The following list of manufacturers and suppliers is intended as a guide for the reader and gives some companies who produce items under the headings given. It is not intended to be a comprehensive listing of any one product.

COMPONENTS Capacitors Advance Filmcap Ltd Bosch Ltd Britimpex Ltd A F Bulgin & Co Ltd Cambion Electronic Products Ltd Daly (Condensers) Ltd Dubilier Condenser Co (1925) Ltd Electrautom Ltd Electroustic Ltd Electrosil Ltd Emihus Microcomponents Ltd English Electric Valve Co Ltd ERG Industrial Corporation Ltd Erie Electronics Ltd G E Electronics (London) Ltd Guest International Ltd Hawnt & Co Ltd A H Hunt (Capacitors) Ltd IRC Components Ltd ITT Components Group (Capacitor Division) Impectron Ltd London Electrical Manufacturing Co Ltd Macro-Marketing Ltd Matthey Printed Products Ltd Mullard Ltd Oxley Developments Company Ltd Pedoka Ltd The Plessey Co Ltd (Components Group) RS Components Ltd RIC Capacitors Ltd Salford Electrical Instruments Ltd Siemens (United Kingdom) Ltd Sprague Electric (UK) Ltd Techmation Ltd

Product Guide

Telephone Manufacturing Co Ltd Townsend-Coates Ltd Union Carbide UK Ltd Vitramon Europe Waycom Ltd Wego Condenser Co Ltd

Resistors and Potentiometers A B Electronic Components Ltd Alma Components Ltd B & K Instruments Ltd A F Bulgin & Co Ltd C G S Resistance Co Ltd Colvern Ltd Cressall Manufacturing Co Ltd Davies Integrated Sales Dubilier Condenser Co (1925) Ltd Electrautom Ltd Electroustic Ltd Electrosil Ltd Erie Electronics Ltd G E Electronics Ltd Holsworthy Electronics Ltd ITT Components Group Europe ITT Components Group Europe (Potentiometer

Division) Impectron Ltd Lindair Optronics (Industrial) Ltd Litton Precision Products May Precision Components Ltd Morganite Resistors Ltd Mullard Ltd Pedoka Ltd Penny & Giles Ltd The Plessey Co Ltd (Components Group) Power Development Ltd RS Components Ltd Reliance Controls Ltd Salford Electrical Instruments Ltd Sprague Electric (UK) Ltd Walmore Electronics Ltd Waycom Ltd Welwyn Electric Ltd

185

Coils & Transformers Abrex Electronics Ltd Aladdin Components Amphenol Ltd Astralux Dynamics Ltd Ataka & Co (UK) Ltd Avel Products Ltd Bede Transformer Co Ltd A F Bulgin & Co Ltd Cambion Electronic Products Ltd Clarke & Smith Manufacturing Co Ltd Drake transformers Ltd Dynamo & Electrical Services Ltd ERG Industrial Corporation Ltd Elden Electronics Ltd Electro-Voice Products Ferranti Ltd Foster Transformers Ltd Gardners Transformers Ltd Gresham Transformers Ltd Hinchley Engineering Co Ltd Howells Radio Ltd ITT Components Group Europe ITT Components Group Europe

(Rectifier Product Division) Lambda Electronics Litton Precision Products Mullard Ltd Parmeko Ltd Pedoka Ltd The Plessey Co Ltd (Components Group) Roberts Electronics Ltd Salford Electrical Instruments Ltd Southern Transformer Products Ltd Walmore Electronics Ltd Whiteley Electrical Radio Co Ltd Zenith Electric Co Ltd

Relays Allen West (Brighton) Ltd Alma Components Ltd Arrow Electric Switches Ltd Associated Automation Ltd Astralux Dynamics Ltd B & R Relays Ltd Brookhurst Igranic Ltd Clare (C P) Electronics Ltd Clifford & Snell Ltd Cox Engineering Company Ltd Jack Davis (Relays) Ltd Diamond H Controls Ltd Engel & Gibbs Ltd ERG Industrial CorporatiQn Ltd F R Electronics

(A Division of Flight Refuelling) Hendrey Relays Ltd Impex Electrical Ltd ITT Components Group Europe

186

Keyswitch Relays Ltd Londex Ltd Macro-Marketing Ltd Magnetic Devices Ltd The Marconi Co Ltd G A Stanley Palmer Ltd Parmeko Ltd Pedoka Ltd Oliver Pell Control Ltd The Plessey Co Ltd (Components Group) Simmonds & Robinson Ltd SquareD Ltd Techna (Sales) Ltd Telerelay (Sales) Ltd Thorn Bendix Ltd

(Electrical Components Division) The Valiant Engineering Co Walmore Electronics Ltd Westinghouse Brake & Signal Co Ltd

Printed Circuit Boards ABC Electronics (Oldham) Ltd A B Electronic Components Ltd Bribond Printed Circuits Ltd Circaprint Ltd Cressall Printed Circuits Ltd Davall (S) & Sons Ltd Exacta Circuits Ltd K & N Electronics Ltd Litton Precision Products M B Metals Ltd MEL Equipment Co Ltd Mills & Rockleys (Electronics) Ltd Mullard Ltd Technograph & Telegraph Ltd

Thermionic Valves & Tubes Aero Electronics Ltd Ataka & Co (UK) Ltd Britimpex Ltd Chelmer Valve Co Claude Lyons Cole Electronics Ltd Dale Electronics Ltd EMI-Varian Ltd English Electric Valve Co Ltd Ferranti Ltd Hivac Ltd ITT Components Group Europe Litton Precision Products The M-0 Valve Co Ltd Mullard Ltd Rank Electronic Tubes RCA Ltd (Electric Components Division) Siemens (United Kingdom) Ltd Thorn Radio Valves & Tubes Ltd Twentieth Century Electronics Ltd Walmore Electronics Ltd

Semiconductors Aero Electronics Ltd Britimpex Ltd Cole Electronics Ltd Dale Electronics Ltd Duval Emihus Microcomponents Ltd Fairchild Semiconductor Ltd Farnell Electronic Components Ltd Ferranti Ltd Hird-Brown Ltd ITT Components Group Europe

(Valve Product Division) Jermyn Industries Lindair Optronics (Industrial) Ltd Macro-Marketing Ltd Marconi-Elliott Microelectronics Ltd Mullard Ltd The Plessey Co Ltd (Components Group) RCA Ltd (Electric Components Division) SDS (Portsmouth) Ltd SGS (United Kingdom) Ltd STC Semiconductors Ltd Texas Instruments Ltd Walmore Electronics Ltd Westinghouse Brake & Signal Co Ltd

Connectors A B Electronic Components Ltd AMP of Great Britain Ltd Amphenol Ltd Aviation Electrical & Radio Ltd Belling & Lee Ltd British Insulated Callender's Cables Ltd DTV Group Ltd Dale Electronics Ltd Duval Electrautom Ltd Emihus Microcomponents Ltd Farnell Electronic Components Ltd Ferranti Ltd Greenpar Engineering Ltd Guest International Ltd ITT Electronic Services Intel Connectors Ltd Klippon Electricals Ltd Lemosa Ltd MB Metals Ltd Macro-Marketing Ltd Metway Electrical Industries Ltd The Plessey Co Ltd (Components Group) Racal Electronics Ltd Radial! Microwave Components Ltd SDS (Portsmouth) Ltd Townsend-Coates Ltd Walmore Electronics Ltd

INSTRUMENTS

Ammeters Anders Electronics Ltd Aveley Electric Ltd Avo Ltd Cole Electronics Ltd Comark Electronics Ltd Graham & White Instruments Hawnt & Co Ltd Hewlett-Packard Ltd Kandem Electrical Ltd Keithley Instruments Ltd Levell Electronics Ltd Record Electrical Co Ltd (The) Salford Electrical Instruments Ltd Sangamo Weston Ltd Sifam Electrical Instrument Co Ltd Sullivan H W Ltd Tinsley H & Co Ltd Turner (Ernest) Electrical Instruments Ltd White Electrical Instrument Co Ltd

Analysers A E P-International Ltd AIM Associates Cambridge Ltd B & K Laboratories Ltd Dale Electtpnics Ltd Davian (Instruments) Ltd Fenlow Electronics Ltd General Radio Co (UK) Ltd Hewlett-Packard Ltd ITT Electronics Services Marconi Instruments Ltd Omega Laboratories Ltd Racal Electronics Ltd Servomex Controls Ltd Tektronix UK Ltd

Bridges Automatic Systems Laboratories Ltd Aveley Electric Ltd Avo Ltd (Avo International Division) B & K Laboratories Ltd Cambridge Industrial Instruments Ltd Dale Electronics Ltd Dawe Instruments Ltd General Radio Co (UK) Ltd Hewlett-Packard Ltd Kandem Electrical Ltd Leeds & Northrup Ltd Marconi Instruments Ltd Time Electronics Ltd Tinsley H & Co Ltd Sullivan H W Ltd

187

Comparators AIM Electronics Ltd British Physical Laboratories Croydon Precision Instrument Co Darang Electronics Ltd Elcometer Instruments Ltd Electrographic Ltd General Radio Co (UK) Ltd Hewlett-Packard Ltd Lyons Instruments Ltd Racal Electronics Ltd Salford Electrical Instruments Ltd Wareham (EM) (Measuring Systems) Ltd

Detectors Automatic Systems Laboratories Ltd Aveley Electric Ltd Avo Ltd (Avo International Division) Brookdeal Electronics Ltd Cole Electronics Ltd Croydon Precision Instrument Co Dawe Instruments Ltd General Radio Co (UK) Ltd Hewlett-Packard Ltd Keithley Instruments Ltd Leeds & Northrup Ltd Levell Electronics Ltd Lyons Instruments Ltd Roberts Electronics Ltd Trio Instruments Ltd Turner (Ernest) Electrical Instruments Ltd

Fluxmeters Ancillary Developments Ltd C D C (Great Britain) Ltd Cole Electronics Ltd Control Technology Ltd Elliott Space & Weapon Automation Ltd

(Space & Guided Weapons Division) Sonatest Group of Companies The Varian Associates Ltd

Galvanometers Avo Ltd (Avo International Division) Cambridge Industrial Instruments Ltd Comark Electronics Fluke International Corporation Gallenkamp (A) & Co Ltd Gulton Industries (Britain) Ltd

(West Instrument Division) Hewlett-Packard Ltd Honeywell Ltd Leeds & Northrup Ltd Racal Electronics Ltd Salford Electrical Instruments Ltd Sifam Electrical Instrument Co Ltd Turner (Ernest) Electrical Instruments Ltd White Electrical Instrument Co Ltd

188

Signal Generators AIL (Division of Cutler-Hammer) AIM Electronics Ltd AIM Associates Cambridge Ltd Aveley Electric Ltd Avo Ltd Britec Ltd Dale Electronics Ltd Davian (Instruments) Ltd Davies Integrated Sales Dawe Instruments Ltd Farnell Instruments Ltd Feedback Ltd General Radio Co (UK) Ltd Hewlett-Packard Ltd Marconi Instruments Ltd Prosser Scientific Instruments Ltd Racal Electronics Ltd Roberts Electronics Ltd Solartron Electronic Group Ltd The Tektronix UK Ltd Texas Instruments Ltd Venner Electronics Ltd

Microammeters Anders Electronics Ltd Bach-Simpson Ltd Cole Electronics Ltd Comark Electronics Ltd Guest International Ltd Hewlett-Packard Ltd Kandem Electrical Ltd M L Industrial Products Ltd

(Electronics Division) Roberts Electronics Ltd Salford Electrical Instruments Ltd Sangamo Weston Ltd Sifam Electrical Instrument Co Ltd Turner (Ernest) Electrical Instruments Ltd Weir Electrical Instrument Co Ltd The

Milliammeters Anders Electronics Ltd Aveley Electric Ltd Cole Electronics Ltd Comark Electronics Ltd Ferranti Ltd Fieldtech Ltd Gallenkamp (A) & Co Ltd Hewlett-Packard Ltd M L Industrial Products Ltd

(Electronics Division) Roberts Electronics Ltd Salford Electrical Instrumeents Ltd Sangamo Weston Ltd Sifam Electrical Instrument Co Ltd Weir Electrical Instrument Co Ltd The

Millivoltmeters A E P International Ltd Aveley Electric Ltd Avo Ltd (Avo International Division) Cambridge Industrial Instruments Ltd Cole Electronics Ltd Davian (Instruments) Ltd Ferranti Ltd Gallenkamp (A) & Co Ltd Guest International Ltd Hewlett-Packard Ltd Honeywell Ltd ITT Electronic Services Marconi Instruments Ltd Racal Electronics Ltd Roberts Electronics Ltd Salford Electrical Instruments Ltd Sangamo Weston Ltd

Bowmar Instrument Ltd Cole Electronics Ltd Dana Electronics Ltd Dynamco Ltd Farnell Instruments Ltd General Radio Co (UK) Ltd Hewlett-Packard Ltd ITT Electronic Services Marconi Instruments Ltd Siemens (United Kingdom) Ltd Solartron Electronic Group Ltd The Walmore Electronics Ltd Weir Electronics Ltd

Wattmeters Anders Electronics Ltd Aveley Electric Ltd

Sifam Electrical Instrument Co Ltd Turner (Ernest) Electrical Instruments Ltd

Avo Ltd (Avo International Division) Bird Electronic Ltd

Oscilloscopes Avo Ltd (Avo International Division) CDC (Great Britain) Ltd Cossor Electronics Ltd Dynamco Ltd Hewlett-Packard Ltd Marconi Instruments Ltd Solartron Electronic Group Ltd The Tektronix UK Ltd Telequipment Ltd

Transistor Test Sets Avo Ltd Britec Ltd General Micronetics Ltd Hewlett-Packard Ltd Labgear Ltd Teradyne UK Ltd

Digital Voltmeters A E P International Ltd Bach-Simpson Ltd Britec Ltd

ADDRESSES

ABC Electronics (Oldham) Ltd 83 Lees Road Oldham Lancashire 061 624 8812

Cole Electronics Ltd Ferranti Ltd Hewlett-Packard Ltd Kandem Electrical Ltd Marconi Instruments Ltd Racal Electronics Ltd Salford Electrical Instruments Ltd Sangamo Weston Ltd

Frequency Counters A G Brown Electronics Ltd Aveley Electric Ltd Avo Ltd Britec Ltd Darang Electronics Ltd Dawe Instruments Ltd Farnell Instruments Ltd Graham & White Instruments Helga Electronics Ltd Hewlett-Packard Ltd ITT Components Group Europe Marconi Instruments Ltd Plessey Co Ltd The (Electronics Group) Racal Electronics Ltd Technitron Ltd Venner Electronics Ltd

A B Electronic Components Ltd Abercynon

A E P International Ltd 14 High Street

Glamorganshire Staines Abercynon (044374) 331 Middlesex

Staines 57571

189

AIL High House Bar line Beer Devon Seaton 325

AIM Electronics Ltd The River Mill St lves Huntingdonshire St lves 2901

AIM Associates Cambridge ltd The River Mill St lves Huntingdonshire St lves 2901

Abrex Electronics Ltd 6 Winchelsea Road Forest Gate London E 7 01 534 2409

Advance Filmcap ltd Rhosymedre Wrexham Denbighshire North Wales Ruabon (097 881) 2471

Aero Electronics Ltd Gatwick House Horley Surrey Horley (029 34) 5353

Aladdin Components Greenford Middlesex 01 578 2300

Allen West (Brighton) Ltd Mou lsecoombe Way Brighton BN2 40E Sussex Brighton (0273) 66666

AMP of Great Britain Ltd Terminal House Stanmore Middlesex 01 954 2356

Amphenol Ltd Thanet Way Whitstable Kent Whitstable (022 72) 4345

Anders Electronics ltd 48/56 Bayham Place Bayham Street London NW1 01 387 9092

190

Ancillary Developments Ltd Blackwater Station Estate Camberley Surrey Camberley 5385

Arrow Electrical Switches Ltd Brent Road Southall Middlesex 01 574 2442

Associated Automation ltd Dudden Hill Lane London NW10 01 459 8070

Astralux Dynamics ltd Brightlingsea Colchester Essex Brightlingsea (020630) 2517/8

Ataka & Co (UK) ltd Roman House Wood Street London EC2 01 638 8901

Automatic Systems Laboratories ltd Construction House Grovebury Road Leighton Buzzard Beds Leighton Buzzard 4624

Avel Products ltd 13-16Ayron Road South Ockendon Essex South Ockendon (700) 2263

Aveley Electric ltd Arisdale Avenue South Ockendon Essex South Ockendon 2263

Aviation Electrical & Radio ltd Moons Lane Horsham Sussex Horsham (0403) 60206

Avo Ltd Avocet House Dover Kent Dover 2626

B & K Instruments ltd 59 Union Steet London SE1 01 407 4567

B & K Laboratories Ltd Cross Lances Road Hounslow Middlesex 01 570 7774

B & R Relays Ltd Temple Fields Harlow Essex Harlow (027 96) 25231

Bach-Simpson ltd 331 Uxbridge Road R ickmansworth Herts Rickmansworth 76900

Bede Transformer Co ltd Bedesway Bede Trading Estate Jarrow Co Durham Jarrow (0632) 897281

Belling & Lee ltd Great Cambridge Road Enfield Middlesex 01 363 5393

Bird Electronic ltd 33a High Street Ruislip Middlesex Ruislip 74133

Bosch Ltd P 0 Box 166 Rhodes Way Watford WD2 4LB Herts Watford 44233

Bowmar Instrument Ltd 1 Ormond Avenue Hampton Middlesex 01 979 2349

Bribond Printed Circuits Ltd Terminus Road Chichester Sussex Chichester (0243) 84516

Britec ltd 17 Charing Cross Road London WC2 01 930 3070

Britimpex ltd 8-12 Rickett Street London SW6 01 385 0883 & 1007

British Insulated Callender's Cables Ltd Chelmer Valve Co Cressall Printed Circuits Ltd P 0 Box No 5 130 New London Road Reddicap Trading Estate 21 Bloomsbury Street Chelmsford Sutton Coldfield London WC1 Essex Warwickshire 01 637 1300 Chelmsford (0245) 55296 021 354 8048

British Physical Laboratories Circaprint Ltd Croydon Precision Instruments Co Radlett 17-21 Foster Street Hampton Road Herts Maid stone Croydon CR9 2RU 01 779 4844 Kent 01 684 4025 & 4094

Maidstone 55484 Brookdeal Electronics Ltd DTV Group Ltd Myron Place C P Clare Electronics Ltd 126 Hamilton Road London SE13 Stonefield Way West Norwood 01 852 7433 South Ruislip London SE27

Middlesex 01 670 6166 Brookdeal Electronics Ltd 01 8451288 Market Street Dale Electronics Ltd Brack nell Clarke & Smith Manufacturing Co Ltd 109 Jermyn Street Berks Melbourne Works London SW1 Bracknell 23931/5 Melbourne Road 01 930 0725

Wallington Daly (Condensers) Ltd Brookhirst lgranic Ltd Surrey

Elstow Road 01 669 4411 Granby Works Bedford Granby Industrial Estate Beds

Clifford & Snell Ltd Weymouth

Bedford (0234) 67433 Dorset 32 Carshalton Road Weymouth 2871

Brown (AG) Electronics Ltd Sutton

10-11 Royal Crescent Surrey Darang Electronics Ltd Glasgow C3 01 642 2255 RestmorWay 041 332 8671

Cole Electronics Ltd Hack bridge Surrey

A F Bulgin & Co Ltd Lansdowne Road 01 669 1140 By-Pass Road Croydon CR9 2HB

Barking Surrey Dana Electronics Ltd Essex

01 686 7581 Bilton Way

01 594 5588 Dallow Road Colvern Ltd Luton Spring Gardens Beds Romford Luton 24236 Essex

C D C (Great Britain) Ltd Romford 62222 S Davall & Sons Ltd Terminal House Wadsworth Road Grosvenor Gardens Comark Electronics Ltd Perivale London SW1 Brookside Avenue Greenford 01 730 8271 Rustington Middlesex

Sussex 01 998 1011 CGS Resistance Co Ltd Rustington 3147/8 Marsh Lane Jack Davies (Relays) Ltd Gosport Street Control Technology Ltd 9-1 0 Mallow Street Lymington 44 Meeching Road Old Street Hampshire New haven London EC1 Lymington (059 07) 3282 Sussex 01 253 3661

Newhaven 3535 Cambion Electronic Products Ltd Davies Integrated Sales Cambion Works Cossor Electronics Ltd 56 Queens Road Castleton The Pinnacles Basingstoke Nr Sheffield S30 2WR Harlow Hants Hope (Derbyshire) (043 32) 406 Essex Basingstoke 25220 & 4620

Harlow 26862 Cambridge Industrial Instruments Ltd Davian (Instruments) Ltd Sydney Road Cox Engineering Co Ltd 47 Rowelfield Muswell Hill 14 Park Lane Luton London N10 Sheffield S10 Beds 01 883 0071 Sheffield 62482 Luton 30270

191

Dawe Instruments Ltd Concord Road Western Avenue London W3 01 992 6751

Diamond H Controls Ltd Vulcan Road North Norwich NOR 85N Norfolk Norwich (0603) 45291

Drake Transformers Ltd Kennel Lane Billericay Essex Billericay (027 74) 51155

Dubilier Condenser Co (1925) Ltd Ducon Works Victoria Road North Acton London W3 01 992 8671

Duval 44 George Street Oxford Oxford (0865) 48549

Dynamco Ltd Hanworth Lane Chertsey Surrey Chertsey 2636

Dynamo & Electrical Services Ltd Unity Works Pearson Street Blackburn BBR 2ER Lancashire Blackburn (0254) 53611

EMI-Varian Ltd Hayes Middlesex 01 573 3888

Elcometer Instruments Ltd Fairfield Road Droylsden Manchester 0613705127

Elden Electronics Ltd Transformer House 370-372 York Road Wandsworth London SW18 018744131/2

Electrautom Ltd Components Division 34 High Street Tonbridge

192

Kent Tonbridge (073 22) 61234

Electrographic Ltd 50 Oldfield Circus Northolt Middlesex 01 422 5687

Electroustic Ltd 73b North Street Guildford Surrey Gu i ldford 65333

Electrosil Ltd P 0 Box 37 Pallion Trading Estate Sunderland Co Durham Sunderland (0783) 71481

Electro-Voice Products Maple Cross Industrial Estate Rickmansworth Herts Rickmansworth (79) 75381

Elliott Space & Weapon Automation Ltd (Space & Guided Weapons Division) Chobham Road Frimley Camber ley Surrey Camberley 3311

Emihus Microcomponents Ltd Heathrow House Bath Road Hounslow Middlesex 01 759 9584/5 & 9961/2

Engel & Gibbs Ltd Elstree Way Borehamwood Hertfordshire 01 953 2291

English Electric Valve Co Ltd Chelmsford Essex Chelmsford (0245) 61777

ERG Industrial Corporation Ltd Luton Road Dunstable Bedfordshire Dunstable 62241

Erie Electronics Ltd South Denes Great Yarmouth Norfolk Great Yarmouth (0493) 4911

Exacta Circuits Ltd Abbots Factory Galashiels Scotland Galashiels (0896) 3396

F R Electronics Wimborne Dorset Wimborne (020 124) 2442

Fairchild Semiconductor Ltd Kingmaker House Station Road New Barnet Hertfordshire 01 440 7311

Farnell Electronic Components Ltd Canal Road Leeds LS12 2TU Yorkshire Leeds (0532) 636311

Feedback Ltd Park Road Crowborough Sussex Crowborough 3322

Fenlow Electronics Ltd Jessamy Road Weybridge Surrey Weybridge 43978

Ferranti Ltd Hollinwood Lancashire 061 681 2000

Fieldtech Ltd No 2 Maintenance Area London (Heathrow) Airport Hounslow Middlesex 01 759 2811

Fluke International Corporation Garnett Close Watford WD2 4TT Herts Watford 27769

Foster Transformers Ltd Morden Road London SW19 01 542 2211

G E Electronics (London) Ltd Earply House 182/184 Campden Hill Road Kensington London W8 01 727 0711/3 & 5008

GEC Semiconductors Ltd Helga Electronics Ltd ITT Components Group (Capacitor Witham Ann Street Brixham Road Division) Essex South Bank Paignton Witham (077 833) 3401 Teesside Devon

Eston Grange 4691 Paignton (0803) 50762 A Gallenkamp & Co Ltd PO Box No 290 Hendry Relays Ltd ITT Components Group Europe Technico House 390-394 Bath Road (Rectifier Products Division) Christopher Street Slough Edinburgh Way London EC2 Buck i nghamshire Harlow 01 247 3211 Burnham 4611 Essex

Harlow (027 96) 26811 Gardners Transformers Ltd Hewlett-Packard Ltd Somerford Road 224 Bath Road ITT Components Group Europe Christchurch Slough (Potentiometer Division) Hants BH23 3PN Bucks Broad Lane Christchurch 2284 Slough 33341 Leeds 13

Yorkshire Graham & White Instruments

Hinchley Engineering Co ltd Pudsey (097 35) 77261 82 London Road

Pans Lane St Albans Devizes ITT Components Group Europe

Herts Wiltshire (Valve Product Division)

St Albans 59373 & 58422 Devizes 3573 Brixham Road

General Micronetics ltd Paignton

Boundary House Hird-Brown Ltd Devon

Boston Road Lever Street Paignton (0803) 50762

London W7 Bolton 01 567 8092 Lancashire ITT Electronic Services

Bolton (0204) 27311 Edinburgh Way General Radio Co (UK) ltd Harlow Cores End Road Hivac Ltd Essex Bourne End Stonefield Way Harlow (027 96) 26777 Bucks South Ruislip Bourne End 22567 Middlesex lmpectron Ltd

01 845 1288 23-31 King Street Greenpar Engineering Ltd London W3

Station Works 01 992 5388

Harlow Holsworthy Electronics Ltd

Essex Holsworthy I mpex Electrical Ltd

Harlow (027 96) 27192 Devon Market Road Holsworthy 572 Richmond

Gresham Transformers ltd Surrey Twickenham Road Honeywell Ltd 01 8761047 Han worth Great West Road

Middlesex Brentford Intel Connectors Ltd 01 894 5511 Middlesex Vereker House

01 568 9191 1-6 Gresse Street Guest International Ltd London W1P 1DF Nicholas House Howells Radio Ltd 01 637 1151 Brigstock Road Carlton Street Thornton Heath Manchester 14 Jermyn Industries Surrey CR4 7JA Lancashire Vestry Estate 01 684 9731 061 226 3411 Sevenoaks

Kent Gulton Industries (Britain) Ltd A H Hunt (Capacitors) Ltd Sevenoaks (0732) 51174 (West Instrument Division) Vulcan Way The Hyde New Addington K & N Electronics Ltd Brighton BN2 4JU Croydon CR9 OBH Cordwallis Street Sussex Surrey Maidenhead Brighton 66271 Lodge Hill (503) 2661 Berkshire

Maidenhead 22447 Hawnt & Co Ltd 112-114 Pritchett Street IRC Components Ltd Kandem Electrical Ltd Birmingham 6 Tredegar 711 & 715 Fulham Road Warwickshire Monmouthshire London SW6 021 359 4301 Tredegar 2106 01 736 2387

193

Keithley Instruments Ltd P 0 Box 43 Greyfriars Road Reading Berks Reading 56474/5

Keyswitch Relays Ltd Bendon Valley Garratt Lane Wandsworth London SW18 01 874 6454

Klippon Electricals Ltd Power Station Road Sheerness Kent Sheerness (079 56) 3093

Labgear Ltd Cromwell Road Cambridge Cambridge 47301

Lambda Electronics 21 Aston Road Waterlooville Hants Waterlooville (070 14) 51577

Leeds & Northrup Ltd Wharfdale Road Tyseley Birmingham 11 021 706 6171

Lemosa Ltd P 0 Box 306 Shoreham By Sea Sussex Shoreham (079 17) 5262

Levell Electronics Ltd Park Road High Barnet Herts 01 449 5028

Lindair Optronics (Industrial) Ltd 6/12 Tudor Place London W1 01 637 1601

Litton Precision Products Ltd 95 High Street Slough Buckinghamshire Slough 28267

Londex Ltd P 0 Box 79 207 Anerley Road London SE20 01 778 3111

194

London Electrical Manufacturing Co Ltd Beavor Lane Hammersmith London W6 01 748 2424

Claude Lyons Tubes Department 76 Old Hall Street Liverpool L3 9PX 051 227 1761

Lyons Instruments Ltd Hoddesdon Herts Hoddesdon 67161

M B Metals Ltd Victoria Road Ports lade Sussex Brighton (0273) 46981

ML Industrial Products Ltd Electronics Division 292 Leigh Road Trading Estate Slough Bucks Slough 23838

Macro-Marketing Ltd 390-394 Bath Road Slough Road Bucks Burnham (062 86) 62345

Magnetic Devices Ltd Exning Road Newmarket Suffolk Newmarket (0638) 3451

The Marconi Co Ltd Marconi House Chelmsford Essex Chelmsford (0245) 53221

Marconi Instruments Ltd Longacres St Albans Herts St Albans 59292

Matthey Printed Products Ltd William Clowes Street Burslem Stoke on Trent Staffs Stoke on Trent (0782) 85631

May Precision Components Ltd 22-27 Bowlers Croft Basildon Essex Basildon 21463

Metway Electrical Industries Ltd Metway Works Canning Street Brighton Sussex BN2 2ES Brighton (0273) 66433

Mills & Rockleys (Electronics) Ltd Garnett Place Gillibrands Industrial fstate Skelmersdale Lancashire Tawd Vale 3346

Morganite Resistors Ltd Bede Industrial Estate Jar row Co Durham Jarrow 897771

The M-0 Valve Co Ltd Brook Green Works Hammersmith London W6 01 603 3431

Mullard Ltd Mullard House Torrington Place London WC1 01 580 6633

Omega Laboratories Ltd 57 Union Street London SE1 01 407 4560

Oxley Developments Company Ltd Priory Park Ulverston Lancashire Ulverston 2621

G A Stanley Palmer Ltd Island Farm Avenue West Molesey Surrey 01 979 7254

Parmeko Ltd Percy Road Aylestone Park Leicester Leicester (0533) 832287

Pedoka Ltd Broad Street House 54 Old Broad Street London EC2 01 588 6781

Oliver Pell Controls Ltd Cambridge Row Burrage Road Woolwich London SE18 01 854 1422

Penny & Giles Ltd Mudeford Christchurch Hampshire Highcliffe (042 52) 2233

The Plessey Co Ltd Components Group Kembrey Street Swindon Wiltshire Swindon (0793) 6211

Power Development Ltd Cadmore Lane Cheshunt Hertfordshire Waltham Cross 26896

Prosser Scientific Instruments Ltd Lady Lane Hadleigh Ipswich Suffolk Hadleigh 3005/6/7

RCA Ltd (Electric Components Division) Sunbury-on-Thames Middlesex Sunbury (76) 85511

RIC Capacitors Ltd Budds Lane Romsey Hampshire Romsey 3481

Racal Electronics Ltd Western Road Bracknell Berkshire Bracknell (0344) 3244

Radiall Microwave Components Ltd Station Approach Grove Park Road Chiswick London W4 01 994 6667/8

RS Components Ltd P 0 Box 427 13-17 Epworth Street London EC2 01 253 7501

Rank Electronic Tubes Sidcup-by-Pass Sidcup Kent 01 302 0271

The Record Electrical Co Ltd Broad heath Altrincham Cheshire 061 928 6211

Reliance Controls Ltd Drakes Way Swindon Wiltshire Swindon (0793) 21351

Roberts Electronics Ltd 17 Hermitage Road Hitchin Hertfordshire Hitchin (0462) 50551

SDS (Portsmouth) Ltd Hilsea Industrial Estate Portsmouth P03 5JW Hampshire Portsmouth (0705) 62332/3 & 62180

SGS (United Kingdom) Ltd Planar house Walton Street Aylesbury Buckinghamshire Aylesbury (0296) 5977

STC Semiconductors Ltd Footscray Sidcup Kent 01 300 3333

Salford Electrical Instruments Ltd Peel Works Barton Lane Eccles Manchester M30 OH L Lancashire 061 789 5081

Sangamo Weston Ltd Great Cambridge Road Enfield Middlesex 01 336 1100

Servomex Controls Ltd Crowborough Sussex Crowborough 2151

Siemens (United Kingdom) Ltd Great West House Great West Road Brentford Middlesex 01 568 9133

Sifam Electrical Instrument Co Ltd Woodland Road Torquay Devon Torquay 63822

Simmonds & Robinson Ltd 44 Park Street Camberley Surrey Camberley (0276) 25501

The Solartron Electronic Group Ltd Victoria Road Farnborough Hants Farnborough 44433

The Sonatest Group of Companies 113 Kingsway London WC2 01 242 9211

Southern Transformer Products Ltd 301 Richmond Road Twickenham Middlesex 01 892 9141/2/3

Sprague Electric (UK) Ltd Sprague House 159 High Street Yiewsley West Drayton Middlesex West Drayton 4627

SquareD Ltd Cheney Manor Swindon Wiltshire Swindon (0793) 6222

H W Sullivan Ltd Orpington Kent Orpington 31581

Techmation Ltd 58 Edgware Road Edgware Middlesex 01 958 5636

195

Techna (Sales) Ltd Parkville House Bridge Street Pinner Middlesex 01 868 8802

Technitron Ltd Walmgate Road Perivale Middlesex 01 997 2981

Technograph & Telegraph Ltd Fleet Aldershot Hants Fleet (025 14) 3414

Tektronix UK Ltd Beaverton House P 0 Box 69 Harpenden Herts Harpenden 61251

Telephone Manufacturing Co Ltd Capacitor Division Old Meadow Road Hardwicke Trading Estate Kings Lynn Norfolk Kings Lynn 3855

Telequipment Ltd 313 Chase Road Southgate London N14 01 882 1166

Telerelay (Sales) Ltd No 1 Factory Park Drive Industrial Estate Braintree Essex Braintree 2801/3

Teradyne UK Ltd 12 Swailow Street London W1 01 437 0737

Texas Instruments Ltd Manton Lane Bedford Bedford (0234) 67466

Thorn Bendix Ltd (Electrical Components Division) Great Cambridge Street Enfield Middlesex 01 363 5353

196

Thorn Radio Valves & Tubes Ltd Brimar Sales Dept 7 Soho Square London W1 01 437 2444

Time Electronics Ltd 199a High Street Orpington Kent Orpington 32211

H Tinsley & Co Ltd Werndee Hall South Norwood London SE25 01 654 6046

Townsend Coates Ltd Coleman Road Leicester Leicester (0533) 68561

Trio Instruments Ltd Burnham Road Dartford Kent Farningham 2082

Ernest Turner Electrical Instruments Ltd Chi ltern Works Totteridge Avenue High Wycombe Bucks High Wycombe 30931

Twentieth Century Electronics Ltd Centronic Works King Henry's Drive New Addington Croydon CR9 OBG Surrey Lodge Hill (503) 2121/6

Union Carbide UK Ltd P 0 Box 2LR 8 Grafton Street London W2A 2LR 016298100

The Valiant Engineering Co Ltd 248-250 Lavender Hill London SW11 01 228 3388

Varian Associates Ltd Russell House Molesey Road Walton on Thames Surrey Walton 28766

Venner Electronics Ltd Kingston-By-Pass New Malden Surrey 01 942 2442

Vitramon Europe Wycombe Lane Wooburn Green High Wycombe Bucks Bourne End 22661

Walmore Electronics Ltd 11-15 Betterton Street Drury Lane London WC2 01 836 0201/5

E M Wareham (Measuring Systems) Ltd Wallace Way Hitchin Herts Hitchin 50436

Waycom Ltd Wokingham Road Brack nell Berks RG12 1ND Bracknell (0344) 24571

Wego Condenser Co Ltd Bideford Avenue Perivale Greenford Middlesex 01 997 4277

Weir Electronics Ltd Durban Road Bognor Regis Sussex Bognor Regis 5991

Welwyn Electric Ltd Bedlington Northumberland Bedlington (067 082) 2181/9

Westinghouse Brake & Signal Co Ltd 82 York Way Kings Cross London N1 01 837 6432

White Electrical Instruments Co Ltd Spring Lane Malvern Link Worcestersh ire Malvern 3218/9

Whiteley Electrical Radio Co Ltd Victoria Street Mansfield Nottinghamshire Mansfield (0623) 24762/5

Zenith Electric Co Ltd Pinecrest Works Cranfield Road Wavendon Bedford shire Woburn Sands (090 84) 2531/7

Accelerating voltage: (electronics, oscilloscopes) the cathode-to-viewing­screen voltage applied to a cathode­ray tube for the purpose of accelerating the electron beam.

Air cored coils: (electronics) coils with no magnetic material used in their construction; include coils wound on non-magnetic formers as well as airspaced coils.

Alpha cut-off: (electronics, semi-conductors) that frequency at the point at which the current gain of a transistor has fallen to 0·7 of its low frequency value.

Alternate mode: (electronics, oscillo­scopes) a means of displaying output signals of two or more channels by switching the channels, in sequence, after each sweep.

Anderson bridge: (electronics) a modified form of Maxwell bridge used for measuring inductance in terms of capacitance and resistance.

A.Q.L.: (electronics) a point on the operating characteristic of a sampling scheme which defines the quality level at which there is a reasonable probability (usually 0·95) that the lot will be passed as acceptable by the sampling scheme.

Audio frequency choke: (electronics) an iron-cored inductor designed to offer high resistance to audio frequency signals.

Automatic triggering: (electronics, oscilloscopes) a mode of triggering in which one or more of the triggering circuit controls are preset to condi­tions suitable for automatically displaying repetitive wave-forms. The automatic mode may also provide a recurrent sweep in the absence of triggering signals.

Auto transformer: (electronics) a wound transformer in which part of the winding is common to both the primary and secondary windings.

Bandwidth: (electronics) a statement of the frequencies defining the upper and lower limits of a frequency spectrum where the amplitude response of an amplifier to a sinusoidal waveform

Glossary

becomes 0·707 (-3dB) of the ampli­tude of a reference frequency. When only one number appears, it is taken as the upper limit.

Capacitor coupling impedance: a characteristic of capacitors having more than one capacitance element in a single container; a measure of the transfer of signal from one element to another.

Capacitor power factor: defined as the proportion of the applied a.c. signal which is dissipated as heat in the component.

Carbon composition resistors: the basic element of resistors manufactured from a mixture of carbon and resinous material. The form of the element may be either a block of the material usually moulded, or in the case of potentiometers it may be deposited in film form on a substrate.

Cavity Q: (electronic microwave devices) cavity Q is defined as 2n times the ratio of energy stored to the energy dissipated per cycle.

CFR: (electronic tubes) cold filament resistance; an important measurement on valves with multistrand filaments.

Chopped mode: (electronics, oscillo­scopes) a time sharing method of displaying output signals of two or more channels with a single cathode ray tube gun, in sequence, at a rate not referenced to the sweep.

Common mode rejection ratio (CMRR): (electronics, oscilloscopes) ratio of the deflection factor for a common-mode signal to the deflection factor for a differential signal.

Common-mode signal: (electronics) the instantaneous algebraic average of two signals applied to a balanced circuit, all signals referred to a common reference.

Common-mode signal maximum: ( elec­tronics) the largest common-mode signal at which the specific common­mode rejection ratio is valid.

Current comparator bridge: a conjugate Kelvin bridge employing the detection of zero flux for the comparison of two resistors.

of Terms

d.c. balance: (electronics, oscilloscopes) an adjustment of circuitry to avoid a change in d.c. level when changing gain.

d. c. drift (stability): (electronics, oscillo­scopes) property of retaining defined electrical characteristics for a pre­scribed period.

d.c. shift: (electronics, oscilloscopes) an error in transient response with a time constant approaching several seconds.

Deflection axis: (electronics, oscillo­scopes) the major co-ordinates passing through the centre of viewing area.

Deflection factor: (electronics, oscillo­scopes) the ratio of the input signal amplitude to the resultant displace­ment of the indicating spot (eg volts/division).

Delayed sweep: (electronics, oscillo­scopes) a sweep that has been delayed either by a predetermined period or by a period determined by an additional independent variable.

Differential amplifier: an amplifier whose output signal is proportional to the algebraic difference between two input signals.

Dual-beam oscilloscope: an oscilloscope in which the catoode ray tube produces two separate electron beams that may be individually or jointly controlled.

Dual trace: (electronics, oscilloscopes) a mode of operation in which a single beam in a cathode ray tube is shared by two signal channels; see alternate mode and chopped mode.

Dust cored coils: (electronics) coils wound onto composite material made of ferromagnetic particles coated with an insulated binder and compressed.

Electrolytic capacitors: capacitors comprising an oxide film on the surface of the positive electrode with a layer of conducting electrolyte filling the space between the oxide surface and negative electrode.

Ferrite cored coils: (electronics) coils wound on cores of sintered ferrite in which some of the iron is replaced by nickel or manganese.

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Free-running sweep: (electronics, oscillo­scopes) a sweep that runs without being triggered and is not synchronised by an applied signal.

Function generators: a multipurpose electronics signal source usually delivering square wave, triangular wave and sine wave outputs; can also be made to deliver rectangular and sawtooth waveforms.

gm: (electronics, semiconductors) low frequency mutual conductance.

Guarded input: (electronics, instrumenta­tion) means of connecting an input signal to prevent any common mode signal from causing current to flow in the input, thus differences of source impedance do not cause conversion of the common mode signal into a differential signal.

Harmonic distortion: (electronic signal generators) a measure of the impurity of the sine wave output from the generator.

Harmonic generators/frequency multi­pliers: (electronics) microwave circuits in which power at one frequency is converted to power at an harmonic frequency.

hFE: (electronics, semiconductors) common emitter de forward current gain.

hfe: (electronics, semiconductors) small signal common emitter current gain.

hie: (electronics, semiconductors) small signal common emitter input impe­dance.

hoe: (electronics, semiconductors) small signal common emitter output impe­dance

hre: (electronics, semiconductors) small signal common emitter reverse voltage ratio.

Ia: (electronic tubes) direct anode current.

la(cw): (electronic tubes) direct anode current applicable under cw condi­tions.

lamax: (electronic tubes) maximum direct current (full signal).

lao: (electronic tubes) standing direct anode current (zero signal).

ia(pk): (electronic tubes) instantaneous peak anode current.

ia(pk)mod: (electronic tubes) instantane­ous peak anode current at modula­tion crest.

leBo: (electronics, semiconductors) collector base leakage current.

lcEO: (electronics, semiconductors) collector emitter leakage current.

lnM: (electronics, power semicon­ductors) peak off state current.

le: (electronic tubes) component of direct current due to emission.

lEBO: · (electronics, semiconductors) base emitter leakage current.

IF: (electronics, power semicon-ductors) direct (continuous) forward current (limiting value).

IF(AV): (electronics, power semicon­ductors) mean forward current

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(limiting value) sinusoidal waveform, 180° conduction, resistive load.

IFRM: (electronics, power semicon­ductors) repetitive peak forward current, sinusoidal waveform.

IFsM: (electronics, power semicon­ductors) surge (non-repetitive) for­ward current, sinusoidal waveform 180° conduction.

lgt: (electronics, power semicon­ductors) gate trigger current.

In: electronics, power semicon-dictors) holding current.

I;: (electronic tubes) component of direct current due to ionised gas.

IL: (electronics, power semicon-ductors) latching current.

Ita: (electronic tubes) component of direct current due to ionised gas.

ltk: (electronic tubes) component of direct current due to leakage to cathode.

Input bias current: (electronics, linear integrated circuits) the average of the two input currents.

Input offset current: (electronics, linear integrated circuits) the difference in the currents into the two input terminals with output at zero volts.

Input offset voltage: (electronics, linear integrated circuits) that voltage which must be applied between the input terminals to obtain zero output voltage; may also be defined for the case where two equal resistances are inserted in series with the input leads.

Input RC characteristics: the d.c. resistance and capacitance to ground present at the input of an oscilloscope.

Input resistance: (electronics, linear integrated circuits) the resistance looking into either input terminal with the other grounded.

Input voltage range: (electronics, linear integrated circuits) the range of voltage which, if exceeded on either input terminal, could cause the ampli­fier to cease functioning properly.

Internal graticule: (electronics, oscillo­scopes) a scale for measurement of quantities displayed on the crt whose rulings are a permanent part of the inner surface of the cathode ray tube faceplate.

IRM: (electronics, power semiconduc­tors) peak reverse current.

IT: (electronics, power semiconductors) direct (continuous) on state current (limiting value).

IT(AV): (electronics, power semi-conductors) mean on state current (limiting value), sinusoidal waveform 180° conduction, resistive load.

ITRM: (electronics, power semi-conductors) repetitive peak on state current, sinusoidal wave form.

ITSM: (electronics, power semi-conductors) surge (non-repetitive) on state current, sinusoidal waveform, 180° conduction.

Jitter: (electronics, oscilloscopes) an aberration of a repetitive display

indicating instability of the signal or of the oscilloscope; may be random or periodic, and is usually associated with the time axis.

Kelvin double bridge: a variant of the conventional Wheatstone bridge which eliminates errors due to contact and lead resistance and is suited to the measurement of low value resistors.

Laminated iron cored coils: (electronics) coils wound around laminated ferro­magnetic material, insulated between layers to reduce eddy current losses.

Large signal voltage gain: (electronics, linear integrated circuits) the ratio of the maximum output voltage swing with load to the change in input voltage required to drive the output from zero to this voltage.

Loaded output voltage: (electronics, transformers) the value of output voltage across each secondary, with the primary connected to an a.c. supply and the secondary loaded to a rated current; ratio of loaded and unloaded output voltages gives trans­former regulation.

Magnified sweep: (electronics, oscillo­scopes) a sweep whose time per division has been decreased by ampli­fication of the sweep waveform rather than by changing the time constants used to generate it.

Metal film resistor: a resistor whose basic element is a metal film, usually a nickel alloy, which is deposited by wet chemical deposition or by vacuum processes.

Microwave band: (electronics) a commonly-used term for those frequencies falling within the range I GHz to 40 GHz.

Mixed sweep: (electronics, oscilloscopes) in a system having both a delaying sweep and a delayed sweep, a means of displaying the delaying sweep to the delaying pickoff and the delayed sweep beyond that point.

No-load power loss: (electronics, transformers) the power loss (primary copper losses and iron losses) when all secondaries are not loaded.

Output resistance: (electronics, linear integrated circuits) the resistance seen looking into the output terminal with the output at null; this parameter is defined only under small signal conditions at frequencies above a few hundred cycles to eliminate the influence of drift and thermal feed­back.

Output voltage swing: (electronics, linear integrated circuits) the peak output swing, referred to zero, that can be obtained without clipping.

Owen bridge: (electronics) a bridge widely used for the LF measurement of inductance on laminated iron core inductors.

Oxide film resistor: a resistor whose basic element is tin-oxide deposited at high temperature and containing

'doping' elements of boron or anti­mony, to control the properties of the film.

Parametric amplifier: (electronics) a low noise amplifier used at microwave frequencies.

Pirani test: a test undertaken on the heater element of electronic valves; indicates the presence of gas as well as any broken filaments.

Power consumption: (electronics, linear integrated circuits) the d.c. power required to operate the amplifier with the output at zero and with no load current.

Preferred values: (electronics, resistors) to minimise the number of different resistance values used, and hence the manufacturing costs, certain values are used wherever possible.

Pseudo-random noise generator: an electronics test instrument generating a noise signal whose pattern is repeated continuously, each cycle of the noise having carefully controlled characteristics.

Pulse droop: (electronics) the percentage of the amplitude by which the high or low voltage level sags during the period of the pulse.

PuJse jitter: (electronics) random variations of pulse width or delay usually expressed as a percentage of the pulse width or delay.

Pulse width: (electronics) the duration of a pulse, timed between 50% levels on the leading and trailing edges.

Pulse width and delay generator: (elec­tronics) a monostable or single pulse generating circuit which is triggered from the trailing edge of the clock pulse, or the pulse from another pulse width generator.

Pyrolytic carbon film resistor: a resistor whose basic element is pure carbon formed by a 'cracking' process during which the carbon is deposited at high temperature on the substrate.

rbb': (electronics, semiconductors) ex­trinsic base resistance.

rce': (electronics, semiconductors) ex­trinsic collector resistance.

re: (electronics, semiconductors) small signal resistance of emitter base junction.

ree': (electronics, semiconductors) ex­trinsic emitter resistance.

Risetime: (electronics, oscilloscopes) the interval between the instants at which the pulse amplitude first reaches specified lower and upper limits. Unless otherwise stated, these limits shall be 10% and 90% of the pulse's amplitude.

r.: (electronics, semiconductors) dynam­ic slope resistance of a zener diode.

Self-resonant frequency: (electronics, inductors) the natural frequency at which an inductor resonates resulting

from the effects of self-inductance and self-capacitance.

Sine wave sources: a general electronics term covering instruments such as test oscillators and signal generators from which a sine save signal is available.

Single sweep: (electronics, oscilloscopes) operating mode for a triggered-sweep oscilloscope in which the sweep must be reset for each operation thus prevent­ing unwanted multiple displays.

Smith's chart: (electronics) a trans­mission line impedance chart.

Supply voltage rejection ratio: (elec­tronics. linear integrated circuits) the ratio of the change in input offset voltage to the change in supply vol­tage producing it.

Sweep: (electronics, oscilloscopes) an independent variable of a display; unless otherwise specified, this variable is a linear function of time, but may be any quantity that varies in a definable manner.

Sweep hold off: (electronics, oscillo­scopes) the interval between sweeps during which the sweep and/or trigger circuits are inhibited.

td: (electronics, semiconductors) tran­sient delay time.

ts: (electronics, semiconductors) tran­sient storage time.

Test oscillator: an instrument generating test signals over a fairly narrow fre­quency band with very good frequency and amplitude stability and very little distortion.

tr: (electronics, semiconductors) tran­sient fall time.

9Ja: (electronics, semiconductors): thermal resistance from junction to air.

9ic: (electronics, semiconductors) thermal resistance from junction to case.

Time base: (electronics, oscilloscopes) the sweep generator in an oscilloscope that generates the time function, which is usually linear and expressed in sec/em.

Time base accuracy: (electronics, oscillo­scopes) accuracy of the time base usually expressed in terms of average rate error as a percent of full scale.

torr: (electronics, semiconductors) tran­sient 'OFF' time.

ton: (electronics, semiconductors) tran­sient 'ON' time.

tpd: (electronics, semiconductors) tran­sient propagation delay.

tq: (electronics, power semiconductors) circuit commutated turn off time.

Truth table: a table drawn-up for an electronic logic circuit which shows the Ol,ltput state of that circuit for every combination of input signal.

Transformer input current: the current drawn from an a.c. supply when the transformer secondary windings are

either loaded or not loaded with their rated currents.

T-R ceUs: (electronics) transmit-receive devices, are used for receiver protec­tion and switching.

Trigger: (electronics, oscilloscopes) a pulse used to initiate some function.

Triggering level: (electronics, oscillo­scopes) the instantaneous level of a triggering signal at which a trigger is to be generated.

Triggering slope: (electronics, oscillo­scopes) the positive going ( + slope) or negative slope (- slope) portion of a triggering signal from which a trigger is to be derived.

Varactor diodes: (electronics) a broad class of semiconductor diodes used for electronic tuning, harmonic generation and parametric amplifica­tion.

VBE: (electronics, semiconductors) com­mon emitter unsaturated base emitter voltage.

VBE(sat): (electronics, semiconductors) common emitter base saturation voltage.

VcBo: (electronics, semiconductors) collector base breakdown voltage.

VcE<sat): (electronics, semiconductors) common emitter collector saturation voltage.

VcEo: (electronics, semiconductors) collector emitter breakdown voltage.

Vn: (electronics, power semiconductors) continuous (direct) off state voltage.

VnRM: (electronics, power semicon­ductors) repetitive peak off state voltage.

VnsM: (electronics, power semicon­ductors) non-repetitive peak off state voltage.

VnwM: (electronics, power semicon­ductors) crest working off state voltage.

VEBO: (electronics, semiconductors) base emitter breakdown voltage.

VF: (electronics, power semiconductors) peak forward voltage.

Vgt: (electronics, power semiconductors) gate trigger voltage.

Va: (electronics, power semiconductors) continuous (direct) reverse voltage.

VRRM: (electronics, power semicon­ductors) repetitive peak reverse voltage.

VRSM: (electronics, power semicon­ductors) non-repetitive peak reverse voltage.

VawM: (electronics, power semicon­ductors) crest working reverse voltage.

vswr: (electronics) the symbol for vol­tage standing wave ratio, the ratio of incident to reflected voltage.

Yre: (electronics, semiconductors) com­mon emitter forward transfer ratio mutual conductance.

Vie: (electronics, semiconductors) com­mon emitter input admittance.

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