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siliconchip.com.au June 2011  1 Financial Year End Clearance JUNE 2011 Robot Arm Kit with Controller This arm is a must for budding robot enthusiasts and operates just like the real thing. It is capable of 5 separate movements and can easily perform complex tasks. Individual control is available for opening and closing the gripper plus control of wrist, shoulder, elbow and base rotation. The arm is supplied as a kit of parts and makes an excellent project for anyone interested in robotic construction and basic electrical connections. Suitable for ages 12+ •100g lift capacity • Requires 4 x D cells • Base dimensions: 225(L) x 160(W) x 40(H)mm KJ-8916 WAS $69.95 59 95 $ SAVE $10 00 Also available USB Interface Kit For adding computer control via USB to your Robotic Arm. Use a keyboard or mouse to have a real-time control or program, edit and load individual functions and movements. DEAL KJ-8917 49 95 $ Buy both for $90.00 Save $29.90 Wind Powered Generator Experimenters Kit This wind powered generator kit is a great way to learn about green energy and the mechanics of wind generators. It is supplied in kit form, so you get to assemble the whole thing before you start learning about how it works. Includes all the parts to make the generator, fan 95 $ assembly, and pedestal. 49 SAVE $10 00 • Suitable for ages 10+ KJ-6696 WAS $59.95 Asuro Programmable Robot Kit Solar Powered Planetarium Young astronomers will love this mini solar kit. Easy to build and loads of fun. Not only does it provide a hands-on lesson about how solar power drives a motor, but also gives some educational pointers on planets and the solar system. Operates from a 50W halogen light as well. Suitable for ages 10+ Kit Includes: • 6 colours of opaque acrylic paints and paint brush • Planets including Earth, Mars and Jupiter • Solar panel with motor • Detailed instruction manual KJ-8927 WAS $24.95 19 95 69 $ SAVE $5 00 Micro Solar Car Racer Ethanol Bio Fuel Energy Kit Build your own desk fan and run it on your own bio-fuel! Generate your own electricity from ethanol (ethyl alcohol) using Direct Ethanol Fuel Cell technology. Bio fuels are an alternative to fossil fuels as they are generated from fermented plant matter. The kit contains everything you need to get your alternative fuel experiment off the ground, except the ethanol itself. Just use a solution of denatured alcohol which is available from pharmacies, hardware stores or chemical suppliers. So once you’ve made the fuel you can put it to work running the desk top fan you assemble in the kit. The kit includes Ethanol storage tank, tubing, purging valve, supporting base, electric motor, wiring with crocodile clips, fan blades, Ethanol solution mixing 00 $ container and pH measuring strips. 129 • Recommended for ages 12+ • Adult supervision recommended KT-2550 WAS $199.00 In addition to six collision sensors and an optical unit for following a line, Asuro has two odometers and several display elements. The supplied duplex infrared interface permits wireless programming, as well as a remote control with a PC. The "brain" of the robot is a RISC processor that also permits the processing of complex programs. Ideal for hobbyists, school and student projects, schools, training in the electrical engineering and mechatronics fields as well as university course. This is not a kit for the faint-hearted! 95 $ Some soldering required. • 4 x AAA batteries required SAVE $10 00 KR-3120 WAS $79.95 SAVE $70 00 Will work with wine as well! Don't let its miniscule size fool you! Shine a lamp on its solar panel and watch it travel across your desk. Shine a higher powered torch on it and you'll see it take off at a surprisingly furious pace. Comes in its own see-through case. Suitable for ages 8+ • Dimensions: 31(L) x 20(W) x 15(H)mm GT-3750 9 $ 95 DEAL Buy 2 for $15 Save $4.90 Solar Eco-House Kit It's fun to build and will introduce your child to the eco-friendly concepts in an entertaining way. It has its own solar panel and a windmill to supply free power to the lighting & sound circuits, also run from ordinary batteries. Simple and safe for ages 8+. 24 95 $ • Requires 2 x AA batteries for non SAVE $5 00 solar operation KJ-8924 WAS $29.95 DMM Savings! Whether you require a low cost DMM or a new CATIII DMM – Jaycar is the place to get it from. Features include diode & transistor testing, data hold, temperature probes and holsters. For a full range of other DMM and test equipment available see in store or online today. IP67 Rated Cat III Autoranging DMM Frequency DMM • 32 range • Transistor test • Diode test • Audible continuity • Temperature, Capacitance • Holster and temperature probe included • Display: 2000 count • Category: Cat II 600V • Dimensions: 200(H) x 95(W) x 95 $ 45(D)mm QM-1320 SAVE $5 00 WAS $24.95 19 To order call • IP67 rated • 61 segment analogue display • Relative mode • Data hold 95 $ • Diode test • Audible continuity SAVE $10 00 • Min/max storage mode • Auto or manual range • Auto power-off• Holster included • Display: 6000 count • Category: Cat IV 600V • Dimensions: 182(H) x 82(W) x 55(D)mm QM-1325 WAS $79.95 69 Cat II 4000 Count Autoranging DMM • Autoranging • Data hold • Relative measurement function • Auto power-off 95 • Holster included $ • 10A AC & DC • Display: 4000 count SAVE $5 00 • Category: Cat II 600V • Dimensions: 150(H) x 75(W) x 33(D)mm QM-1535 WAS $29.95 1800 022 888 www.jaycar.com.au Prices valid from 24/5/2011 to 23/06/2011. Limited stock on sale items. No rainchecks. 24 All Savings are based on Original RRP Contents SILICON CHIP www.siliconchip.com.au Vol.24, No.6; June 2011 Fea tures 14 The FutureWave Energy Saver At last: here’ s an energy saver that actually does save energy! It’s specifically intended for use with certain electric motors, especially as used in swimming pool and spa pumps – by Ross Tester 22 Rescuing Electronic Gear After The Flood The devastating Queensland floods wiped out a lot of electronic gear. Here’s how some high-end radio gear was rescued and restored – by Robert Googe 74 HiFi Review: Marantz CD6003 CD Player DVD players can give good results when playing audio CDs but a dedicated CD player is still the best way to go. This high-quality CD player from Marantz features pitch control, a USB input and lots of other goodies – by Leo Simpson 20A 12/24V DC Motor Speed Controller Mk.2 – Page 28. Projects To Build 28 20A 12/24V DC Motor Speed Controller Mk.2 This gutsy little motor speed controller is easy to build and features low-battery protection, soft start and adjustable pulse frequency. It can run from 12V or 24V batteries at currents up to 20A – by John Clarke 36 USB Stereo Recording & Playback Interface Want to use your laptop or PC to record high-quality stereo audio? This USB interface unit features balanced mic inputs, stereo analog line inputs & outputs, an S/PDIF digital audio input and an S/PDIF output – by Jim Rowe 62 VersaTimer/Switch With Self-Latching Relay Do you have a switching application (up to 230VAC) that calls for a relay but needs very low current drain? Here’s a micropower switch that also functions as a programmable timer and/or 12V battery protector – by John Clarke USB Stereo Recording & Playback Interface – Page 36. 80 A Handy USB Breakout Box For Project Development It connects between two USB cables and lets you examine the D+ and Dsignal line activity with your scope and the current flow – by Jim Rowe Special Columns 57 Serviceman’s Log There’s just no pleasing some people – by the Serviceman 83 Circuit Notebook (1) Wireless Doorbell Relay Driver; (2) Microphone Adaptor For A Violin; (3) Diesel Engine Watchdog Circuit Monitors Oil Pressure & Water Temperature; (4) PICAXE-Based Metronome With Accented Beat; (5) Multi-Decade PeriodMultiplier For Precision Frequency Comparisons 90 Vintage Radio VersaTimer Switch With SelfLatching Relay – Page 62. 62. Radio manufacturing in 1925: the Wells Gardner story – by Kevin Poulter Departments   2   4 88 95 Publisher’s Letter Mailbag Product Showcase Order Form siliconchip.com.au 98 Ask Silicon Chip 102 Notes & Errata 103 Market Centre A Handy USB Breakout Box – Page 80. June June 2011  1 2011  1 SILICON SILIC CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc. (Hons.) Technical Editor John Clarke, B.E.(Elec.) Technical Staff Ross Tester Jim Rowe, B.A., B.Sc Nicholas Vinen Photography Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Kevin Poulter 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 is 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: $97.50 per year in Australia. For overseas rates, see the order form 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 ISSN 1030-2662 Recommended and maximum price only. 2  Silicon Chip Publisher’s Letter Let’s forget about a carbon tax and concentrate on the environment instead Since I wrote the Publisher’s Letter entitled “Let’s have no more of this carbon pollution nonsense” in the June 2009 issue of SILICON CHIP, the political climate seems to have changed dramatically – more than I could ever have expected in such a short time. Not only did the Copenhagen climate summit collapse in disarray but there has been a general shift in people’s attitude to climate change. While most people seem to feel that climate change is happening and that human activity is at least partly to blame, there is no consensus on what to do about it. One thing is certain: the science is no longer “settled”, in spite of the increasingly shrill declamations by those who are certainly not disinterested. And it seems that the number of “climate change deniers” has greatly increased. The Federal Government’s move to introduce a “carbon tax” next year has not been favourably received and nor does there seem to be any remotely popular alternative strategy. And there is a growing realisation amongst the populace that action by Australia will have a significant cost and will have major employment ramifications. A tiny reduction in our greenhouse gas emissions when they are already virtually insignificant in the total world emissions means the whole process is futile, if not farcical. All of which means that recent moves by the Greens political party to ramp up the use of renewable energy are worrying. They have a long-term aim of making all energy renewable and hang the consequences, whether it means much higher prices for electricity or lots of job losses – they simply don’t care. In an ideal world, we should not have coal-fired power stations and I have written along these lines in Publisher’s Letters in years past. My opposition to coal-fired power stations comes not from any concern about carbon dioxide – it is not a pollutant – but with the long-term damage to the landscape and water resources, both by open-cut and underground mining. However, there does not seem to be any support by the current Federal Labor government for any reduction in coal mining, whether for use in power stations or for export; quite the contrary in fact. With one eye on the union membership of mines and the power industry and with the other eye on ever-growing royalties and taxes, there is no stomach at all for any reduction; they want more coal mining, not less. And they want other forms of coal exploitation as well, in the form of coal-seam gas projects. Which also means that the current Federal Government’s infatuation with a carbon tax to combat climate change is hypocritical to say the least. We can state that the Greens are consistent in this respect – they want to stop all coal mining. But they pretty much want to stop everything, don’t they? I am coming around to the view that governments should do nothing to combat climate change, since its causes are extremely complex and still not understood. In any case, all previous moves to “do something” by the present government have been seriously misguided, and that is putting it mildly. Nor do I think that there is any need to panic. Even if we are experiencing global warming, as opposed to the much more vague term, “climate change”, there is not likely to be any “tipping point” in the foreseeable future. Secondly, as Climate Change Commissioner Tim Flannery has admitted, any action that we do take is likely to take centuries before it has any measurable effect. Instead, governments should act to promote economic activity while still doing all they can to protect our environment. The two aims are not mutually exclusive. A carbon tax will not have any beneficial effects. Leo Simpson siliconchip.com.au siliconchip.com.au June 2011  3 MAILBAG Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask SILICON CHIP” and “Circuit Notebook”. Coping with wide mains voltage variations In the same issue as your helpful auto-transformer voltage bucking project (Mains Moderator, SILICON CHIP, March 2011) you comment on a related letter on page 104 by suggesting that while ferro-resonant AC voltage regulators are best, you are unsure whether they are still available. Where the mains voltage is fairly constant but is the wrong value, your auto-transformer project naturally is the best economic solution and provided its ratings are not exceeded nothing will be more reliable. However, for someone with very variable voltage, say a household a few miles down the long country line you instance, a better solution than a ferro-resonant transformer might be an on-line or no-break “sinewave” UPS. From time to time they can be bought secondhand on eBay for relatively modest sums, even up to a kVA or two. They are quiet, fairly efficient and apart from the gel cells, tend to be quite reliable. However, as long as Maximite computer is a big hit From the relative isolation of where I sit, the Maximite looks to be a big hit. First, although I owned every issue of ETI & EA from my arrival in Australia (in late December 1977) until the mid 1990s, I have never until now been able to buy SILICON CHIP more than rarely. This arose when my life took me well away from electronics (part career, part disability). This year, the Maximite changed all that and I have bought three consecutive issues. Second, I decided to buy the kit from Altronics. What a friendly and helpful company. Because of demand forecast, I probably will not get my kit before June, although they are working as fast as they can. So 4  Silicon Chip no hold-up is demanded of them, no or only a very modest battery will be needed. Nevertheless you will be pleased to know the ferro-resonant regulators are indeed still manufactured. In addition to Asian sources, the firm that was perhaps the most well-known of the traditional suppliers, Sola of the USA, lists models which are more or less unchanged from 20 years ago, right down to the catalog numbers. You are right that they are pretty expensive new. They are also unavoidably noisy due to the high degree of saturation in the core and for the same reason are pretty lossy and run hot; full load efficiency would not exceed 85% and no load losses are around 8-10% of nameplate rating, which is a significant factor these days if they are run for extended periods. Ratings tended be quite modest. For example whereas units of say 100500VA were plentiful, a 1kVA unit was large, heavy and in my experience not too common. At our home on a rural NZ road I am hoping that Geoff Graham and readers will keep on developing for the Maximite. I must admit to a little surprise. In the old days, EA & ETI were meticulous about mentioning errors and updates in the magazine. I have found online that the originally printed schematic had an error. Although this was mentioned and corrected online, I think you may be a little over-dependent on the internet. On the plus side, I see great potential for this kit, even given my woeful lack of current electronics knowledge. The first thing I’d like to do is add an xxPROM programmer to the IO lines so that I can fix my old much-loved EA DATUM. It appears to need a new ROM and several years ago its designer promised to send one but I never got it. fed by the proverbial “piece of wet string”, the nominal 230V mains is set high at around 245V on light load and regularly varies between about 210V and 250V. On occasion it gets as low as 190V. I successfully deploy both small vintage “ferros” and a Variac servo regulator to supply my vintage test gear and receivers. We just accept the short household lamp (globe) life though. John Reid, Tauranga, NZ. Film-to-DVD conversion tricks I’m sorry that the article on transferring movies to DVD (April 2011) was not around five years ago when I needed it. I struggled with all sorts of electronic magic for timing but I suggest that your readers use DVD Infinity at North Sydney for easy and excellent results on mini-cassettes or DVDs. But this is the only the start of the problems. Older film has a nasty way of twisting, distorting and shrinking. If you look along it, it appears curved The second is that I’ve always dreamed of building a small, portable computer in the form factor of a portable game machine plus slide-out keyboard or PS2 socket and four USB ports. An SD or CF card slot would hide in the battery compartment (AA or C for long life). I think that if I built a “Maximite 2” with a NewHaven (from Jameco. com) parallel LCD and the 100-pin PIC32, then I am well on the way. This is a HUGE project for my background and help from others would absolutely be loved. Software-wise, my preference would be a characterbased menu system like the old QuickBASIC or free QBASIC. I just hope Maximite will be a blockbuster for us all. David Morton, Geeveston, Tas. siliconchip.com.au Why are hearing aids so expensive? crosswise. This means that as it crosses “the gate” in the projector, the centre is out of focus with the edges or viceversa. I suggest your readers contact “The Redcliffe Picture Palace” in Queensland for advice on their “Liquid Film Plasticiser”. This treatment may take 12 or more weeks but with it you will be able to get consistent focus. Then I suggest you send it off to DVD Infinity and you will be thrilled with the results. I got great results from a 1948 standard 8mm film that had been badly warped. Robert Armstrong, Toronto, NSW. I wonder why hearing aids are so expensive. In all other fields of electronic endeavour, costs have benefited through advancing technology but hearing aids seem to have missed out. For example, I bought the latest and best computer with LCD screen, with lots of software, as much memory as it would take, the largest hard drive available and a multifunction printer. The bill was $2349.01. About 19 months later, I bought two hearing aids, digital but not the most expensive, and they cost $2400, ie, $1200 each! On top of that there were three consultations and two new ear moulds; a total of $2740. There is a mystique that surrounds hearing aids which, after all, are quite simple devices compared with TV sets, computers, printers, cell phones, CD players and so on, despite the “clever” things that they can do. Production volumes are probably quite small compared with a lot of consumer electronics but if each $1200 hearing aid was made by hand by someone being paid say $50.00 Switching power supplies in DVD players have lots of EMI I recently bought a Sony DVD/CD player (model DVP-SR700H). This unit is a marvel of compactness and economy, typical of the inexpensive and compact DVD players now on the market. However, it radiated so much radio frequency “hash” that it completely obliterated broadcast-band reception in a nearby radio. The hash was even obtrusive in a radio in an adjacent room. Moreover, the hash was present even when the unit was not being used. Remembering Mauro Grassi’s article (SILICON CHIP, October 2007), I decided to build an old-fashioned external linear power supply. The internal circuit boards indicated a requirement for 15V and 5V supplies. I began us- ing 7815 and 7805 voltage regulators, along the general lines described in the article but to my surprise and disappointment, the unit refused to work. By a process of elimination I traced an hour, they would take 24 hours to make one aid. I doubt if this is how they are manufactured! I think that people with hearing loss are “being taken for a ride” This is accepted by “little old lady” type people and others who are only too glad to get the benefit of hearing aids no matter what the cost. In New Zealand there is a Government subsidy available but the aids should not be so expensive in the first place. Clive Singleton, Lower Hutt, NZ. Comment: you have already touched on some of the reasons why hearing aids are so much more expensive than typical consumer electronics products, most of which are massproduced in Asia rather than being made in relatively small quantities in high-labour cost countries. We suspect that a major part of the high cost of hearing aids which are supplied and fitted by an audiologist is due to the fact that they have to be individually fitted and programmed. There is now a much cheaper userprogrammable hearing aid available from Australia Hears (australia hears.com.au). We hope to do a review article on this in the near future. the problem to the 5V supply. Of course, I had no idea of the current required but the 7805 regulator can supply up to 1A. Surely this would be sufficient? But measurements with Digital Storage Oscilloscopes ADS1022C • 25MHz Bandwidth, 2Ch • 500MSa/s • USB Host & PictBridge $399 ADS1062CA • 60MHz Bandwidth, 2Ch $627 25MHz 60MHz Inc GST • 1GSa/s • USB Host & PictBridge Inc GST ADS1102CA • 100MHz Bandwidth, 2Ch • 1GSa/s 100MHz • USB Host & PictBridge $836 Inc GST For full spec sheets and to buy now online, visit 36 Years Quality Service siliconchip.com.au www.wiltronics.com.au Ph: (03) 5334 2513 Email: sales<at>wiltronics.com.au June 2011  5 Mailbag: continued More on in-wheel motors for electric cars I have just been reading letters to the editor in the April 0211 edition – in particular “Mitsubishi i-MiEV should have in-wheel motors” and saw your comment on connecting wheel motors in series and how does it let them run at different speeds around a corner, etc. Your correspondent is right! I built a small remote vehicle having two wheel motors (in my case small permanent magnet DC motors) connected in series to a single speed controller. It gives a pretty good analog to a mechanical differential. If you want accurate speed control you can even connect the tacho outputs in series and feed that into the tacho input of your speed conan external bench power supply show­ ed that the peak current required was a little over 1.5A, well beyond the capacity of the 7805 chip. I replaced it with an LM350K regulator, which is capable of delivering 5V at up to 3A. Surely that would fix the problem? But the unit still refused to work. The power was being delivered but no joy. What could be wrong? Finally, the penny dropped. More careful measurement showed that the original 5V switching power supply delivered 5.3V. As a general rule, the nominal 5V required by ICs is not very critical. I had assumed that 5.0V would suffice, but no. A simple adjustment to raise the troller. If you have full tachometric feed­back, the mechanical analog is almost exact. It is easy to demonstrate the boundary conditions of differential action. Hold the wheels off the ground and they both run at about the set speed. Stop one wheel and the other one spins at twice the set speed (just like a mechanical differential). In operation around a corner, the torque and speed of the two motors adjust to the differential speed requirements, just like a mechanical differential. It is impressive the first time you see it in action. Dr David Hainsworth, Mining Science & Engineering Program Leader, CSIRO Earth Science & Resource Engineering, Kenmore, Qld. output of the LM350K regulator to 5.4V solved the problem! The result – complete elimination of the hash, at a cost of about $100; about the same cost as the original player, plus the inconvenience of a bulky external power supply. The original unit is compact and economical but has cost-cutting been taken too far? Sony is a reputable brand and I had considered returning it under warranty but it was probably performing to specification. Not all devices with switching power supplies produce this much radiation. There seems to be a need for more rigorous standards for electromagnetic radiation from switching power supplies. More filtering and shielding should do the trick and the additional cost should be minimal. I can’t see us going back to linear power supplies. James Goding, Princes Hill, Vic. Comment: that you had to go the trouble of building a bulky external power supply highlights the fact that switchmode supplies in cheap DVD players are simply unsatisfactory. More to the point, it makes nonsense of any EMC standards or C-tick approvals. Cars with lights on high beam are dazzling I have a concern over motorists who are using their high-beam lights with no thought given to other road users. I do realise this can happen accidentally; maybe car manufacturers could install another switch which disables high beam to stop this situation. Sometimes I could swear that a vehicle approaching or behind me has the lights on high beam. This can be very dangerous in certain situations. Is there any way to meter another vehicle’s headlight to prove to yourself whether their high beam is on or not? If different headlight technologies give out different light levels then maybe this is a another problem or maybe trying to meter at night from a distance makes it unworkable. My other requirement is for an alarm for a fridge/freezer door when it is accidentally left ajar or open. This has happened twice to me just recently in hot weather while I was at work. So over the day I lost quite a bit of food and the poor old fridge was working very hard to no effect. I realise that un- Hakko FX888 Hakko FX951 Hakko FR803B General purpose soldering iron Advanced lead-free soldering iron Hot Air SMD Rework Station • • • • Compact Lead or lead-free solder Excellent thermal recovery With tip conical shape T18-B, cleaning sponge and wire • Heating element and tip in one • With sleep mode, auto shutdown, lock out card, quick tip replacement. Proudly distributed in Australia by HK Wentworth Pty Ltd 6  Silicon Chip • Digital station with 3 steps temp profiles • Vacuum pickup • Adjustable 100o-450oC • Optional stand, pre heater and vice www.hakko.com Ph: 02 9938 1566 sales<at>hkwentworth.com.au siliconchip.com.au siliconchip.com.au June 2011  7 More on memory size of flash drives In regards to your comments on memory size of storage devices (Ask SILICON CHIP, April 2011), whilst you’re quite correct concerning the blatantly spin-derived advertising figures that you talk about, you neglected to mention that the capacity reported is also a function of the file system used and block sizes the device is formatted in, as every file system is optimised differently. For example, a 500MB USB stick formatted with a FAT file system will return 515,612,672 bytes (using the default 8K block size) or about 491MB. When formatted with a FAT32 file system, it will return 514,854,912 bytes (using the default 4k block size) or about 492MB. When formatted with an NTFS file system, it will return 510,619,648 bytes (using the default 512-byte block size) or about 487MB. This discrepancy is more exaggerated in much larger devices. Jason Ditcham, Panton Hill,Vic. add to the glare problem. Second, keep mirrors dipped to minimise the chance of being blinded by a car at the rear. Third, if you wear glasses you should have them anti-glare coated – it does help. As far as your fridge is concerned, we featured a Fridge Door Alarm in the June 2004 issue. Having a hot shower is almost considered a crime Mailbag: continued less someone is home to hear the alarm, the device would be fairly useless. Any suggestions ? Mark Eastaugh, Armadale, WA. Comment: your letter raises a subject which is of interest to most readers, particularly those who are older. Night-time glare is exacerbated for older readers who have cataracts developing; everyone eventually suffers from cataracts. It is true that some drivers are ignorant (or deliberately rude) and do drive with lights on high beam when facing on-coming traffic and when following other cars. Some cars with HID headlights also seem to have more glare than they should and they can be painfully bright. They are probably not correctly aimed. You don’t really need a light meter to tell when a car has its headlights on high beam; if they’re dazzling they are probably on high beam. And if they are on high beam, there is nothing you can do about it. It is also true that cars with dirty headlights cause more glare than with clean headlight lenses, even when they are on low beam. There are no electronic solutions but there are several things you can do to help minimise the problem. The first is to keep the windscreen, rear window and all mirrors of your own car as clean as possible. Dirt and grime 8  Silicon Chip In your Publisher’s Letter in the April 2011 issue, you scoff at the statement, attributed to the “misguided government”, that “every time you have a hot shower powered by electricity, you’re using the same amount of energy that it takes to run 150 televisions at once”. What does that really mean and could it be true? Perhaps it suggests showering uses energy at the same rate as that which is required to run 150 television receivers. A “back-of-the-envelope” calculation confirms this, as follows: 150 TV receivers at (say) 200W each require 30kW of electrical power. If it is assumed that a shower uses 10 litres/minute (ie, 0.17L/s) of water which has been heated from 10°C to 55°C (a temperature rise of 45°C), and that the specific heat of water is 4.2kW/kg/K, then the power required is 0.17 x 4.2 x 45 = 32kW, which agrees quite closely with the consumption of the TV sets. Thus, although the government’s statement might have been rather more carefully worded, it is essentially true. What was not mentioned in your editorial however, and is at the very heart of the problem of using electrical energy for heating, is the fundamental practical limit on the efficiency of power stations in converting the energy in the original fossil fuel, be that coal, oil or gas, to electricity. This limitation is described numerically by the second law of thermodynamics and limits the maximum possible efficiency from such stations to about 30%. Thus the generation of electricity from combustion processes always results in about two thirds of the original calorific value of the fuel being wasted. That’s why using electricity for siliconchip.com.au bulk domestic water heating is almost a crime! Andrew Baghurst, Port Elliot, SA. Comment: the statement is still ridiculous and it is intended to make people feel guilty or as you say, “almost a crime”. For a start, no-one has a shower with a water temperature of 55°. It would be too hot. Even if we accept that, say, 18kW is being consumed while you run the shower, then this is an argument for having a shorter shower, not for replacing a perfectly functioning hot-water system. While you are correct in your assessment of using coal-fired electricity to heat water, it should also be remembered that most hot-water is heating is done at night when the generators are essentially on spinning reserve – they have to be run continuously in any case, whether water was being heated or not. 3-stage MPPT solar charge controller has minimal benefit I would like to comment on this siliconchip.com.au project, having just used it on a short camping holiday. While it is a nice 3-stage regulator, the MPPT feature is, as far as I am concerned, a waste of effort. Using an 80W panel and alternating it with a conventional regulator that has FET switching, the old style regulator almost always performed the same or slightly better. The MPPT circuit seems to use around 5W and when the battery voltage is above 13V, the MPPT regulator is no better than a straight connection. When I test the unit on a power supply feeding it with 17V, the output current is always higher than the input, suggesting that it is working properly. I might add that I have also owned a locally-made unit (the GSL 12A) and the results were much the same, the main advantage with the GSL being that you can use a 24V panel on a 12V battery without any adjustment. Horst Leykam, Dee Why, NSW. Comment: for an 80W panel, the maximum power point (MPPT) should be around 4.44A at 18V. For a direct connection from the panel to a 12V battery, the current would be around 4.6A at 12V and 4.55A at 14.8V, ie, 55.2W and 67.34W respectively. It is true that for smaller wattage solar panels the benefits of MPPT charging are diminished. That’s because the losses in the MPPT charger begin to match the extra power delivered compared to a direct connection to the battery. For the 80W panel, the result when the battery is at 14.8V would be around 75W with MPPT charging, assuming a 5W loss in the MPPT charger circuitry, compared to a 67W charge for the direct connection. At a battery voltage of 12V, the MPPT charger would be charging at 75W and the direct connection 55W. So the advantage is better when the battery is discharged. USB port for PC high-current bench supply conversion I found the article on converting an old computer power supply to a bench supply (SILICON CHIP, January 2011) to be very interesting and I’m just look- June 2011  9 Mailbag: continued ADSL Line Performance Helping to put you in Control Control Equipment Logbox-DA Datalogger with two input channels, one analog and one digital pulse. Able to store 64,000 readings and IP67 rating for water and dust protection. Great for monitoring water usage and flows. LOG-0031 $259.00+GST RFID Starter Kit Every- thing you need to get started with RFID. It includes a USB RFID board, ID-12 RFID reader, and 2 RFID cards. USB Serial output to a PC SFR-104 $49+GST Cyclic Timer Simple to use cyclic timer with programmable ON-OFF times. 1 shot or continuous. 6 timer ranges 0.6s100hr. HER-103 $59.95+GST GSM Alarm Unit The RTU5000 is a universal GSM alarm dialer and controller. It has 2 open collector outputs, 4 digital inputs (1 can be used as a 23 bit counter), 1 analog input and an RS-232 serial port. It allows you to monitor and control remote equipment. KPR-003 $249+GST AM822 Bipolar Stepper Motor Drive New fully digital drive for large stepper motors up to 5.9A and 80VDC. Microstepping and auto tuning for optimum torque. SMC-011 $179+GST Arduino and Ethernet Freetronics have released their new 100% compatible Arduino board with on board Ethernet and a mico SD card for web content storage or datalogging. FRA-005 $63.59+GST Ethernet Surge Protection with high response surge arresters TOD-022 $45.00+GST Contact Ocean Controls Ph: 03 9782 5882 www.oceancontrols.com.au 10  Silicon Chip Wiring Normal Cable Line measurements Average Actual line rate (kbps) 4357 4528 4450 4415 4437 Attainable line rate (kbps) 4780 4972 4852 4840 4861 Noise margin (db) 6.4 6.6 6.5 6.5 Attenuation (db) 54 54 54 54 4850 4675 4780 4855 4790 5292 5124 5220 5300 5234 6.3 6.1 6.4 6.3 6.3 54 54 54 54 54 Actual line rate (kbps) Crossover Attainable line rate (kbps) Cable Noise margin (db) Attenuation (db) Phone polarity and ADSL performance Your Phone Line Polarity Checker article made me wonder at first if I was reading the April edition of SILICON CHIP. Some of the points raised by David Drane appeared valid but I wasn’t too sure. Rather than building the checker I decided to experiment by connecting my Dynalink DSL modem to its central splitter/filter (and PSTN line) using a straight-through cable and then using a crossover cable. For each cable configuration the actual line rate, attainable line rate, noise ing into doing one for myself, along similar lines to that described in the article. While considering just how to do mine, I came to realise that there is an important feature missing from the one described in the magazine and that is a 5V USB port, so I’m going to add one to my unit. The way I am going to do this is to use an old USB add-on port that would have been connected to the motherboard and would have been fitted in one of the rear case slots. The port is attached to the backing plate with two screws. The port will be fitted in the power supply case and the two data wires will be cut off and the two power wires will simply be connected to the 5V power supply wiring, thus providing a 5V USB power port. I thought this idea could be suggested as an after-thought for the original project. Bruce Pierson, via email. margin and attenuation as reported by the modem was recorded after rebooting the modem. This was repeated four times. The results confirmed David’s article and showed approximately a 7% improvement of actual line rate; Not a big difference in the scheme of things but interesting that the line polarity does make a difference. My DSL service is at the end of a 3.5km line and I wonder what the results would be like closer to or further from the exchange? Stephen Wright, Wahroonga, NSW. Neck coupler could use telephone cable I have a couple of suggestions regarding the physical design of the Microphone to Neck Loop Coupler for Hearing Aids from the March 2011 issue. Construction of the loop is a bit awkward because the constructor has to make and insulate all those connections as shown in Fig 3. Also, since the loop is unbroken, the user will have to slip it over their head, which could mess up one’s hairdo. These problems can be eliminated by making the loop using 4-conductor telephone cable complete with a modular connector at each end. Put two modular sockets on the PCB. All the loop connections can then be made on the PCB. The user can then put the unit on or take it off by inserting or removing one of the modular connectors from its socket. The loop would then only need to be big enough to go around the neck rather than having to siliconchip.com.au be wide enough to go over the head and hair. In fact, only a single modular socket and plug are really needed and the other end of the loop cable can be soldered directly to the PCB. This would have the advantage that constructors could simply snip the desired length off one end of a pre-made telephone cable, without having to use a special tool to crimp a modular connector at the cut end. Further, if the loop could be made to work with just three conductors, the fourth conductor could be wired in series with the battery so that the unit is automatically turned off when one end of the loop is disconnected. Power switch S1 could be retained in case the user needs to turn the unit off without physically removing it. Andrew Partridge, Toowoomba East, Qld. Comment: this seems like a good idea. However, the smaller the loop the less effective is the coupling to the T-coil in the hearing aid. Also, if wired with three conductors and using the fourth conductor as the battery connection, the effectively shorted power loop may affect the signal loop performance. Feedback on phone polarity checker I read with interest the article on the Phone Line Polarity Checker (SILICON CHIP, May 2011 and decided to check out my new home. I made up a checker from loose parts and then found great difficulty in finding out which is pin 1 of the three RJ12 female sockets in my house. Nevertheless after much internet searching, I made the assumption that by looking at the socket with the locking/locating tab down facing, the connectors at the top would number left to right, ie, pin 1 to pin 6. Therefore, as you say, pin 4 should be positive with respect to pin 3 but it isn’t in my house. I then went to my modem (2-Wire 2017-A) set-up and noted that the settings there were: Downstream Rate = 11,423 kbps, Upstream Rate = 810kbps, Current Noise Margin = 12dB (Downstream) 12dB (Upstream), Current Attenuation = 39dB (DS) 21dB (US) and Current Output Power = 19dbm (DS) and 12 dbm (US). siliconchip.com.au So assuming the worst, I swapped the cable with a crossed cable to see what the change in polarity would do. But this had little effect as the settings were much the same. Hence it seems my modem doesn’t care about line polarity. In this exercise I managed to drag out of my box of tricks about half a dozen old Series 600 to RJ adapters, and found that they were not all the same pin-for-pin configuration, with some reversing the wiring. This shows that it is no wonder that some people are having issues with polarity. Brian Collath, Moss Vale, NSW. CIRCUIT BOARDS? For all your prototype requirements ... from budget … More on phone polarity and ADSL performance Wow – thanks for the Phone Line Polarity Checker! I have long suspected that my broadband connection was slower than it should be and had thought it was because we were near the distance limit from the exchange. With the Checker I was able to discover that the cable into my modem produced a red light and when replaced with another cable that produced a green light my internet speed was significantly faster. With faster broadband and the DAB+/FM Tuner playing magnificently in the corner, what more could a chap want? More great projects of course! Love the magazine – hope it never stops. As a postscript to my original email, further investigation has shown that the original phone cable to the modem was wired correctly and that the polarity reversal occurred in the phone line transient protector in the power board I am using. It just so happened that when I replaced the original cable the replacement phone cable was apparently not wired correctly resulting in a reversal of the polarity back to what it should have been! Anyway – I now have a green light at the important part of the cable train. David Hebblethwaite, Maleny, Qld. Phone polarity has no effect on ADSL I was mystified to read the article on the Phone Line Polarity Checker for ADSL in the May 2011 issue of SILICON Model 3000 … to fullyfeatured QCJ5 Quick Circuit allows you to make your own prototype circuit boards and perfectly machined panels. Shouldn’t there be one on your bench? Tel +61 2 9807 7081 satcam<at>satcam.com.au www.satcam.com.au June 2011  11 Mailbag: continued Mitsubishi i-MiEV and in-wheel motors Thanks for publishing my letter in the Mailbag pages of the April 2011 issue. Leo Simpson’s comments were as usual thought-provoking. However, they have led to me doing some more research on-line and coming up with some suggestions about solving the problems with my favourite “in wheel” motors. Firstly, almost all modern cars already have a lot of electronics on board so perhaps it would not be a great problem to modify the systems of accelerometers, etc to sense cornering and feed power to the motors appropriately. The ABS system basically does the opposite with the brakes already! All we have to do is to use the accelerometer information to control the PWM controller for each motor with some input from the steering system. My reading tells me that an elec- DYNE INDUSTRIES PTY LTD Now manufacturing the original ILP Unirange Toroidal Transformer - In stock from 15VA to 1000VA - Virtually anything made to order! - Transformers and Chokes with Ferrite, Powdered Iron GOSS and Metglas cores - Current & Potential Transformers DYNE Industries Pty Ltd Ph: (03) 9720 7233 Fax: (03) 9720 7551 email: sales<at>dyne.com.au web: www.dyne.com.au 12  Silicon Chip tric car designed by Michelin in France back in 2009, with in-wheel motors, claimed an unsprung weight of 35kg on the front wheels and 24kg on the rear. According to the same source, the “Clio” petrol car has an unsprung weight of 38kg. Unless my source is wrong, where is the problem? I must confess though that my estimate of power loss in the differential was far too high. In practice, a loss of 5% looks about right but the weight loss remains the same! So we may not be saving so much energy but we are saving many kilograms of vehicle weight which can be used for increased battery storage. Many of your correspondents in the same issue are obviously Jeremy Clarkson fans, (don’t tell my wife – she can’t stand him) but very sorry folks, soon your V8s and V12s are not going to have any more fuel or you’ll be fighting continuous wars over what’s left. As Bob Heinlein said “Natural laws have no pity”. Is anyone prepared to give some thought to a suitable motor control system? Clifford Wright, Helensville. NZ. CHIP. I was unaware that line polarity had any effect on DSL operation or data speed transmission. It is a requirement that all customer equipment connected to the Australian PSTN must function as intended regardless of line polarity – see www. commsalliance.com.au/__data/assets/ pdf_file/0012/2505/S041_2005r.pdf and www.telstra.com.au/adsl/docs/ adslcpe.pdf (para 5.6.3). The telephone line is a balanced signalling line with the positive leg of the line single point earthed at the exchange end only. If a DSL modem/ router experiences data rate degradation when the line is reversed then the modem itself is the problem, not the phone line. The fact that there is 48V DC on the line should not affect the performance of the DSL equipment no matter in which direction any DC current is flowing in the DSL interface arrangement. I agree that there is a possibility that practice and theory will not always agree. However, apart from a few references in forums on the web (having relevance to the Australian PSTN), the issue of line polarity and ADSL performance hardly rates a mention. I would have thought that if line polarity were a problem, as claimed in the SILICON CHIP article, there would be numerous mentions, reports and warnings. I can’t even find any confirmed reports of problems when searching the web for any part of the world; quite the opposite in fact. In this forum http://forum.kitz. co.uk/index.php?topic=999.0;wap2 Setecio tried reversing the line and found no difference in data transmission speed. I have a friend who until recently worked on providing ADSL services for Visionstream and he is adamant that polarity is not an issue. He even says that ADSL will get through even if one leg of the line is open-circuit. Fig.4 in this article http://www. eetasia.com/ARTICLES/2000FEB/ 2000FEB01_NTEK_TA.PDF shows a typical ADSL full duplex transceiver (and that is 10 years old) and it can be seen that as far as the telephone line polarity is concerned (T & R connections) it will make absolutely no difference which way around the line is connected. DMT signals used by ADSL are not affected by line polarity since there is no DC current in the hybrid interface transformer/s. Without wishing to be flippant, I challenge you to find any confirmed reports where polarity alone has been the cause of poor ADSL transmission speed. I guess your time is too important to waste and it is of little importance in the grand scheme of things anyway. Who cares if SILICON CHIP readers actually believe that line polarity is a problem? At least they may go out and buy a kit to build the checker. Ross Herbert, Carine, Qld Comment: we can vouch for the fact that ADSL can get through when one line is open-circuit; two SILICON CHIP staff have recently had ADSL working while their phones were out of order. But it also appears that phone line polarity can affect performance. SC siliconchip.com.au Is your hip-pocket nerve hurting? We know how you feel – prices seem to be going up all the time. But you can save money by taking out a SILICON CHIP subscription. A 12-month subscription will get you 12 issues for the price of less than 11! For an even bigger discount, a 2-year subscription gets you 24 issues for the price of 20! Better still, a 2-year subscription gives you longer protection against price rises in the future. Count the advantages: q  q  q  q  q  It's cheaper – you $ave money! It's delivered right to your mail box! You can always be sure you'll receive it!! We pick up all the postage and handling charges!!! You will never miss an issue because it's sold out (or you forgot)!!!! $5200 6 months SILICON chip : 12 months SILICON chip : $9750 24 months SILICON chip : $18800 *These prices and comparisons refer to Australian subscriptions. Other countries are subject to exchange rates – please see page 95 of this issue. siliconchip.com.au June 2011  13 At last! An Energy Saving Device that ACTUALLY DOES save energy! by ROSS TESTER During the past few years, SILICON CHIP has exposed some decidedly “shonky” power-saving devices. So it gives us great pleasure in “exposing” another power-saving device . . . one that actually lives up to its claims. The FutureWave Energy Saver WILL save energy and siliconchip.com.au 14  Silicon Chip therefore money. And we have the test figures to prove it. W e first saw this device on one of the tabloid TV shows late last year. Typical of these shows, the report was full of “gee whiz” and short on substance. We wondered if the claims being made were real . . . or was it just another in the long line of power saving devices which don’t quite stand up to a technically-sound examination. Developed by a couple of electric motor rewinders in a shed on Queensland’s Sunshine Coast, the FutureWave Energy Saver was claimed to reduce electricity consumption by a rather significant amount. They claim up to 80% – a figure we can’t quite replicate – but the savings we can measure are not too far away. But we are getting a bit ahead of ourselves. Shortly after we saw it on TV, we tried to contact FutureWave via their website and emails – without a lot of luck. It turns out at the time they were simply too busy trying to keep up with demand following their TV exposure to have even more media exposure – which could further increase demand. But we persevered, eventually tracking down a mobile phone number which was not only answered but we were promised that someone would get back to us within a week or two. It was explained to us that FutureWave had moved to new premises and significantly ramped up their production capacity, so now they were happy to talk to the technical media which would put their device under much more scrutiny than the TV programs had. They were well aware of SILICON CHIP (in fact they subscribed) – so were also well aware of the damning reports we had published on previous “energy saving” devices. More to the point, they completely agreed with us! But they were also very quick to point out that the FutureWave device went about its energy saving task in a completely different, scientifically proven way (more on that anon) and it was also specifically intended for certain electric motors, the main target market being swimming pool and spa pumps. They were confident that FutureWave Energy Saver would stand up to SILICON CHIP’s scrutiny and measurements. In due course, a FutureWave Energy Saver was delivered to the SILICON CHIP office. Yours truly was given the task of reviewing the device, mainly because I happen to be the only one with a swimming pool in the back yard! The FutureWave Energy Saver It’s housed in an ABS box measuring 390 x 300 x 150mm. The lid of the box is clear and hinged, opening to allow access to a limited range of user controls. There are two large 3-position switches, one of which selects the mode of operation – full power (used, for example, when backwashing a filter), energy saving (ie, controlled by the unit) and off. The second switch selects the amount of energy saving – high, medium or low. There’s also a small knob which appears to vary the amount of time the FutureWave remains in its various modes, along with a couple of small pushbuttons which, while labelled “run“ and “start/stop“, have uses which were not immediately obvious. Perhaps these are explained in the operation manual which, unfortunately, our test unit did not come with. Above these controls is a LED display which gives a readout of the pump supply frequency, which varies acsiliconchip.com.au User controls on the FutureWave Energy Saver are minimal: two large switches controlling mode and energy saving level. Without instructions, we were unable to work out the controls at the top but the LED display reads the frequency supplied to the pump motor. cording to the energy saving setting. There’s a 230V AC mains input cable and, on the underside, a 230V AC mains socket, into which your pool pump plugs. And that’s just about it as far as the user is concerned. How it works The FutureWave Energy Saver is based on the assumption that the vast majority of pool pumps are more powerful than they need be for proper filtering of the water. There is a very good reason for this – no pool pump is used continuously (apart from wearing the bearings out, the cost of electricity would be prohibitive). But the pump almost invariably needs more “grunt” whenever it is started to overcome the initial resistance of the filter and getting the water flowing through it. The amount of power needed depends to a large degree on the type of filter. But once operating, the pump doesn’t need to keep pushing that amount of water through the filter – in fact, there is some argument to suggest filtration is better with the water flow just enough to pass through the filter medium. FutureWave themselves have published several field tests, both in large public and smaller private pools, which show no deleterious effects in pool water quality by using their device with lower flow rates. So what we normally have is a powerful pump pushing too much water through a filter; a pump that uses a quite June 2011  15 The FutureWave Energy Saver is perfectly suited to do-it-yourself installation. There is no plumbing or wiring to install: all you do is unplug your pool pump from its mains socket, plug it into the FutureWave and then plug the FutureWave back into the mains socket. If (as would be the norm) your pool pump operates via a time switch, the FutureWave plugs into it. Installation complete! significant amount of power at start-up, then continues to gobble power as it runs at too fast a speed. noise and (if it is important to you), your carbon footprint. That’s what the FutureWave Energy Saver promises. How much power? But does it deliver – and if so, how? A typical pool pump for a 50-70,000 litre pool (ie, a reasonable-size backyard pool) would be rated at about 1kW (~1.3hp). If the pump is run for a typical five hours per day during the swim season (depending on location, say 7-8 months, more with heating) that could be as much as 1000 x 5 = 5kWh x 265(days) = ~1250kWh. Add to that the pump/filter use during the off-season (most pool owners would drop it to about 1-2 hours per day) and you could add another 180kWh, or about 1430kWh for the year. At the current (at time of writing - see www.energyaustralia. According to FutureWave Energy Solutions, the Australian developers of the FutureWave Energy Saver (they’re based on the Sunshine Coast of Qld), this is how: “The Future Wave Energy Saver will soft start the pump motor, removing the huge initial start up demand of electricity. This start up process will take about 20 seconds to initiate. The pump will then operate at close to its normal rate for another 20 seconds while it primes the pump. When the pump is fully primed there is no need for it to draw so much energy to work effectively so the Future Wave Energy Saver will then wind the motor down to the energy saving level selected, saving significant amounts of electricity.” That’s an interesting comment: “wind the motor down”. The way it does this is the basis of the system. The FutureWave Energy Saver is, quite simply, a variablefrequency motor drive. In fact, the device is based on a purpose-designed VFD (a SV02iC5-1 module, made by LS Industrial Solutions of Korea). This module will handle up to 2.2kW (3hp) motors so the FutureWave is capable of handling the largest domestic pool and is, in fact, now being used at quite a few large community pools. Incidentally, according to specs we found on the ’net, this particular LS VFD module can also be used com.au/State/NSW/Residential/Products-and-services/Electricity/~/ media/Files/Residential/Pricing/2010/NSW_RES_PL.ashx) electric- ity rate of about 28c/kwh, your pool pump alone is currently costing you about $400 per annum. (Remember the high usage of a pool pump is likely to push you into the highest “balance per quarter” rate which cuts in at 1750kWh/ quarter). Even at the sub-1750kWh rate (~19c/kWh) you’re still up for the best part of $300 per annum. And that’s before the looming electricity price hikes (~18%?) – and, if it ever happens, a carbon dioxide tax. Wouldn’t it be nice to cut that down by half, or even three quarters? And at the same time, save in pump wear and tear, The FutureWave Energy Saver is based on a Variable Frequency Driver (VFD) which has an H-Bridge output to drive the induction motor at reduced speeds. In effect, the VFD switches the H-Bridge output devices (Mosfets or IGBTs) with a high frequency variable pulse width signal to synthesise a low frequency sinewave (more or less) at 50Hz (full power), 38.5Hz (low saving), 35.5Hz (med saving) or 31.5Hz (high saving). These scope waveforms show the actual signal delivered to the motor and as you can see, there is a considerable high frequency component still present. This does not affect the motor’s behaviour but it can cause AM radio interference (depending on the signal strength in your area). 16  Silicon Chip siliconchip.com.au Inside the FutureWave Energy Saver, with the front panel “folded back” 90°. The large module at the top is the Variable Frequency Drive (VFD) module which is the heart of the system. The large silver EMI suppressor (behind the switches) and the two toroid rings through which the power lines pass (all highlighted with arrows) should be capable of minimising radio frequency interference. They don’t work real well in low signal areas! to convert single-phase AC to three-phase (but of course, this feature is not used in the FutureWave application). As you no doubt know, the speed of an AC induction motor is “locked” to the mains frequency – in our case, 50Hz. Ergo, if you vary the frequency, you vary the speed of the motor. As long as you continue to supply sufficient voltage to keep the motor spinning, it will happily run at the lower speed. In a nutshell, this is what the FutureWave Energy Saver does – it varies the supply frequency. The clever bit, at least as far as we are concerned, is in the programming – what length of time do the various modes keep running and of course, at what frequencies. Table 1 below shows the theoretical rotational shaft speed of a (typical) 2-pole induction motor at various frequencies. Note that this is theoretical – for a number of reasons, to do with slip and load, the actual speed of the motor will be less than this. Typical 50Hz 2-pole pool pump motors, for example, will have a nameplate rating of about 28002850rpm, or about 5% less than the synchronous speed. So where does the power saving come in? It’s quite simple, really: run a motor at its normal (rated) speed and it uses maximum power. Maximum power equals maximum energy cost. Slow the motor down and, as long as it can continue to do the work required, the power (and therefore energy cost) decreases. There does comes a point, however, where the motor will start getting rather cranky at running too slow. Heat siliconchip.com.au dissipation from the windings can become a major problem (most induction motors have fans built in to assist in cooling), as does actually being able to supply enough “grunt” to run the pump or whatever device the motor is turning. Soft-starting the motor Another thing that the FutureWave does is “soft start” the motor. A rule-of-thumb is that starting current of an induction motor is around 500% of run current. This only lasts for a short time (perhaps half a second or so) until the motor is up to speed but in this time there is obviously a lot more power being used. By preventing this huge current at Frequency (Hz) 50 40 30 20 10 Shaft rotational speed (rpm) 3000 2400 1800 1200 600 Table 1: Synchronous motor speed versus frequency June 2011  17 These two scope waveforms are taken at a much higher sweep speed (200us/div) than those overleaf to illustrate the variable pulse width of the synthesised motor waveform. The waveform with the high pulse duty cycle is delivered on positive excursions of the waveform while the low pulse duty cycle is equivalent to the negative duty cycle. start-up, you’re going to save money. Incremental savings, perhaps – but they all add up! Wear and tear Running a pool pump for several hours means it will get rather hot. You only have to see the large fins on most pumps to see that efforts are made to get rid of this heat. It’s the pump bearings which normally wear out first and if left unattended, or unnoticed, may cause the motor to seize, overheat and ultimately burn out. Running the motor slower will result in cooler bearings, which in turn will result in longer bearing (and therefore motor) life. Our testing We did two different sets of tests – one in our laboratory, where we were able to capture the scope waveforms shown here, while the second was done “in the field” using a real pool pump on a real pool. The lab tests showed the unit worked and did exactly what it was supposed to. But there was a real sting in the tail – it was very difficult indeed to sync the scope on the waveform due to the large amount of noise on the waveform. The screen grabs show what we are talking about. Our lab tests also showed that the voltage delivered to the pump was also reduced, along with the frequency. While nothing like a sine wave, we were able to get the scope to give us “RMS” voltage readings for the three different settings. These are reproduced below with the consumption readings. Our “real world” test setup was quite simple: we used a 1.3hp pump already installed on a 50,000 litre pool. In line with the 230V power outlet (ie, before the pump) we placed a SILICON CHIP Energy Meter (see July 2004 issue) which gives an instantaneous reading in watts plus a cumulative reading in watt-hours (or kilowatt hours). We then ran the pump “as is” for two hours, then five hours. The two different periods were to not only ensure statistical accuracy; the higher run time is typical for a domestic pool in summer and the lower typical for winter use. These two readings were entirely consistent with what we would expect: 18  Silicon Chip Full power: 2 hours - 1.964kWh   5 hours - 4.953kWh (Power reading after “settling down” 1.01kW) Then we placed the FutureWave Energy Saver in line and repeated the tests, with the energy saving level set to all three positions in turn (via the switch on the front panel of the unit). Remember, the “high” position is actually the highest energy saving, or in fact the lowest power setting. As we mentioned earlier, we weren’t able to duplicate the 80% power savings claimed by FutureWave Technologies. But we were able to demonstrate quite significant savings, more than enough to justify the claim of an “energy saving device”: High: 2 hours - 675Wh 5 hours - 1.7kWh (Power reading after “settling down” 353W) Frequency: 31.5Hz Pump voltage: 122V (RMS) That’s a 66% reduction in power and is almost the same percentage reduction for both 2 hours and 5 hours, again as we would expect. As we said, not 80% but certainly getting up there and certainly worthwhile. We repeated the tests with the FutureWave set to medium and low energy saving levels and the results were, of course, not as good but good nevertheless: Medium: 2 hours - 975Wh, 5 hours - 2.42kWh (Power reading after “settling down” 486W) Frequency 35.5Hz Pump voltage:  140V (RMS) Low: 2 hours - 1.15kWh, 5 hours - 2.74kWh (Power reading after “settling down” 575W) Frequency: 38.5Hz Pump voltage: 161V (RMS) One point to note: running the pump through the FutureWave set to “Full Power” consumed 55W more than running the pump direct from the mains, so this is the FutureWave’s “overhead” and also should be taken into account when calculating power savings. Of course, running the system through a mains time switch would mean no overhead for siliconchip.com.au FutureWave comments . . . SILICON CHIP provided a copy of the review to FutureWave prior to publication, for any comment. Rather than amend the original article, we decided to publish their response verbatim for readers to consider. Here’s what they had to say: Hi Ross, Thank you very much for forwarding the article. We were very glad to see that the Future Wave Energy Saver performed as expected when running on a smaller 1HP (0.75kW) pump such as your pool pump Ross. From our perspective we would like the opportunity to provide some feedback regarding some of the comments and findings in the article. 1. Firstly to clarify the structure of the companies – The inventors/developers & manufacturing side of things is through ‘Future Wave Innovations Pty Ltd’. Our company ‘Future Wave Energy Solutions Australia Pty Ltd’ work direct with the manufacturers as the client facing sales side. Currently there are only a few smaller Re-Sellers out there but within the next few months there will be a proper robust Distribution Network put in place with a view to rolling out a nationwide accredited Reseller Network. So, just clarifying, we (Future Wave Energy Solutions Australia Pty Ltd) should not be referred to as the ‘Developers’. 2. I wasn’t made aware that the Future Wave had turned up without an instruction manual and had we been made aware of this we would definitely have provided one immediately. I have attached a soft copy of the information and instructions that are included with every Future Wave. The Future Wave that was redirected to Silicon Chip was one that was already sent to a customer in Sydney to trial and instead of sending it back to us in Queensland we thought it easier to have it sent on. Obviously they did not send it with the provided instructions etc. The buttons and dial that is referred to in the article are only used for the initial programming of the Future Wave after which they are programmed out so that no tampering can occur. In some ‘Custom’ cases the ‘Medium’ setting on the energy saving dial may be programmed to be variable and then the dial on the VSD would be used to adjust the frequency of the unit with Maximum and Minimum parameters set so the user can’t inadvertantly do any damage. 3. The article makes comment on the claims of ‘up to 80% savings’ but the Silicon Chips test results showed results in the high 60’s. This should be clarified that when we refer to ‘up to 80%’ it obviously means only in some cases. Results will vary for every pump depending on the size of the pump, load, make, model, age of the pump etc. The higher saving results are normally seen on larger pumps (1.5kW-2.2kW) and typically when running smaller pumps like the one tested (0.75kW – 1.0kW), we typically see closer to the 70% savings on average when running on the ‘High’ energy saving level. So we would say that your trial performed as we would have expected. 4. When referring to ‘typical pool pump size’ I think it is dangerous to say that for a 50,000 litre pool that a 1kW pump would be the norm. Pool pump sizes vary considerably depending on many factors, volume of water, filter design, complexity of the hydraulics, required turnover rates, climate, type of cleaner and so on. If I was having a guess for our climate in S-E Queensland and what would be typical, I would be estimating closer to a 1.5kW (2HP) pump would be the norm and a lot closer to what we generally see when selling or installing the Future Wave. Smaller pools under 50,000 thousand litres would typically utilise smaller pumps as you mentioned. Also the reference to ‘typical five hours per day for the swim season’ as the general amount of time that an average pool pump would run also should be questioned. For a 50-70,000 litre pool through a warm to hot summer and the pool being frequently used, five hours would be dangerously close to the bare minimum that it should be running. Once again depending on many variables, pool size, pump size, climate, exposure, usage, type of filter, type of chlorinator, plumbing design etc. etc. this will vary considerably. I think you will find that generally any pool designer or pool maintenance professional will recommend running your pool for up to eight hours for water quality and hygiene purposes, especially on a 50-70,000 litre pool. The further reference of ‘1-2 hours run time in the off-season’ would be a very small minority of pool owners. There are over 500,000 pool owners in Queensland alone and the vast majority of these pool owners would be running their pool pumps for 3-5 hours at minimum throughout our small off-season, with a lot of pools now having solar water heating you will more than likely find that pools are being used year round and the pumps would be still running closer to 6-8 hours. 5. Point 4 above will obviously have an impact on ‘typical savings’. You refer to a payback term of two years through savings. Once again this will not be the case for everyone but in some cases we frequently see payback periods under two years. This will obviously be when pool owners have larger pumps than the one you tested and they run for more hours a day. I think we should make it clear that with your test scenario used of two hours run time in winter and five hours in Summer on a smaller pump of 1kW we would not expect to see a two year ROI. On larger pools running larger pumps and running for eight hours or more a day then you will obviously see much better savings and payback periods. A fairly typical pool pump in Queensland of 1.5kW running eight hours a day on peak tariff of $0.2135per/kWh would be $233.00 per Quarter or $932.00 a year. At 70% savings this would mean a $653.00 saving per annum. At the price of $1295.00 this equates to pretty close to a two year payback period even if electricity prices were not to increase, but we all know this is not going to be the case and we will expect to see some pretty hefty increases meaning higher savings and a better payback period again. 6. Your findings of AM interference is a known issue and that is accepted but with thousands of units being currently used we are only aware of maybe a couple of individual instances that this has been an issue. The Future Wave Energy Saver passes all relevant Australian EMC standards and compliances. Further testing and development is being carried out with a view to address this concern. In individual cases where this is an issue we are happy to work with the customer to have it resolved. The quoted comment of ‘no-one listens to AM anymore’ is obviously used out of context and should be removed as I was the person who light-heartedly made that comment and I was quick to acknowledge that it was a known concern and that the designers were working on a fix and that I would take the findings directly to the designers to make comment on. We have been more than accommodating with giving Silicon Chip ‘free reign’ with their access to the Future Wave Energy Saver and ability to test it along with being available for comment and feedback and we think that this comment and the context of the paragraph makes us sound arrogant and dismissive of the issue which we clearly are not. Overall we are obviously very happy that the unit tested well and the results are mostly positive but we would greatly appreciate the above comments be given consideration. Kind regards, Charlie Notting Future Wave Energy Solutions Australia Pty Ltd siliconchip.com.au JJune une 2011  19 most of the time (ie, whenever it is off, it is OFF!). Power cost Let’s translate that energy usage into the language everyone understands – dollars – using the same rates we used earlier. Again, we are using the “high” setting. 1.7kWh per day times 265 days (summer) times $0.28; plus 675Wh times 100 days (winter) times $0.28, brings your annual pool power bill down to just $145.00. The lower energy usage may well keep you under the 1750kWh “premium rate” so you could even be paying around $98 per annum. What were those “full rate” figures we quoted earlier? Hmm: $400 and $300! Noise Here there is good news and bad news. The good news is very good and the bad news is, at least in my case, awful! First of all, let me say that my pump is about five years old so by this time, you might expect quite a bit of bearing noise. Such is definitely the case: with the pump running on full power, we measured it at 79dBA <at> 1m and 65dBA <at> 5m, against a Sunday morning background level of 47dBA. That’s loud enough to be quite noticeable during the day but it’s unacceptably loud during the still of the night. In fact, many councils have ordinances which prevent pool pumps being run after 9 or 10pm or before 6am – a time when many people on “smart meters” would prefer to run them to take advantage of significantly lower tariffs. The good news With the FutureWave Energy Saver in line and operating at its best saving rate, the noise level dropped to a much more satisfactory 72dBA <at> 1m and 57dBA <at> 5m. That’s probably still too loud for night-time operation although, with a newer pump, it would obviously be significantly lower again. A modicum of sound-proofing around the pump may be all that is required. On the mid and low settings, noise was (respectively) 74dB/76dB <at> 1m and 58dB/60dB <at> 5m. The bad news If you like to listen to AM radio and you don’t live in a relatively strong signal area, forget about using the FutureWave Energy Saver (at least as it is currently configured). Let me explain that: while I’m only about 20km from the centre of Sydney, radio and TV signal levels at my place are renowned to be low, mainly due to topography. I would equate the level of signal as akin to that of a country town, where the “local” radio transmitter can be many kilometres away; perhaps even several towns away (and may be fairly low power into the bargain). My pool pump is virtually on the back boundary of my property (a standard 15 x 45m suburban block). My house is set well forward on the block. No AM radio reception was possible anywhere in the house or yard when the FutureWave was turned on – in fact, my partner has never moved so fast, to turn any radios off when that “damnawful noise” started! I’m not simply talking about mains-powered radios where the interference could have been introduced via the mains wiring. I’m also talking about interference on a battery powered portable, not just on my property but right across the road – a distance of about 65 metres from the offending noise source! I wasn’t game to ask my next-door neighbours if they had the same problems as I (they’d know who to blame!) but 20  Silicon Chip clearly if I was having reception problems at 65m, the odds were pretty good (or is that pretty bad?)! The FutureWave does have EMI suppression built in, as our photo clearly shows. However, it just as clearly is inadequate if your AM radio reception is not strong. I mentioned this problem to FutureWave after my tests and they were aware of the problem but were, if not dismissive of it, didn’t think it too big a problem. Their comment: “no-one listens to AM radio any more . . .” I’ve got to tell them that this little black duck does, as do many friends and colleagues. They did say that the designers were aware of the interference problem and were working on a “fix”. I hope for their sake the fix is quick – otherwise I suspect that many users, especially in country areas will say “bugger the savings – I want my radio reception back.” How much? It’s not easy to get a price for the FutureWave Energy Saver. Everyone wants you to contact them and they will get a “representative to contact you” who will then tell you the price. Perhaps the reason for this is that it is sold through a variety of on-sellers who may wish to provide extra services at installation (particularly if they are pool shops, etc). But the FutureWave Energy Saver doesn’t need “installation” as such – it is quite suitable for the do-it-yourselfer to put in (how hard is it to unplug the pump power lead and plug it back in via the FutureWave?). So many readers may want a “supply only” price, as distinct from a “supply and install”. We believe the “supply only” price is around $1295.00 – at least, that’s the only price we could find on the ’net (there were plenty of suppliers offering the FutureWave but with only one exception that we could find, all remained pretty coy about how much it cost. Most simply claimed that you would save the cost back in two years, or words the that effect). Incidentally, we have a bit of a problem with that particular claim. As we noted earlier, two years at full electricity tariff is about $800; our measurements suggest two years with the FutureWave is at best about $180. The difference is a bit over $600 – a fair way short of the $1295 FutureWave cost. Four years? Now that’s a different proposition. Conclusion OK, the FutureWave Energy Saver clearly works and will clearly save energy. With electricity prices slated to increase yet again this month, that saving can only be a good thing and will reduce the payback period of the unit. Just how much you save also depends on which setting you run the FutureWave on, the length of time you run it (eg, does it keep the pool clean?) and whether or not you can take advantage of lowest electricity tariffs. If all your ducks line up, the savings can be quite significant. However, until that interference problem is fixed, anyone with a FutureWave, especially in the country but even city dwellers who don’t have strong radio signal levels, may well run into AM radio reception problems – if not themselves, with neighbours up to three houses or more away. SC For more information on the FutureWave Energy Saver, and a list of suppliers, visit the company website, www.futurewaveenergy.com.au, or call Futurewave Energy Solutions Australia on 1300 979303. Postal address: PO Box 577, Mooloolaba, Qld. 4557 siliconchip.com.au e r o t s SOLAR ENERGY.com.au THE SMART CHOICE Solar Power BACKPACK Charge your iPhone, camera etc, while you walk. Complete set ready to use $49 NOW ONLY $35 LED 12vdc Bright Lights Great for camping tent, caravan etc.5m Roll easily cuts to size. Waterproof + adhesive back fast easy installed. Silent Sine Wave Generator Battery Charge Controller INFOMON COOLING FRIDGE - FREEZER Protect your battery from overcharging. PLUS: LCD display shows you the amount of power you are using and producing. Also lets you know battery VDC and Batt capacity Pecentage. 240VAC Power, 4.4KVA: $799 2kVA also available: $499 From $89 Solar Panels BEST PRICES IN AUSTRALIA! 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Micro Computer Temp Control energy saving system so it does not stress out your batteries. 45L was $1499 NOW $ 769 60L was $1699 NOW $799 80L was $1899 NOW $899 FREE BONUS : Insulation Cover, Wall charger and cigarette adaptor. NOW $499 For those who want to generate some serious power we have a 1000 watt system complete kit with stand and controller Dont Pay over $2000 SALE $1199 LIMITED STOCK Heavy Duty Diesel Was $2000 NOW $899 siliconchip.com.au June 2011  21 5/110 Station Rd, Seven Hills NSW 2147 (Mon-Fri 9am-5pm) Phone (02) 9620 9011 www.lhp.net.au Not long ago, Queensland endured some of the worst flooding on record. During this time I was offered the opportunity to recover some radio receivers that would otherwise have ended up as landfill. SALVAGING ELECTRONICS AFTER THE FLOOD T he equipment concerned was ex-Army communication receivers, Rohde and Schwarz ESMC 0.5-650MHz, about fifteen years old. The receivers were stored in a shed that that went to the roof in floodwater and remained so for a day or two. The owner had picked them up at auction and was in the process of selling them on a popular internet auction site. Electronics gear, especially the older stuff, is like artwork – its beauty is in the eye of the beholder. Where some would have turfed these straight on the scrap heap, the magpie nature in me couldn’t resist a challenge. Rohde and Schwarz equipment is well built and has a good name, so I picked up six of the better looking units to take home and repair. The rest were consigned to the pile of ruined memories on the footpath outside, like the contents of so many other flood-affected houses in our area. If you are going to try this sort of flood recovery of electronic equipment you need to pick your targets. Some things, like speakers and gear 22  Silicon Chip with non-removable batteries can be a lost cause. As with most flood events, the effects on equipment change with many different factors. Floodwater might be clean, like rainwater runoff or a broken pipe; the flood event may only last a few minutes or even seconds. In this flood, the water was brown, silt-laden (and who knows what else) and lasted a day or two, the water backing up a small creek that led to the local river. The longer gear is submerged in the flood water, the more it will accumulate silt and muck. The last local flood of this calibre was in 1974 and most places were flooded for a week or more. After that length of time immersed in flood water, equipment recovery gets very difficult. Each situation requires its own assessment as to the worthiness of an attempted recovery and special consideration needs to be given to high voltage and mains-powered gear. Never try to power up electrical by Robert Googe equipment that has come in contact with water until it has been fully checked by a suitably experienced person. And remember your personal hygiene: flood water can contain all sorts of contaminants, from industrial chemicals to raw sewage. If you are at all suspicious about any contaminants, use gloves and wash your hands! Even a face mask might not go astray. Having never really attempted flood recovery before, it was time to sit down and have a think about how to go about this. More speed, less haste! Time is the enemy but I had other commitments for a few days and could not begin the rescue process straight away. So the first thing I did was take freely available oxygen out of the equation – the less oxygen available, the slower the corrosion process. How would I do that? Well, counterintuitive as it may seem, I drowned the equipment/gear again. I figured that if I could cover the receivers with clean and (almost) ionfree water from our rainwater tank, I siliconchip.com.au Just as they were about to be auctioned off on the internet, the once-in-a-lifetime flood decided to wreak its havoc (for the second time this lifetime!). Some of these Rohde and Schwartz receivers were consigned to the scrap heap . . . but I couldn’t resist having a go at trying to clean some of them up and get them going! could achieve several things; give the gear/equipment a good flush of clean water, removing some of the silt and reducing the oxygen availability that would have been higher in air. Initially I was stumped as to how I was going to achieve this, as these units aren’t exactly on the small side, about as big as a size 13 shoe box (yes, I should know!). Something large enough to completely submerge them, obviously water tight . . . Then it hit me, a wheelie bin! So the contents of our recycling bin went onto the ground, the receivers were stacked up inside and the bin was filled with water from the tank. Check for batteries! It was just as I finished filling the bin, I realised there was something I needed to do. The first thing I should have done was to check for batteries and disable or, preferably, remove them. Batteries in water accelerate corrosion by electrolysis, so removing them is essential. That’s why so many “I-xxx” devices made by that fruit company (as Forrest Gump called siliconchip.com.au it) do not survive immersion – the (non-removable) battery voltage kills circuitry by corroding, or by the voltage being in places it shouldn’t thanks to moisture. Quickly pulling apart one of the units, I found there was a rechargeable Nicad backup battery on the processor board. I did not have time to remove each battery but it was a simple move of a jumper to take it out of circuit. This was done for each unit. The other enemy is bi-metallic corrosion. This is where two dissimilar metals can set up an ion flow due to their atomic structure; water in this case can promote this process. Thankfully, this did not present a problem in this case, probably because I was using tank (and therefore quite pure) water. Documenation Documentation is another issue – the more the better. Unfortunately for specialised gear such as this (and even more so as it is ex-military), there’s very little (read: no!) information freely available on the Internet. Thank- Even after rinsing in fresh (tank) water, there was significant evidence of the flood inside. This pic isn’t of corrosion or dust due to age, it’s good old Brisbane River mud. Further inside, I found quite a bit of the Brisbane River itself! June 2011  23 Once again, I was surprised at the lack of “damage” when I opened the lid after the big rinse. But delving down revealed a liberal coating of dirt and, in some cases, captured areas of water. All of these required thorough cleaning/drying and testing before there was even a thought of reapplying power. fully the original owner could give me an electronic copy of the operation manual which did have a short section on troubleshooting. This included a few steps on narrowing down any issues and outlined supply voltages etc. A logical order Two days later I finally had the time to take the next step and strip one of these units. After some thought, I decided on the following procedure: • Strip each board, removing covers, RF shielding, etc. • Wash each part in a tub of water with a toothbrush/paintbrush/rag. • Rinse in rainwater. • Spray liberally with methylated spirits (metho). • Gently blow excess fluid off with compressed air. • Suitably label the dismantled components. • Leave in the hot Queensland sun to dry (we were actually getting some by that stage!) The methylated spirits act as a dewatering agent, actively excluding moisture from hard to get at areas. I did think about using liberal amounts of WD40 or such but as I wasn’t sure of its effect on RF gear, it was only used on some of the connectors. I also avoided the use of a high pressure washer – this can do more harm than good by destroying fine parts and pushing contaminants into inaccessible places. Gentle water flow is best. The tools I used (apart from screwdrivers, pliers etc) included a digital camera and notebook to aid reconstruction, an electrical safety tester and multimeter. Last in, first out: the receiver at the top of the pile was duly removed from the water onto our outdoor table. I started to remove the panels and was surprised at how little mud and residue was inside. The basic construction consists of a chassis/motherboard, front and rear panels, transformer, DC-DC power supply – these units can run from both AC (100-240VAC/50-440Hz) and DC (10-32VDC) – and ten shielded boards that slot into the motherboard with multiple coaxial cable connections between boards and to the rear panel. Take copious notes and pics! For complex equipment it is impor- A little daunting, perhaps – but if approached in a logical order, disassembly, cleaning and reassembly should achieve the desired result. It’s important to handle the cleaning gently, especially when it comes to things like coils and trimmers. 24  Silicon Chip tant to spend the time taking notes, photographs and maybe a little reverse engineering for diagrams. This will aid the reconstruction. A block diagram or rough circuit will help you understand the operation when it comes time to power on and you have the inevitable faults. Back to the job at hand: each of the boards had a shield front and back, with some having more push-on tin shielding inside. It turned out that this level of shielding is ideal for water containment! This emphasises the effort and importance of stripping equipment to its lowest possible level. RF/IF boards required careful attention to remove dirt and contaminants, without the movement of numerous air wound coils. Removing the brown mud residue was important; it seemed to dry well, with little electrical conduction properties. But leaving this is fraught with danger: the problem with silt-like residue is that it readily absorbs moisture in high humidity. This could easily be a problem in the future with it becoming conductive and/or corrosive. The boards themselves seemed to have a protective coating – again this helped in the restoration. Any socketed chips were carefully removed and cleaned, as were their sockets. While most modern components are impervious to methylated spirits, one problem with using it was that it attacked the dyes on the coaxial cable labels. It did not remove them completely but it is worth keeping this in mind when you spray it around – as the commercial cleaners say, test on a small area first. The other point to note is that methylated spirits is extremely flammable and due care must be taken when using it, especially from a spray-bottle. The power supply The DC-DC switch-mode power supply PCB was removed from its covers and given the same treatment as the boards. The mains transformer was more difficult. It was a toroidal type which on first look seemed to be sealed. But on close inspection I could see internal droplets of condensation on the clear wrapping. I just had to let it bake in the hot sun and hope for the best. Other devices that could trap water, such as trimpots, switches and connecsiliconchip.com.au Even if I do say so myself, the clean-up and restoration job has come up a treat. The receivers probably look a darnedsight better than when they were taken out of service. Of course, there’s been a little bit of “elbow grease” between then and now! tors could only be dried with the rest of the board and “hope for the best”. Sunbaking in Queensland So there we had it. What seemed like a thousand screws later the whole unit was reduced to its component parts, cleaned and placed on a tarp in the sun, baking. After a full day of sun, the parts were covered, left overnight, then around mid-morning the following day, the unit was re-assembled while each part was still hot from the sun. The power transformer had lost its droplets of moisture, the power switch was no longer weeping when pressed – not a sign of moisture anywhere. Fingers (and everything else!) crossed . . . By this stage I had done two units and it had taken most of two days – you have to be keen! The next step I took was to unplug the rear fan from the power supply and connect it to my bench supply. Each of the fans was connected to an independent supply and run. Both were fine, no unusual noise, they sounded just like, well, electric fans. I decided to let the fans run for another two days, drawing air through the units and hopefully removing any further moisture. Then came the electrical safety tests. As with any piece of electrical equipment, mains insulation needs to be intact (greater than 1M at a test voltage of 500V). Using a multimeter may give the same resistance reading but only with an applied voltage of a few volts. It is important to test with an electrical safety tester for this reason – the insulation needs to stand up to 500V without breaking down. Obviously, low voltage equipment doesn’t have this requirement. To do a safety test, make sure the power switch is on and all AC mains siliconchip.com.au circuits are connected and then simply short active and neutral of the mains plug and measuring between there and ground. Unit 1 was fine but unit 2 was measuring only a few thousand ohms! This turned out to be the heatshrink covering over the power switch connections trapping dirt and moisture. Removing the heatshrink and a spray of WD40 fixed that. Applying power came next. All boards were popped from their sockets, so the DC supply was only connected to the motherboard. Initially I tested the unit from DC using a 12V car battery. The DC supply burst into life and all voltages were correct – so far, so good. Next the AC – I connected it to the mains and powered up – again fine. Plugging in all the boards, reconnecting the coaxial cables and the backup battery went without a hitch as well. Soon there was static coming from the speaker. It’s alive! This receiver is controlled via software through either a GPIB or RS-232 port. Using a terminal program, I was able to initiate the self test routines. Everything passed except for the Synthesiser 2 board, which got a fail. After pulling the board out again I closely inspected what I initially assumed to be some sort of tuned, solid aluminium RF block. In fact it turned out to be a heat-transfer mechanism from a hidden SOIC socketed chip to the shield cover. Removing the block and chip, then giving it and the socket a good clean fixed this. Unit number one was now fully operational, I could tune into the local ABC AM radio station down at 612kHz all the way up to the 468MHz emergency services. As far as the operational specifications, such as selectivity etc, are concerned – I do not know as I don’t have the facilities to test this. All I know is that it works and works well, even when compared to my little Yaesu scanner. These results really show how well built these units are. Their military equipment application says they have to be – and they are made to some of the most demanding and robust construction standards. I don’t think I’d have the same success rate with such a complicated piece of electronic equipment out of a consumer factory in China (not that it might stop me trying!). Honestly, there were only three areas of iron rust stains – two screws (the rest were stainless steel), the captive screw blocks on the rear “D” connectors and the end of one feed line cable. There was some white residue on PCBs, probably an oxide of tin or lead from the solder. So if you do come across flooded gear and you think it’s worth having a go – do it! Just remember the safety of you and others when you attempt this. For 240V applications, always make sure the equipment passes electrical safety tests before plugging it in. SC And here’s the “icing on the cake” – the label might say “fully functional” but it certainly wasn’t when removed from the floodwater. 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M9914 Dick Smith Regulated AC Adaptor 4.5V - 12V DC 2.5A Dick Smith Regulated AC Adaptor 12V DC 1.5A Output Compact and powerful AC adaptor for equipment that requires a higher current source than standard AC adaptors. 4 switchable DC output voltages (4.5, 6, 9, and 12V), and can provide up to 2.5A current for each voltage. Includes 8 different sized DC output tips. M 9985 Small, lightweight regulated DC power adaptor with multi-plug output adaptors and selectable polarity. Accepts input voltages from 100 to 240 Volts AC, with 12V DC output and current rating of 1.5A. M 9915 1999 $ 698 $ save 3 $ Dick Smith Anti-Static Wet Wipes 100 anti-static lint-free wet wipe towelettes, ideal for cleaning computer, Plasma TVs, LCD TVs, CDs, DVDs, photocopiers and flat bed scanners. Not carried in all stores, but can be ordered in. N1242 1298 $ save 7 $ Dust Away Aerosol Twin Pack Gets at dust in hard to reach places without leaving residue or moisture. Great for cleaning external surfaces of keyboards, computers and cameras. 2 x 150g cans. Not carried in all stores, but can be ordered in. N0055 Offers starts 23/05/11 and ends 30/06/11 or while stocks last. All offers are for retail store stock only, with strictly limited stock available. Some items may not be available for mail orders, stock movements between stores and back orders. No rainchecks. No layby. Enthusiast electronic items are not available in all stores. Offers may not be available in some reseller or franchise stores. Please contact your local store to determine availability. 1299 $ save 7 $ Dick Smith 41-Piece Bit and Socket Set Consists of 32 security bits, nine Hex sockets, and a right-angle driver handle, all packed neatly into a plastic storage box with a clear, flip-up lid. Each bit is made from tough steel alloy. Not stocked in all stores, but can be ordered in. T4511 19 Range Digital Multimeter 2 for the price of 1 Handy test gear for making basic measurements in the car, boat or home. LCD screen, 10A max DC current, 2000 count operation, 10MOhm DC input impedance. Includes test leads, fitted battery and user manual. Not carried at all stores, but can be ordered in. Q1467P This gutsy little speed controller has a wide range of applications and is simple to build and use. There are no software settings to fiddle with but it does have some really useful features such as low-battery protection, soft start and adjustable pulse frequency. It can run from 12V or 24V batteries at currents up to 20A. By JOHN CLARKE 20A 12/24V DC Motor Speed Controller Mk.2 Upgraded version of our very popular speed controller T HE MOTOR SPEED Controller described in the June 1997 issue of SILICON CHIP has to be one of the most popular projects we have presented; many thousands have been built. But as popular as it’s been, readers have often requested simple modifications to suit myriad applications. So we have come up with a revised design which should cope with virtually every possible variation that readers are likely to envisage. That’s a brave statement but it is based on literally hundreds of emails and letters we have answered on the original project in the 14 years since it was published. The original design is still OK but we strongly recommend this new ver28  Silicon Chip sion since it has more capabilities and is easier to build and connect. In fact, if you have an unassembled version of the old kit, we suggest you toss the old PCB and buy the new PCB plus a few extra bits to make up the new design; it will be worth it. New features First, the new PCB has provision for an on-board speed control trimpot (VR1) or as most builders seem to want, an off-board potentiometer. For ease of wiring, we have added heavy-duty screw terminals to the PCB for the power supply and motor connections. As well, the in-line fuse and fast recovery power diode are now mounted on the PCB and the power Mosfets and power diode have small heatsinks fitted. The circuit now provides full range speed control from zero to full power; the older design did not allow full speed. Apart from letting the motor operate at full power it also eliminates switching noise caused by the controller (at the full speed setting). Variable pulse frequency is another new feature. Because the speed controller works by pulse width modulation, with the pulse width varying the voltage fed to the motor, this can produce more noise from the motor. This is due to magnetostriction of the core laminations and rattling of the siliconchip.com.au OUTPUT CONTROL Vcc 13 6 Rt INSIDE THE TL494 OSCILLATOR 5 8 D DEADTIME COMPARATOR Ct Q Q1 FLIP FLOP 0.12V CK 0.7V 9 11 Q Q2 10 DEADTIME 4 CONTROL PWM COMPARATOR 0.7mA ERROR AMP 1 Vcc 12 UV LOCKOUT ERROR AMP 2 4.9V 5V REFERENCE REGULATOR 3.5V 1 3 2 FEEDBACK PWM COMPARATOR INPUT 15 16 Fig.1: the circuit is based on a TL494 Switchmode Pulse Width Modulation (PWM) Control IC. External timing components RT & CT on pins 5 & 6 set the PWM frequency, while output transistors Q1 & Q2 can be configured for either push-pull or single-ended operation. armature windings. You can often reduce this lamination noise by changing the pulse frequency and there is a trimpot (VR3) on the PCB to provide this feature. As mentioned above, we have also provided low-battery protection. This is mainly to prevent damage when the circuit is powered from 12V sealed lead-acid (SLA) batteries which will fail completely if they are discharged below 11V. Soft start is also included. This will bring the motor smoothly up to speed each time power is connected to the circuit, regardless of the speed setting. If soft start is not required, it can be disabled by removing a jumper link. What’s not in the new version? The answer is speed regulation. That is where the circuit reacts to an increase in load on the motor by increasing the pulse width, thereby better maintaining the preset speed. The June 1997 version of this circuit did have a form of speed regulation in that there was feedback from the negative side of the motor to one of the error amplifiers. However, since it did not monitor the motor’s back-EMF by itself, it could not really provide full speed regulation. Nor could it provide full speed operation which this latest version does. The new 12-24V DC Motor Speed Controller is presented as a bare PCB. siliconchip.com.au 7 14 GND REF OUTPUT This can be mounted within an existing enclosure using the four mounting holes with stand-offs and screws. Alternatively, the PCB can be clipped into a standard UB3 plastic case measuring 130 x 68 x 44mm. Pulse width modulation The circuit for the 12-24V DC Motor Speed Controller is based on a TL494 Switchmode Pulse Width Modulation (PWM) Control IC. Its block diagram is shown in Fig.1. An internal sawtooth oscillator sets the PWM frequency, as determined by external timing components RT and CT. The oscillator frequency is fed to two comparators (dead-time and Main Features • • • • • • • • 20A current rating 12V or 24V operation On-board trimpot or external potentiometer for speed adjustment Optional soft start 0-100% speed control range Efficient PWM control PWM frequency adjustment Low battery protection PWM) and the resulting PWM signal gated through a 4-input OR gate to a flipflop and thence to the steering control logic for transistors Q1 & Q2. Q1 & Q2 can be configured to provide push-pull or a single-ended output, as set by the output control input (pin 13). Our circuit ties pin 13 Specifications Supply Voltage ............................................................................................ 12-30VDC Supply Current ......................................................................................20A maximum Output Current ......................................................................................20A maximum Standby Current ................................................................................................. 20mA Control Range ................................................................................................. 0-100% Low Voltage Cut-out ....................................... typically set for 11.5V (for 12V battery) or 23V for a 24V battery Pulse Frequency Adjustment ..............................~100Hz to 1.1kHz (129Hz to 1.28kHz measured on prototype) Soft Start ...............................................from 0-100% (or to set speed) over about 1s Mosfet gate rise and fall times .......................................... 1.5μs & 1.6μs respectively June 2011  29 Parts List 1 PCB, code 11106111, 106 x 60mm 1 UB3 plastic box, 130 x 68 x 44mm (optional) 1 4-way PC-mount screw terminal block with barriers (9.5mm spacing) (Jaycar HM-3162 or equivalent) (CON1) 1 3-way screw terminal block with 5.08mm pin spacing (CON2) 3 TO-220 tapped, finned heat­ sinks, 16 x 22 x 16mm (Jaycar HH-8516) 2 3AG PC-mount fuse clips 1 20A 3AG fast-blow fuse (F1) 1 DIP16 IC socket (optional) 1 TO-220 silicone insulating washer and insulating bush 2 M4 x 15mm screws 2 M4 nuts 4 M3 x 10mm screws 4 M3 x 6mm screws (optional) 1 M3 nut 1 6mm M3 tapped standoffs (optional) 1 2-way pin header for LK1 (2.54mm pin spacing) 1 jumper shunt (LK1) 5 PC stakes (TP1-TP5) 1 2N5484 or 2N5485 N-channel JFET (Q4) 1 MBR20100CT dual 10A 100V Schottky diode (D1) 5 1N4148 switching diodes (D2-D6) 2 15V 1W zener diodes (1N4744) (ZD1,ZD2) Semiconductors 1 TL494N Switchmode Pulse Width Modulation Control Circuit (IC1) 1 LM2940CT-12 12V low dropout regulator (REG1) 2 IRF1405 55V 169A N-Channel Mosfets (Q1,Q2) 1 BC327 PNP transistor (Q3) Resistors (0.25W, 1%) 3 100kΩ 1 1kΩ 2 10kΩ 2 47Ω 2 2.2kΩ low to select single-ended operation, with Q1 & Q2 driven together up to a possible 100% duty cycle, ie, full on. Dead-time normally refers to pushpull operation and is the time between Q1 switching off and Q2 turning on. But we are not using push-pull operation in this circuit so the only time it comes into play is when the “soft start” feature is enabled. In this case, the dead-time comparator increases the PWM duty cycle as the voltage to the dead-time input, pin 4, slowly drops in voltage after power is applied. The TL494 includes a 5V reference regulator and we use it here as a bias source for the two error amplifiers. Error amplifier 1 is used for the speed 30  Silicon Chip Capacitors 1 22µF 16V low-ESR PC electrolytic 4 10µF 16V PC electrolytic 1 1µF monolithic ceramic 1 470nF MKT polyester 3 100nF 63V or 100V MKT polyester (one required across motor terminals) 1 56nF MKT polyester Trimpots 1 10kΩ miniature horizontalmount trimpot or 1 10kΩ linear potentiometer (VR1) 1 10kΩ top-adjust multi-turn trimpot (3296W style) (VR2) 2 100kΩ top adjust multi-turn trimpots (3296W style) (VR3,VR4) Resistors for testing 1 1kΩ 0.5W resistor (for 12V supply) or 1 2.2kΩ 0.5W resistor (for 24V supply) control function while error amplifier 2 is used for the low-voltage cut-out function. The outputs of the two error amplifiers are ORed together by internal diodes and the commoned output used to control the PWM comparator as well as being made available at pin 3. Two under-voltage (UV) lock-out Schmitt trigger comparators monitor the reference regulator output and the supply voltage. These comparators switch off the PWM output when the reference regulator drops below about 3.5V (eg, if it is shorted) or if the supply voltage drops below 4.9V. But just to confuse the issue, we don’t use these comparators for the low-battery pro- tection; instead, we use error amplifier 2, as mentioned above. Circuit details The full circuit of the DC Motor Speed Controller is shown in Fig.2. The motor speed is adjusted using onboard trimpot VR1 or an external potentiometer connected to CON2. This varies the voltage applied to the IN1+ input (pin 1) of internal error amplifier 1 in the TL494. This is configured as a unity-gain amplifier to buffer the input voltage from the speed-control pot. Trimpot VR2 is connected in series with VR1 to adjust the voltage range for VR1. With VR2 adjusted correctly, the full rotation of VR1 will give the full speed control from 0-100% PWM duty cycle. In this case, 100% duty cycle means that the output Mosfets are fully turned on and so there is no pulse width modulation; the motor is fed with smooth DC. As already noted, pin 13 of IC1 is tied low for single-ended operation. The collectors (C1 & C2) of the internal transistors are tied together to the Vcc supply while the common emitters (E1 & E2) at pins 9 & 10 are tied to ground via a 2.2kΩ resistor. When the internal transistors are switched on, the gates of Mosfets Q1 & Q2 are driven high via diode D2 and their 47Ω gate resistors. 15V zener diodes ZD1 & ZD2 protect the gates from positive transient voltages above 15V and also from voltages below ground (clamped to -0.7V) When the internal transistors are switched off, the 2.2kΩ resistor on pin 10 pulls the base of transistor Q3 low and this in turn discharges the gate capacitances of Q1 & Q2 to rapidly switch them off, within less than 2μs. The drains of Mosfets Q1 & Q2 connect to the M- motor terminal and they act as a “low side” switch, pulling one side of the motor low while the other side of the motor connects to the full supply voltage. Fast recovery diode D1 clamps the transient spike voltages generated each time the Mosfets switch off to about 0.7V above the battery supply. Soft start As noted above, the dead-time control input is pin 4. Normally this pin should be at 0V so that the PWM duty cycle is set by trimpot VR1 or the external potentiometer at CON2. However, when power is first applied to the circuit, a 10µF capacitor consiliconchip.com.au +12-30V REG1 LM2940CT-12 22 F 16V GND 470nF 100k TP3 OUT IN 10 F 16V LOW ESR 100nF 16 15 K LOW VOLTS VR4 CUTOUT 100k VR2 10k C2 TP5 SPEED VR1 10k 11 D2 A +IN2 E1 –IN2 E2 CUT THESE TRACKS ON THE PCB TO USE AN EXTERNAL POT 2 1 9 10 E B 1k 2.2k IC1 TL494 47 –IN1 +5V +IN1 IRF1405 S K ZD1 15V 1W SOFT START D Q1 G A LK1 6 Rt Ct 10k VR3 100k Q4 2N5485 G 5 GND 7 100nF OUTPUT 13 A 100k D S D4 56nF K TP4 A 2.2k K D3 10 F D5 A B K E 2N5485 12-24V 20A DC MOTOR CONTROLLER S G LM2940 BC327 ZD1, ZD2 A –0.3V K A K D2–D5: 1N4148 2011 A FB PWM DEAD 4 TIME SC  S K C MMC FREQUENCY ADJUST Q2 IRF1405 G ZD2 15V 1W Q3 BC327 1 F TP1 D 47 K 10 F CON2 A2 A1 8 100k 3 EXT SPEED POT CON1 D1 MBR20100CT C1 10k D6 A M+ 12 Vcc 14 REF OUT 10 F M– K TP2 +5V 0V F1 20A D IN C MBR20100 A1 K GND OUT K IRF1405 G A2 GND D D S Fig.2: the complete circuit for the 12-24V DC Motor Controller. IC1 is configured for single-ended operation and its common emitter outputs at pins 9 & 10 drive parallel Mosfets Q1 & Q2 via diode D2 and their 47Ω gate resistors. Q3 ensures that the Mosfets switch off quickly when the internal transistors switch off. nected between the 5V reference and pin 4, initially holds pin 4 at +5V. This voltage gradually drops to 0V as the capacitor charges via the 100kΩ charge resistor. While ever the voltage at pin 4 is above about +2.8V, it sets the duty cycle at 0%, ie, no voltage is applied to the motor. As the voltage falls below 2.8V, the duty cycle progressively ramps up to that set by VR1. The maximum duty available when the dead-time input is at 0V is about 92%. This restriction in duty cycle is absolutely necessary when the TL494 is used in the push-pull configuration, where the output transistors siliconchip.com.au are switched on and off alternately. However, we are using this circuit in single-ended mode and we don’t need it; we want to be able to provide a 100% duty cycle, ie, full on. The restriction in duty cycle to 92% is set by a 0.12V offset applied to the dead-time comparator input from pin 4. This is shown on Fig.1. To negate the effect of this 120mV offset, we need to generate a small negative voltage to cancel it. This is something the chip designers probably never envisaged but we have come up with a devious scheme. It involves feeding the sawtooth oscillator signal at pin 5 to the gate of junction FET (JFET) Q4 which is connected as a source follower. It is used to drive a diode pump consisting of diodes D3 & D4, together with the 56nF and 10µF capacitors. Diode D5 prevents the negative voltage going beyond about -0.3V. The reason it clamps to -0.3V rather than the typical -0.6-0.7V is due to the very low current flow through D5. This negative voltage is then fed to pin 4 via a 100kΩ resistor and this cancels the 120mV offset. Is that sneaky or not? Pulse frequency variation As mentioned earlier, we have made provision to vary the PWM switchJune 2011  31 D6 100nF F1 20A MAX. 2.2k 100k D2 D1 H1 Q1 47 M+ +M TP3 22 F LOW ESR REG1 TP1 H3 15V 2.2k CON1 D3 10 F 11160111 4148 10 F TP4 15V VR3 4148 100nF D4 VR1 4148 D5 Q3 D E EP S R O T O M A 0 2 Q2 ZD2 47 10k 100k x Q4 H2 10 F 1k VR2 4148 CON2 IC1 TL494 100k 10 F TP2 LK1 1 F 56nF TO EXTERNAL SPEED POT VR4 0V +12-30V V21+ V0 4148 M-M TP5 10k ZD1 470nF Fig.3: follow this layout diagram to install the parts on the PCB but leave VR1 out if you are using an external speed control pot. Note that diode D1 (but not Q1 or Q2) must be insulated from its heatsink – see Fig.4. M3 TAPPED HOLE HEATSINK SILICONE WASHER M3 x 10mm SCREW INSULATING BUSH x D1 PCB Fig.4 (above): this mounting arrangement shows how diode D1 is insulated from its heatsink using an insulating bush and silicone washer. Fig.5 (right): cut the tracks indicated here if you install trimpot VR1 but later decided to use an external speed control pot (see text). ing frequency because it allows you to use a setting which produces the minimum “singing” noise from the motor laminations. Hence, the oscillator frequency is set by varying the resistance from pin 6 to the 0V line using 100kΩ multiturn trimpot VR3. This provides a frequency range of adjustment between about 120Hz and 1.2kHz. Although the input voltage can be anywhere from 12-30V or a little more, to cope with 12V or 24V lead acid batteries, the TL494 is run from a 12V low-dropout regulator REG1 (LM2940CT-12). This can provide a 12V output with an input voltage that is only 0.5V above 12V. As the input voltage drops below this, the regulator’s output will also drop in value but the circuit will continue to function until the supply drops below the preset low-voltage cut-out which we will come to in a moment. 32  Silicon Chip CUT THESE TRACKS WHEN USING AN EXTERNAL SPEED POT (UNDERSIDE OF PCB) REG1 can cope with supply voltage spikes up to 45V which is important if the circuit is run from a 24V battery; in a vehicle, this can range up above 29V and motor spikes will add to that. The IN2- input, pin 15, which monitors the battery voltage is connected via a 100kΩ resistor and is protected by diode D6, so reverse voltage will cause no problems there. For the rest of the circuit, if the battery supply is reverse connected, heavy current will flow through the integral diodes within Q1 & Q2, via forward biased diode D1 and fuse F1 which will blow and prevent any damage. Low-battery protection We already mentioned that error amplifier 2 provides this function and the low voltage setting is provided by trimpot VR4. You can monitor the voltage setting at test point TP5. The set-up procedure is described later in this article. However, there is a little more to the story because we can’t simply have the circuit cutting off when the battery voltage drops below 11.5V (for a 12V lead-acid battery). What would happen is that when the circuit stops operating, the battery voltage will inevitably bounce back up again because the current drain suddenly drops. So if the battery voltage goes back up, the circuit starts operating again and then it goes off again and so on. The result is that the motor will get rapid bursts of power as it stutters on an off; not good. We get around that problem by adding hysteresis to the low-voltage cut-out function. So instead of simply biasing the +IN2 input, pin 16, from the +5V output at pin 14, we also connect it to the PWM input at pin 3 via a 100kΩ resistor. Now when the speed controller is working normally, the voltage at pin 3 will vary between 2.5V at 0% duty cycle and 0.7V for 100% duty cycle and this causes the voltage at the IN2+ input to vary between +4.61V and +4.77V. However, when a low-battery condition is detected, the PWM comparator output at pin 3 is forced high to nearly +5V and this means that the +IN2 input at pin 16 is now very close to +5V (instead of between +4.61V and +4.77V). Hence, for normal operation to resume, the -IN2 input at pin 15 must rise above +5V and that effectively means that the battery voltage has to siliconchip.com.au increase by about 0.8V, a fairly big increase. By the way, if you need more hysteresis, just reduce the 100kΩ resistor, eg, to 91kΩ or 82kΩ. This view shows the completed unit, wired with an external speed control pot. Note the insulating bush and silicone washer used to isolate diode D1 from its heatsink. The complete board can be clipped into a standard UB3 utility box. Construction The 20A 12/24V DC Motor Controller is built on a PCB coded 11106111 and measuring 106 x 60mm. Fig.3 shows the assembly details. Begin by checking the PC board for breaks in the tracks or shorts between tracks and pads. That done, check that the hole sizes are correct by test fitting the larger parts (fuse clips, screw terminal blocks, Mosfets Q1 & Q2, etc). The four corner holes should each be drilled to 3mm. Start the assembly by installing the resistors, followed by diodes D2-D6 and zener diodes ZD1 & ZD2. Table 1 shows the resistor colour codes but you should also check each resistor using a digital multimeter (DMM) before installing it. Take care with the diodes and zener diodes – they must be orientated exactly as shown on Fig.3. Once these parts are in place, install a socket for IC1. Alternatively, this IC (TL494) can be soldered directly to the board. Make sure it is orientated correctly. The capacitors can then go in and again the electrolytic types must be oriented correctly. Follow with the trimpots but leave trimpot VR1 out if you intend using an external potentiometer for speed adjustment. Trimpots VR2-VR4 are all multi-turn types and should be orientated as shown. Note that VR2 is a 10kΩ unit while VR3 & VR4 are both 100kΩ trimpots. Don’t mix them up. The 3-way screw terminal block is next on the list. Make sure it is correctly seated against the board and that its openings face outwards before soldering its pins. The 4-way terminal strip can then go in. It’s secured to the board at either end using two M4 x 15mm screws and M4 nuts. Tighten the mounting screws firmly before soldering its leads to the PCB. The two fuse clips are next. Note that these must both be orientated with their end stops towards the outside. If you get them the wrong way around, you will not be able to install the fuse afterwards. Don’t be tempted to solder the fuse clips with the fuse in place. If you do, the heat may partially melt the solder used to secure the fuse wire to the end Table 2: Capacitor Codes Value 1µF 470nF 100nF 56nF µF Value 1µF 0.47µF 0.1µF 0.056µF IEC Code 1u0 470n 100n 56n EIA Code 105 474 104 563 Table 1: Resistor Colour Codes o o o o o o siliconchip.com.au No.   3   2   2   1   2 Value 100kΩ 10kΩ 2.2kΩ 1kΩ 47Ω 4-Band Code (1%) brown black yellow brown brown black orange brown red red red brown brown black red brown yellow violet black brown 5-Band Code (1%) brown black black orange brown brown black black red brown red red black brown brown brown black black brown brown yellow violet black gold brown June 2011  33 Fig.5: this scope grab shows the controller’s operation at a low setting, ie, a duty cycle of 15%. The top (yellow) trace is the signal applied to the gate of Mosfet Q1 and has an amplitude of 11.9V. Each positive gate pulse turns on the Mosfets and pulls the motor’s M- terminal low, as shown by the green trace. The blue trace shows the battery voltage at the motor’s M+ terminal. Each time the gate voltage drops to zero (ie, at the end of each positive gate pulse), the Mosfets turn off and the motor voltage rises to a spike above the blue (battery voltage) trace. Schottky diode D1 stops it rising a great deal higher. Fig.6: this scope grab shows the operation at a much higher setting, with a duty cycle of 80.3%. In this case, the positive gate pulses (yellow trace) are much longer, at 1.83ms. Now, each time the Mosfets turn off, they generate an even higher spike voltage. caps and you could get an open circuit or dry joint. Hint: you can use sticky tape to hold the fuse clips (and other parts) in place while you solder them. Follow by installing PC stakes at test points TP1-TP5 and the 2-way header for LK1. A shorting jumper can then be fitted to this header to enable the soft start feature. Installing the semiconductors Transistors Q3 (BC327) and Q4 (2N5485) can now be fitted, followed by regulator REG1 which is mounted horizontally on the board. The latter is installed by first 34  Silicon Chip bending its leads down at right angles so that they pass through their mounting holes. REG1’s tab is then secured to the PCB using an M3 x 6mm machine screw and nut, after which the leads are soldered. Don’t solder REG1’s leads before securing its tab. If you do, you could crack the board tracks as the mounting screw is tightened down. Mosfets Q1 & Q2 and Schottky diode D1 are each mounted vertically and fastened to separate small heatsinks. The three heatsinks are installed first, by soldering their locating pins to the relevant PCB pads. Make sure that the heatsinks are properly seated against the PCB before soldering them in place. That done, slide Q1 & Q2 into their mounting holes and fasten them directly to their respective heatsinks using M3 x 10mm machine screws (the heatsinks come pre-tapped). Tighten the screws firmly, then solder their leads. Diode D1 is mounted in a similar way except that it requires an insulating bush and silicone washer to insulate its tab from the heatsink. Fig.4 shows how this is done. As before, tighten the screw firmly before soldering its leads. Finally, use your multimeter to confirm that D1’s metal tab is indeed isolated from its heatsink (and from the metal tabs of Q1 & Q2). Testing Before moving on to the test procedure, note that a 100nF MKT capacitor should be connected directly across the motor’s terminals. This is necessary to reduce electromagnetic radiation from the motor. If you are using an external 10kΩ potentiometer for the speed control, connect this up now. Conversely, if you are using trimpot VR1 instead, this should be installed on the PCB. If you do install VR1 but later decide that you want to use an external pot, then you must cut the PCB tracks running to the top of the this trimpot and to its wiper. This is necessary to prevent the trimpot and the external potentiometer acting in parallel Fig.5 shows which tracks to cut. These tracks have been deliberately thinned at the indicated locations and can be cut using a sharp hobby knife. If necessary, they can later be rejoined using solder bridges (ie, if you want to revert to using the trimpot). Alternatively, you can leave the tracks intact and remove the trimpot instead. The completed unit can now be tested by following this step-by-step procedure (without the motor connected): (1) Connect a 1kΩ 0.5W resistor between the M+ and Mterminals and apply 12-15V DC to the supply terminals (ie, to the +12-30V and 0V terminals). Watch the polarity. Note that a 24V DC supply can also be used but in that case, you should connect a 2.2kΩ 0.5W resistor between the M+ and M- terminals. (2) Connect a digital multimeter (set to volts) between test points TP1 (ground, bottom left) and TP3 (above REG1). This lets you check the regulator voltage. You should get a reading on TP3 of somewhere between 11.4V and 12.6V, provided the supply voltage is above 13.6V. TP3’s voltage may be slightly lower if the supply voltage is less than 13.6V. If TP3’s voltage is below the expected range, check for incorrectly oriented components (eg, IC1 and the electrolytic capacitors) and for short circuits between tracks. (3) Check that the reference voltage on TP2 is between siliconchip.com.au 4.75V and 5.25V. If not, check for a short circuit from pin 14 of IC1 to 0V. (4) Assuming all is correct, adjust VR1 (or the external pot) fully anti-clockwise and check the voltage on the centre terminal of CON2. Adjust trimpot VR2 so that this voltage is the same as that previously measured at TP2 (ie, between 4.75V and 5.25V). (5) Check that the “dead-time” offset voltage between TP4 & TP1 is at about -0.3V. If this is a positive voltage, check the value of the 100kΩ resistor at D5’s cathode and that D3-D5 are orientated correctly. The 10µF capacitors across D5 and on pin 4 of IC1 should also be checked for correct polarity. (6) Adjust VR4 so that the voltage between TP5 & TP1 is above the TP2 voltage (if this is not done, the PWM drive will not operate due to low-voltage detection). (7) Connect a DMM set to read DC volts across the M+ and M- terminals. Adjust the speed control pot (or trimpot VR1) and check that the output voltage varies accordingly. With the speed pot fully anticlockwise, the measured voltage between M+ and M- should be 0V. As the pot is wound clockwise, this voltage should rise. The maximum level should be very close to the supply voltage. Fig.7: this shows an intermediate speed setting, with a duty cycle of 53.7% and a gate pulse width of 1.225ms. Note that when the Mosfets turn off, the M- voltage briefly rises above the battery voltage (M+). It then falls to a plateau value which represents the motor’s back-EMF. Note that there is also some hash on this waveform and this is due to brush and commutator hash. Control range At this stage in the adjustment procedure, the voltage between M+ and M- should reach its minimum well before the speed control pot is wound fully anticlockwise. You now need to readjust VR2 to broaden this range. To make this adjustment, wind the speed control pot fully anticlockwise and adjust VR2 clockwise so that the voltage between M+ and M- just starts to rise above 0V. That done, slowly adjust trimpot VR2 back anticlockwise until 0V is reached, then back it off slightly further by about a half turn. Low-voltage cut-out Trimpot VR4 sets the low-voltage cut-out. To set this at 11.5V, first measure the battery supply voltage and subtract 0.6V from this measurement. That done, multiply the result by 0.426, then adjust VR4 so that the voltage on TP5 measures this calculated value. For example, if the battery voltage is 12V, then (12 - 0.6) x 0.426 = 4.86V. VR4 is therefore adjusted to give a reading of 4.86V at TP5. When the battery voltage drops to 11.5V, TP5’s voltage will fall to 4.65V and the low-voltage cutout will activate at close to this voltage (ie, between 4.61V and 4.77V). The battery voltage required for the circuit to switch on again is 12.33V – ie, (5V ÷ 0.426) + 0.6V. If you have an adjustable power supply, the low-battery cut-out action can be tested. To do this, first set the speed pot to its mid-point, so that there is a voltage between the M+ and M- terminals. Now reduce the supply voltage until the voltage between the M+ and M- terminals suddenly drops to 0V. The supply voltage at which this occurs is the battery cut-out voltage and should be close to 11.5V. If necessary, adjust VR4 to give a more accurate cut-out voltage. For a 24V battery, the low-battery cut-out voltage can be set to 23V. In this case, measure the battery supply voltage and subtract 0.6V. Now multiply the result by 0.208 and adjust VR4 so that the voltage at TP5 equals the calculated value. siliconchip.com.au Fig.8: this scope shot illustrates the clamping action of the fast recovery diode (D1). Taken at a much faster scope horizontal sweep speed, it clearly shows the diode action. Note that there is quite a lot of ringing on both the battery supply line (M+ blue trace) and the M- line (green trace). So even with the ringing, the diode faithfully clamps the M- line just above the M+ line. It actually appears to clamp at about 1V above the supply line but the real value is less than 1V. That completes the adjustment procedure and you can remove the resistor that’s across the M+ and M- terminals. Tweaking the PWM frequency As stated, the motor may generate an audible noise due to the Mosfets switching on and off at the PWM frequency. VR3 can be adjusted to minimise this noise, although it may not be possible to completely silence it. A 100nF MKT polyester capacitor connected directly across the motor terminals can also help reduce motor noise (and reduce SC electromagnetic interference). June 2011  35 Make high-quality audio recordings with this . . . USB Stereo Recording & Playback Interface It uses balanced mikes and has S/PDIF & line inputs as well By JIM ROWE Now you can use your laptop PC to make high-quality stereo audio recordings with professional standard balanced microphones. This interface unit lets you make recordings at sampling rates up to 48 kilosamples/second and provides high-quality stereo analog line outputs for playback or monitoring. There’s also an S/PDIF digital audio input for recording and an S/PDIF digital audio output for playback. 36  Silicon Chip siliconchip.com.au VCCCI VCCP1I VCCP2I VCCXI VDDI INSIDE THE TEXAS INSTRUMENTS PCM2902 5V TO 3.3V LDO REGULATOR S/PDIF DECODER USB PROTOCOL CONTROLLER VINL FIFO ADC VINR Vcom SSPND POWER MANAGER LOCK DIN SELECTOR USB TO HOST ISOCHRONOUS IN ENDPOINT USB SIE TRANSCEIVER CONTROL ENDPOINT ANALOG PLL DAC DOUT 12MHz XTAL SEL0 SEL1 ISOCHRONOUS OUT ENDPOINT HID0 HID ENDPOINT S/PDIF ENCODER XTI D+ ANALOG PLL FIFO PLL (X8) D– DGNDU VOUTL VOUTR Vbus (+5V) 96MHz HID1 HID2 TRACKER (SPACT) AGNDC XTO AGNDP AGNDX DGND Fig.1: this block diagram shows what’s inside the PCM2902 stereo audio CODEC IC. It provides line-level analog stereo inputs & outputs, an S/PDIF digital audio input, an S/PDIF output and a full-speed USB interface. W HILE MOST LAPTOPS have a built-in sound card, they’re no good for high-quality audio recordings. Most built-in sound cards are of somewhat indifferent quality when it comes to the recording side and they don’t provide balanced inputs for professional type microphones, which are really necessary for making highquality recordings. Hence, if you want to use a laptop, you need an “audio front-end” with balanced-input microphone preamps feeding a pair of high-quality analogto-digital converters or “ADCs”. And since most laptops have at least one USB port, the easiest way to connect such an audio front-end to them is via a USB cable. This has the added advantage of allowing the audio frontend to draw its power from the laptop, via the same cable. So that was the rationale behind the low-cost audio front-end unit we’re describing here. Or at least, those were our basic goals when we started its development. Along the way it “grew some” when we realised that it wouldn’t be too difficult to provide it with various bonus features: siliconchip.com.au (1) line-level analog stereo recording inputs; (2) line-level analog stereo outputs for playback and/or monitoring; and (3) S/PDIF digital audio input and output for direct digital recording and playback. In effect, it has become a flexible multi-purpose USB audio interface – not just for laptops but for virtually any PC. It’s easy to build and much lower in cost than comparable commercial units. What’s more, there’s no software to install – you just connect it up and it runs on Windows XP SP3, Windows Vista and Windows 7 (both 32 & 64bit). It should also work with recent Linux and Mac operating systems. What’s inside? The heart of the project is the PCM2902 from Texas Instruments. This was originally developed by BurrBrown, which was acquired by TI not long ago. The PCM2902 is described as a single-chip stereo audio CODEC with an inbuilt full-speed USB protocol controller, SIE (serial interface engine) and transceiver. As well as providing line-level analog stereo inputs for recording and line-level stereo outputs for playback, it includes an S/PDIF digital audio input for recording and an S/PDIF output for direct digital playback. And of course, it has an inbuilt full-speed USB interface. Fig.1 shows the goodies packed inside the PCM2902. To the right of centre is the USB protocol controller block which provides four main USB “end-points”: (1) a control end-point which receives control commands from the PC host; (2) an HID (human interface device) end-point which allows inputs to the chip to generate keypress events on the host PC, to control muting, volume, etc; (3) an isochronous IN end-point which handles the transfer of audio recording data from the ADC section IN to the PC via the USB; and (4) an isochronous OUT endpoint which handles the transfer of audio playback data OUT of the PC via the USB, feeding it to the DAC section. Don’t worry too much about these terms but you might like to know that “isochronous” means that the audio data packets are transferred at a conJune 2011  37 What The Acronyms Acronym s Mean ADC: an analog-to-digital converter, which samples incoming analog (audio) at a designated rate such as 44,100 samples per second and outputs the samples as a digital serial bitstream. A stereo ADC samples both channels simultaneously but interleaves the samples in the output bitstream (ie, L-R-L-R and so on). CODEC: short for “coder/decoder” – basically a combination of one or more ADCs with one or more DACs. It can also include functional blocks for encoding and decoding the digital samples. DAC: a digital-to-analog converter, which converts digital data samples into the equivalent analog voltages or currents. A stereo audio DAC is really two separate DACs, one of which converts the left channel samples in the incoming bitstream, while the other DAC converts the right channel samples. FIFO: a First-In-First-Out buffer, which provides temporary storage for a stream of digital data. Although it functions like a serial delay line, most FIFOs are actually implemented with dual-ported random-access RAM. LDO: a Low-DropOut voltage regulator – ie, one which requires a very small difference between the unregulated input voltage and the regulated output voltage in order to operate correctly. PLL: a Phase-Locked Loop, which is a functional block designed to lock an oscillator to an exact multiple or sub-multiple of a frequency from another oscillator. SIE: short for “Serial Interface Engine”. A functional block which manages the packaging/transmission and reception/unpackaging of data transferred via a serial interface like USB. S/PDIF: the Sony/Philips Digital Interface Format, a protocol and physical layer specification used to transport digital audio signals between devices and components. The signals can travel over either a coaxial cable or an optical fibre cable (in the latter case it is usually called “TOSLINK”). It is a consumer-level adaptation of the original AES/EBU (Audio Engineering Society/European Broadcasting Union) standard for professional digital audio. The serial audio data stream is encoded with “biphase mark coding”. TOSLINK: short for Toshiba Optical Serial Link, the version of S/PDIF which uses optical fibre cables to carry the digital audio bitstream. USB: short for “Universal Serial Bus”, the serial data communications bus now very widely used to link PCs with a broad range of peripheral devices. The original USB 1.0/1.1 standard supported communication at Low Speed (1.5Mbits/second) and Full Speed (12Mb/s). When USB 2.0 was subsequently introduced this also covered High Speed (480Mb/s), while the recently adopted USB 3.0 standard adds Super Speed (5Gb/s). USB 1.1 and 2.0 use a standard 4-wire cable, with different connectors at each end – Type A for connection to the “downstream” port of the PC or an intermediate hub, and Type B for connection to the “upstream” port of the USB peripheral device. stant rate (isochronous = equal time). You might also want to note that we’re not actually making use of the HID end-point in this project. To the right of the USB protocol controller block are the USB SIE and transceiver sections which transmit and receive all the data and control packets transferred over the USB signal lines. Just above the protocol controller is the power manager block which controls the power taken by the external circuitry, as directed by the host PC’s USB driver. Thus, when the PC directs the PCM2902 protocol controller to switch the device into low power “suspend” mode because no activity has been detected for a few milliseconds, the power manager block drops the logic level on the SSPND-bar output pin. This is used by external control circuitry to turn off power to everything but the “brains” of the PCM2902 chip itself. As soon as the PC directs the protocol controller to resume normal operation, the power manager pulls the SSPND-bar line high again, so power is restored to the external circuitry and 38  Silicon Chip it can get back to work. The sections to the left of the USB protocol controller block in Fig.1 are those involved in processing the record and replay signals. In the upper area, there’s the stereo ADC section for converting incoming analog audio into 16-bit digital samples, together with the S/PDIF digital audio input decoder. The digital bitstream from one of these is fed through a FIFO (first in, first out) buffer to the isochronous IN endpoint of the USB protocol controller, for transmission to the PC host. By the way, if there’s a signal from the S/PDIF input decoder it becomes the recording signal but if there is no S/PDIF signal, the bitstream from the ADCs is fed to the FIFO block as the recording signal. In the lower area of the block diagram there’s a second FIFO buffer which is fed from the protocol controller’s isochronous OUT endpoint with audio playback data received from the PC host. The output of this second FIFO is fed to the stereo DAC section to be converted into analog playback audio. At the same time, it is fed to the S/PDIF encoder section to produce a digital playback bitstream. So the playback signals simultaneously appear at both the analog audio outputs and the digital S/PDIF output. Note that the clock signals used by all parts of the PCM2902 are derived from a single 12MHz oscillator inside the chip itself (apart from the crystal and some minor components). An internal PLL (phase-locked loop) is used to multiply the crystal frequency by eight, producing a 96MHz clock that’s used to drive most of the chip’s circuitry – including the ADCs, DACs and USB control circuitry. An important feature of the PCM2902 is the “tracker” section you can see just below the USB protocol controller. This takes the 96MHz internal clock and locks it to an audio clock signal derived from the USB data packets, using what TI calls its “SpAct” architecture. This is claimed to reduce clock jitter for both recording and playback and also allows simultaneous recording and playback at different sampling rates. Note that the PCM2902’s ADCs use 16-bit delta-sigma conversion and can work at any of seven standard samsiliconchip.com.au pling rates: 8, 11.025, 16, 22.05, 32, 44.1 and 48kHz. The DACs also use 16-bit delta-sigma architecture but can only operate at the three most popular sampling rates: 32, 44.1 or 48kHz. As you can see then, the PCM2902 is a very powerful chip, containing all the main functions needed for a high-quality USB stereo recording and playback interface. Circuit description Refer now to Fig.2 for the complete circuit of the USB Stereo Recorder & Playback Interface. Now that you’ve seen inside the wondrous PCM2902 chip, you should be able to follow its operation without any problems. All the circuitry to the left of the PCM2902 itself (IC3) is concerned with preparing the incoming audio signals for recording. The left-channel analog recording circuitry is shown at top, with identical circuitry for the right channel below it. Each channel has a balanced microphone input connector (CON1 & CON3) and each of these feeds a balanced-input mic preamp using three sections of an MCP6024 low-noise, low-voltage CMOS quad op amp (IC1c,b&d and IC2c,b&a). The gain of these preamps is adjusted via a dual-gang potentiometer (VR1a & VR1b). This allows the gain to be optimised without running into overload. The maximum preamp gain is 201, which should be sufficient for most microphones. The line-level output from each mic preamp (ie, at pin 14 of IC1d & pin 1 of IC2a) is fed to its corresponding position on double-pole switch S1. Alternatively, the second position of each pole is used to select the signals from the line-level input sockets (CON2 and CON4). The signals selected by S1a and S1b are then fed to third-order active low-pass filters based on IC1a & IC2d. These fare used for “anti-aliasing” and filter out any audio components above about 22kHz. Without these filters, there could be audible alias components being generated as part of the sampling process. The outputs of the anti-aliasing filters are in turn fed to the ADC inputs of the PCM2902 (VinL at pin 12 and VinR at pin 13) via 1µF coupling capacitors. Note that because the op amps in IC1 and IC2 are being operated from a single DC supply rail (Vcc) of approximately 4.0V, they must be siliconchip.com.au Specifications Purpose: a digital stereo recording and playback interface for laptop PCs, which links to the PC via a standard USB cable and is powered from the PC’s USB port via the same cable. Features include: • Twin balanced-input microphone preamps for use with professional type microphones. • Selectable line-level stereo analog inputs. • High-quality stereo ADCs for recording at any of seven standard sampling rates (8, 11.025, 16, 22.05, 32, 44.1 and 48kHz). Built in stereo DACs for replay at any of three standard sampling rates (32, 44.1 and 48kHz). • • An S/PDIF digital audio input to allow recording directly from an S/PDIF digital audio signal, as an alternative to the analog audio inputs. • An S/PDIF digital audio output to allow playback via a high-quality digital sound system, as an alternative to the analog audio outputs. 16-bit delta/sigma ADCs and DACs. • Fully compliant with the USB 1.1 specification. • • Installs automatically on Windows XP SP3 and later operating systems (plus recent Mac & Linux systems) using the standard USBaudio.sys drivers – no custom drivers required. • Fully compatible with Windows-based audio recording and playback software such as “Audacity”. Frequency response: Recording = 20Hz - 17kHz +0dB/-1.0dB, 15Hz - 20kHz +0dB/-2.0dB; • Playback = 30Hz - 18kHz +0dB/-1.0dB, 20Hz - 21kHz +0dB/-2.0dB • Low current drain (below 70mA). biased midway between Vcc and 0V to ensure maximum output swing with minimum distortion. This Vcc/2 bias voltage is derived from a resistive voltage divider consisting of two 2.7kΩ resistors (just above IC1a). The same voltage is also used to bias the replay filters and output buffers in IC4, which we’ll come to in a moment. The only remaining part of the recording circuitry is CON5. This is the S/PDIF digital bitstream input. Its signal is simply fed into the Din input (pin 24) of the PCM2902 via a 100nF capacitor. 150nF capacitor and a resistive divider to provide the correct peak-to-peak amplitude. The external components needed by the PCM2902’s 12MHz master clock oscillator are shown just below the Dout output pin. Apart from the 12MHz crystal itself, there are two low-value NPO ceramic capacitors which are used to bring the crystal’s frequency into the correct range (12.000MHz ±6kHz), plus a 1MΩ biasing resistor to ensure that the oscillator has minimum “start-up” delay when power is applied. Replay circuit USB interface The replay circuitry is shown to the lower right of the PCM2902. The DAC output signals appear at VoutL (pin 16) and VoutR (pin 15) of the PCM2902 and are fed via 1µF coupling capacitors to active low-pass filters based on IC4b and IC4c. These two filters are identical to those used in the recording channels and remove any glitches that are present in the DAC outputs. The filtered signals are then passed through unity gain buffer stages IC4a and IC4d and fed to the line output connectors (CON7 & CON8) via 1μF capacitors. The S/PDIF digital replay output appears at the Dout pin (pin 25) of the PCM2902. This is then fed to the S/PDIF output connector (CON6) via a The only part of the circuit we haven’t yet discussed is the USB interface and power management section. Because the SIE and USB transceiver are inside the PCM2902, the external part of the USB interface is really very simple. As shown, the four pins of USB connector CON9 are connected to the corresponding pins on the PCM2902, via 22Ω suppressor resistors in the case of the D+ and D- signal lines and via a 2.2Ω current-limiting resistor in the case of the Vbus line. The +5V supply applied to pin 3 (Vbus) when the interface is connected to the PC host (via a USB cable) is passed through an LDO (low dropout) regulator inside the PCM2902. The June 2011  39 100 100nF 470nF 100k LEFT MIC INPUT 1 100k 9 2 47pF 22pF 100k BOX & FRONT PANEL 2.7k 4 Vcc/2 8 IC1c 10k 22pF CON1 3 10 IC1: MCP6024 100 LEFT CH MIC LEVEL VR1a 10k 10k 100 F 10k 10k 12 10k IC1d 14 10k MIC 5 15k 820pF 33k 82pF 3 2 1 IC1b 7 220nF 100k Vcc/2 100 100nF 100k 10 100k 2 47pF 22pF 100k BOX & FRONT PANEL 9 8 IC2c S/PDIF IN MIC/LINE INPUT SELECT IC2: MCP6024 10k 100 RIGHT CH MIC LEVEL VR1b 10k 10k Vcc 10 F 4 10k 22pF CON3 3 IC1a 11 150k 1 CON5 10k 2 3 10k IC2a 10k 1 MIC LINE 8.2k S1b 1nF 15k 820pF 33k 82pF 12 13 IC2d 14 6 470nF 5 IC2b 7 220nF 11 100k 100k SC 1nF LINE 100nF 2011 8.2k 6 470nF 470nF RIGHT LINE INPUT S1a CON2 RIGHT MIC INPUT 2.7k 13 100k LEFT LINE INPUT Vcc 10 F Vcc/2 CON4 150k 100nF USB STEREO RECORDING & PLAYBACK INTERFACE Fig.2: the circuit for the USB Stereo Recording & Playback Interface. Quad op amps IC1 & IC2 form balanced micro­phone preamp and filter stages, while IC4(a)-4(d) filter and buffer the line outputs from IC3. In addition, IC3 directly interfaces to the S/PDIF input & output sockets and to a type-B USB socket. LDO’s output in turn appears at pin 27 (Vddi). Because the D+ signal line of the USB interface is connected to this pin via a 1.5kΩ resistor, this means that the D+ signal line is pulled up to a voltage close to Vbus. According to the USB specification, this is the correct way of indicating to the PC host controller that a USB device is capable of full-speed (12Mb/s) operation. Finally, we come to the power man40  Silicon Chip agement circuitry which is based on REG1, a REG103GA-A LDO regulator made by TI. There are two features that make this regulator special. The first is that its output voltage can be adjusted, something that’s not all that common with LDOs. The second is that it’s provided with an enable input (pin 5), so its output can be turned on and off very quickly by a control signal applied to this pin. These two features, together with its use of internal DMOS circuitry to achieve an exceptionally low drop-out voltage (typically <20mV for 90mA output current) make the REG103GAA ideally suited for this sort of application. REG1’s output voltage is set to 4V by the resistive divider connected to pin 4 (ADJ). In addition, pin 5 (EN) of REG1 is connected to pin 28 (SSPND-bar) of siliconchip.com.au REG1 REG103GA-A Vcc (~4.0V) 2 A D1 1N5819 K +3.6–3.85V 10 VcccI 12 14 SSPND Vcom Vbus D– IC3 PCM2902 D+ 23 11 28 5 HID0 6 HID1 7 HID2 27 VddI 9 SEL1 8 SEL0 26 DGND VinL TANT 24 DgndU VoutL 1 F TANT 100nF 1.5k 2.2 3 TO HOST PC CON9 USB TYPE B +5V 1 22 2 1 F TANT 1 2 3 4 22 4 Din VccXI 1 F TANT GND 3,6 TANT 10 F 100nF ADJ EN 5 +5V 1 13k 10 F AgndC 1 F MKT 4 10nF 27k 100nF IN OUT 16 1 F 8.2k MKT 1nF 100k 1 F TANT 15k 820pF BOX & FRONT PANEL 33k 4 5 IC4b 82pF 7 6 3 2 IC4a 1 1 F 100 Vcc/2 13 17 VoutR VinR 8.2k Dout XTI Vcc/2 15k 1nF Vccp1I XTO 1 F TANT 1 F MKT 1 F TANT 19 15 820pF IC4: MCP6024 33k 10 82pF 9 AgndP AgndX 18 22 IC4c 8 12 13 11 IC4d 14 1 F 100 RIGHT LINE OUT CON8 220k 25 20 1M 21 150nF X1 12MHz Vccp2I CON7 220k 100k 1 F MKT LEFT LINE OUT 47pF S/PDIF OUT 220 CON6 110 39pF PCM2902 REG103GA-A 1N5819 A the PCM2902. So whether or not REG1 provides this output voltage depends not only on the presence of +5V from the PC via pin 1 of CON9 but also on the logic level of the SSPND-bar control signal derived from the power management circuitry inside IC3. If the PC directs the USB protocol controller inside IC3 to reduce the USB device’s power level and enter “suspend” mode, the power managesiliconchip.com.au K 6 1 14 28 5 ment circuitry inside IC3 pulls pin 28 down to 0V. This in turn pulls the EN pin of REG1 low and switches off the Vcc output voltage. As a result, IC1, IC2 & IC4 all shut down, as does the circuitry inside IC3 which gets its power from the Vcc line via diode D1 and pin 10 (Vccci). When the PC directs the USB protocol controller inside IC3 to resume normal operation, its power manage- 1 ment circuitry pulls pin 28 high again. REG1 then switches its output voltage (Vcc) back on again, thus restoring normal operation. At this stage, you may be wondering how the protocol controller, SIE, USB transceiver and master clock oscillator inside IC3 are able to respond to any directions from the PC after it has entered suspend mode (ie, when REG1 has turned off the power). The secret June 2011  41 S M OTT O B © 2011 TOP 2 + 22 22 REG1 27k 13k 5819 IC3 PCM2902 + D1 2.2 100nF REG103 3 1 150nF 4 10nF 110 33k 15k 8.2k 10 F IEC Code 1u0 470n 220n 150n 100n    10n    1n 820p   82p   47p   39p   22p EIA Code 105 474 224 154 104 103 102 821 82 47 39 22 1 F + 1 F 10 F 1 F 1 F + + 39pF 12.0MHz X1 1M 47pF + 1 F pin. As a result, it’s only these sections inside IC3 which “go to sleep” in suspend mode. Since these are the parts of the PCM2902 which draw the most current, they need to be shut down when the device enters suspend mode. The result of this power management system is that the total current drawn by the USB Stereo Recording & Playback Interface in suspend mode is less than 220µA; much lower than the 60-70mA drawn in operating mode. This means that it comfortably meets the appropriate USB specification – that all USB devices must be capable of entering a suspend mode, where they must draw no more than 2.5mA from the USB power line. + 1 F 1 F EARTH WIRE CONNECTS TO SCREEN LUGS OF CON1 & CON3 Fig.3: follow this diagram to install the parts on the PCB, starting with REG1 & IC3. The parts with blue outlines mount on the case lid and are connected via wire extension leads. Note that you can substitute 1μF monolithic ceramic capacitors for the 1μF tantalums shown on the overlay. here is that these sections inside the PCM2902 are all powered from the internal LDO which is fed with the +5V applied to its Vbus pin (pin 3) from pin 1 of CON9. This voltage is available all the time, as long as the device is connected µF Value 1µF 0.47µF 0.22µF 0.15µF 0.1µF 0.01µF 0.001µF    NA   NA   NA   NA   NA + 1.5k 8.2k 1 F 100 F 820pF 1 F IC4 MCP6024 15k 33k 100nF 100k 100k DGND (CON3) 100nF 82pF 1nF 100nF 1 1 F 1nF 15k 33k R MIC IN 22pF 2 100k 100k 100k 1102 © 1 107106111 160170 S 470nF USB TYPE B 1 F 220 1nF AGND (CON1) 470nF 100k 1 47pF 3 22pF 100k L MIC IN 2 + 10 F 10k 10k 10k 10k 470nF 3 100k 470nF 22pF 47pF 1 F 82pF 82pF 100 100 100 100 10k VR1 IN + 100nF 10k 10k 10 F 22pF 10k OUT L 100k 10k + E 820pF 100 8.2k IC2 MCP6024 100nF 10k 82p 10k IC1 MCP6024 33k 820pF 100 8.2k 100k 220nF 10k 150k L 150k 1nF 15k R Value 1µF 470nF 220nF 150nF 100nF 10nF 1nF 820pF 82pF 47pF 39pF 22pF CON9 220k E 100k 100k R 220nF 100nF S1 220k MIC/LINE E Table 2: Capacitor Codes SPDIF IN/OUT CON5&6 TO HOST 820pF CON7&8 2.7k LINE OUTPUTS CON2&4 2.7k LINE INPUTS to a PC host via a USB cable. Hence these sections inside the PCM2902 are always able to respond to commands from the PC. The rest of the circuitry inside IC3 (eg, the ADCs and DACs) is powered from the Vcc line via D1 and the Vccci Building it All parts except for switch S1, po- Table 1: Resistor Colour Codes o o o o o o o o o o o o o o o o o o No.   1   2   2   12   4   1   4   1   12   4   2   1   1   1   6   2   1 42  Silicon Chip Value 1MΩ 220kΩ 150kΩ 100kΩ 33kΩ 27kΩ 15kΩ 13kΩ 10kΩ 8.2kΩ 2.7kΩ 1.5kΩ 220Ω 110Ω 100Ω 22Ω 2.2Ω 4-Band Code (1%) brown black green brown red red yellow brown brown green yellow brown brown black yellow brown orange orange orange brown red violet orange brown brown green orange brown brown orange orange brown brown black orange brown grey red red brown red violet red brown brown green red brown red red brown brown brown brown brown brown brown black brown brown red red black brown red red gold brown 5-Band Code (1%) brown black black yellow brown red red black orange brown brown green black orange brown brown black black orange brown orange orange black red brown red violet black red brown brown green black red brown brown orange black red brown brown black black red brown grey red black brown brown red violet black brown brown brown green black brown brown red red black black brown brown brown black black brown brown black black black brown red red black gold brown red red black silver brown siliconchip.com.au CON9 2 REG1 27k 13k 5819 + D1 IC3 PCM2902 tentiometer VR1 (microphone gain) and the two XLR mic input sockets (CON1 & CON3) are mounted on a double-sided PCB coded 07106111. This is housed in a standard diecast aluminium box measuring 119 x 94 x 57mm. Fig.3 shows the parts layout on the PCB. Begin by checking the board for any defects (especially around IC3 & REG1), then test fit the RCA sockets to make sure their mounting holes are the correct sizes. Check also that the corner cut-outs have been made. Once that’s done, start the assembly by installing the two SMDs (IC3 & REG1). IC3 (PCM2902) comes in an SSOP-28 package, while REG1 comes in a 5-pin SOT223 package. As shown in Figs.3 & 4, both devices are mounted on the top of the board. It’s important to use a soldering iron with a very fine tip to install these two devices. You also need some finegauge resin-cored solder and some solder wick. A magnifying lamp or magnifying glass will also be handy. REG1’s pins are more widely spaced than IC3, so install it first. Start by carefully positioning the device accurately siliconchip.com.au over the pads on the board, then lightly tack solder one of its outside pins. Adjust its position if necessary, then solder the remaining pins. Note that you also have to solder its heatsink tab (opposite the pins) to the matching rectangular pad on the PCB. IC3 is a bit trickier to install but the procedure is similar. Make sure it is orientated correctly, with the dimple in the “pin 1” corner at upper right, then lightly “clamp” it into place using a pair of self-closing tweezers. Check that it is accurately positioned, then place a tiny drop of solder on the tip of your iron and just touch the tip to the end of pin 1, so that the solder flows down and “tacks” the pin to the PCB pad. Now do the same for pin 15 which is diagonally opposite, at the lower left corner of the device. These two “tacked” pins will now hold the device in place while you solder the remaining pins. Use a minimum of solder for each pin but don’t worry if you make a few inadvertent solder bridges between the tracks or adjacent pins. Once you’ve soldered all 28 pins, use a magnifying glass to check for 1.5k + 1 F 10 F + + 10 F + 1 F This view shows the completed PCB. Note that male XLR connectors are shown here but ideally they should be female, in line with the usual convention. Female XLRs can be fitted to the front panel and the connections between pins 3 and 1 of each connector swapped over between the connector’s rear lugs and the pads on the PCB. Instead of passing straight down, short lengths of insulated hookup wire can be used to make these connections, thereby ensuring there will be no accidental shorts. REG103 22 22 + 2.2 8.2k 100nF 1nF 820pF 33k 15k 100nF 82pF 3 1 150nF 1 F 220 4 10nF 110 USB TYPE B 12.0MHz X1 1M + 1 F + 39pF 47pF 1 F 1 F Fig.4: this enlarged section of the PCB shows the mounting details for REG1 & IC3. Use a fine-tipped iron to solder their pins (see text). solder bridges. If you do find any, they are quite easy to remove using a narrow strip (ie, 2mm wide) of desoldering braid or solder wick. The trick is to place the braid directly over the bridged pins (or tracks), then press the braid firmly down onto the pins using the tip of your iron for a couple of seconds. The braid then not only heats up the pins but also “sucks up” and removes the solder bridge as well. In practice, you’ll find that this is much easier to do than it sounds, especially if the PCB has a solder mask. Once you’ve finished, check all the pins again with a magnifying glass, just to make sure. It will be harder to remove any remaining problems later when the adjacent parts are in place. The “through-hole” parts can now be installed on the PCB starting with the single wire link and the resistors. Check each resistor using a digital multimeter before soldering it into place on the PCB, then fit diode D1 June 2011  43 1 9.5 9.5 23.5 A 10 9.5 14.5 11.5 A A 12.5 7 C C C 7 21 19.5 B B 12.5 B HOLE E: 6.5mm DIAM. HOLE F: 7.0mm DIAM. HOLES A: 11.0mm DIAM. HOLES B: 12.0mm DIAM. CL HOLES G: 24mm DIAM. HOLES C: 3.5mm DIAM. HOLES D: 3.0mm DIAM. ALL DIMENSIONS IN MILLIMETRES 29.7 49.25 21.5 The PCB is a neat fit inside the case. In practice though, it’s first attach­ed to the lid before the entire assembly is dropped into place. Note our comments on P43 about using female XLR connectors. D D E 28.5 17 F 4.5 D 17.5 9 D CL 9 Drilling the case 13 8 25 31 G G D 12.25 D 9 D D 9 (LID OF BOX BECOMES FRONT PANEL) Fig.5: this is the drilling template for the case. Start each hole with a small pilot drill to ensure accuracy and use a tapered reamer to enlarge the holes for the RCA sockets (A & B). The two holes for the XLR sockets (G) can be made by drilling a series of small holes around the inside diameters, knocking out the centre pieces and filing for a smooth finish. (watch its orientation) and the 14-pin DIL sockets for IC1, IC2 & IC4. Follow with the low-value ceramic and MKT capacitors, then install the electrolytic and tantalum capacitors. The electrolytics and tantalums are all polarised, so be sure to fit them with correct orientation as shown on Fig.3. Note that both the circuit and overlay depict the use of six 1μF tantalum capacitors. Alternatively, you can substitute 1μF monolithic ceramic capacitors (see parts list). The 12MHz crystal (X1) is next on the list and this goes in just below IC3. It should be fitted with a thin insulat44  Silicon Chip and the USB type B socket. Make sure that the ICs are correctly orientated. ing washer underneath it, so that its metal case cannot make contact with any of the nearby copper tracks on the top of the board (it’s a good idea to fit this even if the PCB has a solder mask). This insulating washer can be made from a small rectangle of clear plastic film, with two small holes punched in it 5mm apart to allow X1’s pins to pass through. Alternatively, you can mount the crystal so that its case is slightly proud of the PCB. The PCB assembly can now be completed by plugging in the three ICs and fitting the three double-RCA sockets If you build this project from a kit, the box and its lid may be supplied pre-drilled and the lid may also come with a screen-printed front panel. If not, then you’ll have to drill and cut the holes in the case yourself. Fig.5 shows the drilling details. Note that holes “B” in the rear panel for the “upper” RCA sockets are 12mm diameter, while holes “A” for the “lower” sockets are 11mm diameter. The reason for this difference is that the larger “B” holes allow easier entry of the lid/PCB assembly into the box, during final assembly. Having drilled, cut and de-burred all of the holes, the next step is to fit the front panel to give the unit a professional finish. Fig.6 shows the front-panel artwork and you can either copy this or download the panel in PDF format from the SILICON CHIP website and print it out. The panel can then be laminated and attached to the lid using double-sided tape. Once it’s in position, cut out the holes using a sharp hobby knife. Final assembly Now for the final assembly. The first step is to fit switch S1, potentiometer VR1 and the two XLR sockets to siliconchip.com.au LINE OUTPUTS LINE INPUTS USB TO HOST S/PDIF IN S/PDIF OUT MICS RECORDING SOURCE SELECT LINE MICROPHONE GAIN LEFT MIC INPUT USB STEREO RECORDING/ PLAYBACK INTERFACE RIGHT MIC INPUT SILICON CHIP Fig.6: this full-size front panel artwork can be copied or you can download it in PDF format from the SILICON CHIP website and print it out. siliconchip.com.au M3 x 20mm SCREWS ATTACH 10mm SPACERS TO LID, ALSO PASS THROUGH THESE SPACERS TO ATTACH 25mm SPACERS BOX LID (FRONT PANEL) (VR1) (S1) S1 the lid assembly. Cut the pot shaft to about 10mm long before fastening it in position. The switch and pot are secured using the supplied nuts, while the XLR sockets are each held in place using a two M3 x 10mm machine screws, star lockwashers and nuts. The next step is to fit extension leads to the terminals of both S1 & VR1. These leads are run using 0.7mm tinned copper wire and should be about 25mm long for S1 and about 35mm long for VR1. That done, sleeve the extension wires with either 1.5mm heatshrink tubing or 2mm varnished cambric tubing. The sleeves for the leads from S1 should be about 18mm long, while those for VR1’s leads should be about 28mm long. The three main connection spigots on the rear of XLR sockets CON1 & CON3 are fitted with similar extension leads. These need to be only about 12mm long, as the sockets extend downwards much further than the switch and pot terminals. They also don’t need any insulating sleeves, as there will be only about 4mm free above the PCB when it is subsequently mounted on the lid. Fig.7 shows how the assembly goes together. Before mounting the board in place, you need to fit four 35mmlong spacers to the holes near the corners of the lid. These spacers are 10mm SPACERS (CON3) 25mm SPACERS SLEEVES ON POT & SWITCH WIRES (CON9) CON5 AND CON6 (PCB) M3 x 6mm SCREWS ATTACH PCB TO 25mm SPACERS NOTE: SMALL COMPONENTS ON PCB OMITTED FOR CLARITY Fig.7: here’s how the assembly fits inside the case. Six wire extensions are required for VR1, six for switch S1 and three each for the XLR sockets. June 2011  45 Parts List 1 double-sided PCB, code 07106111, 109 x 84mm 1 diecast metal box, 119 x 94 x 57mm (Jaycar HB-5064) 1 mini DPDT panel-mount toggle switch (S1) 1 10kΩ 16mm dual pot. (VR1) 1 knob to suit 2 female XLR connectors, panelmount (Jaycar PP-1054, Altronics P 0804) 1 12.000MHz crystal, HC49/4H case (X1) 3 dual RCA sockets, PCB-mount (Jaycar PS-0280, Altronics P 0212) 1 type-B USB socket, PC-mount (Jaycar PS-0920, Altronics P 1304) 3 14-pin DIL IC sockets 4 M3 x 25mm tapped metal spacers 4 M3 x 10mm tapped metal spacers 4 M3 x 20mm machine screws, Phillips head made up using M3 x 25mm and M3 x 10mm tapped metal spacers which are stacked together and secured using M3 x 20mm machine screws. As shown, the screws go through the front panel and initially secure the 10mm spacers in place. The 25mm spacers are then wound on over the protruding ends of the screws. Once the spacers are in position, you’re ready to attach the PCB to the lid. It will be necessary to dress 4 M3 x 10mm machine screws, Phillips head 4 M3 x 6mm machine screws, Phillips head 4 M3 hex nuts 4 M3 star lockwashers 3 4G x 9mm self-tapping screws 1 600mm length of 0.7mm tinned copper wire 1 330mm length of 1.5mm heatshrink tubing 1 200mm length of insulated hook-up wire Semiconductors 3 MCP6024-I/P quad op amps (IC1, IC2, IC4) (from Microchip Direct) 1 PCM2902 stereo audio CODEC (IC3) (from RS Components) 1 REG103GA-A adjustable voltage regulator (REG1) 1 1N5819 Schottky diode (D1) Capacitors 1 100µF 16V RB electrolytic 2 10µF 16V RB electrolytic the leads from S1, VR1 and the XLR sockets so that their ends align with their matching holes in the PCB. It also helps if the various leads have their ends trimmed to staggered lengths, so that they can be guided through in sequence. A pair of long-nose pliers can be used to help guide the leads through their respective holes. If this proves too awkward, remove S1 and potentiometer VR1 from the lid, 2 10µF 16V tantalum 6 1µF 25V monolithic ceramic or tantalum 6 1µF MKT polycarbonate 4 470nF MKT polycarbonate 2 220nF MKT polycarbonate 1 150nF MKT polycarbonate 7 100nF MKT polycarbonate 1 10nF MKT or greencap 4 1nF 50V NPO ceramic 4 820pF 50V NPO ceramic 4 82pF 50V NPO ceramic 3 47pF 50V NPO ceramic 1 39pF 50V NPO ceramic 4 22pF 50V NPO ceramic Resistors (0.25W 1%) 1 1MΩ 4 8.2kΩ 2 220kΩ 2 2.7kΩ 2 150kΩ 1 1.5kΩ 12 100kΩ 1 220Ω 4 33kΩ 1 110Ω 1 27kΩ 6 100Ω 4 15kΩ 2 22Ω 1 13kΩ 1 2.2Ω 12 10kΩ then slip their leads down through the PCB. The lid can then be introduced to the PCB, at the same time guiding the six XLR socket leads through their holes. Once it’s in position, secure the board using four M3 x 6mm machine screws, then slip the switch and pot back up through their mounting holes and do up their nuts. Finally, the leads from the XLR sockets, the pot and the switch can be soldered to the PCB pads and trimmed to length. Earth lead Fig.8: the USB Audio CODEC should become the default device when the USB Stereo Recording & Playback Interface is plugged in (Windows XP dialog boxes). 46  Silicon Chip There’s just one more wiring step to complete the front panel/PCB assembly. This is to fit an insulated “earthing” lead which connects from the PCB earth copper to the body/screen lugs of the XLR connectors. This in turn connects the PCB earth to the metal case when it’s all later screwed together. Fig.3 shows how to install this lead. It’s run using insulated hook-up wire and is connected to the PCB earth copper just to the right of CON9. It then runs across the board to the screen lug of CON3 and then to the screen lug of CON1. That done, the PCB/front panel assembly can be completed by fitting siliconchip.com.au Fig.9: here’s how the interface appears in the “Sound” dialog box (launched via Control Panel) under Windows 7. Fig.10: the USB Audio CODEC should also appear in Device Manager under “Sound, video and game controllers”. the mic gain pot (VR1) with its control knob. The final step in building the project is to slip the PCB/front panel assembly down into the box. This is done by tilting it at an angle so that the RCA connectors can enter their clearance holes in the back of the box. This then allows you to swing down the front of the assembly and lower it all the way into the box. That done, fasten the lid to the box using the four M4 countersink-head screws supplied and use three 4G x 9mm self-tapping screws to secure the three dual RCA sockets to the rear of the case. These self-tapping screws pass through the “C” holes on the rear siliconchip.com.au Fig.11: this scope grab compares the S/PDIF digital audio output from the interface (yellow trace) with the analog audio output waveform (blue trace), when a WAV file is being played back. The timebase here has been slowed down to show the audio waveform clearly. Fig.12: this second scope grab shows the same S/PDIF digital output (yellow) and the analog audio output (blue) but with a much faster timebase speed so you can see the S/PDIF waveform. At this speed the analog waveform appears to be an almost flat horizontal line. panel and ensure that the RCA sockets are not pushed back inside the case when the cables are attached. Don’t over-tighten these screws, otherwise you’ll strip the holes in the plastic bodies of the RCA sockets. Installation & testing Testing involves little more than connecting the unit to a spare USB port on a PC running Windows XP (Service Pack 3), Windows Vista or Windows 7. Alternatively, you can connect it to a spare downstream port on an external USB hub that’s connected to the PC. After a few seconds, you should hear a greeting from the PC’s sound system to indicate that the operating system has recognised that a new Plug and Play USB device has been connected. It then shows pop-ups from the System Tray as it identifies the device and automatically installs the standard USB audio drivers for it. The next step is to check that this has all taken place correctly. In Windows XP, click the Windows Start button, launch the Control Panel and double-click on “Sounds and Audio Devices”. This should bring up the Sounds and Audio Devices Properties dialog. If you then click on the “Audio” tab, you should see “USB Audio CODEC” listed in the drop-down device selection lists for both Sound Playback and Sound Recording (Fig.8). This June 2011  47 Fig.13: Audacity is an excellent freeware program for recording and editing audio files, with versions available for Windows, Apple Macs and Linux systems (from audacity.sourceforge.net). should also be the case if you click on the “Voice” tab. Now click on the “Hardware” tab and select “USB Audio Device”. You should see the following information in the Device Properties area: Manufacturer: (Generic USB Audio) Location: Location 0 (USB Audio CODEC) Device Status: This device is working properly. If you are using Windows 7, launch the Control Panel and double-click on the “Sounds” icon. This brings up the dialog box shown in Fig.9 and you should see that the “USB Audio CODEC” has been installed as the default device. You can also check the device has been correctly installed in Device Manager. Launch Device Manager from Control Panel, then expand the “Sound, video and game controllers” entry and check that “USB Audio CODEC” is listed – see Fig.10. This applies to both Windows XP and Windows 7 (and Vista). lists under both the Audio and Voice tabs of the Sounds and Audio Devices Properties dialog (Windows XP). You can also use the Volume tab to adjust the replay volume and to get Windows to provide a volume control icon in the system tray at the end of the taskbar. Your new USB Stereo Recorder & Playback Interface will now be the default device on your PC for both audio recording and playback. And because it’s fully compatible with all the standard audio drivers built into Windows XP/SP3 and later operating systems, you’ll be able to use it with virtually any of the popular audio recording, editing and playback applications. Even if you don’t have such a suita- Using it Using the unit with your PC for audio recording and playback is straightforward. The first step is to select it as the “Default device” in the drop-down 48  Silicon Chip Fig.14: you can exit the VIA HD Audio Deck applet by right-clicking its icon in the System Tray. ble application installed on your PC at present, there are quite a few available for free downloading on the web. One I can recommend is Audacity which can be downloaded from the Audacity website at audacity.sourceforge. net The current version for Windows XP/SP3 is V1.2.6 but there’s also a beta V1.3.13 that’s described as “the best version for Windows 7 and Vista”. There are also versions for Apple Macs and Linux systems. Via shutdown error Finally, note that with this device connected, you may get a shut-down error on machines with Via sound systems which automatically launch the Via Audio HD Deck applet. You can prevent this by closing this applet before shutting down – just right-click the Via HD Audio Deck icon in the System Tray and click “Exit” (Fig.14). Another option is to prevent the Via HD Audio Deck applet from automatically starting when the PC is booted. That’s done by clicking Start, typing in msconfig, selecting the Startup tab and clearing the relevant check box. Or you can simply ignore the shut-down error and click OK to close the applet SC and force a shut-down. siliconchip.com.au Financial Year End Clearance JUNE 2011 4CH DVR KIT WITH 4 CAMERAS Suited to small surveillance installations in the home or office, this 4 channel DVR can store over 200 hours of video on the internal 320GB HDD. View the recorded video in an indexed event log via a computer or external monitor. Package includes 4 weather resistant IR cameras, 4 x 18m cables, remote control and mains adaptor. 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This camera connects straight to your existing network for complete control. Access the camera through a web interface by hitting the IP address of the device and logging in. The web interface allows you to control the camera around 3-axis, zoom, adjust visual settings, record, take snapshots and setup scheduled recording. 1299 00 199 00 $ • Sensor resolution (H x V pixels): 752 x 582 • Resolution (Horizontal TVL): 550 • Power: 24VAC/12VDC QC-8622 WAS $299.00 NETWORK CONNECT VANDAL PROOF MINI DOME CAMERA 2MP $ High resolution day/night camera with Sony® sensor, colour by day, black and white by night. Extremely high performance in low light levels. Perfect for use with infrared illuminators. High Resolution ExView Colour CCD 2.8" TFT LCD MONITOR & AV RECORDER PROFESSIONAL H.264 DVR RECORDERS High Resolution Day / Night Colour CCD • Flickerless • Sensor: 1/3" Sony® Hi-Res SuperHAD CCD • Resolution (Horizontal TVL): 550 • Power requirements: 24VAC/12VDC QC-8621 WAS $249.00 Note: Carried in limited quantities in major stores only, call before driving across town. QC-8601 WAS $499.00 Note: Carried in limited quantities in major stores only, call before driving across town. QC-8602 WAS $1099.00 8-Ch Professional H.264 DVR with 500GB HDD SAVINGS ON PROFESSIONAL CCD CAMERAS Hikvision 3D PTZ Camera & DVR Control Keyboard Hikvision Outdoor 22x PTZ Camera All Savings are based on Original RRP Limited stock on sale items. This high grade camera is based around the Sony® SS2 vertical double-density wide dynamic range CCD system. It provides a high quality picture in conditions which would render most other cameras useless. See website for complete specifications. • Low smear 00 $ • High anti-blooming • High signal to noise ratio SAVE $50 00 • Mechanical IR cut filter • 470 Horizontal TV lines • Dimensions: 135(L) x 65(W) x 50(H)mm QC-3289 WAS $449.00 399 MINI DVR KIT WITH BUTTON-HOLE CAMERA Capture meetings, conferences or lectures with this high definition video and audio mini DVR kit. Store up to 32GB on an SD card, then allow you to view the video on the 2" TFT LCD screen with different buttonhole options so it's completely covert and discreet. Includes a Li-ion rechargeable battery, charger, AV leads, USB cable and dummy buttons for disguising the camera. 229 00 $ • Approx 10 hours of video • 128MB flash memory $ SAVE 20 00 • Camera resolution: 420TV lines • Windows XP, Vista, 7 compatible • Dimensions: DVR: 65(W) x 54(H) x 14(D)mm Camera: 22(W) x 34(H) x 15(D)mm QC-8006 WAS $249.00 To order call 1800 022 888 Tools For The Trade 46W GOOT 240V SOLDERING IRON NEW TOOLS FOR THE TRADE High quality Japanese made soldering iron with exceptional heat recovery. The ceramic heater is automatically controlled by the heating load of the tip. With its high insulation and low current leakage, soldering of precision flat ICs and CMOS is safe. The heater on/off control uses a zero-volt switch circuit which reduces noise. Spot Face Cutter for Strip Boards • Tip temperature is set at 320°C • The power lead is made from flexible silicone rubber • The handle incorporates a ribbed rubber piece for superior grip • Electricity Safety Approval Number SAITE20185 95 $ TS-1430 Spiral Drive Drill/Driver Designed to neatly remove copper track on strip type prototyping boards. Insert the tool in the pre-drilled hole and rotate it until the track is removed entirely. Easy to use and efficient. Spiral driven drill/driver is ideal for very fine work. Push the handle to rotate the collet slowly. Add drill bit or screwdriver bit. Comes with 2 pin vice collects and 3 small drill bits. • Length: 110mm • Handle measures: 60(L) x 17(W) x 17(D)mm TD-2461 • Measures: 180(L) x 15(Dia)mm overall (uncompressed) TD-2089 8 $ 95 16 95 $ Stainless Steel Tweezer Set - ESD safe Set of 3 tweezers, duckbill head, angle fine and straight superfine. ESD coating to reduce static discharge. 79 • Measures: Angled & duckbill 120mm, superfine 135mm TH-1760 Spare tips available: 0.5mm Tip (as supplied with iron) TS-1432 $19.95 0.3mm Tip TS-1434 $19.95 0.3mm Chisel Tip TS-1436 $19.95 Over 500 pages NEW exciting products 19 95 $ High Quality Iron Grab a copy now! MR16 HALOGEN GLOBES PRO SOUND LEVEL METER WITH CALIBRATOR Low voltage, high brightness halogen lights used as general lighting around the house or shops, automotive and camping use. Suitable where accuracy, repeatability and validation is required. Ideal for vehicle noise testing, race scrutineering, traffic/aircraft noise or any evidencebased noise testing. Conforms to IEC 61672-1 Class 2 for sound level meters. Calibrator included. Voltage Angle Cat no. 12V 12V 12V 12V 24V 30o 38o 12o 38o 38o SL-2733 SL-2730 SL-2731 SL-2732 SL-2745 Was Now Save $7.45 $7.45 $7.45 $7.45 $8.95 $2.95 $2.95 $2.95 $2.95 $2.95 $4.50 $4.50 $4.50 $4.50 $6.00 BUY BULK AND SAVE • Backlit LCD • Analogue outputs • Dimensions: 278(L) x 76(W) x 50(D)mm $ QM-1592 WAS $399.00 Buy 5 for $10 SAVE 100 Ideal for audio enthusiasts designing their own crossovers. Features large digits and 30minute auto power off. Supplied with Carry case and K-type probe with curly cord. See website for full specifications. All the tools you need for cutting, stripping and crimping F-connectors for coax cable installations. MICRO ENGRAVER Kit includes: • Coax cable stripper • Compression crimp tool • Heavy duty cable cutter • 10 x F-59 plugs • Nylon storage case: 152(W) x 220(H) x 45(D)mm TH-1804 WAS $79.95 39 95 $ • Display: 2000 count SAVE $5 00 • Transistor Test • Dimensions: 194(H) x 91(W) x 44(D)mm QM-1324 WAS $44.95 This screwdriver has a rotary magazine that stores the bits. When a different bit is required, rotate the magazine, pump the reloading action and the new bit is inserted into the ratchet head ready to go. The handle stores 4 reserve bits and 8 other bits are included, but you can add any 4mm hex drive bit if needed. F-CONNECTOR TOOL SET 00 INDUCTANCE /CAPACITANCE / FREQUENCY DMM 10-IN-1 ROTARY PUMP-ACTION SCREWDRIVER • PH: 00, 0, 1, 2 • Slotted: 1.5, 2, 3 • Torx: T5, T6, T8, T10 • Dimensions: 168(L) x 26(Dia)mm TD-2108 Save over 50% 299 00 $ 2011 Engineering Catalogue Out Now! 9 $ 95 DEAL Buy 2 for $15 SAVE $4.90 Engrave your valuables for security or insurance. The tiny diamond coated tip spins at 10,000 RPM so you can personalise tools, sporting gear, toys, security ID on valuables etc. Engraves glass, ceramics, metals and plastics. Batteries and case included. Tip is replaceable. 39 $ 95 SAVE $40 00 • Size: 160(L) x 15(Dia)mm TD-2468 19 95 $ Replacement tip sold separately TD-2469 $6.95 HANDY SERVICE AIDS Isopropyl Alcohol Super Glue Debonder Uses as a head cleaner, surface cleaning and prep, contact cleaning, stain removal in the laundry etc. Also a medical-grade surface disinfectant. Dries quickly and is relatively non-toxic. 50% concentration. A choice of two sizes: Super glue is tenacious in sticking skin together, and has been exploited as an alternative to surgical sutures. Debonder will quickly and painlessly separate skin stuck with super glue. NA-1062 WAS $2.50 NOW $1.50 SAVE $1.00 • 20ml bottle with applicator NA-1501 20ml Spray 200ml Bottle NA-1064 WAS $6.95 NOW $4.95 SAVE $2.00 FROM 1 $ 50 Cordon off hazardous areas or create an unmistakable marker with this heavy duty PVC tape. The vivid colouring will draw anyone's attention to the barrier. • 33m roll 1 $ 95 DEAL www.jaycar.com.au Heavy-duty PVC Tape Buy 2 for $3 DEAL Buy 2 for $15 Two colours available: Red/White NM-2864 WAS $15.95 NOW $9.95 SAVE $6.00 Yellow/Black NM-2866 WAS $15.95 NOW $9.95 SAVE $6.00 DeoxIT ProGold Contact Cleaner & Rejuvenator - Pen Style This product will not only clean, but it will help restore your equipment to its original condition, and improve its performance. NS-1430 19 95 $ Also available DeoxIT Contact Cleaner & Rejuvenator Aerosol NS-1434 $24.95 DeoxIT Contact Cleaner & Rejuvenator Solution Kit NS-1436 $24.95 Limited stock on sale items. All Savings are based on Original RRP 3 Sight & Sound MUSIC CENTRES Digital CD/USB/SD Encoding Music Box WITH Clock & AM/FM Radio 3 Speed Turntable with Speakers & Audio Output Listen to vinyl collections directly from the unit and its built-in speakers or use the line level output to listen on an external amplifier. Features a 3.5mm headphone jack for personal listening with adjustable bass control. Great for the family home or apartment. 79 00 $ • 33/45/78 RPM • Stereo amplifier • Automatic stop • 45 RPM adaptor • Mains powered • Dimensions: 35(L) x 31(D) x 13(H)mm GE-4136 The music box allows you to record your CD collection straight to SD card or memory stick. Records directly from USB drive to SD card or vice versa. This modern & user friendly design features a crystal clear AM/FM digital tuner, blue back light LCD, alarm clock with sleep & snooze function. Wake up to your choice of radio, buzzer, CD or favourite songs stored on SD card or memory stick. Features battery back up, protects your settings in case of a power failure. • CD / CD-R, RW / MP3-CD playback • Repeat one / All / Program / Random play • Store up to 40 stations • Built-in amplifier and stereo speakers • AUX in & Headphone output • Requires 2 x AAA batteries • Dimensions: 250(W) x 00 $ 204(D) x 85(H)mm GE-4138 USB Cassette Deck with PC Encoder Record cassette tracks to your computer via USB or play back through the built-in 5W speaker. You can also run the line level outputs to an external amplifier and use it as a component cassette deck. • Dimensions: 178(L) x 72(H) x 178(W)mm GE-4054 WAS $79.95 59 95 $ SAVE $20 00 99 5.8GHZ WIRELESS AV SENDER 5" SPEAKERS WITH USB Send audio and video signals right round the house from practically any video source - DVD, VHS, set-top box, cable TV etc. Operating on the 5.8GHz band keeps it free from interference on the 2.4GHz band and an external omnidirectional antenna provides a transmission range of up to 100 metres. 00 $ AR-1880 WAS $89.00 The built-in amp provides 30WRMS per channel. Input is either via linelevel RCA or USB, so it will accept memory sticks or any other USB device. Add an MP3 player for a complete digital music system. It also has bass, treble, volume and MP3 track controls on the back panel. Perfect for your next patio party. Extra receiver available AR-1881 • Mounting brackets included • Dimensions: 180(W) x 235(H) x 180(D)mm CS-2437 74 SAVE $15 00 WAS $64.95 NOW $39.95 SAVE $25.00 PLASMA/LED/LCD FULL MOTION WALL BRACKET 109 00 • Accommodates TVs from 23 to 37" up to 45kg. CW-2829 COMMUTER SPECIAL Portable DAB+/FM Radio with Earphones An ultra-compact DAB+ radio that is small enough to fit in a pocket. Never miss your favourite radio stations while on the go. Provides excellent reception and crystal clear digital sound. Runs on 2 x AAA batteries (not included), it is also equipped with a standard FM radio. 99 $ 00 Note: DAB+ not available in all areas. AR-1754 Better, More Technical 4 Active VGA + Audio to HDMI Converter This converter box takes the VGA output + stereo audio signal from your PC, and converts them to now common HDMI format whilst maintaining full high-definition resolution. Mains adaptor included. • Dimensions: 90(L) x 68(W) x 25(H)mm AC-1609 WAS $129.00 Also available: 199 00 $ Sold as a Pair Provides full motion off the wall. The 620mm extension arm gives a range of rotation of 180° and tilt of -12°, so it is ideal for mounting in the corner of a room, or mounting the TV in an otherwise awkward and unviewable position. Also allows for ±2° lateral roll to ensure the $ TV is perfectly level after installation. • Earphones included • Dimensions: 68(L) x 38(W) x 21(H)mm VIDEO/AUDIO CONVERSION DEVICES Ideal for enhancing fringe mobile phone reception or 3G Internet performance for a farm or a boat. It provides a very handy 7dBi of gain in any direction. Made from fibreglass and supported by an aluminium support piece and two sturdy clamps. • Frequency range:800/900/1800/1900/2100MHz • Overall antenna length 1.05m approx. AR-3313 HDMI to VGA/Component and LR Analogue Audio Converter AC-1605 WAS $149.00 NOW $129.00 SAVE $20.00 Converts digital audio from either coax or Toslink inputs and outputs to Toslink or coax. It has a built-in amplification feature: it can serve as a repeater of audio signals and extend (double) the transmitting distance. 49 95 $ • Dimension: 42(W) x 40(D) x 22(H)mm AC-1601 WAS $59.95 SAVE $10 00 Digital to Analogue Audio Converter Converts your digital audio from either a coax or optical source to a standard analogue left and right RCA output. Useful for connecting DVD/Blu-Ray players to displays or audio equipment that have a no digital audio input. 99 00 $ • Dimensions: 42(W) x 40.5(D) x 22(H)mm $ AC-1603 WAS $69.95 59 95 High Quality Lightweight Stereo Headphones Ultra-lightweight stereo headphones that provide outstanding performance and comfort. Featuring high output drivers, they produce crystal clear sound with crisp highs and smooth bass response. Soft leatherette swivel ear pads, adjustable headset and 1.2m lead. AA-2061 All Savings are based on Original RRP Also available: SAVE $10 00 Analogue to Digital Audio Converter AC-1611 WAS $79.95 NOW $59.95 SAVE $20.00 BLACK MAINS EXTENSION LEAD Perfect for stage, lighting, DJ or other applications where the inconspicuousness of a black extension lead is required. Rated to 10A max. 24 95 $ Buy both for $110 Save $13.95 Limited stock on sale items. SAVE $30 00 Digital Toslink/Coax Audio Converter OMNI-DIRECTIONAL MAST ANTENNA - 3G CELLULAR DEAL 99 00 $ 2m PS-4152 $5.95 5m PS-4155 $9.95 10m PS-4157 $14.95 To order call 1800 022 888 Power MONITOR POWER & SAVE Remote Controlled 240V Mains Outlets Wireless 3-Outlet Mains Power Meter Simply plug an appliance into each sender unit, enter local electricity price and monitor the usage on the LCD receiver unit. Also monitors the cumulative usage via the memory as well as the greenhouse gas emissions. Switch any mains appliance rated up to 10A on or off remotely. Control up to three separate devices and switch them individually. Includes 3 mains outlets and 1 remote control. • Transmission range: 30m • Frequency: 433.92MHz • Remote size: 100(L) x 35(W) x 20(H)mm MS-6140 WAS $39.95 69 95 $ • Transmission range: 30m • Receiver requires 3 x AA batteries SAVE $30 00 • Clock and alarm function • Dimensions: Sender: 58(W) x 125(H) x 48mm Receiver: 100(W) x 130(H) x 36(D)mm MS-6116 WAS $99.95 150W LAPTOP POWER SUPPLY 15-24VDC Specifically $ designed for use with laptop computers. Features short circuit and overload protection, an LED power indicator and USB output for charging USB devices. Comes with 9 different DC adaptors that suit most laptop computers on the market. 119 00 • Input voltage: 100-240VAC 50/60Hz • 7 Selectable DC voltages • Dimensions: 63(W) x 180(D) x 40(H)mm MP-3471 29 95 $ SAVE $10 00 3-STAGE 48V 9A BATTERY CHARGER SOLAR RECHARGEABLE LED SPOTLIGHT RECHARGEABLE 35W HID SPOTLIGHT Compact and lightweight. Suitable for golf buggies, electric wheelchairs or similar applications. It monitors and manages your charging with three different stages and will MASSIVE maintain the optimum charge SAVINGS!!! level. Cables included. Perfect for your car, boat, workshop, camping or fishing trip. It has a dual position swivel handle for maximum versatility and a high tech solar panel so it can be charged at all times. Ideally suited to search and rescue, boating, professional shooters, security or other high-power applications. Housed in a tough weather-resistant ABS housing with shoulder strap for extended use. The built-in rechargeable battery gives about 50 minutes of continuous use and it recharges either from the mains plugpack or a car cigarette lighter socket. • Short circuit, output current, 00 $ polarity and thermal protection • LED charge status indication SAVE $100 00 • Digital Charge Display • Dimensions: 298(D) x 112(W) x 60(H)mm MB-3628 WAS $499.00 399 4 WAY POWERBOARD WITH FILTER / SURGE AND OVERLOAD PROTECTION Guard your expensive HiFi, TV, or VCR etc. against damage. This powerboard offers 4 outlets, all filtered and surge protected. Black in colour. • 4 Surge and Spike protected mains outlets • 10 amp resettable overload circuit breaker • Power on indicator in switch • Approval Number : N17298 • Cable length: 1 metre MS-4057 14 $ 95 LED LIGHT LANTERN WITH SOLAR CHARGER PSU ADAPTOR A super bright white LED lamp with an integrated compass. Can be charged via included mains power, car charger or by the unit's 2.5W solar panel. • Included 2.5Ah/6V battery • Lamp measures: 250(H) x108(Dia)mm ST-3128 WAS $99.95 SAVE 40 39 95 $ • Output: 3300 lumens • Power: 35W • Dimensions: 300(L) x 210(Dia)mm ST-3369 WAS $149.00 Deep-cycle gel performance for solar installations and other alternative energy systems. • Capacity: 200Ah (20hr. rate) • Initial charge current: 30A • Cycle voltage: 14.4 - 15V • Standby voltage: 13.5 - 13.8V • Dimensions: 523(L) x 239(W) x 223(H)mm • Weight: 62kg SB-1697 00 CREE® XP-G HIGH POWER LED 129 00 $ SAVE $20 00 Spare globe available: ST-3363 WAS $39.95 NOW $29.95 SAVE $10.00 12V 200AH DEEP CYCLE GEL BATTERY 260 LUMEN RECHARGEABLE CREE® LED TORCH This torch outputs 260 lumens of white light from a battery that is slightly larger than a single AA. Great for every day activities and more demanding uses such as hiking or caving adventures. 69 799 00 $ Note: Not stocked in all stores but can be ordered. Call your nearest store for details. RECREATIONAL SOLAR KITS Clean renewable energy wherever you go. Convert your 4WD or caravan to generate sufficient power to operate several appliances - 12V camping essentials and luxuries etc. Just add a battery for a selfsustained setup. Two versions to choose from. 80W Standard Package 59 95 $ $ • 140 Lumens • Solar cell, car cigarette lighter and mains chargers included • Detachable weatherproof solar station • Size approx: 175(L) x 120(W) x 150(H)mm ST-3312 • 1 x 80W monocrystalline solar panel ZM-9097 • 1 x 12V 6A charge controller MP-3128 • 2 x female PV connector PS-5100 $ • 2 x male PV connector PP-5102 ZM-9300 WAS $450.00 The XP-G series offers world leading lumen output and efficiency. They can deliver over 150 lumens for cool white, and over 110 lumens for warm white. A fantastic solution to lighting where limited power is available. With a life expectancy of over 50,000 hours, and you have a lighting solution that is truly hard to beat. Lens sold separately. 425 • Burn time: 5 hrs 95 $ • Includes one rechargeable 3.7V 2200mAh Li-ion battery • Mains charger included • Dimensions: 205(H) x 45(W)mm ST-3453 160W Advanced Package • 2 x 80W monocrystalline solar panel ZM-9097 • 1 x 12V 20A charge controller MP-3126 • 3 x female PV connector PS-5100 • 3 x male PV connector PP-5102 • 1 x solar panel Y-lead 2 socket to 1 plug PS-5110 • 1 x solar panel Y-lead 2 plug to 1 socket PS-5112 ZM-9302 WAS $900.00 850 00 $ 00 SAVE $25 00 SAVE $50 00 White ZD-0445 $17.95 Warm White ZD-0447 $19.95 stock on sale items. Limited stock on sale items. www.jaycar.com.au Limited 5 Automotive UNIVERSAL USB MOBILE PHONE CAR CHARGER FLEXIBLE STRIP LED LIGHTING These low voltage (12VDC) LED light strips are perfect for edge-lighting or to illuminate signs, window displays and other small lighting applications. The LEDs are mounted on a flexible printed circuit board with a no-fuss, no mess 3M adhesive backing. The strip is sold cut-to-length in 50mm segments or a continuous length up to 5m. Each 50mm segment has 3 LEDs and requires 12VDC<at>16mA. Various colours available. • Sold cut-to-length in 50mm segments • 3 LEDs per segment • 3 LED segment dimensions: 50(L) x 8(W) x 0.25(D)mm White Warm White Red Blue BUDGET RESPONSE CAR SPEAKERS The handy solution to charge your mobile phone in the car. Included is a cigarette lighter USB car charger capable of delivering 5VDC up to 1A via the USB output, as well as a universal USB charging lead with 9 interchangeable tips to match all the most common mobile phones. See website for compatible phones and plugs. 19 95 $ 3 Per segment 5" Coax 2 Way Car Speakers REAR VIEW MIRROR TFT MONITOR WITH CAMERA ZD-0473 ZD-0487 ZD-0475 ZD-0479 A complete rear-view safety package including a 7" TFT LCD monitor and a flush mount weatherproof camera. It has adjustable spring-loaded brackets to fit different sized mirrors. Composite video input. Includes slimline remote control, 5-metre video/power cable and 28mm holesaw for camera mounting. SUBWOOFERS Twin Port Subwoofer Enclosures 179 00 • 7 inch screen • Mirror Dimensions: 260(L) x 108(H) x 50(D)mm QM-3762 WAS $249.00 Dual ported subwoofer enclosures with black carpet covering. Designed for optimal performance with the Vifa 10" subwoofers (below) . All you need to do is to add the driver of your choice. $ SAVE $70 00 Note: Should not be used as a substitute for a conventional rearview mirror but ideal when view is blocked by trailer or caravan. • Dimensions: 480(W) x 360(H) x 280(D)mm 4" Coax 2 Way Car Speakers Power handling: 15WRMS Nominal impedance: 4 ohms Frequency response: 90Hz - 18kHz Sensitivity: 83dB SPL 1W<at>1m CS-2310 WAS $24.95 NOW $19.95 SAVE $5.00 • Input: 12 - 24VDC • Output: 5VDC, 1.0A MP-3578 $ 95 Low cost doesn't mean low quality. Coax speakers are an ideal replacement for the standard equipment stereo speakers you get in the average car. All are equipped with titanium coated fibre woofers and silk dome tweeters for smooth high frequency response. Power handling: 15WRMS Nominal impedance: 4 ohms Frequency response: 70Hz - 18kHz Sensitivity: 85dB SPL 1W<at>1m CS-2312 WAS $29.95 NOW $24.95 SAVE $5.00 19 95 $ 6" Coax 2 Way Car Speakers Power handling: 22WRMS Nominal impedance: 4 ohms Frequency response: 60Hz - 20kHz Sensitivity: 88dB SPL 1W<at>1m CS-2314 WAS $34.95 NOW $29.95 SAVE $5.00 6 x 9" Coax 2 Way Car Speakers Note: Vifa driver not included CS-2526 Power handling: 27WRMS Nominal impedance: 4 ohms Frequency response: 55Hz - 18kHz Sensitivity: 86dB SPL 1W<at>1m CS-2316 WAS $44.95 NOW $39.95 SAVE $5.00 DEAL Buy both for $210 SAVE $78.95 Vifa 10" Subwoofer 39 95 $ CAR STEREO LINE ISOLATION TRANSFORMER Produce high quality sound. With dual voice coils, high power handling and die-cast aluminium chassis, they don't just deliver brilliant low-register bass clarity but also thump tremendous SPLs like only Vifa speakers can. AUTOMOTIVE 8-WAY PLUG/SOCKET - 250 SERIES This transformer coupled network will remove any Ground Loops in your car stereo. There is absolutely no attenuation when the unit is connected. Supplied with gold RCA plugs and sockets for low level inline connection. $ • 200WRMS <at> 2 x 4 ohms CS-2351 00 $ WAS $249.00 199 Used in automotive applications such as stereo and CB installations, or for replacements in existing wiring. • Comes with plug, socket, and male and female locking spade lugs PP-2069 12 75 • Freq resp: 20 to 20kHz • No power required AA-3085 WAS $19.75 SAVE $50 00 6 $ 95 SAVE $7 00 Buy a Giftcard Today! RESPONSE PRECISION CAR AMPLIFIERS With improved heat sinks and upgraded low-profile chassis design, each model delivers surprising grunt and performance in a sleek and compact package that fits neatly under a car seat. All include gold plated power and speaker terminals and variable low pass filters. Our class AB amps come with variable high pass filters and pass through RCAs; while our class D subwoofer amps feature variable subsonic filter, phase shift and master/slave operation. 2 x 80WRMS Class AB Amplifier Dimensions: 266(L) x 235(W) x 58(D)mm AA-0450 WAS $149.00 NOW $129.00 SAVE $20.00 4 x 50WRMS Class AB Amplifier Dimensions: 316(L) x 235(W) x 58(D)mm AA-0451 WAS $199.00 NOW $169.00 SAVE $30.00 2 x 150WRMS Class AB Amplifier Dimensions: 376(L) x 235(W) x 58(D)mm AA-0452 WAS $229.00 NOW $199.00 SAVE $30.00 4 x 100WRMS Class AB Amplifier Dimensions: 436(L) x 235(W) x 58(D)mm AA-0453 WAS $299.00 NOW $249.00 SAVE $50.00 500WRMS Linkable Class D Subwoofer Amplifier MACHINED BRASS BUSBAR - 8 WAY FROM Dimensions: 232(L) x $ 178(W) x 58(D)mm AA-0454 WAS $249.00 NOW $219.00 SAVE $30.00 129 00 AA-0450 Dimensions: 306(L) x 178(W) x 58(D)mm AA-0455 WAS $369.00 NOW $329.00 SAVE $40.00 AA-0455 All Savings are based on Original RRP Limited stock on sale items. Machined brass busbar used to give electrical common point for wiring, also useful for low voltage tie points such as on boats, RVs or caravans. Conservative insulation rating of 1000V. • All screws M4.0 Brass bar 9.0 x 6.0 • Length overall including standoffs: 100mm, without standoffs: 65mm. SZ-2003 1000WRMS Linkable Class D Subwoofer Amplifier Better, More Technical 6 FROM 6 $ 95 To order call 1800 022 888 Kits KITS FOR KIDS 8-in-1 Solar Educational Kit Your kids will love constructing one of 8 scientific kits that will not only keep them occupied for hours but they will also learn about solar technology. No tools, soldering or glue required. The finished projects are solar powered, but can also be powered by a 50W halogen light. Each project is easy and fun to build with a detailed instruction manual included. • Projects: car, riverboat, octopus, spaceship, solar LED, robot, windmill, space alien • Adjustable solar panel • Suitable for ages 8+ • Solar panel dimensions: 60(L) x 35(W)mm KJ-8925 39 95 ”ALL TERRAIN” Multi Function Tracked Robot Wind Powered Eco-biker Very robust all terrain multi function tracked robot kit - very detailed instruction manual to help you put this kit together. Comes with 6 terrestrial tracks/crawlers. Can be reconfigured to operate as a gripper, rover or forklift type mechanism. Electric motors included. • Batteries AA x 4 (not included) • Dimensions of gripper robot: 90(H) x 160(W) x 270(L)mm KJ-8918 • Total rider/assembly: 125(H) x 100(L) x 90(W)mm KJ-8923 49 95 $ $ FLICKERING FLAME LIGHTING Refer: Silicon Chip Magazine November 2009 Avoid unnecessary noise and vibration in twinengine boats. The Engine Speed Equaliser Kit takes the tacho signals from each motor and displays the output on a meter that is centred when both motors are running at the same RPM. When there's a mismatch, the meter shows which motor is running faster and by how much. Simply adjust the throttles to suit. Short form kit only, requires moving coil panel meter (QP5010). Refer: Silicon Chip Magazine October 1997 This lighting effect uses a single 20 watt halogen lamp (the same as those used for domestic down lights) to mimic its namesake. Mounted on a compact PCB, it operates from 12VDC and uses just a handful of readily available components. Use it for stage performances or for unique lighting effects at home. • Kit includes 20W halogen lamp, PCB plus electronic components $ • PCB: 38 x 58mm KC-5234 39 95 16 95 $ SECURITY KITS UHF Rolling Code Remote Switch Kit Refer: Silicon Chip Magazine August/September 2009 High-security 3-channel remote control that can be used for keyless entry into residential or commercial premises or for controlling garage doors and lights. Features rolling code / code hopping, the access codes can't be intercepted and decoded by undesirables. The transmitter kit includes a three button key fob case and runs on a 12V remote control battery. The receiver is a short-form kit without case so you can mount it in the location or enclosure of your choice. • Receiver 12VDC <at> 150mA (1A for door strike use) • Additional Transmitter Kit available KC-5484 $39.95 • PCB: Transmitter: 34 x 56mm $ • Receiver: 110 x 141mm KC-5483 99 95 Rolling Code Infrared Keyless Entry System Refer: Silicon Chip Magazine October 2007 This keyless entry system features two independent door strike outputs and will recognise up to 16 separate key fobs. The system keeps the coded key fobs synchronised to the receiver and compensates for random button presses while the fobs are out of range. Supplied with solder masked and silk screen printed PCB, two programmed micros, battery and all electronic components. • Receiver requires a 12VDC 1.5A power supply • Some SMD soldering is required • PCB: 61 x 122mm KC-5458 64 95 $ www.jaycar.com.au BRIDGE MODE ADAPTOR FOR STEREO AMPLIFIERS Refer: Silicon Chip Magazine July 2008 Enables you to run a stereo amplifier in 'Bridged Mode' to effectively double the power available to drive a single speaker. There are no modifications required on the amplifier and the signal processing is done by this clever kit. Requires balanced (+/-) 15-60V power supply. • Supplied with silk screened PCB and components • PCB: 103 x 85mm KC-5469 19 95 $ Salt Water Fuel Cell Powered Car MARINE ENGINE SPEED EQUALISER KIT • 12VDC • PCB: 105 x 63mm KC-5488 This cute little kit assembles up into a wind turbine powered model bicycle rider. The wind turbine operates the rider's arms, legs and body. If the wind is strong enough it generates enough electricity to run the bikes LED headlight! The assembled unit is designed to mount in the neck of a soft-drink bottle or - appropriately on the handlebars of a bicycle. Mounting parts included. 27 95 $ VOLTAGE MODIFIER KIT FOR CARS Refer: Silicon Chip Magazine December 2009 This kit intercepts and alters the signal from engine sensors that supply a voltage signal to the engine control unit (ECU). Restore correct air/fuel ratios after engine modifications, prevent engine boost cuts or alter sensor signals for improved driveability. Requires hand controller for programming, RS-232 cable and a suitable input signal. • Includes PCB, case and electronic components • 12VDC • PCB: 87 x 105mm KC-5490 This car uses a simple, environmentally friendly fuel cell to power small electric car for hours of very safe fun. All that you have to add is water and table salt! Comes as a self-assembly kit. Includes 3 fuel cell sheets, non woven fabric separator and air cathode. • Suitable for ages 8+ • Car measures: 75(L) x 40(W) x 18(H) mm KJ-8921 19 95 $ SLA BATTERY HEALTH CHECKER KIT Refer: Silicon Chip Magazine August 2009 Checks the health of SLA batteries prior to charging or zapping with a simple LED condition indication of fair, poor, good etc. • Overlay PCB and electronic components • Case with machined and silk-screened front panel • PCB: 185 x 101mm KC-5482 79 95 $ ULTRASONIC ANTIFOULING FOR BOATS Refer: Silicon Chip Magazine September/October 2010 Marine growth electronic antifouling systems can cost thousands. This project uses the same ultrasonic waveforms and virtually identical ultrasonic transducers mounted in sturdy polyurethane housings. By building yourself (which includes some potting) you save a fortune! Standard unit consists of control electronic kit and case, ultrasonic transducer, potting and gluing components and housings. The single transducer design of this kit is suitable for boats up to 10m (32ft); boats longer than about 14m will need two transducers and drivers. Basically all parts supplied in the project kit including wiring. (Price includes epoxies). • 12VDC 00 $ • Suitable for power or sail • Could be powered by a solar panel/ wind generator • PCB: 78 x 104mm KC-5498 249 79 95 $ Limited stock on sale items. 7 Clearance Sale BUY NOW SAVE $$$ Over 20 to 75% off all listed items Listed below are a number of discontinued items that we can no longer afford to hold stock. We need space in our stores! You can get most of these items from your local store but we can not guarantee this. Please ring your local store to check stock. At these prices we won’t be able to ship from store to store. ITEMS WILL SELL FAST AND STOCK IS LIMITED. ACT NOW TO AVOID DISSAPOINTMENT. Sorry NO RAINCHECKS. Product Description Cat No Original Special Save RRP $ Price $ $ Product Description Cat No Original Special Save RRP $ Price $ $ Remote Command-A-Man Talking Swear Box USB Keyboard with Rhinestones Voice Recorder Digital 2GB GT-3170 GH-1316 GH-1899 XC-0382 $9.95 $19.95 $59.95 $129.00 $1.00 $8.95 $29.95 $80.00 $8.95 $11.00 $30.00 $49.00 SL-3212 MP-3071 SL-2810 SL-2741 SL-2729 SL-2737 ST-3288 MB-3672 ST-3007 ST-3006 ST-3886 SL-3153 SL-2974 ZM-9080 SL-2816 MS-6138 PS-4044 MP-4552 MP-4554 MP-4551 ST-3308 SL-2716 MP-3232 ST-3331 ST-3389 ST-3384 ST-3178 $1.20 $9.95 $1.75 $7.95 $7.45 $8.95 $34.95 $99.95 $16.95 $39.95 $19.95 $22.95 $58.95 $99.00 $6.95 $29.95 $6.95 $219.00 $499.00 $189.00 $89.95 $149.00 $23.95 $14.95 $9.95 $4.50 $29.95 $0.07 $4.95 $0.50 $2.50 $1.95 $2.50 $17.95 $34.95 $9.95 $22.95 $10.00 $7.95 $34.95 $30.00 $2.95 $11.95 $2.95 $134.00 $359.00 $89.00 $62.95 $89.00 $6.95 $13.95 $5.95 $1.50 $8.95 $1.13 $5.00 $1.25 $5.45 $5.50 $6.45 $17.00 $65.00 $7.00 $17.00 $9.95 $15.00 $24.00 $69.00 $4.00 $18.00 $4.00 $85.00 $140.00 $100.00 $27.00 $60.00 $17.00 $1.00 $4.00 $3.00 $21.00 QV-8000 LA-5134 LA-5556 LA-5512 LA-5484 LA-5532 LA-5520 LA-5488 QC-3467 QC-3472 QC-3498 QC-3291 QC-3297 QC-3503 QC-3474 QC-3727 QC-3310 QC-3309 QC-3300 QC-3307 QC-3571 LA-5312 QC-8615 QC-3502 QC-8001 QV-3094 LA-9020 LA-5123 LA-5309 LA-5307 QC-3446 $69.00 $89.95 $23.95 $449.00 $599.00 $59.95 $199.00 $999.00 $99.00 $89.00 $279.00 $89.00 $299.00 $249.00 $69.00 $249.00 $109.00 $179.00 $199.00 $299.00 $179.00 $29.95 $39.95 $599.00 $149.00 $349.00 $59.95 $169.00 $29.95 $199.00 $169.00 $45.00 $39.95 $21.95 $404.00 $539.00 $54.95 $179.00 $899.00 $62.00 $28.00 $116.00 $53.00 $197.00 $89.00 $44.00 $134.00 $45.00 $71.00 $89.00 $134.00 $62.00 $7.95 $34.95 $449.00 $80.00 $134.00 $54.95 $50.00 $9.95 $70.00 $53.00 $24.00 $50.00 $2.00 $45.00 $60.00 $5.00 $20.00 $100.00 $37.00 $61.00 $163.00 $36.00 $102.00 $160.00 $25.00 $115.00 $64.00 $108.00 $110.00 $165.00 $117.00 $22.00 $5.00 $150.00 $69.00 $215.00 $5.00 $119.00 $20.00 $129.00 $116.00 Audio/Video Products Antenna - 2.4GHz Ceiling-Mount Antenna - 2.4GHz Compact Yagi 8dB Gain Antenna - 2.4GHz Wall-Mount Panel Antenna - 3.5GHz Flat Panel 12dB with Bracket Audio Video Module 2.4GHz - Transmitter AV Sender/Receiver 2.4GHz Clip-on Chromatic Tuners DAB+ & FM Radio Tuner Compact DAB+ Digital Radio Dual HD DVB TV Tuner and Recorder with HDMI HDMI Cable 1.8m Bargain HDMI Extender/Repeater HDMI In-Line Repeater/Extender HDMI Wall Plate Socket Double Headphone 2.4GHz Wireless with USB Transmitter High Definition Digital TV Set-Top Box Micro USB Digital Tuner Shielded VHF UHF Diplexer for Digital TV Speaker 12" Foldback Speaker Selector 8 Way with Impedance Matching Video Distribution Amplifier 4 Output Video Distribution Amplifier Dual Output Video Splitter - Two Output Video Transmitter - Long Range AR-3271 AR-3272 AR-3275 AR-3274 QC-3598 AR-1836 AA-2041 AR-1751 AR-1750 XC-4918 WQ-7414 AC-1697 AC-1698 PS-0286 AA-2035 XC-4916 XC-4897 LT-3080 CS-2516 AC-1682 QC-3439 QC-3438 QC-3435 QC-3425 $49.95 $99.00 $89.95 $119.95 $19.95 $76.95 $14.95 $89.00 $139.00 $399.00 $9.95 $54.95 $79.95 $29.95 $99.95 $99.00 $89.95 $69.95 $169.00 $199.00 $119.00 $89.00 $59.95 $179.00 $12.95 $89.00 $22.95 $43.95 $7.95 $34.95 $8.95 $67.00 $67.00 $359.00 $3.95 $21.95 $24.95 $9.95 $49.00 $80.00 $71.95 $34.95 $116.00 $134.00 $80.00 $35.00 $24.95 $49.00 $37.00 $10.00 $67.00 $76.00 $12.00 $42.00 $6.00 $22.00 $72.00 $40.00 $6.00 $33.00 $55.00 $20.00 $50.95 $19.00 $18.00 $35.00 $53.00 $65.00 $39.00 $54.00 $35.00 $130.00 AX-3684 AR-1862 MB-3503 MB-3546 LT-3051 SL-2719 QM-3787 LR-8869 CS-2397 CS-2399 AX-3530 AX-3542 AS-3024 CT-1934 AR-1854 $24.95 $69.95 $37.95 $19.95 $9.95 $1.65 $385.00 $149.00 $189.00 $199.00 $1.95 $4.70 $6.95 $29.95 $69.95 $22.95 $64.95 $17.95 $9.95 $2.95 $0.45 $179.00 $134.00 $134.00 $170.00 $0.45 $1.30 $1.95 $18.95 $22.95 $2.00 $5.00 $20.00 $10.00 $7.00 $1.20 $206.00 $15.00 $55.00 $29.00 $1.50 $3.40 $5.00 $11.00 $47.00 DC-1500 GH-1118 GG-2307 GH-1871 GT-3516 QC-3188 GT-3272 GT-3279 GT-3263 GH-1255 GG-2383 GG-2382 GG-2381 GG-2385 GG-2377 XC-0326 QM-3779 QM-3777 YS-2807 GT-3696 GT-3201 GT-3692 GT-3285 $149.00 $14.95 $24.95 $9.95 $299.00 $49.95 $39.95 $79.95 $169.00 $79.95 $24.95 $24.95 $24.95 $24.95 $24.95 $8.95 $59.95 $99.00 $49.95 $59.95 $89.95 $59.95 $79.95 $134.00 $12.95 $9.95 $1.95 $206.00 $34.95 $34.95 $64.95 $109.00 $14.95 $21.95 $21.95 $21.95 $21.95 $21.95 $1.95 $29.95 $52.00 $14.95 $44.95 $79.95 $44.95 $24.95 $15.00 $2.00 $15.00 $8.00 $93.00 $15.00 $5.00 $15.00 $60.00 $65.00 $3.00 $3.00 $3.00 $3.00 $3.00 $7.00 $30.00 $47.00 $35.00 $15.00 $10.00 $15.00 $55.00 Automotive & Outdoors Products Bitumen Based Sound Deadener Bluetooth Hands Free with MP3 Transmitter Charger Car Solar Battery Booster Charger In Car Mobile Phone Fixed Attenuators Globe Bayonet Car 24V 21W In-Dash Multimedia Player with 3" TFT Screen Reversing Sensor with Dashboard Display Speaker Car Vifa 6 x 9" 4 Way 150WRMS Speaker Car Vifa 6.5" Splits 80WRMS Speaker Grille Clamp Kit - Pk.4 Speaker Grille Clamp Kit / 'T' nuts Speaker Mini LCD Screen Speaker Tweeter Piezo Horn - 400W Stereo Bluetooth Adaptor General Consumer Products 2.4GHz 3-Channel RC Car Remote Battery Operated Water Pump BBQ Tool Set Pink Calculator Solar Pink Chess Board with Robot Arm Digital Photo & Video Camera for Kids Helicopter 3Ch Mini IR Helicopter 4Ch Mini with Remote Recharge Helicopter Apache 4Ch RC Houseplant Watering System Deluxe Human Brain Anatomy Puzzle Human Ear Anatomy Puzzle Human Eye Anatomy Puzzle Human Skeleton Anatomy Puzzle Human Skin Model Pedometer with LED Torch Photo Frame Digital 3.5" Photo Frame Digital 7" Portable Stove RC Car - Audi R8 27MHz RC Car - Ferrari 2008 F1 1:10 Scale RC Car - Lamborghini Reventón 27MHz RC Wall Climbing Battle Cars Power Products 2.5V 1W Torch Globe Bi-Pin Type AAA Battery Bank with Alligator Clips and Switch Cliplights - Low Voltage Outdoor Lighting System Globe Halogen 12V 50W 38D Lens Red Globe Halogen MR16 12V 20W Globe Halogen MR16 24V 50W Head Torch 1W Multicolour 4 LED Heavy Duty 70 Amp Battery Power Selector Light - Fluoro for Cabin Lamp ST3006 Light - Fluoro Tube 12VDC Cabin Lamp Light - LED Recessed Blue Light Fluoro 26W Compact Red PAR-56 Black Can Light PEM Fuel Cell Module - 300mW Reflector Caps RF Remote Controlled Receiver 240V Single 240V GPO w/- Extra Switch Solar Lighting System 10W Solar Lighting System 45W Solar Lighting System 5W Spotlight 10 Million Candle Power Spotlight Solar Powered LED Switchmode Power Supply 6VDC 2.5mm Plug Torch Dynamo Pocket Sized Torch LED Keyring with Solar Charging Torch Mini LED - Red Wireless LED Wall Light Security & Surveillance Products 4-Channel to USB Video Adaptor Alarm Kit 4Zone Wireless Economy Alarm Relay Module AV-GAD 8 Zone Alarm Panel with Keypad AV-GAD Alarm Package - 5 Zone AV-GAD Eye Spy 11 Passive Infrared Detector AV-GAD Pro LCD Keypad (AV-707E) AV-GAD Professional Alarm Package - 8 Zone Camera CCD Bullet B&W with Sony Sensor Camera CCD Dome Style B&W 380TVL Camera CCD Dome Style Colour 550TVL Camera CCD Dome Style Low Cost - Sharp Sensor Camera CCD Dome Style Vari-Focal 480TVL Camera CCD Downlight Style Colour Camera CCD Mini B&W in Metal Case with Audio Camera CCD Mini Reversing Colour Camera CCD Pro Style B&W 380TVL Camera CCD Pro Style Colour 350TVL Camera CCD Pro Style Day/Night Colour 380TVL Camera CCD Pro Style Hi-Res Colour 520TVL Camera CMOS Mini 5.8GHz Wireless Colour Camera Dome Dummy with Bracket Camera Dome Style Dummy 3-Axis Camera Pro Style Zoom Colour 480TVL Mini Digital Spy Recorder 2MP Mini Portable Security Recorder Motorcycle Alarm RFID Keypad Access Controller Siren/Strobe Weatherproof Bellbox 12V Siren/Strobe Wireless with Solar Charger Surveillance System with Monitor B&W Off Original RRP. Limited stock, no rainchecks, may not be available at all stores - call your local store to check stock details. Valid from 24th May to 23rd June 2011. Townsville Penrith Ph (02) 4721 8337 YOUR LOCAL JAYCAR STORE Underwood Port Macquarie Ph (02) 6581 4476 Australia Freecall Orders: Ph 1800 022 888 Woolloongabba Rydalmere Ph (02) 8832 3120 AUSTRALIAN CAPITAL TERRITORY SOUTH AUSTRALIA Sydney City Ph (02) 9267 1614 Belconnen Ph (02) 6253 5700 Adelaide Taren Point Ph (02) 9531 7033 Fyshwick Ph (02) 6239 1801 Clovelly Park Tweed Heads Ph (07) 5524 6566 NEW SOUTH WALES Gepps Cross Wagga Wagga Ph (02) 6931 9333 Albury Ph (02) 6021 6788 Reynella Wollongong Ph (02) 4226 7089 Alexandria Ph (02) 9699 4699 TASMANIA NORTHERN TERRITORY Bankstown Ph (02) 9709 2822 Hobart Darwin Ph (08) 8948 4043 Blacktown Ph (02) 9678 9669 Launceston QUEENSLAND Bondi Junction Ph (02) 9369 3899 VICTORIA Aspley Ph (07) 3863 0099 Brookvale Ph (02) 9905 4130 Cheltenham Caboolture Ph (07) 5432 3152 Campbelltown Ph (02) 4620 7155 Coburg Cairns Ph (07) 4041 6747 Coffs Harbour Ph (02) 6651 5238 Frankston Capalaba Ph (07) 3245 2014 Croydon Ph (02) 9799 0402 Geelong Ipswich Ph (07) 3282 5800 Erina Ph (02) 4365 3433 Hallam Labrador Ph (07) 5537 4295 Gore Hill Ph (02) 9439 4799 Melbourne Mackay Ph (07) 4953 0611 Hornsby Ph (02) 9476 6221 Ringwood Maroochydore Ph (07) 5479 3511 Liverpool Ph (02) 9821 3100 Shepparton Mermaid Beach Ph (07) 5526 6722 Maitland Ph (02) 4934 4911 Springvale Sunshine Nth Rockhampton Ph (07) 4926 4155 Newcastle Ph (02) 4965 3799 Arrival dates of new products in this flyer were confirmed at the time Head Office of print. Occasionally these dates change unexpectedly. Please ring your local store 320 Victoria Road, Rydalmere NSW 2116 to check stock details. Prices valid from 24th May to 23rd June 2011. All savings are based on original RRP Ph (07) 4772 5022 Ph (07) 3841 4888 Ph (07) 3393 0777 Ph (08) 8231 7355 Ph (08) 8276 6901 Ph (08) 8262 3200 Ph (08) 8387 3847 Ph (03) 6272 9955 Ph (03) 6334 2777 Ph (03) 9585 5011 Ph (03) 9384 1811 Ph (03) 9781 4100 Ph (03) 5221 5800 Ph (03) 9796 4577 Ph (03) 9663 2030 Ph (03) 9870 9053 Ph (03) 5822 4037 Ph (03) 9547 1022 Ph (03) 9310 8066 Ph: (02) 8832 3100 Fax: (02) 8832 3169 Thomastown Werribee WESTERN AUSTRALIA Maddington Midland Northbridge Rockingham NEW ZEALAND Christchurch Dunedin Glenfield Hamilton Hastings Manukau Mt Wellington Newmarket New Lynn Palmerston Nth Wellington NZ Freecall Orders Online Orders Website: www.jaycar.com.au Email: techstore<at>jaycar.com.au Ph (03) 9465 3333 Ph (03) 9741 8951 Ph (08) 9493 4300 Ph (08) 9250 8200 Ph (08) 9328 8252 Ph (08) 9592 8000 Ph (03) 379 1662 Ph (03) 471 7934 Ph (09) 444 4628 Ph (07) 846 0177 Ph (06) 876 0239 Ph (09) 263 6241 Ph (09) 258 5207 Ph (09) 377 6421 Ph (09) 828 8096 Ph (06) 353 8246 Ph (04) 801 9005 Ph 0800 452 922 SERVICEMAN'S LOG There’s just no pleasing some people While we prefer satisfied customers, every now and then we strike someone who, try as we might, we just can’t seem to please. I don’t let it get to me but for those new to service work or inexperienced at dealing with customers, an unreasonable client can cause sleepless nights. I’d like to say that out of thousands of clients I’ve had over the years, I’ve never had such a customer – but I’d be lying. To be honest, I don’t think one can be in business – or at least a business where you have to deal closely with customers – and not strike at least one or two disgruntled clients. This story is about one of them and if you are a service person, you may recognise a similar situation in your own experience. As is usual, my relationship with this one started out happy and stressfree. She was the wife of a friend’s friend and while I had met her before, we weren’t exactly close. She wanted a new computer and since I had been running my business for a while, she’d heard that’s what I did and asked if I could build a system for her? After sorting out the specifications and price, she gave me the go-ahead siliconchip.com.au and I set about sourcing the parts and doing the build. At 7am the next morning, I got a call asking if the machine was ready. My negative reply seemed to annoy her (at least, that’s what the tone of her voice indicated) and she immediately demanded to know when it would be ready. My response was that I was still waiting on a couple of parts and in any case, I like to burn new systems in for a day or so, to make sure they won’t fall over. Such things can happen and it is better for a new machine to fail on my workbench than after it has been delivered to the customer. I had explained this to her when the machine was ordered. However, some clients hear only what they want to hear and she denied that I had mentioned it. In any event, this first call should have set off warning bells but I was still fairly new to running a business and ignorance can be bliss. A few days later, I delivered the system and everyone was all smiles again. It ripped along nicely and the software she had purchased for it installed and ran well. And so, with the cheque duly banked, I created a scheduler task to call her in two weeks, to see how things were going and to offer any other help. Alas, I heard from her in two days; the machine wouldn’t turn on. I went through my usual phone procedure to ensure things were plugged in and powered up and they all were. It was a mystery until I went around there and discovered she was trying to push a plastic moulding which was not the power button. Instead, the real power switch was located below this, under another admittedly similar-looking but moveable piece of plastic with “Power” clearly printed on it. When I explained this, she looked horrified for a brief moment before launching into a spiel about how she was pushing that one but it wasn’t working. I made my excuses and quickly left, somewhat annoyed but pleased there was nothing wrong with the machine. A few days later I received yet another call, this time at 6.30am on a Saturday morning. She was unrepentant when I told her that calling June 2011  57 Serr v ice Se ceman’s man’s Log – continued at 6.30am was unreasonable; getting her computer going was far more important as far as she was concerned. This time, she claimed that the 17-inch CRT monitor I’d sold her was failing and that the hardware I had supplied was rubbish. She also said that she should have known I couldn’t deliver a better quality machine than company “X” and that she would be seeking a refund and that her husband would be coming around to “sort it out”. To be honest, I had tuned out of the tirade by then. Instead, I told her that if she had a problem with the hardware, all she needed to do was bring it back and it would be dealt with under the warranty. Well, her husband did come around and he brought the monitor with him. I plugged it in and it worked perfectly, though he said that at their place the image was all distorted and the colours were way off. I couldn’t explain that one; my thoughts went to either an intermittent cable connection or even the graphics card failing, although this seemed unlikely. In the end, we decided to go back to their house and test it in-situ. With the monitor back in position, I connected it to the computer while the wife rearranged various ornaments around it, with one even going on top. And sure enough, when we turned it on, the image was pulled upwards and it displayed some very odd colours. It didn’t take a genius to figure out it was the magnetic sculpture she had placed on top of the monitor. This magnetic doo-dad consisted of a heavy magnetic base and hundreds of tiny star-shaped metal pieces that could be infinitely rearranged and held in place by the strong magnetic field. Of course, this played havoc with the CRT 58  Silicon Chip and once I removed it and degaussed the monitor, everything was back to normal. Despite the evidence, she then tried claiming that it was playing up before she put anything near it but I told her I seriously doubted that. I also said that we would happily replace the monitor if it failed but I never heard from her ever again. I cannot decide whether that was a good thing or a bad thing – good because I didn’t find her easy to deal with; bad because I may have lost a customer through no fault of my own. Laptop fan maintenance Laptops can really get my hackles up. I say this because while they are without doubt incredibly useful (and often indispensable), my servicing experiences have dampened my enthusiasm for them. A classic scene in our workshop is the air turning blue as one of us struggles to find that last screw or clip holding the whole thing together. No matter how many laptops I pull apart, it seems like each model is unique when it comes to screw positions, clips and cable connections. Some machines just about fall apart, while others fight every step of the way. I swear they are designed by the same people who made British cars in the 1950s and 1960s, with impossibleto-access screws buried under panels behind covers beneath stickers. When servicing a laptop, one of our most common maintenance tasks is to clean out the ventilation holes, the CPU heatsink and any fans. This is because cooling systems in many laptops are barely adequate even when new. Throw in a layer of nicotine-flavoured grime on the ducting and things soon start heating up, especially if the fan has slowed down due to wear and tear and lack of lubrication. Now you’d think that the manufacturers would keep this in mind and put the whole caboodle under one easy-to-access panel. But no; out of the hundreds of laptops I’ve serviced over the years, I have struck only a handful where this is the case. Not only are the fans typically at the bottom of the disassembly chain, even when you get there you aren’t really there yet. Often, any air gaps will have been sealed with “stick-likeyou-know-what to a blanket” singleapplication tape. This then has to be ruined in order to be able to remove the parts underneath. And because we can’t buy this exact-same tape, everything from gaffer tape to duct tape is pressed into use as a substitute. Then there are the fans themselves. Most are considered non-repairable and are enclosed in sealed metal cases which are crimped or folded together. So in order to expose the bearing surfaces for lubrication, you need to either drill a small hole through the case and risk damaging the fan or pry the thing apart in the hope that you can get it all back together again. And if you do get it back together again, it had better be just as compact and dent-free as when you started, otherwise the fan will rub against it and nothing will fit at all. Once you get to the cooling components, cleaning them is easy. My major gripe is the fact that you have to disassemble and virtually half-wreck everything in order to get to them and complete what should be a very simple job. When you present the invoice to the client, “clean and lubricate fans” doesn’t really reflect the actual labour involved. Instead, it’s just one of many “simple” jobs we have to regularly undercharge in order to maintain customer goodwill. Insurance reports It’s not unusual for us to be asked to write reports for clients making claims against insurance policies. In my line of work, this is usually when a laptop has been accidentally damaged because either something has been spilt on it or it has been dropped. Desktop machines can also suffer accidental damage, eg, when a nasty power surge takes out the power supply and everything else in the case. More recently, because we live in Christchurch, it has been earthquake damage reports and lots of them. In the majority of cases, this involves generating a report stating what we believe happened to the equipment, the damage done and the approximate cost of repair. We’ve done so many that we now have a large collection of “templates” on file for the most common problems and misadventures. This means that, when a new insursiliconchip.com.au ance job comes in, all we have to do is change the relevant client details and add or remove any model or claimspecific information before hitting “Print” or “Send”. There is no point wasting time and energy generating new reports from scratch when there is one almost ready to go except for a few sundry details. In 99% of cases, this allows us to trot out a comprehensive report that will satisfy the most jaded assessor/ adjuster. However, human nature being what it is, every now and then we get a customer who wants to bend the truth and aim a little higher than they know they should. However, while it’s not unusual for people to overestimate what their hardware is worth, it’s quite another thing to deliberately try to diddle some “free” money from insurance companies. I don’t doubt that there are some service people out there who have no qualms about making inflated claims on behalf of clients, their rationale being that this is a “victimless crime” and therefore somehow acceptable. The problem is, legitimate customers ultimately end up covering the losses incurred by frauds and scams by way of higher premiums, so it’s hardly a victimless crime. We always try to be scrupulously fair in our reports. We listen carefully to what the client tells us and as long as the damage and evidence bears that out, there is no problem in making claim. Determining the replacement cost can be tricky though. After all, computer equipment that may fetch just $150.00 in today’s market may have cost the client a thousand dollars or more just a few years ago. As a result, we compare their hardware with what is available now and set our estimate at what similar replacement equipment would cost. That means that the client gets a “like for like” replacement, which I think is the fairest outcome for everyone concerned. For example, if the damaged machine sported an expensive motherboard, dual high-end video cards and other expensive parts, then our estimate would be based on the cost of a similar machine using current high-end technology. Similarly, if it used mid-range hardware, then our estimate would be for a machine with mid-range hardware. We do have to take into account the age of the damaged equipment in making our estimates though. Of course, all this only holds good if the insurance people listen to us and take our advice. All too often we get them coming back and valuing the machine at a lower figure, usually because they have arrived at their estimate using cheaper or lower-quality replacement hardware. That puts us in a tough position because the clients often come back to us, concerned with the disparity. In the end, most are willing to take the cash on offer and add whatever is required to make up the difference to get the machine they want, rather than opt for a lower-end machine. It’s also a tough call if it’s a major client pushing for a false appraisal, because turning them down will likely result in the loss of their business. However, tempting as it might be to keep onside with them, a prosecution for insurance fraud doesn’t look good on the CV and we’d risk losing far more than one client, so our answer is always an uncompromising “no”. It has taken me many years of hard graft to build my company and its current reputation and I am not about to jeopardise that for the sake of one client, no matter how important they may appear to be to our business. Besides, I have to be able to sleep at night. The koala did it In this age of natural disasters and shrinking computer repairs, any job we can charge for is fair game. We are prepared to take on just about anything and so a wide variety of items find their way onto the workbench. One such job appeared the other day and I had to double-check just to be sure the client really wanted to spend money getting this item repaired. That’s because it was a bog-standard halogen desk lamp, the likes of which can be purchased at many stores for as little as $10. This one featured a small, rounded head-unit housing the reflector, halogen bulb and cover glass. This assembly sat atop what appeared to be two telescopic transistor radio aerials Australia’s Best Priced DSOs Shop On-Line at emona.com.au RIGOL DS-1052E 50MHz RIGOL DS-1102E 100MHz RIGOL DS-1202CA 200MHz 50MHz Bandwidth, 2 Ch 1GS/s Real Time Sampling USB Device, USB Host & PictBridge 100MHz Bandwidth, 2 Ch 1GS/s Real Time Sampling USB Device, USB Host & PictBridge 200MHz Bandwidth, 2 Ch 2GS/s Real Time Sampling USB Device & USB Host Sydney Brisbane Perth ONLY $439 inc GST Melbourne Tel 02 9519 3933 Tel 03 9889 0427 Fax 02 9550 1378 Fax 03 9889 0715 email testinst<at>emona.com.au siliconchip.com.au ONLY $769 inc GST Tel 07 3275 2183 Fax 07 3275 2196 Adelaide Tel 08 8363 5733 Fax 08 8363 5799 ONLY $1,422 inc GST Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au EMONA June 2011  59 Serr v ice Se ceman’s man’s Log – continued pressed into service to form the “stalk” of the lamp. These two “aerials” ran parallel to each other, about 40mm apart, all the way down to a heavy base unit some 250-300mm below. This dome-shaped base housed the on/off switch and the components required to power the lamp. The only real difference I could see between this lamp and other similar lamps was that this unit had a company logo screen-printed on it. Apparently, it had sentimental value and the client wanted us to “have a look” to see if we could do anything with it. The reported symptoms were low-to-no light output and the base was getting hot. Looking underneath, I could see the removable bottom was indeed slightly heat-warped, which is never a good sign. The screws were hidden under the rubber feet which crumbled into rubber dust as I carefully tried to prise them clear. Once the screws had been undone, the base dropped away to reveal a hefty-looking transformer and, well, nothing else. Not having disassembled one of these before, I was mildly surprised to find just a tranny hiding in there. It made sense though; the bulb only needed 12V AC and the transformer stepped the juice down from 230/240V AC to the required voltage. This was then fed to the bulb assembly via the two telescopic “aerials”. I was quite surprised at this. Initially, I had assumed that the wires ran up the hollow insides of the “aerials”. However, in this lamp, the “aerials” are themselves the conductors, ie, they are live, albeit with just 12V AC across them. A quick check with the multimeter revealed the secondary of the transformer to be open-circuit. Fortunately, we had one in stock that was about the same size, physically and electrically. Using Ohm’s Law, I calculated the 20W bulb’s approximate current draw to be 1.66A and although I had no idea of the replacement transformer’s exact specifications, it certainly looked capable of doing the job. Anyway, I fitted the transformer and the happy client took her now-working lamp home. However, a few days later it was back with the same problem. This time, however, the heat damage was more pronounced. Puzzled by this, I quizzed the client as to where the lamp sat and asked if anything nearby touched it or obscured the rather limited air-cooling vents. In the end, with no obvious answers, I replaced the transformer and back it went, with me thinking that that would be the end of it. But no; she back was on the phone the very next day claiming the lamp was very dim and “smelled hot”. I asked her to turn it off, not touch Issues Getting Dog-Eared? Keep your copies safe with these handy binders Available Aust. only. Price: $A14.95 plus $10 p&p per order (includes GST). Just fill in and mail the handy order form in this issue or call (02) 9939 3295 and quote your credit card number. Buy five and get them postage free! 60  Silicon Chip REAL VALUE AT $14.95 PLUS P&P anything and wait for me to get there. As soon as I saw it, things began to make sense. Once she’d put the lamp back on her desk, she’d set about replacing all the trinkets and “objets d’art” that usually lived around it. She had also clipped a small souvenir koala bear (the type which “grabs” anything placed between its springloaded forepaws) half-way up the telescopic “aerials”. However, due to the way she’d attached it, the sprung metal clip inside the souvenir touched and therefore bridged both “aerials”, effectively shorting out the secondary of the transformer. As soon as I moved the clip away from one of the aerials, the lamp burst back into life. And so the problem was easily solved although I have to say that the design of this unit leaves something to be desired. These days, margins are such that service work is usually only profitable if a job is done once. Any warranty claims or any further unpaid work will eat up any profit. In this case, I did the job twice and stood the cost of the first transformer as well, not to mention the time I spent going around to the client’s house. To offset the possibility of having to revisit jobs, we try to ask the right questions to nail down what the problem might be. It also helps if clients answer these questions as accurately as possible. In this case, I specifically asked this client if anything was touching the lamp when it was in use and you’d think that physically clipping something onto the lamp would fall into the category. I’m also surprised the client didn’t “click” that the lamp stopped working when she clipped the koala to it. Oh well, just another day at the office! My next story is from A. F. of Chinderah, NSW and concerns an air-conditioner that was repeatedly failing. Here’s how he tells it . . . Recalcitrant air-conditioner Enid is an elderly pensioner who had found the going tough since her husband died. And with her airconditioner now on the blink, it had just got tougher. When the unit first stopped working, a repairman charged her $100 to get it going again, which Enid gladly paid. However, a few months later, it stopped working again and Enid paid another $100. Now it had stopped siliconchip.com.au siliconchip.com.au ACOUSTICS SB working for the third time and Enid had decided that paying her rent and keeping her car running were more important than keeping cool. The result was that she now suffered the hot and humid weather of the Northern Rivers district in NSW while the unit stood idle. When I heard of her plight, I immediately offered to look at the unit, more as a token of sympathy than in the hope of affecting a repair. In my younger days, I had re-gassed two refrigerators using borrowed equipment but I now no longer had the friends to help me out. I phoned a local air-conditioning company and found out that the standard call-out charge was $100. Re-gassing cost around $350, while a new system would cost about $3500. So it seemed that Enid’s unit had not required re-gassing and the problem was something more minor. Enid lived in a nice retirement village. When I got there, my first step was to remove the batteries from the A/C’s remote control unit and check them on my battery tester. They tested OK and there were no signs of corrosion in the battery compartment, so I reinstalled them. Next, I focussed my digital camera on the infrared LED end of the remote and pressed the remote’s on-off button. This resulted in faint flashes of light on the camera’s LCD, so it looked like the remote was working OK. However, the A/C unit on the living room wall would not respond to any button presses, so it was time to investigate both the outdoor section of the A/C and the meter box. Enid showed me where the meter box was and as soon as I opened the door, I could see a problem. The circuit breaker marked “A/C” had tripped and I was glad that Enid was there to see the fault for herself. There was not much more I could do other than reset it, so I turned off the main switch, reset the circuit breaker and then turned the main switch back on. In fact, this reminded me of a customer who found that a circuit breaker in his meter box had tripped. He had attempted to switch it back on without first switching off the mains. When he did so, the circuit breaker exploded as it tried to switch itself “Off” while being forced “On”. In turned out that the circuit breaker had tripped because a leaking roof had caused a dead short condition. Fortunately, there were no dramas when Enid’s mains switch was flicked back to its “On” position, so it was time to see if the A/C unit would now respond to the remote. Sure enough, the A/C unit responded immediately and a delightful rush of cool air descended from the unit on the wall. Enid was thrilled. So what had happened to trip the circuit breaker? A retired friend explained that these retirement village units had been fitted with 15A circuit breakers when they were built. Since then, the supply voltage had been reduced from 240V to 230V AC and so the A/C motors would draw more starting current. Add in the fact that the motor bearings probably now had higher friction due to ageing and it’s easy to see why the circuit breaker might occasionally trip. Fitting a new circuit breaker with a “D” curve would probably solve the problem permanently but I was content to leave my phone number with Enid. If I can save a battler $100 just by flipping two switches, then I am SC happy to do so. CEILING & IN-WALL TWO-WAY SPEAKERS SUPERIOR SOUND QUALITY AND PERFORMANCE dynamica June 2011  61 1 F 100nF 10k Vdd 2 RA0 RA7 RB4 RA1 RB5 RB3 RA3 0nF AN5 Q5 BC547 AN6 AN2 Q1 BC327 B 16 C A C B E 7 8 220nF C Q2 BC327 K C X Y C B E E 10k 15 9 TIMER X PULSE VR3 10k 12 + VR2 10k COM NO Y TP3 13 SINGLE COIL LATCHING RELAY +11.4V 1 1k RB1 LK4 POWER UP + + 0–5H 2 10nF 0–50s BOTH OPEN = 0–5m X Y By JOHN CLARKE VersaTimer/Switch RB2 RA4 Vss 5 3 Q6 BC547 B 11 6 1k TO RELAY COIL(S) A RB0 A Q4 BC337 TP2 470k  LED2  Q3 BC337 2x470 10 LED1 K C E IC1 PIC16F88-I/P 1 1k MCLR RA6 1k 10k 4 A 18 RESET S2 14 17 +5V 1 1k LK3 OPERATION DOUBLE COIL LATCHING RELAY MOMENTARY 2 10nF NC COM NO NC COM NO (NOTE: Q1, Q2, Q5 AND Q6 NOT REQUIRED FOR DOUBLE COIL RELAY) TOGGLE BOTH OPEN = FOLLOW LEDS Use it as a micropower switch, programmable timer and/or 12V battery protector K A D4: 1N4148 A K MCP1703T BC327, BC337, BC547 IN Do you have a D1-D3 switching application ZD1 that calls for a relay but B GND A current K needs very low drain? You won’t get satisfaction if you OUT E A K use a conventional relay – it pulls too much current. You need this circuit board which uses a 12V latching relay. As a bonus, it functions as a programmable timer and battery protector. T HIS PROJECT WAS first conceived to update the DC Relay Switch from our November 2006 issue. That project would operate a high-current relay in response to any DC or pulse signal and it also employed an optocoupler to provide full isolation between the control signal and the circuit being switched. Now while that project was OK there has been an increasing need for a relay switching circuit which consumes the 62  Silicon Chip very minimum of power, whether or not the relay is energised. The problem is that all conventional relays draw some current continuously when they are energised and that can be a major drawback in battery-operated circuits. The current through the relay coil depends on the particular relay. For 12V relays, the coil current can be as low as 12mA for a 500mA reed relay, 30mA for a 3A relay and more than 100mA for a 30A relay. This coil cur- C rent must be continuously applied to keep the relay contacts closed. The solution: use a latching relay. This type of relay only draws a brief pulse of current when its relay contacts are changed from the closed or open condition. At all other times, it draws no current at all. So how does a latching relay work? Well, instead of just using a moving armature (to operate the contacts) together with a coil wound on a steel siliconchip.com.au core (an electromagnet), a latching relay has a couple of bar magnets and these hold the relay contacts in one position (eg, closed) or the other (eg, open). The electromagnet effectively toggles the relay contacts from one position to the other just as you do when you operate a light switch in your home. However, in the light switch example, the switch is held in the open or closed position by spring action. By contrast, the latching relay uses magnets to do the same job. But while latching relays are good (ie, they don’t draw current continuously), they are much more difficult to drive than conventional relays. The circuitry required to drive them is more complicated as we shall see. Multiple functions As indicated, this “VersaTimer/ Switch” circuit drives a latching relay. It also provides a useful timer function which can provide latched or momentary operation and can switch power on for a predetermined period or switch it off after a predetermined period. Or it can switch on and off alternately, according to your settings. To top it off, it also provides a battery protection feature, preventing the battery from being too heavily discharged. This is important in circuits which run from lead-acid and particularly sealed lead-acid (SLA or gel) batteries. All these features are provided by a small PIC microcontroller. Now before you fall about laughing or reel back in dismay, stay with us while we give you the reasons for using a micro rather than a bunch of transistors and maybe a logic IC or two. Well that says it all really because a bunch of transistors and logic ICs would end up being a lot more complicated and provide less functions than our circuit. Nor would a discrete version have the low power consumption of this circuit. Latching relays use either one or two coils to drive the relay into each state. For a single coil type, you need a pulse of current to switch from one state to the other and then a pulse in the opposite direction to change state again. A double-coil latching relay requires a pulse of current in one coil to provide the set (on) position for the contacts and then another pulse of the same polarity to be applied to the second coil to produce the (off) reset condition for the contacts. There is more discussion on latching and non-latching relays in a siliconchip.com.au The circuit is housed in a standard IP65 case (115 x 90 x 55mm). Two versions can be built – one to switch the mains (as shown here) and one to switch voltages up to 30V DC <at> 2A. separate panel at the end of this article. The VersaTimer/Switch has been designed to suit both types of latching relay, ie, single or double-coil. The double-coil relay has DPDT 2A contacts and the single coil relay has SPST 60A (or 80A) contacts. The drive circuitry is also suited to other latching relays that may not necessarily fit onto the PCB for the VersaTimer/Switch. Because latching relays have differing pulse length requirements when switching relay states, the pulse duration can be adjusted to suit the relay specifications. Isolated triggering For most uses, a trigger signal is required for the VersaTimer/Switch. This trigger signal can be 0V for one relay position and 5V for the alternative relay position. For example, the trigger can be obtained from a circuit that drives a LED or from any other suitable voltage signal. In addition, the input trigger signal Main Features • • • • • • • • • Very low current drain Electrically isolated control input Low battery protection 60A (or 80A) 250VAC SPST relay or 2A 30VDC DPDT relay Relay options include input follow, alternate or momentary Adjustable input switching sense High, low or high and low switching with momentary action Adjustable relay drive pulse duration Timer periods from seconds to 5 hours Main Uses (1) Standalone timer (2) Low battery power switch or battery isolator (3) Low power relay control from DC or pulse signal June 2011  63 Specifications Specifica tions Supply voltage ....................................................................................................................12V nominal Relay type ...........................................................................................................................12V latching Relay drive pulse ....................................................................................................1-500ms adjustable Pulse current at 12V ........................15mA (<at>25ms) for SY-4060, 85mA (<at>60ms) for JMX-94F-A-Z Low battery threshold ............................................................................................. <11.5V (adjustable) Low battery upper threshold (switch back on) .............................................................................>12V Battery voltage monitoring ............................................................................................ 6ms every 10s Timer function ...........................0-50s (200ms minimum, ~200ms steps), 0-5m (8.4s minimum and 36 x 8.4s steps) or 0-5h (2.38m minimum and 127 x 2.38m steps) Isolation ..................................................2500VAC between coil and contacts for 60A and 80A relays Trigger input isolation .................................................................. up to 50V maximum recommended Quiescent current ..............................................................17µA maximum, 13.3µA measured at 12V; add 10.6µA when RB2 is low and add 0.6µA during any timing period Low battery quiescent current .......................................................................................................17µA Maximum trigger voltage ......................................................... 35V with 10kΩ 0.25W resistor for R1 Minimum input voltage ......................3.25V for R1 = 10kΩ (alternative R1 for lower voltages: 1.5kΩ for 1.5V, 3kΩ for 2V, 6.2kΩ for 3V) Minimum input trigger current at In+ and In- .............................................................................225µA Maximum input trigger current ................................................................................................... 60mA is optically isolated and can operate from a floating potential. Triggering can also be from a momentary pushbutton switch or toggle switch, depending on the application. When used as a replacement for a non-latching relay, the VersaTimer/ Switch responds to follow the input signal. So when the input signal is off, the relay is set to one state (for example, with its contacts open) and when the trigger signal is on (ie, trigger voltage is present) the relay is switched to its alternative state with its contacts closed. You can select which relay state occurs with which input signal. Low voltage monitoring This function is independent of the input triggering function. In addition, the typical current drawn by the VersaTimer/Switch is very low at around 13.3µA. Timer function The VersaTimer/Switch can be set to switch on or off with a trigger signal for a period from seconds through to five hours. It can be triggered from a high to low signal (eg, 5V to 0V), a low to high signal (eg, 0V to 5V) or from both voltage edges. Circuit description Refer now to Fig.1 for the complete circuit for the VersaTimer/Switch. It’s 64  Silicon Chip based on a PIC16F88-I/P microcontroller (IC1) which monitors the input trigger signal and drives the latching relay via transistors Q1-Q6. It also monitors the inputs that define all the circuit functions, including low battery protection. The trigger input is via IC2, a 4N28 optocoupler. This comprises an infrared LED and phototransistor in a 6-pin DIP package. When the infrared LED is not driven (off), the phototransistor is off. When the LED is on, the phototransistor is switched on. It can be driven by either AC or DC signals, since the internal LED is shunted with diode D4. The optocoupler provides isolation for the trigger input. This isolation allows the input LED to be driven from a signal that is not referenced to the supply ground of the VersaTimer/ Switch. We recommend a maximum of 50V between the LED drive signal and the supply ground for the VersaTimer/Switch. The input trigger current is typically 400µA when 5V is connected between the input “+” and “–“ terminals. This current is set by the 10kΩ limiting resistor (R1) and the 1V drop across the infrared LED. Minimum input trigger current is 225µA and so the input voltage can be as low as 3.25V, with a 10kΩ resistor. For lower input voltages, R1 can be changed to 1.5kΩ for 1.5V, 3kΩ for 2V and 6.2kΩ for 3V. The phototransistor inside IC2 is tied to the high (+5V) RB1 output of IC1 via a 470kΩ resistor. A 220nF capacitor keeps RB2 low when a lowvoltage 50Hz AC signal is applied to the trigger input. The 100Ω resistor is included at the emitter of the optocoupler transistor to limit the current when discharging the 220nF capacitor. S1 is included as a test switch to check the operation of the relay switching. Power saving strategies There are a number of aspects of this design which are included to save power. If the battery voltage is low, the 470kΩ pull-up resistor at RB2 is tied low via the RB1 output. This reduces the current flow should the phototransistor within IC2 be conducting due to infrared LED current. This feature reduces the supply current by 10.6µA when IC2 is conducting. While IC2 provides isolation of the input trigger signal, optocoupler IC3 is included simply to save power. IC3 is turned on when the RA0 output of IC1 goes high, to drive the internal infrared LED. This turns on IC3’s phototransistor to connect the voltage divider comprising the 22kΩ resistor and VR1 across the input supply, so that it can be monitored by the AN2 input. If this divider were permanently connected, then the current would be 363µA. By turning on the optocoupler for just 6ms every 10 seconds, we use 6.4mA to briefly drive the optocoupler LED but the average current to monitor the battery voltage drops to just 4µA. Power is also saved by running IC1 at 31.25kHz using an internal oscillator and divider. At this frequency, the microcontroller itself draws a mere 35µA. That’s pretty good but IC1 is also placed in sleep mode for most of the time, so that its current drain reduces to just 11µA (maximum). It’s awakened every 40ms for a short duration In addition, REG1 is a low quiescent power regulator that draws a mere 2µA. Further power savings are achieved by ensuring that IC1 applies voltage to trimpots VR2 and VR3 only at power up and when switch S2 (Reset) is pressed. These trimpots are used for setting the timer functions and are monitored by the AN6 and AN5 inputs of IC1. IC1 only needs to check these settings at power up as they do not change during operation. When the reset switch is pressed, siliconchip.com.au siliconchip.com.au June 2011  65 R1 10k  D4 A K 470 2 1 K 10 A K 2 1  IC2 4N28 4 5 TPG TP1 100 LOW (BOTH OPEN = HIGH & LOW) LK2 EDGE HIGH TRIGGERING LK1 COIL POLARITY ZD1 16V 1W S1 TEST 10nF 2 1 2 1 IN +5V 1 F VERSATIMER/SWITCH 4 5 IC3 4N28 22k A D1 1N4004 OUT 1k 8 7 1 2 18 17 1 F 100nF 470k A 220nF 10nF GND 14 4 RB2 RB1 AN2 Vss 5 RA4 RB0 AN6 AN5 RB3 RA6 RB5 RB4 RA7 MCLR IC1 PIC16F88-I/P RA3 RA1 RA0 Vdd 10k 3 6 13 12 9 15 11 10 16 A TP2 TP3 K 10k A VR3 10k 2 1 2 1 B MOMENTARY OPERATION E C C E A A ZD1 A Q3 BC337 K K D4: 1N4148 TOGGLE BOTH OPEN = FOLLOW LK3 0–50s BOTH OPEN = 0–5m 0–5H B Q1 BC327 B LK4 POWER UP VR2 10k E C 1k PULSE Q5 BC547 2x470 +5V TIMER 10nF 10nF D1-D3 1k 1k S2 RESET 10k D2 A K  K D3 Y Y X +11.4V + E C C E B B Q2 BC327 1k GND OUT IN MCP1703T K E B C BC327, BC337, BC547 A LEDS (NOTE: Q1, Q2, Q5 AND Q6 NOT REQUIRED FOR DOUBLE COIL RELAY) DOUBLE COIL LATCHING RELAY + + NC COM NO NC COM NO COM NO B Q6 BC547 100 F 16V 10k E C 10k SINGLE COIL LATCHING RELAY Y X A Q4 BC337 K  LED2 A 2.2k TO RELAY COIL(S) X LED1 K +11.4V Fig.1: a PIC16F88-I/P microcontroller (IC1) is used to control the latching relay via switching transistors Q1-Q6 (or Q3 & Q4 only if a double-coil relay is used). IC1 also monitors the trigger input via optocoupler IC2 (ie, at its RB2 port), while other ports monitor the trimpot and link settings to set the edge triggering and relay modes, the timer and the power-up defaults. Optocoupler IC3 is included as a power saving measure – it turns on only when IC1’s RA0 port goes high and applies voltage to VR1 so that the PIC microcontroller can monitor the input supply rail. 2011 VR1 20k SC  0V – INPUT + V+ 0V +12V REG1 MCP1703T-5002E/CB 0V 10k 1k S1 S2 TP2 IC2 VR3 VR2 100Ω Q5 470Ω 220nF 4N28 TP GND D3 4004 10k 2.2k LED2 LED1 10k TP3 4148 D4 4004 2 10k 1k IC1 PIC16F88-I/P – LK3 2 1 LK4 2 10nF RELAY 11160191 IC3 4N28 1 + 10nF IN 100 µF 1 100nF LK1 Q2 K 1k 10k TP1 470k V+ 1 LK2 2 1k 10nF 0V D2 10nF 470Ω +12V 10k K VR1 22k CON1 Q1 H CTI WS YALER G NI H CTAL D1 4004 (UNDER PCB) 1 µF CER 1k 16V 10Ω REG1 1 µF CER ZD1 470Ω Q4 Q3 WIRED FOR SINGLE COIL LATCHING RELAY 4148 D4 TP GND S2 TP2 100Ω VR2 VR3 D3 4004 H CTI WS YALER G NI H CTAL NO NC 11160191 CON3 COM NC CON4 – – NC + + NO RELAY NO COM MAXIMUM RELAY CONTACT RATING = 30VDC <at> 2A TP3 220nF 2.2k LED2 LED1 D2 4004 100 µF COM 1k S1 IC1 PIC16F88-I/P LK3 2 1 LK4 2 10nF 2 470Ω 10k 100nF LK1 IC2 0V 1 4N28 – 1 µF CER 1 µF CER IC3 1 + 10nF IN 1 LK2 2 1k V+ K 10k TP1 470k 0V K 10nF 470Ω 4N28 10nF CON1 (UNDER PCB) VR1 22k 1k D1 4004 10Ω 16V +12V REG1 470Ω Q3 Q4 WIRED FOR DOUBLE COIL LATCHING RELAY Fig.3: this version uses the Jaycar SY-4060 double-coil latching relay which has contacts rated at 30VDC <at> 2A. DO NOT use this version to switch the mains or other high voltages. the RB3 pin, which is normally an input, is set as an output and it goes high to 5V for the time required to read the trimpot settings. When high, the circuit current is increased by 1mA. Yet another power saving tactic involves preventing inputs RA3, RA4 & RB0 from floating if their respective link selections LK2, LK3 & LK4 do not have a link inserted. Any input that 66  Silicon Chip Fig.4: regulator REG1 is a surfacemount device and is mounted on the underside of the PCB as shown here. You will need a fine-tipped soldering iron to install it – see text for details. Q6 Fig.2: this is the version to build if you want to switch the mains (230VAC). It uses a 12V 60A or 80A single-coil latching relay with the contacts on the side (see photo). Refer to Fig.5 for the mains wiring details. ZD1 REG1 ON UNDERSIDE OF BOARD floats between 0V and 5V will cause that input to draw power. This is prevented by periodically driving these ports low for 500µs every 40ms. The 10nF capacitors keep the ports low between each drive period. Relay driving options If you are using a single-coil latching relay, it is driven using transistors Q1-Q6. For a double-coil relay, only transistors Q3 & Q4 are used and the other four transistors are omitted. In this case, the “+” sides of the relay coils are connected to the +11.4V supply and either Q3 or Q4 is switched on to drive the set or reset coil. Diodes D2 and D3 quench the backEMF voltage spike when the driven relay coil is switched off. D2 clamps the voltage when Q3 switches off and D3 clamps the voltage when Q4 switches off. We need all six transistors to drive the single-coil latching relay because we need to change the connection polarity to the coil to provide the set and reset pulses. For one polarity, RB4 switches on transistor Q3 and this connects one side (X) of the coil to 0V while the other (Y) side of the coil is connected to +11.4V via transistor Q2 which is switched on by Q6 when RA6 goes high. For the opposite polarity drive, Q4 is switched on by RB5 and Q1 is switched on via Q5 when RA7 goes high. Diode D2 quenches the stored charge within the relay coil when Q3 is switched off and to ensure this diode fully shunts the current, transistor Q2 is kept conducting for sufficient time after Q3 is switched off. Similarly, when Q4 is switched off, transistor Q1 is kept conducting to allow D3 to fully clamp the voltage as the coil field collapses. Link options Link LK1 selects the set or reset polarity for the relay coil drive circuitry. This is necessary for the battery protection function, so that the relay disconnects the load if the voltage siliconchip.com.au DPDT relay version uses less transistors and resistors compared to the SPST relay version. Figs.2 & 3 shows the parts layout on the PCB for the two versions. Start the assembly by installing regulator REG1 on the underside of the board as shown in Fig.4. This surface-mount part can be easily installed by first using a pair of self-closing tweezers to hold it in place while one of its legs is soldered. That done, check that the component is positioned correctly over the mounting pads before soldering the remaining two pins. Once REG1 is in position, flip the board over and install the single wire link. This goes in just below VR1 and you can either use 0.7mm diameter tinned copper wire or a 0Ω resistor. The resistors are next on the list. Table 1 shows the resistor colour codes but you should also check each one using a digital multimeter before soldering it into position. Follow with diodes D1-D4 and zener diode ZD1, taking care to ensure that they are all correctly orientated. Now for the transistors. Install Q1Q6 for the single-coil relay version but note that only Q3 & Q4 are installed if you are using the double-coil relay. Take care to install the correct transistor type in each position and make sure that they are correctly orientated. IC2 and IC3 can now be installed, along with an 18-pin socket for IC1. These parts must also be correctly orientated – see Figs.2 & 3. Leave This assembled PCB is for the version shown in Fig.3. Take care with parts orientation. drops below the threshold voltage set by trimpot VR1. The adjustment procedure is described later in this article. Links LK2-LK4 can be tied to the RA0 output (which can be high) or tied low to 0V. Alternatively, the associated inputs – RA3, RA4 & RB0 – can be left open circuit (ie, without a link). IC1 checks whether or not a link is installed by first setting its RA0 output high. If a link has been installed between the “A” terminal and an input, that will then cause that input to go high. Conversely, if a link has been installed between an input and 0V, that input will go low. An input without a link connection can be driven both high and low. Reading the input levels after driving the RA3, RA4 and RB0 pins high and low as outputs allows IC1 to determine which links are installed. LEDs 1 & 2 indicate the relay switching. LED1 lights whenever transistor Q3 is switched on and LED2 lights whenever Q4 is switched on. The length of time each LED lights is set by the relay pulse length. Construction The VersaTimer/Switch is built on a PCB coded 19106111 and measuring 103 x 78mm. This fits neatly inside an IP65 polycarbonate case measuring 115 x 90 x 55mm, with the PCB secured to the integral stand-offs using M3 x 6mm screws. Begin be checking that the PCB has the necessary corner cut-outs so that it fits into the box. It can be filed to shape if necessary using the PCB outline shape as a guide. That done, check the PCB for any breaks in the tracks or shorts between tracks and pads. Check also that the hole sizes are correct by test fitting the larger parts (ie, the screw terminal blocks and relay). The corner mounting holes should be 3mm in diameter. Note that two different versions can be built, each using a different relay. Both use 12VDC latching relays but these have different contact configurations and ratings. One relay is a double-coil type with 2A DPDT contacts (Jaycar SY-4060), while the other is a single-coil type with 60A or 80A 250VAC SPST contacts. Follow the correct overlay diagram for your particular relay. The assembly is almost exactly the same for each version. However, the Table 2: Capacitor Codes Value 1µF 220nF 100nF 10nF µF Value IEC Code EIA Code 1µF   1u0 105 0.22µF 220n 224 0.1µF 100n 104 0.01µF   10n 103 Table 1: Resistor Colour Codes o o o o o o o o o siliconchip.com.au No.   1   1 2/6   1 3/5   3   1   1 Value 470kΩ 22kΩ 10kΩ 2.2kΩ 1kΩ 470Ω 100Ω 10Ω 4-Band Code (1%) yellow violet yellow brown red red orange brown brown black orange brown red red red brown brown black red brown yellow violet brown brown brown black brown brown brown black black brown 5-Band Code (1%) yellow violet black orange brown red red black red brown brown black black red brown red red black brown brown brown black black brown brown yellow violet black black brown brown black black black brown brown black black gold brown June 2011  67 4148 4148 PCB M3 x 15mm TAPPED NYLON SPACER AGAINST SIDE OF PRESSPAHN COVER (HELD IN PLACE VIA M3 x 6mm NYLON SCREW) RELAY RELAY CONTACT TERMINALS HEATSHRINK SLEEVING COVERING SOLDER JOINTS & TERMINAL ENDS PRESSPAHN COVER OVER MAINS CONNECTIONS (SEE BELOW) CABLE TIE HOLDS END OF CABLE IN PLACE This view shows how the mains wiring is installed. Insulate the relay terminals with heatshrink and be sure to use Nylon screws to secure the Presspahn cover. Heavy cable will be required to cope with high currents. M3 x 6mm NYLON SCREW & NUT BOX USE M3 x 6mm NYLON SCREW FOR MOUNTING THIS CORNER OF PCB CORD GRIP GROMMET header strip. Install them in the positions shown but leave the jumper links off for the time being. Finally, complete the PCB assembly by installing PC stakes at TP1, TP2, TP3 & TP GND, followed by switches S1 & S2. These miniature switches go in at the bottom left of IC1. SHEATHED MAINS RATED CABLE Fig.5: here’s how to wire the version shown in Fig.2 to switch the mains. Make sure that the 2-wire mains cord is adequately rated for the job and that it is anchored to the case using a cordgrip grommet. You must also insulate the relay terminals with heatshrink and make a Presspahn cover (see below) to isolate the mains connections from the low-voltage circuitry. Mounting it in the case 15 PRESSPAHN COVER CUTTING & FOLDING DETAILS 27 27 FOLD UP FOLD UP FOLD UP FOLD UP 27 27 27 Fig.6: the Presspahn insulating cover is cut from a 108 x 42mm sheet and is folded to form a box, as shown here. You will need to drill holes in the righthand section to accept the Nylon securing screws and a cable tie. microcontroller IC1 out of its socket for the time being. It’s installed later, after the power supply checks have been completed. Follow with the capacitors and trimpots VR1-VR3. Make sure the electrolytic capacitor goes in the right way around and be careful not to get the trimpots mixed up. VR1 is a 20kΩ unit while the other two are 10kΩ types. The 6-way screw terminal blocks are made up by dovetailing either two 3-way or three 2-way blocks together. These can be installed now, with their openings towards the adjacent edge of 68  Silicon Chip the board. Note that the second 6-way screw terminal block is only required for the DPDT relay version (Fig.3). Installing the LEDs The two LEDs are mounted so that the top of each LED is about 8mm above the PCB. This can be achieved by sliding a 3mm cardboard spacer between their leads when soldering them into position. Take care with their orientation – the anode lead of each LED is the longer of the two. The 3-way headers for LK1-LK4 are simply snapped off a single in-line Before fitting the PCB, you will need to drill holes in the case to accept the external leads. For mains switching, you will need to fit a cable gland at one end of the case (for the input trigger and supply leads) and a mains cordgrip grommet (to secure a mains lead) on one side of the case as shown in Fig.5. If you are not switching mains voltages (ie, you are using the arrangement shown in Fig.3), then you will need to install cable glands at both ends of the case, in line with the centres of the screw terminal blocks. Note that only the SPST 60A or 80A relay is suitable for switching mains voltages and this must be installed using the arrangement shown in Fig.2 and Fig.5. The 2A DPDT relay (Jaycar SY-4060) used in Fig.3 is not suitable for mains switching. In addition, the track spacing on the PCB is NOT suitable for mains voltages. Mains switching Fig.5 shows how to wire the unit to switch the mains. However, do NOT attempt to do this unless you are experienced at working with high-voltage siliconchip.com.au wiring and know exactly what you are doing. Make sure also that the mains cable is adequately rated for the load current. Our prototype shows a light-duty 7.5A cable in place but you must use a heavier cable for higher currents. A cord­grip grommet is used to secure the sheathed mains-rated cable to the box (for cables up to 10A). The hole for this grommet must be carefully sized and shaped so that the cord is clamped securely when the grommet is inserted into this hole. That last step is critical – if the hole is too big, the cord will not be clamped securely. As shown, the mains leads are soldered directly to the relay terminals and these must then be insulated using 10mm-diameter heatshrink sleeving. Do not bend the relay terminals as they are liable to break. In addition, it’s necessary to isolate this mains section from the low-voltage circuitry using a Presspahn cover. Fig.6 shows how to make this cover. It’s cut out from a 108 x 42mm piece which is then folded as shown to make a box. Once it’s made, you will need to drill holes in the righthand 27 x 27mm section to match the four 3mm holes (including the mounting hole) in the corner of the PCB. That done, the Presspahn cover can be attached to the PCB using an M3 x 6mm Nylon screw and nut – see Fig.5. The mains lead is then secured to the PCB using a cable tie which loops down through two of the other holes. Before finally installing the board in the case, it will also be necessary to connect the supply and trigger wiring to the 6-way screw terminal block. The PCB assembly can then be dropped into the case and secured using M3 x 6mm screws. Note that you must use a Nylon screw for the corner hole that goes though the Pesspahn (ie, the two screws used to secure the Presspahn material must both by Nylon types). Using Nylon screws ensures that the mains remains isolated from the low-voltage section of the PCB, even if one of the mains wires breaks away from its relay terminal and contacts one of these screws. In addition, a Nylon screw and an M3 x 15mm tapped Nylon spacer is attached to the side of the box, directly above transistors Q4 & Q6. This holds the side of the Presspahn material in place and ensures that it remains siliconchip.com.au The Presspahn insulation folds over to box in the mains connections. Note that one relay terminal protrudes through the side of the cover and this must be insulated using heatshrink sleeving. in position when it’s folded over to form a box and the lid attached. It also stops the Presspahn from bending and damaging the transistors. Complete the assembly by fitting the front panel label. It can be downloaded in PDF format from the SILICON CHIP website. Setting up With IC1 out of circuit, apply power (eg, from a 12V battery) to the +12V and 0V inputs and check the voltage between pin 14 of IC1’s socket and TP GND. This should be very close to 5V, ie, between 4.98V and 5.02V. If this is correct, switch off and insert IC1 into its socket, taking care to orientate it correctly. Now measure the supply voltage applied to the circuit at the +12V input. Using a calculator, divide this voltage by three. Next, use your DMM to monitor the voltage between TP1 and TP GND and press switch S2. Adjust VR1 so that the DMM reads the supply voltage divided by three value, as calculated above (eg, if the supply voltage measures 12.3V, adjust VR1 to give 4.1V between TP1 and TP GND). This adjustment sets the low-battery switch-off value to 11.5V, with the circuit then remaining in standby until the battery voltage rises to 12V. The actual voltages measured by IC1 are 3.83V for the low battery switch-off and 4V for the relay return voltage. This setting can be changed if a different low-battery switch-off voltage is required. The required voltage at TP1 is calculated simply by first dividing the required low-battery switch-off voltage by 3.83V. This value then becomes the divisor for the input supply voltage and the resulting divided value becomes the voltage setting for TP1. For example, let’s say that the required low-battery switch-off voltage is 11V. In this case, 11V divided by 3.83 = 2.87. If the battery voltage is exactly 12V, we simply divide this by 2.87 to get 4.18V. This voltage is then set at TP1 using trimpot VR1. The switch-on (ie, resume) voltage after a low voltage has been detected is now the 4V return voltage multiplied by 2.87. This gives 11.48V. Relay pulse duration Trimpot VR2 sets the pulse duration for the relay. In practice, this can be set anywhere from 0-500ms, with 1V on VR2’s wiper giving 100ms (ie, divide the voltage reading by 10). To carry out this adjustment, connect a DMM between TP2 and TP GND and press S2. It’s then just a matter of adjusting VR2 to set the recommended pulse duration for the relay. For the Jaycar SY-4060, the pulse duration required is about 25ms, so VR2 is set to give 250mV on TP2. For the 60A and 80A relays, the pulse June 2011  69 4148 – TRIGGER IN – – 0V CONTACT SET 1 11160191 + NO + + NC V+ COM 0V H CTI WS YALER G NI H CTAL +12V COM +12V NO 0V NC NO LINK LK1: LK1 sets the relay state when the battery is low. Generally, this is set so that the relay’s NO and COM contacts open when the low-battery cut-out point is reached, to remove battery power from the load. This is done by installing LK1 in position 2. If you use a different relay to the types specified, then LK1 may need 4148 WIRING AN EXTERNAL TRIGGER SWITCH DOUBLE COIL RELAY VERSION CONNECTIONS Setting the links 0V EXTERNAL SWITCH CONTACT SET 2 Fig.7: this diagram shows the external connections to the double-coil relay version. It’s suitable for switching low voltages only (up to 30VDC <at> 2A). needs to be equal to or greater than 60ms which means that VR2 should be set to give at least 600mV. V+ WIRE LINK NC COM MAXIMUM RELAY CONTACT RATING = 30V <at> 2A 4148 4004 4148 16V 4004 16V Fig.8: here’s how to wire an external trigger switch (both versions). to be placed in position 1 to achieve the same result, ie, so that the contacts are open on low battery. You can ensure that LK1 is correct by checking that the relay’s contacts open when the supply is reduced below 11.5V or if VR1 is adjusted fully anticlockwise. You will need to wait about 10s for the low-battery voltage to be detected and the relay switched. Be sure to readjust VR1 to its correct position after checking this operation, as described previously. LED1 lights briefly when the relay contacts close, while LED2 lights briefly when they open. This assumes that you are using one of the specified relays and that LK1 is in position 2. The operation of the LEDs is reversed if LK1 is placed in position 1. LINK LK2: LK2 sets the input trigger edge level. With LK2 in position 2, the relay is triggered when the input signal drops from a high level to 0V (ie, a falling edge trigger). In position 1, the relay triggers on a rising input signal, eg from 0V to 5V (or similar). If LK2 is left out, the relay triggers Table 3: Link Settings & Trimpot Adjustments Link Setting Position 1 Position 2 Open Notes LK1 Low Battery State NO contacts closed on low battery NO contacts open on low battery Not used Relay contact state with low battery LK2 Edge Triggering Triggers on high-going input & when S1 closes Triggers on low-going input & when S1 opens Triggers on both edges and when S1 closes or opens LK3 Operation Momentary with timer Toggle (or alternate) Follow input LK4 with LK3 set for Timer Mode 0-5h 0-50s 0-5m VR2 sets value LK4 with LK3 set for Toggle Mode Powers up with NO contacts closed Powers up with NO contacts open Not used Power up relay state Adjustments Use VR1 Sets low battery switching voltage TP1 monitors divided battery voltage with S2 pressed VR2 Relay pulse duration 0-500ms TP2 monitors VR2 setting with S2 pressed VR3 Timer value TP3 monitors VR3 setting with S2 pressed S1 Test operation S2 Resets timer and sets changed links and adjustments Press whenever links or adjustments are made S2 Press and hold at power up to change timer relay state Selects either NO contact closed with timer or NO contact open with timer 70  Silicon Chip siliconchip.com.au on both rising and falling edges. LINK LK3: LK3 sets the relay operation to either Momentary mode (position 1), Toggle mode (position 2) or Follow mode (no link). The Momentary mode operates with a timer. Once triggered, the relay switches on for the timer duration and then turns off again. By contrast, in Toggle mode, the relay changes state on each trigger signal. Once triggered, it remains in that state until the next trigger signal arrives. The Follow mode allows the unit to be used as a replacement for a standard relay. It duplicates the operation of a standard (non-latching) relay. LINK LK4: LK4 sets the timer range for the Momentary mode. LK4 in position 1 gives a range of 0-5 hours, position 2 gives 0-50 seconds and no link gives 0-5 minutes. The exact time-out value is set by trimpot VR3. For the 0-50s range (position 2), 1V at TP3 (with S2 pressed) gives 10s, 2V gives 20s and so on, up to 5V which gives 50s. Other voltages give corresponding timeout values, eg, 0.5V gives 5s and 2.5V gives 25s. Similarly, for the 0-5 hour range (position 1), 1V at TP3 is equivalent to 1 hour and for the 0-5 minute range (LK4 not installed), 1V at TP3 is equivalent to 1 minute. Switch S2 can be used to cancel (or reset) the time-out during timing. Any retriggering during timing will be ignored. By default, the unit is set so that during timing, the relay’s NO contact is closed. This means that the NO contacts are normally open at power up and after time-out. However, this can be changed so that the relay’s NO contact is closed at power up and open during timing. To do this, press and hold S2 for 5s during power up and the option will be set. Repeat this procedure to revert to the default mode. Link LK4 can also be used when the unit is set to Toggle mode (LK3 in position 2), to select the relay state at power-up. Installing LK4 in position 1 sets the NO contacts closed at power-up, while position 2 sets the NO contacts open at power-up. LK4 has no effect in the Follow mode. trigger the unit, so that you can test the unit without having to feed in an external trigger signal. LEDs1 & 2 indicate the relay operation. As stated, LED1 briefly lights when the relay contacts close, while LED2 briefly lights when they open. Test switch Triggering input Test switch S1 allows you to easily check the results of the above link settings. It simply allows you to manually The IN+ and IN– inputs are used to trigger the VersaTimer/Switch. The maximum trigger voltage is 35V and siliconchip.com.au Parts List 1 PCB, code 19106111, 103 x 78mm 1 115 x 90 x 55mm IP65 polycarbonate enclosure 1 12VDC latching relay (see below) 1 DIP18 IC socket 2 3-6.5mm diameter cable IP65 cable glands 2 3-way PC-mount screw terminal blocks, 5.08mm spacing 1 12-pin SIL pin header with 2.54mm spacings (broken into 4 x 3-way headers) 4 2.54mm pin spacing jumper plugs 2 momentary pushbutton 2-pin PC mount switches (S1,S2) 4 M3 x 6mm screws 4 PC stakes 1 20kΩ miniature horizontal trimpot (VR1) 2 10kΩ miniature horizontal trimpots (VR2,VR3) Semiconductors 1 PIC16F88-I/P microcontroller (IC1) programmed with 1910611A.hex 2 4N28 optocouplers (IC2,IC3) 1 MCP1703T-5002E/CB 250mA 5V low-dropout low-quiescent current regulator (REG1) 2 BC337 NPN transistors (Q3,Q4) 1 3mm green LED (LED1) 1 3mm red LED (LED2) 3 1N4004 1A diodes (D1-D3) 1 1N4148 signal diode (D4) 1 16V 1W zener diode (ZD1) Capacitors 1 100µF 16V PC electrolytic 2 1µF monolithic ceramic 1 220nF MKT polyester 1 100nF MKT polyester 4 10nF MKT polyester Resistors (0.25W 1%) 1 470kΩ 3 1kΩ 1 22kΩ 3 470Ω 2 10kΩ 1 100Ω 1 2.2kΩ 1 10Ω Additional parts for 30V 2A DPDT version 1 12VDC DPDT 2A <at> 30VDC latching relay (Jaycar SY-4060) 2 3-way PC-mount screw terminal blocks, 5.08mm spacing Additional parts for 250VAC 60A or 80A SPST version 1 12V SPST 80A <at> 250VAC latching relay [Oatley Electronics JMX-94F-A-Z (www.oatleyelectronics.com)] Or 1 12V SPST 60A <at> 250VAC latching relay [Virtual-village (www.virtual-village.com.au) or see www.virtualvillage.com.au/4-x-12v-coilpolarized-latching-relays60a-250v-ac-003602-027.html] 2 BC327 PNP transistors (Q1,Q2) 2 BC547 NPN transistors (Q5,Q6) 4 10kΩ 0.25W 1% resistors 2 1kΩ 0.25W 1% resistors Additional parts for for mains control switching 1 108 x 42mm Presspahn sheet 2 M3 x 6mm Nylon screws 1 M3 x 15mm Nylon screw 1 M3 tapped Nylon standoff 15mm long 1 M3 nut 1 cord grip grommet to suit the sheathed mains cable 1 100mm cable tie the minimum is 3.25V if the 10kΩ resistor used for R1. The trigger signal must be capable of delivering about 400µA with a 5V supply. Note that R1 should be changed to 6.2kΩ for a 3V trigger input, 3kΩ for a 2V trigger input and 1.5kΩ for a 1.5V trigger input. Note also that the triggering input is electrically isolated so that a voltage that is not referenced to the Versa­ Timer/Switch circuit can be used as June 2011  71 Latching relay A latching relay differs from a standard (non-latching) relay in that it will remain in either state (or latch) without further power. In some ways, this is analogous to a conventional household light switch – when the switch is flicked to one position, it remains there until the actuator (or switch lever) is switched back to its alternative position. However, instead of the switch lever, a latching relay uses a coil and an armature to activate the switching action. a trigger. The voltage differential between the trigger source and the Versa­ timer/Switch circuit should limited to a maximum of 50V. The triggering sensitivity is quite good. In fact, the unit can be triggered 72  Silicon Chip Fig.10(a) shows the internal construction of a latching relay. It includes two horseshoe-shaped bar magnets which are positioned between the C-shaped core (or pole pieces) of the relay coil. These two bar magnets are physically separated and attached to a pivot which allows the assembly to rotate clockwise and anticlockwise between the C-core. This pivoting assembly is called the “armature”. When the armature is in its anticlockwise position, the top bar magnet’s south pole is attracted to the top section of the currently non-magnetised C-core (or pole piece), while the bottom bar magnet’s north pole is attracted to the lower section. As a result, the armature is held in that position. Note that the bar magnets can be horseshoe shaped as shown in Fig.10(a) or they can be two straight bars with north on one face and south on the other. The latching relay depicted in Fig.10(a) is activated by applying a voltage to the coil, so that the current flows in a direction that causes the top of the C-core to become a south pole and the bottom to become a north pole. When that happens, the like south poles at the top and the like north poles at the bottom are repelled from each other. At the same time, the south pole at the top of the C-core attracts the north pole of the top magnet, while the north pole at the bottom of the C-core attracts the south pole of the bottom armature magnet. As a result, the armature rotates clockwise to the position shown in Fig.10(b). The armature now remains (or latches) in this position, even after coil current is removed. That’s because the north pole at the top of the armature is still attracted to the C-core (which becomes non-magnetised when the coil current ceases). Similarly, the south pole at the bottom of the armature is attracted to bottom pole piece of the now non-magnetised C-core. Flipping back Getting the relay to latch back into its previous position simply involves feeding a by connecting the input across an indicator LED in an external device (ie, it will trigger when the LED lights). Note, however, that R1 should be reduced to either 3kΩ or 1.5kΩ to ensure reliable triggering in this situation. FLEXIBLE CONNECTION POLE (INSIDE COIL) ARMATURE CONTACTS COIL COIL CONNECTIONS NC NO COM NON-LATCHING RELAY CONSTRUCTION A V+ RELAY NC COM NO 2 1 S1 B NON-LATCHING RELAY DRIVE V+ RELAY NC S1 C COM The most common relay is the standard non-latching type. This comprises a relay coil, an armature and switch contacts as shown in Fig.9(a). When no current flows through the coil, the relay contacts are held in their normal position by spring tension, with the NC (normally closed) contact resting against the COM (common) contact and the normally open (NO) contact left open. Conversely, when the relay is powered, the current through the coil causes the armature to be attracted to the coil’s pole piece and this moves the relay contacts to their opposite position. As a result, the COM contact closes against the NO contact and the NC contact opens. Fig.9(b) shows how a standard nonlatching relay can be driven using a switch. The switch (S1) simply connects power to the coil when it is closed. Another arrangement for the non-latch­ ing relay is when the common (COM) and normally open (NO) contacts are used together with a momentary contact switch to form a self-latching operation – see Fig.9(c). Pressing the pushbutton switch (S1) activates the relay and closes the NO and COM contacts. These contacts now form a parallel connection across S1 so that when S1 is opened, the relay coil remains energised. These closed contacts (or other con­ tacts) can also be used to power external circuitry. Note, however, that this selflatching relay circuit is not the same as a latching-type relay, since the relay continues to draw coil current. SPRING PIVOT NO Latching Relays: How They Work SELF-LATCHING RELAY CONNECTION Fig.9: internal details of a non-latch­ ing relay (A) plus non-latching (B) and self-latching (C) drive circuits. Finally, connect the inputs as shown in Fig.8 if you want to trigger the unit using an external pushbutton switch. Note that the switch current adds to the battery drain while it is pressed SC and is 1.1mA at 12V. siliconchip.com.au Latching relay variations Latching relays come in two different types: single coil and double coil. As stated, the single coil latching relay changes state depending on the polarity of the voltage applied to the coil. By contrast, a double-coil type relay uses one coil to set the contacts one way and another coil to reset them back the other way. The advantage of the double-coil relay is that fewer components are required to drive it. Fig.11(a) shows how a single-coil latching relay can be driven using a DP3P switch. In position 1, the top of the coil is at ground and the lower end of the coil is connected to the positive supply. This causes the relay to be in its reset state, with the NO contact open and the NC contact shorted to the COM contact. In position 2, no current flows to the coil while in position 3, the coil current is reversed and the relay switches to the siliconchip.com.au ACTUATOR ARM ACTUATOR ARM POLE PIECE S S RE ARM A TU POLE (INSIDE COIL) COIL PIVOT N S S POLE PIECE 2 1 OPEN COM OPEN COIL CONNECTIONS A POLE PIECE CONTACTS LATCHING RELAY CONSTRUCTION COIL CONNECTIONS CLOSED 2 COIL S N CONTACTS 1 S N PIVOT RE ARM ATU N POLE PIECE POLE (INSIDE COIL) N N CLOSED COM current pulse through the coil in the opposite direction. This forces the top pole piece to become a north pole and the bottom pole piece to become a south pole. As a result, the armature rotates anti-clockwise, back to the position shown in Fig.10(a) Note that the current direction through the coil must be correct in order to get the relay to change state. If it isn’t, the armature remains in its present position. Note also that the north and south markings for the pole pieces in Figs.10(a) & 10(b) are those that would cause the armature to rotate to the position shown. However, as stated, these poles become non-magnetised when coil current ceases. In practice, the coil current is only required for a brief period in order to move the armature to its alternative position. The current pulse can be as short as 5ms for small relays and about 60ms for larger relays. It’s both undesirable and unnecessary to have the coil energised permanently. Prolonged magnetisation of the pole pieces can cause them to become permanently magnetised (called “remanent magnetism”). When this happens, the latching action is less effective in one position (ie, where the remanent magnetism repels the attracted pole after power is removed). This also reduces the current rating of the contacts due to reduced contact pressure. As shown, the armature of the latching relay drives a lever and this in turn opens and closes the contacts. The accompanying photos also show a latching relay with the armature in its alternative positions. LATCHING RELAY IN ALTERNATE STATE B Fig.10: how a latching relay works. It uses magnets at either end of a moving armature which are attracted/repelled by the polepieces, depending on the direction of the current pulse applied to the coil. These inside photos show the two armature positions inside a single-coil latching relay. The armature remains in its last position until the next current pulse is applied to the coil (ie, it self-latches). set position. As a result, the COM contact closes against the NO contact and the NC contact is now open. Fig.11(b) shows the simpler switching arrangement that’s used for a double-coil latching relay. In this case, the relay can be controlled using a SP3P switch, with one coil driven with the switch in position 1 and the other coil driven in position 3. Finally, note that the traditional NO and NC nomenclature does not really apply for latching relays. However, the relay manufacturers still generally indicate NO and NC contacts and qualify these states as valid when a certain current polarity is SC applied to one of the coils. V+ V+ 3 S1a RELAY 2 1 3 R NC S S1b 2 S R RELAY 1 NO COM NC 2 3 COM NO S1 1 A SINGLE COIL LATCHING RELAY DRIVE B DOUBLE COIL LATCHING RELAY DRIVE Fig.11: a single-coil latching relay (A) can be driven using a DP3P switch. The switching for a double-coil latching relay is somewhat simpler since only a SP3P switch is required. No current flows through the coil(s) in position 2. June 2011  73 Marantz CD6003 CD ...high quality machine has pitch control and USB input Marantz is one of the few mainstream hifi manufacturers still making dedicated CD players. In fact, they make quite a few, ranging in price from affordable to very expensive. We take a look at a machine which is somewhere in-between, offering pitch control and a USB input so MP3 and other files can be played. T hese days, most people happily play their CDs through a DVD player, which might be a run-of-themill model or a Blu-ray player. And while the better DVD players do give a reasonable performance when playing CDs, it is certainly not the best sonic result and there are often problems with hum and other interference. It may surprise some readers just how much RF interference can be superimposed on the analog audio and video output of DVD players, particularly on the cheaper models. Sometimes this can be enough to severely interfere with AM and FM radio reception. So inevitably, using a DVD player for CDs means that you can be feeding significant RF signals into the inputs 74  Silicon Chip of your amplifier. That is bad enough but the fact that just about all DVD players are of double-insulated construction and use a switchmode power supply means that there can be significant buzz, hum and other extraneous noises to mar your enjoyment of the music. We investigated these problems fairly thoroughly in the October 2007 issue of SILICON CHIP. One way to circumvent most of the problems of DVD players is to feed the TOSLINK (optical) digital output to the digital input on a home theatre receiver but even there, the results might not be optimum. Better still is to feed the TOSLINK output to a high-quality digital-to-analog converter (DAC) and to that end, we published a high-performance siliconchip.com.au player Review by Leo Simpson DAC in the September to November 2009 issues of SILICON CHIP. This had the added feature of remote control of the volume level. Well, that solves most of the issues to do with sound quality but DVD players still have drawbacks. For example, they often take an age to power up and then recognise that they have loaded a CD. And since they tend to be designed with on-screen display of their features, they don’t do a good job of indicating CD tracks and other functions. And then, when you press PLAY or change tracks, they often have to cogitate about it for a while before responding to your command. All of this came to mind just recently when I decided I siliconchip.com.au Features: •    • • • • • • • • • • Pure high-quality CD Player with MP3, WMA and WAV playback CD-R/RW compatible; CD-text HDAM-SA2 circuitry High-quality D/A conversion (CS4398) Customised audio components Quick replay Pitch control iPod-compatible USB input Coax and optical digital outputs Headphone output with level control Dedicated remote control wanted a new CD player for my study. Having made the decision, I was immediately confronted by the limited choice on offer – just a few well-known brands and at prices considerably higher than even for a good quality Blu-ray player. But I also wanted a high-quality player with the facility of pitch control and that limits choice even further. Sure, there are some reasonably priced “professional” CD players with pitch control but these are geared more to installations in clubs and other similar venues and their audio performance is not up there with the high-quality audiophile brands. Which brought me to the Marantz CD5004. This is their “entry-level” player which does have pitch control, along with the capability to play CD-Rs, and CD-RWs and it will play CD-DA (PCM) alongside MP3 and WMA formatted files at 42, 44.1 and 48kHz sampling frequencies. As well, it has the ability to read music data on MP3s and WMA files as well as text-data encoded CDs. This means that it will show the title of each CD track as it begins playing. It also uses the Cirrus Logic CS4392 DAC chip and the HDAM-SA2, the company’s proprietary Hyper Dynamic Amplifier Modules which were originally developed for their premium Reference Series products. This means that its audio performance should be very respectable. So I checked prices and some on-line reviews, all of which were encouraging. But then I considered the next machine up in the range, the CD6003. It uses a better DAC, the Cirrus Logic CS4398 and it also has a USB socket on the front panel which means that you can plug in a flash drive, iPod or other media source so you can get a really good result when playing these files. In all other respects, it appears quite similar in features to the CD5004. Indeed, all the Marantz CD players have the same styling and general presentation with the differences being mainly confined to the internal circuitry and possibly the ability to play SACD disks. Some of the more up-market models in the range have been specially tweaked by the noted audiophile designer, Ken Ishiwata but I think he has had a hand in the design of most of the Marantz range. He really knows his stuff. So I decided to purchase the Marantz CD6003; just like that, sight unseen. When it was delivered, I wanted to see just how good it was, so I put the CD6003 through its paces on our Audio Precision test gear. And that is how this review came into being. June 2011  75 Inside the Marantz 6003; it’s as complex as we have ever seen in a CD player, with no less than seven PCBs. But beware of that unshielded mains input socket (left top) – it’s a trap for the unwary (if you ever open the case, that is!). Presentation The first aspect of the Marantz CD6003 which impresses is that it is such a substantial machine, in great contrast to the often flimsy cases and ever-diminishing scale of most DVD players. Marantz gear is bulky and solid; there is no other way to say it. And while you can have it in ubiquitous black, I much prefer the silvery sheen shown in the accompanying photos. The front panel looks to be all metal but the central section is an aluminium extrusion while the curved sections on either side are substantial plastic mouldings. Overall dimensions are 435mm wide, 104mm high and 340mm deep, including mounting feet, the front panel headphone knob and rear-mounted RCA phono sockets. Weight is a hefty 6.6kg. The disk drawer is centrally mounted above the dot matrix display. To the left of this are three pushbuttons (Open/ Close, Fast Forward, Fast Reverse), the USB socket and a tiny pushbutton which selects between USB and disk. To the left of those again is a large button for the power switch. To the right of the display panel are another three pushbuttons (Play, Stop & Pause), the 6.5mm headphone socket and the associated small knob for its volume level. 76  Silicon Chip On the rear panel is the 2-pin IEC socket for power, a pair of gold-plated RCA phono sockets for the left and right analog outputs plus another gold-plated RCA socket for the coaxial (SPDIF) digital output, a TOSLINK output socket and a further two RCA sockets for the Marantz proprietary remote control system which allows the CD player to be tied to other Marantz equipment. There is also a small slide switch to select between the player’s infrared remote control and an external control from other Marantz equipment (eg, amplifier or home-theatre receiver). The CD6003 is double-insulated, hence the 2-pin IEC power socket which accepts a standard 3-pin IEC power cord. However, the machine does not use a switchmode power supply. Instead, as becomes apparent when the top cover is removed, it uses a rather elaborate conventional linear power supply with two mains transformers, one of which is tiny, to provide the standby function. Inside, the Marantz appears to be far more complex than any previous CD player we have reviewed. No less than seven PCBs are employed. On the lefthand side of the chassis is the very large power supply board, with umpteen (well, five) regulators fitted with heatsinks. siliconchip.com.au By today’s standards the rear panel of the Marantz 6003 is positively spartan. But it has everything you need: analog out, digital audio out in both coaxial and optical (TOSLINK), provision for a wired remote control and finally, a 2-pin IEC mains socket (which fits the standard 3-pin IEC mains plug but does not have an earth pin because the unit is double insulated). Interestingly, when the unit is on standby, a minuscule red LED on the front panel is alight. Pressing the Power button closes a relay on the power PCB and switches over to the main supply. This extinguishes the red LED and lights up the dot matrix readout which momentarily displays “Power On” then “TOC reading” (indicating that it is attempting to read the table of contents on the CD). If none is present, it then says “No disc”. It then displays “CD” to indicate that it is ready for you to load a CD. Clever little blighter, isn’t it? But it is quicker to respond than a typical DVD player which can seemingly take weeks to rouse itself when it is powered up. Power consumption is quoted as 19W, dropping to a minuscule 300mW in standby mode. Looking back inside the chassis again, we were a little surprised to see that the AC terminals on the IEC power socket were bare of any insulation. Shock, horror! Now I know that the back panel carries the Caution notice “Shock hazard. Do not remove screws” (or in French: “Attention: risque de choc electrique. Ne pas enlever les vis” – nowhere near as threatening) but those terminals should still have some protection from the fingers or tools of a technician who may not be concentrating. Incidentally, the same comments apply to the copper side of the PCB which carries the terminals of the mains transformer. The centrally located PCB carries the NEC microprocessor which controls the transport mechanism, all the play functions and provides the digital outputs. The large PCB on the righthand side of the chassis is the aforementioned HDAM SA2 “Hyper Dynamic Amplifier Modules”. These are operational amplifiers designed with discrete transistors; not any of those “ghastly” op amp ICs! This comes from Marantz’s deliberate appeal to the (often screw-ball) audiophile end of the market which tends to regard even the best op amp ICs with disdain. Not that Marantz is wrong to take this approach since it is definitely possible to get better performance from a discrete design than even the best op amps. Underneath that same PCB is the surface-mount Cirrus Logic CS4398 DAC chip. Presumably, audiophiles will tolerate that; after all, you must have a DAC and if it was a discrete design it would be huge. Also of interest is the separate headphone drive amplifier which appears to be based on a surface-mount dual op amp. siliconchip.com.au This is a so-called “current buffer” which provides a low impedance drive to the headphones. All told, the standard of construction is very good with the double-thickness base plate providing extra rigidity. The CD6003 comes with a large infrared remote control and you might wonder why so many buttons are needed; there are no less than 41! Funnily enough, each one has a function but as we subsequently found, some of those could have been arranged differently. Operating it Using the Marantz CD6003 is a dream compared to the average DVD player, in that it responds much more quickly, as mentioned above. It powers up quickly and if you place a CD on the tray and press the Load/Eject button, it immediately retracts the drawer and then reads the disk’s table of contents, giving a message on the readout “TOC Reading”, followed by the number of tracks and the total playing time. That takes about 10 seconds; a bit slow for a CD player but at least you know that the machine is actually doing something rather than seemingly confused, as seems to happen when a CD is fed into a DVD player. Pressing Play or selecting a track number with the remote control starts playing that track within two seconds. Indeed, anything you do with the remote elicits a response within one or two seconds. By the way, the player can cope with any number of tracks up to 99. Some CD and DVD players are very limited in this respect. If you want to find a particular track on a CD, you just press “AMS” and this plays 10 seconds of music from each track, in succession. When you find the track you want, you just press Play to continue. And of course, you can play the tracks in random fashion, repeat sections, tracks or the whole disk. Or you can program the order, delete some tracks and various other functions which most users will probably ignore. EX playing modes Audiophiles can be very “thingy” about CD players and their various functions and one of the things they have apparently learnt is that the internal microprocessor and display readout and even the digital outputs can degrade the analog audio output on CD players. This is true for some audio equipment and Marantz, seekJune 2011  77 ing to keep these fanatics (er, audiophiles) happy, gives the user the option to turn off the digital outputs and the display, using the Sound Mode button. And interestingly, various reviewers have noted that the sound quality improves noticeably. Well, that is balderdash, to put it politely. Our tests show that it makes not one iota of difference – not even a poofteenth of a percent. In fact, the only difference we could detect when “Audio EX” mode is selected (which kills the digital outputs and the display during playback) was that it prevented some remote control functions, such as selecting the next track with the “next track” button. As already noted, the CD6003 provides pitch control and this can be incremented or decremented in steps of 1% to a maximum of ±12% by pressing the appropriate buttons on the remote. Annoyingly, this kills the digital outputs and these can only be re-enabled by pressing the Reset button to kill the pitch variation. So what if you want to listen to the Marantz with pitch control and via the digital output to a hometheatre receiver? Too bad – Marantz won’t let you and yet it is possible. More annoying still is that the remote has buttons for volume control but you can only have that feature if you have the player linked to a Marantz integrated amplifier. Now this is really silly since the Cirrus CS4398 DAC is set up for digital remote control and would give a higher quality result than when the analog outputs are connected to a Marantz amplifier with its own remote control of volume. While we’re in complaint mode, we should also note that any playback from USB flash drive etc is only available from the analog outputs of the player; so no digital output. So again, if you want to listen to music files on your flash drive via TOSLINK/SPDIF to your home-theatre receiver, you will have to find another way. The good stuff. . . Having got those complaints out of the way, we can talk about the good stuff – and there is plenty of it! One point we have noticed about good-quality CD players is that they typically cite their frequency response as 2Hz to 20kHz but with no tolerance limits. The Marantz CD6003 is the same. And typically, CD test discs do not put out frequencies below 20Hz. So what is the frequency response of the CD6003? To answer this question, we produced our own test CD, with sinewave signals down to 1Hz. And how far down was the response at 1Hz? 0dB. In other words, it is ruler flat down to almost DC. Incredible. At the high end though, it starts to roll off very slightly above 10kHz and is -0.6dB down at 20kHz. We would have preferred considerably less roll-off; say no more than -0.2dB. Where the Marantz CD6003 really shines is in its figures for total harmonic distortion. This is quoted at .002% at 1kHz, a typical CD player spec. We measured around .0015% at 1kHz but we also found that it varied very little from that figure over the whole frequency range from 20Hz to 20kHz. Not that we could easily measure that performance on the Audio Precision because of the necessity to change filter bandwidths (22kHz, 30kHz and 80kHz) depending on the frequency being measured. Not only that but the Marantz does have some residual switching artefacts in its analog outputs at a level of -60dB. 78  Silicon Chip However, we managed to get meaningful harmonic distortion figures by using the averaging mode on the Agilent DSO7304A digital scope to remove high frequency noise and switching artefacts. At lower signal levels of -30dB and below, the Marantz is similarly outstanding. For example, at 1kHz and -30dB, the THD is .04% with a filter bandwidth of 22Hz to 22kHz. At -40dB it degrades to about 0.14%; still an impressive result. Baffling! To say that we were impressed with the harmonic distortion performance is understating the case. It is so good we were baffled. It is better than the specs for the Cirrus CD4398 when handing 16-bit PCM signals. Which raised the question: is Marantz converting the data stream off the disk to 24-bit to get the higher performance which is then possible from this DAC? Possibly but we did not have time to investigate this point. Clearly, in terms of overall distortion performance, this is the best CD player we have tested. Linearity of the DAC was good but not the best we have tested. There is no error down to -80dB but at -90db, it produced -88.5B at 1kHz; an error of +1.5dB. By the way, this measurement was done via the Audio Precision passive audio brickwall filter so no sampling artefacts would have degraded this measurement. We also checked signal-to-noise ratio and channel separation. For S/N ratio we measured -103dB unweighted (22Hz to 22kHz) and 110dB A-weighted. The reason for the improvement with A-weighting is that there is a very low residual level of hum in the outputs; Aweighting filters that out. Separation between channels is quoted as -100dB, with no frequency limits. We measured typically -102dB across the spectrum; reducing slightly to -99dB at 20kHz, an excellent figure. Finally, we decided to test the front panel headphone output which has its own volume control. This has a quoted maximum output level of 18mW into 32-ohm headphones but no other specs. Since we have recently been designing a high-quality stereo headphone amplifier, we just happened to have a suitable set-up for testing into various loads; very convenient. Suffice to say that the headphone amplifier appears to be not quite up to the same very high standard as the rest of the player. But it is still very respectable and has adequate drive for headphones of various impedances and sensitivity. THD is around the .002% mark while the S/N ratio is -104dB; a smidgen better than the main analog outputs. Separation between channels was around -75dB and channel matching about 1dB; mainly a function of resistor tolerances and the miniature ganged volume control. In use? The Marantz performs impeccably. The transport mechanism is very smooth and always quiet – a pleasure to use. And the sound quality is very high – no complaints at all. It is certainly a high-quality machine. Recommended retail price is $899. For further information, contact your hifi retailer or the Australian distributor for Marantz products: Qualifi Pty Ltd, 24 Lionel Road, Mt Waverley, Vic 3149. Phone (03) 8542 1111. Website: www.qualifi.com.au SC siliconchip.com.au siliconchip.com.au June 2011  79 By JIM ROWE A Handy USB Breakout Box You can build it in 10 minutes and for less than $15 USB is a great interface but it is isn’t foolproof. The good thing is that you can troubleshoot it with this simple USB “breakout box”. It connects into virtually any USB 1.1 or USB 2.0 cable and lets you examine D+ and D- signal line activity with your scope – as well as letting you check the USB power line voltage (Vbus) and even the current being drawn from the bus. R ECENTLY, I’VE BEEN working on the development of a USB device, ie, a device designed to hook up to a PC via a USB cable and become a “bus powered peripheral”. Along the way, I realised that I was going to have to measure the current drawn by the device, to make sure it conformed to the USB specification. Since I also struck trouble getting the device to “enumerate” properly when it was first hooked up to a PC, it was also going to be handy to be able to check the voltage levels on the two USB signal lines with my scope, to see if the voltage levels were within specification. Now since the device’s USB connector was mounted directly on its PCB, the only way to measure the current drawn from the host via the USB bus would be to cut the pin 1 track on the board, so I could connect in a milliammeter. But I didn’t want to cut a track on the board just for this test, because it would need to be bridged again with a short length of wire afterwards. It also turned out to be a bit tricky connecting my scope’s probes to the two USB signal lines, because my 80  Silicon Chip board was fairly small, with a high component density near the USB socket. In fact, this is always the way with USB interfaces – they’re hard to get at. What I really needed was a small “breakout box” which could be connected in series with the USB cable between the PC and the device. This would make any of the bus lines available for testing. So I knocked one up using a small piece of PCB cut from an old prototype board. The latter already had a USB type-A socket mounted on it, so all I had to do was add a type-B socket and a handful of other parts. It looked a bit untidy (as you can see from the above photo) but it worked well and let me do the testing in short order. When I mentioned that I had built up this handy little USB testing jig to SILICON CHIP’s esteemed publisher Leo Simpson, his response was as quick as a shot: “If it’s that handy why don’t you take a quick picture of it and draw up the circuit, so we can publish the details in the magazine and give other people the chance to build one?” In the end, as well as taking a few photos and drawing up the circuit, I also designed a PCB pattern for it. So when you build one, it will look better than my prototype. What’s more, it will take take just 10 minutes or less to put together. Circuit details Fig.1 shows the circuit and there really is very little to it. All four USB lines basically pass “straight through” between the type B input socket and the type A output socket, so normal operation can continue. The Vbus line has a 1Ω 1% resistor connected in series with it but this is normally shorted out by a jumper shunt (JP1). When you want to measure the current being drawn from the host PC by the USB device, you simply remove the jumper shunt and connect a DMM between the two ends of the resistor. The resistor then acts as a current shunt, converting milliamps into millivolts. So by switching your DMM to its lowest DC voltage range (say 0-2V), you’ll be able to measure the device current in milliamps very easily. If you want to measure the bus siliconchip.com.au CON1 (USB TYPE B SOCKET) + + – – FROM PC 3 SCREEN 4 2 D– 2011 1 2 D+ TO USB DEVICE 3 4 GND GND D– D+ GND Silicon Chip Binders REAL VALUE AT $14.95 PLUS P & MONITOR D+ MONITOR D– SC  CON2 (USB TYPE A SOCKET) 1  1% Vbus 1 MEASURE Ibus* JP1 SCREEN MEASURE Vbus P * WHEN JUMPER SHUNT IS REMOVED (1mV = 1mA) USB BREAKOUT BOX Fig.1: with jumper JP1 in place, all four USB lines basically connect straight through. The current is measured by removing JP1 and monitoring the voltage across the 1Ω resistor (1mV = 1mA). Fig.2: the PCB will only take about 10 minutes to assemble. Don’t forget to solder the earth lugs on the sides of the USB sockets. The board can be fitted with rubber feet at the corners, or you can cut out the corners and fit the board into the base of a UB-5 zippy box. X O B TU OKAER B BSU 1102 © 11160140 GND D– USB IN CON1 3 2 4 1 USB OUT CON2 D+ GND 4 3 2 1  1% + – Vbus + 1 JP1 – Ibus (1mV = 1mA) WITH SHUNT REMOVED These binders will protect your copies of S ILICON CHIP. They feature heavy-board covers & are made from a dis­ tinctive 2-tone green vinyl. They hold 12 issues & will look great on your bookshelf. H 80mm internal width H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! voltage as well, this is easily done by connecting your DMM (set to the next higher DC voltage range) to the two pins of the other SIL pin strip (Vbus) on the top left of the circuit. In most cases, you should get a reading of +5V, unless there’s a problem. The two SIL pin strips near the bottom of the circuit are provided so you can easily monitor the D+ and D- signal line waveforms with an oscilloscope. As you can see from the scope grabs (Fig.3, Fig.4 & Fig.5), these signals take the form of bursts or “packets” of data at 1ms intervals. The data is encoded using a differential NZRI (non-returnto-zero inverted) format, with the D+ and D- lines pulsing in synchronism but with reversed polarity. To conform to the USB specification, both data line signals should have a peak-to-peak amplitude of between 3.0V and 3.7V. Note that while the outer screens of CON1 and CON2 are connected together, to preserve the continuity of the USB cable screen, they are not connected to the USB cable ground (ie, pin 4) inside the breakout box. This is necessary to make sure that the box doesn’t disturb the operation of the siliconchip.com.au Parts List 1 PCB, code 04106111, 76 x 45mm 1 PC-mount USB type B socket (CON1) (Jaycar PS-0920 or Altronics P1304) 1 PC-mount USB type A socket (CON2) (Jaycar PS-0916 or Altronics P1300) 1 1Ω 1% 0.25W resistor 1 SIL 8-way pin header strip 1 jumper shunt 4 self-adhesive rubber feet Price: $A14.95 plus $A10.00 p&p per order. Available only in Aust. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or call (02) 9939 3295; or fax (02) 9939 2648 & quote your credit card number. Use this handy form Enclosed is my cheque/money order for $________ or please debit my screen in USB 2.0 cables. I should note here that the main information you’ll be able to get from the D+ and D- waveforms is their peakto-peak amplitude, whether they are switching in the correct differential fashion and whether they’re both fairly constant in amplitude rather than varying sporadically or cyclically – either of which are indications of problems. It’s not easy to get much more information than this because of the differential NZRI encoding.  Visa    Mastercard Card No: _________________________________ Card Expiry Date ____/____ Signature ________________________ Name ____________________________ Address__________________________ __________________ P/code_______ June 2011  81 Fig.2 shows the assembly details. It’s just a matter of installing the parts as shown, not forgetting the wire link. The four 2-way pin headers are snapped off an 8-way header. The corners of the board can be fitted with rubber feet or it can be mounted in the base of a standard UB-5 zippy box. In use, jumper shunt JP1 is removed if you want to measure the voltage across the 1Ω resistor, to determine the current drawn by the attached USB device. Protocol analyser Fig.3: a single USB control packet showing the differential NZRI encoding (D+ in yellow and the D- in blue). The frequency reading is not relevant but note how the two waveforms have approximately equal P-P amplitudes. Fig.4: another capture of the D+ and D- signal waveforms, at a slower time­ base rate. Here we see a control packet, followed by a much longer data packet. Again the frequency reading is not relevant. Fig.5: this third capture of USB signal waveforms is at a much slower rate again, and shows the way the D+/D- data packets are sent at intervals of 1ms. Again, the frequency reading is not relevant. 82  Silicon Chip Like most tools, the breakout box is handy for what it does but inevitably has its limitations. For examining USB bus operation in more detail once you’ve checked the basics, you really need a USB protocol analyser which can look at all of the control and data packets flying back and forth along the bus, identify those coming from the host and those returning from the device. This will let you see what’s happening (or not happening, when it’s supposed to). There are a few software USB protocol analysers currently available, which can be very handy for this “deeper” level of troubleshooting. As the name suggests, these are basically software programs which run on the PC and “keep an eye” on the activity at any designated USB port, so that they can either display it in “real time” or save all of the information in a log file which you can open later and examine in detail. One of these software USB protocol analysers I can recommend is USBTrace, developed and marketed by a firm called SysNucleus. A free 15-day evaluation copy of USBTrace can be downloaded from their website at www.sysnucleus. com and although it’s a bit restricted in terms of the data it can save during a single session, it’s still quite handy. If you want the full version, this can be purchased online for US$195.00. Also available for free downloading are software decoders for the various USB device classes, so USBTrace can be more informative about their operation. There’s also a Microsoft “USB Device Viewer” software tool called UVCview.exe which can be quite handy when you’re troubleshooting USB device operation. It’s part of Microsoft’s Windows Driver Kit (WDK), which can be downloaded for free from www.microsoft.com/downloads/ The latest version at the time of writing is V7.1.0, which comes as a 618MB ISO file. This must be burnt to a CD-R before SC UVCview can be installed. siliconchip.com.au 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. Wireless doorbell relay driver This circuit is a novel way of using a cheap wireless doorbell (available from eBay or from a discount store) to control a relay. In operation, a battery-powered doorbell receiver is used to trigger a 4027 flipflop (IC1a) that’s connected to toggle its outputs on each clock input. The doorbell receiver has an output signal that changes state on receipt of a doorbell transmission. It’s usually high when the doorbell pushbutton transmitter is pressed and low otherwise. This signal clocks flipflop IC1a to turn the relay on or off via transistors Q2 & Q3. The circuit is powered from a 5V rail which is reduced to a nominal 4.5V via diode D1 to also power the doorbell receiver. The circuit controls a 24V relay which is powered from a separate 24V supply rail. Thomas Drage, Bassendean, W.A. ($50) Microphone adaptor for a violin This adaptor was devised to enable me to play violin with a small dance band. It amplifies my instrument using one of the microphone inputs on their sound equipment. As shown, an electret microphone is coupled to a 5kΩ potentiometer via a 22µF electrolytic capacitor. The potentiometer sets the signal level into a 600Ω isolating transformer which then drives a balanced microphone input via an XLR socket. The electret insert was secured within some sponge foam under the fingerboard and connected to a 3mm jack socket fitted in the rear of the violin. A long audio cable connects the violin socket to the adapter which is housed in a small jiffy box. siliconchip.com.au +4.5V TO DOORBELL Rx BOARD +24V IN D1 +4.5V APPROX 100nF K +5V IN A 120 1.8k A LED1 A  LED2 FROM DOORBELL Rx BOARD 6 1k 3 5 10nF 7 SD1 J1 16 Vdd 1 Q1 Q1 K1 RD1 4 K 10k E B CP1 IC1a 2 A  K 24V RELAY K D2 10k C B E Q1 BC547 B Q3 PN200 C C Q2 PN100 E IC1: 4027B 10 13 11 J2 BC547 9 SD2 Q2 LEDS 15 CP2 IC1b K2 Q2 RD2 Vss 12 8 B K A 14 E D1, D2: 1N4004 A K C PN100, PN200 B C E Fig.1: this circuit alternately toggles the relay each time the doorbell button is pressed. Note that you must use a battery-powered doorbell receiver (ie, NOT directly mains-powered) to provide the input signal. 2.2k ELECTRET MIC INPUT UNBALANCED AUDIO OUT 22 F T1 VR1 5k 1.5V CELL 600 /600  2 It runs from a single 1.5V AA cell in a battery holder attached inside the box with double-sided adhesive tape, as is the transformer. Power is disconnected when the cable jack from the violin is removed from the 3mm socket. Editor’s note: for best results we 3 1 XLR BALANCED AUDIO OUT suggest the use of a good quality 600Ω isolating transformer such as Altronics M-0709 or M-0707. This type of transformer was used in the passive DI box (SILICON CHIP, May 2006) with excellent results. Colin Christensen, Redcliffe, Qld. ($45) June 2011  83 Circuit Notebook – Continued S1 START TO STARTER CONTACTOR VIA NEUTRAL SWITCH TO FUEL GAUGE, TACHO, ALT INDICATOR, FUEL PUMP & OTHER INDICATORS OIL LOP A A  K 2.2k  K 2.2k S2 RUN TEMP +24V A 2 x 470  1W +12V  K K ZD1 12V 1W 10k 2.2k RLY1 K D8 470 F 25V A 24V BATTERY A K A D5 120k 14 1 K IC1a START SIREN IC1b 2.2k 22k FUEL RACK WATCHDOG A ON A K  LED D2 A 5 D3 K 4 D6 A K 2 3 A D1 K IC1: 40106B D4 100k 6 9 IC1d 8 4.7k 7 10 F 16V 1M A IC1c Q1 MTP3055 OR S IRF630 K D G 47k RLY2 K D7 OIL LOP TEMP A STOP S3 11 IC1e 10 13 IC1f 12 MTP3055, IRF630 LEDS D1–D6: 1N4148 A K D7,D8: 1N4004 ZD1 A K A K Diesel engine watchdog circuit monitors oil pressure & water temperature This watchdog was devised after I destroyed a Caterpillar diesel engine when a stick harpooned an oil filter. Ear muffs meant that I did not hear the alarm or the disintegrating metal. Mud on the dashboard obscured all indications and gauges. The watchdog shuts down the fuel line to the injectors in the event of a fault condition being detected, turning off the engine and preventing damage. It is wired in place of the ignition switch. It works as follows: to start the engine, first the “run” switch S2 must be held down for a short period. This connects the watchdog circuit to the 24V battery. A 12V rail is derived from the 24V supply by zener diode ZD1, bypassed with a 470µF capacitor and supplied via two 470Ω 1W 84  Silicon Chip current-limiting resistors. This rail powers IC1, a quad Schmitt-trigger input inverter. The “oil”, “lop” & “temp” switches shown at the lower left of the diagram are the fault sensors and assuming there are no faults, they are all open-circuit. If so, the 10kΩ resistor pulls the input of IC1a high via a 100kΩ/120kΩ resistive divider. This divider prevents IC1a’s input from exceeding 12V. Clamp diodes D4 & D5 further protect it from excessive voltage. As a result, IC1a’s output is normally low which means that inverter stage IC1b’s output is high. This charges the 10µF capacitor at IC1c’s input via a 22kΩ series resistor and diode D6. Once that capacitor has charged K A G D D S sufficiently, the output of IC1c goes low and therefore the output of IC1d goes high, turning on Mosfet Q1 via a 4.7kΩ resistor. This energises the coil of relay RLY1, which has a diode (D8) across it to absorb any switch-off spikes. When S2 is first pressed, power is applied to the start siren, so it sounds. Once RLY1 is energised, the siren is disconnected from the 24V rail. At the same time, the “watchdog on” LED lights to indicate that the watchdog circuit is operating. RLY1’s second set of contacts closes across S2, shorting it out and so latching the 24V power on as long as the watchdog operates. At this point, the start switch (S1) can be pressed. Assuming that the transmission is in neutral (and thus the “neutral” switch is closed), power is applied to the contactor and so the engine starts. siliconchip.com.au BEAT RATE VR1 100k B 4x10k 1 7 10k 6 B C Q1 BC337 5 4 E 3 2 4.7 F 16V 1 2 3 IN1 OUT4 IN2 IN3 IC1 OUT3 PICAXE-14M OUT2 8 9 B 10 11 A A  12 IN4 OUT1 SerIN SerO/ 13 OUT0  K K A A  C LED4 LED3  K K E Q3 BC327 100nF 22 F 16V 4.5V BATTERY (3 CELLS) LED2 10 LED1 14 PROG SOCKET 4 BEAT SELECT OUT5 S2 0V 22k 10k IN0 ON/OFF Q2 BC337 E 1k +V C 8 SPEAKER 220 10k S1 LEDS PICAXE-based metronome with accented beat This metronome is based on a PICAXE14M microprocessor and includes an accented beat function. This allows the musician to select a different sound on every second, third or fourth beat. General operation of the metronome is under control of the PICAXE software and you can find out more by reading the comments in the program listing. In previous articles in SILICON CHIP, Stan Swan nominated the PICAXE as the new 555 timer and perhaps this circuit proves his point by functioning like the classic 555 astable multivibrator. The 4.7µF capacitor at the base of transistor Q1 is alternately charged and then discharged by output 5 of the PICAXE If at any point one of the sensors registers a failure, its corresponding warning LED is switched on. At the same time, the input to IC1a is pulled low via the 100kΩ resistor and the diode connecting that sensor line to it (D1, D2, D3, etc). More sensors can be added, simply by connecting more diodes and LEDs in the same manner as shown. When a sensor activates, this also completes the circuit for the coil of relay RLY2, switching it on and thus powering a solenoid that cuts fuel to siliconchip.com.au (pin 8) and associated components, working between upper and lower threshold levels established by input IN4 (pin 3). Within the program, input IN4 is operated in the A/D converter mode, allowing accurate setting of the two threshold levels. This means that the 4.7µF capacitor provides the basic beat of the metronome, with potentiometer VR1 varying the capacitor charge and discharge currents to set the beat rate. Emitter follower Q1 is used as a buffer between the capacitor and the PICAXE input. If you require a slower beat rate, just increase the value of the capacitor. Switch S1 selects continuous or accented beat operation while the the injector rail, shutting down the engine. Then after a second or two, the 10µF capacitor at the input of IC1c discharges enough for IC1c’s output to go high, ultimately turning off Mosfet Q1 and thus RLY1, shutting the watchdog down entirely. The watchdog can also be shut down by pressing the “stop” button (S3) which has the same effect as a sensor operating. The type of solenoid to use depends on the engine being controlled. Diode D7 quenches any in- K A BC327, BC337 B E C four LEDs are included to give a visual display of the selected beat. Output 4 (pin 9) drives the complementary transistor buffer (Q2 & Q3) and the 8-ohm loudspeaker which is coupled via a 22µF capacitor. The normal ticking sound and also the accented beat sound are actually short bursts of audio tone and not just a single pulse, as this gives a much louder and more effective sound. The speaker should be mounted in an enclosure or you will not obtain maximum loudness. The software, Metronome_pgm. bas, can be downloaded from the SILICON CHIP website. Ian Robertson, Engadine, NSW. ($80) ductive spikes when RLY2 switches off. Since the watchdog shuts down completely after the engine is cut, it can be used unattended (eg, for engine-driven pumps) and will not discharge the battery after a fault. Note that this circuit may not be suitable without modification for turbocharged engines as it may be necessary to idle the engine for a period before shutting it down. Merv Thomas, Townsville, Qld. ($80) June 2011  85 Circuit Notebook – Continued Multi-decade period-multiplier for precision frequency comparisons This circuit was built to enable very precise calibration of a Rubidium Frequency Standard unit against a GPS-derived frequency standard. It uses the 1-pulse/second signal from a GPS-based frequency reference to generate a very accurate long-duration gate-control pulse for a frequency counter. The GPS-Based Frequency Reference (SILICON CHIP, March & April 2007) or a commercial unit (eg, Trimble Thunderbolt) would be suitable. The signal to be calibrated or compared would typically be 10MHz from a stable oscillator. A 7-digit frequency counter with a 1-second gate period will have a resolution of 1Hz, being one part in 107 for a 10MHz signal. If the gate time is increased to 10 seconds, the counter will repeatedly overflow but the resolution will become 0.1Hz, giving one part in 108 for a 10MHz signal. The Multiplier can extend the resolution to one part in 1013, averaged over one million seconds (just under 12 days). I used a Hewlett Packard 5301A 7-digit counter which has a TTLlevel gate input. Many other frequency counters would also be suitable. The circuit uses mostly 4000series CMOS ICs. The 1-pulse/second GPS signal is fed into a 4584B non-inverting Schmitt trigger buffer (IC1a,b) and then to a chain of six 4017B decade counters (IC2-IC7). A 7-position switch (S3) selects the output from the Schmitt buffer or any of the decade counters. This switched output triggers a D flipflop (4013B) which will change state every 1, 10, 100, . . . or one million seconds, as chosen. The Q output of the 4013B (IC9b) drives a complementary transistor pair to give a low impedance output to drive the counter gate. The Hewlett Packard counter gate is open on LOW but if another counter required a HIGH to open, the Q-bar output would be used instead. Note that the gate is open for every alternate counter period. The 9-to-0 transition of each counter advances the next-higher counter by 1 and when selected by the 7-position switch is used to toggle the flipflop. A reset switch sets all counters to zero and sets the 4013B to close the frequency counter’s gate. Thereafter, the gate will not open until after one complete count period. This could be 11 days later! Therefore, a 7555 variable-frequency oscillator with a wide frequency range (set by potentiometer and range switch) has been included. The oscillator is only active and connected to the counter input while its pushbutton is held on. It allows the counter chain to be pre-loaded to near the end of its period. Each of the 4017B counters has a LED connected to its “9” output pin; it lights only on a count of 9. The circuit must run off a +5V power supply in order to ensure a correct TTL output signal. Current drain is around 30mA, depending on which LEDs are lit. When using the Multiplier, only those counters up to the decade selected by the 7-position switch should be pre-loaded to “9” but do not let the two least significant counters reach “9” after the relevant more-sig- Garth J enk is t h is mont inson nificant of a Pe h’s winner digits are a Test Ins k Atlas set to “9”. trumen t Slow the os- cillator down as you approach the end o f p r e loading. It is too easy to overshoot and start the count by mistake! If this happens, use RESET to stop the count, clear the frequency counter display and pre-load again. It is vital that the Multiplier be started only by a correct GPS 1-second pulse. The Hewlett Packard 5301A counter does NOT clear its display before starting to count when its external gate control is used. Therefore, be sure to clear its display manually before making any measurement. I also found that my HP counter has a slight additional delay (~0.6µs) when opening compared with closing its gate but only when using the external gate control. The result is always that it loses six cycles of a 10MHz signal for any counting period. This effect can be easily identified and overcome as follows: feed the GPS 10MHz output into the frequency counter and observe the displayed value for repeated periods of 1s, 10s and 100s (or more). In every case, the display should be “0000000” ±1 count. In my system, I always obtained 9999993 or 9999994. The solution is to add “6” to the least significant digit displayed after any measurement, regardless of the selected measuring period. I have used this circuit to set a Rubidium frequency standard to within three parts in 1012 against a Trimble GPS Standard, with very good repeatable measurements, using five decades. Garth F. Jenkinson, Emerald, Vic. Contribute And Choose Your Prize We pay for each of the “Circuit Notebook” items published in SILICON CHIP but there are three more reasons to send in your circuit idea. Each month, at the discretion of the editor, the best contribution published will entitle the author to choose a prize: an LCR40 LCR meter, a DCA55 Semiconductor Component Analyser or an ESR60 86  Silicon Chip Equivalent Series Resistance Analyser, with the compliments of Peak Electronic Design Ltd – see 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 silicon<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. siliconchip.com.au siliconchip.com.au June 2011  87 VR1 500k 1k 2.2k 5 3 S2a 1 +5V 7 4 2 4 6 2 7 10k IC1b 14 IC1a IC8 7555 8 +5V 3 1 10k S4 16 Vdd 470nF S2b 8 O5-9 12 O0 O1 O2 O3 O5 O6 O7 O8 O9 1 5 6 9 11 3 2 4 7 IC2 4017B O4 10 CP1 Vss CP0 MR 4.7nF 10k 13 14 15 LEDS 1& 2: GREEN; LEDS 3 & 4: YELLOW; LEDS 5 & 6: RED 1Hz PULSES FROM GPS (N/C) S1 RESET K (IC3) 12 9 5 13 IC1f IC1e IC1d IC1c 14 3 5 (IC4) 15 6 MR R 4 IC9a S CLK D 12 IC3, IC4, IC6: 4017B 12 10 8 6 IC1: 4584B 11 14  LED1 A 1k 15 Q Q 13 MR 16 Vdd 8 0 1 1 5 6 9 S3 3 3 2 4 7 4 5 6 K 11 9 14 A K 8 12 12 14 Vdd 13 Q IC9b S (IC6) 15 Q CLK Vss R 10 7 D  LED4 A 1k D1, D2: 1N4148 IC9: 4013B MR 2 O5-9 12 O0 O1 O2 O3 O5 O6 O7 O8 O9 11 IC5 4017B O4 10 CP1 Vss CP0 2 1 14 15 A K 13 16 Vdd D2 22k 22k D1 8 1 5 6 9 11 3 2 4 7 47 47 B 100k K A K A B 100k O5-9 12 O0 O1 O2 O3 O5 O6 O7 O8 O9 IC7 4017B O4 10 CP1 Vss CP0 MR LEDS 14 15 E C C E K A  LED6 1k E B C BC549, BC558 Q2 BC549 OUT TO COUNTER (GATE INPUT) Q1 BC558 220 F 10V +5V PRODUCT SHOWCASE Quick Circuit PCB Prototyping System from SATCAM The Quick Circuit Model 3000 PCB Prototyping system provides a cost effective alternative to other rapid prototyping machines. Its small footprint and economy pricing make this machine ideal for the educational, R&D laboratory and “lessfrequent-user” markets. As the first Quick Circuit machine of its size, the Quick Circuit 3000 PCB Prototyping system is a real space saver for cramped environments, and weighs in at just 13kg. The Quick Circuit Model 3000 PCB Prototyping system offers all the customary Quick Circuit precision and repeatability in a compact integrated package. As with other Quick Circuit models, the Quick Circuit 3000 comes with a fully-featured licence to IsoPro and has the flexibility to perform precision engraving and machining of control and enclosure panels and labels, as well as its primary application of milling prototype circuit boards. Although compact, the Quick Circuit 3000 PCB Prototyping system includes standard features such as USB interface and LED work area illumination, while options include pneumatic Z-axis drive, sound enclosure, “TraceCAM” work area camera, “QC-key” machine control keypad, DXF import, G-Code exContact: port and more. Quick Circuit SATCAM is designed and 823 Victoria Road, Ryde NSW 2112 manufactured in Tel: (02) 9807 7081 Fax: (02) 9807 7083 Website: www.marantz.com.au the USA. Visaton miniature speakers fit where most speakers don’t! German loudspeaker specialist Visaton now have a large range of miniature speakers suitable for medical, industrial, projects, signalling, communications & model construction and more. Starting at a tiny 16mm in size these speakers can be put into some of the smallest spaces Inmarsat Satellite Phone from Av-Comm with excellent performance. They come in a range of shapes, sizes and impedances and are suitable for where space is at a premium. Models include various sizes such as 23mm, 28mm, 36mm, 50mm and more; PCB mount, terminals or wired options are available. They say mobile phones cover 96% of the Australian population. What they don’t say is that 96% is in about 4% of the continent! When you go “bush” or sailing or... wherever a mobile phone won’t reach,   a satphone will! Calls are fairly expensive (~83c/minute) but if you really do have to make that call, what price is too high? Av-Comm have available this prepaid Inmarsat phone, complete with soft case and charger, for $900 inc GST, plus delivery. This Contact: includes 100 call cred- Av-Comm its (~100 minutes) with PO Box 225, Brookvale NSW 2100 two year expiry (re- Tel: (02) 9939 4377 Website: www.avcomm.com.au newable, of course). 88  Silicon Chip Contact: Soundlabs Group PO Box 276 Campbelltown NSW 2560 Tel: (02) 4627 8766 Fax: (02) 9807 7083 Website: www.soundlabsgroup.com.au Zigbee Wireless Sensors The Zigbee Wireless (IEEE 802.15.4 protocol) modules from Ocean Controls can be used in applications such as industry and building automation where wide-area monitoring or control is required. The modules operate in the 2.4GHz license-free band and have a range of 120m (line of sight). This distance can easily be extended by the use of routers. The modules can be quickly configured into a Tree-type structure with a PC connected to a central coordinator and routers allowing the I/O modules to be distributed around a factory or compound. The I/O modules feature a temperature/humidity unit, analog input/output units and digital input/ output units. Ocean Control’s ISEE-Modbus TCP software can monitor and control the modules from a PC. Prices start at Contact: $149+GST for the Ocean Controls Wireless I/O modules PO Box 2191, Seaford BC, VIC 3198 and ISEE-ModbusTCP Tel: (03) 9782 5882 Website: www.oceancontrols.com.au software. siliconchip.com.au Altronics’ versatile stereo audio mixer suits professional or home use If you’re looking for an audio mixer to suit just about any application, this one from Altronics could be just the shot! With up to nine input sources (four main channels are stereo) and five output channels, this stereo mixer also offers variable echo, repeat and delay, a three-band graphic equaliser, fader controls between channels two and three and a program cue selector allowing a DJ to cue upcoming tracks via headphones. As you’d expect, each channel has its own level adjustment and there’s a master level control as well. Each of the four stereo inputs can be switched via the front panel from mic level (1.5mV/10k) to line level (150mV/22k), It suits a variety of uses from pro-style DJ work, public address systems, dubbing audio onto home videos, karaoke . . . in fact, just about any audio mixing application you RS Components catalog: get it three ways! RS Components have released their new 2011 catalog – and it’s available in three formats: (1) traditional printed version; (2) digital (CD) version and (3) online version. There are over 75,000 products in the new catalog, with all products in stock and available for immediate delivery. All 450,000 products in the Contact: RS range may be RS Components accessed online, 25 Pavesi St, Smithfield NSW 2164 with RS online in- Tel: (02) 9681 8558 Fax: (02) 9681 8614 trodcing new prod- Website: www.rsaustralia.com ucts every month. SparkFun Electronics creates Department of Education Lots of Aussie electronics enthusiasts order difficult-toobtain or oddball parts online from SparkFun Electronics, a US company specialising in helping electronic enthusiasts get the parts and resources they need. Now SparkFun is announcing a new department – the Department of Education. SparkFun Electronics always has focused on Sharing Ingenuity – providing extensive online resources as well as offering a variety of in-house workshops and events. The recent development of a new Department of Education within SparkFun emphasizes the company’s passion and commitment to providing individuals with the tools they need to explore the world of embedded electronics. For more information about Spark- Contact: Fun’s new Depart- SparkFun Electronics ment of Education, 6175 Longbow Dve, Suite 200, Boulder, CO 80301 contacteducation<at> Tel: 0011 1 1 303 284 0979 sparkfun.com Website: www.sparkfun.com siliconchip.com.au can think of. Retail price is $199 (Cat A2551). It’s available from any Altronics store, reseller or the phone/mail order/online store. Contact: Altronic Distributors Pty Ltd PO Box 8350, Perth Busn Centre, WA 6849 Tel: 1300 780 999 Fax: 1300 790 999 Website: www.altronics.com.au Pocket-size decontamination wipes off toxic dangers to workers Enware is introducing to Australasia a toxic chemical Decontamination Mitt, so effective that versions of it are used by armed forces to neutralise deadly Chemical Warfare Agents. The Decon Mitt consists of a pouch containing wipe-down mitt impregnated with decontaminating powder called FAST-ACT. A soft pad material is backed on the mitt by a film, to protect the user from any contamination by substances to which it is applied. FAST-ACT as used in Decon Mitts is a non-toxic, non-corrosive and environmentally friendly sorbent that provides better chemical protection Contact: and decontamination Enware Australia Pty Ltd capabilities than cur- 9 Endeavour Rd, Caringbah NSW 2229 rently available indus- Tel: (02) 9525 9511 Fax: (02) 9525 95367 Website: www.enware.com.au trial technologies. WES’ new range of CB radio gear WES Components have released a PDF showing an extensive range of UHF and 27MHz CB radio antennas, mounts, bases, brackets and other goodies. To have a look at their range, call in to the WES Showroom (see right) or log onto Contact: http://wesnews. WES Components wescomponents. 138 Liverpool Rd, Ashfield NSW 2131 c o m / w e s n e w s / Tel: (02) 9798 9233 Fax: (02) 9798 0017 Website: www.wagner.net.au WN204UHF.pdf June 2011  89 Vintage Radio By Kevin Poulter An insight into the manufacture of quality valve radios in the USA nearly 100 years ago Radio Manufacturing in 1925: the Wells Gardner story This month we take a look at high quality radio manufacturing during the 1920s in the USA. This was on a much larger scale than in Australia but the methods were largely the same, with similar machinery and tools. I n the 1920s, radio manufacturing proliferated. Yet from the thousands of companies that then existed, few images of production were ever taken or remain. It was considered a breach of security for an employee to photograph inside a factory so some factories eventually closed without a single photograph taken. Fortunately the US company Wells Gardner produced some images, most likely for salesmen to show stores that they were a big operation and not just a suburban garage or tiny factory. This provides us with wonderful insight into 90  Silicon Chip the manufacturing techniques of the late 1920s. In 1925 production started at Wells Gardner with a discussion between the Manager, Sales Manager and Design, regarding the best radios to meet market trends. In the mid to late 20s, the only choices were a console radio, a “coffin” bread-box style, or a mantel in a wooden cabinet – and how many valves to have in the design. As was common practice, a number of brands were used, with many consoles and huge table sets sold under the M. Wards’ “Airline” name. This strongly influenced the selling price and most manusiliconchip.com.au facturers had economy and top-end models. It appears that Wells Gardner mainly supplied the top end of the market, as many of their radios were nine-valve. When the design was completed and approved, parts were ordered in and kept in the secure store. Staff had no access, as many liked to build their own hobby radios or knew people that did and may otherwise have ‘lifted’ some parts. Not having enough of some parts to complete a production run was even worse than the pilfering, as production, distribution and sales were all then delayed. siliconchip.com.au A major part of the production at that time was huge stacks of fine timber and the best craftsmen to fabricate it into beautiful cabinets. The ‘engine room’ generated all of the electric power required by the factory and offices, due to the generally unreliable reticulated power at the time. Many components were made in-house, though most likely not valves nor capacitors, as they were more specialised. Transformers and coils were definitely made in the plant, as they often were in Australian factories of the era. Here women wind and assemble coils. June 2011  91 included in looms or used singularly for direct links between components. The following photographs show the construction of a nine-valve receiver. All the radios were assembled using the factory jig, with handles to enable easy roll-over of the chassis. Transformers made in the factory were tested in a jig, with seven meters plus an auxiliary meter. The jig’s contacts match the pins on the transformer, and the lever in the centre applied a little pressure to ensure all contacts were sound. So the test was essentially automated - place the transformer upside down on the jig, push on the lever and switch on. Looms were made in factory, to connect most of the components together electrically. A loom jig was a piece of wood with the loom plan drawn on paper and attached. Conventional building nails in the wood guided every bend and other nails indicated the end of each wire’s course. When all the components were made or purchased in, a production run commenced. Each section had a supervisor (you can just see his hat in this photograph) to ensure the people worked hard and to a good standard. Toilet breaks were generally not permitted. He was also expected to ensure the continuous supply of parts to the line. In the foreground, wires are being cut to length, stripped on their ends and pre-tinned with solder. Some would have heat-resistant sleeving added. Prepared wires were 92  Silicon Chip When a wire was run though to its destination, it was terminated by winding once around the end nail and then cut off. On completion, the entire loom was hand-stitched together and/or bound with cloth strip. Eighty years later, this exact method is still used to make custom looms for vehicle restoration. The male in the centre of the above picture is the supervisor, with his desk in the foreground. siliconchip.com.au The Gallery: some of Wells Gardner’s radio masterpieces 92-1929 WG-82 WG-161 Wells-1933 A 1933 console radio 1933 Airline Superhet and a closeup of the dial Five valve chassis WG-30-126-2 These chassis were photographed in a studio, printed to a large size, air-brushed and retouched, then the retouched image photographed again, resulting in the final negative and print. Today we use Photoshop, saving an immense amount of time and cost. Eight-valve WG-30-106-3 showing top side and underchassis The connection loom between the two chassis appears to be covered by winding a fabric strip over, an early version of the tape used in later looms. siliconchip.com.au June 2011  93 About these photos: restoration from glass negatives by Kevin Poulter* Production was not easy for the staff. Conditions were high-pressure and the area poorly lit. Note the 4-gang variable condensers and the age of the women – from teens to seniors. The caged area in the rear is most likely a lockable store. The final assembly was mainly done by men, with the woman on the far right probably a long-term employee with advanced experience. A supervisor stands on the far right and in the foreground there’s a row of disassembled jigs, below the desk. The images in this feature were ‘rescued’ from an American owner and were reproduced from the original glass-plate negatives. The images were top quality, as the photographers almost certainly shot them in a view (bellows) camera. It’s likely they had at least one incandescent spot-lamp, however shutter speeds still needed to be down to about one second or even longer. The result was at least one of these images showed double-imaging. The sheer size of the glass negatives – four inches x five inches – overcame the low quality of the lenses. These intrepid photographers had to load, carry and process glass plates! Some even coated their own plates (negatives). Recently I used Photoshop to restore them to better-thanoriginal. This included lightening the areas where the main photographic light was much dimmer in the distance, due to the inverse square law (the phenomena where doubling the distance reduces illumination to approximately one quarter). Other than the restoration mentioned, the images are identical to the day they were photographed. As recently as the 1950s to 1970s, radio and television factory employees in Australia still worked in conditions similar to those shown here, seated in long rows, with the women doing the most repetitive work and men doing more advanced functions, like design, cabinet crafting and final testing. * Kevin Poulter is a professional photographer based in Melbourne. You can see more of Kevin’s work at www.imageaustralia.info On completion, the radios were packed in wooden boxes, then when ready for shipping, were loaded into a rail car at the company’s own rail siding. SC The final test bench has custom-built test equipment, Burgess “B” batteries, plus wet cells near the floor and spare valves if needed. The photograph is so clear, some boxes of RCA UX-280 valves can be seen at the top and a row of valves in the centre. There’s a screwdriver, radio pliers, soldering iron and an open end spanner on hand too. 94  Silicon Chip siliconchip.com.au SILICON SILIC CHIP Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 PO BOX 139, COLLAROY NSW 2097 email: silicon<at>siliconchip.com.au Phone (02) 9939 3295 Fax (02) 9939 2648 siliconchip.com.au YOUR DETAILS This form may be photocopied without infringing copyright. 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PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES IN AUSTRALIAN DOLLARS AND INCLUDE GST WHERE APPLICABLE. MAIL OR This form to PO Box 139, June 2011  95 Collaroy NSW 2097 03/11 WANT TO SAVE 10%? S C (PRINT EDITION) AUTOMATICALLY QUALIFY FOR REFERENCE $ave SUBSCRIBERS* CHIP BOOKSHOP 10% A 10% DISCOUNT ON ALL BOOK PURCHASES! SILICON ILICON HIP (*Does not apply to website orders) SELF ON AUDIO by Douglas Self 2nd Edition 2006 $69.00 PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00 See Review A great aid when wrestling with applications for the PICAXE series of microcontrollers, at beginner, intermediate and advanced April 2011 levels. Every electronics class, school and library should have a copy, 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. 474 pages in paperback. along with anyone who works with PICAXEs. 300 pages in paperback SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $88.00 PIC IN PRACTICE 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. 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. AUDIO POWER AMPLIFIER DESIGN HANDBOOK PIC MICROCONTROLLER – your personal introduc- by Douglas Self – 5th Edition 2009 $81.00 tory course By John Morton 3rd edition 2005. $60.00 "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. 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. PRACTICAL GUIDE TO SATELLITE TV OP AMPS FOR EVERYONE By Garry Cratt – Latest (7th) Edition 2008 $49.00 By Carter & Mancini – 3RD EDITION $100.00 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. Substantially updates coverage for low-speed and high-speed applications, and provides step-by-step walk-throughs for design and selection of op amps. Huge 648 pages! PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00 NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 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. 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. USING UBUNTU LINUX RF CIRCUIT DESIGN by J Rolfe & A Edney – published 2007 $27.00 by Chris Bowick, Second Edition, 2008. $63.00 Ubuntu Linux is a free and easy-to-use operating system, a viable alternative to Windows and Mac OS. Introduces Ubuntu, tells how to set it up, covers the various Open Office applications and gives troubleshooting hints and tips. Highly recommended. 222 pages in paperback DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00 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. 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 See Review Feb 2004 by Ian Hickman. 4th edition 2006 $61.00 A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. ELECTRIC MOTORS AND DRIVES PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se By Austin Hughes - Third edition 2006 $51.00 Intended for non-specialist users of electric motors and drives, filling the gap between academic texts and general "handbooks". Explores all of the widely-used modern types of motor and drive including conventional & brushless DC, induction motors, steppers, servos, synchronous and reluctance. 384 pages, soft cover. e Review Feb An essential reference for engineers and anyone who wishes 2003 to design or use variable speed drives for induction motors. by Malcolm Barnes. 1st Ed, Feb 2003. $73.00 286 pages in soft cover. BUILD YOUR OWN ELECTRIC MOTORCYCLE AC MACHINES by Carl Vogel. Published 2009. $40.00 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, single-phase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; OR FAX (24/7) OR NZ – $12.00 PER BOOK; PAYPAL (24/7) REST OF WORLD $18.00 PER BOOK PHONE – (9-5, Mon-Fri) eMAIL (24/7) OR To Call (02) 9939 3295 with Your order and card details to Use your PayPal account silicon<at>siliconchip.com.au Place 96  S ilicon C hip with order & credit card details (02) 9939 2648 with all details silicon<at>siliconchip.com.au with order & credit card details Your Or use the handy order form on P105 of this issue Order: 1-13 See Review March 2010 OR MAIL Your order to PO Box 139 siliconchip.com.au Collaroy NSW 2097 *ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST WANT TO SAVE 10%? S C (PRINT EDITION) AUTOMATICALLY QUALIFY FOR REFERENCE $ave SUBSCRIBERS* CHIP BOOKSHOP 10% A 10% DISCOUNT ON ALL BOOK PURCHASES! SILICON ILICON HIP (*Does not apply to website orders) SELF ON AUDIO PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00 by Douglas Self 2nd Edition 2006 $69.00 See 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. 474 pages in paperback. Review A great aid when wrestling with applications for the PICAXE series of microcontrollers, at beginner, intermediate and advanced April 2011 levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback SMALL SIGNAL AUDIO DESIGN PIC IN PRACTICE By Douglas Self – First Edition 2010 $88.00 by D W Smith. 2nd Edition - published 2006 $60.00 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. 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 introduc- AUDIO POWER AMPLIFIER DESIGN HANDBOOK tory course By John Morton 3rd edition 2005. $60.00 by Douglas Self – 5th Edition 2009 $81.00 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. "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. OP AMPS FOR EVERYONE PRACTICAL GUIDE TO SATELLITE TV By Carter & Mancini – 3RD EDITION $100.00 Substantially updates coverage for low-speed and high-speed applications, and provides step-by-step walk-throughs for design and selection of op amps. Huge 648 pages! 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. PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00 NEWNES GUIDE TO TV & VIDEO TECHNOLOGY 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 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. USING UBUNTU LINUX by J Rolfe & A Edney – published 2007 $27.00 RF CIRCUIT DESIGN Ubuntu Linux is a free and easy-to-use operating system, a viable alternative to Windows and Mac OS. Introduces Ubuntu, tells how to set it up, covers the various Open Office applications and gives troubleshooting hints and tips. Highly recommended. 222 pages in paperback DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00 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 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. See Review Feb 2004 PRACTICAL RF HANDBOOK by Ian Hickman. 4th edition 2006 $61.00 A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. ELECTRIC MOTORS AND DRIVES By Austin Hughes - Third edition 2006 $51.00 PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se Intended for non-specialist users of electric motors and drives, filling the gap between academic texts and general "handbooks". Explores all of the widely-used modern types of motor and drive including conventional & brushless DC, induction motors, steppers, servos, synchronous and reluctance. 384 pages, soft cover. e Review Feb An essential reference for engineers and anyone who wishes 2003 to design or use variable speed drives for induction motors. by Malcolm Barnes. 1st Ed, Feb 2003. $73.00 286 pages in soft cover. AC MACHINES BUILD YOUR OWN ELECTRIC MOTORCYCLE 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. by Carl Vogel. Published 2009. $40.00 Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; eMAIL (24/7) To silicon<at>siliconchip.com.au Place siliconchip.com.au with order & credit card details Your Order: 1-13 See Review March 2010 OR FAX (24/7) Your order and card details to (02) 9939 2648 with all details OR NZ – $12.00 PER BOOK; PAYPAL (24/7) Use your PayPal account silicon<at>siliconchip.com.au OR REST OF WORLD $18.00 PER BOOK PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details OR MAIL Your order to PO Box 139 June 2011  97 Collaroy NSW 2097 Or use the handy order form on P85 of this issue *ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST 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 silicon<at>siliconchip.com.au How accurate is GPS speed measurement? I have noticed that in the work car, to drive at 110km/h by the GPS unit (a well-known brand) I need to drive at close to 125km/h by the vehicle’s speedometer. While I realise that the car speedometer is probably reading high, I am aware that the GPS unit approximates the Earth’s surface and therefore potentially also is in error. Using the other traffic as a guide, I expect that the GPS unit is reading fairly accurately but given the expense should I get it wrong, I was wondering how much of an error will the GPS unit produce – is it close enough that the “grace factor” applied by the speed camera units cover the potential error of the unit? (T. M., Paradise, SA). • This topic of large vehicle speedometer error has been discussed in the past and is a consequence of the Australian Design Rules which specify that the speedo must be optimistic (ie, give a high reading) while the odo­meter is supposed to be highly accurate. Your experience is typical. While there is bound to be a small GPS speed measurement error you can expect it to be less than 1%. By comparison, vehicle speedos are typically 8-9% high in their readings at speeds of 100km/h or more. Be warned though, vehicle speedometers are usually fairly accurate between 40km/h and 70km/h. So don’t go above the speedo indication in areas with these speed limits otherwise you risk being booked. self-discharge from taking the battery below 11.5V which will cause it to fail. In other circumstances, with larger batteries, float charging is recommended (see the answer below). Is there any point in float charging? Seldom-used batteries need float charging I have a number of devices that use 12V SLA batteries in charge/discharge service, some of them only occasionally. When fully charged, the charge drops back to a trickle, about 10mA. I notice that if I disconnect the charger completely for days or even weeks, on reconnection it charges for about 20 seconds before dropping back to float. So it would appear that I am only wasting power (about 15W in total) by leaving these things on continuously. So is there any benefit in leaving them on permanent float? Despite spending a lot of time trawling the net, I have been unable to find a satisfactory answer to this. (G. H., Mt Martha, Vic). • SLA battery manufacturers recommend a float voltage between 13.5V and 13.8V to maintain charge and to provide maximum battery life. If you have a battery-operated device which is normally off then there is probably not a lot of point in leaving it on float charge. However, you will need to charge it from time to time to prevent A friend in Melbourne recently asked my opinion as to whether SLA batteries should be constantly float charged. I said “yes”. The slightly higher voltage on the float charge prevents the formation of a permanent lead-sulphate layer on the lead electrodes. Once a sulphate layer has formed, it creates a barrier between the positive and negative plates, resulting in a higher internal resistance and decreased capacity of the cell. If this lead-sulphate becomes permanent due to a lack of recharging, it becomes an inert substance in the charge and discharge process. His concern was that, to float charge two SLA batteries (one in a golf caddy and the other in an electric bicycle), the chargers continually used 12W. In winter, the batteries stood unused for many months, which seemed to be a lot of wasted power. I thought that without float charging, the battery capacity would shrink a lot faster. I suggested that a more ef- Preamplifier For A Flexible Piezo Film Sensor I’d like to use the Pre-Champ (SILICON CHIP, July 1994) to amplify the signal from a flexible piezo film sensor – see http://www. meas-spec.com/product/t_product. aspx?id=2478# However, what would I need to do to match the Pre-Champ to such a high-impedance load – possibly two, either in series or in parallel? I’m not too sure at this stage if it would be worse for bass response. Is there a frequency response chart available for the Pre-Champ pream98  Silicon Chip plifier? (P. S., Lane Cove, NSW). • The data sheet indicates that the recommended load impedance is 10MΩ, which you would need to get maximum bass response from the sensor. With this in mind, the Pre-Champ is never going to the job. Besides which, its -3dB bass roll-off is at 72Hz – not good enough, in all probability. Instead, we suggest that use the single-transistor preamplifier circuit featured in Circuit Notebook in June 2002. This could be lashed up on the PreChamp PCB and does provide a load impedance of 10MΩ. Note that the potential output of the sensor could range up to several hundred volts and this could be a real problem with the suggested preamplifier (or any other preamplifier, for that matter). If you are proposing to use it on a musical instrument, the signals might not be that strong. You might need to check the likely signal amplitude with a scope, using a 10MΩ probe. siliconchip.com.au Using LEDs With The Digital Lighting Controller Would it be possible to include a low voltage output option for the Digital Lighting Controller (SILICON CHIP, October - December 2010) slave unit so that strings of LED lights could be connected directly? This would then take the place of the multifunction controllers that lights in the shops use, especially when they fail after a year. (L. B., Auckland, NZ). • If your LEDs run off AC (some do) then the Digital Lighting Controller can drive them directly with some minor modifications. Essentially, this just involves changing the mains connectors (both input and output) to something suitable for hooking up low-voltage AC. The slave module is slightly less efficient switching low voltage AC but it should work. For DC-powered LED strings, it certainly is possible to build a Mosfet-based slave module (alternaficient (switchmode?) battery charger might help. However, after some further thought I came up with another idea. He could use his chargers, which could be switched on and off using a time switch, with a duty cycle of perhaps on for one hour in 24 hours. This might be sufficient to reverse the sulphate layer before it became permanent (the battery manufacturers would have data on this). His electricity usage would certainly be lower. Is there a better way? (A. F., Chinderah, NSW). • You are correct in recommending float charging in these applications. Leaving batteries to self-discharge over a period of many months, particularly in winter, is a big mistake as these batteries can be very expensive to replace. It is even more important when applied to batteries in boats. These can be left for long periods and if they are not kept on float charge, they will be dead when you next need to use them. And we can vouch for the fact that boat batteries are very expensive, as is the cost of installation. Heavy batteries in awkward confined boat engine rooms can add up to lots of dosh. In this particular case though, the original charger may start up in fast charge mode each time the timer powsiliconchip.com.au tively, Darlington transistors could be used). Ideally, this would contain an adjustable current sink for each channel although many LED strings run directly off 12V, which would simplify the design. The same logic IC arrangement could be used as in the AC slave, with the Darlington array and following components changed over. In either case, the same master module can be used with a line in the configuration file to indicate which slave(s) are controlling DC loads. This is not strictly necessary but improves brightness control because with a DC load, brightness is proportional to duty cycle but with an AC load, it actually varies with the area under a sine curve. By default the master module compensates for this; the added line in the configuration file disables that compensation for better brightness linearity. ered it up. This may cause the battery to be initially boosted to the cut-off voltage before switching to absorption (if this is incorporated) and then to float. This could be worse for the battery as it would effectively be cycled between the two voltages. This would need to be checked. A switchmode float charger might be best to use once the batteries have been charged by the main charger. The switchmode float charger could be cycled on and off with a timer. Explanation of open-collector outputs I have a comparator powered from a 15V rail. One of its inputs is fed with a 10V reference and other with the voltage it is comparing. I would like its output to go into my microcontroller. Now the comparator (LM311) has an open collector output which means it’ll need a pull-up resistor. But what I am unsure of is what do I pull it up to? Can it be 5V? Then it will be at the right level to interface to the micro or will it have to go through a zener diode to get down to the 5V level? Or does it have to be pulled up to its own supply? My second question is this: I wish to get a 5V supply for a microcontroller ANTRIM TRANSFORMERS manufactured in Australia by Harbuch Electronics Pty Ltd harbuch<at>optusnet.com.au Toroidal – Conventional Transformers Power – Audio – Valve – ‘Specials’ Medical – Isolated – Stepup/down Encased Power Supplies Encased Power Supply www.harbuch.com.au Harbuch Electronics Pty Ltd 9/40 Leighton Pl, HORNSBY 2077 Ph (02) 9476 5854 Fax (02) 9476 3231 and a couple of LEDs from either a AA or AAA battery using some sort of step-up regulator. Could you suggest any that come in an 8-pin package and are reasonably simple to work with? (B. W., via email). • The LM311 comparator output is “open collector”. This means that the collector of the output transistor is not connected internally. It requires an external resistor to a positive supply rail so that the output will be low when the transistor is switched on and it will be pulled high via the resistor when the transistor is off. The open-collector feature means that the output can be pulled higher or lower to different supply rail from that feeding the LM311 comparator itself. For example, the comparator might be run from a 15V DC rail and the open-collector might be pulled via the resistor to a 5V supply. This could be useful in driving TTL circuitry or CMOS circuitry running from +5V. In your case, the pull-up resistor could be 10kΩ, for example. A step-up supply running from one or two AA or AAA cells can be made using a TL499A. This was used in the June 2011  99 Latch-Up Problem In Ultra-LD Stereo Amplifier Preamp A year or two ago I built the UltraLD 2 x 100W Stereo Amplifier. Its sound quality is superb but it has had one irritating problem ever since its completion that I can’t solve. Normally at switch-on, the bargraph LEDs flash momentarily and all is well. However, quite often they don’t and when that happens, the bargraphs don’t work when a signal is applied and the output is distorted as well. The only cure is to switch the amplifier off and on again. However, it may take two or three attempts before the amplifier “boots up” properly. Investigation shows that, when it is not working properly, there is no positive voltage from the 7815 voltage regulator, even though the input voltage is there. The negative supply from the 7915 is OK. I have replaced the 7815 voltage regulator and all components fed by it including the two TL072 bargraph buffers, the two 5534 preamp ICs, and the electrolytic capacitor between the output of the regulator and earth. I didn’t replace the other electros that straddle the positive and Water Tank Level Meter in the November 2007 issue and the 3-9V DC-DC Converter in March 2004. Alternatively, the MC34063A could be used and this was the basis of the August 1992 step-up converter design. LM2917 frequency-tovoltage converter I have built the frequency-to voltage converter featured in the Circuit Notebook pages of the June 2010 issue. This was designed to allow air-flow sensors which have a variable frequency output to be used with your Voltage Interceptor published in “Performance Electronics for Cars” (a SILICON CHIP publication). I am having trouble getting an output voltage close to 4V at the maximum frequency range of 100Hz to 150Hz. When the 10kΩ resistor is connected to the output and pins 5 & 10 bridged, the result is about 250mV. Readings without the 10kΩ resistor are a static 2.3V and only vary by about 2mV with adjustment of trimpot VR1. 100  Silicon Chip negative regulator outputs because they seem to be OK. The problem, however, persists and I’m getting to the “wit’s end” department. I wondered if, at switch-on, the regulator might be seeing the discharged electros as a short-circuit and cutting out but why does this only happen sometimes and why is the negative side not affected? Please can you shed any light on this perplexing problem? (J. P., via email). • Interestingly, we would not have had a definitive answer for this problem up until a few months ago and we would have simply advised you to check for defective components or bad soldering. However, in developing the Universal Voltage Regulator board that was presented in the March 2011 issue, we discovered that there is a serious problem when you have a pair of 7815/7915 or other 7800/7900 series regulators fed by positive and negative half-wave rectifiers. That is the exact situation in the preamp board of the Ultra-LD 100W Stereo Amplifier. What happens is that, depending on whether the positive or negative I also note that there is no variance in voltage on pin 2 with adjustments to the input frequency. Pin 2 shows 900mV static at all input frequencies and pin 3 only has 2mV (also static). All input voltages to pins 8, 9 & 11 match those in the article. Any help would be very much appreciated. (F. E., via email). • The LM2917 is available in many variants. The circuit shown in the June 2010 issue is for the LM2917N. Other LM2917s have different pin outs and you will need to check this before connecting up a circuit. As published, the circuit is set for a nominal 40-400Hz range. For your narrow frequency range, the output will vary from 4V at 150Hz to 2.7V at 100Hz. The 10kΩ resistor is required between pins 5 & 10 to ground as the output is an emitter follower and the resistor provides the load. The circuit will not work if the input signal does not swing over and below a 0.55V range. For more sensitivity use a lower value resistor instead of the 1kΩ value at pin 11. rail comes up first, the regulator which turns on first will pull the complementary regulator’s output up (or down) to the point where it latches up and prevents normal operation from occurring. In your case, the 7915 is turning on first and in charging its associated 100µF capacitor and the two 10µF capacitors across the two output rails, it actually pulls the output of the 7815 below 0V. The poor old 7815 interprets this as an overload condition and latches up. So you have to turn the unit on and off maybe several times to get the correct power-up condition. As far as we can determine, this fault condition only occurs with certain brands of regulator which is why we didn’t see it when we were developing the Ultra-LD 2 x 100W Stereo Amplifier back in 2001. The solution is to connect reversebiased diodes across each regulator’s output. You can see how we did this in the Universal Regulator circuit, in Fig.4 on page 40 of the March 2011 issue. The diodes in question are D5 and D6. Pin 2 switches charge to the capacitor at pin 3 and measuring the voltage at pin 2 does not indicate much about what is happening. Using the Tempmaster to control an incubator I would like to use my Tempmaster Mk2 to control a 300W heater in my poultry egg incubator. The required temperature is 37°C. Is it possible to adjust the resistor values in the “temperature set” circuit to extend the range of the Tempmaster to cover this temperature? (S. A., Echunga, SA ). • Yes, it is quite easy to adjust the resistor values in the temperature set part of the Tempmaster Mk2 circuit, to allow it to maintain a temperature of 37°C. In fact, there is only one resistor value that needs to be changed: the resistor from TP1 to the +5V line (pin 3 of REG1). If you change this resistor’s value from 2.7kΩ to 2.2kΩ, this will give VR1 an adjustment range from 3.00V to 3.166V, corresponding to temperatures siliconchip.com.au from 27°C to 43.6°C. The temperature will be set to your desired value of 37°C when VR1 is then adjusted to give a DC voltage of 3.10V at TP1. Charge controller for power-tool batteries Have you any articles on building a charger controller for power tool nicads? I have tried unsuccessfully with the temperature measurement method but am interested in a final voltage sensor/switch off. • We did publish a Power Tool Charging Controller in the December 2006 issue and there was a companion article was in the same issue entitled “Bringing A Dead Cordless Drill Back To Life”. This controller uses the rate of change in temperature at full charge (dT/dt). It also has over-temperature cut-out and a back-up timer is included. NiMH and nicad cells cannot be checked for full charge by measuring their terminal voltage. This voltage is dependent on many factors, including temperature, charge rate, cell chemistry and the size of the cell. Instead, end of charge can be detected by the change (fall) in voltage at full charge or via the rapid rise in temperature. In practice, the change in voltage can be small and is difficult to detect reliably. Car battery tester wanted Would you consider a project for a car battery tester with a load that can be varied according to the battery capacity? (D. M., via email). • Have you seen our Battery Condition Checker from the August 2009 issue? This should do the job for you. It uses Mosfets to briefly drag current pulses from the battery and it measures the battery output impedance. The current pulse amplitude can be set to suit the size of the battery. Minivox voice-operated relay is latched on I purchased a Minivox Voice-Activated Relay kit (SILICON CHIP, September 1994) from Jaycar in Melbourne. When connecting it to a 12VDC power source the LED and relay activate without the action of the electret microphone. The relay and LED remain on. I have checked the connections siliconchip.com.au Substitute Wanted For A Cassette Recorder I tape our church service each Sunday so that “shut-ins” can hear the service during the week. The 120-minute tapes I use are becoming hard to get. I use just one side per service to save changing it over and perhaps missing something. Unfortunately, a 60-minute cassette is often not enough. Could I use a DVD recorder instead and burn a DVD each week? If so, I assume I would have much more than 60 minutes of recording time available? Some time ago, I tried using a VCR but must have done something wrong as I got nothing. If I did use a DVD, I would also have to buy a portable DVD player as many old folk may not have a means to play it. (B. P., via email). • Unfortunately there is no simple replacement for the cassette recorder. Generally the best solution is to record so that a CD can be made instead. This involves recording to a memory and then transferring to the CD. and polarity according to the diagram and markings of the circuit board and all is correct. When reading some past letters on this kit there appears to be some confusion about the correct diodes and their positioning/polarity orientation, etc. Is there a problem like this with the kit I have purchased? If not, what could the problem be? (I. G., via email). • There was some confusion over the diodes in the Minivox project article. In particular, diode D1 should be orientated so that its anode is connected to the negative supply. Diode D3 on the PCB should be diode D4 and D4 should be D3. The orientation of D4 should be with the anode to the collector of Q1. The cathode (K) end of the diode has a stripe. However, these problems would have been fixed in the Jaycar kit instructions. If in doubt, contact kits<at> jaycar.com.au Check the pin 7 output of IC1b. This normally should be at about 0V. If it is above 3V or so, then there must be voltage at pin 5 that is above the voltage at pin 6. Pin 6 should be about 2V. If Pin 7 is at about 0V, transistor Q1 CD recorders are available but are not as simple to operate as a cassette recorder. You can record to memory using a computer or specialised digital recorder. One such device is the Gemini iKEY recorder that records in high-quality to a USB flash memory drive. Other recorders include the many MP3 players that have a record function. A CD is the best medium to provide because most people will have a CD player, including the older people who find it difficult to get out of the home. Many would still have a cassette player but it may not be working due to the drive belts that perish. A DVD recorder might work but we are not sure if a DVD recorder will record just audio when there is no video signal present although that could easily be provided using a video test generator. We may look at the possibility of producing a high-quality recorder based on an SD card. could have a short between emitter and collector or there is a short on the PCB. Any voltage at pin 5 would mean that there is noise picked up by the microphone and signal is present at pin 1 of IC1. Or the 100nF capacitor at pin 1 is a short circuit or there is a short on the PCB. Varying the gain of the PreChamp preamplifier I built the 2-transistor PreChamp Preamplifier (SILICON CHIP, July 1994) to run electrets for a CB radio and it’s a ripper. I want to know if it’s possible to put a variable pot somewhere to reduce the gain as sometimes it’s very sensitive? I have tried a few points on the board but have not been successful. If it is possible, what value pot should I use and where does it go? (J. P., via email). • The 100Ω resistor at the emitter of Q1 can be increased to reduce the gain. And ideally, the 22µF capacitor should also be reduced in proportion to the increase in resistance. For example, if the 100Ω resistor is changed to 470Ω, the 22µF capaciJune 2011  101 Next month in SILICON CHIP: July 2011 Ultra-LD Mk.3 Amplifier Module: This is a major update of the Ultra-LD audio amplifier module presented in the August & September 2008 issues and incredibly, has even lower distortion. The new design provides a VBE multiplier transistor to easily set the quiescent current and address the shortcomings of the internal tracking diodes in the ThermalTrak power transistors. As well, it now incorporates 2-pole high-frequency compensation and some other small modifications to greatly improve THD. Lightning Radio Warning Indicator Designed around an TA7642 AM radio chip, this simple circuit will give an audio warning of lightning strikes from approaching thunderstorms – could be a life saver for trekkers, boaties and campers. UHF Rudder Indicator A boon for anyone with a twin motor cruiser, this UHF linked indicator will constantly tell you how the rudders are set. This is essential when doing low-speed manoeuvres such as docking and picking up a mooring when all steering is done with motor control. Note: these features are in the process of preparation for publication and barring unforeseen circumstances, will be in the issue. ON-SALE: Wednesday, 29th June 2011 tor would be reduced to 4.7µF. The capacitor change maintains the lowfrequency rolloff at about 72Hz. PICProbe modes are settable I built up one of the PICProbes as described in the October 2007 issue of your magazine from a kit supplied from Jaycar. It seems to work but it’s doing something a little odd – the red LED is constantly on until it is connected to a logic zero output. Probing a “state zero” will result in the green LED lighting and a pulse from the orange LED. Pushing the button results in the orange LED latching. Is this correct operation as per the original design or is something wrong? (P. M., Wollongong, NSW). • For the red LED to be on unless the probe is connected to 0V indicates that the probe is in the mode where a pull- up is enabled. This pull-up resistor can be disabled by holding the pushbutton in during power up. The probe should then have a floating input and the LED state is not defined until the input connects to a logic high (red LED on) or logic low with the green LED on. If the orange LED stays on (with a press of the pushbutton), then the probe is probably set for the latching mode. This can be disabled by holding the button in for two seconds. Large digital display could provoke road rage Here is a project idea: a large alphanumeric static display you put in the back window of your car. In my case it would display three words sequentially when a button was pushed: “BACK OFF FOOL”. Maybe it could have several messages selectable on a console. I would Notes & Errata Digital Lighting Controller, October 2010: in the Master Unit circuit (pages 40-41), the connections for pins 4 & 5 of IC1 are reversed. The PCB pattern is correct. The Microchip PIC32 (March 2011): on page 21, line 2 of the program listing is incorrect, it should read: #pragma config FNOSC=FRCPLL, FPLLIDIV=DIV_2, FPLLMUL=MUL_20, FPLLODIV=DIV_4 certainly make one. (J. D., via email). • You can already buy large moving marquee displays to perform that function. Mind you, with all the road rage these days, it might not be a good idea SC to provoke some people. 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 Competition & Consumer Act 2010 or as subsequently amended and to any governmental regulations which are applicable. 102  Silicon Chip siliconchip.com.au MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP ELNEC IC PROGRAMMERS High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP C O N T R O L S Tough times demand innovative solutions! IMAGECRAFT C COMPILERS ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 GRANTRONICS PTY LTD www.grantronics.com.au Yes, it’s true! Don’t let its tiny size fool you. This powerhouse receiver covers the AM, FM, LW and entire SW bands from 35 to to30MHz 3.5 30MHz– –andandhashasgenuine genuinedigital Digitalsignal Signalprocessing! Processing! Exclusive to Avcomm, the Tecsun PL-310 DSP normally sells for $90.00 (plus p&h) but if you say you saw it in SILICON CHIP, Avcomm will give you an amazing10% off! CLEVERSCOPE USB OSCILLOSCOPES 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 WOW! A QUALITY DSP HF COMMUNICATIONS RECEIVER FOR 10% OFF? Hurry - stocks are limited. Call Avcomm now - (02) 9939 4377 Made in Australia, used by OEMs world-wide splat-sc.com Modules 537Kits, and Boxes Innovative & affordable projects for hobby, school & industry Shop on-line at: www.kitstop.com.au electronics-the fun starts here For more details visit www.avcomm.com.au Battery Packs & Chargers 3”,5” 7”,9” 10” Super Bright Displays Siomar Battery Engineering FOR SALE PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 8005 6732. sesame<at>sesame.com.au www.sesame.com.au LEDs! Nichia, Cree and other brand name LEDs at excellent prices. LED drivers, including ultra-reliable linear driver options. Many other interesting and hard-to-find electronic items! www.ledsales.com.au questronix.com.au – audiovisual experts solve home, corporate security and devotional installation & editing woes. QuestAV CYP, Kramer TVone (02) 4343 1970 or sales<at>questronix. com.au 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 WANTED CUSTOMERS WANTED: Truscotts Electronic World – large range of semiconductors and passive components for industry, hobbyist and amateur projects CLASSIFIED ADVERISING RATES Advertising rates for these pages: Classified ads: $29.50 (incl. GST) for up to 20 words plus 85 cents for each additional word. Display ads: $54.50 (incl. GST) per column centimetre (max. 10cm). 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We pride ourselves on technical expertise from our staff. Do you think that the following statements describe you? Please put a tick in the boxes that do:  Knowledge of core electronics, particularly at a component level  Retail experience, highly regarded  Assemble projects or kits yourself for your car, computer, audio etc  Have energy, enthusiasm and a personality that enjoys helping people  Opportunities for future advancement and development  Why not do something you love and get paid for it? Please email us your applicaton & CV in PDF format, including location preference. We offer a competitive salary, sales incentive and have a generous staff purchase policy. Applications should be emailed to jobs <at> jaycar.com.au Jaycar Electronics is an Equal Opportunity Employer & actively promotes staff from within the organisation. Advertising Index Altronics.............................loose insert Amateur Scientist CDs................... 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IFC,49-56,104 Keith Rippon.................................. 103 Kitstop............................................ 103 LED Sales...................................... 103 Microchip Technology......................... 7 Ocean Controls................................ 10 Quest Electronics........................... 103 CIRCUIT IDEAS WANTED DOWNLOAD OUR CATALOG at We pay up to $100 for contributions to Circuit Notebook or you could win a piece of test gear. send your circuit idea to: Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. www.iinet.net.au/~worcom RCS Radio..................................... 103 WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au RF Modules................................... 104 Satcam Pty Ltd................................ 11 Sesame Electronics....................... 103 Silicon Chip Binders....................... 104 Issues Getting Dog-Eared? 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