A multivibrator is an
electronic circuit
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. It is a type of electri ...
used to implement a variety of simple two-state
devices such as
relaxation oscillator
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. on Peter Millet'Tubebookswebsite The circuit consists of a feedba ...
s,
timer
A timer is a specialized type of clock used for measuring specific time intervals.
Timers can be categorized into two main types.
The word "timer" is usually reserved for devices that counts down from a specified time interval, while devices th ...
s, and
flip-flops
Flip-flops are a type of light sandal, typically worn as a form of casual footwear. They consist of a flat sole held loosely on the foot by a Y-shaped strap known as a toe thong that passes between the first and second toes and around both side ...
. The first multivibrator circuit, the astable multivibrator
oscillator, was invented by
Henri Abraham and
Eugene Bloch during
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
. It consisted of two vacuum tube amplifiers cross-coupled by a resistor-capacitor network.
They called their circuit a "multivibrator" because its output waveform was rich in
harmonics
A harmonic is a wave with a frequency that is a positive integer multiple of the '' fundamental frequency'', the frequency of the original periodic signal, such as a sinusoidal wave