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1. August 2008 b Everyday Practical Electronics 16 Constructional into matching holes in the connec tor bodies so the operation is quite straightforward The five single RCA sockets CON1 to CONS can then be fitted to the panel above the mini DIN sockets with the supplied earthing solder lugs under the nuts and oriented upwards Tighten each nut using a small span ner or pliers then bend the free part of the lug forwards by about 75 Finally solder the yellow wires to the centre terminals of the sockets and the black wires to the earth lugs Front panel The front panel assembly is even easier just mount the four push button switches S1 to S4 but don t over tighten the large plastic nuts provided as it s easy to strip their threads if too much force is ap plied Note that each switch should be positioned so that its terminals are aligned horizontally for easy connection of the wires from the PC board That done lower the front panel into its slot in the bottom of the box and solder the switch leads to their matching wires A word of warn ing here make each solder joint as quickly as possible so that you don t overheat the switch or risk melting the solder at the lower end of each wire Finally push the green power LED LED5 through its matching hole and install the four channel indicator LEDs LEDs 1 to 4 The latter are simply pushed through their respective f
2. em FOU n 1o00 and commaosita maaa De GU SIRE RT cu B acer RED dm emm car applications Ri o 74470 07806 Ce LES AUDIO SOLUTIONS POWER SUPPLY CONTROLLER CHIP ALFET LATERAL MOSFETS __ CUSTOM DESIGN PCB Fe POWER AMP MODULES POWER SUPPLY MODULES PROFESSIONAL SPEAKER SYSTEMS BESPOKE LOUDSPEAKER CABINET DESIGN OEM POWER AMP DESIGN amp MANUS CUSTOM HEATSINKS pov Bs vn meon DI a DEUM T m r EE NN Fora list of our products go to our sites www class d com or www poweramplifiers itd uk Contact us on 01623 654080 or 07980 600 373 Email sales class d com or garry class d com ISSN 0262 3617 PROJECTS THEORY NEWS COMMENT e e POPULAR FEATURES 9 VOL 37 No 8 August 2008 Wimborne Publishing Ltd 2008 Copyright in all drawings photographs and articles published in EVERYDAY PRACTICAL ELECTRONICS is fully protected and reproduction or imitations in whole or in part are expressly forbidden Our September 2008 issue will be published on Thursday 14 August 2008 see page 72 for details Everyday Practical Electronics August 2008 INCORPORATING ELECTRONICS TODAY INTERNATIONAL www epemag co uk EPE Online www epemag com FOUR CHANNEL A V SELECTOR by Jim Rowe Select one of four S video or composite video sources plus audio DC RELAY SWITCH by
3. Fig 2 A switch using a BJT bipolar junction transistor in common emitter configuration Current gain Animportant characteristic of the transistor in the forward active region is the current gain or strictly speaking the forward current gain This is the familiar transistor gain and has the symbol f 6 or hj In the forward active region the collector and base currents are related by the well known relationships I fI and I 1 f These are simple and useful equations but they do not apply in the saturation region For a transistor in saturation the base current is greater than I B In fact the base current exceeding I B can be regarded as a condition for saturation The value of I I in saturation is called the forced beta Pror An example will hopefully clarify how we make use of these ideas Let s say we want to use the circuit in Fig 2 to supply 100mA to the load resistor R using a suitable transistor in terms of current rating Assume the transistor has a typical gain of 100 ie 6 100 and that the supply is 5V We might proceed as follows If we assume a very small collector emitter voltage and ignore this then there is 5V across the resistor To limit the current to 100mA in this situation we need a resistor value of 50Q R V I 5 0 1 If we use I I we get I 0 1 100 ImA If we assume that V is 0 7V to get ImA base current we need R V I 5 0 7 0 001 4 3kQ
4. FireFly radio remote control systems provide security and versatility RF Solutions has launched a new remote control system housed in a rugged IP68 weatherproof enclosure Delivering a transmitting range of up to 100 metres the general purpose FireFly module can be used in a variety of applications including lighting control remote switching industrial remote switching and access control Each individual switch on each of the transmitters may be paired with any or all of the receiver relay outputs The receiver has the capacity to learn up to 15 transmitter button pairings which are remembered even if the power is removed Installation simply requires connections to power supply and the output relay screw terminals The output relays are activated by the button press on the transmitter encoder The decoder is supplied in an IP68 rated enclosure with cable gland and wall mounting lugs This FireFly unit is designed to be a fixed installation operated from either 12 24V DC or 230V AC Each FireFly transmitter has a unique identity Every time a switch is pressed the transmitter emits a highly secure RF signal which appears as a random encrypted data stream The receiver can learn this encrypted signal and allocate it to an output Any transmitter switch may be paired to one or many of the receiver s outputs or a transmitter single switch may be paired to any number of receiver s outputs to enable a
5. explained along with tutorials on soldering iron and multimeter controller is 12 volt DC powered and can also be used in makes an ideal automotive applications inexpensive e Kit supplied with silk beginners kit screened e PC board size E D use All projects are PCB and 45 x 22mm safe and battery processed powered panels Softcover full colour 205 x 275mm Short Circuits Volume Ill Universal Speaker Protection BJ 8505 7 99 post amp packing Voltage Monitor Kit 8 This is the definitive electronics training manual and an d Mu ti ng Modul e Kit KC 5424 6 00 post amp packing presents more than 30 individual printed circuit board KC 5450 8 75 post amp packing This versatile kit will allow you to monitor the battery based construction Protects your expensive speakers against damage in the voltage the airflow meter or oxygen sensor in your vehicle projects Each project event of catastrophic amplifier failure such as a shorted The kit features 10 LEDs that light up in response to the contains a full output transistor In addition the circuit also banishes measured voltage preset 9 16V 0 5V or 0 1V ranges technical description those annoying thumps that occur when many amplifiers complete with a fast response time high input impedance with experimental are switched on or off especially when the volume is set and auto dimming for night driving Kit changes to each circuit to a high level The des
6. A e selection of high Thyristor Relay Op Amp Modules Logic Modules 555 Timer PIC PICAXE Output Devices Transistor Drivers Relay Motor Direction amp Speed Control 7 Segment Displays Data sections with pinouts etc Example Projects Full Search Facility Further Background Information and Animated Diagrams Runs in Microsoft Internet Explorer All circuits can be viewed but can only be simulated if your computer has Crocodile Technoloy version 410 or later A free trial version of Crocodile Technology can be downloaded from www crocodile clips com Animated diagrams run without Crocodile Technology resolution photos can be used to enhance projects and presentations or to help with training and educational material They are royalty free for use in commercial or personal printed projects and can also be used royalty free 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 17 596 to plus VAT prices Also contains a FREE 30 day evaluation of Paint Shop Pro 6 Paint Shop Pro image Minimum system requirements for these CD ROMs Pentium PC CD ROM drive 32MB RAM 10MB hard disk editing tips and on line help included space Windows 95 98 NT 2000 ME XP mouse sound card web b
7. 26 95 PC Interface Board This interface card excels in its simplicity of use and installa tion The card is con nected in a very sim ple way to the printer port there is no need to open up the computer Likewise there is no need to install an extra printer port even if a printer is to be used This can be connected to the card in the usual manner Connection to the computer is optically isolated so that damage to the computer from the card is not possible Kit Order Code VK8000KT 59 95 ost items are available in kit form KT suffix r assembled and ready for use AS prefix Motor Speed Controllers Here are just a few of our controller and driver modules for AC DC Unipolar Bipolar stepper motors and servo motors See website for full details DC Motor Speed Controller 100V 7 5A Control the speed of almost any common DC motor rated up to 100V 7 5A Pulse width modulation output for maximum motor torque at all speeds Supply 5 15Vdc Box supplied Dimensions mm 60Wx100Lx60H Kit Order Code 3067KT 13 95 Assembled Order Code AS3067 21 95 PC Standalone Unipolar Stepper Motor Driver Drives any 5 6 or 8 lead unipolar stepper motor rated up to 6 Amps max Provides speed and direc i tion control Operates in stand alone or PC controlled mode Up to six 3179 driver boards can be connected to a single parallel port Supply 9Vdc PCB 80x50mm Kit Order Code 3179
8. Private Sub MSComm1_OnComm If MSComml CommEvent 2 Then SerData MSComml Input Labell Caption Asc SerData End If End Sub There are two basic approaches to reading serial data one of which is called polling This method involves frequent checking of the serial interface to determine whether any fresh data is available While Seles polling works well it is very inefficient because it results in a great deal of wasted processing time while the serial interface is checked for non existent data The alternative method and the one used here is the event method This is much more efficient and it generates an OnComm event when a certain number of bytes have been received The program then responds to this event and processes the data The number of bytes needed to trigger an OnComm event is controlled by the RThreshold parameter and in this case a value of 1 is used so that the bytes are read one by one The InputLen setting will normally have the same value as RThreshold and it determines the number of bytes that will be read from the receiver buffer each time the program fetches serial data This program uses an If Then loop to read the received data and it loops until Comm Event returns a value of 2 which occurs when the appropriate number of bytes are ready to be processed Of course in this case a value of 2 is returned each time a new byte of data is received There are actually seven types of C
9. The problem with this is that transistor gain is actually quite variable under different conditions current temperature and importantly between individual transistors So our assumption that the gain is 100 is likely to be wrong If the gain was actually only 70 we would only get approximately 70mA through the load far less than we expected The assumption that collector emitter voltage is very small would also be wrong it would actually be about 1 5V Now let s look at the same circuit gain but this time making sure the transistor is in saturation Unlike the actual beta we can choose a forced beta let s say ten times smaller than the nominal value that is 6 I 10 So with all else the same as above we need a base current of 10mA for which R V I 5 0 7 0 01 4309 Note that this value is similar to the one used for R2a R2b etc in Fig 1 Now if our transistor gain is 70 rather than 100 we still get 10mA in the base and 100mA through the LED and a small collector emitter voltage The forced beta is only seven times less than the actual beta rather than ten times as we designed but the factor of ten has given us plenty of margin for error in making sure the transistor is saturated If we change the load resistance in the circuit in Fig 2 for example we halve or double R the transistor remains in saturation The voltage across the load therefore remains almost constant with a large load
10. 6 months 19 95 12 months 37 90 two years 70 50 Overseas 6 months 23 00 standard air service or 32 00 express airmail 12 months 44 00 standard air service or 62 00 express airmail 24 months 83 00 standard air service or 119 00 express airmail Online subscriptions for downloading the magazine via the Internet 18 99US approx 9 50 for one year available from www epemag com Cheques or bank drafts in sterling only payable to Everyday Practical Electronics and sent to EPE Subs Dept Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Tel 01202 873872 Fax 01202 874562 Email subs epemag wimborne co uk Also via the Web at http www epemag wimborne co uk Subscriptions start with the next available issue We accept MasterCard Maestro or Visa For past issues see the Back Issues page BINDERS Binders to hold one volume 12 issues are available from the above address These are finished in blue PVC printed with the magazine logo in gold on the spine Price 7 95 plus 3 50 p amp p for overseas readers the postage is 6 00 to everywhere except Australia and Papua New Guinea which cost 10 50 Normally sent within seven days but please allow 28 days for delivery more for overseas Payment in sterling only please Visa Maestro and MasterCard accepted Send fax or phone your card number card expiry date valid from date and card security code the
11. 01202 873872 toes M Quote Advertising and Business Manager o ChAMTY hel schools STEWART KEARN 01202 873872 j d Sew hem to MAP vod On line Editor ALAN WINSTANLEY zenith developing EPE Online Internet version Editors poawisatt CO gata d uc I CLIVE Max MAXFIELD and ALVIN BROWN diss 0 ve and cond t se Publisher MIKE KENWARD sta i Los dag eX tho ynote i x those muck De they also up 7 nehines use V gau Cheap ae Miexosott 0 eQ tO i onnassed a techno hoo hon perros pur Vicon GMO sending it eX Q SU Ware TW idges QW y need sons pinte a livery tO owitolo e bes WW M 5 M ok cat T does m TO o al useless e that you te Q clas Coe helping to eduta els do t Nike 1e Jm E oV a S EV at their 009 SUBSCRIPTIONS AVAILABILITY Copies of EPE are available on subscription anywhere in the world see opposite and from all UK newsagents distributed by SEYMOUR EPE can also be purchased from retail magazine outlets around the world An Internet online version can be purchased and downloaded for just 18 99US approx 9 50 per year available from www epemag com oP 2A Fr e Fed TLECTRONICS Sad A L WWW ene nag co uk D j i PICIMIDIIWAVE SOUND GENERA hl S p Vf 7 ji Ai horis RB GALA GMI CIVOIGI MESSI A es SE euina ALIUS Constnuctionjand luXeons pO wenedis poti ig h uu ee gs www en en ag com Subscriptions for delivery direct to any address in the UK
12. Example of the PC Recall screen displaying a file s waveform EBX 1145 having a transmitter and receiver module on each board Handshaking was then used with the PC transmitting the ID of the module it wanted to send data The tests were unsuccessful as the transmitters interfered with their nearby receivers A way round this problem could not be found and the technique was abandoned Consequently when using multiple modules it must be en sured that none transmit at the same moment as others The trans mission periods are only brief and it is quite easy to stagger the timings so that overlaps do not occur If overlap does occur press the Reset switch on any board to restart the PIC program to allow transmis sion at a slightly later time than used by other boards in sequence All transmissions must take place within a period of 60 seconds The use of the Test switches S3 will show whether or not overlap is occurring when examining the PC Main screen and its timing display boxes on the left It may be useful to have a second person to help in this staggering It may however prove tricky to have more than one S3 switched on at the same time We hope the use of this design will help you to economise on electricity use EPE 43 SHERWOOD ELECTRONICS Buy 10 x 1 Special Packs and choose another one FREE 15 x 5mm Red LEDs SP135 5 x Miniature slide switches 12 x 5mm Green LEDs SP136 3 x BFY50 transistors 12 x
13. Its output pulses at pin 3 are fed to one of the clock inputs CPO pin 14 of IC2 via gates IC1b and IC1d the latter connected as an inverter This means that the clock pulses from IC1a cannot reach the clock input ofIC2 unless pin 5 of IC1b is pulled high ie to open the gate Normally however this pin is held low by pin 10 of IC1c as this gate has both of its inputs pulled high one di rectly and the other via a 10kQ resistor As aresult when power is first applied to the circuit IC1a begins oscillating but none of its pulses can reach IC2 to start the counter Instead IC2 is merely reset by the 100nF capacitor and 10kQ resistor connected to its MR input pin 15 and then just sits in this state This in turn means that the only output of IC2 which is at a logic high is its OO output pin 3 and so all the relay driver circuits are off Now consider what happens when one ofthe four selector pushbuttons S1 to S4 is pressed Because IC2 s outputs O1 to O4 are all initially low pressing any one of these buttons results in pin 9 of IC1c being pulled low as well As a result pin 10 of IC1c switches high and pulls pin 5 of IC1b high IC1b now allows clock pulses from IC1a to pass through to IC2 via IC1d which means that IC2 immediately be gins counting But it only does so until the output connected to the pressed pushbutton goes high As soon as this happens pin 9 ofIC1c switches high and its output sw
14. PC Oscilloscopes 128 megasample record length With class leading bandwidth sampling rate memory depth and an array of advanced high end features the PicoScope 5000 PC Oscilloscopes give you the features and performance you need without any compromise Advanced Triggers In addition to the standard triggers the PicoScope 5000 series comes as The PicoScope 3000 Series of oscilloscopes from Pico Technology standard with pulse width window dropout delay and logic level triggering includes general purpose and high resolution models VVith 14 bit 250 MHz Spectrum Analyser resolution and 175 accuracy the TOP Hz Picascope 34 4 is able to detect i i High speed USB 2 0 Connection changes as small as 0 024 244ppm making it t Sabato lo audet deser aeduniins TU huge Automatic Measurements speed B bit models In the PicoScope 3000 pm gt Arbitrary Waveform Generator eries feature sampling rates up to e p Define your own waveforms or select from 8 200MS s and up to 1 MS s record lengths 7 predefined signals with the 12 bit 125 MS s r general Pury nd portal ipplicati Waveform Platine Tool he PicoScope 2000 series oscilloscopes E PicoScope software now affer single and dual channel units jab a allows you to go back review rte HAE and analyse up to 1000 captures rtable low cost solutions t neral pu rhe St WIE D TES Went TOTTTE PAY Da Rie OE ward winning 25MHz handheld PicoScope 2105 fits omtortablv
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16. Takes you from beginner to A Level standard and beyond Contains all the hardware and manuals to assemble 500 projects You get 3 comprehensive course books total 368 pages Hardware Entry Course Hardware Advanced Course and a microprocessor based Software Program ming Course Each book has individual circuit explanations schematic and connection dia grams Suitable for age 12 Order Code EPL500 149 95 Also available 30 in 1 16 95 50 in 1 21 95 75 in 1 32 95 130 in 1 39 95 amp 300 in 1 59 95 details on website Tools amp Test Equipment We stock an extensive range of soldering tools test equipment power si pplies inverters amp much more Ts visit web site to see our full range of products Two Channel USB Pc ee This digital storage oscillo scope uses the power of your PC to visualize electrical sig nals Its high sensitive display resolution down to 0 15mV combined with a high band ots width and a sampling fre quency of up to 1GHz are giving this unit all the power you need Order Code VPCSU1000 289 95 Personal Scope 10MS s The Personal Scope is not a graphical multimeter but a com plete portable oscilloscope at the size and the cost of a good mul timeter Its high sensitivity down to 0 1mV div and extended scope functions make this unit ideal for hobby service automo tive and development purposes Because of its exceptional value for money
17. Transistors 4 sections Waveshaping Circuits 6 sections Op Amps 17 sections covering everything from Symbols and Signal Connections to Differentiators Amplifiers Single Stage Amplifiers 8 sections Multi stage Amplifiers 3 sections Filters Passive Filters 10 sections Phase Shifting Networks 4 sections Active Filters 6 sections Oscillators 6 sections from Positive Feedback to Crystal Oscillators Systems 12 sections from Audio Pre Amplifiers to 8 Bit ADC plus a gallery showing representative p c b photos DOE ELECTRONICS V2 0 id Mn sand cel mia Ks TK md 1 Lem PINE TEE Leni i TIO AUTRE e A ncm a ga cmm Virtual laboratory Traffic Lights Filter synthesis Digital Electronics builds on the knowledge of logic gates covered in E ectronic Circuits amp Components above and takes users through the subject of digital electronics up to the operation and architecture of microprocessors The virtual laboratories allow users to operate many circuits on screen Covers binary and hexadecimal numbering systems ASCII basic logic gates monostable action and circuits and bistables including JK and D type flip flops Multiple gate circuits equivalent logic functions and specialised logic functions Introduces sequential logic including clocks and clock circuitry counters binary coded decimal and shift registers A D and D A converters traffic light controllers memories and micropro
18. and four switches on the breadboard Some of the switches have a multiple function as will become apparent When the program is run the usual initialisation procedures take place There then ensues a routine in which the two numeric sides of dominoes are created At the moment they are represented by numbers 0 to 6 in the standard numeric form We shall illustrate later how they can be replaced by LCD symbols representing the dots pips on a normal domino The game is limited to seven domino tiles for each player you and the PIC Originally the author used QBasic to simulate the requirements for creating the 28 possible different domino faces in a normal set In passing it is worthwhile commenting that modern domino sets can be comprised of 28 55 91 136 or 190 tiles They are known respectively as Double 6 Double 9 Double 12 Double 15 and Double 18 sets In mathematical tilings the word domino often refers to any rectangle formed from joining two squares edge to edge The word is derived from the Latin dominus meaning 46 SELECT R1 10k Fig 10 1 Circuit for Mock Dominoes lord or master The oldest domino sets have been dated back to around 1120 possibly of Chinese origin General information on dominoes can be found at http en wikipedia org wiki Dominoes The Basic requi rements were trans lated into assembler for the PIC program The author often uses QBasic or Visual Basic to
19. cancel broadband altogether It then takes BT approximately two weeks to remove the broadband tag on your line until which time you cannot utilise any broadband supplier on that line at all ISPs that supply your broadband service are compelled to co operate with transfer requests by issuing a MAC code Details of the MAC transfer process and complaints procedure can be found at OFCOM s site at www ofcom org uk consumeradvice internet service switch mac users alike Linux almost child s play Although Net Work is an Internet not a computer column in recent issues I touched upon the subject of Linux the alternative operating system that gives Windows XP a serious run for its money especially as Linux is entirely free My thanks go again to reader Simon Faulkner who provided some helpful pointers I must admit to having next to no experience of using Linux which is only due to lack of time and not because of any prejudice on my part 66 The Asus Eee PC range is an extremely capable mini laptop running Linux or Windows with a solid state disk and 802 11g wifi that s finding favour amongst professional mobile workers families and young I decided to start a new project to see how cheaply I could put together an Internet enabled computer using free Linux and legacy computer parts So with an open mind I fetched Ubuntu from www ubuntu com burned the 700MB image onto a CD and then spun it up on a spare old Dell PC
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21. simulate the logic of ooogpooooo0 a complex routine 1700000000 before translating it 266 6 6 we oo into PIC assembler NOI The QBasic routine is shown in Listing 10 1 It produces all the possible permutations of the domino face sides from O blank to 6 The routine is Fig 10 2 Breadboard layout for Fig 10 1 Everyday Practical Electronics August 2008 Listing 10 1 DIM tile 28 b 0 CLS FOR c 0TO6 FOR a cTO6 tile b LTRIM STR c LTRIM STR a PRINT tile b b b 1 NEXT PRINT NEXT c PRINT b readily translatable for running through other forms of Basic The equivalent PIC routine is in the main program at label Tilesetup The permutations produced are 00 01 02 03 04 05 06 11 12 13 14 15 16 22 23 24 25 26 33 34 35 36 44 45 46 55 56 66 If you are familiar with dominoes you will know that the tiles can have their sides swapped over allowing 160 to be reversed to become 61 for example Consequently it is not necessary for a separate 61 tile to exist when there is already a 16 Each tile side is stored as one nibble 4 bits of a byte 8 bits Thus one byte holds the information for a single tile PICs can be told in which order they should hold their nibbles with the command SWAPE F where F is the address of the file whose nibbles are to be swapped The created tile value storage registers are allocated to be in PIC Bank 0 with an
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23. transistors Qla Qlb etc This circuit contains transistor switches using f the June 08 PIC N Mix feature OTHER DIGIT CONNECTIONS NOT SHOWN OTHER SEGMENT CONNECTIONS NOT SHOWN both common emitter Fig 2 and emitter follower Fig 3 circuit configurations We will look at these separately before tackling the full LED multiplexing circuit Saturation When using a transistor as a switch it is usual to want the transistor to go into saturation This 1s opposite to analogue linear amplifiers where normally we would want to avoid saturation as it would probably imply clipping of the signal Saturation is characterised by a small voltage drop between the collector and emitter called Vcesar which is typically around 0 1 to 0 2V From Fig 2 and Fig 3 it is clear that most of the supply voltage will appear across the load R if the transistor is saturated At this point it is worth noting that we are discussing bipolar junction transistors BJTs here and not field effect transistors FETs The term saturation is also used for FETs but has a different meaning In saturation the collector to emitter voltage across a bipolar transistor does not vary much with varying collector current SO we apply a more or less constant voltage to the load which is usually what we want However as we have discussed in recent Circuit Surgery articles LED brightness is actually dependent on current rather than forward
24. 16F84 as well as the 12F508 and 12F675 Order code NE36 18 50 270 pages INTRODUCTION TO MICROPROCESSORS AND MICROCONTROLLERS SECOND EDITION John Crisp If you are or soon will be involved in the use of microprocessors and microcontrollers this practical introduction is essential reading This book provides a thoroughly readable introduction to microprocessors and micrcontrollers Assuming no previous knowledge of the subject nor a technical or mathematical background It is suitable for students technicians engineers and hobbyists and covers the full range of modern micros After a thorough introduction to the subject ideas are developed progressively in a well structured format All technical terms are carefully introduced and subjects which have proved difficult for example 2s complement are clearly explained John Crisp covers the complete range of microprocessors from the popular 4 bit and 8 bit designs to today s super fast 32 bit and 64 bit versions that power PCs and engine management systems etc Order code NE31 22 00 298 pages 222 pages Everyday Practical Electronics August 2008 The books listed have been selected by Everyday Practical Electronics editorial staff as being of special interest to everyone involved in electronics and computing They are supplied by mail order direct to your door Full ordering details are given on the last book page FOR A FURTHER SELECTION OF BOOKS AND CDROMS SE
25. 230V or 110V as selected via the PC and is suited for 50Hz or 60Hz mains frequency Fig 1 shows an example of channel waveforms on the main screen An example of the recall and analysis screen is shown later The monitoring unit operates from the AC mains supply therefore it should only be built by someone who Rs EPE has been highlight is experienced with mains circuits or is suitably supervised by someone who Mains Monitor Main 15DECO7 Set Zero 1 07 27 13 A N dco ro e b om 53 38 54 47 NAN c2 C2 23 58 53 ue coc a N m Y O _ a Everyday Practical Electronics August 2008 Bias 424 Mult x 5 44 eo 12345 6 8 910111213141 15 Asan SIA DY th MainsMonitor Microsoft vi W Ref CHANNEL Set Mult ADC C Amps C Watts 1100 1000 E c2 n c 5 apc Hr 0 B X9 Mains Monitor Main 1 240v C 110v Com2 12 18 24 ADC 278 Sat 12 15 2007 23 59 55 Amps 3 6A Minutes 1435 Watts 914W EBX 11 33 Fig 1 Example of the PC main screen in mains monitoring mode is AC mains can be lethal if wrongly connected or simply misunderstood 35 Constructional Monitoring circuit The diagram for the monitoring circuit one channel is shown in Fig 2 As in other similar designs such as PIC Electric Mk2 Feb Mar 05 the author has used a Hall effect transducer X3 to sense the current dra
26. 4 7nF MKT polyester Resistors 0 25W 1 1 22kQ 1 390 2 10k 4 1000 4 1kQ As a result IC2 stops with its O1 O2 O3 or O4 output high depending on which button was pressed This high output turns on its associated relay driver transistor thus activating the relays for that channel and feeding the selected A V signals through to the output sockets Of course this same process is re peated if any of the other buttons is pressed In which case IC2 is simply re activated and counts clock pulses until the output connected to the newly pressed button switches high IC2 then stops again with that output now effectively latched high instead of the previously selected output 12 This counting process happens so quickly that from the user s point of view the new A V source is selected as soon as its button is pressed And because of the latching action the chosen input source remains selected as long as the circuit is supplied with power or until one of the other selec tion buttons is pressed Diodes D1 to D4 across the relay coils are there to protect transistors Q1 to Q4 from transient back EMF spikes when the relays switch off In addition ared LED and a 1k series current lim iting resistor are connected across each pair of relay coils to indicate which channel has been selected Power source That s just about all there is to it apart from the power supply Power comes from a 12V DC 150mA plug pac
27. 4093B e fS L2N7000 um o heo Is IN I 2 Io lo To JI 4 7nF I 1000 e iq 2N7000 FOUR CHANNEL A V SOURCE SELECTOR Fig 1 the circuit uses eight mini DPDT relays four to switch the video signals and four to switch the audio These relays are driven by MOSFETs Q1 to Q4 which are in turn controlled by a one of four selector circuit based on quad Schmitt NAND gate IC1 and decade counter IC2 Everyday Practical Electronics August 2008 13 RELAY5 RELAY6 RELAY7 e No e e No e No e No e NC e NC e NC e NC COM COM COM COM e COL e e COL e e COL e e COL e RELAY8 AUDIO 1 IN RELAY AUDIO 2 IN RELAY2 No e No e No NC NC e NC e COM COM COM e aCOl e e cCOIL e e COl e AUDIO 3 IN RELAY3 AUDIO 4 IN CON9 e R o RELAYA No e NC e COM e coL e AUDIO OUT F pA CONIO e R e Ji gt gt IC2 4017B REGI 78L05 2 LL o LEDS POWER Oe oy Fig 2 follow this component layout and wiring diagram to build the Four Channel A V Selector The assembly is quite straightforward but do make sure that all polarised parts are correctly oriented anode A lead to the left Once it s in bend both leads forwards by 90 about 10mm above the board This will position the LED so that it will protrude through
28. 5mm Yellow LEDs SP137 4 x W005 1 5A bridge rectifiers 25 x 5mm 1 part LED clips SP138 20 x 2 2 63V radial elect caps 15 x 3mm Red LEDs SP142 2 x CMOS 4017 12 x 3mm Green LEDs SP143 5 Pairs min crocodile clips 135 Hunter Street Burton on Trent Staffs DE14 2ST 10 x 3mm Yellow LEDs Red amp Black 25 x 3mm 1 part LED clips SP144 5 Pairs min crocodile clips Tel 44 0 1283 565435 Fax 44 0 1283 546932 100 x 1N4148 diodes assorted colours 30 x 1N4001 diodes SP146 10 x 2N3704 transistors 7 30 x 1N4002 diodes SP147 5 x Stripboard 9 strips x Chips Parts 2 W A 20 x BC182B transistors 25 holes ereo Imp 20 x BC184B transistors SP151 4 x 8mm Red LEDs 20 x BC549B transistors SP152 4 x amm Green LEDs amp Kits for Wide band Low distor 4 x CMOS 4001 SP153 4x 8mm Yellow LEDs E P E P t tion 11W channel 7 4 x 555 timers SP154 15 x BC548B transistors rojec S LU 4 x 741 Op Amps SP156 3 x Stripboard 14 strips x E de pti Stereo 20W Mono True E SP28 4 x CMOS 4011 27 holes A ogr a EP EF rms Real Power Y t SP29 4 x CMOS 4013 SP160 10 x 2N3904 transistors chips for most i ra SP33 4 x CMOS 4081 SP161 10 x 2N3906 transistors See Short Circuit amp Overheat e i Ml SP34 20 x 1N914 diodes SP164 2 x C106D thyristors se F m Protected Needs 8 lo a nd Tg SP36 25 x 10 25V radial elect caps SP165 2 x LF351 Op Amps eck our website or De LEG n E l SP37 12 x 100 35V radial elect caps SP166 20 x 1N4003 diodes 18V supply L tepore nnt SP
29. Gen 50MHZ HP 8563A 9KHZ 22GHZ Synthesised OSCILLOSCOPES HP 8560A 50HZ 2 9GHZ Synthesised Various opts 1 900 Gould J3B Sine Sq Osc 10HZ 100KHZ Low Distortion HP 8590A 10KHZ 1 5GHZ HP 3580A 5HZ 50KHZ ADVANTEST TR4132 100KHZ 1000MHZ Autoset TEKTRONIX 2445A 4 Channel 150MHZ Delay Sweep SIGNAL GENERATORS HP 5350B Counter 20 GHZ Cursor etc Marconi 2440 Counter 20 GHZ GOULD OS300 Dual Trace 20MHZ PHILIPS PM3217 Dual Trace 50MHZ Delay Sweep FARNELL DTV12 14 Dual Trace 12MHZ TEKTRONIX P6139A 100MHZ Probes Unused STEWART of READING 17A King Street Mortimer Near Reading RG7 3RS Telephone 0118 933 1111 Fax 0118 933 2375 www stewart of reading co uk CutputLcp 9am 5pm Monday to Friday used unused HP 83731A Synthesised 1 20GHZ 5 00 Marconi 2032 Sig Gen 10KHZ 5 4GHZ Opt 01 02 06 HP 8648A Sig Gen 0 1 1000MHZ Gigatronic 7100 Synth 10MHZ 20GHZ internal sweep mod 130 to 15dBM Marconi 2024 9KHZ 2 4GHZ HPIB used unused 1 250 HP 33120A Function Gen 100 microHZ 15MHZ T T 1 TG210 Function Gen 0 002HZ 2MHZ TTL etc R amp S APN62 Synth Function Gen 1HZ 260KHZ Bal Unbal Racal 1998 Counter 10HZ 1 3GHZ unused used boxes unused used Marconi 2022E Synthesised AM FM 10KHZ 1 01GHZ 500 EACUS mt ETE TIE SS Marconi 2019 A Synthesised AM FM 80KHZ 1040MHZ HP Agilent 34401A 6 1 2 Digit 150 195 Solartron 7150Plus 6 1 2 Digit True RMS IEEE with tem measurement 575 700 Fluke 77 serie
30. If you want the switching to occur when the temperature falls below a certain value diode D3 is reversed Op amp IC1b is an inverter which provides a signal opposite in polarity to IC1a s output When IC1a s output goes high IC1b s output goes low and vice versa Link LK1 provides the option for driving the relay with a rising temper ature L H or a falling temperature H L It selects the output of IC1a or IC1b to drive transistor Q1 which in turn drives the relay Diode D2 is there to quench the reverse voltage back EMF that is generated by the collapsing magnetic field of the relay coil each time it is switched off Power is obtained from the car s 12V ignition supply via diode D1 which gives reverse polarity protection The 10Q resistor 100uF capacitor and Zener diode ZD1 provide transient pro tection at the input of regulator REGI The circuit is powered via the 7808 regulator with the exception of the relay Q1 and LED which are driven from the 11 4V supply following diode D1 ResistoraGoloursGodes 4 Band Code 1 red red orange brown brown black orange brown brown grey red brown brown black red brown brown black black brown Everyday Practical Electronics August 2008 5 Band Code 1 red red black red brown brown black black red brown brown grey black brown brown brown black black brown brown brown black black gold brown Constructional Project device turns other d on or off
31. In what might be viewed as an act of divine Billgatesian intervention the Dell s hard disk promptly self destructed This was possibly due to ageing in storage but a second hard disk scrounged off eBay especially for the job joined its forebear in hard disk hell Disappointingly my zero cost objective was defeated which I put down to beginner s bad luck All went swimmingly well on a third hard disk and I was soon experiencing the Linux front end for the first time a clean and attractive GUI being viewed on a free high end Iiyama CRT monitor The USB mouse was found without a problem Helped by some Linux books from an Oxfam bookshop this is about price remember I configured the toolbar found my way to the all essential Terminal program and started to find my way around I am sorry to disappoint my Linux loving readers but progress is presently stalled by the need to install a USB wi fi adaptor wrapping a Linux shell around a suitable Windows driver This highlights one drawback namely the need for arcane command line operations that are not intuitive to seasoned Windows users my limited experience tends to reaffirm my belief that installing Linux the first time is a task for computer enthusiasts having some time on their hands Even so the necessary information can be Googled and it is only a question of devoting resources to completing the project in slow time I guess it is easy when you know how wa
32. LTD for O Please charge my Visa Mastercard Maestro Valid From Card expiry date Oad NO e ccectodcencses dinana ARARUNA A Maestro Issue No Card Security Code The last 3 digits on or just under the signature strip h m um um um um um EH EE EE EE EE o EE EMO REO REN EE EM EM EE EMO EN EN EN EM EE EMO EN EN EN EH EM EM EMO EN EN EN EN EM EN o EMO RN 62 Everyday Practical Electronics August 2008 Email editorial wimborne co uk John Becker addresses some of the general points readers have raised Have you anything interesting to say Drop us a line All letters quoted here have previously been replied to directly yx LETTER OF THE MONTH x PCB de soldering Being an R amp D engineer for a good number of years I have had the Occasion or two to remove soldered components from PCBs and have tried various methods Over the years I have read several techniques on the art of removing soldered components from PCBs Prompted by the letter in Readout and Alan s reply I thought I would offer the two techniques that I have found most effective and least damaging to PCBs tracks and plated through holes as follows 1 Apply a slightly hotter than normal soldering iron tip I use an electronically adjustable tip temperature iron to the joint to melt the solder and with iron applied blast the joint with a jet of compressed air from a canister the cans
33. PIC programmer module Book Experimenting with PIC Microcontrollers Book Experimenting with PIC C PIC assembler and C compiler software on CD PIC16F627A PIC16F88 PIC16F870 and PIC18F2321 test PICs USB adaptor and USB cable 164 00 Postage amp insurance UK 10 Europe 18 Rest of world 27 Experimenting with PIC Microcontrollers This book introduces PIC programming by jumping straight in with four easy experiments The first is explained over ten and a half pages assuming no starting knowledge of PICs Then having gained some experience we study the basic principles of PIC programming learn about the 8 bit timer how to drive the liquid crystal display create a real time clock experiment with the watchdog timer sleep mode beeps and music including a rendition of Beethoven s Fur Elise Then there are two projects to work through using a PIC as a sinewave generator and monitoring the power taken by domestic appliances Then we adapt the experiments to use the PIC16F877 family PIC16F84 and PIC18F2321 In the space of 24 experiments two projects and 56 exercises we work through from absolute beginner to experienced engineer level using the most up to date PICs PH28 Training Course 189 PIC training and Visual C training combined into one course All the features of the P928 course with an extra book teaching about serial communication The first two books are the same as the P928 The third book sta
34. Store 20 000 000 items on line NOW New items added dail Established for over 25 years UK company Display Electronics prides itself on offering a massive range of electronic and associated electro mechanical equipment and parts to the Hobbyist Educational and Industrial user Many current and obsolete hard to get parts are available from our vast stocks which include 6 000 000 Semiconductors 5 000 Power Supplies 25 000 Electric Motors 10 000 Connectors 100 000 Relays amp Contactors 2000 Rack Cabinets amp Accessories 4000 Items of Test Equipment 5000 Hard Disk Drives Display Electronics Telephone 29 35 Osborne Road 44 020 8653 3333 Thornton Heath Surrey UK CR7 8PD Fax 44 020 8653 8888 Rechargeable Batteries With Solder Tags NIMH NICAD AA 2000mAh AA 650mAh PP3 150mAh Instrument case with edge connector and screw terminals Size 112mm x 52mm x 105mm tall This box consists of a cream base with a PCB slot a cover plate to pro 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 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 44 866 battery pack originally intended to be used with an orbitel mobile telephone it contains 10 1 6Ah sub C batteries 42 x 22 dia the size usually used in cordless screwdrivers etc the p
35. The author s came from serial cable and is separate from the could be used instead although less RS Components TX module s It has to be powered conveniently Fig 4 RS232 PC interface circuit Da SIS Via SaM Onit TIO GU LE PC board Code 679 2 line 16 characters per line Capacitors Monitor available from the alphanumeric LCD optional 2 10pF ceramic O 2in pitch C2 EPE PCB Service see text X2 C3 Plastic case size and type to 4 way pinheader 1mm pitch 6 100nF ceramic 2 0in pitch individual choice TB1 C1 C6 to C8 C11 C13 3VA PC mounting mains 10 way pinheader and connector 22uF 25V radial elect C5 transformer twin 110V AC 1mm pitch TB2 C10 C12 C14 primaries 12V AC secondar 8 pin DIL socket 470uF 25V radial elect ies T1 RS 210 780 28 pin DIL socket C4 C9 mains plug socket and 4 Nylon self adhesive PCB cables to suit mounting pillars Resistors 0 25W 1 carbon film 6 way 15A mains screw ter 1000 R11 minal connector strip Semiconductors 2200 R9 R10 1A fuse and holder chassis 1N4148 signal diodes D1 D4 mounting FS1 15V 400mA Zener diodes D2 D3 single pole sub min toggle WO05 type 50V 1A bridge switches or alternatives rectifier REC1 see text S1 BC549 NPNtransistor TR1 Eds T PIC16F877A bio 2 que rouna caron switch push to make S2 preprogrammed see text IC1 presen JOM del Te eve SPST toggle switch S3 LM6462 dual rail to rail op amp IC4 VR1 VR2 3 27
36. address immediately following other CBLOCK allocated register addresses commencing at TILEO the other 27 tiles are not specifically mentioned as they are never called by name but register space is allowed for them Random routine Having created the 28 tile set a randomising routine is used to allocate seven tiles to each player ensuring that no repeats of any tile are produced This is done by placing xx into the used byte with the software ignoring any value of xX A simple randomising routine is used and is similar to the one used earlier in the series when dice throws were being simulated It is not totally random but is good enough for the current process A more sophisticated randomising routine is described next month Randomising here simply entails adding a primary number 7 in this case to a counter each time the randomising routine is accessed The value of the counter is then read and restricted to values below 32 before the tile selection choice is made according to the value held in the counter Values greater than 28 are ignored At the end of the full selection the unused tiles are also ignored in this game The selected tiles are stored in registers in Bank 1 commencing at h 60 for you and at h AQ for the PIC Your selected tiles are displayed on LCD line 1 Those for the PIC remain hidden Initially who starts the game is also subject to a randomised choice depending on the unsp
37. approx 5h output relay pulse or toggle selection MK139 Mini Kit Voice Changer Make your voice sound like a robot add vibrato effect use the pitch buttons and make your voice sound lower or higher built in microphone and power amplifier with volume con trol just add a speaker MK171 Mini Kit 7 95 7 95 Ultrasonic Radar Module Buzzer output fast slow con tinuous distance indication with 3 LED bar adjustable alarm LED alarm indicator dry contact NO NC relay VM125 Assembled 18 25 Mini PIC Application Module Create your own custom PIC application without the hassle of making the hardware 9 Free programmable I Os Onboard Relay LEDs amp Buzz er PIC16F630 inc VM142 Assembled 20 95 Over 300 Kits Mini Kits amp Modules Full Catalogue Available Prices Exclude Vat 17 UK Carriage 2 50 less than 1kg PLEASE ADD CARRIAGE amp VAT TO ALL ORDERS a Pie F 2 E Ei E w x JU gt E T m Sa ace 7 Lu DESIGN SUITE NEW IN DESIGN SUITE 7 NEW Redesigned User Interface includes modeless selection modeless wiring and intuitive operation to maximise speed and ease of use NEW Design Explorer provides easy navigation design inspection tools and cross probing support to improve quality assurance and assist with fault finding NEW 3D Visualisation Engine provides the means to preview boards
38. as well as the software having to be rewritten The author finds that the detailed thinking about the program structure builds up as a mental flow chart which does not require to be set down on paper It is acknowledged that in a commercial situation it would be mandatory for the program structure to be well documented with flow charts the program might eventually need to be changed by someone other than the original programmer In that case the flow chart would give a more immediate insight into the original programmer s thought processes However let us not deter you from drawing up flow charts if you prefer to do so You may well find that they help you to grasp what you are doing more readily than just relying on your mental visualisation processes To discuss flow charts more fully is beyond the scope of this tutorial although Everyday Practical Electronics August 2008 a simple example is given in Fig 10 3 but created in retrospect rather than prior to the program being written You will also find examples of them in Microchip s application notes It has to be said though that even in those which are full of program listings flow charts are not widely used Mike Hibbett also looked at the subject in PIC n Mix otage by stage Whether or not you use flow charts you should never attempt to write the entire program from beginning to end in one operation That way can lead to extensive problems when y
39. attractive to as many people as possible During the design phase we did give consideration to providing for compo nent video RGB switching However this would have required at least four extra relays five extra video connec tors and a larger and more expensive box to house the circuit So consid ering that most of the wide screen TVs and plasma panel screens which accept component video also have at least two input ports we decided to draw the line at S video and composite video switching Audio switching Similarly we decided not to worry about switching 5 1 or 7 1 channel analogue audio because in most cases these multiple channels must be decoded from Dolby Digital AC 3 or DTS digital surround signals and these are provided in the latter form by most DVD players set top boxes and so on Since digital decoders are mostly built into surround sound amplifiers anyway and are usually better than the decoders built into DVD players there s no real need to select the decoded and separated Everyday Practical Electronics August 2008 analogue audio signals It s far simpler and more efficient to select the digital bitstream signals instead In fact we believe this compromise approach has provided a selector unit that will serve the needs of the vast majority of people How it works Our Four channel A V Selector is really very simple Essentially it s just a set of four 4 pole switches with two
40. buffer The transmission of this data is then handled by the operating system and not by the application program Whether sending or receiving data it is clearly essential for the buffer to be of adequate size as it will otherwise overflow and some of the data will be lost This process is sometimes called hitting the buffers and it more or less guarantees a complete breakdown in communications between the PC and the peripheral device The InBuffer and OutBuffer parameters respectively set the sizes of the input receiving and output transmitting buffers These values set the buffer sizes in bytes The default values will usually suffice but higher values might be needed in applications that send or receive large blocks of data The size of the buffer must be significantly larger than a single block of data Sending data Sending data using MSComm is very simple and the only minor complication is that in common with most serial port components it is designed primarily for sending and receiving data in the form of strings In the current context it will usually be the transfer of numeric data that is required Fortunately in basic it is easy to convert numeric data to strings and vice versa Everyday Practical Electronics August 2008 To test the sending of data using MSComm add a scrollbar and a command button to the form The scrollbar properties should be edited so that the maximum and minimum values are 0 and
41. confirm the principle is practical Panels made with a large number of LEDs find all kinds of uses from Christmas decorations to art installations so it is a valuable example Using the example of a display panel allows us to simultaneously cover another interesting topic multiplexing Multiplexed displays When constructing a display with a huge number of LEDs it isn t practical to wire each LED to its own individual I O pin It s possible of course but not desirable as you will have to find 1024 I O signals from somewhere Multiplexing is a technique that allows many LEDs to share a single output pin but still be individually controllable The principle of the technique is shown in Fig 1 Here a panel of 25 LEDs arranged as an array of five by five is controlled by only 10 processor output pins Conceptually you turn on a single row of LEDs by turning on its control signal a single wire connected to Port B in this example and immediately place the values that you want to see low for off high for on onto the five data outputs of Port A Now comes the clever bit you then turn off the row signal turn on the control signal for the next row down and output the data that you want to appear on that line of LEDs and continue ad infinitum Do this fast enough and the eye will not be able to see fact that you are only actually displaying one row of LEDs at a time Persistence of vision This trick works because the
42. having a metal delivery tube are better than those with plastic tube as these tend to melt This is not very health and safety considerate as hot molten solder flies everywhere be sure to wear protective Godfrey Manning s photospectrographs Recently on the Chatzone via www epemag co uk reader Derek posted the following I am so impressed with the photo spectrographs by Godfrey Manning Readout in the June issue that I must ask if Mr Manning could tell us how he achieved such excellent results However I understand and respect that Mr Manning may not wish to make his research public so can anyone offer a method of taking such pictures Knowing that Godfrey is not a CZer I emailed him to ask how he did them He replied The spectroscope is a basic prismatic device sold for educational purposes by Rapid Electronics their order code 06 6560 The trouble is it s meant to be looked down by eye at close quarters I tried a so called T mount that enables a camera body to mount on a microscope the eyepiece then projecting the image onto the focal plane of the camera It didn t work So now I use a standard lens at close focus extended by a macro tube the T mount goes on the filter ring of the lens with appropriate adapters and supports the spectroscope 64 gloves goggles and a lab coat and perform the operation away from others I remove as much solder as possible from the joint prior to applying this te
43. in the context of a mechanical design prior to physical prototyping NEW Simulation Advisor includes reporting on simulation problems with links to detailed troubleshooting information where appropriate NEW Trace capability within both MCU and peripheral models provides detailed information on system operation which allows for faster debugging of both hardware and software problems NEW Hundreds of new device models including PIC24 LPC2000 network controllers and general purpose electronic components Electronic Design From Concept To Completion l abcenter V www labcenter com Electronics E mail info labcenter com Tel 44 0 1756 753440 Labcenter Electronics Limited Registered in England 4692454 Fax 44 0 1756 752857 Registered Address 53 55 Main Street Grassington North Yorks UK BDes3 5AA
44. instrument are explained in simple terms with a minimum of mathematical analysis The book covers analogue and digital meters bridges oscilloscopes signal generators counters timers and frequency measurement The practical uses of these instruments are also examined e go 1d ele M zd Om 0 9 95 274 pages 28 99 206 pages DIGITAL GATES AND FLIP FLOPS lan R Sinclair This book intended for enthusiasts students and technicians seeks to establish a firm foundation in digital electronics by treating the topics of gates and flip flops thoroughly and from the beginning Topics such as Boolean algebra and Karnaugh mapping are explainend demonstrated and used extensively and more attention is paid to the subject of synchronous counters than to the simple but less important ripple counters No background other than a basic knowledge of electronics is assumed and the more theoretical topics are explained from the beginning as also are many working practices The book concludes with an explanation of microprocessor techniques as applied to digital logic Order code PC106 9 05 UNDERSTANDING ELECTRONIC CONTROL SYSTEMS Owen Bishop Owen Bishop has produced a concise readable text to introduce a wide range of students 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 principles and techniques ins
45. longer available so I purchased the Edirol UM 2 made by Roland If a computer has no MIDI port but is equipped with USB this interface will add a MIDI input and two MIDI outputs Whats more it comes with a CD ROM of drivers for all operating systems from Windows 98 to XP with special instructions for Vista and also for Mac OS A product that thoughtfully acknowledges the existence of Windows 98 is rare these days It also costs less than the Yamaha device Surprisingly it all installed quickly deposits of solder especially under ICs and similar I use a small stiff plastic bristle brush for this Using the above techniques I have recently removed successfully and without damage to a double sided PCB a 68 pin SCSI connector This item has four rows of 17 pins spaced just over Imm apart quite dense and without any easy way of cutting the component to remove pins individually I would recommend that where possible components are cut and leads or pins dealt with on an individual basis Tracks especially if they are fine can be lifted and broken due to excessive heat and if the pins are a bit tight the plated through holes can be destroyed but used with care and caution these techniques I have found to be very useful especially with multi pin components Ed Bye via email Thanks Ed that sounds highly workable for those with the right gear and faultlessly on my 98SE system that s saying something I bought
46. need registering FREE with Designsoft TINA and your own circuits components and i c s e Matrix Multimedia Flowcode details are given within the packages Easy to use digital interface e Animation brings circuits to life e Vast library of logic macros and 74 series i c s with data sheets e Powerful tool for designing and learning Hobbyist Student 45 inc VAT PROJECT DESIGN WITH CROCODILE TECHNOLOGY SET Bese ene An Interactive Guide to Circuit Design Site Licence 599 plus 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 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 for detailed background information with many animated diagrams A high quality Nearly all the circuits can be instantly simulated in Crocodile Technology not included on Ereflzrer ies Or maven 200 jpg images of electronic Get TINA Flowcode for a total of just 50 including VAT and postage the CD ROM and you can customise the designs as required WHAT S INCLUDED Light Modules Temperature Modules Sound Modules Moisture Modules Switch components This Modules Astables including 555 Remote Control IR amp Radio Transistor Amplifiers
47. only it were that simple Before a single line of code is written there is a great deal of thought involved about the overall objective and how each step on the set first address for CG RAM write Set for sub page 4 get symbol data send to LCD CG RAM clear PCLATH way to achieving it might be performed Part of this consideration relates not only to the logic of the software routines but also to the control requirements of external interfaces There are two schools of thought about the planning The first considers that the use of flow charts is an essential requirement The other doesn t The advantage of using a flow chart is that it shows the questions and answers of each stage of the program in a diagrammatic form Theory says that this chart then enables the code to be written to meet each of the requirements illustrated The use of a flow chart certainly helps in concentrating immediate thought processes and in recapturing concepts in the future but it cannot display the command by command reasoning of each line of code Only the code itself shows that unless you also translate each line of code into lengthy textual comments in which case there is the danger of getting bogged down with words Additionally there is always the possibility that some logical consideration has been omitted from the flow chart and which only comes to light once you try to run the program requiring the chart to be redrawn
48. or Switch or send cheque PO All prices include VAT if applicable White LED and Motors Experimenting with PIC C The second book starts with an easy to understand explanation of how to write simple PIC programmes in C Then we begin with four easy experiments to learn about loops We use the 8 16 bit timers write text and variables to the LCD use the keypad produce a siren sound a freezer thaw warning device measure temperatures drive white LEDs control motors switch mains voltages and experiment with serial communication Web site www brunningsoftware co uk Our PIC training system uses a very practical approach Towards the end of the second book circuits need to be built on the plugboard The 5 volt supply which is already wired to the plugboard has a current limit setting which ensures that even the most severe wiring errors will not be a fire hazard and are very unlikely to damage PICs or other ICs We use a PIC16F627A as a freezer thaw monitor as a step up switching regulator to drive 3 ultra bright white LEDs and to control the speed of a DC motor with maximum torque still available A kit of parts can be purchased 31 to build the circuits using the white LEDs and the two motors See our web site for details Mail order address Brunning Software 138 The Street Little Clacton Clacton on sea Essex CO16 9LS Tel 01255 862308 Readers Circuits WIN A PICO PC BASED OSCILLOSCOPE WORTH 799 20
49. ose Everyday Practical Electronics August 2008 39 o EN CIRCUIT SURGERY REGULAR GLINIC BY IAN BELL Transistor Saturation John Becker discussed a problem that reader John Pugh was having with a circuit The circuit in question used a PIC to drive a multiplexed LED display which unfortunately suffered from variable brightness depending on the number of segments lit If only one or two segments were lit the LEDs were very much brighter than when more segments were on The PIC N Mix article concentrated on diagnosing the problem what was the fault It could be the display the transistors or the software John suggested some diagnostic tests and eventually the reader replaced the anode transistors with Darlington devices and the problem was solved Following on from that this month s Circuit Surgery will focus on using transistors as switches covering some basic concepts concerning the saturated and non saturated operation of bipolar transistors We then analyse the LED drive circuit and thankfully arrive at the same conclusion as last month s practical approach In Fig l is shown the circuit discussed in June s PIC N Mix only one digit and two segments are shown here but the full circuit has six digit switch transistors Q2 connected to the common anodes of each 7 segment display Each display has eight LEDs seven segments and a decimal point The cathodes connect to the segment switch
50. powerful and flexible remote control system The same transmitter may be taught to work with any number of receivers to create master keys Visit www rfsolutions co uk for more information CLASS D DESIGN Midlands based company Class D Design Ltd is selling its own brand of pro audio loudspeakers to end users and installation companies The company has been trading for seven years and is now moving into the pro amplifier market This is a market that has been dominated by Far Eastern imports These use bipolar transistors and in some cases switching MOSFETS These can be unreliable due to thermal control issues and this problem is sometimes exacerbated by sub standard copied components Class D is introducing a range of lateral MOSFET amplifiers These use their own proprietary ALFET devices Class D is the only manufacturer of stable oscillation free double die plastic lateral MOSFETS in the world These are UK made of a guaranteed quality and do not suffer from thermal issues As such these highly reliable amplifiers are available at competitive costs with superior quality and reliability In addition Class D manufacture their own zero voltage switching control chips using Class D proprietary silicon again manufactured in the UK and specifically aimed at the audio and lighting markets They offer full research design and development facilities The range comprises amplifier kits for DIY enthusiasts 200W to 200
51. robots that work first time With this book you can get up and running quickly building fun and intriguing robots from step by step instructions Through hands on project work Owen introduces the programming electronics and mechanics involved in practical robot design and build The use of the PIC microcontroller throughout provides a painless introduction to programming harnessing the power of a highly popular microcontroller used by students hobbyists and design engineers worldwide Ideal for first time robot builders advanced builders wanting to know more about programming robots and students tackling microcontroller based practical work and labs The book s companion website at http books elsevier com companions 9780750665568 contains downloadable files of all the programs and subroutines program listings for the Quester and the Gantry robots that are too long to be included in the book 366 pages Order code NE46 21 99 NEWNES INTERFACING COMPANION Tony Fischer Cripps A uniquely concise and practical guide to the hardware applications and design issues involved in computer interfacing and the use of transducers and instrumentation Newnes Interfacing Companion presents the essential information needed to design a PC based interfacing system fromthe selection of suitable transducers to collection of data and the appropriate signal processing and conditioning Contents Part 1 Transducers Measurement systems Tem
52. the components are placed on the PC board Don t forget to reverse diode D3 if link LK1 is in the H I position 32 thermistor to react quickly even to small temperature variations the thermistor should be left exposed However if the reaction speed isn t so important but durability is you can pot the thermistor in high temperature epoxy and mount it in the end of a threaded brass fitting Either way the thermistor will need to be connected to a length of shielded single core cable with the shield the braid connecting to the OV terminal on the PC board The thermistor isn t polarised it can be connected either way around Insulate the leads of the thermistor using heatshrink tubing so that they cannot short out to each other or to ground 0V In many cases the whole thermistor itself can then be covered in heatshrink without slowing its reac tion time too much Testing Once the assembly is complete it s a good idea to bench test the module to make sure it works correctly To do this you ll need to connect the ther mistor to the input terminals remem ber braided side of the shielded cable to OV and supply power and earth Everyday Practical Electronics August 2008 Constructional Project The thermistor s leads should be insulated and then covered in heat shrink tubing so that short circuits can t occur If durability in extreme conditions is required and the sensor doesn t need
53. the drop across the base resistor changing as the base current changes This circuit is not really a very good switch Analysis The previous discussion has given some insight into transistor operational regions and the switching properties of the two configurations used in Fig l The change in load voltage observed for the emitter follower transistor leads us to suspect that this might be responsible for the LED brightness variation described in the PIC N Mix feature We can confirm this by some further circuit analysis Fig 4 shows one digit and one segment from Fig 1 with the segment on and labels for the voltage drops in the circuit The total of these voltage drops from ground to supply is equal to the supply voltage So Vec V c sar Vrs Vg t Vag Vg Where V is the forward voltage drop of the LED which we will assume to be about 2V Note that the LED current in each on segment is I For simplicity we assume the components in each segment are exactly the same so all the LED currents are equal The individual segment currents flow separately through the segment switch transistors Qla QIb etc but for each digit they combine to all flow through the digit switch transistor Q2 in Fig 4 So if n segments are on then Q2 s collector current is nJ The resistor voltage drops are dependent on the LED current Va 1 R1 2 nIRI f Vig 1 R3a Substituting these in the above equation we get Voc Veesar l
54. to react quickly it can be potted in high temperature epoxy and mounted in the end of a threaded brass fitting SETPOINT VRI HYSTERESIS F VR2 Lum i BEL Alp Tolo First turn hysteresis trimpot VR2 just above IC1 fully anti clockwise Then turn set point pot VR1 anti clockwise until the relay clicks and LED1 comes on Because VR1 is a multiturn pot you may need to rotate it a number of times before the LED lights Once the switch has tripped you can then turn VR1 set point back clockwise just enough to turn off the LED and disengage the relay Now when you heat the thermistor the LED should immediately come on and the relay click over cool ing the thermistor should cause the LED and relay to turn off again fairly quickly Finally turn VR2 hysteresis clockwise a little and you should find that the switch takes longer to turn back off when itis being cooled down after being tripped THERMISTOR CHASSIS TEMPERATURE SWITCH PC BOARD OV Fig 3 here is a typical connection set up where the Temperature Switch might be monitoring the temperature of an audio amplifier The relay s normally open NO connection is made to the ignition switched 12V while the adjacent common com terminal is connected to a fan The other side of the fan is earthed When the temperature rises to the set point the fan is triggered The setting of the hysteresis pot determines how low the temp
55. variation We will use 6 100 I 10mA R 430Q as above If Vc is around 0 1V we can approximate the voltage across R to exactly 5V to keep things simple For R 25 load halved I is 200mA and the forced beta is 20 confirming saturation For R 100 load doubled I is 50mA and the forced beta is 5 again confirming saturation Looking at Fig 1 which also has a supply voltage of 5V we can find the approximate base current for Qla Qlb etc using I V R 5 0 7 470 9mA The maximum LED current pulsed stated in PIC n Mix is l60mA so 9mA gives a forced beta of around 18 so the segment transistors should be saturated assuming the gain of the transistors used is much higher than 18 Fig 3 Switch using a BJT in emitter follower configuration Approximate voltages Moving to Fig 3 to look at the emitter follower transistor we can work out some approximate voltages If we assume the transistor is in the active region with p 100 a collector current of 100mA a base current of 1mA then what is the voltage at the emitter and hence across the load We might immediately assume that it is one Vy drop below the supply at 4 3V ie 5 0 7 assuming Vy 0 7V However this ignores R which drops 0 47V with 1mA through it So the emitter voltage would be 5 0 47 0 7 which is about 3 8V This gives 100mA load current and hence collector current with R 38 as the load Everyday Pra
56. when you are the one to select a tile but is otherwise turned off The two commands that control this function are movlw b 00001101 display on cursor underline off cursor blink on call LCDLIN and movlw b 00001100 display on cursor underline off cursor blink off call LCDLIN Note that any command that is sent to the LCD is always made via the LCDLIN sub routine Two tile faces have to be highlighted simultaneously and two cursor position addresses are alternately sent to the LCD rapidly moving the highlight back and forth across a double pair by repeatedly calling routine SELECTCURSORVAL while a switch press is awaited SELECTCURSORVAL bcf STATUS C rif SELECTLOOP W iorlw b 10000000 47 NEW GAME TILE SELECT STARTER SELECT DOUBLE FOUND NEITHER PLAYER HAS DOUBLE SHOW WINNER NEITHER PLAYER HAS MATCH YES SWAP PLAYER ALL TILES PLAYED Fig 10 3 Flow chart for the game call LCDLIN bcf STATUS C rlf SELECTLOOP W iorlw b 10000001 call LCDLIN return SELECTLOOP holds the address of the tile to be highighted which is repeatedly swapped between the LCD addresses of the two sides of the tile selected The LCD cursor address is basically twice that of the tile register address hence the two commands RLF SELECTLOOP W It is the value of the SELECTLOOP bit 0 held in W which determines the LCD address which 1s to be highlighted Tile face type As things stan
57. you intend using an AC input signal see below Testing OK now for the smoke test You will need a 12V DC supply rated at about 150mA to power the board Connect this to the 12V and OV terminals mak ing sure you get the polarity right Initially when you apply power noth ing should happen You can now check if the circuit works by connecting the negative signal input to OV and the positive input to the 12V rail When you do so the relay should immediately switch on and the LED should light How to use it Fig 3 shows three different circuit configurations that can be used to trigger the relay board Fig 3 a shows how to turn the relay on using a signal output that goes high ie to 5V or 12V Conversely Fig 3 b shows how to rearrange the wiring so that the relay turns on for a signal output that goes low ie to OV fablemigResistomGolourGodes 4 Band Code 1 red red orange brown brown black orange brown red red red brown brown black red brown 5 Band Code 1 red red black red brown brown black black red brown red red black brown brown brown black black brown brown 24 Everyday Practical Electronics August 2008 OV 12V EXISTING CIRCUIT RELAY ON WITH OUTPUT AT 5V OR 12V Constructional Project OV 12V EXISTING b CIRCUIT RELAY ON WITH OUTPUT AT OV OV 12V LED DRIVING CIRCUITRY INDICATOR LED OR IN REVERSE ORDER RELAY ON WHEN LED INDI
58. 0MHz Analogue Bandwidth Dual Channel Storage Oscilloscope Spectrum Analyser Frequency Meter ef Multimeter USB Interface i you have a novel circuit idea which would be of use to other readers then a Pico fTechnology PC based oscilloscope could be yours Every 12 months Pico Technology will be awarding a PicoScope 3206 digital storage oscilloscope for the best IU submission In addition a PicoScope 2105 Handheld Scope worth 199 will be presented to the runner up Ingenuity Uniimited Our regular round up of readers own circuits Universal Ding Dong No more chimes blues o YOU found those chimes at an antiques fair and would like to use them as a ding dong doorbell Or you bought those gongs at a market in Asia but can t work out how to wire them to the pushbutton on your patio Here s the solution in Fig 1 The circuit activates two solenoids in sequence to strike two chimes or gongs one when your doorbell is pressed the other when it is released When pushbutton S1 the front doorbell is first pressed C2 instantly charges This C1 100001 prevents switch bounce which might cause solenoid L2 to trigger prematurely L2 is likely to activate briefly on power up Cla and IClb form a positive edge triggered monostable timer so that when pins 1 and 2 go high TRI conducts for a fraction of a second activating solenoid L1 Diode D1 suppresses back EMF which could destroy ICI in parti
59. 0W RMS amplifier modules up to 3000W RMS active speakers complete amplifiers power supplies energy saving lighting products and bespoke designs for OEM and custom manufacturers The THD figures are better than 0 005 and noise floors better than 110dBs For further information phone 01623 654080 or mobile 07980 600373 or browse www class d com 12GHz USB sampling oscilloscope Pico Technology has unveiled the PicoScope 9201 a dual channel PC sampling oscilloscope with a bandwidth of 12GHz that redefines the performance of sampling oscilloscopes at this price level The dual channel PicoScope 9201 uses sequential equivalent time sampling to achieve a sampling rate of 5TS s The wide bandwidth allows acquisition and measurement of fast signals with a transient response of 50ps or faster Timebase stability accuracy and a sampling interval of 200fs allow timing characterisation of Jitter in the most demanding applications The ability to trigger on high frequencies up to IOGHz allows measurements on microwave components with extremely fast data rates The PicoScope 9201 is available from local distributors or direct from Pico Technology at www picotech com for 5 995 VAT and delivery NEW SERIAL EEPROM Microchip has announced a serial EEPROM family using a new single I O bus Key facts UN I OTM single I O bus interface 1 Kbit to 16Kbit memory size in 3 pin SOT 23 package 1 8V operation 10kHz to
60. 100kHz data rate advanced reliability features The devices are based on Microchip s patent pending UN I OTM memory device protocol The 11XX010 11XX020 11XX040 11XX080 and 11XX160 are the first single I O EEPROM devices that can support data rates from 1OKHz to 100kHz and the only 1 2 4 8 and 16 Kbit EEPROMs available in a 3 pin SOT 23 package in addition to other higher pin count packages The UNIO bus and EEPROM devices were developed in response to market trends toward smaller consumer electronic products with more features and functionality With this new bus only one Everyday Practical Electronics August 2008 I O pin is needed for communication between the EEPROM device and the microcontroller Evaluation is simplified because the UNI O memory devices are available in 8 pin packages The memory devices are supported by the new MPLAB Starter Kit for Serial Memory Products Part number DV243003 the MPLAB PM3 Universal Device Programmer Part number DV007004 and by software drivers available for Microchip s PIC MCUs at www microchip com The new devices are offered in two versions the 11 LCXXO versions operate from 2 5V to 5 5V and the 1LAAXX0O versions operate from 1 8V to 5 5V All of the new memory devices are available in 3 pin SOT 23 as well as 8 pin PDIP MSOP SOIC and 2x3mm TDFN packages Samples of the l6Kbit 11XX160 EEPROM devices are available at sample microchip com Forfurtherinformation
61. 130mm Low cost 1 99 115mm Draper 2 38 Wire Strippers 30mm Low cost 2 30 150mm Draper 5mm 5 86 Tools Ratchet Crimping Pliers High quality ratchet crimping pliers for various terminals including Automotive Data Power and Data connections Red Blue Yellow 5 80 BNC TNC RF series p RJ11 12 amp 45 Series p Non insulated crimps K Tools Crimp Pliers Green Red Blue 30 62 Red Blue Yellow 24 49 0 24 2 5mm crimps 30 62 0 5 6 0mm crimps 28 29 Non insulated crimps 28 22 Cable Ribbon 7 0 127mm Grey ribbon cable on a 0 05 1 27mm usn with a red nd stripe Supplied by 305mm 1ft or on full 30 5m 100ft reels Size per 305mm per Reel 10 Way 0 10 5 80 14 Way 4 16 Way 20 Way IDC GI tool CAT 5e Networking UTP Cable Conforms to CAT5E 100MHz standard ETA verified TIA EIA 568 B 2 305m Box 63 56 100m Reel 24 30 exc carriage RJ45 Outlet Kit Backing Box 2 Gang Plate RJ45 Module Blank Module Coloured id inserts 2 86ea 2 29 10 Tools Plastic punch down tool amp cable stripper Professional punch down IDC amp trim tool Outlets CAT5e Outlet Module 1Gang Plate 2 Mods 2 Gand Plate 4 Mods Module Blank 1 Module Blank 2 Module Blank 0 Other keystone outlets switches amp accessories avail able Patch amp Cross over leads from 0 Prices Exclude Vat 1 7496 a Cull goad a UK Carriage 2 50 less than 1kg uner
62. 2 0 ADC 0 Amps 0A Watts 0W You also have a choice of which notations are used at the left of the screen and whether the voltage is related to 230V or 110V RMS Click the respective radio button To return to the main recording screen click the Main button at the top right Clicking the screen s X button exits the program entirely Multiple unit use It is possible to have several moni toring units all running at the same time and each having different IDs They jointly send their data back to the PC This enables longterm monitoring of several power users simultaneously Additional copies of the TX board should be built to achieve this up to a total of 15 TX units Only one PC interface is needed The ID selection switches may be replaced by link wires inserted appropriately for each module in binary fashion You do not need an LCD for each module if you connect one viaa pin header and connector just swap between units if you want to check something There is a danger of transmission data from one TX module overlap ping data transmitted by another resulting in data not being received correctly In the early stages of design experiments were made by Everyday Practical Electronics August 2008 Select Units to show v Continuous Waveform amp 230v C 110V 3 H Start 4 54 8 5 MainsMonitor Microsoft vi XX Mains Monitor Main 15DE XY Mains Monitor Recalll Fig 9
63. 255 respectively In other words it is restricted to 8 bit values that the serial port can handle The button will be used to close the serial port and it should therefore be labelled something like CLOSE The following three routines are used for the form scrollbar and command button respectively Private Sub Form Load MSComm1 PortOpen True End Sub Private Sub HScroll1_Change MSComm1 Output Chr HScrolll Value End Sub Private Sub Commandl Click MSComml PortOpen False End End Sub The routine for the form simply opens the serial port using the PortOpen command There is no need to specify a port number since the port assigned to MSComml is the port that will be opened The routine for the scrollbar outputs the new value to the serial port each time the slider control is adjusted simply outputting the raw data from the scrollbar will not have the desired effect With a new value of say 145 the ASCII codes for the characters 1 4 and 5 would be sent to the serial port The Chr function is used to convert the new value to its corresponding ASCII character which 1s then sent to the serial port MSComml then converts this back to the appropriate 8 bit value and transmits it There seems to be no reliable alternative to this roundabout way of doing things The button can be used to close the serial port and itis considered good practice to close ports when a program will not be accessing them an
64. 3 the other way around In most applications once the Tem perature Switch is set it won t need to be altered The PC board fits into a 130 x 68 x 42mm plastic box so when the system is working correctly it can be inserted into the box and tucked away out of sight EPE Reproduced by arrangement with SILICON CHIP magazine 2008 www siliconchip com au Everyday Practical Electronics August 2008 Monit Design by John Becker Constructional Single Phase Watt Hour Meter Solid State Digital OF SCOTTISH amp SOUTHERN ENERGY PLC IEEE l Cl2 2000 MADE IN UK Reporter 5199K 20 100A W S50Hz 230V M e FR o8 t000 C Imp kWh PUSH AMPY AUTOMATION PETERBOROUGH UP PEG BSE ENGLAND Keep track of electricity use in your home ing the need for electrical energy conservation in projects and arti cles This design continues that theme and enables users to keep track of the AC mains power outlet use around their home or other premises allocating ID code numbers for individual sources The design monitors the amount of electrical power used up to 15A transmitting data via a radio link back to a central receiving unit connected to a PC via an RS232 serial COM port The PC displays and stores the data for future recall and simple cost analysis The PC software is believed to run with Windows platforms up to XP Its suitability for Vista is unknown The Mains Monitor may be used with AC mains of
65. 32 interface circuit in Fig 4 It uses the standard MAX232 serial interface chip IC6 The unit cannot be used directly with a USB port although there are serial to USB converters widely available browse www google com IC6 is fed by signals received by the 433MHz RF receiver RX mod ule IC5 and buffered by transistor TR2 The RX module is a matching 90mm AERIAL PART OF PCB 433MHz TX SOLUTIONS RS 310 9891 2 3T Constructional by a 9V DC source such as a PP3 type battery Regulator IC7 reduces the supply voltage to 5V as required by the RX and RS232 devices A separate aerial external con necting wire must be used with this module and may be of any suitable length as found by experiment SB AL The aerial used with the prototype cell was about 90mm long but greater SEE TEXT lengths may be required in other situations Assembly There are two PCBs for this de sign one each for the Monitoring Module and PC Interface These boards are available from the EPE PCB Service codes 679 Monitor and 680 Interface ju aie The S1 switch selection of moni toring module ID values can be made via a panel mounted binary selector switch so that the ID can be changed as the monitoring module is unit to the TX module from RF The interface receiver module is placed in different locations A PCB Solutions and is equally widely connected to the PC via a standard mounted DIL dual in line switch available
66. 38 15 x 47 25V radial elect caps SP167 5 x BC107 transistors Videte ji d E jn k S heatsink SP39 10 x 470 16V radial elect caps SP168 5x BC108 transistors inc 1 4 i igh I 30 n 5 SP42 200 x Mixed 0 25W C F resistors SP174 20 x 22 25V radial elect caps almost 30 years KIT 914 11 90 Stable Reliable SP47 5 x Min PB switches SP175 20x 1 63V radial elect caps amp Everyday Electronics high performan SP49 4 x 5 metres stranded core wire SP177 10 x 1A 20mm quick blow fuses ird Sl suci isse SP102 20 x 8 pin DIL sockets SP178 10 x 2A 20mm quick blow fuses SP103 15 x 14 pin DIL sockets SP181 5 x Phono plugs asstd colours To p K I ts Ultrasonic PEsT Scarer ran SP104 15x 16 pin DIL sockets SP182 20x4 7 63V radial elect caps a i SP109 15 x BC557B transistors SP183 20 x BC547B transistors l dom 32k pulses Kit867 19 99 SP112 4 x CMOS 4093 SP186 8 x 1M horizontal trimpots ICEbreaker P C16F877 in cir SP115 3 x 10mm Red LEDs SP189 4 x 5 metres solid core wire P I Metal Detector Micro based SP116 3 x 10mm Green LEDs SP192 3 x CMOS 4066 cuit emulator Kit 900 34 99 SP118 2 x CMOS 4047 SP195 3 x 10mm Yellow LEDs design sensitive Kit847 63 95 SP124 20x Assorted ceramic disc caps SP197 6 x 20 pin DIL sockets 1kV 500V Insulation Tester SP126 6 x Battery clips 3 ea SP198 5 x 24 pin DIL sockets Inc drilled case Kit 848 32 95 s Bat oe SP 100 4 Mixed 05W Gres o Eeoa lack coclets ur origina
67. 4 95 Additional DS1820 Sensors 3 95 each v items are available in kit fom KT suff re assembled and ready for use AS prefix or All prices INCLUDE 17 5 VAT Postage amp Packing Options Up to 2Kg gross weight UK Standard 3 7 Day Delivery 3 95 UK Mainland Next Day Delivery 8 95 Europe EU 6 95 Rest of World 9 95 up to 0 5Kg Order online for reduced price UK Postage ajor credit debit cards Make cheques PO s payable to Quasar Electronics m Please visit our online shop now for full details of over 500 electronic kits projects modules and publications Discounts for bulk quantities uu 4 Maestro masta VISA Electron SOLO 4 Ch DTMF Telephone Relay Switcher Call your phone num ber using a DTMF phone from anywhere in the world and re motely turn on off any i of the 4 relays as de sired User settable Security Password Anti Tamper Rings to Answer Auto Hang up and Lockout Includes plastic case 130 x 110 x 30mm Power 12Vdc Kit Order Code 3140KT 54 95 Assembled Order Code AS3140 69 95 8 Ch Serial Port Isolated I O Relay Module Computer controlled 8 channel relay board 5A mains rated relay outputs and 4 opto isolated digital inputs for monitoring switch states etc Useful in a variety of control and sensing applications Programmed via serial port use our new Windows interface termi nal emulator or batch files Serial cab
68. 68MHz crystal X1 78L05 5V 100mA voltage Hall Effect current transducer regulator IC3 RS 286 311 X3 AM RT4 433 transmitter module able from Magenta Electronics RF Solutions see text IC2 www magenta2000 co uk 1kQ R1 R8 10k R2 to R7 R14 to R16 100kQ R12 220kQ R14 Preprogrammed chips are avail 38 Everyday Practical Electronics August 2008 Constructional Mains Monitoring Board S2 e y RESET E am f K 1 d Ae ee B S e iE FS1 1A E lb INPUT A SEE TEXT ADC TEST X SEE TEXT DIL S1 TX AERIAL 90mm ALTERNATIVE TOGGLE SWITCHES 5 2in 132 1mm Fig 5 Assembly details for the mains monitoring PCB The identity code ID switches S1a d can be individual sub miniture toggle types a 4 way DIL or binary switch Everyday Practical Electronics August 2008 39 Constructional PC Interface Board REAR VIEW 2 3in OF PINS poe 1 7in 43 2mm Fig 6 Assembly details for the PC interface circuit Assembly and component layout details for the monitoring module are shown in Fig 5 those for the PC interface are in Fig 6 Assemble in the usual order of ascending component size starting with the on board link wires Note that some go under IC positions Observe the correct polarity for the semiconductors and electrolytic capacitors as shown on the PCB layouts Do not insert the DIL ICs RF modul
69. 9R3a V V nlR1 B CESAT Rearranging this equation to make I the subject we get Il V V V Vu R3a nRI f CESAT If V 25V Vg 0 1V V 22V V 0 7V R3a 10 R 470 2 we can plug some values in to get a formula for this specific circuit C Bus Shop bv C Bus and C Bus Wireless www cbus shop com Laser Business Systems Ltd Tel 44 0 20 8441 9788 Fax 44 0 20 8449 0430 Email info laser com 16 Garthland Drive EN5 3BB 56 I 2 2 10 470n D We see from this equation that the LED current is dependent on the number of LEDs which are on As n increases I decreases so the LEDs get dimmer when more of them are on This was observed with the problem circuit If 8 100 we get the following values for I LED 150mA 2 LEDs 115mA 3 LEDs 91mA 8 LEDs 48mA These values confirm that our assumption that Qla is saturated is true with a forced beta ranging from about 17 to 5 Similarly a check of circuit voltages confirms active region operation for Q2 It is important to check assumptions about transistor operating regions once a calculation is complete to check that the assumptions were valid The equation for I tells us that the larger the gain of the digit switch transistor the smaller the dimming effect will be Thus when the digit drive transistor is replaced with a Darlington pair the gain increases considerably and the effect of the number of LEDs on I d
70. ARNELL LT30 10 30 0 1A Twice 700 600 FARNELL L30 20 30v 0 2A THURLBY PL3300 32V 0 3A Digital Kenwood badged THURLBY PL3200 30V 0 2A Digitial TAKASAGO GM035 2 0 35V 0 2A 2 Meters 500 550 Used Equipment GUARANTEED Most Manuals supplied Please check availability before ordering or calling Prices plus carriage and VAT 59 EPE S PLEASED TO BE ABLE TO OFFER YOU THESE ELECTRONICS CD ROMS ELECTRONICS PROJECTS Logic Probe testing ce dee ERAT X ass Electronic Projects is split into two main sections Building Electronic Projects contains comprehensive information about the components tools and techniques used in developing projects from initial concept through to final circuit board production Extensive use is made of video presentations showing soldering and construction techniques The second section contains a set of ten projects for students to build ranging from simple sensor circuits through to power amplifiers A shareware version of Matrix s CADPACK schematic capture circuit simulation and p c b design software is included The projects on the CD ROM are Logic Probe Light Heat and Moisture Sensor NE555 Timer Egg Timer Dice Machine Bike Alarm Stereo Mixer Power Amplifier Sound Activated Switch Reaction Tester Full parts lists schematics and p c b layouts are included on the CD ROM ELECTRONIC CIRCUITS amp COMPONENTS V2 0 Circuit simulation screen Electronics Circuits amp
71. AS3117 24 95 Assembled with ZIF socket Order Code AS3117ZIF 39 95 ATMEL 89xxxx Programmer Uses serial port and any standard terminal comms program 4 LED s display the status ZIF sockets not included Supply 16Vdc Kit Order Code 3123KT 24 95 Assembled Order Code AS3123 34 95 Introduction to PIC Programming Go from complete beginner to burning a PIC and writing code in no time Includes 49 page step by step PDF Tutorial Manual Program ming Hardware with LED test section Win 3 11 XP Programming Software Program Read Verify amp Erase and 1rewritable PIC16F84A that you can use with different code 4 detailed examples pro vided for you to learn from PC parallel port Kit Order Code 3081KT 16 95 Assembled Order Code AS3081 24 95 Quasar Electronics Limited PO Box 6935 Bishops Stortford CM23 4WP United Kingdo Tel 08717 177 168 Fax 07092 203 496 E mail sales quasarelectronics com uasarElectronics com 0871 Payment We accept all Credit Card Sales PIC Programmer Board Low cost PIC programmer board supporting a wide range of Microchip PIC microcontrollers Requires PC serial port Windows interface supplied Kit Order Code VK8076KT 21 95 PIC Programmer amp Experimenter Board The PIC Programmer amp Experimenter Board with test buttons and LED indi cators to carry out educa tional experiments such as the supplied programming example
72. An easy to build adaptor for generating composite video signals Banish those cross colour interference blues SEPT 08 ISSUE ON SALE AUGUST 14 ADVERTISERS INDEX AREXX ENGINEERING AUDON ELECTRONICS BETA LAYOUT CRICKLEWOOD DISPLAY ELECTRONICS ESR ELECTRONIC COMPONENTS JAYCAR ELECTRONICS JPG ELECTRONICS LABCENTER LASER BUSINESS SYSTEMS LEKTRONIX LTD MAGENTA ELECTRONICS NURVE NETWORKS LLC PEAK ELECTRONIC DESIGN PICO TECHNOLOGY QUASAR ELECTRONICS SHERWOOD ELECTRONICS STEWART OF READING ADVERTISEMENT OFFICES SEQUOIA HOUSE 398a Ringwood Road Ferndown Dorset BH22 9AU PHONE 01202 873872 Fax 01202 874562 EMAIL epeads wimborne co uk For Editorial address and phone numbers see page 7 Published on approximately the second Thursday of each month by Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Printed in England by Apple Web Offset Ltd Warrington WA1 4RW 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 sups epemag wimborne co uk EVERYDAY PRACTICAL ELECTRONICS is sold subject to the following conditions namely that it shall not with
73. CATOR ON Fig 3 the various triggering options In a the relay board is triggered by a signal that goes from low to high 5V or 12V in b triggering is by a signal that goes to OV and in c by an external circuit that turns on an indicator LED Fig 3 c shows how to drive the re lay board from a circuit that normally powers an LED Note that if the LED is multiplexed when it is lit ie switched on and off at a fast rate the relay will chatter on and off Inserting link LK1 to connect the 1uF capacitor into circuit should stop this chattering In each of the three cases above if you want delayed switch on and switch off for the relay increase the value of the 1uF capacitor A value ANDRE LA MER j XGAMESTATION LEARN EBTEF HY EBrEP How TO DESIGN AND BUILD YOUR OWN VIDEO GAME CONSOLE Design inspired by the Atari 800 2600 Sinclair 4 Spectrom Apple l E Ee nuin Integrated IDE Li Op F a A hee e ess FEATURES ATi if Great for Hobbyists AND Students Complete Software Development Kit oBook on Designing the XGS Console Parallax SX Key Compatible a Fully Assembled XGS Micro Edition Unit J The Fun way to beam Embedded Systems WWW AGAMESTATION COM SUPPORT ONURVE NET PH512 266 23991us4 of 220uF will give a nominal 1 sec ond delay Itisimportant that the trigger circuit be capable of providing the required current to the relay board input The relay board will draw about 3
74. CTICAL SKILLS Learn how to identify Electronic Components Avoid Static Hazards Carry Out Soldering and Wiring Remove and Replace Components TEST EQUIPMENT How to Choose and Use Test Equipment Assemble a Toolkit Set Up a Workshop and Get the Most from Your Multimeter and Oscilloscope etc SERVICING TECHNIQUES The Manual includes vital guidelines on how to Service Audio Amplifiers The Supplements include similar guidelines for Radio Receivers TV Receivers Cassette Recorders Video Recorders Personal Computers etc TECHNICAL NOTES Commencing with the IBM PC this section and the Supplements deal with a very wide range of specific types of equipment radios TVs cassette recorders amplifiers video recorders etc REFERENCE DATA Diodes Small Signal Transistors Power Transistors Thyristors Triacs and Field Effect Transistors Supplements include Operational Amplifiers Logic Circuits optoelectronic Devices etc The Modern Electronics IV A prectical reference 1 electronics technmnola BE AG ESI NDA Bonart Panini Liar mre a The essential reference work for everyone studying electronics 9 Over 800 pages 9 In depth theory 9 Projects to build 9 Detailed assembly instructions 1 Full components checklists Extensive data tables 9 Manufacturers web links 9 Easy to use Adobe Acrobat format 9 Clear and simple layout 9 Comprehensive subject range 9 Professionally written Supplemen
75. Components V2 0 provides an introduction to the principles and application of the most common types of electronic components and shows how they are used to form complete circuits The virtual laboratories worked examples and pre designed circuits allow students to learn experiment and check their understanding Version 2 has been considerably expanded in almost every area following a review of major syllabuses GCSE GNVQ A level and HNC It also contains both European and American circuit symbols Sections include Fundamentals units and multiples electricity electric circuits alternating circuits Passive Components resistors capacitors inductors transformers Semiconductors diodes transistors op amps logic gates Passive Circuits Active Circuits The Parts Gallery will help students to recognise common electronic components and their corresponding symbols in circuit diagrams Included in the Institutional Versions are multiple choice questions exam style questions fault finding virtual laboratories and investigations worksheets ANALOGUE ELECTRONICS COREHEISIRSI EUNT stage Analogue Electronics is a complete learning resource for this most difficult branch of electronics The CD ROM includes a host of virtual laboratories animations diagrams photographs and text as well as a SPICE electronic circuit simulator with over 50 pre designed circuits Sections on the CD ROM include Fundamentals Analogue Signals 5 sections
76. D Non branded receivers won t pick up all services warns Lindsay Davies Freesat dares not guarantee that anyone with a Sky dish will be able to use it with a Freesat box this is because the Freesat services are spread between Astra 2D at 28 2 E as used by Sky and with a tight UK footprint and Eurobird at 28 8 E which has a wider footprint Dishes which are badly aligned on 28 2 may be even more off axis for 28 8 and give problems for Freesat Freesat promises to offer advice on which channels are the most likely to test a system Alba and Humax promise Freesat recorders later this summer Freesat has stuck deals with major high street outlets Argos Comet Currys and John Lewis plus some independent retailers Installation is very important says Lindsay Davis Retailers can also arrange installation by approved installers Emma Scott says this will cost from 80 including the dish John Lewis says standard installation costs 100 Installation We asked Lindsay Davis to elaborate on how customers can avoid buying receivers that they then try and plug into ordinary TV aerials and perhaps risk life and limb by trying to fit their own dishes We have not trivialised this says Lindsay Davis After customers buy a receiver they will be called by an installer who will go through a list of questions We are not pushing this as plug and play John Edwards director of comm u
77. E THE SHOP ON OUR UK WEBSITE www epemag co uk All prices include UK postage EASY PC CASE MODDING 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 panels for ones that are transparent This will then allow the inside of your computer and its working parts to be clearly visible There are now numerous accessories that are relatively inexpensive and freely available for those wishing to customise their PC with added colour and light Cables and fans can be made to glow interior lights can be added and it can all be seen to good effect through the transparent case Exterior lighting and many other attractive accessories may also be fitted This in essence is case modding or PC Customising as it is sometimes called and this book provides all the practical details you need for using the main types of case modding components including Electro luminescent EL go faster stripes Internal lighting units Fancy EL panels Data cables with built in lighting Data cables that glow with the aid of black light from an ultraviolet UV tube Digital display panels LED case and heatsink fans Coloured power supply covers 192 pages CD ROM Weli E 2M sey P 8 99 ROBOT BUILDERS COOKBOOK Owen Bishop This is a project book and guide for anyone who wants to build and design
78. John Clarke Control high current loads with a few milliamps TEMPERATURE SWITCH by John Clarke and Julian Edgar A cheap general purpose design that can work up to 245 C MAINS MONITOR by John Becker Keep track of electricity use in your home INGENUITY UNLIMITED Sharing your ideas with others Universal Ding Dong 10V to 12V LED Voltmeter TECHNO TALK by Mark Nelson Up close and personal PANs and NFC INTERFACE by Robert Penfold Assessing serial ports TEACH IN 2008 USING PIC MICROCONTROLLERS PART 10 by John Becker Examining a program s construction a game of Dominoes plus LCD symbol creation CIRCUIT SURGERY by lan Bell Transistor saturation PIC N MIX by Mike Hibbett More on I O port expansion NET WORK by Alan Winstanley Putting on a MAC Linux almost child s play Regulars and Serviees EDITORIAL NEWS Barry Fox highlights technology s leading edge Plus everyday news from the world of electronics PIC RESOURCES CD ROM EPE PIC Tutorial V2 plus PIC Toolkit Mk3 and a selection of PIC related articles ELECTRONICS MANUALS The Modern Electronics Manual and Electronics Service Manual on CD ROM BACK ISSUES Did you miss these PIC PROJECTS A plethora of PIC projects on CD ROM CD ROMS FOR ELECTRONICS A wide range of CD ROMs for hobbyists students and engineers SUBSCRIBE TO EPE and save money READOUT John Becker addresses general points arising DIRECT BOOK SERVICE A wide range of technical books availab
79. KT 12 95 Assembled Order Code AS3179 19 95 Bi Polar Stepper Motor Driver Drive any bi polar stepper motor using externally sup plied 5V levels for stepping IM and direction control These usually come from software running on a computer HE Supply 8 30Vdc PCB 75x85mm Kit Order Code 3158KT 17 95 Assembled Order Code AS3158 27 95 Bidirectional DC Motor Controller Controls the speed of most common DC motors rated up to 32Vdc 10A in both the forward and re verse direction The range of control is from fully OFF to fully ON in both directions The direction and speed are controlled using a single potentiometer Screw terminal block for connections Kit Order Code 3166v2KT 17 95 Assembled Order Code AS3166v2 27 95 AC Motor Speed Controller 700W Reliable and simple to install project that allows you to adjust the speed of an electric drill or single phase 230V AC motor rated up to 700 Watts Simply turn the potentiometer to adjust the motors RPM PCB 48x65mm Not suitable for use with brushless AC motors Kit Order Code 1074KT 12 95 Assembled Order Code AS1074 18 95 Box Order Code 2074BX 5 95 QUASAR electronics Get Plugged In Electronic Project Labs Great introduction to the world of electron ics Ideal gift for budding electronics expert 500 in 1 Electronic Project Lab Top of the range Com plete self contained elec tronics course
80. L fa g lt ui a Lj x REPEATED FOR EACH OF THE 32 COLUMNS GND Fig 2 Circuit diagram for the multiplexed LED panel that you reference the correct values in your software In our software we hard code that value within the DisplayRow function Each display row has a single transistor that connects between the corresponding port output pin and the row of LEDs The transistor is required here as potentially all LEDs on a row could be switched on which would result in a current flow that 58 exceeds the capability of the port expander IC No buffer transistors are required on the column output pins as only one LED 1s ever switched on in a given column The output pins of the MCP23S17 can like the PIC processor easily drive an LED To select a row of LEDs for display you drive the corresponding row pin low zero volts on the port expander To then turn on a particular LED drive a column pin low Drive the pin high to turn the LED off And that is it It s a very simple circuit as one would expect there just happens to be a lot of it due to the number of LEDs Constructing a circuit like this is a job for the more determined hobbyist One thing to bear in mind when driving LEDs in a multiplexed way they will appear Everyday Practical Electronics August 2008 much dimmer than when driving them directly This is simply because you are only turning the LED on for about 1 30th of the time compared to whe
81. LECTRONIC FILTERS Owen Bishop This book deals with the subject in a non mathematical way It reviews the main types of filter explaining in simple terms how each type works and how it is used The book also presents a dozen filter based projects with applications in and around the home or in the constructor s workshop These include a number of audio projects such as a rythm sequencer and a multi voiced electronic organ Concluding the book is a practical step by step guide to designing simple filters for a wide range of purposes with circuit diagrams and worked examples Order code BP299 5 45 188 pages ELECTRONIC PROJECTS FOR EXPERIMENTERS R A Penfold Many electronic hobbyists who have been pursuing their hobby for a number of years seem to suffer from the dreaded seen it all before syndrome This book is fairly and squarely aimed at sufferers of this complaint plus any other electronics enthusiasts who yearn to try something a bit different The subjects covered include Magnetic field detector Basic Hall effect compass Hall effect audio isolator Voice scrambler descrambler Bat detector Bat style echo location Noise cancelling LED stroboscope Infra red torch Electronic breeze detector Class D power amplifier Strain gauge amplifier Super hearing aid Order code BP371 5 45 PRACTICAL FIBRE OPTIC PROJECTS R A Penfold While fibre optic cables may have potential advantages over ordinary electric
82. NICS MANUAL CD ROM Simply complete and return the order form with ELECTRONICS SERVICE MANUAL CD ROM your payment to the following address i enclose payment of 29 95 for one manual or 49 90 for both manuals saving 10 by ordering both together Wimborne Publishing Ltd Sequoia House 398a Ringwood Road FULL NAME Ferndown Dorset BH22 9ND ADDRESS Price includes postage to anywhere in the World We will happily exchange any faulty E CODE out we do not offer a refund on these items SIGNATURE LJ enclose cheque PO in UK pounds payable to Wimborne Publishing Ltd ee _ _ odi Gee Ll Please charge my Visa Mastercard Maestro YOU S ud ES DERE x i ER you by first class mail or airmail Card o mee SoUe 0 normally within four working Valid From RU ecouilty Code the signature strip days of receipt of your order i i i i i I CD ROMs but since the content can be printed I I i lj t i I Expiry Date e Everyday Practical Electronics August 2008 21 Constructional Want to switch power to a high current load using a circuit capable of supplying just a few milliamps No problem build and use this low cost DC Relay Switch T S OFTEN NECESSARY to switch power to a device that requires a current of several amps in order to drive it The problem is the device that s required to do the switching may only be capable of supplying just a few milliamps Such a circuit m
83. NT 2000 XP inte grated software for the function 79 00 K8016 Kit 84 95 Full range of Velleman Test Equipment in sz also available PIC Programmer Suitable for a wide range of Microchip PIC mi crocontrollers onboard configurable 40 pin ZIF socket Microcontroller selection using patch jumper easy to use pro gramming PlCprog2006 software included SUBD con nector set included K8076 Kit 1A Power Supply Low cost universal symmetric power supply just add a suitable transformer and a heatsink trimmers can be replaced by po tentiometers to allow continuous ad 17 95 _justment of output LED output indicators K8042 Kit 9 59 057 9 ONTO COMPONENTS than 80 countries IC Programmer For Microchip FLASH PIC microcontrollers sup ports 4 different 300 mil PICs 8p 14p 18p and 28p test buttons and LED indicators Supplied with program ming examples amp easy connection to a PC through the serial port Supplied with a PIC16F627 and software to compile and program your source code K8048 Kit VM111 Assembled USB Interface A interface board with 5 digital input amp 8 digital output chan nels In addition there are two analogue inputs amp two ana logue outputs with 8 bit resolution All communication routines are contained in a Dynamic Link Library DLL You may write custom Windows 98SE 2000 Me XP applications in Delphi Visual Bas
84. RF Solutions The aerial for the TX module is part of the PCB and is of a fixed legal length Identity code Multipole switch S1 is connected to the PIC and is used to set the identity code of the monitoring board between 1 and 15 The switch outputs are biased normally high and turning on a switch sets a given output low At power on or reset the PIC reads the status of the switch outputs and sets the unit ID accordingly This ID is always transmitted with the total monitoring counts so that the re ceiving PC knows from which source the values have been sent Switch 52 is a reset switch which allows the PIC software to ii R3 TO R6 10k 21 n N N o o J gt Fe N gt Jo m Vpp CLK DATA l TX TEST SEE TEXT 2 Fig 3 Master control circuit diagram Everyday Practical Electronics August 2008 be restarted without power being switched off and on again Switch 53 allows the transmission of the PIC software s timing value when testing the module Provision has been made for an optional alphanumeric LCD X2 to be used with the monitoring module so that current ID values and moni toring quantities can be viewed at source Preset VR1 allows the LCD contrast to be set Connector TB1 is also optional it allows the PIC to be reprogrammed in situ if you wish It was used when developing the prototype unit COM interface Communication with the PC is via the RS2
85. The PIC that is performing all of the actual logic and timing for this example program requires only four signals to drive these chips A single chip select signal CS that enables all four devices simultaneously plus the three standard SPI signals SCK SDI and SDO The controlling microcontroller is a PICISF2520 chosen simply because it was to hand and works with the PicKit2 debugger No oscillator circuit is shown on the diagram none is needed as for simplicity we are using the internal oscillator of the PIC device and configured it to run at 32MHz It s not a high accuracy oscillator but for this circuit it doesn t need to be If you are using a processor that does not have a high speed internal oscillator then just use an external one as normal It will however need to run at a minimum of 30MHz The MCP23S17 has a reset input and we have wired all four chips up to a single resistor capacitor reset circuit We could have connected it to the processor reset input but if you want to keep the port expander part of your design on a separate circuit board it s better to keep the reset circuits separate too to protect them from electrical noise Each chip has its own unique address configured on the AQ Al and A2 lines The software needs to know what these addresses are obviously but the actual values you set are irrelevant Just make sure 957 5V 5V a z N mM m T H LL O I lt ui x O L
86. a matching hole in the front panel 14 Casing up The drilling details and dimensions for the specified low profile case is in dicated in Fig 3 Use the front and rear panel artworks as drilling templates or use the drilling diagrams Just attach copies of the artworks to the panels and drill and ream the holes to suit These panels are reproduced here full size Everyday Practical Electronics August 2008 N e l uel m At This is the view inside the completed prototype All parts except for connectors CON12 to CON16 switches S1 to S4 and the four indicator LEDs are mounted directly on the PC board Once the panels have been drilled you can prepare the labels by glueing the artworks onto adhesive backed A4 label paper The stickers can then be covered with clear packaging tape to protect them before cutting to size After that you just peel offthe back ing tape carefully affix each one to its panel and cut out the holes using a sharp hobby knife LLLLLDL The next step isto cut away the three moulded PC board support pillars in the bottom half of the case near the centre of the rear edge This is neces sary so that they don t interfere with the solder joints on the connector pins The plastic is quite soft and it s easy to cut away the redundant pillars with a pair of sharp side cutters That done fit the rear panel over the d
87. ack is new and unused and can be broken open quite easily 7 46 VAT 8 77 Please add 1 66 VAT 1 95 postage amp packing per order JPG Electronics Shaws Row Old Road Chesterfield S40 2RB Tel 01246 211202 Fax 01246 550959 www JPGElectronics com Mastercard Visa Switch Callers welcome 9 30 a m to 5 30 p m Monday to Saturday NEXT MONTH ULTRASONIC EAVESDROPPER Ever wanted to hear the unhearable sounds that are way beyond the range of normal human hearing What does the echo location chirp of a bat sound like What does your cat hear when its ears swivel like miniature radar dishes This low cost project answers these questions with a frequency down converter circuit that shifts ultrasonic sound signals to the human frequency range DON T GET CAUGHT OUT BY SPEED CAMERAS These days you can get points for driving just over the speed limit but what if your speedometer isn t quite accurate You might even get points when you think you are driving within the limit The Super Speedo Corrector will fine tune your cars speed measurement and keep you on the right side of the law THE VINYL FRONTIER Nowadays most hi fi amplifiers don t provide an input for turntables and a typical aux connection certainly won t have the correct RIAA filtering But with the Magnetic Cartridge Pre amp you can dust off your record player and resurrect your old 45s or LPs S VIDEO TO COMPOSITE VIDEO CONVERTER
88. ade payable to Direct Book Service or card details Visa Mastercard or Maestro to DIRECT BOOK SERVICE WIMBORNE PUBLISHING LIMITED SEQUOIA HOUSE 398a RINGWOOD ROAD FERNDOWN DORSET BH22 9AU Books are normally sent within seven days of receipt of order but please allow 28 days for delivery more for overseas orders Please check price and availability see latest issue of Everyday Practical Electronics before ordering from old lists For a further selection of books see the next two issues of EPE Tel 01202 873872 Fax 01202 874562 E mail dbs wimborne co uk Order from our online shop at www epemag co uk BOOK ORDER FORM Fullname TRETEN AUOIBSSS Licinia decies meme ee IE Post code UA aean E Telephone No eeeseseese LI enclose cheque PO payable to DIRECT BOOK SERVICE for Please charge my card Card Number Card Security Code the last three digits on or just below the signature strip Please send book order codes Card valid from date Please continue on separate sheet of paper if necessary Everyday Practical Electronics August 2008 69 PCB SERVICES Printed circuit boards for most recent EPE constructional projects are available from the PCB Service see list These are fabricated in glass fibre and are fully drilled and roller tinned Double sided boards are NOT plated through hole and will require vias and som
89. all specified components incorporating into existing e Just 50 x 50 x 15mm 0 equipment and is supplied short form with PCB and specified components Wind Powered Generator plus PCB standoffs Experimenters Kit for mounting a KJ 6696 15 95 post amp packing e 15VDC required l2 24V High Current Motor Learn all about this green energy i source and the mechanics of wind a Fa EE Speed Controller Kit generators It is supplied in kit form Three Stage FM Transmitter KC 5465 23 25 post amp packing so you get to assemble the whole thing KJ 8750 6 50 post amp packing Want to control a really big DC motor This design will before you start learning about how it This is a Three Stage radio transmitter that is so stable you control 12 or 24VDC motors at up to 40A continuous The works could use it as your personal radio station and broadcast speed regulation is maintained under load so the motor Approximately 300mm tall all over your house Great for experiments in audio speed is maintained even under heavy load It transmission Includes a mic PCB also features automatic soft start fast with overlay and all other parts s hausan aid hee peg e Requires 9V battery not included 3 e ED dos Ra in kit 3 a ns amp overload warning buzzer anda solar Car Kit i E a low battery alarm All control tasks KJ 8920 7 25 po
90. annel 4 HD remains exclusive to Sky also for an unspecified time We are talking to others says Lindsay Davis James Atkins Freesat s Trade Marketing Manager explains that ITV HD exclusivity means the service is a red button service accessed through MHEG interactivity options displayed on screen Freesat has its own seven day on screen electronic programme guide Freesat s EPG looks very similar to the Freeview EPG with similar text news 8 and information but access is much faster thanks to greater bandwidth Michael Grade Executive Chairman ITV plc promises An unrivalled line up of premium football including the FA Cup England internationals and UEFA Champions League from next season Although Sky and Freesat will share some transmission feeds the EPGs are different so Freesat viewers will not see Sky programmes listed whereas Sky Freesat viewers see a list of the programmes they could watch if they paid HD receivers Receivers from Alba under the Bush Goodmans and Grundig names will be available in SD and HD versions Humax is offering an HD box and Panasonic launched an HD Freesat IDTV in June Contrary to misleading statements made at the press launch none of the boxes has a phone socket but all have an ethernet port Viewers will be encouraged to plug in with the promise of exciting services such as IPTV in the future Prices start from around 50 for an SD box and 120 for H
91. apply online at www lektronix net about careers Everyday Practical Electronics August 2008 Learn About Microcontrollers P928 PIC Training Course 164 The best place to begin learning about microcontrollers is the PIC16F627A This is very simple to use costs just 1 30 yet is packed full of features including 16 input output lines internal oscillator comparator serial port and with two software changes is a drop in replacement for the PIC16F84 Our PIC training course starts in the very simplest way At the heart of our system are two real books which lie open on your desk while you use your computer to type in the programme and control the hardware Start with four simple programmes Run the simulator to see how they work Test them with real hardware Follow on with a little theory Our PIC training course consists of our PIC programmer a 306 page book teaching the fundamentals of PIC programming a 262 page book introducing the C language and a suite of programmes to run on a PC The module uses a PIC to handle the timing programming and voltage switching Two ZIF sockets allow most 8 18 28 and 40 pin PICs to be programmed The programming is performed at 5 volts verified with 2 volts or 3 volts and verified again with 5 5 volts to ensure that the PIC works over its full operating voltage UK orders include a plugtop power supply P928 BU PIC Training amp Development Course comprising Enhanced 16C 16F and 18F
92. ard to trigger an external mains rated relay That done check the corner hole sizes these should all be 3mm in diameter In addition the holes for the relay pins and the screw terminal blocks must be large enough to accept these parts Once all the hole sizes are correct begin the assembly by installing the resistors Table 1 shows the resistor colour codes but it s a good idea to check them using a digital multimeter just to make sure Next install the diodes and the optocoupler OPTO1 making sure they go in with the correct polarity Follow these with the capacitors transistors Q1 and Q2 the LED and the relay Again take care with the polarity of these components Transistors Q1 and Q2 come in iden tical TO 92 packages so be careful not to get them mixed up Transistor Q1 isan NPN BC549 type while Q2 is a PNP BC327 The circuit won t work if you transpose them or install them the wrong way around As mentioned previously you can use either a 3 way screw terminal connector or PC mount spade connectors to make the external connections to the COM pole NO and NC relay contacts Use the spade connectors if the relay terminals are to carry currents in excess of 2A Finally install the 2 way pin header for link LK1 The link itself can be left out if you intend to trigger the board using a DCinput signal Alternatively install the link if you want delayed switch on and switch off for the relay or if
93. ass band pass and band stop Bessel Butterworth and Chebyshev op amp filters BOGOF Buy one get one FREE buy any Student Hobbyist CD ROM on THIS page and get one other also from THIS page FREE Offer ends October 31 2008 ELECTRONICS CAD PACK PCB Layout Electronics CADPACK allows users to design complex circuit schematics to view circuit animations using a unique SPICE based simulation tool and to design printed circuit boards CADPACK is made up of three separate software modules these are restricted versions of the full Labcenter software ISIS Lite which provides full schematic drawing features including full control of drawing appearance automatic wire routing and over 6 000 parts PROSPICE Lite integrated into ISIS Lite which uses unique animation to show the operation of any circuit with mouse operated switches pots etc The animation is compiled using a full mixed mode SPICE simulator ARES Lite PCB layout software allows professional quality PCBs to be designed and includes advanced features such as 16 layer boards SMT components and an autorouter operating on user generated Net Lists ROBOTICS amp MECHATRONICS Case study of the Milford Instruments Spider Robotics and Mechatronics is designed to enable hobbyists students with little previous experience of electronics to design and build electromechanical systems The CD ROM deals with all aspects of robotics from the control s
94. assembly The PC board assembly can now be completed by installing the 78L05 regulator REG1 transistors Q1 to Q4 the two ICs and LED5 MOSFETs Q1 to Q4 and REGA all come in 3 pin TO 92 packages and must be orientated as shown don t get them mixed up Similarly the two ICs both CMOS devices must be correctly oriented Be sure to observe the usual pre cautions when handling the CMOS devices ie use an earthed soldering iron make sure you re not carrying a charge yourself avoid touching the pins and solder the supply pins to the board first pins 7 and 14 for IC1 and pins 8 and 16 for IC2 The green LED LED5 is fitted to the board at full lead length with its longer Everyday Practical Electronics August 2008 Constructional Project INPUT 5 RELAY 1 SOURCE OUTPUTS AUDIO 1 L AUDIO AUDIO R AUDIO RIGHT RIGHT COMP COMBO UE RELAY 5 CONI 77 COMP VIDEO ene VIDEO pow et a m cs dl AUDIO CONNECTOR EARTH ONLY VIDEO CONNECTOR EARTH ONLY CONNECTORS eH pcc iE amp RELAY CONTACTS FOR INPUT SOURCES tace 2 amp 3 NOT SHOWN Ed 1 TNEI L Rie LEDS 2N7000 SOURCE gt RELAY 4 A9 AUDIO LEFT A DGS AUDIO RIGHT COMP eS Oae RELAY 8 VIDEO D1 D5 1N4004 B l A K S VIDEO E gt i D5 12V DC REG1 78L05 12V K Go A INPUT GND 100nF 10pF ma 2200p F CONI1 f j pad Sla S2gh Sud S4u u Je A 5 5 Qus jJ SEL SEL2 SEL3 SEL4 1000 IC1
95. ation amp stable temperatures IUE tem erature range of 150 480 C ow voltage tron with Silicone cable Supply 240V Iron 24V 48W Model 167 570 52 23 Digital Multimeter Model 121 120 Price 11 47 A highly featured digital multitester for professional use Offers 30 ranges and 8 functions including temper ature capacitance diode continuity and hFE measure ment Large 3 5 digit LCD display with automatic po larity indicator Supplied with shrouded test leads K type temperature probe and shock proof rubber holster Technical Spcarcanons DC voltage 200mV 1000V 0 596 AC volts 2V 700V 0 8 DC current 2mA 20A 41 2 AC current 200mA 20A 1 8 esistance 200 Ohms 20M Ohms 0 8 Capacitance 2000pF 20uF EAD Temperature 0 C 1000 C 1 596 Frequency 20kHz 196 Max TENES 1999 Power supply 9V PP3 battery Dimensions 88 x 173 x 40 mm real T kellect Sound amp Lightin PCB Production Processing Equipment We carry a large range of the photographic amp chemical rocessing equipment for PCB production a full list with ull technical specifications is available in our catalogue or vist our web site V Exposure units 2 x 8W Tubes 6 min timer 229 x 159mm working area Model 332 002 95 00 4 x 15W Tubes 7 min timer 330 x 260mm working area Model 332 004 207 99 Chemical Processing Low cost plastic tray 2 90
96. automatically stored to disk for future recall each time the program is run Mains test Once the zero position has been set plug in a mains powered unit that draws a known current say a 100W table lamp and switch it on On the main PC screen click the volt age setting radio button for 230V or 110V to suit the known standard AC mains voltage RMS This setting is also stored for future recall Incoming above zero current waveforms will now be plotted to screen at an appropriate position above the zero point Towards the top of the PC screen is a text box marked W Ref into which you type the reference current consumption 42 eg 100W of the unit being moni tored Just type the value do not press lt Enter gt on the keyboard With the incoming values now being received consistently click on the Set Mult button on the screen The value is stored to disk for future recall and represents the screen position that waveforms in respect of eg 100W consumption should take Other consumption values are plotted at similarly related screen positions both as waveforms and in the bargraphs No further setting up is required You will notice on the main screen Fig 1 that the green labels at the bottom of the screen display numerical values related to incom ing data They were placed there for the author s development use and may be ignored It may be noted though that the SubSmpl count value will normally be showin
97. ay be regarded by the inexperienced as the ultimate answer to all electronic circuit design This is most definitely not the case All that a microcontroller will do is assist in using software commands to replace a fair number of operations for which many electronic components would otherwise be needed It cannot substitute for all electronic requirements There are also situations in which a microcontroller can be used but it 1s not necessarily desirable that it should What you will discover as you get further into programming is that the act of programming a PIC to replace a given number of logic chips can take far longer than if you were to design a circuit that performed the same function but only used such chips Unless you actually want to get a PIC to do something because it can and you see it as a challenge always ask yourself if the additional development time is worth it in order to save a chip or two 49 Software writing generally When writing software you will find much frustration through the inability to immediately see the bug in a program routine Eventually though you will spot it and the relief and exhilaration of at last getting that part to work is enormous In that frame of mind you will move on to writing the next sub routine with the utmost confidence and anticipation of not making a mistake on this one Would that it were so You can and you will make e NEWSAGENT mistakes But the ultimate
98. ayer Multilayer Relay 1 humidity fo LIN boards amp d rainfall a s E Free 7 Free mum sae co Ware 1 or Freephone D i 353 0 61 diee From 59 NIE 0800 3898560 BRA 4 Learn more at WWW audon co uk GE uae AED E Hs SEA omoes tune roc E i r NN ih 3 Simply send your files SPP QR Electronics and order ONLINE www audon co uk 44 0 115 925 8412 Fax 44 0 115 925 9757 Everyday Practical Electronics August 2008 45 Teach In 2008 Part Ten Examining a program s construction a game of Dominoes plus LCD symbol creation JOHN BECKER E have now reached a point where it is worthwhile discussing a practical full length program and part of its construction It illustrates a variety of concepts to which you have been introduced earlier plus futher information on alphanumeric LCD use with particular regard to creating your own display characters The program is for the author s Mock Dominoes self entertainment game previously unpublished in which the user plays against a PIC with moves displayed on an LCD The circuit diagram and breadboard layouts are shown in Fig 10 1 and Fig 10 2 The program is too long to be shown here and only the occasional extracts will be discussed The full program is in TeachInXOl asm available in the usual way from our website via www epemag wimborne co uk Description Referring to Fig 10 1 the circuit consists of the PIC and LCD on the Teach In 2008 Demo PCB
99. based on the sensed temperature Its sensor can work over the range of 0 C to 245 C making it useful for monitoring engine oil engine coolant and transmission oil temperatures as well as intercooler and inlet air temperatures Note that link LK1 to the left of the relay must be moved to the H L position and diodeD3 circled reversed i in orientatic onif FFRnMIT CIIS DIG Ta rre mp oe a a Pu e Operate electric radiator fans e Trigger over temperature warning light alarm e Operate amplifier cooling fans e Operate an intercooler water spray or fan e Operate a brake cooling water spray e Reduce turbo boost when intake air board Conversely to detect a falling temperature link LK1 is moved to its al ternative H L position and diode D3 s orientation is reversed Easy huh When assembling the PC board be sure to insert the polarised compo nents the correct way around These parts include the diodes IC LED TOOuF 10pF THERMISTOR JB temperature is high transistor voltage regulator and electrolytic capacitors During construction follow Fig 2 closely to avoid making mistakes Thermistor The thermistor is of the bare de sign ie it s not potted in epoxy or mounted inside a brass fitting If you want temperature detection to oc cur very quickly ie if you want the REVERSE D3 IF LINK LK1 IS IN H L POSITION Fig 2 this layout diagram shows where each of
100. be another faint click as that channel s relays activate and the previously activated relays switch off Finally press the remaining two buttons in turn and check that you get the same response If so your 4 Channel A V Selector is working correctly and you can now secure the top half of the case to the bottom us ing the four M3 x 25mm countersink head screws provided Troubleshooting There s not much in this circuit so there s very little to go wrong How ever in the unlikely event that prob lems do occur they re most likely to be caused by fitting polarised parts the wrong way around If the whole project is dead the odds are that you ve either fitted diode D5 the wrong way around or swapped the connections to the 2 5mm plug on the 12V power lead from the plugpack or battery Simi larly if the circuit seems to work correctly but one of the five LEDs doesn t light when it should its leads have probably been transposed These are almost the only things that could be wrong apart from poorly made solder joints or even joints you ve forgotten to make EPE Reproduced by arrangement with SILICON CHIP magazine 2008 www siliconchip com au 17 Account No 10565 3000 SERIES 35000 SERIES 2000 SERIES VISIT USB Connected High Speed PC Oscilloscopes UNAM u ATARI PicoScope 5000 Series 250 MHz bandwidth The No Compromise 1 GS s real time sample rate
101. cables for the electronics enthusiast it is probably their novelty value that makes them worthy of exploration Fibre optic cables provide an innovative interesting alternative to electric cables but in most cases they also represent a practical approach to the problem This book provides a number of tried and tested circuits for projects that utilize fibre optic cables The projects include Simple audio links F M audio link P W M audio links Simple d c links P W M d c link P W M motor speed control RS232C data links MIDI link Loop alarms R P M meter All the components used in these designs are readily available none of them require the constructor to take out a second mortgage Order code BP374 5 45 138 pages 132 pages STARTING ELECTRONICS THIRD EDITION KEITH BRINDLEY A punchy practical introduction to self build electronics The ideal starting point for home experimenters technicians and students who want to develop the real hands on skills of electronics construction A highly practical introduction for hobbyists students and technicians Keith Brindley introduces readers to the functions of the main component types their uses and the basic principles of building and designing electronic circuits Breadboarding layouts make this very much a ready to run book for the experimenter and the use of multimeter but not oscilloscopes and readily available inexpensive components makes the practical work ac
102. ce because signal quality is poor or non existent in 25 of the country can now get all the Freeview programmes plus some extra channels and HD through a dish antenna See www freesat co uk In a thinly disguised snipe at Sky which offers its own Sky Freesat service but uses it as a marketing tool to sell subscriptions Emma Scott managing director of the new Freeview Freesat service promises A guaranteed free service for a one off payment and no follow up hassle calls The Freesat programme line up starts with 80 TV and radio channels including all the BBC and ad supported channels currently on Freeview DTTV with the addition of a few extra movie and news channels including Movies4Men and Al Jazeera English Around 200 Freesat channels are promised by the end of the year the contracts are signed and channels added at around 20 per month Regional variations Viewers will be able to see the regional variations of BBC and ITV programmes normally only broadcast locally on terrestrial masts During initial box set up the viewer enters their home postcode and the box then defaults to the local region programming There is no room for HD on DTTV and Freesat already carries one HD channel from the BBC and the promise of another from ITV within a few weeks The ITV HD channel claim Emma Scott and Commercial Development Director Richard Lindsay Davis is exclusive to Freesat for an unspecified time while Ch
103. cessors architecture bus systems and their arithmetic logic units Sections on Boolean Logic and Venn diagrams displays and chip types have been expanded in Version 2 and new sections include shift registers digital fault finding programmable logic controllers and microcontrollers and microprocessors The Institutional versions now also include several types of assessment for supervisors including worksheets multiple choice tests fault finding exercises and examination questions ANALOGUE METERS Analogue Filters is a complete course in designing active and passive filters that makes use of highly interactive virtual laboratories and simulations to explain how filters are designed It is split into five chapters Revision which provides underpinning knowledge required for those who need to design filters Filtrer Basics which is a course in terminology and filter characterization important classes of filter filter order filter impedance and impedance matching and effects of different filter types Advanced Theory which covers the use of filter tables mathematics behind filter design and an explanation of the design of active filters Passive Filter Design which includes an expert system and filter synthesis tool for the design of low pass high pass band pass and band stop Bessel Butterworth and Chebyshev ladder filters Active Filter Design which includes an expert system and filter synthesis tool for the design of low pass high p
104. ches the desired trig ger level then turn set point pot VR1 until the Temperature Switch just turns on The turn off value will be set by the hysteresis pot VR2 If you want the turn off value to be close to the turn on temperature set VR2 fully anti clockwise If you want the turn off temperature to be much lower adjust VR2 further clockwise The other way of setting the trip point is to make some measurements on the bench Table 1 shows typical NTC ther mistor resistance values for a range of 34 temperatures The thermistor is 10kQ at 25 C and falls to 34 5Q at 245 C Table 1 also shows the expected voltage across the thermistor at each temperature value assuming the regu lator output is at 8V If the regulator voltage is slightly different to this then the value will need to be scaled accordingly For example ifthe regulator output is 7 8V then the output voltage will be the value shown multiplied by 7 8V all divided by 8V You can measure the regulator s output voltage by using a multimeter to probe the righthand terminal of the regulator with the PC board orientated as in the component layout diagram Fig 2 and photos Connect the other probe of the mul timeter to ground 0V Make sure that you don t slip with the multimeter probe and short circuit the regulator When VR1 is adjusted so that a particular voltage shown in Table 1 can be measured on its wiper mov ing terminal the switch will trip at
105. chnique with a heated de soldering tool such as available from Rapid Electronics for less than 20 00 see their stock code 85 0900 Most components can then be removed easily with a pair of thin nosed pliers or for ICs I use an extraction tool like that available from Rapid stock code 22 0320 for less than 1 00 2 Use a hot air gun to melt the solder and air blast the joints as described above I have a temperature controlled gun with a small nozzle and ensure that it is not applied for too long on any one area Again take care of molten solder splashes and use more conventional techniques to remove as much solder as possible prior to air blasting Air blasting also cleans out the plated through holes nicely to allow replacement of the part Both sides of the PCB will need a good brushing to remove the fine just It s a bit wobbly Great care is needed it s not something I d want to do too often The plastic spectroscope has to physically rest against the lens haven t scratched it so far Some photographic expert out there is bound to have a better idea as to how to accomplish this Borisalso responded on the CZ suggesting Derek browsed http en wikipedia org wiki Spectrometer MIDI Drum Kit Dear EPE I refer to the MIDI Drum Kit Pt4 March 08 issue page 65 the box red background bottom right corner headed Macintosh Computers mentions the Yamaha UX96 USB to MIDI converter Unfortunately it is no
106. coars ad eis 5 50 greater than 1kg or gt 30 Tyne amp Wear Cheques Postal orders payable to NE30 4PQ wis ESR Electronic Components Ltd PLEASE ADD CARRIAGE amp VAT TO ALL ORDERS Tel 0191 2514363 Fax 0191 2522296 F sales esr co uk WEVERYDAY PRACTICAL ELEC THE UK S NO 1 MAGAZINE FOR ELECTRONICS TECHNOLOGY amp COMUTER PROJECTS TRONICS 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 enquiries epemag wimborne co uk Web Site www epemag co uk EPE Online downloadable version of EPE www epemag com EPE Online Shop www epemag wimborne co uk shopdoor htm See notes on Readers Technical Enquiries below we regret technical enquiries cannot be answered over the telephone Advertisement Offices Everyday Practical Electronics Advertisements Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Phone 01202 873872 Fax 01202 874562 w ted Email stewart kearn wimborne co uk Qnfestminste Bn toutes an ec teu mm e pa together Ph io es ond deb VOL 37 No 8 AUGUST 2008 igne go vw G0 wong suppl ox Climate chang owtugi aie golutions Editor MATT PULZER ety iy stand iM Consulting Editors DAVID BARRINGTON ous wevell JOHN BECKER to Lecture 9 tke ig well wor Subscriptions MARILYN GOLDBERG ee d General Manager FAY KEARN Editorial Admin
107. ctical Electronics August 2008 TL 500 Temperatur Logging System AREX AREXX Engineering hre i Array TET rmn AREXX Wie CE ro hare BES T EEE ch pcakdesp levee wearer Bj dep M mnes The TL 500 Temperature Log ging System can be used inside and outside all locations where a registration of tempera ture information is needed and is also suitable for industrial use The TL 500 System contains a software application a recei ver and two wireless tempera ture sensors Separate sensors are available for temperature humidity and CO2 measurement Thenew temperature data of all sen sors every 45 seconds is passed on wirelessly USB to the PC for further processing Forthis a visua lisation programis at your disposal Including Messenger Software to send temperature messa ges by email With Email to SMS service thesemessagescanalsobe received by SMS UK Distributor RAPID Electronics At least 50 sensors can be connected More information AREXX Engineering The Netherlands T 31 38 4542028 F 31 38 4524482 info arexx nl www arexx com 55 Fig 4 Analysis of the LED multiplexer circuit The resistor and V drops in the circuit in Fig 3 ensure that the emitter is at least a volt or so below the supply so the base collector junction will be reverse biased and the transistor will be in the forward active region Reducing the base resistor to try to produce a h
108. ction W time out alarm and a Lu short delay before the alarm sounds A E Supplied with PCB and electronic components projects Book measures 205mm x mount devices on a PCB only 5mm wide The probe 275mm includes a pulse stretcher that will let you see very short pulses and a latch function to hold infrequent pulses Kit includes PCB and all specified electronic components including pre programmed PIG Short Circuits Book Volume Il You ll need to add your own case BJ 8504 4 00 post amp packing and probe 2 cigar Ballpoint pen anda Once you have the basic skills and knowledge from needle work well tackling Short Circuits Vol 1 you can now have some real fun With this book and associated project packs available separately you can make such things as a mini strobe light police siren mini organ a Subwoofer Controller Kit Using this kit to control your external speaker and KE 4711 3 70 postage amp packing radio transmitters an sub amplifier can give you loads of bass without taking This unit is a two transistor two stage transmitter that has FM radio even a up much space The kit has all the features you could the benefits of being VERY COMPACT Knight Rider scanner ll want including low and high pass filters parametric e The Jaycar kit contains PCB 9V battery and all All components are equaliser and auto turn on for external equipment The components and fully described and
109. cular When pushbutton S1 is re leased C2 discharges through R1 IClc and ICld with TR2 form a posi tive edge triggered monostable timer so k D1 1N4007 a ZSEE ie a that when pin 8 goes low TR2 ceases to conduct This means that TR3 s gate goes high and TR3 conducts thus activating so lenoid L2 for a fraction of a second D2 is again provided to suppress back EMF Unless a large battery is used for B1 Cl is needed to provide the whack required for solenoids L1 and L2 Non polarised capacitors are recommended for C2 to C4 to set aside worries about polarity However polarity is shown in the circuit in case the constructor is only able to TR3 ICid 2N7000 BUZ11A 4093 Fig 1 Circuit diagram for the Universal Ding Dong 52 Everyday Practical Electronics August 2008 locate electrolytic capacitors of this value If the pulses which activate L1 and L2 are not sufficiently long the values of R2 and R3 may be increased and vice versa If TR1 and TR3 cannot be found rough equivalents may be used Equivalents should be chosen with care for TR2 since this is a miniature MOSFET While an NPN bipolar transistor could be used here the value of R4 should then be reduced to say 47k 2 thus increasing power con sumption on standby Ideally solenoids L1 and L2 are 12V push action types or pull action types which have a thrust pin at the back However plain pull action types should work if they a
110. d so far the values are shown numerically The facility to show them as traditional dots or pips has been provided The choice of display type can be made when switch S1 is pressed and held pressed while the PIC s power SWAP PLAYER is turned on The selection is stored in the EEPROM for use the next time S1 is pressed when the power is switched on The choice of display type alternates on each such occasion The value is always read from the EEPROM each time the program is switched on The LCD has 16 bytes available in its character generator which can be programmed to hold symbols other than those normally provided These are held in LCD locations O to 15 see Table 3 in the Using Alphanumeric LCDs article referred to previously in the series for a list of the character generator s symbol locations Display command values between O0 and 15 cause the user generated symbols to be displayed in the same way as when you use values to access symbols at the normal character locations 32 upwards Throughout the Teach In series up to this point you have been displaying the LCD s alphanumericcharacter viathe Display Address command that is part of the LCD initialisation routine To write your own symbols into the Character Generator RAM locations 0 to 15 the CG RAM use command must first be given via LCDLIN The datasheet shows all the commands available for a standard 2 line alphanumeric LCD Th
111. e software which can be downloaded free from the EPE website Without Joe s program the Mains Monitor source code will not func tion when run and will crash PC communication is at 2400 Baud and this rate is built into the software The COM port used by the PC may be selected as COM1 or COM2 There are radio buttons provided on the main PC screen for selec tion The chosen port value is stored for future recall It may be changed at any time when the program is not actually recording On first running the PC software the opening screen will be similar to that shown in Fig 1 but without Constructional a FW uw s a sm me mm mm i F B M z a hs Component layout on the prototype mains monitor board The Hall effect transducer X3 is just below the mains transformer and the transmitter TX module is far right The 8 pin DIL socket at the centre bottom edge of the board is for a 4 way DIL switch see text Fig 7 Example of the LCD screen shortly after starting waveforms of course The COM port selection will be seen at the top right of the screen as shown in Fig 1 select the COM Port required The initial default is COM1 Recording monitored data In the initial testing stages switch on S3 so that the PIC s clock counter value is automatically transmitted every second Fig 8 Example of the LCD screen during monitoring On PIC switch on or reset the LCD if connected will fo
112. e CG RAM selection command is b LAAAAAAA where the A s indicate the CG RAM address selection The selection is made by setting the LCD address you want to write to into W and then calling LCDLIN When writing symbol data to the CG RAM eight writes to it are required to form a complete symbol The CG RAM address is automatically incremented with each write thus you only specify the first address to which you wish to start writing RANDOMISE pono 00000 00000 00000 00000 00000 00000 00000 00000 48 00000 00000 00000 00100 00000 00000 00000 00000 00000 10000 00000 00000 00000 00001 00000 00000 00000 10000 00000 00100 00000 00001 00000 00000 00000 10001 00000 00000 00000 10001 00000 00000 00000 10001 00000 00100 00000 10001 00000 00000 Fig 10 4 LCD maps for the Domino faces 00000 10001 00000 10001 00000 10001 00000 00000 Symbol creation To create a symbol you draw a squared map of the pixels that make up the symbol five horizontally and eight vertically The maps required for the seven domino faces are shown in Fig 10 4 Note that line 8 is reserved for underline cursor use the main character symbol is in the first seven lines Below each map are the logic values of each line A 1 represents a pixel which is to become active and 0 for one which is not The values are shown in 5 bit binary logic To suit them for use in the PIC p
113. e are two minor bugs in the program The first is that when selecting the first tile pair on LCD line 1 it is sometimes necessary to move the cursor to the second pair and then back again before the first pair can be selected Second the cursor position sometimes skips a pair to the next one Can you fix these bugs A few helpful notes During this series we have provided you with sufficient knowledge about the PIC16F628 to enable you to now write your own programs for your own purposes You should be aware though that there are various aspects of the PICI6F628 that we have not described Many of them the author has never used In due course you may find aspects that are useful Armed with knowledge about the PICI6F628 you now have a pretty good understanding of the basic requirements for programming any PIC microcontroller It should be strongly noted however that there are other families of PICs in which some aspects are treated differently to the PIC16F628 Whatever PIC you choose to use always obtain its datasheet before using it As said previously datasheets can be downloaded free from Microchip s website Always remember that users of our Chat Zone are incredibly knowledgeable about many things and it s always worth asking there about any matters which may puzzle you Programming To the uninitiated it may seem that a software programmer simply sits down and writes all the commands in a single operation If
114. e components soldering both sides All prices include VAT and postage and packing Add 1 per board for airmail outside of Europe Remittances should be sent to The PCB Service Everyday Practical Electronics Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Tel 01202 873872 Fax 01202 874562 Email orders epemag wimborne co uk On line Shop www epemag wimborne co uk shopdoor htm Cheques should be crossed and made payable to Everyday Practical Electronics Payment in sterling only 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 for delivery overseas readers allow extra if ordered by surface mail Back numbers or photocopies of articles are available if required see the Back Issues page for details WE DO NOT SUPPLY KITS OR COMPONENTS FOR OUR PROJECTS Please check price and availability in the latest issue A large number of older boards are listed on and can be ordered from our website Boards can only be supplied on a payment with order basis PRO ECT TITLE APRIL 07 PIC Polyphonium LED Display Interface Students Amp Amplifier PSU Star Power MAY 07 Bass Extender Caravan Lights Check JUNE O7 Energy Meter Main Board 616 Display Board 617 3V to 9V Converter PCB plus TL499A IC 620 4 chip Bat Sonar 621 JUY 07 MiniCal 5V Meter Calibration Standard Lead Ac
115. e music or video files unless they leave their machine running overnight a throwback to the dark dial up days In the writer s case a theoretical 8Mbps tariff 2Mbps actual via Tiscali ADSL was yielding a miserable 20 or 30kbps download at peak times This maddening performance coupled with the higher monthly tariff compared with new customers only rates meant it was finally time for a change In the UK the procedure of switching broadband ISPs involves cancelling the existing service and obtaining a MAC Migration Authorisation Code from them to pass to the new provider This must be done within a set timeframe or it automatically times out In Tiscali s defence after cancelling the service the process was 100 troublefree The MAC code was emailed within the hour confirmed in writing and the changeover took just seven days The new ADSL logins were duly delivered by the new ISP Swift Internet and configured in the router once the old service went down The difference was immediately noticeable particularly with large files that now download at a consistent 285kbps roughly ten times faster than before Remember that ADSL services are contracted for typically 12 months so you may not be able to move if you are locked into your current contract When cancelling you will lose any email or web addresses that are tied to your current broadband service Apart from switching supplier via a MAC code you could also
116. e your own software Stand alone test func tion that outputs all 512 channels at a time with adjustable levels Supplied with case lead amp CDROM K8062 Kit VM116 Assembled Remote Control Transmitter For use with the K8057 VM109 2 channel RF receivers Generates unique 32 bit code more than 1 000 000 000 unique codes code can easily be changed for safety purposes choose continuous or burst transmission fh LED indicator K8059 Kit 46 95 49 95 8 95 0191 2514363 Tel Cullercoats 5 50 greater than 1kg or gt 30 Fax 0191 2522296 Tyne amp Wear m ues Postal orders payable to sales esr co uk NE30 4PQ EJ visa ESR Electronic Components Ltd Station Road Bl 2 VELLEMAN is o major European distributor of high quality electronic products They have been trading for more than 35 years and operate from Gavere Belgium With a network of over 17 000 dealers in more e are now able to offer you the complete range cf their electronic kits modules and PC based development products If you would like a copy of the latest 80 page catalogue please phone fax or email your name and address www esr co uk velleman Remote Control Receiver Two relay contact outputs for use with K8059 and VM108 two chan nel RF codelock transmitters tog gle or pulse function selectable per output can learn a unique 32 bit code from the transmitters store up to 31 transmitters LED indicators for outputs a
117. ecified setting of STARTER bit O ie bit O is used as a flag Remember that registers can can take on any random value at power switch on The value 0 represents you whereas 1 represents the PIC Assuming that the starter is the PIC it scans its available tile values until it finds a double sided face in a normal domino game the starter usually chooses the highest value of double not so here for the PIC The choice of double is displayed on LCD line 2 at the left The byte value is also stored to an incrementing storage register area commencing at LCDStore0 in Bank 1 at h CO This stores all user or PIC selected choices in order as the game progresses When writing the program the author ensured that intentionally allocated registers via the EQU instruction started at addresses which would not cause an overlap in register allocation He then only needed to specify the first address in each group and did not need to name each address in that group The use of commands FSR and INDF then allows ready access to any address in a group Note in the ASM file how the value placed into FSR explicitly specifies the Bank as well as the register within it ORing the register value with 128 for Bank 1 omitting the 128 OR for Bank 0 Switch selection When it is your turn to make a tile selection you use switch S2 to move the highlighted double cursor across the double byte values Pressing S1 moves the cursor back A single
118. ecreases The Darlington introduces an extra V drop reducing the 2 2 in the formula to 1 5 so we have I 1 5 10 470n p If 8 5000 we get LED 149mA 2 LEDs 147mA 3 LEDs 146mA 8 LEDs 140mA Roughly the same current but considerably less variation with the number of LEDs Our analysis has not attempted to calculate exact values for the real LED multiplexer we have assumed typical values rather than trying to use specific ones Knowing the exact transistor gains is very difficult anyway The BC548s should have a higher gain than 100 but their gain drops rapidly for collector currents above 100mA This would exaggerate the dimming problem Our analysis has confirmed the findings reported by John and hopefully provides some insight into transistor switch operation EVERYDAY PRACTICAL ELECTRONICS Stewart Kearn on 01202 873872 or email stewart kearn wimborne co uk Everyday Practical Electronics August 2008 fires titre RIG nl Mig TAULE Hibbett fy Our periodic column for PIC programming A its More on l Oport expansion Te month we finish off last month s coverage of I O port expansion with a practical demonstration interfacing a PIC to a panel of 1024 LEDs arranged in a 32 by 32 grid While this is only a theoretical discussion the author didn t sit down and wire up over a thousand LEDs the software has been fully developed and prototyped with a few tens of LEDs to
119. ed A and K on Fig 2 ie on either side of each pushbutton switch That done cut four 25mm lengths of tinned copper wire and bend each one into a U shape with the arms about 5mm apart These should then all be fitted in the positions shown for the connections to switches S1 to S4 Solder their ends to the pads under neath then cut each U shaped loop at its top centre and straighten the ends to form a pair of wires ready to connect to the switch lugs Next cut five 35mm lengths of yellow hookup wire and another five 35mm lengths of black hookup wire and remove 4mm of insulation from both ends of each piece That done solder one end of each of these wires to the PC board as shown in Fig 2 these are later used to connect the composite video connectors CON12 to CON16 to the PC board The eight mini DIL relays are next on the list followed by the 12 resistors the two 100nF multilayer monolithic capacitors small and usually blue and the two MKT polyester capacitors These parts are all non polarised so they can be fitted either way around By contrast the 2200uUF and 10uF electrolytics are polarised so be sure they go in the right way around Fit these now then install diodes D1 D5 again making sure they are correctly orientated Diodes D1 to D5 have their cathodes K indicated by a band on their body The LEDs havea flat on their package against the cathode lead also the anode A lead is longer Final board
120. ed temperatures or a low hysteresis to keep tighter control the choice is yours Third the sensor used in this design is good for temperatures up to 245 C This means you can monitor engine oil or auto transmission oil temperature or site the sensor near the brakes to trigger cooling sprays In other words apart from exhaust gas and cylinder head temperature you can trigger the switch with anything on the car that s hot or cold Finally you can configure the sen sor so that it reacts very quickly to temperature changes Construction The Temperature Switch is simple to build but you should make one decision before starting construc tion Will you be using it to detect a temperature that is rising to the trip point or falling to the trip point The Temperature Switch can be configured to work either way but if you know which way you re going you won t have to make changes later on The detection of a rising temp erature will be the more common application for example turning on a warning light or cooling fans when the temperature gets too high But if you want something switched on as the temperature falls for example activating a warning light when the outside temperature drops below 3 C to warn of the possibility of black ice on the road then the Temperature Switch needs to be configured for a falling temperature So what changes are necessary for the differing configurations They re simp
121. ee website or join our mail Newsletter for all the latest news Bipolar Stepper Motor Chopper Driver New bipolar chopper driver gives better performance from your stepper motors It uses a dual full bridge mo tor driver based on SGS Thompson chips L297 amp L298 Motor current for each phase is set using an on board potenti ometer Can handle motor winding currents of up to 2 Amps per phase Operates from a DC supply voltage of 9 36V All basic motor controls provided including full or half step ping of bipolar steppers and direction control Synchroniseable when using multiple drivers Perfect for desktop CNC applications Kit Order Code 3187KT 29 95 Assembled Order Code AS3187 39 95 Shaking Dice This electronic construction kit is great fun to build and play with Simply shake and watch it slowly roll to stop on a random number Kit Order Code VMK150KT 9 95 Running MicroBug This electronic construc tion kit is an attractive bright coloured bug shaped miniature robot The microbug is always hungry for light and travels toward it Kit Order Code VMK127KT 9 95 Video Signal Cleaner Digitally cleans the video signal and removes un wanted distortion in video signal In addition it stabi lises picture quality and luminance fluctuations You will also benefit from improved picture quality on LCD monitors or projectors Kit Order Code VK8036KT 19 95 Assembled Order Code VVM106
122. ent date eg Mainsmon12 15 2007 txt in order of month day of month and year Even if the PC program is halted and restarted data is concatenated to placed at the present end of the file The file name is automatically changed to a new file name follow ing a date change Even when the PC is run for the very first time an ap propriately named file is created To stop recording at any time click the Stop button previously marked as the Start button In point of fact the recording file is never open except when data is actually being concatenated to it so the program may be exited safely just by clicking on the usual X button at the screen s top right or the Quit button The screen s Clear Screen button is not normally used but can be clicked if the recorded waveforms become crowded during long term monitoring Recall screen Any named file can have its values recalled and displayed via the Recall Screen Click the same named button at the top right of the main screen to display it see Fig 9 There are four methods by which files can be viewed those relating to the current date a named date dates between two given dates and files since a given start date Any date that does not have a file asso ciated with it is simply ignored by the software it does not crash for such reasons The name of the last file processed is shown in the blue box at the top of the screen There are four text boxes associ a
123. enviable reputation for the best in technical excellence and customer service Due to the huge demand for our services and our future expansion plans we need to employ additional engineers at all our workshops to keep pace with the additional work we are receiving We are looking for English speaking Electronic Repair Engineers Electronic Repair Technicians and Electronic Component Level Repair Engineers in all the following locations Walsall UK Newry Northern Ireland Brno Czech Republic Do you have an interest in electronics Bridgend UK e Katowice Poland e Dubai UAE Have you any experience in the field of practical electronics Have you experience in Radio Television Home Electronics Does your hobby interest include electronics Are you willing to learn new tricks electronic engineering Do you want work in an exciting and challenging environment Do you have any experience with Machine Tool Systems PLC s Servo Drives Servo Motors Monitors VDU s AC Drives DC Drives Temperature Control Digital Electronics Analogue Electronics We offer a competitive salary and all the other benefits normal with a go ahead company 50 a Please Contact Mr Brian Stewart Group Technical Director Lektronix International Ltd Unit C1 Lockside Anchor Brook Ind Park Aldridge West Midlands WS9 8EQ United Kingdom For an application form please either Telephone 44 0 1922 455555 or
124. erature then has to fall before the fan switches off Fitting Fitting the Temperature Switch to a car is easy You need only provide an ignition switched power supply and earth OV and then install the thermistor where you want to sense the temperature For example if you are controlling a radiator cooling fan then you could place an electrically insulated tempera ture sensor on the top tank of the radia tor Or if you want the Temperature Switch to illuminate a warning light when engine or transmission oil gets excessively hot you could attach the sensor to the appropriate sump If you want just the warning light function you can remotely mount a high intensity LED within your line of sight just extend the wires that connect the LED to the PC board making sure that you keep the LED polarity correct If you want to turn a device on and off with the temperature switch you Table 1 Setting the trip point temperature 33 944 034 26 120 042 20 286 407 15 894 535 12 557 604 10 000 00 8023 382 6483 660 5275 206 4319 920 35959 5795 2950 420 2459 334 2061 059 1736 202 1469 774 1250 116 1068 105 9160557 789 791 683 278 993 599 517 244 452 462 397 143 349 731 208953 273 760 243 287 216 818 193755 173 601 155 936 140 416 126 739 114 656 103 954 94 454 00 999 78 458 71 718 65 679 60 259 55 384 50 991 47 023 43 435 40 183 922 2931 34 547 You can use this table to set the tri
125. es LCD or transducer X3 until the correctness of the 5V and 15V power supply lines has been proved Also check the supply line voltages after the respective named parts have been connected A variation of a few tens of millivolts in the supply line levels is acceptable It is best if the mains transformer is initially omitted and the circuit checked using a 15V DC power RalatsSmaisitioaeCanteniacesvodulle PC board code 680 Inter face available from the EPE PCB Service Small plastic case size and type to individual choice 16 pin DIL socket 9 pin D type connector female SK1 9 way D type connector lead with plug and socket Aerial wire see text multi strand connecting wire Nylon self adhesive PCB mounting pillars 4 off solder pins solder etc 40 Semiconductors 1 BC549 NPN transistor TR2 1 MAX232 RS232 serial interface IC6 1 78L05 5V 100mA voltage regulator IC7 1 AM HRR3 RS 433MHz receiv er module RF Solutions see text IC5 Capacitors 5 1uF 16V radial elect C15 to C19 2 100n ceramic 0 2in pitch C20 C21 Resistors 0 25W 1 carbon film 1 1kQ R17 1 10kQ R18 supply Only when everything has been checked should the trans former be inserted and connected to the mains The connections required for the AC mains are shown in Fig 5 Con nection to the PC from the RS232 interface via socket SK1 should be via 9 pin serial connectors and cable which s
126. es a complete introduction to the practical side of this fascinating hobby including the following topics Component identification and buying the right parts resistor colour codes capacitor value markings etc advice on buying the right tools for the job soldering making easy work of the hard wiring construction methods including stripboard custom printed circuit boards plain matrix boards surface mount boards and wire wrapping finishing off and adding panel labels getting problem projects to work including simple methods of fault finding In fact everything you need to know in order to get started in this absorbing and creative hobby Order code BP392 5 49 BUILDING VALVE AMPLIFIERS Morgan Jones The practical guide to building modifying fault finding and repairing valve amplifiers A hands on approach to valve electronics classic and modern with a minimum of theory Planning fault finding and testing are each illustrated by step by step examples A unique hands on guide for anyone working with valve tube in USA audio equipment as an electronics experimenter audiophile or audio engineer Particular attention has been paid to answering questions commonly asked by newcomers to the world of the vacuum tube whether audio enthusiasts tackling their first build or more experienced amplifier designers seeking to learn the ropes of working with valves The practical side of this book is reinforced by nu
127. eye takes several milliseconds to detect that the light has been turned off an effect that is referred to as persistence of vision The eyes rely on a chemical reaction to detect changes in light level and so we can switch off the light from one row of LEDs illuminate all the others and so long as we return back to this row quickly enough and turn it back on the eye will not notice This trick is how televisions and computer monitors work and also how LED Message Wands can display a message seemingly in the air We can apply the same trick Before we look at the circuit design we have to decide what kind of display update rate to use how quickly are we going to move from one row to another Oddly enough we have to be careful to not go too fast Even before we have written the software we know that it wil take a certain amount of time to turn the signals on or off Suppose for a moment that you could do it in 10us If you then moved immediately to the next row the LED would not be switched on long enough for our eye COLUMN 0 fact before we are turning it off and illuminating the next row of LEDs We have to provide a delay to allow sufficient time for the LEDs to show the information we have written to them and for that data to register on our eyes So what rate is best Ideally we should go as slow as possible but no slower Slow enough that the data has plenty of time to be visible but not so slo
128. first LED to light up is D1 When the current increases to around 10mA the voltage developed across resistor R3 is about 2V so the second LED bar D2 and D3 starts to light up At around 20mA the voltage across R4 has reached about 2V so the third LED bar D4 D5 and D6 starts to light up At around 30mA the volt age across R5 has reached about 2V so the fourth LED bar D7 to D10 starts to light up Finally when the current reaches around 40mA the voltage across R6 is about 2V so the fifth LED bar D11 to D15 starts to light up The total current consumption at 15V input is about 50mA For best results use LEDs with a forward voltage drop of 2V or less at 10mA and low internal resistance D1 TO D15 STANDARD LEDs SEE TEXT SEE TEXT Fig 2 Circuit diagram for the10V to 12V LED Voltmeter To fine tune the Zener diode voltages try varying the value of R1 but do not go below 100Q2 or above about 47kQ P A Tomlinson East Yorkshire ESR and Car Meter Measures capacitance ESR in circuit too Automatic controlled capacitor discharge _ Atlas DCA Model DCA55 Semiconductor Atlas SCR Model SCR100 Triac and Thyristor Analyser Auto lead identification Auto gate test current from 100uA to 100mA Atlas LCR Model LCR40 Automatic o piti Automatic part identification automatic ood X Buxton ipea SKI7 SHE d tel 01208 jene fixe ANAM OHI edlsor nts Kalle oye dise
129. g as 1 once a module is well into its monitoring This may sometimes be a higher value if an incoming value s checksum is unacceptable for some reason the count value will rise to show the number of samples since the last sample was acceptable Calculations take this into account At the bottom right of the screen are shown the equivalent ADC amps and watts values for the last acceptable data The blue label to the left displays the current day date and time as determined by the PC s own internal clock along with the number of minutes that have passed during the current day This is only for information Of interest to other programmers is the way in which the day name has been calculated The formula was found on the web via www terra es personal2 grimmer fol lowing advice from readers on the EPE Chat Zone via www epemag co uk Examine the Mains Monitor VB6 source code to see how it was implemented Between the bargraphs and display screen are shown the numerical val ues also associated with the screen display position The units shown may be changed between ADC amps and watts by clicking the allocated radio button at the top centre of the screen The selection is not stored to disk and will revert to ADC next time the program is run Storing data Each incoming waveform value is automatically stored to disk for fur ther analysis Data is stored consecu tively to a file whose name shows the curr
130. g techniques the reader should be able to confidently tackle servicing of most electronic projects Order code BP239 5 49 x r a lity TT pant 19 95 Over 1 000 projects Over 800 pages in Adobe Acrobat format 21 95 96 pages OSCILLOSCOPES FIFTH EDITION lan Hickman Oscilloscopes are essential tools for checking circuit operation and diagnosing faults and an enormous range of models are available This handy guide to oscilloscopes is essential reading for anyone who has to use a scope for their work or hobby electronics designers technicians anyone in industry involved in test and measurement electronics enthusiasts lan Hickman s review of all the latest types of scope currently available will prove especially useful for anyone planning to buy or even build an oscilloscope 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 Order code NE37 288 pages 24 00 Vintage 68 PRACTICAL ELECTRONIC FAULT FINDING AND TROUBLESHOOTING Robin Pain To be a real fault finder you must be able to get a feel for what is going on in the circuit you are exami
131. grammers e Includes a compiler for all the PICmicro devices O A hor cde AiE IpI I rid iar A F LLE 1n d dh 4 veda lle iG E unb ogf cba my x PEEM ANTR TE eiA E3271 04 lit me de met l TRI Se ee ee mn ax ee GE E EFIE rl d EL EHI Taso om d Dae ml ps DEEL SEEL g ts E in TU n a aia gp d ghi nn Lasar Ir c g og Minimum system requirements for these items Pentium PC running Windows 98 NT 2000 ME XP CD ROM drive 64MB RAM 10MB hard disk space Everyday Practical Electronics August 2008 T g 158 including VAT and postage supplied 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 FLOWCODE FOR PiCmicro V3 Flowcode is a very high level language programming system for PlCmicro microcontrollers based on flowcharts Flowcode allows you to design and simulate complex systems in a matter of minutes A Powerful language that uses macros to facilitate the control of devices like 7 segment displays motor controllers and l c d s The use of macros allows you to control these devices without getting bogged down in understanding the programming Flowcode produces MPASM code which is compatible with virtually all PlCmicro programmers When used in conjunction wit
132. h the Version 3 development board this provides a seamless solution that allows you to program chips in minutes e Requires no programming experience e Allows complex PlCmicro applications to be designed quickly e Uses international standard flow chart symbols e Full on screen simulation allows debugging and speeds up the development process e Facilitates learning via a full suite of demonstration tutorials e Produces ASM code for a range of 18 28 and 40 pin devices e New features in Version 3 include 16 bit arithmetic strings and string manipulation improved graphical user interface and printing support for 18 series devices pulse width modulation 12C new ADC component etc The Hobbyist Student version is limited to 4K of code 8K on 18F devices a i i as 2d os i ix i Lui i SPECIAL PACKAGE OFFER DIGITAL WORKS TINA Pro V7 Basic Flowcode V3 Hobbyist Student TINA Analogue Digital Symbolic RF MCU and Mixed Mode Circuit Simulation Testing and PCB Design 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 communication optoelectronic circuits test and debug microcontroller applications FPR ie DO ee ek DOSEREN Enter any circuit up to 100 nodes within minutes with TINA s easy to use schematic editor Enhance your sche
133. hievable in a home or school setting as well as a fully equiped lab Order code NE42 11 50 VIDEO PROJECTS FOR THE ELECTRONICS CONSTRUCTOR R A Penfold Written by highly respected author R A Penfold this book contains a collection of electronic projects specially designed for video enthusiasts All the projects can be simply constructed and most are suitable for the newcomer to project construction as they are assembled on stripboard There are faders wipers and effects units which will add sparkle and originality to your video recordings an audio mixer and noise reducer to enhance your soundtracks and a basic computer control interface Also there s a useful selection on basic video production techniques to get you started Circuits include video enhancer improved video enhancer video fader horizontal wiper improved video wiper negative video unit fade to grey unit black and white keyer vertical wiper audio mixer stereo headphone amplifier dynamic noise reducer automatic fader pushbutton fader computer control interface 12 volt mains power supply e ro arorele ad Om Iu E 5 45 288 pages 124 pages 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 CD ROM prices include VAT and or postage to anywhere in the world Send a PO cheque international money order sterling only m
134. hould be of the type normally used to connect serial modems to a PC ZU MEO E M Component layout on the PC Interface circuit board Everyday Practical Electronics August 2008 In the prototype four individual single pole miniature toggle switch es were used for S1 ato d A 4 way DIL switch may be used instead although less conveniently There are also panel mounting rotary BCD switches available which could be used although the author has not tried this and cannot recommend any particular type Both PC boards should be housed in suitable plastic cases The Mains Monitoring Board must be in a double insulated case ie no metal parts must pass through the case use plastic switches and nylon fixings for the PC board It is not possible to use and earthed metal case as this interferes with the radio transmission The mains input lead must be securley fixed with a suit able cable clamp Software Software for the PICs and PC is available for free download via the EPE website access via www epemag wimborne co uk Preprogrammed PICs are available from Magenta Electronics See their ad vert in the current issue for contact details The PC software was written in Visual Basic 6 VB6 but is sup plied as both a standalone EXE file and the source code To run the EXE you do not need VB6 to be installed If running the PC source code via VB6 you also need to have installed Joe Farr s Serial Interfac
135. ic C Builder or any other 32 bit Windows application development tool that supports calls to a DLL K8055 Kit VM110 Assembled USB Interface Board With a total of 33 input outputs including ana logue digital and TPWM output Connection to the computer is galvanically op tically isolated so that dam age to the computer is not possible thus providing a high level of secure implementa tion Supplied with test software amp examples K8061 Kit 48 95 High Power LED Driver Power up to four 1W or two 3W high power LEDs not incl Delivers accurate constant current required by most high power LEDs built in rectifier for easy connection to AC source compact size m short circuit protected no heatsink re xim quired P K8071 Kit 4 95 VM143 1W for 1W LEDs 7 55 VM143 3W for 3W LEDs 7 95 Remote Control by Telephone Turn up to three devices on or off over the telephone It is also possible to check the condition of a switch open or closed A major advantage of this circuit lies in the fact that audio signals are used to tell whether a specific output has been turned on or off Operation is protected by a user defined code which is simply keyed in from the telephone keypad K6501 Kit 29 95 219 95 26 95 18 95 29 95 USB DMX Interface Control DMX fixtures using a PC and USB interface test software and DMX Light Player soft ware is included a DLL is pro vided to writ
136. id Battery Zapper Video Reading Aid Digi Flash Slave AUGUST 07 TwinTen Stereo Amplifier Printer Port Hardware Simulator HFID Security Module V2 PC Scope Control Board Analogue Board SEPTEVBER 07 Flexitimer Main Board Display Board 1 Display Board 2 Display Board 3 set Pocket Tens Unit OCTOCBR 07 Simple Seismograph V8 Doorbell Main Board Display Board Standby Power Saver Transmitter Receiver PSU NOVEMBER 07 Vehicle Voltage Monitor USB Electrocardiograph Inductance amp Q Factor Meter Experimenter s Audio System Main Board PSU x Teach In 08 Master Control Board DECEMBER 07 iPod or MP3 Player Charger AVR ISP Socketboard PIC Speech Synthesiser Playback Record JANUARY 08 Serial I O Controller MIDI Drum Kit Main Board Display 70 PRO ECTTITLE Phone Fax Missed Call Alert PIC Carillon FEBRUARY 08 MIDI Drum Kit Optical Sensor Studio Series Stereo Preamplifier Pre Amp PSU Electrosmog Sniffer MARCH 08 Fluorescent Tube Driver Studio Series Stereo Headphone Amplifier APRIL 08 Studio Series Remote Control Module MIDI Activity Detector PIC In Circuit Programming Add On PC Controlled Burglar Alarm Main Board Display Board MAY 08 PC Controlled Burglar Alarm Keypad Electric Mobility Buggy Monitor Mini Theremin JUNE O8 Monopoly Money U
137. ies or provide data on articles that are more than five years old Please also ensure that all components are still available before commencing construction of a project from a back issue Note Some supplements etc can be downloaded free from the Library on the EPE Online website at www epemag com No advertisements are included in Volumes 1 and 2 Everyday Practical Electronics August 2008 STORE YOUR BACK ISSUES ON CD ROMS A great way to buy EPE Back Issues our CD ROMs contain back issues from our EPE Online website plus bonus articles all the relevant PIC software links and web links Note no free gifts are included Order on line from www epemag wimborne co uk shopdoor htm or www epemag com USA prices or by phone fax email or post BACK ISSUES CD ROM ORDER FORM Please send me the following Back Issue CD ROMs Volume N mbers mT Price 14 45 each includes postage to anywhere in the world Post Code LITT UT LJ enclose cheque P O bank draft to the value of LI please charge my Visa Mastercard Maestro CENO Tee c Ue Card Secu rity Code The last 3 digits on or just under the signature strip valid From cce ee EA DAE eere Maestro Issue No SEND TO Everyday Practical Electronics Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Tel 01202 873872 Fax 01202 874562 E mail orders epemag wimborne co
138. igh base current beyond I B will not work in the way it did for the common emitter circuit in Fig 2 If we make R ten times smaller at 47 2 we get a collector current of 112mA and a base current of 112 100 1 12mA The voltage drop across R is 0 053V 47 x 1 12mA so the emitter voltage is 5 0 052 0 7 4 247V assuming Vg is 0 7V This gives the current through the load of 4 247 38 112mA A tenfold change in base resistor has had relatively little effect on base current 1296 and the transistor 1s still in the forward active region Now we can see what happens when the load resistance varies Remember that the common emitter circuit with the saturated transistor Fig 2 delivered more or less the same voltage across the load as we doubled and halved its value For the emitter follower we will use R 470 and f 100 as above For R 19Q load halved we have approximately V 3 4V I 182mA I 1 82mA The voltage drop across R is 470 2 x 1 82mA 0 86V giving the load voltage of 5 0 86 0 7 3 4V For R 76 2 load doubled we have approximately V 4 05V I 53mA Lager D uouusoseniwases A I 0 53mA The voltage drop across R is 470 2 x 0 53mA 0 25V giving the load voltage of 5 0 25 0 7 4 05 V Unlike the common emitter circuit doubling and halving the load resistance has caused a significant change in load voltage This voltage change is due to
139. ight be capable of switching on an LED but that s about all The way around this problem is to use a relay with heavy duty contacts to switch the power However your electronic switching circuit may not even have sufficient power to drive a relay coil at least not directly This DC Relay Switch board is the an swerto that type of situation It utilises a heavy duty automotive type relay with Mainateatulnes Automotive style high current relay Operates from 12V DC power supply Suitable for low voltage switching only up to 50V DC Activated by low current Isolated input to provide flexible switching options Can be activated using a low voltage AC signal or an oscillating signal Relay on LED indication Normally open NO and normally closed NC relay output terminals 22 30A contacts runs from a 12V supply and requires just 400LA of signal to trig ger the relay That s made possible by using an optocoupler and some simple electronic circuitry to drive the relay What s more the input trigger signal does not have to be ground referenced This means that you can drivethe relay board from just about any DC signal whether it normally sits at around 12V 5V or OV It can even be driven by low voltage AC or by a signal that is rapidly switching on and off Current drive In practice the DC Relay Switch requires a current to drive it rather than a voltage A signal current of just 400uA or more sw
140. ign also incorporates an optional includes PCB with overlay also explained This over temperature heat sensor that will disconnect the LEDs all electronic i E 5 book will give you the speakers if the output stage gets too hot components and clear it knowledge and skill Configurable for supply voltages English instructions 1 F al DM that will elevate you between 22VDC 70VDC uU e Requires 12VDC power ABNES ID into a fully fledged Supplied with a silk E ul E constructor Softcover screened PCB relay and all electronic components y full colour 128 pages Recommended box UB5 205 x 275mm HB 6015 0 83 each a m a a a How To Order Great Nits for EIeCEEOnIG Enthusiasts Universal Stereo Preamplifier Kit Minivox Voice Operated Relay KC 5159 5 25 post and packing KC 5172 4 95 post and packing Based around the low noise LM833 dual op amp IC this Voice operated relays are used for hands free radio preamp is designed for use with a magnetic cartridge communications and some PA applications etc This tiny kit cassette deck or dynamic microphone It features RIAA IEC fits into the tightest spaces and has almost no turn on equalisation and is supplied with all components to build delay 12VDC 35mA required Kit i IS either the phono tape or microphone version supplied with PCB electret mic e Measuring only 80 x 78 x 30mm it is ideal for and
141. iltered using a 100nF capacitor and fed via a 1kQ resistor to the inverting input pin 2 of op amp IC1a which is connected as a comparator The voltage on IC1a s non invert ing input pin 3 is set by set point trimpot VR1 via a 1OkQ resistor When the thermistor voltage at pin 2 is above the voltage set by VR1 at pin 3 IC1a s output is low Conversely when the thermistor voltage is below the voltage on pin 3 IC1a s output is high around 68V Hysteresis has been added to prevent the output of IC1a from os cillating when the inverting input is close to the switching threshold This hysteresis is provided by trimpot VR2 and diode D3 in series between IC1a pins 1 and 3 Trimpot VR2 enables the amount of hysteresis actually positive feedback to be adjusted With low hysteresis the temperature only has to drop by a small amount for IC1a s output to switch low again after it has switched high If VR2 is set for high hysteresis the temperature must fall by a much larger amount before IC1a s output switches low again Diode D3 sets the direction of the hysteresis action As shown it pro vides hysteresis when pin 1 of IC1a goes high Alternatively if mounted in the opposite direction it provides hysteresis when IC1a s output goes low Where the circuit is intended to provide a switched output when the temperature goes above a certain val ue the diode is installed as shown on the circuit and parts overlay Fig 2
142. into the palm of your hand vet still Includes m da Oo Ta e the powertul features found in larger oscilloscopes imd T www picotech com scope479 to check out our full line of PC based instruments or call O 1480 396 395 for information anda product catalogue Up close and personal e C apu uc JT Tecnnolalk Mark Nelson PANs and NFC do you need to know about these new expressions Will they change your personal life Mark Nelson thinks so and is determined to tell you all about them in any case HERE S far too much alphabet soup on the menu these days and you too may be fed up with an excess of meaningless new acronyms Of course some of them do catch on eventually such as PIN and LED Others fail to click such as SMS short messaging system the original name for texting That s enough philosophy so let s crack on with the subject or rather subjects in hand Without NFC you cannot have PANs but perversely I ll deal with PANSs first PANs Twenty years ago PANs were touted as the replacement for POTS with POTS being the Plain Old Telephone Service The PANs acronym in those days stood for the Positively Amazing Network services that British Telecom and other telcos were introducing along with the new digital exchanges such as System X and System Y Many of these new network based services failed to catch on but a few did such as ring back calling you back when
143. ional and home editions The book was written with the non expert busy person in mind it explains what hardware requirements you need in order to run Windows XP successfully and gives an overview of the Windows XP environment The book explains How to manipulate Windows and how to use the Control Panel to add or change your printer and control your display How to control information using WordPad notepad and paint and how to use the Clipboard facility to transfer information between Windows applications How to be in control of your filing system using Windows Explorer and My Computer How to control printers fonts characters multimedia and images and how to add hardware and software to your system How to configure your system to communicate with the outside world and use Outlook Express for all your email requirements how to use the Windows Media Player 8 to play your CDs burn CDs with your favourite tracks use the Radio Tuner transfer your videos to your PC and how to use the Sound Recorder and Movie Maker How to use the System Tools to restore your system to a previously working state using Microsoft s Website to update your Windows set up how to clean up defragment and scan your hard disk and how to backup and restore your data How to successfully transfer text from those old but cherished MS DOS programs Order code BP514 7 99 INTRODUCING ROBOTICS WITH LEGO MINDSTORMS Robert Penfold Shows the reader how to b
144. is used The Settings parameter is an important one and it is used to set the baud rate the type of parity checking the number of data bits and the number of stop bits By default this will be 9600 baud no parity eight data bits and one stop bit 9600 n 8 1 This word format is usually the best one to use when interfacing user add ons to a PC but a higher baud rate might be preferable in some applications 19200 is the highest standard baud rate and it gives double the default transfer rate which works out at about two kilobytes per second To increase the baud rate to 19200 it 1s just a matter of deleting 9600 and replacing it with 19200 Turbo speeds Windows and modern PCs support some turbo baud rates and one of these can be used if an even higher rate of transfer is required Some PCs can apparently use a maximum rate of 230400 baud or even higher but the highest rate that is likely to work with most PCs is 115200 baud With this baud rate a maximum transfer rate of about 11 kilobytes per second is obtained Note that the figure used for the baud rate parameter must correspond to one of the standard rates supported by Windows Simply using any baud rate that takes your fancy will produce an error message SComm1 MSComm1 MSComm Alphabetic Categorized MSComm1 1 True False J comMone 1024 Properties g D comInputModeText 960 False 512 CommPort Returnsjsets the com
145. isplay colours and positions to the time stamped data 4 Constructional Checksum Incoming values both time and current data contain a checksum The PC checks that the checksum value corresponds with its own as sessment of the byte data received and only if the two values corre spond does the PC accept that the data is valid Position the TX and RX modules so that data is adequately and con sistently received This may entail changing their angles in relation to each other to ensure maximum reception Check that the TX module cor rectly sends receivable data When it is known that time and waveform data is being received note the posi tion on the waveform screen where the waveform is being plotted It will develop as a straight line at this time because the monitoring module is not monitoring mains current being used The output of the op amp to the PIC s ADC is biassed to be about a half way value resulting in an ADC conversion value above zero Consequently at this time the dis played waveform will be higher on the screen than it should be When the incoming values are known to be consistently arriving click on the Set Zero button at the top left of the screen This sets the present data value into a memory register From then on this memo rised value is deducted from any further incoming waveform values so that they are now always related to the zero position on screen The offset value is
146. itches low thus pulling pin 5 of IC1b low again and preventing any further clock pulses from reaching IC2 Video inputs four channels four S video sockets and four RCA phono composite video sockets Audio inputs four left and right channels via RCA phono sockets Outputs one video channel S video and RCA phono connectors plus left and right audio channels RCA phono connectors Switching via relays with selection via front panel pushbutton switches and LED indicators Power Supply 12V DC plugpack rated at 150mA or more Everyday Practical Electronics August 2008 1 Constructional D antsalisit 1 PC board code 676 available from the EPE PCB Service size 198 x 157mm 1 low profile ABS instrument case size 225 x 165 x 40mm 5 double RCA phono sockets PC mount 5 mini 4 pin DIN sockets 90 PC mount 5 panel mounting RCA phono sockets yellow 1 2 5mm concentric DC power socket PC mount 4 SPST pushbutton switches 8 mini DIL 12V DPDT relays 10 6G x 6mm long self tapping screws 8 PC board terminal pins 1mm diameter 1 12V 150mA DC plugpack Semiconductors 1 4093B quad Schmitt NAND IC1 1 4017B decade counter IC2 1 78L05 5V regulator REG1 4 2N7000 MOSFETs Q1 Q4 4 3mm red LED LED1 LED4 1 3mm green LED LED5 5 1N4004 400V 1A diodes D1 D5 Capacitors 1 2200uF 25V RB electrolytic 1 1OuF 16V RB electrolytic 2 100nF multilayer monolithic 1 100nF MKT polyester 1
147. itches the relay on and when there is no current the relay switches off In practice this means that you can drive the relay switch board using an external circuit that normally drives an LED When the LED is on the relay is on and vice versa Alternatively the relay board can be connected so that the relay is off when the external LED is lit Ifthe LED is multiplexed ie switch ed on and off at a fast rate then the relay board can be configured to switch on the relay whenever the LED is being driven by the switching circuit An LED on the DC Relay Switch board Everyday Practical Electronics August 2008 1k E INPUT L CAN BE INCREASED IN VALUE D3 C LK1 IN FOR MULTIPLEXED LED CONNECTION AT INPUT DG RELAY SWITGH G 2 Ql 7 BC549 E Constructional Project RLY1 30A CONTACTS d E 3 RELAY 4A LED1 e K D3 1NA4148 A K D1 D2 1NA4004 A K Fig 1 the circuit is triggered by applying a signal to optocoupler OPTO1 When the phototransistor in OPTO1 turns on it turns on transistor Q1 and this then turns on transistor Q2 which drives the relay and LED1 provides on offindication for the relay ie it lights when the relay switches on and goes off when the relay is off As shown in the photographs the DC Relay Switch comprises a small PC board that includes the relay the optoisolator two transistors and various other minor components It is powered from a 12V DC sup
148. its far right If neither player has a playable tile the knock flag is not cleared and the flag value increments After four knocks the software knows that the game cannot be taken further It then calculates how many tiles each player has successfully played and shows the results on line 1 with the quantities prefixed by U and P respectively followed by the indication of who has won If the tile counts are equal the game is a draw and the winner is shown as X The counters tile use monitoring is incremented in BCD so that there is no need to use a binary to decimal routine before the respective value can be displayed meaningfully Once the winner has been declared switch S1 can be pressed to start another game The program loops and effectively shuffles the tiles while reallocating a further seven to each player You then play the next game in the same way as the first The player who won the previous game now becomes the one to find the starting double If a draw exists the choice of starter is made randomly When several games are played consecutively no record is kept of who has won the most Such matters are left to you and a pen and paper Note how during the game the played tiles display is truncated to only show a maximum number of tiles ignoring the earlier ones if there are too many to show on a single line LCD cursor control Throughout the game the LCD cursor is turned on
149. k with diode D5 providing reverse polarity protection The resulting 12V DC rail is filtered using a 2200UF capacitor and powers the relays and the indicator LEDs The 12V DC rail also feeds volt age regulator REG1 which provides a 5V rail to power IC1 and IC2 This line also powers LED5 via a 3900 current limiting resistor to provide power indication Construction A single sided PC board measuring 198 x 157mm EPE code 676 accom modates most of the circuitry This fits snugly inside a standard low profile plastic instrument box measuring 225 x 165 x 40mm with all ofthe audio video and power connectors accessed from the rear panel The selector buttons and LEDs are mounted on the front panel The component layout and wir ing details are as shown in Fig 2 Begin construction by fitting the 11 wire links then fit the five dual RCA phono sockets CON6 to CON10 to the rear of the board Make sure that these socket assemblies are pushed all the way down onto the board and that their plastic locating spigots go through their matching holes before soldering the pins Follow these with the DC input con nector CON11 and the five mini DIN connectors CON1 to CON5 Once again make sure that these connectors are all properly seated before soldering them The next step is to fit eight PC board terminal pins which are later used to terminate LEDs 1 to 4 These pins go along the front of the board in the positions mark
150. l famous etector 131 2 x TL071 Op Amps P N diod Pipe Descaler High Power KIT 864 37 99 amp See the new SPI 5 c 1N4007 ded witin aa monNor Rit 069 2295 buil Mkiib and MKIllon the web 2008 Catalogue available 1 inc RESISTOR PACKS C Film P amp P or FREE with first order All Prices Include VAT Add 3 00 P amp P per order or 7 99 for next bs ora E N uU P amp P 1 75 per order NO VAT day Chqs P O amp most major cards accepted Mail Order Only RP7 10 each value total 730 0 25W 4 65 Kenn MEE CIKO 30 GT RP10 1000 popular values 0 25W 6 60 SHI Lele mE BEGCHRO INI CSF GENT www magenta2000 co uk RP4 5each value total 305 0 5W 4 20 10 NEWSTEAD STREET RP8 10 each value total 610 0 5W 6 85 7 sales magenta2000 co uk RP11 1000 popular values 0 5W 8 95 BANSI E PEN e TSENG OROIN Measure Test amp Control TE POOL SERVICING YOUR COMPLE ROTOTYPE NEED PC based Budget Irt l EUROCARD measure e Test Tw 160 x 100 mm 1 amp EE Equipment u 0 Tooling A TET SES Scopes 2 Photoplots jhe Dee Ana ogue Multimeters Ae Aw Digital IO A VAT Function Le data Generators 924 49 loggers from 99 from 49 p Price example Any size and contour possil Robot and PC Weather Optional Controller Stations T e Soldermask Kits EL Wind speed e Fast turnaround iS i d irecti zi e Silkscreen i g E E AAG e4 l
151. last 3 digits on or just under the signature strip with your name address etc Or order on our secure server via our UK website Overseas customers your credit card will be charged by the card provider in your local currency at the existing exchange rate Everyday Practical Electronics August 2008 READERS TECHNICAL ENQUIRIES Email techdept epemag wimborne co uk 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 we cannot accept legal responsibility for it A number of projects and circuits published in EPE employ voltages that can be lethal You should not build test modify or renovate any item of mains powered equipment unless you fully understand the safety aspects involved and you use an RCD adaptor COMPONENT SUPPLIES We do not supply electronic components or kits for building the projects featured these can be
152. le for rising temperature detec tion link LK1 is placed in its L H position ie to the left when the board is orientated as shown in Fig 2 and diode D3 is positioned so that its band cathode is closest to the bottom of the Everyday Practical Electronics August 2008 SENSOR At NTC THI 05 THERMISTOR 100nF TEMPERATURE SWITCH REG1 7808 Constructional 11 4V IC1 LM358 REVERSE D3 IF LINK LK1 1N4148 IS IN H L POSITION A nu 100uF m 16V LED1 62 K T RELAY 16V Ji 1 8k K D2 1N4004 A O NC O COM O NO O NC O COM O NO ior C IKI sc B C Ql CK BC337 E L H 10k DIODES ZENERS a K GND Fig 1 temperature is monitored using a thermistor TH1 while either op amp IC1a or IC1b drives transistor Q1 and the relay according to a rising or falling temperature see text Trimpot VR1 sets the temperature trigger point Thefull circuit diagram for the Tem perature Swich is shown in Fig 1 The temperature is monitored using an NTC negative tempera ture coefficient thermistor TH1 a device which exhibits a variable resistance with temperature At high temperatures the resistance of the thermistor is low while at lower tem peratures its resistance is higher A 1kQ resistor from the 8V supply feeds current through the thermistor which then produces a voltage which is inversely proportional to tempera ture This voltage is f
153. le by mail order plus more CD ROMs EPE PCB SERVICE PCBs for EPE projects ADVERTISERS INDEX Readers Services Editorial and Advertisement Departments 10 22 30 35 52 20 28 46 54 57 18 21 26 ad 60 63 64 67 70 72 Web www QUASAR electronics Get diosa In PIC amp ATMEL Pr grammers e have a wide range of low cost PIC Lr ATMEL Programmers Complete range and ocumentation available from our web site Programmer Accessories 0 pin Wide ZIF socket 7IF40W 14 95 8Vdc Powersupply PSU010 18 9 eads Parallel LDC136 3 95 Serial LDC441 3 95 USB LDC644 2 95 NEW USB amp Serial Port PIC Programmer USB Serial connection i E BE ZIF Socket and USB lead extra 18Vdc Kit Order Code 3149KT 39 95 Assembled Order Code AS3149 49 95 NEW USB All Flash PIC Programmer USB PIC programmer for all 2 Flash devices No external power supply making it truly portable Supplied with box and Windows XP Software ZIF Socket and USB lead not incl Assembled Order Code AS3128 44 95 Assembled with ZIF socket Order Code AS3128ZIF 59 95 PICALL ISP PIC Programmer a Will program virtually all 8 to 40 pin serial mode AND parallel mode PIC15C family PIC microcontrol m lers Free Windows soft ware Blank chip auto detect for super fast bulk programming Optional ZIF socket Assembled Order Code
154. le can be up to 35m long Includes plastic case 130x100x30mm Power 12Vdc 500mA Kit Order Code 3108KT 54 95 Assembled Order Code AS3108 64 95 Infrared RC 12 Channel Relay Board m Control 12 onboard relays with included infrared remote con trol unit Toggle or momentary 15m range 112 x 122mm Supply 12Vdc 0 5A Kit Order Code 3142KT 47 95 Assembled Order Code AS3142 59 95 Audio DTMF Decoder and Display Detect DTMF tones from tape recorders receivers two way radios etc using the built in mic or direct from the phone line Char acters are displayed on a 16 character display as they are received and up to 32 numbers can be displayed by scroll ing the display All data written to the LCD is also sent to a serial output for connection to a computer Supply 9 12V DC Order Code PSU445 Main PCB 55x95mm Kit Order Code 3153KT 24 95 Assembled Order Code AS3153 34 95 Telephone Call Logger Stores over 2 500 x 11 digit DTMF numbers with time and date Records all P buttons pressed during a call No need for any con nection to computer during operation but logged data can be downloaded into a PC via a serial port and saved to disk Includes a plastic case 130x100x30mm Supply 9 12V DC Order Code PSU445 Kit Order Code 3164KT 54 95 Assembled Order Code AS3164 69 95 ot Ne Products ere are a few of the most recent products dded to our range S
155. len Eigar Using the temperature switch it s easy to rig warning lights or alarms for excessive engine or gearbox oil temperatures In fact anything s that hot in the car with the exception of the exhaust gas and cylinder head can be monitored Photo Ford Temperature Switeh A cheap general purpose adjustable design that can work all the way up to 245 C HERE ARE MANY automotive performance applications where you want to turn something on or off based on a measured temperature Ra diator cooling fans over temperature warning lights or alarms intercooler or amplifier fans they all need a cheap and easily adjusted temperature switch Temperature switches are available commercially but this build it your self design has some major advantages over normal thermostats and tempera ture switches First it can be adjusted very finely you can literally set to Adjustable temperature switching from O C to 245 C Double pole changeover 5A relay contacts Selectable rising or falling temperature switching Adjustable hysteresis Easy to build 30 within a degree the temperature at which the switch triggers Second the hysteresis ie the differ ence between on and off temperatures is adjustable That lets you set the system up so that the device you re switching isn t constantly cycling at the trigger point You can set a wide hysteresis to switch something on and off at two widely spac
156. lf Electronic Project Kits Looking for a particular KIT Checkout Jaycar s extensive range We have kits and electronic projects for use in ias e Audio amp Video e Car amp Automotive Order Value Cost Order Value Cost 10 49 99 5 200 499 99 30 50 99 99 10 500 40 100 199 99 20 Max weight 12lb 5kg Heavier parcels POA Minimum order 10 Deluxe Solar Educational Kit KJ 6694 7 95 postage amp packing e Computer A series of do it yourself UE ecticationas ES ERAN e Lighting How to order power Includes solar cell e Power E Call Australian Eastern Standard Time Mon Fri module musical unit es Pod e Test amp Meters Phone 0800 032 7241 plastic lamp motor Fax 61 2 8832 3118 Email techstore jaycarelectronics co uk B Post P O Box 107 Rydalmere NSW 2116 Australia a ON Expect 10 14 days for air parcel delivery adaptors e General Electronics Projects just for fun accessories and plastic pto x www jaycarlectronic co A UOUU Uoc IZ Pu f nube T Monday Friday 09 00 to 17 30 GMT 10 hours only HH gy For those who want to write P 0 Box 107 EN Eum a Rydalmere NSW 2116 Sydney AUSTRALIA _ Electronics www OUS co uk PCB Production Development 0 1 Copper Stripboard i Tracks Holes O17 25k 241 37H 36T 50H 36T 170H 39T 38H 391 199 119x 455mm 46T 179H Stripboard t
157. ll remain the choice until the selected IDs are changed or the program terminated The default is always for All Units Cost per unit At the bottom right of the screen are two boxes into which you enter the cost per unit kilowatt hour of electricity used The current price may be found on your last electricity bill Enter the value into the upper box and the symbol you want to be shown for the currency involved eg or When the boxes have been given data click the Save Cost but ton to store the data to disk All val ues stored to disk can be examined through the MainsMonitorSettings txt file if you wish When the Start button is clicked the waveform values are related to the cost factor and running totals calculated When all the wanted waveforms are on screen the boxes at the left of the screen are updated with the costs represented by the display The screen is always cleared of previous data when the Start button is clicked If you move the mouse cursor across the display screen the ADC amps and watts values at the cursor position are displayed at the bottom left of the screen Constructional Mains Monitor Recalll Save C Display Curent Date Selected Date 12 05 2007 C Display From To 11 22 2007 12 02 2007 12 01 2007 C Display Since 3600 1 052 3264 2 1 23 3 0 61 SE 4 5 6 0 18 ZI 7 0 21 8 2280 g 10 1944 11 12 13 1632 14 15 1296 16 D 648 31
158. mA when there is 5V between its and inputs and 10mA when there is 12V between these terminals If this exceeds what the trigger circuit can deliver then the 1kQ resistor in series with pin 1 of the Everyday Practical Electronics August 2008 optocoupler can be increased Dou bling this resistor eg to 2 0kQ will halve the current requirement but if you make the resistor s value too high then the optotransistor may not turn on sufficiently to drive the relay circuit The minimum recommended trigger current is 400uA This corresponds to using a 22kQ resistor in series with OPTO1 for a 12V power supply and a 7 5kQ resistor for a 5V supply EPE CRICKLEWOOD ELEG TRONIGS Established 1981 Frustrated with your suppier Visit our component packed website for a vast range of parts old and new many unavailable elsewhere www cricklewoodelectronics com 1000 s OF PRICES REDUCED Alternatively phone us on 020 8452 0161 with your requirements lewood felectronics com Visit our shop at 02 O S45 O1 6l 40 42 Cricklewood Broadway London NW2 3ET 25 eoan NELORIIECT amare TO mar CTR D RON oe fum igen drum sounds Us ay SS computerlor PS nd Upto seven instruments atfone time recussion plate ha 1 ndipl j T sensor GEI CU K patchfand volume sj TEACH IN Using RIC micro PURO Dro Contr S ve amme 9 5 LA Hs Commands Pins mee f impleWeDICon
159. matics 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 first digital design It is so powerful that you will never outgrow its capability e Software TINA includes the following Virtual Instruments Oscilloscope Function Generator Multimeter Signal Analyser Bode Plotter Network Analyser Spectrum Analyser Logic Analyser Digital Signal Generator XY Hecorder Flowcode V3 Hobbyist Student For details on Flowcode see the previous page for simulating digital logic circuits e Create I your own macros highly scalable e Create This offer gives you two seperate CD ROMs in DVD style cases the software will
160. meric l c d display Fully protected expansion bus for project work USB programmable ASSEMBLY FOR PiCmicro V3 Formerly PiCtutor Assembly for PlCmicro microcontrollers V3 0 previously known as PlCtutor by John Becker contains a complete course in programming the PIC16F84 PlCmicro microcontroller from Arizona Microchip It starts with fundamental concepts and extends up to complex programs including watchdog timers interrupts and sleep modes The CD makes use of the latest simulation techniques which provide a superb tool for learning the Virtual PICmicro micro controller this is a simulation tool that allows users to write and execute MPASM assembler code for the PIC16F84 microcontroller on screen Using this you can actually see what happens inside the PlCmicro MCU as each instruction is executed which enhances understanding e Comprehensive instruction through 45 tutorial sections e Includes Vlab a Virtual PlCmicro microcontroller a fully functioning simulator e Tests exercises and projects covering a wide range of PlCmicro MCU applications e Includes MPLAB assembler e Visual representation of a PlCmicro showing architecture and functions e Expert system for code entry helps first time users e Shows data flow and fetch execute cycle and has challenges washing machine lift crossroads etc e Imports MPASM files 1h ASS ELLET PRICES Hobbyist Student wc ue ones 45 inc VAT Institutional Schools HE FE Ind
161. merous clear illustrations throughout 135 pages Order code NE40 22 50 THEORY AND 368 pages REFERENCE THE EMERGENCE OF BROADCASTING IN BRITAIN Brian Hennessy The beginning of any great enterprise should be recorded for posterity Few knew that the Children s Hour Uncles Arthur Jeff and Caractacus were also the engineers who struggled by day to develop technical equipment and would soon become Assistant Controller Station Director and Organiser of Programmes for the BBC This is a very human account from the dawn of radio to the attainment of a Royal Charter in the late 1920s It tells of the struggles and frustrations of engineers in developing innovative equipment and of the great John Reith who battled with everyone to bring the BBC from a staff of four up to a Corporation of several hundred Brian Hennessy s book also describes the devlopment of broadcasting equipment the search for premises and looming bankruptcy before ending with the emergence of a firmly established Chartered Corporation the BBC Meticulous research over many years over a hundred photographs plans and diagrams as well as interviews with many of those who were there at the time make this a valuable and original work for those involved in media studies for radio enthusiasts or simply for those interested in radio and the fascinating story of the emergence of broadcasting 436 pages Order code EBB 26 00 PRACTICAL E
162. mes The transistor contains two diode PN junctions this is true of both NPN and PNP transistors the junctions are simply the opposite way in the two types requiring opposite voltages for the same operation The two junctions can be either forward biased on or reverse biased off so there are actually four different regions of operation for the transistor These are shown in Table 1 When a transistor is used as a switch it is usually switched between the saturation and cutoff regions In the cutoff region both junctions in the transistor are reverse biased and no current flows through the transistor Everyday Practical Electronics August 2008 except some leakage In the saturation region both junctions are forward biased so each junction will have about 0 7V across it For example we might have V 0 75V and Vac 0 70V the collector to emitter saturation voltage V will be the difference between these in this case 0 05 V As we have already said the forward active region is used for amplifiers The base emitter junction will be forward biased with typically around 0 7V across it V which is slightly lower than the saturation case The collector to emitter voltage V will typically be a few volts so the base collector junction will be reverse biased by this value minus V The reverse active region is not commonly used but does have some applications in some types of logic and analogue switching circuits
163. mine by mail order from Studiospares tel 08456 441020 or sales 9 studiospares com London NW2 Godfrey Manning G4GLM Edgware Middx by email Thanks for the info Godfrey FTP Site Dear EPE On the www epemag wimborne co uk website the FTP pub area does not seem to match the Tree area On the Tree I can see the artwork PDF files but from the pub area the folder is not there I use an FTP manager to sync the files to my PC but I have to go in manually and download the artwork from the Tree Is this just me or can the data be moved Mike Von Der Heyden Kimberley South Africa via email Alan replies Good point Mike the reason for this 1s because the PCB Artwork PDFs aren t hosted on the FTP site they re hosted on the EPE web server for bandwidth and disk space reasons The direct web link in case this helps is www epemag wimborne co uk pcbs sorted by month issue year At the moment we don t have any solution to offer but I ll work on it Alan Winstanley via email Everyday Practical Electronics August 2008 Surfing The Internet t Work Alan Winstanley Putting on a MAC Many Internet users will know the sinking feeling when they start to download a large file and after an encouraging start their sprightly download rate proceeds to fall off a cliff the deliberate throttling back of data traffic by some service providers frustrates the efforts of avid Internet users engaged in fetching larg
164. mobile phone or it might be incorporated into something that everyone carries like a pen or comb The choice will certainly be contested with abattle royal fought between the banks mobile phone operators and third party organisations what about eBay for instance all of which have conflicting commercial interests There are security and standardisation issues to be addressed too as well as a way of build ing compatible transponders into point of sale terminals The one thing that s not in dispute is the technology behind near field communication which is fully capable of rising to the occasion Watch this space 20 ELECTRONICS MANUALS ON CD ROM 29 95 EACH ELECTRONICS SERVICE MANUAL A practical reference ma electronics servicing tect UHRHHEBHO B CIE Rect mr ae 2s DH i Everything you need to know to get started in repairing electronic equipment 9 Around 900 pages 9 Fundamental principles 9 Troubleshooting techniques 9 Servicing techniques Choosing and using test equipment 9 Reference data 9 Manufacturers web links 9 Easy to use Adobe Acrobat format 9 Clear and simple layout 9 Vital safety precautions 9 Professionally written Supplements SAFETY Safety Regulations Electrical Safety and First Aid UNDERPINNING KNOWLEDGE Electrical and Electronic Principles Active and Passive Components Circuit Diagrams Circuit Measurements Radio Computers Valves and manufacturers Data etc PRA
165. monitors camcorders satellite dishes and much more Order code MGH3 200 pages 228 pages 394 pages 21 99 VINTAGE RADIOS Tony Thompson Since the 1920s the radio set has been an important part of most people s lives In the thirties and forties the wireless was an important piece of furniture and a potent symbol of status beautifully made floor standing and table top sets in veneered wood and trendy Bakelite became the focal points of living rooms up and down the land After the war the emphasis began to change towards portability and the change from valves to transistors in the 1960s changed the radio into a more useful but far less interesting object The book tells the collector and the armchair wireless enthusiast everything he or she needs to know about classic radios from the 1920s to the end of the 1960s All the important makes and models are discussed and the author also covers buying and selling care and restoration and many other topics including foreign radios and radio related ephemera Illustrated with hundreds of colour photographs this is the perfect collector s companion to the fascinating topic 208 pages hardback Order code CVR 21 95 ALL PRICES INCLUDE UK POST amp PACKING Everyday Practical Electronics August 2008 PROJECT BUILDING ELECTRONIC PROJECT BUILDING FOR BEGINNERS R A Penfold This book is for complete beginners to electronic project building It provid
166. munications port Fig 1 A range of parameters for MSComm can be set via the Properties Inspector These include the word format and baud rate There are various handshaking options available but handshaking is unnecessary with most user add ons The speed of the peripheral device and the PC are both likely to be very high compared to the maximum transfer rate of a serial port even if the port is used at a turbo rate Serial port handshaking can be problematic so it is best avoided unless it is really needed for some reason When handshaking is not required make sure that the None option is selected If any other setting is used there could be problems with data flow grinding to a halt due to the PC expecting handshake signals that it will never receive Hit the buffers InBuffer and OutBuffer are two more parameters that will usually be important Programs can read each byte of data as it is received but it is not essential for things to be handled in this fashion The byte by byte approach may sometimes be the best way of doing things but bytes are often transmitted in groups of a fixed size It is then more efficient if the received data is stored in a section of memory called a buffer and processed when the appropriate number of bytes have been received Similarly a program does not have to wait for one byte to be transmitted before it sends the next one to the serial port Instead a block of data can be stored in a
167. n it is on all the time This can make choosing the series resistor for each LED difficult You don t really want to be doing a trial and error experiment on 1024 LEDs See this month s Circuit Surgery Software The software that accompanies this article can be found in the Download Area of the EPE website under Pic n Mix The code consists of the low level SPI access routines based largely on a previous article and the control code that performs the actual display multiplexing through the port expander ICs The control code is just 140 instructions long demonstrating how simple the application is The low level SPI functions are implemented in two functions TX SPI and TXRX SPI TXRX SPI is a standard SPI driver routine which can provide both the transmit and receive functionality TX_SPI is a transmit only version which has been implemented to help make the code for updating the display as fast as possible The two functions MCP23S17WriteByte and MCP23S17ReadByte build on top of TXRX SPI to provide the actual port expander device specific functionality With these two routines you can configure and use the MCP23S17 device at an abstracted level ie you need only think about device register numbers and data to write read in them You can forget about how the chips are wired and the intricacies of the SPI bus TXRX SPI handles all that for you The control application software assumes that yo
168. na With near field communication you can swamp your own locality more simply using very low frequencies which are easier to generate The field strength is low posing less of a health risk and avoiding the need to consider licensing regulations Using the human body as an electrical transmission medium is a complex subject and difficult to summarise in a few sentences In essence however communicating between two devices using the body as a medium involves the use of a PAN transmitter and a PAN receiver The body worn device is obviously battery operated and couples a small displacement current capacitively through the human body to the receiver The transmitter itself need not be in direct contact with the skin so long as the transmitter electrode is close to the body allowing the skin to act as a capacitor By modulating the electric current we can transfer data to the receiver with the earth acting as the return path Sounds scary Perhaps but it s stated that the current used in PANSs is one billionth Everyday Practical Electronics August 2008 of an amp a nanoamp less than the nerve currents that flow naturally through your body A number of modulation and multiplexing systems are proposed and although prototype devices work at not more than 2 4kbit s significantly higher data rates are expected to be feasible Body talk Who will be the early adopters of body PANs It s hard to tell while most devices a
169. nd functions K8057 Kit Remote Control Transmitter Compact 2 button IR keychain remote compati ble with most Velleman IR receivers 2 powerful IR LEDs for a range of up to 15m 16 channels 12 55 allow use of multiple transmitters in one room easy channel configuration no jumpers required 6 25 MK162 Mini Kit Remote Control Receiver Two channels with relay output K 24VAC DC 1A max ultra compact fa channel and reception indication through LEDs toggle pulse selec tion for each channel learn mode for channel ID all settings are stored in EEPROM compatible with most Velleman Kit IR remotes MK161 Mini Kit 3 30V 3A Power Supply Suitable as a power supply for all common Velleman kits using a sta bilised DC voltage between 3 and 30V 3A max Of course this pow er supply unit can also be used for other purposes By replacing the trimmer by a potentiometer it may even be used as an adjustable power supply unit Supplied with heat sink 19 95 K7203 Kit Sound to Light Unit Low mid and high channels Sensitivity adjustment per channel LED indication per channel Attractive translu cent enclosure Microphone hd ed Noise suppressed according to EN55015 K8017 Kit 27 55 Clap On Off Switch Operate your lighting simply by clapping your hands Good immunity against sur rounding noises l clap or 2 clap mode selection 2 clap mode features built in safety turn off timer
170. nications for the Alba Group and Chairman of the Consumer Electronics Council of industry body Intellect says We recognise that things could go wrong You never know for sure until you go live We have an assessment system in place to monitor help line queries We learned lessons with Freeview and with digital radios for cars which unexpectedly would not work with the aerials that come fitted to many cars It s a learning experience but we have got the assessment issue covered Installation cost estimates are based on a 45cm dish with single LNB fitted at second floor level with 15m of cable Freesat believes 85 of installations will fall in this category James Atkins assures that if customers buy a receiver and then find installation is much more expensive they will be able to take their box back and get a refund Confusion On the day following launch we visited a flagship Dixons Currys Digital store in London s Oxford Street A Freesat Humax HD box was on display amongst 11 DTTV Freeview boxes piles of boxed DTTV Freeview products and signs explaining DTTV Freeview reception There was no sign to explain that the Freesat receiver needed a different aerial from the Freeview receivers and when we asked an assistant whether the HD receiver would work with an existing TV aerial he pointed to a Freeview sign and told us to check the Freeview coverage area Everyday Practical Electronics August 2008 FireFly Radio
171. ning In this book Robin Pain explains the basic techniques needed to be a fault finder Simple circuit examples are used to illustrate principles and concepts fundamental to the process of fault finding This is not a book of theory it is a book of practical tips hints and rules of thumb all of which will equip the reader to tackle any job You may be an engineer or technician in search of information and guidance a college student a hobbyist building a project from a magazine or simply a keen self taught amateur who is interested in electronic fault finding but finds books on the subject too mathematical or specialised The fundamental principles of analogue and digital fault finding are described although of course there is no such thing as a digital fault all faults are by nature analogue This book is written entirely for a fault finder using only the basic fault finding equipment a digital multimeter and an oscilloscope The treatment is non mathematical apart from Ohm s law and all jargon is strictly avoided Order code NE22 ELECTRONIC TEST EQUIPMENT HANDBOOK Steve Money In most applications of electronics test instruments are essential for checking the performance of a system or for diagnosing faults in operation and so it is important for engineers technicians students and hobbyists to understand how the basic test instruments work and how they can be used The principles of operation of the various types of test
172. niversal High Energy LED Lighting System JUY 08 PIC MIDI Sound Wave Generator Galactic Voice Coolmaster J Four Channel A V Selector DC Relay Switch For High Current Loads Versatile Temperature Switch Mains Monitor Monitor Interface EPE SOFTWARE All software programs for EPE Projects marked with a Star and others previously published can be downloaded free from our Downloads site accessible via our home page at www epemag co uk PCB MASTERS PCB masters for boards published from the March 06 issue onwards can also be downloaded from our UK website www epemag co uk go to the Downloads section EPE PRINTED CIRCUIT BOARD SERVICE Order Code Project Quantity Price enclose payment of cheque PO in sterling only to Everyday Practical Electronics Gard No Aa kee aaa bie ican Aaa eiaa Valid From Expiry Date Card Security No Maestro Issue No Signature Note You can also order PCBs by phone Fax or Email or via the shop on our website on a secure server http www epemag co uk Everyday Practical Electronics August 2008 CEASSIFIEDFADVERTISEMENTS er eee eee Everyday Practical Electronics reaches more UK readers than any other UK monthly hobby electronics magazine our sales figures prove it We have been the leading monthly magazine in this market for the last twenty three years If you want your advertisements to be seen by the largest readership at the mos
173. ntaining the whole Teach In 2006 series originally published in EPE in PDF form interactive quizzes to test your knowledge TINA circuitsimulation 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 The Teach In series covers everything from Electric Current through to Microprocessors and Microcontrollers and each part includes demonstration circuits to build on breadboards or to simulate on your PC In addition to the Teach In series the book includes 15 CMOS based simple projects from the Back To Basics series by Bart Trepak these are Fridge Freezer Alarm Water Level Detector Burglar Alarm Scarecrow Digital Lock Doorchime Electronic Dice Kitchen Timer Room Thermometer Daily Reminder Whistle Switch Parking Radar Telephone Switch Noughts and Crosses Enigma and a Weather Vane There is also a MW LW Radio project in the Teach In series 152 pages CD ROM Order code ETI 8 50 CIRCUITS AND DESIGN A BEGINNER S GUIDE TO TTL DIGITAL ICs R A Penfold This book first covers the basics of simple logic circuits in general and then progresses to specific TTL logic integrated circuits The devices covered include gates oscillators timers flip flops dividers and decoder circuits Some practical circuits are used to illu
174. o includes the power supply for driving the master control section 36 Everyday Practical Electronics August 2008 20V DC supplies down to 15V in conjuction with smoothing ca pacitors C5 C6 C10 and C11 These supplies provide power for the Hall effect current transducer X3 The 20V DC supply is fed to regulator IC3 which produces an output of 5V DC as required by the PIC transmitter and optional LCD display module PIC controller The circuit for the controlling PIC unit is shown in Fig 3 The PIC16F876A is labelled as IC1 It runs at 3 2768MHz as set by crystal X1 in conjunction with capacitors C2 and C3 The PIC s RAO port pin 2 converts the incoming voltage signal from the power monitoring circuit to an equiv alent decimal value Once a minute the value is added to a counter and another counter is incremented to keep track of the number of samples taken since monitoring began from switch on or reset via switch S2 At the same time the totals are transmitted to the PC via buffer transistor TR1 and the 433MHz radio TO D4 C14 AMPS NC NC NC NC NC a D1 1N4148 k Constructional transmitter TX module IC2 The TX module can be used without a transmitting licence as it conforms to the legal requirements in terms of frequency and transmitting power It is available as a ready made unit from a variety of sources The one in the model came from RS Com ponents and was manufactured by
175. of information about how computers work It picks up where Bebop left off guiding you through the fascinating world of computer design and you ll have a few chuckles if not belly laughs along the way In addition to over 200 megabytes of mega cool multimedia the CD ROM contains a virtual microcomputer simulating the motherboard and standard computer peripherals in an extremely realistic manner In addition to a wealth of technical information myriad nuggets of trivia and hundreds of carefully drawn illustrations the CD ROM contains a set of lab experiments for the virtual microcomputer that let you recreate the experiences of early computer pioneers if you re the slightest bit interested in the inner workings of computers then don t dare to miss this Order code BEB2 CD ROM GETTING THE MOST FROM YOUR MULTIMETER R A Penfold This book is primarily aimed at beginners and those of limited experience of electronics Chapter 1 covers the basics of analogue and digital multimeters discussing the relative merits and the limitations of the two types In Chapter 2 various methods of component checking are described including tests for transistors thyristors resistors capacitors and diodes Circuit testing is covered in Chapter 3 with subjects such as voltage current and continuity checks being discussed In the main little or no previous knowledge or experience is assumed Using these simple component and circuit testin
176. omm event which are numbered from one to seven and these are the events that trigger them No Event 1 Send 2 Receive 3 Change in the CTS line 4 Change in the DSR line 5 Change in the CD line 6 Ring detect 1 End of file When a byte of data is received and the program breaks out of the loop the byte is placed into string variable SerData The stored ASCII character is used as the caption for the label component but it is first converted into its ASCII code value This is the opposite of the process used when transmitting data MSComm does actually have a binary mode which would seem to be a better choice for interfacing to do it yourself add ons but using it in practice seems to be problematic Results Fig 3 shows the program running with the link in place across pins 2 and 3 of the serial port The slider has been set for a high value which has been transmitted received read from the port and displayed correctly on the label In Fig 4 the link wire on the port has been removed the slider has been set for a low value but no data has been received The reading on the label has therefore remained unchanged Form1 Va 246 Fig 4 A low value has been set using the slider but the display has not Everyday Practical Electronics August 2008 changed because the link between the port s TXD and RXD terminals has been removed New values are transmitted but not received 29 By Join Glite amp Ju
177. ou try to debug the program having found that it doesn t do what you expected Take each routine stage by stage Get one small section of code working before you move onto the next Then get that next small section working before you try to join it to the previous part Be methodical is the key command when programming As you get further into PIC programming you may decide that you would like to write code in conjunction with a simulation program These help you to debug code on your PC before downloading it to the PIC Such programs will not replace the thought processes needed when writing code but they will let you find many but not all of the errors more quickly However the author finds it very easy to check program operation when the code is in the PIC and the PIC is connected to its various interfaces Had the PIC16F628 not been an EEPROM device then this would not be an acceptable technique but it is rapidly reprogrammable and so is usable as a live test bed One further point when writing a program the author finds it useful to supplement its software file name with a suffix number increasing the number at each save of a major addition or change to the previous code written This allows an earlier version to be recalled should the need arise for example PICITOI ASM PICITO2 ASM PICITO3 ASM etc PICs versus hardware Athough microcontrollers can be enormously beneficial there is the likelihood that it m
178. ouse St Albans Road Stafford ST16 3DR Telephone 0845 166 2314 local rate N R BARDWELL Ltd est 1948 Electronic Component Supplies LED s Semis IC s Resistors Caps etc send 44p for lists 1000 s bargains at our secure site www bardwells co uk www lec org uk BOWOOD ELECTRONICS LTD See our website for the full range and compatible video overlay units WWW PIC OSD COM 288 Abbeydale Rd Sheffield S7 1FL 0845 166 2329 local rate Suppliers of Electronic Components Place a secure order on our website or call our sales line All major credit cards accepted Web www bowood electronics co uk Unit 1 McGregor s Way Turnoaks Business Park Chesterfield S40 2WB Sales 01246 200222 Send 60p stamp for catalogue Contact Stewart on 01202 873872 Stewart kearn winborne co uk Sea e a r UK amp International Suppliers of Electronic Components amp Kits Capacitors Resistors Transistors Optoelectronics PCBs Breadboard Solder Switches Cable Batteries Tools CMOS ICs Potentiometers P amp P 2 50 orders over 25 free P amp P No Min Order No VAT NEW 2008 MAIL ORDER CATALOGUE AVAILABLE AT www rshelectronics co uk VALVES AND ALLIED COMPONENTS IN STOCK Phone for free list Valves books and magazines wanted Geoff Davies Radio tel 01788 574774 EPEGIRONICSBIEACRZIN Everyday Practical Electronics August 2008 BYSMIKETOOEEY plus FREE CD ROM 71 Europe s Largest Surplus
179. out 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 UC or 2 x 10Wrms j amp short cir eed for rectifi only AC supply 14 25 Audio A 100Wrms 4ohm DC sup ply circuit on board with LED indication ideal for ac tive speaker system or sub woofer guitar amp home theatre systems etc Over load amp short circuit protected K8060 Kit 13 25 VM700 Assembled with heatsink 28 75 Audio Amplifier Stereo 2 x 50Wrms or a Mono 100Wrms ampli fier Three input sensitivity settings Overload amp short cir cuit protection protection against incorrect power supply polarity Speaker transient suppression K4004 Kit PC based using supplied windows software All standard oscilloscope functions are available Its operation is just like a normal oscilloscope Connection is through the computer s parallel port the scope is completely optically isolated from the computer port K8031 Kit PC Function Generator 0 01Hz to 1MHz crystal based op tically isolated from the PC Sine square amp triangle Includes Win dows 95 98
180. p point for the temperature switch where the temperature is shown in the lefthand column C and the voltage required V to be on the middle pin moving contact of the set point pot VR1 is shown on the righthand side For example if you want the switch to trip at 145 C the pot will need to be turned until the measured voltage is 1 425V Everyday Practical Electronics August 2008 33 Constructional Project m The temperature switch can be used to operate electric radiator fans and you epeoneae can adjust the difference between the switch on and switch off temperatures With high loads like these fans you should run an extra heavy duty automotive relay Photo Bosch can use the relay s normally open NO and COM pole contacts Fig 3 shows these connections The relay s contacts are rated to 5A for currents higher than this use the on board relay to switch another heavy duty automotive type relay Note that because a double pole double throw DPDT relay has been used another completely independent circuit can also be switched simulta neously This other circuit can even turn off the second device as the first is switched on Set up There are two ways of setting the action of the Temperature Switch First if you have another means of monitoring the temperature eg via an engine coolant temperature gauge or a temporary temperature probe and display wait until the measured temperature rea
181. perature Light Position and motion Force pressure and flow Part 2 Interfacing Number systems Computer architecture Assembly language Interfacing A to D and D to A conversions Data communications Programmable logic controllers Data acquisition project Part 3 Signal processing Transfer function Active filters Instrumentation amplifier Noise Digital signal processing 295 pages Order code NE38 31 00 67 THEORY AND REFERENCE THE AMATEUR SCIENTIST CD ROM The complete collection of The Amateur Scientist articles from Scientific American magazine Over 1 000 classic science projects from a renowned source of winning projects All projects are rated for cost difficulty and possible hazards Plus over 1 000 pages of helpful science techniques that never appeared in Scientific American Exciting science projects in Astronomy Earth Science Biology Physics Chemistry Weather and much more The most complete resource ever assembled for hobbyists and professionals looking for novel solutions to research problems Includes extensive Science Software Library with even more science tools Suitable for Mac Windows Linux or UNIX 32MB RAM minimum Netscape 4 0 or higher or Internet Explorer 4 0 or higher Order code AS1 CD ROM BEBOP BYTES BACK and the Beboputer Computer Simulator CD ROM Clive Max Maxfield and Alvin Brown This follow on to Bebop to the Boolean Boogie is a multimedia extravaganza
182. ply via an on board screw terminal block A second 2 way screw terminal block is used for the trigger signal inputs External connections to the relay con tacts can be made using either PC mount spade connectors or a 3 way screw ter minal block The spade connectors are best for high current applications Finally the PC board can be fitted inside a small plastic UB5 case if this is required How it works OK let s see how the circuit works examine Fig 1 As shown the input trigger signal is applied to the LED inside optocoupler OPTO1 via a 1kQ resistor This resis tor limits the LED current to less than 12mA for a 12V signal and to less than 5mA for a 5V signal Diode D3 prevents the LED inside OPTO1 from breaking down and dissi patingtoo much power ifa reverse volt age is applied In this case D3 conducts and limits the voltage across the LED to a safe value ie to about 0 6V When current flows in the opto coupler LED the optotransistor conducts and supplies base current to transistor O1 via the 22kQ resistor from the 12V supply rail This switch es Q1 on which in turn switches Q2 on via its associated 1kQ base resistor When Q2 switches on relay RLY1 also switches on as does LED1 The 10kQ resistor between Q1 s base and ground OV ensures that Q1 switches off when the phototransistor in OPTO1 turns off Similarly the 1kQ resistor between Q2 s base and emitter ensures that this transistor switche
183. poles switching the video for each channel and the other two the audio The only reason we re not actually using a 4 pole 4 position mechanical switch is that they re no longer readily available Instead we re using eight mini DPDT relays four to switch the video signals and four to switch the audio These relays are driven by sepa rate driver circuits in turn controlled by a one of four selector circuit The circuit diagram for the Four Channel A V Selector is shown in Fig 1 The signal switching circuitry is at upper left and uses one relay to switch the two audio channels for each A V source and a second relay to switch Constructional Project the video signal ie Y and C for S video or the single composite video signal In this case relays 1 and 5 switch the signals for Source 1 while relays 4 and 8 switch the signals for Source 4 The remaining four relays for Sources 2 and 3 are identically con figured but have been omitted from the circuit diagram for clarity The coils for each pair of relays are connected in parallel and driven to gether by 2N7000 MOSFETs Q1 to Q4 However only Q1 and Q4 are shown on the schematic again for clarity The rest of the circuit performs the one of four selection It s based on just two low cost CMOS ICs a 4093B quad Schmitt NAND gate IC1 and a 4017B decade counter IC2 IC1a is connected as a free run ning relaxation oscillator operating at about 20kHz
184. press of the switches is required for each move holding down the switch to progressively move the cursor has been inhibited There is a brief pause between releasing a switch and when it can be pressed again to prevent switch bounce Note in the switch selection routine how a holding loop is used if no switch is pressed In another program this might allow the software to go off and do something else while a switch press is awaited When a highlighted tile has the correct face either side to match the right hand face of the last tile shown on line 2 press 3 to select it It is automatically turned to face the correct way on line 2 if the order is wrong Following selection via S3 the tile is renumbered to xx so that you cannot use it again as said the software ignores any xx tile face and does not allow its selection The PIC then tries to find a face value which matches the right hand side of the tile just selected Everyday Practical Electronics August 2008 If at any time you do not have a tile which can be played press S4 to knock in the traditional domino fashion This sets a flag which is cleared when a tile can be played by either you or the PIC When a knock is made the other player then tries to find a suitable tile If it is the PIC that cannot find a tile then it makes an equivalent knock and the display on line 2 remains the same apart from displaying the current knock value at
185. r the first 60 seconds show the PIC s time value incrementing and display the unit s identity Fig 7 The display then changes to show the increment ing time and average ADC value on Everyday Practical Electronics August 2008 Line 1 total accumulated current value and the number of samples on Line 2 Fig 8 The PC interface module must be connected to the COM port input and powered Do not connect anything to the current transducer at this stage To run the PC software in Record mode click the Start button on the main screen At the top left of the screen should be seen the timing counter value transmitted by the PIC changing every second The position where it is shown depends on the ID value also transmitted Different display colours are used depending on the ID value of the transmitting module Black is that used for module ID1 The wave forms plotted on screen are also of the same colour There are 15 vertical bargraphs towards the left ofthe screen These display the equivalent amplitude level of any unit s last received waveform value After every 60 seconds of PIC time the waveform data is also transmitted and plotted on screen The entire display width on the PC screen represents 24 hours of data which is plotted on screen in rela tion to the present time as known to the PC The lower lefthand part of the screen shows the real time at which waveform data for a module is received allocating different d
186. rack cutter Solderless Breadboard Tie Points i Powe Pai 3 32 640 175x42mm0 308 Many other sizes available us also jump wires amp matrix board PCB Production Drafting Materials A4 Artwork Film per 10 sheets Clear Manual Film 1 20 Clear Laser Film _ 1 75 White HQ Laser Film 4 62 Etch Resist Pens Dalo Pen Zoo Staedtler Fine Pen 1 20 Tes Etch Resist Transfers m Seno mixed DIL pads 2 24 a Seno mixed Rnd pads 2 24 wagssssti Alfac mixed pads 1 84 Jm Transfer Spatular 1 25 umi We carry the full ine of Seno amp Alfac PCB transfers see our web site for full details Soldering Irons x We carry in stock a wide range of Selle en and soldering accessories Irons from 12 to 100 Watts 25W 240V Ceramic 6 00 30W 240V Basic 4 68 Soldering Station A 48W adjustable temperature soldering station with a rotary di al LED Temperature metering on off switch iron holder and tip clean ing sponge This station features ac curate heat ning for instant compensation amp stable tempera tures o EE temperature range of 150 420 C Low volt age iron with Silicone cable Supply 240V Iron 24V 48W Model 167 540 49 00 Soldering Station A 48W adjustable temperature soldering station with a rotary di al Digital Temperature Indication on off switch iron holder and tip cleaning sponge This station fea tures accurate heat sensing for instant compens
187. re still experimental and expensive Medical applications for patients in hospital are a possibility whereas performance monitoring systems for professional and semi pro athletes already use this kind of technology This fitness market could expand a great deal if a mass market enabled prices to fall Jack Shandle of Wireless Net Designline argues that recreational runners and weekend cyclists might well wish to see at a glance how they had run or pedalled and how many calories they had burned Body PANs may not catch on but contactless near field communication is already a reality If you live or work in London and have a lobster card you re using it every time you touch in and touch out on public transport Some users are already using their cards to buy food cigarettes and newspapers too Near field communication could play a major enabling role in eliminating cash handling and speeding up payment using some kind of contactless communication device The commercial potential and convenience to you and me is crystal clear What s less obvious is which particular device or object will do the business and how There s no earthly reason why the debit payment device needs to have the same form factor as a credit card It could be your travel pass or a new kind of combined credit debit card that doesn t have to leave your pocket On the other hand the mechanism might involve an enhanced SIM card in your
188. re touching the chimes or gongs when the circuit is at rest they would then pull back bounce and strike small motors with hammers attached may also be used with suitable series resistors if required On standby the circuit draws a mere 20uA of power This can be reduced by increasing the value of R4 the author suc cessfully tried 10M or by replacing R4 and TR2 with a CMOS inverter However AA batteries should be able to provide 204A continuously for several years Thomas Scarborough Cape Town South Africa 10V to 12V LED Voltmeter Bargraph metering TE CIRCUIT shown in Fig 2 was built to monitor the voltage of a car battery during its charge discharge cycle The LED bars light up in roughly in 1V volt increments Below 10V Zener diode D16 does not con duct sufficiently to forward bias the base of transistor TR1 so no collector current flows As the input voltage increases above 10V TRI starts to conduct passing collector current through the LED array and resistor R2 The current flowing through R2 reduces the voltage across the Zener diode keeping its cathode at a constant 10V The value of R2 therefore determines the amps per volt passing through the LED array ie the meter sensitivity a value of 100 gives a LED array current of 10mA per volt above 10V input voltage electronic design ltd _ Atlas ESR Model ESR60 As the current through the LED array in creases from zero the
189. recaution to prevent punch through of the transistor Power for the circuit can be derived from any suitable 12V DC supply eg a plugpack or batteries Diode D1 pro vides reverse polarity protection while a 220uF capacitor decouples the supply OperaitingastheEinculjtetnomg2 4 VD C Want to operate the DC Relay Switch from 24V DC Here s how to do it e Use a 24V relay instead of a 12V relay eg 24V 30A relay e ncrease the voltage rating of all capacitors to 35V e Change the 2 2kQ resistor in series with LED1 to 4 7kQ 0 25W Everyday Practical Electronics August 2008 29 Constructional Construction The DC Relay Switch is built on a PC board EPE code 677 measuring just 46 x 61mm This board is available from the EPE PCB Service see page 70 The board fits inside a small 83x54x31mm approx plastic box and is secured us ing four M3 x 12mm countersink Nylon screws and nuts A 3mm Nylon washer is used between the PC board and the case at each mounting point to lift the board clear of the base Fig 2 shows the component layout on the PC board Begin construction by checking the PC board for any defects such as broken copper tracks and shorts between adjacent tracks WARNING DO NOT use this DC Relay Switch to switch 230V AC mains voltages The relay is not de signed to do this and itis danger ous to connect mains to the bare PC board If you do need to switch mains voltages then use this bo
190. rogram simply add another three zeroes at the beginning of each 5 bit line and terminate the value with another apostrophe e g b 00010001 Examine the ASM file and you will see all seven domino faces represented in the table at label CHRTABLE The binary values are preceded by RETLW to allow the table to be called and for a return to the calling point to be made with the specified value held in W The table starts at program address ORG h 400 When calling the table you must first set a suitable PCLATH value as it is not in the normal first 256 program locations The table is then accessed via a loop which allows the table values to be returned in W The program s routine for sending symbol data to the CG RAM is shown in Listing 10 2 Since seven domino symbols are required the loop is set to read and send 56 values to the CG RAM Note that the CG RAM is volatile and so its programmed data 1s lost when power is switched off and hence the CG RAM programming routine has to be repeated each time the PIC and LCD are turned on again Once the CG RAM has been programmed the symbols can be displayed by writing to the required display address between 0 and 15 in the normal way However the numerical values written through LCDOUT must be no greater than the user programmed CG RAM symbol addresses unexpected symbols will probably appear if you use a greater value Consequently when displaying the symbol the
191. ront panel holes and their leads soldered to the PC stakes It s a good idea to bend each LED s leads to its approximate shape before trying to fit the LED in position You do this by first bending the leads outwards by 70 about 8mm from the back of the LED body then bending them downwards by 90 about 6mm out from the first bends see photo Be sure to install them the right way around the longer anode lead goes to the left PC stake in each case see Fig 2 The soldered connections should be sufficient to hold the LEDs in place However you may also want to apply a small dab of epoxy cement to the rear of each LED to make them a little more secure Your Four Channel A V Selec tor is now complete and ready for testing Testing There are no setting up adjust ments to be made so the test proce dure is easy All you need to do is apply power to CON11 using a 12V DC plugpack or battery and check that the unit functions correctly First check that the green power LED immediately lights when power is applied If it does press one of the pushbuttons The red LED above that button should immediately light and you should hear a faint click as the two relays for that channel are activated Everyday Practical Electronics August 2008 AU 4 NEL RCE SELECTOR I L UDO OUT PONER 4 CHANI AV SOU Now press one of the other buttons Its LED should now light instead and there should
192. rowser Price 19 95 inc VAT Please send me CD ROM ORDER FORM Electronic Projects Electronic Circuits amp Components V2 0 ORDERING ALL PRICES INCLUDE UK O Analogue Electronics Version required POSTAGE L1 Digital Electronics V2 0 L1 Hobbyist Student O Analogue Filters O Institutional Student Single User Standard Version price Electronics CAD Pack O Institutional Professional 10 user includes postage to most countries in the world EU residents outside the Uk add 5 for airmail postage per order O Robotics amp Mechatronics O Site licence O Assembly for PlCmicro V3 O C for 16 Series PlCmicro V4 O Flowcode V3 for PlCmicro O Digital Works 3 0 PlCmicro Development Board V3 hardware i g i i i 1 i J g i i O TINA Pro V7 Basic Flowcode V3 Hobbyist Student I E E pli s Photos Note The software on each version is the a L1 roject esign Single User same only the licence for use varies i Project Design Multiple User under 500 students T Project Design Multiple User over 500 students I I l i i i I i J J gl Bani e a a e E OIL POSS A n ee POS COD spresti dx indes TORNO based esdue ede csi OIODIa UT oso ede dp eet ndi DIE HER ac Edu Ebr ied l O enclose cheque PO in sterling payable to WIMBORNE PUBLISHING
193. rst MSCOMM is not installed as a standard component so the first step is to go to the Project menu and select Components In the new window that appears tick the checkbox for Microsoft Comm Control 6 0 You do not have a suitable version of Visual BASIC if this control is not listed If it is present operate the Apply and OK buttons and the MSCOMM component will then appear with the other components in the toolbox This makes it possible to add MSCOMM to a form in the usual way Its telephone icon will appear on the form so that it can be selected but it will not be visible on the form of the compiled program The Properties Inspector gives access to a number of parameters when the MSCOMM component is selected Fig 1 This is similar to the properties window for the SerialPort see Fig 3 in the previous Interface June 08 and as in that case most of the default settings will usually suffice However some will probably require adjustment and the CompPort setting will almost certainly have to be changed if an add on USB serial port is used The ComPort is the serial port that will be accessed by the component and it is COMI by default An add on USB serial port is more likely to be COM3 or COMA and where appropriate this setting must be changed to the correct port number Note that it is possible to use two or more serial ports 28 but a different MSCOMM component will be required for each serial port that
194. rts with very simple PC to PIC experiments We use PC assembler to flash the LEDs on the programmer module and write text to the LCD Then we learn to use Visual C on the PC Flash the LEDs write text to the LCD gradually creating more complex routines until a full digital storage oscilloscope is created PH28 BU PIC amp Visual C Course comprising Enhanced 16F and 18F PIC programmer module Book Experimenting with PIC Microcontrollers Book Experimenting with PIC C Book Experimenting with Serial Communication PIC assembler PC assembler and PIC C compiler software on CD PIC16F627A PIC16F88 PIC16F870 and PIC18F2321 test PICs USB adaptor and USB lead 189 00 Postage amp ins UK 10 Europe 20 Rest of world 34 Professional Beginners These courses are the same as above except that we have rewritten Experimenting with PIC Microcontrollers so the instruction relates to the Microchip assembler This makes the course slightly more difficult but is ideal for beginners with a professional interest Order codes P928 MU and PH28 MU See our website for details Ordering Information Our PIC courses are supplied with a USB adaptor and USB lead as standard option U but can be supplied with an RS232 COM lead if required option S All software referred to in this advertisement will operate within Windows XP NT 2000 Vista etc For Windows 98 ME or DOS order P928 BS 159 pp Telephone with Visa Mastercard
195. s In cludes a 16F627 Flash Microcontroller that can be reprogrammed up to 1000 times for experimenting at will Software to compile and program your source code is included Kit Order Code VK8048KT 22 95 Assembled Order Code VVM111 39 95 Controllers amp are data acquisition and control units we have See website for full details 12Vdc PSU for all units Order Code PSUA45 8 95 Here are just a few of the gun and USB Experiment Interface Board 5 digital input chan nels and 8 digital out put channels plus two analogue inputs and A two analogue outputs i with 8 bit resolution Kit Order Code VK8055KT 20 95 Assembled Order Code VVM110 39 95 Rolling Code 4 Channel UHF Remote State of the Art High security 4 channels Momentary or latching relay output Range up to 40m Up to 15 Tx s can be learnt by one Rx kit in cludes one Tx but more avail d able separately 4 indicator LED s Rx PCB 77x85mm 12Vdc 6mA standby Two amp Ten Channel versions also available Kit Order Code 3180KT 44 95 Assembled Order Code AS3180 54 95 Computer Temperature Data Logger Serial port 4 channel tem perature logger C or F _ Continuously logs up to 4 separate sensors located 200m from board Wide range ot tree software applications for stor ing using data PCB just 45x45mm Powered by PC Includes one DS1820 sensor Kit Order Code 3145KT 17 95 Assembled Order Code AS3145 2
196. s 2 3 1 2 Digit Handheld AVO 8 Mk5 with Leads etc Goodwill GVT427 Dual Ch AC Millivoltmeter 10mV in 12 Metrix GX5000 Pulse Gen 50MHZ Programmable 150 ranges 10HZ 1MHZ Unused HP 3325A Synthesised Function Gen 21 MHZ Everyday Practical Electronics August 2008 Racal 1991 Counter Timer 160MHZ 9 Digit HP 531314 Universal Counter 3GHZ Opt 001 oven HP 53131A Universal Counter 225MHZ Oven In original AVO 8 Mk6 In Ever Ready Case with Leads etc Kids eb CH vU ces HP 8563A 6 000 MISCELLANEOUS MARCONI 2955A Radio Communications Test Set 1 000 MARCONI 2955 Radio Communications Test Set MARCONI 6960B RF Power Meter with head MARCONI 893C AF Power Meter Sinad Measurement HP 4192A Impedance Analyser with 16047A Text Fixture etc HP 8902A Measuring Receiver 150KHZ 1300MHZ 4 500 HP 85032A Calibration Kits SEAWARD Nova Pat Tester BIRD 43 Wattmeter Many Elements Available HUNTRON 1000 Tracker RACAL DANA 9343M LCR Databridge Digital Auto Measurements of RCL QD RACAL 9008 Automatic Modulation Meter 1 5MHZ 2GHZ MEGGER PAT2 Tester POWER SUPPLIES FREQU ATE FARNELL AP60 50 0 60V 0 50A 1KW Switch Mode 400 FARNELL H60 25 0 60V 0 25A THURLBY PL320QMD 0 30V 0 2A Twice Digita H P 6626A Precision High Resolution 4 Outputs 0 7V 0 15MA or 0 50V 0 0 5A Twice 0 16V 0 0 2A or 0 50V 0 2A Twice FARNELL XA35 2T 0 35V 0 2A Twice Digital 995 750 FARNELL B30 1030V 10A Variable No Meters F
197. s and cellular phones plus wireless local area networks As well as interference there are security issues too Among the non radio alternatives there are infrared optics OK not very practical for communication devices kept in pockets and wallets and electrical field sensing methods using the body as a wet string antenna described below PANs needn t be confined to the home or office The applications extend to your car shopping malls railway stations and airports An in car PAN could detect the presence of the user thereby allowing the mobile handset to automatically acquire pertinent information for driving such as weather and road conditions Other applications include mobile commerce in which a user of a mobile device communicates with another machine for transactions such as ticket purchase vending and other small purchases We are now entering the realm of near field communication NFC mentioned earlier so we should examine the differences between near and far field communication Far and near In any kind of conventional wirefree communication our aim is to project the signal over a considerable distance hence the term far field In near field communication it s different Big distances are not the target so there s no need to seek the ultimate in efficiency You maximise far field transmission efficiency by matching the impedance of the transmitter to free space using a carefully designed anten
198. s off when Q1 switches off The 1uF capacitor on Q1 s base is necessary if the input is driven using an AC signal or some other switching signal This capacitor is connected into circuit using link LK1 and filters the resulting signal on pin 4 of OPTO1 to produce a steady DC voltage This ensures that Q1 remains on whenever the input signal is applied Note that LK1 is only necessary for AC input signals It can be left out of 1 PC board code 677 available from the EPE PCB Service size 46 x 61mm 1 plastic UB5 box size 83 x 54 x 31mm 1 SPDT 12V 30A PC mount horn relay or equivalent RLY1 2 2 way screw terminal connectors 5 08mm pin spacing 1 3 way screw terminal connectors 5 08mm pin spacing 3 PC mount 6 4mm spade connectors 1 2 way pin header 2 54mm pin spacing LK1 1 jumper shunt for LK1 4 M3 x 12mm countersunk nylon screws and nuts 4 M3 nylon washers Semiconductors 1 4N28 optocoupler OPTO1 1 BC549 NPN transistor Q1 1 BC327 PNP transistor Q2 2 1N4004 1A diodes D1 D2 1 1N4148 diode D3 1 3mm red LED LED1 Capacitors 1 220uF 16V PC radial elect 1 1uF 16V PC radial elect Resistors 0 25W 1 1 22kO 1 10kQ 1 2 2kO 3 1kQ the circuit ie the 1uF capacitor is disconnected for DC trigger signals DiodeD2 provides spike protection for transistor Q2 when the relay is switched off It shunts the back EMF voltage spike generated when the relay switches off a necessary p
199. satisfaction of a complete working design makes it all worthwhile If you can t take occasional bouts of desperation isolation from friends and family followed by periods of ecstasy and feelings of well being towards all humanity leave programming alone The author though has become a programming addict and thrives on the challenges come what may But always remember that Murphy s Law has its most powerful influence when programming is involved If the microcontroller or other computer can misunderstand what you mean by your commands it will It is up to you to see the way in which each and every one of your commands will actually be interpreted You are the intelligent one the computer simply obeys your instructions Next month in the concluding part of Teach In 2008 we present a short discussion on sophisticated randomising and a practical example of it in use Please reserve deliver a copy of Everyday Practical Electronics for me each month Title Address Postcode First Name Surname Tel Everyday Practical Electronics is published on the second Thursday of each month and distributed S O R by SEYMOUR Make sure of your copy each month cut out or photocopy this form fill itin and hand it to your newsagent Electronics Engineers Join A Winning Team UK Europe and Middle East The Lektronix Group of Companies are the worlds leading provider of Industrial Automation repairs with an
200. sh memory In 66000 bytes you can store over 500 images which would make for quite a long animation assuming you have the skills and patience to create them This author is looking at the feasibility of using software to convert short sequences of video into 32 x 32 pixel monochrome picture stills We will report back on the progress of this and how well the panel works when construction is complete The software has been developed in MPLAB and is targeted towards the PICISF family of parts and the PICI8F2520 in particular It should not be difficult to move to a different processor although it will require care if moving from the PIC18F family www stewart of reading co uk Check out our website 1 000s of items in stoc PM3082 195 DIGITISING STORAGE OSCILLOSCOPES HP 54616B Digitising 500MHZ 2GS S 2 TEKTRONIX TDS520 Digitising 500MHZ 500MS S 2 Channel TEKTRONIX TDS360 Digitising 200MHZ 1GS S 2 Channel TEKTRONIX 2232 Dual Trace 100MHZ 100MS S HP 54600B Dual Trace 100MHZ 20MS S with RS232 2HP Probes Ops Manual Pouch amp Front Cover TEKTRONIX TDS224 Digitising 100MHZ 4 Channel MARCONI 2024 1 250 to 1 500 HP 3312A Function Gen 0 1HZ 13MHZ AM FM SCOPEMETERS SPECTRUM ANALYSERS Sweep Tri Burst etc FLUKE 97 Dual Trace 50MHZ 25 MS S TEKTRONIX 2465B 4 Channel 400MHZ Delay Cursors etc incl Tek Probes PHILIPS PM3082 2 2 Channels 100MHZ Delay TB etc HP 8112A Pulse Gen 50MHZ HP 8116 Pulse Function
201. st amp packing This terrific little car is fun to build and will introduce young minds to the concepts of mechanical construction and solar electric propulsion It can run purely from solar power or from the included hand cranked generator Great fun for years 84 e Forward and reverse control Approx 200mm long are monitored by a microcontroller so the functionality is extensive Kit contains PCB and all specified electronic components Smart Card Reader and Programmer Kit B M KC 5361 15 95 post amp packing 3 Program both the microcontroller and EEPROM in the popular gold silver and emerald wafer cards Card used needs to conform to IS0 7816 standards which includes ones sold by Jaycar Powered by 9 12 VDC wall adaptor or a 9V battery Instructions outline software requirements that are freely available on the internet Kit supplied with PCB wafer card socket and all electronic components PCB measures 141 x 101mm Solar Eco House Kit KJ 8924 7 25 post amp packing The house is fun to build and will introduce your child to the eco friendly concepts in a deceptively entertaining way It has it own solar panel and a windmill to supply free power to L the lighting amp sound circuits or it die can run from ordinary batteries 4 Simple and safe for ages 8 e Requires 2 x AA batteries for no solar operation Requires 9 12VDC wall adaptor Maplin UGO1B 13 99 Build Yourse
202. strate the use of TTL devices in the real world Order code BP332 5 45 PRACTICAL ELECTRONICS CALCULATIONS AND FORMULAE F A Wilson C G LA C Eng F LE E FI E R E F B I M Bridges the gap between complicated technical theory and cut and tried methods which may bring success in design but leave the experimenter unfulfilled A strong practical bias tedious and higher mathematics have been avoided where possible and many tables have been included The book is divided into six basic sections Units and Constants Direct Current Circuits Passive Components Alternating Current Circuits Networks and Theorems Measurements Order code BP53 5 49 MICROCONTROLLER COOKBOOK Mike James The practical solutions to real problems shown in this cookbook provide the basis to make PIC and 8051 devices really work Capabilities of the variants are examined and ways to enhance these are shown A survey of common interface devices and a description of programming models lead on to a section on development techniques The cookbook offers an introduction that will allow any user novice or experienced to make the most of microcontrollers Order code NE 26 23 50 142 pages 256 pages 240 pages COMPUTING AND ROBOTICS WINDOWS XP EXPLAINED N Kantaris and P R M Oliver If you want to know what to do next when confronted with Microsofts Windows XP screen then this book is for you It applies to both the Profess
203. supplied by advertisers We advise readers to check that all parts are still available before commencing any project in a back dated issue ADVERTISEMENTS Although the proprietors and staff of EVERYDAY PRACTICAL ELECTRONICS take reasonable precautions to protect the interests of readers by ensuring as far as practicable that advertisements are bona fide the magazine and its publishers cannot give any undertakings in respect of statements or claims made by advertisers whether these advertisements are printed as part of the magazine or in inserts The Publishers regret that under no circumstances will the magazine accept liability for non receipt of goods ordered or for late delivery or for faults in manufacture TRANSMITTERS BUGS TELEPHONE EQUIPMENT We advise readers that certain items of radio transmitting and telephone equipment which may be advertised in our pages cannot be legally used in the UK Readers should check the law before buying any transmitting or telephone equipment as a fine confiscation of equipment and or imprisonment can result from illegal use or ownership The laws vary from country to country readers should check local laws A roundup of the Iatest Everyday News from the world of electronics Freesat now on air Barry Fox reports on the UK s new free satellite service Freesat HE UK s free satellite service Freesat has now gone on air Viewers who cannot get the DTTV Freeview servi
204. t economical price our classified page offers excellent value The rate for semi display space is 10 VAT per centimetre high with a minimum hieght 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 398a Ringwood Road Ferndown Dorset BH22 9AU Phone 01202 873872 Fax 01202 874562 Email epeads wimborne co uk For rates and information on display and classified advertising please contact our Advertisement Manager Stewart Kearn as above BTEC ELECTRONICS TECHNICIAN TRAINING NATIONAL ELECTRONICS VCE ADVANCED ICT HNC AND HND ELECTRONICS FOUNDATION DEGREES NVQ ENGINEERING AND IT DESIGN AND TECHNOLOGY LONDON ELECTRONICS COLLEGE 20 PENYWERN ROAD EARLS COURT LONDON SW5 9SU TEL 020 7373 8721 Receive 32 Channels Low power 5Hz GPS Modules d 5Hz update rate Built in antenna High sensitivity SAFFRON ELECTRONICS LTD Suppliers of High Quality Electronic Components since 1991 Resistors Caps Batteries Chargers Semiconductors LED s IC s PCB s Switches Solder Cable Wire Etc Online Catalogue and Shop available at www SaffronElectronics co uk 3 04 St Albans H
205. tch this space Setup issues aside Linux is an elegant OS that is literally child s play to use As a sign of things to come the Asus Eee PC http eeepc asus com global product htm is a very cheap from 200 small screen laptop with a choice of Linux or Windows Although initially designed for children its desirable features include a solid state disk from 2GB and very compact form factor that will appeal to mobile Internet workers It is a dinky thing and I was impressed by some quick keyboard trials EPE contributor Thomas Scarborough in Cape Town is pleased by the bundled office software but less so by the heat output For many general Internet users on the move the novel Asus Eee PC may be a breath of fresh air that offers the mass market a refreshing introduction to Linux In forthcoming articles I will describe the fly on the wall view of a real life Internet money laundering fraud and point to some DOS based tools to check your internet setup I will also look at online techniques to analyse domain name ownership networks and web site hosting will also be outlined Readers can email Alan at alan epemag demon co uk Everyday Practical Electronics August 2008 DIRECT BOOK SERVICE Electronics Teach In FREE CD ROM Mike Tooley A broad based introduction to electronics 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 co
206. tead of equations Cutting edge topics such as microcontrollers neural networks and fuzzy control are all here making this an ideal refresher course for those working in Industry Basic principles control algorithms and hardwired control systems are also fully covered so the resulting book is a comprehensive text and well suited to college courses or background reading for university students The text is supported by questions under the headings Keeping Up and Test Your Knowledge so that the reader can develop a sound understanding and the ability to apply the techniques they are learning Order code NE35 22 50 HOW ELECTRONIC THINGS WORK AND WHAT TO DO WHEN THEY DON T Robert Goodman You never again have to be flummoxed flustered or taken for a ride by a piece of electronics equipment With this fully illustrated simple to use guide you will get a grasp on the workings of the electronic world that surrounds you and even learn to make your own repairs You don t need any technical experience This book gives you Clear explanations of how things work written in everyday language Easy to follow illustrated instructions on using test equipment to diagnose problems Guidelines to help you decide for or against professional repair Tips on protecting your expensive equipment from lightning and other electrical damage lubrication and maintenance suggestions Covers colour TVs VCRs radios PCs CD players printers telephones
207. ted with the selection Key in the dates you require If you wish to store them for future use the next time the program is run then click the Save Dates button The initial dates are those last used by the author To select the display type click the appropriate radio button To start the display click the Start button Data values within any existing file called are plotted to screen in the area provided again with Everyday Practical Electronics August 2008 different colour lines representing the unit ID with which the data is associated files always have the respective unit ID recorded along with its data Data is displayed either as a continuous trace for each unit or as non continuous lines relating to any breaks in recording The screen width represents 24 hours of data and data from different dates always commences at the left The values associated with different dates can thus be compared You may also display the data for any given unit ID If you click the Se lect Units box at the top of the screen a drop down Combo box appears giving the various unit ID options Normally the first option is shown clicked so that data for all IDs is shown To select individual IDs click off the All Units X box Then click any chosen other unit ID box so that its X box is shown to be active Now when the Start button is clicked only data for the selected unit IDs will be displayed This se lection wi
208. the corresponding temperature For example if you want the relay to close at 120 C set VR1 so that its wiper voltage is 2 274V The accuracy will be within about 296 Remember if you wish the relay to close when the temperature goes above a particular value install link LK1 in position L H and install diode D3 as shown on the overlay diagram Fig 2 For the relay to close when the tem perature goes below a certain value Dant saisit 1 PC board code 678 available from the EPE PCB Service size 105mm x 60mm 1 NTC thermistor SOD27 leaded package 40 C to 300 C BC components 2322 633 83103 1 plastic case size 130 x 68 x 42mm approx optional 5 PC mount 2 way screw terminals with 5mm pin spacing 1 12V PC mount DPDT 5A relay RELAY1 1 3 way pinheader with 2 54mm spacing LK1 1 jumper shunt with 2 54mm spacing for LK1 1 3m length of single core shielded cable 1 50mm length of 4mm diameter heatshrink tubing 1 1kQ multiturn top adjust trimpot VR1 1 1MQ horizontal trimpot VR2 Semiconductors 1 LM358 dual op amp IC1 1 7808 8V voltage regulator REG1 1 BC337 NPN transistor Q1 1 5mm red LED LED1 1 16V 1W Zener diode ZD1 2 1N4004 1A diodes D1 D2 1 1N4148 signal diode D3 Capacitors 2 100uF 16V PC electrolytic 2 10uF 16V PC electrolytic 1 100nF MKT polyester Resistors 0 25W 1 1 22kQ 2 1kQ 4 10k 1 100 1 1 8kQ install link LK1 in position H L and install D
209. the engaged number you wanted becomes free BT callminder voicemail and the incredibly handy facility for finding out the number of the person who called you last 1471 and then ringing them back by pressing 3 Back to the future where PANs now stands for Personal Area Networks In this case personal does mean personal as we are talking about communication networks that revolve entirely and exclusively around you On this subject Wikipedia conveniently states A personal area network PAN is a computer network used for communication among computer devices including telephones and personal digital assistants close to one person The devices may or may not belong to the person in question The reach of a PAN is typically a few metres PANs can be used for communication among the personal devices themselves intrapersonal communication or for connecting to a higher level network and the Internet an uplink Personal area networks may be wired with computer buses such as USB and FireWire A wireless personal area network WPAN can also be made possible with network technologies such as IrDA Bluetooth UWB and ZigBee Wet string antennas If I were revising Wikipedia I would change this entry to use the word wirefree rather than wireless since to most people wireless means radio and nothing else For PANs radio is not necessarily the best solution considering the amount of radio smog arising from cordles
210. ther it is on or off Software is the receiver s magnetic field As long as a pre programmed provided on a 3 5 disk Kit includes PCB relays software tag is recognised by the receiver access is granted This Sh or t Ci rcul s B ook l l n cl udin g P dr S and all electronic components 8 12V DC power required module provides normally open and normally closed relay KJ 8502 11 95 post amp packing contacts for flexibility It works with all EM 4001 This full colour 96 page book has over 100 drawings and compliant RFID tags Kit supplied with aie diagrams The projects are fun to build and relevant to PCB tag and all electronic P M the electronics scene components Ww E in the new e As published in ET millennium Included with the book you get the baseboard plenty of spring terminals LIII II Ll B b and ALL the Automotive Headlight Reminder Kit PIC Based Logic Probe eee KC 5317 7 75 post amp packing KC 5457 4 50 post amp packing D ea e M Nothing is more frustrating than getting into your car to Unlike ordinary logic probes this one is driven by a PIC INCLUDING the bonus discover that you had left your headlights on and the car s processor and operates over a wide supply voltage of battery is flat This kit will warn you if the lights are still on 2 8VDC to 5VDC It is extremely compact and uses surface when the ignition has been switched off i Features optional door AT switch dete
211. troy sim SER CT C d y a M h kr i r NAG N A RAE PICIS REECH A NO speechito 0 j adlee y urlP n Avetis s D wicrocont ON VOL 1 BACK ISSUES January 1999 to June 1999 Plus some bonus material from Nov and Dec 1998 VOL 2 BACK ISSUES July 1999 to December 1999 VOL 3 BACK ISSUES January 2000 to June 2000 VOL 4 BACK ISSUES July 2000 to December 2000 VOL 5 BACK ISSUES January 2001 to June 2001 VOL 6 BACK ISSUES July 2001 to December 2001 VOL 7 BACK ISSUES January 2002 to June 2002 VOL 8 BACK ISSUES July 2002 to December 2002 VOL 9 BACK ISSUES January 2008 to June 2003 VOL 10 BACK ISSUES July 2003 to December 2003 VOL 11 BACK ISSUES January 2004 to June 2004 VOL 12 BACK ISSUES July 2004 to December 2004 VOL 13 BACK ISSUES January 2005 to June 2005 VOL 14 BACK ISSUES July 2005 to December 2005 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 VOL 18 BACK ISSUES July 2007 to December 2007 NOTE These CD ROMs are suitable for use on any PC with a CD ROM drive They require Adobe Acrobat Reader available free from the Internet www adobe com acrobat WHAT IS INCLUDED All volumes include the EPE Online editorial content of every listed issue plus all the available PIC Project Codes for the PIC projects published in those issues Please note that we are unable to answer technical quer
212. ts BASIC PRINCIPLES Electronic Components and their Characteristics Circuits Using Passive Components Power Supplies The Amateur Electronics Workshop The Uses of Semiconductors Digital Electronics Operational Amplifiers Introduction to Physics including practical experiments Semiconductors and Digital Instruments CIRCUITS TO BUILD The Base Manual describes 12 projects including a Theremin and a Simple TENS Unit ESSENTIAL DATA Extensive tables on diodes transistors thyristors and triacs digital and linear i c s EXTENSIVE GLOSSARY Should you come across a technical word phrase or abbreviation you re not familiar with simply look up the glossary and you ll find a comprehensive definition in plain English The Manual also covers Safety and provides web links to component and equipment Manufacturers and Suppliers Full contents list available online at www epemag wimborne co uk SUPPLEMENTS Additional CD ROMs each containing approximately 500 pages of additional information on specific areas of electronics are available for 19 95 each Information on the availability and content of each Supplement CD ROM will be sent to you PRESENTATION CD ROM suitable for any modern PC Requires Adobe Acrobat Reader which is included on the CD ROM Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Tel 01202 873872 Fax 01202 874562 PLEASE send me ORDER FORM O THE MODERN ELECTRO
213. u have stored a bit map image that you want to display on the LED panel in the 128 bytes of BANKI RAM inside the PIC18F2520 Four consecutive bytes 32 bits in total represent the status of the LEDs on a single row with the most significant bit in the first byte being the top left LED and the least significant bit in the last byte being the bottom right LED The operation of the main loop in the program performs the following actions 1 Turn off the LEDs in the current row 2 Select the next row of the display 3 Read the data for the current row out of the image buffer memory and place on the display 4 Wait for 1ms 5 Goto 1 When the software reaches the last row on the panel it simply loops back to the top This approach works fine for static images If you want to display animations you will need to decide when you do the processing to perform the update to the image buffer The simplest solution is to change the entire image during the I ms delay after showing the last bottom row An alternative however is to update each row in the image buffer one at a time during the 1ms delay for that row Which method you use will depend on where you are fetching your new data from and how quickly you can get it Each image is only 128 bytes in size When you consider that this entire program is only 588 bytes out of a possible 66584 flash memory locations you have plenty of scope for storing a complex animation in fla
214. ual RCA phono connectors on 4 Band Code 1 red red orange brown brown black orange brown brown black red brown orange white brown brown brown black brown brown Everyday Practical Electronics August 2008 the PC board and lower the assembly into the case The PC board can then be secured to the base of the case using five 6mm long self tapping screws which go into the integral mounting pillars see Fig 2 Now use the remaining five 6mm self tapping screws to fasten the rear panel to the five dual RCA phono sockets CON6 to CON10 These screws go through the panel and 5 Band Code 1 red red black red brown brown black black red brown brown black black brown brown orange white black black brown brown black black black brown 15 3313WVIQ WwG Z 1 3IOH 3313WVIQ UJ 3 STIOH d313WVIQ Ug d STOH 3313WVIQ Uug 9 STIOH d313WVIQ Uug z 4 S3IOH d313WVIQ Ug e W S3IOH Br I 01 14 8 gt l Enea our ae TS es mee a 914 Y gt lt Y 1 lt Y i lt 7 i SSO Ie ON OOOQODO s S3413WITIIW NI SNOISN3WIG TIV 9 uk LLL muss Sa pes c mc lS O 1INYd B INOX SLAdNI OACIA OR POE BE tS JJYNOS AV 13NNVH Y H3MOd aojoojog Ap ALL shown directly above while at right are the drilling Fig 3 the full size front and rear panel artwork is details for these panels w T 2 2 Q e C eed T 3 V S
215. uild a variety of increasingly sophisticated computer controlled robots using the brilliant Lego Mindstorms Robotic Invention System RIS Initially covers fundamental building techniques and mechanics needed to construct strong and efficient robots using the various click together components supplied in the basic RIS kit explains in simple terms how the brain of the robot may be programmed on screen using a PC and zapped to the robot over an infra red link Also shows how a more sophisticated Windows programming language such as Visual BASIC may be used to control the robots Detailed building and programming instructions provided including numerous step by step photographs 288 pages Large Format Rop GRAL 14 99 MORE ADVANCED ROBOTICS WITH LEGO MINDSTORMS Robert Penfold Shows the reader how to extendthecapabilitiesofthe brillant Lego Mindstorms Robotic Invention System RIS by using lego s own accessories and some simple home constructed units You will be able to build robots that can provide you with waiter service when you clap your hands perform tricks see and 264 pages avoid objects by using bats radar or accurately follow a line marked on the floor Learn to use additional types of sensors including rotation light temperature sound and ultrasonic and also explore the possibilities provided by using an additional third motor For the less experienced RCX code programs accompan
216. uk Payments must be by card or in Sterling cheque or bank draft drawn on a UK bank Normally supplied within seven days of receipt of order INTERFACE By Robert Penfold ACCESSING SERIAL PORTS HIS month we continue with accessing l the serial ports which can be either the conventional or the USB variety using Visual BASIC 6 0 or a more modern version such as Visual BASIC 2005 or 2008 None of the information provided here applies to Visual BASIC NET which lacks the MSCOMM component of Visual BASIC 6 0 and does not have the SerialPort component of Visual BASIC 2005 8 either It lacks any built in support for serial ports and it is necessary to upgrade to a more recent version in order to obtain this support Surprisingly perhaps it is not possible to use MSCOMM with Visual BASIC NET and trying to do so produces an error message stating that MSCOMM is not licensed for use with that version of Visual BASIC This happens even if a suitable version of Visual BASIC 6 0 is installed on the computer MSCOMM As pointed out in the previous Interface article the MSCOMM and SerialPort components have many similarities but they are not used identically Despite supposed advances in this programming language it is probably fair to say that Visual BASIC 6 0 still represents the best program for writing software for your own PC add ons and we will take a detailed look at serial communications with this program fi
217. ustry 99 plus VAT g Institutional Professional 10 user Network Licence 300 plus VAT Prices for each of the CD ROMs above are Site jicence 0 cc cscs sc cccccnceccecenees 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 17 596 to plus VAT prices 61 Supports PlCmicro microcontrollers with A D converters Can be powered by USB no power supply required HARDWARE c bat lt d A E SOFTWARE FOR 16 Series PlCmicro Version 4 The C for PlCmicro microcontrollers CD ROM is designed for students and professionals who need to learn how to program embedded microcontrollers in C The CD contains a course as well as all the software tools needed to create Hex code for a wide range of PICmicro devices including a full C compiler for a wide range of PIlCmicro devices Although the course focuses on the use of the PlCmicro microcontrollers this CD ROM will provide a good grounding in C programming for any microcontroller e Complete course in C as wel as C programming for PlCmicro microcontrollers e Highly interactive course e Virtual C PlCmicro improves understanding e Includes a C compiler for a wide range of PlCmicro devices e Includes full Integrated Development Environment e Includes MPLAB software e Compatible with most PICmicro pro
218. value sent via LCDOUT is not ORed with 48 to convert it to the equivalent ASCII numerical form when numbers are sent for display The value simply specifies the CG RAM s address location at which the symbol is held In the program the command IORLW 48 is bypassed when the user created symbol display flag GRAPHIC bit 0 is set It should be noted that after finishing writing to CG RAM a Display Address such as that made via call LCD1 plus bsf RSLINE 4 must be sent to return the LCD to normal display mode More to think about It is worth experimenting with the commands shown in the LCD command codes table as there are other display control possibilities available Ignore the Function Set option otherwise you could lose control of the LCD until after switching power off and on again The functions available through this option are partly related to the way that LCD is wired to the PIC Everyday Practical Electronics August 2008 Listing 10 2 CHARCT movlw b 01000000 call LCDLIN bsf RSLINE 4 clrf LOOPTA movlw 4 movwt PCLATH movf LOOPTA W call CHRTABLE call LCDOUT incf LOOPTA F movf LOOPTA W xorlw 56 btfss STATUS Z goto CHR clrf PCLATH return ORG H 400 CHRTABLE goes here You might also care to think what routines would need to be added and or changed to allow two human domino players to play together Some aspects would be simple but others might be more complex And a couple of challenges ther
219. visit Microchip s website at www microchip com unio Constructional By JIM ROWE Foule ciannel VAY Salecor Do you have to swap audio video A V cables at the back of your TV set each time you want to switch between your DVD player VCR set top box and camcorder If so this project will solve that problem It lets you select any one of four S video or composite video sources and also switches the accompanying stereo audio or bitstream digital audio HERE ARE PLENTY of audio video A V source selectors avail able off the shelf but here s a low cost unit that you can build yourself It s easy to assemble and you will no longer have to muck about swapping A V cables each time you want to change the video source The unit provides 4 channel switching for both S video and com posite video sources but why not provide for component video and RGB as well And why didn t we allow for switching 5 1 channel or even 7 1 channel audio instead of 10 settling for just stereo Pro Logic or digital bitstream audio There s a simple one word answer to these questions cost If we had provided those extra options the circuit complexity would have grown significantly and the parts to build the selector would probably have cost you 75 or more instead of the 25 or so that this unit will cost In short there had to be a compro mise between providing all of the features anyone might want and mak ing it
220. voltage drop The circuit in Fig 1 does not apply constant current to the LEDs directly so it will not guarantee a perfect brightness match against individual LED variation However this is not the specific issue of concern here If we assume the LEDs in a display are reasonably well matched a stable voltage across the LED and resistor combination of each segment 1s adequate This voltage that is the voltage between points E2 and Cla Clb etc in Fig 1 needs to be constant because the number of LEDs which are on varies We can analyse the circuit to see if this happens but in order to do this we have to know the region of operation for the transistors Table 1 Bipolar transistor regions of operation Base emitter junction bias Forward Forward Reverse Forward Reverse Forward Reverse Reverse TO OTHER SEGMENTS Fig 1 Part of the seven segment LED driver circuit Only two segments of one digit are shown 54 Base collector Region of Comment junction bias operation Saturation Reverse active Forward active Cutoff Switch ON Poor amplifier specialist uses Good amplifier Switch OFF The properties of a transistor in saturation are different from those in what is called the active region of operation It is the active region which is usually used for amplifiers and here we have the familiar situation of the collector current being equal to the base current times the gain typically one or two hundred ti
221. w that the display appears to flicker due to the time it takes to completely refresh the entire panel Computer monitors typically operate at a 60Hz to 80Hz refresh rate In our example we will run slightly less than this 30Hz That is to say each row will be re drawn 30 times a second This produces a slight flicker but as you will not be viewing documents using this panel it will not be a problem and we do not over burden our processor With a display panel of 32 x 32 LEDs a refresh rate of 30Hz means that each row must be displayed for approximately Ims Until we have written the software we will not know just how long it will take to write the information to the display but we now know that we must add a small delay after writing each row to ensure that the time between displaying each row is Ims In fact it takes about 400us at 32MHz to perform all the actions required to update a row of data Therefore the delay routine in this example consumes about 600us to give an overall time of Ims Circuit The circuit diagram for the multiplexed LED panel is shown in Fig 2 Now we can Everyday Practical Electronics August 2008 COLUMN 4 LED PANEL Fig 1 Logical connections between a processor and a to even register the multiplexed display see where the port expander ICs come in handy This circuit requires 64 output pins to drive the 1024 LEDs Those output pins are provided by four MCP23S17 port expander chips
222. wn from a given mains outlet This outputs an AC voltage proportional in amplitude to the current being drawn SEE TEXT HALL EFFECT TRANSDUCER RS 286 311 The signal is DC coupled to OV via resistor R11 and AC coupled by capacitor C12 to the op amp amplifying stage around IC4 The gain given by this stage is set at a little over x2 by the values of resistors R12 and R13 Mid way bias is provided by the potential divider formed by R14 and R15 with C13 providing stability ADC TEST SEE TEXT Ce The resulting signal is half wave rectified by D4 and smoothed by C14 in conjunction with R16 The final output is fed to an analogue to digital conversion ADC facility provided via a PIC microcontoller IC1 Preset VR2 when coupled into the circuit can be used to test the ADC conversion when the current transducer is not connected No physical amplitude or biassing controls are pro vided on the printed circuit board PCB These con trols are provided in the PC software Power supply Also shown in Fig 2 is the power supply circuit for a single mains monitor module A PCB mounted mains transformer T1 produces twin outputs at 12V AC These are full wave rectified by REC1 which results in approximate ly 20V DC unloaded on smoothing capacitors C4 and C9 Zener diodes D2 and D3 buffered by resistors R9 and R10 regulate the RAO AMPS IC1 PIN2 Fig 2 Mains monitoring circuit diagram This als
223. y more This enables other programs to access the port Operating the command button will have no obvious effect unless you then operate the slider of the scrollbar The program will then try to access a closed port and an error message will be produced Receiving data Receiving data is not quite as straightforward as transmitting it but it is reasonably simple using the MSComm component The transmitter program is easily modified to receive data as well and it then provides an easy means of checking that data is being sent Form1 246 CLOSE Fig 3 A high value has been set on the slider and the display shows the appropriate value has been read from the serial port Fig 2 A link between pins 2 and 3 of the serial port enables transmitted data to be read and displayed Removing the link will freeze the display and received properly by the serial port Linking the TXD and RXD terminals of the serial port Fig 2 enables the program to read the bytes of data sent using the transmission section A label must be added to the form so that there is somewhere for the received values to be displayed The routine for the form must be modified and this is the new version Private Sub Form_Load Dim SerData As String MSComm1 RThreshold 1 MSComml InputLen 1 MSComml InputMode comInputModeText MSComm1 PortOpen True End Sub This short routine for the MSComm prints received values on the label component
224. y most of the featured robots However the more adventurous reader is also shown how to write programs using Microsoft s VisualBASIC running with the ActiveX control Spirit OCX that is provided with the RIS kit Detailed building instructions are provided for the featured robots including numerous step by step photographs The designs include rover vehicles a virtual pet a robot arm an intelligent sweet dispenser and a colour conscious robot that will try to grab objects of a specific colour Order code BP902 14 99 THE PIC MICROCONTROLLER YOUR PERSONAL INTRODUCTORY COURSE THIRD EDITION John Morton Discover the potential of the PIC microcontroller through graded projects this book could revolutionise your electronics construction work A uniquely concise and practical guide to getting up and running with the PIC Microcontroller The PIC is one of the most popular of the microcontrollers that are transforming electronic project work and product design Assuming no prior knowledge of microcontrollers and introducing the PICs capabilities through simple projects this book is ideal for use in schools and colleges It is the ideal introduction for students teachers technicians and electronics enthusiasts The step by step explanations make it ideal for self study too this is not a reference book you start work with the PIC straight away The revised third edition covers the popular reprogrammable Flash PICs 16F54
225. ystems used the transducers available motors actuators and the circuits to drive them Case study material including the NASA Mars Rover the Milford Spider and the Furby is used to show how practical robotic systems are designed The result is a highly stimulating resource that will make learning and building robotics and mechatronic systems easier The Institutional versions have additional worksheets and multiple choice questions e Interactive Virtual Laboratories e Little previous knowledge required e Mathematics is kept to a minimum and all calculations are explained e Clear circuit simulations 60 Everyday Practical Electronics August 2008 PiCmicro TUTORIALS AND PROGRAMMING VERSION 3 PiCmicro MCU development board Suitable for use with the three software packages listed below This flexible development board allows students to learn both how to program PlCmicro microcontrollers as well as program a range of 8 18 28 and 40 pin devices from the 12 16 and 18 series PlCmicro 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 e Makes it easier to develop PlCmicro projects e Supports low cost Flash programmable PlCmicro devices Fully featured integrated displays 16 individual l e d s quad 7 segment display and alphanu

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