Electronic-Engineeri

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Semiconductor lasers provide c rrier and optical confinement I The ....a 1 17,13/Artsly innumfflumgmommummulik\ brandnew eaning to ély cost Connector.... effectiveness

Our new 'D' connector is de- Installation couldn't be signed to lower your installed easier; simply insert the cost through exclusive T&B/ cable into the connector Ansley mass termination housing, locate assembly techniques. into standard BLUE MACS TM Utilising our proven insula- tooling, then terminate. tion-displacing TULIP R con- Available at present in 25 tacts in aspread pitch design, and 37 way plug and socket enables this 'D' connector to connector versions, our 'D' be terminated at any point, connector is ideally suited to standard 0.050" pitch flat for both internal and external cable, while at the same time cabinet interconnections by being intermatable with exist- using our standard U.L. listed ing 'D' type connectors. round-conductor flat cable Termination reliability, as or our U.L. listed jacketed with all other BLUE MACS TM flat cable — engineered connectors, is assured by self specifically for external cabi- aligning cable grooves which net use. automatically position the For further information, cable over the TULIP Rcon- circle the enquiry number or tacts. contact us direct. The one-piece connector design with mechanical side latches, maintains the integrity of the connector before, Enquiry no. 171 for the 'D' con- during and after the termina- nector only. tion cycle, eliminating the Enquiry no. 172 for the 'D' con- need for complicated ass- nector and BLUE MACS :rm CablelCon- embly operations. nector System.

pttpm.,01.›. P1. 1.1 1'172 Sedgwick Road, Luton LU4 9DT. Tel: Luton (0582) 597271 Editor Brian J. Jennings Technical Editors Peter Gebler BA Elaine Williams BSc electronic Group Editorial _ Consultant Lord Avebury BA CEng MIMechE MIMC Art Editor Adrian C. Day Circulation Manager engineering H. S. Gibbs Vol 48, no 586 December '1976 Reader Service Manager Grace Wall 4 Comment and Readout: Common Market?; low cost design aid; Marconi opens pcb plant; fibre optic Advertisement Manager Patrick Flynn monitoring; cable plant set up; waveguide trials; development aid for 6800; add on memory; Scopex hails Northern Area Manager successor; support for cosmac; oscilloscope launch; Peter T. VVesthead industry predictions. 061-928 9801 Publisher 17 Applied Ideas: Steam engine whistle simulator circuit; Peter Jago low power cmos switch debouncer; reduction of amplifier offset and drift; current to frequency converter without insulation; complement adders give unambiguous Electronic Engineering is zero output; flip flops help in multiplexing control bits; published monthly and is ram storage adaptor for oscilloscope; hex inverter and or distributed free of charge in the gates for frequency doubler; low power cassette data United Kingdom to designers, recorder; constant speed for apermanent magnet motor; engineers, researchers, technical management, and approved automotive battery voltage indicator for 12 V; programme authorities, in industrial and generates n phase oscillations. scientific establishments 41 Narrowbeam five layer heterostructure lasers: A manufacturing and using variety of (GaAl)AsIGaAs devices have been fabricated electronic components and using two pairs of heterojunctions, G H B Thompson et al, equipment. It is also available to others in the U.K. and overseas explain the characteristics and research undertaken for at an annual subscription rate of these devices. £12.50 (or $37.50 in North and 49 The software challenge for microprocessor South America). Single copy engineers: Microprocessors are likely to become an price is £1.50. essential tool for the electronics engineer. Alan Potton explains how to understand and use them. Notice to overseas readers 59 Design considerations for optically coupled A number of advertisers, at their isolators: In this article Chris Williams describes the own request, do not appear in opto -isolator families and ways of obtaining optimum the world-wide edition. This performance. unavoidably interrupts the page sequence, but does not affect 65 Failure mechanisms in cos/mos integrated circuits: the editorial content. This article discusses the reasons for failure in these circuits. Gallace and Pujol explain how some of these may dWI IG, .0 1976 be avoided, 73 Digital logic board design with test needs in mind: Morgan-Grampian (Publishers) As digital logic ic's become more complex the requirement Limited for testing digital systems becomes more critical, writes Morgan-Grampian House David Tose. 30 Calderwood Street London SE18 6QH 77 Advances in medical electronics: There are several Telephone 01-855 7777 interesting developments in the medical electronics field. Telex 896238 (lndustpres Ldn) The use of lasers and ultrasonics provides both powerful diagnosis and treatment facilities writes Elaine Williams. ABC 89 Product Focus: This month Brian Jennings looks at the This month's cover depicts connectors market, the Amphenol range of Merlin connectors which are 106 New Products used for military, Aerospace 120 New Data and other areas where weight is an especially 126 Classified Advertisements important consideration in design. 128 Advertisers Index 4 on enquiry card 111.111111111111111.11111inina ...... m. immimulumn am mum umummaiummuswe 11111111111.111111111111111111111111111111181110111101.11Mallialin Iii11111111111111•111111111111111111111111.11111ilinnill 111111.1.1111111111111PeRIMINIIIMI0111111111111 a 11111. 11118 1111.1111M111111111111111111111111111111111111311111111111IN 1111111111111011"-L...... , 11111111111111111111111111111111111111111111111111 111111111111111111111111111•111111111111111111111111111111111111111 111111r-41111111111111111111ik— '1111110111111111111111111111111111111111011M 111111 .1111111111.111111111 13M111111111MMIIIIIM1111111.1 1111111111111111111111111113111111111111b.-... . 11111111111111111.11111111111111 Fag 11181. 111111111.11• 11=1.11111.11111111a111111111 0111111111111M11111111111.11111111111i. , 11111111111111111111111111111 II i1111111111111111.111 1111111131111111111111111111 11111111•111111111111M11•111111111._ 11111111111111111111111111111 111111111•11111111111111111 1111111111MMIIMIMIIII111111111111111111111111 L.ill111111311= 111111 11111 III ZIIIIIIRIIIIIZIII BIM 11111111111111 IIIIIIII MI II IIIIIIIIIIIIIIIIIIIIII 0111.1111•11111111111 IMIIIIM MI III II MM. 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The RA200 Test Set quickly Switched attenuators for output gives you accurate traces of audio level and input sensitivity ensure system frequency responses. In just fast and precise evaluation of all audio devices, afew seconds, this self-contained instrument whether having nominally flat response or a clearly displays response as again/frequency steep-cut characteristic. You can adjust the plot on along-persistence CRT. Outputs are sweep rate, set upper and lower limits IL provided for operating an X4 plotter. independently, and use one-shot or repetitive Whether you use the internal sweep oscillator, sweeps triggered electrically or manually. or an external signal, the RA200 requires no synchronisation and adjusts The Wayne Kerr RA200 automatically to the incoming frequency. It covers 20Hz to 200kHz, with resolution down Fast. Accurate. And easy to use. to 0.1dB over avery wide dynamic range. Send for full information today.

WAYNE KERR RA200. 4 Wilmot Breeden Electronics Ferrograph Rendar Wayne Kerr

Please send me information about the Wayne Kerr RA200

Name Position Company Address Telephone Wilmot Breeden Electronics Limited, Durban Road, South Bersted, Bognor Regis, West Sussex. England. Telephone: Bognor Regis 25811 (STD Code 02433). EE 12 /76

2 Electronic Engineering December 1976 5 on enquiry card Type*, cermet- areally exclusive trimmer

Exclusive in apositive sense b ause we make all the component parts, from substrates to adjutjnent shafts, contacts to cermet inks. This enables us to maintain a quality standard you can rely on time and time again.

Type 94 features: * 19 mm (/34 ") long, low profile.* 0.5 watts at 70°C.* resistance range 10 ohms to 2 Megohms. * selection tolerances ±10%.. *temperature coefficients ±100 PPM/°C. *multi-finger brush contact. * panel and board mounting versions. Send for further details of the Allen-Bradley Type 94 now. It's worth paying for quality

U.K. DISTRIBUTORS that pays you. IT.T. Electronic Services. Jermyn Distribution, J. Gledson 8 Company Ltd Newbiggin Lane, Edinburgh Way. Harlow. Essex CM20 2DF. Vestry Estate. Offord Road. Westerhope. Newcastle-upon-Tyne NE5 1PH. Tel: 027-96 26777 Sevenoaks, Kent. Tel: 0732 51174. Tel 0632 860955.

Woolley Components Ltd.. Spenco Electronics (Phoenix) Ltd.. Electronic Component Supplies (Windsor) Ltd.. 214A Manchester Road. Broadheath, 79 Carron Place, Kelvin Industrial Estate. Thames Avenue. Windsor. Berkshire SL4 10P Altrincham, Cheshire W14 5LU. Tel: 061-928 2289. East Kilbride G75 OSD. Tel: 035-52 36311/2/3 Tel: 075-35 68101. or apply direct to: ALLEN-BRADLEY ELECTRONICS LIMITED Bede Industrial Estate, Jarrow, Tyne and Wear NE32 3EN Tel: Jarrow (0632) 897771 Telex: 53353

Electronic Engineering December 1976 3 READOUT Low cost design aid Intel has developed a new 8080 view, the 8080 and the 8085 are design aid known as Prompt 80. almost identical, the 8080 having ee It is offered as alow-cost alterna- only two new instructions. The comment tive to the M DS but can also be pin functions are different, how- used as an M DS peripheral. ever, the 8085 having three levels Prompt 80 contains an 8080 cpu, of priority interrupt and a trap 1 kof ram and amonitor program (non-maskable) interrupt in ad- contained in a 3 k rom. It also dition to the 8080's interrupt contains several seven-segment request pin. It also has a serial displays, a keyboard and a bank I/O facility built in and the 8085's of switches. two additional instructions are Common Market? Two ports are provided at the concerned with the serial I/O front panel, the output ports and interrupt masking. It seems that after a painful recognition that the purely driving led indicators and the Three additional devices com- domestic market is simply incapable of sustaining the bank of switches providing input plete the family; two roms and a UK components industry, the European market place, data. The monitor program will ram. The 8355 is a mask- six times greater than our own, beckons invitingly. support peripherals such as a programmable rom and the 8755 paper tape reader or a tele- is a uv-erasable. Each provides But this invitation is a deceptive one. The obvious typewriter, although neither are 2 k bytes of storage as well as benefits of sheer size and location are dissipated by the required for operation. two 8-bit I/O ports. The 400 ns individual national preferences which disfigure the face An internal prom programmer access time ensures that no wait of co-operation within the EEC itself. This manifests can be used to program an states are required during access. itself particularly in the field of specifications. Britain entire prom or 16-byte segments Both devices contain address of the prom. The system can be latches to interface directly with has failed to impress Europe with domestically inspired expanded up to the full capacity the 8085's multiplexed bus. The specifications which were drafted without reference to of the 8080 using cards from the 8155 ram provides 256 bytes of the needs of Europe. We are now belatedly searching SBC family. As an M DS periphe- data memory and three I/O ports. for that elusive ideal—a framework within which to ral, Prompt 80 can be used as an The ram chip also contains a produce specifications catering for European rather intelligent prom prográmmer or 14-bit interval timer so that the than national requirements. With the continuing delay as a means of allowing several 8085, 8155 and either the 8355 in producing this framework more and more programmers to share the same or 8755 together provide a manufacturers are turning towards US Mil specs, a MDS. complete system with all the Simultaneously with the an- commonly required facilities. tendency which can only hinder the growth of the nouncement of the Prompt 80, The 8085 is about 50%'faster European components industry. Intel has announced details of its than the 8080 and all of the Success here should determine the future of our 8085 family, Intel's immediate devices operate from a single answer to the Z-80 and Motoro- 5 V supply. Like the 8048 and components industry, or indeed dictate whether or not la's improved depletion-mode 8748, Intel's other new micro- it has afuture to enjoy. France, Germany and the rest 6800. The 8085 is essentially a processors, the 8085 is used are equally guilty of vacillation in order to force their faster 8080 with the addition of with 8080's M DS development own national standards on the rest of Europe. The an on-chip clock generator, system so that users of the 8080 appearance of the Industrial Electro -Technical serial I/O and increased interrupt can change to the 8085 without Commission (IEC) and the Committee of European capability. having to buy a new develop- Association of Manufacturers of Passive Components From the software point of ment aid. (CEPEC) is perhaps asign that they are now recognising the need for united action. Marconi opens pcb plant But debates on specifications are protracted within and with the facility to produce print and etch boards. It is the IEC, and some critics claim that, as aforum for designed to produce boards to negotiations at international level it is deficient in BS9760, with high density, tight muscle power. For our part, we must remember that tolerance, fine geometric tracks Europe is no more enamoured of BS9000 than it was of the order of ten thousandths in the beginning, a lack of enthusiasm unfortunately of an inch and narrower, along echoed by many of Britain's own manufacturers. with track spacings and holes subject to equally demanding We must be prepared to abandon BS9000 in the specifications. cause of European harmony. Only by co-operation can The plant is highly automated we ensure the health of the European components Marconi Space and Defence and provides a total in-house industry and shake off our dependance on US Systems has opened a new, capability to produce boards to technology. purpose-built printed circuit full commercial or military speci- board plant in Scotland. The fications and to provide a fast Our domestic electronic components industry has plant is the latest addition to prototype service with a one- suffered much at the hands of interventionalist Marconi's Hillend establishment week turnround to meet the governments, though some of its wounds have been which, since its opening in 1967, needs of Marconi's 'development has grown to occupy an area of engineers. unconsciously self inflicted. It does appear, however, 170,000 square feet and employs Many advanced techniques that the situation which has arisen is because of a some 2000 people. are used in the plant. All pth Government inspired parochialism characterised by a The El m pcb plant has been boards have the plating pattern failure to become a world leader in any one major set up primarily to produce delineated by photomechanical product area. plated through hole (pth) boards, means using dry film resist.

4 electronic Engineering December 1976 READOUT

Fibre optic monitoring Waveguide trials The growth of off-shore oil and fibre optic link, replacing the Millimetric waveguides are the the hydrospace industries has conventional cable. By using a latest developments in the com- generated agrowing requirement fibre optic cable, connectors, munications field. Following field for sophisticated equipment to transmitters, receivers and other trials by the Post Office, the monitor the effects of deep water interface units, the multiplex companies involved with the environments on divers. Hitherto, system enables a diver's physio- PO. BICC and Marconi, in its medical monitoring of divers has logical and life support functions, development are preparing to been restricted to dry simulated such as body temperature, ecg, form a marketing team to sell the conditions but there was a pulse rate, gas temperature, etc system to other countries. requirement as depths increased to be remotely monitored. The 14 km of waveguide to monitor an operational diver. The system enables 16 func- under test at Martlesham can This is particularly so, since the tions to be monitored, each of provide a capacity for half a diver may be unaware of any the input channels being multi- million telephone calls or a mix- deterioration in his physical plexed and encoded to digital ture of data television pictures condition. An operational diver data for transmission through the and facsimile directed through is connected to hie. support single fibre optic data link to the the waveguide along with the system by an umbilical cable and surface control vessel. The data speech circuits. The cable itself consists of a data monitoring must be routed is then decoded and recon- At present conventional cables close wound helix, 50 mm in through this link. The bulk and structed to its original 16 func- can carry 16 000 telephone calls diameter, of superfine enamelled weight of individual electrical tions. The receiver unit offers and even the supercable link copper wire surrounded by an conductors, together with their facilities for computer storage, between planned London and outer wall of glass fibres im- susceptance to electromagnetic outputs for 'scopes, chart re- the Midlands will only have a pregnated with a loaded epoxy interference precludes their use. corders and other display devices capacity of nearly 100 000 calls resin. A layer of aluminium foil ITT and J Er S Marine, in con- and if required, a fibre optic two which is about a fifth of the provides abarrier against oxygen junction with the Admiralty's way voice link can be supplied waveguides present capability. and water and is covered with an Experimental Diving Unit, have which has been made possible The waveguide only requires outer layer of resin and synthetic developed a completely new by extending the voice channel repeaters at a distance of the fabric tape for robustness. system employing a four-core bandwidth. order of 20 km compared with The waveguide is housed in a cables which need signal amplr- steel pipe which is buried at a fication every 2 km. It uses pulse depth of four feet and is capable Cable plant set up code modulation as its system of of following bends quite sharply The first commercial factory to be optical fibre work has been transmission and hence its without any appreciable loss of committed solely to the manu- carried out. suitability for digital information performance. as well as conforming to the BICC who manufacture the '11,Or PO's plan aiming for a complete cable for the waveguide are digital transmission network. confident of the success of the The next step for the develop- systems and have plans to ment of the waveguide is the increase the manufacturing cap- installation of a 123 km run acity of its present production between Bristol and Reading unit at Alperton if the PO but this still awaits final PO approves the Reading to Bristol approval. system. Development aid for 6800 Motorola has officially unveiled its new "Polyvalent" design system, a flexible 6800 development aid that can be used in a variety of configurations. Flexibility is a key feature of the pds, which can be adapted to serve the changing needs of the user as he progresses from evaluation through hardware and software development to facture and marketing of optic STC has already found that the final production. PDS comprises a master board, a video card and fibre has been set up by STC. It is optical communications market a number of options. claimed to be the first unit of its is a substantial one. With the The master board is a single card microcomputer with sufficient kind, operating on a commercial increasing cost of copper and the memory, I/O and interrupt lines to satisfy the requirements of most scale, which will bring together fact that it is a diminishing applications. The card contains the 6800 cpu, 6871A clock genera- all the aspects of optical com- resource, optical cable appears to tor, two 6820 'Dias (providing 32 I/O lines), sockets for 4 k bytes munications under one roof. be an interesting alternative of rom/prom, 384 bytes of ram and both RS232C and current loop Until now optic cable has either apart from its inherent advan- interfaces. Buffered busses allow memory or I/O expansion using been imported from the United tages such as electrical noise the EXORciser's optional cards. The master board can be con- States or produced under labora- immunity and increased capa- verted into an evaluation board by inserting a monitor program into tory conditions. city, since it is made from some one of the rom sockets. The monitor program, known as MIN IBUG Inside the 4000 sq ft factory is of the most common raw II, provides all the standard monitor facilities and allows the board all the equipment required to materials. to be used for developing small programs in hexadecimal code. prepare the silica and pull it into The company sees the cable Editing and assembly facilities can be added if the ram capacity is fibres which are then coated and being exploited not only for extended to 8 k bytes. fabricated into complete optical private and public communica- The video card can be used to convert the master card and monitor fibre cables. Since the unit is tions links and networks but also, firmware into a self-contained development system that does not situated in Harlow it will be easy for usé in aircraft systems, manu- require a teletypewriter. The video card is used to interface the to transfer any developments in facturing plants and other areas master card with acrt monitor or domestic tv set. In addition to the the technology from the research where the size, weight and keyboard and display supplied with such a system, Motorola labs at STL where most of the safety factors are critical. offers a30 cps printer and a cassette interface.

Electronic Engineering December 1976 5 6 on enquiry card NEW AP Range of REED RELAYS TO FIT 14 PIN DIL SPACINGS

This new range of reed relays has pin spacings identical to 14-pin dual-in-line sockets. Less expensive than the conventional dual- in-line types, the range comprises initially 28 types including Form A (normally open) and Form C (changeover) with or without built- in diodes.

CONTACT DATA Standard capsule High voltage capsule Changeover capsule

Max. Power 10W 10W 3W Max. Volts D.C. 100V 500V 28V Max. Volts A.C. 100V 240V 28V Max. Current 0.5A 0.5A 0.24A

COIL DATA Standard capsule High voltage capsule Changeover capsule Coil Volts Coil Resistance

APA/A APA/E APC/E 18 to 30 31(1-2 APA/B APA/F APC/F 12 to 18 1.71aZ APA/C APA/G APC/G 9 to 12 11(1-1 APA/D APA/H APC/H 6 to 9 7000 APA/J APA/T — 5 7000 — — APC/J 5 3200

Please send for further details of this new range ALMA COMPONENTS LIMITED Park Road •Diss •Norfolk •Telephone: DISS 2287 •Telex: 98162

M.O.D. and C.A.A. Approved Inspection.

8 Electronic Engineering December 1976 READOUT Add on Support for COSMAC Industry memory predictions Plessey Memories has intro- The latest survey of the West duced arange of add-on memory systems designed for use with European electronics industry reveals that total production is the ICL 1900 series central processing units. The memories, expected to reach $39 536 million in 1977 compared with designated the Memory Miser, $35 015 million this year. The allows 1900 users to expand the survey carried out by Mackintosh capacity of their present installations by adding additional also shows that during the difficult period in 1975 output blocks of memory, in 16 k incre- increased by only 4% over the ments, up to 65 k words of 25 previous year, which was 10% bits in a single free-standing below its historical mean growth cabinet. rate of 13 to 14% per annum, at The Memory Miser is based on current values. the "P" series of memories In money terms this means which Plessey originally intro- that total production in Europe duced for application in the RCA Service Division has joined bases have been established; rose from $31 239 million in Japanese market over three years forces with RCA Solid State- one at the company's Sunbury- 1974 to $34 068 million in 1975. ago. More than 2000 of these Europe to form RCA Micro- on-Thames headquarters, the This figure is of course inflated units have now been installed. processor System Services. The other in Yorkshire. by an overall 5% devaluation of According to Plessey, the new service provides a con- In the computer field, the RCA European currencies against the system is designed for ease of sultancy and support service for Service Division uses computers US dollar, and the 1974 figure diagnosis, maintenance and re- microprocessors users. made by most of the major manu- compares with values of $39 pair. The cabinet contains the RCA entered the micropro- facturers and employs about 50 billion and $16,4 billion in the memory, logic and interface cessor market early in 1975 with hardware and software engineer- USA and Japan. modules, power supply and the original two-chip COS MAC, ing staff, backed up by several Europe's trading position re- cooling as well as user test now superceded by the CDP- hundred technicians. The divi- vealed it as a net importer of facilities and an on-line spare 1802 single-chip cpu. Since sions activities range from the electronics products with the memory module. then, the company has main- operation and maintenance of rest of the world. Also large trade In the event of a fault, the tained a relatively low profile complete satellite control sys- gaps exist in the areas of com- built-in user-test facility allows while most of its competitors tems and the Ballistic Missile puter systems, video/audio con- diagnosis by an led display. have intensified their micro- Early Warning System at Fyling- sumer goods and in components processor marketing efforts. dales, Yorkshire, to the custom —active, passive and audio. The new service covers all design of microprocessor sys- However, in other sectors of Scopex hails aspects from the initial design tems. the industry West Europe is a concept to manufacture and RCA believes that the new strong net importer with total successor installation, according to the service will result in a much exports of communication, tele- Scopex believes that its new requirements of the customer. It greater share of the market for communications and control and 'scope, the 4D10A, offers the also includes maintenance of the CDP1802 which is still the best specification anywhere in instrumentation equipment existing hardware, a service few only 8-bit cmos microprocessor the low cost oscilloscope mar- reaching $6350 million while existing consultants undertake. available in the British market ket. The instrument has dual imports lagged at $4115 million. Two microprocessor service place. trace operation, a claimed ac- France with its heavy govern- curacy of 3% and is 25% lighter ment support has showed itself in weight. Oscilloscope launch as a net exporter for the first time This 10 MHz version super- in 1975 with totals of $2555 sedes the 4D10 'scope which and its rather more sophisticated million and $2523 million of the company has produced for equipment at the upper end of exports and imports. about four years, but the layout the market which caters for a The only other European of the internal circuitry has specialist field in research and country with a positive trade undergone some considerable development. balance was West Germany. It change. The company manufactures has had one since 1973. The 4D10A costs £150 and about 100 'scopes in the T900 Britain unfortunately did not has stabilised power supplies range per week at its manu- fare so well. The only electronic throughout unlike many low facturing facility in Guernsey but product areas to make a positive cost 'scopes which use un - The latest range of oscilloscopes is looking to increase that to at trade balance was communica- stabilised supplies because of from Tektronix, the T900 range, least 200 per week when the tions and telecommunications the expense involved. The com- is claimed to fill a so far un - market finally established itself, with exports of $311 and $153 pany claims that a 10% varia- exploited market area. The T900 and trends can be assessed. million and imports of $131 and tion in the mains supply will not range in fact has been in the US The company sees two types $89 million respectively. Total affect the trace. and Europe for over a year but of users in the oscilloscopes UK exports amounted to $2370 The attenuator for the instru- Britain was the last international market, those involved in re- million compared with an im- ment has been adopted from the market place for it to be intro- search and development and port figure of $2507 million. 25 MHz 'scope the company duced. those in production, main- Forecasts which have been makes, and allows measure- This was mainly due to the tenance and education. The made for the electronics in- ments up to 50 V/cm. Also, use fact that the company has a latter are more in need of dustry in West Europe for 1980 is made of Glarecheq non- strong foothold in the oscillo- portable instrumentation such as predict that computer systems reflective filters which overcome scope market with its low cost the T900 for which the range was which show the fastest expan- display reflections. range of Telequipment 'scopes principally designed. sion will be 74% up on 1976.

Electronic Engineering December 1976 7 ripivr•P,7w,"- '

7 on enquiry card

Build gour visual dispieu terminal with low-cost deflection packages fr Plessey

Designers of visual display terminals for data readout and point-of-sale applications will welcome the efficient, low-cost deflection packages available from Plessey. These comprise deflection coils, flyback transformers, linearity and width controls, providing high quality resolution for 90 ° and 110° displays. And at avery competitive cost. They are "0 available as individual components too. Plessey has along and extensive experience in the ., development and quantity production of CRT deflection components. Ask us for further information and find out why Plessey wound products are contributing to the prosperity of more and more manufacturers of professional equipment. PLESSEY WINDINGS

Plessey Windings International Headquarters, Fareham, Hampshire, England P014 4QA Telephone: Titchfield (032 94) 43031 Telex: 86214

612 P044

8 Electronic Engineering December 1976 8 on enquiry ce

1 The most complete third generation F.R.A. SM 2001 A has complete harmonic analysis They include facilities for frequency extension, capability, so it's afrequency response analyser in the two channel operation, plotter and computer interfaces. fullest sense. There are also modulator/demodulator and reference Digital techniques ensure high stability, synchroniser units. resolution and accuracy. Frequency range is 0.00001 Hz to 999 Hz (up to It's easy to operate—a fine example of ergonomic 999 kHz with frequency extension). design — apleasure to service—and portable. How's that for an easy to operate, easy to service Yet SM 2001 A costs far, far less than its and cost effective dynamic analysis system. competitors. And arange of custom-built ancillaries Let us send you further details. provides unique flexibility with cost effectiveness. EMI SE Labs

SE LABS (EMI) LIMITED, Spur Road, Feltham, Middlesex TW14 OTD, England. Telephone: 01-890 1477. Telex: 23995. A member of the EMI Group of companies. International leaders in music, electronics and leisure.

Electronic Engineering December 1976 9 / 9 on enquiry card

BARR &STROUD MODULAR

EF3-04 Loy f 4 FILTERING frequency variable from 0-1 Hz to 100kHz Now FOUR Modules- EF3-03 High Pass and more to come! Cut-off frequency variable from 0-1 Hz to 100kHz The introduction of our EF3 Electronic Filter System was abreakthrough in electronic filtering, EF3-02 Low Pass aSystem with options and interchangeability. Cut-off frequency variable from 0-01 Hz to 0kHz Now we introduce two additional modules to extend the scope and versatility of the EF3. To EF3-01 High Pass appreciate fully the technical and economic merits of the EF3 System you ought to have our Cut-off frequency variable from 001 Hz to 10kHz detailed literature which we will be pleased to send. Continuing development of the EF3 System means that we will be announcing yet more modules in the near future. Send now for full details to:

ES A Ft IFt A NI CD

Glasgow and London

Barr & Stroud Limited, 1 Pall Mall East, London SW1Y 5AU. EF3 Basic Main Frame Tel :01-930 1541 Telex: 261877

10 on enquiry card Its not just another XY recorder. It's from Bryans Southern, and one of a line-up of XY recorders with an extra margin of value. So if you're looking for greater performance, precision, features and versatility, you'll find the 29000 series offers more than similar priced recorders. •The 29000 is designed and built to the high standards people have come to expect from Bryans, guaranteeing you outstanding accuracy and along reliable life. You get achoice of A3 or A4 plotting size, with or without built-in timebase for the X axis. You also get aspecification designed to cope with the widest possible range of recording problems. It all adds up to the smoothest operation this side of perpetual motion. Write now for full data. We promise not to send you just another leaflet.

Bryans Southern w Instruments Bryans Southern Instruments Limited, Willow Lane, Mitcham, Surrey CR4 4UL, England. Tel:01-648 5134. Telex: 946097. Grams: Bryans Croydon

10 Electronic Engineering December 1976 11 on enquiry card

' A brighter day for radio broadcasting, with our new high-power tetrode line

From 50 to 500 kW of carrier power from asingle-tube RF final stage. Pyrobloc ® grids plus Hypervapotron ® cooling, for an eye-opening combination of power, compact size, overload safety, light weight, performance and operating reliability! Five different tubes for any high-power short-wave radio broadcasting application, all with the latest and best in power-grid tube technology from aworld leader: THOMSON-CSF.

THOMSON-CSF

THOMSON-CSF ELECTRONIC TUBES LTD /RING WAY HOUSE /BELL ROAD /DANESHILL /BASINGSTOKE RG24 OQG TEL. :(0256) 29155 /TELEX :858865

Electronic Engineering December 1976 11 12 on enquiry card 13 on enquiry card

Burr-Brown's 8-bit ADC82 gives you Electrical a2.8p, see conversion speed, adjustment tree operation, low cost. and much more... Tapes Our new ADC82 successive-approximation AID converter offers both parallel and serial data outputs, output-status signals, and conversion speeds of 2.8µsec are our maximum. It's self-contained, with internal clock, comparator and reference. No gain or offset adjustments are needed for 0 to +10V or -±-10V signal range accuracies of better than -±0.2%, -±ILSB. business All this means money saved in Woven Glass Cloth production and testing. And the ADC82 is Polyester •packaged in ametal (ADC82AM) Woven Acetate Teflon or ceramic (ADC82AG) 24-pin DIP that measures only 36mm by 20mm and is less than 7mm high. ADC82 For details on this or other conversion products, contact Burr-Brown International, Ltd., Permanent House, 17 Exchange Road, Watford W D17 EB, Telephone (0923) 33837 We've got the range A whole family of polyesters, Teflons ... filmic, paper and cloth substrates ... silicone and thermosetting adhesives ... to meet the requirements of electrical specifications. We've got the stock Most tapes listed in the Tuck Range are 'ex stock'. In fact we claim to have one of the widest selections available immediately. We've got the technical resources As part of an international organisation our manufacturing knowhow and technical research is second to no-one. That is why we say that our self-adhesive tape products are all engineered for aspecific purpose to meet given standards of performance. why not make it your business now? Find out more about this interesting complex of tapes for your industry. Write off to:

BUR e BROWN Technical Tape Limited Robley House Orwell Road Kirkdale Liverpool L4 4AB Tel: 051-922 1901 Telex: 627406 Telegrams: Tuckbrands Liverpool London Office: 14 The Broadway Stanmore Middlesex Tel: 01-954 0018 Telex: 934208 Teflon Is atrademark of Dupont Firty-limr eonversion chokes ENGINEERED TAPES FOR INDUSTRY

12 Electronic Engineering December 1976 14 on enquiry card

Our six-sided

box will 321mm reshape your ideas on FFT spectrum analysis

At remarkably low cost, Plessey sPm fast Fourier bio-medical analysis, optical transfer function transform spectrum analysers provide the spectral measurement, signal processing, oceanography, content of analogue or digital input signals of up to education and ECG analysis. 1024 complex points in 237 milliseconds. To an RMS accuracy better than 0.1%. Something special for you? These modular, compact self-contained units offer instant plug-in, black-box simplicity with These SPMs are standard products of our excellent processing performance. sPm-01 transforms highly specialised engineering group based at 1024 complex points in 610 milliseconds; the higher Towcester, developing high performance signal performance sPm-02 achieves this in only 237 processing equipment to meet customer specifications. milliseconds. Can we discuss your special needs? If you think FFT is way out of your reach, think again. OEM quantities of 100 srm-01 in the UK cost €1,700 apiece, depending on specification and design options. One-offs €2,300 each. Neat. Small. Controlled by asimple rrr PLESSEY interface. SPMs can be added-on to mini- or microcomputers, or used as stand-alone modules. MICROSYSTEMS Ideal for production of instrumentation, scientific Plessey Microsystems applications, volume OEM products. They could Water Lane, Towcester transform your ideas, your products and their Northants NN12 7JN perfortnance—in such fields as speech analysis, Telephone: Towcester (0327) 50312 engine health monitoring, geophysics, spectrometry, Telex: 31628 e654 P018

Electronic Engineering December 1976 13 15 on enquiry card Transducer and Recorder amplifiers and systems

-1 -4 -1 -1 -1 .1 .2 .1 .4 .1

differential dc amplifiers •transducer amplifiers •sample & hold amplifiers •operational amplifiers •charge amplifiers •bridge amplifiers galvanometer drivers •bridge conditioning units •thermocouple references •filter amplifiers •V-F & F-V convertors •shaping amplifiers •reliable high performance •protected inputs, outputs and supplies modules individually powered—mains or optional dc supply •housings for single modules and up to 17 in a standard 19" crate •compatible modules for most low & high level signal conditioning

IELECTRONIC 49/51 Fylde Road r 1 LABORATORIES Preston PRI 2XQ I 1 LIMITED Telephone 0772 57560

16 on enquiry card ThenC100010MHZ Timer Counter from Exel. The X LC1000 is a 4 digit counter with facilities for frequency, period, multi period, frequency ratio, time and event measurements, all functions being crystal controlled. Choice of operating mode is by internal plug and socket or exel interconnection of the rear edge connectors, panel cutout size remains constant to facilitate interchange with existing units. BCD outputs are standard and provision is made for the fitting of simple modifications to meet special requirements. OR

FUNCTIONS 1count. Number of periods events. Trigger single or double\ \ Frequency-Sensitivity via 10 to 10 5.Timing units 1µS, line + ve or — ve slope shaper or TTL (d.c.-10MHz). 10µS, 100/IS. selection. Sensitivity via Accuracy—Crystal accuracy + shaper or TTL (d.c.-10MHz). Pulse Width-Positive to 1count. Gate Times—lmS, Prescaling 1-10 7 may be negative edge timing or 10mS, 100mS. Full Scale- applied to this function. negative to positive edge 9.99 MHz, 999.9 KHz, timing. Sensitivity via shaper Frequency Ratio-Sensitivity 99.99 KHz. Gate Times-1S, or TTL fd.c.-10MHz). via shaper or TTL (d.c.- 10S. Full Scale-9.999 KHz, Accuracy—Crystal accuracy 4- 10MHz). Accuracy—Crystal 999.9Hz. 1count. Timing units 1µS to accuracy + 1 count. fl /f2 or Period-Sensitivity via shaper or 10S. f1/12 x N. N=10 to 10 7. TTL (d.c.-10MHz). Accuracy Timing-Clock units 1/IS to One pre-wired plug is normally —Crystal accuracy + 1count. 10S I rom internal oscillator. provided with each X LC1000 Timing units lbfs to 10S. Trigger—single or double line and will be connected for Multi Period-Sensitivity via + ve or — ve slope selection. frequency unless otherwise shaper or TTL Id.c.-10MHz). Counting-Counting external specified. Additional plugs \....Accuracy—Crystal accuracy ± may be ordered if required. r , panel meter people

Exel Electronics Limited, Wolterton Road, Branksome,Poole, Dorset. Tel: Bournemouth (0202) 291430 & 66166

14 Electronic Engineering December 1976 17 on enquiry card This laser diode has infinite application

the fields of communications, high-speed infra- red photography and film marking. Security. Distance measurement. Industrial processing. Defence functions. And, of course, res'earch in the very widest sense. ITT laser diodes are now being manufactured in Paignton — Europe's foremost production centre for laser diodes — after years of research and development by ateam of more than twenty scientists and engineers. They are available in two forms: Single which is why ITT Heterostructure for short pulses of high peak power (about 10 watts), and Double Heterostructùre for comparable mean power but have introduced it. high duty factor. In so many areas of application, you name it, these laser diodes can do it. If you would like to know alot more about these Up to now, the sheer capability of lasers has little lasers, write to: Marketing Department, often been outweighted by the practical ITT Compdnents Group, Electron Device Division, disadvantages of operating them. Now these FREEPOST, Brixham Road, Paignton, gallium arsenide laser diodes by ITT effectively Devon, TG31XJ. overcome all the disadvantages: They're small and light, can be operated on a Name transistor power pack, operate at normal ambient temperature, tolerate extremes of humidity and Address temperature.They are portable, and are ruggedly constructed giving aconsistently reliable Tel performance under really adverse conditions. EE1 2/76 Their uses are as varied as you can imagine, plan or cater for.There are obvious applications in Components ITT

Electronic Engineering December 1976 15 18 on enquiry card The instruments on the left commands for up to 100 sep- £815, the blank plug-in are our good old Models 152 arate tests. Test sequencing EROM cartridge is £1 25; a and 159 programmable func- can be manual as well as custom-programmed plug-in tion generators—the ones automatic. Size of the mem- is £205. But none of these will that are ASCII coded and ory is 1024 eight-bit words. do you any good unless you compatible with the GPIB. You can program the memory have one of our program- And at right is our new supplied with the blank plug- mables. So get one. Model 583 Autoprogrammer, in cartridge, or we can furnish Wavetek Electronics Ltd., 109 Crockharnwell designed to-be used only with you EROMs that are pre- Road, VVooclley, Reading, Berks RG5 3JP our programmables. By means programmed to your specs. Tel: Reading (0734) 694944 Telex: 849301 of its plug-in Memory, the The Módel 583 Auto- Autoprogrammer can store programmer goes for just Y\AÍAVM APPLIED IDEAS

Steam engine whistle simulator circuit

This circuit was designed to making Rt a 470 preset reversed biased base-emmiter the amount of steam in the simulate the whistle of a steam potentiometer and fixing Cl at junction of Tri and the series whistle and can be adjusted if engine in a model train layout. 10 F. Immediately following current limiting resistor, R3. This required. Capacitor C3 deter- A magnet carried by the train the closure of Rs the output resistor should have a value of mines the pitch of the whistle. If momentarily closes the contacts voltage at pin three of the 555 100 K or more. The noise gene- the value of th s component is of the reed switch Rs at the timer IC1 rises to nearly 12 V rated by Tri modulates the increased to 1 F and the steam approach to a tunnel or a level and this energises the whistle square wave of the basic whistle component is switched off a crossing. This initiates the generator circuit based on the tone to produce a shrill wet passable imitation of a diesel whistle for a period determined 741 op amp, IC2. whistle waveform. train is obtained. The circuit and by the time constant provided by The hissing component of the This waveform is amplified by the speaker can be hidden in the R1 and Cl. The time delay steam whistle is produced by the the single stage transistor amp- hills or tunnel workings. required is achieved easily by noise generator comprising the lifier Tr2. Resistor R4 determines M. Plant, Trent Polytechnic.

7 100pF R2 R5 §12k 100k

100k 3 7 8 0,022pF 47k 7 IC1 555 6 cs c C C=7 4 0,47pF II• 0,47pF 8 Tr2 6 0,1pF 100k BC182L* * Rs 4 Reed R8 switch §2k2 10k C6 c== 4,70F T T • • • Time delay Steam whistle Amplifier------

Low power cmos switch debouncer

The conventional cross coupled power and by raising the circuit the flip flop output is used as an cmos gate. Since the circuit has flip flop debouncer has the impedances result in the degra- active load for the switch con- only one input (which is always drawback that pullup resistors dation of noise immunity for tacts. This reduces the steady connected to one supply) the must be used to interface the the open circuit input. state power consumption to that noise immunity is preserved. switch contacts. These consume In the circuit shown in Fig. 2 of the leakage current of the P. G. Hinch, Altrincham.

Electronic Engineering December 1976 17 19 on enquiry card 20 on enquiry card We've Got AWorld oxins clever Of Power vvit In A Small imhof-bedco Relay.

A New PC Board Relay — Optimized for the Best Combination of Size and Performance

Now with this combination we have arelay that offers asignificant advancement in the state of the art. Our RZ relay has aunique symmetrical layout in adual in line package

and 2 changeover single silver: cross-bar contacts which provide switching characteristics of

1,25A; 30W; 50 VA. But with all this the RZ 'all-purpose plastic bpxes relay stands only 11.0 mm above the board.

That's alot of power in a little package. The ITT name on the snap-on cover tells fans you that it is just one more of the many There are over thirty models in our products available from ITT Components' range of highly efficient Frilec fans — all of which can be supplied with a world wide resources. choice of windings to suit your requirements. Special trays are also Our vast, fully automated, global offered, which will accept up to six production facilities offer you the most of these fans, suitable for rack mounting. complete range of electro -mechanical components available on earth.

To find out more about what we can do and. for you, 'phone, write or telex Harlow blowers (0279) 26811, extension 2251, for samples Powerful blowers are also available and specifications. with models suitable for either forced or induced ventilation. Type B13 and B26 (shown here) can have optional Filter State Indicator fitted if desired. ITT Components Group Europe Electro -Mechanical Division, Send to-day for full details. Edinburgh Way, Harlow, Essex CM20 2D E Telex 81146 lmhof-Bedco from Standard Products Limited Ashley Works Ashley Road Components ITT Uxbridge Middlesex UB8 2Sia imhof bedco telephone Uxbridge 37123 wee

18 Electronic Engineering December 1976 APPLIED IDEAS

Reduction of amplifier offset and drift Offset and drift are two parameters that can restrict the use of general purpose amplifiers in low dc analogue signal applications. Expensive chopper amplifiers are often considered necessary to achieve the desired results. As an alternative, a system comprising a general purpose amplifier and fet switches can prove to be a good way of reducing these errors. The output voltage, Vo, is the amplified version of the input signal and is equal to —V oRf/Fl o. This voltage is independent of the amplifier drift and offset. Each sampling cycle is determined by the charging times of the capacitors Cl and C2 and the response time of the amplifier. With 0,11£F capacitors the analogue input can be sampled at regular intervals of 0,5 ms. The switching operation can be split into six time intervals. When SW2, 3 and 6 are closed Cl charges and is fully charged when these are open. The same procedure is observed for C2 with SW1, 5, 6when SW7, 8are closed the total voltage developed is Vo = —AVo. The particular switching sequence explained will reduce voltage errors that may be developed across Cl and C2 due to switching transients. For example, SW3 and SW6 are identical and turn off simultaneously. The charge transferred into Cl by SW3 is practically cancelled by the charge transferred into the same capacitor Cl by SW6.

J. O. M. Jenkins, Siliconix Ltd.

Clock o AB o Clear Clear

Clock input

• SW i

SW 2

«0" SW 3 Tie all J and K to logic

Total logic components DG201 DG201 1 x triple 3 input NAND, 1 x dual

SW 5 SW SW7 S J-K fl ip-fl op 8 g. 3

Electronic Engineering December 1976 19 21 on enquiry card

1=r1 14i7 CLARE AMPHENOL Beswick du6liee GREENPAR ASTRALUX

KVSINITCFI IERC IOR RELAYS MI A MI LB 1111 ELECTRONICS LIMITED Mullard NATIONAL Plessey Interconnect Ltd.

UUUUU BO» man, um maul ".•■• TB MO «BB tf STC ENGINEERED

Poe EtNer Ltd Plessey ITacnfielell Ltd Pye Conneetws Ltd. Poe Dynamos Ltd SIFAM

L47 ASTRALUX

67;;\

4111\ MI La MI ELECTRONICS LIMITED

.1 Ltd.

•hww2,?:;) ri sAsconging

Ringing SASCO at Crawley saves you long-distance phone bills. That single call puts you through direct to 26 top-line component ranges. We'll give you price and availability answers, literally in seconds. Your phone orders will be processed fast ... one major SAS CO customer is saving 50% on his phone bills!

SAS CO PO Box 2000, 61/63 Gatwick Road, Crawley, Sussex RH10 2RU Telex: 87131

SASCO.. THE ON-LINE BROADLINE COMPP lENT DIS TIBUTORS

20 Electronic Engineering December 1976 APPLIED IDEAS

Current to frequency converter without insulation An ordinary current to frequency converter intended for small current requires a switch with a high insulation in the off state. Its leakage current in this state should be lower than the current for conversion. If the current is in the nA region finding such an element is a serious problem. There is a method of over- coming this problem and involves the use of silicon diode based on the principle that the diode has a high resistance at a low voltage.' The same characteristic of the diode is used in the quasi-logarithmic system.' Figure 1 shows the block diagram of a conventional cur- Fig. 1: Ordinary current-to-frequency converter requires switch with high insulation. rent to frequency converter. In the circuit resistor Ra is imma- terial since its value is low Fig. 2: A way to avoid the high insulation switch uses a silicon diode. enough, but switch S should have a small leakage in the off state. To avoid this requirement the circuit has been slightly modified to that of Figure 2. The voltage between the amplifier inputs is very small and the diode has a high resistance. In this way the input current flows into the capacitor only. When the amplifier output becomes higher than a given discrimination voltage the multivibrator starts and acti- vates the switch. The multivibrator must provide a pulse large enough to provide . discharge. After the pulse ends the current flows in the capacitor and the resistor Ra protects the Fig. 3: A practical solution of the small-current-to-frequency converter. amplifier from overload. The minimum value of current which may be converted depends on the input resistance and the diode reverse current. At the present time this may be in the region of pico amps. Figure 3 shows the complete converter circuit. The discrimina- tor uses only one pnp transistor. The multivibrator is explained in an earlier article.' The circuit works up to 10 kHz (10 (IA). With the capacitor at a value of 200 pF and a voltage excursion of 5V the converter produces one pulse per 1 nA. The circuit was experimentally tested with an amplifier composed of afet differential source follower (2N5912 Siliconix) and amplifier 741S. The diode should be carefully chosen. The circuit may be used as a voltage to frequency converter by inserting a resistor at its input.

Dragoljub D. Damljanovic, Beograd, Yugoslavia.

Electronic Engineering December 1976 21 22 on enquiry card

NOW... COUNT 0 co / LATCH DECODE!

Spectra-Tek's NEW 1977 RANGE of DISPLAYS:-

A. Are TTL or CMOS compatible or alternatively will accept pre-decoded information, i.e. 7-wire input.

B. Will Decode, Latch Decode, Count Decode and now also Count Latch Decode.

C. Give '*1 ' in Decode, Latch Decode and 7-wire only.

D. Offer a choice of secondary functions available - e.g. Blanking and Ripple Blanking, or Blanking and Lamp Test, etc., etc. (See new Technical Data Sheet).

The New 1100 and 1600 Series with PCB's in blue punchable laminate look better than ever (though only the engineer sees this!).

All you need is our current Price List and Technical Data Sheet, Part I (Mod. A) and you can order EXACTLY what you need, using the new Code Number.

Digits Heights - 11, 14, 16, 26, 45 and 75mm.

elPECTRA=TEIK VJ IZ< LTD

OUTGANG ROAD PICKERING NORTH YORKSHIRE Y018 7EL ENGLAND Phone PICKERING 107511 72941 Tele> 57725 SPECTR

23 on enquiry card

Glass encapsulated 2 Overload resistance Awell- power); for TV, hi-fi and radio (less known TV manufacturer compared fire risk); for industrial and lA Diodes RAB 219 6makes of similar glass diodes, to automobile electronics (mechanically For immediate delivery find the forward peak destruction strong and sealed against rough The original GE (USA) design, current (lms surge time). Most environments). made under licence by Rifa. failed under 50A. Some reached Nominal current is 1A but many 58, some 68A. RIFA PAB 219 customers use PAB 219 diodes up consistently beat 90A. to 2.5A.Four standard voltages are 3 High peak reverse power available:- rating 1kW, 20iis ,non-repetitive, 200V: PAB 2192 (1N 5059) Glass diodes in general are better half sine-wave! 400V: PAB 2194 (1N 5060) than plastic diodes, with better 4 Low Power Voltage drop is lower 600V: PAB 2196 (1N 5061) performance, longer life, fewer than in conventional glass diodes; 800V: PAB 2198 (1N 5062) breakdowns and hermetic sealing 0.9V for lA compared with the usual Deliveries are good and prices are suitable for tough environments 0.96-0.99V. In abig circuit this 'competitive. Send for full data and for use in potted circuits. adds up. 5 Dip-tinned leads Dip-tinning Rifa AB,S-161 11 Bromma,Sweden. gives superior solderability. Telephone Stockholm (8)26 26 00 RIFA PAB 219 glass diodes are L. M. Ericsson, our biggest customer, Telex 10308.UK Distributors: better than ordinary glass diodes, insists on it, so you get the advantage Adrian Electronics,Winslow, Bucks. for anumber of reasons:- at no extra cost. Telephone (029) 671 3535; 1 Passivation The glass-powder PAB 219 diodes are ideal for Jermyn Distribution, Sevenoaks,Kent. manufacturing process is superior Telecommunications, data Telephone (0752) 50144; to the conventional method using transmission and computer Cartwright Electronics, Glasgow. two separate pieces of glass. peripheral circuits (long life and low Telephone (041) 429 7771.

22 Electronic Engineering December 1976 24 on enquiry card

Linearity

Would you believe oneipartiinno million? Design aDVM of this accuracy, add atrue But we did it with aunique combination of two 0.00011% three month stability —without recalibration — basically different techniques of digitisation. For the and you're liable to create acredibility gap. That's what most significant decades we replaced the conventional happened with our SM 215. resistor network with an inductive divider system. Then For there was no way that conventional design for the remaining decades we employed integrating could achieve this unique spec'. Certainly not in a dual ramp technology. The result—the best of both portable lab instrument capable of operating over awide worlds. Standards room accuracy, while still retaining temperature range. the outstanding noise rejection needed for routine measurements. Now there's MK II —orto give its full title SM 215 MK II Programmable dc Voltage Transfer

IIMIk...111. SY. 1.P. Standard/Digital Voltmeter —the world's most accurate DVM. We can hear you saying — "with aspec' like this who needs aMark II ?" Simply, to provide programmability for the ATE man. And would you believe that SM 215 MK II costs less than many lesser DVM's ?Don't take our word for it. Let us demonstrate just how far ahead of conventional thinking it really is.

EMI SE Labs

SE LABS (EMI) LIMITED, Spur Road, Feltham, Middlesex TW14 OTD, England. Telephone: 01-890 1477. Telex: 23995.

A member of the EMI Group of companies. International leaders in music, electronics and leisure.

Electronic Engineering December 1976 23 25 on enquiry card New portable DMMs. Only Fluke make them only ITTseII them.

New Fluke DMMs Fluke have five measurement functions and introduced two new digital include autozero. The 8030 is a3V2 17Iin this coupon for your copy 7 multimeters. That is big hews in digit instrument with auseful diode the data sheet on the 8030 and itself, because when you are already test facility. The 8040 has 4V2 digits 8040 and send it to: producing the best selling and incorporates autoranging. ITT Instrument Services. instruments on the market, how do The only way to buy Both Edinburgh Way, Harlow, Essex. you bring off another success? these briefcase sized DMMs are The answer has been to take an available from ITT Instrument Name outstanding specification and shrink Services; and from nobody else, not it into atruly portable instrument. even from Fluke. Which brings Company True RMS a.c. This is the most together the best sellers among important feature —especially when portable DMMs and the biggest you realise that it is incorporated name in the instrument distribution in a battery operatedinstrument that business. That means no-delay Address measures less than 6x 5 x 2Y2 in. and telephone ordering, streamlined weighs only 2/12 lb. It means that you internal processing, and delivery can take lab. quality measurement from stock. out in the field, free from the shackles Ask for aspec. sheet now. Or of size, weight and power points. better still, get ITT to arrange ademo. Two versions —8030 & 8040 You will be more amazed by the No Both models offer five rangés over performance than the price! ITT instrument services The only way to buy. Harlow (0279) 29522.

24 Electronic Engineering December 1976 APPLIED IDEAS

Complement adders give unambiguous zero output

It is common practice to enter output. This configuration places soon as the sum outputs are all outputs go to . zero. and display negative numbers in no constraint on the inputs aand equal to one, Ci. goes to one After a propagation delay of sign and amplitude form. How- b so that they may have positive and forces all the sum outputs to tp, C. and Ci5 become one 'ever, in digital circuits it is often and negative values. zero and C. to one. A delay, at keeping the sum outputs at zero. more efficient to handle negative The unwanted zero is removed least equal to the propagation So only the 00000 version of the numbers as a complement since by anding the inputs SO to S3 delay from Ci. to Co has to be zero output is possible. The the hardware for addition and and oring the output of this gate introduced between the and and nine's complement adder can be subtraction remain the same. with C. before feeding into Cin or gates to avoid the or gate constructed in the same way. Two types of complements, as shown by the dotted line. As becoming zero as the sum S. Murugesan, Bangalore, India. true and radix minus one are possible for each number system. They are the one's and two's and, the nine's and ten's complement in binary and decimal systems respectively. In certain applications, despite the slow speed of operation due to an end around carry, one's and nine's complement adders are preferred. However the main drawback is that the circuit is sequential in operation due to feedback from the carry out to the least significant bit. This means that the output depends on the previous input giving two versions of the zero output +0 and —0. This poses a problem for further checking, controlling and arithmetic operation. The unwanted —0 output can be eliminated by the addition of extra gates in the feedback loop of the complement adders. A four bit one's complement adder shown in Fig. 1 uses aconventional binary adder with the carry out bit, C., fedback to the carry in, C. The msb of the two inputs and Ci. are exclusive ored to obtain the msb of the

Flip-flop helps in multiplexing control bits

Sometimes one process may need to be controlled from two panels which are separated by a considerable distance. In such a case a simple select switch will not do since it may be inacces- sible to one of the panels. Instead the multiplexing can be controlled by means of an RS flip flop (see Fig. 1) which can be reset and set from panel 1 and panel 2 respectively (by means of pushbuttons). A simple led display can indicate the state of the flip flop. If the control is to be exercised from more than two panels a circuit discussed in the reference paper can be used with a suitable multiplexer.

A. Mageswaran, Radio Astro- nomy Centre, Tamil Nadu, India.

Reference Elias, Jack: Latch circuits interlock switches electronically. Electronics, January 9, 1975, p. 11.

Electronic Engineering December 1976 25 APPLIED IDEAS

RAM storage adaptor for oscilloscopes Long term monitoring of signal I trains is often necessary in digital Out measurements. To handle this task two types of oscilloscopes 1/2 7473 are used; storage and long 13 persistence types. The prices of 13 both are high and their use Di Mel may sometimes be complicated. 2 The adapter described here ›E-0 Cl IC5 74200 Me2 breaks up the input pulse train We Me3 and stores the result into a ram. J CP 12 D Once the storage capacity of the 14 11 3 1 2 15 7 9 10 11 14 ram is filled the cycle is ended and the repeated waveform of the pulse train is displayed. ,Sync The storage time can be set by out adjusting the time capacitor. 3 2 6 7 3 2 6 7 This period is 252 times longer 4 D 13, than the cycle time of the schmitt DSC-- CD A B e trigger oscillator. A pushbutton 5 25 starts the storage cycle and Cu ICI CY Cu IC2 14 11 ICS1-4 are cleared. On release 11 Cl Cl L —00V of the pushbutton the oscillator OV steps IC1 to the fourth count and 220 74193 6 74193 the oscillator stops. During the first four steps the starting level is ii 2 written into the ram. The storage 9 5 process of the signal train begins 10 8 / 7473 on the effect of its signal transi- .1 113 1/ 2 7473 tion. The output of IC3 changes Time and enables the oscillator which operates the storage process for 2 6 IC5 and the ram. When the 1C3 Cl Cl 1C4 output of the oscillator goes low the ram can be written into and J CP K j cp K as it goes high the counters IC1 220 12 14 1 3 7 5 10 and IC2 step so incrementing OV the ram address. At the end of the cycle (256 counts) further writ- 13 lk lOn our ing is inhibited but the oscillator +5V 2 continues to count and the • -U- ram contents are displayed. 1/4 7435 The sync out line serves for s Start oscilloscope triggering. Resolu- 1/ 7404 +5V 1/ A 74132 tion of the waveform can be In OV improved by increasing the storage capacity of the ram and the circuit can be used for storing more than one train. Deed Tibor, Hungary. \fig. 1

Hex inverter and or gates for frequency doubler

Digital frequency amblers are When delayed pulses are ex- frequently used in many elec- clusively ored with original ones tronic systems. Basically they then two pulses of 120 nsec each require a monostable multivibra- are obtained. tor which is triggered at both The number of inverters in the edges of the square pulse. delay path may be increased or Despite the fact that this tech- decreased as desired. A differ- nique is a successful one, it is ence in the output pulse width is limited by the pre adjusted pulse observed depending on the width which the multivibrator number of inverters employed. provides. This means that there If the number is even then an is an upper limit of operation. output as in Fig. 2a is obtained. This limitation is often lifted by If the number is odd the output the use of afeedback loop which appears as in Figure 2b. complicates the circuit. Stamatios V. Kartalopoulos, A simpler method is in Fig. 1. Toledo University, Ohio 43606.

26 Electronic Engineering December 1976 APPLIED IDEAS

Low power cassette data recorder

A low power 0-500 Hz recorder about 5 kHz for O V input. This and 5 kHz free run via VR2. The PLL are set. The circuit will data may be realised using a means that a ±5V input will output of the 4046 is then fed operate from the cassette voltage cmos phase locked loop and an result in a frequency output of into a 1 kHz low pass filter to supply and may be regulated by LM3900N in conjunction with +5 kHz. Variable resistor VR1 remove the carrier signal. using the zener diode on the any cheap audio cassette. sets the oscillator for 5 kHz with The system accuracy is depen- 4046 chip. The total current The circuit consists of an the input shortcircuited. The dent on the cassettes perfor- drain is between 10-20 mA LM3900N voltage controlled output isthen fed to a4046 cmos mance, wow and flutter and the depending on the load. oscillator which is biased at PLL which is set for OV input accuracy to which the vco and Vernon Boyd, Cambridge.

Electronic Engineering December 1976 27 26 on enquiry card Our microprocessor is masterminding amajor line of microwave ovens. In short order, we can cook up an •appliance control circuit for you, too.

(/ \ There's a revolution simmering Because the time has come for in a microwave oven. With the sweet ,.7 1 the Total Electronic Control. As surely '100 smell of success. We're glad to say, it's E. 0 as it is running out for the electro- the one with our microprocessor in it. DOE mechanical control. Which, in the long -300 Controlling the cooking. The defrost- run, cannot compete. Not in feature- ‘9 1;) ing. Even the time to even out the oriented consumer appliances. Not temperature in between. Controlling when one circuit can carry in it the con- the program and the reset. The display of the time or trol features for a whole line, top to bottom, and be the the timing. one-item basis for awhole inventory. Everything. Right down to the beep. This "no-cost/low-cost" features concept of the Electronically. Total Electronic Control cannot be denied. Not for long. Activated by not even a button, but only Not in the marketplace. atouch. It's the first microwave oven with Total Elec- It's the kind of control, we believe, you will want tronic Control. Which probably makes it the most in your home appliances. For it's the kind of control, we sophisticated kitchen appliance in the world today. believe, the consumer will have in hers. And it's only a matter of time before other appliances follow the lead.

We help you compete.

GENERAL INSTRUMENT MICROELECTRONICS LTD 57-61.Mortimer Street, London.W1N 7TD England. Telephone: 01-636 2022 El Telex: 23272

28 Electronic Engineering December 1976 APPLIED IDEAS

Constant speed for a permanent magnet motor

In any applications where per- lised by the circuit shown. manent magnets are used it At point A would be useful to maintain a Ea = la(RaR1)-1-Va-I-Vbe (1) constant speed under avariety of 11 — laR1/R2 (2) loads. Consider the speed equa- 11 = Vs/R3A-E a/R4 (3) tion for such a machine Equations 1and 2 into 3 results in Va = la(R1(R4/R2 —1) — Ra) Ea — Rala V — —VsR4/r3 —Vbe K To compensate for Ra, It can be seen that to achieve Ra = (R4/R2-1)R1. aspeed V which is constant and Thus from Vs<0 and VsR4/ directly proportional to the ap- R3>Vbe: Va = VsR4/R3. plied voltage Ea the term Rala Also R2 should be very much must go to zero. This can be greater than R1. accomplished by the introduc- Thus if the dc value of Ra is tion of aterm —R which is equal measured and R1, R2 and R3 in magnitude to the armature are selected to compensate, the resistance Ra. The speed equa- resulting armature voltage will tion then becomes: be constant and consequently the speed will be constant. A Ea—(R a—R)la V — variety of circuits of this form K may be realised to use both dual and with R = Ra, V = Ea/K and single power supplies. This cancellation can be rea- R. McGillivray, Toronto.

Automotive battery voltage indicator for 12 volts An indication of battery voltage voltage over the critical range led1 and led2 are lit while at diodes or extended by adding is useful to the motorist in many 10 to 14 V. 12 V Tr2 is on, led2 has reached alternating polarity versions of ways such as monitoring the When the voltage is less than its full brightness while Tri is off Tr3 and Tr4. battery's capacity to deliver 10 V transistors Tr2, Tr3 and Tr4 so turning led1 off. Similarly led3 P. H. Boyce, Swindon, Wilts. current and as a check on the are off and Tri is turned on with is turned on by Tr4 as the voltage efficiency of the dynamo and a base current via R2, R3 and rises to 14V and Z2 conducts. Red Yellow Green Voltage regulator. The circuit described led2 illuminating led1. As the Tr3 takes current away from led2 1 0 0 <10V is a solid state alternative to a voltage rises above 10V the and turns it off by shorting it out 1 1 0 11 V moving coil meter. Table 1 Zener diode Z1 begins to con- while Tr2 remains in conduction O 1 0 12 V shows the output which uses duct, Tr2 receives its base cur- to keep led1 off. The circuit can O 1 1 13 V three different colour leds to rent via R4 and turns Tri off. be easily modified for different O 0 1 >14 V give an indication of the battery At approximately 11 V both voltages by changing zener

Electronic Engineering December 1976 28 27 on enquiry card Looking for performance, reliability and price in miniature plug-in relays?

We are one of the largest manufacturers the electronics world. Each is built to uncoMpromising of miniature plug-in relays in Europe. quality standards. . with ultrasonic The Miniaturised Bi-stable polarised cleaning throughout coupled with relay type VPR and the P.O. approved exacting performance and timing relay type 23 are but two from a checks. range used and approved throughout

Oliver Pell Control Ltd., The same goes for Cambridge Row, Burrage Road, London SE18 7JN. our AC range. Tel: 01-854 1422 Telex :897071 Name These miniature plug-in relays have the same physical dimensions as the DC range. Company' Shown: 2and 4-contact versions. For all the help you need, contact Address Varley Technicians now or send for the catalogue. EE19/76

30 Electronic Engineering December 1976 APPLIED IDEAS Programme generates N phase oscillations Consider first the generation of due to the finite word-length smaller the error, which is sinu- natural extension of the approxi- a 2-phase waveform by micro- used for the factors sin 5° and soidal with a period of 1/w mation (5) and (6) to a3-phase processor. Initial values of say cos 5°. But because of this no cycles. Modulation in amplitude system where the three phases sin = 0 and cos = 1 are first reduction in amplitude occurs is performed by the addition of A, B and C are 120° apart. set in. Then the sum of two over any number of cycles if the aconstant kthus, sin (n+ = One cycle of oscillation is angles formulae: following approximation is used. sin n+ 0. cos n+k - tabulated in Table 2 where, for sin (n+ co) = sin n. cos w Consider that: cos (n+ cos n- (o. sin n ease of working co = 0,4 (=39 °). +sin co. cos n (1) as w tends to zero, cos w tends The amplitude is increased in Figure 2 shows the actual cos (n+ co) = cos n. cos w to 1 (3) the ratio 1+k/. If the omega results to a graph plotter for a -sin ca. sin n (2) as Ci, tends to zero, sin w tends factor differs for sin and cosine 5-phase system. The program is is repeatedly performed. Here n to w (4) then the number of steps per shown in Table 3. Here w is the current values and w In (4), co is in radians, for ex- = 0,04. For 5-phase each phase cycle is 27r/V. is the step size. If co is to be 5° ample, if w = 1° then is 360/5 = 72° apart. Therefore Phase modulation can be then the (n+1)th sine and sin 1° = 0,017452 initial values were A = 0, B = performed by computing, cosine values are Finally, substituting (3) and (4) sin 72°, C = sin 144'; D = sin sin (n+1) = (sin n) (0,99) into (1) gives, sin (n+ co) = A.sin n+ co. cos n 216'; E = sin 288°. cos (n+ G.)) = (1/A).cos n +(0,087) cos n sin (n+ co) = sin n+ w. cos n However, in a 3-phase system - w.sin n cos (n+1) = (cos n) (0,99) (5) the number of steps per cycle is -(0,087) sin n For the cosine, substituting (3) Where A = 1+ w.sin e and found to be 27,W3/ Such a procedure will result and (4) into (2), gives, O= the required phase change. N. Darwood, Feltham, Middx. in a sinusoidal sequence of cos (n+ co) = cos n- w. sin n The last is demonstrated in Table values where, if an analogue (6) 1for aphase change (0) of 40°, Table 3. 5-phase approximation waveform is required a digital Where w is the step-size. with w = 0,5 radians (= 28,6'). and analogue converter is used. Approximation (5) and (6) From which A = 1,32. Fig. 1 is A = A+ w(B-C+D-E) But the system is not useful when continuously repeated pro- aplot of Table 1. B = B+ w(C-D+E-A) as the maximum amplitude duce a sine-wave sequence of Such sequences of sinusoidal C = C+ c.)(D -E+A-B) attained per cycle diminishes values with a period of 27c/co values are an ideal medium for D = D+ co(E-A+B-C) finally to zero. This is entirely steps. The smaller is ca the waveform synthesis and it is a E = E+ w(A-B+C-D) •

Table 1Phase change of 40° with co = 0,5 radians Table 2 STEP SIN = COS = A = A+0,4(B-C) A sin n+0-5 .cos n (11A) cos -0.5 .sin n STEP B = B+0,4(C-A) O 0 100,0 C = C+0,4(A-B) e-- 0+ 50 = 50 75,7-25 = 50,7 A = 0 66+ 25 = 91 38 -45 = -7 0 B = 100 } INITIAL VALUES 120+ -4 = 116 -5 -58 = -63 C = -100

153+-31 = 121 -108 In A = 0+0,4( 100+100) = 80 103 -133 CO 1 B = 100+0,4(-100- 80) = 28

ETC 69 -135 h C = -100+0,4( 80- 28) = -79

23 -114 COMO., -26 . -73 A = 80+0,4( 28+ 79) =- 123 -71 -19 2 B = 28+0,4( -79-123) = -53 -103 37 C = -79+0,4( 123+ 53) = -9 -117 87 A = 123+0,4( -53+ 9) = 105 N -110 121 3 B = -53+0,4( -9-105) = -98 (,) -84 134 C = -9+0,4( 105+ 98) = 72 szt -44 123 LO A = 105+0,4( -98- 72) = 37 91 -40 4 B = -98+0,4( 72- 37) = -84 C = 72+0,4( 37+ 84) = 120 A = 37+0,4( -84-120) = -44 5 B = -84+0,4( 120+ 44) = 18 C = 120+0,4( -44- 18) = 95

Electronic Engineering December 1976 31 n ,

Nuplial ilaNs lurnuatifinlE13

Prizes in the 1976 Applied nating establishment. A Ideas competition will have contributor's fee of £10 a total value of £1000. will be paid on publication. This is the third annual Applied Ideas must be Applied Ideas competition, typed, using only one side and this year's joint sponsor of the paper, with double is the Reading-based com- electronic spacing and wide margins. ponents distributor Celdis. Illustrations must be drawn Prizes will again be awar- clearly on separate sheets. ded for the best Applied They should be captioned, Ideas published in Elec- engineering show component values tronic Engineering during and type numbers, and the year. Originality, suita- indicate test voltages and bility, elegance, adaptability waveforms where appro- and general usefulness will priate. Entries should con- be taken into account. form to the usual style of Contributions should give the journal. a full but concise account Please send entries to the of purpose, along with de- Applied Ideas editor, Elec- sign criteria and an indi- tronic Engineering, Morgan- cation of performance. Grampian House, 30 Cal- Entries must be from derwood Street, London named individuals and must CELDIS SE18 6QH. not have appeared pre- The Editor's decision in viously outside the origi- all matters is final.

28 on enquiry card

HEMITIER QUALITY. PERFORMANCE RELIABILITY' SERVICE COMERS APPLICATION ADVICE' COMPLETE RANGE HEAGSTIER HEnGSTIER lawmen TYPE 841 •uii l'(„) Hub, HMI HEfl HEW FEATURING TYPE 422 6 digit predetermining HEIllenica counter with electrical reset. Shown are just afew examples from our large range of counters. HENGSTLER HEnGnitai Hengstler GB Limited, Nazeing New Road, Broxbourne, Herts, EN10 6SX HEÉIGSTIER Tel: Hoddesdon 68451 Telex: London 263243

32 Electronic Engineering December 1976 437grr - e 29 on enquiry card YOUR OWN LABELS HOUSE,111 MINUTES WITH 3M SCOTCHCAL PHOTOLABEL SYSTEM Et. DO All you need is ecise an ultra-violet. Perfect reproduction ligtit source of simple or complex and a 3¡\11 one- images from any step developer. y artwork.black on translucent No training needed.

WARNING: Identification tags, instruction panels, warning plaques, re. `-r -71"."." .1.100. Eye Protection nameplates, instrument dial faces, • e ; SA LflST

required circuit diagrams, badges etc. 'et

e 0 TERMINAL BLOCK A 0 0

OFF 4 J.WOOLYARDS Manager

r- COLOURFUL Achoice of colour To D.Graddon. Decorative Products Grou7,1 combinations for maximum eye- Complete the coupon for your 3M United Kingdom Limited, FREEPOST 18 appeal and visibility. FREE London WlE lYZ. Ishould like to know TOUGH Indefinite indoor life. more about your Photolabel System. DEMONSTRATION Please arrange afree demonstration. 1-3 years outdoor life. or for your III Please send me your introductory kit. SELF-ADHESIVE No screws to INTRODUCTORY Ienclose cheque/PO for £3, made fix, no holes to drill. payable to 3M United Kingdom Limited. KIT EJ Please send further literature. ECONOMICAL Labels cost about NAME 2/12 pper square inch. £3 INTRODUCTORY KIT QUICK Easy, three stage process TITLE If you prefer, send £3 with the takes 5-15 minutes. No darkroom, COMPANY coupon for acomplete introductory no waiting for outsiders. INDUSTRY kit. All you need is an ultra-violet FREE DEMONSTRATION light source.Your £3 kit contains ADDRESS Return coupon to arrange afree everything else for your first set demonstration on your premises. of photolabels. (Sorry, only one And discover for yourself why EE 12/76 kit per person.) TEL. NO. corporations like British Rail, BAC 3M UNITED KINGDOM LIMITED and the RAF are making their marks Regd. Office: 3M House, Wigmore Street. London W1A IET Eire Telephone Dublin 851555 L_Photolabel with 'Scotchcal' Photolabels from 3M. 3M and Scotchcal are trade marks. Regd. No: 241888 3,

Electronic Engineering December 1976 32A 30 on enquiry card 31 on enquiry card

IEMILM3UgGEMIMI THE CRIMPING TOOLS THAT KEEP IN STEP WITH CONNECTOR MINIATURISATION 1

Thinking Economic Tape Readers? Think Data Precision FER 201

Although priced at only £185.00 with generous quantity discounts, the Data Precision FER201 operates up to 250 characters/second and is bi-directional. Total control and interface logic is mounted on a single card while a stepping motor, mounted directly onto the back of the read head helps to keep the design simple and the device exceptionally silent in operation. The Microcrimp Tool crimps even the smallest No preventive maintenance is necessary. contacts All 5 and 8 track tapes to ECMA and DIN standards etc. and a transparency up to 70% for infra-red are accept- Deals with solid and stranded conductors able. Infinitely adjustable crimping depth with direct The reader can be supplied is acomplete unit for customer mounting into their own panels or with 19" rack, tape reading indicator • spooling or fanfold cassette. Ratchet control ,Can be locked after setting DaTHINtK a Precision For this and other too sto cover all your crimping needs write to

Data Precision (Equipment) Ltd 81 Goldsworth Road, Woking, Surrey GU21 1LJ ERMA LIMITED Telephone: Woking (04862) 67420 St 64444 Mount Pleasant, Alperton, Wembley, Middlesex NORTHERN SALES OFFICE 1Telephoneel) 903-4561 Telex 264229 98 Kenworthy Lane, Manchester M22 4B E Telephone: Wythenshawe (061-998) 2612

32B Electronic Engineering December 1976 32 on enquiry card

Currently travelling at twice the speed of sound

You'll find Hellermann Insuloid Hellermann Insuloid is a insulated cable clips and clamps, products travelling supersonically division of the Bowthorpe-Hellermann flexible trunking hose clips, terminal on the Concorde,keepi ng wiring Group-established leaders in'Cable shrouds, harness breakouts and harnessed safely, efficiently and Care The company manufactures bus bar insulation. Everything in permanently. acomplete and diverse range of fact, that you need to fix, hang Hellermann Insuloid products are cable tie harnessing systems and secure, label or protect wire and used at the frontiers of technology accessories includin Insulok cable cables. as well as in down-to-earth ties, cable saddles, bridge saddles, All products are designed toM0A, applications, like washing machines, ARB and US military specifications telephone exchanges, hi-fi sets, and are backed by acomplete design underground trains-anywhere you and application service. have cables that need fixing If you have acable harnessing securing hanging identifying or problem-move fast. Contact protecting. Hellermann Insuloid today. Hellermann Insuloid Wythenshawe,Manchester M22 4RH Tel: 061-998 5415/6/7. Telex: 667657

lbe .THE BOWTHORPE-HELLERMANN GROUP CONNECTIONS THROUGHOUT THE WORLD Hellermann Deutsch •Hellermann Electronic Components •Hellermann Electric •Hellermann Insuloid •Bowthorpe-EMP •Bowthorpe-Hellermann Distributors Power Development Ltd •Hellermann Cassettes Ltd •Hiatt & Co. Ltd OThe Bowthorpe-Hellermann Group,Catwick Road,Crawley, West Sussex.

Electronic Engineering December 1976 32C 33 on enquiry card 34 on enquiry card Temperature Sensing?

PKITILM PLATINUM RESISTANCE TEMPERATURE DETECTORS

*Resistance 100 ± 0,1u *BS1904 Grade II (BIN43760) *Temperature range -50 to +500°C *Alumina body *Available ex stock *One size for single and double detector units

MEET 90% OF APPLICATIONS Mir 20% LESS COST VERY COMPETITIVE PRICES!

PF41 Single unit £2.60 each +VAT Minimum order *50 units

PF42 Double unit £4.30 each +VAT Minimum order *30 units

*Larger quantities in multiple's of 10

Trim point // Leads 0.320

You can have them virtually 32 any way you want them. Dimensions Models PF41 and PF42 Spirals.Tubulars. Hexagonals. Mica-cards. From 12W-31(W. FREE SAMPLE! Single or ganged. For free sample of Model PF41 just phone You name it-we'll supply it. or write (company letterhead, please)

Claude Lyons Controls Ltd Ware Road, Hoddesdon, Herts. EN11 9DX. Tel: Hoddesdon 67161 Telex: 22724 Rosemount Leaders in resistance thermometry

Rosemount Engineering Company Lirniled Durban Road -Bognor Regis-Sussex P022 9QX Tel: Bognor Regis (0243313121

Electronic Engineering December 1976 35 on enquiry card

.... and buy the best performance at the lowest cost

1057: The latest from Datron

The Datron 1057 is a digital multimeter which combines the high performance of a sophisticated DVM and the low cost of a conventional multimeter. This has been achieved by making use of the unique circuitry developed by Datron for the company's range of Premium DVMs and applying the benefits of their volume production. The result is an instrument with a performance only slightly below that of the most advanced DVMs — but at less than half the price.

Who else can offer: * 199,999 full scale * DC and True RMS AC volts * 1AV resolution * DC accuracy 0.015%R for a full 6 months * 10 mOhm — 10 Megohm resistance measurement * Fully floating guarded input * 1000 V overload protection * 2 year comprehensive warranty ciatrost * Ex stock availability from ITT instrument services The only wholly British-Owned manufacturers of Premium DVMs

Datron Electronics Ltd •Meteor Close •Norwich Airport Industrial Estate •Norwich Tel (0603) 412126.78 Telex 975173

Electronic Engineering December .1976 33 36 on enquiry card New from Gould Advance. 50MHz you can get carried awa with.

The Gould Advance 08330013 high quality laboratory work. The price will make you gives you 50M Hz bandwidth And the details are appro- lighthearted. with 5mV/cm sensitivity, '1 mV priately mobile. Dual delayed And we recommend you to 10MHz. timebases with mixed sweep, ask for data by using our Which you can get up and trace location and uncal lamps enquiry number. go with since it weighs only help ensure it. We'll get it to you faster than 28Ibs. As do the bright CRT-13kV you can say 'Gould Advance Worth heavy consideration EHT and fast timebase speeds - have produced abetter scope. are the wide range of applica- 1Ons/cm, fastest. Again!' tions for general purpose and 1781

Gould Advance Limited Roebuck Road, Hainault, Essex IG6 3UE, England. GOULD ADVANCE Telephone: 01-500 1000 Telex: 263785

34 Electronic Engineering December 1976 F: -.Y=e - 37 on enquiry card It's the end of the line for old 8-bit thinking and planning. The Teaming up with the 9900 TMS 9900 has won the day with an unbeatable display of power The 9900 doesn't ride alone. The family will soon include: • and efficiency -opening up the big, new country of 16-bit SBP 9900 -I 2L implementation of the TMS 9900 for microprocessor hardware. Ride off into the sunset with military applications, with an operating the 9900 family and the Magnificent 16-bit. temperature range of -55°C to +125°C. TMS 9980 -a 9900 with the data bus multiplexed to fit into alow cost 40 pin package and still This is the score retaining the full instruction set. TMS 99XX- amicrocomputer for high volume low cost The TMS 9900 and 990 family of minicomputers are opening up new territory in architecture, software support and applications, using asub-set of the TMS 9900 instructions. instruction power. The designer with 9900-based product is now way ahead of others using 8-bit microprocessors both in SN54 S481 -a 4-bit slice arithmetic element, micro- performance and design cost. The 9900 is a16-bit microprocessor programmable to emulate the 9900 or any other instruction set. with Memory to Memory architecture giving complete programming flexibility. The powerful instruction set includes The Good Guys ride together hardware Multiply and Divide. It's quick on the draw with 16 x16-bit Multiply in 17.3 microseconds. The whole team are Software Compatible -not only with each And there's more support on the way: other, but with the TI 990 range of minicomputers too. Ride into TMS 9901 -a programmable interrupt and I/0 controller. the1980's with the good guys -8-bit is dead, long live the TMS 9902/3 -asynchronous/synchronous communication Magnificent 16. controllers. TIM 9904 -a four phase clock generator. Write or 'phone now for full information to TEXAS INSTRUMENTS LIMITED Microprocessor Centre (MS15), Manton Lane, Bedford MK417PA. Telephone 0234 67466.

The Magnificent 16. •••:.*: •

j. •:•-:.¡:•••

Electronic Engineering December 1976 35 38 on enquiry card We measure up to your standards

Whether you check components at Goods Inwards, during production B900 or on Final Test, Wayne Kerr has the Automatic Digital Bridge 1kHz 0.1% bridge you need. For fast measurements of resistance, capacitance and inductance, or for continuous monitoring of changing values, you can select the ideal instrument from our comprehensive range. All models—AF, RF and VHF— have awide measurement range and are easy to use. Many have automatic B224 readout and automatic lead Wide-range Audio Bridge 1592Hz compensation; most will measure (200Hz-20kHz external) components in situ. Only part of our range is illustrated. Send in the coupon for further information.

4 Wilmot Breeden Electronics r Ferrograph Rendar Wayne Kerr

Wilmot Breeden Electronics Limited, Durban Road, South Bersted, Bognor B331 Regis, West Sussex, England. • Self-balancing 0.01% Precision Bridge Telephone: Bognor Regis 25811 (STD code 02433)

B642 Autobalance Universal Bridge 0.1%

Please send me the Wayne Kerr short form catalogue.

Name

Position Company IAddress

Telephone EE12/ 76 I Wilmot Breeden B421 Electronics Limited, Direct-reading Component Meter 0.25% Durban Road, South Bersted, Bognor Regis, West Sussex, England. Telephone: Bognor Regis 25811 WAYNE KERR BRIDGES (STD code 02433)

36 Electronic Engineering December 1976 39 on enquiry card

One lump ahead.

Almost overnight Westcode put its house VITAL STATISTICS OF THE R220 THYRISTOR in order. Look at them closely and Now we've gone one step further. We don't just you will begin to get ideas.. provide acompetitive service —we're one jump design ideas to put you one ahead in processing of orders, availability of stocks, jump ahead. Consider the speed of delivery. R220's balanced dynamic Hang on tight ... we could be the world's first performance for both H.F. supersonic kangaroo! and switching duties:- 2000A peak sine wave current at 5KHz plus voltages to 1200V and repetitive dI /dt ratings to 1,000 A/ps. INESTCODE Consider how this increased output per device Westcocle Is aregistered trademark of Westinghouse Brake & Signal Co Ltd can save auxiliary circuitry for snubbers, firing circuits Semiconductor Division, Westinghouse Brake & etc., reducing components and increasing equipment Signal Co. Ltd., C-hippnham, Wilts SN151JD. reliability.Send for the data sheet —use the reader Tel: Chippenham (0249) —4141. Telex: 44751. reply service for your copy.

UK STOCKIST DISTRIBUTORS:Consort Power Sales Ltd„ Rosebank Parade, Yateley, Surrey. (0252) 874075. Telex: 858809; Semicomps Northern Ltd., Kelso, Scotland. Kelso 2366. Telex: 72692; G.D.S. (Sales) Ltd., Slough, Berks. (0753) 30211. Telex: 847571; Harmsworth Townley & Co. Ltd., Todmorden, Lancs. 070-681 2601.

Electronic Engineering December 1976 37 40 on enquiry card

Quite simply, the Maestro is the finest voltmeter in the world. A masterpiece in measurement technology.

It's the.product that gives you more than any other on the market. Like unique Decastat display; seven 9's scale plus over-range; one pprn linearity; 200 readings/s and fast auto-range.

The new Maestro gives one in 14 million ...by any definition, resolution. It knows the answer toinV, it gives a result to 10nV in systems, and the display is rounded the master in the art of to 1pV digital voltmeter The Maestro cannot lie — not with abuilt-in self-check facility. And all its features are controlled technology by remote programming. Features like 70dB series modé rejection, 144dB common mode rejection. A choice of five speeds, scale lengths and I Niviq..r•iner vq.) resolutions. And digital filtering for fast settling kit \ni•u without dielectric storage effects. Vor.p:. I

Truth in the specmanship. game is important. Solartron don't play specmanship. The Maestro — or 7075 if you prefer type number designations — is backed by Solartron's Standards Laboratory where the Volt is known within 1pV of the National Physical Laboratory.

With aproduct like the Maestro we can't help banging the big drum. Find out more about it. Contact us direct, or fill in the magazine's reader reply card. The Maestro's specification will be sweet music to your ears.

38 Electronic Engineering December 1976 41 on enquiry card

11/11/1111/. IMP

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Electronic Engineering December 1976 39 42 on enquiry card McMurdo focus on five

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40 Electronic Engineering December 1976 - fIV•elre. , I

Narrow beam five layer heterostructure lasers

A variety of (GaAI) As/GaAs heterostructure lasers have been fabricated with two pairs of heterojunctions, the inner pair for carrier confinement and the outer pair for optical confinement writes G H 13 Thompson, G D Henshall, J E A Whiteway and P A Kirkby.

Heterojunctions of (GaAl)As/GaAs are enough to give satisfactory carrier con- The outer heterojunctions of the five- used in semiconductor lasers to provide finements without any contribution from layer structure are relied upon to control carrier and optical confinement. This the outer heterojunctions. This becomes carrier leakage. Minority carriers spread dual function is possible because sub- more demanding for narrow active layers throughout the resonator and their stitution of Al for Ga in GaAs increases and for high-threshold current density. recombination rate in layers adjacent to the band gap and lowers the refractive Also, the active layer should be narrow the active layer must be limited. index. Structures with two pairs of enough to avoid perturbing the optical The multilayer heterostructure devices heterojunctions, the inner pair for carrier distribution excessively. This becomes reported up to the present in litera- and the outer for optical .confinement, more demanding as the composition ture have used 10-12% AlAs steps or exhibit versatile characteristics. steps increase. These apparently con- simply p-n junctions to confine carriers. A localized gain region (lgr) is created flicting requirements can in theory be In this article five-layer devices are by sandwiching the lowest-band-gap reconciled by making the active layer discussed where 20-25% carrier con- active layer between two oppositely very narrow (cg, <300A) and using rela- finement steps are used and where the doped passive layers of intermediate tively large composition steps at the structure is further modified to reduce band gap. The optical waveguide is confining heterojunctions (cg, >25%). both carrier leakage and the optical produced by sandwiching the first three In practice such thin layers are difficult confinement effects of the active layer. layers between two outer layers of even to grow by liquid-phase epitaxy (lpe). This five-layer structure uses an asym- greater band gap (and lower refractive So it is doubtful if any of the five-layer metrical layout with one of the outer index). If certain conditions are satisfied, devices so far made incorporate any heterojunctions having a large compo- the characteristics of the two regions large degree of independence between sition step. The asymmetry allows the may be made sufficiently independent optical and carrier confinement. active layer to be made wider, to ease of each other to be individually opti- In the absence of sufficient inde- the 1pe growth problem. Also the outer mized for any given application. The pendence between the two types of heterojunction with the large step can be active-layer thickness may be adjusted confinement, compromises have to be positioned on the p side to intercept the to give low-threshold current density made in the design. For devices with predominant electron leakage from the and the optical resonator may be de- wide optical distributions the com- active layer. The onus of mode discrimi- signed to give the appropriate optical promise is generally at the expense of nation is then put entirely on the oppo- distribution and suitable discrimination carrier confinement. The composition site outer heterojunction. against unwanted transverse modes. This steps at the boundary of the active layer Also lasers of the above design are is of benefit where a wide optical are made smaller than would be accept- described that combine narrow beam distribution is required in the direction able in a double-heterostructure laser. widths and relatively wide single-mode perpendicular to the junction plane. optical distribution in the direction per- The condition for providing indepen- pendicular to the junction, with low- dence between optical and carrier con- Fig 1: Schematic diagram of layer threshold current density, low tempera- finement is largely determined by the structure with AlAs content, dielectric ture coefficient of threshold, and the active layer and the heterojunctions constant, band diagram and optical ability to work efficiently in a pulsed which confine it. The steps in AlAs con- distribution. mode at currents up to 10 or 20 times tent at the boundaries should be large threshold. The performance is compared Fig. 2: Pulsed output power from one with that of symmetrical five-layer and Thompson et al are with STL at Harlow. end of various lasers versus current. double heterostructures.

Curve diode ref lwi dth (pm) A49L1/ 5No 102 B46L30/8 Yes 235 14° C49L20/9 Yes 243 le DDHPK53 No 122 16

Electronic Engineering December 1976 41 .3rirtregifrlre>77err " Mel

A typical asymmetrical five-layer sisted of reducing the cooling rate from currents of all the lasers lie between structure is illustrated in Fig. 1. Injected the original 0,2°C/min to 0,05-0,1°C/min 0,6 and 1,1 A (900-1500 A/cm 2). The carriers are confined within layer 3, and maintaining this rate •from the light-current characteristics of the asym- and the light is guided within layers start of cooling to the end of the growth metric five-layer lasers remain straight 2-4. The layer dimensions and composi- of the important layers. Using these up to about 10 times threshold with in- tions are chosen to confine the carriers methods it has been possible to grow cremental quantum efficiencies for total within the active layer 3, even at elevated layers of Ga o, "Al °,05 As of thickness light emitted between 33 and 50%. temperatures, whereas the light is down to 0,051.Lin with thickness variation At higher currents there is some satura- allowed to spread out of layer 3 but is of the order of ±0,02 p.m. tion which amounts to less than 10% still restricted to a single transverse All layers relevant to the lasing action at the point where the laser stops opera- mode. In a comparable double hetero- were doped at 5 x 10" cm -3 except the ting due to permanent end face damage. structure, where it is necessary to use an active layer in slice KW 39 where the The latter arises from the intense optical AlAs composition step 8x at the boun- higher doping of 2 x 10" cm -3 was field and occurs at an optical power dary of the active layer of at least 0,25 used. Sn was used as the donor and Ge density of between 3 and 5MW/cm 2, for satisfactory carrier confinement, the as the acceptor except in the active which for these lasers, where the near- condition for light to spread over atotal layers of the KW and PKB slices. field optical distribution is spread to a width greater than 1pm (d8x<0.009 After growth the slices were contacted width of about 0,71.1.m, corresponds to .i.rn) requires the thickness d to be less by evaporating Au/Zn and Au/Sn on to about 20-35 W/mm of junction width. than about 0.04 p.m. Considerable de- the p and n sides, respectively, alloying The light-current characteristics of the mands are imposed on the liquid-epitaxy at 500°C and further evaporating ni - narrow-beam double-heterostructure la- growth. However in the five-layer struc- chrome-copper and Au, respectively, on ser starts to curve at a lower current ture of Fig. 1the demands are less strin- the two sides. The slices were then than asymmetric five-layer structures. gent. Optical asymmetry allows clax cleaved into bars and areflective coating The peak optical power density pro- to be increased to about 0.015 i_tm for was normally applied to one of the duced at a current of 23 A was greater the same optical spread and the addition cleaved faces by evaporating a half- than that of the five-layer structures. of a second barrier for electron con- wavelength-thick insulating layer of Figure 3shows far-field patterns in the finement at the layer 4/5 interface allows A1,0 3 and then a layer of Al. The bars plane perpendicular to the junction of 8x to be reduced without causing elec- were parted with adiamond saw to pro- the two asymmetric five-layer lasers tron leakage, so that the thickness of d duce individual lasers of 240 p.m width, with reflectors and the double hetero- can be increased to about 0.08 p.m. The and lengths, of 300, 425 and 550 m. structure laser whose light-current char- size of the AlAs composition step at the Evaluation of asymmetric five-layer acteristics are illustrated in Fig. 2. The 1/2 interface in Fig. 1, is chosen to pro- lasers was carried out on 20 different effective beam widths are about one- vide control of transverse-optical modes. slices (KW series). Measurements were third of those produced by a normal It is made sufficiently small that the made on a sample of 30 or 40 lasers of double-heterostructure laser because of critical angle of reflection at the inter- various lengths from each slice. For the spreading of the optical distribu- face is less than the propagation angles comparison, measurements were made tion in the laser waveguide. The lasing of all transverse modes except the zero- on three narrow-beam symmetrical spectrum of one of the above asymmetric order mode. double-heterostructure lasers (PKB five-layer lasers is given in Fig. 4. A series). series of about 20 longitudinal modes Device structures Figure 2 shows the light-current are present at a current of 30% above The heterostructure layers were grown characteristics for pulsed operation threshold, centered on a wavelength of by conventional liquid-phase epitaxy (pulse length, 200 ns) of various narrow- 8200 A. This wavelength tends to be using a rotating graphite crucible in a beam lasers comprising three asymmetric about 100 A shorter than the centre of vertical furnace. Thin layers of (GaAl)As five-layer devices and one double-hetero- the spontaneous-emission spectrum due were more difficult to grow than GaAs. structure device. Two of the lasers are to the high electron concentration The 5 at.% AlAs included in the thin 240 p.m wide with reflectors at one end injected into the active layer at threshold layers for the present work was sufficient and two are approximately 100 p.m (1,5 -2) x 10" cm-3). The effective to change growth characteristics con- wide without reflectors. The threshold spectral width is about 15 A. This siderably from that of pure GaAs. To increases as more current is applied. attain the same control of layer thick- Fig. 3: For field emission pattern in the The near-field pattern in the junction ness as was originally obtained small direction perpendicular to the junction plane of one of the asymmetric five- changes were made in the growth sched- for (a) five layer LGR lasers and layer lasers is given in Fig. 5. for currents ule. The more important of these con- (b) DH laser. of 1,3 and 3,3 times threshold. Although

40 ° 30 ° 20 ° 10 ° 0° 10 ° 20 ° 30 ° 40 ° Angle perpendicular to junction plane 91 3a

42 Electronic Engineering December 1976 L considerable fine structure is present reflector showed that the immersion efficiency. This is expected if they remain the total distribution is reasonably uni- reduces the reflection coefficient of the well behaved and no cross modes are form and improves at higher currents. output face to 0,17. This experiment generated as a result of the less favor- Figures 6and 7give threshold current indicates agreement with the relation for able length-to-width ratio. The average density versus reciprocal length for an threshold current of Eq. 1. internal efficiency is estimated to be asymmetric five-layer laser and a In Fig. 7 the threshold/reciprocal- 0,66+0,15. The optical absorption double-heterostructure laser. These re- length dependence for double-hetero- coefficient should be 11+4 cm -1 .Precise sults represent the best 60 % or so of structure lasers from slice PKB 21, with measurements gave cc = 9 ± 2cm -1 . those lasers measured. They illustrate the d -- 0,11 gm and a relatively wide far Figure 9 applies to the double- low values of threshold which can be ob- field beam width of 33° is shown. The hetero-structure slice PKB 5 and the tained for lasers of average beam width. threshold current density of 650 ± 50 incremental quantum efficiency of most Also small increases occur for narrow- A/cml obtained from lasers of length of these double hetero-structures is beam-width lasers. On each figure the 550 gm with reflectors is the lowest very similar to that of five-layer approximate relation, Jt — 4000d figure reported for double-heterostruc- devices. However shorter lasers have ture (GaAl)As lasers of normal compo- lower than expected efficiency due In (1/12,11, Serf A \ +28 (a+ sition at 300°K, A study of the behaviour to the generation of internally reflected 2L k cm') (1) of narrower-beam (25°) double-hetero- cross modes. Even for the intermediate- is also plotted. Here d(gm) is the active structure lasers from slice PKB 5 with length lasers plotted in Fig. 9the reflec- layer thickness, a(cm -1) = optical d = 0,09 m, gives that the threshold tion coefficient was reduced from the absorption coefficient, L (cm) = laser current density for lasers of length sawn edges (by proton bombardment) length, Ri and R, = reflection coeffici- 550 p.m with reflectors was 750 + 50 before consistent results could be ents at the laser ends, Sett(gm) = the A/cm'. This performance is relatively obtained. Double-heterostructure lasers effective width of the optical distribution poor when compared to the threshold from other slices have shown consider- in the plane perpendicular to the junc- relation of Eq. 1 than that of the average internal efficiency for the lasers tion, and k is the coupling coefficient PKB 21 lasers, and is an indication of a from slice PKB 5 is 0,67 ± 0,15 which describing the effective relative optical loss of injected carriers across the con- is similar to the five-layer lasers. intensity over the active layer width. This finement barrier due to the injected expression is areasonable approximation concentration being higher. Variation with composition in cases where the second term is not Figures 8 and 9 compare the incre- With the exception of the three slices less than 50% of the first. mental quantum efficiency as afunction KW 32, 36, and 39, where the carrier- Figure 6gives the threshold perform- of laser length between aset of asymmet- confinement step corresponds to 12% ance of a set of asymmetric five-layer ric five-layer lasers and double-hetero- or less change in AlAs content, all the lasers with relatively narrow optical structure lasers, both of narrow beam asymmetric five-layer lasers (KW slices) distribution from slice KW 27. The width. The results are typical of the show threshold current density in reason- current density measured for lasers of majority of all lasers. The reciprocal able agreement with Eq. 1. The AlAs length 550 gm of 500 ± 30 A/cm 2 is the of the incremental efficiency of total steps for carrier confinement were at lowest reported for Fabry-Perot (GaAI) emission 1/n, (including the optical least 20 % in these lasers. As lasers at 300°K. The previous lowest power calculated to be dissipated in the In three other sets of five-layer lasers of 575 A/cm 2 was obtained with a sym- reflector) is plotted against 2L[1 n(1R,- from slice PK 68 (d = 0,07 gm) and the metrical five-layer PK 64'. The improve- R,)] -1 = x. The straight line so pro- longer lasers from slices PK 42 and 64 ment can be attributed to the use of a duced has an intercept on the ltn, axis (d= 0,04 gm) also approximately obeyed reflector and is attained in spite of a of l/n o,where n, is the internal quantum Eq. 1in spite of their 12% barriers. How- wider dand alarger Serf. efficiency, and an intercept of the x axis ever, in these lasers there were additional Experiments on five-layer lasers from of —1/a, where cc is the coefficient of 18 % confinement barriers on both sides optical absorption. Figure 8 applies to s.lice KW 49 with the narrow beam of the active layer, within 0,4 gm or less, width shown in curve A of Fig. 3 re- the asymmetric five-layer slice KW 49. to provide confinement back up. How- vealed that the threshold current density The shortest lasers show the highest ever some of the shorter lasers from slices for 5501.cm long lasers with reflectors is Fig. 4: Spectrum of a five layer LGR PK 42 and PK 64 showed excess current. almost double that for similar lasers laser at current 30% above threshold. This arose from the higher injected with wider beam width from slice carrier concentration. KW 27, but is still below 1000 A/cm 2. Fig. 5: Optical density distribution Of the five double-heterostructure A plot to determine the effect of immer- across output face of five layer LGR slices only slice PKB 15 (with the smal- sion in CHO, on a laser without a laser. lest d of 0.06 p.m) showed appreciable

KW49 L20/9 1, 3 x It

intensi ve ati

4- 8100 8150 820 8250 Fig. 4 Wavelength (X)

Electronic Engineering December 1976 43 excess threshold current at room dividing line between wide- and narrow- The optical gain g becomes temperature. However, carrier confine- beam behaviour occurs at d-H-c=0,1 (4) ment in these lasers was not sufficient p.m. The symmetrical five-layer lasers where go is the gain loading factor of for satisfactory operation at 65°C. PK 42, 64, and 68 show less sensitive unity and the guided wave is within the The asymmetric five-layer slices KW dependence of beam width on d. The gain region. Expression (1) for the 36 and 39 required about twice the cur- important parameters are the thickness threshold current density can be obtained rent for threshold predicted by Eq. 1. of the three centre layers and the AlAs from Eq. (4) by using a linear relation The 5% AlAs step used for carrier con- step size at their outer boundary. between go and current density J of the finement would be insufficient on its In the symmetrical devices d must be form ge—(J1d—A)B -1 (5) own to provide this degree of confine- small and 61/2 varies approximately as and equating g at threshold to the sum ment for electrons or holes and both the lid. In the asymmetrical devices dmay be of the dissipation loss aand the end loss outer AlAs composition steps must have larger but 0,/, is an even more sensitive In(l/R IR2)2L -1 . Empirically A and B been involved. Slice KW 36 did not function of d. have the values A 4000 A/cms p.m show temperature-sensitive behaviour, and B 28 A/cm p.m. and hence the factor of 2 increase in Threshold characteristics The far-field beam pattern is obtained current at room temperature is accoun- The optical distribution in the direc- using aFourier transform of the optical ted for by those minority carriers which tion normal to the junction of the guided field distribution as described by Kirkby spilled out of the active layer but re- wave in the heterostructure guide may et al. Because the angles are small the mained within the three centre layers. be derived in terms of the thickness and obliquity factor may be neglected. dielectric constant of the various layers Slice KW 32 (with a 12% confinement The optical distribution for the TE 00 step) showed some increase in threshold and the wavelength of the radiation mode has been computed by conven- current beyond the expected value. concerned. This is required for obtain- tional methods for aseries of four-layer With the exceptions of slice KW 39, ing the threshold current density and the structures which are representative of where the active layer was doped to perpendicular far-field beam width. the five-layer structures used for the 2x 10 18 cm-8 with Si and of slice PKB Expression 1for the threshold current KW lasers. Four-layer structures were 15, a marginally confined double- density involves the optical loading analyzed to avoid the introduction of heterostructure laser, there is little dif- factor of the active layer. This factor is too many variable parameters. The ference in the efficiency of the longer given by the ratio of the total optical results, can be extended to apply to lasers. The same is true of the shorter energy contained in the width of the five-layer structures by approximate lasers if the narrower-beam double- guide to that contained in the active methods. The layer compositions in- heterostructure lasers that suffer from layer. This is expressed in terms of a vestigated are illustrated in Fig. 10. cross modes are excluded. The average total effective width Soft of the guided The difference in dielectric constant estimated internal efficiency of most mode and a coupling constant k for the ,3c at the heterojunction boundaries is lasers lies around 65% with afew lower active layer. Serf is given by taken as being linearly related to the at around 55%. The estimated optical co step in composition S. of the Gai-aAla absorption coefficient lies close to Sett = I IdslImax, (2) As by Sc=4,338x. 10 cm-'with some values, particularly Figure 10 shows how Seff and Sore for the double-heterostructure lasers, where hoax is the peak optical intensity vary with the thickness d of the active of around 8cm -'. Of this 4cm -' is over the cross section and ds is an ele- layer for two values of b of 0,8 and 1,2 estimated to be due to free-carrier ment of distance in the direction normal p.m. In both cases the optical confine- losses, leaving 4-6 cm-'to be accounted to the junction, k is given by ment is determined mainly by d for for by interface roughness. k= fdldsllooixd, (3) d>0,12 p.m and mainly by (b+d) for The ratio of the threshold current at d<0,10 p.m. The switch-over from one 65°C to that at 10°C lies close to 1,5 for where the integral is taken over the condition to the other is more abrupt almost all the well-confined five-layer width of the active layer. The optical where b is larger and guiding in the lasers of the KW series. loading factor is given by Seted. combined layers is stronger. Although The total beam width to the half- the effective optical width becomes power points of these lasers varies from Fig. 6: Threshold current density relatively independent of d when versus reciprocal length for low 12° to 56° over the range investigated. d<0,10 p.m the quantity Sere continues In the asymmetric five-layer lasers of the threshold five-layer LGR lasers. to increase rapidly as d is narrowed. KW series the beam width is asensitive Fig. 7: Threshold current density This is because the peak of the optical function of the thicknesses of layers 3 versus reciprocal length for low distribution moves out of the active and 4, d and c. As a rule of thumb the threshold DH lasers. layer into the b layer, and the op tica

L (jam) L (with reflector) 500 400 300 500 400 300 cs"I-- _ I I E >, goo Gradient — -Double heterostructure Slice -0 u (..1 1400 E . 28 u o a - Seff k PKB 21 -C _ d=0,11pm Seff=0,34m 4, = current 1020 0 c cu - -0 \4, I 0 S/k=0,42»m 93 =33 ° 5-01 ..e. L ..." oe 7 ...... " S1 ice KW27 e (1) 800 o - d=0,04m Sef f=0,39pm -0 Threshold 600 E o=wi th reflector R2=0 '8 -0 Gradient = 28 Seff /k •-) c"r;,( - =35 o 400 cD 200 o=wi th reflector R2=0,8 200 -t>without reflector R2=0,32 a cm- 1 [acm -1 _10 10 20 30 -10 0 10 20 30

in (1 /R ,R 2) /2L (cm -1 ) To (1/R 1R2)/21. (cm-1 ) Fig. 6 Fig. 7

44 Electronic Engineering December 1976 intensity in the active layer can become Consider a structure designed to a near-field width lying within a 3-1 very small due to the large dielectric- produce the same optical distribution as range, the low end applying to the limit constant step which bounds it on one for d= 0,1 !£m in the four-layer struc- in weak guiding and the high end apply- side. Under these conditions the term in ture of Fig. 10. According to Fig. 11 ing to the limit in strong guiding. the threshold Eq. 1 containing Sere (Z=0) d in the five-layer structure is The four-layer optical distribution rapidly becomes dominant and causes 0,08 i.un with c=0,06kun or d=0,06 i.tm may also be described in terms of strong an increase in threshold current. To with c=0,14 gm. The added thickness and weak guiding. Take for instance, combine a value of Sert of around 1gm of ccontributes about one-third of the curve C which applies to the widest with a threshold current density of less effect of the thickness reduction in d, optical cavity. At the low Serf end the than 1500 A/cm' it is necessary for d assuming that this relationship will guiding is mainly controlled by the to lie in the range 0,09-0,11 p.m. This is apply over a range of values of d in active layer, which, however, only close to the value which, if the b layer the cutoff condition for small c values. weakly guides, allowing an appreciable were infinitely wide, would produce a The computed optical distribution in proportion of the light to extend outside. cutoff condition. the four-layer structure has been used for The relation between Sert and O lies This observation gives a means of deriving the far-field beam width in the close to the weak-guiding asymptote. extending the analysis from four-layer to plane perpendicular to the junction. But, as d is narrowed eventually the the five-layer structure. Consider the The far-field beam width is a useful light starts to fill the wider optical cavity structure shown in the inset of Fig. 11 means of assessing the spread of the and for this value of b the dielectric which is a four-layer structure in near field in any laser and giving an barrier at the far side provides fairly which the clayer of the five-layer struc- indication of the permissible peak strong guiding. Curve C moves across to ture is retained but the blayer is omitted. optical power output that occurs at the higher values of Seff to lie close to the If the cutoff condition for this struc- power density of 3-5 MW/cm'. In Fig. strong-guiding asymptote. Curve B ture is a function of the thicknesses d 12 the relation between Serf and the applies when the wider guide has weaker and c, the two layers of the new structure beam width to the half-intensity points guiding characteristics because of the replaces the single dlayer of the original. 01/2 for four-layer structures is plotted smaller value of b. For small Sett The same behaviour should result if the for three values of b, dvaries. curve B shows aless pronounced version thickness of the two new layers is As acomparison the relation between of the behaviour of curve C, but for varied. This was shown by varying the Serf and 01) ,is plotted for the zero-order the largest value of Serf reverts to weak original d layer over the important mode in a double heterostructure with guiding as the optical distribution range 0,09-0,1111m. Figure 15 shows 0,2 AlAs composition steps defining the penetrates beyond even the wider optical the combinations of d and c that give active layer. The upper branch corres- cavity. Curve A, for the smallest value an unchanged cutoff condition for two ponds to large values of the active-layer of b, shows a behaviour similar to the different values of the asymmetry -7) of width in which the guided wave is weakly guided branch of the double tightly confined within the active layer the main dielectric-constant step and for hetero-structure. two different values of the composition and the lower branch corresponds to The curves of Fig. 10 for effective of the additional c layer. The curves small values of the active-layer in which optical width and of Fig. 12 for far- can be generalized to a variety of di- the majority of the optical distribution field beam width may be used in con- electric-constant steps Se by using the is located outside the active layer in the junction with the threshold-current normalized thicknesses C and D [C- form of exponential tails extending into relation of Eq. 1to obtain a theoretical 2Tr(h)q 2c/X,D=2rr(Se)h/ 2d/X. The curves the surrounding layers. To emphasize the relation between threshold current den- -show that d must be narrowed as c is two types of behaviour asymptotic sity and beam width. increased to maintain the behaviour. curves are plotted, curve I for perfect This is illustrated in Fig. 13. Three The c layer reduces the threshold confinement of one-half sinusoidal cases are shown: a double heterostruc- current density in two ways. It allows period of the optical distribution within ture with 20% AlAs confinement steps, d to be reduced and so reduces the left- the active layer and curve II for apair of the four-layer structure investigated in hand term of Eq. 1. It also reduces the expotential tails both outside an active Figs. 10 and 12 with two values of b, right-hand term by increasing k. be- layer of infinitesimal thickness. A given and afive-layer structure with two values cause the reduction in dcan be regarded far-field beam width may correspond to of b and with an active-layer width of as occurring over the poorly coupled 0,07 gm. The latter curves are estimated part of the original active layer, and Fig. 8: Incremental quantum efficiency assuming that the substitution of the sometimes, because the peak of the versus laser length for narrow beam active layer in the four-layer structure for optical distribution is drawn out of the LGR lasers. Fig. 9 As for Fig. 8 but for a pair of layers comprising an active b layer and back the active layer. narrow beam DH lasers. layer of thickness d' and an additional c

L mm (wi th reflector) 3,00 0,2 0,4 0,6 0,8

Slice 49 d=0,75pm

Seff =0,73pm 0=17 o o= with reflector, R2=0,8 20 ;\ Ge , a= wi thout ' ouble heterostructure ,0)(, reflector, R2=0,32 Slice PKB5

Electronic Engineering December 1976 as 4M3ilh:( SkyCap® ceramics at the centre of most applications

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46 Electronic Engineering December 1976 b—4 d x- 0,265;0,250: ' ' 05

Seffi k b. O, 8pm 0 1,0 X 0,85 jim ef

‘I- 0 lilt 0,06 0,10 0,14 0,10 0,14 d (pm)

Fig 10 layer of appropriate thickness to give the Fig. 10: Theoretical relation between Double-heterostructure lasers with same value of Serf will not interfere with effective optical width Serf and active similar carrier confinement steps (a.120% the Serd0 i/2 relationship. The threshold layer width d for four layer LGR's. AlAs) have also been designed to give, may then be obtained using the appro- at one extreme, threshold current densi- Fig. 11: Relation between widths of priate value of d' (1200 A/cm 2) Figure 13 shows that the double and, more seriously, increases much Fig. 13: Estimated relation between far- heterostructure is apparently the best of more rapidly with temperature. field emission pattern and threshold the three structures for combining low The design of both the five-layer current density for four and five layer threshold and narrow beam width. The devices and the double-heterostructure LGR lasers and three layer DH lasers lower branch of the curve has not yet devices is limited by the layer structure using the expression: J0=3000 d1 been achieved due to difficulty in growing which can be grown at the present state 28 [a + In (IRIR2)(2L) -1]S effici the narrow active layer and obtaining of the art in liquid-phase epitaxy. The adequate carrier confinement. The five- of the 6=0,8 four- and five-layer main problem is that if the active layer layer structure gives the lowest threshold structures is associated with the same is grown with a large enough compo- current at wide beam widths, the actual effective width of the near field as the sition step to retain carrier confinement threshold being determined to aconsid- 12° beam width of the b=0.,4 four- at high temperature it must be made erable extent by the value of d' used. The and five-layer structures. very thin. The asymmetric five-layer four- and five-layer devices become un- The majority of the work has been structure is at an advantage because of satisfactory for beam widths below a carried out on the asymmetrical five- the additional carrier confinement pro- value that depends on layer thickness layer structure and it has proved a vided by the outer heterojunction and composition due to low values of the versatile design, capable of producing boundaries, one of which may be chosen coupling k. The curves in this region are lasers at one extreme with threshold independently of the optical require- shown dashed. Figure 13 should not be current densities as low as 500 A/cm 2 ments. To provide comparable perform- used for assessing structures for high- and at the other extreme with far-field ance in a symmetrical double hetero- peak-power use since there is no simple beam widths perpendicular to the junc- structure would require a confinement relation between effective width Sere tion plane of 15° or less and with thres- step of 25-30% AlAs and as a result an and 01/2.For instance the 18° beam width hold current density still 1000 A/cm 2. active layer width of less than 400-300 A.

1,8 lege ‘,=0,85ym Four- layer 4-4d 1,6 structure ,1,,7s_7e 0,43 Ç\Small d I 1,4 \s4 x= 0 , 26 50 ,2 50 --(5- \‘ A \•,>. . —Curve A g C 1,2 .\\ b=0 ,4pm 0,6pm1,2pm A_ 1,0 variable 0,8 _ OH \\ structure\..,- , 0,6 • _ x=0 251! ***% 0,4 0 0 0,2 Asympt5ate for di electri c step 10 ,20 30 40 50 Full beam width between half power poi nts ea (degrees)

Electronic Engineering December 1976 47 monolithic AiDconverter ensationalt anylanguage.

Trust Teledyne Semiconductor to come up -With the 8700 series an unlimited range of with asensational new 8700 series of input signal voltages can be converted and CMOS A/D converters which combine on a unlike most IC converters, the outputs are not single chip all linear and digital circuits required encoded and operate at standard logic levels. to convert an analogue signal.The 8700's are So, if you require adata converter to not fast converters which means that because translate your analog information into digital 700 of their integrating conversion principle, they signals for subsequent processing and analysis, sorbs are highly accurate, reliable and inexpensive. it's got to be the 8700 series fromTeledyne With their latched parallel binary outputs, the Semiconductor. A logical decision. converters are logically compatible with A 31/2 digit BCD version is also available. processors such as micro computers and Teledyne Semiconductor 1rTELEDYNE mini-computers, tri -state and other output Heathrow House, Bath Road, Cranford, versions becoming available shortly. Middlesex. Tel: 01-897 2501. Telex: 935008. SEMICONDUCTOR 44 on enquiry card The software challenge for microprocessor engineers

Microprocessors are likely to become an essential tool for the electronics engineer. Alan Potton explains the need to understand and the ability to use software to successfully exploit this exciting new device.

Of all developments in electronics since with occasional recourse to Boolean In early microprocessors, interfacing the arrival of the transistor, micropro- algebra, Karnaugh maps or sequential the microprocessor chip to the remain- cessors are likely to have the greatest system theory. In any case, msi and der of the system was by nto means impact on the way engineering systems lsi tends to require an intuitive approach straightforward and the systerh design of all kinds are designed. The analogy since although well established theoreti- involved a substantial amount of logic has been drawn that if the invention of cal design techniques exist for combina- hardware. The more recent micropro- the digital computer is compared with tional and sequential digital systems cessors have much simpler input-output the invention of writing then the coming employing gates and flip flops, no such arrangements and the amount and com- of microprocessors can be compared generally accepted and useful body of plexity of the associated hardware is with the invention of printing. In the theory exists to handle the design of correspondingly less. The amount of same way that the use of microprocessors systems composed of more complex design effort involving hardware is will influence all spheres of engineering system elements such as counters tending to decrease as the amount of requiring new approaches, digital sys- registers, et cetera. software design is increasing. The tem designers themselves will need to With the arrival of lsi capability by the emergence of programmable interface acquire new skills and techniques to semiconductor manufacturers a few chips has accelerated this tendency. The exploit these devices. years ago a common assumption was characteristics of aprogrammable inter- The transition from discrete compo- that system design would concentrate face are under the control of the pro- nent logic design to the design of sys- on the use of Isi and msi for 'one off' gramme which determines the overall tems using integrated circuits was a and short production run systems with system behaviour. relatively painless process for most custom design lsi being widely used for engineers. The system elements, gates systems required in quantity. In practice, flipflops, etc, changed in form but not in although custom designed lsi chips have Typical problems function. The arrival of msi devices a place in the current scenario, another As an example of the options open to actually made life easier for the digital option has become available, that of the digital systems designer, consider a system designer since the behaviour of programmable systems using micro- simple temperature control problem. registers, counters et cetera was well programmed roms or microprocessors. Suppose it is desired to heat a quantity understood from the equivalent ssi An essential feature of both micropro- of material to a temperature 01, hold it circuits. grammed rom based systems and micro- at that temperature for aperiod of time processor based systems is that the tl, allow it to cool to a temperature 02 Intuitive design behaviour of the system is determined and hold it at 02 for a time interval t2 Up to this time the design of digital by stored data comprising the program We assume that simple on-off tempera- systems was often an intuitive activity or microprogramme. The design of the ture transducers indicate whether the system therefore involves construction temperature is above or below 01 and Alan Potton is senior principal lecturer at of the programme or microprogramme 02. Such temperature control systems Leicester Polytechnic. in addition to the circuit design. are widely used in situations ranging

ireater control

.; Start

Reset

Retet Coun er Clock Fre t Count \;. Clock Detect MN

Detect

Flg. 1

continued on pogo 53

Electronic Engineering December 1976 48 1 LINEAR

With the Signetics range of ICs you get more choice than with any other range of integrated circuits in the UK. And they're not all digitals. There's a big healthy slice of linears. There are 'industry standard' linears for industrial, EDP and communications applications .. . a variety of packages and military options are offered. AND there are high performance state-of-the-art linears that could help put you out in front in tomorrow's market place. For awallchart giving arapid run-down on all Signetics linears use reader enquiry service no.151 VOLTAGE REGULATORS Labour- saving range newly extended

The time and labour saving Signetics devices - the µA7900 family -for negative Voltage stabilisers -plastic or metal µA7800 family of voltage regulator ICs operation. packages according to choice. Also available, four-terminal devices for has recently been considerably supple- Four further devices have also been adjustable voltage output. mented. The original family comprises introduced. These, with the aid of two three series of devices with output capa- external resistors, provide for continuous bilities of 150mA, 500mA and 1A, and adjustment of the output voltage over two adjustable types, the 78MG and fixed output options in the +2.6 to +24V approximately the same range as the fixed 79MG, are 500mA devices for positive range. Current limiting and thermal output voltage types. and negative operation respectively. overload protection are built in. Two of these adjustable types, the 78G Now, these highly popular ICs have and 79G, are IA devices for positive and For further details use reader enquiry been complemented with companion negative operation respectively. The other service no.152

PHASE-

LOCKED An outstanding choice LOOP The op-amp range is based on thirty from a source resistance of the order of ifferent types from gene altrl purpose iomn and has very low drift. The ciriûits,to_. high technolog‘ precision LM4250 can be programmed by an external devices, anZ's4,in'cludis' dual d quad resistor and be operated from supplies as versions, and V variety of packaging low as ± IV with negligible power con- options. sumption. And the LM124 comprises four 'Old reliables' like the 741 continue, precision op-amps in one package which An attractive newcomer to the PLL range but there's no shortage of advanced operates from asingle ±5V rail. is the 564. This IC can be used with devices such as the 535 developed by supplies from 5to I2V. Operation is up to Signetics. This IC, functionally the same For a list of op-amps complete with pot- 50MHz with low noise and low carrier as, and pin compatible with, the 741,1as ted data use reader enquiry service no.154 feedthrough. Standard FM and vastly improved slew rate and input frequency-shift keyed signals can be characteristics. Another Signetics innova- demodulated without additional tion, the 536, has an FET input and components. carries a bonus of high slew rate and high A variety of other PLL circuits are offered including types with FM, AM and output drive. tone-decoded outputs. Reader enquiry Three other 'stars' are the LM 108, service no.(153 for further information. LM4250 and LMI24. The LM108 is a SiflfllltiCS bipolar op-amp which can be operated ICs from Mullard

50 Electronic Engineering December 1976 signuties Widest range of riMERS ICs from Mullard ICs in the U.K. Many roles •Logic •Interface he 555 timer needs no introduction. This •Memories •Linears lassic IC lends itself to diverse applica- ons — and with the minimum of •Microprocessors :High REL ICs eripheral components. A dual version (556) is also available, nd quad versions (553 and 554) rated at DISPLAY INTERFACES 00mA per output. Reader enquiry service LED and gas tube drivers 0.155 for further information. COMPARATORS Three devices definitely worth knowing about in the range of display interfaces are the 582 and 584/585. The 582 comprises six drivers each having an output capability of 400mA with a correspondingly low saturation S voltage —a natural for LEDs. INPUT — The 584 and 585 are, respectively, TRIGGER cathode and anode drivers for multiplexed OUTPUT gas discharge displays. Both can drive up to nine segments, and the current of the 584 can be programmed by one external resistor. Reader enquiry service no.157 'one burst generator—one of many uses for further information. or the 556 timer. D-MOS DEVICES High-performance switch arrays WECIALISED ICs The Signetics D-MOS (Double-diffused to choose from MOS) technology is exploited in a series Range includes fast and sensitive Schottky lore scope of analogue switch arrays capable of very types. Dual and quad devices available. or designers high speeds, excellent transient response Note the NE521, a dual type with and high voltage operation. 12ns propagation delay and 20µA maxi- glance through the list of linears The SD5000 series handles a wide mum input current. TTL compatible eveals a variety of specialised ICs which variety of analogue switching and driving strobes and output. Large common an't be neatly categorised except in that applications. Speed is high and feed- mode input voltage range. hey all offer increased scope for the through and feedback transients low. Also check the LM139 series. Each quipment designer. To mention but The SD5300 is an 8 x 2 telephone type comprises four independent precision alf-a-dozen . crosspoint switching array with first-class voltage comparators in a single package. transmission characteristics. Outputs are Single supply operation down to +2V. Lnalogue compander 570 — two indepen- TTL- and CMOS-compatible. Reader Directly interfaces 'TTL and MOS. ent signal channels: each may be used as enquiry service no.158 for further Reader enquiry service no.159 for dynamic range compressor or expander. information. further information. ;yrator simulated inductor TCA580 —with No resistors and a capacitor replaces . . iductances of up to amillion henries. rariable audio delay line TDA1022 — IC Distributors-Nationwide ucket brigade circuit providing delays For linear and other integrated circuits contact: rom 0.5 to 50ms. A. M. Lock & Co. Ltd., Gothic Electronic Semicomps Ltd., Neville St., Middleton Rd., Components Ltd., Box 301, Wellington Road, ,tepper motor driver SAA1027 — performs Oldham,LANCS.OL9 6LF Beacon Hse, Hampton St., London Colney, St. Albans, II functions between data information Telephone: 061-652 0434 BIRMINGHAM BI9 3LP HERTS. AL2 IEZ Telex: 669971 Telephone: 021-236 8541 Tel: Bowmansgreen 24522 ulses and stepper motor windings. Telex: 338731 Telex: 21108 'ime-proportional control TDA1023 — Apex Components Ltd., Semicomps Northern Ltd., Quarndon Electronics Ltd., elivers positive gate pulses at zero 396 Bath Rd., Slough, East Bowmont Street, Slack Lane, DERBY BERKS. Kelso, ROX BURG HSH IRE rossing of the mains for triggering Telephone: (0332) 32651 Telephone: (06286) 63741 Telephone: (05732) 2366 riacs. Telex: 37163 Telex: 848519 Telex: 72692 witched-mode control TDA2640 — all ontrol and protective functions for SDS (Components) Ltd., Semicomps Ltd., Farnell Electronic Hilsea Industrial Estate, North Midlands Division, riving single-ended switched-mode power Components Ltd., Gunstore Rd., Portsmouth, Ingrow Lane, Keighley, upplies. Canal Road, LEEDS HANTS. P03 5JW WEST YORKSHIRE Telephone: (0532) 636311 Telephone: (0705) 65311 Telephone: (0535) 65191 For data on these devices use reader Telex: 55147 Telex: 86114 Telex: 517343 nquiry service no.156

Mullard Limited Mullard House Torrington Place London WC1 E7HD Telephone 01-580 6633 Telex 264341 Mullard •

614355 o86

Electronic Engineering December 1976 51 46 on enquiry card

DIGITALIN instrumentation ltd

275 AUTORANGING DIGITAL THERMOMETER

Digitron Instrumentation have chosen Electroplan The 275 features automatic zeroing, cold to distribute their range of temperature junction compensation and gives a resolution of measurement equipment. The 275 is a mains 0.1°C below 185°C and automatically autoranges powered digital thermometer covering the range to 1°C resolution up to 1200°C. A range of —50°C to 1200°C, with a large LED display and fast response NiCr/NiA1 probes is available, an analogue recorder output. together with coupling and scanning units. with

aservice to measurement

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52 Electronic Engineering December 1976 from domestic washing machines to industrial chemical process plants. Figure 1shows atraditional approach to the problem. Generation of a start signal sets the first RS flip flop which Heater control switches on the heater. The heater D remains switched on until the tempera- T>92 ture reaches 01 when the first bistable is reset. At the same time, the second 6 RS flip flop is set. This enables the input 05 T>91 to the first counter and switches on the ROM 128x10 heater whenever the temperature drops A D Load below 01. When the counter reaches Start Address Pro rammable regir D Count down counter NN, determined by the clock frequency and ti, the bistable is reset which triggers A the first J-K flip flop into the set condi- Detect Al Zero tion. The heater remains switched off A until the JK flip flop is reset when the temperature falls below 02. This finally sets the second JK flip flop initiating another timing cycle during which the heater is switched on when the temperature falls below 02. Formal sequential Fig. 2 system theory caq be employed but

11••••••11.11111•••11111111•1111•11111111•11111111.111.1111•111e111..1.1.111•111•••• most engineers appear to design systems such as this by intuitive means based on an understanding of the circuit elements and past experience.

Alternative Approach An alternative approach to the problem is demonstrated in the rom based microprogrammed system shown in figure 2. This implements the description of the problem given in figure 3. Figure Heater ON 4shows the contents of the rom. Various types of trade off are possible in microprogrammed systems which No usually involve a reduction in rom size at the expense of additional components external to the rom. The method of employing flags directly as address Load oop counter modifiers as shown in figure 2involves a Heater OFF fairly wasteful use of rom. Figure 4 Enable count down shows that only a small proportion of the 128 locations are actually involved in the microprogramme. Multiplexing of flags as shown in figure 5 drastically reduces the size of rom required although Heater OFF this may not result in a lower overall system. cost. This technique certainly complicates the writing of the microprogramme. A microprocessor based system is Yes shown in figure 6. As can be seen, the Heater ON system is implemented using only four oad loop counter integrated circuits in addition to aclock. Heater ON Heater OFF Enable count The programme is stored in the rom, the down number of locations used depending on the skill of the programmer. In practice an adequate programme can easily be written to occupy less than 120 locations. Ram requirements are limited to one location used as aloop counter. Having established the three methods Heater OFF for implementing the system it is instruc- tive to make a comparison. The hardware only system shown in figure 1 Heater OFF would certainly have the lowest compo- 4 nent cost and very probably the lowest overall production cost. Since the system characteristics are determined solely

Fig. 3 by the layout, changes in the system specifications may involve a consider-

Electronic Engineering December 1976 53 able amount of redesign work. Modifi- cations could be made to the time intervals ti and t2 without too much difficulty by making minor changes to the circuits which detect the terminal state of the two counters and if necessary to the clock frequency. Control systems of this kind are often required to offer aselection of temperature cycles combined with the ability to D11 switch on pumps, valves etc. Provision 010 of selection facilities such as this in- Start D9 Heater C.Ontrol creases the complexity of hardware only T Tl Flag 8 systems very considerably with any multiplex T I major specification changes usually requiring acomplete system redesign.

Greater flexibility ROM 16x12 The microprogrammed system shown Addrese Load regieter 4 Programmable in figure 2 offers a much greater degree tour, down D3 of flexibility. Changes in temperature counter set points or timing intervals in the con- A 2 trol cycle simply require changes in Detect A2 D Zero the contents of the rom. Provided the rom has sufficient capacity, a variety of A temperature cycles can be offered simply storing the microprogrammes for the different cycles in different parts of the rom. The particular cycle desired is selected by simply choosing the correct starting address to enter the appropriate microprogramme. Additional control functions are easily provided by choosing a rom with some unused output lines. Read only memory is relatively low cost and it is feasible to leave some Fig. 5 'slack' in the system for future development by allowing some spare rom capacity. The microprocessor based system shown in figure 6 would involve the highest component cost of the three Type 6800 systems at current prices. The fact that microprocessor the system characteristics are determined by the stored programme leads to avery considerable degree of versatility. In- deed, it is true to say that the same basic arrangement of four integrated circuits can be used to implement not only a wide variety of temperature, control ROM functions but also control mechanical, electrical, pneumatic and other systems. Since the microprocessor system possesses such flexibility even compared with the microprogrammed systems, it may be possible to improve the per- RAM formance of the control system considerably. In the temperature control system, by employing an analogue- digital converter to provide acontinuous monitor on temperature, a more sophisticated control algorithm could Programmable Interface monitor be implemented. The on-off Adaptor heater control could be replaced by a pulse width modulation system, the variable width control pulses being generated directly by the microprocessor. • We may also compare the three Flag Heater methods in terms of the engineering con rol skills required to develop a satisfactory system. The techniques employed in developing a system of the type shown Fig. 6 in figure Iare the traditional methods of •

54 Electronic Engineering December 1976 hardware combinatorial and sequential reasons discussed below that the cost of devices are available. Those who have logic system design. The prototype developing software for a micropro- worked with dynamic devices will be equipment would probably be developed cessor will be greater than that for say a aware that conventional oscilloscopes, with the aid of conventional oscillo- minicomputer. so long the mainstay of the electronic scopes, logic level indicators, pulse engineer, are no longer adequate for generators etc. debugging purposes. A logic analyser Software investment The same basic laboratory equipment should be regarded as the most appro- Electronic engineers readily under- would probably be adequate to develop priate instrument for this purpose. stand that the availability of appropriate systems of the type shown in figures 2 Specialised analysers relating to specific laboratory instruments can reduce hard- and 4. To design systems of this kind microprocessors are available as are ware development time and often allow however, the control algorithm needs to more general purpose instruments. more economical and reliable designs. be clearly defined, most often with the Investment in software development help of a flow diagram such as the one aids is similarly important. When a Avoiding pitfalls shown in figure 3. This is in any case a minicomputer based system is developed, There is one further pitfall to be desirable preliminary step to all of the a computer is available with a wide avoided. Many engineers having pro- design methods described. variety of aids to the programmer. A duced their first working microprocessor control/display panel allows access to based system seem to assume that they Systematic method the working registers and memory for have become overnight programming Microprogramming is no longer anew reading and writing data. Standard pro- experts. It is generally accepted that to technique. It was originally developed grammes such as assemblers, compilers, become acompetent designer of efficient to allow a more systematic method of editors etc. are provided by the com- and reliable electronic hardware requires implementing the instruction repertoires puter manufacturer. Investment in these the correct education together with of digital computers. Although very facilities is considered as a normal part appropriate training and experience. A widely used in computers, it is only of the development costs. vast difference exists between designing The purchase of a microprocessor relatively recently that the price of rom asystem which just works and designing chip set provides none of these develop- has become low enough to make micro- asystem with the proper considerations programming an economically viable alternative to hard wired logic for more general system design. Fig. 4: Contents of the read only memory. The problems presented by the design of microprocessor based systems such Address lines Data lines as that shown in figure 6are somewhat different to those arising in the develop- 6 5 4 3 2 1 0 0 1 2 3 4 5 6 7 8 9 ment of hardwired logic or microprogrammed systems. The layout of the ***0000 0 0 0 00 0 0 0 0 0 system elements is straightforward and +++1000 0 0 1 00 0 0 0 0 1 has been indicated earlier, may well be ++0+001 0 0 1 00 0 0 0 0 1 standardised. A competent digital sys- ++1+001 0 1 0 0 1 NNNN 0 tem designer would have no difficulty in 0 4'0+010 0 1 0 1 0 0 0 0 0 1 laying out aboard to accommodate the 0+1+010 0 1 0 1 0 0 0 0 0 0 elements shown in figure 6. Once de- 1•**010 0 1 1 0 0 0 0 0 0 0 signed the board should not require *1**011 0 1 1 0 0 0 0 0 0 0 modification even for quite major +0**011 1 0 0 0 1 MMMM 1 modifications in the system specifica- 0'0+100 1 0 0 1 0 0 0 0 0 1 tion. For this type of system, hardware 0+1+100 1 0 0 1 0 0 0 0 0 0 development costs are in all probability 1**'+100 0 0 0 00 0 0 0 0 0 a fairly minor proportion of the total system development costs. It is now generally accepted that for nient aids. For serious programme of reliability and efficiency. Why then most microprocessor based systems, the development they are essential. Manu- should it be assumed that the situation is major proportion of overall develop- facturers of microprocessor chips offer different when computer programmes are ment costs will be incurred in designing systems which give the facilities of a designed? As is the case in other types software, that is, in writing the micro- normal minicomputer but are designed of computer system development it is processor programme. For the unwary around the microprocessor. Engineers likely that the efficient microprocessor engineer, attempting to predict the cost should be aware that investment in such system development team will include of developing software can be achasten- equipment will be part of the develop- both hardware and software specialists ing experience. ment cost of microprocessor based with each having a good understanding Engineers have been designing on line systems. of the other's area of work. control systems involving computers for It is possible to purchase a micro- If this paper seems unduly cautionary many years, of course. In the past how- processor chip set and develop asimple and pessimistic, this is not intentional. ever, the cost of the computer meant system without the aids described above. Going back to the statements made at that only fairly major systems justified In contrast to the advice offered by the the beginning, there is no doubt that the this approach. The difference today is microprocessor manufacturers, the microprocessor will generate a truly that the cost of the computer hardware, author believes that this can be auseful major expansion in the use of electronic in the form of microprocessor chip sets educational introduction for the engi- control techniques at all levels and in all is now so low that on line computer neer. This exercise however will norm- fields of engineering. This paper repre- control is being considered for relatively ally only serve to give the engineer an sents a plea to electronic engineers not simple situations such as the tempera- understanding of what the development to be misled by the seductively low price ture control system described here. problems actually are. After this, he of microprocessor chips and to realise What must not be forgotten however will be fully aware of the need for soft- that the approach to microprocessor is that although the hardware costs have ware development aids. system design really must be different fallen in this way, software costs remain Many of the available microprocessors to that for the more traditional types of the same. Indeed, it may well be for are dynamic although a few static digital systems.

Electronic Engineering December 1976 55 47 on enquiry card Designed forthe70's GRIPS is a range of compact, modular mains Gresham Lion are well known for. It shows in the switching power supplies designed to meet today's quality of every one of our extensive range of needs in terms of size, price, performance and reli- products. It shows in the continual testing being ability. Our latest 50W switching PSU, for example, undertaken by our Quality Assurance Department. offers remarkable value. Because, for just £70 you It shows in every transformer we make. It shows in get a unit offering efficiencies in excess of 70% the impressive reputation we have established for with line and load stability of 0.15%, temperature ourselves over the past 36 years. coefficient of 0.005%/°C and an operating tem- So, if you'd like to know more about the GRIPS perature range of —10° to + 70°C. Added to this, range, or about Gresham Lion products in general, fewer components means higher reliability than send for our Standard Product Catalogue simply by conventional linear power supplies. writing, ringing or circling the card at the back of This new unit complements an already impressive this publication. GRIPS range. Working from inputs of 250V, there Youl Ifind our service is designed for the 70's, too. are units giving outputs ranging between 5and 30V at 50, 150 and 300W. And every GRIPS unit is inherently safe, the 50W unit will even meet a4kV Gresham Lion Limited rms insulation test. Gresham House, Twickenham Road, Feltham, Care and attention to detail are features that Middx. TW13 6HA, Tel: 01-894 5511. Telex: 27419. TOMORROW'S SEMICONDUCTORS ARE HERE

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TRANSFER OUTPUT TRANSIENT POWER SUPPLY PACK. INPUT CHARACTERISTICS CHARACTERISTICS CHARACTERISTICS RESPONSE CHARACTERISTICS AGE FAMILY Se EIMI. 01 set Vohs> ElIss Qom,. EOM. Curren, In put Coen . term SO. Gm"... 01519 '''E: G1m TO. DESCRIPTION MAI 0UPIPY NUMOES 51o0e Pompon wpm .E. 1.,.• leanOrmIth Cu rem Roection COMMENTS 19,51 1.

25EC ?1..a'sn 0/75°C 2016 0/75.0 25116 One MO. nit; 005 '1087 r6rHe re r in% I'''' 55,, 0,0, 5.,, E,,,,,,05.,,,,..,, NP., u9PC,E, oyp nma No me/. 1YP Min min lyp m. /PP P/P /PM mIn m. NP .10, nea0a5 . QUIET 200 ISO tOO 050 025 xl, 205 ISIS RO RO ' 7 'E. - 'E lE 90 -- E -.- 1 .- ennener 'Zee'.

NO LOAD F.E.T. Input 80.2055 30' eo 66 105 I 0.6pA 05 10. 1 10 740 Iso 70 90 aa " . lo 1 10 2003 120 o.ale 8 70 90

F E.T. Ia... aa.aces Is' eo 65 1pA 1 0.5A 04 10 E 1 10 ,,, Boo 101r A 10 1 10 6,11) 35 - 4 6 70 90 ...... "--e- Ov.,e• ,--", en a • so, 0,,,,m .e.,. VERSATILE 1.10.2406 4 30 11 50 500 5 100 30 1 10 500 150K 74 100 46 1 10 1 26' - 600'" - 50 •E ' Te 48 8 74 00 _...... ,,-- ‘9

FAST He New Rag• 00-2505 4 93 10 125 500 20 100 SO 110 150 251( 74 90 12' 11D 1 10 300 500 1 20 1 30 033 e 8 7. 00 „,--• ••••-› S1.1.1.•111‘11>'Odterennal ,r ±10 Me Slew lame 101•2016 5 20 14 125 503 20 loo roc 1 10 7.5K 15K 74 90 12 G ' ho ocro local -too loo 025 4 e 74 .0

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BROADBAND' Gen. Nupoul WidaSenel NA.2605 o s 7 . 5 40 5 40 300 111 80K 1500 74 100 12' .' 1.1D -10 50 75 15 4 74 e ...)---- CCiretiliProlactee

Gen. Purpose VOW.. 144.2625 3 s 7 5 40 s 40 300 111 110K 15120 74 loo toe ' /.10 1 10 320 060 •2o _ 3 4 74 00 „...2--: ti, 's:.aecI' 'rrCimi.mProtenteal TO8 Um or Gain Cm urnennt Driver • POWER Cuomo 80000, NA2435 70 - 303 30pA 205,0 - - 2 045 005 8 !AO 1400 - 81.1Na _200 15 73 - 66 Howes enln Cuentrr L

HIGH VOLTAGE High Volose 009645 a 15 7 12 50 15 so 200 105 1000 200K 74 loo •'' s 4.5 74 so ;.----"',Ërte,•;r:.r.:.„¡.,

SPACE SA VINC ..., Mie, Perform.. RA-2055 2 8 7 50 303 2 1CO 20 "-la 200 400 74 100 II Ti, ,,e 30 80 to - , -,- ->--•-1 Vt.' ',V; `, ,2, ". l' 2 - ropa, Pettomnence 1014605 130 400 30 120 --155 0505 8 rIO lis - 60 4 8 5 65 80 ...He es a 4 ao - -,'''=t uAn'e.;.•1•‘•fl Onea 66. Parlommace 1.04525 es 2 4 130 400 30 120 75K 05011 80 90 el° a lo 400 '" - "•' " - ...< ,^.17....,=•:e---. 92 o Du.. Gen. Opp.. NA-4741 1 5 6.5 80 400 30 100 5 112 250 500 80 - 113 80 1. --"--a-

low Power IHI. Slew, 00.2706 I 5 7 5 70 25 40 200K I 1. II 22 121 A COOL ' VA 80 I00 - 10 20 15COA 8 •00 • K- re•i».5.re:ve.l2t 'Leer Pomp

PR OG RA MARL E 'Prpprimmable 11/1.7725 2 7 a .0 I 20 5 - aso 170K 74 eo - 'Io Is - - - 00 - 210u4 2509A LtGiv - • EAAEgX.;•,,,',1>Y„. 'E. '''. meat Vs • 159 Ism ISuA Duel Paememmetne 140.27 - " r 8 40 I 20 5 - aso 120K 74 00 - lip 16 - - - oe - 211>,_ 2500A ,t',,., • ual NA.2725 PRECISE 01101,130. Stan.. 1.10.2005 MAI 0.2 eo.,v 150oA 100.0 5090 5005A 103 1,0 10 . 2001 120 60 2 710 7 - 40 - 2.5 - 3.5 SO Iao le° '---'

tnade bena width 12/ A > 10 /31 1TYpit / 1/0 04. 1 151100 151 Unav Gem eenowoo on <9.0/ I Improved mn Ay t.ei.

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58 Electronic Engineering December 1976 Design considerations for optically coupled isolators

In this article Chris Williams describes the two basic opto isolator families and describes methods of obtaining the best results from these devices.

Opto -isolators fall into two basic fami- transistors. The 4371 device from small part of the total effective stray lies the phototransistor and the photo Hewlett-Packard for example is cmos capacitance due to packaging. It can be diode/transistor. In the phototransistor compatible on the output. reduced further by the addition of an an led emitter is optically coupled to a • The simplest most general purpose internal screen, (without screen com- phototransistor detector. The active device is asingle transistor amplifier. mon mode coupling capacitance 0,07 pF, area is the base of the transistor, the The 4360 series is specifically designed with screen common mode coupling size of which presents a large effective for ultra high speed digital operation. capacitance 0,007 pF). base-collector capacitance. This in- A range of isolators is shown in Analogue isolation expressed as com- herently restricts the device to low fre- Fig 1. mon mode rejection ratio (cmrr), is the quency operation. For data transmission The fundamental purpose of any ratio of the relative effects of the differ- greater than a few tens of kHz, the sec- isolator is to enhance in the output, ential mode voltage and common mode ond family of devices must be used. the ratio of differential mode to common voltage on the output current. In dB this For the photo-diode/transistor an mode signals. It should reduce the level reduces to common mode rejection led emitter is optically coupled to a of noise present in the output signal (cmr) pin photo-diode diffused into a sub- compared to that in the input signal by cmr = 20 log 10 (cmrr) dB strate. In the same substrate, a single virtue of having no common electrical CMRR is dependent on the common transistor, Darlington pair, or linear connection between input and output. mode coupling capacitance and the amplifier can be diffused. This design The two ways by which noise, or com- frequency of the common mode signal approach has several major advantages: mon mode signals can appear in the but is independent of isolator amplifier • The use of a fast photodiode with a output are by modulation of the gain (see Fig. 3). Attention to the graph separate transistor can reduce rise and (wanted) input signal current and stray shown in Fig. 3for any particular isola- fall times by as much as 4000 % capacitive coupling. tor should show whether the cmrr at any while still having an equivalent out- Modulation is a property of the ex- known frequency of noise or interference put stage voltage gain. ternal input circuitry and can be elimi- present in the input signal is great enough • Choice of amplifier stage gives flexi- nated, if necessary by correct impedance to prevent undue noise coupling to the bility of gain, speed and drive con- matching (Fig. 2). The parameter of the output. If the cmrr appears to be in- dition. The split Darlington system isolation which warrants close attention sufficient, then a superior device should allows a very high gain (400% min), is therefore the common mode coupling be used, or neutralisation employed. yet the output transistor can saturate capacitance. This capacitance is only a For most analogue applications the as low as 0,1 V for improved noise single transistor amplifier would be margin with ttl when compared with most suited since it offers the best com- high gain standard Darlington photo- Fig. I: (a) Split Darlington isolator has bination of gain, speed and low distor- moderate speed; (b) photodiode/transistor tion characteristics. The split Darlington Chris Williams is with Hewlett-Packard Ltd. allows high speed and high voltage gain. type whilst having a very much higher

1-4370

Fig. 1A.

Electronic Engineering December 1976 59 gain, has the disadvantage that the base also only works if the isolator output discharge can occur within isolation of the first transistor cannot be accessed, amplifiers are active. If both isolators are materials possessing microvoids. Due to thus preventing its incorporation into a driven to cut off or saturated by an non-homogeneous fields within the ma- closed loop feedback system for low ecm transient, they will not maintain a terial, the field across a microvoid can distortion operation. Additionally, be- differential response to edm. rise to a critical level at which local cause of the higher gain, the reduced Amplifier de-sensitisation is a simple discharge takes place. The resulting ions speed of the device prevents its use in defence to use against e.. The base locally degrade the insulation. The amplifiers above 1MHz bandwidth. bypass resistor Abe reduces the impe- cumulative effect over time is to reduce The cmrr of the single transistor isola- dance in which the ecm transient, coupled the terminal to terminal breakdown tion can be improved by the addition of a via C., causes a current flow. So a voltage. neutralising capacitor between the tran- larger eorn transient can be tolerated. By using sophisticated detection sistor collector and either of the input It also reduces the amplifiers sensitivity equipment, such discharges can be detec- pins (Fig. 4). The value of the capacitor to photocurrent generated by the wanted ted when applied voltage exceeds a is set by:— signal, and requires a higher current in threshold level, the corona inception C = 3x cm -= 7pF the input diode for an on condition. voltage (civ). To maintain their insula- where [3 is the isolator amp gain. The base bypass can be used with either tion quality some isolators are built This capacitor should have a voltage single transistor or split Darlington iso- using a"back filling" system that forces rating compatible with the application. lators, and has the added benefit of a silicone oil under pressure to fill any Neutralisation can be employed with higher data rate capability. 11.k is microvoids. This results in the civ being dual versions of this isolator provided recommended for protection of the well above the rated Vi_o. each capacitor coupled the collector to isolator if large e. transient (static The main properties of insulation are its respective input diode. electricity discharge) may be exposed to breakdown, voltage and leakage resis- the effective common mode coupling tance. In some isolators leakage re- Digital operation capacitance. sistance of the order of 10' 2 leads to a Digital operation requires that the Use of high cmr devices encompass typical leakage current of only 3nA output remain in proper logic stage des- two types, either addition of internal when subjected to the 3000 Vdc max pite the interference from Corn. This screen to existing type of isolator or rating for Vi_o. If performance superior ecm can be in the form of sinusoidal or using isolator with fibre optic medium to this is required, the more expensive transient so, two different measuring to reduce eorn even further. For optimum fibre optic devices, with greater physical systems are necessary to evaluate an performance of cmr, the board layout of separation between emitter and detector isolator response. Detailed description isolators should be such as to separate must be employed. of such measurement is given by refs the input and output leads physically. 1, 2 and 3. A digital system cmr can be A small ground trace under the isolator Speed of response enhanced in the following ways (Fig between input and output leads will also For analogue and digital operation, 5): improve cmr performance. speed of response is a function of the • Neutralisation external circuitry as well as isolator • Balanced differential amplification Insulation techniques characteristics. In both types of system, e Amplifier de-sensitisation Many designers unaware of corona or the speed, can be improved by feedback • Use of high cmr devices its effect assume insulation can be or peaking. As for analogue isolations, neutra- operated at any voltage up to the break- Analogue operation requires the lisation can be used for single transistor down voltage. Others may assume that isolator to remain in its active region amplifier isolators. It is effective only corona occurs only at the exposed (no cut off or saturation). Speed of when the transistor is active, not satura- terminal pins. In fact, corona, or partial response is characterised in terms of ted or cut off. However, since it is while 10%-90% rise time if input signal is a the transistor is active that ee m can cause Fig. 2: Modulation circuitry external to step function, or 3dB bandwidth if the most problems it is worth while trying the isolator must be matched. input signal is asine wave. this solution. Fig. 3: Typical sinusoidal common mode The principal bandwidth limiting Balanced differential amplification rejection curve. elements are the photo emitter, the

60 Electronic Engineering December 1978 amplifying transistor, and the capaci- Fig. 4: CMR improved by the addition of • In a high speed system, the isolator tance of the photodiode. The base time a 7pF neutralising capacitor from output may need to be decoupled to prevent constant of asingle transistor isolator in collector to input. internal oscillation which would degrade common emitter mode is given by:— performance. This decoupling is effected = RB(Cro -}- CBC) PRLCBc (1). to switch from one logic state to another. by having a 0,01 1../.F ceramic capacitor where CPD -= 10 pF = photo diode For the low condition, IFshould be large between Veeand ground, as close to the capacitance CBC is base to collector enough to bring V well below some de- device as possible. To optimise per- capacitance plus stray external capaci- fined threshold, and for the high con- formance, this capacitor should be lo- tance between collector and base condition, IF should be low enough for cated so as to minimise the coupling of nections, RL is the load resistance and Vc to rise well above threshold. Speed of noise generated by the isolator lead into RB is the dynamic resistance to ground response is defined as the time required Vee and ground of the isolator. at base. With no base bypass resistance. for Vc to reach the threshold in re- Substituting typical values for such an sponse to a change of logic state at the isolator gives:— input. Characterisation is either in Reverse coupling The high leakage resistance of opto TB = PCBC(RL + 175n) (2) terms of propagation delay or data rate, This shows the importance of having a where propagation delay is the time for isolators (-=•ioi2n) virtually eliminates low CBc. (CBC for photodiode/transistor a change of logic state to propagate DC ground loops. Internal capacitance combination is typically 0,5 pF for a through the isolator and cause achange allows AC ground loops to flow accord- phototransistor it is typically 20 pF. of state in the load. There are two values, ing to Also the base time constant is only one for low to high transistor at the de em limited by RL if RL >175n. output, trim, and one for high to /ow, IcL where Ci_o = input Use of feedback to reduce 13 can also tPHL• improve the speed. A typical ac amplifier to output capacitance circuit is shown in Fig. 5. Note that the Isolator influences input current is peaked for maximum Isolator characteristics influence trim Note that Ci_o is a function of packag- speed response with the dynamic range and trim but propagation delay is also ing; it is much larger than Corn and is limited for low distortion characteristics. contracted by the external circuitry. effectively independent of whether an The bandwidth of single isolators Raising IF reduces trim by causing large internal screen is fitted or not. may be improved by clipping the base collector current but raises trim by There are no circuit techniques by lead if not required. This reduces the causing the output to be deeply saturated, which Ci_o can be reduced. In applica- stray capacitance element of CBC. If thus increasing the storage time. tions where Ci_o (1 pF) is too high, a several circuits are in close proximity the Raising the value of RLoAD also re- device incorporating greater physical use of dual isolators is recommended duces trHL by reducing the current separation from input to output must since the base is not brought out to an it sources to the Vc node, but this in be used. With Ci_o = 1pF, the ground external terminal. The base rise time turn raises trim by reducing the current loop current that flows from a 50 Hz, equation shows why the high gain of the available ro pull Vc up again. eem is only 520 pA per volt rms. split Darlington type of isolator results For any application, a device with in areduced speed response. This and the better propagation delay characteristics inacessibility of the first transistor base is to be preferred to squeezing the last Forward coupling for full feedback reduces its attraction microsecond from a slower device. In analogue systems, forward coupling for low distortion analogue usage. Speed enhancement techniques usually is simply gain and is specified as current It should be noted that when feed- degrade the cmr, so the advantage you transfer ratio (ctr). For digital systems, back is used with the single transistor gain on the speed you may immediately it is more useful to consider it in terms of type, the base lead is needed to provide lose on having reduced raise immunity. fan out capability. CTR is not constant a trade off between bandwidth and dis- The fastest devices available can for all levels of input current. This is tortion improvement due to feedback handle data rates up to 20M/bits. This largely due to the change in gain and bandwidth improvement because of speed is gained by having an integrated (hi e)of the output amplifier, especially if the reduction of stray capacitance (base linear amplifier, and Schottky clamped it has more than one transistor. This is lead). Both techniques should be con- output state. The linear amp does not plotted by giving either output current sidered before deciding on one for the saturate at either logic level, and is or ctr as afunction of input current. final circuit. maximised for speed response with the It is an inevitable fact that light out- Digital operation requires the isolator photodiode. put from an led degrades slowly with •

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64 Electronic Engineering December 1976 Failure mechanisms in COSIMOS integrated circuits

This article discusses the reasons why failures occur in integrated circuits fabricated in cos/mos technologies. Gal/ace and Pujol explain how some of these failures may be avoided

As ameasure of reliability of COS/MOS because all of the current is concen- that cause inoperability in system use, integrated circuits, test programmes trated in that area. or dramatic changes in performance must evaluate the known or expected There are other modes of failures during high-stress testing. failure mechanisms. These mechanisms related to basic processing problems. can be determined by proper reliability In the semiconductor industry, failure Basic failures may mean anything from acatastrophic programmes which intelligently use Regardless of complexity, the basic inoperable condition after some period accelerated tests. Supplementing these failures occur within small cells, com- of use to some minor cosmetic defect tests should be careful analysis of field posed exclusively of mos transistors and failures when they occur. that bothers a customer who is con- mos loads, with an occasional diffused cerned with the overall quality of the The pie chart in Fig. 1 shows the resistor or mos capacitor. The most obvi- product he is buying. This discussion mechanisms that normally occur in field ous and important mode of failure is an of failures is confined to problems failures. Over-current and elongated open circuit. This open circuit could types of failures predominate. About occur within the mos device or in the 50% of all devices analysed are found conductive interconnect that leads to the to have failed as aresult of electrostatic device. If the device is totally operable lamage, overstress, and/or application- at the time of shipment, an open circuit related problems. can only be caused by excessive current In order to detect electrostatic density or abreak caused by thermal or damage, normally a curve-tracer check mechanical shock. Mechanical shock is is made. The area in question has to be more likely to cause an open circuit when isolated by electrical test. For example, if the pellet is joined to the package by agate oxide is shorted, it will show up as fine wire bonded by thermal-compression a high input leakage (positive) varying or ultrasonic techniques. One of the in magnitude depending on how bad most damaging environments is the the short is or how marginal the break. ultrasonic cleaning commonly used for A degradation of some other parameters, flux removal from printed-circuit boards. such as noise immunity, functional The short circuit is the second obvious capability, output drive, or diode symptom that is caused by innumerable check may also be seen. failure modes. There are probably more An overstress failure is seen internally types of short circuits or partial short as a burned or open metallisation path. circuits than there are types of open Fig. 2 is a photomicrograph showing Fig. 1: Mechanisms that normally occur in field failures. circuits. A short circuit may be caused metallisation as a result of current by the following: 8 Fig. 2: Photomicrograph showing overstress in the V. line of a cmos 6Contaminants between two con- metallisation as aresult of current over- device. An SCR-type latch failure is ductive areas of different potential. stress in the Vss line of a cmos device. always seen as V.s burned metallisation • Metal deposition. Faults in the LJ Gallace and H L Pujol are with RCA Solid Fig. 3: SEM photomicrograph of a photoresist or in the actual metal- State, Somerville, NJ, USA ruptured gate oxide. defining mask may cause a bridging

continued on page 67

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66 Electronic Engineering December 1976 which can be detected optically and Fig. 4: Examples of gate-oxide rupture By far the greatest number of gate should not be a significant field failure on a p-channel device and an shorts occur when excessive voltages are mode. n-channel device. directly connected to external terminals; •Liquid contaminants left on the Fig. 5: Gate oxide rupture points in a this fact indicates the inability of pro- surface as a result of poor cleaning perfect mos transistor tective circuits to function with 100% procedures. reliability under all conditions. 111Surface short circuits may also be caused by metallic particles. Common Moving ionic charges pre-form material used for soldering the Another mos failure mode is the pellet to the package is asource of small threshold drift phenomenon caused by pieces of conductive material. Ex- the presence of ions under gate struc- traneous bonding wires are similarly tures. Because positive ions are more dangerous and are not easily detectable likely than negative ones, most con- after the package is sealed. taminations are caused by sodium ions. •The degree to which the surface Another problem related to ionic metal is alloyed with the base silicon is contamination is surface contamination, a subject of much discussion. Over- which may cause leakage between source alloying is dangerous; it can lead to and drain. The threshold voltage may short circuits. appear to be low, which is likely to •Ruptured oxide causes a short seriously reduce the noise immunity of circuit between the surface metallisation the device. and the substrate material. Movable ionic charges in the thermal oxide can reduce or increase threshold Gate-oxide shorts voltages, depending on the ionic charge This failure mode is probably the and the type of device (n- or p-channel) most common for mos devices. It can affected. Sodium ions (-0 in the thermal be caused by customer mishandling, oxide of n-channel devices seem to be manufacturing defects, or acombination rupture the gate oxide should have the the most difficult to control. Although of both. Essentially, the basic cause is rupture points located at one or more of very clean gate oxides are grown, most overstress of the gate oxide by the four corners of the gate area, or along sodium ions tend to move in from the application of excessive voltages either the periphery of the gate diffusions, as field oxide. directly (ie application of excessive shown in Fig. 5. Such rupture would Figure 6 illustrates a thermal oxide external voltage spikes or signals directly occur because the electric field at these with positive-ion sites randomly dis- to gate oxides at input terminals and/or points is higher than at the edges. tributed throughout because of natural power terminals) or indirectly (je In practice, however, voltages greatly diffusion at room temperature (290°K). internal gate oxides stressed by VDD in excess of puncture threshold might Although these sites have some effect on and signal voltages not directly accessible cause one or more corners to short- the initial threshold, compensation from external package leads). The term circuit and, in addition, may puncture a can be introduced by variation of oxide excessive refers to voltages too high for weak spot elsewhere (not necessarily a thickness in manufacture if the concen- the existing oxide conditions and protec- defect point) because of the quantity of tration of ions is known and controlled. tion networks. charge available and the amount of over- As soon as bias is applied to the gate COSIMOS units are subjected to voltage applied. Normally, the p- metal, however, ions begin to move as a many applications in which excessive channel devices are more sensitive to result of electric field forces. The charges above-rating voltages, both d.c. and gate oxide shorts because the gate oxide finally relocate as shown in Fig. 7, where spike, cause oxide rupture. This type of is thinner than on n-channel devices. the positively charged gate has pushed problem is probably easier to resolve and Devices with the short-circuit locations the majority of positive ions under the Fig. 3shows a scanning-electron-micro- shown in Fig. 5 (more than one unit metal toward the silicon-thermal oxide scope photomicrograph of a ruptured sample) may have non-homogenous interface. This concentration is sufficient gate oxide. Fig. 4 shows examples of oxide problems, oxide pinholes or sili- to reduce the threshold voltage, and gate-oxide rupture on a p-channel con hills, which could cause premature may be enough to cause the new n-chan- device and an n-channel device (arrows rupture. These defects can sometimes nel to remain after the gate bias is with- point to rupture). Theoretically, a be visually observed after the gate drawn, forming a permanent channel perfect mos transistor overstressed to metal is removed. from nto n(source to drain). The rate at continued on page 69

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68 Electronic Engineering December 1976 which ions are driven into this condition content in thermal oxides also apply to ion movement. Gates are normally «is proportional to the silicon dioxide negative-ion contamination except that biased with their on polarities, and the temperature and the gate voltage. When the results for p-channel and n-channel resulting changes in threshold voltage in- gate bias is removed, ions begin to diffuse units are reversed. However, negative- dicate what type of ion contamination and revert to initial conditions. ion content is easier to control in pro- is present. HTRB tests are preferred to If anegative polarity is applied to the cessing and is not a major factor in ac operating life tests for detecting ionic gate metal, then a transverse field is leakage failures. -problems. In ac testing, gates that are established which sweeps the positive Life tests to check for the presence of operated at, for example, 50% duty ions into the gate oxide, when accumu- contamination are varied. The most cycle, allow time for diffusion of ions lation take place. This mode of operation effective seems to be HTRB (high- between pulses at rates equal to that for can cause an increase in leakage failure temperature, reverse-bias), where gate recovery at the life-test temperature. As of eight times as compared to the posi- voltages are d.c. (100% duty cycle) and a result, devices having low levels of tive gate polarity. temperatures are elevated to speed up contamination may not drift enough to When positive-ion concentrations are be failures. HTRB tests, however, would high, or high voltages are used in mos Fig. 9: Equivalent diode circuit charac- cause these devices to fail. Worst-case units, field inversion (p-layer inversion teristics for ap-channel device without conditions should be used because the under field oxide) can occur, causing protection. device could be subjected to dc bias in formation of parasitic mos devices field use. and resulting in unwanted coupling of two or more circuits together, as shown in Fig. 7. It is thus necessary to install Diode leakage channel stoppers between adjacent A COS/MOS device consists essenti- devices in the form of extra diffusions to ally of diode areas diffused into a prevent unwanted current paths. When substrate. Fig. 9 shows an equivalent n-type substrates are used, separate diode circuit characteristic for a p- p-type wells or guard rings can be used channel device without protection. The for each device as channel stoppers, as diodes shown are capable of exhibiting shown in Fig. 8. all the characteristics of ordinary diodes. Localised contamination at the silicon- Complementary devices dioxide silicon interface can cause COS/MOS units use complementary degraded reverse diode characteristics, n-channel and p-channel devices on the which result in degraded device per- same substrate. In the case of an n-chan- formance. nel device, positive ions cause permanent 13,, degradation, where By, becomes inversion of the p-type well. When the Fig. 6: Thermal oxide with positive-ion less than VDD is troublesome in complex gate is negative with respect to the sub- sites randomly distributed throughout. circuits. A soft reverse B, characteristic strate, positive ions are driven in a also reduces the load impedance at the direction which tends slightly to increase Fig. 7: Relocation of charges after drain or source, and can change the the threshold voltage above that for application of bias to gate metal. gain or digital logic levels. Poor Bvi- can normally dispersed ions. Fig. 8: Guard rings used as channel also be attributed to defects in the Comments that apply to positive-ion stoppers in n-type substrates. silicon bulk material.

Direction of field +Gate Gate Gate metal Cross- iThermal section . + oxide + + Gaie :metal + + view Thermal .1. + + \n \ ocid +++ + -F + + + + + +

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Digital logic board design with test heeds in mind

With the growth in the variety, complexity and use of digital logic integrated circuits over the past few years, the need for ensuring the testability of digital systems has become more and more critical writes David Tose

Printed circuit assemblies today contain and never exceed the rated fan out. ment, but for a single pcb it is easy to vast quantities of electronic circuitry, • Do not use (or use the minimum overlook circuit initialisation. shrunk by modern technology to afrac- of) 'select on test components'. Figure 1 shows a frequently used tion of the size required by their prede- • Avoid the use of one shots if possible, divide by four counter for generating cessors. The reliability of these devices though if used do not route their internal clock phases. The counter and consequent assemblies is very high signals via the edge connector. runs continuously as long as the inhibit but, when afault exists within the circuit • Provide adequate decoupling, both at line is held /ow, but when the inhibit assembly, the problem of fault isolation the board edge and locally at each ic. line goes high the counter continues to is avery real one. • Use a single large edge connector if run until it is back to acount zero state. Economics invariably influence the possible, and provide test/control It is therefore self-initialising. design layouts of pcb's and unfor- points via this connector in addition However, the circuit has two problems tunately, the problems of testability to the normal input/output control from the viewpoint of being suitable for rarely cross the mind of the design signals. automatic testing. First, several clock engineer at the initial stage. However, • Where signals leave the pcb, provide pulses will be required to initialise the just keeping to a few basic rules at the them with the maximum fan out logic at switch on, and this number will time of design can result in rewards drive, or buffer them. vary from zero to three. As the number during the production phase of a pro- • Where signals enter the pcb load of divide by two networks is increased, duct's life cycle. them with only one load if possible. the number of initialisation clocks will It should always be remembered that • Buffer edge-sensitive components also increase, logarithmically. Secondly, even if pc boards have not been designed from the edge connector (eg clock if a fault exists in the initialisation, with ATE (automatic test equipment) in lines, Q and (j. flip flop outputs). then the circuit may never initialise and mind, they can still be tested by such •Terminate unused inputs with a such a fault in a feedback network of equipment. The point is that a lot of resistive pull up to minimum noise this sort is difficult to diagnose since it is time and money can be saved, and pick-up. not always repeatable. frustrations avoided, if the speed and • Keep complex logic functions divided If the circuit were changed to that of board throughput rates possible using up into smaller combinational logic Figure 2, then automatic testing would ATE are considered at the outset. sections by proper board layout. be much simpler. In this version of the It is the ease with which a board can In addition to these general design divide by four circuit, the reset line be tested and faults isolated, that should suggestions, there are other features is brought out to the edge connector, be one of the design engineer's major which can be easily incorporated at the thus enabling asingle pulse initialisation. criteria. He must accept that when a time of layout and which will enable In the system, the reset line can be left pcb comes off a production line there is the board to be automatically tested unconnected in the back panel wiring. a strong probability that it may not more simply. For example, keep the work. If the assumption is made that logic depth on any pcb to alow level—if Chains and loops • the production board is certain to be necessary, by using edge terminated Long logic chains often take many good, and its testability is neglected at test and control points. Utilise test pulses or operations to provide output the design stage, then problems will points, routed to the edge connector, to changes, and so their test time is long. arise. enable monitoring and control of the If long chains are broken via the edge This article is intended to provide internal board functions and to assist in connector however, the test programme some guidelines on improving testability fault diagnosis. And do not use high can be written to treat the short chains and reducing test bottlenecks of which fan out logic devices on the board, but as individual circuits, and can often design engineers are often unaware since use multiple normal fan out devices and test them at the same time. The circuit the problem is unfortunately experienced keep their outputs separate. interrogation becomes more straight- by the production test department after These precautions can be supple- forward and fault diagnosis from the the design phase has been completed. mented by the test programmer at the edge connector is easier. software design stage by keeping test Logic loops, like chains, are also General Considerations sequences as short as possible (using difficult to test, because the source of the The different types of test procedure are parallel test techniques if appropriate), fault is hidden by the loop. If the loop is many and varied, but they divide into avoiding operator intervention wherever broken or at least capable of being four main groups, namely goods in- possible, and using automatic fault iso- over-ridden at the connector, then the wards, assembly visuals, functional and lation techniques when practical, to source of the fault can be located. fully dynamic. They all have their merits speed up the test and fault isolate modes. The logic loop shown in Figure 3could and complement one another; this be reconfigured as shown in Figures 4 article however will consider only aspects and 5. In Figure 3, an earth at A, B or of functional circuit testing. Initialising the logic C will lock up the function, whereas in At the pcb design stage many tech- At this stage in the pcb design, Figure 4 the feedback loop has been niques can be applied to assist testability external reset controls should be pro- broken, point D has now become a and general rules are listed here: vided for all memory elements on the circuit monitor point, whilst E is avail- • Keep logic fan outs to a minimum, pcb. Counters, shift registers and se- able for signal injection. By adopting David Tose is with Industrial Products Division, quential logic are normally self-initia- the circuit in Figure 5, the logic loop CAI Ltd. Esing when used in a systems environ- can be over-ridden by use of point D.

Electronic Engineering December 1976 73 One shots are best forgotten. They are difficult to test with any equipment, noise prone and are often only used as a design get out. When they are cascaded, the problems snowball and there is no way that the overall logic sequence can be slowed down to assist fault diagnosis. Fully clock-synchronised systems have no such problems. In the event that one shot insertion is unavoidable, the following points should be borne in mind: use one shots with a dc reset capability; provide a means of external over ride control; and use one shots with time periods of not less than a few hundred nanoseconds. When free running oscillators are used, a means of external over-riding should be provided as shown in Figures 6and 7. The circuit in Figure 6allows the oscillator to be over-ridden by A and an external clock to take its place via B. The circuit shown in Figure 7, which is normally connected between A and B via the back wiring, enables the use of an external oscillator for stimulus synchronisation. Oscillators of this nature should be located near the board edge connector to enable simple over-ride control and minimise signal crosstalk. Elements in some logic families allow the use of common output stringing to make up wired and or or gates. This is possible because the logic elements only have an active pull down circuit, pull up normally being achieved by a resistor which is either internal or external to the logic function. This practice, although economic in terms of logic usage for the design engineer, creates problems for fault diagnosis because the fault source can be one of several logic elements. An additional summing gate should be used instead of the wired configuration; Figure 8illustrates this point. When this is not practical, gates in the same integrated circuit package should be utilised since this can greatly reduce the number of ic replacements. The more test/control points that are available on aprinted circuit board and the better they are sited, the more comprehensive will be the test and more accurate and faster will be the fault diagnosis, resulting in greater throughput. Control points can be employed as test injection points to provide either an extra external reset capability, or perhaps over-ride signal injection. They can also be particularly useful at logic junctions where large numbers of inputs or outputs converge. If the master edge connector does not have sufficient pins available for test points, then it is worth considering the use of an additional connector at the other end of the board in order to provide these points. Integrated circuit clips can be employed to supplement I/O pins, but their advantage is dubious because they increase board connection time considerably and impede guided fault isolation techniques. As a general rule, the ratio of input/output pins to number of inte-

74 Electronic Engineering December 1976 ..--weerre nt 7,7

grated circuits should ideally be 2:1. A ratio of less than 1:1 should be avoided. Other design factors to bear in mind are as follows: eDo not terminate logic outputs directly into transistor bases; use a current limiting resistor instead. • Buffer flip ¡flop output signals before they leave the pcb. • Do not hardwire the pcb's into the system but use only one large connector if possible. • Avoid the use of potentiometers. • Make pcb input and output signals ttl compatible whenever possible since this keeps automatic test equipment interface costs low and gives greater flexibility. •Where d-to-a conversions take place, bring out test points as near to the conversion point as possible. e Use free collector devices with pull up resistors, since these enable external over-ride control. • Allow sufficient room adjacent to each ic to attach atest clip. • Standardise on power and earth pins to avoid a multiplicity of test harnesses. • If the pcb uses complex integrated logic such as cpu's, long dynamic shift registers or uarts (universal asynchronous receiver/transmitters), mount these devices in ic sockets in order to a) facilitate their simple replacement in the event of failure and b) enable the board to be tested prior to the insertion of the device at the end of the production line. This also has the advantage of allowing simpler automatic test programmes to be written. • Provide linked pins at the edge connector end of the pcb to enable the tester to check the pcb's correct insertion. These pins can be coded to provide a unique address, recog- nisable by the tester, which can iden- tify the board type or variant prior to applying the unit under test power. • If lamps or displays are mounted on the pcb, route their logic drives to the edge connector so that the tester can check for correct operation. • Unit under test mounted switches cannot be operated by the tester, and manual intervention slows down throughput rate; so route switch output lines to the edge connector to enable external over-ride (Figure 9). • RC networks are often employed as a power up reset for memory logic. Because these circuits are of limited use to the tester, an over-ride line to such circuits should be provided. If the points discussed above in this article are heeded, the initial design costs of aproduct might increase slightly. But such an increase will quickly be re- couped during the product's life in terms of quicker, more comprehensive and reliable testing, easier re-working and simpler modification.

Electronic Engineering December 1976 , 76 • 62 on enquiry card For high performance receiver testing, you need high performance signals.

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El trin I TIO111e RREOUENCT 1.21(11er. TONilli". • J

HP 8640B w/Opt. 001,002, 003 —0.5 to 1024 MHz.

When HP introduced the 8640B, its product con- Now with the 8640B you get /12 digit phase-lock cept brought together the superior characteristics resolution (500 Hz, 100 to 1000 MHz), improved needed for high performance receiver testing: modulation and power settability. You can also use the new Mode111710A Down Converter to •Spectral purity <130 dB/Hz, 20 kHz offset extend outpùt frequency down to 5kHz and test •Wide dynamic range; +19 to —145 dBm standard IF amplifiers at 262 kHz and 455 kHz. •Phase lock stability/external count capability So for your high performance receiver testing, Since then we've continued to add to the original you'll still choose the performance leader in RF capabilities: signal generators. For more information, contact your local HP sales office. • Opt. 001—Variable modulation •Opt. 002_ Extended frequency, 0.5 to 1024 MHz •Opt. 003_Reverse power protection to 50 watts HEWLETT PACKARD •Opt. 004_ Avionics version for NAV/COM tests Sales and service from 172 offices in 65 countries. •8640M_Ruggedized/military version Winnersh, Wokingham, Berks RG11 5AR Tel: Wokingham 784774.

76 Electronic Engineering December 1976 Advances in medical electronics

There are several interesting developments in the medical electronics field. The use of lasers and ultrasonics provides both powerful diagnostic and treatment facilities writes Elaine Williams

The use of electronics in many areas of certain if the brain is starved of oxygen to be a very powerful measurement medicine has increased dramatically for more than four minutes. diagnostic tool and its probes are over recent years. Today electronics is Measuring the electrical activity of external and therefore non-invasive. used not only in aresearch environment the heart is performed by measuring Also it overcomes the obvious dangers but in practical situations such as potentials at the surface of the body. associated with x-rays. The main limita- patient monitoring systems and diag- Any variation from the normal rhythm tions of this technique are that bone nostic equipment. Although we are still is known as arrhythmia. It is for this and gases strongly affect high fre- a long way from the bionic age, reason that patient monitoring systems quency sound waves so interfering with electronics has made a considerable have become popular over recent times. transmission through certain 'areas of contribution to the study and treatment These systems can not only measure all the body such as the lungs, skull and of awide range of diseases and abnor- the important body parameters but gastrointestinal track. mal conditions. monitor several patients simultaneously. Ultrasound is generated by a trans- The understanding of the workings of Most of these measurements are made ducer made of piezzoelectric material body functions which exhibit electric- externally by probes and internally by in a probe. The material vibrates at high ally measurable phenomena such as the catheters so that EEG, ECG, arrthyth- frequency when a pulse of electricity heart and brain have particularly mia detection, pulmonary artery pres- is applied. Normally ultrasound is profited from the electronics engineer. sure and arterial blood pressure can be considered to be above 20 kHz but a The brain has been one of the first determined. working figure of above 100 kHz is areas to be studied in this way since it Transducers are extensively used in commonly employed. As high fre- is the most active area in electrical medical measurements. Transducers are quency sound does not travel well in terms and, for so many years defied any either attached internally or externally. air the transducer must be coupled to other type of investigation. Most It is more desirable to have probes the body by a liquid. measurements concerning the activity externally fitted since this causes less Applications for this technique are in of the brain are grouped under the discomfort to the subject but makes obstetrics and gynaecology and the term electroencephalography. • readings more susceptible to the very Doppler effect is used from the measure- Normally measurements are recorded noisy environment of the body. Blood ment of arterial blood flow and veloci- from electrodes placed on the scalp flow is measured by placing a mean ties. Ultrasound also has an interesting although some relatively rare diagnostic velocity transducer in an artery having a role to play in the treatment of tumours. procedures require electrodes on or known cross sectional area. The most It can destroy or shrink tumours by beneath the cerebral cortex (which is common type of these transducers . is applying heat to cancer cells. These the outer layer of grey matter of the the electromagnetic type which con- cells are apparently more susceptible brain). The electroencephalograph sists of an electromagnet to generate a to high temperatures than healthy ones. commonly known as the EEG has been magnetic field and two electrodes to Heat is focussed on the tissue by the known for some 40 years and is sense the flow signal. They are encap- sound which raises the temperature of especially useful in the study of sulated in epoxy in a form to allow the cells to about 180 °F. There has also epilepsy. Although there are several them to fit around the blood vessel. been evidence to suggest that treat- forms of epilepsy the EEG waveforms In some areas of medicine, ultra- ment by ultrasound may increase the can give an indication of the type and sonics can overcome the problem of sensitivity of these cells to further this outlines the treatment to be internal probes. Ultrasonics is proving •treatment by x-rays or drugs. Methods undertaken. are also being developed to monitor The two electrodes of the pain con- Also the study of EEG has been internal temperatures to control the troller are fitted so that the affected known to help in the detection of brain ultrasound dosage. area is situated between them. tumours since they alter the normal Another device which has found brain patterns by showing a lack of some application in the treatment of organised electrical activity in the tumours and other malignant growths region of the tumour. This is limited is the laser although, by far its largest however because of the variability in use is in the area of eye surgery. the response between tumours of However its use will never assume the different types. same proportions or impact that x-rays have had on medicine although it does Sensitive indicator have a significant contribution to make The EEG is a very sensitive indicator in the area of eye treatment. of the state of awareness of the brain Experiments have been going on in since the patterns generated during the use of pulsed solid state lasers in the various activities are markedly different. treatment of skin cancers (melonomas) Another application in which this with some success as has the use of a measurement has proved valuable is CO, laser knife for surgical purposes for monitoring patient activity during where there is a high concentration of surgery involving the heart. Should the blood vessels (highly vascular areas). heart stop for any length of time cerebral Eye surgery utilises the laser largely monitoring equipment can determine for repairing detached retinas. If the the extent of brain damage if any, since retina becomes detached from the it is generally agreed that the likelihood choroid or some part of it, blind spots of permanent anoxic damage is almost occur. By flattening the retina against

Electronic Engineering December 1976 77 64 on enquiry card Picofuse the smallest thing 5miniature Picofuses were built into the circuits of Surveyor 3-the spacecraft which sent back to earth OFF earth so much information about the surface of the moon. A project such as this demanded the very best in electronic equipment protection which is why NASA called in Littelfuse. Itt the LITTEL things Picofuse,the smallest fuse available, that keep the big things going. is the ultimate answer to your requirements for so many, more e> down-to-earth applications.

LITTELFUSEMDIMEMED CROWTHER, DISTRICT 3, WASHINGTON, TYNE &WEAR NE38 OAB, ENGLAND. TEL: 0632 462479. TELEX 537095

UK Distributors:— WOOLLEY COMPONENTS LTD., 214A Manchester Road Broadheath, Altrincharn, Cheshire W14 5LU Tel. 061 928 2289/7425 Telex 669735 THE RADIO RESISTOR CO. LTD., P.O. Box 12, 4 Trust Industrial Estate, Wilbury Way, Hitchin, Hertz SG4 OTN Tel. 0462 54077 Telex 826251

65 on enquiry card At+125°C you can burn your fingers on some DAC's

. 4 wafflit. im our 4058 stays cool

Because this new, hybrid 12 bit DAC was specifically designed for the temperature range —55 to +125°C. It is not merely a top-end selection of commercial DAC's, where you don't know today what tomorrow's yield will be. Your application may not need the full temperature range nor the hermetically sealed metal DIP. But for alot of industrial applications these and other features of the new DAC offer you vital safety factors. For example, it is produced to IL Std 883 giving extremely high reliability. It has a very low temperature drift of 5 ppm/°C gain, 10 ppm/°C max. offset. And if you want to fly with it, the 4058 is shock, vibration and acceleration tested -its already being used in the new MRCA.

Heathrow House, Bath Rd, Cranford, Middx. Tel :(01) 897 2501 • irTELEDYNE PHILBRICK Telex 935008

78 Electronic Engineering December 1976 1111.,

the choroid (which is a vascular and to ensure that sufficient stimulating severe pain after an operation or ill- pigmented membrane extending around current passes directly to the heart. ness (post herpetic pain). the back of the eye) it is sometimes This can mean that the subject may Melzack and Wall suggested that by possible to re-attach the retina. Even if experience a significant amount of exciting the myelinated cutaneous this cannot be achieved the detached pain. fibres this would reduce the effect of an area should be sealed off to prevent the The study of pain or rather the control input via the small myelinated fibres. retina becoming totally removed from of it is an extremely fascinating area of Since the activity of some of these the choroid. medicine. Since pain varies so much small nerve fibres causes pain, the effect The basic principle is to produce a between individuals and, cannot be of the excitation might diminish the localised welding of the retina and measured accurately in any way, it effect of pain. choroid. There are several techniques becomes an interesting but frustrating The treatment itself consists of which exist such as diathermy, cryo- problem. In some cases patients may electrical stimulation of the affected surgery and the xenon arc coagulator. be in continuous pain after an operation pain areas by the use of two large The coagulator for example requires or illness. Post operative pain is a electrodes which are placed on the that the patient is anaesthetized so common phenomenon and often dis- skin near the affected parts. The intro- that the eye can be immobilised because appears with time but sometimes it does duction of a small electrical signal in an exposure of several seconds is not. Also illnesses such as shingles effect overrides the signal to the brain needed. However, a ruby laser pulse which attack the nerves may cause which the pain provides, hopefully lasts about 1 ms so there is no need to continuous pain even after the virus has reducing the overall effect. provide immobilisation and the opera- been destroyed. There have been several studies made tion may be provided in the outpatient Until recently the only way of easing on the effectiveness of such treatment department. the pain has been through the use of and they have concluded that pain More down to earth techniques are drugs or anasthetising the affected relief was possible by use of such also applied in medical electronics such areas but obviously this is not very treatment which is commonly known as the use of thick film hybrids in heart desirable in the long term but neither as transcutaneous electrical stimulation. pacemakers. These devices are pro- is the prospect of pain. Some work has In one study the figure showed that duced in hermetically sealed packages been going on in electronics to control 77 per cent of subjects using this and are placed in the abdomen to the level of pain in these patients and method benefited from some pain avoid tissue irritation and rejection. some encouraging results have been relief. • Connection to the heart is then made by noted. Although there are few areas left cardiac catheter or electrode. The principle by which the pain in medicine where the use of elec- There are currently three types of controller works can be explained by tronics has not been investigated pacemaker available which are intern- the analogy that to relieve toothache there is still room for considerable im- ally fitted. These vary in price from about one bangs one's head against a brick- provement. On the one hand we see £300 to £2000. The least expensive of wall ie to lessen the effect of pain one highly sophisticated equipment such as the internal pacemaker (which is diverts attention by introducing another patient monitoring systems (and it will really a signal generator delivering 71 stronger signal. This principle is not be too long before some of this beats per second) uses a mercury cell embodied in the gate control theory equipment will be microprocessor and will last up to about five years. which was postulated by Melzack and based) while, on the other there are More recently we have seen the lithium Wall in 1965 and has proved to be the some relatively old fashioned instru- cell which has a life expectancy of starting point for the treatment of mentation compared with the state of ten years and finally the nuclear cell the art technology being used today. which is estimated to last 25 years but Left: this recorder provides permanent The medical profession has always been only time will tell. chart records of eight patient para- a conservative one but it will be inter- Internal devices are preferable to meters on a common time base. esting to see in the years to come how it external ones in the long term since reconciles itself with the fast changing stimulation from an external source Right: this equipment is a high speed technology and wide opportunities the requires a considerable level of current analyser for ambulatary monitoring. ,marriage with electronics can provide.

Electronic Engineering December 1976 _79 _ 50 on enquiry card Module Library

D Wire-wrappable interconnection packaging system

D Complete yet flexible — sizes standardised

ID From development to production with minimum delay and redundancy

D Meticulously designed —combines all the elements often overlooked or com- promised

O Incorporates precise module guidance, vibration suppression, correct grounding and power distribution

El Unique provisions for heat sinking, noise suppression and contact protection

ID Digital, analog and interface modules all available Standardisation leteetie uoReslpiepueis

Teradyne Components Limited, 47a Newnham Road, Cambridge CB3 9EY Tel: Cambridge (0223) 66896/7

51 on enquiry card Just connect up and read out That's the simple story extends up to 180kV. And such behind our complete and new versatility makes it ideal for à range of high stability, high whole host of activities, voltage, de voltmeters. particularly in laboratory and Compact and versatile, they quality control inspections. neatly complement our existing Just clip the coupon below 10kV to 120kV models. for our illustrated brochure and It's the only meter range that full technical specification.

mai ma MI Ina fflfflfflffll Ian Iffl riPlease send me details of the Hunting Hivolt 0-180kV dc voltmeter. Name Company Address HUNTING Ji HIVOLT LIMITED Old Shoreham Road, Shoreham-by-Sea, Sussex BN4 5FL. LTel: 07917 4511-8 Telex: 87466. NZ MR Inn ffll Iffl Inn MI MU

80 Electronic Engineering December 1976 e•-• -

83 on enquiry card

British Central D.T.V. Group Ltd Farnell Lock Distribution Spenco Electrical Ltd. 126 Hamilton Road Electronics Ltd Neville Street Electronics Briticent House West Norwood Canal Road Middleton Road (Phoenix) Ltd 172 Honeypot London SE27 Leeds LS12 2TU Oldham 79 Carron Place Lane Telephone: Telephone: Leeds Telephone: Kelvin Industrial Stanmore 01-670 6166 (0532)636311 061-652 6166 Estate Telephone: East Kilbride, 01-204 9111 Scotland Branches at:- Telephone: Slough 28616 East Kilbride Mitcham (03552)36311 01-640 9121 Cosham (07018) 83621 Yeovil 5596 Twickenham 01-894. 7561' Chingford 01-529 3715

Your nearest phone will solve your encapsulant problems. Immediately.

Whatever your encapsulant, potting or sealant requirements, your local specialist Dow Corning distributor is able to supply you immediately. Wherever you are, there is alocal Dow Corning siliconetrained electrical/ electronics product expert to help you.

DOW CORNING

f11NINt,

Electronic Engineering December 1976 81 88 on enquiry card

New micro processor controlled LRC digital meter from ESI

Tranchant bring you ESI 's latest auto LRC Meter -Model 296. It measures R, L, C, G and calculates D and Q. Because it's microprocessor controlled, the cost of optional features is reduced making them plug-in accessories. Model 296 is the perfect answer to your manual or automatic testing of components. A 24 button keyboard enables easy selection of function ranges, test voltages and frequencies, or these can be programmed via the optional IEEE 488-1975 interface bus. Here are the features that make the 296 a money-saver for anyone with QA on his mind:

dual 4/12 -digit displays. * 1kHz and 120 Hz freq. * wide ranges (C to 200,000.uF). * 0.1% basic accuracy. * autoranging. * selectable test voltages. * 100-300 ms measurement speed. * low cost options including: IEEE 488-1975 interface bus. limits comparators. higher measurement speed. D.C. resistance measurement.

Capacitance Inductance Resistance

Full 1kHz 0to 20,000.m F 0to 2000 H 20 m Ç to 2M S.2 Scale! 120 Hz 0to 200,000.0 F Oto 20,000 H 20 m fj to 2M S2 Ranges D range is 0.0001 to 1.9999. Q range is 0.5 to 10,000. Gp 200 Sto 2000 nS. Send for your copy of the 296 data sheet giving full specifications today. I. tranchant electronics (uk) limited el si 1. Tranchant House 100a High Street ELECTRO Hampton Middlesex TVV1 2ST SCIENTIFIC Tel: 01-979 0123.

71 on enquiry card High current earth continuity tester.

The Devices Bonding Tester provides an effective and convenient means of determining the resistance of earth continuity paths and will assist engineers responsible for the testing, installationand maintenance of electrical and electronic apparatus. Conventional continuity meters provide an output current of about 50µ A but the Bonding Tester applies 6V. and delivers 25A. with an 0.12 load. The short circuit current limits at 30 A. The compact and portable instrument is mains-energised with the output isolated from the mains. Flexible leads terminated in aclip and probe provide heavy duty connections to the apparatus under test and a four inch meter indicates resistance values between 0— 1St.

Mt ti'

:djustd eate teort loads Itoitiry'e A leaflet is available from

00010 10 M

t CerteedSeeleti Ottcee Ltrad earth WI 2chassie. .000 geed oMtMO with Pisa,' lOtit. ise. S Switch on tar Smere,do and reed nesietenet setae. Sieetett ou bekint ele00eiele IDevices1 Devices Limited Hyde Way, Welwyn Garden City, Hertfordshire AL7 3AP, England. Telephone: Welwyn Garden 28511. Telex: 269404. Cables: Devices Welwyn Garden Devices-experience that shows-.

82 Electronic Engineering December 1976 70 on enquiry card +. (The Meaning of Sprague Leadership; aseries)

SPRAGUE LEADERSHIP: PROVEN, BRITISH MADE TANTALUM CAPACITORS

These gelled electrolyte, sintered tantalum capacitors. To ensure that leadership. SPRAGUE LEADER- anode Tantalex® capacitors form every production-line capacitor will SHIP in service to our customers. an important part of SPRAGUE's measure up to such exacting stan- total capability in tantalums. dards, SPRAGUE-Galashiels has • All inquiries, on any aspect of initiated astringent quality control this advertisement, should be Produced to the very high- programme. Called "customer addressed to: Mike Jones, Sales est standards of quality at our oriented QAR", it offers optimum Manager, Sprague Electric (UK) Galashiels, Scotland factory, our application performance security. Limited, 159 High Street, Yiewsley tantalum capacitors are especially West Drayton, Middlesex. noteworthy for superior volume Equally important to customers Telephone W. Drayton 44627, efficiency and low leakage current. is the quality of the sales/service telex 261524. Moreover, they offer exceptionally organisation. Our's, experienced in fine performance — with respect to electronic engineering and with frequency and temperature varia- an indepth knowledge of the tions — over an extended capaci- SPRAGUE product line, provides tance range. unexcelled technical assistance.

Such characteristics, plus true Or, in circumstances calling for glass-to-metal hermetic sealing aspecially designed component, a and minimal case size, contribute SPRAGUE-Galashiels engineering to their extensive use in military specialist will work directly with the and aero-space equipment. customer to resolve the problem. SPRAGUE® Applications, like these, attest to This combination...the right THE MARK OF RELIABILITY the technological capabilities of our people —the right product...means • • ' • "

125 on enquiry card 67 on enquiry card Kenure Precision Developments Low Torque Limited Potentiometers

Also manufacturers of , 1 PCB Trimmers Electronic Simulation Equipment Digitisers Decoders Precision CearAssemblies Electronic Test Equipment Rectilinear Potentiometers

Kenure Developments Limited

Blackwater Station Estate, Blackwater, Camberley, Surrey. GUI7 9AQ 111 Telephone 0276 32111. Telex 858719 68 on enquiry card New Series 100 Extension of the fuller range of Panduit DIN Connectors

Announcing the new Heinemann Re-Cirk-It pushbutton circuit protector NEW FROM PANDUIT— Extension of the two piece Series alow-cost direct replacement 100 DIN Connector range, offering male and female connections with 32, 48, 64, or 96 contacts. for afuse and fuseholder UNIQUE TO PAN DUIT— Individual female contacts can be removed or exchanged. Polarizing key-way eliminates 180° Send for Re-Cirk-It details mis -mating. and data on solid state devices Extended bent pin printed circuit versions now available. Like to know more ?Write for full technical data. to SOLE AGENT. "'lease send technical data on Panduit Series 100 Connectoril Electro-Match Limited "Name Position 57 Ashleigh Road ICompany HORSHAM 'Address Sussex RH12 2LE Phone:(0403) 68756 Panduit Limited, Sittingboume Industrial Park, Unit 22e. Crown Quay Lane, Sittingboume, Kent. Te/ex:877361 Fintyre Bhurst Telephone: (0795) 75333 Telex 965393

84 Electronic Engineering December 1976 72 on enquiry card There's a lot to be said for having good connections in the right circuits. Connectors specially for printed circuit boards Also for lOmm phi with 5mm pin spacing. spacing in both 6 amp Suitable for up to 10 and 10 amp ratings and amps, 660 volts in 2 to 2-12 ways. 24 ways. -

All types are available with cable entry at the top Single push-on tab type reeem instead of at the connectors for 5mm spacing are side, and are recommended for individual moulded in grey, connections. Current ratings 6, 10 glass reinforced and 16 amps at 250 volt ac. for nylon 6for 1 2.8mni, 4.8rnm and 6.3mm size temperatures up to receptacles. 110 C.

The 6 amp, 5mm Wire protectors can-",.. pin spacing be fitted to all connectors are patterns to give made for 2, 3, 4, 5, 6 added protection to \C": and 12 way cable strands. connections.

Our range also includes push-on edge and miniature plug-socket connectors and fuse-holders for PCB's. For full details send now for our catalogue 1VIE1 73ISEC 3 Metway Electrical Induatries Ltd., Canning Street, Brighton, BN2 2ES. Tel t0273 66433/4/5.

VERDURE: GET THE CONNECTinduíd

• A new and ideal wiring system for proto- types. Breadboards, and limited production. •Achieves a permanent interconnection of components, at high speed, on avery high density. •Based on the use of Verowire(R) wiring pen with unique spring wire clamp for wire retention, advancement and retraction. •Moulded wiring combs fitted to board route the wire from point to point neatly holding and stabilising the wiring layout •By using aspecially designed tool, I.C. legs are deformed and positively held in the board enabling the wire to be easily wrapped around them. • Using a self-fluxing polyurethane coated wire, no pre-stripping is required. Connec- tions are completed by soldering, melting the insulation and at the same time making apermanent soldered joint. •A complete introductory Verowire kit is available consisting of a wiring pen, spools of wire, terminal pins and all tools necessary. You only require a temperature controlled soldering iron to Verowire a board. A sample board from the Vero high density D.I.P. board range is also included in the introductory kit.

Vero Electronics Ltd. Industrial Estate, Chandler's Ford, Eastleigh, Hampshire SO5 3ZR. Telephone: Chandler's Ford 2956 Telex: 47551 Available through 3subsidiary WORLD LERDER5 In POMPOM TELHROLOGY Companies and 25 agents

Electronic Engineering December 1976 85 -"----71.771 117,11777"7.errl!

74 on enquiry card 75 on enquiry card Filtered!

WE REIGN SUPREME

AS STOCKISTS OF: Having trouble with mains-borne voltage transients? Our combined three pole mains connector/interference filter unit solves the ELECTRICAL problem! Interested? CONNECTORS Bypass Rd. Barking Essex Distributors for: BULGIN Telephone 01. 594 5588 Plessey Interconnect Ltd Thorn Electrical Components Ltd 76 on enquiry card Flight Connector Corp (USA)

Stocks also held ofelectrical connectors from: Amphenol Ltd Belling & Lee Ltd Greenpar Engineering Ltd ITT Cannon Electric (GB) Ltd Precision Electronic Terminations (EMI) Ltd Post Office Specials Services/ NATO Specials

LAmps AND LIGHTING . EQUIPMENT Distributors for: * Cryselco Ltd In certain situations, there's every need to get alarmed. And Osram (G.E.C.) Ltd we've the means of creating a song and dance about virtually Rival Lamps Ltd any situation. A series of miniature, solid-state electronic audible alarms Thorn Electrical Components Ltd capable of operating from a whole range of d.c. supplies: 1.5V; Grimes Manufacturing (USA) 3V; 6V; 12V; 16V — and now 24V too. Leecraft international Corp (USA) They're simple to install, most economical to run, and built to endure. And we can provide them with either acontinuous or intermittent tone. Stocks also held of lamps and lighting So don't wait 'til it's already happened. Call us right awày. equipment from: It could be a sound investment. Hivac Ltd Vitality Ltd

AVIATiON ELECTRICAL & RADIO Co. Ltd. Roxburgh. Way out front. Roxburgh Electronics Ltd, Moons Lane, Horsham, West Sussex R H13 5BY 22 Winchelsea Road, Rye, Sussex. 1el: Horsham 60206/7/8 (STD code 0403) Telex: 87645 Telephone: Rye 3777, Telex: 957066. 2522

86 Electronic Engineering December 1976 124 on enquiry card Professional rectangulars from Plessey are high on quality yet low on price

Quantity production using the most advanced, automated assembly and test procedures enables us to offer professional quality, general purpose rectangular connectors at lowest possible cost to you. The current ranges of Plessey multi-way connectors incorporate many valuable features — the result of many years' specialised experience in the development of electronic connectors. And available from stock Multicons and 159 series rectangulars are in full production and available for immediate delivery from your usual Plessey distributor.

PLESSEY (0 CONNECTORS F.C. Lane ITT Farnell Plessey Horsham Electronic Services Leeds (0403) 790661 Harlow (0532) 636311 Distributors (0279) 26777 Ilford Sasco AERCO (01) 478 3040 Crawley Intel Horsham Ext. 3391 (0293) 28700 Henlow (0462) 812505 (0403) 60206

Electronic Engineering December 1976 87 A - 7.— •

77 on enquiry card uro rges connector manufacturer

for quality connectors, switches, heat dissipators & bus bars SOURIALI Souriau connectors and components are used throughout Europe in applications ranging from computers to oil rigs, telephone exchanges to Concorde and metro systems to MRCA. Our standard product ranges cater for every type of industrial and aerospace application. If you'd like our latest product information, circle our reader reply number or telephone us at 075-35-69471. SOURIALI (UK) LTD. ;Shirley Avenue, Windsor, Berkshire. Telephone: 075-35-69471 Telex: 848456

*a.

88 Electronic Engineering December 1976 PRODUCT FOCUS

This market analysis is con- land and 7% in the West Mid- cerned with manufacturers and lands. Although for the com- distributors of "professional" ponents market, these figures connectors, that is types of more or less match the pattern connectors normally used in the for the connector breakdown, field of military equipment, except that an estimated 60% is aerospace, telecommunications, concentrated in the South East. computers, instrumentation and Over the past five years the underwater. The newest de- average growth of the industry velopments in the connector (connector) appears to have field relate to the requirements of been approximately 18% per under water exploration, where annum, but this is based on sales depths of working are becoming figures and seems to convey a such that, the so-called "sealed" completely false impression. The connector is rendered un- very large increases in material suitable; the growth of fibre- and labour costs in the period optics and the increasing use of '73-'74 undoubtedly resulted in flat cables both with standard increased selling prices distort- and flat-foil conductors. ing the figures to such an extent When assessing UK market that the real average increase is shares companies become un- nearer 6 to 7%. In 1975 price willing to release specific sales increases by major companies figures, or where they manufac- varied between 10 and 30%, the ture a number of different types average figure being 18,5% of component figures relating which is considerably more than specifically to the professional the growth figure for 1975 over electronic connector sales and the previous twelve months. therefore the figures obtained are CON \ECTORS There are currently more than assumptions made against the 40 manufacturing companies yardstick of those companies. engaged wholly or partly in the Ignoring the effects of business recessions, which Total market estimations arrived production of professional con- tend only to slow the development process, it is at, have given a figure of £46 nectors, anumber of them multi- reasonable to assume that the overall trend in million which includes the export million pound concerns with connector development will continue and in the sales of British made items. This diverse interests. Of these com- not too distant future there will exist a demand figure is substantially more than panies seventeen now appear to for emore advanced design of environmental any official statistics as com- have connector sales in excess of connector, superceding existing designs for specific panies who did not make a £1 million per annum and with applications—writes Brian Jennings. return are included. The follow- total sales of over £38 million, ing breakdown for connectors this means some 47% of com- gives the percentage share of the Table 1: Connector classifications panies share 85% of the esti- UK produced component sales mated sales. (including export) and an esti- Home product Total sales mated total sales including im- Description sales £38,22m £45,90m End of recession ports. The market is roughly Whilst there are signs that the divided into the five classifica- Multiway circular 28,63% 29,33% recession is coming to an end, an tions. See Table 1. Printed circuit types 33,05% 31,59% upturn in the industry is not To list all the companies, their Rectangular (rack Et panel) 17,21% 17,77% foreseen until mid 1977 and only types of connector and billings Co-axial 10,34% 10,75% in the region of 10% of the 1976 would be laborious and beyond Miscellaneous 10,75% 10,53% figures. This is, of course, assum- the scope of this aspect of the ing that prices remain at their article. Therefore, the following present level and that there are compilation of twenty six com- Table 2: Company market shares no further cuts in Defence panies with sales exceeding spending, since although this £250 000 represents ajustifiable Market Market primarily affects one sector of the insight into the connector mar- Company Name Share Share connector market it is the sector ket. The listings conform from containii.6 the highest value the greatest to the least market Cannon 9,87 Varelco 3,04 units and consequently has the percentage. See Table 2. Plessey Interconnect 9,43 Smiths Hypertac 2,78 largest impact on overall figures. The remaining 3,74% is Amphenol 8,69 Sealectro 2,60 For a designated period, to claimed by a further fourteen UECL 6,26 Belling-Lee 2,19 the end of 1980 the average yearly manufacturers. BICC Burndy 5,58 Souriau 2,06 increases, based on •current The figures quoted in the pre- Hellermann Deutsch 5,32 Precision Elect. Term. 1,69 prices, will grow at 8,5% per vious paragraphs do not include Thorn Electrical 5,19 Ferranti 1,65 annum, although yearly fluctua- dual in-line sockets, of which Carr Fastener 5,04 Hughes Micro tions are inevitable. both imported and UK manu- electronics 1,36 Technological developments factured versions account for an AMP of Great Britain 4,73 Transradio 1,07 during the past few decades estimated £1 million per annum. Pye Connectors 3,93 Suhner 0,86 have significantly advanced the Statistics published in 1974 Greenpar 3,47 Viking 0,86 performance capability of elec- (the latest available) show that A.B. Electronics 3,47 Henry Er Thomas 0,86 trical connectors where there is a 45% of the components industry McMurdo Insts. 3,26 M ullard 0,76 continuing need to improve is concentrated in South East designs to meet requirements England; 11% in the North particularly for performance, West; followed by 8% in Scot- Fig 1. Typical selection of pc cable connectors from AMP size, weight and reliability.

Electronic Engineering December 1976 89 -%7•7 ' 1 ç:XIt5l!legelLee,

78 on enquiry card 79 on enquiry card A sweet little number by Honeywell Double

That's what you experience with the Vision Comparascope . . .simply a better method of checking P.C. boards, or any other products that must be visually identical. The Comparascope is several times faster than conventional viewing methods, yet offers greatly improved reliability, showing up any difference between two objects immediately.

For further information on the Vision Compara - scope, or to arrange for a demonstration, please telephone or fill in the coupon and send it to us.

Design Council Award 1974

( design award 1969

You get quite alot in a lib bag — about 75 — and they'll all be different. In fact there are so many different features you can specify that you could buy acwt and still have them all different. With all that range of different miniature switches to choose from, there , Ezsgisseextiamg Ltd. must be one that suits your need. SEND ROAD, SEND, WOKING, SURREY GU23 7ER, ENGLAND just try one -you'll be Tel: Guildford 223417 Cables: 'Vision' Wo king Telex: 859301 To: Vision Engineering Limited sure to come back for more Send Road, Send, Woking, Surrey GU23 7ER England Please send more information on the Vision Comparascope Please ring me to arrange a time for a demonstratioi, (Tick as appropriate) Name Honeywell Posit ion Organisation Address

Honeywell Ltd. Honeywell House, Charles Square, Bracknell, Berkshire. Tel' RG12 1E13 Tel:0344-24555 or your nearest Authorised Distributor EE12

90 Electronic Engineering December 1976 PRODUCT FOCUS

The extent of this development conventional size shell and to can best be assessed by com- progress beyond this figure paring performance characteris- would necessitate the introduc- tics of modern day designs with tion of an entirely newconcept. those available fifteen years ago. On the applications front a Working temperatures have multiplicity of connector re- doubled, contact density has quirements abound. Take for increased by a factor of five, instance the "low-profile" con- weight per termination has been nector, here the requirement is reduced by in excess of 80% and for the overall height of the the rate of connector failure for connector relative to the mount- present designs is better than ing plane to be as low as possible. 0,05/106 operating hours, com- They are mainly used in positions pared with 1,5 for older designs where there are space limitations operating in less severe areas. and restricted access for coupl- This particular assessment ating/uncoupling, or where con- tempts to look at developments nectors are unprotected in situa- during the past years, to examine tions where they are vulnerable factors that have influenced to damage. The profile dimen- connector designs and to define sions of a connector design are parameters that are likely to form dependent upon the length of the basis for the next generation. the termination systems including the wire sealing and support Life -span patterns mechanisms. The trend is cer- Assessing established con- tainly towards shorter length nector designs reveals that the contacts and a reduction in wire life span for most environmental sealing and support mecha- (multi-way) connectors follows nisms. The extent of problems apattern that is common to most relating to maintaining com- designs, catagorised in three patibility with developments in identifiable stages. Firstly, initial wire design can be appreciated development against a specific by the following comparison. In requirement, here environmental the early 1950's the overall connectors are designed to meet outside diameter (0/D) of a the most severe user require- wire used in aerospace applica- ments at the design concept tions was 2,5 mm with the stage. These are predominantly conductor accounting for 1,2 aerospace applications. mm. Today the insulation O/D Secondly, the establishment of Fig 2. Sectional view of contact retention from Amphenol is in the region of 0,6 mm with acomplete range of connectors, the conductor diameter some during this stage of development 0,3 mm. This basic example at the availability of connector tamed in various national specifi- geneous range of connectors least illustrates how conductor styles increases steadily as a cations introduced since 1950 and predict that future specifica- and insulation diameters have design gains national and sub- provide an interesting study of tions will contain between 30 decreased since the introduc- sequently international recog- trends in performance require- and 35 individual performance tion of crimp terminations. There nition and becomes available ments. To obtain design approval requirements. Consistent with is little doubt that future wire from anumber of manufacturers. for arange of connectors in 1950 this conclusion, it is reasonable developments are going to pre- Thirdly, the replacement by im- it was necessary to meet the to assume that there is apractical sent design problems for con- proved design, here the gap requirements of 11 individual limit to the amount of per- nector designers and as pre- between user requirements and performance tests, today the formance testing which can be viously mentioned, entirely new the performance capability of a average number of tests per applied to aconnector, and that designs are foreseeable for wire connector design increases and design is 31 requiring in many we have reached this stage. This sealing and support mechanisms. as improved designs become instances a much higher level of being the case, then new tests available there commences a performance. During the same which will inevitably be intro- Weight critical stage where the design is no period the number of individual duced in the future can be The problem of weight is longer acceptable. tests introduced for the purpose expected to replace, rather than critically important in aerospace Present day specifications of measuring the performance of supplement existing tests. applications, where large quanti- covering environmental con- environmental connectors in- During the past decade or so, ties of terminations are used; an nectors are essentially adaptions creased from 12 to 58, this there has been a distinct trend example being, that the most of proven techniques, capable of would seem to be an indication towards a greater usage of low advanced connector design in suiting new or more severe user that many tests are introduced power circuits and connectors use today proffers a weight per requirements and because de- covering specific requirements with high contact density inserts. contact some 20% of the figure signs and specifications tend to for particular designs having no Responding to this demand for of earlier designs. As a point of evolve as a simultaneous pro- practical value as standard tests. higher density termination sys- interest a "Jumbo Jet" can cess, in many respects they To establish a more realistic tems acorresponding change in contain as many as 6000 con- represent the limitations of cur- trend in performance require- connector designs has come nectors representing approxi- rent technology. Even so, per- ments it is necessary to eliminate about. Within the limitations of mately 150 000 connections and formance specifications provide the effect of generic specifica- maintaining conformity with 200 km of wire! essential design criteria enabling tions covering more than one existing designs, the present For both simple and compkx the designer to accurately define basic design. After making ad- high density connectors are designs a connector can only minimum acceptable levels. justments of this nature, it is close to the practical limits of fail if the conductors or the An analysis of the quality possible to indicate a general present technology. This limit is dielectric supporting the con- assurance requirements con- trend applying to an homo- placed at 200 contacts in a ductors cause an unacceptable

Electronic Engineering December 1976 91

•••••••0 ..E.1.•«•••M•••••• Multi- Radiatron ne otlts ct way Comz:Produ ELECTRONIC COMPONENTS 2 Piece PCB Connectors Connectors The series 219 is designed for 8-141-Los.: rack and panel systems where a Today's reminder of what you can get from high contact density is required. II • 2 or 3 row — up to 96 Radiatron Components right now contacts • Contact pitch 2.54mm professional choice for connectors. • Qualified to V.G. 95324 • Wire terminations for solder or wrapping Our Erni range of direct and • Housing and contact polarization indirect Connectors has all the approvals to win your approval, mrmirrrnwl with exceptional performance 160 on enquiry card under severe shock and vibration conditions. Wire Wrapping Equipment A complete range of wire STV 2M and 3M wrapping tools and accessories 96, 64 and 32 way, two part from Standard Pneumatic. • Standard bits and sleeves for PCB connectors designed to wire range 18-32 AWG, with DIN 41612. facility for standard and Three Families. modified wrapping • Manual, pneumatic, battery (a) Military spec. VG 95324. and electric tools (b) IEC standard. (c) Industrial standard. NEW•Range — 'CSW' 20-30 Bits AWG. and Sleeves. A very wide range of termina- • Cuts wire — strips and wraps tions is offered. all in one operation to Circle Reply No, 164 produce the lowest applied al connection cost. A special 160 way version is STV 311 161 on enquiry card designed for computer applica- High current capacity two part tions. PCB connectors 20A ,32 ways. Electronic Test Circle Reply No.165 Equipment Accessories A comprehensive range of components including STV D • Adaptors for BNC receptacles Direct PCB connectors Euro- and plugs to banana plugs card and 19" standard versions. • Binding posts • Shielded boxes with externally Circle Reply No.166 mounted coaxial connectors • Cable assemblies with stress relieved BNC connectors, TMC banana plugs, UHF Two part trapezoidal chassis connectors, clips and test mounted multi-way connectors. probes Circle Reply No.167 • Patch cords • High voltage probes up to 36KV Connector housings 162 on enquiry card • IC test clips Available as required. Circle Reply No1168 Wire to Board Connectors The series 237 is a modular connector manufactured in two, three and six way modules which assemble to each other, per mitt ing rFor full details of any of these Radiatron Products, complete anc71 combinations of two or more return this coupon or circle the appropriate reply number. ways to the maximum desired number. NAME • 5mm pin spacing • Screw clamp with wire POSITION protector • 380V.16A COMPANY • Additional end fixing pieces for screw fastening ADDRESS 163 on enquiry card • 2mm test socket facility M Radiatron HELLERmAnn \ Components Ltd T Gus ad ELEcTRonic ;eti:,;E(.E4,R,?.::i211e231Telex: 85118 27411 Crown Road, Twickenham, Middlesex, TWI SET Cables:CONNECTORS L ST : Telephone 01-891 1221 Telex 267807 EAST GRINSTEAD EE12/76 comronEnT Helleemann ltd.

92 Electronic Engineering December 1976 °""dierferallreffle"7-':=7—• - .

PRODUCT FOCUS

change in the electrical charac- would put the manufacture of of performance for high density addition to establishing apattern teristics of the circuits being con- contacts in the watchmaker designs comparable with, or of development for multiway nected. Maintaining a satisfac- classification but only a small better than designs utilizing connectors, the previous para- tory level of performance for reduction in size is possible larger shells and contacts. graphs only substantiate that circuits that are becoming more before costs become a pro- Like everything that offers a little has changed in the past few sensitive to conductivity varia- hibitive factor. benefit, there are trade-offs, the decades. Suggestions have been tions, in environments that are The introduction of new plas- most noticeable in this instance put forward that future develop- becoming more hazardous, is tics materials has probably con- is the cost for performance. ments will either recognise this today's connector design prob- tributed to the greatest advance Sophisticated designs have a fact, in which case new designs lem. This situation is accen- in connector design in recent rate increase three times greater will utilize round shells, crimp tuated by the reduced size of years. Rear removable designs than for low performance pro- terminations and wire sealing, or contacts and dielectric wall are currently considered to be the ducts. These increases are readily follow a pattern rejecting con- thickness between contacts. most advanced retention sys- attributed to the effect of invention. This could evoke an During the past decade there tems in use today and are likely creased labour and materials entirely new design approach have been important develop- to form the basis for future cost. The rising cost of gold is an evolving new shapes, new forms ments in materials, both for developments. The advantages example of materials increase. of construction, sealing and contacts and dielectrics which of this form of dielectric reten- termination. It is possible that have, in themselves, significantly tion against the equivalent metal- Five fold increase future developments in this field advanced the technology con- clip design, see Fig. 2, are The trend during the period will employ the use of technolo- cerning connector manufacture. shown in a better and more 1970-75 shows a five fold in- gies such as conductive elasto- Contacts used in high density reliable performance characteris- crease in cost for plating 2,5 mers or field serviceable elec- connectors have an inherent tic of the dielectric, which offers microns of gold. Despite major tronic welded terminations. mechanical weakness due to an improved electrical and tem- activity in the search for a less Irrespective of the form of their small diameters. This has perature endurance property. costly plating finish, manufac- interconnection, one aspect is created a need for high con- The stability of dielectric mate- turers, particularly those in high- paramount in a manufacturers ductivity alloys with properties rials under thermal load can be grade types, will continue to use mind, quality at a competitive providing a combination of related to the degree of out- gold plated contacts. Future price. If a producer can insert mechanical strength and ductility gassing which occurs, assessed developments in this field are a component into an assembly for crimping in one piece. by measuring the amount of expected to concentrate on im- and anticipate zero defects on With currently available mate- weight loss. With the advent of proved performance from thinner the product, he does not en- rials there is scope for a further improved materials and designs deposits of gold and the use of counter rejects and the subse- reduction in size. This in itself it is possible to maintain a level selective plating techniques. In quent overcost operation.

80 on enquiry card

NEW LEMO 'B' RANGE

Made to the same standard of mechanical perfection and aesthetic beauty as established LEMO connectors and incorporating the well- known LEMO self-latching system but with the following new features.

1. Integrally machined keying system to prevent misnnating and/or insert damage. 2. All internal components keyed to each other and shells to prevent rotation. 3. Crimp/solder contacts in RYTON inserts. 4. Increased contact density. 5. Easier method of assembly. 6. Self-locking collet system. LEND LEMO (UK) LIMITED

WORTHING HOUSE • 6 SOUTH STREET • WORTHING WEST SUSSEX BN11 3AE TELEPHONE: WORTHING 204651 TELEX: 877543

Electronic Engineering December 1976 93 rom ASTRALUX Ltsocke NEW EXTRA LOW PROFILE I.C. SOCKET I.C.L. SERIES • Low profile of 0.150" allows closer ▪ Gold or tin plated contacts to suit pitching of P.C. boards. customer's requirements. • Designed to be mounted end-to-end ▪ Reduced assembly costs due to and side-by-side on 0.100" matrix. automatic assembly feature. II "Self-locking' leads retain socket in III From 8to 40 ways, giving versatility the printed circuit board during wave from one manufacturer. soldering. III Easy I.C. insertion with high I.C. Famous R-N 'side-wipe' retention force under vibration sockets for better contact conditions, by unique contact design. All this plus the famous R-N side wipe ▪ Wide temperature range (-65°C to + contact design, which makes contact with -I- 125°C) by the use of flame resistant the wide smooth side of your I.C. leads. glass-filled polyester. Contact integrity starts better, stays dependably trouble free.

Production I.C. sockets, test sockets, plugs, headers, socket boards— a total I.C. capability byRobinso n Nugent. Renovvned vvorldwide for Quality, value and advanced features. 411 UK available, fast from Astralux Dynamics, backed by Astralux ines know-how and services. 1)ring you the Top l in stock here—and every tire 1101)111e"» Quality production I.C. sockets up to 64 way! Col• ske I.C.N. SERIE sreek Suitable for up to 80 insertions/ withdrawals, ideal for prototype work. Solder tail or wire wrap deist* terminations cater for most design needs. Gold or tin plated contacts. Designed for automated I.C. insertion by means of special frame design. le h1 Available in various or for hybrid circuits. configurations from 6to 64 ways. Pitch as plug and socket Suitable for your burn-in ig Available in any size up to 25 ways on 0.100' applications, with special high temperature version Solder tail termination (SB series), or wire (-65 °C to + 220°C). wrap terminations (VVB series).

II High temperature option (-65°C to -I- 220°C)on SB series caters for burn-in needs. Alow-cost option too. I/1 Goldplated contacts. It Special nny-Strip, at, Low cost option—ICY series, same range and design features but with tin plated copper alloy contacts for vvide to suit 0.100"contact spacing on economy. 0477/both X and Y axis (SS-100 series). 0.100» comPAnacE 114Are other R-N product flown in to order, HEADE so smartly you'd hardly notice the difference !Make sure acatalogue 111 Available in any size up to 25 ways. and selector guide is on your desk 170141. Right angled solder terminations. (VVB—PR series) for flow solder app. lications. Astralux Dynamics Limited, e SerStraight-throughies) pin termination (t4/8—P Red Barn Road, Brightlingsea, Colchester CO7 OSW. Telephone :Brightlingsea (0206-30) 2571/5. plated contacts. Telex: 987751. AN ANTIFERENCE GROUP COMPANY lugent rangewread all a 011 of 82 on enquiry card

The Swedish Connection At its best in every way in the LM Ericsson range of X-connectors Design ere Quality Reliability ek Price

The new 20, 40, 60 and 80 multi-way connectors in the unique, snap-close plastic casing. The standard range in 20 to 600 ways. The special designs of multi-way connectors up to 1,400 ways. AIL COMPONENTS LTD. Aberdeen Avenue, Slough Trading Estate, Slough, Berkshire Telephone: Slough 20961 Ext. 44

Sole U.K. Agents for the components of LM Ericsson of Sweden

96 Electronic Engineering December 1976 0.^.14.,111e

PRODUCT FOCUS

The trend today is toward total credence, since the reduction in mm pitch, except for specials assembled cost applied to the inventory makes for amore com- because of the handling limita- product used, rather than just the patible interchange. The Molex tions. On the plating front, a purchase price of the component. miniature (KK) interconnection greater degree of tin and tin lead More and more consumer pro- system for instance rationalises will be used, especially where ducts are utilizing ic's as the cost the use of plastics and metals, terminal design can insure agas of the device goes down and providing the user with an eco- tight contact interface. reliability in performance in- nomical, yet comprehensive The benefits to be gained from creases. The introduction of board interconnection system. A ribbon cable assemblies are these devices causes problems at variety of connectors have been manifest, for instance, speed in engineer level, with servicing designed permitting vertical and digital equipment has reached costs and warranty periods in- horizontal harness-to-board and the point where shielding and creasing, an early decision must board-to-board linkages. These attenuation have become critical. be made into the form of offer the facility for plugging The use of co-axial cable in connection; ie, sockets for ic's daughter boards into their re- volume applications was un- or direct fastening to the printed spective mother board, from economical but now, with the circuit board. The decision to use either side. introduction of co-axial ribbon sockets is usually made because As stated previously, modern cable assemblies the problems of the sometimes questionable day trends are towards less associated with the economics reliability of the ic's and, because material usage and greater flexi- and reliability have been drama- the manufacturing techniques bility, furthering this philosophy tically reduced. The AMP system used in assembly do not normally toward greater standardisation as an example, includes 50 ohm produce the close centre spac- and interchangeability. With the Ribbon cable connector design cable and 20 co-axial conductor ings required for available dual- continuing development of ic's connectors mating with 0,64 in-plastics. A plug-in, removable there will be a greater usage of seen, both for discrete, ribbon mm 2 posts. They are applicable capability is todays requirements low or zero insertion force and flat cable as well as for to 90 degree board mounted pin for fragile or failure potential devices. More reliable inter- connectors and sockets to pcb's. headers or I/O posts on 2,54 mm components, so too is this capa- connections for flat and ribbon Connectors with foolproof mat- grid spacings. The ribbon cable bility desired for assembly of cable will appear especially in ing will proliferate and, similarly, consists of 20 individual co- modular designed units. The the one operation termination connectors will reject themselves axial cables encased in a pvc idea of a systems approach to approach. A greater capability in if not fully mated. Sizes will jacket, making up astandard flat interconnection is fast gaining automated attachment will be almost certainly remain on 2,54 co-axial ribbon cable configura -

83 on enquiry card Entrelec component terminals from HIGHLAND ELECTRONICS Polarised Plug & Socket for diodes, resistors, fuses. Nap fit fuse carriers to 33A 10A screw in type fused terminals disconnect switches. Range of P.C.B. terminals 0.2" pitch.

ex-stock deliveries from Scottish Factory Highland Electronics Ltd Donibristle Industrial Estate, Dunfermline KY11 5J Fife, Scotland. Tel: Edinburgh (031) 331 2506. Telex: 72672. and from our Scottish distributor W.S. McMillan & Co. Ltd. 61, Colvilles Place, Kelvin Industrial Area East Kilbride (03552) 38641. Telex 778771. Highland Electronics Ltd 33-41 DALLINGTON STREET, LONDON EC1V OBD Tel: 01-253 9107 Telex: 267284 Cables: Hielec London E.C.1.

Electronic Engineering December 1976 97 84 on enquiry card

Introducing EDGEBLOCK BJ the combined EDGE connector and screw terminal BLOCK.

Pye EDGEBLOCK BJ is unique. A he quality PCB instrument, plug your printed circuit board directly edge connector and screw terminal block combined. into EDGEBLOCK BJ. Externally, make your screw In arange of sizes 4to 24 way on 0.2" centres, terminal connections in the usual way. The saving's single-sided. enormous. Materials, stockholding, time, expense. If you manufacture electronic instruments you No intermediate wiring, soldering, wire wrapping, don't need PCB connectors andscrew terminations power tools. And fewer wired connections just has anymore. Just use EDGEBLOCK BJ. Inside the to improve the quality of your product. All with greater packaging density. Servicing's simpler too, if you ever need it! Send for the literature on EDGEBLOCK BJ. There are many more features — all to help you save.

Pye Connectors Ltd PlItchin Suent. Biggleswade.Bedfordshae, SG18 8BH. England Tel: Biggleswade (0767) 312086 tq'P Telex :82288 PYECONNS BVVADE A 'veneer ol the Ave ol Canarege GA,AA

t "' • 85 on enquiry card

PRODUCT FOCUS 1

tion. Each co-axial lead has a insulated wire. All cables and solid centre conductor and a wire connections are preformed foil-drain wire shield. This con- simultaneously without the need struction allows the cable to be for pre-stripping the insulation cut in any length, maintaining The generation of electronics the exact positioning of the in the 1970's will create the re- centre conductor and drain wire. quirements for the connector of By using manufacturers stripping the future. Frequencies in the and termination equipment, the gigahertz range and pulse rise 20 conductor cable is stripped times in the pico -seconds re- simultaneously and then gang quire impedance matching from terminated. The signal conduc- source to load on microstrip, tors are terminated on one side of strip-line, multi-layer, co-axial or the connector and the drain cable—and sometimes several at wires to the other. Complete once. Solid-state, hybrid or Isi assemblies are presently avail- has reduced the component's able using 50 ohm co-axial rib- size to the point where the bon cable, in 20 wide configura- connector often determines the tions on 2,54 mm centre lines in package size rather than what is lengths ranging from 152,4 to inside. Many sub-assemblies are 3048 mm. As the technology of not made pluggable even when co-axial ribbon cable advances a their reliability or cost warrants wider range of connector con- it, because of the lack of an figurations will become available appropriate connector. offering a capability of terminat- If the electronic and mecha- ing 75 and 93 ohm cable. nical engineers of an advanced A further development lies in system manufacturer were to sit a magnet wire interconnect sys- down together and dream up the tem bringing insulation displace- specifications to an ideal con-

Fig 4. A selection of Radiation pc connectors

ment technology to magnet- nector for the future, it would wire termination. This insulation probably read as follows. Most displacement heralded the in- important would be the im- No holdups! We can deliver many of these precision dustries first mass termination pedance match with a vswr of application. By utilizing the same 1,0 in the gigahertz range. Jaeger multiway connectors straight from stock. Stan- concept, but in reverse, that is, They'd specify a connector so dard, quick-release, sealed and miniature types—all at by driving the terminal over a small in all dimensions that it really competitive prices. The famous Jaeger ranges are prepositioned wire instead of was smaller than the package of driving the wire into aterminal, a components. They'd want to available world-wide, to meet international specifications. terminating system can be intermix the dc and rf lines to For your needs, contact the sole U.K. distributors, achieved that automates magnet reduce printed circuit lengths Wingrove and Rogers. We also manufacture the Polar wire interconnections and is and cross-overs and want it to compatible with present day push-on with a low insertion range of Variable Capacitors, Terminal Strips and Stand- automatic assembly equipment. force. The circuit isolation re- off Insulators. Another type of connector pro- quirement would vary but cross- viding instant multiple termina- talks below 80 dB could be tions is the Latch connector. This needed. Some would specify 75 Wingrove & Rogers Ltd. device terminates flat cable with and some would need 50 ohm round conductors, flat ribbon systems. The manufacturing en- Donnville Road, Liverpool L13 4AT, England. cable, woven ribbon cable and gineer would specify easy com- Tel: 051-220 4641 conventional stranded or solid patibility with the type of trans- Telegrams: Components Liverpool 13. Telex: Chamcom Liverpool 627110 for Winrog.

Electronic Engineering December 1976 99 86_on enquiry card

BUNKER Am RAMO AMPHENOL

a" CelAlee

THE WHAT WHERE WHO BOOK FREE FROM AMPHENOL

Every Engineer's opportunity to aquire the latest facts on the extensive range of Amphenol connectors and electronic devices — in one clear short-form publication. WHAT — . , Power, Printed Circuit, Rack and Panel, Micro-Miniature, Audio, Filter- ing, Industrial and R.F. Connectors; Integrated Circuit Components; Trimming and Precision Potentiometers; Concentric and Digital Micro- dials; Relays and Keys; and Fixed and Variable Inductors. All products linked to DEF, MIL, DIN and other specifications as applicable. WHERE — A comprehensive catalogue listing of the Company's full range of literature, literally dozens of colour productions clearly dealing with each series. All publications are cross-referenced to whatever product you are interested in. WHO — The Amphenol distribution network covers all parts of the United King- dom. The organisation is thoroughly tried and tested,each Distributor has close links with the factory and trained Specialists supported by indepth stocks of 'preferred ranges' of components. This publication details specific ranges stocked by the Distributor in your region.

ALL THE FACTS IN ONE CONCISE PUBLICATION - YOURS BY REQUEST

BUNKUM RAMO AMPHENOL Thanet Way, Whitstable, Kent. CT5 3JF Tel: Whit. (0227) 264411 (12 lines). Telex: 96157

14 4 in -ir"

100 Electronic Engineering December 1976 r

PRODUCT FOCUS

mission line used and rapid There are two main methods of lead, bright tin-lead, bronze, provisional BPO approval to termination using conventional designing plug-in contacts to copper and gold over nickel, on specification D2552. The EWD methods. The reliability engineer achieve efficient mating with identically plated printed wiring series of edge connector features would have a few words on its leads on ic's. The majority of boards along with their asso- rolling leaf spring contacts limit- quality and the purchasing agent sockets and board systems are ciated card-edge connectors in ing stress. 450 would like the connector to be designed with contacts that bear an attempt to resolve a suitable free. on the shear edges of the lead in low cost replacement for gold FC Lane produce circular, alu- The culmination of this hypo- either a circular or a rectangular over nickel plating in card-edge minium or brass compatible to thesis is the Chevron-shaped configuration. The alternative connectors. The conclusions Mk4 types, pc-types, rectangu- connector, designed for the approach is acontact that bears reached so far indicate that lar, miniature and rf co-axial modern breed of fast, miniature on the wide side of the lead bright tin-lead plating is com- devices. Contact pitches for the electronic equipments requiring frame. The prime methods used parable to gold over nickel in all pc-types span 2,54 to 5,08 mm impedance matching and con- are: edge-bearing contacts; respects except durability. and the frequency limitations on nectors that will not detract from side-wipe contacts; cylindrical the rf products range from 200 Acknowledgement is afforded performance. This type of con- contacts; zero and low insertion; MHz to 12 GHz. 451 to Jordan Dataquest for the nector combines the leading force contacts. The majority of assistance given in formulating Amphenol's contribution to the attributes of both co-axial and socket manufacturers have opted market share figures. connector market is enormous, pcb connectors: intermixing dc for the edge bearing version to offering circular, high density, and rf lines in asingle connector achieve lower cost, and this Ferranti manufacture a wide power emi/rfi filtering, herme- and affording compatability with design allows these sockets to be range of edge, multi-pole low tically sealed miniature/sub- pcb's. VSWR's as low as 1,06 at made narrower, typically 10,30 force micro-circuit and special miniature, pc-types, rectangular, 5 GHz, crosstalk as low as mm wide on a 14-pin socket. connectors to high commercial rf and co-axial. One product —80 dB and signal centrelines The contact, however, bears on and military specifications. The causing interest is the Merlin down to 1,27 mm are possible. the rough, shear edges of the EZD range, available either as series of rear release, polymer Turning full circle, we arrive at lead frame, which have poor single or double sided has from contact retention clip circular finishes. As with multi-way con- sockets for ic interconnections, five to 90 ways, satisfies the connectors. This product is often defined as a source of nectors, gold plating of contacts requirement for a2,54 mm pitch commented upon and refe- trouble joining two other sources still offers the best results. component compatible with renced in Fig 2. 452 of trouble; but part of the prob- However, due to the high cost of modern racking techniques such lem is that insufficient attention the material other "substitute" as CAMAC used by atomic Qikstack is the latest addition to has been paid to the evaluation finishes are being assessed. For energy authorities throughout the BICC-Burndy range of and selection of these sockets. example acid-tin, bright-tin, tin- Europe. The EXT 100 series has GTH connectors, enabling inter-

87 on enquiry card 88 on enquiry card

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SEVERAL THOUSAND LITRE/HOUR. over 700 different panels Houseman Hegro 'the water people' catalogued, and special designs are no problem HOUSEMAN HEGRO LIMITED, to the EXPERTS The Priory, Burnham, Slough SU 7LS. ® Reg, trademark of GARDNER-DENVER Co. Telephone: Burnham (062 86) 4488. Telex: 848252. AUGAT LTD. I9a Regent St. Rugby. CV2I 2PE tel: -0788 75483 Please circle Reader Enquiry Number j for literature AUGAT N.V. 103 Bd. A. Reyers. Brussels 1040 Belgium PortalsWater'atrnent tel: —(02) 736.9399.

Electronic Engineering December 1976 101 - r't'r•'--- .1rneeriKipeeS

89 on enquiry carcellGH VOLTAGE CONNECTORS

The connectors shown here are an example of high voltage connectors manufactured by Reynolds Industries for a wide variety of applications. Typical are: laser power supplies, exploding bridgewire detonators and pyrotechnic devices, spark chambers, pholomultipliers, travelling wave tubes, cathode ray tube display systems, magnetron power leads, and high voltage power supplies for both ground and high altitude environments.

SERIES SOO HIGH VOLTAGE, HIGH ALTITUDE, COAXIAL CONNECTORS VOLTAGE RATING: 10,000 VDC* PANEL CONNECTOR: P/N 167-3771 CABLE CONNECTOR: P/N 167-3770LA

This area must be encapsulated when connector is subjected to reduced pressure, Uses 'U type Reynolds cable A complete line of subminiature high voltage coaxiar con- moisture. or voltages above 5 KVDC. P/N 167-2896 nectors and cable assemblies designed to operate at any \ pressure altitude at a rated voltage of 10 KVDC. Cable assemblies and cable connectors effect an altitude and moisture seal through use of internal seals which require no encapsulation. Panel connectors require encapsulation or shrink tubing at the junction of the terminal and the insulator.

• The voltage ratings shown are for limited service under steady-state oc conditions at sea level. Under these conditions, the connectors operate in the corona region, and therefore have a limited service capability.

SERIES 521 SAFE HIGH VOLTAGE, HIGH ALTITUDE, COAXIAL CONNECTORS VOLTAGE RATING: 25,000 VDC* PANEL CONNECTOR: P/N 167-3517 CABLE CONNECTOR: P/N 167 -4534

A series of high voltage connectors and cable assemblies Uses Reynolds cable RG-8/U rated at 25 KVDC mated, and designed to minimize the 2.560-51 0.750 OIA.-1, or AG 213/U

risk of electrical shock to personnel through the use of CORONA Fir 'recessed contacts. Both the panel and cable connectors BALL have recessed contacts and will stand off .the rated voltage of 20 KVDC in an unmated condition. The connectors (OPTIONAL) also feature e spring finger contact on the connector body

which assures a reliable ground circuit prior to engage- 3.940 4.027 ment of the center contact further reducing the risk of electrical shock. • The voltage ratings shown are for limited service under steady-state oc conditions at sea level. Under these 'conditions, the connectors operate in the corona region, and therefore have a limited service capability.

Represented in the United Kingdom by: REYNOLDS INDUSTRIES INC. AVIQUIPO OF BRITAIN LTD. St. Peters Road, Maidenhead, LOS ANGELES, CALIFORNIA U.S.A. 90066 Berkshire SLX 7QU. Tel: Maidenhead 34555.

90 on enquiry card PERFECT MATING with sNitiv-web.%.1

AUDIO CONNECTORS

NO LOST SCREWS MODERN STYLING Captive design insert Compact modern shape made of durable die- screw for fast simple cast zinc with satin assembly and disassembly nickel finish —can't drop out and get lost. compatible.with other makes. NO EARTHING PROBLEMS EASY TO WIRE Extra earth terminal The easy-open design and larger, electrically integral with shell uniquely designed solder cups cut automatically engages the wiring time in half. earth contractor of the mating shell IMPROVED FEATURES BIFURCATED CONTACTS 3-pole contacts ensure extra positive grip on mating contact pins, even under severe conditions of shock and vibration. F.W.O. Bauch Limited LATCH LOCK Now made of die-cast zinc for exceptionally long life and reliable operation. 49 Theobald Street, Boreham Wood, Hertfordshire,WD6 4RZ .INSERT STRENGTH New design grub screw and tougher plastic eliminates breakage problems. Tel:01953 0091 Telex:27502 _

102 Electronic Engineering December 1976 PRODUCT FOCUS connections between pcb's. formed by two parallel legs with Other devices include the Ban- bevelled tips, ensuring maximum tam range of circulars conform- spring loaded contact pressure ing to MIL-C-26482 and Flexlok, on the conductor. 463 flexible pc and flat cable con- Lemo's B range of self-latching nector. 453 connector offers excellent elec- Steatite Insulations, who trical and mechanical properties handle Chromerics Inc products, enhanced by an aesthetic ap- have available Cho-Strel and pearance. All components within Cho-Nector, which are one and the mating shells and the shells two dimensional discrete-path themselves are keyed to prevent conductive elastomers and a rotation, mismating and/or insert non-discrete path material called damage. 464 1250. Currently the electronic Smiths Hypertac recently an- watch market uses this material nounced a new high density for inter-connections but NASA connector (HCV). The range is developing a version of Cho- includes 0,5 to 1mm signal pins, Nector that will handle some co-axial power and filter pins 16 000 contacts/sq ins, for use and caters for up to 5000, 5A in an array or parallel processing contacts. Continuing the high computer. 454 density theme, a new 160 way pcb device provides 1,27 mm Aviquipo, who represent Rey- pitch with three rows of 15,24 nolds Inds. Inc in the UK, cater mm pins. 465 for the multi-pin hv connector The new Edgeblock BJ connectorlterminol from Pye eliminates area. Operating voltages up to the need for intermediate wiring UECL's range of modular edge connectors for pcb's are offered 15 kV dc at altitudes of 21 538 m factured by Positronic Ind. Inc, The AWP Group handle four with pitch sizes from 2,54 to (MIL-STD-202 Method 105 consisting of miniature/sub- connector manufacturers, Sar- 5,08 mm. These devices can be condition C) are available. RI miniature, rectangular, side- gus, Kings Electronics, PSP tailor made to individual custo- also produce hv co-axials rated mounting and pc-types. and AID Comps. The former mer requirements. Various con- between five and 10 kV dc. 455 They also act as distributors for of these companies has de- tact styles are available, includ- Winchester, AMP, Cinch and signed and developed a new Plessey offer amongst their ing cantilever (plain and stag- Amphenol. 459 range of multi-pin circular con- wide selection the Mk 14, 18 and gered), inverted bellows and nectors, type SPD. They will be 22 circular connectors; a com- switching. 466 available in four shell sizes, 18, prehensive range of rectangular ML Comps., are agents for 22, 28 and 36 with four sizes of Hughes Microelectronics and pc-types. Their rf co-axial LM Ericssons range of modular contact ranging from three to 35. range of connectors now in- types, series SMA, /B and /C, connectors. These are built up Kings Electronics produce high- cludes the new snap-lock device, BNC, TNC, N, HN, C and UHF from standard contact modules, density quick connect/release a quick connect/disconnect de- afford an improved cable/con- containing either 20 or 30 products, designed to replace vice aimed at bulk heat type nector assembly. Two unique contacts and combined into BNC type devices. PSPs contri- applications. It has one to three constructions exist, namely the connectors offering either one, bution is the T Et B/Ansley Blue way contact configurations with Wedge-lock and Wedge-eze, two, three or four modules. 460 Macs, flat cable/connector sys- either power or coax contacts, neither requiring combing or tem. Finally ALD offer the Heller- or amixture. Another series is the trimming of the braid. 456 man Deutsch RR series rear HAC-PAK range, a packaging Amongst Varelco's newer ad- Aveley Electric's range of rf release contact termination sys- concept allowing the designer to ditions is the series 6072, 2,54 devices from Rhode Er Schwarz, tem produced to EL2113 Pattern decide on aseries of connectors mm pitch modular connector, cover sexless rf devices with 602. 462 at the outset of his project along with the series 8223 two- impedances from 50 to 75 0, capable of fulfilling all his re- part device available with a 3M's connection option is the frequencies span from zero to quirements. 467 selection of contact terminating Scotchflex flat-cable and con- 18 GHz. Power handling capabi- techniques. The series 8257 nector system. By removing the McMurdo offer a comprehen- lities up to 9kW at 100 MHz and connector conforms to DIN connector covering and laying sive range of high density two 3,5 kW at 1G Hz are offered. 457 41612 and is available either in a the cable into the grooves in the part connectors, pc edge and discrete form or for metal back- cover a perfect alignment is strip connectors. Subminiature Siemens latest products include planes with avariation for press- ensured. The electrical reliability rack and panel, rectangular and a a mixed contact pcb connector fit into pcb's. 461 is guaranteed by the contact series of micronectors are also available with either 78, 60 or 42 available. 468 signal contacts and either two, Further information can also be obtained on connector four or six special contacts re- Hellermann Deutsch number products from the following organisations by encircling spectively. They are designed to amongst their latest introduc- the required reader service number. accept, in addition to small signal tions the following: the series contacts, individual af contacts AB Electronic Comps. Ltd 470 NSF Ltd 481 219, a two part connector for higher loading and/or a AMP of (GB) Ltd 471 Panduit Ltd 482 qualified to VG 95324 specs. variety of co-axial contacts Astralux Dynamics Ltd 473 Pye Connectors 483 The DCI range of underwater along with polarising keys. The Belling-Lee Ltd 474 Radiall Microwave Comps. connectors; high temperature other product is atape cable pcb Berg Electronics Ltd 475 Ltd 484 connectors in the series 991, /2 receptacle meeting series 2 Cambion Electronic Pdts. Ltd Radiatron Comps. Ltd 485 and /3, capable of working at DIN 41612 requirements, for use 476 Sealectro Ltd 486 350°C. Extensions have been with 48 contact plugs. 458 Flair Electronics 477 Souriau Ltd 487 made to the LL series of military Greenpar Electronics Ltd 478 Townsend-Coates Ltd 488 connectors, facilitating the use Tekdata offer a range of rack Invader Components Ltd 479 Vero Electronics Ltd 489 of crimped contacts with her- and panel connectors manu - Nimrod Electronics Ltd 480 Molex Electronics 472 metic receptacles. 469

Electronic Engineering December 1976 103 BICC-BURNDY Parr, St Helens, Merseyside WA9 1PR Telephone: St Helens 24000 91 on enquiry card

Limitation of design flexibility was acommon Production becomes more efficient and more connector problem. Until TRIM-TRIO. economical with TRIM-TRIO. Fewer contact TRIM-TRIO is aunique system that reduces types speed production with less tooling, longer these kind of complications in design. And in runs and fewer special skills. And there's a production. Once employed, it is alasting design comprehensive range of production tooling for decision. Once evaluated it gives you practically low to high volume needs. all the flexibility you need. Stock control is simplified too. And the reduced It's simple. Choose any from the three crimp number of TRIM-TRIO components cuts contact families and your choice can be used inventory costs. in amultitude of connector styles and sizes. So get the freedom of connector design that You can interface with wrapped and soldered only the TRIM-TRIO system can give you. And techniques without deviating from your original get all the U.K. based know-how behind you. contact choice. Plus the international resources associated with There's an expanding range of connectors which BICC-BURNDY. include circular plastic types with metal coupling rings. Low profile styles. Rectangular multipins for many applications. And low cost self TRIM mounting types. All constructed for outstanding SYSTEMATICALLY YOURS performance and reliability. TRIM for three ins we'll give you our •system NEW PRODUCTS

IR emitter Print heads efficient magnitude measure- one to 5000 psi. The device is all A new small area high radiance The EP101 miniature, drum ment. GenRad, Boume End, solid state from sensor to read- ir -emitting diode designed for print head offers a print format Bucks. 345 out. Options include a bcd fibre optics applications at 1,06 of 21 columns with 16 characters o/p, buffered analogue o/p and micron wavelength, has been per column. Print speed is 180 IR source manual or solenoid operated designated GAL103. This gallium lines per minute. Interfaces are Using aGaAsP on GaP chip, this vent facilities. Druck, Groby, indium arsenide emitter repre- available for driving the unit visible, near ir -source is opti- Leicestershire. 349 sents asignificant breakthrough from eight or 16 channel bcd mised for maximum efficiency at in optical fibre systems. Encap- i/p at ttl levels. Roxburgh 670 nm.wavelength. Designated Vi bration meter sulated in astandard S4 micro- Electronics, Rye, Sussex. 341 the HEMT 3300, this emitter is The PR9255 measures peak or designed for optimum coupling rms values of velocity in cali- Controllers to silicon detectors and plastics brated ranges from zero to five, A new series of indicating fibres. Axial radiant intensity is 15, 50 or 150 mm/s or uncali- controllers known as Transitrol typically 500 AN / steradian. brated up to 510 mm/s. The II has five basic types; an indi- Bandwidth is dc to 3 MHz. unit will work with absolute and cator, one and two limit sig- Hewlett-Packard, Winn ers h, relative active vibration trans- nallers and two and three Berks. 346 ducers with nominal 30 mV/mm position controllers. The instru- /s sensitivity. The nominal fre- ments operate on anull- balance Digital multi meter quency range of 10 Hz to 1 kHz principle. Inputs from single or The DMM51 features a 1p.V can be reduced by using external differential thermo-electric or sensitivity on dc (5 ranges); filters. Pye Un/cam, Cambs. 350 variable resistance sensors as 10 0/ on ac (4 ranges); 1 ma well as from transmitters with on the six ohm ranges with full Preamplifiers voltage or current o/p, are all autorange on all functions. Basic Three new low noise, high gain acceptable. Pye Ether, Steven- accuracy is 0,002% with a uhf preamplifiers for frequency wave stud package, these diodes age, Herts. 342 speed of 3,33 reading/s with groups A (470/581 MHz), B offer a combination of high 66 dB noise rejection. Integra- (615/717 MHz) and C/D (695/ modulation >200 MHz and Power supply tion period is 100 ms providing 860 M Hz), have been designated high radiance >10 W/steradian/ This power supply unit finds use >140 dB cmrr. Wessex Elec- the CM6051 series. The group crnt. The 50 micron diameter in conjunction with emergency tronics, Yate, Bristol. 347 A devices have again of 16 dB, emitting area is designed to audio and visual alarms. It pro- B 14 dB and C/D 12 dB. All provide efficient coupling of vides a 24 V dc, 5A regulated Coaxial connector three have typical nf of 5 dB, single fibres and an etched well o/p from 220/250 V ac mains at This high tension coaxial con- maximum o/p of 28 dB mV and 0,15 mm diameter is provided 50/60 Hz or 24 V dc, 4,5 Ah nector with ceramic insùlation, i/p to o/p impedance of 75/ohms for this purpose. Plessey Opto., from two 12 V sealed lead acid permits use up to 400°C and high Labgear, Cambridge. 351 Towcester, Northants. 340 batteries. Barkway Electronics, radiation usage. A test voltage of Royston, Herts. 343 9 kV can be withstood from the Load cells Drive systems centre contact. Designated This cell is fully waterproofed With an unformatted data capa- Admittance meter 103A028, it features an overall and gives precision performance, city of 3,2 megabits (single) or This versatile uhf admittance diameter of 13 mm and a typical non-linearity is +0,05% 6,4 megabits (double density), meter, type 1602B, has a coupled length of 78 mm. Seal- of fs, hysteresis being +0,03% the model 76 diskette drive pro- measurement capability between ectro, Portsmouth, Hants. 348 and non-repeatability +0,02% vides the user with the facility 20 MHz and 1,5 GHz. Typical of fs. The SSB is available in two for either IBM 26 sector for- accuracies of +3% are obtain- Pressure indicator capacities namely 100 and 250 matting or 32 fixed length able. The instrument is a nulling The DPI 100 digital pressure lbs. REL Equipment & Comps, sectors. The recording head is unit, measuring impedance and measuring instrument has an fs Hitchin, Herts. 352 ceramic/ferrite, with tunnel erase admittance in coaxial systems. It of 19999 and an accuracy of structure and average access to may also be used as a reflecto - 0,05% fs with fast response. Multimeters stored data is 164 ms. Data meter for SWR, impedance It provides a secondary pres- This 50 kO/V device incorporates Recording, Staines, Middx. 344 magnitude and reflection co- sure standard for ranges from an lcd controlled by the range

meet some of the family...... of 'hypertac' connectors that are now meeting the rigorous demands of avionics, telecommunications, electrical and nuclear energy, and the various Service ministries. The unique "hypertac" socket design ensures precise mating, or unmating, of all contacts throughout a range which includes p.vv.b. connectors, modular connectors, circular connectors, single pole connectors, rectangular unitors and the recently developed high density modular connectors which have 5,000 signal pin capability. Find out more about the most versatile electrical connector range available today by writing or 'phoning Barbara Butler on 01-452 3333 extension 4284. hyperlac

106 Electronic Engineering December 1976 NEW PRODUCTS

selector switch. The LCD900 voltage rating is 125/250 V dc. Slide switch to 160 V dc. The KP1834 range offers six cd -V from one to 1 kV; Major features of the range These miniature slide switches, has been extended to cover 100 five ac-V from 10 to 1 kV; four include a non-rotating movable series 200, offer two position to 470 pF at 160 V dc. The dc-A from 300 I.4A to 300 nnA; electrode, afixed position tuning control and are available in 11 KT1805 series offers capaci- an ac-A at 3A and a resistance screw and facilities for elimin- different versions. Typical opera- tances from 1000 pF to 0,068 range from 1 kto 1 mn. Quality ating dust or moisture hazards. tional characteristics include a uF at 63 V. The ceramic series Electronics, Lydd, Kent. 353 ITT Comps Group, Harlow, standard temperature range from are ideally suited to telecom- Essex. 354 munications operation. Steatite, Calculators —25 to +85°C and switching capability of up to 3 A at 125 V Birmingham. 363 Powerful, fast and accurate, the Frequency standard ac. Diamond H Controls, Nor- new 852, 4650 and 4660 range The type 2031 frequency stan- wich. 360 Pulse counters dard is atransportable source of An extension to the ET series of accurate reference frequencies. Prototype pcb's counters offers afive and 7-digit Two standard o/p are provided A new concept in prototype time and totalising counter re- at 10 and 1 MHz and the 'oven pcb's allows the user to go direct spectively. The latter device controlled crystal oscillator has from circuit diagram to com- features a counting rate of an aging rate of <5 x 10 10 /day pleted board without using 15 pulses/s for dc and 10 and <1,5 x 10 -7/year. Dymar chemicals. Blob boards as they pulses/s for ac. Various colours Electronics, Watford, Herts. 356 are known are initially available in drum configuration are avail- Indicators in 12 patterns, which, between able. Sodeco-Saia, Geneva, The M range of led indicators them, accommodate discretes to Switzerland. 364 ic's. P B Electronics, Saffron offer the combination of fast Circuit testers switching speeds, high relia- Walden, Essex. 361 These testers are designed for bility and low cost. Typical Solid state relays use with solid state circuits. The luminous intensity figure is 1,6 This range of ssr's includes anew LCI identifies logic level at any mcd at IF=10 mA with viewing type of gating circuit, giving point in a digital circuit. Indica- angles of 55°. These long-life high dv/dt ratings of 500 V/us, tion is via a tone, high or low devices are fully ic compatible making them ideal for high depending on state. The tester is and will operate between —55 inductive loads. The ac versions suitable for use on fet's, cmos to +100°C. Boss Ind. Mouldings, provide sp/no or nc o/p, whereas and ttl, operating at clock rates London. 357 the dc range offers, in addition, up to 5 MHz. Single pulses down Microwave transistor both single and dp, dt, non- to 200 ns duration will be of scientific calculators are aimed This microwave bipolar tran- bias, break before make switch- detected. The Cil, continuity at a cost effective price bracket sistor, model HXTR-6102, has a ing configurations. National tester aids the location of poor for consumer usage. Both the guaranteed nf of 2,7 dB at Semiconductors, Altringham, solder joints, dirty switch con- 852 and 4650 have accumulat- 4 GHz, with 2,5 dB typical. Cheshire. 362 tacts, etc., by indicating resis- ing memories whilst the 4660 Associated gain is 9 dB. Hew- has three separate fully address- lett-Packard, Berks. 358 Capacitors able memories. National Semi- Various new ranges of foil, Enquiry Service conductor Corp, Bedford. 355 Tone converters polypropylene, film, polyester For rapid access to further The CM1720 provides line de- and ceramic capacitors have information, use the reply Trimmers dicated touch tone to dial pulse been announced by this manu- paid card at the start of The Voltronic A range of pre- conversion for pabx and central facturer. The KP1835 polypropy- the commercial section. cision air dielectric trimmers applications. The unit features lene series spans 470 pF to Our R.E.S. department offers insulation resistance from one and two digit programming 0,031£F between 63 and 630 V provides same day turn- 10 8 Mû up to 150°C. Capaci- for stop dialling (single or dc. The KP1838 series of poly- round on all enquiries. tance drift is 0,01 pF; tempco multiple), wink start and release. propylene/foil devices have +50, +50 ppm/°C; la at 100 Danbury Consultants, Chelms- values from 100 pF to 0,1 uF MHz is 4000 minimum and ford, Essex. 359 with working voltages from 63 continued

92 on enquiry card

Type HPD connector, designed to conform to the forthcoming British Type HHD High Density Standards specification. iftittimi'itlltrinftft fte irrttftifteftil ft connector is the answer to miniaturisation and densification Type HMC , of electronic packaging. Modular Connector solves the equipment designers problem of obtaining special connectors quickly and inexpensively. HYPERTAC CONNECTORS Chronos Works, North Circular Road, Londqn NW2 7JT Telephone 01-452 3333 Telex 25847

ii reuistered business name of h SMIT eiS INDUSTRIES LIMITED

Electronic Engineering December 1976 1O7_ 95 on enquiry card We thirst to be first.

Since our foundation back in 1938, our introduced commercial interconnection system, development into one of the industry's leaders featuring 2.5 mm. and 2.54 mm. spacing, established in connector system design and production has anew standard in miniaturization. been punctuated with one first after another. So, with almost 40 years at the forefront we've For instance, Molex were first to introduce awealth of experience to draw on, in meeting the continuous chain-form round-pin and socket demands of industry today. type multi-way connector terminals for automatic And you can be certain we'll be the first to meet crimping — and they're still in volume production. them tomorrow. The first modular interconnection system was also ours. (It was this Molex lnconect system that introduced modular construction into the modern domestic t.v. receiver.) Molex were first, too, with free standing transistor and IC terminal sockets. And first with moiex afamily of commercial connectors, the 1991 series, specifically created to meet international requirements. \ \earlAFFORDABLE TECHNOLOGY Our Konektcon series, the first total systems Molex Electronics Ltd., approach to modular interconnection, is now the 1 Holder Rd., Aldershot, Hants. GU12 4RH. largest selling system anywhere. And our recently Tel: 0252 313131. Telex: 934658. 2482

110 Electronic Engineering December 1976 NEW PRODUCTS

Pulse generators layer (up to 20 layers), flexible Portable 'scope Current ratings available span This programmable pulse gener- and flex-rigid, manufactured to This dc to 25 MHz bandwidth four to 25 A/phase. Waycom, ator has been designed for ecl ESRO and CCT approval. Other portable oscilloscope, model Bracknell, Berks. 387 and other high speed applica- types of circuitry available in- 9386, offers asensitivity variable tions. The model E-H 1501A/129 clude hyper-frequency circuits. Bridge mixer offers facilities such as memory TSS, Camberley, Surrey. 381 This high performance, single read-out or optical isolation. The balanced, four diode bridge programmable o/p stage can Programmable mixer—the WJ-M29C—has a deliver positive or negative calculator frequency range from one to pulses with up to 2 V amplitude Thé PR100 has in excess of 30 18,5 GHz, and is both multi- and +1 V offset. The rise and pre-programmed functions, 10 octave and biasable. Conversion fall times are <500 ps at full independent memories with full loss is typically 12 dB with amplitude. Programmable fre- memory arithmetics and the from 10 to 50 mV/cm in 12 —10 dBm LO drive and +15 V quency is 50 MHz. Elex Elec- added capability of storing 72 calibrated ranges. Accuracy is dc bias. The unit features a high tronics, Henley -on -Thames, programme steps. The device is +3% and there are 19 calibrated isolation of typically >20 dB. Oxon. 375 rechargeable with a 10-digit ranges controlling timebase Watkins -Johnson, Windsor, accuracy with an eight plus two speeds from 200 ns/cm to 200 Berks. 388 Balanced mixer large led display. Commodore, ms/cm with a x 5 magnification This economical double Slough, Berks. 382 providing speeds up to 40 ns/cm. Power Darlingtons balanced mixer has been de- The 101,6 mm crt operating at A series of complementary power signed for rf signal processing Deflection yokes 6 kV ensures a bright display. Darlingtons, available as pnp or applications. The M-109 in- The C-9370 is intended for use Racal lnsts, Windsor, Berks. 385 npn types offer voltages up to cludes frequency ranges from in crt displays where excellent 100 V at 12 A throughout. The one to 500 MHz; typical con- geometry and repeatability at RAM systems BDX85 series are npn and version losses are 6 dB from one low cost is the requirement. This 16k x 20-bit memory sys- BDX86 series are pnp types. to 200 MHz and 7,5 dB from 200 Stator wound on a ferrite core, tem, organised into 16 000 Power dissipations range to to 500 MHz. Noise figures are designed-in geometric correc- twenty-bit words, is contained 120 W with high gain (minimum within +1 dB of conversion tion and good resolution are all on a single card. The NS3000-1 1000 at 5A). SGS-Ates, Ayles- loss. DC offset is typically +1 attributes of the device. Deflec- is designed for high speed bury, Bucks. 389 mV and maximum i/p power tion angles up to 90° are pos- operation, providing high re- 50 mW. Merrimac Inds Inc, sible. Sylvan Ginsbury, Roches- liability at low cost. Access time Digital voltmeter U.S.A. 379 ter, Kent. 383 is 280 ns with a read or write The model 8500A dvm, is a bus cycle time of 430 ns. Memory oriented, p.P controlled measure- Pressure transducer Tone receivers refresh can be implemented for ment system capable of register- The model 2900 pressure trans- The CM8822 and CM 8825 tone individual applications either in ing ac-V, dc-V, current and ducer features a solid state receivers are high performance, synchronous or asynchronous resistance by the addition of sensor, four element piezoresis- low cost modules developed for mode. The standard version tive silicon semiconductor applications where touch tone requires sources of +15, —5 and bridge, high o/p, etc. Ideal receivers are required. Both +5 V. National Semis, Bedford. Enquiry Service applications will be found in the devices interface with cmos and 386 For rapid access to further measurement of static and dyna- ttl. The units have 30 kû i/p Phase filters information, use the reply mic pressure in liquid and gas impedance and achieve low A range of three phase filters paid card at the start of systems. Bourns (Trimpot), simulation rates through multiple have been designed for the sup- the commercial section. Hounslow, Middx. 380 signal quality checking circuitry. pression of mains transients in Our R.E.S. department Current drain for applications in three phase power sources. provides same day turn- Circuitry data transmission is 10 mA when Attenuation from one to 300 round on all enquiries. A wide selection of pcb's are connected to a+12 V dc source. MHz is provided over the fre- available from this supplied in- Danbury Consultants, Chelms- quency range in both the sym- cluding double-sided pth, multi- ford, Essex. 384 metric and asymmetric modes. continued

96 on enquiry card TOTAL CRYSTAL OSCILLATOR CAPABILITY IP UD FAST DELIVERY FROM LYONS

Logic*Frequency compatible range clock 0.01 oscillatorsHz to 400 MHz Allr * ON * High-stability oven controlled crystal oscillators VECTR. *Voltage controlled crystal oscillators (VCX0s) EicscelonstaniteiveUsK. Illir * Temperature compensated crystal oscillators (TCX0s) Repr *VHF crystal oscillators LYONS INSTRUMENTS * Laboratory frequency standards Hoddesdon Herts EN11 9DX Telephone 67161 Send for full details today to Telex 22724 A Claude Lyons Company

Electronic Engineering December 1976 111 -r."e,;7.e

NEW PRODUCTS plug-in modules. There are five include complementary o/p at Amplifier systems The device is cmos and ttl dc voltage ranges from 11J.V to standard ttl levels. Salford Elec- This new twin channel ac compatible. Teknis Electronics, 1,2 kV with a basic accuracy of trical Insts., Heywood, Lancs. carrier amplifier system is for use Slough, Berks. 398 +0,001%. The ac-V is measured 393 with transducers and strain with one or two options; the -01, gauges. Full scale o/p is achieved Opto isolators which is an average converter Switching modules from i/p signals as low as 2,3 mV The series includes 3N243, /44 and the -02 offering four terminal These units are designed on a up to 5V with a linear over- and /45 types. They offer resistance measurements from single module per channel basis, range of 100% and digital read- guaranteed minimum current 10 SI fs to 100 ma. AC/dc eliminating cross channel inter- out up to +1999 digits. The transfer ratios of 15, 30 and 60% current measurement, from 1 nA ference. The range includes c/o built-in oscillator provides 5V respectively. All devices feature to 1,28 A are enabled by using and cross over modules, spare at 5 kHz allowing dynamic sig- 1 kV isolation and will withstand option -03. Fluke International, single and multiport modem nals up to 500 Hz to be recorded. htrb at 125°C and 20 VCE. Watford, Herts. 390 switches and a matrix switch for San gamo Western Controls, Norbain Opto -Electronics, Read- patching computer ports into an Bognor Regis, Sussex. 397 ing, Berks. 399 Power supplies equivalent number of modems. The G RS range of single o/p, No/ton Communications, Wal- Acquisition systems • Servomechanisms high power density linear regula- tham Cross, Herts. 394 This data acquisition system, This range of synchro actuated tor supplies are available in three designated DAS1128, features a direct drive servomechanisms different case widths. A wide Strain gauges high speed 15 I.Ls 12-bit adc, an will operate from supply fre- range of o/p currents and vol- A miniature electric resistance s/h amp, precision reference, quencies between 50 and 400 tages are offered with versions strain gauge that can measure Hz. Output torques between available with edge connector or strains at temperatures up to three and 50 oz/in with posi- terminal block termination for 1093,3°C has recently been tional accuracies of 10 arc mins designer appeal. All units have announced. The gauge is appli- are possible. Within the housing dual i/p, built-in over voltage cable in hostile environments at is a high efficiency dc torque protection and re-entrant over critical stress locations of high motor and a synchro control current limit. Gresham Lion, temperature energy generation transformer mounted on asingle Feltham, Middx. 391 systems, space vehicles and shaft. Servodata, Newbury, hypersonic aircraft. It has been Berks. 400 Capacitors developed from an alloy and These metallised polyester and drawn into wire two-thirds the high stability buffer-amp and a PLL circuits polycarbonate capacitors are diameter of a human hair. 16-channel multiplexer. Non- The SP8760 multi-function cir- available from 1 nF to 22 ;IF with Batelle Columbus Labs., U.S.A. linearity temperature coefficient cuit finds use in phase-locked tolerances to 0,5 and 1% respec- 395 is 2,5 ppm/°C and 8 ppm/°C for loop systems. It incorporates a tively. Temperature range spans high stability, +0,012% of fsr crystal oscillator and divide-by- —55 to +125°C. Torno Electro- Thyristors relative accuracy at 33 kHz four scaler, a digital phase/ nics, Attenborough, Notts. 392 The SKT7OF, /90F and 110F throughput rate. Power require- frequency comparator and a low ranges of thyristors, due to their ments are 15 V at 40 mA, —15 V frequency two modulus divide Clock oscillators high di/dt ratings, can be used at 70 mA and 5V at 250 mA. by 15 or 16 prescaler. This This device, the 0£1453, is at frequencies up to 10 kHz. Analog Devices, E. Molesey, device may be used with a offered in two versions, the They have critical di/dt values of Surrey. 401 prescaler to phase lock single -/1A-1 for frequencies from one 800 Affis with available turn- frequency transmitters or re- to 5 MHz and the -/1A-2 from off times from 15 to 40 p.s with Converters ceivers in the hf, vhf or uhf bands. four to 10 MHz, both suitable for reapplied dv/dt of 200 V/p.s. The model A8402 v-f-v conver- The two-modulus prescaler will zero to 70°C. Operating powers Average forward currents from ter requires one supply rail in the operate to 18 MHz typically and are low, 200 and 100 mW at a 87 to 140 A and peak reverse range +4 to +18 V and has a the phase comparator has only a supply voltage of 5V. Other voltages from 200 to 1,4 kV are linearity of ++0,05% up to 30 ns zero phase pulse width. features of this plastics encapsu- available. Semikron, Hertford. 10 kHz and +0,1% up to Plessey Semiconductors, Swin- lated quartz crystal oscillator 396 100 kHz which is its full range. don, Wilts. 402

Keep to the connectors you know At Ferranti we're keeping to the high standards we set ourselves right at the start. That's why so many people choose Ferranti connectors. Connector Capability Pitches of .100" (2..54mm)(modular connector), .150" (3.81mm), .156" (3.96mm) and .200" (5.08mm). Non-porous gold plating on the contacts—or gold flash if you wish. Terminals for wire wrapping or soldering. And avariety of end feet.

sass asammuisan 11110-11110131117111111 11111111111111 Mai

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112 Electronic Engineering December 1976 1 NEW PRODUCTS

Electrolytics Reference diode Operational amps three binary coded o/p models Two new ranges of computer A new linear ic, —6,9 V refe- The models A970 and /75 op- with resolutions of eight, 10 and grade aluminium foil electrolytic rence diode offers a dynamic amps are wideband devices 12-bits and a bcd-coded o/p capacitors conform to IEC 103 impedance two orders of magni- featuring high slew rates, low model with a resolution of three type 1 requirements. Voltage tude less than discrete Zeners. bias currents, high i/p im- ranges span 6,3 to 250 V with The LM129 operates over a 0,5 pedances and high cmrrs. The capacitances from 68 to 470 000 to 15 mA range. Long term A970 has a gain bandwidth of mF. Both types are designed for stability is typically 20 ppm 100 MHz and an open loop gain professional usage. Dean Elec- whilst noise is guaranteed to be of 95 dB. The A975 offers aslew tronics, Ascot, Berks. 406 <2011V. Dynamic impedance is rate of 80 Vffis whilst both units one ohm. National Semis., Bed- have i/p impedance of >100 Ann Clock oscillators ford. 403 and operate over a temperature The model CO-238T compatible range of zero to +70°C. Hybrid clock oscillator is available at any Systems, Camberley, Surrey. 409 frequency in the range three to PCB relays 20 MHz and incorporates a The MHP range features an im- Alphanumeric display proved cover and base/blade tuning adjustment for accurate This 7x 5 dot alphanumeric led support, 5 mm contact pin spac- setting (+0,0001%, 1ppm). The display features 17 mm high ing, large contact area and device operates from 5V dc characters and has integral mos stronger contact blades. This bcd digits. Maximum conversion providing attl compatible square shift registers for serial feed type of device has SEV and times are 1,8, 6and 24 ms for the wave o/p with stability electronic drive systems. Bright- other approvals and its AgCd binary coded models and 12 ms > +0,0025% over zero to 70°C. ness is controlled by asingle dc- oxide contacts give lifetime for the bcd unit. Datel, Basing- Lyons Inst., Hoddesdon, Herts. V and any number of displays can figures >500 koperations when stoke, Hants. 412 407 be controlled by one clock and switching 5A at 250 V ac. one data line. Either red or green Modulation meters Ouiller Comps., Bournemouth, Marking kit emission is available. ITT The AMM has been designed to Hants. 404 This cable marking kit, marketed Comps., Harlow, Essex. 410 simplify modulation measure- under the name of Pentronics, contains ten rolls of white crepe Switching sources Bipolar circuits tape each marked with bold The SOL series of direct off-line Five new 2900 family compo- numbers, letters or symbols and nents are now available comple- switching mode power supplies, backed with high-tack adhesive menting the Am2901, 4-bit p.P offer efficiencies in excess of suitable for temperatures of up to 70%; line and load regulations of slice and the Am2909 micro- 148°C. The tapes come housed 0,05% +5 mV; ripple and noise '7.. programme sequencer. The 2905 in a feed-out container. Bow- ments made in developing, pro- <2 mV rms (10 mV pk-pk) and is a 4-bit bus transceiver; the thorpe Hellermann, Birmingham. duction testing and the servicing low rfi. Output resolution is 2906 is also a 4-bit transceiver 413 of fixed or mobile communica- with parity. The 2907 is similar <30 mV and internal protection tions systems. Am and fm to the /06 with the two way shuts down the source when the measurements are possible over multiplexer at the i/p to the bus heat sink temperature exceeds the range 1,5 MHz to 2 GHz. On driver register eliminated, to 110°C. Coutant Electronics, Enquiry Service the fm, five deviation ranges are allow for compact packaging. Reading, Berks. 411 For rapid access to further provided from one to 100 kHz fs. The 2918 is a general purpose Information, use the reply AF bandwidth is selectable, the 4-bit register with two sets of AID converters paid card at the end of response being dictated by ac- o/p; ttl and three state. The final A series of monolithic adc's the commercial section. tive filters providing standard or product, the 93415 is a1024 x1 - featuring excellent linearity and Our R.E.S. department psophometric weightings and bit fully decoded ram for use in the ability to operate with 20 mW provides same day turn- de-emphasis correction where high speed and control stores. power drain from ±5V dc round on all enquiries. needed. Famell Insts., Wetherby, Raytheon Semis., Harlow, Essex. supplies, has been designated Yorks. 408 405 ADC-EK. The series consists of continued

97 on enquiry card t I As well as edge connectors Ferranti offer multi-pole low Distributors: Giltech Components Ltd. 22 Portman Road, force connectors with achoice of 35, 50, 70 or 91 contacts. All with Battle Farm Industrial Estate, Reading, Berks. RG3 lES low spring rate for easy insertion and withdrawal. Tel: 0734 582131 Contact Connector Sales, Ferranti Limited, Professional Components Department, Dunsinane Avenue, FERRANTI 1Dundee DD2 3PN, Scotland. Telephone: 0382 89321Telex: 76166. the better connector '-. 711114110117- 111111.1 1411111111111

Electronic Engineering December 1976 113 lr'lerrtler,., Pee.MNINeWzrelf)79..r - - , , 105 on enquiry card 106 on enquiry card Cost-saving Crimper 3,600 terminals-an-hour output max. ii ( UK price Big production economies with the £58.70 Hollingsworth H27Q tape-feed Plus VATand P&P automatic crimping machine, WIDE BAND AUDIO which can also be operated - SIGNAL GENERATOR manually. a high accuracy solid state High-speed and portable, sine/square wave generator weighing only 34 lbs, it with 600 ohm attenuator handles insulated, non- output or low impedance output delivering 3 watts insulated "U - (open) into a 5 ohm load. barrel, insulation- grip, metal-grip and slip-on terminals. Also butt splices in all 26-4 AWG sizes/0-1 mm 2-

25 rnm 2 made by Hollingsworth. UK price £54.50 Plus VAT and P&P HIGH IMPEDANCE AC/DC MILLIVOLTMETER Loose piece (The Modern equivalent of terminals the Valve Voltmeter) an AC/DC wide range meter and hand with 20 scales covering 1.2 tools also mV to 400 volts FSD available. incorporating a power scale in decibels, LINSTEAD ®TERMINALS LIMITED MANUFACTURING CO LTD Burwell Trading Estate, Leatherhead Road, ChessIngton, Surrey. Tel: 01-397 9233/4. Telex: 929382. ROSLYN ROAD LONDON N15 5JB ENGLAND Tel; 01802 5144

69 on enquiry card INVADER COMPONENTS LTD New, wafer thin, 700 series touch keyboards -the answer for performance and low price

Invader Components announce the availability of a new Series of elastic diaphragm touch sensitive keyboards Designed to be the ultimate in low price, flexibility and performance the new 700 Series are ideal for communications, appliances, automotive and unlimited other applications. The new Datanetics keyboard can be produced in virtually any size, shape, key spacing, colour etc. and the proven elastic diaphragm switch concept ensures exceptionally long life. Keyboards and Keys from: INVADER COMPONENTS LTD 30 TRIBUNE DRIVE •TRINITY TRADING ESTATE •SITTINGBOURNE •KENT ME10 2PG Tel: Sittingbourne (0795) Telex: 965313

114 Electronic Engineering December 1976 , 10-weepoiret,, .•

100 on enquiry card TRANSIPACk 1 NO BREAK POWER SUPPLIES NEW 2000 SERIES - FOURTH GENERATION 1KVA TO 200KVA 24 HOURS WORLDWIDE SERVICE 2 YEARS' GUARANTEE AVAILABLE BRITISH MADE VISIT US AT HASTINGS AND SEE OUR STATIC IN CENTRE

TYPICAL TRANSIPACK TYPICAL NO-BREAK POWER SUPPLY TRANS/PACK U.P.S. AS DELIVERED TO C.E.G.B. FOR COMPUTER APPLICATIONS

Sales and Labormones INDUSTRIAL STANLEY ROAD •• BROMLEY BR2 9JF KENT. ENGLAND Telephone: 01-460 9861/5 TS Telegram.. TRANSIPACK. BROMLEY Telex: 896071 LIMITED Factory THEAKLEN DRIVE TRAWIPACIe PONSWOOD INDUSTRIAL ESTATE HASTINGS. SUSSEX. ENGLAND Telephone: Hastings 427344

Electronic Engineering December 1976 115 " 94, ,, :a7 /9ere leCier.

102 on enquiry card 98 on enquiry card i„, (§) range of best OXLEY connections A Oxley Connector/Test Point The Design Award winning Oxley Snaplox® connector/lest point is an addition to Oxley's wide range of thumbwheel connectors, which clicks 'on' and pr,r - 'off' but if pulled sideways by acci- :. ''''. dent ' beyond a ggenerous angle, *L' . detaches itself without damage. „., . Two spills—stand-off or lead through switch —are available. The flying socket, PTFE insulated, spherical spring contact, is available in eleven stànd- ard colours. The Snaplox® incorporates many features and information is more... is available on request.

,,e, Oxley 'Snale' Printed Circuit Connectors -.4! Being tapered and micro-machined with serrations and splines, OXLEY 'Snale' Printed Circuit Connectors have a very high resistance to ex- traction and rotation and at the same time accommodate themselves to wide .hole tolerances (sizes 0.040" — 0.050"). The ease with which they ‘, can be assembled results in their 1, • \ ; ...>"-- wide use in printed circuit boards as test points, component supports .,„,...... '.41,.% „I and connection points.

Oxley 'Barb' Cone-Lock Plugs and Sockets 11 ,The OXLEY 'Barb' Cone-lock range 4p. 1 of plugs and sockets provide a wide t range of connectors incorporating , dispersion quality PTFE as the in- 1 1 1 sulating medium. The range covers a I sub-miniature version type 0.55mm for chassis mounting holes 2mm diameter to the large 4mm instrument 5- (7- types, having 8mm diameter mounting holes. Available in our very attractive range of colours.,

Oxley Printed Circuit Sockets They are designed for direct mounting on standard 0.1 module printed, •.' circuit boards. The mounting is ar- ...or less thanyou think ranged so that test probes may be - inserted in a plane parallel to the printed circuit board, thus permitting MORE in terms of Options, including output close stacking of circuit boards. Sockets may be supplied in 1 to 12 codes, wheel colours, special legends and five ways and are available in our stand- • - basic styles with many other factors which ard colours. Vertical mounted plugs and sockets designed for 0.040" PC will give you greater versatility. mounting are also available. LESS in terms of Cost, panel space, delivery Oxley Special Purpose and engineering time, because you could Plugs Er Sockets probably fill your particular réquirement with Used for a wide variety of chassis just one call to Cosmocord. mounting and printed circuit mounting applications. Special types include a stackable version 50P/156/S which Switch on to Cosmocord-Stolec and see for provides multiple lead-outs in combination with standard sockets yourself. 50S/156. The upper half of the plug is female; a slit in the socket is reinforced by a PTFE body, the lower half being a plug to fit the socket. A number can be stacked upon one another for test points, etc. Range of colours.

OXLEY (ID Oxley Developments Co. Ltd. COSMOCORD-STOLEC ULVERSTON •CUMBRIA •LA12 9OG •ENGLAND - Cosmocord Ltd. Eleanor Cross Road, Waltham Cross, CABLES OXLEY ULVERSTON •TELEX 65141 .TELEPHONE: 0229 52621 Hertfordshire EN8 7NX Tel: Lea Valley716666. Telex 24294

116 - Electronic Engineering December 1976 iirr ele%Ce,e1. '--777-7V/U-77,717

103 on enquiry card

NEW PRODUCTS

Diodes Isolators The low forward voltage rating (0,85 V) The OPI 6000 is available in a six pin and fast recovery characteristics of a dil package and features 1,5 kV dc new family of diodes, BYW29 to 31, i/p to o/p isolation with an o/p capabili- improve the o/p efficiency of inverters ty of 300 V dc break down. It is com- and switched mode power supplies. A prised of a GaAs ir -led and an hv npn reverse voltage rating, up to 150 V, photo-transistor. Guaranteed maximum enables an improved efficiency in hv o/p leakage current is 100 nA with a supplies. Mu/lard, London. 414 collector emitter voltage of 200 V. Saturation voltage for the o/p * tran- Dielectric testers sistor is 0,4 V with an i/p current of The TUPD series of testers have rated 10 mA and o/p of 0,5 mA. Norbain o/p voltages of three, six and 10 kV. Opto -Electronics, Reading, Berks. 420 Power ratings are 600 and 1 kVA. Besides insulation testing with high Diodes ac-V the testers include capabilities for These diodes, type PMD500, are fault burning and locating with currents capable of operating equally well as Series '200' up to 0,2 A. Routine production testing zero-bias detectors or high sensitivity Momentary, Locking, Interlocking, is facilitated by the leakage current mixers over the entire frequency range Cancel/Interlocking types. Barred signalisation with adjustable levels 12,4 to 18 GHz. The junction is formed Access and Blocking facilities. ranging from three to 20 mA. Statomat- such that the detector sensitivity is Up to 6 pole changeover. Micafil, Rugby, Warks. 415 —56 dBm at zero-bias, thus eliminating dc drift caused by biasing. Overall Fixed attenuators single side band nf is 6,2 dB over the The 6534 series of high quality 50 frequency range. Tranchant Electronics, fixed attenuators, operate from dc to Hampton, Middx. 421 18 GHz with mean i/p power rating of 5 W providing a choice of attenuations Rectifiers from three, six, 10 or 20 dB. The devices These glass and plastics technology, use resistive networks giving accurate rugged low power rectifier diodes are insertion loss and vswr at all frequencies available with current ratings between within their specified range. Marconi one and 3 A. An important feature of Inst., Stevenage, Herts. 416 the Superectifier is the brazed rather Series '400' Multi-reed key with optional than soldered junctions and leads. illumination. 65 gm or 300 gm Microwave transistors The unit will withstand temperatures as These low cost, high power microwave operate force. Collapse or high as 600°C. Distronic, Harlow, non-collapse actions. transistors operate at a frequency Essex. 422 range of 1,5 to 2,3 GHz. The devices are i/p matched, gold metallised with Character generator overlay emitter site ballasting. Output The type 2608 CNO040 is a1 k8 mos/rom powers range from five to 30 W with programmed to give the fully approved an option of 24 or 28 V. Tranchant teletext ,character font, le 7 x 5 upper Electronics, Hampton, Middx. 417 and lower characters. Features include static operation (no clocks) ; an Photodiodes access time of 650 ns; single power Four new silicon avalanche photo- supply 5 V; ttl compatible i/p and o/p; diodes find use in laser detection, 400 mW power dissipation; tri -state Type 5 ranging, optical communications and o/p; n-channel silicon gate technology Reed Key for standard and high speed electro -optic switching. and a standard 24-pin package. terraced keyboard applications. Three of the devices, the C30817, Mu/lard, London. 423 Wide range of key tops. -/84 and -/95 are supplied in TO-5 cans with a useful photosensitive area Wattmeter of 0,5 mm'. The fourth device the The model M2104 recording watt- C30872 has a larger area of photo- meter, comprises a solid state transdu- sensitivity, 7 mm'. The types -/17 cer having a dc o/p proportional to ac and -/72 have spectral ranges ex- power consumption. The dc o/p of the tending from 400 to 1100 nm and rise transducer is recorded on pressure and fall times of 2 ns. The -/84 version sensitive chart paper. Several standard has a high modulation capability up to ranges are available between zero and 400 MHz and a rise and fall time of 40 kW and zero and 1600 kW. Channel Dialight '554' 1 ns. RCA Solid State, Sunbury-on- Electronics, Seaford, Suseex. 424 A new competitively priced Thames, Middx. 418 illuminated key with matching indicator in identical package. Capacitors The RNRC range of metallised poly- Enquiry Service carbonate capacitors have ranges ex- For rapid access to further tending from 0,01 to 151.1.F. The dc information, use the reply working voltages span 63 to 400 V. paid card at the end of Pye TMC -Components Ltd., Working temperature ranges cover the commercial section. Controls Div., Exning Road, —55 to +85°C and have a 0,3% Our R.E.S. department Newmarket, Suffolk CB8 OAX Tel: Newmarket (0638) 3451 dissipation factor measured at 1 kHz. provides same day turn- Telex: 81245 Nortronic Assoc., Nantwich, Cheshire. round on 'all enquiries. 419 11 Electronic Engineering December 1976 117 re-

90 on enquiry card

Increase your standard of living

ARE YOU AWARE that the purchase of a retail business - Le. a modern Foodstore with sub Post Office or a Newsagents & Confectioners - is an investment over which you have personal control and from which you can expect to receive not only a substantial income, but one where enterprise and personal effort will bring rewards far in excess of those attainable in the role of an employee ?

ARE YOU AWARE that a house in itself is entirely unproductive, but by investing the proceeds, for example £15,000 in cash plus an easy payment loan you could obtain a business that would produce over £10,000 p.a. clear profit together with virtually cost free private accommodation, Within 2 or 3 years the purchase of a second business would be quite practicable during which time your assets would have at least doubled and once again, the purchase of a private house could be achieved out of the profits, if desired.

Your introduction to the many hundreds of businesses currently available can be found in Daltons Weekly, price 10p from newsagents. Dallons Weekly The Shopwindow for Shops and Businesses

101 on enquiry card of choice That's what's important to us at Optima. And that's why Optima cabinets and cases come in more sizes and colours than any other kind you can buy. With Optima you get 11 different colours to choose from, in fact. And hundreds of different models and sizes. Not to mention agreat long list of optional features like rack adapters and perforated panels and tiltstands and spring-loaded handles. In other words, you can have any enclosure, the way you want it. That's what freedom of choice means. And that's what Optima means, too.

Optima®OPTIMA Enclosures, adivision of Scientific.Atlanta. Inc. Macmerry, East Lothian, EH33 1EX, Scotland Telephone Tranent 610747 Telex 72623

118 Electronic Engineering December 1976 107 on enquiry card WheII size presents aproblem

-the MN7100 8-bit, 8channel data acquisition system

New to the UK and available from Tranchant, the MN7100 is the first complete data acquisition system offered in hermetically sealed, 32 pin dual-in-line package.

It's small size and low power consumption makes it ideally suited to awide variety of process control applications and many others including: Aerospace, Nuclear Power Generation, Hospital Patient Monitoring. Check the following features and you'll see just how much the MN7100 offers: * 8-bit resolution ± 1/2 bit linearity * ±15V and + 5V Power supplies * Microprocessor compatible *Adjustment-free * 90,000 conversions/sec * Random or sequential addressing * 8channels expandable to * Complete multiplexer sample and 256 channels hold AID Converter controlling logic Contact Tranchant today for adata sheet on the MN7100 which Is also available in extended (-25°C to + 85°C) and full military (-55°C to + 125°C) temperature ranges. tranchant electronics (uk) limited Tranchant House 100a High Street Ev1.7 Hampton Middlesex TW1 2ST Micro Networks Corporation Tel: 01-979 0123.

108 on enquiry card

Sanwa precision circuit testers 1. BX-505 •Fast-response, 241.2A movement — fuse & diode protected with high resolution factor (0.4pA/ Big on features. Bigger on selection. scale division) •Revised scale marking — intermediate readings readily determined 2. U-60D •44p.A movement — quality performance, diode protected •Stable ACV measurement — solid-state rectifier & enlarged frequency coverage 3. SP-10D •Easy operation — multiposi- tion rotary selector switch & well-lighted scale •Stable ACV measurement durable diode rectifier 4. N-501 •21.1.A suspension movement 0.05mA/1mV resolution •Double protection — fuse Si diode 5. CX-505 •16.5/IA movemgpt — varistor protected & 50k1Z/V for DC *Capacitor tester — push-button operation with solid-state oscillator built in 6. PDM-500 (Insulation Tester) *Battery operated — 3 small- size 1.5V batteries built in •Push-button operation —pointer Sole Importers in U.K. calibration & insulation test 7. CAM-300D (Clamp Meter) Quality Electronics Limited •Two scales, front and bottom, for reading convenience 24 High Street, Lydd, Kent, TN29 9AJ •Specially-designed,scissor-action Telephone: LYDD 20252 Telex: 965265 PlU9LTIIT1EISTERg core arms Electronic Engineering December 1976 __119 NEW DATA

The book, Electromagnetic horn The book Visual display units, £7, is A brochure has been published covering A high resolution low light level tv antennas, edited by AW Love contains aimed at users of computers who either the full range of fluid control equip- camera designed to operate all 82 pages to provide background on employ or intend to use VDU's to ment manufactured and marketed by Westinghouse 25 mm secand ebs fundamental theory and to give practical enhance their systems. IPC Science Hymatic, Redditch, Worcs. 265 camera tubes is the topic of a new information on the applications of horn and Technology Press Ltd, Guildford, technical bulletin. Westinghouse, Wind- antennas, £8,25. John Wiley and Sons Surrey. 257 Sealed nickel cadmium cells and sor, Berks. 272 Chichester, Sussex. 251 batteries are subjects of a leaflet from Fact sheets are available on the range of Tadiran which are marketed in this A new brochure available from Data products from Boss Industrial Mouldings country through Stanley Palmer Ltd, Recording Heads describes the activities GDS sales has just released its new Ltd including breadboards and plastic East Molesey, Surrey. 266 of the company at its factory which catalogue intended to interest en- and diecast boxes, Boss Industrial produces digital magnetic recording gineers and contains shortform data on Mouldings, London. 258 heads. Data Recording Heads, Egham, Computer Automation has published the products available from the Surrey. 273 company. GDS Sales, Slough, Berks. Information is available on the micro- an eight page colour brochure which explains the company's SyFA de- 252 wave bonded packages made by Teradyne Components has produced a Exacta circuits. A brochure can be centralised data processing system, CAI, Rickmansworth, Herts. 267 48 page technical information booklet obtained from SIC Ltd, London. 259 on the company's module library A leaflet is available on the Karl Suss which is a standardised electronic model MJB 55 production mask A leaflet describes aportable bin system Motorola's cmos data book is available packaging system. Teradyne, Cam- aligner which can handle slices up to especially designed for small assembly from the company at a price of £2,50 bridge. 274 127mm diameter and substrates up industries, so if you want to store it— including postage. Motorola, Wembley, to 127mm square. Epak Electronics, bin it. Noronix Ltd, London. 260 Middx. 268 A mini series of ic pluggable packaging Reigate, Surrey, 253 assemblies that measure as little as The thick film hybrid integrated A four page leaflet is now available from 123,4 x 111,3 mm is described in a circuits capability of Welwyn Electric Broyce Control has produced an eight LC Automation giving details of a leaflet from Garry Manufacturing, is described in a four colour brochure New Brunswick, USA. 275 page general and technical leaflet range of projectors, receivers, photo- from the company. Welwyn Electric, which covers about 5000 timers electric controls, timers and electronic Northumberland. 261 manufactured by the company, Broyce counters. LC Automation, Manchester. A leaflet outlining Rediweld Plastics Control, Brierley Hill, West Midlands. 269 service as suppliers of plastics 254 Three Permanoid leaflets cover a mouldings, includes all the common range of pvc flexible and lightcords, The second edition of the discontinued engineering plastics. Rediweld, Craw- pvc equipment wires and silicone diode data book can be obtained from ley, Sussex. 276 A technical specification bulletin on the rubber wires. Permanoid. Manchester. London Information at £19,70 (single Medilog recorder for a physiological 262 issue). The mechanical and electrical The 1977 edition of Hi -Fi Year Book data system for ambulatory monitoring characteristics from 24108 discontinued contains 500 pages and details on all is available from Oxford Instruments, A four page leaflet is available on the devices are listed. London Information aspects of the Hi -Fi world. £3. IPC Oxford. 255 Edgeblock BJ edge connector and Ascot, Berks. 270 Electrical Electronic Press, London. 277 screw terminal block from Pye Con- A booklet entitled "Employing staff" nectors, Biggleswade, Bedfordshire. 263 The telematic 2000 push button private Part of Data I/O customer service in- by Mr MJ Boella is one of a series automatic branching exchange has cludes the publication of aprom com- intended to help owners of small A shortform catalogue from Deltron been introduced by Telephone Rentals parison chart which provides essen- businesses to overcome the problems describes its range of components and is described in a leaflet from the tial data on every prom currently of employing staff. Department of including plugs, switches and en- company, Telephone Rentals, London. manufactured. Detail°, High Wycombe, Industry. London. 256 closures. Deltron, London. 264 271 Bucks. 278

For every viewpoint.

120 Electronic Engineering December 1976 Ilr"" NEW DATA

ITT Components Group has issued a56 recently developed frequency changers Practical electronics project building ceedings LOA symposium, Copenhagen. page illustrated catalogue covering its and their applications. John Wiley and is the latest in the series of constructors 298 range of relays and counters, ITT, Sons, Chichester, Sussex. 285 guides from Newnes Butterworth, Harlow, Essex. 279 Sevenoaks, Kent. 292 Profile is the name of ITT's house Yet another London Information data journal with many topics of interest in both general and technical terms. Another London Information data book book comes in the guise of linear ics Information is available on the Capable ITT London. 299 on optoelectronics is claimed to be which can be obtained at a price of 4000 family of minicomputer based 40 per cent larger than last year. It £35,05 for a year's subscription which automatic circuit board testers from comprises two issues, London Infor- computer Automation, Rickmansworth, Multi-colour stikons are the subjects can be obtained at a price of £49,45 of a short brochure from Bishop for a year's subscription. London mation, Ascot, Berks. 286 Herts. 293 Graphics, California, USA. 300 Information, Ascot, Berks. 280 A brochure from Tally describes the A product note has been produced by Power system transients, £10, gives a fully plug compatible T2000 line Zehntel on the company's automated The 1977 Hewlett Packard catalogue detailed description of the mathematical printer interface package for the test equipment known as the trouble- contains information on awide range of methods which may be applied to the PDP11 minicomputer. Tally, Reading, shooter 400. Zehntel, BF/ Electronics, products including oscillators, re- calculation of fast transient over- Berks. ' 287 London. 294 corders and medical instrumentation. voltages which occur in power system Hewlett-Packard, Winnersh, Woking- networks. Peter Peregrinus, Stevenage, Holden cords has a leaflet describing ham. 281 A four page application note is available Herts. 301 its range of cables and wires which on a photodiode/amplifier com- can be made to customer specification. bination made by United Detector Information is available on ate equip- An autumn issue of AGA Nay Aid Holden Cords, London. 288 Technology. The leaflet can be ob- review deals with teso major light ment ranging from programmable tained from Rofin, Egham, Surrey. 295 installations, for fog detector signal system modules and subsystems to Copies of two new ASEA publications systems that the company has in- complete semiconductor ate such as have been received in the United King- The Euromicro newsletter is intended to stalled. AGA Navigation, Bientford, the E-H 1100 bench top wave-form dom. One is the ASEA journal vol 49 facilitate the international flow of in- Middx. 282 analyser. Elex Electronics, Henley, no 3, the other is the 40 page pamphlet formation in the field of microproces- Oxford. 302 entitled ASEA Today which covers the sing and microprogramming. Infor- A brochure is available on the range of company's major product areas. ASEA, mation can be obtained from Warren More ate equipment in the form of moving coil meters including centre London. 289 Spring Labs, Stevenage, Herts. 298 the basic 40 test point module from coil, full scale movements and mirror Ancom is discussed in a leaflet. scales manufactured by British Physical General Electronics Circuits by JJ de- Geometrical Theory of diffraction and Ancom, Cheltenham, Glos. 303 Laboratories, Radlett, Herts. 283 France, £12, is intended as a first its applications, is the first volume in the course on electronic circuitry aimed IEE electromagnetic waves series cover- Industrial digital transducers are at the level of the engineering tech- ing both theory and application of Enquiry Service discussed in a catalogue from Orbit nician. Holt Sanders Ltd, Eastbourne, gdt. Peter Peregrinus, Stevenage, For rapid access to further Controls which also includes technical Sussex. 290 Herts. 297 information on the three broad ranges information, use the reply of transducers the company has An eight page application note from The volume of the proceedings of the paid card at the end of available. Orbit Controls, Cheltenham, Hewlett Packard describes the design LOA symposium held in Copenhagen is the commercial section. Glos. 284 and construction of a single stage entitled "The accuracy of flow measure- Our R.E.S. department bipolar amplifier at 4 GHz with a ments by Laser Doppler methods" and provides same day turn- Static power frequency changers, noise figure of 2,6 dB and an associated comprises 736 pages. Its 62 papers are £20, describes the basic operating gain of 10,8 dB. Hewlett-Packard, related to subjects such as Doppler round on all enquiries. principles of ac changers and presents Wokingham, Berks. 291 signals, and signal processing. Pro- 109 on enquiry card

EEV makes a vidicon.

If you use closed circuit TV, you And special rugged types need EEV vidicons. are made to withstand shock Our tubes ensure reliable round- or vibration. the-clock operation, and cover all EEV makes the dependable, TV pick-up applications. high quality vidicons you need. In mono or colour. For most At attractive prices. For quick cameras. In electrostatically delivery now. focused and magnetically Contact your local EEV agent or focused types (separate or write for data and prices to integral mesh). With a Camera Tube Sales at Chelmsford, range of photosurfaces. England.

EEVand M-0V know how Members of GEC-turnover £1902 million

ENGLISH ELECTRIC VALVE CO LTD, Chelmsford, Essex, England CM12QU. Tel: 0245 61777. Telex: 99103. Grams: Enelectico Chelmsford. SC En

Electronic Engineering December 1976 121 Z.411111.111111,- '7p:1'We er.-1fflereverem",• -

SEMICONDUCTORS

ENQUIRY No. 175

MONOLITHIC CERAMIC CAPACITORS

RFI Environmental Gaskets Conductive Elastomeric Sheets Conductive Compounds Conductive Heat Shrinkable Shielding Moulded, Glass Encased Thermally Inductive Insulation Resin Coated Chips Keyboards ENQUIRY No. 177

FIXED & VARIABLE Please circle the relevant enquiry RESISTORS numbers for further information on these products. The Steatite Group of Companies Hagley House Hagley Road Birmingham B16 8QW Tel: 021 454 6961

Solid Carbon Carbon Film Metal Oxide Film Metal Film, Cermet Precision Wirewound ENQUIRY No. 179

122 Electronic Engineering December 1976 "-je- 104 on enquiry card 111 on enquiry card Association of Please, note on your diary.. Certified Accountants Incorporated by Royal Charter finance and accounting diploma for engineers and • managers Ten-month part-time courses

As a specialist or manager you need an understanding of financial management and planning management accounting and an insight Into taxation.

Acquire this expertise by studying for the Certified Diploma In Accounting and Finance (designa- tory letters CDipAF), a qualification specially designed for non-accountants awarded by the Association of Certified Accountants.

Many professional people have already received the Diploma Scheme with enthusiasm and it has been described by a Chartered Engineering Institution as '. . . invaluable for planning, controlling and measuring business in financial terms . . .

START NOW to study by the Association's own successful com- posite course based on correspon- dence study supplemented with five days of full-time personalised tuition.

To: The Secretary, 4 sections: Components -Measurement Certified Diploma Scheme (EMG1) Association of Certified Raw Materials & Products -Equipement & Methods Accountants, an ever increasing number of visitors: 9 Museum House, Museum Street, London WC1A 1JT (01-590 7179) 1974 -57.000 1975 -61.000 permanent entrance cards Please send me details of the 1976 -72.000 Certified Diploma Scheme

Name You must come to Paris again this year! Address

Further particulars FRENCH TRADE EXHIBITIONS and free entrance 196 Sloane Street LONDON S.W. 1 cards on request: e 235.32.34 -235.32.35 n91 91 32 Francom Londres

Electronic Engineering December 1976 123. 117."("7-1- " 'le ••-•"-- -y ,e.-.y-mt-trtgeterm""e,,•„ • „ 711,1;4411141110 . 112 on enquiry card 113 on enquiry card e Q Does anyone know of agood engineering reference book? By order of A Yes. Kempe's Engineers Year Book. Thorn Consumer Electronics, Ltd. Q What's in it? A Everything you need to know about engineering. LIGHT ELECTRONICS Q Who's the author? A It has aselect team of FACTORY 6L OFFICES contributors. All specialists in their chosen subjects. Q Is it anew book? 31,300 sq. ft. A -No. The 1976 edition is new. But it is the 82nd edition. Engineers haNre been using it for generations. Q Doesn't that make it abit old SOUTHEND -ON -SEA fashioned? A Absolutely not. Every year the complete text is read, checked and TO LET or FOR SALE updated. A Isuppose it's terribly expensive? A No. £14.50 for atwo volume set in a Existing semi-skilled mainly female presentation case. labour force of about 350 could be Q It sounds exactly what I'm available. looking for. Where can Iget a copy? A From your local bookseller or direct from the publisher at the address below.

Chamberlain Kempe's Engineers Year Book &Willows 30 Calderwood Street Estate Agents •Surveyors •Valuers Woolwich, SE18 6QH 23 MOORGATE LONDON EC2R 6AX 01-638 8001

114 on enquiry card 115 on enquiry card LIQUID CRYSTAL ANTI STATIC PROBLEMS? DISPLAYS lIuiuIuIuuuI 111

1,3 IL7 P4 •e R" IC] i D C3 17) Cf /

Ili ... - III

Electrovac LCD's -field effect, multicolour are available in production quantities, feature long life for avariety of consumer and professional applications. Full catalogue ANTI STATIC Er CONDUCTIVE PLASTIC PRODUCTS available from:- PLUS DESTATICIZING BLOWER FROM WESTCORP. JOSEPH ELECTRONICS LTD., AVAILABLE FOR USE IN ELECTRONIC, ORDNANCE, Westminster House, MEDICAL Et ALL APPLICATIONS WHERE STATIC ELECTRICITY IS A PROBLEM. Stratford Road, Shirley, TELEPHONE: Solihull, BILLINGHURST (040 381) 3633 West Midlands B90 3AQ NIMROD ELECTRONICS LTD. NIMROD HOUSE, BILLINGSHURST, Tel :021 745 3251-2-3 WEST SUSSEX RH14 9GX ENGLAND Telex: 339325 ,

124 Electronic Engineering December 1976 116 on enquiry card THE COMPLETE TEST FACILITY

Solving test problems requires modern, regularly calibrated test equipment and skilled staff. We sell both in one package. Our equipment, technicians, approved facilities and procedures are all yours when you use our services. We collect your untested P.C.B.'s, test, repair and return them to you complete with test record and guarantee. It's the complete solution to your testing problems. Our customers include many well known companies — and they know that our services save them money and cure their testing headaches all in one go. So don't play expensive games with A.T.E. — spend afew pence to telephone us instead.

You've n-othing to lose but your problems!

I I APPLIED DIGITAL DEVICES LTD. 36 Tewin Road, Welwyn Garden City, Herts AL7 1AH

Mal Telephone: Welwyn Garden 33491

117 on enquiry card The Daturr corner post: it's as long and strong as you want

(with apologies to Guinness)

Look at that section of the Daturr rack corner post—there's none stronger. As one customer said "We can rack our brains but we can't brain your racks". Made in 7 standard heights, from 14U to 44U, and 4 standard depths, the Daturr steel rack takes some beating. As well as the welded version there's a knock-down type too.

For lighter applications try the new all-aluminium rack. It's made in 35 sizes. Daturr Limited, Market Road, Richmond, Surrey, TW9 4NE Telephone 01-876 0589/6244 Telex 929949

125 rysertigem--"r "r' 5'

CLASSIFIED 01 -ggief777

STRIPPER FOR HIRE I CAPACITY APPOINTMENTS PRINTED CIRCUITS IN THE MIDLANDS Your free issue wire cut and stripped from 75p per 1,000 SUB-CONTRACT CAPACITY We have capacity for the manu- leads, tinning facility also available. ENGINEERS facture of Printed Circuit Our modern facilities are Boards, single or double sided. available under qualified en- Hard Gold Plate and machined Printed circuits assembled. gineering management for:— WANTED: to any shape required. We Cable looms and complete P.C.B Assembly specialise in giving Good Fast equipment manufactured to Service for Short Runs. One — Electro -Mechanical order. Wire supplied and cut, Assembly CE, ME, AND EE with off Prototype Service from receipt of 2X Artwork. Glass a quotation will cost you — Cableforms Fibre only. No through hole nothing from:— — Sheet metal and Press Ph.D or MS Arabic plating, please. Work Hamer fr Emmins Ltd., -- Coil-Winding language required. Write DIKTRON DEVELOPMENTS LTD. Deseronto Wharf, St. Mary's Production Engineering Er 5 Highgate Square, Road, Langley, Bucks. Electricals (Southern) Ltd., to Royal Scientific So- Birmingham 1112 ODR Tel: Slough 75-46760 or Baden Street, Chard, Telephone: 021-440 1321-2 46769. Somerset TA20 2AH ciety P.O. Box 6945. Tel: Chard (046-06) 4211 Amman — Jordan. CAPACITY AVAILABLE For electronic wiring, P.C.B. assembly, (Batch-work Et Proto- type) Test and light engineering WANTED BUSINESS OPPORTUNITIES if required. ERKCI SWIFT AND ACCURATE SERVICE, ROTARY SCREENING USING ONLY EXPERIENCED limited MACHINE WANTED RECORDED PERSONNEL, ANNOUNCEMENTS SUPERVISED BY SENIOR Second-hand rotary screening GRADE TECHNICIANS machine for CRT manufacture, Advertiser wishes to contact SUBCONTRACTORS TO THE firm Interested In preferred size 12 or 18 head Contact:— ELECTRONIC INDUSTRY commercialisation of recorded but larger machine would be announcements idea. Appleton Audio Services Ltd., considered for modification. Applications to process control, Electronic Engineers, Capacity available for com- State price required together 66 Silvester Road, lifts, crowd control, security, prehensive production service with condition and whether etc. London 5E22. Tel: 01-693 5051. under qualified engineering dismantled or stored. Box No. 1304. Box No. EE 1305 4,V1/1/401/1,A.A.41/1"N/LOWIL/4"‘ management.

For enquiries relating to PCB ELECTROCIRCUITS (P.C.) LTD., assemblies; cable forms: panel SERVICES DELAMARE ROAD, and switch wiring; testing; CHESHUNT, sheet metal work, contact: HERTS. EN8 9UB ERKO LTD. SYSTEM ENGINEERING Manufacturers of P.C.B's Thameside Industrial Estate, ELECTRICAL, ELECTRONIC AND MECHANICAL Thro' hole plated Silvertown, London E16. HAVE YOU A PROBLEM? Conventional, Tel: 01-511 0877 or • Interfacing Equipment • Equipment requiring production engineering gold plating, 01-511 0725 • Prototype manufacture • Specialized test rigs All or part service We have a group of highly trained Electronic and Mechanical Tel: Waltham Cross 38600 Design and Production Engineers. or 20344, for leaflet or MAIN CONTRACTORS TO M.O.D. ask for quotation. A.P.T. RADAR SYSTEMS LIMITED, Chertsey Road, Byfleet, Surrey.. LAMPS Tel: BYFLEET 41131 Telex 262525 SWITCH, Member of E.M.C. Group of Companies TELEPHONE, MICRO. ed- ARTWORK" MIDGET. AND SMALL INDICATORS. EMI s. PCBs COMPONENT SERVICE TO TRADE SERVICES LTD., PUBLICITY AND from Specialist Manufacturer AND INDUSTRY South st., Hertford, Mal 1off or 10,000 Herts. Nameplates, control panels, TECHNICAL PRINTING =lb Tel: Hertford 57766 Labels, badges of all descrip- LORMAY LT ID tions, in all materials. Cast in ./M Wappenhaam Blokesley Circle 120 on enquiry card metal, injection moulded in for the Electronics Industry Towceeter C032-7323 polystyrene, silk screen printed Northants 209 on aluminium (and other Design, Single and materials), hot-blocking, en- graving. Mufti-colour Printing Circle 121 on enquiry card Also industrial gift and trade Write or 'phone: promotions. Gift items avail- Stan Peddle, MD FOR SALE able including decimalisation DESIGN & DEVELOPMENT conversion tables. Literature on CREATIVE PRESS (Reading) request. LTD., Competent engineering effort available for all aspects and I. Markovits Ltd., 42 Portman Road, ENAMELLED COPPER WIRE Reading, Berks. levels of electronic design. 1/2/3 Cobbold Mews, W.12. swg 1 lb 4oz 20e Tel.: 01-743 1131/2 1313 Tel: 0734 55388 Single circuits or complete 14-19 2.40 .69 .50 20-29 2.45 .82 .59 systems to production stage. 30-34 2.60 .89 .64 • 35-40 2.85 1.04 .75 INTEK ELECTRONICS LTD. inclusive of p&p and V4T PLEASE RING 01-855 7777 EXT. 2016 4 Lowfield Lane, SAE brings Catalogue of copper Et Hoddesdon, Herts. resistance wires in all coverings TO PLACE YOUR ADVERTISEMENTS THE SCIENTIFIC WIRE COMPANY Tel. Hoddesdon 62053 PO Box 30, London E4 9BW 6243

126 Electronic Engineering December 1976 ter'.eA.r

APPOINTMENTS

Engineers and Programmers acareer in Microcomputers with CAPAlicroSoft

eCAP Group, CAP Engineers These posts will be based MicroSoft's parent, was established initially in our Reading office and A number of vacancies exist for in 1962 and has auniquely successful there will be some opportunity for engineers with at least 2 years' travel. In any new operation such as record of growth to its current industrial experience to work on CAP MicroSoft, the willingness to be position of the UK's largest microcomputer systems. It is flexible as the company develops will independent software house. The expected that applicants will be be looked for but the well developed main group activities have been the currently designing systems using career plan mechanisms applicable MSI/LSI Logic or alternatively implementation of systems for throughout the CAP Group will working in the minicomputer computer users ranging from large apply and all opportunity for interfacing area. Applicants should on-line financial systems to advanced promotion will be given. have done some programming, technology projects in such fields as although not necessarily of All staff get 4weeks holiday and avionics and process control. The microcomputers. other benefits include staff mortgage group employs over soo professional service, group health insurance and a Graduate Membership of an staff at present. two-tier pension scheme. Senior staff appropriate institute is desirable. may be offered CAP shares in this CAP Micro Soft was formed Salary to £5,000 staff-owned Group. earlier this year to extend our services into the microprocessor field. If you would like to apply, write to the address below quoting the CAP was the first group in the Programmers relevant reference. (EE. 1'16) country to take this step and is now A number of vacancies are also expanding further to meet present available for programmers with two A.V.W. Knott, demands. Areas of work include a or more years' experience to work on Assistant Personnel Manager, Computer Analysts and Programmers Ltd., variety of client projects from microcomputer projects. CAP House, 14-15 Gt. James Street, feasibility studies to system It is expected that applicants will London WCIN 3DY. implementations, development of be currently working with software and hardware components minicomputer systems, probably in the system software area. Some for development systems, and data interest or background in electronics communication networks for would be an asset although the prime CAPBritain's largest distributed processing applications. requirement is an interest in independent software house microcomputers. Salary to £4,150 London, Reading, Manchester and Overseas}

THE UNIVERSITY OF LANCASTER

Substantial Japanese instrument company requires DEPARTMENT OF ENVIRONMENT SCIENCES EXPERIMENTAL OFFICER IN ELECTRONICS sub-agents to franchised U.K. distributor in all The successful candidate will undertake the design, construc- European countries with OEM and/or direct market- tion and operation of electronic equipment of a geophysical nature and be responsible to Dr. McIlyeen. This is a 2-year ing experience preferably covering panel meters, appointment.

instruments and amateur radio equipment. Salary scale £2,776 - £4,602 (under review).

Further particulars may be obtained, quoting reference L58/A BOX No. EE 1307. from the Establishment Officer, University House, Lancaster LA1 4YW to whom applications (5 copies) naming three referees should be sent not later than 5 January 1977.

YOU CAN REACH OVER 100,000 READERS WITH AN ADVERTISEMENT ON THESE PAGES

Electronic Engineering December 1976 127 7r,1 v-,TP - `1730.7 _ 'We" ''''retre7-43true,;I:e-v2"'‘e ,•- 118 on enquiry card 119 on enquiry card ZENITH SILVER SAVINGS? Electro -conductive silvered MAINS VOLTAGE plain and hollow glass beads STABILISERS

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VS 9/75

INDEX TO ADVERTISERS

Allen Bradley Electronics Ltd 3 Harwin Engineering Ltd .. 64 Plessey Windings Ltd .. 8 Alma Components Ltd .. 6 Hellermann Electric Ltd .. 92 Pye Connectors Ltd .. 98 Amphenol (UK) Ltd.. 100 lefellermann Insuloid Ltd .. .. 32C Pye TMC Components Ltd.. 117 Ancom Ltd .. • 70 Hengstler (GB) Ltd .. .. 32 Pulse Engineering Ltd .. 64 Applied Digital Devices Ltd 125 Hewlett Packard Ltd.. .. OBC, 76 • RIFA .. .• 22 Association of Certified Accountants • 123 Highland Electronics Ltd .. .. 97 Radiatron Components Ltd 92 Astralux Dynamics Ltd .. •• 94/95 Hollingsworth Terminals Ltd .. 114 Rosemount Engineering Ltd .. 32D Auget Ltd .. 101 Honeywell Ltd .. 90 Roxburgh Electronics Ltd .. .. 86 Aviation Electrical Et Radio Co Ltd 86 Houseman Hegro Ltd .. .. 101 Aviquipo (Great Britain) Ltd .. 102 Hunting Hivolt Ltd .. 80 SDSA .. 123 SE Labs (EMI) Ltd .. 9, 23 Barr and Stroud Ltd .. .. 10 ITT Components Ltd 15, 18 Sanwa Electric Instrument Ltd .. *119 Bauch, FW 0 Ltd .. . 102 ITT Instrument Services Ltd 24 Sasco Ltd .. . 20 BICC-Burndy Ltd .. 'I 04/105 Imhof Bedco Ltd .. 18 Smiths Industries Ltd 106/107 Bryans Southern Instruments Ltd.. 10 Industrial Instruments Ltd .. 115 Solartron Ltd .. .. 38. Bulgin, A F Er Co Ltd .. 86 Intel Group Ltd 109 Souriau (UK) Ltd .. • 88 Burr Brown Research Group 12 International Rectifier Ltd .. 63 Sovitec, SA .. 128 Invader Components Ltd .. 114 Spectra -Tek (UK) Ltd .. 22 Cetronic Ltd .. 70 124 Sprague Electric (UK) Ltd .. 83 Chamberlain Er Willows Ltd 124 Joseph Electronics Ltd .. •• Steatite Insulations Ltd .. 122 CoMark Electronics Ltd Insert Kenure Developments Ltd .. 84 Cosmocord Ltd .. 116 Technical Tapes Ltd .. 12 Lane, F C Ltd .. .. Insert Teledyne Semiconductors Ltd .. 48 Dana Electronics Ltd 57 Lemo Ltd .. .. 93 Teledyne Philbrick Ltd .. 78 Data Precision Ltd .. 32B Linstead Manufacturing Co Ltd .. 114 Telford Development Corporation 58 Datron Electronics Ltd • 33 Littelfuse (GB) Ltd .. .. 78 Teradyne Ltd .. 80 Daturr Ltd .. • 125 Lyons, Claude Ltd .. .. 32D Texas Instruments Ltd .. 35 Devices Instruments Ltd 82 Lyons, Instruments Ltd .. .. 111 Thomas 8. Betts Ltd .. IFC Dow Chemicals Ltd .. 81 McMurdo Ltd •• 40 Thomson, CS F Ltd...... 11 ENI Power Systems Ltd ., 72 3M (UK) Ltd .. • 32A Tranchant Electronics (UK) Ltd .. 82, 119 Electro Match Ltd .. .. 84 ML Components Ltd •• 96 Ultra Electronic Components Ltd .. .. 39 Memec Ltd .. Insert Electroplan Ltd .. 52 • Varelco Ltd .. IBC Metway Ltd .. 85 English Electric Valve Co Ltd 120/121 • Vero Electronics Ltd .. •.: 85 Molex Ltd .. 110 Erma Ltd .. .. 32B •• Viking Industrial Ltd .. 108 Mullard Ltd .. 50/51 Exel Electronics Ltd .. .. 14 •• Vision Engineering Ltd 90 Ferranti Ltd .. 112/113 Nimrod Electronics Ltd 124 Vitality Ltd .. 70 French Trade Exhibitions .. .. 123 Optima Enclosures Ltd 118 Wavetek Ltd .. .. 16 Fylde Electronic Products Ltd .. 14 Oxley Developments Ltd 116 Waycom Ltd .. .. 46, 66 Westinghouse Brake Et Signal Ltd .. 37 GEC Semiconductors Ltd .. 68 Panduit Ltd .. 84 Wilmot Breeden Electronics Ltd .. .. 2, 36 General Instruments Ltd .. 28 Pell, Oliver Ltd 30 Wingrove Er Rogers Ltd .. .. 99 Gould Advance Ltd .. .. 34, 71 Plessey Connectors Ltd 87 Gresham Lion Ltd .., .. 56 Plessey Microsystems Ltd 13 Zenith Electronic Co Ltd .. .. 128

Printed heatset web-offset, in Great Britain by Eden Fisher . (Southend) Suttop Southe_rd-on .-_Sea,..Es.sex, for the proprietors Morgan-Grampian 2 on enquiry card our modular connector enables you to make only the contacts you want to accept.

Varelco's Series 6072 Modular Connector is lengths there are supplementary mounting flanges the one with all the options. Look at the variations in plastic or metal, and the metal version provides available to suit your specification. Upto 89 contacts an open card slot feature. Or you can choose an in asingle row or 178 in the dual configuration. extended card guide with integral lug. So, when you state the number of contacts, you •That's the Series 6072, another cost-effective determine the length of moulding. You want connectdr from Varelco; the modular connector polarisatibn? No problem. Achoice of two keying with all the options to enable you to make only the inserts, one uses the contact position, the other, contacts you really need. the between-contact position, so no loss of contacts. "GREAT CONNECTIONS... WORLDWIDE" Terminations? You have achoice of mini wire-wrap posts, solder eye or PC. terminals. Varelco Limited And, in accordance with the accepted high Exning Road Newmarket Suffolk England CB8 OBB standards of Varelco, contacts are of phosphor Tel: Newmarket 4516 Telex: 81519 bronze, gold plated in nickel. Contact rating — 3amperes, contact resistance —10 milli-ohms. Which only leaves the mounting and, again, Varelco the choice is yours. Full lengths are available with integrally moulded plastic lugs, but for shorter 1---7 Limited Hewlett-Packard's super-bright LEDs, For immediate delivery please contact using the latest transparent substrates our distributors. and nitrogen doping technology (TSN), Celdis Ltd., 37-39 Loverock Rd., Reading, are up to 5times brighter than those Berks RG3 lED.4Tel: Reading 582211. using conventional GaAsP on GDS Sales Ltd., Michaelmas House, GaAs and come in four colours Salt Hill, Bath Road, Slóugh, Berks SL13 3UZ. with dominant wavelengths •Tel: Slough 31222. (AD) of approximately acro Marketing Ltd., 640 nm (deep red), 625 nm 96 Bath Road, Slough, Berks. (orange-red), 585 nm Tel: Burnham 63011. (amber-yellow), and 570 nm Or, for further information, (green). write to us direct. With this new technology HP can offer an unexcelled range .f LE lamps: T-Is and T-1 34s, normal and low- dome, miniature and arrays, rectangular5, IC-LEDs, R-LEDs, hermetic (JAN, Sales and service from 172 offices in 65 countries. JANTX), narrow beam', clear, diffuse, etc. Winnersh, Wokingham, Berks. RG1 5AR. Tel: Wokingham 74774.