Product Guide 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. 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 EElectronics (London) Ltd Guest International ltd Hawnt & Co Ltd A H Hunt (Capacitors) Ltd I RC Components Ltd ITT Components Group (Capacitor Division) lmpectron 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) Radiosparas RIC Capacitors Ltd Salford Electrical Instruments Ltd Siemens (United Kingdom) Ltd Sprague Electric (UK) Ltd 161
Transcript
Product Guide
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.
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 I RC Components Ltd ITT Components Group (Capacitor Division) lmpectron 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) Radiosparas RIC Capacitors Ltd Salford Electrical Instruments Ltd Siemens (United Kingdom) Ltd Sprague Electric (UK) Ltd
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Techmation Ltd 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) lmpectron 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 Radiospares Reliance Controls Ltd Salford Electrical Instruments Ltd Sprague Electric (UK) Ltd Walmore Electronics Ltd Waycom Ltd Welwyn Electric Ltd
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
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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 lgranic 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 Corporation Ltd F R Electronics
(A Division of Flight Refuelling) Hendrey Relays Ltd lmpex Electrical Ltd ITT Components Group Europe 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 Square D 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
A F Bulgin & Co Ltd By-Pass Road Barking Essex 01 -594 5588
Cambion Electronic Products Ltd Cambion Works Castleton Nr Sheffield S30 2WR Hope (Derbyshire) (043 32) 406
CGS Resistance Co Ltd Marsh Lane Gosport Street Lymington Hampshire Lymington (059 07) 3282
Chelmar Valve Co 130 New London Road Chelmsford Essex Chelmsford (0245) 55296
Circaprint Ltd Diamond H Controls Ltd Electrosil Ltd 17-21 Foster Street Vulcan Road North PO Box 37 Maidstone Norwich NOR 85N Pallion Trading Estate Kent Norfolk Sunderland Maidstone 55484 Norwich (0603) 45291 Co Durham
Sunderland (0783) 71481
C P Clare Electronics Ltd Jack Davies (Relays) Ltd Stonefield Way 9-10 Mallow StreP.t Electro-Voice Products South Ruislip Old Street Maple Cross Industrial Estate
Cole Electronics Ltd Dubilier Condenser Co (1925) Ltd Engel & Gibbs Ltd
Lansdowne Road Ducon Works Elstree Way
Croydon CR9 2HB Victoria Road Borehamwood
Surrey North Acton Hertford shire
01-686 7581 London W3 01-953 2291 01-992 8671
Colvern Ltd English Electric Valve Co Ltd Spring Gardens Duval Chelmsford Romford 44 George Street Essex Essex Oxford Chelmsford (0245) 61777 Romford 62222 Oxford (0865) 48549
Cox Engineering Co Ltd ERG Industrial Corporation Ltd Luton Road
14 Park Lane Dynamo & Electrical Services Ltd Dunstable Sheffield S10 Unity Works Bedfordshire Sheffield 62482 Pearson Street Dunstable 62241
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
Whiteley Electrical Radio Co Ltd Victoria Street Mansfield Nottinghamshire Mansfield (0623) 24762/5
Zenith Electric Co Ltd Pinecrest Works Cranfield Road Wavendon Bedfordshire Woburn Sands 2531 /7
Glossary of Terms
Absolute maximum system: a system of electrical and thermal ratings for components under which the figure given for a particular parameter cannot be exceeded without the risk of permanent damage to the component.
Accelerated test: a test applied to components in which the level of applied stress exceeds that stated in the reference conditions in order to shorten the time required to observe the stress response of the item.
Acoustic surface wave devices: single crystal semiconductor devices in which amplification is achieved by passing a signal along the surface of a semiconductor chip as a mechanical wave which interacts with the electrical properties of the crystal, giving an increase of the power transfer.
AHoy diode: a diode manufactured from a semiconductor wafer to which contact leads are welded.
Amplification factor: (elec) thermionic valves; the ratio of the change in anode voltage to the change in control grid voltage producing that effect.
Amplitude modulation: (elec) imparting intelligence to a radio carrier wave by causing the amplitude of the wave to vary in sympathy with the amplitude of the modulating waveform.
Analogue computing: an electronic computing system in which the quantities to be computed are represented by the magnitude of generated voltages.
APL: The abbreviation generally recognised for Approved Parts and Materials List; this list is the result of discussions between purchaser and manufacturer on a particular
project and relates to components and materials which are acceptable to both parties.
Aquadag: a trade name for a graphitised carbon conductive coating applied to the inner surface of cathode ray tubes and some other thermionic valves.
Armature type relays: a term used to cover the broad spectrum of electromagnetic relays which have an armature hinged or pivoted to the fixed yoke of the relay; operating from either a.c. or d.c.
Assessed: electronics reliability; a statistical adjective meaning that result determined as a limiting value of the confidence interval with a stated probability level based, usually, on the same data as the observed result on nominally identical items.
atta: prefiix used in metric units giving a value of lQ-18; symbol a.
Base: semiconductors; the region between the emitter and collector in a junction transistor.
Betatron: a circular electron accelerator employing magnetic induction as the accelerating medium.
Bifilar winding: a method of producing non - inductive wound electronic components by winding half the turns back over themselves.
Bound joints: an electrical connection method in which the lead wire is laid parallel to the length of the terminal adjacent to the wide face and secured by several turns of wrapping wire.
Burn-in: the operating of electronic components for a period of some hours prior to their integration in a circuit under varying temperature conditions which simulate their eventual operational environment.
Capacitor: (electrical) basically two conductors separated by an insulating layer; a component possessing appreciable capacitance, often a multilayer unit; formerly termed a condenser.
Carbide cermets: cermets based mostly on titanium carbide with nickel, cobalt, or iron based alloys for the metal.
Carbon composition resistors: resistors in which the resistive element consists of finely divided carbon, an inert filler and a synthetic resin binder pressed into the form of a rod and cured; the ends may be sprayed with metal and have soldered leads or a metal end cap, alternatively leads may be embedded in the rod before pressing.
Catastrophic failure: a classification of failure in electronics devices which covers both suddenness and degree; a catastrophic failure is both sudden and complete.
CDL: (elec) core diode logic. Clark ceO: a standard cell used in
high accuracy measuring bridges etc where current requirements are minimal; mercury-zinc construction.
Coil constant: the ratio of an inductive coil's reactance to its effective resistance at a given frequency.
Coil loading: (elec) improving the performance of a transmitting line by the insertion of inductive coils at predetermined intervals.
Commercial relays: electrical relays designed to perform reliably under conditions likely to be met in normal applications.
Complete failure: a classification as to the degree of failure of an electronics device, used to cover failures resulting from deviations in
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the characteristics beyond specified limits such as to cause a complete lack of the required function.
Conductivity: (thermal) transfer of heat through a medium without apparent movement, by intermolecular energy effects (heat units I unit area and time, eg J fm2s or W/m2);
(electrical) passage of current through a medium by movement of charge carriers (eg electrons and/ or ions) under the influence of a potential gradient; reciprocal of volume resistivity; unit of conductance, mho; of restivity, ohm.
Conformal coatings: coatings using plastics varnishes with the addition of plasticisers which are sufficiently flexible to allow the coated component to move slightly or expand without damage.
Constant failure rate period: a term used in electronics reliability concepts which refers to that period in the life of an item during which the failures occur to some items at an approximately uniform rate.
Contact: (electrical) device to complete part of a current-carrying circuit; types include static (stationary in normal use), sliding (eg brush contacts on rotating machines, wiper or slide wires or rails, pantographic collectors), opening (switching devices).
Continuous rating: a rating specifying electrical loads which can be handled by a device for indefinitely long periods.
Cracked carbon resistors: cracked or pyrolytic carbon film resistors consisting of ceramic rods over which a hydrocarbon vapour has been passed and decomposed depositing a thin carbon film; resistance value is adjusted by cutting a heliw groove through the carbon film and partially through the ceramic.
Cryogenics: study of phenomena at very low temperatures.
Crystal can relays: hermetically sealed relays with balanced armatures and housed in enclosures originally designed for the quartz crystal of oscillators.
Crystal controUed osciUator: an electronic oscillator whose frequency is locked to the natural frequency of vibration of a piezo· electric crystal.
Cryotron: (electrical) a logic element consisting of two thin strips of superconducting material in close proximity; a relay or miniature electronic swich.
CfL: (elec) core transistor logic. Current gain: ratio of current in the
collector circuit to the current in the emitter circuit of a transistor; symbol a:
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CW transmission: continuous wave transmission; information transmission by means of transmitted radio waves which do not vary in either frequency or amplitude.
Damped oscillation: a oscillatory function of successively decreasing cycle amplitude.
DCL: (elect) direct coupled logic. Degradated failure: a classification of
failure in an electronics device which covers both suddenness and degree; a degradation failure is both gradual and partial.
Delay line: (electronics) a transmission line of such characteristics as to retard the time of arrival of a transmitted signal.
Demodulation: the process of extracting intelligence from a transmitted radio wave; also detection.
Derating: the process of operating a component or system at parameters lower than the maximum permissible levels, usually to offset the effect of unusual or extreme conditions.
DiJferential capacitor: a two-part variable capacitor designed so that tuning the rotor increases the capacitance of one section while decreasing the other.
DIP: dual in line package. Double-throw switch: a mechanical
switch where connection may be made by switching the blade into either of two sets of contacts.
Drift: (electronics) the change, usually associated with time, of any parameter of a component or characteristic of a circuit.
Dry reed relays: a coil acting on one or more magnetic reed switches which themselves consist of two ferromagnetic metal reeds, sealed into a glass capsule and aligned to give a slight overlap at the contact area.
Dry units: electronics-wound components; coils and transformers to which no further treatment is applied after assembly.
DTL: (elec) diode transistor logic. Dual-in-line package (DIP): a
packaged integrated circuit so called because it has two rows of in-line pins; the pins are commonly 2.5 mm apart and semi-rigid to allow the device to be easily inserted into PCBs and flow soldered; available with 16 and 24 leads.
Duplex radio transmission: the simultaneous transmission of two intelligence-bearing radio waves on one carrier wave.
Dynode: an electrode in a thermionic valve or similar device whose function is secondary emission.
Early failure period: a term used in electronics reliability concepts which refers to the early period in the life
of an item, beginning at some stated time and during which the failure rate of some items is decreasing rapidly.
ECL: (elec) emitter coupled logic. Electroluminescence: a property pos
sessed by certain solids which causes them to emit light when placed in a varying electric field.
Electron gun: collective term for the emitter and grids of a cathode ray tube responsible for the generation, acceleration and initial focusing of the electron beam.
Electro-optical tubes: a term generally recognised as covering cathode ray tubes, camera tubes, storage tubes and image intensifiers.
Encapsulation: sealing (potting) of an item or structure within, typically, a plastics material for protection from environment; widely used to contain electronics components.
Extrapolated: electronics reliability; a statistical adjective relating to an extension of the observed or assessed results with durations of stress conditions different from those applying to the conditions of the assessed state.
Failure: electronics; the termination of the ability of an item to perform its required function.
Failure rate: electronics; a term qualified by a statistical adjective, ie observed, assessed, extrapolated and predicted; the proportion of failures in a particular period of time under stated conditions.
Feedthrough capacitors: capacitors used to decouple and illter RF circuits.
femto: prefix used in metric units units giVmg a value of lQ-15; symbol f.
Ferrimagnetic (feiTomagnetic): pro~
perty of a material that has a relatively high permeability which varies with flux density; notably iron and ferrous alloys, compounds such as ferrites.
Ferrite: (electronics) ferrimagnetic oxide material which exhibits a combination of insulating and magnetic properties useful in electronics applications; often a complex oxide of eg rare-earth metals and iron. (Metallurgy) a metallic solid solution based on alpha-iron.
FET: (elec) field effect transistor. Flashed filaments: electronics con
struction; carbon illaments which have been subjected to a flashing process in a carbon-containing atmosphere to improve the uniformity of their cross-section.
Flat pack: (elec) a packaged integrated circuit, commonly with 14 leads available and measuring approximately 6 mm x 6 mm.
Flux jump: (electrical) collapse of current path in a superconductor which has been driven into the normal state by heat generated from movement of current path, eg near limiting current density of a material.
Fragility factor: an electronic equipment rating relating to its handling in mechanical transit; it is determined by a programme of drop tests to determine the deceleration level which will cause damage to the packaged equipment.
Frequency modulation: imparting intelligence to a radio carrier wave by causing the frequency of the wave to vary in sympathy with the amplitude of the modulating waveform.
Full wave rectifier: an electronic circuit which converts each half cycle of alternating current into direct current.
Function generators: generators which deliver an electronic output signal which is a function of the input voltage, ie sine, square, logarithmic.
Fuse: (general) melt; (electrical) device used to protect equipment from overload; a conductor that fuses (ie breaks circuit) at specified load; energy of fusion is proportional to the square of the cross sectional area of the conductor.
Garnet: (mineral) groups of materials (including semi-precious gemstones) of cubic crystal structure; term also used to describe crystallographic class of materials, eg ferrites.
giga: prefix used in metric units giving a value of 109; symbol G.
Gradual fallure: a classification of failure in electronics which applies when the failure could be anticipated by prior examination.
IGFET: (elec) insulated gate field effect transistor.
lgnitron: (electronics) mercury-arc valve using a pool of mercury as the cathode and capable of rectifying large currents.
Impulse relays: usually a single coil device; the armature alternatively transfers the contact system from one state to another by means of a mechanism holding the armature in one of two states.
Inherent weakness fallures: a classification of failure in electronics in which the failure is attributable to a weakness inherent in the item itself when subjected to stresses within the stated capabilities of the item.
Inrush loads: instantaneous currents experienced on the closing of relay contacts, many times greater than the steady-state value of the load.
Inverter: electronic circuit or device
for converting d.c. to a.c. Ion: electrically charged particle (of
atomic or molecular size) which can transport electricity by its mobility through a fluid medium, eg electrolyte or gas.
kilo: prefix used in metric units giving a value of 103; symbol k.
Klystron: electronic valve for generating or amplifying microwave quantities.
Lambertian surface: electro-optics; a perfectly diffuse surface which has a constant radiance independent of the viewing direction.
Laser: Light Amplification using Stimulated Emission Radiation; a device which produces a coherent beam of light which is very intense and almost parallel; various types of laser are gas, crystal and injection.
Latching relays: relays designed to hold the contacts in the energised position after the power has been removed from the energising coil.
Lateral p-n-p: electronics semiconductor device; generally a specially designed low beta transistor used in a linear circuit.
Lidar: term for light detection and ranging using lasers; operating ·on the same basic principles as radar.
Light emitting diode: a low power light source in the form of a semi· conductor p-n junction diode; subject to continuing development.
lSI: generally recognised abbreviation for large scale-integration; used in the electronics industry to cover multifunction integrated circuits.
Luminous emittance: electro-optics; the luminous flux output per unit surface area.
Magnetron: a complex electronic valve capable of producing high output powers at microwave frequencies.
MAS: metal alumina semiconductor. Mass resistivity: (electrical) for a
material at a given temperature, the product of the density and volume resistivity.
Mean life: electronics; defined as the mean value of the lengths of observed times to failure of all specimens in a sample of items under stated stress conditions; MTIF and mean life apply only to non-repaired items, mainly components.
Mechanical interlocking relays: essentially two-coil three-position devices, usually consisting of two relays on a common base with a mechanical link preventing the operation of one relay whilst the otb.er is energised.
mega: prefix used in metric units giving a value of 106; symbol M.
Mercury switch relays: relays con-
sisting of one or more mercury switches, tilted by the movement of the relay armature.
Mercury wetted reed relays: a form of reed switch having a pool of mercury at its base which by capillary action wets the contact faces.
Metal film resistors: resistors formed by the deposition of a thin metal film on a cylindrical ceramic substrate and the cutting of a helical groove between the ends; the film is usually lacquered and
. the whole encapsulated for protection.
Metal glaze (cermet) resistors: resistors formed by depositing a coating of micrometric-sized glass and metal particles dispersed in a viscous organic substance onto a ceramic substrate and firing; the organic substances bum-off and the glass fuses and bonds to the substrate.
Metal oxide film resistors: the film is formed by the hydrolysis of an aqueous solution of stannic chloride on a glass, ceramic or glazed ceramic rod at red heat; resistivity and TCR is modified by the addition of a small proportion of antimony or boron compounds.
micro: prefix used in metric units giving a value of l0-6; symbol P.·
Microwave switching tubes: cold cathode gas filled tubes used for switching duties in radar applications.
Microwave tubes: a term generally recognised as encompassing families of tubes (valves) working in the UHF bands; covers triodes, travelling wave tubes, magnetrons, modulators, klystrons and microwave switching tubes.
Military relays: ( elec) a general term covering relays designed to operate under extremes of environmental conditions.
Misuse fallures: a classification of failure in which the failure is attributable to the application of stresses beyond the stated capabilities of the item.
Mixed dielectric capacitors: capacitors whose dielectric is a combination of plastic films and paper.
Moire fringe: the bands of light and shade which appear when a beam of light passes through regularly spaced grids having the same pitch; used in transducers for linear measuring techniques.
MOS: (elec) generally recognised abbreviation for metal oxide silicon semiconductor 'devices.
MTBF: mean time between failures (electronics etc); a term which refers to repairable items and defined as: for a stated period in the life of an item, the mean value
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of the lengths of observed times between consecutive failures under stated stress conditions.
MITF: mean time to failure (electronics etc); defined as: for a stated period and under stated stress conditions the total cumulative observed time divided by the total number of failures in the population during the period.
oano: prefix used in metric units giving a value of lQ-9; symbol n.
Observed: electronics reliability; a statistical adjective meaning that result which is obtained by observing the number of actions which occur in a certain time to a single item or a number of items.
Operatiooal amplifiers: directly coupled electronic amplifiers of infinitely high gain capable of operating at very low frequencies, the basic unit of analogue computation systems.
Oxide cermets: cermets based mainly on alumina or magnesia with molybdenum, chromium, nickel, tungsten or tungsten alloys as the metal.
Partial fallure: a classification as to the degree of failure, used in electronics to cover failures which result from deviations in the characteristics beyond specified limits of a device, but not such as to cause a complete lack of the required function.
Partial redundancy: a system of elements in which a certain specified number can fail without causing a system failure; a system of m elements in which not more than n elements can fail without causing a system failure is said to be in an 'n-out-of-m' partial redundancy.
Particle accelerator: a device for accelerating electrically charged atomic or subatomic particles to high energies.
Patchboard: an operator-accessible board used in analogue computers to interconnect internal circuits by arranging patchcords and plugs in a suitable configuration.
Photodiode: a semiconductor device constructed so that light can reach the junction region; the resultant electrons released by the incident light are usefully collected by biasing the diode.
Photoelectric eDUSSion: phenomena whereby certain substances emit electrons when light falls on them.
Photomultiplier: basically a photocell employing additional emitting electrodes called dynodes.
pico: prefix used in metric units giving a value of 10·12; symbol p.
Predicted: electronics reliability; a statistical adjective relating to -estimating the particular reliability
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characteristics of an equipment based on the observed, assessed or extrapolated reliability (or failure rate) of HS parts, and taking into account the circuit design.
Pulse width modulation: a method of transmitting intelligence employing electrical pulses of equal amplitude but of varying time duration.
'Q' factor: the measure of the 'goodness' factor of a component; for an inductive coil the ratio of the reactance to the total resistance at that frequency.
Reftow soldering: a method of making electrical connections whereby components whose leads have been previously tinned may be assembled and connection made by reflowing the solder with applied heat.
Reliability: electronics; the formal definition of reliability is: the ability of an item to perform a required function under stated conditions for a stated period of time; a further definition for ·numerical expression is, the characteristic of an item expressed by the probability that it will perform a required function under stated conditions for a stated period of time.
Resistance welded joints: an electrical connection made by fusing together the conductors being joined; the welding heat is generated by a current passing through the resistance of the joint, placed between the welding machine electrodes, and pressure is obtained by the mechanical forces on the electrodes themselves.
Resistivity: (electrical) usually volume or specific resistivity of a material; resistance (ohm) of block of unit length and cross-sectional area.
Saturation magnetisation: maximum magnetic flux density in a material; important basic property in electronics applications, eg of ferrites; expressed in tesla (lT = 10-4 gauss).
Schottky barrier diode: a semiconductor device in which the rectifying junction is made between an n-type semiconductor and a metal contact and where the work function of the metal is greater than that of the semiconductor; capable of rectifying extremely high frequencies.
Screening test: a test which is intended to remove unsatisfactory items or those likely to exhibit early failures.
Secondary breakdown voltage: semiconductors; this is the voltage at which complete breakdown of the semiconductor function occurs.
Setmaker: a term used in the electronics consumer entertainment industry to cover the manufacturer of radio, television sets, etc.
Shrunken raster: a method of measuring line width (electronic display devices) in which a raster having a known number of lines is reduced in ampitude until the lines appear to merge; the width is then taken as being the raster height divided by the number of lines.
SIC: (elec) silicon integrated circuit. Side contact connector: a type of
connector used in association with PCBs containing a number of spring fingers which made contact with pads on the board
Solenoid actuated relays: alternatively called relay contactors, these operate on the principle of a soft iron core being attracted to a pole face situated in the centre of the coil, the coil normally being surrounded by a magnetic m<tterial.
Sonar: a system of sound navigation and ranging utilisin•· the transmission and reception oi high frequency electrical pulses.
Spectral radiant emittance: a radiometric quantity, defined as the radiant emittance per unit wavelength interval aw 1 8)...
Spectral radiant power: a radiometric quantity, defined as the radiant power per unit wavelength interval 8P 1 8).. or the radiant power per unit frequency interval 8P I 8v; symbols P).. and Pv; units Wlpm and WIHz.
Spinel: (mineral) group of materials of cubic crystal structure; term also used to describe crystallographic class of materials eg ferrites.
Standby conditions: in electronics equipment employing thermionic devices the term refers to the conditions when heater power only is supplied to the equipment.
Sudden fallure: a classification of failure in electronics used when the failure could not be anticipated by prior examination.
Sustaining collector voltage: semiconductors; the device's collectoremitter voltage after breakdown has occurred.
TCR: (electrical) temperature coefficient of resistance; usually positive for pure metals, but some alloys may have negative TCR over limited temperature range; can be used as measure of purity of a metal, eg platinum.
Telegraphy: a communications system of transmitting information by using a suitable code.
Telephony: a direct information transmtSS1on system employing an electrical representation of speech; frequency range 300-3500 Hz approx.
tera: prefix used in metric units giving a value of 1012; symbol T.
TFFI': (elec) thin film field effect transistor.
Thermoelectric cycle: the phenomena resulting from the flow of direct current through a junction of dissimilar metals; one junction is cooled, the other heated.
Thermoelectric generation: the practical application of the electromotive force produced when a junction between dissimilar conductors is heated.
Thick film resistors: formed by screen printing an ink (consisting of finely divided particles of a metal or metal oxide, fine glass powder and a binder dispersed in an organic liquid) onto a ceramic substrate and subsequent drying and firing.
Transducer: a device used to convert the magnitude of one parameter into the magnitude of another paramater, usually more easily measured.
Travelling-wave tube: electronic valve in which microwave signals are amplified by interacting with an electron beam.
TRL: (elec) transistor-resistor logic. TTL: (elec) transistor-transistor logic. Type-tests: tests carried out by the
electronic component manufacturer intended to prove the design of a particular component for its application.
Ultrasonic soldering: a soldering method utilising high frequency vibration energy to provide local heat, avoiding the formation of metal oxides.
Unipolar transistors: an insulated gate field effect transistor consisting of a thin layer of the semiconductor, cadmium sulphide, on an insulating substrate with metal contacts forming the source and drain terminals.
Vacuum deposition: the process of growing thin solid films in a
vacuum; the two basic processes are vacuum evaporation and cathodic sputtering.
Video amplifier: wide band electronic amplifier capable of handling video frequency signals.
Waveguides: hollow metal tube-like structures used for transmitting electrical energy in the frequency range 1000 to 200 000 MHz.
Wear-out failure period: a term used in electronics reliability concepts which refers to that period during the life of items when the failure rate of some items is rapidly increasing due to deterioration processes.
Wrapped joints: a wrapped electrical joint is one in which a rectangular pin or stake is tightly bound several times with wire; a special tool is used to make the wrap and this method breaks down any surface film on the pin or the wire.
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