Electrons in solids. and semiconductor devices

Uses of transistors in circuits

Uses of transistors in circuits In amplifier circuits in radios, record players and similar devices, the ‘old-fashioned’ thermionic diode and triode have been superseded by semiconductor diodes and transistors. These components are much smaller and lighter. They operate from low voltages of only a few volts, compared with tens or hundreds of volts for thermionic devices. For this …

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Use of a reed switch and transistor in a burglar alarm

Use of a reed switch and transistor in a burglar alarm If the LOR in Fig. 45.5 of the thermistor in Fig. 45.17 is replaced by a reed switch we should have the basics of an efficient burglar alarm (see Fig. 45.18). A reed switch consists of two springy reeds made of magnetic material with contacts which …

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Power pack. Smoothing

Power pack. Smoothing Half-wave and full-wave rectified alternating current is very useful for some purposes, e.g. charging secondary cells. However, it cannot be used to replace a direct current source in radio or similar electrical equipment, as it gives rise to intolerable hum. This hum may be reduced considerably by connecting a smoothing capacitor in parallel with the output. The …

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To plot the characteristic curve for a semiconductor diode

To plot the characteristic curve for a semiconductor diode Diodes usually available for study in this experiment are likely to have maximum current outputs of 10 to 500 mA, rarely more than 1 A. Reverse bias voltages of up to 25 V or 100 V, or even more, may be permissible without harming the diodes. However, if the …

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The semiconductor diode

The semiconductor diode We have already mentioned semiconductors and the solid-state diode on page 408. The materials usually used in their manufacture are either silicon or germanium which have been alloyed or doped with small quantities of a chosen impurity. According to the impurity chosen, they are classed as either p-type or n-type, where the letters p and …

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