Understand Electronics, 2nd Edition

16

Oscillating circuits

The output voltage of an oscillating circuit alternates between two peak values at regular intervals of time. It may switch sharply between the two extreme values, in which case we call it a square-wave oscillator, but the output waveform may have other regular shapes such as sawtooth, triangular or sine waves. The time taken for one complete oscillation or cycle is known as the period of the oscillation. The rate of repetition of the waveform is known as the frequency. Frequency is expressed in hertz (symbol, Hz) where 1 Hz is equal to 1 cycle per second. Period and frequency are related by the equation:

$\mathrm{frequency}=\frac{1}{\mathrm{period}}$

For example, if the period is 1 ms, the frequency is 1 kHz.

In most, but not all, of the oscillators described ...