In
electronics a
relaxation oscillator is a
nonlinear electronic oscillator circuit that produces a
nonsinusoidal repetitive output signal, such as a
triangle wave or
square wave. The circuit consists of a
feedback loop containing a switching device such as a
transistor,
comparator,
relay,
op amp, or a
negative resistance device like a
tunnel diode, that repetitively charges a
capacitor or
inductor through a resistance until it reaches a threshold level, then discharges it again. The
period of the oscillator depends on the
time constant of the capacitor or inductor circuit. The active device switches abruptly between charging and discharging modes, and thus produces a discontinuously changing repetitive waveform. This contrasts with the other type of electronic oscillator, the harmonic or
linear oscillator, which uses an
amplifier with feedback to excite
resonant oscillations in a
resonator, producing a
sine wave. Relaxation oscillators are used to produce low frequency signals for applications such as blinking lights and
electronic beepers and in
voltage controlled oscillators (VCOs),
inverters and
switching power supplies,
dual-slope analog to digital converters, and
function generators.