keep your ayatem and Data secure, and make your PC easier to use. DISKMAX: 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. MEMORYMAX: moves DR DOS buffers, drivers, TSRs and networking software outside the 640K memory area, leaving more memory for your DOS, Network and Windows applications. THIS MONTHS PRICE IS THE LOWEST YET!...... $S9 95 • THE POWERMATE "GREAT 8" with Overload Prot Ideal for the garage or home. The Powermate "Great 8" has 8 outlets for all types of appliances plus it provides extra safety. It has overload protection. If it is overloaded (operating appliances that totally exceed 2400 watts or 10 amps), The overload swtch will trip, automatically turning off all appliances plugged into the Powermate. If it does overload you simply push the reset button and power is restored. P18044 ................................................................$39.95 7:J-+--•,-----·-.-.~,-'ali-.-.-. --- -.--./UJ-~-flW!l-+-1-----l (J EXPANDED DYNAMIC RAM RANGE Speed (na) LOPTIC IVE At last a floppy drive that is truly multi-purpose. You now can load and save all the 3.45" format software you are used to and in the same drive backup at 20 Mega bytes per disc. This truly remarkable drive is a GIANT leap forward in removable technology. Features: Comes with a "Grassroota" SCSI hoat adaptor card. Has an on board BIOS, so no drivers are required. Will BOOT MS.DOS using either 20MB, or 1.44MB or 720 KB disketts DOS compatible with MS-DOS 3.3, 4.01 and 5.00 BIOS compatible with PHOENIX 286 and 386 ver 3.10 AWARD 286 and 386 ver 3.02 20MB Diskettes can be bought pre~ow-level formatted Low-level formatting can be done with LFMT pr9gram supplied or using DEBUG "G:CD80:6" The unit can BOOT the aystem as drive "A:" or "B:" In either 720K, 1.44MB or 20MB format ...........................................Drive $849.00 20 M Discs to Suit... ................ :'. ...$39.00 Each. I CORDLESS TELEPHONE ', t /; '~~ ... -. - -:::-FEATURES: .J , Full Two•way Intercom • Paging • User Selectable Security Coding , Tone/Pulse Switchable , Last Numder Redail • In-use Indicator , Automatic return to standby mode when remote phone is In charge A94200 ........................was $179,QQ price $149.00 No. of pine 1·9 (64K X 1) $4.95 80 (4 X 64K) $6.95 80 (256K X 1) $3.95 70 (256K X 4) $9.95 100 (1Mx1) $10.95 80 (1Mx 1) $12.95 Speed (na) 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 (na) SIPPS 1-9 10+ 256 x 9 $21.00 80 $19.00 1Mx9 80 $79.00 $75.00 4164·10 4464-08 41256-08 44256-07 1M-10 1M--08 1M x 9 10+ $4.50 $5.95 $3.50 $8.95 $9.95 $10.95 100 70 $79.00 $75.00 100+ $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: MEss.oEL10Hr •"BEEPLESS" Remote Control Mess•oEcouNreR • Call Screening M1cRo,HoNE 7 • One-Touch Message Playback RINGER • Personal Memo Record • Voice•Activated Recording • 10 Number Speed Dailing • Power-Fail Security • Digital Message Counter • Fast Forward Rewind ~ • Built-in Microphone 1:(-:J , P (PAUSE).J • Ring Selector ,uro.J A94150 ............... was $2Q9.00 price only LND J r sro , - OIALPAO L 01.,c,o•v $149.00 MESSAGES 1-9 boxes 10+ S OF TEN DISKS LIFE 1-9+ 10+ 50+ 5 1/4" 51 /4" 31 /2" 3 1/2" TY 500+ 100+ DS/DD $4.50 $4.40 $4.30 $3.25 $3.50 DS/HD $8.50 $8.25 $8.10 $7.50 $6.60 DS/DD $7.90 $7.70 $7.50 $7.00 $6.00 DS/HD $14.95 $13.75 $13.50 $12.00 $10.00 31 /2"DD $19.95 3 1/2"HD $45.95 51 /4"DD $14.95 5 1/4"HD $23.95 3 1/2"DD $23.95 $22.95 31/2"HD $44.50 $42.50 5 1/4"DD $17.95 $16.95 51 /4"HD $24.95 $22.95 NEW CATALOGUE OUT NOW! HARD DRIVE SPECIALS Prices are without paddle cards 286-16/21....... n •....$129.00 386SX-16........................ ...... $230.00 386SX-25/31 ........................... $295.00 386-25 .................................... $495.00 386-33 64K CACHE ............... $545.00 386-33 WITH 128K CACHE.. $595 .00 486SX-20 ............................... $795.00 486-33 256K CACHE ........... $1195.00 52M QUANTAM DRIVE ............. $495.00 85M HD 17ms ACCESS VOICE COIL 2 YEAR WARRANTY................ $495.00 105M HD 19ms ACCESS ......... $595.00 126M HD 16ms ACCESS VOICE COIL 2 YEAR WARRANTY•••............. $695.00 180M HD 2 YEAR WARRANTY.$995.00 200M HD 12ms ACCESS VOICE COIL 2 YEAR WARRANTY............. $1095.00 GAMES CARD .. .. .. .....................$29 AT S/P/G 2 S/P/G ............. .......... $49 · 4 WAY CONTROLLER (360-1.44M) ... .............................$129 2 WAY FDD CONTROLLER (360-1 .44M) .......... .. .................... .$89 CLOCK CARD ............... .. .. .........$39 SMART DRIVE ADAPTOR IDE/FDC.. ........... ........... .. .. ...... .. .. $49 SMART DRIVE ADAPTOR IDE 110 FDC ............ ....................$89 512K/576K RAM CARD .. ...........$99 VGA CARD 16 BIT 250K ............$89 VGA CARD 16 BIT 512K ............$129 VGA CARD 16 BIT (1 MEG) ........$199 XT HD CO NTROLLER ......................$129 AT HD CONTROLLER ...................... $149 RS232/SERI AL CLOCK ...................$49 MONO COLOUR CARD ................... $76 MULTI 1/0 CARD .................... .. ........ $99 PRINTER CARD ................. .. .. ...... .. .. $29 EGA CARD .................. .....................$179 DIAGNOSTIC CARD ............. ...........$795 L PRINTER ...................................$89 6M AT EX/EXP.............. ......... ... :........ $325 FAX CARD ................ ........................$595 PORT SERIAL CARD .....................$199 2 WAY FDD CONT (360) ............... ....$39 RS/232 SERIA L CA RD .....................$39 1-9 boxes 10+ 1-9 boxes $18.95 $42.95 $12.95 $22.95 31/2"DD $21.95 $19.95 3 1/2"HD $39.95 $37.95 51/4"OD $11.95 $10.95 51/4"HD $18.95 $16.95 SUPA VGA COLOUR MONITOR 3 YEAR WARRANTV Y~ ~ ~ This stylish & reliable monitor has been designed for Australian conditions and comes with a 3 year warranty. Spees: CTR: 14" 90° delection, Display Size: 245+/Smm x 180+/-Smm x 180+/-Smm Resolution: (max): 1024 x 768 Dot Pitch: 0.28" ...... $469 .00 NEW SUPA QUICKSHOT JOYSTICKS e AVIATORSW Authentic Aircraft , control yoke , Automatic cantering · , 4 positive reponse buttons , 6 Foot cable with 15 Pin c onnector. • Suction Cups . •• - C14250 .......................$89.95 INTRUDER 5 , Omnidirectional Grip • Compatible with IBM PC, XT, AT and ·386. Automatic Cantering • 2 Positive Response Fire Buttons • Pop-up .Fire Button Cover , 6 Foot cable C14240 .........................$79.95 386 & 486 systems need an additional games card ... $49.00 LQ•860 80 Col, 24Pin Dot Matrix' 295 Cps Dratt.98 CPS LO, Colour U(-400 80 Col. 9 Pin Dot Matri x, 180 Cp s Draft 30 Cps NLO, Pull Tr ac tor Standard,PuM Tractor Smart Park C22054 ................... $249 Feature................... ............... $1095 LX-850 80 Co l, 9 Pin Dot Matr ix, 240 Cp s Dr aft 48 Cps NLO, Push Trac t or, Smart Park Feature C22074 .......... ........ $365 LQ- 1070136 Col, 24 Pin Dot l_!; LQ-400 80 Col, 24 Pin Dot Ma tr ix, 264 Cp s Craft 54 Cps NLO Pu s h Trac t or Smar t Park Fea ture ...................... $750 C22070..................... $439 LQ•5 70 80 Col, 24 Pin Dot ........................... ............ $775 Matrix, 252 Cps Dra ft, 84 Cp•. NLO Scalable Fonts LQ• 1170 136 Col, 24 Pin Dot 8 to 32 points , it LO Fonte 360 x 360 DPI, Top, Rear, Matri x, 350 Cps Draft, 110 Cps NLO, Scalable Fonts, 8 to 32 point, 11 LO Fonts, 360 x 360 OPI, Top, Rear, Bottom, and Front Paper Feedpaths, Converta~e Push/Pull Tractor B ottom and Fro nt paper feed paths, Con vertab le Push/ Pull Tractor. FX· 1050 136 Col, 9 Pin Dot Matrix, 264 Cps Draft, 54 Cps NLO, Pu sh Tr acto r, Sm art Park Featu re. .................................. $575 .. ...................................... $1,149 LQ-870 80 Cot, 24 Pin Dot ........................ ............ $ 9 25 Matrix,330 Cps Draft, 110 Cps NL O, Scalable Fonts, 8 to 32 points, 11 LO Fonts, 360 x 360 OPI, Top, Rear, Bottom, & Fro nt peper Feed path s Convertable Push/Pull SQ -850 80 Col , 24 Nozzel ■ii■■ .. .................................. $1,225 ~ - - - - - - - - - Tractor. --.::;: ......................................$895 LO 100 80 Col, 24 Pin Dot Matrix 200 Cps Draft, 72 LO, Fricti on paper ~e;:o:o'.~~'.~.~.'..'.~~-~~·. Matrix, 252 Cps Orefl, 84 Cps NLO, Scalab le Fonts, 8 to 32 poi nt. 11 LQ Fonts, 360 x 360 DPI, Top, Rear, Bottom, and Front Paper Feedpaths, ConvertatHe Push/Pull Tractor Matrix, 180 Cps Draft, 60 NLO Pull Tractor ~ FX·850 80 Co l, 9 Pin Dot ink jet, 600 Cp s Dra ft, 19'EI Cps LO, Pu sh Tr acto r, Sm ar t Pa rk Featu re. dark tint, non glare. ~~~~; ~pacl . I ROD IRVING ELECTRONICS Pty. Ltd. . • ACN.005428437 HEAD OFFICE: 56 RENVER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648 CIT Y 48 A'BECKETT ST. MELBOURNE. PH. 663 6151 / 6391640. FAX: 6391641, OAKLEIGH: 240C HUNTINGDALE RD, OAKLEIGH. PH: 562 8939 NORTHCOTE425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX : 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 519 3868 BLU ESTAR COMPUTERS : 271 MAROONDAH HWY. RINGWOOD . PH : (03) 8701800 . LQ• 1060 136 Col, 24Pin Dot Matrix' 292 Cps Draft. 98 Cps LO, Colour Standard,Push Tractor, Smart Park ~eature. ............................................ $1,395 LQ-2550 136 Col, 24Pin Dot Matrix' 400 Cps Draft, 133 LO Colour Standard,Push Tractor, Smart Park Feature . ..... ....................................$2,049 Postage rates $1 • $9.99-.... $3.00 The• poolago $1 0 - $24.99 .. $3.50 rate•.,.. bHIC $25 - $49.99 .. $4.50 poolago only up to 0 ;:e':lgH $50 • $99.99.. $6.00 :~lt y : $100 • $199... $7,00 llonw wtn . . $200 • $500... FREE chwgod ot dl-.1 $500 PLUS .. FREE rate• TOLL FREE MAIL ORDER HOTLINE : 008 33 5757 r------------- --, LQQK I · 1 I I ROD IRVING ELECTRONICS HAVE THERE NEW 116 PAGE 1992 MAIL ORDER CATALOGUE OUT NOW!! PICK UP YOUR FREE COPY AT ANY OF OUR STORES. 1 on your monitor I I actly where you want xlmiae deak apace! 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F1111y~1111,-,.,,, ""1>1>1; Upg,,,d. 411,.~ O eaw; 6/eo a11 1 11 ·• , •• f RITRQN F111Jy7''11Jir,eAus au/JJJJi Pgraaabt tra/iar, ·:• . oo;~Withev:DRDos ::•• EXECUTIVE RITRON ;.c-11~;, 0.:,,11.·SI "'°.01, u.og, ,,,., 4 EXECUTIVE Do::<¥,.,;"rt..(/"1,,..,,. 4i1~~1J~,~1t ···~~;J~·' t.!: :!:~t~~c•~ »-it::.•: ! :~~:;.~~~~~~.; :;~;:~;:~c;.~a.~-:i~· 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 0.28" D.P SERIAL PARALLEL GAMES PORTS 3 YEAR PARTS & LABOUR WARRANTY IBM" COMPATIBLESPREADSHEET, WORDPROCESSOR & DATABASESOFTWARE INCLUDED. •SHAREWARESOFTWARE ASSEMBLED & TESTED IN AUSTRAUA. $1 549 ' TAX INC. $1,299 TAX EX RITRON 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, WORD PROCESSOR & DATABASE SOFTWARE INCLUDED. 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IBM• COMPATIBLE SUPA VGA COLOUR MONITOR (1024 x 768 Res) 0.28" DP TOWER CASE & 'J20W POWER SUPPLY 3 YEAR PARTS & LABOUR WARRANTY SPEADSHEET, WORDPRCESSOR & DATABASE SOFTWARE. ASSEMBLED.& TESTED IN AUSTRALIA. IDEAL CAD MACHINE! TAX INC. $3 9 '2 5 $2,795 TAXEX. TAX EX FREIGHT CHARGE BASED ON 35KG COMPUTER SYSTEM MAIL ORDER HOTLINE: 008 33 57 57. ORDER FAX LINE: (03) 543 4871 ENQUIRES (03) 543 7877 HEAD OFACE: 56 RENYER RD, CLAYTON. PH: (03) 543 2166. FAX (03) 543 2648 CITY 48 A'BECKETT ST. MELBOURNE. PH. (03) 639 1640. FAX: 639 1641. OAKLEIGH: 240C HUNTINGDALE RD, OAKLEIGH. PH: (03) 562 8939 FAX: (03) 562 8~ NORTHCOTE 425 HIGH ST. NORTHCOTE, PH. 489 8866. FAX: 489 8131. SYDNEY:74 PARRAMATTA RD, STANMORE. PH: (02) 519 3134. FAX: (02) 516 5024 BLUESTAR COMPUTERS: MELBOURNE: 271 MAROONDAH HWY, RINGWOOD, PHONE: (03) 870 1800 FAX: (03) 879 3027 SYDNEY: 115 -117 PARRAMATTA RD CONCORD. PH: (02) 744 5526 FAX: (02) 744 5405 Melb-Metro.$12.00 Sydney...•... $17.00 Adelaide ..... $17.00 Bribane ••••• $24.00 Canberra .... $18.00 Vic country, ••. $19.00 NSW country.$39.00 S.A country.• $39.00 OLD country.$55.00 W.A country•.$74.00 Darwin. ....... $40.00 lnsurance:Perth ..•••••••••$31 .00 $1 / $100 Value. Taam1ni1 .... $53.00 All sales tax exempt orders to : RITRONICS WHOLESALE 56 Renver Rd, Clayton, Victoria. Ph: (03) 543 2166 Fax . (03) 543 2646 MAIL ORDER & CORRESPONDENCE P.O BOX 620, CLAYTON, VICTOR IA. 3168. Error ■ & omml ■ .m ■ excepted. PricN & ■peclfl caUon ■ -.,bjecl lo change. •1BM, PC, X1; AT, are reglatered tr1domartt ■ of lntematlonal Bu ■ lneH Machlnea. PRICES AT AUS S ■ US $0.74 FECTS MIXER A consol or freestanding mixer wilh B inbuilt special effects. Designed for both OJ and studio use. The following inputs are provided: 2 x tumtablea • 4 x line inputs• 2 x low impendance microphones. Eight special effects: alren, telephone, machine gun, bombing, shooting, ambulance, thunder, laser. Other features: bas• & treble control, Headphone Cue monitoring, CH1 to CH2 cross fader, mic talkover switch, master volume level control and left & right LED VU meters. INDOOR SPIRAL ANTENNA • 300 ohm ribbon cable antenna • Suits AM/FM tuners and portable TVa. • 1 Meter lead with 300 ohm spade terminals L 15040......... $9.95 A12013 ..................... ................. .......$299.00 VIDEOCAM / VCR , . AUDIO MIXER '· .. ·. A professional audio mixer · designed for the serious home video movie maker through to the home video camera user. Background music and effecta can be faded in and out to existing video tape sound tracks. Ideal for weddings, fami ly, sporting and other recording a. , Input for s video camera, VCR, CD, tape, tuner, auxiliary and turnta~e. • Mic panpots • Mic faders • Turntable faders• VU meters• Mono/stereo awitches • CO/Tape fader & more. A 12004 .............................. ... ..... .......$169.00 FOUR CHANNEL STEREO AUDIO MIXER • Compact portable desk mount or panel mounting stereo mixer with 5 band equalizer and twin LED display UV meters. • 3 x stereo magnetic tunable inputs switchable • Headphone monitoring on all channels • 18 dB talk over switch • Output sockets for both the amplifier and tape deck. A12012....$399.95 AUDIONIDEO ONE INRFA RED REMOTE CONTROL FOR YOUR VCR, TV, CD, HIFI & Aux! This unit will replace all your existing remotea & la programmable to replace future ones. Has liquid' crystal display, clock, alarm, and countdown COMPUTER ACCESSORIES MOUSE CLEANING KIT 31/2" HARD DRIVE MOUNTING KIT 2 Universal brackets with screws to mount 3 112" hard drives into computer than 10 nanoseconds. Automatic resel X10060 ....... $25.00 ~- ,r,~~ \-::;3_., .~--:-l Plugs directly into your equipment and replaces your existing cord-set. Clear moulded plugs at both ends with green safety neons that glow when power is on. Approval Numbers: V88029, V900297, V85006 Total energy rating: 225 Joulea (10/lOOOus) Protection level: 275V Nominal, 475V Peak Response nme: Better than 10 nanoseconds. Automatic reset. X10080 ....... $39_.95 VHS VIDEO HEAD CLEANERS New "wet, dry, wet" system cleans and dries all parts which come into contact with the magnetic tape. Fluid ia applied directty on to cloth cleaning tape prior to use. It uses clean tape for each cleaning operation. low drag for use la sensitive mechanism a M23523 ......$22.95 A11456 ....... $16.95 DUST COVER - A 14005.......$4.95 POPULAR DELUXE HEADPHONES These headphone• have large aoft ear cushions aa well as having Individual left & right channel control A 14005......$34.95 VIDEO/AUDIO TRANSMITTER A small compact unit that allows transmission of video & audio aignals (RF) to any TV or set VCR within range of 30 meters. Ideal for watching video• in the bedroom or kitchen without having to move the entire VCR or having long extension leada running through the house. Can alao be used H a transmitter for• · video camera. With power on/off switch audio and video leads and supplied with an AC adapter. A1s1so. was $95.95 now only $84.95 I MOUSE KIT Everything you need to keep your mouse happy I You get a mouse pad, a mouse holder, a cleaning kit (previously described) and a cute little mouse cover. C21072 .....•.......•. $16.95 XT' Cover Set AT' Cover Set C21068 .........$16.95 MOUSE GIFT SET Here it isl The ultimate mouse kit. You get the cute little mouse cover to protect it from dust, the mouse cleaning kit with the rounded tool & 5 cloths, the mouse house and mouse pad all in • handy black case. C21074 ............... $19.95 C12561L •.•.••••. $6.95 •51/4" C12555............$4.95 C10233 .......... $44. 95 • - 10" HIGH POWER WOOFER • With ribbed block paper cone. • 40 watta • Black dust cap • Clolh edge • Rubber mounting seal C10228 ....... ... $49. 95 1 0" DOPED PAPER CONE • High compliance rubber aurround. • 60 watta RMS • Dark grey cone • Black dust cap • Black round frame C10238 ..........$59.95 G) 8" FULLRANGE • Twin cone speaker with white paper cone ideal for public addreso column speaker&. • 30 watts RMS • Foam edge • Whizzer cone • 12" HIGH POWER WOOFER • With ribbed black paper cone • 50 watta • Black dust cap • Cloth edge • Rubber mounting eeal C102291P4.95 HEAD CLEANER DISKS It takes only • minute amount of dust, dirt, or magnetic oxide particlaa on your drive heads to cause problems, errors downtime or expensive service call. Regular use of a head cleaner will keep your drive free of trouble causing dirt and help keep your aystem up and n.mning. These disk cleaners are simple to uae and include deaning aolution and inatrucilona. • 3112" - 8 " DOPED PAPER CONE • High compli ance rubber surround. • 45 watta RMS • Dark grey cone • Black dust cap , Black round frame C10224 .......... $24.95 C21066..............$14.95 . Impedance: 32 ohm• Sensitivity: 96dB Freq. Response: 4010000Hz Cord length:1.2m C21071 ................. $9.95 use. . MINI STEREO EARPHONES Keep dual and dirt from damaging your mouse with this handy mouse cleaning kil This special rounded tool will find ita way into all the hard to get at places. The kit alao comes with deaning fluid and 5 aoft cloths to keep your mouse spottessl Keep your computer and acceuoriea free of dual and grime while not in HEADPHONES ~ SURGE/SPIKE SAFETY CORD Set 3 pin Mains plug to 3 pin IEC plug r Nickel cadmium battery charger for charging up to aix batteries simultaneously. Charges UM3, UM4, & UMS nicada. Charging circuit• are automatlcally selected depending on ·the physical size of the battery and the charger. Charging time 10· 14 houra 240V AC mains operated. Requires NM4 or NM5 charging modules if UM4 or UM5 batteries are to be charged. $795 Ul) X19971 ........ $9.95 Plugs into socket adjacent to the equipment that you want to protect. All outlets on a power board can be protected by Inserting the Triangle Surge/Spike Plug into any of the free outlets. Green safety neon glows when power is on. Approval No. VB8029 Total Energy rating: 225 Joules (10/lOOOus) Protection level: 275V Nominal, 475V Peak Response nme: Better C2100l] timer ••.•••.•......•••• $67.95 cases. NBC-2 BATTERY CHARGER MOUSE COVER Be the first In your office to have • mouae that every one win want uae. This cute little mouse cover puts a bit of fun and colour onto your desk while keeping your mouse free of duatl 6" HORN & LINE X'FORMER COMPUTER CLEANING KIT To gain optimum performance and prevent damage to valuable diska, this cleaning kit has all you need to keep your computer In top notch performanoe. Anti.static cleaning pada, cleaning awabe, cleaning solution, 5 1/4" & 3 1/2'' cleaning • diakettea. C21077 •..••.......•.•$19.95 • Weatherproof plaelic horn with 100 volt line transformer • 15 watts RMS • Adjustable metal bracket C10218 ...........$74 .95 New 1992 Mailorder INVEST IN OUR FUTURE'S POWER SOURCE Do you hava an appllcatlon for FREE anargy? Does your alactrlclty bill glva you nightmares? Can you afford tha Insurance premiums when all your night tlma visitors you altar tripping on dark paths? Has your head stopped aching altar running into that door In the middle of the night? Wall hare's your answer:- Convert that fraa solar power into alactricityl The SIiicon Solar Call technology was pionaarad for space power appllcatlons and now has becoma widely adapted to find everyday llama. •\I• 12V. Voc 16V (max) 18V lsc 400mA (max) SOOmA 9028 ..............$99.00 12V 16V (max) 18V ;!, lsc 1200mA (max) 1500mA Z19038 ................$299.00 12V Voc•16V (max) 18V lsc BOOmA (max) 1000mA Z19036 ................$199.00 z, SOLAR POWER CHARGERS ~:~1t1 ~ "!:-,,~~~;J(O:fi ""~1-~ m ENCAPSULATED SOLAR CELL MODULE 0.45V 200mA These are Ideal for simple solar experimemta. Can be connected with other solar cells. 219001 .........................$2.95 SOLAR EDUCATIONAL TOYS SOLAR WOODEN MODELS Build great little solar powered wooden models with thia kill There are 3 different models to choose from a helicopter with working motor, aeroplane with working motor and gramophone that plays music. Each kit contains a set of precut plywood, PVA cement, assembly instruction sheet, solar cell module, musical IC or small DC motor, wire and ■ and paper. 219044 Aeroplane ........... $19.95 219046 Gramophone...... $19.95 219048 Helicopter........... $19.95 SOLAR CAR BATTERY CHARGER Never worry about your car battery going flat when left without being used over a prolonged period of time. Simply place the 1olar power unit on your dash or near a window In your garsge and plug it into your car cigarette lighter. The unit consist• of aolar cells in a housing with 1 metre of cable and cigarette lighter plug. 219054 ..................., ..........$29.95 t~ This la a great starter kit conalatlng of 1 0.9V 400mA aolar cell and a small motor with a 48'" wire. Great for beginner or juat the curious! Z19040 ..........., ............ $9.95 Ff~ SOLAR BICYCLE WARNING LIGHT AND BATTERY CHARGER. for 2 'AA' size batteries 2190,56 ..............................$19.95 Leam what solar power la and how to build your own solar ayatem. With thia great kit you can make an electrical circuit. l.eam how to lncreHe voltage, learn how to Increase current, tearn r.l'...-,t'm''".JI how to make a solar panel, uae solar power to produce the energy for a radio, calculator battery charger or 1.5V caasette player Z19042 ....................$22.95 SOLAR MUSICAL KEYCHAIN WITH LIGHT. Never lose your keya again with this clever little device. The solar powered keychaln with light will let you find where you left your keys where you left them just by listening to music. The 1olar powered light will always let you find that illusive keyhole in the dark. A very handy idea and all run on FREE power! 219060 .. .... .......................... $4 .95 219062 ..................................$4.95 DYNAMO & SOLAR A /FM RADIO WITH 4 WAYS POWER BACKUP SOLAR POWERED LIGHTS SOLAR MOTOR KIT KEYCHAIN BATTERY ANALYZER FOR TESTING ALL SIZES .OF BATTERIES SOLAR BATTERY CHARGER FOR 'AA' SIZE BATTERIES Thi■ 11 the radio that every trawller ahould have I You will never run out of energy aourcea for this little radio because It has for different power sources:• Solar, Manual Winding, DC Charging, '"AA"" batteriea. 219064 ............................. ...$39.95 Z19050 ............................. $12.95 RECHARGABLE SOLAR LI HT • Automatically turns on & off at night and day • Detachable solar panel for indoor or outdoor use • unique protection for low voltage discharge circuitry makes charging easy and quicker! • Easy to install, equipped with accessories for easy assembly beside the house number, pathway, side of the house, in the garden, sitting room or study room .... etc. 219060............................. .$39.95 EOYQHARGI .6.houni of charg va 12 hciura of u ... nightf ) Understanding the world of CB radio Have you wondered about becoming involved with CB radio? Perhaps you are thinking about buying a CB radio for that next country trip. If so, this article for you. It gives the background and history of CB radio and talks about the 2 71\.1Hz and UHF bands. By HERB ZALLNER CB Radio as we know it today had its origins in the late 1950s, in the USA. On 11th September, 1958, the FCC inaugurated a "Class D" service, allocating 23 channels between 26.965MHz and 27.255MHz. The service was designed to be used for specific purposes, none of which related to hobbyist use. Interest in the new service soon grew and within 12 months, over 40,000 operators had been licensed. This service ran until 1971 when it was dissolved and users were allocated other more specific services. In 1973, the USA was in the grip of an oil crisis. Fuel supplies were scarce and a 55mph speed limit was brought to bear. For "truckers", who had al16 SILICON CHIP ready been subjected to a price and wage freeze at a time of rocketing costs, the speed limit was the last straw and they went on strike. Millions of Americans saw news bulletins showing truck drivers with 2way radios organising their blockades of tollways and interstate highways. Motorists bought CB sets to hear the truckers telling one another, after· the strike was over, where scarce pet_rol was available and where highway patrol cars could be found. Citizen's Band radio had been born. By 1976, the FCC found it impossible to police the number of licensees and "pirates" occupying the CB service and decided to lift most restrictions, including one which had previ- ously prevented hobby use of the band. The result was incredible. Within the next eight months, one million licenses were granted and another million were granted within the next three months. The US CB band contained 23 channels in the 2 7MHz band and allowed 4 watts of AM power. The transceivers used a method of frequency generation called crystal synthesis or "crystal plexing", which utilised 12 or 14 crystals and three oscillators to cleverly create both transmit and receive frequencies. This was a great saving in cost over the previous crystal controlled sets , which had used 46 crystals. At last, affordable transceivers were Above: the Uniden Pro 810e is an AM/ SSB base station for the 27MHz CB band. Its features include separate volume, squelch, RF gain & clarifier controls, a noise blanker switch, a 7W audio amplifier, a PA facility plus external speaker provision, and an illuminated signal/RF meter. (Dick Smith Electronics). Table 1: 27MHz CB Channels 18-CH Set 1 2 3 4 5 Designed for in-car use, the Uniden PRO 640e is a top-of-the-line AM/SSB-CB radio. Among its many features are digital readout of channel number; a LED bargraph for signal strength, RF output & SWR; & direct access to emergency channel 9. It covers all 40 channels in the 27MHz band on AM, LSB & USB. (Dick Smith Electronics). available to the general public and by 1977 several organisations had made submissions to the Australian government fo r the intro duction of an official CB band. In the meantime, this did not prevent the sale an d consequential illegal use of tens of thousands of CB transceivers using the US 23-channel system while the various submissions w ere under review. A further complication arose in 1976 when the USA service was expanded to 40 channels to cater for increased demand. Finally, the Australian governm ent decided to implement a compromise 18-channel system proposed by Dick Smith as the best alternative for local conditions. This channel system was designed to allow the maximum number of channels without causing interference to existing services. Table 1 shows the 18 and 40-channel frequency allocations. After several years of successful operation of the 18 channel system , Australia followed the USA and implemented the same 40 channels in the 27MHz band. SSB operation by this time was allowed and despite the regulatory restriction of" communications only within Australia", the tantalis- ing possibility of communicating with another country added more appeal to users of the service. CB became an outlet for social communications, allowing users to communicate with others at no cost (other than the initial licensing fees) and without th e burden of the technical examination required of amateur operators. After all, most enthusiasts claimed that the radio spectrum was a national resource and that they should not be denied the right to use it for social means. The service also provided low-cost communications for business people, even considering the lack of privacy and unpredictable communications range, a result of operating on the 27MHz band. In 1977, Philips Industries proposed a "personal radio" band utilising part of the UHF spectrum and using FM as the transmission mode in the 476477MHz range. It was envisaged that this would eventually replace the 2 7MHz band service and, in the meantime, ease congestion of the 27MHz band. It would also allow business users the same communications facilities as the 2 7MHz service while allowing some reuse of frequencies, as a result of the 10-25km "line of 6 7 8 9 10 11 12 13 14 15 16 17 18 40-CH Set Frequency 1 2 3 4 5 6 7 8 9 10 11 26.965 26.975 26.985 27.005 27.015 27.025 27.035 27.055 27.065 27.075 27.085 27.095 27.105 27.115 27.125 27.135 27.155 27.165 27.175 27. 185 27.195 27.205 27.215 27.225 27.255 27.235 27.245 27.265 27.275 27.285 27.295 27.305 27.315 27.325 27.335 27.345 27.355 27.365 27.375 27.385 27.395 27.405 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 sight" coverage achievable with a UHF transceiver. In the same year, Philips introduced their "FM320" 40-channel UHF personal (CB) radio transceiver which , despite its high price, was an instant success. Subsequently, in November 1979, Philips also installed the first UHF CB repeater at Lysterfield in the foothills of the Dandenong ranges. Approved under an experimental JULY 1992 17 Retailing for around the $450 mark, the Pearce-Simpson UF-2020 UHF CB has microprocessor control to provide scanning & a range of other specialised functions. The front panel can be mounted remotely, so that the main body of the rig can be located anywhere within the vehicle. license issued by the DOC, this allowed enhanced coverage beyond the normal simplex limitations of a UHF transceiver, thereby adding considerable appeal to the UHF service. Thereafter followed an enormous influx of imported UHF transceivers and the formation of various CB clubs, which subsequently installed UHF repeaters all over Australia. In many cases, UHF CB became a viable alternative to commercial 2-way radio, although this was not the intention of licensing authorities. Table 2 lists the channel frequencies in the UHF CB band. Today, there are over 400,000 licensed CB operators in Australia, proof of the success of the service. Both the 2 7MHz and UHF bands coexist, serving hobbyists and commercial users alike. Emergency monitor- ing services exist in most country towns and outback travellers use CB radio for communications, as do farmers, truck drivers, commercial users and many country police officers! Selecting a CB set The price of a CB transceiver ranges from less than $50 for a basic AM transceiver to several hundred dollars for a sophisticated SSB or UHF "rig". Don't make a rush decision when buying equipment; your purchase deserves some consideration. If the intended application is city use only, UHF offers FM clarity and repeater enhanced operation. Small antennas can be used and there are plenty of mobile transceivers from which to choose. If the application involves outback communications, then an AM/SSB The Uniden Sundowner is typical of CB radios designed for the UHF band. It covers all 40 channels, features digital readout of channel number & features duplex switching for operation through a repeater station. (Dick Smith Electronics). 18 SILfCON CHTP transceiver, able to take advantage of the 27MHz propagation or "skip" conditions, is the best choice. After all, when calling for help, the larger the audience, the better! Also, a longer antenna can more easily be tolerated when driving in the country, as there are less obstructions to interfere with a 3-metre whip than in the city. Base stations are available in both 27MHz and UHF, although the 27MHz models are somewhat better presented and often include SWR and output power metering, in addition to an inbuilt 240V AC power supply. Having selected a suitable transceiver, a suitable antenna must be chosen. The most popular 2 7MHz mobile antenna is the helical whip. By winding a quarter wavelength of wire on a fibreglass whip, antenna makers have been able to achieve reasonable matching, radiation pattern and mechanical flexibility. Both ground dependent and independent antennas are available. If the antenna is to be mounted on a metallic car body, a ground dependent antenna is necessary. If the mounting position is such that a good groundplane cannot be achieved (critical if the antenna radiation pattern is to provide any gain), then a ground independent antenna should be used. Typical mounting locations for a ground independent antenna would be the rear bumper, mirror mounts or the bullbar of a motor vehicle. Base station users are well catered for, with high gain (9dBd) collinear antennas and directional Yagi antennas available for UHF users. 27MHz operators can utilise full length halfwave antennas and more adventurous operators have even been known to install rotatable Yagi antennas (quite an undertaking at this frequency)! Most CB antennas come equipped with coaxial cable, however the quality of the cable used for UHF installations is critically important. Coaxial cable used at UHF can be used at 27MHz but the reverse is not always true. the loss of signal through a low quality coaxial cable at 27MHz is of little consequence but at UHF it can reduce transmitter output power and receiver sensitivity by 50%. Likewise, coaxial connectors are important, as they provide impedance matching between the transceiver and the antenna. For UHF, premium qual- ity connectors must be used to minimise losses. Transceivers installed in motor vehicles require careful mounting and connection. Care must be taken to ensure that the transceiver is mounted securely, so that if an accident occurs, it remains mounted on the dashboard, where it cannot harm the occupants. Power connections should be made directly to the car battery, eliminating the possibility of vehicle accessory noise being fed to the transceiver. All CB transceivers sold these days are negative earth, allowing the chassis to be directly connected to the vehicle body. The suppression of ignition interference is of great importance to 27MHz users, who do not have the benefit of the intrinsic noise immunity afforded by FM. Ignition noise can either be radi- The "Sea Simba" is a 27MHz CB radio specifically designed for marine work. It has 10 channels, 5W output power, a loudhailer/PA, automatic noise limiting, and adjustable RF & mic. gain. (Hatadi Electronics). Designed for the serious operator, the Pearce-Simpson Super Cheetah MkIII boasts an in-built scanner, 40-channel AM/SSB operation & a noise blanker. It's sold by Jaycar Electronics. ated or conducted into a CB transceiver. The use of suppression spark plug leads, grounding the end of the vehicle exhaust system (which can act as an antenna, hung under the body of a car by rubber bands) and earthing the bonnet by bonding the hinges using copper braid, will generally eliminate radiated ignition noise. Direct connection to the vehicle battery is the best method to eliminate conducted noise. Licensing One license per transceiver is required for the operation or possession of a CB transceiver. Licenses are easily obtained from the Department of Transport and Communications by filling in the appropriate form (DOC5 7A) and payment of the appropriate fee. DOTAC will then issue a callsign and an operating guide. CB operation is permitted on a non interfering basis. This means that if interference is generated by a CB operator, DOTAC can request the operator to minimise interference by restricting operations until the technical reason for the interference can be determined and a cure implemented. In some states of Australia, it is an offence for drivers to use radio communications equipment while driving. Finally, all equipment must be type approved, in the case of 27MHz equipment to DOTAC specification ECR312 and for UHF, ECR250. As unapproved CB transceivers are prohibited imports, virtually none appear for sale on the Australian market. CB etiquette As any shortwave listener knows, CB and amateur operators have developed a "language" of their own. Table 3 shows what are called "10codes" and "Q" codes. The idea of using these codes was originally as an aid to communications in poor conditions. These days they are used more as jargon. As the CB bands can be shared by everyone, certain band plans have been devised to ensure that, for instance, SSB does not interfere with AM stations and so on. Basically, the 27MHz plan, part of which is law, states that only AM can be used from channels 1-14 and that SSB can only be used from channels 15-40. Also, certain channels have been dedicated for specific uses as follows: Table 2: UHF CB Channels Channel Frequency 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 476.425 476.450 476.475 476.500 476.525 476.550 476.575 476.600 476.625 476.650 476.675 476.700 476.725 476.750 476.775 476.800 476.825 476.850 476.875 476.900 476.925 476.950 476.975 477.000 477.025 477.050 477.075 477.100 477.125 477.150 477.175 477.200 477.225 477.250 477.275 477.300 477.325 477.350 477.375 477.400 34 35 36 37 38 39 40 Use Emergency Call channel Emergency Road channel Channel 8: AM only. This is the highway channel. It is used by truck drivers, travellers and base stations along main rqads to pass information relating to traffic conditions. Channel 9: AM only. This is used as the emergency channel and is monitored by rescue and volunteer groups around Australia, who have fast access to police, fire, ambulance and emergency services. Channel 11: AM only. This channel has been allocated "call channel" staJULY 1992 19 Table 3: The Language Of CB Radio 10.100 - rest stop; often interpreted as rest room stop! THE COMMON 10-CODF;S 10.1 - poor reception; have difficulty receiving you 10.2 - good reception; receiving you well 10.3 - this channel in use, stop transmitting 10.4 - acknowledgement; message received 10.5 - relay message 10.6 - I'm busy 10.7 - closing down (usually temporary close down) 10.8 - back on after closing down 10.9 - repeat what you just said, repeat last over 10.1 O - ready now, was busy 10.13 - please advise weather, road conditions 10.18 - anything for me? 10.20 - location (same as 0TH); often used as "hometwenty" or just "twenty" 10.21 - call by telephone 10.23 - standby (same as ORX) 10.27 - I am moving to channel. .. 10.28 - identify; what is your callsign (same as ORZ)? 10.32 - signal check; usually used to give signal reports 10.33 - emergency traffic at this station 10.34 - in trouble, need help 10.36 - correct time (you never get it!) 10.41 - go to channel ... (same as OSY to .. .) 10.44 - I have a message for ... 10.50 - break channel 10.77 - no contact, not receiving you, negative contact Looking for an economy handheld model? This unit from Dick Smith Electronics sells for around $100 & comes fitted for 1-channel operation. 20 SILICON CHIP 10.200 - police needed at... THE COMMON 'Q' CODES ORA - name or handle (what is your name; my name is ...) ORB - how far away are you? ORG - what channel am I on? ORL - busy (I am busy; are you busy... ) ORM - interference; generally from other stations ORN - natural or noise interference; static, car ignition etc ORP - low power (applies to those who have a high power/low power switch) ORT - going off the air; to stop transmitting ORU - nothing for you (or have you anything for me?) ORV - ready? - I'm ready! ORX - standby ORZ - what's your callsign? or who's calling? OSA - signal report (5 by 9, or 4 by 5 or whatever) OSB - fading or "flutter' on signal OSL - acknowledgement; same as "ten-four" and "roger". Used to affirm receipt of message or information. Hence, OSL cards OSO - contact OSP - to relay a message OSY - change channels or frequency 0TH - location (same as 10-20) OTR - correct time is ... tus and is used to establish initial contact. Once contact is established, operators are required to move to another channel to continue their conversation. Channel 16: LSB (lower sideband). This channel has been designated the "SSB call channel". Only LSB is used and once contact has been established, operators must move to another channel. Channel 35: LSB. Secondary SSB call channel, particularly for stations desiring long distance "DX" contacts. UHF operators have also dedicated specific channels for certain usage: Channel 5: UHF emergency channel. In mos.t capital cities, a repeater operates on this frequency (channel 5 receive, channel 35 transmit) to provide greater coverage of emergency services. Channel 11: UHF call channel. Channel 35: Secondary emergency channel. As well as being the input frequency for emergency repeaters, it can also be used for simplex emergency communications. Channel 40: UHF highway channel. In addition, UHF repeaters operate from channels 1-8 and 31-38 and can only be accessed using the duplex mode on UHF CB transceivers. As each channel is separated by 25kHz, this 30 channel "split", when using the repeater mode, equates to a fre quency difference of 750kHz. Good operating practice dictates that repeater users keep transmissions short. In fact, all UHF CB repeaters are fitted with a time-out function, which automatically switches the repeater transmitter off if the input signal is held up for too long. It is also good etiquette to always wait a few seconds after the audible repeater "tail" drops out before re-transmitting through a repeater. This gives other stations the opportunityto "break in", before they travel outside the range of the repeater. It is wise to check the input channel of the repeater during a conversation, just in case the other station can be heard at good signal strength. If this is the case, the stations should move to a simplex channel to leave the repeater free for others. SC LARGE LCD DISPLAY MODULE Save by making your own 12V laser inverter kit. This combination includes a He-Ne visible red laser tube and one 12V universal laser power supply kit - Mkll. This inverter features easy construction since the ~:~;~g~~r ~~:l~~'Xive all the 0.2-15mW tubes efficiently. Universal 12V supply plus a used 2-3mW tube or head s99 Brand new large Hitachi LM215XB display, as used in some laptop computers. Yellow-green LCD reflective type, 480 X 128 dot display, effective display area of 242 X 69 mm, has 14 LSI ICs mounted on the rear of the PCB. Includes four pages of data sheets. Limited stock at a small th :::.:t~a~u~ eir ea. (Item No. 0132) $39 One extra tube or head $30 extra. Only with initial MAINS OPERATED LASERS , . PASSIVE NIGHT VIEWER I Consider this mains operated laser for discos, laboratories, photography, holography, medical use, etc. We supply a brand new laboratory quality HeNe visible red laser tube, with its matching encapsulated (240V AC) power supply. (Item No. 0112) 8-10mW tube with its mains power supply $390 (Item No. 0114) Other combinations may also be available: Ring. PROJECTION LENS . . (Item No. 0105X) projection lenses, which were originally intended for big screen TV projection systems. Will project images at close proximity, onto walls and screens and it has adjustable focussing. Main body has a diameter of 117mm and is 107mm long. The whole assembly can be easily unscrewed to obtain three very large lenses: two plastic and one glass. The basis of the cheapest large magnifier or projection ON' ·y system? Experimenters delight at L (Item No. 0137) Universal Supply Kit plus a new 10mW tube $299 (Item 0107) Note that we may also have in stock some second generation tubes similar to the ones used in these viewers, but with some blemishes. These will be priced between $500 and $700. Ring. I.R. BINOCULAR VIEWER 2-4mW tube with its mains supply $240 (Item No. 0113) Brand new large precision Universal Supply Kit plus a new 5mW tube $189 (Item No. 0106) $1800 $179 purchase. Universal Supply Kit plus a new 1mW tube $129 (Item No. 0105) $28 High quality military binocular IR viewer. Self powered, and originally intended to be mounted on a helmet. Focus is adjustable from 1 metre to infinity. Requires some IR illumination . Powered by one single 1.5V battery. Original fibreglass carry Ef~rtt,;~~~tt s549 (Item No. 0125) VISIBLE LASER DIODE POINTER-PEN l In the form of a telephone display. Based on an NEC uPD7503G single chip micro computer. Apply power to the unit and the display will show date and time (Xtal controlled oscillator on board) but this is only a small part of the micro computer's features: 4 bit single chip micro computer, 4 bit parallel ALU, 8 bit serial interface, 4096 X 8 bit words of ROM, 224 X 4 bit words· of RAM, 23 general purpose 1/0 lines, 24 line segment outputs and 4 lines common outputs for driving LCDs, instruction set enables direct memory addressing, can be battery operated (3.5-6V), extremely low battery consumption: less than 1mA whilst operating, less than 10uA in standby. Connection to the phone display can be made by simply pushing wires into the socket provided. One complete 15 page set of instructions on the uPD7503G and a circuit diagram of the phone display will be provided with each order for one or more of the phone disp~~tv $15 ea. OR 5 for $60 (Item No. 0133) Small black anodised metal body. Removable pressure switch. Vertical and horizontal adjustments. Battery life more than 10 hours continuous. 5mW 670nM class IIIA laser. Range is about 150m, some would claim three times more. Shock tested to 2000g. One year warranty. ONLY $299 Price includes one rifle or pistol mount (Item No. 0108) .· These custom made viewers will produce useful images with • starlight illumination only. Can be IR assisted, in • rare situations where this ~. . . may be required: In these cases low power IR LEDs, IR lasers, or low power torches fitted with an IR filter can be employed. The viewers employ an exmilitary 18mm fibre optically coupled second generation image intensifier. They also have automatic gain control, to protect against pcssible excessive lighting levels. Limited availability at a super price (Item No. 0145) Suit teachers, doctors, businessmen, and other professionals. Improve and enhance all your presentations. Not a kit, but a complete commercial pen sized laser pointer at an incredible price! ON SPECIAL AT s1ao Small pen sized body. Runs on two small AAA battery. Battery life: 2-10 hours. Visible 5mW red (670nM) laser. Projects a visible red spot at more than 50 metres. As used for medical treatment by doctors and acupuncturists. (Item No. 0101) VISIBLE LASER DIODE HEAD Save, by making your own laser pointer, laser gun sight, medical treatment laser, etc. Produces a well collimated beam. Designed to be powered directly from a 3V battery, or from higher voltages, if a simple coristant source is added. Simple circuit included. 5mW (670nM). At an incredible introductory price of: For the head only. Add $8 for the extra "bits" needed to make a complete laser diode pointer. Case, switch, alkaline batteries, and battery holders. Everything you need to make a complete, self contained, visible laser pointer or gunsight. (Item No. 0103) s135 Can easily be re-built as a hand held binocular IR viewer. Note that the $649 units are in "as new" condition. We may have some units that need a little cleaning at lower prices. Ring . Brand New high quality US made, amorphous glass Solar Panels. Dimensions: 150 X 150 X 2.5mm. In normal sunlight they deliver a full 1 Watt whilst charging 6V-8V batteries! Can be connected in series, in parallel, or series/ parallel, to increase the voltage, and/or current capac ity. For example, in average sunlight, two of these panels connected in series will deliver approximately 150mA of charging current, into a floating 12V (14V) battery: 2 Watts! Four panels can be connected in series parallel to deliver 300mA into a floating battery: 4 Watts! Compare the prices! All the panels have a weather protection film on rear, and the terminating clips are provided. ~NR~~l~~~LE $ 10 NIGHT VIEWER BARGAINS ~~~. A very small telescopic monocular IR viewer. The assembled scope has high quality military grade optics, and employs a prefocussed IR image converter tube. This tube has a useful response from 600-1300 nM, thus also making it useful when working with IR LEDs, and IR laser systems. The scope has provision for a coaxial E.H.T. connection, and is supplied with a power supply kit, that features a ready assembled inverter on a small PCB. The power supply easily fits into a small plastic case, and can be fitted with a belt clip: Also supplied! At a very small ia $269 ::.':.~t~a7u~! its (Item No. 0121) . We can also supply the same monocular viewer with its original power supply. Powered by a single 1.5V C type battery. In this case all that is needed is connecting the scope to the power supply unit via a coaxial cable, wh ich is $ also supplied. (Item No. 0122) 289 NEW CRO TUBES AND VALVES ea. or 10 for $85 (Item No. 0130) We sold out of these tubes with in two days of publication of the Mini Night Viewer in Oct. 91 E.A., but have now located a further small quantity. These first generation tubes produce a very high resolution picture because they use fibre optic windows, will produce a useful picture with moonlight illumination, an~ can be IR assisted with IR illumination: 800-900nM. The tubes are used and may have very minor blemishes. For the tube and a high voltage inverter only. (Item No. 0124) $299 For further reading on Night Viewers see: Electronics Australia (E.A.) May 1990, E.A. Sept. 1990, E.A. Oct. 1991. Australian Photography Dec. 1991. , CRO tubes: 1" electrostatic deflection type number CV1522 $35. 3" spiral PDA electostatic dellection type numbers DP-10-6 and 4VP7 $44. Mercury vapour rectifier valve type 866A/866 $5. Pentode valve type 6C6 $5. All items are new limited stock items and are supplied in their original cartons. Enquire about reduced quantity prices. (Item No. 0136 + item details) Get rid of the dreaded memory effect Build this nicad battery discharger occurs when you recharge a partially charged battery repeatedly. This fools the battery into thinking that it was fully flat before you started charging it, even though it wasn't. When you use it next, the battery only discharges to the point from which it was charged and then stops delivering current as though it had gone flat. CROZMAN Thus, the capacity of the battery is vastly reduced and this leads to a constant S0mA for a period of 14 hours corresponding reduction in operation for a standard charge, although they time. can be fast charged if certain precauThis is the reason why so many tions are taken. people have trouble with nicads. They In either case, they should be fully use their camcorder to shoot half an discharged before you start to charge hour of the kids playing under the them if the best performance is to be sprinkler, then later want to shoot an obtained. If they are not correctly dis- hour of the kids playing local compecharged, the dreaded "memory effect" tition football. So they put the camcomes into play. corder on charge so that it will be "fully charged", ready for the footMemory effect ball. Little do they know that they The memory effect in nicad cells have just shortened the discharge time of the battery. Similar problems occur when people recharge parCOMPLETE tially flat nicad packs from LED1 04 mobile telephones. 1N4004 Our Nicad Discharger is both the prevention and the cure for the "memory effect" problem. It is powered by the battery under discharge and Are you having battery problems with your video camera or mobile telephone? This low cost device will solve your problems. It will correctly discharge a nicad battery pack so that it can then be recharged to full capacity. By MARQUE People with mobile telephones or camcorders often rush out to buy a new battery pack in the belief that the one they have is a "dud". This is often a complete waste of money. In many cases, the "dud" battery is still OK and just needs to be revived. Nicad batteries are rather touchy things when it comes to recharging. They like to be recharged by a constant current that is 1110th their full discharge capacity. For example, S00mA cells should be charged at a a~m~v DISCHARGE NICAD DISCHARGER 22 SILICON CHIP A0ADJ VIEWED FROM BELOW Fig.1: the circuit is powered by the battery under discharge. The battery voltage is fed to a voltage divider, sampled by S1 & compared using ICla with a 2.5V reference from ZDl. ICla then drives constant current source Ql to discharge the battery, while IClb drives the DISCHARGE indicator LED. PARTS LIST The Nicad Discharger can be used with standard battery packs ranging from 6V to 12V. By correctly discharging a battery pack, you get rid of the memory effect & this allows the pack to be recharged to its full capacity. prevents the memory effect from occurring by discharging the pack to its correct endpoint voltage before you connect it to your charger. It can also restore older battery packs to their former glory by a method called deep cycling. Deep cycling of nicads is carried out by charging and then fully discharging the battery repeatedly. The reason for doing this is to eliminate any memory effect present in the battery. A few cycles is enough to rejuvenate most battery packs but really stubborn ones may take longer. 1 PC board, code SC14207921, 80 x 45mm 1 Dynamark front panel label, 45 x93mm 1 metal diecast case, 98 x 50 x 25mm 1 single-pole 5-position rotary switch 1 400mm length of medium duty figure-eight cable 1 19mm plastic knob 1 red alligator clip 1 black alligator clip 2 LED mounting bezels 1 TO-220 insulating kit (mica washer plus insulating bush) 1 cordgrip grommet 1 machine screw, nut and lock washer 5 PC stakes 1 10kQ linear trimpot (VR1) Semiconductors 1 LM358 dual op amp (IC1) 1 LM336-2.5 2.5V voltage reference (IC2) 1 BD679 NPN Darlington transistor (01) 3 red LEDs (LEDs 1,2&3) 1 1N4004 diode (D1) 3 1N914 diodes (D2,D3,D4) Polarity reversal Our Nicad Discharger discharges batteries at a constant 200mA to this endpoint and then indicates (via a LED) that the pack is fully discharged. Five voltage settings are provided to accommodate different battery packs: 6V, 7.2V, 8.4V, 9.6V and 12V. To use the unit, you simply select the rated voltage of the battery pack and connect the flying leads. The DISCHARGE LED now comes on to indicate that the battery pack is discharging. When the endpoint is reached, the COMPLETE LED lights to indicate that the battery can be recharged and the DISCHARGE LED then goes out after a delay of several minutes. When nicad batteries are connected in series and discharged as a pack, the weakest cell will always be the first to fully discharge. If the discharge then continues, the weakest cell will be recharged by the others and this will cause it to reverse polarity, thus leading to permanent damage. To avoid this risk, an endpoint voltage is chosen for the pack. This represents the point at which all the cells have virtually totally discharged but occurs before any damage can occur to the weakest cell. In practice, this endpoint voltage is 1.1 V per cell (note: nicad cells maintain a virtually constant output voltage until they are fully discharged). Thus, for a 7.2V battery pack, the endpoint is 6.6V. constant 2.49V output using VRl. the two associated diodes, Dl and D2, The circuit is based on ICla, a corn- . provide temperature compensation for parator wired with a small amount of the voltage reference. positive feedback (via an 820kQ resisIf the battery voltage is above the endpoint voltage, pin 1 ofICla will be tor) so that it acts as a Schmitt trigger. The hysteresis produced by this posihigh and thus Darlington transistor Ql will be on. Note the presence of tive feedback stops the circuit from oscillating at the transition point. Fig.1 LED 3 and D3 in series between Ql's shows the details. base and the negative rail. These comAs shown, the battery voltage is ponents form a zener diode so that Ql applied to a resistive divider string acts as a constant current sink to-discharge the battery. via reverse polarity protection diode D4 and tapped off using switch S1. The way in which this works is as This tapped voltage is then fed to pin follows. Because the voltage on Ql 's 3 ofICla and compared with the volt- base is held at approximately 2.3V when pin 1 of IC la is high, it follows age generated by ZDl. that Ql 's emitter must be at about 1V ZDl is an LM336-2.5 voltage refer(since Ql is a Darlington transistor). ence which is adjusted to provide a Resistors (0.25W, 1%) 1 820kQ 1 750Q 1 5.1kQ 1 620Q 1 4. ?kQ 1 560Q 1 2.4kQ 1 470Q 1 2.2kQ 1 4.?Q 1W 2 820Q Circuit details JULY 1992 23 Fig.2(a): install the parts on the PC board as shown here but note that Qt, LED 1 & LED 2 must first be mounted on the case lid (see text). Fig.2(b) at right is the full size etching pattern for the PC board. Thus, a constant 213mA (approx.) discharge current flows through the 4. 7.Q 1W resistor while ever pin 1 of IC1a is high. (Note: LED 3 and D3 were chosen in preference to a conventional zener diode because they give a much sharper knee characteristic). MICA INSULA TIIG WASHER -jl:Q ' T0220 DEVICE Comparator IC1b is wired in parallel with IC1a. Its output (pin 7) is high when IC1a's output is high and this drives the DISCHARGE LED (LED 2) . When the battery subsequently discharges to its endpoint, pin 1 of IC1a switches low. This turns Qi off to end the discharge cycle and lights LED 1 to show that the discharge cycle has been completed. Both LEDs will now be on until, after a delay of several minutes , pin 7 of IC1b also switches low and turns LED 2 off. Note that a separate feedback resistor is not necessary for IC1b. That's because IC1b derives its positive feedback from the resistor across IC1a. Construction LID Fig.3: mounting details for the BD679 Darlington transistor. It must be isolated from the lid of the case using a mica washer & insulating bush. Smear both sides of the mica washer with heatsink compound before bolting the assembly together, then bend the leads of the transistor down to mate with the .stakes on the PC board. Construction is straightforward as all the parts are mounted on a small PC board coded SC14207921. Fig.2(a) shows the wiring details. Before mounting any of the parts, check that the switch fits into its holes on the PC board. Enlarge the holes to 1mm diameter if necessary. The resistors and diodes can now be installed on the PC board as shown in Fig.2(a). Make sure that the diodes are correctly oriented. The 4. 7.Q 1W resistor is mounted slightly proud of the board to aid heat dissipation. PC stakes are required to terminate the Darlington transistor leads and the battery leads. These should be soldered in next, followed by voltage reference ZD1, IC1 and the trimpot (VR1). Note that the flat side of the voltage reference faces the switch, while pin 1 of the IC faces away from the switch. Push these components as far down onto the board as they will comfortably go before soldering their leads. LED 3 can be installed next. This goes in next to the switch and should be mounted as close to the board as possible so that it doesn't later foul the lid of the case. Note that, unlike the other two LEDs, LED 3 is enclosed in the case. Don't put the other two LEDs in yet; we'll come to those later. The rotary switch needs to be the sealed PC-mount variety, as the open types are too deep to fit in the case. As purchased, the switch will have 12 positions but can easily be changed to a 5-position type by moving the locking ring at the front (behind the mounting nut). Check that the switch is RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 0 0 24 No. 1 1 1 1 2 1 1 1 SILICON CHIP Value 4-Band Code (1%) 5-Band Code (1%) 820k.Q 5.1 k.Q 4.7k.Q 2.2k.Q 820.Q 750.Q 620.Q 560.Q 470.Q 4.7.Q grey red yellow brown green brown red brown yellow purple red brown red red red brown grey red brown brown purple green brown brown blue red brown brown green blue brown brown yellow purple brown brown yellow purple gold brown grey red black orange brown green brown black brown brown yellow purple black brown brown red red black brown brown grey red black black brown purple green black black brown blue red black black brown green blue black black brown yellow purple black black brown yellow purple black silver brown TABLE 1 Battery Voltage Endpoint Voltage 6V 5.5V 7.2V 6.6V 8.4V 7.7V 9.6V 8.8V 12V 11 V seated properly against the board before soldering all the pins. The PC board can now be put aside while the necessary holes are drilled in the metal diecast case. First, attach the adhesive label to the lid, the drill holes to accept the rotary switch, the bezels for LEDs 1 & 2, and the mounting screw for the Darlington transistor. The hole for the rotary switch is best made by first drilling a small hole and then enlarging it using a reamer. The hole for the transistor mounting screw should be in line with the collector pin on the PC board and about 20mm from the lefthand edge of the lid (see photo). You will also have to drill a hole in one end of the case to accept a cordgri p grommet for the battery leads. Fig.3 shows the mounting details for the Darlington transistor. It must be electrically isolated from the lid of the case using a TO-220 mounting kit (mica washer plus insulating bush). Make sure that the mounting area is free of metal swarf and smear heatsink compound on both sides of the mica washer before bolting the assembly together. The leads of the transistor are then bent at right angles so that they mate with the PC stakes on the board. The indicator LEDs can now be pushed into their bezels on the lid. Orient each LED so that its anode (longest) lead is closest to the outside of the panel. This done, mount the board on the lid by sliding the leads of the LEDs into their mounting holes and doing up the lock nut of the rotary switch. Finally, solder the LED leads, cut off the excess lead lengths, and connect the leads of the transistor to their matching PC stakes. All that remains now is to connect This view shows the PC board after the lid has been removed (in practice, Ql & LEDs 1 & 2 are mounted on the lid first, as described in the text). LED 3 is pushed all the way down into the board, so that it sits below the switch body. The PC board is secured to the lid of the case by the switch, indicator LEDs & the mounting screw for Ql. Make sure that Ql's tab is correctly isolated from the lid (see Fig.3) before completing the assembly. the battery leads. These are made from a short length of medium-duty figure8 cable terminated with alligator clips. Secure the free end of the cable to the case using the cordgrip grommet and connect the positive and negative leads to the board as shown in Fig.2. Test & calibration To test the unit, first check the wiring and component orientation carefully, then connect a variable power supply in the place of the battery under discharge. Set both the supply and the Nicad Discharger to 12V, then slowly wind the supply back to see if the LEDs change state. If they do, then everything is OK. If they don't, go back and recheck the circuit board for errors. Finally, the unit can be calibrated by setting the supply to 11 V and adjusting VRl until the DISCHARGE LED just goes out and the COMPLETE LED just comes on (note: leave the Nicad Discharger set to 12V during this procedure). The remaining four ranges can then be checked. They should be very close to the cut-off points shown in Table 1. SC ]ULY1992 25 NEW RELEASE NEW RELEASE NEW RELEASE NEW RELEASE NEW RELEASE NEW RELEASE NEW RELEASE NEW RELEASE • • • • • • • • NEW RELEASE NEW RELEASE NEW RELEASE NEW RELEASE NEW NEW NEW NEW • • • • NEW RELEASE NEW RELEASE NEW RELEASE NEW RELEASE • • • • NEW RELEASE NEW RELEASE NEW RELEASE NEW RELEASE TEST EQUIPMENT Score top marks for quality, excellence and valuel Don't miss our great ra nge of new release test equipment at a store near you. New Release! New Release! DIGITAL ENGINE ANALYSER DIGITAL CAPACITANCE METER A sturdy and well constructed engine analyser in safety yellow for do-ityourself car service and maintenance. It's designed for checking the RPM , dwell angle, points as well as the battery charging system. With a large LCD screen, automatic zero adjustment, automatic polarity switching , 0.4 second sampling time , soft carry case, tilt stand and test leads. Cat Q-1554 A portable capacitance meter in safety yellow which has a large 3.5 digit LCD screen. Use it to check tolerances, sort values, select precision values. measure unmarked capacitors and select matched sets. Complete with tilt stand, test leads and a 9V battery for up to 200 hours of operating use. In addition, an onscreen battery indicator tells you when your battery needs replacing. With zero capacitance adjustment knob, push-free rotary range selector, '+' & '-' input connectors, capacitance range of 0.1 pF to 20mF and a protective soft carry case. $119 12 Month Warranty Features 3.5 digit display DC V 2V, 20V, 200V, 1000V AC V 2V, 20V, 200V, 750V ACA/DCA 2mA, 200mA, 20A Tacho 4, 5, 6 & 8 Cylinders Dwell 4, 5, 6 & 8 Cylinders Resistances 200, 2K, 20K, 200K, 2M, 20M , 200M Diode and Continuity Test $129 New Release! LOGIC PROBE 1.2GHz HANDHELD DIGITAL FREQUENCY COUNTER A high quality logic probe that's ideal for troubleshooting and analysis of logic circuits. It's switch selectable for TTL or CMOS circuits to give the correct threshold for each. The maximum input signal frequency is 20MHz. With deluxe Hi/Low (red/green) LED indicators, a 3mm Pulse/Memory LED and audible Logic Hi/Lo/ Pulse logic indication. As well, it comes with a figure 8 moulded power lead with small alligator clips and can be powered by the circuit under test (4-18V DC). An unbeatable low price! Anywhere else and you'll be paying a whole lot more for this incredibly easy to use 10Hz to 1.2GHz frequency counter. It has an 8-digit LED display and 3 switchable gate times. Comes with a rechargeable battery and a DC power socket, so you can work while you recharge it at the same time. What's more, it takes only 5 hours to recharge and has overcharge protection. It's ideal for measuring radio frequency transmissions and servicing stereos, videos, computers and cordless phones. With Hi and Low BNC frequency connectors and a full 12 month warranty . $ Cat Q-1320 Specifications CatQ-1224 12 Month Warranty Range B 199 Cat Q-1274 $3695 LOGIC PULSE Exceptional quality and value! A very effective and inexpensive tool for inspecting logic circuits . Can be used to inject a signal into logic circuits without removing components or breaking the circuit. The short 10us duration of the output pulse (100mA) insures that no damage will be done to the circuit. The output is switchable between 0.5 & 400Hz. It's powered by the circuit under test (5 -15V DC) and has a figure 8 moulded power lead with small alligator clips. $ 3295 Cat Q-1276 Range A 20MHz - 1200MHz Frequency Range 10Hz - 20MHz Impedance 1 MEG Ohm,80pf 50 Ohm 5Vp-p Max. Voltage 100Vp-p Gate Time: 2s, 0.02s, 0.002s Switch Selectable Read Out: KHz or MHz Power: 8.4V·rechargeable battery or optional 12V/500mA adaptor, Cat M-9627 B1334/c Qualitlj (JlBLES J0-60.%0FF! Get more cable for your money! All this month you'll save an incredible 30 to 60% off selected cables. Hurry into Dick Smith Electronics and check out our great range of cables today. Figure 8 marine cable. It's double insulated with tinned copper conductors to resist corrosion. Was $2.95m. 9 5m Cat W-2029 $1 100m or more $1 .45m 'Musiflex' twin shield professional audio cable. A low capacitance, flexible twin core cable with a conductive plastic shield for superior screening and faster wiring. Was $2.45m Cat W-2044 Single core double insulated. 1/113 240V 10Acable. Was SO~m. 26 colour flat ribbon cable of 10 x 0.12mm conductors. Was $4.95m CatW-2064 CatW-2047 100m or more $1.95m 100m or more $0.30m s195m 100m or more $1.25m 3 Core 240V textile cable. Was $1.95m $ lOm 5 Core Flat - Austel Permitted Cable. Was $1.75m. CatW-2054 CatW-2122 1 100m or more 95Cm s12sm 100m or more 95Cm RG 11/U professional quality low loss 75 OHM coax cable. Was$3.95m • CatW-2083 100m or more $1.00m · Cable stocks strictly limited. Some cables may not be available in all stores. . . Temperature Controlled .,. SOLDERING STATION Get stuck into this for value! A bargain priced 16V 310°C soldering station thars ideal for working with sensitive electrical components. The iron operates from a 16V transformer and has a positive temperature coefficient heater which maintains the tip at a constant 310°C. What's more, it has an insulated coolgrip handle, long lasting fine tip which delivers maximum heat right at the tip. With large capacity sponge tray and a built-in stand. s499s 81334/a 25%0ff CORD WINDER Cord Winder has a 11.Sm cable with two power outlets in one handy unit. Includes in-built 10A circuit breaker. Cat M-7092 CORD STICK Exceptional value! Makes winding and . storing extension cords a breeze! Suitable for cords 16m and over. Cat M-7090 $1 2 95 OUR KITS SAVE YOU '- Build it yourself and save! Right now you'll find a fantastic selection of new release kits at a store near you. See them today! PULSE QQQ[t] GENERATOR KIT ELECTRONIC DOORBELL Q A quality doorbell system which won't cost you the earth! In fact, it's so good you'll have a hard time convincing friends and family that you actually built it yourself. It's a full form kit and comes complete with a two-tone bell generator.easily replaceable components, doorbell switch, battery holder cable and a stylish deluxe doorbell case. Cat K-3800 A professional quality.yet affordable generator. You'd expect to pay a whole lot more for a commercial unit with similar features. It's ideal for evaluating wideband amplifiers and filters, adjusting the frequency compensation of scope probes and developmental work in digital circuits. It has a frequency range of 1Hz to 1MHz, single-shot, an adjustable pulse width from 350ns to 100ms and adjustable delay on the main output. What's more, it has variable output pulses from 1V to 10V, a choice of either positive or negative output polarity selectable AC/DC coupling and is mains powered. A full form kit with all components, hardware. pre-punched screened front panel and a deluxe case. ss99s Cat K-7342 VOLTAGE REGULATOR Q R FOR 2WAY SPEAKER SYSTEMS Q Improve your loudspeaker's performance. This crossover kit has features usually found 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. This gives 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 . s2995 Cat K-5405 SOLAR EDUCATION KIT Q Harness the sun! A fun and inexpensive way to learn about solar energy. It's ideal for children and high school science projects. Learn how to construct projects powered solely by the sun's energy. The kit contains a solar cell module, a solar powered motor, wires, plastic turn-tables and an easy to read booklet explaining solar energy. Power almost any battery operated device from a car battery or DC plug pack supply and save batteries! This safe and low-cost kit regulates a +12V(nominal) from a plug pack or battery. By changing the resistor value on the PCB you can step-down voltage to 3V, 4.5V, 6V, 9V or other voltages within the range . This device (the LM317) is capable of delivering up to 1.5A (with heatsinking) has an output voltage range from 1.2 - 37V and features internal thermal overload and short circuit protection. What's more, you can design it for existing equipment or as a stand alone unit. Short form kit with all componentc and PCB. Cat K-1060 Cat K-3592 TV TRANSMITTER FOR VIDEO RECORDERS QQ MAJOR DICK SMITH ELECTRONICS AUTHORISED.STOCKISTS: NSW: ARMIDALE: New England Electronics 711655 BALLINA: Ballina Electronics 867022 BATEMAN'S BAY: Baycity !.ght & Sound 725030 BATHURST: Electronic Frontiers 323933 BERMAGUI: Oztech Electronic 1 Products 934242 BOWRAL: Bowral Electrical Supplies 611861 BROKEN HILL: Hobbies & Electronics 884098 COOTAMUNORA: Cootamundra Music & Ute 422561 CCffS HARBOUR: Coifs Harbour Electronics 525684 OENILIQUIN: Deni Electronics 813672 DUBBO: Chris's Hi Fi 828711 FORSTER: Forster Village Electronics 545006 GOULBOURN: Tunlive 22 1288 GRAFTON: Repairs & Spares 421911 GRIFFITH: Miatronics 624534 INVERELL: lnverell Electronics 221821 KEMPSEY: P&L Leonard 631134 LEETON: Leeton Audiotronic 532800 LIGHTNING RIDGE: Lightning Ridge Solar Power291013 LITHGOW: Oouroy Photographics513173 LISMORE: If you own a VCR and more than one television here's a great idea. This Decro Electronic Services 214137 MOREE: Moree Electronics 522091 MUDGEE: Headware 723895 transmitter lets you play a video and watch it from another television without MURWILLUMBAH: Strings & Things 723684 NARRABRI: Namoi Computer Service 923274 NELSON BAY: connection leads from the VCR to TV. What's more, it comes with a quality plug Nelson Bay Elect & Hobbies 613685 NOWRA: Nowra Electronics 210722 PARKES: Strad Music Cir 623366 pack (valued at $21.95) making this kit exceptional value! As well, all components PORT MACQUARIE: Hastings Computer Service 640255 RICHMOND: !.!icon Crafts 764101 TAREE: Manning for UHF or VHF modulator output are included. It's easy to construct and comes Electronics 512233 ULLAOULLA: Coastal Electronics 553989 WAGGA WAGGA: Phillips Electronics 216556 WALGITT: Walgett Electronic Centre 261116 WELLINGTON: Wellington Service 452325 WINDSOR: Silicon as a full form kit with PCB, all components and front panel label. You'll have to Crafts 776722 VASS: Wanmington Electrical 261116 YOUNG: Keith Donges Electronics821279 VIC: ARARAT: build your own antenna, so PCB's and instructions are also included. Jerram Electronics 522345 BAIRNSOALE: LH & LM Crawford 525677 BENALLA: North East Electronics 622710 CASTLEMAINE: Inspect Electrcs 723773 COLAC: Colac Electronics 312647 ECHUCA: Echuca Cat K-5700 Technical Services 822956 MILOURA: Pullman Auto Pro 232882 SHEPPARTON: Andrew Guyatt Electronics 219497 SWAN HILL: Nyah □;strict TV Service 329303 WARRAGUL: Roylaine 234255 WARRNAMBOOL: Koroit St Elec Services 627417 WONTHAGGI: South Gippsland Photo Service 721411 Ol.D: AYR: Delta Electrix 631566 BLACKWATER: Cool Tronics 625827 BOWEN: Delpro Aicies 66 3477BUNOABERG: Bob Elkin Electronics 521785 CALOUNORA: Electro-mart 916533 DYSART: rt Videotronixs 562107 GLADSTONE: Electronic Enterprises 726660 INGHAM: Masons Electronics 7 188 INNISFAIL: lnnislail Hi.fi 612014 KINGAROY: MO & MM !.egle 624535 MACKAY: Stevens Electronics 511723 MARYBOROUGH: Keller Electronics 214559 MT ISA: Outback Electronics 433331 NAMBOUR: Nambour Electronics 411966 PIALBA: Keller Electronics 263749 STANTHORPE Granite Belt Communications 813333 TAS: BURNIE: Electronic City 314760 OEVONPORT: Al Electronics 246322 LAUNCESTON: Kitronics 344555 SA: MT GAMBIER: Hutchesson's Communication 250400 PORT LINCOLN: Basshams TV & Comp World 630075 WHYALLA: Eyre Electronics 454764 WA: ALBANY: Micro Electronics 412077 BUNBURY: Micro Electronics 216222 GERALOTON: Batavia & Electrical 211276 KALGOORLIE: Toda~•s Electronics 215212 KARRATHA: ~~bJ~:%fJ!ff'ies 6 MANOURAH: Mandurah Hi Fi 5812 06 PORT HEOLANO: Ivan Tomek ~ NE,92: Includes Plug Pack Li= MORE THAN EVER ... You'll find more high quality components, more new books and more value than ever before at Dick Smith Electronics! July Special July Special TIPS & TECHNIQUES FOR THE ELECTRONICS HOBBYIST MASTERING IC ELECTRONICS Gordon Mccomb - 270 pages. A concise reference guide to electronics with everything from parts & supplies to safety tips in the workshop. An essential introduction to electronics, with straight-forward answers to the most commonly asked questions. Joseph J Carr Principles and practical experiments designed to give you all the information you need to become familiar with the theory and use of IC circuits. Learn about component specifications, design standards and IC applications. Cat B-1600 Cat B-1612 NEW Now Only $2995 Now Only $3495 ZENER SCHOTTKY & RECTIFIER DIODES SCR'S & TRIACS Ill . B .,:,, Covers 4000 Series IC COS/MOS B-SERIES DEVICES Over 860 pages of information and data sheets on the SGS-Thompson range of CMOS B-series integrated circuits. With the latest product features and technology. Cat B-5560 July Special SMALL SIGNAL //f.i.i•;), TRANSISTORS :1 , , .~: DATABOOK i_i: II -- ►c► /. ! ,,; ......,_ ~ 512 pages A comprehensive cross-reference index for the latest industry standard components and SGSThompson's direct/closest replacement. With data for over 740 Thyrister devices from Small Sensitive Gate SCR's to Alternistors and Trigger Diodes. Ideal for people who work with Zener Diodes, Schottky Diodes or Rectifier Diodes. Includes data covering many products across the diode range, selection guides and cross references to industry parts and numbers. Cat 8-5566 Cat B-5568 $24 9 5 Cat B-5564 420 pages of data covering a range of SGS Thompson 's discrete devices for small signal, consumer, industrial and professional applications. It also lists data for RF devices and is ideal for evaluating product performance in relation to equipment design. Now Only $1995 KNOBS & TRANSISTORS TNC Plug for Cellular Phones Cat P-2390 New Low Price $395 40mm Hi-Fi Knob (Anodized Black) 30mm Hi-Fi Knob (Anodized Black) 20mm Hi-Fi Knob (Anodized Black) Cat P-7110 Cat P-7112 Cat P-7114 NEW NEW NEW PN 100 G.P Amp/Switching Transistor MultiReplacement Type For a Wide Range of Transistors PN200 as above in PNP Cat Z-2000 Cat Z-1000 This Month Only NEW I This Month Only NEW BUK 456-60A N-Ch Power Mosfet, 52 Amps, High Power Replacement for BUZ 71, used in 12V-240V voltage inverters BUK457-600B N-CH Power Mosfet, 600V as used in most switch mode power supplies in computers, TV sets, monitors etc. Cat Z-1852 Cat Z-1854 NEW NEW TIP 142 NPN Power Darlington Output TIP 147 PNP Power Darlington Output Cat Z-2026 Cat Z-2028 NEW NEW DS XPRESS PHONE & MAILORDER SERVICE Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105 FAX: (02) 805 1986 or write to DS XPRESS, PO BOX 321 N/ RYDE NSW 2113 All Major Credit Cards Accepted. O/ Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS PC 16450CN high speed Uart with band generator for 286 PC/ AT C-16550 AFN high speed Uart with band generator for 386/ 486 Cat Z-9116 Cat Z-9117 $4995 STORE LOCATIONS: NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 871 7722 • Brookvale905 0441 • Bondi 3871444 • Campbelltown 27 2199 • Chatswood Chase 4111955 • Chullora 842 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby New Location 17-19 Florence St 477 6633 • Hurstville580 8622 • Kotara 58 2092• Liverpool 800 9888 • Maitland 33 7888 • Miranda 525 2722 • Newcastle 811898 • Nonh Ryde 878 3855 • Orange 818 400 • Parramatta 689 2188 • Penrith 32 3400 • Railway Square 211 3777 • Sydney City 267 9111 • Tamwonh 661711 • Wollongong 28 3800 ACT• Belconnen (08) 253 1785 • Fyshwick 280 4944 VIC • Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0899 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2386 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 326 6088 & 246 Bourke St 839 0398 • Richmond 4281814 • Ringwood 879 5338 • Springvale 547 0522 QLD • Booval 282 8200 • Brisbane City 229 9377 •Buranda 391 8233 • Cairns 311 515 • Capalaba 245 2870 • Chermside 359 8255 • Rockhampton 27 9844 • Southpon 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 • IA • Adelaide City 232 1200 • Beverley 347 1900 • Elizabeth 255 6099 • Enfield 280 6088 • St. Marys 277 8977 WA • Cannington 451 8666 • Fremantle 335 9733 • Penh City 481 3261 • Midland 250 1480 • Nonhbridge 328 8944 TAI• Hoban 31 0800 NT• Stuan Park 811977 STORES ACROSS AUSTRALIA AND NEW ZEALAND Eight S ta-tion '~ vr· . controller Sprinkler . Take the drudgery out of watering your garden with this versatile 8-station Sprinkler Timer. It has 32 programmable start & run times & can also be used to control lights or other appliances . ({if:, . t;d By GRAHAM BLOWES 8-STATION AUTOMATIC SPRINKLER CONTROLLER A RE YOU TIRED of running outside to shift the hose onto the next group of plants? Do you trust your neighbours to water all your garden properly while you are on holidays? Do you have plants that need to be watered more than once a day and others that only need watering once a week? Well, fear no more because this little gadget will solve your problems. It is completely bullet-proof when it comes to power failures and has all the features of the expensive models that are on display at nurseries and 30 SILICON CHIP specialised plumbing suppliers. It is also simple to drive, as there are only four buttons to worry about, and it has a large, easy to read display. Most other controllers have a small 4-digit display and many confusing buttons. Also, many of these controllers work in a sequence. Once the start time has been reached, station 1 will turn on, followed by station 2 when station 1 's run time has expired. You don't have a choice! It's either all or nothing! By contrast, this automatic sprinkler controller allows you to selec- tively water any area of garden as little or as often as you like. It has other uses too; eg, as a security light controller or as a generalpurp9se timer. And although it normally runs off a 24VAC plugpack supply, it can also be made to run off 12V DC, as explained elsewhere in the text. Heavy duty relays wired externally could then be used as slaves to the relays on the PC board for switching the lights on and off. Alternatively, you could delete the internal relays, run a link between pins 3 and 5 of each relay position, and use heavy duty, externally wired 12V relays driven directly from the relay driver (IC5, ULN2803). In standard form, the on-board relays are used to switch up to eight water control solenoids (available from gardening suppliers). In addition, an optional ninth relay (RL9 on the circuit) can be used to con,trol a master solenoid. This master relay can be wired to turn on when ever any or just some selected stations turn on. Each station can be operated up to four times a day (or as little as once every 14 days) and the ontime (run time) for each cycle can be set from 1-99 minutes. A complete list of features is given below in Table 1. As you can see from this list, the unit compares favourably with the Richdel controllers which are available for about twice the price. The Hardie Pope and Cardena units available at department stores are sequencers only (ie, the next station starts when the previous one finishes). You cannot have separate start times for each station or cycle, as you will have discovered if you bought one. They are also messy to set up and only have very small displays. Button functions 0 Eight Station 0 0 Sprinkler Controller 0 Time Date T--,-- - _J T L _ Run ,__ _ _ _ _ start Start Sprink~ Cycle~ Day 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 €)• 1<at>• S l -->S8,Time Fig.1 shows the layout of the front panel controls. There are just four pushbutton switches to operate: Sl-S4. It might look complicated at first glance but it 's really very easy to drive as we shall see. Button 1: Sl is the MENU switch. Each time it is pressed, the next sprinkler number will show under the flashing cursor, immediately to the right of the "S". Following sprinkler 8 (SB on the display), the time setting menu. appears. This looks exactly like the default display, except that the colon does not flash and the cursor is over the HOUR setting. Pressing Sl again then takes you back to the default display. Button 2: S2 is the CURSOR key. Each time it is pressed, the cursor moves to the next field to the right. There are six fields: Sprinkler, Cycle, Day, Time Min. Hour Time Display * ... Program 0 0 : -. I0a:23 09: 11 :921 Auto mode on/off All active stations off display • Auto ... Manual Any <at>• other _. Is rn 1 01 08: 10:201 0 on/off single station on/off position single ... station : *is+, IS - 0 Fig.1: this front panel layout shows the four control switches. TABLE 1: MAIN FEATURES (1 ). Controls up to eight solenoids plus a master solenoid. (2). Each station can have up to four cycles (ie, up to four start times a day or as seldom as one every fortnight). (3). Each station (and cycle) is completely autonomous, which gives a possible 32 programmable start times. (4). Run time: minimum - 1 minute per cycle; maximum - 99 minutes per cycle. (5). LED indication of station status. Red LED= auto mode active; Green LED= solenoid active; All active red LEDs flash in "Rain Off" mode. (6). Manual on/off control for each solenoid. The run time of cycle 4 is also used here to provide an automatic cut-off feature. This lets you manually switch on the sprinkler and forget it. The sprinkler will then automatically turn off after the run time of cycle 4 has expired. (7). Rain mode (deactivates all automatic cycles while saving program settings). (8). All settings are stored in an EEPROM (X24C04) and the time is supplied by a real time clock IC (PCF8573). Battery backup is provided by a small lithium cell for the clock, which will last for about one year if the power is left disconnected for that long! The settings memory is good for 100 years. (9). When power is restored after a power failure, all appropriate solenoids are enabled and the various cycles completed. (10). Uses Motorola 68705P3 microcontroller. (11). Runs from a single 24VAC, 1A plug pack supply. (12). Uses a 16 x 1 liquid crystal display (LCD) to show time and sprinkler settings. Default display is the current time and date. JULY 1992 31 TABLE 2: SPRINKLER SETTING MODE FIELD FUNCTION COMMENTS 1 Station (1 - 8) Selected by pressing switch S1 . S3 toggles the automatic mode on or off for the station indicated; S4 toggles the selected station solenoid manually. 2 Cycle (1 - 4) This sets the number of cycles that occur during the day for any one station. Set using S3 or S4 3 Day (01 - 14) 01 means turn on every day; 02 means turn on every second day, etc. A display of -- means cycle off. Incremented using S3; decremented using S4 4 Start Time Hours (00 - 23) Incremented using S3; decremented using S4 5 Start Time Minutes Incremented using S3; decremented using S4 (00 - 59) 6 Run Time Minutes (00 - 99) Incremented using S3; decremented using S4 Note: each successive field is selected by pressing S2. Hour, Minute and Run Time. The cursor will cycle back to Field 1 (Sprinkler) after the button is pressed at the last field (Run Time). Field 1 of the sprinkler setting mode is explained below, under the heading "Buttons 3 & 4". Table 2 lists the remaining fields and their functions in the sprinkler setting mode, while Table 3 lists the fields in the time setting mode. Buttons 3 & 4 : these buttons have several functions, depending on whether the unit is in the sprinkler setting mode or in default mode (time and date display). In the sprinkler setting mode , if the cursor is flashing over the number immediately to the right of the "S", S3 toggles the automatic mode on or off fo r the station indicated (red LED on/ off) . S4 toggles the selected station solenoid manually (green LED on/ off). In any other field, S3 increments the setting and S4 decrements the setting. If either button is held down, then th e setting will increment/decrem ent automatically. The one exception is the Cycle field - it only cycles in th e one direction. When the Cycle field is incremented, all the fields to the right change to reflect the settings for that cycle. In the default mode, S3 toggles TABLE 3: TIME SETTING MODE FIELD FUNCTION 1 Hour (00 - 23) 2 COMMENTS Incremented by S3; decremented by S4 Date (00 - 31) Incremented by S3; decremented by S4 4 Month (00 - 12) Incremented by S3 ; decremented by S4 Year (00 - 99) Incremented by S3; decremented by S4. Note: does not automatically increase at 12 midnight on Dec. 31 due to lack of room in EEPROM Note: in the default mode, S3 toggles "Rain Off", while S4 turns off any manually activated solenoid. 32 How it works The software performs all the timing and display functions, so I won't go into that too deeply. ICZ and IC3 have a bidirectional serial interface built into them called an I2 C bus, which uses only two wires (see Fig.2). This is a Philips designed protocol. There are other systems such as SPI (Serial Peripheral Interface), a popular one that Motorola seems to favour. This latter interface is built into the more expensive Motorola microcontrollers. The microprocessor used here only has an 8-bit timer. The software includes all the routines for "talking to" and "listening to" the slave chips, as ICZ & IC3 are called. To talk to an IC on the I2C bus, a ST ART condition is sent out on the bus and all !Cs go into LISTEN mode. Minute (00 - 59) Incremented by S3; decremented by S4 3 5 "Rain Off". This causes any lit red LEDs to flash, to indicate that the automatic mode has been deactivated (a handy feature if you want to stop automatic watering due to rain). If S3 is pressed again , the automatic mode is re-activated with the original program settings. Also, in the default mode, S4 turns off any manually activated solenoid. This saves you from having to step to the particular sprinkler setting before pressing S4. The solenoid will also turn off automatically after the run time of Cycle 4 has expired, as explained previously. Set Cycle 4's run time to 99 if you don't want this to happen too soon. Cycle 4 was used for this function because it is unlikely to be used in real life. Note that all automatically operated sprinklers also turn off when S4 is pressed to turn off manually activated sprinklers in the default mode. These automatic sprinklers then turn on again a short time later (60 seconds max.) when the internal microprocessor receives its next interrupt signal. SILICON CHIP Fig.2 (right): the circuit is based on EEPROM IC2, a PCF8573 clock calendar chip (IC3) & a Motorola 68075P3 microprocessor (IC4). IC6 & IC7 latch the outputs of IC4 to drive the LEDs, while IC6 also drives the station relays via relay driver IC5. ► ~ ~ N co co ....-< t-< c:: ....... ~ 11 G~D 1 E'LJc B .,. 4 l 1 +5V ___ C9 27pf+ SPRINKLER TIMER ~K IC3 ISDA~ PCF8573 SC1 0 t15h .,. 8 7 TESTVCC 5 IC2 SDA 2 A1 X24C04. 6 1 A2 OV SCL L ~!?l , PA4 PA3 ' ' ":" VPP IC8 7555 06 18 015 I 28 PAS~ 07 05 17 07 06 05 04 03 02 ~ 0216 01• 5 5 4 ~~~: tth = LED9-16 8xGREEN 18 07 l7 06 14 05 02 8 03 74~i~74 13 D4 1 DO ~ K o IC5 ULN2803 110 _ (~~ J _ ®+ _A©i 8 7 6 5 4 3 2 1 ·LED1-8 8xRED r------+5V C1 50VW - 1000I,J; 11 .11 Jl .).! ~ ,12. JI 18 ,- R1 180Q 10W r~~~~"u'"'"' l 05115 REL6 -""1""0-~1.J 7 REL31 REL1 4R10-R17 RELB REL7 REL6 REL5 REL4 REL3 REL2 REL1 023 74HC374 IC6 03 9 REL~4~~W;~°'1~' ~DO ~01 !!!I 20 ~ CONTRAST VR1 50k I 11ICLK VC~2 +5V .ll 12 11 10 03 04 15 16 8 9 01 02 7 6 5 2 I 14 PA6~ 1N4148 1+ C15~ .,. .. LOU CONN 4 13 DO 12 PB7~ 9 PB6 PB5 PB4 PB3 PB2 PB1 PBO PA2 221 21 PA1 20 PAO J6 , RESET' GND IC4 68075P3 13 I EXTAL IITT 271PA7 4 47..r , R32 33k , 5 XTAL 24 23 E C13.l.i -:-- +5V 011 C10 +5V Rl 8} ..i t :i :rtt :: %i~ VIEWED FROMI BELOW i~I R '~"' 81 3Vi ! 0141 1N4148 MENU' S1 l +SV ··i:-i C2 " 47 -50VW. Pu3o .1,; ,ovw+ J!!!T C1i C18 +5V t ! 24VAC 01+ 01+ 0.1 1 .C16 +12V RL1 FBR211 F1 1A 1 1 X2 MK8/2 t X4 'f;j PARTS LIST 1 double-sided PC board, code SPV3, 133 x 82mm 1 pre-punched plastic case with screened front panel 1 battery holder, Bogan BH906-c 1 3V lithium battery (CR2032) 1 14-way PC connector strip 6 2-way PC mounting terminal blocks (Klippon MK8/2) 4 12mm spacers 2 6mm spacers 4 3mm insulating washers 1 heatsink (see Fig.4) 1 4MHz crystal (X1) 1 32. 768kHz crystal (X2) 2 fc90 inductors (L 1,L2) 1 28-pin IC socket 1 8-pin socket 4 momentary contact pushbutton switches 2 fuse clips 1 1A fuse (20mm) 9 miniature 12V SPOT PC relays (FBR211O012 or equiv.) 1 100kQ miniature horizontal mount trimpot (VR1) 4 15mm x 3mm-dia. machine screws & nuts 2 5mm x 3mm-dia. machine screws & nuts 2 8mm x 2mm-dia machine screws & nuts Semiconductors 1 7805 3-terminal regulator (IC1) 1 X24C04 EEPROM (IC2) 1 PCF8573 clock/calendar (IC3) 1 68705P3 microprocessor (IC4) 1 ULN2803 8-channel driver array (IC5) 2 74HC374 latches (IC6,IC7) . 1 ICL7555 timer (IC8) 3 BC547 transistors (Q1-Q3) 4 1N4004 diodes (01-04) 11 1N4148 diodes (05-015) 8 3mm red LEDs (LED1-8) Next, an 8-bit address is sent out (by IC4), to which the addressed IC will respond with an ACK (acknowledge) signal. The four MSB's (most significant bits) of the 7-bit address - Lhe 8th bit is read/write (R/W)- are "hardwired" internally to that particular chip (IC4). The next two bits (PA3 & PA4) of the address are brought out to external 34 SILICON CHIP 8 3mm green LEDs (LED9-16) Capacitors 1 1000µF 50VW electrolytic (C1) 1 100µF 10VW electrolytic (C3) 1 47µF 50VW electrolytic (C2) 1 4.7µF 10VW tantalum (C13) 21µF 10VWtantalum (C14,C15) 7 0.1 µF monolithic (C4C8,C 10,C11) 1 27pF monolithic (C9) 1 10pF monolithic (C 12) Resistors (0.25W, 1%) 1 10MQ (R26) 2 1MQ (R33,R34) 1 33kQ (R32) 10 10kQ (R18-R21,R23-R25, R27,R28,R30) 1 4.7kQ (R22) 21kQ (R29,R31) 8 820Q (R2-R9) 8 330Q (R10-R17) 1 180Q 10W (R1) Where to buy the parts A complete kit of parts, excluding the relays, is available for $125 plus $1 0 p&p. The relays are $3. 75 each (please specify number required). Alternatively, the following parts can be purchased separately: programmed 68705P3 $25 (V10 for 2-chip LCD, V13 for single-chip LCD); PC board (SPV3) $25; C24C04 EEPROM $8; PCF8573 clock/calendar IC $8; LCD (16 x 1) $16; plastic case (Rp3) with p,u nched screened aluminium front panel $20; relays $3.75. Please add $6 p&p without the plastic case or $10 with the case. Send cheque or money order to Graham Blowes, 38 Garnet St, Niddrie, 3042. Phone (03) 337 1917. Fax (03) 575 3369. pins. This enables you to have four clock chips and four EEPROM chips all on the one pair of wires. The 7th bit of the address is used as a page select (depending on the chip used) . After the address, you can either send or receive data. A STOP condition is sent out on the bus to terminate the transaction. The actual protocol/ signals are a story in themselves, so we won't go too deeply into that here. Power supply The 24V AC passes through inductors 11 and 12 to a bridge rectifier formed by diodes D1-D4. The resulting DC is then filtered by a l000µF electrolytic capacitor (Cl). 11 and 12 prevent any glitches generated by switching the solenoids from feeding into the DC supply. A relatively high voltage (37V DC approx.) is present across Cl, which has to be dropped down before it is fed to the regulator (ICl). A 180Q, 10watt resistor was chosen for this task. The voltage across Rl varies somewhat, depending on how many LEDs and relays are on at the time. With a 24V AC 1A plugpack, it is recommended that only one station solenoid plus the master solenoid be operated at any one time. The circuit by itself (no LEDs etc) requires 60-90mA, most of which is used by the microprocessor. The 12V relays operate over a fairly wide range (70% to 225% of rated voltage), so they are quite safe. If you try to operate too many relays at once, the voltage at the "low" end of Rl falls below that of the pull-in voltage of the relays, thus preventing too many solenoids from being operated at the same time and blowing the fuse. On the PC board layout (Fig.3), you will find space for an inductor called 13 (top lefthand corner). Originally, a 4 70µH choke was used here to do the job that 11 and 12 now do. It didn't work too well but I left the mounting position on the layout in case anyone has difficulties with glitches. The track between the mounting holes has to be cut for it to be used, however. Real time clock IC3 (PCF85 73) is the real time clock. This chip generates an interrupt every minute. When this happens, the microprocessor (IC4) reads the clock and the EEPROM and tests to see if any sprinklers should be on. The output from IC3 at pin 9 is not a pulse but a waveform that is high for 30 seconds and low for the next 30 seconds. Ql, Cl0, Cll, R27, R28 & R29 then turn this into a pulse every minute for the IRQ input of the microprocessor. Basically, Ql and its associated parts form a rising edge detector. When removing the appropriate diodes. Q3, C14, R34 & R23 form a timing circuit which holds the Output Enable (pin 1) of IC6 high during power up. This prevents the solenoids from momentarily operating during power up, before the microprocessor has initialized the port. At switch on, C14 pulls the base of Q3 close to Vee, turning Q3 on. Once C14 has charged (via R34), Q3 turns off and pin 1 of IC6 is held low by R23. IC7, another 74HC374 latch, is used to control the red LEDs. Note that the green LEDs have smaller current limiting resistors than the red LEDs. That's because green LEDs don't shine as brightly as red LEDs for a given amount of current. This view shows the top of the PC board with all components in position but with the heatsink removed from the 7805 regulator. Note that only four station relays plus the master relay (RL9) have been fitted here. pin 9 of IC3 goes high, Ql momentarily turns on via Cl 1 and pulls the IRQ pin of IC4 low. IC3 also has an inbuilt power fail detector. This automatically puts it in a power fail mode which keeps the clock running via the battery but disables the outputs. D13 prevents the battery from being used while 5V is present. Capacitor C12 (lOpF) can be replaced by a small trimmer capacitor (5-25pF) which is used to adjust the frequency precisely if required. This involves connecting a frequency meter to pin 11 of IC3 and adjusting the trimmer for a reading of 128Hz. In practice, a value of lOpF gives reasonable accuracy, especially for this application. TheEEPROM IC2 (X24C04) is an EEPROM with 512 x 8 bits storage space. This is used to store all the sprinkler settings as well as system status; ie which sprinkler(s) are in auto mode (red LEDs) and whether the system is enabled. This means that if the power were to fail and then come back on, everything would be as it was before the power failure. The system status and settings are read every minute while only the status is read at power up. The 7th bit of the address is used to select the upper 256 bytes or the lower 256 bytes. Watch dog circuit The watchdog circuit consists of Q2, ICB and their associated parts. The circuit around Q2 is the same as around Ql. PORT A BIT 7 (PA7) of IC4 is toggled up and down as long as the program is running in the main loop, which is continually polling the four pushbutfon switches. This action turns QZ on in sympathy with the action of PA7. Thus, Q2 continually discharges C13, which forms part of the timing circuit of IC8 (7555). IC8 is connected in the astable mode with a high duty cycle. While C13 is unable to charge up via R32 and R33 (due to QZ), pin 3 of IC8 is unable to go low. However, if PA7 stops toggling, Q2 will remain off, thus allowing C13 to charge and switch pin 3 of IC8 low. C15 now discharges via D15 , thus resetting the microprocessor. PA7 then starts to toggle during the high portion ofIC8's duty cycle, which keeps pin 3 of IC8 from going low again. If the microprocessor does not reset properly, it will receive another reset pulse from IC8. In reality, this circuit will only be used if a fast glitch on the mains causes the microprocessor to go into "mumble mode". Solenoid latch IC6 (74HC374) is the latch that is used to control the green LEDs. It also drives the solenoid relays (RL1-RL8) via IC5 (ULN2803). The master relay (RL9) is controlled by IC5 via an OR gate consisting of diodes D5-D12. As shown, RL9 will turn on if any of the other stations turns on but it can be left off for selected stations simply by Liquid crystal display The controller can be used with the two types of LCDs in common use. The different types can be easily distinguished by the number of chips on the display's PC board. The type with the two chips (usually a HD44 780A00 controller and a HD44100H LCD driver) uses Vl0 of the software and the single chip type (usually HD44780A00) uses V13 of the software. The 2-chip type is easier to use, as the data can be written to the display in 16-byte chunks. It is configured as a 1 x 16 character display, as you would expect. The single-chip type requires the display to be configured as a 2-line device and the data to be split into 8byte chunks. After the 8th byte has been sent, the DD RAM address has to be changed up a page, then the last eight bytes can be sent. In other words, the single chip type is treated as a 2 x 16 character display! If you already have a display, make sure you know what type it is before you order the programmed microprocessor. Trimpot VRl is used to adjust the contrast of the display, although the setting range is not very broad. Construction Those people who don't read instructions are advised to change their habits, especially for this project. It will be necessary to follow the exact procedure set out below to successfully build the Sprinkler Controller. The PC board measures 13 3 x 82mm JULY 1992 35 UNDER PCB 0 [] Fig.3: install the parts on the PC board as shown here but note that the four switches, the LEDs, eight resistors, trimpot VR1 & three capacitors go on the solder side of the board (see text). Note also that only the tracks on the underside (solder) side of the board are shown here for clarity. and is mounted on the lid of a Retex case (RP3). This board is double sided with plated through holes, and features a component overlay and solder mask. The front panel has been screen printed, punched and drilled to fit the PC board exactly. The PC board must be assembled using high-quality soldering techniques. You will require a soldering iron with a long pointed tip, as some of the solder pads are nearly hidden by the pushbutton switches. Sixteen LEDs, eight resistors, three capacitors, the four momentary pushbutton switches, contrast trimpot (VR1) and the LCD are mounted on the solder side of the PC board. Capacitors C5 , C7 & C8 are mounted first 36 SILICON CHIP (C6 is mounted on the silk screen side). Clip off the excess leads close to the board as soon as these parts are soldered in. Mount the pushbutton switches next (ie, on the side without the silk screen). Check that the flat side of each switch is oriented exactly as CAN BE CUT HERE TD DISABLE MASTER RELAY i°PERATIDN IC6 IC5 A A ~ 05 --012 I Fig.4: mount diodes D5-D12 as shown here so that individual diode leads can be cut to disable master solenoid operation for selected stations. shown in Fig.3. Also, make sure that the switches are sitting flat on the PC board before you solder their leads. After you've soldered them, trim their pins as close to the board as possible. The remaining parts on the solder side of the board are installed later on. It's now necessary to install most of the parts on the top of the board. Capacitor Cl can be installed first. It is placed directly above S2 and S4, with the positive side towards the outside of the PC board. Make sure that you don't damage the plastic of the adjacent switches when you solder the positive lead of Cl (remove the switch tops if necessary). It's also a good idea to clip the positive lead to length before installing the capacitor. Next, mount diodes D5 -D12 as shown in Fig.4. You can then decide later on whether or not the master relay (RL9) turns on when a particular station is activated. If you don't want the master solenoid to turn on for a particular station, just cut the lead to the relevant diode (eg, cut the lead to DB if you don't want the master solenoid on when station 4 is on). If all the diodes (D5-D12) are left in circuit, the master relay will turn on when ever any of the eight stations turn on. Resistors RZO & R21 can now be installed. Note that these parts must be installed end on. This done, install IC5, IC6 & IC7. The row of pins for IC5 that runs under S1 must be soldered from the top (IC side) of the board. In addition, pins 4, 5, 6 & 7 of IC5 must be shortened a bit before the IC is installed so that they don't hit S1. Pins 4, 5 & 6 of IC6 have to be bent inwards, so that they don't foul the case of S1. Note particularly that IC6 is installed the opposite way to that of IC7 and IC5. This is not good board layout practice but it made the track placing easier. The relays, the six 2-way connectors, the fuse clips and the power diodes (Dl-D4) are installed next. Be careful with the orientation of the diodes: A pin of RL9 fouls S3 , so bend the pin before you solder it. Ensure that the connector screw terminals face the centre of the board and check that the fuse clips are oriented correctly. Before installing 11 and 12, place about 10mm of spaghetti insulation over one lead and bend this lead back HEATSINK 7B05 .., ., --, 1 _ _ _ _ _ _ _ BEND DOWN _ _ _ _ _ PCB ~---+--+ Fig.5 : the heatsink for the BEND HOLES A= 3mm DIA. MATERIAL:· 1.6mm ALUMINIUM .1/.P_ fir---10 ::! 7805 regulator should be bent up according to the dimensions shown here . Make sure that the heatsink doesn't short against any other parts on the PC board when it is bolted in position (see above). 70 DIMENSIONS IN MILLIMETRES down the side of the choke. Mount each choke so that the covered lead is next to diodes D1-D4. The sockets for ICZ and IC4 can now be soldered in place, followed by R18, R19, R22, R23 & R26-R35 (most are end-mounted). The rest of the capacitors and D13-D15 can then be installed, together with the two crystals (Xl & XZ). Install Xl so that it sits slightly proud of the PC board. Similarly, mount CZ about 3mm proud of the board to provide clearance for the adjacent mounting nut. IC3 and IC8 are the next to go in, followed by transistors Q1-Q3. If you want, you can use a socket for IC3 (PCF8573). Take care with the orientation of the transistors. Now we come to the LEDs which are a bit tricky. The best approach is to cut two pieces of thin cardboard to use as temporary standoffs. Each piece should be 10mm wide x 100mm long and has to be thin enough to fit in between the legs of the LEDs. The eight red LEDs (LEDs 1-8) go in the top row and are each mounted with the cathode lead (ie, the longest leg) in the round hole. Position the piece of thin card along the line of LEDs, then install all eight LEDs over it and solder one side of each LED only. This done, remove the card and align the LEDs before soldering the remaining leads. It is easier if you do this from the solder side (remember the LEDs are mounted on the solder side). The green LEDs are mounted in similar fashion. R9,R17,R8 , R16,R7,R15,R24,R25 & VR1 can now all be installed on the solder side of the board. This done, turn the board over and mount R2-R6 and R10-R14 (end on). Before soldering the battery holder into place, check that one of its leads doesn't foul switch S3 on the other side of the board. Bend the lead so that it will be facing away from the switch if necessary. You may also have to cut off the small standoff that clashes with one end of R9. Place about 10mm of spaghetti over the leads of 10W resistor Rl before soldering it to the PC board. This method of mounting leaves it about 8mm above the board to allow for air circulation, as it gets quite hot (although it is well within specification). Mounting the display The 14-way LCD connector can now be mounted on the solder side of the board (use the short pins). This done, position the LCD over the long pins and secure the opposite edge of the display with 2mm bolts and 6mm nylon standoffs. An insulating washer must be installed under each nut on the silk screen side of the main board. Now adjust the height of the connector side so that the display is level and solder the pins. If you feel uneasy about permanently mounting the LCD in this way, you can install a row of Molex pins on the board and solder the short pins of the connector to the display board. That way, the display can be quickly removed to give access to the main board. The battery should be mounted in its holder with the positive side facing upwards. Be sure to mount to 10W resistor (Rl) about 8mm above the board so that the air can circulate beneath it for cooling. JULY 1992 37 All that has to be done now is to mount the front panel using the 3mm bolts and 12mm standoffs provided. Use plastic insulating washers under the nuts for the top two holes. The main body of the case comes without any holes in it for the solenoid and supply leads, so that you can choose the exit points. A series of small holes, the same diameter as the cable used , spaced evenly along the bottom of the case will probably be the most convenient. Switching on Before switching on, rotate VR1 fully anticlockwise and do a final visual check of your soldering. Don't plug the microprocessor in yet! Now turn on the This is the solder side of the PC board, with all the power. The red LEDs parts (including the LCD) mounted in position. should all light up and, Note that two of the resistors on this side of the after about one second, board go under the LCD (see Fig. 3). the green LEDs should light and the relays A fairly substantial heatsink must should operate. The 2-chip type LCD be fitted to IC1 (7805) to provide suffi- should have all pixels lit, while the cient heat dissipation. Make this heat- single-chip type should have the first sink up as shown in Fig.5 and bolt it eight character positions lit. Check loosRly to IC.1 and then to the PC the voltage at the output of the 7805 board via the hole provided. This regulator (IC1) to ensure it is 5V. If all the above happens, turn the done, solder the IC in place and tighten power off, plug in the microprocessor the mounting bolt. The PC board assembly can now be and re-apply power. This time, all the completed by installing the battery red LEDs should flash on (none, some or all may stay on) and the LCD should positive side up in its holder. Date Tin1e <-:•)1·1 , , ~ . ·,.,,. ' I ,\. l.c '" •• ·~ . c ~'dc D;iy • T Ti 111c say "SPRINKLER V 10" or "GRB V13", depending on the display used, for about a second. After that, the time and date should be displayed, except that there will be nonsense values showing. The colon between the hour and minute should be flashing. Adjust VR1 until you are happy with the contrast of the LCD. Now press S1 - the settings for sprinkler 1 should now appear on the display. They will all be nonsense values and question marks but that's normal at this stage. Press S1 until the time setting display is reached. The cursor should now be flashing over the HOUR setting which can now be adjusted by pressing S3 or S4. Once the hour is set, press S2 again to move to the minute setting. When the rest of the settings have been completed, press S1. This process writes to the clock and EEPROM and returns to the default display. The colon should be flashing and the values that you just entered should be displayed. If this happens, turn off the power, wait about five seconds, then switch on again. The time and date should be as you entered it. In particular, take note that the year is correct, as this is stored in the EEPROM and indicates that writing and reading is working properly. Press S1 again - the red LED for sprinkler 1 should now toggle each time S3 is pressed. Similarly, the green LED and the relay for sprinkler 1 should toggle if S4 is pressed. Initialising the EEPROM The next step is to initialise the to all zeros. This process is a bit tedious but it is good practice and only has to be done once. (Unfortu- EEPROM I)ate L ~u~ 'Ei'.11e: Stai t , Im . . ' - - - -- - Start Hour • • • ~ The default display shows the time (hours : minutes) & the date (day: month: year). Although not visible here, there is a flashing cursor between the hour & minute digits. 38 SILICON CHIP Pressing button S1 brings up the SPRINKLER SETTING mode. The desired station can then be selected for programming by repeatedly pressing of St. The LCD is secured to the main board via a 14way pin header at the top & two 6mm spacers at the bottom. The completed board assembly is then secured to the front panel on 12mm spacers. A cardboard template ensures that the LEDs are all mounted at the correct height (see text). nately, there is no room in the EPROM to include an initialising routine). First, select sprinkler 1, then press S2 to move the cursor to the CYCLE field. Pressing S3 or S4 will increment the cycle number, with the cycle values displayed in the fields to the right. When "1" is displayed in the CYCLE field, press S2 to move the cursor to the START HOUR and then press S3 or S4 until the display shows 00. Repeat this process for the ST ART MIN and RUN TIME fields . Return the cursor to the CYCLE position (by pressing S2) and repeat the above process for cycles 2, 3 and 4. The entire procedure should now · be repeated for the rest of sprinkler settings (ie, for sprinkler 2, sprinkler 3, sprinkler 4 and so on up to sprinkler 8). Final testing As a final check, we 'll set sprinkler 1 to operate on cycle 1. Note the current time and set the start time to five minutes before and the run time to 10 minutes. Don't forget to press S3 to toggle the red LED on, then press S1 until the default display is reached (note: the unit will default to the current time and date display if a button has not been pressed for one or two minutes). At the next interrupt (ie, within 60 seconds), the green LED should light and stay on until the "start time " + "run time" has elapsed. Now set the start time a few minutes ahead of the current time. When the start time is reached, the green LED should turn on. The other functions can also be tested to see if they work but if you've got this far, it's likely that everything is functioning properly. To test the watchdog circuit, switch the power off and on quickly. You might have to do this a few times but eventually the microprocessor will fail to reset properly. The colon will not be flashing when this happens. After a few seconds, the microprocessor should au.t omatically reset and go through the start up sequence. 12V operation Apparently, the Hardie Pope solenoids will operate on 12V DC, although this is not recommended. The environment is likely to very damp and electrolysis could become a problem, especially where the solenoid tail is joined to the cable that goes back to the controller. If you do want to operate the unit on 12V DC, delete Dl-D4, Cl and Rl, and run a link from L1 to the far end hole of Rl. Another link then has to be connected from LZ to the earth connection associated with the diode bridge. Make sure that you don't inadvertently connect the supply the wrong way around though. Finally, the case supplied is not waterproof. This means that the controller will have to be mounted in an additional waterproof box if the site chosen is not under cover. SC Ii me .,.,,. ·T - , \ < i' ··· j ! T · l{u11 l i mc ·--:--,t :1r 1 :\l :11. ~ -- -·-S,;t rt II( • • • • • • After the station has been selected, pressing button S2 moves the cursor to the cycle position. The number of cycles can then be incremented by pressing S3 or S4. Pressing button St again after station 8 (S8) has been selected brings up the TIME SETIING mode. The time & date are then set using buttons S2, S3 & S4. JULY 1992 39 SERVICEMAN'S LOG Ho\V do you get to blast a ghetto? For a change this month, I'm starting off down south. J. L., from across Bass Strait, has another of his unusual stories. And although interesting technically, it is also nearly as much about the customer as it is about the equipment. These pages usually tell stories of difficult repairs to complex colour television sets or video recorders. This story is about something quite different - a Sharp stereo radio cassette, one of the devices commonly known as a ghetto blaster. The model in question was a GF7600Z, fitted with a single cassette deck, a 5-band graphic equaliser and a 4-band radio tuner. It came to me in perfect working order, except that the cassette deck would not rewind a tape. It would play, record and fast forward, but would not rewind. Years ago, when I did a lot of audio cassette servicing, I bought a reel tension gauge, something I should also have for video decks but have not yet got around to buying. It took only a second to pop the FRACARR gauge into the machine and determine that there was less than 5gm/cm ofrewind torque. Play torque was tolerable at 30gm/cm and fast forward was marginal at 15gm/cm. But neither of these last two figures was optimum and I decided that the deck would perform much better if they could all be brought up to specs. Fortunately, in audio cassette decks, this usually involves no more than fitting a new drive belt or belts. Only once or twice have I ever found the takeup or rewind clutches to be the cause of this kind of fault. In this deck, there were two belts involved: the main drive belt linking the motor to the capstan flywheel and a secondary belt from the flywheel to the takeup drive. I had suitable belts in stock so the exercise became one of removing the mechanism, fitting two new belts and reassembling the whole outfit. I can only assume that the people at Sharp had set about making this unit DEL ... best television antenna performance for less cost. as difficult as possible to service. No less than nine screws secured the cabinet halves and, when they were removed, the back of the cabinet separated from the front by no more than 50mm. It was restrained from moving further by the speaker leads, which were so short that I couldn't get my hands inside to release them. I had to use a pair of long-nosed pliers to grab the plugs and ease them from their sockets. After that, it was a simple job to release the cassette mechanism by undoing two screws and separating two plug/socket assemblies. 0103 The troubles begin It was about here that my troubles really began, because there was no way of replacing the drive belts without completely dismantling the mechanism. The motor was mounted upside down to the usual way. It was outside the mechanism, with the drive pulley inside, behind a large mounting plate. This plate carried the main operation solenoid, as well as four microswitches operated by a cam on another plate lower down in the works. The only way I could replace the belts was to dismantle the whole mess, then reassemble it slowly and carefully. There was only one serious prob- Fig.1: the power supply circuit in the Sharp GF-7600Z ghetto blaster. Ripple filter Q103 functions as an emitter follower type voltage regulator. 2SCl684 TAR Ic.+-+-----~~~~----<>-+-__,;111,--, I SWIOt-A I -+-,l--+-+="'F--4---' ... I l~_...,:IWU-V)I 1 Fracarro 10BL4, 10BLS, 10BL45, 1Oelement yagrs that ~ work 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 ' ') I I I I l-o-SWS04 _ _. ' '~I :10001 I I _) 11:.IOC HL!CTOR wow! NIN£ S~L~S AN't> \M\?Oss,~R'-< .... 1"SN 3 S'fLO(Kf;'f - THeN 'Fl~SE~'!AA'\MSt & 6oooovot--r ~~OR:.:1" Sf'E~~R "S~t(E.MN-l'S 1'6~t>-S ! r,, ~- suR~L \~E." SR\,CH E.XPR.ot>l"1G wOOOP~ C.O~t\tOIIJ ~ 'PRUG, c Nv\ ~'fW, ~if'~INJ). 2 ,~ F~~e:: Df'X:>6'1 9 000 / • r o,., CA~ ONL.Y ASSUM~ -rHAi 11-t~ 'PlWPL..e: A-r S HA~P H~'t> SIS."\ ASoOi' MAKI ~ c;. 1'H \ S UN \1'" AS 7::>JFF'ICl/t..T A.'S 'POSSI St..~ -ro S~RVl Ce:..o..lem during the reassembly, as I was trying to refit the cabinet front. One of a row of four function switches along the front of the chassis failed to enter its proper recess in the front panel and the shaft was bent rather badly. It took several minutes to find out what had happened and to determine that no obvious damage had been done to the switch. In all, it was the sort of job that I always wish I had never started when I'm half way through, but then find quite satisfying when it's all back together and working properly. Except that this time, all was not working properly. Sure the mechanism now had a steady 40gm/cm on each function and could rewind a C90 in just a minute or so. But there was no output from the speakers, on either cassette or radio. I immediately thought of the switch that had been abused earlier. This had been the Tape/Radio switch which is effectively the main on/off switch, and a problem there could cause the symptom of no sound. I once again undid the nine fixing screws and exposed the works. I had to arrange extension leads for the speakers, since the short leads provided made it quite impossible to service the chassis when the case was opened. With the chassis laid bare, I soon found that there seemed to be a distinct likelihood that the switch had been damaged in some way. The area around the switch seemed to be very sensitive to pressure and occasionally produced a loud burst of sound for a fraction of a second when the switch was operated. The sound died quickly but when a cassette was playing, there remained a very faint trace of the music if the volume control was advanced to full on. I plugged in a set of headphones and was able to hear quite plainly that the music was seriously distorted. I tried to tune the radio but there was no sign of any program, on any of the four bands. Only the cassette could produce any kind of signal. The distortion made me wonder if the output chip might have suffered some kind of breakdown due to the presumably damaged power switch. But I had no circuit diagram and the boards were a complex m ess of conventional and surface mounted components. I wasn't game to interfere with that lot without a service manual. By this time, I had invested as much effort as I was prepared to put into a job that wasn't going to earn me a fortune. It would have to be put aside until I had had a chance to talk to the owner and find out how much he valued the unit. If he was prepared to pay a reasonable amount, I could afford to buy a manual and spend more time on the job. At that time, I gave no thought to what I would do if h e still wanted it fixed at the old price. As it turned out, the owner must have forgotten all about the radio, since it was still on the shelf four months later. I was reminded of the set when talking with a colleague about another Sharp product. So I asked him if he had a manual for the GF-7600X and, after a quick search, he. turned up the very thing. So I was back in business, whether or not the owner still wanted his set fixed! With the circuit diagram in front of me, and using an au dio probe, I was able to trace the signals through the audio preamplifier from the cassette input to the volume control. These all sounded more or less normal and I was at a loss to know wh ere the distortion I had heard in the phones was coming from. No radio signals However, the audio probe could find no trace of any signals from the radio board. It sounded "alive", but there was nothing that could be called a signal anywhere on any of the bands. One common cause of no response in a radio is failure of the local oscillator. This happens more often than you'd expect and is usually the result of an open circuit oscillator coil. An easy way to test for this fault is to tune the faulty set to a station around mid-scale on the broadcast band and then bring a small pocket radio close to the antenna rod. If the pocket radio is then tuned to the top end of the band, a spot should be found where its oscillator is 455kHz above the wanted station and leakage from the little set will push a signal JUL Y 1992 41 SERVICEMAN'S LOG - CTD through the faulty front end. In my case, however, the exercise seemed be pointless since the fault existed on the FM band, as well as on the medium and shortwave bands. It was too much to expect that both the AM and FM oscillator coils had failed at the same time. So, I had to look for a different cause of my troubles. And, in fact, it was not all that difficult to find. All the inputs and outputs for the RF board came together at a single plug assembly on one corner of this board. And each point was clearly labelled with both its function and the normal voltage on the circuit diagram. The first one I tried was the main supply rail (designated B+) which should have been around 10.SV. In fact, it was only 2.5V - easily low enough to explain the missing radio programs. Without the circuit diagram, I could never have found the cause of this loss of voltage. I traced the 10.SV line back from the RF board to the function switch mentioned earlier. From there , the rail found its way right across to the other end of the main board to transistor Q103. This transistor was wired in emitter follower.configuration and labelled "Ripple Filter". There was about 15V on the collector of this transistor but only 2.5V on the emitter. Sure enough, the transistor was open circuit between base and collector. However, there must also have been some leakage between ~ - emitter and collector, because there was some output from the filter. It · also explained the distortion I had heard from the cassette, because the same rail also supplied the drive stages of the audio amplifiers. The radio was mute because the low voltage killed the local oscillators, although the liveliness I had noticed was probably the result of a still active IF strip. A new transistor soon had the set back in working order but left me wondering about the reason for the sudden transistor failure. It had been perfect right up until the switch was abused but I can't see any connection with that event. The switch wasn't damaged and still works perfectly. It's just one of those puzzling things one sometimes finds in electronic servicing. Funny attitude When I had replaced those nine screws securing the cabinet, I put it back on the shelf and began to wonder if I would ever be rid of it. It had been four of five months since the owner had last put in an appearance and it looked as though I'd have to make a trip to a distant suburb to chase him up. Fortunately, I found his phone number and called to give him the good news. He didn't seem to be the least bit interested but still turned up a few days later, paid the bill without question, and wandered off with the monster under his arm. I got the feeling that he would not - ~ • - P~\ t) '0-\E:- 'gl L,.t.- VJ 1~0\M" /"41, ~£s•no1'l & w~t>&•t.o ~Ff W\1"M 42 SILICON CHIP ~e. N\ON'SrG UN't>Pt ~\S MMu, have worried if I'd never fixed it. So why did I fuss over it? I dunno. I guess I just like fixing things! Thanks J. L., but do you ever worry about the rest of the community who will have to live with the ghetto blaster? Perhaps fate had really intended that it should never be fixed and you have defied the will of the gods. Curses upon you! The pickle foundry And now, here's another one in lighter vein. As C. J. Dennis would have put it, "I know a bloke 'oo knows a bloke 'oo toils in that same pickle foundry." Only it's not a "pickle foundry" and he doesn't boil the "cabbitch storks". No, it's an electronics organisation, and the "bloke" would be better described as an electronics technician. All of which is a round about way of saying that this story came to me very much secondhand, so it's a little short on detail in places. But it goes something like this. The bloke who my bloke knows - hereinafter known simply as the bloke (leaving my bloke out of it) - keeps a plastic ruler handy alongside his video recorder. Why? Well, it's a rather complicated story. While this bloke works in the electronics field, he is not in the service game. Nevertheless, he's clued up enough to tackle service on most of his own equipment. And quite recently he acquired an Akai VS-112EA video recorder - a reasonably modern model with several interesting features. No, it didn't fall off the back of a truck; fell out a garbage can would be more like it. While the history of the machine is rather vague , it appears that it was discarded by its original owner because of its unreliable behaviour. And, after passing through several hands, it finished up on this bloke's workbench - it was his if he wanted it. Of course, by this time, the history of its behaviour had long since been lost. No one even knew what fault it was exhibiting. So he simply connected it to his TV set and gave it a burl. And it worked, in all modes. Too good to be true, surely? And it was. After about 30 minutes it shut down, and wouldn't start until it had been turned off and allowed to stand for some time. Well, it didn't take a genius to con- heated, it could no longer drive the elude that it was a temperature remotor. And when this stopped, senlated fault. We were spared the details of the tracking down but it turned sors in the machine shut everything down. out to be an IC that was overheating. So this bloke simply fashioned a And it was overheating because it had apparently been fitted with a heat- heatsink from a strip of brass. It was roughly "U" shaped, to push over the sink which was now missing. IC, and with a couple of wings to aid There is some suggestion that the dissipation. And it worked; the maheatsink was glued to the IC, since the latter was coated in some kind of chine would now run indefinitely glue-like mixture which was very with no sign of distress. Problem solved? Well, that one, yes. tough but not glass hard. Another suggestion was that this was a heatsink But now another one appeared; percompound which had been baked haps the one that caused the machine to be chucked out in the first place. At hard by the overheating IC. Anyway, the discovery seemed to times, the drum motor would not start, and it appeared to depend on the exmake sense. The IC, a type TA7245F, act position in which it stopped. All fed the drum drive motor and was mounted on a double sided printed it would do was shudder. So the bloke simply put his finger board which carried six flat coils, arranged in a circle, in close proximity on top of the drum and gave Ha spin. to the motor armature. This descrip- And away it went, running perfectly. tion, as it came to me, reminded me of Now this bloke appears to be a pretty a similar type of motor which I de- easy going type. If it was as easy as all scribed in these notes for December that, why worry further? Granted, the timer function could 1990, complete with photograph- the main difference being that that was a . not be relied upon, but the machine capstan motor whereas the bloke's was hadn't cost him anything anyway. a drum motor. And where does the plastic ruler And apparently, when the IC over- come in? Well, he got a bit sick of AUSTRALIAN MADE TV TEST EQUIPMENT 10% discount on all test equipment. 15% discount on two or more items. STES Built-in meter to check EHT transformers including split diode type, yokes and drive transformers. $78.00 + $4.00 p&p TETIA TV TIP JVC HR-7200 video recorder Symptom: no picture, just a number of horizontal lines with snow in between them. The sound seems to be normal. The machine was making a shrill whining sound when in play or record. Cure: the problem is the video head drum running very fast. This is caused by the loss of frequency generator pulses from the drum motor. There are a number of possible reasons for this problem but one unlikely cause was corrosion on connection pins 2/11 and 2/12 on the MDA (motor drive amplifier) board. TETIA TV Tip is supplied by the Tasmanian branch of the Electronic Technician's Institute ofAustralia. Contact Jim Lawler, 16 Adina St, Geilston Bay, 7015. pulling the cover off - even with the screws left out - every time the motor baulked. Then he realised that he ANTRIM TOROIDAL TR ORMERS C Built-in meter reads positive or negative voltages from 0-S0kV. For checking EHT and other HT voltages. $98.00 + $5.00 p&p ■ Strong magnetic field. Double insulated for your CAswitch operation. 240V safety with momentary AC 2.2 amps. As important as a soldering iron! $75.00 + $10.00 p&p r TER Designed to test infrared or ultrasonic control units. Supplied with extension infrared detector lead. Output is via a LED and piezo speaker. $84.00 + $4.00 p&p ~~~ - TUNER REPAIRS From $19 exchange plus post & pack Cheque, Money Order, Visa, Bankcard or Mastercard 216 Canterbury Rd, Revesby, NSW 2212, Australia. l".V. TUNER9 • ••~ ~w •·•W, • ~ Phone (02) 774 1154 Fax (02) 774 1154 • • • • Now made in Australia Standard range 1SVA to 2kVA Large ex-stock quantities available Competitive pricing available for OEMs & resellers • Simply the best transformers all round HARBUCH ELECT ON CS T D 90 George St, Hornsby, NSW 2077. Phone (02) ~76 5854 Fax (02) 476 3231 JULY 1992 43 ""<=OU\,t:) ~ 1"1"" WM'"~ ~ ~U~~ 6-IV6 l"'f" 11-let. ~A~ could see the top of the drum through the front loading aperture; and that he could reach it with the ruler and give it the necessary kick start. The theory advanced to explain all this was that a drive circuit in the IC for one of the coils had failed. This may have been because of the overheating problem or, as suggested earlier, as a natural failure which caused the machine to be discarded in the first place. And that is the story as it came to me. Unfortunately, I'm not very familiar with this model. In fact, I don't even have a manual for it and, while I have serviced a few, this was some time ago and did not involve this section. But I did manage to get access to some data and, significantly, it offered the advice that the motor should be replaced if it fails to start. My stock of scrubbers And there the matter rested for a while, as a curiosity story with a number of questions unanswered. But I did make a mental note to keep a lookout for this model should it come into the workshop. Then, more recently, I happened to be scrabbling through my stock of scrubbers - items written off as too costly to repair but kept for possible spares - when I suddenly spied an Akai VCR in one corner. And suddenly its history clicked. It had been a perfectly good machine, relatively new, until Jupiter hurled a thunderbolt into the area and wrecked it, along with several other appliances. Its owner hoped that I could repair it but it was not a proposition. Subsequently, it became the subject of an insurance claim and the 44 SILICON CHIP & Kl Ctc: St"'A~-T;,,,. owner then suggested that I might as well k1:1ep it; was of no use to him. More importantly, it turned out to be a VS-112EA; the very model in question. At the first opportunity I pulled the cover off and took a good look at the drum drive motor. In general terms, it fitted the previous description very closely. The rotor was a mild steel disc, about 18g and 45mm in diameter, and having a flange around its perimeter, about 5mm deep. And sitting snugly inside this flange was a ring-shaped permanent magnet. This rotor assembly was mechanically coupled directly to the drum, immediately above it. The stator consisted of the previously mentioned assembly of six coils, the driver IC, a smaller IC, and some minor components, all on a double sided PC board, and most of them surface mounted. The board was similar in width to the disc but about 70mm long. It was semi-circular at one end and rectangular at the other, this latter area accommodating the IC and various other parts. But there was one very significant difference between this board and the description as it had come to me; there was no heatsink on the IC. And, clearly, there had never been one, nor was there any need for one. I had "known" the machine since it was new and there had never been any suggestion of overheating problems of any kind. So what did it all mean? At this distance one can only speculate. The best suggestion I can come up with is that the whole thing started with a fault in the IC, long before the bloke came into the picture. This caused Top view of the drum motor stator board in the Akai VS-112EA video recorder, with the rotor (magnet) in approximately its normal position. In practice, it is suspended slightly above the board, below the video drum. This underside view of the stator board shows the surface mounted components & IC TA7245F in the top left corner. The motor drive coils are under the circular steel plate. the overheating and subsequent shutdown as already described and someone else decided to fit a heatsink, which they glued on. Only the heatsink wasn't big enough and/or the glue failed, and the experiment was written off as a failure. Then, later, it finished up on this bloke's bench and the rest we know. Anyway, I'm planning to send the motor board down the line via my bloke, so that this bloke can make a proper job of it. I reckon it is a fitting reward for a story like that. SC ORDER FORM BACK ISSUES* MONTH YEAR MONTH YEAR MONTH YEAR MONTH YEAR *Back issues are $AS each (incl. postage). Overseas orders add $A 1 per issue for postage. BINDERS Please send me _ _ SILICON CHIP binder(s) at $A14.95 each (incl. postage). Overseas orders please add $A3.00 each for postage. TOTAL PRICE $A SUBSCRIPTIONS r------------, □ New subscription - month to start I I I I I I I I I I □ Gift subscription~ □ Renewal - Sub. 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Please have your credit card details ready Fax the coupon with your credit card details 24 hours 7 days a week Card expiry date I Mail coupon to: Freepost 25 Silicon Chip Publications PO Box 139, Collaroy Beach 2097 No postage stamp required in Australia JULY 1992 53 Portable 12-volt SLA battery charger This simple project allows you to recharge 12V sealed lead acid batteries from your car. It uses only one low-cost IC and charges at a constant 13.BV. By DARREN YATES How many times have you needed to charge a sealed lead acid (SLA) battery while on the move from one place to another? This small project does just that. All you have to do is connect one set of leads from the charger to your car's battery and the other set to the SLA battery, and turn the charger on. What could be easier? If you wish; you can leave this battery charger permanently in circuit between the car's battery and the SLA battery, even when the latter has a load on it. That's because the output of the charger is kept at a constant 13.8V. In operation, the charger will supply over 300mA initially to the bat54 SILICON CHIP tery, with this current gradually decreasing as the battery voltage reaches 13.8V. This makes it suitable for use with SLA batteries with a rating of 1.2Ah or more. Circuit.theory The 12V SLA battery charger is a step-up voltage converter based on the MC34063A DC-DC controller IC. The major elements of the MC34063 are shown in Fig.1. This IC contains all the necessary circuitry to produce either a step-up, step-down or an inverting DC converter for any voltage from 3-40V. Its principal sections are a 1.25V reference, a comparator, an oscillator an RS flipflop and a Darling- ton transistor pair (Ql & Q2). The frequency of the oscillator is set by timing capacitor CT, connected between pin 3 and ground. A value of .00lµF gives a frequency somewhere between 24kHz and 42kHz but rarely is the exact frequency of the inverter important. As shown in Fig, 1, the oscillator drives the RS flipflop which in turn drives the Darlington transistor pair (Ql & Q2). Each time Ql & Q2 turn on, Ll is effectively placed across the supply voltage. These transistors stay on just long enough for the current through the inductor to build up to saturation, whereupon they both turn off. The energy in the inductor is then dumped into reservoir capacitor C0 via a diode. The Ipk sense line at pin 7 is used to monitor the peak current flow through the Rsc sense resistor. This is used to limit the peak current through the inductor to 0.3V /Rsc• The output voltage of the converter is set by two resistors which form a voltage divider across the output ea- 170 ~H Fig.I: this basic diagram of a step-up converter shows the major elements of the MC34063 controller IC. It uses an internal oscillator to drive an RS flipflop & this in turn drives a Darlington transistor pair which switches an external inductor. The IC also includes a comparator which compares a sample of the output voltage with an internal reference to derive a feedback signal. L r-------- --------, sl 180 ~4'_1_..,. I I I I I I I I I I 12 7I I I Rsc 0 .22 1N5819 I I 6I Vin 12 V roo I I I I I I icTJ 1.25 V Ref Reg I 1500 I I 5I pF 14 I .__ ______ - ------------..II R2 Vout - - ~ w . - - - - - - - - - - ~ - 0 2 e v n 1 5 mA R1 2.2 k •~ k pacitor. The formula is as follows: Vout = 1.25 x (1 + RZ/Rl) This voltage divider feeds the inverting input of the internal comparator, while the non-inverting input is connected to the internal 1.25V reference. The circuit relies on the comparator for voltage regulation. If the output of the circuit goes too high, the inverting input of the comparator will be higher than 1.25V and so the internal Darlington transistor will be off. Conversely, if the output goes too low, the inverting input of the comparator will be below 1.25V. The output of the comparator will thus be high and so the Darlington transistor can be toggled by the RS flipflop to switch current through the inductor. S1 F1 The result is a form of pulse width modulation which effectively reduces the amount of inductor current when only light loads are connected to the output and thus increases the efficiency dramatically. More importantly, it regulates the output voltage so that, under most loads, the output voltage remains as set. Circuit diagram Fig. 2 shows the complete circuit of the Portable 12V S1A Battery Charger. Power is supplied from the car battery, which is assumed to be about 13.8V. If this voltage swings around, it doesn't matter because the voltage regulation characteristic just described keeps the output of the charger at 13.8V. D.4W / 2A 5W •o--<:f'o--a---~-------, TO CAR BATTERY 18011 01 BY229 Q1 B0679 I.Cl MC34063 T0 12V SLA BATTERY C 8 22k 4.7k L1 : 60T, 0.633mm ENCU ON TOROIDAL CORE , NEOSID 17n32/22 2.2k PORTABLE 12V SLA BATTERY CHARGER Fig.2: the final circuit uses the MC34063 (ICl) to switch an external Darlington transistor (Ql) & this in turn switches inductor Ll. Each time Ql switches off, the energy stored in Ll is dumped into the 220µF capacitor via Dl. Zener diode ZDl protects the circuit against voltage spikes generated by the car's electrical system. It will also conduct heavily and blow the 2A fuse if the car's voltage rises above 15V. In addition, the 2A fuse provides protection against shorts in the output stage of the charger (eg, a short in Ql). The 0.4 70 5W resistor between pins 6 and 7 of IC1 sets the peak current through the inductor to about 650mA (ie, 0.3V/0.47Q = 650mA). Although Fig.2 works in the same manner as Fig.1, there is one important difference and that involves external transistor Ql. Unlike the circuit of Fig.1, Fig.2 uses the internal transistor pair to switch Darlington transistor Ql (BD679) and this then switches 11. This saves the IC from having to dissipate most of the heat and thus prevents possible damage. Each time Ql switches off, the collapsing magnetic field around the inductor tends to maintain the current flow in the same direction. This current is now diverted via Dl and charges the 220µF output capacitor. Ql then turns on again and the cycle repeats itself. The internal oscillator frequency is set by the .00lµF capacitor on pin 3 to somewhere above 24kHz, the exact figure varying somewhat for each IC. Because of this high switching frequency, a normal 1N400X rectifier diode is unsuitable for Dl - it would just get hot and eventually fail. The BY229 used instead is a fast recovery diode which is designed for switching currents at high frequency. The 220µF capacitor is used to store the energy from the inductor and also acts as a filter to smooth out the ringing waveform. Diode D2, a 1N4004, is necessary to increase the voltage difference between the input and output. If you look at the circuit, you will see that there is a direct low-resistance path from the input to the output; ie, via the switch, the 2A fuse, the 0.47Q resistor, inductor 11 , and diodes Dl and DZ. Because the circuit is a step-up converter, direct current would flow from the input to the output if the input voltage were to rise high enough to overcome the 1.2V drop across the diodes; ie, above 15V. Because car systems are regulated to 14.4V or less, this undesirable situation should JULY 1992 55 Fig.3: mount the parts on the PC board as shown in this wiring diagram. Take care when installing Qt & Dt. Qt is mounted with its metal face towards the 4. 7kQ resistor, while Dt is mounted with its metal tab towards the 220µF capacitor. PARTS LIST 1 PC board, code SC14107921, 60 x 45mm 1 plastic zippy case, 83 x 54 x 28mm 1 Dynamark front panel label, 78 x50mm 1 SPST toggle switch (S1) 1 toroid core, 14.8mm OD x 8mm ID x 6.35mm H (Altronics Cat.L-5110) 2 M205 fuse clips 1 2A M205 fuse 2 large alligator clips 1 cigarette lighter plug 1 metre of 0.63mm diameter enamelled copper wire 3 metres of heavy-duty figure-a red/black cable Semiconductors 1 MC34063A DC-DC controller (IC1) 1 BD679 NPN Darlington transistor {01) 1 BY229 fast recovery power diode (D1) 1 1N4004 diode (02) 1 15V 1W zener diode (ZD1) Capacitors 1 220µF 25VW electrolytic capacitor 1 .001 µF 63VW MKT polyester capacitor Resistors {0.25W, 1%) 1 22k0 1 1800 1 4.7k0 1 0.470 5W 1 2.2k0 The 13.8V output is set by the 22k0 and 2.2k0 voltage divider resistors. This provides the converter with negative feedback which regulates the voltage and stops the circuit from taking off. Construction of 0.63mm enamelled copper wire (ECW) wound on a small toroidal core. Begin with a 2-metre length of wire and thread it half-way through the centre of the toroid. Now, using one half of the wire, wind on 30 or so turns around the toroid until you have completed one layer. Make sure that you wind the turns as neatly as possible and keep them as close together as you can. The other half of the wire is then used to wind a second layer over the first. Both ends of the wire should exit from the same point on the toroid. Once the winding is completed, the leads can be trimmed and bent at right angles to fit the circuit board. Scrape away the enamel from the ends of leads before soldering them to the circuit board. The plastic case can now be drilled to accept the on/off switch (S1) and Because the circuit uses so few parts , we've managed to fit the whole project, including the inductor and fuse, inside the smallest available zippy box. It measures just 83 x 54 x 28mm. All the parts are mounted on a small PC board coded SC14107921. Fig.3 shows the parts layout. The parts can be installed in any order but take care with component orientation. In particular, note that D1 is mounted with its metal tab towards the adjacent 220µF output capacitor, while Q1 is mounted with its metal face towards the 4. 7k0 resistor (see also Fig.2). Push these parts down onto the board as far as they will comfortably go be-00-0 fore soldering their leads. Each M205 fuseclip has a retainer at one end and this should go to the outside position. If the fuseclips don't fit into the board, use a 1.2mm drill bit to enlarge y the hole. Make sure that the electrolytic capacitor goes in the right way around and don't forget the ~ -...- - 14107921 two wire links. Inductor 11 consists of60 turns Fig.4: this is the full size PC artwork. ff l never occur. However, if it does, ZDl and the 2A fuse provide added protection. Note that D2 does not have to be a fast recovery diode since it is not involved in switching fast waveforms. An ordinary 1N4004 is sufficient. r RESISTOR COLOUR CODES 0 0 0 0 0 No. 1 0 56 SILICON CHIP Value 4-Band Code (1%) 5-Band Code 1% 22kO 4.7kO 2.2kO 1800 0.47O5W red red orange brown yellow violet orange brown red red red brown brown grey brown brown not applicable red red black red brown yellow violet black red brown red red black brown brown brown grey black black brown not applicable PCB and SCHEMATIC CAD :-- --- - - . - ---- - ':::t ·= i! TV If AMPLIFIE I ,,_ •• ' : • L •''J ,...,., ~~ ~ !~ ! ,i: +---------------- ,__ __ _____ __________ .J C•WWfh-• This inside view shows how the board fits inside the case. Tie knots in the battery leads before they exit the case to prevent them from coming adrift. the two sets of battery leads. Once this has been done, feed the leads through the case, connect them to the PC board and complete the wiring to the switch. The PC board can then be pushed down into the case and the switch mounted in position. Fit the output leads with crocodile clips (or some other suitable connectors) to mate with the SLA battery. For in-car use, the input leads can be attached to a cigarette lighter plug. Testing To test the unit, you will need a 12V DC supply plus a multimeter. A car battery is suitable but don't use a 12V DC plugpack supply as its output voltage under no load will be about 17V DC [which is much too high). A 9V DC plugpack should be OK but check its output voltage first. Apply power and measure the output voltage. It should be around 13.8V, although this may vary by about 200m V or so. If you don't get the correct reading, switch off immedi- =ffliJJlll/Jllf =Ill/I#'===== PORTABLE 12V SLA BATTERY CHARGER CHARGE VOLTAGE: 13.8V EASY-PC • Runs on PC/XT/ AT/286/386 with Hercules, CGA, EGA or VGA. • Design Single sided, Double sided and Multilayer boards Connect the main battery leads to a cigarette lighter plug if you intend using the unit in your car. ately and check for incorrectly oriented parts ~nd for missed solder joints. If everything is OK, connect your multimeter in series with the SLA battery to be charged and re-apply power. Depending on the charge of the SLA battery, you should get a reading of about 300mA or less. The closer the SLA battery is to 13.8V, the smaller the charge current. SC Fig.5: this is the fullsize artwork for the front panel label. The holes for the screws that secure the lid to the case can be cut out using an artwork knife. • Provides Surface Mount support • Standard output includes Dot Matrix/Laser/Inkjet printers, Pen Plotters, Photo-plotters and NC Drill • Award winning EASY-PC is in use in over 12,000 installations in 70 Countries World-Wide • Superbly Easy to use • Not Copy Protected Options: • 1000 piece Schematic symbol library • Surface Mount symbol library • Gerber Import facility For fullJnfo 'phone, fax or write: BTC PO BOX432 GARBUTT 4814 QLD. PH (077) 21 5299 FAX (077) 21 5930 JULY1992 57 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. - - - - - - - -- -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - • 1 2 V 16 16 I RELAY 12V s11 IC1 4017 0.1 14 CLK 0.1J 1M 0.1+ .,. ..__ IC2 4017 .]L 14 CLK 1M IC3 4017 ..ll. 14 01! ,.. 2 CLK 1M -: -:- _ ._ _ _ _ _"""""'IRESET .......1.,..3..,.,.8... D1 1N4148 1M Sequential combination lock This is a rather unusual combination lock in that the buttons must be pressed the right number of times and in the right order. With the circuit shown here, the combination is 2, 3, 4 and 1. This means that you have to press button Sl twice , S2 three times, Modification to headlight controller One drawback of the headlights controller described in the January 1992 issue of SILICON CHIP is that there is no way to turn the lights off if it is dark and the engine is running. Driving into a drive-in is one examp le of 0 S3 four times, and S4 once. S5 resets the counters. You can change the combination simply by connecting the switches to the appropriate outputs. In essence, each button is used to clock a 4017 decade counter along to a specific output. When this output is clocked high, the following button can then be used to clock the next counter along to its designated out- put. If you make a mistake, you just push the reset button and start again. Each button has a O. lµF capacitor and 1MQ resistor to debounce the clock inputs. The RC network across the reset button also provides a poweron reset facility so that all three counter are reset at power on. when this feature would be required. Adding circuit Fig. l(a) is a cheap, easy solution. Thus , when switch S2 is closed, pin 9 of IC1 is pulled low via diode D12. If a flashing LED is used for LED 2, the circuit could then have the added function of a thief deterrent. Circuit Fig.1 (b) is a better solution and uses a 4013 flipflop and the unused gates of the existing 4584 (IC2e and IC2f) to provide a more "automated" control of this function. Under normal conditions, the Q output of the 4013 is low which pulls pin 12 of IC2 high and allows normal operation of the circuit. With the motor running (or the 30 second delay on), pressing S2 will cause the Q output to change state, thus turning the lights off. Pressing S2 a second time will toggle the flipflop again, allowing the lights to turn on. The reset pin of the 4013 is connected to pin 3 of IC2 which will reset the flipflop whenever the motor is turned off or the 30 second timer expires. Inverter IC2e provides a switch debounce circuit for S2. +8V .-------•8V IC2e 4584 11 -+-1...i---10 IC1, PIN 9 10 --~-.av " LED2 1.5k 10k (a) 05 BC548 (b) Fig.t(a) is the cheap & easy solution to turning the headlights off when the engine is running, while Fig.t(b) allows the lights to be toggled on and off by pressing S2. 58 SILICON CHIP Sheldon Munoz, Lidcombe, NSW. ($20) Gary Fowler, Rackham West, SA. ($20) +5V---------. 0.47+ 24 s Decimal To Common Cathode Displays 21 VPP vcc 0---------------------..aiAO 7 0 - - - - - - - - - - - - - - - - - - - - - - - = - 1 A1 g 7x330n 0011-'-.w,;,,---i A 011-"1O~Mr--18 · ~ - - - ' - - - - + - - < 1 - - - - - - - - - - - - 6 A2 5 ~--'>-------------------'-t A3 4 0 - - - - - + - + - - 4 - - - - - - - - - - - - - ' l A4 IC1 02'.l-'-11'---<\o\Mr--lC 13 0 D o - - - - - + - + - - 4 - 4 - - - - - - - - - - - - . a i 3 A5 2716 04 14 , u - - + - - - + - - + - - - - 1 - - + - - - - - - - - - - - - 2 A6 E r-:7s -- e/ /c -0- 0 15 1 u---t----+-+-----:1--+--r---+----<t------1A7 23 Su------+--+---+-....._---<___---->--+------- A8 A 16.-Mr--tG 061-- IO---t----+-+-----:1--+--i----+-+-----J-~2"'12 A9 _OE 20 A10 GN0 CE 19 12 18 10x10k .___._ ___....._...._____..___ _ _ _-....__ _____...___ _.___ ov .,. Fig.2: circuit for a decimal to 7-segment decoder using a 2716 EPROM. +5V Address Data 0 001 3F 1 002 2 004 06 SB 3 008 4F 4 010 66 5 020 6D 6 040 7D 7 080 07 8 100 7F 9 200 67 Decimal To Common Anode Displays 21 VPP 24 0.47+ BCD IN Ao--....- - - - - - - - BAO vcc 00 6 9 7x330n 01 10 A 8 02 11 B~-~-------- 7 A1 C IC1 2716 A2 0 13 04 14 f/e :{/c 0 15 5 A3 10k Decimal Address Data 0 001 co 1 002 F9 2 004 A4 3 008 BO 4 010 99 5 020 92 6 040 82 7 080 F8 8 100 80 9 200 98 -0- 16~Nr---lG 061" 10k Decimal A4 AS A6 A7 AB A9 A10 GND CE DE 4 3 2 1 23 22 19 12 18 20 ,____...__....______.._..1---111---111...-------ov Fig.3: circuit for a BCD to hexadecimal decoder. Both common anode & common cathode displays can be used (see table below). BCD To Hex 7-Segment Decoder Data (Common Anode) Data (Common Cathode) · 0 1 2 co 3F F9 3 4 BO 99 92 82 F8 06 58 4F BCD Address 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 5 5 7 A4 1010 1011 1100 1101 B 80 98 88 83 C D C6 A1 1110 1111 E F 86 8E 8 9 A 66 6D 7D 07 7F 67 77 7C 39 SE 79 71 BCD & decimal to 7-segment decoding with an EPROM While there are some BCD to 7-segment decoder ICs available, su ch as the CMOS 4511, there are no decimal to 7-segment decoders and nor is there a BCD to 7-segment decoder for displaying hexadecimal numbers (ie, 0-9, A-F).By storing the appropriate code in an EPROM such as the 2716, you can do any of these conversions to either common cathode or common anode displays. Fig.2 shows a circuit for decimal to 7segment decoding using a 2716 EPROM, while Fig.3 shows a BCD to hexadecimal decoder. The codes are listed in h exadecimal in the accompanying tables. (Editor's Note: most EPROMs can source and sink very little current so for a bright display, the EPROM outputs will need to be buffered). Nick Kounelis, Broadmeadows, Vic ($25) JULY 1992 59 Altronics - Now Even Greater Value & Efficiency 'With the recent installation of our new mail order computer, Altronics is now set to amaze you (our valued customer) with even faster and more efficient service. Just place your order on our Toll Free 008 999 007 line by 4.00pm E.S.T. and in most cases we can deliver to your door step the next working day (country areas 24-48 hours later).' Regards, Jack O'Donnell 40 Watt Inverter Kit 05 <EA Aug · > Digital High Performance Signal Generator Kit (SC July '90) Highly Accurate 4Digit Capacitance Me er Kit (SC May '90) This Digital Sine/ Square Wave Gen~r~tor uses high speed CMOS ICs and a d1g1tal filter IC to produce sine and square waves over the frequency range from 0.1 Hz to 500kHz. It also features a 4-digit frequency readout and an output level control. This inverter is ideally suited for powering low wattage mains appliances from a car battery. ldeai for camping, boating etc . Typically , it can be used to power an electric shaver, electric blanket . electric can opener or a 40W light bulb. Ou tput frequency can be either crystal locked at 50Hz or variable over a small range via internal trimpot. When 240V is available this inverter can be used to recharge car batter~.('. K Normally $pt,.OO K 2547 Normally$ ~.00 , ~W..E"'.tit~xr,; /. ,,/. ---· ;Jj" ~.c, < <,1 I I $125.oo The Discolite flashes party lights on and off in beat with music 4 light channels• Forward reverse and auto-reversing chaser patterns • Strobe function • Alternating light patterns • Music modulation available on chaser and strobe • Inbuilt microphone for beat triggering or audio modulation of lights • Front panel LEDs mimic light display • Altronics Kit pre-punched and silk screened. 6705 Now $9O.oo Video Enhancer Kit (EA Oct '83) Now 5805 Normally $~.50 Now$129.oo K n ectI Video Amplifier Kit,_ (EA Aug '88) For computers and videos with low video , -~ "" ,, ""·Yi'=«' ~~✓,xwm : ~' ,,~,%~ ill This video amp can greatly improve picture stability and eradicate shimmer, screen swim etc. Two outputs, normal and inverted. Ideal for VCR users. Tired of a grainy or snowy picture? Connect this amp internally to your TV and presto, the improvement is fantastic! (Docu mentation is quite detailed on connection to TV sets). Unit sharpens picture detail, and can actually improve the quality of a copy by amplifying the top end of the video signal output. Specifications. Signal to noise ratio 50db ref. 1V p-p • Fre~uency response (flat): 1Hz to 6.5MHz -3db • Boost and cut plus and minus 6.3db • Gain Odb • Input impedance 68 Ohms Complete kit supplied with silk screened front panel K (SC ec '89) Thll Dlgllal Recorder delivers aatonlshlng reproduction of voice and/or music ~ without any moving parts. Here is a digital voice recorder that can $,, ! ,1%~~ store 4 different signals, voice, sound or a music source of up to 30 seconds each or one recording of up to 2 minutes. Typical appllcatlonI Include: • Alarm system messages • Sales messages for customers put 'on hold ' • Experimental telephone answering machine • Door Station announcer. Talking displays fo r shops. Emergenc y warning message A~ ;;;;, , , 5850 Normally$ J.(:50 Now $ 15.oo Di~ital Voice Recorder Kit K Wr:,,. 9555 $149.oo ·"' ";, 5825 Normally $;,KC.50 Now $35 .00 -s--'-------c ---------1 creecher a r Alarm announcement • Operation instructor for machinery etc • Countless other (EA Aug '86) K This attractive 4-digit capacitance meter is designed for the workshop or laboratory. It can measure capacitance from 1pF up to 9999uF in seven ranges with an accuracy of better than +/-1%, +/1 digit. 2524 Normally $1)9.95 Now $99.oo FM Stereo Transmitter Kit (SC Oct '88) K Turn Your CD Player Into a Mini FM Tran1mltter. Simpl y· connect your CD player or any other source to the mini mitter which converts the audio signal to an FM signal. This FM signal then can be tuned in via any FM radio. Great for listening to your favourite CD while washing the car, mowing the lawn or doing the vacuuming etc, without blasting the neighbours. Powered by single 1.5V penlite battery. Single IC circuit. Simple to build and construct. 1120 Normal ly $~.50 Now $35.oo Fluoro Inverter Kit (SC Feb '91) K applications where voice or music is required • $100's cheaper than imported dig ital recorders• Includes instrument case and all components . Voice Operated Relay Kit Deafening lldb Modulated Tone Now our top selling Car Alarm Kit. Two Sensor inputs - Normally open and normally closed enable simple connection to door, bonnet, boot light, switches etc. Automatic Charger for NiCads Kit (EA July '89) " Here is a fully automatic NiCad battery charger that enables differing charge rates as appropriate for AAA, AA, C, D cells or cells in series up to 9V. Requires M 9020 12V AC PI ug Pack $16.95 atures: • Fu lly unched and reened case • ariable charge te • Variable mer • Flexible and s, isual display of charge mode • not be over charged. ( EA Apri I '82) This versatile Vox circuit is triggered whenever a noise or sound is made causing a relay to close. Think of the uoeo: • Controlling tape recorde,,s • Slide projectors • Eliminate the need for a press to talk button on transmitters • Turn on external porch lights • Paging systems • Hands free intercom switchover • Reaction sensitivity and "On Time" are fully variable 12V Gell Cell Charger Kit (SC July '89) This simple circuit will recharge your 12V Gell Ce lls correctly, increasing their life span. Charging current and voltage is controlled and over-charging is avoided b the IC switching off when the cell is fully charged. Features: • Automatic charge rate • Extends life of Gell Cells • 15V DC - 24V DC input• Simple to construct. This kit enables you to build a high power DC inverter suitable for driving fluorescent lights from a 12V source typically a car battery . Ideal for use in camping or boating. 6350 (16W Version) $35.95 6360 (20W/40W Version) $43.95 Solar Generator Kit K K iETI Dec '87) Charge Your Batteries Free From The Sun The Solar Generator charges and maintains your standard 12V lead acid car battery via the sun. (SC Jan '91) Fantastic for maintaining batteries which are not used or checked frequently. Ideal This charger is designed to operate from a 12V battery. it can charge nicad battery for boats, caravans and remote data packs from 6-12V at up to 6A, or you custom wire the circuit to charge battery acquisition stations etc. Note: Must be packs up to 30V at a reduced current used in conjunction with a suitable solar In operation the circuit will recharge a typical nicad racing pack in about 20 minutes. panel. Features: • Fast charge rate• Switch selectable voltage setting in 1.2V steps from K Normally 6V-12V • Fully punched and screened front panel • State of the art digital circuitry. 1685 Normally $?250 Now $2O.oo High Capacity ast Charger for Nicad Batteries Kit K K 1660 Normally $1;,tf.oo Now $99.oo ;;;..______...,....,.---4 1680 $µ{s $1 O.oo Now Stereo 50 + SOW Midi-Style Amplifier Kit (SC Feb and March '92) Rap/ace That Old Beaten Up Amp' This fantastic new amp has all the features of commercial units costing hundreds of dollars more using tip 142/147 transistors it is capable of producing, a total producing a total of 50 Watts per channel RMS. Into 8 Ohms makes an ideal replacement midi unit. Performance: Output Power: 55W into 8 Ohms 80 watts 4 Ohms l::~~o;J~ dl1tortlon: typically K 5045 $299 .oo 0 120 SOW Mosfet Module Kit 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 HiFi or buy two and make your own stereo amplifier. Beat Triggered Strobe Kit (AEM July '85) Add Some Life To Your Next Party Designed by Australian Electronics Monthly. Flashes in time to your music. Will a!so work as normal strobe. Exclusively customised by Altronics into our H 0480 Instrument Case, making construction a breeze and improving stability and overall appearance. Includes silk screened panel. Two tube option available which boosts lighting output. K 5790 Normally $~95 Now $69.oo att Public Address Amplifier Kit High Performance Low Nolte P.A. Amplifier This professional quality Public Address Amplifier offers performance equal to better than commercial units, at about half (SC Nov '88) ud/, . .,.,.,,, W mi.»~~ in everyday situations where numerous speakers and long output ,uN ,,_ ,_,, ~ " . the price. Amplifiers using 100V line outputs are used extensively ll ' ' .' lines are employed. Ideal ly suited for Halls, Churches, Clubs and S even temporary setups. i:: $150 00 Input•: 2 balanced mics (3 Pin XLR connectors), 2 Auxilliaries (RCA connectors) MASS/Vi;; · 0utputa: 4 Ohm, 8 Ohm or 100V line. Power Output: 125W RMS into 4 Ohms, 90W RMS into 8 Ohms, 120W RM S into 100V line Frequency Responae: 30Hz to 30kHz $ $349 Harmonic Distortion: Less than 0.3% from 20Hz to 20kHz K 5020 Normally ~-00 Now .00 K5115$49.s5 Low Cost 'Karaoke'- Adaptor Playmaster Pro Series One 200W Mosfet Module Kit (EA Dec '89) (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 i'' This amplifier module ha~ tt"-1:! same high specs as the "S1..,, ;.;u Pro Series One", but in short form Le.: One mono module - no power supply or case. Fantastic for use in Juke boxes, amplifier racks (multi-amplifier setups) t~ • -u 1 ·~-' ...J KAR.AOK6 sox ,\7"""""- Single 'DI' Box K"t rEA oc; '87) it •.,!.,.. -/ ;}-- .. . J l ~.11 --,_ (■ u -1 microphone. It's a great wa y to liven . up a party! This project Converts high impedance unbalanced works on the assumption that the lead vocal in most stereo recordings has been placed mid-way between the left and right channels, or is in fact a mono signal. Requires 2 x 9V batteries. discos etc. See above for inputs to low impedance balanced outputs. Used in studios, music, PA industry to convert high impedance Simply connects In line between CD or Tape Deck and Amp. Mlc Socket 6.5mm Jack. specifications. devices i.e .. electric guitar pickups, synthesizer etc. K 1170 Normally $~.00 K 1170 Normally $,;34"95 Now $3O .oo K 5550 $45 .oo Now$79.oo New High-Tech Remote Ca I Flush/Surface Mount Alarm Panel "'°' '~ w;;" '""~ eom~c. ,o;,.,.,m smoothly into any residentialoo~ or office decor'""'' by either flush mounting into the wa ll , 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 whilsl still 1 ~ ........-1■ protecting entries. simple 4 digit access code for operation. See Altronics '92 catalogue for full details . s 5490 $ 1),ef.oo This Month $99.oo Satellite This UPS (Uninterruptable This amazing new model features just about everything you could imagine! Multifunction keyring remote control will arm and disarm alarm (and activate central locking if fitted) , chirp the horn, turn on car headlights, panic and even open the boot (if actuator fitted) . One remote can control two alarms. Other features include: Starter inhibit , valet mode, cer,,tral locking interface, flashes car indicators when tripped, auto reset plus much more! !249 Power Supply) will supply 12 V ~~b~~t~~~!;i~~~ ~~ti~rnal This self contained compact unit can deliver a massive 120d8. lt connects via 3 wires to any alarm system that has an battery even when th e mains has failed . Ideal for use with alarm system power supplies monitoring systems, warning systems etc . S 5230 .00 ._s_5_2_3_1.;.,_e_p_1a_c_e_m_e_n_t_R_e_m_o_te_c_o_n_t,_0_1_$_4_8_._so________________, M 9090 output that is normally negative. Will sound if the wires are cut. Arm/disarm inbuilt key switch . $69 _95 S 5235 $6~5 Intro Price $55.95 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 tarn per circuits. The S 5240 system includes main co n troller, 1 Passive Infra Red Movement Detector, 1 wi ndow 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 whole system is codP.t so it can not be interfered with and can be changed any time by tne owner. Each individual sensor can be easily set to operate en any sector. The main contrc :1e, ,tilizes latest EEPROM technolog~· which means things like selecting user on/ off codes, isolating sectors are a breeze. Includes a mynad of other amaziQg ..t.e.atures, too. man Call AL TRON/CS today for a free colour brouchure. Complete 1y1tem tncludH: 1 ; : ~~;;i~o~ Red Detector/Transmitter 1 x Door/ Window reed Switch/Transmitter 1 x Hand Held remote Control/ Transmitter 1 x Horn Speaker - 10 watt/wired 1 x 240V AC adaptor 1 x 1.2Ah Back-up Battery r:i~: External Siren C 2015 $1 Now 1 x Set of batteries for all transmitter~ Door/Window Reed Switch & Transmitter S 5247 $7~ Now $63.95 $11 mention. .Wireless Rt>mote Keypad S 5255 $1.,16"."00 Now $114.95 A 2210 .,._4(~,.}~•-' -.._ :·r---~-_ -·11 ~:Jfu~ - _ Normally $~.00 This Month $199.oo Thi• fanta1tlc tuner 11 the Ideal add-on to any 10und 1y1tem. Can be uaed a1 background mu1lc 10urce In reataurant1, 1hop1 etc or any PA application. Al10 a great upgrade for the home HI-FI. Featurea: • 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• Phaselock loop (PLL) IC for FM multiplex stage • Dimension s: (W x H x D) 435 x 60 x 232mm • Weight: 3kgs. A 2040 $ ~ This Month $539.oo Thl1 stereo amp 11 Ideal for background/foreground appllcatlon1. Fantaatlc for re1taurant1, 1hop1, dl1co'1, aerobic,, PA 10und 1y1tem1 and home. • 90 watts RMS per channel • 2 large power meter indicators • XLR socket for speaker terminal • Output relay to eliminate turn-on and off transients 100mm Super Carbon Polyswitches Fibre Speakers These devices provide These amazing little speakers will impress you and your friends . Carbon Fibre is a new high tech material from which these speaker cones are made. Complimented with Barrium ferrite magnets the results are simply amazing. 8 and 16 ohm versions available makes multi speaker installations a breeze. Weatherproof design makes them ideal for car doors and boats! 0 C 0641 8 Ohm 50 ' C 0643 16 Ohm UP sav• ,o Normally $~95 This Month $25.oo or $40.oo pr 2 ' Guitar Speaker 50 Watt1 RMS, 100 Watt1 Max. Attention all guitarists and keyboard excellent protection for your speaker sy stem . They simply connect in series between your amp and speaker. When the current exceeds the polyswitch rating they go open circuit, thus protecting your expensive investment. R 4050 For Tweeters up to 100 watts 0.5 amp at 50V $6.20 ea R 4055 For Midrange/Woofers .up to 100 watts 1.15 amp at 50V $6.95 ea R 4060 For Complete system up to 200 watts 2.45 amp at 50V $8.90 ea ,. P 8110 $289.oo Save your precious and expensive computer hardware and hi-fi etc f~om t~e power surges, spikes and lighting . A must for anyone who doesn't want their equipment blown up! New 8 way model contains two power filters. Quality Replacement Speakers sAVE ovER 30% 165mm 3 watt. 4 & 8 Ohm taps C 0620 were$~ This month $5.95 musicians This fine 150 x 100mm USA designed speaker is supplied as standard equipment to the world famous brand name series of Guitar Amps. • Impedance: 8 Ohm • Sensitivity: 101dB/W (0.5m) • Weight: 2400gm 3 watt,4 & 8 Ohm taps C 0622 were $~5 This month $6.95 178 x 125mm 3 watt, 4 & 8 Ohm taps c 0624 were $1)'50 Specifications: Frequency Range: 10Hz - 1MHz Accuracy: +/-3% + 2Hz Output Waveforma: Sine/Square Output Level: Sine: BV rms · Square: 10V P-P Output Attentuator -20dB, -40dB and fine adjust ,,.,,,/_ a 1540 Normally $,7"''-'·oo Now$250.oo $8.so Normally $99.oo Stereo Extension Ceiling $79 -T-hi_s_Mo_n_th_o_n_1y_ _._oo_ _ _ _ _ Speaker Kit Want a set of high grade extension speakers for onal Dome the back patio, games room, den, workshop, C 3102 kitchen? Well here at Altron ics we have put Ferro Fluid cooled voice coil 60 watts power capability. Silky smooth frequency response 1.SkHz to 20kHz. Wide angle dispersion. In comparative tests we rate this fantastic new Dome Tweeter superior to the VIFA D19! (which costs $45 or more) . Incredible low price. together this great kit which includes speakers, grilles, cable, screws and even a wall mounted vo lume contro ller. The speakers are our high quality 4" C 0626 dual cone drivers, with stylish wh ite grilles ideal for mounting in the ceiling. Volume control mounts in standard electrical wall box and includes 6 volume settings as well as off . Includes 2 x 20m cable. C 3016 Normally $)<at>".50 C 0988 Normall y $ ~.00 Now $30.oo. This Month Only $69.oo Components Bargain Pa ks Ca--,b ,-o_n....,R'"e - 1""1,-tor Pack Average Contents: 300 R 3501 Normally $6.95 Now $6.oo ¼ M tal nm Re lstor Pack Average Contents: 150 R 3505 Normally $5.95 Now $5.oo Gr encap Capac acks Average Contents : SO value. R 3510 Normally $5.95 Now $5.oo C . m c.a acltor Packs erage Contents: 100 Now 5.oo .'i'F.:~'H~i'=:ltor ack rage Contents: 40 a 1550 Normally $~00 Now$225.oo This month r ¼ With provision for both internal and external modulation. Specifications: Frequency Range: 100kHz - 150MHz in 6 ranges RF Output Level: 100mV rms Accuracy: +/ -3% Modulation: • Internal (30% depth): 1kHz • External: 50Hz-20.kHz • Crystal Locked Oscillator Winner of the Taiwan Good Dealgn· Award Now you can solder anywhere with this new gas soldering iron. Feafurea • 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 1200°C • Can be easily refilled with standard butane lighter gas• Replacement tips are less than half price of some other brands! • T 2451 Replacement T 2452 Replacement T 2453 Replacement T 2454 Replacement • ALL $4.95 ea 1mm Conical Tip 2mm Conical Tip 3mm Conical Tip 3mm Chisel Tip IT 2455 Replacement Exhaust Port T 2456 Hot Knife Tip T 2458 Blow Torch Tip T 2457 Hot Blower Tip $10.95 T 2448 Weller Butane Gas Refill $6.95 cIlloscope A superb oscilloscope for technicians and engineers working on projects where other instruments wou ld be stretched beyond their capabilities. Where precise measurements of computers, CD's, digital videos, RF applications, high speed digital, and other high speed equipment is a must. With Features Like: • Delayed sweep for partial waveform expansion • Channel 1 signal output for use with a frequency counter • CH2 polarity inversion switch • Vertical deflection magnification, X5 • Switchable chopping frequency • Scale il lum inating system• B Intensity control for bright, magnified waveforms • Variable hold-off for observation of waveforms with complex periods • Single sweep mode for one time or other suddenly occuring events • Sweep magnification. X 10 • Signal delay line for accurate view of high frequency pulse leading edge• Trigger preset function. With the introduction of our new range of rack cases, we have sacrificed the old stock at below cost! This means fantastic savings for yo u - our val ued cu stomer. Please note stocks are limited - no back orders. - All $25 - All $30 - All $35 H 0404 Grey c~•'. . ,;- H 0405 Grey HS0402 Silver Anodised Top quality blank panel clearout. All stock must go at these crazy prices. Stock is limited with definately no back orders at these prices. 2 unit - All $8.00 H 0422 Natural Aluminium H 0432 Grey H 0435 Black 3 unit - All $12.95 H 0423 Natural Aluminium H 0433 Grey 1 HS0403 Silver Anodised H 0413 Black Powdercoat H 0406 Grey ' g anufactured ar R ck Frames ~ - I -/ ·oudly Made Australia H H H H H H H H H H H H 5204 5205 5206 5207 5212 5213 5218 5219 5230 5231 5238 5239 Now $125 $44 $135 $49 $152 $80 $170 $99 $205 $143 $242 $175 Rack frame 4U Nat. Panel set for H 5204 Rack frame SU Nat. Panel set for H 5206 Rack frame 12U Nat. Panel set for H 5212 Rack frame 18U Nat. Panel set for H 5218 Rack frame 30U Nat. Panel set for H 5230 Rack frame 38U Nat. Panel set for H 5238 H H H H H H H H H H H H 5304 5305 5306 5307 5312 5313 5318 5319 5330 5331 5338 5339 H 5352 2 Unit (88mm) Normally $ ~ 5 Now $39.95 Rack frame 4U Black Panel set for H 5304 Rack frame SU Black Panel set for H 5306 Rack frame 12U Black Panel set for H 5312 Rack frame 18U Black Panel set for H 5318 Rack frame 30U Black Panel set for H 5330 Rack frame 38U Black Panel set for H 5338 Now $125 $44 $135 $49 $152 $80 $170 $99 $205 $143 $242 $175 tl g .·... ·.·.',,..;...· .. <>·. .. ..,..... ·. ·./ ·\,. X 2125 Normally $ ~.00 ~€,\.. THIS MONTH ONLY $69,oo H 5354 4 Unit (176m m) Normally $~95 Now $45.95 Save On Discounted Tools Top quality palm grip series with spring return makes these tools a breeze to use and a must for every tool box. T 2710 Flat Nose Pliers T 2720 Needle Nose Pliers T 2730 Curved Needle Nose Pliers All were . 5-'i\ -:.Jr,,o I 4~ ---?. t Yet another Altronics innovat ion, proudly designed and made in Australia. These great new speaker mount brackets simply screw onto the wall and speaker allowing a universa l 50° ang le of adIustment. Suitable for speakers up to 5kg. No special tools required. Available in white or black. A must for any extension speaker. H 8010 White H 8012 Black $39.95 pair "------------... • Designed to house amplifiers , inverters, power supplies, micro-processor equipment, etc • Mounting posts provided for PCB's, transformers• Vented for efficient air-flow cooling • Extra tough, super finish front and rear panels. H 0490 Grey Case, H 0491 Black Case, H 0492 Blue Case Normally H 5353 3 Unit (132mm) Normally $~95 Now $39.95 $¥s ea This month $6.95 ea • Black print and red print for subtractions • Sub-total/ total • Item counting • Average fun.c tion • 3 digit comma .markers• Full decimal ~ .- .,, system. Operates on 4 x AA . batteries (Included) or power supply. Includes one roll of 58mm paper and dust cover. I Enables rack ~ \ mounting of tuners, -~ videos, G.D. players, amplifiers etc . which normally can 't be rack mounted. Supplied in flat pack form - easily assembled in minutes. Available in black only. Suitable for home or commercial use , these fantastic rack frames are durable strong, good looking , light weight and easy to assemble . Th e frames are available in either Natural Anodised aluminium or Black Powder Coat aluminium and the side panels in Electric Blue or Black Powder Coat finish. Ideal for use in home Hi-fi systems, Professional Audio installations, Band Gigs, Computer Patch panel etc. Frames: Natural Anodised or Black Powder Coat Panels: Electric Blue or Black Powder Coat. ac~ Shelve~ or $18.oo set ol 3 Digital & Analogue Combination Multimeter This fantastic meter gives you the accuracy of a digital as well as the ease of an analogue! Features true RMS AC test. AC and DC current test, AC and DC voltage resistance continuity etc and many other features you would only expect on much more expensive meters a 1090 Normally $1~50 This month only $129.oo 5 Now $29.95 174 Roe St. Perth W.A. 6000 Phone (09) 328 1599 F .E 008 999 007 Cl- P.O. Box 8350 Stirling Street PERTH W.A. 6849 STANDARD DELIVERY & PACKING CHARGE $3 .50 to 500gms, $5.50 500gms -1Kg , $8 1 Kg-5Kg AUSTRALIA WIDE - We process your order the day rec eived 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 v1a Overnight Jetaervlce Courier for delivery next day Country areas please allow add1t1onal 24-48 hours HEAVY HEAVY SERVICE-All orders of 10Kgsor more must travel Express Road- Please allow 7 days for delivery. $12 .00 to 10Kgs. $15.00 over 10Kgs. INSURANCE - As with vi rtuall y 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 val ue (mi nimum charge $1) . When phone ordering please request " Insurance". TOLL FREE PHONE ORDER -- Bankcard, Visa, Mastercard Holders can phone O'der toll free up to 6pm Eastern Standard Time. Remember with our OvernlghtJetservlce we deliver next day. AL TRON ICS RESELLERS Chances are there is an Altronic Reseller right near you - check th is list or phone us for details of the nearest dealer. Blue Ribbon Dealers are highlighted with a ■ These dealers generally carry a comp rehensi ve range of Altronic products and kits or will order afly required item for you. COUNTRY ALBANY BP Electronics ■ (098) 412681 Micro Electronics (098) 412077 BUNBURY Micro Electronics (097) 216222 ESPERANCE Esperance Communications (090) 713344 KALGOORLIE Todays Electronics ■ (090) 215212 MANDURAH Lance Rock Retravision (09) 535 1246 PORT HEDLAND Ivan Tomek Electronics (091) 732531 ROCKINGHAM TV Joe's (09) 5271806 ALICE SPRINGS Farmer Electronics (089) 522388 DARWIN Ventronics (089) 853 622 VIC All Electronic Components (03) 6623506, TECS (03) 6706474 BORONIA Ray Cross Electronics ■ (03) 7622422 CHELTENHAM Talking Electronics (03) 5842386 COLLINGWOOD Truscott Electronics (03) 4198208 CROYDON Truscott Electronics ■ (03) 7233860 FOOTSCRAY G.B. Telespares (03) 3179100 PRESTON Preston EIGctronics ■ (03) 4840191 COUNTRY BAIRNSDALE LH & LM Crawford (051 ) 525677 BALLARAT Ballarat Electronics (053) 311947 CRANBOURNE Mart's Electronics (059) 968200 MILDURA McWilliam Electronics (050) 236410 OLD Delsound PL ■ (07) 8396155 WEST END B.A.S. 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"•"ro"'~ ,~, ~... Build this telephone off-hook timer How many times have you tried to have that afternoon snooze or that romantic dinner for two only to be interrupted by the telephone? This circuit takes the phone off the hook for you and then automatically replaces it after a preset time period. Block diagram Power for the circuit is derived directly from the incoming phone lines via on/off switch Sla and bridge rectifier D1-D4. This bridge rectifier ensures that the correct supply polarity is applied to the circuit, regardless of the polarity of the phone lines. When power is first applied, IC1 (the timer circuit) begins counting. About 5 seconds after this, it turns on the "Start-Up" SCR (SCR1) and this closes the line to simulate the phone being taken off hook. When IC1 reaches its preset time period, the timer latches and its output goes high and turns on SCR2. SCR1 an d SCR2 form a standard commutating circuit. When SCR2 is turned on, it steals current from SCR1 via capacitor Cl . This immediately turns SCR1 off, w hich places the phone back on-hook. SCR2 then turns off again a short time later since the current through R2 is insufficient to maintain conduction. The block diagram of Fig.1 shows how the circuit works in principle. Circuit details By DARREN YATES Phone calls in the middle of the night or right in the middle of dinner are annoying, particularly if they're the "sorry... wrong number" types. Most people use the age old solution to this well-known problem; they simply take the phone off the hook. The problem here though is that it is equally simple to forget to put the phone back on the hook. It can be quite a few hours later before you realise that it's been off. The Telephone Offhook Timer can save you from missing those important calls. By turning the circuit on, it automatically takes the phone off the hook for either 30 minutes, one hour or two hours, and then replaces it back "on the hook" again. The project is based on one common CMOS IC and a couple of silicon controlled rectifiers or SCRs, and fits neatly into the smallest zippy box. It's quite possible that you will already have most of the components lying in your junkbox. The Oflhook Timer has three preset time periods: 30 minutes, 1 hour & 2 hours. It automatically puts the phone back on hook at the end of the timing period. 64 SILICON CHIP Refer now to Fig.2 which shows all the circuit details. It's a bit more complicated than our block diagram but all the basic elements are easily recognised. At the heart of the circuit is IC1 which is a 14-stage ripple-carry binary counter. This IC carries a built-in oscillator circuit which is set to operate at approximately 1.3Hz by the RC components on pins 9, 10 & 11. Switch Slb selects between the Q12, Q13 and Q14 outputs of ICl, corresponding to the 30-minute, 1-hour and 2-hour time periods r_yspectively. Thus, when power is first applied, IC1 begins counting up. WhenQ4goes high, the pulse is .fed to the gate of SCR1 and triggers it on. This takes the phone off-hook and also lights LED 1 which is the off-hook indicator. ZD2 is there to ensure a constant supply voltage of 4.3V across the LED and its associated 220Q current limit- Fig.1: block diagram of the Oflhook Timer. Shortly after switch on, SCR1 turns on (to take the phone off hook) & timer IC1 starts counting. At the end of the timing period, SCR2 turns on & turns SCR1 off to place the phone back on hook. SCR2 then turns off again a short time later. 0-0 PHONE LINE START UP SCR1 TIMER IC1 voltage rail for ICl. Normally, with the phone off hook, this rail will be about 3.5V. Construction All the parts except for the switch and LED are mounted on a small PC board coded SC12106921 (61 x 42mm). Fig.3 shows the parts layout on the board. The parts can be installed in virtually any order but it's best to mount the smaller components first. Leave the SCRs and electrolytic capacitors till last and make sure that you don't confuse the two zener diodes. We suggest that you check each resistor with your multimeter before mounting it on the board, so that you can be sure of its value (see Table 1 for TURN OFF SCR2 OSCILLATOR HOLD 01 ing resistor of when SCR 1 turns on. When the selected output from IC1 (either Q12, Q13 or Q14) subsequently goes high, SCRZ turns on and turns SCR1 off as described previously. At the same time, transistor Ql turns on and pulls pin 10 ofICl low to stop the oscillator and latch the counter at its present count. When SCR1 turns off, the phone is effectively placed back on-hook but that's not where the circuit operation ends. What happens now is that the 2.ZµF bipolar capacitor (Cl on Fig.I) quickly charges via ZD2 in parallel with LED 1 and its 220n current limiting resistor. As soon as the capacitor charges, SCRZ turns off because its associated 330kQ resistor is too high to allow sufficient "holding" current. Fig.2: the final circuit uses transistor Ql to stop the counter when the preset count is reached. The counter is then reset simply by turning the power off & on again. Note that the minimum timing period can be decreased for testing purposes to less than 3 minutes by connecting a 330kQ resistor across the 3.3MQ timing resistor. LED 1 also turns off during this time to indicate that the phone is back on hook. The circuit is reset by simply switching it off (using Sla). Supply rails WARNING! When the phone is taken off hook, the line voltage drops from a nominal 50VDC to about 6.5V DC due to the resulting 35mA current loop. This value is about the same as the loop current that flows when a telephone is physically taken off hook. The supply rail for the SCRs is derived directly from the output of the bridge rectifier and thus varies depending on whether SCR1 is on or off. This rail is also decoupled using a 10kQ resistor and 22µF capacitor and applied to ZD1 to derive a more stable In order to comply with the Telecommunications Act, we draw the reader's attention to the following: "This customer equipment has no AUSTEL permit and may be dangerous or damage a telecommunications network. Connection to a telecommunications network is an offence under section 253 of the Telecommunications Act 1991 and may attract a maximum fine of $12,000". 2~ 1 a PHONE ft . . . LINE ~ OFF 330k + 22 35VW! 2.2 BP 16 Q4 7 """""'; ELJc VIEWED FROM BELOW A 10k 0.1 IC1 4060 KAG B 33k 014 3.3M 013 3 2 012 1 RESET 12 ,.. .,.B Slb TELEPHONE OFFHOOK TIMER JULY 1992 65 Fig.3: install the parts on the PC board as shown in this wiring diagram. Be careful not to confuse zener diodes ZD1 &ZD2. Take care with the wiring to the switch, as it's easy to make a mistake here. The SCRs are installed with their metal faces towards the 2.2µF bipolar capacitor. the colour codes). Take care with the orientation of all polarised components. The two SCRs must be mounted with their metal faces towards the centre of the board. Push them down onto the board as far as they will comfortably go before soldering their leads. Once the board has been completed, connect the switch and the LED using hookup wire. Be sure to connect the LED the right way around - the anode TELEPHONE OFFHOOK TIMER Fig.4: this is the full-size pattern for the PC board. OFFHOOK 0 OFF-~ - 30 MINS 1 HR - 2HR - Fig.5: this artwork can be used as a drilling template for the front panel. lead is the longer of the two (see Fig.2 for pin connections). The adhesive label can now be attached to the lid of the case and used as a drilling template for the front panel holes. These include a mounting hole for the LED plus two smaller RESISTOR COLOUR CODES 0 0 0 0 No. Value 4-Band Code (1%) 5-Band Code (1%) 1 1 4.7MQ 3.3MQ 330kQ 33kQ 22kQ 10kQ 2200 yellow violet green brown orange orange green brown orange orange yellow brown orange orange orange brown red red orange brown brown black orange brown red red brown brown yellow violet black yellow brown orange orange black yellow brown orange orange black orange brown orange orange black red brown red red black red brown brown black black red brown red red black black brown 0 66 0 2 0 0 2 1 SILICON CHIP holes to accept the switch mounting screws. The square cutout for the switch slider can be made by drilling a series of small holes inside the marked rectangle and then filing the job to a smooth finish. A small hole must also be drilled in one end of the box to admit the telephone cable. Tie a knot in the cable so that it cannot be pulled back through the hole, then terminate the two leads to the indicated points on the PC board. The other end of the cable is connected to pins 2 & 6 of a standard telephone plug. Operation Now that you've finished the construction, you can plug it in parallel with one of your existing phones via an adaptor socket. Now flick the switch to the 30 minute setting. Nothing will happen immediately. That is normal but after five seconds, when Q4's output goes high, the LED will come on. At the same time, you may hear a click from your phone. The phone is now "off hook" and no incoming calls will be received. If you now pick up the receiver, you should hear the engaged signal, confirming that the phone is indeed off hook. You will also notice that the LED dims when you lift the receiver. This is quite normal and it will continue to time out correctly when you replace the receiver. If you turn the unit on to the "2-hr" range, and then later decide you wanted only one hour's delay, you can switch the unit back to the "1-hr" setting provided you do so before one hour has passed since first switching it on. Similarly, if you first select the "1-hr" range and then decide on only 30 minutes, you must do it before 30 minutes has passed. Note also that if you turn the unit off and back on again quickly, you may not get the correct time you selected. If you wish to reset the timer, turn it off for at least five seconds and then switch it on to the desired range. Troubleshooting If it doesn't work, the first step is to check the wiring and the parts placement. In particular, check the wiring to switch Sl. If these checks reveal nothing, connect the unit to a 12-lSV DC power supply in series with a 5600 resistor, switch on and check that the output You can now afford a sate II ite TV system PARTS LIST 1 PC board, code SC12106921, 61 x 42mm 1 plastic jiffy box, 83 x 54 x 28mm 1 telephone plug and cable 1 double pole 4-position slide switch 1 5mm red LED 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: Semiconductors 1 4060 14-stage binary counter (IC1) 1 BC547 PNP transistor (01) 2 C106D SCRs (SCR1 ,SCR2) 1 5.1 V 1W zener diode (ZD1) 1 4.3V 1W zener diode (ZD2) 4 1N4004 silicon diodes (D1 -D4) *antenna, A 1.8-metre prime focus dish complete with all the Capacitors 1 22µF 35VW PC electrolytic 1 2.2µF 16VW bipolar electrolytic 1 0.1µF 63VW MKT polyester *or better). One super low-noise LNB (1.4dB *magnetic One Ku-band feedhorn and a signal polariser. Resistors (0.25W, 1%) 1 4. ?MQ 2 22kQ 1 3.3MQ 2 10kQ 1 330kQ 1 2200 1 33kQ * 30 Miscellaneous Insulated hookup wire, screws, solder etc Your receiver is pre-programmed to the popular AUSSAT transponders via the internal EEPROM memory. This unit is also suitable for C-band applications. of the bridge rectifier is about 5V. If you get 0V, check the diodes in the bridge rectifier and the wiring to Sla. Assuming tbat all is OK, plug the unit into the phone line and check that pin 16 ofICl is at about 4.5V with the LED off and about 3.5V with it on. If pin 16 is close to 0V but the output of the bridge rectifier is OK, check ZDl for incorrect orientation. If the supply rails are correct, LED 1 should turn on about 5 seconds after power is applied. If the LED fails to light, check the voltage across SCRl (ie, between anode and cathode). If the voltage is close to 0V, check the polarity of ZDZ and the LED. If the voltage is above 30V, check SCRl and its gate circuit components. Finally, if the circuit fails to switch off at the end of the preset period, check the wiring to Sl and the circuit around SCR2. You can speed up the circuit operation for checking by connecting a 330kQ resistor across the 3.3MQ timing resistor. SC $995.00 Here's what you get: mounting hardware. metres of low-loss coaxial cable with a single pair control line. *receiver lnfrared remote control satellite with selectable IF audio & bandwidth, polarity & digital readout. Call, fax or write to: AV-COMM PTY LTD PO BOX 386, NORTHBRIDGE NSW2063. 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 & 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 ACN002174478 01 /92 JULY 1992 67 NOKIA CONSUMER ELECTRONICS m ■ cron ■ c• PHILIPS 3IVI Arca Australian AMP BKC International CKE Comspec Fox Electronics General Electric Harris Harwin lgnis Intel lntersil Johnson Components Kautt & Bux KG Kitagawa Ind. Kriesler Litton MNCOM Maida Marantz Motorola National Electronics NEC Panasonic Parker Magnetics Philips Pulse Engineering Pye Rank Arena RCA RCD Components Redpoint Samsung Semikron Semtech SFE Technologies SGS-Thomson Sharp Siemens Sony Star Printers UTC Transformers Vitelec Warth SONY: ADELAIDE ROLEC DISTRIBUTORS (S.A.) PTY..LTD. 5-9 Rundloe Street, Kent Town SA 5067. Ph: (08) 366 0000. Faxstream: (08) 362 9900. ALCORA ELECTRONICS 94 Chandos Street, St. Leonards NSW 2065. Ph: (02) 906 1253. Faxstream: (02) 906 1263. Whirlpool ROLEC DISTRIBUTORS NEWCASTLE 1 Vista Parade, Belmont NSW 2280. Ph: (049) 47 0008. Faxstream: (049) 47 7018. ROLEC DISTRIBUTORS HORNSBY Unit 2; 107 Hunter Street, Hornsby NSW 2077. Ph: (02) 482 1944. Faxstream : (02) 482 1309. ROLEC DISTRIBUTORS AUSTRALIA PTV. LTD. 20 Hilly Street, Mortlake NSW 2223. Ph: (02) 743 3144 . Faxstream: (02) 736 3732. Telex: AA20186 . COMPUTER BITS BY PAUL LYNCH Good books on the PC can be well worthwhile It's possible that today's secondary schools are teaching their pupils properly about computers, and particularly about PCs, but I doubt it. They would be better off reading a few decent books. While researching a story on computers in schools some 18 months ago, I spent a melancholy morning in one of Sydney's "show installations" and watched hapless, eager, interested children pecking their way across their keyboards, rather like laboratory animals not quite sure which button would produce the desired grain of seed. My own children have attended five schools between them and at none have they found a computer club. At one school - one of the most famous schools in the state - my son told me that there would be no computer instruction at all in the first year but thern might just be an hour a week in the second. While there are secondary schools offering good computer courses, I gather that these tend to be places lucky enough to have one or two truly enthusiastic and largely self-taught computer-loving teachers. This may be bad news for Australia but it's good news for the publishers of self-help books about how the PC works. And it's good news for us PC users that some of these books are very good, indeed. I review two of the best ones this month. I know quite a number of PC users who spend $30 a month and more on magazines, because they know no other way to find out what's actually going on inside their computers. While computer textbooks and refer70 SILICON CHIP ences are generally expensive (the two volumes I review here each cost $59.95), they're a cheaper way than the magazine route for us all to learn about our PCs. The documentation supplied with most computers doesn't help all that much. Two of the better reference books are Peter Norton's Inside the IBM PC and PS/2 and The PC Users Guide by Nick Anis and Craig Menefee. Peter Norton's guide Peter Norton is one of the legends of the PC era. Some six or seven years ago, based on his reputation as a man who knew the innards of PCs, he was writing a regular column in a US magazine. In particular, I remember one in which he explained that you could make a buck out of selling commercial software from your home or ga- rage. His article included an explanation of how to buy cheap floppy discs, how to get cheap labels printed, and how to put the software on using the MS-DOS diskcopy command. ' I think he established that you could hope to mail your software out at a cost of something like $US1.50 a disc using all these cheap tricks. Presumably, these costs have not changed much but if you wanted to buy all Peter Norton's software today, you'd be spending the thick end of $A1000. For this, you would get your money's worth and more, because Peter Norton has proved one of the most brilliant of all those shirt-sleeved programmers of the early eighties at working out where the holes were in MS-DOS, and how the Intel processors and other hardware bits operate under DOS. Yes, this is the Peter Norton of Norton Utilities. His book, as you might expect, is a reasoned step-bystep guide to how computers do the things they do. In US textbook style, it also concludes each chapter with a list of possible projects. But his new book (the review copy is the fourth edition of a standard text and was published late in 1991) is not just a textbook. It's a true reference volume. One of its ornaments is an appendix called a "narrative glossary", which in 12 pages takes you through a coherent, interlocked account of virtually everything you need to know about in your PC. The technical words and phrases are printed in bold letters, thus: When a computer uses a common data path - a special set of circuit wires - to pass data from one part to another, this path is called a bus. The narrative then goes on to name various buses. DVORAK~~1• regard his book highly and recommend it for your computer desk. The PC User's Guide NickAnis& Craig Menefee Wh at if you want to know more about what a bus is? The index refers you t o a section in the main body of the book which describes them in detail. A famous programmer, Norton has written a special BASIC program for readers of the book, so they can write their own simple computer game. His section on programming is, of course, excellent but so is his information on hardware. The book's title is a trifle misleading. While it is indeed about the IBM PC and the PS/2, it's also about the PC clones and compatibles that most ofus buy and use. It's up-to- Nick Anis and Craig Menefee have written their reference book from a different perspective. It's 722 pages long, in comparison with Norton 's 398, and evidently the authors believe you should buy it before you decide on your next computer, or else should pick it up after you've handed over payment for your PC. There are sections on which type of machine to buy and on how to put your system together. There's a chatty, friendly style of writing that many will find encouraging (one example: "When IBM jumped into the personal computer market in 1981, it was like the arrival of Shamu the whale in the backyard inflatable swimming pool") . Unlike Norton, Anis and Menefee offer a valuable 40-page troubleshooting guide. While this does not cover every possible trouble that you might want to shoot one day, it does warn you bluntly about the risks of the more dangerous DOS commands, and it explains many of the hardware and software problems that arise. The authors also prudently tell you the difference between troubleshoot- "The PC User's Guide is equipped with an excellent index that makes it easy to use as a reference. It also offers extra treasures whose values may become more apparent to you as your expertise grows" STOCK SALE!! FANS 80 x 80 x 25mm 240VAC ..... $15.00 120 x 120 x 38mm 240VAC . $15.00 MISCELLANEOUS EA freq uency counter (1 only) .. ...... .... ............ ... ......... $200 Mains power lead with plug 10A ... ... ... ... .... ...... ... $4.00 Mains power plug .. ... .... .... ..... . $2.00 Cable ties 94 x 2.4mm ....... ..... ........ .......... ... . $4.00 per 100 FM stereo transmitter ..... ...... $49.95 Ceramic resonator 3.58MHz .. $1.00 ALKALINE BATTERIES AA size ........ ...... .... ... ... .. $1 .40 each C size .. ...... ...... ...... .. .. ... . $2.25 each 9U PP3 size ...... ... ... ..... . $4.30 each D size .. .... ...... ...... ..... .... . $3.00 each SEMICONDUCTORS 1N4004 ..... .......... .... ............ ... $0.05 1N4007 .. .... .... .... .... ... .. .... .. .. ... $0.08 1N4148 ..... ....... ... ..... ... .... ....... $0.04 MJ15003 ...... ... .. .. ... ....... ........ . $6.50 MJ15004 ... .... ........... ... .... ... .... $6.50 date in the sense that it discusses the i486 processor and the characteristics of laptops and portables, although (with one exception) Norton offers little brand-specific information. He firmly believes that IBM's ideas for the PC are the best in a number of respects. His section on IBM's Micro Channel Architecture explains MCA clearly and gives · the best argument I've read for going the high-priced IBM route. But it also gives the best argument for not going the same route, which is that the peripherals you have working with your clone's ISA and EISA boards won't work on an MCA mach ine. He expects, he writes, that the n on-IBM manufacturers will start to produce MCA machines one day but I have my doubts about whether this is right. In every other way, I ing (working out what's wrong, and fixing it) and service (handing.the job over to a trained specialist). The "PC User's Guide" is equipped with an excellent index that makes it easy to use as a reference. It also offers extra treasures whose values may become more apparent to you as your expertise grows. One appendix is a table of hard disc drive geometries and, from this, I learned that the disc in my 386DX was configured by the dealer to hold six fewer megabytes than its capacity. The book tells me elsewhere how I can get them back. I must get around to that some day, real soon. PS: in May 1992, I referred to an advertised computer with a 486 40MHz CPU. This was a mistake: the computer had a 386 40MHz chip. SC MJ15024 .. ..... .... .. ..... ... .. ...... ... $8.60 MJ15025 .......... .. ...... .. ... .. .. ... .. $8.60 TOA 1023 ....... ..... .. ... .. .. ........... $4.30 T DA1085 .. .. ..... ... ..... ...... .. ..... $18.00 TC9142 ... ... .. ... .. ...... ....... ...... .. $5.50 MC14514 ...... .... ... ... ..... ...... .... $3.00 NE555 ... ... ...... ...... .. ........ .... .... $0.40 MJE13007 .... ... .... .... ... ... ....... .. $4.00 ALL ITEMS 10 PLUS 10% OFF _HYCAL ELECTRONICS Unit 4, 62 Gt. Western Hwy, Parramatta, NSW 2150. Phone (02) 633 5477 Fax (02) 891 5640 Credit Cards Welcome JULY 1992 71 AMATEUR RADIO BY GARRY CRATT, VK2YBX Radiation hazards in amateur radio -:-- some simple precautions Concerned about the possible adverse health effects of long-term exposure to RF energy? If you operate amateur radio equipment, there are a few simple precautions that you should follow. Electromagnetic radiation is part of every day life. For the most part, such background radiation is of little or no consequence to the general public. In fact, energy resulting from RF radiation is deliberately used, under closely controlled conditions, by members of the medical profession to treat a variety of ailments. The heating effect of exposure to RF on human tissue is often used by physiotherapists to great During World War II, considerable concern was expressed over the number of radar operators suffering internal burns and cataracts. Such radar installations ran high levels of power and safety precautions were inferior by today's standards. Exposure to power densities of 1 OrnWI cm 2 was considered safe but today some scientists believe that exposure to levels of just 1mW/cm2 can cause tern- "Without conclusive evidence regarding minimum safe exposure levels, it is certainly good advice to keep as far away as possible from strong electromagnetic fields." advantage and the effects under such conditions are well documented. Most households operate a microwave oven, most have electric blankets, and most have TV and VDU screens. The use of electric razors and hairdryers is almost universal, so that some exposure to electromagnetic fields is unavoidable. Amateur radio operators, and particularly those working in the electronic industry, also face frequent exposure to a variety of other types of electromagnetic radiation and should be aware of the possible hazards such exposure presents. 72 SILICON CHIP porary ailments such as minor headaches. The research studies necessary to determine such "safety" levels can last for many years but, even after such lengthy periods, can be inconclusive, as the test subjects are normally animals which may be affected in different ways to humans. Nevertheless, it is prudent to exercise caution when periods of exposure are lengthy. Without conclusive evidence regarding minimum safe exposure levels, it is certainly good advice to keep as far away as possible from strong electromagnetic fields, including fields at low frequencies. Identifying such fields may be difficult without suitable instrumentation but there are certain commonsense guidelines which do apply. It is considered unwise to operate a hand-held UHF (in particular) transceiver over a long period of time in close proximity to the face . A far more sensible approach is to use a speaker microphone, allowing the operator to place the transceiver some distance away. As the intensity of an electromagnetic field is inversely proportional to the distance squared, removing the source of radiation by a relatively small amount lowers the field intensity dramatically. Hand-held cellular phones may pose a similar hazard, although the field intensity is much lower than from a typical amateur transceiver due to the lower output power level (typically 400mW). A study in the US some years ago identified the use of 5W 800MHz hand-held transceivers as a definite hazard. Similarly, it is hazardous to stand in front of a high-gain antenna, such as a multi-element Yagi, while it is operational. The EIRP (effective isotropic radiated power) of such antennas can reach levels of several kilowatts. Phased arrays of multi-element Yagis pose a very significant hazard. Hence, antenna testing should be approached with caution. Also, the human body absorbs more energy at lower frequencies than at higher frequencies and safety standards reflect this. Hence, there may exist more significant hazards when operating high powered HF equipment, compared to the relatively lower that strong sources of electromagnetic radiation are located away from the operating area. Antennas and transmitters should be located away from the area where most time is spent, and high voltage power supplies should be located on the other side of the room rather than under the operating desk. Linear amplifiers, particularly those capable of operating at high power levels, should always be operated with the RF shielding intact. Minimum standards powered VHF and UHF amateur equipment in general use today. It therefore makes good sense not to stand close to an HF transmitting antenna when it is in use. No doubt, those working in the broadcast industry are particularly aware of this point. Mains fields Numerous studies have been made to determine if there is any link between exposure to 50Hz (mains) electromagnetic fields and various medical ailments, such as leukaemia and cancerous tumours. Although none has proven conclusively that such a link exists, many have shown a higher incidence of such problems in groups of people having the same vocation. According to the IEEE journal "Spectrum", twelve US studies to date have all shown that an increased risk of leukaemia exists when workers are exposed to high field intensities of 60Hz. electromagnetic radiation for long periods. Due to the use of 240V domestic power distribution in Australia, Australians would appear to be at less risk than those in countries with 1 lOV power distribution. The average field intensities are lower in a 240V system due to the lower currents involved. Although it can be argued that such problems are as yet unproven, it would seem that action based on "prudent avoidance" is the safest solution. This may mean rearranging the "shack" so There are standards set in Australia which specifically spell out the maximum safe exposure to RF and lowfrequency magnetic fields. Australian Standard AS-2772, Part 1 & 2, precisely sets out the limits applying to handheld transceivers and other RF sources, and the methods used to measure these limits. These specifications are based on very carefully controlled scientific research carried out by a number of organisations within Australia. Finally, the National Health and Medical Research Council, based in Canberra, has produced a paper entitled "Interim Guidelines On Limits of Exposure to 50/60Hz Electric & Magnetic Fields (1989)". It details safe field intensity levels for low-frequency electromagnetic radiation. Both parts of this paper are recommended reading for amateurs wishing to familiarise themselves with radiation hazards. Further reading (1). "IEEE Spectrum", August 1990. (2). "Practical Wireless", May 1990. (3). "Reference Data for Radio Engineers" - published by Howard Sams. (4). "Australian Standard AS 2772". Parts 1 & 2. (5). "Interim Guidelines On Limits of Exposure to 50/60Hz Electric & Magnetic Fields (1989)" - produced by the National Health & Medical Research Council, Canberra. Further information is also available from the NSW Environmental Protection Authority, Radiation Control, PO Box 136, Regents Park, 2143, or contact the environmental protection agency in your state SC MASSIVE TEST EQUIPMENT SALE The following equipment is surplus to requirements and is now offered for sale. Most prices are negotiable. SIEMENS LEVEL TRACER K2202 digital storage, new $500.00 HEWLETT PACKARD HP 8064A realtime audio spectrum analyser. 50Hz-1 0kHz. As new condition $2000.00. AWA TEST OSCILLATOR G250-2 10Hz-61 0kHz $200.00 RACAL DANA 9008 automatic modulation meter, 1GHz, as new $600.00 HEWLETT PACKARD HP 141 T spectrum analyser (8554B + 8552B) $5700.00 ** HEWLETT PACKARD 1640B serial data analyser, new $1800.00 HEWLETT PACKARD HP432A power meter with cable & HP47BA thermistor mount power head $750.00 AWA MTS-A220 audio test set 100Hz-650kHz, nicads incl $250.00 Other items available, too many to list. See our advert on page 34 of the June 1992 issue of SILICON CHIP. We also buy used equipment, even if not operational. Turn your surplus equipment into cash. Please call write or fax: AV-COMM PTY LTD PO BOX 225 BALGOWLAH 2093 Tel: (02) 949 7417 Fax: (02) 949 7095 **Delivery within 30 days of order JULY 1992 73 2CH COS-5000 SERIES Each channel has a maximum sensitivity of 1mV/DIV. The Auto Trigger Level Lock uses a special pk-pk detector Vertical Trigger Mode to trigger asynchronous signals Vertical Hold-Off ensures easy viewing of complex signals CH1 signal output can be connected to other instruments. • Display CH1, CH2, Ch1+/-CH2, X-Y • Sweep Modes: Auto, Normal & Single Shot • Trigger Coupling: AC, DC, HF-REJ, TV • Trigger Source: CH1, CH2, Line, EXT &Vert Mode 2 SWITCHABLE PROBES INCLUDED. 20MHz OSCILLOSCOPE WITH DELAY 100235. COS-5021TM ~I~ I~l}.il] I~~~:~~j~~AN $1014.50 • Sensitivity 5mV/DIV-5V/DIV, DC to 20MHz • ATimebase 20ns/DIV-0. 5s/DIV (Main) • BTimebase 0.2us/DIV-0. 5ms/DIV (Delayed) 40MHz OSCILLOSCOPE WITH DELAY 100230. COS-5041TM $1299.50 • Sensitivity 5mV/DIV-5V/DIV, DC to 40MHz • ATimebase 20ns/DIV-0. 5s/DIV (Main) • BTimebase 0.2us/DIV-0. 5ms/DIV(Delayed) 20MHz OSCILLOSCOPE 100240. COS-5020TM CTIC550A ECONOMICAL BENCH~OPINSTRUMENTS $199.00 F300550 550MHz FREQUENCY COUNTER • 2CH Input, auto selection. • Dual Decimal Points Indication • 0.1 Second Gate Time CTI C89A $95.00 F300089 FUNCTION GENERATOR • 2Hz-200KHz (5 Ranges) • Sine, Triangle, Square Wave • 1%Typical at 1KHz CTI C86A $144.00 $144.00 F300086 UNIVERSAL COUNTER • 10Hz-60MHz Two Ranges • 0-9999999 Counts • 25mV RMS Sensitivity Escort CTI C87A F300087 AUTORANGING CAPACITANCE METER • 10 Ranges, fully Automatic with Range Hold. • Full Scale Value From 99.9pF to 99.9mF. • Accuracy 0.5% +/-0.5pF +/-1 Digit. 3 3/4 DIGIT DMM EDM-82 3013ao $161.50 • 3¾ Digit, BIG LCD Display • 12 Functions DC V, AC V, DC A, AC A and Ohm Frequency counier 1Hz to 4MHz (auto) Capacitance 4nF (1 pF) to 4O1-LF Diode foreard voltage test Transistor hFE test Audib le continu ity Logic level test Peak Hold $869.00 • Sensitivity 5mV/DIV-5V/DIV, DC to 20MHz • Timebase 20ns/DIV-0. 5s/DIV V DC V AC A DC A AC Ohm AUTORANGING DMM 301501 EDM-70H $53.90 3.5 Digit Pocket Size DMM 301502 EDM-72B $73.50 4OOmV to 1OOOV, 5 ranges 1OO1-LV max reso lution, ± 0.5% 3.5 Digit DMM w/Cap 301350 EDN!-162 $92.50 4OOmV to 75OV, 5 ranges 1OO1-LV max resolution, ± 1.2% 3.5 Digit, 7Funo~Autorange 301410 EDM-1133 $112.50 4mA to 2OA, 4 ranges Bar Graph, 8Func. Autorange 1f.LA max resolution , ± 1 % 301420 EDM-1155 $154.50 4mA to 20A, 4 ranges Bar Graph, 12Func. Autorange 1f.LA max resolution, ± 1.5% 4OOohm to 4OMohm, 6 ranges 301430 EDM-1177 $212.50 0.1ohm max resolution, ± 1 % Bar Graph, 14Func. Autorange VARIABLE TRANSFORMERS SINGLE PHASE, TABLE-TOP The HSN-Series are compact, table-top variable transformers. Input is 240V AC via a standard 3 pin plug. The output terminals are 4mm captive head type and a separate earth connector is provided. A large voltage control dial and a clearly marked scale are used to select and indicate the output voltage. The transformers are housed in a steel case, finished in grey enamel. MODEL OUTPUT VOLTAGE,Us OUTPUT CURRENT, Is WEIGHT(kg) HSN 0303/240 HSN 0203/240 HSN 0103/ 240 0-270V 0-270V 0-250V 0-13A 0-7A 0-5A 15.5 9.0 6.4 HSN-0103 283110 HSN-0203 283112 HSN-0303 283114 $220.00 $253.00 $385.00 ELECTRONIC KITS & MODULES A-ONE FUN, LEARN & SAVE $$$$$ ASSEMBLED & TESTED KITS AMPLIFIERS POWER SUPPLIES K100503 K110355 K111810 K120355 K200086 K200087 K210025 K210080 K210089 K100010 K100025 K100120 K100666 K100800 Kt00802 K102800 K110377 K110820 K111000 K200015 K200038 K200040 K201003 K210006 K210101 K218080 K212250 K221002 Stereo PreAmplifier with Magnatic Mic.Amplifier ....................................................... $20.00 Speaker Protector Stereo .... ............................................... $22 00 35W PURECLASS AMain Power Amplifier Mono ...................... ............... $64.00 Dynamic Noise Reduction System ............................................ . $39.00 120W+120W DC LOW TIM Pre-Amp & Power Amp .. ........................ $119.00 80W+80W Pure DC Stereo Power Amp ................ $109.00 NF-CRBI-FET Pre-Amplifier (with 3 way tone control) .. ... $72.00 State OfThe Art Full Complimentary Symmetry FET Stereo Pre-Amplifier.. ............... $159.00 60W+60WOCL DC Pre-Main &Stereo Amplifier ....... $99.00 100W Dynamic Class A Main Power Amplifier Mono . . ........ .. . $79.00 Stereo Tone Control Amplifier ....... .. ...... $15.00 Complete Speaker Protector Stereo .. .............. ................... $19.00 100WPURE CLASS A, Fully Symmetrical Power Amplifier Mono . ....... ..... $79.00 250W (BTL 320W) All FET, Dual Differential, Symmetrical Stereo DC Final Amplifier ..... .$199.00 40W x 2 IC Low Voltage Amplifier... . ................................................. ........ $33.00 BTL 200W or 60W+60W Stereo, Super LOW TIM Power Amp. with Speaker Protector ... $87.00 120W MOSFET Super Low TIM Power Amplifier Mono ..... ............ $69.00 Stereo All FET Pre-Amplifier with 5 Band SEA Equalifier ................ ........ $94.00 All FET, BTL 200W, Stereo 80W+80W Fully Symmetrical Super Low TIM Power Amplifier ........ .................................................... $t24.00 K230039 SOW RMS. 8 ohm PURE CLASS APower Amplifier Mono .......................................... $69.00 0-SOV 3A High Precision Power Supply with Short Circuit Break & Overload Protector .. $42.00 0-15V SA Regulated DC Power Supply . $37.00 0-25V 10A Professional High Efficiency Regulator $84.00 0-30V 3A Regulated DC Power Supply .......................... $37.00 0-20V 20A Professional Regulated Power Supply with Full Protection Circuit ................ $134.00 0-30V 20A Professional Heavy-Duty Regulator with Full Protection ........... $149.00 +/-0-35V 2.5A Dual Regulated Power Supply .. ... $48.00 0-30V 10A Professional Heavy-Duty Regulated Power Supply with Protector Circuit ..... $84.00 0-50V 6A High Effeciency, Cut-Off & Auto-Reset, Electronic-Protected, Regulated Power Supply .. . ... $89.00 INVERTERS K110001 Battery Fluorescent Light Driver.. ........................................................... $19.00 K200088 DC-DC 12V to +/-35V or +/-SOV 6A Max High Power FET Booster Transformer .............$120.00 PLUS MANY MANY MORE ... PHONE OR WRITE TO US FOR A COPY OF PRICE LISTS 100W PURE CLASS A FULLY SYMMETRICAL POWER AMPLI FIER K200040 (Mo no) $79.00 CHARACTERISTICS: • Dual differential inputs and fully direct symmetrical coupled circuits ensure heigh stability and low distortion. • With power transistors built-in the 8" Type C heavy duty heat sinks (1.6Ib approx), no extra wiring required. • Unique circuit design, high output power derived from the pairs of MS15003 & 15004 for collector outputs. • Frequency response rang e: 0-100KH z, distortion better than 0.001%. • Silvered fibre glass board . K210025 $48.00 ±0- 35V2.5A DUAL REGULATED POWER SUPPLY CHARACTERISTICS: It employs single potentiometer to control +V and -V in synchronization. So it will not output different voltages because the potentiometer is unbalanced. It is suitable for common pre-amp and miniature OTL or OCL power amp. It decreases much noise, so sound is clearer. The circuit design is elaborated and equipped with limiting protection. It is easy to build and it is worth the price charged. SM-333VIDEO/AUDIO SURROUND SOUND PROCESSOR $239 SM-333 surround sound processor employs the most updated integrated circuits as its heart. It is also equipped with a (DNA) Dynamic Noise Reductor systems IC made by "National Semiconductor" to particularly filter out the annoying noise that is commonly found on tapes or CD disks; therefore (DNA) system is suitable for and has outstanding performance on different video types, CD, LO, or Dolby Surround encoding disks and tapes, etc. In addition, there is six low noise operating amplifiers and all in one board design, no other external connections connect to the main board besides the power line, hence that makes the internal noise reduced to its minimum level, as well enabling, SM-333 to produce ultimate live performance effect. SPECIFICATIONS &ELECTRICAL CHARACTERISTICS: FREQUENCY RESPONSE : 20Hz- 20KHz+/-5dB Surround sound output T.H.D. (Front channel) : 0.05% 20Hz- 20KHz Voltage : 6.6V(MAX) T.H.D. (Rear channel) : <0.25% Delay time : 5ms- 50ms Input signal voltage : 0.1V-3.5V(MAX) Power : AC240V at 50Hz Front channel output Dimensions : Wide 360mm,(14.2in.) voltage : 0.1V-3.5V(MAX) Depth 122mm,(4.82in.) : 47Kohms Height 53mm,(2.10in.) Input impedance ~ SM-320 120W STEREO POWER AMPLIFIER $219 In order to match with the SURROUND SOUND PROCESSOR, our company has specially designed a 120W Stereo Power Amp. This amplifier not only acts as a perfect partner of Surround Sound Processor and many other audio sources. The special design of all components are soldered on one P.C. Board, therefore; connecting wires are deducted to the least, noise and distortion can also be avoided to the minimum. SPECIFICATIONS & ELECTRICAL CHARACTERISTICS: FREQUENCY RESPONSE : 20Hz-20KHz S/N RATIO BffiERTHAN 70dB TOTAL HARMONIC LOAD IM PEDANCE 40HM-80HM DISTORTION : LESS THAN 0.1 % POWERCONSUMPTION 130VA POWER OUTPUT : 60W/4 ohms, 33W/8 ohms per channel DIMENSIONS 360mm(W)x75mm(H)x220mm(D) INPUT SENSITIVITY 14" X 3" X 8-5/8" MIG LO HI MAIL ORDERS WELCOME: CHEQUE, MONEY ORDER, BAN KCARD, MASTERCARD, VISA OR AMERICAN EXPRESS. - -7)6. /,:.;~f~;f~:;)')~~~~-~~~. . ,~7-:-:.~. .--:~-- ~ ..~- ,,,, 11• ·•.... ~ ,. , . .., ; . -~, ,, ' • tf -• • ~ I .1;, , . I ,_,..,_ f , . 9 • ~ • • • .: . -, ·- -· -._ -~-_.- _. , . ·- -~----- ' ...._!\;; . • •; I • . • • . •,/!' . I TALKBACK POWER SUPPLY Build a multi-station headset intercom; Pt.2 Last month, we described the circuit of our new multi-station headset intercom & started the substation assembly. In this final article, we complete the substation & give the assembly details for the power supply. By MARQUE CROZMAN At this stage, the substation wiring can be installed as shown last month in Fig.5. This wiring is straightforward but be sure to use a short length of shielded audio cable for the microphone input (4-pin XLR). Pin 2 is the mic signal and pin 1 is ground. It is important to use shielded wire for these connections as the case is not shielded. Light duty hook-up wire can be used for the rest of the connections to the board. Keep all wiring as short as possible. 76 SILICON CHIP The PC board can now be slid into the slots cut into the case (see Fig.6). By slightly bending out the sides of the lower half of the case, the front panel can also now be installed. The rear panel is then slotted in and the top half of the case snapped into place. To be able to wear the substation on your belt, a clip needs to be riveted to the bottom of the case. These are the same type of clips that are used for tape measures, and can be found in some hardware stores. If the substation is being built with the auxiliary input, an extra hole needs to be drilled for the additional pot. An unbalanced phone jack can be used for the input on the rear panel. It will need to be placed between the 4-pin and the 3-pin XLRs. The earth for the phone jack can be taken from pin 1 of the 4-pin XLR. Power supply construction All the parts are mounted on a single PC board coded SC04104921. The component overlay for this board is shown in the diagram of Fig.9. There is provision on the board for a trimpot but this is not necessary- unless you want to set the output voltage to exactly 30V. Begin the board assembly by installing PC stakes at the external wiring points, then install the diodes, resistors and capacitors. The LM317 can now be installed. Its metal tab EARTH OJ1 SOLDER LUG ACTIVE BROWN ' ~ )II <l\l~t\.\.\'S r,~t"- t1'~'" ,j/ ICORD CLAMP GROMMET POWER TRANSFORMER 8S1 ~~POWER Fig.9: assembly details for the power supply. Install the LM317 with its metal face towards the rear panel. should be adjacent to the edge of the board and it should be mounted with its leads at full length so that it can later be bolted to the rear panel (see Fig. 10). Case assembly The case must be modified slightly by cutting away the slots in the base to get the transformer to fit. When this has been done, drill the transformer mounting holes and bolt it into position, as shown in Fig.9. The 3-way mains terminal block can also be mounted at this stage. The rear of the case uses an aluminium panel which doubles as a heatsink for the LM317. The various holes can all be drilled by using the Dynamark® label as a template. This label has crosshairs to indicate the centres for all holes, except the one for the LM317 mounting screw. The position for this is best found with the board temporarily mounted in the case, on two of the pillars. The LM317 is attached to the rear panel using a screw, nut and an insulating kit. Fig.10 shows the mounting details. Looking at our prototype, you will see that we have constructed the 2outlet version and this is also depicted JULY 1992 77 PARTS LIST Substation components 1 PC board, code SC01302921, 90 x 93mm 1 Dynamark front panel label, 90 x40mm 1 Arista UB-1 plastic case, 95 x 34 x 145mm (DSE Cat. H2503, Rod Irving Cat. H10114) 1 3-pin female XLR chassis mount socket 1 3-pin male XLR chassis mount socket 1 4-pin XLR chassis mount socket (male for Jands compatibility; female for Concert-Com compatibility) 1 illuminated momentary contact pushbutton switch (12V lamp); Jaycar Cat. SP-0750 or Altronics Cat. S-1510 1 SPST rocker switch (Altronics Cat. S-3210) 1 small fluted knob (to suit .miniature pot) 1 300mm length of light duty hook-up wire 1 50mm length of shielded audio cable 6 machine screws, nuts & lock washers 13 PC stakes 1 10kQ linear pot Semiconductors 1 LM833 op amp (IC1) 1 LM833 or TL072 op amp (IC2) 2 BC337 NPN transistors (01 ,03) 1 BC327 PNP transistor (02) 3 1N914 signal diodes (D8 ,D9,D1 0) 1 1N4004 rectifier diode (D7) 1 33V 1W zener diode (ZD1) Capacitors 2 470µF 50VW PC electrolytic 2 100µF 25VW PC electrolytic 4 10µF 35VW PC electrolytic 1 1µF 35VW PC electrolytic 2 0.47µF 35VW PC electrolytic 3 0 .1µF MKT polyester 1 .0047µF MKT polyester 1 220pF ceramic 1 100pF ceramic 2 47pF ceramic Resistors (0.25W, 1%) 3 820kQ 2 1kQ 78 SILICON CHIP 1 220kQ 1 100kQ 1 56kQ 1 47kQ 222kQ 810kQ 1 560Q 1 470Q 1W 1 330Q 1W 1 180Q 233Q 1 10Q Power supply components 1 PC board, code SC04104921, 46 x 60mm 1 instrument case, 200 x 160 x 70mm (Altronics Cat. H-0480) 1 black anodised aluminium panel (Altronics Cat. H-0486) 1 Dynamark front panel label, 55 x 190mm 1 Dynamark rear panel label, 55 x 190mm 1 30V 30VA transformer (Altronics Cat. MM-2008) 1 3-core mains cord & moulded 3-pin plug 1 cord grip grommet 1 100mm length of 20mm heatshrink tubing 1 240VAC illuminated rocker switch (Jaycar Cat. SK-0985 or Altronics Cat. S-3217) 1 panel mount 3AG fuseholder 1 3-way chassis-mount mains terminal block 1 3-pin male XLR chassis mount socket (or 2 the for expanded version; see text) 1 3-pin female XLR chassis mount socket (or 2 for the expanded version; see text) 9 machine screws, nuts and lock washers 2 self-tapping screws 2 solder lugs 4 PC stakes 1 300mm length of light duty hook-up wire 1 50mm length of shielded audio cable Semiconductors 1 LM317 voltage regulator 6 1N4004 diodes (D1-D6) Capacitors 1 2200µF 50VW PC electrolytic 2 10µF 35VW PC electrolytic Resistors (0.5W, 1%) 1 2.?kQ 1 120Q This aviation headset from Altronics (Cat. C-9070) is suitable for use with the Headset Intercom but note that the standard aircraft jacks fitted to the unit will have to be replaced with XLRjacks. in the wiring diagram of Fig.9. Don't drill and cut holes for four XLR sockets on the rear panel unless you are going to build the 4-outlet version. All exposed metal on the case needs to be earthed; ie, the rear panel and the transformer mounting screws. The rear panel is earthed by a solder lug secured just above the LM317, while the transformer is earthed via one of its mounting screws. Make sure that both solder lugs are in contact with bared metal to ensure a good earth connection. The mains switch and fuseholder terminals should be sleeved with heatshrink tubing to prevent any chance of accidental contact with the 240VAC mains. The rest of the wiring details are shown in Fig.9. Double check all wiring and the PC board assembly before assembling the case. The 250mA fast blow fuse can then be installed and the unit switched on with nothing connected. Use your multimeter to check the voltage between pins 1 & 2 of the XLR sockets it should be close to 30V. If not, switch off and check the parts layout on the board and the wiring. If this doesn't locate the fault, check the voltage across the 2200µF filter capacitor (ie, at the output of the bridge rectifier)- it should be close to 42V. If this is OK but the output of the LM317 regulator is incorrect, check the 120Q and 2.7kQ resistors on its ADJ terminal. If the output voltage is correct but This inside view shows the completed power supply unit. Keep all mains wiring neat & tidy & be sure to sleeve the switch & fuse terminals in heatshrink tubing to prevent the possibility of accidental electric shock. the power LED fails to light, check the orientation of the LED. If everything is OK, connect up a substation and headset and have a listen. If there is any buzz, check the earth connections and the proximity of AC cables to audio lines. The unit can now be fully tested by connecting a second substation and checking that the CALL function works ' ~ <V 17 2'. ~ -~-- . . : ., .., Headsets The choice of headset will of course depend on your particular application and budget. The most popular headset with professionals, in the theatre and film industries, is the Beyer DT109. It can be worn comfortably for long periods, without reducing the diameter of your head. They are most commonly seen on the heads of TV camera operators. There is a drawback though; they are not cheap! A cheaper version from Beyer is available but other companies such as Telex (model 500) and AKG also make reputable sets, that _are half the XLR WIRING STANDARDS ,. l ~ ~ "" and that speech can be transmitted back and forth between them. Pin No. . 3-pin XLRs 4-pin XLRs 1 Gnd Mic Gnd 2 30-36V Mic +ve 3 Audio Line Headphone +ve 4 . Headphone Gnd t This close-up shot shows the mounting arrangement for the power supply PC board & the LM317 regulator (see also Fig.9). ]UL Y 1992 79 TALKBACK POWER SUPPLY + + + + PIN1: GND PIN2: PWR POWERED IJl;iuqa TALKBACK SUBSTATION MICA INSULATING WASHER w,~jl SCREW { ll1lllll(3 1 10220 DEVICE Fig.10: mounting details for the LM317 3-terminal regulator. Smear all mating surfaces with heatsink compound & check that the rear panel mounting area is smooth before bolting the assembly together. Finally, use your multimeter to confirm that the metal tab has been correctly isolated from the case. price of the DT109. Unfortunately, they do have a tendency to induce fatigue if worn for long periods. For extremely high noise environments, such as in helicopters and light aircraft, the only way to go is to use aviation h eadsets. There are a few SILICON CHIP + + MIN - - CASE 80 PIN3: AUDIO UNPOWERED MIC + MAX LEVEL CALL Fig.11: here are the full-size front &.rear panel artworks for the power supply & substation. brands to choose from, David Clark being the most sought after, but you will have to change the plugs, as the aircraft standard is 6.5mm phone plugs. A very reasonably priced pair is available from Altronics (Cat. C9070) for $189.00. Note that if you build the Talkback Intercom for use in aircraft, you will be able to run it from the standard 28V DC supply. However, you would be wise to spray the interior of the case with a product such as Electrolube® nickel screening to provide shielding as aircraft are usually plagued with a lot of electrical noise (as well as acoustic noise). Alterna- tively, you may decide to build the Talkback Intercom into a metal case for superior shielding. If your system is for amateur use, headphone/microphone sets are available from most electronic stores starting at about $39. Most of these do not use enclosed headphones and hence let in external noise. But if your noise levels are not excessive, these are quite adequate. Acknowledgment Special thanks to Tony Moffat for suggestions and to Lindsay Hall Productions for the use of their headsets during the design of this project. SC FOR CHIPS...WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... WOOD FOR CHIPS... § TOOL BOX s :s. x'i ...._ :E ;2 ..... p..._ Q8 s: ~ :t (.) a: p ..._ Cl 8S: ~ :E (.) ~ u:. Cl ·g s: ~ :E (.) c:r: t2 Cl § ~ ~ a: t2 § s: ~ 5: (.) ~ u:. Cl ~ (Jj ~ i5 ~ u:. Cl § ~ 5: (.) a: e a8 s: (Jj ~ ,,_, ~ u:. § s: If you want to do a good job. you need the right tools andwe·vegot'em!Callinandcheckyourrequirements whether it's for your job or your hobby, we'll have the best quality and the best price. ALLEN -KEY-HT6 ALLEN KEYS 1.5-6mm 8 Sizes in Box CRIMPER-CS500 CRIMPING TOOLS RG58/RG59U COAXStripr CRIMPER-CS600 D-Sub Crimp Tool CRIMPER-HX2 RG58/59 Coax Crimper CRIMPER-TCT44 4 Pin US Pig Crimper CRIMPER-TCT66 6 Pin us Pig Crimper CRIMPER-TCT88 8 Pin US Pig Crimper CUTTERS ~~:~~~~:~1i1B CUTTERS-HT12 CUTTERS-CK3799 CUTTERS-CK3798 CUTTERS-CK3773 CUTTERS-CK3786 CUTTERS-CK3780 CUTTERS-CK3841 CUTTERS-CK3775 CUTTERS-CK3623 CUTTERS-HT13 CUTTERS-HT14 CUTTERS-MPC290 CUT-N-CLINCH CUTTERS-TRV-30-V :~~::i~~n~~~~~~~~? ·. ,,,,,, , _~ , ' a:, /~ ~ ~ ' - - -- 'Ill,• r.,i [til. ~1~-L - -- - - - -- 4 95 ' :rn 19.95 88.00 88 .00 29.95 29.95 34 ,95 104mm Diagonal Cutters 110mm Angld Fish Ctr 110mm Oblique Cutter 11 5mm Side Cutters 120mm Oblique cutter 110mm Side Cutters 120mm Side Cutters 135mm Side cutters 145mm Side cutters 104mm Mini End Cutters 11 5mm Diagonal Cutters Heavy Duty Cutter Cut and Clinch Tool End Cutters HOT AIR GUN 10.95 46 ,25 50 .60 44.10 55.05 47 .50 15.40 45.80 16.60 8.95 9.95 69.95 35.00 22.95 Dual Heat Hot Air Gun DRILLS and DRILL BITS ARLEC-DRILLNDRIV ARLEC Dril l N Drive DRI LL-ME12 5-14V DC Drill DRILL-SEH2330 Drill Set EZ-C7SC/1 0.70mm Carbide Drill EZ-CBSC/1 0.80mm Carbide Drill EZ-C9SC/1 0.90mm Carbide Drill EZ-CIOSC/1 1.00mm Carbide Drill EZ-C12SC/1 1.20mm Carbide Drill EZ-HSS.70 0.70mm HSS Drill EZ-HSS.80 0.80mm HSS Drill EZ-HSS.90 0.90mm HSS Drill EZ-HSS1.00 1 .OOmm HSS Drill EZ-HSS1.20 1.20mm HSS Drill FILES FILES-CK124P Needle Files HOLE PUNCH HOLE-PUNCH 16-30mm Hole Punch IC EXTRACTORS IC-EXTRCTN-TWZR 16 Pin Extraction IC-EXTRCTN-16 14/16 Pin Extrctn Tool IC-EXTRCTN-PLCC PLCC Puller IC-INSRTN-16 14/16 Pin lnsrtn Tool IC-INSRTN-28 24/28 Pin lnsertn Tool IC-INSRTN-40 40 Pin lnsrtn Tool KNIVES and BLADES X-ACTO No.1 1 Blades x 5 EZ3108 X-ACTO No.16 Blades x 5 EZ3110 EZ3141 X-ACTO CUT-ALL Knife KNIFE-SET-HT23 Boxed Set of 3 Knives NIBBLING TOOL NIBBLER-HT2049 Nibbling Tool NUT DRIVER NUT-DRIVER-HT11 5 Nutdrvrs 3 to Sm m PICK UP TOOLS PEARL-CATCH Sp rin g Loaded 3 Claw PICK-UP-HT27 Tweezers+ Magnet D TYPE PIN INSERTERS PIN-I NSERTION Pin Inserter for D Type PLIERS PLIERS-HT15 115mm Long Nose Pliers PLIERS-CK3767 Snipe Nose PLIERS-CK3770 120mm Flat Nose 145mm Needle Nose PLIERS-CK3783 PLIERS-CK3771 120mm Round Nose PLIERS-CK3772 120mm Snipe Nose PLI ERS-CK3777 150mm Snipe Nose PLI ERS-CK3769 150mm Snipe Nose-Bent REAMER REAMER-M422 Tapered Reamer SCRIBING TOOL SCRIBER-HT25 Scribing Tool 69.95 ARLEC-EHG998 /~~- ~ ~ 69,95 29.95 14,50 12.50 12,50 12,50 12,50 12.50 8.70 5.55 5.55 5 .55 3,50 33 .00 69.95 2.50 9.80 29.75 12.50 12.50 12.50 4.50 4. 50 5.25 19.95 19,95 17.95 3.95 11.95 4.25 9.95 35.10 33.10 36.60 29.50 34 .75 40".80 44.60 15.50 3.95 ASK FOR OUR FREE SEMICONDUCTOR LISTING SD-HT28 SD-ws 6252 SSDD:CCKK44888800:'i.3.5 SD-W 73101 SE>-CK4880 _4 SD-CK4880 _6 SD-CK4881-4 SD-W73104 SD-CK4880 SD-CK4881-6 SD-CK4975 SD-W74008 SO-CK4965 SD-W86982 SD-W7 4010 SD-CK4882 so-CK4882SD-W73501 SD-W73502 SD-W73503 SD-W94208 SD-CK4977 SD-W77003 SD-TORX-HT20 SD-TORX-W82010 .. ~o · ~ - - - -- -----' SCREWDRIVERS Stubby Ratchet Driver stubby XBlade 9.95 2.5x60mm XBlade Dvr 1 ~~ 1~i\~~de JxlOOmm XBlade Dvr JxlSOmm XBlade Dvr 4xl00mm XBlade Dvr 1~:;~ 6 60 6-00 · ~~:;~~~ r~~ 6·60 4xlODmm lnsltd Xblade 7.10 4xl50mm XBlade 6.60 4xl50m m XBlade Dvr 6.60 4x250mm XBlade 8.50 5.5xl25mm XBlade 8.50 5.5x300mm XBlade 10.80 6x25mm Xblade stubby 7 10 6.5xlSOmm XBlade 9:50 oox60mm Philips 11.45 1x80mm Philips 11.20 Ox60m m Phlps lnsltd 6.50 lx80mm Phlps lnsltd 7.65 2xl00mm Phlps lnsltd 9.90 02x25mm Phillips Stubby 7.10 250mm Philips 8 25 2xl00mm POZIDRIVE 8:95 1.5xlSOmm Torx for Mac 4.95 T.10 TORX Driver 11.20 POWER DRIVER BITS SO-BIT-W26724 2x4mm XBlade Bits SD-BIT-W26726 2x5.5mm XBlade Bits SD-B IT-W26720 2 Nol Phlps Bits SD-B IT-W26732 3 PhilipsBiB SD-BIT -W26721 2 No2 Phlps Bits SD-B IT-W26717 2 No2 POZIDRIVE Bits SD-BIT-W26716 POZIDRIVE Bits SD-BIT-W26735 TORX T-10 Bit SD-BIT-W26736 TORXT-15 Bit SD-BIT-W26737 TORX T-20 Bit SD-BIT-W26703 Extender SD-BIT-W27620 6 Assrtd Bits+Holder SD-BIT-W26713 7 Asrtd Bits+ Extender SO-SET-CK4854P Watchmakers Drivers SCREWDRIVER SETS SD-SET-CK4884 SO-SET-HT7 6 Pee Jwlrs Dvr Set SD-SET-HT8 Jewellers Philips Set SD-SET-HT9 6 Pee Jwlrs Dvr Set SD-SET-W18970 1OOOV 6 Dvr + Tester SD-SET-W20130 2 Phlps & 5 XBlade TEST DRIVERS SD-TEST-ES1 140mm Neon Test Ditr SD-TEST-B3226 Test Driver TIN SNIPS SNIPS-CK4531 250mm Tinsnips STRIPPERS STRIPPER-CS200 Stripper0.5 to 3.5mm STRIPPER-CS500 RG58/59 COAX Stri pper STRIPPER-CK3754 STRIPPER-KFLEX JOKARI Flex Stripper STR IPPER-KOAX2 JOKARI Coax Stripper STRIPPER-W/W Wire Wrap Stripper SUPERTOOL and BITS ARLEC-SUPER-TOOL 12V Drill/Grinder ARLEC-ET6 12 Eraser ARLEC-ET625 Drill Bits Pack of 4 ARLEC-ET627 Grinding Bits Pack of 3 ARLEC-ET643 Erasers ARLEC-ET669 Engraving Bits ARLEC-ET688 Diamond Engraving Bit ARLEC-ET689 Splitting Discs ARLEC-ET722 Wire Brushes Pack of 3 TOOL KITS TOOL-KIT-HT11 20 Piece Tool Kit TOOL-KIT-HT17 16 Piece Tool Kit TWEEZERS TWEEZERS-CK2302 115mm Straight Tweezers TWEEZERS-CK2312 150mm Clamp Tweezers TWEEZERS-CK2314 150mm 45d Tweezers TWEEZERS-CK2316 110mm StraightTweezers VICE VICE-MV3 PlasticVice Suction WIRE WRAP TOOL WIRE-WRAP-TOOL Wire Wrap Tool 8.30am to 5.00pm Mon to Fri. 8.00am to 12 noon Saturday. Mail Orders add $5.00 min to cover postal charges . Next day delivery in Sydney add $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. 4.75 4.75 4.35 10.70 4.35 4.70 3.75 6.50 4.75 4.75 11.25 20.50 23 .20 21.00 29.30 5.95 5.95 6.95 57.60 87 .95 2.45 3.35 32.50 16.95 19.95 28 .90 32.00 32.00 27.80 69.95 4.50 7.95 2.95 3.25 10.95 18.95 15.95 16.95 17.95 19.95 6.95 19.95 15.90 19.95 6.95 19.80 8~ New Electronic Workbench TJ.EJ . Lab , 11e ectromcs YESyoucannow bui ld, simulate and test Analog and Digital Circuits without raying vour hands on a single componentf W ltk'sbso eha®sy DwithIt Elle! ctrtohntichs or enc • · o a WI e mortuseb.- ddrag ntehw parts! frtohm the ~a s in , rop em on e 0 1 ct:iut~di; ~~~ioa~u;i~ i;es are re-routed automatically. It's much faster than buildin~ real circuits. No faulty parts! It S the result of 10 years innovation and thousands of students, hobbyists and engineers have been us ing the Workbench since its introduction in 1988 _ ° Ectl~~~ A I · / d na og Module me U es • Comprehe ns ive parts bin includes op-amps, zeners, transistors etc • Fu nction Generator with sine, square , triangle etc • Oscilloscope with dual trac e, inVext tri gger, nanosecond timebase upto 999MHz • Bode Plotter fo r freq uency responses and phase sh ift (-200 lo +200d8) • SPICE Simulation plus transient and steady-state simulati on you keep in your PC! o·1 1·t IM d I · Id Ua _Q.....,, 2 O U e me U es • Gomprehensive parts bin with gates, flip-flops, half adders, displays etc • Word Generator up to 16x8-bits • Logic Analyser with 8 channels, inVext trigger • Logic Converter converts gate, truth table and Prolessionalversion has inhanced colou r interface supports maths co' processo r. Requires IB M AT or PS/2 ·th 286 t h d disk g40kB RAoMr gMre_1acreors, ofatr ' ' mouse, EGA/VGA and DOS 3.0 . Personal Pl••W ersion is $429.00 monochrome. Requ ires PC/XT/ AT or PS/2 , 2 floppies or hard disk, 512kB RAM , Microsoft mouse, CGA/EGANGA/ Hercules graphis adaptor and OOS 3.0 or greater. $299.20 See the review in Electronics Australia March 92 "Electronics Workbench is certainly the easiest simulator I've ever used" Peter Philips 4:11 E\.~c, fh_ §c:, 23JJ 2 ;}l -;~::-;-~:--;----11~~=;~~===f1V~~~ New Lab 4 ~=;:~::;!;;:~!:I Everyth"1ng you need in a single • trumen t I■ ms Ideal for the professional and keen hobbyist. Saves bench space. High accuracy yet low cost. Ju st check the features - Function Generator • Sine, square , triang le, skewed sine, pulse, TTL level square • covers 0.02Hz to 2MHz • output from 0.1 Vpp to 20Vpp • Linear and Log sweep - 20ms to 2s (int) or 100:1 VCF (ext) • 50Q/600n output Frequency Counter • 1Hz to 100MHz • 15mV sensitivity to 60MHz e o.1 to 1OOHz re solution • 1Oms to 10s gate • 10MHz reference, with 5ppm stability • 8 digit display with annunciators Digital Multimeter e 3 1/2 digit LCD • ·• • • • Auto/Manual rang ing vdc, Vac,n , Ade , Aac fun ctions o.5% basic accuracy Data Hold Memory mode for relatiuve measurements and zeroing Q's Power Supply e 3 1/2 digit vo ltage display • Triple output eato 50V, 0.5A e 15v 1A and 5V 2A fixed • 1mv ripple • Full overload protection Incredible value -$837 .00 inc tax $722.00 ex tax NEW §c:, SC-7000 " DeSoldering Tool pii • • • • 23JJ 2 Now with 100W ceramic heater Work on up to 12 layer boards Special antistatic housing Optional surface mount kit $482 .50 ex tax $579 inc tax Appa 95 Multimeter Check these value features • 3999 count high resolution display • Eleven functions - Vdc, Vac, Ade, Aac, ohms, diode, logic, continuity, frequency, capacitance and transistor hfe • Peak hold button • Automatic power off • 0.5% basic accuracy • Shock prooffrom 1.5m drop $139 .00 ex tax, $166.80inc tax § tJ 23JJ QUV·T8/N Industrial EPROM Eraser r • 125x200mm slid-out tray with anti-static pad • UV indicator • 15,000microwatt/sq cm • 7700 hour lamp life • Safety interlock switch 23JJ $133.80 ex tax, $155.20 inc tax (inc in N SW) -iC\ -0 ~~~1::~ Geoff Wood Electronics Pty Ltd ~ ~ ,, ;£ (') ;£ §c:, ~ ~ § c:i ~ 229 Burns Bay Road,, Lane Cove West N SW 2 (Corner Beatrice Street) 'u Mail Orders to - P O Box 671, Lane Cove N S W 2066 [I) Telephone : (02) 428 4111 Fax : (02) 428 5198 §c:, I ~ 1/"•• ~ . "~-:'. Electronics workbench for home or laboratory Are you presently wprking under difficult conditions on an unsatisfactory workbench? You don't even have a workbench? Then cast your eyes over this design and see if it would suit your requirements. By LEO SIMPSON This workbench design was built for the SILICON CHIP workshop a number of years ago and it has generally proved to be practical and effective. We had four of the benches built in fact, and if we were having them built again we would only make slight changes. These changes have been incorporated into the dimensional draw82 SILICON CHIP ing (Fig.1) featured with this article. Our requirement was for a workbench that had plenty of space, was reasonably strong without being too heavy and which could be disassembled so that if and when we moved premises, which we did, the job would not be too onerous. A workbench for electronics assem- bly or service work should not be something slapped together after five minutes' thought. Nor should it follow the lines of a workbench intended for a carpenter or fitter and turner. Our first requirement was that the bench should not be too high - just a little higher than standard desk height would be right. After all, most electronics assembly or service work is done ·sitting down, not standing. Nor should the person concerned be perched on a stool - a comfortable office chair should be used. Overall dimensions The workbench needs to be large but not so large that you cannot reach the furthest corners without stretch- r 780 L ◄ Fig.1: build your workbench to the dimensions shown in this diagram. The bench top & shelving is made from particle board, while the sub-frame & side braces are made from DAR pine or Oregon. Do not use material thinner than that specified, otherwise the bench will not be strong enough. f --LEGS OAR 50x50 FINISHED BENCH TOP 18mm PARTICLE BOARD SHELF AND SHELF SUPPORTS 15mm PARTICLE BOARD DIMENSIONS IN MILLIMETRES Pictured at left is one of four identical workbenches which were designed and made for the SILICON CHIP workshop several years ago. The design has proved quite practical but sadly, they are never quite as tidy as presented here. The legs and side braces are made from 50 x 50mm DAR timber, while the rear cross brace is made from 36 x 36mm DAR timber. This should be glued and screwed together to produce a light, strong and rigid frame. Benchtop ing too much. That is one benefit of the L-shaped extension which can be attached at the right or lefthand end. We originally intended the extension table to be used for computers but it has not worked out that way. They are not quite deep enough to be convenient for most computers and certainly not' if a big monitor is to be used. However, the extension does make a very convenient extra work space, for spreading out diagrams , data books or whatever. Hence, the overall dimensions of the workbench are 1800mm wide by 900mm deep and 780mm high; ie, the same as a standard office desk except for a small increase in height. The extension measures 900 x 640mm. The top section is 305mm high and has a shelf 375mm deep. The workbench shown in the photo has a shelf only 305mm deep but that has proved to a little shallow for equipment such as oscilloscopes. The frame of the workbench is made from 75 x 50mm DAR (dressed all round) pine or Oregon (Douglas Fir) . The top is made from 15mm thick particle board. This is fitted with locating blocks on the underside so that it merely drops into place on the frame. The particleboard is covered with flooring vinyl which makes a very comfortable working surface. It does have two drawbacks though. First, if you drop hot solder onto it, it partly melts its way into the surface, making it very hard to remove. Second, the vinyl we used has a slightly dimpled surface which is not good for writing on. If we were making the workbenches a second time, we would specify a vinyl with a smooth surface. The problem of hot solder can be partly overcome by putting down a suitable piece of felt over your immediate working area. To protect the edges of the vinyl, an 18mm timber moulding is fitted all round. This should be nailed and glued into place. Sitting on the top of the bench is the shelf assembly which is made from 16mm thick particle board finished on all surfaces with white Melamine. The shelf assembly is closed in at the sides and back. This stops things roll- ing off the bench. On our prototypes, the shelf assembly was made from standard 300mm wide shelving but as noted above, the top shelf surface really needs to be around 375mm wide to accommo date equipment like oscilloscopes. Any unfinishe d edges of the Melamine surfaced particle board can be finished with iron-on Melamine veneer. The whole assembly is screwed together and to the benchtop with particle board screws. Do not use selftappers. They do not hold as well as twin-start coarse thread screws which are made especially for particleboard. The countersunk screwheads can then be concealed w ith white plastic covers which fit into the recess of the screw h ead. L-shaped extension The frame and legs of the extension section can be permanently secured to its top section. It is then bolted to the main bench, at either the right or lefthand side, depending on your preference. Electricity Many workbenches we have seen over the years have had unsatisfactory mains power outlets. It is a mistake to put them right at the back of the bench where you will have to keep reaching for them. Nor do you want the power points at the front edge of the bench where the power cords will constantly be in the way. JULY1992 83 Protect your valuable issues Silicon Chip Binders 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 up to 14 issues & will look great on your bookshelf. This photo shows a closeup of the Kambrook KDl 7 4-outlet power point used on both sides of the benches. These power points can be purchased from K-Mart for about $25 each. * High quality * Hold up to 14 issues * 80mm internal width * SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price : $A 11.95 plus $3 p&p each (NZ $6 p&p) . Send your order to : Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or fax (02) 979 6503; or ring (02) 979 5644 & quote your cred it card number. Use this handy form l ----------Enclosed is my cheq ue/money order for $._ _ _ or please debit my O Bankcard O Visa O Mastercard Card No: Card Expiry Date __/ __ Signature _ _ __ _ _ _ _ __ Name _ _ _ _ __ __ _ __ Address_ _ _ __ _ __ __ I I I I I I II II I I I . ___________ . _ _ _ _ _ _ _ P/code_ __ 84 SILICON CHIP Putting the power points at either side of the bench is a good compromise. We used a 4-outlet power point at each side of the bench. These are made by a number of manufacturers but in our view the one made by Kambrook, model KDl 7, is the best value for money. It has shuttered outlets and double pole switches and is presently available from K-Mart stores at around $25. The mains wiring to the two GPOs (ie, power points) should be run in 10-amp rated solid core double sheathed cable, specified as "1/1.13mm twin and earth". You will need about 3.6 metres of this cable. This is run in 16mm square plastic conduit with adhesive backing and a snap-on plastic top cover. Although the conduit does come with an adhesive backing (just peel off the protective cover and stick the conduit on) we also used screws, just to make sure. You will have to notch out the shelf supporting section(s) to accommodate the conduit. The square conduit is available from electrical wholesalers. To get the power to the bench, you will need a 10-amp rated flexible power cord with moulded 3-pin plug. The cord should be at least 2.5 metres long. The cheapest way to get this is to buy a ready made 3 or 5-metre long extension lead and cut off what you don't need. The cord is anchored with a cord clamp to the shelf assembly before passing through a 10mm hole in the particle board immediately behind one of the power points. It is then anchored again with a cord clamp and terminated to the back of the power point. Other refinements Having presented this design, readers will no doubt come up with their own refinements. For example, you could add a foot rest to run between the two side braces. If you do this, make sure you use adequate strength timber such as 100 x 36mm DAR, otherwise you may snap it if you apply too much weight. And if you do add the footrest , don't be tempted to omit the rear cross brace. If you do build a workbench to this description, it will cost you several hundred dollars for material alone but it will be money well spent in providing a practical and effective work space. And then don't forget to buy a reasonable office chair to go with it. After all, you may spend quite a lot of time sitting in it. We purchased gas-lift office chairs but with one modification. We had the central column extended by 10cm to give a little extra height. Most imported office gas lift chairs are sourced from Italy or the far east and they don't adjust quite high enough for the average Australian male. SC I PRODUCT SHOWCASE 100-channel scanning receiver The Uniden Bearcat UBC 760XLT scanner is a 100-channel scanning receiver covering the range from 66956MHz in 12 bands over the VHF and UHF spectrum. It features a backlit LCD, automatic search, five selectable band search presets, scan delay and direct keypad channel access. The unit can work as a base station or, by using the mounting brackets supplied, can be used as a mobile scanner. It is powered by an AC adapter or may be plugged into 13.5V DC. Sockets on the rear provide options for an external speaker, tape output and an external antenna. The 100 memory channels are broken up into five banks of 20. This allows for loop scans of separate bands or groups of bands. The scanning rate is 15 channels per second. A manual scanning operation will scan between any two frequencies and a priority feature will scan important selected frequencies every two seconds. Frequency selection and all programming functions are by keypad entry and all active functions are shown on the LCD display. It is priced at just $470, including the cost of delivery anywhere in Australia. Alternatively, if you require a compact handheld scanner, why not consider the Uniden Bearcat 50XL which has eight bands and 10 channels? It is priced at just $211, again including delivery. For more information about the Uniden range of scanners, contact Gary Carlson, TopCom Communications, 54 Corowa Crescent, Greensborough 3088. Phone (03) 883 9535. 12V to 240VAC 140-watt inverter This neat little inverter uses a high frequency switching circuit to obtain a 50Hz square wave output. By using the high frequency switching concept, it avoids the need for a bulky 50Hz transformer and thus saves· on weight and volume. It is rated for a continuous 140 watts output with 200 watts available on an intermittent basis. The size of the unit is 150 x 75 x 50mm and it comes equipped with a heavy duty plug to fit a car's cigarette lighter socket. Apart from the flush 3~pin socket at one end, there are two LED indicators: red to indicate that 240VAC is avail- able and green to indicate that the battery is connected. An audible beep gives a warning when the battery voltage is low. Branded My-Power 200, the unit sells for $199 at David Reid Electronics, 127 York St, Sydney 2000. Phone (02) 267 1385. I Double your memory with DR DOS 6.0 DR DOS 6.0 is Digital Research's latest version of its DOS compatible operating system for the PC and its many variants. Nobody calls it "Dee Ar" DOS by the way - they call it Doctor DOS. As with Microsoft DOS 5.0, DR DOS 6.0 has number ofutilities which make use of extended memory in 286, 386 and 486 machines but its whiz-bang feature is the ability to double your available hard disc storage using compression software called" SuperStor". In practice though, you would not elect to have all the disc space used in compression mode because some files cannot reside and be used properly in compressed form. This applies particularly to Windows 3.0 swap files. That aside, DR DOS 6.0 can be a cheap alternative if you are faced with a hard disc storage problem and cannot afford the money for a bigger disc drive. It is available from all Rod Irving Electronics stores in Sydney and Melbourne at $129.00. New solder dispensers from Scope This new solder reel holder can be attached in seconds to any of the Scope ETC60L series solder stations (or any other brand with a suitable flat top). This simple accessory should save JULY 1992 85 frustration and time looking for the solder reel some-one "borrowed" and also reduce bench clutter. Also available is the model ST51 portable bench top dispenser which can be used whether or not you have a soldering station. For further information, contact Scope Laboratories , 3 Walton St, Airport West, Vic 3042. Phone (03) 338 1566. 2.25Kb of RAM. In addition, a 32Kb program memory has been integrated into the corresponding ROM versions, SAB 83C515A-5 and SAB 83C517A5. For many applications, this means a significant reduction in external components. Both chips are available immediately. The new Siemens 8051 family use a maximum clock frequency of 18MHz. In the SAB 80C517 A, fast computation is supported by the integrated 32-bit multiply-divide unit (for example, division of two 32 bit/16 bit operands in 4µs) and by the eight data pointers. For further details, please contact Mark Walsh, Siemens Ltd, Advanced Information Products, 544 Church St, Richmond 3121. Phone (03) 420 7345. Appa 100 series multimeters r:~:..i r~l--~~,.tx J· 't! ·, r ~- "t:"'·. · •. , . Claimed to be the toughest multimeters available, the APPA 100 Series are protected by a thick-walled high impact, fire-retardant case with seals that protect against water and dust. The case is further protected by a rubber holster that has a tilt stand and test lead storage. Microcontrollers with expanded memory Siemens' new SAB 90C515A and SAB 80C517 A microcontrollers are the first 8051-compatible microcontrollers offering, respectively, 1.25Kb and THEV PRESTON ELECTRONICS 217 High Street, Preston, Melbourne Victoria 3072 (Cnr of Bell & High Street) OP MOD.EL RAILWAY : .,-.,S<-,.,,. • Quantum 50-Meg SCSI Hard Drive (1 only) $295.00 Fujits u 240V Coil Relays, DPDT 30A : .....·. •, , , . H .' . IN O .. ,. . • •• ,. ·.. $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 A look at some of the best Model Railways in Australia - * lnc!~des Australian, European, U.S. and U.K. layouts in all scales * Compare prototype locations in _Australia with the Mogel Layout * Visit all the recent exhibitions around Australia * AH technical detail explained 27512 Surplus Computer EPROMs, Erasable $6.95 QC-1910 Super Tiger 5MHz Oscilloscope $29.95 TEEPROM EPROM Writer Card/Cable + Software To Suit IBM-Compatible Computers $39.95 1r Mail Order Hot-Line Bf Card-Mast/Card-Visa-Cheque Phone (03) 484 0191 86 STLICON CHIP This is a high quality Broadcast Production featuring: Available from: CHOO-CHOO-CAM ACTIVE MEDIA IMAGES A Micro Camera mounted atop locos as they move around the layout PO Box 90, Riverwood, N.S.W. 2210 Phone: (02) 580 8525 60 minutes Running Time Cheque, Money Order, Bankcard, MasterCard or Visa Internally, the APPA 100 Series has high energy fuses , PTCs, sparkgaps and fusible resistors to protect it against unexpected overloads. Appa 100 Series multimeters are 3.75-digit with a 4000 count. They have a 42-segment bargraph display which is updated every 50 milliseconds. The 10 measuring functions incorporate Min/Max hold and Data Hold and Relative measurements. The meters are protected from 6kV transients on 660V AC feeders and have automatic power off. All models in the series are designed to IEC348 Class II and UL 1244 specifications. Recommended retail prices are $249 plus tax for th e Appa 103 and $299 plus tax for the Appa 105. They are guaranteed for three years . For further information, contact Tecnico Electronics, 34 Waterloo Rd , North Ryde 2113. Phone (02) 805 4422. CompactDFM checks to 1.2GHz This must be the most compact frequency meter on the Australian market. Measuring just 130 x 80 x 35mm, the Digitor WFC-308 frequency meter will measure from 20Hz to 1.2GHz in two ranges , A and B, which have separate BNC sockets. Range A measures from 20MHz to 1.2GHz while range B measures from 20Hz to 20MHz. One slide switch selects the A or B range and doubles as the on/off switch. The second slide switch gives a choice of three gating times, with the longer gating times giving greater resolution in the reading (up to eight digits from the red 7-segment LED display). A LED indicator above the display flashes to show the gating time selected; it is on for the gating interval. Input impedance on range B is 1MQ shunted by BQpF, while on range A it is 50Q Input sensitivity is claimed to be better than 15mV with a maximum frequency of 25MHz on range B. Our checks confirmed the sensitivity and we were able to measure to better than 28MHz before the meter dropped out. The Digitor frequency meter is powered by an internal rechargeable nicad battery pack or it can be powered and recharged from an external 12V DC plugpack (not supplied). It is available from all Dick Smith Electronics stores and sells for $199.00. Electronics Workbench® The electronics lab in a computer! a .K... ~ lli:1:ml:j::lli::J=t:lli±:i . _ -:------:--':-'-'--'-;'--'-'-c~ 000 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 . 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 ~ 0 ~- .. .. , THREE VERSIONS • Professional Version: EGANGA colour display; unlimited components • Personal Plus Version: Monochrome display; unlimited components • Personal Version: Monochrome display; limited to 20 components per ... EMONA INS TR U MENTS NSW ................. ........ (02) 519 3933 VIC ............................ (03) 889 0427 QLD .......................... (07) 397 7427 DISTRIBUTORS Perth ... .... .... .... .. ............ . (09) 244 2777 Adela Ide ........................ (08) 362 7548 Hobart .. .... ..................... (002) 34 2233 EmonaLAB4 Four instrum ents in one package! The LAB4 has four full function test instruments: ■ 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. DC POWER SUPPLY Triple output; 5V , 15V, 0-50V Sanyo VM-D66P 8mm camcorder ■ DIGITAL MULTIMETER ■ FUNCTION GENERATOR This camera's Bx zoom lens with macro close-up capability enables telescopic shots or wide angle panoramas. In addition, the macro area manual focus is ideal for shooting insects , flowers and other minute objects as close as 15mm to the subject. Built into the VM-D66P camcorder is Sanyo's fuzzy ■ Full function, auto-ranging 0 .02Hz-2MHz, with SWEEP • FREQUENCY COUNTER 1 Hz-1 00MHz 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 EMONA IN S TRUM E NTS 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 JULY 1992 87 logic which automates focus, exposure and white balance adjustments. With fuzzy logic auto focus, focusing becomes much smoother and faster. When your subject is not in the centre, the focus zone automatically expands to follow the subject and stay in focus, always following correctly as the subject moves. In addition, back lighting around a subject can often spoil a good shot but the VM-D66P's fuzzy logic automatically compensates to give correct overall exposure. The VM-D66P has shutter speeds ofl/50, 1/120, 1/1000 and 1/4000 second so that even the fastest action can be free from blurring. Other features include fade-in, fadeout, edit switch, auto date and time imprinting, recording review, linear time counter with memory stop, scene search, omnidirectional microphone, dew protection system, flying erase head and SP/LP modes. An infrared remote control can be used when the camcorder is connected to your television set. The VM-D66P from Sanyo has a recommended retail price of $1399. See it at your local video retailer. Surround sound processor has DNR This Mark V SM-333 surround sound processor produces a simulated surround sound field by using a bucket brigade IC to develop delayed signals for the rear channels. The delay time varies from 5-50ms, depending on signal content, and can be controlled from the front panel. Since the device is likely to be used to enhance the sound tracks of conventional video cassette recorders, a bonus feature is the inclusion of a National Semiconductor DNR (Dynamic Noise Reduction) chip to reduce high frequency noise. The SM-333 sells for $239 and is ATTENTION FAX MODEM OWNERS NEW SOFTWARE RELEASE available from A-One Electronics Pty Ltd, 432-434 Kent St, Sydney 2000. Phone (02) 267 4819. Fax/modem protector can check power points The Arista CPEP-1 is intended to protect modems, phones, answering machines and facsimile machines from high voltage transients and atmospheric disturbances (lightning) which may affect the phone lines, the mains supply or both. It contains gas arresters and metal oxide varistors (MOVs) to clip transients on the incoming mains lines. The incoming phone line is protected by a dual gas arrester. Low cost 19-inch enclosures Just arrived in Australia is the latest product release for your Class 1 or Class 2 fax modem : Quicklink II Fax WIN/DOS Combination This is the latest product release from Smith Micro Software. A 4-in1 software package which adds new flexibility to your fax/data modem. Features include: • Data Modem support in DOS • Data Modem support in Windows • Fax Modem (Class 1 or 2) support In DOS • Fax Modem (Class 1 or 2) support in Windows. The QL2FAX WIN/DOS Combination breaks the Windows/DOS barrier. For the first time, you have a true Windows application and a true DOS application which share the following common features : • The Send Fax Scheduler • The Send Fax Log • The Receive Fax Log • The Data Modem Phone List • The Fax Modem Phone List • The Setup FIie Information This means that if you schedule a fax in Windows, you can then close Windows completely, go back to DOS, and your fax wi ll still be sent. The reverse situation works in exactly the same way. No more multiple phone books for DOS and Windows. If you add to the phone book in DOS, it's still there when you work in Windows. You have a fax ph,:me book for fax modems/machines and a data phone book for data modems (BBS' etc) . Keeping them separate prevents mix-ups. Take advantage of the ease-of-use Wi ndows provides and fax straight out of any Windows application with the Quicklink II Fax WIN/DOS Combo. It's as easy as "FILE-PRINT'. Call for more information. $99.00 per copy, plus packaging and handling. Freight $7.50. PC MARKETPLACE PTY LTD PO BOX 1100, LANE COVE, NSW 2066. PHONE (02) 418 6711 FAX (02) 418 6713 88 SILICON CHIP A new range of economically priced, good quality 19inch enclosures is now available from M. Rutty & Co. Fabricated in mild steel and finished in a hard wearing black epoxy coating, the enclosures start at a low $58.18 for the smallest 1U model to only $109.38 for the largest, a 5U model. The base plate is punched with a matrix of holes for securing PCBs, transformers etc, while the top cover has ventilation slots. The black anodised aluminium front panel has two handles (except Model 03-120A) and there are four holes for securing the enclosure into the rack. The new range of enclosures complies with the standards IEC 297, EIA RS-310 C-1977, DIN 41494 and JIS C6010-1969. For further information, contact M. Rutty & Co, 1/38 Leighton Place, Hornsby, 2077. Phone (02) 476 2254. New mouse range for the Mac ARISTl\. MODEL CPEP, 1 ~ '4i!f ~¥!,,i·r~l~Jtt~8! tectric1an Unlit •·· All OK Earth • Ct AIIOK Unlit =--= Refer to electnc1an l'.QWl! • Ut ,:::AltOK Unllt "" Ae1er to electrician Connections to the incoming phone line and phone accessory line are made via US modular sockets. A bonus feature of the device is that it has three neon indicators which indicate whether or not the wiring of the mains power point is safe. A useful and well designed device, the CPEP-1 is available for a recommended retail price of $59.95 from Arista stockists throughout Australia. Australian peripherals distributor Mi-Lyn Imports has released the Animas range of mice (mouses?), including the first programmable optical mous e for Apple Macintosh computers. The new range features five models that cover the full spectrum of mouse technology including photo-mechanical, track ball and optical peripherals. At the top of the range is the OptiPRO mouse, a 3-button, programmable optical model with a resolution of 300 dpi. All three buttons can be programmed to suit the user's needs. You can allocate specific sequences, command keys or function keys and the main mouse button can be assigned to any of the three buttons, making it suitable for left or right-handed users . The Animas range retails from $95 for the Trac Mouse to $160, including tax, for the OptiPRO. All products come complete with ColorFrame graphics software, a detailed manual and a special mouse pad (except the Trac Mouse models). For further information, contact Michael Symons, Mi-Lyn Imports Pty Ltd, 4 Briar St, Fulham Gardens, SA 5024. Phone (08) 356 7337. 1Mb device with fast access speed This AMD 1-megabit flash memory, organised as 128K x 8 bits, features 5V programming and full sector erase operations. The device features access speeds as fast as 45ns and 100,000 write endurance cycles with completely automated program and erase operations. The Am29F010 , the first member of the family to be announced, will be shipping in volume by the third quarter of 1992. AMD's 5V architecture uses a sin- IAN J. TRUSCOTT'S ELECTRONIC WORLD 30 Lacey Street, Croydon, 3136. Phone (03) 723 3344; Fax: (03) 725 9443 Now also at: 200 Smith Street, Collingwood. Phone (03) 419 2808 Mail & Credit Card Orders Welcome · *** SAVE ON OUR JULY SPECIALS*** Our specials this month include 3-hour VHS video tapes from $3.95 and the famous Portasol gas soldering iron, normally $39.95, which is offered to SILICON CHIP readers at the crazy low price of $29.50. CAR RADIO AM/FM Autostop Cass/Radio ...... .. ............................. $39 Tenvox TX880 Cassette/Radio *Autorev/fader/clock/Dolby/loudness *hi-power/separate bass & treble .... ................. $194 Japanese Built CD Players ...................................... $398 4-inch Dual Cone 20 Watt Spkrs (pr) .... .. ..... .. .. ... .. ... .. $28 4-inch Co-Axial 35 Watt Poly Spkrs (pr) .................... $49 200 Watt Tenvox Car Amplifier ................................. $139 Quality 3-Way Box Speakers ....................... ..... .. .... ... $49 D25 Male to Male 2m/5m ............ ...... ............ $8.95/$9.95 IBM Keyboard Extensions ........................ .. ............. $9.95 D9 Male/D25 Female Adaptors ............................... $7.50 CB RADIO Compact 40ch SSB CB (new model) ...................... . $249 Itron CB Base Antenna (incl. mount kit) ... .. ........ ........ $65 Tenvox CB 1 extension speaker ............. .. ............ .... ... $12 5ft Helical Whips from ................................................ $12 Uniden UHF CBs from ........... .. ...... .. .... .. ................... $295 Marine CBs from ........................................................ $95 Itron 24/ 12 Volt 3 Amp Convertors .................... .......... $39 Electronic World is the home of all Itron CB & car radio accessories COMPUTER CONNECTORS Quality connectors, leads and adaptors at great prices, including DB9/25 and IDC connectors, ZIF sockets and many new popular memory ICs. D25 Male to Centronics 2m/5m .................... $8.95/$9.95 Ask about our great range of kits & TV antennas JULY 1992 89 for cutting copper and aluminium cable up to 6mm in diameter. They will also cut steel cable to a diameter of around 2.5mm. Their overall length is 215mm and their han dles have a red plastic coating. They are available from all Jaycar Electronics stores at $9.95 (cat. TH1823). gle transistor flash memory cell which provides dramatic re ductions in power consumption during program and erase operations (significant in battery-powered applications). With this technology, current AA battery-powered palmtops will now be able to use flash technology. The Am29F010 requires approximately one third the system level power of 12V flash devices during code updates. For further information, contact VSI Promark Electronics Pty Ltd, 16 Dickson Ave, Artarmon 2064. Phone (02) 439 4655. Spirit level set for hobbyists 1 '"y~~..,,,.-~,•;'"' 0 Big cable cutter from Jaycar So many people ruin their small pliers and cutters by trying to cut cable which is just too thick. You can avoid this problem with a pair of these cable champers which are suitable Mini vacuum cleaner for computer keyboards Are you interested in spirits? Probably not if you are reading this magazine, but you may well have a need for a set of spirit levels. This set features a torp edo level for checking horizontal, 45-degree and vertical surfaces, a string level, surface level and an angle level. The latter has a pointer which reads off surface angle to the horizontal. The full set is reasonably priced at $19.95 and is available from Rod Irving Electronics stores in Sydney and Melbourne. This little vacuum cleaner is intended for those fiddly jobs where a full size vacuum cleaner is not suitable. Examples are cleaning the dust off camera lenses, computer keyboards, model train layouts, art and craft items and so on. It comes with two nozzles and two very soft brushes which should be good for even the gentlest of dusting jobs. A screw-on bag with a Velcro flap is supplied for collecting debris but we found that it slightly reduces the effectiveness of the unit as a vacuum cleaner. In fact , it works much more effectively as a blower than a sucker! The unit can be powered by a 9V alkaline battery or a 9V DC plugpack. It is available at a very reasonable $9.95 from David Reid Electronics, 127 York St, Sydney 2000. Phone (02) 267 1385. Comma Corporation releases modem range SUPER BARGAINS - BULK PACKS & KITS All prices $A include sales tax. HURRY for stocks at current prices. Ask about Student Discount. PASSIVE INFRARED SENSOR Quality Dual Element PIA SENSOR (with data sheei plus PCB MOUNT FRESNEL LEN $8.76/set with changeover contacts 10 Pack $7.27 PCB MOUNT SWITCH DIODES & LEDS IN4004 100 Pack $6.20 WO410 Pack $3.95 RED LED 5MM 100 Paek $8.30 GREEN LED 5MM 100 Pack $10.60 LM380 10 Pack $13.05 LF35t 10 Pack $7.27 TL064 10 Pack $11.17 LM324 10 Pack $5.05 NE553410 Pack$15.16 CMOS -10 Packs 4013 $5.52 4060 $8.04 4049$5.02 4066 $5.56 4050 $5.52 40106 $5.52 OPTO·COUPLER 4N25 10 Pack $6.95 LINEAR LIGHT ALARM KIT Sounds when lighl enlers protected area. $12.41 MEMORY 2716 5 Pack $38.00 2114 10 Pack $19.43 6116 5 Pack $18.50 CRYSTALS CPUs ZBOA CPU $3.76 each 90 SILICON CHIP 4.0000 MHz 5 Pack $6.11 4.1943 MHz 5 Pack $6.11 1/4W CARBON FILM RESISTORS Any Normal Value 100 Pack $1.40 CAPACITORS 0.tµF 100V mylar 100 Pack $3.50 10µF 50V electro 100 Pack $5.90 VOLTAGE REGULATORS LM7805 10 Pack $6.67 LM7905 10 Pack $6.39 LM723 10 Pack $6.76 CONTINUITY TESTER & LONG LIFE FLASHER KIT Can distinguish between resistances in lhe range 0. 1 to 500 ohms. $13.93 STAIRWAY TO HEAVEN KIT Game ol skill lo reach lop of slairs. $21.98 Pack, Post & Ins: Aus $5, NZ $12 Discount: $5 off next order for orders over $150. Valid lor 3 months. Orders: Tel. (03) 751-1989 or PO Box 934, Mt. Waverley, Vic. 3149. Allow 14 days delivery. Bankcard, Visa, Mastercard Minimum $15 1000s of Components 'Respected name brands. •All bargain prices. 'Catalog free with order. Mr Phil Gleeson, a director of Comma Corporation, has announced a ra11ge of high speed modems with fax/send/receive functions. Designed in Australia and with full Austel approval, the range will include models that cover baud rates from 300 to 14,400, with 9600 baud fax send and receive. The top-of-the-line model will cover all data standards from 300 to 14,400 baud, with an upgrade to the new Vfast 19,200 baud standard when it is ratified. It also has V42bis data compression and error correction, as well as high-level security features. It is priced at $799 including sales tax. For further information, contact Phil Gleeson at Comma Corporation, PO Box 1100, Lane Cove 2066. Phone (02) 4187611. roNLV 0::z ONLY $249. 00 a: $699. 00 0 (.) iMil3=U~rJtl: <C <C Pfii[ (jfeeson's PC MARKETPLACE P/L TEL (02) 418 6711 FAX (02) 4186713 Mail Order Address: <C P.O. Box 1100 Lane Cove NSW 2066 :::, for month of issue Dealer enquiries welcome. 0 a: 16-ppm laser printer from Facit uses RISC-based graphics controller Facit has released the model D7160 laser printer which features 16 page/minute throughput on continuous forms. The printer uses a RISCbased graphics controller to provide industrial labelling and graphics capability. The D7160 can also be used as a high-speed low-cost alternative to line printers, with an equivalent throughput of 1024 lines/minute. It emulates IBM Proprinter and QMS Magnum Code V, Text Mode (Line Printer) and features optional IBM Twin-Ax/Co-Ax interfaces, making it compatible with a wide range of computer systems. Print capabilities include variable size characters, 40 barcode types and auto-incrementing of number fields. Free WYSIWYG software for label creation is also available. Logos, forms and other graphics can be downloaded and stored in the printer. The Facit D7160 prints on a wide variety of media, such as polyester, vinyl, mylar and tag stock in widths ranging from 11.4cm to 25cm and unlimited length. A straight-through paper path with self-centering tractors ensures reliable feeding. For more information, contact Paul Twigg, Elmeasco Instruments Pty Ltd, 18 Hilly St, Mortlake 2137. Phone (02) 736 2888. Upgrading PC memory - Hypertec's two new guides Hypertec has published an updated and enlarged issue of the "Memory Configuration Guide", which contains everything you need to know about upgrading PC memory. The 56-page guide identifies the appropriate manufacturer's product and the Hypertec equivalent for any particular configuration. Hypertec has also released a new edition of "Understanding PC Memory", a 28-page booklet, also supplied free on request, which explains machine architectures, types of memory, how memory is used and how it works with the 80386 processor. Hypertec memory products include upgrade boards, the best known being the Hyperam MC 32/16 for the complete range of Micro Channel machines and the Hyperam Classic, for classic architecture machines. Through its Chip Upgrade Service (CUS), a whole range of memory upgrades are offered for Hyperam boards, PC motherboards and other expansion boards. For further information, contact Katherine Doric by phoning (02) 805 0111. SC =.--~--·........ ---· = a "T""..:=.1 I f2LL z (.) Major Credit Cards accepted. Prices apply ~ ATTENTION : FAX / MODEM OWNERS If you are using QL2 3: 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. 0 z UNIDEN SCANNERS The Unlden 50XL is an economical handheld scanner with 10 channels covering 10 bands. It features keyboard lock to prevent accidental reprogramming, an audible battery low warning, channel lockout and a splashproof case. Also designed into each 50XL is a handy belt clip and patented track tuning for optimum reception. $211 i i The 1OOXLT scanner builds on the 50XL with 100 programmable channels and 11 band coverage, that includes the air band. Features include priority channels, auto search, scan delay and rechargeable battery. $399 The 200XLT sets a new standard for handheld scanners in performance and reliability. This full featured unit has 200 channels in 10 scanning banks with 12 bands of coverage, including aircraft and cellular frequencies. It featu res automatic and manual band search to find new active frequencies. A rechargable battery and charger are supplied. $470 The 760XLT (pictured) adds the 350-406MHz military and aviation band to complete the ultimate base/mobile scanner. Its 100 programmable channels combined with a size of 61/5" W x 1 5/8" H x 7 3/8" D produce the smallest full featured scanner available today. Combine it with a design that wouldn't look out of place in an art gallery er a top quality European car, and you have the ideal no-compromise scanner. $470 . • Frequency S0XL 66-88MHz ✓ 118-136MHz 100 XLT 200 XLT 760 XLT ✓ ✓ ✓ ✓ ✓ ✓ ✓ 136-174MHz ✓ ✓ ✓ 406-512MHz ✓ ✓ ✓ ✓ ✓ ✓ 806-956MHz TopCom Radio Communications, PO Box 336, Greensborough 3088. Ph (03) 883 9535 Fax (03) 432 0716 JULY 1992 91 ASK SILICON CHIP Got a technical problem? Can't understand a piece of jargon or some technical principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Signal tracer for UHF CB sets indicate an interest, we'll go ahead and do it. As I have an interest in electronics, I am often asked to fix the odd CB radio. The 27MHz sets are OK to work with but UHF.sets are another matter. What I would like is an instrument to measure the gain increases in the predriver and driver stages. It would not have to measure actual power levels - relative levels would be sufficient. At least you would see an increase from input to output and it would allow you to isolate the fault to a certain stage. As I am not able to design measuring equipment, would you have any ideas on this subject? Perhaps you could publish a suitable article? (R. L., Broken Hill, NSW). • What would be needed is a UHF preamplifier and detector circuit which could be hooked up to a digital multimeter to measure the relative signal levels. This should not be too difficult to design but we are not sure whether it would have much interest for many of our readers. If readers Resistors with six colour bands Powering audio equipment in the bush I am writing to enquire if you would have any information on the following. I have a Marantz SD530 tape deck and a CD73 CD player, together with an amplifier and speakers. My problem is that my house only has a 12V/24V DC system of electricity, as it is over 100km away from the nearest grid supply. Is it possible to convert these items over to the 12/24V system? If this can be done it would save me from having to sell this system. To top this off, I also have an IBM clone computer to do the same thing with (the monitor especially). Any information on how to do this 92 SILICON CHIP Almost every time you publish a project, you give a list of the colour codes for the four and 5-band types. I find this very helpful but the other day I was surprised to see a piece of equipment which had a few resistors in it with six colour bands. This is a real worry. I can cope with the idea of five colour bands (just!) but six bands is just too much. Can you tell me why there is any need for six bands? (L. Z., Kilsyth, Vic). • Cheer up! There is no need for you to learn yet another colour. Those resistors with six bands are pretty rare and will only be found in fairly specialised circuit applications. Resistors with six colour bands have the first five bands devoted to the value and tolerance and the sixth band gives the temperature coefficient. The colours are brown for 100 parts per million (ppm); red for 50ppm; without having to use an "ampguzzling" inverter would be very much appreciated. (A. C., Nambucca Heads, NSW). • Most audio equipment, including the models you have listed, would require balanced supply rails of at least ±15V to run the op amps. This means, inevitably, that you will need an inverter of one kind or another. Unfortunately, the same thing applies to IBM clones and their computer monitors. They all need some sort of inverter to run them. The only exception to this rule would be portable audio equipment which already has facilities to run from external DC supplies or automotive audio equipment which can run from 12V. orange for 15ppm; and yellow for 25ppm. The temperature coefficients for metal film resistors are usually positive with means that an increase in temperature of the resistor leads to an increase in resistance. As an example, a lMQ resistor with a temperature coefficient of 100 parts per million can be expected to increase its value by l00Q for every 1°C increase in temperature. Hence, if the temperature of the resistor goes up by 50°C, the overall increase in resistance can be expected to be 5kQ In most circuits, this would not be significant but it could be a problem in timing or voltage sensitive circuits. By the way, if you are faced with a resistor having six colour bands, by all means see if you can work out the resistor value from the colour code. But if all else fails, just measure the little blighter with your trusty digital multimeter. Compatibility problem with the line grabber Some time ago, I purchased two of your "Single Version Line Grabbers", as described in the March 1988 issue of SILICON CHIP. I put them both together and double checked all the PC board work. I then placed them in circuit with the phones in our house and things worked OK. A problem has now developed with the line grabber in conjunction with a Telecom TZ00 Touchphone. What would happen is that when the handset of the TZ00 was picked up, the engaged tone was immediately heard. After pressing the hang-up button a few times, the normal dial tone was produced. The phone in my room never had any problems while connected with the line grabber. The phone in my brother's room was not always connected and while fault finding, I had this phone disconnected from the circuit. After the line grabbers were removed from the circuit, the TZ00 operated normally. I have also swapped the two line grab- bers around but the fault persists. Any help that you can give me is greatly appreciated. (S. H., Summer Hill, NSW). • First off, we don't think there is anything wrong with your line grabber but rather that there is a problem of incompatibility between the line grabber and T200 Touch phone. As we understand it, the TZ00 draws significant current from the phone line at all times. This is different from other electronic phones which draw negligible current when "on hook". Their redial memory is nonvolatile and so needs no voltage to maintain it. The fact that the TZ00 Touchphone needs to draw current all the time probably means that when it is disconnected by the line grabber, as it would be when another phone grabs the line, it will malfunction when reconnected. TZ00s are also known to cause problems when connected in parallel with fax machines, modems and some answering machines. A less likely reason for the malfunction is that the line grabber reduces the voltage available to the phone when it is taken off hook. Possibly, this could be corrected by deleting the bridge rectifier in the circuit for the TZ00 phone. The 1.2V less voltage drop may get the phone going. Delete the bridge rectifier by removing diodes D1-D4 and replace Dl and D4 with links. Note that the polarity of the phone line must be correct with the pin 2 line positive. If this is not the case, swap the wiring to pins 2 and 6. However, we favour the first explanation but either way, it really means that you cannot use the line grabber, in its existing form anyway, in conjunction with the TZ00 Touchphone. LOPT tester for TV servicing I am seeking your assistance in sourcing a circuit for constructing a television LOPT (line output transformer) tester. I understand that a circuit may have been published in SILICON CHIP based on solid state devices. If you could assist me in finding a circuit, it would be much appreciated. I subscribe to your magazine and find its contents of great value. (L.B., Te Aroha, NZ). • Unfortunately, we have not published such a device and nor do we Lower speed range on optical tacho I'd be much obliged for some hell? on the optical tachometer which was described in the May 1988 issue of SILICON CHIP. What I'd like is to have ranges of 500rpm and Z000rpm rather than 2000rpm and 25,000rpm. Would this mean no more than changed values in the VRl, 10kQ fixed resistor and VRZ area? Secondly, on reading the article, and with experience of having to calibrate and re-calibrate other kits, I'd like to bounce this idea off you. Instead of using the 0. lµF capacitor temporarily during calibration, how about wiring one leg of this via a DIP switch? This leaves it available for calibration during service life so that calibration can be done at any time. Speaking as a know of any magazine that has published such a circuit. Maybe you should contact the TV service organisation in New Zealand to see if they have information. Howl suppression for PA systems I have several inquiries to make regarding the article on "Howl Suppression for Public Address Systems", as printed in the June 1991 issue of SILICON CHIP. (1) Is there a PC board available for this project? If so, from whom can I obtain same? (2) Would this suppression system give satisfactory results with a Philips EV4490 mixer? This unit was installed about 1972 or thereabouts. The amplifier is a 2-stage push pull tube type, the finals being a pair of 6CM5s. I have had very little to do with audio equipment. I have only worked with RF in the VHF & UHF sections of amateur radio and have now been requested to maintain and improve this installation. All or any suggestions would be greatly appreciated. (W. P., Werris Creek, NSW) . • Because of the experimental nature of this circuit, no printed circuit board was designed. Nor can we state whether the circuit would give satis- fully qualified non-expert, would shielded cable in lieu of standard hook-up wire be required here that's if the basic suggestion meets your approval? Thirdly, is there any objection to using a mirror at 45 degrees to simplify readings 6n shafts in either vertical or horizontal planes and even to obviate (as per your warning) turning the meter upside down? (J. R., Toodyay, WA). • You should be able to change the scaling by altering the 10kQ resistor to l00kQ and changing VRl to a value of lMQ. The idea of using a DIP switch to connect the calibration capacitor is a good one. We don 't think it would be necessary to use shielded cable, provided the leads to the switch were kept short. Using a mirror should be quite practical too. factory results or not but in principle, it should be workable. It could be difficult to adjust, however. Notes & Errata 40-watt Inverter, February 1992: a number of kitset suppliers have produced a 60VA version of this project with the upgraded M2165 transformer. However, some kits have been supplied with incorrectly phased transformers. When the circuit is connected as described in the article, the two Mosfets are likely to be destroyed. The problem can be overcome by checking the phasing of the transformer and rewiring it so that the two 0V tap connections become the centre tap. In the event of any damage, all claims regarding faulty transformers should be referred to the retail outlet where the kit was purchased. Telephone Intercom, May 1992: the 5-band colour code list for the 1500 resistor 6n page 63 is incorrect. The correct colour code is brown green black black brown. Video Switcher, June 1992: the type number allocated to the PC board should be SC02206921 , not 02204921. The latter number applies to the modulator board used in the TV transmitter for VHF VCRs, published in the March 1992 issue. SC JULY 1992 93 ........ T CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. r------- ------------------, : CLASSIFIED ADVERTISING RATES Advertising rates for this page : Classified ads: $10.00 for up to 15 words plus 40 cents for each additional word. Display ads (casual rate): $20 per column centimetre (Max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly on the form below or on a separate sheet of paper & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02) 979 6503. : I I I ANTIQUE RADIO ANTIQUE RADIO restorations. Your one-stop radio repair shop. Specialising in restoring vintage radios including chassis rewiring, re-condensing, quality new parts, valves, valve sockets, speakers, power & audio transformers. Secondhand radio dials & parts for most brands & models. About 400 radios in stock for sale, restoration & parts. Every restored wireless is covered by a 2year warranty on parts & labour. We restore damaged woodwork & cabinets & French polish (approx. 40 coats). Vintage car radios available for sale or restoration. Repairs done on tape decks & amplifiers. Open Sat. 10am-5pm ; Sun. 12.30-5pm . 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 7261613AH. FOR SALE MY AUSTRALIAN DESIGNED low cost super fast Z80 micro-controller development system has gained acceptance already with educational institutions. Pop it on the end of any PC MS-DOS or Z80 machine & away you go. Boards, EPROM & 720Kb disc $76 including postage for a short form kit. Gee, I wish I had this when I was a kid. For more information, send a 45c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine, Vic 3043. Phone (03) 338 6286. Enclosed is my cheq ue/money order for $._____ or please debit my o Bankcard Card No. O Visa Card O Master Card '----'------'L__L__I IL__L--.. L. ___~I IL__L__l____JI IL__L__l____J Signature_ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_ __c/_ __ Name _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Street - - -- - - - -- - - - - - ~ - - - - - - - - Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ _ _ __ XI I I I I I I I I I L--------- ----------------~ 94 SILICON CHIP WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" $35 is a high resolution, shortwave weather fax, Morse & RTTY receiving program. Needs CGA, SSB HF radio & Radfax decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same . as RADFAX2 but suitable for 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 post- MEMORY EXPANSION PRICES AT MAY 3RD, 1992 SIMM 1Mbx9 BOns 1MbxB 100ns 1Mbx8 80ns 4Mbx9 80ns 4Mbx8 BOns 256x9 sons (FOR SIP ADD $1) TOSHIBA T1 DOOSE 2Mb T2000SX 4Mb T1600 2Mb T31000SX 2Mb T3200SX 2Mb T3200 3Mb T5200 2Mb T2000SX 8Mb $48 $43 $48 $183 $175 $16 $230 $320 $140 $135 $135 $230 $150 $760 DRAM-DIP 41 1000 80 256 X 4 80 41256 80 1Mbx480Z 1Mbx480S $540 $5.60 $2.00 $25.00 $25.00 DRIVES 3½ PANAS 1.44 $80 S'GATE IDE 64/16 $420 S'GATE IDE 42/28 $325 S'GATE IDE 108/16$475 S'GATE IDE 130/16$530 CO-PROCESSORS 387/33/40 $235/$280 387/20125 $210/$215 SX 20/25 $155/$170 287110/20 $100/$125 Sales Tax 20%. Overnight Delivery Credit Cards Welcome. PELHAM Tel (02) 980 6988 Fax (02) 980 699 UNIDEN SCANNERS DON'T PAY MORE! 50XL RRP $299.95. Our price $211 10 memories, Lo-Hi VHF, UHF 100XL,T RRP $449.95. Our price $409 100 memories, Lo-Hi VHF, Air, UHF 200XL T RRP $549.95. Our Price $477 200 memories , Lo-Hi VHF, Air, UHF, 800 MHz CB, SCANNERS MARINE For more information, write to: TopCom Communications, Reply Paid 336 (no stamp) PO Box 336, Greensborough 3088. Phone (03) 883 9535. Fax (03) 432 0716. 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. KIT REPAIRS Kits repaired from all magazines. Switchmode power supplies repaired . Design work from start to finish. Computer software consultancy. Ring any time 9am-9pm Mon-Sun EEM ELECTRONICS 10 Bouverie Place, Epping, Vic 3076 Phone(03)4011393 age. Only from M. Delahunty, 42 Villiers St, New Farm, 4004 Old. Phone (07) 358 2785. VARIABLE TUNING CAPACITORS: brand new military quality metal 4-gang tuning capacitors - $10 ea. * SOLID STATE RELAYS: will switch 240V/10~ from 3-32V DC - $15 ea. * SOLAR PANEL: one watt into 6-8V loads, 150 x 150 x 2.5mm - $10 ea or 10 for $85. * MONOCULAR IR NIGHT VIEWER: complete small scope, plus kit power supply - $269. * MAINS OPERATED LASER: new 4mW tube plus a potted power supply - $249. * LCD DISPLAY MODULE: 16 x 2 with provision for backlighting - $22. * FLUORESCENT BACKLIGHT: for Citizen colour TVs, glows brilliant white whilst drawing 50mA from a 6V battery- $12. * LARGE LCD DISPLAY MODULE: Hitachi LM215XB, 480 x 128 dot display, as used in laptop computers, includes 4 pages of data - $39 ea. * LASER DIODE POINTER: pen sized 5mW pointer in presentation case - $199. * LASER FIX-A-KIT KIT REPAIR & CONSTRUCTION Plans Kits & PCBs 100W Valve Amp PCB ............... $30 Valve Amp PSU PCB .... .............. $25 Universal PSU (±5/±12) Dual Supply .................. ........... .. ... $10 Digi125 1OOW amp/pair ...... ....... $10 ETI 1623 PIA for PCs ................. $40 Max 1/0 Board ........................... $40 Max kit.. ..... .............................. $169 LM380 3.5 amp PCB ................... $7 AEM 35W amp kit ...................... $20 ETI Audio Toolkit PCB ..... ... ........ $10 AGC Amp PCB ................. ............ $7 Z-80 Miniprocessor PCB ........... $50 6502 Miniprocessor PCB ...... ..... $50 6809 Miniprocessor PCB ........... $50 8048/8049 Developers board complete B& T .. ....... ...... ...... $199 IBM PC Prototype PCB ...... ........ $50 EPROM Programmer ............... $299 ESL-1 Electrostatic speaker kit/ pair inc manual .......................... $899 ESL-1 Assembly manual ............ $50 P.C. Computers (08) 332 6513 36 Regent St, Kensington SA. 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE HVCAL ELECTRONICS Design. Manufacture & Repair of Electronic Equipment Forty pages of dreams! z ID ::e (02) 633 5477 DIODE GUNSIGHT: small adjustable 5mW unit with one pistol or rifle mount $299. * VISIBLE LASER DIODE HEAD: 3V battery operation, 5mW/ 670nm - $135. * BINOCULAR IR VIEWER: clip over a standard helmet on special at $550. * 12V OPERATED LASER: one used 3mW Siemens laser head plus a 12V inverter kit - $99. * 12V OPERATED LASER: one new 1mW tube plus an inverter kit - $149. * MAINS OPERATED LASER: new 1OmW tube plus a new potted mains power supply $389 . * 12V LASER BARGAIN: 12V laser inverter kit plus one of our "mystery" tubes, you won't be disappointed $89. * 40kHz ULTRASONIC TRANSDUCERS: $4 for a pair, 40kHz Xtal $3.50. * SECOND GENERATION NIGHT VISION TUBES: very small fibre optically coupled tubes that will perform under starlight illumination, rejects with some blemishes - from $500. * STEPPER MOTORS: 5V, 7.5deg, 6.6ohm, 2-phase - $12. * DUAL TV ANTENNA: Panasonic, extends to over 1metre - $9.50. * CRO TUBES: 1-inch electrostatic deflection type CV1522 on special at $35. * VALVES: 866A $5, 6C6 - $5. * IEC EXTENSION LEAD: 2-metres long - $6. * A 10% discount applies on a 10-off purchase of any one of the above items * All of the items JULY 1992 95 r---------------------- --- , SILICON CHIP BINDERS X Advertising Index Active Media Images ........ ..... .. .. 86 These beautifully-made binders will protect your copies of SILICON CHIP. They feature heavy-board covers and are made from a distinctive 2tone gr~en vinyl that will look great on your bookshelf. Adilam Electronics ..... .. .......... IBC * High quality. * Hold up to 14 issues * 80mm internal width . * SILICON CHIP logo printed in gold- A-One Electronics ................ 74,75 Alpine Technologies ..... .......... ... 90 Altronics ................... ...... ... .. . 60-63 Antique Radio Restorations ... ... 94 Av-Comm ..... .. ...... ................ 67,73 Breakthrough Computers ..... .... . 57 David Reid Electronics ..... ..... ..... . 3 Dick Smith Electronics .... ..... 26-29 EEM Electronics .. ..... ................. 95 coloured lettering on spine & cover. Electronic World ....... .... .. ...... ... .. 89 Yes! Please send me _ ___ SILICON CH IP binder(s) at $A11.95 plus Emona Instruments .. ... .. .... ..... ... 87 $A3 p&p each (NZ $A6 p&p). Geoff Wood Electronics ...... ...... 81 Enclosed is my cheque/money order for $_ _ _ _ or please debit my Harbuch Electronics ............ .. .... 43 o Bankcard Hycal Instruments .. ........ .. .... 71,95 O Visa Card O Master Card Jaycar Electronics ... .......... ... 45-52 Card No. L__L__~I ._I~'------'I I._L__L__c____,I ._I~~ J.V. Tuners .. ... .. .................. ...... . 43 Oatley Electronics ................ 21 ,95 Obiat Pty Ltd ............................ IFC Signature_ _ _ _ _ _ _ _ _ __ Card expiry date_ _-'/_ __ Name _ _ _ _ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ __ PC Computers ........... .... ...... ..... 95 PC Marketplace ..... .. ..... .. .... . 88,91 Pelham .. .... ... .. ........ .. ...... ...... ..... 95 Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ __ __ Peter C. Lacey Services ........... 40 Preston Electronics ........ ...... ..... 86 RCS Radio ........................... ..... 96 SILICON CHIP PUBLICATIONS PO Box 139, Collaroy Beach, NSW 2097, Australia. Phone (02) 979 5644 Fax: (02) 979 6503. L _________________________ J Resurrection Radio .... .... ..... ........ 9 Rod Irving Electronics .. .. .. .... 10-15 Rolec Pty Ltd .. ..... ................. 68,69 Silicon Chip Binders ... .......... 84,96 Star Micronics .......... ................... 5 listed are new, unless otherwise stated. * You can obtain an illustrated "flyer" that gives more information on these products: send stamped SAE. Major cards accepted with phone and fax orders. Certified p&p Australia $5, NZ (airmail) $10. Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone: (02) 579 4985. Fax: (02) 570 7910. CUSTOM MADE AUDIO accessories. High quality filters , dynamic noise reduction, compressors and other hard to find devices made to your requirements. Call David on (02) 327 6285 after 7pm. EMERGENCY LIGHTING KIT: includes inverter/charger plus nicad battery pack. Connection modes: normal plus emergency lighting or emergency only on 96 SILICON CHIP mains failure. Will operate 13W fluorescent tube. $12 plus p&p. Phone (052) 78 8298. Stewart Electronics ....... .... ..... .. . 95 Tecnico Electronics ......... .. .. ... OBC Transformer Rewinds ..... ........... 95 TopCom Communications .... 91,95 RC§ RADIO lPTY lLTD ::a·~ RCS Radio Pty Ltd is the only company that manufactures and sells every PC board and front panel published in SILICON CHIP, ETI & EA. RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Jemal Products, 5 Forge St , Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. MELBOURNE . --+------------+---- 3 Nicole Close, SYDNEY \ __..,__ _ _ _ §uite 1, Ramsgat\ North Bayswater 3153 P.O. Box 664, Bayswater 3153 Telephone: (03) 761 4466 \ Facsimile: (03) 761 4161 Toll Free: (008) 800 482 -<at>, _ _ _ _ _ _ _ _ _ __.__ _ _ _ _ __ 191 Ramsgate Road, Sans Souci 2219 Telephone: (02) 529 2277 Facsimile: (02) 529 5893 \ • Capacitors • Connectors • Fans • Filters • Headers • LEDs • Plugs • Rectifiers • Relays Resistors • SCRs • Triacs • Sockets • Swtiches • Terminal Blocks • Varistors