February 2005 E3.7G WWW. af alrtQi'Ble c rm Jiics , ed.u k ifii iV-« ki 1 1 r id - *WM ill i he leaders in PiC development EASE OF USE All you need to get started with PIC Industry standard/quality board Open the box and get coding Available with C compiler or use our PicScript to write programs using simple commands*.. NO ASSEMBLER, NO COMPILER, JUST WRITE AND RUN AUTOMATION SCRfPTABIUTY PicDev Board with PicScript £ 99.00 (plus p+p) This is a complete development suite for the novice or non programmer. It is shipped with: . PicDev Board * PieSheii and PicScript software * Breakout board * Cables * Example scripts Boili items rvtj ui rc r f’ (J nnjer: * PC wiih sen at peri jViiit.ibk' * Power supply adajpkr www.pa^teco nk PicDev Board with C Compiler £ 165.00 (plus p+p) This is a complete development suite for the more advanced programmer. It is shipped with: * PicDev Board ■ PieSheii and PicScript software * C co m p i I e r - Breakout board * Cables ■ Example scripts ICD1 siless^pjigm.L-u.Ljk Tel: -44 (0)1 792 89L927 Bn rrw-a ma it High performance Electronic Projects for Cars Book - Silicon Chip Publications (Australia's i ending Etectnmit: Hobbyist Magazine- Publisher) 05-5030 Alt The Instruction, and morel It showy m full (dour, the conilnEticd modules, has rnou avcrEay diagrams, detailed build guides, ami fitting instructions. It also includes chapters on how engine management works, artvanreil engine HiaitigEnw^ electronic car systems like ABS and traction control, DIY electronic ■HOtilficeLkm, Olid mure! Jt Is a definitive m List- ha i. 1 e it y o-.j ere building any nF these kit;, nr would just like to know how youi car's electronics work. Over 150 pages! ->> W www.jaycarelectronics.co.uk 0800 032 7241 (Monday - Friday 09.00 to 17.30 GMT + 10 hours only) For those that want to write: 1DQ Siiverwater Rd Silverwater NSW 2128 Sydney Australia A Cheap Nitrous Fuel Mixture Controller KC-5 3S2 £7.25 NitrOUS oxide systems can bu Expensive to set up, but now you can da it For much less, This project pulses d fuel Injector M Ct pICtLd I'dEf, adding ii Fixed amount nl nitrous fuel when you activate jt- It will save you a bundle an dedicated fuel solenoids and juts. It cun also be used to control electronic water pumps, coaling Fans, and more. Kit supplied with PCS and .ill elect tonic components. .'sc check local Jaws regarding the use of Nitrous Oxide systems Its your vehicle. Theremin Synthesiser AM-4025 £27,25 This Is a built up Theremin from Jaycar frit, The Theremin is fl weird musical instrument that was Invented early last century hut is still used today. The Reach Boys hit: 'Good Vibrations" featured the Theremin;. You can have one of these kits (cat no KC-529S) For £12.95, All kits have first dass instructions written in clear English text with plenty of illustrations and component identification. jnycnr No, not at all? The hnhby electronics irunfcel in Australia has been hlLturicaily very strong with targe numbers of enthusiasts serviced by dynamic electronic magazines and vigorous commercial suppliers. Tlie most dominant company in this Oown Under' 1 market, Jaycar Electronics, h now in a position to offer its groat range af products ip a wider audience, thanks to the Internet, Concerned about dealing on the Internet? Weil, you should be. At the same time, the amount of legitimate iruej-net trade exceed*! (he fraudulent trade by millions and millions to one. World internet trade today easily exceeds the Grass National Product pF many large countries! Jaycar has been doing business an the Internet now foi ova. ID years. I lie thousands oi happy repeat customers on our files is a testimony to how safe 1 it can be when you deal with a reliable supplier like us. Worried about freight costs? NO NEED with our great rales. Moreinf 1 ? www hi year elect! omcs.cu. uk Check our website! * Entire Jaycar 2QQT Catalogue on-line - aver 6000 products ■ 128- bit 5 e cure an-llne ordering - safe & strut u. 1 Express cm dot mg. * Search by category, keyword or catalogue number, ft advanced search. ■ Over 3500 product datasheets & application nates avail able on-line. 2004 Catalogue - all 424 pages Wo Skive primed this year our Jaycar 2QQ4 catalogue in UK pounds. It Is crammed packed with over 6000 exciting products You can gel one FREE by tagging an fa aur website ,ktd filling aut tilt? entatagup request fprm at '.wiw.jaynjFelcclrajiiaM.uWGlUjlogiie We Stock: ■ A huge range of ex riling kits - A great range of robotic components ■ Tilt.- best tango Of electronic ca in p clients ■ The larges* tingle source range of gadgets ' Security, Surveillance, Aedlo/Video, Lighting, Computer ft Telecoms Fans etc. ( 'TO DrDAQ Data Output - - Resistance pottage Light level Temperature Microphone External sensors: Humidity Temperature 02 in Air Reed Switch • Low cost^jjnder £60 • Built in sensors for light, temperature and sound (level and waveforms) • Use DrDAQ to capture fast signals • Outputs for control experiments • Supplied with both PicoScope (oscilloscope) and PicoLog (data logging) software For more information on DrOAQ r please visit: www.picotech.com/drdaq112 Scope and spectrum analyser functions A fraction of the cost .of benchtop scope Save multiple setups, for ease of use Save, print and e-mail your traces FREE technical support for life FREE software and upgrades f Automated measurements I MrfcjJ JnitnJJFfE’Ul For more information on our scopes, please visit: / www.picotech.com/3cope24 1 Tel: 01480 396395 Fax: 01480 396296 E-mail: sales@picotech.com - »■ 1 s* >L jtf L: * - e •i™ =3 «= w t| RFID frenzy Way back in November 1998 we already published an exten- sive article about active RFIDs — chips ibiat can be interrogat- ed over radio. Since then no major changes have been seen tn RFID technology, and yel the popular press now seems to have discovered RFIDs for the first lime. The articles are almost invariably grossly inaccurate when it comes to technology, one reporter even claiming that all RFIDs 'radiate waves' and by Iheir sheer numbers present a serious health hazard. Initially I wondered what could have triggered this Sudden interest in a technology that's been around for olmosl 30 years but I hen realized that the late si in active RFI0 equipmenl fits 'Big Brother' scenarios perfectly. Recently a critical limit mu si have been exceeded in customer concern about privacy. Traditionally, RFIDs are applied in logistics fgoads trackihg) and security systems, for instance, the ignition immobilizer controlled by your car key Today's use of RFIDs in the retail trade heralds o new era: RFIDs □re Invading our daily lives. As opposed to 'personal' dola carriers like swipe and chip cards, RFIDs can be read and even overwritten From a distance and without the customer noticing. Lots of things con be RFID'ed invisibly: goods and packaging materials, ID cards, plastic cards and even ban! notes according to o recent study carried out by the European Bonk There seem to be no limits to what ultra-miniature RFIDs wish sub 1-mm2 surface areas can da, excepl being traced easily! The same applies io the latest radio bugs employing spread-spectrum techniques and consequently being almost impossible to discover — sen the article Wireless Connectivity' in this issue. Curiously, I do not read about «he latest in RF bug technolo- gies in ihe popular press, despite the fact lhat RF energy Is radiated almost consSartlly whereas an RFID is silent until interrogated by a nearby transmitter. I must be reading the wrong papers. Jan Bulling, Editor lalektor lecronics Volume 3 1 1 Number 340. Foil ruary 2005 i 5 h M 45 ! ‘ ) Ehktor E/eclronfcs aims at inspiring people to master electronics .it .my persona) level by presenting construction projects and spotting developments in electronics and inter matter technology HfeJiar Etelltna a pfLx.ljLaiJ mi Ekenr ftstlranu (IVfehngjL 130. SkH 1 5(1. AVY E^-ind T ? ! g-H4)(tyl 530 200657, i . En-ul-sye : e 1 !:- . j : The « xraiiZfe ktim n bocisrocrj ind eocLrcrTvo out- i2£i, CM Crfl S±jS£nfJlflrt Ltiw Lxrrrzr- ,:s (1 pu£ftr>lri I ! htb 3 . ^ 7. a bOu&i £=U£ Jor ju-V 6. AtUJi SL UrtOKr tfift EWJlV J.“4 Drifcn-' it* r-.agsi.nr via in Fur-tPL. G&rfvar ard LCtit- Tbjjei^kr wdi Ira tvi&sd «Kcns ilia a cn mcu!a bqn - — -i-r thi r V 2 £F,”-~ :rs. IrtCEinjliCulil Editor • .1 Edltw; j a B . i ■ InUfEi^lionit ttfimul vUfT H btt BagK-n. D=v4 Caarnen F<: ’ G= .at do - f rr.,- ^trrijdmter, Gjy Rar'Jarsdr.-i IMp fet! Wimwl erf Ton Gratwlf. FW GgoOCTC, Luc LjKTWT'flns P30 con ducJrve ports can be touched 1 when the circuil h in use ' w s should have added: The circuit pd wared by the proposed supply must bo NiCd battery advantages Dear Editor — ycur reply to Mr. Price's letter NiCd batter- ies — environ m ent vs, quick profits' in Mailbox, November 2004 should have included □ ward or two about significant advantages of NiCd colls over NiMH and other battery technologies. For one thing, NiCd batteries can operate over o large tem- perature range This advantage is often exploited in emer- gency lighting unite that must be relied upon to keep work- ing at ambient temperatures approaching 70 degrees C. At such temperatures NiCd battery has hardly any capacity, Also, NiCd batteries con handle heavier loads., which is a 'must' not only in power tools like cordless drills but also in RC models. These characteristics are not (yei) equalled by NiMH batteries. Converting a cordless drill to run from NiMH batteries is sure to end in disappointment. In most coses, replacing NiCd bat- caunlorparte is ^ certainly advantageous, but the above examples ga to show that ihtrt there are a number of applications where NiCd techno! ogy continues So 'rule'. In these case?, replacing the battery pack by a NiMH version requires a complete redesign. My reply is not intended -as q plea O® for the continued use of environ men- 1 tolly hostile NiCd balled es, but la supply factual information for an inter- esting debate Mark V^rmeulert (Netherlands} Tfi;,r additions ore much appi ecru ted, Any n & L . v-ews-- mcarparated in the Same, electrically safe, enclosure as the supply in such a way thait no comporFenf can be touched, Never, under any circumstances, should the proposed sup- ply be used fo power external circuits requiring a supply of $ volts. The mpguarie editors end de lin.n srs opnfogfzc- u: WGS Crredly for thii omtesfon and warn me* periented renders not to attempt by tiding this circuil. We ore grateful to Messrs R 8 White f, king? ton upon Thames J und P Upscomitc {Partsn;nu'h} for blinking thh safety hazard to our attention Vehicle Battery Jogger Dear Jan — I downloaded the PCB layout for the Battery Jogger from your webssie, and I in ink it contains an error, t behove I he connection from the positive [+) con nec- tar to the discharge resistor is much lao thin for the current invofved. Kare Dorm Hansen (Denmark} 211 llektors Dear Editor — 3 am clearing out my magazines. I have copies of fleCtor magazine from issue 1 to 211 Are you or any of your readers inter- ested in ih-em? One condition is that iF so rhey must be col Karel Wa/rove-n replies — il a continuous cut ami of 40 A would t.'bw, Ate frock Surely would burn aur However, de duty cycle cti toe signal being very smell the PL 8 (rack will easily survive ihe average current We did this on purpose because r 1 acts as a fuse -5ee ai'so ‘Exploding Bite' in lost month's Alatidcn DC I PLC goes Internet Mr. Ivo db Coni nek, designer of i he popular DC! PLC (ftiektor flectronjcs June 200 1 1 kindly advised us that he i? busy writing schwa re lb at will enable th-e entire PLC to be accessed from a PC using web pages. The hard- ware Imk C Formed by the Ethernet network extension earn of the EfaJttor ffectr-onrcs Micro Web Server Lluty/ August 2004}. Further information an hllg ; / /ho rnt- . scarle I be/ -dc I T cd/dcieth,hfml 3 elslusr dftfircxi - 7/2005 lected From my homo in Hemel Hempstead. Mike Pearson [UK| /nffirr:tf=fj render* please contact i 1 .Hi- Editor for Mike's contact details. Connector parts (3) Dear Editor — In the December 2004 Mailbox, Richard Austin was looking For some plugs and a reply was published in January 2005. Far years I Have beer, using Malex umls, and cutting She mullrway ones into smaller sizes with o sharp knife. Say gettrng the biggest 1 1 6 ways] and cuffing I hem ro whatever size I needed inis saved having lo keep a whale lot oF sizes | ha I were never what you wanted on the day A scalpel works fine to cut and irim off any excess and yes you effectively lose one hole when you cut it. I always crimp (he 'wire, using a small pair of needle nosed pliers to shut I he crimp over the wire, then o pan of sidecuhers to give a final squeeze Don't solder them because this creates a sharp physical transition and the wi?'-: can be broken if if is flexed. This has been used success fully on commercioS jobs that ore itill going till this day Far net) bus Mutex socket 772GS, 26AWG, 1 6-way, P/N US 623 @ 6.67 %NZ. Afsa from Fornell a crimp tool, P/N 1 47-124 ' & 45.33 SNZ, Alternatively. TYCO HE 14 system socket, single row, 12-way, Farnell P/N 429- 640 © 3.96 $NZ. Crimp ter- minals, Farnell P/N 429- 703 p etc. These are numbers ligm the Australasian, i.e.. New Zealand catalogue, sourced from Australia. I om s Finding some photos across. RiulSSfdE Stevens (New Zealand] Armed with tha information Rus- s elf kindly supplied, reudafi should he obh to icxirce these ’elusive' connector; from their national Famed tapresantalives. Ear Boggle Hi Jon — was interested lo read Rev, Thomas Scarborough's kitchen table project Tor Boggle' in the November 2004 issue of Eiektor Electronics. I will probably build this audtiory illusion os a bit of Fun, If you want to hear another example of this process, lis- ten lo any recording of Tchaikovsky's 6th Symphony The tune you hear h nol played by any instrument, but 'bounces' between the first ond second violins making good use of the d idiotic eFfecl, Alan Jones thanks far that Atari, I'm sure tnfW&f&d rsaefers will core to get out rfrer Tchaikovsky records or CD; and check the effect uf fnis Easter Egg Russian Relief Dear Editor — I would ike to ask fdektar idee frames read ors who are replacing thair mobile phones, or hove in their cupboard an old mobile phone and charger, PDA ond ex pried SIMM cards, to donate them to us behalf of Russian Relief Ic help the Jess fortunate children. Some can be used by ambu- lance crews and doctors in remote areas, others lor emergency use by people who are m various farms of danger lo summon assis- tance. Some phones can now be used to moke emergency colts even if they hove been disconnected from a network. Used loser printer and mk-jei cartridges can also be Ucdtt0E> (|1 KjtiGei'ir Ctinr&spofl dCrKPEi .5 Eil Ehu discretion oF me Erton*. - Viewpoint expressed by ctHTsa- pcmdenls .-U'E iit?l nuceEUrity r.css lf! ch e- ErJitnr n? Fun-i?nf' - Correspondence may Pa srsnstared ■rr fj'j iedtor Isnysh, dsrdy arid style- - When ivplymn 13 M-i .Lm* CXiTtc scon i h.'iicu, p’eas* quota Issue number. - Pi-es-le =snd WeiIBoj ooire- sponda-nc® to: ad-lorg'S :&Hc7-e!Ec-lTc >vrS rc uk or Eteiiior ErsctronFos, Tns EdiEci, P.Q. Box 190. TunbrrbQE! \V? r ls TW-5 TVft Eng and. J;?‘J35-«W*;-r tlrri’pi-P 9 news & new products World's smallest microcontroller Microchip hcs inUaducud revo- lutionary 6-pin ihFn=K devices in On ultra-small form factor SOT-23 package* TIig^j devices provide on ideal solution for many ma* ■e![ and uses f>ol rypi tally served by mi cito controllers today, including ‘electronic glue' to enable, for example, acniy bug hxes far ASIC emu printed LiiLuif board (FCft) designs, and to replace standard loan; and Hming compoticmls oi traditional mention i a- timers nnri : ■■. tches. The PIC T OF 8 bit Flash mfcracoiv troi'?r family debuts with lour members [PICI0F2OQ, F1C10F2O2. P1C1GF204 and FIC1QF206] I hot offer 256 or 5 1 2 instructions f 1 2 bit program words! of Flash program men-, cry and i 6 bytes to 24 by’es nf data RAM memory These devices also fea-une a precisior, & MHz mi nr no I oscillator 33 instructions, ivyo slack ieve’s, 25 milli Amp source/ sink current I/O. FdW power |1 CO nnrmAjnp) sleep cursenf, a wide operoting voltage range from 2- to 5,5- volts, one B-hil timer, □ watch dog timer. In Circuit Serial Pro- gramming [IC5f'"| techrvdogy power -on ra=ei powersaving sleep mode and (in the PiClOF204 and PIC 1 0F2Q6 anlyl yu analogue comparator module With only six pins, I iuy are extremely easy to use and have a short I earn mg curve far anyone not experienced In designing with microcontrollers Hi rough ICSP technology. Microchip's frpin devices con ba programmed after pheement on a ti; c u it i n rd 1C 57 lechnaEagy enables field-upgrade^. system calibration during manufactoring and the addition of unique iden tihration codes to the system ihe TIC 1 Of family is supparted by Microchips world-class devel upmenl tools, including I he MPlAB ' I n-(_ lieu i ’ Debugger (ICO 2) development tool. The MPiAB ICD2 is o powerful, bw- cost run time tool ibql ulferj cost uffcclivu in-riicuil flash program- ming nnrf debugging fram the graphical user interface of ihe fiea MP1AEJ Integra tod Develop men? Enviranmenl [IDE] software, shis enables a designer Jo develop and deb ug source code by watching variables, single- s repping and setting break points, Running at full speed enables hardware tests in real- time. The MPtAB ICD2 uses □ header board module to support the new FECI OF family The PIC30F200, PIC I Of 202. PJC10F204 ond PIC I OF 206 are offered In 6 pin SOT 2 3 packages . Ariiww Mlwod^p Tedinology LfcL, Mkrntltip Home, 505 fkidde R!m 4 Wmerslr Triangle, WukingHnnt RG41 STU TeL (+441 (Oil 18 921 5858. fa i [+44) (01118 m 5A35. www inkradiy.roig. FireWire audio chip opens the way to affordable, high quality external sound Providing PC and Mac'’ plat- forms with up to eight oud o out pul and now two audio in pul channels v?? • Furifier /n, formation from www gnoeggn^ rgr; Figure 3. d.na r g.nn of rns SiM I. DO. 13 2/i50i dbinr litttusiQ Wireless Con Stefan Tauschek Wi reless data communication is the blest rage. From wireless mice to Formula- 1 telemetry systems, digital radio systems are used in many applications, and they are penetrating into many new areas. In this article, we examine the current state of affairs in the 'airwave jungle'. UT> n s )J> Q Cl cfl zn Lj M oj Itt fi □ >/l □ o to 0^0:0 iO 13 T- w w n w w figure 1, An r-.rc?r pt front the mrea'riorjLwia/ frequency ollc-: aNon JtoWe ISM - 2450 G : 50 M Hi 3 GHz ui ID in i n id Lfr WFl T i£t ■- r> OJ. 3 OJ a m Q (h- r-- tej B O FJ LfT 413 IA in in in CJ? U3 ld id N N K l£M“ 5.fi f .075 GHr WhX-U The enqrmoui pL>pi/1ti rify of wireless commumcuhan is a direct ten sequence of mtemaJionol agreements to desig- nate certain regions of thf5 radio spectrum as ISM bands', since widespread use of wireless connectivity would otherwise never have been possible. Ine demand for un restricted mobile communication L me driving force behind the rapid development of technologies such as Bluetooth, WLAN, HomreRF, and other new technologies with resplendent names Wher. wo lalk about WLAN or Bluetooth, we're talking about applications employing ISM IBM' stands for Industrial, Scientific &. Medicof', which means radio services in these fields. Thi* fSM bands can b^- used without a licence, -and they are sub- ject to relatively hub regulation. The only restrictions ttsEate to the maximum transmitted power and (naturally) (he bandwidth, which must be kept wrtrun certain limits. ■Besides the trad i lionet! 7 7 -PA Hz (SM band fused for CB rariidj. there are now IBM bands m ike 433 MHz, 8 68 MHz, 7 4 GHz and 5.8 GHz regions-. The currently used bonds and iheii rtdividu-al characteristics are sum- marised in Table 1 Naturally the fact that this ISM bonds are subject ro mini- mal regulation is both a blessing end a curse. As there are no ktlon-s on ike number of tronsmittejs ond no defined protocols, reliable dofa transmission cannot be guaranteed if simple do!o transit ission techniques are used. The fact that ihe ISM bands must share (he air- woves w ISO MHz Advantages few power consumpiion No persistent interference sources, tew power con- sumption Relatively targe bandwidth, good propaga Mart, moderate price Relative large band- width, law occu- pancy, duty cycle limited to 10% in mail at fee bond Very targe bondwidlh Vciy large avail able bandwidth Disadvan- tages High noise levet duu Id CB radmE. Bandwidth loo small. dif ficufl fa moke qnterma com- pact High occupancy in certain nrea^ (radio amateur-, rodar] More expensive Ilian 434 MHs due lo dual- super he! tech- nology Propagation p u ab- le m s [quasi line-af- sight). interference from microwave ovens Nat yel econam really viohle ratio is obtained when the signal ss recovered, even if fee level of the spread- spectrum information signal is below the general noise floor before recovery. As □ rule of thumb fee increase hr the signafttHtoise ratio coi re- sponds in fee rolta of I ho IransmtlSed bandwidth to the bandwidth of fee information signal. It's hardly any won- der that the militoiy are so Fond of this technique: not only does ,1 allow feem (a send messages undetected, since the radio signals disappear into the noise a k the air- waves, but it also enables them lo obtain considerably Loiter transmission quality than svife conventional sys- tems. Two methods Ear generating spread spectrum signals have come Id prevail, and bath of them ore presently used commercially. Direef Sequence Spread Spectrum (DS55) This technique For increasing I' e bandwidth occupied by the signal is essentially simple: the information signal is modulated by passing its data bit.-, through an uxc'iiHvl:- 2 400-2.465 GHz using simple F5K modulation, and ii contains oil the Sufic Eternal elements [VCDs, mixer and data slicer) needed la can 5 True I n function ol radio sys- tem using only a few additional components. Using D555. it achieves □ sensitivity of -90 dBm which give: ii a f re e-space range of significantly more than 100 mesres in actual: use. [he transceiver is normally used without a transmission protocol, wife tire user data being simply Fed serially Into the Tx input and taken From fee Rx output without any preconditioning or processing Iot data security This is adequate For pumping date over lire airwaves as up ta 1500 Icbil/sec. Although thc- ML2724 is usea in forge quantities far game [tads and wireless lefephonas, 't aEso has more tricks up its sleeve, hs spread 'Spectrum capability makes it multiport-capa- ble, which means that several! Ml 7724 transceivers con communicate with each other concurrently. This copabiL ity is characteristic of all spread-spectrum techniques, end applications such os Bluetooth, WLAN and the like would not be possible wifeour ir JiwQS -dcllci ekifujoidi 15 CW* Figure 2. ;hc 17555 technique btiticl ths data i n a notes- Fi'gnn. 1 fi m \ i ■ 1 1 1 n m ftt ij ■ i 1 tri Ertn Co^VHSU; ■3 M 13 I J43 51301 in i i ■ « l - m : h ■ Ujf la 7S ; fry we 4 r teqwfv iy itzppmg CtthrVr \ txjch I’r.vH.'-: 1 ; >■ ,'o ib*j uh&J hy seieetof rhnmeh Figure .5 Summary of VV1 AN terhniquEi Wireless LAW Technologies Flad to, 'Spread Spectrum B02.ll Slue ron in | 2 ii’L X MiVa "Direct Sequence" FobH-to-imini f E ao2.iih 1 f 02 1 1 J 1 LH-hlus^rl 11 Mba S.SMh,'n IMIbf's 1 MSVK 54 MtVs Zl UtVi 43 MD5 IS Mb'* 35 Uh i 15 SUtVl BPMJfl ■ IS Code Division Multiple Access (CDMAJ With she D5S5 technique, frequency spree-ding is achieved by modulation using a pscudo-noisr- signal. This signal h also called the J PN cade'. 5 ince ii identifies an individual transmitter just like an identification code I he information signal con only be Altered out of the air- waves using the same PN code, wilh all other signals remaining below die noise litnuL This makes M oassible far several L>SSS I ron see iveis using differed PN codes to -hare the some frequency bond and communicate wilii each other concurrently without causing any problems. Thts technique is called ’code division multiple access ’ ICDMAh which essentially rrieans multiple channels using code separation'. Frequency hopping me orher important iechniquo besides I )$5S frequency hopping [FHL As iha best-known representative or this technique, Bluetooth divides the ISM band between 2402 MHz end 2-463.5 MHz into 79 channels, each with a width of f MHz The signal hop.n Ijumps) between channels in a cyclic pattern at the role of T6D0 hops per .'Rcond This mean;* that typical narrow-band interfercnri? sources can cause only minor damage to the transmitted data. Figure 4 shows how several Bluetooth nodes .:on shaft; the same frequency bond using different frequency hopping sequin ces. Jn principle. the trequc-Ficyhopijiriq sequence for the FH technique corresponds Jo She F N coclti for DS55. sinca in each case mutual interference among the Individual nodes is prevented by using a dif ie'ent spread-spectrum sequence for each node. The FH technology used far Bluetooth demand:, quite pre rrse channel frequency settings, with a tolerance at ±75 kHz, and exact compliance with the scheme of hop pmg to a new frequency every 625 ns. Due to these tech nicolly demanding requirements, it look several years of intensive development work before the first single-chip Bluetooth tionsceiver reached the market at a price sml- □ KIr 'or mass consumption pro duels. Wireless local area networks Now that you understand tin techniques described oEkjvo, we can enlighten you a bit regarding the vaii- ous lyp-Rji ol wireless networks currently in use, As can be seen sn Figure 5 frequency hopping is the tech- nique used by Bluetooth and the original primitive WLAN standard, which boors the Itbfi designation J 602. 1 1 '. I he memo recent 802. 1; I n f 802. 1 lb and 602. T ly standards as-.- based on DSSS, since this spread-spectrum technique is cosier to implement. Natu- rally, other typos of radio links using conventional AM or FM modulation con also be used in the I5M bonds; they ore typically used lor applications such os remote garerge-dbor controls and other types remote-action sys- tem fusing i iqr row-band FM), Fourteen yeors after work began on developing the 602.1 1 family of standards, rapidly increasing market penetration oF WLAN products tan be seen in the form of public ‘hot spats' in airports and railway stations as well as wireless networks inside companies. The ranks □ f technology addicts and enthusiastic readers or F/ei;- iar Electronics hove oven anticipated this technology, with same rather remarkable results. What would you say to the idea of a WLAN antenna far less than €5? It's actually quite easy All you need to make a walking directional antenna is an empty tin, a few screws and a coaxial kF connector. This little marvel is called a can tsnnd, which is a combination of can and antenna ( Figure 6; Using inexpensive materials from a DIV 16 ddra ilntewn • 2,-IC-Jj shop, you con build on 802. i I b antenna with o range of more than 50 km, Currently, the most widely usc-d standard is 602. I 1b, which employs I he lirence-Free ISM bond from 2,4000 GH? (o2.4835 GHz using (He D555 Spread- spectrum fechmquo The range is 30-100 m with □ rrans milled power of 500 mW, which is adequate for most applications, dihough the raw.' do to rote of 11 Mhii/s leaves something to be desired since the value obtained In practice is rarely mare thou 4-6 Mbit/s. Art additional drawback arises horn rhe fact rhot in rr,o>t WLAN net- works a large number of clienls want (a Communicate with each alhei, so the number of available channels can be quickly used up The 802. 1 lb standard defines 14 channels with a bandwidth ol 22 M Hz per channel, beginning with channel 1 at 2.412 GHz Channel 2 starts at 2.4 1 7 GHz, offset from channel I by 5 MHz The channels overlap, so they cannot all be used ai the same time in a single network (Figure 7|. II several access points are needed in a WLAN, it is passible to use [far example] channels 1, 7 and 14 concurrently More bandwidfh fhii means we need more bandwidth and more chan neb, The standardisation committee salisfied this need in 1999 wilh the introduction! of ibe 302. 1 let standard It utilises the 5.8 GHz JSM band and employs □ modulation technique called 'orthogonal frequency division multiplex- ing' [OF DM}. This yields a now data rata of 54 Mbd/s, allhoirgh the range is only half os large The total av oil- Figure a IrtBxp.'n 5 iW and emetiw tfie Conseano. i*m Mlu CMsjirvU 1 21 1 2 "!U 22 MHz ClWRIWl 1 1142 Util cmnrwr 1 5 in uhi 2inmir 10433 -:i F lyure 7 MAN <: F.ci.'rr; on?r lap. able bandwidth allocated to this band is 455 MHz, horn 5. ( 50 GHz to 5.725 GHz. Up to 19 non -over lapping chon neb are available, olio wing the some number of access poinls to be used without mutual interference. Two years ogo, the OFDM modulation technique was obo introduced for the ? 4-GH? bond via the- 802. 1 lg standard (2.4-GHz Ot DM PI IV] inis means there arc- presenily three f air interfaces available - 802 1 Io„ Table 2* Radio standards for WLAN and WMAN* Slrmtfqrd Frequency znngc Maximum data rule fMBtl/s) Dulc throygh- puf (MBil/sJ Range (ml SWAP Lk 05/1998 2.4 GHz |ISM| licence free r 1 50 SWAP 2,x. 07/2002 2.4 GHz |ISM| licence free 10 50 002 1 1, suit 1997 2.4 GHz |1SM} licence free- 2 1 30- 300 802.1 la, 09/1999 2.4 GHz IIJ-NlIj licence free 54 22 12-20 802.11a, 09/1999 5 GHz fil-Nll} licence free 54 22 12-20 002,11b, 07/1999 7.4 GHz ,|ISM|| licence tree i i 6 30-300 802 n fl , 06/2003 2,4 GHz {15M| licence free 54 22 20- 100 802.11k 09/2003 5 GHz flJ-Nil} hrence free 54 22 12-20 B02.1 1 n, [anticipated 2tX)5]* * 100-320 802.16, 12/2001 10 66 GHz licence required 134 70 50 k 802.16a, 01/2003 2 1 1 GHz licence required 134 70 50 k 2.4 GHz [l5M) r licence Free 5-6 GHz f l J-Nfl/C F PT| liceiuc free 802. 16&, 2004 2-6 GHz licence required 2 902.20, 2004 10-66 GHz licence required 16 2/0,3 15k HipeiLAN/1 , 07/1998 5 GHz 23.5 20 10 Hiper LAN/2. 04/2000 5 GHz 54 42 50 HiperACCESS 42 GHz 25 n/s 5 k HipurMAN 2-11 GHz ’ 'WMAN' smrid; For Wr re less Metropol-rnn Area Netwcnk' which is □ WLAN For □ relatively 'axgE region (city or district of a cily| A WMAN ii larger than a WLAN but smaller than a WAN (wide area network], Just as lha WiFi Alliance strived (and stil drives] lo achieve co-mpalibitrly end Interoperability for 802 J 1 based WLAN jyilems, the WiMa* forum, founded in 2001 . pur- ine; ihe same objectives far WMAN equipment compliant with the IEEE BD2.16 Family af standards. Staring in 2006-07, WMAN could became a competitor For UMTS. ** Draft version, standard unlikely lo be approved before 2007. 17 2 9005 ■ eklcta Felrunio figure 8. CcwteKruj ccmfnjrfion pi'mrp. 802 1 1 b and (302. 3 lg but they ore to be replaced by 802. i Inin ihu fulure The objective rs lo further increase the da Ice rule to more ihan 300 Mbit/s. This bil aF magic is supposed Ed Ij-u achieved by using transmission proto Cols with greater efficiency, compression techniques, £jnd receivers with improved dynamic c, heir aderistre-s [Table 2; Smart antennas The Confenno shows, lha! it's not that difficult fa make □nlonnoi vyilh good performance foi centimetre wave $.q- nais Even so, Eld sill] common practice lo u.-e rod anten- nas wirh omnidirectional characteristics, -with i3ie msuli t i t TTTTTTTT figure 9 Bearn forming cun r>? Lund to Uirer .thu radio wove j in vtmbuj d‘r actions . . . figure JO. . and s^hetivefy ccmmunfoote >'/•'■ di/fojTL-n. 1 c.re-aj j'n d bur Wing ■>Mr» II L-» | D0rn Inal most of I he emitted Rl energy gt'ie.s unused. That may be o reasonable approach for mobile systems, but in fixed installations ihe transmission distance con be con- siderably increased by us-ng directional antennas. I here ore several 'dosaic' antenna designs that yield direc- tional characlerisErcs, such as Yogi antennas and dipole OFrays. I Eowevei, a much simpler solution is a waveguide closed at one end,, in which a standing wave is gener- ated by suitable mechanical dimensioning, Figure 8 shows (he basic design of such n "tin-can' antenna Here L q is ihe length of the standing wave In ihe antenna {with ffie maximum being located al Lg/4j f and L is ihe wave length of the carrier frequency in bee space. The size of ihe lin and I he Frequency jointly determine (he length of ’he standing wave. Instructions lor building a C-ynlenrra libe this -:in cl the calculation of L. cun be found on numer- ous Internet site s, such as httpt/7www . 1 u rn point , n et/ wire leas/ crjntennahowto.ht ni] and hhpi/./ w w'w. An unal uh tj . f i /e Ic-oa I / a me n no 2 h tm I With careful construction, it is certainly passible to achieve a re-spec table antenna gain. Measurements show in a! the rouge can be increased by at least a Factor of two MIMO Increasing antenna gain by a few decibels is by nn means llte only Irrck that can b^ canjuned oui of the magic hox aF RF technology Multiple input, rnultipleciut put jMJMO) techndugy is also proposed as a means In significantly increase range- and duly roles wi the ut increasing RT power. What lies behind this name is □ sophisticated antenna technology called 'phasadcirray antennas', which originates from radar systems. A pha sed-array antenna consists of a two-dimensional array of dipole elements, which produces a radiation pa Hern with a strongly focussed fobc- IF (hi? dipoles are driven in phase by an RF signal the antenna radiates a p.fonc- w nvt' perpendicular to the cirroy This yields □ con- siderable increase in range and eliminates nrmffipafh effects al the receiver If the relative phases oF the RF signals Fed fo the Individ i, mi dipoles ore modified in a surlable manner ]Fig- are 9 ) fh* direction of the lobe con he sl&ered in almost any desired direction without making any mechanical changes. The only thing ihal is necessary for implement- ing an antenna that can emit a beam al RF waves in almost any desired direction, similar (o ihe beam from a lighthouse (Figure 10 ), is the ability to control the phase re lc tranships of ihe individual elements of the antenna Although this technique does not increase the total amount of energy radiated by ihe Iransmiitei an-tenna (which means if still -com pi re s with the regu la lions], r con- sider ably increases ihe amount oF energy arriving al receiver antenna. Antenna diversity and receiver combining Up to now, we have concenlfared on ihe transmitter end in our eff-nrh !q boast the performance of our WLAN . However, Ml MO aba encompasses Impravemenls a I ihe receiver end !o Faisu ihe latal physical capability of the system The ►rhtial abjective is to solve ihe problem of multipath effects. Especially ir. enclosed spaces, radio waves do not travel la ihe receiver antenna along only one path, bui instead along many differc-nr poll's that result from multiple reflections. The reflected signals are offset in phase from the main signal, and Ihe net result of superimposing the* i affected signals on ihe main signal coil dramatically reduce signal quality arid thus decrease the usable range, This makes antenna position a decisive Factor and changing the pash ion of the antenna by only a few ftenlimelres can be- enough la make good recep- 18 tbkfci dtrironln - f 2&01 lion considerably worse o' dramatically improve poor reception, Fgi this reason, current WLAN implernonea lions already hove two receiver onlenna polhs, which ore demodulated in twa m dependent kF iront ends of the WLAN chip tel For each irantFor [transmit and receive), the baseband controller checks which oF the two paths provides the belter result and selects it ifr be used far Fur- ther processing, This Technique is colled 'antenna diver sstyL Spatial multiplexing Antenna diversity is a i meet exclusively oi improving results fit the receiver end, and it can be used even if the transmitter end has only one antenna. However, ii multi- ple antennas are used til bath ends of the path, even, man.- rah nod lech meal tricks can be used to improve the air interface It s cleas ihai when radio waves in the centimetre-wave range are used far data communications inside a build mg. closuly odjcceni locations can have quite different data ironsscr characteristics. This knowledge can be used to cleverly transform the problem oF multipath reception into a major benefit If al ic-ast two antennas are used tor both transmission and reception, ii con ha r turned thot the two ironsm i [-receive antenna pairs do not use the some path through the aw, but instead two different paths. In theory^ these two transmil-receivo paths can actually be regarded as two separate channels, despite the fact thal they use tFie same carrier frequency, so they con transfer different information and thus double tha bandwidth [Figure 111. In practice, or course ihe hyo Figure ) L M i'.'pie antennas ot each end cart eon i ide.'nJdy intreaie bandwidth . paths da not behave exactly like two mutually isolated channels. Nevertheless, a signiftcani increase m bond widlh con be obtained using this technique, which is called spatial multiplexing' Combination therapy There's a v=ry good t ho net* thot MIMO will be included in Inn upcoming SQ2. 3 I WLAN standard, although Ihe standard is unlikely to be approved before 2007. Never- theless, monufoesurers oF WLAN chip sets, such as Arh eras, are already anticipating the new standard with hew generations of tCs incorporating - pr«4K)2 Tin 1 features. For instance, thu AR50Q5VA chip set ha' all the technical capabilities necessary to allow jt to be made FIG^ M- com pliant by simply updating the driver software alter the standard has been Firmly defined, i he chip set has two RF front ends, so the MIMO tricks described above rein be implemented using two antennas lor the transmit and receive functions. A daia rale of more than 1 00 Mbit/s non already ha achieved using the AR5QQ5VA, which is enough to allow even HDTV vtdeo Jo be transferred aver a wireless network “4H39-1! jAlJywfrwrwrt FRUSTRATED ! Looking lor ICs TRANSISTORS? A phene cal! io us could gel a result We offer mi extensive range and wilh i- world- wide database all nur fingertips, wc -iri- ablc to source even more. We specialist: in devices wilh the billowing prefix no name but n few k 2N IS A 25 B JSC 2SD 2b 25J 2SK. 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X EMC and lysis * -1 free - pc b - softwa re.com 7/2005 tWiar efiaiwja 19 Ton Giesberts rmm, iavAYvv, -38Bs8B2«« suitable high-quality transmitters and lNCj receivers with a ^ wide dynamic range: these are ideal for use wireless microphones. i 4- * [ j |X« L- •1 *1 T^TTJ 1 1*1 • T # JiT [el 1 L ■ 1 1 1 ^ i L *E f» ;* J * w »] l Y* | [^i|| [o B b j ■« [^i | f M W ' * Com pan tier process Th h WA -TX- 01 (t. i ail smiUer ) and W A FlX-fll {receiver) modules represent a novel concept in tho wireless transmis- sion of audio signals. Thanks to low power consumption, Lhe technology lends itself lo a ’.vide range of audio applications The transmitter and the recnivor include tromponemrs such as SAW filters, SAW resonators and noise reduction TCs. These key components allow ihe development of small high-quality audio modules in accordance with European radio regulations and with EMC and RStTTE guidelines. This means that a wireless link can be added ru an audio dp visa without bav mg to worry about a complicated, expensive and time-consuming certifi- cation process The frequency channel i ■:'<••• 1 1 : v each module is fixed* but there are lour separate channels available in the band from £63 MHz to 365 MHz, and so multiple systems can coexist in the same location Dynamic 1 fro ns miss son The maximum sound pressure level (SPL) which can be tolerated by humans ss I -10 dBgp^, which is measured rela- tive to the minimum audible sound piessimi level of Od0,- F , - 2D pFo. In a quiet room the background nosso level is about SO dB^, and the sound pres- sure level of the human voice is around 120 dBspL- It can therefore he seen that the dynamic range required for a nor- mal wireless audio transmission sys- tem is around 100 dB If an audio frequency of 15 kHz is transmitted using analogue frequency modulation, the required bandwidth ( B W ,i L5 given by BW = 2 (maximum frequency deviation *■ maximum modulation frequency) |Hz] Hnfai innately any FM circuit must sut- ler from residual sideband noise origi- nating tn the PLL or crystal oscillator. As a rule oi thumb, r .vo can reckon with a residual noise, measured m terms of frequency shift, of around 50 Hz Fbr a dynamic range of 100 d!3 (i.e., a factni of 100 DG0) we therefore need an over all frequency deviation of 50 ■ 100 GOO = 5 MHz. As you might expect, this means that the required bandwidth is much greater then that available in this application. For comparison. FM radio transmissions make do with a Figure I Use of a responder k-r noise reduction. maximum deviation of 75 kHz in a bandwidth of 1EQ kHz {mono) or 204 kHz (stereo plus traffic natal. In order to solve this problem while keeping within the legal restrictions on frequency deviation, a compressor is built into the transmitter and an expander into the receiver This tech ni true ls called a compander noise reduction. system (Figure l}. The Dolby noise reduction ay stem varies tho compression ratho with fre- quency, The compandor noise reduc- tion system used here, on the other hand, fixes tln> compi fusion i at iu at 2:1 over she entire frequency range, thus halving the dynamic range of the srq rial. In the expander, whose ratio is set lo 1:2, Hie exact opposite occurs, and die dynamic range is doubled again. A dynamic range of I GO dH is thus reduced to 50 dB for transmission. We can now recalculate the frequency de viatic i required. With a residual noise of 5Q Hz we need a frequency deviation of b DO Hz for a 20 dB dynamic range* 5 kHz for 4G dB and 20 kHz fur 52 dB, A wireless system with a signaJ-to-noise ratio of 50 dB can cany sound signals with an origi- nal dynamic range of 100 dB. Why, in this "digital age', do we employ analogue transmission tech- niques for the wireless microphone rather than, lor example, PCM? There are several reasons. Many countries have not allocated a dedicated fre- quency band for digital wireless microphones. Digital transmissions using PCM inquire a wide frequency hand, which is not readily avail ah Ee below 1 GHz. Above 1 GHz 'dead spots' start to appear, meaning that these frequencies are not suitable for live use where the per former may move around between various posi- tions on stage. Firs ally, conversion to digital requires much more power, making it less practical to run the device from s.maJJ batteries. It desired, the modules (both receiver and transmitter) can lie operated from xi 1.5 V battery via a low-noise DC -DC converter available from Circuit Desi gin. In nr due i n acl r itt ve the 100 PR dynamic range that is pnsBmle with the wireless microphone, the noise pro- duced by the DC DC converter niuct be lesji than -60 dBm. The WA-DC-01 DC- DC converter requires an input voltage- of at least (1.3 V and ran pro duce an output voltage ot 2 V at the maximum load current of 50 niA. fte fraiiimitter Figure 2 shows the functional blocks of die WA-TJt-Gl transmiuer We wrll look at each Ln turn. input buffer (BUF 1 ) This circuit is an input buffer for tho microphone capsule or other sound signal source. The irtaximum input Level is -lb dBV and The input imped- ance is 7.5 kfl. If the maximum output level of the signal source is not suffi- cient, a low-noise amplifier must lie connected heroro the buffer. If the sig- nal source level is too high, an attenu- ator should be used. 2/IG05 - slitkrr&lrtnln 21 WA-TX 01 Figure 2 iBfock diagram of tl ie transmitter module . . Compressor The audio signal bout the buffer stage ie compressed using a ratio of 2:L The compressor consists oi a reference generator, a fuil wave rectifier and a urn miucj ampli fie r J <:■.•: i ■ i fi :■ r on on g e n - era ten pro titles 3 bras voltage sod a constant current m tin- other parts oi the circuit The full- wave rectifier circuit rectifies the- moon :ng signal with the aid of an external capacitor The output current of the iectrfic -1 controls lbs gain cell -uirplilier The time constant of the con- trol ] olj 1 1 is h h i , in part using an extor- nai filter capacitoi an d an Internal 10 kli [c-cistDr. Th* : . l : n i ■ i ; ■ ■ ij amplifier adds the mooming signal and the signal from the gam coll amplifier together. The summing ampniior used jn the cc oi ores so j needs different properties from die one used in the expander, and so different components are used in the transmitter and m the receiver. Pre- emphasis To reduce noise at the upper end of the audio frequency range r which is □ par- ticular problem when using frequency modulation, this circuit boosts higher frequencies using a time constant oi 50 ps AF low-pass filter (AF LPF) This circuit limits [fie bandwidth of the audio signal in order to ensure that imoifoiMicp to adjacent channels kept within the permitted limits. Oscillator and modulator In ordei to operate directly in ifio EG Cl MHz band, a crystal-based SAW (surface acoustic wave) filter resonator with good temper aim e stability is 05 ed as the oscillating element, Fre- quency modulation is achieved using ■i vnneap ciindn that forms part oi the oscillator circuit. RF power amplifier |PA) This circuit steps the RF output oi the oscillator up to the tsattStait power of airaiit 5 mW. RF low- pass filler {RF LFF) This circuit attenuates the second and higher harmonics of the transmitt od signal ana provides ar term, a imped ance matching. Voltage regulator (AVR) Tins circuk provides a stable ?,7 V sup- ply for the whole circuit. It. operates from a battery supply of between 3 V and 9 V. Fife receiver Tho block diagram of die WA-RX-Gl receiver module shown in Figure 3 in pi acn catty the mi not image oi the transmitter, using similar components , RF band -pass filter (SAW) The SOU MHz frequency band used in this v/irelesB audio system is eirtmcted iimi'cj "r ; filter. A hrgh-sclecTivity SAW WA-RX-01 »r Figure 3. ... and ol ihe ng-ewsr module 22 tlilclw ikrtufiki. VWA 2 ilrei is used to ensure that frequencies outside the hand are eliminated Oscillator (DSC) A quaita crystal oscflteLot is used to mix the incoming signal down to an intermediate frequency of 10.7 MHz. RF amplifier (LNA) A low-noise amplifier is vised to amplify the EDO MHz frequency hand by 10 d B. Mixer (U3X] Tills circuit creates an intermediate fre- quency of 10.7 Mila, u reduced by mix- Lap the amplified received signal in the BOO MHz band with the output of the oscillator IF amplifier [1F1 to IF3] Those provide a total gam of 1QD dfl. the final stage acting as a limiter, Before and after the amplifier chain. 10.7 MHz ceramic filters are fitted to provide selectivity. FM detector (DETJ- Tins circuit demodulates the fre- quencymodulated IF signal. &S5I detector (RSSI) Signals Erom the middle of the IF amplifier chain ate rectified producing a DC voltage proportional to the signal strength. Mutingi comparator (COM) The HBDt signal is compared to a pre- set voltage which can be adjusted using a potentiometer. If the level at the antenna input tells to 17 dBjuv or less, the output signal ss turned ntt De-emphasis This compensates for tho 50 ps pre- emphasis, making the overall fre- quency response of the system Qat, AF amplifier (AF) True r : rcu.it amplifies the demodulated audio signal before st is passed to the exp an dm. Analogue switch (SW) lithe? signal strength tells too ter, the audio signal is muted using this sivitch An LED indicates when this mutiny occurs. Expander The dynamic range of the audio signal is doubled by this circuit, which oper- ates in much the same way as the compressor AF output amplifier (AF) The output of the exp unde i circuit is amplified again for output. Voltage regulator (AVE) This circuit provides the entire cnuinr with a a [able 2 7 V supply fioin a bat- tery voltage of between 3 V and V. Interface Thanks to these complex modules that include almost dll the necessary elec- tronics, what remains is straightfor ward Figure 4 shows the two parts of the circuit in the transmute: we can either connect a microphone or any other desired audio source with a max- imum outpu t level of -l 5 dfi V 5 u mo s t vanes, however, an alec tret micio- phonc will bo uesd. There is a small offset voltage presoni at the AF input with PI adjusted to maximum: in our prototype we measured about D. IS V If ■ j . dynamic microphone is to be con- nected. it is essemtal to arid a coupling capacitor. Alternatively omri R1 arid connect the dynamic microphone in plate of the elect ret microphone. PI can bn used to attenuate microphone signals that are too high, so that the radio module is not overdriven. The receiver circuit is slightly less sim- ple Tire receiver module ha.-. two out- puts, one lot the signal itself and one which indicates whether ibe signal strength is adequate or whether the muring circuit, has been triggered. Since we have plenty cf power to spare at the receiver (battery operation here is not esse- nn al) wa can affoic: an extra indicator in the form of LED Dl. In order to amplify Lire output of the receiver module (which, at 10 kU, is not exactly low impedance)', we have added a buffer amplifier. This is a classi cal non-inverting AC amplifier builL around a rail-to-iail op amp which can operate rmni a voltage of between 2.7 V and 1 2 V, almost the same range as for the module. I'Ve have shown a supply voltage of 5 V, although 3 V or 12 V would do just as well. IE a - iiifterenl (mm- rad-iQ-raill opamp wore used, a supply voltage of 5 V would bo required. Many c | lamps will only operate correctly with h symmetric power supply of ±5 V ot Figure J interlaces hr Iks turlb modules,. 7/TiJfiS - tlttiEf itHffran 23 Figure J>, Two circuit board * make cos rudio link COMPONENTS LIST fltisisrofs: Rl 2Yii2 = 560il' = 72 GY.ii R5 - Akn7 R6 = 47U R7 •• 100*0 P I ,P2 ■■ 1 0 V0 pjf?5ti Ctap-tidlqrs; C1,.C6 = 4jjF 7 63Vfadrol C2,C7 = IOOjiT C 3.C5 .C8 IQ|_F 63 V radin- C4 = 470m Sc-mEcofiiduciorsi Dl LED, 3mT> giEen, low currenl D'2 r LED. 3mm, red, lew rurrenl ICT = WATX-QI [CTrcufl Design) IC'2 WA-fiK-O! A [Cucuil Design) IC3 ■■ T592IIN (or eqmvolsfli tail icsrail- opamp) MiieetSonsHaust JH I = 2-way ptnhsoder wilh jumper [angled il naaKiaryl Kl - 3.54HIT1 jaek &a-::icfil PCB mourn |e.g. Conrad flecfroriic!, ft 732093) E1T1 = battery Solder iar Iwo I.SV baltsriis MlCl «r a E-rPe! microphone PCG r nn, D4Q407 E. ovoEIdLIe from Thn PCBShop with. an asymmetric 10 V supply A fur ihei advantage oi theT$S23 used hsie L5 its high output dnve capability: it can directly drive headphones oe even two 32 U headphone transduce! s wired in parallel although in this case C6 should lie replaced by a 100 fih" ID V type? The 47 ii (hi! put resistor protects the op a -up from tbn indirctive Load of a shielded cable and fintn short cl r r. m lt ‘ Tr i rnmer potentiometer P2 allows the gam to hr adjusted flora unity (P2 at minimum resistant >:) to L0 ciB [P2 at niaxunui t resistance). C6 removes any DC compo- nent from tho output ,md R7 ensures tliHi there? Ls always a Joed m r.iin out- put. Since the opamp has asymmetrical supplies, a capaoitot (C5) ts also required m the feedback dmuit R3 and R'l set the operating point .4 tin- opamp at half the supply ventage C7 and CS provide e xtra power supply decoupling At higher supply voltages it is neces- sary to increase the cm rent -li mitin g tes islets For the low - current I FDs so that the current through them denis not exceed about 2 niA, We have designed .1 two-part printed cuciEJE boord to accomiHOdete the radio modules and the tow external uotupo nents (Figure 5j The layout ts designed for optimum audio performance. The components should be hi ted to the board, observing that the transmitter module can only be fitted to the coppe] side An ordinary 3.b mm jack socket provides the audio output All dial remains ore the antennas, fn principle a siiif piece ol wire with length 1/4 /. {73 mm at SlSU MHzS will do the job; more profession til antennas can be found nn the Circuit Design website at hitp;/7w ww.cdt2l .corn/ ivvhqmi 24 eIA^t tbdr^nin V ICb Frequency j?F channels Emission code Range Signal-to-noise ratio Audio Frequency range THD Pre-empF>asis Operating temperature 863.125 MHz 863.625 MHz; B64.500 MHz: 864.875 WHz one (fixed] F3E approx 50 m line-of-sighi 90 dfi (wit+i I H P -A filter] 50 Hz Ho 15 kHz ± 3.5 cfB (output level -50 dBV * 3 dBj 2 % [@ AF I kHz, deviation = I 5 kHz or 7.5 kHz] 50 pa 0 C !o 50 X Transmitter Oscillator SAW oscillator, crystal-based RT power 2 mW Frequency stability ±10 kHz Fre^emphasis 50 ps Naise reduction Compressor Spurious emtssian 1 jjW maximum Devi a ti a n 35 kHz ft kHz $ -26 dBV) Audio input level -315 dBV Jd-] 5 diW (1 kHz) Audio input impedance 5ktt Supply voltage 3 V ta 9 V Maximum module current consumption 25 mA Measured current consumption 17 mA® 3 V Receiver Receiver type SuperheteradynE MtXei DSCilbtar Crystal-can trailed IntimriudiutEj irequency 10.7 MHz hfoisa reduction Expandut Sensitivity 2 ! dBpV (@ THD 2 %f Squelch sensitivity \? dSpV ±4 dB Audio output level ]at module] -20 dBV (deviation = 15 kHz] Maximum - \ 0 dBV [deviation = 30 kHz) Audio autpul impedance [at module] 10 kO Supply valragc 3 Vta 12 V Maximum module curranl consumption 30 mA Measured currenl consumption [D2 on R2 R3 560 ii) 32 m A @ 3 V 40 mA @ 5 V 52 mA @ 9 V Note; 0 d&V = 0.775 V Curve A shows the overall transfer LhorULteristk. ol iiiu entiii* radio Fink, measured ul minimum gain (gremi|| and maximum gain (red). The inpul signal to I lie transmitter was a! -46 dBV [approximately 5 mV| The oulpur signal at maximum gain was al -31 dBV The output signal or I Fie receiver is 5 dB above ihe input level Jo the iron?, mi tier With □ higher input signal level ihe response falls cFf somewhat al higher frequencies, but the ompli rude at 5.5 kHz is up to 3 dB higher than that ot 1 kHz. Curve B shows ifie distal litm [plu-s noisef nS iFie rjuJpul of ihs rncEiver against signal IrvsI rneosuied aver tFie frequency range from 22 Hz Id 22 kHz. Hie upliirium value appears 1o ccclt -vijri -j/i inp-.il signal evd ai ihe Eiurnmittc? of 5 mV. In this case llm input signal is raised from -70 dBV lo -15 dBV with the gain or ihe receiver is at a maximum. This is more Irian ade quote for speech signals Curve C shows the frequency spectrum with rm input signal level □! the transmitter of 5 mV. Mast of the distortion is at rhe seta net harmonic. Fn this case the THDr-N figure h Q.B5 % [aver the frequency range from 22 Hz to 22 kHz}, 2/MH3S - HfcSleK tftrtrwuis 25 300Hz no! olocoled in rhs UK 3k Ht 9- 1 A kHz; radianovigoliott; iKund'Errslorm dc?e;£Si 1 i 9.95 kHz man firm? mobile find, submariimj} 3 6 I- Hz isT service I 9 95 -20 05 - Hz frequency sfgnttai'ds 30kHi The Radio Frequency Spectrum from DC to 30 GHz i in pages Paul Goossens Life without wireless communications is almost unthinkable in the modern world. These days virtually everybody makes use of some type of transmitter or receiver: GSMs, broadcast radio and TV, WLAN, Bluetooth, and so on. And there is still a lot more happening in the radio spectrum. In this article we show what else can be found in 'the ether'. 2* e!;h ;■ d-tm'.-nu - J/JW5 30kHz 40 ItHz JJV (time signal^ Japan] 300kHz 335 - <195 kHz raaionovigcitian 3MHi 50 kHz RT7 (lime signals, Russia] 5263 - 1 506.5 kHz AM & DRM radio [MWj 60 kHz M5F (time signals, England] 1 600 kHz radio amateur < 1 60m) 773 kHz DCF (lime signals, German/) 70 kHz - 130 kHz radianavigatian (NOB) ] 30 - 1 49,5 kHz maritime mab'le 135-137 kH^ amuleur radio 146 . 5 - 783,5 kHz AM radio (long Wave) Over the years, organisations throughout ihe wadd nave allocated certain parts of the radio spectrum for specific applications. An ovarvisw or this allocation con be seen in iha chart at the !op of ihe pages of this article. Hie range that we'Fe looking at here state al about 300 Hz and goers up to an amazing 30 GHz. The chart in a a been divided into eight parte, failed Frequency bonds This division has come about partially due to historical rea- sons and is aha due la decisions made at international conven- tions, Roughly speaking, frequencies in a certain bond seem to have similar physical properties there will of course be same ever- lap of the properties ai the sran^iiion of two bonds Low frequencies Radio signals with lower frequencies are hardly affected by obsta cles such as buildings and trees, compared to signals with higher fre- quencies. The higher (he Frequency the morn the signal wifi bo ahen- uated by obsta cles, Another useful choroderistio of signals wilh frequencies up to about 30 kHz is that they fend to fa'll ovr thn curvature of the Larin. Since the aerials are rarely much higher I ban ihe correspond tog wave- length, the Eorlh pfuys on important rule in the signal propagation. In this situation il is nc longer necessary lor the transmitting and receiving aerials to 'i&e‘ each other. Broadcasting One at the best known uses of Tadio com mun kalians must surely be broadcast radio, Until now the most common modulation typos used far this have been AM arid LM. Three parts of the spectrum are reserved far AM radio: the long wove (IW|. medium wave (MW) ood shortwave (5W) bands. Of ihe sc, the shortwave (SW) is still used the most because depend- ing on propagation ’hi 5 band is suitable For worldwide trommci ni- cotians Because? of ihe higher Frequencies (formally, between 1.6065 MHz and 30.00 MHz), grounrfwave propagation no longer plays an im par font role and these signals hardly follow ihe curvature af ihe Earth. But it is still possible So receive world service stations on distant shares and fa receive stations from ihe other side of the world in fhis country. Inis is mode possible by a certain olmaspheric layer, cabled 1 In- ionosphere This layer reflect* radio waves from the short wave band. The radio station transmirs a very powerful signal (1 5 la 120 kWlf a* on angle towards the ionosphere I his angle is chej- seri in such c way that iSih radio waves are reflected Eu the required area c-n the globe where they can I hen be received, the majority of people tend to associate LW/MW/SW witfi ihe pas I a id instead listen to FM radio (07.5 to 106 MHz]. The sound quality af (he*e transmissions is much butler than ihose on ihe 'AM' bonds. FM transmitters often a:=o provide extra services like RD5 (radio doit.: system), For example, a cor radio con automatically switch to a different stalmn jhroodcaslmg ihe same programme] when ihe recepliun c-n dir currenl slogan worsens. Another service automatic oily stops ihe CD or cassette player and switches So the radio whenever a traffic announcement is mode. A recent development in the broadcast wodd is ihe transmission of diylql radio signals [DEM] m tho shortwave bonds. This allows data as well os audio to be Included in n broadcast. It is therefore likely that various extra services will be introduced in shortwave broadcasts. This is a subject that we J ve covered before in E/uktor E/edranrcs In ihe March 2004 issue we published □ design For a digital short- wave radio receiver (DRM receiver] there are currently also digital radio Iransmissians ( 0 AEs r Digital Audio Broaden sling |, which are on alternative 10 ordinary FM 1 Lidia., The some development is taking place in television; the con- ventional analogue transmissions [which take up a fairly large parr af the spectrum] will eventually be replaced by digital television (QVBT. Terrestrial Digital Video Broadcasting). An Improvement in quality is nol the only advantage of ihe swilch to digital technol- ogy. The available spectrum is utilised moreeffscienily because sav ernl channels can now be placed in the same section of (he spec- trum. This development has already happened with satellite TV: apart from the original analogue IV satellite;, you'll Find lhal most mod- ern satellite transmissions aie* now digital. Professional communications Apart From radio and television broa dec sling, there are many more applications where radio rs used fen the exchange of information. Just In ink af the- coir mu nicotians in avfolfan. shipp. ng, the po! ce, etc. There particular groups also hove various p-arte ol ihe spec- h ijrn reserved far them, It should be noted that the use of ail bands mentioned so far require a licence. One of the mare remarkable bands lor professional uie in the arte cavoring 0.3 to 3 kHz. This part of the speclium is used primarily far submarine communications. The reason far this \i lhal iIih =e extremely law Frequencies (ELI) arc not heavily often ualed by water. But since (he barcdsvidlh is very smai- if can only be used to tend (morsel data, and not speech Should o situalion arise whore speech communication is vital, 'he submarine will firsl receive a 'surface' command by EIF I- can ir.^n uss the 'normal higher Frequen- cies (usually SW] fur (he iiuh amissions. I/ 3 CDS dtS tsi star:-:-- 27 Urtfily and Sadie Amateur bands (80/ JS0/20/ 1 7/15/1 Orn) 6.765 - 6795 MHz ISM 13.553 - 13 567 MHz 15 m 26 957 - 27.283 MHz ISM 36.P6 - 27.41 MHz CBtEUH 11 mj 27 601 25 - 27.991 25 MHz CB (UK) [1 lm| if vt t M I 50 MHz rad jo cmatcu r (6m) 56 - 72 MHz MOP; VHF-1e!evisian [pheissd out] 76 - 87.5 MHz PMR, MOD 87,5- 106 MHz FM radio 106 117 975 MHz fodiaanvigaSicin fVQftl 1 37 MHz weather Mteffttes (orbiting) 164 - I 66 (1 46) MHz amateur radio (2m) 146 -174 MHz P m 300MHz 174 216 MHz DAB. VHF Band 3 television Incidentally, licensed radio amateurs are aha regarded as profes- sion □ I users Va nous parte oi the spectrum hove been sot osrd^ Fr>f this group of usars, whose transmissions u.\* often of an expenmen lal nolure. ISM bands The ISM bands {Indusfrial, Scientific end M^d^ca f are special in iha- you don't need a titeeme ig i/se them. unlike many oilier bands, [here are many p-erte or the spcmlietfi ihni may be used by anybody far various purposes, on long as type-approved ■equipment is usee. The 433 MHz and 366 MH^ bands are currency l ie bn-st knnwn qI these (cordless phones and microphones), The 2.4 GHz bond also acmes info this cofegcuy which ii where wo lind among alhers r wreless I A Ns and E-luerc-alli Tne microwave oven also has its place hors. 27 MHz The 27 MHz band, also known as CR jCitizens Bond) or \ 1 me Ires, lies between .''7.60 MHz and 27.99 MH/ in the- LfK, and between 26 96 MHz and 27.41 M-Hz in the EU In the UK n license rs required lo useCS, although in many oiher European countries this is no longer iht- case-. I airy drivers and cabbies are one group of people who ore well known lor iherr use ofCB 1o keep rn touch on the- road. This band is also used (os we: 1 ! as parte of the 30, 36 and 40 MHz bonds] fot iqdicK-onlrolled nadc-is such as aeroplanes and remote controlled cars and boats. A sma ! port of tbs CR has been reserved Fai use os on ISM bond. lime signals Up la now we've concentrated mainly on communications between people. There ore also □ score of applications where radio can, municafions are used td automate processes. One example of ibis is the ironsmission of time signals. Extremely accurate time signals are sent from a number of VLF trqnsr mitten, spread around the globe One of the besl known In conti- nental Europe is-lheDCF77 transmitter, which is near Frankfurt in Ger- many. This station operate.-. of a frequency of 77.5 JtH/ and teons- niits a highly accurate lima signal derived from an atomic clock Watches, dock i odi&s and other docks that hove a suitable receiver builr in automatically set their time to ihat horn the DCF77' signal Switching between summertime and wintertime olso happens oute molicdlyl Since those types of transmitter use a (Natively low fre- quency, their signals con be received ol great distances [typically 1000-1500 kmsj. this meant rhal one transmittar covers q very large area. Positioning systems Anolhcr type of an automated Opp lien lion □ I radio waves rt o posi- lioning system. Although GPS is nowadays pssISy much in the pub lie domain, in commercial and military aviation a different type of navigation system is used, which has beacons on she ground, instead of satellites in the sky Small bands have been reserved ihioughout the spectrum far the various types af positioning system. The aviation industry uses several sys'ums side by side In iha IF part of tho spectrum are the sa-co lea NDBs (Nott-bitetfional Bea cons]. These transmil, as tho name implies, a s.gnal in all direc- tions. In aeroplanes, that use NOB navigation, an arrow pamte in the direction of the transmitter. As long as this arrow points directly forwards you know youre Hying slraighi towards the transmitter. Another system is the- VOfi system (VHF Omnidirectional Range). Ihis navigation sysrem tells you at whar compass point the aero plane is relative to the transmitter. Whereas the NDB system only works when you re flying in the general direction ol (he beacon, the VGR system works regardless of ihe direction the aeroplane flies in The IIS (Instrument Landing System) is probably the mas: widely known navigation system in aviation. This system assists pilots dur- ing the landing, so they can still make □ safe andtng when there is bad [or no) visibility, Ihe ILS indicates whether the aeroplane is an ihe right course towards the runway and that it flies at the correct altitude. A lol af effort H put into replacing these: (old-fashioned) systems wilfi GFS basad ones, but al the momenli GP5 is not accurate enough !o use it far loading aeroplanes. Galileo A number at European countries arc collaborating on a prcjecl id create a network similar to GPS. Just like GPS Inis network mob $ if possible to detejmine your position very accurately. This new sys- tem, christened Gal ilea, dsa uses a network of satellites in space 1 1 is anticipated that this system will be even more- accurate I ban ihe current GPS! Throe frequency bands have been reserved for this new system. One is For transmissions from Earlh to the satellites 1o upload new information or course corrections Another is far communications between die satellites ana the lasr ip For sending information lo users in Earth. 28 ilikjfii itelrnnkb - 300 MHz 360*395 MHz TetrafM 1 .2 GHz 1 240- 1 300 MHz radio amateur {23cm | 30GHi 400' 430 MHz Tru mki ng rodi □ \ 650 M H z geostoliofio ry wetrlli er wtel I lie 430-44Q MHz; radio amateur [70cm]; shifp/sHare radar ! 7 10. 1 1 879,9 MHz GSM- 1 800 433 MHz ISM; 5RP , LPD \ 880 - \ 969 . 7 MHz DECT telephone 446 MHz PMR*44& radio \ 899.9- 1 934.9 MHz UMTS 440 - 470 MHz PM R, Tefra 2400 - 2500 MHz I SM {WLAN , Wi f i, Bluetooth] 470 - 806 MHz UHF {DVB-T) television 2446 - 2454 MHZ RFID 876. \ - 958.9 MHz GSM-90CI 2450 MHz microwave ovens 1 030 MHz/1 090 MHz aeronautical transponder (IFF) 10 GHz radio amateurs. The frequencies used For transmissions 1o users on Earth have been made intentionally high [max 5.01 GHz?, since ihese frequencies allow extremely accurate measurements la be mode GSM Mobile telephones are the application ihal has changed everyday life significantly in ih& Inst few years, Mowodoysyou can Find some body phoning ar tenting in almost every place imaginable The tele phone masts of base stations (or the GSM network con also be seen wherever you go. I he firsi GSM networks made use ol ihe GSM-9D0 system. This sys- tem operates os ihe norne implies, at frequencies near 900 MHz. fhis was later joined by the GSM-1 800 network, which operates at Frequencies near I 800 MHz 1 be frequencies tor use by third generation mobiles ware auctioned aff no! long ago, The system used for this UMTS, employs frequencies that are higher still. The disadvantage gf these high frequencies is that the range of the- transmitters is reduced al ihe same power levels. This is nal [ust due to the higher attenuation by ihe air, but ss also caused by other obstacles such as wails, curs and tiees. Any conducting objects {metal or containing woter| cartahule So ihu alJenuation. Thin menus that many more hose stations will be required la cover the same area. And finally,. * I I you want to Find out more about the goings an in the ether you need look no Furih&r lhan ihe Intel net Websites such as the 'Dutch National frequency Register' and ihe pages of the Rodsocommuru cations Agency contain o vast a mount af information about appli cottons allocations and licensing. A search for 'Frequency avoca- tion' on Google returns a I urge number of other interesting sites CWMSl Link* UK SF spfi-r.triJiTi [general] www.CilcDni □ rg. < j 1; /s tn tic/ nr r tv v ~ / m/gutili t n tm n / rn i nit ■ / ra235/ia23 5 _ him {Formed Radiocatnmunicalitini Agency: vavw ofcom . or a . uV /s ro I i u r c ti'-v t? /r o /ou bl ;ca n qn/ra j niq/ rq365 hliTr US frequency allocations; www riTia.doc.aov/QsmhQme/ ollochrt htmf Does a microwave oven cause interference? Fr-om the- FrequEnry nbrl you'll «p ihu! midirtnive ovsfis c per ale in ih: sumo hand &S Wifi (Wireless LAN ] and Sfoeloalh. There me cFIeji tunMitiis arfflmd that miaowing av«n iilerfMe with wireless networks, burl haw line h the in ptertiie? Wireless UIFs use n special rmiidiilcfTon tfithnitpje, whiih niaStes die cl a Fairly wide range gF Iwquende*. This was dene an purpose so that j| Hiert- was mterferntte in o small pert &F the spectrum it would r-r.ly have q small effect on the cwmertion The oluElaqth system, which ts dIsd in the 2.4 Gffi ISM bond., also uses ihi se-colFid 'spree d spHtram' nndu'nl cn Slucteaih irnnsTissfaiss rep dly rhange between 1 f- Ferenl chnnek vrlfin the bond □venting out iKe eFferis of poisiblD interfere me Tbs inlerfETEnce may enginate Fram a murnwrrve Even. This machine is in Foci foil □ pawerfel EraxuniHes in □ hex wflh □ doer. This de-or is there For a very caad rEGsen wftich is la slip the powerful It F energy from esiaping. Mitrowave ivects are sur- ruwufad by iratol and d msrc.1 mesh behind ihe window In ihe tfcm, When tfie door is closed the whole function is o Farmliy tup and radio waves should not be oble 1 q leave the miaawiivs oven In practice ihe 'cage' always leaks slightly and same BF signal will esrajii. This Is usually not a problem, but with older or defective microwave ovens it could be o signifkciil annum af energy If your WLAH receiver dac-sn'l hove a gooif input slags there is q possibikly ihal (lie conneffian sirffcrs wliEn iha mitrmraTC qvm is sumd an. In rnrn cows Sikq this yau'il notice thot iTio date throughput of the wireless nelwaik reducos, I..H rl is extremely irn lively Tel you 1 1 lesa the tonnerticn a'llc-ptherl figure 1. Rf jigrroij. can itcarh beyond the horizon uji.rjg a foyer of ia-nisc’d 1 gases in ihe a.'mo-jyrn efe 773005- sfeklar flahc-.p. 29 Cyril Jouanjan With the aid of a PC and intelligent temperature sensors it is very easy and quick to assemble a professional temperature data-logger. Using e- mail, up to four temperatures can be monitored from a distance. The sensors are simply connected to the PC parallel port. in this article we describe a system that measures and reccuds tempera tmes. The bean oi the system is a Visual Basse program This software reads The temperature sensors, which are? part number DSU 32 I from DaU as Semiconductor. Up to tout sensors can he connected. Toe measurement aecu- rscy t£ 0.5 : C and 1 be interval between successive measurements rs 2 sec ands, ID seconds of 1 minute 7ne program can display the measiLnHi values either as a graph or simply as text, A chan with the most recent cQ measure: ne i its is available and another chart showing rise most recent week. The latter allows zooming into a ieao hit son of one bout. In add i don il, is pos- sible to store the res cits sn separate hies fot latei madipulattan m. for exam- ple. a spreadsheet. A novelty oi this program is the option nr sending etc -mi warning messages via the network to which the 1’C is con- nected- This requires only an SMTP mailserver. The messages contain the dale and time and the recipient can simply view them as any other email. Up to three recipients can be entered. FurthormtHS, it is also possible to check remotely, oi avsn when absent whether a particular alarm lias occurred and at what date and ume. This could i^. u- ed r o muni Lot the tamper aturo of an aif- conditioning system , or for example, die temperature in a computer room oi boiler house. The mazdmuisn period that cas'i lie iecoi ded is one week. Each sensor has two alarms that can be set They arc triggered when a threshold has boon exceeded In this 30 d tkiu tltaiuii - WS PC data logger with email alerting way tine alarm can be raised when- ever, foi exampin, the temperature exceeds 25 and 3D C. For each event u Separate message can be sent An upper- and lower-limit pi two lower- limits are also passible. A hysteresis of 2 G prevents (many) pointless mes- sages when the temperature hovers around the alarm threshold. This car* ouil allows a cheap watu ug system to he fauilt. An ofd PC with a 2U0 MHz Ot so processor and network card is eas- tly sufficient. Figure 3) To ^his Way. conflicts an the I Z C bus are pj evented Tile sensors are identified using a 7-bit. addeeas. three of which arc programmable by the user (typical for an I-C address) plus one mods hit. The address Ires between 144 (A2/A1/A0 alt logic sera) and 15H [A2/A1/A0 all logic one) an stops ol 2 and is programmed Using jumpers. The value (hat has been set needs to be entered Into the Visual Paste program: The- D51G21 is connoctnd to the t 2 C bus through die wires SUA. SCL and GND. Tile power supply is derived from the PC, The 100 -ilF capacitor provides decoupling of ilus power supply voltage. Cansfrucfiojv The circuits ate not very involved and arc easily built on a small piece of pro- totyping board. Ol corrrso, if you are familiar with a PCB layout package Circuits The sensors are connected using the fir miliar 1-C bus [Figure 1) Tiie sensor boards themselves are effectively con- nected in senes, where in each case Lhe output from one sensor in con- nected to the input of dte next one. The last sensor — which rs, of course, the first one if only one sensor is used — is connected to th-o PC. tn Figure 1 tins is indicated with the symbol 7/'- lncirien tally, the- software also supports an internal ISA [ 2 C imerface ■ . r r I Figure 2 shows the sell a mat ii of a amiable interlace for the parallel port of a F'C The do sign has been derived from an application note from Philips and actually consists of only a single 1C. The 74I.KQ5, a hex inverter with open -collector ampuii,. is used as a buffet In addition, a couple of pull-up iMiih-tma ate Jeguited. a 25- way sub-D cop pom or (main) rind mi PJ11 socket. That's ail. Sensor connections The sensor used bore, die DS1521 , already contains practically all die nec- essary components. The 1C also con- tains a built-in thermostat, but that for xkmallty Is not used in this project. The accuracy of tlm DS1531 i:- of the order ol D.o C without the need to: any special calibration. The measuring range spans from -55 C to +125 C and the conversion time is 1 second. As well as rhe 1(1 it self, three addi- tional losiscom an:- required, which arc: necessary for setting the address (refar - I C 4 u lilies tii — I-'C card nmn mas J seasons MfWWf 1 fiiTnr,eir7 PS1EJ1 DS1«1 Z E*C bus |3 *1149] i supply ZVXAZ’ 11 Figure 1- the rensors gre conrrocW wu thu f‘C-hvi. Figure 2. One small tC ana' □ few resistors ma^e o compkie interface. J/ffHlJ - r?rilnr fhrtrews 31 Hi ft> then it L3 also quite easy to insign a PFIP yourself 'ill a final result ss very compact, in the prototype, the pull -down resistors am SMB versions, They ate vety easy to solder directly to the PCS traces, The Sensors are connected to each other using tables fitted with HJ1 1 plugs. The maximum length ot the bus lhat is allowed depondg on tin : lumber of DS 1621 circuits and is determined by the capacitive Load on tho 1-C bus (4-DO pF maximum). In practice, the author, using two sensors, obtained a maximum length of 7 rn If necessary, this length can be increased using bus extenders Like tha 82B715 from Philips. Figure 3. Jumper* se'ecf the addreij, or the sensor Table 1. Addressing Static part Address 2 Address 1 . Address 0 fleod/ Write 1 0 0 1 A2 At AO R/W Bil 7 Bit 6 Bit 5 Bil A Bit 3 Bit 2 Bit l Bit 0 Software Wow let's take a close look at the soft- ware. When you start the program for the very first time it will initialise with the default configuration You can sub fvHguenliy modify the configuration by select my the menu General Configura- tion from the main program window ( F i gum 4 j T] re ct ; r reap ending window will appear ( Figure 5} hi this window, all the parameters related to tbs tem- perature measurements can bn adjusted. At f 2 C Bus you select the typo of PC interface used, The option 12C.ini instructs the program tn obtain the con figuration information (torn an external fits with the name L2C.ini. Tnl s li[e has to be in die Windows folder. In ibis file, under tho section [IRC Card], you can -enter tiie base address (hexa- decimal) ol the I 2 C interface paid (default value is 0x3(10). Under the sec- tion £12C Pruaf there should be the hexadecimal add rose of the parallel port (usually 0x376 far I,PTi j. The parameters for the lour sensors can also be auto red in the screen ol Figure 5. All tho parameters for one sensor are next to each othei Under- neath the decimal address of the sen- sor is a text field Lhat can hold the name of the sensor. For example cool- ing 1, cooimgk. By selecting Yss under Acquisition die eouiijl measuring commences. If sub- sequently Yes under Record in file is selected, the measuring results are saved tn a text file (file_opnLtxt through hi o ppn4.txt) Activating the alarms is done m much the same manner 31 Yes is selected under Alert high, the ahum is raised when the corresponding value is exceeded (otherwise when it drops, below ibis value) You can enter in tho remaining text box the message that needs to he som yin email, Firially, you cao enter at the bottom how oftHti the temperature from the sensors needs in be polled (acquisi tion period). Viewing the results After you have entered the address and name ot the sensor and activated the acquisition, click (IK and you will [M um to the main window (Figure 4) This window is updated at the same rate as ibe acquisition period entered earlier. If toe sensor I ms beers detected the corresponding name is shown on a flashing green background, with the temperature shown on its right li ihs sensor does noi jeply or if tho address entered is not correct, ns name appears with ft solid led background Tn the same manner, the software indi- cut-HS with a green colour whether communication on the l^C-bus is cor- rect (l^C OK), Two graphs show the temperature variauon(s). The first graph contains the most recent GO measurements ver- sus time. This display offers a quick Figure 4 7f:« main program window give# a good overview of the temperature hktory. 32 tkktif Ek’rnaiis - ?/?C05 view nr the moat recent information Typically this is the last hcmi when the measuring interval is ono rmnule The? second graph, using a zoom func- tion - : 'i id horizontal slider, allows all measurements to be examined over the period from 1 hour ago to 7 flays hhd B bouts. Tins enable!; you to view what happened a few days ago The measurements in the graph are updated once a minute independent at Llie selected acquisition period 4farm via e-mail To activate the at aim vle email you require ths Mowing: an SMTP mails ervor accessible via the network to '-■vhieb the measuring PC is connected. If no suitable server is available, but the Internet is, then you can install one yourself. There are numerous free mailsarvers avail able for all the common operating systems. One example is Mercury transport system, which is available for both Microsoft Windows as wo 11 as Novell Netware. - An email account, configured for the name of the temperature station that will be sending the massages. Up to three email accounts to receive the messages. Now go to Mail Para meters to enter all this information (Figure 6}. In Mail server IP address enter Lite address or the SMTP server Tti the boxes for Admhii'.fbniiv, Jfrcomjary and Third email onter the addresses of those who will receive the alarm emails. Don't luiget to tick the corresponding Active box, The email address of the temperature station is regia nod because mail servers usually do hi accept incoming mail Without a sendei's address. Enter iTi-h address r'h h|, you configured earimr. Confirm by clicking OK. After compl&r- ing all this you can send a test mes* sage Eothe server from the menu Pref- Frgure 5, A separate configuration window is used fn set the necessary parameters. * Hml P.H.JHirSlBII ■HE M.tt mva i P *a tt t 13& 121230 Adfmirli rniii tdTlrTLi l+tr&t rvT«Sp f? fleive- iec ;ti>i art wwi uiSf^t»a-¥iaefci p fcsrt Trtrd F Adiv* FC twn>waKifl Dinsl uisilt3uvi*io Figure 6 . There is another window !or configuring ,',h l- e-ruorf functionality. er cnces/lbst. If everything goes weli, thB message will appear sn the mail- boxes of all the recipients Finally Most of the boxes in this program have a brief help text that appeals when hovering the mouse over the approprt ate box. When installing the main pro- yiam, the program ThstftC is also installed m the sflirre time, This utility allows the l 2 C-bus to bo checked for correct operation and can detect the sensors connected to the bus. /LOS i, About the author Cyril Jo van jo n fs 30 years old en has qualiftoalions in inform chion engineering (speciality: system and multimedia-networks] He currenl- ly works in ihe south of France. Cyril Kos been a licensed radio amo leur |FbNYVj since 1900 and os o consequence of ihis, hobby he has been engrossed in the various techniques ihol ore required for ihe realisation of certain subjects, such as mechanics and electronics 33 ?/?U05 - (Ifbsf Etelnsnin A robot with servo-powered legs Making a robot walk instead of drive around on wheels can be a daunting task. The author of this Walking Bug came up with a remarkably simple solution. A Vreugdenhil 34 t ! skloT dmiMio Z/lCfti Alt! lough our robot does not stand upright on two legs, it can actually walk usicg jLLSt two servos arid a msm irmiru amount of electronics, The poww of the design is. of course, found in ihe combination oi these two ele- ments, The servos make the ' natural' movement needed here: yust back and forth. As an advantage ovei other actu at cus. they can be directly driven by a lnicrocontioUnr,. which save s ns a lot oi driver and interfacing electronics. see Figure 1 The mechanics] const) notion of the Walking Hug is also relatively simple, the Negri being sec tired directly 10 the servo spindles. Servos A servo is basically an electric motor with a goat assembly driven via an internal positional detection dmnit. Besides the supply voh ago, the servo needs a drive signal that servos to indicate the desired poattiou. Conse- quently the servo monitors, changes and maintains its spindles position, all by itself. As Jong ns the drive sig- nal remains the same, the servo spindle will not turn — the spindle will only turn if the drive signal changes. The drrve signal consists of square wav e pulses with a swing o [ 5 volts. The period of the pulses is constant, while thoir width \ determines the spindle pasi ■ lion. The zero position of the W set vo spindle corresponds to ™ a pulse width of about 1,5 ms. Depending on the desired amount of rotation, the pulses are made shorter or longer, however a constant period of 20 ms has to he maintained. Software Our purpose is to make the robot put one leg in front of the other so as to make the creature ‘walk’. Considering how a servo needs to be driven, imple- menting this movement may look like a complex rank for a microcontroller to hart die. Fortunately, it could he done without too many problems thanks to the programming language used by the author. HABCOM-AVR comprises a special routine for driving servos. It accepts a value, supplied in die form oi 3 parir-ineiei, winch directly cleurs mines the spindle position. Tins routine relieves us of the task of having to cie- Fiyure i 1 Tfie microprocessor exercises rived centre i aver t he servos. ate the FWM pulse shape and timing required for sqivq driving All we need to do is program tho actual ■walking' of the robot creature This l ias bean achieved as follows m t he p i ogi arn Ei i tii e m ss n I oo p. su br o u- tme 'Step V is jumped to every IDO ms In this routine, the Etncto counts from 1 to ^2. the values corre- spoitding tit the \2 posknms a servo spindle runts to when one Teal' sfep is made, H is d where- to the program ynuTl find a table allowing tho micro to look up a value to be read and copied to the servo subroutine at the current suite of tho stop. That concludes the- operation ol one- servo However, the other servo needs tu work ‘in step' to enable the creature to actually move forwards (and back- wards). A co ordmared walking move- ment has been achieved by making one letj precede the other by an angle of between 45 and ED degrees. In the software, this has boon implemented by adding a fixed amount to a current ci&rvo position, and reading the value for the resuH in the lookup table. In this way. the s*j vos follow aach other's movement by a fixed difference. Backwards You may have seen on the photographs that our Walking hug has two 'ant on tsae'. Two stiff wires are secured to micros witch fevers, allowing the micro- controller to detect if the Bug has run. into an obstacle. If Lhat is ihe caae, the program branches om of ihe ruarn loop into a subroutine 'Back' causing the robot io walk backwards lot a while . The 'Back' subroutine simply calls ‘StepT but tins time with the variable 'Sense' set With the 'Sense' flag set, the 12-positmr: counter counts down causing the robot to walk backward s. Trie actual direc- tion is determined by the micioswitch that was first closed by the obstacle At the start at the main loop, before ihe jump to ‘Back', the variable Direction' is set; 1 Team tig la ihe left and 'I. to the right. Sing this variable an. e*ite difference is created between the servo positions. Hardware An you may have guessed from the soft ware description, lire hardware is 'modest' by all standards. An Attnel microcontroller type AT93S2313 fe tin- brninri of the little robot directly con- trolling the servo via port pins PDG and PD6. PD1 and PD5 drive two LEDs that light alternately when the robot is walking straight on. or indi- cate it is walking backwards to the Taft' oi ‘right' St and 52 are i rieros witches secured to the two antennae — when actuated, the- micro knows that an obstacle is in the way. The bug is powered by four batteries ci rechargeable cells — voltage stabil- isation is nor required. Construction On the printed circuit hoard designed for the Walking Hug (Figure 2 1 you first mount the passive parts, that is. the resistors, capacitors, ceramic res Vfflh A-hErr'ulnr-o 35 COMPONENTS LIST Resistors; ki = mu R2,R3 ■ ISsT 15 Capocitori: a ( Oi€4= IDQnF C2 = lOliF 1AV radial Semiconductors: D l , D2 - LED, low-current, 3mm IC1 = AT90S23L3-10PI ijitriiur. connectors and micros witches. Next, continue by fitting ihr: LEDs and the microcontroller (preferably in an IC socket). We recommend first checking the electronics Eos propet operation, Tills is s Imply done by connecting up the battery and the sofvqs. if the servo discs move up and down and the movement changes when the micros witches are actuated you can safely assume that the circuitry works as n should, and you are ready to assemble the Walk tag Hug, The backbone of the creature is formed hy a sLnp of metal bent as illustrated Miscellaneous: XI = 4MHz ceramic mionaiat K2 - Sway 31 1 pm header K3.JC4 - 3-woy5IL pinhEcdsr 5 1 , S3 = miniature micro 5 witch. (e.g., MBFdB, Conrad Electronics # 704571] 2 servos 2 ha tier y holder* lor 2 AAA botteriBs PCB raF. 040071-1 Irgm www. rh G-pcbs liop .co m Disc, source ft. hi>* wire in plane, At some distance from the servo, again bend the two ends away from Eho servo fit an angle of about 90 degrees. 'iTiL? correct position of the disc (with the tegs secured or; it] to the servo spindle may have to be astabhshed by trial and error. The servos and battery holder may be secured using tie wraps, although this i rates exchanging the batteries a bit bifficul i AEte m at i vel y, glue the b a tie ry holders eg the servos. A less perma- nent option is to use rubber hands nr Velcro, Ybtir 0wn experiments This design is ideally suited to further experimental] on, nor just with the mechanical construction, but also with dll parameters used m the software control. For example, if you decide to use different legs and adapt die values in the tables, or the difference values, the Walking Bug will continue to work, .-ir la fist in principle, sometimes bettor, sometimes with a funny gait! Your aim should be to hud the beat interaction between software and hardware. The PCB contains an I3F (in-system programming) connector. K 2, which allows you eo Toprogram your robot using BASCOM-AVK (see link at the Mini of this article). The wiring oi the ISP cable (including three resistom) is summarised in Table 1 In BASCOM AVR, select sample electronics pro- grammer' Web link BA SC C )M- AVfi www.mciglBC.coFn Table 1 . Programming cable dofails printer part K2 function 2 (vm 330 flj 4 MOSI 4 (via 330 O) 1 (Gsd 5 (via 330 fl| 3 SO( U 2 M1SO IB 5 GND | \ Figure 3. Showing how fne various para ere secured la ihe meicri backh Ofle Figure? The brains' fh& Waiting Bug. 36 ihllar Ekrliofii,- J/MS FREE Layout Software EASY To Use] Very LOW Cost! Extremely FAST Turnaround! software free- our ESIGN boards four- layer two your >JD design with jt quality boards dick just us your a ECEIVE days top just Ml express pcb.com ’ :iA,ircl ; 3?.n" PS^UMltl h=^=;ureE ‘ S‘Jr’-gra ],■ OS 1M 1 1 Dual Oiannutl OsdHdEi-iope, Signal C*n«rBtpr a Hull! Function Instrument £149 shipping Hi VAT £125 + shipping a vat TBthn-mi [nfiintiiiuiirL S-iles Information *T 3 — - * eimr: lit l*^V r i 1 1 1 ' F 'SIlntTAv' DSlHli Fcjtn-.'. UuU ■a jLM .1 w I ! 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This article describes a sensitive detector that will equally faithfully produce a sound in response to pulses picked up from an 13.56 MHz RFID tag transmitter, be it large or small, 'portal' or 'portable'. 3S t !e kt-jE dtoroun - 3/ ?u05 ra hcjure i 1 At fhe Jif?orf c/ tfrf? circujf we *ee fiiE NFd 15 monoiiffa'c necBiver/defEcfor It The systEin of passive RFID rocognt lion has bean in use for decades already mainly In large department and fashion stores like C&A Tfadition- ahy, those systems work at frequen- cies designated tor lSivl (industrial scientific, medical) use Many efrtforeni: frequencies have been adopted since the early I§B0's. The system is extremely simple and frets proved quite effective in slopping shoplifters- All clothes and other items (or sale in the shop are 'tagged" with a difficult to remove, mass produced hence- Sow cost plastic ‘disc' contain- ing no moie than a resonant circuit tuned 10 any one of many available FAS frequencies. These are generally in the bands i .36-2. 8 MHz, 7.44- 3*70 MHz, 7.10 B.VO MHz but many other frequencies may be us Ed depending on application, permission and country, Once your purchases have been paid for, checkout staff will remove the tag(sf Wo thing will ban- pei if you l lieu cany yout shopping hag through an RFID checkout gate The ARS or glass gate contains a large antenna coupled to a quite powerful pulse transmitter working at an HAS frequency. If the passive tag is still present in your bag, u will resonate in response to the transmitters pulse and drew a tiny amount of energy from it. the coupling being mostly through Lhe magnetic |H) rarbei than the electrical component iE). The pulse ringing, resonance, energy with- drawal or indeed any other distur- bance of die magnetic field created by rhfs TX powHT is Faithfully detected and on alarm is sounded. Time to open your bag at the request of 'Security' or the shop manager. 1/3305 ikber ^irttnia 39 Figure 3 I he FCB is single- sided JW also curries component at the: soWer *rtfe, in firis case a couple of 100-nF SAID capacitors for etfeciivo supply decoupling COMPONENTS LIST Resistors: It I - iota R2 = 8kD2 R3 - 2kll2 RJ = 470T1 R 5 = lkll 5 TSUI J?7 = 4 L7 aa - loofcii R9 = 5604 1 FI IQDkil press! Capacitors: Cl • determine expsrrmeninlly; dorr WltllD if it C2 - 470 P F G3, C7-C10 = lOOnF $MD tax 0805 C4 < 22yP 16V radio! C5 - 39pF Cb -• 56pF CM 470nf Cl 2 = IfiF IdV redid CT3 = 47nF CUn 2pF? ■ 6V radial Semiconductors: 01 - LED, gie-nn,. low rurn-jnl [)2 = LED red. low current 1 1 ~ BC54.7B T2J3J4 = EC557B 1C1 NE6 ! 5N or 5A6 1 5N (DIP2Q cost?) iC2 ■ 1/295 1CN iDlFE case) XI = BMJIzqudrli crystal BZ1 = 6V DC (active) buzzer Miscellaneous: FI I.FI2 - SFF5 5 IF Ceramic Fii~r 51 = On/oM iwlkh I contact" ofiijFnaiJvely a pushbutton Casa- Hammond I59QS diet a Si 9V bal-ery 'A-ilb rljp-tvn loads PCE. reF. 040299-1 From The PCSShap From flaky to tellable Tri the uaily days di passive RFID. Lite checkout gate* and ansDciareri hard- ware produced mote fake than real alarms, to iha extern of staff often no longer bothering about coiilmimuE afflatus Those wore also the days when you could walk through an RFID gato with a common- oi garden grid dipper uj you f nock* 1 : Tuned to ail EAS frequency and trigger mayhem in the Seoul ity department, in follow-up sys- tem a great improvements were achieved in respect of reliability by miniaturising and hiding RFID tags in and on clothes and books. Instead of snowing the lag. it was "disabled’ (we’d say grossly detuned) by a strong magnetic pulse at the checkout. Today, muchol the world's fashion and clothes retail trade seems to bo 'tagged' invisibly and transmitters have become unobtrusive to the extent of being handheld, much siktfi a metal del actor for use on poisons. Tho basic; principle. however. remains tin changed a passive tag will either detune or load’ a nearby RFID bans nnttex Passive 1ft’ IDs cannot convey data unless lhat’s taken to moan "I'm here". Also, goods (and even Livcstcxzk) jdsritj'/j'canon using unique numbers is securely m the realms of active RFID ci barcode systems, never passive RFID. The E5M Frequency 13. ob MHz on which opr receive i ts designed eo work seems to bo m use For active as well as passive (EAS) RFIDs. A dedicated receiver The detuning and resonance effects mentioned above take place at rela- tively smalt distances from the trans- mit tax, say, two : relies oc less depend- ing on TX power and amentias used. Tu be dbie to spot an active 13.56-MHz RFID transmitter from a greater dis- tance wr obviously need a sensitive rec Diver and a pickup antenna that's as small as possible, Hi- re. h supei- heieiodyne receiver is used in combi- nation with an etched micros.) rip antenna Oux design is not suitable! for 134 -kHz RFID systems. The circuit diagram in Figure 1 is hap- pily uncluttered and docs not contain a micTOCQb trailer oi any other black- box element, Tim central part is an NEFlb (or 8A615) integrated circuit, IC1 Refeinng to the hlock diagram oi the 1C oi Figure 2 we'll explain the operation of the receive: For conven- ience, the pinout of the 20-pin DTP ver- 40 alitor dbdronks V2MS figure 4. Some components need to be fitted at /.he solder sida of the board too figure 5. Top side of il\& Snoot d With ail tin! ports fitted J'Vn.'t' the- wire fmA eonpec/rgg tfte striptine antenna to C2//C1 . = ioii of th e 1C ]3 also shown. Tin - SAG 15, says Philips, is a high per- formance monoUthiL: low-power KM IF system incorporating a mixer/osciLla- lor, iwa limiting intermediate fre- quency amplifiers, a quadrature detec- tor, uniting, logarithmic received signal strength indicator (RSSt) and volt a ye regulator. Ir the type code sounds vaguely familial we bet that's due to the ’B15 combining the functions of the famous JTE/SAB02/61X double-h al anced mixor and the NE/SAH04 demodulator chip. As compared with tile NE/SA605 the WE/S AS 15 features,, among othei plus points, a higher mijcor input intercept point and higher IF bandwidth (25 MHz). The NE/SAGGG and WE/SAG 15 are func tionaliy identical but the ‘615 has improved specifications in some respects (bps SAG 15 datasheet). The RFID transmitter signal is picked Up by a closed loop antenna marie from PCE tracks. Together with tuning capacitors CJl and 02 we’re looking at a miniature magnetic loop antenna. The balanced antenna signet is applied straight away to the mixer inside the WE/ S AS 15 The oscillator input of the mixer (roll i to Figure 2) receives an 8- MHz signet obtained from on art 2 crystal XL Tire difference frequency obtained from the mixei is 18.55-5 = 5.56 MTfa, which is taken through a 5.5 MHz ceramic filter (nor- mally used lor TV sound snbe airier systems). The filters bandwidth of about 300 kHz is sufficient to receive signals between about 13 550 MH* and 18.650 MHz, which nicely covers ollr target frequency of 13.560 MHz Tito output signal of the IF amplifier inside the NF/5A615 {pin 16) in applied to another 5.5 MHz ceramic filter, Fl.2, fuT additional suppression □! unwanted uiixei products The li mi ter inside the SA/NE615 (input: pin K) also amplifies the IF si qua). Referring back to Fig- ure 2, both filtered amplifier signals am applied to the ItSSI circuit which serves to tell us the signal strength of the RI-ID transmitter. TheRSSt output (pin 7} supplies a cm rent between 0 and 80 pA as a meas- ure of the received signal strength. The relationship is logarithmic allowing largo signals to be measured too. This allows as to crimp our detector with two activity outputs: a LED, D1 and a buzzer for far away and nearby KITD transmitters respectively. The demodulate] m the NF/5A615 is simply not required so we need nut waste any words or even external parts on it The detector's trigger level can be set to personal requirements using preset E 1 1 Lo practice, jt should bia set to max- imum scncitivily, Le., the LED should just not come on when you're sure then? isn't an active RFTD TO for miles at mind. None the less, powerful 5W stations or man-made noise around 13.5 MHz may cause the LED to light occasionally The adjustable threshold also allows a lower battery voltage [aftei several hows of use) to be compensated. The receiver has a simple power sup- ply consisting mainly of a low -drop regulator LP29G1 whose low-ball eiv indicator signal is used to light an LED when tho battery voltage drops below about 6 V, The current consumption of the receiver m standby (non-act wateri) state is about 8 mA from the 9- volt RP3 battery. Co n s f ruction The recfdvi-: is built uit the piuiietl cir- cuit board shown in Figure 3, The board is single-sided and no problems aie expected in the construction depart men L as only regular-size coirs - ponenrs are us&.ci at the *top' side and a few SMD raps at tho solder side. Also, there are no induct dis to wind! Tire SLID capacitors at the soldei side of the board have to be fitted first The positive aspect of iheit small size is their ext remety effective decoupling abilities while also allowing the hoard ssze to be kepi, to a minimum. The SMDs may be seen in the photo of the solder sided thr- board. Figure 4. The top side of the hoaid with ail the com percents fitted appears in Figure 5. Quite satisfied with the results obtained we plan to apply 'SMD caps I/lfKU - i([t!;ir iitcfro-.iu 41 Male The RMD receiver described in this arti- cle n intended For educational & ^eten- s die use only, !r w»H sound an alarm if a nearby, active 1 3 56-MHz rransmttrer i > dtiledeJ, which may indicate the pres- onet! of □ (hidden) RHD lag of Iff active ai passive type Figure 6 A ioak inside our tested prototype of the RFID detector. for decoupling ni the solder side' more often in lutuie Efektor projects, so st may he gaod idea La buy a small stock of0S06-size TOD iif-' oapaesiucs. If you object to the? use of SMDb altogether than solder on a couple of miihatufe ceramic C's instead The NIv'SAfilB is best soldered onto the- board rather than inserted in a socket. The quartz crystal is preferably - lav, '-profile type. T be photographs underline our strong advice to fit the receiver in a metal case, with the loop antenna of course protruding from a slot. A type 1590 ilk cast Case from Hammond will also allow the battery to be secured inter- nally with Veil to. Plenty of too tv. too, for the omaff switch nr pushbutton. Test, use, customization fi mg a dip meter we worn uh!e tg nake thn LED light aL several metres distance front the itetwtor The buzzer started to sound when we approached the detector to about 1U ems RFID uansrtiiliers with gate typo antennas can be mlied upon to supply much si rougej signals so you should be able lo detect their presence and activity hoar:, quitr^ a distance a nice highs treat pastime while tire missus does the shopping The values of R2 and R3 are subject to experiment at ton if you want different LED/ buzzer activation thresholds The antenna may be carefully toned to resonance hi s 3.-56 MHz by tweaking the capacitance across it (G1//C2), Tens is conveniently done with the aid of a gtid dipper or a square wave generator and monitoring Lhe voltage developed across PI (H5SI output! If your func- tion goner at or does not reach up to 13 6 MHz thou tot it to a frequency of which 1 15fi MHz is an odd harmonic (like 3,712 MHz or 4.52 MHz). Termi- nate the generator output with us nominal impedance in senes with a few turns of stiff insulated wire formers into a small loop. Hold this loop cIdse to civ rl&toctet's antenna and increase the generator output levs! until an ES5T indication jh oh rained. How work op ihv capacitorfs) .uiliI the received IevoI maximises. Finally, advanced user* may want to try out a larger surface antenna to gst even higher sensitivity. A window antenna with a size of 75 - 75 mm tuned with a capacitance of about 5U0 pf is a good starting point. A much simpler variant, two telescopic or whip aerials oi about 1 motro in length may also give surprising results. Rod i variants are, of course, Jess suitable Jut cove it ope rat .on. nvesTOLi The road not taken Sonne cf you moy wonder why lhe raceiver u not designed using a slunfdord interrue- rfinte frequency oF 455 kHz or 10.7 MHz. After oil, the NE/SA61 5 con hnndfe bath and u wide choice of filters h available for flteie industry qun dot d IF frequencies It sure is possible Id build o singfe conversion receiver for s 3 56 MHz using the NE/SA615 and 455 kHz or ]Q 7 MH;e lh lei's assume we wish to use on IF of -! 55 KHz for which many did diuup ceramic f^rers ore ovailabfe Consequently, 'he local oscillator (LO) frequency would hova tu Uj I 3 .5-6 MH;- ■*■ 0.455 MHz = I 4 015 Hz or 13 1 05 Mb z B-olh are perfecliy possible |F you ura willing 7o Fork out 1 5 20 pounds Far □ cesium -made quartz crystal; and suFfer a supply lime oF 4-6 weeks. Fhe some horrors apply if an IF ol 10,7 MHz <5 chosen; 'impossible' LO frequencies like 24.26 MHz or 2. -66 MHz emerge From the calculations. ihe alremaJivF- presenlsd here □ cheap -0 MHz (niicroconkollur| crystal and two equally low cost t-Efamic iillers Reals any a Hem pi a! using non-standard quartz crystals for a DlY prated 42 ffailix fkrtranis ■ l/2t3i For rapid development of electronic systems. e BLOCKS b^b emsp cuMt tioojis ow±i of wfititi mtiifig B b tot* tf itlndraniGS typitalty m An ayUam E-btot*a OJn t» jn^AAanod ta C, Aiaamftiy a, id a-u bghliy liiisgAJtEd *wlM riowcocu ■ wlseh inslafiBy canv&rj Co*' chads nto FIGmicra Lucii NEW LtiVf cost USB PJC „J 3 lus a wide rsr*[jB Of fltogi Enef&dibty a^y ..equals ejitrarrMaiy tajbd iyiliim prog^rnmefs add-on boards and to use software baaed or development Bo !Ne mobile text mssseginij (Ew^*if37. inuM acsesacrrias... flowcharts... E-blocks. idlkjwfii IEfi) ...and solutions for learning and development... 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(tonliii? .- ^:i5D-:-:v f-iL-A ri IVlR'lll . i iv o -r □?!;<»► Hi WliRL E-K-Z fl-JS 4-1A i IJUUTlUL lSI-F G-W,- 51* j Hn, c-n fur Ifi^H ju , ie !c brfcd-i F ra.-EiLi77.rT } I H t S-.TtF.'A t Dairen iflPPr 4 Ugh Ehali^ 6 : Cr,1 n trj?: ■ ) i:*RF.iN5 ■ w 13 tl6 Villa Ik ddal k VJJi r. r Gc->i: e 4 C=n=£? Special Offers Spectrum Analysers OSCILLOSCOPES likj-inl ir^\t *UCl !VrLT| ttlK rtHiii 14 m SfijLli-UnA- - uta at; Ca.-= 411 MCJU Kfl - ^JJ 'll V; -rfr yJln-A— VFu tLf.aaaii fymfiMtaQmXWto' EISA r»:a PJF£SI1 tVX / f Ilia H P l14Pft lrfM>mv L-ryw ti«s if. 4J.TU. IT* (Mu nilrlWi: rj rs-s ti.f. A b - l.-.- ’am TltH AT f HIM ! .« ■■■ -m-t ■ pu,i,- fuse huc»b;uiIv n#w BJ. m Fra? tmam »£Wf . . mzi •m p ,E - . . £ t j > n#H Mi turn £M 6 L&ii Uo - 2&ir 17 W Rnttia C(HTsniuJ[tcallnti£ leil Sell | HJJCT4* : ; - trdst tan i uuB cic u F-uiirn*. r'TJB U> H3I1F3 33 E I Lni 2/3605 tk'iimt 49 Digital terrestrial television (DVB-T) is now available in many parts of the country. Of course, you need a DVB-T receiver and a (new) UHF TV antenna. If you don't have a suitable antenna, the small indoor DIY alternative described here is a simple and economical solution. SO slektw rl^trtiRiis J/2MS Simple and economical DIY indoor antennas Terrestrial digital video broaden. i jpg is now available in many parts of the cou Fitly, and there are plans to oventu- ally switch off existing PAL analogue broadcasts aUogethet: in some parts of Europe this is already happening, if you amenity receive television by sate Hite oi cable and, for reasons of cost wish to switch over to DVTi-T, b DVB-compatibJe antenna is required. Of course, lias is not connected direct Jy to the television, but rather via rr LWE T receiver, or no -cal I fid ‘set- top box". Only s few of the OVB-T Deceivers have a simple itidooi antenna available as an accessory. Figure 1 shows an example of a baste rod antenna. Tim main disadvantages of this type or antenna are its soma times unsightly appearance and its narrow-band sen- sitivity compared to the width of the UHF hand over which lire digital chan- nels are spread More appropriate for indoor DVB-Tubb jp the patch h menu a known as a x hul- icrfly dipole' after its striking shape As well as demons tratinq a better broad-hand performance in field trials this comparatively discreet antenna can easily be hidden, fern example behind a modestly -sized picture frame DVB- T Thanks to the data compression offered by MFE.G-2 it is possible ].n transmit four digital channels in the same bandwidth as chat occupied by a single analogue channel. Thrs is partic ularly impressive when you tonsiclei that a modern television signal with G25 lines and a btl Hu field frequency would give a raw digitised data rate oi around 216 Mbit/s. TJie bandwidth required for that would bo prohibitive far lerrestnai or satellite transmissions MPEG - 2 is a significant advance on the MPEG- 3 video compression stun hard It can reduce die digital data rate to 13,27 Mbir/E. just 6 oi its erfgina! vulue Also, a sophisticated madula- tion scheme, known as CGFDM (Coded Orthogonal Frequency Division Multiplex), ensures tiist the available bandwidth and transmit power are used optimally. Very early article on DVB-T may ho found in [1J. Butterfly dipale Tin? icai antenna impedance at a bin- ieifly dipoie is uE lKe same or-dor oi magnitude as that of a hill-wave dipole. For such ,-j full-wave dipole sys- tem o typical imped anen would ho between 240 , : .i and 300 f i, and inprac rice probably nearer 300 U than 240 0. In any case, matching is required to the nominal 7b Q input jinpetlance of thE antenna input of the receiver. I’o i m matching Transformer, used as shown m Figure 2, with a transmission ratio of N, wo have. N ~ {zj/zj 1/2 - n/n 0 vjhetn ^ uml x c are tespectively the input and output impedanu-H:-, or tln- system mad n, mad n., are the numbers of turns on each side at the trails- formes For a transmission ratio N — 2 with n - b] +n 2 and n D - rr 3 we find that the numbeis of turns n r . n - and n i are ail equal. This makes the practical construction of this transformer consid- er ably simpler: l^ecause the same volt- age appear.-:, across all the windings and because we dn not ne> cl die gal- vanic isolation between Input and out- put that a full transformer would char, we esn use a single coil with a centre tap as shown in Figure 3 Ccmmoniial low-loss mr-comd versions of this transformer have a biiilax con s: i 1 1 mot ■ Figure 4 shows the arrange- ment, where eight turns of two par al- ia! O.u mm diameter enamelled cop]wr wires (here shown in black and white toj clarity) are wound on a 4 -mm diam Figure I A simple indoor DVB-J ontenna by Tech ru Sul, 31 an long, flOu.'Ca: 0 lylbor }, Figure 2. Tbs Irons To rroer mofebes rbc- antenna to □ 75 i t impedance. eiei cylindrical former, resulting in negligible coupl i:ig fosses. Winding 3- 4 of the air-cored pans former ends up being slightly larger than the other: Lins results tn belter matching ia the actual antenna impedance encoun- tered in practice. As the circLSLt diagram of Figure 5 51 2/iOiti aldtn tffdumks Figure 3 Alaielifng os mg a fraoi former wih h a single winding. shows, a ceramic coupling capacitor Cl is filled This ensures that any DC level on the amentia input of the DVB T leceivei is not shorted to ground G an orally, receivers provides 5-V sup- ply for an optional active antenna ot for a sepmate antenna aniplifrap Construction Tiie whole butterfly dipolo antenna assembly, including transformer and coupling capacitor, is only the thick - Figure d. Practical construction ujing « bffitar air-totr*} coil ness of a ballpoint pen. it can be con strutted on a single- sided piece of 1-5 mm thick epoxy resin primed cir- cuit board. The mounting plan is shown in Figure 6, and the layout, as always, is available for free down loading from www.elektor-etectron- ics,co.uk It would also be posstbie to construct die unit using thin sheets of zinc, cop- per tn brass on an insulating substrate made of wood or Pa .apex Figure 7 shows an oxauupln constructed on a Figure ;.i. Antenna wi'Jfi transformer and coupling capacitor. thin curved piece ui wood The In.uis- former and coupling capacitor are mounted on the hack, along with the connections for the 7S il coble to the antenna connector. Television transmitter antennas may be vertically or horizontally polarised, hence the dipole must bo oriented accordingly. As always with indoor antennas, especially in the DHF range, some experimentation will be required to End the optimal position to minimise the effect of reflections. In general, Figure- 6 Component *irfn of the printed circuit board [reduced) Copper uack layout r.vt.nhhlr- hr download hom oor website. 52 eltlkr fWtrwiki ■ 3/70O5 however the ant anna cannot make up fur pout reception* for ejtajiiple on L ho ground floor of a building. Use of an antenna amplifier seem is not tq ho recommended Reports- on Inter- net forums suggest that signals from other frequency bands of the electro- magnetic specmmi, which may also be picked up and amplified by an active antenna, can cause problems. If bolsc spikes exceed the (rather low) Input i hits hold level ol the DVE-T receiver, then even the complex demodulation p recessing in the- receiver will nor be able to prevent distortion to picture or sound Tins can also occur when an antenna amplifier is overdriven in an area of high signal strength. Since the butterfly antenna described here includes a 75 £2 transformer, any ordinary cheap commercially’ a variable antenna booster can be used if signal amplification is really required, for example, if the sei-tup box or receive! iF, located at * relatively long distance from the antenna. 1 1 J Digital Television, Elector Elwtrenfcs* September 19^5. For ibeor-ehonl foundations and □ good source of references. Kraus, John D. Antennas McG-imv Hill Book Company, l9iQ. Figure The author's prototype antenna Comparison of indoor antennas Of course, rnony manufaclurors of television accessories have turned ihgir attention to ihe OVB-T market p€>r example, Hama make an indoor antenna called ihe 'B uMorfl y 1 whose geometry is rather similar to that of the butterfly dipole. The proportions | Figure S] art suggestive of the cross-section of □ breamed antenna [2], The patch design by Harna, on the other hand, is reminiscent of a strip dipole. Given its physical length of about 40 cm, it will have a resonance, and therefore be mast sensitive, at around I MH/. This lies in neither the VHF the UHF band, bul between ihe Combined VHF and UHF indoor antennas are generally something of a compromise. Nevertheless, Thomson has chosen a different, but no less interesting, variation; the AN7D2GQ (Figure 9\ is a hvo-bond antenna whose smoll internal dimensions are clearly designed for ihe middle of she UHF bond, although too small for the VHF band, the circuitry is designed to compensate by electrically lengthening the dipole by a set amount The geo- metrical dimensions of the dipole ore more favourable for UHF DVB-1 recep- tion: overall, a sensible approach. This principle also applies to ihe but- terfly ante r; L'^>y titti :■ ma 1 % ± j pnixihla area T/NS- rj dc-ne ike =a:-i-szt ,’h S/J\D{h) CCnJCCJrtoflfa Part 1 : PCB design basics Karel Wakavcn What do most electronics engineers enjoy a lot? Designing printed circuit boards, of course! In an irregular series of articles we would like to familiarise you with this subject. We start as simple os possible and it will become more difficult os we progress. Feedback and requests to caver certain topics ore encouraged and welcomed! When you're jjusr designing a small PCB, it often is not (tier important where the actual components ore placed. However, there ore q few rules gf thumb that, when fol- lowed, quickly and easily result in a much batter PCB, Berter in this contest moons lower rsoise in she desired autpuP signal and tens interfer- ence with other equipment. The Iasi sentence means, translated into practice "your amplifier provides o better sound, makes no additional noises when the Fridge turns an and does not inierFere with your mobile phone". The following statement 15 per haps surprising, but is, actually true- "'The optimum position of a component on a PCB is for nearly I 00% determined by ils function in the schematic dia gram That means you can not avoid thinking about the Func- tion oF each and every compa neat in line circuit. Example We use an amplifier stage os an example. What ore she diF- t ere nr functionalities that can be distinguished? Ln Figure 1 , C5 b 0 decou- pling capacitor which decou- ples the power supply voltage The current drown by 1C I will change during operation arid C5 ensures tlibt the peak current demand can be delivered. Cl is □ du coupling capacitor Os well, but in this cose it serves the purpose of prevent- ing any burn and interference From the power supply From reaching the signal C3 i:. o decoupling capacitor loo, but this lime nor for the power supply voltage, but lor 1 he signal instead Its function it to ensure that the inverting input of 1C 1 is connected to ground, via R4, for AC voFi ages ? Decoupling' compo- nent must £i£ placed as dose os ti pi veti coble to the nodes I'hat neeo to be decoupled. Long traces havg a higher impedance \- resistance Ioj high frequencies) and os 0 consequence llru decoupling w i I! not woi k as well , The higher th~ Frequency, the mare important i! becomes fa k^ep the traces short. Pay dose elite nlionf To clarify this □ littlo more, lake a look at Fig- ure 2a The traces towards and away always form a bop (also when one side or ihe component is connected to ground) In the Figure we have shaded i he area beiweon the I races far clarify Wc cannot overemphasise thol ii is very important Id place the tract s, in such a way I hat the shaded area ^ as small as is possible, tr you hove to choose between long tracks with o smaller enclosed area or shorter trace : with larger enclosed area, I hen choose the .ay out with (Fie smoFlest area* Why ihol is so we will ek plain at a later time. II is 0 little too advanced Far the present discussion. Cl 2 and C 4 are capacitors in the signal parh, En tills case it is also irue that shorl traces nnd smell area provide losii apporjunity 10 pick up trouble or cause Irauble. Wg repeal the above a nee 11 tare because it Is very mipa/tanf that you think about this Haw does a signal connection hove on are In Ftgure 3 yau con ree that the signal does not only go towards the capacitor, but also has c return path via ground* I he ground trace has a certain FenglF* as well! Signal path and ground 54 dfkte pbrtrpnia JyJCdS Ftt □ a* ii * o C3 o m'BJB ;;*> C ft ' C1 I “ - r !, l C2 li ! °< C5 O Ri O R2 > CA O Figvrs 3 The area of rfur iu'gnuJ fcnnECitibn is formed by ihe signal ptirn »j».-.nndFs flnrf fjwrry from fhe O.JfFpcviEn.f, path together form a loop! i his should not come? aj a surpiistJ to you Your very firs! acquain- tance wiJn electronics probably involved a smell lamp and o butteiy And when did the lamp light up£ Jus! when the loop is closed... So, pay close □HefUiOfi in Rule 1 1 We con : 'icsko o few addi- tional comments wilh Fegcirds fo the signal path. The older youths cim.org us, those who grew up wilh record players and valves, will remember how cosy it was to test or amplifier from days gone by. A finger in the vicinity of ihe input was enough Eo generate a foud hym horn the speaker. T h i l worked so well because the input lo a valve amplifier is high impedance. High impedance connections pick up interference much easier. Always Ir y to make on esti- mate of hov^ high the imped artcr? of a node is ond poy attention to make sure rhot ihe connection is as shcrl as possible and if possible run n parallel Imee connected to ground os a shield \= keep mg ih£> arou srnoff*] Rule 2 is therizfara: K&Gp i i tg 1 3 -rmipedon ce eo n neefron i shorter fbon tow-impedance ones. Rd ensures thoi ihe aulput of the circuit >n the idle stare is exactly zero. This prevents spu- rious noises From ihe loud- speaker when the amplifier is switched on 01 of! R i and ?.? provide For *he cor- rect DC bias of the non invert mg input of the opamp This node is decoupled with capac- itor C and is therefore not that critical. After oil, the capacitor creates a low-imped once con- nection For »nlerFerence sig nals, making ihe entire nek- WOik less sensitive The rests- Igfs moy be placed a little fi iihes away From iheopamp, provided the decoupling capacitor is placed as close Eo ihe op uni p as possible, ty 1 ay e l her with N5 determine ihe amplification. I hr- inpul of ihe opanip is ihe nude with ihu highesl impedance, the oulpul is much lower impedance and ground is low impedance os ■well. The- input, therefore, must have ihe shortest connection. Get cracking We'll now get fo work, kee fl- ing ihe above information in mind. A lilllo bit or searching on ihe Inter net will quickly pio- dure a number cl iree nemo versions of nice printed circutE board layout software Al the end of ihe article we have included a few links lo gc-t you storied. When designing a PCB layout you storr with the fixed con- straints. These are the compo- nents (or size- of the? PCB) lhat for one reason or onolher hove to be in a fixed location Whan a potentiometer has. Jo protrude through □ hole in ihe Fronl panel you could pul 4 any where on the PCB, but in (he end it still has la fit behind the from panel, so you may os well slab -with lhat Gtnerwise, any utlie i wen I. would simply he □ was re of "ims fallow this by temporarily plac- ing all the nlher components an iheir Tiasl ideal location. if is all right lo pur ihem on rop of each olher, this is nol yet the time to make compromises (Figure 4) C2 and R3 are as close as possible eo pin 3 or liui JC. R4 and R5 os dose (a pin ? as possible. You will now notice that you have- to make choices. R3 can ba placed close to pin 3 or dose lo Cl . In ihis case we always chose ihe shortest trace For Ihe connec- tion r vith the highest imped ante. Ihis is r after oil, ihe mosl sensitive point tor picking up interference 1 : C l h a relatively low impedance Ha ground so that side of R3 is not tSmi criti- cal. The impedance on the other side of R3 is definitely higher This connection is more sensitive and needs tc be kept short. This is also Jrya for R4 and R5 (R5 is connected cm one side lo ihe relatively low impedance of the op amp cut- puij. That is why it is beiiei to mok-Hi the signal palb. ot ihe 1 Doul?i'e- short as possible Power supply decoupling capacitor C5 > s o fjltfe on its own in the schematic, faui Has lo tjc: plowed os close as possi- ble to pins A and 7 ll is nol imparton] if il is closer to either A or 7, only the total: length [oreoE] of the path mailers. If all of this is becoming too much, don' t panic! Remember three things: - place decoupling compo- nents close to the lead - keep high impedance Irocci as short os possible make a star-point For ground connections * * . In general ibe- following applies; keep the area of loops as small os is possible Wrapping up Continue by placing ths? com portents in their final location (Figure 5} If you ore short o? space, check if the following tricks are of any help: - Use SMD components. The 5e are smaller fond therefore better at higher frequencies} ihon leaded component and can he placed on the bottom of the circuit hoard, 50 they do not occupy space on the component side In Figure 2b you con sec that with rasped la ihe area □n 5 MO decoupling copaci tor is absolutely superior to □n ordinary' decoupling 1 2a} capacitor. - Split large capacitors into two smaller capacitors.. You Can quile safely place rhe decoupling capacitor wirh ihe larger value a little br- iber awoy because ir pro- vides for the lower Frequen- cies. Place o small (for example 10 to tOQnF| capacitor dose la ihe ccm- ponent to where the power supply track runs. Finally another Few tips. Cuiv't give interference an opportunity lo slip J pasl r the decoupling components. Fig- ure 6 illustrate s what we mean by this. If yt iii o*s designing □ double sided FCd, then it rs u&uol to reserve- one side as a ground plane. This makes the layout easier ond works very well from an electrical perspective, because ground Then bteomes n real ground 1 referent; i?] us much as possible When using leaded components each con- nection to ground is then made automatically. With SViO:.- you will have la make o manual connection wiih the ata of an additional via [a connection through the board from the top to the bottom side} which must be dose to the ground pin of the- 5MD component. II you don't do this tfiB length af the ground Irace could become toa muchl (MHIEKSt PCS layout programs: www, e w be u nope, t □ m/ www. c rrc til tson I ine ,n? l/ down t oad /cot/ 4 Wvw.niccud.com / ww w.fran kl in- in dustri os.t o m / Eog I e /starfeogl e. h tml www.n read m/down loods/o i cadi its 1 Q/defoult. a sp www.feth 5,n!/prqdyc ts/ eda /pc b fay a u I www, i b fried rich . com/en g ! rsh /eng I vordown load >btm www.vego.nl/1 4/midden. htm fit t p:// ti !i yc □ d. sourcefocg e. net / www.boos.nl/ ” tn a /-Lifur-u itatufmenf Vre hVriV expbw tb& C Ort/iis-irrp concept a f ground O f/ttic further We wi 1 ' oh-v explain rhe principle of jtnr-ppi nJ gtavndh. 56 ifailer ihrl’c - ;i j.'fUC' QUASAR electronics Quasar E feci ran tts Limited FQ Box 6935, Bis hop 5 Stanford, CM20 4WR Tel: 6376 246 192$ Fan: 0870 463 1045 E -masl : sales^qua sare I ect rofiicsxom Add PBf 1 u liI.’ UK «jidrii or lid Clg^ Scsnrdfd -£ 4 . 75 , Next Pay flRSUf-fd E2ifl) -£7_9S, Eu rap* ■ R«i of World - es S5 lor jfcr •-■ i! 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Oe*cnpU(ms & Photos Kit Documentation & Software Ochtnlcud* 2 /JKIi - . :'i !Sf elrrlPDrai 57 Delphi for Electronic Engineers Part 2 - Programming a calculator Herman Bulle with thanks to Anton Vogelaor In the first instalment of this series, we introduced the Delphi programming environment and described several examples that illustrate how to program in Delphi. In this instalment., we lake a more detailed look at the design of a somewhat more serious program. Our project here is to construct a simple pocket calculator in software. In next months instalment, it will be expanded to include a keypad that can be connected to a serial port to aliow the keystrokes to be read by the Delphi program. 5B t'lilDI tlcttJMl'tl ■ WU& This, project consists oS three components - The presentation foyei, which shows the result on ihe monitor. - The driver layer, which provides the inter bee with ihe hardware [ihe key pod) This layer will be described in ihe next instalment - The promising layer, which is the software ihul simulates the opera! ion oF a pocket calculator As most pl our readers are probably relatively unfamiliar wilh Delphi, in this iristahm-ni we focifs an the design oF the program and ihe presentation layer. An nSiractwi? graphical user EnferFar . [GUI] farms an important part of ihu overall project. Ultimately, the success rjf n project depends heav ily on rh« presentation. Nobody won Is to have an ugly DiY ■amplifier in I ho living roam, even i( il Fias gu] standing per- formance. Ihe same holds rrue For soFlwan.- project", The end rc still shown in Figure 1 is obtained by placing various components sequentially onto ihe screen. In thn fol- lowing descriptions, we use Windows and Delphi terms and explain them os necessary Presentation !ayer After Delphi has been started up, a Form object appears on ihe monitor. This grey window is where you will pbee vur- ioui components from the tabs in the Com pone n! palette Using (he Object Inspector, which is also shov/n on the screen (usually ol the lower left}, yo.i can change. Ihe prop- erties oF ihe window- and all the components you have placed on the window. First, use Nome lo give ihe Form a unique name (such as FMoin, ns an abbreviation of Farnv Moin] locale she properties Width and Height and assign rhem values cl 30 3 and 360 pixels. Next, find the Color property It you click on the small arrow Id ihe riglil of the input hdd, a drop-down list will appear wilh a several Windows colours, and you idn select one of them, if you double-click on ihe inpul held instead, a colour dialog will be opened to allow you to choose any possible colour. Choose o colour you Find attractive . Naturally, it's heller to give the numeric display a different CO'loui To do this, you have to give part of the I arm o dif- ferent colour. This can be done by pfodng □ Pone! on ihe Form You can find a panel object in the Component phs last number la the fesull, and so on. This ecu bo done by introducing an auxiliary variable of type Boolean, just as in digital electronics, this variable can lake ori the value TRUE or FALSE Declare a variable EnliyBsy Boolean with on initial value of FAISF (see Listing 1) The first digit is rami in, I fie con- tent of Accul is copied la Accu2, and the digit is placed in Accul After this, the value of EntryBsy is set to THlJE When the next digit in read in, the procedure sees that ihu value of EntryBsy is FRUE. so ihe above steps are no? exc cuied Instead, the value of A ecu I is multiplied by ten nnd the new digit is added to the result. The complete procedure appeals as Fallows procn duett i xn .&tfdAccn fx: IrL^eusis ! ; begin if ZnLrySay - FACES ttjnri htt^iti Accu2 ; =A ecu ] r AcCUl t*JCj Entry £*>-: = TRUE : end aine ficcti 1 : “ I-5*Accui+X; end; jMote that all keywords are shewn in boldface A keyword is □ reserved word or symbol that is recognised by Delphi os part of the programming language.] New you con process tfie resuli of pressing ai button as Fal- lows: select a button [such os 01ril) f go to Object Inspec- toi / Events, and double-click on the input field ntixl ia OnClick. The Following procedure will be generofed aut& rnatically: uroeudgtc TFr 1 . n,?.- n L Click ^SEuder; subject. | ; begin end:; You oisa have 1o ensure thol ihe variable X is assigned a value before the procedure is called The procedure hns ill ready byrsn generated by clicking on ihe OnClick event of button. Ono possibility would be lo include the following statement between the Begin and End keywords qf the pjo- cedure: fiddjfsrcut [etnij .TaiJ i // use u,e isl| nUEbcJr 0! th?j tnrttoD Hi is would havR to be repeated for each digit button, which 'would yield ten nearly identical procedures. However, there's a shorter solulion As you con, srk uie procedure includes n porameler named Sender This pummeter Hdte ri^trEoic ] 2G0S recede!* the properties oF ihe camponenl lliol calls the pro- cedure You can thus ensign AddAccu □ syituh-le value, since you hove already assigned lire tag property a number in the ronge 0-9 AdiAccu 1 < Sejjdt-j a- TCOrpn nent ] ,Taq j - Now you want to have oil ihe digit buttons point 1o lliis pro- cedure. Far sach digit button in turn, go to ihe OnClicIt event and click on the button next to the input Field Then select tiie proper procedure (BtnlClk) A her this, you still need some means to show the assembled number on the display (see Figure 2\. As this has to be done several tinner in various situa lions, you Con generate a separate proce- dure for this purpose. Include the procedure Scree nR eft toh in ihe definition and place it in the liripfemertiaiion seclion procedure TrHai n .Ecrm-TiRi."; tuBh ; begin Libel! .Caption := lnt~ oS nr t Actual i ; end: The Fine lion InfToStr integer to siring'] conveys v number into a line oF text (lexr siring), and this text string is assigned to Label! Coprion. Fhis causes ihe FesuJl m ho placed on the screen. Processing the operation, buttons regimes a small hick IF an oper alien button j+ r *. or / ) is pressed, processing the operation must nol be executed imme-d lately. Instead, il must wait until ihe = button is praised, This means you )ravE4 lo remember which Operation button was pressed. To do so, declare an integer variable; BuifcitW Yj crifc BaUfaVA ati n Cuscrr. rih.itft ' ji: ! ■ V 1 ^1 ^3 CLka C ll^ri ■ rE b:- I .’■! soesi P.r^.l ntFAULE.CMAnS R us) pjtl It MU fi USiSr.J 5“ _ -■ L : 'i -J *1 3 FTr^DC-jE* J Evrrib | Figure 2 . Settings in jf» Oity(=cl h f ffwi AJig n property for the iabet is shpwfi ar the nphr Generate a new procedure that calls ihe procedure lisled abovu. Process Er,g: Integer; The +, - 1 , and / buttons have tag values of 1-4 and lire = button has a lag value of 0 Generate a new procedure ihal uses these two numbers: pro cedura LTHellji . ' a i n a tec 1 let | Sfl mi ■ ' t : i Ob jeci } \ begin Prooc l= sMuEberB i ( Sender a a TOor-fujncn C J ,7 ng] ; ScreEmKefreah; eod- pracedu f t TT? * -« ■ . - - :.. - a b sliumhe cs < r roc : 1 n i&ge * j : begin case Prcceaslnc el ! s ■' CCM 3 : ■ Armu2 + Aren l r 2: Actul :=Accu2 - JVccu I * ii Ticcul ["RCfi'-Jj ' AtCnl; -r Aecul : =rcunrf r, Ac era 2 ' Arcu] j ; cud r Pnoceajing:*proci FtittyBay := False; ond; Thu variable EntryBsy is sel to TRUL lo unobb ihe cok;ula- lor lo again aext jpi a new number I his procedure is called using a procedure ihoi is linked lo un even) Mow double-click an the QnClick even! For ihe 'add' but- ton. Up Eo now na value has been assigned lo Aceu? The Sim- ples 1 : approach is iu include a fine in ihe. AddAccu procedure to copy Accu 1 lo Accu? ; Accu2 := Accu r j Now select this procedure (BtnAddClick] in the OnClick event lor each of ihe three other dperdlioti buttons ond the button, in she mine manner as described above When a program is started, oil of the variables ore set to zero | Processing = 0). When the * button is Fie si pressed, ihe value of Processing h initially 0, and rn ihe PracessNumbors proce- dure it is assigned the value for addition j I \ When inis pro cedure is exea,i1ecf the second iimo, ‘he oddiiinu is actually executed and the resull h shown on the dispby. You Ye almost done row; only the Clear button still has to be assigned a function. By now, you should be Familiar with haw to do ihis, so iT shouidn'i tw? difficull to fill in this proco dure. Simply double-click on ihe OnCfrrf: ovanl of the Oemh button and seFect ihe BlnCfrCFick procedure procErd ure 1 F .Main . Bi nC 1 rC s i c f Sender : lOS j eot ) ; begin CltrfirACcu; Screenftefreabj sod; Figure .7. IYc? Sp^irliiCC'iTi r'cofj fj tocuttx/ on the Additional kib at tite Cawpcntmi poleHe 7/J&05 E-’jilsr ekrtw?;!! 6T lh?5 placed lto calls OacrAccu to sci Accul v\J Accu2 la itfir'O ood 5fct EnlryBsy to FALSE. p t: nceda t e 7F VJ: i n .C lear Ac cu ; b ■. g i □ Accul ; = G; ACCu 2 ; ■* Or EntryBsy : =Falr,e ; c-ne : Listing I shows rhc complete program. including dll ihe cdfn pOfi fin’s tha! have bEfin obdod manually'. Now that I he program ts complete, you :on run il and lesl whether the calculator works the way it should. If h does’ n't work properly the first time, yav should firsl check the iBitings nt the 16 Speed LlutEons,. Verify fhar the name, lag and On Cl 1 1 c It event values are entered correclly far each button. It shou'd be noted that the calculator is siili i Other primitive in its present form since it can only han- dle whole numbers \na decimal places]. However, you shouldn't let that spoil you programming pleasure since it's jusl O jt{jfh In this in.^tulnnent, we have devaled considerable clfcnlian to ihe design of the program in aidi-r to Familiarise you with nil :he commands and procedures. With otl lhai out of the way, in the next inilalmeni we con carry on with connect- ing □ keypad to the serial par! of the PC Exchanging dttla between the PC and ‘he keypad is on rmportani aspect of ihis next step. Listing K Complete listing of the calculator program. Unit Calculator; i fi fc ci r f a co uses M I r.J civ .i. Me S3 5^^ -5 , By SlJtl 1 a r Vat louts , C 1 as se s r Graph \ c f. , Con t. rp 1 a , F o re ■■ , &ialoqa, Huttons , Stdttrla, Er-tC t r i a ; tipc Tl-'cialn - claastlToi : Pninelii TPanoL; LaSiellt TLabel; Btnli TSpemlEuttan ; 3 tn 2 : T3p= etifi a tton ; & L ri3 s Til pa ednu t ton ; Bth4: TSpoedButtob j atnSj TSpo eicu tton ; btn£ : TSpeed Button; H L n r ; T5 pe j n u L ton ; BtnE: TfineedButtOE] ; ts t, n- 4 ? j Tfl pendBu uon ; rJt.nl Gt J'ipeedBut too ; Bttllli TSpcerdButtObj Stnl2i TS pc sriau tt on ; Btnll: FSpe edButtOft ; 0 1 d I 4 t TSpe eda at L an ; 3t n 1 5 : TtJpc edHu 1 1 on ; mtnlfii TCpeedflutUm? prc-rciu re B tn LCl i ck ( Sdnde r : iObject J ; p reCcdu r« Bt nc ^ t C 1 Lt r. \ 5 1 ■: n i.‘ - ; TI3 h jet 1 . I ; u roc edu re Br nAddCli ck. ( S □ r.der : TOb j ec c ) ; pti viitu AccllI r Accu2t Integer; Entry Bay s Boci^An; Processing; Integer: pro co □ U ro Ad dAc c u. { X ; Integer); procedures P ? OCCS B W ! i itbtt I'H [ p ru C i "i.Lt>.ge> ) ; pro ce dura ScrdenRef resh ; prsefidpra r earAccuj public ( Public deelarationfl. ) end I vat 1 na in ; TEma in ; lap I e cent a t ion £SK » .dfm)- pro e edu r t- T r'tfa i n . Aad dAc ca|X; Integerj: begin if EnLryQsy - FAL z-i'. then begin Accu2 := Accra!’ AdCUl 1= K; Entry Boy := TAUT:; tpd i'J-GC Accra 1 ; = 1 0 * Accul -f X ; end; procedure I'FHsi n.-Prorer. r be t -. r pr : Int ege: i : begin ease rprceeaaiTig a! 1: Accul ;= AccuZ 4- AcCul; 2 i A c ca 1 i= Aocu 2 - Ate □ 1 ; 3: Accul i= Accu2 ’ ACCUl; : ; A con I ? rcana LkccjZ Accul); end ; PrOcCH sing : = p roc; Entryasy : = false; epd ; p roc ee uro I ( M ai n + V. la ar Arc u : begin Accul 3= 0; Accu 2 3- C; Entry B gy ; ~ FjIgc; eud; procedure TFiLdiri .ScceeuRef re ah; begin Label 1. Caption TutToSt r{ Accul J cud; procedure TFainla .BthlClick£ Sender : TObject ) ; begin ?> lr| r.cru I r - enife i* a- TConpon a n i i r Tag i ; ScreenRef re sb ; end; procedure Tfiiain . BcnAddClicitf isa-nder : Subject | : bwgin ProceGstiuabera Sender as itr eponent [ . Fag | i 5 c reenpe r esh r end; procedure Tft-la i n . HtnClrClicki 3er.der; "Object i ; begin Cl ea rAc cu ; ScreenRefteah; end ; one . 62 tk:r:r : ri- ;. 2 Cj 3 Parallax BASIC Stamps - still the easy way to get your project up and running! Serial Alphanumeric and Graphic Displays, Mini-Terminals and Bezel kits 1 L> L 5 L g !l TPSf- (Pitt) Wh' r j7 j 612&64I U-, • ■ .. ■ . • ■_ • — - -• - ■_ . .. www. mi .com Robotic models lor both the beginner and the advanced! hobbyist Servo Drivers Motor Driers On-Screen Displays DMX Prafaco! D/Sound Ranging Specialist Interface-Control Modules Quadravox MP 3 & Speech Systems Sensory Inc Porollox '! Lech [bah BASICMicra Voice Recoqniii-cn Unicorn Too! Kite ' PIC & Rom Emulator; PIC BASIC Compilers Development Tools Milford Instruments Limited Tel 019?? 6S3665, Fax 0197 7 631465,, sgltjsd 1 milinst.com Replacement for Prof. Martin Ohsmann Valve circuits and radios in particular are graced by vast crowds of enthusiasts. If you want to keep your prize vintage radio as authentic as possible while actually using it from time to time you need a HV [high voltage) battery or its electronic equivalent. One of the most pope Jar types at vin- tage radio running off a high voltage iHV) battery is the valved, portable, medium- wave ar long- wave receiver. If you decide lo use a switching step- up convener for the 90-volts plate supply then a design using the usual 30 ivO kHz switching frequency will soon be found problematic when it comes to preventing harmonics from leaking mto the tu-ceiver's RF circuitry. In many cases, the problems are insurmountable This article describes a circuit that prevents ezaeby riiis kind of trouble by using a very low switching frequency indeed BO Hz (or 6D Hk)l Hus approach no! only ensures that har- monies at, say, 200 kHz remain at a negligible level, but also that an oEf the shelf mains transformer may be used, eiumnritsng the need for con- structors to wind their own transform- ers or Inductors. Also, at 50 Hz avert standard CMOS logic will be able %o revoke the ghte charge on a MOSKET at a sufficiently last rate Neither do we require fast high- voltage diodes, the ubiquitous 1N40D7 handling tile job with ease, With the above concept in mind a etc Chit diagram is quickly drawn (Figure 1). Logic gates inside a 74flCtM (C aro conliguied as an oscillator with a com- plementary drivt i for two small power MQSFETk. The MOSFETs power the 2 64 sisiiw 3/7005 T Batter y A 90-volts inverter for vintage radios ■t£V figure F Circuit diagram of r he 50 Hz switching step-up converter with *90 V output centre-tapped IVthmA secondary oi j 'reverse-connected 1 mains trans- tormoi. T j i r- resulting alternating volt ago at L hi? primary side is rect Lflh?d and Tittered by two ‘beefy’ electrolytic capacitors. For simplicity's sake no ngulHEhm tiicuit is included, only two bleeder 1 Tesisiors R7 and R9 lower Lbe output voltage under no-load condi- tions while also discharging i J i . ■ reser- voir capacitors. Tire output voltage (at the 0 and i- 90 V sockets) is electrically isolated horn the supply circuit at the primary side The inverter proper is powered by five series connected NiMH cells oi 1.2 V each. These cells may also double as a filament supply, lor example, for - E' valves requiring tj volts. A separate convener output supplies -1-12 volts obtained by rectifying the switching s-gnals applied to the transformer's primary winding, the diodes conve- niently doubling as transistor surge proi pci: ini devices Components ft 5 Figure- 2 Copper froct layout and ... and Dl prompt ICl against excessive Supply voltage levels. With no regulation available, the con- 65 i/ ZOOS -tltllsf Table 1. Measured values (6 V supply voltage]! .. component mounting pion COMPONENTS LIST H e si stars ! Rl = 1 Wits R2 - l OOkfl R3,R4,R5 P K6 - tOOfl R6 - I50II R 7 - lOkll E 9 = ieoktj Capacitors: C 1 ,C2 - 1 OQnr C3 = 6B0nF C4,C5 « 3300uF 16V radio! {dm. 1 3 r.n. Jmm lead pitch) C6.C 7 r47Qp F 2O0V radial (did 25mm, 'mopin', Farrmll « 443-7913) Semiconductors: 0 I -c 2i! ne; d: acl e 6 2 V 0 4 W D7-D7 = TN4D07 1 i ,12 - IRLDi20 (lnten-inhon.nl RecJrf er: Farndl- # 3624066) JC3 = 74HC04 Miscellaneous: TR f - 2 k 9V 3VA mains tremsbffnef r 'C3, available from Tim PCBShop, ref 4 040207 l No load Current tuFLsginptign 4ft mA 3 2-V output 11.6 V 90- V output 1 15 V 1 2-V output tended Current consumption 207 mA 12-V output., BO mA 9,54 V 90-V output (nal loaded) 100 V 90-V output loaded Curran] cort^umpl^qn [33 kn) 101 mA Current consumption (22 kflj 123 mA Current concumplipn j ] 6.5 Ln] 141 mA 1 2-V output jrtal loaded] n .2 ii.4v 1 2-V and 90 -V outputs loaded Curren t consumption 277 mA 1 2-V output (120 Q) 8.9 V [ripple Sri mV^f 90-V output (16.5 kfl) 74 V [ripple Ji mV^J Figure 3. Finished prototype of the convener Fj < jun& 4 During our search for a photograph of a real MT hatt&ry ns used jn vintage portable radios we came across fn/s brilliantly styled kit from Kit Radio Company. vortor's output voltage in dependent oil the load connected. Some test val- ues obtained at a supply voltage of 6 V are listed in Table I. Construction Both the construction and the compo- nent choice are '.merit ice! The MGS- FFB are housed in Ttexdip cases. The diain connections ate the iniercon- nected pins. The two ladial clectroiyt- ics C4 ana Cb are mounted horizon- tally 10 save space. Do not ioiget to fit the wire lint between the transform* r and T2. It you want to keep huin levels to a minimum, il is recommended to screen the entire cijcu.t using tin sheet met a! which will rbso reduce iho risk of mag- netic coupling. The hniKhed circuit lioaid is shown ii Figure 3. Different output voUages and povves s may be- created by using appropi iatn mains transformers. Warning. The circuit generates dan- gerous; voltages, tvo part must be tn-idied when the circuit is in opera- tion and all jplevam. electrical safety precautions should Iwj observed. SHEETT-tl Picture source Kil Radio Company Vvfeitorhain jiniroducJary p holograph and 'i^ tu 4) Web painter h !h :■ / /T.rjfni-.l pysi i gq I ,ca. u k / h I □ / kiErcdiocq/u k . hi m Radio kin [iruJudTg HV battery replacement KR.C-A-2], components and ffee- Canstfuctfan guides. 66 *Wtw 1/JM5 Read elektor electronics leading the way Time, Date, Weather Forecast, Humidity. in/Qut Temperature and Moon Phase on one display. PICK YOUR OWN ANNUAL SUBSCRIPTION and receive this wireless 433 MHz weather station*! Make your choice: * Elektor Electronics annual subscription (standard) You receive 11 issues, including the July/August double issue, ■ Elektor Electronics annual subseription-PLUS You receive 1 1 issues, including the JuFy/August double issue, plus o copy of the EEektor Electronics Volume 2004 CD-ROM (normal price £16,25), Your saving: approx. £10.00! Please fill out the Order Form with this issue. Subscription rates end conditions may be found at the back of this issue. * Otter available to Subscnbers who have not held a Subscription in Elektor Electronics in the Iasi 12 Months, Offer Subject to Availability. lektor lectronics ■ m- ril 1 u way E-ONLINE Free Internet does exist David Daamen Of course, there's no such thing as free Internet, but surely that does not mean you have to pay the bill? Today, with a little ingenuity and some experimentation it is often possible to tap into a neighbours wireless network, if it is not, or not sufficiently, protected. Many people use WLAN and WiFi equipment out ol the box and totally forget about installing or even enabling encryption. The result: lots of ‘free’ Internet access points! Sheer negligence and ‘Diiheil's Boss thinking'' are nol lha only reasons for the occasional hubbub tn the pros; about {corpa relief networks being easily accessible by any WiFi us^r within radio range. The phenomenon is not ;ust caused by weak encryption technologies, but also by many pri vote computer users and professional system operators being sloppy In their dealing with encryption keys and poss words 68 tJbhtt Ertdliiiitl - 3/IttDi In many cases, no encryption key is set up at oil. result- ing in a system i hat's about as open is gets and conse- quently allowing free Interne! access hy any naiMig I ho- med user within radio range. Hacking !n practice, hawfcvm, totally open systems are o rfuily Using software like 'Aimperd / 1 1 | you can get a quick overview of whol's on the air in your area, and which networks are protected The three most popular encryp- tion standards are listed in the loh-e together with the ! ess than respectful nicknames given to them by hackers — dearly, WEP is the least powerful standard. Unfortunately (or should we say luckily] WEP is currently the widest used standard — end highly vulnerable it is, see [2] and [3J. Hutting aside the question whether breaking rnro □ pro- tected wireless network is immoral ot even illegal, it is □ fact ibat free Internet access is perfectly passible. Countermeasures Of course, you do not want unauthorised users appear mg an your wsiu’ess network. Now that you are aware I hot the g rearc s I imperfection h ir. the standnrdfs] used to protect I he system, ills fairly easy Jo came up with effec live countermeasures. The obvious choice would be an access poinl employ ing WPA (Wifi projected access] based on the BO?, j It standard However, if you already hnve a router having just WEP. check if it ts possible to employ ■authentication'. Using the 802. 1* standard that's common for these systems, o nrjw connection/session key is assigned lo a user any time he/ she logs onto the network. Tries does, however, require an authentication server (RADIUS, remote authentication dial-in user service] but there are also access, points on the market that have such o server as an integrated facility. This setup no longer allows eavesdropping on the traffic c:t; tried by the access point using a previously 'hacked' or stolen key More- over. the key is invalidated when the session is over, For continued protection, o recommended procedure is to log out and on again from time ia time Besides RADIUS there are other measures that con help to increase system security, A .stem-by-step guide to com- missioning o wireless network may be found at [4] where security gets o lot of attention. legal Fine sly, we would like lo mention m fnw links to so called hotspot directories' [5, 6 7 and 9] . These are guides on the Iniernot listing locations oF publicly accessible wireless networks. However, most access painis found m the.se drrectariesL tire not actually 'free' and access hus lo be paid for Paid-up service a.r not — here, loo, poorly protected networks are an open invitation To hackers. IM3KMI Internet addresses [21 Mnwl key rerovery; nbirarl.shmop (3] WEf Crock: wctKrgtk soDttfilwap.iiBl [4] Doping your Wifi nulwotk: [5] WiR freeswl Directory: wwwifrfrEWM [61 Jhrirc Guide Id Wtfi: www.Nirere,tiHn [7] WiR ZoueFi Elder wniw.iw : fizfl i ne.wn/?nii f8] HolSpot Haven: www.lio1swlhoyen.f 04n m? WPA WPA? Vf.r&d Tq'.fi , .T- - 1 h ivety Wifi PraiEttfd Anew ‘i'vH Presetted im?!5 Yenwimi.il FI (V'.t-T t httt ftotafi I^IVornfJlA^r KtiptitYf iLV/ig/rJ Wed. noik Veyi lr,pra.^dKCUT,t| hy rotolin^ ilrmg ethj yplicr. nH (iullwrfiHitnni options T/30D 3 - -E^kliir (IrCfiGEE A9 start here PfiTCS siprr>?: t*=-M tic pw lions where white LEDs [light ^milting rfjodns| are used as i|bocStgFound[ fig hi sources. As exam pros we could mwriiion LCD ui keyboard backlighting. Alter- natively, white LEDs hove advan- tages m bicycle fights and energy-friendly podset flashlights , Ths circuit sIiowji 3il]sc allows Iwd variants !d La bulllf ■up fo Foui sufies-caruiGctsd while LEDs powered From tv™ series-connected NiMH, NiCd or alkaline tells; -up la six serieKonnected while LEDs power Ewi from ihres sahevtonnected NiMH, NiCd or nlkqhriE cells, nr from O sin- l-jIp lithium-ion cell r or the firs' ephon .| i= sufficient (o have on mpul voitoge range of I 8 V to 6.0 V Far iht sac and, u range a I 2.5 V ta 6.5 V The lf 1 $Gl042 From Texas Instruments is a PWM (pulsewidth modulation} step-up ca n vc- r l Of co n ! i gut c d as u cgn- s.tanl Fi^ed >n the hole [3\ ond ihon soldered |4f Applying l he usual dewldermg methods, the tube ts then opened |5] allow- mg the component lead la be i riser red and soldered (6| IF the hnle only serves os o Via' ihen sreps [5 J and (6] one not required N e- Mullicgie Capperset I: it con loins she special taaEs arid lliree bai s of 5GG lubes with diamefere cl 0 6 mm. 1 0 mm and 1 .2 mm. 1 he kit is not cheap (Famolij bul fortunaliily ihe bail bar tabes ere Lit so said separately ond whol's more they are easy io linrudfe with just cornman-OF^oidcn toch. Thu system is suitable for boards wrth a thickness of Lp to 1.6 mm. i n y n , Svpplrat . w'.vw. tarn a 'tinor.e .com Simple Mains Failure Alarm Jacob Gestmon Goradts A 'Mains Farlure Alarm' WOS published on page 70 of (be July/ August 2004 issue a! Iciek- Icie bletlranics Allhough that dr cuil is full of ingenuity ii may be a bit ovut the (op given ihe pur- pose, which boifs down to mak- ing n noise when the mains volt- age disappears. The uuthar thought ihe same could be achieved with considerably Fewer pads. If you compare the two schemal- Ici you will agree ihat allhaugh a to! of pail.- iiGvp. been cmilted, a back-up energy supply remains a central and indisF'Srir sable pari In ihe version pro- pose:.* here, an array of NiCd cells is used. I he aulhpr sal- vaged them horn an aid cordless, drill lhar wos binned because of a duff bailer y pack. As in many other eases, jusi two cells lamed aut to be beyond hope, the oth ers working just final Wilh moins voltage- normally present on ihe power ourlet, ihe Culls ate charged with a .small c urrenl lo keep them lopped up. The charge currant ii supplied vitl die mams adapter D I and F! I The fa(!er is dimensioned such that a iridde charge current of a jus? u Jew in A is obtained When o power cul occurs* the rransislpi in Ihe dfCuM will con- due i and DC buzzeT Bzl wilt produce ?nmr- noi. LC- . Otrct ihe cjrcL ' has done its jab — aler(- ing you (hql lhs main..; voftegs has vanished — you or your housemates will soon wanl tn silence the bujt^ei, This is done by pressing 5 I , which lakes ihe- ifoniisror's base lo ground - nKUiv-li rUkbr eliiUK&u 71 figure J With SA’Di >-op con pvf c fof of foneJjanaJrfy niio a key hh. RF Detection David Daamen WiFi detectors ore small gadgets that claim to delect wireless access points for computet net- works. The effectiveness of these devices is ceI ready covered in many Inter nel articles, but here you will find out exactly how they work. Tto buLfin willi, we opened thu first device we had tn hand; sat* Fi gii re 3 l Kensington ‘WiFi Finder'). It waa immediately apparent that it n Fairly laige number of components- Apart from a large section oi passive components (resistors, capacitors and inductOTs) we counted five transistors and throe fCs. AH components, apart from three LEDs. were surface mounted On the other side of the double -sided PCS we i =:■ i wo Wa tci; b a Lt eri c- s . Principle It soon became -c ; l r l 1 uh l the heart of the csrcu.it was an RE- dt>r>i tnr 1C made by Maxim, die MAX4003 This logarithmic amplifier ;s preceded by an input stage eunsisimg o- an aenai printed on i he PCB fol- lowed by a few Qltm and amplifier stages The. MAX4003 converts the RF sig nnl into a DC voir age with an amplitude that corresponds logarithmically to the ampli- tude of the RF s-ignat Th?; DC output, signal is ampli- fied further by an opainp (MC33202„ OM Femiconductar.i and then fed to an A/D con vector input of a microcon- troller ( MSP43GF 11 Q1 A Tfexss Instruments). Microcant roller The primary function of the controller is to periodically measure and evaluate the sig- nal strength of the input. Three LEDs are used fuc the display; a or- colour LED indi cates when a meaatirermant takes place fa shot t red flash) and together with two green F. Us it forms a mini bar giaph meter, which shows the siujan] strength as one of three levels. U is clear that the controller doGsn t luck nr the contents of tiie received signal there is nothing left oi the digital Lnfur- 1 oat ion after the detecEoi IC; just lire RF energy is mean uied. Thus became unit evident by the fact that tire clettKrtdr hlsn reacted to a Blue- tooth signal (very) near by. in practice you’ll hardly notice this when searching for wire- less networks, since Bluetooth wig rials sre much weaker than WiFi signals. Selectivity The only selectivity offered by this Circuit when t! has to dif- ferentiate between wireless networks and othei EU 7 signals is achieved by the niters Lri ibs input stage These ai« luneri to -ho band used by 802.11b and g wneless networks [2412 MH7.tc.24B2 MHz], ft is dear that such n passive filter is not perfect When -i (3 SL 3 phone (9QD nr 1&Q0 MHz) is nearby; this ml so causes □ few LEDs to Ughl. up, RF defection You may well womilei if there isn’t an easier way if you only need to me astire ihe RF' onorgv there should be some simples alter natives. Altiiough this is she case, there are slid vety gnud [wagons for using a logarithmic amplifier- Thure are two other methods foi measuring hirfh frequency power, but belli of these have l, Egni n car it rti sadv ant ag es . Wn've put the three methods in a table along with sbt 72 i^burtbikch-a i/ifflS OUTPUT VOLTAGE -60 -50 -a -a -ra -10 o io INPUT ... , Ftgura 2 . The output voffage o( a fe*j nwp is n fegranfnmit function of the RF input power. important design aspects to ahuw you bow they compare Thermal defector The thermal deiactPt is the most conventional. The RF power is determined Gam. the Ufi'F it. temperature of a icsis- txii that ia fed with the HF sig- nal From i he table you can see that this option scores badly on all fronts, apart from cost The main disadvantage is that the thermal detector too slow lor use as a WiFi detector. Diode defector Although the diode detector may appear to bo a ben tit alternative at first sight, the advantages it offers over tire log amp STe not important in this application. You may argue about the power enn- SLU.npl.iui.!, Inti n good temper- ature stability it. definitely nut important in ifrjacase. Al about the same cost, thu solution provided by the WtFi detector that we opened offers the sm allest FCE with the best dynamic range end a last reac- tion tunc. Furthcrmoic, tbir aitcioooniroller is used to per- form multiple functions. Not only does it take care of the actual measurement, but it also drives the LEDs and implements an auto power- off function. £3=10-1 1 Dsleftign prEnripfi! thermo! EKttJ" Lug urup Sbt al pa large mid jin vnc3 PflWfcr tc-iiiuM! f:lia;i b$h tew rwtJwin Tbnrd Hqtf [y 5hh1 goad ETtmtiJITi R ■:■ c c 1 i c n l hi t illilLjECOrdi rakrmeforHk < Id Jfi. Dysc-mfe tong* JO 20 d3 k 100 ii3 (□si mtdi'jrrv LEAP IN STROLLERS A Our range provides \ ‘ • The fastest 68 QGQ has ixteraiv; i^O:* Serial, :DA, SP1, IK Analogue, i me rs/ Counters, RTC etc • Large Memory Capacity: ¥hs h, SRAM, DRAM. •Supports:- Mono Sr Colour LCD's, |r Touch Panels & Keypads, Very Low Power |T DEVELOP! ENTX d ■ Target easily & quickly. \ Ull.ANSI C ’ compiler, assembler linker all Windows32 based. ;>!* j Source Level Debug. ! ■ Full Driver Support with Libraries fwlifrime Multitasking OS with a free run time licence. JLL “REE Unlimited email support./ www . cms. uk. com 500 our web site for full details CAMBRIDGE MICROPROCESSOR S V STEMS LTD Unit 17-18 Zone *& ChdmsfOFd Rd. Ind, Est. Great Dtinmow, E^Cst CM 6 1 XG Telephone, 01 371 875644 email: sal 05 @tms, uk.com JjTilOi - dtihir dHirnia kitchen table Eduard Heger If you are not lucky enough to have access to expensive test gear then lamp circuits using LEDs offer o good chance of success and allow a little bit of electronic experimentation. One of out leaders has come up with this simple hut useful addition to the bedside table. The lamp is activated eithei by pressing a push button 01 auiomalicaUy when the in-hulk micro- phone detects a noise Once lit the LLC remains on in? a predetermined time. The circuit has quite modest power requirements and faux lechntge- .tii'le N i MPT cells fBTl) will be sufficient to power the circuit fm a couple of months of intermitte nt use before they need to be lopped up, The complete circuit takes around 400 pA in standby and ?A mA with the LED burning, Ttie microphone requires n connection La the positive supply vns Rt and the cue nil diagram (figure I) shows it AC coupled to IC1.C. The microphone sen- sitivity is to some extent governed by the value of Rl. LED Bedside with turn-off delay 74 e fill or EledlDoio - 1 f fflfl 5 figure I. A value of 15 hi 3 is recommended but it may need to be changed to suit the sensitivity of your pen, ecu lax mitrro- ptione capsule. At maximum vtty the LED was triggered by pressure oil i he mi CTO phone diaphragm from a draft of air produced when the bedroom door was opened! Capacitor Cl is used tD remote tire PC compcmeui of the mrcraphosiG signal white R2 ensures the resultant AC sig net Es referenced to earth potential Resistors R3 and R4 form a potential divider to provide the voltage thtes- hoid at the negative input of compara- tor 1C3.C. Whenever die signal level produced by the noise exceeds Mils ilueshuld value the output will go high and s w Etch on Tl G apactto r C2 w i 1 1 then he charged and the voltage love! ort die pasritivo input of IC1.E1 will use cxp-onemfciily Pressing pushbutton 51 will have the same effect because it is wired in parallel with Tl. The char giug path of C 2 has no series resistor so even a very short duration sound vvtil E:h sufficient for C2 to fully charge. ICl.B is configured as a comparator with resistors H7/R0 foiminga poten- tial divider defining the threshold vol- tage of 20 % of tlie supply voltage (about 1 V} at the inverting input. When £32 is fully charged it tokos around 1.5 min for the voltage to fall to tins Et-Vel while discharging through reslatpE R6, The last oparnp IC 1 A is configured as an amplifier tog fit hot with transistor T2. Tire LED current [and hence bright- ness l can bo altered by changing die value nf Rll (I L[ .- D = 0.4-1 V7H11 J The voltage developed across R" 1 is used by id A to control the conduction of T2 in a classic feedback configuration. Ttiis ensures that the light intensity of D1 rumatns constant even when the ■ battery output voltapp sinks m the shnrp 'knee' in its cbaiactonstic. Gen- nector K1 nltows an external chargor to recharge the cells. TjieFCB component placement (inclu- ding a socket for 101) is shown in Figure 2. ft is not necessary to fit any wine links ami apart horn the -semicon- ductors there is only one polansod component (C2). It may bo ten tilting fate but there is hardly any opportunity to tit any component incorrectly! The LED in spidered m place once the PCB is fitted into its enclosure and the LED Turn off delay calculations The LED i urn-all delay nm^ is reialivaly utrtplE* to colculose :r chong^ if required fh& output of cdmparalgi 1C i ,0 remains high ds long o : . ihe signal on ilm flidn-frivQiiing input Ipin 5| dbc^u the wollaiji? On ihe inverting input (piri 6| Tlio voftcrgc leva! oi fii i 6 is given by: xFta/l^+fiB] •be voltage ncrOi r . Ci hi -rdid- gu: according to the natural logo rilhm function - Rearranging ike R-qunlicm fm t. b>a / U 5T1 = e r/ K4C? Jn|U 0 /U BT |f = -l/R 6 C 2 t = -HOC 2 ■ In [U C7 / U aTr ) Ur-: Olid Up-.v ; 6 should he lequcjt ‘O-iubi'i ruling: 1 - -RdC2 •: In [U &TS X EB / |R7+R8]) / Ugtil The fcoff(=ry vohoge cuu be cancelled from Hhe eqt/ali on -o rha- ;he lurn olf delay liT.e i> -Italy d u pc ri do nl on Itie resistor end capacitor uak-esl t - RdC2 x In (SB / [H7+R8H Sulhsfi luting a dual component siofuoir we get t = -IDd - 47-: TO* . In -f I CP / 4.9 1Q S | = 75 s 75 E/JG 05 #jtf tlKlranits positioned Lluough an opening. A reflector cen he fitted to help concen- trate the L£D light Wire connectioiiB to the FOB can bn made via solder puis, it may be possi- ble to connect the charging socket and pushbutton directly to the relevant pins without the nsed fur wire bin tins will depend on the typo of enclosure that you use, The [mciopbone capsule cam ho mourned inside the case hut don't forget to provide an opening to allow sound waves to reach the micro- phone SCTHRi'll COMPONENTS LIST Resistors: R 1 = likfl R3;RS_R9 = looluj S3 - 221 li R2 = 5kL36 fid - 6km U - 1 Mil Ftgum 2. ft/ = 3V0kiJ RIO = IflUl Rll - I6fi Capocftors! C 6 - 22rf C.2 = 4/jjf 16V radial Semiconductors^ m = LED.. while, e.y.. Conrad Lir.'-utroni': ; e aulbor over the past 15 years, has conirifrured to this revi val This book explains the whys and wherefores of loroidal output translcr- iii ers at various lech- nlcal levels and oners innovative solutions lor achieving perfect audits qua lily. ISBN D 905705 n.l 7 £0-1 Papes 25 S5 (US$52,Ml) The name high- and equipment is a good indication of file pr -:hs charged lor it hor iiinse who cannot, or will nab pay ibese high prices, there is a solution offered in this book: build your own at cons ria:ah!a cost savings. This book is aimed mol only si Ibis sectoral ihe market, but also cl ihe many enthusiasts who wan I to be able to experiment and lu make their own modifications to ibeir high-end equipmenl. Contents Indude solid-stale and valve preampl riera and power amplifiers, active cross- over tillers, an active sub woofer, a baa dpt to fie amplifier and more ISBN O 905705 40 B 262 Pagas ELI 5. 55 (US$31,(H)> 76 til » Iih shctiaaiH - 1 retronics ronics retronics reti Marconi TF1 152 RF Wattmeter Jan Suiting In line with this month's focus an all riling:- Wireless I om coveting a vintage instrument I hoi has given me many yean of excel lenl service ond peoco of mind at a very small investment indeed. II you Itfce 3o work wilh transm friers, large or smalt, the most .important thing la have an the ;a&i equipment shelf is net □ hefty power supply, na! a spec- trum analyser, not Teflon himmer taok ai any new-fgngled b.l of LCD mull i merer. Forgot abyut these- invest in a proper dummy Toad as it will give yaj a feeling of utter confidence that the {expensevaf transmitter is [I] always, properly loaded and (2) prevented From radiating away. Much to (he amusement of same of rny mexe OC-indined friends,, if unknown equipment lands on my benchlop I invariably hook up ills wattmeter before anything else and then carefully inspect the coax lead and adapters if applicable, bought my Marconi TF1152A/1 "Absorption Wattmeter a bo u NO years ego Eoi j List L-zidtn 20 pounds ham an electronics surplus store. I guess fl was built in I ho early 1970s. Fram the available stock in the crammed staro I wos. car& hjl 1o pick a IF 1152 wilh a not too clean face but clearly marked J 50 IT above the N style input socket. These maters aba come in 75 Q guise which I believe is mostly for use in pro- fessional systems employing 75- II look cables. Yea, N connec- tors aba exist in □ 75-H variety end only experts can see the dif- ference villi 5 CUT counterparts For years I dreamt of awning a Bird Termalino' |ria typo) wattmeter wilh q box of those beogtiFul plug-ins for various bands and power levels. To cut a long story short- too expensive for me. The Tl 1 152 combines I ha func- tion:: al wideband dummy load nnd accurate RF power meter in □ singte lightweight case painted a dull tecfinr^grey' Mine has a I 3-digit number engraved in the front panel which I suspecl h a NATO stack number [rxs.n.). The instrument has two swilch-seL-c- tabfe power ranges with match- ing meter Kales: 0- 1 0 W and O- 25 W. Its frequency range is 0 lo 500 MHz. The size of ihe instrument and its sturdy carrying handle belies its weight — m a positive way because thfi TF1152 is very easy to carry around. I have used my IF I T 52 to test ond adjust more PM.R equipment than I care to remember, also on windswept hills and lowers and in radio amateur shocks covered in thick ci^of smoke The rfietef needle will faithfully indicate 200 mW or less of RF power even on 70 ems, Ihe needle response enables you to do lx PA, trimmer adjustments quickly and wilh confidence as yc-u can observe the power ootpul tre-nd' — try that on a modern instru- ment with digital readout. J must admit I never bothered to look tos-ide the instrument umil J started to write 1h is article Ihe wattmeter being of the absarp Tion r type, il cc mains o thermis- tor bo! a me ter elemenf in d glass encapsulation This element is electrically incorporated in a bridge efreuil together wilh sev- eral calibration end 1 1 hernia I J compensation elements. A small bead inside ihe ilie.-mFstor .-on- lists of a compound of metallic oxide? possessing a negative temperature coefficient al resist- ance. Such d ihermisEar element is very hard if not impossible to obtain us n cnEKiff ond certainly outside the reach of the average hobbyist. The 5 Cut Kr land inside the TFT 152 looks like a tapered tube running almost the length of rlic meter's cose (see photo- graph). Hear the end, 1 was only able to see whol looked like n ceramic insert Ihe V5WR of the iiiyi reli bus load was kJijfiJ 'io be less than 1.10 across the band, ilis accuracy of an RF wattmeter F R 1 = 1 00 Q while for lamp La?, R2 200 D , Both resistance values are applicable ai die nominal lamp power I he dtemating voltage source show supplies a voltage U * 22.63 V ai a. fr equency of 50 Hz. The value of capacitor C is inch ihal the component also represents □ reac- tance of ?00 Q at 50 Hz. in other wa rds, C has a value of 1 5.915 pF Initially,, switch 5 |s opened (as shown in the diagram) and the voltage source supplies rt voltage tj causing lamp Lai to be- supplied with current and the? bmp to light al a certain intensity. Meat, switch 5 is closed, which bods us to the question; After closing the switch, will the intensity of lamp Lai increase, decrease or remain the same? Followed by ct second question After closing the switch, which oF the two lamps Lai and La2 lights brighter? Quixz'away l ) chic I wiffsl ^ Send in fhe best answer to ihis month's Quizz'away question ond win a PS603 HCtePOWER [0-30 V/ 0-2.5 A| bench top power supply from Vel lemon worth £65 A answers of e processed by Martin Ohsmann in co-operaiion with Eleklor editorial staff. Resulls ore not open to discussion or correspondence and a lucky winner is drawn in case- ot sev- eral correct answers Flea 5 e send your answer to this month's Qeizz'away problem, by email Fax or letter to; Quiz* 'away, Etektor Electronics, PO Box 190, Tunbridge Weils INS 7WY, England, ? 0M (444) iORSBD 2Q061.O. Email: e d itc Ks el eklo r- c tec t tonics .to,u h , subject; 'quizzes way 2-05'. The closing date is 25 February 2005 (solution published in Mia re h 2005 -ssuej. I he ouicame of the qu;z is final The quiz Is no! open tc employees al Segment b.v.„ ils business partners arid/cu □ssacjqted publishing houses 78 =!fltr:i s«5r;-..« ?/ J0O5 As of the September 2Q04 issue Quizz'away is a regular feature in F.iekfor Electronics. The problems to solve are supplied by Professor Martin Ohsmann of Aachen Technical University. Solution (p, 73; Wond rous light Chain) Surprisingly Few coituc) answers were received so ihe Eighl chain musl have been 'wondrous' indeed to many oE you However n few often tive r pen-far: were □ h!'.- In discover, by 'leversu r E-p; un i-ng ‘ rhor the voltage source used wu; nut an ordinary Ira reform or con net led ro phc mains bur one producing ar F:F signal ol (about) lit,-' 1 ? 6 MHz and suppFymg a nominal aujpur vollogo of 3d vcills inks 360 a AM 3.56 MHz [on ISM Fre quency oFleu used Far RFID), He wave- length in vqtuum. kp, equals t/f or 22 I 1 m Consequently the cable length is rial small relative la the wavelength, forcing us 1o dascribc- the operation oF ihe circuiP in terms of transmission line theory. I be impedance at an unshielded 7w.i n *eri- poir Ethernet cable (i.e., two wires] is about z* 3 20 11, which aqual:- the infernal resistance oF the lamps ar 12 V / 0 I A = 1 20 il In olber words He Eamp^. am impedcinci=-mntr herl in He lines S inc-e Ihe propagation speed a! waves on :ho twisted pail Fines is about 0,01 tunes the speed oF FigbP, a cable with o length l of 4.5 m as used in our Christmas free represents exactly a quoi !er wave f| = Xg/4)l This should start same balLs ringing In ilia Rh engineering depariment because the wires !a ihe tamps act as quarter-wave transformers figure 2 illustrate whnt happens The Imped Crfite seen qI the powered po mi 'S' depends on (he resistance J? used !o Jnrininaie ihe transmission fine, if in ihe case of He correct lamp connected up. (4 = zq then He line i* perfectly rri a tell L-d arid an impadonCG = z ; -, will also be '^en ol iho Fcctd paini'S'. How,, il R becomes infinite, os m ihe case of a defective lamp, the current ai ihe end af the line mast be zero, while it s at maxi- mum til lire feed paint (lower drawing]. The vahage bos Ha opposiJe behaviour, reaching zero aP He Feed paint and max rmizing ol the (apen| end af He line 1 1 ‘his way. a quprler-wave transmission I 'lie- Iran i For ms an 'open circuit' ol iho end into a 'short circuit’ at she Feed paint Thfr line ,tse!F then carries n sa-cnEFed ' Standing wave", nal ro live yin q energy in la d direction but cd using energy So be uxcFianged batwuon (hr: electrical and me cm eric Field components ust as with O resannnP circuit . The a have aft^cr allows us id explain the operalion of He- Won drous Light Chain in o simple and straightforward way. Wfi are loafing at ihr^e lamps con- nected lo an RF source via wire pairs acting as quai Ilm-vvuvu transmission lines. Close io Ihe vollage soufcc ihe three- fged poinis ars connected in series. With all lltiee lamps intact, Ihe circuit vvitl function ml qs ony primitive set of Christmas tree fights. However, if c Inmp tails . ihe open-circuit condition eil ihe line end is transformed into □ shon circuit at ihe local read point. Con- -sequermy the source voltage will drslrib utfi across >he remaining network of two 'ompf., which will Sight brighter Demonstrating the Wan'drnus light Chain has rr perplexing effecl an c ustahaut any oudience. As un inteleslirig vurfely, sue whal happens if you connect the cables tn parallel at the voltage source or she wn in Figure 3 hat crjmp?etene-M' ^cika we stiriuld finish by adding I hat a qudrter- wave sronsmissian line transforms ifiorl- c-rcuil a i He end in.ro an open-circuit can ditfon al ihe Feed pain I All this may be Fond in any lExlbocA on RF engineering iiwjfw.nrt t n rjuubk! Si doth 1,0 mm, Platocl Through, Grpcm Solder mask. 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Jj . r^.'L- CWDd •.: -:j| .xflili.J hi, ■/ e-jr frt-n trnn crv>:.' j Ir* ; rr-if t fce usrd l(i may UgOi ir/.’.*S Hifarer Cf>, - Tift aftJrTl Jct i PCS nr--n b r- 7 ; m'ji- j£j! mtr -Jr-: ^vcCigri tf-= =-rrlci Rr.;:? rr^Ff Be n Ifa .fii'i -fFftMfa Wil rV; hfisjTl lyt-- ir.cieeeif&Drin i'i l _•: c- e : lEUf-pa- eimr*l hea tre r .jn n c j^s r- ptf*3ftE:i i*i±n“Ee -ri b [rm t.ttu jT-y£ rj t-r .'t [W ?■' tiil: is 34 iif r-L- isiui... ie. ri litnra t -.viL'-ra taep*] ei :•«: jj r J .- . . .'. lM UHebfin eteutl, •-««-. j l.v =a» ns ftii (V4 rS I'Tj p J4 y— ; Ttnrril r?U fS ;'l M TiLi tt 1.1 hi £J''X»J. PAST ARTICLES re rtarrjaao tn HSU t-li-L .Ititr 31 tiib -1 nd Jo- ---;-;.- ;.- ■: ;.:ryi ■BiMOj MKif; mol vmQUKse- f*ta aaeieibP. 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CO D?r 1 VI -t 1 Rji, ts«e 5 - 0 r->* 443 565 (Eli 1141 flSC3fl5l-1ZPC fln&5nT«--> 845 ISS Ruimleig hi\ t>lsfl5ai 5r- DZ^P.1 1 r st arc cods 494 sts USE, Analogue Cflrvsrler g 42037^-1 FEB 1350 © D^CJF-- 1 1 &.H. te* cvh a .; WXuknK J3H*riJ2 440 S.64 (R£2r4-4i ft: :enj E =, k:,;-jt ••-■; is-a S2A5 No, 325 OCTOBER 2003 DOS- HE Signal Gfioarartof “i D3ESS4-2 PCS. iany. 12-W 31.45 DE1BW41 (I4E1515 EF-C jmsywraa 5C?55 04 65 Mmimalfel InducIrDn-SalancE 1 WElal Orlarlor ••» OSfflfifl-i PCS 845 15 85 ffillnT P^tlM PfOgrammEi © smim-ii scftMn 440 3.65 No. 324 SEPTEMBER 2003 AW Pic lure! D EnEraljr 5 CS02S:-11 i>.w. MIR 6 tti CD*C 1 m 4S0 US KSQ3S5-41 ATHSffiiSrSfG, ^usroita 15-30 3ttt 03qaSb4? ATK513CO-1SP;- jyrw^Pd lied 21 ED DTWF Flemclu TCI liphc n h Sv,!tcn ie 0M241-! 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FC0 »d5 1500 M-eI Hu fining liiil □ ^pl.i> ©020065- U Kit SOITTEICT -. +93 505 MieiTesI Chart Gcncralur © 025403-1 1 Ci'X R«; snnfle re*? 490 S.G5 Pregtantimag Tool Tht ATUr.yis % OMOOG-I FC3 ?4S5 13® £l 0500®- 1 1 [>.'+. PTRirt jr/m-.ir; 490 itt tJaad Erfrl □= Car Amp r! DJIIKKI'1 F’CS 8-70 >5 75 FUj[thjIh Ugtil Cnnlrcii wim dimmer .1 079337 11 Din rtStsrOsiTwrtes 450 H5 DHJ537-4 1 AT 894305 1 -1 2. 025 11.05 No. 322 JUNE 2003 AVP TV T90MS a ontipo-i pea 0-FQ i^-m rj; 0 SH 2&2 Pvihtatm 8 ESP 15 J5 tj| 83502 6- 1 1 t-iv Art same cafe- 4-M DijQ2B 4 ! AT909S15. tmfartTred wa K90 ttEdrcn-c KnEillEii Kardi.Ercr.iel 3! PaOlua ■ ! 1 EfciiL, PC irtf fd^i^rr ;-dtWi.'n +50 5® 8303^-1 1 A]3£SZ3 '3- IDflZ. po^diTr-a 12M ZSL30 Lnw-Cr-ci UD Guru mitor ^2i 9 rail 4^1 PC 9 0711 15® 1 a 0301 14-11 EM. Cve^ECl 4« iJB3 N.Q3! U-Ij'll Lu'I'jJ ^ 8J&11S-H tei. i& -ifltf taJ; 453 a® O7oi i j 4i tommy iqpc. ™ afmrwj 17® 5275 UfirvErsal KA U=va!d,imerr do 3rd 3 OIQlflM PCS 14S9 23.35 '5 4(01413-1: D>. DAI . M6 SFJHJU r-.e • ^ *ACiV 3.® BIQIM-31 TWig«IC8.^C3S6-9(J r r-^HTTTf: IS4X1 17 70 ElQlOS-23 i3=liOM?CS.2;C7Sa.sa. prop.vrtnri,; 1IH» 17.70 r t'Tii n.i .ii jtai irvs HD 550 N&. 321 MAY 2003 CUunldumi Timsf C. 93C3-35 11 tuto , ji;.! «-,3 r^i r:-n; 490 0&5 020*6-11 *?90512D!LjirEgn’rtniFJ IH0 74.00 L'SH Aijll.c Kocorder ■I1l2fli 3-1 1 Ei». tra«“ ns* tarn 490 5&i 013013:21 [Pfiny pny-Tiv! 12^0 ?T?0 Viili U Final Amp {21 § 429071 -3 FtftiH wort bQ3ivl uiirly no rtiare than □ DVM. TFe comfiod and extremely handy instrument described !n this arti- cle ol-OWi single to quadruple opamps with standord pinning to be tested wilh uncommon oase. Small High End Amplifier Audiophile readers know lhal lots al power does na- equate ft) •Kcelfetit sound — in fact, the opposite is often ir,e case! Our Emafl ■ ,,y-, amplifier is compact and not t oo expensive !q build, y?t achieves superb yjnio quality. The tljnplif cr, designed lo now 'clas- sic' tickler topologies, works happily off Q symmetrical 25 V Theme Plan for 2005 January . Power Supplies February . . -Wireless March .Sound April Mlcrocanlrollws May ...... .Sensors June . . .Erwirotimtui) July/ Augusl .Summer Circuit! September . Test & Measurement October . , .Security November . CAD Software Dwemfev .OpioeJedronics Also.,, tnltoducfipn to l PC? 1 1 * A f?Mee; Anlf 'Sound, Solitaire; USBro-MJDI Convener; Spark Transmitter, Delphi Course fd| PI Cl 6F TlMnptira'uro Logger RESERVE TOUR COPT NOWS flit WotSi 7C-3i isvi-s m sdt wi Friday 15 iMj (UK drisiu^Bi b-t -,1 UK iiiltwriMn, miff rattlYi l?ic me gczjn-e j iV* days teFfli-e thh. dai ?- Ariklt i.ilti cniJ irwgaxi.'ie unluiis sutler i fa ifenga. NEWSAGENTS ORDER FORM SHOP SAVE / HOME DELIVERY PJCflEE Save / deliver one copy r.f EUlklar EfaetmaftM mugaEiiiB !ar me aach month Name: Address : Post code. 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SO Ervsi Enlfimalianal NetLsiihSi CrYaf - tsi . cH*n . ...SO EurnckahtE . 37, ?9 EjpreispCH , .... . .*weipn=*r,finfi t 37 Far«t. ua Linte . , . facd.ca.ub .... ao Fij^uffeS TflcftfnJ*i>tiy DE¥icKi.Hel Lurks BMMdtrifcA^LnH] fltt riflwkt. Net Links . . moth. ttibafaLem w Km ni>nd Ejcr-tfcros. Hot Li*fl ... 1 1 . Id .JaBfabbl, .80 ILF ELsctcr^s Lsnl&il. t»ct Utiks . .......... JO Ips^ Lirv&e JJrtLjrAs . . WnW.^i : fiHJ# 30 ITP WjI V. ■ j-J > 0 ! fftiTJ .43 Jajfcsr LlECttcuucv , . , . hll-,l : ‘= f :r.='-rMcJr,-TC5 WL>k 3 it B f tectwves, fisl tilfti ,\/WV 1 ,V .1 =teJT/X3. r .C* CC?H . . . - . - -.SO KPflicwu, Nn Units 'WJjWTK^llCfrn . . JMt Labcaitur ... . rtV) j ir.Jt]£‘C&L r erre.L , .t . La'rfcm Efectronies Cef-:ja, K5t Units ww'.VJK.Of^.tiPf ®d filllM. Vi. L-n=CiS 1 Ilf . ruMurra t. xxdo. zo j.Jt .43 Miifcrd instrunHiits L 1 ! 1 ) rt.fivfcisi. diLTBiT DC 1 |.r. S3 M 0 F LfciomJr';. f, r *i \ |nJa . , .ir.v,i'ffl,7r=irrm5nTS csj. 1 - ..31 rttt unte S3 31 Ffcw VVavL Cancepls, tir'. 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L ..te ..... cfii’ii at Adnerlising tor the jssufi r,1 1 S Marr,h SM10S may fra reserved nut luter thin IS February 2005 Wrth iEuson Inlrirrptinaal F^erPft - Coiubirdge Ifouse Go-omorc Lane. - Chcrtsey. Surrey KTlG 3AK - hrmlaftn - Fete phone &t932 5 SI - Fn^ 01932 564998 - e-malt: flertvbtarhujanmes^xQm (o- whom all eofiespourfertpe, ;:npy •rt&unrl pus and nrhvorlc sUou'd bf fid ires sc-d 84 r'lUsi tUtfitnisl - 2/^Di p!?aae sup;;v in- folio ini} I'ru FEBs, front panel falls, EPROMs. PALs, BALs. micro :orUrql ana -a-ske"-:^.. sis?? lh,e m I end rtesoriptfonr far honks .-state the fiiir shie- lot phnSflcORtas ol stiicls* statu lulit n p.ei sw ol ait«e!u asid menlli and ytet a I publication. PLEASE USE E LOCK CAPITALS. Description Price each Qty. 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Subsidphsms cannc! be cancel'ed alter ‘tray have fun Eor si* months or mort Jan-jaiy SOtHj Qrttsr now using the Qrrfer Form In Elektor Electronics (Publishing) RO, Dos 190 Tunbridge Wells TN5 7WY ENGLAND Tetephone +44 (0) 15B0 200 657 Rax +44 (0J 1580 200 616 Email: sales@elekLor-elecSrOftios.co.yk the Readers Services section in this issue Gameboy Digital Sampling Oscilloscope a brilliant design EtQ3.no [USS 103 00i CD-ROMS Audio Collection 2 m lj i in-) u= kCIM for me irue audio lover containing no Eewer lhan 75 audio designs Irom the past five year volumes nf elector electronics magazine. The articles on the CD-ROM cover tost & measurement equip- ment, amplifiers, digital audo and , * ti T '~ technology. Highlights include the Mil Ion n urn Edition, Ai._ _ _ _ ADC ^OOG and Ihe 1R-S/PDIF Transmitter and Receiver. Using ihe included Acrobat Reader you are able to browse Ihe articles on your comp user, as well a a print texts, circuit diagrams and PCB layouts. The GBD5G is a plug+n module Jhat [urns Ihe popular Nintendo Gameboy Classic, Pocket Colour dr Advanced into a versatile dual-channel oscilloscope. An oprignal link to a PC even allows measured oscillograms to be viewed or stored on the PC, The GBDSO rocked ihe electronics hobby world and (hat's why we continue ottering ready- built GBDSO mod Nips (including the associated PC software end ihe magazine articles.! More information on www.elektor-e I ectronics~co.uk £12,05 {US$ 21 25) Micro Web Server for Internet and Intranet Robotics A large coffee ti on of date- Sheets, soil ware lools, tips, tricks and internet links in assorted robot construe tmnis and general technical nim rn rA'am i Vi'ji • cJi modern robotics are cover- ed, from sensors la motors. mechanical parts to micro- conlrallers, not iorg citing matching programming iools and libraries for signal processing E12.05 (USS 21.25) ECD tie k tar's Comp □ non ts Database gives you easy actress to design dais ter over 5,700 ICs. more than 35.000 transistors FFTs, thyristors arid sriacs. [ust, under 25,000 diodes and 1 .ooo optcxoLipfers Alt data- bank applrcatians are July interactive, allowing the user to ado edit and complete component data. £12.93 (USS 22.0D) control .and regulation via the Internet Remote measurement and coniral is possible viH Ihe Internet Untertunataly, yj observers usually sil n large, humming grey cabfnels, Thai's r i o I I lie ideal solution lor keeping an eye on your refrigerator. cciJteo machine or central heating system The Flektor Electronics Micro ■'ilfiJfirT-jviwft i.iiuwtiitfs NN tlHiiiiuit I CPU { Models Ca// Wow for Upgrade Pricing Textual library part search. User defined keyboard map, CADCAM output to ZIP file. Bitmap import function* Truetype fonts on RGBs* Enhanced printer output. * Berkeley SP1CE3F5 simulator with custom extensions for true mixed mode and interactive simulation. * 6 virtual instruments and 14 graph based analysis types. ■ 6000 models including TTL, CMOS and PLD digital parts. * Fully compatible with manufacturers' SPICE models. Mixed Mode SPICE Circuit Simulation Schematic & PCB Layout Powerful & flexible schematic capture. Aulo-eomponent placement and rip-up/retry PCB routing. Polygonal gridless ground planes. Libraries of over 8000 schematic and 1000 PCB parts. Bill of materials, DRC reports and much more. Proteus VSM - Co-simulation and debugging for popular Micro -con iroilers Supports PIC, AVR, 8051 . and BASIC STAMP micro-controllers. Go-s Emulate target firmware with your hardware design, Includes interactive peripheral models for LED and LCD displays, switches, keypads, virtual terminal and much, much more. Compatible with popular compilers and assemblers from Microchip, Crownhill, IAR, KeiL and others. SHAPE BASED AOTDROUTER NOW AVAILABLE www. labcenter.co.uk info@labcenter. co. uk