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SILICON 100nF 100nF 16 Vdd 11 Ya3 14 CHIP 15 Ya2 13 Za 13 14 Ya1 26 12 Ya0 25 IC2 74HC4052 20 5 Yb1 6 IC1: 74HCU04 10k 27 3 Zb 3 1 Yb0 S1 E S0 Vee Vss 7 8 2 100 10 8 7 INC GST 33pF ERROR AUDIO $ 95* NZ $ 11 008 INC GST RXIN FSOUT PRINT POST APPROVED X1 - PP255003/01272 24.576MHz IC1e 14 12 FMT1 FMT0 FSOUT 1 9 100nF C1f PSCK0 SEPTEMBER 2009 4 Yb3 2 Yb2 Vd PSCK1 XTO XTI DG 33pF 10 11 7 +5V +5V 100 +5V K 7 D14 .3 Vcc A T +3.3V 19 18 +5V 6 6 5 5 3 3 4 4 12 12 100nF 1M 22k IC5: 74HC14 47k D11 1nF 22k 22k 22k K 10 13 LED5 A 8 8  1 1 2 2 A 14 14 13 13 Using a K K IC5f 12 9 12 D12 K 22k 1 1 F K 3 7 9 9 11 11 PD7 PB0 PB6 PD6 2x 330 PD5 PB7 4 5 Try out 6 PD3 PD4 OLEDS 2 3 4 in your carINPUT & CONTROL BOARD -ANALOG CONVERTER PD0 PD1 PD2 Build a sim 3x 2.2k GND ple OLED ’s cope8! PEBBLE: siliconchip.com.au A fun new graphics program to help lay out protoboards . . . and it’s IC ATMEGA 2 10 IC5b PB1 7 Wideband 02 sensor 7 11 1 F IC5a PB3 for outstanding DVD Sound 6 22k D13 A  13 10 A LED4 14 IC5c +5V 1 F 15 14 5 A PB4 High Quality Stereo DAC 17 22 F PB5 FREE! September 2009  1 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au Contents Vol.22, No.9; September 2009 SILICON CHIP www.siliconchip.com.au Features 35 Introducing OLED Displays Organic LED technology is now affordable for the hobbyist. Here’s a look at some available OLED screens and modules plus a circuit to make a simple oscilloscope – by Mauro Grassi 40 Review: At Last . . . An Affordable Logic Analyser The Saleae Logic costs just $US149 and has eight channels that can record millions of samples at up to 24MHz – by Geoff Graham High-Quality Stereo Digital-ToAnalog Converter – Page 12. 64 Pebble: PICAXE Electronic Bread Board Layout Emulator Free software allows you to produce a professional-looking diagram that shows how a circuit was laid out on a breadboard – by Wayne Geary Pro jects To Build 12 High-Quality Stereo Digital-To-Analog Converter, Pt.1 Build this high-quality Stereo DAC for superb hum-free sound from your DVD player. It accepts both optical (TOSLINK) and coaxial inputs and has left & right audio outputs for connection to your hifi system – by Nicholas Vinen 26 Using A Wideband O2 Sensor In Your Car, Pt.1 Want to accurately measure air-fuel ratios over a wide range? This “Wideband Controller” mates with a Bosch wideband O2 sensor and our Wideband Display Unit and can be used for precise engine tuning – by John Clarke Using A Wideband O2 Sensor In Your Car – Page 26. 72 Build A Simple Seismograph On A Protoboard Build a seismograph on protoboard using a PICAXE-08M, Pebble it and transfer it to a Kiwi Patch Board – by Stan Swan 75 Autodim Add-On For The 6-Digit GPS Clock It senses the ambient light so that a modified program running in the display unit’s micro can adjust the display LED brightness – by Jim Rowe 82 3-Channel UHF Rolling-Code Remote Control, Pt.2 Second article describes how to complete the construction and get the transmitter and receiver units talking to each other – by John Clarke Build A Simple Seismograph On A Protoboard – Page 72. Special Columns 44 Circuit Notebook (1) FireWire-Sensing Mains Power Switch; (2) A Discrete Op Amp For Audio Use; (3) Temperature-Sensing Battery Charger Cut-Out; (4) 6-Digit PICAXE Timer; (5) Relays Can Do It By Themselves; (6) High-Current Voltage Doubler 57 Serviceman’s Log Why do such things only ever happen to me? – by the Serviceman Building The 3-Channel UHF RollingCode Remote Control – Page 82. 88 Vintage Radio The Kellogg TRF receiver – by Rodney Champness Departments   2   4 62 93 Publisher’s Letter Mailbag Product Showcase Subscriptions siliconchip.com.au 94 97 99 102 Ask Silicon Chip Notes & Errata Order Form Market Centre September 2009  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 Mauro Grassi, B.Sc. (Hons), Ph.D 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 Mike Sheriff, B.Sc, VK2YFK Stan Swan SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490. All material 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: $94.50 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 Low sunspot activity presages solar cooling Years ago, when I was at the helm of Electronics Australia magazine, we used to publish “Ionospheric Predictions” every month for the benefit of amateur radio operators. In essence, these predictions help users of shortwave radio make the best use of the radio spectrum. Whether or not certain bands are going to be “open” for use depends on ionospheric activity which is related to solar flares. Yes, yes, I can imagine that most of you are already nodding off. Which is why EA eventually stopped publishing the ionospheric predictions. But Australia’s Ionospheric Prediction Service (IPS – part of the Bureau of Meteorology) still provides this information (see www.ips.gov.au). So who cares? Well, maybe you should. Because even if you have no interest at all in shortwave communications, you do have a considerable vested interest in whether world communications are at risk. And they always are at risk from solar flares. Now that we are all so inextricably linked together via the internet, mobile phones, satellite comms and so on, the world has a truly enormous investment which is at the mercy of Old Sol. A big solar flare could literally wipe out much of this network. This may be hard to comprehend but the biggest ever observed solar flare, in 1859, shorted out telegraph wires, causing fires in North America and Europe, sent readings of Earth’s magnetic field soaring, and produced northern lights so bright that people could read newspapers by their light. As it happened, apart from telegraph wires, there were no communications services in 1859. Today, such a severe solar flare would do unimaginable damage to electricity grids, as well as most communications services, phones, all radio and TV – you name it. If it happened, you could forget Facebook, online banking and virtually every other activity which involves electronic communication – and it could take quite a while, maybe weeks or months, to restore everything! Is such a scenario likely? We don’t really know but we do know that we are heading into another peak of solar activity, in 2013 – just four years away. Let us hope that all those companies who have large direct investments in communications are doing all they can to “harden” their systems against solar flares. Solar flares can occur at any time and they are closely associated with sun spots – Earth-sized or larger blotches on the sun marking areas of heightened magnetic activity. As a matter of fact, in preparation for writing this editorial, initially on the topic of communications risk, I decided to check the number of visible sunspots (using binoculars and projection onto a white screen). I was astonished to find no sunspots at all! Checking on a number of websites confirmed this – sunspots are currently at a record low. Furthermore, the peak of the next cycle, Solar Cycle 24, in 2013, is predicted to be the lowest since Solar Cycle 16 in 1928 and ninth weakest since the 1750s, when numbered cycles began. All of which means that the probability of a big solar flare any time soon is fairly low and the risk to communications is also low. Good news, you might think but that could be utterly wrong. There is something far more serious to worry about. In fact, there is a strong correlation between sunspot activity and solar output. Old Sol could be heading into a long period of low activity and that could mean pronounced global cooling! Apparently, we have been through this many times before, the most recent being the Little Ice Age which came after the Middle Ages warming period. Two pronounced periods of global cooling have been noted in the Little Ice Age – the Maunder Minimum (1645 - 1715) and the Dalton Minimum (1790 - 1820). Both of these corresponded with long periods of low sunspot activity. Well boys and girls, I don’t know about you but I would much prefer to be anticipating global warming rather than cooling. We are going to be disappointed though. If past history is any guide, global warming is good for humans, with increased food production and economic activity. Global cooling, on the other hand, means increased misery. Polar bears should be OK though. Leo Simpson siliconchip.com.au siliconchip.com.au September 2009  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”. AIS article is a winner Stan Swan has totally blown my mind with that article in the August 2009 issue of SILICON CHIP about AIS! Here before dawn at pitch black Port Stephens (Salamander Bay, actually) I informed my wife gravely, “Hmm... there’s a Danish cargo ship about 10 nautical miles out to the east and the Newcastle tugs are getting up steam” (arrgh me lad, old salt talk . . . y’ can’t get up diesel . . .). “How the blazes do you know?” I rattled on with data about the Dane’s dimensions and speed. It’s got to be Stan’s best article yet. Note to Leo: loved the Brookvale office “vessel” too. But send that man a bonus. Alan Ford, Salamander Bay, NSW. GUI for Autotrax Following your feature article on drawing circuits with Autotrax (SILICON CHIP, May 2009), I thought your readers may be interested in the “GUI” I wrote a few years ago, to make working with Autotrax within Windows XP a bit easier. I have set up a web page for anyone interested to download it, plus the other needed files. Carbon capture is widely applicable It was good to see carbon capture and storage (CCS) discussed in the Publisher’s Letters but emissions reduction is not an either/or case of CCS or gas. CCS is highly applicable to natural gas. In fact, one of the biggest CCS projects in the world, Sleipner in Norway, which stores a million tonnes of CO2 every year, is a gas production project. The Gorgon gas project in WA, which will be Australia’s biggest resource project ever, has CCS as a major component. CCS is highly applicable to gas-fired power plants 4  Silicon Chip It also makes printing easier, allowing you to use your windows printer for the PC boards, via an early demo version of Protel for Windows. The whole thing is downloadable from: www.vk7krj.com Ronald Johnson, Rokeby, Tas. Radios wanted for fire museum I am a volunteer fire fighter at the Wandin CFA. I am writing to you for help to find some old CFA radios for the collection at our fire station. The radios are Pye PF2, Icom IC12 and IC24 with modifications, if possible. Any help would be appreciated. Bill ter Haar, Wandin Fire Brigade, Phone (03) 5964 4021. AM interference should have a community solution In the August 2009 issue, page 97, a letter and response is published under the title “Severe Interference From Local AM Radio Station”. Your response suggests some sound practical steps the writer could take to try to resolve the problem. However, as you note, the advice given will not help the community at large. and is the only technology we have that can make major cuts to fossil fuel-fired power plant CO2 emissions. What’s more, CCS is applicable to any large stationary source of CO2, including the burning of coal, gas or biomass, production of gas, fertiliser, steel and cement. Whether we burn coal, gas or wood, CCS is going to be a crucial part of reducing our CO2 emissions in the future, along with improved efficiency, renewables and switching to lower carbon fuels like gas. There are more details at: www.co2crc.com.au Tony Steeper, Canberra, ACT. The resolution of this kind of problem commences with advice of the problem being given to ACMA in the first instance. ACMA should then undertake the necessary steps to ensure the problem is resolved in accordance with its charter and the governing regulations. It surprises me that you did not identify this obvious official path. The local Federal Member could also be briefed on the issue, as it is after all a community issue. Graeme Dennes, Bunyip, Vic. Comment: you make a good suggestion about contacting ACMA and local politicians. However, unless the ABC can be prevailed upon to change their power level or radiation pattern or to move their transmitter tower, we cannot foresee any easy solution for the community at large. It is a common problem in Australian cities as residential development encroaches upon previously vacant land around AM transmitter towers. DAB+ quality is disappointing I have on loan a Sangean model WFT-1D Hi-Fi Component FM-DAB+ Tuner, hooked up to my own highquality stereo system and have been busy evaluating the audio quality from the DAB+ services being broadcast in Perth WA. DAB+ sounds “sort of OK” if one is not too critical. Critical listening reveals that DAB+ as currently being broadcast sounds quite clean but unfortunately also sounds rather clinical, lacking life, ambience and the natural decay of musical sounds expected from a classical music performance. In addition. I have observed very poor stereo imaging. The original Eureka-147 DAB system, as currently used in many European countries attracted many complaints about lack of quality from listeners, particularly in the UK siliconchip.com.au Publisher’s letter lacked logical argument Normally, I read the Publisher’s Letter first and I am used to it containing a logical argument. However, the logic in the letter for the June 2009 edition is completely absent. It contains the sort of pseudo-scientific rubbish that you normally try to debunk. Are you just checking if we are reading it? The worst piece of pseudo-science was the section using the chemical equation. To simplify this argument without using the equation, you are effectively saying: “Water and CO2 are produced together. Water is good for you so CO2 must also be good for you.” This is false logic. Since asbestos is found in rock and rock is not harmful then asbestos is also not harmful? That conclusion is false. The phrase “carbon pollution” is just a convenient way of referring to all the greenhouse gases which are produced or increased by human activity. Just because we don’t say “carbon dioxide and methane and . . .” doesn’t mean that this phrase cannot be used in conversation and written articles. The change from “geosequestration” to “CCS” is actually a step forward in correctly describing the process. As you point out, a major element of the problem is capturing the gases from the sources such as power stations. Even if we had a perfect geosequestration method, it could not be used today because the capture system has not been invented. A little bit of truth, a long where bit rates of 128kbit/sec were the norm. From personal experience listening to DAB in Denmark and the UK, I fully agree; it is not good enough. The DAB+ system as recently introduced in Australia was hailed by some as being twice as good as the original Eureka-147 DAB system, leading one former Minister for Communications to state that with the better digital broadcast system proposed, we can have many more broadcast services than on the old obsolete DAB system. This looks like exactly what is happening: “Never mind the quality, feel the width”. siliconchip.com.au semi-scientific word and you have once again drawn a false conclusion. I am not an atmospheric scientist. I can’t show you the computer models. I can’t prove that the greenhouse effect is a real threat. I have to trust that the Prime Minister is being advised by these scientists and is not misled by the pseudo-science. I cannot understand why you would print this false argument in your fine magazine. Morgan Sandercock, Singleton, NSW. Comment: you seem to have missed the point entirely. Water vapour is a greenhouse gas produced by the combustion of all fossil fuels yet it is never mentioned in the emotive discussion about “carbon pollution”. If there is more water vapour in the atmosphere there should be more clouds and ultimately, more clouds should lead to global cooling, since they reflect sunlight back into space (while providing a lesser greenhouse effect at night). It could well be that water vapour counteracts much of the greenhouse effect of CO2. As far as we know, the IPCC models do not take into account the effect of increasing cloud cover. The carbon dioxide content of the atmosphere is certainly rising but the evidence for the resultant global warming is weak. Dire forecasts of severe global warming and sea level rises in the next 50 years strain credibility. Those scientists advising the Prime Minister have yet to put a convincing argument. A respected BBC engineer made the statement several years ago, that 256kbits/s was necessary for Eureka-147 to broadcast classical music at acceptable quality. This holds true to this day. To the best of my knowledge, all audio compression systems use the principle of throwing away subtle details which, it is assumed, will not be missed by the listener. Subtle details will probably not be missed on speech and certain types of pop music. Unfortunately, this is not the case with classical and certain other types of music which rely on these subtle details in order to sound September 2009  5 Mailbag: continued Nuclear energy is the answer I normally read the Publisher’s Letter and agree with everything. But the Publisher’s Letter in the June 2009 issue – “Let’s have no more of this carbon pollution non­ sense” – was a shock. As a layman in these matters I can only be guided by scientific reports and the overwhelming evidence seems to be that we are headed in the direction of global warming unless we reduce greenhouse gases (including CO2) over the next few years. You were concerned about “hardcore fanatics” but there have been fanatics about every cause. You seemed to take exception to the term “carbon pollution”. Almost everyone uses this term to mean the production of CO2, not soot (OK, it’s sloppy.) In the air, there is a small amount of CO2 and water vapour. A build-up of water vapour is not a problem but a build-up of CO2 is. That is the heart of the problem which you seem to overlook. To me, nuclear energy is the only viable solution for the world’s power needs in the medium term – say 50 years. It is green and clean. The main problem is the thought about waste. First, there is incredibly little waste when compared with coal. It would be a lot better than putting a huge amount of compressed CO2 in the ground. Second, the (Australian) technology for handling waste is first rate and geologically sound. The main problem with nuclear energy is fear of another Chernobyl or Three Mile Island. But those particular nuclear power station designs are well out of date and they simply don’t design them like that natural and live. DAB+ uses the JointStereo principle in addition to audio compression, so reducing the bit rate will seriously affect stereo imaging. In Perth in July 2009, we currently have 27 DAB+ stations indicated, of which 19 are active. Indicated bit rates 6  Silicon Chip any more. With new designs, there is no possibility of melt-downs. Even if everything went wrong they would just gently cool down. In the short term, Australia has plenty of gas which could be used instead of coal in power stations. This would cut the production of CO2 dramatically. The only problem with this is political – the coal lobby is strong and would object. That is the only reason “geosequestration” is being considered. I was in the oil industry for 12 years and to me, “geosequestration” is nonsense, has not been proved and will not work. Peter Wolstenholme, Pymble, NSW. Comment: it is true that there has been overwhelming evidence of global warming. The problem is that much of it has been quite selective. For example, we keep hearing about the polar ice-caps melting. Well, the Arctic has been melting (and it melted completely in the Middle Ages – the Chinese found the way through). But Antarctic ice has been building at 100,000 sq km/decade for the past 30-odd years. We also hear about sea level changes affecting islands in the Pacific whereas the problem there is not rising sea levels but islands sinking due to volcanic subsidence. Carbon dioxide is increasing but it has been much, much higher in the distant past, before man had any effect. All the climate models used by the IPCC do not take into account any variation in the Sun. Climate change exponents seem to reject any notion that there are variations in the Sun’s output. In short, with our present knowledge of climate and weather, we cannot forecast the weather in a month’s time let alone 50 years into the future. are nine stations at 32kbits/s, two at 48kbits/s, eight at 64kbits/s, one at 56kbits/s, one at 72kbits/s, five at 80kbits/s and only one at 128kbits/s. The only one with reasonable stereo spread is the commercial station at 128kbits/s. ABC Classical runs 80kbits/s and it lacks life, ambience, natural musical decay and stereo spread. The ABC Classical FM signal carrying the same program sounds much better. Audio levels (modulation) from the various stations are all over the place, varying by as much as 12dB. I would seriously suggest that ABC Dig, Jazz and Country be changed to 64kbits/s mono, possibly with audio bandwidth restricted to 10kHz. ABC Classical should be increased to 160kbits/s to improve quality and stereo spread, JJJ should be given 128kbits/s stereo and other ABC Services reduced to 64kbits/s or lower in mono. I fail to understand why SBS programs, mainly speech, are being broadcast as 32kbits/s stereo. All of the commercial stations sound very ordinary. Poul Kirk, South Guildford, WA. Comment: the situation with DAB+ in Sydney is similar, with 38 stations on air in early August. ABC Classic & Jazz are running at 80kbits/s, ABC Extra at 72kbits/s, JJJ at 80kbits/s and other ABC stations at 48kbits/s. SBS stations are 40kbit/s or 32kbit/s. The best commercial station is 2CH at 96kbit/s. DAB+ reception needs to improve I recently got a digital receiver for my car, a unit that Pioneer Electronics sell for $300. Installation was easy: stick the antenna on the glass, plug into the cigarette lighter and plug the unit into the auxiliary input of my radio. As for the reception, well, that’s another thing! At the moment there are so many dead zones around the Melbourne metropolitan area that it’s almost not worth using. Inner city buildings, freeways and concrete walls kill it. The best consistent reception that I got was on the Eastern freeway. I’m looking at mounting an external glass-mount antenna to see if it will improve reception. As for getting out of Melbourne, don’t bother. When reception is four or more bars on the aerial indicator and signal quality is 60% or more, it sounds better than AM radios but in stereo. I don’t know where the transmitting antennas are but I can only hope that siliconchip.com.au SA school zones and electric vehicles As an ex-South Australian, I believe the speed zones around SA schools are far more appropriate than any other school zones in any other state of Australia. When I was attending school some 38 years ago, the speed around school zones was 25km/h but it was at fixed times. As I progressed through the years, I became a “School Crossing Monitor” at a crossing that had flashing 25km/h lights. This was a great learning experience for me and other children in road safety. SA’s current speed zone regulations for schools can only be seen as an improvement to the old regulations. Other states should take notice of what SA has done and adopt the same policy: 40km/h around school zones is still an excessive speed, especially where there are parked cars on the side of the road. What is the cost of a child’s life? 40km/h through a school zone is irresponsible and dangerous. Congratulations to my old home state. In response to the editorial comment on the letter “Feedback On Electric Vehicle Conversion” from John Williams, WA, the university I think you are referring to is the Flinders University of South Australia. During the 1990s, Flinders University had an electric vehicle program and during this period they converted two vehicles. The first was a Mini Moke which was used as a test bed for their technology. The second was a Bedford Van. Both of these vehicles were extremely successful and were nearing the final stage which would have included a production model. Just before the commencement of the last year of the project the SA Government stopped funding for the research and therefore the university was unable to continue. The vehicles were subsequently donated to the Birdwood Motor Museum and were on display to the public for a number of years. David Richardson, Wattle Grove, NSW. ADVANCED BATTERY TESTER MBT-2LA Features Computes State of Charge for lead acid battery types (SLA, AGM, Gel, Flooded) Test battery condition – quickly and easily identifies weak or failing batteries Patented high accuracy Pulse Load test – battery safe, non-invasive Test 2-volt, 4-volt, 6,volt, 8-volt, 12-volt Measures battery performance under load, not just voltage or internal resistance Ideal for battery management & cell matching – reduce costs and increase reliability Description The MBT-LA2 provides a comprehensive means of testing the state of charge and battery condition for 2-volt, 4-volt, 6,volt, 8-volt and 12-volt lead acid battery types (SLA, AGM, Gel, Wet). Lightweight, compact design make it an ideal tool for anyone working with lead acid batteries. The microprocessor-controlled instrument tests popular batteries using a patented, high-accuracy pulse load tests. After a fully automatic test cycle, percentage of remaining battery capacity is indicated on the LED bar display. Test results are easy to understand. An integrated cooling fan dissipates heat from testing, and the circuit is protected against over-voltage. Rugged NBR rubber sleeve protects against impact. Includes 48" removeable test leads with sold copper clamps. The accessory kit (K-MBTLA2) includes a hanging strap & magnet for hands-free operation, and a protective soft case. Requires 4AA batteries (not included). Applications there are more installed around Melbourne and outer areas or the transmission power is increased. For anyone thinking about purchasing a DAB+ receiver within the next six months or so, I’d advise they wait until it improves a lot! Mark Sully, Car Stereo Repairs, Keilor, Vic. Social group for ex-AWA employees Some of your readers, who may have spent part (or all) of their working lives in the electronics industry working for AWA, may be unaware of the existence of a social group where they can catch up with old friends. The Amalgamated Wireless Australasia Veterans Association holds quarterly luncheons, open to any exsiliconchip.com.au  Fire/security  UPS  Medical  Industrial  Lighting  Telecom  Mobility  Inspection  Military  Safety  Service  IT  Access control  Auto/marine/RV  Manufacturing  Utilities For more information, contact SIOMAR BATTERY INDUSTRIES (08) 9302 5444 or mark<at>siomar.com September 2009  7 Mailbag: continued Helping to put you in Control Control Equipment DIN Rail Plastic Enclosures We now have a series of plastic enclosures which can be DIN rail mounted or panel mounted using screws From $25+GST Metal Brackets for DC Gearmotors With these brackets it is easy to mount your 20 and 37mm gearhead DC motors. (2 brackets per bag) From $11.75+GST KTA-264 Bidirectional DC Motor Acuator Drive and control the position of a DC gearhead motor. The motor drives a load and is also coupled to a quadrature encoder, photo-interrupter or potentiometer. The position to move is given by a serial command or by an ON-OFF switch $139+GST Solid State Relay cards We have expanded our range of relay cards with solid state relay cards and telecom relay cards. Available as 2,4 and 8 relay card. DIN Rail mounting also available From $22.90+GST ModbusView TCP Our newest version of ModbusView allows you to simulate master and slave Modbus units communicating using Modbus TCP/IP $59+GST Low Cost Process Controller The N480D series of PID temperature controllers are designed for extreme simplicity in operation with high performance only found in expensive high end controllers $139+GST Contact Ocean Controls Ph: 03 9782 5882 www.oceancontrols.com.au 8  Silicon Chip Rejuvenating lead-acid batteries I have been an avid reader of SILICON CHIP and the magazine’s predecessors since high school. I lived on a shoestring for some years and it was necessary to recycle before it was fashionable. I had an Army Indian motor cycle which used a lead-acid battery which was subjected to severe vibration and other abuse. When it failed I would remove the plates and wash them, emptying all the sediment out of the cells. I would then employees of AWA or its associated companies. Enquiries may be made to awaveterans<at>gmail.com Ross Stell, President AWAVA, Kogarah, NSW. Green power is recommended I was pleased to see the in-depth article on Malcolm Faed’s electric vehicle conversion in the June 2009 issue of SILICON CHIP. Hopefully it will raise the question in everyone’s mind: “if private individuals can build practical electric vehicles in their own backyard, why is it that car makers seem unable to?” But I am responding to the letter by John Vance in the same issue, suggesting that it should become mandatory for electric vehicle owners to install solar panels to offset the energy they use. I and many other electric vehicle owners around the country do indeed have grid-connect solar on our homes, however it is usually done for ethical reasons, not economic. Private grid-connect solar installations are a relatively expensive way to increase Australia’s renewable energy generation capacity, since we miss out on the economies of scale possible with commercial renewable energy generation plants. As end users, there are many ways we can reduce the environmental impact of our electricity usage. This can be done for electric vehicles as well as our homes. The incremental pollution intensity replace them and fill with distilled water, followed by a slow charge. I then replaced the water once more and followed with a further charge, after which I would refill the cells with full strength acid. This gave the battery new life, albeit with reduced capacity. Later I applied it to car batteries and was also successful. This would be aided by the much later development of the Battery Zapper featured in the July 2009 issue. Terry Lealand, ZL2BBO, Hawera, NZ. of the energy drawn from the grid, CO2 or otherwise, varies with time of day and load. The incremental increase in pollution from pulling a kilowatthour from the grid during peak load is greater than it is when the grid is at low load, usually during early morning. This is especially true for West Australians on the SWIS grid, where the bulk of our present wind generation occurs at night. We can also directly influence the origin of our electricity. The best way we can all make a difference is to sign up for Green Power, a federally regulated scheme available throughout Australia which ensures any electricity you use must be accounted for from renewable sources. For more information, you can visit www.greenpower.gov.au I sincerely encourage everyone to sign up for Green Power, regardless of whether or not you have an electric vehicle. Together we can send power companies the right message. As Mahatma Gandhi once said, “you must be the change you wish to see in the world”. Matthew Lacey & Ian Hooper, Aust. Electric Vehicle Association. Comment: readers should be aware that the caps set under the proposed Carbon Pollution Reduction Scheme mean that individuals buying Green Power or taking their own measures to reduce energy use will not be actually reducing Australia’s overall emissions of carbon dioxide. This may be changed but it has yet to happen. siliconchip.com.au CHINA PCB Supplier prototype thru production . 1-layer up to 30-layer . Cost and quality . On time delivery . Dedicated service . Instant Online Quote & Order Fig.1: a typical ...........Day and Night telephone circuit from the 1960s. One piece orders are welcome! C h e ck our low price anline d sain ve the big $days $$ of electromechaniPhone lines have limited current capability cal switching and impulse dialling Regarding your reply to David was of the order of 25-50mA and is Gates’s letter (“School Zone Legis- about the same today. lation In SA Not So Silly”, August In fact, the rotary dial contacts 2009), please be aware that the SA place a dead short circuit across the school speed limit has never been line for about 60ms during each of anything other thanweb: 25km/h since the dialling pulses, as can be seen www.pcbcore.com the speed limits were “metricated”. from the accompanying schematic Prior to that timeemail: it wassales<at>pcbcore.com 15mph of a typical phone from 1963 (Fig.1). (about 24km/h). phone: 86(571)86795686 If the power available had been At no time was it as high as enough to run a train set or a vacuum 40km/h (25mph) in SA. cleaner, the dial contacts would have However, there are in SA a number been destroyed in very short order! of school zones where the 25km/h Regarding the 240ms delay in the limit applies “when children pres­ GPS Clock mentioned in a letter in ent”, at any time, 24 hours a day, the July 2009 issue, this could be every day. This rule causes a lot of “cured” by having the PIC procesconfusion with motorists as they try sor add one second to the time read to work out whether a figure dimly from the GPS receiver, then feeding seen at night might be legally a child this new data to the display drivers or an adult. at the commencement of the next Regarding the letter “Comment time block from the receiver. on Vacuum Cleaner Story” from The only time this would give Peter Mallon in the same issue, I trouble would be when we have feel that someone has been having “leap seconds”, when the clock him on with the story of a train set would display the extra second being run from the phone line. As precisely one second later than it an ex-PMG technician I can state actually occurred. quite positively that the maximum G. Mayman, current available from the phone Dover Gardens, SA. Adapting to SMD technology I read the letter from Alfred Hirzel with interest. I agree with him that SMD technology is not too difficult for hobbyists but I have to disagree with the use of soldering irons. But first, SMD technology has consiliconchip.com.au siderable advantages, as follows: (1) SMD boards can be far quicker to etch (smaller size) and prepare, with far fewer holes. (2) Many components are available far more cheaply in SMD packages than through-hole. (3) Some components are available CHINA PCB Supplier prototype thru production . 1-layer up to 30-layer . Cost and quality . On time delivery . Dedicated service . Instant Online Quote & Order ...........Day and Night One piece orders are welcome! Check our low price and save big $$$ web: www.pcbcore.com email: sales<at>pcbcore.com phone: 86(571)86795686 only in SMD packages. (4) Finished boards are lower in profile, leading to easier mounting. With projects consisting mostly of SMD components we have found that the largest amount of time is spent physically locating components. Once you have them all in front of you, the entire project can have the solder paste applied and reflowed in far less time than a through-hole board, provided you have the right tools. While the largest SMD devices can be hand soldered, it is a process that is close to the limits for hand soldering. As you move to smaller and smaller components the task of hand soldering them becomes exponentially more difficult and, of course, BGA (ball grid array) components are impossible to solder by hand. As a minimum, you need the following: (1) A method of storage of SMD components so that you can locate them (many have no markings). (2) Solder paste dispenser. (3) ESD-safe tweezers. September 2009  9 Mailbag: continued (4) Young eyes or some method of getting a magnified view of the board. (5) A reflow tool. A colleague and I have been developing tools to allow us to reliably produce boards using SMD components. The most important of these is a solder paste dispenser. It is important to be able to dispense the correct amount of solder when using small components, such as 0603 resistors and TSSOP outline ICs. My favourite, from the perspective of cost, ease of use and general utility, is a pneumatic design that is held like a pencil and allows the controlled dispensing of “dots” of solder paste. My colleague’s tool of choice is a positive displacement pump that is about the size and weight of a soldering iron but again, is held like a pencil. In combination with a PICAXE which controls a small stepper motor, this can dispense repeatable 0.1µL (1/10 of a cubic mm) dots of solder paste and with reduced precision, even smaller dots. Our tests (to destruction of components and/or tracks in some cases) illustrate that only extremely small amounts of solder paste are required. One need only look at a modern PC board to notice how little solder is used. By contrast, the typical hobbyist approach to soldering SMDs generally results in the use of far too much solder which dramatically increases the risk of solder bridges. The evidence of this is that most people suggesting these techniques have solder wick as a necessary component in their approach. Neither I nor my colleague have young eyes. My colleague has an overhead video camera connected to a monitor. I use either a modified web cam or a simple magnifier with an integrated lamp. 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Until recently, we have been using a reflow tool for reflowing the solder on assembled boards, a tool available for not much more than the price of a decent temperature-controlled soldering iron. For some time my colleague was (carefully!) using a hot air gun to reflow his boards. Our latest project is a reflow oven and tests (with manual temperature control) have yielded extremely professional looking results at minimal cost – certainly less than the price of my rework tool. The production of SMT boards is another issue but one that I won’t dwell on, as the techniques are not that much different to those used by anyone making their own boards. However, it is worth saying that our current techniques are almost at the level where we can consider using uSMD-14 chips (ie, 14 “pin” BGA chips similar in size to a 1206 resistor). Much of our work is experimental and a driving factor is to make this easily affordable (although, my col- Significant dates relating to broadcasting I would like to draw attention to some errors in the article by Alan Hughes on Digital Radio, Pt.5, in the August 2009 issue, in the table of significant dates. 2MBS-FM started broadcasting Australia’s first licenced stereo FM program in the early hours of 16th January 1975, on 92.1MHz (not in 1976, as in the table). 3MBS started in Melbourne somewhat later. Community broadcasting was running well before the ABC’s official start on Australia Day in 1976. Prior to the 2MBS start of broadcasting, we had demonstrated two stereo FM programs simultaneously, using low power exciters at the “75 Sounds Fantastic” Hi-Fi show at Centrepoint in August 1974 and at the “Australian Hi-Fi” show at the Koala Motel in September 1974. Subsequently, we constructed a 1kW transmitter in 1975 and later in 1977 a 10kW transmitter, the latter operating reliably for some 150,000 hours before being relegated for standby use. Articles about FM appeared in Electronics Australia in May 1975 about 2MBS changing to 102.5MHz and in January 1978 on constructing a tuner to receive FM broadcasts. The Community Sector really showed the way for the widespread adoption of FM throughout Australia. I hope this will correct the minor errors in a valuable article. Max Benyon, Cremorne, NSW. siliconchip.com.au Challenge to electrical licencing restrictions I am a Mechanical Engineer teaching Automation & PLC control at Chisholm Institute and am contracted out to do this at the manufacturing plant at Toyota, Altona. In 2007, I managed to obtain an Electrical Occupier’s Licence. I then enquired about obtaining a full licence. I was advised by ESV Victoria (written document) that if I completed CERT III electrical (using RPL) etc, I could obtain a supervised licence. They have now revoked their documented instructions and I am challenging their decision at league’s hand-made masterpieces of mechanical engineering are certainly not cheap in quantities of one!). We have discovered that most of the “limits” for hobbyist construction fall into three areas: tools, parts availability and conceptual. The tools are now pretty easily available (with some notable exceptions) and component availability is no longer an issue, with many suppliers able to provide parts at extremely good prices. The major factor limiting hobbyists (and we speak from experience) is the leap you need to make from using components that you can pick up between your fingers, to those that require you to use tweezers and magnification. At one stage we thought 1206 was small. The only 1206 component we would now use with any regularity is a 1206 link as it allows several tracks to be run under it. We have recently decided that 0603 components are so easily used that we will use them wherever possible on “real” projects. We are currently sourcing some 0402 components for tests. Many of our techniques have remained static since we thought 0805 resistors were tiny and we marvelled at our test boards using them. Recently, a question we asked ourselves was “will we ever regularly need to use anything larger than 1206?” in the context of the maximum size dot of solder paste to be dispensed. The answer, unsurprisingly, was “No”. You can do it. It is easy. And you’ll siliconchip.com.au VCAT shortly. Amendments to the Electrical rules (2002) means that any licensing decision is challengeable outside their power base. ESV Victoria are throwing up every electrical rule they can think of, ie, dating back to 1946 as one example, so I have stirred up a hornets’ nest. Chisholm Institute of TAFE is supporting me and if I win, this could be a breakthrough for a lot of electrical/electronic engineers, especially since I am a mechanical engineer. Rupert Cranswick, Beaconsfield, Vic. Comment: we hope you succeed, Rupert. never look at a 0.25W resistor the same way again. Steve Hodges, Cloverdale, WA. Help wanted for servant wiring system I bought a house which is heritagelisted and built in 1889. The house has a system for servant’s bells. There is a “bell press” at the front door and in each of four rooms in the house. In the kitchen is an indicator board and bell which are connected by low-voltage wiring to each bell press. The way it is intended to work is this: if someone presses the button at the front door, the bell in the kitchen rings and the indicator board shows that it is the bell at the front door that has been pressed. I need assistance from someone to make the system work. My electrician has installed the low-voltage wiring but beyond that, he is at a loss. He does not have experience with “antique” electrical installations. Both the indicator board and each of the bell presses appear to be in sound condition. There is no obvious damage or deterioration. It just needs someone with the technical skills to bring the system back to life. Is there anyone who can help me? I can be contacted at margr<at>hotmail.com Brian O’Donnell, Brisbane, Qld. Comment: we understood that most households had lost their servants just SC after World War 1. into Video/TV? There’s something to suit every video/TV viewer in the SILICON CHIP reference bookshop Television & Video Technology – by KF Ibrahim A full and comprehensive guide to video and TV technology including HDTV & DVD. $ 70 DVD Players and Drives – by KF Ibrahim DVD technology and applications ideal for engineers, technicians, students, installation and sales staff. $ 95 Practical Guide To Satellite TV – by Garry Cratt The book written by an Aussie for Aussie conditions.Everything you need to know. $ 49 You’ll find many more technical titles in the SILICON CHIP reference bookshop – see elsewhere in this issue September 2009  11 Ver s a t ile de si gn acc ep t s Are you listening to CDs via your DVD player? Does your DVD player have average sound quality or worse, cause buzz and hum problems when hooked up to your hifi system? Either way, you need this high-quality Stereo Digital-To-Analog Converter (DAC) to get first class sound and zero hum. T HIS 24-BIT, 96kHz-capable stereo DAC provides sound quality equal to the best high-end CD players, regardless of price. It has one coaxial S/PDIF input and two TOSLINK (optical) inputs, to which you can connect a DVD player, set-top box, DVR, computer or any other source of linear PCM digital audio. It also has left and right RCA sockets for connection to a stereo amplifier or home theatre receiver. If you already own a DVD player of average quality or better, you can hook it up to this DAC and immediately 12  Silicon Chip upgrade the sound quality. Most DVD players have mediocre audio quality from their audio outputs, especially in terms of distortion (see “DVD Players: How Good Are They For HiFi Audio?” – SILICON CHIP, October 2007). So why are typical DVD players so poor in audio performance? Partly it is because they are designed down to a very low price and while their onboard DAC might be quite a reasonable component, the supporting circuitry has been cut to the bone in order to keep the overall price as low as pos- sible. It is also true that many cheap (and not so cheap) DVD players are plagued with quite strong extraneous RF in the audio outputs, mainly related to the video output signals that they continuously produce, regardless of whether they are playing DVDs or CDs. In addition, virtually all DVD players, except the most expensive models, use switchmode power supplies. These have the advantage of being very efficient and especially with respect to recent models, have very low standby power consumption. The drawback siliconchip.com.au Build a high-quality stereo DAC for superb sound from your DVD player Pt.1: Design by NICHOLAS VINEN bo t h op t ic al & c oa x i a l in p u t s of switchmode power supplies is that they produce lots of switching harmonics which can also get into the audio outputs. Finally, because all DVD players these days are double-insulated and come with 2-core power cords, they inevitably cause hum and buzz when connected to the audio inputs of highfidelity amplifiers which are usually earthed via a 3-core mains cord. There is no simple way to fix any of these problems but this new DAC project fixes them all and provides first-class audio performance to boot. valid signal on one of its three digital inputs and when one is detected, it immediately locks onto it and works. Alternatively, you can select the wanted input signal by pressing the relevant button or you can do it with a Philips RC5-compatible remote control (such as most universal remotes) which can also be used to control the volume from the left and right outputs. As previously stated, the unit accepts both TOSLINK (optical) and coaxial (S/PDIF) inputs, while a pair of RCA sockets are used for the left and right stereo outputs. Main features User interface Our prototype DAC is housed in a one-unit high rack-mount case. The front-panel controls are just an on/ off switch and three LED-illuminated momentary pushbuttons. In operation, the DAC scans for a The user interface provides two functions – display of the DAC status and control over its configuration, primarily selecting between inputs. Status display is provided by the five LEDs on the front panel. The siliconchip.com.au LEDs in the three illuminated buttons show which of the three channels is currently selected. They correspond, left-to-right, to the inputs on the rear panel, with the RCA S/PDIF input being number 3. The two other LEDs indicate whether there is a valid S/PDIF signal detected on that channel (yellow LED) and whether any audio data is present (green LED). The yellow LED also flashes to acknowledge signals from the remote control. Holding down various combinations of the buttons on the front panel allows you to enter a set-up mode where you can assign remote control functions and configure the automatic input switching. The automatic input switching allows the DAC to select whichever inSeptember 2009  13 Specifications Signal-To-Noise Ratio: -108dB (unweighted, 22Hz – 22kHz); -114dB (A-weighed), both with respect to 2V RMS Total Harmonic Distortion: <0.0018% <at> 1kHz and 2V RMS Channel Separation: -105dB <at> 100Hz & 1kHz; -85dB <at>10kHz; -73dB <at> 20kHz Linearity: within 1dB <at> -90dB Frequency Response: +0.0, -0.15dB, 20Hz-20kHz Supported Sample Rates: 28-108kHz Supported bit depths: 16-bit, 20-bit & 24-bit Supported Channel Formats: stereo PCM Clock Jitter: jitter tolerant; clock jitter is typically less than 50 picoseconds put has a valid signal. It allows you to leave the DAC on and switch between various input sources, without the need to manually change channels. For example, if you have a DVD player and set-top box connected, and after watching a DVD you switch the DVD player off and the set-top box on, the DAC will change inputs by itself about 10 seconds after you’ve turned the DVD player off. This delay can be changed depending on your preference. It works as follows. In operation, the DAC constantly monitors the current input status for two parameters: (1) the presence of an S/PDIF signal and (2) the presence of audio data (non-silence). This is the same information which is displayed via the status LEDs. After a user-defined period (default 10 seconds) without a valid signal, the input channels will enter a “scanning” mode where each input is rapidly selected in turn. This scanning continues until a valid signal is detected at which point it stops on that input. There is also a user-defined period of silence (default 1 minute) after which scanning will begin, even with a valid signal present. This is because many devices with digital audio outputs keep their outputs active even when they are not playing any material, eg, when the DVD is stopped. Thus the only reliable way to determine if content is actually being played is to look for an audio signal. Of course, you don’t want it to start scanning the instant there is silence, as there are often short silent periods between tracks, or you may be changing discs or briefly pausing playback. 14  Silicon Chip The two delays can be configured from 100ms up to several hours, or disabled entirely. In addition, it’s possible to configure different delays if the current channel has been manually selected, either from the front panel buttons or the remote control. This is so that you can set the automatic scan times fairly short without having it start scanning too soon after you force it to a particular channel. By default these delays are set to five minutes without a signal and scan on silence after a manual channel change is disabled. Default input & volume control There is also the matter of which input is active when power is first applied. By default the first input is selected but you can configure it so that the default is any of the three inputs, or so that it immediately scans, or even so that it starts up with whichever input last had a valid signal before it was powered off. Finally, there is a built-in volume control in the DAC and it is possible to use the remote control to change the volume. This has a 30dB range but we don’t recommend using it if you want the very best sound quality. Because the volume control is digital, total harmonic distortion will become worse as the volume is reduced. If you do control the volume using a remote, it will remember the last setting the next time it is powered on. The initial default is maximum volume and that’s where it should be left for best sound quality. Note also that multi-channel audio formats like DTS or Dolby Digital are not supported and in any case, many DVD players turn off the TOSLINK (optical) output when multi-channel modes are employed. This means you have two choices when using this DAC with a DVD player in a home-theatre configuration. One option is to connect the DVD player’s outputs directly to your amplifier along with the DAC outputs using a separate set of cables and switch between them, depending on whether you are playing multichannel or stereo content. Alternatively, if you only have stereo speakers, you can configure your DVD player to convert multi-channel content to stereo on the digital output and play all content via the DAC. Some, but not all, DVD players have such a feature which is usually configured via an on-screen menu. If you just want to use a DVD player to play CDs you can ignore the DVD player’s stereo outputs altogether and just use the digital output. It is also possible to use a CD player with digital outputs although they are becoming less common. Because the DAC supports 24-bit 96kHz content as well as CD quality (16-bit, 44.1kHz) and other common audio formats, it is also possible to play higher definition audio content. The supported range of sample rates is 28-108kHz and recognised bit depths are 16, 20 & 24 bits (although in reality 16-bit content is always promoted to 20 bits when sent via S/PDIF). This covers most common linear audio formats. De-emphasis is also supported, although very few CDs are recorded with it enabled. However, de-emphasis has been included since it is part of the CD Audio “Red Book” standard. While the ability to play back 24-bit 96kHz content is attractive, there is a catch: many devices capable of playing back audio of this quality disable their digital outputs when doing so! This likely includes all “DVD Audio” players, which is a great pity. Presumably the music industry was worried about people making digital copies of such content and thus deny us the ability to use the digital output for high-quality content at all. No wonder DVD Audio failed to take off! However, even plain old CDs will sound great played back through this DAC as long as they were properly recorded and mastered. Regarding the audio quality, not only does the DAC chip itself provide high-quality audio output but the S/ PDIF decoder “re-clocks” the audio siliconchip.com.au Fig.1: block diagram of the Stereo Digital-To-Analog Converter. It has two TOSLINK (optical) inputs and one coaxial input and these are fed to an S/PDIF decoder (IC3) via a multiplexer (IC2) and then to a stereo DAC (IC6). The DAC then drives current-to-voltage converter stages IC7, IC8, IC10 & IC11 and finally the differential amplifier output stages (IC9 & IC12). The circuit is controlled by microcontroller IC4 which selects the input signal and accepts inputs from the IR remote control receiver and the pushbutton switches. data to remove “clock jitter”. Clock jitter refers to the fact that the clock frequency of the data being transmitted over the digital link varies somewhat sample to sample. Ideally, there will be no jitter, meaning the clock pulses (and thus data bits) come at exactly the same interval but consumer equipment often doesn’t have the best clock stability and this can prejudice the dynamic range. The decoder solves this by re-clocking the data using a Phase Locked Loop (PLL). The PLL’s frequency is locked to the sample frequency of the data being received but because only the average clock frequency determines the PLL frequency, if the PLL is sufficiently stable it will reject most of the jitter. The DIR9001 decoder from Texas Instruments/Burr Brown claims a typical specification of around 45 picoseconds jitter at 44.1kHz and 30 picoseconds jitter at 96kHz when the master clock is running at 512fs, which is how it is configured. You may be wondering why the decoder IC chosen isn’t capable of handling sample rates up to 192kHz. After all, the DSD1796 DAC supports this sample rate and some content is available at 192kHz, so it would be nice to support it. The main reason is that Burr Brown does not make a 192kHz S/PDIF decoder, and other choices such as the Crystal CS8416 have inferior specifications, including jitter tolerance. For the CS8416, the output jitter is quoted as around 100ps – twice that of the DIR9001. Since most content available is still 44.1kHz or 48kHz, and since the difference in quality between 96kHz and 192kHz audio is minimal, we feel that the DIR9001 is the superior device. PC board line-up Inside the chassis, the circuitry is accommodated on four PC boards: an Input & Control Board, a Front-Panel Switch Board, a Stereo DAC/Analog Board and a Power Supply Board. In the block diagram of Fig.1, the Stereo DAC and all blocks to its right are mounted on the DAC/Analog Board while the circuitry to the left is on the control board. The front panel board carries the buttons, LEDs and an infrared remote control receiver. Not shown on Fig.1 is the power supply board. This is identical to that used in the Studio Series Stereo Preamplifier (see October 2005) and is available from both Jaycar (Cat. KC-5418) and Altronics (Cat. K-5501) as a kit. It can be run from a small 150-15V toroidal transformer or from a 15VAC plugpack. Block diagram Fig.1 shows the main circuit sections. To the left are the two TOSLINK inputs, the S/PDIF input and the infrared remote control receiver. These are fed into multiplexer IC2 and then to the S/PDIF decoder IC3. The output of the decoder in turn feeds the Stereo Issues Getting Dog-Eared? Keep your copies safe with these handy binders. REAL VALUE AT $14.95 PLUS P & P Available Aust, only. Price: $A14.95 plus $10.00 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. siliconchip.com.au September 2009  15 TOSLINK RECEIVER 2 3 100nF 100nF 1 100pF 2 16 Vdd 11 Ya3 15 Ya2 Za 13 14 Ya1 12 Ya0 TOSLINK RECEIVER 1 3 IC2 74HC4052 100nF 4 Yb3 2 Yb2 1 Zb 3 5 Yb1 1 Yb0 100pF 2 6 IC1: 74HCU04 K S/PDIF INPUT CON1 10k D10 100nF A 100 Vee Vss 7 8 9 10 IC1e 14 12 10 11 7 K 300 S0 100nF IC1f 13 S1 E +5V D9 A +5V K 5V DC POWER INPUT +5V 0V 470 F 3  470nF A OUT IN IRD1 D14 1N4004 REG4 LM3940T-3.3 +3.3V +5V GND 22 F 100nF 1 6 6 5 5 3 3 4 4 12 12 100nF 1M 22k IC5: 74HC14 47k 5 D11 1nF 1 F 22k 22k 22k K 10 13 LED5 LED4 S1 S2 A  K S3 A  K LED1 A A  K LED2 K  K 12 A 1 1 2 2 14 14 13 13 22k 1 F D13 8 A  IC5f 10 A 8 6 IC5c +5V A 2 14 D12 K 22k 1 IC5a 2 1 F K 3 IC5b 4 7 2x 330 LED3 7 7 9 9 11 11 FRONT PANEL SWITCH BOARD SC 2009 STEREO DIGITAL-TO-ANALOG CONVERTER INPUT & FRONT PANEL BOARDS Fig.2: the Input Board carries the TOSLINK & S/PDIF inputs, the multiplexer (IC2), the S/PDIF decoder (IC3) and the microcontroller (IC4). The Front Panel Switch Board (yellow background) carries the switches, LEDs and IR receiver. 16  Silicon Chip siliconchip.com.au DIGITAL I/O +3.3V 1 3 100nF 100nF 5 14 13 26 25 20 27 3 2 1 100 7 X1 24.576MHz 33pF 8 24 Vcc Vdd DOUT PSCK0 BCKO FMT1 LRCKO FMT0 CLKST ERROR RST FSOUT1 CKSEL FSOUT0 RSV AUDIO FILT XTO XTI 8 11 6 10 10 9 SCKO IC3 DIR9001 DGnd 6 33pF 12 PSCK1 RXIN 22 F 4 4 5 21 +3.3V 28 19 Q1 BC327 22 BFrame 18 17 EMPH 16 Uout 15 Cout E 47k B C Q2 BC327 680 E B 47k 15 C 14 4.7nF AGnd 23 16 12 47k 68nF 2 +5V 100nF 7 20 Vcc 19 18 17 15 13 14 9 100nF AVcc PB5 PB2 PB4 PC4 PB3 PC5 PB1 PC3 PD7 PC2 PB0 PC1 PC0 PB6 RST 16 27 28 7 26 9 25 11 24 13 23 (TO DAC BOARD) 1 IC1c IC1a 1 12 11 10 PD6 3 IC4 ATMEGA48/V IC1b 2 5 4 9 IC1d IC5d 6 9 8 11 PB7 A 6 2 3 4 3x 2.2k D14: 1N4004 K A LED4 PD3 PD4 PD0 AREF GND GND 100nF K A LM3940T-3.3 BC327 22 B E K LED5 K A 21 PD1 PD2 8 siliconchip.com.au 10 PD5 D9–D13: 1N4148 5 IC5e 8 GND IN C GND OUT September 2009  17 What Are S/PDIF And Toslink? The acronym S/PDIF (or SPDIF) stands for Sony/Philips Digital Interface. Basically, it is a standardised serial interface for transferring digital audio data between consumer-level equipment such as DVD and CD players, DAT and DVD recorders, surround-sound decoders and home-theatre amplifiers. S/PDIF is very similar to the AES3 serial digital interface used in professional recording and broadcasting environments. In operation, each digital audio sample (16-24 bits) is packaged along with status, control and error-checking information into a 32-bit binary word. This is then modulated or encoded into a serial bitstream using the Biphase Mark Code (BMC). BMC involves combining the data bits with a clock signal of twice the data bit rate, in such a way that a binary “1” results in two polarity reversals in one bit period, while a binary “0” results in a single polarity reversal. This double bit-rate signal is selfclocking at the receiving end and has no DC component. The BMC encoded serial bitstream is then transmitted as a 400mV peak-to-peak signal along a single 75-ohm coaxial cable. In most cases, the cable connectors used are standard RCA or “Cinch” connectors, as also used for analog audio and composite video. Although originally developed for conveying linear PCM (LPCM) digital audio signals as used in CD and DAT audio, DAC (IC6) while all three are under the control of the microcontroller (IC4). IC4 also accepts inputs from the ill­uminated pushbutton switches and from the IR remote receiver (after filtering) and it drives the LEDs. The DAC has two sets of differential outputs and these drive four currentto-voltage converter stages involving IC7, IC8, IC10 & IC11. The four balanced voltage outputs from these stages then drive differential op amps IC9 & IC12 to derive the left and right audio outputs, respectively. Circuit details Now let’s have a detailed look at the circuitry of the Input & Control Board – see Fig.2. The two TOSLINK optical receivers each deliver a TTL (5V peak) output signal. The coaxial input is a little more tricky because S/PDIF over coaxial cable (75Ω) is a fairly low level signal – around 0.5V peak-to-peak and even less after cable termination. Therefore the coaxial signal receiver circuit consists of an amplifier which boosts this signal to TTL levels. This part of the circuit is identical to that found in the Two-Way SPDIF/ Toslink Digital Audio Converter (SILICON CHIP, June 2006), with one exception. The 74HC04 IC has been replaced 18  Silicon Chip S/PDIF has also been adapted for conveying compressed digital audio, including Dolby Digital (AC-3), DTS and MPEG-2 audio. TOSLINK is essentially just the S/PDIF signal format converted into the optical domain, for transfer along optical-fibre cables. The accompanying table (see above) shows the most common domestic audio bitstream formats and the S/PDIF/TOSLINK bit rates for each one. Note that LPCM audio is rarely used for DVD-Video, because even a stereo audio track requires a BMC bit rate of 6.1Mb/s. Many current-model DVD players and recorders are provided with either coaxial S/PDIF or TOSLINK digital audio inputs and outputs, or quite often a mixture of both. Similarly, many home-theatre amplifiers are provided with coaxial S/PDIF and/ or TOSLINK inputs. This is also the case with many up-market PC sound cards. with a 74HCU04 (IC1). This has two effects: (1) the current consumption is reduced significantly when there is no signal present on this input and (2) the inverter does not oscillate in this condition. The resulting three TTL S/PDIF signals, one from each input, are then fed into the 74HC4052 analog/digital multiplexer (IC2). Just think of IC2 as a selector switch under the control of the microcontroller (IC4). Depending on which input is selected by the microcontroller, one of them is fed into the DIR9001 Digital Audio Interface Receiver (IC3). This does the S/PDIF decoding. The DIR9001 requires a 3.3V supply which is provided by an LM3940T-3.3 3-terminal regulator (REG4). IC3 employs a 24.576MHz crystal together with two 33pF load capacitors and a 100Ω current-limiting resistor. This provides a frequency reference for the decoder, to determine the actual sampling rate of the audio signal. This is necessary in order to provide the ability to apply digital de-emphasis, since the digital filter response needs to match the sample frequency. The DIR9001 also requires two 5% metal-film capacitors (4.7nF and 68nF) and a 1% metal-film resistor (6.8kΩ) to form the PLL loop filter. The remaining decoder associated components are power supply bypass capacitors. The DIR9001 decoder converts the digital signal into a serial PCM stream (DOUT) which is passed directly to the DAC chip itself, along with three clock signals. These are the sample clock (LRCKO), bit clock (BCKO) and master clock (SCKO). The sample clock matches the audio signal’s sample rate while the bit clock is generally 64 times that rate and is used to clock the actual data. The master clock signal is also a multiple of the sample rate – in this case, 512 times. The master clock is used to time the DAC’s oversampling, which not only makes the post-DAC analog filters easier to design but is also required for a delta-sigma architecture DAC such as used in this circuit. The decoder also outputs a number of flags which are set according to the contents of the S/PDIF stream. These indicate whether there is a valid signal present (AUDIO, ERROR) and whether the audio has been pre-emphasised (EMPH). In addition, FSOUT0 & FS­ OUT1 indicate the detected sample rate. There is one additional connection to the DIR9001 and that is a reset line (RST) from the microcontroller. Acsiliconchip.com.au siliconchip.com.au September 2009  19 7 9 6 4 1 8 10 11 12 13 14 2 13 11 9 7 5 100nF 6 8 3 4 5 10 3 12 IC6 DSD1796 +IoutR –IoutR Iref +IoutL –IoutL VcomR VcomL 23 15 Vcc1 Vcc2R DAC BOARD STEREO DIGITAL-TO-ANALOG CONVERTER 17 18 20 25 26 21 22 100nF AG1 AG2 AG3L AG3R 19 16 27 24 RST MDO MC MDI MS DGnd Vdd SCK PBCK PDATA PLRCK DBCK DSDR DSDL 28 Vcc2L 100nF 10k 47 µF 47 µF 47 µF -15V 2.7nF 820Ω -15V 2.7nF 820Ω -15V 2.7nF 820Ω -15V 2.7nF 820Ω 3 2 3 2 3 2 3 2 4 IC11 7 4 IC10 7 4 IC8 7 4 IC7 7 8 6 +15V 8 6 +15V 100nF 5 6 100nF 8 22pF 5 22pF 100nF 5 6 100nF 8 22pF 5 22pF 200Ω 200Ω 220Ω 27nF 220Ω 200Ω 200Ω 220Ω 27nF 220Ω 3 2 4 IC9 7 8 6 100nF 5 22pF -15V A 3 2 K 1N4004 8.2nF 180Ω 180Ω 8.2nF 4 IC12 7 8 6 100nF 5 22pF GND IN 2.2nF 100Ω OUT 7805 -15V 2.2nF 100Ω +15V IC7–IC12: OPA134 OR NE5534 (SEE TEXT) 8.2nF 180Ω 180Ω 8.2nF +15V GND RIGHT OUTPUT LEFT OUTPUT Fig.3: the DAC Board carries the DAC chip (IC6). This accepts the PCM signals from IC3 and drives current-to-voltage converter stages IC7, IC8, IC10 & IC11. These op amps in turn drive differential amplifiers IC9 & IC12 derive the left and right channel audio outputs, respectively. The op amps are powered by ±15V rails from the power supply while REG5 provides a +5V rail to power the DAC. SC 2009 47 µF 10 µF OUT GND 1 IN 2 -15V A REG5 7805 K 14 100 µF 25V 100 µF 25V 16 15 -15V 0V +15V DIGITAL I/O P3 P2 P1 POWER INPUT D15 1N4004 The front panel is uncluttered and carries just the power switch, the three input selector pushbuttons (with their integral blue LEDs) and the valid signal and audio data indicator LEDs. The hole in the panel immediately to the left of the pushbuttons is for the IR detector (IRD1). The rear panel carries the left & right audio output sockets, the coaxial & TOSLINK input sockets, the fuseholder and the IEC mains connector. cording to the DIR9001 data sheet, an external reset is required each time power is applied. The microcontroller provides this reset signal by monitoring the 3.3V line with its ADC and holding reset low until the supply rises above 2.7V, as specified in the data sheet. Atmel microcontroller Controlling the whole circuit is the Atmel Mega48/V microcontroller (IC4). This is powered by the main +5V rail which comes from the power supply board described later. Note that the switch buttons (S1S3) are not connected directly to the micro but rather via some RC filters and a 74HC14 hex Schmitt trigger inverter (IC5). This is because when a button is pressed, the contacts tend to 20  Silicon Chip “bounce” and switch rapidly on and off for a short period. Each RC filter and its associated diode delays the button press detection long enough to allow the bounce to cease and the Schmitt trigger inverter adds hysteresis to provide a minimum “on” pulse to the microcontroller. De-bouncing can also be performed in software but the hardware method has its advantages and it’s one less task for the microcontroller to perform. Similarly, the IR receiver’s output is fed to microcontroller IC4 via an RC filter and Schmitt trigger IC5c. This is done to filter out any noise generated by other IR sources in the room (apart from the remote), which could cause false triggering in the microcontroller. By filtering the IR receiver’s output, we ensure that only signals with a minimum pulse width are detected. Basically, the Philips RC5 code “ontime” is a minimum of around 889µs (32 pulses at 36kHz), so the filter is designed to reject any shorter IR pulses. Again, this is not strictly necessary but it only requires a few parts and results in more reliable remote control operation. DAC board Fig.3 shows the DAC Board circuit. The DAC chip itself is a Texas Instruments/Burr Brown DSD1796 (IC6) and, as previously stated, has two pairs of differential current outputs rather than voltage outputs. These are current sinks and the current is directly proportional to the sample value after conversion. This allows for higher performance siliconchip.com.au siliconchip.com.au Fig.4: the low-noise linear supply for the Digital-To-Analog Converter is based on common 3-terminal regulators. It provides ±15V rails to power the audio op amps plus a +5V rail to power the Input & Control Board. than would be possible with a voltageoutput DAC of similar design, as the external op amps can run at higher supply voltages (ie, ±15V) and with separate supply bypassing. There are a number of support components around the DSD1796, most of them supply bypass capacitors. In addition, there is a 10kΩ resistor on pin 20 which sets the output level of the DAC, while a 47µF capacitor between pins 21 & 22 and the supply at pin 23 stabilises the DAC’s internal reference voltage. The first analog stage following each of the four outputs from IC6 is a current-to-voltage converter and lowpass filter. Each stage consists of a single op amp (IC7, IC8, IC10 & IC11) plus an 820Ω resistor and 2.7nF capacitor. The low-pass filter is the first September 2009  21 Par t s Lis t Chassis Hardware 1 1U-high custom steel case with screened front & rear panels 1 15V+15V 30VA or 20VA toroidal transformer (Altronics M-4915A; Jaycar MT-2086) 1 SPST 6A 250VAC slimline rocker switch (Jaycar SK-0975; Altronics S-3202) 1 male chassis-mount IEC socket (Jaycar PP-4005, Altronics P-8325) 1 M205 safety fuseholder (Jaycar SZ-2028, Altronics S-5992) 1 M205 250VAC 500mA slow-blow fuse 1 230VAC 3-pin IEC mains power lead 5 5.3mm ID insulated crimp eyelets (Jaycar PT-4614) 4 M4 x 10mm machine screws 8 M4 nuts 8 M4 shakeproof washers 5 4.8mm fully-insulated female spade crimp connectors 20 small Nylon cable ties 1 40mm-length of 16mm-ID heatshrink tubing (to cover fuseholder) 1 30mm-length of 20mm-ID heatshrink tubing (to cover mains switch) Wire & Cable 1 400mm-length heavy-duty red hook-up wire 1 240mm-length heavy-duty green hook-up wire 1 320mm-length heavy-duty black hook-up wire 1 350mm-length 7.5A 250VAC brown wire for mains cabling of three, the total effect of which rolls off the frequency response at 18dB/ octave above about 24kHz. In operation, the left channel differential outputs from the DAC (IC6), are converted from current to voltage using op amps IC7 & IC8. Their outputs are in turn fed to a passive filter which consists of 220Ω resistors and a common 27nF capacitor. The filtered differential outputs are then combined by op amp IC9 which acts as a differential amplifier and active low-pass filter. Op amps IC10, IC11 & IC12 function 22  Silicon Chip 1 500mm-length 7.5A 250VAC green/yellow wire for mains cabling Input Board 1 PC board, code 01109091, 113 x 93mm 2 PC-mount TOSLINK (optical) receivers (Jaycar ZL-3003, Altronics Z-1602) 1 black PC-mount RCA socket 1 14-pin PC-mount IDC header socket 1 16-pin PC-mount IDC header socket 1 14-pin IDC line socket 1 16-pin IDC line socket 1 3-pin header & shorting jumper 1 500mm-length 16-way IDC ribbon cable 1 2-way screw terminal block, 5.08mm pitch 2 14-pin DIP machined IC sockets 1 16-pin DIP machined IC socket 1 28-pin DIP machined IC socket 5 M3 x 10mm tapped spacers 10 M3 x 6mm machine screws 1 500mm-length 0.71mm tinned copper wire (for links) 1 24.576MHz crystal (HC/49 or HC/49US) (Rockby Electronics) Semiconductors 1 74HCU04 hex inverter (IC1) – do not use 74HC04 1 74HC4052 analog/digital multiplexer (IC2) 1 DIR9001PW Digital Audio Interface Receiver (IC3) 1 ATMEGA48V or ATMEGA48P microcontroller programmed with 0110909A.hex (IC4) in exactly the same manner to produce the right channel audio output. Output op amps Virtually all of the circuit for the DAC Board circuit is as suggested in the Texas Instruments’ data sheet for the DSD1796. However, we did make some important changes. First, after extensive testing, we decided that OPA134 op amps are the best available for this circuit, rather than the NE5534s specified by TI. These are from the same op amp family as the OPA2134 dual op amps 1 74HC14 hex Schmitt trigger inverter (IC5) 1 LM3940T-3.3 LDO 3-terminal regulator (REG4) 2 BC327 PNP transistors (Q1,Q2) 5 1N4148 diodes (D9-D13) 1 1N4004 diode (D14) Capacitors 1 470µF 6.3V electrolytic 2 22µF 6.3V electrolytic 3 1µF 6.3V electrolytic 1 470nF MKT metallised polyester 11 100nF MKT metallised polyester 1 68nF MKT metallised polyester 1 4.7nF MKT metallised polyester 1 1nF MKT metallised polyester 2 33pF ceramic 2 100pF ceramic Resistors (0.25W, 1%) 1 1MΩ 1 680Ω 4 47kΩ 2 330Ω 6 22kΩ 1 300Ω 1 10kΩ 2 100Ω 3 2.2kΩ DAC Board 1 PC board, code 01109092, 94 x 110mm 1 red PC-mount RCA socket 1 white PC-mount RCA socket 1 16-pin PC-mount IDC header socket 1 16-pin IDC line socket 1 3-way screw terminal block, 5.08mm pitch 4 M3 x 10mm tapped spacers 8 M3 x 6mm machine screws 1 500mm-length 0.71mm tinned copper wire (for links) used in the Studio Series Preamplifier, referred to earlier. Alternatively, you can use NE5534s if you wish although these will give a slight increase in harmonic distortion – from around 0.0018% or better to 0.0025% at 1kHz. In view of this, we feel that the OPA134s are worth the extra cost. Note that six 22pF compensation capacitors are shown on the DAC circuit but these are only necessary if you use NE5534s. They may be omitted if you are using OPA134s. However, if you install them anyway, OPA134s can siliconchip.com.au 6 8-pin DIP machined IC sockets Semiconductors 1 DSD1796 24-bit audio DAC (IC6) 6 OPA134 op amps (IC7-IC12) (or use NE5534 op amps for slightly reduced performance) 1 7805 +5V regulator (REG5) 1 1N4004 diode (D15) 1 100nF MKT metallised polyester capacitor Capacitors 2 100µF 25V electrolytic 4 47µF 16V electrolytic 1 10µF 6.3V electrolytic 9 100nF MKT metallised polyester 2 27nF MKT metallised polyester 4 8.2nF MKT metallised polyester 4 2.7nF MKT metallised polyester 2 2.2nF MKT metallised polyester 6 22pF ceramic Power Supply Board Resistors (0.25W, 1%) 1 10kΩ 4 200Ω 4 820Ω 4 180Ω 4 220Ω 2 100Ω Front Panel Switch Board 1 PC board, code 01109093, 103 x 34mm 3 vertical PC-mount momentary pushbutton switches with blue LEDs (S1-S3) (Jaycar SP-0622 or Altronics S-1173) 1 14-pin PC-mount IDC header socket 1 14-pin IDC line socket 4 M3 x 6mm tapped Nylon spacers 4 M3 x 15mm black-anodised pan-head machine screws 4 M3 star washers 4 M3 nuts 1 100mm-length 0.71mm tinned copper wire (for links) still be used, as pin 5 of the OPA134 package is not internally connected. Our second departure from the recommended Texas Instruments’ DSD1796 circuit was to use a single 100nF bypass capacitor across the supply pins (7 & 4) of each amp. This avoids coupling supply noise into the signal ground and also provides effectively twice as much capacitance. Third, we added a fourth low-pass (passive) filter stage to the outputs of op amps IC9 & IC12. This consists of a 2.2nF capacitor following the 100Ω current-limiting resistors and provides siliconchip.com.au Semiconductors 1 infrared receiver module (IRD1) (Jaycar ZD-1952; Altronics Z-1611) 1 5mm yellow LED (LED4) 1 5mm green LED (LED5) 1 PC board, code 01109052, 54.6 x 80mm 1 Micro-U 19°C/W TO-220 heatsink (Altronics H-0637) 2 3-way terminal blocks, 5.08mm pitch (CON1, CON2) 1 2-way terminal block, 5.08mm pitch (CON3) 4 6mm untapped Nylon spacers 5 M3 x 6mm pan head screws 1 M3 nut & flat washer Semiconductors 1 LM317T adjustable positive regulator (REG1) 1 LM337T adjustable negative regulator (REG2) 1 7805 +5V regulator (REG3) 8 1N4004 diodes (D1-D8) Capacitors 2 2200µF 25V PC electrolytic 2 100µF 16V PC electrolytic 1 47µF 25V PC electrolytic 3 10µF 16V PC electrolytic 2 100nF 50V MKT metallised polyester Resistors (0.25W, 1%) 2 1.1kΩ 2 100Ω 1 330Ω 5W 5% 1 100Ω 5W 5% a rolloff (pole) at roughly 800kHz. This will slightly attenuate any highfrequency switching artefacts present on the output of the DAC. In addition, since this is a passive filter, it will be effective at filtering any very highfrequency noise which some of the active filter stages may pass through. Power supply As noted, this design uses the lownoise power supply from the Studio Series Preamplifier (SILICON CHIP, October 2005). It provides regulated ±15V and +5V outputs. The power supply board accepts a 30VAC centre-tapped input from the specified toroidal transformer, formed by joining the two 15VAC secondary windings. D1-D4 and two 2200µF capacitors rectify and filter the input to give ±21V DC (nominal) rails. LM317 and LM337 adjustable reg­ ulators (REG1 & REG2) generate the complementary positive and negative supply rails. Their outputs are programmed to ±15V by the 100Ω and 1.1kΩ resistors connected to their OUT and ADJ terminals. We’ve used adjustable regulators because the ADJ terminals can be bypassed to ground to improve ripple rejection, which we’ve done using 10µF capacitors. Diodes D5 & D7 provide a discharge path for the capacitors should an output be accidentally shorted to ground. Two reverse-connected diodes, D6 & D8, across the outputs prevent their respective rails from being driven to the opposite polarity (eg, if a regulator fails), something that should never occur during normal operation. A 7805 regulator (REG3) is used to generate the +5V rail. The 100Ω resistor in line with REG3 reduces power dissipation in the regulator. As the +5V supply draws power from only the positive side of the unregulated DC input, a 330Ω resistor across the negative input is included to balance the rails so that they decay at similar rates at power off. The +5V rail provides the power to the circuitry on the main Control Board as well as driving the LM3940T-3.3 regulator which provides power for the DIR9001 decoder. This regulator also provides a +3.3V rail (Vdd) for the DAC. It might seem strange to use a 7805 for REG3 when we want a low-noise supply but in fact this series of regulators have quite low output noise when used with a decent-sized output capacitor. Finally, the +5V rail for the analog section of the DAC does not come from REG3 on the power supply board. Instead, we use another LM7805 5V regulator on the DAC board and this is powered from the +15V rail from the power supply. This is so that digital switching noise in the 5V digital supply does not affect the DAC’s performance. Next month, we’ll show you how to assemble the four PC boards and SC mount them in the case. September 2009  23 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au Using a wideband O2 sensor in your car, Pt.1 For accurate measurement of air/fuel ratios This Wideband Controller is intended to be used with a Bosch Wideband LSU4.2 oxygen sensor and our Wideband Sensor Display to accurately measure air/fuel ratios over a wide range from rich to lean. It can be used for precise engine tuning and can be a permanent installation in the car or a temporary Main Features connection to the tailpipe of the exhaust. • • • • • • • • • • Accurate lambda measurements Pre-calibrated sensor S-curve output S-curve response rate adjustment Heat indicator LED Data indicator LED Engine started detection option Correct sensor heat-up rate implemented Heater over-current and undercurrent shutdown Optional fast heat-up if correct conditions are met 26  Silicon Chip By JOHN CLARKE F OR PRECISE ENGINE tuning and mod­ification an accurate air/fuel ratio meter is a “must have”. An engine that runs rich will use excessive fuel and cause air pollution while an engine that runs too lean may be damaged. Unfortunately, trying to diagnose engine mixture problems with the standard narrowband oxygen sensor fitted to all cars is quite difficult. While it is good enough to indicate the stoichiometric mixture for use by the ECU, it is only accurate over a very narrow band; that it why it is called a narrowband sensor. Typically, most engines should run with a stoichiometric mixture except when accelerating where the mixture may go richer. Alternatively, during cruise conditions and engine overrun, the mixtures might go lean. In contrast, siliconchip.com.au some engines run at stoichiometric continuously, regardless of engine load. So why do you need a controller for a wideband oxygen sensor? In brief, it’s because a wideband sensor is very different from a narrowband sensor. In its most basic form, a narrowband sensor has only one wire and this is the sensor output. There is another connection via the metal frame of the unit. Other narrowband sensors have an internal heater and these units may have three or four wires. Fig.1 shows a cross-section of a typical narrowband sensor. By contrast, a wideband sensor has six wires. This is because it comprises a narrowband oxygen sensor, a heater and an oxygen ion pump which diffuses oxygen ions into or out of the chamber which is monitored by the narrowband sensor. Fig.2 shows the basic set-up for a wideband oxygen sensor installation. At left is the wideband sensor with its six leads which are all connected to the wideband controller module. The controller module then has two outputs. First, there is an S-curve output which simulates the output of a narrowband sensor and can be used by the car’s ECU to control fuel delivery to the engine. Second, there is a linear 0-5V output which drives the Wideband Display Unit (as published in the November 2008 issue of SILICON CHIP). S-curve characteristic The S-curve characteristic is shown in the graph of Fig.3 while the linear 0-5V output is shown in Fig.4. A voltage of 0V indicates a rich mixture (lambda 0.7) while 5V indicates a lean mixture (lambda 1.84). Lambda values for other voltages are calculated using the equation: Lambda = V x 0.228 + 0.7 Note that a multimeter could be used to measure the wideband output voltage instead of the Wideband Display unit. However, most readers will want the combined bargraph and digital display of the latter. Note also that the lambda value is simply the ratio of the air/fuel ratio compared to the stoichiometric air/ fuel ratio. For petrol, it is generally accepted that the stoichiometric air/ fuel ratio (the mass of air required to completely burn a unit mass of fuel) is 14.7:1 but this can drop to 13.8:1 when 10% ethanol is added. siliconchip.com.au Fig.1: what’s inside a narrowband zirconia oxygen sensor. It consists of a zirconia ceramic sensor element with thin platinum electrodes on both sides. A lambda of 0.7 for petrol is the same as an air/fuel ratio of 0.7 x 14.7 or 10.29:1. Similarly, a lambda of 1.84 is an air/fuel ratio of 27.05:1. The stoichiometric air/fuel ratio is typically 15.5:1 for LPG and 14.5:1 for diesel. These values can differ depending on the actual fuel composition and for diesel it varies between the winter and summer fuels. In fact, lambda is probably the best measure of air/fuel mixtures since it is a universal value and not dependent on the specific fuel. Before we describe how a wideband sensor and its associated controller work it is best to become familiar with the operation and characteristics of the narrowband sensor. If you are not sure how narrowband oxygen sensors work we had a full description of this topic in the November 2008 issue of SILICON CHIP. As noted above, wideband sensor design is based on the narrowband Zirconia oxygen sensor but it includes a clever method to obtain a more linear response. This involves a second chamber incorporating a pump cell where exhaust gas enters via the diffusion gap. The oxygen measurement is made within this diffusion gap. The pump cell moves oxygen ions into or out of the diffusion gap in order to maintain a stoichiometric measurement for the sensor cell. If the measured mixture is lean, then the sensor cell detects excess oxygen. The pump cell then drives oxygen ions out of the diffusion gap until the Fig.2: here’s how the Wideband Controller is used with a wideband oxygen sensor and with the Wideband Display described in November 2008 to provide accurate air/fuel mixture monitoring. As shown, the Wideband Controller has both a wideband output and a narrowband (S-curve) output. September 2009  27 Fig.3: the S-curve output from the Wideband Controller simulates a narrowband sensor output (the response follows the Bosch LSM11 narrowband sensor curve). Note the steep slope in the curve at stoichiometric (ie, lambda = 1). sensor cell measures a stoichiometric mixture. Conversely, if the mixture is rich, oxygen ions are pumped from the surrounding exhaust gas into the diffusion gap until the sensor cell reaches its stoichiometric measurement. As a result, the current applied to the pump cell can be either positive or negative, depending on whether oxygen is pumped into or out of the diffusion gap. At this point, it may seem as though the oxygen pump Fig.4: the wideband output from the Wideband Con­ troller is linear with respect to lambda values from 0.7-1.84. The resulting signal is ideally displayed on the SILICON CHIP Wideband Display Unit from the November 2008 issue. actually tricks the narrowband sensor into “thinking” that the mixture is stoichiometric. This might seem to defeat the purpose of having the narrowband sensor at all but bear with us; all will be revealed. Wideband controller Fig.5 shows the basic scheme for a wideband controller. Vs is the output voltage from the oxygen sensor cell while Ip is the current into or out of the pump cell. At the stoichiometric Fig.5: the basic scheme for a wideband oxygen sensor and its associated controller circuit. 28  Silicon Chip point, Vs is 450mV and this is compared against a 450mV reference. If Vs is higher than the 450mV reference, the mixture is detected as “rich” and the Vs sense comparator output goes high. This “informs” the controller that Ip needs to change, to pump oxygen ions into the diffusion gap in order to regain a stoichiometric measurement. Similarly, if Vs is lower than the 450mV reference, the exhaust mixture is detected as “lean” and the comparator output goes low. As a result, the controller adjusts Ip to pump oxygen out of the diffusion gap. Note that if there is no Ip control, the sensor cell behaves like a standard narrowband sensor with an output voltage above 450mV for rich mixtures and below 450mV for lean mixtures. However, with current control, the pump current is adjusted to maintain a 450mV reading from the sensor cell. Variations in the sensor cell voltage indicate the change in mixture in either the rich or lean direction, while the Ip current shows whether the mixture is actually rich or lean. A negative Ip current indicates a rich mixture and positive current a lean mixture. The amount of current indicates the lambda value. Fig.6 plots oxygen content against pump current Ip for lean mixtures. siliconchip.com.au Note that the graph is almost linear. The controller converts Ip current to an equivalent lambda value for display on the Wideband Display Unit. Ip is sensed by measuring the voltage across the 62Ω 1% resistor (in parallel with Rcal). However, during the manufacture of each sensor, the actual resistor used by Bosch is 61.9Ω (a 0.1% tolerance value from the E96 range). Rcal is trimmed so that the voltage across this resistor, measured against lambda, is the same for each sensor. In fact, Rcal can vary from 30Ω to 300Ω, depending on the characteristics of the individual sensor. Hence, the value for Ip shown on the vertical axis of Fig.6 (and Fig.9 which we will come to later) is not the total pump current. Ip in these graphs only relates to the voltage across the 62Ω resistor. So while Fig.6 shows Ip varying between zero and about 2.55mA, the actual range could vary from 0mA to 3.07mA if Rcal is 300Ω or up to about 7.8mA if Rcal is 30Ω. This is really only of academic interest but we mention it for the sake of completeness. The same convention is used by Bosch in its application literature on the LSU4.2 wideband oxygen sensor. Oxygen Concentration 0.0% 3.0% 6.0% 8.29% 12.0% 20.9% Measured Ip 0.00mA 0.34mA 0.68mA 0.95mA 1.40mA 2.55mA Fig.6: this graph plots the oxygen concentration against the Ip current for the lean measurement region where there is 0% or more remaining oxygen. Note that the current with respect to oxygen content is almost linear. The marked points on the graph have the values shown in the table. Fig.7: the temperature of the sensor cell is monitored by measuring its impedance using the circuit configuration shown here. Heater element control Apart from controlling the oxygen pump, the Wideband Controller also controls a heater element so that the sensor’s temperature is maintained at approximately 750°C. In fact, the sensor doesn’t provide accurate readings until this temperature is reached. There is no temperature probe within the sensor and so the temperature is measured by monitoring the impedance of the sensor cell. This has an impedance above 5kΩ at room temperature, falling to 80Ω at 750°C. We measure the impedance of the sensor cell by applying an AC signal to it. Fig.7 shows the circuit arrangement. A 5Vp-p (5V peak-to-peak) AC signal is applied to the sensor cell via a 220nF capacitor and 10.5kΩ resistor. The capacitor ensures that the sensor receives AC with no DC component and the resistor forms a voltage divider in conjunction with the impedance of the sensor cell. When the sensor cell is 80Ω, the voltage swing across the sensor cell is 37.8mVp-p. Amplifier IC5a has a gain of 4.7 so its output is 177mV peak-peak. The microcontroller maintains that value by controlling the heater current. siliconchip.com.au Fig.8: the heater element is controlled by a Mosfet that switches the power on and off. Temperature control is achieved by driving the Mosfet with a PWM signal to vary its duty cycle. Fig.8 shows how the heater is controlled. The gate of Mosfet Q1 is driven with a pulse width modulated (PWM) signal to control the heater current over a wide range. The Mosfet current is monitored via a 0.1Ω resistor in series with its source. The voltage across this resistor is filtered via a 22kΩ resistor and 100µF filter capacitor and fed to the microcontroller (input AN5). Should the heater become disconnected or open circuit, the lack of current will be detected and this will switch off the Wideband Controller functions. Similarly, if the heater current is excessive, the controller will switch off the heater. Note that when the Wideband Controller is first switched on, the heater must heat up gradually to minimise thermal shock to the ceramic sensor. Our circuit uses an initial effective heater voltage of 7.4V that rises at a September 2009  29 Fig.9: this diagram shows the general arrangement for the pump sensor control and the sensor cell measurement. Buffer stage IC4b supplies current to the pump cell via trimpot VR5 and the paralleled Rcal and 62Ω resistors. The other side of the pump cell connects to a 3.3V supply (formed using buffer stage IC2b and set by trimpot VR3 – see Fig.12). this higher effective heater voltage at start up will shave three seconds off the preheat period. This faster heat up requires a software change and this will be discussed next month. Note that we use the term “effective heater voltage” rather than “voltage” because the effective heater voltage is the RMS value of the pulse waveform applied by the Mosfet. In order to monitor the heater voltage, we also have to monitor the battery voltage which can be from around 12V before the engine starts up to more than 14V when the engine is running. As shown in Fig.8, the battery voltage is measured using a voltage divider comprising 20kΩ and 10kΩ resistors, together with a 100nF capacitor to filter out voltage spikes. To sum up, the impedance of the sensor cell is constantly monitored and as soon as it reaches 80Ω the preheat is complete and power to the heater is controlled to maintain this value. Once the sensor has reached operating temperature (750°C), the pump control circuit begins to operate. Pump sensor control Fig.10: this graph plots the Ip current versus lambda for the wideband sensor. The curve in the lean region (lambda = 1-1.84) was developed from the oxygen concentration graph shown in Fig.5 and the equation ((Oxygen percentage/3) +1)/(1 - 4.76 x Oxygen percentage) to give a 20-step piecewise linear graph. The intermediate values were then calculated by interpolating between adjacent calculated values. For the rich region, the 4-step graph provided by Bosch is used. rate of 73.3mV every 187.5ms. This is 0.390V/second and just under the maximum rate of 0.4V/s specified by Bosch. The initial effective heater voltage depends on the sensor temperature and ranges from 7.4V at -40°C to 8.2V at 20°C. The Wideband Controller 30  Silicon Chip always starts at the -40°C value. For a permanently installed sensor, heating can begin from a higher initial effective voltage of 9V at -40°C. This is provided that the sensor is installed in accordance with the mounting requirements specified by Bosch. Using Fig.9 shows the general arrangement for the pump sensor control. Buffer op amp IC4b supplies current to one side of the pump cell via trimpot VR5 and the paralleled Rcal (inside the wideband sensor) and 62Ω resistors. The other side of the pump cell connects to a 3.3V supply. When the output of IC4b is at 3.3V, there is no current through the pump cell. For positive current through the pump cell, IC4b’s output goes above 3.3V. Conversely, when IC4b’s output is below 3.3V, the pump cell current is negative. IC4b can swing between 5V and 0V, to allow for the current range required for the 1.84 to 0.7 lambda extremes of measurement. The pump cell current (Ip) is monitored using op amp IC5b which has a gain of 25.45. Fig.10 shows a graph of Ip versus lambda for the wideband sensor. The curve in the lean region (lambda from 1-1.84) was developed from the oxygen concentration graph shown in Fig.6 and the equation: ((Oxygen% ÷ 3) +1)/(1 - 4.76 x Oxygen%) to give a 20-step linear graph. For the rich region, the 4-step graph provided by Bosch is used. Another calculation is made to consiliconchip.com.au A Look At Narrowband Oxygen Sensors Narrowband oxygen sensors are installed on most modern cars. They are used to monitor the air/fuel ratio from the engine exhaust but they really are only accurate for measuring the stoichiometric mixture value. The stoichiometric mixture is where there is just sufficient oxygen for the whole of the fuel to be completely burnt. Under these conditions, a car’s catalytic converter can work best at converting combustion byproducts to less harmful compounds. Carbon monoxide (CO) is converted to carbon dioxide (CO2), unburnt hydrocarbons to carbon dioxide (CO2) and water (H2O) and nitrous oxide (N0) to nitrogen (N2). When a vehicle is running with a stoichiometric mixture, the engine management unit is constantly monitoring the oxygen sensor and altering the fuel so the mixture remains constant. The sensor output under this controlled condition tends to rise to around 480mV as the mixture goes ever so slightly rich before the ECU reduces fuel so that the mixture becomes very slightly lean at about 420mV. The sensor output therefore oscillates about the stoichiometric output at 450mV. Under these oscillations the system is said to be in closed loop. Richer or leaner mixtures from stoichiometric result in the sensor output voltage going much higher or lower than 450mV. However, the response from the sensor is very steep at stoichiometric such that the vert the lambda value to the voltage required at the wideband output as shown in Fig.4. Similarly, the lambda value is converted to an S-curve response for the narrowband S-curve output. This curve is shown in Fig.3. A further complication with the pump current is that it is dependent on exhaust back pressure. Fig.11 graphs the change in Ip versus pressure. This can be matched with the Lambda vs. Ip graph (Fig.10) to determine the effect on the readings. Note that exhaust pressure does not have an effect on stoichiometric readings because the Ip current is zero. Op amp IC5a monitors the sensor cell voltage. Its gain is 4.7. Trimpot VR4 is used to provide an offset voltage which is buffered by IC4a. VR4 is set so that IC5a’s output is 2.5V when the sensor cell voltage is 450mV. The misiliconchip.com.au sensors output can range from 150mV through to about 750mV with very little change in the mixture. The output response for a typical narrowband sensor is shown in Fig.3. For other mixtures (ie, when it is rich or lean), the sensor output can only be used as a guide to the actual air/fuel ratio. For rich mixtures there is unburnt fuel in the exhaust and a narrowband sensor produces a voltage that can vary from typically 0.75V to 0.9V, depending on the fuel mixture. For lean readings where there is excess oxygen in the exhaust, the sensor output will generally be below 150mV. When a vehicle is running in the rich or lean region, the control is said to be open loop where the mixture is not controlled. Rich mixtures are often set to provide improved acceleration response, while lean mixtures are often initiated during cruising to reduce fuel consumption. Additionally, the response within the rich region is very temperature dependent and can vary by several hundred millivolts between when the sensor is cold compared to when heated by the exhaust. Some sensors include a heater element but unless it is controlled to maintain a constant temperature, the mixture readings are inaccurate. For accurate rich and lean readings off stoichiometric, some other way of measuring the mixture is required. The Bosch LSM11 narrowband “lean” sensor provides a more accurate response to air/ fuel mixtures than most other narrow­band sensors and has been called a wideband sensor. However, this sensor is not a true wideband sensor and has the characteristic steep curve response at stoichiometric. It was the recommended sensor for use with our Air-Fuel Mixture Meter described in September and October 2000. Wideband sensors, however, introduce a new era for accurate air/fuel ratio measurements. Fig.2 shows how a narrowband zirconia oxygen sensor is made. It’s typically about the size of a spark plug and is threaded into the exhaust system so that the sensor is exposed to the exhaust gasses. The assembly is protected using a shield that includes slots so that the exhaust gasses can pass through into the sensor. The sensor itself is made from a zirconia ceramic material that has a thin layer of porous platinum on both sides. These platinum coatings form electrodes to monitor the voltage produced by the zirconia sensor as the exhaust gas passes through it. The device operates by measuring the difference in oxygen content between the exhaust gas and the outside air. The oxygen content of the air (about 20.9%) serves as the reference. In operation, a voltage is produced between the electrodes because the zirconia sensor has a high conductivity for oxygen ions at high temperatures. Fig.11: this graph shows how the Ip current changes with pressure. This can be used in conjunction with the Ip Current vs Lambda graph (Fig.10) to determine the effect on the readings. September 2009  31 32  Silicon Chip siliconchip.com.au 10 100 F 22k G A K 4 1k 5 Vss IN 100nF RB1 RB2 AN0 RA7 AN6 RA6 RB5 RB4 PWM 7 8 B Q2 BC327 A D1 HEAT LED1 470 17 16 13 15 B 100 F K K  C E E K DATA  LED2 470 A B TP1 A 2.2k A A ZD1 K K 11 12k 82k 4.7k K A K A 1 7 22pF 2 3 10k +5V 470k LEDS TP5V E +5V Vs B C 8 TP7 4 IC4b 9 10 13 12 2 3 G D S IRF540N Vs/Ip 100k IC4, IC5: LMC6482AIN 2.2k BC327, BC337 470k 100k TP8 6 5 100nF 220nF 220nF Vs/Ip 22 F IC2: LMC6484AIN 220nF 150 IC5a 8 100nF 10nF 100nF D4 –2.5V 100k 100k (10.5k) 100 F D3 220nF D2 K 8 4 IC2b 100nF 6 5 D2-D4: 1N4148 K A 7 14 15 '3' 11 12 '0' E Vss Vee 6 A IC3 '1' 4052B '2' VR3 10k 16 Vdd COM 10 F 9 C 10 13 10 A 1nF 4.7k 100 F +5V 10 F 10 F 120 11 9 Vdd 18 AN1 2.2k Q3 BC337 VR1 500 ADJ OUT REG1 LM317T 100 F 16V 14 IC1 PIC16F88I/P AN5 RA4 RB0 AN2 MCLR AN3 TP GND 12 3 6 1 2 ZD1 16V 1W 10 OXYGEN SENSOR CONTROLLER 0.1  5W S 13V TO START TP2 JP1 IMMEDIATE OUT START JP1 IN JP1 K 7 D TP4 7 IC2c IC2d +3.3V IC2a IC5b GND IN TP0 3.3nF 560k 4 TP3 VR5 1k 8 14 1 OUT +8V OUT 7808 1 6 5 62 GND IC4a TP6 22k TP5 150 150 GND 22k IN REG2 7808 OUT ADJ 2 3 +5V IN LM317T VR4 5k 560k Ip Rcal WIDEBAND OUTPUT S-CURVE OUTPUT 10 F +8V Fig.12: the full circuit uses microcontroller IC1, several CMOS op amps (IC2, IC4 & IC5) and a multiplexer (IC3). The microcontroller monitors & controls the wideband oxygen sensor and drives the Wideband Display Unit. It also provides a narrowband (S-curve) signal output. SC 10k A D1 1N4004 S-CURVE VR2 RESPONSE 5k RATE 100nF 20k Q1 D IRF540N 2009 H– GND2 GND1 H+ +12V F1 5A OUT crocontroller monitors this voltage and varies the pump current accordingly. LED indicators Two LED indicators, Heat & Data, show the operation of the wideband sensor. During preheat, the Heat LED is continuously on until the sensor is up to operational temperature (750°C). After that, the Heat LED flashes once a second to indicate normal control. If the LED is not illuminated, then the sensor temperature is above 750°C which can occur for very high exhaust gas temperatures. The Data LED flashes each time the wideband output is updated. With constant data updates, this LED will be constantly lit. However, it may extinguish during an exhaust gas mixture change before current control is restored. If this LED flashes at a regular 1Hz rate then the data is in error. This could be because the lambda reading is over-range or the heater has become disconnected. In this later case, the wideband output defaults to a lambda value of 1 and the S-curve output is set at 450mV. Circuit description The full circuit is shown in Fig.12 and it is based on a PIC18F88-I/P microcontroller (IC1). Its features include a 10-bit PWM output and 10-bit analog to digital conversion. It runs with an internal 8MHz clock oscillator. The op amps used in the circuit are special. We have specified one LMC6484AIN quad op amp (IC2) and two LMC6482AIN dual op amps (IC4 & IC5). These have a typical input offset of 110µV, a high input impedance of more than 10 Teraohms (>10TΩ), a 4pA input bias current, an output to within 10mV of the supply rails with a 100kΩ load, and a wide common mode input voltage range that includes the supply rails. An LM317T adjustable regulator (REG1) supplies 5V to the whole circuit except for IC4. VR1 is adjusted so that REG1’s output is exactly 5.00V. The battery voltage is measured at the AN3 input of IC1 via a 20kΩ and 10kΩ voltage divider connecting between the 12V input and 0V. This divider results in a maximum of 5V at the AN3 input for a battery voltage of 15V. 5V is the upper limit for analog-to-digital conversion by IC1 to the maximum 10-bit digital value. siliconchip.com.au Specifications Power requirements: 11V to 15V. Nominally 12V at 5.7A peak at start up maximum. Typically 16W when heated. Sensor ageing: lambda at 1.70 ±0.15; lambda at 0.8 ±0.04. Reading accuracy: ~1%. Measurement range: 0.7 (rich) to 1.84 (lean) lambda. Sensor Heating: begins at an effective 7.4V and ramps up at 73.3mV/187.5ms and is equivalent to 390mV/s. Heat up period: < 22s from initial 20°C. Heater over current: 4A. Heater open circuit detection: if current is less than 390mA at initial power up. Heater PWM frequency: during ramp up, 15.26Hz; during heat control >2Hz. Heater maximum effective voltage: 12V after initial preheat and at 13V for <1 minute. Sensor temperature: Controlled at ~750°C using the 80Ω at 750°C impedance of sensor cell for the measurement. Sensor cell measurement: AC drive at 1.953kHz and 473µA. Sensor cell DC loading: <10µA. Wideband output: Linear 0-5V output for 0.7 to 1.84 lambda. S-curve output: simulates a 0.8-1.17 range following the Bosch LSM11 sensor curve. S-curve response: Adjustable from the wideband response rate to 1.2s more than the wideband response rate. Reading variation with pressure: see graph of change in Ip versus pressure. Reading response: 250ms to a 5% change in oxygen. WHERE TO FIND DATA • • Data for the LSM11 and the LSU4.2 sensors mentioned is available. For Bosch LSM11 and Bosch LSU4.2 sensors see http://www.bosch.com.au/ content/language1/downloads/Section_D.pdf Further data on the Bosch LSU4.2 is at http://www.ontronic.com/products/ doc/Bosch_LSU_4_2.pdf 15V converts to a digital value of 1023 while 8V converts to a value of 545. Trimpot VR3 provides the reference voltage of 3.3V which is buffered by op amp IC2b. This op amp drives one side of the pump cell, the Vs/Ip connection, via a 150Ω resistor which isolates the op amp output from the 22µF capacitor which is included to remove ripple on the Vs/Ip supply reference. A 10kΩ resistor provides DC feedback while the 10nF capacitor is included to prevent instability. Multiplexer drive signals IC1 delivers a 7.843kHz PWM signal to the common input pin of the 4052 multiplexer IC3 via a 4.7kΩ resistor. The 1nF capacitor to ground provides some filtering of this signal, removing the high-frequency components of the square-wave above about 33kHz. This reduces crosstalk between the three output channels at pins 11, 14 & 15. IC2d actually provides the DC voltage, after the PWM signal is filtered, to drive the S-curve output. IC2c provides the wideband (0-5V) output and IC4b provides the pump cell drive. Let’s look at this in more detail. The micro drives the A and B inputs, pins 9 & 10, of IC3 to select its output. With both A and B at 0V, the selected output is “0” (pin 12) which is not connected. However, this “0” output is selected each time the duty cycle of the PWM signal is changed to suit the three selected outputs at pins 11, 14 & 15. So the switching sequence for IC3 is 0, 1, 0, 2, 0, 3 and so on. Each output has a low-pass filter to convert the PWM signal to a DC voltage and this is buffered using the respective op amps. September 2009  33 cell voltage, Vs. As already noted, IC5a is set so that when Vs is at 450mV, its output is 2.5V. To do this, VR4 provides an offset voltage which is buffered using op amp IC4a. This means that IC5a can swing symmetrically above and below this level to drive pin 17, the AN0 input of IC1. Link settings All the parts except for the oxygen sensor and its input socket are mounted on a single PC board which fits inside a diecast case. The full assembly details are in Pt.2 next month IC2c & IC2d buffer the voltages for the wideband lambda output and Scurve signals respectively, while IC4b buffers the voltage for the pump cell current. The 220nF filter capacitors at the inputs to these op amps store the voltage during the periods when the respective outputs from IC3 are not selected. Extra supply rails IC4b is a special case because its output is required to swing from 0-5V to drive the pump cell. To ensure this, IC4’s positive supply rail needs to be more than +5V and the negative rail needs to be less than 0V. Hence REG2 provides 8V and a negative supply is produced using transistors Q2 & Q3, diodes D2 & D3 This is the Bosch LSU 4.2 wideband sensor that’s used in conjunction with the Wideband Controller 34  Silicon Chip and the associated capacitors. The circuit is driven by the RA6 output of IC1 generates a 1.953kHz square wave signal. Q2 & Q3 buffer this signal to drive the diode pump consisting of D2 & D3. The resulting negative supply is -2.5V. This means that op amp IC4 is not operating with symmetrical supply rails but that doesn’t matter; the supply rails are adequate to guarantee that IC4b can swing its output positive and negative as required by the micro. Diode D4 is there to hold the negative supply rail at +0.6V when the negative supply generator is not working, ie, when IC1 is not in circuit. Op amp IC5b is connected as a differential amplifier to monitor the voltage across the paralleled 62Ω and Rcal resistors. Its gain of 25.45 is set by the two sets of 560kΩ and 22kΩ resistors at pins 5 & 6, respectively. A 3.3nF feedback capacitor rolls off high frequencies and prevents amplifier instability. The output of IC5b is referenced to the Vs/Ip voltage (+3.3V) by the 560kΩ resistor between its pin 5 input and the output of op amp IC2b. As a result, when 0V is across the 62Ω resistor, IC5b’s output sits at 3.3V. Note that the Vs/Ip voltage is continuously monitored by the AN1 input (pin 18) of IC1. Op amp IC5a monitors the sensor Link J1 selects the in-car installation mode. This requires that the engine starts before any electrical heating of the sensor begins. This ensures that any water condensation in the sensor is blown out before electrical heating. This prevents thermal shock and possible damage to the sensor. Basically, the battery voltage must rise above 13V before heating begins. 13V indicates that the engine has started and the alternator is running to charge the battery. Once heating begins, the battery voltage can fall below 13V without switching off the heater. Without link J1 installed, the heater is driven as soon as power is applied. This is suitable when the wideband controller is used as a portable air/ fuel ratio instrument. This means that the sensor MUST be protected from moisture ingress and from physical shock when not in use. Mosfet Q1 drives the heater with a DC voltage derived from the PWM signal delivered from the RA4 output, pin 3, of IC1. Its source current is monitored via the AN5 input, pin 12. Note that the circuit uses two earths. One earth (GND2) is for the heater and the other (GND1) is for the rest of the circuit. These two grounds are connected to the car chassis via separate wires. Without this separate earthing, the switching current applied to the heater would cause inaccuracies in the measurements of voltage and current and for the wideband output. LEDs1 & 2 are driven via the RB1 & RB2 outputs of IC1 via 470Ω resistors. The MCLR-bar input to IC1 is the reset input and ensures IC1 is reset on power up. The S-curve output response rate is set using trimpot VR2. This can apply a voltage ranging from 0-5V on AN2 (pin 1) of IC1, corresponding to no delayed response when set at 0V through to a 1.25s response at 5V. That completes the circuit description. Next month, we will move onto construction and describe the settingSC up procedure. siliconchip.com.au Introducing OLED Displays By MAURO GRASSI Organic LED technology is now affordable for the hobbyist. In this article, we survey some available OLED screens and modules and give an example for a simple oscilloscope. O LED displays are becoming mainstream and are now commercially available at prices affordable for educational and hobby use. While the technology may still need further development to seriously challenge LCDs in the bigger sizes, OLED screens of modest sizes can be purchased in Australia from a number of distributors at comparable prices to LCDs. OLED screens emit light, rather than relying on backlighting like LCDs. For that reason they have a much wider viewing angle. They also use less power than LCDs, exhibit higher contrast, are lighter and can be manufactured on more flexible materials. All these advantages over LCDs are making them the display screen of choice. For example, mobile phones using OLED screens are now on the market. In Australia, 4D Systems have a range of OLED displays, including siliconchip.com.au modules and standalone screens. The modules are essentially a screen and an embedded graphics processor. By contrast, the screens contain a driver IC embedded in the flexi-cable connector and can be directly driven by a host microcontroller – see photos. Some driver ICs, like the SSD1339 used in the 4D OLED-282815 screen, have inbuilt graphics acceleration for drawing lines, rectangles and circles. This means that you can draw primitives, simply by writing commands to the display from a microntroller. Instead of having to control individual pixels to draw a circle you can simply send the opcode corresponding to the command to draw a circle. You also send the associated data like the coordinates of the origin and the radius. How the driver IC is used For those readers interested in incorporating a screen rather than a module, we will now give a brief overview of the driver IC. The biggest challenge for the hobbyist is the mechanical connection to the flexi-cable, especially since the connectors themselves are surface-mount. The interface to the SSD1339 can be either parallel or serial. The serial interface is SPI (Serial Peripheral Interface), with the D0 line being used as a clock and D1 being used as data. There are two parallel interfaces, to suit 6800 style and 8080 style processors. Each has an 8-bit data bus but they differ as to the control signals. The 6800 style bus uses a R/W line which acts as a write strobe when low and a read strobe when high, whereas the 8080 style bus has separate RD and WR lines, each active-low. The 6800 uses an active-high E strobe to latch data. For both modes, there is a further CS (chip select) input active low that acts as a master enable – no writing or reading occurs while September 2009  35 The reverse side of two 4D Systems modules. At left is the OLED-160-G1, with a 1.7-inch (43mm) display, while at right is the smaller OLED-96-G1, which has a 0.96-inch (24mm) display. ever CS is high. Furthermore, there is a C/D line that selects whether the data represents a command or data. When C/D is low, the data represents a command, while if high, it represents a data word. The command codes for drawing primitives as well as the initialisation sequence for the screen are outlined in the data sheet for the driver IC (SSD1339) and is available from 4D Systems’ website (www.4dsystems. com.au). Play sounds: the GOLDELOX modules can play strings of notes, including complex sequences. The PICASO modules are even better in this respect, as these can play WAV files from the memory card. Convert analog readings to digital: using an on-board ADC (Analog to Digital Converter), you can use it to read voltages, sensors and any other type of analog signal. Use simple I/O: there are also two general purpose I/O pins with myriad applications. Control a Dallas 1-wire device: you can also configure the available pins for the 1-wire Dallas protocol. The Dallas 1-wire protocol can transfer data to and from a compatible device using only one data line (and GND). The data line also supplies power to the component! There are many devices available that use the 1-wire Dallas protocol including temperature sensors, memory ICs including EEPROM, analog to digital converters and real-time clocks. 4DGL language 4DGL is a graphics-oriented language for use with the embedded graphics controllers on 4D Systems’ OLED modules. Developed by 4D Systems, it is available from their website together with an IDE (Integrated Development Environment) called 4DGL Workshop – see Fig.1. OLED modules You can purchase 0.96”, 1.5” or 1.7” modules named OLED96-G1, OLED128-G1 and OLED-160-G1 respectively. The numbers indicate the number of horizontal pixels. In this article, we’ll be using the 96 x 64 pixel, 0.96” module which is a passive matrix OLED module. Passive matrix displays are cheaper but more power hungry and have a slower response than active matrix screens. However, they are still suitable for many applications. Each module has a GOLDELOX embedded graphics processor, an ASIC (Application Specific Integrated Circuit) developed by 4D Systems that can also be bought separately (for volume runs and lower production costs). Some modules use another graphics processor, called PICASO. Some of what you can do with these modules include: Display bitmaps and animations: you can select to store bitmaps and animations to a microSD card that plugs into the back of the module. Once the files have been stored on the memory card, you can display them with a few lines of code. 36  Silicon Chip Fig.1: the 4DGL Workshop program running on a PC. This program is freely available from the 4D Systems website and is a complete development environment that includes a compiler for the 4DGL language, a programmer to upload the program to the module and a text editor for modifying the source code. siliconchip.com.au 4DGL Simple Oscilloscope Program #platform “uOLED-GOLDELOX” // A Simple Oscilloscope // SC 2009 #constant BLUE 0x059B #constant ORANGE 0xF3E0 #constant BLACK 0x0000 func main() var x, y, ox, oy, miny, maxy; gfx_Cls(); x := 0; y := 0; ox := 0; oy := 0; miny := 64; maxy := 0; pin_Set(ANALOGUE_10, 0); while(1) x:=x+1; if(x>=96) x:=0; ox:=0; y:=0; while(y<32) y:=pin_Read(0)/16; wend txt_MoveCursor(7, 0); txt_Set(TEXT_COLOUR, ORANGE); print(“Pk-Pk(mV): “, 51*(maxy-miny)); miny:=64; maxy:=0; pause(100); gfx_Cls(); endif y:=pin_Read(0)/16; if(y>maxy)maxy:=y; if(y<miny)miny:=y; if(ox!=0)gfx_Line(ox, oy, x, y, BLUE); ox:=x; oy:=y; wend endfunc siliconchip.com.au The OLED modules from 4D Systems work in two modes: serial or 4DGL mode. In serial mode, they accept commands from another microcontroller. You can use almost any off-the-shelf microcontroller to control the display using a list of inbuilt commands and a UART (Universal Asynchronous Receiver Transmitter). The inbuilt commands include putPixel and drawCircle, for example. Commands are sent in multi-byte packets, with the first byte being the instruction code and the rest of the bytes make up the data for the instruction. For example, for the putPixel command, you send the instruction and the x and y coordinates of the pixel to draw. In 4DGL mode, a program in the embedded graphics processor runs on power up. 4DGL is loosely based on C syntax, although it also retains elements from other languages. If you’ve done programming before, you will be in a good position to learn this new language quickly. As an example, we’ve written a simple oscilloscope program in 4DGL. The program can be loaded into the embedded processor using a serial connection or via a USB to serial interface. For the purpose of this demonstration though, we have used the OLED-96-G1 module on 4D Systems’ DEVBOARD-G1 which comprises a power supply, a USB interface, a joystick and a mini speaker. OLED oscilloscope The oscilloscope has a rudimentary trigger implemented in software and measures the peak to peak voltage of the signal. The analog signal is applied to one of the two I/O pins of this module. Note that this oscilloscope is for demonstration purposes only and its bandwidth is severely limited by the speed of the embedded graphics processor (which affects the sampling frequency) and the resolution of the display (which affects the display of the waveform). It is OK for signals up to around 150Hz. The input signal is coupled to the I/O pin via a capacitor and resistor. There are also diodes to clip any out-of-range signals, along with two resistors which bias the input at half supply. We have mounted the components for this on the mini protoboard SMART PROCUREMENT SOLUTIONS Unit 3, 61-63 Steel Street Capalaba QLD 4157 AUSTRALIA Ph (07) 3390 3302 Fx (07) 3390 3329 sales<at>rmsparts.com.au www.rmsparts.com.au o Resistors o Capacitors o Potentiometers o Crystals o Semiconductors o Optoelectronics o Relays o Buzzers o Connectors o Switches o Hardware o Chemicals & Fluxes WHOLESALERS  DISTRIBUTORS  KITTING SOLUTIONS     September 2009  37 Running the Oscilloscope program on 4D Systems’ DEVBOARD G1, in this case displaying a square wave . . . on the DEVBOARD-G1 - see photo. The program works by digitising the analog signal and using the resulting digital value as the y coordinate on the screen. Here’s an explanation of the program (printed on p37). The oscilloscope program explained line-by-line #platform “uOLED-GOLDELOX” The #platform command tells the compiler which hardware the code will run in. In this example, we are using an OLED screen with the GOLDELOX processor. // A simple Oscilloscope // SC 2009 The above lines are comments. As in C, the ‘//’ indicates a line of comment. Multi line comments can be enclosed within a block delimited by ‘/*’ and ‘*/’. # constant BLUE 0x059B # constant ORANGE 0xF3E0 # constant BLACK 0x0000 The above three lines define constants we will use in the code below. These are equivalent to #define statements in C. The string BLUE is defined to have the constant hexadecimal . . . here a sine wave . . . value 0x059B. You may also define values in decimal. The three defined strings represent colour values. 4DGL assumes a 16 bit colour value that is broken up into three groups of bits (5-6-5) that correspond to the intensities of the three colours R-G-B (Red, Green, Blue). In this way, 65,536 colours can be displays on the OLED screen. func main() ... endfunc These lines declare the beginning of a function. In this case, the main() function is where execution begins, as in C. Everything between this line and the ‘endfunc’ line at the end of the program is part of the main function. var x, y, ox, oy, miny, maxy Here we are declaring various variables that we will use later. The variable x, y are the x and y coordinates respectively of the point currently being traced on the display. The ox, oy coordinates are the previous values of these. The miny and maxy variables, as their names suggest, store the minimum and maximum y values over the cycle. The latter are needed to compute the peak to peak voltage of the waveform, which is displayed too. gfx_Cls(); This is a built in graphics function that simply clears the display. x y ox oy miny maxy := 0; := 0; := 0; :=0; := 64; := 0; These lines initialise the variables, notice that unlike C, the way to set a variable is to use ‘:=’. The screen coordinates begin at (0,0) which corresponds to the top left corner of the screen. The value of 64 for miny is the lowest value the 10-bit ADC conversion can have (after it is divided by 16). 4DGL currently does not support floating point numbers, so all arithmetic operations are integer operations. pin_Set(ANALOGUE_10, 0); One of the general input pins (there are two) is set to function as an analog input. The constant ANALOGUE_10 specifies that we will use a 10 bit conversion (you can also use 8 bit conversions). while(1) ... wend +3.3V Fig.2: the hardware for the simple oscilloscope. We’ve used an OLED-96-G1 module and a DEVBOARD-G1 development board from 4D Systems. The development board has a prototyping area in the form of a breadboard where we’ve added the additional components to bias the signal at halfsupply along with a measure of input protection. 38  Silicon Chip 1N5819 10k 10 F SIGNAL IN VDD IO1 470 1N5819 10k OLED-96-G1 MODULE GND siliconchip.com.au . . . a sawtooth wave . . . This defines a while loop which is the main loop of the program. The program will execute this loop indefinitely, as the constant in brackets is non-zero. This is similar to C except that the curly brackets to group the statements in the while loop are not used and the ‘wend’ (while-end) keyword is used as delimiter instead. x:x+1; Each time around the loop we increment the x coordinate of the sweep point. if(x>=96) ... endif This block is only executed once the horizontal sweep gets to the edge of the screen (remember we are using a screen with 96 columns, each a pixel). x := 0; ox := 0; y :=0; At the end of each screen sweep, we set the variables for a new sweep. while(y<32) y:=pin_Read(0)/16; wend These lines essentially block the program until the signal crosses the horizontal line defined by y=32. It functions as a rudimentary ‘trigger’ and holds periodic waveforms steady. txt_Movecursor(14, 0); txt_Set(TEXT_COLOUR, ORANGE); prin(‘Pk-Pk (mV): ‘, 51*(maxy-miny)); The function txt_MoveCursor sets the cursor position for text, the format is in (line, columns). Thus, we’ve sesiliconchip.com.au . . . and a triangular wave, all at 50Hz. lected the cursor to be set to the bottom of the screen and leftmost. The txt_Set function can be used to set a number of attributes that apply to text, such as the type of font or its colour. In this case, we’re setting the text’s colour to that defined previously by the constant ORANGE. Finally, we print out a string using the print function. It simply shows the peak-to-peak voltage. The scaling factor of 51 converts from the y value to a voltage level. miny:=64; maxy:=0 pause(100); gfx_Cls(); Now we simply set up the variables for the next sweep, resetting the minimum and maximum values and pausing for 100 ms. We then clear the screen ready for the next sweep. y:=pin_Read(0)/16 The pin_Read function converts the analog level on the pin indicated in its argument (ie, 0=IO1 pin) to an integer. Since we’ve selected 10 bit mode previously, the value returned will be in the range 0-1023. When we divide by 16, we’ll get a value between 0 and 64 which becomes the new y coordinate. if(y>maxy)maxy:=y; if(y<miny)miny:=y; These two lines update the running minimum and maximum values to later determine the peak to peak voltage of the waveform. if(ox!=0)gfx_Line(ox, oy, x, y, BLUE); ox:=x; oy:=y; The gfx_Line function draws a line from the point (ox, oy) to (x, y) in the colour BLUE. The conditional (ox!=0) means the line is drawn everywhere except at the beginning of the sweep. The last two lines then transfer the contents of (x, y) to (ox, oy), the latter will represent the previous sweep coordinates in the next phase of the sweep. With the specified input coupling network we show in Fig.2 you can view signals of up to 3.3V peak-topeak. Larger signals will be clipped by the input protection diodes. While it is a very simple project, it highlights how easy it is to write applications using these OLED modules. At the time of going to press, prices (excluding GST) of the OLED modules from 4D Systems ranged from around $60 (the one we used for the oscilloscope photos above) to around $230, the latter featuring a 70mm active matrix touch screen. The GOLDELOX processor was priced at around $12.00. For more information on 4D Systems’ OLED displays, visit 4Dsystems. com.au SC A NOTE TO SILICON CHIP SUBSCRIBERS Your magazine address sheet shows when your current subscription expires. Check it out to see how many you still have. If your magazine has not turned up by the first week of the month, contact us at silchip<at>siliconchip.com.au September 2009  39 At Last... Review by Geoff Graham An AFFORDABLE Logic Analyser If you ever yearned for a logic analyser you will know how expensive they can be, with professional units costing $5,000 or more. The good news is that a new crop of more affordable devices is becoming available and a good example of these is the Logic, from US company Saleae. It costs just US$149 and even after Australian dollar conversion that price is very attractive. 40  Silicon Chip siliconchip.com.au Fig.1: this screen shot shows a typical capture without analysing the data streams. You can type your own labels to identify the signals into the boxes on the left. The buttons down the left let you select the trigger conditions. Logic can monitor eight signals. Each input is supplied with gripping type probes to hold onto IC pins. The colours used for the wires matches the colours used in the software to identify the inputs. W hat do you get for your money? Logic has eight channels that can record millions of samples at up to 24MHz. You also get a software package that includes decoders for I2C, SPI, serial (eg, RS232) and other data streams. It communicates with your computer via USB and it uses your computer to do the analysis and display. Logic analysers If you are new to digital circuits then you may not know just what a logic analyser is and why you might need one. Simply put, a logic analyser is like a multi-channel oscilloscope that displays logic levels (ie, high voltage or low voltage) rather than tracing the actual voltage. So why not just use an oscilloscope? Because a logic analyser is optimised for investigating digital circuits, it has multiple channels, making it easy to measure timing differences and it can decode the data streams that are transmitted and received. Let’s say that you are developing a circuit which uses a microcontroller and a chip that communicates via SPI (Serial Peripheral Interface). Many chips use SPI to communicate, including memories, displays, accelerometers and sensors. You dutifully read the data sheets, build a prototype, write the code and… it does not work. Hmm... what next? SPI uses four data lines to communicate. These are chip enable, clock, data in and data out. So you pull out your oscilloscope and check the various lines and observe “something” on each line. The first problem is that the signal is fleeting. There might be a burst of data when the program initialises but then nothing. With most oscilloscopes you need a repetitive signal to keep the trace on the screen long enough for you to see what is going on. Another issue is that most oscilloscopes are restricted to two inputs and while they can show you parameters such as the pulse rise time, clock speed and voltages, they say nothing about the data being transmitted on the lines. So, while you see something, you are not sure what it means. This is where the logic analyser comes in. It has multiple channels so that you can simultaneously watch all four data lines. It will store the trace data in its memory so that you can catch that brief burst of data and it will decode the data so that you can see just what is being sent. If you look at Fig.2, the top four lines show a captured SPI communication. The top line is Enable, the next is Fig.2: this is the same logic trace shown above with two of the analysers turned on. The upper four traces represent an SPI interchange while traces 6 and 7 are a decoded I2C stream. The software shows the value of the data byte in a coloured bubble. siliconchip.com.au September 2009  41 Fig.3: this screen shot shows the Logic software with the cursor pointing to part of a trace. In the bottom right hand corner you can see the related measurements. For example, the width of the pulse is a little over 29 S. the clock, then data in and finally data out. The coloured bubbles show the value of the data being sent. So now you can ask yourself, is this data stream correct? Does the timing match the data sheet? Is this what I was expecting? Because a logic analyser will capture the whole conversation, you can scroll back and forth through the data at your leisure – from the first initialisation through to the end. data directly down the USB interface to the computer. Your computer saves this data stream in memory and when the capture is complete, displays the result. Using your computer to do most of the processing is one of the secrets behind the low price. Having only eight input lines is one aspect where the Logic does restrict you. For example, many displays have an 8-bit bus and six control lines and it would be nice to monitor them all. Expensive logic analysers with 32 bits of input can do this and offer other frills such as being able to set the threshold voltage on the inputs. Logic Performance Despite its confusing name, Logic has a lot going for it. For a start, it has been designed with a sense of aesthetic values. The entire device is embedded in a small block of what looks like solid aluminium engraved with the product name. At one end is the USB connector and at the other end a 9-pin connector for the eight inputs and ground. The software is slick, with translucent effects that mimic the look and feel of Vista. The analyser works by grabbing the current logic level on its eight input lines and pumping that Because Logic has minimal buffering, its performance is very dependent on the speed of the USB interface. With a modern, fast computer and little traffic on other USB ports you should be able to capture data at the maximum of 24Mbits/sec. This speed is not guaranteed however and if the USB interface cannot keep up, the analyser will drop back to slower speeds. At 24Mbits/sec the analyser will sample the input lines Fig.4: logic analysers are good for showing the relationship between different signals. In this case the software has calculated that the difference between the falling edges of D1 and D3 (marked with timing markers T1 and T2) is 1.875μS. Sometimes knowing a detail like that can make the difference between getting a circuit to work or not. 42  Silicon Chip siliconchip.com.au every 42 nanoseconds. In practice, this means that you can use it to analyse circuits that are being clocked up to 15MHz or so. This covers most microcontrollers that hobbyists are likely to use. Even fast chips like the PIC18F2550 can only toggle their outputs at a maximum of 12MHz. Having said that, there are faster chips out there, like the new 32-bit series from Microchip that can toggle their outputs at 80MHz. Because your computer is used to store the captured data you can record a very large number of samples. This is a great plus and something that is not available in a standard logic analyser which generally has a limited amount of internal memory. As an example, with a capture speed of 12MHz this device can capture up to 82 seconds of data (50 million samples). This means that you can set the analyser to trigger at power on and capture everything that happens for the next 90 seconds. This is invaluable if you want to investigate an event that only happens once and a long time after power up. Compare that with an oscilloscope that can only show you something that happened a few thousandths of a second after the trigger point. Logic will also capture the activity on its inputs immediately before the trigger, so you can go backwards in time to see what led up to the trigger. Fig.5: a handy feature is that you can select from a wide range of sampling speeds and sample sizes. Because the software uses your computer’s hard disk to save the data it can record a considerable number of samples. Software Because Logic leaves most of the complex processing to your computer, the software and its usability become quite important. This is an area where the cheaper manufacturers often fall behind; they may produce good hardware at a good price but frequently the software is a disappointment. Not so with the Logic. The software is full featured and easy to use. The screenshots show you what the software looks like. In keeping with the careful design of the product the colour coding of the labels matches the colour of the wires in the probes. You can also type in your own labels to identify the signals. Sampling speed and depth is selected by buttons across the top while triggering is selected by the buttons down the left. The trigger conditions are quite flexible and allow you to trigger on a combination of high/low levels as well as rising/falling edges on all inputs. You can easily zoom in to see details or out to see the whole picture. You can also quickly scroll forwards and back through time by clicking and swiping your mouse sideways. Parameters such as pulse width, frequency and duty cycle can be read by pointing with the mouse. You can also drag and position two markers to make accurate timing measurements. Menu functions allow you to export and import the data in various formats. You can also save the data and later reopen it. This allows you to work with the captured data just as if you were still connected to the circuit under test. Analysers The software has the ability to decode a number of common protocols used for communications between “intelligent” components. These include I2C, SPI, serial siliconchip.com.au (eg, RS232) and one-wire protocols. This shows just how good a value this device is. Many brand-name logic analysers make you pay hundreds of dollars for the software module to decode just a couple of these protocols – and that is more than the complete price of this logic analyser including the hardware. Using the analysers is reasonably simple; you just specify what signals are on what inputs, select some options and the software will draw an overlay over the display showing the values of the data transmitted/received. You can also use a number of analysers to track multiple communications simultaneously. If you would like to test the program and the analysers before committing you can download the software from the manufacturer (address below) and run it in simulation mode. At the moment it is available for Windows only but Macintosh and Linux versions are reportedly in development. Summing up Having access to a logic analyser can save you untold hours of frustration when debugging digital circuits. And Logic is just the tool to save you that frustration. It is fast, easy to use and does the job without any fuss. As you might expect, it does have some weak points. Eight bits of input is rather limiting, it is dependent on the speed of your USB and it is missing some nice points that a more expensive logic analyser would have. For US$149 (less than $AU190 at press time) you cannot hold these points against the Logic. It is great value and will do 95% of what a hobbyist would need. If you are working with digital circuits you should have a logic analyser and if you are on a limited budget then this little gadget is recommended. Logic is available from the manufacturer, Saleae at www. saleae.com or from SparkFun at www.sparkfun.com SC September 2009  43 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. FireWire-sensing mains power switch Many new computers now come with rapid data transfer 6-pin Fire­ Wire ports (IEEE-1394). Alternatively, you can add them by purchasing a PCI card for about $30. They are commonly used for video transfers and sending data to external hard drives. Both these and USB ports provide A discrete op amp for audio use This circuit is a discrete op amp with a class-A output stage. It can be used as an alternative to op amp ICs in audio amplifiers. Low-noise transistors Q1 & Q2 (2SA970) act as a differential input stage with the emitter tail current supplied by current source Q5. Current mirror pair Q3 & Q4 act as collector loads for Q1 and Q2 respectively. This arrangement will improve DC offset and slew rate compared with conventional resistor loads. 44  Silicon Chip power to run the device attached to the port. However, when the computer is powered down the voltage at the FireWire port goes to zero whereas the voltage at the USB typically remains at +5V. In theory, if you want to switch off peripherals, all you have to do is wire a relay across the FireWire power and use it to control the mains power for the external devices. The only drawback with this ap- proach is that the output voltage from the socket isn’t defined and can vary between 12V and 25V, depending on the brand of computer. This problem can be solved with an external 12V power supply to power the relay switched by a transistor that monitors the FireWire socket voltage. When the computer is on, the voltage at pin 1 of the FireWire port switches on transistor Q1. This energises the relay and provides power to the peripherals. Conversely, when the computer powers down, Q1 switches off, de-energising the relay which removes the power to the peripherals. The circuit shows a conventional DC power supply using an 18VAC centre-tapped transformer, two 1N4004 diodes and a 2200µF filter capacitor. However, you could substitute a 9V or 12V DC plugpack. Note that you will need to disable “resume by USB” and “Wake-up by PME# of PCI” in the power management set-up of the computer’s BIOS. If you don’t, the computer will start up again when the power to the peripherals is switched off. Les Kerr, Ashby, NSW. ($30) Q6 is the voltage amplifier stage and this drives emitter follower output stage Q9. Q8 acts as a current source for the emitter of Q9 and it sets Q9’s operating current. Q7 is the current source for the collector load for Q6, to ensure good linearity. LED1 is a 3mm red LED, used here as a voltage reference for the three current sources Q5, Q7 & Q8. To the right of the discrete circuit is an op amp symbol showing a typical connection method. It is recommended that AC-coupling be used. Most components are readily available from Jaycar Electronics or Altronics except for the low-noise transistors Q1, Q2 & Q6 which are available from www.futurlec.com Alternatively, for a slight degradation in noise performance, Q1 & Q2 can be BC549s while Q6 can be a BC547. All resistors are 0.5W 1% metalfilm types, while C1 is an NPO cer­ amic capacitor. The supply voltage can range from ±6V to ±20V. Finally, the amplifier has wide bandwidth and is unity gain stable. Careful layout of the circuit is necessary to avoid oscillation. Alex Sum, Eastwood, NSW. ($50) siliconchip.com.au Temperature sensing battery charger cut-out Many tools and appliances with rechargeable batteries do not monitor the charge state and can easily overcharge the batteries if they are left connected for a long period. While a time-out can prevent an excessive charge period, it will not necessarily prevent overcharging. The circuit relies on the fact that as nicads or NiMH cells approach full charge their temperature rises. Two temperature sensors are employed. TS1 measures the ambient temperature while TS2 measures the temperature of one of the cells in the battery pack. If you cannot access the interior of the battery pack (eg, in battery-powered shavers), attach the second sensor (TS2) to the outside of the case with an elastic band. Op amp IC1 is connected as a comparator and monitors both TS1 and TS2. The voltage across both sensors can be adjusted using trimpots VR1 & VR2. When the temperature of both sensors is the same, VR1 could be adjusted for, say, 4V at pin 13, while VR2 is adjusted so that pin 12 is less than pin 13. When the battery on charge gets warm, its sensor voltage will rise and the comparator’s output will switch from low to high and turn on transistor Q1 which powers the relay. The relay has two sets of change­ over contacts rated at 240VAC. One set is connected in series with the ap- pliance, (eg, shaver) while the other is arranged to latch on the relay via the 22kΩ resistor to the base of Q1. Finally, the circuit shows IC1 as from an LM324 quad op amp but any general-purpose op amp could be used. John Malnar, Banks, ACT. ($40) This discrete audio op amp has wide bandwidth, is unity gain stable and can operate on supply voltages ranging from ±6V to ±20V. siliconchip.com.au September 2009  45 Circuit Notebook – Continued 6-digit PICAXE timer This 6-digit timer can provide time intervals in excess of 99 hours with accuracy to within a second. The heart of the project is a PIC­ AXE28X1 microcontroller, with all of the tricky logic contained in the program, leaving a minimum amount of hardware to achieve all the functions. A ULN2803 Darlington array drives the common cathodes of the 7-segment displays, the relay and the buzzer. Since the Darlington array includes internal diodes from each uncommitted collector output to the positive supply pin, no spike suppressing diodes are required for the buzzer and relay. S1 is the mode switch to allow the desired time interval to be set. Each digit is set individually using switch S2. This taps a voltage divider of 4.7kΩ resistors and is connected to the ADC input (A0) of IC1. Each digit is incremented to the desired setting by pressing push­button S3. If, for example, the “hours” digit is selected by setting S2 to position “H”, only the hours digit will be illuminated and it can be incremented using S3. Note that in keeping with the minutes and seconds format, the “tens of minutes” and “tens of seconds” can only be incremented to “5” before cycling back to 0. When the required time interval has been entered, switching S1 to the “Run’ position will commence the timing interval. The display then counts down with all six digits illuminated. During this time, the relay is activated and can be used to turn on a mains-powered device. The segment lines to the displays are driven by a 4511 BCD to 7-segment display driver, operating from a 12V supply. Transistors Q1-Q4 provide level shifting from the 5V signals of the PICAXE to the 12V drive required by the displays. The transistors also introduce a phase inversion but this is taken into account by the software. Outputs C1C4 from IC1 provide the necessary phase-inverted BCD output. At the completion of the timing period, the relay is switched off and a buzzer sounds to indicate that the timing interval has elapsed. Also, as a visible indication that the time is up, the seconds digit only is illuminated and flashes at about a half second rate. Switching S1 back to “Set” turns off the buzzer and prepares the timer for a new timing cycle. For long-term accuracy, the timebase is locked to the 50Hz mains frequency and requires no setting up or adjustment. A half-wave rectified 50Hz signal is provided by diode D3 and this is clipped by 4.7V zener diode ZD1 before it is fed to the counter input (C0, pin 11). The software then simply counts 50 pulses to obtain its timing for 1-second intervals. Jack Holliday, Nathan, Qld. Relays can do it by themselves Electronics people typically think of using transistors or ICs to drive relays, particularly if they need to be latched or periodically opened and closed. However, relays with changeover contacts can be connected to provide those functions without any active components being required. For example, a relay can be made to latch on or off, in response to two pushbutton switches, as shown in Fig.1 at right. Pressing the ON button S1 energises the relay, with current for the coil flowing through S1 and the normally closed switch S2. One set of relay contacts then supplies current to the load while the other set of contacts allows the coil current to continue flowing even after S1 is released. Hence, the relay is latched on and will stay on until switch S2 is pressed to break the circuit. In the second circuit (Fig.2), a relay with two sets of changeover contacts is arranged to operate a pair of alternating lights. One set 46  Silicon Chip of contacts alternately powers each 12V lamp while the other set provide the on/off function in conjunction with a 2200µF capacitor and 180Ω resistor. When power is first applied, current flows via the relay coil to charge the 2200µF capacitor and this briefly operates the relay, until the capacitor current falls to a low value. The relay then de-energises and the normally closed contact connects the 180Ω resistor to discharge the capacitor. The capacitor can then charge again via the relay coil which closes. This cycle repeats indefinitely. In each case, a diode across the relay coil is used to damp the voltage spike which is generated as the current through the coil is interrupted. While you may think the diode is unnecessary since there are no active components like transistors to be damaged, the undamped voltage spike may otherwise be sufficiently energetic to cause sparking on the switch or relay contacts. A. J. Lowe, Bardon, Qld. ($30) siliconchip.com.au This timer circuit is based on a PICAXE28X1 microcontroller and can provide time intervals in excess of 99 hours with accuracy to within a second. A 6-digit 7-segment LED display shows the initial setting and counts down to show the time remaining. Jac is th k Hollid ay is winn month’ s e Pea k At r of a l a s Inst rum Test ent siliconchip.com.au September 2009  47 Circuit Notebook – Continued High-current voltage doubler The circuit was developed to run a 24V marine radio from a 12V battery supply. It is basically a push-pull inverter based on 2N2955 power transistors Q1 & Q2, together with a bobbin-core transformer which runs at a high frequency. The transformer has an interesting configuration whereby the output windings also supply the base current to the two PNP transistors. As the load requirement increases, the base current increases, thereby affording a simple voltage regulation feedback loop, the output regulator then being only required to main- tain an accurate voltage level at the output. The bobbin-core transformer is bifilar wound, with the independent collector and base windings connected in series and the centre connections becoming the centre taps. The input voltage is doubled by virtue of transformer action and the 3-terminal regulator voltage is selected as required. The 78xx series regulators will supply up to 1.5A. Ultimately, the inverter’s output is limited by the base current rating of the PNP transistors but that would only be the case if a higher output regulator was employed. No heatsinks are required for the specified transistors operating at up to 1.5A but the regulator will require a heatsink. If the circuit does not oscillate when assembled, either the base OR collector transformer leads should be reversed but not both! This will set the phase of the windings correctly. Additional RF suppression in the supply leads may be necessary when powering radio equipment. The circuit will automatically shut down when the output load is disconnected, drawing only a few microamps. It can therefore be permanently connected to the supply. It is useful for powering 24V equipment from 12V systems, stabilising the voltage from battery banks while under charge and boosting voltage when line loss is a problem. For separately regulated devices or for loads such as lighting, the regulator can be omitted. The prototype is used to power a Koden 24V marine radio from a 12V supply. Input current is 3.75A at 12V while the output is 23.5V at 1.8A. This represents a very acceptable level of efficiency. Dayle Edwards, Westland, NZ. ($45) Editor’s note: the transformer used by the author was an FX2242 which is now unobtainable. We suggest winding the transfomer on an ETD34 bobbin instead. This is then fitted with two ETD34-3C90 ferrite core halves and the assembly secured using ETD34 clips. These transformer parts are available from Farnell Australia. You will need 1 x 3056302, 2 x 3056387 and 2 x 105769. Contribute And Choose Your Prize As you can see, we pay good money for each of the “Circuit Notebook” items published in SILICON CHIP. But there are four more reasons to send in your circuit idea. Each month, the best contribution published will entitle the author to choose the prize: an LCR40 LCR meter, a DCA55 Semiconductor Component Analyser, an ESR60 Equivalent Series Resistance Analyser or an SCR100 Thyristor & Triac Analyser, with the compliments of Peak Electronic Design Ltd – see 48  Silicon Chip www.peakelec.co.uk So now you have even more reasons to send that brilliant circuit in. Send it to SILICON CHIP and you could be a winner. You can either email your idea to silchip<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. siliconchip.com.au S ’ D A D WISH LIST Buy Dad a Ferrari this Father's Day! SD Card Speech Recorder/Player Kit Superbly detailed & fully factory licensed, these RC Ferraris will give hours of fun for all ages. Pick from either 1:20 or the huge 1:10 scale 2008 F1 racer or GT California. They have 3 or 4 channels so you can race against each other, full function remote control and adjustable steering bias. Each has a rechargeable battery pack included for the car. Refer: Silicon Chip Magazine August 2009 With this kit, you can store WAV files on commonly available MMC/SD/SDHC cards. It can be used as a jukebox, a sound effects player or an expandable digital voice recorder. You can use it as a free-standing recorder or in conjunction with any Windows, Mac or Linux PC. The length of time recorded is limited only by the size of the card. Short form kit. 1:10 Scale RC Ferrari 2008 F1 • Remote requires 1 x 9V battery Cat. GT-3201 $89.95 1:10 Scale RC Ferrari GT California $ • Remote requires 1 x 9V battery Cat. GT-3203 $89.95 • Includes overlay PCB, SD card socket and electronic components • Compatible with SD, SDHC or MMC cards 1:20 Scale RC Ferrari 2008 F1 • Remote requires 2 x AA batteries Cat. GT-3207 $54.95 1:20 Scale RC Ferrari GT California $ 54 95 A step up from conventional rabbit ears with 28dB variable gain. Suitable for VHF, UHF, FM and DTV reception. Mains plugpack included. Solar LCD Clock with Calendar & Temperature • VHF: 54 - 239 MHz • UHF: 470 - 821 MHz • Base: 190(L) x 120(W)mm Ideal for home or office workspaces, this easy-to-read LCD clock has several additional handy features. Its large numerical time format and alarm function is complemented by a calendar date and temperature display in either Celsius or Fahrenheit. It's powered by 2 x AA batteries $ 95 with auxiliary solar cells to prolong battery life. Cat: AR-1761 Suitable for wall mounting. • Dimensions: 250 (H) x 250 (W)mm • Size of digits: 55mm high $20 Wireless Weather Station Notebook USB Cooling Pad An ideal solution if you have a notebook that suffers from overheating or poor air circulation. This notebook cooling pad simply plugs into your notebook's USB port and has an inbuilt 18cm cooling fan to dissipate $ 95 heat. Is quiet, has four non-slip pads and an Cat: XC-5210 ergonomically tilted surface. 13 Cat: LT-3133 Archiving Dad's old record collection couldn't be easier. Record LPs directly to an SD card or flash memory via USB without needing a computer or software. You can also simply use the deck for playback via the built-in amp and speakers or run stereo outputs to an external amp. 149 149 This highly advanced weather station features a touch screen panel that you can connect to your computer through USB for storage and a more accurate analysis of weather data. XC-0348 $199.00 44 95 • Belt-drive turntable $ 00 • Built-in amplifier (2 x 1.2WRMS) • Track repeat function Cat: GE-4057 • AM/FM radio • Dimensions: 350(W) x 300(D) x 130(H)mm Was $169.00 A feature-packed weather station for the enthusiast forecaster. The outdoor sensors will wirelessly transmit real-time indoor/outdoor temperature, relative humidity, rain, wind speed, wind chill, dew point, and barometric pressure. All minimum and maximum values with the date and time it was recorded are stored for your reference. Also available: Touch Screen Wireless Weather Station with USB $ USB/SD Turntable 34 Along with its storm warning feature, $ 00 you can set programmable alarms to Cat: XC-0346 alert you when certain weather parameters fall above or below a limit you determine. If you enjoy outdoor activities this is a great tool to inform you of ideal weather conditions. See our website for full details. Cat: KC-5481 VHF/UHF Active Indoor Digital TV Antenna FROM • Working headlights • Remote requires 1 x 9V battery Cat. GT-3209 $54.95 74 95 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. Three separate receiver outputs can be used for controlling different devices such as door strikes, relays, motors or lights. Up to 16 transmitters may be used with the one receiver so it's suitable for small-scale commercial applications. As it 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 shortform kit without case so you can mount it in the location or enclosure of your choice. UHF Rolling Code Receiver and one Transmitter Kit Cat KC-5483 $99.95 UHF Rolling Code Additional Transmitter Kit Cat KC-5484 $39.95 * Receiver 12VDC <at> 150mA (1A for door strike use) • Measures: 300(L) x 290(W) x 35(H)mm Free Call: 1800 022 888 for orders! Fo r T h e D a d W h o L o v e s H i s C a r Kevlar 2 Way coaxial Car Speakers With Dome Tweeters Precision RESPONSE Subwoofers The Kevlar cone series is renown for its strength and clean sound reproduction. Crisp and naturally smooth highs are reproduced by the soft dome tweeters, complemented with a 12dB/octave crossover. $50 6 x 9” • 75WRMS, 4 ohms • 90dB SPL <at> 1W, 1m • 55Hz-20kHz Was $149.00 $ 99 00 6.5” $39 • 75WRMS <at> 4 ohms • 89dB SPL <at> 1W, 1m • 65Hz-20kHz Was $119.00 $ • 50WRMS <at> 4 ohms • 89dB SPL <at> 1W, 1m • 80Hz-20kHz CS-2372 Was $99.00 Now $69.95 Save $29.05 $40 179 00 Cat: CS-2352 $ 199 00 Cat: CS-2354 $50 Component Car Speakers with Ribbon Tweeters Everything you need to install a good quality split system in your wheels. PMI/Kevlar® composite cones for maximum rigidity and response. Ribbon tweeters for crisp highs. Separate crossovers with screw terminals. Mounting hardware included. 79 95 4 x 50WRMS Response Car Amplifier 229 $ Each kit contains: 00 • 2 x woofer/midrange drivers Cat: CS-2338 • 2 x ribbon tweeters Specifications: • 2 x crossovers Frequency response: 60Hz - 40kHz • 2 x grilles Crossover: 12dB/octave Full range of cross-overs available in-store for every budget. This unit is a compact and super affordable 4-channel amplifier that can power an entire sound system and is ideal upgrade amplifier from a basic factory $ installed system. 219 Cat: AA-0422 Car Ribbon Tweeter with Crossover This is the excellent ribbon tweeter used in our component kit CS-2338. Flush or surface mount, ABS housing, mounting hardware and crossover included. • Power / channel <at> 4ohm 14.4V: 50WRMS x 4 • Power / channel <at> 2ohm 14.4V: 80WRMS x 4 • Power / bridged <at> 4ohm 14.4V: 160WRMS x 2 Steelmate Paging Car Alarm Unfortunately many car thefts happen because the thief gets the keys to the vehicle; this system minimises that risk with a coded disarm feature. When enabled, it allows the owner to select a 1 - 5 digit pin code that is entered via the remote control and is required to disarm the system. Like our previous systems, this unit also includes two way paging with rechargeable remotes. The alarm includes long range back-lit LCD paging remote control with integrated rechargeable lithium-ion batteries inside, vibrating motors for when the alarm is triggered and an alarm clock! A 12V cigarette plug charger is provided to keep your remotes topped up while on the go. $ For full range of features see website. Spare remote: LA-9017 $99.00 379 00 Cat: LA-9016 Wedge Base LEDs Pk 2 2 $ 05 Cat: CS-2374 Excellent LEDs for a wide variety of automotive applications. Two styles T5 & T10 both: • Colour: White • Rated voltage: 14V • Maximum voltage: 16V • Luminous intensity : 500mcd (T5); 1000mcd (T10) • Forward current: 15mA • Viewing angle: 60° T5 ZD-0308 WAS $6.95 NOW $4.95 SAVE $2.00 T10 ZD-0309 WAS $7.95 NOW $5.95 SAVE $2.00 Limited Stock 10" Subwoofer • 250WRMS <at> 4 ohms • 84dB SPL <at> 1W, 1m Was $219.00 ea 12" Subwoofer • 300WRMS <at> 4 ohms • 86dB SPL <at> 1W, 1m Was $249.00 ea Cat: CS-2378 5” High performance subwoofers with huge bass & SPL potential. Die cast aluminium chassis and Kevlar reinforced cones - these robust drivers seriously pump! $2 00 $ 4 95 Cat: ZD-0308 Was $6.95 • Frequency response: 3kHz - 40kHz • Crossover: 12dB/octave $ • Crossover size: 30(L) x 20(W) x 12(H)mm 69 00 Cat: CS-2339 7" LCD In-Car TV with Remote Featuring a motorised 7" TFT LCD screen, this unit fits into a standard automotive DIN opening and in addition to the TV function, it takes two extra video inputs and an input for a reversing camera. It also has composite video and audio output. Comes with full function remote. $ • Screen size: 7" • Display format: 16 x 9 • Resolution: 480 x 234 pixels • Power consumption: 24W • Chassis dimensions: 182(W) x 53(H) x 161(D)mm Was $229.00 $30 199 00 Cat: QM-3782 Indoor/Outdoor Dual Display thermometer Another of our handy miniature thermometers, this one displays the inside and outside temperature simultaneously in °C on its LCD screen. The unit will measure temperatures from -50°C to +70°C and is ideal for keeping track of the temperature when travelling, or for general use around the home. $ The outside temperature sensor is fitted to a 3 metre cable. 22 95 • Range: Indoor: -10°C to +50°C and Outdoor: -50°C to +70°C • Measures 115(W) x 28(H) x 30(D)mm • AA battery included (replacement battery use our SB-2424) Cat: QM-6326 All savings are based on original recommended retail prices. G e t R e a d y T o Ta k e A d v a n ta g e O f T h e S u n Massive Price Savings On Powertech Solar Panels Powertech Solar Panels These monocrystalline panels are more efficient than polycrystalline panels & are as strong and tough as the better known brands, but at a more attractive price. Sizes range from 5 watts to a massive 175 watts. WAS 12V 5W 12V 10W 12V 20W 12V 65W 12V 80W 12V 120W 24V 175W ZM-9091 ZM-9093 ZM-9094 ZM-9096 ZM-9097 ZM-9098 ZM-9099 $115.00 $175.00 $279.00 $639.00 $875.00 $1280.00 $1750.00 NOW SAVE $78.20 $119.00 $191.25 $433.50 $595.00 $870.40 $1190.00 $36.80 $56.00 $87.75 $205.50 $280.00 $409.60 $560.00 Solar Rechargeable LED Door Light with PIR SAVE UP TO 70% OFF ORRP* Here's a neat solution to lighting the entrance to your home. When it's dark, the PIR detects anyone approaching the door and automatically turns the LED lights on for them, then times out after 30 seconds. The batteries recharge during the day to provide light at night. No wiring needed. $ 95 39 Cat: SL-2750 • 3 x AA rechargeable batteries included • Dimensions: 98(W) x 165(H) x 135(D)mm Solar LED Spotlight Kit Add a light to the garden shed, carport, entrance door or even for a wandering pet. The 135 x 87mm solar panel mounts anywhere you can catch some rays and the 9 LED spotlight can be mounted wherever it's needed. The light has a PIR so that after dark it will detect movement and turn the light on, then automatically turn off after a time delay. • 3 x AA rechargeable batteries included • Cable length 3m Solar Charge Controllers with LCD $ Protect your valuable solar installation and maximise battery service life with our photovoltaic (PV) charge controllers. Microprocessor controlled with LCD, these chargers efficiently charge a vast selection of batteries for a wide range of solar panels. They even feature an equalisation mode for wet type lead-acid batteries, and automatically cycles once a month for 2 hours. 12V and 24V models available. • Real-time clock display • Display of system status: $ 00 - Charge current - Load current Cat: MP-3129 - Battery voltage - Temperature - Battery capacity $ 00 • Bulk, absorption & float charge status • LED indication of battery levels Cat: MP-3722 • Overload and short circuit protection • Overvoltage and reverse polarity protection 3 models available: $ 00 12V 20A Solar Charge Controller - MP-3129 12V 30A Solar Charge Controller - MP-3722 Cat: MP-3724 24V 20A Solar Charge Controller - MP-3724 Cat: SL-2752 Smart Solar Battery Charger This solar battery charger supplies 15V at around 100-120mA of current. This is enough to keep an unused 12V battery topped up. It's ideal for that second car, caravan, or boat. Housed in a plastic case, it has an output lead to cigarette lighter plug, with a LED, which illuminates when the solar panel receives a charge. Note, some cars will require this to be directly wired to the battery, as the cigarette lighter socket is disconnected $ when the ignition is switched off. 169 199 189 Portable Folding Solar Chargers - Great For Boating & Camping Take your solar power with you wherever you need it. Folding to a compact bundle, these versatile monocrystalline solar chargers will fit anywhere, but expand to a full size 10 or 20 watt solar charger. Each has a robust nylon fabric enclosure and cigarette lighter socket for powering whatever you need. They also have utility loops so you can tie them up in a convenient place to catch maximum sunlight. Two lead sets are included - one with a cigarette lighter plug and another that terminates to alligator clips. Ideal for camping, 4WD, boating, caravans or motorhome holidays. Two models available: 10W Folding Solar Panel ZM-9120 Dimensions: Open: 750(L) x 220(W)mm Folded: 250(L) x 100(W) x 40(D)mm 20W Folding Solar Charger ZM-9122 • Size: 370(L) x 160(W) x 20(D) mm 299 Cat: ZM-9120 Limited Stock $ 499 00 Cat: MB-3501 It’s time to take advantage of the sun with these great recreational solar package deals! Our monocrystalline panels are by far more efficient than polycrystalline solar panels, and are strong and tough against Australia’s harsh environment. Both packages come with solar regulators, to ensure you get the most out of the sun. Choose between these two fantastic package deals. over Package 1: 80 Watt 1 x 80W Solar Panel 1 x 12V 6A Solar Charge Controller 2 x Female PV Connector 2 x Male PV Connector Normally - $696.75 $ ZM-9097 MP-3128 PS-5100 PP-5102 $45 NOW 650 00 Cat: ZM-9300 Package 2: 160 Watt 00 29 95 Recreational Solar Package Deals Dimensions: Open: 965(L) x 362(W)mm Folded: 375(L) x 120(W) x 45(D)mm $ 39 95 2 x 80W Solar Panel 1 x 12V 20A Solar Charge Controller 3 x Female PV Connector 3 x Male PV Connector 1 x Solar Panel 'Y' Lead 2 Socket to 1 plug 300mm 1 x Solar Panel 'Y' Lead 2 Plug to 1 Socket 300mm Normally - $1351.55 ZM-9097 MP-3126 PS-5100 PP-5102 over $150 PS-5110 PS-5112 Cat: ZM-9122 Solar panel mounting hardware and batteries available separately. Check in-store or on our website. $ NOW 1200 00 Cat: ZM-9302 *ORRP - Original Recommended Retail Price Free Call: 1800 022 888 for orders! www.jaycar.com.au 3 Dad’s Wish List RC Mini Mosquito Helicopter with LEDs Remote Control Lamborghinis & Audi R8 This chopper looks like a mosquito and has green LEDs for eyes. It is fun, fast, and stable. Just hit the throttle and off it goes. 30 min charge time for 10 min flying time Distinctive in appearance, these supercars feature see-through engine bays and superbly detailed bodywork. Take your pick between a Lamborghini Reventón, Superleggera $ 95 or an Audi R8. All are 1:18 Scale. 59 Cat: GT-3692 • Adjustable steering bias • Built-in rechargeable 500mAh battery (recharge time 5-6 hours) • Each remote uses 1 x 9V battery • Suitable for ages 8+ $ 59 95 • Requires 6 x AA battery (SB-2425) • 170mm long • Suitable for ages 8+ Cat: GT-3694 $ 59 95 69 95 Cat: GT-3262 Cat: GT-3696 1:18 Scale RC Lamborghini Reventón 1:18 Scale RC Lamborghini Superleggera 1:18 Scale RC Audi R8 $ Chinook Remote Controlled Chopper GT-3692 GT-3694 GT-3696 Durable Boeing CH-47 Chinook IR chopper to take all the knocks of flying around the lounge room. Twin dual rotors for stable flight and easy-to-use 3-channel controller with up/down, left/right turn controls. A mains charger is also supplied. 4 Ch Mini RC Helicopter The smallest 4 channel RC helicopter on the market, Dad will love this little beauty! Surprisingly easy to control and stable in flight, it comes ready assembled with a true 4 channel remote. Running low on power? Just attach the helicopter to the IR remote to recharge it for 17 minutes, and you're up, up and away again. • 17 mins recharge for 5-7 mins flight time • Weighs 19g, 190mm long (220mm including blades) • Requires 6 x AA batteries (SB-2425) • Suitable for ages 14+ $ • Adjustable trim controls • Recharges in about 20 minutes for 8 minutes of flight time • Remote unit requires 4 x AA batteries (SB-2425) • Dimensions: 210(L) x 130(W) x 165(H)mm • Recommended for ages 8+ 79 95 Cat: GT-3279 $ 69 95 Cat: GT-3259 Novelties Dad Will Love Pole Dancer LCD Alarm Clock The pole dancer is back! When the alarm goes, your personal pole dancer goes into her routine, complete with light show and funky music. A bit of wholesome entertainment for the man who has everything! • Requires 3 x AAA batteries (SB-2413) • Backlit LCD • Snooze function • Dimensions: 120(W) x 200(H) x 100(D)mm $ 29 95 Cat: GE-4079 29 • 15m range • Requires 4 x AA batteries (SB-2425) • 1 x 12V battery for key fob (supplied) Limited Stock 29 95 Cat: GH-1122 $ 19 95 Cat: GH-1088 RC Burp Machine Military Helicopter Alarm Clock Having trouble getting up in the morning? This alarm clock is certain to fix that. Set the alarm and when the it goes off, the chopper makes lots of jet engine noises. It also launches the propeller into the air and it flies around the room. Finished in olive camo. Battery or mains powered. $5 $ 19 95 Great for Father's Day lunch. Place the burp box near your intended victim and set off random burps. They won't only be embarrassed they won't know who's setting them up. • 5 hilarious burp sounds • Requires 2 x AA batteries (SB-2425) $ 11 95 Cat: GH-1081 Cat: AR-1766 Coughing Lung Ashtray Designed to look like a pair of lungs! Bursts into a disturbingly realistic coughing fit when a cigarette is placed in it. Talking Swear Box Tired of Dad swearing and can't get him to stop? Introduce him to the talking swear box and he will soon change his bad habits. 4 $ • Requires 4 x AAA batteries (SB-2413) • Handy belt clip Replace Dad's old whoopee cushion with this remote controlled Secret Farter. Great fun at home or the office. 3 different realistic fart noises will keep your jokester Dad amused for ages. Now Dad can wake up to a realistic V8 engine-sounding alarm. Easy to use and attractive in design, it is sure to be a hit with any motoring enthusiast young or old. $ 95 • Realistic pedals for demo and clock controls • Spinning brake disc when the alarm is activated Cat: AR-1769 • Clock 120mm dia. • Requires 3 x AA batteries (SB-2425) • 3 x LR44 batteries included • Size: 160(W) x 105(H) x 60(D)mm Absolutely essential equipment for Dad's next corporate meeting! Next time someone starts going on about synergies, tipping points, end-state visions and stakeholder partnering, he can just turn on his Bullsh*t Detector and shut them up with one of nine anti-bullsh*t messages. RC Secret Farter V8 Alarm Clock • Requires 4 x AA batteries (SB-2425) • Suitable plugpack: MP-3145 • Measures: 335(L) x 70(W) x 80(H)mm Was $24.95 RC Bull SH*T Detector $ 19 95 Cat: GH-1316 • Requires 2 x AA batteries (SB-2425) • Measures: 130(W) x 115(L) x 45(H) mm GREAT GIFT FOR THE UNREPENTANT SMOKER $ 10 95 Cat: GH-1330 All savings are based on original recommended retail prices. Dad’s Wish List 6 Bottle Wine Cooler PERFECT GIFT IDEAS FOR THE MUSIC-LOVING DAD USB Turntable with Amp Help Dad store his best wines and keep them chilled in this wine cooler. It has a capacity of 18L, holding up to 6 wine bottles and uses Peltier thermoelectric modules to cool the wine bottles 18 degrees below ambient temperature. Perfect for the Dad who has everything! $ A great Father's Day gift for music-loving Dads. Copy classic LPs, 45s or even 78s straight to PC, or he can simply listen to his cherished record collection via the built-in amp and speakers. Finished in contemporary white piano finish with blue LED accents. 199 00 • Mains powered Cat: GH-1372 • Power consumption 56W • Quiet operation • Dimensions: 245(W) x 380(H) x 510(D)mm Limited Stock USB Photo Scanner $ Cat: GE-4056 This player includes a turntable, AM/FM stereo/mono manual tuning radio, automatic start-play cassette and a programmable CD player. Encased in a cherry wood finish cabinet with two front stereo speakers. See our website for specifications. $20 • 12"LPs & 7"EPs with 3 speeds 33/45/78 • Measures 390(L) x 360(D) x 260(H)mm • Ask how to back up your LPs to CD 199 00 $ Cat: XC-4910 179 00 Cat: GE-4063 Was $199.00 Fresnel Magnifying Lens with Led USB 2.0 DVD Maker MKII Surprise your Dad by turning his aging collection of VHS and Betamax video tapes into brand new video productions, or record live video straight to your DVD or CD burner. This new and improved version works with Mac & Windows, allowing you to publish your videos on to web application and many more features. 99 00 Retro Music Centre Preserve your cherished old photos by converting them to digital format with this easy-to-use USB photo scanner. Simply download the included software, connect the photo scanner to your computer via USB and you're ready to start scanning. With an 8 megapixel sensor and crisp white LED lighting, it will produce clear high-resolution scans quickly and easily. Bring the best out of your images with the ArcSoft Media Impression software, which converts your scans to JPEG or TIF format, and enables you to do basic photo editing such as crop, straighten, retouch and colour adjust. PC & Mac compatible. • See website for specs and system requirements. $ • RCA line outputs • USB cable and software included Was $119.00 $20 Keep one in your purse or wallet for those times when you forget your reading glasses. Can be used with or without the LED on. Battery included. Perfect for the Dad whose always losing his glasses! $10 • Dimensions: 80(L) x 50(W)mm $ 5 95 Cat: QM-3533 • Supports USB 1.1 & 2.0 Plug-and-Play • Stereo audio input via RCA connectors • Dimensions: 35(W) x 95(D) x 15(H)mm Was $99.00 $ 89 00 Please note that the battery will last for years, but the product is not designed to have the battery replaced once it goes flat. Cat: XC-4867 iPod ® /iPhone ® Accessories FM Transmitter with Dock for iPod® 5.1 Home Theatre Receiver with iPod® Dock & Remote Let Dad listen to his favourite tunes through the FM radio in his car - dock and charge your iPod ® at the same time. This nifty little unit stays in your cup holder and is powered by your car's cigarette lighter outlet. It's compatible with most iPod ® models, works with MP3 players, CD players and other media devices. Not much you can't do with this receiver - home theatre, stereo, or dock your iPod® and use it for karaoke. The remote control operates all the functions of the amp, receiver and a docked iPod ® • Analogue audio inputs & 2 mic inputs • Variable channel modes: 2 ch, sim 2.1, 3.1 & 5.1 • Power output: Front - 60WRMS x 2 • Rear, centre: 15WRMS • Subwoofer: 100WRMS • 435mm wide Note: iPod® not included Was $249.00 • Last frequency memory • Backlit LCD • Size: 82(Dia) x 78(H)mm Note: iPod not included ® $ 89 95 Cat: AR-1869 Car Charger for iPhone® This sleek, attractive car charger is suitable for all versions of iPhone® including the latest iPhone® 3G, and will also charge all the different iPod® versions. Fitted with a curly cord, it will easily fit in your glove box without making a tangled mess of wires. Finished in gloss black. Specifications: Input: 12-24VDC Output: 5VDC, 500mA $ 19 95 Cat: MB-3654 $20 $ 229 00 Cat: AA-0471 Dock Recorder for iPod® Record and encode stereo audio MP3 straight to your iPod ® - no computer required! Simply connect an audio source to the dock and record via the voice/memo recording mode. You can adjust the recording level and also sync to your PC via the USB port. • Suits iPod®, iTouch, Classic, Nano 3G and 4G • Mains plugpack included • Dimensions: 100(L) x 100(W) x 35(H)mm Note: iPod® not included Limited Stock $ 119 00 Cat: AA-0498 GPS/Mobile Phone Holder This handy gadget plugs into your cigarette lighter socket and adjusts to fit your GPS/PDA/Mobile phone. It also has a piggyback socket so you can use the outlet to power your device. Also includes a suction glass mount for alternative mounting. • Adjustable up to 102mm • 180° rotation • Also accepts mobile phones $ 34 95 Cat: HS-9002 Free Call: 1800 022 888 for orders! www.jaycar.com.au 5 Get Ready For The Party Season Green Laser Display System Speaker Covers Create a dazzling atmosphere at your next party with the green laser show. The unit comes fitted with a microphone that changes the pattern of the lasers to the beat of the music. $30 • 240VAC Adaptor • Inbuilt microphone • Dimensions: 230(L) x 155(W) X 60(D)mm $ Note: Not available in W.A. Was $299.00 269 00 Cat: SL-2935 Laser Light Shows Liven up any party with these truly portable take anywhere laser light shows. $30 Green Laser Show SL-2937 • 100 pre-set geometric patterns • Speed adjustment • Auto, manual or audio laser display controls • 10mW green laser • 532nM wavelength • 240VAC adaptor included Was $199.00 Protect your PA speaker investment, or keep the prying eyes of thieves away. Made from durable two-layer UV and water-resistant coated nylon, these covers will protect your speakers from the elements while being transported or from bumps and scrapes when in storage. Suits PA Speaker and Speaker/Amp CS-2514 or CS-2517 CS-2500 $24.95 $ 24 95 Cat: CS-2500 Suits 12" Foldback Speaker CS-2516 CS-2501 $24.95 Suits 12" Subwoofer CS-2518 CS-2502 $24.95 15" Party Speakers $ 169 00 Cat: SL-2937 $30 Red Laser Show SL-2924 • 12 pre-set geometric patterns • Auto or audio laser display controls • 5mW red laser • 700nM wavelength • Batteries included Was $79.95 $ Get ready for your next party! These specialised party speakers provide good performance in back yards, tents, party rooms or community halls etc. Although rated at 120 Watts RMS plus, they can be driven by amplifiers with modest outputs and still provide impressive sound. Overload protected. Cheaper • 15 inch woofer • Piezo tweeters 49 95 Features two separate channels, one for each microphone. The system includes 2 microphones and batteries, receiver unit, 14VDC plugpack and 1m 6.5mm mono plug to 6.5mm mono plug lead. Ideal for schools, churches, karaoke, weddings etc. $ 219 00 Cat: CS-2515 Cat: SL-2924 Wireless Microphone than hiring $ 219 00 Cat: AM-4078 USB MIDI Interface $ Connect any MIDI device to your computer: keyboards, controllers, instruments, sound cards, samplers, drum machines etc. Plug and play, no software or drivers required. MIDI in and MIDI out connectors. 39 95 Cat: XC-4934 • Wireless range: 60m • Frequency response: 40Hz - 18kHz • 210mm wide Limited Stock • Cable length 2m Limited Stock I.Mix Club USB DJ MIDI Controller All the features professional DJs require, like anti-shock, cue and seamless looping. Rack-Mount Dual DJ CD Player Mix, play and scratch your own MP3 tracks directly from your PC. The i-Mix gives you the control you lose when going from a traditional mixer to a laptop. It sends MIDI data from the controller to your DJ software without the inconvenience of mouse control. Complete with LE versions of Deckadance and Traktor 3 software. This is the ultimate tool for the performing DJ. Loads of features. See website for full list. • 2-deck controller • USB powered, no extra power needed • Totally portable, smaller and lighter than a laptop • 2 pro jog wheels • Pitch, search and scratch • 6 EQ filters with 6 kills Dimensions: Player unit: 482(W) x 90(H) x 255(D)mm Controller: 482(W) x 90(H) x 85(D)mm Limited Stock System requirements: Windows XP SP2 or Vista Pentium III or Athlon 1GHz 512MB RAM Dimensions: 360(W) x 202(H) x 45(D)mm $ 399 00 Cat: AM-4250 Rave Fog Machine Produces clouds of white fog on demand. Fantastic for use with laser light shows, mirror balls and other party lighting. Mains powered. • 70 cubic metres/min fog output • 800ml fog juice capacity • Measures: 330(L) x 160(W) x 140(H)mm • Backlit LCD • Variable pitch control • Full function IR remote control • Tactile silicone rubber buttons • Compatible with CD, CD-R, CD-RW, MP3 • Anti-shock buffer memory • Quality Japanese transports $ 99 95 Cat: AF-1214 $ 399 00 Cat: AA-0491 DJ Mobile 19" Rack Frame With a total of 18 units available, you'll be able to fit all your rack gear and keep it completely portable. Ideal for DJs, PA techs, sound engineers or guitarists with large rack setups. The top section can be rotated through a range of 45° for maximum flexibility. Sturdy steel construction with castors. • Steel construction • Hardware included • Dimensions: 530(W) x 1050(H) x 500(D)mm Note: Equipment not included $ 1 litre Fog Juice sold separately - AF-1212 $17.95 6 99 00 Cat: HB-6348 All savings are based on original recommended retail prices. Learning Books & Kits Short Circuits Learning Books Since its inception, the Short Circuits learning system has become the preferred platform from which students can confidently tackle the various levels of modern electronics. All books in the series are geared towards specific levels of electronic knowledge. Short Circuits Volume 1 - BJ-8502 VOLUME 1 Acts as an introduction to electronics, absolutely NO previous knowledge of electronics is needed! • Soft cover - 96 pages • 205 x 275mm $ 13 95 Cat: BJ-8502 Short Circuits Volume 2 - BJ-8504 VOLUME 2 Assumes the reader/constructor has knowledge up to the end of Shorts Circuits Vol 1. • Soft cover - full colour 148 pages • 205 x 275mm $ 13 Short Circuits Volume 3 - BJ-8505 • Soft cover - full colour 128 pages • 205 x 278mm VOLUME 3 $ The WattsClever Power Monitor allows you to understand your household power usage habits, and adjust them to reduce your carbon footprint and your electricity bill. Includes display unit, one sensor, transmitter unit, USB cable and mains power supply. • Wireless range: 50m • Frequency: 433MHz $ • Displays entire household usage and cost Cat: MS-6155 • Suitable for single or three phase • Spare sensors required for 3-phase systems (use 2 x MS-6156 - sold separately) • Data logging via PC • Downloadable software • Time and temperature display • Display unit: 140(H) x 90(W) x 70(D)mm • Sensor unit: 120(L) x 70(W) x 30(H)mm Was $199 $20 179 Electronics Demystified 95 Cat: BJ-8504 Extends the concept. After completing Volume 3, there would be no reason why you couldn't tackle virtually any construction project you desire! Mains Power Monitor This book starts at simple DC circuits, goes through AC circuits, impedance, reactance, power supply concepts, semiconductor basics, amplifiers, oscillators, RF, telecommunications and finishes on antennas. At the end of each chapter is a straightforward quiz (multiple choice) to make sure you are on top of concepts. This is the best-written technical book on novice to moderately advanced electronics we have seen. • 480+ pages soft cover • Dimensions: 230 x 185mm 19 95 $ 37 95 Cat: BM-7106 Cat: BJ-8505 Full range of Kit projects sold separately. SOLAR ELECTRICITY High Performance Electronic Projects for Cars This is a great book to find out all you need to know about solar energy if you are looking to use it in your home, caravan, or anywhere. You will learn about solar panels and how they work, how electricity can work for you, solar regulators, deep cycle batteries, inverters, panel mounting and wiring, and maintenance and use. All delivered in a comprehensive and up to date easy-reading manual. Australia's leading electronics magazine Silicon Chip, has developed a range of projects for performance cars. There are 16 projects in total, ranging from devices for remapping fuel curves, to nitrous controllers, and more! The book includes all instructions, components lists, colour pictures, and circuit layouts. There are also chapters on engine management, advanced systems and DIY modifications. $ 50 Over 150 pages! All the projects are available in kit form. Cat: BS-5080 •137 Pages, soft cover • Full colour pictures • Size: 254 x 183mm 22 $ 38 95 Cat: BE-1532 Battery Zapper Mk III Multi-Function Active Filter Module The popular battery zapper kit has gone through a couple of upgrades & this is the latest easier-to-build version. Like the original project from 2005, it attacks a common cause of failure in lead acid* batteries: sulphation, which can send a battery to an early grave. The circuit produces short bursts of high levels of energy to reverse the sulphation effect. The battery condition checker is no longer included and the circuit has been updated and revamped to provide more reliable, long-term operation. It still includes test points for a DMM & binding posts for a battery charger. Not recommended for use with gel batteries. A versatile active filter module that could be used as an active crossover in a speaker project, a low pass filter for a subwoofer, or a high or band pass filter by changing a couple of jumper links. Being an active circuit, you'll need to add a power supply (see specifications on our website) and amplifiers for the drivers. Short form kit only. You'll need additional components to configure it for your chosen power supply & operation frequency. • Voltage gain: adjustable from 0 to 2x • Filter slope: 24dB/octave or 80dB/decade • Input impedance: 47kohms $ 95 • Supply voltage: ±15 - 60VDC dual rail, 12 - 30VDC single rail or 11 - 43VAC Cat: KC-5480 • Current consumption: 40mA maximum • PCB with overlay and all common components included Refer: Silicon Chip Magazine July 2009 • PCB with solder mask, overlay and components included • Screen printed machined case • 6, 12 & 24VDC Refer: Silicon Chip Magazine July 2009 24 $ 79 95 Cat: KC-5479 Lead Acid Battery Health Checker 10A12VDC Motor Speed Controller The first versions of the battery zapper included a checker circuit. The Mk III battery zapper (KC-5479) has a separate checker circuit - and this is it. It checks the health of SLA batteries prior to charging or zapping with a simple LED condition indication of fair, poor, good etc. Ideal for controlling 12V DC motors in cars such as fuel injection pumps, water/air intercoolers and water injection systems. You can also use it for headlight dimming and for running 12V DC motors in 24V vehicles. The circuit incorporates a soft start feature to reduce inrush currents, especially on 12V incandescent lamps. Includes PCB and all electronic components. Refer: Silicon Chip Magazine August 2009 • Overlay PCB and electronic components included • Case with machined and silk-screened front panel $ 79 95 Refer: Silicon Chip Magazine June 1997 • Kit includes PCB plus all electronic components to build the 10A version. Cat: KC-5482 Free Call: 1800 022 888 for orders! www.jaycar.com.au $ 24 95 Cat: KC-5225 7 Tools Cat II 4000 Count Autoranging DMM Cat II Autoranging DMM This Cat II DMM is suitable for voltages up to 600VAC and has 15mm high digits for easy measurement. Features include overload protection, 10A AC & DC current, diode check, data hold,& backlit display. Just select the parameter you want to measure and the meter chooses the appropriate display range which you can override manually if you want to. It also does capacitance, frequency & diode test. • Display: 4000 count $ 95 • Category: Cat II 600V • Autoranging Cat: QM-1535 • Data hold • Relative measurement function • Auto power-off • Holster included • 10A AC & DC • Dimensions: 150(H) x 75(W) x 33(D)mm 34 • Display: 2000 count • Category: Cat II 600V $ 95 • Data hold • Back light Cat: QM-1524 • Diode test • Holster with stand & test probes • Dimensions: 140(H) x 70(W) x 31(H)mm 24 Much cheaper than the hardware store and with 400 pieces, this kit will service every bit you will ever need. Housed in a plastic case. • 32 range $ • Transistor test • Diode test • Audible continuity • Temperature • Capacitance • Display: 2000 count • Category: Cat II 600V • Dimensions: 200(H) x 95(W) x 45(D)mm 29 95 Cat: QM-1320 Ultra compact, non-contact thermometer. IP67 rated so is ideal for industrial and lab applications. LCD readout gives temperature in Celsius or Fahrenheit. Batteries and lanyard included. Contents includes sanding arbours, sanding belts, drill bits, collets, assorted grinding stones and polishing wheels with arbours, TC and diamond burrs, wire brushes, cutoff wheels, buffing mop with paste, paint removing wheel, 250 sanding discs and more. $ Features include extra large display with 25mm high digits, frequency, temperature and transistor tester. Also included is a protective holster with hanging clip and tilting bail, low battery indicator, overload protection & test leads. Mini Non-Contact IR IP67 Thermometer Rotary Tool Bit Set - 400pc • Case measures: 210(W) x 300(H) x 70(D)mm Frequency DMM • Measurement range: -33 - 110°C (-27 - 230°F) • Accuracy: ±1°C • Response time: 1 second • Size: 82(L) x 17(Dia) 59 95 Cat: TD-2456 $ 39 95 Cat: QM-7218 IT & Comms On-Line 1000VA 700W UPS The UPS provides a perfectly clean sine wave output no matter what the mains throws at it. You’re covered for surges, spikes, noise, brownouts and blackouts for as long as the batteries last. A backlit LCD shows you the operating status and advises you of any fault condition. It also provides an RS-232 interface so the UPS can be connected to a computer and used with the included management software. See website for full specifications. • Pure sine wave output • True on-line operation • 2 x 240V outlets $ 00 • Software included • Batteries: 2 x 12V 7Ah Cat: MP-5210 • Backup power: 1000VA • Backup time: 7 mins at 50% load • Dimensions: 400(L) x 145(W) x 210(H)mm Was $749.00 $50 00 • Standard QWERTY layout • Washable and hygienic • Supports Windows • Size: 370(L) x 123(W) x 15(H)mm 79 NEW SOUTH WALES Albury Ph (02) Alexandria Ph (02) Bankstown Ph (02) Blacktown Ph (02) Bondi Junction Ph (02) Brookvale Ph (02) Campbelltown Ph (02) Erina Ph (02) Gore Hill Ph (02) Hornsby Ph (02) Liverpool Ph (02) Newcastle Ph (02) Penrith Ph (02) Rydalmere Ph (02) Sydney City Ph (02) Taren Point Ph (02) 8 6021 9699 9709 9678 9369 9905 4620 4365 9439 9476 9821 4965 4721 8832 9267 9531 6788 4699 2822 9669 3899 4130 7155 3433 4799 6221 3100 3799 8337 3121 1614 7033 14 95 Cat: XC-5191 Life for business travellers and students just got a lot easier. Now you can have a convenient roll-up keyboard to take on the road or to lectures, and it’s wireless. Convenient size with splash resistant keypad, so is ideal for harsh environments or areas that have to be constantly cleaned such as sawmills, factories, workshops, food preparation areas. A SATA Docking station loaded with features. Dock your 3.5 inch or 2.5 inch SATA HDD and it will instantly mount on your computer as an external hard drive. It also features slots for a multitude of cards. CF/SD/MS and their variations can all be read. It also has 2 USB ports. An invaluable tool for cloning disks or debugging HDD problems. • Up to 480Mbps transfer rate with USB 2.0 $ 95 • Up to 3Gbps transfer rate with eSATA Cat: XC-4692 Note: HDD not included Tweed Heads Wollongong VICTORIA Cheltenham Coburg Frankston Geelong Hallam Melbourne Ringwood Springvale Sunshine Thomastown QUEENSLAND Aspley Caboolture Cairns Ipswich Mackay $ Mini Roll-Up Wireless Keyboard 2.5/3.5" SATA HDD Dock with Card Reader YOUR LOCAL JAYCAR STORE Portable USB-powered speakers for use with laptops, desktop PCs or mobile music players. Contemporary, space saving design with plug and play functionality. Separate volume control, power switch and headphone output, and as they're powered via your computer's USB, there's no need to use a plug pack or batteries. • Frequency response: 160Hz - 20kHz • Impedance: 6 ohms • Power output: 1.8WRMS • Dimensions: 154(H) x 75(W) x 36(D)mm 699 Australia Freecall Orders: Ph 1800 022 888 Compact PC Speakers Ph (07) 5524 6566 Ph (02) 4226 7089 Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph (03) (03) (03) (03) (03) (03) (03) (03) (03) (03) 9585 9384 9781 5221 9796 9663 9870 9547 9310 9465 5011 1811 4100 5800 4577 2030 9053 1022 8066 3333 Ph Ph Ph Ph Ph (07) (07) (07) (07) (07) 3863 5432 4041 3282 4953 0099 3152 6747 5800 0611 Maroochydore Ph (07) 5479 3511 Mermaid Beach Ph (07) 5526 6722 Townsville Ph (07) 4772 5022 Underwood Ph (07) 3841 4888 Woolloongabba Ph (07) 3393 0777 AUSTRALIAN CAPITAL TERRITORY Belconnen Ph (02) 6253 5700 Fyshwick Ph (02) 6239 1801 TASMANIA Hobart Ph (03) 6272 9955 Launceston Ph (03) 6334 2777 SOUTH AUSTRALIA Adelaide Ph (08) 8231 7355 Clovelly Park Ph (08) 8276 6901 Gepps Cross Ph (08) 8262 3200 WESTERN AUSTRALIA Maddington Ph (08) 9493 4300 Midland Ph (08) 9250 8200 Northbridge Ph (08) 9328 8252 Rockingham Ph (08) 9592 8000 GREAT FOR LAPTOP USERS $ 69 95 Cat: XC-5145 NORTHERN TERRITORY Darwin Ph (08) 8948 4043 NEW ZEALAND Christchurch Ph (03) 379 1662 Dunedin Ph (03) 471 7934 Glenfield Ph (09) 444 4628 Hamilton Ph (07) 846 0177 Hastings Ph (06) 876 0239 Manukau Ph (09) 263 6241 Newmarket Ph (09) 377 6421 Palmerston Nth Ph (06) 353 8246 Wellington Ph (04) 801 9005 Freecall Orders Ph 0800 452 922 Prices valid to 23rd September ‘09 Free Call: 1800 022 888 for orders! www.jaycar.com.au SERVICEMAN'S LOG Why do such things only ever happen to me? I try to avoid fixing computers when I can. They can be a right royal pain in the youknow-what and this job was no exception. Still, with CRT TV repairs rapidly going the way of the VCR and the dinosaur, I can’t afford to be choosy these days. This job all started when the boss of a local company brought in a computer that had been handed down to him from one of his employees. Apparently, this employee needs a fairly powerful machine for his work and so his old computer is always inherited by another staff member each time he talks (or should that be cons?) his boss into buying him a new machine. This particular PC was a fairly respectable Pentium 3GHz machine with 1GB of memory, a fancy graphics card and Windows XP Home as the operating system. But despite its specifications, it was running like a hairy goat. It was slow to boot up and once up and running, it was still painfully slow. It also had a very noisy power supply fan, something not surprising in a machine about four years old. The noise apparently didn’t bother the previous user who’s fairly casual about such things but there was no way his impatient type-A personality boss was going to tolerate it. He wanted the noise fixed and he wanted the operating system restored to full health so that the machine ran properly. When I subsequently fired it up, the siliconchip.com.au power supply fan was so noisy that I decided to fix it immediately. How­ ever, rather than swap the supply out for a new one, I decided to replace the fan itself with a good-quality ballbearing unit that I happened to have on hand. As a result, I removed the power supply from the case, opened it up and blew out the accumulated dust using an air-compressor. It was then just a matter of installing the new fan and remounting the supply. I also spent some time tidying up the supply wiring and securing it with cable ties. This not only looks neater but also allows the air to flow freely through the chassis to keep things cool. That completely cured the noisy fan so that was one problem down. Now to clean up the operating system. “This will be a snack”, I thought. Silly me! When it comes to computers, I should have known better – a whole lot better. To cut a long story short, I tried cleaning up the operating system (OS) by uninstalling all unwanted programs and running various registry cleaners but it still had problems. In the end, it was obvious that the quickest way Items Covered This Month • • • Resurrecting a computer Sony camera & memory JVC VM/PD-Z50DX4 plasma TV • LG 50PX4RA-TA plasma TV set • Volvo 940 GLE electronic speedometer out would be to reinstall the OS and so I took a brief walk down the street to the client’s office and picked up the original XP install disk. Unfortunately, they couldn’t also find the disk that came with the motherboard, which meant that the motherboard drivers would have to be downloaded from the net. That would be no big deal – finding the relevant drivers for a Gigabyte motherboard is easy. Back at the ranch, I reformatted the hard disk and then installed Windows XP and the motherboard drivers which I’d downloaded on another machine. I then applied the service packs after which I connected the machine to the Internet in order to install the latest security updates. And that’s when I hit hardware problem number two – the PCI network card suddenly stopped working. This was rather puzzling as the network card had initially worked perfectly. Now, after installing some September 2009  57 Serr v ice Se ceman’s man’s Log – continued security updates plus Java and a few routine utility programs, the driver was refusing to load. In fact, each time the machine now started up, Windows XP would announce that it had found new hardware (ie, the network card) and would prompt for the driver installation. Device Manager also showed that the network card was present but that the driver had failed to load, as indicated by a yellow exclamation mark next to the device entry. No problem, I thought – just reinstall the driver. The only problem was it wouldn’t let me, the machine stubbornly refusing to recognise the driver each time I attempted to install it. Swapping the network card into one of my own XP machines gave the same result, so I swapped in an identical network card which the company kept as a spare but that didn’t work either. Grasping at straws, I then tried reserving the IRQ for the PCI slot that the card was plugged into. Again it made no difference and I had now run out of ideas. Well, almost – it was time to take the easy way out (something I’m very good 58  Silicon Chip at). I ducked down to the computer store, grabbed a $12 generic network card and popped it in. It worked immediately, with XP discovering the card on boot-up and automatically installing the driver. So what was stopping the other network card from working? I “dunno” and what’s more I don’t want to know. Life’s too short to worry about it. A nasty surprise By now, everything was starting to look hunky-dory but this machine still had some nasty surprises in store. The next morning was cold and frosty and when I turned the machine on it refused to start. Instead, it just gave out a long beep followed by two short beeps and the power LED was flashing on and off. I left it on and then, after about five minutes, the machine started up and worked normally. Why do such things only ever happen to me? There are literally thousands of ways of making a living in this world and I had to pick this one! A quick call to the company revealed that the machine had been regularly doing this for about three years. It was perfectly OK during the summer months but as soon as the temperature dropped below about 20°C, it would always initially refuse to start. The staff member who was using the machine didn’t care – he simply came in, switched the machine on and waited patiently for the five or six minutes it took to warm up. This guy is never going to die of hypertension. But there’s no way that this delayed start-up would be tolerated by the boss. Instead, he would be more likely to blow a gasket and drop-kick the machine out the door and into the carpark. OK, this had to be some sort of temperature-sensitive fault so I removed the cover and took a look inside. And that’s when I spotted two electrolytic capacitors (3300µF 6.3V) with bulging tops on the motherboard. These capacitors were located close to some supply regulators and this particular brand are infamous for causing problems in motherboards of this vintage. They just had to be the reason for the delayed start-up in cold weather, so I removed the motherboard and replaced them. And while I was at siliconchip.com.au it, I replaced four other similar electrolytics as well. Of course, this is no 5-minute job and you have to be careful removing the capacitors so as not to damage the board. The machine started normally when it was all back together again but by now the workshop was nice and warm. That meant I couldn’t be sure whether the delayed start-up problem had been fixed or not but by now I was feeling pretty confident. It only took until next morning to find out that the problem was still there. Once again, when turned on, the machine gave one long beep and two short beeps and then sat there with the power LED flashing. I switched it off immediately while the fault was still present, so it didn’t have a chance to warm up. This time I did what I should have done in the first place. I downloaded the manual for the motherboard from the Internet and looked up the “beep codes”. This indicated a problem with the video card. Encouraged by this, I replaced the video card with a similar one from one of my own PCs and guess what – the machine now started normally. I then swapped the two video cards back and forth several times to confirm the result and each time the original card went back in, the machine refused to start. In the end, I left my card in the machine and that completely cured the cold start-up problem. However, the bulging motherboard capacitors would certainly have caused problems of their own further down the track, so replacing them was hardly a wasted exercise. Acting out of curiosity, I plugged their supposedly faulty video card into my own machine and was rather surprised when it immediately started up. It started the next morning as well despite the weather being quite cold and what’s more, it has kept on working. Why? I “dunno” again and what’s more I don’t want to know again. As long as the problem is fixed, then I’m happy. It’s just chaos theory in practice. IE is crashing By now, you would expect that that would be the end of it but this computer had one more poke in the eye left for me. After using it for a short time, it became apparent that Internet Explorer 8 (IE8) was unstable. For some reason, it would crash frequently, at the same time indicating a fault in either mshtml.dll or ntdll.dll – and this on a fresh install! I trawled the net and found lots of references to these two “.dll” files but nothing seemed to be all that relevant to this situation. I tried several suggestions without success and eventually decided to uninstall IE8 and see if that solved the problem. This takes you back to IE6 which I immediately upgraded to IE7 but the instability problem was still there. Next, I tried installing Firefox and discovered that this worked normally. However, I wasn’t about to give up on IE8, as it worked on my own computers without any problems. I trawled the net some more and eventually found a recommendation from someone to uninstall and reinstall the Flash Player. I did that and that was the cure, with IE8 now functioning perfectly. Apparently, it had been falling over on web pages with Flash content, probably due to a corrupted file. And that finally was it. Unfortunately, due to the time spent, I didn’t make a lot of money from the job and so I really could do with another $900 stimulus payment. I’m not holding my breath though. My new camera I am no whiz when it comes to photography and, until recently, have been using a Sony Cybershot DSC-P8 3.2-megapixel digital camera to take all my photos. This was bought secondhand about five years ago and it has been a great little camera. However, as I have grown older, my hands have become shakier and the long delay between pressing the button and the shutter closing (especially in poor light conditions) often now results in blurred pictures. In view of this, I recently decided to upgrade to a new camera which would eliminate this problem. The choice was mind-blowing, with the technology increasing exponentially with price. In the end, I settled on a very Australia’s Best Value Scopes! Shop On-Line at emona.com.au GW GDS-1022 25MHz RIGOL DS-1052E 50MHz RIGOL DS-1102E 100MHz 25MHz Bandwidth, 2 Ch 250MS/s Real Time Sampling USB Device & SD Card Slot 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 Sydney Brisbane Perth ONLY $599 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 $879 inc GST Tel 07 3275 2183 Fax 07 3275 2196 Adelaide Tel 08 8363 5733 Fax 08 8363 5799 ONLY $1,169 inc GST Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au EMONA September 2009  59 Serr v ice Se ceman’s man’s Log – continued diagram for this power supply, so I persevered without any data available. However, the only things I could find that were faulty were two open circuit 10Ω 5W resistors in the Power Factor Control circuit. In the end, there was nothing else for it but to fork out $700 for a new power supply which the client agreed to! LG plasma TV nice Sony Cybershot DSC-W290, a 12.1-megapixel camera with a 3-inch (76mm) LCD screen. Even more importantly, it has a gyroscope on the lens as well as digital stability correction. Together these two features should more than compensate for my shakes. I don’t really need 12.1 megapixels, the 3.2 megapixels from the old camera being easily enough for my requirements. However, 12.1 megapixels is nice to have, the downside being that file sizes are much larger. The new camera didn’t come with memory sticks, so I had to purchase them separately. And because of the large file sizes, I had to buy much larger sticks than the ones I had been using with the old camera. Previously, I had used 256MB sticks but now I was getting 8GB and 16GB memory sticks, both Sony PRO Duo MagicGate Mark 2. However, when I got everything home, the 16GB stick wouldn’t work in the new camera. Instead, it was giving a “Cannot Access the Memory Stick” error and was instructing me to “Reinsert the Memory Stick”, with “Error C:13:01” also on the screen. The latter code indicates a formatting error so I tried reformatting it, initially with the camera and then on the computer using format y:/FS:FAT/A:8192 which also redefines the cluster size from 512B to 8kB. 60  Silicon Chip In both cases, it still would not work but when I put the memory stick from my old camera into the new camera, it worked fine. Adding to my frustration, the new memory sticks worked fine in the old camera and all the sticks worked fine when plugged into the USB ports of a computer. The 8Gb stick gave a different error message when plugged into the new camera. In this case, the error was “Memory stick may not record or play” but if you pressed OK on the camera, everything then worked fine. So go figure. Only chaos theory fits everything. JVC plasma TV A 127cm JVC VM/PD-Z50DX4 plas­ ma TV with a MultiMedia Box was brought in DOA (Dead On Arrival). Removing the covers revealed a complicated power supply roughly similar to the Toshiba 42WL58A described last month. The primary power supply generates +370V, +5V, +7V & +12V rails and these were all there. However, the +Vs (65V) and +Va (+185V) rails were absent. The sub power supply produced the standby +5V rail which feeds the Multi­ Media Box, which then feeds back to turn on the rest of the primary power supply. This control voltage was there. I was unable to obtain a circuit I was recently called out to service a 2005 LG 50PX4RA-TA 127cm plasma TV. The client complained that while she was watching, the set suddenly made a loud “pop” noise and then the picture went off. When I arrived, the set switched on OK from red LED to yellow to green and the sound was fine but, just as the client said, there was no picture. There was nothing for it but to take this large and rather heavy TV back to the workshop. After removing the 40,000 or so screws to get the rear cover off, I started measuring the supply voltages plus other voltages on the circuit but these were all there and within tolerance. What’s more, all the fuses were OK, the fans were working and none of the heatsinks became excessively hot, even after the set had been on for 30 minutes. This symptom and similar ones like dark pictures sometimes occur with the 104cm models and normally a replacement SUS-KIT (Y, Z and Control) fixes the problem. However, there are also a lot more clues like flashing red LEDs, blown fuses and missing or low voltages. In this case, none of these symptoms were noticeable and they don’t make a SUS-KIT for this model. In the end, a new Y-SUS and Z-SUS board fixed the problem. These boards are completely different from those in the smaller size LG plasmas. What’s wrong with Newcastle? The following story on car electronics comes from one of our readers, J. E. of Canberra. I’ll let him tell it in his own words . . . This story is about a weird electronic fault in a 1990 Volvo 940 GLE. The speedometer appeared to be allergic to Newcastle, NSW, in that it would fail a short time after getting to Newcastle and then start working again soon after returning home to Canberra. Unfortunately, the fault also affected the cruise control because the siliconchip.com.au cruise control receives its input from the speedometer. In operation, the speedometer receives its input signal from an inductive pick-up in the differential. After some investigation, a mechanic found that the cable between the differential and the car body was intermittent. Unfortunately, fixing this did not fix the problem. The genuine Volvo workshop manual costs around $500. However, I was able to get copies of a few diagrams of the dashboard, so I decided to investigate the problem myself. The first task was to check the signal at the input to the dashboard using a voltmeter (sitting an oscilloscope in the car was just not practical). This confirmed that the incoming signal was always present, so that seemed to eliminate anything outside the dashboard. The speedometer is mounted on the dashboard backplane and the only component related to the speedometer is a resistor (presumably to provide current to the inductive pick-up in the differential). This resistor measured correctly which suggested that the problem must be in the speedometer itself. The speedometer uses two PC boards, each about the diameter of the speedometer dial and mounted behind it. Now, I have had significant electronics experience but that was a long time ago and the lack of serviceability of the unit combined with its $1000 new price-tag scared me (my hands are not as steady as they used to be and my eyesight has deteriorated). Unfortunately, the professional “speedometer fixers” didn’t want anything to do with an electronic speedometer. However, I was able to find a local electronics service centre that does quite a bit of work fixing ABS electronics. Even better, the owner also had a Volvo 940 GLE with the same problem, so he was particularly interested in fixing my problem because it would give him the solution to his. He soon found that a number of electrolytic capacitors on the PC boards were faulty and replacing them fixed the problem. In fact, they had leaked and it appears that the residue is hygroscopic and conducts when not entirely dry. Newcastle is on the coast and I assume that the humidity got into the residue and shunted the signal, causing the speedometer to fail. Conversely, in Canberra the residue presumably dries off, the signal in no longer SC shunted and the speedometer works again. siliconchip.com.au Professionally Designed and engineered in Australia using Peerless speakers which are known and respected across the globe. Remarkable Cross-over design, built using the highest grade components designed to give maximum clarity and responsiveness for voice and tonal reproduction. For More Info Please visit: www.wagner.net.au/speakers www.d-s-t.com.au/speakerkits We stock everything you need for your Audio Visual installation including HDMI & RCA Interconnect, Plasma / LCD TV Wall Brackets, Speaker cabling, Plugs & Connectors, Tools and Soldering Equipment, Plus Lots More!! View our Catalogue online. Visit Us Online: www.wagner.net.au Email: sales<at>wagner.net.au September 2009  61 Phone: 02 9798 9233 138 Liverpool Road, Ashfeild, NSW, 2131 PRODUCT SHOWCASE Not just pretty . . . pretty smart! We’ve received a range of small PC boards from SchmartBoard which are claimed to make applications involving SMD chips almost child’s play. The patent-pending technology of SchmartBoards has the solder mask higher than the solder pads, which allows the chips to be easily held in place as their legs are in the grooves. Along with a general-purpose SMD Schmartboard (bottom right) and a general-purpose 0.8mm pitch thru-hole board (bottom left, with wires) the photo at right also shows Schmartboard’s Power Module board (left), Parallax Propellor Board (blue), 8-bit PIC Development Board (black) and RS-232 Module (red). Neither of the microcontroller boards have the microcontroller chip (you choose the one you want); similarly the power supply module is waiting for the appropriate 78xx regulator. Like many products these days, information packed with the modules is relatively scant but URLs direct you to the relevant pages of the Schmart- board website where you should find everything you need to know . . . and much more! Contact: Schmartboard Connections 131 Palm Beach Drive, Patterson Lakes, 3197 Tel: (03) 9017 3194 Website: www.schmartboard.com.au Thermal-imaging camera priced as everyday tool Emona Instruments has launched the Dali TE thermal imaging camera. For the first time thermal imaging cameras can be regarded as an everyday tool rather than a high priced instrument with limited use by consultants and specialist engineers. The Dali TE has a 160 x 120 resolution thermal imaging camera with a temperature range of -20°C to +250°C and laser pointer. It is ideal as a service tool for everyday electrical, industrial and HVAC applications and is priced to allow every technician to have one in their toolbox. The TE offers a number of measurement modes, including moveable sport, moveable area (maximum, minimum and average), Isotherm and alarm function. It also provides a choice of three palettes. Emissivity is variable from 0.01 to 1.0 or can be selected from a pre-defined materials list. Around 100 images complete with measure- ment data, can be stored on the built-in flash memory and are downloaded to PC via USB. The thermal images are saved as 14-bit radiometric jpegs. Battery life is three hours and the unit is supplied with two Li-Ion rechargeable battery modules and intelligent fast charger. The TE is supplied with “Dali Infrared Contact: Reporter” software, a Emona Instruments full function reporting PO Box 15, Camperdown NSW 1450 and analysis software Tel: (02) 9519 3933 Fax: (02) 9550 1378 Website: www.emona.com.au package. Av-comm’s “Pacific Satellite News” If you want to keep up with the very latest satellite news and information in this part of the world, you’ll find no better source that the monthly newsletter, “Pacific Satellite News”. It’s prepared and distributed by AvComm Pty Ltd whose principal, Garry Cratt, is regarded as one of Australia’s leading exponents in the field. It contains news on free-to-air and pay TV services, satellite launches and delays, industry snippets and most importantly, up-to-date satellite program listings with 62  Silicon Chip the data you need to watch them! There are also adverts from several satellite reception equipment suppliers. They also offer a library of back issues on CD. For more information, to arrange a subscription or even to get a FREE sample back-issue, contact Av-Comm direct. Contact: Av-Comm Pty Ltd 24/9 Powells Road, Brookvale NSW 2100 Tel: (02) 9939 4377 Fax: (02) 9939 4376 Website: www.avcomm.com.au siliconchip.com.au Cleverscope high speed charting Cleverscopes’ new charting module for the CS328A Oscilloscope Cleverscope adds 1 Mega Samples/s charting function. It streams captured signals to the hard drive at up to 1 Mega Samples/s until the hard drive is full. Powerful compression techniques make for snappy viewing of the signal which may be up to hundreds of Giga samples in length. Using a moving average filter, the 100MS/s captured signal is compressed down to the range 1 S/s to 1 MS/s with better than 14-bit ENOB, yielding unsurpassed dynamic range at this storage rate. Navigating the captured signal is fast and easy. The zoomed Tracking graph follows the Scope graph tracer to see the big picture and the detail simultaneously. Contact: Cleverscope 28 Ranfurly Rd, Epsom, Auckland NZ Tel: (649) 524 7456 Fax: (649) 524 7457 Website: www.cleverscope.com New Fluke RLD2 UV leak detector flashlight uncovers leaks instantly Designed for use by HVAC, plant maintenance and automotive technicians, using the new RLD2 UV leak detector flashlight technicians can uncover refrigerant leaks instantly, then use the laser pointer to pinpoint the exact leak location. With 100,000 hours of LED flashlight life and four operating modes, this versatile leak detector is a must-have for HVAC and A/C technicians. The detector has four modes for all flashlight and leak detecting needs, six bright UV/blue LEDs, which highlight leak detection dyes, so leaks are found quickly and easily plus a laser pointer that clearly locates the centre of the UV/blue field to pinpoint Contact: leak location. Fluke Australia Pty Ltd It also incorporates a bright Unit 26, 7 Anella Ave, Castle Hill, 2154 3-LED flashlight with a lock fea- Tel: (02) 8850 3333 Fax: (02)-8850-3300 ture, to hold on the flashlight beam Website: www.fluke.com.au Basslink commences telecoms link service Basslink, the high voltage DC interconnect between Tasmania and the mainland (see SILICON CHIP, Sept 08), has launched the Basslink Telecoms business. For the first time, Tasmanians – through their ISPs – will be able to choose a provider to carry high bandwidth telecommunications across the fibre link between Tasmania and the mainland. The new network brings infrastructure-based competition in backhaul to Tasmanian businesses and households, giving much greater access to high capacity broadband services. siliconchip.com.au New PIC18F/LF1XK22 with nW XLP Microchip Technology Inc has announced a new family of 8-bit PIC microcontrollers featuring nan o Wa t t X L P Technology, which enables extremely low sleep currents. The high-performance, low-power PIC18F13K22, PIC18LF13K22, PIC18F14K22 and PIC18LF14K22 (PIC18F1XK22) MCUs are available in 20-pin packages and provide 1.8 to 5.5V operation, with up to 16Kbytes Flash program memory. The devices feature an enhanced peripheral set that includes support for mTouch capacitive touch sensing and are well suited for a variety of generalpurpose applications. nanoWatt XLP Technology allows the PIC18LF1XK22 MCUs to operate longer using less power, or with fewer battery changes, by enabling sleep current of 34nA, typical at 1.8V; Timer1 oscillator currents of 800nA, typical at 1.8v, 32kHz and Watchdog Timer currents of 300nA, typical at 1.8V. Most low-power applications require one or more of these features and nanoWatt XLP Technology combines all of them into one device in the “LF” versions of the PIC18F1XK22 family. Contact: Microchip Technology Australia PO Box 260, Epping, NSW 1710. Tel:(02) 9868 6733 Fax:(02) 9868 6755 Website: www.microchip.com/xlp Billion’s Gigabit switch beats network blockages Network specialist Billion has released a $99 8-port Gigabit (Gb) switch to meet the increasing need for high-speed performance from home networks. While switches are often neglected as pedestrian plumbing for a computer network, no one disputes the benefit of top quality plumbing when their toilet gets blocked! The Billion BiPAC GS08 is a low-cost, high-performance switch which handles wired connections through its eight 1Gb Ethernet ports. It avoids network blockages caused by gamers on the PS/3 or X-Box 360 competing the TiVo downloading movies or parents trying to do their Internet banking. The Billion BiPAC GS08 uses a non-blocking architecture that supports every switch port at fullduplex capacity, backing all eight ports with Contact: a 16Gbps backbone link. The unit also has PC Range integrated Smart Power Saving technology 19 Aldenhoven Rd, Lonsdale, SA 5160 that enables your network to save power by Tel: (08) 8186 1800 Fax: (08) 8186 0222 as much as 60%, saving both power and Website: www.pcrange.com.au SC money. September 2009  63 Here’s a FREE graphics program to make your PICAXE Electronic Bread Board Layout Emulator Imagine being able to produce a professional quality diagram such as the one shown above to show how a circuit was laid out on a breadboard. You can – and the software to do it is FREE! And despite the name, it’s not limited to PICAXE circuits, it’s universal! W e shouldn’t have to tell you how incredibly ver- but to make it nice and simple for anyone else (magazine satile breadboards (also known as “Protoboards” editors included!) to understand. are when it comes to designing, developing and Professionals are one thing but newcomers hesitantly troubleshooting electronics circuits. following circuits “paint by number” style may especially We often use them here at SILICON CHIP when developing benefit from lucid layouts. projects for the magazine and we encourage readers of all Typically these will be students learning about practical levels to use these quite cheap and widely-available aids. electronics (often under tight syllabus and time constraints), But what if your design doesn’t quite work as intended when very clear circuit layouts may be appreciated as a and you start looking for help – perhaps on-line. confidence booster. You’re going to need to transfer the design onto paper, In spite of today’s ease of digital imaging, pictorial reor at least into a format that someone else can easily read quests may however meet with some reluctance, perhaps and hopefully trouble-shoot. due to the untidy nature of hook-up wiring. Well – let’s Or perhaps it does work exactly as you’d hoped and you face it – often it IS messy! want to share your brilliant design with the world (maybe Even some old hands are wary about posting public even get it published in photos of their new super SILICON CHIP?) It’s essenOriginal “Virtual Breadboard” software: Ray Wilson duper layout, as they tial that a clear, lucid repfeel the wiring may be resentation is presented, PEBBLE development and article author: Wayne Geary scorned. Additional material: Stan Swan and Ross Tester not only to avoid errors At least one’s soldering 64  Silicon Chip siliconchip.com.au breadboarding easy . . . will not be criticised with solder-less breadboards! Although long established for versatile and rapid prototyping, these breadboards still take time to populate, with associated wire stripping and neat component layouts requiring a focused mind and steady hand. When wrangling components under pressure, perhaps as a stressed teacher organising course work or a student Going way back, meeting project deadlines, confusing this is a valve “crystal set” radio receiver. Many, many “rat’s nest” layouts may result. millions of radio and electronics Well, now there’s a way to produce enthusiasts have “cut their teeth” breadsuperb breadboard layouts in just a few boarding circuits just like this one or more recently, minutes – thanks to new JavaScript- with diode-based crystal sets! based software known as PEBBLE (PICAXE Electronic Bread Board Layout Emulator). This totally free program has appeal for newcom- and straighten the leads. A 1964 patent describes a wooden ers, old hands in the electronics field and even (or perhaps plate breadboard with mounted springs and other facilities. especially?) school electronic courses. Some early commercial electronic kit “boards” had a While the title includes the word “PICAXE”, it is stressed cardboard or plastic base with a series of springs arranged that the program is equally useful in general and digital in a matrix and the component leads were slid between electronic fields. Besides, “PEBBLE” has a much better ring the turns of the springs to secure them mechanically and to it than does “EBBLE”! electrically. These were still readily available in the 1980s There’s something compulsive about a neat looking and 90s; indeed it is still possible to buy such things today breadboard circuit that makes you want to go and build it. as part of multi-circuit electronics project kits. Compared with gathering the tools to wrestle with a lashed All this brings us to today’s classic, usually white or up soldered version, a lucid “birds eye view” breadboard bone-coloured plastic pluggable breadboard, as illustrated layout tends to encourage even the most hesitant assem- in this article. It was designed by Ronald J Portugal of EI blers. Instruments Inc. in 1971. The author purchased his first breadboard of this type in the late 1970’s having 30 rows Breadboards and their advantages of two groups of five holes and two rows of holes along “Breadboards” got their name from the way electron- each side for power rails. ics circuits were often lashed together on a piece of scrap The breadboard has a matrix of holes in the top, one tenth softwood, sometimes using small brass nails hammered of an inch apart (most multi-pin components are based on into the board as anchor/solder points. the Imperial measurement). Inside there are sprung metal Occasionally, beginners misunderstood the term and strips which electrically link groups of holes together in actually pinched mum’s good breadboard to hammer nails a known pattern. into and connect components – with predictable (and often When a component lead is pushed into one of the holes painful!) results. it slides between the copper fingers at each side of the hole Some early breadboards in the days of vacuum tube cir- which makes electrical contact. When a second component cuits (valves) used point-to-point wiring and later circuits lead is pushed into another hole in the same group then used tag strips mounted to the board, onto which compo- the two component leads make electrical contact. A typinents were soldered to the various tags. cally breadboard has one or two rows of holes down each Other examples had an insulating sheet with a series side that are generally used for the power supply rails. of tags or pins along the two long sides between which Between these two sets of power supply rails are rows components were soldered. of holes, normally arranged as two groups of five with a The downside of these early breadboards was that the re- central gap. The gap is two holes wide and suits most of use of components could be difficult due to need to desolder the DIP integrated circuits. As discussed in this article, here’s a five-way tagstrip . . . siliconchip.com.au . . . and two types of tagboards. All three of these were very popular methods of construction before PC boards became the more preferred method. September 2009  65 Again, back in the pre-PC board days, construction methods were usually either point-to-point (ie, from component to component where possible) but also involved the use of tagstrips to also mount components on. One prime advantage of the breadboard is that no soldering is required, which removes the safety risk (eg, of burns). Other advantages are that components can quickly be changed for circuit adjustment, there is no damage from soldering and desoldering so that components can be re-used many times over and time to develop or change a circuit is faster than a soldered board. As such, a circuit can be constructed and tested quickly to prove operation before moving to more permanent prototyping boards and ultimately designing and assembling final project circuits on custom-designed printed circuit boards. For these reasons, many hobbyists, electronics labs and in particular schools make use of breadboards. In the school environment, safety with hot soldering irons and the short time available to perform an electronics lab session make the use of breadboards virtually paramount. What is (and is not!) PEBBLE? PEBBLE is a software program that gives a visual or pictorial simulation of a circuit layout on a protoboard. It does not design the circuit for you, nor does it show any errors you have made. If, for example, you connect the battery the wrong way around and your errors are copied by those who then build the circuit, the smoke will escape just the same! It enables the user to show the layout of a circuit being assembled on a breadboard or protoboard. The visual representation includes the wiring and a range of discrete electronic components, integrated circuits and even a range of off-board components. It was originally intended as an aid to producing PICAXE circuits, therefore PEBBLE features an extensive range of PICAXE chips and many of the more frequent support chips, all of which have the pin designations shown against each pin. But it’s grown into much more than a PICAXE aid. It’s now universal and can be used with virtually any breadboard/ protoboard circuit. There is a range of general-purpose DIP format IC chip layouts for those occasions when the chip Above is the opening screen of PEBBLE. The 23-way board is the default but you can change it as you wish. At right is the component menu – just drag and drop those required. 66  Silicon Chip siliconchip.com.au you are working with is not Included is a range of comincluded in the default packponents suited to the PICAXE age library of components. microcontroller community. PEBBLE does not incorAfter some months of hard porate any animation. If you work including a number of must have animation, there preliminary releases for othare several commercially ers to trial, Version 2.2 was available packages which released. incorporate animation and Now in version 2.4 (even if operational emulation. our screen shots show 2.3!), it Commercial programs inincorporates some recommenclude PICAXE VSM by Rev dations from members of the Ed for £50, Yenka ElectronPICAXE community includics by Yenka.com (Crocodile ing well respected educator technology) at $825 for a small and frequent S ILICON C HIP school site license), Virtual contributor Stan Swan. Breadboard by Virtualbread- Here’s how the component holes are connected together The original package ocboard.com, and the National internally in a typical breadboard/protoboard. Others may cupied 354 Kbytes of disk Instruments Multisim “Elec- only have one supply rail top and bottom. space and contained a total tronic Workbench” for $909 of 54 files. The program infor a single user for 1 year or corporated a single 23 row $27225 for a college license. Some of these commercial breadboard as a working “surface” with single orientation products may have a free limited version available for general 8, 14 and 16-pin DIP IC packages, a single size of trial purposes. resistor, a single type of capacitor, a single colour horizontal PEBBLE is not a trial – for your money ($0.00) you get format only LED, a single size and type diode package, and the complete working version. Schools will be lining up wires that could only be aligned to the breadboard holes. for this one! While Ray Wilson has subsequently incorporated some of the changes started by the Author (for example 38-row Origins of PEBBLE bread boards) and a few of the simple suggestions put forA US audio enthusiast by the name of Ray Wilson cre- ward by PICAXE community members, Ray, being primarily ated a program called Virtual Breadboard to aid him and analog-oriented was happy to leave development into the his followers in the analog and audio fields. This program digital and PICAXE realms to an enthusiast in that field. had a rather limited repertoire of components and wires. PEBBLE at Version 2.4 occupies 3.6MB of disk space and Earlier this year, the author contacted Ray Wilson for contains a total of 461 files. permission to take the core from the Virtual Breadboard What PEBBLE includes program and create a program package aimed at the general and digital electronics enthusiast. PEBBLE has an extensive repertoire of components, Dragging the DIP IC image to the breadboard, then (right click) editing to insert label text and selecting the “Picaxe 14M” to display the IC with pin identification” siliconchip.com.au Composite image showing the editing features for various types of light emitting diodes (at the left) and signal/power diodes (at the right). September 2009  67 including: • approximately 40 breadboard permutations, • numerous DIP integrated circuits in 8 pin sizes, • resistors in four physical sizes, • capacitors in four types with each in three sizes, • LEDs in five colours and four orientations, • diodes in two packages with three sizes, • transistors in two package formats and four orientations. • terminal strips in various formats including some generic SIL plug-in modules which use terminals strips, • four switch formats, • and extensive range of other components including LDR’s, thermistors, resonators, piezo sounders, potentiometers, trimpots, LCD modules, various battery combinations, keypads, relays and assorted motors including a servo-motor. Breadboards Breadboards are provided in 23, 30, 38, 44 and 50-hole lengths. In addition to the ubiquitous white breadboard there are several in alternative colours such as some light blue variants which provide better contrast for many components. There are boards available in formats with single and dual power rail per side. One breadboard variant is based upon the complete DSE H-6505 prototyping board, a second is based on the DSE H-6513 fibreglass prototyping board while a third is based upon the Kiwi Patch Board (KPB). While not exactly a breadboard in the visible sense, there is a separate off-board area provided below the displayed breadboard with a similar but invisible, hole spacing for the positioning of typical related breadboard components such as toggle switches, LCD modules, motors and batteries. The invisible hole spacings are the same as the visible breadboard area. There is also a specialised version of a 23-row white breadboard with coloured polarity indication for the power Flexible wire editing allows colour selection, wire positioning and compact grouping with the offset wire feature. 68  Silicon Chip rails, a small off-board patch area at the right end having visible holes/connections points and a pre-wired battery box (including three AA cells) for a quick-start format for learners and school applications where time in getting newcomers under way is critical. DIP IC packages From the humble beginnings for DIP IC packages with just a single orientation in 8, 14 and 16 pins, PEBBLE has an extensive range providing 27 DIP packages. These include 4, 6, 8, 14, 16, 18, 20, 22, 24, 28 and 40pin formats and can be orientated with pin 1 to the bottom left or the top right. Each size is available as a general DIP package for use when a specific IC is not available. A full range of PICAXE chips in the 8 to 40-pin range is provided. The ubiquitous 555 timer IC is also included. Frequent support chips such as RTC’s (DS1307 and similar), EEPROM (24LC series), i2c Expanders (MCP23017), Darlington transistor packages (ULN2803), H-driver package (L293D), various other packages such as the 74HC595 shift register and 4000 series IC’s for counters and BCD to 7-segment drivers. Finally there is a typical 7-segment display (FND500 series). Discrete components: Resistors are available in four physical sizes and two orientations (horizontal and vertical). The colour bands on the resistors are active and change to reflect the selected resistance value. Capacitors are provided in polyester “greencap”, radial and single-ended electrolytics and tantalum packages. Capacitors can be oriented in four directions to account for polarity and three sizes for each package. Capacitance value can be included as a notation displayed across the body of the component image. Diodes are provided in both glass (orange colour) and plastic (black colour), each in four orientations to account A large range of breadboards/protoboards are available from the selector below the component menu. siliconchip.com.au for diode polarity. The text colour for diode type notation/ labelling realistically reflects the typical colours on these diode packages. LEDs are available in five colours and four orientations. Terminal strips are available in a number of different formats including header sockets and header pins and screw type. General terminal strips come in lengths from 2 to 9 terminals/pins per strip. Longer presentations can be provided by placing shorter strips end to end. Under the terminal category are included some specialised items which includes a series of Single-In-Line (SIL) modules with from two to nine terminals, a typical mini stereo socket as used for PICAXE micro-controller programming and the RevEd AXE029 modules intended for plugging onto a breadboard for ease of programming. One can of course still lay out a PICAXE programming circuit on the breadboard using the standard 10k and 22k resistors. Miscellaneous components currently include some 12 device types including LDR, thermistor, clock crystal, resonator, potentiometers and trimpots (both in two orientations), batteries in eight formats from two to four AA cells a 9V battery and a CR3032 3V Lithium cell, 2x16 character LCD modules with serial, i2c and parallel connections, two sizes of keypads, two relay images and several motors: DC, uni-polar and bi-polar steppers plus a servo motor. Switches are provided in four basic packages being SP momentary push button, SPST toggle, SPDT toggle and DIP switch. The pushbutton and toggle switches are provided in four orientations. DIP switches are available as a hexadecimal rotary 6-pin package and from two to nine switches in a single DIP package. the resistor colour code) and with horizontal and vertical orientations aligning with the breadboard holes. Selections now available include: • wire ends to be bare (for insertion into a hole) or insulated for continuation in a new direction; • the body of the wire to be offset vertically and horizontally from the breadboard holes by one-third of a row so two wires can be run between the rows of holes: • wire ends that start and end straight or turned left/up or down/right; • wire end alignment to three positions as left/up from hole lines, on the hole lines, or right/down from hole lines. Note tabs Small one and three-line note tabs are available, akin to post-it note strips, that can have some (short) text on them as indicators or for information. Note tabs are not restricted to alignment with holes and can be placed anywhere on the screen. Memory/screen resolution Wires are an area where extensive permutations have been incorporated. The original scheme started with wires available in ten colours (as black, brown, red, orange etc akin to PEBBLE version 2.4 is a 3.6MB package comprising an HTML program front end and a series of JavaScript files with various functions for the internal applications and utilities which make up PEBBLE and finally a library of component images. The bulk of the memory required is taken up by the component library. PEBBLE runs under a JavaScript-enabled browser. It has been tested by the Author with Internet Explorer 7 and Mozilla Firefox 3.0.11. PEBBLE may function with other web browsers but has not been tested by the author. Note that the browser must allow JavaScripts to operate. (Editor’s note: we can also confirm it runs perfectly on Google Chrome!). Ideally, the screen resolution should be at least 1280 x 1024. The following provides a guide on what can be achieved/seen with various screen resolutions. A minimal PICAXE 08M circuit to allow programming and operation on the breadboard with battery supply. The circuit matches the insert schematic from the PICAXE manual. Adding a pushbutton switch (digital input) and potentiometer (analog input) to the PICAXE circuit in the image at the left. Breadboard wiring siliconchip.com.au September 2009  69 breadboard is fully visible and the breadboard plus the entire off-board component area is also visible without scrolling once the titles at the top of the screen are scrolled out of the way. For longer breadboards, a screen resolution width of 1440 pixels is required for a 44-row breadboard and a width of 1600 pixels is required for a 50-row breadboard without the need to scroll horizontally. Using PEBBLE Just imagine trying to draw out this rats-nest in the conventional way: the likelihood of errors is enormous! However, with PEBBLE, it’s just a matter of moving methodically across the protoboard and reading component positions, then dragging PEBBLE components into the same places on the virtual protoboard. Repeat for all the links and you have a diagram that’s not only easy to follow, it’s repeatable – and it also makes troubleshooting that much easier! At a resolution of 1024 x 768 the screen width is adequate for a standard 23-row breadboard (but not the stretched 23-row Learners Board). The entire breadboard is visible but it will be necessary to scroll down to see the off-board component area and some selectors/buttons at the bottom of the component menu. With a 30-row breadboard, all of the holes are visible but not the right hand border/edge of the board without scrolling horizontally. With a screen resolution of 1280 x 1024, up to a 38-row Expanding the circuit by adding three LEDs as output indicators to the PICAXE circuit. 70  Silicon Chip To start PEBBLE, simply double-click on the PEBBLE. html file within the directory (folder) where you have stored the program package. A desktop shortcut can be created right clicking the PEBBLE html “program” file and selecting create shortcut. Then drag or copy this shortcut onto the desktop for a quick start. Once the program is started, the user is presented with a component menu down the left side of the screen, an empty 23-column breadboard, SAVE/LOAD buttons below the menu together with a breadboard selector. When the breadboard selector is clicked upon, a full list giving all the breadboard permutations is given. Select the desired board type and the displayed board changes instantly without affecting any components already on the board. Components are placed by left clicking the icon on the component menu or dragging to the breadboard. Once on the bread board the component can be further repositioned. Right clicking on a component or wire initiates a component specific pop-up window with various editing options including the ability the copy or delete the component. The pop-up window for many component types has a text input box at the top in which the user can place text for the component label. Remove the default text if no label is desired. The component specific pop-up edit windows allow defining a title/label, selection of package type/size, ori- Click the Save/Load button displays a window with the data for the circuit in the image at the left. Cut and paste to a text editor to save for the future. siliconchip.com.au entation for many discrete components. Once the user becomes proficient in the use of the wire editing window, a wire can be routed to virtually any point on the board in whatever shape or path the user desired. Below the left side component selection menu are two buttons. The right side button labelled “Clear all” does just that. There is the usual “Are you sure?” type pop-up confirmation window in case of an accidental click. Click the “Okay” button in the confirmation window and the breadboard is instantly cleared. The left side button labelled “Save/Load” provides a new window. When clicked the component data for all items including wires on the breadboard is displayed in a list. You can copy and paste this data into a text file, using for example MS Notepad, for saving and future use. To reload a previous design, copy the component data from the saved text file into the window and click to “Load Circuit” button. You are asked to confirm that you wish to delete all existing components, then the new circuit is loaded and immediately displayed. This text file method can also be used to transfer breadboard circuit designs/ layouts with others. To obtain a hard copy of the visual presentation, just press the “Print Scrn” button on your keyboard. Then, using an image editing program such as Photoshop, MS Paint or PaintShop Pro, paste (Ctrl-V) the data into your image editing program of choice. From there you can clip the desired portion and save the image in whatever image format you desire (from those that your paint program provides). So with PEBBLE loaded onto your computer, never again siliconchip.com.au should there be embarrassment over providing an image of what your latest and greatest breadboard project looks like. You will need to ensure that you unzip using the directory structure so that the various file type are placed in the correct sub directories. The package can be placed on any drive or even a memory stick and the main directory name can be changed but the sub directories must remain as defined in the zip file. Accessing PEBBLE PEBBLE V2.4 can be used in either of two ways. Firstly, some sites are hosting PEBBLE in an on-line format so that users can use PEBBLE direct from the internet without having to download a zip file and uncompress the file to store the program on your hard drive. Sites that are providing this form of access to PEBBLE include: www.rev-ed.co.uk/picaxe/pebble www.gadgetgangster.com/toolbox www.picaxe.orconhosting.net.nz/pebble24a Alternatively, some websites will provide the PEBBLE program as a zip file that can be downloaded, uncompressed and stored onto your hard drive, which will enable use of PEBBLE without access to the internet in future. Note that the computer must still have a javascript enabled browser installed to use PEBBLE. www.rev-ed.co.uk/software/pebble.zip www.minisumo.org.uk/pebblev 2_4a.zip SC September 2009  71 And now for something completely different similar! Putting PEBBLE to work! Mount a Seismograph on a Protoboard, PEBBLE it then transfer it to a KPB. What’s a KPB? Read on! by Stan Swan A powerful 7.8 magnitude earthquake – the biggest experienced in the Shaky Isles for 80 years – occurred in southern New Zealand during the early evening of July 15th last. Had you owned a Seismograph, you might have known about it virtually straight away. The earthquake fortunately struck in a very remote part of the South Island (Dusky Sound-Fiordland) and damage was minor, with no injuries or deaths. Few Kiwis in the more populous North Island even felt it! However as a tribute to the massive power of the event, it transpires that this NZ region has been measurably twisted slightly out-of-shape. Once the shaking settled, the net result in that region has been a land raising of about a metre, along with a sideways shift westward approximating a handspan. Yes – NZ is now (fractionally!) closer to Australia. With memories of the Boxing Day 2004 magnitude 9.3 Indian Ocean tsunami still painfully fresh, Australian east coast alerts (and even some precautionary Lord Howe Island evacuations) promptly developed. Thankfully these concerns proved a false alarm, as only mere surges – no This map shows the locations of the Australian and Pacific Plates, with the site of the NZ July 15 earthquake, right at the junction of these plates. higher than normal ocean waves – eventuated trans-Tasman. However, closer to the quake source, waves of 1m high were experienced, and even in remote Hawaii handspanhigh rough water was noted. The event served as an excellent test run of the Australian Tsunami Warning System (ATWS) and as a reminder that devastating earth movements can strike at any time, with no warning. New Zealand sits above an area of the earth’s crust where the Pacific and Australian tectonic plates collide and earthquakes are a regular occurrence. Kiwis reckon lots of small quakes (to relieve pressure) are better than a single large rumble! The Dusky Sound quake was certainly no mere pebble splash however and it has triggered renewed interest in earthquake monitoring overall, perhaps even with an eye on the holy grail of eventual prediction. Seismograph We mentioned before a Seismograph which is, of course, a device used to The Kiwi Patch Board, a PC board which is has the same hole spacing as a 23-way Protoboard but has many extra features. It can be used to transfer protoboard layouts to PC boards. 72  Silicon Chip siliconchip.com.au both monitor and, with the right equipment, measure earth movements. Readers may recall the September 2005 SILICON CHIP Seimograph article by Dave Dobeson. This detected delicate earth movements and vibrations by pendulum displacement, with deviations optically monitored by a LED/LDR combination. These READADC values were then handled by an opamp and PICAXE-08M to yield a classic earthquake “squiggly line” seismic trace display. Dave’s design is still perfectly valid and motivated readers may already have nervously thumbed through dog eared SILICON CHIP magazines looking for details. But wait – here’s a fresh layout approach involving PEBBLE! Kiwi Patch Board Taking the breadboard/protoboard concept one step closer to permanency, a so-called “Kiwi Patch Board”(KPB) has now been developed which essentially allows the direct transfer of the classic 23 x 10 breadboard layout onto a PC board which has exactly the same hole pattern and spacing. The KPB is a quality fibreglass and silk-screened PC board measuring ~90mm x 45mm. It has many “extras” over the breadboard, including space for a 7805 regulator and smoothing capacitor (or other 3-pin regulator if you aren’t using a PICAXE), 3.5mm PICAXE programming socket, screw PEBBLE diagram of the Simple Seismograph (SILICON CHIP September 2005) control transferred to protoboard – but exactly the same layout can be used to populate a Kiwi Patch Board. There’s also room for the “extras” such as the voltage regulator, sensitivity pot, programming socket, etc. terminal, header pin and support mounts, dual supply and even extra rails under the IC. The KPB is now available in Australia from MicroZed and sells for $6.75. The approach involves doing initial circuitry development on a solderless breadboard,using PEBBLE as a layout refinement aid. The advantage of this technique is that components and links on the final working breadboard design can then be progressively swapped over and soldered onto a the KPB. Such “paint by number” style assembly can be very confidence REG1 7805 100 D1 1N4004 IN +5V OUT IN LED1 K boosting! Of course, this goes against traditional PC board design somewhat which call for as few links as possible – but being able to switch between breadboard and patch board with exactly the same appearance means much less likelihood of misteaks misstakes misst . . . errors. In fact mounted circuitry can look so professional that projects may not even progress to a dedicated PC board. Educational acceptance of the KPB has been very strong here in NZ. Kiwi educators, keen to both improve GND GND A   LDR1 OUT 100nF 10k K 470F 9V DC IN 470F CON1 SERIAL OUTPUT CON2 DB9F SENSITIVITY VR1 100k A 470F 25V 7805 VANE ON SEISMIC MASS 1 6 10k 2 7 3 IC1 741 4 6 VR2 5k 4 3.3k 1k 10k* (SEE TEXT) 3 Vdd P0 P1 P3 2 3 IC2 5 PICAXE P2 -08M SER 2 IN P4 Vss 5 22k 8 H L E 10k 7 3.3k 10k LED SC  2005 SIMPLE SEISMOGRAPH LOGGER OUTPUT 1N4004 A K K A The circuit diagram of the Simple Seismograph, reproduced from the September 2005 edition of SILICON CHIP. Refer to that issue for complete operational details and the seismic mass which drives it. siliconchip.com.au September 2009  73 JOIN THE TECHNOLOGY AGE NOW with PICAXE Developed as a teaching tool, the PICAXE is a low-cost “brain” for almost any project Easy to use and understand, professionals & hobbyists can be productive within minutes. Free software development system and low-cost in-circuit programming. Variety of hardware, project boards and kits to suit your application. Digital, analog, RS232, 1-Wire™, SPI and I2C. PC connectivity. Applications include: Datalogging Robotics Measurement & instruments Motor & lighting control Farming & agriculture Internet server Wireless links Colour sensing Fun games Ben, a 17 year old electronics student at Hutt Valley High School, Wellington, NZ, finds putting it all together is so simple when he has PEBBLE to guide him. presentation and ease the agony many electronics novices experience with circuit construction, were predictably behind the KPB design. PEBBLEing the Kiwi Patch Board Although PEBBLE is essentially intended for basic breadboards, it’s been satisying to also have the moreinvolved KPB layout available under this versatile emulator. PEBBLE’s save and load facility pleasingly also allows designs to be emailed or set up as templates. Given the intended PICAXE slant of the KPB, the two resistors and inverted 08M programming layout may especially suit the latter. To further ease the quest, some components (in particular the screw terminals, 7805, smoothing capacitor and programming socket) have been pre-mounted. If these are unwanted then a trimmed KPB board can be selected from PEBBLE’s offerings. KP-Boarding the Seismograph Distributed in Australia by Microzed Computers Pty Limited Phone 1300 735 420 Fax 1300 735 421 www.microzed.com.au 74  Silicon Chip Components in the original 2005 earthquake detector were shown soldered onto a dedicated PC board and run from an unregulated 9-15V supply. Programming can be via the 3.5mm socket but an input has also been provided to suit the header pin style used in many SILICON CHIP PICAXE articles. Component placement onto a KPB under PEBBLE was almost “paint by number” but the ability to juggle board layout proved very gratifying. Such “cut and try” versatility, normally requiring extensive pen and paper planning and tedious wire stripping, made for great productivity. The bonus of a large-screen board view furthermore eased eye strain. Aside from the supply rail red and ground black, most wire colours shown here are not sacred and were simply selected for functional clarity. Many alternative layouts are possible for this circuit but with a further ground rail assigned in the channel under the ICs, the eventual wiring became very clear and direct. Readers with a keen eye for such things are encouraged to relate to this new PEBBLE version to both the schematic and original layout. NZ’s well known tectonic tendencies, also manifested as significant volcanic and thermal activity, means comprehensive monitoring systems have long been warrented here. Both Civil Defence alerts and web based seismic services (www.geonet. org.nz) are well established, perhaps reducing the need for a personal seismometer within NZ. Coastal Australian readers of a nervous disposition however may already have their soldering iron out and warming up . . . Resources, credits and references are hosted at www.manuka.orcon.net. nz/seismo.htm SC siliconchip.com.au Autodim add-on for the 6-Digit GPS Clock By JIM ROWE Here’s a low-cost add-on for the Digital GPS Time Display published in the May & June 2009 issues of SILICON CHIP. It senses the ambient light level, so that a modified program running in the display unit’s PIC controller can adjust the LED brightness to a comfortable level – ranging from full brightness when the ambient light level is high down to dim when the ambient light is very low. S OON AFTER THE basic 6-Digit GPS Time Display was published in the May 2009 issue, we received emails from readers who were disappointed that we hadn’t provided the design with an “autodim” facility. And they wanted to know if such a feature could be added in. Unfortunately, trying to incorporate dimming on the existing clock PC board is quite difficult. The conventional way of doing it would be to use a transistor and LDR circuit to control the emitters of all six common-cathode siliconchip.com.au driver transistors, Q15-Q20. We have used this scheme on quite a few past projects which had a PIC micro and 7-segment LED displays but a quick look at the PC board pattern shows that it would be quite impractical. This presented a real dilemma un­ til we came up with an alternative scheme: use an LDR and transistor circuit to allow the PIC micro to directly monitor the ambient light level and then change the duty cycle of the multiplexed drive to the 7-segment displays. So we set out to develop the “Auto­ dim Display Sensor” described here. The hardware was the easy bit, of course – the firmware mods took a bit longer. How it works The new hardware consists of just a few parts on a small PC board. This mounts on 10mm spacers in front of the display unit’s main PC board, in place of the DB-9 connector (CON1) which was originally used to feed in the NMEA-0183 data stream from the September 2009  75 lower than the 2.2kΩ emitter/collector resistor. This makes it suitable for driving one of the analog-to-digital converter (ADC) inputs of the display’s PIC18F877A microcontroller (IC1). In this case, the sensor voltage is fed to the micro’s AN5 ADC input. And that’s really all there is to the hardware side of the add-on, apart from the 100nF capacitor across the 150kΩ resistor. This capacitor is used to filter the LDR’s output voltage, to remove any modulation from the indoor ambient lighting level. +5V ON MAIN BOARD 10k LDR1 (RP-3480)  B B C Q1 BC548 E Q2 BC558 C PIN 8 (AN5) OF IC1 (0V FOR VERY LOW AMBIENT, +4.5V FOR BRIGHT SUN) E 100nF 150k 2.2k GND ON MAIN BOARD BC548, BC558 SC 2009 AUTODIM DISPLAY SENSOR Modified firmware B E The modified firmware for the PIC regularly monitors the voltage applied to the AN5 input (pin 8). It does this by directing the ADC module inside the PIC to measure this voltage. It then tests the measured voltage level and varies the on-off ratio of the display digit switching signals to vary the apparent display brightness, over six levels. As a result, the apparent display brightness varies between virtually full brightness at high ambient light levels down to about 17% of full brightness at very low ambient levels. C Fig.1: the circuit uses an LDR to sense the ambient light level. The resulting DC voltage across the 150kΩ resistor is then buffered by complementary emitter follower stage Q1 & Q2 and fed to pin 8 of the microcontroller on the display board. TO PIN 8 OF IC1 (PIC) TO +5V LINE TO GND 1 9 0 8 0BC548 240 LDR1 2.2k 150k ERJ Q1 100nF +5V AN5 GND BC558 Q2 10k Building it Fig.2: install the parts on the PC board as shown here. Take care not to get the two transistors mixed up. GPS Frequency Reference. This DB-9 connector is no longer needed if you’re using the GPS receiver module described in the June 2009 issue. Fig.1 shows the circuit details. The ambient light level is sensed by LDR1, a small light-dependent resistor (LDR) which varies its resistance between about 2MΩ in the “dark” and a couple of hundred ohms in bright sunlight. This LDR is connected in series with a 150kΩ resistor across the +5V supply. As a result, resistance changes in the LDR result in corresponding DC voltage changes across the 150kΩ As mentioned earlier, the additional components are all mounted on a small PC board. This is coded 04208091 and measures just 36 x 19mm. Fig.2 shows the parts layout on the PC board. The only polarised parts are transistors Q1 and Q2, so make sure you fit these with the orientation shown. Also be careful not to swap the two: Q1 must be an NPN BC548, while Q2 is a PNP BC558. The LDR is not polarised and can be fitted either way around. Leave its leads about 15mm long so that they can be bent outwards from the PC board after it is fitted to the board. This allows the sensitive “front face” of the LDR to be turned away from the main LED displays when the add-on board is mounted in position. Note: if the LDR is able to pick resistor, the level varying from close to 0V when the ambient light level is very low up to about +4.5V in bright sunlight. Unity-gain buffer The other components in the circuit, based on transistors Q1 & Q2, make up a near-unity gain impedance step-down buffer. This ensures that the light-dependent output voltage is made available at a much lower impedance level than 150kΩ. In greater detail, transistors Q1 and Q2 form a complementary emitter follower, with a source resistance much Table 1: Resistor Colour Codes o o o o No.   1   1   1 76  Silicon Chip Value 150kΩ 10kΩ 2.2kΩ 4-Band Code (1%) brown green yellow brown brown black orange brown red red red brown 5-Band Code (1%) brown green black orange brown brown black black red brown red red black brown brown siliconchip.com.au IC1 PIC 16F877A (8) REG1 78L05 1 + + 4004 CON2 MAIN DISPLAY BOARD +5V AN5 GND AUTODIM ADD-ON BOARD 19080240 ERJ NOTE: FOR CLARITY, WIRES ARE SHOWN ABOVE MAIN BOARD. IN REALITY, THEY LOOP AROUND TO UNDERSIDE OF THIS BOARD Fig.3: only three leads are required to connect the autodim board. Note that the connections are actually run to the underside of the display board. up too much light from the displays themselves, the auto-dimming feature won’t work. Instead, the displays will run at full brightness, regardless of the ambient light level. Only three wires are required to connect the auto-dimming board to the main display board. Fig.3 shows the details. The first step is to solder three 80mm lengths of light-duty hookup wire to the three external wiring points (ie, +5V, AN5 & GND). That done, attach two M3 x 10mm tapped spacers to the underside of the add-on board, using two M3 x 6mm machine screws. The completed add-on assembly can now be mounted in the lower lefthand corner on the main display board. You will have to remove the display board from its case in order to do this. The add-on board is secured in place using two further M3 x 6mm screws which pass up through the upper pair of 3mm holes that were originally provided to secure the DB-9 connector (CON1) – see photos. The three leads from the add-on board can now be fed to the rear of the main board and connected to the Parts List 1 PC board, code 04208091, 36 x 19mm 2 M3 x 10mm tapped spacers 4 M3 x 6mm machine screws 1 light dependant resistor (LDR1) 3 80mm lengths of light-duty hookup wire Semiconductors 1 BC548 NPN transistor (Q1) 1 BC558 PNP transistor (Q2) Capacitors 1 100nF MKT metallised polyester Resistors (0.25W 1%) 1 150kΩ 1 2.2kΩ 1 10kΩ appropriate points underneath. As shown in Fig.3, the +5V lead goes to the +5V supply rail near the output pin of REG1, while the ground wire goes to the earth copper at what was originally pin 5 of CON1. The third centre wire (AN5) goes The autodim board is mounted on two M3 x 10mm tapped spacers. These are attached to the main board using the holes originally provided to secure the DB-9 connector. to pin 8 of the display’s PIC16F877A micro (IC1). This pin was not used in the original “non-dimming” version. Once these three connections have been made, you can slip the finished board assembly back into the enclosure and fasten it in place. All that now remains is to download the new version of the GPS Time Display firmware (0410509B.hex) from the SILICON CHIP website and reprogram the PIC micro so that it knows how to monitor the LDR voltage and vary the display brightness accordingly. Note that the add-on board by itself won’t give you the autodimming function unless you use the revised firmware in your PIC. The updated firmware now replaces the original program whether or not you have the add-on board. However, if you don’t have the add-on board, you must now connect pin 8 of IC1 to the adjacent +5V supply rail via a 2.2kΩ resistor. This is necessary to give the PIC’s AN5 input a de-facto “bright sun” input voltage level in the absence of the LDR sensor board. That’s it! With the add-on LDR sensor board and the modified firmware running inside the PIC, your GPS Time Display will now be able to adjust its brightness according to the ambient SC light level. Issues Getting Dog-Eared? Keep your copies safe with these handy binders. REAL VALUE AT $14.95 PLUS P & P Available Aust, only. Price: $A14.95 plus $10.00 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. siliconchip.com.au September 2009  77 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ A Deluxe 3-channel UHF Rolling Code Remote Control Part 2 – by John Clarke Last month we introduced our new high security remote control and got as far as completing both the receiver/relay driver and transmitter. This month we’ll put it all together and get the two parts talking to each other – securely! W e’re assuming that you’ve completed construction, including setting the transmitter and receiver identities, as detailed last month. You will also have given both PC boards a visual check and made sure that there are no solder bridges (except the deliberate ones in the transmitter identity!) or breaks, bad joins or errors. Testing With IC1 out of its socket, connect a 12V plugpack or other 12V supply via the power socket. Check that LED5 lights and that there is about 5V between pins 5 and 14 of the IC1 socket. The voltage could range from 4.85 to 5.15V. If this is correct, switch off power and plug in IC1. Place the LK1 jumper in the “out” position and rotate VR1, VR2 and VR3 fully anticlockwise to set the momentary period at minimum. Apply power and press S1, S2 and S3. This should activate RELAY1, RELAY2 and RELAY3 for about a quarter of a second each with LED1, LED2 and LED3 lighting up during this period. If this test is OK, you can assume the circuit is working correctly. Now it’s time to set the operation of the relays. Momentary or Toggle Note that while we have made two of the relay “NC” connections available, these may not be of much use in the momentary mode. However, they could be quite useful in the toggle mode. Setting the relays for momentary or toggle mode is done in this way. 82  Silicon Chip We presented construction details for the two PC boards last month. Here’s what our completed project looks like. The panel on the receiver is actually an overhead projector transparency glued to the inside of the lid, so you can see the LEDs inside the case. siliconchip.com.au 135 54 B A 20 15 (SIDE OF BOX) ALL DIMENSIONS IN MILLIMETRES (END OF BOX) 22 B 22 B B Fig.6: drilling details for the specified polycarbonate box. The “B” holes are for the output wiring cable glands while the “A” hole is for the DC input socket. 14 CL Place the LK1 jumper in the ‘in’ position. Set BCD1 switch to the number of the relay that you wish to change operation. Then press S2 momentarily. (Do not press S1 or you will lockout the transmitter with the identity number that is set on BCD1 instead). For example, if you want RELAY1 to be changed from momentary to toggle operation, set BCD1 to position 1. Then press S2. Now you can place the LK1 jumper in the out position and by pressing S1 you will have RELAY1 operating in the toggle mode. To revert to momentary mode, place LK1 in the ‘in’ position, set BCD1 to ‘1’ and press S2 again. Placing LK1 in the out position and pressing S1 will show that RELAY1 now operates in momentary mode. Momentary period Momentary period for each of the relays is set with its associated trimpot (ie, RELAY 1 is set by VR1; RELAY2 by VR2 and RELAY3 by VR3. Periods are adjustable from 0.26s to 2s in 0.26s steps, then in 1s steps to 10s and in 15s steps to 4.4minutes. Table 1 shows a sample of the settings available and the approximate voltage that is measured at the trimpot test points for various timeouts. The voltages can be measured between TP GND and the appropriate test point (TP1, 2 or 3) for VR1, VR2 and VR3 respectively. If you want only short timeouts, it is easier to simply experiment with the position of the trimpot for the desired timeout. For longer timeouts you will save time in finding the right setting for the trimpot by measuring the voltage and comparing this to the timeouts from Table. 1. Note that the minimum period of 0.26s will be set for the first 10-20° of trimpot movement clockwise from its fully anticlockwise point. This is done so that it will be possible to finely set the increments of 0.26s at the lower end of travel. Trimpots tend to jump in value at their travel extremes and having this dead band of operation moves any changes in time settings into the more linear section of the trimpot. At this stage if the transmitter identity is ‘0’, pressing the switches on the transmitter should activate the relays on the siliconchip.com.au HOLE A: 10mm DIAMETER HOLES B: 12mm DIAMETER receiver. This is only if you have not used the randomise function on the transmitter. Also the transmitter needs to be at least 1m from the receiver to work correctly – any closer may overload it. If you have activated the randomise function on the transmitter, then you will need to register the transmitter. See the registering section. Randomising Randomisation of the transmitter ensures that it uses a unique set of parameters to calculate the rolling code. This procedure is a vital step in ensuring security because the default parameters are the same for every transmitter. You need to personalise the parameters to prevent another transmitter that has the same identity from possibly operating your receiver. If randomisation is not done there is the risk that someone else’s transmitter that also has not been randomised will operate your receiver. To randomise a transmitter, simply connect the jumper shunt into the LK1 position. The transmit LED will flash at a 4 per second rate for the duration. Wait for a short period (say several seconds to a few minutes) then remove the jumper. To prevent losing the jumper, it can be stored in the “keeper” position when finished. Parameters are altered every 40s and that is 25,000 times per second, so they will end up being different for each transmitter. The randomisation relies on the fact that it would be impossible to randomise two transmitters over exactly the same period by plugging and unplugging the jumper plug to within 40s of the same period. Add this to the fact that we do not specify a particular period to run the randomisation (as we leave this up to each individual person); a unique set of rolling code parameters is ensured. Registering After randomisation, the transmitter needs to be registered with the receiver in order to work. Both transmitter and receiver must be readied for this. Place the transmitter September 2009  83 EXTERNAL SWITCH CONNECTION OPTION (JAYCAR SP-0702 OR EQUIVALENT, MOUNTED ON LID) Fig.7: wiring the controller to external devices. CON3 (door strike) output is effectively in parallel with RELAY1 COM/NO contacts so it would not be normal to have both wired. But you can do so if your application calls for it. CABLE TO ELECTRIC DOOR STRIKE CABLE GLAND TP 12V V 0 WS V 2 1 0V P-TYPE NYLON CABLE CLAMPS 3 2 RELAY3 F0 1 V 5 PT D N G SK NIL 1S D N G PT S1 TPS1 1P T GND DNG RELAY2 1 2P T S3 S2 4 56  BC DE 4 C 1 A 2 C 8 23 OUT RELAY1 TPS2 78 9 2-CORE SHEATHED 7.5A MAINS FLEX CABLES 3P T TPS3 CON2 CON3 +12V CON4 M4 x 10mm SCREWS WITH M4 WASHERS & NUTS UHF ROLLING CODE RECEIVER 15008092 CON1 CABLE GLANDS G NI H CTI WS CAV 0 3 2 jumper in the LK2 position and at the receiver, place the LK1 jumper in the ‘in’ position. Now press and hold S3 on the receiver and then momentarily press S3 on the transmitter (with the transmitter about 1m away from the receiver). The acknowledge LED on the transmitter will flash twice and the receiver’s acknowledge LED should then flash on and off at a 1-second rate until S3 on the receiver is released. This 1-second flashing is an indication that the registration process has been successful. If the LED does not flash, then registration was unsuccessful so try again. Release S3 on the transmitter and receiver, then press and hold S3 on the receiver again and momentarily press S3 on the transmitter. If the registration process still fails, try re-randomising the parameters and then register again. The randomisation and registering procedure must be done for each new transmitter. Note that registering a transmitter will prevent the use of a previously registered transmitter if it has the same identity. For this reason transmitters need to have their own identity. A different identity transmitter can be registered with the receiver without affecting the registration of the other transmitter. Testing transmission If registration was successful, the LK2 jumper can be 84  Silicon Chip removed from the transmitter and placed in the keeper position. Switch S3 on the receiver should by now be released. The receiver is now ready to respond to the transmitter on the second press of one of the transmitter switch buttons. Pressing a switch on the transmitter for the second time should activate the corresponding relay on the receiver. It should activate the relay on each successive press of a switch thereafter. Lockout Any transmitter that has been synchronised can be later locked out from operating the receiver. To do this, insert LK1 on the receiver in its ‘in’ position. Then set BCD1 to the identity number of the transmitter you wish to lockout. Note again that the A, B, C, D, E and F positions on BCD1 are the 10, 11, 12, 13, 14 and 15 identities. Press S1 and the acknowledge LED will light once for 1 second. Then it will flash briefly for about 0.25s a number of flashes equal to the identity number. For identity 0, only the 1-second flash will not occur because the identity is zero and so does not briefly flash. Put another way for identity 0, the LED does flash but for zero times. After flashing the identity number, the LED will remain off for 3 seconds. If S1 is held pressed the cycle of displaying a 1-second flash and then the identity number siliconchip.com.au Use this photo in conjunction with the diagram at left to ensure that your project looks the same when completed. Note that the nuts for the three P-type cable clamps (right side) are all soldered to the underside of the PC board to make final assembly much easier. will occur again. This cycle will occur only for three times, as S1 is kept held pressed. After this if S1 is still held pressed the LED will then stay lit. This ‘stay lit’ indication means that now all identities are locked out. When all identities are locked out, re-registration will be necessary for each transmitter that is in use. To open the case remove the self-tapping screw and take off the battery cover compartment by prising at the holes where the keyring attaches. The lower half of the case is removed by squeezing the sides of the top half of the case to release the catches from the base. Transmitter case Using Fig.6 as a guide, mark out and drill the holes in the side of the box for the four cable glands and the power lead connector. At this stage you can also drill the holes for the four cable glands but don’t put any wire in yet. The PC board is secured in the box using the integral corner pillars. These accept M3 x 10mm screws. While the three on-board switches will generally not be needed once setup is finished, some constructors may wish to fit external switches so the relays can be activated without the keyfob transmitter (ie, a “local” mode). In fact, external switches can completely replace the on-board switches. In this case momentary push to close switches can be installed onto the lid or side of the case and wired as shown in Fig.7 to TPS1, TPS2, TPS3 and GND PC stakes. A suitable switch is the Jaycar SP-0702. If you decide not to install S1, S2 and S3 on the PC board because you are placing switches on the lid, note that the ground track on the PC board is connected via the lower two Switch caps supplied with the keyfob case are designed to fit over the switch actuators of S1-S3. You may find that when the lid of the keyfob case is in place, the switches are already pressed. Note also that IC1 must be pressed fully into its socket so that S1 can be operated. The top of each switch actuator may need to be shortened by a very small amount so the switch is not depressed when the lid is in place. Take care with filing the actuator so not too much is removed. If you do remove too much, the switch will not work, as the switch cap will touch the switch body before the actuator is pressed. To solve this the bottom of the switch cap can be filed to prevent it touching the switch body. A translucent light pipe diffuser is supplied with the case and is inserted into the hole in the top of the lid. The rounded triangular wire for a keyring attachment is placed in the case lid at the battery end of the case. A self-tapping screw holds the lid secure at the battery end of the case. siliconchip.com.au Receiver in its box September 2009  85 Table 2: Momentary period settings Momentary period settings for VR1, VR2 and VR3 with Voltages as measured at TP1, TP2 and TP3 respectively. Timeout periods are adjustable in 0.26s increments to 2s, then in 1s increments from 5 to 10s. Adjustments in 5s increments are made above 10s. Not all available timeout periods are shown in the table. You would need to interpolate the values for other timeouts. For example, to set for 2.5 minutes adjust the trimpot to between 2.79V (2 minutes) and 4V (3 minutes). A 3.4V setting should be close enough for 2.5 minutes timeout. TESTPOINT TIMEOUT VOLTAGE (V) 0 to 0.18........... 0.26s 0.26............... 0.52s 0.34............... 0.78s 0.41............... 1.04s 0.49................ 1.3s 0.57............... 1.56s 0.65............... 1.82s 0.73................ 2.0s 0.81..................3s 0.88..................4s 0.97..................5s 1.36.................10s 1.44.................15s 1.68.................30s 1.92.................45s 2.15.................60s 2.47.................90s 2.79............2 minutes 4..............3 minutes 5............ 4.4 minutes bridging terminals of switch S1. Removing S1 will mean you need to place a horizontal wire link between the lower two horizontal holes left after removing the switch. S2 and S3 positions do not require any links. A note to this effect concerning S1 is located on the underside of the PC board. Wiring into equipment For an electric door strike, which is usually rated at less than 1A, you can use CON4 to directly drive the strike with 12V. The wires pass through a cable gland in the side of the box. The relays are provided for switching 230VAC mains to power lights, door motors, etc. The relays do not supply any power – they can simply be regarded as a switch. If controlling a light, for example, the pair of wires from each relay (common and NO) are simply wired across the light switch. For two-way light switching, the common, NO and NC contacts would need to be used. These three contacts are available for outputs from Relays 1 and 2. If you want to control a garage door, you would wire across the push button switch “local” door control switch Fig.8 shows how this is done. The push-button switch almost invariably controls a low-voltage circuit (hence they can use bell-push switches) so this can be run using light-duty figure-8 cable. If using this mode, make sure the system is set for momentary operation – garage door controller local switches are almost invariably wired as push to open, push again to close. And some controllers might not like a long-term short across their local switch! Switching mains For switching 230V mains, the wire must be sheathed 2 or 3-core mains flex (depending on what you are switching), rated at 7.5A 230VAC. Use 10A wire if switching more than 7.5A. In Australia, a licensed electrician must wire anything connected permanently into the 230V supply. The wire is passed through a cable gland in the box end 86  Silicon Chip 3.3k A LED3 1 EXISTING GARAGE DOOR CONTROLLER “LOCAL” PUSH BUTTON RELAY3 K  D3 K A B C Q3 BD681 2 3 COM NO CON2 TO GARAGE DOOR CONTROLLER ADD GREEN WIRING E Fig.8: connecting to an existing garage door controller is really simple (and safe!) if your system has a “local” pushbutton switch to open and close the door. This section of the circuit shows relay 3 but any of the three relays could be used – wire in the COM and NO terminals. Note that this would require the Rolling Code Remote Control to be used in “momentary” mode. and secured using a P-clamp that is attached to the PC board with an M4 x 10mm screw washer and nut. We soldered the M4 nuts to the underside of the PC board. This allows securing the P-clamps in position without accessing the underside of the PC board. If the 2-core wire is not held tightly enough in the P-clamp, enlarge the diameter of the wire by placing a short length of heat shrink tubing over the wire. Use a second layer of heatshrink tubing, if one layer is insufficient. The cable gland also helps secure the wire when tightened. Note that these glands are easily undone from the outside of the box and so do not meet Australian standards for mains wiring where wiring is required to be securely held in place; hence the need for the P-clamps as well. After wiring, replace the plastic cover over the CON1/ CON2 terminal strip. It snaps into place when the PC board is mounted in the case (otherwise it slides in from the side). Disable existing controllers? While this controller should operate quite happily in conjunction (parallel) with an existing wireless garage door controller, it could become confusing to the operators. Because you can add up to 16 transmitter remotes, you’re not likely to need the old unit anyway. We suggest disabling the existing wireless receiver. The best way to do this would be to disconnect power to the receiver without disconnecting power to the controller itself. However, in many commercial garage door openers, the receiver and door control circuitry are combined so this might prove difficult. Because of the variety of commercial garage door controllers, we cannot offer any real advice in this area – except to say that it might be as simple as removing the external (wire) antenna which most have fitted. This should make the existing receiver “deaf” enough so that nothing happens if an old transmitter button is pressed! Errata from Part 1 of this project (August 2009) On page 77, discussing the BCD switch, should read: Position 15 (or F) sets all switch outputs at 0V. Also on page 77, on the circuit diagram, the terminal second from bottom on CON2 is of course the common terminal for relay 3. On page 81, where it says we need a seven-way barrier terminal, we actually need an eight-way, as described and shown in the photographs. siliconchip.com.au Frequently Asked Questions Q: What happens if the transmitter is out of range and one of the transmit switches is pressed? Will the receiver still work when the transmitter is later brought within range and the button pressed again? These questions are asked because the receiver was expecting a code that has already been sent and the transmitter has rolled over to a new code. So how does the system get around this problem? A. The answer to this is that if the signal format is correct but the code is incorrect, the receiver then calculates the next code that it would expect and checks this against the received code. If the code is now correct the receiver will operate. If the code is still incorrect, the receiver calculates the next expected code and will do this up to 100 times. If none of these are correct, the receiver keeps its original code and it will not trigger. So the transmitter buttons can be pressed up to 100 times while out of the receiver’s range without problems. transmitter and receiver will use these numbers to perform the calculation. The values quoted for the multiplier and increment value are not as simple as 100 and 7 but are 24 bits and eight bits respectively in length. Without knowing both the multiplier and the increment value, it would be very difficult to predict the next code. This is particularly true because of the very large numbers involved. The code length is 48 bits with as many as 2.8 x 1014 combinations. This reduces by a factor of 100 because of the lookahead feature to a 1 in 2.8 x 1012 chance of striking the correct code – still impossibly long odds. Code scrambling A further complication with the transmitted code is that the code is not necessarily sent in sequence. There are also 32 possible scrambling variations that are applied to the code and the scramble changes each time that code is transmitted. Q. How do you restore the transmitter operation? A. The only way to trigger the receiver after this is to reregister the receiver with the transmitter. A different registered transmitter will still operate the receiver. That’s because this transmitter has a different identity and a different code to the other transmitter. Automatic Re-registration Some rolling code transmitters systems offer automatic registration if the transmitter and receiver lose synchronisation. In these systems, the receiver includes a code “lookahead” feature as described above but the number of look-ahead codes is usually limited to fewer than 100. What happens is that if the code is not recognised after all the look-ahead calculations have been made, the receiver changes its synchronisation method. Basically, the receiver requires two separate transmission codes before restoring correct operation. On the first transmission, it calculates the next code it should receive using this received code as the basis for calculation. If the second code sent by the transmitter is the same as the code that was calculated, the receiver operates. The drawback of this latter scheme is somewhat less security since, in theory, two successive transmission codes could be intercepted and recorded. These codes could then be re-transmitted in sequence to re-register and thus trigger the receiver. Q. What if the rolling code calculation results in two consecutive codes that are the same and the code is intercepted and re-transmitted to open the lock? A. This is highly improbable and our rolling code transmitter has safeguards preventing the same code appearing twice in succession. For each code calculation, a comparison is made between the current and last code. If the code is the same, the code is recalculated after an increment of the code value to ensure successive code calculations diverge. It is this new code that is transmitted. The receiver performs the same re-calculation so that the new code will be accepted. A warning, though, is that, as with any encoded UHF encoded transmission, the signal can be intercepted and recorded. When played back it can be used to unlock a receiver. This is particularly true of fixed code systems where the same code is always used. For rolling code systems, a capture of the transmitted code can be used to unlock the system if the code is captured when the transmitter is used out of range from the receiver. The captured code could then be used to unlock the receiver if it is transmitted before the genuine transmitter is used to unlock the receiver. The captured code will only work once because the receiver will change to its new code upon reception of the signal. The captured signal will also be nullified if the genuine transmitter is used to unlock the receiver. Q. How does the receiver know which code to expect from the transmitter, since this changes each time? A. The answer to this is that the transmitter and the receiver both use the same calculation to determine the next code. They also both use the same variables in the calculation and these variables tend to be unique values that no other transmitter uses. For example, if the calculation for consecutive codes requires the original calculated code to be multiplied by 100 and the number 7 added to it, then both the Q. Does each transmitter use the same rolling code calculation and if so, wouldn’t the receiver lose its synchronisation if several transmitters were used? A. Each transmitter is treated independently to another and uses different rolling code and calculation parameters. So a receiver will not lose synchronisation with a particular transmitter, even if it is not generally used. Imbedded in the rolling code is the transmitter identity value from 0-15 and so the receiver knows which transmitter is sending the signal. SC siliconchip.com.au September 2009  87 Vintage Radio By RODNEY CHAMPNESS, VK3UG Kellogg TRF receiver: home made or manufactured? ally impossible to distinguish between home-made and commercial receivers on the basis of their construction. Certainly, in those early days, there was no need to tip a chassis upside down to access components. In fact, there was no chassis – that innovation came towards the end of the 1920s. The Kellogg company This simple little receiver is an excellent example of a 3-valve TRF set from the mid-1920s and has quite reasonable performance. Its exact origin is somewhat obscure, however. I N THE EARLY DAYS of radio/ wireless, many listeners used homemade receivers to pick up the broadcasts. Some early experimenters even made some of the components and only bought those parts they couldn’t make themselves, such as valves. Of course, this strictly wasn’t necessary as many companies supplied a variety of parts for radio constructors as well as making their own radios. The set described here is owned by Mark and was restored by Marcus, 88  Silicon Chip both fellow club members. All of us are unsure as to whether it is a Kellogg receiver made by the Kellogg company, a home-made receiver made using Kellogg parts or a receiver built from a kit supplied by Kellogg. In fact, it’s often not easy to be 100% sure as to whether receivers from the 1920s were home-made or built by a manufacturer. All used the ubiquitous breadboard construction style of the era, with the parts mounted on the top of the breadboard. As a result, it’s usu- In Australia, the name “Kellogg” is synonymous with cornflakes. However, the company we’re talking about here was started by Milo Kellogg of Chicago, who established the Kellogg Switchboard and Supply Company in 1897. His factory concentrated mostly on telephones and telephone equipment and was quite a large concern. Milo Kellogg was a prolific inventor and on one day in 1899 he was granted 125 patents for telephone-related equipment. Subsequently, when radio became the next technological advance, Kellogg began making components for receivers and other equipment. I am unsure as to whether they manufactured complete radios or not but they certainly made some high-quality components, as is evident from their 1923 catalog. Kellogg remained an independent company until 1951 when ITT bought a controlling interest. The Kellogg name subsequently remained until 1962 when it became ITT Kellogg and then in 1965 it changed again to ITT Telecommunications. There were several other amalgamations into the 1980s and it is now a part of Cortelco. The circuit The Kellogg, for want of a name, is a conventional 3-valve TRF receiver from the mid 1920s. The antenna tuned circuit consists of a single winding that is tapped for different-size siliconchip.com.au Fig.1: the circuit is a simple TRF receiver based on three UX201A triode valves. V1 is the detector while V2 & V3 are audio amplifier stages. antennas. It also has a tapped feedback winding for regeneration (or reaction). The top of the tuned section feeds a parallel 150pF mica capacitor and 5MΩ resistor. This combination forms a “grid leak” and is connected to the grid of V1, a UX201A valve used as a regenerative detector. Regeneration is controlled by the variable capacitor connected between its plate and the tuned circuit. Some readers will not be familiar with the terms “regeneration” and “reaction”, both of which are generally used to mean the same thing. To explain, early radio valves had quite low gain and were expensive, so every endeavour was made to get the most out of each valve. And that’s where regeneration came in. Regeneration is a technique whereby the incoming radio signal is amplified and then a portion of this amplified signal is fed back to the input again and re-amplified. As a result, the overall gain of the stage is multiplied many times. This means that the stage may have as much gain as a more complicated (but non-regenerative) circuit using one or two additional valves. Each technique has its advantages and its disadvantages. A regenerative detector is simple, cheap to make, sensitive and reasonably selective. However, it can be difficult to adjust for optimum performance, which makes it unsuitable for non-technical users. In addition, the audio output has higher distortion levels than that from most superhet receivers. In the 1920s, however, before susiliconchip.com.au This is the view inside the set with the top cover removed. Note the breadboard style of construction, with all parts readily accessible from the top. perhets became available, enthusiasts had little option but to accept sets with regenerative detectors if they really wanted to listen to radio. Following detection in V1 the audio component of the signal appears at the plate of the valve and is fed though a radio frequency choke (RFC) to the primary of T1, an iron-cored 1:3 step-up transformer. A 201 valve has a nominal gain of around eight and by feeding its output to this transformer, the overall theoretical gain becomes 8 x 3 = 24. From there, the signal is applied to V2 where it is amplified and applied via another audio iron-cored 1:3 step up transformer (T2) to a third UX201A valve (V3). The amplified audio signal is then fed to a high-impedance horn speaker. Step-up transformers Step-up transformers were necessary in the 1920s because the valves September 2009  89 the frequency response was limited to around 300Hz-3kHz but even that would have had 10dB peaks and troughs over its range. It may have sounded terrible but that’s all that was available in the 1920s. Finally, the filament rheostat and the regeneration control set the volume of the receiver. The filament rheostat also acts as the on-off control. This works by having the wiper break contact with the wire resistance element at one end of the control’s rotation. Restoration These two photos show the tuning knob before (top) and after repair (bottom). The small central knob is the vernier fine-tuning control. of that era had such low gain. Their main disadvantage was that the audio quality was increasingly degraded as the step-up ratio increased. However, that didn’t matter all that much as the detector itself had considerable distortion, as did the horn speakers that were used. In fact, it’s probable that none of the early sets had distortion figures below about 20% or more. In addition, Like almost all “ancient” radios, the Kellogg TRF receiver wasn’t exactly in pristine condition when Mark obtained it some time ago. The cabinet, however, was still in remarkably good condition. It was dusted out with a brush and a vacuum cleaner and then rubbed down with linseed oil to make it look almost new again. The dial had a section that had broken away but fortunately, the broken piece was supplied with the set. The dial, the dial shafts and the tuning capacitors are rather unique. As usual, a large knob turns the main part of the tuning capacitor but now we come to the unusual part of this tuning gang – a separate shaft inside the main tuning shaft controls a vernier plate at the back. The tuning knob for the vernier is the small knob in the centre of the main dial. It’s a very clever way of doing the job but it would have required more precision during manufacture than a more conventional tuning gang and so would have been more expensive. Of course, the added complexity also makes it difficult to repair any damage if the set is mishandled. And that is exactly what had happened in this case – the set had been dropped at some stage and had landed on its tuning knob. As a result, a section had broken out of the knob and although this was easy enough to repair, considerable damage had also been done to the tuning capacitor shafts. Suffice to say that the repairs to the dial mechanism were not done in five minutes. On the contrary – professional machine-shop equipment was needed to drill and realign the mechanism. The earthing braid that was on the centre shaft had fatigued and broken off too. It was replaced but it appears as though it will be a continuing problem that requires routine repair. Just why such a complex and costly mechanism was produced for sets like this is anyone’s guess. Missing valves The set was obtained with just one valve in place and this proved to be a Philips A415. However, although a variety of valves could be fitted to the set (the valve base arrangements at that time were reasonably standardised), it was decided to fit UX201As to the receiver. They weren’t cheap but are more applicable to this American-style set than Philips valves. Once the valves had been obtained, it was discovered that the filament polarity had been reversed in the wiring. This was easily corrected. Further checking of the circuit revealed that there was a short to the 5MΩ grid leak resistor and that audio transformer T1 had an open-circuit winding. The short to the resistor was easily fixed but then it was discovered that the resistor had gone high in value, to 14MΩ. This resistor is a into VIDEO/TV/RF? Television & Video Technology – by KF Ibrahim New edition has a full and compre-hensive guide to NEW LOW PRICE! video and TV tech-nology including HDTV and DVD, $ 58 starting with fundamentals. $ 70 DVD Players and Drives $ 95 NEW LOW PRICE! 85 $ – by KF Ibrahim DVD technology and applications - ideal for engineers, technicians, students, installation and sales staff. Practical Guide To Satellite TV – by Garry Cratt The book written by an Aussie for Aussie conditions. Everything you need to know – including what you cannot do! 7th ed. $ 49 Hands-On Zigbee – by Fred Eady $ 96 50 NEW LOW PRICE! $ 75 An in-depth look at the clever little 2.4GHz wireless chip that’s starting to be found in a wide range of equipment from consumer to industrial. There’s something to suit every RF fan in the SILICON CHIP reference bookshop: see the bookshop pages in this issue $ 75 RF Circuit Design – by Chris Bowick A new edition of this classic RF text - tells how to design and integrate RF components into virtually any circuitry. NEW LOW PRICE!design 74 $ Practical RF H’book – by Ian Hickman A reference work for technic90 ians, engineers, students and NEW LOW PRICE! the more specialised enthusiast. Covers all the key topics in $ 73 RF that you need to understand. $ ! Audio ! RF ! Digital ! Analog ! TV ! Video ! Power Control ! Motors ! Robots ! Drives ! Op Amps ! Satellite 90  Silicon Chip siliconchip.com.au The tuning gang is unusual in that it features an additional single moveable plate at the back which is controlled by a separate shaft inside the main tuning shaft. This allows the station frequency to be precisely adjusted when tuning. glass-mounted type and could not be dismantled without risk of damage, so an 8.2MΩ resistor was wired across it. This brought the total resistance down to the required 5MΩ. The audio transformer problem was fixed by replacing it with a new one. This, along with the valves, was obtained from overseas, as they are difficult to find in Australia. With the faulty parts replaced, it was time to test various sections of the set. To do this, an antenna, earth, horn speaker and external power supply were connected to the set and the supply’s DC outputs adjusted to the levels suggested in the valve data sheets. This ultimately consisted of 5V for the three filaments, -4.5V to bias the two audio stages, +100V to the plate circuits of the audio stages and 45V to the detector. The 45V HT for the detector was derived from a variable power supply. At just 17V HT, the detector was going into oscillation so it was in good order and some stations could be heard behind the whistling. However, an HT of 45V appears to be about optimum for this stage. Certainly, regenerative detectors used voltages ranging from 22.5-45V for valves such as the 201A during that era. At full volume (ie, minimum resistance setting of the filament rheostat), the set had a tendency to go into supersonic oscillation. As a result, a 500pF capacitor was wired from C- to A+ and this fixed the problem. Sets of this era had little if any decoupling, instead relying on the batteries to act as siliconchip.com.au The regeneration (or reaction) control resembles a mica padder capacitor. Rotating the control knob varies the distance between the plates and thus the capacitance and the amount of regeneration. filters and de-couplers between stages. In addition, the sets had relatively little gain so extensive decoupling was unnecessary. One problem with this type of circuit is that the audio transformers sometimes had to have their primary or secondary leads transposed to prevent feedback. In other words, the terminal marked “grid” has to be connected to the bias line while the “bias” terminal has to go to the grid, for stability to be achieved. The power leads from the set are connected via an octal plug into a purpose made AC power supply. This eliminates the possibility of errors being made when connecting the set to power. Alignment & performance There are virtually no alignment adjustments to be made in this type of set. The tuned winding has no alternate taps to alter the tuning range and must be accepted as it is. However, the antenna can be tapped at two points and a simple switch selects between them. The tapping nearer to the earth end of the tuned section is intended for long antennas, while the higher tap results in greater gain from the set to compensate for short antennas. The regeneration winding has one tap so that either it or the end of the winding can be selected to ensure regeneration with either a 22.5V or 45V supply. The regeneration control is rather unusual and is constructed somewhat like a mica padder capacitor. When the plates are brought closer Three UX201A triode valves are used in the old Kellogg TRF receiver. together by rotating the control, the amount of capacitance increases and the regeneration increases. Not surprisingly, the set is not parSeptember 2009  91 A close-up view of the “Little Spitfire” decal that’s attached to the horn-load­ ed loudspeaker that’s now used with the Kellogg receiver. with a 50mm speaker mounted above it. As a result, it still looks original and its performance is pretty much as expected of a horn speaker, as it still has the original horn baffle. Summary The old Kellogg 3-valve receiver was built into a wooden cabinet which is still in good order. The on/off volume control is at bottom left, while the reaction control is at bottom right. ticularly sensitive but was probably average for its time. However, it has good selectivity and is able to discriminate between adjacent stations quite well. The loudspeaker The “Little Spitfire” horn speaker shown in the photos didn’t come with the set but is the type of speaker that would have been used with it. This item was obtained separately but unfortunately its high-impedance winding was open circuit. Rewinding the coil to get the speaker going again wasn’t worth the effort. Instead, its internals were removed from the base and its mounting points modified so that a small line-to-voicecoil transformer could be fitted, along As with many very old receivers, this unit required a lot of work to restore it to working order. However, it’s now a good-looking set and is an excellent example of a mid-1920s TRF receiver. Its performance is fair and its ability to discriminate between stations is good. A 10kW broadcast transmitter is located just 8km away from my location, while a second 5kW station is also located at a similar distance. Together, these two station provide a good test of a set’s selectivity. Finally, I’d like to thank Marcus who supplied me with the photos and SC information for this article. Looking for real performance? • Learn how engine management systems work • Build projects to control nitrous, fuel injection and turbo boost systems 160 PAGES 23 CHAPTE RS Fro m the pub lish ers of • Switch devices on and off on the basis of signal frequency, temperature and voltage • Build test instruments to check fuel injector duty cycle, fuel mixture and brake and coolant temperatures • Speedo Corrector, Turbo Timer & Digital Thermometer Projects Price: Aust. $A19.80 plus $A10 P&P ($A12 P&P NZ; $A18 P&P elsewhere). See the order form in this issue. Intelligen t turbo timer I SBN 095 852 9 7809 5 294 - 4 8 5229 4 $19.80 (inc GST) TURBO B OOST & nit rous fuel co ntrollers 6 NZ $22.00 (inc GST) How eng in manageme e nt works Order by phoning (02) 9939 3295 & quoting your credit card number; or fax the details to (02) 9939 2648; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. 92  Silicon Chip siliconchip.com.au 1 2 3 4 5 6... NOW AVAILABLE: SIX MONTH SUBSCRIPTIONS & AUTO RENEWALS In these tough economic times, we understand that taking out a one or two-year subscription may be difficult. Or perhaps you’d like a trial before committing yourself to a full sub. Either way, we’ve made it easy with our new six-month subscriptions. It’s the easy way to make sure you don’t miss an issue . . . and a six month subscription is STILL CHEAPER than the over-the-counter price AND we pick up the postage tab. 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Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097 or send an email to silicon<at>siliconchip.com.au Audio filter capacitors Regarding capacitor selection for an audio filter, I discussed polyester capacitors with a friend and she showed me a book on the subject. It points out that a problem with polyester capacitors is their poor temperature stability. In a filter, to some extent, you don’t want the frequency shifting with temperature changes. According to that book, polypropylene capacitors are about as good as polystyrene and they reckon they’re better in all three categories than polyester (accuracy, temperature stability and leakage). Any comments on this? I would like to know whether there’s any reason to pay the extra that polypropylene costs or should I stick with polyester in most applications? (N. V., via email). • We don’t think temperature stability is particularly important for audio circuits, with the possible exception of notch filters. To get an idea of the significance of temperature stability, have a look at the likely capacitance variation. Polyester has the highest temperature coefficient for a plastic dielectric capacitor but if you look at the variation from 0°C to 70°C, it is likely to be less than 1.5%, ie, not worth worrying about for the vast majority of circuits. Yes, such a variation will shift the corner frequency of a filter but not by much. On the other hand, we would avoid using any type of ceramic capacitor (disc, tubular, monolithic etc) for filter circuits as they are definitely inferior to plastic dielectric capacitors. USB charger for motorbike I need to charge a GPS device from my motorbike via a Mini-B USB plug. I was thinking I would get a normal cigarette lighter charger with the cigarette plug on one end (with a built-in 12V-to-5V converter) and USB on the other end. I would then cut off the USB end and solder on a waterproof female USB A plug, which comes with a cap for keeping it waterproof when not in use. At the other end, I was thinking about taking the cigarette lighter part apart, waterproofing the lot within some resin and adding a small fuse before it and connecting it directly to the battery. This avoids any cutting of wires (voiding the bike warranty) and makes the whole thing easy to remove later. My question is, will connecting one of these 12V-to-5V converters directly to the battery always drain a small amount of power, even when there is Multiple Laptops Cause Power Overload My school has a laptop trolley with 16 Apple Macs on it. All have chargers rated at 1.5A maximum so why does the power point they are plugged into trip out circuits and spark at the switch? I have tested the current with a clamp meter to be around 2.5A continuous. Is it because of a splitsecond load draw or back-EMF or something technical like that? Please help – this is a major problem. (W. S., Rockingham, WA). 94  Silicon Chip • Your laptops are tripping out your power circuit because they have switchmode power supplies and these have high inrush currents at the instant power is applied (ie, for the first cycle or so). Try powering your laptops up in groups of four (eg, by connecting them to four separate switched power boards). That way, the current drawn by each group of four will have time to stabilise before power is applied to the next group. nothing plugged into the USB cable? If it will, what is the likely current drain when not in use? I do not want this thing to drain the battery when the bike is left in the shed for two or three weeks. The only other option is to put a switch inline before the 12V-to-5V converter or cut into the power cables after the ignition switch (cannot do due to voiding warranty). (D. E., Ainslie, ACT). • You would need to measure the standby current drawn from the 5V charger as it would depend on the internal circuitry. Some would have a linear 5V regulator that would draw 10-20mA standby while others would use a switchmode supply that may have a much lower standby current For a bike battery, you would need to have a low standby current of preferably below 1mA to prevent it discharging after two or three weeks. Speed controller for bench grinder Over the years you have published several circuits for motor speed controllers. I’d like to control the speed of a typical 150mm, 150W bench grinder with a wheel at each side. When sharpening tools this type of grinder runs too fast and overheats the tool. Ideally, it would be great to have a set-up so that, when sharpening tools on the very fine wheel, I could flick a switch to drop the speed to half. A drop in power isn’t an issue as when sharpening plane blades etc, little power is required. Then for serious grinding fabrication etc, I could just flick the switch for full power and use the coarse wheel. Would any of your circuits be suitable? I would construct it to just have a fixed speed. (K. W., Newport, Vic). • As far as we know, all bench grinders are based on induction motors which run at a fixed speed (usually 1440RPM) which is shown on the nameplate. The only way their speed siliconchip.com.au Multiple CFLs Can Cause Switch-On Problems I have been enjoying your articles on CFLs (compact fluorescent lamps). I have been experimenting with different types at home over the years, with various colours, styles and wattages. Recently, I needed to change one bulb on a light fitting that has 10 light bulbs. Since the light fitting hangs from the second storey ceiling over the stairwell, I thought I’d do the job once and change all 10 incandescent bulbs over to CFLs. There were 10 25W incandescent bulbs, so I bought 10 8W B22 Philips Tornado CFLs in warm white. I chose these because of their small size and weight. I also find that the Tornado type warm up a lot quicker than other types. 8W is equivalent to 40W incandescent (I have found this to be a little over-rated). After installing the 10 CFLs I switched the lights on to test them before I put back the light covers. (Actually, I got my wife to flick the switch as I hung from the plank of wood suspended across the hand rails). Click . . . no lights – the circuit breaker had tripped. can be varied is if they are driven with a speed controller which varies the output frequency and voltage. We have not described such a controller. Question on battery capacity I have acquired a battery and would be interested to know its amp-hour capacity as it is not stated on the battery label. I believe it is an AGM battery from a large UPS. The label shows it to be a SPRINTER S12V300F 12V 300W/cell. As it is a sealed battery I cannot tell how many cells are in it. It must have a fairly large capacity as I am using it for camping and it ran my Waeco fridge in the back of the ute for four days in 30°C+ heat. It would be very much appreciated if you could explain how to convert from watts/cell to amp-hours. (D. J., Hallett Cove, SA). • The 300W/cell rating does not provide the battery capacity but just the power it can deliver. Capacity is the siliconchip.com.au I tested all the CFLs one at a time and all tested OK. I then installed one CFL at a time and asked my wife to flick the switch after each one. All was going well until the eighth one was installed, whereupon the circuit breaker tripped. Now I know that CFLs draw more current at switch-on but I would not have thought to the point of tripping my 10A circuit breaker. I eventually installed seven CFLs and three incandescents in the light fitting. I then turned on all the lights on this circuit and then turned on the 10-way fitting last. That worked. So what is causing the circuit breaker to trip? Would it be leakage to ground in the light fitting because there is too much current draw at turn on? Is there a formula to work out the current drawn from a CFL at turn on? (Z. J, Cordeaux Heights, NSW). • This is yet another drawback of CFLs although it normally does not arise because few light fittings require so many lamps. If you refer back to the April 2007 issue, on page 15, you will see a amount of energy it can deliver over time. The watt-hour rating for the battery depends on the discharge current and is higher for lower currents. A 12V lead-acid battery has six cells. Because the cells are in series and each cell is around 2V, the current through each cell at 300W is about 150A. For 12V with six cells in series, the power is 1800W so it can provide 150A at 12V. If you do an internet search for your battery you will be able to find its data sheet which shows the capacity information. Huge 400Hz inverter wanted Have you ever described a 12V or 28V 400Hz inverter, at around 200kVA at 115V or 250VAC? Restorers/users of some military/avionic equipment would welcome suggestions as to how best attain this. Is it feasible to modify an existing 240V 50Hz inverter to do the same job? Sinewave output is pref- typical circuit for a CFL. Its input circuit is effectively a bridge rectifier and 4.7µF capacitor, with inrush currents limited by a 47Ω resistor. Neglecting the impedance of the capacitor, the initial surge current, if switch-on occurs at the peak of the 50Hz 230VAC waveform, could be in excess of 6A. When you put 10 CFLs in parallel, you have 10 times the initial surge current and that could be up around 60A. This is far more than the initial surge current of the equivalent 250W incandescent lamp load which would typically be around 10-15A for less than one cycle of the 50Hz mains supply. In fact, we are only guessing what the true surge current is but you can understand the mechanism behind it and grasp that it could easily trip your 10A circuit breaker. You may be able to solve the problem by increasing the circuit breaker rating to 15A or you may need to connect this particular light fitting to one of your 15A power circuits. You will need to consult a licensed electrician to have this done. erable and it has been suggested that a 400Hz oscillator feeding an audio amplifier might be acceptable. Your suggestions would be appreciated. (P. W., Metung. Vic). • A 200kVA inverter is a massive unit and it would not be feasible to power one from a 12V or 28V source as the currents would be excessive. And using an oscillator and amplifier to deliver 200kVA at 400Hz and with Ozitronics Tel:(03) 8813 2110 Fax:(03) 9011 6220 Email: sales2009<at>ozitronics.com 4-Channel Temperature Monitor and Controller Features 4 temperature inputs (DS1820) and 4 relays for output control. Simple text commands via RS232 to read temperature and control relays. Can be controlled by terminal program or via free Windows application. Pluggable screw terminals for sensors and relay outputs. K190 $104.50 More kits and all documentation available on website: www.ozitronics.com September 2009  95 Using An Audio Amplifier For The LF Amateur Band As you may be aware, Australian amateurs were recently given an allocation in the LF region from 135.7137.8kHz. The power limit is 1W EIRP which, at first glance, seems very low. However, given that any practical antenna (within amateur means) only achieves tenths of a percent efficiency, power levels of the order of 500W are permissible. A signal in this band could be considered as a very high audio frequency and many overseas amateurs have had success using high-power audio amplifiers as linear amplifiers. Of course, a transformer is required to match the low-impedance output of the amplifier to the standard 50ohm antenna impedance. As a result, I am considering building the Studio 350 Amplifier (SILICON CHIP, January & February a 250VAC sinewave is just unrealistic. The amplifier would need to produce a 250VAC waveform at 800A and its efficiency would be very poor. The power supply for the amplifier would need to be more than ±350V DC. A switchmode unit would be the best design but even then it would be a very large unit. Observations & queries on 6-Digit GPS Clock I like your 6-Digit GPS Clock (SILICON CHIP, May 2009) and I am working on building two or probably three of them. However, I do not like the idea of showing all the components in the clear “plastic-lidded” box. It is purely a personal objection, quite subjective and comes from dealing with commercial equipment. As a result, I have located several boxes in the Jaycar catalog, similar to that used to house the GPS-based Frequency Reference described in March 2007. I also notice from the PC board artwork that pin 26 on the PIC16F877A is connected to pin 33, an unused output on the same chip. That is an output is connected to an input. In my experience, this does not always give the required results. Has it had any adverse effects on the operation of the clock? 96  Silicon Chip 2004) and trying it on this band. I note that, as standard (and at 1W), the frequency response begins to roll off at 60kHz and looks to be about -4dB down at 137kHz. How does the frequency response at full power differ from that at 1W? Is it possible to extend the upper frequency limit? What problems can you foresee in using this amplifier at 137kHz? (D. S., via email). • That is an interesting question. While the frequency response at 1W may be above 137kHz, the power response (ie, frequency response with respect to full power) is likely to be no more than say 30kHz or 40kHz at best. We certainly have not tried driving it to full power at supersonic frequencies; for a start, the output matching network (L1, etc) would burn out. I propose to add two additional switches to put earths on the bases of Q19 and Q20 in order to prevent continuous operation of the seconds displays. I find it very distracting with the bars moving so frequently. However, the seconds display is necessary when setting other clocks to the correct time. With regard to the Daylight Saving Setting (DLS), is it possible to advance the time by more than one hour? I am asking this because I have a daughter in France and a brother in Canada and if it is possible to alter the difference by more than an hour then I can set the local time to that of France ie, UTC plus one or two hours and then add nine or eight hours to the DLS setting to give our local time. In other words, the system becomes two time zones rather than just an additional local setting. It will involve resetting the times when they change to DLS at both ends but this should happen only twice a year. It would also be convenient when working between Perth and the eastern states, as there is a two-hour difference in time normally and three hours during DLS. On a lighter note, I observe in the inset “UTC Local STD Time Offset” on page 28 of the March 2009 issue that if Russia is correct reading west to east The driver and output transistors are the main limiting factor here. Obtaining or making a transformer rated at 350W and suitable for 137kHz would also be no simple matter. However, it might be worth trying the amplifier driving a 50-ohm load directly, ie, without a matching transformer and without the output network (which might need to be redesigned to match a 50-ohm load). Given that the Studio 350 Amplifier will deliver 240W music power into an 8-ohm load, it should deliver over 35W and it might comfortably do it at 137kHz. The other point that needs to be considered is the likely duty cycle of the signal. If it is low, the amplifier would have a much easier time and would not be so likely to overheat. +3 to +12, then the USA and Canada should read east to west -4 to -8 (not west to east as printed). The fact that the time is immediately reset to being exactly correct after a power failure is very handy as it saves a lot of adjusting as is required with mains-operated devices such as clock radios and microwave oven clocks. As there is still enough room left on the modified PC board, after the EM408 receiver module is added, to accommodate the PIC16F628A unit from the GPS-based Frequency Reference in March 2007, will the newer EM408 GPS module still drive it? I am thinking of just putting on the tracks so that in the future I or others can add the chips to an existing set-up without having to go to a lot of trouble. (K. S., via email). • The PC board track running through pin 33 of the PIC 16F877A in order to reach pin 26 does not cause any problems, because the PIC firmware programs pin 33 (RB0) as an input, even though it’s not being used. Hence there is no interaction or adverse effects. It would require a fairly extensive change to the firmware to allow the “Daylight Saving Local Time” setting to be used as another local time setting, with an offset of its own instead of a fixed one-hour delay from local standard time. Sorry! siliconchip.com.au Notes & Errata 10A/230V Motor Speed Controller, May 2009: due to a tendency to highfrequency oscillation in comparator IC1b at the moment of switch on for the IGBT (Q1), it is possible that Q1 will be damaged with some types of load. The typical damage to the IGBT is a short circuit between emitter and collector; the motor then runs at full speed. Usually no other components are damaged. The cure involves three small changes to the circuit: (1) Connect a 220pF 50V ceramic capacitor between pin 7 of IC2c and ground; (2) Connect the collector of transistor Q4 to the wiper of speed pot VR1, instead of to the output of the IC1b. This prevents high-frequency oscillation during over-current events and provides a softer restart after an overload; (3) Increase the 10kΩ resistor from Q4’s base to ground to 100kΩ; the over-current protection now starts at about 26A instead of 48A. The accompanying circuit and PC board overlay diagram show these changes: (1) the 220pF capacitor is installed underneath the PC board between pins 7 & 8 of IC2; (2) the track from the collector of Q4 to the 4.7kΩ resistor is cut and connected to the “+” side of the adjacent 10µF capacitor using a short length of tinned copper wire; (3) the 100kΩ resistor is just below IC4 and one end connects to IC4’s pin 7 (GND). 12V Charge Controller, April 2008: a 10µF 16V PC electrolytic capacitor is missing from the circuit diagram (Fig.5) and the parts list. This capacitor connects between the adjust terminal and ground of the LM317 regulator, REG1. The wiring diagram (Fig.6) is correct. Over-Voltage Protector, Circuit Notebook, May 2009: the 3.6MΩ resistor in Fig.2 should be 1.2MΩ. with reversed polarity on both the circuit diagram (Fig.1) and parts layout diagram (Fig.3). In addition, the 100µF capacitor in series with the 100Ω resistor at the output (pin 7) of IC4b is shown with reverse polarity on Fig.1 (but is correct on Fig.3). There is no problem in setting the local standard time offset to any value in the range 0-23.5 hours, of course (see May 2009 article). You are quite correct about the UTC offsets for the time zones across the USA and Canada being shown in reversed order in the table on page 28 of the May 2009 issue. Thanks for pointing this out. Finally, we are not sure why you would want to add the PIC16F628A siliconchip.com.au SD Card Music & Speech Recorder/ Player, August 2009: the two 10µF capacitors in series with the wipers of VR2a & VR2b (volume) are shown from the GPS-Based Frequency Reference to the 6-Digit Time Display but in any case the EM408 module is not suitable for use in the Frequency Reference because it does not provide a 1pps (one pulse per UTC second) output – only the NMEA data sentences. Charger for an electric scooter I have a small electric vehicle (looks like a Vespa but doesn’t sound like one) which was supplied with a cheap switchmode power supply battery charger. The battery charger is very unreliable and among other faults, has destroyed several controller ICs and I’m unable to diagnose why it is doing so. I would like to replace it with the Charge Controller described in the April 2008 issue. Could you please run a critical eye over the following September 2009  97 Increased Range For Battery Capacity Meter I have been reading your articles on the Smart Battery Capacity Meter with great interest. This project is very similar to a commercial product – the Xantrex Xlink 10 emeter. Is there a way to add a prescaler to handle larger voltage and current, as used in an EV, assuming that the software also has to be changed as well? (J. D., Bracknell, UK). • You can double the current range by installing a second, identical shunt in parallel with the specified 100A shunt. You would then need to recalibrate the meter using the menus, as explained in Pt.2 of the article. Unfortunately, increasing the voltage range is not easy. The meter runs on a 5V rail derived from a switchmode regulator whose maximum input rating is 60V. It would therefore be difficult to increase the voltage range beyond that. Also, the highside amplifiers used are rated at 76V maximum. changes to adapt this circuit to charge a 48V sealed lead-acid battery: (1) Use a transformer made with a 44V winding and a 9V winding. With a bridge rectifier and smoothing capacitor, the DC output from the 44V winding should be close to 62V, enough to take the battery to cut-off. (2) Use the 9V winding, again with a bridge rectifier and smoothing capacitor, to produce 12V to run the control section, with diode D1 deleted. (3) Replace R1 with a 100kΩ resistor to scale down the sensed voltage. Replace the 1.5kΩ resistor for the “Battery” LED with a 2.7kΩ resistor. As the controller will be permanently mounted on the machine, relocate the thermistor to beside the batteries. (T. N., Whenuapai, NZ). • R1 should be 120kΩ for the correct battery voltage division. The LED resistor should be about 4.7kΩ at 1W. Otherwise it should work. Make sure you use a 100V N-channel Mosfet, such as an IRF540N. The IRF1405N is only a 55V device. Chokes for switchmode regulators Can you advise me on how to make a 100µH toroid choke rated at 3-5A? I have been looking at many pages on the web for information regarding details on how to wind the choke but nothing has helped. The toroids are available at Jaycar – Cat. LF1272 (3A) and LF1270 (5A). My concern is whether they are suitable for use with an LM2576 3A switching regulator. (B. B., via email). • Commercial chokes such as the Jaycar ones using ferrite cores are suitable although powdered-iron cores are better as they produce less interference. You can wind your own choke using a powdered-iron core. The inductance depends on the AL value (in nH) of the core. Normally, you use wire that is sufficient for less than 5A per square mm. So a 1mm diameter wire is 0.79 square mm and suited for up to 4A. 1.25mm diameter wire can be used for up to 6A. The calculation for the number of turns = 1000 x square root of inductance L in mH/AL (in nH)) For the Jaycar LO-1246 core, assuming an AL of 120, the number of turns for 100µH is 29 turns. The value Li2 sets the core’s power rating. In this case, 100µH x 5A2 is 2.5mJ. Assuming that the LO-1246 rating is 16mJ, then the core should not saturate. Carbon monoxide alarm heater problem I am building your Carbon Monoxide Monitor (SILICON CHIP, August 2005) and have a problem with the heater control circuit. The voltage at pin 11 of IC1 varies correctly from 5V to a fraction of 1V at regular intervals, however the voltage on the base of Q1, a BC327, varies from 5V to about 4.5V and the transistor does not switch off. As a result, the collector remains at 5V. I have replaced the transistor and still have the same result. Do you have any suggestions please? (G. C., via email). • The 5V to 4.5V base voltage variation for Q1 suggests that the transistor is being switched off (5V at base) and on (4.5V at base). The emitter is at 5V. If the collector remains at 5V, then perhaps there is no heater connection through the CO sensor and the collector is pulled high via the 75Ω and 10Ω series-connected resistors between collector and emitter. Check that there is a connection between the top sensor heater terminal and Q1’s collector and the lower sensor terminal and supply ground. The sensor heater resistance should SC be about 33Ω. 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. 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Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* 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. PRACTICAL GUIDE TO SATELLITE TV 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. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. 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. See Review March 2010 See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Ian Hickman. 4th edition 2007 $61.00* by Douglas Self 2nd Edition 2006 $69.00* by Carl Vogel. Published 2009. $40.00* 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. 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; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK PAYPAL (24/7) INTERNET (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) eMAIL (24/7) FAX (24/7) To ilicon Chip Use your PayPal account www.siliconchip. Call (02) 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 Place100  S com.au/Shop/Books silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details with order & credit card details (02) 9939 2648 with all details Your You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. Order: ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* 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. PRACTICAL GUIDE TO SATELLITE TV 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. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. 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. See Review March 2010 See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Ian Hickman. 4th edition 2007 $61.00* by Douglas Self 2nd Edition 2006 $69.00* by Carl Vogel. Published 2009. $40.00* 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. 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; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK PAYPAL (24/7) INTERNET (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) eMAIL (24/7) FAX (24/7) To siliconchip.com.au eptember 2009  101 Use your PayPal account www.siliconchip. Call (02) 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO BoxS139 Place com.au/Shop/Books silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details with order & credit card details (02) 9939 2648 with all details Your You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. Order: ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP CLASSIFIED ADVERTISING 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). Closing date: 5 weeks prior to month of sale. To book your classified ad, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or fax (02) 9939 2648, or post to Silicon Chip Classifieds, PO Box 139, Collaroy, NSW, Australia 2097. VIDEO - AUDIO - PC distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ MD12 Media Distribution Amplifier QUEST ® Quest AV® VGA Splitter VGS2 _____________ _____________ _____________ _____________ _____________ HQ VGA Cables _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ AWP1 A-V Wallplate Come to the specialists... QUESTRONIX ® Quest Electronics® Pty Limited abn 83 003 501 282 t/a Questronix _____________ _____________ _____________ _____________ _____________ Products, Specials & Pricelist at www.questronix.com.au fax (02) 4341 2795 phone (02) 4343 1970 email: questav<at>questronix.com.au _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ FOR SALE _____________ _____________ _____________ _____________ _____________ 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 _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $­__________ or please debit my o Visa Card   o Master Card Card No. Signature­­­­___­­­­­­­­__________________________ Card expiry date______/______ Name _________________________________________________________ Street _________________________________________________________ Suburb/town ______________________________ Postcode______________ Phone:______________ Fax:______________ Email:___________________ 102  Silicon Chip 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 PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au TECH REPAIRS SERVICE MANUALS www.techrepairs.org – thousands of downloadable service manuals for all siliconchip.com.au SPK360 3/5/06 1:10 PM Page 1 ELNEC IC PROGRAMMERS 20 years experience! High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP HI-FISPEAKER REPAIRS YOUR EXPERT SPEAKER REPAIR SPECIALISTS CLEVERSCOPE USB OSCILLOSCOPES SPK360 Specialising in UK, US and Danish brands. Speakerbits are your vintage, rare and collectable speaker repair experts. Foam surrounds, voice coils, complete recone kits and more. Original OEM parts for Scan-Speak, Dynaudio, Tannoy, JBL, ElectroVoice and others! tel: 03 9647 7000 www.speakerbits.com C O N T R O L S Tough times demand innovative solutions! 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 Normally 98 SILICON CHIP reader price: $ 88 Av-Comm Pty Ltd 24/9 Powells Rd, Brookvale NSW (PO Box 225, Brookvale NSW 2100) Phone: 02 9939 4377 Fax: 02 9939 4376 Email: michael<at>avcomm.com.au • Learn about engine management systems From the publis hers of • Projects to control nitrous, fuel injection and turbo boost systems • Switch devices on and off according to signal frequency, temp­erature & voltage Intelligent turbo timer • Build test instruments to check fuel injector duty cycle, fuel I SBN 0958522 94 -4 TURBO BO OST & nitrous fuel cont 9 78095 8 5229 46 $19.80 (inc GST) NZ $22.00 (inc GST) rollers How engine management works Price: Aust. $A19.80 plus $A10 P&P ($A12 P&P NZ; $A18 P&P elsewhere) – see the order form in this issue or www.siliconchip.com.au for ordering details. siliconchip.com.au $ (inc P&H Aust wide) Only from the communications specialists: Looking for real performance? WANTED: EARLY HIFIs, AMPLIFIERS, Speakers, Turntables, Valves, Books, Quad, Leak, Pye, Lowther, Ortofon, SME, Western Electric, Altec, Marantz, McIntosh, Tannoy, Goodmans, Wharfedale, radio and wireless. Collector/ Hobbyist will pay cash. (07) 5471 1062. johnmurt<at>highprofile.com.au Tecsun PL300 DSP Receiver GRANTRONICS PTY LTD splat-sc.com WANTED Cat Q-3048 ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 IMAGECRAFT C COMPILERS Made in Australia, used by OEMs world-wide brands, makes and models including PDP, LCD, VCR, DVD, CTV, Vintage Radio, Laptops, Monitors, Vacuum Cleaners, Washing Machines, Dryers, Fridges and many more. An absolute must have website for any Tech! : t Sized Pockejust m x26m 135x86350g! & special offer for silicon chip readers! Enjoy optimum sensitivity and selectivity with Digital Signal Processing (DSP)! FM: 64 - 108MHz MW/LW: 153 - 1710kHz SW: 3.15 - 21.95MHz (1kHz steps) LCD readout, 500 memory positions, 24 Hour Digital clock, Battery/external DC www.grantronics.com.au mixtures and brake & temperature 10% NT! U O C S DI CUSTOMERS WANTED: Truscotts Electronic World – large range of semiconductors and passive components for industry, hobbyist and amateur projects including Drew Diamond. 27 The Mall, South Croydon, Melbourne. (03) 9723 3860. electronicworld<at>optusnet. com.au KIT ASSEMBLY KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com Silicon Chip Binders REAL VALUE AT $14.95 PLUS P & P H SILICON CHIP logo printed on spine & cover H Buy five and get them postage free! Price: $A14.95 plus $10.00 p&p per order. Available only in Aust. Silicon Chip Publications, PO Box 139, Collaroy 2097 Fax (02) 9939 2648 or phone (02) 9939 3295 & quote your credit card number. September 2009  103 Do you eat, breathe and sleep TECHNOLOGY? Opportunities exist for experienced Sales Professionals & Store Management across Australia & NZ Jaycar Electronics is a rapidly growing, Australian owned, international retailer with more than 60 stores in Australia and New Zealand. Due to our aggressive expansion program we are seeking dedicated sales professionals to join our retail team to assist us in achieving our goals. 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..................................... 78-81 Av-Comm...................................... 103 Dick Smith Electronics............... 24-25 Emona Instruments......................... 59 Farnell..........................................OBC Futurlec........................................... 10 Grantronics................................... 103 High Profile Communications........ 103 Instant PCBs................................. 103 Jaycar............................IFC,49-56,104 Keith Rippon................................. 103 LED Sales..................................... 102 MicroZed Computers...................... 74 Mornsun.......................................... 71 Oatley Electronics......................... IBC Ocean Controls................................. 8 Ozitronics........................................ 95 PCBCART....................................... 11 PCBCORE........................................ 9 Quest Electronics.......................... 102 RCS Radio.................................... 102 into RF? DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom There’s something to suit every radio frequency fan in the SILICON CHIP reference bookshop RF Circuit Design – by Chris Bowick A new edition of this classic RF design text - tells how to design and integrate RF components into virtually any circuitry. $ 75 Practical RF H’book – by Ian Hickman A reference work for technicians, engineers, students and the more specialised enthusiast. Covers all the key topics in RF that you $ need to understand 90 Practical Guide To Satellite TV – by Garry Cratt The reference written by an Aussie for Aussie conditions.Everything you need to know. $ 49 You’ll find many more technical titles in the SILICON CHIP reference bookshop – see elsewhere in this issue 104  Silicon Chip WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au Silicon Chip Circuit Ideas Wanted Do you have a good circuit idea? If so, sketch it out, write a brief description of its operation & send it to us. Provided your idea is workable & original, we’ll publish it in Circuit Notebook & you’ll make some money. We pay up to $100 for a good circuit idea or you could win some test gear. Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. RF Modules................................ 3,104 RMS Parts....................................... 37 SabTec.............................................. 5 Sesame Electronics...................... 102 Silicon Chip Binders...................... 103 Silicon Chip Bookshop........... 100-101 SC Performance Elect. For Cars... 104 Silicon Chip Order Form................. 99 Silicon Chip Subscriptions.............. 93 Siomar Battery Industries................. 7 Soundlabs Group............................ 57 Speakerbits................................... 103 Splat Controls............................... 103 Tech Repairs................................. 102 Truscotts Electronic World............. 103 Wagner Electronics......................... 61 Worldwide Elect. Components...... 104 PC Boards Printed circuit boards for SILICON CHIP designs can be obtained from RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0331. siliconchip.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.oatleyelectronics.com.au