ROLLING CODE KEYLESS ENTRY SYSTEM Up to 16 keyfob transmitters Two door-strike outputs High security Alarm system
RECYCLE IT A low-cost large-display anemometer from recycled parts FAST CHARGER FOR NiMH BATTERIES A versatile, safe charger to suit any size cells
PLUS $8.75 US $10.25 CAN BREADBOARDING PROJECTS AUGUST 2009 PRINTED IN THE UK Festive Lights Copyright Ó 2008, Wimborne Publishing Ltd (Sequoia House, 398a Ringwood Road, Ferndown, Dorset BH22 9AU, UK)
and TechBites Interactive Inc., (PO Box 857, Madison, Alabama 35758, USA)
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Because of possible variances in the quality and condition of materials and workmanship used by readers, EPE Online, its publishers and agents disclaim any responsibility for the safe and proper functioning of reader-constructed projects based on or from information published in these materials and works. In no event shall TechBites Interactive Inc or Wimborne Publishing Ltd be responsible or liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or any other damages in connection with or arising out of furnishing, performance, or use of these materials and works. ISSN 0262 3617 PROJECTS THEORY NEWS COMMENT POPULAR FEATURES INCORPORATING ELECTRONICS TODAY INTERNATIONAL VOL. 38. No 8 August 2009 www.epemag.com
Projects and Circuits ROLLING CODE KEYLESS ENTRY SYSTEM – PART 1 by John Clarke 10 Rolling code makes it super secure. Can respond to up to 16 keyfob transmitters SIMPLE DATA-LOGGING WEATHER STATION – PART 2 by Glenn Pure 24 Records rainfall and temperature, and operates completely unattended FAST CHARGER FOR NiMH BATTERIES by John Clarke 36 Can charge up to 15 identical NiMH or NiCad cells BREADBOARDING PROJECTS by Dr Malcolm Plant 56 Part 11 – Festive Lights INGENUITY UNLIMITED 62 Optical Motion Detector Series and Features TECHNO TALK by Mark Nelson 22 Diatomic power RECYCLE IT by Julian Edgar 48 A low-cost large-display anemometer INTERFACE by Robert Penfold 60 Calculated connection CIRCUIT SURGERY by Ian Bell 64 Filter circuits – Part 2 PIC N’ MIX by Mike Hibbett 68 PIC RS232 terminal NET WORK by Alan Winstanley 74 The more things change; A plateful of spam Regulars and Services EDITORIAL 7 NEWS – Barry Fox highlights technology’s leading edge 8 Plus everyday news from the world of electronics ELECTRONICS TEACH-IN 2 23 New book with Free CD-ROM – Using PIC Microcontrollers BACK ISSUES Did you miss these? 34 PIC PROJECTS CD-ROM 46 A plethora of handPICed projects PIC RESOURCES CD-ROM 47 EPE PIC Tutorial V2, plus PIC Toolkit Mk3 and a selection of PIC-related articles SUBSCRIBE TO EPE and save money 55 ELECTRONICS MANUALS 59 The Modern Electronics Manual and Electronic Service Manual on CD-ROM CD-ROMS FOR ELECTRONICS 70 A wide range of CD-ROMs for hobbyists, students and engineers READOUT Matt Pulzer addresses general points arising 73 DIRECT BOOK SERVICE 75 A wide range of technical books available by mail order, plus more CD-ROMs © Wimborne Publishing Ltd 2009. Copyright in all EPE PCB SERVICE 78 drawings, photographs and articles published in EVERYDAY PRACTICAL ELECTRONICS is fully ADVERTISERS INDEX 80 protected, and reproduction or imitations in whole or in part are expressly forbidden.
Our September 2009 issue will be published on Thursday 13 August 2009, see page 80 for details.
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%%%1%% %'% %/% %1% % %/% % % Everyday Practical Electronics Magazine has been publishing a series of popular kits by the acclaimed Silicon Chip Magazine Australia. These projects are 'bullet proof' and already tested down under. All Jaycar kits are supplied with specified board components, quality fibreglass tinned PCBs and August ‘09 have clear English instructions. Watch this space for future featured kits.
FAST NI-MH BATTERY PIC LOGIC PROBE KIT CHARGER KIT KC-5457 £5.00 + KC-5453 £12.50 plus postage & packing post & packing A truly versatile charger, capable of handling up to 15 of the same type of Ni-MH or Ni-Cd cells. Build it to suit any size cells or cell capacity and set your own fast or trickle charge rate. It also has overcharge protection including temperature sensing. Ideal for RC enthusiasts who burn through a lot of batteries. Kit includes NEW solder mask & overlay PCB, programmed micro and all specified TO EPE NEW electronic components. Case, heatsink and battery holder not included. TO EPE Operating on 2.8 to 15VDC, this logic probe is suitable for use on the most modern circuits. It's also As published in EPE August 2009 extremely compact with SMT devices on a PCB only 5mm wide, so it will fit inside a very slim case. It's capable of picking up a pulse only 50mS long and will also detect and SMS CONTROLLER STUDIO 350 - HIGH hold infrequent pulses when in latch mode. Kit includes PCB MODULE KIT POWER AMPLIFIER KIT and all specified electronic components including pre- KC-5400 £17.00 plus postage & packing KC-5372 £50.75 plus postage & packing programmed PIC. You'll need to add your own case and probe - a clear ballpoint pen and a darning needle work well. Control appliances or receive alert notification from anywhere. Studio quality sound and distortion with tremendous power By sending plain text messages this kit will allow you to control output. This will deliver a whopping 350WRMS into 4 ohms, As published in EPE Magazine July 2009 up to eight devices. At the same time, it can also monitor four or 200WRMS into 8 ohms. Using eight 250V 200W plastic digital inputs. It works with old Nokia handsets such as the power transistors, it is super quiet, with a signal to noise ratio 5110, 6110, 3210, and 3310, which can be bought of -125dB(A) at full 8 ohm power. Harmonic distortion is just inexpensively. Kit supplied with PCB, pre-programmed 0.002%, and frequency response is almost flat (less than - GALACTIC microcontroller and all electronics components 1dB) between 15Hz and 60kHz! Kit supplied in short form VOICE KIT with manual. Requires a Nokia with PCB & electronic components. data cable which can KC-5431 £13.50 plus postage & packing be readily found in Be the envy of everyone at the next Interplanetary Conference mobile phone with this galactic voice simulator kit. Effect and depth controls accessory stores. allow you to simulate everything from the metallically-endowed As published in C-3PO, to the hysterical EPE March 2007 As published in ranting of the Daleks. The EPE Oct/Nov 2006 kit includes PCB with overlay, enclosure, speaker LED WATER LEVEL and all components. INDICATOR KIT - MKII VOLTAGE As published in EPE August 2008 KC-5449 £11.75 plus MONITOR KIT postage & packing This simple circuit illuminates a string KC-5424 £6.75 plus of LEDs to quickly indicate the water postage & packing level in a rainwater tank. The more This versatile kit will allow you to monitor the 3V TO 9V DC TO DC LEDs that illuminate, the higher the water battery voltage, the airflow meter or oxygen sensor in your car. It CONVERTER KIT has a 10 LED bar graph that lights in response to the measured level is inside the tank. The input signal is KC-5391 £4.75 plus postage & packing provided by ten sensors located in the voltage, preset 9-16V, 0.-5V and 0-1V range. Features a fast This enables you to use regular Ni-Cd or Ni-MH 1.2V cells, or water tank and connected to the indicator unit via-light duty response time, high input impedance and auto dimming for Alkaline 1.5V cells for 9V applications. Using low cost, high figure-8 cable. Kit supplied with PCB with overlay, machined night time driving. Kit includes PCB with overlay, LED bar graph capacity rechargeable cells, this kit will pay for itself in no- case with screenprinted lid and all electronic components. and all electronic components. t7%$ time! Imagine the extra capacity you can have using two 9000mAh D cells instead of a low capacity 9V cell. Kit t3FRVJSFTNN 0% 17$IPTFQJQF MFOHUISFRVJSFE supplied with PCB, and all depending on depth of tank) As published in EPE November 2007 electronic components. t3FRVJSFT7"$PS%$QMVHQBDL As published As published in EPE March 2009 COURTESY INTERIOR LIGHT DELAY KIT in EPE June 2007 KC-5392 £6.00 plus postage & packing THE Many modern cars feature a time delay on the interior light, 'FLEXITIMER' KIT allowing driver and passengers time to buckle up and get organised before the light dims and finally goes out. This kit KA-1732 £6.00 plus postage & packing enables your car to have the same handy feature, with a soft t4FDVSFPOMJOFPSEFSJOH Uses a handful of components to fade out after a set time has elapsed, and much simpler t"--QSJDFTJO1PVOET4UFSMJOH accurately time intervals from a universal wiring than previous models we have had. t.JOJNVNPSEFS0/-:b few seconds to a whole day. It Suitable for circuits switching ground or +12V or 24VDC can switch a number of (car & truck with negative chassis) different output devices on and off at timed intervals. t,JUTVQQMJFEXJUI1$# PWFSMBZ ORDER YOUR Powered by a battery or & all electronic components FREE mains plugpack, this kit includes CATALOGUE PCB and all components. As published in TODAY! EPE February 2007 As published in EPE September 2007
0800 032 7241 jaycarelectronics.co.uk
&.&3(&/$:7 '3&26&/$: -*()5*/($0/530--&3 .&5&3,*5.,** KC-5456 £20.50 plus KC-5440 £20.50 plus postage & packing 4&3*"- postage & packing This compact and 130(3"..&3,*5 Automatically supplies power for 12V emergency lighting during low cost a blackout. The system is powered with a 7.5Ah SLA battery 50MHz KC-5467 £21.75 plus postage & packing which is maintained via an external smart charger. Includes frequency This very cost effective programmer kit can handle all the manual override and over-discharge protection for the battery. meter is %41*$'GBNJMZPG1*$NJDSPDPOUSPMMFSTBOEBMNPTUBMMPGUIF Kit supplied with all electronic components, screen printed PCB, invaluable for regular PICs available in a DIP package. It uses freely available front panel and case. Charger and SLA battery servicing and software for PCs and is easy to build. available separately. diagnostics. Microchip offers free This upgraded documentation and source version features code on their website an automatic indication of so getting started units (Hz, kHz, MHz or GHz) and prescaler. Kit should be a includes PCB with overlay, enclosure, LCD and all breeze. electronic components. Supplied with screen printed PCB, 2 x t1PXFSFECZY"""CBUUFSJFTPS%$QMVHQBDL 40 pin ZIF sockets and all specified components.
'-*$,&3*/('-".& 53"/4*4503 -*()5*/(,*5 5&45&3,*5 KC-5234 £5 plus postage & packing KA-1119 £8.25 plus 7-*()501&3"5&% This lighting effect uses a single 20 postage & packing 3&-":,*5 watt halogen lamp to mimic it's Have you ever unsoldered a suspect namesake. Mounted on a transistor only to find that it checks OK? KG-9090 £7.25 plus compact PCB, it operates Avoid these hassles with this in-circuit postage & packing from 12VDC and uses just a transistor, SCR and diode tester. The kit This kit can operate as a handful of readily available XJMM UFTUESJWFT8*5)065UIFOFFE twilight on/off switch or as components. Use it for stage to unsolder them from the circuit! a light trigger relay. performances or for unique Includes a jiffy box, battery, electronic Operated from 12 volts, lighting effects at home. components, and panel showing truth table for device checking. this versatile project triggers a 6 amp relay t*ODMVEFT8IBMPHFOMBNQ when the light intensity falls below an PCB plus electronic components -69&0/45"3 adjustable threshold. Turn lights on around the t/PXJODMVEFT4-DFSBNJDCBTF -&%%3*7&3,*5 house when it goes dark or trigger an alarm when a light is switched on. Kit supplied with Kwik Kit PCB, relay and all KC-5389 £8.75 plus electronic components. postage & packing %*(*5"- Extremely bright & efficient, Luxeon high .6-5*.&5&3,*5 power LEDs offer up to 120 lumens per unit, /&0/56#&406/% and will last up to 100,000 hours! This kit allows you to KG-9250 £7.25 plus postage & packing QPXFSUIFGBOUBTUJD8 8 BOE8-VYFPO4UBS-&%TGSPN %*41-":,*5 12VDC. Use them in your car, boat, or caravan. Kit supplied with Learn everything there is to know about component recognition PCB, and all electronic components. KC-5322 £6.00 plus postage & packing and basic electronics with this This kit drives any colour neon tube in the Jaycar range and has comprehensive kit. From XBUU-&%TUBSNPEVMFTBWBJMBCMFJOBSBOHFPGDPMPVSTb the option of turning the tube either on or off to the beat of the test leads to solder, ZD-0500 - Red; ZD-0502 - Amber; ZD-0504 - NVTJD8JUIUIJTMBUFTULJUZPVDBOOPXVTFBOZPVUQVUGSPNZPVS everything you need for (SFFO ;%#MVF ;%8BSN8IJUF car stereo - unlike its predecessor it is not the construction of this limited to being exclusively driven by a meter is included. All subwoofer output. Kit supplied you'll need is a FREE CATALOGUE with PCB plus all soldering iron! specified electronic Checkout Jaycar’s components. t.FUFSEJNFOTJPOT 8 Y ) Y extensive range 25(D)mm We have kits & electronic projects for use in: t"VEJP7JEFP HOW TO ORDER t$BS"VUPNPUJWF 10451"$,*/($)"3(&4 t$PNQVUFS t-JHIUJOH Order Value Cost t 03%&30/-*/&XXXKBZDBSFMFDUSPOJDTDPVL t1PXFS t5FTU.FUFST £10 - £49.99 £5 Max weight 12lb (5kg). t1)0/& 0800 032 7241* t-FBSOJOH&EVDBUJPOBM £50 - £99.99 £10 Heavier parcels POA. t'"9 +61 2 8832 3118* t(FOFSBM&MFDUSPOJDT1SPKFDUT £100 - £199.99 £20 t&."*-[email protected] Minimum order £10. t(JGUT (BEHFUT+VTUGPSGVO £200 - £499.99 £30 t104510#PY 3ZEBMNFSF/48"VTUSBMJB For your FREE catalogue log on to: £500+ £40 t "--13*$*/(*/106/%445&3-*/( t .*/*.6.03%&30/-:b XXXKBZDBSFMFDUSPOJDTDPVLDBUBMPHVF Note: Products are despatched from Australia, *Australian Eastern Standard Time (Monday - Friday or check out the range at: so local customs duty & taxes may apply. 09.00 to 17.30 GMT + 10 hours only) Prices valid until 31/8/09 XXXKBZDBSFMFDUSPOJDTDPVL Expect 10-14 days for air parcel delivery
0800 032 7241 jaycarelectronics.co.uk 4000 Series 74HC153 £0.30 74LS266 £0.14 OP200GP £5.60 Diodes Thyristors BC209A £0.72 BFY51 £0.22 ZTX951 £0.54 4000B £0.27 74HC154 £0.94 74LS273 £0.32 OP275GP £2.57 1N914 £0.05 2N5060 £0.19 BC212L £0.09 BFY52 £0.32 ZTX1048A £0.48 4001B £0.16 74HC157 £0.22 74LS279 £0.24 OP282GP £2.27 1N4001 £0.04 2N5061 £0.19 BC214 £0.11 BS107 £0.21 ZTX1051A £0.46 4002B £0.19 74HC158 £0.23 74LS283 £0.47 OP283GP £5.20 1N4002 £0.05 BT151-500R £0.65 BC214L £0.10 BS170 £0.15 ZTX1053A £0.45 4006B £0.65 74HC161 £0.27 74LS365 £0.21 OP290GP £4.28 1N4003 £0.03 PO102AA £0.30 BC225 £0.15 BU208A £1.53 4009UB £0.23 74HC162 £0.45 74LS367 £0.21 OP297GP £4.64 1N4004 £0.04 TIC106D £0.60 BC237B £0.11 BU326A £1.40 BC238B £0.11 BU500 £1.54 NOW ONLINE 4010B £0.23 74HC163 £0.26 74LS368 £0.21 OP400GP £11.81 1N4005 £0.04 TIC116D £0.66 Transformers 4011B £0.16 74HC164 £0.20 74LS373 £0.39 OP495GP £8.69 1N4006 £0.04 TIC126D £0.77 BC250A £0.15 BU508A £1.40 1N4007 £0.03 BC261B £0.30 BU508D £0.98 Large selection 4012B £0.16 74HC165 £0.21 74LS374 £0.38 RC4136 £1.00 of mains & 4013B £0.18 74HC173 £0.38 74LS378 £0.62 SG3524N £0.82 1N4148 £0.03 Triacs BC262B £0.24 BU806 £1.06 1N4149 £0.07 BC267B £0.36 BUT11AF £1.14 audioaudio 4014B £0.30 74HC174 £0.27 74LS390 £0.34 SG3543 £6.88 BT136-500 £0.58 transformers.tranaannsforsfoormersm . 4015B £0.27 74HC175 £0.35 74LS393 £0.33 SSM2141P £3.21 1N5400 £0.08 BT136-600 £0.50 BC319C £0.13 BUX84 £0.78 4016B £0.20 74HC193 £0.39 74LS395 £0.26 SSM2142P £6.16 1N5401 £0.08 BT137-600 £0.58 BC327 £0.08 BUZ900 £7.68 4017B £0.26 74HC195 £0.32 SSM2143P £3.78 1N5402 £0.08 BT139-500 £1.00 BC327-25 £0.08 BUZ900P £5.74 74 Series 1N5404 £0.09 BC328 £0.09 BUZ905 £7.68 4018B £0.25 74HC240 £0.32 7407 £0.40 TBA120S £1.04 BT139-600 £1.20 4019B £0.25 74HC241 £0.37 TBA800 £0.75 1N5406 £0.10 BTA08-600B £0.84 BC337-16 £0.10 BUZ905P £5.55 Linear ICs 1N5407 £0.10 BC337-25 £0.08 IRF530 £0.75 4020B £0.25 74HC244 £0.40 TBA820M £0.53 BTA08-600BW£0.76 FusesFuses 4021B £0.22 74HC245 £0.34 AD524AD £23.04 1N5408 £0.10 BTA08-600C £0.96 BC348B £0.14 IRF540 £0.78 TDA1170S £4.80 BC357 £0.25 IRF630 £0.42 20mm, 32mm 4022B £0.38 74HC251 £0.30 AD548JN £2.48 6A05 £0.27 BTA08-600SW£0.93 TDA2004 £2.24 BC393 £0.73 Quick Blow & 4023B £0.23 AD590JH £5.28 6A1 £0.30 BTA08-600TW£1.10 IRF640 £0.72 74HC253 £0.25 TDA2003V £1.25 BC461 £0.41 IRF730 £0.66 Time-lag 4024B £0.22 AD595AQ £13.92 6A2 £0.27 BTA12-600BW£0.92 74HC257 £0.25 TDA2030AV £1.24 BC463 £0.29 IRF740 £0.91 Glass, Ceramic 4025B £0.20 74HC259 £0.29 AD620AN £9.88 TDA2050V £2.51 6A4 £0.28 BTA16-600CW £1.45 4026B £0.67 74HC273 £0.32 AD625JN £16.20 TDA2611A £1.88 6A6 £0.32 BTA16-600B £1.28 BC477 £0.52 IRF830 £0.68 4027B £0.21 AD633JN £5.93 6A8 £0.30 BTA26-600B £2.78 BC479 £0.32 IRF840 £0.78 74HC299 £0.61 TDA2822A £0.79 6A10 £0.35 BC516 £0.21 MJ2955 £0.90 4028B £0.21 74HC365 £0.28 AD648JN £2.57 TDA2653A £2.99 TIC206D £0.84 www.esr.co.uk AD654JN £5.51 BA157 £0.07 TIC206M £0.75 BC517 £0.14 MJ2501 £1.60 4029B £0.38 74HC367 £0.38 TED3718DP £5.03 BA159 £0.13 BC546B £0.06 MJ3001 £1.84 4030B £0.17 74HC368 £0.29 AD711JN £1.97 TEA5115 £3.11 TIC226D £0.80 AD712JN £2.51 BAT41 £0.12 TIC226M £1.00 BC546C £0.08 MJ11015 £2.45 4035B £0.31 74HC373 £0.35 TL061CP £0.21 BAT42 £0.07 BC547A £0.09 MJ11016 £2.78 4040B £0.24 74HC374 £0.34 AD736JN £5.80 TL062CP £0.21 TIC246D £1.00 AD797AN £7.25 BAT46 £0.12 TIC246M £1.00 BC547B £0.09 MJE340 £0.33 On the WEB 4041B £0.31 74HC390 £0.37 TL064CN £0.29 BAT85 £0.09 BC547C £0.10 MJE350 £0.32 Check out our 4042B £0.19 74HC393 £0.36 AD811N £6.00 TL071CN £0.30 TIC236D £1.12 web site with AD812AN £6.32 BAV21 £0.07 BC548A £0.08 MPSA05 £0.14 more products 4043B £0.35 74HC563 £0.56 TL072CN £0.20 BAW62 £0.07 BC548B £0.09 MPSA13 £0.09 4046B £0.42 74HC573 £0.27 AD820AN £3.41 TL074CN £0.25 Diac than ever before. AD822AN £5.20 BAX16 £0.05 BC548C £0.08 MPSA42 £0.14 4047B £0.25 74HC574 £0.30 TL081CN £0.17 BY127 £0.18 DB3, 32V £0.08 BC549B £0.09 MPSA55 £0.13 Components 4048B £0.34 74HC595 £0.27 AD829JN £6.41 TL082CN £0.32 Connectors AD830AN £5.44 BY133 £0.10 Transistors BC549C £0.09 MPSA56 £0.12 Cable 4049B £0.29 74HC597 £0.22 TL084CN £0.37 OA91 £0.32 2N2222A £0.23 BC550C £0.11 STP14NF10 £0.49 4049UB £0.17 74HC688 £0.46 AD847JN £5.95 TL7705ACP £0.82 CCTV AD9696KN £7.73 OA200 £0.56 2N2646 £1.02 BC556A £0.08 STW80NE-10 £3.80 Enclosures 4050B £0.20 74HC4002 £0.31 TLC271 £0.63 UF4001 £0.08 2N2904A £0.35 BC556B £0.10 TIP29A £0.32 4051B £0.23 74HC4017 £0.24 ADEL2020A £5.06 TS272CN £0.57 Fans & Heat- ADM222AH £3.55 UF4002 £0.08 2N2905A £0.30 BC557A £0.09 TIP29C £0.33 sinks 4052B £0.32 74HC4020 £0.36 TS274CN £0.50 UF4003 £0.09 2N2907A £0.28 BC557B £0.09 TIP30A £0.47 4053B £0.20 74HC4040 £0.29 ADM232AA £3.55 TS555CN £0.26 BC557C £0.09 TIP30C £0.27 Fuses ADM485JN £2.97 UF4004 £0.08 2N3053 £0.38 Hardware 4054B £0.56 74HC4049 £0.31 TMP01FP £5.60 UF4005 £0.10 2N3054 £0.85 BC558A £0.08 TIP31A £0.23 4055B £0.34 74HC4051 £0.50 ADM666AN £2.72 UA741CN £0.18 BC558B £0.09 TIP31C £0.35 Lamps ADM690AN £5.13 UF4006 £0.10 2N3055 £0.62 Leads 4060B £0.17 74HC4052 £0.34 ULN2003A £0.38 UF4007 £0.14 2N3439 £0.62 BC559A £0.08 TIP32A £0.29 4063B £0.41 74HC4053 £0.22 ADM691AN £6.48 ULN2004A £0.44 Zeners 2.7 to 33V BC560B £0.13 TIP32C £0.30 PCB Equipment ADM695AN £6.48 2N3440 £0.50 Power Supplies 4066B £0.17 74HC4060 £0.23 ULN2803A £0.45 500mW £0.06 2N3702 £0.09 BC636 £0.10 TIP33C £0.74 4067B £2.20 74HC4075 £0.27 ADM699AN £3.58 ULN2804A £0.41 1.3W £0.10 BC637 £0.19 TIP41A £0.32 Relays CA3046 £0.65 2N3703 £0.10 Soldering 4068B £0.19 74HC4078 £0.32 EPROM’s Bridge Rectifiers 2N3704 £0.11 BC638 £0.21 TIP41C £0.32 Sounders 4069UB £0.18 74HC4511 £0.64 CA3130E £0.87 BC639 £0.09 TIP42A £0.47 CA3140E £0.63 24LC08BP £0.73 1A 50V £0.35 2N3705 £0.08 Switches 4070B £0.15 74HC4514 £0.84 24LC16BP £0.69 1A 100V £0.32 2N3772 £1.72 BC640 £0.12 TIP42C £0.43 Test Equipment 4071B £0.20 74HC4538 £0.41 CA3240E £0.91 2N3773 £1.91 BCY72 £0.20 TIP50 £0.28 DG211CJ £1.25 27128-200 £3.99 1A 200V £0.39 Tools 4072B £0.25 74HC4543 £0.90 27256-200 £3.99 1A 600V £0.40 2N3819 £0.20 BD124P £6.86 TIP110 £0.28 Transformers 4073B £0.17 DG411DJ £2.00 2N3903 £0.11 BD131 £0.48 TIP120 £0.30 and more 74LS Series ICL7106CPL £2.21 27C64A-15F £3.99 1A 800V £0.43 4075B £0.17 74LS00 £0.38 27C256B-15F £3.00 1.5A 50V £0.19 2N3904 £0.05 BD132 £0.46 TIP121 £0.32 4076B £0.30 ICL7107CPL £2.06 2N3905 £0.10 BD135 £0.22 TIP122 £0.37 74LS01 £0.14 ICL7109CLP £5.76 27C1001-15. £3.98 1.5A 100V £0.11 4075B £0.15 74LS02 £0.22 27C2001-15. £4.41 1.5A 200V £0.19 2N4401 £0.08 BD136 £0.21 TIP125 £0.31 4077B £0.28 ICL7611DCP £1.00 27C4001-10F£5.98 1.5A 400V £0.20 2N4403 £0.09 BD137 £0.23 TIP126 £0.31 74LS03 £0.21 ICL7621 £0.84 BD138 £0.19 TIP127 £0.37 Quality 4078B £0.30 74LS04 £0.30 93C46N £0.28 1.5A 600V £0.24 2N5245 £0.80 Components 4081B £0.13 ICL7660SCP £0.80 1.5A 800V £0.26 2N5296 £0.57 BD139 £0.19 TIP132 £0.50 74LS05 £0.14 ICM7555 £0.48 RAM BD140 £0.14 TIP137 £0.64 No surplus or 4082B £0.21 74LS08 £0.19 1.5A 1kV £0.18 2N5401 £0.12 4085B £0.28 ICM7556 £1.04 GM76C88. £3.60 2N5551 £0.07 BD150C £0.82 TIP141 £0.93 redundant stock. 74LS09 £0.15 2A 100V £0.34 All from leading 4086B £0.33 L165V £2.26 A/D Converters 2A 200V £0.34 2N6491 £1.58 BD201 £0.40 TIP142 £0.93 74LS10 £0.27 L272M £1.21 Data Acquisi- BD202 £0.70 TIP147 £1.07 manufactures. 4093B £0.16 74LS11 £0.17 2A 400V £0.35 2N7000 £0.12 4094B £0.29 L293E £4.20 tion 2A 800V £0.36 2SB548 £0.30 BD232 £0.50 TIP2955 £0.46 74LS12 £0.25 L297 £5.12 AD420AN £25.38 AC187 £0.68 BD237 £0.32 TIP3055 £0.58 Quality 4098B £0.40 74LS14 £0.36 2A 1000V £0.45 Service 4099B £0.35 L298N £3.80 AD7528JN £11.42 3A 200V £0.34 ACY17 £4.84 BD238 £0.44 ZVN2106A £0.40 74LS15 £0.24 L4960 £2.81 AD7545AK £14.04 AD149 £1.29 BD240C £0.37 ZVN3306A £0.30 Sameday des- 4502B £0.32 74LS20 £0.27 3A 400V £0.40 4503B £0.40 L6219 £4.48 AD7828KN £20.33 3A 600V £0.33 AD161 £0.73 BD245C £1.10 ZVN4206A £0.52 patch on all 74LS21 £0.20 LF347N £0.41 DAC0800 £2.40 AD162 £0.95 BD246C £1.18 ZVN4210A £0.56 stock items. 4508B £1.40 74LS26 £0.17 3A 1000V £0.33 4510B £0.45 LF351N £0.44 ICL7109CPL £7.75 4A 100V £0.78 BC107 £0.18 BD283 £0.61 ZVN4306A £0.74 Friendly helpful 74LS27 £0.25 LF353N £0.40 u BC107B £0.14 BD284 £0.61 ZVN4310A £0.88 staff. 4511B £0.36 74LS30 £0.20 Controllers 4A 200V £0.80 4512B £0.27 LF356 £0.52 AT89C2051 £6.38 4A 400V £0.86 BC108 £0.18 BD400 £0.79 ZVP2106A £0.42 74LS32 £0.23 LF411CN £1.00 BC108B £0.14 BD437 £0.17 ZVP2110A £0.46 Fast Delivery 4515B £0.99 74LS37 £0.31 PIC Series 4A 600V £0.90 4516B £0.44 LM311N8 £0.17 6A 100V £0.49 BC108C £0.18 BD438 £0.22 ZVP3306A £0.32 Nextday service 74LS38 £0.18 12C508A04P £0.78 BC109 £0.19 BD442 £0.37 ZTX302 £0.17 for all orders at 4518B £0.42 LM319N14 £0.90 12C509A04P £0.83 6A 200V £0.64 74LS40 £0.14 LM324 £0.20 6A 400V £0.53 BC109C £0.16 BD534 £0.47 ZTX450 £0.19 no extra charge. 4520B £0.34 74LS51 £0.24 16C54C04P £1.49 BD535 £0.50 ZTX451 £0.21 4521B £0.68 LM335Z £1.12 6A 600V £0.67 BC114 £0.19 74LS83 £0.38 LM339N £0.18 16C54BJW £7.60 6A 800V £0.37 BC115 £0.41 BD646 £0.52 ZTX453 £0.26 No Minimum 4526B £0.40 74LS85 £0.48 BD648 £0.52 ZTX502 £0.17 4527B £0.40 LM348N £0.36 16C56A-04P £1.56 8A 100V £0.98 BC118 £0.41 Order 74LS86 £0.25 LM35DZ £1.37 16F84-04P £3.14 8A 200V £1.00 BC132 £0.36 BDX32 £1.78 ZTX550 £0.22 Order what you 4529B £0.44 74LS92 £0.45 BDX53C £0.53 ZTX551 £0.33 4532B £0.24 LM358N £0.13 16F84-10P £4.16 8A 400V £1.20 BC134 £0.36 need, no pack 74LS93 £0.58 LM380N £0.90 16F627-04P £1.65 8A 600V £1.33 BC135 £0.36 BDX54C £0.50 ZTX600 £0.33 quantities or min 4536B £1.00 74LS107 £0.30 BF180 £0.31 ZTX600B £0.35 4538B £0.26 LM386 £0.50 16F627-20IP £1.80 8A 1000V £1.05 BC142 £0.50 order value. 74LS109 £0.21 LM392N £1.10 25A 100V £1.47 BC159 £0.17 BF182 £0.31 ZTX605 £0.36 4541B £0.33 74LS112 £0.24 17F628-20IP £2.40 BC160 £0.28 BF245B £0.40 ZTX651 £0.33 4543B £0.47 LM393N £0.21 16F867-04SP £5.10 25A 200V £1.54 Quantity 74LS113 £0.23 LM1881 £2.90 25A 400V £1.98 BC170B £0.16 BF257 £0.33 ZTX653 £0.37 Discounts 4555B £0.32 74LS114 £0.36 16F877-20P £5.79 BF259 £0.33 ZTX689B £0.40 4556B £0.40 LM2901N £0.15 25A 600V £1.82 BC177 £0.25 Available 74LS122 £0.31 LM2917N8 £1.98 Voltage 35A 100V £1.57 BC178 £0.18 BF337 £0.40 ZTX690B £0.37 We offer dis- 4584B £0.33 74LS123 £0.31 Regulators BC179 £0.15 BF422 £0.15 ZTX705 £0.39 4585B £0.47 LM3900N £0.72 35A 200V £1.80 counts for all 74LS125 £0.28 LM3914 £1.90 7805 £0.27 35A 400V £1.44 BC182B £0.09 BF423 £0.15 ZTX750 £0.25 items subject to 4724B £0.94 74LS126 £0.25 7806 £0.29 BC182L £0.11 BF459 £0.33 ZTX751 £0.34 40106B £0.19 LM3915 £2.24 35A 600V £1.90 quantity re- 74LS132 £0.47 7808 £0.27 35A 1000V £2.32 BC183L £0.09 BF469 £0.36 ZTX753 £0.40 40109B £0.58 LM13700 £1.35 BFX29 £0.29 ZTX789A £0.41 quired, phone, 74LS133 £0.36 LMC660CN £1.26 7812 £0.23 BC184 £0.09 fax or email for 40174B £0.46 74LS136 £0.23 7815 £0.23 Potty about BC184L £0.13 BFX85 £0.33 ZTX790A £0.41 40175B £0.41 LMC6032IN £1.55 Pots! BFX88 £0.27 ZTX851 £0.50 a quote. 74LS138 £0.33 LP311N £0.74 78L05 £0.22 BC206B £0.72 74HC Series 74LS145 £0.56 78L06 £0.32 We now carry in BC208 £0.72 BFY50 £0.30 ZTX853 £0.50 LP324N £0.75 stock a wide 74HC00 £0.16 74LS148 £0.64 LP339N £0.75 78L08 £0.22 74HC02 £0.17 74LS151 £0.29 78L12 £0.16 range of LT1013CN8 £4.64 positive position We carry a large range of capacitors in stock, including: 74HC03 £0.21 74LS156 £0.36 M34-1 £0.30 78L15 £0.26 74HC04 £0.14 74LS157 £0.22 78L24 £0.39 pots. Ceramic Mini Disc, Dipped Ceramic Multilayer, Dipped & Boxed Polyester, M34-2 £0.30 With either with Mylar Film, Polystyrene, Plastic Film, MKT Polyester, Tantalum Bead, Sub-min- 74HC08 £0.17 74LS158 £0.21 MAX202CPE £2.00 78S05 £0.53 74HC10 £0.21 74LS160 £0.48 78S12 £0.42 a centre click or iature Radial, 105°C Radial, Low Leakage Radial, Non Polarised Radial & Ax- MAX208CN £6.99 41 click posi- ial, PCB Can Electrolytics, Polypropylene & Ceramic Trimmers and Tuning 74HC11 £0.21 74LS161 £0.32 MAX220CPE £5.06 78S15 £0.32 74HC14 £0.18 7905 £0.23 tions. Log, Lin, capacitors. Full technical details available. 74LS162 £0.44 MAX222CPE £5.06 per 100 of one 74HC20 £0.28 7912 £0.24 Single or Dual Resistors - Please State Value Required value only 74LS163 £0.32 MAX232CPE £1.30 gang. 74HC27 £0.16 74LS164 £0.43 7915 £0.22 1/8W Carbon Film 5% E12 Series 10-1M0 £0.02 Each, £0.80 per 100 MAX483CP £3.13 7924 £0.38 74HC30 £0.22 74LS165 £0.48 MAX485CP £2.04 ¼W Carbon Film 5% E12 Series 1 -10M £0.02 Each, £0.60 per 100 74HC32 £0.14 74LS173 £0.24 79L05 £0.20 ¼W Metal Film 1% E24 Series 10-1M £0.04 Each, £1.72 per 100 MAX631ACP £4.99 79L12 £0.26 ½W Carbon Film 5% E12 Series 1-10M £0.02 Each, £0.95 per 100 74HC42 £0.36 74LS175 £0.30 MAX635ACP £4.99 74HC73 £0.40 74LS190 £0.60 79L15 £0.28 2.5W Wirewound 5% E12 Series 01-220 £0.23 Each MAX1232CP £2.80 79L24 £0.30 1W, 2W, 5W, 20W, 25W & 50W also in stock - selected values only, contact sales dept. 74HC74 £0.15 74LS191 £0.27 MC1458N £0.27 74HC75 £0.31 74LS192 £0.60 ADM666AN £3.44 Preset Resistors - Please State Value Required MC1488 £0.40 L200CV £1.67 Mixed Packs Enclosed, 10mm Square Horz / Vert. 100 - 1M0 0.15W £0.12 Each 74HC85 £0.23 74LS193 £0.50 MC1489 £0.35 224 Ceramic 74HC86 £0.21 74LS195 £0.24 L296 £4.42 Skeleton, 10mm Dia. Horizontal. 100 - 1M0 0.1W £0.09 Each MC4558P £0.18 LM2940CT5 £0.84 Caps £8.50 Sub-min, 6mm Dia, Horizontal E3 200-1M0 0.1W £0.12 Each 74HC107 £0.40 74LS221 £0.41 MK484 £0.66 74HC123 £0.33 LM317LZ £0.25 120 Electrolytic Multiturn, 10mm Square, Top Adjust. E3 100 -1M0 0.5W £0.81 Each 74LS240 £0.32 NE521N £6.39 LM317T £0.30 Radil Caps £8.50 Multiturn, 19mm Long, End Adjust. E3 50-1M0 0.5W £0.59 Each 74HC125 £0.26 74LS241 £0.32 NE555N £0.16 120 Diode & Potentiometers - Please State Value Required 74HC126 £0.46 LM317K £2.28 74LS243 £0.30 NE556N £0.24 LM323K £2.40 Rectifiers £5.95 Single Gang ¼” Shaft, 25mm Dia. 470-2M2 Linear £0.56 Each 74HC132 £0.26 74LS244 £0.41 NE5532N £0.48 80 3 & 5mm Single Gang ¼” Shaft, 25mm Dia. 4k7,10k,47k,100k,1M,2M2 Log £0.56 Each 74HC133 £0.34 LM334Z £0.96 74LS245 £0.45 NE5534N £0.54 LM337T £0.64 Mixed LEDs £5.95 Dual Gang¼” Shaft, 20mm Dia. 1k0-2M2 Linear £1.54 Each 74HC137 £0.30 74LS247 £0.60 NE5539N £4.35 LM338K £5.31 610 E12 ¼W Dual Gang¼” Shaft, 20mm Dia. 10k-470k Logarithmic £1.54 Each 74HC138 £0.26 74LS251 £0.24 OP27CN £2.33 LM338T £1.10 Resistors £5.75 Switched ¼” Shaft, 20mm Dia. 1k0-2M2 Linear £1.92 Each 74HC139 £0.31 74LS257 £0.24 OP90GP £2.91 LM723 £0.40 480 E3 ¼W Switched ¼” Shaft, 20mm Dia. 4k7-2M2 Logarithmic £1.92 Each 74HC151 £0.33 74LS258 £0.24 Resistors £4.95 PCB Mount, Splined Shaft, 16mm Dia. 470-1M0 Linear £0.48 Each OP97FP £1.84 LP2950CZ5.0 £0.72 OP113GP £3.44 REF01CP £2.31 100 BC.. PCB Mount, Splined Shaft, 16mm Dia. 470 ,4k7,100k,1M0 Log £0.56 Each OP176GP £2.09 TL431CP £0.14 Transistors £9.90 Dual PCB, Splined Shaft, 16mm Dia. 10k,50k100k,500k Lin £1.05 Each OP177GP £1.76 Dual PCB, Splined Shaft, 16mm Dia. 10k,50k,100k,500k Log £1.00 Each
0709 Station Road Prices Exclude Vat @15%. Tel: 0191 2514363 UK Carriage £2.50 (less than 1kg) Cullercoats £5.50 greater than 1kg or >£30 Fax: 0191 2522296 Tyne & Wear Cheques / Postal orders payable to www.esr.co.uk [email protected] NE30 4PQ ESR Electronic Components Ltd. PLEASE ADD CARRIAGE & VAT TO ALL ORDERS Editorial Offices: EVERYDAY PRACTICAL ELECTRONICS EDITORIAL Wimborne Publishing Ltd., Sequoia House, 398a Ringwood Road, Ferndown, Dorset BH22 9AU Phone: (01202) 873872. Fax: (01202) 874562. Email: [email protected] Web Site: www.epemag.com See notes on Readers’ Technical Enquiries below – we regret technical enquiries cannot be answered over the telephone. Advertisement Offices: THE UK’S NO.1 MAGAZINE FOR ELECTRONICS TECHNOLOGY & COMPUTER PROJECTS Everyday Practical Electronics Advertisements Sequoia House, 398a Ringwood Road, Ferndown, Dorset BH22 9AU Phone: 01202 873872 Fax: 01202 874562 Email: [email protected]
Virging on the ridiculous VOL. 38 No. 8 AUGUST 2009 ! "# Editor: MATT PULZER $ Consulting Editors: DAVID BARRINGTON JOHN BECKER % & ' Subscriptions: MARILYN GOLDBERG & $ ( General Manager: FAY KEARN ' ' )* Editorial/Admin: (01202) 873872 Advertising and Business Manager: ] ' STEWART KEARN (01202) 873872 $ # & On-line Editor: ALAN WINSTANLEY ' ,) EPE Online (Internet version) Editors: CLIVE (Max) MAXFIELD and ALVIN BROWN \ Publisher: MIKE KENWARD . . & READERS’ TECHNICAL ENQUIRIES Email: [email protected] $ We are unable to offer any advice on the use, % purchase, repair or modification of commercial equipment or the incorporation or modification & ' of designs published in the magazine. We regret & ' that we cannot provide data or answer queries ' \ $ / on articles or projects that are more than five years’ old. Letters requiring a personal reply must ' ' $ % & be accompanied by a stamped self-addressed ' & % envelope or a self-addressed envelope and $ % & international reply coupons. We are not able to ' '' answer technical queries on the phone. $ ! ' % PROJECTS AND CIRCUITS % & % & ' All reasonable precautions are taken to ensure & ' & ' $ that the advice and data given to readers is reliable. We cannot, however, guarantee it and 0 ' & we cannot accept legal responsibility for it. \ 1 \ & ' A number of projects and circuits published in EPE employ voltages that can be lethal. You & $ should not build, test, modify or renovate any 2 item of mains-powered equipment unless you fully understand the safety aspects involved ' and you use an RCD adaptor. "# G $ 4 COMPONENT SUPPLIES We do not supply electronic components or kits $ for building the projects featured, these can be SUBSCRIPTIONS supplied by advertisers. AVAILABILITY Subscriptions for delivery direct to any address in the UK: We advise readers to check that all parts are Copies of EPE are available on subscription 6 months £19.95, 12 months £37.90, two years £70.50; still available before commencing any project in anywhere in the world (see opposite) and Overseas: 6 months £23.00 standard air service or £32.00 a back-dated issue. from all UK newsagents (distributed by express airmail, 12 months £44.00 standard air service or £62.00 express airmail, 24 months £83.00 standard air ADVERTISEMENTS SEYMOUR). EPE can also be purchased from service or £119.00 express airmail. retail magazine outlets around the world. 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Subscriptions start with the next available issue. We The Publishers regret that under no accept MasterCard, Maestro or Visa. (For past issues see circumstances will the magazine accept liability the Back Issues page.) for non-receipt of goods ordered, or for late SIMPLE DATA- LOGGING REMOTE BINDERS delivery, or for faults in manufacture. WEATHER STATION Binders to hold one volume (12 issues) are available from Cheap and easy to build the above address. These are finished in blue PVC, printed TRANSMITTERS/BUGS/TELEPHONE Runs for years on AA batteries with the magazine logo in gold on the spine. Price £7.95 Unattended remote operation EQUIPMENT Up to two years logging plus £3.50 p&p (for overseas readers the postage is £6.00 to everywhere except Australia and Papua New Guinea We advise readers that certain items of radio SOLAR WATER HEATING transmitting and telephone equipment which SYSTEM CONTROLLER Part 2 which cost £10.50). Normally sent within seven days, but Construction, testing and operation please allow 28 days for delivery – more for overseas. may be advertised in our pages cannot be legally used in the UK. Readers should check PICprobe Payment in £ sterling only please. Visa, Maestro and A PIC-based logic probe MasterCard accepted. Send, fax or phone your card the law before buying any transmitting or that fits inside a Biro number, card expiry date, valid from date and card security telephone equipment, as a fine, confiscation code (the last 3 digits on or just under the signature strip), of equipment and/or imprisonment can result PLUS BREADBOARDING PROJECTS JULY 2009 £3.95 with your name, address etc. Or order on our secure from illegal use or ownership. The laws vary AM Radio Sound Sensor server via our UK website. Overseas customers – your from country to country; readers should check credit card will be charged by the card provider in your local laws. local currency at the existing exchange rate.
Everyday Practical Electronics, August 2009 7 NEWS A roundupd off ththe llatestt t EEverydayd News from the world of electronics
Camming Piracy The UK government refuses to make laws which specifically ban camcording in cinemas. Barry Fox reports. I-DEF camcorders small enough cinemas. The 2008 installations have since then adapted to detect TV sets in homes Hto hide in a hat can now be used to been removed for fine-tuning, but modified without TV licences. With analogue TVs make pirate DVDs. The official line is that CamScans were recently re-installed at two the van can even tell what station the set Section 6 of the Fraud Act 2006 already UK cinemas. “We have sold eight systems is tuned to. covers camcording. But there have been no to MovieLabs in the US,” Simmonds said, “The system is still in development and successful test cases to prove it. Cinemas use referring to the Palo Alto, California-based it’s difficult to say what its final price will military-style night vision goggles to look for research and development think tank of the be,” says Simmonds. But the prototype pirates, but these are no help if the camcorder six major studios. “These have been used systems that TLS sold to MovieLabs is hidden. British company Technical Lamp by Disney and two security companies.” currently cost around £2000 for an eight- Supplies, of Slough, has now come up with When camcording is detected, CamScan screen control box, plus £200 per screen a way to detect a camcorder, even when it is triggers an alarm on a central console, for detection heads. “Unfortunately, I carefully hidden. alerting cinema security staff to where the cannot comment on those products at this CamScan electronically sniffs the cinema recording is taking place. Because the system time,” says MovieLabs President Steve for the tell-tale radio frequencies which leak can distinguish between different camera Weinstein. from a video camera. Each camera uses types, there need be no false alarms from As I have grown to expect, the Motion slightly different circuitry, so CamScan can cameras phones in pockets. CamScan also Picture Association retreats to a stunned distinguish one camcorder from another. waits for five minutes continuous recording silence when asked any remotely Says TLS, “CamScan offers cinema before the alarm is triggered. technical question. FACT, the UK’s anti- operators their first real chance to stop early For obvious reasons, TLS won’t divulge piracy organisation, is more forthcoming. pirated copies being illegally recorded.” technical details, but the basic idea “Yes there have been trials of CamScan The company placed 10 CamScan derives from detectors used during World which have shown some pretty good systems in UK cinemas last year, says War II and the Cold War to find spy radios results in detecting recording devices” TLS Sales Director Nick Simmonds. That by driving a van with sensitive electronics says Eddy Leviten, FACT’s Head of followed a 2006 pilot project in six UK down the street. The same system was Communications. MicroRFID Modules APDanglia have announced the release For a limited period only, APD www.apdanglia.org.uk – see their advert of the RFIDREAD series of three low- are offering EPE readers a 10% on page 79 of this issue. cost 125kHz RFID reader/writer modules, introductory discount on these products. including a PCB with RS232 and one To take advantage, go to www.apdan R/W PCB with UART Tx/Rx TTL output. glia.org.uk/offer.html. For free R/W Intended for OEMs and hobbyists alike, software download and more details of these small profile modules, complete with all their RFID products, go to built-in antenna, allow users to quickly and economically add an RFID reader/ writer to their own products without the need for lengthy research and development cycles. Each module comes com- plete with a simple-to-use set of commands for performing the standard functions required for accessing the popular EM4100 and T5557 transponders available on the market. Dimensions of the fully encapsulated microRFID module are only 25 × 25 × 10mm, including anten- na. Mounting to a PCB is via a 0.1-inch pinout header. These modules are said to be ideal for all embedded applications.
8 Everyday Practical Electronics, August 2009 PICO ADDS MATHS CHANNELS PicoScope, the PC oscilloscope software from Pico Technology, Another new feature is input filtering. You can now apply a digi- is one of the best-known oscilloscope packages on the market. Its tal low-pass filter with adjustable cut-off frequency to each input carefully designed ergonomics and clear, uncluttered display have channel independently. This can be used to reject noise and re- set a benchmark for PC oscilloscope displays. With the latest re- duce jitter, resulting in cleaner waveforms. lease, PicoScope can now display mathematical functions of input Among the other improvements in this release is the ability to use signals alongside the original inputs. the colour persistence and equivalent-time sampling modes at the To add a maths channel, just click a button and a wizard will same time. This allows you to spot intermittent glitches in fast re- guide you through the process. You can quickly select one of the petitive signals that are beyond the real-time sampling rate of the built-in functions, such as inversion or addition, or create your own oscilloscope. from the highly flexible equation editor. All the standard arithme- Alan Tong, managing director of Pico Technology, commented: tic, exponential and trigonometric functions are supported. You can “Since we launched PicoScope 6, we have been continually adding control the entire process using the mouse, or type equations using new features and improving its performance to make sure that our the keyboard if you prefer. customers always have the best available software. All these new The number of waveforms you can display is virtually unlim- features are available free of charge to new and existing users.” ited. You can have eight waveforms in one ‘view’, but if you need PicoScope 6.2.0 can be downloaded from the Pico Technology more you can simply open another view. Maths channels can be website at www.picotech.com. Free technical support and updates used in both oscilloscope and spectrum analyser modes. are available to all Pico customers. Free energy saving bulbs SchmartBoard Energy saving light bulb specialist Eco Promotion has launched a scheme in which consum- ers can take advantage of free energy saving light bulbs and benefit from substantially reduced patent energy costs. Eco Promotion, together with the Energy Saving Trust can assist UK householders SchmartBoard has announced that a switch from old style light bulbs to the next generation of money saving technology. patent has been granted for its ‘EZ’ tech- All traditional inefficient tungsten filament light bulbs are being phased out over the next few nology for hand soldering surface mount years, to be replaced by energy saving light bulbs. Savings made by switching to the new bulbs can technology (SMT) electronic components. be considerable – with an average of £3 per year for each bulb, that could represent a total saving In summary, the patent covers a modi- of around £45 per household. fication of circuit board technology. A There are currently two free offers available as part of the Eco Promotion. The first is for a free normal PCB consists of two main com- pack of ten 12W GE Energy Saving Trust-approved spiral bulbs worth £20. These high quality ponents on the surface. The solder mask, bulbs recently won the Which? Magazine ‘Best Buy’ and are considered to be one of the best which comprises the coloured areas, and energy saving light bulbs on the market. Savings made in the lifetime of this free pack of bulbs the electronic pads, which are the metal- is a staggering £180. Eco Promotion only requires you to pay for post and packing, full details lic areas. The electronic pads are on top of which can be found on their website. of the solder mask, and this is where the Also available as part of the Eco Promotion is a pack of two free GE Dusk to Dawn Sensor electronic components are placed. This Bulbs. These bulbs, worth £20, have been specially designed to improve your home security. At system works well when circuits are just 15W, the bulbs use considerably less energy than conventional bulbs and have the added fea- mass-produced using precise robotic pick ture of automatically switching on at dusk and switching off again at dawn, so giving the impres- and place technology. However, when cir- sion that someone is at home, even when the house may be empty. Again these bulbs are currently cuits need to be hand soldered for projects available free of charge from Eco Promotion with just the post and packing to pay for. or prototyping, the average engineer does Eco Promotion claims it is now one of the UK’s leading suppliers of energy saving products and of- not have the dexterity or expertise to do it. fers Heatkeeper radiator panels, safety packs, solar kits and energy saving kits. Working closely with SchmartBoard’s new patent calls for the the Energy Saving Trust, the company is constantly searching for new and innovative energy saving solder mask to be much higher than the and eco-friendly products to add to its range. Dealing exclusively with top of the range manufacturers pads. Additionally the pads are pre-tinned such as GE Lighting, JML, Proteam and Solar Technology Ltd, the company says it has built up an with solder. What this modification does enviable reputation as one of the UK’s leading online suppliers of energy saving products. is allow the electronic components to eas- Visit www.ecopromotion.co.uk to claim the free energy saving light bulbs. ily be hand placed by virtually anyone. Because the solder is already on the pads, a user simply takes a soldering iron and melts the solder to the component leads Three new gas GPS Receiver Module or runs the boards through a re-flow oven. Parallax has just released a new product, This technology makes it virtually im- sensors from Parallax the PMB-248 GPS receiver module. With this possible to create shorts or bridges when Parallax has released three new gas sen- module you can track up to 12 satellites to hand soldering SMT components. sors each designed for use in gas detection pinpoint your location on the globe. With TTL “Our technology is utilised by three equipment: and RS-232 level outputs you can connect this main user groups: industry, education and The MQ-7 CO gas sensor can be used receiver to any microcontroller or your PC. hobbyists,” says Neal Greenberg, Schmart- to detect the presence of carbon monoxide Small size and low power consumption make Board’s VP sales and marketing. “It has in home, automotive or industrial settings. this GPS receiver a great choice for robotics, saved significant time and money for in- It has high sensitivity to carbon monoxide vehicle tracking, fleet management and auto dustry, allowed SMT technology to be used (CO) gas, a stable and long life and a sim- pilot, as well as for navigation systems. in education, and has made it possible for ple drive circuit. This high sensitivity GPS receiver features hobbyists to use current component tech- the SONY CXD2951A-4 chipset and includes nology. SchmartBoard’s website has vid- The MQ-2 methane gas sensor can be a built-in rechargeable battery for memory eos of SMT parts being soldered and offers used to detect the presence of methane in and RTC backup. The receiver can track up to a free demo board with chip for users to try home, automotive or industrial settings. It 12 satellites for fast acquisition and supports for themselves before purchasing.” has a wide detecting scope, a stable and the NMEA0183 V2.2 protocol. For more information browse www. long life, a simple drive circuit and a fast For more information visit www.parallax.com. schmartboard.com. response with high sensitivity. The MQ-5 LPG gas sensor can be used to detect the presence of propane in home, automotive or industrial settings. It has a high sensitivity to propane gas, a stable and long life and a simple drive circuit. If you have some breaking news you would like to share with our readers then please email: For more information visit www. parallax.com. [email protected]
Everyday Practical Electronics, August 2009 9 Constructional Project Rolling Code Keyless Entry System
Versatile IR unit also functions as an alarm
Part.1: By JOHN CLARKE
Ideald l forf keylessk l entryt forf doorsd ini cars, hhomes bbe copied,d whileh l many conventional RF and infrared transmitters are far from and industry, this Keyless Entry System features tamper-proof. One technique is to use a rolling code to ensure high security. It also a special receiver to intercept and copy the transmitted code. Once copied, the has two door-strike outputs, an alarm system " # and provision to use up to 16 separate keyfob In fact, this technique was com- transmitters with the same receiver. monly used by car thieves in carparks OTS OF DIFFERENT electronic sys- with the door lock mechanism. The Ltems have now been developed for " keyless entry. These include systems is unique to each individual lock and " that require a coded electronic key, this data must match the data stored such as RF and infrared transmitters, in the receiver before the lock will be Rolling code security ! - Modern transmitters now circum- Devices), keypads and swipe cards. lar to a standard metal key, which has " " There are also units that do not require a $ coded electronic key and these include ! if an unauthorised person captures match the tumblers within the lock in # order for the lock to open. code will not unlock the door. This is usually comprise a small keyfob-style With any type of lock, there is always because the door lock is now expect- a problem of security. Keys can easily % "
10 Everyday Practical Electronics, August 2009 Constructional Project
that both the transmitter and receiver have in common. Features This code changing technique is commonly called a ‘rolling code’, Transmitter although it is sometimes also called s Rolling code infrared transmission ‘code hopping’. It renders copying s Small keyfob style case useless and thus provides a very high Dual function buttons level of security. It is also virtually im- s Randomisation of code parameters feature possible to send a correct code without s having a valid rolling code transmitter. s Synchronising of parameters feature This is because of the huge number of s Up to 16 identifications code variations possible. Receiver Because of its security advantages, a 12V operation rolling code transmitter forms the basis s Up to 16 separate transmitters can be synchronised of the Rolling Code Keyless Entry Sys- s tem described here. In fact, the odds of s Dual function with an independent output picking a correct code at random for s Two alarm inputs with exit and entry delays our rolling code transmitter are one s Two door strike outputs in 1.4 trillion or roughly one in 1012. s Alarm output If you want to know more about s Arm/disarm output and LED indicator rolling code transmissions, refer to the IR receive acknowledge LED separate panel elsewhere in this article. s s Strike 1 operates on arm, disarm or both Main features s Strike 2 operates independently with momentary operation or toggle output Our new Rolling Code Keyless Entry Arm output invert option System comprises a small keyfob-style s transmitter and a separate receiver. s Adjustable door strike, entry/exit delay and alarm periods The transmitter is small enough to s 200-code look ahead feature be attached to a keyring, and has two s Transmitter lockout feature pushbutton switches, each capable of sending a separate code. Each time delayed inputs allow the alarm to be First, each transmitter must be given a one of the switches is pressed, a small armed while giving the user enough separate identity ranging from 1 to 16. &' time to exit the door without setting off This is selected using link options on the transmitter has sent its code. the alarm. An identical delay period al- the transmitter board, but note that no The larger of the two switches lows the alarm to be disarmed on entry. two transmitters should be given the activates the alarm functions of the During the exit delay period, the ARM same identity. receiver. It arms the unit so that it &' Second, the transmitter must be will sound an alarm should there be on and off at a one second rate. At the randomised. This changes the initial unauthorised access. end of the exit delay, this LED indicates rolling code and algorithm parameters The alarm functions include an elec- " " to ensure that the transmitter code is tric door strike control (this allows the once every second. This conserves going to be unique. door to be opened), two alarm inputs power and increases its effectiveness The third step involves synchronising (eg, to monitor doors, windows or other when it comes to attracting attention. the transmitter and receiver. This proc- sensors), and an arm/disarm output. An Acknowledge/Power LED is also ess involves sending the rolling code The door strike can optionally be set to included in the receiver. This normally parameters to the receiver, as described operate on arming, on disarming or both. % next month. You can synchronise from In addition, an alarm output is However, when the receiver picks up 1 to 16 transmitters, provided each has provided to sound a siren if required. a signal from the transmitter, the Ack/ a different identity. The second, smaller pushbutton + % &' Also included is a facility to prevent switch on the transmitter is independ- also shows if the received code is invalid any or all transmitters from operating ent of the alarm. It can be used to by momentarily blinking off and on. the receiver once they have been syn- operate a separate door strike or some If the code is correct, the receiver chronised. This ‘lockout’ feature can be other device connected to the receiver. responds to the signal. The transmis- useful if a transmitter has been lost and Such devices can include a light or a sion range is about 4m, which should you no longer want it to work with your siren that can be used as a panic alarm. " Note, alarm system. This can be optionally set to operate however, that it will not work if the A transmitter identity can be momentarily or can be toggled on and IR receiver is in direct sunlight. locked out individually, but if you off with each switch pressing. don’t know the identity of a lost The door strike outputs can be set to Setting it up transmitter, all identities can be operate from between 0 to 64 seconds, Before using the Infrared Rolling locked out. The transmitters that are while the inputs can include delayed Code Alarm, both the transmitter and to be used with the receiver are then operation from 0 to 64 seconds. These the receiver must be set up correctly. re-synchronised.
Everyday Practical Electronics, August 2009 11 Constructional Project
would be around 4mA because of the Parts List – Rolling Code Keyless Entry System quiescent current of the 5V regulator. Conversely, pressing either S1 or Receiver Transmitter S2 connects the 12V battery to the input of regulator REG1 via diode 1 PC board, code 721, size 1 PC board, code 722, Ω 61mm × 122mm measuring 30 × 36mm D1 or D2. A 22 resistor is included 1 UB3-type plastic box, size 1 keyfob remote control in series between the battery and the switches to limit the initial charging 130mm × 68mm × 44mm case (Jaycar HB-5605 or μ 5 2-way PC-mount screw equivalent) current into the 1 F bypass capacitor terminal blocks (5mm or 1 12V A23 car alarm battery (9.5 at REG1’s input. This minimises wear 5.08mm pin spacing) diameter × 27mm) on the switch contacts. 1 SPST vertical mount micro 2 SPST SMD tactile switches 6 × When power is applied to REG1’s tactile switch, with 0.7mm 6 × 3.85mm (S1,S2) input, its output delivers a regulated actuator (S1) 1 TO-3P transistor silicone +5V rail to IC1. As a result, the micro 3 3-way pin header terminal insulating washer, cut to 20 × powers up and runs its internal soft- strips (2.54mm spacing) 24mm ware program. 4 2.54mm jumper shunts 5 PC stakes Switch check 3 PC stakes 1 25mm length of 0.8mm tinned 1 25mm length of 0.8mm tinned copper wire 7 copper wire 1 ICSP 5-pin connector (CON1) does is check which switch was pressed (this happens after a short Semiconductors Semiconductors delay to make sure the switch is fully 1 PIC16F88-I/P microcontroller 1 PIC16F628A-20/SO closed). In operation, the program can programmed with irrcroll.hex 18-lead SOIC microcontroller, decide if S1 or S2 is pressed because of Ω (IC1) programmed with irxmroll.hex the 10k resistor connected between 1 78L05 low-power 5V regulator (IC1) S2 and the micro’s RA4 input. (REG1) 1 MC78M05 DPAK 5V regulator It works like this. Initially, RA4 is 1 38kHz infrared receiver (IRD1) (REG1) set low by the program. This pin is 2 BD681 Darlington NPN 1 MMBT100 SOT-23 SMD NPN then made open circuit so that it can transistors (Q1,Q2) transistor (Q1) be pulled high if switch S2 was closed. 2 BC337 NPN transistors (Q3,Q4) 1 MMBT200 SOT-23 SMD PNP However, if S1 was closed instead, the 1 16V 1W Zener diode (ZD1) transistor (Q2) RA4 pin will stay at 0V. By checking 4 1N4004 1A diodes (D1-D4) 2 1N4148 diodes (D1,D2) the voltage on RA4, the program can 1 1N5404 3A diode (D5) 1 3mm infrared emitting LED thus determine which switch was 2 3mm red LEDs (LED1,LED2) (LED1) pressed and initiate the correct func- 1 green gull wing style surface tion codes for that switch. Ω Capacitors mount LED (2.2 × 2.2mm) The 10k resistor is necessary to 5 100μF 16V PC electrolytic (LED2) limit the current into the internal 3 100nF MKT polyester clamping diodes at RA4 when S2 is 3 10nF MKT polyester Capacitors closed. In practice, the positive clamp 1 1nF MKT polyester 2 1μF monolithic ceramic diode will conduct, clamping the RA4 1 100nF monolithic ceramic input to 0.6V above the +5V supply. Resistors (0.25W, 1%) This protects the input from damage. 4 10kΩ 1 220Ω Resistors (0.25W, 1%) Diodes D1 and D2 protect the regu- 2 2.2kΩ 2 100Ω 2 10kΩ 2 22Ω lator from reverse polarity should the 2 1kΩ 1 10Ω 3 1kΩ battery be inserted the wrong way Ω around. These diodes also isolate the 2 680 2 10kΩ horizontal trimpots switch outputs from each other, so that (VR1,VR2) Test Components the RA4 input will only go high if S2 4 red LEDs Printed circuit boards available is pressed. If S1 is pressed, the 12V at 4 2.2kΩ 0.25W 1% resistors from the EPE PCB Service REG1’s input reverse biases D2, and so is blocked from reaching RA4. Next, the program sets RA2 at pin 1 Transmitter circuit hidden inside the PIC micro, including of the micro high. This output drives OK, so much for the background the software necessary to generate the the base (B) of NPN transistor Q1 details. Let’s now take a look at how rolling code. via a 10kΩ resistor. As a result, Q1 the circuit works, starting with the Under normal conditions, switches switches on and this in turn switches transmitter – see Fig.1. S1 and S2 are open circuit and transis- on transistor Q2. IC1, a PIC16F628A microcontroller, tor Q2 is off, so no power is applied. This action latches the supply to forms the heart of the transmitter This is done to ensure long battery life. regulator REG1, even if switch S1 or S2 circuit. The circuit might look quite If power were continuously applied, is released. This is necessary to allow simple, but there are a lot of ‘smarts’ the current drawn from the battery time for the rolling code calculations to
12 Everyday Practical Electronics, August 2009 Constructional Project
+5V
INFRARED ROLLING CODE TRANSMITTER
Fig.1: a PIC16F628A microcontroller forms the heart of the transmitter circuit. It contains all the software necessary to generate the rolling code and drives an infrared LED (LED1). be made and stored without interrup- RA0, RA7 and RA6. As shown, each This oscillator has a 1% tolerance tion, otherwise the code may become individual input can be connected to corrupted. It also ensures that the roll- either the +5V supply or the ground (0V) application (ie, there’s no need for a ing code is transmitted in its entirety. supply, but NOT to both or the supply crystal oscillator). However, because The next stage in the program in- will be shorted. The number of possible the oscillator frequency can vary volves calculating the code and storing combinations is 16. with temperature, we have included the values. This calculation is based Each of these inputs is initially tied a means for the receiver to lock onto on the previously transmitted code to +5V on the PC board (via thin PC the transmitter’s clock rate, so that and uses an internal algorithm. Once tracks) and this selection is identity 1. variations over a long time period do calculated, the new code appears at The other 15 identities are selected by not matter. outputs RB0 to RB5, which in turn breaking one or more of these connec- By the way, the transmitter uses drive an infrared LED (LED1). The 22Ω tions to the +5V rail and connecting several surface-mount components resistor in series with LED1 limits the them instead to an adjacent 0V rail. % current to a safe value. We’ll talk more about this in the keyfob case. These surface-mount In operation, LED1 is driven using construction. parts include IC1, REG1, Q1, Q2, 100mA pulses at a rate of 38.46kHz. A LED2, S1 and S2. The remaining parts high (or a ‘1’) is transmitted as a 512μs In-circuit programming are standard through-hole component burst of 38.46kHz signal, followed by Five-pin header CON1 is provided 512μs of no transmission. Conversely, a on the circuit to allow for In-Circuit the PC board. low (or a ‘0’) consists of a 512μs period Serial Programming (ICSP) of IC1 us- of no transmission followed by a 512μs ing a PIC programmer. Alternatively, Receiver circuit burst of 38.46kHz signal. we have developed a surface-mount Refer now to Fig.2, which shows LED2 is the Transmit LED and is converter board that will allow IC1 to the receiver circuit. It’s built around driven by output RA3 during code be programmed directly using a PIC infrared receiver IRD1 and PIC mi- transmission. Basically, RA3 goes high programmer. We’ll publish the details crocontroller IC1, the latter operating each time there is a ‘1’ in the transmit- on this next month. at 4MHz to match the transmitter’s ted code, and low each time there is a The ICSP connections on the frequency. Once again, much of the ; = &' > transmitter are also used to run the complexity is hidden by the software the transmission code. randomisation and synchronisation programmed into the microcontroller. functions using a bridge between pins IRD1 only has three leads, but inside Transmitter identity 3 and 5 and 3 and 4 respectively. it comprises a complete infrared de- Transmitter identity is selected using IC1 runs at a nominal 4MHz, as tector and processor. First, it receives the LK1 to LK4 link connections to RA1, provided by an internal oscillator. the 38kHz infrared pulse signal from
Everyday Practical Electronics, August 2009 13 Constructional Project
% " % " Specifications % % ^ % % % " Transmitter Standby current: 0mA Total transmit current: rolling code transmission = 35mA for 80ms; synchronise = 35mA for 100ms; randomisation = 10mA. % % Infrared transmit frequency: 38.46kHz % Code transmission rate: 1.024ms Encoding: a high (or a 1 bit) is transmitted as a 512μs burst of 38.46kHz Door strike outputs infrared signal, followed by 512μs of no transmission. A low (or 0 bit) is transmitted by a 512μs period of no transmission, followed by a 512μs ] burst of 38.46kHz infrared signal. " `] ! Rolling code: sends four start bits, an 8-bit identifier, the 48-bit code plus ] > four stop bits. The start bits include a 16.4ms gap between the second start bit and the third start bit. $ ] $ > Synchronise code: sent as two blocks. Block 1 sends four start bits, the = % ] > Ω 8-bit identifier, a 32-bit seed code and four stop bits. Block 2 sends four ~X; `] ^; start bits, a 24-bit multiplier, the 8-bit increment and 8-bit scramble values, => ] and four stop bits. The start bits include a 16.4ms gap between the second > start bit and the third start bit. " % Code randomisation: alters the multiplier values, the increment value, the μ % scramble value and the seed code at a 40 s rate. ! ] > " Infrared transmission range: 4m ^ ~X] " ] \= = Receiver % Supply Current: 7.6mA typical when armed and with no external devices " X;; = ]>| powered. ! % = = - Strike 1 period: adjustable from 0-64 seconds in 0.25s steps " _ J " approximately. ^`JJ _ " Strike 2 period: adjustable from 0-64 seconds in 0.25s steps `] ^] >>;Ω approximately. Z % " Input 1 delay: adjustable from 0-64 seconds in 0.25s steps approximately for exit and entry delays. >;; = Input 2 delay: adjustable from 0-64 seconds in 0.25s steps approximately [ for exit and entry delays. $ J Alarm period: adjustable from 0-128 seconds in 0.50s steps ]; Ω `] ^> approximately J = " ! ! ] ! % ] Ω JX Z[ " > ^\ # " % = \;Z[ ];;Z[ ^~ `] > > Ω {]>| ' " % " % ;| ]>| " ] ];; = J " ] ! ] ]; Ω " % " ^_ `] ];;Ω " ] Ω = ] ^\ ^~ % {\| # a 285Ω ]>| ] % ! " - {\| = ];;Ω # 7 # % J % ];;μ - % - ! &_ " &_ { J 7 % % % % " % ^J = % % % ` - {\| % + ` ` % # % `]
14 Everyday Practical Electronics, August 2009 Constructional Project
SYNCHRONISE
INFRARED ROLLING CODE RECEIVER
Fig.2: infrared receiver IRD1 and PIC microcontroller IC1 are the main parts in the receiver. IRD1 picks up and demodulates the infrared transmissions, while IC1 decodes the data and drives the various outputs.
Moving LK4 to the ‘–’ position pulls &] " To test if the link is in the ‘+’ position RB3 to ground and changes the sense {\| ;| or open, the RA7 pin is made an output of the Arm output. In this case, Q3 " ! % ;| ! is off when the unit is armed and on determine how the Strike1 output RA7 pin is then changed to an input when disarmed. ^ $ ] " and the level checked again. If the volt- LED 2 indicates the state of the unit. to operate when the unit is armed, % " It’s driven from the RA4 output of IC1 % " - { ` via a 1kΩ % ing and disarming. voltage is low, then the link is open. the unit is armed. In operation, the software pro- ! ]; Ω resistor in series with RA7 ! % grammed into the PIC micro decides is there to prevent shorting when this - % " pin is taken high and low with a link &' % \; few tests. First, it takes the RA7 output in position. \| = LK2 sets Strike2’s operation for off for half the time). However, at the an input to read the voltage. If the volt- % % " toggle operation. This link pulls the _ the ‘–’ position. However, if the input =\ {\| % " remains high, then the link is either { ;| in the ‘+’ position or is open circuit % Other link options % " Links LK1, LK2 and LK3 are in- " " =\ " cluded to provide further options. ]; as an input.
Everyday Practical Electronics, August 2009 15 Constructional Project
Note: transistor Q2 mounts under 10kΩ resistor
These two larger-than-life-size photos clearly show how the parts are mounted on the transmitter board. You will need a
/ 04 5% 5 * 5 % 79 790 transmitter board. The transmitter 5 % Fig.3: follow these parts layout diagrams to build the transmitter board. Note % 5 5 ! ;<= * Ω " $% & ' * + ' 5 $=
LK3 is used in conjunction with to each analogue input is converted to addition, if S1 is closed during power- trimpots VR1 and VR2 to set the various a digital value within the software and up, it selects the transmitter identity time periods. These include the Strike1 it is these values that determine the lockout function. and Strike2 momentary on periods, the timeout periods. entry and exit delays for Input1 and Power supply Input2, and the alarm period. Synchronise switch Power for the circuit is from a As shown in Fig.2, trimpots VR1 and Switch S1 is the Synchronise switch, 12V supply such as a battery or DC VR2 are connected across the 5V sup- and this connects to the RB7 input. plugpack. Diode D5 provides reverse ply and their wipers (moving contact) This input is normally held high via polarity protection and is rated at 3A connect to analogue inputs AN0 and an internal pull-up resistor, but when so that it can handle the currents that AN1 respectively. The voltage applied S1 is closed, it pulls RB7 to 0V. may be drawn by an electric door strike Basically, and siren. S1 is used to The 10Ω resistor and Zener diode Capacitor Codes synchronise ZD1 provide transient protection, with the receiver the Zener clamping voltages over 16V. Value μF Code IEC Code EIA Code with the The 10Ω resistor limits the current 100nF 0.1μF 100n 104 transmitter. through ZD1 to a safe level. % ] 10nF .01μF 10n 103 It is also used when set- using a 100μF capacitor and applied 1nF .001μF 1n0 102 ting the time to the 3-terminal regulator REG1. The periods. In resulting regulated +5V rail is then
Resistor Colour Codes (Transmitter)
❏ No. Value 4-Band Code (1%) 5-Band Code (1%) ❏ 2 10kΩ brown black orange brown brown black black red brown ❏ 3 1kΩ brown black red brown brown black black brown brown ❏ 2 22Ω red red black brown red red black gold brown
16 Everyday Practical Electronics, August 2009 Constructional Project
Table 1: Transmitter Identity Iden- LK1 LK2 LK3 LK4 tity 1 ++++ 2 +++- 3 ++-+ 4 ++- - 5 +-++ 6 +-+- 7 +--+ The keyfob case is supplied with Fig.5: once the switch covers have 8 +--- the key switch covers mounted as & shown here. This assembly must be down using 180-grit sandpaper, so 9 -+++ removed. that only the tops remain (see text). 10 -++- 11 -+-+ 12 -+- breaks in the copper or shorts between transmitter’s identity – but only if more 13 --++tracks. Repair any faults that you do than one transmitter is to be used. If 14 --+- more than one transmitter is used, then 15 ---+shape of the board. It should have a each will require a unique identity. = +` " - 16 ----curved front edge and a small circular tially ties links LK1 to LK4 to the there should be two slots for the bat- {\| ! ] % `] tery clips. or ID1. If only one transmitter is to ] +` " " + % neatly into the base of the keyfob case. " &' ] % % ] &' ] it neatly along the edges until it does. If you do wish to change the iden- % _ " % Z % % Setting the identity more of the links as shown in Table Before mounting any of the ] " " at the infrared reception rate. & 5 thinned connection to the +5V track &' ] % cycle for a short time at the end of synchronisation and if the infrared signal is incorrect. Construction ! ` ' $ " % +` " " >] ! " code 722. Both boards are avail- able from the EPE PCB Service. % " % Above: the finished transmitter % " board inside its keyfob-style plastic " J; case. Power comes from a 12V A23 car alarm battery. Note how the K J~ # keyswitch covers are mounted on components. the lid, using a 20 × 24mm silicone Z % washer – see text. Reproduced by arrangement > % $ & `7 `Z + = [ >;; " www.siliconchip.com.au while a length of 1.5mm de-soldering Right: the two keyswitch " $ % % " - covers are attached to the 20 × 24mm silicone washer ful for cleaning up any excess solder as shown here. Use silicone % " % sealant to ‘glue’ them in J % place. The keyfob lid can be +` " ! used as a template to position +` " them correctly.
Everyday Practical Electronics, August 2009 17 Constructional Project
Fig.6: follow this diagram to mount the parts on the receiver board. Use a socket for the PIC microcontroller and take care to ensure that all polarised parts are correctly orientated. The infrared receiver module (IRD1) can either be mounted on the board (as in the prototype) or connected via shielded cable (see diagram next month).
and connecting it to the adjacent 0V to program the PIC yourself using a up with the tracks and use a clothes track instead via a small solder bridge. suitable programmer. As previously peg (or some other small spring-clamp) Make sure, however, that a link con- mentioned, we have provided two pro- to hold it in position. nection is not made to both the +5V and % That done, solder a couple of di- 0V tracks. We have labelled the +5V is to use the in-circuit programming agonally opposite pins, check that connection with a plus (+) sign and the connector on the PC board. everything is correct, then remove the 0V connection with a minus (–) sign. Alternatively, you can build and use peg and carefully solder the remain- It is important to select the identity the surface mount adaptor board to be ing pins. now because the +5V track section described next month, so that IC1 can The main thing to watch out for here cannot be accessed when IC1 is in be programmed out of circuit. is unwanted solder bridges between place. The +5V connections should ! % % " " adjacent copper tracks. If this does only be broken with a sharp craft via the EPE Library site, accessed via happen, use some solder wick to draw knife and, once broken, should not be www.epemag.com. Pre-programmed up the excess solder to clear the short. resoldered. That’s because IC1 would PICs will also be available from Ma- A magnifying glass will be handy here no longer sit properly on the board, genta Electronics – see their advert in to inspect your work. the issue for contact details. Note that pins 6 to 9 and 10 and The selected identity should be 11 are connected together anyway, so marked on the back of the PC board Parts assembly solder between these pins is OK. using a marker pen. For example, if Except for a single wire link, all Once the IC is in, you can install the the identity is 2, write ID2 on the PC parts for the transmitter mount on link beneath it on the other side of the board. This number can also be written the copper side of the PC board. Don’t " ! on the back of the keyfob transmitter install the link yet though – that step the board, otherwise the board will not case, in the indentation provided. comes after you install IC1. sit down in the case correctly. To install IC1, position it on the The remaining surface mount Software board with its pin 1 at top right – see components – Q1, Q2, LED2 and If you are building the unit from Fig.3 (pin 1 is indicated by a small REG1 – can now be soldered in place. a kit, then IC1 will be supplied pre- adjacent dot in the body of the IC). Transistor Q1 has an N1 label on its programmed. If not, you will have Carefully adjust it so that its pins line top, while Q2 has an N2 label instead.
Resistor Colour Codes (Receiver)
❏ No. Value 4-Band Code (1%) 5-Band Code (1%) ❏ 4 10kΩ brown black orange brown brown black black red brown ❏ 2 2.2kΩ red red red brown red red black brown brown ❏ 2 1kΩ brown black red brown brown black black brown brown ❏ 2 680Ω blue grey brown brown blue grey black black brown ❏ 1 220Ω red red brown brown red red black black brown ❏ 2 100Ω brown black brown brown brown black black black brown ❏ 1 10Ω brown black black brown brown black black gold brown
18 Everyday Practical Electronics, August 2009 233 2009-07-13 16:04:30 Constructional Project
The assembled PC board clips neatly into a standard plastic utility case. The full installation and setting up details for the receiver will be in Part 2 next month.
These numbers relate to the MMBT100 LED1 can go in next. Its anode lead a matter of attaching the switch covers and MMBT200 types respectively. % &' > to this washer using silicone sealant – Don’t get them mixed up. and this lead must go towards IC1. To " - " % " plate to position the covers correctly. Installing the semiconductors ;$ > " The orientation of the two transistors insert the leads into the PC board. Fi- Receiver assembly is obvious – they have one pin on one nally, push the LED all the way down Now for the receiver – see Fig.6. side of the body and two on the other onto the PC board, solder the leads = " +` side. REG1 has a GND tab plus IN and % " ` OUT pins that must be soldered to the Note that a small circular notch is the hole sizes for the screw terminal PC board. The central pin between the " " " IN and OUT pins is left unconnected. for the LED to sit in. This can be made necessary. Be careful with the orientation of # ! +` " LED2 – its cathode lead is the longer " of the two. " " Next, solder in switches S1 and S2, " +` `$+ Battery terminals % " % - header. These pins are inserted from The battery terminals are installed rectly into the wall slots. the non-copper side of the PC board " +` " " Fig.6 shows the assembly details. and soldered in position. The pins of the case. That done, the terminals % are then trimmed on the copper side are slid into position and soldered. the resistors. The accompanying table to 3mm in height. On the underside, % shows the resistor colour codes, but ; \ spring is located as shown in Fig.3. The standard components can now digital multimeter. be installed. These must be mounted +* 5 5 5 ! ` +` " ! % - % " ]; Ω % " " the correct polarity. Follow these with > ! % % with the orientation of diodes D1 and the PC board. the electrolytics go in correctly. The D2 and note that the tops of the three As supplied, the two switch covers +` !+] !+> !+ monolithic capacitors must be no more - can then be installed. than 4mm above the PC board. fob lid. This assembly must be removed Depending on your requirements, In particular, the two capacitors near and the covers carefully ground down LEDs 1 and 2 can either be mounted '] " " _\$ % ] \ \ ! directly on the PC board or mounted the one adjacent to IC1 needs to have its by placing some 180-grit sandpaper externally and connected using wire leads adjusted so it can be pushed down " % leads. Be sure to mount each LED onto the PC board far enough to meet the " with its cathode lead (the shorter of 4mm height requirement. That done, cut out a 20 × 24mm the two) towards the lower edge of Cut all the leads beneath the PC rectangular piece from a silicone TO-3 the PC board. " # % >; K >_ % Similarly, IRD1 can either be mounted with the surface. switch cover assembly. It’s then simply directly on the PC board or connected
Everyday Practical Electronics, August 2009 19 Constructional Project
Frequently Asked Questions One question that’s often asked been made, the receiver changes its because of the look ahead feature to a 1 about rolling code systems is what synchronisation method. in 1.4 × 1012 chance of striking the cor- happens if the transmitter is out Basically, the receiver requires two rect code – still impossibly long odds. of range and one of the transmit separate transmission codes before switches is pressed? Will the receiver restoring correct operation. On the Code scrambling still work when the transmitter is later first transmission, it calculates the A further complication with the brought within range and the button next code it should receive using this transmitted code is that the code is not pressed again? received code as the basis for calcu- necessarily sent in sequence. There This question is asked because the lation. If the second code sent by the are also 32 possible scrambling vari- code the receiver was expecting has transmitter is the same as the code that ations that can be applied to the code. already been sent and the transmit- was calculated, the receiver operates. What if the transmitter sends two ter has rolled over to a new code. So The drawback of this latter scheme consecutive codes that are the same how does the system get around this is somewhat less security since, in and the code is intercepted and re- problem? theory, two successive transmission transmitted to open the lock? This is The answer to this is that the receiver codes could be intercepted and re- highly improbable and our rolling code will acknowledge a signal that is the corded. These codes could then be transmitter has safeguards to prevent correct length and data rate, but it will re-transmitted to synchronise and the same code appearing twice in suc- not trigger unless it receives the correct thus trigger the receiver. cession. For each code calculation, code. So if the signal format is correct a comparison is made between the but the code is incorrect, the receiver Calculating the code current and last code. If the code is the then calculates the next code that it Another question that’s often same, the code is recalculated after an would expect, and checks this against asked is how does the receiver know increment of the code value to ensure the received code. If the code is now which code to expect from the trans- successive code calculations diverge. correct the receiver will unlock the door. mitter, since this changes each time? It is this new code that is transmitted. If the code is still incorrect, the The answer to this is that the trans- The receiver performs the same receiver calculates the next expected mitter and the receiver both use the recalculation so that the new code code and will do this up to 200 times. same calculation to determine the will be accepted. If none of these are correct, the re- next code. They also both use the Another question concerns the use ceiver keeps its original code, but it same variables in the calculation and of different transmitters. Does each will not trigger. In fact, the only way these variables tend to be unique transmitter use the same rolling code to trigger the receiver after this is to values that no other transmitter uses. calculation and if so, wouldn’t the re-synchronise it to the transmitter. For example, if the calculation for receiver lose its synchronisation if Of course, a second transmitter will consecutive codes requires the origi- several transmitters were used? The still operate the receiver (provided nal calculated code to be multiplied answer is that the receiver will not they have been synchronised in the by 100 and the number 7 added to it, lose synchronisation, even if one of first place). That’s because this trans- then both the transmitter and receiver the transmitters is not generally used. mitter has a different identity and a will use these numbers to perform This is because each transmitter op- different code to the other transmitter. the calculation. erates independently from the others. Without knowing both the mul- Only 16 transmitters can be used Automatic synchronisation tiplier and the increment value, it with a given receiver and each must Some rolling code transmitters sys- would be very difficult to predict the have its own different identity from tems offer automatic synchronisation next code. This is particularly true 1 to 16. The identity is built into each if the transmitter and receiver lose because of the very large numbers transmitter and synchronisation is sync. In these systems, the receiver involved. The values quoted for the required for each transmitter. includes a code ‘look-ahead’ feature, multiplier and increment value are not The codes sent by each transmitter as described above, but the number as simple as 100 and 7 but are 24 bits are different and the code includes the of look-ahead codes is usually limited and eight bits respectively in length. transmitter identity value. The receiver to fewer than 200. What happens is In addition, the code length is 48 bits has 16 different rolling code and that if the code is not recognised after with as many as 2.8 x 1014 combina- calculation parameters, and so each all the look-ahead calculations have tions. This reduces by a factor of 200 transmitter is treated independently. using twin-core shielded cable (see Finally, complete the board assem- That’s all we have space for this diagram in Part 2 next month). bly by installing switch S1 and the month. Next month, we’ll complete the Trimpots VR1 and VR2 and the screw terminal blocks. Note that the construction and describe the installa- 3-way and 2-way pin headers for LK1- 6-way terminals at the righthand edge tion and setting-up procedures, includ- LK4 are next on the list. That done, of the PC board are made up using ing setting the entry and exit delays. install REG1 and transistors Q1 to-Q4. three 2-way blocks. These are joined We’ll also describe the optional SOIC Q1 and Q2 must be installed with their by sliding their dovetail joints together adapator board, so that you can program metal faces towards IC1. before installing them on the PC board. the PIC microcontroller out of circuit.
20 Everyday Practical Electronics, August 2009 SHERWOOD ELECTRONICS
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www.picotech.com/scope1024 01480 396395 Diatomic Power Mark Nelson
Renewable energy, from non-fossil fuel sources, is what we want. Solar cells don’t come cheap, but a recent discovery based on algae may change all this. Mark Nelson examines the process and its prospects. IND, wave and solar power opportunity to develop different types of solar Clever creatures each have their advantages and energy technology, and it’s likely that several Regular readers of this magazine will, Wprotagonists, and while wind and forms will ultimately all find uses, depending of course, know already that diatoms are waves come and go, there’s always light on the situation.” clever creatures and have other scientific (for half of the day in most places). Bright Dye-sensitized technology, for instance, uses applications. Back in 2007 we reported how sunlight is not essential for electricity environmentally benign materials and works Prof. Ken Sandhage from the Georgia Institute generation from solar cells; average daylight well in lower light conditions, he continues. of Technology was using diatoms to create gas is good enough for efficient ones. So why And the new findings offer advances in sensors able to detect pollution more rapidly don’t we make more of PV (photovoltaic) manufacturing simplicity and efficiency. and efficiently than conventional devices. technology, to use the proper name? Researchers in Georgia had created a new In a word (or two), cost-effectiveness. PV Different approach class of gas sensors based on diatoms, using power is expensive: efficient solar cells are “Dye-sensitized solar cells already exist,” a chemical process that converts the shells’ too expensive for most applications and cheap Rorrer said. “What’s different in our approach original silica (silicon dioxide, SiO2) into the solar cells are inefficient. An effective array are the steps we take to make these devices, semiconductor material silicon. The converted of cheap solar cells tends to be very bulky and the potential improvements they offer.” shells, which retain the 3D shape and and while this is not a problem for some The new system is based on living diatoms, nanoscale detail of the originals, could also be applications, it’s hardly an elegant or universal which are extremely small, single-celled useful as battery electrodes, chemical purifiers solution. algae, which already have shells with the and in other kinds of application requiring nanostructure that is needed. They are allowed complex shapes that nature can produce better Pinball wizards to settle on a transparent conductive glass than humans. Before solar cells can take centre stage surface, and then the living organic material is There’s no shortage of designs in this for power generation something has to removed, leaving behind the tiny skeletons of marine Meccano set, either. be done to improve their cost-efficiency the diatoms to form a template. According to the Aquatic Microbe Forum, ratio and nobody imagines this can be an A biological agent is then used to some 100,000 species of diatoms exist in overnight discovery. Scientists the world precipitate soluble titanium into very tiny nature, and each forms a microshell with over are working on this ‘holy grail’ project ‘nanoparticles’ of titanium dioxide, creating a unique and often complex 3D shape that and currently one of the most interesting a thin film that acts as the semiconductor for includes cylinders, wheels, fans, doughnuts, developments comes from researchers in the the dye-sensitized solar cell device. Steps circles and stars. Sandhage and his research Pacific Northwest in the USA. that had been difficult to accomplish with team have worked for several years to take Engineers at Oregon State University have conventional methods are made easy through advantage of these complex shapes by discovered a way to use an ancient life form the use of these natural biological systems, converting the original silica into materials to create one of the newest technologies using simple and inexpensive materials. that are more useful. Since scientists already for solar energy. Even better, their systems “Conventional thin-film, photo-synthes- know how to culture diatoms in large volumes, harnessing the diatom genetic code may be significantly simpler to build than ising dyes also take photons from sunlight could allow mass-production of complex and existing silicon-based solar cells. and transfer it to titanium dioxide, creating tailored microscopic structures. The key to their discovery is diatoms, electricity,” explains Prof. Rorrer. “But in Says Sandhage, “Diatoms are fabulous or rather the shells of these marine algae. this system the photons bounce around more for making very precise shapes, and making Diatoms are tiny, single-celled life forms that inside the pores of the diatom shell, making the same shape over and over again by a have existed in the oceans for at least 100 it more efficient.” reproduction process that, under the proper million years. The basis for much of other life growth conditions, yields microshells at a in the oceans, they possess rigid shells that can Confession time geometrically-increasing rate. Diatoms can be used to create order in a natural way at the Rorrer is honest enough to confess that produce three-dimensional structures that extraordinarily small level of nanotechnology. the physics of this process are not fully are not easy to produce using conventional By using biology instead of conventional understood. Nevertheless, it definitely silicon-based processes. The potential here is semiconductor manufacturing approaches, works. More so than materials in a simple flat for making enormous numbers of complicated researchers at Oregon State University and layer, the tiny holes in diatom shells appear 3D shapes and tailoring the shapes genetically, Portland (Oregon) State University have to increase the interaction between photons followed by chemical modification as we have created a new way to make ‘dye-sensitised’ and the dye to promote the conversion of conducted to convert the shells into functional solar cells, in which photons bounce around light to electricity, and improve energy materials such as silicon.” as if in a pinball machine, striking these production in the process. dyes and producing electricity. Although this Diatoms are ancient, microscopic organ- Puzzle find technology may be slightly more expensive isms that are found in the fossil record as far Changing subject, if you’re a seasoned than some existing approaches to making dye- back as the time of the dinosaurs. They are a visitor to amateur radio rallies, you’ll know sensitised solar cells, it has the potential to key part of the marine food chain and help how the strangest things can turn up for sale. triple the electrical output. cycle carbon dioxide from the atmosphere. Vibrators for generating alternating current But in recent years their tiny, silica shells from battery supplies are not uncommon End of the road for silicon? have attracted increasing attention as a way finds at these events, but the recent Dunstable “Most existing solar cell technology is to create structure at the nano level. Nature Downs electronics boot fair had some based on silicon and is nearing the limits of is the engineer, not high-tech tools. This is externally driven vibrators. Does any reader what we may be able to accomplish with providing a more efficient, less costly way to know how these worked and what kind of that,” says Greg Rorrer, an OSU professor of produce some of the most advanced materials drive was required? And no, I didn’t buy one chemical engineering. “There’s an enormous in the world. of them!
22 Everyday Practical Electronics, August 2009 FREE £7.99 CD-ROMELECTRONICS TEACH-IN 2 FROM THE PUBLISHERS OF USING PIC MICROCONTROLLERS A practical introduction Breadboard layouts to aid understanding Free software on CDROM Simple programmer project Free PIC Toolkit software Everything you need PIC N’ MIX to get you started PLUSPL U S PIC N’ MIX A hhost of practical Teach- nics In 2 programming and ro
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23/03/2009 11:39:27 ELECTRONICSdd 1 TEACH-IN 2 now on sale in WHSmithss or available direct from us:s: 01202 873872 £9.50 www.epemag.com Including UK P & P Constructional Project
Simple Data- Logging Part 2 – Weather by Glenn Pure
Station This month, we get into the nitty-gritty of building it – all the mechanical detail and then the actual construction.
Y NOW, we’ve hopefully whetted " To keep the design simple and Byour appetite with this simple the same time positioning the opposing maximise reliability, a magnetic reed design. Most of the mechanical detail side under the funnel outlet, where it switch, mounted on a bracket next to here is ‘roll your own’, but there is an the tipping bucket, was used. alternative commercial rain sensor The tipping back and forth can be The switch is closed by a tiny ‘rare- available if you don’t have the time detected in various ways. Since power earth’ magnet (measuring only 3 × or inclination to make one – see later. consumption was important for this 2mm) that is mounted on the tipping For those who do, read on! project, a passive sensing mechanism bucket. As the bucket swings, the was chosen. This involves momen- magnet moves past the reed switch, Rain sensor tarily closing a switch each time the closing it for a brief moment. The rain sensor uses a tipping bucket bucket tips. As shown in the circuit A similar mechanism is found in mechanism, consisting of a rain col- diagram last month (Fig.1), the switch many commercial rain sensors, and lection funnel that feeds water into a (S3) closure pulls the rain sensor line because the reed switch is glass-sealed, pivoting bucket divided into two op- low (it is normally held high by a it has the advantage of being practically Ω 24 posing halves. When one side of the 220k pull-up resistor). Everyday immunePractical to Electronics, moisture and August corrosion. 2009 Constructional Project
The main funnel is glued using silicone The water then passes into a secondary Under the secondary funnel is the sealant into a 100mm PVC pipe end funnel, mounted on a U-shaped bracket 5% 5 & * 5 cap, which has its end removed. Note ! 5 J= with water and tips when it gets too the mesh leaf and insect trap on the end cap. You can see this end cap in heavy. A magnet on the tipper trips bottom end. ! a reed switch to indicate one ‘fill’. To achieve its light weight and according to the plan shown in Fig.4. the bucket supports (containing the non-magnetic properties, the tipping For accurate cutting, use a utility knife axle holes) back down against the body bucket and its mount are made from to score the sheet repeatedly, then bend of the bucket. Keep the bend sharp, for 0.7mm thick aluminium sheet. You it back and forth along the score line to example by clamping along the bend may well have some of this in your snap it (bending it only 10° or so each line in a vice. junk box, salvaged from those utility way is enough). Practise on a scrap Next, shape the main body of the boxes that come with both an alu- piece – you will quickly get the idea. bucket by bending it over a tube or minium lid and a plastic one. Next, very lightly score a line along rod about 25 to 30mm in diameter. The only problem with using this the centres of the drill holes. Continue A broom handle works well, as does sheeting is that it is work-hardened, this line across the whole width of the some one-inch diameter PVC pipe. " sheet, as it is useful later when centring Make sure the result is symmetrical ! " " and mounting the divider between the and even in shape, both lengthways heating, which will anneal the alu- two halves of the bucket. and sideways. The aluminium should minium and make it much easier to Drill the holes now, as it is a lot be quite soft and easy to reshape if shape. I used a blow torch for maybe easier before the bucket is bent into necessary. ]; >; % - shape. The holes for the axle in the Finally, cut a divider to separate stantly moving over the piece. tipping bucket should be very slightly the two halves of the bucket. The Do not heat it so that it starts to larger than the axle, and located as width of the divider will depend on glow. If you don’t have a blowtorch, marked on the template. It’s important the diameter of the rod used to shape try sitting the sheet on an electric stove that the axle sits close (a millimetre the bucket. (solid) hotplate for a minute or two. or two) below the bottom of the main The divider is ‘glued’ into place using body of the bucket, as this makes for a small amount of silicone sealant or Tipping bucket more sensitive operation. epoxy. It’s a good idea to include nar- However, before annealing the Now anneal the sheet, then proceed % J % # sheet, mark out and cut the bucket to bend it into shape. Start by bending the sides of the divider to help glue it in
Here’s the way the magnet is mounted Another close-up of an important part: Once the bucket has tipped and the 5% the plastic washer which stops the water measured, it needs to escape. 5 bucket mechanism fouling the mounting These mesh-covered holes in the pipe bracket. Without this, the readings may end cap are for that purpose. Note the bucket. be erroneous. measurement for the two screw holes.
Everyday Practical Electronics, August 2009 25 Constructional Project
0.6-0.8mm 30 magnet aluminium sheet hole (3.5mm) 4 4mm fold lines hole bend axle axle down 180o hole hole hole for tieing
80
12 off cable to cL 25 reed switch axle 28 hole 15 45 65 32 outside width of bucket +4mm bend to semicircle TIPPING BUCKET BRACKET TEMPLATE TIPPING BUCKET TEMPLATE
flange divider on bend flange 3-4mm end open centre line 90o to back (magnet) inside height bend flange of tipping 90o to front bucket (axle under) (axle) plan elevation inside width of tipping bucket end open TIPPING BUCKET DIVIDER TEMPLATE TIPPING BUCKET ASSEMBLED
Fig.4: follow this diagram to make the tipping bucket assembly for the Simple Data Logging Weather Station. place (see template). Once the glue has Axle and bracket the axle. Avoiding such play will keep set, smear a thin bead of silicone sealant The tipping bucket pivots on a thin the magnet on the bucket positioned a along the edge of the divider, where it axle. For this, a short length of stain- constant distance from the reed switch meets the inside of the bucket, to ensure less steel wire (1.4mm in diameter) was each time it swings past. A distance of % % used, although galvanised steel wire about 3 to 4mm should be the target bucket to the other. A cotton tip from % " " " ! (face of magnet to centre axis of reed the medicine cupboard will do the trick. isn’t critical. The wire was obtained switch). Adjustment of the bracket to Minimise the amount of silicone applied, from the whisk part of a stainless steel achieve the correct spacing is made by but apply it to both halves of the bucket egg whisk. simply bending it. to better balance the two sides. A bracket to mount the tipping If the magnet is too close, the force The rare earth magnet can now be bucket on its axle can now be made of attraction between it and the reed glued into the locator hole on the up- from another piece of aluminium sheet % " per side of the tipping bucket – see (don’t use steel sheet as it is magnetic). tipping bucket to lock in the centre Fig.4 and photo. Again, drill the holes in this for the position. If the gap is too great, the reed 7 axle before bending. switch simply won’t close. The spacers the tipping bucket. When it is in op- The exact dimensions of the can be cut from the end of the plastic eration, it appears to empty more ef- bracket will depend on the width ink tube of a ballpoint pen. of the tipping bucket. Precision surface of the bucket is water repellent. isn’t necessary, since washers or Reed switch This can be achieved by coating it spacers should be used to keep The reed switch is glued to the with a silicone car polish. Don’t be the tipping bucket away from outside of the bracket that holds the tempted to smear a thin coat of sili- direct contact with the bracket, en- tipping bucket. Be aware that the cone sealant as this tends to be sticky suring an unimpeded tipping action. part of the reed switch that is most Such spacers (or washers) are also sensitive to the magnet is either end of impeding the proper operation of the important to ensure minimum side- the switch, not the middle of it. There- tipping bucket. ways play of the tipping bucket on fore, ensure the reed switch is mounted
26 Everyday Practical Electronics, August 2009 Constructional Project
MATERIAL: 0.4mm GALVANISED STEEL SHEET
RADIUS 180mm
RADIUS 12mm
MAIN FUNNEL TEMPLATE (50% ACTUAL SIZE)
Fig.5: these two templates will help you SECONDARY FUNNEL make your main (primary) and secondary TEMPLATE funnels. The main funnel catches the rain, (ACTUAL SIZE) MATERIAL: 0.6 –0.8mm the secondary funnel directs it into the ALUMINIUM SHEET tipping mechanism. Note that the main RADIUS 50mm funnel template needs to be blown up 200% when photocopying, otherwise it will be a tad too small! The overlap when you bend the funnel shapes should be about 8mm. Seal RADIUS 3mm this overlap with silicone sealant. so the magnet swings past one end (see After bending, it was held in shape By mounting the funnel this way, Fig.6). A separation of 3 to 4mm between with pop rivets, then the join was it will slip nicely over the end of the the magnet and the reed switch is best. soldered up, although silicone seal- pipe and be held in place by gravity. Care is needed when soldering wires % " = A hole tapped into the pipe and a to the reed switch, since it appears to wire gauze was then bent and glued machine screw can always be added partly melt at soldering temperature. over the bottom end of the funnel. to make sure it doesn’t move. Hence it is essential to use a good heat- The gauze was scavenged from a A small secondary funnel has also sink between the switch and the end of frying pan cover – the type used to been included. This sits between the % " stop fat spattering. Two-part epoxy main collection funnel and the tipping with a pair of needle-nose pliers will % " bucket and enables the rain collected achieve this). glue this in place. from the main funnel to be aimed Once soldered up, the switch and ! accurately into the tipping bucket connections should be covered with pipe, use a PVC pipe end cap. Cut the mechanism. sealant to waterproof them, since the end out of this cap, effectively leaving connecting wires on the switch are only the side wall, which now forms made from steel and will corrode over a ‘plastic ring’. time if they get wet. Fix the funnel into this ring with acrylic or silicone sealant. Since nei- Rain funnels ther of these sealants will stick very Just in case you haven’t come across The tipping bucket is housed inside well to the PVC, it’s a good idea to run a one before, this is a glass-encapsulated a length of 100mm diameter PVC sewer bead of epoxy around the inside of the magnetic reed switch of the type used = ring, after the sealant has cured. Make in this project. Its contacts are normally to the top end of the pipe. The funnel sure there is no sealant or glue fouling & 5 5 ] was made from thin (0.4mm) galva- the inside of the PVC ring, otherwise it most sensitive areas of a reed switch are nised steel sheet (see Fig.5). won’t slide onto the pipe later. towards each end.
Everyday Practical Electronics, August 2009 27 Constructional Project
180
It’s best to make the sec- ondary funnel from annealed aluminium sheet, since this is much easier to bend into shape. Fig.6: here’s how the funnels and This funnel is held over the tip- the tipping bucket assembly all go ping bucket by a U-shaped bracket. together. Note that the magnet is It would be a good idea to coat the aligned with one end of the reed switch (not with its centre). inside surface of the secondary funnel, so that it is also water repellent (as you did for the tipping bucket surface). The tipping bucket itself, along with the PRIMARY secondary funnel, is bolted onto another end (MAIN) FUNNEL SILICONE cap, which slips onto the bottom of the PVC SILICONE SEALANT SEALANT pipe. The two are mounted together to keep “GLUE” them in good alignment. “GLUE” Two M4 × 20mm long screws (with locking nuts) have also been tapped into the end cap and sit underneath each half of the tipping bucket (see 140 photo). They are used to adjust the amount the bucket will hold before it 100mm PVC PIPE tips. Brass or stainless steel machine CAP WITH screws (M4) and nuts should be used 95mm HOLE throughout for corrosion resistance. ALL There are two larger holes oppo- MOUNTING DIMENSIONS BRACKET IN site one another near the edge of the MILLIMETRES end cap. The holes should be about 12 to 15mm in diameter and are the exit POP RIVETS points for the water from the 150mm LENGTH tipping bucket when it emp- # COVERED 100mm PVC PIPE ties. Make sure the outside of these holes are also WITH MESH % % [ TO PREVENT SPIDER/INSECT that insects or other debris cannot get inside the OR LEAF sensor and foul the mechanism. INGRESS 12 # Calibration 5 50 5 Once the sensor is assembled, calibration can then be done. Make sure the end cap is placed on POP RIVETS a level surface before starting. Calibration is done 7 by slowly dripping water into the primary or sec- MAGNET ondary funnel and measuring how much it takes 3mm DIAM, SECONDARY before the bucket tips. SECONDARY 2mm LONG FUNNEL Do this 10 or 20 times and average the results. 3–4mm Aim for about 5ml each time, using the adjustment CLEARANCE 15mm WIDE % " # FROM FACE STRIP OF OF MAGNET the tipping point. Ensure the same amount of 0.4mm TO CENTRE THICK water is needed no matter which direction the OF REED GALVANISED SWITCH bucket is tipping. STEEL 88 To convert the amount needed to cause the SHEET 12–15 END OF " REED SWITCH the diameter of the top of the primary funnel in ALIGNED TO DIVIDER CENTRE OF centimetres then calculate the area of this open- MAGNET ! " % to get the radius, square this value then multiply TIPPING 100mm BUCKET 12.5–15 by π (ie, 3.1416)). PVC PIPE RADIUS REED SWITCH The area in square centimetres will be the FRICTION (GLUED TO CAP BRACKET) number of millilitres of rain the funnel will collect AXLE for every 10mm of rainfall. You will get a value BRACKET FOR 4mm DIAM WASHERS TIPPING of about 250ml for a 180mm diameter funnel, or HOLES about 25ml per mm of rainfall. If it takes 5ml to BUCKET " ; > DRAIN rainfall for each bucket tip. 60 DRAIN HOLE# HOLE#
28 Everyday Practical Electronics, August 2009 Constructional Project
Electronics sensors and weatherproof the electron- sensors don’t need to be connected. housing ics is needed. You will need an accurate means of A star picket, commonly used for measuring 24 hours to within a second We showed the electron- fencing was used. These have conven- or so. A handheld GPS or good quartz ics ‘box’ in Part 1 last month. ient pre-drilled holes, through which wristwatch will do the job. However, it needs to be housed brackets made from bolts and steel = so that it is protected from the strips can be mounted. The photos the internet. You will have to use one elements. illustrate how to make these up. that gives a seconds reading and auto- A ‘case’ can be made from the The mount for the rain gauge is con- matically increments this (for example, same 100mm PVC pipe and a friction- structed so that it can be tilted on two try www.timeanddate.com). axes, enabling the sensor to be levelled First, reset the controller using the gauge. However, in this instance, I % $ " Reset button. With the case open, elected to use only a top cover, leav- the sensor, on which the tipping bucket press the clock correction switch (S2) ing the bottom open to the elements is mounted, should be set so it is level, momentarily and note the exact time ‘just in case’ something leaked and it otherwise accuracy will be degraded. it was pressed. % % By the way, I haven’t done a check to The LED will come on as soon as The ‘electronics’ box is not secured see how accurate the rain gauge is, but the switch is closed and stay on for to the pipe; rather it hangs from a sim- commercial units of this type are typi- four seconds to indicate that the clock ple metal bracket mounted on the pipe cally accurate to within a few percent. correction process has successfully top cover. The cabling simply drops As indicated above, the control box started. Note that the clock correction out of the bottom of the case. switch will be disabled 30 minutes All cabling must be secured to star +|` % after a reset (assuming the controller pickets or to some other mounting % # ! # has been programmed with a 30 minute pole – a cable dangling in the breeze with a metal bracket bent up from a logging frequency). is too much of a temptation for curious piece of sheet metal. A second bracket At the same time the next day, about wildlife and household pets! is attached to the plastic box, so that 20 seconds before 24 hours has elapsed, it can be hung in place – see photos. the LED will come on. At exactly 24 Mounting the sensors hours, press the clock correction switch and the controller Initial set up again. The LED will turn off and the Most of the hard work is now almost The only job to do is to perform the correction value will be stored. This completed. The main job left to do is clock correction if accuracy better than value is stored in the PIC in non-volatile to assemble and mount the bits and " memory, so is retained even if power pieces. Since this is designed for use First, start the weather station by is removed from the PIC. in remote locations, it is assumed that inserting three AA batteries into the If you forget to press the switch, the a quick and simple way to mount the battery clip. The temperature or rain LED will turn off after about 40 seconds,
Parts list (louvred housing) All sheet metal used is 0.4mm thick galvanised steel (0.6mm thick aluminium is preferable for the louvres themselves but is harder to obtain). Sheet metal 1 170 × 170mm (top cover) 1 150 × 150mm (top) 5 400 × 25mm (louvres) 4 110 × 20mm (corner supports – you should use galvanised steel for strength to make these, even if you do make the louvres from aluminium sheet) Other 30 small pop rivets (to fix louvres to corner supports) 3 M4 × 30mm machine screws and nuts 3 M4 × 20mm tapped spacers 1 mounting bar made from aluminium channel (12 × 12mm), approx 150mm long (for mounting the housing) 2 6-8mm long pop rivets (for mounting bar) 1 50 × 8mm bolt, head cut off, with nut and two washers to suit (for mounting bar) Parts list (rain gauge) 1 360mm square sheet metal (main funnel and bucket parts, U-shaped bracket) 1 100mm diameter semi-circle 1 150mm length of 100mm diameter PVC pipe with friction caps Reproduced by arrangement 1 magnetic reed switch with SILICON CHIP 1 3mm diameter × 2mm rare earth magnet magazine 2009. Various screws, pop rivets and scraps of metal www.siliconchip.com.au
Everyday Practical Electronics, August 2009 29 Constructional Project
Making The Temperature Sensor Housing
For accurate readings, the location If the housing itself gets hot, then resistance to radiant heat from over- of the temperature sensor is impor- it can heat air that passes through it head, four vertical corner supports tant. It must be placed so that it is not and cause an incorrect reading at the and five louvres made from bent sheet affected by radiant heat from the sun sensor. Therefore, the housing should metal which fix directly to the corner or other direct heat sources. It should be painted white so as to minimise the supports. The easiest way to assemble also not get wet, as evaporation would absorption of radiated heat. It must also the housing is with pop rivets. A piece cool a wet sensor – yet there should be be designed to reduce the chance that of aluminium channel is also pop riv- free air movement around the sensor the housing itself will create localised eted or bolted on to the inner top cover to enable it to be at equilibrium with heating or cooling of the sensor that’s for mounting the whole assembly. the current air-temperature. different to the current air-temperature. To achieve the right conditions, A louvred housing can be made Construction professional weather stations usu- relatively easily from thin sheet metal. Commence construction by cutting ally include a louvred housing that Aluminium sheet about 0.6mm thick is out all the sheet metal parts (see photo). is typically mounted a fixed height ideal for ease of handling, low thermal The dimensions for these parts are above ground level (1.25 metres is mass and weight, but it may be hard given in the parts list on the previous apparently the international stand- to obtain. If this isn’t available, use page. Don’t bend any of the parts yet. ard). The housing shades the sen- 0.4mm galvanised steel sheeting. It’s a good idea to drill the holes that will sor and stops it getting wet, while The housing design consists of a be needed for assembly now, since this allowing free air flow. top, a top cover over this to improve is easier to do on flat (unbent) sheet.
It’s not a template, but this photo can be used as a cutting and Here are the components for one side of the housing – the largest drilling guide for your temperature sensor housing. piece is the top cover, the four pieces below are side guides.
Here is that first louvre fixed to the four side supports. Once A few minutes later and all louvres are fitted, now ready for the you have achieved this, the rest is easy! top cover to be fixed in place.
30 Everyday Practical Electronics, August 2009 Constructional Project
Start with the top and top cover. the corner supports so its top edge aligns 12mm aluminium channel – see First, tape them together in accurate with the 10mm line (see photo). below left. This makes it fairly alignment and drill three holes (4mm The easiest way to drill the corner straightforward to fit a bolt to the dia.) as shown in the photos – this will supports is to clamp a short length other end (an 8mm dia. bolt will fit ensure that the holes in the top cover of scrap timber (19 × 42mm cross- easily in the channel). align with those in the top when you section) to the work bench so it The easiest way to hold the bolt in come to screw the top cover on. Four protrudes from the bench. Hold the place is to put it in a vice and crush holes for pop rivets can also be drilled corner support with a large bulldog the top edges of the channel over in the top – see photo below left. clip while the louvre is placed over the bolt shaft (see photo). Two-part Pop rivet holes can also be drilled in it and the hole is drilled (see photo). epoxy will ensure it stays in place. the louvres. Don’t drill any holes in the The next louvre up can now be pop- Next, rivet the mounting bar to corner supports though. Now bend the riveted into place, aligning its top edge the inner top cover, after first cut- top and top cover into shape, as well with the next mark 20mm along the ting away a portion of the channel as bending the corner supports and corner support. Fix the remaining lou- so that the mounting bar will sit flat louvres as shown in the photo below. vres into place. When all the louvres are on the cover. The prototype louvred Mark lines at 20mm intervals along fixed, the top can be pop riveted on. The housing shown in the photos in Part the corner supports (these will be used top should slide nicely over the upper 1 had the mounting bar fixed under to align the louvres). The last line marked ends of the corner supports if you have the top cover, but this is clumsy so will be only 10mm from the end of the measured, cut and bent accurately. don’t try it. Now fix the top cover corner support and is where the first The housing is now almost finished. in place with machine screws and (bottom-most) louvre will be mounted. It’s now time to make the mounting spacers. Drill and pop rivet the bottom louvre to bar, which is made from a piece of Finally, the housing should be painted white to minimise absorp- tion of radiant heat. A can of fast drying spray paint is the easiest way to do this. Remember that several light coats are better than one heavy coat. The temperature sensor (IC5 – see Part 1, last month) itself is mounted on short lengths of wire that are suspended from the corner supports of the louvred housing (simply bend them around the top of the corner supports between the top and the first louvre). The sensor should be mounted in about the centre of the louvred housing and can be held in place with a twist tie or short length of wire. Make sure it Drilling holes in small, thin bits of metal Here we are preparing the first louvre, can’t drop out when left unattended is not only tricky, it can be dangerous if ready for securing to the corner support for a lengthy period. you don’t properly clamp and support with a pop rivet. the work.
The mounting bar is made from a piece of U-shaped (channel) aluminium with an 8mm bolt crushed in position then secured with two-part epoxy. This is then secured to the (inner) top cover with pop rivets. The outer top cover, which helps prevent the housing from heating up and giving false readings, is mounted 12mm above the inner top cover by means of 12mm threaded nylon standoffs An upside-down finished view of the housing. The four stiff so there is no heat conduction from one part to the other. wires inside the housing support the temperature sensor.
Everyday Practical Electronics, August 2009 31 Constructional Project
Data is transmitted in text form as comma-separated values that can eas- ily be imported into spreadsheets. A total number of data points recorded since the last reset. The weather station does not record the time directly. You will need to calculate the time of each data record based on the time the weather station was reset (or powered up) and the log- ging frequency. Don’t forget that the logging period after the weather station is started. Error detection Some basic error detection is also Left: the controller box inside its PVC 5 5% ! built into the software. When each data as shown above. The pipe mounting record is written, the value 255 (deci- ! * mal) is also written to all four bytes of moved at will. the next record. During a data dump, if the weather but no correction value will be recorded it to be plugged in and unplugged even station software encounters these and the controller will simply resume when the weather station is operating. values, it will transmit the following normal operation. If the rain sensor is left unplugged or text string ‘BREAK’ then ‘NULL’ on is faulty, zero values will be recorded the next line. Logging weather data for temperature. Since data only up to the last valid Set up the rain and temperature sen- There is nothing else to do, except record are normally transmitted, such sors, power up the weather station, and come back in a month – or a year – and a BREAK will never be seen during a reset it. Make a note of the time and date download the data. normal dump operation. It will occur % ! if there was a power down and power data will be recorded 30 minutes (or Downloading the data up, or an internal reboot of the weather one logging frequency) after the reset. Downloading data is straightfor- station while it was operating. The rain and temperature sensors can ward. Instructions are printed on the A reboot will occur if the software de- be plugged in at any time, although, front label of the weather station (see tects some abnormal conditions during obviously, nothing will be recorded Fig.7). Freeware data-logging software operation, such as a suspicious looking until they are. is used to receive the data (see below) interrupt. It can also occur if the inter- Even though the temperature sensor on your computer or laptop. This nal record counter becomes corrupted, is a programmable digital device, the % % % although this is unlikely. software in the weather station enables you nominate. An entire dump of the weather station’s data can also be performed. This will show a ^ '= % recording following the most recent reset. BREAKs may also be seen further into the data record from some ear- lier resets (only those that weren’t overwritten since the last reset). Performing a full data dump of the entire EEPROM contents is easy. Simply do a reset on the weather sta- tion just before doing a data dump. A sample spreadsheet (Fig.8.) is attached showing weather data recorded in the author’s backyard in Can- Fig.7: full-size front panel artwork for the Data Logging Weather Station. berra. Some plots of the data are also shown, including
32 Everyday Practical Electronics, August 2009 Constructional Project
Fig.8: an Excel spreadsheet from the author’s installation. Because the data from the Weather Station is virtually ‘universal’ in format, it can be used in a wide range of applications. a very heavy rain event where about minutes. Setting LOG_FREQ to 30 post than the (tiny) items are worth. 50mm fell in 30 minutes. The rain gauge (decimal) and HRS24 to 48 (decimal) % is able to handle both heavy and light will give a 30-minute logging fre- % - rainfall events, although you can expect quency and a normal 24-hour clock. vide them for a nominal shipping problems with extremely heavy rain or Logging frequencies down to one ` % " hail storms. minute are possible, but the HRS24 (www.evans-pure.net/weather.htm). value can only be a maximum of 255. Alternatively, you may be able to Changing logging frequency The only thing HRS24 affects is the scrounge a suitable magnet or two ! % % frequency with which clock error cor- from, say, an old hard disk drive. Most for a 30-minute logging frequency, rection occurs (including the initial reed switches are quite sensitive and meaning rain and temperature will setting of the clock error). will work with most magnets. The be recorded every 30 minutes. The So, if LOG_FREQ is set to 1 and advantage of the ‘rare earth’ magnets logging frequency can be changed by Z $>_ >\\ + ` % used here is their incredible size-to- % clock correction value every LOG_FREQ power ratio. this and reprogramming the resultant x HRS24 minutes (ie, 1 x 255 minutes). + ` Similarly, performing an initial Commercial rain sensor ! % + ` clock calibration will complete 255 For those who don’t want to make % - minutes after it is started, not 24 their own rain sensor, a commercially stants near the start: hours later. available sensor is available for about ; $ LOG_FREQ EQU D’6’ ; Frequency Obtaining parts and software (minutes) with which data is logged " The data logging software is available HRS24 EQU D’240’ ; = " + ^ $ from www.eltima.com/products. Down- (No of minutes in 24 hours)/LOG_FREQ website: www.peetbros.com. You will load the freeware ‘RS232 data logger’ % ` % under ‘serial port software’. " logging frequency. The above exam- Buying the magnet ‘mail order’ is a ple shows a logging frequency of six case where it costs far more to pack and % % EPE
Everyday Practical Electronics, August 2009 33 STORE YOUR BACK ISSUES ON CD-ROMS FIVE YEAR CD-ROM NOW AVAILABLE MIDI DRUM KIT - 1 WIN A 546 different drum sounds MICROCHIP PICDEM PIC CARILLON Use with a computer or synthesiser MC DEVELOPMENT Up to seven instruments at one time BOARD Want to be a bell-ringer? Precussion plate, hand plate and foot activationSTANDBY POWER SAVER PIC Controlled LCD shows sensor, patch and volume settingsSave power – remotely turns Four octave range off TVs/DVDs/Amplifiers etc. Synthesised bell sounds CALLTEACH-IN ALERT 2008 PHONE/FAX MISSED Using PIC microcontrollersV8 DOORBELLONLY Part Two – Programme Provides extra visualBasic and Commands Plus audible latchedSimple signalling LED Control VROOM! VROOM! SERIAL I/O CONTROLLER £16.45 & ANALOGUEPIC SAMPLER SPEECH SYNTHESISER(£29.95 FOR 5 YEAR) Add speech to your PIC projectseach including VAT and p&p A versatile easy-to-drive I/O controller for your PC JAN 2008 £3.75 INDUCTANCE & Q-FACTOR METER iPOD AND MP3 CHARGER Inductance from 200nH to 10mH Charge from a plug-packKK or car battery Q-Factor 1-120 (approx)DEC 2007 £3.75 TEACH-IN 2008 KKAutoranging mea Using PIC Microcontrollers – Part 3 PLUS BU ERR VOL 1: BACK ISSUES – January 1999 to June 1999 A great way to buy EPE Back Issues – our Plus some bonus material from Nov and Dec 1998 CD-ROMs contain back issues from our EPE VOL 2: BACK ISSUES – July 1999 to December 1999 Online website plus bonus articles, all the relevant PIC software links and web links. VOL 3: BACK ISSUES – January 2000 to June 2000 Note: no free gifts are included. VOL 4: BACK ISSUES – July 2000 to December 2000 Order on-line from VOL 5: BACK ISSUES – January 2001 to June 2001 www.epemag.com or by phone, fax, email or post VOL 6: BACK ISSUES – July 2001 to December 2001 VOL 7: BACK ISSUES – January 2002 to June 2002 BACK ISSUES CD-ROM ORDER FORM VOL 8: BACK ISSUES – July 2002 to December 2002 VOL 9: BACK ISSUES – January 2003 to June 2003 Please send me the following Back Issue CD-ROMs. VOL 10: BACK ISSUES – July 2003 to December 2003 Volume Numbers:...... VOL 11: BACK ISSUES – January 2004 to June 2004 Price £16.45 each, £29.95 for Five Year CD-ROM – includes VOL 12: BACK ISSUES – July 2004 to December 2004 postage to anywhere in the world. VOL 13: BACK ISSUES – January 2005 to June 2005 Name ...... VOL 14: BACK ISSUES – July 2005 to December 2005 Address ...... VOL 15: BACK ISSUES – January 2006 to June 2006 ...... VOL 16: BACK ISSUES – July 2006 to December 2006 ...... VOL 17: BACK ISSUES – January 2007 to June 2007 Post Code...... ! I enclose cheque/P.O./bank draft to the value of £ ...... VOL 18: BACK ISSUES – July 2007 to December 2007 ! please charge my Visa/Mastercard/Maestro £ ...... VOL 19: BACK ISSUES – January 2008 to June 2008 Card No...... VOL 20: BACK ISSUES – July 2008 to December 2008 Card Security Code ...... (The last 3 digits on or just under the signature strip) NEW – FIVE YEAR CD-ROM – Jan 2003 to Valid From...... Expiry Date ...... Dec 2007 Maestro Issue No...... NOTE: These CD-ROMs are suitable for use on any PC with a CD-ROM drive. They require Adobe Acrobat Reader (available free SEND TO: Everyday Practical Electronics, from the Internet – www.adobe.com/acrobat) Wimborne Publishing Ltd., Sequoia House, 398a Ringwood WHAT IS INCLUDED Road, Ferndown, Dorset BH22 9AU. All volumes include the EPE Online editorial content of every listed Tel: 01202 873872. Fax: 01202 874562. issue, plus links to all the available PIC Project Codes for the PIC E-mail: [email protected] projects published in those issues. Please note that we are unable to answer technical queries or provide data on articles that are Payments must be by card or in £ Sterling – cheque or bank more than five years old. Please also ensure that all components draft drawn on a UK bank. are still available before commencing construction of a project Normally posted within seven days of receipt of order. from a back issue.
Everyday Practical Electronics, August 2009 35 Constructional Project
Select the features you want in this
Fast Charger for NiMH batteries This is a truly versatile charger. It can charge up to 15 identical NiMH or NiCad cells. You can build it to suit any size cells or cell capacity and you can set the charge rate. It can fast charge, trickle charge and has safeguards, including temperature sensing, to prevent overcharging. TANDARD NiMH (nickel metal It can charge from one cell up to 15 To see why over-charging can de- Shydride) and NiCad chargers are cells simultaneously and battery packs stroy a battery pack, have a look at available just about anywhere, from up to 18V for both NiMH and NiCad Fig.1. This shows the typical voltage, hobby stores to supermarkets, the types. Charging can be set from just a temperature and internal pressure rise service station and even your local few milliamps up to 2.5A and it in- of a cell or battery pack with charge. chemist or newsagent. cludes a reliable end-of-charge detec- Once charging goes past the 100% However, they usually only charge tion, with extra safeguards included point, the temperature and internal two or four AA cells and at quite a slow to prevent over-charging. pressures rapidly rise and the voltage rate – typically, they will take between Safety is important when charging initially rises and then falls. four and 15 hours to charge. But what NiMH and NiCad cells and batteries, Continual overcharging will dam- if you want to charge at a much higher because they can be destroyed or have age the cells due to the elevated tem- rate, or more than four cells at a time? their life seriously shortened if the perature. This accelerates chemical Or cater for C and D type cells or bat- charger is left on for too long after the reactions that contribute to the ageing tery packs? battery pack has reached full charge. process. In extreme cases during over- The only complete answer is to build charging, excessive internal pressure the Fast NiMH Charger. by JOHN CLARKE can open their safety vents to release
36 Everyday Practical Electronics, August 2009 Constructional Project
Main Features U Designed for NiMH cells, but will handle NiCads too U Charging timeout U dT/dt (temperature change rate) for end of charge detection U Over and under cell temperature detection U Power, charging and thermistor indication LEDs U Adjustable charging timeout limit These 1500, 1700 and 1800mAh ‘AA’ U Adjustable dT/dt setting NiMH batteries were once considered Optional top-up and trickle charging ‘state of the art’. Now 2500mAh are U quite common (we’ve even seen claims U Adjustable charge current of 3000+ ‘AA’). Our new charger will Adjustable top-up and trickle charge currents handle these, as well as C and D type U cells and even battery packs. U Over-temperature cut out for charger the pressure. These vents will re-close after the pressure is released but the cells will already have been damaged. to the charger, in the knowledge that This could cause a false dT/dt end of they won’t be damaged but will be charge condition. Full charge detection absolutely ‘full to the brim’ when they To circumvent this, the dT/dt meas- Full charge can be determined in one are needed. urement for end of charge detection is of two ways. The conventional way Our new Fast NiMH Charger requires only enabled when the cell temperature has been to monitor the voltage across a small thermistor to be installed in the is at least 25°C. Should the thermistor the battery pack and detect the point battery pack or cellholder, in close end-point detection fail, a timer is where the voltage begins to rise rapidly contact with one of the cells, so it can included that will switch off charging and then fall. This form of end-point monitor temperature. The beauty of after a preset period. detection is called dV/dt (ie, change in this system is that it will recharge any Further safeguards to protect the voltage with respect to time). % cells are also included. Charging will In practice, the critical end-point can only partially discharged – but you not start, or will stop, if the NTC ther- " % will not over-charge it. mistor for the cells is disconnected particularly with NiMH cells. In fact, or if the temperature is under 0°C or dV/dt end-point detection with NiMH Cool safeguards over 55°C. Should the charger itself cells is neither safe nor practical. However, there is a proviso here, become too hot, charging will pause The only safe way is to monitor and it applies when you are charging and the temperature is measured after the temperature of the cells. Very few very cold batteries – they may rapidly two minutes to check if it has cooled chargers do this. rise in temperature during charging. This far more reliable method, es- pecially with NiMH cells, monitors the temperature rise of one or two 75 1.50 100 cells within the battery pack. Dur- ing charging the cells do not heat up much because most of the incoming 65 1.46 80 power is converted into useful stored energy. However, once the cells ) become fully charged, the charging 55 1.42 60 current (and power) is converted to heat, and so the cells quickly rise in temperature. This temperature change at the charg- 45 1.38 40 PRESSURE
CELL VOLTAGE ing end-point is called dT/dt – change (°C TEMPERATURE in temperature over time. The critical temperature rise is of the order of 2°C 35 1.34 20 per minute. This is where normal charg- ing should stop.
Some chargers, ours included, may 25 1.30 0 have a top-up charge after the end-point 0 50 100 to ensure full charging. After top-up, STATE OF CHARGE (%) the cells can be ‘trickle-charged’ to Fig. 1: typical charging curves for NiCad batteries (NiMH are similar). Cell maintain full charge. In this situation, temperature (green) and voltage (red) are most often used to detect the ‘end the cells are deliberately left connected point’ or 100% charge – in NiMH cells, the voltage is much less reliable.
Everyday Practical Electronics, August 2009 37 Constructional Project
dT/dt values. Full charge can be set from Specifications about 40mA up to 2.5A, while trickle Maximum input voltage...... 30V can be set from 10mA up to 500mA. Maximum charge current...... 2.5A Timeout can be set from between 0 to 25- hours, while dT/dt can be selected Charge current adjustment...... From 0 to 2.5A, corresponding to 0V to 2.5V TP4 using VR4 (in approximately 40mA from between 0.5°C rise per minute to at 5°C per minute. steps) More details concerning the adjust- Timeout adjustment ...... From 0 to 5 hours, corresponding to 0V to ments are included in the setting up 5V from VR1 at TP1. section of this article. 0 to 25 hour with x5 link installed (LK1) ...... LED status dT/dt adjustment ...... From 0.5 to 5°C rise/minute, corresponding Three LEDs indicate the status of the to 0.5 to 5V from VR2 at TP2. charger controller. The power LED is dT/dt measurement ...... Once every minute when cells reach 25°C or lit whenever power is applied to the more charger (obviously!) while the ther- mistor LED lights if the thermistor is Top up and trickle charge ...... Top up available when LK2 is installed. Trickle enabled when LK3 is installed disconnected, or if there is an over or ...... under-temperature detection. Trickle charge adjustment...... Adjustable using VR3 from 0 to 500mA, For over-temperature (>55°C), the ...... corresponding to 0V to 5V at TP3 &' % - ...... Adjustable in approximately 5mA steps ond (1Hz) while for under-temperature ;$` &' % Top up charge ...... 4x trickle setting for 1 hour two seconds (0.5Hz). Over heating of Cell over-temperature cutout ...... 55°C the charger itself causes the Thermistor Cell under-temperature detection 0°C &' Charger over-temperature cutout 50°C Finally, the charging LED is con- tinuously lit during the main charging Select the features you want and trickle charging if you want (no ex- cycle and switches off when charging In its simplest form, our Fast NiMH tra components are required) and set all is complete. Charger includes only the temperature the charge parameters: full charge cur- If top-up and/or trickle charging are detection feature. You can add top-up rent, trickle charge, timeout period and &' %
A view inside the NiMH Fast Charger. As you can see, the PC board sits in the bottom of the diecast box, as normal. But when the lid is screwed on, it becomes the base and the whole thing is turned over so the PC board is actually upside-down.
38 Everyday Practical Electronics, August 2009 Constructional Project
7–30V POWE R D2 1N 4004 DC IN REG1 LM317T A K IN OU T S1 CO N2 ADJ 120 10 F TP +5V 470 + TO 16V BATTERY 220 F TPGN D A – 220n F 50V VR6 POWE R LED1 500 +5V K A 100n F 100 F D1 TP1 14 16V TIME 1N 5822 VR1 17 Vdd OU T AN 0 K (5V=5h) 10k 8.2k TP2 9 5 8 D RB3 1k Q1 T/ t VR2 2 IC2 7 G AN 3 IRF540 (5V=5° C/ min) 10 F LM358 10k 1k 6 K S TP3 16V 4 ZD1 16V TRICKLE VR3 18 AN 1 (5V=500mA) LK1 1W A 10k 12 1k TIMEOU T IC1 RB6 9.1k TP4 PIC16F88- LK2 0.22 10 TOPUP I/ P RB4 5W CHARGE VR4 1 AN 2 EN ABLE +5V (2.5 V=2.5A) D1, D2 10k LK3 11 TRICKLE CO N1 RB5 EN ABLE OU T CE LL/BATTERY VR5 TP5 A K TEMP 47 20k ZD1 3 AN 4 470 8 A K TH1 RB2 ADJ 100n F LM317T 10k OU T IN 470 13 7 AN 6 LEDS RB1 D A A HEATSINK THERMISTOR CHARGE K TH2 TEMP Vss LED2 LED3 A G 5 K K IRF540 D S NIMH BATTERY CHARGER Fig.2: the circuit is based on a PIC16F88 microcontroller, and apart from the components used to set and monitor the current, there’s not much more to it. at 1Hz during top-up and at 0.5Hz the voltage across the thermistor is supply via a 9.1kΩ resistor. This restricts during trickle charge. Note that if the 2.5V at 25°C. adjustment to a nominal 2.5V maximum &' The voltage across the thermistor > \= &' % " =_ J The voltage inputs are all converted that charging has paused or stopped. `] _Ω resistor and a 100nF % `] ! settings can be processed in software. Circuit details remove radio frequency (RF) signals ! !+] !+> !+J !+_ The full circuit diagram for the Fast and noise that could be present due TP5 are provided for setting the trim- NiMH Charger is shown in Fig.2. The to the thermistor being connected pots when using a multimeter. There is circuit is based around a PIC16F88-I/P remotely from the circuit. also a TP GND terminal for the negative `] = ! =_ probe of your multimeter. % `] converted into a digital value and the The voltages measured at each test there is not much else to it. values are compared against the over Two NTC thermistors are used in the and under temperature values and for | ] circuit. NTC stands for ‘negative tem- dT/dt changes. _| !+] % ! | ] | > | J four hours. that the resistance of the thermistor ! The timeout value can be multiplied is progressively reduced as the tem- trickle charge values. The wiper of " &] perature rises. =; is inserted. This ties pin 12 to ground. Thermistor TH1 monitors the cell =J =] &] ]> {\| or battery pack being charged. It is these inputs can receive between 0V via an internal pullup resistor within connected via a 2-way terminal block \| `] ] (CON1) and forms a voltage divider the trimpot. & &> &J % with 20kΩ trimpot VR5 across the 5V For the full charge current input at &> " # supply. Preset VR5 is adjusted so that => | _ {\| &J "
Everyday Practical Electronics, August 2009 39 Constructional Project
the charger to heat up more than nec- essary. For example, at 2.5A and with S1 CHARGE POWE R THERMISTOR 10V higher than the battery voltage, LED3 LED1 LED2 there is going to be 25W dissipated ! % - 47 TP tainly become hot and the charger will TO GN D 9.1k THERMISTOR shut down when it reaches 50°C. So
TH1 358
IC2 you may have to reduce charge current CON1 10 F
LM
470 470 470 VR5 VR2 VR4 20 k 10 k 10 k if the supply voltage is high compared 1k 100nF TP2 D1 TP5 TP4 to the battery voltage.
5W 100nF
Q1 100 F LK2 1k 220 F
(UN DER 1k IC1 PIC16F88-I/ P Charge current
D2
8.2k
ZD1 BO ARD) 5822 LK3 Maximum charging current is lim- LK1 TP1 TP3 TP +5V ited by the mAh capacity of the cell or 0.22 VR6 500 120 VR1 VR3 – CON2 10 k 10 k battery (as can be seen in Table 1) and
+ REG1 10k ` % LM317 supply. So, if you charge at 2.5A, the TO 10 F BATTERY 220nF R CHARGE NiMH % " " to deliver this current. DC IN TH2 Note that most ‘transformer’ type Fig.3: full-size component overlay – compare this with the photograph of our prototype at right. If the 220μF capacitor you have is higher than 14mm, it of current, while some ‘electronic’ * * 5 % % # mode supply) may be able to.
Outputs RB1 and RB2 of IC1 drive protection for the following capacitor Software the Thermistor and Charge LEDs re- and regulator REG1. ! % % " " spectively via 470Ω resistors. An LM317T is used to provide a the EPE Library site, access via www. regulated 5V supply to IC1 and the epemag.com. Pre-programmed PICs Constant current source trimpots. This was chosen in prefer- will also be available from Magenta Op amp IC2 and MOSFET Q1 are con- ence to a standard 5V regulator because Electronics – see their advert in this nected to provide a controlled current it can be adjusted to supply a precise issue for contact details. source to charge the battery (connected \| | ~ via CON2). Op amp IC2 compares the settings of VR1 to VR5 more accurate. Construction voltage across the 0.22Ω 5W resistor (at The Fast NiMH Charger is con- pin 6) with the DC voltage derived from Voltage requirements structed using a 98mm × 53mm PC the RB3 output of IC1 (at IC2 pin 5). To fully charge a battery you will board, code 720. This board is available The output from RB3 is a 5V 500Hz require up to 1.8V per cell from your from the EPE PCB Service. The printed pulse-width-modulated signal, which circuit board component layout and % terminal voltage shown on the battery wiring is shown in Fig.3. X > Ω ] Ω resistors ] >| Z It is housed in a diecast box meas- and a 10μ ! - ~| " % uring 111mm × 60mm × 30mm. A fan % will need a DC input voltage of 9V (5 # - a DC voltage. × 1.8V). Similarly, an 18V battery will % \\ K ];\ K It is this smoothed DC voltage which have 15 cells and you will need 27V 25.5mm mounts on the case to ensure effectively sets the current level pro- (15 × 1.8V) to charge it fully. that the charger runs reasonably cool. vided by MOSFET Q1 to the battery. However, while the voltage require- ^ " Diode D1 is included to prevent ment for charging one, two or three cells the PC board for any defects, such as the battery from discharging via the is less than 7V, in practice you need " - intrinsic reverse diode inside MOSFET more than 7V at the input to ensure ` [ Q1, when the power is off. D1 is a 3A that the LM317T regulator operates Z ` $ " correctly, ie, remains in regulation. 2-way screw terminals will need to be has less than half the forward voltage You can operate the charger in a car, larger than the 0.9mm holes required of a normal power diode. Typically, in which case the input voltage will be for the other components. it has about 380mV across it (at 2.5A) around 12V with the engine stopped = compared with a standard diode which and up to 14.4V with the engine run- been shaped to clear the internal cor- has 0.84V across it at 2.5A. The lower ning. With 12V in, you can charge up to ner posts of the box and that the 6mm voltage drop also means less power six cells (ie, a 7.2V battery). With 14.4V diameter access semicircle for Q1’s loss in the diode; 0.95W at 2.5A com- (ie, engine running), you can charge screw has been cut from the edge of pared to 2.1W in a standard diode. up to eight cells (ie, a 9.6V battery). the PC board – see Fig.3. + % Note also that using a supply volt- ` > resistor colour code table as a guide to This diode provides reverse polarity required to charge the cells will cause each value, or use a digital multimeter
40 Everyday Practical Electronics, August 2009 Constructional Project
The complete charger, reproduced close to life size. Q1 is mounted under the PC board – you can just see its tab poking out the left side (between the terminal blocks). Inset below is the wiring of the NTC thermistor, which attaches to the side of the box, monitoring temperature rise.
2-WAY HEADER PLUG HEATSHRINK SLEEVES (2) NTC THERMISTOR OVER WIRE CONNECTIONS (TH2)
OUTER HEATSHRINK SLEEVE OVER THERMISTOR, SPADE LUG & CONNECTIONS SPADE LUG to check each resistor before inserting LEDs, while LED3 is a red LED. They up 90° and are soldered to the copper it into the PC board. are ultimately bent over at right angles underside of the board (they just poke Next, install the wire link (top right at a point 10mm above the PC board, through the upper surface, underneath in Fig.3), the diodes, the PIC (IC1) the 0.22Ω 5W resistor). socket and IC2, taking care to orient holes in the side of the charger box. You need to get the MOSFET into the each with the correct polarity. Do not Next, solder the trimpots in place. right position so that when the completed insert IC1 in its socket at this stage. They have different values, so be sure to PC board is placed in the box, a hole can The capacitors can go in next. Note install the correct unit in each position. be drilled through the case and heatsink. that the electrolytic types must be ori- Note that the 10kΩ trimpots may be This is a little tricky to achieve be- ented with the polarity shown. If the marked with 103, the 20kΩ with a 203 cause the centre leg, the drain (D), is 220μF 50V capacitor is higher than the and the 500Ω with a 501 instead of the actually shorter than its gate or source 14mm-high type used, it may need to actual (ohms) value. legs. Bend the drain up 90° 5mm out be mounted on its side (over ZD1 and '] +` from the body of the MOSFET and > % " board with its leads bent over to insert similarly bend the source and gate legs Follow these parts with the 2-way into the appropriate holes. It is secured up 90° 7mm out from the body. and the 3-way headers for the jumper using an M3 screw and nut. Now solder Q1 in position and turn links, then install PC stakes for test Now install the DC socket and 2-way the board over. The hole through Q1’s points TP1-TP5 and for the thermistor screw terminal connectors. At this heatsink should be right in the middle TH2 connection. Also, install the PC point, apart from MOSFET Q1, the PC of the access semicircle cut in the edge stakes for switch S1, TP GND and TP board assembly is complete. of the PC board. +5V test points. The bases of each of the three LEDs Mounting Q1 Boxing it should be 15mm above the surface of Q1, an IRF540 MOSFET, is not actu- Insert the PC board into the diecast the PC board. Orient them with the an- ally mounted on the PC board – it screws box and mark out the corner mounting ode (longer lead) toward the left of the to the case 6mm underneath the board. holes in the base of the box and also PC board. LED1 and LED2 are the green As shown in the photo, its legs are bent the hole position for Q1. Drill these
This close-up shows how Q1’s legs are Here’s how the thermistor (TH2) is The battery temperature thermistor bent up and soldered to the copper ‘heatshrinked’ to a spade lug and then ]` underside of the PC board. secured to the box side. battery holder so it contacts two cells.
Everyday Practical Electronics, August 2009 41 Constructional Project
While you are about it, cut, solder and insulate a similar pair of wires for switch S1. These wires should be roughly 70mm long. One connects to the centre terminal of the switch and it doesn’t matter which terminal the other goes to – if it appears to work ‘upside down’ (ie, off in the down position), you simply turn the switch through 180°. Assembly The heatsink and PC board are screwed to the bottom of the box, which (when completed) is then turned over and becomes the top side. The lid then becomes the base. Before mounting the heatsink, apply a thin smear of heatsink compound to its base. Then attach the heatsink to the box bottom with the M3 × 10mm screws This view shows the mounting positions for the LEDs and switch (front) plus DC and 6.3mm threaded plastic standoffs. socket and thermistor (rear). Next, secure Q1 to the base of the box, along with its silicone insulating out to 3mm in diameter. Now place The end of the box adjacent to Q1’s washer and insulating bush. We used the heatsink squarely onto the base of hole needs a 9.5mm hole for the cable an M3 × 10mm from the inside and a the box and mark out the four corner grommet (our photos in fact show a 6mm M3 tapped spacer on the outside. mounting holes and the Q1 hole onto 12.5mm grommet – because we had one You could use just an M3 nut here, the back of the heatsink. Drill these – but a 9.5mm grommet would be better). but the exposed screw thread does out using a 3mm drill bit. Thermistor TH2 is mounted on a spade not look as neat as the spacer – and Deburr the holes with a larger drill terminal using a 4mm length of heatshrink besides, the spacer is easier to grip bit and in particular, make sure that tubing. This then mounts on the box to when tightening it up! the area around the hole inside the detect heatsink temperature. First, cut The PC board is secured to the nylon box for Q1 to mount on is smooth, so the thermistor leads to 5mm length and spacers using four M3 × 5mm screws. that the insulating washer will not be solder two 50mm lengths of light-duty Before going any further, check to punctured. insulated wire to it. Insulate the joints make sure that the metal tab of Q1 is, Holes need to be drilled in the side of with 1.5mm heatshrink tubing. Now at- in fact, isolated from the metal box. the box, as shown in Fig.5. These holes tach the two free wire ends to the 2-pin With your multimeter on a mid-range are for the three LEDs and power switch header connector. The thermistor can be ohms scale, connect one lead to the on one side and the DC socket and ther- attached to the spade terminal with the box and the other to Q1’s tab (or the mistor TH2 mount on the other side. heatshrink tubing. cathode [striped end] of diode D1). The reading should be above 1MΩ. If it is low ohms, check that the insu- Beware sheep in wolf’s clothing! lating washer and bush are installed correctly and that the washer is not Be careful if you buy NiMH batteries over the ’net – you might not quite punctured. If you get a low reading, get what you expect. correct the problem before proceeding. We’ve seen several warnings about the ratings of rechargeable bat- Attach a suitable card side panel teries coming from suppliers in Hong Kong and China (among other label to the box and bend the LED leads places) and readily available on eBay, for example. over to just protrude through the holes It seems some of Asia’s inscrutable manufacturers or distributors simply in the side of the box. print whatever they think will sell their cells without too much angst. If The previously-prepared thermistor (TH2) attaches to the side of the box that means labelling a 1500mAh cell (which of course is much cheaper with an M3 × 5mm screw and nut. Its to produce), as a 2500mAh, then so be it. wires connect to the PC board as shown. Another source has warned about ‘C’ and ‘D’ cells, which are actually The 70mm-long wires from switch S1 ‘AA’ cells inside a ‘C’ or ‘D’ case. (which sits directly over IC2) connect Even if you do pay a little more to buy your NiMH or NiCad cells from to the appropriate PC stakes and both reputable retailers (and that’s not always the case anyway), you have the switch itself and the PC stakes are the availability of recourse if your purchase isn’t what it appeared to be, insulated with heatshrink tubing. or what you thought it should be. Wire the terminals on the PC board for Try doing that with an email address in, well, where? The old maxim the battery and thermistor (TH1) using applies: if it looks too good to be true, it probably is! medium-duty wire. Use red for battery positive, black for battery negative and
42 Everyday Practical Electronics, August 2009 Constructional Project
Parts List – Fast NiMH Charger
1 PC board, code 720, available 5 M3 × 10mm screws 2 3mm green LEDs (LED1,LED2) from the EPE PCB Service, size 1 M3 × 6mm tapped spacer 1 3mm red LED (LED3) 98 × 53mm 2 M3 nuts 1 16V 1W Zener diode (ZD1) 1 diecast box, 111 × 60 × 30mm 1 6.4mm spade lug, chassis hole 1 1N5822 3A Schottky diode (D1) 1 fan type heatsink, 55 x 105 × mounting 1 1N4004 1A diode (D2) 25.5mm 1 TO-220 silicone insulating 1 mini SPDT toggle switch (S1) washer Capacitors 2 2-way PC-mount screw terminals 1 3mm TO-220 insulating bush 1 220F 50V PC electrolytic 1 PC-mount 2.5mm DC socket 1 battery holder, suit charged cells 1 100F 16V PC electrolytic 1 18-pin IC socket 2 cable ties 2 10F 16V PC electrolytic 5 2-way headers 30mm length of 0.8mm tinned cop- 1 220nF MKT polyester 1 3-way header per wire 2 100nF MKT polyester 3 jumper shunts 120mm lengths of red, black, green 4 PC stakes and yellow 1 2-way jumper connector medium-duty hookup wire Resistors (0.25W, 1%) 2 NTC thermistors (10k @ 25°C) 120mm lengths of red and black 1 10k 3 470 (TH1, TH2) light-duty hookup wire 1 9.1k 1 120 1 4-way (or 6-way) automotive Heatsink compound 1 8.2k 1 47 connector 3 1k 1 0.22 5W 1 9.5mm grommet Semiconductors 4 small adhesive rubber feet 1 PIC16F88-I/P microcontroller, Potentiometers 1 50mm length of 1.5mm diameter programmed with 1 500 horizontal trimpot (code heatshrink tubing NiMHCharger.hex (IC1) 501) (VR6) 1 50mm length of 4mm diameter 1 LM358 dual op amp (IC2) 4 10k horizontal trimpots (code heatshrink tubing 1 IRF540 MOSFET (Q1) 103) (VR1-VR4) 4 6.35mm nylon M3 tapped spacers 1 LM317T adjustable 3-terminal 1 20k horizontal trimpot (code 6 M3 × 5mm screws regulator (REG1) 203) (VR5) yellow and green wires for the ther- (positive to the centre of the plug) and So, for example, with LK1 installed mistor wiring. These pass through the turn on. The power LED should light. and VR1 set so that TP1 is 5V, the cable grommet and into the terminals. Connect a multimeter between TP timeout will be 25 hours. Similarly, if Because we wanted to make the charg- +5V and TP GND and adjust trimpot TP1 is 1.2V, then the timeout will be er adaptable to other batteries, the other VR6 for a reading of 5.0V. Now check six hours (5 × 1.2). ends of the wire connect to an automo- that there is 5V between pin 14 and pin Refer to the ‘NiMH charger settings’ tive connector plug and socket, which 5 of the IC1 socket. If this is correct, section to work out the timer value then connects to the battery holder and switch off power, wait a short time and required. Table 1 at the end of this thermistor. For a permanent connection, then install IC1 into its socket. article also shows typical settings for the connector could be omitted, with the various capacity cells. battery holder/thermistor wires going Adjustments Temperature rise detection (dT/dt) straight to the appropriate places on the Thermistor TH1 setting is adjusted can be adjusted from between 0.5°C battery holder. using VR5, so that the voltage between per minute rise to 5°C per minute rise. Ensure the connections to the ther- TP5 and TP GND is 2.5V when the This is done using VR2 and measuring mistor are sleeved with heatshrink thermistor is at 25°C (ie, if the ambient between TP2 and TP GND. There is a tubing to prevent any shorts to the temperature is 25°C, adjust VR5 so that direct correlation between the voltage battery holder terminals. the voltage between TP5 and TP GND and the setting: a setting of 2.5V at TP2 The thermistor needs to be mounted is 2.5V). If the ambient is 20°C, set it will set the dT/dt value to 2.5°C per in the battery holder so that it contacts for 2.8V or to 2.2V for 30°C. Both the minute rise. Initially, set VR2 so that at least one of the cells under charge. We timeout and dT/dt values are adjusted the voltage at TP2 is 2.5V. drilled a hole in a 4×AA cell holder so using trimpots VR1 and VR2. Test that the thermistor is sandwiched be- points have been included to allow Option tween the cells in the holder (see photo). easy measurement. Installing links LK2 and LK3 enables Depending on the type of battery The timeout can be set from 0 to 25 top-up and trickle charge respectively. holder you use (or none at all) your hours. In its simplest arrangement, the If you want top-up only, install LK2; cells may need to have the thermistor voltage at TP1 gives the timeout in hours. if you want both top-up and trickle mounted with some Velcro or similar For example, if VR1 setting gives 5V charge install LK2 and LK3; if you around the cell body. between TP1 and TP GND, the timeout want trickle without top-up, install LK3 only. Setup time period, then you can install LK1. If any of these two links are se- With IC1 still out of its socket, now This acts as a x5 multiplier so that the lected, you will need to set the trickle connect your plugpack to the DC socket time period is increased. charge rate. The top-up charge is
Everyday Practical Electronics, August 2009 43 Constructional Project
10mm LONG 4 x 5mm LONG M3 MACHINE M3 SCREWS SCREW PC BOARD
INSULATING 4 x 6.35mm BUSH Q1 M3 TAPPED SPACERS SILICONE WASHER
6.35mm LONG M3 TAPPED 4 x 10mm LONG SPACER M3 SCREWS FAN TYPE HEATSINK
Q1 MOUNTING HOLE
HOLE FOR 3.0mm 6.0mm CABLE DIAMETER GROMMET DIAMETER 9.5mm DIAM
10.5 6
LID SIDE 37 LID SIDE 48 CL 59 Q1 MOUNTING HOLE 70
Q1 MOUNTING HOLE 3.0mm DIAMETER
ALL DIMENSIONS IN MILLIMETRES 6.35mm 3.0mm DIAMETER DIAMETER
Fig.4 (top) shows the way the PC board assembly and Q1 are mounted 9.0 in the box, while Fig.5 (above and 8.0 right) gives you all the drilling details LID SIDE 32 for the case. 71
% % ! | J % " " \;; = % - >; = NiMH charger settings " ^ % % ! ]\ " % # % " % = = " ! " % " # = " ]; Ω >\$` " # "
Resistor Colour Codes
o No. Value 4-Band Code (1%) 5-Band Code (1%) o 1 10kW brown black orange brown brown black black red brown o 1 9.1kW white brown red brown white brown black brown brown o 1 8.2kW grey red red brown grey red black brown brown o 3 1kW brown black red brown brown black black brown brown o 3 470W yellow violet brown brown yellow violet black black brown o 1 120W brown red brown brown brown red black black brown o 1 47W yellow violet black brown yellow violet black gold brown
44 Everyday Practical Electronics, August 2009 Constructional Project
Table 1: Typical settings for the Fast NiMH Charger for a range of cell capacities.
Battery or Trickle current Slow charge (15h) Standard charge (5h) Fast charge (1.5h*) cell capacity (LK3 in) (* at or below 2.5A) Top up with LK2 will be (VR1 @ 3V, LK1 in) (VR1 @ 5V, LK1 out) (VR1 @ 1.5V, LK1 out) 4 x trickle setting (Do not select top-up) (Top-up not recommended)
200mAh 10mA 20mA 60mA 200mA (VR3 @ 100mV) (VR4 @ 20mV) (VR4 @ 60mV) (VR4 @ 200mV) 400mAh 20mA 40mA 120mA 400mA (VR3 @ 200mV) (VR4 @ 40mV) (VR4 @ 120mV) (VR4 @ 400mV) 700mAh 35mA 70mA 210mA 700mA (VR3 @ 350mV) (VR4 @ 70mV) (VR4 @ 210mV) (VR4 @ 700mV) 900mAh 45mA 90mA 270mA 900mA (VR3 @ 450mV) (VR4 @ 90mV) (VR4 @ 270mV) (VR4 @ 900mV) 1000mAh 50mA 100mA 300mA 1.0A (VR3 @ 500mV) (VR4 @ 100mV) (VR4 @ 300mV) (VR4 @ 1.0V) 1500mAh 75mA 150mA 450mA 1.5A (VR3 @ 750mV) (VR4 @ 150mV) (VR4 @ 450mV) (VR4 @ 1.5V) 2000mAh 100mA 200mA 600mA 2.0A (VR3 @ 1.0V) (VR4 @ 200mV) (VR4 @ 600mV) (VR4 @ 2.0V) 2400mAh 120mA 240mA 720mA 2.4A (VR3 @ 1.2V) (VR4 @ 240mV) (VR4 @ 720mV) (VR4 @ 2.4V) 2500mAh 125mA 250mA 750mA 2.5A (VR3 @ 1.25V) (VR4 @ 250mV) (VR4 @ 750mV) (VR4 @ 2.5V) 2700mAh 135mA 270mA 810mA 2.5A (1.6h) (VR3 @ 1.35V) (VR4 @ 270mV) (VR4 @ 810mV) (VR4 @ 2.5V) (VR1 @ 1.6V, LK1 out) 3000mAh 150mA 300mA 900mA 2.5A (1.8h) (VR3 @ 1.50V) (VR4 @ 300mV) (VR4 @ 900mV) (VR4 @ 2.5V) (VR1 @ 1.8V, LK1 out) 3300mAh 165mA 330mA) 990mA 2.5A (2h) (VR3 @ 1.65V) (VR4 @ 330mV (VR4 @ 990mV) (VR4 @ 2.5V) (VR1 @ 2.0V, LK1 out) 4000mAh 200mA 400mA 1.2A 2.5A (2.4h) (VR3 @ 2.0mV) (VR4 @ 400mV) (VR4 @ 1.2V) (VR4 @ 2.5V) (VR1 @ 2.4V, LK1 out) 4500mAh 225mA 450mA 1.35A 2.5A (2.7h) (VR3 @ 2.25V) (VR4 @ 450mV) (VR4 @ 1.35V) (VR4 @ 2.5V) (VR1 @ 2.7V, LK1 out) 5000mAh 250mA 500mA 1.5A 2.5A (3h) (VR3 @2.5V) (VR4 @ 500mV) (VR4 @ 1.5V) (VR4 @ 2.5V) (VR1 @ 3.0V, LK1 out) 9000mAh 450mA 900mA 2.5A (5.4h) 2.5A (5.4h) (VR3 @4.5V) (VR4 @ 900mV) (VR4 @ 2.5V) (VR4 @ 2.5V) (VR1 @ 1.08V, LK1 in for x5) (VR1 @ 1.08V, LK1 in [x5]) similar to the charge rate and again LK1 setting. Any changes to other charging period is too short and the top-up is not recommended. settings will be incorporated in the batteries do not deliver power for the charging. expected period. In this case, turn Timeout VR2 further clockwise to increase Timeout should be set to 1.5 times Trickle the dT/dt value. the Ah rating of the battery divided by The trickle charge requirement If the battery pack appears to get hot the charge current. So, a 2500Ah bat- is calculated by dividing the amp after full charge has been reached, turn tery charged at 1A should be charged hour rating of the cells by 20. So, for VR2 back anticlockwise for a lower after 2.5 hours, which means that the example, if the cells are 2400mAh, dT/dt value. EPE timeout is set to 3.75h. This would be then the trickle current should be a 3.75V setting at TP1. 120mA. Any changes to the timeout value When testing, the charger may Reproduced by arrangement when charging will not take effect stop before full charge or it may with SILICON CHIP until power is switched off and on tend to overcharge the batteries. magazine 2009. again. This includes changes to the Under-charge will be evident if the www.siliconchip.com.au
Everyday Practical Electronics, August 2009 45 Recycle It
BY JULIAN EDGAR
F YOU’RE A SAILOR Iit’s a must to know wind speed; and A low-cost large-display % ! - % % " " anemometer " % % Live in a windy area? Like to have a big dial ` % showing the outside wind speed? Here’s an ^ anemometer that you can build for next to nothing. % % % % % Components Z ¡ % " " % " " # # % " = " " |Z$ ! " " " |` % - ! % " " "
UE
Fig.1: the anemometer uses the internals of a discarded mouse to generate a frequency output proportional to wind speed. This signal is fed into an Fig.2: the mouse plug pinouts. You 5 * 5 5 5 circuit made from a handfull of passive components. The resulting voltage other mouse plugs by doing a web is displayed on the speedo. search for ‘mouse pinouts’.
48 Everyday Practical Electronics, August 2009 Recycle It
A video head salvaged from an old VHS VCR provides the bearings, mounts and precision shaft for the anemometer.
" % % a VCR in Recycle It! ; ! |` In this view, you can see (from top to bottom), the stainless steel measuring spoons that form the cups, the upper section of the video head, the shaft, the upper pipe $ cap, the lower section of the video head containing the bearings, the slotted optical " " wheel and sensors, and the mouse circuit board. " " - ! " % % & = - | Recycle It! " ; | ! % # % ! " " - - % The slotted optical sensor wheel is glued to the end of the shaft. The mouse circuit " board is mounted so that the slotted wheel interrupts the light beam between an |` LED and its adjoining sensor – just as it did in the mouse. Only one of the two mouse sensors is used (the unused one can be seen at bottom left). ; ; %# " " Anemometer design " ! $ % % " ! &' %
Everyday Practical Electronics, August 2009 49 Recycle It
Fig.3: this diagram shows how the mouse, cassette player and charge pump are interconnected. Note that only the existing external connections to the cassette player PC board are used – you don’t need to probe into its internal circuitry. The regulated * 5 & 5 * 5 * 5 light beam as it spins. These compo- Building it varied from about 40Hz to 2000Hz. Of nents are used to generate a frequency The key to making the anemometer course, if you have one, a scope is ideal that varies in proportion to wind speed. is to build it in the right sequence of ` The signal from the mouse is then am- steps – that way, you can test each part solder a wire to this signal pin. " of the system as you go along. The output of the sensor is likely to be a varying DC signal. In fact, you into a charge pump circuit that comprises Optical sensor: the mouse is used to don’t even need a frequency meter to just a handful of passive components. provide the optical sensor of the an- check this – just use your trusty old This circuit converts the frequency into emometer. The PC board in the mouse analogue multimeter switched to a low a voltage, which is then read on the car remains intact – we just tap into it to DC voltage range. At low frequency speedo (or VU meter). If you use a speedo, ! % you’ll be able to read the wind speed % or slower, depending on the speed of directly in km/h from the dial. signal output, which is taken directly the wheel. By altering the charge pump ca- from the photosensor. To block this DC component of the pacitors, a variety of meters can be Fig.2 shows the pinouts of the signal, wire a 470nF (0.47μF) capacitor catered for. plugs used on PS2 mice. In this ap- in series with the output – this con- To make it all happen you don’t plication, we need to use only the verts the signal to an AC waveform. need to get deeply into the intricacies power (+5V) supply and ground of the circuits of the mouse, cassette (GND) connections. You now have an optical sensor with deck or speedo – provided you have a Open up the mouse, cut off the cable a high-resolution frequency output! frequency reading meter, it’s all pretty and then use Fig.2 to identify the power Amplifier: the cassette deck is used to straightforward. Fig.1 shows a block and ground leads. Apply 5V to these amplify the small signals coming from diagram of how the anemometer works. leads (the voltage doesn’t have to be the optical sensor. To achieve this, the " signal output from the optical sensor ] \| is connected to the tape head input of Main Features adjustable bench power supply) and the cassette player. then use a frequency measuring meter Access the cable that goes to the to probe the pins of one of the two tape head. In most cheap cassette Large analogue display internal light receptors (positive probe players, this will comprise just a Span can be set to suit local wind of the meter to the device and negative single signal wire inside the shield. conditions to the ground wire). Alternatively, you Connect this signal wire to the signal Works down to very low wind " ` output of the optical sensor, then speeds same signal. connect the shield (braid) of the head Now spin the small slotted wheels input wire to the ground wire of the Linear or non-linear scales by hand and keep probing until you mouse – see Fig.3. Makes use of junked equipment Power up both the cassette player that increases with the speed of one and the mouse, set the cassette player Very cheap to make of the wheels. In the prototype, this volume to full and press the ‘play’
50 Everyday Practical Electronics, August 2009 Recycle It
The mouse circuit board is held in position by a bracket formed from scrap aluminium sheet. Note that heatshrink has been used as an insulator between the board tracks and the bracket.
button. When you spin the optical screwdriver and a small metric Allen The spinning disc has lots of slots in it wheel in the mouse, you should hear key. Some brass collars are also a light – we counted 40, but that might not be a noise from the cassette player’s # " - right! In any case, the output resolution speaker that changes in pitch with moved by gently using a hammer and of the sensor is very good – if you wish, wheel speed (in fact, if all you want is a punch. Prise out the black magnetic you can calibrate the scale to read wind speeds of just a few kilometres per hour. an audible wind speed indicator, you material that is within the head. It eas- can pretty well stop right now – the ily shatters, so be careful when doing % this – it’s best to wear safety glasses when performing this operation. wires from the head (perhaps because Once you’ve got the head bare, you % can build the impeller. We used three touch the different head connections ] >; % % - spoons from a supermarket. These ning. Touching the correct signal wire particular ones were made of stain- will result in a loud hum in the speaker. less steel with a non-slip (and non- If you are using a mains-powered cassette player, you must take great The spoons were bolted together, care that you cannot come into contact with the high voltages. In this case, it is using the existing holes located at best to extend the head wires outside one end of the handles. The spoons of the case and then temporarily close were then spread evenly (ie, with a it up again. ]>;$ ^ were drilled through the spinning Stainless steel measuring spoons were gain, it is susceptible to picking up aluminium housing and the handles used to form the anemometer cups. These noise. To reduce this, a 1kΩ potentio- of the spoons. The spoons were then were bought (gasp!) new for the project. meter is wired across the mouse output, bolted in place using short screws and You need three spoons of the same (15 or 20ml) size. % % - nuts and once this was done, the heads of the spoons were carefully twisted inside of a 90mm PVC pipe cap. As is adjusted so that adequate signal is through 90° to form the anemometer with the rotating part of the head, provided without there being too much cup assembly. some new holes will probably need noise present (indicated by lots of noise The completed assembly should to be drilled through the aluminium in the speaker, even with no rotation of spin freely in even the lightest puff for the mounting bolts. % ! % of wind. If the assembly is out of ! complete circuit of the anemometer – is balance, hold the shaft horizontally mouse wheel to the opposite end of shown in Fig.3. and see which cups always points the shaft to the cups. Cut the slotted downwards. Place a small weight on encoder wheel off its plastic shaft and the side opposite. Getting the assem- bly well-balanced yields dividends side, being careful not to burr the tiny Spinning assembly: disassemble the in longevity – an out-of-balance shaft slots. Then, using instant adhesive, video head, gutting it of any electron- puts a greater load on the bearings. very carefully glue the slotted wheel ics that you see. Pulling the head The half of the video head that to the end of the anemometer shaft. It apart usually requires a Phillips head contains the bearings is bolted to the needs to be perfectly concentric; ie,
Everyday Practical Electronics, August 2009 51 Recycle It
] 5 5 weights – here a bolt and some extra nuts (arrowed) have been placed on one
] * 5 5% 5 5 & & when the shaft is turning there is no Display: the display can comprise an the increments will be found during run-out. electronic car speedo or tachometer, the calibration procedure (see below). The mouse PC board is mounted so or a cassette deck VU meter. You now have a large analogue that the slotted wheel spins between The car instruments make for a anemometer readout! the LED and its adjacent photosensor. much more impressive readout, so Power supplies: two voltages need to We used a small piece of scrap alu- we’ve used one of those. In any case, be provided: 5V to the mouse circuit minium to make the locating bracket. we don’t need the frequency-to- and (usually) 6V to the cassette player Note that if the shaft has a tendency to voltage converter that’s used within (we now know these components as slide downwards through the bearings, these car instruments; instead, as - so causing clearance problems between mentioned earlier, we make our own spectively). the slotted wheel and its sensor, place charge pump system. Doing this If absolute accuracy in the wind a drop of instant glue on the shaft means that we can match the ampli- speed readout isn’t required, the am- right next to a bearing before sliding " % " it through the bearing to the correct very wide range of meters, as well as mains, batteries or a plugpack – what- position. easily changing characteristics like ever was originally used by the cassette You now have a very sensitive and smoothing and range. player. The down-side of this approach durable spinning anemometer head Remove the speedo or tacho and is that the displayed wind speed will with a variable frequency output! strip it down until just the meter and % its electric movement remain. When This is because the square-wave am- a low voltage (eg, 2V) is applied, the A Fun Instrument meter should swing full scale. Take rail – the cassette player is no longer note of the positive and negative leads, " If you want a fun instrument rather than as revealed by this test. The alternative is to use a voltage a calibrated km/h design, simply pick If you’re using a speedo, you should regulator, which is what we chose capacitors in the charge pump that be able to retain the standard km/h to do. As well as providing better give full-scale deflection of the speedo scale. Alternatively, if you use a tacho instrument accuracy, this also al- when the cups are quickly flicked. Then or you want the scaling to be different to lows easy calibration in a car, as the use a computer, scanner and printer to the original on the speedo, a new scale system can be powered from the car make a scale that shows wind speeds will need to be made using a scanner, supply. We powered the regulator like ‘Boring’, ‘Some Excitement’, ‘Hell PC and printer (see Recycle It! in the from a spare plugpack we had previ- It’s Blowing’, ‘Where’s The Cat Gone?’, Nov ’08 issue for more on rescaling car ously salvaged. ‘Take Shelter!’ and ‘Are We Still Alive?’. tachos). In this case, the positions of The supply for the optical sensor is obtained by simply using a 10kΩ pot across the power feed that originally Fig.4: this charge went to the cassette player motor, ad- pump circuit is justed to provide 5V when loaded by used to convert the the optical sensor. ~ 5 Fig.3 shows the power supply wir- " mouse to a DC signal proportional to the optical sensor. wind speed. Frequency-to-Voltage converter: the frequency-to-voltage converter (charge "
52 Everyday Practical Electronics, August 2009 Recycle It
The basic layout: (1) cassette player circuit board, being pot that provides the 5V ➊ (3) voltage regulator and associated capacitors * ~ * be major mains supply ➎ 0 input attenuating pot and ➋ 5 5 < 5 5 5 5 & expensive looking NEC pots * 5 ➌ ➍
and is best optimised on the bench `> " It all starts to sound a bit compli- with the whole system working. until the needle moves smoothly. cated, but when you realise that the Fig.4 shows the way in which the `] " - frequency-to-voltage charge pump cir- charge pump works. For the moment, low it to fully discharge during the cuit uses only six low-cost components, | ] `] time that the input signal is low. In the you can breathe easily again! `> prototype, where the car speedometer ! " `] `> `] ];;Ω `] initially lash up the anemometer circuit ] `> ^ `] % ];μF electrolytic capacitors (wired on the bench – power supplies and all. `> J negative to negative to make the pair Start with the capacitor values cited `] `> # % `> " | ] % %- >>;μ ! ]~Ω resistor in series with is as low as possible. Spin the anemom- Z % `> `] eter cups by hand – rotating them fairly has received a small charge increase. slowly – and check that the speedo (or % Note that if you are using a VU meter | `] > " `> `] `> little. " ] " % `] % " Now spin the cups faster and check the discharge path. The result is that much lower in value. = each time the input voltage goes high, a small amount of charge is added to `> `> proportion with the input frequency. ` `> % ¡ `> is being constantly discharged by the | ] % - `> ` `> " % " " " provide a damped meter movement at the lowest frequency output at which % % % turned at the slowest speed at which ] 5 5 * you will be making measurements (this 5 * value depends on the scale you have * 5
Everyday Practical Electronics, August 2009 53 Recycle It
% % + " % % % ! " - " % " % >\ # " Calibration ` " " - % " " The working anemometer, seen positioned high on the roof. The cup covering ¢ the centre section of the rotating assembly was made from an aerosol cap. For " ! improved durability, everything you see here should be painted. " % " " | ] +|` - - = % " " % | ] " `] " " " # # % # # `] % " % `> % " % " % " % ]; % % `] % % `> % ! % % % " % " ! " ] ]; % % " % # % % % " ! +` " % % " _; Z %- % % % % \; [ % % % % % % `] % % % [ Final assembly Conclusion ! " +` " % " ! " ; " " # - Rat It Before You Chuck It! % ! - % % Whenever you throw away an old TV (or easily be salvaged from goods commonly > J VCR or washing machine or dishwasher being thrown away, we’d love to hear from or printer) do you always think that surely you. Perhaps you use the pressure switch % " there must be some good salvageable from a washing machine to control a pump. % components inside? Well, this column is Or maybe you have a use for the high- % for you! (And it’s also for people without a quality bearings from VCR heads. Or perhaps ^ lot of dough.) Each month we’ll use bits and you’ve found how the guts of a cassette player % % pieces sourced from discards, sometimes in can be easily turned into a metal detector. % EPE mini-projects and other times as an ideas (Well, we made the last one up but you get " smorgasbord. the idea . . .) % $ & `7 `Z + And you can contribute as well. If you If you have some practical ideas, write in [ >;; have a use for specific parts which can and tell us! %%%
54 Everyday Practical Electronics, August 2009 Breadboarding
Breadboarding Projects
by Dr Malcolm Plant
A beginner’s guide to simple, solder-free circuit prototyping Part 11: Festive Lights Project 19: could be incorporated in a festive pulses at a frequency determined by display such as a small cardboard resistors R1 and R2, and polyester shape representing a tree, animal capacitor C1. The output pulses Festive Lights or such like. from pin 3 of IC1 are coupled di- Circuit diagram rectly to the clock terminal, pin SING a few components you 10, of IC2, a 4040 CMOS frequency can easily assemble a light The circuit is shown in Fig.11.1 counter/divider integrated circuit, U display that switches on and can be regarded as comprising which is the second building block. and off at different repetition rates two main building blocks. The first IC2 being a binary divider means that 18 light emitting diodes (LEDs) ar- of these uses a 555 timer, IC1, op- the input frequency is divided by fac- ranged in groups. This performance erating as an astable that generates tors of 2, 4, 8, 16 etc, and these divided
Fig. 11.1. Complete circuit diagram for the Festive Lights project
56 Everyday Practical Electronics, August 2009 Breadboarding
frequencies are available at the output pins to drive the LEDs, which are ar- Components needed... ranged in three banks. Each bank com- Festive Lights prises six LEDs, three of which are on Integrated circuit, IC1: type 555 timer at any moment while the other three are Integrated circuit, IC2: type 4040 CMOS frequency counter/divider and off. In this case, the pins used are Light emitting diodes, LED1 to LED 18: Suggest nine green, nine red, 3(÷32), 2(÷64) and 4(÷128) so that each or colours to choice " &' Capacitor, C1: value 100nF (0.1F) polyester frequency. Resistors, R1, R2: value 100k . Both 0.25W 5% carbon film Flash rate Switch, S1 (On/Off): single-pole, single-throw (SPST) ! J Battery, B1: 9V plus connecting leads at frequency fo, those connected to pin Protobloc and wire links > o/2, while those connected to _ o/4. If the astable frequen- cy is 48Hz, the frequencies at these pins hand-held oscilloscope and found are about 1.5Hz, 0.75Hz and 0.375Hz. to be close to 50Hz as indicated by Given the component values in the the two markers on the rectangular circuit, i.e. R1 = R2 = 100k and C1 waveform pattern. The two markers = 100nF or 0.1F, the frequency of the indicate the period of the waveform astable is given by 1/(0.7(2 × R2 + R1) × as 21ms giving a frequency of 1/21ms C1). Therefore, the frequency is 1/(0.7 × = 1000/21 = 47.6Hz. 300k × 0.1F) = 1/0.7(3 × 105 × 10-7) Notes Component Info ɀ The LEDS do not require series resistors, provided each half bank IC1, type 555 timer IC comprises no less than three LEDs and the supply voltage does not Viewed from the exceed 9V top, an indented dot Fig. 11.2. Waveform produced by the ɀ None of the component values and a ‘half-moon’ astable are critical and it is worth experi- shape at one end = 1/0.7 × 3 × 10-2) = 10/0.21 = 50Hz ap- menting with resistors R1, R2 and indicate pin one. proximately. This is close to the assumed capacitor values. The pins are num- _XZ[ " ! ɀ Other outputs of IC2 can be se- bered anti-clock- PIN 1 frequency of the LEDs attached to pin lected to provide different division wise ending at pin 8 3 of IC2 is thus about 1.5 per second. frequencies and hence different opposite pin 1. As Fig.11.2 shows, the frequency flashing frequencies. The relevant of the astable was checked with a pins are 5, 6 and 7. EPE IC2, type 4040 frequency counter/ divider
PIN 1 7 ] " pins are numbered 1 to 16 going anticlockwise.
LED1 to LED 18, 3mm green (9) and red (9) light-emitting diodes
The longer lead is the anode, the shorter lead is the cathode. Fig. 11.3. Protobloc assembly and wiring details for the Festive Lights circuit
Everyday Practical Electronics, August 2009 57 ELECTRONICS MANUALS ON CD-ROM £29.95 EACH
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Everything you need to know to get started in The essential referencee wworkorkk repairing electronic equipment for everyone studying elelectronicsectronics Around 900 pages Fundamental principles Troubleshooting Over 800 pages In-depth theory Projects to build techniques Servicing techniques Choosing and using test Detailed assembly instructions 1 Full components equipment Reference data Manufacturers’ web links Easy-to- checklists Extensive data tables Manufacturers’ use Adobe Acrobat format Clear and simple layout Vital safety web links Easy-to-use Adobe Acrobat format Clear precautions Professionally written Supplements and simple layout Comprehensive subject range Professionally written Supplements SAFETY: Safety Regulations, Electrical Safety and First Aid. UNDERPINNING KNOWLEDGE: Electrical and Electronic BASIC PRINCIPLES: Electronic Components and their Principles, Active and Passive Components, Circuit Diagrams, Characteristics; Circuits Using Passive Components; Circuit Measurements, Radio, Computers, Valves and manufacturers’ Power Supplies; The Amateur Electronics Workshop; Data, etc. PRACTICAL SKILLS: Learn how to identify Electronic The Uses of Semiconductors; Digital Electronics; Components, Avoid Static Hazards, Carry Out Soldering and Wiring, Operational Amplifiers; Introduction to Physics, Remove and Replace Components. TEST EQUIPMENT: How to including practical experiments; Semiconductors and Choose and Use Test Equipment, Assemble a Toolkit, Set Up a Digital Instruments. Workshop, and Get the Most from Your Multimeter and Oscilloscope, CIRCUITS TO BUILD: The Base Manual describes 12 etc. SERVICING TECHNIQUES: The Manual includes vital guidelines projects including a Theremin and a Simple TENS Unit. on how to Service Audio Amplifiers. The Supplements include similar ESSENTIAL DATA: Extensive tables on diodes, guidelines for Radio Receivers, TV Receivers, Cassette Recorders, transistors, thyristors and triacs, digital and linear i.c.s. Video Recorders, Personal Computers, etc. TECHNICAL NOTES: EXTENSIVE GLOSSARY: Should you come across Commencing with the IBM PC, this section and the Supplements deal a technical word, phrase or abbreviation you’re not with a very wide range of specific types of equipment – radios, TVs, familiar with, simply look up the glossary and you’ll find cassette recorders, amplifiers, video recorders etc. REFERENCE a comprehensive definition in plain English. DATA: Diodes, Small-Signal Transistors, Power Transistors, Thyristors, The Manual also covers Safety and provides web links Triacs and Field Effect Transistors. Supplements include Operational to component and equipment Manufacturers and Amplifiers, Logic Circuits, optoelectronic Devices, etc. Suppliers. Full contents list available online at: www.epemag.com
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Everyday Practical Electronics, August 2009 59 By Robert Penfold
CALCULATED CONNECTION his series is not primarily aimed at Right lines A bit clever beginners, and it is generally written The second way of using a port does not The standard way of reading one bit of a Ton the assumption that the reader use the lines together to transfer values, but port is to use so-called ‘bitwise’ operations, understands the basics of computer interfacing. instead has each one providing a separate and in this context it is the bitwise AND However, we do, occasionally, consider some function. In some cases, these lines are of the operation that is of use. When you look at fundamental aspects of computer interfacing, handshake variety, which simply means that the result of a bitwise AND operation, with and will do so in this month’s Interface article. they are used to control the flow of data into the figures in decimal form, it tends to look Most PC add-ons communicate with the and (or) out of the computer via another port. nonsensical. You really have to look at the outside world via 8-bit parallel ports. Even In other instances they are not used in a figures in their binary versions in order to when using some form of serial port of the supporting role, but are providing the main make sense of things. computer, such as a RS232C or USB type, there will be a conversion to parallel data in the add-on device and communication with the outside world will ultimately be in parallel form. Hidden values There are two fundamentally different ways of using an 8-bit port, and with one method the port is used to read a numeric value from a peripheral, or to write a numeric value to it. As a couple of examples, with a computer controlled power supply you would perhaps write values from 0 to 255 to the peripheral, producing output voltages from 0 to 25.5V with 0.1V resolution. A temperature interface could provide values from 0 to 255, representing a temperature range of 0 to 127.5 degrees Celsius, with 0.5 degree resolution. Fig.1. Demonstration program in action In both cases, the hardware could be relatively complex, but the software is function. For example, they could be used A bitwise AND operation takes each usually very straightforward. The data is sent to control electric motors or lights via relay bit of the first number and pairs it with the or received in binary form on eight digital drivers, or to monitor sensors in an alarm corresponding bits of the second number. lines, but the computing language provides system. There is only a 1 in a bit of the answer the binary-to-decimal or decimal-to-binary In both cases, the lines have individual if that bit is 1 in the first number and the conversions. functions and are not working together to second number. A 1 and a 0 or two 0s result It is usually necessary for the program to transfer numeric data or strings, but the in 0 being placed in the corresponding bit provide some simple mathematics in order to programming language will not necessarily of the answer. The AND operator provides get the scaling right, but there is no need for have the ability to handle the lines on an essentially the same function as a set of eight the programmer to have an understanding of individual basis. Instead, all the output lines 2-input AND gates. binary arithmetic. Everything is handled in must be set at the desired states by writing The program in Listing 1 demonstrates decimal form, and the binary origins of the the appropriate value to the output port. This the use of bitwise ANDing. This has three data are hidden from the programmer. complicates matters if it is only necessary textboxes that are used to enter the two With some types of interfacing, it is to change the state of one line, because numbers to be processed, and to display the actually strings of characters that are handled care has to be taken to leave all the others answer. There are three labels that are used by the computer program, albeit with some at their original states. Reading one line is to display the binary equivalents of the three mathematics provided by a microcontroller in not possible, but the state of an individual decimal values. A button is operated when the interface. Again, the application program line can be determined by reading the value new values are ready for processing. Fig.1 is unlikely to involve even the slightest hint from the port and using some mathematics shows the program in action, with decimal of binary arithmetic. to effectively eliminate the lines that are of values of 15 and 85 being bitwise ANDed to An 8-bit port can only handle a range of no interest. produce an answer of 5. The decimal figures 256 values from 0 to 255, but a wider range It is worth pointing out that micro- seem to lack reason, but matters are clearer of values can be accommodated using a 16- controllers are generally designed to be when the binary values are considered. It is bit port, or two 8-bit types used together to able to handle things on a more bit-by-bit only bits 0 and 2 that are set at 1 in both the provide 16-bit transfers. This gives a range basis when necessary, and may well have values, and so it is only these bits that are set of 65536 values from 0 to 65535, which is instructions that apply to specific lines of a to 1 in the answer. These represent 1 and 4 more than enough for the vast majority of port. Consequently, with a PC add-on based respectively in decimal, giving a total of 5. real-world applications. on a microcontroller it might be possible When combining two 8-bit values to to handle some line reading and writing Masking produce the full 16-bit type, it is still in the microcontroller without recourse to The way in which bitwise ANDing is unnecessary to get involved with binary the PC. This will not always be a practical used to mask bits that are not of interest is values or arithmetic. It is just a matter of proposition though, and some applications very simple. Suppose that it is only bit 7 multiplying the most significant byte by 256 will require the PC to be in full control of the that is of interest. This bit is set at one in the and adding it to the least significant byte. add-on gadget. masking number, but all the other bits are set
60 Everyday Practical Electronics, August 2009 to zero. In decimal terms this means using a if bit 7 of the port is also at 1. In other words, applications it might be necessary to read masking value of 128. Bitwise ANDing the a value of 0 is obtained if bit 7 of the port is at a few bits. This can be achieved by reading value read from a port with a masking value logic 0, and a value of 128 is produced if bit 7 the relevant bits individually, or by using a of 128 ensures that bits 0 to 6 are set at 0 in of the port is at logic 1. Only these two values masking number that enables them to be read the answer, since they cannot be at 1 in both can be produced, and the states of the other as a group. For example, suppose that bits the numbers being processed. The same is seven lines of the port are irrelevant. 0 to 3 are of interest, and bits 4 to 7 must not true of bit 7, which is at 1 in the masking It has been assumed here that only be masked. Using a masking value of 15 number, and will also be set at 1 in the answer one input line will be read, but in some (00001111 in binary) excludes bits 4 to 7, and reads the value present on bits 0 to 3. In the demonstration program, a series Listing 1 of bitwise AND instructions are used to determine the state of each bit in the three Public Class Form1 values, so that their binary equivalents can be printed in the three label components. In a real-world situation the program would Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As often poll the input line, and use a conditional System.EventArgs) Handles Button1.Click instruction to perform a certain task when the TextBox3.Text = TextBox1.Text And TextBox2.Text line goes to the appropriate state. Dim B0, B1, B2, B3, B4, B5, B6, B7 As Byte Sometimes, an input line must be used Dim D0, D1, D2, D3, D4, D5, D6, D7 As Byte to control an on-screen indicator light, and Dim F0, F1, F2, F3, F4, F5, F6, F7 As Byte this facility is included in the demonstration program. The answer of the bitwise AND B0 = (TextBox1.Text And 1) operation is displayed on a set of eight ‘lights’, If (TextBox1.Text And 2) = 2 Then B1 = 1 which go red for logic 0 or green for logic 1. If (TextBox1.Text And 4) = 4 Then B2 = 1 The Line and Shape objects are not a If (TextBox1.Text And 8) = 8 Then B3 = 1 standard part of Visual BASIC 2008 Express If (TextBox1.Text And 16) = 16 Then B4 = 1 Edition, but they can be added via the If (TextBox1.Text And 32) = 32 Then B5 = 1 optional Power Pack download. The latter If (TextBox1.Text And 64) = 64 Then B6 = 1 should be considered essential if you need If (TextBox1.Text And 128) = 128 Then B7 = 1 to produce virtual indicator lights, meters, Label1.Text = B7 & B6 & B5 & B4 & B3 & B2 & B1 & B0 control knobs, or whatever.
D0 = (TextBox2.Text And 1) Write lines If (TextBox2.Text And 2) = 2 Then D1 = 1 In order to write to a single line of an output If (TextBox2.Text And 4) = 4 Then D2 = 1 port, without altering the states of the other If (TextBox2.Text And 8) = 8 Then D3 = 1 lines, it is essential to know the current states of the other lines. Since it is not normally If (TextBox2.Text And 16) = 16 Then D4 = 1 possible to read the current levels from an If (TextBox2.Text And 32) = 32 Then D5 = 1 output port, this must be achieved by using a If (TextBox2.Text And 64) = 64 Then D6 = 1 variable to store the last value written to the If (TextBox2.Text And 128) = 128 Then D7 = 1 port. This value can then be bitwise ANDed Label2.Text = D7 & D6 & D5 & D4 & D3 & D2 & D1 & D0 with a masking number that operates in the opposite way to a masking number used to F0 = (TextBox3.Text And 1) read a single line. If (TextBox3.Text And 2) = 2 Then F1 = 1 The masking value has all the bits set to 1, If (TextBox3.Text And 4) = 4 Then F2 = 1 apart from the bit that is to be changed. For If (TextBox3.Text And 8) = 8 Then F3 = 1 example, if bit 2 is to be changed, a masking If (TextBox3.Text And 16) = 16 Then F4 = 1 value of 251 (255 – 4, or 11111011 in binary) If (TextBox3.Text And 32) = 32 Then F5 = 1 would be used. If bit 2 is to be set at 0, the If (TextBox3.Text And 64) = 64 Then F6 = 1 value obtained from this operation would be If (TextBox3.Text And 128) = 128 Then F7 = 1 written to the port. It is just a matter of adding Label3.Text = F7 & F6 & F5 & F4 & F3 & F2 & F1 & F0 4 to the value before writing it to the port if bit 2 must be set at 1. There are other ways of If F7 = 1 Then OvalShape1.FillColor = Color.Green Else OvalShape1. achieving the same thing, such as a method FillColor = Color.Red that uses the exclusive OR (XOR) bitwise If F6 = 1 Then OvalShape2.FillColor = Color.Green Else OvalShape2. operator, but they are really just variations on the same basic method. FillColor = Color.Red If F5 = 1 Then OvalShape3.FillColor = Color.Green Else OvalShape3. FillColor = Color.Red TO ADVERTISE IN If F4 = 1 Then OvalShape4.FillColor = Color.Green Else OvalShape4. FillColor = Color.Red EVERYDAY If F3 = 1 Then OvalShape5.FillColor = Color.Green Else OvalShape5. FillColor = Color.Red PRACTICAL If F2 = 1 Then OvalShape6.FillColor = Color.Green Else OvalShape6. FillColor = Color.Red ELECTRONICS If F1 = 1 Then OvalShape7.FillColor = Color.Green Else OvalShape7. FillColor = Color.Red PLEASE CONTACT If F0 = 1 Then OvalShape8.FillColor = Color.Green Else OvalShape8. FillColor = Color.Red Stewart Kearn on End Sub 01202 873872 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As or email System.EventArgs) Handles MyBase.Load stewart.kearn@ End Sub End Class wimborne.co.uk
Everyday Practical Electronics, August 2009 61 Readers’ Circuits
Our regular round-up of readers’ own circuits WIN A PICO PC-BASED OSCILLOSCOPE WORTH £799 # # #!" # ##$ % & $% ' ' ( % ) * )+( ( & We pay between £10 and £50 for all material published, depending on %' ( $# ,) * ( ) -. length and technical merit. We’re looking for novel applications and circuit % ( $# ( & $ ) /0 designs, not simply mechanical, electrical or software ideas. Ideas must R !/33 ( & be the reader’s own work and must not have been published or submitted for publication elsewhere. The circuits shown have NOT been proven by us. Ingenuity Unlimited is open to ALL abilities, but items for consideration in this column should be typed or word-processed, with a brief circuit description (between 100 and 500 words maximum) and include a full circuit diagram showing all component values. Please draw all circuit schematics as clearly as possible. Send your circuit ideas to: Ingenuity Unlimited, Wimborne Publishing Ltd., Sequoia House, 398a Ringwood Road, Ferndown, Dorset BH22 9AU. Email: [email protected]. Your ideas could earn you some cash and a prize !
Optical Motion Detector – Ronchigrated he main problem with an optical that the motion detector circuit (Fig.1) can be of the area of the grating, but apart from that motion detector is that it has to be simplified greatly by operating only with one they can be printed in a wide variety of shapes. T equally sensitive to dark targets on a polarity of signal, although in practice it is The grating I made has lines and spaces bright background or to bright targets on a always easier to detect bright-up signals. 5mm wide, positioned 50mm from the pho- dark background. This detector incorporates totransistor (TR6). Spacing depends on the a homemade Ronchi grating which causes Ronchi grating size of target you want to detect and is cal- any target (bright or dark) to produce equal Ronchi gratings are simple patterns of dark culated (by similar-triangles) to be about numbers of ‘bright-up’ or ‘dark-up’ pulses as lines printed on a transparent material. The as wide as the target when projected out it moves across the field of view. This means lines must always be arranged to cover 50% to target range. My 5mm grating would be
+V
e + b C1* R1* TR1 10µ 4M7 BC213L e c R2* b TR2 1k +5V BC213L c TR3 BC213L e b + k R4 C2 D1* 1k TR4 10µ 1N4148 RONCHI GRATING FOR RONCHI GRATING FOR c BC108C a c DETECTING HORIZONTAL DETECTING HORIZONTAL MOTION OR VERTICAL MOTION b TR5 BC108C e c ILLUMINATION b LOGIC CIRCUIT
TR6 e SFH300-3 c R3** PHOTOTRANSISTOR (TR6) 3k9 PHOTOTRANSISTOR *SEE TEXT e VR1** **MAY NEED TO SELECT 10k RONCHI GRATING
0V GEOMETRY OF MOTION DETECTOR
Fig.1. Circuit diagram for the Optical Motion Detector
62 Everyday Practical Electronics, August 2009 suitable for a man-target at about 5m range, (TR6). Because of capacitor C1 and resis- The detector is powered by current stolen though in practice the range isn’t critical. tor R1, it becomes a constant current supply from a logic pull-up, but it can also be run There are lots of ways to make the grating, when the phototransistor current increases from a separate supply, eg 9V, by remov- and it doesn’t have to be a great work of art rapidly. This means that current changes go ing diode D1. The 1k resistor, R2, is there to be effective, as long as the edges are fairly entirely to the base (b) of TR3. This stage to prevent the circuit from ‘crowbarring’ the sharp. I made the lines using black electri- also works as an adaptive threshold, so the supply if too much light accidentally enters cal tape, but they could be computer-drawn detector ignores the mains ripple which rides the enclosure. and printed on transparent film. The ultimate on artificial light sources. This detector doesn’t include a monostable form of Ronchi would be to paint broad black The second stage is a Darlington arrange- like many circuits do. It is assumed that the and white ‘zebra’ stripes on a wall where an ment for TR3 and TR4 to drive the TR5 open- downstream logic will sort out multiple de- intruder has to pass, but putting the stripes collector output stage. This is intended to in- tections. It takes about one second to recover inside the detector enclosure is simpler. terface with logic circuits. Preset VR1 sets the from a detection. You can experiment with the Fig.1 shows some examples of gratings. It sensitivity once the detector is installed. VR1 values of C1 and R1 to adjust the sensitivity to also includes the optical layout of the detector, is adjusted to set the base of TR5 to 300mV target speed and the recovery time. which is basically just a phototransistor (TR6) to 350mV to give good sensitivity without too ‘staring’ through the grating at the outside many false alarms under ambient conditions. Walter Gray, Farnborough world. It needs a good light-tight enclosure, and to be electrically screened, as the detector has a lot of gain. The inside should be painted matt-black and it will also need suitable light- baffles and a hood to prevent unwanted light from hitting the phototransistor. INGENUITY IU is your forum, where you can offer other readers the Circuit description UNLIMITED benefit of your Ingenuity. The Optical Motion Detector circuit Share those ideas, earn some (Fig.1) consists of two stages. The first BE INTERACTIVE cash and possibly a prize. stage, based around TR1 and TR2, supplies a constant voltage to the phototransistor Why not take a look at our website: www.epemag.com
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EverydayE d PracticalP ti l Electronics, El t i AugustA t 2009 63 Circuit Surgery
Regular Clinic by Ian Bell
Filters circuits Part 2
Last month, in response to a question about One of Nuhertz’s main products is Filter help system also provides information on filters on the EPE Chatzone (chatzones. Solutions, an advanced filter design software each filter type, including details of any co.uk) from Paul Goodson we discussed application. They also provide a lower cost type-specific settings. some of the basic concepts behind filter ‘light’ version and, most importantly for Filter attributes: Set order, cut-off circuits. Filters are circuits that pass signals hobbyist and student designers, a free version frequency and various additional options at certain frequencies (in the pass band) while called Filter Free. Filter Free can be downloaded depending on filter type. Filter Free is rejecting signals at other frequencies (in the from www.nuhertz.com/download.html. limited to a maximum of third order filters. stop band). A frequency that divides the pass There are, of course, filter synthesis band from the stop band is a cut-off frequency. applications that are worth checking out. One Implementation: Select one of passive We described various terms and example is FilterPro from Texas Instruments lumped, passive distributed, active, switched characteristics related to filters, such as pass (see focus.ti.com/docs/toolsw/folders/print/ capacitor or digital filter. Choose Active for band, stop band, cut-off frequency, roll-off, filterpro.html). This provides more user the op amp-based analogue filters which we ripple, rise-time and overshoot, and poles control over component values and can are discussing here. and zeros. This month we will be making synthesise higher order filters than Filter Filter class: High-pass, low-pass etc. use of these terms to describe the various Free, but it is restricted to low-pass filters Choose the form of filter you want. filter types which are available. and supports fewer filter types and circuit Freq scale: Controls scale format on As Paul hinted in his question, full analysis configurations than Filter Free. frequency response graphs. Set to Hz and of filter circuits requires some advanced Taking a look at the screen shot of log for a standard frequency response graph mathematics; however, it is possible to Filter Free (Fig.2) you will see various using a Hertz frequency scale. design good filter circuits without doing a sections of the window. A brief outline of Graph limits: Controls range over which vast amount of algebra. Indeed, traditionally, these is given below. Other filter synthesis frequency response graph and time response many filters were designed using a ‘cookbook’ software will require similar data input. waveforms are plotted. A good starting point approach in which tables of values and Filter type: The mathematical function simple formula could be applied to find the for Min Freq and Max Freq is one tenth and on which the filter is based. We will discuss ) respectively. required component values. These days it ten times the cut-off frequency (fC this in more detail shortly. The Filter Free is even easier, with software applications A suggested start point for these times are Min Time available that calculate the component values GAIN / dB FREQUENCY RESPONSE CURVE for you. We will look at an example of such = 0 and Max Time = 10/ software this month. fC. These can easily be 0 Your application should define your ALLOWABLE adjusted if the graphs are PASS BAND not as required. basic filter response (high-pass, low-pass RIPPLE etc) cut-off frequency, required attenuation Ideal filter response: in the stop band, sharpness of cut-off This section has four and allowable pass band ripple. These buttons which display specifications can be visualised using a the corresponding diagram like the one shown in Fig.1. The MINIMUM information when the filter’s frequency response curve has to fit STOP BAND button is clicked. In into the unshaded region in order to meet ATENUATION Filter Free these are the specification. idealised plots based on The major design decisions are what CUT-OFF FREQUENCY / Hz the mathematic functions filter type to use, and what circuit to FREQUENCY (LOG SCALE) PASS BAND STOP BAND and are not based on a implement it with. For each type of filter simulation of the circuit there may be further options or variations implementation. to choose. Similarly, with each basic Fig.1. Visualising a filter specification (low-pass filter) circuit type there may be further choices to make. When using filter synthesis software these decisions will be reflected in the information you have to provide to the software. Filter software The free filter synthesis programme we use in this article is from NuhertzTechnologies (www.nuhertz.com) of Phoenix, Arizona. They were founded in 1999 and describe themselves as a worldwide leader in low and high frequency filter synthesis and analysis. They have developed numerous advanced filter synthesis algorithms to provide design automation of frequency selective circuits. Fig.2. Screen shot of Filter Free
64 Everyday Practical Electronics, August 2009 Active implementation: Determines Butterworth filters this ripple. Increasing the magnitude of the which circuit configuration is used by The Butterworth filter provides the flattest ripple makes the cut-off sharper. Chebyshev Filter Free to synthesise the filter. We will possible pass band, but does not roll off filters show more ringing in response to discuss this in more detail later. Note that as fast as other types, such as Chebyshev input pulses than Butterworth and Bessel some implementations may not be available filters. Gain in the stop band rolls off filters. for some types of filter. The Filter Free steadily towards zero (minus infinity in dB). The gain of the less common type-II help system provides details on the filter The time response to a pulse shows some Chebyshev filters is flat in the pass band, implementations. ringing. The frequency response of a 1kHz but has ripple in the stop band. These filters Circuit parameters: Set circuit-specific third-order low-pass Butterworth filter is do not have as sharp a cut-off as type-I parameters. These also depend on the type shown in Fig.3. Chebyshev filters. When designing a type- and class of filter selected. Refer to the Filter II Chebyshev filter you need to know how Free help system for full details. Clicking Bessel filters much attenuation you need in the stop the Synthesis Filter button provides you Bessel filters have a soft cut-off, but have band as, unlike the other filters described with a schematic of your filter and access to a delay which varies very little across the here, the attenuation does not increase a SPICE netlist. pass band. This means that waveforms continuously as you move away from the As you can see from the screen shot of in-band signals suffer little distortion cut-off frequency. (Fig.2) Filter Free provides eleven different passing through the filter. The Butterworth In Fig.5 is shown the response of a third- types, but we will limit our discussion filter gain in the stop band rolls off steadily order 1.0kHz type-I Chebyshev filter with this month to just three of these: Bessel, towards zero (minus infinity in dB). The 3dB ripples, and Fig.6 shows a third-order Butterworth and Chebyshev, which are frequency response of a 1kHz third-order 1.0kHz type-II Chebyshev filter designed possibly the most commonly used filter low pass Bessel filter is shown in Fig.4. to have a –30dB stop band attenuation. types. Some filter design software may be The flat gain (linear phase) response is The cut-off frequency for Butterworth limited to just one or two types. important in some applications, such as high and Bessel filters is –3dB below the gain The names of filter types typically quality audio. In the time domain, pulses depth in the pass band. This is the standard come from the underlying mathematical applied to a Bessel filter show very little –3dB (half power) point often used to functions on which they are based, overshoot and ringing. In cases where low define bandwidth. However, for type-I these in turn are typically named after signal distortion is needed, using a higher Chebyshev filters the ripple amplitude is the mathematicians who discovered order (more components and complexity) often used to define the cut-off frequency. or developed the theory behind those Bessel filter to get the required cut-off So for a –1dB ripple with Chebyshev functions. For example, Bessel filters are sharpness may be preferable to a simpler filters the cut-off would be 1dB below the named after the German mathematician Butterworth filter. maximum gain in the pass band. This is Friedrich Wilhelm Bessel (1784–1846) the definition used by Filter Free. Note and Chebyshev filters are named after Chebyshev filters that some filter design recipes or software Russian mathematician Pafnuty Lvovich Chebyshev filters have relatively may assume –3dB. Filter design software Chebyshev (1821–1894). Incidentally, steep roll-off at the cut-off frequency in may let you redefine the cut-off point there are many ways of spelling comparison with Butterworth and Bessel from whatever the default is. In Filter Free (transliterating from Russian) the name filters. The gain of type-I Chebyshev filters untick the Standard Pass Band Atten box Chebyshev, so do not be surprised if you varies in the pass band, and they are often if you need a non-standard definition of see it spelt differently! referred to in terms of the magnitude of cut-off frequency.
Fig.3. Butterworth third-order low-pass filter response Fig.4. Bessel third-order low-pass filter response (output from Filter Free) (output from Filter Free)
Fig.5. Type-I Chebyshev third-order low-pass filter response Fig.6. Type-II Chebyshev third-order low-pass filter response (output from Filter Free) (output from Filter Free)
Everyday Practical Electronics, August 2009 65 R3 R4
N N R1 R2 1 OUTPUT R1 R2 1 OUTPUT INPUT INPUT
C1 C2 C1 C2
Fig.7. Second order Sallen and Key low-pass filter Fig.8. Second order Sallen and Key low-pass filter, unity gain version
N C1 C2 1 OUTPUT INPUT
R1 R2
Fig.9. Second order Sallen and Key high-pass filter, unity gain version Other considerations implementation may Fig.10. Filter synthesised by Filter Free. This has the Another major filter design decision take the filter out of frequency response shown in Fig.5 is which circuit is used to implement specification. The type it. Filter Free provides up to nine filter of filter also has an impact on sensitivity. For The high pass version of the Sallen and Key implementation choices. The circuits vary example Chebyshev filters are more sensitive filter is very similar, with the resistors and in terms of the number of components they to component variation than Butterworth capacitors swapped round as shown in Fig.9. require, with the number of op amps and filters. For third-order filters an op amp-buffered capacitors usually being of key concern. In this article we restrict our discussion RC filter is put in front of a second-order Another important issue, particularly with to the Pos SAB option, which is short for Sallen and Key stage. An example circuit higher order filters, is the sensitivity of the filter Positive Single Amplifier Biquadratic of this type, as synthesised by Filter Free is design to the components used. The quality of a filters. The well-known Sallen and Key shown in the screenshot in Fig.10. Note that real filter will never quite match the ideal filter filter falls into this category. The basic the resistors in the circuit are 10k. This described by the mathematics. Imperfections in schematic of a second-order low pass Sallen value is determined by the R Constant value the op amp will reduce the filter’s performance and Key filter is shown in Fig.7. Positive in the Circuit Parameters section of the Filter and some filter circuits are more sensitive to single amplifier biquad filters are more Free window. If the capacitor values in the op amp imperfections than others. sensitive to component errors than op amp synthesised circuit are excessively large or The filter synthesis process determines imperfections. small, this resistance value should be changed. exact values for the resistors and capacitors in The circuit in Fig.8 is a form of the For higher order filters multiple second- the circuit. In a real circuit we can never have Sallen and Key circuit in which the order stages are used, with the addition of a these exact values because of the limitation to amplifier gain is unity. The unity-gain first order RC stage for odd-ordered filters. preferred values and component tolerances. Sallen-Key filter inherently has excellent Synthesis of filters of higher than third-order Some filter circuits are very sensitive to gain accuracy because the gain is is not available in the free version of the component values so that only a small determined by the accuracy of a resistor Nuhertz software, but may be available in difference between the required value and the ratio, as it is in Fig.7. other free filter synthesis software. NEWSAGENTS ORDER FORM Please reserve/deliver a copy of Everyday Practical Electronics for me each month
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Everyday Practical Electronics, August 2009 67 Mike Hibbett
Our periodic column for PIC programming enlightenment PIC RS232 terminal
or the last four months we have to try running it on this month’s circuit. As at a predefined location in memory. Before been looking at pushing the PIC24 we designed the keyboard library with this jumping to the interrupt routine, the CPU Fprocessor to generate video, demo- application in mind, you will see from the will store vital information about the state of nstrating how to use it to create a simple circuit diagram in Fig.1 that it is a simple the processor prior to the interrupt. 1970s arcade game. Now we will look at merging of the two previous circuits with The interrupt routine must, however, save bringing together everthing we have covered the addition of an RS232 interface. any processor registers and restore them to in the last four months for a more useful We modified the videotest.c source file their original state on exit. When the routine purpose – creating a stand alone RS232 from the video library, removing the bulk does exit, the processor restores the state terminal based on just a PIC, keyboard of the ‘main’ routine and modifying it to of the CPU to exactly how it was, and your and a television. This will make an ideal simply read a character from the keyboard software continues operation oblivious to the interface to other microprocessor circuits, and echo it to the display. Refer to Fig.2 fact that it was interrupted – except for the and the author has already found it useful for the complete application source code time that has passed. for debugging projects – the television set listing, and you can find the complete The fun starts when two interrupts occur at replacing a PC running Hyperterminal to source files on the EPE website in file exactly the same time or an interrupt occurs display debug information. video-a.zip. while the processor is already handling This code worked first time, but as expected, another interrupt, an event which is not as Software there were occasional ‘flashes’ on the display unusual as you might think. The processor The software for this article was developed while typing as a result of the keyboard has to choose one of these interrupts to in a couple of hours by progressing through interrupt blocking the time-critical video execute first, and it does this using Interrupt a series of steps, creating working code at interrupt from redrawing the display. The Priority, a simple scheme of assigning an each step. To help make this process clear, timing of the video routine is critical, and any order of preference to potential interrupt the source code for each step is available for delay results in the video timings being wrong sources. If an interrupt routine is currently download from the Library area on the EPE for a fraction of a second – but long enough running, and another lower priority interrupt website, on the usual Pic n’ Mix page. The for us to notice. Solving this requires an occurs, that new interrupt will not be serviced complete code for each step is stored in a zip understanding of how interrupts are handled, until the current one completes. file, which can be downloaded and extracted so let’s take a look at this now. Our video library uses the Timer2 onto your PC. interrupt; the keyboard library uses INT0. The source code for the actual terminal Interrupts INT0 is defined by the processor as having a application is stored in video-term. Interrupts are a means by which an higher default priority; therefore, it will occur zip, which contains both the application external device or on-board hardware first, and should a video timer interrupt occur and the two libraries. You do not need to peripheral can signal to the processor that it the processor will wait until the keyboard download the other zip files containing the would like immediate attention – through the interrupt completes before handling the new intermediate steps. CPU pausing what it is doing and jumping interrupt request. This is the wrong way round; The first step is to glue together the off to a special interrupt routine designed our keyboard can wait a few milliseconds video library with last month’s keyboard to handle that specific event. The interrupt before being serviced by an interrupt; the library into a simple test application, and routine is stored (by you, or your C compiler) video display most certainly cannot.
Fig.1. Circuit diagram of the PIC-based terminal
68 Everyday Practical Electronics, August 2009 Fig.3. Source code – serial interrupt That ‘somewhere as an array of 34 by 30 characters – almost else’ is, of course, in 1KB of RAM. We have enough space in the the serial port receive processor to store that, and writing into this interrupt routine. (You buffer is not going to be time critical. may now be beginning These requirements are easily met to appreciate interrupt through a small change to just the serial routines. Although receiver interrupt routine. Rather than calling a little tricky to PIC24VideoPutChar(), we call a new write, they solve function storeRxChar() and allow that routine Fig.2. Source code – first try difficult programming to copy the received character into the RAM problems.) Microchip’s buffer, and then transfer the entire RAM buffer Fortunately, we can assign different serial port help file comes to the rescue, to the video display buffer. storeRxChar() interrupt priorities. By default, all explaining how to write a receive interrupt can deal with scrolling by simply shifting up interrupts are set to a priority of four; we routine. You simply create a function who’s the characters stored in the RAM buffer, and can raise the Timer2 interrupt to a higher name looks like this: then adding the new character to the end of the level with a simple line of source code: void __attribute__((__interrupt__)) buffer before writing the entire contents out to IPC1bits.T2IP = 7; _U1RXInterrupt(void) the video buffer. Scrolling is quite time consuming, but the Adding this line of code immediately Don’t worry about the lengthy name, video interrupt can jump in at any time, so the after the initialisation of the two libraries it is designed to allow the C compiler to effects should not be visible. The completed raises the priority of the video interrupt to recognise that it needs to turn this into code can be found in the file video-term.zip. maximum, and results in a perfect display the serial port receive interrupt routine while typing on the keyboard. Simple once and place it at the correct position in you know how! memory. The compiler takes care of all Taking it further the register preservation and restoring; The key feature of this kind of system Serial we can write C code and ignore the other is that it gives you a big display – you will complexities. All we have to do is clear want to give up on the 2x16 LCD module Now to glue in the next piece of hardware once you have tried this out! – the serial interface. We would like the corresponding interrupt flag (to tell the processor we have responded to the One possible application would be to hook characters coming from the keyboard to go up to a mobile phone to give you a big display straight out over the serial interface, and any interrupt), read the character from the serial port and write it into the display for sending and receiving SMS messages, characters being received from the serial port without the cost and power consumption of to be displayed on the screen. We will use the buffer. The complete code for the interrupt routine is shown in Fig.3. a PC. serial port routines built into the Microchip C As a PS/2 mouse follows exactly the same compiler rather than craft our own, and the interface as a keyboard there is no reason why code is so simple it does not warrant its own Terminal application you could not add a second PS/2 socket and ‘library’ – we just include the code within the So we have solved the problem of handle a mouse as well as a keyboard, creating videotest.c source file. integrating the keyboard and video The first task is to initialise the serial libraries together, and how to interface an almost ‘PC’ like experience – albeit in text port to 9600 baud, which is done through over an RS232 serial port. Now we need only! a call to OpenUART1(). (The serial port to bind the three parts together into a Probably the most interesting application is to routines built into the C compiler are terminal application. So what is it exactly couple this with the Ethernet interface covered documented in the PIC24F UART Library that we want it to do? Here is a useful set of in earlier PIC n’ Mix articles. With just three Help File.htm help file located in the requirements that we might consider: low power ICs (PIC18F processor, ENC28J60 Microchip\MPLAB C30\docs\periph_lib ɀ Ethernet interface, PIC24H processor), one As characters are received from the could create a simple ‘thin web client’ that could directory; rather difficult to find unless you serial port, display them from top-left know where to look). access the Internet. While the features would working towards bottom right be limited, you could easily satisfy email and Having initialised the serial port, handling ɀ the keyboard data is a simple case of calling When the printing reaches the bottom instant messaging requirements for a fraction of putcUART1() for each character returned of the display, scroll the screen up a line the cost of a PC – and more importantly, for a from the keyboard followed by a call to while ɀ Interpret line feed, carriage return, fraction of the power consumption. (BusyUART1()); to ensure that the character backspace and form feed characters has been sent before we try sending another ɀ Run at 9600 baud, no parity, one stop character. PLEASE TAKE NOTE bit, one start bit (but be easy to change) Handling received characters is not so July ’09 – page 61, Fig 3. The PIC proces- simple. Our keyboard routine PIC24ps2 That should be simple enough to sor should be a type PIC24HJ128GP202 implement. As you might have guessed, keyGetKey() blocks waiting for a key to be and annotated IC2, not as shown. requiring that the screen display scrolls pressed, and so our main loop cannot also Also note, that pin 1 from the ‘prog. look to the serial receive buffer to see if data upwards when the printing reaches the end of is coming in. We will have to handle this the screen means that we need to buffer the header’ should go to pin 1 of the micro somewhere else. incoming data into a RAM buffer, arranged (IC2) – joining up with the pull-up resistor.
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Hobbyist/Student ...... £44 inc VAT PRICES Institutional (Schools/HE/FE/Industry) ...... £99 plus VAT Prices for each of the CD-ROMs above are: Institutional 10 user (Network Licence) ...... £249 plus VAT (Order form on third page) Site licence ...... £499 plus VAT (UK and EU customers add VAT at 15% to ‘plus VAT’ prices)
70 Everyday Practical Electronics, August 2009 PICmicro TUTORIALS AND PROGRAMMING HARDWAREARDWARE
VERSION 3 PICmicro MCU SPECIAL development board OFFER Suitable for use with the three software packages listed below. This flexible development board allows students to learn both how to program PICmicro microcontrollers as well as program a range of 8, 18, 28 and 40-pin devices from the 12, 16 and 18 series PICmicro ranges. For experienced programmers all programming software is included in the PPP utility that comes with the development board. For those who want to learn, choose one or all of the packages below to use with the Development Board. s Makes it easier to develop PICmicro projects s Supports low cost Flash-programmable PICmicro devices s Fully featured integrated displays – 16 individual l.e.d.s, quad 7-segment display and alphanumeric l.c.d. display s Supports PICmicro microcontrollers with A/D converters s Fully protected expansion bus for project work s USB programmable £155£155 iincludingncluding VAT and postage, suppsuppliedlied s Can be powered by USB (no power supply required) with USB cable and programming software £40 OFF Buy the Development Board together with any Hobbyist/Student or Institutional versions of the software CD-ROMs listed below and take £40 off the total (including VAT) price. SOFTWARE ASSEMBLY FOR PICmicro ‘C’ FOR 16 Series PICmicro FLOWCODE FOR PICmicro V3 Version 4 V3 Flowcode is a very high level language programming (Formerly PICtutor) The C for PICmicro microcontrollers CD-ROM is designed for students and professionals who need system for PICmicro microcontrollers based on Assembly for PICmicro microcontrollers V3.0 flowcharts. Flowcode allows you to design and to learn how to program embedded microcontrollers (previously known as PICtutor) by John Becker simulate complex systems in a matter of minutes. in C. The CD contains a course as well as all the contains a complete course in programming the A Powerful language that uses macros to facilitate software tools needed to create Hex code for a PIC16F84 PICmicro microcontroller from Arizona the control of devices like 7-segment displays, motor wide range of PICmicro devices – including a full C Microchip. It starts with fundamental concepts controllers and l.c.d.’s. The use of macros allows compiler for a wide range of PICmicro devices. and extends up to complex programs including you to control these devices without getting bogged watchdog timers, interrupts and sleep modes. Although the course focuses on the use of the down in understanding the programming. The CD makes use of the latest simulation PICmicro microcontrollers, this CD-ROM will Flowcode produces MPASM code which is techniques which provide a superb tool for provide a good grounding in C programming for compatible with virtually all PICmicro programmers. learning: the Virtual PICmicro micro-controller. this any microcontroller. When used in conjunction with the Version 3 is a simulation tool that allows users to write and s Complete course in C as well as C development board this provides a seamless solution execute MPASM assembler code for the PIC16F84 programming for PICmicro microcontrollers s that allows you to program chips in minutes. microcontroller on-screen. Using this you can Highly interactive course s Virtual C PICmicro s Requires no programming experience s actually see what happens inside the PICmicro improves understanding s Includes a C compiler Allows complex PICmicro applications to be MCU as each instruction is executed which for a wide range of PICmicro devices s Includes designed quickly s Uses international standard enhances understanding. full Integrated Development Environment s flow chart symbols s Full on-screen simulation s Comprehensive instruction through 45 tutorial Includes MPLAB software s Compatible with most allows debugging and speeds up the development sections s Includes Vlab, a Virtual PICmicro PICmicro programmers s Includes a compiler for process. microcontroller: a fully functioning simulator s all the PICmicro devices. s Facilitates learning via a full suite of Tests, exercises and projects covering a wide demonstration tutorials s Produces ASM code range of PICmicro MCU applications s Includes for a range of 18, 28 and 40-pin devices s New MPLAB assembler s Visual representation of a features in Version 3 include 16-bit arithmetic, PICmicro showing architecture and functions s strings and string manipulation, improved graphical Expert system for code entry helps first time users user interface and printing, support for 18 series s Shows data flow and fetch execute cycle and has devices, pulse width modulation, I2C, new ADC challenges (washing machine, lift, crossroads etc.) component etc. The Hobbyist/Student version is s Imports MPASM files. limited to 4K of code (8K on 18F devices)
Minimum system requirements for these items: Pentium PC running Windows 98, NT, 2000, ME, XP; CD-ROM drive; 64MB RAM; 10MB hard disk space. Flowcode will run on XP or later operating systems
Hobbyist/Student ...... £44 inc VAT PRICES InstItutional (Schools/HE/FE/Industry) ...... £99 plus VAT Institutional/Professional 10 user (Network Licence) £300 plus VAT Prices for each of the CD-ROMs above are: Site licence ...... £599 plus VAT (Order form on next page) Flowcode 10 user (Network Licence)...... £350 plus VAT Flowcode 50 user (Network Licence)...... £699 plus VAT (UK and EU customers add VAT at 15% to ‘plus VAT’ prices)
Everyday Practical Electronics, August 2009 71 SPECIAL PACKAGE OFFER DIGITAL WORKS TINA Pro V7 (Basic) + Flowcode V3 (Hobbyist/Student) 3.0
TINA Analogue, Digital, Symbolic, RF, MCU and Mixed-Mode Circuit Simulation, Testing and PCB Design £50.00 TINA Design Suite is a powerful yet affordable software package for analysing, designing and real time testing analogue, digital, MCU, and mixed electronic circuits and their PCB layouts. You can also analyse RF, inc. VAT communication, optoelectronic circuits, test and debug microcontroller applications. and p&p Enter any circuit (up to 100 nodes) within minutes with TINA’s easy-to-use schematic editor. Enhance your schematics by adding text and graphics. Choose components from the large library containing more than 10,000 manufacturer models. Analyse your circuit through more than 20 different analysis modes or with 10 high tech virtual Counter project instruments. Present your results in TINA’s sophisticated diagram windows, on virtual instruments, or in the live interactive mode where you can even edit your circuit during operation. Digital Works Version 3.0 is a graphical design tool that enables you to construct Customise presentations using TINA’s advanced drawing tools to control text, fonts, axes, line width, colour and layout. You can create, digital logic circuits and analyze their and print documents directly inside TINA or cut and paste your results into your favourite word- procesing or DTP package. behaviour. It is so simple to use that it will take you less than 10 minutes to make your TINA includes the following Virtual Instruments: Oscilloscope, Function Generator, Multimeter, Signal Analyser/Bode Plotter, Network Analyser, Spectrum Analyser, Logic Analyser, Digital Signal Generator, XY Recorder. first digital design. It is so powerful that you will never outgrow its capability s Software Flowcode V3 (Hobbyist/Student) – For details on Flowcode, see the previous page. for simulating digital logic circuits s Create your own macros – highly scalable s Create This offer gives you two seperate CD-ROMs in DVD style cases – the software will need registering (FREE) with Designsoft (TINA) and your own circuits, components, and i.c.s s Matrix Multimedia (Flowcode), details are given within the packages. Easy-to-use digital interface s Animation brings circuits to life s Vast library of logic Get TINA + Flowcode for a total of just £50, including VAT and postage. macros and 74 series i.c.s with data sheets s Powerful tool for designing and learning. Hobbyist/Student £44 inc. VAT. Institutional £99 plus VAT. PROJECT DESIGN WITH CROCODILE TECHNOLOGY Institutional 10 user £249 plus VAT. An Interactive Guide to Circuit Design Site Licence £599 plusp VAT. An interactive CD-ROM to guide you through the process of circuit design. Choose from an extensive ELECTRONIC range of input, process and output modules, including CMOS Logic, Op-Amps, PIC/PICAXE, Over 150 pages Remote Control Modules (IR and Radio), Transistors, Thyristors, Relays and much more. COMPONENTS PHOTOS Click Data for a complete guide to the pin layouts of i.c.s, transistors etc. Click More Information Over 600 images for detailed background information with many animated diagrams. A hihighgh quaqualitylity Nearly all the circuits can be instantly simulated in Crocodile Technology* (not included on selectionlti off over the CD-ROM) and you can customise the designs as required. 200 jpg images WHAT’S INCLUDED of electronic Light Modules, Temperature Modules, Sound Modules, Moisture Modules, Switch components. This Modules, Astables including 555, Remote Control (IR & Radio), Transistor Amplifiers, selection of high Thyristor, Relay, Op-Amp Modules, Logic Modules, 555 Timer, PIC/PICAXE, Output resolution photos NEW VERSION Devices, Transistor Drivers, Relay Motor Direction & Speed Control, 7 Segment can be used to Displays.Data sections with pinouts etc., Example Projects, Full Search Facility, Further enhance projects Background Information and Animated Diagrams. and presentations or to help with training and Runs in Microsoft Internet Explorer educational material. They are royalty free *All circuits can be viewed, but can only be simulated if your computer has Crocodile for use in commercial or personal printed Technoloy version 410 or later. A free trial version of Crocodile Technology can be downloaded from: www.crocodile-clips.com. projects, and can also be used royalty free Animated diagrams run without Crocodile Technology. in books, catalogues, magazine articles as Single User £39.00 inc. VAT. well as worldwide web pages (subject to Multiple Educational Users (under 500 students) £59.00 plus VAT. Over 500 students £79.00 plus VAT. restrictions – see licence for full details). (UK and EU customers add VAT at 15% to “plus VAT’’ prices) Now contains Irfan View image software for Windows, with quick-start notes included. Minimum system requirements for these CD-ROMs: Pentium PC, CD-ROM drive, 32MB RAM, 10MB hard disk Price £19.95 inc. VAT space. Windows 95/98/NT/2000/ME/XP, mouse, sound card, web browser.
Please send me: CD-ROM ORDER FORM ! ORDERING Electronic Projects ALL PRICES INCLUDE UK ! Electronic Circuits & Components V2.0 ! Analogue Electronics Version required: POSTAGE ! Digital Electronics V2.0 ! Hobbyist/Student ! Analogue Filters ! Institutional Student/Single User/Standard Version price ! ! Electronics CAD Pack Institutional/Professional 10 user includes postage to most countries in the world ! Robotics & Mechatronics ! Site licence ! Assembly for PICmicro V3 EU residents outside the UK add £5 for airmail ! ‘C’ for 16 Series PICmicro V4 postage per order ! Flowcode V3 for PICmicro ! Digital Works 3.0
! PICmicro Development Board V3 (hardware) Institutional, Multiple User and Deluxe Versions – overseas readers add £5 to the basic price of each order for airmail postage (do ! TINA Pro V7 Basic + Flowcode V3 Hobbyist/Student ! Electronic Components Photos; Version 1.1 not add VAT unless you live in an EU (European ! Note: The software on each version is the Union) country, then add 15% VAT or provide Project Design – Single User same, only the licence for use varies. ! Project Design – Multiple User (under 500 students) your official VAT registration number). ! Project Design – Multiple User (over 500 students) Send your order to: Full name: ...... Direct Book Service Address: ...... Wimborne Publishing Ltd Sequoia House, 398a Ringwood Road ...... Post code: ...... Tel. No: ...... Ferndown, Dorset BH22 9AU Signature: ...... To order by phone ring ! I enclose cheque/PO in £ sterling payable to WIMBORNE PUBLISHING LTD for £ ...... 01202 873872. Fax: 01202 874562 ! Please charge my Visa/Mastercard/Maestro: £ ...... Goods are normally sent within seven days Valid From: ...... Card expiry date: ...... E-mail: [email protected] Online shop: Card No: ...... Maestro Issue No...... www.epemag.com Card Security Code ...... (The last 3 digits on or just under the signature strip)
72 Everyday Practical Electronics, August 2009 READOUT Email:E [email protected] MattM Pulzer addresses some of the ggeneral points readers have raised. HHave you anything interesting to say?? WIN AN ATLAS LCR ANALYSER WORTH £79 DDrop us a line! An Atlas LCR Passive Component Analyser, kindly donated by Peak Electronic Design Ltd, will be awarded to the author of the Letter Of The Month. All letters quoted q oted here have previously been replied to directly The Atlas LCR automatically measures to 2M inductance with from 1mH to 10H, capacitance from 1pF to 10,000 F and resistance from 1 a basic accuracy of 1%. www.peakelec.co.uk
Chat Zone issues Dear EPE LETTER OF THE MONTH Two points: first, I tried to post a message to Alan Winstanley via the Chat Zone, but couldn’t start a thread in the Recycle It! joined them at the end and glued a third ‘report a problem section’, or reply to his piece of plastic to the end. I mounted this notice there – hence this email. Dear EPE contraption on a wooden ‘bridge’ that sits Second, be aware that the EPE site is Recycle It! – I love this part of EPE. on my etching tank. Last, I connected blacklisted by the content-monitoring Since you request readers to tell you the system to a 5V power supply and software used by my local public library about this type of project… here is one voila, an unattended flow control for the (and presumably by other libraries and from me. etching fluid. educational establishments). The reason is I had an old PC-CD player that Harm, Netherlands, by email the presence of ‘Chat Zone’ (indiscriminately stopped working. So, I took out the deemed unsuitable for children). frame that contained the motor and Well done Harm – an excellent example of It’s a shame that such a valuable gearbox which operates the tray. I glued ingenious recycling. We’d love to hear about educational resource as EPE is denied two pieces of plastic to the last gear, other readers’ ideas. to children and others, as more recruits (particularly younger ones) to the hobby of electronics should be encouraged. Perhaps a change of name for Chat Zone would get round this blacklisting... or maybe not if the nannying software checks for site script behaviour, rather than just keywords such as ‘chat’. Any thoughts? Geoff (aka Alec_t), by email
Many thanks for your email Geoff. I am aware of the problem sometimes encountered with over-zealous public-access Internet terminals screening out our forum. Unfortunately, I can’t see a suitable work- around. The software is deeply entrenched on the server under chatzones.co.uk and we can’t migrate the forum to another domain name. It might be worth trying to access it via www.epemag.com and use the Chat Zone link across the top to launch the forum in a ‘frame’, assuming the public access terminal will allow that. There is also a direct link at the bottom right of the EPE home page. The problem is, old meters have Terry – age is no barrier to (or excuse I did try to reproduce the issue with the electronic components that are difficult, for avoiding!) electronics. I am quite ‘report a problem’ section – I logged in and if not impossible to source. In my sure that if you’ve mastered a technically posted a test message (previewed it anyway) younger days, just about every high demanding skill such as photography, so I’m currently a bit stuck on that. street had a shop selling resistors, valves, and are able to solder, then with a bit of Thank you for your interest, Alan Winstanley and other bits and pieces. Component persistence electronics should not be a cannibalism means that you have to junk problem. Yes, it can appear intimidating at Let there be light (measurement) one device to restore another, and that is first, but there are plenty of good books and a pity, especially if the original has been courses for novices. Wimborne Publishing Dear EPE superbly made. produces quite a range of respected, tried I know nothing about electronics and just At present, I am trying to restore a and tested, and practical educational looking through your magazine makes me feel Gossen exposure meter in which the CdS material – why not call the office to discuss that to attempt it would be beyond my OAP light receptor resistor has died. However, your needs: 01202 873872, or see the book capabilities. However, I can solder wires and I am having a time of it trying to find a and CD-ROM pages in this issue. this is about as far as I go when repairing old replacement. Where do I start looking? As for sourcing CdS cells – do any camera equipment such as exposure meters. Terry Buchanan, by email readers have any tips?
Everyday Practical Electronics, August 2009 73 Surfing The Internet Net Work Alan Winstanley
The more things change… death in a ‘car clash’ involving one of his customers. On the same day Mr Stanley Gunther Turner (British citizen) has a safety deposit box bursting More than a decade after the Melissa worm wriggled its way into with $105 million and a Miss Hellen Kaloum, or is it Miss Nina Nijaro the news headlines, unwanted spam continues to plague the inboxes as it says in the body text, is sat on $2.5 million somewhere in the Ivory of every email user. Melissa, old hands might remember, unleashed Coast. fear and havoc in its time; it was a self-propagating Word 97 macro Good news! Western Union has $700,000 heading for my email address that emailed itself to the first 50 Outlook addresses on an infected and the money has come direct from the International Monetary Fund! The machine before promptly re-mailing itself out again. Unlike viruses, IMF states (it says here) that they choose to send it to me through Western strictly speaking ‘worms’ do not damage file systems per se, they Union instead of courier services because there are so many fake couriers simply reproduce until the system grinds to a halt. Melissa was initially around. I have also been awarded compensation by the United Nations, propagated by a single posting onto Usenet (newsgroups) through a and I also welcome the efforts of one Dr Davis William to help me with compromised AOL account, before going on to choke mail servers an ATM card that has been charged up with $1.5 million, but has only everywhere. Melissa’s creator, David Smith, was initially sentenced to three days left before expiring. Mrs Steffany Clinton desires to transfer 10 years in prison in recognition of his creativity. $700,000 to me in $5,000 tranches. A US soldier (Sgt Baker Johnson Today, our Internet world is more fraught and dangerous than ever, with Jr, but with a Japanese Yahoo address) expressed a wish to smuggle $10 users facing constant threats from viruses, phishing attacks, dangerous million out of Iraq. As if I’m not rolling in dough already, a few minutes websites that plant security-compromising files on your computer, identity ago I won $485,000 in a ‘Yahoo MSN Live lottery’. theft, keystroke loggers and plain old-fashioned fraud. The need for This lunacy continues unabated even as I write, but the biggest constant vigilance coupled with the sheer volume of unwanted ‘noise’ has tragedy is that some otherwise rational and sensible people still fall for damaged the potential usability of the Internet enormously. it. This 419 or ‘Advance Fee Fraud’ wreaks misery on its gullible and The professional antispam filtering service MessageLabs (www. greedy victims and these highly adaptable perpetrators are supremely messagelabs.co.uk), now owned by Symantec, reported in a monthly skilled in milking mercilessly those who are sucked in by these scams, Intelligence bulletin that spam had reached a 19 month high, with a by fleecing them with elaborate plots involving authentic-looking worrying (and annoying) return of ‘image spam’ – emailing a JPEG or forged documents or demands for progress payments. I have even GIF spam advert, typically for Viagra or pharmacy meds, in the body of known an industrial acquaintance, who should have known better, a spam email. As antispam software cannot readily scan an inline image, almost fall for it: he was getting ready to phone the villain on a mobile the message often slips through undetected. In April 2009, Messagelabs number until I stopped him. reported that spam afflicted nearly 86% of all messages it scanned, with Most of us – especially EPE Net Work readers – know how to one in 305 containing a virus and one in 400 being a phishing scam, says recognise these deceptive emails; don’t we! The critical rule is that you the spam filtering firm. My ClearMyMail control panel states that 91% should never engage with such people. They do not merely work from of my inbound email has been spam, and I notice clear ‘spikes’ in spam some Nigerian Internet café: in Europe, gangs of them operate typically on some days. out of London or Rotterdam and they are highly mobile. My trusty old Eudora Email It is quite possible that one’s personal software does a fair job of shifting safety can be put at risk, yet victims spam into its Junk folder, where the really have arranged to meet at hotels manic mutterings of various Nigerian to exchange suitcases full of ‘cash’. A fraudsters accumulate periodically. If 22-year-old Canadian, John Rempel, nothing else, this Nigerian ‘419’ fraud really did divest himself, his friends provides some light entertainment and relatives of $150,000 when chasing value: 419 spam seems to arrive in tidal down a $12 million ‘inheritance’, which waves, and one can imagine a whole included buying a ‘magic cleansing gang of hopefuls feverishly dreaming liquid’ that ‘activated’ piles of paper up the most unlikely yarns in a Lagos money. Internet café. Ten years after fighting off Melissa, we face ever more insidious threats A plateful of spam to our personal accounts, identity and In recognition of the creative skills safety. The rule remains that if something of these people, my compliments sounds too good to be true then it go to Dr John Atkin, who seeks my invariably is. However, by being vigilant help in transferring $800,000 to a and following your honest instincts, and Swiss account. I must contact his maintaining antivirus software as up to secretary Dr Christopher Albert, who date as possible, you can avoid falling unfortunately quotes a Hong Kong into the clutches of these villains. The Yahoo email account having a different Internet has myriad uses, but you must name altogether. Not to be outdone, his tread carefully. buddy on the next café computer, Dr Don’t forget to check our website at Ibrahim Abuya of the Benin Republic, The MessageLabs website offers an insight into www.epemag.com, and you can email has $15 million to shift following the prevailing virus and spam trends me at [email protected]
74 Everyday Practical Electronics, August 2009 DIRECT BOOK SERVICE Electronics Teach-In + FREE CD-ROM CIRCUITS AND DESIGN
Mike Tooley A BEGINNER’S GUIDE TO TTL DIGITAL ICs A broad-based introductionon R. A. Penfold to electronics – find outut This book first covers the basics of simple logic circuits The books listed have been how circuits work and whatat in general, and then progresses to specific TTL logic selected by Everyday Practical goes on inside them. Plusus integrated circuits. The devices covered include gates, 15 easy-to-build projects.s. oscillators, timers, flip/flops, dividers, and decoder circuits. Electronics editorial staff as The 152 page A4 bookk Some practical circuits are used to illustrate the use of TTL being of special interest to comes with a free CD-- devices in the “real world’’. ROM containing the wholee 142 pages Order code BP332 £5.45 everyone involved in electronics Teach-In 2006 seriess and computing. They are (originally published PRACTICAL ELECTRONICS CALCULATIONS in EPE) in PDF form, AND FORMULAE supplied by mail order direct to interactive quizzes to test F. A. Wilson, C.G.I.A., C.Eng., F.I.E.E., F.I.E.R.E., F.B.I.M. your knowledge, TINA Bridges the gap between complicated technical theory, and your door. Full ordering details circuit simulation software “cut-and-tried’’ methods which may bring success in design are given on the last book page. (a limited version – plus but leave the experimenter unfulfilled. A strong practical a specially written TINANA bias – tedious and higher mathematics have been avoided Tutorial), together with simulations of the circuits in the where possible and many tables have been included. FOR A FURTHER SELECTION Teach-In series, plus Flowcode (a limited version) a high The book is divided into six basic sections: Units and level programming system for PIC microcontrollers based Constants, Direct-Current Circuits, Passive Components, OF BOOKS AND CDROMS on flowcharts. Alternating-Current Circuits, Networks and Theorems, The Teach-In series covers everything from Electric Measurements. SEE THE SHOP ON OUR UK Current through to Microprocessors and Microcontrollers 256 pages Order code BP53 £5.49 and each part includes demonstration circuits to build on WEBSITE breadboards or to simulate on your PC. MICROCONTROLLER COOKBOOK In addition to the Teach-In series, the book includes 15 Mike James CMOS-based simple projects from the Back-To-Basics The practical solutions to real problems shown in this www.epemag.com series by Bart Trepak, these are: Fridge/Freezer Alarm, cookbook provide the basis to make PIC and 8051 devices Water Level Detector, Burglar Alarm, Scarecrow, Digital really work. Capabilities of the variants are examined, and Lock, Doorchime, Electronic Dice, Kitchen Timer, Room ways to enhance these are shown. A survey of common All prices include UK Thermometer, Daily Reminder, Whistle Switch, Parking interface devices, and a description of programming Radar, Telephone Switch, Noughts and Crosses Enigma models, lead on to a section on development techniques. 2 postage and a Weather Vane. There is also a MW/LW Radio project The cookbook offers an introduction that will allow any user, in the Teach-In series. novice or experienced, to make the most of microcontrollers. 152 pages + CD-ROM Order code ETI £8.50 240 pages Order code NE26 £25.99 EASYSCCSO PC CASE MODDING G R.A Penfold Why not turn that anonymous grey tower, that is the heart of your computer system, into a source of visual wonderment and fascination. To start, you need to change the case or some case COMPUTING AND ROBOTICS panels for ones that are transparent. This will then allow the inside of your computer and it’s working parts to be clearly visible. There are now numerous accessories that are relatively inexpensive and freely available, for those wishing to WINDOWS XP EXPLAINED EXPLAINED avoidavvoid objects by using ‘bats radar’, radar’ or accurately follow a line customise their PC with added colour and light. Cables and N. Kantaris and P. R. M. Oliver marked on the floor. Learn to use additional types of sensors fans can be made to glow, interior lights can be added, and it If you want to know what to do next when confronted with including rotation, light, temperature, sound and ultrasonic and can all be seen to good effect through the transparent case. Microsoft’s Windows XP screen, then this book is for you. It also explore the possibilities provided by using an additional Exterior lighting and many other attractive accessories may applies to both the Professional and home editions. (third) motor. For the less experienced, RCX code programs also be fitted. The book was written with the non-expert, busy person in accompany most of the featured robots. However, the more This, in essence, is case modding or PC Customising as mind. it explains what hardware requirements you need adventurous reader is also shown how to write programs it is sometimes called and this book provides all the practical in order to run Windows XP successfully, and gives an using Microsoft’s VisualBASIC running with the ActiveX control details you need for using the main types of case modding overview of the Windows XP environment. (Spirit.OCX) that is provided with the RIS kit. components including:- Electro luminescent (EL) ‘go-faster’ The book explains: How to manipulate Windows, and Detailed building instructions are provided for the featured stripes: Internal lighting units: Fancy EL panels: Data cables how to use the Control Panel to add or change your printer, robots, including numerous step-by-step photographs. The with built-in lighting: Data cables that glow with the aid of ‘black’ and control your display; How to control information using designs include rover vehicles, a virtual pet, a robot arm, an light from an ultraviolet (UV) tube: Digital display panels: LED WordPad, notepad and paint, and how to use the Clipboard ‘intelligent’ sweet dispenser and a colour conscious robot case and heatsink fans: Coloured power supply covers. facility to transfer information between Windows applications; that will try to grab objects of a specific colour. How to be in control of your filing system using Windows 192 pages + CD-ROM Order code BP542 £8.99 Explorer and My Computer; How to control printers, fonts, 298 pages Order code BP902 £14.99 ROBOT BUILDERS COOKBOOK characters, multimedia and images, and how to add hardware THE PIC MICROCONTROLLER and software to your system; How to configure your system to Owen Bishop YOUR PERSONAL INTRODUCTORY COURSE This is a project book and guide for anyone who wants to communicate with the outside world, and use Outlook Express – THIRD EDITION John Morton for all your email requirements; how to use the Windows Media build and design robots that work first time. Discover the potential of the PIC microcontroller through Player 8 to play your CDs, burn CDs with your favourite tracks, With this book you can get up and running quickly, building graded projects – this book could revolutionise your use the Radio Tuner, transfer your videos to your PC, and how fun and intriguing robots from step-by-step instructions. electronics construction work! to use the Sound Recorder and Movie Maker; How to use the Through hands-on project work, Owen introduces the A uniquely concise and practical guide to getting up and System Tools to restore your system to a previously working programming, electronics and mechanics involved in practical running with the PIC Microcontroller. The PIC is one of the state, using Microsoft’s Website to update your Windows set- robot design-and-build. The use of the PIC microcontroller most popular of the microcontrollers that are transforming up, how to clean up, defragment and scan your hard disk, and electronic project work and product design. throughout provides a painless introduction to programming – how to backup and restore your data; How to successfully Assuming no prior knowledge of microcontrollers and harnessing the power of a highly popular microcontroller used transfer text from those old but cherished MS-DOS programs. introducing the PICs capabilities through simple projects, by students, hobbyists and design engineers worldwide. Ideal for first-time robot builders, advanced builders wanting 264 pages Order code BP514 £7.99 this book is ideal for use in schools and colleges. It is the ideal introduction for students, teachers, technicians and to know more about programming robots, and students INTRODUCING ROBOTICS WITH LEGO electronics enthusiasts. The step-by-step explanations tackling microcontroller-based practical work and labs. MINDSTORMS make it ideal for self-study too: this is not a reference book The book’s companion website at http://books.elsevier. Robert Penfold – you start work with the PIC straight away. com/companions/9780750665568 contains: downloadable Shows the reader how to build a variety of increasingly The revised third edition covers the popular files of all the programs and subroutines; program listings sophisticated computer controlled robots using the brilliant Lego reprogrammable Flash PICs: 16F54/16F84 as well as the for the Quester and the Gantry robots that are too long to be Mindstorms Robotic Invention System (RIS). Initially covers 12F508 and 12F675. included in the book. fundamental building techniques and mechanics needed to construct strong and efficient robots using the various “click- 270 pages Order code NE36 £20.99 366 pages Order code NE46 £21.99 together’’ components supplied in the basic RIS kit. explains in INTRODUCTION TO MICROPROCESSORS AND NEWNES INTERFACING COMPANION simple terms how the “brain’’ of the robot may be programmed MICROCONTROLLERS – SECOND EDITION Tony Fischer-Cripps on screen using a PC and “zapped’’ to the robot over an infra- John Crisp A uniquely concise and practical guide to the hardware, red link. Also, shows how a more sophisticated Windows If you are, or soon will be, involved in the use of microprocessors applications and design issues involved in computer programming language such as Visual BASIC may be used to and microcontrollers, this practical introduction is essential control the robots. interfacing and the use of transducers and instrumentation. reading. This book provides a thoroughly readable introduction Newnes Interfacing Companion presents the essential Detailed building and programming instructions provided, to microprocessors and micrcontrollers. Assuming no previous including numerous step-by-step photographs. information needed to design a PC-based interfacing system knowledge of the subject, nor a technical or mathematical from the selection of suitable transducers, to collection of data, 288 pages + Large Format Order code BP901 £14.99 background. It is suitable for students, technicians, engineers and the appropriate signal processing and conditioning. and hobbyists, and covers the full range of modern micros. Contents: Part 1 – Transducers; Measurement systems; MORE ADVANCED ROBOTICS WITH LEGO After a thorough introduction to the subject, ideas are MINDSTORMS – Robert Penfold developed progressively in a well-structured format. All Temperature; Light; Position and motion; Force, pressure Shows the reader how to technical terms are carefully introduced and subjects which and flow. Part 2 – Interfacing; Number systems; Computer extend the capabilities of the Covers the Vision have proved difficult, for example 2’s complement, are architecture; Assembly language; Interfacing; A to D and brilliant Lego Mindstorms command system clearly explained. John Crisp covers the complete range of D to A conversions; Data communications; Programmable Robotic Invention System microprocessors from the popular 4-bit and 8-bit designs to logic controllers; Data acquisition project. Part 3 – Signal (RIS) by using lego’s own today’s super-fast 32-bit and 64-bit versions that power PCs processing; Transfer function; Active filters; Instrumentation accessories and some simplee home constructed unitsunits. You and engine management systems etc. amplifier; Noise; Digital signal processing. will be able to build robots that can provide you with ‘waiter service’ when you clap your hands, perform tricks, ‘see’ and 222 pages Order code NE31 £22.00 295 pages Order code NE38 £35.99
Everyday Practical Electronics, August 2009 75 THEORY AND REFERENCE
THE AMATEUR SCIENTIST CD-ROM ELECTRONIC TEST EQUIPMENT HANDBOOK The complete collection of The Amateur Scientist articles from CD-ROM Steve Money Scientific American magazine. Over 1,000 classic science projects In most applications of electronics, test instruments are essential for checking the performance from a renowned source of winning projects. All projectss are of a system or for diagnosing faults in operation, and so it is important for engineers, rated for cost, difficulty and possible hazards. technicians, students and hobbyists to understand how the basic test instruments work and Plus over 1,000 pages of helpful science techniques thatt how they can be used. never appeared in Scientific American. The principles of operation of the various types of test instrument are explained in simple Exciting science projects in: Astronomy; Earth Science; terms with a minimum of mathematical analysis. The book covers analogue and digital meters, Biology; Physics; Chemistry; Weather . . . and much bridges, oscilloscopes, signal generators, counters, timers and frequency measurement. The more! The most complete resource ever assembled for practical uses of these instruments are also examined. hobbyists, and professionals looking for novel solutions 206 pages Order code PC109 £9.95 to research problems. Includes extensive Science Software Library with even UNDERSTANDING ELECTRONIC CONTROL SYSTEMS more science tools. Suitable for Mac, Windows, Linux Owen Bishop or UNIX. 32MB RAM minimum, Netscape 4.0 or higher orr Owen Bishop has produced a concise, readable text to introduce a wide range of students, Internet Explorer 4.0 or higher. technicians and professionals to an important area of electronics. Control is a highly mathematical subject, but here maths is kept to a minimum, with flow charts to illustrate Over 1,000 projects Orderer code AS1 CCD-ROMDRROOM £19.95£19 95 principles and techniques instead of equations. OSCILLOSCOPES – FIFTH EDITION Cutting edge topics such as microcontrollers, neural networks and fuzzy control are all here, Ian Hickman making this an ideal refresher course for those working in Industry. Basic principles, control Oscilloscopes are essential tools for checking circuit operation and diagnosing faults, and an algorithms and hardwired control systems are also fully covered so the resulting book is a enormous range of models are available. comprehensive text and well suited to college courses or background reading for university This handy guide to oscilloscopes is essential reading for anyone who has to use a ’scope students. for their work or hobby; electronics designers, technicians, anyone in industry involved in test The text is supported by questions under the headings Keeping Up and Test Your Knowledge and measurement, electronics enthusiasts . . . Ian Hickman’s review of all the latest types of so that the reader can develop a sound understanding and the ability to apply the techniques ’scope currently available will prove especially useful for anyone planning to buy – or even they are learning. build – an oscilloscope. 228 pages Order code NE35 £24.99 The contents include a description of the basic oscillscope; Advanced real-time oscilloscope; Accessories; Using oscilloscopes; Sampling oscilloscopes; Digital storage oscilloscopes; Oscilloscopes for special purposes; How oscillocopes work (1): the CRT; How oscilloscopes work (2): circuitry; How oscilloscopes work (3): storage CRTs; plus a listing of Oscilloscope manufacturers and suppliers. ALL PRICES INCLUDE 288 pages Order code NE37 £25.99 UK POST & PACKING
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HOW TO FIX YOUR PC PROBLEMS R.A. Penfold the most from your laptop PC in an easy and enjoyable way. It is written in plain English What do you do when your laptop or desktop stops working properly. Do you panic, try to and wherever possible avoids technical jargon. find the answer on the page of fault finding tips you may find at the back of the manufacturers Among the many topics covered are: Choosing a laptop that suits your particular needs. manual. Or do you spend hours trying to get through to a telephone helpline or waste even Getting your new computer set up properly. Customising your computer so that it is optimised more time waiting for an email reply from a helpdesk. for your particular needs. Setting up and dealing with user accounts. Using the Windows Well help is now at hand! This book will assist you in identifying the type of problem, ‘Ease of Access Center’. Optimising the life and condition of your battery. Keeping the whether it’s hardware, software or a peripheral that is playing up? Once the fault has been operating system and other software fully up-to-date. Troubleshooting common problems. Keeping your computer and data safe and secure. And much more besides... identified, the book will then show you how to go about fixing it. This book uses plain English Even though this book is written for the older generation, it is also suitable for anyone of and avoids technical jargon wherever possible. It is also written in a practical and friendly any age who has a laptop or is thinking of buying one. It is written for computers that use manner and is logically arranged for easy reference. Windows Vista as their operating system but much will still apply to Windows XP machines. The book is divided into four main sections and among the many topics covered are: Printed in full colour on high quality non-refective paper Common problems with Windows Vista operating system not covered in other chapters. Also covers to a lesser extent Windows XP problems. Sorting out problems with ports, 120 pages Order code BP702 £8.49 peripherals and leads. Also covers device drivers software and using monitoring software. Common problems with hard disc drives including partitioning and formatting a new drive. AN INTRODUCTION TO EXCEL SPREADSHEETS Jim Gatenby Using system restore and recovering files. Also covers CD-ROM and Flash drives. Common The practical and friendly approach of this book will help newcomers to easily learn problems with sound and video, including getting a multi-speaker system set up correctly. and understand the basics of spreadsheets. This book is based on Microsoft’s Excel 2007 An extremely useful addition to the library of all computer users, as you never know when spreadsheet, but much of the book will still apply to earlier versions of Excel. The book is a fault may occur! written in plain English, avoiding technical and mathematical jargon and all illustrations are Printed in full colour on high quality non-refective paper in full colour. It is suitable for all age groups from youngsters to the older generation. 128 pages Order code BP705 £8.49 Among the many topics explained are how to: Install the software. Use the exciting new features of Excel 2007. Create and use a spreadsheet. Enter, edit and format text, numbers AN INTRODUCTION TO WINDOWS VISTA P.R.M. Oliver and N. Kantarris and formulae. Insert and delete columns and rows. Save and print a spreadsheet. Present If you have recently bought a new desktop or laptop it will almost certainly have Windows the information on a spreadsheet as a graph or chart. Manage and safeguard Excel files on as its operating system. Windows Vista manages the available resource of a computer and disc. Use Excel as a simple database for names and addresses. also ‘controls’ the programs that run on it. This book will help you to quickly gain confidence and get to grips with using spreadsheets. To get the most from your computer, it is important that you have a good understanding of In fact, you will wonder how you ever managed without them. Vista. This book will help you acheive just that. It is written in a friendly and practical way and Printed in full colour on high quality non-reflective paper. is suitable for all age groups from youngsters to the older generation. It has been assumed that Vista is installed and running on your computer. 118 pages Order code BP701 £8.49 Among the numerous topics explained are: The Vista environment with its many windows. How to organise your files, folders and photos. How to use Internet Explorer for your web AN INTRODUCTION TO DIGITAL PHOTOGRAPHY WITH VISTA R.A. Penfold browsing. How to use Microsoft Mail for your emails. How to control your PC and keep it The friendly and practical approach of this book will help newcomers to digital healthy. How to use Vista’s Accessibility features if you have poor eye sight or difficulty in photography and computing to easily learn the basics they will need when using a using the keyboard or mouse. And much more besides.... digital camera with a laptop or desktop PC. It is assumed that your PC uses Windows With the help of this book you will easily and enjoyably gain a better understanding of Vista, however, if it is a Windows XP machine the vast majority of this book will still Microsoft’s amazing Windows Vista operating system. apply. The book is written in plain English, avoiding Printed in full colour on high quality non-refective paper technical jargon and all illustrations are in full colour. It is suitable for all age groups from youngsters to the 120 pages Order code BP703 £8.49 older generation. Among the many topics explained are how to: Understand the basic features of a digital camera. COMPUTING WITH A LAPTOP FOR THE OLDER Transfer photographs from your digital camera to your GENERATION R.A. Penfold computer. View your photographs. Save, sort and file Laptop computers have rapidly fallen in price, increased your photographs. Manipulate, crop and carry out simple in specification and performance and become much lighter corrections to your photographs. Copy your photographs in weight. They can be used practically anywhere, then stored away out of sight. It is therefore, not surprising that on to CD or DVD. Print your photographs. Share images laptop sales now far exceed those of desktop machines and with family and friends anywhere in the world by email or that they are increasingly becoming the machine of choice with an online album. for the older generation. This book will help you quickly get to grips with, gain You may want to use your laptop as your main computer confidence and expand your horizons in the fascinating or as an extra machine. You may want to use your laptop hobby of digital photography. on the move, at home, at work or on holiday. Whatever Printed in full colour on high quality non-reflective paper. your specific requirements are, the friendly and practical approach of this book will help you to understand and get 120 pages Order code BP700 £8.49
76 Everyday Practical Electronics, August 2009 PROJECT BUILDING
ELECTRONIC PROJECTS FOR EXPERIMENTERS STARTING ELECTRONICS, THIRD EDITION R. A. Penfold Keith Brindley Many electronic hobbyists who have been pursuing their A punchy practical introduction to self-build electronics. The hobby for a number of years seem to suffer from the ideal starting point for home experimenters, technicians and dreaded “seen it all before’’ syndrome. This book is fairly students who want to develop the real hands-on skills of and squarely aimed at sufferers of this complaint, plus any electronics construction. other electronics enthusiasts who yearn to try something A highly practical introduction for hobbyists, students, a bit different. and technicians. Keith Brindley introduces readers to the functions of the main component types, their uses, and the The subjects covered include:- Magnetic field detector, basic principles of building and designing electronic circuits. Basic Hall effect compass, Hall effect audio isolator, Breadboarding layouts make this very much a ready-to- Voice scrambler/descrambler, Bat detector, Bat style echo run book for the experimenter, and the use of multimeter, location, Noise cancelling, LED stroboscope, Infra-red but not oscilloscopes, and readily available, inexpensive “torch’’, Electronic breeze detector, Class D power amplifier, components makes the practical work achievable in a home Strain gauge amplifier, Super hearing aid. or school setting as well as a fully equiped lab. 138 pages Order code BP371 £5.45 288 pages Order code NE42 £12.99 BUILDING VALVE AMPLIFIERS Morgan Jones PRACTICAL FIBREFIBRE-OPTIC OPTIC PROJECTS P VIDEO PROJECTS FOR THE ELECTRONICS CONSTRUCTOR The practical guide to building, modifying, fault-finding and R. A. Penfold R. A. Penfold repairing valve amplifiers. A hands-on approach to valve While fibre-optic cables may have potential advantages over ordinary electric cables, for the electronics enthusiast Written by highly respected author R. A. Penfold, this electronics – classic and modern – with a minimum of theory. book contains a collection of electronic projects specially it is probably their novelty value that makes them worthy Planning, fault-finding, and testing are each illustrated by designed for video enthusiasts. All the projects can be simply step-by-step examples. of exploration. Fibre-optic cables provide an innovative constructed, and most are suitable for the newcomer to A unique hands-on guide for anyone working with valve (tube interesting alternative to electric cables, but in most cases project construction, as they are assembled on stripboard. in USA) audio equipment – as an electronics experimenter, they also represent a practical approach to the problem. There are faders, wipers and effects units which will add audiophile or audio engineer. This book provides a number of tried and tested circuits for sparkle and originality to your video recordings, an audio mixer Particular attention has been paid to answering questions projects that utilize fibre-optic cables. and noise reducer to enhance your soundtracks and a basic commonly asked by newcomers to the world of the vacuum The projects include:- Simple audio links, F.M. audio link, computer control interface. Also, there’s a useful selection on tube, whether audio enthusiasts tackling their first build, or P.W.M. audio links, Simple d.c. links, P.W.M. d.c. link, P.W.M. basic video production techniques to get you started. more experienced amplifier designers seeking to learn the motor speed control, RS232C data links, MIDI link, Loop Circuits include: video enhancer, improved video enhancer, ropes of working with valves. The practical side of this book alarms, R.P.M. meter. video fader, horizontal wiper, improved video wiper, negative is reinforced by numerous clear illustrations throughout. All the components used in these designs are readily video unit, fade to grey unit, black and white keyer, vertical wiper, audio mixer, stereo headphone amplifier, dynamic available, none of them require the constructor to take out 368 pages Order code NE40 £23.99 noise reducer, automatic fader, pushbutton fader, computer a second mortgage. control interface, 12 volt mains power supply. 132 pages Order code BP374 £5.45 124 pages Order code PC115 £5.45 THEORY AND REFERENCE BOOK ORDERING DETAILS All prices include UK postage. for postage to Europe (air) and the rest of the world (surface) please add £2 per book. For the rest of the world airmail add £3 per book. Note: Overseas surface mail GETTING THE MOST FROM YOUR MULTIMETER postage can take up to 10 weeks. CD-ROM prices include VAT and/or postage to anywhere in the R. A. Penfold world. Send a PO, cheque, international money order (£ sterling only) made payable to Direct Book This book is primarily aimed at beginners and those of limited experience of electronics. Chapter 1 covers the Service or card details, Visa, Mastercard or Maestro to: basics of analogue and digital multimeters, discussing the relative merits and the limitations of the two types. DIRECT BOOK SERVICE, WIMBORNE PUBLISHING LIMITED, SEQUOIA HOUSE, 398a In Chapter 2 various methods of component checking RINGWOOD ROAD, FERNDOWN, DORSET BH22 9AU. are described, including tests for transistors, thyristors, resistors, capacitors and diodes. Circuit testing is covered Books are normally sent within seven days of receipt of order, but please allow 28 days for delivery – more for overseas orders. in Chapter 3, with subjects such as voltage, current and Please check price and availability (see latest issue of Everyday Practical Electronics) before ordering from old lists. continuity checks being discussed. In the main little or no previous knowledge or experience For a further selection of books see the next two issues of EPE. is assumed. Using these simple component and circuit Tel 01202 873872 Fax 01202 874562. Email: [email protected] testing techniques the reader should be able to confidently tackle servicing of most electronic projects. Order from our online shop at: www.epemag.com
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Everyday Practical Electronics, August 2009 77 PCB SERVICE PROJECT TITLE ORDER CODE COST APRIL ’09 Versatile 4-Input Mixer 704 £10.31 , Oscar Noughts & Crosses Machine 705 £7.29 Printed circuit boards for most recent EPE constructional projects are available , GPS-Based Frequency Reference from the PCB Service, see list. These are fabricated in glass fibre, and are fully – Main Board 706 set £11.10 drilled and roller tinned. Double-sided boards are NOT plated through hole – Display Board 707 and will require ‘vias’ and some components soldering to both sides. All prices include VAT and postage and packing. Add £1 per board for airmail outside of MAY ’09 Europe. Remittances should be sent to The PCB Service, Everyday Practical Infrared Audio Headphone Link 708 set £9.20 Electronics, Wimborne Publishing Ltd., Sequoia House, 398a Ringwood 709 Road, Ferndown, Dorset BH22 9AU. Tel: 01202 873872; Fax 01202 874562; Microstepping Unipolar Stepping Motor Driver 710 £7.49 Email: [email protected]. On-line Shop: www.epemag.com. JUNE ’09 Cheques should be crossed and made payable to Everyday Practical Electronics , Spectacular Bike Wheel POV Display 711 (set of 3) £23.73 (Payment in £ sterling only). (double-sided) NOTE: While 95% of our boards are held in stock and are dispatched , within seven days of receipt of order, please allow a maximum of 28 days Remote Volume Control & Preamplifier Module for delivery – overseas readers allow extra if ordered by surface mail. – Main Board 714 Back numbers or photocopies of articles are available if required – see the – Display Board 715 set £9.20 Back Issues page for details. WE DO NOT SUPPLY KITS OR COMPONENTS – Power Supply Board 716 FOR OUR PROJECTS. JULY ’09 Please check price and availability in the , Solar Water Heating System Controller latest issue. A large number of older boards are – Main Board 712 set £15.00 listed on, and can be ordered from, our website. – Display Board 713 Boards can only be supplied on a payment with order basis. , PIC Probe (double-sided) 717 £9.50 , Simple Data-Logging Weather Station – Main Board 718 PROJECT TITLE ORDER CODE COST set £6.66 – RS232 Board 719 MAY ’08 AUGUST ’09 ,PC-Controlled Burglar Alarm – Keypad 668 £6.18 , ,Fast Charger For NiMH Batteries 720 £6.66 Electric Mobility Buggy Monitor 669 £6.02 , Mini Theremin 670 £10.15 Rolling Code Keyless Entry System – Main Board 721 £7.29 JUNE ’08 set £11.89 – Transmitter (2off) 722 (2off) £6.18 , Monopoly Money 671 £7.30 , Universal High-Energy LED Lighting System 673 £6.82 JULY ’08 , PIC MIDI Sound Wave Generator 672 £11.20 Galactic Voice 674 £6.82 EPE SOFTWARE Coolmaster 675 £6.34 , All software programs for EPE Projects marked with a AUGUST ’08 star, and others previously published can be downloaded Four-Channel A/V Selector 676 £9.51 free from the Library on our website, accessible via our DC Relay Switch For High Current Loads 677 £6.02 home page at: www.epemag.com Versatile Temperature Switch 678 £6.66 , Mains Monitor – Monitor 679 £7.13 – Interface 680 £5.71 SEPTEMBER ’08 PCB MASTERS Magnetic Cartridge Preamplifier 681 £7.45 , Super Speedo Corrector 682 £6.66 PCB masters for boards published from the March ’06 issue Ultrasonic Eavesdropper 683 £6.82 onwards can also be downloaded from our website (www. S-Video To Composite Video Converter (double-sided) 684 £9.98 epemag.com); go to the ‘Library’ section. OCTOBER ’08 , Inteligent Car Air-Conditioner Controller 685 £6.66 , Cordless Power Tool Charger Controller 686 £6.18 20W Class-A Amplifier Module – Left Channel 687 £7.29 EPE PRINTED CIRCUIT BOARD SERVICE – Right Channel 688 £7.29 Order Code Project Quantity Price – PSU 689 £6.50 NOVEMBER ’08 ...... , 50MHz Frequency Meter – Mk. 2 – Version 1 581 £6.66 Name ...... – Version 2 582 £6.66 – Version 3 583 £6.66 Address ...... Variable Turbo Boost Control 690 set £6.34 ...... Fuel Cut Defeater 691 DECEMBER ’08 Tel. No...... , Christmas Star 692 £6.97 I enclose payment of £ ...... (cheque/PO in £ sterling only) to: 20W Class-A Amplifier – Speaker Protector & Muting 693 £6.66 Radar Speed Gun – Head 694 set £14.95 – Display 695 Everyday Practical JANUARY ’09 Electronics 20W Class-A Amplifier – Preamplifier and Remote Volume Control 696 £7.93 1000:1 UHF Prescaler (double sided) 697 £12.05 Card No...... FEBRUARY ’09 1.3V To 22V Regulated Power Supply 698 £5.39 Valid From ...... Expiry Date ......
, LED Tachometer – Control Board 699 Card Security No...... Maestro Issue No...... set £9.52 – Display Board 700 MARCH ’09 Signature ...... Tank Water Level Indicator 701 £6.34 Note: You can also order PCBs by phone, Fax or Email or via the , Digital Stereo VU/Peak Meter – Main Board 702 set £8.24 Shop on our website on a secure server: – Switch Board 703 http://www.epemag.com
78 Everyday Practical Electronics, August 2009 CLASSIFIED ADVERTISEMENTS
If you want your advertisements to be seen by the largest readership at the most economical price our classified page offers excellent value. The rate for semi-display space is £10 (+VAT) per centimetre high, with a minimum height of 2·5cm. All semi-display adverts have a width of 5.5cm. The prepaid rate for classified adverts is 40p (+VAT) per word (minimum 12 words). All cheques, postal orders, etc., to be made payable to Everyday Practical Electronics. VAT must be added. Advertisements, together with remittance, should be sent to Everyday Practical Electronics Advertisements, Sequoia House, Everyday Practical Electronics reaches more UK readers than any other 398a Ringwood Road, Ferndown, Dorset BH22 9AU. Phone: 01202 873872. UK monthly hobby electronics magazine, our sales figures prove it. We have been the leading monthly magazine in this market for the last Fax: 01202 874562. Email: [email protected]. For rates and information twenty-three years. on display and classified advertising please contact our Advertisement Manager, Stewart Kearn as above.
BTEC ELECTRONICS The British TECHNICIAN TRAINING Amateur NATIONAL ELECTRONICS Electronics Club VCE ADVANCED ICT HNC AND HND ELECTRONICS Archive Website. Archiving extracts for 140+ Newsletters from FOUNDATION DEGREES 1966-2002. Currently have NVQ ENGINEERING AND IT interesting and useful selected articles from 19 DESIGN AND TECHNOLOGY Newsletters. LONDON ELECTRONICS COLLEGE Also a section about built electronics projects with schematics and photos. 20 PENYWERN ROAD Plus useful info., downloads and links. EARLS COURT, LONDON SW5 9SU “NO ADVERTS!” TEL: (020) 7373 8721 Website Address: http://baec.tripod.com www.lec.org.uk www.cstech.co.uk www.partridgeelectronics.co.uk 28 & 40 pin USB For The Electronic Components & PIC Hardware You Have Been Prototyping Kits www.apdanglia.org.uk Looking For From £12.99 For RFID Components EM4100 Cards .99p - Keyfobs £1.09 T5557 keyfobs £1.65 inc vat plus RFID Coils, BOWOOD ELECTRONICS LTD CANTERBURY WINDINGS 125 khz R/W modules - RFID RS232 PCB’s, Suppliers of Electronic Components UK manufacturer of toroidal transformers RFID IC’s EM4095 - U2270B- Prox keypads Place a secure order on our website or call our sales line (10VA to 1kVA) Technical information pages All major credit cards accepted All transformers made to order. No design fees. Web: www.bowood-electronics.co.uk No minimum order. Visit our website for further details Unit 10, Boythorpe Business Park, Dock Walk, Chesterfield, No min order charge - UK Delivery £2.50 Derbyshire S40 2QR. Sales: 01246 200222 www.canterburywindings.co.uk Send 60p stamp for catalogue 01227 450810 Miscellaneous VALVES AND ALLIED COMPONENTS IN STOCK. Phone for free list. Valves, books and magazines wanted. Geoff Davies ! " # (Radio), tel. 01788 574774.
$ % $ & !()* + , !() - . / 0 . " 1·0, 2·5 + 30·0 RPM MAINS MOTORS 240V 4W. Body 50mm diameter × 25mm with lugs. Shaft 7mm diameter. £9.85 includ- ing postage. C. Brittain, 12 Marina Drive, Wolverton, MK12 5DW. 07986 824998 ELECTRONICS TEACH-IN BY MIKE TOOLEY plusp FREE CD-ROM INCLUDING P&P FROM OUR ONLY £8.50 DIRECT BOOK SERVICE A broad-basedbroad based introductionintroduction toto electronicselectronics – find out how circuits work and what goes on inside them. Plus 15 easy-to-build projects. The 152 page A4 book comes with a free CD-ROM containing the whole Teach-In 2006 series (originally published in EPE) in PDF form, interactive quizzes to test your knowledge, TINA citcuit simulation software (a limited version – plus a specially written TINA Tutorial), together with simulations of the circuits in the Teach-In series, plus Flowcode (a limited version) a high level programming system for PIC microcontrollers based on flowcharts. See our Direct Book Service – pages 75 to 77
EverydayEveryday Practical Electronics, AugustAugus 2009 79 R NEXT MONTH Established for over 25 years, UK company KEYLESS ENTRY SYSTEM – PART 2 Display Electronics prides itself on offering a Following on from last month’s electronic introduction to this super secure door entry system, Part 2 covers installation and setting-up massive range of electronic and associated procedures. Plus, we will explain how to include an optional SOIC electro-mechanical equipment and parts to adaptor board to enable PIC programming. the Hobbyist, Educational and Industrial PIC PROGRAMMER SOIC CONVERTER user. Many current and obsolete hard to get Surface-mount PIC chips are great for building tiny smart circuits, parts are available from our vast stocks, but when its time for programming, how do you access the pins? The answer is our 18-lead surface-mount PIC Programmer SOIC which include: * Converter. This adaptor PC board accepts these handy devices , 6,000,000 Semiconductors and plugs directly into a conventional PIC programmer. , 5,000 Power Supplies PROGRAMMABLE IGNITION – PART 1 , Want to program the ignition timing on your car? Now you can, with 25,000 Electric Motors , this completely new design. It can even be used in older cars that 10,000 Connectors don’t have electronic ignition or used as an ‘interceptor’ for cars , 100,000 Relays & Contactors with engine management systems. Your spark plugs will thank you. , 2000 Rack Cabinets & Accessories RECYCLE IT! – DRILLER THRILLER , 4000 Items of Test Equipment Cordless drills are probably the most frequently discarded power , 5000 Hard Disk Drives tools. Rubbish to some, but a wealth of opportunity for EPE readers! Don’t miss next month’s recycling top tips for making the ! most of cheap-as-chips high quality components. " )* SEPTEMBER ’09 ISSUE # $ %& ' ( ON SALE 13 AUGUST )* + * 2334 05&% %%%% ,- .(/ 01" 6 7 2334 05&% 0000 Content may be subject to change
Rechargeable Batteries With Solder Tags NIMH NICAD ADVERTISERS INDEX AA 2000mAh ...... £2.82 AA 650mAh...... £1.41 C 4Ah ...... £4.70 C 2.5Ah ...... £3.60 BETA LAYOUT ...... 67 D 9Ah ...... £7.60 D 4Ah ...... £4.95 PP3 150mAh ...... £4.95 CRICKLEWOOD ...... 21
Instrument case with edge connector and screw terminals DISPLAY ELECTRONICS ...... 80
Size 112mm x 52mm x 105mm tall ESR ELECTRONIC COMPONENTS ...... 6, Cover (iii)
This box consists of a cream base with a PCB slot, a cover plate to pro- JAYCAR ELECTRONICS ...... 4/5 tect your circuit, a black lid with a 12 way edge connector and 12 screw terminals built in (8mm pitch) and 2 screws to hold the lid on. The cream JPG ELECTRONICS ...... 80 bases have minor marks from dust and handling price £2.00 + VAT(=£2.35) for a sample or £44.00+VAT (=£51.70) for a box of 44. LABCENTER ...... Cover (iv) LASER BUSINESS SYSTEMS ...... 67 MAGENTA ELECTRONICS ...... 67 NURVE NETWORKS LLC ...... 63 PEAK ELECTRONIC DESIGN ...... Cover (ii) PICO TECHNOLOGY...... 21 QUASAR ELECTRONICS ...... 2/3 866 battery pack originally intended to be used with an orbitel mobile telephone it SHERWOOD ELECTRONICS ...... 21 contains 10 1·6Ah sub C batteries (42 x 22 dia. the size usually used in cordless STEWART OF READING...... Cover (ii) screwdrivers etc.) the pack is new and unused and can be broken open quite easily £7.46 + VAT = £8.77 ADVERTISEMENT OFFICES: Please add £1.66 + VAT = £1.95 postage & packing per order JPG Electronics Sequoia House, 398a Ringwood Road, Ferndown, Dorset BH22 9AU Shaws Row, Old Road, Chesterfield, S40 2RB. PHONE: 01202 873872 Fax: 01202 874562 Tel 01246 211202 Fax 01246 550959 EMAIL: [email protected] www.JPGElectronics.com Mastercard/Visa/Switch Callers welcome 9.30 a.m. to 5.30 p.m. Monday to Saturday For Editorial address and phone numbers see page 7
Published on approximately the second Thursday of each month by Wimborne Publishing Ltd., Sequoiaquoia House, 398a Ringwood Road, Ferndown,Ferndown, Dorset BH22 9AU. Printed in England by Acorn Web Offset Ltd., Normanton, WF6 1TW. Distributed by Seymour, 86 Newman St., London W1T 3EX. Subscriptions INLAND: £19.95 (6 months); £37.90 (12 months); £70.50 (2 years). OVERSEAS: standard air service, £23.00 (6 months); £44.00 (12 months); £83.00 (2 years). Express airmail, £32.00 (6 months); £62.00 (12 months); £119.00 (2 years). Payments payable to “Everyday Practical Electronics’’, Subs Dept, Wimborne Publishing Ltd. Email: [email protected]. EVERYDAY PRACTICAL ELECTRONICS is sold subject to the following conditions, namely that it shall not, without the written consent of the Publishers first having been given, be lent, resold, hired out or otherwise disposed of by way of Trade at more than the recommended selling price shown on the cover, and that it shall not be lent, resold, hired out or otherwise disposed of in a mutilated condition or in any unauthorised cover by way of Trade or affixed to or as part of any publication or advertising, literary or pictorial matter whatsoever. TheT UK’s number 1 source of VELLEMAN® products.. WeW are the only current UK supplier aableb to offer the full range of VellemanV - Mini Kits - Kits - Modules & Test Equipment. All the latest prpproducts added as released. Audio Amplifier RGB LED Controller PIC Programmer 2 x 15Wrms (4 ohm) or 2 x 10Wrms Ideal for LED strips, also suitable Suitable for a wide range (8 ohm). Overheating & short cir- for incandescent lamps. Wide of Microchip® PIC™ mi- cuit protected. No need for rectifi- range of effects. Hi-power crocontrollers, onboard er & smoothing, only AC supply MOSFETs 3A per channel, configurable 40 pin. ZIF required. 10-15Vdc supply. socket, Microcontroller se- K4003 Kit £17.84 lection using patch jumper, VM113 Assembled £19.99 K8088 RGB LED Controller Kit £15.15 easy to use programming VM146 Assembled version £22.52 Audio Amplifier PICprog2006™ software VM151 Assembled version with remote control £29.53 100Wrms @ 4ohm DC sup- included, SUBD connector set included. ply circuit on board with Pocket Audio Generator K8076 Kit £24.95 LED indication ideal for Microprocessor Technology Digitall PIC Programmer active speaker system or waveform audio generator. For Microchip® FLASH PIC™ subwoofer, guitar amp, 50Hz, 100Hz, 1kHz, 10kHz & 20kHzHz microcontrollers supports 4 home theatre systems, etc. different 300 mil. PICs: 8p, Overload & short-circuit protected. K8065 Kit £13.4141 14p, 18p and 28p test buttons K8060 Kit £14.18 VM156 Assembled £20.0000 and LED indicators. Supplied with programming examples 171-030 Heatsink for above £11.18 High Power LED Driver & easy connection to a PC VM100 Assembled with heatsink £38.54 Power up to four 1W or two 3W high-power LEDs (not through the serial port. Supplied with a PIC16F627 and 325-030 120VA Toroidal Transformer £14.25 incl.) Delivers accurate constant current required by most software to compile and program your source code. Audio Amplifier high-power LEDs, built-in rectifier for easy K8048 Kit £25.38 Stereo 2 x 50Wrms or a connection to AC source, compact size, VM111 Assembled £36.20 Mono 100Wrms ampli- short-circuit protected, no heatsink re- fier. Three input quired. USB Interface sensitivity settings. K8071 Kit £5.86 A interface board with 5 digital Overload & short-cir- VM143/1W for 1W LEDs £10.52 input & 8 digital output chan- cuit protection, protection against incorrect power supply VM143/3W for 3W LEDs £11.07 nels. In addition, there are two polarity. Speaker transient suppression.ion. analogue inputs & two ana- 3-30V 3A Power Supply K4004 Kit £54.88 logue outputs with 8 bit resolu- Suitable as a power supply for all tion. All communication routines are contained in a High-End Control Amplifier common Velleman kits using a Dynamic Link Library (DLL). You may write custom Win- 4 Input, inc RIAA input stabilised DC voltage between 3 dows (98SE, 2000, Me, XP) applications in Delphi, Visual Headphone output and 30V, 3A max. Of course this Basic, C++ Builder or any other 32-bit Windows applica- Audio Grade OpAmps power supply unit can also be tion development tool that supports calls to a DLL. Capacitor-less Coupling used for other purposes. By replacing the trimmer by a K8055 Kit £25.65 Including Solid Aluminium Housing potentiometer, it may even be used as an adjustable VM110 Assembled £38.78 power supply unit. Supplied with heat sink. K8021 Kit £155.37 K7203 Kit £25.10 USB Interface Board With a total of 33 Sub-Woofer Amplifier 1A Power Supply input/outputs: including ana- Bass-reflex system with Low cost universal symmetric power supply just add a logue / digital and + 1PWM adjustable tube. Complete suitable transformer and a heatsink, output. Connection to the kit (exc wood panels) to builduild ... trimmers can be replaced by po- computer is galvanically op- a 100W compact active tentiometers to allow continuous ad- tically isolated, so that dam- sub-woofer. 25-100Hz justment of output, LED output age to the computer is not indicators. possible thus providing a high level of secure implementa- K8077 Kit £85.80 K8042 Kit £7.78 tion. Supplied with test software & examples. K8061 Kit £66.48 VM140 Assembled £83.15 We also carry the Velleman range of fully assembled test equipment. This range of hand held Scopes and PC based Mini PIC Application Module measurement equipment, uses all the latest techniques to achieve "state of the art" equipment that would be at home Create your own custom PIC in any industrial applicationsions or in the hahands of the enthusiast. Full specs on our web site. application without the hassle of making the hardware. USBU Scope & Function Generator 9 Free programmable I/Os. A cocompletemplep te U USBSB powered lab in a box. Feature-packed PcLab2000-LTPcLab2000-LT softwares for two channel oscilloscope, Onboard Relay, LEDs & Buzz- spectrum analyser, recorder, function generator and er. PIC16F630 inc. bode plotter. VM142 Assembled £26.000
PCSGU250 USB Scope & Function gen. £113.67 USB DMX Interface Control DMX fixtures using a PC and USB interface, test software and "DMX Light Player" software is included, a Two channel USB PC Oscilloscope Handheld Oscilloscope DLL is provided to write your own A digital storage oscilloscope uses the •40MHz Sampling rate • 12Mhz Analogue software. Stand-alone test func- power of your PC to visualize electrical bandwidth • High resolution LCD with tion that outputs all 512 channels signals. Its high sensitive display resolu- Backlight • Data recorder function •RS232 at a time, with adjustable levels. tion, down to 0.15mV, combined with a PC Link Supplied with case, lead & high bandwidth and a sampling fre- Supplied with Probe, Carry CDROM quency of up to 1GHz are giving this case & Leads. K8062 Kit £55.55 unit all the power you need. VM116 Assembled £69.64
PCSU1000 USB PC Scope & Probes £316.64 HPS40 Handheld Scope £257.06 Record/Playback Kit 10 to 35 second recordord timetime 2MHz USB PC Function Generator ..... other Velleman Instruments High Quality Audio A digital function generator which can be APS230 Advanced Personal Scope £385.000 Amplifier & Speakerr IncludedIncluded connected with a PC via USB. Standard HSP10 Handheld Scope £115.144 Separate Line outputt signal waves like sine, triangle and rec- Handheld Scope inc case £128.222 HSP10SE External Trigger tangle are available; other sine waves HPS50 Handheld USB Scope £257.45 Speed Control can be easily created. The signal waves PCS500A PC Digital Storage Scope £317.466 4.5Vdc Supply are created in the PC and produced by PPS10 Personel Poscket Scope £115.133 1μA Standby the function generator via DDS (Direct VPS10 Panel Scope £115.533 Digital wave Systhesis). PCS10 4 Channel Data Logger £32.68 MK174 Mini Kit ££11.8711.87 PCGU1000 USB Function Generator £118.38 see our web site for full specifications
PricesPrices Exclude Vat @@15%.15%. 05/09 StationStStaatatiotion RRoRoadoaoadad Tel:TeTel:l: 019101019191 2514363252514343636363 UKU Carriageg £2.50 ((less than 1kg)g) CullercoatsCuCulullelerercocoaoatatss £5.50 greatergreater tthanhan 11kgkgg or >£30 Fax:FaFaxax:x: 019101019191 252229625252522222929696 TyneTyTynynene & WeWWearearar ChequesC q / Postal orders pypayable to www.esr.co.ukwwwwwww.ew.w.eesesrsr.cr.r.c.ccoo.uk [email protected]@[email protected] NENNE30E3E3030 4P44PQPQPQ ESR ElectronicElectronic Components Ltd.Ltd. PLEASEPLEASE ADDADD CACARRIAGERRIAGE & VVATAT TTOO AALLLL OORDERSRDERS
The UK’s number 1 source of VELLEMAN® products.. We are the only current UK supplier able to offer the full range of Velleman - Mini Kits - Kits - Modules & Test Equipment. All the latest products added as released. Audio Amplifier RGB LED Controller PIC Programmer 2 x 15Wrms (4 ohm) or 2 x 10Wrms Ideal for LED strips, also suitable Suitable for a wide range (8 ohm). Overheating & short cir- for incandescent lamps. Wide of Microchip® PIC™ mi- cuit protected. No need for rectifi- range of effects. Hi-power crocontrollers, onboard er & smoothing, only AC supply MOSFETs 3A per channel, configurable 40 pin. ZIF required. 10-15Vdc supply. socket, Microcontroller se- K4003 Kit £17.84 lection using patch jumper, VM113 Assembled £19.99 K8088 RGB LED Controller Kit £15.15 easy to use programming VM146 Assembled version £22.52 Audio Amplifier PICprog2006™ software VM151 Assembled version with remote control £29.53 100Wrms @ 4ohm DC sup- included, SUBD connector set included. ply circuit on board with Pocket Audio Generator K8076 Kit £24.95 LED indication ideal for Microprocessor Technology Digital PIC Programmer active speaker system or waveform audio generator. For Microchip® FLASH PIC™ subwoofer, guitar amp, 50Hz, 100Hz, 1kHz, 10kHz & 20kHz microcontrollers supports 4 home theatre systems, etc. different 300 mil. PICs: 8p, Overload & short-circuit protected. K8065 Kit £13.41 14p, 18p and 28p test buttons K8060 Kit £14.18 VM156 Assembled £20.00 and LED indicators. Supplied with programming examples 171-030 Heatsink for above £11.18 High Power LED Driver & easy connection to a PC VM100 Assembled with heatsink £38.54 Power up to four 1W or two 3W high-power LEDs (not through the serial port. Supplied with a PIC16F627 and 325-030 120VA Toroidal Transformer £14.25 incl.) Delivers accurate constant current required by most software to compile and program your source code. Audio Amplifier high-power LEDs, built-in rectifier for easy K8048 Kit £25.38 Stereo 2 x 50Wrms or a connection to AC source, compact size, VM111 Assembled £36.20 Mono 100Wrms ampli- short-circuit protected, no heatsink re- fier. Three input quired. USB Interface sensitivity settings. K8071 Kit £5.86 A interface board with 5 digital Overload & short-cir- VM143/1W for 1W LEDs £10.52 input & 8 digital output chan- cuit protection, protection against incorrect power supply VM143/3W for 3W LEDs £11.07 nels. In addition, there are two polarity. Speaker transient suppression. analogue inputs & two ana- 3-30V 3A Power Supply K4004 Kit £54.88 logue outputs with 8 bit resolu- Suitable as a power supply for all tion. All communication routines are contained in a High-End Control Amplifier common Velleman kits using a Dynamic Link Library (DLL). You may write custom Win- 4 Input, inc RIAA input stabilised DC voltage between 3 dows (98SE, 2000, Me, XP) applications in Delphi, Visual Headphone output and 30V, 3A max. Of course this Basic, C++ Builder or any other 32-bit Windows applica- Audio Grade OpAmps power supply unit can also be tion development tool that supports calls to a DLL. Capacitor-less Coupling used for other purposes. By replacing the trimmer by a K8055 Kit £25.65 Including Solid Aluminium Housing potentiometer, it may even be used as an adjustable VM110 Assembled £38.78 power supply unit. Supplied with heat sink. K8021 Kit £155.37 K7203 Kit £25.10 USB Interface Board With a total of 33 Sub-Woofer Amplifier 1A Power Supply input/outputs: including ana- Bass-reflex system with Low cost universal symmetric power supply just add a logue / digital and + 1PWM adjustable tube. Complete suitable transformer and a heatsink, output. Connection to the kit (exc wood panels) to build ... trimmers can be replaced by po- computer is galvanically op- a 100W compact active tentiometers to allow continuous ad- tically isolated, so that dam- sub-woofer. 25-100Hz justment of output, LED output age to the computer is not indicators. possible thus providing a high level of secure implementa- K8077 Kit £85.80 K8042 Kit £7.78 tion. Supplied with test software & examples. K8061 Kit £66.48 VM140 Assembled £83.15 We also carry the Velleman range of fully assembled test equipment. This range of hand held Scopes and PC based Mini PIC Application Module measurement equipment, uses all the latest techniques to achieve "state of the art" equipment that would be at home Create your own custom PIC in any industrial applications or in the hands of the enthusiast. Full specs on our web site. application without the hassle of making the hardware. USB Scope & Function Generator 9 Free programmable I/Os. A complete USB powered lab in a box. Feature-packed PcLab2000-LT software for two channel oscilloscope, Onboard Relay, LEDs & Buzz- spectrum analyser, recorder, function generator and er. PIC16F630 inc. bode plotter. VM142 Assembled £26.00
PCSGU250 USB Scope & Function gen. £113.67 USB DMX Interface Control DMX fixtures using a PC and USB interface, test software and "DMX Light Player" software is included, a Two channel USB PC Oscilloscope Handheld Oscilloscope DLL is provided to write your own A digital storage oscilloscope uses the •40MHz Sampling rate • 12Mhz Analogue software. Stand-alone test func- power of your PC to visualize electrical bandwidth • High resolution LCD with tion that outputs all 512 channels signals. Its high sensitive display resolu- Backlight • Data recorder function •RS232 at a time, with adjustable levels. tion, down to 0.15mV, combined with a PC Link Supplied with case, lead & high bandwidth and a sampling fre- Supplied with Probe, Carry CDROM quency of up to 1GHz are giving this case & Leads. K8062 Kit £55.55 unit all the power you need. VM116 Assembled £69.64
PCSU1000 USB PC Scope & Probes £316.64 HPS40 Handheld Scope £257.06 Record/Playback Kit 10 to 35 second record time 2MHz USB PC Function Generator ..... other Velleman Instruments High Quality Audio A digital function generator which can be APS230 Advanced Personal Scope £385.00 Amplifier & Speaker Included connected with a PC via USB. Standard HSP10 Handheld Scope £115.14 Separate Line output signal waves like sine, triangle and rec- Handheld Scope inc case £128.22 HSP10SE External Trigger tangle are available; other sine waves HPS50 Handheld USB Scope £257.45 Speed Control can be easily created. The signal waves PCS500A PC Digital Storage Scope £317.46 4.5Vdc Supply are created in the PC and produced by PPS10 Personel Poscket Scope £115.13 1μA Standby the function generator via DDS (Direct VPS10 Panel Scope £115.53 Digital wave Systhesis). PCS10 4 Channel Data Logger £32.68 MK174 Mini Kit £11.87 PCGU1000 USB Function Generator £118.38 see our web site for full specifications
Prices Exclude Vat @15%. 05/09 Station Road Tel: 0191 2514363 UK Carriage £2.50 (less than 1kg) Cullercoats £5.50 greater than 1kg or >£30 Fax: 0191 2522296 Tyne & Wear Cheques / Postal orders payable to www.esr.co.uk [email protected] NE30 4PQ ESR Electronic Components Ltd. PLEASE ADD CARRIAGE & VAT TO ALL ORDERS LEAP INTO THE FUTURE...
Powerful EDA Software at Affordable Prices PROTEUS DESIGN SUITE Features:
nEasy to use, standard Windows interface. nAutomatic component placement
nPublication quality schematics. and gateswap optimization.
nFully configurable bill of materials. nHighly configurable design rules.
nLarge component libraries for both nInteractive design rule checking. simulation and PCB layout. nPolygonal and split power planes.
nMixed mode SPICE circuit simulation. nWorld class shape based autorouter.
nCo-simulation of PIC, AVR, 8051 and nAutomatic mitre/unmitre commands. ARM7 microcontroller firmware. nIndustry standard CADCAM & ODB++ output.
nIntegrates with MP-LAB and AVR Studio. nIntegrated 3D Viewer with 3DS and DXF export.
All levels of the Proteus Design Suite now include a world class fully integrated shape based autorouter at no additional cost - prices start from just £150 exc. VAT & delivery
Visit our website or phone 01756 753440 Labcenter Electronics Ltd. 53-55 Main Street, Grassington, North Yorks. BD23 5AA. Registered in England 4692454 Tel: +44 (0)1756 753440, Email: [email protected] for more details