KeInternet modemarts for under £60 ELECTRONICS Denmark DKr. 65.00 Germany DM 15.00 Greece Dra.950 Holland Dfl. 14 Italy L 8000 IR £3.30 Singapore SS12.60 WORLD Spain Pts. 750 USA $4.94 +WIRELESS WORLD A REED BUSINESS PUBLICATION SOR DISTRIBUTION November 1995 £2.10 Isolate RS232 Optoelectronics investigated Mathplus reviewed Transforms in C++ Power and Class -C Linsley -Hood noise reducer Applying the ZR78L05 regulator EW+WW exclusive- ma ineticsensoroffer 9770959 TWO FREE microcontrollers NOW ONLY PSU, parallel cable & data sheets FREE IC extractor ol d ATMEL AT89C2051 - 20 PIN - 8051 derivative - FLASH programmable (1000+ times) - Erase program & verify device in under 5 seconds PIN (1) FAST data ly. transfer - rs connects to PC parallel port (2) Field programmable hardware for FREE future device support (4) MICRO PRO is approved by ATMEL for programming their r.J Ir-J complete range of FLASH micro rs THE FULL EL FLASH MICROCONT L A1111111111111111111 8951 8952 1051 2051 FLASH code ROM 4K 8K 1K 2K 128 256 64 128 I/O 32 32 15 15 Timer/Counter (16 bit) 2 3 1 2 1110UINOX Serial Port YES YES NO YES TECHNOLOGIES 8 5 Interrupt Sources 5 3 At. Pins (DIL/PLCC) 40/44 40/44 20 20 229, Greenmount Lane, Flea Special features Timer 2 Comparator Comparator Lancashire BL1 5JB. UK. Price (1-24 £14-85 £16-95 £4-70 £5-85 Tel: (01204) 492010 Fax: (01204) 494 Int. dialling code (UK (+44 1204) Offer includes one AT89C1051, one AT89C2051 and one IC extractor tool. Offer valid until 31st December 1995 when ordered direct through Equinox Technologies. E-mail: sales@ equintec.demon.co uk All prices shown exclude P&P & VAT plus any bank/credit charges for overseas customers and remain fixed until 31st December 1995. All items subject to availability. Visit our Web page at: For further information on our full range of development systems for the ATMEL microcontroller range www.demon.co.uk/equintec please contact John Marriott at Equinox Technologies. CIRCIE NO. 101 ON REPLY CARD CONTENTS 917 POWER -SAVING 970 REFLECTIONS ON REGULATORS OPTO-ELECTRONICS New regulators designed for Ian Hickman explains how to get the best high-performance and reduced out of opto-electronic emitters/detectors. power consumption. 975 MATHPLUS OR MINUS? 922 INTERNET MODEM Allen Brown looks at a piece of software Joining the net? Phil Collins discusses designed to help teach and learn an intelligent pc modem/fax card capable engineering mathematics. of sustained 57.6kbit/s throughput. 979 TRANSFORMING 930 A NEW DIRECTION IN IN C++ MAGNETIC SENSING Gerard Moloney outlines how he A new three -terminal magnetic sensor developed a C++ library for offers benefits in temperature sensitive performing geometric transforms. Cover - lame! Akib field detection - even down to lOnT. 989 WHAT'S THE Magnetic DIFFERENCE? sensors offer Steve Winder discusses how to EW+WW readers can obtain 20% choose the right differential discount on a new three -terminal amplifier configuration. magnetic sensor capable of detecting down to 10nT. See pages 930 and 933. REGULARS 938 CONTROLLING AUDIO 907 COMMENT DYNAMIC RANGE PhoneDay fiasco John Linsley -Hood's low-thd audio dynamic range controller incorporates a NEWS 908 Audio - John Linsley Hood's expander and switched attenuator. Digital tv, Canada to adopt DAB, compressor is based on a switched attenuator Standards delay video disk, Optical - see page 938. 952 SURROUND SOUND switching advances, GI wants Pace. STANDARDS POLARISE 912 RESEARCH NOTES Peter Willis looks at the pros and cons of Leeches and control technology, two competing surround -sound standards NASA and deep space, Mag-lev, From - Dolby's AC -3 and Europe's MPEG-2. Albert Hall to Albert Terrace, Opto gyroscope for car navigation. 954 ISOLATING RS -232 943 CIRCUIT IDEAS NASA has developed a pilotless, Douglas Clarkson shows how to isolate 20Hz to 250kHz generator, vco, remotely -controlled aircraft RS -232 without involving an mercury -cell replacement, digital powered by the sun - page 913. independent power source. mark:space, programmable switcher, high -input comparator, debouncer. EW+WW 960 DEEPER INTO DC 956 LETTERS READER OFFER ANALYSIS Shifting cultures, Sallen & Key Key Internet modem parts for Owen Bishop looks at dc analysis issues, distortion, hearing -aid plea, under £60. This 14.4kbit/s fax and including component value sweeping and data modem for the pc is capable the pitfalls of simulating oscillators. 983 NEW PRODUCTS of 56kbit/s sustained throughput Pick of the month - classified thanks to error checking and data 964 MAXIMISING POWER for convenience. compression - see pp. 922-926. TRANSFER IN CLASS -C 994 APPLICATIONS Researchers from Ontario present their Power switchers for lcd evidence to disprove a recent statement backlights, Power factor correction for concerning maximum power transfer. power supplies. Next month: Electronics in engine management, New thoughts on distortion, Interfacing GPS. DECEMBER ISSUE - ON SALE 30 NOVEMBER November 1995ELECTRONICS WORLD + WIRELESS WORLD TRANSFORMERS FOR BALANCED LINES IN HIGH Pc! Pruickroute PERFORMANCE AUDIO SYSTEMS Schematic & PCB design for WindoW; 95 and 3.1 '131.9ckFoule 35 ID DEV QRADEMD1 SCHII r -r -r ...-Jrroxeriq TRANSFORMERS 1-7-. 7 71-F7 7F717 7[1, SE F 77F7777777F7777 Ir 40 20 7 E A Sowter Ltd vcc vcc 91.0 ?DOI P0.01 00 30 PO Box 36 IPSWICH IP1 2EL ENGLAND P1.1 A01/ PO.1 D1 01 P1.2 1.021 P02 D2 GI2 P1.3 A031 P0.3 03 33 P1.4 NMI P0.4 04 QA Tel: +44(1)1473 252794 P1.5 A05/ P05 05 35 P1.6 ACV POS P P1.7 1.117 I PO .7 El 2, Fax: +44(1)1473 236188 P3.00 Fia0 AB/ P2.0 P31/ TAD AS/ P2.1 Ooc P32/ I10 .A10/ P2.2 080 llllllllllliF P3.3/ H1 M1) P23 E -Mail: [email protected] P3A/ TO Al2/ P2.4 P3.5 A13,P2 5 AC2 P3.6/ V* A14/ P2.6 P3.7 A15/ P2.7 74573 op..73 6TAL1 UAW-R. TrAl.2 ALEMTh 83T 000 9 Design and Manufacture 080 AO 00 A1 A2 02 2 1C1 33 03 of all types of Audio Transformer using 20 AA DA al Nickel and Grain Oriented cores Free catalogue "moving from schematic to layout could not be easier" review of Quickroute 3.0 in Free technical support service Electronics World & Wireless World Jan 95 Popular types from stock Quickroute, the integrated electronics design solution, available with: CIRCLE NO. 105 ON REPLY CARD Schematic capture, net -list import & export, Gerber file import & export, WMF, DXF, SPICE & PORTABLE PROGRAMMER & EMULATOR SpiceAge export. PROGRAMS EPROMS/FLASH TO 40 INIntegrated auto -routing on 1, 2 or up to 8 layers. PINS WITHOUT ADAPTORS Copper fill for creating regions of copper. EMULATES 8 & 16 BIT Engineering change allows changes on a SYSTEMS schematic to be propogated forward onto a PCB. Prices range from £399.00 down to just £68.00 (prices exclude post&packing, and V.A.T). ,00°' 2M ram, expandable to 8M - avoids multiple downloads and pro- gramming in blocks. Set programming & its an easy touch emulation for 16 bit systems. Tactile membrane for anyone with individual keys Ideal for R&D or small volume production. ISO 9002 for all major functions. manufacture and strict use of manufacturers Supports sector algorithms guarantees reliable programming. protect/ unprotect quickrouteSYSTEMS Limited feature on 29F010/040. 14 Ley Lane, Marple Bridge, Stockport, SK6 5DD. UK. Lloyd Research Ltd. Fast download. 7 & 7a Brook Lane, Warsash, Southampton, 15 seconds for 1M Hampshire S031 9FH, England. bit Intel file. Tel/Fax 0161 449 7101 FREE Tel: +44 (0)1489 574040. email [email protected] Demo Pack Fax: +44 (0)1489 885853. ( IR( LE NO.104 ON REPLY CARD CIRCLE NO. 1060N REPLY CARD 906 ELECTRONICS WORLD+WIRELESS WORLD November 1995 COMMENT PhoneDay fiasco EDITOR Responding to criticisms from BT and Mercury that also refuses to make available numbering allocations Martin Eccles heis accountable to nobody, Don Cruickshank, inside area code groups, except to network operators, 0181 652 3128 director-general of telecomms watchdog agency making it impossible to validate its judgements and OFTEL, has belatedly admitted that his decisions projections or for large users to plan new facilities. EDITORIAL would be better made by a committee and in public. Don Cruickshank's offer to make Oftel more ASSISTANT This dramatic conversion comes too late, however, to accountable is welcome but must be scrutinised. Rob Allcock reverse one of his department's biggest mistakes - this Earlier this year powerful arguments were expressed 0181 652 8638 year's National Code Change. for delaying the introduction of a new national CONSULTANTS Peripheral as this might sound to you, it's not numbering plan but Oftel took the view that "details of Jonathan Campbell because you paid for it. You and other UK phone the new numbering scheme cannot be debated Philip Darrington users shelled out £3,250 million in return for a change indefinitely." Observers contend there was no debate Frank Ogden which did not even solve the most urgent problem - at all and in the absence of an open forum or even a the imminent exhaustion of phone numbers in several situation where all telecomms industry interests are DESIGN & UK cities (cost estimate courtesy of the represented, it is hard to suppress the feeling that Oftel PRODUCTION Telecommunications Managers Association). Despite has not served phone users well in manipulating what Alan Kerr Don Cruickshank's proud boasts on television of new is a scarce national resource. EDITORIAL numbers which would not change again in our lifetime, There are signs that a change of attitude in Oftel will ADMINISTRATION the likelihood is that we shall need new ones well now produce a more effective regime; this is to be Jackie Lowe before the end of the decade - let alone our lifespan.