Tag Multivibrators

In a monostable multivibrator, one of the state is absolutely permanent i.e, stable and the other one is temporary i.e, quasi-stable.

The bistable multivibrator has two absolutely stable states. It will remain in whichever state it happens to be until a trigger pulse causes it to switch to the other state.

A multivibrator which generates square waves of its own (i.e without any external trigger pulse) is known as astable multivibrator. It is also called free ramming multivibrator.

A 555 timer IC is used a a-stable multivibrator as shown in the given figure (A). The threshold input is now connected to the trigger input (Pin 2), the resister R1, R2 and capacitor C1 for timing network which set the frequency of the oscillator.