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Unmanned Aircraft - The Ultimate In Remote Control -= -- $3.95 MAY 1993 NZ $5.50 rs\l Is the mutt next door a problem barker? This project could be the answer to your prayers. It zaps the dog with a retaliatory supersonic high-level tone to cause discomfort & discourage further barking The Micron Sure-Shot Hand Held Desoldering Gun De-Solders 30 Plus Joints a Minute and is Around Half the Cost of the Competition Exclusive to Altronics and authorised dealers in Australia. This stand alone, fully self-contained desoldering tool makes it a breeze to remove components from any PCB. Even double sided, through hole plated boards. All it needs is a squeeze or two on the trigger and the component virtually falls out. Features: • Totally self contained • Light and compact • Anti static tip Fully Self Contained • Easy to use - No External Pumps or • Simple to clean and maintain Paraphernalia to Carry Around • Variable tip temperature Completely Portable: The Sure Shot desoldering tool is totally self contained and plugs directly into a standard 240V AC outlet. Easy to Use: The Sure Shot generates a high speed vacuum every time the trigger is squeezed. This vacuum causes the molten solder to flow into the collection reservoir contained within the unit. Here the molten solder solidifies into small particles. Suitable for all type of P.C.B.'s With its inbuilt variable temperature control the Sure Shot is ideal for single sided, double sided and through hole plated P.C.B.'s. With just a couple of squeezes of the trigger all holes are left solder-free for easy removal of the component Includes Quality Carry Case and Tool Kit. 2 Year Warranty T 1272 1mm Spare Tip to Suit T 1273 1.6mm Spare Tip to Suit T 1275 Pack 10 Filters to Suit ess Delivery Se BANKCARD, VISA OR MASTERCARD HOLDERS Phone Order Free Call 008 999 007 Just phone your order up to 4pm eastern standard time and we deliver next day to every capital city and suburbs, (Country areas please allow additional 24-48 hours). Delivery charge $10.00 14 DAY MONEY BACK SATISFACTION GUARANTEE. If for any reason you are not absolutely d elighted with the quality and performance of the Altronics T 1270 De-Solder Tool you may return it to us for a full refund less transport costs. -~~ ..G ~ 174 Roe St. PERTH. Western Australia. 6000 Phone: (09) 328 1599 O~Iy $349· 00 The Micron Sure Shot is quickly taking Australia by storm. Here are some user comments: "I am very impressed with the T 1270 de-soldering tool. It makes de-soldering easier than soldering." Brett Smith, Brett Smith Technologies Pty. Ltd. QLD "For the Price and what it can do it is the best de-soldering tool on the market.'' Adrian Michell, Television Replacem ents. VIC. "We found the Micron de-soldering gun a must to have. The unit is easy to handle and the desoldering action is very fast." Robert Benden, Qualitec. NSW. "Comparing the performance and price with other brands, it is very good value for money. The carry case makes it handy for the tradesman on the move." Trevor Hewitt, Electro-Acoustics. WA. Authorised Dealers QLD. ECQ Electronics Pty. Ltd . ..... (07) 254 1153 S.A. Force Electronics .... ................ (08) 21 2 5505 Aztronics .. ................ ........ .......(08) 349 6340 Mektronics .. .. .......... .... ............ (08) 346 0333 TAS. George Harvey Hobart ......... (002) 342 233 Geor e Ha.rve Launceston .(003) 316 533 N .S.W. David Reid Electronics ......... (02) 267 1385 Ames Agency ... ............... .. .... .. (02) 319 4525 Vilec Distributors ..... .... ...... .. .(049) 566 808 Novocastrian Elect. Supplies .(049) 562 562 VIC. Television Replacements ..... (03) 850 4144 Mektronics .. ............................ (03) 587 3888 Vo/.6, No.5; May 1993 FEATURES 4 Hifi Review: Dynaudio Image 4 Loudspeakers by Leo Simpson Two-way system can handle 1000W transients REJUVENATE THOSE TIRED nicad cells with this simple project. It will correctly discharge any nicad cell so that it can then be recharged to full capacity - see page 20. 16 The Microsoft Windows Sound System by Darren Yates New software lets you talk to your PC 86 The Story Of Electrical Energy, Pt.23 by Bryan Maher Winning the white metal - the story of aluminium I PROJECTS TO BUILD la W"OOF:ER s •r o J?PBR( i,t;.,,: 'vj ,·.;;~~ .. 20 A Nicad Cell Discharger by John Clarke Build it & rejuvenate those tired nicad cells 26 Build The Woofer Stopper by Darren Yates It zaps barking mutts with a supersonic tone 32 Remote Volume Control For Hifi Systems by John Clarke Adjust your stereo system from your armchair ZAP THAT BARKING DOG next door with the Woofer Stopper. It produces a retaliatory high energy supersonic (20kHz) tone that discourages further barking. Turn to page 26. 64 Alphanumeric LCD Demonstration Board by Darren Yates Plugs into the printer port of your PC 70 A Low-Cost Mini Gas Laser by Flavio Spedalieri Build a laser pointer for $60 SPECIAL COLUMNS 40 Serviceman's Log by the TV Serviceman From little acorns, giant oak trees grow 53 Remote Control by Bob Young Unmanned aircraft - the ultimate in remote control 56 Vintage Radio by John Hill A few old receivers from the 1920s 64 Computer Bits by Joe Elkhorne Upgrading to a 386 - more on kludging a computer THIS TRANSMITTER & its companion receiver will let you adjust the volume & channel balance of your stereo system from the comfort of your armchair. Details page 32. 82 Amateur Radio by Garry Cratt Kenwood's mighty little TH-28A & TH-78A transceivers DEPARTMENTS 2 7 8 70 Publisher's Letter Mailbag Circuit Notebook Product Showcase 84 Back Issues Ask Silicon Chip Notes & Errata Order Form Market Centre 96 Advertising Index 90 92 93 94 BUILD THIS PROJECT & find out how alphanumeric LCD panels work. It interfaces to the printer port of your PC - see page 64. MAY 1993 1 Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) PUBLISHER'S LE'l*I'ER Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates, B.Sc. Reader Services Ann Jenkinson Sharon Macdonald Marketing Manager Sharon Lightner Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman , VK2ZLZ John Hill Jim Lawler, MTETIA Br-yan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications 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. This month, we have a range of interesting projects for readers to build but two are especially noteworthy. The first is the "Woofer Stopper" which may have a whimsical name but it is intended to help solve the very common problem of barking dogs. It is a great pity that so many people are bothered by barking dogs, particularly as the dog owners either are oblivious to the problem or deny that their little darlings ever bark. As presented, the "Woofer Stopper" can be very effective against dogs that are close to your home, say within 20 or 30 metres. In that situation, it can work like a charm and without the offending dog owner even knowing that you have taken action. On the other hand, the "Woofer Stopper" is a partial solution to what is really a sociological problem. In the long term, I hope that people and municipal councils will come to recognise that unless dogs are properly disciplined and are not left alone for long periods every day, they do become a nuisance. Subscription rates: $42 per year in Australia. For overseas rates, see the subscription page in this issue. Our second project which is worthy of note is the "Remote Volume Control" which is based on a 68HC 705C8P microprocessor. At first sight, this may seem like a complicated alternative to the remote controlled motor-driven volume controls now seen in many domestic hifi systems. However, it solves the problems of having to obtain special volume and balance pots and is a superior solution as far as performance is concerned. It also represents a step forward for us in that we can now present dedicated microprocessor projects and we will be supplying the programmed microprocessors to kit sellers and individual readers. · 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. And finally, we have some news of an even bigger step forward . In the near future, SILICON CHIP will be published in the United States and Canada. Gernsback Publications, Inc of New York, who presently publish Popular Electronics and Electronics Now (formerly Radio Electronics), will initially be publishing four issues a year of SILICON CHIP and most of the editorial will be reprodllced from Australian issues. 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. Naturally, we are delighted to he able to announce this development, as it will give us a boost both locally and overseas. To our knowledge, it is the first time an Australian magazine, technical or otherwise, has been licensed for publication in the USA. Printing: Magazine Printers Ply Ltd, Alexandria, NSW; Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. ISSN 1030-2662 2 SILICON CHIP To Be Published In The USA SILICON CHIP Leo Simpson LABTECH 20MHz Dual Trace OSCILLOSCOPE Includes 2 probes VARTA •AA• Nicad Battery * Totally self contained 1.2V * Light and compact * Anti static tip * Easy to use * Simple to clean Due to size and weight, we can not offer free frieght. Please call for a quote on frieght charges. ETHERNET CABLES - BNC M/M 50 ohm 2 mtr. $7.95 3 mtr. $8.95 5 mtr. $10.95 10mtr. $16.95 20mtr. $24.95 T-8 $14.50 T-10 $14.50 a madB In USA 2 way AUTO Parrallel Switch Box For two PC's - one Printer Self powered. $ 59_95 $7.95 $3.35 $3.90 Replacement Tip to suit: $19.95 Replacement Filters to suit: $5.95 PLCC EXTRACTOR Only $9.50 This inexpensive device, which connects direct to your answering machine will automatically disconnect your answering machine whenever ANY PHONE is answered. If your answering machine answers your call before you do, simply pick up any phone, your answering machine will immediately disconnect and you can speak without interference. €}: ~- Vivitar. VEC-1 ',/ic:le:e> Pre>c.e:.s.se>r A video processor that includes Sound mixer, Video mixer (fades), process contrast and colours, also allows picture and negative effects. G#f prlJflGGIIJIIII r 1g11/tG, y1t GIJ IIGy tlJ IIGI I Expect to pay $349.00 elsewhere. Now only $319.00 $39.00 James Hardie - Answering Machine - AM100 RF Transmitter & Receiver Remotely control just about any device up to 10-15 meters away. Complete with two key transmitters and one receiver. N.0./N.C. contacts (240V <at> 1A) 12V DC operation on receiver. }:·•"-"-i i i ~ Complete with Deluxe carry case, Tool kit and replacement filters. :Message Stopper TORX Drivers by VACO BNC "T" Joiner Terminator 600mAhr. Computer Keyboard Seal - suit AT101 key Fits like a second skin and remains in place during keyboard use. * Variable tip temperature * High speed vacuum Now Only $650.00 inc. tax. <at> Now only $2.95 * Single Micro-Cassette * Remote Message Access * Voice Activated Recording * Call Screening Only$89.95 * 12 Months Warranty only $89.00 Electronic Projects for GUITAR A book containing projects such as Effects, Pre-Amp's, DI Box, & more. Only $21. 50 **** ATTENTION ALL SMALL - MEDIUM SIZED BUSINESS OPERATORS **** Thinking ofbuying aso called 'lax switch' l Hugie-011-llold DO IT RIGHT THE FIRST TIME ! IT'S YOUR $$$ AT RISK ! How it works:- for single telephone lines. Yes ! It's finally here ! A Music-on-Hold system for standard telephones. No need to purchase expensive PABX or Commander systems, Te lecom installations, etc. Save your hard earned dollars ! Now you can give your customers a relaxed atmosphere while they are on hold. It could also give you the opportunity to promote your products if connected to a Digital Voice Recorder or an endless loop tape via a standard tape player. Utilise your advertising lime and expense every time you put your customer "on-hold". ,- ~~ii -~J!1~:S1'{~~lC;.r., The user can press/ dial 8 (Tone or Pulse) and then hang-up within 6 seconds to put incoming or outgoing call on hold. Call will remain on hold Made in US.A. until the telephone handset is picked up. It's that simple. <at> Note: Calls can only be put on hold or retrieved from hold with the telephone connected to the The Most Advanced Phone-Fax Line Sharer Music-on-Hold. When used with more than one Now Available in Australia telephone extension, the Music-on-Hold line sharer should be installed direct onto the incoming IGi'" NO Confusing Voice Messages line of the first telephone socket. IGi'" NO Delays or Periods of Silence iw NO Unusual Dial Tones System Optlons:iw NO Frustrated Callers E:3=.A.S"V" c::;c:,r-.1r-.1E=c::;I Music-on-Hold Line Sharer $279.00 Music-on-Hold Including Line Isolation Unit $359.00 Austel Approved. If you need more information on this product, please call Jeffery Yager on (02) 267 1385, or by fax (02) 261 8905. A fop product for '93. Austel Approved. ~ Installs in minutes on ANY PHONE SOCKET. Total Flexibility. Will even operate with a Modem. Free information sheets available. 2 year exchange warranty, full product supporf. Dynaudio Image 4 2-way loudspeakers The Dynaudio Image 4 is a large tower speaker with just two drivers, a 28mm tweeter & a 20cm woofer with bass reflex loading. It is rated to handle amplifiers up to 180 watts per channel & has a very smooth frequency response. By LEO SIMPSON Large 2-way loudspeakers are relatively unusual. The trend is for larger speakers to have three, four or even more drivers. This is sometimes done deliberately so that buyers feel that they are getting more value for their money but it does not necessarily result in better sound. The design philosophy behind the Dynaudio Image 4s is that more is not better. Many loudspeaker systems on the market do not have any useful bass response below 50Hz so these Dynaudio Image 4 loudpeakers are unusual in this respect too. They have a very smooth response which extends down to below 30Hz - almost a full octave below 50Hz. The difference that can make is sensational. But why go to a tower loudspeaker. The overwhelming fashion among loudspeaker designers today is to produce small 2-way systems which have to be mounted on stands if they are to give the best performance. The stand brings the tweeter up to about the ear level of the seated listener and thereby ensures that he or she is sitting almost "on axis" with the tweeter. Thus, the listener gets to hear ·every little nu- This cross-section of the Dynaudio 24-W-100 shows its unusual construction. The voice coil is 100mm in diameter and the circular magnet is ventilated to prevent pressure build-up under the large dust cap. The inside-out construction of the magnet means that flux leakage is low & the speakers can be used close to TV monitors. 4 SILICON CHIP ance produced by the tweeter. Although small loudspeakers can also conveniently sit on a bookshelf, they usually don't give the best results in this position because they are too close to the walls or corners of the room. This tends to muddy the bass and lower midrange. So it is back to having stands for the best results. Now while having small speakers on stands is necessary if they are to produce their best, it also means that they occupy more floor space than their small size would indicate. The stands inevitably must be quite heavy and their "foot print" is quite large to avoid having them easily tipped over. Thus, the typical loudspeaker stand has a footprint which is 25 to 30cm wide and 30 to 35cm deep. With the above factors in mind, a tower loudspeaker starts to make a great deal of sense. It doesn't occupy a lot of floor space and it doesn't need a stand since it is already tall. The tower concept also means that the designer can settle for a much larger enclosure and thus obtain a much better bass response than would be possible - all other things being equal. The trouble is, some tower speakers don't look attractive at all. However, by any normal standards, the Dynaudio Image 4s are impressive to look at. The designers have managed to design a large loudspeaker without producing one that dominates a room. As a tower speaker, it is quite tall at 950mm high but its width of 270mm and its depth of 325mm means that it occupies no more floor-space than typical bookshelf sty le speakers mounted on stands·. A contributing factor to its grace rather than gross is that the grille cloth frame does not cover entire front of the cabinet, leaving more than a third of the veneered panel visible. I should state at the outset that the Image 4s are available in two genuine timber veneer finishes: black Ash and Mahogany. This reddish timber is somewhat lighter than the Rosewood which used to be a popular furniture finish many years ago. In this reviewer's opinion, the Mahogany finish is a delightful contrast to the dreary black of today's speakers. Removing the grille cloth frame reveals that the Image 4s are simply a 2way bass reflex design with a 28mm soft dome tweeter and 200mm (8-inch) woofer with a polypropylene cone and foam rubber roll surround. -However, there is far more to it than that because both drivers turn out to be "specials", produced to meet the requirements of the Australian design team, Glen Leembruggen and David Connor. The immediately noticeable feature of the woofer is its very large dust cap. That conceals a voice coil which is 100mm in diameter. This must be a record for virtually any loudspeaker driver. The upshot is that the voice coil can dissipate very large amounts of power without becoming excessively hot and this means that "dynamic compression" is greatly reduced. In conventional loud~peakers, high power dissipation causes the voice coil resistance to rise and thus the speakers do not respond linearly to loud signals - they are compressed. Dynaudio claim that the 24-W-100 woofer used in the Image 4s will faithfully reproduce a 1000 watt 10 millisecond transient. If that sounds remarkable, they make the same claim for the matching D-28-AF tweeter! On the rear panel, the Image 4 has a recessed terminal panel with large gold-plated binding posts which can take really massive loudspeaker cables or banana plugs. Furthermore, there are two pairs of terminals which are normally connected in parallel with gold plated straps. With the straps removed, you have the option of bi-wiring or bi-amping. Personally, I cannot see the point of bi-wiring. In. effect, you use separate pairs of leads to power the tweeter and woofer and thereby supposedly reduce any interaction between high and low frequency signals as they pass along the cable. To anyone with a knowledge of AC circuit theory, and Pictured are two units in the Dynaudio Image range: the large Image 4s (right), subject of this review, & the Image 3 which uses the same D-28-AF tweeter. more particularly the Superposition theorem, this is rubbish. Note that whether you elect to "biwire" or "bi-amp" your loudspeakers, the normal crossover components remain in place. In addition, a bi-amp system (ie, two separate power amplifiers in each channel) requires an electronic crossover and its inevitable phase shifts at the crossover frequency will be added to those already produced by the loudspeaker's own filter network. These additional variances cannot be allowed for by the designers and therefore the results will not be as good as if the speaker was used in the conventional fashion. Some reviewers have argued that bi-wiring means less voltage drop for the signals to the tweeter and woofer but even that is not true, although it would take rriore space than can be spared to prove this argument. To me, the only reason for includ- ing the bi-wiring facility is to satisfy the hifi faddists, those golden eared types who hear an improvement after every fiddle and tweak. Whether or not you agree with the idea of bi-wiring, bi-amping or other gimmicks, the connecting terminals for these Image 4s are beauties and they should be a feature of any loudspeaker that claims high performance -you really do need them if you are to use heavy speaker cables and thereby obtain the best sound quality. Lest any reader think that I am against heavy speaker cables, let me reassure you on that score. I believe that the lower the resistance of the speaker cables, the better. Again, I don't have space to go into the reasons why and nor are they the ones necessarily espoused in hifi magazines. The highest quality components have also been used in the crossover filters (air-cored inductors, etc). The MAY 1993 5 These scope photos show the enormous power handling capability & dynamic range that these speakers have. They can reproduce a 1000 watt transient with no dynamic compression. crossover network is a third order Chebyshev filter for the tweeter and a 6dB/octave filter for the woofer. The crossover frequency is 2.5kHz. By the way, the Image 4 is specified as having a nominal impedance of 6 ohms. The minimum impedance is 4 ohms and occurs at just under 3kHz. On a practical note, the Image 4s are unwieldy to lift and move about. While they are not particularly heavy at around 27kg, there is nowhere to grasp them. The baffle is completely flush when the grille is removed. In facr, I resorted to lifting them by putting one hand inside the port there is no other practical hand hold. Listening tests As noted above , relatively few loudspeakers have a response extending below 50Hz and those that go below 30Hz are rare indeed. The Image 4s have a frequency response quoted at 36Hz to 25kHz within ±3dB. That is exceptional enough in itself but it also means that the usable bass in a typical living room can be expected to be below 30Hz. Our listening tests on constant sinewaves indicate that the Image 4s do have a very smooth and extended frequency response right up to the limit of audibility and yes, it really is usable down to below 30Hz, with very little tendency to frequency doubling (ie, tending to second harmonic distortion) at moderate power levels. In other words, the bass is very clean and when compared to many other largish speakers, quite restrained. For its part, the tweeter is exceptionally smooth and the crossover does its work well, with little sign of "suckouf' or phasing problems. The cabi6 SILICON CHIP net is also commendably "dead" and panel resonances are well muted. So how do they sound on music. To some ears, on orchestral music, the treble may sound a little bright but extended listening indicates that it is more a matter of clarity of reproduction than a matter of a bright response. Stringed instruments are very well produced and the stereo imaging from a pair of these speakers is very sharp (hence the name "Image"?) On normal instrumental music it cannot be said that the bass response of the Image 4s seems notable. As noted above, it is quite restrained, a sign that there is little bass distortion. It is only when you play classical organ or piano pieces that it really shows its stuff. The dynamics of a concert grand piano are rarely reproduced by any hifi system regardless of its cost. Consider that the lowest note on a piano is A, four octaves below A 440Hz. That means its fundamental frequency is 27.5I-Iz. Consider also that the piano has the largest dynamic range of any instrument in the orchestra and you begin to get some idea of how difficult it is to reproduce. In fact, the full bottom octave of the piano is not reproduced at all, on fundamentals, by many bookshelf speakers which have a bass cut-off at 70Hz or higher. Hence, on paper the Image 4s should be well suited to piano works and indeed they are. As one who is exposed to a great deal of piano music (from a Yamaha U1A) played by my daughters, I can state that I have never heard a loudspeaker give a more realistic rendition of the piano. The growl of those bass strings together with the big sounding board is really there. You can hear the damper action clearly and even the squeak of pedals or the pianist's stool on some tracks - very impressive. On drums, whether played in an orchestra or a jazz combo, the Image 4s are startling - ·you will not hear deeper bass unless it is from the real thing. These speakers are what some hifi enthusiasts call "fast". Their attack on transients is what makes their reproduction of piano, drums and percussion instruments so good. It almost goes without saying that the rendition of classical organ pieces is a delight to hear, and feel. Again, they can seem quite subdued in the bass when compared with other large loudspeakers but when they "speak" they are clearly heard. For a speaker with such an extended bass, you might expect it to be a little "chesty" on male voice but it is quite natural. No problems on that score at all. Efficiency of the Image 4s is about average at 90dB/1 W/lm and to get the best out of them you need an amplifier capable of at least 100 watts per channel into 4-ohm loads. The manufacturer specifies their power handling at up to 180 watts but I would go further and state that they should comfortably handle the output of a 200 to · 250 watt per channel amplifier on normal program material. Conclusion By any normal standard, this must be rated as a rave review. In my listening room which has cement rendered walls, slate over a concrete floor with rugs and plenty of bookshelves to give a room sound which is about right (not too bright), these speakers gave an exceptional account of themselves - I have not heard better, even from speakers costing many times more. There, I've really gone and said it. But the Dynaudio Image 4s are not cheap and are well out of the range of most enthusiasts. Their recommended retail price is $2.490 a pair and they have a 5-year warranty. However, if you can afford them they will give far more satisfaction than other speakers costing many times the price. If you cannot afford them, have a listen to the lower priced units in the range which start from $690 a pair. For further information, contact Scan Audio Pty Ltd, 52 Crown St, Richmond, Vic 3121. Phone (03) 429 2199. SC MAILBAG Home security with a CCTV system Your article on the Alarm-Triggered Security Camera in the March 1993 issue of SILICON CHIP prompts me to write about a Neighbourhood Watch type idea that floats to the top of the mind from time to time. As you are aware, break and enters are one of the great scourges of modern living. My idea is that a household should use the ubiquitous VCR, hooked up to simple video cameras as a recording surveillance system, so that would-be criminals can be identified as they check out what is easy to get into around the suburb. I envisage a system where there are hidden cameras positioned to see who comes to the front and back doors and whatever other points you want to cover. The cameras record to the VCR an d, to make a tape last a weekend or longer, only take a shot every few seconds or whenever movement is detected. Systems such as I describe are commercially available but for prices of several thousand dollars. I would assume that nowadays all the necessary parts for a surveillance recording system are available quite cheaply. It just (just?) requires the know-how of SILICON CHIP magazine to identify the components and work out how to put them together. I know someone is going to say "You aren't going to help the police mu ch when they steal the VCR" . That is quite right but the idea is based on the known facts (check with your local Neighbourhood Watch) that most break and enters are crimes of opportunity performed by lazy people who are not terribly clever. These people do not break into every dwelling they approach; instead, they go arou nd the suburb looking for an easy mark. Someone is also going to say "Isn't it a bit of a long shot installing one of these systems and hoping to film criminals?" I don't think so. With the number of break and enters that there are, especially in the inner suburbs, it is quite probable your dwelling is oc- SILICON CHIP, PO Box 139, Collaroy Beach 2097. casionally examined as a potential target. So there is my idea. If the device can be made for a low enough price, and enough of them are installed out in the suburbs, the house breakers will soon realise they are being caught a lot more often and give housebreaking away as being too risky, enabling us to live in peace once again. Robert Ward, Yeronga, Qld. least half those mentioned in your article. You guessed it, I'm blowing my own horn and those like me who offer a service of monitor repairs for $100.00, or $150.00 for some monitors requiring expensive parts. For customer oriented small businesses like mine, $200.00 for a 5-cent resistor is definitely not on. Eli Montebello, MTETIA, EEM Electronics, Epping, Vic. Comments on computer monitor reliability More on computer monitor reliability I have a comment regarding the letter from R. Pankiv of Sheffield, Tasmania, on page 11 of the March 1993 issue, requesting more information on appliance servicing. I suggest that he contact Jim Lawler with a view to becoming a member of the Electronic Technicians Institute, Tasmania Division of which Jim is the Secretary. Jim Lawler's address is 16 Adina St, Geilston Bay, 7015. I feel that this would best satisfy Mr Pankiv's need for servicing information of all sorts. This does, of course, assume that Mr Pankiv is a qualified technician. On the subject of the Publisher's Letter in the March 1993 issue, I do agree that the computer monitor is one of the least reliable components of a computer system; second would be the more unstable or poorer quality motherboards. I would also agree that the majority of faults occur in the power supply and deflection circuit. What I don't agree with is your assessment of the computer monitor service industry. In your letter you outline two types of repair agent, large companies who charge a fortune for either board replacement or component level repair. What about us, the third type of company that you chose not to outline in your article: those businesses that work tirelessly in an effort not to write the unit off so that the customer does not need to spend extra money on a new monitor; those businesses who offer fixed price servicing of computer monitors with prices that are at I read with interest your editorial in the March issue about the lack of reliability of computer monitors. This problem is becoming particularly noticeable with the increase in the reli ability of other computer components. Many modem manufacturers are now offering 2-year warranties, with some offering up to five years (Telebit, ZyXel, AT&T) . Hard drive manufacturers also now routinely offer 2-year warranties, often with a small extra fee for a 5-year warranty (similar to the extended warranties that were offered on colour TVs not so long ago). Traditionally, the lifetime for a hard drive is 2-3 years, so · we're going to have to re-evaluate our expectations. It is becoming rare to see a computer come back for servicing within two years of its initial sale. Often they will run for 6-8 years without any problems at all - except for the monitors! In fact, most computers come back for hardware upgrades. On the subject of board level repairs, monitor manufacturers aren't the only ones with this policy - Apple does this with the Macintosh, with a fixed service fee for a Mac Hex. About the only way I know of reliably getting manuals as a consumer is to make the supply of a service manual a condition of sale. However, at least one university I know of with the same policy has consistent problems with it not being enforced, with attendant hassles for the technicians when the equipment inevitably fails. A. Brown, Palmerston North, NZ. MAY 1993 7 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. Interface for the LCD panel meter +9·12V + 10 16VW+ While the LCD panel meter published in the September 1992 issue has proved popular, a problem arises if you want to power it from the same circuit you are monitoring. To operate correctly, the 7106's differential inputs must range between about lV above ground and 0.5V below pin 1, the meter's positive supply. This is a problem when you power the meter from the same supply that you are monitoring , because the IN LO pin then needs to sit at 0V. This circuit gets around this problem by using an LM358 op amp to drive the INHI input. The non-inverting input of the op amp is biased from the REFLO pin, which is tied to INLO and COMMON as in the original circuit. The differential inputs of the op amp can then be pulled high or low and provided the gain is such that the meter does not overrange, the inputs of the 7106 will always be within the correct voltage range. The gain for the circuit is set so that the largest voltage to be measured will give an output of 2V above the bias voltage. For example, a 0-20V range will need a 10:1 divider or a gain of 0.1. Setting Rx to lO0kQ and Ry to lOkQ will give this gain. Similarly, for a 0-200V range, a 100:1 ratio is achieved if Rx= lO0kQ and Ry = lkQ. Current measurements are made by simply connecting the differential inputs across a sensing resistor and setting the gain accordingly. To measure up to 2A, use a sensing resistor of 0. lQ. This will have 200m V across it when 2A flows through it. Selecting a gain of 10 will then Seven day hose controller This timer was designed to meet the watering restrictions current in Brisbane. These allow watering times in 4-hour blocks on three days a week, with no hoses allowed from 10am2pm. Since the watering times are based on 4-hourly blocks, the timing circuit based on IC1-IC4 produces a high pulse at pins 6, 9 & 10 of IC4 every four hours. ICl, a 14-bit binary counter, is cascaded with IC2, a 12-bit binary counter. The clock signal for ICl is obtained from the power transformer's secondary via a resistive voltage divider clamped by ZDl, a lOV zener diode. 8 SILICON CHIP 15k 0.1 10k 35 RV 32 REF LO COMMON +9·12V +SENSE 31 -SENSE IN HI 3o IN LO 33 CREF RV 7106 0,1 38 osc 3 39 osc 2 osc 1 100pF 100k 40 29 AUTO ZERO 0.47 47k 28 BUFF 37 TEST 21 BP 0,22 27 INT give the correct reading on the liquid crystal display. Phil Angilley, Brookvale, NSW. ($20) To provide the required 4-hour long pulses, IC3 (a triple 3-input NAND gate) is combined with IC4 (a 4025 triple 3-input NOR gate) to provide a 9-input AND gate function. The 4-hour pulse output from pin 10 ofIC4 is coupled to the clock input of IC5, a 4017 decade counter and 1-of-10 decoder. The six used outputs of IC5 each go high in turn for four hours, corresponding t,o a 24-hour period in total. The 7th output, Q6, goes high after 24 hours and is used to clock IC6, a 4017 used as a 7-day counter. Q6 of IC5 also provides the reset to pin 15 via diode D8. Each of IC6 's seven used outputs goes high for one day. The 8th output of IC6, Q7, provides the reset to pin 15 via diode D9. The selected 4-hour output from IC5 and the selected day output from IC6 are ORed via the respective diodes and fed to transistor Ql which drives relay RLYl, a 12V subminiature type from Dick Smith Electronics (Cat. S-7112). This applies 24VAC power to the hose solenoid from the power transformer. The -.0lµF 3kV ceramic capacitor across the bridge rectifier (Dl-D4) suppresses turn-off transients from the solenoid which would otherwise cause premature resetting of ICl and IC2. The water solenoid used in the prototype was obtained from Goyen Controls, part number ST2-6/1361, and cost $32 .70. John Holliday, Nathan, Qld. ($50) ~ ~ co co w ..... > -< AC1 +V1 .,. .,. 240:JI ov RL Y1 .:..--, OFF_ I 47k :S:: 1M:S:: I I .,. I .,. .01I ZD1 10V 0.1: .,. 10k ~ 10k RS '- I sou .,. IC2 4040 16 .,. }gio 16 I I I • AC1 I 2 as Q3 5 7 01 011 1 2 012 3 a13 13 07 15 010 HOSE SOLENOID I Rs I 111 ~CK 11 10 CK ___I 0.1! J. 2 1 13 12 11 9 10 J. 0.1+ .,. 1000 25VW+ + .,. 0.1+ I I I I +V2 .,. ~ J. 0.1+ 100 ii 16VW+ I I 0.1 47k 7 .,. cL 47k! +V1 1~9~4 10 0,,1 J. 0.1+ as 6 ? 07 4 2 3 0.1+ 1 -t 1 +V1 D10-D15 6x1N914 S3 8-DIL B I I 6AM-10AM SAT FRI THU WED TUE MON SUN 12k .,. 2AM·6AM 10PM-2AM 6PM•10PM 2PM-6PM 10AM-2PM .,. This hose controller allows the user to select watering times in multiple 4-hour blocks on selected days of the week. Q6 5 as Q4 10 Q3 7 02 01 15 RS IC6 4017 ao 16 +V1 04 10 Q3 7 Q2 4 _r31f IC5 4017 3 Q1 2 ao 14 CK I Q6 14 CK 15 RS 16 I .,. +V2 SOFTWARE REVIEW TALK TO YOUR PC with the Microsoft Windows Sound System I MAGINE BEING able to throw away your mouse and keyboard and op erate Windows and any Windows applications by just speaking the commands . into a microphone. Sounds pretty good, doesn't it? This ideal is a little way off yet but Microsoft has just released the first low-cost practical sound interface system designed for serious applications. But it's much more than just a digital audio recorde.r or a voice command translator. It's a complete audio system designed to enhance and support business reports and displays. So when we were offered the chance to take a look at Microsoft's latest package, we jumped at it! As we see it, audio command input or voice recognition will be a significant step forward in computer evolution. The opportunities and applications are endless - from automatic teller machines, to desktop publishing, to medical work, to industrial control. It will also be a great step forward for the disabled, enabling them to take part in careers that would otherwise be a whole lot more difficult. And it will make computers more accessible to the general public , reducing some of the "fear" that prevents many from using them. Keyboards and buttons will be replaced by just a microphone, making computers easy to use. The Microsoft Windows Sound System comes with a sound card (with an Analog Devices' DSP chip on board), a pair of headphones, a microphone, a set of floppy discs and a comprehensive manual. The card is a 16-bit device so you'll 16 SILICON CHIP The Microsoft Windows Sound System marks a breakthrough. It can record CD quality sound, add sound to business presentations, and control many Windows applications. By DARREN YATES need a spare 16-bit slot. There are two RCA line out sockets and several stereo 3.5mm sockets which serve as audio inputs and outputs. If you don't like wearing headphones , you can connect a couple of small un-powered or powered mini speakers to the headphone socket. So being calm, methodical and following the normal rules, we lunged straight for the discs and loaded the program in. However, Microsoft has apparently realised that few people bother to look at the manual at this stage. We say that because once the program has been loaded, the initial screen talks about installing the board - which isn't a bad idea! Installing the program Installation of the program is as simple as loading the first disc into ~ocabulary For: Definitions: OK Cancel Left Right Up Down Help New Open Move Copy {Enter} {EscHEsc} {Left} {Right} {Up} {Down} {Fl} N 0 M C The Vocabulary utility lists the voice commands used in a particular application, in this case for Program Manager. The buttons down the righthand side allow new words to be entered & edited as required. the drive and running the setup program under Windows. The Windows Sound System program then takes over. It even explains the options when configuring the board, so that it doesn't interfere with other external devices such as hard drives and modems , etc. Windows creates its own program group for the Sound System software and this has eight icons - Volume Control, Recording Control, Sound Finder, Music Box, Windows Sound System Setup, Quick Recorder, Voice Pilot and Guided Tour. And, of course, there's a comprehensive help menu as well. If you're not into reading manuals but want to learn about the program in the shortest time possible, then the guided tour is your best bet (but put the headphones on first). It takes you through each of the applications with simulated on-screen windows, as well as giving you examples of what to expect through the headphones. It doesn't take you through every possible option but it will give you a good idea of what to expect from the program. Volume Control The Volume Control option lets you set up the volume and balance to the outputs and headphones. In the expanded view, it also sets up the audio mix from the microphone and audio inputs, as well as from a sound file already in your machine. Recording Control The recording control is slightly different in that it sets the source, either line-in or microphone input, as well as the input level and balance when you record. Note that the Sound System records in stereo with the line input but in mono with the microphone. Sound Finder This is the first of the major applications. Once you click onto the Sound Finder icon, the system displays a list of the sound files that come with the Windows Sound System. You can load and play any one of these files using the menu and execution keys down the righthand side of the screen. The Windows Sound System supplies 52 sound files which include music samples, birds, elephants, clapping, industrial tools - just about The Windows Sound System package comes complete with a sound adapter card, a microphone, a pair of lightweight headphones, a comprehensive instruction manual & either 3½-inch or 5¼-inch floppy discs. An on-screen guided tour guides the system setup & teaches the basics to get you started. everything you could imagine (except a 38-class loco climbing a steep grade). For example, you can load a file called CHIME3.WAV (all Sound System sound files have the extension .WAV). Click on the PLAY button and you'll hear the sound of wind chimes. You can stop it at any time, adjust the volume and edit the sound file. Each sound file can also be given a special icon which describes the sound. This can be changed at any time. There is also room to give a written description of the sound file to say what it is, who recorded it or whatever. There is also a Properties menu which shows you the sampling rate and size of a particular sound file that has been recorded. Quick Recorder This is where you create your own masterpieces. The Quick Recorder comes in two modes : (1) a reduced screen graphic which displays the basic record, play and stop functions, the name of the file , its duration and the current recording position (we'll talk more about this in a moment); and (2) an expanded view which gives you an editing window as well. This displays an approximated waveform of your sound file. You can think of it as an oscilloscope which can display the whole file on screen at once! MAY 1993 17 front and pasting them on the back. Mixing a number of waveforms together is also possible and this is done using the PASTE MIX option from the EDIT menu. You can select any portion of a waveform and mix it at any point with an existing sound file (this can be done repeatedly). By the way, we ran the Windows Sound System on a 25MHz 386 with a co-processor and found that if you push the system to its Hmits ( ie, record stereo CD quality with all the memory you have), the machine runs out of speed Quick Recorder displays the waveform for a selected file (in this case, Dazza.wav). It on replay. By this, we allows you to cut .& paste sections of the waveform to change the word order & to add in or mean that the sound is mix various sound effects (eg, echo, fade, speed, & base & treble filtering). - replayed in "chunks" as To start off, you click on the file sample determine the overall sound the program processes the next piece option, and select NEW. Quick Re- quality, with higher numbers in both of audio to be sent to the output. This corder will then ask you to pick a parameters producing superior record- is where the Pentium® (the successor sampling rate as well as the number ings. Once you've selected these pa- to the 486) would come in very handy. rameters, you then click on the of bits taken per sample. You have three choices of sampling RECORD button and away you go. The Proof Reader rate: radio (1 lkHz), tape (22kHz), or computer will then record the in put If you're using Microsoft Excel or CD (44kHz) quality. There are also until either you press the STOP but- Lotus 1-2-3 from Windows , you can three choices for compression: com- ton or you run out of memory, which use the Windows Sound System to ever is first. pressed (4 bits per sample), normal (8 verify your numbers and text as you The computer will then, after chew- load them in. bits) and high fidelity (16 bits). These also determine how long your ing over the data, display a waveform You can also load in your own dicrecordings will be. For example, if on the screen which simulates your tionary and Sound System will use this to check your documents. The you choose CD quality sampling at input. the high fidelity compression, you'll There are various effects which can speed at which it reads as well as the now be applied to the recording and direction can all be set or customised chew up 88Kb of RAM per second. And that's only for mono sound. If these are accessible through the EF- to suit your particular application. you want to record stereo CD quality; FECTS menu. These effects include it becomes 176Kb per second. Over a fading up and down, varying the speed Voice Pilot period of 30 seconds, this works out in 25% increments, adding in echoes The Voice Pilot section was the most (such as auditorium, closet and can- interesting feature of the package. It to be well over 2.5Mb of RAM just for mono sound. The sound quality will yon), filtering out treble or bass, and allows you to speak commands into trimming the sound file to remove the computer rather than having to be great but not for very long. silent portions. If you take the lowest quality opclick a mouse or punch a keyboard. This last effect is useful if you wish tions, 2.5Mb will give you about eight The main problem with voice recminutes of recording time in mono to include as much information as ognition systems in the past has been possible for a given memory space. and four minutes in stereo. the ability to recognise the same word being said by any number of people. Editing Digital recording Even though it is easy for you and I to You can also use the editing windistinguish the way different people The way Sound System records is similar to a DAT recorder. It turns the dow to remove unwanted glitches in say the same word, this is a much a recording or to remove whole harder task for electronics to achieve. audio signal into a sequence of digital numbers which represent the instan- phrases. The variation in the waveforms of taneous volume of the signal at a parSections of the sound file can be two people saying the same word will ticular. point in time. cut and pasted to another part of the be too great for the computer to recog· These numbers can then be stored file . For example, the phrase "the cat nise easily. and later transformed back into the sat on the mat" can be edited to sound To get around this problem, Microoriginal audio image. Both the sam- "on the mat the cat sat" by simply soft has come up with a simple alterpling rate and the number of bits per cutting the first three words from the native. Seeing that it is only going to 18 S1L1CO N CHIP be a few people who use any one particular machine, it would be simpler to carry a "catalog" of their voice patterns for the command words and to compare the inputs with these catalogued words. However, since a different inflection in one's voice creates what the computer would call a different waveform for the same word, a database of three samples is kept for each word per person. Any number of users can be kept on the database, provided you have enough memory to hold their voice commands. Editing a user's voice database is easy and adding new commands to run new applications is not difficult. The Voice Pilot can be used on a fair range of Windows applications programs, including Aldus PageMaker, WordPerfect for Windows and most of the Microsoft range of Windows application programs. As you can imagine, all this audio processing to carry out commands does slow the machine right down to the point where you may start to think that it would have been quicker to use the mouse in the first place. The point here is that if you want to use this part of the Sound System seriously and speed is very important, you'll need a 486DX at least. Application audio If you're using Microsoft Excel for Windows or Lotus 1-2-3 for Windows, you can also take advantage of Sound System's business audio to enhance you business presentations . Using Sound System, you can click and drag the cassette icon which represents your audio file into your application and have it play the file directly on cue. Event-driven sound Another application of the Sound System software is using it to produce sounds to suit particular events. For example, say you have a PC that is a central machine in ·the office. Everyone comes to this maGhine to download or pick up files that are then worked on elsewhere. A user then comes by and selects a file to delete from the machine. The Sound System can be made to play a message which says, "Do you really want to delete this file, Harry?". You can assign a sound file to just 009theme.wav 01 Otheme. wav 070tHeme.wav 254theme.wav ahhh.wav applause. l'lav belll.wav bell2.wav I I )1 Reserved, Library of ds, Cornell Laboratory of Ornithology, It The Windows Sound System comes with 52 pre-recorded sound files, including music samples, birds, elephants & industrial tools. The Sound Finder utility lists these files plus any files you have recorded & lets you play them back. about any event that can be detected, including questions, exclamations and asterisks that Windows generates upon entering a command. SoundScapes Most screen savers look OK for a while but then become boring. SoundScape is the aural equivalent and gives you the chance to generate your own sound environment whenever the computer becomes inactive after a set period of time. Sound System already has a number of SoundScapes built-in, including Birds and Jungle. If the computer has not been used for a certain time, the screen goes black and the Sound Sys- The Volume Control menu allows you to mix three sound sources together, as well as adjust volume & balance. Also featured is .a Mute facility. tern fires up and begins playing the sound files. There are about six different bird sounds which are then played at random times, as well as being spaced randomly in the stereo image. Some sounds will appear in the right channel, others in the left, and others as a mixture of the two. Music Box Finally, no sound system would be complete without a CD-ROM interface. You can program the number of tracks and the order in which they are to be played, and even store your favourite CD song lists on your hard disc. Impressions By now, you will not be surprised to learn that we think that the Windows Sound System is a real breakthrough. A sound package of this quality has qeen a long time in the making and will introduce many to the next stage of computing to hit the market. One of its best features is its price. At only $425, the Sound System is one of the lowest priced serious sound cards on the market. If you're looking for a sound card that does more than just make pretty sounds for games, then this is the one to go for. SC MAY 1993 19 Get maximum life & capacity from your nicad cells Build this nicadcell discharger Are you having problems with nicad cells in your battery packs? This low-cost discharger will avoid most of those hassles. It will correctly discharge any nicad cell so that it can be recharged to full capacity. Design by JOHN CLARKE Back in July 1992, we published a simple but effective nicad battery discharger for battery packs ranging from 6V to 12V. This has proved immensely popular and so has a more complicated automatic discharger design featured in the November 1992 issue of SILICON CHIP. The latter design was able to discharge battery packs ranging from 3.6V to 12V. As good a:s these designs are, they do suffer from one major problem. Ideally, to obtain maximum capacity from a nicad battery pack, each cell should be separately discharged to the "end point" voltage of 1.1V and then each cell should be individually recharged. The reason for this is that individual cells in a battery pack will have differing capacities and therefore when the battery pack is nominally discharged, each cell will have a different voltage. When they are subsequently recharged, maximum capacity will not be obtained. This problem has no solution when the cells in a battery pack are permanently connected and the connections are inaccessible; ie, when they are sealed inside the package. So for nicad battery packs, one of the discharger 20 SILICON CHIP circuits referred to above is the only practical solution. However, if you make up your own battery packs or use single nicad cells in any configuration, you can now obtain the best results with this single cell discharger. It will discharge any size single nicad cell down to 1.1 V whereupon it will turn itself off automatically. After that, the amount of current drawn from the discharged cell is minute (less than 20 microamps, in fact), so you don't have to worry if you leave the cell in the discharger and forget it. Features • Discharges either AAA, AA, C or D cells • Stops discharging at 1.1V cell voltage • Flashing LED to indicate discharging • Adjustable discharge current • 20µA cell current once discharged • Reverse polarity protection • Compact design l '-<" \1~~! .·• ·.,........... _ The discharger requires no external power supply as it gets its power from the cell it is discharging. This is the same concept as for the discharger circuits presented in the July and November 1992 issues of SILICON CHIP. Design approach A self-powered single cell discharger presents something of problem because the battery voltage is nominally 1.2V and this falls to 1.1V at the end of discharge. This is not enough to power conventional op amps or voltage reference sources, both of which are necessary if the circuit is going to do the job properly. Our solution to this problem is to use a DC-DC converter to step-up the cell voltage to around 9V. Fig.1 shows the complete circuit. IC1 is a TL496 DC converter. Power for IC1 comes from the nicad cell via Mosfet Ql. When START switch Sl is pressed, the cell voltage is applied to IC1 and it delivers close . to +8.8V across the 470µF electrolytic capacitor at its pin 8 output. This then becomes the supply rail for the remainder of the circuit which comprises a 5.1V zener diode, an LM358 dual op amp (IC2) and a few other minor components. IC2a is used as a comparator to compare the nicad cell voltage against a reference voltage. The nicad cell voltage is applied to the non-inverting input at pin 3 via a 2.7kQ resistor. This is compared to the inverting input at pin 2 which is set to 1. 1V. This voltage is derived from 5.1 V zener diode ZD1 via trimpot VRl. - START S1 2.7k STEP-UP VOLTAGE CONVERTER 01 MTP3055 +1.2V L1 50uH 470 + 16VWi 1'l 3 2 10k IC1 TL496 G NICAD+I CELL - 4 +8 .SV ..__ ._.- - ,~ 470 16VW + ! 7 REVERSE POLARITY PROTECTION 10k *R1 1.Sk 18k REFERENCE EXTRA DISCHARGE....__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___, 10 + l&VWi 7 *SEE TABLE L1: 33T, 0.5mm ECW ON NEOSID 17•732·22 TOROID NICAD CELL DISCHARGER K 7 B EOc VIEWED FROM BELOW Fig.1: the circuit uses DC converter ICl to step up the battery voltage to 8.8V when the START switch (S1) is pressed. This rail is then used to power comparator stage IC2a & LED flasher stage IC2b. When the battery discharges to 1.lV, pin 1 ofIC2a goes low, Qt switches off & removes power to ICl, & the LED stops flashing. Nate that the 5 .1 V zener diode has a zero temperature coefficient so that the 1.1 V reference will not vary with changes in temperature. With a charged cell connected to the circuit, pin 3 ofICZa will be higher than the reference voltage at pin 2. The op amp output at pin 1 will therefore be high. This voltage is applied to the gate of Q1 which feeds the nicad cell voltage through to IC1 when switch S1 is released. We have used a Mosfet here since it has only about 40mV across it when it is turned on. To compensate for this 40mV, a 470kQ resistor is connected between pins 1 and 3 of IC2a. This applies a small amount of hysteresis to the comparator. When the voltage across the nicad cell drops to just slightly below 1.1 V, the output of IC2a goes low, turning offMosfet Qt. Power is removed from the circuit and Q2 switches off. We haven't described the function of Q2 yet but we'll come to it in a moment. After Q1 and Q2 switch off, the only power drawn from the nicad cell is the leakage current of Q1 and Q2 which is negligible. We estimate the leakage to be about 40µA. LED1 DISCHARGING DISCHARGING FLASHER lows. The non-inverting input at pin 5 is tied to three 10kQ resistors - one to the +8.8V supply, one to 0V and the third to the output at pin 7. This voltage divider network means that the 10µF capacitor at pin 6 will constantly be charged and discharged between about +5.9V and +2 .9V. At the same time, the output at pin 7 will be a square wave with a frequency of about 3Hz and this drives LED 1 which then GDS functions as a discharge indicator. Notice the 2.2kQ resistor at the output of IC2b. This is connected to the +8.8V rail and current is drawn through it when ever the output at pin 7 is low. At other times, when pin 7 is high, current flows through LED 1. Thus, there is current flow via the output of IC2b whether the LED is on or off. This helps prevent voltage fluctuations from the nicad cell which could otherwise upset the operation ofIC2a. Nicad load current The total current drawn from the Discharge indicator Op amp IC2b is wired as a Schmitt trigger oscillator which is used to flash LED 1 on and off. It operates as fol- Most of the parts are mounted on a small PC board which clips into a plastic case. The battery holder is mounted on the lid of the case & is connected back to the board via flying leads. Note that the resistors are all mounted "end-on". MAY 1993 21 Fig.3: this is the full-size etching pattern for the PC board (code 14305931). nicad cell while it is discharging comprises the current drawn by the LED flasher, the zener diode reference, the comparator circuit and the step-up converter. This totals about 150mA. This is adequate for discharging AAA and AA size cells but more current is needed to discharge larger cells within a reasonable time. Transistor Q2 provides this extra discharge current. So if you want to discharge C or Dsize nicad cells, you will need to include resistors Rl and RZ, plus transistor QZ. Table 1 shows the values for Rl and RZ to suit the various cell capacities. If you wish to discharge cells of different capacities, you will need a rotary switch to switch Ql and RZ into or out of circuit. Alternatively, you could take the simple approach and build a separate discharger to suit each type of cell in use. Some readers may question how the addition of QZ and Rl will increase the current drain from the nicad cell by 70 milliamps. After all, a Mosfet Ql must be bent forwards as shown in simple calculation for the this photograph so that it clears the lid of the current through Rl will give case. the current as close to 5.5mA (I = [8.8V - 0.6V]/1.5kQ = 5.5mA). The point to remember here is that the 8.8V supply is being derived via the inverter based on ICl. The voltage step up ratio is about 7.3 and after the efficiency of the circuit is taken into account, the nicad cell has to deliver about 12mA for every lmA drawn from the 8.8V rail. Hence, when QZ and Rl are present, the circuit draws an extra 70mA. In order to draw an extra 180mA, as required for D cells, RZ is installed and a total of about 400mA is then drawn from the cell. To protect ICl against incorrect connection of the nicad cell, diode D1 and two lQ resistors are included in the circuit. These restrict the reverse voltage across ICl to less than 1V and thus protect it against damage. Construction We built our prototype Nicad Cell Discharger to suit AA size cells. It is housed in a plastic case measuring 83 x 54 x 30mm and has an AA size cell holder on top. A front panel label RESISTOR COLOUR CODES 0 0 0 0 0 No. Value 4-Band Code (1%) 5-Band Code (1%) 1 1 1 3 470kQ 18kQ 15kQ 10kQ 6.8kQ 2.2kQ 1.5kQ 680Q 10Q 6.8Q 1Q yellow purple yellow brown brown grey orange brown brown green orange brown brown black orange brown blue grey red brown red red red brown brown green red brown blue grey brown brown brown black black brown blue grey gold brown brown black gold brown yellow purple black orange brown brown grey black red brown brown green black red brown brown black black red brown blue grey black brown brown red red black brown brown brown green black brown brown blue grey black black brown brown black black gold brown blue grey black silver brown brown black black silver brown 0 0 0 0 0 0 0 22 1 2 SILICON CHIP TABLE 1 Cell Capacity 1B0mAh (AAA) Discharge Current 150mA Q no R1 R2 - - 500mAh (AA) 150mA no - - 1.2Ah (C) 220mA yes 1.5k - 2Ah (C,D) 220mA yes 1.5k - 4Ah (D) 400mA yes 1.5k 6.8 ohms measuring 48 x 26mm is fitted to the end of the case, along with the pushbutton START switch (S1) and the discharge LED. Apart from LED 1 and switch S1, all the circuit components are mounted on a PC board coded 14305931 and measuring 61 x 46mm - see Fig.2. This board is a press fit into the plastic case. After checking the PC board for any defects such as shorted or open circuit tracks, you can begin the assembly by inserting six PC stakes at the external wiring points, the two ICs and the diodes. Check the orientation of the ICs and diodes before soldering them in place. This done, insert trimpot VR1 and the capacitors. Note that the 470µF capacitors are quite squat - their length is only 12.5mm. We used capacitors from Altronics (Cat. R-5162) . If other types are used, they must not be longer than 13mm so that the PC board will fit into the case. All the resistors are mounted end on to conserve space. You should use your digital multimeter to make sure that you are inserting the correct value resistor in each position. Use Table 1 to check if you need to insert QZ and resistors Rl and RZ. Mosfet Ql is mounted with its leads bent so that it can lie horizontally over IC1 , while QZ must be inserted so that it does not sit higher than the electrolytic capacitors. Note that the photograph of our prototype board shows transistor QZ and resistors Rl and RZ in place, although they would only be needed if large cells were to be discharged. Inductor 11 is made by winding 33 turns of0.5mm enamelled copper wire on a Neosid toroid. Pass half the length through the centre of the core and wind on about 16 turns, then use the other end to wind on the rest of the turns. This done , strip the lead ends and solder them into the holes on the + DISCHARGING + START NICADCELL DISCHARGER Fig.3: this full-size artwork can be used as a template when drilling holes for the switch & LED indicator. PC board. The wound toroid is held in place using a transistor insulating bush and a 3mm machine screw through the centre. Secure it with a 3mm nut on the underside of the PC board. The front panel label can now be affixed to the end of the case and the holes drilled for the LED bezel and switch. After attaching the wires to the switch, sleeve the switch end with heatshrink tubing or insulating tape to prevent the bottom of the PC board from shorting to the switch contacts. Next, connect the switch wires to the PC board, then install the PC board in the case and push the LED into its bezel. The LED leads can now be soldered to the its stakes on the PC board. Make sure that the LED is connected with the correct polarity. Its anode lead is the longer of the two. The cell holder is attached to the lid of the case using contact adhes~ve or super glue. We do not recommend using screws and nuts since these could easily short between resistors on the PC board. Drill small holes so that you can pass the cell holder wires through the lid of the case and solder the wires to the PC board pins, as shown in Fig.2. Testing To test the unit, rotate VR1 fully anti-clockwise, insert a charged nicad cell into the holder and press S1. The discharging LED should immediately begin flashing. Check that the voltage between pins 4 and 8 of ICZ is about PARTS LIST 1 plastic utility box, 83 x 54 x 30mm 1 PC board, code 14305931 , 61 x46mm 1 front panel label, 48 x 26 1 single cell holder plus clip lead (see text) 1 momentary pushbutton switch (S1) 1 15mm LED bezel 1 Neosid 17-732-22 iron powdered toroid (L 1) 1 1-metre length of 0.5mm enamelled copper wire 1 transistor insulating bush plus screw & nut 1 10kn horizontal trim pot (VR 1) Semiconductors 1 TL496 DC converter (IC1) 1 LM358 dual op amp (IC2) 1 MTP3055A or MTP3055E N-channel Mosfet (01) 1 BC338 NPN transistor (02) 1 1N4002 1A diode (01) 1 BZX79C5V1 5.1V 500mW zener diode (ZD1) 1 5mm red LED (LED 1) Capacitors 2 470µF 16VW PC electrolytic (13mm length, see text) 1 10µF 16VW PC electrolytic 2 0.1 µF MKT polyester Resistors (0.25W, 1%) 1 470kQ 1 18kQ 1 15kn 3 10kQ 1 6.8kQ 1 2.2kQ 1 1.5kQ 1 6800 1 1 6.80 0.5W 2 10 10n Miscellaneous Heatshrink tubing for body of S1, tinned copper wire, hookup.wire, solder, machine screws & nuts. 8.8V and that the voltage across ZD1 is about 5.1 V. If all is well, rotate trimpot VRl clockwise until LED 1 stops flashing to verify that the comparator is operating. VR1 should then be adjusted so that the voltage between pins 2 & 4 of ICZ is 1.1 V (this sets the cell discharge voltage). The Nicad Cell Discharger is now ready to discharge your cells and help keep them in top condition. SC MAY 1993 23 we Have A Kit For Everyone • Even The Dog! .../t. It's Never Too Late To Save Your Speakers! You'll Have The Last Bark! Audio Power Meter Q Woofer Stopper Q Are you worr ied about burning out your loud speakers? This is a common problem , given the wide dynamic range of today 's compact discs. That's why we've developed a kit that monitors power levels. The Audio Power Meter connects across tne ~peaker output terminal of your amplifier (use 2 for stereo) and us_,s an LED bargraph display to indicate the output power level in 10 steps from 200 milliwatts to 100 watts so you don't have to worry about over-driving your speakers. It comes in short-form with PCB and components including IC sockets so that constr uctors can easily build it into existing equipment. At last a revolutionary kit that will keep the noise down in your neighbourhood' The Super Woofer is an electronic solution to noise pollution of the canine type' Because dogs respond to high frequency noises, the woofer stopper emits a sound which is sensitive to their hearing. It's enough to take the bark out of the meanest dog (without inflicting any harm on it). It comes complete with all components, hardware bits, PCB, case, front panel label, plug pack & piezo speakers . Cat K-3032 WOOFER STOPPER May '93 0 April '93 K,3032 $5995 OJCK SMITH EL ECTRON 1C S Cat K-3032 $2295 -------------0 Cat K-5372 Program The Tune Of Your Choice! Programmable Doorbell ;;; Cat K-3802 $3 9 95 Lets you program your own doorbell tune. With a maximum of 14 notes possible, it can even play two different tunes - one for the front door and one for the back and. if you get sick of a tune. you can change it 1 The kit comes complete with all components and hardware including battery holder. PCB and a deluxe doorbell case. Back doorbell switch is optiona l. (Batteries not included) ~ More Affordable Than Ever! 1GHz Frequency Counter vvQ Beware Of Units With Less Features! The Best In Town! Nicad Battery Discharger Q If you want the best performance from your NiCads. get this stylish battery discharger. With switchable vo ltage (8 ranges in total - 3.6, 4.8 . 6.0. 7.2. 8.4, 9.6. 10.8 & 12V), this easy-tobuild kit is ideal for most types of NiCads as used in cam-carders, cordless and cellular phones. radio controlled cars , cordless drills and Iap-top computers. The unit continuously monitors voltage and automatically cuts off the discharge current when the battery as a whole is fully discharged. There's also a switchable current discharge of 50mA and 200mA and a push-to-start button. This full-form kit has all components, hardware, case and a pre-punched (black anodised) screened front panel. - April '93 [z] $3495 F:i,i;?1 Cat K-3126 Nov '92 Two Channel Camcorder Mixer One of the things that decides whether a home video movie is a bore or a block-buster is the soundtrack. This inexpensive kit makes it easy to give your videos that Hollywood feel, comp lete with music and sound-effects 1 9V battery powered, the kit comes in full -form with PCB. case. front panel label, hardware. battery holder and all components, including IC socket. CAMCORDER ~ (Battery not included) op This 1GHz counter is an inexpensive variation on the 50MHz counter design published in February '93 Electronics Australia. By subst ituting an uprated display module and adding to the prescaler circuitry, a truly ingenious 1GHz counter can be built. The unit is designed with a seven digit display including a 'KHz / MHz' status indicator and a frequency rar.ge selector so that the user can select the relevant range ie : 2MHz. 20MHz. 50MHz & 1GHz. The Kit includes case . PCB, all components, ON hardware and a pre-punched and screened. perspex front panel. ',;=,i,=PO=W=£=R=C=HAN=N£=l=I=C..-=N=EL=>==MA=5=TE=R=I/!~ 0 QM~O MIN~•• '\,_~_ _ _ _ _ _ _ _ _ _ __,/ Cat K-7604 Frequency Range: Input A: 0-50 MHz Input B 50-1GHz Input Impedance: Input A: 1M OHM Input B : 50 OHM 24 SJLICON CHIP 1:A-t- April ,93 !,·, ~ $ 2995 Cat K-5408 March '93 PLEASE CHECK YOUR NEAREST STORE FOR AVAILABILITY, AS SOME KITS MAY STILL BE IN PRODUCTION. Clearance! Circular Bright 300 mcd Redled ~ CatZ-4075 ~ - - $1 Normally $1.65 In-line Fuseholder Perfect for ca r radios, transceivers or any low vo ltage app licati on. You can att ach your own cab li ng and there's no distance restriction! It takes standard 3AG iuses and comes complete with all hardware _ ,~ 85~ ~ CatP _791 ~ 10UP70~ ~C.: Heavy Duty 12 Volt Relay A low-,-ost heavy-duty 12-volt re lay that's ideal for cars. This quality Japanese-made relay has 25 amp single-pole switch ing con tacts and its casing inc ludes easy-mount bracketing spade lug terminals for super-fast termination . Cat P-8040 ~ $1295 o _ • a=~i ) Single AM Radio Receiver I.C. A 10-transistor tuned radio frequency circuit that provides a comp lete R.F amplifier, detector and AGC circuit. It requires on ly six externa l components to give a high quality A.M radi o. See B-2605 Dick Smith Funway volume 2 for circuit ap plication, single AM radio proj ect. Clearance! Electrolytic Capacitor 5600 mid 40V RG / CAN type computer grade lug mount electrolytic c a p a c i.t o. ~ r Cat R-4570 $495 It's f gre ime to Part · Dicka;e-~tained ciih Your cata10mg ith Electronf!·eared new ue - get ics 199j fre~~ from ,Yourse/f a filled e<!iflon! As hie Press, • With ·u • a wa"s . , informat·1 1 icy, deta·1'', its I ed hu 0n ab Pluge range of out our sour Produ electron. ever-useful cts section! ~eference a1lab1e. in May_ « , Cat Z-6520 : . lE»\ _- Was $5. 95 - Hurry in, last chance at this low price! Circuit Breakers Unlike the existing P-820 1 to P-8210 32V AC circuit breakers. th is range has a higher 50 / 250 vo lt AC rating. They are incredi bly good va lue - you won 't find them for • • • less at any other retai l sto_re' "' • 3 Amp Cat P-9900 $5.95 5 Amp Cat P-9902 $5.95 10 Amp Cat P-9904 $5.95 2-Pin 9-Volt Battery Plug As used in va lve radios. There are hundreds of other uses - maybe you can think of some! Cat P-3030 c 20 15 or more 15~ u., Buy in bulk from Dick Smith Electronics and you'll save over 10%! Grab a copy of the latest edition of Benchmark- it's packed with bargains and valuable advice and it's available at your local store! " DS XPRll!SS PHONE & MAILORD■R SERVICE Outside Sydney (FREE Call) 008 22 8810 Sydney And Enquiries - (02) 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. NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 7722 • Brookva le 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswoo d Chase 411 1955 • Chullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 47 7 6633 • Hurstvi lle 580 8622 • Kotara 56 2092 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastl e 611896 • North Ryde 878 3855 • North Sydney (Greenwood Plarn) 964 9467 • Orange 618 400 • Parramatta 689 2188 • Penr ith 32 3400 • Railway Squ are 211 3777 • Sydney City 267 9111 • Tam wo rth 66 17 11 • Wollongong 28 3800 ACT• Belconnen (06) 253 1785 • Fyshwick 280 4944 VIC • Ball arat 31 5433 • Bend igo 43 0388 • Box Hill 890 0699 • Coburg 383 44 55 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footsc ra y 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabet h St 326 6088 & 246 Bo urke St 639 0396 • Richmond 428 1614 • Ringwood 879 5338 • Springvale 547 0522 QLD • Booval 282 6200 • Brisbane City 229 9377 • Burand a 391 6233 • Cai rns 311 515 • Capa laba 245 2870 • Chermside 359 6255 • Maroochydore 791 800 • Roc khampt on 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Towns vi lle 72 5722 • Underwood 341 0844 •SA• Adelaide City 232 1200 • Beverley 347 1900 • Eli zabeth 255 6099 • Enfield 260 6088 • St. Ma rys 277 8977 WA• Cannington 451 8666 • Fre mantle 335 9733 • Perth City 481 3261 • Midland 250 1460 • Northbridge 328 6944 TAS • Ho bart 31 0800 • Launceston 344 555 NT• Darwin 81 1977 STORES ACROSS AUSTRALIA AND NEW ZEALAND B1479 MAY 1993 25 'I'HE B WOOFER STOPPER! Do you have a noise pollution problem of the canine type? If so, then don't take "woof' for an answer - zap it with the Woofer Stopper! By DARREN YATES Let's face it - there are fewer things in life more annoying than a dog barking at 4 o'clock in the morning. It doesn't matter what your problem is, it is seemingly insignificant when stacked against a flea-bitten mutt with the urge to howl in the wee-hours! It's also quite amazing how many owners disregard the noise their dogs make and the discomfort they cause other people. So much so, that barking dogs are a common source of friction between neighbours in urban areas. 26 SILICON CHIP However, there are several plans of attack for the frustrated neighbour. These involve exploding cans of dog food, armed combat with the offending mutt, and forcing it to watch endless re-runs of"Benji". Others are less savoury and we cannot mention them here but none are as elegant as our Woofer Stopper! We have had many requests for a dog zapper that really works - nothing to injure the animal mind; just something to act as a reprimand and make the dog shut up. The Woofer Stopper is the result of our endeavours. At the press of a button, it emits a retaliatory high-level supersonic tone that lasts for about nine minutes. Because this tone has a frequency of about 20kHz, it's beyond the range of human hearing but is well within the hearing range of a dog. The idea behind the device is that it packs a big enough aural punch to chastise the dog and knock the bark out of it. Basically, it's the high-tech equivalent of the good old fashioned but often ineffective "shaddup-yer-barking" bellow out the window. What's more, if the device is used on a regular basis, the animal eventually realises that it is going to be reprimanded if it barks and eventually ceases to be a problem. But the real beauty of the device is that your inconsiderate neighbour doesn't even know that you're getting your own back on his equally inconsiderate mutt. And of course, you can get back t5V tV1 16 16 11 10M 10 04A 2.2k 1k G D IC5a O 3 4013 - 2 C 0 s R 8, 9 7 7 12 3 7 06 MTP3055A G 10 IC2 4518 ENB 14 048 IC1 74HC4060 04 MTP3055A 14 7 7 7 33pFI 33pf+ tV1 t5V START S1 I 0.1+ 08 MTP3055A D G 14 16 i~i4 03 1 10 CK IC3 0 14 3 CK 4020 .015Hz R R 11 8 s 100 k IC5b 7 0 ,2 0 0 E I G0 C VIEW ED FROM BELOW 7 GDS 7 ';' D1 1N4004 D6 1N4148 0.1 6 ~ B 244.1Hz +sv---1 12VDC 300mA PLUGPACK I 100k S2 +5 V ·+ 1000 + 220n 16VWi 10 + D2 1N4004 16VW+ 7 7 + 7 'T' 81 I 12V I ...L.. WOOFER STOPPER Fig.i: the circuit uses IC1 & crystal Xl to generate a 4MHz timing signal which is divided down to 20kHz by IC2 & IC5a. IC5a provides complementary square wave outputs & these drive transistors Ql & Q2 which in turn drive an H-pack output stage consisting of Q4-Q7. IC3, IC4 & IC5b form the 9-minute timer. to sleep while the dog it still in the process of being zapped. Who was it that said "every dog has his day"? And now for the $64,000 question . Does it work? Well, from our own limited trials the answer is a resounding yes but we cannot guarantee that it will work with every dog. There are several reasons for this. First, some dogs are just plain stupid and that's all there is to it. Second, many older dogs are deaf and so wouldn't realise that they were being zapped by the Woofer Stopper, although older dogs are generally not problem barkers. And third, the range of the device is fairly limited which means that the dog has to be no more than about two doors away. A range of about 20 metres has been proven in practice but we haven't really had an opportunity to check the effectiveness of the device over longer distances. It certainly wouldn't stop a dog that's barking at the other end of the street. Circuit details Initially, we h ad ideas of a soundoperated mechanical arm that dropped half a hou se brick on the dog's head. However, most of the SILICON CHIP staff are dog lovers and insisted that this idea be scrapped in favour of an entirely electronic approach. Refer now to Fig.1 for the circuit details. We'll go through each circuit section step-by-step and explain how it all works. Timing for the circuit is provided by ICl, a 74HC4060 high-speed CMOS 14-bit counter and oscillator whose frequency is set by a 4MHz crystal. The reason for using the "HC" version of the 4060 is that a standard CMOS type cann ot be expected to run reliably at 4MHz with only a 5V supply. The two 33pF capacitors provide the correct loading for the crystal so -+ that it always starts reliably when power is applied to the circuit. The output from ICl is taken from pin 9, which is the direct 4MHz output from the oscillator. This is fed into IC2, a 4518 dual BCD counter configured as a divide-by-100 circuit. The resulting output at pin 14 (Q4B) is a pulse waveform with a frequency of 40kHz. From there, the signal is fed into D flipflop IC5a which divides by two . This not only divides the signal down to the 20kHz we want but also provides 50% duty cycle complementary square wave outputs at pins 1 and 2. Mosfets Q4-Q7 form an H-pack output stage in which diagonally opposite devices alternately conduct together, with the output device (a piezoelectric tweeter) forming th e bridge in the middle. Each Mosfet is an N-channel device which means that it turns on when its gate voltage is higher than its source voltage. The complementary signals from IC5a appear at pins 1 and 2 and drive transistors Ql and Q2 respectively via 22kQ resistors. These two transisMAY 1993 27 S2 SPEAKER SOCKET ing signals for the H-pack output stage, ICl also forms part of the delay timer circuitry. Its pin 3 output delivers a 244Hz square-wave signal (ie, the 4MHz clock signal divided by 214 ) and this is then fed to IC3. IC3 is a 4020 14-stage binary counter and is used to divide the 244Hz signal on its CLK input (pin 10) by a further 214 . The resulting signal is then divided by eight by 7-stage binary counter IC4 to produce a waveform which goes low for 536 seconds (ie, slightly less than nine minutes) . During this time, Q3 will be off and so QB turns on to enable the H-pack output stage (Q4-Q7). Reset circuit * SEE TEXT Fig.2: install the parts on the PC board & complete the wiring as shown here. Note the three vacant pads between ICl & Xl. To test the circuit, link the middle & bottom pads so that the tweeter delivers a ZkHz tone. When testing is complete, remove this link & link the middle & top pads instead. tors then provide the necessary drive current for the H-pack output stage. The H-pack output stage in turn is switched on and off by Q8 which forms part of the timer circuit. For example, let's assume that Ql is on (ie, pin 1 of IC5a is high) and that Q2 is off. Assuming that Q8 is also on, this means that Q4 and Q7 will be on and so current flows from the supply rail, through Q4, through the piezo tweeter, through Q7 and then through Q8 to ground. When the outputs of IC5a toggle, Q4 & Q7 turn off and Q6 & Q5 now switch on. Current now flows from the supply rail through Q6, through the tweeter in the opposite direction to before, and then through Q5 and QS to the ground rail. Because both ends of the tweeter are alternately switched between the positive supply rail and ground, we actually get twice the supply voltage developed across the tweeter. This ensures that the tweeter delivers adequate punch (the power is almost quadrupled), despite the limited supply voltage. As well as providing the initial tim- Flipflop IC5b performs several roles in the circuit. First, it ensures that IC3 and IC4 are correctly reset when power is first applied and at the end of each timing cycle. Second, it releases the reset lines on IC3 and IC4 and allows them to count when the START button (Sl) is pressed. And third, it turns Q3 on outside the timing period to disable the H-pack output circuit. When power is first applied, pin 10 (reset) of IC5b is momentarily pulled high via a 0. lµF capacitor and diode D3. This resets IC5b and so its Q-bar output (pin 12) goes high and also resets IC3 and IC4. At the same time, it turns on Q3 via D5 and thus Q8 is off and the siren driver circuit (ie, the H-pack output stage) is disabled. When the START button (Sl) is subsequently pressed, IC5b's set input is momentarily pulled high and so its Q-bar output switches low. This turns Q3 off and so Q8 now turns on to enable the siren diver circuit. IC3 and IC4 now begin counting up in response to clock signals from ICl. After about nine minutes, pin 6 of IC4 switches high and turns on Q3 via D6 to switch the siren off again. This high also resets IC5b via D4 which means that Q-bar of IC5b switches high again and resets IC3 & IC4, ready RESISTOR COLOUR CODE 0 0 0 0 0 0 28 No. 1 3 3 3 1 SILICON CHIP Value 4-Band Code (1%) 5-Band Code (1%) 10M.Q 100k.Q 22k.Q 1k!:! 220.Q brown black blue brown brown black yellow brown red red orange brown brown black red brown red red brown brown brown black black green brown brown black black orange brown red red black red brown brown black black brown brown red red black black brown ~ ., ... ,.,v:, . ., , . PARTS LIST ~ ~- '. ~ . ~ v",. ~ 1 PC board , code 03105931, 123 x 82mm 1 plastic zippy case, 198 x 113 x 62mm 1 momentary pushbutton switch (S1) 1 SPST toggle switch (S2) 1 black banana socket (optional) 1 red banana socket (optional) 1 2.5mm DC socket 1 3.5mm mono socket 1 12VDC 300mA plugpack 1 piezo tweeter (Jaycar Cat. CT1907, DSE Cat. C-2005) 1 4MHz crystal Semiconductors The PC board is secured to the lid of the case· using machine screws & nuts, with additional nuts used as spacers. Make sure that all polarised components are correctly oriented. for the next timing cycle. The high on Q-bar of IC5b also now holds on Q3 (via D5) and thus the siren is disabled until the START button is pressed again, whereupon the cycle repeats itself. Power for the circuit is derived from a 12VDC plugpack supply, with optional back-up provided by a 12V rechargeable battery (either nicad or SLA). As shown in Fig, 1, the incoming DC from the plugpack is fed via reverse polarity protection diode Dl and switch S2 to a 3-terminal 5V regulator. The output from the regulator is then used to power the ICs, while the siren driver circuit is powered from the 12V supply on the input side of the regulator. Construction The Woofer Stopper is built onto a PC board measuring 123 x 82mm and coded 03105931. Fig.2 shows the wiring details. Before installing any of the parts, check the PC board carefully for etching defects by comparing it with the published pattern. Usually, there will be no problems here but it's always best to make sure. Assuming everything is OK, begin the board assembly by installing the 12 wire links (don't forget the link between the gates of Q5 & Q6). The resistors and capacitors can then be installed on the board, followed by the diodes, ICs and transistors in that order. Make sure that all polarised parts are correctly oriented and be sure to use the correct part at each location. In particular, note that diodes Dl & DZ are 1N4004 types, while diodes D3-D6 are 1N4148s (or equivalent). The five Mosfets (Q4-Q8) are all installed with their metal tabs towards the back of the PC board, as viewed in Fig.2 (see Fig. l for the pin connection details). Push these devices down onto the board as far as they will comfortably go before soldering their leads. Finally, complete the board assembly by installing the 4MHz crystal (it can go in either way around). Testing The completed board assembly must now be tested to confirm that it is operating correctly. How do you test the circuit when you cannot hear its output? The answer is to modify the circuit slightly so that it produces a ZkHz tone instead of a 20kHz tone. The first step is temporarily con- 1 7 4HC40.60 14-bit counter & oscillator (IC1) 1 4518 dual BCD counter (IC2) 1 4020 14-bit binary counter (IC3) 1 4024 7-bit binary counter (IC4) 1 4013 dual D flipflop (IC5) . 1 78L05 5V 100mA regulator 3 BC548 NPN transistors (01-03) 5 MTP3055A or MTP3055E power Mosfets (04-08) 2 1N4004 silicon diodes (D1 ,02) 4 1 N4148, 1 N914 diodes (D3-D6) Capacitors 1 1000µF 16VW electrolytic 1 10µF 16VW electrolytic 2 0.1µF 63VW MKT polyester 2 33pF ceramic Resistors (0.25W, 1%) 1 10MQ 3 100kQ 3 22kQ 1 2.2kQ 3 1kQ 1 220Q Miscellaneous Hook-up wire, solder, screws, nuts & washers nect the START switch, DC input socket and the tweeter to their respective pads. This done, take a close look at the PC board and locate the three vacant pads between ICl and the 4MHz crystal. These pads are used as a crude switch, with the centre pad as the wiper. When the middle and top pads are bridged, the circuit produces a Z0kHz tone. When the middle and bottom pads are bridged, the circuit MAY 1993 29 ~ =ff#------,----- Fig.3: this full size artwork can be used as a drilling template for the two front panel switches. WOOFEB STO:PPEB produces a 2kHz tone (ie, the clock signal is now taken from pin 7 ofICl). To test the unit, link the middle and bottom pads, connect the plugpack supply and switch on. Now press the START button. You should immediately be greeted by a 2kHz tone from the tweeter. In fact, it's a good idea to cover the tweeter with a blanket before switching on to lessen the impact on your eardrums. The next step is to check the timing circuitry by confirming that the tweeter stops sounding after approximately !:'I~ I o-o !.!..o M (J\ in 0 M ~ 0 o-cfibo Fig.4: this is the full-size etching pattern for the PC board. 30 SILICON CHIP + START POWER nine minutes. If you cannot stand to have the tweeter blaring away for this period of time, switch off, disconnect it and connect your multimeter (set to the 20V range) to the collector of Q3. This done, switch on and press the START switch again. Q3's collector should immediately go high (ie, to +12V). It's then simply a matter of confirming that Q3's collector goes low again some nine minutes later to end the siren period. Once you've confirmed that everything is operating correctly, remove 0 C\. + the link to the bottom pad and link the middle and top pads instead. The circuit will now produce the desired 20kHz square-wave. The three unused pads near diodes Dl & D2 interface to an optional remote control receiver (to be described next month). Final assembly All that remains now is to install the board inside the specified plastic case. The PC board mounts on the lid of the case (which now becomes the base) and can be used as a template for marking out its own mounting holes. Secure the board to the lid using machine screws and nuts, with additional nuts used as spacers.. You will also have to drill holes in both ends the case to accept the power input sockets and the output socket, plus holes in the front panel for the two switches. A 2.5mm DC socket is used for the plugpack supply, banana sockets are used for the battery and a 3.5mm mono socket is used for the output to the tweeter. If you don't wish to use the optionaL back-up battery, just leave its terminals out of circuit and omit D2 and its parallel 220Q resistor. Finally, try to position the tweeter as close to the offending dog as possible, while keeping it (the tweeter that is) out of the weather. Probably the best location is under the eaves of your house. SC INFRA RED NIGHT VIEWER ._.. One 3mW laboratory Siemens tube; used one used quality 2mW tube, one universal 12V laser inverter ki$ for a total of: 99 LARGE LENSES C Two pairs of these new precision ground AR coated lenses were originally used to make up one large symetrical lens, for use in IBM equipment. Made in Japan by Tominon . The larger lens has a diameter of 80mm and weighs 0.5kg . Experimenters delight at only: ' ·• · , • ".. , 1 These matching components were removed from brand new IA tank viewers. They include a large low light objective lens, a large prefocussed IA image converter tube, a power supply or power supply kit to suit the tube and an adjustable eyepiece assembly. Make a professional infra red night viewer. ON SPECIAL AT: s150 UNINTERRUPTABLE POWER SUPPL V (UPS) Contains a 24V DC to 240V AC, 50Hz Sine Wave Inverter! Use it as a portable mains power supply on boats, in caravans, for solar powered systems, or simply for its original function : As an uninterruptable power supply for a computer. We have ·a limited stock of 300 watt UPSs. They are complete except for a few mounting screws. Some of these may be faulty or in need of a few modifications. A copy of the service manual (18 pages) which includes the circuits, layouts, test procedures, and modifications will be provided with each unit. All the necessary UPS electronics are contained on one PCB which is easy to service. Employs modern high frequency switching techniques in the inverter section. A smal separate PCB contains a mains filter. The four mains output sockets on the rear panel are all individually switched by illuminated switches. The UPSs used two 12V 6.5Hr batteries connected in series; not provided. Inexpensive and common locally available devices are used throughout. LM324s, 40106s, TL494, 7815, LM317, IRF540s, IRF830s, etc. $60 The giveaway price for the complete unit? We may also have available some later model UPSs for around $100. Some 600 watt new units may also be available. For the set. IR LASERS $15 for the pair LASER POINTER If you always wanted a laser tube but couldn't afford one, how about a used 1mW tube. High quality pen sized 5mW laser diode pointer for teachers, doctors, etc. ON SPECIAL FOR $169 s29 VISIBLE LASER DIODE BARGAIN LOOK THE CHEAPEST SmW VISIBLE LASER DIODE EVER OFFERED Small PCB assem based on a ULN2232 IC. Thi s device has a built in light detector, filters, timer, narrow angle lens, and even a siren driver circuit that can drive an external speaker. Will detect humans crossi ng a narrow corridor at distances up to 3 metres. Much higher ranges are possible if the detector is illuminated by a remote visib le or IA light source. Can be used at very low light levels, and even in total darkness with I A LED. Full information provided. The IC only is worth $16! Our price for the assembl y is: $6 ea. or 5 for $25 FM TRANSMITTER KIT - Mkll Use it to charge and or maintain batteries on boats, for lighting, solar powered electric fences, etc. Make yo ur own 12V-4W solar panel. We provide four 6V-1W solar panels with termin ating clips, and a PCB and components kit for a 12V battery charging regulator and a three LED charging indicator. See March 93 S.C. Incredible value! $42 6.5Ahr. Panasonic gel battery $35. Electric fence PCB and all onboard components kit $40: See S.C. April 93. REDUCED PRICES! This precision collimator assembly is supplied with a brand new laser diode to suit. Produces a well collimated laser beam at 780n M/5mW. Barely visible. We also supply a PCB and components kit plus instructions, for a suitable digital driver circuit that can be used to complete the laser transmitter. Suitable for communications, data links, perimeter protection, barcode reading, medical use, etc. s59 f1_·""i'·_1. . · . ' . " ·~ . ,,t- . We can also supply a similar kit which includes a laser diode, unmounted lens, and a driver kit $39 PROJECTION LENS A 5mW gunsight at a super reduced price. s229 Includes one "Free" rifle or pistol mount. I SECOND GENERATION TUB We have a limited supply of some 18mm fibre optically coupled 2nd generation image . intensifier tubes. These are ex•military and may have some minor blemishes, but all produce full gain . With low light lenses these will produce useful images with as little as starlight illumination. Can also be IA assisted with IA LED's or low power torches, in rare situations where this may be required . The tubes require a 3V battery and a switch to make them operational. The viewer illustrated uses one of these tubes. It was constructed using some low cost plastic tubing and matching fittings for the case, a camera lens, and a low cost eyepiece. Plastic jewellers eyepieces can be used. FOR THE TUBE AND THE SPECIFICATION SHEET SSSO Probably the cheapest visible red helium neon laser and power supply ever offered, ANYW HERE! The kit includes a PCB, transforme r, and all the components needed to make a 12V operated laser power supply, and a used laser tube with a power rating in the 0.5-2mW range. The PCB and all the onboard assembly is the same as the one used in our EHT Generator (it also now comes with a PCB), but a few extra necessary components and corresponding instructions are provided with the kit. Incredible value at: sso For the 12V inverter kit and a visib le red laser tube. The EHT generator kit is available separately for $23. 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 system? Experimenter$ de~ht at ONLY 3U This HIGH QUALITY LOW COST FM transmitter should not be compared to other simple designs. The frequency shift due to extreme antenna handling, and or changing the supply voltage by ± 1V at 9V will produce less than 30KHz deviation at 100MHz! Less than 0.03% shift: STAYS PUT! It has very high audio sensitivity. It will pick up sound sources 10's of metres away from the microphone. Transmitter Speclllcations: Supply voltage 6-12V, Consumption <at> 9V = 3.5mA, 50uS preemphasis, 40Hz to greater than 15KHz response, greather than 60dB SIN ratio, audio sensitivity: 20mV, frequency stability (see notes): 0.03%. PCB dimensions: 26mm X 42mm. A solder masked and silk screened PCB and a prewound shielded coil make for easy construction . The kit includes the PCB plus all the on-board components, an omnidirectional electret microphone, and a 9V battery clip, at a TOTAL COST of: s11 Or you can purchase three kits for a tota l of $30. UNUSUAL ITEMS & COMPONENTS 20KV PIV-5mA Av./1A Pk. Fast diodes ... $1.50 ea. 3KV PIV- 300mN30A Pk. Fast diodes . . 60c ea. 30V PIV- 1N25A Pk . Schottky Barrier diodes . ..... .. 45c ea. 680pF/3KV Disc ceramic capacitors ........... 30c ea. 1000pF/15KV Disc ceramic capacitors $5 ea. 0.01 uF15KV Disc ceramic capacitors .... .. .. $1.80 ea. Flexible DECIMAL KEYPADS with PCB connectors to suit ............... $1 .50 ea. High quality UNIDIRECTIONAL ELECTRET microphone inserts . .......... $8.50 Stage quality UN IDIRECTIONAL DYNAMIC microphone inserts .................... $9.60 780nM IA diochroic filter (20nM bandpass) for IA detectors . .. ... ... .... $20 FRONT SURFACED MIRRORS: 10mm X 10mm X 1mm $5 20mm X 20mm X 1mm $6 200mm X 150mm ....... $8 X-Y LASER SCANNER KIT Commercial X- Y scanners for laser deflection cost thousands of dollars. This scanner compromises by using two DC motors to achieve good results. Th e motors don't spin, but simply vibrate around the set position. The PCB and component kit include rectification and filtering (power supply) , audio preamplifiers, audio filtering, and two separate power amplifiers to drive the two deflection motors. The scanner is powered by a 16V AC-900mA plugpack. Produces a totally randqm two dimensional display which is depended on the sound picked up by the microphone. The power amplifiers can also be driven from external oscillators and/or pretaped signals recorded on a stereo cassette recorder. A short form kit includes a screened and solder masked PCB, all the onboard components, an electret microphone, two motors, and two lightweight mirrors, s44 240V-16V/900mA AC-DC Plugsafe: $16 extra. MORE UNUSUAL ITEMS AND COMPONENTS 100 LED BARGRAPH DISPLAY: Yes 100 LEDs, plus IC control ci rcuitry, all surface mounted on a long strip of PCB. Simple, a 4 bit binary code selects which one out of the 10 LED groups will be on, whi lst another 4 bit binary code selects which one of each group of 10 LEDs will be ON . Latching inputs are also provided. We include a c'ircuit and a connecting up diagram . Special introductory price .. $7 ea. MINIATURE FM TRANSMITTER: Ready made and enclosed in a small black metal case which also contains the small battery (G13) and a microphone: 32 X 32 X 11 mm. We don't recommend this use, but some would advertise this unit as a miniature " bug " at many times more than our price of .......... $39.50 FM MICROPHONE: Features a stainless steel case and an unidirectional microphone insert , powered by two AA batteries. High quality at .......... .... $39.50 OATLEY ELECTRONICS PO Box 89, Oatley, NSW 2223 Telephone: (02) 579 4985 Fax: (02) 570 7910 MAJOR CARDS ACCEPTED WITH PHONE AND FAX ORDERS P & P FOR MOS 1 MIXED ORDERS : AUSTRALIA : $6 ; N.Z. (Air Mail) : S10 MAY 1993 31 A remote vol11me control for hifi systems Have you ever wanted to adjust the volume of your stereo system from the comfort of your armchair? Now you can with this high quality Remote Volume Control. It can control the balance setting too & has excellent distortion & noise specifications. By JOHN CLARKE How many times have you been listening to your favourite piece of music and wanted to adjust the volume? Many CD players now have remote volume control but other program sources don't. This Remote Volume Control overcomes that problem and can be added to just about any system. Apart from having infrared remote control, this project overcomes the limitations of the standard dual ganged potentiometers which are used for volume adjustment on almost every amplifier. All normal potentiometers become noisy with use and since the volume control is the one we use most, 32 SILICON CHIP it is the most likely control on your amplifier to become noisy. A second problem with volume control potentiometers is their poor "tracking" between the left and right channels, particularly at low volume settings. This means that as you turn the volume down, the sound tends to shift to one side of the room and then needs adjustment with the balance control. With the SILICON CHIP Remote Volume Control, there is no noise because there are no moving parts and the tracking between channels is superb - better than any dual-ganged potentiometer can ever be. There is also negligible distortion and excellent separation between channels and you can set the volume level far more precisely than with any normal volume control. The SILICON CHIP Remote Volume Control unit is housed in a one-unit high (ie, 44mm-high) rack-mounting case. It can be connected between your preamplifier and power amplifier if you have separate units. Alternatively, it can be connected into the Tape Monitor loop of an amplifier or stereo receiver. A separate Tape Monitor loop is built into the unit so that you don't lose this facility. As a matter of fact, if you normally use a CD player and tape deck as your only program sources, you could use this Remote Volume Control in front of a power amplifier in what would appeal to purists as "minimalist hifi". The system would have no input selector (apart from the Tape Monitm: switch), no tone controls and no knobs. In fact, one of our staff members has used just such a system in conjunction with the Studio 200 power amplifier described in the February 1988 issue of SILICON CHIP. The audio performance of the Remote Volume Control is genuinely hifi. As can be seen from the specifications, the noise and distortion are extremely low and separation between channels is excellent. What the figures mean is that the sound quality will not be degraded in the least. Block diagram Fig.1 shows the main features of the unit. The infrared remote control transmitter unit has five buttons: Up and Down volume, Left and Right balance, and Mute. The Up, Down and Mute buttons are duplicated on the Remote Volume Control unit itself. The volume setting is displayed on a digital readout which shows the attenuation in decibels from 0dB (maximum volume level) down to -88.5dB. The volume setting can be changed via the Up and Down buttons in 1.5dB steps. If you hold down the Up button, the volume setting will increase at a rate of about 6dB per second. Similarly, the Down button causes the volume setting to reduce by 6dB per second. This rate is about the same as that provided by the motor-driven remote controls on some commercial amplifiers. Balance display The balance display is a 9-LED bargraph which simulates the setting of a horizontal slider control. When the balance is centred, the centre LED lights. When the balance is shifted to the right, the LEDs to the right will be successively lit and vice versa. Balance adjustment is made in 1.5dB steps from 0dB to 9dB and then fully off. Three LEDs either side of centre indicate 3dB balance steps (ie, -3dB , -6dB and-9dB), while two LEDs lit at the same time indicate the inbetween steps (ie, -1.5dB, -4.5dB and -7.5dB). When the extreme left LED is on, the right channel is fully off. Similarly, when the extreme right LED is on, the left channel is off. The Mute facility enables you to reduce the gain by 21dB - similar to the mute control on normal amplifiers. The mute condition is indicated by seven of the nine balance LEDs lighting up. When the balance display is indicating the mute mode, balance adjustment is not possible. All nine LEDs of the balance display light in mute mode when the volume setting is -67.5dB or more. This simply indicates that both channels are muted beyond the normal -88.5dB range. The heart of the remote volume control circuit is a 68HC705C8P microprocessor. This is used to drive the digital readout and LED balance display, and to monitor the signal from the infrared remote control. However, its main function is to drive a dual logarithmic digital to analog (D-A) converter. It is this device which controls the level of the audio signal. ment is noise injection due to the high speed switching of its internal circuitry. This can be minimised by careful layout and shielding but the only really effective way to stop it is to shut down the microprocessor. To do this we use a method known as "static idle". This means that the microprocessor is only active when it is updating volume or balance settings and is static at other times. This facility is normally used in order to save power consumption in battery operated microprocessor applications. We're not concerned about power consumption here; just about noise. Static idle The companion remote control transmitter has five pushbuttons to control volume (Up & Down), balance (Left & Right) & muting. One problem that can occur when using a microprocessor in audio equip- LEFT v-----, DUAL LOG · D·A CONVERTER AUDIO INPUT RIGHT u - - - - - , BALANCE D D LEFT D DOWN AUDIO OUTPUT RIGHT D MUTE D MICROPROCESSOR UP INFRA RED TRANSMITTER c, ,_, c, ,_,c, ,_,. 00963036900 ATTENUATION DISPLAY (dB) BALANCE DISPLAY BALANCE A Fig.1: block diagram of the Remote Volume Control. The microprocessor decodes the incoming code picked up by the infrared receiver & controls an AID converter to vary the audio signal level. It also indirectly drives the LED displays to show the volume level & channel balance. MAY 1993 33 r--------------- -- --- -------1 I R R Vin VDD R -'WV\----, Vin A RFB A I I 2R 2R I I I I I RFB I I OUT I I I I I A GND ~----------------------~ ____ J Fig.2: the arrangement for a standard 17-bit R-2R DIA converter. In this application, the DIA converter is used as a programmable resistance to control the gain of an op amp & thus the audio level at the output. DAC A DAC B RFB B A dual logarithmic DI A converter is used to control the volume of the audio signal. However, analog to digital conversion and back again does not happen. All signals remain analog. How can this be? The answer is that we are not using the DI A converter to perform any signal conversion. Instead, we are using it as a programmable resistance. nal is supplied with a fixed reference voltage of typically +5V. When all switches (S1-S17) connect to the OUT position, the Wii Vin B D GND A GND 5V at Vin passes directly Fig.3: block diagram of the AD7112 DIA to the op amp output. If all converter IC. It has eight data inputs & these the switches are connected are buffered & decoded to control two 17-bit to ground, then the signal DIA converters (DACs), thus making it ideal is attenuated by a factor of for use in a stereo system. 217 , orto about 38µV. Other Basic concept settings of the switches provide voltages which are between bit code which provides logarithmic Fig.2 shows the concept. This diaattenuation. When the 8-bit code is gram depicts the arrangement for a these two values. standardR-ZRDIAconverter. ThevoltOur circuit does not use 5V DC but 0000 0000, the attenuation is 0dB. Each increase in count (0000 0001, age at Yin is applied to the inverting applies the audio signal to Vin. Hence, input of an op amp via a series string the signal at the output of the op amp 0000 0010, etc) increases the attenuaof resistors of value R which are can be directly controlled by the DI A tion by 0.375dB. shunted with resistors of value ZR. converter. Our circuit provides volume steps The ZR value resistors can be conThe DAC we have selected is the of 1.5dB, so we do not need 256 sepanected independently either to the AD7112 from Analog Devices. Its in- rate levels. Instead, only 60 steps are inverting input of the op amp or to ternal block diagram is shown in Fig.3. required. This is done by tying the DB0 and DB1 lines low (ie, to 0V) and ground via switches S1-S17. It has eight data inputs (DB0-DB7) Note that we are using a 17-bit DI A which are buffered and then decoded varying only the DB2-DB7 lines. converter (ie, with 17 switches) but with an 8-bit to 17-bit decoder. The 8Actually, the AD7112 provides two only four bits are shown. bit input provides 256 volume set- 17-bit DIA converters, one for each In normal DI A use, the Vin termi- tings and these are decoded to a 17- channel and both are controlled by the DB0 to DB7 inputs. This allows us to provide the balance facility so that the left and right channel gains can be Measured Performance individually adjusted. Signal-To-Noise Ratio ....... 110dB unweighted (20Hz-20kHz bandwidth) Circuit description Total Harmonic Distortion .................................. <0.005% (20Hz-20kHz) Now check out Fig.4, the main circuit diagram. This uses 11 ICs, several LED displays, three 3-terminal regulators, and various resistors, capacit-0rs and diodes. IC1 is the microprocessor, IC2 -IC6 are the LED display components, IC7-IC9 are the DI A converter and op amps, and IC10 and IC11 are for remote control reception and decoding. IC1 is the microprocessor which controls the rest of the circuit. Its clock circuit is based on a 3.579545MHz crystal connected to pins 38 & 39, Frequency Response ........................ ... .......... . DC to 50kHz (-3dB point) Separation Between Channels ... ........ -89dB at 20kHz; -90dB at 10kHz; -106dB at 1kHz; -11 0dB at 100Hz (measured with undriven channel. input loaded with 1kQ) Attenuation accuracy (1kHz, 25°C) ....... <1dB to -54dB; <2dB to -66dB; <2.5dB to -88.5dB Channel tracking accuracy .. .. ............... ....... ........ ................... <±0.25dB Maximum input signal ................................................................ 8V RMS Note: all performance measurements made with respect to 1V RMS input at 0dB attenuation 34 SILICON CHIP Most of the parts are mounted on two PC boards which are soldered together at right angles. The display board (top) carries three 7-segment LED displays for volume level indication, a LED bargraph to indicate channel balance, an acknowledge LED, & three pushbutton control switches (Mute, Down & Up). 10 goes low, pulling the IRQ input of although the microprocessor actually operates at half this frequency; ie, at IC1 low via diode D11. This awakens IC1 and the decoded outputs of IC11 1.78MHz. at pins 11-15 are now read by the The PA0-PA6 output lines of IC1 control ICZ, IC3 & IC4, the 4511 BCD microprocessor which acts accordto 7-segment display drivers. These ingly. Pin 10 ofIC11 also drives LED 1 (ACK) , which indicates when an indrive 7-segment LED displays via frared signal is received. 3300 limiting resistors . The display IC11 decodes the signal from IC10, drivers are accessed by IC1 only when the volume level is to be changed. a Plessey SL486 infrared receiver. This Outputs PA7 and PB0-PB7 of IC1 . IC has an infrared photodiode (IRD1) at its input to pick up signals from the control the balance display LEDs via remote control handpiece. The sigDarlington transistor drivers IC5 & IC6. nals are amplified and filtered before The Down, Up and Mute switches on the front panel are monitored by they appear at the output (pin 9). the PD0, PD1 and IRQ (interrupt reThe capacitors connected to pins 2, quest) lines of IC1. Normally, these inputs are tied high via 10kQ resistors to the +5V supply. When the Down Main Features switch is pressed, the PD0 input is pulled low and the IRQ input is also • lnfrared remote control of pulled low via diode D6. Similarly, volume , balance and mute the Up switch pulls PD1 low and pulls • 88.5dB volume control range the IRQ line low via D7. in 1.5dB steps The Mute switch pulls both PDQ • 3-digit display of volume and PD1 low via diodes D9 and D10 setting in dB and also pulls the IRQ line low via • 21dB mute DB. A low IRQ level tells the microprocessor to "wake up" from its static • Balance control in 1.5dB idle mode and check the PD inputs. steps to -9dB, then fully off Infrared signal decoding The PD2-PD5 and PD7 lines of IC1 monitor the data outputs of infrared decoder IC11. When valid data is received by IC11, its Data output at pin • Microprocessor uses "static idle" mode to minimise noise • Tape monitor loop • Initial volume setting -48dB 3, 5, 6 & 15 of IC1 roll off the frequency response to effectively filter out 100Hz signals. This is necessary to make the circuit immune to interference from 50Hz mains-powered lighting. IC11 operates at 614kHz, a frequency set by ceramic resonator XZ. This and the data rate set by links to pins 3 & 4 must match the settings inside the remote control handpiece (ie , the transmitter). Digital to analog converter IC7, the AD7211 dual D/A converter, is driven by the PC0-PC7 output lines of IC1. The PC0-PC5 lines provide the data to IC7, while the PC6 and PC7 lines drive the WR and A/B inputs of IC7 to provide balance control. As noted above, although IC7 has eight data inputs, we are using only inputs DB2-DB7. The DB0 and DB 1 inputs are simply tied to 0V. The left and right channel inputs are fed via the tape monitor switch Fig.4 (next page): the full circuit details for the Remote Volume Control. ICl is the microprocessor & this controls DIA converter IC7. This in turn controls the gain of op amps IC8 & IC9 to vary the volume. ICl also controls the LED displays via IC2-IC6. Instructions for the microprocessor are picked up infrared diode IRDl & processed by IClO & ICll. MAY 1993 35 ► +5V LEFT TAPE PLAYB ACK G LINE IN 17 LEFT RL1A +15V 220pF RFBA ;.n,m OUT A S2a 4 VIN A OAC A OUTPUT A GNO 1 LINE TO TAPE 13 14 I 7 TAPE MONITOR RIGHT I D81 RIGH RL1B OBO 15 CS 5 DGNO I TAPE PLA Y8ACK k 7 mEb S~b ~"''"' OUTPUT OUT B 20 18 VIN B OAC 8 082 083 0B4 DBS 0B6 087 WR A/8 12 11 10 8 9 ' 220pF LINE LINE IN 7 IC7 AD7112CN +15V 19 RF88 1200 0.5W 16 7 1200 0.5W - i 47 o+ 25VW 7 V NEG I 012 1N4004 RL1 7 7 470 +5V + + 6.8 47 10+ 0.22 22+ f:,; LK1 16 IRD1 BPW50 IC10 SL486 1- 4 15 0 8 IC11 MV601 C 8 A X2 614kHz 15 14 13 12 100pF I 100pF .015! K 14 13 12 11 011 4.7k _ DATA OE CLR I 10 1N914 7 0.15! 10k LE01 ACK A 7 10k 10k 16 MOM 7 D8 7 0.1+ V NEG. REG1 IN F1 500mA A 270 SW + 10 25VW+ 5x0.1 f +5V 7 REG2 +21V 240VAC IN +15V 1:1! ·::·11 + + 2x0.1 N- - - - - - - - - - E ~ CASE 36 S1ucoN . CHIP FLOAT 05 1N4004 EARTH -21V REG3 REMOTE VOLUME CONTROL - - oo LEFT - - 1 - - - -- - RIGHT-9 9 00 +5Y BALANCE DISP4 10k ,r :~ : ~ : ~ : ' :c; : c; : ). i, :~ ~ : 9x33011 10 11 12 13 14 10 11 12 13 1+ 8 + 40 7 '31 I3 PB0 PB1 PB2 22 23 24 25 26 27 28 6 8 + IC8 ULN2003 3 4 5 7 6 4 5 1 R PA7 21 IC5 ULN2003 PC7 PB3 PC6 PB4 PCS PBS PC4 PB6 PC3 PB7 4 12 13 14 15 ffi m .~. jK IGO 16 GIO 17 18 19 PC2 PC1 PCO IC1 MC68HC705C8P 38 4.7M l l X1 '"'"'I 'ij 39pf 39 ■ ■ 31 32 33 34 38 2 29 30 PD2 l'A0 PD3 PD4 PA1 PDS PA2 PA3 PD7 PA4 IRQ PAS PA6 PD0 PD1 11 10 9 8 7 6 5 I +SY -fo 5 LE --16 6 D 4 3 b a 2 d 13 12 11 A B I tlg 8 10 9 7 6 4 2 1 9 10 I,-:-,b e/ 'C OISP1 HDSP5303 -!-3,8 - - 3 D b a - - - - - -- 2 6 C C 13 12 11 d +5Y 7 1 A B I 8 + -- 8 4 2 9 10 I Dq g C d 8 10 9 15 14 +5Y • DISP2 HDSP5303 DP 33011 5 - - - - - ATTENUATION (dB) - : 7 I -!-3,8 A 7x33011 1 ,_, I IC4 4511 13 12 11 I : 7 b a 7 1 B C 4 15 14 10 9 LE 3 g 2 5 16 ,__ 8 IC3 4511 7x33011 a d 5 LE 4 15 14 : : 7x33011: --18 6 IC2 4511 C +SY 7 1 C ,_, ,_, 6 4 2 1 9 10 DISP3 HDSP5303 -!-3,8 - - -- --------- MAY 1993 37 PARTS LIST Receiver 1 1-unit high rack mounting case 1 dark red Perspex sheet, 150 x 20 x 2.5mm 1 screen printed front panel, 480 x 44mm 1 self-adhesive rear panel label, 180 x 34mm 1 PC board, code 01305931, 283 x 161mm 1 PC board, code 01305932, 283 x39mm 1 2 x 15VAC 20VA low profile transformer (Universal Electronics) 1 2AG panel mount fuse holder 1 500mA 2AG fuse 1 mains cord & plug 1 cord grip grommet 1 2-way mains terminal block 1 SPST mains switch (S1) 1 DPDT PC mount push on/off switch and knob (S2) 1 DPDT 12V relay (RL 1, Altronics S-4150) 2 4-way RCA socket panels 3 snap action PC-mount switches (S3-S5) 1 SPOT toggle switch (S6) 2 40-pin machine IC sockets 4 rubber feet 1 heatsink, 25 x 30 x 12mm 1 2.5-metre length of shielded cable 1 300mm-length of twin shielded cable 1 750mm-length 0.8mm tinned copper wire 5 cable ties 31 PC stakes 4 5mm standoffs 2 solder lugs 1 Murata CSB624P 614kHz ceramic resonator (X2) (S2a & S2b) to pins 4 & 18 of IC7 and its outputs at pins 2 & 20 connect to IC8 & IC9, respectively. The RFB connections from pins 3 & 19 of IC7 set the gain of each op amp to -1, while the 220pF capacitors provide high frequency roll off to prevent instability. Note that RFBa and RFBb inside IC7 each has a value of between 9.3kQ and 15kQ and these essentially match the series impedance of the lasertrimmed R-2R ladder in the DACs. 38 SILICON CHIP 1 3.579545MHz parallel resonant crystal (X1) Semiconductors 1 MC68HC705C8P programmed microprocessor (IC1 - available from SILICON CHIP) 3 4511 ?-segment display drivers (IC2-IC4) 2 ULN2003 7-way Darlington drivers (IC5-IC6) 1 AD7112CN dual log D/A converter (IC7) 2 OP27G op amps (IC8,IC9) 1 SL486 IR receiver (IC10) 1 MV601 IR decoder (IC11) 1 7805 5V 3-terminal regulator (REG1) 1 7815 15V 3-terminal regulator (REG2) 1 7915 -15V 3-terminal regulator (REG3) 6 1N4004 1A rectifier diodes (D1-D5,D12) 6 1N914, 1N4148 diodes (D6-D1) 1 10-segment LED bargraph (DISP4, Altronics Cat. Z-0180) 3 HOSP 5303 0.3-inch common cathode LED displays (DISP1 DISP3) 1 3mm red LED (LED1) 1 BPW50 IR diode (IRD1) Capacitors 1 4700µF 25VW PC electrolytic 1 4 70µF 25VW PC electrolytic 1 330µF 25VW PC electrolytic 1 47µF 16VW PC electrolytic 1 22µF 16VW PC electrolytic 6 10µF 25VW PC electrolytic 1 10µF 16VW PC electrolytic 1 6.8µF 16VW PC electrolytic 1 1µF 16VW PC electrolytic 1 0.22µF MKT polyester Thus, the input resistance seen by each op amp is more or less constant, regardless of the signal level. This is important otherwise the noise performance of the op amp would b£ prejudiced. In fact, the selection of the op amp in this ap plication is quite critical. We needed a low noise amplifier with good slew rate capabilities plus high gain. Also required are low input bias currents and low input offset voltage. 1 0.15µF MKT polyester 9 0.1 µF MKT polyester 1 0.015µF MKT polyester 1 .0047µF MKT polyester 1 .0047µF 250VAC polyester 2 220pF ceramic 2 100pF ceramic 2 39pF ceramic Resistors (0.25W, 1%) 1 4.7MQ 2 120Q 0.5W 610kQ 1 47Q 1 4.7k 1 27Q 5W 32 330Q Miscellaneous Heatshrink tubing, screws, nuts, solder, etc. Remote transmitter 1 remote control case (DSE Cat. ZA-4666) 10 chrome buttons for case (DSE Cat. ZA-3929) 1 PC board, code 01305933, 62 x 59mm 1 Dynamark front panel label, 73 x63mm 1 9V battery & battery clip 5 click action momentary switches (S1 -S5) 1 MV500 remote control transmitter (IC1) 1 MTP3055E N-channel Mosfet (01) 2 CQY89A IR LEDs (LED1 ,LED2) 1 Murata CSB614P 614kHz ceramic resonator 1 220µF 16VW PC electrolytic capacitor 2 100pF ceramic capacitors 1 10kQ 0.25W 1% resistor 1 10Q 0.25W 1% resistor 1 2.2Q 0.25W 1% resistor To meet these requirements, we have specified an OPZ 7GP for both IC8 and IC9. A,. relay is used to isolate the left and right channel outputs of the op amps at power on and power off. This prevents any turn-on thumps from being fed through to the external power amplifiers. Power supply Power for the Remote Volume Control is derived from a mains trans- former with two 15VAC windings connected in series to give 30VAC. This is rectified by diodes Dl -D4 plus D5 and filtered by a 4700µF capacitor in the positive supply line and a 330µF capacitor in the negative supply line. The resulting ±21 VDC rails are applied to 3-terminal regulators REGl, REG2 and REG3 to obtain +5V, +15V and -15V rails. The ±15V rails power the op amps, while the +5V rail powers the rest of the circuit. The relay coil is supplied from the negative rectified line at the junction of diodes D3, D4 & D5 via two 120Q 0.5W resistors connected in series. These resistors reduce the supply to a nominal -12V. xxxoo 10k - Below: the Remote Volume Control can be installed in the tape monitor loop of an integrated stereo amplifier or between the preamplifier & power amplifier where separate units are used. It includes its own tape monitor loop so that you don't have to sacrifice this facility. + T 13 UP 51 9V 1 I ..J.. mxx + A DOWN 52 100XX IC1 MV500 MUTE 53 011XX A BAL S4 - 110XX L BAL S5 101XX 16 .,. 18 17 X1 614kHz Transmitter circuit Fig.5 shows the circuit for the infrared remote control transmitter. It comprises a single IC, a ceramic resonator, two infrared LEDs, a Mosfet, several switches and a few resistors and capacitors. ICl is a Plessey MVS00 chip which provides PPM (pulse position modulation) signals suitable for driving a transistor and infrared LEDs. In stand- A 220 + 16VWi 100pF + + G05 100pF IR REMOTE CONTROL TRANSMITTER Fig.5: the transmitter circuit is based on an MV500 IC. Each time one of the switches is pressed, a unique code appears at the pin 1 output & this drives Ql & two infrared LEDs. by mode, the IC draws only 2µA which means that the circuit does not need an on/off switch. The MV500 operates with an oscillator frequency of 614kHz as set by its ceramic resonator, so that it matches the conditions of ICl 1 in the Remote Volume Control. Five pushbutton switches are connected between five of the row input pins (2 -6) and the +9V supply via a single lOkQ resistor. When a switch is pressed, a unique code for that switch is delivered from the output at pin 1 and this drives the gate of Mosfet Ql via a lOQ stopper resistor. Ql then drives two infrared LEDs (LED 1 & LED 2) via a series 2.2Q current limiting resistor. These two LEDs are driven very hard and are fed with 1.3A current pulses of 15µs duration (20% duty cycle). The 220µF capacitor across the 9Vbattery supplies the peak current to the LEDs. Next month we shall present the assembly details and complete the construction of the Remote Volume Control. SC MAY 1993 39 SERVICEMAN'S LOG Front little acorns, giant oak trees growThis month's story is something like the acorn that grew. It grew into several stories within the main story, each important in it's own right. How best to present these without losing the main thread presented something of a problem, so bear with me if I digress along the way. It all started with a routine phone call from a customer, complaining that his TV set was "on the blink". In more detail, the set involved was a National Panasonic TC-2690, a 63cm model using an M14 chassis. By "on the blink" he meant that it was completely dead, so I simply said "OK, bring it in". I left the delivery job to him for a good reason. This set is housed in a large, double-ended, lowboy cabinet and, since he has a utility, it was no problem for him to transport it. The M14 chassis is one of a whole series of"M" chassis; M9, MlD, Mll, etc, up to at least M16. I have dealt with several of these in the past but FRACARRO SAVES.•• ... more than $1 o. from every UHF television antenna you buy. Fracarro's 4PUN for better performance from weak UHF signals. Peter C. Lacey Services Pty. Ltd. P.O. Box 678 (74Fulton Rd.) Mount Eliza 3930 Tel:03 787 2077 Fax:(03) 787 3460 ACN006893438 40 SILICON CHIP this was my first time for an M14. This chassis was produced between 1986 and 1988 and, apparently, was fitted to only a few models. Anyway, the set was duly delivered. When I switched it on, I realised that the description "completely dead" was not strictly true. It sounded more as if it was dying, or being tortured to death, judging by the way the power supply was screaming. Clearly, there was a serious overload of some kind, somewhere. It didn't take long.to confirm my initial suspicion; the horizontal output transistor, a 2SD1632, was shot. No problem; I had one in stock. This transistor comes in a plastic flat pack (TOP-66) encapsulation and is mounted on a heatsink on the side of the chassis. I fitted the replacement, taking care to use plenty of heatsink compound; an important precaution with such devices in heavy duty roles like this. Another precaution was to make a routine check of two potential problem areas , based on past experience of the "M" chassis in general. One is the soldered joints to the horizontal output transformer pins, while the other concerns the horizontal driver transformer pins. Faulty joints in these areas are a frequent cause of failure of the horizontal output transistor. But there were no problems here, so the set was plugged in and fired up. And everything worked fine. The only sour note - and it was nothing to do with the original failure -was that the picture tube seemed to be in rather poor condition; certainly much poorer than I would have expected for a set only about five years old. But beyond making a note to draw the owner's attention to this - for my own protection as much as anything - there was little I could do at this stage. I refitted the set in its cabinet and ran it in the workshop for a couple of days. I then attempted to contact the owner but his work takes him out of town from time to time. I eventually contacted his wife, who said she would pass the message on. In the end, it was something like 10 days before he eventually turned up, during which time I had let the set run all day and every day in the workshop. So that should have been that. But it wasn't, of course. Two days later he was on the phone complaining that the set - which he described in most colourful terms - was " ... on the blink again". There was no point in trying to determine whether it was displaying the same symptoms; it was "on the blink" and that was that. So I said "bring it in and I'll have another look at it". In fact, it was quite some time before he brought it back; close to a month, in fact. Yes, I know that sounds strange but one encounters some strange types in this game. I know he has another set and apparently pressure of other things had intervened. Anyway the set eventually turned up in the back of the ute and we manhandled it into the shop. And I realised that the lapse of time had not improved his opinion of the set, though I suspect that many of his thoughts were really meant for me, even though he stopped short of directing them at me. In short, he was not a very happy customer. Well, I wasn't very happy myself. A bouncing set is never a cause for celebration, if only because it usually .3'.:>" 0"3CIIV ~ VT o~oil-\.OIJGH l 'SUS'P~T "tr{A, MANY OF H\S TH0UGH"'f'S W~Re: 'REAt-L'-f tll\E"N'T" FOR ~e:. means more time spent on the job; time for which one can seldom charge. And when the customer is clearly in no mood to accept any explanation, the situation is doubly worrying. Anyway, at the first opportunity, I pulled the back off, plugged the set in and switched on. There were more tortured screams from the power supply and another shot horizontal output transistor. If I was not happy before, I was even less happy now. There was obviously no point in simply replacing the transistor. There was a "nasty" lurking somewhere in set, just waiting to pounce. Unless I could find it - and be sure I had found it - I dare not return the set to the customer. At a servicing level, I obviously had to restore the set to working order before I could start searching for the fault. So a new transistor was fitted and the set came good, just as it had done before. I let it run but not before I had set up the CRO to monitor the collector and base waveforms of the transistor, both of which appeared to be quite normal at this stage (CRO points 17 and 16 respectively in the manual). A diversion Having set things up as above, I had the urge to monitor everything for a while, in the hope that some clue might emerge. I knew it was long shot, because the set had previously behaved faultlessly for 10 days in the workshop. But I wanted some reason to hang around for an hour or so . Looking at the picture on the screen, I was reminded of the poor picture tube performance. But was it the picture tube or could it be a circuit fault? And if it was a circuit fault, might it possibly have some bearing on the main problem. This was long shot but stranger things have happened. A far more likely fault was low heater voltage, so that was the first thing to check. The heater is fed from a winding on the horizontal output transformer, via a 2.7Q 2W resistor. And being AC at 15,625Hz, it cannot be measured with a conventional meter. I use one of the Fluke 87 series meters, which will measure this quite accurately. And yes, there was something not quite right, But it wasn't a low voltage; instead, it was on the high side at 6.7V. Why was this so? And to what extent was this responsible for the premature aging of the tube? More on this latter point in a moment. I backtracked to the 2. 7Q resistor (R523) and checked it. It was spot on and that left me in something of a quandary. I had no idea why the voltage was high, only that it was wrong. But what could I do? Increasing the resistor to reduce the voltage would only make the performance worse. On the other hand, I could reduce the resistance and restore the tube performance but that would · further shorten its life. Finally, I decided to take the easy way out and leave the setup as it was. So just how significant was that over-voltage in the life of the tube? It doesn't sound much - a mere 6%, in fact - but all the indications are that it is quite serious. For a start, it must be remembered that the power dissipated by the heater increases at a greater rate than the voltage increase. If the heater resistance was constant, it would increase as the square of the heater voltage. The heater resistance is not constant, however, as it increases with temperature, but the tendency towards the square law remains. At a more practical level, there is plenty of workshop evidence to sup- VIDEO & T.V. SERVICE PERSONNEL TV & VIDEO FAULT LIBRARIES AVAILABLE AS PRINTED MANUALS $85 +P/H BOTH MANUALS T.V. & VIDEO $145 +P/H OR AS A PROGRAM FOR IBM COMPATIBLES OR AS AN APPLICATION PROGRAM FORD-BASE 111 PLUS FOR MORE INFO. CONTACT TECHNICAL APPLICATIONS PO BOX 137 KENMORE 4069 OR FAX/PHONE (07) 3781064 Now, I'm going to digress here, because this is what actually happened. MAY 1993 41 I 2SD1632? There wasn 't much in the driver circuit - just the driver transistor (Q500), the driver transformer (T500), two resistors (R515 and R526), and two capacitors (C525 and C527). SERVICEMAN'S LOG - CTD The penny drops r---1 - r--··- · 7 r-C-Vw~ - - · ---r-VV\, l. - - I ...J Q501 Q551 ZSM51 8Vp -p 20,,sec . Fig.1: this is the horizontal output stage of the M11B chassis in the National TC2656. The waveforms are similar to those of the M14 chassis as observed on the CRO but the indicated time scale could be misleading. port the claim that it is serious. I have another set on the bench at the moment with a sick tube, which is also running with 6.7V on the heater. The set is still within its 3-year warranty, with about six months to go. It will probably be replaced but two and a half years is a ridiculously short life for any tube. All of which has started me on a witch hunt. I have found at least half a dozen sets with varying degrees of over-voltage, ranging from 6.4V to the 6. 7V already quoted. That raises the question as to what kind of tolerance is acceptable. The best figure I can recall - and this is from the monochrome days was issued by a local tube manufacturer and was to the effect that increasing the heater voltage from 6.3V to 6.5V could reduce the tube life to repeat "to" - something like three or four years. If I remember correctly, this warn- ing was prompted by a particular model TV set which was gobbling up picture tubes like a kid let loose in a chocolate factory. Again this was due to a modest over-voltage but it was just too much for the heaters. So what has this to do with the original fault? Well, it enabled me to rule out any connection between it and the poor tube performance and that was important. It also enabled me to hang around the set long enough for something to show, which it did. I suddenly realised that the picture was shrinking horizontally and that the transistor base waveform, as shown on the CRO, was changing. The alarm bells started to ring. I'd seen that shrinking effect before somewhere and knew it meant that the transistor was about to be destroyed. I pulled the power plug and saved the transistor. More importantly, I now had a clue. What would cause a change in the waveform at the base of the Fig.2: the horizontal output stage of the M14CM chassis (National TC-2698) is similar to the M11B circuit but uses different transistors. The resistors and capacitors were easily checked and were spot on. That left only the transistor and the transformer. And this was when the penny - which must have been teetering on the edge - suddenly dropped. In my October 1990 notes, I described a similar horizontal shrinking problem in a National TC-2656 fitted with an Ml lB chassis. This chassis uses a similar driver circuit to the M14 and an identical driver transformer (designated TLH6476). After much travail, the fault was eventually traced to this transformer. Well, that was good enough for me. In a toss-up between the transformer and the transistor, history favoured the transformer. And, since I had one in stock and they are worth only a few dollars, I lost no time in fitting it. I set things up again, with the CRO as before, and let the set run. And I let it run all day and every day for the next week. Then, with no sign of trouble, I fitted it back in the cabinet and let it run for several more days. When it still didn't misbehave, I was cautiously optimistic that I had found the fault. I hadn 't forgotten the last episode, when it ran for more than 10 days before it failed but I had to call a halt somewhere. It was time to contact the owner. In fact there was a further delay; he didn't respond for some three weeks, during which time I flogged the set every minute that I could. By the time he did collect it, I was convinced that the fault really had been found. The only charge I made was for the parts replaced , with no charge for labour. And I emphasised that he should contact me immediately if there was further trouble. All that was several months ago and, at a recent check, all is well. So I consider the point proven. What's more, I sense that I am once again in his good books. He was quite lavish in his praise for the trouble I had taken, so all ended well. Another case But there is a good deal more than that to this story. I have had another 42 SILICON CHIP model TC-2698 with the same fault since then, this time with an M12 chassis. With the benefit of experience, this was an easy one but the nature of the transformer failure remains a mystery. I have taken the matter up with National's service department but they are equally mystified; my three cases are the only ones that have been reported. Even so, I find it hard to believe that my cases are the only ones that have occurred. I suspect that there may have been others but that the true cause has not been diagnosed. Just how many of these sets have bounced and how the situation has been handled, we shall probably never know. More to the point, perhaps, is the exact nature of the failure and how it damages the output transistor. What happens internally may well remain a mystery but I have been trying to make some waveform observations in an effort to explain why the transistor is destroyed. Unfortunately, these observations have been only fleeting. As I have learned from bitter experience, when the circuit goes into its horizontal Fig.3: these waveforms are from the M14 output stage, as displayed on a Hewlett-Packard dual-channel CRO. The upper waveform is from the base of Q501 (10V/div & 20µs/div), while the lower waveform is from the collector (500V/div). The arrows on the extreme right indicate zero reference. shrink mode, it's only seconds away from destroying the horizontal output transistor. And at around $20 a pop, I am not keen to sacrifice any more than I can help. So I have not been able to do more than glance at the CRO and register that the waveform has changed. There AUSTRALIAN MADE TV TEST EQUIPMENT 10% discount on all test equipment. 15% discount on two or more items. SHORTED TURNS TESTER Built-in meter to check EHT transformers including split diode type, yokes and drive transformers. $78.00 + $4.00 p&p is no time to make any measurements or records. A normal waveform is shown on the accompanying Ml 1 circuit, which is essentially the same for the M14 circuit, and an actual CRO pattern printout from an M14 chassis is also shown. This was made with a Hewlett- ANTRIM TOROIDAL TRANSFORMERS HIGH-VOLTAGE PROBE Built-in meter reads positive or negative voltages from 0-50kV. For checking EHT and other HT voltages. $98.00 + $5.00 p&p 1· DEGAUSSING WAND Strong magnetic field. Double insulated for your safety with momentary switch operation. 240V AC 2.2 amps. As important as a soldering iron ! $75.00 + $10.00 p&p REMOTE CONTROL TESTER 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 ¼ .. '"".' :~ ~~--tf) ;' ,. From $19 exchange plus post & pack Cheque, Money Order, Visa, Bankcard or Mastercard Tli v~.•• TUN~~s J Phone (02) 774 1154 ···< 216 Canterbury Rd, Reve~bJ~.~:i~. 2212, Fax (02) 774 1154 • Now made in Australia. • Standard range 15VA co 2kVA. • Large ex-stock quantities available. • Competitive pricing available for OEMs & resellers. • Simply the best transformers all round. HARBUCH ELECTRONICS PTY LID 90 George Street, Hornsby NSW 2077. Telephone (02) 476 5854. Fax (02) 476 3231. MAY 1993 43 SERVICEMAN'S LOG - CTD Packard 2-channel digital CRO, model HP54600A, which has a facility (called ScopeLink) to feed the pattern into a computer and store it on disc. It can then be displayed on the computer screen or printed out. This is an extremely valuable facility which makes it possible to build up a store of waveforms that are not shown in a manual. In fact, the dual scan CRO pattern is more meaningful than the separate waveforms on the circuit, because it presents both waveforms on the same timebase, making it much easier to relate the instantaneous behaviour of one with the other. This pattern shows that the output transistor has a small positive voltage applied to it for most of the 64µs line period but is turned off for about 12µs at the beginning of the scan. This triggers the accompanying 900V collector pulse. The shape and amplitude of this pulse would be governed largely by the resonant characteristics of the horizontal output transformer. This background information may help us answer the inevitable questions at some time in the future. In the . meantime, we can only speculate as to why the transistor fails and a number of theories have been suggested by various colleagues. Most have subsequently been discarded but there is one that seems reasonably creditable. This puts the blame on the spikes on the base waveform, which accompany the 12µs turnoff period, particularly the longer one of the two. This has an amplitude of around 32V in the CRO waveform shown. This value should be within the base/emitter ratings of the output transistor but if the faulty transformer is generating much larger spikes, they may well exceed this rating. Significantly, the faulty transistors were broken down completely; base to emitter, base to collector and collector to emitter (the latter breakdown via the base). And that's about all the comment I can offer at the moment. I realise that it is not a complete answer. And not every output transistor failure in this circuit will be due to this cause; most will be normal internal failures. But, if you encounter two failures in rapid succession, be warned. End of story? Not quite. My discussion with the National service department raised another matter of concern regarding the 2SD1632 transistor. When I first de- ,~ v." 0'AtRS \ ""- . . \~ \ \ . ~------ ~ \; ;;,_ 11,ur.,~ ,~pv-,•c,~-- '---- - :Y\JST HOW W\AN.'( OF 1'-\E:.SE. SE,S 14A\JE: 8001'\CEC> ANt> \-\OW 1'\-\e:. SlTUAT\ONa \-\A~ ~E.E.N H~N'O\..E.D ~HA\-.\- ?ROBASL-'< NE.VER \<).\OW we:. 44 SILICON CHIP . scribed these transistor failures, the first question the technician asked was whether I had replaced the faulty unit with the original type. I assured him that I had used a type 2SD1632 but that didn't satisfy him. "Are you sure it's an original replacement?" I couldn't get the drift of his question immediately and asked him to clarify it. But I added that I would have bought it from either his own spare parts department or from another spare parts dealer whom we both know to be thoroughly reliable. Bodgie transistor It was only then that he realised that I wasn't as up to date as he thought I was. And he explained that there was a bodgie version of this transistor going around, apparently from an Asian manufacturer. The original 2SD1632 is made by Motorola and is stamped with its type number and the registered Motorola logo; ie, a stylised letter "M" in a rectangular frame . The bodgie device also carries the type number and th_e Motorola logo and appears identical to the genuine device. On that basis there is no way to pick the bodgie from the real thing. Fortunately, there is a way to pick it. There is a slight difference in the plastic moulding. With the package lying flat on the bench, check the space between the terminals. The bodgie device has a number of vertical ridges in this area, whereas the genuine device is quite smooth. A quick check of my own stocks revealed that I have only the genuine version. In fact, I have not seen a bodgie one but I am assured they do exist. In fact they have turned up in small pockets in Queensland and Victoria, as well as NSW. It is unlikely that a bodgie unit will be found in a set, unless the set has already been serviced in that section. But check existing stocks, or stocks being purchased. It is possible that some suppliers may be stocking them quite innocently. · And that really is the end of my trials and tribulations for this month. Unfortunately, I am not exactly the bearer of goodj:idmgs (I'm the kind who would have come to a sticky end in the good old "shoot the messenger" days) but at least readers should now be better informed about these chassis and the pitfalls to watch for. SC REMOTE CONTROL BY BOB YOUNG Unmanned aircraft - the ultimate in remote control During the 1991 Gulf War, the usefulness of unmanned aircraft passed almost unnoticed. What did not pass unnoticed was the suffering of the pilots captured after being shot down over Iraq. However, if unmanned aircraft were used to their full capability, there would be very little risk of pilot casualties. · In the Vietnam War, America lost more than 2500 manned aircraft and about 5000 of her.airmen were killed. Nearly 90% of all US servicemen taken prisoner were pilots and crewmen. Interestingly enough, the Vietnam War saw the birth of a successful remotely piloted vehicle (RPV) in the form of the Ryan 147 series. This jet RPV is now out of production but lives on in the form of the Chinese CHANG HONG 1, a reverse engineered AQM-34N which was shot down over China around 1970. It was unofficially reported that up to 20 MIG fighters made between 30 to 50 passes at this little drone before they shot it down. The story is always the same in regard to the survivability of these tough little aircraft. They are very hard to shoot down. Consider the following quotes: (1). "This ... target was ... flown against the concentrated gunfire of the (British) Home Fleet during an exercise in the Mediterranean. For two hours, every gun in the fleet tried in vain to destroy this lone, slow and fragile target, but it was recovered safely". (2) . "Thousands of rounds ofradardirected fire from a sophisticated air defence gun, as well as hundreds of rounds of fifty calibre, were expended on an unmanned vehicle flying well within range. The unmanned vehicle flew on without a scratch". There is little room for doubt about the survivability ofRPVs but the truly noteworthy feature of these quotes is that they were issued at an interval of 47 years. The first quote, which comes from Richard A. Botzum's "30 Years of Target Drone Aircraft", was discussing a flight made by a Fairy Queen biplane in 1933. The second was quoted during a US Gorernment hearing in 1980. The Vietnam experience If more proof is needed of the survivability ofUMAs (unmanned aircraft), then consider the following statistics. In the same war that saw 5000 US airmen killed in the skies over Vietnam, drones flew a total of 3435 operational sorties in the years between 1964 and 1975. Of these, the recovery rate in the early days, was approximately 84 % . In the latter years, as more sophisticated models were introduced, the recovery rate climbed to well over 90%. After Vietnam, the proponents of UMAs were confident that RPVs had proved their case and were set to become a major new "force multiplier" in military thinking. Instead, the expected upturn in fortunes failed to materialise and five years after Vietnam, the USA did not have one single operational RPV in its inventory. It was left to Israel to prove the point on the value ofRPVs and to take the case to its logical conclusion. Israel first recognised the value ofRPVs during the Yorn Kippur war of 1973, when it was able to reduce its manned aircraft losses by using inexpensive Chukar decoys to deceive and saturate Egyptian SAM batteries along the Suez Canal. Shortly after that war, the Israeli government charged the IAI and Tadiran companies with developing small, versatile, low-signature RPVs, able to send back real-time intelligence via a direct video link, and capable of being operated in the field by ordinary soldiers after only 3-6 months training. The Scout and Mastiff mini-RPVs came into their own in June 1982 when Israel launched it's "Peace for Galilee" offensive against Syrian forces in Lebanon. Some of the drones, equipped with radar reflectors to simulate full size aircraft, acted as decoys to draw the fire of Syrian gun and missile batteries in the Beka Valley. Whilst this deception was in progress, other RPV s carrying explosive charges remained undetected by Syrian radars, enabling them to home in on the radars' emissions and destroy them on impact. The air defence batteries, thus blinded were totally vulnerable to atMAY 1993 53 tack by manned strike aircraft, which wiped them out completely. In this object lesson in the combined use of manned and unmanned aircraft, not one single Israeli pilot was lost and Syria quickly paid Israel the compliment of acquiring Russian drone systems for its own forces. How it all began How did all of this automated mayhem begin? Interestingly enough, as with most things electrical, with none other than Nikola Tesla. He had begun active work on building remotely controlled devices in 1893, although capable of a multitude of operations, but the consummation of my labours was delayed until 1897 ... When first shown in the beginning of 1898, it created a sensation such as no other invention of mine has ever produced."' "His basic patent was obtained in November, only after the examiner in chief had come to New York and witnessed the performance of his vessel, for he claimed it was unbelievable." "These first robots, he wrote in 1919, he had originally considered crude steps in the evolution of the art of Teleautomatics. As he had con- "The famous woman pilot Hanna Riech then undertook to fly the monster and identified the problem as a Gyro toppling under launch "G" forces. The rest is history." the concept had occurred to him earlier. During the next two or three years, he had built several mechanisms that could be actuated from a distance and showed them to laboratory visitors, but the destruction of his laboratory by fire interrupted these activities. The following quotes are from the book, "Tesla, Man Out Of Time" by Margaret Cheney: "In 1896 he wrote ' ... I designed a complete machine ceived it: 'The next logical improvement was its application to automatic mechanisms beyond the limit of vision and at a great distance from the centre of control, and I have ever since advocated their employment as instruments of warfare in preference to guns ... In an imperfect manner it is practicable, with the existing wireless plants, to launch an aeroplane, have it follow a certain approximate course, and perform some operation at a distance of many hundreds of miles"'. The above passages refer to Tesla's radio controlled boat and submarine models which were demonstrated publicly in the late 1890s. They featured two separate RF channels which were used in an AND gate configuration. The basic patents used in these very early models played havoc with some heavyweight inventors and the courts were kept busy for many years. Marconi was affected as we will see, and the computer industry was subsequently denied patents on AND gate devices. Tesla filed his basic radio transmission patents on September 2nd, 1897 and they were granted as Patent Nos. 645,576 and 649,621 on March Zoth, 1900. Later they would be contested in long litigation by Marconi but first Tesla would sue the Italian Government for infringement. Marconi used Tesla's basic patent 645,576 to develop the equipment he used on December Zoth, 1901 to transmit the letter "S" across the Atlantic from Cornwall to Newfoundland. H. Otis Pond was walking with Tesla that day and commented to Tesla that it looked as though Marconi had got the jump on him, to which Tesla replied: "Marconi is a good fellow, let him continue. He is using 1 7 ofmy patents". On June 21st, 1943, the US Supreme court reversed an initial finding in Marconi's favour to rule that Tesla AF 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: 54 SILICON CHIP Here's what you get: • A 1.6 metre prime focus dish antenna. complete with all the mounting hardware. • One super low-noise LNB (1.4dB or better). • One Ku-band teedhorn and a magnetic signal polariser. • 30 metres of low-loss coaxial cable with a single pair control line. • lntrared remote control pre programmed satellite receiver with selectable IF & audio bandwidth. polarity & digital readout. Your receiver is pre-programmed to the popular OPTUS transponders via the internal memory. AV-COMM Pty Ltd, PO Box 225, Balgowlah NSW 2093. Ph: (02) 949 7417. Fax: (02) 949 7095. All items are available separately. Ask about our C-baild LNBs. NTSC-to-PAL converters. video time date generators. FM2 & EPAL & Pay TV hardware. GEs GARRY, please send me more information on K-band ~ I satellite systems. I Name: _ _ _ _ _ _ _ _ _ _ _ __ I Address: _ _ _ _ _ _ _ _ _ _ _ __ 1 1 - - - -- - - - P'code: _ _ _ _ _ 1 Phone: _ _ _ _ _ _ _ _ _ _ _ __ I ACN 002 174 478 10/92 Taken in August 1977, this photograph shows three versions of Australia's very successful pilotless target aircraft, the Jindivik. In the foreground is one of only two manned versions, while in the background is the first pilotless version. The current version of the Jindivik is just in front of the hangar. had anticipated all other contenders with his fundamental radio patents. The next step in the development of the RPV occurred in 1913 when Lawrence Sperry first tested his gyro stabiliser - the world's first automatic pilot - in a Curtiss biplane. A mere four years later, an improved version became the heart of Sperry's "aerial torpedo ", which made several successful flights for the US Navy from Sperry's Long Island airfield. British experiments In 1917, the British War Office, concerned with the heavy losses of British aircraft to the "Fokker scourge" across the Channel and the effects of the Zeppelin bombing raids over England, looked into the possibility of developing pilotless, remotely controlled aircraft for interception and ground attack missions . A young Army officer, Second Lieutenant A. M. Low, was placed in charged of the newly-formed RFC Experimental Works and given the task of applying his expertise in radio technology to the problem. Under the cover name of AT (Aerial Targets), a series of small aircraft, some designed by such pioneers as H. P. Folland and Thomas Sopwith, were produced for trials. During Law's first public demonstration at Upavon in March 1917, the AT misbehaved so badly as to provoke Major Gordon Bell, one of the War Office observers, into the now classic remark that he "could throw my bloody umbrella farther than that". Subsequent efforts were scarcely more successful and thus no ATs became operational. The main problems lay in the launch techniques and aircraft stability and in fairness to Low it must be pointed out that when the launch was successful, the radio techniques he developed could exercise long range control from a "mother" aircraft. The Nazis had exactly the same problem with the Vl (Doodle-Bug) in WWII and after many failures of the unmanned version, a manned version was built. This fix was to no avail and there followed several fatalities. The famous woman pilot Hanna Riech then undertook to fly the monster and identified the problem as a Gyro toppling under launch "G" forces. The rest is history. The concept of manned prototypes of the earlier UMAs was quite common and there was even an early manned version of Australia's very successful UMA, the Jindivik. These days, obsolete manned fighter aircraft are routinely converted to drones at the end of their safe service life. Next month we will continue this discussion of remotely piloted vehicles of which there are several dozen different types in service with defence forces ar~mnd the world. References. (1). Air International, February 1992, Unmanned Aircraft directory. (2). Jane's Battlefield Surveillance Systems 1992-93. (3). Tesla, Man Out Of Time, by Margaret Chaney. Prentice-Hall, Inc. Englewood Cliffs, N.J. 07632 1981. MAY 1993 55 VINTAGE RADIO By JOHN HILL A few old receivers from the 1920s A while back, I was fortunate enough to get onto a few old receivers from the 1920s. Actually, I tell a lie - in this instance, they came to me. All I had to do was answer my telephone. These sets were owned by a collector who was selling up. And he is not alone in this regard; quite a number of collectors have been forced to sell up during the past 12 months or so. Many people are enduring hard times at the moment and, when finances become strained , unessentials such as hobbies are the first to go - particularly when those pay cheques stop coming in. On the other hand , many such collectors have had to face the harsh reality that, due to the recession, their collections are not bringing the prices they originally paid. The true value of something is only what someone is prepared to pay for it at that particu- lar time. If it doesn't sell, then the asking price is greater than its current worth. The person who was offering me his radios was strictly a collector. He simply acquired old radios and stored them in outside sheds. He made no attempt to clean up any of his sets or make any effort to restore them to working order. From this description, readers can well imagine the generally neglected condition of these receivers. They were dirty, dusty and looked decidedly unloved. Add the aroma of mouse infestation and the picture is complete. There were four radios with four horn speakers, plus three horn driv- This is the home-made 3-valve TRF receiver. Its cabinet has been built from roughly dressed poor quality timber not unlike that used in packing cases. 56 S1LJCON CHIP ers and an upright Brown horn without a driver. Also included was in incomplete 1929 Airzone portable receiver. Actually, the word portable should be used with inverted commas, because portables from the 1920s era were fairly hefty items. Adding a carrying handle doesn't necessarily make something portable! The other receivers consisted of two 3-valve regenerative types (detector plus two audio); a 4-valve regenerative type with a neutralized radio frequency stage and two tuning dials; and a 5-valve TRF with two neutralized stages of RF amplific·ation and single knob tuning. All were battery operated and used either 4V or 6V triode valves. Dealer prices If these receivers were to be found in an antique shop , one would have to spend a couple of thousand dollars or so to purchase them, regardless of their mediocre condition. Personally, I believe that the prices . dealers place on old radio receivers far exceed their worth and that their true value is generally about one third the asking price. I don't pay dealers' prices for my radios unless it is for something really exceptional. Accordingly, I offered $600 for this collection of dusty relics and my bid was accepted. $600 was either the best or only bid that had been offered. I believed it was a fair price considering. nothing was clean, tidy, or in working order. Most of what was on offer needed the full restoration treatment before any of it could be considered valuable. Returning for a moment to antique dealers' prices, I find it incredible that when I sell a fully restored radio I cannot obtain what a dealer asks for ...;, Back view of the home-made 3-valve chassis. There are plenty of problems here, including three useless valves, two open circuit audio transformers & a broken dial, to name just a few. This 3-valve receiver was built by "Golden City Radio" ofBallarat, Victoria. It is very long for a 3-valve set & has battery storage space at both ends of the cabinet. a similar set in unrestored condition. In many cases, the dealer's set doesn't even work. Either I'm too cheap or antique dealers are too dear. I think the latter is more likely correct! However, in all fairness, one must take into account the time and travel costs involved in going to auctions, garage sales, or whatever. This must be added to the price of any collectable item and the rarer the item, the more time it takes to find. If you are not prepared to do this, then the antique dealer will do it for you - for a price; his price! Only a few days ago, I had an antique dealer complain to me that I hadn't bought a radio from him for at least a year. My reply was "when you have something I really want and it is realistically priced, then I will buy it!" Because I am interested in old radios he expects me to buy every receiver he has in stock. This same dealer had on display a mid-1950s 4-valve Radiola with a cracked plastic cabinet, odd control knobs and a price tag of $89.00. This example should convey the message I am trying to get across about dealers' prices being too high. Now then, let's get back to those old receivers. Really, there is only one good one among them and that is the 5-valve TRF set. Like so many early radios, it has no maker's name but it must have been better than average in its day because it is fitted with single knob tuning. Most 5-valve TRFs from that era have three vernier dials driving three individual tuning capacitors. Like many TRF receivers, it is a straight set with no regeneration. Regeneration can shift the tuning of the detector circuit and is undesirable with a ganged tuning capacitor unless one section can be trimmed from the control panel. Of the other sets, one of the 3-valvers is a home-made affair with two dials on the front control panel. Only one is used for tuning; the other is used as a vernier for the reaction control. This little home-built set is unique in a rough sort of way, for its cabinet has been fashioned from the proverbial packing case. Although my first impression was "yuk!", I have since developed a liking for this scruffy little packing case special. It truly represents the typical home-built receiver of the 1920s, whereby the overall expense of the outfit was kept to an absolute minimum. Its only aesthetic feature is three little wooden bobbles attached to each side of the front control panel. The other 3-valver is a large commercially made receiver built by "Golden City Radio" of Ballarat, Victoria. As with most 3-valve sets from the 1920s, it is about as basic as a regenerative detector receiver can be. These radios were produced in quantity for the budget end of the market. Three valves gave sufficient power for reasonable loudspeaker operation on local stations. Unfortunately the dial on the front control panel had been smashed. As luck would have it however, I have an The "Golden City Radio" receiver has a smashed dial - just one of the many problems in this particular set. Fortunately, a spare dial is available but general restoration work on old receivers is difficult due to lack of spares. MAY 1993 57 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 rather uninspiring control panel belongs to the 5-valve TRF receiver. The controls are, from the left: volume, tuning & filament rheostat. The latter control also serves as an on/off switch. * High quality * Hold up to 14 issues * 80mm internal width * SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A11 .95 plus $3 p&p each (NZ $6 p&p). Send your order to: Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. · Use this handy form l ----------Enclosed is my cheque/money order for $_ _ _ or please debit my o Bankcard O Visa O Mastercard Card No: Card Expiry Date _ _/_ _ Signature_ · _ _ __ __ __ _ Name _ __ _ __ _ _ _ __ Address _ __ __ _ _ _ __ _ _ _ __ _ _ P/code_ __ ., _ _ _ _ _ _ _ _ _ _ _ ,1 58 SILICON CHIP These four horn speakers came with the old receivers. A lot of work is required to restore them to working condition. identical unit that can be used as a replacement when I finally get around to restoring the set. Another problem with this particular receiver is with the top of the cabinet lid, for it has been subjected to a massive paint spill. There is a scab-like blob of lacquer on the lid which will take quite a bit of work to remove without damage. Finally, there's the 4-valve TRF set with the single RF stage. While this unit appears to be commercially made, once again there is no brand name. Some of those manufacturers of old were not very proud of their products. It is a poor state of affairs when they were too ashamed of what they made to put their name on it. Or was it was a way around paying royalties or taxes or something? Or maybe the sets sold so fast that noone had time to fit a badge or nameplate! This little 4-valver is a fairly compact outfit and its cabinet has double doors underneath the receiver to house the batteries. Receivers with self-contained batteries were a good deal tidier than those without. Batteries strewn all over the floor, together with their connecting wires, must have been a great annoyance during the early days of radio. Mains-operated sets must have been a great relief after the humbug of battery power. KALEX The UV People ETCH TANKS • Bubble Etch • Circulating LIGHT BOXES • Portuvee 4 • Portuvee 6 • Dual Level TRIMMER e Ideal PCB DRILL • Toyo HiSpeed MATERIAi-$ The 4-valve regenerative receiver was commercially made & has a stage of neutralized radio frequency amplification. Note the battery storage space at the bottom of the cabinet. All the horn speakers were fairly sad looking, especially an Amplion "Senior Dragon". This particular horn speaker has an oak flare and, like most timber flares, has not survived its near 70 years very well. It has several splits and chips and the rubber parts have also gone out of shape, a common problem with old Amplions. Another unit is a Claritone, a horn speaker that has quite a large flare. Once again, it is only in fair condition and is rusting due to peeling nickel work. The big Brown horn is quite a stylish shape and should restore fairly well, although it will require a full repaint job. Do anyone know where I might get onto some "Brown" transfers? Every one of the horn speakers re- quires the full restoration treatment and that includes a rewind of the driver coil in some instances. However, it was not a bad collection of junk for the price, even though very little of it is in good condition and there is a lot of work to be done. Valve checks This is a project for the future. So far, I have done nothing other than check the valves - and that was a somewhat disheartening experience. Out of 19 valves (including the Airzone portable), there was only one good one. Some base pin resoldering may retrieve some of them, otherwise I will be scrounging around for some old 4V and 6V triodes. But that is what vintage radio is all about - searching, scrounging, find- This wiring mess once formed the battery leads of the 5valve TRF receiver. A complete rewiring job should solve the problem. The two sockets are for the speaker leads. • PC Board: Riston, Dynachem e 3M Label/Panel Stock • Dynamark: Metal, Plastic AUSTRALIA'S N0.1 STOCKIST * - * I ZI 40 Wallis Ave, East Ivanhoe 3079. Phone (03) 497 3422, Fax (03) 499 2381 ing and restoring. There would be little satisfaction if every set was in perfect working order, although a good one now and then would be nice. Every time I add an old 1920s radio or horn speaker to my collection, I reckon that it will be the last I will ever see. I have said that a few times now but something else always seems to come along. It just goes to show that there are still odd bits and pieces of 1920s equipment out there. It is only a matter of finding it! SC These bobbles on the home-made 3-valve TRF receiver did little to improve its appearance & certainly did nothing to improve the set's performance. MAY 1993 59 _ALTR.C>N"IC COMPONENTS e e ~ LJAfn L,vv } L,1,, AUSTRALIA WIDE ALTRONICS 24 HOUR EXPRESS DELIVERY 'Our customers are often amazed at the speed and efficiency of our Jetservice Courier delivery. Phone your order Toll Free 008 999 007 and presto we can deliver your order next working day (country areas allow an extra 24-48 hours). Our famous 14 day satisfaction money back guarantee protects your hard earned $$$' s should ever a purchase be unsuitable for your needs. I invite you to try Australia's best electronics phone order service soon.' Sound Effect Mixer ust arrived these mixers are fantastic for · os, home hi-fi's video editing etc. eatures: 5 channels with 8 inputs (first 3 channel e switchable between 2 inputs) • Input acilities include: DJ mic, mic, phono 1, hono 2, line 1, line 2, line 3, line 4 • All · ass and master volume controls allows y tween phono 1 and 2 • Cue monitor s pedal effects circuit s' · lephone and st A 2530 Video to TV Transmitter Kit Fluorescent Light Inverter Kits Stereo Disco & 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 as fluorescent light offers 2 big advantages over normal incandescent lights. Namely more even 360" light spread and low current drain. Two kit versions to choose from 16W and 20 to 40W. 219·00 l!.D.!:e ~l!.!lu~x:.:!e!:Z..6_C --t.h~a:::n~n::i.e .:::l::\,...:::::::.Ca.L::.::....___'.=============~ Mixer with Echo and Sound Effects K 6350 16W Version $35·95 K636020-40WVersion$43·95 tance meter is designed for the workshop or laboratory. It can measure capacitance from 1pF up to 9999µF in seven ranges with an accuracy of better than ±1 %. An over-range LED flashes whenever the capacitance value is too large for the range selected. a Ideal for automotive terminals and connectors. Crimping range 0.25mm - 6.0mm. 95 T1552 $54· Super Heavy Duty Will Last a Lifetime! Automaticlll ~~= Wire Stripper The jaws on this stripper automatically adjust to suit any size cable up to 4mm. Ideal for repetition cable stripping for the professional or enthusiasts workbench. .SO Strip Those Cables T 1515 Quickly & Easily! $24 K 2524 Normally $119· you to customise your sound system in your car or at home. The circuit sirrtply connects between the audio source and the amplifiers. There are two outputs one for bass and another provides signal for the upper range. Thus each amp is dedicated to a frequency range (i.e. one for bass, one for midrange and treble). Because no passive crossover is required in the speaker one per channel is required. Operates on + and - 15V rails. The result is much better sound with less distortion. 95 K 5570 Improve Your Hi-Fi's $19· Sound Quality! L-----========::....j DiscoLite Chaser & Colour Organ Kit (SC July-Aug '88) The Discolite flashes party lights on and off in beat with music from your amplifier. Features: • 4 light channels controlled by 4 separate audio channels • Forward reverse and autoreversing chaser patte~ • Simultaneous strobe on all four channels • Alternating light patterns • Music modulation available on chaser strobe and alternate patterns • Inbuilt microphone or direct inputs for beat triggering or audio modulalion of lights • Sensitivity control • Individually pre-settable sensitivity levels for each channel • Front panel LEDs mimic light display • Altronics Kit pre-punched and silk screened 50 K 5805 $159· This Month Only 95 $99·00 95 $49 Low Cost Inductance Adaptor Kit $599·00 L...;::::c..====="-===-_;,.,;,_:=i1 ---------------.-----~;::;_..::;_..i.::;4-.:..::,:...;:,.,__~ (SC May '90) This attractive 4-digit capaci- Heavy Duty Crimping Tool K 5860 Normally $74· This Month Only 4-Digit Capacitance Meter Kit 6 channels with 10 inputs. Inputs include: mic 1, mic 2, phono 1, phono 2, phono 3, line 1, line 2, line 3, line 4 and line 5. Two seven band graphic equalisers and master controls allow precise sound refinement. Features sound effect generator (simulates storm, telephone, machine gun, siren, shooting, ambulance, laser and bombing) and echo control. Twin LED VU displays for master output. A must for the serious DJ, sound technician or hi-fi buff. A 2540 This kit enables you to transmit TV signals from the UHF output of your VCR to a second TV set in the house. The kit is complete with box and has a range of about 20 metres. Requires 12 Volts DC. (pictured without case-included). (EA Dec'92) Measuring the inductance of wirewoW1d components has not been easy until now, but here's a handy adaptor unit. Simply plugs plugs into a standard digital multimeter. Provides two direct-reacting measurement ranges. 95 K 2560 -$39· Ni-Cad Battery Discharger Kit (SC July '92) Designed to rid your nicad batteries of the memory effect and regain full recharge potential. It discharges your nicads correctly to enable a full recharge. Suits most battery packs. Great for mobile phones, battery drills, toys etc. 95 Rejuvenate Those Old Ni-Cad K 1640 $24· Batteries to Their Full Potential! The Powerhouse 1200W Inverter Kit (EA Feb '92) This Power Inverter will provide all your power requirements from a heavy duty 12 or 24V battery. Using the latest Mosfet outputstageandtoroidaltransformerthis inverter is both efficient and will deliver high surge currents. The Powerhouse has been designed not only for rugged bullet proof operation but for ease of construelion, two PCB' s hold all circuitry with one inter-connecting cable. This kit comes to you in a fully drilled, pre punched chassis complete with silk screened front panel. Assembly of the kit is simplified as the majority of components mount on a single PCB. Thus virtually eliminat-------ing all external terminations. Suitable for use in camping, boating, fishing, mining, farming, remote settlements etc. ' K 6790 Kit Version Normally $799·00, This Month Only $749·00 K 6792 Fully Built & Tested 12V Input $ K 6793 Fully Built & Tested 24V Input 999 .00 PHONE ORDER - FREECALL 008 999 007 AUSTRALIA -WIDE e ~ L...iAj/l l..,vv J L,i, e .ALTR. C> ~ I C COMPONENTS CC V3242 Fax/Modem CD Cleaner We are clearing out our CD Cleaners. These cleaners use the correct motion fo r removing small surface scratches and general d irt and grime. 95 A 9220 NORMALLY $17.95 This Month Only $7 up-t O-Date WorIds Transis tor, Diodes, ------------t.-"':;;...----1 Thyristor IC's Comparison Tab le Books These extremely compact books gives a brief descrip tion, specifications as well as equivalents for transistors, diodes, thyristors and IC's. Excellent reference books for professionals and hobbyists alike. Each contains hundreds of pages with thousands of components. $19·95 Transistors, Diodes, TI1yristors & IC's 95 B 1275 A- Z Transistors $18· B 1280 Q - µ Transistors $18· 95 B 1270 Ideal R eference Books for the Hobb yist & Professional Buy A ll 3 for $49.95 & SA VE! The Comma 3242 is an integrated, high performan ce modem that supports all popular CCITT and Bell modem standards, including the newest standard, CCIIT recommendation V32bis for dial up communica tions at 14.4K bit/ s and all CCITT standards fc,r full FAX operation. The modem can operate fullduplex and half-duplex in synchronous and asynchronous data format at 9600, 7200, 4800 and 2400, 1200 and 300 bit/s. '>end • , trnn h, n, The Comma Fax/Mod em opera tes like a fully featured fax machine. Your faxes can now be sent d irectly from your PC without having to print them first.You can view incoming faxes on-screen or print them using a standard dot matrix printer. Only print the faxes you want to keep - just think of the savings on expensive fax paper. rime S.n ing. The Comma Fax/Modem will also receive faxes in the background while you continue to work. When faxing out, the Fax/ Modem will redial an engaged number so you can be sure your faxes are sent. The software also automatically keeps a complete log of both incoming and outgoing faxes. Also supported are cover pages, broadcast faxes, and schedul~:i i: ~_software keeps a database type register of regularly used fax numbers for easy mouse support. Mlw11 D 1595 $699-00 while protecting components from static damage. Fantastic for assembly, service work and enthusiasts alike! T 4001 $14·50 1----------- ----UHF Microprocessor Controlled Wireless It' • model as well. The Comma Fax /Modem is a fully AT command compatible modem. Features include V22/V22bis standards (V21/23 is an option) both 1200 and 2400 baud rates are supported as well as auto answer, dialling and discon. nect. You will find it compatible with all popular commu- Turn Your PC or Mac into a nication software. Fax with This state-of-the1 , '>oitw <- With each modem you will receive the QL2 Art Fax/Modem! Fax/modem software featuring both pull-down and Security System Why Pay A Commercial Security Firm A Fortune To Wire Your House or Office. This Fantastic System Installs In Au Hour or Two Aud Uses No Wires Passive Infra-Red Lite Aide Floodlight Control How often have you thought there could be a prowler outside your door? Install a Lite Aide and (once armed) any "guest'' will be floodlit when detected by this highly sensitive Infra-Red Detector. The Light Aide detects a moving person or vehicle by comparing the background temperature with a rapid change of temperature across the detection beams. So when Lite Aide detects movement across the coverage area, it will turn on the floodlight(s) for 10 seconds to 15 minutes as pre-adjusted. ===============;:::.j s 5350 Was $49· 13.SV 1A UPS Designed for critical applications where it is important that products remain operational during mains failure, this UPS (Uninterruptible Power Su pply) will supply 12V at 1.2 Amps via its internal inbuilt sealed lead acid battery even when the mains has failed. Ideal for use with alarm systems etc. Anti-Static Wrist Strap 95 , Now Only $39·95 Cheap Security! operation of the system one of the great features is its application with rented or leased premises - let's face it, money spent on This amazing model features just about everything you could imagine! Multi-function installing a w ired system in your home or keyring remote control will arm and disarm alarm (and activate central locking if fitted), office, facto ry, etc is irrevocably lost when chirp the horn, turn on the car headlights, panic and even open the boot (ii actuator fitted). you move on. With this system you simply One remote can control two alarms (in two cars). take it with you. Ultra high-tech and push Other fea tures include starter inhibit, valet mod e, button operation makes this unit a breeze to central locking interface, flashes car indicators install and operate. Features 6 sectors plus 2 when tripped, auto reset, user programmable x 24 hour fire and tainper circuits. The options plus much more. S 5240 system incl ud es th e main controller, 00 S 5230 Normally $249· $50 Off 1 passive infra red movement detector, 1 window or d oor reed switch, wired siren, M_ 9090 _ _.;..._ _ _ _ _ _ _ _ _ _--I This Month Only ·OO Amazing Value! power supply back-up rechargeable battery, and a special personal remote control. All sensors are radio transmitters which means no wiring is necessary (except for the plug Connects easily into most car or house alarm systems. pack and siren). The whole system is coded New weatherproof This self contained compact unit delivers a massive so it can not be interfered with and can be design ideally suited t 120dB of deafening sound pressure once activated. It changed any time by the owner, Each indioutdoor applications. connects simply via 3 wires to any alarm system (car or vidual sensor can be easily set to operate Blue lens. 1 wa tt outp house) that has an output that is normally negative (or any sector. The main controller utilises the Uses Xenon tube for low). When the alarm system is activated and the outlatest EEPROM technology which means high energy flash. Fla put goes positive (or high) the siren will sound. The things like selecting user on / off codes, isorate approx 75 per siren will also operate if the wires to it are cut. Hence it adds extra security to your system lating sectors etc. are a breeze. Includes a minute. 12V DC 150 if someone tampers with it to disable it. Simply armed and disarmed via inbuilt key switch. myriad of other amazing features, too many 53hmm. S 5235 N ormally $69·95 to mention. 50 . $59·95 Complete system includes: s 5445 This Month Only 1 x Control Panel 1 x Passive Infra Red ;.....,:;..._....;._➔_4 _S _e_c_t_o _r_A _l.,.a rm -C -o-n tro""l"""" P-a -n -e-l-------~iiiii"i-l Detector-Transmitter 1 x Door-Win dow reed II!! Switch-Transmitter 1 X Hand Held remote For Commercial and Residential Premises. 4 independent secControl-Transmi tter 1 x Horn Speaker - 10 tions accept N .0. and N .C. sensors. Any sector can be individualwatt-wired 1 x 240V AC adaptor 1 x 1.2Ah Incorporates Pulse ly isolated, (e.g. when at home you may want to turn on perimeBack-up Battery 1 Count Triggering ter sensors, allowing movement inside). User selectable 4 digit x Set of batteries Extra Sensors etc. Using the lates t technolpin number allows you to arm and dis-arm the alarm via digital for all transmitters Available Separately ogy this compact Passive keypad. Sector 1 - 24 hour (Panic and Tamper), Sector 2 - Instant, Infra Red Detector S 5240 Complete System Price Sector 3 - Hand-over FeatUie, Sector 4 - Delayed. Features du al (P.I.R.) fea tures Pulse intelligent siren drivers (i.e. if one speaker wire is cut the other Only $ 6 7 9 00 Count Triggering which will sound). Constructed in sturdy steel case. Requires l .2Ah gell 00 This Month Only virtually eliminates false cell fo r battery back-up (S 5065), 16V AC plug pack (M 9025) and alarms. 8 ohm horn speakers (C 2015). ALTIWMCS 1993 RETAIL CA TA LOGUE 00 S 5302 Normally $62· 50, If you haven't received yours call us on S 5485 Normally $249·00, This Month Only 00 008 999 007 for your free copy! This month Only ~-~~~ $69·95 Mini Strobe Signal Lamps High-Tech Remote Car A arm $199 =====-t Satellite Suen $19· p ______ _ I_ ___ ass1ve Movement $599· $49· $199· PHONE ORDER - FREECALL 008 999 007 .ALTR. C> N"I C::: COMPONENTS Aviation Headset It was no t to long ago w hen spend- ing $450.00 on an Aviation Headset e ~ }\..," e A US TRALIA WIDE L..JAYI \..,IJIJ Digital Voltmeter 1000's Sold Across A11stralia Includes 2 Year Warranhjl This well designed LCD module w ill take care of mos t of your requirements of cligital voltmeter displays. w as no t uncommon. A ltronics Voltage range and decimal place o ptions are easily changed all that when we released our C 9070 Aviation Headset for under $189.00. Now with the edition of the flexible boom unit and helicopter version (fitted with a Nato plug) our headsets have gone from strength to strength. Add lo this configured by PCB links. Small, compact, rebable and comes compl ete w ith plas tic surround to give a professional finish. Specifications: Digits; ... ........ ........ ....... ,......3.5, 13nun Height Ranges:.... 200m V, 2V, 20V, 200V, 1000V DC Input lmpedance:......... ................. .... .... lOMQ Power Supply: ....... 9V DC Over-range Indicator: ................................. '1' enhanced microphone, improved lead shielding and headband comfort these headsets must be the best value for money in A ustralia! $189·00 00 C 9073 New Flexible Boom Model $22500 C 9072 New Hebcopter Model $249· C 9070 Stand ard Model Decimal Place: ............. ... Variable Accuracy; ............................. +/-0.5% (2 cligit) Q 0560 Alphanumeric Dot Matrix LCD Module Aviation Push-to-Talk Switches Includes quabty vekro strap and simple push-button opera tion. $29·95 icron Sure Shot Desolderi C 9090 ----------------------------------1 This compact LCD module has 96 inbuilt ASCII characters and 92 special letters which can be clisplayedon a 16characterby 2bne screen. The module will hold the current input on the display using its own built in memory, thu s making it very easy to drive. Some possible applica tions could be with in fax machines, measuring instruments, tele phone This Module can be Programmed for applications or any other area where m achine Personalised Messages for Your Car, user feedback is required. Exclusive to Altronics in Australia. This stand alone, fully self-contained desoldering tool makes it a breeze to remove components from any PCB. Even double sided, through hole plated boards. All ii needs is a squeeze or h-vo on the trigger and the component virtually falls out. Features; • Totally sell contained • 2 7299 $3 5.00 Alarm System etc. etc. Lig ht and compact • Anti s tatic tip • Easy to use • Simple to clean and maintain • Variable tip temperature. The Sure Sho t generates a high speed vacuum every time the trigger is squeezed. This vacuum causes Digital Multimeter & LCR Includes CarnJ Case Meter the molten solder to flow into the collection reservoir contained w ithin the unit. Here the molten solder solidifies into small particles. With its inbuilt variable tempera hue control the Sure Shot is ideal for single Universal Multimeter Carry Case Q 1052 This digi ta! meter sided, double sided and through hole plated P.C.B.'s. With just a couple of ~ - - -- - tests in addition to standard mul- squeezes of the trigger all h oles are left sold er-free for easy removal of the component. T 1270 $39·95 timeter ranges, capacitance and indu ctance, $349·00 enabbng you to test a w ide vari- ety of components. lnclispensable fo r the design engineer, technician and enthusiast alike . swi tch and ' -- - -- - - -- able temperature control, LED bargraph 24 Range Digital Multimeter : ;\': ::~; ~: : ::P~: g: i :: c:dl: :!er heavy duty iron clad tips etc. Range of tip ! ~~i:::!~e~~~racy Current Check. 3.5 ----' a light & heavy load switch with metered output. Works well with most electrical Features vari- e quipment. M 8120 NORMALLY $249 00 This Month Only $199·00 sizes available . $l 6 .9, 9 Suits Hobbyists digit. Ranges include and Professionals AC & DC voltage, AC Alike! & DC current, resis======S;;;a;;;v;;;e=Z;;;Oo/i;;;o======---1---------========-I tance, diode check, Fantastic for Camping, Farmers etc. High Quality T0-3 Transistor Mounting Brackets T $l 49 This Month 2440 •p M U 1tlUrpOSe Electrical Tester This fantastic gad get will test a myriad of heavy duty 3mm aluminium. Pre-drilled fo r four T0 -3 transis tors and three mounting bolts. Dimensions 152w x 42d x 23h mm aj:,prox. Fantastic for power supplies, amps etc etc. Sorry Not Available from Altronic Re-Sellers HR0595 $frOO Hurry Stocks Limited! electrical and e lectronic components. It is simple to operate and is sure to am aze you with it' s uses. Best of all, it' s priced to make it a must for every techni cian, electrician and enthusiast. Tests continuity / resistance (100MQ, 50MQ and 5MQ ranges), with buzzer and / or LED indication. Dead easy to use. Will check fuses, light bulbs, wiring, elements. spea kers, diodes/LEDS, transistors, transformers and the list is endless. Q 1250 Amazing Low Price Includes frequency and capacitance ranges. With the addition of a transistor check etc. ::1:.°;~%!,~:e~ this meter would have st would have to one of available today. Q 1035 Q 1030 Q 1040 Pro tecti ve Holster to Suit $15.95 $99·00 Q 1040 Protective Holster to Suit $15.95 from ultimete With Frequ ency M easurem ent and Capacitance Meter. 95 $17· the most useful DMM's available today. $169·00 M§i<at>M Auto Ranging 3.75 Digit Digital Multimeter Triple LCD Display Includes 2 Digital & 1 Bar Graph. This incredible multime ter would have to be one of the most com- prehensive on the market today. It is capable of doing all the normal Ill voltage, current and resistance readings, as well as capacitan ce, frequency, minimum and m aximum sampling, relating measurements, storing previous readings, limit setting, signal transistor gain checki.ng and is full auto-rangin g. Ql03s$199·00 . - I 1 Q 1040 Protective Holster to Suit $15.95 PHONE ORDER - FREECALL 008 999 007 e A US TRA LIA WIDE C 6170 yI Cat No. C 3045 C 3055 C 3060 C 3065 C3070 C3075 Ideal Replacement Tweeter, or for That High Power Speaker Project! Piezo Design Means no Crossover is Required - Virtually Indestructible , A LTR. C> ~ I C COMPONENTS e 2 Co Motorola KSN1151A/1142A P 3310 Pack 10 Sets P 3312 Pack 100 Sets Il l Was tion. Dimensions:..... . ........... 265 x 110mm Frequency Response: .... 1.8kHz - 30kHz SPL: .............. ....................92dB (2.83V /l m) ...... 75w nom, 400w max P 3000 9 Pin Male $1.50 P 3010 9 Pin Female $1.50 P 3100 15 Pin Male $1.75 P 311015 Pin Female $1.75 P 3200 25 Pin Male $1.95 P 3210 25 Pin Female $1.95 P 3070 15 Pin D9 Male $4.35 P 3080 15 Pin D9 Femle $4.35 P 3090 9 Pin Ea This Month $4.95 $4.15 $39.95 $34.95 Was ISaveUpTo20% I Horn part no. KSN1151A, driver part no. KSN1142A. PiezoHorn speaker suited to Hi Fi, PA and sound reinforcement. With ·built-in protec- Was This Month $27.50 $16.50 $29.95 $17.95 $29.95 $49.95 $69.00 $41.40 $99.00 $59.40 $129.00 $77.40 Watts RMS Watts Max Size 6.5" Midrange 30W SOW 6.S"Woofer/Midrange 30W SOW 8" Woofer 60W 100W 10" Woofer 60W 100W 12" Woofer 100W 150W 15" Woofer 120W 200W =========4 & S ~kL Ea This Month $1.35 $1.35 $1.60 $1.60 $1.75 $1.75 $3.95 $3.95 Ea l Oup $l. 20 $1.20 $l.40 $l.40 :!: ~ $3.50 $3.50 P P P P P P 3020 9 Pin Male 3030 9 Pin Female 3120 15 Pin Male 3130 15 Pin Female 3220 25 Pin Male 3230 25 Pin Female f, Ea This Month $2.00 $2.00 $2.25 $2.25 $2.65 $2.65 Was $2.25 $2.25 $2.50 $2.50 $2.95 $2.95 Ea 10up $1.80 $1.80 $2.00 $2.00 $2.40 $2.40 Great for working on the boat, car, farm TV Ea This P 3040 9 Pin Male Ea This Ea P 3050 9 Pin Female Was Month lOup P 3140 15 Pin Male $1.95 $1.80 6 $l. 0 P 3150 15 Pin Feinale $2.20 $1.95 $l.80 P 3240 25 Pin Male $2.50 $2.20 $2·00 P 3250 25 Pin Female Designed to house amplifiers, inverters, power supplies micro-processor equipment etc. Built-in mounting posts for PCB's, transformers etc. Ventilated for efficient air-flow cooling. Extra tough, Super finish front and rear panels. Pictured battery for size comparison only. 95 H 0490 Case T 2720 Needle Nose Pliers 95 ALL NORMALLY $9· ea This Month Only e l,;IJIJ These fantastic speakers are ideal replacement speakers or for your own speaker design Features extended bottom-end frequency response performance and cabinet size reductions for a given level of performance. The lightweight plastic cones offer levels of performance above that of conventional cardboard cones. The cone is more rigid and does not ''break-up" (flex) as much as its counterparts. - $39·95 ~A Pol Motorola KSN1177 A Piezo Twin Tweete1 NewTwin Drive bullet provides outstanding acoustic performance. Rated tolO0Watts. ~ J l,;,., $29· $7.95 ea 174 Roe t. Perth .A. 6000 Phone (09) 3281599, Fax (09) 328 4459 Cl- P.O. Box 8350 Stirling Street, PERTH W.A. 6849 STANIHRil Dl·II\H') '.\ ( <H \ ,I $3.50 to 500gms, $5.50 500gms -1 kg, $8 1kg-5kg AUSTRALIA WIDE-We process your order the day received and despatch via. Australia Post. Allow approx 9 d ays from day you post order to when you receive goods. OVER. IGllT JfTSLR v lC. E Up to 3kg is $10.00, 3kg to 5kg is $23.00-We try to process , ,I -All orders of l0kgs or more must travel Express Road-Please allow 7 days for delivery. $12.00 to lOkgs. $15.00 over lOkgs. ( I -As with virtually every other Australian supplier, we send goods at con- signee's risk. Should you require comprehensive insurance cover against loss or damage please add $1.00 per $100 of order value (minimum charge $1). When phone ordering please request ''Insurance". ", -Bankcard, Visa, Mastercard Holders can phone order toll free your order the day received and despatch via. Overnight Jetservice Comier for delivery up to 4pm Eastern Standard Time. Remember with our Overnight Jetservice we deliver next next day Country areas please allow additional 24-48 hours. day. ALTR0"1ICS RESl· I l. I{', Chances are there is an Altronic Reseller right near you-check this list or phone us for details of the nearest dealer. Blue Ribbon Dealers are highlighted with a• These dealers generally carry a comprehensive range of Altronic products and kits or will order ru1y required item for you. WA - COU r BP Electronics • . ........ (098) 412681 Micro Electronics ........(098) 412077 BUNBURY Micro Electronics ... (097) 216222 ESPERANCE Esperance Comm. . ........ (090) 713344 MANDURAH Lance Rock Retravision ....... (09) 535 1246 PORT HEDLAND Ivan Tomek Electronics ........ (091) 732531 ROCKINGHAM TVJoe's.. .......... (0~)5271806 ALBANY NT ALICE SPRINGS Farmer Electronics DARWIN Ventronics ..... .......... (089) 522388 ......... (089) 853 622 VIC-C TY BORONIA CHELTENHAM COLLINGWOOD CROYDON FOOTSCRAY PRESTON COUNT All Electronic Comp .............. (03) 6623506 TECS............... .................... (03) 6706474 R~oss Electronics• ....... (03) 7622422 T · g Electronics ................ (03) 5842386 Truscott Electronics•... ... (03) 4198208 Truscott Electronics• ··········(03) 7233860 BAIRNSDALE LH & LM Crawford ...............(051) 525677 ENFIELD Aztronics• BAL LARAT Ballarat Electronics ................. (053) 311947 MILDURA Pullman Auto ....... ...................(050) 232882 Eyre Electronics ........... ......... (086) 454764 SHEPPARTON Andrew Guyatt Elect. ............ (058) 219497 WHYALLA WARRNAMBOOL Koroit Electronics. ..... (055) 627 417 HOBART George Harvey • ................. (002) 342233 Delsound PL ... ....... (07) 8396155 LAUNCESTON George Harvey• .... ............. (003) 316533 WESTEND B.A.S. Audiotronics... ... (07) 8447566 ( David I-Jail Elect.• .................(07) 8082777 WOODRIDGE A-One Electronics .................. (02) 2674819 N David Reid Elect. •················(02) 2671385 GLADSTONE Gladstone Elect. Services ....... (079) 724459 Chantronics .. ............(02) 6097218 Electronic Enterprises ............ (079) 726660 SMITHFIELD MAROOCHYDORE Mais Electronics• ....... (074) 436119 TOWNSVILLE Super Solex •······ .......... (077) 724466 COFFSHARBOURCoffs Habour Elect... ... .......... (066) 525684 A - CITY NEWCASTLE Novocastrian Elect.Supplies .(049) 621358 Force Electronics • .. .............(08) 2125505 BRIGHTON Force Electronics•....... .(08) 3770512 WARNERS BAY Vilec Distributors ................... (049) 566792 WINDSOR M & E Elect. and Comm ....... (045) 775935 CHRISTIES BEACH Force Electronics• ...............(08) 3823366 WOLLONGONG Newtek Electronics• ........... (042) 271620 HILL ~:~:~:::~ : :: Vimcom Electronics ..............(042) 284400 LONSDALE Force Electronics•... ..... (08) 3260901 WOYWOY Alphatran Electronics ........... (043) 434919 ~;!t~~~fe!~ci~;·.::::::: :Jg~i :~mr:~~~ ~~~~: _Jg~i ~mi~~ PHONE ORDER - FREECALL 008 999 007 Alphan11meric LCD Demonstration Board Using an alphanumeric LCD panel is not as hard as you may have thought. In this article, we show you how to interface one to a PC printer port. By DARREN YATES Over the last few years, the cost of alphanumeric displays has dropped dramatically. That's hardly surprising, considering they are being used increasingly in consumer goods as the push continues for "smart" appliances. Most of these displays are controlled. by _microprocessors and are designed to make complicated equipment easier to operate. Items such as microwave ovens, fax machines, CD 64 SILICON CHIP players and car stereos now use alphanumeric panels to display options and commands to help the user achieve the desired result. Alphanumeric LCDs are available in many shapes and sizes but one of the most cost-effective types is the 16 character x 2 line display that's used here. It requires only 11 connections - eight bits for data (which can be reduced to four if necessary) and three lines for control. It runs off a SV DC supply and sells for just $35, making it perfect micro- . processor-controlled projects. Circuit details The LCD module contains two microprocessors and that's about all there is to tell. These can be easily described as the two black blobs on the back of the PC board. Apart from the display itself there's nothing else, it's that compact. · Fig.1 sh_o ws the simple circuitry that goes with the display. As you can see, it consists of a power supply which uses a 78L05 lO0mA 3-terminal regulator to derive a regulated SV rail. The power is derived from a 9V 300mA plugpack, while D1 provides reverse polarity protection. Since the display requires only about lmA of current, this arrangement is more than adequate. The display contrast is adjusted by means of a 10k.Q trim pot which feeds a voltage into pin 3 of the display. Apart from that, all you need is a male-to-male DB25 cable to connect the display to the PC. D1 1N4004 9VDC 300mA _ __ PLUG-PACK VR1 10k Programming Normally, you would expect to see these displays being driven from a dedicated microcontroller but it's quite easy to get the display to work from your PC's parallel printer port. That's because the display can be easily controlled by programming port A for the eight data bits and port C for the three control lines (note: port A and port C are both part of the one parallel port). One thing that should be noted with the printer ports is that the addresses we've used for port A are 0378 hex (888 decimal) and for port C, 03 7 A hex (890 decimal). All the pins for port A are noninverted; ie, if you set a particular bit to "1", then that bit goes high. However, for Port C, we have used the lower three bits and the first two qie inverted; ie, to set them high, you need to set that bit to "0", not "1". The computer program takes care of all this and you don't need to know very much about computing to get the display to work. For those who are interested in how to program it, the computer program contains documentation which shows the programming sequence. PARALLEL PRINTER PORT (2) o o o - - - - - " - 1 1 vcc VO (3) 0 1 0 - - - - - a t 9 (4) 0 2 0 - - - - -at 2 ROW x16 CHARACTER ALPHANUMERIC DISPLAY AL TRONICS CAT.Z-7299 (5) D 3 0 - - - - - '10LI 11 (6) D 4 o - - - - ~-'1 (7) D5o-----'12at 13 (8) D 6 0 - - - - - - - 'at (9) D 7 0 - - - - - - - ' -14af RS R/W 4 5 E GND 6 (1) S T R o - - - - - - - - - ' (14) A F O - - - - - - - - _ _ . (16) 1 0 - - - - - - - - - - - ' (19-21) GND°"l- 0 I G0 VIEWED FROM BELOW ALPHANUMERIC DISPLAY DEMONSTRATION BOARD Fig.1: the circuit consists of the alphanumeric display module plus a power supply which uses a 78L05 lOOmA 3-terminal regulator to derive a regulated +5V rail. The eight display data lines interface to port A of the parallel printer port, while the three control lines interface to port C. lr, ~·,25-PIN D CONNECTOR Instructions OK, let's get down to the business end of things. The first thing to look at is the three control inputs to the display. They are REGISTER SELECT (pin 4), READ/WRITE SELECT (pin 5) and OPERATION ENABLE (pin 6). The REGISTER SELECT input controls whether you are writing an instruction to the on-board microprocessor (input set to O), or writing data to be displayed on the screen (input set to 1). The on-board microprocessor allows for quite a few different effects, such as shifting characters, scrolling the display left or right, and defining your own characters. We'll look more closely at these special effects later. The READ/WRITE select input allows you to read the current address counter and the busy flag status. They are not often used and are not re- Fig.2: install the links (shown dotted) on the PC board before mounting any of the other parts. The alphanumeric display is connected to the PC board using a right angle pin header which is soldered to the underside of the module. quired to operate the display. The OPERATION ENABLE input is very much like the ENTER key on your keyboard. This pin must be taken high and then low again before the instruction or data is entered in (ie, the operation takes place on the negative going edge of the enable signal). Table 1 is a quick reference chart of the instructions and the corresponding code. By using the printer port, you can program the display in just about any language you like, as long as it has an instruction which allows you to send data to the printer port registers. Let's start by turning the display on. To do this, we initially set port A MAY 1993 65 RS Clear Display 0 0 0 0 0 0 0 0 Cursor Home 0 0 0 0 0 0 0 0 Entry Mode Set 0 Notes R/W 087 086 085 084 083 082 081 080 Parameter 0 0 0 0 0 0 * 1/D 0 DB1 =1: Increment DB1=0: Decrement DB0= 1: Display not shifted s DB0=0: Display shifted Display on/off 0 0 0 0 0 Cursor/ Display Shift 0 0 0 0 0 System Set 0 0 0 0 Set CGRAM Address 0 0 0 Set DDRAM Address 0 0 Read Busy Flag/Address Counter 0 D C B DB2= 1: Display on; DB2=0: Display off DB1 =1: Cursor on; DB1 =0: Cursor off DB0=1: Blinking on; DB0=0: Blinking off S/C R/L * * DB3=1: Shifts display one character DB2= 1: Right shift; DB2=0: Left shift N F * * 0 DB4=1: 8 bits; DB4=0: 4 bits Write Data DL BF The maximum address length is 64 Add The maximum address length is 80 AC DB7 =1: Busy (instruction not accepted) DB7=0: Ready (instruction accepted) Read Data to 12, which is DB3 and DEZ set high. Port C is then set to 7 and then to 3 see Table 1. Because the first two bits of port C are inverted, we need to set them to 1 to get O's at the output. Setting this port to 7 pulls the enable input of the display high and then setting it to 3 0 0--0 Acg Write Data 0 Read Data 0 DB3=1: 2-line display (1/16 duty cycle) DB3=0: 1-line display pulls it low again. If we are using DOS 5.0's QBasic programming language, the code looks like this: OUT 888,12 OUT 890,7 OUT 890,3 If you try this on a 486 machine, 0 :I 0 PC - Alpho.nuMerlc dlsplo.y boo.rd 07106931 0 66 a '--=~-=--=-=__,fllnmm SILICO N CHIP you might find that the change from high to low produced by the last two instructions might be too fast for the microprocessor, so a small delay should added in; eg, by using a FOR .. .NEXT loop. The display initially boots up in an 8-bit data 1-line mode, so we can start entering characters to be displayed o'n the screen almost immediately. One of the best features of this display is that it accepts standard ASCII code. This makes it very simple and versatile to program as it matches the code used in your PC. For example, let's assume that we want the words SILICON CHIP to appear on the top 0 0 Fig.3: check your PC board for etching de(ects by comparing it with this full-size pattern before installing any of the parts. The board measures 128 x 77mm (code 07106931). PARTS LIST Alphanumeric Display Board Demo Software Copyright 1993 Silicon Chip Publications 1 PC board, code 07106931, 128 x 77mm 1 9VDC 300mA plugpack 1 DB25 female right-angle PCB mount connector 1 3.5mm PCB mount socket 1 single way right-angle pin header 2 5mm untapped spacers 2 3mm x 9mm machine screws & nuts 4 rubber feet 1 10kQ trimpot 1 demonstration program (LCD.EXE) - see below COMMANDS (1) Scroll the display right (2) Scroll the display left (3) Enter in text (4) Create a character (5) Turn cursor offi'on (6) Enter in custom character (7) Move cursor (8) Clear display and cursor home (q) quit Command: Fig.4: this is the opening menu of the demonstration program LCD.EXE. By selecting the appropriate number & pressing <enter>, you can enter in text, scroll the display left or right, & create custom characters. Capacitors 1 100µF 16VW electrolytic 1 33µF 16VW electrolytic 1 0.1 µF 63VW MKT polyester Alphanumeric Display Board Demo Software Copyright 1993 Silicon Chip Publications 12:-145 1 Semiconductors 1 2 .row x 16 character alphanumeric display (Altronics Cat. Z-7299) 1 78L05 5VDC 100mA regulator 1 1N4004 diode (01) Where to buy the software The demonstration program LCD.EXE & the source code LCD.BAS can be obtained by sending $10 plus a formatted 5.25-inch or 3.5-inch floppy disc to : SILICON CHIP, PO Box 139, Collaroy Beach , NSW 2097. ♦ 2 3 4 5 6 7 B 0 Move cursor using arrow keys & press <ENTER> to turn the point on/off Press ESC to end editing Fig.5: this on-screen display is brought up by entering <4> <enter> at the opening menu. It allows you to create custom characters by moving the cursor to a desired point using the arrow keys & then pressing <enter> to turn that point on or off. line. The ASCII code for an "S" is either 83 decimal or 53 hex. We don't have to program in hex so we can just use the decimal code. To display the "S", the code would look like this: OUT 888,83 OUT 890,6 FORD = 1 TO 10: NEXT D OUT 890,2 Notice the difference between this and the last section of code. Because we are now entering data and not instructions into the display, the REG- !STER SELECT line is taken high (remember the inversion). The FOR.NEXT loop adds in a delay to make sure that all lines have settled into their final state before w e enter the code. The next letter to be entered is "I". This has an ASCII code of 73 and is entered in exactly the same manner as the "S" except that we now substitute 7~. for 83. Each character code is entered into one of 80 memory locations to give two lines of 40 characters. Because only 16 characters per line can be displayed at any one time, there is an instruction which allows us to scroll the display to either the left or the right. The code for shifting the display one character to the right is 28, while the code for shifting it to the left is 24 - see Table 1. For this project, the basic rule is that if you're entering a command, then you must toggle port C (that's address 890) to 7 and then back to 3. If you're entering data into the display, you have to toggle it to 6 and then back to 2. Each time you execute a shift command, the display is shifted one character in that direction. So in order to scroll the display, you have to enter the code in as many times as you wish to move characters. If you do it indefiMA Y 1993 67 Alphanumeric Display Board Demo Software Copyright 1993 Silicon Chip Publications Alphanumeric LCD Demo Board * * note: first 16 characters only shown. * * press 'x' at line 1 to quit * * Enter in data to be displayed on line 1: Alphanumeric Enter in data to be displayed on line 2: LCD Demo Board Text is entered by pressing <3> <enter> at the opening menu & then typing in the required message. Note that the on-screen text window only shows the first 16 characters of each line, although up to 40 characters can be entered. Alphanumeric Display Board Demo Software Copyright 1993 Silicon Chip Publications COMMANDS (1) Scroll the display right (2) Scroll the display left (4) (5) (6) (7) (8) Create a character Turn cursor off/on Enter in custom character Move cursor Clear display and cursor home Alphanumeric LCD Demo Board (q) quit Command: which of the five dots in that row are to be on and off. Each bit that is set to 1 represents a dot that is on. Again, each row data entry must be followed by port C being fed with 6 and 2 to enter it in. This means that it takes a series of eight instruction sets to create one character. This character is then stored in memory and can be recalled for display by entering O through to 7 for each of the eight characters; ie, OUT 888,0 for character 1; OUT 888,1 for character 2, etc. Construction All of the components for the Alphanumeric Display Demo Board are installed a PC board coded 07106931 and measuring 128 x 77mm. Before you begin construction, make sure that all the tracks on the PC board are OK and that there aren't any defects such as shorts or breaks. If you find any, use a small artwork knife or a small blob of solder where appropriate to fix the problem. The first job is to solder a 16-way right-angle pin header to the edge connector of the display board - see photo. This done, install the 3.5mm socket, the 3-terminal regulator and other components as shown in Fig.2. The PC-mount DB25 socket can then be installed on the board, followed by the LCD module itself. The top of the LCD module is supported on two 5mm spacers and secured using machine screws and nuts. Use the mounting holes at the top of the module as guides when drilling the mounting holes in the PC board. Software Pressing the <enter> key after the second line of text has been entered returns you to the opening menu. The text can be cleared by pressing <8> <enter>. nitely, then the display will scroll across the screen continuously. Character generation The display has a character set which contains 240 different characters but for those who want to "roll their own", there are eight custom characters which can be programmed into the display. To make this easy, our demonstration program (LCD.EXE) has a character generation table built in which allows you to turn any one of the 8 x 5 dots in the character on or off. The 68 SILICON CHIP program then enters the data into one of the eight special character RAMs. To explain briefly how this works, if you refer to Table 1 you will see the instruction SET CGRAM ADDRESS. After bit DB6 has been set high, you can set the CGRAM address counter to · one of 64 addresses. The first eight addresses correspond to the eight rows of the first character, the next eight addresses to the eight rows of the second character, and so on, up to a maximum of eight characters. Once a character address has been set, the data then entered represents As mentioned earlier, a demonstration program (LCD.EXE) plus the source code (LCD.BAS) to go with this project are available from SILICON CHIP (see parts list for details). LCD.EXE allows you to produce all the effects described in this article and is started by typing LCD<enter>. The main command screen is then displayed and this provides a menu of all the possible commands. The software is very straightforward to run and requires no knowledge of how the LCD panel works to get it running. The source code provided runs under DOS 5.0's QBasic. Its main aim is to give experienced programmers a chance to customise the software to suit their own requirements. SC FM TRANSMITTER KIT - Mkll This HIGH QUALITY - LOW COST FM transmitter design doesn't compromise on quality, and it should not be compared to most of the other simple design FM transmitter kits that are currently available. It features pre-emphasis for an improved overall frequency response and better overall signal to noise ratio, a very high audio sensitivity which makes it able to produce useful received outputs with the microphone being placed well away from the sound source, a range of well over 100 metres, etc. But probably the most important feature of this transmitter is its excellent frequency stability: The resultant frequency shift due to waving the antenna away and close to a human body and or changing the supply voltage by ± 1V at 9V will not produce more than 30KHz deviation at 100MHz! That represents a frequency deviation of less than 0.03%, which simply means that the frequency stays within the allocated bandwidth of the tuned frequency on the FM band . It doesn't go noisy and shift to another frequency, but it "stays put"! Transmitter Specifications X-Y LASER SCANNER KIT You could spend thousands of dollars buying commercial X-Y scanners for laser beam deflection. This X-Y scanner compromises by employing two suitable DC motors to achieve good results. With normal levels the motors don't actually spin but simply vibrate around the set position. The PCB and component kit include rectification and filtering (power supply), audio preamplifiers, audio filtering , and two separate power amplifiers to drive the two deflection motors. The scanner is powered by a 16V AC-900mA ·plugpack. In one of the modes of operation the scanner can produce a totally random two dimensional display which is depended on the actual music picked up by the electret microphone. A second mode of operation enables the power amplifiers to be driver from external oscillators and/or pre-taped signals recorded on a stereo cassette recorder. A short form kit of "O ::.&-,rt-., parts is available for Jui~ ~ the X-Y scanner. It ·i;r,;i ~.~ "' ,..Q '"' "' 0 includes a screened -om-.. ~~~ and solder masked 11.J , ~ :, ~ -7 .j-=--.__J PCB and all the on~.. -<J2:c - "' board components, an N f.~~. I !CD'"' electret microphone, ;~rliBl~'~' two motors, and two ~ ~ a -cc-"' F.!li lightweight mirrors. e. ~lJli -ri~r;l8e :U--U •• •• <at>'e rfl ~O I s44 Supply voltage : 6-12V Current consumption <at> 9V: 3.5mA ;;~ =: :~ Qg::: QQ9 240V-16V/900mA AC-DC Plugpack $16 extra. Pre-emphasis: 50uS Frequency_response: 40Hz to greater than 15KHz UNUSUAL ITEMS AND COMPONENTS S/N ratio: Greather than 60dB Sensitivity for full deviation: 20mV Short term frequency stability (see notes): 0.03% PCB dimensions: 26mm X 42mm. Full size PCB overlay is shown below. 20KV PIV-5mA Av./1A Pk. Fast diodes ........ .. ...... ....... ... ... $1.50 ea. 3KV PIV-300mA/30A Pk. Fast diodes ...... .. ........ ... .. ...... ..... 60c ea. 30V.PIV-1A/25A Pk. Schottky Barrier diodes ........ ...... .... .... 45c ea. 680pF/3KV Disc ceramic capacitors ... .. .............. ............. .. . 30c ea. 1000pF/15KV Disc ceramic capacitors ........... ..... .. ................ $5 ea. 0.01uF/5KV Disc ceramic capacitors ..... .... ...... ................. $1.80 ea. Flexible DECIMAL KEYPADS with PCB connectors to suit $1.50 ea. High quality UNIDIRECTIONAL ELECTRET microphone inserts ............. .......................... .. .............. ....... $8.50 Stage quality UNIDIRECTIONAL DYNAMIC microphone inserts ......... ... .... ..... ............. .. .......... .. ............... $9.60 780nM IA diochroic filter (20nM bandpass) for IR detectors ..... $20 FRONT SURFACED MIRRORS: 10mm X 10mm X 1mm ..... ...... $5 20mm X 20mm X 1mm .. .... .. .. $6 200mm X 150mm ................... $8 Construction is easy and repeatable results are obtainable, since no coil winding is necessary. A variable inductor is provided already assembled in a shielded metal can. The double sided and solder masked PCB also makes for very easy construction . OATLEY ELECTRONICS The kit is supplied with a printed circuit board and all the on-board components, a high sensitivity omnidirectional electret microphone, and a 9V battery clip. Telephone: (02) 579 4985 Fax: (02) 570 7910 THE TOTAL COST OF THE KIT IS s11 Or you can purchase three kits for a total of $30. ea. PO Box 89, Oatley, NSW 2223 MAJOR CARDS ACCEPTED WITH PHONE AND FAX ORDERS P & P FOR MOST MIXED ORDERS : AUS I HALIA : S6 ; N.L. (Air Mail) : S10 MAY 1993 69 By FLAVIO SPEDALIERI Build this low-cost mini gas laser separate winding on the primary side of the transformer. It oscillates at about 20kHz or so and steps up the 7.2V DC input to approximately 900V AC. This high voltage AC signal is fed to a Cockcroft-Walton voltage multiplier circuit comprising diodes DlD5 and their associated capacitors. The resulting EHT appears at the catha compact voltage quadrupler to proode of D5 and is fed to the anode of duce an EHT voltage of about 5kV the laser tube via two ballast resistors (82kQ and 33kQ). When the circuit is (before the tube strikes). It can be built first turned on, the Cockcroft-Walton into a length of electrical conduit and used as a laser pointer, or built into a voltage multiplier produces a voltage plastic zippy case for experimental of about 5kV to fire the laser tube and work. establish a discharge current of several milliamps through it. Circuit details Once the discharge current is flowing, the Cockcroft-Walton multiplier Let's take a look at the circuit for can no longer function properly bethe Gas Laser - see Fig.1. The voltage inverter module, based on Ql, Q2 & cause its high impedance is heavily Tl, comes ready-assembled on a small loaded by the laser tube. This high PC board. impedance is artificially provided by the lMQ resistor and the 33pF eaTransistors Ql and Q2, together with Tl, form a complementary . pacitor. So what happens is that the inverter circuit supplies the laser tube switching oscillator with feedback to the transistor bases provided via a via the series path provided by diodes Dl-D5. Even so, the voltage across the laser tube is still quite high, at close to 1000 volts DC. The current through tube while it is operating the tube is set by the ballast resistors . Here's your chance to build a small gas laser pointer for $60. It runs off a 7.2V battery power supply & uses a pre-built inverter module. If you've ever been to a conference or to a lecture, you may have noticed the speaker using a laser pointer to indicate something of importance on an overhead projector. Laser pointers are a great idea because they allow so much more flexibility than before. No longer do you have to stand near the screen to point out something, thereby blocking off the view to half of the people in the audience. In the past, however, the price of laser technology has been pretty steep. But now you can build your own laser pointer for about $50. This project uses a small gas laser, a pre-built voltage inverter module and DANGER! (1 ). Looking directly into the laser could damage your eyesight. Although the tube only has an output of 0.5mW, the concentrated nature of the laser light can damage the retina. Never look into the tube while it is operating - ever. (2). The power supply in this project is capable of giving a severe electric shock. It contains a DC-to-DC converter wh ich steps the voltage up to very high levels. Never work on the circuit while power is applied. In fact, don't even trust the circuit after the power has been disconnected, since the high voltage capacitors can retain a substantial charge for quite some time. 70 SILICON CHIP Construction Before starting the construction, there are a couple of modifications to be made to the inverter module. First, the 240Q resistor (Rl) at one end of the board (next to the two transistors) must be removed and replaced with a lkQ resistor. This will reduce the over- ~ / r ---- ------------- --- ----, 1 L1 *LINK SEPERA TE MOD ULE +1.2vo-<fo--L---.J C4 *R1 I I IOUT I 1 01-05 SxBY309 1k ,-----------+---. T1 I OUT 2 c, ovo------"'--------+-----------......._<iov,___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _-o L - - - - - - - - - - - - - - - - - - - - - - - - LASER POWER SUPPLY Fig.1: the circuit uses a pre-built DC-DC inverter stage to step up the battery voltage to approximately 1000V AC. This signal then drives a Cockcroft-Walton voltage multiplier circuit based on diodes D1-D5 & their associated capacitors. L:j)ER CA T~ODE _j switch, with an additional hole in front of it to accept the neon indicator. The laser tube and its companion PC board are a comfortable fit into the conduit. Before they are installed though, you will need to pack some pliant insulating material, such as corrugated cardboard, around the laser tube so that it is centrally located in the conduit. Important: be sure to install the tube the right way around. The tube specified emits light from its cathode end (ie, from the end opposite the 33kQ ballast resistor), so make sure that this end goes towards the hole in the end plate. Alternatively, you can mount the tube and PC board assembly on the lid of a plastic zippy case, as shown all current consumption of the circuit. Second, capacitor C4 (33pF) must be removed from the board and replaced with a wire link (note: this capacitor can subsequently be used on the multiplier board). Capacitor C3 can be left in circuit, even though it serves no useful purpose. Once these changes have been made, the voltage multiplier board can be assembled - see Fig.2. Begin by installing the five EHT diodes. Note that the cathode end of these diodes is indicated by a purple band on one lead (not the body) and that D2-D5 have to be mounted end on in order to fit. Note also that if you try to check these diodes using a multimeter, you will not get a result. That's because the forward voltage of these diodes is quite high at about 3V. The best way to check one of these diodes is to wire it in series with a 9V battery and a 4. 7kQ limiting resistor and then measure the voltage across it. Don't substitute for the diodes since they are a special high-voltage type which is rated at 12kV. The five disc ceramic capacitors are also high voltage types rated at 3kV and can be installed at this stage. Finally, install the 82kQ ballast resistor, then mount the inverter board on top of the rectifier board by installing three "pinthrough" connections. shown in Fig.2. Note that one end of the 33kQ ballast resistor is soldered directly to one of the tube clips. If you wish to make a laser pointer, the circuitry can be installed inside a 300mm length of 40mm OD electrical conduit. This is fitted at either end with 10mm-thick Perspex end plates. One of these, at the laser end, has a 10mm-diameter hole drilled through it to allow the laser light to escape. The other end plate carries a DC input socket, to match the one on the battery pack (note: Fig.2 shows banana style input sockets, as used in the zippy case version). A hole also needs to be drilled in the conduit at this end for a pushbutton on/off Final assembly Fig.2: before installing any parts, remove capacitor C4 from the inverter (AC drive) board & substitute a wire link. Note that the completed multiplier board assembly should be potted in neutral cure silicone sealant to reduce the possibility if arcing & accidental electric shock. Fig.3 at right is the full-size artwork for the multiplier PC board. The wiring between the board assembly, the tube and the other items of hardware can now be completed as MAY 1993 71 in the photos. To mount the tube, you'll need two cable tie mounts with adhesive bases. Attach these bases to the lid in the appropriate positions, then loop two plastic cable ties through these bases and around the tube. Pull the cable ties up firmly but don't make them too tight or you could fracture the tube. The board assembly can be attached to the lid using a suitable epoxy adhesive. After that, it's simply a matter of wiring up the on/off switch, neon indicator and power supply sockets. A rocker-style on/off switch can be used for this version. Power for the laser can be derived from a 7.2V nicad battery pack (or six 1.2V cells in series), or you can run it from a mains supply capable of supplying 7.2V at 1A. Initial testing Check your work carefully and make sure that the unit is fully enclosed in its case before applying power. The unit should fire up immediately when the battery is connected. If not, disconnect it and individually discharge each high-voltage capacitor using a well-insulated clip lead. Remember, they can give you a substan- tial shock, even ifno power is applied to the circuit. Once the capacitors have been discharged, you can safely check your work and rectify any mistakes. This done, it's a good idea to pot the highvoltage capacitors and diodes in neutral cure silicone sealant. This will help prevent arc over and also provides a further degree of protection against accidental contact with highvoltage components. Finally, be sure to attach a warning label to the unit, advising of the dangers of direct eye exposure (see warning panel). Suitable warning labels are available from the supplier listed at the bottom of the parts list. SC PARTS LIST 1 PC board, code 11104931, 66 x25mm 1 DC-DC inverter module 1 0.5mW laser tube 1 on/off switch to suit - see text) 1 300mm length of 40mm OD electrical conduit (optional see text) 2 10mm thick Perspex end plates (optional) 1 DC socket (optional) 1 plastic zippy case, 130 x 68 x 41mm (optional) 2 banana sockets (1 red, 1 black .,.. optional) 4 rubber feet for zippy box (optional) 6 AA size nicad cells 5 BY509 high-voltage diodes The laser tube is secured to the lid of the case using two cable ties & two plastic mounts with adhesive bases. Note that this tube emits from the cathode end (ie, the end opposite the ballast resistors). Capacitors 2 .01 µF 3kV ceramic 2 680pF 3kV ceramic 1 33pF 3kV ceramic Resistors (0.25W, 5%) 1 1MQ 1 33kQ 2W 1 82kQ 2W 1 1kQ Miscellaneous Hook-up wire, plastic cable ties & cable tie mounts (see text), neutral cure silicone ·sealant. Where to buy the parts Parts for this project are available from Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4985. The laser tube sells for $35, while the inverter module, multiplier PC board & high voltage components are $15 (includes warning label). Please add $5 for p&p. 72 SILICON CHIP A laser pointer can be made by sliding the tube & the PC board assembly into a length of 40mm OD electrical conduit. Pack some pliant insulating material, such as corrugated cardboard, around the laser tube so that it will be centrally located in the conduit. Be sure to fit a warning label to the case (see text). I PRODUCT SHOWCASE! Hard copy output of stored waveforms is enabled by the PM 3331 's RS232 serial port, which can be connected to either a plotter or a dot matrix printer. This facility allows displayed waveforms, including cursors, measurement readouts and other on-screen information, to be printed out for reference or visual comparison, as well as for archiving or publication. For further information, contact Philips Test & Measurement, 34 Waterloo Rd, NorthRyde, NSW 2113. Phone (02) 888 8222. New analog/digital scope from Philips The new PM 3 3 31 Combiscope®has a 40MHz analog bandwidth and a 20 megasample/second sampling rate. The sampling rate is specified for operation on both channels simultaneously and a large acquisition memory of 8Kb. This ensures excellent resolution of the captured signals, allowing detailed analysis of complex waveforms. An additional 8Kb register allows the waveforms to be stored for reference and comparisons. The PM 3331 has microprocessor controlled features such as AUTOSET which sets sensitivity, timebase and triggering on both channels, in both ANALOG and DIGITAL STORAGE modes. In addition, the DIGITAL STORAGE mode allows cursor measurements on captured waveforms, with on-screen numeric readout of the values between the cursors, making it easy to get precise values of amplitudes, frequencies and time intervals. Digitiser tablets for PCs Genius Australia has released a new range of high resolution digitiser tablets for DOS and Windows-based PCs. The HiSketch 906 is a 220x 150mm digitiser with .0lmm accuracy. It includes a 3-button smart stylus for freehand rendering in desktop publishing and has a retail price of $344.00. The HiSketch 1212 has a 300 x 300mm drafting surface and incorporates a 3-condition LED display, a slim stylus and precision puck. It retails for $756.00. TV test tuner for servicemen This test tuner will be a boon for servicemen handling front-end problems when servicing TV sets. It will enable much easier diagnosis of problems like tuner drift, low gail)., incorrect AGC and so on. It continuously covers the VHF and UHF range of Australian sets and has its own mains power supply which will simplify connection to the set under test. Also provided is an adjustable external AGC voltage which can help in diagnosingAGC problems in the IF stage of the set. Front panel controls are a power switch, 3-position bandswitch, AGC output control and the channel tuning knob which has three scales calibrated in megahertz. The tuning range is from 40MHz to 1400MHz. On the lefthand side is a Belling Lee socket for 75.Q coax connection, while an RCA socket on the righthand side provides the IF output. Recommended retail price of the Test Tuner is $250 including sales tax, plus $10 for postage and packing. At this price, it must be rated as a bargain. For further information, contact John Connerly at J. V. Tuners, 216 Canterbury Rd, Revesby, MAY 1993 73 Recommended retail price including tax is $469, while the optional sheet feeder is only $139. For further information contact Panasonic Australia, 1 Garigal Rd, Belrose, NSW 2085. Phone (02) 488 7122. New hifi range from Quad Amber Technology has been appointed exclusive Australian distributor for the . Quad range of audio products. Quad's hifi products include preamplifiers, a compact disc player, power amplifiers, FM tuners and, of course, their famous electrostatic loudspeakers. The Quad 66 preamplifier and CD player are very compact and easy to use. The two units are operated from a separate IR remote panel which has large controls and simple function labelling. The preamplifier controls volume, tilt, bass step, balance, filters, input selection and stand-by. A total of seven inputs is provided, allowing the connection of virtually any program source. The HiSketch 1812 450 x 300mm digitiser is intended for use by engineers and artists. The large workspace allows users plenty of room to design and modify graphics with pinpoint accuracy. Genius' proximity sensing function also enables precise tracing from 25mm above the tablet's surface. The model includes a slim stylus, precision puck and an LCD panel which displays cursor coordinates. Its retail price is $1050.00. The Genius HiSketch range emulates mice from Microsoft and Mouse Systems and all come complete with a stylus pen, keyboard adaptor, AutoSketch 2.0 and Microsoft Pen for Windows, as well as Windows and ADI drivers. The top two mod~ls also include a precision puck for more intensive applications. For further information, contact Genius Australia, 4 Briar St, Fulham Gardens , SA 5024. Phone (08) 356 7337 or fax (08) 235 1756. Panasonic's new dot matrix printer This new 24-pin dot matrix printer from Panasonic offers ease of use with a new setup program on disc which allows the user to change all printer 74 SILICON CHIP Nilsen takes over Elmeasco Instruments The Quad 306 and 606 power amplifiers use an identical circuit design, the only difference being power output. According to Amber, the Quad 306 provides superb performance with sufficient power to meet the requirements of most domestic systems, while the Quad 606 provides enough power for the most demanding systems. Quad hifi products are available from selected audio retailers. For further information, contact John Fitzpatrick, Amber Technology, Unit B, 5 Skyline Pl, Frenchs Forest, 2086. Phone (02) 975 1211. Nilsen Instruments has signed an agreement to take over the business of Elmeasco Instruments Pty Ltd. Nilsen Instruments is one of Australia's largest test and measurement companies, with offices in Adelaide, Brisbane, Melbourne, Perth and Sydney. Nilsen Instruments has always been strong in test and measurement and more recently, with the acquisition of Parameters, in the data acquisition and ATE fields. All the product lines currently handled by Elmeasco will be transferred to Nilsen Instruments, together with the sales and support staff. For further information, contact Nilsen Instruments Pty Ltd, 150 Oxford St, Collingwood, Vic 3066. Phone (03) 419 9999. New battery eliminators from Avico settings via the computer screen. Paper handling is also made easy with a flat pin belt, push tractor feed for continuous forms (original plus up to three copies), A4 landscape printing, auto paper load, paper park, tear-off and optional sheet feeder. The parallel port has been moved to the front left side to leave a clear path for the paper feed area, away from the printer cable. This also makes cable connection quick and easy. The KX-P1121 offers six built-in fonts with a maximum printing speed of 240cps (characters per second) in draft mode and 64cps in letter quality mode. The standard memory of 14Kb is expandible to 46Kb to reduce the time the computer is tied up when a print job is running. A new company has commenced operations to service the burgeoning market for audio, video and computer accessories. Founded by long-time industry stalwart Tom van der Meyden and backed with key staff experienced in this field, the new company is named Avico Electronics Pty Ltd. The name "Avico" is a contraction of the terms Audio, Video and Computer. Avico already has a wholesale catalog with over 400 items in stock. Their first product release is a range ofnew battery eliminators (plugpacks) especially designed to meet Australian safety standards and yes, they are fully approved. Apart from the functional styling which makes them easy to hold and plug.in, the new battery eliminators have a number of features not found on competing designs. First, they have a LED power indicator which shows that they are on. This is an excellent idea - how many times have you left a plugpack on for days at a time? Second, the 6-way voltage selector, which provides preset voltages of 3, 4.5, 6, 7.5, 9 and 12V, is on the plug New instrument cases from Rod Irving side so that once it is set and plugged in, there is no chance of little fingers fiddling with the switch and possibly damaging equipment. The eliminators are also designed to sit upside down when plugged in. This means that they can be used in floor-mounted sockets which would otherwise prevent their use. Finally, the eliminators come with a full selection of DC adaptor plugs which will suit Japanese audio equipment such as personal radios and portable CD players. All told, there are seven units in the range, with ratings of 300mA and 500mA, in both regulated and unregulated forms. The range includes fixed voltage (12V) 300mA and 500mA units, and a 12VAC model. Prices range from $14. 95 for the AC model to $19.95 for the 12V models, and from $22.95 to $39.95 for the variable models , depending on their current rating and whether they are regulated or not. For further information, contact Avico Electronics Pty Ltd, 4/163 Prospect Hwy, Seven Hills, NSW 2147. Phone (02) 624 7977 or fax (02) 624 7143. Training videotape for electronics UCANDO computer animated training videos for electronics and computer students are now available. The company now has a complete series of 12 videos, each of which ·run for about one hour. By the time the student has completed these 12 videos, he or she will have a good basic know ledge of electronics and computer hardware theory. UCANDO videos are produced in the USA ·and converted to PAL format These new plastic instrument cases will fill a need where something a little more presentable than the standard plastic Jiffy or Zippy case is wanted. They come in two halves and with captured front and rear panels. Inside, they have three slots for vertical mounting of PC boards and small integral pillars in the top and base so that boards can be mounted horizontally as well. A good quality feature is the use of brass thread inserts in the four pillars for the screws which hold the cases together. All told, there are 12 cases available and their prices range from $4.95 for the smallest case, which measures 90 x 15 x 16mm, to $16.95 for the largest, which measures 190 x 100 x 80mm. Also available is a range of six waterproof cases with clear polycarbonate lids with 0-ring seals. They range in price from $8.95 to $24.95. For further information, see the full range of cases at your nearest Rod Irving Electronics store. by UCANDO VCR Educa tional Products Co, PO Box 4603, Christchurch , 8015, New Zealand. Their phone number is (643) 3 795 5570 PC-based EPROM programmer Intended as an inexpensive alternative to a standalone programmer, the PCb as e d Model 1880 from Minato Electronics Inc converts a standard PC/XT / AT or compatible into a smart EPROM programmer. It consists of a universal programmer unit, PC adapter card, system interface cable and system diskette, and it requires a host IBM PC/ XT/ AT or compatible with at least 512Kb of RAM. 1200 device types, including PROMs, E/EEPROMs, PALs, GALs , FPLAs, FPLSs, PEELs, FPLDs, MACHs and microcontrollers can be programmed via a 40-pin standard ZIP socket. Device selection by type and manufacturer is all done from the menu. There is also a full screen editor for fuse map and memory buffer editing. A JEDEC standard vector test is provided and all 40-pin drivers are self-tested with a diagnostic program. For furth er information, contact Anitech, 52/2 Railway Parade, Lidcombe, NSW 2141. Phone (02) 749 1244. SC MAY 1993 75 A-ONE A-ONE A-ONE A-ONE A-ONE ~ ~ ~ ~ +I· 0•50V 6A REGULATED PSU ,..~ , Output voltage: ~ Z 0 < S0010 $159.95 +- 0-50V DC (+- 0-35V 5A RMS Regulated) Current: 2A, +2A=4A, +2+2=6A Overload Indicator: Current Limit Sharp cut out Output reset turn the selector to current limit point. I/P Transformer: Recommended: +/·0-35V 2.5A DUAK REGULATED PSU S0007..$4&it0"" + 0-35V/0-70V $38.40 Output voltage: OA HEAVY-DUTY REGULATED PSU SOOO&.,S149:111J' $119.20 Output voltage: 0-32V Current: Overload Indicator: Protection method: 1/P Transformer: Recommended: Current: 20A MAX Overload Protection Ranges: CUSC Overload Induced Sharp Cutting Method (SC). Overload Induced Current Limiting Method (CL). Limiting Range: (Basic) 5A+5A+5A+5A Total 20A 18V-24Vx2/30A 24+24V/800VA 2.5A LED Current Limited 18-24Vx2/6-8A 22+22V/225VA • ~ ~ < ~ 0·20V 20A REGULATED PSU S0005 $134.00 6.5V TO 18V DC REGULATED PSU S0011 $149.00 0-20V Output voltage: 20AMax Current: Overload Protection Ranges: (CUSC) (Basic) 5A+5A+5A+5A Total 20A Switch Setting. 12V-18Vx2/30A I/P Transformer: 18+18V/500VA Recommended: Output voltage: 6.5V to 18V DC (25V Max) Fully adjustable Output Current: 20A Max Current limit control:4 Steps (5A,10A,15A,20A) Ripple and noise: 15 mV Line Regulation: 0.08% + 20mV Load Regulation : 0.08% + 20mV Input Power: 18 to 20V AC 50-60HZ, 20-30A Recommended 18+18/500VA Transformer: (T0238-Parallel Secondary) 100W CLASS 'N MAIN AMPLIFIER (MONO) S0313 $79.00 120W MOSFET POWER AMP (MONO) S0329 $195.00 100W DYNAMIC CLASS 'A' MAIN POWER AMP (MONO) S0310 $89.00 Power Output: Frequency Response: Input Impedance: Input Sensitivity: Supply Voltage: Current: Power Bandwidth : THD 1KHz 1W: Transformer: Recommended Transformer: Power Output: Frequency Response: Power Output: < 0-50V 3A PRECISION PSU Output voltage: Current: Overload Indicator: Protection method: 1/P Transformer: Recommended: S0001 $49.00 0-50V 0.5 to 3A LED Auto shut on overload . and short circuit 22V-36Vx2/3A 50Vx2/3A for High O/P 36+36V/160VA 45+45V/160VA High O/P ~ ~ I < Z .< ~::;,~;:,~: ·' 0 100W8 OHM 0-100KHz 22K. 0.8V DC+/-30 -42V(MAX) 5A 5-50KHz 0.001% 28Vx2/5A 30+30V/160VA. (T0209) MONO 30+30V/300VA. (T0217) STEREO 120W RMS into 8 OHMS 8Hz to 20KHz, +0 to 0.4db Input Sensitivity: 1V RMS for 120W Output Power Requirement:+/- 45 to 55 VDC at 3A Mono 40Vx2/3A/160VA for MONO 40Vx2/6A/300VA for STERO Recommended Transformer: 40+40V/160VA. (T0212) MONO 40+40V/300VA. (T0219) STEREO Frequency Response: T.H.D.: TIO: Input Sensitivity: S/N Ratio: Power Supply: Power Consumption: Recommended Transformer: Recommended Transformer: 100W RMS into 8 OHM 150W RMS into 4 OHM 10Hz to 20KHz Less than 0,008% Less than 0.008% 0.75V- 1V Better than B0db +/-35VTO +/-45V DC 3.5A per channel. 30+30V/160VA (T0209) Mono 30+30V/300VA (T0217) STEREO 3NO-V 3NO-V 3NO-V 3NO-V 3NO-V A-ONE A-ONE A-ONEA-ONE A-ONE >. ~ -~ ~ DC FET SUPER CLASS 'A' PRE-AMP S0330 $145.00 FULL COMPLIMENTERY SYMMETRY FET STEREO PRE-AMP S0308 $159.00 300W HI-FI POWER AMP(MONO) S0331 $175,00 Frequency Response: Frequency Response: Power Output: T.H.D.: Input Sensitivity & Impedance: Phono: Output Level: Pre-AMP Output: Recording Output: Input Power: Recommended Transformer: Overall (AUX to pre output) (at rated ouput) 10 to 100,000HZ +0.5-1 db Overall (From AUX) Less than 0.01% (1,000HZ for rated output) 47K OHMS.2mV Rated Output (0.01% THD) 1.3V (20V MAX. 0.1% THD) 130mV 36+36V/0.2A 30+30V/15VA. {T0231) 10 to 100KHz +0.5db -1db T.H.D. (From AUX): 0.005% at/below rated O/P Channel Separation (at rated O/P 1 KHz) Better than ?0db. Phono: HUM & Noise (IHF) Better than ?0db. Phono: Better than 90db. AUX: Input Sensitivity & IMP. (1 KHz for rated Phono 47K OHM ,2mV output): Rated O/P(0.01 % THD). Output Level: Pre-AMP output 1.5V Max Output: (0.1 % THD) Pre-AMP output 15V. AC 30V x 2 400mA Input Power Vol: Power 12W Consumption: Recommended 30+30V/ 15VA (T0231) Transformer: Frequency Response: T.H.D. : I.M. Distortion: Input Sensitivity: Power Requirement: Recommended Transformer: 300W RMS into 8OHMS 500W Music Power into 8OHMS 10Hz to 20KHz Less than 0.05% Less than 0.05% 1V RMS at 47K +I- 60 to 75 VDC at 8A Mono 48-53x2/6-8AMP AC ~ ~ >. i 50+50V/500VA. (T0225) MONO ------------A-ONE 240V TO 110V STEP DOWN TRANSFORMERS Many people come back from an overseas trip with audio, video or computer equipment which will only run at 11 0V. They get caught. But all is not lost and some of this equipment will run.quite happily via a 11 0V isolation transformer. Pictured is one of a range of 11 0V isolation transformers manufactured by Harbuch Electronics. All are based on the company's toroidal transformers and thus they are compact and have a low residual hum field. Units are available with ratings of 60VA, 120VA, 300VA, 500VA and 625VA. The units up to 300VA are all housed in the same size case, measuring 125 x 75 x 185mm. Cat. No. Rating Price T0306 · 60VA $125.50 T0305 120VA $128.50 T0304 160VA . $138.50 T0301 300VA $149.50 T0303 500VA $183.50 T0302 625VA $199.50 Call for prices of other ratings. ELECTRONICS PTY LTD 432-434 Kent Street, Sydney NSW 2000. Phone: (02) 267 4819. Fax: (02) 267 4821. A.C N. 003 882 S13. MAIL ORDERS WELCOME: CHEQUE, MONEY ORDER, AMERICAN EXPRESS, BANKCARD,MASTERCARD AND VISA. POSTAL CHARGE $5-25 ..... ..... $4.50 $26-$50 ..... .$5.50 $51-$100 ........ $7.00 Over $100 ...... $10.00 Phone or write to us for a copy of your price list. Shop hours Mon-Fri 9-6. Sat 9-4. All prices include sales tax. >. ~ ~ :INO-V :INO-V ·:1No-v :INO-V :INO-v COMPUTER BITS BY JOE ELKHORNE Upgrading to a 386 - more on kludging a computer Last month, I had lots of fun getting the hardware of my cobbled up computer to work. But there was more fascinating frustration to come when I realised how beautifully simple it is to purchase a completely new computer. The hardware is only half of a platform, of course. Having achieved a working computer, I now had to pursue state-of-the-art software. Fortunately, I'd picked up Windows 3.1 at PC92 at a significant cost reduction $95 is a lot better than the $225 I'd the 3.0 version to get the CGA driver and then install my 3.1 "over the top". That evening, we did exactly that and both discovered how clunky Windows looks on a CGA monitor. Well, it couldn't be helped. The whole exercise was a process "A quick skim gave me enough information to be dangerous & I started the installation. To my dismay, the first problem I encountered was that a CGA driver is no longer provided." seen at a discount house when I began this exercise! I also would have bought MS-DOS 5 but they'd sold out. The dealer, however, promised to let me have one from the next shipment at the show price. Good show! I opened the white box containing the 3.1 goodies and had a quick look at the "Getting Started" booklet. A quick skim gave me enough information to be dangerous and I started the installation. To my dismay, the first problem I encountered was that a CGA driver is no longer provided. Blast! It was pointless to proceed further and I telephoned my friend Graeme. His suggestion was that we "install" 78 SILICO N CHIP of getting a machine up and running as cheaply as possible. This included using the existing inadequate 40Mb hardcard and the Amstrad CGA monitor. Incidentally, somewhere along the line, an expert told me that said monitor would never work "since they're non-standard". Having h eard the "Amstrad's aren't compatible" canard before, I took that with a grain of salt. Empirical tests proved that the monitor did function in a normal fashion attached to an ordinary CGA card. One of the curiosities I glossed over earlier was the hardcard installation itself and how we simply ignored the CMOS Setup. Well, since the compu- ter was working, we continued to ignore the anomaly. Having dropped it into a slot and found that it worked, regardless of the CMOS Setup report, there were more important matters to attend to. Since normal disc operations (including defragging) worked, the system obviously was happy to recognise it. Despite the limitations of the CGA monitor, we completed the Windows 3 .1 installation. There were some frustrations - the system "fell over" several times, although I am certain that this was due to my kludged hardware rather than the software. In the course of subsequent daily operations , the system has clagged a number of times when using file manager or even the MS-DOS Prompt. I've learned not to attempt a file copy from the A: drive to the B: drive, though admittedly it sometimes works for short files. File size seems to be a factor in whether or not the system will hang. Marking a group of files is a recipe for disaster, usually, but those same files can often be transferred one by one. Again, these problems must be located somewhere in my hardware or in the system setup. Incidentally, this is a good place to point out that - if you have anomalous behaviour - don't make assumptions about the cause. Do not blame Windows for something that might be endemic to the system. The best test when something falls over is to stay at the DOS level and try to duplicate the behaviour. Drivers, drivers everywhere Right - at this point, we have a more or less working piece of hard- ware. We've achieved disc operations at the fundamental level, even if some of the bells and whistles don't quite work. Given the previous difficulties with the floppy drives, this is hardly surprising. The monitor is definitely marginal but is usable - just. The keyboard does what it's supposed to, except when it-doesn't. Well, what would you expect from a definitely used keyboard? An occasional missed character is no big deal and the problem can be solved by throwing a little more money at it. More on this later. Since the serial card has already been tested with the modem, I know I can continue to communicate with the outside world. Ripper. The final and perhaps most important peripheral operation is hard copy. I've been using a colour printer for several years and blithely assumed it would be supported by Windows 3.1. There's a Microsoft Windows Version 3.1 Hardware Compatibility List included with the software package. This covers compatible computers (my Kludge Special wasn't listed, of course), displays, printers, networks, pointing devices and keyboards. Perusing the list, I then discover the model I have is not included. Bummer! Lots of Brand X printers, just not .mine. Now, one of the beauties ofWindows is that you need install a printer once and the graphical environment handles the talking between applications and hard copy hardware. This is, however, contingent on having the right printer driver! We did try several likely possibilities, including a couple of Epson bogstandard types, without success. Well, the X-42 (name changed to protect the guilty) is a bit long in the tooth but it is an 18-pin printer and has pr,oduced some reasonable hard copy from packages like Digital Research's GEM. I thought it would simply be a matter of getting the right driver; either Microsoft or the printer vendor was a possibility, I thought. Accordingly, I called my local Brand X dealer the next working day. They heard of anyone else trying this. Let me just check the master list on the computer". There was a long pause. It must be a big list! As the silence became uncomfortable, the technical support person (or whatever he was) said, "I'm just unzipping the file now." Then he added, idly, "Of course; three point one only supports 24-pin printers, you know. He then confirmed that the X42 wasn't on the list and suggested that what I really needed was a new "The monitor is marginal but is usable - just. The keyboard does what it's supposed to, except when it doesn't. Well, what would you expect from a definitely used keyboard?" referred me to the Sydney office, giving me a 008 number. I tried that. The telephonist understood my initial query easily. She put me straight through to the customer support officer. I explained the situation to him. "Uh, Windows?" he mumbled. "Yes." "Three point one?" "Yes." "What model printer again?" "X-42." "One of ours?" Well, I didn't get very far there. Next, I decided to call the Microsoft office in Sydney. A voice answered and I quickly explained the situation. "Umm, tricky. I don't think I've printer. Well, I hadn't argued the point but I knew after looking at the compatibility list that there were a number of 9-pin printers. Maybe his curious statement actually referred to Brand X printers and not all printers. Who knows? Who cares? By now, I was thoroughly frustrated. Just at that point in time , I got a call from the software dealer. I raced down to pick up DOS 5.0 and pessimistically took my compatibility list with me. The sales rep was not surprised at my tale of woe. I_ said I was about desperate enough to buy a new printer. He thought that a bad move, since I was essentially satisfied with my existing hardware, if I could get it to 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. * High quality with heavy board covers * Each binder _holds up to 14 issues * 80mm internal width * logo printed in gold-coloured lettering on spine & cover SILICON CHIP Price: $A11.95 plus $3 p&p each (NZ $6 p&p). Just fill in &mail the order form in this issue; or fax (02) 979 6503; or ring (02) 979 5644 &quote your credit card number. MAY 1993 79 COMPUTER BITS - Upgrading to a 386 work. He offered further suggestions to trace a source for an appropriate printer driver. I was impressed with this since it really meant no money for them. Naught came of this, however, and in the end, I-went back to the dealer and bought an inexpensive Epson. Will it work? The rep said he used one himself. I looked askance , knowing the bane of compatibility problems and pointed out that this particular model was not on the Microsoft list. "Use such-andsuch," he said. "It works". Oh, before I continue, of course I was still able to get hard copy at the DOS level. And even under Windows 3.1, the "generic" driver functioned properly. It only meant the little advantages like TrueType fonts and other graphical bells & whistles weren't available. "Ifl have any trouble, I'll be coming back with fire in my eye," I warned. The plastic money got bent a bit further that arvo and I raced home. Installing the driver under the Win- out of the ordinary there. Without even going into Windows, I did a straight DO£ copy of an ASCII file to the printer. It had errors. Not dramatic ones, to be sure. It took me a second to recognise what was wrong: no upper case characters. Just to double check, I did a hex dump and repeated the same process on the old Brand X printer. The conclusion was inescapable: a stuck bit in the interface electronics. Bah humbug, so much for the self-test earlier. At least I'd been able to eliminate the guesswork by a systematic approach. I returned to the dealer with fire in my eye. When I walked through the doorway, several people dived for cover. The wimps sent one of the young women out to see me. I told her that I had to see the sales rep and they managed to drag him out of the back room. I showed him the printouts with that inescapable evidence of hardware malfunction, I received a swap printer straight away. Back home once again, I went through the entire process from the "I returned to the dealer with fire in my eye. When I walked through the doorway, several people dived for cover. The wimps sent one of the young women out to see me." dows operating system was not difficult. Foolishly, I didn't start at Square One. Yes, I know better. Why should I take my own advice? Instead, I went to a Windows application, called up a file I'd been working on and pointed it at the printer. WYSIWYG? No way. By now, I could recognise bit streams being interpreted wrongly. Was it the driver? Even the Epson book verified what the sales rep had said. Curses, foiled again! I turned off the rig in disgust and watched Star Trek and went to bed. The following morning, I did a systematic diagnosis. I verified the selftest of the new printer. It was good. I checked the software configuration of the printer itself, just in case. Nothing 80 SILICON CHIP ground up. And of course, there was no problem at all. By the time I got into Windows and produced my first state-of-the-art hard copy, I felt like I'd been through a war. Yet another upgrade Just at this point in time, "me good ol' mate" decided he really needed a high-resolution non-interlaced monitor. With appropriate video driver card, of course. So I inherited one SVGA monitor with Tseng Labs card. It's a world of difference to see what you're doing, rather than interpolating it from a CGA monitor whose dotpitch approximates S2 glasspaper. Over the next month, I soared up the learning curve of MS-DOS 5.0, and the intricacies of Windows 3.1 and various applications. It was inevitable that missing keystrokes would frustrate me to the point of buying a new keyboard. I smirked to myself that nothing could go wrong in this regard. Sure. After all, there 's only really a very few possibilities: the original XT-style (not mine) or the original AT style (nor again), the less common 3270 type (definitely not mine), or the 101key or PS/2 or enhanced keyboard. You definitely can't interchange XT and AT types. Yes, your typical clone keyboard usually has a switch with XT I AT positions. My existing keyboard did have a switch, did have 101 keys and surely any typical enhanced keyboard would work. I discovered there was a monthly computer swap meet on and attended the venue. Several dealers had attractive keyboards at even more attractive prices. One word of advice, here: do give a prospect a bit of a run to see if you like the feel and sound! There are wide variations. I selected one and took it home. Nothing can go wrong, I said ... off with the old, on with the new. I fired up the machine and knowing the CMOS did have the keyboard test installed, waited through the 35-second boot-up procedure. No error report, good! I typed "WIN" and waited whilst the operating system loaded. When I first started to do something, the system locked up. Hey, what's this? I'd decided some time back to coin a new acronym: "I had to CAD out of Windows (again)". CAD?-Control-Alt-Delete, of course. Well, to my surprise, I couldn't even CAD. A poke on the Reset button solved that problem. I watched again through boot-up. Then I stayed at the DOS level. Tapping the keys got response. But when I hit either the Caps Lock or, on a subsequent test, the Scroll Lock, the appropriate LED came on permanently and the keyboard was locked up. Very, very strange. The leaflet in the clone keyboard box referred to "the switch" and showed one of two possibilities, depending on whether it was "a type A or type B" keyboard. The unit itself, however, had no such switch; I'd already checked and assumed it was a standard enhanced unit. I called the dealer. He'd never had a keyboard fault, naturally, but offered to swap it. I drove a considerable distance to his location and watched in dismay as he plugged "my" keyboard into an ordinary 386 clone and it worked perfectly. Since I was already there, he gave me another keyboard as a swap. Back home, it exhibited the same symptoms! At this point, I drove out to see my favourite BBS sysop (hi Sandy !) and she put this u-beaut new keyboard on one of her many computers. It worked just fine. I took a slightly used one from her in exchange - it did have a switch, set on the AT mode, of course. And it works just fine on my system. Why is 't his all so? I have no idea. All I can say is that it points up the necessity for mix and match testing. There's nothing like substitution to sort out these little problems. Swapping one part and repeating a test is the quickest and easiest answer. Conclusions What's the bottom line? It's been an interesting time to be sure , with lots of unanswered questions. At the end of it, I have a reasonably inexpensive and mostly working platform. Did I save any money? If time is money, then the answer is unequivocally "NO! " Using 20-20 hindsight to confirm things I generally knew anyway from past experience, here's a little list: (1). Change one thing at a time. (2). When in doubt, substitute. (3). Cheap add-ons without documentation may be no bargain. (4). Be systematic and thorough. (5). Don't blame one thing when another may be at fault. (6). RTFM - when all else fails, Read The Flamin' Manual. The last is particularly important when confronted with little, niggling annoyances like too-easily accessible mains select switches on power supplies. Probably more units have blown up from inadvertently flicked switches than all the component failures or supply spikes put together! And finally, keep smiling! Editor's note: readers would do well to regard this and last month's story as a cautionary tale. Upgrading hardware in this piecemeal way can be frustrating, even to the most well-informed computer user. If you want a new computer and can afford the price, sell your old one, buy the new one and sleep well at night. SC Intel Announces The Pentium Intel Corporation has announced the production version of the Pei;itium® processor. Up to five times as powerful as the 33MHz 486 DX CPU, the fifth-generation Pentium processor extends performance while maintaining full compatibility with existing software. The new processor will benefit areas such as scientific modelling, computer-aided design and engineering (CAD/CAE), large-scale financial analysis, and high-throughput client/server applications. The Pentium processor also will provide the increased performance necessary for applications such as voice recognition , imaging and real-time video. The Pentium processor will be offered in 66MHz and 60MHz versions. The speed difference between the 66MHz and 60MHz versions is about 10%. Manufactured using a 0:8µm BiCMOS process and designed using a superscalar RISC architecture, the Pentium processor has two 5-stage execution units and can process up to two instructions in a single clock cycle . Both the Intel 486 and Intel 386 have one execution unit. The Intel 386 is a traditional CISC design that utilises several clock cycles per instruction. By contrast, the Intel 486 CPU, designed with a RISC integer core , executes most instructions in a single clock cycle. The Pentium processor features two 8Kb on-chip caches, dramatically improved floating point performance, and a 64-bit burst-mode external bus. It has 3.1 million transistors - nearly three times as many as the 486 . The powerful, fully compatible floating point unit (FPU) incorporates optimised algorithms and dedicated multiply, divide and add hardware, with an 8-stage pipeline to execute one floating point operation per clock cycle. The FPU is capable of running many applications 5-10 times faster than the same applications running on a 33MHz 486DX. Other design techniques, such as branch prediction, 256-bit internal data buses and write-back caches, all serve to improve performance. Not only will current software run on Pentium processors without modification and with substantial performance improvement, but new high-performance tools and compilers are available that will allow commercial and in-house developers to achieve even greater performance enhancements through a recompilation process, also known as optimisation. Many major software developers have committed to optimising their current applications for the Intel architecture, while others are porting their high-end applications to the Intel architecture for the first time . Peripherals Intel is providing system building blocks to enable a variety of Pentium processor-based systems designed for high-performance desktop and server applications. These blocks include the 82496 advanced cache controller and 82491 cache, the 82489 DX interrupt controller, and the 82430 PCI set chip set. The Pentium processor and second-level cache chip set, the 82496 cache control ler and multiple 82491 custom SRAMs, are a tightly combined group of components optimised for high-performance desktop systems and two to eightprocessor high performance servers. The 82489 DX, the first implementation of the advanced programmable interrupt controller (APIC) architecture, provides multiprocessor system support. The Intel 82430 PCI set provides PCI local bus performance to Pentium processor-based desktop systems. It includes an integrated cache/DRAM controller, a local bus accelerator, and system logic with an EISA or ISA expansion bus bridge to enable a range of price/performance systems. Intel has begun production of the new processor and expects to ship approximately 10,000 units in the second quarter of 1993. MAY 1 993 81 AMATEUR RADIO BY GARRY CRATT, VK2YBX Kenwood's mighty little TH-28A & TH-78A transceivers The old saying that "bigger is better" is no longer necessarily correct, as we can report after checking out Kenwood's latest VHF/UHF hand-held transceiver offerings. Kenwood has released two new identically-sized hand-held transceivers: (1) the model TH-28A covering the 2-metre band, with a 70cm receive facility; and (2) the TH-78A dualband 2-metre/70cm unit. Both units offer an unbelievable range of features in such a small package. In fact, the first impression one gets of either unit is that operating it will require hours of study and a degree in Electrical Engineering. In practice, nothing could be further from the truth - they're easy to use. Designed to fit into the palm of the (Japanese) hand, both units are quite heavy, no doubt the result of the use of a diecast chassis. The units are supplied with a 7.2V 700mAh nicad battery pack which slides inside a protective cavity at the bottom of the unit. There are various power output levels available, all selectable by the Left: the TH-ZBA 2-metre FM transceiver features dual-band receiver capability (VHF/UHF) & extensive multi-scan functions. The alphanumeric display allows the user to dedicate a 6-character identifier to each of 20 memory positions. Other features include a DTMF memory function for storing up to 10 different telephone numbers plus facilities for digital message transmission. 82 SJLJCON CHIP user and dependent upon the capacity of the battery pack fitted. More on this later. The array of features is comprehensive and, in addition to the standard features expected on any basic handheld unit, includes programmable VFO tuning limits (allows the VFO to be programmed in 1MHz segments) and selectable RF output power settings of 5W, 2.5W, 2.0W, 0.5W and 20m W. These levels are dependent on the voltage and current rating of the power supply or battery used. The provision of a transmit lockout function prevents accidental transmission on a dedicated receive channel, while an in-built timer (with a maximum period of 10 minutes) prevents the "stuck microphone" problem, often the cause of blocked FM channels and particularly annoying if the frequency in question happens to be a repeater input frequency. One handy feature is the provision of a lithium microprocessor back-up battery which lasts for 20 days, even when the battery pack is removed. There are 40 user-selectable memories (50 in the TH-78A), ample for the number of dedicated FM channels in any capital city. However, the addition of the "ME-1" memory expansion unit increases this to 239 memories for those operators requiring additional capacity. Another user friendly feature is the memory channel character display, allowing the user to dedicate a 6-character alphanumeric identifier (eg, VKZRWI) to each of 20 memory positions. This is a particularly useful feature if you are travelling interstate, as the relevant repeater callsigns can be entered into memory, along with their frequencies prior to departure. This eliminates having to refer to repeater lists and amateur radio handbooks. For those wishing to scan parts of the VHF and UHF bands, both models provide nine separate scanning options, including "band scan" which instructs the receiver to scan from the lowest to the highest frequency limits and "memory scan" which instructs the receiver to scan all memory channels containing data. Unused memory channels and those deliberately locked out are skipped. The "VFO/ memory scan" function instructs the receiver to toggle between the last used memory channe.l and the VFO frequency. All scanning functions can be carrier or time interval controlled. Phone patch capability The DTMF memory feature allows telephone numbers of up to 15 digits to be stored. This is a handy feature for those involved in phone patch operations. The 3-digit dual tone squelch system (DTSS) allows squelch activation when a transmission encoded with the same 3-digit code is received. There are 999 user-selectable codes, and the duration of the code burst is extended from 250ms to 450ms to ensure reliable performance when you are using repeaters. Apart from numerals 0-9, the alphabetic characters A, B; C and D can also be used for repeater control. This feature, when used with the paging and DTSS functions, forms the basis of a digital message system. A pager facility alerts the operator to an incoming call and the DTSS feature displays the ID number of the caller. In addition, up to 10 alphanumeric messages can be kept in memory for transmission as needed, by way of reply. If the transceiver is left unattended, the last 10 digital messages (each up to six characters long) are stored in memory and can be recalled and displayed later. The "Time Alert" feature causes the transceiver to display the time the last message was received. Cross-band operation is possible with both units, although the TH-28A has no transmit facility on the 70cm band. The TH-78A allows quite extensive cross-band operations, including full duplex cross-band operation, and has the ability to receive two frequencies within the same band at the same time (either VHF + VHF or UHF + UHF). By using an external speaker, both signals can be monitored simultaneously. The TH-78A also comes equipped with the "automatic band change" function, enabling independent control of both UHF and VHF operation. Both the TH-28A and TH-78A are equipped with automatic power off and battery saver functions, to maximise battery endurance. These features, combined with user selectable RF output power settings, assist in maximising the operating hours. In addition, numerous optional accessories are available for both models. Specifically for. the TH-78A, Kenwood Australia has available the PB-17 12V 700mAh high-power battery pack, the PB-18 7.2V llO0mAh long-life battery pack, various soft cases (dependent upon the battery pack used), the BT-8 alkaline battery carrier, the PG-3H filtered cigarette lighter cord, various speaker microphones, a VOX headset (HMC-2) and a water resistant bag (WR-2). Many other options are listed and appear equally suitable for either TH78A or TH-28A. Specifications As for the technical parameters of these units, we can report that both receivers met the stated sensitivity claim of 0.18µV for 12dB SINAD and exhibited good adjacent channel rejection. Using an external 13.8V DC power supply, both transmitters drew 1.4A when operated in the high-power mode on 2-metres, while the TH-78A drew 1.5A on high power on the 70cm band. At the lowest power setting of 20mW, the TH-78A drew 120mA from the 13.8V supply. For those interested, both units use a first IF of 45.05MHz for the 2-metre receiver and 58.525MHz for the 70cm receiver. Selectivity is quoted as 60dB at 28kHz which, considering the size of the units , is adequate for UHF/VHF operations. The TH-78A has similar features to the TH-28A but is a full VHF/UHF dual-band transceiver that can receive two frequencies at the same time. A dual encoder provides independent control of the VHF & UHF bands. At the recommended price of $549 for the TH-28A and $879.00 for the TH-78A; both units offer excellent value for money. They come complete with Kenwood's 12-month warranty and are available from authorised Kenwood outlets. Acknowledgement: my thanks to Mr Yan Sabura of the Kenwood service division for his assistance in providing technical information for this article. SC MAY 1993 83 Silicon Chip BACK ISSUES July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid To Your Car; Booster For TV & FM Signals; The Discolight Light Show, Pt.1; Tone Burst Source For Amplifier Headroom Testing; What Is Negative Feedback, Pt.3. August 1988: Building A Plasma Display; Universal Power Supply Board; Remote Chime/Doorbell; High Performance AC Millivoltmeter, Pt.1; Discolight Light Show, Pt.2; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Build The Vader Voice; Motorola MC34018 Speakerphone IC Data; What Is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (Uses Rohm BA1404); High Performance FM Antenna; Matchbox Crystal Set; Electronic House Number; Converting A CB Radio To The 28MHz Band; Queensland's Powerful Electric Locomotives. November 1988: 120W PA Amplifier Module (Uses Mosfets); Poor Man's Plasma Display; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer; Screws & Screwdrivers, What You Need To Know; Diesel Electric Locomotives. December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1; Diesel Sound Generator; Car Ironies For Everyone - All About Electrolytic Capacitors. June 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3. July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor) ; Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm ; NSW 86 Class Electric Locomotives. Antenna/Demister Adaptor; SSB Adaptor For Shortwave Receivers; Why Diesel Electrics Killed Off Steam; Index to Volume 1. January 1989: Line Filter For Computers; Ultrasonic Proximity Detector For Cars; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cassette Players; Massive Diesel Electrics In The USA; Marantz LD50 Loudspeakers. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System; LED Flasher For Model Railways; Build A Simple VHF FM Monitor (uses MC3362), Pt.1; Lightning & Electronic Appliances; Using Comparators to Detect & Measure. March 1989: LED Message Board, Pt.1 ; 32-Band Graphic Equaliser, Pt.1 ; Stereo Compressor For CD Players; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Map reader For Trip Calculations; Electronics For Everyone Resistors. April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors ; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. May 1989: Electronic Pools/Lotto Selector; Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; LED Message Board, Pt.3; Elec- September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1 ; AlarmTriggered Telephone Dialler; High Or Low Fluid Level Detector; Simple DTMF Encoder; Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669). October 1989: Introducing Remote Control; FM Radio Intercom For Motorbikes Pt.1 ; GaAsFet Preamplifier For Amateur TV; 1Mb Printer Buffer; 2-Chip Portable AM Stereo Radio , Pt.2; Installing A Hard Disc In The PC. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); Sensitive FM Wireless Microphone ; FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio, Pt.3 ; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Railways. December 1989: Digital Voice Board (Records Up To Four Separate Messages); UHF Remote Switch; Balanced Input & Output Stages; Data For The LM831 Low Voltage Amplifier IC; Installing A Clock Card In Your Computer; Index to Volume 2. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Speeding Up Your PC; Phone Patch For Radio Amateurs; Active Antenna Kit; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. l r------------------------------ ---- - ---, _Use this handy form to order your back issues Please send me a back issue for: O October 1988 O November 1988 O March 1989 o April 1989 0 September 1989 0 October 1989 O February 1990 O March 1990 O July 1990 O August 1990 O December 1990 o January 1991 O May 1991 O June 1991 O October 1991 O November 1991 0 March 1992 o April 1992 O August 1992 O September 1992 O January 1993 O February 1993 0 July 1988 O December 1988 o May 1989 o November 1989 0 April 1990 o September 1990 0 February 1991 0 July 1991 O December 1991 0 May 1992 O October 1992 O March 1993 Enclosed_is my cheque/money order for $___or please debit my: 0 August 1988 January 1989 0 June 1989 O December 1989 0 May 1990 o October 1990 0 March 1991 o August 1991 O January 1992 O June 1992 O November 1992 O April 1993 o 0 Bankcard Card No. Signature _ _ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_ _ /_ _ O Visa Card 0 O 0 O o O Q 0 O 0 O September 1988 February 1989 July 1989 January 1990 June 1990 November 1990 April 1991 September 1991 February 1992 July 1992 December 1992 O Master Card $A6.00 each (includes p&p). Overseas orders add $A 1 each for postage. NZ orders are sent air mail. Street _ _ _ _ _ _ __ __ _ _ _ _ _ __ _ _ _ _ _ _ __ Detach and mail to : SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 Suburb/town _ _ _ _ __ ________ Postcode _ _ _ _ __ Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 6503. Name ____________________________ ALLOW TWO WEEKS DELI VERY L _ _ _ _ _ _ _ _ _ _ _ _ _PLEASE ___ ___ __ _ _FOR __ __ __ __ ________ 84 SILICO N CHIP _i- February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2; PC Program Calculates Great Circle Bearings. March 1990: 6/12V Charger For Sealed LeadAcid Batteries ; Delay Unit For Automatic Aritennas; Workout Timer For Aerobics Classes; 16Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. April 1990: Dual Tracki ng ±50V Power Supply; VOX With Delayed Audio; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Active CW Filter For Weak Signal Reception; How To Find Vintage Radio Receivers From The 1920s. Pt.2; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2; Playing With The Ansi.Sys File; FSK Indicator For HF Transmissions. May 1991: Build A DTMF Decoder; 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1 ; Setting Screen Colours On Your PC. June 1991: A Corner Reflector Antenna For UHF TV; 4-Channel Lighting Desk, Pt.1 ; 13.5V 25A Power Supply For Transceivers ; Active Filter For CW Reception ; Electric Vehicle Transmission Options; Tuning In To Satellite TV, Pt.1. May 1990: Build A 4-Digit Capacitance Meter; High Energy Ignition For Cars With Reluctor Distributors ; The Mozzie CW Transceiver; Waveform Generation Using A PC, Pt.3; 16-Channel Mixing Desk, Pt.4. July 1991: Battery Discharge Pacer For Electric Vehicles; Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2; PEP Monitor For Amateur Transceivers. June 1990: Multi-Sector Home Burglar Alarm ; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Supplies ; A Speed Alarm For Your Car; Design Factors For Model Aircraft; Fitting A Fax Card To A Computer. August 1991: Build A Digital Tachometer; Masthead Amplifier For TV & FM ; PC Voice Recorder; Tuning In To Satellite TV, Pt.3; Installing Windows On Your PC; Step-By-Step Vintage Radio Repairs. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-500kHz) ; Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; Low-Cost Dual Power Supply; Inside A Coal Burning Power Station; Weather Fax Frequencies. September 1991: Studio 3-55L 3-Way Loudspeaker System; Digital Altimeter For Gliders & Ultralights, Pt.1 ; Build A Fax/Modem For Your Computer; The Basics Of AID & DIA Conversion; Windows 3 Swapfiles, Program Groups & Icons. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2. October 1991: Build A Talking Voltmeter For Your PC, Pt.1 ; SteamSound Simulator Mk.II ; Magnetic Field Strength Meter; Digital Altimeter For Gliders & Ultralights, Pt.2 ; Getting To Know The Windows PIF Editor. September 1990: Music On Hold For You r Telephone; Remote Control Extender For VCRs ; Power Supply For Burglar Alarms; Low-Cost 3Digit Counter Module; Simple Shortwave Converter For The 2-Metre Band. October 1990: Low-Cost Siren For Burglar Alarms ; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; U;,ing The NE602 In Home-Brew Converter Circuits. November 1990: How To Connect Two TV Sets To One VCR ; A Really Snazzy Egg Timer; LowCost Model Train Controller ; Battery Powered Laser Pointer; 1.5V To 9V DC Converter; Introduction To Digital Electronics; Simple 6-Metre Amateur Transmitter. December 1990: DC-DC Converter For Car Amplifiers; The Big Escape - A Game Of Skill; Wiper Pulser For Rear Windows; Versatile 4-Digit Combination Lock; 5W Power Amplifier For The 6Metre Amateur Transmitter; Index To Volume 3. January 1991: Fast Charger For Nicad Batteries, Pt.1 ; The Fruit Machine; Two-Tone Alarm Module; Laser Power Supply; LCD Readout For The Capacitance Meter; How Quartz Crystals Work ; The Dangers When Servicing Microwave Ovens. February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Inverters For Fluorescent Lights ; LowCost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System . March 1991: Remote Controller For Garage Doors, Pt.1 ; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tune r, Pt.2; Multi-Purpose 1/0 Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV ; A Look At The Config.Sys & Ansi.Sys Files. April 1991: Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, November 1991: Colour TV Pattern Generator, Pt.1 ; Battery Charger For Solar Panels ; Flashing Alarm Light For Cars; Digital Altimeter For Gliders & Ultralights, Pt.3; Build A Talking Voltmeter For Your PC , Pt.2; Error Analyser For CD Players Pt.3; Modifying The Windows INI Files. December 1991: TV Transmitter For VCRs With UHF Modulators; lnfrared Light Beam Relay; SolidState Laser Pointer; Colour TV Pattern Generator, Pt.2; Windows 3 & The Dreaded Unrecoverable Application Error; Index To Volume 4. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V BA Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Automatic Controller For Car Headlights; Experiments For Your Games Card; Restoring An AWA Radjolette Receiver. February 1992: Compact Digital Voice Recorder; 50-WatVChannel Stereo Power Amplifier ; 12VDC/ 240VAC 40-Watt Inverter; Adjustable 0-45V BA Power Supply, Pt.2; Designing A Speed Controller For Electric Models. March 1992: TV Transm itter For VHF VCRs ; Studio Twin Fifty Stereo Ampl ifier, Pt. 1; Thermostatic Switch For Car Radiator Fans; Telephone Call Timer; Coping With Damaged Computer Directories; Valve Substitution In Vintage Radios ; The AR-1500 & AR-2800 Scanning Receivers . April 1992: lnfrared Remote .Control For Model Railroads; Differential Input Buffer For CROs; Studio Twin Fifty Stereo Amplifier, Pt.2 ; Understanding Computer Memory; Switching Frequencies in Model Speed Controllers; Aligning Vintage Radio Receivers, Pt.1. May 1992: Build A Telephone Intercom ; LowCost Electronic Doorbell ; Battery Eliminator For Personal Players ; lnfrared Remote Control For Model Railroads, Pt.2; A Look At Large Screen High Resolution Monitors; OS2 ls Really Here; Aligning Vintage Radio Receivers , Pt.2. June 1992: Multi-Station Headset Intercom , Pt.1; Video Switcher For Camcorders & VCRs ; lnfrared Remote Control For Model Railroads, Pt.3; 15Watt 12-240V Inverter; What's New In Oscilloscopes? ; A Look At Hard Disc Drives. July 1992: Build A Nicad Battery Discharger; 8Station Automatic Sprinkler Tinier; Portable 12V SLA Battery Charger; Off-Hook Timer For Telephones; Multi-Station Headset Intercom , Pt.2 ; Understanding The World Of CB Radio ; Electronics Workbench For Home Or Lab. August 1992: Build An Automatic SLA Battery Charger; Miniature 1.5V To 9V DC Converter; The lnterphone Digital Telephone Exchange, Pt.1 ; Dummy Load Box For Large Audio Amplifiers; Internal Combustion Engines For Model Aircraft; Troubleshooting Vintage Radio Receivers. September 1992: Multi-Sector Home Burglar Alarm ; The lnterphone Digital Telephone Exchange , Pt.2 ; General-Purpose 3½-Digit LCD Panel Meter; Track Tester For Model Railroads ; Build A Relative Field Strength Meter. October 1992: 2kW 24VDC To 240VAC Sinewave Inverter; Multi-Sector Home Burglar Alarm , Pt.2; Mini Amplifier For Personal Stereos ; Electronically Regulated Battery Charger (Charges 6V, 12V & 24V Lead-Acid Batteries) ; Internal Combustion Engines For Model Aircraft, Pt.2. November 1992: MAL-4 Microcontroller Board, Pt. 1; Simple FM Radio Receiver; lnfrared Night Viewer; Speed Controller For Electric Models , Pt. 1; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.2 ; Automatic Nicad Battery Discharger; Modifications To The Drill Speed Controller. December 1992: Diesel Sound Simulator For Model Railroads ; Easy-To-Build UHF Remote Switch ; MAL-4 Microcontroller Board, Pt.2; Speed Controller For Electric Models, Pt.2; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.3; High Voltage Probes - Beware The Dangers; Index To Volume 5. January 1993: Peerless PSKS0/2 2-Way Hifi Loudspeakers; Flea-Power AM Radio Transmitter ; High Intensity LED Flasher For Bicycles ; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.4 ; · Speed Controller For Electric Models, Pt.3 ; Restoring A 1920s Kit Radio February 1993: Three Simple Projects For Model Railroads; A Low Fuel Indicator For Your Car; Audio Level/VU Meter With LED Readout ; Build An Electronic Cockroach; MAL-4 Microcontroller Board , Pt.3 ; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.5; File Backups With LHA & PKZIP. March 1993: Build A Solar Charger For 12V Batteries; An Alarm -Triggered Security Camera; LowCost Audio Mixer for Camcorders; Test Yourself On The Reaction Trainer; A 24-Hour Sidereal Clock For Astronomers ; Sanyo's Big Screen Video Projector; Sony's VGP-G700 Colour Video Printer. April 1993: Solar-Powered Electric Fence ; Build An Audio Power Meter; Three-Function Home Weather Station; 12VDC To 70VDC Step-Up Voltage ConvMer; Digital Clock With Battery BackUp; A Look At The Digital Compact Cassette. PLEASE NOTE: all issues from November 1987 to June 1988 plus the August 1989 issue are now sold out. All other issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copies (or tearsheets) at $5.00 per article (incl. p&p). When supplying photostat articles or back copies , we automatically supply any relevant Notes & Errata at no extra charge . MAY 1993 85 The Story Of Electrical Energy, Pt.23 This month, we present the second story on the production of aluminium. We look at how alumina is separated from the bauxite ore in a chemical process which takes lots of energy, in the form of electricity, coal & natural gas. By BRYAN MAHER The Bayer process to extract alumina from bauxite ore and the HallHeroult process of electrolytic smelting of alumina to obtain the pure metal have remained the backbone of the aluminium production industry for over 100 years. However, many advances have been made in these process and the amount of energy needed has been significantly reduced. Australia is the biggest producer of alumina in the world and much of our production is shipped to smelters in other countries. Alumina and bauxite together rank fourth (after coal, wheat and wool) in Australia's annual exports. Worldwide, nearly 100 million tonnes of bauxite are refined annually by the Bayer chemical process. These are the digesters & flash tanks. The digesters dissolve the bauxite in caustic soda under conditions of high pressure & temperature. The flash tanks then produce considerable amounts of steam as the resultant slurry is reduced to atmospheric pressure in several stages. 86 SILICON CHIP And the world's largest refinery happens to be the Queensland Alumina Ltd plant at Gladstone in Central Queensland. This plant is run by the consorti um QAL (Queensland Alumina Ltd), formed in 1967. Initially, CRA joined with Kaiser Aluminium of the USA to form the Commonwealth Aluminium Corporation (later renamed Comalco) in 1956 to develop the Weipa bauxite deposits. In choosing a site for the alumina refinery, Weipa was considered first but rejected as unsuitable. The present site at Parson's Point, Gladstone was purchased in 1963, leaving room for future expansion. Alcan of Canada and Pechiney of France then joined the consortium and construction of the alumina refinery comrn'enced. The original Gladstone plant was designed to produce 360,000 tonnes of alumina a year but immediately plans were put in hand to upgrade it to 600,000 tonnes. From 1967 to 1973, three further expansions of the plant took place. The third expansion increased the production of alumina to 2,400,000 tonnes per year, a sevenfold increase on the original design. Today the plant produces 3,325,000 tonnes of alumina annually, employs a workforce of 1200 and receives eight million tonnes ofbauxite by ship from Weipa each year. To refine this ore, 630,000 tonnes of caustic soda and 140,000 tonnes of limestone are required. The alumina produced is shipped to aluminium smelters in Tomago, NSW; in Bell Bay, Tasmania; and in New Zealand, the USA and Canada. Alumina ore is also sent by conveyor belt to the giant smelter at nearby Boyne Island. The Bayer process In 1888, the Austrian chemist Karl Bayer discovered that alumina could be dissolved in a solution of sodium hydroxide (caustic soda), given sufficiently high temperature and pressure. Thus, the Bayer refinement process is essentially one of dissolving alumina in caustic soda to separate it from the other chemicals in bauxite, and then crystallising the alumina from the solution after the red mud has been settled out. A typical analysis of bauxite is 50% aluminium oxiqe, 12% ferric oxide, 5% silicon dioxide, 3% titanium oxide, 0.03% alkalis and 0.01 % chlorides, plus small quantities of gallium and rare earth metals. The alumina contained in bauxite may be either the monohydrate form Boehmite (Al 2 0 3 .H 2 0), or the trihydrate type Gibbsite (Alz0 3 .3H 2 0). The deposits at Nhulunbuy are 98% Gibbsite, while the Weipa field has separate deposits of both types, the Boehmite predominating. The refining plant at Gladstone has been designed to accept both types of ore, but separately. Grinding mills The bauxite ore is first ground in seven two-compartment combined rod/ball mills. These mills are the largest electro-mechanical units in the plant, with motors ranging from 1.ZMW to 1.6MW. Because the grinding mills run continuously, synchronous motors are preferred. These motors draw a leading power factor from the electricity mains. This is used to compensate for the lagging power factor drawn by induction motors elsewhere in the plant. Thus, the overall system power factor is improved which means better utilisation of the Gladstone power plant and the overall distribution system. A 10% solution of caustic soda in water is added in the mills to form a thick slurry which is pumped out to the pre-treatment tanks. These are heated to allow silication to take place. The silica products pass out through the system as sodium aluminium silicate waste compounds. High-temperature digesters From the pre-treatment tanks, the caustic/bauxite slurry is pumped into high temperature digesters where steam is injected to heat the mixture to above 240°C. To prevent boiling, the digester tanks are pressurised vessels , operating above 3500kPa (about These two aerial photographs show the extent of the world's largest alumina refinery at Gladstone in Queensland. It produces over three million tonnes of alumina each year. 500 psi) . Under these conditions and with agitation , the bauxite breaks up. The alumina content dissolves in the caustic solution, while the iron oxide and other niinor compounds remain as solids in suspension. After digestion, 70% of the bauxite mass is in solution in the caustic liquor, while the remaining 30% undissolved waste takes the form of a thin red mud suspension. This liquor is now flash-cooled to atmospheric boiling temperature and pressure. Considerable amounts of steam are generated as the pressure is reduced in stages down to atmosphere and this steam is used later in the process to preheat the liquor coming from the settling tanks . The final steam condensate is returned to the Gladstone power station boilers as feed water and some is used MAY 1993 87 These are the huge rotary kilns which dry the alumina slurry after crystallisation has taken place. The kilns are continuously rotated by 200kW induction motors through a multistage gearbox & are gas fired to 1100°c. for washing the red mud waste from the settling tanks. Sweetening The more soluble trihydrate type bauxite lode at Weipa is separately mined and shipped to Gladstone. Passing through its own grinding and pretreatment facility, the Gibbsite is easily digested at lower temperatures and the additional bauxite slurry is injected into the main stream in the flash tanks to maximise the alumina content in the liquor. This mixing, called sweetening, occurs at a point where the stream temperature is below 200°c. The red mud waste is extracted from the liquor stream by holding it in large h orizontal settling tanks. The clarity of the liquor is improved by adding flocculants to accelerate settling. 88 SILICON CHIP The overflow from the mud settling tanks, after further filtering, becomes the wanted clear liquor. This is now a hot super-saturated solution of alumina in caustic soda and water. It is cooled by flash evaporation, by subjecting it to a partial vacuum. This also generates lots of steam and this is recycled to heat the spent liquor stream returning to the digesters. Crystallisation of alumina The dissolved alumina in the form of sodium aluminate is recovered from the clear filtered liquor by seeded crystallisation. This occurs in a series of vertical tanks 30 metres in diameter. Sodium aluminate crystallises out to give trihydrated alumina plus caustic soda. The cooled pregnant liquor flows to rows of agitated precipitation tanks which are seeded by intro- ducing crystals of solid trihydrate alumina. The liquor is held in each tank for about three hours before passing on to the next. The whole crystallisation process takes 25-30 hours, producing crystals of various sizes along the way. The sizing of the crystals is a carefully controlled process. The liquor entry temperature into the crystallisation tanks , temperature gradient across each tank, seeding rate, caustic soda/water concentration and holding time are all vital in the control of crystal size. The crystalline alumina trihydrate is removed from the tanks by an auger feed and the crystals are separated into three size ranges in gravity classifiers. The major coarse fraction is the wanted product to be smelted later while the smaller crystals are used as seeds in the crystallisation tanks. The overflow from the classifiers is the spent caustic soda solution. This is re-concentrated by evaporating the water, heated and then recycled back to the digesters, to begin the whole process cycle again. After the gravity classifiers , the alumina trihydrate slurry is treated to remove both combined and free water. This is done by passing it through a series of calcinating units. First in the line is a circulating fluidised bed calciner and then nine rotary kilns, each four metres in diameter and 100 metres long. These huge kilns are rotated by zookW induction motors, driving through a multistage gearbox. The kilns are gas fired to 1100°c, to remove all free and combined water from the alumina. After cooling to below 90°C, the finished product - dry, sandy, white alumina - is stockpiled in enclosed storage buildings. Conveyor belts then carry the product either to the overseas shipping wharf on South Trees Island, or overland to the Boyne Island Smelter. Naturally, the whole process is subject to computer control. Electronic sensors monitor all temperatures, pressures, flow speeds, bauxite input rates, liquor concentrations and other parameters at hundreds of points in the plant, and send all data on-line to one large central computer. This optimises output and minimises energy requirements. Next month we shall look at the most energy intensive stage in the production of aluminium - the smelting of the alumina. SC Acknowledgements Special thanks for photographs and data to Queensland Alumina Ltd; Noel Wootton and Eric King ; and to C. A. Kneipp and Nabalco. r/.fl&fl~ ANTENNAS 3el 10-11m ............................ $152.00 4el 10-11m ............................ $192.00 5el 10-11m .... .... ........ .. .......... $233 .00 Duoband 10-15m ................. . $249.00 Delta Loop 10-11m .. ............ .. $172.00 5/8 Vertical 10-11m ................ $109.00 3el 15m .... .. ... ... .... .... ...... ....... $171.00 3el 20m ..... ............................ $279.00 6el 6m .. .. ............ .......... .... ..... $181 .00 5el 2m ..................................... $70.00 12el 2m .. .... .... .... ........ .. .. ...... . $112.00 2m Dingo ................................. $86.00 Multiband vertical, no traps ...... ....... ...... ...... .. ...... $245.00 25/8 C-Linear UHF Antenna .... $76.00 Tri Band Beam, No Traps Linear Resonators 10, 15, 20 metres ALL PRICES PLUS FREIGHT We are the new owners of the exclusive range of W. Wulf antennas & aim to provide the same quality service and antennas that you have come to expect, so please call us and discuss your antenna needs. Call Andy Coman, VK3WH Lot 6, Websters Road, Clarkefield 3429 (054) 28 5134 Silicon Chip Binders ; ',, · \ 'ih.; ' ' n I : .. ...,,~ . . . These beautifully-made binders wi ll 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 Box 139 Collaroy Beach 2097 As in any modern chemical plant, there are countless large tanks & hundreds of kilometres of piping. The 40-metre diameter tanks in the foreground are settling tanks, used to separate out the red mud from the caustic soda solution. Or fax (02) 979 6503; or ring (02) 979 5644 & quote your credit card number. MAY 1993 89 ASK SILICON CHIP Got a technical problem? Can't understand a piece of jargon or some technical principle? Drop us a line and we'll answer your question. Wr~te to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Camcorder audio mixer has high bandwidth I am writing regarding the Audio Mixer For Camcorders published in the March 1993 issue of SILICON CHIP. First, allow me to congratulate you on a useful project which I'm sure will prove to be very popular. It is a wonder such devices are not more common , although I suppose most people would be using a studio type mixer to incorporate 'outside' audio on their sound tracks. However, I am curious as to why the upper frequency cut-off is so high at 72kHz. Wouldn't the circuit provide superior performance if this was lowered to just above the human hearing range, or has this been done in order to keep the gain lower and thus prevent distortion? (S. M., Heidelerg, Vic). • The upper frequency cut-off of the mixer at 72kHz is more or less arbitrary. However, if you bring the cutoff frequency down too much you will inevitably reduce the flatness of the response above 15kHz while making no audible improvement in the residual noise. How to detect end of charge for nicads I am writing to obtain information about a 7.2V peak detection circuit for nicad batteries. The circuit is needed for a fast charger with the peak detector detecting when the cells have taken a full charge and then reverting over to trickle charge, to give the cells the optimum charge possible. Any information would be of great assistance. (B. C., Campbelltown, NSW). • Detecting the end-of-charge point for a nicad battery is not a simple matter since the voltage itself is not precise - it is affected by the temperature of the cells. In fact, what happens is that when the cells reach the endof-charge point, the voltage actually takes a small dip. Hence, the detection circuit needs to switch at this dip rather than at a precise voltage. We have published two circuits which you may find useful in detecting end of charge: (1) the Megafast Charger in June 1988; and (2) the Fast Nicad Charger in the January and February 1991 issues. The first circuit was fairly simple while the second circuit used a digital-to-analog converter and was more precise. On the other hand, if you just want a simple circuitto detect a 7.2Vthreshold, you will find a precise circuit in the Nicad Battery Discharger featured in the November 1992 issue of SILICON CHIP. Surround sound decoder wanted Tacho for 2-cylinder motor I would like to use the Digital Tachometer featured in the August 1991 issue of SILICON CHIP in conjunction with a 2-cylinder outboard motor. I understand that I would need to use a different value for resistor Rx to make it suitable for a 2-cylinder motor but I am not sure how to do the calculations. Can you help me? (B. A., Brookvale, NSW). • Resistor Rx sets the gating time for the counter and, as noted in the article, is varied according to the number of cylinders in the motor. However, not stated in the article was the assumption that the circuit would be used with a 4-stroke motor. For a 4-cylinder 4-stroke motor, the number of sparks per revolution is two; for a 6-cylinder motor, it is three and for a VB, it is four. 90 SILICON CHIP However, a 2-stroke motor has twice as many power strokes per revolution as a 4-stroke. Hence, a 2-cylinder 2-stroke motor has the same number of sparks per rev as a 4-cylinder 4-stroke motor. Therefore, if your motor is a 2stroke, Rx should be the same as specified for a 4-cylinder engine ie, 82kQ. If the motor is a 4-stroke, change Rx to 150kQ and follow the calibration procedure given in the article. However, there is one other factor to consider. If your outboard motor is a 2-stroke, it will probably use a magneto-driven capacitor discharge ignition, with one coil for each cylinder.. In that case, the tachometer circuit should be connected to the primary of one ignition coil and therefore you will be measuring one spark per revolution. In that case, change Rx to 150kQ and proceed as outlined above. I would be very interested if you were able to publish a Dolby® ProLogic Surround Sound Processor, preferably one that can feed the existing amplifiers that I have. As you may be aware, there is substantial promotion of the 5-speaker surround sound systems currently. Could you also advise whether the speakers that are now advertised as being suitable for placement close to television sets have been specially designed so as to avoid interference with the television picture, or whether they are conventional speakers that have been shielded in some way? I am interested in the process involved, in par\ because I have_ a number of excellent speakers which I wish to use for surround sound close to a television set and would like to be able to provide some kind of magnetic shield if this is possible. (H. P., Balwyn, Vic). • It is unlikely that we can publish an article on a Dolby®Pro-Logic Surround Sound Processor, since the Dolby® logic chips are only available to licensed manufacturers. It is not possible to magnetically shield existing loudspeakers. Speakers for use close to TV sets have their magnets shielded with an additional magnet and shroud assembly which cancels any leakage magnetism from the main magnet. The only way is to buy speakers which have been magnetically shielded during manufacture. How to combine two TV antennas I noted the question from A. S., of Denmark, WA, on how to combine signals from two antennas for channel 2 and channel 9. This is easily done by purchasing a Hills, Kingray or Telebrite high-band/low-band VHF diplexer, with AC pass on the highband input. These devices are in very common use in this area, where we have local channel 3, plus channels 7, 9 and 10 from Sydney; exactly the same situation as described. All the companies mentioned are Australian, although Taiwanese diplexers are also available. We have found the-latter to be very lossy, as well as unreliable. (P. M., Maitland, NSW) . Advice on sinewave inverter I am building the 2kW Sinewave Inverter published in the October 1992 to January 1993 issues of SILICON CHIP. Since I can't afford the kit price I have designed my own PC boards and have sourced parts separately. However, the one part I do not have yet is the sinewave table ROM. Is this ROM available separately? In case it isn't available, I have written a "C" program to generate the sine table. To do so, I have had to make several assumptions: (1) switching frequency of 4kHz, therefore 8192/40 timeslots (in lOms) = approx 205 memory locations plus 250µs (4kHz); (2) deadband time of four memory locations between D6 and D5; and (3) resolution of 180/40 = 4.5 degrees, therefore sine table in steps of 4.5 degrees . Are these assumptions correct? If not, could you please correct me or send the ROM contents. I also need the full design details of the main inverter transformer as I have pur- Shopping for old radio parts I enjoy reading the Serviceman's Log and the Vintage Radio column every month. I have collected a number of old radios and have restored them but I require a few parts to complete them and I was wondering if another reader may be able to help me. I require a dial glass , a handle and retaining screws for a HMV model 600 or 601 portable radio. I also need a control knob, a speaker lead with a 2-pin plug and a button for earth shielding for a 1951 Astor FK-6181 6V car radio. Now I may be able to help other readers. I built the 0-45V, BA power supply described in the January and February 1992 issues of SILICON CHIP. The only trouble I had was that I wired switch S2 the wrong way around. After fixing this it worked fine . But when I used it a couple of weeks ago, it chased the ferrite core and all the other parts. Congratulations on an excellent design. (B. M., Canterbury, NZ). • Your assumptions about the sinewave table in the ROM are essentially correct. There are also some subtleties which allow for the fact that saturation in the IGBTs can cause flattening of the sinewave when the duty cycle approaches 100%. However, as noted several times in the series of articles, the design copyright of this project is owned by Rod Irving Electronics. This means they also own the ROM contents. We suggest that you approach this company direct (phone 613 543 2166) to obtain a copy of the ROM. They may also be able to supply details of the transformer but it is really not a job for the do-it-yourselfer. It is a very difficult transformer to wind. Cruelty to (electronic) insects I liked the look of the Electronic Cockroach published in the March 1993 issue so I pulled a few wings and legs off it to produce a simple circuit. I used it to run my Lima test cooked the toroidal mains transformer secondary winding due to a shorted FB2502-35 bridge rectifier. I fixed the transformer by rewinding the secondary with 15 gauge B&S wire and by replacing the bridge rectifier with a new unit rated at 100 PIV and 35A. I also put a l0A fuse in one leg of the secondary winding, so this should now blow instead of cooking the transformer. Yes, it is shutting the gate after the horse has bolted. No, the fuse in the mains line did not blow; this is why I put in the new fuse. (Keith Lang, PO Box 174, Esperance, WA). • We agree that a fus e in the secondary is probably a good idea. However, we think that a value of l0A may be too low and could be inclined to blow at switch on or when the supply is delivering full current. With that in mind, a l0A "slo-blo" fuse may be a better choice. bogie and was pleased to see it run with 1.5V or less across the terminals, where previously 2.3V was a good starting voltage. It was also no longer sensitive to where the brushes happened to be at start-up. We are out of Johnson 170 motors here, so slot car motors and 24V motors from a UBix copier were tried. These were good at low speed but there is too much feedback , hence circuit B which is to be tried next. It was meant as an auxiliary Railpower controller but my Rail power is on indefinite loan/assessment. I'm feeding it from a 6/9/12V DC plugpack which I have found in the past cuts out if you use a 2200µF electro for smoothing. Therefore, poorly regulated DC is being fed to a l000µF capacitor and thence to a 12V regulator. There could be some beating between the pulse frequency and the lO0Hz ripple superimposed on the DC input. (D. W., Christchurch, NZ). • Thanks for your comment regarding your modified cockroach but if you want it as an auxiliary Rail power why not go to the source and modify the Railpower instead? It will give better speed control. A suitably abMA Y 1993 91 Casualties in a Studio Twin Fifty Can you please help? I have just completed building the Studio Twin Fifty Amplifier from Jaycar's kit. I checked the circuit visually and with a meter before applying power and could not discover any misplaced components. On power up, all test voltages were nominally OK although the voltages across the 0.47Q 3W emitter resistors varied from SmV to 1 lmV and the output offset voltage seemed a little high at about 33mV. · I also had a problem setting the quiescent current which would slowly rise, stabilise, then slowly start to rise again. However it would eventually appear to stabilise and was set at this level. I also noticed that this seemed to be temperature related, as blowing on the heatsink would cause it to fall. The amplifier was run for a couple of hours with a source and output connected and, even at high volume levels, the heatsink did not become too warm. The problem occurred when the amplifier was left idling for about two hours. The heatsink became breviated form of the circuit was published on page 15 of the August 1992 issue of SILICON CHIP. Making PC boards with a photocopier Following the breakthrough in this area by Glen Andersson in the February 1993 issue (page 25), the following method applies the same principle but using a photocopier instead of a laser printer. I start with a full size PC artwork (usually the solder side view in a magazine) and I set the photocopier for the darkest yet clear imprint on some test papers and then I make a copy on a transparent plastic sheet. The special thermal plastic sheets for photocopying are available from drawing supply/art shops at about $1.00 for an A4 sheet and these can be cut in half (150 x 200mm) to copy small PC boards. Now use the transparent copy but with the artwork facing upwards so 92 SILICON CHIP almost too hot to touch. I turned it off and let it cool down a little, then turned it on and applied a source. The fuses in each channel blew, as did Darlington transistor TIP147 (Q9) in the left channel (the right channel seems OK). I wonder if you could suggest any reason for the above fault and also nominate any other components that may have been damaged. I have tested all as far as my limited knowledge will allow and all seem OK. Is this a common fault, or have I missed a Notes and Errata on this project, or have I done something wrong in construction? (D. E. , Ceduna, SA). • From your description, it seems likely that there is a problem with the quiescent current monitoring circuitry involving Q7 in one or both channels. Is this transistor in good contact with the main heatsink and have you used heatsink compound on both sides of the mica washers of all transistors which are mounted on the heatsink? There have been few instances of problems with this kit and certainly none that could be regarded as common. that this now becomes the component view copy master. Make a copy of that master using another sheet or half sheet of the transparent plastic, or as many copies as you want PCBs. On a wire rack in a domestic convection/microwave oven, place a very flat and rigid plate of metal, glass or ceramic tile. On top of this place the copper PC blank with polished side up (steel wool and no finger prints as usual), then one of the new reverse transparent copies (carbon side down, solder view facing you), then 20 or more squares of flat newspaper to act as a pressure pad, then another thick piece of flat material, then a house brick for applying pressure. Set the oven to convection and 150°C for 50 minutes or perhaps one hour if glass or ceramic plates have been used. Leave everything intact to cool down overnight. Using this method, I have found that about 95 % of the pattern has been reproduced onto the PC board. I then touch up imperfec- tions with an etch resist pen and etch the board in the usual way. Most people can access a photocopier at a library or business, and the convection/microwave is not too uncommon nowadays, so to my way of thinking messy developing chemicals and darkroom work are now unnecessary for most hobbyists. I could be wrong but having made my first etched PC board in 20 years of dabbling in electronics, and with little fuss at that, this method must surely represent a breakthrough. (G. H. , Doubleview, WA). • While we have yet to try this method, it does seem as though it could work quite well. However, we must issue a few cautions. First, make sure that any transparency film you use is suitable for the photocopier you have access to. Generally, the film packet should have a long list of copiers on it that are suitable. Some copiers are not suitable for use with plastic transparency film , as it can damage the drum. If that happens, the repair bill could run to $700 or more so be warned. Second, don't even think about using metal plates in the way described in a normal microwave oven and don't use a microwave/convection oven in microwave mode. If you do and a metal plate is used, you run the risk of blowing the oven's magnetron. On balance, we think it would be better to use a conventional oven. Notes & Errata Traffic Light Simulator, February 1993: the wiring diagram on page 25 shows the two ICs oriented in the wrong direction. In addition, the circuit of the train controller on page 27 shows incorrect connections to the polarity changeover switch, S2. It should be wired as shown in accompanying diagram. FORWARD S2a REVERSE TO TRACK FORWARD REVERSE S2b ORDER FORM .... . ... BACK ISSUES* MONTH YEAR YEAR MONTH MONTH YEAR MONTH VEAR *Back issues are $AS each (incl. postage). Overseas orders add $A1 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 D r------------7 New subscription - month to start D Renewal - I I I I I I I I I I D Gift subscription ~ Sub. No. RATES (please tick one) 2 years (24 issues) Australia D $A84 Australia with binder(s)* 0 NZ & PNG (airmail) D $A130 D D D D D $A105 Overseas surface mail 0 $A130 Overseas airmail D $A240 1 year (12 issues) $A42 $A53 $A65 $A65 $A120 *1 binder with 1-year subscription; 2 binders with 2-year subscription I ,.. I VOl,JR DETAILS Your Name (PLEASE PRINT) Address I I I I I I GIFT SUBSCRIPTION DETAILS Month to start Message Gift for: Name State rL _ _ _ _ _ Postcode Daytime telephone number 0 Cheque/Money Order Card No. ~ (PLEASE PRINT) Address I I I I I I I I I I I I I I Postcode I I _ _ _ _ _ _ _ .J Signature D Bankcard D Visa Card D Master Card I I I I I I I I I I I I I I I I I I I I Phone (02) 979 5644 Fax (02) 979 6503 9am-5pm Mon-Fri . Please have your credit card details ready Fax the coupon with your cred it 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 pcstage stamp requ ired in Australia MA Y 199 3 93 . . . . .TCENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. r-------------------------, ANTIQUE RADIO CLASSIFIED ADVERTISING RATES ANTIQUE RADIO RESTORATIONS : specialist restoration service provided for vintage radios, test equipment & sales. Service includes chassis rewiring, recondensering, valve testing and mechanical refurbishment. Rejuvenation of wooden, bakelite & metal cabinets. Plenty of parts - no catalog require details for mail order. About 1200 radios within 16,000 sq ft. 2-year warranty on full restoration. Open Sat 10am4.30pm; Sun 12.30-4.30pm. 109 Cann St, Bass Hill, NSW 2197 Phone (02) 645 3173 BH or (02) 7261613AH. Advertising rates for this page: Classified ads: $10.00 for up to 12 words plus 50 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 in the space 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. . WANTED WANTED!: Toshiba EHT transformer part no. TFB3003B to suit C-2020 colour TV. Phone (057) 83 2227 any time please. FOR SALE Enclosed is my cheque/money order for $_ _ _ _· or please debit my □ Bankcard □ Visa Card □ 0 Master Card J LL =u L__IL__L__c____JI I~~ ~ XI I I Signature _ _ __ _ _ _ _ _ _ _ Card expiry date_ __c/_ __ I I Name _ _ __ __ _ _ _ _ _ _ __ _ _ _ _ _ _ __ _ I I Street _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ __ _ _ _ __ I Suburb/town _ _ _ _ _ _ _ _ _ _ _ Postcode _ _ _ _ __ I L _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ JI Card No. 94 SILICON CHIP WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" $35 is a high resolution, shortwave fax, Morse & RTTY receiving program . Suitable for CGA, EGA, VGA and Hercules cards (state which). Needs SSB HF radio & Radfax . decoder. *** "SATFAX" $45 is a NOAA, Meteor & GMS weather satellite picture receiving program . Needs EGA or VGA plus "WEATHER FAX" PC card. *** "MAXISAT" $75 is similar to SATFAX but needs 2Mb expanded memory (EMS 3.6 or 4.0) and 1024 x 768 SVGA card. All programs are on 5.25-inch or 3.5-inch disks (state which) & include documenti:ltion. Add $3 postage. Only from M. Delahunty, 42 Villiers St, New Farm , Old 4005.'Phone (07) 358 2785. THE HOMEBUILT DYNAMO: (plans) brush less, 1000 watt at 740 revs. $A85 postpaid airmail from Al Forbes, PO Box 3919 - SC , Auckland, New Zealand. Phone Auckland (09) 818 8967 any time. BURGLAR ALARM KIT: Control panel (no case) $180.00; Remote Keypad SURPLUS COMPONENT SALE STOCK QTYS LIMITED, NO BACK ORDERS 2N3055 $1.20 RESISTORS TIP30C $0,50 MOST VALUES AVAIL TIP122 $1.20 1/4W M/FILM $3/100 2N7000 $1.50 1/3W CARBON $2/100 2SC2240 $0.60 1/2W CARBON $4/100 VN88 $2,00 1WCARBON $5/100 3N170 $1,50 2W CARBON $8/100 2N5954 $1 ,50 SW WIREWOUND $0.30 2N3440 $1.20 1OW RESISTORS $0,60 CONNER 120MB IDE HARD DISKS $525,00 KEYTRONICS KB 3270PC KEYBOARDS $220.00 HEWLETT PACKARD 545A LOGIC PROBE $55 HEWLETT PACKARD 546A LOGIC PULSER $75 ONE ONLY H.P, CURRENTTRACER 547A $75 ONE BWD 245A DUAL POWER SUPPLY $450 VALVES 1.44MB FDD $95.00 3A4 $8,00 1MB SVGA $125.00 417A $8.00 CHECKIT PRO $179.00 5651 $8,00 MOC3020 OPTO $2,00 5R4GY $8.00 MOC8050 OPTO $1.50 EL32 $8.00 74C161 $2.00 ONE ONLY TBL 12/30 TRANSMIT TUBE $2700,00 PHONE OR MAIL ORDERS, CREDIT CARDS ACCEPTED FOR ORDe'RS $20 & OVER, DISCOUNTS FOR QUANTITY ORDERS SECONTRONICS PO BOX 2215, BROOKSIDE, QL04053, PHONE (07) 3551314 143 GRAYS RD, ENOGGERA, QLD 4051, FAX (07) 8551014 SHOP OPEN SATURDAY 9AM • 4PM AH (07) 855 1880 $45.00; P&P $16.00. Michael Zenere, 7 Hayfield Rd, My Waverley, Vic 3144. Phone (03) 803 1831. SINGLE CHIP MICROCONTROLLER: 1.8K Eprom. 1-10 = $13.00 ea; 11-100 = $12.00 ea. P&P $2.00. Michael Zenere, 7 Hayfield Rd, My Waverley, Vic 3144. Phone (03) 803 1831. UNUSUAL BOOKS: electronic devices, fireworks, locksmithing, radar invisibility, surveillance, self-protection, unusual chemistry and more. For a complete catalog send 95c in stamps to: Vector Press, Dept S, PO Box 434, Brighton SA 5048. KIT REPAIRS & CONSTRUCTION service. Fixed price servicing for all kits. No job too small. Ph (02) 649 2134 after 5pm. VARIAC 0-280VAC: 8-amp Warburton Franki type W20. Hardly used. $200. Minto (02) 820 2244. ADD A CIRCLE PATTERN to SILICON CHIP's colour TV pattern generator. Fully assembled and tested PCB with mounting hardware and installation instructions. Easy to install. $45 includes postage. Placid Talia, 37 Kionga St, Clayton 3168. Phone (03) 720 7700, AH (03) 543 3561. DON'S PROMO DISK: $2 (720Kb 3.5inch IBM). Little kits & tiny computers: Printer Port Expansion kit, 4Mb Printer Buffer, Z80 Development Board, I MEMORY & DRIVES ICL 286 Board PRICES AT MARCH 23RD, 1993 All in one board with two serial, printer, IBM keyboard, highdensity lloppy & IDE mono video interface. Up to 4Mb RAM, 80286-16cpu, MS-DOS compatible, 130 page manual, small size 170mm x 255mm. Laptop power supply 240V 5V/ 3A 12Vr3A $89 $299 lnlrared sets, 1 each IR LED, diode & IDC header $1 Ampro little PC Audio IChybrids STK043-25 or STK058-40W $9,95 SIMM 1Mbx9 ?Ons 4Mb (72-pin) 4Mb x 9 ?Ons 4Mb x 8 80ns DRAM DIP 1 x 1Mb 256 X 4 41256 1Mbx4 $53 $210 $210 $195 ?Ons $6,00 $6,25 ?Ons $2,50 80ns ZorD $24.00 DRIVES SEAG 42Mb SEAG 89Mb SEAG 107Mb SEAG 130Mb SEAG 245Mb 28ms 14ms 15ms 16ms 12ms $240 $322 $350 $375 $635 IBM PS,2 50/55(70 70/35 90/95 2Mb 4Mb 4Mb $130 $220 $220 TOSHIBA T3200SX T44/6400 T5200 4Mb 4Mb 2Mb $270 $240 $150 MAC 2Mb s1 ·& LG 4Mb P'Book $108 $270 CO-PROCESSORS 387SX 20/25 IIT $130/5 387DX All Intel $140 EPROMS 27C 4Mb15 $16 Sales tax 20%. Overnight delivery. Credit cards welcome, All in one NEC V40 CPU board, MS-DOS compatible, highdensity floppy, SCSI hard disk, 2 serial, printer, solid state hard disk, IBM keyboard interface, (4W), CMOS single +SV rail, up to 768Kb RAM, 384Kb ROM, 145mm x 250mm, 98-page manual. $299 Ring for Latest Prices 1st Floor, 100 Yarrara Rd, PO Box 382, Pennant Hills, 2120. Tel:(02)9806988 Fax: (02) 980 6991 pivTHr A ""AH L'.JL rllt'.i TRANSFORMER REWINDS .,> Fujitsu 40Mb hard disks $269 Microbyte-PC230 v30 CPU board, t Mb RAM installed, 2 serial, printer, 720Kb floppy, SCS1 hard disk, EGA video, IBM kb interface, made in Australia, surplus $185 ea ALL TYPES OF TRANSFORMER REWINDS 720Kb Floppy Drives $55 TRANSFORMER REWINDS 1.44Mb Floppy Drives $89 Reply Paid No.2, PO Box 438, Singleton, NSW 2330. Ph: (065) 761291. Fax: (065) 761003. '/le buy surplus computer & electronic products, bankrupt stock and components. P. C Computers ACTIVE DISTRIBUTORS REQ'D AUSTRALIA & NEW ZEALAND UCANDO VCR EDUCATIONAL PRODUCTS COMPANY Unique copyrighted animated UCANDO videos for electronics & digital/computer training . USA sales US$6,000,000 year. Also sold in UK & Europe. PO Box 4603, Christchurch, New Zealand. Ph/Fax 3 379 5570. • • Bargains Taped components by the metre app 200pcs, tants, caps, zeners, diodes, resistors $5,95/metre 600-600 ohm audio output transformers PCB mount 18Hz38kHz. $9.95 Kits Max 1/0 kit for PCs, 7 relays, ADC, DAC, stepper driver, TTL inputs, with software $169 PC 1/0 card with 8255 chip 24 1/0 lines programmable as inputs or outputs $69 1.5 watt AM broadcast transmitter XTAL locked $49 2.5 watt FM broadcast transmitter 88-108MHz. $49 Digi-125 audio power amp(over 19 ,000 sold since 1987) 50 watV8 $14 125 watt/4 $19 New 200 watt/2 version $29 lnlrared relay kit $9 Remote control tester $4 36 Regent St, Kensington, SA. Phone (08) 332 6513, FIX-A-KIT KIT REPAIR & CONSTRUCTION 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION TECHNICAL ASSISTANCE HVCAL ELECTRONICS Design, Manufacture & Repair of Electronic Equipment (02) 633 5477 Amstrad Notepad, Atari Portfolio, and lots more. Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. Phone (03) 338 6286. GATES BATTERIES: famous GATES batteries at a giveaway price. We have a limited quantity of BRAND NEW 4V dual cell 5Ah gel batteries at a giveaway price of $10 per pack: DON'T MISS OUT AND WHINGE AFTERWARDS! HIGH INTENSITY LEDs: high intensity narrow angle 5mm red LEDs in a clear housing, with a luminous power output of around 1000mCD <at> 20mA. That's more than 1000 times brighter than normal red LEDs. SPECIAL INTRODUCTORY PRICE of 50c ea. or 10 for $4, or 100 for $30. UNBELIEVABLE! GLASS PRISMS: a pair of very large precision glass prisms that were removed from tank night viewers. One surface of one of the prisms was exposed to the weather and is contained in an aluminium housing, whilst the other was sealed within the viewer. Very heavy! Limited stock at $26 per pair. IR PHOTOINTERRUPTER: an IR LED and an IR transistor in a slotted PCB moul)ting assembly. The discrete components are easy to separate, as the assembly clips together. Great for IR experiments, $2 ea. or 10 for $15. 1INCH CRO TUBE: new 1-inch CRO tube plus a connecting diagram, plus a simple experimental circuit. Very limited quantities. CLEARANCE <at> $20. SWITCHED MODE POWER SUPPLIES: brand new complete assem- MA Y 1993 95 LOCAL TRADES & SERVICES Advertising Index Altronics ... .... .. .. ...... .... .. . IFC,60-63 T. A. Mowles Transformer Rewinds Printed circuit boards for the hobbyist. For service & enquiries contact: For all types of transformer rewinds. (08) 3265590 (065} 761291 Fax (065) 761003 Antique Radio Restorations ...... 94 A-One Electronics ... ... .. .. ...... 76,77 Av-Comm ... ..... ... .... ..... .... .. ...... .. 54 Coman ... ... ... .... .. .. .. .... ... ........ .. .. 89 David Reid Electronics ....... ......... 3 Dick Smith Electronics .... ..... 24,25 Silicon Chip EEM Electronics · To advertise your products or services, please call Sharon on Printed circuit board assembly, switchmode power supplies repaired. Design work from start to finish. Ring anytime 9am-9pm Mon-Sun. (02) 9795644 (018) 285532 (03) 4011393 EEM Electronics .. ............. ..... .... 96 Harbuch Electronics ... ...... ... ...... 43 Hewlett Packard ... .. ..... ..... .... ... IBC Jaycar ... ... .... .......... ..... ......... 45-52 JV Tuners ..... ... .... .. ...... .... .......... 43 Kalex .... ............ .... ..................... 59 closed in a small black metal case. blies consisting of a large PCB on an Lshaped aluminium heatsink. Overall diContains a small battery (G13) and a mensions 260 x 230 x 70mm - large! microphone; 32 x 23 x 11mm! Bargain at $32. FM MICROPHONE: features a 110/240V input. Outputs +5V, -5V, + 12V, -12V. We have no further specs but unit stainless steel case and a unidirectional appears to be of a much higher power microphone insert, powered by two AA batteries. High quality at $32. DYNAMIC rating than a typical computer power MICROPHONE: stage quality 600-ohm supply. Circuit provided. LIMITED QUANTITY <at> $25 ea. FANS: brand · dynamic microphone in a black metal case $39. ELECTRONIC KEY: use it to new German-made PAP ST brand 115V activate door strikers for entering build12W fans with metal blades. Overall dimensions 80 x 80 x 38mm. Use two in ings, for switching car alarms, central locking, the most secure key ever (see series to run off mains? Only $14 ea. EA July 1992) . On special<at>$49.90 for UNUSUAL ITEMS & COMPONENTS: two keys & one decoder kit. Major cards 20kV PIV 5mA av/1 A pk fast diodes $1 .50ea; 3kV PIV 300mA/30A pk fast accepted with phone & fax orders. Total diodes 60c ea; 30V PIV 1A/23A pk cost of certified P&P in Australia $5; in NZ (airmail) $10. Oatley Electronics, Schottky Barrier diodes 45c ea. 680pF/ PO Box 89, Oatley, NSW, Australia 3kV disc ceramic capacitors 30c 2223. Phone (02) 579 4985. Fax (02) ea.1000pF/15kV disc ceramic capaci570 7910. tors $5 ea. 0.01 µF 5kV disc ceramic capacitors $1.80 ea. Flexible DECIMAL KEYPADS with PCB connectors to suit $1 .50 ea. High quality UNIDIRECRC§ RADITO PTY LTD TIONAL ELECTRET microphone inserts $8 .50. Stage quality UNIDIRECTIONAL DYNAMIC microphone inserts $9 .60. 100 LED BARGRAPH DISPLAY: yes 100 LEDs plus IC control 6 circuitry, all surface mounted on a long strip of PCB. A4-bit binary code selects RCS Radio Pty Ltd is the only company that manufactures and sells which one out of the 10 LED groups will every PC board and front panel be on, whilst another 4-bit binary code selects which one of each group of 10 published in SILICON CHiP, ETI and LEDs will be on. Latching inputs are EA. also provided. We include a circuit and RCS Radio Pty Ltd, a connecting diagram . VERY LIMITED 651 Forest Rd, Bexley 2207. QUANTITY <at> $7 ea. MINIATURE FM Phone (02) 587 3491 TRANSMITTER: ready made and en- ~i~1,~ 0°i Ui!-ol Ill ::;=J 96 S1ucoN CwP I Kenwood Australia ... .. ... ..... .... OBC Oatley Electronics ........... 31,69,95 PC Computers ... .. ....... ............. . 95 Pelham ..... .. .... .. .. .... .... ... .... .... .... 95 Peter C: Lacey Services ... .. .. .... 40 RCS Radio ........... ... .. .... ... ...... ... 96 Rod Irving Electronics .. ..... ... 10-15 Secontronics .. ..... ..... ... .... ...... .... 95 Silicon Chip Back Issues .. .. .. 84,85 Silicon Chip Binders ..... .... ......... 58 T. A. Mowles ... .... ..... ............ .. .... 96 Technical Applications .... ....... .... 41 Transformer Rewinds ............ .... 96 Ucando ... ......... .. ...... ... .... ....... .... 95 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • ~emal Products, 5 Forge St, Welshpool, WA 6106. Ptione (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone (09) 828 5730. • RCS Radio Pty Ltd, 651 Forest Rd , Bexley, NSW 2207. Phone (02) 587 3491. You Didn't Think You Could Afford HP, Did You? Think Again. The value of this 100MHz scope is easy to see. The HP54600 gives you superior viewing of virtually any waveform, even at low rep rates and slow sweep speeds. It looks and feels like an analog scope, with dedicated knobs and a display that responds instantly to your control changes. And it has the digital power that analog can't give you - high accuracy, automatic measurements, hard copy output and programmability. But what really stands out is that all this performance costs just $4,840 (4-channel) or $4,170 (2-channel). * What's more, now through June 30, 1993, you can add FIT by purchasing an HP 54657A or 54658A Measurement/ Storage Module for only $625. For more information call our customer information centre on 131347. We are happy to send you literature. FFT is just one of the advanced waveform viewing tools you'll get with the HP54657A/58A Measurement Storage Module. • PR ICES EXC LUDE SALES TAX F/,pl HEWLETT ~~ PACKARD