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SILICON CHIP NOVEMBER 2006 PRINT POST APPROVED - PP255003/01272 8 $ 50* NZ $ 9 90 BUILD YOUR OWN INC GST INC GST RADAR SPEED GUN Measures speed of moving objects! FREE with th issue*:is MULTIPATTERN SIMPLE PIC CHRISTMAS STAR TO BUILD siliconchip.com.au November 2006  1 *Australi a only SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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 Contents Vol.19, No.11; November 2006 SILICON CHIP www.siliconchip.com.au Features    8 Review: Sony Alpha A100 Digital SLR Camera Sony’s new 10-megapixel black beauty has the goods – by Barrie Smith 16 Review: JVC KD-AVX2 Car Entertainment System A complete entertainment system in a DIN-sized package – by Julian Edgar 68 Review: Bitscope BS310 Mixed Signal Oscilloscope It packs a digital oscilloscope, logic analyser, data recorder and waveform generator into one affordable package – by Peter Smith Sony Alpha A100 10-Megapixel Digital SLR Camera – Page 8. Pro jects To Build 26 Build A Radar Speed Gun, Pt.1 Easy-to-build Doppler speed radar system can read directly in km/h or mph for speeds in excess of 250km/h – by Jim Rowe 34 Build Your Own Compact Bass Reflex Loudspeakers Ready-to-assemble with Peerless & Vifa drivers; you decide the final finish – design by Aaron Waplington 41 Programmable Christmas Star Hundreds of pre-programmed patterns, high-brightness LEDs, twinkle effects and light enough to hang on your Christmas tree – by David Meiklejohn 76 DC Relay Switch For High-Current Loads Build A Radar Speed Gun, Pt.1 – Page 26. Want to switch power to a high-current load using a circuit capable of supplying just a few milliamps? This device is the answer – by John Clarke 80 LED Tachometer With Dual Displays, Pt.2 Completing the construction, tips on installation and adjusting the default software settings to suit your car – by John Clarke 88 PICAXE Net Server, Pt.3 Controlling a simple motor-driven device via the Internet – by Clive Seager Special Columns 48 Serviceman’s Log So hopelessly devoted to you – by the TV Serviceman 62 Circuit Notebook Build Your Own Compact Bass Reflex Loudspeakers – Page 34. (1) Wiegand Decoder; (2) Electronic Combination Lock; (3) Model Train Detector; (4) Picaxe To LCD Interface; (5) Picaxe-Controlled Yoghurt Maker 72 Salvage It! Using the convex lenses from car headlights (bike light) – by Julian Edgar 96 Vintage Radio Radio Corporation’s WS108 military transceiver – by Rodney Champness Departments   2   4 61 94 Publisher’s Letter Mailbag Order Form Product Showcase siliconchip.com.au 104 Ask Silicon Chip 107 Notes & Errata 110 Market Centre Programmable Christmas Star – Page 41. November 2006  1 SILICON CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Editor Peter Smith Technical Staff John Clarke, B.E.(Elec.) Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Reader Services Ann Jenkinson Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Julian Edgar, Dip.T.(Sec.), B.Ed, Grad.Dip.Jnl Kevin Poulter Mike Sheriff, B.Sc, VK2YFK Stan Swan 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, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $89.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. Fax (02) 9939 2648. E-mail: silicon<at>siliconchip.com.au Publisher’s Letter Do people really want a high-performance valve amplifier? This month’s Mailbag kicks off with a letter which is a plea for a high-quality valve amplifier. This particular reader has evidently done a lot of background research and knows many of the issues involved. And while I can understand some of the attractions of valve amplifiers – those glowing filaments and all of that – I wonder whether enough readers would build such an amplifier if we did go ahead. It might be like some other projects we have done in the past where we have had people seemingly very keen to become involved in an ambitious design, only to lose all enthusiasm when confronted with a complicated kit and a reasonably large outlay of money. For example, it is one thing to say you would like to see a 500W amplifier in the magazine and quite another to go out, buy the kit and build it, when it finally appears in the magazine. So let’s flesh out this high-performance valve amplifier concept. First of all, let’s define high performance, in the valve context. If we do design a valve amplifier, it will need to deliver a total harmonic distortion of around 0.1%; or preferably .01%. That means we will be using negative feedback; in fact we will probably use “nested feedback” and lots of it, with a pushpull output stage. That concept will probably turn off more than half of the valve amplifier aficionados, since they have swallowed the nonsense from some hifi magazines that all feedback is anathema. Secondly, the amplifier will need to be very quiet, in order not to audibly degrade the signals from compact disc and DVD players. We are not likely to be able to achieve the extremely low residual noise of our best SILICON CHIP solid-state designs but we would want to do better than -90dB if possible. Third, we want to go for an output of 50 or 60 watts per channel. Anything less is really not enough with many of today’s relatively low efficiency loudspeakers. And why labour long and hard, and lay out a lot of money, to produce a valve amplifier which produces significantly less output. So that’s the broad concept, with no circuit details, no potential valve list for people to salivate over and nothing else to look forward to other than it would be a “valve” amplifier rather than a “soul-less” solid-state design. That it would be a lot more expensive than a far superior solid-state design delivering lots more power is beyond doubt. How much money? I am guessing but it is likely to be the wrong side of $1000.00. Now the question is: how many readers would go for it? 10? 30? Maybe 100? Without some indication that a reasonable number of people would want to build such an amplifier, the idea just won’t get to first base. If not, well it won’t upset us. Our inclination is to upgrade the popular 15W class-A amplifier which we featured in 1998. So if you really would like to see a 60W/channel valve amplifier (with feedback!), drop us an email. Leo Simpson ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip siliconchip.com.au Performance on-the-move Strength in the palm of your hand Say hello to the next generation of Agilent Technologies; the new handheld digital multimeters and oscilloscopes NEW U1250A series handheld DMMs place versatility at your fingertips! that are built to test and designed to save. • 50,000 count resolution, dual displays and innovative new features and over-mould casing for Featuring built-in battery charging capability, exciting • Unlimited data logging from DMM to PC protection in the toughest conditions. • Programmable square wave generator If you need a test instrument that offers the ultimate • Temperature, Capacitance, Maths functions portable test capabilities, Agilent’s range of handheld • 20MHz frequency counter digital multimeters and oscilloscopes are the right choice. NEW U1600A series handheld scopes bring high performance on the move! Redefining Feature-Rich Portability with the New Handheld Series • Scope-DMM-Recorder - all-in-one • 4.5-inch LCD colour display View an online demo: • FFT, Zoom and Math functions www.agilent.com/find/U1250A_showcase • 200MSa/s sampling rate • 125kB/ch memory depth www.agilent.com/find/U1600A_showcase Go to www.agilent.com.au/find/quotation, select your instrument and click a button to get a quick quote and our online tools will deliver a formal quotation to your email Australia 1800 629 485 New Zealand 0800 738 378 www.agilent.com/find/U1250A www.agilent.com/find/U1600A address in 2 minutes. Agilent Technologies MAILBAG Plea for high-quality valve amplifier Having recently started a book on amplifier design, I have reviewed a large number of circuits ranging from the original Williamson to your single-ended parallel 6L6 hybrid of August 2005. Although I glanced at your design initially, I didn’t take it in until now. I accept that, from the objectivist point of view, valve amplifiers are not capable of the accuracy and economy of the best solid-state designs. People who use valve amplifiers do so regardless of cost or inconvenience: Audio Research and Conrad-Johnson (among others) sell the biggest and most satisfying tube amplifiers at premium prices although they also produce solid-state models which are, on paper, a more practical proposition. The Williamson is probably the most famous circuit of all time. It was not simple or cheap but a vast number were built in various forms. At the same time, Baxandall published a cheaper circuit which was ignored as far as I can determine. A decade later Baxandall published an even cheaper design which cost slightly less than the (by then established) Mullard 5-10 but produced lit- Nuclear power can be fragile I just read your “nuclear” editorial in the July 2006 issue. For anyone who has implicit faith in nuclear reactors, we had an experience in Cape Town to keep one on the edge of one’s seat. One of two nuclear generators in the city was (apparently) sabotaged and was out of commission. As a result, the city drew too much power and the whole nuclear power station went down. Now, either the nuclear power station needs to keep going or it needs to draw power from elsewhere, to avert nuclear melt-down. So they diverted power from the north of the country. That overloaded the 4  Silicon Chip tle more than half the power. This also sank without trace. The clear inference to be drawn is that for at least 60 years, people have been custom-building amplifiers to get better sound quality than that obtainable off the shelf. Since it is now possible to buy highly linear amplification for less than a dollar a watt (in the form of a 5.1 home-theatre receiver), one must ask why anyone would want to build their own amplification. The answer is obviously still “to get better sound quality than that obtainable off the shelf”. While conceding that the sweetest recorded sound I can recall was (smallscale, limited frequency range) music from vinyl on a single-ended EL84 (pentode) stage, I must implore you, in order to maintain Australia’s excellent audio tradition (Benson, Thiele, Small, Langford-Smith, Cherry, et al) to publish at least one quality valve amplifier as a reference. I would suggest an upgraded Mull­ ard 5-20 configuration to get the advantages of zero unbalanced DC in the output transformer primary and cancellation of even-order nonlinearity (and ripple) in the output stage. Since class-A operation is desired, cathode-bias can be used and if more than 30 watts per channel is grid, so that went down, too. The third and final line of defence was three large diesel generators, which they powered up. However, as I understand it, diesel fuel production was dependent on the nuclear power station! My insurer, with amazing rapidity, posted a nuclear exclusion clause to all its clients. They got the power station fixed eventually with the help of the French (it’s called Koeberg – it might well be on the internet). Thomas Scarborough, Cape Town, South Africa. Comment: it sounds as though the country’s electric grid is not very robust if it cannot withstand the loss of one power station. required, paralleled output devices can be fitted, facilitating even better output DC balance with a negligible drop in open-loop gain. The EF86 input stage (and its partition noise) could well be replaced by a cheaper and easier to obtain 12AX7 configured as a DC-feedback pair. The open loop gain and linearity of the whole amplifier would easily allow for a closed-loop sensitivity of 500mV with 30dB negative feedback, resulting in THD of well under 0.1% at 30W (or 60W with four output devices). The amplifier needs to be affordable, but not cheap in any sense, and certainly not below contemporary standards for acceptable audio quality. Anything less would be a bad joke which could rebound on Australia’s international audio reputation. Maybe I’m overlooking some important point but I can’t see how a parallel single-ended output stage can possibly compare with a push-pull stage in any way other than in the elimination of the phase-splitter (this being the excuse given in a circuit for an “economy” radiogram published in NZ about 50 years ago!). Roger Lowry, via email. Error in home theatre article I am a subscriber to the magazine and I noticed the following apparent errors in the “Home Theatre Video Projector Survey” article in the August 2006 issue. On page 14, in the paragraph titled “Scanning method”, the text states: (1) “On your television set, half the lines (called a field) are displayed 50 times a second (Hertz) and then the other half are woven in at 50 times per second. . .” (2) “In PAL we have two interlaced siliconchip.com.au ‘Moon Shots were faked’ idea came from USA First let me say that your Publisher’s Letters and the Maibag section are, like the rest of SILICON CHIP, always stimulating. But now let me say that this month’s (October) ‘PL’ deserves a small “oops”. I don’t know if your bias is of the ‘fixed’ or ‘self’ varieties but it was very evident. The US has many good things about it but it also has many bad! One of these is its apparent need to infect other cultures with its mores. Where do you think the ‘Moon shots were faked’ idea came from? 50Hz displays or 25 complete pictures in each second”. This did not seem right and after much thought the first statement is incorrect. With 625-line TV signals, the first field of a frame occurs at 25 per second in a time period of 1/50th of a second (the odd lines). The second field takes the next 1/50th of a second (the even lines), to give a frame rate of 25 frames per second – as the second quote states. Thus to be correct, the first statement should read “On your television set, half the lines (called a field) are displayed in a 50th of a second and then the other half are woven in during the next 50th of a second . . .” David Williams, Hornsby, NSW. Tips on restoring 78 RPM discs I was very interested in the article in the September 2006 issue of SILICON CHIP, detailing ways of re-mastering LPs and removing the various forms of surface noise inherent in them, while transferring them to CD. I began tinkering with this sort of thing after reading a SILICON CHIP article about seven or eight years ago, describing a program called DC-Art (or Diamond Cut 32) which was designed for audio restoration. My interest was in restoring a very large library of 78 and 80 RPM recordings which I had accumulated over the years and I bought a copy of DC-Art, then a later version, DC Millennium (1999), then DC5 (2002) and finally, DC Live 6 in siliconchip.com.au A quick look at the net will show you that, like the Christian right’s ideas about religion and “Intelligent Design”, the evangelists for this crazy idea come from the USA itself. We are now so attached to that culture, that a large number of otherwise intelligent people believe anything that vocal folk from that country tell them. Mind you, blaming the extreme left (with all its faults), when the real culprits promoting these things in the USA seem to be more aligned to the right, will not help. Bruce Bowman, via email. 2004. Each program is a big advance on the one before. As an example, DC6 has a 20-band graphic equaliser with some invaluable pre-sets, compared to the 10-band equaliser in Millennium and DC5. I note that John Clarke describes using Nero 6 and its Wave Editor for removing noise from LPs and it certainly does that very successfully with 45s and LPs. I have tried using Wave Editor in Nero 7 Premium to clean up 78s but I find that DC6 is more flexible for these older discs – not only giving greater control but also providing a valuable group of presets which make the job easier. In addition, DC6 has a major advantage for someone working with 78 and/ or 80 RPM discs, in that it has a speed conversion effect which allows a 78 to be played at 45, or even 33, RPM into the computer hard drive; and then to be converted to 78 speed – invaluable when it is so difficult to buy a 78 turntable these days. Even better, DC6 has a fine-tuned pitch-control, which recognises that many 78s and 80s were recorded at speeds varying by 2 RPM or so, either way. I use an ancient but still functional Dual 1019 4-speed turntable, so I don’t need the speed conversion but the pitch control in DC6 has improved a number of discs which are “off-speed” even further than the mechanical speed variation on the turntable can correct. Some of the old discs have been loved to death but it’s amazing how Atmel’s AVR, from JED in Australia JED has designed a range of single board computers and modules as a way of using the AVR without SMT board design The AVR570 module (above) is a way of using an ATmega128 CPU on a user base board without having to lay out the intricate, surface-mounted surrounds of the CPU, and then having to manufacture your board on an SMT robot line. Instead you simply layout a square for four 0.1” spaced socket strips and plug in our pre-tested module. The module has the crystal, resetter, AVR-ISP programming header (and an optional JTAG ICE pad), as well as programming signal switching. For a little extra, we load a DS1305 RTC, crystal and Li battery underneath, which uses SPI and port G. See JED’s www site for a datasheet. AVR573 Single Board Computer This board uses the AVR570 module and adds 20 An./Dig. inputs, 12 FET outputs, LCD/ Kbd, 2xRS232, 1xRS485, 1-Wire, power reg. etc. See www.jedmicro.com.au/avr.htm $330 PC-PROM Programmer This programmer plugs into a PC printer port and reads, writes and edits any 28 or 32-pin PROM. Comes with plug-pack, cable and software. Also available is a multi-PROM UV eraser with timer, and a 32/32 PLCC converter. JED Microprocessors Pty Ltd 173 Boronia Rd, Boronia, Victoria, 3155 Ph. 03 9762 3588, Fax 03 9762 5499 www.jedmicro.com.au November 2006  5 Mailbag: continued they clean up once you get the hang of using the program. John notes in his article that the RIAA curve built into most preamps is not suitable for 78s and this becomes very clear when you try using a standard amplifier preamp to boost the signal between pickup and sound card. For a start, the bass is overwhelming and emphasises the rumble built into many old recordings. While DC6 has a frequency-variable rumble filter which can deal with this, it’s better not to have it there in the first place because of the way it loads up the signal. So I have tried what I am told is a controversial technique, recommended by tracertek.com, who are involved with the DC products. They market a small preamp which amplifies the signal from the pickup without equalisation and I have found, particularly on 80 RPM and very old 78s, it works very well. Their suggestion is to record to the hard drive, unequalised, and then use the playback correction curves provided in DC6 to introduce whatever equalisation works best with that particular record. I am not a technical person and friends who are far more expert than I have questioned the use of this preamp, 6V to 12V car radio conversion I refer to the September 2006 “Ask SILICON CHIP” item regarding changing a 6V car radio to 12V. I remember doing this about 40 years ago. Three things need to be done. The first, as M. S. says, is to get a 12V vibrator. The next is to get out the valve data books and check the heater currents for all the valves and work out the best matching arrangement to connect the heaters in a series/parallel circuit across 12V. The third is to rewind the vibrator transformer primary. I was fortunate with this as the transformer laminations came apart quite easily and the transformer winding had not been varnished too heavily. Normally, the primary is wound on the outside so the secondary doesn’t need to be 6  Silicon Chip saying it will introduce distortion, because its output is too high and will overload the sound card. I have not experienced distortion or apparent overload when using the preamp but I must admit the unequalised sound really is weird to listen to. However it comes good after finding the right equalisation and in the end produces pretty good results to the CD. I have several 78 pickup cartridges, which give some variation in stylus size, to match the variations in groove diameter found in old records. But the cartridge that works best for me is an Ortofon OM78. It tracks beautifully at 2g or less and seems untroubled by warped records although DC6 even has a way of correcting these. John Tingle, Port Macquarie, NSW. Comment: using a high-gain unequalised preamp running from a low battery supply risks signal overload from the cartridge on loud music passages, although it may not overload the sound card input. Historical TV sets I have a Rank Arena C-2251 (NEC Chassis) that is still working although the blue gun is a bit weak. I would like disturbed. My memory of vibrator circuits is a bit hazy but I think the primary is centre-tapped. The aim is to change the turns ratio, so after counting the turns as the original primary comes off, half the turns need to go back on and I seem to remember using a slightly heavier gauge wire. I was fortunate when I did this as I was working in a workshop that did motor winding at the time. Bill Adams, via email. Comment: unfortunately, your meth­od would be too involved for most restorers as they would not have access to valve data and would not be able to rewind a vibrator primary. The 6V regulator method has the virtue of simplicity and requires no modifications to the radio. to be rid of it but it seems a shame to destroy a small piece of Australian TV history (especially as it still works). If anybody would like it they would be very welcome to it. I am in Adelaide. Please contact me at researchnurse<at>iprimus.com.au LPG production in Australia is well in excess of demand I read with interest your Publisher’s Letter on natural gas in the September 2006 issue and hope to clarify some of the information you cited about LPG. The Federal Government subsidy for LPG conversion is expected (based on industry estimates) to result in around 80,000 installations by the end of 2006 and up to 120,000 installations per annum during 2007 and 2008, then moderating in subsequent years. Over the life of the grant scheme to 2014, it is estimated that around 750,000 vehicles will be fitted with LPG, leading to over 1.25 million vehicles being LPG-fuelled. Also, the factory-fitted LPG vehicles that are eligible for a smaller grant could add a further 250,000 LPG vehicles by 2014. That would mean a significant proportion of motorists – over 1.5 million vehicles (10% of the car park) would have access to LPG, resulting in a saving of some three billion litres of petrol and further reducing Australia’s reliance on imported crude oil and refined fuel. LPG in Australia is produced from extraction from “wet” natural gas or from the refining of crude oil. Over 80% of the Australian LPG production comes from the “wet” gas extraction process and only around 20% is sourced from the refineries. Major naturally occurring LPG production sources include North West Shelf, Bass Strait and Cooper Basin. Australia currently exports around 3 billion litres of LPG and this is forecast to grow to over 4 billion by the end of 2008 on the back of further developments in natural gas production. ABARE has forecast a significant surplus of LPG to 2020 and the likelihood that supply will exceed demand for around 50 years. While CNG is also a resource that could and should be used to further reduce our vehicle fuel reliance, it does siliconchip.com.au have some issues in smaller vehicles. CNG passenger vehicles are used in the US and Europe and have been trialled here in Australia but their wider use has been hampered by the lack of infrastructure. Only about 25 public refuelling facilities exist in Australia compared to the 3240 LPG outlets amongst the 6500 service stations. Range is another issue and most CNG passenger vehicles are only capable of 200-250km before refuelling is required. Home refuelling devices are being used in the US but can take up to 16 hours to refuel a completely empty tank. This would be OK for a vehicle that’s used to travel from the suburbs to the city and back again each day but would not be suitable for inter-city use. Installing a large volume CNG refuelling facility (required for public use) is also costly because of the high compression and storage requirements, meaning a cost of around $500,000 plus per site. Recovering these costs on each cubic metre of CNG sold can add a significant amount and reduces the overall CNG benefit. The leasing and operating cost of a home refuelling unit could also result in a similar benefit reduction. Efficiency when running a vehicle on CNG is also reduced compared to petrol and requires additional timing modules to be installed or other modifications to bring performance up to a similar level. Ford trialled a CNG Falcon wagon some years back but this required engine modifications, including increased compression ratios and ignition timing requirements. This car also needed two under-floor tanks and one large tank mounted behind the seat to give a range close to petrol. This option did not receive much consumer support and so was scrapped. CNG has similar qualities to diesel and with reasonably minor modifications, can deliver a similar outcome, which is why most CNG trials have been with larger diesel vehicles and in particular government-owned urban buses. These have been combined with depot-based refuelling infrastructure to deliver reasonable outcomes. A number of trials are now concentrating efforts on using LNG stored in cryogenic cylinders in heavy vehicles, as these have extended ranges. If these siliconchip.com.au Better circuit for suppressed zero meter In “Ask SILICON CHIP” in the September 2006 issue, a correspondent (P. F.) asks for an expanded scale voltmeter. In my estimation, your answer is useless! While the zener diode works by suppressing the zero as stated, it also works as a very good thermometer. A much better system to use, if you want repeatability, was described in “Circuit Notebook” in the June 1995 issue. The only point not mentioned in that article is that the tabs of the 7805/7905 should be thermally bonded together. The only other components required are two ferrite beads on the supply rails if the voltmeter is being used near any transmitter. Tests I have done show no change in meter reading if the regulators are placed in melting ice water and are successful and if vehicle manufacturers support such developments, then a number of freight carry vehicles could be switched to natural gas. As these vehicles can consume up to 55l/100km, this would be a significant additional saving on diesel use but infrastructure still needs to be developed. The Federal Government had a scheme in place previously covering half the refuelling site cost but only a few took up the offer. At this stage LPG is still in my opin- then removed and placed in boiling water! I have been using this system since (I think) the mid-70s, not long after 3-terminal regulators become available. Secondly, on page 95 of the same edition (September 2006), some poor beginner IS going to kill a perfectly good meter by connecting it up as an ammeter as described! For an ammeter to continue to read the current (repeatably) as calibrated, it must have four separate connections to the shunt: two on the outside ends for the high current, and two separate connections for the voltage (Low/Meter current) connections. Wal Douglas, Marian, Qld. Comment: you are right – the June 1995 circuit is a good solution but we had long forgotten it. Here it is again. ion the only “readily available” fuel alternative but I would like to think that Australian ingenuity will overcome the barriers to the use of CNG, LNG and other alternatives to petrol and diesel use in the near future. More information on LPG is available at our web sites: www.lpgaustralia. com.au and www.lpgautogas.com.au Phil Westlake, Industry Development Manager, LPG Australia. www.lpgaustralia.com.au November 2006  7 As production of film cameras continues to shrink, it comes as no surprise to see the electronic ‘majors’, such as Sony and Panasonic, grasp an opportunity to feed the swelling demand for digital single lens reflexes, known to the in-crowd as DSLRs. Barrie Smith reports his experience with the Sony Alpha A100 camera. Sony’s new 10-megapixel Black Beauty 8  Silicon Chip siliconchip.com.au T he advent of the Sony Alpha A100 was signalled well in advance with a torrent of chatter in the tech press. Then it was shown to Australian journalists both in Japan and North Queensland; however, it was some weeks before production models began to do the rounds. At first sight, the A100 looks like an SLR. Pick it up and it feels like one, with most of the controls where you’d expect them but ardent fans of film SLR cameras will be dismayed to find it doesn’t always work like an SLR! The camera is solid, with a magnesium-alloy front cover panel and bottom plate mounted onto a diecast magnesium front chassis. With battery and memory card loaded and with the f3.5-5.6/18-70mm Sony lens attached to the A100, the scales register 790 grams, so carrying it on a trip would not be a great burden. Oversize A3 Specs-wise, the camera is well up to market expectations, packing 10.2 million pixels onto its CCD. If you size your images at 225 dpi (dots per inch) for printing, its maximum image size of 3872 x 2592 pixels will give you a 44 x 29cm print. The A100 uses interchangeable lenses, a factor which explains the enthusiasm evident in the Sony and Panasonic camps for the DSLR sell-on factor – you can never have enough lenses! Viewing is via an optical reflex finder turret (just like an SLR) or via The 23.6 x 15.8mm Sony Super HAD (hole accumulated diode) CCD chip – at 10.2 megapixels it’s not the biggest around these days (see last page!) but it is significantly larger than many of its competitors. the generous rear 6.4cm LCD screen which also acts as your gateway to the menu options. The CCD area is 23.6 x 15.8mm, similar to the APSC film format (0.66 of the 35mm film frame’s area) while the BIONZ image-processing engine uses an RGB primary colour filter. With an APS-C sized CCD area, a lens that is nominally 50mm in focal length (35mm SLR-speak) is actually 33mm. When using Maxxum/Dynax lenses this shrinking factor has to be taken into account; telephotos get longer, wide-angles become narrower. Control The arrangement of external controls is a little different to other cameras but easily grasped in a shooting situation. Viewed from behind, the power switch is at the left edge. Above it is a function dial which gives you direct access to ISO speeds (up to ISO 1600), white balance settings, D-Range optimiser, colour mode selector, auto and manual focus mode, flash and metering modes. A tiny button in the centre of the function dial fires up the rear LCD screen, giving access to the options. Now some explanations need to be made. D-Range optimiser: There are three choices: off, adjust image brightness and contrast of a scene, optimise contrast and colour. These two tweaks appear to vary the dynamic range of an image; using either will add about half a second to the camera’s imageprocessing time. Each is a short cut for those unwilling to fiddle with images in software. Colour mode selector: This alters the ‘colour space’ of the camera, in other words, tunes the colour tone/white balance/contrast/saturation/sharpness that best suits your subject. Each setting can make your pictures either more vivid (greater colour saturation in skies, greenery etc), improve portraits (enhances skin tones), landscape, sunsets, night views or create a black and white rendering – and there’s Adobe RGB. If you’re not going near any imageediting software, choose any of the above except for Adobe RGB. If you are going to Photoshop your pictures later, set the camera to Adobe RGB. Focus modes: This offers settings for Sony realises that buying the A100 camera body is only the first step: there is a very large after-market for lenses and accessories – and has catered for it, with much more promised! siliconchip.com.au November 2006  9 At left is a close-up of the Sony Alpha’s lens mounting arrangement with the lens itself above. Photographers used to the KonicaMinolta A-type mount may recognise that it’s identical – in fact these lenses can be used with the Sony Alpha. single-shot auto focus, continuous AF and manual focus. The focusing area can also be specified, from a 9-zone grid to spot AF. Metering modes: Exposure determination can be made via a 40-segment matrix, from a centre-weighted area or a central spot reading. On the right side of the camera, on the top deck you will find the mode dial. Here you can select auto operation, Program auto, aperture and shutter priority, manual shooting plus a number of scene selection presets (portraits, sports, sunset, landscapes, night portraits, macro). Sprinkled across the camera’s top surface and rear panel are buttons to access the on-screen menu, preview stored images, a delete facility, single frame and continuous shooting options (up to six shots at 3 fps), an exposure lock and a manual exposure over-ride. Immediately behind the lens on the camera’s body is a 2-position slide that switches from manual to auto focus. While viewing the rear screen, most options are selected via a 4-way rocker and central confirmation button. The shutter button is in its natural position over to the far right on the camera’s top surface. Directly in front and barely 5mm from the shutter button is the control dial. At this point you need to view the bright array of settings through the optical reflex turret viewfinder and vary the lens aperture (f stop) while staying with a fixed shutter speed or vice versa – otherwise known as aperture and shutter priority. Here’s the back and top of the Sony Alpha A100 to show the main controls. While most of the controls are easy to operate and reasonably self-explanatory, I found the control dial and shutter button too close – I continually changed settings without wanting to. I guess in time that would be less of a problem. 10  Silicon Chip siliconchip.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.mgram.com.au Specifications: Sony Alpha DSLR-A100 Sensor: ............................... 23.6 x 15.8mm interline interlaced CCD. Pixel Count: ........................ 10.2 million effective pixels. ADC: ................................... 12-bit. Image Sizes: ....................... 3872 x 2592; 2896 x 1936; 1920 x 1280. Image Formats: .................. RAW, RAW+JPEG, JPEG (fine and standard). Lens Mount: ....................... Sony Alpha (also compatible with Minolta A-type bayonet lenses) Anti-shake Effect: ............... Equivalent to 2-3.5 f stops in shutter speed. Anti-Dust: ........................... Charge protection coating on low-pass filter and CCD-shift mechanism. Auto Focus: ........................ TTL CCD line sensors (9-points, 8 lines with centre cross-hair sensor). Predictive focus control for            moving subjects. Auto-tracking focus point display. AF area selection: ............... Wide AF area; spot AF area (centre); focus area selection (any of 9). Focus modes: ..................... Single-shot AF; direct manual focus; continuous AF; automatic AF; manual focus. Shooting Modes: ................ Auto; Program AE (with shift); aperture and shutter priority AE; manual. Scene Modes: ..................... Portrait, landscape, macro, sports, sunset, night portrait. Sensitivity: .......................... Auto, ISO 80/100/200/400/800/1600. Metering Modes: ................ Multi-segment (40 segment); centre-weighted; spot. Shutter Speeds: .................. 30-1/4000 second, Bulb. Flash X-sync: ...................... 1/160 sec; 1/125 sec (with Super SteadyShot on). Flash Modes: ...................... Auto; fill flash; red-eye reduction; wireless/remote off-camera flash; rear curtain flash sync; high speed sync; slow sync with AE lock.. speed sync; slow sync with AE lock. Flash range at f 2.8: ............ 1.4-8.6m. Colour Space: ..................... sRGB, Adobe RGB. Viewfinder: ......................... Eye-level fixed pentaprism. LCD Monitor: ...................... 6.4cm (230,000 pixels). Drive Modes: ...................... single-frame, continuous (RAW: 3 fps, up to 6 frames total. RAW+JPEG: 3 fps, up to 3 frames. JPEG: 3fps, unlimited).. JPEG: 3fps, unlimited). Interface: ............................ USB 2.0; AV output (PAL/NTSC); DC input; remote terminal. Storage: .............................. Compact Flash Types I/II; Memory Stick Duo/Pro Duo via CF adapter; Microdrive. Power: ................................ Rechargeable lithium-ion rechargeable battery; AC adapter (optional). Dimensions: ....................... 133 x 95 x 71mm. Weight (body only):............. 545 grams. Supplied Accessories: Strap, body cap, USB and AV cables, battery charger, rechargeable 7.2V/11.5Wh lithium-ion battery, Memory Stick CF adaptor, CD-ROM of software (Picture Motion Browser (Windows), Image Data Converter SR (Windows/Mac)). Prices: ................................ Body only - $1499. Body and 18-70 mm lens - $1749. Body plus 18-70mm and 75-300mm lenses $1999. Body plus 18-70mm and 75-300mm lenses $1999 Distributor: ......................... Sony Australia 1300 720 071 or www.sony.com.au/dslr I found the proximity of the control dial to the shutter button to be annoying. The dial’s knurled surface often fell naturally to a probing forefinger when I was searching instead for the shutter button. And why in heaven’s name is the shutter button black, small and nearly flush with the surface of the camera body? The A100 accepts CompactFlash Types I and II as well as Memory Stick Duo cards and Microdrive, the latter sliding into the same slot via a CF adaptor. Neither card is supplied with the camera, a perfect lever for you to pressure the sales assistant in hammering down the overall purchase price. RAW format Experienced and discerning digital 12  Silicon Chip photographers have embraced the use of the RAW format in recent times. Without question it’s the best way to head in the quest for superb digital images; JPEG just isn’t in the race. As you shoot with the A100, you have the option to write the images to the memory card as RAW files solo, RAW files plus matching JPEGs – and as JPEGs only in two qualities. To unpack the RAW images is a separate, post-shoot chore in software. Photoshop CS2 will do it and let you save the image as a Digital Negative (Adobe’s DNG format), as a JPEG, TIFF or Photoshop native file. A CD in the camera kit carries Sony’s Image Data Converter SR application which works in similar fashion and saves an image as a JPEG, TIFF or in the native SR format. Both applica- tions display a tri-coloured histogram to give you a graphic representation of RGB brightness levels. If you want to move forward in this digital picture business RAW is the only show in town. When you shoot the original picture is saved as RAW data, with no presets such as the prevailing colour temperature, colour balance etc locked in. When converting a RAW file to a TIFF or JPEG for a later touch up in editing software you have access to contrast, brightness, shadow levels, saturation, exposure. Image metadata is also saved in RAW. You can access data on the lens used at the time of the shoot and its f stop, shutter speed, exposure mode, time of day as well as other parameters. siliconchip.com.au Some cameras, especially the upper end compacts, will chew up time in writing RAW files to the card. The A100, with a hefty built-in buffer swallowed the RAW images with no complaint. I shot pictures two at a time as quickly as I could hit the button, the buffer slowing down only after each pair; in continuous mode the three frames per second speed was a revelation. The speed is even more surprising when you consider that the maximum image size of 3872 x 2592 pixels can represent a RAW image of anywhere between 9 and 12MB, paired with a JPEG that varied between 3-5 MB. Vive la differences! Digital SLRs use the familiar turret viewfinder that takes an optical split from the reflex mirror before the image hits the CCD. Ideal for viewing and even manual focusing, it’s a bright, clear display, viewable in bright sunlight. The rear LCD screen is used only for viewing your captured shots and can suffer from washout in bright conditions. This is possibly the biggest shock for newcomers to DSLR technology. With the recently released Olympus E-330 DSLR, you can view your subject matter before and during shooting, via a ‘live’ display on the rear LCD screen. This is a first and will be welcomed by digital newbies who have become accustomed to viewing a live image on the LCD in their $300 digi compacts. So the Sony A100 is still back with the rest of the gang; the turret finder is Sony’s RAW application – Image Data Converter SR – which converts images to TIFFs, JPEGs etc. Range of control over the image’s contrast, brightness, shadow levels, saturation, exposure and much more is extreme. used for viewing and shooting while the rear LCD is only for post-shooting evaluation. There is one bright note: the camera kicks off the AF action as soon as you look through the viewfinder. Simply bring your eye to the finder and the focus system starts working away. It also works if you move your finger close to the eyepiece! Carrying the camera body carelessly could also easily trigger the AF system into battery-sapping action! Steady on A relatively weighty camera that wears a longish lens cries out for an image stabilising system, preferably an optical one. With Super SteadyShot Sony has carried over Minolta’s excellent anti-shake approach that operates by mounting the CCD on a base that constantly moves in opposition to movement of the camera body itself. The major benefit is that there is no need for each lens to be stabilised, as in other camera systems. Sony claims that you can wind down the shutter speed by anywhere between a factor of x2 or x3.5. In other words, a best-case scenario would let you shoot and capture sharp shots at 1/150th of a second instead of 1/500th, using the digital equivalent of a 500mm lens. There is an indicator in the view- Two Into One Do Go Until a few years ago mergers in any sector of Japanese industry were rare occurrences. But global economic shifts have forced many companies to face hard facts and join the enemy or better still, swallow them! In January 2003, Konica and Minolta merged. Both had fine reputations for camera and lens design and manufacture. Both had entered the digital camera market and failed. They hoped the merger “could propel them into the big league of office machine makers.” What a come down! But as time wore on, neither Minolta nor Konica were able to leverage their strong brands in film photography into the hotly competitive digital camera market, dominated by Canon, Sony and Olympus. The merger came at an opportune time for Sony, ambitious to proceed with DSLRs but lacking street cred in the photo market: the company was recognised as a premium maker of CCDs for its compact siliconchip.com.au digicams but was forced to buy in Zeiss lenses to give it a marketing advantage. July 2005 saw Sony and Konica-Minolta agree to jointly develop DSLRs. Sony would make the imaging sensors and the internal processors while the other entity would deliver its acknowledged camera design skills, along with their optical and lens mount prowess. Minolta possessed considerable eminence in the latter as well as excellent anti-shake technology built into the camera body, not each individual lens, like Canon and Nikon’s models. Sony of course has immense skills in product planning and manufacturing. The result is that the new line of Sony DSLRs incorporate the Konica-Minolta lens mount system and anti-shake functions. The cameras can accept Konica-Minolta optics as well as a special prestige line of lenses manufactured by Zeiss in Japan. November 2006  13 finder of how steady the camera is held while shooting. No more dust problems Dust is a big bugbear with DSLRs if you need to constantly fit and refit lenses in hostile environments. With the A100 a special indium tin oxide anti-dust coating on the CCD reduces static charge build-up which repels dust particles from its surface. Like the Olympus system, the CCD also activates high-speed vibrations that dislodge particles each time the A100 is powered on or off. Believe me, an anti-dust system is an essential for a DSLR! Accessories Three screen menus for the Sony Alpha A100. The top allows you to set the auto focus zones, centre the ISO and the bottom sets Adobe RGB paramaters (for Photoshop users). In typical SLR fashion, once you buy a camera the next step is to furnish it with a brace of accessories and Sony has not missed a trick to feed this appetite. There is a range of compatible flashes and lighting systems that attach to the camera’s hot shoe. Suitable for use on-body or off-camera, two flashes are available in Guide Number 36 and 56 output power. There’s also a Macro Twin Flash with adjustable arms and a ring light for ultra close macro shooting. Lenses? Heaps of ’em, from macros to a 16mm (35mm SLR equivalent) fish-eye to a 500mm mirror lens as well as a bunch of zooms, the longest drawing a 35 SLR equivalent of 18-200mm. Tele and wide angle converters? Yes. The camera will accept lenses from the Maxxum/Dynax lens mount system. At this stage there is also small group of high performance, high ticket Carl Zeiss lenses, two examples of which each exceed the cost of the A100’s camera body. End notes Sony has done its homework, without doubt but it would not have created the fine camera it has without the Konica and Minolta heritage. The review camera was delivered with the 18-70mm zoom and knowing that budget optics sometimes lack a little in the distortion department, I checked it for this problem. I was not surprised to find that the wide end of the zoom produced barrel distortion at the image edges and pincushion distortion at the tele end. This is par for the course for this level of lens and of concern only to those who shoot a lot of rectilinear subjects, like stamps, documents, framed paintings and similar. The picture quality is beyond reproach for a DSLR at this price level. Shooting with the RAW format I pulled some remarkably sharp, naturally colour images, quickly, with no fuss. What more could you ask? There is little in the A100 that would concern committed photographers, either in the control layout or ergonomics. It’s an SLR – of the digital kind! And a very well executed one at that! SC That’s not a camera. THIS is a camera! While this article was in production our attention was drawn to this as-yet unreleased Seitz D3 6 x 17 panoramic camera which offers a 160 megapixel resolution. Yes, you read that correctly: 160 megpixels. That’s 7500 pixels vertical and 21,250 pixels horizontal (compare that to the Sony Alpha above). This results in an uncompressed file size of about 950MB. And it can capture 300MB in just one second (think how long it takes your PC to copy a 300MB file!) With an ISO/ASA range of 500 to 10000, the Seitz D3 has 48-bit colour depth. Its preview screen is 640 x 480 pixels – the largest colour camera screen yet on the market and can 14  Silicon Chip allow in-camera previewing, editing, zooming and image control without having to download to a computer. When the Seitz D3 is released in January next year, it will be available in both mobile (!) and studio models. And the price? Glad you asked! It will set you back around $50,000 give or take – and remember, you’re still going to have to add a lens or twenty. And with a camera of this impressive quality, you’re going to want a Schneider or Rodenstock (which Seitz recommend) or some other $$$$$$$ model! Oh yeah: don’t forget a big memory card. The old 512MB just won’t quite cut it – though the camera does have a 16MB flash memory for preview pics. siliconchip.com.au siliconchip.com.au November 2006  15 JVC KD-AVX2 Revolutionise your in-car music If you’ve had the suspicion that despite the publicity surrounding amplifiers, subwoofers, split speaker systems and all the rest, incar entertainment advancements of late have been sadly lacking, well, you’re not alone. In fact, apart from the major advance of MP3-reading CD players and stackers, it’s easy to think that not much has happened. Until now. A DVD movie is easily viewable by a front seat passenger and a second screen can be added for rear passengers. 16  Silicon Chip siliconchip.com.au Review by Julian Edgar W F ith the release of JVC’s KD-AVX2, there’s now a single DIN-sized package that’s quite extraordinary. irst-up, it’s a conventional AM/FM radio MP3-compatible CD – except it looks better than most after-market units with its black ‘piano’ finish and the lack of garish silver highlights and vacuum fluorescent displays that seem to afflict so many head units these days. Second, there’s a built-in 3.5-inch colour LCD screen. This means that not only are all the menus able to be displayed in large writing against contrasting backgrounds, you can play and view DVDs – yes, the KD-AVX2 is also a DVD player. (And before you wonder at the use of that, the KD-AVX2 can also run a second larger screen, eg, for back-seat kids – so you can use the head unit to easily monitor what’s showing on their screen.) In addition, the inbuilt LCD can show the picture from a reversing camera, automatically selecting the camera input when you place the car in reverse gear! Finally – and get this – the KD-AVX2 can play MP3 files recorded on DVD. You can literally have your whole music collection on a few DVDs able to be stored in the glove box! Add to this a built-in 4-channel amplifier, a huge number of inputs and outputs (including line level audio and subwoofer), a remote control and an almost intuitive ease of use and you’re looking at what’s simply one of the most impressive bits of car audio/video gear we’ve ever seen. Not only is the JVC KD-AVX2 an AM/FM radio, MP3 compatible CD player and DVD player with built-in LCD screen, but it can also play MP3 encoded files burnt to DVD! That makes for a complete audio-visual entertainment unit, all in a standard DIN-sized enclosure. The background wallpaper can be varied – this is the sunset. LCD Screen It’s easy to be dismissive of the small colour LCD – isn’t it much too small to be viewable? The answer to that is: not in most cars. The car in which the pictured installation occurred placed the unit 70cm from the driver’s eyes. That’s similar to viewing my 69cm (diagonal) lounge room TV at 4 metres instead of the 3 metres at which I normally view it – no big deal. This promotional JVC graphic really makes the point: from CDs with (say) 16 songs, to MP3-encoded CDs with 100 songs, to a “giga MP3” DVD with 1000 songs. Even at the highest MP3 sampling rates and with long songs, you’re still looking at 500 or more songs on one DVD – that’s more than 30 albums. Not enough? Well, just burn another MP3 DVD and put it in the glove box! siliconchip.com.au The number of set-up functions is surprisingly large. As shown here, the output levels of each speaker can be set on a plus/minus 1dB basis. A white noise tone that moves from speaker to speaker is generated during this process. The faceplate motors into a horizontal position for disc insertion and ejection. The faceplate can be removed for security and motor-driven to three different angles for better viewing. November 2006  17 intuitive in use and many of the buttons are rarely needed. In fact, for the driver, the remote is near useless. However, rear passengers can use it to control the DVD playback when they’re watching the DVD on a second screen. In use about the only downer of the KD-AVX2 is that when CD/DVD is selected, it takes a full 30 seconds before the disc starts to play. Set-Up Menus It might look like there’s lots of connections but these are just the line level inputs and outputs! The connection flexibility of the JVC KD-AVX2 allows it to function as a standalone AM/FM/CD/DVD/MP3 player or work with additional amplifiers, audio-visual inputs and LCD screens. Note the vent for the cooling fan at right. The display is also very sharp and bright. There are no problems reading any written data (eg, track numbers, the time, set-up menus etc) and even when a front seat passenger is viewing a movie, visibility for them is quite acceptable. And the advantage is that the LCD fits within the single DIN package – you don’t need to use a large motorised screen that, in its extended position, will almost certainly cover dashboard air vents or controls. The KD-AVX2 features a dual-zone DVD facility, where rear passengers can view a second screen and listen to the audio on headphones while front seat passengers listen to the radio or another audio input. The screen can be motor-driven to three different angles, cancelling reflections and allowing the unit to be mounted low on the dash while still retaining good visibility. A large number of set-up menus are provided. Amongst other attributes, these allow you to: • Separately adjust the brightness of the LCD when disc or AV input are selected • Change the ‘wallpaper’ background colour of the LCD (this is a surprisingly effective and useful option – especially because as the unit is relatively plain, it allows the switched-on appearance to be changed across a range of style and colours to suit personal taste) • Alter whether file tags (eg, MP3 song titles) scroll once or continue to scroll • Set the clock for 12 or 24-hour display • Adjust the speaker size settings (small, large or none) for each of the possible six speaker outputs • Adjust the distance to each of the four main speakers from 15 to 600cm in 15cm steps • Adjust the individual speaker levels in 1dB increments (a white noise test tone is provided during this set-up) • Select from nine preset equalisation curves or 3 useradjustable curves (however you cannot tie the equalisation curve to a source [eg, radio] like you can with some systems) • Adjust the volume of each source separately so changes in the master volume control position aren’t needed when selecting a different source • Adjust subwoofer line level output including level, high pass filter and crossover point (80, 120 or 150Hz) • Alter amplifier gain to limit power output when using low power speakers. All these are easy to set, however it should be noted Operation For many people, the KD-AVX2 will be the most complex piece of car audio-visual gear they’ve ever used – that’s certainly the case for this reviewer. However, despite having numerous set-up menus and possible adjustments, the unit is very straightforward. The main controls consist of two 4-way pushbutton knobs. With these you can select the source (eg, radio or DVD/CD), adjust the volume and select different radio stations or tracks and albums. At the four corners of the faceplate are four pushbuttons. These turn the unit on/off, adjust the angle of the faceplate, eject the CD/DVD (the whole faceplate motors forward to 90° to reveal the slot) and detach the faceplate for security. Additionally, there are four small pushbuttons that are used to alter rarely adjusted parameters. The system works very well, with the most commonly used controls the most easily accessible. A remote control is also included. However, in contrast with the head unit, the remote has 36 buttons, many of which have dual functions. The remote control is much less 18  Silicon Chip Unlike the head unit, we found the remote control hard to use. However, it is useful for controlling the DVD playback if the head unit is working in dual mode, where rear seat occupants can watch a DVD and listen on headphones while those in the front listen to the radio. siliconchip.com.au that two of the menus (Disc Setup 1 and Disc Setup 2) can only be accessed when a disc is selected as the source and for Disc Setup 2, when play has been stopped. Why this is required (rather than being able to select these menus whenever you want) is not clear and is one of the very few control system glitches. Both the input sources (eg, “rear vision camera”) and the radio stations (eg, “ABC News Radio”) can be titled. The title can comprise upper and lower case letters (and also numbers) and while it’s time-consuming to put in a lot of titles, again the procedure is straightforward. Versatility The KD-AVX2 can play CDs with MP3/WMA recorded on CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RW, DVD+R, and DVD+RW discs. (And of course it can play normal old CDs too!) The four-channel in-built amplifier has a claimed output of 20W RMS per channel at 0.8% THD. Clearly, if you want to listen at high undistorted levels through inefficient speakers, you’ll need one or more external amplifiers. Line level outputs are provided for front left, front right, rear left, rear right, centre and subwoofer. The centre speaker output is included because the KD-AVX2 can provide 5.1-channel sound with Dolby Digital, Dolby ProLogic II and DTS processing. The KD-AVX2 is standard DIN size in width, depth and height (182 x 52 x 160mm) but it uses a slightly higher than standard (55mm) faceplate. In this respect many other DIN radios are the same but this is a dimension to check in your car before buying. So that the faceplate can perform its motorised gymnastics for disc insertion and variable viewing angles, the front of the unit is designed to protrude slightly further forward than a conventional radio. Mass is 1.9kg – again about par for the DIN course. An internal fan vent means the rear of the unit should not be butted up flush against a surface. Conclusion We’ve left the best to last. Considering that the KD-AVX2 replaces an AM/FM radio, in-dash CD stacker, DVD player and small monitor LCD screen, adds sophisticated set-up and display features and has the unbeatable ability of playing back DVDs of MP3 songs, the recommended retail price of $1199 seems positively cheap. But it gets even better: such is the retail competition in this day and age that at the time of writing, you can buy the KD-AVX2 for $789 plus postage from reputable (ie, have excellent feedback records) sellers on eBay. SC And in fact, that’s just what this reviewer did… IS IT LEGAL TO WATCH DVDs IN A MOVING VEHICLE? Our interpretation of the Australian road rules suggest that it is not legal in any state to install a video screen where it can be seen by the driver, unless that screen is being used for navigation purposes or as a driver’s aid (eg, as a reversing monitor, etc). It is possible to wire the KD-AVX2 so that it cannot display while the vehicle is in motion but that rather defeats its purpose. In a nutshell, the driver must not be able to view the screen at all if it is showing any form of entertainment. siliconchip.com.au “MERLIN” Safe External Switchmode Power Supply Practical and Versatile Mini Broadcast Audio Mixer Broadcast Quality with Operational Features and Technical Performance identical to full sized Radio Station Mixing Panels Permanent Installation is not required, the “Merlin” is as easy as a Stereo System to “Set Up”,all connections via Plugs and Sockets The “Merlin” originally designed for Media Training use in High Schools and Colleges is a remarkably versatile Audio Mixer Applications: Media Training - Basic Audio Production - News Room Mixer - Outside Broadcasts - Radio Program Pre Recording On-Air Mixer in small Radio Stations - “Disco Mixer” The “Merlin” is an Affordable Professional Audio Product Buy one for your School, College, Community Radio Station, Ethnic Radio Broadcast Association or for yourself For Details and Price, please contact us at ELAN Phone 08 9277 3500 AUDIO Fax 08 9478 2266 2 Steel Court. South Guildford email sales<at>elan.com.au www.elan.com.au Western Australia 6055 Silicon Chip Binders REAL VALUE AT $13.95 PLUS P&P Issues Getting Dog-Eared? Keep Your Copies Safe With These Handy Binders Price: $13.95 plus $7.00 p&p per order (buy five and get them postage free). Available only in Australia. Just fill in the handy order form in this issue; or fax (02) 9939 2648; or ring (02) 9939 3295 & quote your credit card number. Silicon Chip Publications, PO Box 139, Collaroy 2097. November 2006  19 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: dicksmith.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: dicksmith.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: dicksmith.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: dicksmith.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: dicksmith.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: dicksmith.com.au Build Your Own Radar Speed Gun, If you’re into any kind of racing – like cars, bikes, boats or even horses – this project is for you. It’s a microwave Doppler speed radar system, similar to the expensive gear used by traffic police, only much cheaper. It can read directly in km/h or mph for speeds up to 250km/h+. MOST OF US ARE familiar with the radar speed guns used by traffic police to detect speeding motorists. If you’ve been caught speeding yourself and have had to pay a hefty fine, you probably don’t want to know any more about them. But if you’re a car or bike racing enthusiast, you may well have wanted one of them yourself, so you could measure the speed of cars or bikes. In these articles we’re going to show 26  Silicon Chip you how to build a Radar Speed Gun of your own – for much less than the cost of a professional unit. It can measure the speed of cars, bikes, horses, runners or even boats with a bit of ingenuity. It’s compact and light in weight, can read directly in either km/h (kilometres/hour) or mph (miles per hour), and operates from 12V DC. There’s also a hold switch to enable you to freeze the reading. The system is in two parts. There is a microwave head unit in a small shielded box which is mounted on the underside of a cylindrical antenna housing made from two 500g coffee cans joined end-to-end, to form the radar gun assembly. This is linked by a cable to a counter/display unit housed in a UB1 jiffy box. How it works First of all, to get a good undersiliconchip.com.au How Doppler Speed Radar Works Pt.1 By JIM ROWE Fig.1: the basic principle behind a Doppler radar speed gun. standing of the basic principles of Doppler speed radar, please read the explanation and look at the diagram in the accompanying panel. Once you have that under your belt, you will be siliconchip.com.au When an ambulance, fire engine or police car is speeding towards you with its siren going, the frequency (or pitch) of the siren sounds higher than its actual frequency. That’s because as the vehicle is moving towards you, it tends to “catch up” with the sound waves – effectively compressing them. Then when the vehicle is speeding away from you, the frequency of the siren sounds lower than its actual frequency, because the movement of the vehicle is now effectively stretching the sound waves. This is the so-called Doppler Effect, named after Dutch physicist Christian Doppler who first explained it around 1842. This principle is used to measure the speed of cars, bikes, boats and other vehicles by Doppler speed radars, such as the radar guns used by traffic police to detect speeding motorists. The basic idea is shown in the diagram of Fig.1. The radar gun is fixed in position and transmits a narrow beam of microwave radiation (with frequency Fo) towards the moving vehicle. This outgoing radiation propagates towards the vehicle at the normal speed of electromagnetic (EM) radiation in air – at 299,792,458m/s (metres per second); ie, the same as the speed of light (c). Because the vehicle is moving towards the radar gun, the effective frequency of the microwave beam it “sees” is a little higher than Fo. In fact, it’s actually Fo + (Fo . v)/c where “v” is the vehicle speed. This is the frequency of the microwave signal reflected from the vehicle, back towards the radar gun. When this reflected signal is detected by the microwave gun, its frequency is higher again by the same amount (because it is being effectively transmitted by the moving vehicle). As a result, the frequency of the reflected microwave signal returning to the radar gun is given by: Fr = Fo + 2(Fo . v )/c In the radar gun, the reflected signal is heterodyned with the outgoing microwave signal, which generates the difference frequency between the two. This difference frequency is given by: Fd = Fo - [Fo + 2(Fo . v)/c]     = 2(Fo . v)/c    = v(2Fo/c) This is the Doppler frequency and it is directly proportional to the vehicle speed. For example, if we use a microwave frequency of 2.45GHz, the Doppler frequency turns out to be 16.34 times the vehicle speed in metres/second. So if the vehicle is travelling at 60km/h, which is 16.6m/s, the Doppler frequency will be close to 271Hz. If the vehicle is moving away from the radar gun instead of towards it, the reflected microwave signal returning to the radar gun has a frequency which is lower than the outgoing frequency by exactly the same amount. So when the two are heterodyned together in the radar gun as before, the Doppler frequency is exactly the same. The radar gun is therefore able to measure the speed of the vehicle quite accurately by feeding the Doppler frequency to a counter. This counter can be made to indicate the speed directly in km/h (or mph) by adjusting its timebase or gating time to allow for the scaling factor of 2Fo/c. November 2006  27 Fig.2: this diagram shows the circuit blocks used in the Radar Speed Gun. It consists of two main sections: a microwave head section and a counter & display section. ready to follow the block diagram of the project itself, shown in Fig.2. As you can see, the microwave head section has a small UHF oscillator to generate a low-power continuous microwave signal with a frequency of 2.45GHz (2450MHz). This signal is then passed through a UHF amplifier, to achieve a power level which is still low but sufficient to give the unit good Doppler range and sensitivity. The amplified 2.45GHz signal (Fo) is then fed out to the microwave antenna, which is just a very small 1/4-wave “whip” inside the coffee-can gun barrel. The 2.45GHz energy radiated from the antenna is then directed out of the open end of the barrel, towards the vehicle we wish to measure. Microwave energy reflected back from the vehicle returns down the barrel to the antenna and is received as a signal with a frequency Fr which will be higher or lower than the outgoing 2.45GHz signal, depending on whether the vehicle is moving towards the radar gun or away from it. This received signal Fr is then fed into a mixer along with the original signal Fo. As a result, the mixer’s output contains the difference between Fr and Fo (ie, either Fo - Fr or Fr - Fo). This is the Doppler signal, which is quite low in amplitude but its frequency is directly proportional to the vehicle’s speed. It is then passed through a simple audio amplifier stage (the Doppler preamp) to boost it in level before sending it down the cable to the counter/display section. In the counter/display section, the Doppler signal is amplified and passed through an LP (low-pass) filter and then converted into a train of narrow pulses to give it a digital waveform. Its frequency is then measured and displayed on the 3-digit LED readout. The counter’s gating signal is derived from a 38kHz crystal oscillator via a frequency divider chain, programmed to produce the correct gating time to compensate for the Doppler Fig.3: the microwave head section uses a 2.45GHz oscillator based on transistor Q1. This drives a microstrip line, after which the signal is amplified by IC1 and fed to the antenna. The reflected signal is first fed to a mixer stage D1 to produce the Doppler signal and this is amplified by transistor Q2 and fed to pin 3 of CON1. 28  Silicon Chip siliconchip.com.au Parts List Microwave Head Unit 1 PC board, code DOPPLR1a, 51 x 64mm (EC8194) 1 piece of 0.3mm brass sheet, 89 x 76mm, for shield box 2 500g instant coffee tins, 129mm diameter x 173mm long (with one plastic cap, see text) 1 35mm length of 1.25mm diameter copper wire 1 ADCH-80A broadband RF choke (RFC1) 1 PC-mount type A USB connector, (CON1) Semiconductors 1 ERA-2SM wideband UHF amplifier (IC1) 1 BFP182T UHF NPN transistor, SOT-143 package (Q1) 1 PN100 NPN transistor (Q2) 1 1PS70SB82 UHF Schottky diode, SOT-323 package (D1) 1 1N4148 diode (D2) Capacitors 1 220mF 16V RB electrolytic 2 1mF 25V tantalum 4 10nF multilayer monolithic ceramic 5 10nF X7R ceramic, 1206 SMD package 1 1nF COG ceramic, 1206 SMD package Resistors (0.25W carbon composition, 1% unless specified) 1 1.5MW 1 470W 2 10kW 2 100W 1 1kW 1 100W 0805 SMD package frequency/speed scaling factor – and thus give a readout directly in km/h or mph. The divider programming is normally set for a gating time of 220ms which gives a readout in km/h. But if a readout in mph is needed instead, three short tracks on the display PC board can be cut and three alternative links fitted to change the divider programming for a gating time of 137ms. Microwave head circuit Now that you have an overall view of what happens inside the Radar Speed Gun, let’s work through the siliconchip.com.au Counter/Display Unit 1 PC board, code DOPPLR2a, 84 x 148mm (EC8195) 1 UB1 Jiffy box (158 x 95 x 53mm) 8 PC pins 1 mini rocker switch 1 35 x 53mm piece of red perspex sheet 4 25mm long M3 tapped spacers 4 6mm long M3 countersink head machine screws 4 6mm long M3 round head machine screws 1 38kHz mini quartz crystal (X1) 1 PC-mount type A USB connector (CON1) 1 PC-mount 3.5mm stereo socket (CON2) 1 PC-mount 2.5mm concentric DC connector (CON3) 4 14-pin DIL IC sockets 4 16-pin DIL IC sockets 1 USB Type A to Type A cable Semiconductors 3 FND500 common cathode LED displays (DISP1,DISP2,DISP3) 1 LM324 quad op amp (IC1) 1 4093B quad Schmitt NAND gate (IC2) 1 4027B dual JK flipflop (IC3) 1 4553B 3-decade counter (IC4) 1 4511B BCD to 7-segment decoder (IC5) 1 4069 hex inverter (IC6) 1 4020B 14-stage binary counter (IC7) 1 4073B triple 3-input AND gate (IC8) 3 PN200 PNP transistors (Q1,Q2,Q3) 1 PN100 NPN transistor (Q4) 1 1N4004 silicon diode (D1) 1 1N4148 signal diode (D2) Capacitors 1 2200mF 16V RB electrolytic 1 220mF 16V RB electrolytic 2 100mF 16V RB electrolytic 2 47mF 16V RB electrolytic 3 10mF 16V RB electrolytic 6 100nF multilayer monolithic ceramic 1 100nF MKT metallised polyester 2 47nF MKT metallised polyester 1 22nF metallised polyester 1 10nF metallised polyester 1 4.7nF metallised polyester 1 3.3nF metallised polyester 1 2.2nF metallised polyester 2 1nF metallised polyester 1 330pF disc ceramic 2 27pF NPO disc ceramic Resistors (0.25W, 1% unless specified) 1 2.2MW 0.5W carbon film 1 1MW 2 4.7kW 1 330kW 3 1kW 6 100kW 7 680W 4 47kW 1 470W 2 22kW 1 100W 4 10kW 2 47W 1 6.8kW 1 2kW horizontal trimpot (VR1) Where To Buy A Kit This project was sponsored by Jaycar Electronics and they own the design copyright. Kits will be available from Jaycar stores and dealers. Features & Specifications • A compact handheld Doppler speed radar system operating on a frequency close to 2.45GHz. Range is 200+ metres for a family sedan. • Can be set to read directly in kilometres/hour (km/h) or miles/hour (mph), to over 250km/h. • • • • • Resolution is 1km/h or 1mph with an accuracy of around 1%. 2.2 measurements/sec for km/h, or 3.6 measurements/sec for mph. Measured speed is displayed on a 3-digit LED display. Hold switch lets you freeze the reading. Operates from 12V DC, current drain around 130mA. November 2006  29 circuit diagrams to give you a more detailed insight. First, we’ll look at the circuit of the microwave head section – see Fig.3. The 2.45GHz oscillator is formed by the circuitry around Q1, a BFP182T NPN planar UHF transistor. This comes in a very small SOT-143 surfacemount package and has a transition frequency (ft) of over 5GHz, making it suitable for an oscillator operating at 2.45GHz. Here we use it in what is 30  Silicon Chip essentially a Colpitts circuit, with the oscillation frequency determined by the microstrip line connected to the collector. A small amount of 2.45GHz energy from the oscillator is coupled into a second microstrip line running close by and parallel to the collector line. This coupled energy is then fed to the input of IC1, which is a Mini Circuits ERA-2SM wideband UHF amplifier in a very small “pill” SMD package with four leads (two of which are grounded). Boosting the signal IC1 provides a gain of about 12dB, boosting the 2.45GHz signal to the right level for feeding to the antenna. Pin 3 of IC1 is both its output pin and its power supply pin. DC power is fed to it via a 100W bias resistor and RFC1, a special UHF choke. The amplified RF energy is coupled out via a 10nF siliconchip.com.au Fig.4: the counter and display circuit. The incoming signal from the head unit is amplified and filtered using op amps IC1a-IC1d and the resulting signal then used to drive the frequency counter section (IC4, IC5 & the three 7-segment displays). IC6b, crystal X1, IC7, IC8 & IC3 form the 38kHz oscillator and timebase divider circuit for the counter. capacitor, to a third and quite short microstrip line, which takes it to the antenna. The antenna is a 30mm length of 1.3mm copper wire attached to the end of this third microstrip line, positioned at the correct point inside the Radar Gun’s coffee-can barrel to ensure that the 2.45GHz energy is radiated away in a reasonably narrow beam. The microwave energy reflected from the moving vehicle re-enters the siliconchip.com.au barrel and reaches the antenna, which now acts as a receiving antenna. So a small amount of this reflected energy passes back down the antenna feed microstrip line, where it enters mixer diode D1, together with some of the original 2.45GHz energy from IC1. D1 is a 1PS70SB82 Schottky diode in a very small SOT-323 SMD package and with very low capacitance, making it suitable for use in UHF mixers. Here its mixing action results in the Doppler difference frequency appearing across its 1kW load resistor, with all of the UHF signals and mixing products conducted to earth via a 1nF bypass capacitor. The Doppler audio signal from the mixer is then coupled via a 1mF capacitor to the base of transistor Q2, a common emitter amplifier stage. The amplified Doppler signal appears at the collector of Q2 and is coupled via a second 1mF capacitor to November 2006  31 The microwave head section is built onto a small double-sided PC board. This mounts vertically under the barrel assembly with its antenna protruding into the cavity. This is the prototype counter & display board. The full construction details are in Pt.2. pin 3 of CON1, a USB Type A connector used to mate with the cable linking the microwave head with the counter/ display section. The same cable is used to provide the microwave head with +7.5V DC from pin 2 of CON1. Counter/display circuit Fig.4 shows the counter/display circuit. As shown, the Doppler signal from pin 3 of CON1 is first fed to a lowpass filter stage based on op amp IC1a. 32  Silicon Chip It then passes to IC1b, which is a noninverting amplifier stage with a fixed gain of 101 times, as set by the 1MW and 10kW feedback divider resistors. The amplified Doppler signal from IC1b then passes through a high-pass filter stage based on IC1c, to filter out any low-frequency noise which may still be present. The output of IC1c is basically an amplified and cleaned-up version of the Doppler signal, which is now sent in two directions. One is via the 6.8kW resistor to a headphone driver stage using transistor Q4, which allows you to monitor the Doppler signals with a pair of headphones if you wish. This can help in aiming the radar gun at the particular vehicle or object whose speed you want to measure. The second and main path of the Doppler signal from IC1c is to the input of IC1d, which provides further gain. IC1d’s gain can be adjusted from about 20-220 times using trimpot VR1. This allows you to adjust the sensitivity of the Radar Speed Gun, depending on whether the object being measured is close or further away. From IC1d, the boosted Doppler signal is passed through a passive lowpass filter formed by a 10kW resistor and 10nF capacitor, and is then fed into a pulse-forming circuit based on Schmitt NAND gates IC2a and IC2b. The signal emerges from pin 4 of IC2b as a train of narrow (300ms) negativegoing pulses of the same frequency but with an amplitude of about 11.4V peak-to-peak. This “digital” version of the Doppler signal becomes the input for the frequency counter section and can also be monitored using an oscilloscope at test point TP3. The frequency counter is based on IC4, a 4553B 3-decade BCD counter with built-in output latches and display multiplexing. It is coupled to three 7-segment LED displays via IC5, a 4511B BCD-to-7-segment decoder which drives the displays. siliconchip.com.au The digit select outputs from IC4 (pins 2, 1 & 15) are used to turn on each display digit at the correct time via driver transistors Q1, Q2 & Q3. As noted earlier, the counter’s timebase signals are derived from a 38kHz crystal oscillator. The oscillator uses IC6b, part of a 4069 unbuffered hex inverter. Two sections of the same IC (IC6d and IC6c) are used as buffers for the 38kHz clock signal, one to drive the programmable timebase divider and the other to drive test point TP1. The timebase divider is IC7, a 4020B 14-stage binary counter, together with triple AND gate IC8 (a 4073B), used for reset gating to achieve the desired division ratios. Links LK1-LK3 can be used to change the division ratio between 4185:1 (for readings in km/h) and 2601:1 (for mph). The three links are short tracks on the PC board for default readings in km/h, relevant to users in Australia and New Zealand. To change the divisor settings over for readings in mph, simply cut the tracks under the PC board and fit jumper shunts or wire links in the three “mph” link positions instead. Whichever setting has been select­ ed, the timebase pulses from the divider can be monitored at test point TP2. For the default km/h setting, the pulses at TP2 will have a frequency of 9.0778Hz, while for the mph setting, they’ll be at 14.6103Hz. The timebase pulses are used to toggle the two flipflops in IC3, a 4027B dual JK flipflop. The two flipflops are cascaded and, along with gates IC2c and IC2d, run as a simple sequencer for controlling the counter. The output of IC3a is used directly to control the clock input of IC4 (pin 11) and also to gate the Q-bar output of IC3b via IC2d to produce the latch enable signal for IC4 (pin 10). The LE A plastic dust cap fits over the end of the barrel assembly to keep out debris and protect the microwave “whip” antenna. signal transfers each count into IC4’s output latches at the end of each gating period. The output of IC3a is also used to gate the Q output of IC3b via IC2c, to produce (after differentiation) a reset pulse for IC4’s counters (pin 13). The frequency counter therefore runs continuously in a count/latch enable/reset cycle at a rate of 2.2 measurements per second for km/h readings or 3.6 measurements per second for mph readings. The Hold switch to freeze the reading grounds the “K” input (pin 11) of IC3b to disable the flipflop and hold the present reading in the counter. The complete circuit operates from 12V DC and this is applied to the counter/display unit via connector CON3. The total current drain is about 130mA. You can use a pack of eight series-connected C-size alkaline cells or a small 12V sealed lead-acid (SLA) battery like the compact 1.3Ah unit sold by Jaycar as SB-2480. The latter will run the Radar Speed Gun for about 10 hours on a single charge. Construction The construction details are all in Pt.2. Note, however, that the Jaycar kit will not include the two coffee cans that are used to make the Radar’s antenna barrel. So you might want to visit your local supermarket to buy a couple of cans of el-cheapo instant coffee. If possible, get one can with a push-on plastic cap, because this comes in handy as a dust cap for the open front end of the antenna barrel. Alternatively, the plastic top of a bulk CD container can be used as a dust cap, although it won’t be as tight a fit SC as a cap supplied with a can. WIN ME! Commence a new subscription (or renew an existing one) between now and Christmas and you’ll go in the draw to win a pair of these superb M6 bass-reflex kit speakers, valued at $599 – as featured in this issue – courtesy of theloudspeakerkit.com See page 61 for full details siliconchip.com.au SILICON CHIP www.siliconchip.com.au November 2006  33 Ready-to-assemble, compact, high quality speakers – you decide the finish! M6 KIT LoudspeakerS Would you like to build some high quality speakers and don’t mind doing some enclosure assembly finishing? These M6 compact bass reflex systems from theloudspeakerkit.com could be just what you are looking for. Use them on stands or on a bookshelf. Design by Aaron Waplington* 34  Silicon Chip siliconchip.com.au T he speakers are based on a 6-inch woofer from Peerless Acoustic Engineering, teamed with a silk dome tweeter from Vifa in Denmark. Each kit has a pair of woofers and tweeters, with assembled 2-way crossover networks, plastic tuned ports, bonded acetate fibre (BAF) wadding and precision cut and routed panels of MDF (Medium density fibreboard) to make two enclosures. The two drivers are high quality units which are well matched in sensitivity and overall balance and will make a very good pair of speakers in an average-sized listening room, either as stereo pair or as the front speakers in a home theatre system. They can be used as bookshelf speakers or be mounted on stands which, like the kits themselves, are available from theloudspeakerkit.com In more detail, the woofer is a 165mm (6.5-inch) unit with low-loss synthetic rubber roll and a double magnet system to provide magnetic shielding. The tweeter is the Vifa D27TG4506, a 27mm silk dome unit with a ferrofluid-damped voice coil. It is not magnetically shielded. This means that you will not be able to use the finished speakers in close proximity to CRT video monitors. + 2.7Ω 8.2 µF – FROM AMPLIFIER L1 560 µH D27TG4506 TWEETER 18Ω + – – Fig.1: the crossover network has impedance equalisation for the woofer (22W + 6.8mF). Note the tweeter polarity: it is reversed, as shown in this diagram. 22Ω – 10 µF + L2 560 µH The 2-way crossover network provides attenuation slopes of 12db/ octave for both the woofer and tweeter. Crossover frequency is 2.5kHz. Both the inductors are air-cored, meaning that distortion due to any core saturation will not occur. The 8.2mF tweeter coupling capacitor is a polypropylene type while the woofer crossover capacitors are bipolar electrolytics. The circuit of the crossover is shown in Fig.1. As noted above, the finished cabinets are quite compact, measuring 440mm high, 200mm wide and 295mm deep. Rated frequency response is from SG-18 WOOFER 6.8 µF 40Hz to 20kHz at the –3dB points, as depicted in the graph of Fig.2. Efficiency is 88dB/1W<at>1m, while the recommended amplifier should be in the range from 20 to 100W per channel. Nominal power handling is stated as 90W, for music signals. The nominal system impedance is 8W and the impedance curve, as shown in Fig.3, is typical of a bass reflex system with the double hump at low frequencies. How do they perform? If you are used to listening to large tower speakers it will be quite a surprise to hear how much sound these The kits are supplied complete – enclosure panels, drivers, crossovers, ports, wadding . . . even screws. You need to supply some PVA glue and a Phillips-head screwdriver. siliconchip.com.au November 2006  35 The speaker enclosures (and crossovers) are designed around these specific speaker drivers – Vifa “silk dome” D27TG4506 tweeters and Peerless SG-18 woofers (one of each per enclosure). They are a good match for each other. M6 loudspeakers can deliver. They have an extended bass down to around 50Hz and midrange is quite smooth. At the high frequency end, the silk dome tweeter is very sweet and particularly good on strings. One point which should be mentioned about these kits is apparent in the photographs – they are not supplied with grille cloth frames. This may not be a problem in most households but if you have young children you will want to make sure they are well out of reach of little probing fingers or other implements! Apart from the kits are complete, right down the screws, gold-plated terminals and plastic tuning ports. You won’t need your soldering iron either, because all connections are push-on terminals. Oh, you will need some PVA glue and a screwdriver. The speaker kits are covered by a 7-year warranty and a 14-day money back guarantee. So a client can purchase a kit and then has 14 days to build the kit and listen to them. If they are not satisfied with their purchase then they will get a refund of their money. Assembly It is up to you to assemble and glue the panels together to make the boxes and then finish them in timber veneer, paint or whatever. We chose to glue all the panels together in one fell swoop. It is easier to do, provided you have sufficient clamps to do the job. The alternative, gluing panels together in sequence, means that you have top be absolutely sure that each 36  Silicon Chip panel is exactly at right angles to its neighbour; otherwise the panels will not fit. Once you have all panels clamped, wipe off any excess PVA glue while it is still wet. Once dry, it is virtually impossible to remove and you will have to sand any excess flat – which spoils the very smooth finish of the panels. We left the boxes to dry overnight. Then we used a special router bit to machine a 5mm radius on all the corners. This removes the very sharp edges on the panels and the end result looks better. This is of course optional. Finishing the enclosure. As noted on the LSK website, there are a number of different options for finishing your enclosures and this must be done before the drivers and crossovers are assembled into the boxes. We elected to paint our prototypes, using a high gloss, oil-based enamel. We started by using an all-purpose acrylic primer after having thoroughly sanded off all the rough edges. We also used an acrylic filler to fill the inevitable fine gaps in the joins between the panels. We used a 50mm brush to apply the primer and the finish coat. Big mistake. It is impossible to get rid of the entire brush stroke. We learnt by doing! After thoroughly sanding it all back, we then used a 50mm foam roller to apply the finish coat. This gives much better results and while you won’t get the glass-smooth finish that is attainable with a spray gun, it is much quicker and easier. The slightly dimpled finish from the foam roller is also better at hiding any surface blemishes. Make sure you do not get a paint build-up in the rebated holes for the tweeters otherwise they will not fit properly. Final assembly When your boxes have been painted, veneered or whatever, the end of the process involves assembling the crossover network and drivers into the box. First step – insert the plastic tuning vent into its hole in the baffle. Push it down hard to make sure it is flush with the baffle. ‑Next, mount the crossover network inside the panel, adjacent to the hole for the speaker terminals. You will need to drill a hole for a selftapping screw, to secure it through one Here’s one of the two crossovers. It is supplied as you see it here – fully assembled. All you need do is connect the three sets of flying leads to the input terminals, woofer and tweeter (watch the switch of polarity on the tweeters!) and mount the board to the inside back of the enclosure. siliconchip.com.au WHERE can you buy SILICON CHIP Fig.2: the speakers have a very smooth frequency response (from 50Hz to 20kHz,) as shown in this graph. You can get your copy of SILICON CHIP every month from your newsagent: in most it’s on sale on the last Wednesday of the month prior to cover date. You can ask your newsagent to reserve your copy for you. If they do not have SILICON CHIP or it has run out, ask them to contact Network Distribution Company in your state. SILICON CHIP is also on sale in all of the holes in the crossover PC board. (With 20/20 hindsight, we would have drilled these holes before assembling the boxes!). Next, pass the input wires through the back panel hole and push the connectors onto the spade lugs of the terminal panel. Note that they polarised – push the red connector on to the lug for the red (positive) screw terminal and the blue connector to the black (negative) screw terminal. Then pass the tweeter wires through the tweeter hole in the baffle and attach them to the tweeter terminals. Note that this time the connectors are not coloured but the wire with the black strip must go the tweeter’s negative spade lug. Once the wires are on, carefully place the tweeter into its hole and make sure it sits flush with the front surface of the baffle. Carefully secure it in place with five screws – do not over-tighten. Then place the piece of BAF (bond- ed acetate fibre) wadding into the enclosure via the woofer mounting hole. Then connect the remaining crossover wires to the woofer. The connectors for these are different sizes to match the spade lugs on the woofer, so you cannot make a mistake. Finally, secure the woofer with six self-tapping screws. Do not overtighten. Connect to your amplifier, select an input source, sit back . . . and relax! stores . . . again, you can ask the store manager to reserve a copy for you. Or, to be sure that you never miss an issue and save money into the bargain, why not take out a subscription? The annual cost is just $89.50 within Australia or $96 (by airmail) to New Zealand. Subscribers also get further discounts on books, and other products we sell. * Designer, Theloudspeakerkit Availability The kit of two M6 speakers, as described in this article, is available for $599.00 plus shipping. For further information, contact: The Loud Speaker Kit 21 Harrogate St, Leederville WA 6007 Tel: (08) 9382 8588 Fax: (08) 9382 8087 Website: www.theloudspeakerkit.com Fig.3: the impedance is a nominal 8W. Note the double hump below 100Hz which is typical of bass reflex systems. OVERLEAF: Putting the speakers together, step-by-step siliconchip.com.au November 2006  37 Putting them together . . . step-by-step ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; 1 2 Before you start (especially on carpet!) , lay out a sheet of plastic . . . 7 Now it’s time to run a bead of glue around the front panel rebate . . . 13 Clamp the box up firmly and allow it to dry. If you have glue runs, 19 You may need to squeeze them on with pliers. Note the polarity! 38  Silicon Chip 3 . . . and do a “dry run” so you can work out how the pieces fit together. 8 It saves any mistakes later on! If you’re satisfied, pull it all apart . . . 9 . . . and the back panel. Once again, too much glue is better than too little. 14 Push the front panel into position on the box, 15 simply wipe them off with a just-damp cloth. Leave until the glue dries. 20 Screw the input terminals to the back of the case with the screws provided. (Optional): we rounded the box edges with a router make it less “boxy”, 21 Then turn the box over and push-fit the port into its hole. siliconchip.com.au ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; 4 . . . and start running glue along the bottom rebates. Don’t be measly! 10 5 Push both side panels into the bottom rebates. They should be a snug fit. 11 followed by the rear panel. Make sure the edges are all flush. 16 22 Pull the “tweeter” wires through and connect them in the right polarity. Last of all is the top panel. Run the glue in the rebates . . . 17 then sanded and painted the boxes an off-white colour to match our decor. siliconchip.com.au 6 The crossover has to be screwed to the inside of the back panel. 23 7 If necessary, give them a push down or even a gentle tap with a mallet. 12 13 . . . an place the top in position. Push it down (or tap it down) into place. 18 19 Poke the input wires through the hole and attach them to the terminals. Place the tweeter in its hole and align its holes with those in the box. 24 25 Fasten the tweeter to the front panel with the screws provided. Don’t slip! November 2006  39 ; ; ; ; ; ; ; STOP 25 The acoustic wadding is placed inside the box through the woofer hole. 28 Drop the woofer back into its hole and align its screw holes. 28 27 26 As you did for the tweeter, pull the woofer wires through the hole . . . 29 . . . and connect them to the woofer, again taking note of polarity. 30 Screw the woofer into place with the screws provided. Repeat for the other box, connect them to your amplifier . . . and enjoy! Radio, Television & Hobbies: the COMPLETE archive on DVD YES! NA MORE THA URY T N E C QUARTER ICS N O R T OF ELEC HISTORY! This remarkable collection of PDFs covers every issue of R & H, as it was known from the beginning (April 1939 – price sixpence!) right through to the final edition of R, TV & H in March 1965, before it disappeared forever with the change of name to EA. For the first time ever, complete and in one handy DVD, every article and every issue is covered. If you’re an old timer (or even young timer!) into vintage radio, it doesn’t get much more vintage than this. If you’re a student of history, this archive gives an extraordinary insight into the amazing breakthroughs made in radio and electronics technology following the war years. And speaking of the war years, R & H had some of the best propaganda imaginable! Even if you’re just an electronics dabbler, there’s something here to interest you. • Every issue individually archived, by month and year • Complete with index for each year • A must-have for everyone interested in electronics Please note: this archive is in PDF format on DVD for PC. Your computer will need a DVD-ROM or DVD-recorder (not a CD!), Windows 98 or higher and Acrobat Reader V6 or later (free download) to enable you to view this archive. This DVD is NOT playable through a standard A/V-type DVD player. Exclusive to SILICON CHIP ONLY 62 $ + $ 00 7 P&P HERE’S HOW TO ORDER YOUR COPY: BY PHONE:* (02) 9939 3295 9-4 Mon-Fri * Please have your credit card handy! 40  Silicon Chip BY FAX:# (02) 9939 2648 24 Hours 7 Days <at> BY EMAIL:# silchip<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# PO Box 139, Collaroy NSW 2097 # Don’t forget to include your name, address, phone no and credit card details. BY INTERNET:^ siliconchip.com.au 24 Hours 7 Days ^ You will be prompted for required information siliconchip.com.au Star of wonder, star of night! Star of royal beauty bright; westward leading, still proceeding, guide us to thy Perfect Light. Programmable Christmas Star Features H Light enough to hang on the Christmas tree or in a window H Cycles through hundreds of pre-programmed patterns H User programmable (with optional PIC programmer) H Programmable display rate H Patterns can be looped H Twinkle effects H Battery powered H Turns itself off after 3 hours by David H Low component count siliconchip.com.au Meiklejohn November 2006  41 I n November 1998, SILICON CHIP published a very popular Christmas Star project, based on an Atmel microcontroller. Recent advances in microcontroller technology mean that this new design, based on a single 8-pin PIC micro, has considerably fewer components and can run from a pair of 1.5V batteries. As it is also easier to build and you can re-program it if you want different patterns, we believe this new Christmas Star will be even more popular than the original! It runs through a programmed pattern sequence, held in EEPROM on the PIC. With a suitable PIC programmer, such as Microchip’s low-cost PICkit 2, it is possible to load a new sequence into the EEPROM without affecting the underlying code. There’s no need to understand PIC programming to create your own display sequence! How it works Fig. 1 shows the complete circuit, such as it is! It consists of little more than the pre-programmed PIC12F683I/P microcontroller, 20 LEDs and a few resistors. Typically, to control a large number of LEDs using a small number of output lines, the LEDs are arranged in a matrix, say 5x4 for 20 LEDs, with transistors driving each row and/or column. That was the approach taken for the previous Christmas Star project, but not this time! So how do we drive 20 LEDs with an 8-pin PIC and five resistors? Here’s the Christmas Star, actual size, from the front. Each “arm” has the same colour run of LEDs – blue, green, yellow and red, with single white LEDs between.This shot was taken with the LEDs flashing, hence some colour shown. It’s not quite as dramatic as the photo earlier, taken in near darkness! It’s made possible through a technique known as “Complementary LED Drive”. It relies on two factors: 1: LEDs will only conduct (and therefore produce light) when a highenough forward voltage is applied. If the voltage is too low, or reversed, they simply won’t light up. 2: The PIC12F683 has Tri-state outputs. That is, they can be set high (nearly 3V in this circuit), low (close to 0V), or placed into a highimpedance input state, effectively disconnecting them from the circuit (“off”). Further, the outputs can either source or sink current, up to 25mA. As an example, consider what happens when the PIC is configured with pin GP5 high, pin GP0 low, and pins GP1, GP2 and GP4 Tri-stated (disconnected). Current will flow from GP5 47Ω K LED5 A 1 Vdd 10k 3V BATTERY 100nF LED1 GP5 4 IC1 GP4 PIC12F683 MC GP2 GP1 S1 GP0 Vss 8 SC 2006 2 3 5 6 7 47Ω A A K LED6 A LED9 K LED11 K A K LED7 A LED10 K LED12 λ K A A K LED8 LED4 47Ω K λ A λ A K λ LED15 A λ λ LED16 K K LED18 K A λ A LED17 A LED20 K λ λ K λ λ K A λ K K LED14 λ λ A λ LED19 A K λ λ LED3 47Ω λ K LED2 47Ω LED13 A λ λ A A PROGRAMMABLE CHRISTMAS STAR K ALL LEDS A Because the PIC chip takes care of timing, sequencing and lighting the LEDs, the circuit is extremely simple. You don’t have to follow the LED colours used in the prototype but the patterns will obviously be different. 42  Silicon Chip siliconchip.com.au LED18 LED20 LED1 LED5 LED19 LED14 + BATTERY – 100nF LED17 47Ω 47Ω 10k IC1 PIC12 F683 S1 LED11 LED4 47Ω 47Ω 47Ω LED2 LED6 sa 3. mts 1 ir V h LED15 C LED13 ra tS LED16 LED3 LED7 LED12 LED9 LED10 LED8 About the only thing that you can do wrong when assembling the Christmas Star is to put a LED (or the PIC chip) in the wrong way, or to have a bad solder joint underneath. Otherwise it should be pretty much plain sailing, even for a complete novice! GP3 high until S1 is pressed, pulling the input low. The software polls for this at the end of each display cycle and if S1 is pressed, it puts the PIC into a low-power sleep mode. The PIC is then set to automatically wake up if the switch is pressed again. Debouncing is done in software, so there is no need for external debounce circuitry. Power is supplied direct from two 1.5V batteries. N cells were chosen because their size makes them easy to mount unobtrusively on the back of the board. But cheaper AAA cells will also fit, albeit a little less neatly. They’ll also last longer. Alkaline batteries will provide more than 50 hours continuous operation, and should last up to two years with the circuit in sleep mode (“off”). Finally, a 100nF bypass capacitor is used to smooth the power supply to the microcontroller. It helps to keep the PIC stable, particularly as the batteries discharge toward the PIC’s minimum operating supply voltage of around 2V. Construction through resistor R1, then LED19, returning through R5 to GP0. So LED19 will light up. Since LEDs are one-way devices, current can’t flow through LED20, so it stays off. But there are other paths for current to flow from GP5 to GP0. For example, via LEDs 9 and 10 in series. But these two LEDs in series are in parallel with LED19, which is conducting. Here’s where factor 1 (which we mentioned earlier) comes into play. The forward voltage across a conducting LED is roughly constant; for a red LED it is around 2V. The voltage drop across the series combination of LED9 and LED10 must be the same as that across LED19. So each of LED9 and LED10 will have a forward voltage of only a half that of LED19. If LED19 is turned on with a 2V drop, there will be a drop of only 1V across each of L9 and L10 – not enough to make them conduct. So they won’t light up. You’ll find many other possible paths for forward conduction; a particularly obvious one is the series combination of LED1, LED2, LED3 and LED4. Similar reasoning shows that the voltage across each is only a quarter that across the conducting LED19; not enough for them to turn siliconchip.com.au on. Similarly for other paths, such as the non-obvious LED13, LED16, LED17 combination. In fact, with GP5 high, GP0 low, and the other outputs disconnected, only LED19 will have enough forward voltage to light up. Using this technique, it is possible for five outputs to uniquely address up to twenty LEDs, with the limitation that only one can be turned on at once. To overcome this limitation, the software uses multiplexing to make it appear as though more than one LED is lit at the same time. The software displays patterns on up to four LEDs which are turned on in sequence, each for 200µs, at nearly 1250Hz, creating the illusion that the four LEDs are on at once. The remainder of the circuit is very straightforward. Resistors R1-R5 limit current to the LEDs. The current path to a given LED will always flow through two of these resistors, so the effective resistance in series with each LED is 94W. Assuming a 3V power supply, and a red LED with a forward voltage drop of 2V, LED current will be 10mA, well within the supply capability of the PIC. Switch S1 is used as an on/off switch. Resistor R6 holds the PIC pin The Christmas Star is built on a single-sided PC board, cut in the shape of an eight-pointed star. All components are mounted on this PC board, so construction is very straightforward. Firstly, if you’re not building from a kit, you’ll need to choose your LEDs. In the prototype, all the LEDs are clear, high-intensity types. Five colours were used: red, green, yellow, blue and white, arranged with four red LEDs forming an inner ring, then yellow, green and finally blue at the outermost of the big points and white LEDs used on the four small points. Of course, you can arrange the colours any way you want; after all, it’s your star! And the choice of high intensity or diffused types with a wider viewing angle is entirely up to you. About now, you may be wondering how it is possible to use blue, or indeed most high-intensity types, when they have a forward voltage higher than the supply voltage of 3V. In practice, they do run at voltages down to 2.5V or so; they’re just not as bright as they would otherwise be. At low voltages, they’re still about as bright as a “normal” LED; quite bright enough to light up nicely at night time! November 2006  43 Parts List – Programmable Christmas Star 1 pre-programmed PIC12F683I/P IC 20 5mm LEDs (see text for colours and types) 1 100nF monolithic capacitor 1 10kW 1/4W resistor 5 47W 1/4W resistors 1 6mm PCB tactile switch 1 N-cell battery holder with fly leads (or AAA – see text) 2 N-cell alkaline batteries (or AAA) Double-sided foam tape (to mount battery holder) These two shots show how the dual “N” cell battery holder fits on the back of the PC board, secured in place with double-sided foam adhesive tape or pads. Note that a “AAA” holder will also (just!) fit on the PC board and will give longer battery life than the “N” cells used in the prototype. Even so, you should expect about 50 hours of display from the pair of “N” Cells. By the way, don’t mistake the 1.5V “N” cells for 12V remote control batteries. They are not too dissimlar in size and 24V would create a whole different (brief!) display . . . An IC socket for the PIC is strongly recommended. Besides reducing the risk of damaging the chip, it means that later, if you acquire a PIC programmer, you have the possibility of creating your own display pattern. Begin by soldering in the resistors, then use one of the discarded resistor leads for the single wire link. Next comes the IC socket, the capacitor, the pushbutton switch and the LEDs. Take special care of the correct orientation of each LED. If you put any in backwards, the star will still operate, but the patterns will be wrong. Orientation is shown on the PC board silk-screen overlay. 44  Silicon Chip At this point you can test the circuit, with the IC socket empty, by putting the two batteries into the (not yet installed) battery holder, then putting the battery holder leads (ie 3V) across various combinations of pins 2, 3, 5, 6 and 7 on the IC socket. For each different combination, a single LED, specific to that combination, should light strongly. Note that it is possible, if you have used a range of LED colours, that you will see other LEDs light very dimly in addition to the single strong light. If so, don’t worry, you won’t notice that effect when the display is operating. If no combinations produce any light, use a multimeter to check that you’re getting 3V from the battery pack. If you see more than one LED light up strongly at once, you probably have one of them in backwards, or perhaps a solder bridge on the board. If one combination doesn’t produce any light, while others do, you probably have either a dead resistor or LED, or a soldering problem such as a dry joint. If all the LEDs check out OK, remove the batteries from the battery pack, cut the leads suitably short (15mm or so), thread them from the back of the board to the front through the hole above C1. Solder the wires back through the board in the normal way to the pads marked + and –, being careful of polarity! If you now reinsert the batteries, nothing should light up; if it does, you have a short somewhere. Next remove the batteries again and use double-sided foam tape to stick the battery holder to the bottom of the board (see photos at left). Finally, you’re ready to insert the microcontroller. Taking antistatic precautions (touch an earthed case first!), carefully insert the PIC into the IC socket, with the notch on the IC toward the capacitor. Make sure that none of the PIC leads are bent or skewed in the process. Now insert the batteries again and you’re finished! At this point, the Capacitor Codes Value (mF value)   IEC    EIA     Code    Code 100nF 0.1mF 100n 104 siliconchip.com.au The wires from the battery holder come up through the board from underneath, then solder back through the board in the normal way. This helps take the strain off the cables and pads. Where from, how much: Pre-programmed PIC 12F683:......... $12 Pre-programmed PIC + PC board:... $17 Complete kit of parts (including clear LEDs, excluding batteries):..... $39 All plus $5 post and packaging within Australia Contact details for ordering kits are: Via website: www.gooligum.com.au Or email: david<at>gooligum.com.au display may start by itself but more normally, the star will do nothing until you momentarily press the button. The display sequence should now start. Operation Very simple – push the button to start, and press it again to stop. But if you forget and leave the display running, the star will shut itself off after around 3 hours. If this happens, just press the button again to restart. Creating your own patterns Although the PIC source code has not been (and will not be) released by the author, the command codes which define the display patterns are held in unprotected EEPROM, which you can update, independently of the protected code held in flash memory, with a suitable programmer. You’ll find the information you need to reprogram overleaf. PIC programmer An excellent low-cost programmer is Microchip’s PICkit2, available from Farnell for around $65, or as part of a starter kit for $92. It comes with software that allows the PIC’s EEPROM to be updated without affecting the program code in flash memory. The new command codes can be typed directly into the PICkit2 EEPROM window and loaded to the microcontroller. But it’s very important to uncheck “Program memory”, so that the program code itself is not overwritten. See the screenshot at right. If you don’t uncheck this box (ringed in red above) when reprogramming your Christmas Star, you will overwrite the program itself, rendering the star useless! Resistor Colour Codes No. o 1 o 1 Value 10kW 47W siliconchip.com.au 4-Band Code (1%) brown black orange brown yellow violet black brown 5-Band Code (1%) brown black black red brown yellow violet black gold brown OVERLEAF: Pattern Sequence Command Codes and Pattern Definitions for those who want to re-program the patterns. November 2006  45  Pattern sequence command codes Code Command 0 Pause 1 - 91 Pattern Description All LEDs off. Use for a short pause between pattern sequences Display a pre-defined pattern of up to four LEDs which are on “at once”. For a list of and details of each pattern, refer to the next page. LEDs are lit, one at a time, in pseudo-random order, in quick succession to create an overall “twinkling” effect. 92 - 126 Twinkle Twinkle rate = (code-91)ms between changes. If the code value = 92, a different LED is lit every 1ms – you may think too fast for the eye to see. But due to imperfections in the “random” number generation, you’ll still see a shimmer at this maximum twinkle rate. 127 End of sequence 128 End loop For code = 126, the twinkling is at its slowest, around 29Hz. Marks the end of the programmed sequence. Not necessary if your display codes fill the whole EEPROM, as the interpreter will restart at the beginning if the end of the EEPROM is reached. Go back to first pattern in current loop – see below. Use this to create loops, to avoid having to fill the EEPROM with repeated sequences of codes to create a repeating effect. Instead, place a “start loop” instruction at the start of the sequence, and an “end loop” (128) instruction at the end. 129 - 191 Start loop Repeat count = code-128 EG. to repeat a sequence of patterns four times, you would place a code of 132 (= 128 + 4) before the first pattern code, and a code of 128 after the last. Note that nested loops are not supported. An “end loop” code will always return to the most recent “start loop”. Sets the display rate, i.e. the time spent displaying each pattern before moving to the next in sequence. It allows you to vary the speed of the display in different parts of the presentation. 192 - 255 Set Speed Freq = 1000000/[8192(256-pattern)] Hz The default display rate, if you don’t set your own speed, is 6.8Hz Max. freq. (code = 255) is 122Hz. Min. freq (code = 192) is 1.9Hz. As an example of how to put it all together, here’s some code to twinkle at a moderate rate for 10s, then turn off (pause) for 1s, then repeat: Code Comment 195 display speed = 2.0Hz 148 repeat following patterns 20 times (128+20=148) 101 twinkle at 101-91=10ms per change (100Hz) 128 end loop 0 pause (all off) 0 pause again – at 2Hz we need 2 pauses to make 1 second 127 end sequence (repeat from beginning) 46  Silicon Chip siliconchip.com.au Christmas Star Pattern Definitions Code Description LED 1 LED 2 LED 3 0 All off LED 4 Individual LEDs 1 1 only 1 2 2 only 2 3 3 only 3 4 4 only 4 5 5 only 5 6 6 only 6 7 7 only 7 8 8 only 8 9 9 only 9 10 10 only 10 11 11 only 11 12 12 only 12 13 13 only 13 14 14 only 14 15 15 only 15 16 16 only 16 17 17 only 17 18 18 only 18 19 19 only 19 20 20 only 20 Alternate LEDS - 4 per diagonal 60 SE 1 3 NW 1 3 3 10 15 5 61 SE 2 4 NW 2 4 7 8 16 18 62 NE 1 3 SW 1 3 14 19 2 11 63 NE 2 4 SW 2 4 13 20 6 9 64 SE 1 3 NW 2 4 3 10 16 18 65 SE 2 4 NW 1 3 7 8 15 5 66 NE 1 3 SW 2 4 14 19 6 9 67 NE 2 4 SW 1 3 13 20 2 11 Inner and outer - 2 per arm 68 SE arm 3 8 69 NE arm 14 20 70 NW arm 15 18 71 SW arm 2 9 Arms 21 SE arm 8 10 22 NE arm 14 13 23 NW arm 15 16 24 SW arm 2 6 7 19 5 11 3 20 18 9 Rings 25 ring 1 - inner 3 14 26 ring 2 - inner mid 7 13 27 ring 3 - outer mid 10 19 28 ring 4 - outer 8 20 29 Small points 12 4 15 16 5 18 1 2 6 11 9 17 Complimentary pairs 30 NS 1 12 31 EW 4 17 32 SE1 NW1 3 15 33 SE2 NW2 7 16 34 SE3 NW3 10 5 35 SE4 NW4 8 18 36 SW1 NE1 2 14 37 SW2 NE2 6 13 38 SW3 NE3 11 19 39 SW4 NE4 9 20 Inner and outer - 4 per diagonal 72 SE NW 3 8 15 18 73 NE SW 14 20 2 9 Middle LEDS - 2 per arm 74 SE arm 7 10 75 NE arm 13 19 76 NW arm 16 5 77 SW arm 6 11 Middle LEDS - 4 per diagonal 78 SE NW 7 10 16 5 79 NE SW 13 19 6 11 Inner and outer half arms - opposites on diagonal 80 SE inner NW outer 3 7 5 81 SE outer NW inner 10 8 15 82 NE inner SW outer 14 13 11 83 NE outer SW inner 19 20 2 18 16 9 6 Inner and outer half arms - perpendicular opposites 84 85 86 87 88 89 90 91 Half arms 40 SE inner 3 7 41 SE outer 10 8 42 NE inner 14 13 43 NE outer 19 20 44 NW inner 15 16 45 NW outer 5 18 46 SW inner 2 6 47 SW outer 11 9 Complimentary halves 48 SE NW inner 3 7 15 49 SE NW outer 10 8 5 50 SW NE inner 2 6 14 51 SW NE outer 11 9 19 Alternate LEDs - 2 per arm 52 SE 1 3 3 10 53 SE 2 4 7 8 54 NE 1 3 14 19 55 NE 2 4 13 20 56 NW 1 3 15 5 57 NW 2 4 16 18 58 SW 1 3 2 11 59 SW 2 4 6 9 16 18 13 20 SE inner NE outer SE inner SW outer NE inner SE outer NE inner NW outer NW inner NE outer NW inner SW outer SW inner SE outer SW inner NW outer 3 3 14 14 15 15 2 2 7 7 13 13 16 16 6 6 19 11 10 5 19 11 10 5 20 9 8 18 20 9 8 18 Commands 92-126 Twinkle Rate: (code-91)ms between changes 127 End of sequence 128 End of loop Go back to first pattern in current loop 129-191 Start loop Start of loop: repeat count = code-128 times 192-255 Set Speed Freq = 1000000/[8192(256-code)] Hz SC siliconchip.com.au November 2006  47 SERVICEMAN'S LOG So hopelessly devoted to you It’s amazing how some people become attached to a particular piece of equipment that they’ve owned for some years. If it breaks down, then it just has to be fixed but who am I to complain? Mr Lengel brought in his 1999 JVC AV-P29WH (CD chassis), whinging in his thick East-European accent that his beloved set had died – and it was only seven years old! From the way he carried on, you’d think there had been a death in the family. You’ve “gotta” love blokes like this! Anyway, his set wasn’t completely dead – it did try to switch on. You couldn’t hear any sound but there was a rush of EHT static and the red and green LEDs were flashing on the front of the set. Well, at least the +5V rail was OK. The service manual states that there should be 1200V peak-to-peak on the collector of the horizontal output transistor (Q522, 2SD2553-LB) but the oscilloscope showed there was only 800V. What’s more, this transistor was getting hot and there was a smell of burning. There was no sign of ringing on the line pulse and the +15V and +25V rails were OK. However, the screen voltage was down from 200V Items Covered This Month • JVC AV-P29WH TV set (CD chassis) • Sharp CX-68K5X TV set (NFC chassis) • Yamaha RX-V750 (A) AV Receiver • • • Teac CT-F683 TV set Teac CT-M342HW TV set Panasonic PanaSync S110i (TX-DIF64MA 21HV125) computer monitor 48  Silicon Chip to just 80V and I suspected that there was something wrong with the flyback transformer. Unfortunately, I was wrong, as replacing the flyback transformer (a $150 part) made no absolutely difference. Next, I decided to check the protection circuits and started with Q591, only to find this was an “optional” (OPT) transistor on the circuit diagram. Oh, goodie, we were making progress! I continued following the x-ray protection circuit and checked Q571, Q451, Q452 and Q981 all the way to pin 18 of microprocessor IC701. It was then that I struck a clue. A few voltage checks in this part of the circuit revealed that the +12V rail was very low, at about 1.2V. I followed this back to IC971, a BA12T 12V IC regulator which was getting very hot. This device is a low-impedance highcurrent device and so had to be ordered in specially. Anyway, much to my relief that fixed the problem and Mr Lengel had his beloved set back again (after whinging about the service cost of course)! Shrinking picture I was called out to repair a 2000 Sharp CX-68K5X (NFC chassis) which, according to the client, had a shrinking picture. When I looked at the picture, it was dull, dark and was suffering from horizontal fold over. The line output transistor (Q1830, 2SD2581) was getting hot as well. From experience, I suspected the deflection yoke and so I loosened it and removed it from the CRT (A68KTB357X034). This clearly showed that the horizontal windings had been cooked and had melted the lightgrey former. I went back to the workshop and made a few phone calls. First, I tried to find someone who might have scrapped one of these sets so that I could buy a secondhand yoke. When that failed, I inquired about the availability of a new one. Apparently they are available and after quoting for the job the client agreed for me to go ahead. In due course, the new yoke arrived but when I unpacked it, I immediately noticed that it was black in colour and shaped differently to the original. However, I put that down to an updated design and went ahead with the installation. Unfortunately, the picture was only slightly better. The horizontal foldover was gone but the lack of width remained, though the east-west pincushion and trapezoid were OK. Anyway, I decided to check these circuits out. First, I noticed that R1675 6.8W 3W was getting very hot and had partially melted the polyester capacitor next to it (C1670, 4.7mF 100V). I checked the values of these components but they were still spot on. I also checked Q1671 (2SD1830), L1670 (0.36mH) and diodes D1610, D1632 and D1633 and these were also OK. Reluctantly, I came to the conclusion that I had been sent the wrong deflection yoke – particularly as the new one had additional coils fitted. As a result, I checked with my supplier and confirmed that RC1LH1879CEZZ was the correct part number. I then left a message outlining the problem with the Technical Support Officer for Sharp Corporation and he responded with a message for me to read Service Bulletin CTV182. This bulletin told me that there are two types of CRT fitted to this set, the other being the VB68QBC230X3E. The yoke I had been supplied with was for this CRT only and, what’s more, the other one is no longer available. siliconchip.com.au And so all my hard work had been for nothing! The set has now been written off now as a new CRT is currently over $1100 trade. Fortunately, I did get a refund on the new deflection yoke. A dead Yamaha A dead 2004 Yamaha AV Receiver and 5 x 100W Surround Amplifier (RX-V750 [A]) was recently brought into the workshop. This is a pretty expensive top-line home-theatre amplifier and uses some up-to-the-minute technology. The reason it was dead was because the relay which switches the AC line to the main power transformer wasn’t latching. There was, however, +12V and + 5V (derived from the subsupply) from IC501 to microprocessor IC502 (CPU MC30622MHP-161FP) but no output from pin 69 (PRY) to the relay (RY401). I was subsequently advised that the microprocessor can give trouble in this unit, which filled me with dread as it is an expensive 100-pin surface-mounted chip. However, as luck would have it, an identical unit came in with a straightforward fuse problem. Having a twin meant that I could swap boards and I was able to replace the FUNCTION (2) board which carries the microprocessor. This made no difference, which saved everyone a small fortune. I then went on to examine the RESET line in pin 12. I noticed that there appeared to be a hum on this line and it was unstable and down to 2.5V instead of 5V. I followed this line to the SUB TRANS board and began noticing quite a lot of inconsistencies between this unit and the good amplifier, particularly with regard to irregular waveforms. The SUB TRANS power board is relatively small but still has quite a few components on it. Swapping this board with the good amplifier quickly confirmed that it was indeed the cause of the problem, so I immediately set about testing and replacing some of the more critical parts. I got nowhere until I came to FET Q404 (2SK3850). Although this measured differently from its twin, it didn’t actually measure completely faulty. However, after swapping it, I at last got the amplifier to power up on its own, so it must have been crook. Unfortunately though, that wasn’t the end of the matter. Much to my frustration, the amplifier was still closing down intermittently and the RESET line and other waveforms were still incorrect. I subsequently swapped quite a few more parts over without result before turning in desperation to someone who was an expert on this series of amplifiers. Apparently this board has been known to occasionally give strife and the fault is thought to be caused by a diode intermittently breaking down. As the module is only $35 retail, it’s simply easier (and more cost effective) Home to over 180,000 products Where all the leading brands live GO TO siliconchip.com.au www.rsaustralia.com RS213SC International Rectifier 100%C, 50%M. Panasonic 4col. Reliable • Simple November 2006  49 Serviceman’s Log – continued However, I also replaced C910 & C908 for good measure. Unfortunately, there’s nothing I can do for the customer’s wife and dog. Hospital TVs to replace it, so that’s what I ended up doing. The new module has also apparently been improved and carries several minor modifications. Anyway, it did the trick. It comes in threes I was asked to do a service call on a Teac CT-F683 TV set that was dead. When I arrived and knocked on the door, I was greeted by a man with a very sad expression. And was he having a run of bad luck. “Two weeks ago, my wife died. Last week, my dog died and now my <at>#$%& TV is dead”, he told me. I immediately mouthed off some suitable platitudes and refrained from making my standard “bad luck runs in threes” quip. This 68cm silver TV looks more modern than it actually is. In fact, the circuitry is quite conventional and has been around for a long time. Fortunately, the power supply is on a sub-board at the rear of the set and Teac in their wisdom have used an inordinate number of screws to hold it down. Once you have spent the appropriate time removing these screws, the access isn’t too bad, as the leads are quite long. It also helps to remove the AV panel at the rear. My initial checks showed that 240V AC was arriving at the board, which meant that the switch and fuses were OK. Other than that, there was no 50  Silicon Chip activity at all and the relay (RLY902) wasn’t latching. There were no dry joints and nothing was burnt out that I could see. However, having serviced a couple of these sets before, I went straight for two resistors – R970 & R971 (15kW 2W) – which are in the lefthand corner and which looked discoloured. These supply the voltage directly to the relay coil. They measured OK but I replaced them anyway, to ensure long-term reliability. The relay circuit is slightly unusual as it is not there to switch the set on and off. Instead, it acts as a safety cutout if too much current is drawn by the low-voltage power supply involving transformer T970 and diode D976. This current is monitored by IC970 (TEA1501), which then controls Q971 and Q970. Earlier Teacs used a very similar power supply, without this safety circuit and it was very reliable. In fact, it is ironic that it is the additional safety circuit that now gives all the trouble. Resisting the temptation to just disable it, I decided to replace the four small electrolytics on the board – ie, C971, C972, C975 & C976. And when I removed C976 (1mF 250V), it was obvious that this was the culprit as it was leaking fluid down one leg. C972 (4.7mF 160V) wasn’t much better. That was enough to repair this circuit and the set now came on perfectly. I am occasionally called out to repair TV sets for a local hospital. These are modified Teac CT-M342HW sets and almost all of their problems can be sheeted back to capacitors C908 (47mF 63V) and C909 (10mF 100V) which are located next to heatsinks and, as a result, dry out rapidly with the heat. This problem, combined with power surges in the hospital, causes havoc with the rest of the set. Fortunately, the faults are on the whole straightforward and are caused by excessive voltage being applied to sensitive circuits. I do have three odd faults with these sets though. One is intermittent weird patterning and streaking of the picture. This is due to the difficulty of trying to put the back on and lining up the chassis with the rails on the back shell of the cabinet. These rails tend to hit two 0.22mF capacitors (C303 and C304) on the edge of the board next to the tuner, making them dry jointed. These two capacitors are part of the 0-33V tuning voltage circuit for the tuner. Re-siting and resoldering them fixes this problem. The second problem I have had was switching the set on and off using the microprocessor. The power standby is controlled from pin 7 and this signal goes to Q601, Q905, Q906 and, finally, Q907 which switches the main +110V. During the normal course of repairs, Q907 (2SC2335) can go short-circuit and sometimes takes out Q906 (2SA1013). However, there is a 100kW resistor (R921) between Q907’s base and the collector of Q905 and two series reversed diodes (D913 & D914, S5295C) Q907’s emitter to the base of Q905. As a result, I have never had Q905 (2SC2230A) actually fail on me. However, I have had many cases where it refuses to switch on with 0.6V between its base and emitter. In the end, I found that the only permanent solution is to replace it with a 2SC2335. Lastly, I had one interesting fault with one set, where the complaint was lack of height. This problem could be overcome by going into the service menu on the RC-747 remote control (there are two little holes on top of the siliconchip.com.au LTW Harsh Environment Connectors www.ltw-tech.com C-16 Line Multipin Circular Line D-Sub Multipin Multipin Circular C-16 Style RJ45 Miniature DIN Available in Australia from Altronic Distributors Agricultural • Industrial • Mining • Marine remote to access the menu) and adjusting it (normally, HIT is set for approximately 14-17). However, this wasn’t really the correct solution and after poring over the vertical timebase, checking this and replacing that, I came to the conclusion that it was due to the 110V B+ rail being too high (it actually measured 130V). I adjusted VR901 and noticed the B+ rail swing down from 130V to 90V with only a very small movement of the wiper. As there was some of that dreadful “snot” glue on it, I replaced the pot but it was still far too sensitive – in fact, it was impossible to set the voltage on exactly +110V. No matter how hard I tried, it was always too high or too low, with the picture height varying accordingly. Well, I must admit that this had me perplexed. I spent a lot of time checking out the control circuitry, especially the three reference zener diodes. Enlightenment only came when I measured the B+ to be much higher and varying on the cathode of diode D911 following the chopper transformer. The cause was of this was a leaky 100mF 160V electrolytic capacitor (C917) at the junction of D911’s cathode and Q907’s collector and replacing it solved all the problems. Don’t forget the CRT With people so keen to purchase the new LCD monitors, it’s easy to forget that the old CRT monitor is still an excellent alternative – the more so because competition has forced their prices down to unbelievable levels. I had two beautiful 21-inch 2000 Panasonic PanaSync S110i computer monitors (TX-DIF64MA 21HV125) come in which were either intermittently turning off or sometimes failing to start. They had been bought secondhand for a song (about one tenth of their value) only two years ago and had performed flawlessly. Now that they were faulty, and because we were starting from such a low value, the repair had to be equally cheap or it was computer heaven for these two. At switch on, both were trying to come on but were then closing down due to some sort of protection circuit. siliconchip.com.au LTW connectors represent the ultimate in value and reliability for manufacturers of industrial equipment requiring waterproof connectivity. Available in IP66, 67 & 68 ratings for use in almost any environment. Altronic Distributors carry a range of products ex stock (see website for range available). Other LTW models available upon request. Minimum quantities apply. Sydney Melbourne Perth DISTRIBUTORS PTY. LTD. Phone: 1300 780 999 Web: www.altronics.com.au On one, if I continually switched it off and on, you could eventually just see a white line across the screen. And that was the clue I was looking for. Panasonic, being a premium brand, generally make an excellent product but even so, if the problem couldn’t be fixed within an hour, it was going to be curtains. Well, most of that time was spent removing and replacing the chassis from its impregnable metal cage. I removed a bucket or two of screws before the chassis was even half accessible. And once it was completely out, there was going to be no way to run these sets, so the fault had to either be visible or measurable with an ohmmeter. Fortunately, in both cases, I could see that the vertical output IC (IC491) had a row of very fine dry joints and all I had to do was resolder them. A millennium later I had the sets all back together, ready for the final tests. Both monitors performed faultlessly – if only they were all that easy. Grundig install Recently, I was asked to do an installation and checkup on a complete Grundig system comprising a TV set, video, DVD, and digital set top box (DSTB) When I arrived, the first thing I noticed was that it had already been installed by a dealer using phono leads and SCART adapters and also that the camera/game input at the front of the TV had been used. However, to get the most out of SCART systems, you need to use a fully-wired 21-pin lead. These aren’t easy to get hold of because the catalogs and November 2006  51 Serviceman’s Log – continued packages never tell you whether they are fully wired. The only way you can tell is to remove the plug covers and check yourself. If they aren’t, finding another supplier is another matter altogether. The next drama was to find out which sockets to plug the leads into. Silicon Chip Binders REAL VALUE AT $13.95 PLUS P & P H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A13.95 plus $A7.00 p&p per order. Available only in Australia. Just fill in the handy order form in this issue; or fax (02) 9939 2648; or ring (02) 9939 3295 & quote your credit card number. 52  Silicon Chip Most of my client’s instruction books were missing and the ones he did have had very little information. However, most of the information is actually in the TV set’s “Easy Dialog” self-help menu system. I connected the DVD output lead into the orange SCART socket (AV2) and the VCR to the black AV1 socket. The DSTB went to the blue AV2 socket (DEC/EXT) on the VCR. All AV connectors were set to RGB. My client had complained of the recording quality on his VCR and I soon discovered this was because he was recording poor-quality analog signals and not the standard definition signals from the DSTB. The reason for this was quite simple – the latter was dead so arrangements had to be made to take it back to the authorised service centre. I then decided to check out the DVD player, using a DVD which I grabbed from a pile next to the TV. This didn’t go smoothly either because, every few seconds, the picture rolled and the colour dropped out. This also happened with the drop-down menus and the DVD screen saver. I eventually discovered that by swapping the VCR and DVD leads at the back of the TV, I could get good pictures on both inputs. This surprised me but apart from the TV OSD menu saying it was on VCR instead of DVD and vice versa, everything else was working properly. I left the client to organise the repair of the DSTB and made arrangements to return when it was done. In the meantime, I contacted several people in the Grundig support system and I also trawled the web to try get to the bottom of this odd rolling on DVD. Noone within the company knew what was causing the problem off-hand but they said they would try to track it down and get back to me. When the DSTB arrived back with a software upgrade, I reconnected it and left, telling the customer that I was still chasing the information on the other problem. However, days turned into weeks and to make matters worse, the VCR was “playing up” again. I called back once more and found that the DSTB had failed again. This time, I suggested that when he took it back, he should also take the DVD player and VCR and have them checked. The service centre repaired the DSTB again but no faults were found with anything else. Eventually Steve from “Electronics Today” came out and solved the problem. There was in fact nothing really wrong – except me. Everything was plugged in correctly but when I had reached over and picked up the first DVD from the client’s collection, I had actually chosen an NTSC 60Hz Region Zone 1 disc! And the reason it played back on the AV1 (VCR) input was because that input was presumably configured for AUTO system while AV2 was configured only for PAL. All that was required was to play a PAL 50Hz Region Zone 4 disc in the DVD player and it would have worked. I haven’t been back since, so I don’t know whether or not Steve reconfigured AV2 for AUTO (assuming it can be reconfigured). So how did Steve know what the problem was? Well, he has been working on Grundigs for a long time and there’s no substitute for experience. Still, I should have twigged – it’s amazing what you overlook sometimes. Finally, there is an extra button on the TV remote Telepilot 110C called the MODE function and we couldn’t work out how this let this remote control work the VCR or the DVD player as well. Steve let us in on the secret. This function only activates the buttons for the other equipment while the LED is on, which is for about 10 seconds. Devilish cunning, those Germans – it makes you wonder how they lost the war! SC siliconchip.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 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. 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 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 t f i G s a m t s i r h A C ne lucky o r o P f I H C N O C I SIL criber... subs YES! Simply take out a new subscription (or renew an existing one) and you’ll go into the Christmas Eve draw for a pair of these M6 bass-reflex kit speakers, as described in this issue of SILICON CHIP, valued at $599. Australian and New Zealand subscribers are eligible to win this superb prize, courtesy of theloudspeakerkit.com Speakers will be supplied in flat (kit) form and raw finish, ready for you to assemble. Only PVA glue and a Phillips screwdriver required. All subscriptions and renewals received from now until 5pm on Friday, December 22 will be included in the computerised draw. DON’T MISS OUT! COMMENCE OR RENEW YOUR SUBSCRIPTION NOW! If your subscription is not due for renewal until after Christmas, you can renew now to enter and the renewal will commence at your due date Phone/Fax order form & Tax Invoice YOUR SUBSCRIPTION ORDER: Silicon Chip Publications Pty Ltd ABN 49 003 205 490 All subscription prices include pack and post. Australian prices include GST. Your name:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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BY FAX:# (02) 9939 2648 24 Hours 7 Days <at> BY EMAIL:# silchip<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# BY INTERNET:^ PO Box 139, siliconchip.com.au Collaroy NSW 2097 24 Hours 7 Days 2006  61 # Don’t forget to include your name, address, phone no and credit card details. ^ You will N beovember prompted for required information 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. Wiegand decoder Many security access control systems incorporate a data protocol called Wiegand. Wiegand was named after its inventor John R. Wiegand and the term, while defining a particular data format, is more commonly used to describe the Wiegand Effect. The Wiegand Effect is exhibited when the internal magnetic fields in specially prepared wires swiftly reverse polarity when exposed to external magnetic fields. This reversing magnetic field can be captured as a negative-going electrical pulse. The Wiegand data protocol incorporates two separate logic lines, a “one” line and a “zero” line. As the Wiegand effect can only produce negative-going electrical pulses, both lines will individually go low to indicate the presence of a bit. Wiegand wire (wire specially developed to exhibit the Wiegand Effect) is very hard to duplicate. This is why the technology is heavily used in security access cards and “pin” cards. This simple decoder circuit can be used to convert dual channel, nega-­ tive-going electrical pulses from a Wiegand magnetic reader head to standard hexadecimal format. The circuit consists of a 74HC00 quad NAND gate and two cascaded 74LS164 8-bit shift registers. Where necessary, the number of shift registers can be increased to suit the bit depth of the Wiegand data stream. For example, we used 26-bit Wiegand for our experiments (two parity bits + three bytes of data) and this required four 74HC164s. The “zero” and “one” lines are fed into IC1a to generate a clock signal for the cascaded shift registers. The second NAND gate (IC1b) is wired as an inverter and drives the data input (pin 1) of the first 74HC164 (IC2). A negative-going pulse on the “one” line will cause a clock pulse and a logic one will be captured. A negative-going pulse on the “zero” line will cause a separate clock pulse and a logic zero will be captured. Once all of the bits have been clocked in, the resultant hex code is available at the register outputs. Ben Gillson, via email. ($40) Issues Getting Dog-Eared? Keep your copies safe with these handy binders. REAL VALUE AT $13.95 PLUS P & P Available Aust, only. Price: $A13.95 plus $7 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or ring (02) 9939 3295 and quote your credit card number. 62  Silicon Chip siliconchip.com.au Electronic combination lock This simple 7-digit combination lock can be hard-wired for any combination that you choose. It’s based on a 4-bit divide-by-8 Johnson counter (IC1), 10 pushbutton switches and an NPN transistor (Q1). At power up, the 47mF capacitor connected to pin 15 of IC1 charges to a logic high level via an 820kW resistor, holding the counter in the reset state. In this condition, output O0 (pin 2) of the counter is high, while all other outputs are low. If switch S2 is now pressed, transistor Q1 conducts, discharging the 47mF capacitor via D1 and the 82W resistor and releasing the counter’s reset input. When S2 is released, Q1 switches off and its collector is pulled high, generating a rising edge on the counter’s CP0 (pin 14) input. A 10mF capacitor and 10kW resistor in the base circuit of Q1 forms a simple filter to prevent switch contact bounce from generating multiple clock pulses on CP0. The clock pulse advances IC1’s count by one, so O0 goes low and O1 goes high. Therefore, switch S7 must be pressed next, as it’s wired to output O1, and the sequence repeats. The time required for the 47mF capacitor to charge to a logic high level is the maximum time that can lapse between switch presses – otherwise, the counter will be reset. When all switches have been pressed in the correct sequence (S2-S7-S3-S4-S5-S2-S2 as shown), output O7 (pin 10) of the counter goes high for about three seconds. This could be used to power a lock or motor circuit via a relay driver. Raj. K. Gorkhali, Kathmandu, Nepal. ($30) With the components values selected for the low-pass filters, mains interference is virtually excluded. VR1 is an offset adjustment and serves to keep the op amp’s output normally high or normally low, as desired. This should be a multi-turn trimpot for precise adjustment. To set up the circuit, connect a 12V battery or regulated 12V DC power supply, then turn VR1 until LED1 just extinguishes. Finally, slip the coil under the track, clip a small neodymium magnet to the underside of the train and you are ready to go. If desired, IC2’s output (pin 6) can directly drive a power MOSFET or it can be used to trigger a 555 timer monostable circuit. Thomas Scarborough, South Africa. ($30) Model train detector This circuit can be used to detect a model train on a track. A flat coil slipped under the track detects the field of a small magnet attached to the underside of the train. With L1 consisting of a minimum of 24 turns of enamelled copper wire (width to suit track), the circuit should be able to detect a neodymium magnet at several centimetres. The coil is wired directly across the inputs of an LM380N audio amplifier, which greatly amplifies the small signal from the coil. This is then fed to “tracking” comparator IC2 via two lowpass RC filters, one set to about 15Hz and the other to 3Hz. As a magnet passes over the coil, a potential difference is created at IC2’s inputs, causing the output to swing towards the positive rail. siliconchip.com.au November 2006  63 Circuit Notebook – Continued PICAXE to LCD interface Liquid crystal displays are often a convenient way of displaying information in PICAXE projects. While it’s possible to purchase an LCD kit that interfaces with your PICAXE via a serial link, it’s sometimes cheaper and more convenient to incorporate the display right into your project. Lets’ see what’s involved. LCDs come in all sizes and configurations. Of these, the 16-character by 2-line alphanumeric type was chosen here, as it’s the cheapest and most readily available. Most alphanumeric LCDs use a common interface, as defined many years ago by Hitachi and used in their HD44780 LCD controller chip. The hardware interface is composed of three control lines (R/W, RS and E) and eight data lines (DB0-DB7). Two more lines provide power (VDD) and ground (VSS) to the logic section, while a third (VO) supplies the bias voltage for the display portion. Some displays include LED or EL (electroluminescent) backlightling, which also requires both power and ground connections. 64  Silicon Chip The circuit shows how to connect an LCD module to the PICAXE-18X. As you can see, only four of the eight data lines are connected. This is made possible by using the LCD’s 4-bit “nibble” mode, when 8-bit data is transferred in two 4-bit chunks. In addition, the R/W (Read/Write) line is tied permanently low, as the vast majority of applications need only write to the module. Note that some versions of the PICAXE “Electronic Interfacing Circuits” manual shows the module’s data lines wrongly connected (ie, reversed). In addition, the unused data lines (DB0-DB3) are wired directly to ground, which may cause damage to the module if the R/W line is accidentally pulled high or left floating. Instead, the unused data lines should be connected to ground via 10kW resistors or simply left disconnected. All connections between the PICAXE and LCD are made via 330W resistors. These provide a measure of protection from wiring errors and high-voltage transients. If the wiring is relatively short (say, about 100mm or less) and you’re confident about the accuracy of your connections, then they can be safely omitted. The circuit also includes a simple 3-terminal regulator circuit based on a 7805, to allow operation from a 9-12V DC plugpack. Program description To initialise the LCD controller as well as to move the character display position and perform other housekeeping functions, the PICAXE must write the appropriate commands (instructions) to the LCD. On the other hand, to send an ASCII character for display, the PICAXE must write data to the LCD. The differentiation between commands and data is made with the RS line. This line must be driven high before sending a command and low before sending data. Once the RS line has been correctly set and the data presented on the DB4-DB7 inputs, the E line is pulsed high to latch the data into the LCD controller. This series of tasks can be performed by a few simple subroutines, all of which are present in Listing 1. This listing also shows how the routines are used to display a string (in this case, “HELLO WORLD”) on the LCD. You can incorporate these routines into your projects whenever you want to use an LCD. However, you must not use byte variables b12 or b13 or word variable w7 in any other siliconchip.com.au Listing 1 part of your program. The routines in question are labelled LCD_INIT, WRCMD and WRCHR. Let’s look at each of these in a little more detail. The INIT_LCD routine initialises the module, setting various parameters such as font size (5x7 pixels), number of lines (2), interface data length (4-bit) and so on. An initial pause of 200ms allows the LCD to settle after power-up. A series of commands is then sent in a specific order, deliberately timed in accordance with the module’s datasheet specifications. Readers who want to fully understand the initialisation procedure will find more information in their LCD’s datasheets. The WRCMD routine is not a separate routine per se. Instead, it should be considered part of WRCHR; it simply clears the RS bit so that the byte in LCD_ch will be written to the LCD’s command (instruction) register. Reproduced from the PICAXE manual, Table 1 shows a summary of valid commands that can be sent to the LCD using WRCMD. The WRCHR routine writes the command or data (character) in the LCD-ch variable to the LCD. As described earlier, the byte is written as two 4-bit nibbles. First, the upper nibble is formatted and presented on the output port using the pins command. The pulsout command then strobes the E bit to latch the data into bits DB4-DB7 of the LCD controller’s data register. The lower nibble is then shifted to the high position by multiplying it by 16 and the same sequence followed to write it to the LCD. As mentioned, the RS bit determines a command or data write, so it must be set correctly before the pulsout command. This is achieved in each case by ORing the RS_bit variable in the pins command expressions. Note that you cannot directly call the WRCHR subroutine with a numerical value in variable LCD-ch. Instead, numbers must first be converted to individual ASCII characters. Listing 2 provides an example of how this can be achieved. Alphabetic characters do not require manipulation, as they are already stored in ASCII format. Peter Burgess, Lavington, NSW. ($50) siliconchip.com.au ; LCDDrive.bas ; PICAXE-18X symbol symbol symbol symbol symbol RS = 2 EN = 3 MEM = b11 LCD_ch = b12 RS_bit = b13 ;0 = Command 1 = Data ;0 = Idle 1 = Active ;used when reading EEPROM ;byte to be written to LCD ;RS bit START: gosub INIT_LCD ;always initialise LCD first! eeprom 0,(“ Hello World “) eeprom 16,(“- Test Message -”) ;store text in EEPROM ; Set display position to start of first line Listing 2 DISPLAY: LCD_ch = $80 gosub WRCMD ; Convert number in b0 to ASCII and display it DISPLAY_NUM: LCD_ch = b0 / 100 + $30 gosub WRCHR b1 = b0 // 100 LCD_ch = b1 / 10 + $30 gosub WRCHR LCD_ch = b1 // 10 + $30 gosub WRCHR return ; Display the first line for MEM = 0 TO 15 read MEM,LCD_ch gosub WRCHR next pause 500 ;get 100’s digit ;write to LCD ;get remainder ;get 10’s digit ;write to LCD ;get remainder (units digit) ;write to LCD ; Set display position to start of second line LCD_ch = $C0 gosub WRCMD ;second line starts at $40, not $10! ;(see PICAXE manual for details) ; Display the second line for MEM = 16 TO 32 read MEM,LCD_ch gosub WRCHR next pause 500 goto DISPLAY ; Initialise the LCD module INIT_LCD: pause 200 RS_bit = $00 pins = %00110000 pulsout EN,1 pause 10 pulsout EN,1 pause 1 pulsout EN,1 pause 1 pins = %00100000 pulsout EN,1 pause 1 LCD_ch = $28 gosub WRCMD LCD_ch = $0C gosub WRCMD LCD_ch = $06 gosub WRCMD LCD_ch = $01 gosub WRCMD return ;200ms power-on delay ;clear RS to send command ;command (sets 8-bit mode initially) ;give a 10us pulse on E ;wait 10ms ;give a 10us pulse on E ;wait 1ms ;give a 10us pulse on E ;wait 1ms ;command (now set 4-bit mode) ;give a 10us pulse on E ;wait 1ms ;command (4-bit, 2 lines, 5x7 mode) ;command (display on, cursor off) ;command (increment, no shift) ;command (clear display) ; Write a command (instruction) to the LCD WRCMD: RS_bit = $00 ;clear RS to send command ; Write command or data to the LCD WRCHR: pins = LCD_ch & %11110000 | RS_bit pulsout EN,1 pins = LCD_ch * 16 | RS_bit pulsout EN,1 RS_bit = %00000100 pause 5 return ;put high nibble out first ;give a 10uS pulse on E ;put low nibble out next ;give a 10uS pulse on E ;default (to send data) ;wait 5ms Table 1 - LCD Module Commands 1 Clear display and move to the start of the first line    2 Move the cursor and display ‘window’ to the start of the first line    4 Set ‘right to left printing’ mode    5 Set ‘scroll printing to the left’ mode    6 Set ‘left to right printing’ mode    7 Set ‘scroll printing to the right’ mode 10 Turn visual LCD screen off 12 Hide cursor 13 Make cursor flash 14 Turn visual LCD screen (and cursor) on 16 Move cursor left one position 20 Move cursor right one position 24 Scroll display ‘window’ left one position 28 Scroll display ‘window’ right one position 128 Move cursor to the start of the first line 192 Move cursor to the start of the second line November 2006  65 Circuit Notebook – Continued PICAXE-controlled Yoghurt maker You can make you own yoghurt with the help of this simple heating and cooling gadget. It’s based around a PICAXE microcontroller, two power relays and a multipurpose heating/ cooling assembly (PELT2) from Oatley Electronics – www.oatleye.com. The heating/cooling assembly is driven by a thermoelectric cooler that utilises the Peltier effect. These units were originally intended for water coolers and are supplied complete with a 1-litre plastic water reservoir. First, the top of the reservoir and its internal baffles must be removed and the bottom spout cut off and sealed so that it will stand. A replacement lid can be fashioned from a Styrofoam box or similar. A new baffle cut from a plastic lid (see accompanying diagram) can then positioned in front of the Peltier module and wedged in the corners to hold it in place. The existing thermistor must also be replaced with a DS18B20 temperature sensor. For best results, an additional 12V DC fan can be positioned inside the reservoir to circulate air over the Peltier module and around the enclosure. The modified assembly is driven with the circuit shown here, which in effect operates like a simple thermostat. A PICAXE-08M microcontroller (IC1) strives to maintain the internal temperature at 35-37°C, using relay RLY1 to control power to the Peltier module and a DS18B20 temperature sensor for feedback. This is the multipurpose heating/ cooling assembly (PELT2) from Oatley Electronics. 66  Silicon Chip siliconchip.com.au Listing: Yogurt Maker Mathew is this m Tiede onth’s winne Peak At r of a las Instrum Test ent The airflow also falls under PICAXE control, using transistor Q1 to switch both the heatsink-attached fan and the circulation fan. In addition, a double-pole, double-throw relay (RLY2) allows the micro to control the polarity of the voltage applied to the Peltier, so the assembly can be commanded to heat or cool the yoghurt culture. Power for the micro and associated components is provided by a 78L05 3-terminal regulator. Diode D1 adds reverse polarity protection to the input. Together with the 470mF capacitor, it also acts to isolate the circuit from the high-current supply to the Peltier unit. Zener diode ZD1 and its 10W series resistor limit positive transients, while the 220nF capacitor across the contacts of RLY1 suppresses highfrequency noise components at their source. A 12V DC power supply with good load regulation and at least a 9A capacity should be used to power the assembly. Be sure to use only extraheavy duty wire for the Peltier module and relay wiring, as indicated by the heavy outlines on the circuit. Power for the microcontroller circuit must not be picked off at some point along the Peltier wiring. Instead, it must be independently wired to the power supply output terminals (as shown) to ensure reliable operation. To make the yoghurt, the author uses a heaped tablespoon of “Easiyo” premix in a clean, warmed 375ml glass jar half-filled with tepid water. Add four heaped tablespoons of ordinary dry milk powder and combine until smooth. Add warm water to the top of ' Yoghurt Maker by M.Tiede 08/06 ' PICAXE-08M symbol TOPTEMP = 37 symbol BOTTEMP = 35 'upper temp 'lower temp 83mm symbol temp = b10 ' pin definitions 125mm NEW INTERNAL BAFFLE This diagram shows the details for the new baffle which is positioned in front of the Peltier module. the jar, seal and place in the modified reservoir. The unit is now ready for operation. Note that in use, the polarity relay (RLY2) should not continually cycle on and off. If it does, this indicates that the system is continually overshooting the target temperature. Experiment with the pause time in the “loop” section of the program, air circulation in the reservoir and fan run time to reduce overshoot. Depending on a number of variables, the yoghurt will set from 3-9 hours, after which is should be chilled. The new yoghurt can then be used as a starter for the next batch; simply remove a teaspoon full, place it in a clean jar and refrigerate for subsequent making. Save the remaining open premix in your freezer. Once you’ve got the unit set up correctly and know the typical run time, it might well be possible to have symbol FAN = 0 symbol PWR_RLY = 1 symbol POL_RLY = 2 symbol DS18B20 = 4 'circulation/heatsink fans 'power relay (RLY1) 'polarity relay (RLY2) 'temp sensor main: low FAN low PWR_RLY 'fan off 'Peltier off loop: pause 5000 'to check temp every 5 secs readtemp DS18B20,temp 'get current temp if temp > TOPTEMP then toohot if temp < BOTTEMP then toocold goto loop toohot: high FAN high POL_RLY high PWR_RLY pause 100 less: readtemp DS18B20,temp if temp > TOPTEMP then less goto main toocold: high FAN low POL_RLY high PWR_RLY pause 100 more: readtemp DS18B20,temp if temp < BOTTEMP then more goto main 'turn on the fan 'set correct polarity for cooling 'power up the Peltier 'settling time 'get current temp 'loop until cool enough 'turn on the fan 'set correct polarity for heating 'power up the Peltier 'settling time 'get current temp 'loop until warm enough the unit chill your yoghurt ready for breakfast! Mathew Tiede, Gympie, Qld. C h o o s e Yo u r P r i z e There are now five great reasons to send in your circuit idea for publication in SILICON CHIP. We pay for each item published or better still, the best item in “Circuit Notebook” each month will entitle the author to choose one of four prizes: (1) an LCR40 LCR meter, (2) a DCA55 Semiconductor Component Analyser, (3) an ESR60 Equivalent Series Resistance Analyser or (4) an SCR100 Thyristor & Triac Analyser, with the compliments of siliconchip.com.au Peak Electronic Design Ltd. See their website at www.peakelec.co.uk So now you have even more reasons to send that brilliant circuit in. Send it to SILICON CHIP and you could be a winner. You can either email your idea to silchip<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. November 2006  67 By PETER SMITH Rev ie w : BitScope BS310 mixed-signal oscilloscope This versatile data acquisition system packs a digital oscilloscope, spectrum analyser, logic analyser, data recorder and waveform generator into one affordable package – and it’s Australian-designed and supported! PC-BASED TEST instruments are nothing new. By using the processing power and graphical interfacing capabilities of the PC, manufacturers have been able to dramatically improve the price/performance ratio of their test equipment. The advantages of combining test equipment with the power of the PC are not lost on Australian company BitScope Design, who manufacture a small range of mixed-signal oscilloscopes and accessories. BitScope first appeared in 1998, when Australian design engineer Norman Jackson described his “Mixed Signal Capture Engine” in the pages of Circuit Cellar. He won first prize in a competition for his efforts. Subsequently, BitScope went on to offer several designs as do-it-yourself 68  Silicon Chip kits. These proved to be very popular but have been recently discontinued, as several through-hole components used in the kits are no longer available. The current models all use surfacemount technology and are therefore sold preassembled and tested. Despite the shift to preassembled units, the same core principles apply to all BitScope instruments. Their “open design” policy means that all units are supplied with circuit diagrams so that you can see how they work. In addition, detailed architectural information is provided on the BitScope website for those that wish to write their own virtual instrumentation applications. BS310 captured We test-drove BitScope’s BS310U model. It’s housed in a small, extruded aluminium case and features a dualchannel, 100MHz (40MS/s) analog and 8-channel logic data capture engine. Analog and logic data are sampled simultaneously and stored in local 128kS buffers prior to high-speed transfer to the PC via a USB (BS310U model) or Ethernet (BS310N model) connection. An arbitrary waveform generator (AWG) adds significant versatility to the instrument’s capabilities. The AWG can generate single, pulsed or continuous waveforms of up to 128kS at 10MS/s and can operate through BNC channel B. Importantly, it can function concurrently with the capture engine, thus allowing a circuit to be stimulated and its response observed in real time. Processing and display of raw data from the BS310 is performed by BitScope’s “DSO” software running on Windows or Linux. This combines a complete set of virtual instruments under a common user interface: a digital storage oscilloscope, spectrum analyser, logic analyser, data recorder and waveform generator. siliconchip.com.au Fig.1: all virtual instruments run in a common graphical interface called “DSO”, shown here with the oscilloscope and spectrum analyser enabled. Both analog channels are displayed, with channel B sourced from the pod input. Many parameters are alterable by clicking on left, right, up or down arrows. Some can also be modified by right-clicking on the parameter and choosing from a predefined list that pops up. Others simply allow you to enter a value directly. DSO’s virtual instruments enjoy the benefits of the host’s processing power and data storage. Additionally, the software automatically adjusts to accommodate the large, widescreen displays now common on many PCs. Simply put, you get to see a lot more of the signal at a time than would ever have been possible with a standalone instrument! More on the box Most of this review focuses on the software side of the package but before we get into that, let’s look briefly at the front panel connectors and switches, the logic pods and some of the more notable hardware features not yet mentioned. The two front-panel BNC inputs can be terminated with 1MW or 50W, selectable via miniature toggle switches. Signal coupling may be AC or DC and is software selectable. When needed, input sensitivity can be increased 10 or 50-fold by enabling an analog input multiplier, again under software control. Also of note is the programmable triggering logic for both the analog and digital channels. Moreover, a cross-triggering function allows the digital trigger to operate from the analog (A/D converter) output, making siliconchip.com.au Fig.2: here we’ve running three instruments simultaneously – the waveform generator, oscilloscope and spectrum analyser. Channel B shows the generator’s output, which is a 5kHz, 4V square wave. Channel A is measuring an LC tank circuit stimulated with the square wave. Using the cursors, we can see that the tank circuit oscillates at about 33.6kHz. Check out the BitScope website for a similar, more detailed example in the AWG section of the Online User Guide. this instrument extremely useful for mixed-signal work – a normal requirement in today’s electronics. A 25-pin “D” connector on the front panel gives access to all eight of the digital logic inputs and provides two alternate analog inputs as well. For low-speed work, this connector can be wired directly to the logic circuits under test. However, in most cases, one of BitScope’s optional logic pods is required to interface the test signals to the BS310’s inputs. The basic pod consists of a small circuit board that carries a HCMOS buffer chip and a few passive components and is +5V and +3.3V TTL/CMOS logic compatible. 26-way header plugs mount on opposite edges of the board. One plug connects to the front-panel “D” connector via a short length of ribbon cable, while individual “E-Z hook” style leads are pushed onto the desired signal input and ground pins on the other plug for connection to the circuits under test. Power supply and serial I/O lines are provided on the “D” connector for those wanting to design a custom “smart” pod for specialised applications. In fact, BitScope offer the “ProtoBoard” for just such a purpose. This board plugs directly into the “D” connector and offers a conveni- ent, low-cost platform for 18-pin PIC development. DSO software As mentioned, all of the DSO’s virtual instruments run under one common user interface. Individual instruments are enabled via a row of selection buttons on the right side of the DSO window. In some cases, more than one instrument can be active at a time. For example, either the spectrum analyser or logic analyser can operate concurrently with the oscilloscope. In these cases, the waveform display area is automatically divided in half to accommodate both instruments. Once the desired settings have been made, most of the controls can be hidden to maximise the waveform display area, if desired. OK, lets’ look briefly at each of the major components of the software, starting with the oscilloscope. Digital storage oscilloscope The oscilloscope display is laid out on an 8x10 grid. The horizontal and vertical scales are not displayed against the X and Y-axes but instead are determined from a list of “information variables” that appear immediately below the graticule. November 2006  69 Fig.3: in mixed signal mode, one analog channel and all eight digital channels are displayed in a time-aligned fashion. With the aid of the cursors, it’s easy to relate events between the domains. Vertical settings range from 500mV to 5V in familiar 1-2-5 steps. This is separate from the analog input range, which can be set to 513mV, 2.35V, 4.7V or 10.8V with the multiplier off. With the multiplier set to x50, the selections shrink to 10.3mV, 47mV, 94.1mV or 216mV. Naturally, the idea is to set the input range to maximise resolution, taking into account the amplitude of the input signal. The latest version of DSO does this automatically, although the settings can still be altered independently if desired. The vertical settings also cater for probe type (x1, x10, x100 of x1000), input signal multiplier (OFF, x10 or x50) and coupling (AC or DC). The signal can be sourced from the pod rather than the BNC input by clicking on the “POD” button and can be inverted by clicking on “INV”. Dragging a slider or clicking on BitScope’s basic logic pod consists of a small circuit board that carries a HCMOS buffer chip and a few passive components and is +5V and +3.3V TTL/CMOS logic compatible. 70  Silicon Chip “up” and “down” arrows alters trace position. The BitScope engineers have obviously put some thought into these controls, because despite their small size they’re quite easy to use. The horizontal timebase is straightforward, with settings ranging from 10ns to 500ms, again in 1-2-5 format. DSO automatically dials in the appropriate sample rate each time the timebase is altered. A “zoom” setting directly above the main timebase slider allows horizontal zooming of up to 50 times. Panning through the display buffer to find the section of interest can then be achieved by dragging the waveform offset slider just below the graticule. DSO includes a second, delayed (or “zoom”) timebase that is indispensable when you want to examine a small section of a repetitive waveform in detail. A shuttle control eliminates the need to fiddle with manual parameters when trying to find the segment of interest, which is highlighted in the main timebase display by a grey band. Once the area of interest is identified, a click on the “ENABLE” button brings the segment into full view. Slick indeed! Analog triggering is fully featured and can be set to rising or falling edge. It can also be filtered and can have a hold-off period programmable from 3ms to 150ms. In addition, a pre-trigger feature allows the position of the trigger in the captured data to be selected from 0%, 25%, 50%, 75% and 100% of the buffer. Spectrum analyser In keeping with the ease-of-use mantra, DSO features a fully automatic spectrum analyser (FFT). For the mathematically clued, it utilises a variable size windowed DFT processing engine suitable for both one-shot and periodic waveforms and is capable of displaying spectra from DC to over 100MHz. The time and frequency displays share the same data source and therefore the same timebase and trigger. This means that the spectrum analyser instrument can operate simultaneously with the oscilloscope, if desired. Clicking the “BOTH” selection button splits the display in half, with the top half showing the spectra and the bottom half the oscilloscope. Measurements within the time and frequency domains can be made with the aid of “X” and “Y” cursor pairs, which are simply enabled with a mouse click and then dragged to the desired points of interest on the waveform. Values such as period, pulse width, slew rate, frequency and bandwidth are all readily determined. Logic analyser The logic analyser operates in what is known as “mixed” mode. The top half of the waveform display area shows oscilloscope inputs A or B (only one analog channel can be used in this mode) and the bottom half the eight analyser traces. However, it’s also possible to enable only the logic analyser (or oscilloscope) portion of the display for easier interpretation. This instrument operates synchronously with the oscilloscope and so shares the same timebase settings. Triggering can be on any logic state, with each bit definable as high, low or “don’t care”. Crucially, the trigger can also come from one of the analog channels, providing the cross-triggering function we mentioned earlier. The BitScope literature makes a big deal out of the product’s mixed analog and digital logic display and crosstriggering capabilities – and with good reason! Just about all electronics these days incorporates both domains, so the ability to see them working together is indispensable. Waveform generator This instrument operates much like a conventional signal generator, supporting sine, step and ramp functions. Frequency, symmetry, amplitude (up to 10V) and offset are all fully programmable. Using a front-panel toggle switch, siliconchip.com.au the AWG output can be directed to the channel B input, so there’s no need to probe the circuit to see the waveform. The second analog channel is free to measure circuit response. The above holds true when the AWG is set to produce repeating oneshot waveforms. However, when set to produce continuous waveforms like a dedicated AWG, no other virtual instrument can be used at the same time. Data recorder Analog and logic waveforms can be recorded to disk using the DSO Data Recorder (DDR) instrument. Data is saved in “CSV” file format, so is compatible with all popular analysis tools such as MatLab and Excel. This handy feature allows records to be instantly replayed for comparison with newly captured data. A brand new function in DSO even allows the waveform data to be loaded when no BitScope hardware is connected. So yes, you can now take your work home with you! BitScope BS310 Specifications Summary Analog Inputs................................................................2 x BNC or 2 x POD Analog Bandwidth.............. 100MHz (see product specifications for details) Input Impedance.............................. 1MW||20pF (BNC), 100kW||5pF (POD) Input Voltage Range..... ±513mV to ±10.8V & ±5.13V to ±108V (x10 probe) Input Multiplier Gain.......................................x10 and x50 (user selectable) Analog Sensitivity...............................................................2mV - 40mV (x1) Maximum Sensitivity......... 300mV (time), 70mV (frequency) & 10mV (mean) Fast Sample Rates................................ 4, 5, 10, 13.5, 20, 25, 33 & 40MS/s Slow Sample Rates.......................... 4kHz – 1MHz (slow) and < 1Hz (burst) Channel Buffer Depth.................................. 128kS (analog) + 128kS (logic) Glitch Capture....................................................................................... 25ns BitScope Digital Trigger................ 8-bit combinatorial on logic or A/D output High Speed Analog Trigger..................................................................... Yes Waveform Generator.............. 10MS/s (switchable through BNC channel B) Data upload speed................................................................. 1.2Mb/s (max) PC Host Interface..................................USB 2.0 (also USB 1.1 compatible) or 10BaseT Ethernet Size..............................................................150 x 55 x 100mm (W x H x D) Look & feel Virtual instrument designers must be tempted to pack in every conceivable feature to make their products more appealing. After all, one of the big advantages of a software-based interface must be that it doesn’t cost near as much to add a function as it would in a hardware-dominated product. But would such a feature-laden beast really be usable? Probably not! And this is what we liked most about this system. Everything that you want is right there in front of you – there’s no need to go fishing through the menus (or God forbid, the manuals) to get the job done. Waveforms can be displayed in “raw”, “wideband” or “enhanced” formats and can even be given phosphorlike qualities of persistence for viewing eye patterns, spectral plots and the like. In fact, DSO’s waveform rendering and signal processing produces an image on screen that’s not unlike a conventional analog scope and must be one of the best we’ve seen. Check it out As with any test system of this nature, it’s difficult to get a feel for the product unless you actually have it in your hands. BitScope have tried to make evaluation easier by connecting a siliconchip.com.au BitScope to the Internet, where anyone can get access to it. To get connected, first download and install the latest version of DSO from www.bitscope.com. Next, launch the software and click on the “SETUP” button. On the “Setup” tab, select a connection type of “ETHERNET” and an IP address of “SYDNEY”. It’s then just a matter of hitting the Fig.4: triggering in mixed signal mode can original from an analog channel or the logic channels. For logic triggering, the state of each bit determines the trigger – in this case, 010X10XX (X= don’t care if high or low). “POWER” button to make the connection to the BS300N model at BitScope’s Sydney office. Watch out though – someone else might be fiddling with the controls, too! Note: your firewall rules must allow UDP connections on port 16,385 ($4001) for BitScope communication over the Internet. Final thoughts Unfortunately, we can’t hope to cover every feature of DSO or indeed the BS310U in this short review. Although it’s already a mature product, BitScope continue to develop their DSO software, as can be seen with the addition of their “Waveform Intuitive Display Engine” (WIDE) in the latest release. We’ll leave it up to you to discover exactly what WIDE can do! At time of publication, the BS310U was priced at $650.12 plus GST and delivery. Scope probes and logic pods are not included in the price but can be ordered separately. Other models, including a larger quad-channel version, are also available. Check out www.bitscope.com for all the details or phone (02) 9436 2955. If you live in Sydney, you can drop into their office at G03/28 Chandos SC St, St. Leonards. November 2006  71 Salvage It! BY JULIAN EDGAR Using the convex lenses from fancy car headlights Good quality convex lenses can be salvaged for next to nothing from car wrecking yards. Here’s how to use them to make a really bright handheld spotlight or a broad-beam bike light. W HEN YOU WATCH cars go by at night, you can see a variety of headlight designs on display. For example, old cars use sealed beams which are often rather yellow in appearance. Then there are the whiter designs with replaceable halogen bulbs, while recent luxury cars feature high intensity discharge lights which have a brilliant blue/white colour. Projector headlights There are also lights which, when viewed at an angle, have red or blue beams graduating to white as the car is seen face-on. These headlights have an abrupt beam cut-off and a very even spread of light within the beam. They are known as “projector” headlights and use a simple reflector teamed with a large convex glass lens. Want to know something? Those A projector headlight is easily recognised because of its convex glass lens. 72  Silicon Chip large glass lenses can be obtained for nearly nothing from broken headlights at car wreckers. Want to know something else? They make excellent lenses for use in bike lights, torches and handheld spotlights. Fig.1 shows a typical projector car headlight. From the front, there’s a cover plate of glass or plastic. Behind that is the convex glass lens (normally used only on low beam), followed by the bulb and then a simple reflector. The bulb is masked so that the upper part of the beam is abruptly cut off, to avoid blinding oncoming drivers The single headlight assembly also contains a high beam, which usually comprises a conventional halogen lamp and a reflector. The headlight is near worthless to the wrecker if the cover glass is broken, the high beam is broken, the low beam is broken or the rear plastic housing is shattered. However, if the low beam convex glass lens is intact, the convex lens can be bought for next to nothing. For example, at a major wrecking yard, I found and salvaged three convex lenses and took them to the front counter. I made the point that I hadn’t needed to break any headlights to obtain the lenses and asked for a price. The man behind the counter was puzzled: what on earth did I want these lenses for? I told the truth – I was making a bicycle headlight – and he charged me $10 for all three. On another occasion, when I was buying some other car bits, the convex lens didn’t cost me anything extra. Many recent cars have projector headlights while amongst older cars, the Mazda 626 and Ford Telstar are the siliconchip.com.au Large convex glass lens are easily salvaged from wrecked car headlights that use a “projector” design. These lenses use high transmission glass and are optically accurate. most common. Some Nissan imports also have them, including one car that has two such lenses each side. If you are salvaging the lens from a headlight with a broken cover glass, be very careful. It is extremely easy to cut yourself on the shards of glass, especially if you slip while wielding a screwdriver. Incidentally, smaller lenses of a similar shape can also be salvaged from old slide projectors. Using the lens So you have a bunch of high-quality, large, convex glass lenses that you’ve obtained for nearly nothing. Now what? I could get all theoretical and talk about focal lengths and beam angles and point sources but let’s forget all that. The easiest way of coming up with the best design for your particular application is to simply play around with the light source and the different lenses. For example, a Luxeon LED makes an excellent light source as it is small, very bright and has high efficacy. Power-up the LED (after mounting it on a suitable heatsink if it’s a 3W or 5W design) and hold the convex lens in front of it. Now view the beam pattern on a wall or the ceiling. By altering the distance between the lens and the LED, it’s possible to change the beam from a broad diffuse beam to a narrow spot. In the case of the Luxeon, you can also try matching the glass lens with the various collimators available for these LEDs. The lenses can also be used with siliconchip.com.au This photo shows the components needed for a bright, wide-angle light (from left and then clockwise): convex glass lens salvaged from a projector car headlight; shortened stainless steel drinking cup and bracket made from aluminium angle; and a 1W Luxeon LED and narrow angle collimator mounted on a salvaged aluminium block. Missing from this photo is a cut-down U-PVC plumbing cap to hold the lens in place over the end of the cup. Fig.1: this diagram shows a “projector” type car headlight. The main optical element is a large convex glass lens mounted within the headlight assembly (1) and this replaces the reflector and flat glass lens used on other headlights. A shield (2) prevents on-coming driver glare, while (3) is the rudimentary headlight reflector and (4) is the bulb. [Bosch] conventional incandescent bulbs and reflectors (and incidentally, lots of working torches with perfectly good reflectors are thrown away each day). Again, it’s a case of trying different combinations and looking at the results. If the lens is placed very close to the light source, it’s possible to get an extremely broad beam, which greatly November 2006  73 The Luxeon LED, its collimator and the mounting block are attached to the base of the cup using screws and nuts. The convex lens fits over the mouth of the cup to provide a broad, even beam. enhances its visibility at night. It’s just the shot for a flashing warning light or bicycle tail-light. Building a compact light I used a convex lens from a car headlight to make a very bright, broad beam, flashing tail-light for a bike. First, a stainless steel drinking cup was shortened in length using a hacksaw and file. This gave a housing with an opening that matched the diameter of the lens. A 1W red Luxeon LED and a narrow-beam collimator were then installed on a small block of alu- They’re Glass The convex lenses salvaged from car headlights are made from high quality optical glass. So if you drop them, hit them or squeeze them hard enough, they’ll shatter! Here the lens has been reversed compared to its normal automotive orientation, with the curved (convex) side facing the light source. This design is being used as a rear light on a road-going recumbent pedal trike. minium (a 1W Luxeon doesn’t need a heatsink but having one doesn’t hurt), after which the block was mounted in the base of the cup. Next, a U-PVC plastic pipe cap to suit the diameter of the lens was obtained and its inner diameter cut out with a holesaw. This gave a flange that fitted over the end of the cup, holding the lens in place. Silicone sealant was then used to secure the cap in place and to weatherproof the opening. In this application, the best results were obtained by reversing the lens as compared to its normal car orientation – ie, it was mounted with the convex part of the lens facing the LED. The Luxeon LED was powered by a 12V cigarette lighter phone charger adaptor which was modified to act as a constant current source (see “Cheap 1W Luxeon LED Driver” on page 101 of the August issue of SILICON CHIP). A modified “Nitrous Fuel Controller” Rat It Before You Chuck It! Whenever you throw away an old TV (or VCR or washing machine or dishwasher or printer) do you always think that surely there must be some good salvageable components inside? Well, this column is for you! (And it’s also for people without a lot of dough.) Each month we’ll use bits and pieces sourced from discards, sometimes in mini-projects and other times as an ideas smorgasbord. And you can contribute as well. If you have a use for specific parts which can 74  Silicon Chip easily be salvaged from goods commonly being thrown away, we’d love to hear from you. Perhaps you use the pressure switch from a washing machine to control a pump. Or maybe you have a use for the highquality bearings from VCR heads. Or perhaps you’ve found how the guts of a cassette player can be easily turned into a metal detector. (Well, we made the last one up but you get the idea . . .) If you have some practical ideas, write in and tell us! Stainless Steel Cup As detailed in the main text, a stain­less steel drinking cup makes an excellent housing for the convex lens. Single wall stainless steel drinking cups can now be very hard to find but Coastal Kitchen and Cutlery on the Gold Coast (07 5526 9399) have them in stock at $5.50 each. A double wall (ie, insulated) cup can also be used but it is heavier and a little more difficult to cut and drill. circuit (from in SILICON CHIP’S High Performance Electronics for Cars) was used to flash the LED. Modifying the Nitrous Fuel Controller is simple – all you have to do is substitute a 2.2mF 16V capacitor for the original 220nF timing capacitor. This gives a flash rate of about 4Hz, with the duty cycle of the flash able to be altered by the on-board pot. So why go to all this bother when LED tail-light flashers are cheaply available? Well, you’ve never seen a flasher like this. It is extremely bright from directly behind and can be seen at distances of 500 metres or more. The convex lens creates a broader beam than would otherwise be achiev­ ed, allowing the light to be visible over a much wider angle than just having the LED on its own. This effect is further enhanced by reflections from the internal walls of the stainless SC steel cup. siliconchip.com.au USB Oscilloscope & Logic Analyzer The new generation Scope for the age of microelectronics. 8 Channel 40MS/s Logic Analyzer  Capture digital signals down to 25nS with arbitrary trigger patterns. 3 Input 100MHz Analog DSO  Classic Analog Scope using a standard x1/x10 BNC probe. Additional inputs on the POD for dual channel operation. 8 + 1 Mixed Signal Scope  True MSO to capture an analog waveform time-synchronized with an 8 channel logic pattern triggered from any source. Real-Time Spectrum Analyzer  See the spectrum and waveform of analog signals simultaneously and in real-time Waveform Generator  Load up to 32K arbitrary waveform and replay via the onboard DAC (10MS/s) or a digital pattern from the POD (40MS/s) Standard 1M/20pF BNC Input 200uV-20V/div with x10 probe S/W select AC/DC coupling S/W select 50ohm termination Arbitrary Waveform Generator Turn your PC or NoteBook into a powerful Scope and Logic Analyzer! See inside your circuit in the analog and digital domains at the same time to make tracking down those elusive real-time bugs much easier. Pocket Analyzer combines a high speed sample-synchronized storage scope and logic analyzer with a programmable waveform and logic pattern generator. Also included is an integrated real-time spectrum analyzer and powered "Smart POD" expansion interface so you've got all bases covered! About the same size and weight as a Pocket PC, this USB powered BitScope needs no bulky accessories. It's the perfect low cost "go anywhere" test and debug solution. BitScope "Smart POD" Connector 8 logic channels, 2 analog channels Dual channel capture from POD A/B Async serial I/O for external control Logic Pattern generator 32K 40MS/s BUS Powered USB 2.0 Device Single USB cable to your PC Compressed data transmission Simple ASCII control protocol BitScope Scripting Language External/Passthru Power Supply Auto senses an external supply removes power load from USB for use with unpowered hubs. Supplies up to 500mA via POD BitScope and your PC provide an array of Virtual Instruments • R&D • Education • Robotics • Lab Scope • Fast DAQ • Service • Debug BitScope Pocket Analyzer uses highly integrated Surface Mount technology to provide functionality you would expect from scopes many times the size and price. Its programmable Virtual Machine architecture means new functionality can be added via software. For custom Data Acquisition, export directly to your spreadsheet. BitScope DSO 1.2 software for Windows and Linux siliconchip.com.au BitScope Designs www.bitscope.com Phone: (02) 9436 2955 Fax: (02) 9436 3764 November 2006  75 By JOHN CLARKE Con t r ol h i gh - cur r en t loa ds w i t h t h is DC Relay Switch Want to switch power to a high-current load using a circuit capable of supplying just a few milliamps? No problem – build and use the SILICON CHIP DC Relay Switch. I T’S OFTEN NECESSARY to switch power to a device that requires a current of several amps in order to drive it. The problem is, the device that’s required to do the switching may only be capable of supplying just a few milliamps. Such a circuit might be capable of switching on a LED but that’s about all. The way around this problem is to use a relay with heavy-duty contacts to switch the power. However, your electronic switching circuit may not even have sufficient power to drive a relay coil – at least not directly. This DC Relay Switch board is the answer to that type of situation. It utilises a heavy-duty relay with 30A Main Features • • • • • • • • Automotive-style high-current relay Operates from 12V DC power supply Suitable for low-voltage switching only (up to 50V DC) Activated by low current Isolated input to provide flexible switching options Can be activated using a low-voltage AC signal or an oscillating signal Relay-on LED indication Normally open (NO) and normally closed (NC) relay output terminals 76  Silicon Chip contacts, runs from a 12V supply and requires just 400mA of signal to trigger the relay. That’s made possible by using an optocoupler and some simple electronic circuitry to drive the relay. What’s more, the input trigger signal does not have to be ground referenced. This means that you can drive the relay board from just about any DC signal, whether it normally sits at around 12V, 5V or 0V. It can even be driven by low-voltage AC or by a signal that is rapidly switching on and off. Current drive In practice, the DC Relay Switch requires a current to drive it rather than a voltage. A signal current of just 400mA or more switches the relay on and when there is no current, the relay switches off. In practice, this means that you can drive the relay switch board using an external circuit that normally drives a LED. When the LED is on, the relay is on and vice versa. Alternatively, the relay board can be connected so that the relay is off when the external LED is lit. If the LED is multiplexed (ie, switch­ ed on and off) at a fast rate, then the relay board can be configured to switch on the siliconchip.com.au Parts List Fig.1: the circuit is triggered by applying a signal to optocoupler OPTO1. When the phototransistor in OPTO1 turns on, it turns on transistor Q1 and this then turns on transistor Q2 which drives the relay and LED1. relay while ever the LED is being driven by the switching circuitry. A LED on the DC Relay Switch board provides on/ off indication for the relay (ie, it lights when the relay switches on and goes off when the relay is off). As shown in the photos, the DC Relay Switch comprises a small PC board that includes the relay, the optoisolator, two transistors and various other minor components. It is powered from a 12V DC supply via an on-board screw terminal block. A second 2-way screw terminal block is used for the trigger signal inputs. External connections to the relay contacts can be made using either PCmount spade connectors or a 3-way screw terminal block. The spade connectors are best for high-current applications. Finally, the PC board can be fitted inside a small plastic (UB5) utility case, if this is required. OPTO1 from breaking down and dissipating too much power if a reverse voltage is applied. In this case, D3 conducts and limits the voltage across the LED to a safe value (ie, to about 0.6V). When current flows in the optocoupler LED, the optotransistor conducts and supplies base current to transistor Q1 via the 22kW resistor from the 12V supply rail. This switches Q1 on which in turn switches Q2 on via its associated 1kW base resistor. And when Q2 switches on, relay RLY1 also switches on, as does LED1. The 10kW resistor between Q1’s base and ground ensures that Q1 switches off when the phototransistor in OPTO1 turns off. Similarly, the 1kW resistor between Q2’s base and emitter ensures that this transistor switches off when Q1 switches off. The 1mF capacitor on Q1’s base is necessary if the input is driven using How it works OK, let’s see how the circuit works – see Fig.1. As shown, the input trigger signal is applied to the LED inside optocoupler OPTO1 via a 1kW resistor. This resistor limits the LED current to less than 12mA for a 12V signal and to less than 5mA for a 5V signal. Diode D3 prevents the LED inside siliconchip.com.au 1 PC board, code 05211061, 46 x 61mm 1 UB5 box, 83 x 54 x 31mm 1 SPDT PC mount horn relay (Jaycar SY-4072, Altronics S 4206A or equivalent) (RELAY1) 2 2-way screw terminal connectors (5.08mm pin spacing) 1 3-way screw terminal connectors (5.08mm pin spacing) 3 PC mount 6.4mm spade connectors 1 2-way pin header (2.54mm pin spacing) 4 M3 x 12mm countersunk Nylon screws & nuts 4 3mm Nylon washers 4 M3 nuts 1 jumper shunt Semiconductors 1 4N28 optocoupler (IC1) 1 BC549 NPN transistor (Q1) 1 BC327 PNP transistor (Q2) 2 1N4004 1A diodes (D1,D2) 1 1N4148 diode (D3) 1 3mm red LED Capacitors 1 220mF 16V PC electrolytic 1 1mF 16V PC electrolytic Resistors (0.25W, 1%) 1 22kW 1 2.2kW 1 10kW 3 1kW an AC signal or some other switching signal. This capacitor is connected into circuit using link LK1 and filters the resulting signal on pin 4 of OPTO1 to produce a steady DC voltage. This ensures that Q1 remains on while ever the input signal is applied. Note that LK1 is only necessary for AC input signals. It can be left out of circuit (ie, the 1mF capacitor is disconnected) for DC trigger signals. Operating The Circuit From 24V DC Want to operate the DC Relay Switch from 24V DC? Here’s how to do it: • • • Use a 24V relay instead of a 12V relay – eg, the Altronics S 4208A 24V 30A relay (Jaycar do not have a 24V version). Increase the voltage rating of all capacitors to 35V. Change the 2.2kW resistor in series with LED1 to 4.7kW 0.25W. November 2006  77 Fig.2: install the parts on the PC board as shown in this layout diagram. Be careful not to get transistors Q1 & Q2 mixed up – they may look identical but Q1 is a BC549 (NPN) while Q2 is a BC327 (PNP). Diode D2 provides spike protection for transistor Q2 when the relay is switched off. It shunts the back-EMF voltage spike generated when the relay switches off – a necessary precaution to prevent “punch-through” of the transistor. Power for the circuit can be derived from any suitable 12V DC supply (eg, a plugpack or battery). Diode D1 provides reverse polarity protection, while a 220mF capacitor decouples the supply. Construction The DC Relay Switch is built on a Warning! DO NOT use this DC Relay Switch to switch 240V AC mains voltages. The relay is not designed to do this and it is dangerous to connect mains to the bare PC board. If you do need to switch mains voltages, then use this board to trigger an external mains-rated relay. A suitable mains switching relay was published in the May 2006 issue of SILICON CHIP. PC board coded 05211061 and measuring 46 x 61mm. This fits inside a UB5 box and is secured using four M3 x 12mm countersink Nylon screws and nuts. A 3mm Nylon washer is used between the PC board and the case at each mounting point, to lift the board clear of the base. Fig.2 shows the parts layout on the PC board. Begin by checking the PC board for any defects such as broken tracks and shorts between adjacent tracks. That done, check the corner hole sizes – these should all be 3mm in diameter. In addition the holes for the relay pins and the screw terminal blocks must be large enough to accept these parts. Once all the hole sizes are correct, begin the assembly by installing the resistors. Table 1 shows the resistor colour codes but it’s a good idea to also check them using a digital multimeter, just to make sure. Next, install the diodes and the optocoupler (OPTO1), making sure they go in with the correct polarity. Follow these with the capacitors, transistors Q1 & Q2, the LED and the relay. Take care with the polarity of the capacitors and LED. Transistors Q1 & Q2 come in iden- tical (TO-92) packages so be careful not to get them mixed up. Q1 is an NPN BC549 type, while Q2 is a PNP BC327 and the circuit won’t work if you transpose them or install them the wrong way around. As mentioned previously, you can use either a 3-way screw terminal connector or PC-mount spade connectors to make the external connections to the COM, NO & NC relay contacts. Use the spade connectors if the relay terminals are to carry currents in excess of 2A via. Finally, install the 2-way pin header for LK1. The link itself can be left out if you intend to trigger the board using a DC input signal. Alternatively, install the link if you want delayed switch-on and switch-off for the relay, or if you intend using an AC input signal (see below). Testing OK, now for the smoke test. You will need a 12V DC supply rated at about 150mA to power the board. Connect this to the +12V and 0V terminals, making sure you get the polarity right. Initially, when you apply power, nothing should happen. You can now Table 1: Resistor Colour Codes o o o o o No.   1   1   1   3 78  Silicon Chip Value 22kW 10kW 2.2kW 1kW 4-Band Code (1%) red red orange brown brown black orange brown red red red brown brown black red brown 5-Band Code (1%) red red black red brown brown black black red brown red red black brown brown brown black black brown brown siliconchip.com.au Fig.3: the various triggering options. In (a) the relay board is triggered by a signal that goes from low to high (+5V or +12V); in (b) by a signal that goes to 0V; and in (c) by an external circuit that turns on an indicator LED. check if the circuit works by connecting the negative (-) signal input to 0V and the positive (+) input to the +12V rail. When you do so, the relay should immediately switch on and the LED should light. How to use it Fig.3 shows three different circuit configurations that can be used to trigger the relay board. Fig.3(a) shows how to turn the relay on using a signal output that goes high (ie, to 5V or 12V). Conversely, Fig.3(b) shows how to rearrange the wiring so that the relay turns on for a signal output that goes low (ie, to 0V). Fig.3(c) shows how to drive the relay board from a circuit that normally powers a LED. Note that if the LED is multiplexed when it is lit (ie, switched on and off at a fast rate), the relay may chatter on and off. Inserting link LK1 to connect the 1mF capacitor into circuit should stop this chattering. In all three above cases, if you want delayed switch-on and switch-off for the relay, increase the value of the 1mF capacitor. A value of 220mF will give a nominal 1-second delay. Note that it is important that the trigger circuit be capable of providing the required current to the relay board input. The relay board will draw about 3mA when there is 5V between its “+” and “–” inputs and 10mA when there is 12V between these terminals. If this exceeds what the trigger circuit can deliver, then the 1kW resistor in series with pin 1 of the optocoupler can be increased. Doubling this resistor (eg, to 2.2kW) will halve the current requirement but if you ultimately go too high in value, the optotransistor may not turn on sufficiently to drive the relay circuit. The minimum recommended trigger current is 400mA. This corresponds to using a 22kW resistor in series with OPTO1 for a 12V power supply and a SC 7.5kW resistor for a 5V supply. Looking for real performance? 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Order by phoning (02) 9939 3295 & quoting your credit card number; or fax the details to (02) 9939 2648; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. siliconchip.com.au November 2006  79 LED Tachometer Com p le t in g t h e c on s t r uc t ion & ch a n gin g t h e s e t t in gs Pt.2: By JOHN CLARKE Setting up the LED Tacho mainly involves stepping through and reprogramming the default software settings in the PIC to suit your vehicle. Here’s how it’s done. H AVING COMPLETED the PC board assemblies and made up the connecting cable as described last month, it’s now time to test the tachometer. However, before applying power, check that all parts are in their correct locations and are correctly oriented. Check also for any solder shorts between the board tracks and IC pads. Do not connect the display PC board to the main board yet – that step comes later, after the initial voltage checks. In addition, the PIC micro (IC3) should be left out of its socket. Once you are satisfied that every80  Silicon Chip thing is correct, apply power (12V DC) to the main PC board and check that pins 4 & 14 on IC3’s socket are at +5V. That done, monitor the voltage at TP1 (with respect to 0V) and check that this voltage can be varied from about 2-5V using trimpot VR1. If this checks out, switch off the power and install IC3 in its socket – see Fig.5 last month. Make sure that this IC is oriented correctly; ie, with its notched end towards the adjacent 100nF capacitor. Next, connect the display board to the main board using the IDC cable, then set VR1 fully anticlockwise and VR6 fully clockwise. Trimpots VR2, VR3, VR4 & VR5 should all be set to mid-position. Apply power and you should be greeted by a single “0” on the digital display (ie, on the righthand digit). In addition, LED1 in the bargraph should light. If this does not happen, switch off immediately and check for assembly errors (ie, parts placement, faulty or missed solder joints, solder shorts between IC pads, etc). Testing the displays Assuming everything is OK so far, you can now test the displays by switching off and then pressing the Up switch (S3) while you re-apply power. If you keep this switch pressed, the display should show all “eights”, with the two far-left decimal points also lighting. In other words, you should see 8.8.88 (do not expect the two righthand decimal points to light). siliconchip.com.au At the same time, each LED on the circular bargraph should light in sequence, followed by the shift LED when the bargraph sequence is completed. The lighting sequence should then start again. Now release the switch – the display should now show a “1” and the unit will be placed in the settings mode. To exit from this mode, simply switch off and re-apply power without pressing the Up switch. If any of the LEDs fails to light, check its orientation and the soldering. Check also for broken tracks or shorts between pads and tracks. Alternatively, the LED itself may be faulty. Operating The Tacho From 24V DC Want to operate the LED Tachometer and DC Relay Switch from 24V DC? Here’s how to do it: Tachometer • • • Change the 220W resistor feeding zener diode ZD1 to 1kW 1W Increase the voltage rating of the 100mF 16V capacitor at the input of regulator REG1 to 35V Increase the voltage rating of the 470mF 25V low-ESR capacitor following D1 to 35V DC Relay Switch • • • Use a 24V relay instead of a 12V relay – eg, the Altronics S 4208A 24V 30A relay (Jaycar do not have a 24V version). Increase the voltage rating of all capacitors to 35V. Change the 2.2kW resistor in series with LED1 to 4.7kW 0.25W. Dimming response The next step is to adjust the dimming response but first adjust VR1 so that the display is reasonably bright. You can do this using just the “0” display on the righthand digit to judge the brightness or you can use the preceding display test mode to light all the display segments. There are two sets of dimming controls and these allow you to balance the segment brightness on the 7-digit displays. This is necessary because the top and bottom segments of each display are driven by different driver ICs. Begin by adjusting VR2 and VR3 so that the top segments have the same brightness as the bottom segments. In practice, you should not need to vary these much from the previously set half-way position. Do not turn these trimpots fully anticlockwise, otherwise the dimming effect will be lost. Trimpot VR6 sets the dimming threshold – ie, the ambient light level where dimming begins. You can simulate this by placing your finger over the LDR. It’s just a matter of turning VR6 so that the displays begin to dim as the LDR is shadowed. That done, cover the LDR completely and adjust VR4 & VR5 to set the minimum display brightness. Changing the settings As mentioned, the various settings for the tachometer are changed using a special mode of operation (ie, the “settings” mode). As described above, this mode is invoked by holding down the Up switch and simultaneously applying power to the unit (if this switch siliconchip.com.au is not pressed, the tacho­meter operates in “normal” mode). Initially, the unit will go through the display test cycle just described and this is repeated for as long as the Up switch is pressed. Releasing the Up switch then causes the display to show a “1” and invokes the settings mode. The Green Mode LED will also be lit and this indicates that the display is showing the current mode selection (the default is mode 1). You can now change the mode by using the Up or Down switches to select from mode 1 through to mode 13. For each mode, you can force the display to show its current setting by pressing the Toggle switch. During this time, the Red settings LED will light and the Mode LED will be off. The settings are changed by using the Up and Down switches Basically, you have to step through and set each mode in turn. These modes and their options are as follows: Mode 1 – No. Of Cylinders: enter in the exact number of cylinders for a 4-stroke engine (1-12 cylinders). In operation, each cylinder in a 4-stroke engine fires once every two-engine revolutions. This means that a 4-cylinder 4-stroke engine delivers two pulses per revolution to the tachometer, while 6-cylinder and 8-cylinder engines respectively deliver three and four pulses per revolution. A selection of “11” (or “7”) should be made for a 2-cylinder asymmetrical 4-stroke motorcycle engine, where the firing spacings between each cylinder are uneven. This gives a steadier RPM reading compared to using the 2-cylinder option. Similarly, use a “9” setting for an asymmetrically fired 3-cylinder 4-stroke engine. Two stroke engines are also catered for. For these, simply use a cylinder number that’s double the actual number of cylinders. For example, select “2” for a 1-cylinder 2-stroke, 4 for a 2-cylinder 2-stroke, etc. Mode 2 – Red LEDs: this setting refers to the number of red LEDs used for the red line. During construction, you may choose how many red LEDs to use and these are placed at the clockwise end of the bargraph display. The number of LEDs is nominally set at “5”, however any number from 0-10 can be accommodated. Mode 3 – Red Line: this mode is used to set the maximum (or red-line) RPM recommended for your engine. The default setting is 9000 RPM but you can alter this in 100 RPM steps from 0 RPM to above 30,000 RPM. Note that this display is shown in a x1000 RPM format. So 9000 RPM will be shown as 9.00 and 10,000 RPM will be displayed as 10.00. The tachometer will light the first of the red LEDs at the red-line RPM. Mode 4 – RPM/LED: this mode shows the RPM increment for each LED in the bargraph. It is automatically recalculated when ever the number of red-line LEDs is changed (see mode 2) and when the red line RPM is changed (see mode 3). The calculation subtracts the num­ ber of red LEDs from the total of 32 November 2006  81 Table 1: Tachometer Settings Mode Possible Settings Notes 1. Cylinder Number From 1-12 Select exact number for a 4-stroke engine or use twice the cylinder number for a 2-stroke engine. Select 11 (or 7) for an asymmetrical 2-cylinder 4-stroke engine, 9 for an asymmetrical 3-cylinder 4-stroke and 6 for a 3-cylinder 2-stroke. 2. No. Of Red LEDs From 0-10 Allows changes to red-line bargraph display length. 3. Red-Line RPM From 0 to above 30,000 RPM Sets red-line RPM at first red LED. 4. RPM/LED Automatically changed No manual adjustment. Automatically adjusted with changes to Modes 2 and 3. 5. Shift Light RPM From 0 to above 30,000 RPM If not required, set RPM well above red-line RPM. 6. Limiter RPM From 0 to above 30,000 RPM Limiter output changes at limit RPM (see mode 12). 7. Hysteresis 0-255 RPM Prevents LEDs flickering on and off at threshold. Set at less than the RPM/LED value from mode 4. 8. Display Update 0-510ms in 2ms steps Sets digital display updates to a comfortable rate. 9. Display Format 0, 1, 2 1: 9999 RPM, 2: Decimal shift from 9.999 to 10.00, 3: 9.99 to 10.00. 10. Fixed Digits 0, 1, 10 Use 0 for 1 RPM resolution; 1 to fix units digit at 0 (10 RPM resolution); 10 to fix units and tens digits at 0 (100 RPM resolution). 11. Dot or Bar 0 or 1 Use 0 for dot bargraph display, 1 for continuous bargraph display. 12. Limiter Sense 0 or 1 Use 0 to set limit output normally low (0V). Use 1 to set limit output normally high (ie, +5V). 13. Limiter On Period 0-510ms in 2ms steps Sets the minimum time that the limiter output is active. LEDs used in the bargraph and divides this number into the red-line RPM. This then sets the calibration of the tachometer so that the first red LED lights at the correct red-line RPM. As a result, the number of red LEDs determines the total RPM range of the tachometer. This “RPM per LED” value is set automatically and cannot be changed manually. Mode 5 – Shift Light: this mode allows the shift-light RPM to be set. It can be altered in 100 RPM steps from the default value of 8000 RPM, over the range from zero to above 30,000 RPM. The setting is in a x1000 RPM format; eg, 8000 RPM is displayed as 8.00. Mode 6 – Limiter RPM: this mode sets the limiter RPM. In operation, the limiter output changes when the measured RPM goes above this setting and the output level depends on the sense setting (see mode 12). 82  Silicon Chip This setting can be altered in 100 RPM steps from the default of 9900 RPM over a range from zero to above 30,000 RPM. Once again, the display is in a x1000 RPM format; eg, 10,000 RPM will be displayed as 10.00. Mode 7 – Hysteresis: this setting controls the way the LEDs light in the bargraph. As the RPM increases, successively higher LEDs will light up but at the threshold RPM where a LED just lights, there will tend to be some flicker as engine RPM varies slightly (ie, the LED rapidly switches on and off). To prevent this, you can add hysteresis. The hysteresis does not affect the RPM at which each LED will light with rising RPM but it prevents the last lit LED from extinguishing unless the RPM drops by the hysteresis RPM setting. The default hysteresis setting is 50 RPM and this can be altered in 1 RPM steps from 0-255 RPM. Note that the hysteresis value must be less than the RPM/LED value (see mode 4). Mode 8 – Digital Display Update Period: the LED bargraph is updated every 1ms but this is much too fast for the digital display to be read if there are any RPM changes. As a result, the digital display update is slowed down to a more comfortable rate. Typically, a 200ms update period (or five changes per second) is suitable. It can be altered from the default setting of 250ms in steps of 2 from 0-510ms. Mode 9 – Display Format: this adjustment is mainly to cater for engines that rev above 10,000 RPM. The initial setting of “0” sets the display to show RPM from 0-9999 RPM. Above this figure, the display shows a “0” for 10,000 RPM, “1000” for 11,000 RPM etc. Use this setting for engines that do not rev above 10,000 or which only occasionsiliconchip.com.au Fig.8: this diagram shows how to make the bracket and rear panel for the display housing, while the cross-section diagram at left shows how the display assembly goes together. ally rev to this RPM level. For engines that do rev above 10,000 RPM, a “1” or “2” setting will be best. The “1” setting shows the RPM with a shifting decimal point. Below 10,000 RPM the display will show, for example, 9.999 RPM (ie, 9999 RPM), while at 10,000 RPM and above the display decimal point will shift to the right and show the RPM using two digits for the 1000’s value. For example, at 10,000 RPM the display will show 10.00. siliconchip.com.au This is the rear panel (inside view) prior to mounting the PC board. Note the three nuts soldered around the periphery. November 2006  83 The PVC tubing is fitted with a neutral-tint filter and is secured to the PC board and rear panel assembly using three Nylon screws. A black display mask made from film ensures that only the LEDs are visible. If you don’t want the shifting decimal point, select “2”. This will fix the decimal point for two 1000’s digits so, for example, 9999 RPM will be displayed as 9.99, while 10,000 RPM will be displayed as 10.00. Note that for a “2” setting, resolution is reduced to 10 RPM (ie, there’s no units digit). Similarly, for a “1” setting, the resolution is reduced to 10 RPM for RPM values above 9999. Mode 10 – Resolution: in some cases, displaying the RPM to 1 RPM resolution will only be a distraction since the engine may never be stable enough to keep this digit steady – even at a constant throttle. In this case, you can select a “1” for this mode so that the far righthand digit always shows a zero (ie, the resolution is reduced to 10 RPM). Note that this won’t change the display for a “2” setting in Mode 8, because the units digit is not shown. Alternatively, selecting “10” in this mode sets both the units and tens digits to 0. The resolution for the digital display will then be 100 RPM. Mode 11 – Dot or Bargraph: you use this mode to select whether the LED bargraph operates in dot mode (ie, one 84  Silicon Chip You will have to drill and cut suitable holes in the rear panel to accept the power supply and input signal wiring and the IDC cable header. LED lit at any time) or as a continuous bargraph. Select a “0” for dot mode or a “1” for continuous bargraph mode. Mode 12 – Limiter Sense: this mode selects the output sense of the limiter. If “0” is set, the limiter output is normally at 0V and goes to +5V when the RPM rises above the limit setting. Conversely, if “1” is set, the limiter output is normally at +5V and goes to 0V when the limit setting (set in Mode 6) is reached. siliconchip.com.au Connecting A Rev Limiter To The LED Tachometer The limiter output from the tacho­ meter can optionally be used to drive a separate circuit that limits the maximum engine RPM. You can either use an ignition control circuit to do this or a fuel control circuit. Let’s take a closer look at both these options. (1) Ignition Control Limiting An ignition limiter control was published in SILICON CHIP for April 1999. Called a “Rev Limiter”, it’s suitable for use with cars that have a single ignition coil. When the rev limit is reached, the tachometer’s limit output activates the engine limiter, which then acts to reduce the number of sparks per revolution. Note that you don’t have to use the whole circuit from the Rev Limiter. Instead, you only have to use the Ignition Switcher circuit that was assembled on the separate PC board. This Ignition Switcher uses a single 555 timer IC and several transistors to drive a high-voltage Darlington output transistor. When the rev limit is reached, this transistor shunts out the main switching transistor in the car’s ignition system for about 50% of time, thus reducing the engine power and thereby limiting the engine RPM to the red-line. The two circuits are easy to marry – all you have to do is connect the limit output from the LED Tachometer directly to the terminal marked “From Rev Limit Controller” on the Ignition Switcher. A suitable value for C1 must be chosen for the Ignition Switcher from the table published in the April 1999 issue. This sets the requisite Mode 13 – Limiter On Period: this sets the minimum period that the limiter output is active in order to reduce engine RPM to a point below the limit setting. We suggest experimenting with the on periods at a low RPM limit setting and then altering the RPM limit (in Mode 6) to its final value afterwards. OK, that completes the setting up siliconchip.com.au Fig.9: here’s how to wire the tachometer to the DC Relay Switch board to provide fuel-cut limiting of engine RPM. number of sparks that are blocked out during the limiting action. Note that if the LED Tachometer derives its input signal from the coil, it will sense that the RPM has dropped as soon as the coil is prevented from “sparking” via the limiter action. This means that the limit action may not be as smooth as it would be if the tachometer signal were derived from a different source, such as the tacho­ meter output from the ECU. The limit output from the tachometer will remain low to disable the spark for the period that you select. A value of 300ms should provide sufficient time for the limit action to take place. Note that you must set the tachometer’s limiter sense to a “1”, so that the limiter output is normally at 5V and goes to 0V at the limit point. (2) Fuel Cut-Out Limiting A suitable fuel cut-out circuit is published elsewhere in this issue of SILICON CHIP. It’s called a “DC Relay Switch” and it can be used with the procedure. Now let’s complete the construction Tachometer housing If you have an old car, you may be able to install the display board within the existing instrument cluster. Depending on the car, it could either be fitted into a blank space or used tachometer’s limit output to switch off the supply to the fuel injectors. Note that it is suitable only for cars with injectors that are electrically driven (as used in most cars). The tacho’s limiter output drives the relay board as shown in Fig.9. When the red-line limit is reached, the normally closed (NC) relay contacts open and interrupt the positive supply rail to the fuel injectors. The unit is easy to install – just break the +12V supply lead to the injectors and connect the supply side to the relay’s COM (common) terminal. The NC (normally closed) contact is then connected to the injectors. Note that you must set the tacho­meter’s limiter sense to “0” (in Mode 12), so that the limiter output is normally at 0V but goes to +5V at the limit point. You may need to experiment with the limiter on period (set up in Mode 13) for best results. Start with a period of 100ms and decrease or increase this value until you are happy with the limiter action. to replace an unused instrument (eg, a clock). Alternatively, the display board can be built into a small cylindrical housing (see photos). This can be mounted inside the car by attaching it to the windscreen using a suction cap, or it can be fastened to the dashboard via a custom mounting bracket. November 2006  85 Fig.10: the LED Tachometer can derive its input signal from a variety of trigger sources, as shown here. In most modern cars, you will be able to use the tachometer output signal from the engine control unit (ECU). A suitable housing can be made using a 90mm-diameter PVC pipe cut to a length of 21mm. In addition, you will need a 90mm-diameter galvanisedsteel plate for the rear panel and this should be cut and drilled as shown in Fig.8. Three M3 nuts are then soldered around the circumference of this disc in the locations shown. Having done that, carefully mark out and drill three 3mm-diameter countersink in the PVC tube, to exactly line up with these nuts. These holes must also be positioned 5mm in from the rear edge of the tube and should all be countersunk using a slightly oversize drill. Be sure to accurately position these holes around the circumference of the PVC tube, so that they line up with the nuts on the rear plate. The IDC cable passes through a slot in the edge of the plate. This is made by making two cuts and then folding the edge over to as shown in one of the photos. That done, fit four M3 x 6mm-long tapped Nylon spacers to the four inner 86  Silicon Chip holes marked “X” on Fig.8 and secure them using M3 x 12mm Nylon screws. The PC board can then be mounted on these spacers and secured using Nylon nuts. The next job is to make up the aluminium bracket shown in Fig.8. This bracket is attached to the rear plate using M3 Nylon screws, nuts and washers and is fitted with a suction cap to secure the display to the windscreen. You will have to bend the bracket by 20-30° before attaching it to the end plate, to compensate for the rake of the windscreen. Note that it may also be necessary to fit a Nylon washer between the bracket and the rear panel at each mounting point, so that the bracket clears the rear lip of the PVC tube. Alternatively, you can fashion a suitable bracket to attach the display to the dashboard. All that remains now is the final assembly. The cross-sectional diagram in Fig.8 shows how it all goes together. As with the rear plate, the neutraltint front display filter is also 90mm in diameter and should be a tight fit into the PVC tube, so that it stays in place. Apply a couple of small blobs of silicone sealant to the inside rim to secure it in place if it’s a loose fit. If necessary, a black display mask (made from film) can be used to blank out all but the LED displays, so that the PC board and other components cannot be seen through the filter. This will most likely be included in any kits supplied by retailers but if not, you can download the artwork file from the SILICON CHIP website and print it out on clear film. Finally, the PC board and plate assembly can be pushed into the PVC tube and secured using three M3 x 12mm countersink Nylon screws. Installation The first job here is to mount the control box in a suitable location. This needs to go somewhere under the dashboard in a car or inside the side panels of a motorcycle (use silicone sealant to waterproof the cases). Power for the unit can be derived siliconchip.com.au Want cheap, really bright LEDs? We have the best value, brightest LEDs available in Australia! Check these out: Luxeon 1, 3 and 5 watt All colours available, with or without attached optics, as low as $10 each Low-cost 1 watt Like the Luxeons, but much lower cost. •Red, amber, green, blue and white: Just $6 each! Lumileds Superflux These are 7.6mm square and can be driven at up to 50mA continuously. •Red and amber: $2 each •Blue, green and cyan: $3 each Asian Superflux Same as above, but much lower cost. •Red and amber: Just 50 cents each! •Blue, green, aqua and white: $1 each. The IDC cable emerges from the display unit via a 15mmwide slot in the rear panel. At top right is a close-up view of the bracket and suction-cup assembly which allows the unit to be easily attached to a car’s windscreen. from an ignition-switched +12V supply, along with an earth (ie, chassis) connection. In most cars, you will be able to make the +12V connection at the fusebox. Connect to the fused side of the switched +12V supply and use automotive cable and crimp connectors to make the connections. Depending on the car, the input signal for the tachometer can be obtained from the switched (negative) side of the ignition coil primary, from a reluctor or from a tachometer signal provided by the engine control unit (ECU). It’s also possible to use the signals from a Hall effect trigger and from optical triggers. Fig.10 shows all the options. In most modern cars, you can use the ECU’s tachometer signal (C), in which case the link on the control board should be fitted to the LK2 position (ie, to select a low-level input). The link should also go in the LK2 position if you are deriving the signal siliconchip.com.au from a Hall effect sensor (E) or from an optical pick-up (F & G). Alternatively, fit the link in the LK1 (high-level signal) position selection if the signal is derived from the switched side of the ignition coil (A or B). This selection should also be suitable for most reluctors (D). Note that you will need to experiment to determine which lead to use for a reluctor. A reluctor has two leads and only one will have a signal that’s suitable for driving the tachometer. If the tachometer only operates at higher revs and stays at 0 RPM at lower revs, then the reluctor signal level may not be high enough for reliable triggering. In this case, change the link to the LK2 position. Note also that if the tachometer’s reading is erratic when connected to an ignition coil, try adding the second 47nF capacitor. In stubborn cases, this 47nF capacitor may need to be SC increased to 100nF. Go to www.ata.org.au or call us on (03)9419 2440. Serial-to-TCP/IP Converters from TRUSYS Trusys BF-430 & BF-450 universal serial device servers allow your industrial serial devices – such as PLCs, flow meters, gas meters, CNC machines and biometric identification card readers – to be monitored from your network. They support web management & firmware upgrade, while PPPoE & DDNS protocol allows Internet connection without static IP. Event alarm trigger is supported using e-mail & SMS (Short Message Service) to do real-time management for your system. Applications: ] Factory automation ] Hospital automation ] PLC instrument control ] Access control and security ] Time recording system For more information, call, fax, email or visit our website! TRUSYS 95 McCanns Rd Mt Duneed Vic 3216 Tel: 0428 282 222 Fax: 03 5264 1275 Email: sales<at>trusys.com.au www.trusys.com.au November 2006  87 PICAXE Net Server – Pt.3 By CLIVE SEAGER Con t r o l y ou r n ex t el ec t r on i c s p r ojec t f r om v i r t u a l l y a n y w h er e on t h e p l a n e t ! Over the last couple of months, we described how to built a demo board for the PICAXE Net Server (PNS) and then configured a home network to make it accessible over the Internet. This month, we look at building the first of two Internet-enabled demonstration projects. T HE PICAXE NET SERVER is an extremely versatile device. In theory, any application suited to electronic control could be adapted for use with the PNS, suggesting a huge range of applications. On the home front, the PNS might be used to add remote monitoring and control capabilities to a security system, control an airconditioning unit, or feed the pets, for example. 88  Silicon Chip Each new application for the PNS starts with some project design decisions. The first decision is whether you just need simple “on-off” control of output devices or you need to control an automated process. On-off control, as in the case of a pet feeder, would be direct control of a device over the Internet (eg, a relay to activate a motor to open the cat-food tray). To control the output devices (or monitor input values), you would need to build a simple interface circuit that connects directly to the input/output (I/O) pins on the PNS. An example of an automated process would be one used to control the environment in a greenhouse. In this application, temperature, light and humidity levels must be monitored continuously and heaters, fans, lights and sprinklers activated when necessary. The nature of this application demands a dedicated control system, perhaps based on a PICAXE micro. However, the PNS could still be used to monitor and remotely override the controller’s parameters (eg, adjust the temperature threshold). Depending on system’s complexity, the PNS might need to share data (such as temperature and humidity readings) with the greenhouse controller. As we’ll see later, this can be achieved siliconchip.com.au by memory sharing. Notice that in the pet feeder example, the PNS is central to the entire design, whereas in the greenhouse example, it is just one element of an overall system. Let’s study these two interfacing methods as they apply to two simple project examples, including how to generate basic web pages for the PNS to match the hardware setup. First, let’s look at the simpler interfacing method, where the PNS directly controls a motor in a cat feeder application. While you might not want to build your own cat feeder, this simple example clearly demonstrates how to use on-off control and requires only a few additional components. Remote cat feeder A basic feeder might consist of a container with a sliding lid, which is connected to a motor via a lead screw arrangement. When the lid is in position, the pet has no access to the food but when the motor is activated, the lid slides backwards (or rotates) to expose the contents. By placing a microswitch in an appropriate location, it would also be possible to verify that the lid has opened and the animal given access to the food. Jaycar Electronics stock a ready-made automatic feeder (Cat. GH-1190) with a rotating lid – perhaps it could be adapted for remote control! The circuit in Fig.1 shows how output 2 (P2) of the PNS I/O port can be used to drive the motor via a transistor and relay, while the microswitch and a 10kW pull-down resistor are connected to input 3 (P3). We’ve not produced a PC board for this simple design and it could easily be built on a prototyping board if desired. For demonstration purposes, you could also use the demo board from last month to simulate the feeder system. The green LED on the board represents the motor, while the pushbutton switch represents the microswitch. PNS web pages Having built the circuit, we’re ready to create an html web page for the PNS to serve. Fig.2 shows all that’s required: two “buttons” to start and stop the motor and a “LED” to indicate whether the switch is on or off. We’ve kept the page design (and therefore the underlying code) simple, so as siliconchip.com.au Fig.1: this simple circuit enables the PNS to control a motor-driven cat feeder device. Output 2 (P2) of the PNS I/O port is used to drive a transistor (Q1), which in turn actuates a relay to power the motor. The status of the food tray door is detected by a micro-switch, which is wired to the PNS on input 3 (P3). Variations of this circuit could be used in other applications that require basic on/off control. Fig.2: this basic web page enables us to switch the feeder motor on and off, as well as view the status of the microswitch. not to intimidate those new to html programming! This design is actually two separate sections of code which are jointed together in a frame to form one complete web page. Let’s examine the code for the left side of the frame first – see Listing 1: catout.cgi. It uses html forms to display two buttons and perform certain actions, depending on which button is clicked. In more detail, the name= property in the line <input type=hidden name=01 value=2> gives the first form its action, namely to process command “01”. Put simply, this command means “switch an output on”. The output to be switched is determined by the value= property, in this case output 2. November 2006  89 A host of other name= commands are supported by the PNS, facilitating tasks such as speaking a phase using the optional speech synthesiser or updating the message on the LCD screen. You’ll find a comprehensive command summary on page 35 of the PNS manual. Dynamic variables The code for the right half of the page (Listing 2: catin. cgi) is used to display the logic state of input 3, which is connected to the microswitch. The state of this input is retrieved and displayed via a process known as “dynamic variable substitution”. Dynamic variables are numbered from 00-99 and begin with a question mark. Variable “67” in our code equates to input 3, so “?67” will be automatically replaced with the current value of input 3 (“0” or a “1”) every time the PNS serves the web page. This means that the line will appear in your web browser as either “The value of switch 3 is 0” or “The value of switch 3 is 1”. Check out the “Dynamic HTML Generation” section of the PNS manual to find out what the other 99 variables represent! Also of note here is the line <meta http-equiv=”refresh” content=”3”>. This forces your web browser to automatically refresh the web page every three seconds, so you’ll know when the switch is pressed! Fig.3: before connecting new hardware to the PNS, it’s imperative that the I/O configuration is set correctly – otherwise, the PNS could be damaged. Here are the settings for the cat feeder. Note that only bit 2 has been changed from the original defaults. Displaying a LED graphic We’ve also added a “LED” graphic to the page. A green LED (LED0.gif) is displayed when the switch is open and a red LED (LED1.gif) when it’s closed. This is achieved with the <img src=LED?67.gif> line in the code. Again using dynamic variables, this line automatically expands to <img src=LED0.gif> when input 3 is low and <img src=LED1.gif> when input 3 is high – a simple trick for improving the visual appeal of your PNS web pages! Putting it together Fig.4: all of the files for the custom web page(s) must reside in a single folder, where the “Website” wizard will compress them prior to download to the PNS. Don’t be tempted to store other files in this folder, as they will consume unnecessary space in EEPROM. The next line generates the button for this action: <input type=submit value=”Switch motor off”>. The second html form operates similarly but uses name=00 and value=2 properties instead. Deciphered, this means “switch output 2 off”. 90  Silicon Chip All that now remains is to arrange our two sections of code so that they’ll be displayed side-by-side in a browser as one page. This is performed by a third section of code (Listing 3 – index.htm), which uses frames to achieve the task. Note that this code must reside in a file named index.htm, so named because it is the default website page. The frame border can be a useful visual aid when developing web pages but for a more professional look, you may wish to change the border value to 0 so that it is not displayed. So why use frames and two separate sections of code in the first place? Simply because we only want the input (switch) variable to be refreshed every three seconds – not the buttons! Configuring the PNS With the web page built, the next step is to configure the PNS so that the default input/output configuration suits the cat feeder hardware. To do this, run the Programming Editor and select “Setup” from the PICAXE -> Wizards -> PICAXE NetServer menu. From the default options, change input/output 2 to “Out” (3 is already an input – see Fig.3). Also, make sure siliconchip.com.au Listing 1: catout.cgi <html> <head> <title>Cat Feeder Motor</title> </head> <body> <center> Click the button to switch the motor on: <form method=get> <input type=hidden name=01 value=2> <input type=submit value="Switch motor on"> </form> Click the button to switch the motor off: <form method=get> <input type=hidden name=00 value=2> <input type=submit value="Switch motor off"> </form> </body> </html> Listing 2: catin.cgi <html> <meta http-equiv="refresh" content="3"> <head> <title>Cat Feeder Switch</title> </head> <body> <center> The value of switch 3 is ?67 <br> <img src=LED?67.gif> </body> </html> Fig.5: after compression, the new website is downloaded to the PNS via FTP. The “IP Address”, “LogonName” and “Pass­word” fields must all match those shown in the PNS Setup dialog (see Fig. 3). plete, power off and disconnect the serial cable. Downloading the web pages Listing 3: index.htm <html> <head> <title>Cat Feeder </title> </head> <frameset cols="50%,50%" frameborder=1> <frame name="left" src="catout.cgi" marginheight=2 marginwidth=2 frameborder=1> <frame name="right" src="catin.cgi" marginheight=2 marginwidth=2 frameborder=1> </frameset> </html> Listing 4: RC servo driver main: servo 4,75 loop: if input2 = 0 then loop servo 4,225 stop 'closed position 'loop waiting for input 'open position 'stop the program that the IP address settings are correct, as explained in part 1 of this series (see SILICON CHIP, September 2006). Any changes made must be downsiliconchip.com.au loaded to the PNS before they will take effect. Connect the serial cable, power up, click on “Download” and follow the on-screen instructions. Once com- We now need to update the PNS with the newly created web page. First, create a new folder on your computer and make sure that it contains the required files, which are: index. htm, catin.cgi, catout.cgi, led0.gif and led1.gif. These can be downloaded in a single zip file from the SILICON CHIP website. That done, connect the PNS to your network and power up. Again in the Programming Editor, select “Website Image” from the PICAXE -> Wizards -> PICAXE NetServer menu and navigate to the new folder just created (Fig.4). Now click on the “Compress” button to generate the PNS memory (EEPROM) image. Next, click on the “Download via FTP” button and the “FTP Transfer” window appears (Fig.5). Change the IP address to match your PNS and then click the “Connect” button. If the PNS is found, you can then click the November 2006  91 Fig.6: as well as directly driving external devices such as transistors and LEDs, the PNS I/O lines can be used as signals to trigger “smart” devices, such as a PICAXE microcontroller. Again using our cat feeder as an example, a PICAXE08M drives an RC servo to open or close the feeder door when output 2 of the PNS changes state. “Transfer” button to transfer the actual compressed image to the PNS. Moment of truth Now move back to your web browser software and type in the PNS address (in the examples given, this is 192.168.1.10). If all is well, your new web page should look like Fig.2! Verify that by clicking on the buttons, you can switch output 2 on and off, and by operating the switch, 92  Silicon Chip the logic value toggles and the LED graphic alternates between green and red. Remember, though, that the page is refreshed only every three seconds! trigger to initiate servo operation. Fig.6 shows a suitable circuit, while a matching program for the PICAXE-08M appears in Listing 4. Alternative mechanism Coming next month An alternative method of opening the feeder lid would be to use an RC-style servo controlled by a PICAXE-08M chip. In this case, the output from the PNS would be connected to an input of the PICAXE-08M and act as a Congratulations, you have now designed and developed your first PNS project! Next time around, we will build a more complex project that shares data in real-time with a PICAXE SC microcontroller! siliconchip.com.au PRODUCT SHOWCASE DENON’S new DVD-2930 1080p Universal Player: “As good as it gets!” Denon’s latest generation high definition 1080p universal player, the DVD-2930 features 10-bit video processing together with 216MHz, 12-bit D-to-A conversion, producing the highest quality, high definition 1080p images. As a Universal player it supports all current surround sound and music digital formats including DVD Audio and Video, SACD, MP3, WMA, DIVX, and of course will play regular CDs and their variants. A clear reminder that not all DVD players are created equal, the DVD2930 employs the much anticipated, cutting-edge Reon-VX chip from Silicon Optix that is designed to deliver optimum picture quality for content shown by major TV networks and ‘Hollywood’ DVDs. Key features of the new chip include no-compromise HQV True 1080i-1080p de-interlacing, which uses the full four-field processing window for HD video deinterlacing and cadence detection, thus preserving the rich details in HD imagery. In addition, the REON processor includes HQV (Hollywood Quality Video) processing, and together with Denon’s proprietary noise reduction system and advanced scaling technology, the DVD-2930 can make regular DVDs approach the quality of High Definition DVD. This latest Universal player also features a state-of-the-art, high performance 10-bit video scaler that works with HDMI digital video signals. The scaler executes optimum conversion to suit the output of independent HDMI transmitters and can also output PC resolution VGA/XGA/WXGA and SXGA. This is particularly useful 94  Silicon Chip when it addresses PCs and PC-based LCD monitors, as it automatically formats to these display standards. For the best in audio, the DVD-2930 employs Burr Brown 24-bit, 192kHz audio D/A converters, while HDCD decoding extracts the very best out of both HDCD encoded discs and also yields more true to life sound from standard CDs. The DVD-2930’s Discrete Audio/ Video and digital Bass Management circuitry, together with Speaker Configuration Level and Delay Time Controls, allows you to tailor your sound to a wide variety of set-ups including full-size speakers to sub/set systems. The DVD-2930 also boasts Denon LINK 3rd edition, which provides fully balanced output of DD/dts/DVDA/PCM/SACD for digital, one-cable audio hook-up to compatible Denon A/V components. The DVD-2930 offers fast loading disc recognition, automatic switching, picture adjustment controls, an intuitive on-screen menu system, WMA file navigation and a fully functional remote control. Connections include the latest HDMI, Component, S-Video, Composite plus coaxial and optical digital outputs and multi-channel analog audio outputs. The Denon DVD-2930 has a recommended retail price of $1,699 and is covered by a nationwide two-year warranty. It is now available at selected Denon dealers throughout Australia Contact: Audio Products Group (Australia) 67 O’Riordan St, Alexandria NSW 2015 Tel: (02) 9669 3477 Fax: (02) 9578 0140 Website: www.audioproducts.com.au RS Components nominated for Elektra 06 Awards RS Components have been shortlisted for the Elektra 06 European Electronics Industry Awards. An independent panel of judges includes specialists from Afdec, Envirowise, ISLI, NMI, Qinetiq, Roke Manor Research and the University of Manchester. The company has been nominated for: • Distributor of the Year • Online Business Award • Environmental Award RS Components offers over 50,000 electronic, electrical and industrial products ex-stock, with an additional 130,000 on their web site at www.rsaustralia.com Established in Australia in 1976 under the name of ‘Radiospares’ and then later renamed RS Components in 1990 the company has enjoyed strong growth through the years and now has over 40,000 customers across the country. Part of a global business, RS has operating companies in 25 countries around the world including UK, France, Italy, Germany, Spain, China, Japan, Singapore, Hong Kong, USA and New Zealand. Ordering is via phone, fax or web and guaranteed next day delivery is free for orders over $100 (exc. GST) to anywhere in Australia. The company also offers free technical help from our team of technical specialists and over 40,000 datasheets can be accessed online. Same day delivery is available from the local RS Trade Counter network, which are based in Perth, Sydney, Brisbane and Melbourne and provide 17,500 of the most popular products from the range. Contact: RS Components 25 Pavesi St, Smithfield NSW 2164 Orderline Phone: 1300 656 636 Orderline Fax: 1300 656 696 Website: www.rsaustralia.com siliconchip.com.au 4-channel Standalone Digital Video Recorder Digital Video Recorders (DVRs) are starting to get a little passe now, having well and truly taken over from the old faithful VCR in hifi shop sales. But if you’re into a lot of simultaneous recording, this 4-channel model from Avcomm is worth another look. As well as operating in standalone mode, it can plug into a standard USB port on your computer, to allow a vast range of image manipulation. In addition, it will also output to a standard monitor via A-V connections so you can also view in “real time”, with a live display resolution of 720 x 576. You can convert the images to bitmap (BMP) or AVI format for further manipulation in PC software. The immediate (and probably intended) role is for security applications, with four simultaneous cameras being accessed – both for recording and for viewing. It comes complete with an 80GB hard disk drive but larger drives can easily be fitted by the end user, if required. The unit will automatically format a new hard disk if it determines that one has been changed. It can be set to record in continuous or manual modes, or scheduled to record at certain times, or start recording on (external) alarm or with motion. Video input is a standard 1V, 75W so it will accept a variety of input sources (even TV tuners!). Driver software, USB cable and AC/ DC adaptor are all supplied. Recommended retail price is $599.00 Contact: Av-Comm PO Box 225, Brookvale NSW 2100 Tel: (02) 9939 4377 Fax: (02) 9939 4376 Website: www.avcomm.com.au Rain Alert gauge monitors tank levels A new, easy and safer way to monitor the level of your rainwater tank from a convenient location inside the house, has been introduced by water solutions company New Water. New Water is an Australian company which sells innovative, customised water solutions in the form of grey water recycling and rainwater harvesting tanks and systems. The Rain Alert gauge suits all vented tanks up to three metres high, providing an easy-to-install wireless method for monitoring tank levels. The transmitter sits on top of the tank, using ultrasonics to gauge the level of fluid in the tank. The receiver, which can be located up to 200m from the tank, is plugged into a power point and a small LCD panel continuously shows how much water is in the tank. If the tank level falls below a predetermined level, the LCD panel will flash a ‘Tank Fill’ picture and when it is almost empty a red warning light will flash to indicate the low tank level. Rain Alert is a safe option to monitoring tank levels as it doesn’t require climbing on top of the tank and reaching in to make measurements. The lithium battery in the transmitter has a life of ten years and the entire device comes with a one year warranty. The cost of a standard unit to fit a tank is $160 and is available direct from New Water. Contact: New Water PO Box 1006, Ringwood, Vic 3134 Tel: (03) 8873 3600 Fax: (03) 9873 2844 Website: www.newwater.com.au siliconchip.com.au Glyn Ltd distributes Jennic Zigbee Glyn Ltd has been appointed Australia and New Zealand distributor of leading UK-based ZigBee wireless solutions provider, Jennic. The Jennic JN5121 is the first in a series of low-power, low-cost IEEE 802.15.4 compliant wireless microcontrollers designed and manufactured by Jennic. Combining an on-chip 32-bit RISC core, a fully compliant 2.4GHz IEEE802.15.4 transceiver, 64kB of ROM and 96kB of RAM. The JN5121 provides a versatile low-cost solution for wireless sensor networking applications. The ROM enables integration of point-to-point and mesh network stack protocols, and the RAM allows support of router and controller functions without the need for additional external memory. It uses hardware MAC and highly secure AES encryption accelerators for low power and minimum processor overhead. Integrated sleep oscillator and power saving facilities are provided, giving low system power consumption. The device also incorporates a wide range of digital and analog peripherals for the user to connect to their application. Jennic also designs and manufactures ZigBee/IEEE 802.15.4 wireless modules. Contact: Glyn Ltd Australia PO Box 7838, Baulkham Hills Business Centre, Baulkham Hills NSW 2153. Tel: (02) 8850 0320 Fax: (02) 8850 0370 Website: www.glyn.com.au TOROIDAL POWER TRANSFORMERS Manufactured in Australia Comprehensive data available Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 November 2006  95 Vintage Radio By RODNEY CHAMPNESS, VK3UG Radio Corporation’s WS108 Transceiver The “portable” radio equipment used by the military at the start of World War 2 was bulky, heavy and inefficient by today’s standards. Here we take a look at Radio Corporation’s WS108 transceiver, as used by the Australian army. B EFORE AND DURING World War II, Radio Corporation made many radio transceivers for use by the military. In fact, we’ve already looked at the advanced WS122 in Vintage Radio for October 2002. The WS122 was intended for fixed, portable and – at a pinch – vehicle mobile use. By contrast, the WS108 in all its various marks was intended as a backpack transceiver (basically, a predecessor to “walkie talkies”), although it was also used for low-power fixed operation. This set is claimed to be the first backpack set designed and built in Australia. A Morse code only variant, designated the 208, was used by Australian commandos and coast watchers in the Pacific area during World War II. Bulky equipment The WS108 transceiver – the first backpack set designed and built in Australia. 96  Silicon Chip Most of the radio equipment used at the start of WWII was bulky, heavy and inefficient, with high current consumption. Designing equipment for mains operation is relatively easy, as it’s not necessary to be concerned about the total electrical power requirements. However, it’s a different story when it comes to designing equipment for battery operation. It soon became obvious that there was an urgent need for a fully-portable voice transceiver for use by troops within an infantry battalion or similar unit. This had to be small enough for a soldier to carry on his back and he had to be able to operate the set on the move. This was probably not a favoured task, as the high frequency (HF) whip/rod type antenna connected to such sets would be sticking up above the horizon and acting as a beacon for the enemy’s sharp shooters! The British military had the No.18 set and this became the blueprint for the “Australianised” backpack set. Radio Corporation (Astor) designed and built this version, the 108. The 108 Mk.1 (1941) only tuned the range siliconchip.com.au from 8.5-8.9MHz, while the improved 108 Mk.2 (1941) tuned from 6-9MHz. The final production model, the Mk.3 (1943/4) tuned from 2.5-3.5MHz and had provision for Morse code transmission as well. Another variant was the 208 (1941/2) which was purely a Morse code (CW) transceiver. There was also a Mk.4 version developed but the war ended before it was put into full-scale production. Army cadets got to play with the few that were made, according to Rod Allen, VK4CJ. The 108s were subsequently superseded by the vastly superior 128 transceiver, which was approved for production in 1945. In addition, towards the end of the war, the American SCR536/BC611 walkie-talkie came into use and this was so superior to the 108 that the Mk.4 would have been obsolete even before it was built. The 108 Mk.2 The 108 Mk.2 has a conventional superhet receiver with an RF stage, converter, two IF amplifiers, a detector/AGC stage and two audio stages – see Fig.1. A well-designed set with that number of battery valves is sure to be a good performer. It was designed to operate with a very small whip antenna 1-2 metres long and this is connected to the top of the antenna coil via blocking capacitor C1A. The tuned circuit for the coupling between the RF amplifier and the converter is in the plate circuit of the radio frequency (RF) amplifier (V1A) rather than in the grid, as is the more usual practice. The oscillator section of V2A (1A7­ GT) is similar to other pentagrid mixers. The intermediate frequency (IF) is at 1600kHz and is selected from the various mixing products at V2A’s plate. By contrast, the IF of the Mk.1 was 455kHz and breakthrough on the image frequency (double spotting), which is only 910kHz away from the desired signal, would have been a real problem. In addition, the selectivity of the antenna circuit and the broad-banded RF tuned circuit would have been inadequate to reject this unwanted frequency. By using an IF of 1600kHz for the Mk.2, break-through of unwanted stations 3200kHz away would be rare due to the selectivity of the RF and antenna stages, which would strongly reject signals at the image frequency. siliconchip.com.au This view shows the top of the chassis after restoration. Note the rewired “netting” switch on the front panel. Following the mixer, the signal is passed through double-tuned IF transformer T1A, valve V1B and doubletuned IF transformer T1B to V1C, and then via IF transformer T2A to the diode detector in V3A (1D8GT). The signal is detected in V3A (1D8GT) and AGC voltage is fed back to V1A and V1B. V2A and V1C do not have AGC applied to them. Following the detector, the audio is fed via volume control (R8A) to the grid of the 1D8GT’s triode section. The resulting signal on the plate is then applied to the grid of the pentode in the 1D8GT, after which it is extracted from the pentode’s plate circuit and fed to the headphones via T3A. The way that the 1D8GT has been drawn in the circuit diagram is unusual to say the least (and confusing as well). Reference to a valve data book makes it easier to follow this part of the circuit. Transmitter circuit The transmitter circuit is fairly simple. The carrier frequency is derived using a variable frequency oscillator (VFO) based on V4A (1Q5GT). This VFO covers from 6-9MHz and this frequency range is spanned by two complete turns of the frequencycontrol knob. As a result, it’s not easy to accurately set the transmitter frequency with such a direct tuning mechanism. An alternative method of selecting a frequency is to select one of four preset frequencies using switch S3A. However, in the handbook, it is suggested that these preset frequencies should not be set in the field in the absence of technical personnel (more on this later). The output from V4A is coupled to the grid of V4B, which functions as an RF (radio frequency) power amplifier. It’s output is fed to the antenna via a tuned circuit consisting of L8A, C11D and C16A. Because the antenna length is only a fraction of the signal wavelength, it is connected to the unearthed end of tuning capacitor C16A. Capacitor C11D passes the RF and blocks the 90V HT from being applied to the antenna. In order to put voice onto the carrier, November 2006  97 winding of T3A and this modulates the 90V supply to the PA (V4b). This causes the amount of voltage applied to the PA stage to vary, which means that the transmitter’s output varies as well. Netting It was usual for transceivers such as this to transmit and receive on the same frequency and this was achieved using a facility called “netting”. This involved providing a low-level signal from the transmitter that was then picked by the receiver. When the transmitter and receiver frequencies were the same, the receiver would go “quiet”. Alternatively, if the “control” station was transmitting, the local transmitter signal would initially appear as a whistle in the receiver as the VFO was adjusted. In practice, the transmitter frequency control was adjusted until the whistle disappeared – ie, at “zero beat” or zero frequency difference. The local unit and the “control” station would then be on the same (nominal) frequency. In fact all stations in the group would “net” to the “control” station so that they could all talk to one another. The netting switch in the 108 is S2A and this is located just below the common earth line in the circuit diagram. In this set, when netting occurs, the receiver is operated as normal, the VFO is run at reduced voltage and the PA is made inoperative. Only a low-level signal is required, as the transmitter is in the same case as the receiver. Overhauling the receiver These two under-chassis views show the unit before restoration (top) and after restoration (bottom). Most of the work here involved replacing defective capacitors. it is necessary to have a modulator and this is provided by the 1D8GT (V3a). V3a fulfils a dual role as it also functions as the audio output stage for the receiver. On receive, the lower secondary winding of T3A is switched through to the headphones. Converse98  Silicon Chip ly, on transmit, the upper winding on the secondary is switched in series between the 90V supply rail from the batteries and the plate and screen of the power amplifier (PA) valve. In operation, the modulator’s audio output appears across the secondary The first thing I noticed when it came to the restoration was that the netting switch was missing from the top-centre of the control panel. This didn’t augur well for restoring the set to its original condition and I was concerned as to what other modifications might have done to the set. In fact, it’s sometimes necessary to admit defeat if the modifications are too extensive and I sometimes wonder why people do such extensive modifications to sets. One of our local club members has bought sets on eBay and has been caught out this way. Fortunately, in this case, there didn’t appear to be any other drastic modifications, so I decided to go ahead with the restoration. It wasn’t hard siliconchip.com.au Removing the chassis The chassis itself is quite easy to remove from the case, it being necessary to remove just one knurled-head screw on the front of the set. However, it isn’t normally possible to operate siliconchip.com.au Fig.1: the WS108 uses a conventional superhet receiver with an RF stage, converter, two IF amplifiers, a detector/AGC stage and two audio stages. By contrast, the transmitter is fairly simple and uses a variable frequency oscillator (VFO) based on V4A (1Q5GT) to derive the carrier frequency. V3a functions as the modulator (and as the audio output stage for the receiver section), while V4b functions as an RF power amplifier. to find and fit a 4-pole 2-way switch and matching knob. The only problem here was that I didn’t have a springloaded switch like the original, so I would have to manually switch back to receive from “net”. However, that was a minor problem compared with finding out what the previous owner had done with the eight wires that had gone to the switch. I couldn’t see where they had come from, as the wiring in the set is rather dark and it’s hard to find your way around. Eventually, I was able to locate the transmitter and receiver filaments so I was able to initially wire the extreme left switch contacts into circuit. Figuring out the remaining wiring to the three switch sections was a much more time-consuming task and it took me two full days to complete this job. About this time, I also discovered that the 10mA meter in the plate circuit of the PA valve had gone open circuit. I dismantled the meter but no obvious breaks in the wiring could be found. Fortunately, I had a meter from another Radio Corporation transceiver and it had the right sensitivity and the correct mounting hardware. Unfortunately, its appearance and meter scale are different to the original but it will do the job until an exact replacement comes along. I was going to repaint the case but changed my mind when I discovered that suitable matte-finish paint would set me back $25. As a result, I thoroughly cleaned the case with household kerosene on a rag and while it looks better that it did, gouge marks and rust are still quite evident. Of course, it’s always a moot point as to whether an item being restored should look exactly as it did when it came out of the factory or simply restored to working order but left with its original finish. Unfortunately, I have only a few of the bits and pieces that make up the complete station. For example, I don’t have the antenna or the control cables and had to “make do” with a microphone and set of headphones from another military set. November 2006  99 All accessories, including the headphones, microphone, a 3-position remote switch control and a small telescopic antenna are stored in the lid of the case (the black and white photo at left is from the manual). Most of these items are missing from the author’s set. the set out of the case as the batteries and the headphone and microphone leads are automatically connected via a Jones plug and socket arrangement attached to the back of the case and the rear of the chassis. As a result, I obtained a 6-pin Jones socket and wired it so that I could supply 1.4V and 90V to the set and connect the headphones and microphone. As with all old sets, I checked the AGC bypass and audio coupling capacitors for leakage. As usual, the AGC bypasses were too leaky to leave in circuit and these were replaced with .047mF 50V ceramic disc capacitors. The audio coupler (C5B) is a mica capacitor, so it was left in circuit. However, all the other paper capacitors were excessively leaky and were replaced with 160V polyester capacitors. The back bias capacitor C12A, a 25mF 40V electrolytic, was also replaced. Unfortunately, this circuit isn’t the easiest to find your way around, as there are a few errors in it. Two were picked up by the military and the corrections published, while I found another one that had been missed. Receiver tests The 108 was designed to work with two low-impedance headphones so I connected a 15-ohm loudspeaker to the line that comes out to pin 1 on the Jones plug. I then clipped the output lead from my LSG11 signal generator over an insulated antenna lead I had attached to the set, adjusted the 100  Silicon Chip signal generator for full output and tuned the receiver to find the signal. A weak signal was heard, which led me to believe that something must be wrong with the receiver. So what else had the previous owner been up to? The IF alignment was the obvious suspect, even though the adjustment slugs had been well-sealed with beeswax. Initially, I found that I could get only a weak response on 1600kHz (the IF frequency) so I started adjusting the cores and was immediately greeted by increased sensitivity. And once all the five slugs had been adjusted, the performance was quite good. It’s difficult to know what the previous owner was doing when he aligned the set. He was certainly liberal with his use of beeswax! Overhauling the transmitter The transmitter’s RF output circuit is designed to feed a non-resonant short telescopic antenna, which presents a high impedance to the PA’s tuned plate circuit. However, the previous owner had modified the circuit so that a relatively low-impedance antenna could be used, such as a quarter wave end-fed antenna. It’s also much easier to measure RF power into low-impedance resistive loads such as a 50-ohm “dummy” antenna than trying to simulate a highimpedance reactive load, as presented by a short telescopic antenna (a suitable “dummy” load can be made using a 50-ohm non-inductive resistor and this acts like an antenna with a resistive feed impedance of 50 ohms). The transmitter stage uses lots of mica capacitors and none of these required replacement. In fact, the transmitter section was in better condition than the receiver. Next, I applied power to the set and with the receiver turned on, adjusted the transmitter frequency with the “netting” on until the receiver went quiet (this meant that the transmitter was now tuned to the same frequency as the receiver). I then checked the unit out across its entire 6-9MHz tuning range and found that the dial calibrations for both the receiver and transmitter stages were reasonably accurate. Now for some power measurements. This was done by attaching the set to a 50-ohm RF power meter (a “dummy” load with a meter attached to measure power) and then turning the transmitter on. Initially, the power was around 40mW which wasn’t anything to write home about. I then experimented with the coupling and was able to get the transmitter output power up to 120mW. This involved winding three turns of insulated wire over the earthy end of the tuned circuit, which proved more effective than the previous owner’s modification. It was now simply a matter of checking that the unit was working correctly. To do this, I tuned in my siliconchip.com.au amateur radio receiver and found that this had no trouble picking up the signal from the transmitter into the dummy load. I then modulated it with tone using a small audio generator and the transmitted audio sounded quite acceptable. Finally, I tried using a hand-held carbon microphone and once again the transmitted audio was quite satisfactory. In operation, the transmitter and the receiver are remarkably stable once set to a frequency, with little drift in the tuning. However, as mentioned previously, exact “netting” to frequency isn’t an easy task with these sets. One problem alluded to earlier in the article is the problem of adjusting the four preset transmitter channels. The frequency adjustments are set using a screwdriver to vary four airspaced trimming capacitors and just half a turn (180)° changes the preset frequency from 6MHz to 9MHz. As a result, the adjustment is very critical and it’s just as well that the selectivity of the receivers in these sets isn’t as narrow as it would be with 455kHz IF stages, otherwise it would be almost impossible to get them accurately tuned. Photo Gallery: AWA Model 517M (1948) MANUFACTURED BY AWA in 1948, the 517M was a very popular 4-valve mantel receiver housed in a bakelite cabinet. It featured concentric volume control and tuning knobs in the middle of a circular dial and was produced in several colours. The green cabinet shown here is now hard to find. The valve line-up was as follows: 6A8-G frequency changer; 6G8-G reflexed IF amplifier/1st audio amplifier/detector/AVC rectifier; 6V6-GT audio output; and 5Y3-GT rectifier. Photo: Historical Radio Society of Australia, Inc. Summary The 108 is a cumbersome “little” beast, which is not all that easy to use on the move. It remains on frequency remarkably well when operated on the bench but just how well it did when being bumped along on a private’s back is another matter. It’s output power is also quite low at around 120mW, which gives it a range of about 3km as a pack set. By way of comparison, a modern 27MHz CB radio has an output power of 4W on AM – more than 33 times that of the 108. The Mk.1 was probably not much of a success but the Mk.2 would have been reasonably good in the African desert. The Mk.3 would have been even more versatile, as it used lower frequencies which would have been better in the jungles of South East Asia. It was also capable of being used on Morse code and could be operated with a variety of antennas. Finally, although the 108 may have been satisfactory when was first produced, it was obsolete even before the end of WWII. Radio Corporation also produced the 122 which was a much more advanced design for the time. The 108 wasn’t the most remarkable transceiver of its time but it’s still an interesting item to have in a military SC radio collection. WIN ME! Commence a new subscription (or renew an existing one) between now and Christmas and you’ll go in the draw to win a pair of these superb M6 bass-reflex kit speakers, valued at $599 – as featured in this issue – courtesy of theloudspeakerkit.com See page 61 for full details siliconchip.com.au SILICON CHIP www.siliconchip.com.au November 2006  101 Silicon Chip Back Issues 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 1994:90-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; 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: 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. August 1994: High-Power Dimmer For Incandescent Lights; Dual Diversity Tuner For FM Microphones, Pt.1; Nicad Zapper (For Resurrecting Nicad Batteries); Electronic Engine Management, Pt.11. September 1994: Automatic Discharger For Nicad Batteries; MiniVox Voice Operated Relay; AM Radio For Weather Beacons; Dual Diversity Tuner For FM Mics, Pt.2; Electronic Engine Management, Pt.12. October 1994: How Dolby Surround Sound Works; Dual Rail Variable Power Supply; Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Electronic Engine Management, Pt.13. November 1994: Dry Cell Battery Rejuvenator; Novel Alphanumeric Clock; 80-M DSB Amateur Transmitter; 2-Cell Nicad Discharger. December 1994: 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; Dual Channel UHF Remote Control; Stereo Microphone Pre­amp­lifier. February 1995: 2 x 50W Stereo Amplifier Module; Digital Effects Unit For Musicians; 6-Channel LCD Thermometer; Wide Range Electrostatic Loudspeakers, Pt.1; Remote Control System For Models, Pt.2. March 1995: 2 x 50W 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. April 1995: FM Radio Trainer, Pt.1; Balanced Mic Preamp & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. May 1995: 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. 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. 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. August 1995: Fuel Injector Monitor For Cars; Build A Gain Controlled Microphone Preamp; How To Identify IDE Hard Disk Drive Parameters. ORDER FORM September 1995: Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.1; Keypad Combination Lock; Jacob’s Ladder Display. October 1995: 3-Way Loudspeaker System; Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.2; Nicad Fast Charger. November 1995: Mixture Display For Fuel Injected Cars; CB Trans­verter For The 80M Amateur Band, Pt.1; PIR Movement Detector. December 1995: Engine Immobiliser; 5-Band Equaliser; CB Transverter For The 80M Amateur Band, Pt.2; Subwoofer Controller; Knock Sensing In Cars; Index To Volume 8. For Stepper Motor Cards; Understanding Electric Lighting Pt.2; Index To Vol.10. January 1998: 4-Channel 12VDC or 12VAC Lightshow, Pt.1; Command Control For Model Railways, Pt.1; Pan Controller For CCD Cameras. February 1998: Telephone Exchange Simulator For Testing; Command Control For Model Railways, Pt.2; 4-Channel Lightshow, Pt.2. April 1998: Automatic Garage Door Opener, Pt.1; 40V 8A Adjustable Power Supply, Pt.1; PC-Controlled 0-30kHz Sinewave Generator; Understanding Electric Lighting; Pt.6. May 1998: 3-LED Logic Probe; Garage Door Opener, Pt.2; Command Control System, Pt.4; 40V 8A Adjustable Power Supply, Pt.2. June 1998: Troubleshooting Your PC, Pt.2; Universal High Energy Ignition System; The Roadies’ Friend Cable Tester; Universal Stepper Motor Controller; Command Control For Model Railways, Pt.5. May 1996: High Voltage Insulation Tester; Knightrider LED Chaser; Simple Intercom Uses Optical Cable; Cathode Ray Oscilloscopes, Pt.3. July 1998: Troubleshooting Your PC, Pt.3; 15W/Ch Class-A Audio Amplifier, Pt.1; Simple Charger For 6V & 12V SLA Batteries; Auto­ matic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. June 1996: Stereo Simulator (uses delay chip); Rope Light Chaser; Low Ohms Tester For Your DMM; Automatic 10A Battery Charger. August 1998: Troubleshooting Your PC, Pt.4; I/O Card With Data Logging; Beat Triggered Strobe; 15W/Ch Class-A Stereo Amplifier, Pt.2. July 1996: VGA Digital Oscilloscope, Pt.1; Remote Control Extender For VCRs; 2A SLA Battery Charger; 3-Band Parametric Equaliser;. September 1998: Troubleshooting Your PC, Pt.5; A Blocked Air-Filter Alarm; Waa-Waa Pedal For Guitars; Jacob’s Ladder; Gear Change Indicator For Cars; Capacity Indicator For Rechargeable Batteries. August 1996: Introduction to IGBTs; Electronic Starter For Fluores­cent 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; HF Amateur Radio Receiver; Cathode Ray Oscilloscopes, Pt.5. October 1996: Send Video Signals Over Twisted Pair Cable; 600W DC-DC Converter For Car Hifi Systems, Pt.1; IR Stereo Headphone Link, Pt.2; Multi-Channel Radio Control Transmitter, Pt.8. November 1996: 8-Channel Stereo Mixer, Pt.1; Low-Cost Fluorescent Light Inverter; Repairing Domestic Light Dimmers; 600W DC-DC Converter For Car Hifi Systems, Pt.2. December 1996: Active Filter For CW Reception; Fast Clock For Railway Modellers; Laser Pistol & Electronic Target; Build A Sound Level Meter; 8-Channel Stereo Mixer, Pt.2; Index To Vol.9. October 1998: AC Millivoltmeter, Pt.1; PC-Controlled Stress-O-Meter; Versatile Electronic Guitar Limiter; 12V Trickle Charger For Float Conditions; Adding An External Battery Pack To Your Flashgun. November 1998: The Christmas Star; A Turbo Timer For Cars; Build A Poker Machine, Pt.1; FM Transmitter For Musicians; Lab Quality AC Millivoltmeter, Pt.2; Improving AM Radio Reception, Pt.1. December 1998: Engine Immobiliser Mk.2; Thermocouple Adaptor For DMMs; Regulated 12V DC Plugpack; Build A Poker Machine, Pt.2; Improving AM Radio Reception, Pt.2; Mixer Module For F3B Gliders. January 1999: High-Voltage Megohm Tester; A Look At The BASIC Stamp; Bargraph Ammeter For Cars; Keypad Engine Immobiliser. March 1999: Build A Digital Anemometer; DIY PIC Programmer; Build An Audio Compressor; Low-Distortion Audio Signal Generator, Pt.2. January 1997: Control Panel For Multiple Smoke Alarms, Pt.1; Build A Pink Noise Source; Computer Controlled Dual Power Supply, Pt.1; Digi-Temp Thermometer (Monitors Eight Temperatures). 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. February 1997: PC-Con­trolled Moving Message Display; Computer Controlled Dual Power Supply, Pt.2; Alert-A-Phone Loud Sounding Telephone Alarm; Control Panel For Multiple Smoke Alarms, Pt.2. May 1999: The Line Dancer Robot; An X-Y Table With Stepper Motor Control, Pt.1; Three Electric Fence Testers; Carbon Monoxide Alarm. March 1997: 175W PA Amplifier; Signalling & Lighting For Model Railways; 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. June 1997: PC-Controlled Thermometer/Thermostat; TV Pattern Generator, Pt.1; Audio/RF Signal Tracer; High-Current Speed Controller For 12V/24V Motors; Manual Control Circuit For Stepper Motors. July 1997: Infrared Remote Volume Control; A Flexible Interface Card For PCs; Points Controller For Model Railways; Colour TV Pattern Generator, Pt.2; An In-Line Mixer For Radio Control Receivers. 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. July 1999: Build A Dog Silencer; 10µH to 19.99mH Inductance Meter; Audio-Video Transmitter; Programmable Ignition Timing Module For Cars, Pt.2; XYZ Table With Stepper Motor Control, Pt.3. 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. September 1999: 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. October 1999: 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. October 1997: 5-Digit Tachometer; Central Locking For Your Car; PCControlled 6-Channel Voltmeter; 500W Audio Power Amplifier, Pt.3. November 1999: Setting Up An Email Server; Speed Alarm For Cars, Pt.1; LED Christmas Tree; Intercom Station Expander; Foldback Loudspeaker System; Railpower Model Train Controller, Pt.2. November 1997: Heavy Duty 10A 240VAC Motor Speed Controller; Easy-To-Use Cable & Wiring Tester; Build A Musical Doorbell; Replacing Foam Speaker Surrounds; Understanding Electric Lighting Pt.1. December 1999: Solar Panel Regulator; PC Powerhouse (gives +12V, +9V, +6V & +5V rails); Fortune Finder Metal Locator; Speed Alarm For Cars, Pt.2; Railpower Model Train Controller, Pt.3; Index To Vol.12. December 1997: Build A Speed Alarm For Cars; 2-Axis Robot With Gripper; Stepper Motor Driver With Onboard Buffer; Power Supply January 2000: Spring Reverberation Module; An Audio-Video Test Generator; Parallel Port Interface Card; Telephone Off-Hook Indicator. Please send the following back issues:________________________________________ Enclosed is my cheque/money order for $­______or please debit my: o Bankcard o Visa Card o Master Card Card No. Signature ___________________________    Card expiry date_____ /______ Name _____________________________    Phone No (___) ____________ PLEASE PRINT Street _________________________ Suburb/town ____________________ Postcode ________ Email Address _________________________________ 102  Silicon Chip 10% OF SUBSCR F TO IB OR IF Y ERS OU 10 OR M BUY ORE Note: prices include postage & packing Australia ............................... $A9.50 (incl. GST) Overseas (airmail) ..................................... $A13 Detach and mail to: Silicon Chip Publications, PO Box 139, Collaroy, NSW, Australia 2097. Or call (02) 9939 3295 & quote your credit card details; or fax the details to (02) 9939 2648. Email: silicon<at>siliconchip.com.au siliconchip.com.au February 2000: Multi-Sector Sprinkler Controller; A Digital Voltmeter For Your Car; Safety Switch Checker; Sine/Square Wave Oscillator. March 2000: Resurrecting An Old Computer; 100W Amplifier Module, Pt.1; Electronic Wind Vane With 16-LED Display; Glowplug Driver. May 2000: Ultra-LD Stereo Amplifier, Pt.2; LED Dice (With PIC Microcontroller); 50A Motor Speed Controller For Models. June 2000: Automatic Rain Gauge; Parallel Port VHF FM Receiver; Switchmode Power Supply (1.23V to 40V) Pt.1; CD Compressor. July 2000: Moving Message Display; Compact Fluorescent Lamp Driver; Musicians’ Lead Tester; Switchmode Power Supply, Pt.2. August 2000: Theremin; Spinner (writes messages in “thin-air”); Proximity Switch; Structured Cabling For Computer Networks. September 2000: Swimming Pool Alarm; 8-Channel PC Relay Board; Fuel Mixture Display For Cars, Pt.1; Protoboards – The Easy Way Into Electronics, Pt.1; Cybug The Solar Fly. October 2000: Guitar Jammer; Breath Tester; Wand-Mounted Inspection Camera; Subwoofer For Cars; Fuel Mixture Display, Pt.2. November 2000: Santa & Rudolf Chrissie Display; 2-Channel Guitar Preamplifier, Pt.1; Message Bank & Missed Call Alert; Protoboards – The Easy Way Into Electronics, Pt.3. December 2000: Home Networking For Shared Internet Access; White LED Torch; 2-Channel Guitar Preamplifier, Pt.2 (Digital Reverb); Driving An LCD From The Parallel Port; Index To Vol.13. January 2001: How To Transfer 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. February 2001: An Easy Way To Make PC Boards; L’il Pulser Train Controller; A MIDI Interface For PCs; Build The Bass Blazer; 2-Metre Groundplane Antenna; LP Doctor – Clean Up Clicks & Pops, Pt.2. March 2001: Making Photo Resist PC Boards; Big-Digit 12/24 Hour Clock; Parallel Port PIC Programmer & Checkerboard; Protoboards – The Easy Way Into Electronics, Pt.5; A Simple MIDI Expansion Box. April 2001: A GPS Module For Your PC; Dr Video – An Easy-To-Build Video Stabiliser; Tremolo Unit For Musicians; Minimitter FM Stereo Transmitter; Intelligent Nicad Battery Charger. May 2001: 12V Mini Stereo Amplifier; Two White-LED Torches To Build; PowerPak – A Multi-Voltage Power Supply; Using Linux To Share An Internet Connection, Pt.1; Tweaking Windows With TweakUI. June 2001: Universal Battery Charger, Pt.1; Phonome – Call, Listen In & Switch Devices On & Off; Low-Cost Automatic Camera Switcher; Using Linux To Share An Internet Connection, Pt.2; A PC To Die For, Pt.1. December 2002: Receiving TV From Satellites; Pt.1; The Micromitter Stereo FM Transmitter; Windows-Based EPROM Programmer, Pt.2; SuperCharger For NiCd/NiMH Batteries; Pt.2; Simple VHF FM/AM Radio; Using Linux To Share An Optus Cable Modem, Pt.2. January 2003: Receiving TV From Satellites, Pt 2; SC480 50W RMS Amplifier Module, Pt.1; Gear Indicator For Cars; Active 3-Way Crossover For Speakers; Using Linux To Share An Optus Cable Modem, Pt.3. February 2003: PortaPal PA System, Pt.1; SC480 50W RMS Amplifier Module, Pt.2; Windows-Based EPROM Programmer, Pt.3; Using Linux To Share An Optus Cable Modem, Pt.4; Fun With The PICAXE, Pt.1. March 2003: LED Lighting For Your Car; Peltier-Effect Tinnie Cooler; PortaPal PA System, Pt.2; 12V SLA Battery Float Charger; Little Dynamite Subwoofer; Fun With The PICAXE, Pt.2 (Shop Door Minder). April 2003: Video-Audio Booster For Home Theatre Systems; Telephone Dialler For Burglar Alarms; Three PIC Programmer Kits; PICAXE, Pt.3 (Heartbeat Simulator); Electric Shutter Release For Cameras. May 2003: Widgybox Guitar Distortion Effects Unit; 10MHz Direct Digital Synthesis Generator; Big Blaster Subwoofer; Printer Port Simulator; PICAXE, Pt.4 (Motor Controller). June 2003: PICAXE, Pt.5; PICAXE-Controlled Telephone Intercom; PICAXE-08 Port Expansion; Sunset Switch For Security & Garden Lighting; Digital Reaction Timer; Adjustable DC-DC Converter For Cars; Long-Range 4-Channel UHF Remote Control. July 2003: Smart Card Reader & Programmer; Power-Up Auto Mains Switch; A “Smart” Slave Flash Trigger; Programmable Continuity Tester; PICAXE Pt.6 – Data Communications; Updating The PIC Programmer & Checkerboard; RFID Tags – How They Work. August 2003: PC Infrared Remote Receiver (Play DVDs & MP3s On Your PC Via Remote Control); Digital Instrument Display For Cars, Pt.1; Home-Brew Weatherproof 2.4GHz WiFi Antennas; PICAXE Pt.7. September 2003: Robot Wars; Krypton Bike Light; PIC Programmer; Current Clamp Meter Adapter For DMMs; PICAXE Pt.8 – A Data Logger; Digital Instrument Display For Cars, Pt.2. October 2003: PC Board Design, Pt.1; JV80 Loudspeaker System; A Dirt Cheap, High-Current Power Supply; Low-Cost 50MHz Frequency Meter; Long-Range 16-Channel Remote Control System. November 2003: PC Board Design, Pt.2; 12AX7 Valve Audio Preamplifier; Our Best Ever LED Torch; Smart Radio Modem For Microcontrollers; PICAXE Pt.9; Programmable PIC-Powered Timer. December 2003: How To Receive Weather Satellite Images; SelfDiagnostics Plug For Cars; PC Board Design, Pt.3; VHF Receiver For Weather Satellites; Linear Supply For Luxeon 1W Star LEDs; 5V Meter Calibration Standard; PIC-Based Car Battery Monitor; PICAXE Pt.10. July 2001: The HeartMate Heart Rate Monitor; Do Not Disturb Tele­phone Timer; Pic-Toc – A Simple Alarm Clock; Fast Universal Battery Charger, Pt.2; A PC To Die For, Pt.2; Backing Up Your Email. January 2004: Studio 350W Power Amplifier Module, Pt.1; HighEfficiency Power Supply For 1W Star LEDs; Antenna & RF Preamp For Weather Satellites; Lapel Microphone Adaptor For PA Systems; PICAXE-18X 4-Channel Datalogger, Pt.1; 2.4GHZ Audio/Video Link. August 2001: DI Box For Musicians; 200W Mosfet Amplifier Module; Headlight Reminder; 40MHz 6-Digit Frequency Counter Module; A PC To Die For, Pt.3; Using Linux To Share An Internet Connection, Pt.3. February 2004: PC Board Design, Pt.1; Supply Rail Monitor For PCs; Studio 350W Power Amplifier Module, Pt.2; Shorted Turns Tester For Line Output Transformers; PICAXE-18X 4-Channel Datalogger, Pt.2. September 2001: Making MP3s; Build An MP3 Jukebox, Pt.1; PCControlled Mains Switch; Personal Noise Source For Tinnitus; Directional Microphone; Using Linux To Share An Internet Connection, Pt.4. March 2004: PC Board Design, Pt.2; Build The QuickBrake For Increased Driving Safety; 3V-9V (or more) DC-DC Converter; ESR Meter Mk.2, Pt.1; PICAXE-18X 4-Channel Datalogger, Pt.3. November 2001: Ultra-LD 100W/Channel Stereo Amplifier, Pt.1; Neon Tube Modulator For Cars; Audio/Video Distribution Amplifier; Build A Short Message Recorder Player; Useful Tips For Your PC. April 2004: PC Board Design, Pt.3; Loudspeaker Level Meter For Home Theatre Systems; Dog Silencer; Mixture Display For Cars; ESR Meter Mk.2, Pt.2; PC/PICAXE Interface For UHF Remote Control. December 2001: IR Transceiver For PCs; 100W/Ch Stereo Amplifier, Pt.2; Pardy Lights Colour Display; PIC Fun – Learning About Micros. May 2004: Amplifier Testing Without High-Tech Gear; Component Video To RGB Converter; Starpower Switching Supply For Luxeon Star LEDs; Wireless Parallel Port; Poor Man’s Metal Locator. January 2002: Touch And/Or Remote-Controlled Light Dimmer, Pt.1; A Cheap ’n’Easy Motorbike Alarm; 100W /Channel Stereo Amplifier, Pt.3; Build A Raucous Alarm; FAQs On The MP3 Jukebox. February 2002: 10-Channel IR Remote Control Receiver; 2.4GHz High-Power Audio-Video Link; Touch And/Or Remote-Controlled Light Dimmer, Pt.2; Booting A PC Without A Keyboard; 4-Way Event Timer. March 2002: Mighty Midget Audio Amplifier Module; 6-Channel IR Remote Volume Control, Pt.1; RIAA Pre­-­Amplifier For Magnetic Cartridges; 12/24V Intelligent Solar Power Battery Charger. April 2002:Automatic Single-Channel Light Dimmer; Pt.1; Water Level Indicator; Multiple-Output Bench Power Supply; Versatile Multi-Mode Timer; 6-Channel IR Remote Volume Control, Pt.2. May 2002: 32-LED Knightrider; The Battery Guardian (Cuts Power When the Battery Voltage Drops); Stereo Headphone Amplifier; Automatic Single-Channel Light Dimmer; Pt.2; Stepper Motor Controller. August 2002: Digital Instrumentation Software For PCs; Digital Storage Logic Probe; Digital Therm./Thermostat; Sound Card Interface For PC Test Instruments; Direct Conversion Receiver For Radio Amateurs. September 2002: 12V Fluorescent Lamp Inverter; 8-Channel Infrared Remote Control; 50-Watt DC Electronic Load; Spyware – An Update. October 2002: Speed Controller For Universal Motors; PC Parallel Port Wizard; Cable Tracer; AVR ISP Serial Programmer; 3D TV. November 2002: SuperCharger For NiCd/NiMH Batteries, Pt.1; Windows-Based EPROM Programmer, Pt.1; 4-Digit Crystal-Controlled Timing Module; Using Linux To Share An Optus Cable Modem, Pt.1. siliconchip.com.au June 2004: Dr Video Mk.2 Video Stabiliser; Build An RFID Security Module; Fridge-Door Alarm; Courtesy Light Delay For Cars; Automating PC Power-Up; Upgraded Software For The EPROM Programmer. July 2004: Silencing A Noisy PC; Versatile Battery Protector; Appliance Energy Meter, Pt.1; A Poor Man’s Q Meter; Regulated High-Voltage Supply For Valve Amplifiers; Remote Control For A Model Train Layout. August 2004: Video Formats: Why Bother?; VAF’s New DC-X Generation IV Loudspeakers; Video Enhancer & Y/C Separator; Balanced Microphone Preamp; Appliance Energy Meter, Pt.2; 3-State Logic Probe. September 2004: Voice Over IP (VoIP) For Beginners; WiFry – Cooking Up 2.4GHz Antennas; Bed Wetting Alert; Build a Programmable Robot; Another CFL Inverter. October 2004: The Humble “Trannie” Turns 50; SMS Controller, Pt.1; RGB To Component Video Converter; USB Power Injector; Remote Controller For Garage Doors & Gates. November 2004: 42V Car Electrical Systems; USB-Controlled Power Switch (Errata Dec. 2004); Charger For Deep-Cycle 12V Batteries, Pt.1; Driveway Sentry; SMS Controller, Pt.2; PICAXE IR Remote Control. December 2004: Build A Windmill Generator, Pt.1; 20W Amplifier Module; Charger For Deep-Cycle 12V Batteries, Pt.2; Solar-Powered Wireless Weather Station; Bidirectional Motor Speed Controller. January 2005: Windmill Generator, Pt.2; Build A V8 Doorbell; IR Remote Control Checker; 4-Minute Shower Timer; The Prawnlite; Sinom Says Game; VAF DC-7 Generation 4 Kit Speakers. February 2005: Windmill Generator, Pt.3; USB-Controlled Electro- cardiograph; TwinTen Stereo Amplifier; Inductance & Q-Factor Meter, Pt.1; A Yagi Antenna For UHF CB; $2 Battery Charger. March 2005: Windmill Generator, Pt.4; Sports Scoreboard, Pt.1; Swimming Pool Lap Counter; Inductance & Q-Factor Meter, Pt.2; Shielded Loop Antenna For AM; Cheap UV EPROM Eraser; Sending Picaxe Data Over 477MHz UHF CB; $10 Lathe & Drill Press Tachometer. April 2005: Install Your Own In-Car Video (Reversing Monitor); Build A MIDI Theremin, Pt.1; Bass Extender For Hifi Systems; Sports Scoreboard, Pt.2; SMS Controller Add-Ons; A $5 Variable Power Supply. May 2005: Getting Into Wi-Fi, Pt.1; Build A 45-Second Voice Recorder; Wireless Microphone/Audio Link; MIDI Theremin, Pt.2; Sports Scoreboard, Pt.3; Automatic Stopwatch Timer. June 2005: Wi-Fi, Pt.2; The Mesmeriser LED Clock; Coolmaster Fridge/ Freezer Temperature Controller; Alternative Power Regular; PICAXE Colour Recognition System; AVR200 Single Board Computer, Pt.1. July 2005: Getting Into Wi-Fi, Pt.3; Remote-Controlled Automatic Lamp Dimmer; Lead-Acid Battery Zapper; Serial Stepper Motor Controller; AVR200 Single Board Computer, Pt.2; Salvaging & Using Thermostats; Unwired Modems & External Antennas; PICAXE in Schools, Pt.3. August 2005: Mudlark A205 Valve Stereo Amplifier, Pt.1; Programmable Flexitimer; Carbon Monoxide Alert; Serial LCD Driver; Enhanced Sports Scoreboard; Salvaging Washing Maching Pressure Switches. September 2005: Build Your Own Seismograph; Bilge Sniffer For Boats; VoIP Analog Phone Adaptor; Mudlark A205 Valve Stereo Amplifier, Pt.2; PICAXE in Schools, Pt.4. October 2005: A Look At Google Earth; Dead Simple USB Breakout Box; Studio Series Stereo Preamplifier, Pt.1; Video Reading Aid For Vision Impaired People; Simple Alcohol Level Meter; Ceiling Fan Timer. November 2005: Good Quality Car Sound On The Cheap; Pt.1; Microbric – Robotics For Everyone; PICAXE In Schools, Pt.5; Studio Series Stereo Headphone Amplifier; Build A MIDI Drum Kit, Pt.1; Serial I/O Controller & Analog Sampler; Delta XL02 Tower Loudspeaker System. December 2005: Good Quality Car Sound On The Cheap; Pt.2; Building The Ultimate Jukebox, Pt.1; Universal High-Energy Ignition System, Pt.1; Remote LED Annunciator For Queue Control; Build A MIDI Drum Kit, Pt.2; 433MHz Wireless Data Communication. January 2006: Holden’s EFIJY Show Car; Pocket TENS Unit For Pain Relief; “Little Jim” AM Radio Transmitter; Universal High-Energy Ignition System, Pt.2; Building The Ultimate Jukebox, Pt.2; Build A MIDI Drum Kit, Pt.3; Picaxe-Based 433MHz Wireless Thermometer; A Human-Powered LED Torch For Next To Nothing. February 2006: Electric-Powered Model Aircraft, Pt.1; Do-It-Yourself Electronic Servicing; PC-Controlled Burglar Alarm System, Pt.1; Build A Charger For iPods & MP3 Players; Picaxe-Powered Thermostat & Temperature Display; Build A MIDI Drum Kit, Pt.4; Building The Ultimate Jukebox, Pt.3. March 2006: The Electronic Camera, Pt.1; PC-Controlled Burglar Alarm System, Pt.2; Low-Cost Intercooler Water Spray Controller; AVR ISP SocketBoard; Phone/Fax Missed Call Alert; Build A Low-Cost Large Display Anemometer. April 2006: The Electronic Camera, Pt.2; Studio Series Remote Control Module (For A Stereo Preamplifier); 4-Channel Audio/Video Selector; Universal High-Energy LED Lighting System, Pt.1; Picaxe Goes Wireless, Pt.1 (Using the 2.4GHz XBee Modules). May 2006: Lead-Acid Battery Zapper & Condition Checker; Universal High-Energy LED Lighting System, Pt.2; Passive Direct Injection (DI) Box For Musicians; Remote Mains Relay Box; Vehicle Voltage Monitor; Picaxe Goes Wireless, Pt.2; Boost Your XBee’s Range Using Simple Antennas; Improving The Sound Of Salvaged Loudspeaker Systems. June 2006: Television – The Elusive Goal, Pt.1; Electric-Powered Model Aircraft, Pt.2; Pocket A/V Test Pattern Generator; Two-Way SPDIF-to-Toslink Digital Audio Converter; Build A 2.4GHz Wireless A/V Link; Starship “Enterprise” Door Sounder; A High-Current Battery Charger For Almost Nothing. July 2006: Television – The Elusive Goal, Pt.2; Mini Theremin Mk.2, Pt.1; Programmable Analog On-Off Controller; Studio Series Stereo Preamplifier; PC-Controlled Mains Switch, Mk.2; Stop Those Zaps From Double-Insulated Equipment. August 2006: Video Projector Survey; Television – The Elusive Goal, Pt.3; Novel Picaxe-Based LED Chaser Clock; Build A Magnetic Cartridge Preamplifier; An Ultrasonic Eavesdropper; Multi-Throttle Control For PC Flight Simulators; Mini Theremin Mk.2, Pt.2. September 2006: Thomas Alva Edison – Genius, Pt.1; Transferring Your LPs To CDs & MP3s; Turn an Old Xbox Into A $200 Multimedia Player; Picaxe Net Server, Pt.1; Build The Galactic Voice; Aquarium Temperature Alarm; S-Video To composite Video Converter. October 2006: Thomas Alva Edison – Genius, Pt.2; Review – The CarChip E/X (Logs All Sorts Of Data); LED Tachometer With Dual Displays, Pt.1; UHF Prescaler For Frequency Counters; Infrared Remote Control Extender; Picaxe Net Server, Pt.2; Easy-To-Build 12V Digital Timer Module; Build A Super Bicycle Light Alternator. PLEASE NOTE: issues not listed have sold out. All other issues are in stock. We can supply photostat copies of articles from sold-out issues for $A9.50 each within Australia or $A13.00 each overseas (prices include 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 can be downloaded free from our web site: www.siliconchip.com.au November 2006  103 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; or send an email to silchip<at>siliconchip.com.au Questions on the Playmaster Pro series 3 As a complete novice, I hope you can help before I start building the Playmaster Pro Series 3 (“Electronics Australia”, February & March 1994). My reading recommends snubbing capacitors for the bridge rectifier. Is this a good thing and needed? Where do I find appropriate values and what about heatsinking for this unit? What about a bypass capacitor for the AC input to remove RF? Would high frequency stability be improved with the addition of a small value choke on the speaker output? Now for the stupid question, as I cannot find the answer in any of the books I have read: how can it be possible to force 250W of amplifier output through four 5W source resistors? How can something that is rated at 5W handle the output from a power transistor that can put out 10 times that? What stops them from melting or burning out? Lastly, there is now a 500VA toroidal available from Jaycar. Would there be any improvement in stability and transient handling ability by upgrading the power supply side using the larger transformer (with upgraded reservoir capacitors and 5A fuses)? (T. M., via email). • There should be no need for snubbing capacitors across rectifier diodes in audio power amplifiers. We have not seen them used. Nor should there be any need for a bypass capacitor across the AC input. The amplifier does have a Zobel RC Possible Lightning Damage To SMS Controller I purchased the SMS Controller kit (October & November 2005 issues) about 18 months ago and have had no problems at all with it until now. The unit is installed on a yacht and is used to indicate an alarm trigger but is also used to turn a 12V fridge on and off via relay. Recently, I didn’t get an SMS response back to “OK” that the fridge was on and thought it to be a bit odd. I investigated this to find the power LED was on but found that none of the other LEDs were working and the large resistor next to the fuse had burned out. Will it be a matter of replacing this component? I just need to know what could have caused this and whether the rest of the circuit is damaged. The yacht’s power supply is 12V but through regulated solar charging and boost charging, battery levels could reach 14.5V. Could this have done it? (A. L., via email). • The burnt resistor may be the 104  Silicon Chip result of an indirect lightning strike. In a scenario like this, zener diodes ZD1 and/or ZD2 would typically fail short-circuit and blow the fuse. However, as the power LED is on, we must assume that there isn’t a short circuit across the power rail and the fuse must be intact. The resistor (although burnt) must also be intact, although it will probably measure high. Start off by replacing the burnt resistor, then remove all of the ICs from their sockets. Disconnect the phone and power up. Check the output of REG1. It must measure 5V as detailed in the instructions. If not, check for overheating in all other on-board components. The regulator itself may also be faulty. If the 5V supply measures OK, power off and plug the ICs back in. Power up again and check for normal operation. If the unit is still dead, the chances are that the highvoltage spike has damaged one or more of the ICs. network at the output so there should be no need for an extra choke. Nor is there much point in upgrading the power supply. The bridge rectifiers in the power supply are mounted on the chassis and this should be adequate as a heatsink. In any case, we are not able to make more detailed comments about this design. As far as the emitter resistors are concerned, they are of very low resistance and therefore dissipate very little power themselves when the amplifier is delivering full output. To be specific, when the amplifier is delivering 185W into 8 ohms, the current through the FET source resistors will be 4.8A. Therefore the power dissipated in the four 0.22W resistors will be only about 2.5W or 635 milliwatts in each resistor. As a final comment, the Pro Series 3 is a difficult amplifier for the novice to build and the FET output stages can be prone to oscillation problems at frequencies around 100MHz or higher. We would recommend you have a look instead at the Ultra-LD Stereo Amplifier described in the November & December 2001 and January 2002 issues and available as a kit from Altronics. It also involves a fair amount of work to assemble but has proved to be more trouble-free than the Pro Series 3. Soft-start lamp circuit wanted Have you published a circuit for a zero crossing, soft-start switching device for lamps that can blow at switch-on? (B. C., via email). • There are several approaches to this problem. The first was the ideal solution: a Lamp Saver circuit published in the June 1986 issue of “Electronics Australia”. However, it used a 2N4992 SBS device which is very difficult to obtain now. We also published a soft start circuit for lamps in the Circuit Notebook section of the September 1991 issue but no PC board was published. siliconchip.com.au Modifications To The Big Digit Clock I am interested in purchasing the PIC Programmer kit featured in the March 2001 issue of SILICON CHIP. I would like to know if this unit is capable of programming other PICs. Is the PIC 16F628 software and electrically compatible to the 16F84? I want to use 16F628 in place of the 16F84 in the Big Digit Clock project featured in the same magazine. A further modification I would like to try with the clock is the use of larger digits of around 100mm to 120mm. Could the use of higher current rated transistors in place of BC328s Q1-Q8 with the same biasing be OK or would further modifications be necessary? (G. W., via email). • The 16F628A is pin-compatible with the 16F84A. However, due to increased functions within the 16F628A, assembly language pro- Finally, the Touch Lamp Dimmer published in the July 2005 issue does include a soft start feature. No zero-crossing power control circuit involving Triacs can be used for lamp control because the technique of switching blocks of 50Hz gives rise to severe flicker. Wrong current from electronic load I have assembled the Versatile Electronic Load from Circuit Notebook of the March 2006 edition. With a 15.4V power supply connected to this unit, I can only produce a load current of 1.35A. With 15.4V at the MOSFET drain and 7.71V at the gate, I have 7.41V at the MOSFET source. The MOSFET Safe Operating Area diagram indicates that at 15V applied, I should theoretically be able to draw approximately 4.25A. Can you help? (P. A., via email). • If you are only achieving a total load current of 1.35A when there is 7.41V at the MOSFET source, that suggests that the resistance to ground in the “3” position of switch S1 is about 5.48W (7.41/1.35), rather than the 1W which should be produced with the network of resistors shown in the Electronic Load circuit. If the resistance to ground siliconchip.com.au grams from the 16F84A will probably need modifications before they will run on the newer device. We suggest that you stick with the 16F84A in the clock project unless you have the skills to modify the source code appropriately. It’s available from our website. Although the PIC Programmer & Checkerboard was not intended for use with the 16F627/8, it can be used with these new pincompatible devices with a small modification. You’ll need to install a resistor between pin 10 of the PIC socket (IC2) and ground. The purpose of this resistor is to ensure that the RB4/PGM pin is at logic low level during programming, so preventing inadvertent selection of the 16F627/628 LVP (Low Voltage Pro­ gramming) mode. was correct (1W), you’d be able to measure only 1.35V at the MOSFET source for a load current of 1.35A and 4.25V for a load current of 4.25A. So your measurements suggest that there is something wrong with the resistors making up your “1-ohm” current range resistance; ie, the four 4.7W/10W resistors or the 2 x 15W/5W resistors. It would therefore be a good idea to check these resistors carefully. For example if the four 10W resistors were really 47W instead of 4.7W, this would give a “range 3” resistance of very close to 5.48W, instead of the correct 1W. Running CCTV cameras from a switching supply I have recently acquired an uninterruptible power supply made by Tactical Technologies which has a supply output of 13.8V DC at 5A. Can this be used to supply CCTV cameras rated at 12V? (D. G., via email). • Ideally, it should be adjusted to provide 12V; an internal adjustment should be available. Be careful though – if it’s a switchmode supply, part of the circuitry may be floating at 240VAC! If there’s no adjustment, connect three diodes in series to drop the voltage to 12V. However, if it has Choose a value of about 100kW so that it doesn’t interfere too much with the 10kW pullup resistor. Also, make sure that pole 5 of DIPSW6 is open during programming. Note also that the software described in the article is now out of date and will not run on Windows 2000/XP. We’re now recommending “WinPic”, which can be obtained from http://people.freenet. de/dl4yhf/winpicpr.html. Select an interface type of “Tait, 7407 driver +PNP transistor” on the “Interface” tab for use with this programmer. Regarding the use of larger displays in the Big Digit 12/24 Hour Clock, it all depends on the specifications of the proposed devices. It may well be that a higher voltage (rather than higher current) rail is needed, if the larger displays use more than four LEDs in series. residual switchmode hash, it might interfere with the video signal from the cameras. Load impedance of the JV60 Some time ago I remember a speaker project that SILICON CHIP published that employed two (Vifa?) bass drivers connected in parallel for the low-end response. However, the second driver also had an inductor in series with it, to act as a low-pass filter at the -3dB point of the first. This effectively extended the overall bass response by using that of the second driver to supplement that of the first, without affecting frequencies above the -3dB point. My question is: what impedance does the amplifier see? Does it see (assuming 8-ohm drivers) 8W down to the -3dB point of the first, then 4W below that? Or does it see 4W across all frequencies handled by the bass drivers? I’m assuming that this therefore has an impact on the electrical sensitivity of the system. (P. S., Lane Cove, NSW. • The system in question was probably the JV60 described in the August 1995 issue. The practical answer is in the impedance curve which was November 2006  105 Running A Quartz Clock At Half Speed Is it possible to modify a quartz clock mechanism for 24-hour operation; ie, to run at half speed? (T. B., via email). • Not only is it possible but because we were feeling extremely generous, we knocked up the circuit shown above to the do the job. published in the article. It showed the system as having a nominal impedance of 8W. The woofers are effectively never in parallel since they both have their own crossover network. How about a chip amplifier? I have been looking at your amplifier projects from the past few years and one thing you have never attempted is 106  Silicon Chip Fig.1 shows the circuit of a typical quartz clock. The clock IC uses a 38kHz crystal and divides it down to provide narrow pulses every 2s which drive the motor escapement. Our modified circuit in Fig.2 uses the 32kHz crystal in an external oscillator and feeds it to a flipflop a chip amplifier. These are very simple, utilise cheap National Semiconductor ICs and give off minimal heat. Sites such as www.chipamp.com are a good reference. One using the LM4780 chip would give out 120W RMS into 8W or 60W into 8W depending on the configuration. (N. M., via email). • We have had many hybrid amplifiers over the years: December 1993 (LM1875); February 1994 (LM3876); March & April 1995 (LM3886); October & November 1996 (TDA1519A); to derive 16kHz. This is then fed to the clock chip’s oscillator input, whereupon it is divided down to narrow complementary pulses every 4s. Note that CMOS chips IC1 & IC2 run from 3V, while the clock chip is run from the normal 1.5V supply. May 2001 (TDA1519A); March 2002 (TDA1562Q); February & March 2003 (TDA1562Q); December 2004 (LM1875). By the way, since all these amplifiers are essentially class-B designs they don’t give off any less heat than an equivalent amplifier design using discrete components. We had a quick look at the specifications of the LM4780 and as far as we can see, it has little to recommend it compared to our current designs using siliconchip.com.au discrete transistors. Both its distortion and noise figures are fairly average. Indeed, it is safe to say that no hybrid amplifier chip presently available gives a better performance than a carefully designed amplifier using discrete components. The advantage of the hybrids is generally lower cost, simple assembly and no need for adjustments. Tacho has wrong supply connection I have built the digital tacho from the April 2000 issue of SILICON CHIP. Could you please tell me if there is a modification to correct the problem that when the car is started, often the tachometer does not register. I have had to wire in a switch to totally disconnect it from power until the engine is running so that it reads correctly. If it is connected when the car is started, it often reads nothing. (J. G., via email). • You have probably connected the tachometer to a supply point that is switched off when the car is starting. Check that the supply from the car for the tachometer input does not drop to below about 9V when starting. Carbon pile battery tester wanted I am looking to build a carbon pile battery tester. Is there a kit available to make one? Are there suppliers that sell adjustable carbon piles? (S. R., via email). • While carbon pile battery testers are still being made, they are a bit old hat. We have not described one. Newer battery testers use a switch- mode circuit which pulls very heavy but short current pulses from the battery. In fact, the Condition Checker in our Battery Zapper featured in the May 2006 issue uses the same principle. Missed Call Alert is locked up Both myself and a friend have constructed the Phone/Fax Missed Call project and both of us are having identical problems. When powered up, we get a constant call alert signal. The reset switch discharges the capacitor but has little change on the output from pin 10 on the flipflop, inputs from pins 5 & 8 are as per the article but there is a constant 6.48V on pins 9, 6 & 10. There is also a 5V drop on the 100W resistor at the input. When the reset switch is pushed, pin 5 goes low and the voltage on pins 9, 6 and 10 increases slightly to 6.55V but no change to Q1 and the call alert. Any assistance would be appreciated as we seem to be at a dead end. (N. L. via email) • From your description, it sounds as if the pin 8 input of the IC1b/IC1c flipflop is being held down at logic low level and thus keeping the flipflop in its “set” state. You don’t provide any voltages for the circuitry involving IC1a and IC1d but we suggest you check this section carefully because the problem may be in this area. In the absence of any calls, pin 1 of IC1a should be at almost +12V while pins 3 & 13 should be down at almost 0V, pin 12 at +0.6V and pin 11 (the output of IC1d) should be again close to +12V. These voltages should only switch to their opposite logic levels Notes & Errata PIC Programmer & TestBed, October 2001: the PicProg software described in the article is outdated and will not work on recent model PCs. A suitable alternative is WinPIC, which can be obtained from http://people.freenet.de/dl4yhf/ winpicpr.html Before use, configure WinPIC to use an interface type of “COM84 programmer for serial port” and select the correct COM port from the drop-down list. These settings can be found on the “Interface” tab. Galactic Voice. September 2006: the panel in Fig.6 and in the photographs on pages 67 & 72 show the Effect and Depth labelling reversed. The Effects control should be in the middle. during the ring tone of an incoming call; pin 1 should go low, pins 3, 13 & 12 should go high and pin 11 should go low. If this does not occur, you may have a problem in either this section of the circuit or in the circuitry on the “phone line” side of the optocoupler. Just a suggestion: are you connecting the Missed Call Alerts onto phone lines carrying ADSL broadband links but before the ADSL filter? If so, your problems may be caused by almost constant triggering by the ADSL carriers on the line. In this case, the solution would be to fit an ADSL filter in the phone line ahead of the Missed SC Call Alert. 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. siliconchip.com.au November 2006  107 ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. PRACTICAL RF HANDBOOK AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* Alternative fuel expert Carl Vogel gives you a hands-on guide with A guide to RF design for engineers, technicians, students and enthusiasts. the latest technical information and easy-to-follow instructions Covers key topics in RF: analog design principles, transmission lines, for building a two-wheeled electric vehicle – from a streamlined couplers, transformers, amplifiers, oscillators, modulation, transmitters and scooter to a full-sized motorcycle. 384 pages in soft cover. receivers, propagation and antennas. 279 pages in paperback. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. PRACTICAL RF HANDBOOK AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* Alternative fuel expert Carl Vogel gives you a hands-on guide with A guide to RF design for engineers, technicians, students and enthusiasts. the latest technical information and easy-to-follow instructions Covers key topics in RF: analog design principles, transmission lines, for building a two-wheeled electric vehicle – from a streamlined couplers, transformers, amplifiers, oscillators, modulation, transmitters and scooter to a full-sized motorcycle. 384 pages in soft cover. receivers, propagation and antennas. 279 pages in paperback. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). 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To book your classified ad, email the text to silicon<at>siliconchip.com.au and include your credit card details, or fax (02) 9939 2648, or post to Silicon Chip Classifieds, PO Box 139, Collaroy, NSW, Australia 2097.   Enclosed is my cheque/money order for $­__________ or please debit my o Bankcard   o Visa Card   o Master Card Card No. Signature­­­­­­­­­­­­__________________________ Card expiry date______/______ Name _____________________________________________________ Street _____________________________________________________ Suburb/town ___________________________ Postcode______________                  SPK360 3/5/06 1:10 PM  Page 1 Phone:_____________ Fax:_____________ Email:__________________ 20 years experience! More control solutions for you! NEW K145Server: monitor temperatures in server rooms, hothouses etc remotely over the web for less than $100. NEW 500oz-in plus Stepper Motor: may not be the fastest motor on the block but it has real grunt. NEW DC Motor Controllers from Pololu: these motor controllers have been designed for robotic applications. Range from mini dual 1A controllers to 30A. NEW Servo Motor Controllers from Pololu: control your R/C servo motors with our serial servo controllers Ideal for robotic applications. Control up to 8 servos with the one card. Netiom Link: automatically transfer digital inputs and outputs between two cards over an Ethernet link. Electronic Thermostats with digital temperature display; two control relays; can be used in heating and cooling. 110  Silicon Chip NTC thermistor or J T/C or Pt100 sensors. Low Cost Mini Panel Meter Displays: programmable 4-20mA $155 and Tacho­ meter $129. Isolated RS232 to RS485 convert­ ers. USB to RS422/RS485 converter with 1500V Isolation, RTS or Auto Data Flow control. Signal Conditioners non isolated and isolated: convert thermocouples, RTDs to 4-20mA or 0-10V Fully pro­ grammable. Stepper Motors: we have a selection of Stepper motors for hobby and high torque CNC applications. DC Motors for both hobby and high torque applications. DC, Stepper and Servo Motor controller kits. Serial and Parallel Port relay controller cards. PIC MicroProgrammers: serial and USB port operated. HI-FISPEAKER REPAIRS YOUR EXPERT SPEAKER REPAIR SPECIALISTS Specialising in UK, US and Danish brands. Speakerbits are your vintage, rare and collectable speaker repair experts. Foam surrounds, voice coils, complete recone kits and more. Original OEM parts for Scan-Speak, Dynaudio, Tannoy, JBL, ElectroVoice and others! SPK360 FOR SALE tel: 03 9647 7000 www.speakerbits.com Switch Mode, Battery Chargers and DC-DC converters. Full details and credit card ordering available at www.oceancontrols.com. au Helping to put you in control. WEATHER STATIONS: windspeed & direction, inside temperature, outside temperature and windchill. Records highs and lows with time and date as they occur. Optional rainfall and PC interface. Used by government departments, farmers, pilots and weather enthusiasts. Other models with barometric pressure, siliconchip.com.au Satellite TV Reception VIDEO - AUDIO - PC 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°. distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates 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 ELNEC IC PROGRAMMERS High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP Our company has been a leading designer, manufacturer & wholesaler of electronic security & technology products since 1978. We need passionate & experienced sales and technical staff to join us in providing the best service to our wholesale customers around the world. 2 x 100MSa/s 10bit inputs + trigger 100MHz bandwidth 8 x digital inputs 4M samples/input Sig-gen + spectrum analyser Windows 98/Me/NT/2k/XP IMAGECRAFT C COMPILERS ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 www.grantronics.com.au          DOWNLOAD OUR CATALOG at www.iinet.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS 49a George Street, Kensington WA 6151 Ph: (08) 9367 6330 Fax: (08) 9367 2459 Email: worcom<at>iinet.net      humidity, dew point, solar radiation, UV, leaf wetness, etc. Just phone, fax or write for our FREE catalog and price list. Eco Watch: phone (03) 9761 7040; fax (03) 9761 7050; Unit 5, 17 Southfork Drive, Kilsyth, Victoria 3137. ABN 63 006 399 480. www.davisinstruments.com.au QUALITY LED TORCHES, 1W: Fen­ix L0P & L1P, CIVICTOR V1 use a single AAA or AA cell. 3-watt: Fenix L1T & L2T siliconchip.com.au QUEST ® Quest AV® VGA Splitter VGS2 AWP1 A-V Wallplate GRANTRONICS PTY LTD In the first instance please send your resume to: 9 Hannabus Place, McGraths Hill NSW 2756 Ph: 02 4577 4708 Fax: 02 4577 4885 Email: manager<at>rhino.com.au MD12 Media Distribution Amplifier HQ VGA Cables CLEVERSCOPE USB OSCILLOSCOPES CAREER OPPORTUNITY IN WHOLESALE ELECTRONICS DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters   with 1 or 2 AA cells. Fenix P1/Nuwai QIII & TM-301X-3 use 1 or 2 CR123A cells. The AIT Nightstar uses no batteries at all! www.torchworld.com.au/sc/ Come to the specialists... ® Quest Electronics® Pty Limited abn 83 003 501 282 t/a Questronix Products, Specials & Pricelist at www.questronix.com.au fax (02) 4341 2795 phone (02) 4343 1970 email: questav<at>questronix.com.au www.dontronics.com has 300 selected hardware and software products available from over 40 world wide manufacturers, and authors. Atmel Programmers And Compilers: AVR-ISP USB In-System Programmer, STK500, Codevision C, Bascom AVR, FED AVIDICY Pro, MikroElektronika Basic and Pascal, Flash File support, and boot loaders. PICmicro Programmers And Compilers: microEngineering Labs USB programmers, adapters, and Basic Compilers, DIY (Kitsrus) USB programmers, MikroElektronika Basic, Pascal, DSpic Pascal Compilers, CCS C, FED C, Hi-Tech C, MikroElektronika C, disassembler and hex tools. Other Micros: Tiny Arm, Z80, 8085, etc. hardware and software. CAN: Lawicell CANUSB, CAN232 FTDI: USB Family of IC ‘s. FT232RL, FT2452RL, also BL and others. 4DSystems LCD/Graphics: Add VGA monitor, or 1.5” LCD to your micro. Heaps And Heaps Of USB Products: TTL, RS-232, RS-485, modules, cables, analyzers, CRO’s. Popular Easysync USB To RS-232 Cable: Works when the others fail. Only one recommended by CBUS. Money back guarantee. www.dontronics-shop.com November 2006  111 Do You Eat, Breathe and Sleep TECHNOLOGY? Opportunities for full-time and part-time positions all over Australia & New Zealand Jaycar Electronics is a rapidly growing, Australian owned, international retailer with more than 39 stores in Australia and New Zealand. Our aggressive expansion programme has resulted in the need for dedicated individuals to join our team to assist us in achieving our goals. We pride ourselves on the technical knowledge of our staff. Do you think that the following statements describe you? Please put a tick in the boxes that do: Knowledge of electronics, particularly at component level. Assemble projects or kits yourself for car, computer, audio, etc. Have empathy with others who have the same interest as you. May have worked in some retail already (not obligatory). Have energy, enthusiasm and a personality that enjoys helping people. Appreciates an opportunity for future advancement. Have an eye for detail. Why not do something you love and get paid for it? Please write or email us with your details, along with your C.V. and any qualifications you may have. We pay a competitive salary, sales commissions and have great benefits like a liberal staff purchase policy. Send to: Retail Operations Manager - Jaycar Electronics Pty Ltd P.O. Box 6424 Silverwater NSW 1811 Email: jobs<at>jaycar.com.au Jaycar Electronics is an equal opportunity employer and actively promotes staff from within the organisation. RFMA RF Modules Australia Low Power Wireless Connectivity Specialists Applications: TX2H-433-64-5V Rural UHF FM Transmitter UHF Narrowband Transceiver Utilities In Stock NOW! In Stock NOW! Industrial Range: 500m Range: 500m Power: 25mW Power: 10mW Commercial Data rate: 64kbps Data rate: 10kbps Government Receiver: RX2A-433-64 33mm x 23mm x 12mm Meter Reading RADIOMETRIX: Low Power, Licence Exempt Radio Modules NiM2-434.650-10 RF Modules Australia. P.O. Box 1957 Launceston, TAS., 7250. Ph: 03-6331-6789. Email: sales<at>rfmodules.com.au. Web: rfmodules.com.au Parallax Basic Stamps The awesome simultasking 8-core Propeller Chip. Lots of sensors and Development kits + Robots. Ultrasonics, PIR accelerometer. Serial LCD display, serial keypads. Stepper Motor Controllers & Motors RCS RADIO/DESIGN is at 41 Arlewis St, Chester Hill 2162, NSW Australia and has all the published PC boards from SC, EA, ETI, HE, AEM & others. Ph (02) 9738 0330. sales<at>rcsradio. com.au, www.rcsradio.com.au PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au SWITCHMODE 5V reg. module kit just $6, or $7 built. 10.5 inch 7-segment dis112  Silicon Chip Micro stepping up to 25,600 fully protected industrial grade controllers at incredible prices. PCB mount units with full 32 bit indexer capability. DIN rail mount controller for factory applications. See our website for details and PDF file. Call or email us for application assistance. ron<at>nollet.com.au R T Nollet: Ph (03) 9338 3306; fax (03) 9338 4596; mobile 0407 804 712. www.nollet.com.au play kit from $30. LEDs, nixies, kits, lots of other stuff. www.ledsales.com.au WANTED WANTED: EARLY HIFIs, AMPLIFIERS, Speakers, Turntables, Valves, Books, Quad, Leak, Pye, Lowther, Ortofon, SME, Western Electric, Altec, Marantz, McIntosh, Goodmans, Wharfedale, Tannoy, radio and wireless. Collector/ Hobbyist will pay cash. (07) 5471 1062. johnmurt<at>highprofile.com.au Advertising Index Agilent Technologies...................... 3 Alternative Technology Assoc. ..... 87 Altronics...................51, loose insert Av-Comm................................... 111 BitScope Designs......................... 75 Davis Instruments...................... 111 Dick Smith Electronics............ 20-25 Digital Graphics.......................... 112 Dontronics.................................. 111 Elan Audio.................................... 19 FreeNet Antennas...................... 111 Furzy Electronics........................ 111 Grantronics................................. 111 Harbuch Electronics..................... 95 Instant PCBs.............................. 111 Jaycar ....................... IFC,53-60,112 JED Microprocessors..................... 5 MicroByte Electronics................. 110 Microgram Computers.................. 11 MicroZed Computers.................... 92 Ocean Controls.......................... 110 Oatley Electronics........................ 93 Quest Electronics....................... 111 Radio Parts.............................. OBC RCS Radio................................. 112 RhinoCo Technology.................. 111 RF Modules......................... IBC,112 RS Components........................... 49 RTN............................................ 112 SC – Radio & Hobbies DVD......... 40 Silicon Chip Binders................ 19,62 Silicon Chip Bookshop........ 108-109 Silicon Chip Car Book...... 33,79,101 Silicon Chip Subscriptions........... 61 Sesame Electronics.................. 112 Speakerbits................................ 110 Swann Communications.............. 15 Trusys........................................... 87 Worldwide Elect. Components... 111 PC Boards Printed circuit boards for SILICON CHIP designs can be obtained from RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. 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 siliconchip.com.au siliconchip.com.au November 2006  113