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MARCH 2001  1 el od m EX by ol D ew N AV Receiver of theYear The SR-18 delivers 140 Watts of Judges’ comments: “For premium pure, clean THX® power to each of home theatre the SR-18 is quite its five channels. It features Dolby® simply the highest powered, most Digital and also DTS® processing, fully featured multichannel AV and enough digital/analog inputs AV Receiver of the Year receiver available.” and outputs to handle even the most This unabashed praise for the Marantz sophisticated home theatre system. SR-18 by the ‘Sound & Image 2000’ Judges led to it being For your free information kit on the awarded the ‘AV Receiver of ‘AV Receiver of the Year’ or any of the the Year’*. other five Marantz Dolby® Digital Surround This award comes hot on the Sound receivers, please contact the Best Audio Product heels of another recent industry sole Australian Marantz distributor, award. At the prestigious ‘CEDIA 99’ QualiFi Pty Ltd, FreeCall 1800 24 24 26 show in the USA, the SR-18 was also or e-mail us today on info<at>marantz.com.au awarded the ‘Best Audio Product’† of the year. http://www.marantz.com * † 2  Silicon Chip *Over $2000. †Cedia Electronics Show 1999. “DOLBY DIGITAL”is a trademark of Dolby Laboratories Licensing Corporation. DTS is a registered trademark of DTS Technology. THX is a registered trademark of Lucasfilm Ltd. QLF059 Contents Vol.14, No.3; March 2001 FEATURES 7 What’s On Offer In “Walkie Talkies” They’re great for short range work. Here’s a look at what’s available and what you should look for – by Ross Tester 14 Mobile Magic: Driving Your Mobile Phone From A PC A PC makes it to easy to send messages, edit phonebook entries and create logos and ring tones. You can even use your mobile phone as a modem to send faxes and email – by Greg Swain 20 Using Infrared Devices With Your PC You don’t have to jump through hoops to get infrared working on your PC. Here’s what you have to do – by Greg Swain 26 Review: Marantz DR 6000 CD Recorder You don’t need a PC; use this to copy to CR-R and CD-RW disks instead. It also works as a very fine CD player – by Leo Simpson Mobile Magic: Driving Your Mobile Phone From A PC – Page 14. 29 CB Radio Can Now Transmit Data Data transmission is now permissable on UHF channels 22 & 23 70 Making Photo Resist PC Boards At Home A step-by-step technique for making pro-quality PC boards from laser prints or copies – by Ross Tester Big-Digit 12/24 Hour Clock With Bright LED Display – Page 30. PROJECTS TO BUILD 30 Big-Digit 12/24 Hour Clock It’s large, it’s bright, it’s very accurate and can be used in either 12 or 24-hour mode. A PIC processor powers the works – by John Clarke 44 A Sun-Seeking Sunflower It senses where the Sun is and automatically turns towards it. A couple of solar cells power the circuit and drive the motor – by Ross Tester 62 Parallel Port PIC Programmer & Checkerboard Easy-to-build unit not only programs PICs but includes useful test facilities as well – by David Deer 81 Protoboards: The Easy Into Electronics More fun with comparators: making a window comparator – by Leo Simpson 84 More-MIDI: A Simple MIDI Expansion Box It takes one MIDI signal and feeds it to four separate outputs – by Jim Rowe SPECIAL COLUMNS Sun-Seeking Sunflower: it follows the Sun – Page 44. 58 Serviceman’s Log Meet me on the reset line – by the TV Serviceman 88 Vintage Radio The 1929 AWA C58 radiogram – by Rodney Champness DEPARTMENTS 2 4 28 42 57 Publisher’s Letter   98 Mailbag 100 Circuit Notebook 101 Product Showcase 102 Subscriptions Form 104 Ask Silicon Chip Notes & Errata Electronics Showcase Market Centre Advertising Index More-MIDI: Simple MIDI Expansion Box – Page 84. MARCH 2001  1 PUBLISHER’S LETTER www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Peter Smith Ross Tester Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Rick Winkler Phone (02) 9979 5644 Fax (02) 9979 6503 Mobile: 0408 34 6669 Regular Contributors Brendan Akhurst Louis Challis Rodney Champness Garry Cratt, VK2YBX Julian Edgar, Dip.T.(Sec.), B.Ed Mike Sheriff, B.Sc, VK2YFK Philip Watson, MIREE, VK2ZPW Bob Young SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490 All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $69.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 8, 101 Darley St, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. E-mail: silchip<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip The electrical wiring debate – reform is needed This on-going debate about the whys and wherefores of people doing their own home wiring actually started in the June 2000 issue when a letter raised the concern that it was illegal for people to build or repair mains-operated kits unless licensed by the Queensland Electrical Licence Board. Since then the issue has developed to embrace the idea that anyone should be able to do electrical wiring in their own home, just as they in New Zealand. In the 13-plus years of SILICON CHIP’s history, no issue has ever generated as much correspondence and most of it, I have to say, has been well-considered: some for the status quo and some for the idea that homeowners should be allowed to do it. It has also become clear that one of the reasons why the Queensland Electrical Licensing Board is attempting to be so draconian is that they are concerned with the apparently high number of deaths by electrocution in that state. Whether or not a large proportion of these deaths have come about because of illegal home wiring is not clear However, it is now becoming apparent that in its on-going review of the situation, the Queensland ELB has the intention of instructing licensed electri­cians to look for and report any instances of “illegal” home wiring that they come upon. Supposedly, the perpetrators would then be fined or otherwise penalised. When I heard about this I was flabbergasted. Is this really happening in Australia? Surely not! If this is true, it will have exactly opposite the desired effect. Say you want some extra wiring done in your house but maybe you or someone else has added wiring in the past. Say it’s all done by the book but it’s really neat. Now, if you get an electrician in, will he identify the neat wiring as being illegal? Because it’s neat and obviously not done by any normal electrician? And what’s the likelihood of an electrician identifying any wiring as suspect? Even if it was done by another electrician? Even if you keep receipts, it would not identify particular wiring. And what if a previous electrician has made a mistake or taken a short-cut? How would any householder know if this has happened? No this whole idea of using licensed electricians to ferret out illegal wiring is crazy. It is more likely to force people to do their own wiring or have it done by someone (unlicensed) on the quiet. It will backfire on the Queensland Electrical Licens­ing Board. Their job should be to educate the public (and licensed electricians) and do everything possible to promote a safe elec­trical distribution system. You don’t achieve that by having electricians report on their own customers. It won’t take long for electricians to figure that out! The more we think about and discuss this issue, the more we think the regulations should change to allow homeowners to do their own wiring, subject to subsequent inspection (probably by licensed electricians). In fact, we plan to proceed down this path and hope to publish a petition next month to get the politi­cians moving. Watch for it next month. Leo Simpson                                                                                                                                                                                                                                                      Look Mum - No Wires & 11Mbps!                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   We welcome Bankcard, Mastercard and VISA NO SURCHARGE! Website, online catalogue & shop: www.mgram.com.au Phone: (02) 4389 8444 sales<at>mgram.com.au   info<at>mgram.com.au    Fax: (02) 4389 8388    FreeFax: 1 800 625 777 MicroGram Computers    Unit 1, 14 Bon Mace Close, Berkeley Vale NSW 2261 Vamtest Pty Ltd trading as MicroGram Computers ABN 60 003 062 100. MARCH 2001  3 MGRM0301 All prices subject to change without notice. MAILBAG LP Doctor’s input stage Paint me shocked or have you people learned nothing in your years in the magazines? Look at your RIAA preamplifier in your LP Doctor (January & February 2001). Is anything wrong with it? The variable impedance of the RIAA filter will be reflected into the input, the cartridge! Result equals distortion! The only cure that I know of is to interpose an amplifier between the filter and the input socket. For a test, try a source follower in that place and listen to the improvement! David Till­brook wrote of this with his Series 5000 preamplifier (ETI, July 1981). This was a seminal article in the annals of hifi. Bob Phelps, (via email), Comment: the input impedance of the LP Doctor is 50kΩ shunted by 100pF (plus input cable capacitance) which is close to ideal for the majority of magnetic cartridges. The RIAA feedback network does NOT reflect back to the non-inverting input stage. The result is low distortion, as measured. Tips for dubbing onto CDs Let me compliment you on the LP Resurrection article in the January 2001 issue. It provides comprehensive coverage on what is an extremely complex topic if you really get into it. I have a couple of points which might assist readers when using the various pieces of software. When using Adaptec CD Creator, it is essential to use the “Disk at Once” option. This allows CDs to be played on those players which have any type of anti-shock memory system; ie, in a car or a portable. Using the other options will enable disks to be played on the majority of home decks but not on those with memory as mentioned above. When the other options are used, these players just sit there after the first track and wait for you to press the track advance button to proceed through the disk. Not using this option can also cause a “glitch” when chang­ing tracks if the CD is played back on standard CD players. It could be the closing of the disk or the fact that the laser turns off between tracks that causes this (I believe it is due to the latter). 4  Silicon Chip The other point that your readers should be aware of is that when using SoundForge 4.5, the minimum graphics card memory is 8Mb. Less than this causes the audio to stutter when playing the wave file at some magnifications. SoundForge also requires a reasonably fast PC, say a Pentium II 333, with 128Mb RAM to really fly properly. This kind of system is a bit “old hat” now but still adequate for most applications. If you have the hard drive space available I’ve found it preferable to record the whole side of the LP at once and then split it up after level matching, EQ, etc. This enables you to find the loudest point on both sides of the LP and gain match each side appropriately so as not to go over the magic 0dB level. Doing this keeps both LP sides level in relationship to each other throughout all the tracks rather than one track at a time. Brad Sheargold, (via email). C too difficult for PIC programming The PIC Programmer & TestBed in the January 2001 issue is an excellent idea, providing the hardware options required for simple program testing. However, using the MPLAB all-inclusive software (free) might prove a bit too much for beginners, who have no experience with assembly language or the ‘C’ language. Assembly coding is always a bit tedious and it is usually better to use a “user-friendly language” compiler. My introduc­tion to the PIC world was through the BASIC Stamp modules, which provided user-friendly programming and were very simple to use. Unfor­tunately, these units are relatively expensive and so I use the PIC16F84 for small projects. My programming board is a kit obtained from Jaycar (Cat KD-6062), which connects to a PC parallel port. I use the PicBasic Compiler, which has an enhanced version of the BASIC Stamp1’s programming language. This software is from MicroEngineering Labs and came from Microzed Computers. The creation/editing of programs is done using any text editor, using filenames with the .bas extension. Simplest is the DOS Edit screen, which can be called from within Windows by using Start/Run Edit. The actual encoding of the PIC is achieved using the “P16PRO Light” software, a free download for home users, at www.allofmaine.com/picprogrammer/#p16prolight This is a DOS program but it is easy to use inside Windows, opened from the desktop using a shortcut icon. The compiler, P16PROL, and all associated files are held in one directory and the compiler is called using the Windows Start/Run facility (Start/Run: “C:\progra~1\pbc\pbc filename”). This will produce .hex and .asm files from the original .bas file. The only real downside to using the PBasic Compiler is the lack of Debug support, as is available in the Stamp1, but this is not a problem with simple programs. I usually sort out any prob­ lems by setting up temporary software traps outputting to I/O ports (eg, operating LEDs). The PBasic Compiler also allows sections of Assembly lan­ guage to be inserted inside the program. It supports the Basic “Peek/Poke” commands and read/write of external serial EEPROMs. Although it was necessary to pay for the compiler ($A132), it has proved to be a good choice. Ken McCarroll, (via email). Biorecognition accuracy and security Your article on biorecognition in the January 2001 issue was interesting but very light on technical information. Whilst it lists 10 different biometrics, it only describes (fairly briefly) two of them. One critical area that the article failed to address is the accuracy and reliability of the different techniques. Bio­metric authentication can fail in at least three different ways: false negatives (incorrectly denying access), false positives (incor­rectly allowing access) and the probability of two people having the same biometric signature (especially in the case of identical twins). Providing an acceptably low error rate is a major impedi­ment to the wider deployment of this technology. The claim that the device is secure against penetration because it can’t allow access if it is ripped off the wall also fails to address electronic penetration. As a networked device, it (and the master database) also needs to be secured against unauthorised access from other devices on the network. The provi­sion of modem access just expands the opportunities for an un­authorised person to gain access. Finally, a quick comment on your wireless LAN article in the same issue. Whilst wireless LANs have many benefits, security is (in general) not one of them. Radio waves do not recognise corporate boundaries and by default most wireless LANs will allow any suitably equipped PC to join the network. Do you really want someone across the road reading (or even chang­ing) the files on your network? Peter Jeremy, (via email). Comment: although not mentioned in our article, the wireless LAN described uses frequency hopping technology and, for even greater security, also allows you to encrypt transmissions. Informed enthusiasts have always done their own wiring I’ve been reading the opinions concerning the electrical licensing debate with great interest and entirely agree with what you have said on the matter. Brian J Spencer’s letter in the January 2001 issue appears to suggest that an increase in electrocutions and fires will result if the present regulations are scrapped. I fail to see any reason for this, simply because ‘non-qualified’ people have been doing their own wiring since electricity became available for domestic use, and they will continue to do so. It’s the same with other services like phone and water. Go into the house of most electrically/electronically mind­ ed people and there’s a good chance that the phone and mains wiring has been modified and not by ‘qualified’ personnel either. The reality is that most of these jobs are of good workman­ship and pose no threat to safety. Of course, you do get some really dumb mistakes, particularly with light fittings because of the loop connection, but in these situations the would-be elec­trician gives up and does in fact call an electrician to sort out the mess. I have read more overseas electronic magazines and DIY books than I can remember and it is normal for the homeowner to legally do their own wiring in most places. It would be interest­ing to see statistics from the UK and NZ (as they have 240VAC too) to see how the rate of electrocutions and fires compares to Australia. I somehow think there will be minimal difference because the facts are that people will continue to do their own wiring if they feel knowledgeable enough to do so, whether it’s legal or not. Most people do have a fear of touching any wiring and rightly so, if they don’t understand it; for these people, having someone qualified to do the job will not change. John Hunter, (via email). The New Zealand electrical wiring experience I was interested in your editorial in the November 2000 issue in that anyone should be able to do their own house wiring, quoting the NZ experience. Over here they realised that in allow­ing one to do various electrical jobs around your house they still required you to get the work checked by an Electrical Inspector before connecting to the 240VAC supply and before a Certificate of Compliance is issued. We are also allowed to do limited plumbing work but not drain laying or connecting to the sewer, etc. Also there is some talk of allowing suitable applicants who are not in the relevant trades to obtain a limited wiring certificate or something simi­lar to enable people who meet the relevant criteria to do elec­trical work legally. W. Davis, Auckland, New Zealand. The WIA in the 21st Century For some time I have been concerned that the Wireless Institute of Australia (WIA) as it is currently structured does not, and cannot, work in the best interests of radio amateurs. To promote discussion and initiate change I have prepared a paper showing why the WIA’s current organisation is not suitable for dealing with the issues facing Amateur Radio in the 21st Century and stating how it should be changed. I have held an amateur radio licence since 1966 and have been involved with the WIA at State council level in two states and as a national director. Since the WIA’s peak in membership of over 8000 in 1982 there has been a steady decline to about 4500 members. This decline has occurred while there has been recruitment of new members. The WIA organisation seems unwilling to face the prob­lem. Blame is attributed to external factors such as a declining interest in Amateur Radio. The facts are that more radio amateurs have left the WIA since 1982 than are currently members! Motions to change the WIA at Federal Council have been defeated. The last was not even allowed to be discussed. If the elected officials of our organisation are unable or unwilling to make the necessary changes then the members themselves must make their views known. The organisation has become negative and defensive with no real goals and objectives. People who have a vision of bettering amateur radio find themselves frustrated. The WIA office is still in Melbourne yet we deal with the ACA based in Canberra. One of the smallest allocations in the WIA budget is for ACA liaison. A strong national approach is required if Amateur Radio is to continue far into the future. Martin Luther, VK5GN, Willaston, SA. The detailed paper is available via email from luther<at>mail.mdt.net. au or at http://www.alphalink.com. au/~parkerp/wianat.htm In defence of Vintage Radio I have had an interest in vintage radios for some time now and find restoring the great old radios a rewarding pastime. If it wasn’t for people like myself who take the time to restore MARCH 2001  5 Mailbag – continued . . . these radios how would our younger generation understand where modern technology has come from? This is all a part of our his­tory and we all seem to want to learn about our past. If you don’t believe me, then why do we have museums, antique collec­tors, restorations and people tracing their ancestry, etc? If vintage radio is old hat, then why do some of the younger generation come to me for advice and assistance in repairing various items? I’ve got my favourite old hat and I wouldn’t get rid of it for quids! Leo, it wasn’t that long ago you were telling us not to throw those old black and white TVs away as in 20 years or so the young people won’t know anything about them. I agree with your views on this. K. Lang, Esperance, WA. Vintage Radio is important Your correspondent Alfred Fischer seems to have missed the point regarding the value of the Vintage Radio pages in SILICON CHIP. To condemn Vintage Radio to the rubbish bin because it is past its “use by date” is to condemn history. Nobody would sug­gest that we revert to valve technology for current electronic applications but to ignore this important period of our electron­ic history is to ignore the efforts of the pioneers in theory, design and manufacturing on which much of our modern electronics is based. If we were to use this philosophy for every field of engi­neering endeavour that is superseded by new technology, we would have no interest in old cars, aircraft, buildings, etc and an important part of their history would also be lost. The “revival of corpses” that Mr Fischer refers to is in fact the preservation of important examples of Australia’s and the world’s electronic history. It should be remembered that from the early 1920s to 1975 Australia had a vibrant radio, and later TV, manufacturing indus­try with over 50 companies at its peak employing many thousands of people. From the earliest days Australia’s isolation ensured that a significant number of developments in the field of radio were “home grown”. With over 900 members, many of 6  Silicon Chip them SILICON CHIP readers, the HRSA is active in promoting the preservation and restoration of these important examples of our electronic heritage. The valuable information contained in the Vintage Radio pages of SILICON CHIP and other magazines encourages newcomers to the hobby and helps to awaken an awareness in others that we should preserve, rather than scrap, as many examples of radios of the period as possible. I would like to extend an invitation to Mr Fischer to attend one of our regular meetings and see for himself that there is more to Vintage Radio than he may think. Warwick Woods, President, Historical Radio Society of Australia Inc. Rodney Champness has his say Alfred Fischer’s email in the January 2001 “Mailbag” is provocative. Certainly he is entitled to his view and by express­ing it, he may invoke others to really think about their inter­ests in all sorts of things. However, I’d like to put a few points in favour of Vintage Radio and other historical interests shared by hundreds of millions of people throughout the world. Should we pull down all the magnificent castles and cathe­drals in Europe? Should we use the rubble from the great pyramids of Egypt to make a new highway along the Nile valley? While we’re about it, how about using all of the vintage and veteran cars as land fill or perhaps melt them down to make tower cases for computers? Isn’t this what Alfred Fischer would have us do with our history and heritage? Certainly, I write the Vintage Radio column but I do have other interests in the electronic field. I work with computers, programmable logic controllers, ICs and transistors, MF, HF, VHF and UHF equipment, satellite receivers and (would you believe it?) valves. I am a great believer in appropriate technology and although valves are used in very few things these days, they are still used. However, solid state is more appropriate in 99% of applications these days. I have just been asked to design and build an electronic timer for feeding liquid fertiliser into an irrigation watering system. It never occurred to me to use valves, as three ICs and a few transistors will do it all. I don’t agree that vintage radio is about the revival of corpses. It is about the evolution, social activity and history of radio in its various forms over the last century. It is about getting to know how valve radios (and transistorised ones too) worked, generally having fun doing it and being proud of what has been achieved. Just think how our ancestors designed things – have a look at the old engineering text books; it is incredible to see how things were done when, comparatively, resources were so limited. The point is we can learn much from our history whether it be vintage radio, vintage cars or what have you. By looking at history we can adapt some of the old ideas and by using new components we can achieve the best of both worlds. Rodney Champness, VK3UG, Mooroopna, Vic. Computer parts should be saved You suggested in your magazine not so very long ago that older computers that are no longer being used should not simply be dumped, if at all possible, as they can provide a useful source of spare parts. How right you were. Recently, I was in the middle of a session on a fairly new computer when I got that dreaded message that says, in effect: “Somebody had done a naughty thing and this computer will shut down” The cause of this catastrophe turned out to be a defunct CPU fan and hence an overheated CPU. The computer was only a little over 12 months old (just out of warranty). The computer down-time plus replacement costs of a rather expensive part was averted thanks to your advice. I had saved some parts from an older computer, including the power supply fan. The CPU fan was a 50mm type compared with the power supply fan which is an 80mm type so obviously I could not simply replace one with the other. To solve this problem, I made up an adaptor from fairly thin aluminium to mount the 80mm fan on the CPU heatsink. The computer has been running happily ever since. H. Nacinovich, Gulgong, NSW. Short Range Communications: What’s on offer in “walkie talkies”? They’re not exactly something you have to buy every day – but when you do, what do you look for? What’s available these days? What licences are required? Are they any good? A couple of months ago I was the local toy stores (seriously!). We Uniden equivalent. asked to look at small two- ended up with a reasonable range to But there are others out there. . . way radios suitable for sports look at, albeit covering only three or Licence requirements use. My brief was simple: find the four brands. most suitable radio for the purpose, There are many other brands with Everyone knows that you need some keeping in mind that budgets were similar specifications and its not form of licence to operate a radio trans(very!) limited. unreasonable to assume these would mitter, right? Well, that certainly used With an interest in radio going back perform much the same way as those to be the case but this is a new century to school days I thought this was go- we looked at. and the situation is somewhat changed. ing to be quite an easy task – after all, For example, we’ve seen Icom handIn fact, for a large number of users how many different types no licence is required. are there? But my invesNot one of the “CB” and tigations revealed quite “LIPD” two-way radios a number of variables looked at in this article which made the choice require a licence. We’ll that much more difficult. explain why shortly. While hand-held radios It’s only when you are not something SILICON want to have a frequenCHIP readers have to buy cy or channel that’s every day, we’re often exclusively yours that asked questions about raa licence is required. dios like these. And there This also means you are have been recent developmoving from “consumments you might not be er” into “commercial” aware of. So we thought equ-ipment which in our investigations might turn means significantly be of interest – if only higher prices. to let you know what is Our application was specifically for surf carnival control but we Obtaining frequencies available these days. that are yours alone can imagine many other sports would have similar requirements . . . This is by no means an also be rather difficult exhaustive comparison. these days – after all, We simply approached two of our helds with very similar features to the spectrum space is limited, especially advertisers and asked them what they Uniden models. We didn’t chase these, in the capital cities. There are other had available in hand-held radios. And mainly because the cheapest Icom options available – trunked systems for good measure, we also looked in unit was exactly twice the price of its for example – but once again these are By Ross Tester MARCH 2001  7 rather expensive options, way outside what we can afford. Trunked radio systems, by the way, have a number – often a large number – of users sharing the same channel through digitally encoded transmissions. The Sydney Olympic Games, for example, had a large trunked radio system in operation. Commercial users and organisations with big budgets do have a variety of choices – and there are plenty of suppliers who can help you out. Of course, using equipment shared with other users does mean that you (or they) have no “right” to use a particular channel, nor can you expect any remedy if someone interferes with you (either accidentally or deliberately). In the past, some CB radio users assumed “squatters rights” to a channel, particularly if they were using it for a business for some time and even more so if they were out in the country. If anyone dared to use “their” channel(s) they were told – literally – where to go! Of course, they had no legal right to do so – but who’s gonna argue with a 125kg truckie with a 20t truck behind him? Using short-range equipment tends to nullify a lot of the problems; using equipment with many available channels means there is much more likelihood of an “empty” channel. OK, so let’s get back to the type of radios we can afford. CB radio You’ve almost certainly come across the term “CB” before. But just in case you spent the last twenty years or so in a Tibetan monastery, CB stands for Citizen’s Band. Initially, Australian CB was limited to just a few channels, crystal locked in hand-held transceivers on the 27MHz band. 27.240MHz was probably the most popular channel. Then people started importing vehicle-mounting transceivers designed for the US Citizens Band with 23 channels. Wow! 23 channels! Oh yes, one minor detail: CB radios were also illegal. Ahh, the good old days! Then after much agitation – especially from truckies and CB clubs, CB radio was legalised. But the government, in its wisdom, decided upon an “orphan” system of 18 channels which shared most (but not all) of the old 23- channel frequencies. After a lot of pressure from importers (and also the fact that they hadn’t killed off 23-channel – and later 40-channel US-type CBs), the government relented and allowed the full 40-channel US system. In even more wisdom, they later decided to introduce another 40-channel CB radio band, this time centred around 477MHz. This was the “UHF” CB band. It was intended as a shortrange communications system without the “skip” of 27MHz CB which often meant CBers could talk to overseas users. (It’s still illegal to use a 27MHz CB to talk overseas). The other big change they made with this new CB band was that business and commercial use was allowed. While fairly limited in range, UHF CB found ready acceptance in country areas. Farmers, loggers, contractors – they flocked to it. It was relatively cheap, very reliable (within limits) and required no technical expertise to use. In fact, licences forbade any modifications to sets. Licences? We nearly forgot those. One of the components of a legal CB system was that every set required a paid licence issued by the Department of Communications (and Transport). They were very easy to get: you simply applied for them and paid your money and you received your licence (and callsign). But guess what? The number of licences issued was a small fraction of the number of sets sold. Woops! Something must be wrong with the accounting system. . . And as far as callsigns were concerned, the use of official (government issued) callsigns was, well, more in the breach than the observance. It didn’t take a rocket scientist to work out what was “wrong”. For years, thousands upon thousands of (illegal) CBers had operated without licences and with their own self-issued callsigns. So why change just because the Government said so? Several methods were tried to get users licenced, including making the licence a conditon of sale. But it was all in vain. Eventually, the powers that be in Australia relented and the US model was followed – as long as the set used was approved, no licence was required. UHF CB repeaters were also allowed, which significantly increased the range of sets. And because UHF CB uses FM, reception was much clearer than on the old AM/SSB (27MHz) system. Apart from the fact that AM is prone to interference anyway, the main reason CBers started using 27MHz was that very few other users wanted it. It’s regarded as the “garbage” band, with lots of naturally occuring (and some man-made) noise. A lot of industrial, scientific and medical equipment is in the 27MHz band. 2000 rule changes We included this shot of one of the Dick Smith Electronics “digitor” sets mainly to show the right way to talk into a walkie talkie: across it, rather than into it. Most people talk directly into a radio which results in distortion. Use ’em like a mobile. 8  Silicon Chip Quite recently, the Australian Government announced some new rules associated with UHF CB which to some extent legitimises what has been happening for some time. They allowed the use of CTCSS – so-called “Tone Squelch” – which had been available on many transceivers but which was not allowed to be used. Perhaps more importantly, they allowed two channels – 22 and 23 – to be used for data transmission; more specifically for telemetry and telec-ontrol. At the same time, they prohibited speech on these channels. This is quite a change from the Government’s previous position on CB, which was purely as a short-range voice medium. But as we said, it only recognises what has been fairly common practice in the past anyway. That’s not dissimilar to pretty well all of the “advances” in CB radio since its inception! And that’s where today’s personal radio history lesson concludes. But wait a minute – there’s another type: the LIPD mentioned before. These 69-channel microprocessor-controlled 433MHz LIPD handhelds from Jaycar Electronics (shown here about life size) certainly attracted our attention – and that of a number of people who saw them during our tests: “Ooooh! Aren’t they cute...” But it was their performance and features which really made them stand out. We were sorely tempted to go for these little pocket powerhouses! LIPD LIPD stands for low interference potential device and is a term given to a whole raft of radio equipment – not limited to (but definitely including) two-way radios. We’ll limit our discussion to twoway radios. There are many frequency bands available to LIPDs but the equipment we’re interested in uses the 433/434MHz UHF band. As the LIPD name suggests, these radios are low-power devices (much less than CB radios) and, theoretically at least, don’t have enough power to interfere with other services using the same bands. Unfortunately, this has not quite proved to be the case and some LIPD radios have caused great angst amongst the amateur radio fraternity. The problem is that many of the LIPD radios are fitted with channels which happen to be the same frequency as the input to amateur repeaters (which also share the 430MHz band). Amateurs also maintain that these attractively priced radios are being used – quite legitimately – by users whose safety could be compromised by the fact that (also quite legitimate) much higher power amateur transmissions could easily break through. They cite cases such as crane drivers and dogmen communicating with each other and ask who would be responsible if an amateur conversing with another amateur said something like “drop down now” and the crane driver mistook that as the dogman’s command… As you can see, there is room for concern. Despite this, however, we will look at the use of LIPD transceivers in our quest for the perfect unit. Our requirements We said before that the transceivers were to be used in sport. To be more specific, we wanted them for use at Surf Life Saving Carnivals for communication between the carnival referee, the various area referees, the first aid people, the announcers, the carnival organisers and, very importantly, the inshore rescue boats (“rubber ducks”) on water safety duty. The range we needed was not particularly great – about 1km or so would be the most needed for all but the very largest carnivals. We imagine that most other sporting applications would find this range more than adequate. However, we needed reliability – it is imperative that the radios operate when needed, particularly where safety is concerned. Other considerations were: battery life and cost; the availability of accessories such as headsets or earpieces and microphones; durability and service backup. Some radios scored well in some of these areas, some not at all. To get a good sample from which to select, we chose models right across the price range. The cheapest radios were, basically, toys (in fact they came from the toy department at Coles!) and sold for $20 pair. The dearest was a fully waterproof UHF CB handheld which sold for $356 each. Here’s how each stacked up: MARCH 2001  9 (A) HF (27MHz) Single Channel AM “Walkie Talkies” Coles Supermarket, $20 pair. The performance of these sets certainly reflected the price. You pay peanuts, etc. They operate on 27.145MHz ( HF CB channel 14) and as such, could well experience interference from other CBs even some distance away on this popular frequency. There is no volume control and no squelch (so you constantly receive a rather annoying and intrusive – and loud – background noise). The only “control ” as such is the push-to-talk button. There isn’t even an on/off control: the transceiver is turned on by releasing the pop-up antenna and turned off by retracting it. There is a telephone-type keypad on the front of the sets but it is purely decorative (despite the beeps each key makes!). A major disadvantage (at least as far as we were concerned) is the power source: a 9V battery. If you’re only buying these occasionally that mightn’t be such a problem but with 9V alkaline cells now retailing for five dollars (plus), buying batteries for, say, 20 transceivers is a significant bite out of the budget. Rechargeable 9V batteries could be an option but the initial expense is high. Transmission range was claimed to be “up to 100m line of sight”: we were flat out getting them to work well over this distance. Hey, you can yell that far! Our Verdict: Yeh, well, er... (C) VHF (55MHz) Single Channel FM “digitor” brand, $69.95 each, Dick Smith Electronics This type of transceiver is quite an attractive package with some advantages for our application, albeit with a couple of disadvantages. First “plus” is the frequency – 55MHz: this is well above the “CB” bands and is not therefore subject to significant interference. Only if transceivers operating on the same frequency are used in close proximity could you expect interference. Another is the fact that optional headset/microphones are available for hands-free operation. There are several channels available for 55MHz transceivers but many hand-helds have only one fitted. If you look around you can find 2-channel sets and some we have seen have up to six channels fitted, selected by a knob. We have had a fair amount of experience with 55MHz sets – in fact, we have used “Realistic” brand sets (from Tandy Electronics) for some years. The major cause for concern we have had with them was range: up to about 200m or so they have been fine but they suffer sudden dropout in the 200-300m range. And as we needed up to 1000m or so, this was a problem! The “digitor” brand sets we looked at for this review were quite different to what we had used – for a start, these had flexible rubber antennas instead of the mini-telescopic type we were used to. That’s a big plus (see above). While there is no squelch control, they had automatic squelch (no annoying noise!). There is a mic sensitivity control which is used in conjunction with an optional mic/earpiece for VOX (ie, hands- free) operation. Incidentally, we have also used Realistic headset transceivers (on the same frequency as the hand-helds) for many years but our experience with these has not been good. The head bands themselves are not robust enough and are easily snapped, while the wire antennas do not allow a broad-brimmed hat to be worn – a definite no-no on the beach! We asked Tandy about replacement head bands only to find the cost is much the same as replacing the whole unit! One point of warning for any organisation planning on using any set with VOX capabilities. Most (non-technical) people do not have a clue what “VOX” means (voice operated transmission, by the way!) and you will experience a lot of unintended conversations until every set is switched back to PTT (push-to-talk) operation. This, even when you hand out the sets already turned on and switched to PTT: people can’t resist fiddling with switches! Claimed range is up to 300m – as already stated, we’ve found this to be a little on the optimistic side. Our Verdict: could be a contender in many applications. But not ours! 10  Silicon Chip (B) HF (27MHz) Single Channel FM “digitor brand”, $69.58 each, Dick Smith Electronics The frequency of operation is the same as the above but these use the FM (frequency modulation) mode of transmission which is supposed to result in clearer transmission. Whether they achieve this or not is quite subjective – like the cheaper variety above there is no squelch control so they constantly receive background noise. On the positive side, FM is subject to less interference from atmospherics so perhaps the noise won’t be quite so intrusive. One major disadvantage of this particular transceiver is the long (1m) telescopic whip antenna. While having a long antenna will theoretically achieve better range than a helical ( rubber) antenna, experience has taught us that these whips will very quickly be damaged – broken or bent. Like the first transceiver, this one is powered by a 9V battery and the same comments apply about cost of operation. Range is claimed to be “up to 200m” which was inadequate for our purposes. We were, though, able to verify that they worked up to this distance. Our Verdict: they'd be good for kids if it wasn’t for that whip. (D) UHF LIPD (433MHz; 69 channels). “Tek City” brand, $99 each, Jaycar Electronics Now here is one of the most amazing little radios we have ever come across. When we say little, we mean it: just 30mm thick, 65mm wide and 110mm high (or 150mm if you include the flexible antenna). That really is shirt pocket size. With 69 channels to choose from you’re sure to find a channel or fifty that is not in use. But there’s a lot more to it than that. These microprocessor-controlled transceivers have an amazing array of features. While offering “normal” two-way communication between other sets on the same channel, it has a variety of calling and listening modes which can call or listen to specific sets or groups of sets – including conference calls. You can select from any of 10 sub-tones which allow access to other sets having the same sub-tone and channel set (other sets with different or no subtones, even if on the same channel, are ignored). There’s even a built-in clock, stopwatch, alarm clock and settable auto power-off timer. Ten memories allow the saving of popular channel/subtone/etc settings for instant recall. And there is even a selection of transmittable melodies so that other users will know that you is you! All controls on the Tek City two-way radio are push buttons – and apart from the usual push-to-talk button it’s not particularly intuitive so until you get to learn the controls, the manual is a must. The case is said to be splashproof but we’d rather not put that to the test. With just 25mW output you might expect range to be very low but we found this not to be the case. Over 1km line-of-sight was no problem at all. 25mW output though has a big benefit when it comes to power consumption. 40 hours of continuous operation is claimed from the 4 x “AAA” batteries though no duty cycle (transmit/receive) is given. One point: AAA batteries are usually significantly dearer than AA cells. Bearing in mind our earlier comments regarding amateur repeater inputs, we would suggest steering clear of channels which coincide with amateur repeaters in your area (ask your local WIA office or radio club and they’ll advise you). But with 69 channels available, there still should be plenty which you can use. Incidentally, Dick Smith Electronics also plan to sell a 433MHz LIPD set (it was shown in last year’s catalog). So far, though, they haven’t reached the market because DSE are having special models manufactured which will not interfere with amateur operators or vice versa. Our Verdict: one of the most innovative hand-helds we’ve seen. Definitely on the short list. MARCH 2001  11 (E) Pocket-size UHF CB (476/7MHz); 40 channels Uniden UH-040XR, $99.00 each from Dick Smith Electronics These low power UHF CB sets were extensively advertised prior to last Christmas. We must admit that if we were impressed with the LIPD sets, we were also very taken with these. They’re also obviously microprocessor controlled and while they don’t offer as many features as the 433MHz sets they’re actually slightly smaller. They’re a tad higher (115mm) thanks to the volume control/on-off switch on top of the set and the integral, non-flexible antenna is higher (180mm). But they’re slightly thinner (27mm) and the taper-shaped case is 60mm at its maximum (makes it easier to fit in the pocket). All 40 UHF CB channels can be scanned or you can preset as many of those 40 channels to scan as you wish. It also has priority channel scanning where it monitors one preset channel every 1.5 seconds. Power output is limited to just 50mW. This equates to 150mA current drain from the 3 x “AA” batteries. One nice feature of this radio is its ability to switch to a “sleep mode” when the batteries are low. You cannot scan or transmit but receive is still available. The radio is cable of repeater operation (duplex mode) but for our purposes, this was not required. Squelch threshold is preset at 19mV but can be over-ridden in case of very weak signals. Uniden claim a range of up to 3km over flat open terrain. We were able to confirm this distance along the beach – in fact, we achieved 4km across water. Our Verdict: A great little performer at a very attractive price. (F) Splashproof UHF CB 476/7MHz, 40 channels. Uniden UH-052XR, $399.00 from Dick Smith Electronics This could be regarded as the “big brother” to the above UHF CB. It is bigger – significantly bigger – at 60 x 50 x 165mm (275mm including flexible antenna). At $399, it’s also a lot more expensive. For the extra money, you get a much more powerful transmitter (5W – maximum legal power, switchable down to 1W). It also has a rechargeable battery (7.2V 900mAh NiCd) so at least you won’t be forever forking out coin of the realm to keep talking. (And at 5W output, you’d need lots of coins because the drain is 1500mA!). The radio is described as splashproof – exactly what this means is not too clear to us (it complies to US Military standard 810E Method 506.3, Rain II – so now you know too!). Uniden claim it will withstand splashes of water but not immersion. Unlike the UHF CB above, the flexible rubber antenna is removable to allow connection of an external (eg mobile) antenna if you wish. The UH-025XR has a wide range of user features including CTCSS (continuous tone coded squelch system), complete or programmable scanning, priority channel, power saving, busy lock-out channel and more. Unlike the other set, the squelch control on this unit is settable but it also has a monitor push-button for instant squelch override. Optional accessories include a VOX headset, speaker microphone, cigarette lighter charger and battery eliminator. As would be expected from a 5W system, the range of this handheld is very much greater than the 0.5W model. We gave up after a couple of kilometres of beach walking – we cheated and sent the other unit off in a car. It gave up the ghost after the car went around a large hill 4km away (it’s hard to find flat areas to check line of sight on Sydney’s northern beaches!). Bearing in mind our earlier comments about interference from other UHF CB users, this long range could actually be a hindrance in our application. Our Verdict: If we wanted maximum range, this would be the one we’d go for. 12  Silicon Chip (G) Waterproof UHF CB (476/7MHz, 40 channels) Uniden UH054A Aquamax. $356.00 from Dick Smith Electronics Here’s one that really attracted our interest with our beachside application: a waterproof radio! Despite everyone’s best intentions, accidents do happen and we have had a number of handhelds take an unwanted swim over the years. Well, a small swim wouldn’t worry this radio one bit. It’s rated to 30cm for half an hour – admittedly, not a great depth but the usual “oopses” we experience (eg, someone running along the water’s edge and the radio bouncing out of a pocket!) would be consistent with this depth. (Let’s face it – if you drop it overboard from a boat it’s going to go straight down anyway so your chances of recovery aren’t high). Otherwise this radio is not dissimilar from the other sets we looked at. Size is about half way between the other two at 32 x 62x 160mm or 245mm if you include the antenna. Controls are all push-button type (they have to be to achieve “waterproof-ness)” and are similar in operation to the other sets. One nice touch, and one which we would find useful, is its dual-channel watch capacity – you can listen to one channel while monitoring another. Power output is 0.5W and this set also has a NiCd battery supplied, sealed in by a gasket. Unlike the above model, it is supplied with a “drop in” charging cradle which doubles as a desk stand. The range of this set was more than adequate for our needs. With a smaller antenna and a lower output power we expected a smaller operating range and this proved correct in out tests. We needed a kilometre; these easily achieved the claimed three kilometres. The biggest disadvantage (as far as we were concerned) was the price of these radios: $356 each would be really stretching the friendship! Our Verdict: If only we could afford such luxury as a waterproof radio... So which one did we choose? It was a real toss-up in the end. We were very impressed with the Tek City unit from Jaycar and the tiny Uniden UH-040XR. Both were the same price, both had more than adequate range, both would do the job perfectly. Our final decision was made not by performance – there wasn’t much between them – but on the grounds of ongoing battery costs. For reliability and safety, we tend to replace batteries after each surf carnival so we figured eighty “AAA” cells each time (we use 20 radios for a carnival) would cost a lot more than sixty “AA” cells, especially with the bulk prices now available on alkaline AA cells. You might be wondering about fitting these sets with rechargeable cells. We wondered the same thing but this would have added a big chunk to the cost. More importantly, our experience with NiCd (or NiMH) cells in a marine environment has not been good. They seem to corrode very quickly and while this isn’t a problem if the battery is a throw-away alkaline, it is a problem with a (relatively expensive) rechargeable. Scratch that idea. If money was no object (huh!!!) we would have gone with the Uniden UH054. The obvious reason for this would be the ruggedness and waterproof characteristics of this set; the supplied sealed rechargeable battery a bonus in ongoing cost savings. But at more than three times the price we simply couldn’t stretch the budget that far. We’ll probably buy a couple of them for use in our water safety “rubber ducks” but that will be about it. Our thanks to Jaycar Electronics and Dick Smith Electronics for assisting with this survey. References: Australian Communications Authority – www.aca.gov.au Jaycar Electronics – www.jaycar.com.au Dick Smith Electronics – www.dse.com.au MARCH 2001  13 By GREG SWAIN Mobile Magic Using a PC to Drive Your Mobile Phone Looking for an easy way to send text messages from your mobile phone? Or how about a fast and easy way to update phone­book entries? A PC or laptop computer is the answer and the right software can also turn your mobile phone into a wireless modem for sending and receiving email. 14  Silicon Chip The Nokia Data Suite comes with a cable that connects your phone to the serial port of a PC. It’s the same story when you want to store numbers in your mobile’s phonebook. Once again you have to cycle through the various letters to enter a person’s name and this can take quite some time if you’ve just upgraded your phone and have a new SIM card and a long list of numbers. So what’s all this leading to? Elementary, my Dear Watson – you can use your PC (or a laptop) to control your mobile phone. Depending on the mobile phone, this not only makes it easy to send SMS messages and edit your phonebook (or contacts) but allows you to do lots of other fancy things as well. Taking control S IT DOWN TO WRITE something about mobile phones and you open the proverbial can of worms. These things (mobile phones not worms) come with a bewildering array of features that can take some getting used to, especially if (like me) you’re over 20 years old. One of the most popular features is the “Short Message Service” (or SMS), which is used for sending short text messages from one mobile phone to another (for the cost of a local call). What, you didn’t even know that your mobile phone could do that? Don’t feel bad – hell, my brother didn’t even know about the “Snakes” game on his Nokia 5110 mobile until given a demonstra­tion by his 5-year old son! If you don’t know about SMS, ask any teenager – they’re busily punching out messages to each other on their mobiles every day and racking up big bills in the process. It must be a gold­ mine for the telco companies. For those who don’t know any teenagers, we’ll briefly ex­plain how SMS works. It’s a very simple concept – all you have to do is scroll to the “Write messages” (or similar) area of your phone and punch in a short message using the buttons on the keypad. Then, when you select “send”, you are prompted for the destination number (ie, the mobile number that you want the message sent to). When you enter this, the SMS message is sent to the desti­nation phone via the “message centre” of your mobile carrier. If the destination phone cannot be contacted, the SMS message is stored at the message centre and immediately forwarded when the phone reappears on the network. The big advantage of this scheme is that the destination phone doesn’t have to be switched on when you send an SMS mes­sage. Instead, the message goes via the carrier’s message centre and the number for this is usually programmed into your SIM card when you buy the phone. If it isn’t, it’s simply a matter of obtaining the number and entering it yourself. As well as the PC, you also need software to suit your particular phone – assuming that it’s available. Oh yes; one more thing – your phone must either have an infrared (IR) port or a socket to accept a data cable. There’s no point trying to cover every conceivable brand and model of phone here – life’s too short for that. You can check out the details for your particular phone in the manual and on the manufacturer’s website. In our case, we played around with the popular Nokia 5110 and 6110 models ‘cos that’s what everyone in the office has – apart from the office techno-freak with his Nokia It’s clumsy but ... SMS messages are entered by cycling through the six upper case and lower case letters associated with each button on the telephone keypad. This can be a tedious process, particularly if the message you want to send is more than about 10 or 15 charac­ters (SMS messages can be up to 160 characters long). This Nokia 6110 mobile phone features both a data connector and an infrared port. MARCH 2001  15 Fig.1: adding new contacts, editing existing contacts and sending messages from your mobile phone are a breeze with Nokia’s Data Suite. You can even import address books from other applications, such as Outlook Express or Excel. 8210 (he always has to have the latest). There’s lots of software that lets you “do things” to these phones but let’s start by looking at Nokia’s own Data Suite 3.0 package which runs under Windows 95, 98 and NT. Nokia Data Suite There are just three items in this package: a manual, a CD-ROM and a data cable that connects your phone to a spare serial port on the PC. Naturally, you have to buy the correct package to suit your phone, as the data connectors vary. Our review package included a DAU-9P cable which works with Nokia 5110, 6110, 6150 and other compatible Nokia phones. The main program itself features a vertical toolbar that offers six main functions: Contacts, Messages, Calendar, Dialler, Profiles and Settings (see Fig.1). You don’t really have to learn how to use this stuff because it’s all fairly self-explanatory. Click the Contact button, for example, and up comes the list of contact numbers that you’ve programmed into your phone. Using the PC, you can easily edit these contacts, add new contacts and even import .csv (comma separated value) text files exported from other applications such as Microsoft Outlook and Outlook Express. The mobile’s memory is updated in real 16  Silicon Chip time and it’s certainly a lot faster than trying to add contacts or edit existing contacts using the keypad. Right-clicking on a contact brings up a drop-down menu with a list of options. Among other things you can choose to call the contact, send an SMS message or assign the contact to one of several Caller Groups (Friends, Family, VIP, Colleagues, Other), so that a distinctive “dinky” little graphic flashes on your mobile’s screen each Fig.2: the Nokia Data Suite Message Editor window. Typing a message on a PC is much easier than entering it on a telephone keypad. time you receive a call. You can also choose a distinctive ring tone for each Caller Group. Of course, all these features can be programmed in via the phone keypad anyway – it’s just far easier to do it using the Nokia software. Note also that Caller Groups are only featured on some phones, such as the Nokia 6110 and 8210 models. They’re not featured on the popular Nokia 5110. Sending an SMS test message is an absolute snack. You just bring up the Message Editor, enter your message and choose the recipient from the list of contacts (or type in a phone number yourself). You can then either immediately send the message to the destination mobile or save it to the Drafts folder. Incoming messages are stored in the Inbox folder and are viewed by click­ing on them (Fig.3). The Calendar and Dialler functions are self-explanatory, while the Profiles button lets you tailor individual Caller Group ringing profiles and load different icons. The program also makes it a simple matter to set up call diverts and tweak other settings. Finally, the Nokia Data Suite package includes four other utilities: Nokia Database Converter, Nokia PC Composer, Nokia PC Graphics and Nokia PC Restore. Among other things, these utilities allow you to back up (and restore) your phone’s settings and to compose your own ring tones and onscreen graphics, provided your phone supports these features. What about infrared? As well as the data connector, some Nokia phones (eg, the 6110) also include infrared capability while others have infrared capability only. There’s a catch here, though – the Nokia Data Suite for the 5110 and 6100-series phones will only work via infrared if your PC is running Windows 95. It won’t work with Windows 98, Windows Me or Windows 2000. That’s because Windows 98/Me and Windows 2000 configure their IR ports in a different manner to Windows 95 and Nokia hasn’t modified its software to suit. The problem is, how many people are still using Win95? In addition, many of Nokia’s earli­er phones (including the 6100 series) are not IrDA compliant and work in DirectIR mode only. OK, so that’s Nokia’s official line but that’s not the end of the story. Fig.4 (below): Nokia PC Restore lets you backup and restore your phone’s settings – handy if you’re duplicating or changing phones. Fig.3: clicking the Messages button lets you view incoming SMS text messages directly on the PC’s monitor. Incoming and outgoing messages are stored in folders, just like in an email program. There are a lot of smart cookies in this world of ours and it doesn’t take long for someone to find a way around this kind of problem. Take a look at the accompanying panel if you want more information on this subject. Handset Manager Nokia’s Data Suite might not work over an infrared connec­tion for Windows 98/Me (at least not officially) but here’s third party software that will. It’s called “Handset Manager” and it works with a range of phones, including the Nokia 6100 series; Nokia 7110, 8210 & 8850; Siemens S25, S2588, S35i & S3568i; Ericsson R320; and Motorola L series. Handset Manager is supplied with its own infrared adapter which plugs into the serial port of a PC – it won’t work with any other infrared adapter or the built-in IR port of a laptop. The software comes on a CD-ROM and you simply select your model phone during the install procedure. As with Nokia’s Data Suite, Hand- Using Your Mobile Phone As A Modem To Access Email Or Send Faxes The latest mobile phones really pack a lot into one package and many include an inbuilt GSM modem. If you have a Nokia 5110/6110 or similar, the setup procedure for the Data Suite automatically installs modem drivers and a virtual COM port for the phone (Fig.5). This is a great feature because you don’t have to purchase a separate GSM card to get connected. By combining your mobile with a laptop computer, you can dial in from anywhere and send and retrieve email, faxes and other data – just as you would from an ordinary desktop PC with a conventional modem. You can also browse the web if you really have to but the modem only runs at 9600 baud (up to 14,400 for faxes), so it’s slow and not really a practical proposition. By the way, the Nokia Data Suite requires two ports – the physical COM port to which the phone is connected (usually COM1 or COM2) and a virtual port (usually COM3) for the Nokia modem. Note that you have to configure your dial-up and communications software to use the virtual COM port. In some cases, you don’t really need the Nokia Data Suite if all you are after is a modem driver. Free drivers for some high-end Nokia phones are available for download from www.forum.nokia.com (eg, for the 6210 & 8210 but not for the 5110 and 6110). Fig.5: the Data Suite automatically installs modem drivers and assigns a virtual COM port for your phone, so that it can function as a mobile modem. MARCH 2001  17 Fig.6: Handset Manager also offers easy phone book editing and SMS messaging, as well as a host of other features. set Manager lets you edit and backup your phonebook, send SMS messages, edit and download personal logos and ring tones to the phone, and edit the calendar. No modem drivers are included, though. The version we looked at supported Windows 95/98 and Wind­ows 2000 but the manufacturer’s website now includes an update for Windows Me. There are also software updates to support the Nokia 6210 and 8250 models – see www.mobileaction.com.tw Web messaging Now here’s something that you probably didn’t know – you don’t need a mobile phone to send an SMS message to another mobile. Instead, you can do it directly using a PC and your service provider’s website. Telstra MobileNet’s web SMS service is called “WebNotes” but before you can use it, you have to join telstra.com to get a username and password (you do this by going to www.telstra.com and following the links). Once you’ve done that, you then use their website to register to use WebNotes. The idea here is to submit your phone number and the system then automatically rings your mobile with a PIN number which you enter into the appropriate field and re-submit. This is done to confirm that you are who Looking for a new-generation WAP (Wireless Application Protocol) phone. The Motorola Model V2288 even comes with an inbuilt FM tuner. (Dick Smith Electronics). you say you are, since WebNotes SMS messages are charged to your mobile account at local call rates. That’s all fine in theory. Unfortunately, I just couldn’t get it to work because Telstra’s site kept throwing “wizard has expired” messages at me when ever I tried to do anything. Eventu­ally, after repeated attempts, I did manage to obtain a user name and password and even managed on a couple of occasions to submit my phone number and obtain a PIN. However, each time I tried to submit the PIN, it ran off the rails again. Another SILICON CHIP staff member encountered similar problems but you might have better luck. Give it a try. Optus offers a similar web mess­ aging service called WebSMS. Free software Handset Manager is designed for use with IR-capable phones and comes with its own infrared adapter (the MA-600). It supports Nokia, Motorola, Ericsson and Siemens mobile phones and works with Windows 95/98/Me and Windows 2000. 18  Silicon Chip Try this – go to a popular search engine (eg, www.yahoo.com), type in “Nokia AND freeware AND share­ ware”, and check the result. That’s right – there’s lots of software for Nokia mobile phones floating around “out there”, the vast majori­ty of it for Nokia Data Suite Win98/Me Infrared Workaround Depending on your phone, the Nokia Data Suite can be used over an infrared link but only if your system is running Windows 95. There are a couple of reasons for this. First, Windows 95 is the only version that supports both DirectIR (as used on the 6100-series phones) and IrDA without changing the drivers. Sec­ ond, it stores the infrared device under “Ports” in Device Manager and describes it as a “Generic IR Serial Port (COMx)” – see Fig.7. By contrast, Windows 98 and later support IrDA, store the infrared device under “Network adapters” and create two virtual COM ports (Fig.8). This isn’t compatible with the Nokia Data Suite but it doesn’t take long for someone to solve this sort of problem and post it on the web (although it won’t work in all cases). Basically, the workaround involves hacking the msports.inf file which is found in the c:\windows\inf folder and then rein­stalling the infrared device. This “tricks” the system into installing a “Generic IR Serial Port” under Ports, just like Win95 does. Once this has been done, you install the Nokia Data Suite in the usual manner, ignoring its complaint that “Setup did not find a phone!” (that’s because there’s no cable). You then make a couple of simple changes to the registry and that’s it – the Nokia Data Suite will now work over an infrared link. If you want the details, take a look at www.nokiainfo.f2s.com but be warned – back up the registry and the msports.inf file before making any editing logos and/or ring tones. There are even programs that let you convert MIDI music files to ring tones. One popular shareware program is “LogoManager” but the name sells it well short. As well as creating logos, it can also be used for SMS messaging and for backing up and editing your phone­book. You can download a trial version from www.logomanager.co.uk LogoManager can work with either a data cable or via in­frared, so if you have an IR-capable phone you can save the cost of a data cable. IrDA-com- Fig.7: Windows 95 stores an IR device under “Ports” in Device Manager and describes it as a “Generic IR Serial Port”. Fig.8: Windows 98 and later store the IR device under “Network adapters” and create two virtual infrared ports (COM & LPT). changes so that you can recover from any little accidents. Be warned also that we haven’t tested the technique described and the risks of hacking your computer are all yours. By the way, you have to do the same thing for LogoManager if your phone doesn’t support IrDA but supports DirectIR. There are different workarounds described for Windows 98SE, Windows Me and Windows 2000 and you can even download a modified msports.inf file if you don’t feel confident about hacking yours. The same goes for the registry hack – just download the relevant registry update file for your version of the Nokia Data Suite and double-click it to make the change. Finally, note that Handset Manager also only supports Di­rectIR although you don’t have to go through the same hassle to get it working since it comes with its own drivers. There’s just one thing to watch out for here – if your phone supports both IrDA and DirectIR (eg, Nokia 8210), you have to make sure it is operating in DirectIR mode. How do you do that? Simple – just activate the infrared link by scrolling to the “Snake 2-Player” mode (menu 6-2-3). Yes, that’s right – the good ol’ snake game uses DirectIR for its 2-player link. Don’t use menu 9 on the Nokia 8210 (or similar) because that will activate IrDA. There are no such problems with the Nokia 6100 series since they support DirectIR only. On these phones, you can just scroll to the infrared function (menu 9) in the usual manner. patible phones should work without any problems but you’ll have to jump through the same hoops as for the Nokia Data Suite to get a Nokia 6100 (or any other mobile with Direct­IR) Product Availability Nokia Data Suite: Dick Smith Electronics. Handset Manager (includes IR Adapter): Dick Smith Electronics; MicroGram Computers. working over an infrared link. By the way, while you’re on the LogoManager website, be sure to visit some of the suggested links. In particular, you should visit the “GSM Topsitz” page. There are literally hundred of sites offering Nokia ring tones and logos for use with Logo­Manager. The future The future is yet another acronym, this time called WAP – Wireless Application Protocol. WAP phones are continued on page 21 MARCH 2001  19  Using infrared devices with your PC You don’t have to jump through any special hoops to install an infrared device on your PC. It’s really just a matter of attaching the device and installing the drivers. Talk about infrared communications is fine but how do you actually install an infrared link so that you can comm­uni­cate with the growing range of IR-enabled gadgets? If your motherboard has an IR data connector (and most do), you’re already half-way there. All you have to do is plug an IR link device into it, enable IR support in your system BIOS and then install the drivers when the new device is detected during the boot procedure. If you’re running Windows 95, this will install a “Generic IR Serial Port” in the Ports section of Device Manager. This supports both the DirectIR and IrDA standards. When you reboot the system, you will see an “Infrared Monitor” icon in the System Tray (bottom, right of Taskbar) and, by double-clicking this, you can set up various options as shown in Figs.1-3. Later Windows versions (Windows 98/98SE Windows Me and Windows 2000) operate differently when it comes to infrared. On these systems, the infrared port is stored under “Network adapt­ers” and virtual infrared COM and LPT ports are stored under the Ports section. These systems support the IrDA mode only (unless hacked – see page 19). And that’s really all there is to it. As soon as you bring an IR-enabled gadget (eg, a mouse or a mobile phone) close to the IR link, the two will automatically start communicating. A suitable device is the Actisys ACTIR 210L which runs at the standard infrared (SIR) speed of 115.2Kb/s. It comes in two parts: (1) a backplane connector with a socket and data cable that plugs into the PC’s motherboard; and (2) an infrared trans­mitting device (this plugs into the socket on the backplane connector). There’s also a driver disk for Windows 95 users but this isn’t required for Windows 98/Me or Windows 2000. The end of the data cable that plugs into the motherboard has a standard 5-pin connector (one pin is unused) and the wiring standard should suit the vast majority of motherboards. Note that one of the pins is unused. If your motherboard supports fast infrared (FIR), then you might like to consider the IRwave IR320F Serial Infrared Adapter. This device runs at 4Mb/s and also plugs into your PC’s mother­board. Be sure to enable FIR support in your system BIOS to run this device. What if your motherboard doesn’t have IR support? In that case, you can use the IRwave IR320S which plugs directly into a spare 9-pin COM port. This device runs at 115kb/s (SIR) and operates under Windows 98, Windows Fig.1: double-clicking the IR icon in the System Tray brings up this box, which shows the available IR devices. Fig.2: the Options tab lets you enable/ disable IR communications and install software for Plug & Play IR devices. Fig.3: the Preferences dialog lets you choose to play sounds each time an IR device comes within range. By GREG SWAIN 20  Silicon Chip Suitable hardware The Actisys ACT-IR 210L runs at the standard infrared (SIR) speed of 115.2Kb/s and comes in two parts: (1) a backplane connector with a socket and data cable that plugs into the PC’s motherboard; and (2) the infrared trans­mitting device itself. Fig.4: the IR icon as it appears in the System Tray. Me and Windows 2000. Finally, there’s the USB-IrDA which attaches to any USB port and supports both SIR and FIR data transfer rates. A driver disk, cable and manual are included in the package. All four IR devices are available from MicroGram Computers. The Actisys ACT-IR210L (Cat.8518) costs $89; the IRwave IR320F (Cat. 8941) $89; the IRwave IR320S (Cat. 8421) $99; and the USB-IrDA (Cat. 8923) $139. You can contact MicroGram Computers at (02) 4389 8444 or browse their website at www.mgram.com.au for more SC information. The IRwave IR320F and IR320S infrared adapters are visually identical. One plugs into your PC’s motherboard, while the other connects to a spare serial (COM) port. Mobile Magic – from p19 The USB-IrDA adapter attaches to any USB port and supports both standard (SIR) and fast (FIR) infrared data transfer rates (ie, from 115Kb/s to 4Mb/s). Fig.9: Nokia PC Graphics comes with a selection of standard graphics and even lets you compose your own graphics. This one is for someone you don’t want to talk to! already here and support mobile Internet services such as email, ticket booking, banking, news and weather. And they support high-speed (if that’s the term) Internet connections, with email downloads up to 43.2kb/s. But that’s a whole new story. In the meantime, there’s lots you can do with your existing GSM phone. Why should the teenagers have all the fun? Check these websites www.forum.nokia.com – for modem drivers, updates and free software downloads. www.nokiainfo.f2s.com – for the good oil on infrared. www.frenetic.com.au – a source for Nokia data cables. www.telstra.com – for WebNotes (send SMS messages a mobile phone). www.logomanager.co.uk – for a trial version of LogoManager and lots of links to other related sites. www.optus.com.au – for WebSMS. www.blueskyfrog.com.au – for something different. SC MARCH 2001  21 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au Hifi Review Marantz DR 6000 Compact Disc Recorder Most people know that computers can incorporate a CD Writer and that you can use them to dub recordings onto CD ROMs. But you don’t need a computer to make your own CDs and you don’t need to be computer literate at all. Instead, you can use the Marantz CD Recorder to do the job and all without touching a mouse or a keyboard. These days there is no doubt that CDs are the preferred recording medium, having well and truly superseded vinyl LPs, reel-to-reel tapes and cassettes. But many people still have large collections of LPs and tapes and would like to dub them to the more convenient CDs. However, for many people this is not an easy hurdle to overcome, even though they may already have a computer. In fact, if you want the full lowdown on dubbing to CDs using a computer, 26  Silicon Chip you need to refer to the January 2001 issue of SILICON CHIP. This very comprehensive article outlined the tech­ niques, the software and the hardware you need to be able to do this job. But it must be said that there is a considerable in­vestment in computer hardware and software and the inevitable learning curve in properly mastering this equipment. Nor can you use just any computer – you need a reasonably recent Pent­ium model with a large capacity hard disk. For many people then, a freestanding CD Recorder which requires no com­ puter at all would be a great advantage. The Marantz DR 6000 is that machine. We should point out that, as with any freestanding CD Recorder, the DR 6000 need not stand idle when it is not being used for recording; it also doubles as a high quality fully featured CD player. This means that if you were considering acquiring a new CD player anyhow, you can now have both a CD player and recorder in the one machine. More importantly, the DR 6000 will record both Recordable (CD-R) and Rewritable (CD-RW) discs. While CD-RW discs are con­siderably more expensive than CD-R discs, they have the particu­lar advantage that they can be amended and added to at any time. Machine features Superficially, the Marantz DR 6000 looks pretty much like any other CD player. It has a disc drawer on the left hand side and an array of buttons Facing page: the Marantz DR 6000 CD Recorder will record on CD-R and CD-RW Digital Audio discs as well as double up as a high perfor­ mance CD player. on the front panel for Power, Open/ Close (the disc drawer), Rewind, Fast Forward, Stop, Play/Pause and two knobs, one for headphone level control and one labelled “Easy Jog”. The last-named control has only recently become a feature on CD players and allows you to quickly select a particular track without having to step through using the remote control or front panel buttons. The only clues to the recorder-nature of this machine are other buttons labelled Rec, Rec Type, Scroll and the five buttons under the display and these are labelled Source, Erase, Store Menu, Cancel/Delete and Finalize. However the labelling and styling of the machine is so understated that anyone casually using it for playing CDs could easily miss the evidence that it is a CD recorder. While we are on the subject of styling, we should comment on the subdued Marantz gold finish. This is a step back to the past in Marantz machines and is a very refreshing change from the uniform black (or charcoal) of other hifi equipment. Nor is the DR 6000 any more bulky than a typical CD player, being 440mm wide, 87mm high (including the bulky feet) and 317mm deep, including front panel knobs and rear connectors. Its weight is 4.6kg. On the rear panel, the DR 6000 has RCA sockets for analog stereo inputs and outputs (just like any cassette deck) plus a digital input and output and a remote input and output (for a system using the Marantz D-BUS remote control). It also has an optical input and output. Making direct copies of existing CDs is a cinch and in this case the DR 6000 can be used almost exactly like a cassette deck except that you can make a direct digital copy or an analog copy. In the digital copy mode, the DR 6000 automatically sets its sampling rate to match that of the source material (ie, CD, DAT or DCC). For example, the sampling rate for compact discs is 44.1kHz. There are restrictions on direct digital copies though, via the Serial Copy Management System (SCMS) incorporated in all CD Recorders. The SCMS places a code on any disc copy and this prevents it being copied again as a digital disc. However, there is no limit on analog copies. So provided you use analog signals from a CD player (or other analog source) there is no limit on the number of copies that can be made. Inevitably, such analog copies will not be quite as good as direct digital copies. The DR 6000 has a “CD-SYNC” feature which automatically detects track increments. Track increments cannot be added manu­ally, unless you interrupt the analog signal. In analog source material any silence or interruption of 2.7 seconds or more is interpreted as a new track – handy when you are recording off LPs too. Mind you, if you do want to record from LPs you need a turntable with an RIAA preamplifier or better still, the LP Doctor project described in the January & February 2001 issues of SILICON CHIP. Use digital audio CD-Rs There is another wrinkle that applies to all CD Recorders like the Marantz and while it is mentioned in the instruction manual it is pretty easy to ignore. Most CD-R and CD-RW discs cannot be used in an audio CD Recorder. That is because the manufacturers have not paid the necessary copy licence fee. You must use CD-R and CD-RW discs that are labelled “Compact Disc Digital Audio Recordable” and “Compact Disc Digital Audio ReWrit­able” respectively. When I set up to record I clean forgot about this limitation, loaded an ordinary CD-R which the machine pro­ ceeded to scan and then flashed up the message “Wrong Disc – Use Audio CD”. There was quite a bit of head scratching and then a call to the distributors to have the mistake pointed out. (Yeah – read the manual!). So provided you carefully READ the manual, recording of CD-R and CD-RW discs is pretty straightforward. Curiously, once you have made a recording, you can play it back on the Marantz CD Recorder but it won’t play on any normal CD player until the disc has been “finalized”. Among other things, this process puts a table of contents (TOC) on the disc that a normal CD player can read. However, The remote control for the DR 6000 can be used for track ti­tling. Each letter of the track title is individually selected and then entered. once a CD-R disc has been finalized, no more recording is possible. On a CD-RW disc though, you can add tracks or erase tracks from the end or erase the whole disc after it has been “unfina­lised”. This removes the table of contents from the CD-RW disc and transfers it into the memory of the DR 6000. By the way, you can add your own track labelling to the disc and this will come up on the display panel (if the player concerned can read it). Adding the text is a fairly laborious process, with each letter of the label selectable on the remote control. Overall, we were impressed with the Marantz DR 6000. Once you read the instruction manual, the recording process is quite straightforward and for many people, will be much easier than doing it via a computer and CD Writer. It is also a very good high performance CD player with a comprehensive list of features. For anyone considering the purchase of an equivalent CD player, the step up to the DR 6000 is not a big one. Even so, the Marantz DR 6000 is not a cheap machine at $1699. For more information, Marantz equipment is available from selected hifi dealers throughout Australia. You can also contact the Australian distributor, QualiFi, 24 Lionel Road, Mt Waverley, Vic 3149. Phone 1 800 242 426. SC (L.D.S.) MARCH 2001  27 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. Economy mic preamp has phantom power Electret microphones intended to drive balanced lines re­quire some means of power. Batteries work but are not desirable because they are an extra expense and they can go flat at incon­ venient times. The standard alternative method is to use “phan­ tom” power whereby a 48V DC rail feeds the electret capsule via the microphone’s balanced signal lines. Fig.1 shows the complete circuit but it may not be imme­diately obvious how the electret capsule is powered. The answer is that current flows from the +48V rail via the 10kΩ and the two 6.8kΩ resistors to each of the balanced signal rails. The current then flows back from the electret capsule via the common shield of Shaft rotation indicator This circuit is based on the front end of the Speed Alarm published in the November & December 1999 issues of SILICON CHIP. In that circuit the speed of the propeller shaft is sensed by coil L1 which consists of 500 turns of 0.2mm enamelled copper wire (ECW) on an 8mm (or simi­lar) bolt. Each time a magnet (or magnets) glued to the shaft passes the coil, 28  Silicon Chip the microphone cable. IC1, an LM833 low-noise op amp, is connected with balanced inputs and an unbalanced output and is set for a gain of 47. Extra gain will be required in most applications and this can be provided by additional op amp stages. The 48V supply to the electret a pulse is produced by comparator IC1. In this version of the circuit, the comparator drives the trigger input of IC2, a 555 timer connected as a one-shot. Each time the trigger input of IC2 is pulled low, the output at pin 3 goes high to drive LED1, for a time determined by the resistor and capacitor connected to pins 6 & 7. This circuit works well at high shaft speeds, during which LED1 will effectively be lit continuously. capsule is blocked from the op amp’s inputs by the series 47µF 50V electrolytic capacitors. These are followed by 15V transient absorbent devices but these could be replaced with a 15V zener diode and series silicon diode in each case. Marque Crozman, Sunnybank Hills, Qld. At low speeds though, say below 10 revolutions/second, the effectiveness of the circuit will depend on the magnet strength, the coil-tomagnet gap and the shaft diameter. Also a larger coil and larger bolt will provide more signal pickup. Increasing the magnet strength will significantly improve the sensitivity. Jaycar Electronics have some powerful magnets which would be suitable for this application (Cat. LM-1614). SILICON CHIP. UHF CB radio can now transmit data A fter having been lobbied for many years by rural users, the Australian Communications Authority (ACA) has announced changes to Citizens band (CB) radio licences to allow the transmission of data on UHF CB channels 22 & 23. The changes announced by the ACA regarding these two channels will allow for the use of selective calling techniques such as CTCSS (Continuous Tone Coded Squelch System) and telemetry and telecommand systems. Tone squelch allows a system of selective calling, where a number of transceivers share one channel but will only “wake up” and listen if they receive the same preset tones as they have had previously programmed. Telemetry and telecommand will allow data to be transmitted between sets. Previously the regulations for- The Uniden UH-100 is already equipped with CTCSS. Now it – and data transmission – will be legal. Courtesy Dick Smith Electronics. bade this, citing CB as a “voice only” medium. The use of these techniques will allow the design of cheap equipment to remotely monitor various parameters on farms including water levels in dams and rainfall in paddocks over a period. They could also be used to control irrigation pumps and even to open and close gates. Similar techniques could be used to remotely monitor equipment on boats, such as bilge water levels, battery voltages and even weather conditions - why go down to the boat if it is blowing a gale? Or maybe you might want to check the boat if it is blowing a gale! And how about security? Remote burglar alarms, remote control and monitoring and so on? The list of possible uses is endless. Which may be why some CB users are objecting to the changes. One change which has not been included is “packet radio”, currently allowed on the Amateur Radio bands. The ACA is also seeking to amend the UHF CB radio equipment standard to reflect the above changes. This will require the fitting of a “channel busy” light to indicate the presence of any signal on the channel concerned and a switch to disable any selective calling facility to create a “listen before transmit” function. Now that the change to allow data transmission has been made, channels 22 and 23 will no longer be available for voice transmission. If you want more information on the changes to the CB class licence and related topics go to: SC www.acma.gov.au MARCH 2001  29 Do you need a big digital clock that you can see from a lo-onggg way away? Then have a look at this PIC-based clock. It’s large, it’s bright, it’s very accurate and can be used in either 12 or 24-hour modes. It’s ideal for the home, in factories, offices, emergency services, armed forces, airports, satellite control centres ... By JOHN CLARKE This latest clock from SILICON CHIP is no ordinary clock. It is based on a PIC microcontroller to provide a number of unique features including the ability to adjust for very accurate timekeeping. For high visibility, it uses super large digits, 57mm high, for the hours and minutes and smaller digits for the seconds. The large digits use high efficiency LEDs which means they are bright and much more visible from a distance than any Liquid Crystal Display (LCD) could ever be. Nor does this mean they are blinding at night. The circuit senses the ambient light and so the display brightness is maximum in bright light 30  Silicon Chip but becomes dimmer in darker conditions. So visibility is good in virtually all light conditions (apart from direct sunlight). Not only is this clock big but it can also be adjusted for very good longterm accuracy. All crystal-based clocks exhibit some tendency to run fast or slow. Some have a trimmer on the crystal and can be adjusted for better accuracy but they will still drift due to temperature effects over a period of time. Our new design uses a PIC microcontroller and since this is programmed to provide a counter circuit which is actually a clock, we can incorporate a neat feature in the software to adjust the count for even better accuracy. Carefully done, it should mean that the clock keeps time within a few seconds a year – dramatically better than the average watch or crystal clock. The adjustment technique requires you to correctly set the clock and wait a few days to see how accurately it keeps time. Then a special adjustment mode is selected on the clock and the number of seconds the clock differs from correct time (calculated over a period of 60 days) is entered in. However, it is not necessary to wait 60 days and often a day or so is enough to get a good idea of how fast or slow the clock is running. The only requirement is that you then calculate the number of seconds it would gain or lose in 60 days. Of course, the more days you wait, the more accurate the adjustment but you can readjust the figure after a first attempt. Short seconds & long seconds After entering the adjustment figure, the clock then main­ tains time by slightly adjusting the length of a second every so often. If the crystal was running slow, there will be an occa­ sional shorter second to speed up the clock. If the clock was running fast, there will be an occasional longer second to slow down the clock. The actual variation in the seconds is so slight that they will be totally unnoticeable. A short second will be 999ms long, which is 1ms shorter than a full 1000ms second. A long second will be 1ms extra at 1.001 seconds. Internal to the microcontroller, the adjustment figure of seconds per 60 days is divided into the number 10,368 to obtain a reference counter value. For example, if the adjustment figure is 60 (1 second per day), then the reference counter value will be 10,368/60 = 172. This value is compared with a second counter which is increased once every 500ms. When the second counter value reaches the value of the reference counter, the current second is altered by 1ms. The second counter is then reset ready to count up again. For our example value, the second counter will reach 172 after 500 x 172ms = 86,400ms. Therefore, we make a correction of 1ms every 86,400ms which is equivalent to 1 second per day. Thus there will be 1000 correction seconds per day. Note that one day has 86,400 seconds. The number of seconds per 60 days adjustment figure re­quires a positive or negative sign to indicate whether the clock needs to use slow seconds or long seconds. A minus means that the clock is slow and needs speeding up Main Features • • • • • • • • • • • • Large 57mm 7-segment hour and minute displays Easily readable at 20m or more Smaller 14.2mm seconds displays 12 or 24-hour operation Plugpack powered with battery backup Automatic display dimming AM indicator in 12-hour mode Flashing colon between hours and minutes displays Easy-to-use Hour and Minute time setting switches Easy daylight saving adjustment Unique time accuracy adjustment technique requires no equipment Suitable for standard and variant pinout large displays while a plus (no sign) means the clock is fast and will need to be slowed. The adjustment range is from 0 to -255 and from 0 to 255 seconds per 60 days with a 1-second/60 day resolution. This corresponds to 0ppm through to ±50ppm adjustment with just under 0.2ppm steps. The time adjustment mode is initiated by pressing both the hour and minute switches together. The seconds display will then show “Ad” for “Adjustment” and when the switches are released will show the current adjustment figure. This is initially set to “0” and you can increase the number by pressing the hour switch and decrease it by pressing the minutes switch. If the number goes below zero, the value becomes negative as shown by the (-) sign and these negative numbers are used when the clock is running slow. The positive numbers are for fast clocks. You return to the clock mode by again pressing both switch­es and the display will show the time again. If the switches are not released but held down for about three seconds, the display will return to the adjust The prototype was built into a wooden (MDF) case, painted black and fitted with a red Perspex cover. Alternatively, you can build the unit into a folded aluminium case. MARCH 2001  31 32  Silicon Chip Fig.1 (left): the circuit uses an unusual supply arrangement to cope with the fact that IC1 runs from a 5V supply while the large 7-segment displays run from 12V (nominal). IC2 decodes the binary output from IC1 and performs logic level translation. mode again. Note that the time may alter when moving to the adjust mode as you press both switches but the adjustment number will not change when returning to the time mode provided the switches are pressed together within less than about 0.5 seconds of each other. The time will then need to be set correctly once the adjustment mode has been completed. The adjustment number is stored in memory and will be retained unless changed by entering this mode again. You can change the adjust value at any time by re-entering this mode. This may be necessary to adjust the number to set the best figure for accurate timekeeping over a yearly period. For example, if you find that the clock is one second fast every 60 days, you need to add a +1 to the current adjust figure. Thus, if the current adjust figure is -35 seconds/60 day correction, it must be changed using the hour switch to -34. If the original number was 35, then the new value would be 36. Clock setting The time on the clock is set by comparing against a refer­ence clock or the Telstra time service. You can hold the hours switch down so the numbers count up at a nominal 0.5s rate until the current hour is reached. Similarly, the minutes switch can be held down so that the count increases consecutively to reach the current minutes. You then wait until the reference clock begins the next minute and press the minutes switch. It will immediately return the seconds to 00 and set the minutes to the next count. This enables the clock to be set to start accurately. Easy daylight saving Changing to summer time for daylight saving can be a major exercise with some clocks since they require complete resetting of the minutes and seconds to change the hour. Not Parts List 1 processor PC board, code 04103011, 233 x 76mm 1 display PC board, code 04103012, 233 x 76mm 1 98 x 253 x 3mm red Perspex sheet 1 display mask, 98 x 253mm 1 12VDC 450mA plugpack 1 2.5mm PC-mount male power socket 1 4MHz crystal (X1) 4 56.9mm common cathode HE red 7-segment displays (Jaycar ZD-1850, LED Technology D23C4RRR141, Farnell 622-618 or equivalent) (DISP1DISP4) 2 12.7-14.2mm common cathode HE red 7-segment displays (LTS543R or equivalent) (DISP5,DISP6) 4 AA NiCd or NiMH cells with solder tags 2 click-action momentary push-on switches (S1,S2) 1 LDR (Jaycar RD-3480 or equivalent) (LDR1) 1 20-pin DIL IC socket for mounting DISP5 & DISP6 1 18-pin DIL IC socket for IC1 3 16-pin DIL sockets for 8-way pin headers 1 14-pin DIL socket for mounting S1 & S2 3 8-way pin headers 1 2-way pin header 1 shorting plug for 2-way header 4 15mm M3 tapped standoffs 4 M3 x 6mm screws 4 M3 x 10mm countersunk screws 2 blackened 4G self-tapping screws 8 PC stakes 1 1m length of 0.8mm tinned copper wire Semiconductors 1 PIC16F84AP or PIC16F84P microcontroller programmed with clock.hex (IC1) 1 4051 8-way analog multiplexer (IC2) 1 ULN2003A Darlington transistor driver (IC3) 1 7905 -5V 3-terminal regulator (REG1) 8 BC328 PNP transistors (Q1-Q8) 1 15V 1W zener diode (ZD1) 4 1N4004 1A diodes (D1-D4) 2 1N914, 1N4148 switching diodes (D5,D6) Capacitors 1 100µF 25VW PC electrolytic 5 10µF 16VW PC electrolytic 1 0.1µF MKT polyester 1 .0015µF MKT polyester 2 27pF NPO ceramic Resistors (0.25W, 1%) 1 470kΩ 7 220Ω 1 10kΩ 1 180Ω 1 4.7kΩ 7 82Ω 1 2.2kΩ 1 10Ω 1 1kΩ 1 2.2Ω 1W 5% 9 470Ω Miscellaneous Wooden case: 9mm MDF 100 x 235mm, 3mm MDF 98 x 253mm, picture frame hooks Metal Case: 1mm aluminium 347 x 192mm, 4 x 6mm tapped spacers Note: the source code for the clock chip (clock.hex) is available from www.siliconchip.com.au so with the SILICON CHIP PIC Clock. When daylight savings starts, simply press the hour switch ones. When it ends, hold down the hour switch until the previous hour is shown. The minutes and seconds are unaffected and the clock remains correctly set. Returning to standard time is even easier; just momentarily press the hour switch to set it to the next hour. Options The SILICON CHIP Clock is initially set for 12-hour time. It includes an AM indicator at the top lefthand side. You can set the clock for 24-hour operation simply by holding down the hour switch as power is first applied to the clock. The seconds dis­play will show “24” and when the switch is released the clock will be in 24-hour mode. The 24-hour mode will remain selected even if the power is disconnected. To return to 12-hour mode, simply press the hour switch again when power is applied to the clock and the seconds display will show “12”, indicating the 12-hour mode is seMARCH 2001  33 lected. Releasing the switch will start the clock. Although not really important to operation of the clock, there is an option to use two different pinout types for the large displays. We have called the two types “standard” and “variant”. The variant selection is the default. However, you can select for the standard pinout version by holding down the minutes switch at power up. The seconds display will show an “S” for standard and when released will drive the displays assuming the standard pinout. This selection will remain even if power is removed and then reapplied. To re-select the variant display, press the minutes switch at power up and the seconds display will show a “U” for variant (Yes, it’s a “U” but a “V” cannot be made with 7-segment displays). The standard/variant selection also involves inserting the correct links on the display PC board to configure the common cathode pins and the display segments for the two display types. The standard and variant mode selections within the PIC microcon­ troller swap some of the segments so that they show the correct characters. Display dimming In our previous PIC designs involving 7-segment LED dis­plays, we used a simple LDR-controlled transistor to vary the drive voltage for dimming. However, this does not work well with this clock circuit because of the varying number of LEDs used in the display segments. The large displays use four LEDs in series in their segments and two LEDs in the decimal 1/6th of the time (ie, the duty cycle is 16.6%). The dimming feature uses a .0015µF capacitor and LDR (Light Dependent Resistor) associated with pin 3 (RA4) of IC1. The capacitor is discharged each time a digit is about to be lit and the PIC waits until the capacitor is charged before lighting the display. In bright light the resistance of the LDR is low so the capacitor charges up quickly and the display is lit within a very short delay. In darkness or low light, the LDR has a much higher resistance and the capacitor takes longer to charge up, so the duty cycle for each digit is much reduced and it is dimmed down. The actual dimming resolution is about 155 steps from full brightness to minimum. The displays are only dimmed when the clock is in time mode. The displays are at full brightness when in the adjustment mode because the PIC processor has to perform a lot of calcula­tions which do not leave enough time for the dimming function. The clock is powered by a 12V DC plugpack but has battery backup to maintain timekeeping during power outages. During a blackout, only the seconds display, the flashing colon and the AM indicator will be visible Fig.2: two different large 7-segment displays can be used. These are the pinouts for both. points. The smaller seconds digits only have one LED per segment. So if the drive voltage was reduced to dim the displays, the large display segments would be dimmed much more than the decimal points or the seconds digits. For this reason, the display dimming is under software control and we do this by varying the duty cycle of the multi­ plexed signals for the 6-digit display. In a multiplexed display, only one digit is lit at a time but the displays are cycled at a rapid rate so that there is no noticeable flicker. When the displays are driven at full brightness, each display is lit for Table 2: Capacitor Codes     Value IEC Code  EIA Code 0.1µF   104   100n .0015µF   152   1n5 27pF    27   27p Table 1: Resistor Colour Codes  No.   1   1   1   1   1   9   7   1   7   1   1 34  Silicon Chip Value 470kΩ 10kΩ 4.7kΩ 2.2kΩ 1kΩ 470Ω 220Ω 180Ω 82Ω 10Ω 2.2Ω 4-Band Code (1%) yellow violet yellow brown brown black orange brown yellow violet red brown red red red brown brown black red brown yellow violet brown brown red red brown brown brown grey brown brown grey red black brown brown black black brown red red gold gold 5-Band Code (1%) yellow violet black orange brown brown black black red brown yellow violet black brown brown red red black brown brown brown black black brown brown yellow violet black black brown red red black black brown brown grey black black brown grey red black gold brown brown black black gold brown Fig.3: follow these parts layout diagrams to build the PC boards. Note the different link options on the display board for the stan­dard and variant large 7-segment displays. MARCH 2001  35 Fig.4: these diagrams show how the two PC boards stack together for a wooden MDF case (top) and for a metal case bottom. The display board plugs into the processor board via the pin headers, so there is no wiring. because the 12V supply is absent and IC2 does not work. The fabricated clock case is quite compact, measuring 252mm wide, 98mm high and just 40mm deep. It can sit on a desk or hang on a wall. Inside, there are two fairly large PC board stacked together and the backup batteries are on one of the boards. Circuit description The heart of the circuit is IC1, a PIC16F84 microcontroller. This works in conjunction with IC2, IC3 and eight transistors to drive the LED displays. The circuit is complicated by the fact that IC1 needs to operate at 5V while the large displays require a nominal 12V. The different voltage requirements are catered for by connecting the Vdd terminal of IC1 (pin 14) to the +12V rail and the Vss terminal (pin 5) to a +7V (ie, 12V - 5V) rail derived from a negative 3-terminal This is the completed display PC board. Note that two of the displays are mounted upside down (ie, with their decimal point at top, right). The two small 7-segment displays show the seconds. 36  Silicon Chip 5V regulator. IC2 then acts as a level translator (voltage shifter) for the outputs of IC1 so that they can drive IC3 and the large displays. Let’s now look at the circuit of Fig.1 in more detail. Power from the 12VDC plugpack is applied to the circuit via a 2.2Ω resistor and diode D1 which provides reverse polarity protection. The 2.2Ω resistor limits the current into zener diode ZD1 should the voltage go above 15V. REG1 is the negative 5V regulator referred to above. Diode D2, in the GND leg of the regulator, actually sets the output at about -5.6V below the +12V rail but this extra 0.6V is lost via diode D3 which feeds pin 5 of IC1. The 100µF and 10µF capacitors decouple the inputs and outputs of REG1, ensuring its stability. The reason for increasing the output of REG1 to 5.6V is to give a slightly higher “charged voltage” for the backup batteries which are charged via the 10Ω resistor. D3 is included to reduce the supply to IC1 down to 5V (the A version of the PIC is rated at only 5.5V max). D4 is included to bypass the 10Ω resistor when the circuit is powered from the batteries. This lowers the im­ pedance of the battery supply which is desirable when driving a multiplexed display, otherwise voltage variations to IC1 could cause false resetting. Note that there is a link (LK1) between the battery connec­tions to allow the backup supply to be disconnected. This is necessary if you wish to swap between 12-hour and 24-hour modes. IC1 operates at 4MHz as set by crystal X1. The 27pF capaci­tors on the oscillator pins provide the loading for the crystal so that it will oscillate within tolerance. These capacitors are NPO (Negative Positive Zero) types, which means that their temperature coefficient is zero and they do not alter their capacitance with normal temperature variations. Traditionally, clocks have always used crystals which os­cillate at a fre- quency that is a power of 2, making it easier to divide the frequency down to 1Hz using binary counters. The most common value is 32.768kHz, used in watches and clocks. Other values commonly used are 3.2768MHz and 4.096MHz which need to be divided by 100 and 1000 respectively first before division by powers of 2. In our case, we have used a standard 4MHz crystal because it is readily available and the need to divide by powers of 2 is unnecessary when using a microcontroller to provide the clock function. We divide the 4MHz by 16 then by 250 to obtain a 1kHz signal to multiplex the displays. This is again divided by 500 to obtain a 2Hz signal which is used to flash the colon on and off. The seconds display is updated on every second 2Hz signal (ie, 1Hz). The RA4 pin on IC1 is set as an output and is used to discharge the .0015µF capacitor via the 470Ω resistor. When RA4 is taken high, its output is open-circuit and the capacitor charges via the 2.2kΩ resistor and the LDR1. The capacitor charg­es faster when LDR1 is low resistance (in bright light) and slower when the LDR is high resistance (darkness). The charge time is monitored by RA4 and used to control the display dimming described earlier. The RB0-RB7 outputs of IC1 drive transistors Q1-Q8 via 470Ω base resistors. When the outputs are low, the transistors are switched on to drive the segments in displays DISP1DISP6. Segments for DISP1-DISP4 are driven via 82Ω resistors while the decimal points are driven via a 180Ω resistor. The DISP5 & DISP6 The track side of the display board is fitted with socket strips, as shown here. These are fitted with header pins which are then plugged into matching socket strips on the processor board MARCH 2001  37 IC2 can do this because it has three supply connections: the Vdd pin (16) connects to +12V, the Vss pin (8) connects to the -5V from REG1 (ie, 5V below +12V supply) and the Vee pin (7) connects to 0V. As well as acting as the B & C outputs to IC2, pins 17 & 18 of IC1 are monitored via diodes D5 & D6 which connect to the Minutes and Hours switches, respectively. The other side of the switches both connect to the RA3 input (pin2) of IC1. Normally, pin 2 is held low via the 10kΩ resistor to pin 5. However, if a switch is pressed and the B or C line driving the switch is high, the RA3 input will also be pulled high. This signals to IC1 that the switch is pressed. IC1 can determine which switch is pressed because it “knows” which line (B or C) is high at the time. Fig.5: the wooden case is made from 9mm MDF for the sides and 3mm for the base. Construction Fig.6: the metal case is folded up from 1mm aluminium. display segments are driven via 220Ω resistors. Different feed resistors are used because, as already mentioned, the large displays have four series LEDs per segment and two series LEDs in the decimal points, while the seconds displays have only one LED per segment. Upside-down displays Normally, with a multiplexed display such as this, the same segments for each digit are connected in parallel. Hence, the A segments on one digit connect to all the A segments on the other digits. However this clock circuit is not quite that simple. Both DISP1 and DISP3 are mounted upside down and we connect the seg­ments of those digits differently. This has been done to obtain the colon between the hours and minutes digits and the AM indica­tor. Hence, while the centre “g” segments are all connected in parallel, 38  Silicon Chip the “d” segments on the upside down digits connect to the “a” segments on the normal digits and so on. These details are all shown on Fig.1. Note that Fig.1 also shows the pinouts for the standard large 7-segment pinout displays. As noted above, the variant displays have different pin numbers connected but the display will show the same characters when wired up correctly. The common cathode connections to each display are driven via IC3, a ULN2003A 7-transistor array. IC3 is driven via IC2, a 4051 which is often referred to as an 8-channel analog switch or an 8-channel demultiplexer. In this circuit, it has two roles. First, it acts a decoder which converts the binary signals on its three input lines (A,B,C) to drive six outputs, one for each common cathode LED display. Second, it provides logic level (voltage) translation, changing the 5V signals on its inputs to 12V signals to drive IC3. The 12/24 hour large-display clock is constructed on two PC boards, both measuring 233 x 76mm: a processor board (coded 04103011) and a display board (coded 04103012). The two PC boards stack together using pin headers and single-in-line sockets. The boards are housed in a metal or wooden box and we give details for each in Fig.5 & Fig.6. The wooden box measures 98 x 253 x 39mm. The folded metal case measures 98 x 253 x 38mm. Begin construction by checking the PC boards for shorts between tracks and possible breaks and undrilled holes. You will need 3mm holes for the corner mounting and elongated holes for the DC socket. Also the holes for the PC stakes need to be just large enough to provide a tight fit. Before starting, you need to check on whether the large displays you have are the standard pinout or variant type. The two smaller displays will be the standard pinout type. Of the large displays, the Para Light C-2301E (as supplied by Jaycar) have the variant pinout. You can also check the pinout using a power supply (at 12V ) and 2.2kΩ resistor. Connect the negative lead to pin 3 or pin 8 and the positive lead via a series 2.2kΩ resistor to one of the segment pins as shown in the pinout diagram of Fig.2. If each segment lights up when the connection is made then this is a standard pinout display. If not, then it is likely to be The processor board carries the PIC microcontroller and the display driver circuitry. Also on this board are the four 1.2V nicad backup batteries. a vari­ant pinout display. Connect the negative lead to the pin 1 or pin 5 common and check that each segment lights with the positive lead via the 2.2kΩ resistor. Now have a look at the component layouts for the two boards, shown in Fig.3. On the overlay diagram for the display PC board there are several links marked “S” and “V”. Use the “V” links when install­ing the variant displays and the “S” links when installing the standard displays. Do not use both variant and standard links, just one or the other. Also do not mix both types of pinout displays for DISP1DISP4. The links that are not marked should be inserted for both display pinout types. Insert and solder in all the required links on the display board and the processor board. The resistors can be mounted next. Use the colour codes in Table 1 as a guide to selecting the correct value. It is also good practice to use a digital multimeter to check each value. When installing the socket for IC1, take care with its orientation and the same comment applies when installing IC2 & IC3, zener diode ZD1 and diodes D1-D6. The electrolytic capaci­ tors must also be oriented correctly, as shown. REG1 has its leads bent over to insert them into the holes on the PC board and the metal tab is secured with an M3 nut and bolt, with the bolt inserted from the underside of the board. The 4MHz crystal (X1) is laid over on its side and the case has a short lead soldered to it to anchor it to the board. The large displays are mounted directly on the PC board, while the smaller displays are mounted on two 10-way single in-line IC sockets made by cutting a 20-pin dual in-line (DIL) socket into halves. Insert these into the holes for DISP5 and DISP6. Make sure that DISP1 and DISP3 are mounted upside down with the decimal point in the top lefthand corner. DISP2, DISP4, DISP5 & DISP6 are mounted normally, with the decimal point in the lower righthand side. LDR1 is mounted so that its top face is level with the top face of the displays. Switches S1 & S2 are mounted in sockets made by cutting down a 14pin DIL socket into four 3-way SIL sockets. Remove the centre pin with side cutters and insert the sockets in the holes allocated for S1 & S2. The switches are mounted by inserting their pins into the sockets. Inter-board connectors Three 16-pin IC sockets need to be cut into six 8-way sin­gle-in-line strips. The sockets on the processor PC board are mounted normally, with the pins inserted through from the top of the PC board. The remaining sockets strips are mounted on the underside of the display PC board. The pins are soldered to the copper pads, with the socket raised slightly off the board to allow soldering. The two PC boards are then connected together by inserting 8-way pin headers into the sockets and plugging the boards together. The details of how the boards stack together are shown in Fig.4 A 2-pin header is mounted in the link 1 position on the processor board. The 1.2V cells are connected to the PC board using the solder tags. Pass the holes in the tags over the PC stakes ready for soldering. Check that they are oriented correct­ly and solder in place. Testing It is best to check the power supply voltages before in­serting IC1. This is done with just the processor board; ie, not connected to the display PC board. Connect the +12VDC plugpack and apply power. Use a multimeter to check that there is +5V between both pins 4 & 14 and pin 5 of the IC1 socket. There should also be 5V between pins 16 & 8 of IC2. The 12V (nominal) rail should also be present between pins 16 & 7 of IC2. If this is correct, disconnect the power and insert IC1 into its socket, ensuring that it is oriented correctly. Then connect both boards together and reapply power. The display should light and show 12:00. Note that the default selection is for 12hour time and with the variant pinout selected for the large displays. If you are using the standard displays, switch off power and wait about five seconds. Then reapply power with the minutes switch held down. This will then select the standard display pinout. If you want 24-hour time, press the hour switch at power up. Check that the time can be increased with the hour and minutes switches. You can test the dimming feature MARCH 2001  39 by holding your finger over the LDR. Yep, the displays should dim. Press both switches to check if you can access the adjust mode. The initial value is 0, meaning there is no adjustment for crystal frequency. You can now fit the shorting plug for link 1 and this will allow the batteries to charge via the power from the plugpack. Fig.7: this diagram shows the detail of the Perspex panel masking and labelling. Making the case 40  Silicon Chip The clock can be housed in a wooden box or folded metal enclosure. Diagrams for these are shown in Fig.5 and Fig.6. The wooden box uses 9mm MDF (Medium Density Fibre board) for the sides and 3mm MDF for the back. These can be cut to size and glued with PVA glue. The alternative metal box is folded as shown in Fig.6. It is made slightly deeper than the metal box so that the PC board can be mounted onto the rear with 6mm tapped spac­ers. These spacers keep the PC board tracks underneath from making contact with the metal case. Drill holes in the back to mount the PC board in place and a large hole in the side for the DC plug. The clock is assembled using countersunk screws from the rear. A red Perspex sheet mounts over the front, using two small self-tapping screws to hold it in place. A display mask can be used beneath the Perspex to show only the displays and hide the remaining PC board area. Details of the Perspex mask and front panel are shown in Fig.7. We placed a couple of picture frame hooks on the rear of our wooden case so it can be hung on a wall. When your clock is complete, you can set it to the correct time using the time available from Telstra or another accurate source. Run the clock for a period of at least a couple of days to check its accuracy. Then make the adjustment described in the first part of the article. Note that with some crystals that are outside the 50ppm tolerance, you may need to use an adjustment value that is ap­ proaching the maximum range of either -255 or +255. In this case, you will need to alter the crystal frequency slightly. This is done by changing the 27pF crystal loading capacitors on pins 15 & 16 of IC1. If the clock runs fast and the adjustment value needs to be 255 or more, then increase the 27pF capacitors to 33pF each. Fig.8: here are the actual size artworks for the two PC boards. Check your etched board carefully against these patterns before installing any of the parts. Alternatively, if the clock runs too slow and the adjust­ment figure needs to be -255 or greater (ie -256, -257 etc), you have to make the loading capacitors smaller. Use 22pF or 18pF values for each. SC MARCH 2001  41 PRODUCT SHOWCASE Consumer Electronics Show for Sydney Australia's first consumer electronics show, scheduled for Sydney’s Darling Harbour from April 26-29, will give visitors a “sneak preview” into the technology of tomorrow. On display will be the largest collection of consumer electronics and lifestyle technology ever seen in this country. More than 50,000 visitors will be able to experience “hands on” the products which may well change the way we live, work and entertain. The latest MP3 players, DVD tech- nology, personal assistants, ultra-thin laptops, home theatre, GPS, digital cameras and much more will be on display from some of Australia’s (and the world’s) leading manufacturers and distributors. April 26 and 27 will be trade only days, running in conjunction with the CES conference. A program of seminars and practical case studies, designed for industry professionals, will be presented. Keynote speakers will include former PM Hon Paul Keating, Video, mouse & keyboard switchers from Microgram Keenly-priced CD-RW drive from DSE Anyone who has a multiple PC installation will know just how confusing it all becomes before too long: which monitor belongs with which computer? And when you grab the mouse or keyboard, Murphy’s law says you grab the wrong one too! Then there’s the amount of space all these components take up: before too long, all desk and shelf space is gone. That’s why their new KVM Switches are such a good idea. With the touch of a button (or a keyboard hot key) they switch one monitor, one mouse and one keyboard from PC to PC. There are units to control 2, 4, 8 or 16 PCs. More information on the KVM Switches can be found on Microgram’s website or via phone or email. Contact: Microgram Computers Phone: (02) 4389 8444 Fax: (02) 4389 8388 Website: www.mgram.com.au 42  Silicon Chip Dick Smith Electronics has introduced a Mitsumi re-write CD-ROM drive to their range which rivals the prices still being charged for write-only drives. The new drive, priced at $348, is an internal model designed to occupy any spare external drive bay.  offers a highly reliable It 4x write speed, 4x rewrite speed and a very respectable 24x read speed. It supports most international computer standards and formats including Packet Writing, which gives the ability to write multiple times to a write-once disk (until the disk is full, of course). Minimum hardware requirement is a Pentium 133 or higher, 32MB of RAM and Windows 95/98/200/ME or NT4. It goes without saying that this configuration is far below the very minimum entry level machine available on the market today. Dr Hugh Bradlow (Chief Technology Officer, Telstra), Haruyuki Machida, MD of Sony Australia, and Mr John Winstanley, MD of Tandy Electronics. Ticket prices for the public sessions of the show (Saturday and Sunday) will be $13 for adults; children under 15 admitted free. Contact: CESA Phone: Fax: 1800 600 662 1800 600 663 The Mitsumi CD-RW is available from all Dick Smith Electronics stores and DSE PowerHouse stores, or through the company’s DirectLink service on 1300 366 644. Contact: Dick Smith Electronics (all stores) Phone: (02) 9937 3200 Fax: (02) 9888 3631 Website: www.dse.com.au New Altronics Retail Manager Altronics is pleased to announce the appointment of Danny Smith as Retail Manager, heading up the company’s Retail and Mail Order divisions. Danny first joined the Altronics Distribution Centre team three years ago. Quality personal customer service is at the very top of his agenda so please feel free to contact him on your next visit with any suggestions on how the company may improve its service. Alternatively, Danny may be contacted by email at danny<at>altronics.com.au or by telephone on (08) 9328 1599. Pocket reference guide Jaycar Electronics now has available a handy pocket reference guide packed with information regarding solutions to electronic problems and circuit ideas. The compact guide features common formulas, tables and diagrams in place of lengthy text based descriptions. This bestselling guide is full of job-simplifying answers that you can flip to in 60 seconds or less and will become an often-used source of useful information. Contact: Jaycar Electronics Phone: (02) 9743 5222 Fax: (02) 9743 2066 Website: www.jaycar.com.au Tektronix catalog on CD, paper The new 750p a g e Te k t r o nix 2001 Test, Measurement and Monitoring Products catalog features a broad offering of more than 1400 test, measurement, and monitoring products used to design, build, deploy and manage next-generation global communications networks and Internet technologies. Extensive indexes list products by name and by function, as well as by categories such as oscilloscopes, logic analysers, telecommunications and video test. Tektronix sales offices, distributors and representatives are listed in the catalog for easy reference. Measurement product information is also available on CD-ROM. The CD-ROM offers quick and easy access to information, including data sheets and contact information, and provides selection guides and tutorials. Navigation is even easier this year, with no mandatory plug-ins needed to view the catalog. Both catalog and CD can be ordered from the company’s web site. 2GHz RF field analyser from Emona Instruments Emona Instruments have released the Protek 3201 2GHz RF hand-held field strength analyser. With wide-band reception ranging from 100kHz to 2060MHz, reception sensitivity approximately 0-6dBµV EMF, an accuracy of ±25PPM, and maximum scan speed of 12.5 channels per second, the unit is designed for testing, installation and maintenance of mobile communication systems. It is suitable for use with cellular and cordless phones, CB-radios, paging systems, cable TV and satellite reception systems. The backlit LCD display can show a variety of different screens: waveform, center-, span- and step frequency as well as sweep mode, reception mode and much more. It has narrow band FM, wide band FM, AM and single side band (SSB) modulated signal measurement facilities. The PLL tuning system AUDIO MODULES broadcast quality Manufactured in Australia Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 assures precise frequency measurement and tuning. A built-in frequency counter can measure frequencies from 9MHz to 2060MHz. Contact: Emona Instruments Phone: (02) 9519 3933 Fax: (02) 9550 1378 Website: www.emona.com.au Contact: Tektronix Australia Phone: 1800 023 342 Website: www.tektronix.com/mbd/ catalogue_request MARCH 2001  43 SunSeeking Sunflower Last October we presented a solar-powered fly – and it has been a very popular project, particularly for first-timers. Here’s another project in the same vein – an electronic sunflower which senses where the Sun is and turns toward it, just like a real sunflower. Design by Craig Maynard I f you’ve ever been out in the country where a field of sunflowers is blooming, you’ve probably marvelled at the way they all turn to face the Sun as it tracks across the sky. Thousands, perhaps millions of flowers, all facing the same direction. Naturally, they do this to extract the maximum amount of energy from the Sun; energy converted by the plant’s chloroplast. 44  Silicon Chip Words by Ross Tester In our electronic version, two solar cells do a similar job, “catching” the energy from the Sun and converting it into electricity. The electricity is stored in a capacitor and used to turn a small electric motor. The motor is controlled by a comparator circuit which gets its information from a pair of infrared diodes. If the energy being received (from the Sun) by both diodes is equal, it’s a rea- sonable bet that they are both aimed towards the Sun. But if one diode receives more energy than its mate, it’s just as reasonable to assume that it has a better aim than its mate – so the comparator turns the motor on to adjust the direction. It does this in “fits and starts” – it’s certainly not a smooth motion but is quite jerky. In most control circuitry we’d call this “hunting” and steps would be taken to eliminate it. But in the Sunflower, it actually is quite natural. If you’ve ever seen stop-action photography of a sunflower, it does move in fits and starts! The control circuit is not dissimilar to the one used in the Cybug Solar Fly. The main difference between the two circuits is that this one has just one motor, made to turn forwards or backwards, while the other circuit had two motors. By the way, while this project is very much a novelty, the control circuit could be used as the basis for something much more significant – a means of tracking the Sun to charge batteries from a solar collector, for example. In fact, this very circuit can be used to charge a 1.2V NiCd cell! But we’re getting a bit ahead of ourselves! What’s in the kit The kit, available from all Dick Smith Electronics stores, contains all the components you need to build the project. It’s packaged in a see-through box so you can see at a glance what type of flower you’re going to get (yes, there are other flowers than sunflowers!). One nice touch is that all components are mounted on a piece of conductive foam, in the same positions as they will be soldered onto the PC board. (In fact, there’s a paper label glued to the foam which reproduces the silk-screened component overlay on the PC board. You can tell at a glance whether you are missing any components). Be careful when you open the kit The completed Sunflower. Ain’t it pretty? We must confess to a slight error in this photo: the infrared LEDs were bent over before shooting – they should be pointing straight out. And, as mentioned in the text, the (white) wire we used is about 50 times heavier than the wire in the kit, so you could see it. The real stuff in the kit is about as fine as human hair! Shown below is the kit as supplied – that fine line you can see over the paper is the wire! that you don’t lose the length of very fine wire which you’ll need later on! There’s also a short length of brass wire which could be mistaken for scrap! Circuit Operation Sunlight is converted to electrical energy by four devices – the two solar cells (in series) and the two infrared diodes (D1 & D2). The diodes produce very little electricity compared to the solar cells but this doesn’t matter: as long as they produce some, the comparator (U1a) can sense which one is producing the most. If IRD1 on the non-inverting input is producing the highest voltage, the output of U1a will be high. Conversely, if IRD2 is producing more MARCH 2001  45 The Sunflower circuit can be divided into three parts: the solar charger and voltage monitor (Q8); the sunlight direction sensing circuitry (IRD1 & 2, U1a & b) and the motor and driving circuitry (Q1-Q7). Parts List: Sunflower 1 PC board, 62 x 52mm, to be snapped apart (see text) 1 6-15V DC motor 1 artificial flower 1 nylon standoff or bush 1 short length brass wire 1 320mm length 38 gauge enamelled copper wire Semiconductors 2 2N3906 PNP transistors (Q1-Q2) 4 2N3904 NPN transistors (Q3-Q6) 1 MPSA12 NPN Darlington transistor (Q7) 1 34164-3 micropower undervoltage sensing IC (Q8) 1 TLC27L2 dual low power op amp (U1a, b) 2 infrared LEDs (IRD1, 2) 2 BP-37334 1.8V Solar Batteries Capacitors 1 1000µF 16VW PC mounting electrolytic Resistors (0.25W, 5%) 5 100kΩ (brown black yellow gold 1 220kΩ (red red yellow gold) The complete Sunflower kit is available from all Dick Smith Electronics stores, Cat K-3563, for $38.40 46  Silicon Chip voltage, the output of U1a will be low. A high output from U1a will forward bias Q6, which in turn forward biases both Q1 and Q4, turning them on. This allows current to flow through the motor, turning it in the forward direction. Conversely, a low output from U1a turns Q6 off. But it also forces the second comparator, U1b, to produce a high output, forward biasing Q5. In similar fashion, this turns on Q2 and Q3, allowing current to flow through the motor in the opposite direction –which obviously turns it the opposite way. Transistors Q1-Q4 form what is called an “H-bridge” controller for fairly obvious reasons! The length of time the motor turns on (in either direction) is governed by the amount of charge in the main storage capacitor, which in turn is determined by the amount of energy received from the solar cell. When the voltage across this capacitor reaches about 7V, the 34164 voltage sensor (Q8) turns on Q7, allowing current to flow from the H-bridge motor control circuitry. The drain of the motor fairly quickly discharges the capacitor, so once the voltage falls below about 5V Q8 turns off Q7, stopping the motor. The capacitor can then recharge from the solar cells. You have probably noticed that Q7 has a different symbol to the other transistors – in fact, it is two transistors inside one package. It’s called a “Darlington” transistor and has a higher gain than a normal transistor. Don’t mix this up with the other transistors – they all look the same in their TO-92 packages. Construction Before any assembly, we need to snap the PC board into two pieces – one piece holds most of the electronics while the other holds the solar cells and infrared diodes. The PC board is deeply scored where it needs to be broken, so it’s simply a matter of placing the score on a sharp corner (eg, the edge of a desk) and pushing down hard on the board edge – it should break apart very easily. Put the smaller piece to one side. Start the main board by soldering in the resistors, using the colour code guide to make sure you get the right ones in the right spots. Actually, it’s fairly difficult to make a mistake because all except one are 100kΩ. The odd one out (220kΩ) has red and yellow bands on it, whereas the 100kΩ have brown, black and yellow bands. When you snip the excess leads off the resistors on the back of the PC board, don’t throw away them away: Here’s how it all goes together. The four coloured wires in the layout at left (and the white wires below) are in fact the 38 gauge enamelled copper wire (we’ve shown them coloured for clarity). The printed circuit boards are supplied in one piece and must be snapped apart prior to construction. we’re going to need a few lengths of wire later. Next, solder in the 1000µF electrolytic capacitor – it is polarised, with a row of “–” symbols marking the negative lead. The PC board component overlay has the “+” lead marked. Now we move on to the semiconductors. First of all, insert the 8-pin IC in its position, making sure the notch on one end goes to the end marked with a notch on the PC board. Occasionally, you’ll find an IC without a notch but a painted or moulded mark or dot alongside pin 1 instead. ICs are usually soldered in hard down on the PC board. Insert and solder in Q7 in the position shown, after checking and double checking that you have the right one! A close-up view of the solar cells and infrared diodes, mounted on their own PC board. Again, the diodes should not be laid over – they should be pointing straight ahead. Likewise Q8 should be checked then soldered in, followed by Q1 and Q2, then Q3, Q4, Q5 and Q6. Transistors are normally soldered a little off the board – say about 5 to 10mm. The reason for this is that their long leads help keep them cool. The motor is next to go on: it is soldered onto the board “standing up”, with the stripe on the side of the motor going closest to the capacitor. Place the white plastic bush on the motor shaft so that it is about half-way on. It is too big to grip the motor shaft so you will probably need to place a couple of drops of glue on the shaft first (hot melt glue is ideal). But don’t fill the whole of the hole in because that’s where the flower and solar cell collectors go! Now we move on to the smaller board which you snapped off before. Solder the short length of heavy brass wire onto either of the two large holes in the centre of the small board so that it pokes out the back of the board (the side with no writing on it). Now solder in both infrared LEDs on the other side of this board, with their flat sides towards the bottom of the board. They should be about 10mm above the board, not hard MARCH 2001  47 This view of the back of the solar collector assembly also shows a different method of mounting the assembly to the motor: a length of thin brass tube slid over the motor shaft with the brass wire from the solar board soldered to this tube. In some ways this is a better method but will require you to source the tube. down on it. Using some of the resistor leads you cut off before, carefully solder four lengths to the “+” and “–” connections on the two solar cells. The two solar cells mount side-byside about 3 or 4mm apart and stick to the board with the double-sided foam pads already attached to the cells. Remove the backing paper from the cells then carefully push the “–” wire of the left cell and the “+” wire of the right cell through their appropriate holes on the board. When the cells are almost down on the board, align them with each other and then push them down so the foam pads stick. Carefully bend the “+” wire of the left cell and the “–” wire of the right cell back towards the PC board and 48  Silicon Chip solder them to their appropriate pads. Cut off all excess leads. The very fine wire in the kit is used to connect the solar cell PC board to the main PC board, giving plenty of flexibility and allowing it to turn. Note that the wire we used in the prototype is significantly thicker than the wire in the kit – we used this because you wouldn’t see the thin wire in a photograph! First cut the wire into four equal lengths, each 80mm long. The wire is insulated and we need to remove 5mm of insulation from each end. However, it’s rather difficult to remove insulation on wire you can hardly see! The easiest way is to burn it off using a cigarette lighter. But!!!!!! It’s very easy to melt the wire doing this, so be careful. Hold the wire in the blue portion of the flame for a very brief period only. You should be able to “wipe” the burnt insulation away with your thumb and forefinger, leaving bright copper coloured wire. Solder one end of each wire to the positions on the small board marked Sol+, Sol–, IR1 and IR2. The solar collector board is now finished and we move on to final assembly. First, bend the thick copper wire down 90° about 10mm out from the back of the board. The angle of the wire to the board should be such that the solar cells (and of course the board) is about 45°. Both this wire, and the wire “stem” of your sunflower poke into the hole in the top of the plastic bush. The two wires between them will probably be a fairly tight fit but if not, a drop or two of hot-melt glue will hold them in place. Angle the flower so that it aims the same way as the solar cells but not so that it covers them! Finally, solder the ends of the four very fine wires to their respective positions on the main PC board – Sol+, Sol–, R1 and R2. Your solar-powered sunflower is now finished. You’ll almost certainly find it does absolutely nothing indoors (unless you have direct sunlight streaming in a window!). Take it outside, though, and you should find the flower starts moving around, looking for the Sun. What it it doesn’t? Obviously, there’s a mistake somewhere. With your multimeter, check that you have output from the solar cells – probably several volts in direct sunlight. If so, check to see if there is voltage across the electrolytic capacitor and that the output of Q8 swings up and down. If you have output from the solar cells but nothing on the capacitor, the chances are one or more of the very fine wires are either broken or not soldered properly. Check that the output of U1a (pin 1) goes high or low as you cover and uncover each of the infrared diodes. If all these checks prove correct, the odds are that you have one or more of the transistors in the wrong place. SC It won’t work if you have! SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. 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Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 PRICE GUIDE- Subscriptions YOUR DETAILS (all subscription prices INCLUDE P&P and GST) Your Name________________________________________________________ (PLEASE PRINT) Organisation (if applicable)___________________________________________ Please state month to start. 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Folded: $A5.95 inc p&p within Australia; elsewhere $A10 inc p&p. *BOOKSHOP TITLES: Please refer to current issue of SILICON CHIP for currently available titles and prices as these may vary from month to month. SUBSCRIBERS QUALIFY FOR 10% DISCOUNT ON ALL SILICON CHIP PRODUCTS AND SERVICES* *except subscriptions/renewals and Internet access Item Price Qty Item Description P&P if extra Total Price Spec i SUB al Offer SCR IBE & COM PUTE GET R OM FO N Aust R FREE! IBUS ralia Only* Total $A TO PLACE YOUR ORDER Phone (02) 9979 5644 9am-5pm Mon-Fri Please have your credit card details ready OR Fax this form to (02) 9979 6503 with your credit card details 24 hours 7 days a week OR Mail this form, with your cheque/money order, to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy, NSW, MARCH 2001  57 Australia 2097 * Special offer applies while stocks last. 03-01 SERVICEMAN'S LOG Meet me on the reset line, Sony One of the advantages of working for a main brand dealer is that you get to see the newer models first and you get free service manuals too – not to mention technical support. Unfor­tunately, that doesn’t help when it comes to fixing tricky problems. Recently, I was doing some work for our local Sony agent and a couple of “newish” flat-screen TVs came in. Now when I say flat screen in this instance, I don’t mean plasma displays. I mean flat-front glass CRTs in silver cabinets as used in the Sony KV-XF29M35 (BG-3S chassis SCCU24A-A). This set is actually circa 1999 but looks brand new and has great performance. It’s also considered to be a really reliable model, so I was surprised when two came in together with different faults. The first had no sound, which seemed easy enough, so I decided to fix this one first. This actually turned out to be no TV sound – all the AV inputs and outputs worked OK, as did the volume control and all the 58  Silicon Chip on-screen sound menus. Armed with an audio probe, I quickly confirmed that there was no output from the tuner/IF/decoder block (TU101) at pins 30 and 31. However, touching this point resulted in a healthy hum from the speakers. I then set the TV into its service mode with the remote sequence: “Display” - “5” - “-Vol +” - “Power” and checked the data displays with that of the manual. In particular, I looked at anything to do with the sound; eg, OPB (Optional Bits). I also made sure that CCIR B/G PALD was selected as the TV system. Everything was correct, so I felt it just had to be the tuner/IF/decoder (TU101) that was faulty. I ordered a new one in and fitted it but it made no difference – there was still no sound from the tuner IF decoder. So much for my snap diagnosis. There really wasn’t much left to check apart from the supply rails to the various pins. First, I had to get the chassis into a safe service posi­tion. This isn’t easy but with the rear end on the bench and the rest of the chassis up in the air, I could finally access the PC pins on the tuner pack. There are supposed to be 31 pins but nine are not connected, which makes it very difficult to determine which pin is which. I began by confirming that the 5V, 9V and 30V were present. I also found the SDA and SCL digital buses to be 4.75V each, with activity indicated on the CRO. The picture was perfect, so the RF AGC (automat­ic gain control), AFT (automatic fine tuning) and VIF (video intermediate frequency) connectors had to be OK. So what was left? Well, “NC” normally means “no connection” to me but the circuit indicates that these pins are connected! I felt that they needed investigating but there was also PLL-SW and DET OUT (detector out) signals to check – and what if the output load was affecting something? The circuit also shows IC203# but the “#” means that the device isn’t fitted in this model – and it wasn’t. Clasping at straws, I swapped over the B3 Audio Processor/AV switch from the other set but it made no difference. The DET out (pin 22) goes via R105 to transistor Q101, which provides the video output signal. This was OK but what about the PLL-SW on pin 23? Well, this went via R29 1kΩ to pin 27 of microcontroller IC001 and this pin is marked on the circuit as “0V” and “ST” (for stereo). However, I measured the voltage on this pin as 4.9V, so at last I had a clue. Similarly, there were three other pins on the microcon­troller that were of interest: pin 29 (mute) at 0V; pin 28 (SAP = Sound Audio Processor?) at 0.3V; and pin 26 (audio switch forced mono) at 4.9V. The latter is connected via R030, R108 and R103 to pin 26 of the tuner but it is all marked “#” which again means “not fitted”. The “VOL CONT” line from pin 49 of IC001 to tuner pins 17 & 25 checked out OK too, in that R104# and R107# are not fitted. This all took time to investigate and I also changed IC001 and its companion EPROM (IC003) to no avail. By now, I felt that I had already gone the extra mile for what was, after all, a simple problem. I was getting nowhere except for the incorrect voltage on pin 27 of the microcon­troller. I tried shorting this out but it made no difference – there was still no sound. All I had left were the nine “no connection” pins on the tuner to check out; ie, pins 16-20, 24-26 and 29. In fact, I had already checked most of these but there was one left that I had overlooked. This was pin 24, the Reset line, which measured 1.7V. This was an interesting value as it was neither really a low (0V) nor a high (at 5V). I tried shorting it alternatively to Ground and the +5V rail but the sound still stubbornly refused to come on. In operation, the Reset pin (pin 24) is supposed to go low for a fraction of a second and then rise to 5V. This pin is connected to IC100 (580743AL), which is a surface-mounted device, via D100. The Items Covered This Month • • Sony KV-XF29M35 TV set (BG3S chassis SCC-U24A-A). Panasonic TC-48P10 TV set (M15L chassis). time constant is determined by C104. I tried heating and freezing the device and then switching the set off and on. Suddenly there was sound! Replacing IC100 completely fixed this awkward fault. The second Sony The second Sony came in with the initial fault of being intermittently dead and, surprisingly, an intermittent pink menu! This latter symptom really had us amazed, as there is no menu to change the colours from the normally blue, white, black and yellow. The picture and sound were otherwise perfect. In the end, this set was fixed by a team effort, with no less than four technicians having a go. Perhaps it might have been better if one person had stayed with it all the time but it changed hands several times due to various circumstances within the service company; ie, the Christmas rush, illness and even a retirement. The first technician noticed that tapping the set would make it go on and off and change the menu colour. By careful trial and error, the sensitive area was reduced to the Teletext module (V1), so he removed the module and reworked it completely. Afterwards, when it was refitted, the set no longer seemed to intermittently switch on and off but the menu colour still re­quired attention. After a lot of consultation, he decided to replace the Y/C Jungle IC (IC301, CXA2130S). By the time the IC arrived, techni­cian number two was now on the job and he replaced the high-density 48-pin device. This wasn’t all that easy because there were lots of surface mounted components around it. However, although I didn’t observe him do it, the completed job looked fine – the only trouble MARCH 2001  59 Serviceman’s Log – continued resistor, had a tiny solder dag that was just shorting to pin 12 of IC001. This pin is normally grounded, which explains everything – no wonder the voltage stayed low. Still, it’s a wonder to me that no-one (including yours truly) picked it up. It made me and the other two technicians look a bit stupid and the new guy is well in with the service centre. Still, such is life and he deserves it. Jousting with Phil was that the set now didn’t work at all! It was completely dead. It was now that I was given the job. Thanks, mate! The first thing I did was examine it very carefully every­where there was fresh solder. The guy had done an excellent job and had also reworked microcontroller IC001 as well. The exact symptom we had was that the power LED (D3906) on the H3 function board came on yellow but nothing else, which only implies that there is voltage on the +15V standby line. I fished out the meter and started at the power supply to find that the standby voltage was low (at 7V). And although it was arriving at pin 4 of IC002, nothing was coming out on pin 5, so I ordered a new MM1319AFBE 8-pin surface mounted IC. When I refitted the new one, the 5V was there initially but dropped over a period of 15 minutes. Despite unsoldering many of the pins of the microcon­troller, EPROM and jungle ICs, it made no difference. I 60  Silicon Chip was informed that it was essential for the SDA and SCL data lines to be at 5V for the set to work. I ordered and fitted a new EPROM and microcontroller IC but it made no difference. I then tried disconnecting as much as I could from the 5V rail but was getting nowhere. By now, we were beginning to discuss whether or not the set should be written off. We had already wasted too much time on it for the job to be economical. Fortunately, about this time, a new technician was hired to replace the bloke who had retired. The new boy on the block had to be tested, so he was given this set to see what he was made of – not that we were really expecting anything much in view of the problems we were having. To our astonishment, he had the set working in half an hour! So what was the problem? He had found that the reset line from IC002 to the microcontroller was the source of the problem. R043, a surface-mounted It was a gorgeous day; too good to be working in fact – but hey, isn’t every day? I was on my way to fix a set for Phil, an old client of mine. Phil’s set is a Panasonic with a TC-48P10 M15L chassis. It’s an old set but so are we - and I like the guy. I pulled up outside his place and he was digging in the garden. “Finally buried your missus, Phil?”, I quipped. “Nope – I’m preparing it for you”, he replied, “in case you charge too much”. “Now, now”, I countered, “you know I only charge you double what it’s worth!” “Yup, that’s why I’ve got to get you listed down on my tax form as a dependant”, he shot back. Anyway, down to business. Phil’s set had no picture but the raster and sound was there and also the On Screen Display. All these series of Panasonics look very similar. They are housed in black plastic cases with the same controls on the front and their features can be confusing. I asked for his remote control. “You’ve still got it from last time”, he replied. I let that comment slip by and when I removed the back I could see that it was my mistake – this set was a “non-remote” model and no IR receiver was fitted. Unfortunately, there are no AV inputs to try an external source of video, so really there wasn’t much I could do without an oscilloscope. I knew I was going to get some verbiage when I told Phil the good news about it going to the workshop but it had to be. He made a few comments about “licensed thievery” and I gave him back as good as I got. Back at the shop, I fired up the CRO and followed the video from the video detector (IC101, pin 19) to Q601, Q302 and finally pins 15 & 16 of IC601 (AN5601K), the Y/C jungle IC. But there were no RGB outputs from pins 24, 25 and 21. By now, I was feeling pretty confident about an early and easy outcome to this problem. I was sure that it was all a matter of beam limiting and/or contrast control that was the cause. The most common suspect is R525 (12Ω) which goes high but it proved to be OK in this case. I checked the subcontrast con­trol (R302) and found that the voltage on pin 6 of IC601 varied over the expected range (ie, 2-4V). Similarly, the voltage range for the brightness control checked out OK on pin 18. By now, all the obvious causes had been eliminated so I ordered in a new AN5601K and laboriously replaced this 42-pin high densi­ty IC. To my dismay, this only made things worse because it took away the on-screen display. Suspecting a crook new IC, I obtained another one but it made no difference. Despite the access difficulties, I decided to make a series of voltage measurements on the underside of the IC. To make things easier, Mrs Boss wrote down the results as I proceeded and compared them with what they should be. In a fault condition, you can’t expect the two sets of fig­ures to exactly match but you can make a note of the ones that are significantly different and then examine the circuit for clues. Most of the readings were very close to the chart in the manual (which, I might add, was for a different model but was the only one with the voltages drawn). For some reason, The TC-48P10 manual doesn’t show voltages. The significant voltage was on pin 14 (“DATA BLK”), which should have been 0.1V but was in fact 1.1V. It was only 1V out but this was my only real clue – that and the fact it was connected to some sort of blanking control circuit which might give the symptoms I was getting. Pin 14 is connected via D604 to R641 and the 12V rail. It also goes to Service Switch S601 via D604. I could measure 1.7V on the anode of D604 but hang on – in the Normal position of the Service Switch this pin should be connected to ground? So how was this possible? The ohmmeter didn’t measure low resistance to ground either, so I reasoned that the problem had to be in the service switch S601 itself. This was a blow, as I doubted I could get this as a spare part from Panasonic considering its age. Anyway, I removed the switch assembly and dismantled it but could find nothing wrong with it apart from the fact that it needed a bit of a clean. I reinstalled the switch but nothing had changed, so I measured the connection at the switch and at the junction of R641 and D604. This revealed that there was no continuity between these two points so there had to be a break in the copper track on the PC board. I couldn’t see any break but by following the very fine track and scraping away the Shellac every few centimetres, I finally narrowed the break to a very slightly discoloured 2.5mm of track. Fitting a fine wire link across this section restored the circuit and the picture. For some reason or other, this section of track had corroded right through. Now the only problem was letting Phil know the cost of reality. Yes, I know I am in for a real hard time! SC With one of these . . . ...you could have one of these in about 1 HOUR! Introducing The Quick Circuit 5000 If you want fast, no-fuss PC-board prototypes, take a look at the Quick Circuit 5000. This PC-controlled milling machine reads the standard files generated by popular PC design packages and mills away the copper on the board to produce the tracks. It then drills the holes and cuts out the finished product. You can go from design to finished product in about one hour – without using any messy chemicals. Check out the November 2000 issue of SILICON CHIP for a full review Phone SATCAM on (02) 9807 7081 or email satcam<at>ozemail.com.au MARCH 2001  61 All-in-one Parallel Port P Checkerboard By David Deer W e’ve published several PIC programmers in recent years – the most recent being just two months ago (January 2001). So why another, so soon? Simply that this one does even more than the previous ones – as well as providing the circuitry to download assembled code from your PC parallel port into a 16C84 or 16F84 PIC Microcontroller, it also has comprehensive test facilities inbuilt. Few things are more exasperating than writing what looks like great code, programming it into the PIC, moving the chip to the project board and . . . nothing. Or something that’s not supposed to be. Or almost something. But not the something you intended. With this project, all programming and checking can be undertaken without having to move the PIC chip until you’re happy with its operation. Although the circuit may look complex, this board is relatively simple and, as we discuss later, you don’t need to install all components initially – only those you need for the functions you need. And with the exception of the PC board itself and possibly the PIC ZIF socket, most (if not all) of the components should be available “off the shelf” at your local lolly shop. RCS Radio in Sydney (02 9738 0330) will have PC boards available shortly after publication. Some features explained Starting at the D-25 input socket (CON2), there is IC1, a 7407 hex buffer (yes, 74 series, TTL! They are still available – eg, Jaycar Cat ZS5807). It provides a buffer between the computer and the microcontroller and provides compatibility with the easy-touse MPASM-WIN.PIC Assembler and PICPROG2. PIC Programmer software. See how to obtain this Windows 95/98 compatible software, free, and 62  Silicon Chip suitable code to program a chip (for demonstration purposes) later in this article. Some of this buffer circuitry was derived from the Classic PIC Programmer published on the Internet by David Tait. The 4-pole 3-position rotary switch provides a “code loading” facility when in the anticlockwise position, a centre “off” position to ensure iso- on each input bit, since these bits can also be used as outputs when required. These LEDs can be switched, by means of changeover switches S11 and S12, to show either colour to indicate if the chip bits, configured as output bits, are high or low. Red indicates a bit is high while green indicates a bit is low. The highs and lows can also be displayed simultaneously, with some Reproduced same size, this early prototype of the PIC Programmer is slightly different to the final version shown in the circuit and component layout over- lation between the computer port and the board components, plus a “run” facility when in the clockwise position. To alter or debug the code in a chip, apart from modifying the code in the software, it is only necessary to switch to the load position, download the modified code, and simply switch back to the run position to see the result. A dual colour (red/green) LED is provided on each output bit and also reduction of intensity, by selecting the “Bi-colour” position for switch S12. To obtain the high only output bit display, S11 and S12 are switched towards the D input socket end of the board (ie select “Red” and “Red/ Green” respectively). To obtain the Low only bit display, toggle S12 towards the D input socket end of the board and toggle S11 towards the opposite end (ie select “Red/Green” and “Green” respectively). PIC Programmer and Could this be the ultimate PIC programmer? It’s got to come close. Use it to download code from your PC – and then use it to check if the PIC does what it is supposed to! All inputs and outputs can also be held high or low to provide any required parameter to check code functions. DIP switches are interposed at all necessary positions to provide individual control for all these items and a bank of push buttons provide high and/or low inputs as required. An “interrupt” facility, using two of the inverters in IC3, a 74HC14 hex Schmitt trigger to provide a non- stration code for this project does not require a buffer jumper to be in place. Four sets of headers are installed on the board to provide connections to other circuits being set up to accept the programmed PIC chip. The 10 pin header (CON3) provides facilities to connect the programming circuitry to a microcontroller installed in a circuit on a remote project board, providing of course the project board leaf. All components mount on the one PC board, with the board layout corresponding fairly closely to the circuit diagram’s “flow”. bounce circuit, gives a choice of either a rising or falling edge interrupt, selected by a jumper shunt. Because pin 3 (bit RA4/TOCKI) of the PIC chip provides only an open gate-type function when used as an output, two more of the 74HC14 inverters are used to provide either an inverted or non-inverted buffer to drive the LED connected to this pin. Again, this is selected by a jumper shunt, when required. The demon- also contains a similar header or means of connecting its appropriate chip pins to this programming board. It allows a ribbon cable to remain in place and the Load/Run switch to be used as if the remote chip was on this board; ie, no unplugging or disconnection required to program or debug the remote chip. Pole 4 of DipSw1 will disconnect supply to the 10-pin header and to the Load/Run switch. Pole 4 should be left on at all times that a chip is being used in this board, because the Load Run switch provides isolation during programming, but should be off for remote in-circuit programming via the 10-pin header. Pole 1 of the 4 pole DIP switch will completely disconnect the MCLR bit from this board’s supply when then 34-pin header is used to connect a chip on this board to a remote project board. Being available, poles 2 and 3 are used to control the 13V and 5V supplies, respectively, to the 34 and 20-pin headers. The 34-pin header provides a means, via say a computer IDE cable, to connect all the input and output pins of the microcontroller on this board to another project board (eg, the LCD module shown at the end of this article). The 20-pin header and the 16-pin header provide similar connections but connect only either the outputs or the inputs respectively. All the headers also provide both an earth connection and a +5V supply connection and the 34-pin header also provides a 13V supply. All the supplies provided at these headers are controlled by switches. The supply, by the way, is derived from a 12-14V AC or 15-18V DC input. This can be from a 200mA or so plugpack. The rectified supply is filtered by a 2200µF capacitor and regulated to around 13.5V by the 7812, with two silicon diodes in series, raising the ground pin above 0V by about 1.4V. This nominal 13.5V rail is further regulated to 5V by the 7805 positive voltage regulator (REG2). LEDs 5 and 6 are high intensity, 5mm types and provide some indication that the programming function is in progress. They can be any colour but being high intensity types need only a small current and hence do not interfere with the download procedure. LEDs 1, 2, 3 and 4 are simply MARCH 2001  63 REG1 7812 F1 300mA DB1 W04 IN + 1000F 25V CON1 DC SOCKET .01F REG2 7805 OUT GND IN 10F 16V D1 1N4004 _ 12 - 14VAC/ 15 - 18V DC INPUT .01F LED1  D2 1N4004 LED2  +13.5V +5V 10k 5 14 11 IC1a 7407 B IC1b 7407 10k B E C 2 1 2 1.6k 0.1F +5V S4 RESET 10k LED6  5 10k 100 IC1d 7407 470 5 6 RC RA4/T0CKI JP1 16 15pF IC1e 7407 13 12 RB0/INT RB1 S3d 10k 4 7 S3c 18-25 A 14 S3b 13 S3a LOAD 7805 7812 12 RUN 1 2 3 OSC2 15pF 10k 18 IC2 PIC16F84 (ZIF SOCKET) 15 +5V 17 OSC1 X1 4MHz 470 RA2 VSS RA3 XTAL 3 RA0 0.1F 10 A RA1 VR1 500k FREQ ADJUST +5V 10k 330 +5V 1.8k IC1c 7407 S2 LED4  LED5  Q2 BC558 +5V 10k S1 330 330 100k 4 3 LED3  1.6k Q1 BC558 5.1k 4 TO PC PARALLEL PORT E C +5V +5V 10k .01F +13.5V 100k 10k 10 10F 16V 0.1F +5V CON2 D-25 OUT GND MCLR RB2 VDD RB3 RB7 RB4 RB6 RB5 6 7 8 9 10 11 CON3 BC558 1 IN OUT GND E B C BI-COLOUR (RED/GREEN) LED RED CATHODE LED K 10k +5V 1 +13.5V 2 3 A DIPSW1 4 SC 2001 PIC PROGRAMMER 64  Silicon Chip A +5V 10k DIPSW2 4 10k 5 10k 6 10k 4.7k S10 INTERRUPT .01F 8 7 IC3a 74HC14 DIPSW3 S5 JP2 1k 1 10k S6 10k S7 10k S8 10k S9 1k 330 LO 1k 3 1k 4 +5V 1k 5 10k JP3 .01F FALL 6 CON4 2 7 HI 1k 2 14 1 RISE IC3b 74HC14 4 330 3 7 DIPSW4 CON6  120 LED7 1 120   120     LED8 2 LED9 3 120 LED10 4 11 5 +5V IC3d 74HC14 6 7 1 100k JP4 INVERT 9 IC3c 74HC14 NONINVERT 8 120 8  DIPSW5 CON5  10 JP5 LED11 120   120   120   120   120   120   120   120   1 2 3 4 5 6 7 8 LED12 LED13 LED14 LED15 LED16 LED17 LED18 LED19  RED DIPSW6 1 2 3 5 4 8 7 6 S11 GREEN RED/GREEN S12 BI-COLOUR D5 1 1 10k +5V 10k 10k 10k 10k 10k 10k 10k D3 1N4004 D4 D6 D7 D8 47 D9 1N4004 5 x 1N4148 MARCH 2001  65 Parts List – PIC Programmer 1 1 1 4 5 1 1 5 1 1 1 2 1 2 1 1 1 1 5 2 1 1 1 1 1 4 2 PC board, 241mm x 93mm, code LDDPP1 4-pole 3-position sealed rotary switch, PC mounting knob to suit switch SPDT PC mounting slide switches momentary push-on switches, snap action, PC mounting 4-pin type, red momentary push-on switch, snap action, PC mounting 4-pin type, yellow momentary push-on switch, snap action, PC mounting 4-pin type, green 8-pole DIP switches 4-pole DIP switch DC power socket, 2.5 mm, PC mounting D-25 male socket, 90° PC mounting 14-pin IC sockets 18, 20 or 24-pin ZIF IC socket (or 18-pin dual wipe contacts IC socket – see text) micro “U” TO-220 heatsinks (eg, DSE H3403) 34-pin dual-in-line snap-off pin header set 20-pin dual-in-line snap-off pin header set 16-pin dual-in-line snap-off pin header set 10-pin dual-in-line snap-off pin header set jumper shunts, 2.54mm 3mm x 6mm screws, nuts and washers (or similar) parallel port extension cable (D-25 male to D-25 female) plugpack supply, 12-14V AC or 14-18V DC, about 300 mA. (or similar) metre very light insulated hook-up wire (for board links) pair M205 PC-mounting fuse clips 300mA M205 quick blow fuse PC stakes TO-220 insulating kits (for regulators) Semiconductors 1 7407 hex buffer (IC1) 1 16F84 PIC microcontroller (IC2) 1 74HC14 hex Schmitt inverter (IC3) 1 7812 12V regulator (REG1) 1 7805 5V regulator (REG2) 2 BC558 PNP transistors (Q1, Q2) 2 3mm red LEDs (LED1, LED3) 2 3mm green LEDs (LED2, LED4) 1 5mm high intensity amber LED (LED5) 1 5mm high intensity red LED (LED6) 13 5mm dual colour (red/green) two pin LEDs (LED7-LED19) 1 WO4 bridge rectifier (or similar) (BR1) 4 1N4004 diodes (or similar) (D1-D2, D3, D9) 5 1N4148 diodes (or similar) (D4-D8) 1 4MHz crystal (XTAL1) Resistors (0.25W, 1%) 3 100kΩ 29 10kΩ 1 5.1kΩ 1 1.8kΩ 2 1.6kΩ 6 1kΩ 2 470Ω 4 330Ω 12 120Ω 1 100Ω 1 47Ω 1 500 kΩ Trimpot (Piher Horizontal or Spectrol 25 turns) Capacitors 1 2200µF 25VW PC-mounting electrolytic 2 10µF 25VW PC-mounting electrolytic 3 0.1µF MKT polyester (code 100n or 104) 5 .01µF MKT polyester (code 10n or 103) 2 15 pF ceramic (code 15p or 150) 66  Silicon Chip provided to indicate the state of the power supplies and power switches and can be any colour, 3mm or 5mm, normal types. (3mm LEDs use less space near the ZIF socket operating lever/knob). All the push buttons are readily available snap action, 4-pin, momentary (push on). The PIC 16F84 chip supports several different types of clocking oscillators including crystal, ceramic and R/C (resistor/capacitor). The board provides for installation of any these types of clocking oscillators, connected to pins 15 and/or 16 on the chip. The appropriate type is selected by a jumper shunt. The demonstration program code requires a 4MHz crystal and hence this should be selected at this stage. In the R/C configuration, either a Piher horizontal or a more sensitive Spectrol 25-turn trimpot can be accommodated. If you mount the R/C oscillator capacitor and/or crystal in sockets, you can swap them at will to provide a huge frequency range. These sockets (in sets of three) could be cut/broken from a gold insert machine pin IC socket or strip. The program code can be easily altered to run with the R/C oscillator variant but the time between operations will be considerably different unless the delay sections of the program code are also altered. The board uses a normal printer extension cable to connect with the printer port, or any parallel port, on the computer. The software seems to favour the LPT1 port, so use this port if possible. The printer extension cable should be just that, male at one end, female at the other end, with no crossovers. Construction The placement of components shown on the component overlay fairly closely follows their relative positions on the schematic diagram. Note that the whole of the board need not be completed at one sitting. Various components can be sourced and added as required. To keep the cost of the PC board at a reasonable figure (ie, single sided), there are quite a few links to be installed and it is best to install these first. The links that are close together should be insulated. However, having obtained the PC board, it is only necessary to initially install a socket for the microcontroller and install the components shown on the circuit diagram which connect to pins 4, 5, 12, 13 and 14 of the microcontroller, in order to be able to download a program to the microcontroller. These components include the 25-pin D socket, DC supply socket, bridge rectifier, 7805 and 7812 voltage regulators, the 7407 (IC1) , Q1 and Q2, the 4-pole 3-position rotary switch, the 4-pole DIL switch, and all the associated resistors and capacitors. The easiest socket to use is an 18-pin ZIF (Zero Insertion Force) socket. These may not be too easy to find - ours came from Futurlec (www.futurlec.com). The board will also accommodate 20 or 24-pin sockets, if you happen to have one or can get one more easily than an 18-pin. However, for 20 and 24-pin sockets, the excess pins are not used – they can be soldered to the board if you wish. That means only pins 1 to 9 should be counted, (on one side) and the pins opposite to these should be considered pins 10 to 18. Any reference to pin or bit numbers in this text, or on the circuit diagram, assume that we are counting the pins as if numbered 1-18 in an 18-pin socket. When fitting the PIC to the socket, pin 1 is the pin nearest to the voltage regulators. 20 and 24-pin ZIF sockets are also available at Farnell Electronics, 72 Ferndell St, Chester Hill, 2161. Phone 1300 361 005. If a 24-pin socket is used, ensure it will accept an IC with 0.3in row spacing. Yes, ZIF sockets are relatively expensive but their ease of use is worth the one-off additional cost. An alternative cheaper arrangement is to use a dual wipe contacts socket and mount each microcontroller chip on a machine pin socket which will protect the chip pins while being inserted and withdrawn a number of times. Of course, installation of all the remaining components on the board will dramatically reduce the number of times that a chip would be required to be inserted and removed and will also allow the demonstration code written for this article to be run without having to remove the chip from its socket. But ultimately, removal is necessary. It may be necessary to slightly enlarge the holes in the board for some components such as the rotary switch and the DC power socket. This is easily done with suitable size drills and a pin vice or similar device. The PC board will accept the PCB-mount, SPDT changeover switches available from most supply houses. Again the mounting holes in the board may need to be slightly enlarged. The voltage regulator heatsink fins should be bent slightly inwards to ensure they do not touch. Insulating the heat sinks from the regulators, while not essential, is preferable. The next most obvious components to fit are the display LEDs, along with the oscillator components at pins 15 and 16 of the PIC chip socket. Also the LED DIP selection switches, resistors, diode strings and switching system (S11 and S12), to obtain indication of either High or Low 4.7k 1000F Fig.2: the PIC programmer component overlay, reproduced same size to make construction as easy as possible. Note that there are differences between this and the photograph! MARCH 2001  67 Main input and output to the programmer itself is through a D25 socket which connects to the parallel port of your PC. But there is also a wide range of pin sets to and through which you can connect external devices. bit outputs. The 74HC14 IC is necessary to initiate the interrupt function. The remaining DIP switches, resistors and pushbutton switches which allow holding or pulsing all the inputs and/or outputs high or low can be added as required. Similarly, the various headers can be added as needed. Programming a PIC chip (See also the “.txt” documents incorporated in the software downlo ads). By choosing appropriate software, almost any computer can be used to program a 16F84 or 16C84 PIC chip. Mpasmwin.exe and PICprog2.exe is assembly and download software respectively and run OK in Windows 3.xx and 95/98. For DOS users, Mpasm.exe and PICprog.exe can be used instead. All this software and a demonstration code file, named Miela.asm, can be downloaded from the SILICON CHIP web site in a file named LDDProg.exe. Download this self-extracting zipped file (of about 560KB), double click on it and it will go into a folder named LDDProg, which it will create on your C drive. LDDProg has two subfolders, DOS6xx and AllWins, and a Readme1. txt file. The Readme1.txt will open in Windows NotePad, or DOS Edit, and explains what to do with the two sub-folders. A further Readme.txt file in each subfolder details the relatively simple steps to use the application software to assemble and download the demonstration file, Miela.asm, to a 16F84 PIC microcontroller. Unfortunately the extraction process will only work in Windows 95 or 98. If you have to use DOS to assemble 68  Silicon Chip code and to program chips, it will be necessary to have access to a suitable computer running Windows 95/98 to extract the files and then transfer the appropriate files to the DOS computer. For those readers who have acquired the PC board but are not in a position to download the software, the author is prepared to supply the file LDDProg.exe on a floppy disk. Send a $1.00 stamped, self-addressed, Computer Disk Postpak to Mr. LDDProg at PO Box 114 Emu Plains, NSW 2750. But please allow about a week for the reply. This offer will only last for six months from the date of issue of this month’s magazine. The Assembly code ( Miela.asm) will animate the LEDs on the completed board. This file can be read and/or edited in Windows Notepad or in a DOS edit screen. By the way, Miela is my 2-1/2 year old granddaughter and it took her only a few minutes watching while I was running and debugging the Miela. hex code on the board to realise that pushing the Reset button started the LED chasing sequence and, after two sequences, the chase stopped with the bit 6 LED switched ON. (Actually the PIC switches bit 6 high and goes into the Sleep mode). By pressing the Interrupt button while the PIC was in the sleep mode, she was able to send the LEDs into a frenzy of flashing before settling down to a chase and into the sleep mode again. Although not the intention of the project or code, it kept Miela interested for a considerable time until I hid the project to divert her attention elsewhere. I then decided a suitable name for the code would be Miela. Your .asm codes can have any file name, preferably with the usual DOS requirement of 8+3 characters, but .asm must be used for the extension characters so that Mpasmwin.exe or Mpasm.exe will recognise it. PICProg.exe or PICProg2.exe, as appropriate, can be used to download any hexadecimal file to the PIC chip. The .hex file does not have to be obtained using Mpasm.exe or Mpasmwin.exe. This project was not intended to provide a lesson in writing assembly code programs but the initial parts of the Miela.asm code, including the several lines following the Start label, can be used as a template for other program codes you may wish to write, or this code can be altered to perform other functions. However, ensure that the original of Miela.asm is preserved as a backup, to start again, if your alterations fail to run. Many books are available to provide an understanding of Assembly code writing and PIC microcontroller programming. Jaycar Electronics lists some good starters. There is also a wealth of information on the ’net: for example, do a search on “David Tait” (as mentioned previously) and you’ll find hundreds of matches! Resistor Colour Codes              No 2 29 1 1 1 6 2 4 12 2 Value 100kΩ 10kΩ 5.1kΩ 1.8kΩ 1.6kΩ 1kΩ 470Ω 330Ω 120Ω 100Ω 4-Band Code (1%) brown black yellow brown brown black orange brown green brown red brown brown grey red brown brown blue red brown brown black red brown yellow purple brown brown orange orange brown brown brown red brown brown brown black brown brown 5-Band Code (1%) brown black black orange brown brown black black red brown green brown black brown brown brown grey black brown brown brown blue black brown brown brown black black brown brown yellow purple black brown orange orange black black brown brown red black black brown brown black black black brown LIQUID CRYSTAL DISPLAY ADAPTOR Display Message sends a low signal to bit RA1 on the PIC micro, which enables the Chase portion of the program software. This switch already exists as one of the push buttons on the PIC Programmer board. Place the “Low/Hi” jumper, JP2, in This simple adaptor, to accommodate a 16-Character the Low position, close pole 2 on DipSw3 and use the second push-button x 2-Line LCD Module, can easily be assembled on a in the bank, S6, as “the switch”. piece of Veroboard. The module will run off the PIC On the PIC Programmer board Programmer and will display text programmed into diagrams, all the DIP switches on the PIC Programmer board are in numersoftware available on the SILICON CHIP website unical order which follows the PIC Micro der the title of Testbed.asm and Testbed.hex input and output sequence. This is To mount and connect the LCD Programmer and the Vero-board. You easily seen in the schematic diagram. to the Veroboard, I used a 16-pin only have to watch that you plug the The RA4 input on the micro, pin piece of machined pin header strip, IDE cable onto the headers the same 3, requires a pull-up resistor. This soldered to the LCD terminals, and way around at each end. Alternatively is also already provided on the PIC a corresponding 16-pin piece of maa suitable cable, using 34-way IDC Programmer board. Close pole 8 on chined pin IC socket strip, soldered line sockets and ribbon cable can be DipSw2, situated at the top centre of to the Veroboard. made up – not really a difficult job. the Programmer board. (This action The LCD module will then plug The 1N4004 diode is to reduce connects RA4 to the positive supply into the socket strip but requires some the amount of LCD backlighting curvia a 10KΩ resistor. Again, this is packing (cardboard or similar) as rent to a reasonable figure. Of course, easily seen on the Programmer board additional support to take the weight if you use an LCD without backlighting schematic diagram). of the LCD off the pins. the diode and other connections to Close the 8 poles on DipSw5 on The component layout diagram pins 15 and 16 can be deleted. the Programmer board to enable the (Fig.3) shows the LCD module and The trimpot is to adjust the 8 LEDs connected to port B on the mithe few necessary components, display contrast but I found that I cro, RB0 to RB7 and put a jumper on mostly links, installed on the Verorequired maximum contrast anyway, JP5. Select the Red colour for these board. which occurs when the pot is in the LEDs and the chase sequence will Install a 34-pin piece of dual-infull negative position. So this trimpot display when “the switch” is operated. line (DIL) header strip as shown on could be deleted and pin 3 of the LCD (To select the red colour, toggle the diagram, allowing space for the module bridged directly to negative. both switches, S11 and S12, on the few components between the LCD Add a trimpot later if the display is Programmer board, towards the left module and the DIL header strip. too bright. end of the board; ie to the “Red” and Note that on the diagram, the “The switch” referred to in the the “Red/Green” positions, respectracks on the Veroboard do tively.) pass completely under the LCD On the Programmer board module but have been erased all other DIP switches, not from the diagram to show the mentioned in this text, should LCD message unobstructed. be open. Although only 100mm of Download both files, menVeroboard will suffice, I sugtioned in the first paragraph, gest installing these compoand send the Testbed.hex file to nents at the right hand end of the PIC micro on the PIC Proa larger piece of board. This grammer board by the method allows other mock-ups to be explained in the texts supplied installed on the left of the 34 pin with the PIC Programmer softheader and provides the necware. essary connection to the PIC When the Run/Load switch Programmer. Alternatively, a on the PIC Programmer board reverse image can be conis placed in the run position, the structed. message * Silicon Chip * Press The easiest way to connect the switch will be displayed. between the PIC Programmer When “the switch” is pressed, and the 34-pin header on the the message will change and Veroboard is to use a comthe eight LEDs connected to puter IDE cable which will fit the PIC port B will go into a SC the 34-pin header on the PIC Fig.3: Display Adaptor layout on Veroboard. repeating chase mode. MARCH 2001  69 One-off boards for the hobbyist, prototypes, etc Yes, You Can Make PhotoResist PC Boards At Home Making your own PC boards has almost become a lost art. Last month we showed how easy it was to transfer laser-printed or photo-copied images to a blank board using an ordinary iron. While that method works, it’s not real good for fine tracks. Here’s a way to get pro quality PC boards using laser prints or copies. . . by Ross Tester P rinted circuit boards have revolutionised electronics over the past forty years or so. It’s no exaggeration to say that they make some projects possible – it would be well nigh impossible to wire up many designs involving ICs, for example, using point-to-point wiring. Just imagine a modern computer without PC boards! And they also make life easy for hobbyists. Providing you know how to solder AND you start with a clean, bright PC board, assembling a project on a PC board is arguably the most foolproof and mistake-proof method of building (even for projects which could be done other ways). even given a thickness – it is expressed as a weight of copper per square metre. 1oz (yes they still use ounces) PC boards are common, as are 2oz. But you can get 3oz and even more where a thick copper is needed. Most PC boards, especially the type you will come in contact with, have the copper on one side only. But it’s not unusual to find PC boards with What’s a PC board? Their full name, Printed Circuit Boards, gives you a fairly good clue! Once upon a time they had an even more accurate name, Printed Wiring Boards – but this name didn’t “stick” whereas PC boards did. A PC board starts life as a piece of thin fibreglass or phenolic material (and occasionally others) which is a very good insulator – as far as we are concerned, about as perfect an insulator as we can easily get. Onto this is glued a thin (no, make that very thin) sheet of pure copper. The copper is so thin it usually isn’t 70  Silicon Chip Most of what you need to make your own PC boards at home: the large packs contain pre-sensitised blank PC board (150 x 300mm sheets). In the plastic sachets are measured amounts of sodium metasilicate developer, while the plastic jar contains 600g of etchant – in this case ammonium persulphate. Not shown are the exposure box or the etching tank. (Courtesy Computronics Corp). The proof of the pudding – here’s a selection of boards, as yet uncut and undrilled, which we made using the method we’re describing here. Both SRBP and fibreglassbased material was used. Some boards are better than others: we certainly got better as we experimented with exposure times (with this resist and light source 6 - 6.5 minutes was about the best). We used “EPS” files similar to what you would download from our website, flipped them, printed them out on bond paper on our laser printer then used the images to produce the boards. Total time elapsed: about an hour! copper on both sides. In fact, many computer PC boards have many more layers – four, five, and more, with each copper layer sandwiched between a layer of fibreglass. But we’re getting a bit ahead of ourselves here. By various means, which we’ll cover in a moment, areas of the copper are removed from the board leaving “tracks” and “pads” which connect to each other. These tracks and pads form the “wiring” which connect the various circuit components together. In each of the pads and often in various places on the tracks, tiny holes are drilled right through the fibreglass and what is left of the copper. The circuit components are soldered to the copper, connecting them into circuit. Almost always on a single-sided board (ie, copper on one side only) the components are mounted through the board from the non-copper (eg fibreglass) side and their legs soldered on the copper side. If you think this is blindingly obvious, you’re perhaps a bit cleverer than the customer who some years ago sent a Musicolor kit he’d built into the Dick Smith Electronics service department, saying it was faulty. The service manager at the time (g’day Garry) commented that he’d never seen such a well constructed kit, especially the way all of the components were so neatly and carefully glued to the copper side of the board with Araldite… How are PC boards made? There are many ways to make PC boards, depending on the use, who’s making it and the number being made. However, all methods involve three main steps. Step 1: preparation Unless you’re very lucky, the blank PC board you buy (or have in your junk box) won’t be the right size. Not only must you cut the board prior to use (usually a centimetre or so larger in each direction than your finished board), most importantly you must ensure that the copper side (at least) is scrupulously clean and dry. Even though a board might look clean, it probably isn’t. It could have fingerprints on it; it could have lint and dust on it but worst of all the surface could be slightly oxidised (copper in the presence of oxygen, ie from the air, quite quickly oxidises), making other steps in the board making process difficult or impossible. Step 2: the image transfer This is usually the most difficult for the hobbyist: getting the image of the tracks and pads onto the copper. Usually, this involves some form of “resist” – a material which resists the action of the etchant, leaving the copper underneath intact. (We’ll look at etchants at shortly). Remember a moment ago we said the blank board might have fingerprints on it: the oil in fingerprints is a pretty good resist! Getting the image on is where the processes differ greatly. We’ll look at just a few: • Painting the pattern onto the blank board using a tar-based or similar waterproof “paint”. It’s messy, it’s not easy to get a good result and it’s almost impossible to produce fine tracks and inter-track spacing. • Tracing the pattern onto the board using, say, carbon paper, then going over this with a “Dalo” resist pen or similar (pens which contain resist). While easier, and capable of better results than the paintbrush method, similar problems remain. Dalo pens, by the way, are often used to repair faulty resist in other methods. • Transferring the pattern onto the board using a method such as the iron-on process described last month. This uses the carbon black and plastic binders of a laser-printed image or photocopier as the resist. The biggest difficulty here is getting consistent results. MARCH 2001  71 The difference between positive and negative: at left is a POSITIVE image of part of a PC board pattern – black tracks on white/clear background. At right is the NEGATIVE image of the same board: white/clear tracks, black background. Incidentally, you can buy material specifically intended for this process. We’ve tried them from time to time but have had little more success with them than using ordinary bond paper. • “Silk screening” the image on. This first requires the image to be photographically transferred to a silk screen and then the resist is applied by forcing it through the silk screen in contact with the copper, using a squeegee. This is the method most often used by PC board manufacturers because it lends itself to mass production. It’s not really one for the hobbyist or even commercial prototypes. • Direct photographic transfer of the image onto a photo-sensitive resist which has previously been applied to the blank board. This resist can be applied from a can or bottle, or you can buy blank PC boards which have the resist pre-applied. The latter usually give the best results. In either case, the resist must be processed in a suitable developer and dried thoroughly before etching. It is the last-mentioned method which we will be describing here. Normally, this method is used for one-offs or prototypes in industry but has been rather difficult for the home constructor due to the materials and equipment involved. Commercial users normally employ a relatively expensive photographic film positive or negative which has very high contrast, resulting in excellent results. However, it is possible to do a poor man’s version using an ordinary laser or inkjet printer. You should get perfectly acceptable results – maybe not quite as good as with film but acceptable nevertheless. Positive or negative resist Photosensitive resist can be positive-acting or negative-acting. Posi72  Silicon Chip tive-acting resists require a PC board pattern which has black where the copper tracks are and white or clear between them (ie, a “normal” looking pattern as you would see published in the magazine). Both types of resist have the image transferred by exposing them to UV light through the image while it is held tight against the resist. With positive-acting resist, the black areas stop UV light affecting the resist but the white or clear areas allow the UV light to “soften” the resist, allowing it to be “developed” away. Negative acting is the reverse: the copper tracks are white or clear and the areas between them are black. UV light hardens the exposed resist while the unexposed areas can be developed away. As a general rule, most commercial operations use negative acting resist; most hobby or one-off prototyping is done with positive acting resist. If in doubt, read the label. Step three: etching Once the required image is on the blank PC board it must be prepared for etching. Etching involves the use of chemicals which dissolve copper –they eat away at any area of the blank board not protected by resist. There are two common types of etchants used for PC boards. The first is Ferric Chloride, (FeCl2), a brown liquid (or more correctly a brown powder which dissolves in water) which has the habit of staining anything it touches! Its big advantage is that it works very well at room temperature. And for commercial users, it is a relatively easy process to extract the etched copper back out of Ferric Chloride – copper is a valuable mineral which they can sell to metal recyclers and make a few bob on the side! The other common etchant is Ammonium Persulphate ((NH4)2S208). When dissolved in water it makes a clear liquid, which is much cleaner to use than Ferric Chloride. However, it has two major disadvantages. The first is that it must be heated significantly (at least 60°C) to make it usable; the second is that because it is colourless, splashes tend not to be noticed until such time as they’re busy eating away at the kitchen sink, adjacent pots and pans, etc! Despite these two hassles, Ammonium Persulphate is by far our etchant “of choice”. Some sources suggest Hydrochloric Acid as an etchant. We have just one word for that: don’t! Step four: finishing What’s this? We said there were only three main steps. OK, we lied! One way of producing a double-sided board in perfect registration. The two sheets of film or paper are first aligned on a light box then stuck to PC board offcuts. The blank PC board to be exposed is then slid between them. Finishing off is just as important as the other steps. First, you have to drill all the holes out. Usually, we use a 0.8mm drill bit for most component holes and a 1.0mm for the larger (ie PC stakes, some semiconductors, etc) holes. You may find that some components such as on-board pots require larger holes – 2.0mm for example. And mounting holes tend to be 3.0mm. By the way, you’ll find drilling a lot easier if you use a drill stand. Even better is a small drill on a stand intended for the purpose (eg, a “Dremel”) but that might be going a bit overboard for hobbyist use! Then again, there are some hobbyists who maintain you aren’t serious if you don’t have a Dremel drill in your arsenal! But that’s not all there is to finishing off. You also need to cut the board to the right size. Commercially, this would be guillotined but you’re probably going to have to cut it slightly oversize with a hacksaw and then file it back to the correct size. And finally, there’s the little matter of getting the resist off those copper tracks. Sometimes you don’t need to – some resists are specifically designed to be able to solder through and are supposed to stay in place to protect the copper surface. Other resists must be removed with a suitable solvent (otherwise you won’t be able to solder to the board) and then once again the copper surface needs to be protected with a suitable protective coating (one which will allow soldering through). You can, by the way, make up your own “flux” coating which protects the copper surface as well as making soldering real easy: simply dissolve a few rosin crystals in a small quantity of metho and paint a thin coating onto the board. Where do you get rosin these days? We don’t know either! Double sided boards We mentioned double sided boards a while ago. These are not all that common but are still well within the scope of the hobbyist if care is taken to keep the alignment perfect (it’s called “registration” in the trade). This can be done by making a sandwich of the patterns, glued down one side to hold them in register. The double-sided sensitised board is then stuck in position to one only of the sheets as the “meat” in the sandwhich. Exposure is done as for a one-sided board but we would place some black plastic or other light-proof material against the resist on the opposite side while exposing. Some exposure systems, such as the Kinsten one shown, expose both sides at once. Another challenge for the home builder making double-sided boards is how to get the sides linked together. In commercial boards, this is done with holes that are plated through, making contact with both sides. The easiest way for the home constructor to do it is to use component lead offcuts and solder them to both sides. Likewise, where components go through holes with copper on both sides, they should be soldered on both sides. The technical name for these connections, by the way, is “vias”. (Current flows from one side to the other via the via...) Making PC boards at home (or small scale prototyping) Simple: follow the steps above! Seriously, though, folks(!) there really isn’t a great deal more to it than that. Let’s just expand on the steps above where they need expanding. “Milling” or “Routing” PC Boards We have been asked if it is possible to use an X-Y plotter or table, with the appropriate head, to mill or rout PC boards. The answer is yes, but… For a start, you need more than an X-Y table – you need the Z axis as well to be able to lift the bit clear of the board when traversing wanted sections. You also need the Z axis to raise and lower the drill(s) and cutting bits. Good X-Y-Z tables should have enough accuracy to mill a PC board. The difficulty lies in having the software capable of driving your particular table to do the job. None of these problems are insurmountable, of course, and many quality PC boards are made using this process – with nary a grain of etchant (nor any other chemicals!) in sight. A big advantage in producing PC boards this way is that very complex board shapes can be realised as well as cut-outs within the boards themselves. And a milled board will never have any undercutting or bridges (assuming the software is OK!) Some of today’s PC board design software has the capability of driving a miller or plotter instead of a printer; if it can it will generally also be able to automate the drilling (always a tedious part!). Most tables, though, will require some translation to be able to be used properly. There is yet another use for a table or plotter: using resist ink and plotting the PC pattern direct to the blank board. This is then etched in the normal way. We once did all our PC boards at SILICON CHIP this way; we gave it away for two main reasons – the difficulty in keeping plotting pens clean with this type of ink; and also because of the time it took to produce a board. Sometimes it’s cheaper for a business to get them done commercially, drilled and all: time is money! If all this is double dutch to you, we suggest you read a recent article in SILICON CHIP which reviewed a commercial PC board milling machine: “Quick Circuit 5000 PC Board Prototyping System” November 2000. An ar ticle on plotting patterns to blank boards appeared in the November 1994 issue. The Quick Circuit 5000 PC Board Prototyping System mills boards instead of etching them. It’s capable of cutting a variety of shapes as well as milling the unwanted copper away. It’s not real cheap, though! MARCH 2001  73 (1) Cleaning the blank board (2) The resist (3) Your PC pattern As we said before, your blank PC board needs to be cut about 1cm or so larger than the finished board in each direction. You should also file off the edges to make sure there are no bits of copper poking up. Of course, if you are using pre-sensitised board it comes already clean as well as coated. So you can skip straight to step 3! There are a couple of conflicting aims in cleaning. One is that you need to have the copper clean – very clean – but you don’t want to scratch deep gouges in the copper surface. That would appear to rule out steel wool (in fact, the text books say so!) but to be honest, we’ve used steel wool on badly oxidised boards and achieved perfect results. Normally, though, we’d use something like powdered “Ajax” and a new, non-metallic scouring pad. You shouldn’t use the old scouring pad from under the sink because invariably it will have bits of grease and grime trapped in it, which could be transferred to the copper surface. When you are sure the copper surface is very clean, give it a good rinse under fast-flowing water and then stand the board vertically in the sun to dry. Don’t wipe it clean because this could leave lint or fibres on the surface. Have a good look at the board (even use a magnifying glass) to make sure there is nothing on it, then protect it from dust. Having just gone through all that, there is a way which you can avoid all of the above steps and hassles (and some of the next!) and that is to use a pre-sensitised blank PC board. These are available from a number of suppliers – those shown are “Kinsten” brand boards (from Computronics, 08 9470 1177). Another popular brand is “Riston”. If you use the pre-sensitised boards, all this is done for you. You simply have to cut the board to the required size under subdued (ie, normal household) light. Sunlight is a no-no. Once you open the light-tight packaging, avoid unnecessary exposure for the remainder of the boards in the pack and also for the board you are handling. A couple of minutes, a couple of metres away from a fluoro light won’t worry it too much; much longer or closer you will risk “fogging” the resist and therefore making it useless. If you must apply your own resist to blank boards, first make sure the resist you are using is positive acting (otherwise you’ll end up with the reverse of what you want). Photo-resists are commonly available in either liquid or spray-on form. In both cases, the idea is to get a nice, even coating on the copper surface, not too thick and not too thin. Apply with a “swirling” motion to move the resist around and into missed areas. While resist is fairly liquid, it starts going thicker fairly quickly so you need to work reasonably fast. Most spray or liquid resists do not dry hard enough naturally and must be baked in a just-warm oven/frypan. Follow the instructions carefully when baking – and remember that as it dries the resist becomes more and more light sensitive (that light in the oven?). Once your resist-coated board has dried properly, it’s much like the pre-sensitised ones (including handling and light sensitivity). As you probably know, as well as being published in the magazine, most PC board patterns for SILICON CHIP projects are available from the website (www.siliconchip.com.au). Download these and you can make your own PC boards. However, there is a choice when it comes to printing out the pattern. You can usually achieve a more-than acceptable result by printing the pattern on plain bond paper (ie, photocopier paper). People who use plain paper report “10 thou” tracks (small enough to fit between IC pins) are no problem. But you will probably achieve a better result by using clear film, as used for an overhead projector. First, plain paper: you need two things: one is a very good quality print with absolutely black blacks. Most modern day laser or inkjet printers will achieve this for you. The other, and most important, is you need a reverse direction, or “mirror image” print – that is, any writing is back to front when you look at it. The reason for this is simple: you want the black image in intimate contact with the resist so that the light which exposes it doesn’t have to then pass through the paper. Otherwise light scatter occurs in the paper which results in a much inferior result. Most printer drivers have the facility for printing a reverse direction, “mirror” image. (Note that you don’t want a “negative” image – that reverses whites and blacks). Ensure also that the size is right – PC board sizes are given in the project parts lists for this reason. Hey, we’ve seen boards made 200% or 50% of original size. They look good but gee the components are hard to fit! At far left is the laborious task of cleaning blank PC board. It’s important to remove all gunk and oxidation prior to coating with resist. Both cleaning and coating are already done when you use presensitised board such as this “Kinsten” brand board from Computronics. It’s available in a wide range of board and copper thicknesses. We’d take that “less than 10 minutes” claim with a chunk of salt, but! 74  Silicon Chip (4) Exposing the board Finally, if you have a choice of paper, print on the lightest weight which gives good, consistent blacks. Now to the alternative, film: most laser printers and inkjet printers can print to film, as you would use for an overhead projector. Unfortunately, though, the density (or “blackness”) of most isn’t quite good enough for PC board making. (Hold one up to the light and you’ll see what we mean). This can be easily overcome by printing two copies, then very accurately aligning them and sticking them together. You will see the difference when you hold this up to the light! As with paper, print the film reverse direction so that the bottom layer of film will be in intimate contact with the resist. And before use, check the size one more time. Any flaws in the printed image (paper or film) can be retouched with a fine felt-tip pen. This includes breaks in tracks, pinholes, etc. We ’ v e b e e n t a l k i n g a b o u t down-loading and printing PC board patterns – but if you can get a good quality photocopy from the patterns published in the magazine, these too can be used. The major problem you’re going to have is that few photocopiers have the ability to print reverse or “mirror image”. If you must have the ultimate quality, download the PC board “EPS” file from the website and take it to your local DTP service bureau, who should be able to output the file on high-contrast film for you for a few dollars. Tell them you want a film positive, right reading, emulsion side down. This puts the PC board image right next to the resist when you expose it – that is, no layer of film in between. Here’s where you might have to use some ingenuity. The aim is to have that black image of the PC pattern in intimate contact with the resist. Commercial organisations doing a lot of prototypes should invest in an exposure box, such as the Kinsten KVB-30D shown here. Once again, this comes from Computronics. It really is the “Rolls Royce” and has everything you need for great boards: a vacuum pump to ensure the pattern is held tight against the board, a digital timer and even upper and lower UV lights so you can do two sides at once (on double sided boards). All this comes at a price, of course: you won’t see any change from $700 when you This automatic UV exposure unit from Computronics would have to be the ultimate: vacuum include GST! pump, digital timer, capable of double sided So what does a hobbyist do? boards in one exposure . . . but the price tag You have two problems to puts it a tad out of the reach of the hobbyist. overcome. The first is to ensure that intimate contact we talked signed to emit UV and while most is about before; the second is the light converted to visible light by the phossource. phors, enough “escapes” to be usable. The first problem can be solved It is possible to buy special UV as simply as placing the board and fluorescent tubes which glow pale pattern between two sheets of glass, blue (similar tubes are in the Kinsten held together by large bulldog clips. exposure unit). These are available Alternatively, you can buy small exin 20 & 40W sizes to fit standard 2ft posure frames at art and silk screen & 4ft fluoro fittings. However, these suppliers (or you could make one). aren’t recommended for domestic use Just remember, the thicker the glass, because the UV they emit could be the more opaque it is to UV light. harmful to the eyes and skin at close The second problem also has an easy range. And they’re not real cheap! solution – in fact, two easy solutions. Just remember before exposing If it’s a fine day, you could use that big pre-sensitised board to remove the bright yellow thing up in the sky – it backing paper! emits tons of UV light along with visible light (which won’t matter). Exposure times Or you could use ordinary houseNeedless to say, exposure time hold fluorescent tubes. They are devaries enormously according to your light source and your PC pattern type. As an example, even for the Kinsten A high contrast unit recommended exposure varies laser print on bond paper (ie, from 60 to 90 seconds using high qualvery black blacks ity film (ie, very black blacks and clear and nothing in the whites) to five minutes or more using whites) is OK when a laser print on plain paper. you can’t get (or afThere is only one way to determine ford) a photo-graphthe exposure for your setup: experiic film positive. You ment with small pieces of PC board. can get very good And the only sure way to determine results from laser success or failure is to follow the next and inkjet prints. step and develop the image. MARCH 2001  75 (5) Development Developers vary according to the type of resist and also their source. For the Kinsten presensitised PC board, the developer is sodium metasilicate. We’ve also used resists that develop in a weak solution of caustic soda (sodium hydroxide). Some developers are simply labelled “developer” with no hint as to what is in them (which is probably illegal these days). Prepare the developer as per the instructions packed with it. If it is a powder or crystal type, you need to ensure that it is totally dissolved before use. Whatever the type, always use plastic gloves when preparing and using developer. Most are caustic or alkaline and can do wondrous things to your skin. Also use plastic developing trays and implements for the same reason. A pair of plastic tongs is handy. Another useful tool we’ve found is a plastic fork, á lá the local Chinese take-away. To develop the board, place it pattern-side-up in the developer and gently rock the tray to give a slight sloshing motion. You should start to see the pattern emerging after just a few seconds (depending on resist and developer) and then the developer start to lift off the exposed areas of the board within about 30 to 60 seconds. Soon, all of the exposed areas should be free of resist. Most resists will develop fully between about 30 seconds and two minutes. Less than this, the developer is probably too strong and is likely to start attacking the wanted tracks. (7) Etching Longer than this and the developer may never do its job in clearing off the unexposed resist. Developing is normally done at room temperature. Higher temperatures will result in shorter times but again, may make the developer too active. Each pack of developer will handle a number of boards. Most instructions say to mix up a fresh batch of developer for each batch of boards being done as it will only last a day or so. We’ve found that some developers, especially those based on caustic soda, will last for weeks or months. And if they lose their punch, we just throw in another couple of flakes of caustic soda! OK, so it’s not technically correct. But it works for us – and saves us having to buy developer all the time! If the solution is really badly discoloured, that’s when we make up a fresh brew. (6) Drying or “post-baking” Some resists are fairly soft and require “post-baking” (ie, baking after development) to ensure they are hard enough to withstand the rigours of etching – particularly when using hot etchant (ammonuim persulphate). This step applies more to the sprayon or pour-on photo resists. We generally place the board in a just-warm oven or frypan (and we mean just!) for an hour or so after development. Post-baking is not necessary for the Kinsten resist – as soon as it’s developed and rinsed, it’s ready for etching. Developing is done in a shallow tray. Keep rocking the tray to ensure the board is continually being agitated. This board is almost developed. The dark patches on this PC board are where we tried to repair a positive before exposure: the ink attacked the resist! 76  Silicon Chip We’ve already mentioned the common etchants. Simply mix them up according to the directions in a plastic (not metal!) container. We always mix ammonium persulphate with hot water (close to boiling point) to make sure it’s hot enough to use when etching. But be careful – both with the hot water and then with etchant splashes. Ammonium persulphate is supposed to be mixed at about 200g per litre of water – we usually use about a cupfull to the litre. Near enough is close enough! Back in the good old days, a common mix for ferric chloride was “a pound a pint” – probably way too much but it was easy to remember! Again, keep in mind that etchants will attack most metals. As far as etching methods and equipment are concerned, there are also a couple of different routes you can follow here. If you’re only going to do the occasional board, a largeish, flat, heavy-duty plastic tray will suffice. The type used by photographers is ideal. The board sits in this tray pattern-side-up and you rock the tray back and forth to get a wave action moving the etchant over the board. It usually only takes ten minutes or so to etch a reasonable size board this way. Even better is to have two trays, one of which “floats” in the other containing hot water, keeping the etchant warm in the second tray. If you’re going to do a number of boards, it will pay you to invest in an etching tank. They’re fast, convenient and produce less mess. You can use the same tray to etch a PC board. This one is well advanced with blank board appearing at the top. Use a “sloshing” motion to keep the hot etchant moving over the board. It’s a lot slower than using the etching unit shown above right . . . but it’s also a lot cheaper! This etching tank contains a heater and air blower, both of which speed up etching times significantly. Boards hang vertically from the clips visible at the top. Most etching tanks, at least for smallscale use, are similar to the type shown, the Kinsten ET-10 from Computronics. It is a clear or near-clear plastic thin vertical “box on legs”. The idea is for the board to hang vertically in the tank so that, as the etchant eats away at the copper, it can fall away from the surface, allowing the etchant to keep doing its work on the copper underneath. There are a couple of things which will speed up etching. We’ve already mentioned heat: it’s one thing to mix the etchant with hot water at the start but it’s another to keep it warm. One option for this type of etching tank is a submersible heater, preset to keep the etchant at about 60°C or so. It looks for all the world like a tropical fish aquarium heater – probably because it is, just set a bit higher than normal (tropical fish in 60°C water become tropical floaters!). The other item to speed up etching is an air pump, designed to bubble air through the etchant along the PC board surface. This dislodges copper particles much more quickly than hanging or even agitation. Dare we say this pump looks for all the world like a fish tank air pump? To use the etching tank fill the tank with warm (not excessively hot) etchant. You need to avoid thermal shock on the heater glass. Turn on the heater until the pilot light goes out – the etchant is then at the required temperature. Hang the PC board in the etchant using the clips supplied (vary the height of the clips if necessary) and turn on the air agitation. The air pump should always be placed higher than the tank to avoid syphoning etchant into the air pump. Etching should take somewhere between about 3 and 10 minutes, depending on (a) the size of the board, (b) the amount of copper being removed, (c) the strength of the etchant and (d) the temperature of the etchant. It is complete when all the unwanted copper is removed – but be careful not to over-etch because some of the wanted copper may be either undercut (where the etchant starts attacking the tracks from the sides after removing the unwanted copper) or in some cases, completely destroyed. If your PC boards consistently have etched scratch marks, it probably means you were too vicious with the cleaning process and the etchant has found very thin copper to eat away. If it has numerous pinholes, your exposure time is too long OR your PC board pattern doesn’t have enough blacks. Make sure you empty the etching tank and rinse it out – otherwise you’ll find crystals forming in the bottom. (If you use ammonium persulphate etchant, it will crystallise out to copper sulphate). (8) Finishing Off If the instructions for your resist say that it can be soldered through, leave it in place. It will prevent oxidation of the copper. However, many resists must be removed – the usual solvents for these are alcohol (methylated spirit) or acetone. If you do remove the resist you should coat the board with a solderable lacquer or flux (see above). The only remaining tasks are to drill the board and cut it to size – again, we covered these areas above. Contact: Computronics Corp Pty Ltd 8 Sarich Way, Bentley WA 6102 Tel: (08) 9470 1177; Fax (08) 9470 2844 Website: www.computronics.com.au PC Board soldering tips While on the subject of making PC boards, perhaps a word or two about soldering PC boards would be in order. 99.9% of problems with kits are in the soldering of components, especially to PC boards. The biggest mistake constructors make is using a soldering iron which is too small for the job. A 10 or 15W iron used to be a popular choice by many, believing that it would minimise the risk of heat damage to semiconductors and other sensitive components. Believe it or not, it’s not necessarily so – in fact, it can be the exact opposite! Because the light iron cannot supply sufficient heat and because the copper of the tracks is such a good conductor of heat (taking heat away from the joint) invariably you have to leave the iron on the joint much longer – maximising the risk of damage! For the hobbyist, a much better choice is a 20-25W iron, either mains-powered or (preferably) low voltage, with a fine tip kept in bright, shiny condition. The best choice is a temperature-controlled iron or soldering station, where the iron is usually rated much higher (perhaps 60-70W) but only supplies the heat “dialled up”. Be careful not to use a temperature-controlled iron at too high a temperature. A bad choice is any heavy-duty iron because these are made to supply a lot of heat and can do a lot of damage to fine copper PC board tracks. Except in case of emergencies, you shouldn’t use a gas-powered iron to solder to PC boards – they too can develop far too much heat and they can be hard to control. Finally, always use solder intended for electronics work. Don’t buy solder from the local hardware store – you’ll probably end up with plumbing solder which contains a corrosive flux (it can eat through the thin copper tracks sometimes within weeks). Multicore electronics solder, preferably of a thin rather than thick gauge, is the way to go. That’s what you would normally be supplied in electronics kits. If in doubt as to which solder to buy, ask at your usual electronics dealer. SC MARCH 2001  77 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au More fun with comparators This month we try stacking two comparators to make a “window” comparator, a very commonly used circuit in all sorts of control applications. We generate an “input” signal using a potentiometer fed from DC and demonstrate how the window compara­tor responds to a varying DC signal. Pt.5 By LEO SIMPSON OK; what’s a “window” comparator? We’ve had a look at two variations of standard comparator circuits in the December 2000 issue and saw how they switch their outputs when the input goes above or below a reference voltage. Typically, a comparator’s output might be made to switch high when its input goes above +6V and a circuit for this is shown in Fig.1 on p75 of the December 2000 issue. As it happens, there were two comparator-based circuits in last month’s issue. Firstly, the Li’l Pulser train controller is based on two comparators connected to generate a PWM (pulse width modulated) waveform and secondly, the Bass Blazer frequency display has a whole bunch of comparators driving LEDs in four columnar arrays. There is no reason why you could not hook up the key parts on these circuits on your Protoboard and then, if you have an oscilloscope, see if you can duplicate the example wave­forms. Back to “window” comparators: say we wanted to produce a comparator circuit which would indicate when an input was above +6V and below +9V; ie, within a 3V range. We would need two comparators, one inverting and one non-inverting and they could be hooked up as shown in Fig.1. Notice that each comparator drives its own LED and that each comparator has its reference voltage derived from the same string of three resistors; after all, why have two voltage divider strings when we can do it with one? So pin 5 The circuit is fairly simple and should only take you about 10 minutes to wire up. The pot at far right is not used in this circuit. is connected to a (nominal) reference of +6V and pin 2 is connected to +9V. We also derive the input voltage from the same potentiome­ter, VR1, and as we wind the pot up and down, the LEDs will tell the story. The Protoboard layout for Fig.1 is shown in Fig.2. When we wind up VR1 so pin 6 of IC1b is above +6V, LED2 lights. And when pin 3 of IC1a is below +9V, LED1 lights. What we find is that when the input from VR1 is between +6V and +9V, both LEDs will be alight – this is the condition we wanted to detect. Furthermore, when pin 3 of IC1a is above +9V, LED1 will be off but LED2 will be on, because pin 6 of IC1b will be above pin 5. And when pin 6 of IC1b is below pin 5 (ie, below +6V), LED2 will be off and LED1 will be on. So we see that the two comparators together give an indica­ tion when an input voltage is above +6V and below +9V (both LEDs on) but it is a bit “mickey mouse”: both LEDs need to be on to indicate the wanted condition and if just LED1 or LED2 is on, then the wanted condition is not there. What we really need is a combination circuit which will drive just one LED to indicate the wanted condition where the input voltage is within the range of +6V and +9V. MARCH 2001  81 Fig.1: both of these comparators drives its own LED and each comparator has its reference voltage (9V or 6V) derived from the same string of three resistors. The input voltage for both comparators comes from the same potentiometer, VR1. Let’s try the new circuit of Fig.3. It still uses two com­parators, one inverting and one non-inverting, but now they both have their outputs joined directly together and they just drive the one LED. Normally, connecting the outputs of two op amps together would cause serious problems but we are using compara­tors with “open collector” outputs which require a pullup resis­tor. Open collector outputs In reality, an “open collector” output is an NPN transistor with its collector connected to the output pin, as shown in Fig.4 which is the sim- plified schematic for one comparator in an LM393. Because nothing is connected to this collector, we say it is “open collector” (as in open-circuit). For the transistor to work, it must have a “pullup” resistor to the positive supply rail (in this case +12V). When the transistor is “off”, the pullup resistor “pulls” the output high. And naturally, when the transistor is “on”, the output will be pulled low. Now the point about comparators with open collector outputs is that you can connect two or more comparator outputs in paral­lel without any chance of damage and they can all drive a common load. Even more to the point, if one comparator output is on and all the others are off, the common output is still low. Some designers like to think of this as an OR gate function whereby all the comparator outputs are ORed together. Personally, I don’t think this helps in understanding the principle. It is quite simple – they’re all in parallel and if one switches low, the common output is low and that is that; it doesn’t matter what the other comparators do. By the way, in some data books you will see “open collec­tor” outputs referred to as “uncommitted”. It means the same thing. The other point of difference between Fig.3 and the first circuit of Fig.1 is that we have swapped both sets of comparator inputs. If they’re not swapped, you will find that the single LED stays on all the time. If you think about the circuit of Fig.1, where at least one LED is on all the time, then it stands to reason that if we now use a common LED it will be on all the time; hence the need to swap the comparator inputs. Oh and there is one other difference between the circuits of Fig.1 & Fig.3. In the latter diagram we have substituted “real world” values of 4.7kΩ for the 5kΩ resistors and these change the reference voltages slightly. So now what happens as we vary VR1? This will swing the input voltage to the two comparators over almost the full supply range. When the input voltage is at its lowest (ie, with Fig.2: use this diagram to wire up the circuit of Fig.1. Winding VR1 up and down will cause the LEDs to light independently. 82  Silicon Chip Truscott’s •RESELLER FOR MAJOR KIT RETAILERS •PROTOTYPING EQUIPMENT •COMPLETE CB RADIO SUPPLY HOUSE •TV ANTENNA ON SPECIAL (DIGITAL READY) •LARGE RANGE OF ELECTRONIC COMPONENTS Professional Mail Order Service Fig.3: this circuit is similar to Fig.1, using two comparators, one inverting and one non-inverting, but now they both have their outputs joined directly together and they just drive the one LED. This is permissible because they have “open collector” outputs. VR1 set for maximum resistance), pins 2 & 5 will be at around +2V; ie, well below the reference voltages for both comparators. As a result, IC1a’s output will be high (ie, off) and IC1b’s output will be low (on). Therefore LED1 will light. When the input voltage from VR1 is between +6V and +9V (say +7.5V) both outputs (of IC1a and IC1b) will be high and the LED will be off. And when the input from VR1 is above +9V, IC1a will be low (on) and IC1b will be high (off), so LED1 will be on again. Wrong result But this is exactly the reverse result to what we wanted! We wanted LED1 to light only when the input voltage from VR1 was between +6V and +9V. What to do? The easy approach would be to use another comparator to invert the common outputs of IC1a & ICb and that is what you often see when a window comparator is called for – the design uses three comparators. But there is a simpler way. Merely by moving LED1 so that it is now between the commoned pins 1 & 7 and 0V, as shown in red on Fig.3, we get the right result. LED1 now lights for input voltages between +6V and +9V. So that’s the window comparator: two comparators driving a common LED to indicate inputs between two SC separate voltage thresholds. Fig.4: this is the simplified schematic for one comparator in an LM393. It shows the output as an “open collector” NPN transistor (Q8). This requires a pullup resistor for the NPN transistor to work. (National Semicon­ ductor Linear Data Book). Truscott’s Amidon Stockist ELECTRONIC WORLD Pty Ltd ACN 069 935 397 Ph (03) 9723 3860 Fax (03) 9725 9443 27 The Mall, South Croydon, Vic 3136 (Melway Map 50 G7) email: truscott<at>acepia.net.au www.electronicworld.aus.as P.C.B. Makers ! • • • If you need: P.C.B. High Speed Drill 3M Scotchmark Laser Labels P.C.B. Material – Negative or Positive acting • Light Box – Single or Double Sided – Large or Small • • Etch Tank – Bubble • • Prompt and Economical Delivery Electronic Components and Equipment for TAFEs, Colleges and Schools FREE ADVICE ON ANY OF OUR PRODUCTS FROM DEDICATED PEOPLE WITH HANDS-ON EXPERIENCE We now stock Hawera Carbide Tool Bits KALEX 40 Wallis Ave E. Ivanhoe 3079 Ph (03) 9497 3422 FAX (03) 9499 2381 ALL MAJOR CREDIT CARDS ACCEPTED MARCH 2001  83 More-MIDI A low-cost MIDI expander box Want to drive more synthesisers or instruments from your MIDI sequencer or computer sound card and MIDI-Mate combo? Here’s a simple little expander box that takes one MIDI signal and lets you feed it to four instrument inputs. It’s low in cost and can be assembled in just an hour or two. By JIM ROWE I F YOU’RE REALLY INTO electronic music, odds are that you now have quite an array of synthesisers, MIDI instruments, se­quencers, keyboards and other controllers. And that probably means swags of MIDI cables, daisy-chaining around from this box to that box to the other box, and so on. 84  Silicon Chip That’s OK, but daisy-chaining introduces cumulative delays into the MIDI system and sooner or later those delays can become audible and irritating. The simplest solution is an expander box like More-MIDI. It “pumps up” the number of MIDI outputs from your sequencer or com­puter and lets you run more signals directly out to the instru­ ments, in “star” fashion. You still need just as many cables but at least the instruments are all driven with just one short delay – ie, the minuscule 5µs or so introduced by the circuitry in More-MIDI itself. That’s really not significant in MIDI terms. Best of all, More-MIDI is cheap and very easy to build. It uses just three low-cost ICs plus a handful of passive components and literally everything mounts on a small PC board which fits in a compact low-profile instrument case. Power comes from a stan­dard 9-12V DC plugpack. Circuit description Fig.1 shows the circuit diagram and, as you can see, More­-MIDI is very straightforward in electronic terms. It’s basically just a MIDI input stage, Fig.1: the circuit uses OPTO1 to isolate the input stage plus a 74HC04 hex inverter (IC1) to drive the four output stages and the signal indicator LED. buffered correctly using the usual optocoupler, which then drives four identical MIDI output stages. The input stage is based on OPTO1, a 6N138 fast optocou­ pler. A 220Ω series resistor sets the correct current level through the optocoupler’s input LED, while the 1N4148 diode protects it from possible damage due to reversed-polarity inputs. Don’t be tempt­ed to substitute another optocoupler for the 6N138, by the way. Its speed is necessary for handling MIDI signals correctly. The output from IC1 (at pin 6) is effectively an inverted version of the incoming MIDI logic signal and inverter IC2f (74HC04) is used to restore its polarity. The output from IC2f is then used to drive the four MIDI output stages via inverters IC2a, IC2b, IC2d & IC2e. As you can see, each of these drives one of the four MIDI outputs, with a pair of 220Ω series resistors to set the correct 5mA output current level in each case. The sixth and final inverter inside IC2 is used to drive indicator LED1, so that it blinks to show when MIDI signals are passing through More-MI- DI. This sort of indication can be very handy when you are trying to sort out cable problems! Power supply Power for More-MIDI’s circuitry can come from any convenient source of 9-12V DC, such as a small plugpack supply. The current drain is less than 50mA, allowing the use of a simple voltage regulator system based on IC3 – a standard 7805 3-terminal regu­lator. A 78L05 in the smaller TO92 case could be used if you prefer, although they’re not much cheaper. Diode D1 (1N4004) is connected in series with the DC input to prevent damage to the 7805 or 220µF input filter capaci­ tor in the event of the polarity being accidentally re­versed. Construction Assembling More-MIDI is very easy, as everything fits on a PC board. This measures 117 x 112mm and is coded 01103011. As you can see from the internal photo and parts layout diagram (Fig.2), even the DIN sockets and power connector mount directly on the board, so there’s no off-board wiring at all. There are no wire links on the board itself, either. After checking the board for possible solder bridges and other defects, begin the assembly by fitting the five DIN sockets, as these can be a little tricky. Once fitted, all seven of their mounting pins should be soldered to the board pads, to make sure each one is solidly attached. You might like to fit the 2.5mm DC input connector at the same time, as this too can be a bit fiddly. Ideally, the board should be provided with small slots for its 3mm-wide mounting lugs but if not, you can elongate the holes with a jeweller’s rat-tail file or fine holesaw. The resistors and capacitors can be fitted next, taking care with the polarity of the two electrolytics. After that, you can fit the diodes, ICs and LED. These also need to be fitted with the correct orientation, as shown in the board diagram. Note that the LED is fitted with the flat side of the collar on its plastic body towards CON4, while the longer anode lead goes towards CON5. Before mounting it, bend its leads down at right angles about 6mm from the bottom of the body so that it faces forwards correctly. The leads are solMARCH 2001  85 Parts List 1 PC board, code 01103011, 117 x 112mm 1 low-profile instrument case, 141 x 111 x 35mm 5 5-pin DIN sockets, 90° PCmount 1 2.5mm PC-mount DC power connector 1 10mm x M3 machine screw with M3 nut 4 small self-tapping screws, 6mm long Semiconductors 1 6N138 fast optocoupler (OPTO1) 1 74HC04 hex CMOS inverter (IC1) 1 7805 5V regulator (REG1) 1 3mm red LED (LED1) 1 1N4004 1A diode (D1) 1 1N4148 or 1N914 switching diode (D2) Fig.2: follow this parts layout diagram to build the PC board. Capacitors 1 220µF 25VW PC-mount electrolytic 1 100µF 16VW PC-mount electrolytic 1 0.1µF monolithic Resistors (0.25W 1%) 9 220Ω 2 330Ω around” and also provides a tiny amount of heatsinking. The heat­ sinking is not really needed here but it sure doesn’t do any harm. Final assembly Fig.3: check your PC board against this full-size etching pattern. dered to the board pads so the body axis is about 11mm above the top of the board, ready to line up with the corresponding hole in the front panel. 86  Silicon Chip If you wish, the voltage regulator IC3 can be secured to the PC board using an M3 screw and nut, as in the prototype. This stops it “flapping Once the board is completed, it’s mounted inside the case using four small self-tapping screws (6mm long), which mate with some of the pillars moulded into the bottom half of the case. If you don’t have pre-punched front and rear panels, you can drill (or punch) the required holes using photocopies of the front and rear panels as templates. The hole for the LED is a whisker over 3mm diameter; that for the DC input connector is 8mm dia­meter; and those for the DIN sockets are 15mm or 16mm in diameter. On the prototype, the latter were punched using a 16mm screwtype hole punch, after first drilling suitable guide holes and enlarging them as required with a hand reamer. The labels can now be affixed to All the parts, including the MIDI sockets and the DC power socket, are mounted on the PC board, so there is no internal wiring to be done. Make sure that all polarised parts are correctly orientated. the panels, after which they can be slid into the case slots and the LED pushed through its matching hole in the front panel. Finally, the lid can be fitted to the base and secured using the two screws provided. Getting it going There are no setting-up or other adjustments for More-MIDI and it should work correctly as soon as you apply DC power. Note that the LED will only glow when MIDI signals are actually pass­ing through the unit – after all, it’s an activity indicator rather than a pilot light. What if More-MIDI doesn’t work? Well, there’s only a small number of possible reasons for this, so it shouldn’t take long to track down the cause of the problem. For example, you might have fitted the input protection diode (D1) incorrectly, which will stop the circuit from working at all. Check the +5V rail to confirm that everything is OK here. Another possibility is that one of the two electrolytic capacitors is the wrong way around and drawing Fig.4: these full-size panel artworks can be used as drilling templates. heavy leakage current. Alternatively, you might have IC1 or IC2 around the wrong way, which would again prevent normal operation. If all these things check out correctly, perhaps you have the 1N4148 diode (D2) around the wrong way. This would effective­ly “short circuit” the MIDI input, preventing the input signal from getting any further. Finally, there’s one more possible error. If the circuit does seem to be working in terms of distributing MIDI signals but the LED stubbornly refuses to blink, guess what? You’ve almost certainly fitted the LED itself around the wrong way! But if you haven’t made any of these mistakes, congratula­tions. Your More-MIDI should spring to life and be ready to expand your MIDI capaSC bilities. Happy music making! MARCH 2001  87 VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG Elegance from the 1920s : the 1929 AWA C58 Radiogram In the early days of radio, receivers varied from simple crystal sets built into packing case timber cabinets to very elaborate multi-valve receivers installed in ornate (and expen­sive) cabinets. This month, we look at a set from the upper end of the price range – the AWA C58 radiogram circa 1929. In the main, crystal sets were built or purchased by fa­milies with little spare cash. Conversely, receivers at the other end of the spectrum were purchased by the wealthy to grace the lounge or smoking room in their mansions. In many cases, it was very much an ego trip to have an expensive radio, proving that “I’ve got more money than you”. Anyone with a very healthy bank balance back in 1929 could have bought an AWA C58 radiogram. To say that it was impressive is an understatement – the cabinet measures an ample 1270mm high x 813mm wide and is 458mm deep. And commensurate with its impos­ing look, it requires two muscular people to lift it! Housed beneath the lift-up lid at the top of the cabinet is a single-speed 78rpm record player. It uses a “one play” steel needle (stylus) and the usual enormously heavy pick-up head, with a stylus weight of 125 grams. The owner of the unit featured here is restoring both the turntable and the pickup head. Below the turntable is a shelf which carries the radio frequency (RF) stages, along with the detector and first audio stage of the receiver. The front part of the chassis is metal and carries the tuning capacitors and an audio transformer. A pheno­lic sheet at the rear of the metal chassis carries seven valve sockets, the RF coils and a few RF bypass capacitors. The wiring is all point-to-point and the terminals/sockets for each valve are riveted directly to the phenolic sheet, so there are no separate valve sockets. Instead, they are all part of an “integrated circuit board”. The bottom shelf of the unit carries a large power supply and the push-pull 245 audio output valves which drive the loud­speaker. This section is built This view shows the rear of the top chassis which carries the RF stages and the push-pull audio driver stage. 88  Silicon Chip This is the RF chassis from the front. The tuning capacitors are all single gang and are coupled together using brass bands and pulleys. on a very substantial metal chas­sis of the type that became almost universal from the early 30s onwards. An unusual feature here is that the metal chassis is shielded underneath by a metal plate attached to the wooden shelf. It becomes operational when the chassis is screwed into the cabinet. In fact, shielding is common in this section of the receiver. One shielded enclosure uses no less than eight paper block capacitors as filter and bypass elements. The leads come out of the block and radiate around the chassis to do their respective jobs. Another enclosure contains a 4-section filter choke which feeds various sections of the set. The field coil is, of course, separate. The power transformer that’s now in the set is not shielded but the original one apparently was, as mounting holes are evi­dent. It is necessary to be careful here, as there are exposed terminals on this transformer. Unfortunately, it is just too wide to slip a shield over it. Dismantling the C58 Before applying power to any elderly set that is to be restored, I first dismantle it and check it thoroughly. I never apply power to such old sets until they are checked, as the damage can be devastating if a serious fault is lurking in the works. Dismantling the receiver is an involved task. First, all 15 leads have to be removed from the terminal block at the back of the power supply and audio output chassis (with power off and disconnected from mains). The power supply lead and the field coil The cabinet is big, ornate and impressive. It features two “bat-wing” doors which swing open at the front to reveal the controls and loudspeaker grille. MARCH 2001  89 At last it was all spread out on the work bench. I do not rush restoration jobs where such old and obviously valuable equipment is involved. Where would I get a replacement UX245 or UX226 from? This set has such valves and some of the slightly later versions (245 and 226). Tracing the circuit This is the power supply & audio output chassis. The two audio output valves (2 x UX245) operate in push-pull configuration. The electrolytic capacitors in the power supply and audio output chassis were all replaced with modern equivalents. leads are then removed, after which the mounting screws can be removed and the chassis lifted out. Next, the record player shield must be removed, as it prev­ents access to the top chassis. The front panel knobs are then removed, followed by several screws from under the shelf to free the chassis. It was necessary to move the chassis around so that the large cable from the main chassis could be drawn back through a hole in the shelf. Additionally, there is a 6-terminal block on this chassis and the leads from this block were released. By then manoeuvring the chassis around and sliding my hand in front of the chassis, it was possible to determine which front 90  Silicon Chip panel toggle switch was attached to a group of three leads. The toggle switch was subsequently removed from the front panel and this at last allowed the chassis to be removed. The cable that was removed from the 6-terminal block was connected to several other bits and pieces, namely a capaci­tor, a choke, a “strange” tapped switch fitted with resistors as a volume control, and a switch to select between radio or gramo­phone operation. This latter switch is similar to those used in early telephone exchanges. Finally, the leads to the pick-up head were also removed so that this assembly could be removed, albeit with some difficulty. Receivers of this era did not come complete with circuit diagrams and this set is no exception. As a result, I methodical­ly traced out all the bits and pieces on the metal chassis and noted where each component went. In particular, I noted what went to each of the lugs on the 15-terminal strip. Despite the set’s age (70+ years), very little had been replaced. I counted two high-voltage filter capacitors, the power transformer, a few valves, some wiring changes around the big metal boxes and a few alterations around the loudspeaker. There was no evidence of any work having been done on the RF, detector and audio chassis, except for some early valve replacement. The little subgroup of parts, including the radio/gram switch, were a bit the worse for wear and were either re-terminated or replaced. Only a couple of perished wires needed replacement on the two major chassis. I traced out the circuit as best I could. The large metal boxes had many unidentified leads coming out of them. The condi­tion of the internal components was an unknown quantity and only an educated guess could initially be made as to what was inside some of them. However, I was able to correct the inaccuracies when power was applied to the set later on. It was interesting to note that all the filament to earth bias resistors for the RF chassis were actually on the power supply chassis and that some of the leads were nearly a metre long. Fortunately, the most critical bypass capacitors were on the RF chassis itself. Power supply checks I tested the power transformer and the filter chokes for any breakdown in the insulation which could cause short circuits or short the mains to the chassis. This was to make sure that there would be no problems for the set or electrical shocks for me or the owner. I did this using a high-voltage MARCH 2001  91 The valve sockets and RF coils in the RF, detector and first audio stages are mounted on a phenolic sheet attached to the rear of the metal chassis. The metal (front) part of the chassis carries the tuning capacitors and an audio transformer. tester that can apply 500V or 1000V to a component under test. SILICON CHIP described a more versatile model than mine in May 1996. Note that conventional ohmmeters can give a false sense of security here since they test at low voltage only, whereas faults such as insulation breakdown sometimes only show up when high-tension (HT) voltages are applied to the set. Ohmmeters often use a 1.5V battery to do these tests but the actual item being tested may have insulation designed to withstand 1000V (or more) across it. However, if the insulation has deteriorated, it could easily break down with perhaps 100V applied across it and a conventional multimeter won’t find this. Two modern 8µF 500V electrolytics had been installed in the set previously. I also found that a number of other capacitors in one of the shielded boxes needed replacement. An ohmmeter gave the “all-clear” but the high voltage tester said otherwise. These were all replaced with the nearest equivalent values I could find. No HT to earth shorts were found in the set, so it was all clear in this respect. The 2-core mains power lead was 92  Silicon Chip replaced with a 3-core lead to ensure safety. Actually, the mains lead had been replaced at some time in the past and the earth lead had been cut off! That all-important earth connection is now back in place. The big test With the valves removed, power was applied to make sure that the voltages around the chassis were roughly correct and that the power transformer was in good order. Nothing heated up, so this was a good sign. Next, the rectifier valve was installed and the receiver switched on with a 1.5kΩ resistor in place of the field coil. A few quick checks with a multimeter revealed that all was well – the various heater voltages were there and each section of the high-voltage transformer winding gave the same voltage. I then ran the set for a short period but found that some of the voltag­es were dropping off and that one of the metal boxes was getting warm. With the power off, I disconnected some of the wiring bet­ween the two metal boxes and discovered that one box was full of paper block capac- itors, all of which were faulty (the second box was full of filter chokes). As a result, these capacitors were all replaced with polyester or electrolytic capacitors as appro­priate. Finding exact replacements is not easy these days, so the new capacitors all have greater capacitance than the originals (the voltage ratings are the same). The set’s owner wanted the set to look as original as possible, without going to extremes to make everything absolutely authentic under the chassis. Once the faulty capacitors were bypassed (they are still there in the can), the HT voltage remained constant at nearly 500V with no load. At this point, the UX245 audio output valves were installed and a test loudspeaker attached. All went well, with the valves drawing the expected current. I then connected an audio oscilla­ tor to the primary of the audio driver transformer and swept the output frequency across the audio spectrum. The response was quite reasonable for such an old set and I was able to hear signals from around 100Hz up to about 8kHz – not bad for 1929. Front-end overhaul The next step was to overhaul the RF, detector and first audio stages. As before, I traced the circuit out ELECTRONIC VALVE & TUBE COMPANY The Electronic Valve & Tube Company (EVATCO) stocks a large range of valves for vintage radio, amateur radio, industrial and small transmitting use. Major current brands such as SOV-TEK and SVETLANA are always stocked and we can supply some rare NOS (New - Old stock) brands such as Mullard, Telefunken, RCA and Philips. Hard to get high-voltage electrolytic capacitors and valve sockets are also available together with a wide range of books covering valve specifications, design and/or modification of valve audio amplifiers. PO Box 487 Drysdale, Victoria 3222. Tel: (03) 5257 2297; Fax: (03) 5257 1773 Mob: 0417 143 167; email: evatco<at>mira.net New premises at: 76 Bluff Road, St Leonards, Vic 3223 There’s ample room inside the cabinet for the two large chassis sections and the big electrodynamic loudspeaker. and this re­vealed a conventional TRF front end. The volume control consists of a potentiometer which is across part of the antenna coil, between the antenna and earth. It is quite effective. The output from the coil is then fed to the receiver which uses four UX226 triodes as RF stages. As shown in the circuit, the first RF stage is untuned but all the others are tuned. A switch between the second and third stages bypasses the primary of one RF coil to lower the gain in high signal strength areas. This switch is mounted beneath the tuning knob and has no escutcheon which makes me suspect that this was an addition sometime during the life of the set. An 800Ω resistor is included in series with the grid of each RF valve to limit its amplification and maintain stability, as no neutralisation has been included. The signal from the RF stages is then fed to a UX227 (V5) wired as a grid leak detector. The 227 plate wiring goes to the six terminal strip and from there to the switch which does the change over from gram to radio. The tuning capacitors in this set are all single gang and are coupled together via brass bands and pulleys – see photo. The coils consist of two formers in each stage and each former has half the tuned winding wound on it. The primary is wound inside one of the coils. This is a similar style to that used in some Atwater Kent receivers of the same vintage. The radio/gram changeover switch and the six terminal strip were originally wired in such a manner that the pickup head was live to a few volts from the receiver HT supply. However, if the earth parted company, anyone touching the pick-up terminals received a nasty shock. Occasionally, equipment was wired like this in the early days but not for me thank you. I made a minor alteration to the wiring so that no HT (or part thereof) appeared on the pickup. The audio from the detector (or from the pickup) is applied to an audio transformer, which feeds a pair of UX226 valves in push pull. An interesting feature here is that a choke and ca­ pacitor (wired in series) are switched into circuit between the two plates when the unit is in radio mode. This is a series-tuned hum-reducing circuit and it does quite a reasonable job. However, it isn’t economically possible to completely rid a set of hum when directly heated valves are used MARCH 2001  93 The controls are relatively simple and include a volume control (left), a central tuning knob and a power switch (right). The local/DX switch below the tuning knob is probably not an original feature. on alternating current. In this case, I believe that some of the problem relates to poor circuit layout around the detector stage. The 226s are connected by the large multi-conductor cable to a push-pull to push-pull audio transformer on the power supply/audio output chassis. This transformer in turn drives the push-pull audio output stage (2 x UX245) which then drives the loudspeaker. By the way, this is the first audio amplifier of this vin­ tage in which I’ve seen a push-pull stage driving a push-pull stage. The fixed capacitors in the “frontend” chassis were tested and although a couple were quite leaky, they were only RF bypass­es from filaments to earth in the RF stages. As a result, the voltage on them was quite low and so the leakage was not of any real concern. Another RF bypass capacitor on the HT line was replaced as a precaution, as it has 170V across it when the set is operating. The mica capacitors throughout the set were all found to be in good order. Finally, the voltages in the RF section of the receiver were checked with no valves fitted and found to be in the range expected. The valves were then 94  Silicon Chip plugged in, the power turned on and the voltages rechecked. There were no nasty surprises and the set started to play music. How good is it? I connected an aerial and earth to the receiver and was greeted with reasonable performance on quite a few stations. Certainly, the set has plenty of go and it doesn’t disgrace itself when compared to many more modern sets. The tracking is reasonably good and no double-spotting or odd tuning characteristics were observed. The volume control works quite well and the local/distance switch is quite effec­tive. However, the latter appears to be unneces­sary as no sign of overload was evident and there are a couple of reasonably powerful broadcast stations within 20km. As men­tioned earlier, I suspect that it was an add-on. Next, I checked the alignment of the four tuned stages. There are no iron dust cores in the RF coils (well before their time) and there are no trimmer capacitors either, so I wanted to find out if the stages tracked each other reasonably accurately. To test them, I slid a small ferrite rod into each coil in turn and noted whether there was any improvement or drop-off in performance. In some cases, there was a slight “lift” in perfor­mance as I approached the coil, while in the other cases the performance deteriorated. This occurred at both ends of the dial. The alignment, despite the lack of adjustments, was close and it was only possible to lift the performance slightly at the high frequency end by connecting two small trimmers across two of the coils. However, for some reason, the set will only tune from 530kHz to 1350kHz. This may have been planned although I suspect that moisture over the years has added distributed capacity across the coils and tuning capacitors, causing them to tune a lower range of frequencies than they did when the set was new. Normally, the tuning range should be from 550kHz to 1500kHz. The overall sensitivity of the set was such that a 100-300µV signal was necessary at the antenna to get reasonable performance. I received a dozen stations effectively here in Mooroopna, northern Victoria. Directly-heated valves It’s interesting to note that the sets of this era almost exclusively used directly-heated valves. As a result, several techniques were employed to overcome the inevitable hum in the receiver’s output when low-voltage AC was applied to the fila­ments. Low-voltage filaments One “trick” was to use low-voltage high-current filaments which had high thermal inertia. Another was to centre-tap the filament winding on the transformer and connect the bias resistor from this point to earth. However, this was not always practical because of the number of filament windings involved (there are five in this set). There are no centre-tapped filament windings in this set, so two 11Ω resistors are used across some windings and the bias resistor connected from their junction to earth. The exception is the audio driver stage, where the resistor across the filament winding is a variable wirewound pot and the bias resistor is connected to the wiper. This pot is adjusted for minimum hum in the output. Because the low-voltage filaments draw such high currents, it is necessary to have heavy filament supply wires. The four 226 valves in the RF section draw 4.2A at 1.5V which means that the cables must be heavy to minimise the voltage drop. In this case, the filament transformer is on the lower chassis and the 226s are on the upper chassis and are fed via a lengthy cable. As a re­sult, the voltage on the valve filaments is around 1.3V instead of the intended 1.5V. The final word I wasn’t around in 1929 to observe the relative performance of this set and others of its era in the conditions that pre­vailed then. However, I believe that this set would have been at the top of the pile when it came to dragging in stations and giving good quality reproduction on both radio and records. Its biggest disadvantage would have been its enormous cost. As such, not many would have been produced and there would now only be a few left in collections. In short, the AWA C58 is a magnificent example of a top-of-the-line Australian receiver from the late 1920s. It is a worth­while addition to any colSC lection if you have the room. MORE FROM YOUR EFI CAR! EFI TECH SPECIAL Own an EFI car? Want to get the best from it? You’ll find all you need to know in this publication HERE ARE JUST SOME OF THE CONTENTS . . .  Making Your EFI Car Go Harder  Building A Mixture Meter  D-I-Y Head Jobs  Fault Finding EFI Systems  $70 Boost Control For 23% More Grunt  All About Engine Management  Modifying Engine Management Systems  Water/Air Intercooling  How To Use A Multimeter  Wiring An Engine Transplant  And Much More Including Some Awesome Engines! AVAILABLE DIRECT FROM SILICON CHIP PUBLICATIONS PO BOX 139, COLLAROY NSW 2097 - $8.95 Inc GST & P&P To order your copy, call (02) 9979 5644 9-5 Mon-Fri with your credit card details! FROM THE PUBLISHERS OF “SILICON CHIP” MARCH 2001  95 Silicon Chip Back Issues April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; 32-Band Graphic Equaliser, Pt.2. May 1989: Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference. July 1989: Exhaust Gas Monitor; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; The NSW 86 Class Electrics. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; High Or Low Fluid Level Detector; Studio Series 20-Band Stereo Equaliser, Pt.2. October 1989: FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 2-Chip Portable AM Stereo Radio, Pt.2. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio, Pt.3; Floppy Disk Drive Formats & Options. July 1993: Single Chip Message Recorder; Light Beam Relay Extender; AM Radio Trainer, Pt.2; Quiz Game Adjudicator; Windows-Based Logic Analyser, Pt.2; Antenna Tuners – Why They Are Useful. August 1993: Low-Cost Colour Video Fader; 60-LED Brake Light Array; Microprocessor-Based Sidereal Clock; A Look At Satellites & Their Orbits. September 1993: Automatic Nicad Battery Charger/Discharger; Stereo Preamplifier With IR Remote Control, Pt.1; In-Circuit Transistor Tester; +5V to ±15V DC Converter; Remote-Controlled Cockroach. April 1991: Steam Sound Simulator For Model Railroads; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2. May 1991: 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1. July 1991: 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. September 1991: Digital Altimeter For Gliders & Ultralights; Ultrasonic Switch For Mains Appliances; The Basics Of A/D & D/A Conversion; Plotting The Course Of Thunderstorms. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator For Model Railways Mk.II; Magnetic Field Strength Meter; Digital Altimeter For Gliders, Pt.2; Military Applications Of R/C Aircraft. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Phone Patch For Radio Amateurs; Active Antenna Kit; Designing UHF Transmitter Stages. November 1991: Colour TV Pattern Generator, Pt.1; A Junkbox 2-Valve Receiver; Flashing Alarm Light For Cars; Digital Altimeter For Gliders, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2; A Turnstile Antenna For Weather Satellite Reception. February 1990: A 16-Channel Mixing Desk; Build A High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2. December 1991: TV Transmitter For VCRs With UHF Modulators; Infrared Light Beam Relay; Colour TV Pattern Generator, Pt.2; Index To Volume 4. March 1990: Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V 8A Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Experiments For Your Games Card. April 1990: Dual Tracking ±50V Power Supply; Voice-Operated Switch (VOX) With Delayed Audio; 16-Channel Mixing Desk, Pt.3; Active CW Filter; Servicing Your Microwave Oven. March 1992: TV Transmitter For VHF VCRs; Thermostatic Switch For Car Radiator Fans; Coping With Damaged Computer Directories; Valve Substitution In Vintage Radios. June 1990: Multi-Sector Home Burglar Alarm; Build A Low-Noise Universal Stereo Preamplifier; Load Protector For Power Supplies. April 1992: IR Remote Control For Model Railroads; Differential Input Buffer For CROs; Understanding Computer Memory; Aligning Vintage Radio Receivers, Pt.1. July 1990: Digital Sine/Square Generator, Pt.1 (covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Build A Simple Electronic Die; A Low-Cost Dual Power Supply. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Generator, Pt.2. September 1990: A Low-Cost 3-Digit Counter Module; Build A Simple Shortwave Converter For The 2-Metre Band; The Care & Feeding Of Nicad Battery Packs (Getting The Most From Nicad Batteries). October 1990: The Dangers of PCBs; Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; NE602 Converter Circuits. November 1990: Connecting Two TV Sets To One VCR; Build An Egg Timer; Low-Cost Model Train Controller; 1.5V To 9V DC Converter; Introduction To Digital Electronics; A 6-Metre Amateur Transmitter. December 1990: 100W DC-DC Converter For Car Amplifiers; Wiper Pulser For Rear Windows; 4-Digit Combination Lock; 5W Power Amplifier For The 6-Metre Amateur Transmitter; Index To Volume 3. \January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine (Simple Poker Machine); Build A Two-Tone Alarm Module; The Dangers of Servicing Microwave Ovens. March 1991: Transistor Beta Tester Mk.2; A Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose I/O Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateur Radio & TV. ORDER FORM Please send thethe following back issues: Please send following back issues:    October 1993: Courtesy Light Switch-Off Timer For Cars; Wireless Microphone For Musicians; Stereo Preamplifier With IR Remote Control, Pt.2; Electronic Engine Management, Pt.1. November 1993: High Efficiency Inverter For Fluorescent Tubes; Stereo Preamplifier With IR Remote Control, Pt.3; Siren Sound Generator; Engine Management, Pt.2; Experiments For Games Cards. December 1993: Remote Controller For Garage Doors; Build A LED Stroboscope; Build A 25W Audio Amplifier Module; A 1-Chip Melody Generator; Engine Management, Pt.3; Index To Volume 6. January 1994: 3A 40V Variable Power Supply; Solar Panel Switching Regulator; Printer Status Indicator; Mini Drill Speed Controller; Stepper Motor Controller; Active Filter Design; Engine Management, Pt.4. February 1994: Build A 90-Second Message Recorder; 12-240VAC 200W Inverter; 0.5W Audio Amplifier; 3A 40V Adjustable Power Supply; Engine Management, Pt.5; Airbags In Cars – How They Work. March 1994: Intelligent IR Remote Controller; 50W (LM3876) Audio Amplifier Module; Level Crossing Detector For Model Railways; Voice Activated Switch For FM Microphones; Engine Management, Pt.6. April 1994: Sound & Lights For Model Railway Level Crossings; Discrete Dual Supply Voltage Regulator; Universal Stereo Preamplifier; Digital Water Tank Gauge; Engine Management, Pt.7. May 1994: Fast Charger For Nicad Batteries; Induction Balance Metal Locator; Multi-Channel Infrared Remote Control; Dual Electronic Dice; Simple Servo Driver Circuits; Engine Management, Pt.8. June 1994: 200W/350W Mosfet Amplifier Module; A Coolant Level Alarm For Your Car; 80-Metre AM/CW Transmitter For Amateurs; Converting Phono Inputs To Line Inputs; PC-Based Nicad Battery Monitor; Engine Management, Pt.9. July 1994: Build A 4-Bay Bow-Tie UHF TV Antenna; PreChamp 2-Transistor Preamplifier; Steam Train Whistle & Diesel Horn Simulator; 6V SLA Battery Charger; Electronic Engine Management, Pt.10. June 1992: Multi-Station Headset Intercom, Pt.1; Video Switcher For Camcorders & VCRs; IR Remote Control For Model Railroads, Pt.3; 15-Watt 12-240V Inverter; A Look At Hard Disk Drives. August 1994: High-Power Dimmer For Incandescent Lights; Microprocessor-Controlled Morse Keyer; Dual Diversity Tuner For FM Microphones, Pt.1; Nicad Zapper (For Resurrecting Nicad Batteries); Engine Management, Pt.11. August 1992: Automatic SLA Battery Charger; Miniature 1.5V To 9V DC Converter; 1kW Dummy Load Box For Audio Amplifiers; Troubleshooting Vintage Radio Receivers; The MIDI Interface Explained. September 1994: Automatic Discharger For Nicad Battery Packs; MiniVox Voice Operated Relay; Image Intensified Night Viewer; AM Radio For Weather Beacons; Dual Diversity Tuner For FM Microphones, Pt.2; Engine Management, Pt.12. October 1992: 2kW 24VDC - 240VAC Sinewave Inverter; Multi-Sector Home Burglar Alarm, Pt.2; Mini Amplifier For Personal Stereos; A Regulated Lead-Acid Battery Charger. January 1993: 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. February 1993: Three Projects For Model Railroads; Low Fuel Indicator For Cars; Audio Level/VU Meter (LED Readout); An Electronic Cockroach; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.5. March 1993: Solar Charger For 12V Batteries; Alarm-Triggered Security Camera; Reaction Trainer; Audio Mixer for Camcorders; A 24-Hour Sidereal Clock For Astronomers. April 1993: Solar-Powered Electric Fence; Audio Power Meter; Three-Function Home Weather Station; 12VDC To 70VDC Converter; Digital Clock With Battery Back-Up. June 1993: AM Radio Trainer, Pt.1; Remote Control For The Woofer Stopper; Digital Voltmeter For Cars; Windows-Based Logic Analyser. October 1994: How Dolby Surround Sound Works; Dual Rail Variable Power Supply; Build A Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Build A Temperature Controlled Soldering Station; Electronic Engine Management, Pt.13. November 1994: Dry Cell Battery Rejuvenator; Novel Alphanumeric Clock; 80-Metre DSB Amateur Transmitter; Twin-Cell Nicad Discharger (See May 1993); How To Plot Patterns Direct to PC Boards. December 1994: Easy-To-Build Car Burglar Alarm; Three-Spot Low Distortion Sinewave Oscillator; Clifford – A Pesky Electronic Cricket; Remote Control System for Models, Pt.1; Index to Vol.7. January 1995: Sun Tracker For Solar Panels; Battery Saver For Torches; Dolby Pro-Logic Surround Sound Decoder, Pt.2; Dual Channel UHF Remote Control; Stereo Microphone Pre­amp­lifier. February 1995: 50-Watt/Channel Stereo Amplifier Module; Digital Effects Unit For Musicians; 6-Channel Thermometer With LCD Readout; Wide Range Electrostatic Loudspeakers, Pt.1; Oil Change Timer For Cars; Remote Control System For Models, Pt.2. ____________________________________________________________ Enclosed is my cheque/money order for $­______or please debit my: ❏ Bankcard ❏ Visa Card ❏ Master Card Card No. Signature ___________________________ Card expiry date_____ /______ Name ______________________________ Phone No (___) ____________ PLEASE PRINT Street ______________________________________________________ Suburb/town _______________________________ Postcode ___________ 96  Silicon Chip 10% OF F SUBSCR TO IB OR IF Y ERS OU 10 OR M BUY ORE Note: prices include postage & packing Australia ....................... $A7.70 (incl. GST) Overseas (airmail) ............................ $A10 Detach and mail to: Silicon Chip Publications, PO Box 139, Collaroy, NSW, Australia 2097. Or call (02) 9979 5644 & quote your credit card details or fax the details to (02) 9979 6503. Email: silchip<at>siliconchip.com.au March 1995: 50 Watt Per Channel Stereo Amplifier, Pt.1; Subcarrier Decoder For FM Receivers; Wide Range Electrostatic Loudspeakers, Pt.2; IR Illuminator For CCD Cameras; Remote Control System For Models, Pt.3; Simple CW Filter. June 1997: PC-Controlled Thermometer/Thermostat; Colour TV Pattern Generator, Pt.1; Build An Audio/RF Signal Tracer; High-Current Speed Controller For 12V/24V Motors; Manual Control Circuit For A Stepper Motor; Cathode Ray Oscilloscopes, Pt.10. July 1999: Build The Dog Silencer; A 10µH to 19.99mH Inductance Meter; Build An Audio-Video Transmitter; Programmable Ignition Timing Module For Cars, Pt.2; XYZ Table With Stepper Motor Control, Pt.3; The Hexapod Robot. April 1995: FM Radio Trainer, Pt.1; Photographic Timer For Dark­ rooms; Balanced Microphone Preamp. & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. July 1997: Infrared Remote Volume Control; A Flexible Interface Card For PCs; Points Controller For Model Railways; Simple Square/Triangle Waveform Generator; Colour TV Pattern Generator, Pt.2; An In-Line Mixer For Radio Control Receivers. August 1999: Remote Modem Controller; Daytime Running Lights For Cars; Build A PC Monitor Checker; Switching Temperature Controller; XYZ Table With Stepper Motor Control, Pt.4; Electric Lighting, Pt.14; DOS & Windows Utilities For Reversing Protel PC Board Files. May 1995: Build A Guitar Headphone Amplifier; FM Radio Trainer, Pt.2; Transistor/Mosfet Tester For DMMs; A 16-Channel Decoder For Radio Remote Control; Introduction to Satellite TV. August 1997: The Bass Barrel Subwoofer; 500 Watt Audio Power Amplifier Module; A TENs Unit For Pain Relief; Addressable PC Card For Stepper Motor Control; Remote Controlled Gates For Your Home. June 1995: Build A Satellite TV Receiver; Train Detector For Model Railways; 1W Audio Amplifier Trainer; Low-Cost Video Security System; Multi-Channel Radio Control Transmitter For Models, Pt.1. September 1997: Multi-Spark Capacitor Discharge Ignition; 500W Audio Power Amplifier, Pt.2; A Video Security System For Your Home; PC Card For Controlling Two Stepper Motors; HiFi On A Budget. September 1999: Automatic Addressing On TCP/IP Networks; Autonomouse The Robot, Pt.1; Voice Direct Speech Recognition Module; Digital Electrolytic Capacitance Meter; XYZ Table With Stepper Motor Control, Pt.5; Peltier-Powered Can Cooler. July 1995: Electric Fence Controller; How To Run Two Trains On A Single Track (Incl. Lights & Sound); Setting Up A Satellite TV Ground Station; Build A Reliable Door Minder. October 1997: Build A 5-Digit Tachometer; Add Central Locking To Your Car; PC-Controlled 6-Channel Voltmeter; 500W Audio Power Amplifier, Pt.3; Customising The Windows 95 Start Menu. August 1995: Fuel Injector Monitor For Cars; Gain Controlled Microphone Preamp; Audio Lab PC-Controlled Test Instrument, Pt.1; How To Identify IDE Hard Disk Drive Parameters. November 1997: Heavy Duty 10A 240VAC Motor Speed Controller; Easy-To-Use Cable & Wiring Tester; Build A Musical Doorbell; Relocating Your CD-ROM Drive; Replacing Foam Speaker Surrounds; Understanding Electric Lighting Pt.1. September 1995: Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.1; Keypad Combination Lock; The Vader Voice; Jacob’s Ladder Display; Audio Lab PC-Controlled Test Instrument, Pt.2. October 1995: 3-Way Bass Reflex Loudspeaker System; Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.2; Fast Charger For Nicad Batteries; Digital Speedometer & Fuel Gauge For Cars, Pt.1. November 1995: Mixture Display For Fuel Injected Cars; CB Trans­ verter For The 80M Amateur Band, Pt.1; PIR Movement Detector; Dolby Pro Logic Surround Sound Decoder Mk.2, Pt.1; Digital Speedometer & Fuel Gauge For Cars, Pt.2. December 1995: Engine Immobiliser; 5-Band Equaliser; CB Transverter For The 80M Amateur Band, Pt.2; Subwoofer Controller; Dolby Pro Logic Surround Sound Decoder Mk.2, Pt.2; Knock Sensing In Cars; Index To Volume 8. January 1996: Surround Sound Mixer & Decoder, Pt.1; Magnetic Card Reader; Build An Automatic Sprinkler Controller; IR Remote Control For The Railpower Mk.2; Recharging Nicad Batteries For Long Life. April 1996: Cheap Battery Refills For Mobile Telephones; 125W Audio Power Amplifier Module; Knock Indicator For Leaded Petrol Engines; Multi-Channel Radio Control Transmitter; Pt.3; Cathode Ray Oscilloscopes, Pt.2. May 1996: Upgrading The CPU In Your PC; High Voltage Insulation Tester; Knightrider Bi-Directional LED Chaser; Simple Duplex Intercom Using Fibre Optic Cable; Cathode Ray Oscilloscopes, Pt.3. June 1996: BassBox CAD Loudspeaker Software Reviewed; Stereo Simulator (uses delay chip); Rope Light Chaser; Low Ohms Tester For Your DMM; Automatic 10A Battery Charger. July 1996: Installing a Dual Boot Windows System On Your PC; Build A VGA Digital Oscilloscope, Pt.1; Remote Control Extender For VCRs; 2A SLA Battery Charger; 3-Band Parametric Equaliser; Single Channel 8-bit Data Logger. August 1996: Introduction to IGBTs; Electronic Starter For Fluores­ cent Lamps; VGA Oscilloscope, Pt.2; 350W Amplifier Module; Masthead Amplifier For TV & FM; Cathode Ray Oscilloscopes, Pt.4. September 1996: VGA Oscilloscope, Pt.3; IR Stereo Headphone Link, Pt.1; High Quality PA Loudspeaker; 3-Band HF Amateur Radio Receiver; Cathode Ray Oscilloscopes, Pt.5. October 1996: Send Video Signals Over Twisted Pair Cable; Power Control With A Light Dimmer; 600W DC-DC Converter For Car Hifi Systems, Pt.1; IR Stereo Headphone Link, Pt.2; Build A Multi-Media Sound System, Pt.1; Multi-Channel Radio Control Transmitter, Pt.8. November 1996: Adding A Parallel Port To Your Computer; 8-Channel Stereo Mixer, Pt.1; Low-Cost Fluorescent Light Inverter; How To Repair Domestic Light Dimmers; Build A Multi-Media Sound System, Pt.2; 600W DC-DC Converter For Car Hifi Systems, Pt.2. December 1996: Build An Active Filter & Clean Up Your CW Reception; A Fast Clock For Railway Modellers; Laser Pistol & Electronic Target; Build A Sound Level Meter; 8-Channel Stereo Mixer, Pt.2; Index To Volume 9. January 1997: How To Network Your PC; Control Panel For Multiple Smoke Alarms, Pt.1; Build A Pink Noise Source (For Sound Level Meter Calibration); Computer Controlled Dual Power Supply, Pt.1; Digi-Temp Monitors Eight Temperatures. February 1997: Cathode Ray Oscilloscopes, Pt.6; PC-Con­trolled Moving Message Display; Computer Controlled Dual Power Supply, Pt.2; The Alert-A-Phone Loud Sounding Telephone Alarm; Build A Control Panel For Multiple Smoke Alarms, Pt.2. March 1997: Driving A Computer By Remote Control; Plastic Power PA Amplifier (175W); Signalling & Lighting For Model Railways; Build A Jumbo LED Clock; Cathode Ray Oscilloscopes, Pt.7. April 1997: Simple Timer With No ICs; Digital Voltmeter For Cars; Loudspeaker Protector For Stereo Amplifiers; Model Train Controller; A Look At Signal Tracing; Pt.1; Cathode Ray Oscilloscopes, Pt.8. May 1997: Neon Tube Modulator For Light Systems; Traffic Lights For A Model Intersection; The Spacewriter – It Writes Messages In Thin Air; A Look At Signal Tracing; Pt.2; Cathode Ray Oscilloscopes, Pt.9. October 1999: Sharing A Modem For Internet & Email Access (WinGate); Build The Railpower Model Train Controller, Pt.1; Semiconductor Curve Tracer; Autonomouse The Robot, Pt.2; XYZ Table With Stepper Motor Control, Pt.6; Introducing Home Theatre. November 1999: USB – Hassle-Free Connections TO Your PC; Electric Lighting, Pt.15; Setting Up An Email Server; Speed Alarm For Cars, Pt.1; Multi-Colour LED Christmas Tree; Build An Intercom Station Expander; Foldback Loudspeaker System For Musicians; Railpower Model Train Controller, Pt.2. December 1997: Build A Speed Alarm For Your Car; Two-Axis Robot With Gripper; Loudness Control For Car Hifi Systems; Stepper Motor Driver With Onboard Buffer; Power Supply For Stepper Motor Cards; Understanding Electric Lighting Pt.2; Index To Volume 10. December 1999: Internet Connection Sharing Using Hardware; Electric Lighting, Pt.16; Build A Solar Panel Regulator; The PC Powerhouse (gives fixed +12V, +9V, +6V & +5V rails); The Fortune Finder Metal Locator; Speed Alarm For Cars, Pt.2; Railpower Model Train Controller, Pt.3; Index To Volume 12. January 1998: Build Your Own 4-Channel Lightshow, Pt.1 (runs off 12VDC or 12VAC); Command Control System For Model Railways, Pt.1; Pan Controller For CCD Cameras; Build A One Or Two-Lamp Flasher; Understanding Electric Lighting, Pt.3. January 2000: Spring Reverberation Module; An Audio-Video Test Generator; Build The Picman Programmable Robot; A Parallel Port Interface Card; Off-Hook Indicator For Telephone Lines; B&W Nautilus 801 Monitor Loudspeakers (Review). February 1998: Multi-Purpose Fast Battery Charger, Pt.1; Telephone Exchange Simulator For Testing; Command Control System For Model Railways, Pt.2; Build Your Own 4-Channel Lightshow, Pt.2; Understanding Electric Lighting, Pt.4. February 2000: Multi-Sector Sprinkler Controller; A Digital Voltmeter For Your Car; An Ultrasonic Parking Radar; Build A Safety Switch Checker; Build A Sine/Square Wave Oscillator; Marantz SR-18 Home Theatre Receiver (Review); The “Hot Chip” Starter Kit (Review). April 1998: Automatic Garage Door Opener, Pt.1; 40V 8A Adjustable Power Supply, Pt.1; PC-Controlled 0-30kHz Sinewave Generator; Build A Laser Light Show; Understanding Electric Lighting; Pt.6. March 2000: Doing A Lazarus On An Old Computer; Ultra Low Distortion 100W Amplifier Module, Pt.1; Electronic Wind Vane With 16-LED Display; Glowplug Driver For Powered Models; The OzTrip Car Computer, Pt.1; Multisim Circuit Design & Simulation Package (Review). May 1998: Troubleshooting Your PC, Pt.1; Build A 3-LED Logic Probe; Automatic Garage Door Opener, Pt.2; Command Control For Model Railways, Pt.4; 40V 8A Adjustable Power Supply, Pt.2. June 1998: Troubleshooting Your PC, Pt.2; Understanding Electric Lighting, Pt.7; Universal High Energy Ignition System; The Roadies’ Friend Cable Tester; Universal Stepper Motor Controller; Command Control For Model Railways, Pt.5. July 1998: Troubleshooting Your PC, Pt.3 (Installing A Modem And Solving Problems); Build A Heat Controller; 15-Watt Class-A Audio Amplifier Module; Simple Charger For 6V & 12V SLA Batteries; Automatic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. August 1998: Troubleshooting Your PC, Pt.4 (Adding Extra Memory); Build The Opus One Loudspeaker System; Simple I/O Card With Automatic Data Logging; Beat Triggered Strobe; 15-Watt Class-A Stereo Amplifier. September 1998: Troubleshooting Your PC, Pt.5 (Software Problems & DOS Games); A Blocked Air-Filter Alarm; A Waa-Waa Pedal For Your Guitar; Build A Plasma Display Or Jacob’s Ladder; Gear Change Indicator For Cars; Capacity Indicator For Rechargeable Batteries. October 1998: Lab Quality AC Millivoltmeter, Pt.1; PC-Controlled StressO-Meter; Versatile Electronic Guitar Limiter; 12V Trickle Charger For Float Conditions; Adding An External Battery Pack To Your Flashgun. November 1998: The Christmas Star (Microprocessor-Controlled Christmas Decoration); A Turbo Timer For Cars; Build A Poker Machine, Pt.1; FM Transmitter For Musicians; Lab Quality AC Millivoltmeter, Pt.2; Setting Up A LAN Using TCP/IP; Understanding Electric Lighting, Pt.9; Improving AM Radio Reception, Pt.1. December 1998: Protect Your Car With The Engine Immobiliser Mk.2; Thermocouple Adaptor For DMMs; A Regulated 12V DC Plugpack; Build Your Own Poker Machine, Pt.2; Improving AM Radio Reception, Pt.2; Mixer Module For F3B Glider Operations. January 1999: High-Voltage Megohm Tester; Getting Started With BASIC Stamp; LED Bargraph Ammeter For Cars; Keypad Engine Immobiliser; Improving AM Radio Reception, Pt.3; Electric Lighting, Pt.10 February 1999: Installing A Computer Network; Making Front Panels For Your Projects; Low Distortion Audio Signal Generator, Pt.1; Command Control Decoder For Model Railways; Build A Digital Capacitance Meter; Build A Remote Control Tester; Electric Lighting, Pt.11. March 1999: Getting Started With Linux; Pt.1; Build A Digital Anemometer; 3-Channel Current Monitor With Data Logging; Simple DIY PIC Programmer; Easy-To-Build Audio Compressor; Low Distortion Audio Signal Generator, Pt.2; Electric Lighting, Pt.12. April 1999: Getting Started With Linux; Pt.2; High-Power Electric Fence Controller; Bass Cube Subwoofer; Programmable Thermostat/ Thermometer; Build An Infrared Sentry; Rev Limiter For Cars; Electric Lighting, Pt.13; Autopilots For Radio-Controlled Model Aircraft. May 1999: The Line Dancer Robot; An X-Y Table With Stepper Motor Control, Pt.1; Three Electric Fence Testers; Heart Of LEDs; Build A Carbon Monoxide Alarm; Getting Started With Linux; Pt.3. June 1999: FM Radio Tuner Card For PCs; X-Y Table With Stepper Motor Control, Pt.2; Programmable Ignition Timing Module For Cars, Pt.1; Hard Disk Drive Upgrades Without Reinstalling Software; What Is A Groundplane Antenna?; Getting Started With Linux; Pt.4. April 2000: A Digital Tachometer For Your Car; RoomGuard – A LowCost Intruder Alarm; Build A Hot wire Cutter; The OzTrip Car Computer, Pt.2; Build A Temperature Logger; Atmel’s ICE 200 In-Circuit Emulator; How To Run A 3-Phase Induction Motor From 240VAC. May 2000: Ultra-LD Stereo Amplifier, Pt.2; Build A LED Dice (With PIC Microcontroller); Low-Cost AT Keyboard Translator (Converts IBM Scan-Codes To ASCII); 50A Motor Speed Controller For Models; What’s Inside A Furby. June 2000: Automatic Rain Gauge With Digital Readout; Parallel Port VHF FM Receiver; Li’l Powerhouse Switchmode Power Supply (1.23V to 40V) Pt.1; CD Compressor For Cars Or The Home. July 2000: A Moving Message Display; Compact Fluorescent Lamp Driver; El-Cheapo Musicians’ Lead Tester; Li’l Powerhouse Switchmode Power Supply (1.23V to 40V) Pt.2; Say Bye-Bye To Your 12V Car Battery. August 2000: Build A Theremin For Really Eeerie Sounds; Come In Spinner (writes messages in “thin-air”); Loudspeaker Protector & Fan Controller For The Ultra-LD Stereo Amplifier; Proximity Switch For 240VAC Lamps; Structured Cabling For Computer Networks. September 2000: Build A Swimming Pool Alarm; An 8-Channel PC Relay Board; Fuel Mixture Display For Cars, Pt.1; Protoboards – The Easy Way Into Electronics, Pt.1; Cybug The Solar Fly; Network Troubleshooting With Fluke’s NetTool. October 2000: Guitar Jammer For Practice & Jam Sessions; Booze Buster Breath Tester; A Wand-Mounted Inspection Camera); Installing A Free-Air Subwoofer In Your Car; Fuel Mixture Display For Cars, Pt.2; Protoboards – The Easy Way Into Electronics, Pt.2. November 2000: Santa & Rudolf Chrissie Display; 2-Channel Guitar Preamplifier, Pt.1; Message Bank & Missed Call Alert; Electronic Thermostat; Protoboards – The Easy Way Into Electronics, Pt.3. December 2000: Home Networking For Shared Internet Access; Build A Bright-White LED Torch; 2-Channel Guitar Preamplifier, Pt.2 (Digital Reverb); Driving An LCD From The Parallel Port; Build A morse Clock; Protoboards – The Easy Way Into Electronics, Pt.4; Index To Vol.13. January 2001: LP Resurrection – Transferring LPs & Tapes To CD; The LP Doctor – Clean Up Clicks & Pops, Pt.1; Arbitrary Waveform Generator; 2-Channel Guitar Preamplifier, Pt.3; PIC Programmer & TestBed; Wireless Networking. February 2001: How To Observe Meteors Using Junked Gear; An Easy Way To Make PC Boards; L’il Pulser Train Controller; Midi-Mate – A MIDI Interface For PCs; Build The Bass Blazer; 2-Metre Elevated Groundplane Antenna; The LP Doctor – Clean Up Clicks & Pops, Pt.2. PLEASE NOTE: November 1987 to March 1989, June 1989, August 1989, December 1989, May 1990, February 1991, June 1991, August 1991, February 1992, July 1992, September 1992, November 1992, December 1992, May 1993, February 1996 and March 1998 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 tear sheets) at $7.70 per article (includes p&p). When supplying photostat articles or back copies, we automatically supply any relevant notes & errata at no extra charge. A complete index to all articles published to date is available on floppy disk for $11 including p&p, or can be downloaded free from our web site: www.siliconchip.com.au MARCH 2001  97 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Wire gauge for white LED torch I’m currently constructing the white LED torch as described in the December 2000 issue of SILICON CHIP. Unfortunately, I am in Perth and none of Dick Smith Electronics, Jaycar or Altronics carry the 0.16mm enamelled copper wire specified for the con­ struction of L1, the 220µH inductor. I was curious as to whether either 0.125 or 0.2mm wire would be suitable and if so, whether any adjustment would be necessary to the number of turns. (J. L., via email). • The wire gauge is not critical. Use 0.2mm if that’s all you can get. How to improve Commodore ventilation I drive a Holden VL Commodore and the ventilation could be a lot better. The heating/cooling/air conditioning fan in the cabin has a four stage switch. (I believe all the VB to VL Com­ modores have pretty much LED displays for bright sunlight Some time ago I purchased and built a couple of the Digital Speedo kits, as featured in the November & December 1999 issues. They are excellent. However, the car in which they are used has a serious problem with reflective light and in bright sunshine the numerals are virtually illegible. I ignored this until I purchased a digital voltmeter kit, which has numerals which are much brighter and very easy to read. I have no need for dimming capability. So my question is, how can I make the digital speedo display as bright as the digital vol­tmeter display? I have disconnected LDR1, VR1 is up full, and changing the seven 150Ω resistors to a lower value has 98  Silicon Chip the same fan and the same switching mechanism). Can you design a circuit that could be connected to the fan to make it run faster? I want it 1.5 times faster on setting 1 and so on. (D. H., via email). • It is possible but it’s not really practical and the fan would be a lot noisier in any case. We’re pretty sure the fan motor will be a permanent magnet type and therefore the speed control is basically just a tapped resistor in series with the motor (it was this speed control which was subject to a recall of the VK Commodore due to a fire hazard!). So since it is a permanent magnet motor, the only way to make the fan run faster is to increase the input voltage and this can only be done by using a relatively high power step-up invert­er. Using a PC for video editing As a keen video editor, I need to control my VCR with my PC using not helped. I think that changing XTAL1 may fix the brightness problem but may change the readings. Can you help? (P. W., via email). • While it may seem that the displays used in the speed alarm are of a lower emission output compared to the voltmeter, in fact both projects should have the same light output if the recommend­ed displays are used. Perhaps you purchased the parts from a different supplier? Where the display is used in bright ambient light condi­tions we would recommend using the sunlight readable HDSPH151 which produce 16mcd of light at 20mA compared to the 1.3mcd from the HDSP-5301 displays. HDSPH151s are available from Farnell Electronics (Cat 264-313). Phone 1300 361 005. the RS-232 port to drive V-LANC or the 5-pin edit control port on VCRs. I hope you have some ideas on how to build such a project. (V. P., via email). • We have not published any article which is relevant to your application but if other readers indicate an interest we shall consider doing a project to suit. Opto-electronic pickup wanted Could you please advise on what brand of opto-electronic pickup was used in the opto-electronic version of the High Energy Ignition article on page 58 of the October 2000 edition of SILI­CON CHIP? And where can I purchase it? (B. G., via email). • We do not know the particular brand of opto sensor. It was requested by a reader who had a sensor with a common ground connec­tion. The circuit can be used with the Crane Cams optoelectronic points replacement unit. These should be available from high performance automotive parts suppliers. Another circuit for this optoelectronic pickup was published in the Circuit Notebook pages of the August 1988 issue. As an alternative to using a commercial unit, you could use a photo-interrupter from Jaycar (Cat ZD-1901) and make up your own interrupter disk to break the infrared beam. Protection components for mixture display I have a mate who runs your bargraph mixture display (SILI­CON CHIP, November 1995) and he keeps blowing the chips. He tells me there is a fix for it you released. So I offered to install it for him but I need to know if you can help me with a description of the fix? (G. M., via email). • You need to add three components: a 39kΩ resistor in series with pin 5, a 10Ω 0.25W resistor in series with the 12V supply and a 15V 1W zener across the 12V supply after the 10Ω resistor. The 15V zener clips off any spikes on the 12V supply. The details were shown in EFI Tech Special which is available from us for $8.95 including postage. Substitute for OP27 in 8-channel mixer I was thinking about building the 8-channel mixer project from your November & December 1996 edition. Can you please tell me where I can get the OP27 op amp or can a substitute be used? If so, which one? Also I don’t intend using microphones, so can the SSM2017 be omitted and the line signal connected directly to VR1 on IC2a (LM833)? (E. Z., via email). • Dick Smith Electronics have the LM627CN which is a direct pin-for-pin equivalent of the OP27. And yes, you can link the line signal to VR1. Gain controlled microphone preamp I have built the gain-controlled preamp described in August 1995 for use in our church. On setting up, using two different microphones, the open R1 is too sensitive with significant hiss and a tendency to run into feedback but the next set of values in Table 1 are not sensitive enough. There is a non-linear relationship between R1 and the parallel C. I am not sure how to select the resistor/ capacitor pairs. Would the pair 6.8kΩ and .0047µF be satisfactory to try as an intermediate set of values between open and the first set of values in Table 1? (G. C., via email). • The value of capacitance is not overly critical. You could use a trimpot for R1 to vary the gain instead of a fixed value. A value of 20kΩ would allow variation in gain over the range re­quired. The use of a .0047µF capacitor would be a good compromise value. For a fixed value of resistance, try 10kΩ and .068µF capacitor. Reflector for beattriggered strobe I was wondering where you got the reflector used in the prototype of the beat-triggered strobe described in the August 1998 issue. I have built the PC board but after quite a bit of shopping around, cannot find a suitable reflector Don’t drive speakers too hard My two main speakers in my hifi system blew a midrange driver whilst testing (at high volume). They are an Epicure model and were supposed to have been rated at 100W. I was sweeping the amplifier with a signal generator at 50W RMS output, about 2/3 the amplifier’s capability. (I thought we had a resonant frequen­cy problem with the setup and was trying to find it). I ran the system at 1kHz (clean and undistorted) for about 40 seconds or so and then it fizzled. Now why did the midrange driver blow? If the speaker is rated at 100W, shouldn’t it be able to take 100W across the frequency range it’s rated for? Having said that, my problem now is replacing the Epicure mid­ range driver. And what’s to stop it from happening again? (M. S., via email). around the size specified, except as part of a very expensive CFL down­ light fitting. Most start at about 300mm (way too big) or below 120mm. I would appreciate any help you could give to point me in the right direction. (J. V., via email). • Those spun aluminium reflectors used to be available as a part from kitset suppliers but now are only available in the kit from Altronics. Have you thought about using a large semi-sealed beam headlight from a wreckers? Might be worth a try and would have the advantage that the front glass is integral. Dead display in digital tacho I have built the digital tacho featured in the April 2000 issue of SILICON CHIP. The problem is that when power is applied only “LO” appears in full height on the display (in the two centre LED segments). I have replaced the PIC with a new one purchased from Jaycar but to no avail. Nothing happens when you press any button. (L. R., via email). • Your problem could be that the switches S1-S3 are oriented incor- • Most speaker ratings refer to normal program material so a speaker rated for 100W would comfortably handle the full output of a 100W amplifier (not driven beyond clipping) on normal program (ie, music) material. The problem is most program material, even rock which has a pretty narrow dynamic range, still would have an average power level of only a few watts, with the amplifier being driven to the onset of clipping. By feeding in 50W you were really going over the top and it is a wonder you weren’t deafened. Even a couple of watts on sinewave over the mid­range is really deafening on most speakers. The moral is this: if you want to test on sinewave, check that your speakers are rated for continuous power. If not, assume they won’t handle it and keep the volume down to the merely loud, otherwise you will easily blow tweeters and midranges. rectly. Try rotating them through 90 degrees. Alternatively, you could be lacking a connection between the two PC boards. Check the contacts between the 7-way sockets and pin headers. Adding memory to the Wavemaker I enjoyed the article on the Wave­ maker in the January 2001 issue – a very practical solution, well implemented. For our application, it would be an advantage to have the capability of storing a single computer-generated complex wave on the PC board so it could be played back continuously. Thereby, the device is not dependent on the presence of an external computer. Can you advise, in general design terms, how you would approach this modification? (P. N., via email). • It would require a complete redesign of the Wavemaker to allow onboard storage and replay of waveforms. As well as stor­ing the waveform file in memory, you also have to save the infor­mation regarding its length and/ or replay speed. It gets fairly complex. A design for a waveform generator along these lines was described about MARCH 2001  99 High efficiency fluoro inverter wanted I have constructed three 20W fluoro light inverters, as described in the February 1991 edition of SILICON CHIP. All perform brilliantly and have cut power consumption by nearly 50% on our solar power system. I have also built the 40W inverter, described in the same article but this has not performed to expectations. While power­ing a 40W tube, the inverter would not draw more than 2.8A when fully warmed up and the secondary voltage measured up to be around 600VAC. When powering a 36W tube only 2.6A could be drawn. The transformer consisted of 500 turns of 0.25mm enamelled copper wire, wound on an ETD29 bobbin, for the secondary and 12 turns of 0.5mm ECW, centre tapped at 6 turns, for the primary plus the base windings. The cores used were made from F44 material rather than N27 stuff and were gapped at 0.6mm to achieve the results above. I tried larger air gaps but the inverter would only fire the tube three years ago, in another Australian electron­ ics magazine. That design might be of interest if you do need a generator that can store the waveform on board. High power light dimming Just recently the need has arisen for a high power (1200W) incandescent lamp dimmer and delving through and settle drawing nearly 4A, with the tube glowing dimly. So I wound another transformer, this time with the second­ary consisting of 5 full layers of 0.25mm enamelled copper wire. The instructions aren’t particularly clear for winding the 40W transformer. Winding 5 layers of 0.25mm will make 400 turns all up. I tried this transformer and ran a 36W tube at 700VAC, with the inverter drawing 2.2A. The transformer cores were gapped at 0.44mm, just like the instructions said. The ballast capacitors are rated at 500VAC but still work. Could you please advise me on what to do to make this cir­ cuit work properly? (N. R., via email). • It is impossible to produce a high efficiency inverter for a 40W fluoro using bipolar power transistors such as TIP3055s. Their gain is low and so is their Ft which means that they cannot switch efficiently at high frequencies. The only way to get high efficiency is to use Mosfets and run at frequencies of 100kHz or more. We produced such a design in the November 1993 issue. my library of SILI­CON CHIP magazines I found the article on a Heat Controller in the July 1998 issue and a High Power Dimmer in the August 1994 issue. Now I realise the Heat Controller is clearly not designed for the job of lamp dimming but I am very attracted to the sim­pler design (there is no transformer for a start). Would it be possible to adapt your circuit to lamp dimming duty by increasing the operating frequency LE of the oscillator or are there other complications that would make this too difficult? (R. M., via email). • The Heat Controller cannot be used to dim lights although your thinking is on the right track. The problem is that the mains frequency is fixed at 50Hz and the heat controller varies the power by applying bursts of 50Hz sinewave to the appliance. The minimum burst is one 20ms cycle. So no matter what you do with the burst rate, a heat con­troller like this, relying on zero voltage switching, will always cause really severe flicker if used to control power to lights. However, if the mains frequency is increased to 400Hz, as it is on aircraft, then this system of light dimming does become prac­tical. Notes & Errata LP Doctor, January 2001: The LM833 op amps that perform the treble filter and output buffer functions for the right channel are referred to in brackets as IC7a & IC7b. These should read IC9a and IC9b, respectively. The left channel IC numbers (IC5a & IC5b) are correct. PIC TestBed, January 2000: The overlay diagram on page 79 shows two resistors with the value 4.kΩ; these should read 4.7kΩ. The circuit diagram on page 78 is correct but shows a 4.7kΩ resistor connected to pin 7 of CON3/4: it should connect to pin 6. The overlay diagram is correct. VHF FM Receiver, June 2000: The circuit diagram on page 28 shows the incorrect pinouts on both the 2N7000 and LM336Z isometric drawings. Reading from the left, the 2N7000 should read “D G S” rather than “G D S” and the LM336Z has the “Adj” and SC “-” pins reversed. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. 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. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. 100  Silicon Chip ECTRONICSHOWCASELECT MicroZed Computers GENUINE STAMP PRODUCTS FROM Scott Edwards Electronics microEngineering Labs & others Easy to learn, easy to use, sophisticated CPU based controllers & peripherals. PO Box 634, ARMIDALE 2350 (296 Cook’s Rd) Ph (02) 6772 2777 – may time out to Mobile 0409 036 775 Fax (02) 6772 8987 http://www.microzed.com.au Most Credit Cards OK Do you want YOUR product or service showcased to Australasia's most important electronics marketplace? CALL ME: RICK WINKLER on (02) 9979 5644 and let me explain how cost effective the SILICON CHIP EMC Technologies' internationally recognised Electromagnetic Compatibility (EMC) test facilities are fully accredited for emissions, immunity and safety standards. ELECTRONICS SHOWCASE can be for YOU! Melbourne: (03) 9335 3333 Sydney: (02) 9899 4599 NEW! HC-5 hi-res Vi deo Distribution Amplifier DVS5 Video & Audio Distribution Amplifier Five identical Video and Stereo outputs plus h/phone & monitor out. S-Video & Composite versions available. Professional quality. EMC Technologies For broadcast, audiovisual and film industries. Wide bandwidth, high output and unconditional stability with hum-cancelling circuitry, front-panel video gain and cable eq adjustments. 240V AC, 120V AC or 24V DC VGS2 Graphics Splitter High resolution 1in/2out VGA splitter. Comes with 1.5m HQ cable and 12V supply. Custom-length HQ VGA cables also available. Check our NEW website for latest prices and MONTHLY SPECIALS www.questronix.com.au Email: questav<at>questronix.com.au Video Processors, Colour Correctors, Stabilisers, TBC’s, Converters, etc. QUESTRONIX All mail: PO Box 548, Wahroonga NSW 2076 MARCH 2001  101 Ph (02) 9477 3596 Fax (02) 9477 3681 Visitors by appointment only MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FRWEEBE YES! Place your classified advertisement in SIL- ICON CHIP Market Centre and your advert will also appear FREE in the Classifieds-on-the-Web page of the SILICON CHIP website, www.siliconchip.com.au And if you include an email address or your website URL in you classified advert, the links will be LIVE in your classified-on-the-web! S! D E I F I S C LAS EXCLUSIVE TO SILICON CHIP! CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads: $11.00 (incl. GST) for up to 12 words plus 55 cents for each additional word. Display ads: $27.50 (incl. GST) 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, fill out the form & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy, NSW 2097. Or fax the details to (02) 9979 6503. Taxation Invoice ABN 49 003 205 490 _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $­__________ or please debit my ❏ Bankcard   ❏ Visa Card   ❏ Master Card Card No. Signature­­­­­­­­­­­­ ________________________ Card expiry date______/______ Name _____________________________________________________ Street _____________________________________________________ Suburb/town _________________________ Postcode______________ 102  Silicon Chip FOR SALE QUAD 1024 H-Pixels from $175 * COLOUR QUAD only ! $389 * DOME VIDEO CAMERAS from $53 ! COLOUR from $77 ! BULLET from $97 TWO YEAR WARRANTY * VCR Controller use a standard home VCR for Surveillance Event Recording Wireless IR Control only $39 * DIY PLUG-IN 20 metre AV Cables from $20 * DOME 480 Line 0.05 Lux SONY CCD & ChipSet from $81 * COLOUR DSP DOME: 400 Line from $139 * 600 + Line from $164 * COLOUR DSP PIN in PIR CASE from $152 * MINI CAMS from $67 * DSP COLOUR from $133 * PC REMOTE VIEW, PAGING, WEBCAM, DVR System High 768 x 576 Resolution from $219 * MULTI­PLEXER 4 Ch from $633 * 4 Ch / 8 Ch Switchers only $79 / $99 ! COLOUR Bullet Cameras from $122 * Digital PC 4 Ch Video Recorder System from $159 * BLEMISH FREE & LOW BLEMISH CCDs * UP TO 5 YEARS WARRANTY * OVERNIGHT DELIVERY * www. allthings.com.au TELEPHONE EXCHANGE SIMULATOR: test equipment without the cost of telephone lines. Melb 9806 0110. http://www.alphalink.com.au/~zenere COVERT VIDEO SURVEILLANCE Tiny Sub-Matchbox from ~ 6 grams Wireless Video & Audio TRANSMITTERS from $77 * Pinhole Cameras from $67. 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Check ‘em out at www.ozitronics.com SEE-in-the-DARK Camera with in-built IR LEDs in Water Resistant Case for disturbance-free Baby - Bird - Animal observation from $147 * DIY Plug-In 20 metre Cable & Plug Pack from $33 * www.allthings.com.au C COMPILERS: everything you need to develop C and ASM software for 68­HC08, 6809, 68HC11, 68HC12, 68­ HC16, 8051/52, 8080/85, 8086, 8096 or AVR: $170.50 each. Macro Cross Assemblers and Disassemblers for above CPUs + 6800/01/03/05, 6502 and 68­HC12 for $88. Debug monitors: $88 for 6 CPUs. All compilers, XASMs and monitors: $5280. 8051/52 Simulator (fast, now incl. 80C320): $88. Try the C-FLEA Virtual Machine for small CPUs, build a “C-Stamp”. Demo desk: FREE. All prices + $5.50 p&p. Atmel Flash CPU Programmer: Handles the 89Cx051, 89C5x and 89Sxx series, and some AVRs in both DIP and PLCC44. Also does most 8-pin EEPROMs. Includes socket for serial ISP cable. $220 $11 p&p. SOIC adaptors: 20-pin $99, 14-pin $93.50, 8-pin $88. Credit cards accepted. GRAN­ TRONICS PTY LTD, PO Box 275, Wentworthville 2145. Ph (02) 9896 7150 or Internet: http://www.grantronics.com.au HOME CCTV Mono / Colour PAKS only ! $119 / $151 Full DIY Plug-In to TV / VCR 20 metre Cable, Plug Pack & Camera www.allthings.com.au RCS HAS MOVED to 41 Arlewis St, Chester Hill 2162 and is now open, with full production. Tel (02) 9738 0330; Fax 9738 0334. rcsradio<at>cia.com.au; www.cia.com.au/rcsradio PCBs MADE, ONE OR MANY. Low prices, hobbyists welcome. Sesame Elec­tronics Pty Ltd. sesame<at>internetezy.com.au; http:// members.tripod.com/~sesame_elec QUAD 4 pixs 1 screen from $247 * Real Time * High better than SUPER-VHS 1024 Pixel Resolution * Time * Date * ROLA AUSTRALIA PH/FAX (08) 8270 3175 WEB SITE WWW.BETTANET.NET.AU/GTD CHECK OUR WEBSITE FOR DETAILS ON KITS AND COMPONENTS • • • • Silvertone’s RC Receiver Still the best little performer available! TRANSMITTER KITS AND MODULES AUDIO MODULES COMPUTER INTERFACE KITS RADIO STATION AUDIO SOFTWARE NEW: Our MP3-CD player in short form for $169 inc GST. Includes the following: processor board, front panel display and tactile keypad; just add a case, cables, 12V power supply and a CD-ROM drive. Play CDs and up to 2600 MP3’s from a CDR. Great for car or home. Satellite TV Reception International satellite TV reception in your home is now affordable. Send for your free info pack containing equipment catalog, satellite lists, etc or call for appointment to view. We can display all satellites from 76.5° to 180°. Still only $129.50 AM or $149.50 FM. May be used with most ppm transmitters. This and many other radio control products available from: Silvertone Electronics, PO Box 580, Riverwood 2210. Phone/Fax (02) 9533 3517. www.silvertone.com.au AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au Positions At Jaycar We are often looking for enthusiastic staff for positions in our retail stores and head office at Rhodes in Sydney. A genuine interest in electronics is a necessity. Phone 02 9743 5222 for current vacancies. Camera Title * Alarm Input / Output * Remote Camera Selection * FREEZE * www.allthings.com.au Video Amplifiers, Stabilisers, TBCs, Converters, Mixers, etc. QUESTRONIX (02) 9477 3596. Go to www.questronix.com.au for Video Equipment, Information, Techo Links & Monthly Specials. USB KITS: 1/O Card, Audio Generator, Voltmeter; also Temperature/Voltage measurement via phone line. http://www.ar.com.au/~softmark USB DEVELOPMENT KIT CY3650, Temperature/Voltage measurement via phone line, PC-controlled VHF Receiver http://www.ar.com.au/~softmark DIY CCTV PAKS 4 Cameras & Switcher .................$354 as above COLOUR .....................$466 4 Cams, Switcher/Monitor ...........$495 as above 14" Monitor ................$528 Need prototype PC boards? We have the solutions – we print electronics! Four-day turnaround, less if urgent; Artwork from your own positive or file; Through hole plating; Prompt postal service; 29 years technical experience; Inexpensive; Superb quality. Printed Electronics, 12A Aristoc Rd, Glen Waverley, Vic 3150. Phone: (03) 9545 3722; Fax: (03) 9545 3561 Call Mike Lynch and check us out! We are the best for low cost, small runs. 4 Cams & QUAD .........................$478 4 COLOUR & QUAD ....................$752 Time-Lapse 24 hr VCR only $699 with CCTV Systems ! MORE at: www.allthings.com.au Fully Plug-In DIY Paks with Cables & Power Supplies ALSO PC Digital Motion / Sound detection & activated Video / Audio Recording systems 08 9349 9413 KIT ASSEMBLY NEVILLE WALKER KIT ASSEMBLY & REPAIR: · Australia wide service · Small production runs · Specialist “one-off” applications Phone Neville Walker (07) 3857 2752 Email flashdog<at>optusnet.com.au continued next page MARCH 2001  103 DON’T MISS THE ’BUS Advertising Index Altronics................................. 78-80 Av-Comm Pty Ltd.......................103 Computronics..............................95 Dick Smith Electronics........... 22-25 Do you feel left behind by the latest advances in com­puter technology? Don’t miss the bus: get the ’bus! Includes articles on troubleshooting your PC, installing and setting up computer networks, hard disk drive upgrades, clean installing Windows 98, CPU upgrades, a basic introduction to Linux plus much more. EMC Technologies.....................101 Evatco..........................................92 Futurlec.......................................29 Harbuch Electronics....................43 Instant PCBs..............................103 Price: $12.50 (incl. GST) Order now by using the handy order form in this issue or call (02) 9979 5644, 8.30-5.30 Mon-Fri with your credit card details. Special subscription offer available only while stocks last. Silicon Chip Binders  Each binder holds up to 14 issues  Heavy board covers with 2-tone green vinyl covering  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Investment Technology..............101 Jaycar ................................... 49-56 Kalex............................................83 REAL VALUE AT $12.95 PLUS P & P Mass Electronics..................43,101 Microgram Computers..........3,OBC MicroZed Computers.................101 Oatley Electronics......................IBC Printed Electronics.................... 103 Price: $A12.95 plus $A5.50 p&p each (Australia only; not available elsewhere). Buy five and get them postage free. QualiFi.......................................IFC Just fill in & mail the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. RF Probes.................................101 Questronix.................................101 Rola Australia............................103 R.T.N............................................58 WANTED PERSON WITH EXPERIENCE / APTITUDE able to fault find & repair PCBs – without diagrams. GENEROUS PKG NEG. Tel John<at>AER (03) 9482 4958 0415 305 470. MOTOROLA MC6802P 8 Bit CPU(s) for faulty Signal Generator. Call Shane (02) 9452 2221. WE PAY UP to $60 for contributions to Circuit Notebook. Send your idea to: Silicon Chip Publications, PO Box 139, Collaroy, 2097. Satcam........................................61 Silicon Chip Back Issues.............96 Silicon Chip Binders..................104 SC EFI Tech Special....................95 Silicon Chip Subscriptions...........57 Silvertone Electronics................103 HELP SAVE THE NIGHT SKY! We are losing our heritage of starry night skies. Poor, inefficient outdoor lighting is causing glare and “light pollution”. This wastes energy and increases greenhouse gas emissions. You can help by joining SYDNEY OUTDOOR LIGHTING IMPROVEMENT SOCIETY (SOLIS). SOLIS aims to educate and inform about quality outdoor lighting and its benefits. We also lobby councils, government and other bodies to promote good lighting practice. SOLIS meetings are held third Monday night of each month at Sydney Observatory. Individual membership is $20 pa. Donations are also welcome. Cheques payable to “SOLIS c/- NSAS”, PO Box 214, West Ryde 2114. http://sites.netscape.net/solislp/ 104  Silicon Chip Smart Fastchargers.....................61 Solar Flair/Ecowatch..................102 Tasman Energy..........................101 Truscotts Electronic World...........83 _____________________________ PC Boards Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. GET YOUR OWN PIECE OF THE VIDEO CAMERAS DON’T FORGET The output of these cameras below is std For more details of all of the items SYDNEY2000 OLYMPICS video & can be plugged into the "VIDEO listed in this adand hundreds of IN" socket of any Australian std VCR, other items see our web site video monitor or TV, or via an RF OLYMPIC Modulator to an Ant. Input. The B/W NEW HALOGEN LAMPS Osram brand COLLECTABLES cameras are Infra Red responsive & can 12V 5W $2.50 be used in total darkness with IR SOME THING FOR 12v 20W $2.50 Illumination. THAT SPECIAL 8 O H M 7 5 m m M A G . - S H I E L D E D CHRISTMAS GIFT MONOCHROME CCD VIDEO CAMERA SPEAKERS. WITH AUDIO: B&W Camera built on a SHIRTS, HATS, FLAGS, Foam edged poly cone :2 for $9 PCB with auto iris. (0.1 lux). Can be BACK PACKS ETC. focused sharply down to a JUMBO SERVO KIT...Use it with our CHECK OUT OUR WEB SITE "German Motor" or a motor / gearbox of your choice. This kit is designed to work just like a std R/C servo (with much greater power) using 1-2mS pulse width. It has proportional control ie. if you move the joystick a little, the servo moves a little. It can be used with a std. R/C receiver or with our servo controller kit. Some applications inc... R/C models, Robotics, Gates & Doors, Fly by wire control (with our servo controller) of things like Forward controls for outboards (steering, throttle etc), Pan & tilt of Cameras, Antenna dishes etc. Could be used as a winch for sails etc. with the addition of a multi turn pot & a winch drum. Kit includes PCB, all onboard parts, feedback pot . $35 Add $20 for geared German Motor. DUAL SERVO CONTROLLER KIT This is designed to control R/C servos with 1-2mS pulse with. Ideal for use with our Jumbo Servo kit or with std servos. Applications include testing of R/C servos pan and tilt of cameras etc. Std. kit includes PCB all onboard components, suitable case and pots. $14.... Std. Kit plus power supply suitable for powering 1 Jumbo Servo $24 MICRO SWITCHES 3 mini micro switch assembly on a 600mm cable with a small plug. 3 assemblies for $5 DC MOTOR WITH FEEDBACK: 12-24v starts at 3v. Coil resistance is 13ohms. Body measures 58mm long, 40mm diameter, shaft diameter 4mm, pulley on shaft diameter 8.5mm. The feedback section uses a hall effect sensor with a magnet on the end of the motor shaft. Open collector transistor gives many pulses per. revolution so the speed could be accurately maintained. The motor can be used independent of the feedback: (M44) $7ea or 3 for $17 Some people paid over $1000 for Olympic opening ceremony tickets and received some of the following collectables, here’s your chance to buy a bargain. NATIONAL FLAG TATTOOS Mixed bag of 17 countries inc. GB, NZ, Sweden and more $10 $19 QUALITY BONDS(2pairs) BRAND SOCKS (green on gold and gold on green) FLASHING LED WRIST BAND $8 used 20 x 2 LCD BACKLIT CHARACTER DISPLAY: Each character measures approximately 6mm x 8mm, display area 122mm W x 30mm H. PCB dimensions 151mm wide x 56mm high. Used standard Hitachi chipset (HD44780) mounted on a PCB with LED back-light & dual row 16 pin header: (DL8) $11 or 3 for $27 few mm(useful for people with visual impairment). Spec.: Power req.: 10V to 12V <at> approx. 50mA.CCD: 1/3", 30grams: with 60° $89, with 92° lens: (USED) NETCOMM 56K V.90 MEGA-iMODEM: This modem was used during the Sydney 2000 Olympics. After one minute of cleaning they should appear new. They are in "as new" condition and are supplied with power adaptor and RS232 lead. The drivers can be downloaded from Netcomm: (GMOD56K) $75 P C R E L AY I N T E R F A C E K I T Features include 8 relays (2 are high current contact ratting),Relay “ON” indicating LEDs, onboard relays and DB25 connector. Kit includes PCB, all onboard components and software. $40 ...Optional 5M DB-25 to DB-25 cable:$10 CAMERA INTERFACE KIT This kit provides power for a camera and a RF modulated output for use with TV Ant. inputs. Kit includes case, PCB, all onboard components & therefore modulator.:$18 RADIO CONTROL CLOCK (350mm) As new. These clocks were used by the SOBO during the Olympics. There extremely high accuracy is controlled by a radio signal from the pager network. Settings for all states. Ideal for use in radio stations etc. where time keeping is important. :$250 LIMITED STOCK!!! NEW PC POWER SUPPLIES We have Huge stocks of PC power supplies. Ranging in price from $15 Check our web site for more details Series II Two Channel UHF Remote Control Kit: Two channel encoded UHF PANASONIC KX-TS85ALW PHONES remote control. Has a small key ring style Used for a short assembled period during the transmitter. SYDNEY 2000 Receiver kit Olympics. Too has 5A relay many features contact output to list here, & can be check our web arranged for toggle or momentary site. (KXTS85) $50 each or 2 for $90 operation. 12V DC operation. One transmitter and receiver kit: (K095) $40 60 SEC VOICE RECORDER MODULE This is a small pre-built module and can be Series II One Channel UHF Remote set from 1 long up to 8 short messages. Control Kit: Ref: SC October 97. Has a Features include eight pushbuttons, one switched relay output for operating an for each message. Operates from alarm etc, an indicator output for driving a 6Vdc:$28....Optional speaker $1 buzzer etc, and logic level outputs for 12V DC - 240 AC INVERTER KIT: Features inc. modified square wave & auto start with load sensing. Can be modified for 24VDC. Uses Mosfets with PELTIER DEVICES: minimal heatsinking req. Req. 240V to 8Vsolid state therm0-8V transformer. 200-600 Watt output oelectric cooler / dependant on transformer. Basic kit heater. inc. data, 40 x includes PCB & all on-board components 40 x 4mm.(see our controller below). 4.0A $24... 6.0A $26... including 4 x 60A Mosfets: 8.0A $28 Basic kit inc. PELTIER CONTROLLER KIT: PCB & all This kit is a switch-mode on- board design & correctly controls components: the temperature of peltiers 12VDC SOLENOID PAIR: (K127) $30 to 10A using a very efficient (1)This solenoid pushes a 4mm shaft a design. Kit includes PCB & distance of 2mm. Coil resistance is all on-board components. 8 CHANNEL IR REMOTE CONTROL KIT: 60ohms. Body 29mm long, 22mm dia. The case is not supplied: (K140) $17 This kit converts a Magnavox CD IR (2) This solenoid punches a small 1.5mm diameter hole in a piece of cardboard or KTX PENTIUM II HEATSINK & FAN: remote control, We simply use the housing & 8 keys, & replace the existing paper. Coil resistance is 7ohms. Body Brand new in original transmitter PCB with our PCB. The 34mm long, 40mm diameter: (MA1-MA2) pack with clips & receiver uses an IR RX module tuned to power lead $2.20 pr. 3prs. for $5 38KHz. The output of this simply feeds the terminated with matching SM5032B decoding IC. There a 3 pin plug. are 8 relay outputs, 6 are momentary (HHSP2) $4.50 (output is on only whilst corresponding TX Others available. Check our web site button is pressed) or latching are the last CD CASE two are latching only. TX PCB measures KEYPAD: Matrix style with a 7 pin Don’t buy 2 CD 89 x 30mm and RX PCB measures 140 x connector. The metal buttons very rugged. collections, one for the 94mm. The PCB & all on-board compLooks like ones used in public phones. car and one for your onents (inc. Dimensions 70mm wide by home just make your eight output 79mm high. 10mm square collection portable. relays on the buttons. This keypad would This case is rigid receiver) are be very suitable for security with a soft touch supplied to applications due to it's outer. Holds 24 CDs build both TX & rugged construction: $12 RX kits: (GKP1) $3.50 3 for $9 (K065RT) $50 operating a CENTRAL LOCKING KIT. 12V DC operation. Comes with a ready made transmitter with two pushbuttons (lock, relay on unlock, relay off), and a receiver PCB and all on-board components. 5 LEDS make for easy tuning and diagnostics: (K096) $30 LOOK Fused cig. lighter leads with LED indicators 10 for $2 Heavy duty fused cig. lighter leads 5 for $2 KEYBOARD STOW AWAY New in original box.place your PC case on top of these units and your keyboard slides in and our on rails. $14 We have too much test equipment. we need to clear some to make way for more. Check out our web site Great bargains at a fraction of the new cost. If it’s not on our web site then ring us. www.oatleyelectronics.com Orders: Ph ( 02 ) 9584 3563 or 64, Fax 9584 3561, sales<at>oatleyelectronics.com, PO Box 89 Oatley NSW 2223 major cards with ph. & fax orders, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 SC_MAR_01