Trigonometric relationships , Transistor circuits and characteristics and Transistor testing.

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Trigonometric relationships

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Transistor circuits and characteristics

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Wavelength-frequency conversion table

Metres to Kilohertz

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Transistor testing

Although the following table cannot be used to accurately find the characteristics of an unknown transistor, if it is stepped through it will indicate whether the transistor is good or bad. Use of a meter with a 100 times resistance scale is assumed, which does not have a high current output.

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Radio interference

The Radio Investigation Service of the Department of Trade and lndu.stry now devotes its efforts against those operating radio transmitters without a licence ('pirates') and those who abuse the terms and conditions of the licence. Far less time is spent investigating complaints of interference by owners of domestic radio and electronic equipment, which is prone to pick up interference because of unsuitable internal circuit screening, poor quality design, inadequate maintenance, improper tuning and, with TV, the lack of a suitable high gain outside aerial. British Standard BS905 now provides minimum immunity standards for TV sets and will be incorporated into legislation making it an offence to manufacture. sell, hire or import TV receivers which do not comply with this standard.

Owners of TV sets, radios and other domestic equipment are expected to deal with interference problems themselves, with the assistance of the dealer, hire company or manufacturer, aided by a booklet issued by the Department of Trade and Industry and available from Post Offices.

If the DTI Radio Interference Service is called out there will be a 'call-out' fee of £21. A log detailing the interference must be provided. If this is not available or if the TV set operates from an indoor aerial the RIS will not cooperate. From 1987 the RIS will only investigate if the dealer or hirer declares that he cannot deal with the problem.

Astronomical data

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Resistivities of selected metals and alloys

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