What is "multivibrator"

n. (context electronics English) An electronic circuit used to implement a variety of simple two-state systems such as oscillators, timers, and flip-flops.

A multivibrator is an electronic circuit used to implement a variety of simple multi-state systems such as oscillators, timers and flip-flops. It is characterized by two amplifying devices ( transistors, electron tubes or other devices) cross-coupled by resistors or capacitors. The name "multivibrator" was initially applied to the free-running oscillator version of the circuit because its output waveform was rich in harmonics.

Some common types of multivibrator circuits are:

• Astable, in which the circuit is not stable in either state —it continually switches from one state to the other. It functions as a relaxation oscillator.
• Monostable, in which one of the states is stable, but the other state is unstable (transient). A trigger pulse causes the circuit to enter the unstable state. After entering the unstable state, the circuit will return to the stable state after a set time. Such a circuit is useful for creating a timing period of fixed duration in response to some external event. This circuit is also known as a one shot.
• Bistable, in which the circuit is stable in either state. It can be flipped from one state to the other by an external trigger pulse. This circuit is also known as a flip-flop. It can be used to store one bit of information.

Multivibrators find applications in a variety of systems where square waves or timed intervals are required. For example, before the advent of low-cost integrated circuits, chains of multivibrators found use as frequency dividers. A free-running multivibrator with a frequency of one-half to one-tenth of the reference frequency would accurately lock to the reference frequency. This technique was used in early electronic organs, to keep notes of different octaves accurately in tune. Other applications included early television systems, where the various line and frame frequencies were kept synchronized by pulses included in the video signal.