# What is a Bistable Multivibrator Circuit?

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Editorial Team - everything PE

Feb 9, 2024

A bistable multivibrator or flip-flop circuit is a type of electronic circuit that has two stable states and can be used to store a binary bit of information (0 or 1). Unlike monostable and astable multivibrators, which have one or no stable states, a bistable circuit remains in one of its stable states until an external input is applied to trigger a transition to the other stable state. These multivibrators are use in digital electronics, forming the basis of memory elements in computers, registers, and other storage devices.

Working Principle

Circuit Diagram of a Bistable Multivibrator Circuit
The initial voltage at the output is assumed to be +Vsat. This makes the threshold voltage, VT also positive and is given by:

Initially, no input is applied at the inverting terminal of the op-amp. Thus the voltage at the inverting terminal, V_=0. To change the output state from +Vsat to -Vsat a positive pulse is applied at the inverting terminal of op-amp. The magnitude of the trigger pulse should be greater than +VT to change the state of the output.

The application of a trigger pulse changes the output state from  to . In this stable state(, the threshold voltage is negative and is given by:

Further, to change the state from  to , a negative trigger is applied at the inverting terminal of the op-amp. Again, the magnitude of the trigger pulse should be greater than -VT to change the state of the output:

Waveform of a Bistable Multivibrator

Click here to learn more about Astable Multivibrator Circuit.

Click here to learn more about Monostable Multivibrator Circuit.