A multivibrator is a circuit that has two stable states. Each stable state is represented by a voltage e.g 0Volts and 5 volts. The astable variety is when the output. Astable and Monostable Multivibrator Using Timer IC modes: Astable, Monostable and Bistable IC as an astable multivibrator is a. The name mutivibrator designates a group of the circuits widely applied for switching as shift registers or temporary memories and as square.
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A multivibrator is basically a two stage RC coupled amplifier with positive feedback from output of one amplifier to the input of the another amplifier. This is shown in the figure It is basically a switching circuit which generates non-sinusoidal waves such as square, sawtooth and rectangular etc.
Multivibrator circuits are widely used in storing numbers, counting of pulses, synchronization of arithmetic operations and so on. Depending upon type of coupling network used, there are three types of multivibrators. Figure-2 depicts circuit used for astable multivibrator.
Multivibrator – Wikipedia
In this configuration, both coupling networks provide AC coupling through coupling capacitors. Each amplifier stage provides phase shift of degree in midband.
This results into positive feedback due to overall phase shift of degree or 0 degree. It has no stable state.
Figure-3 depicts circuit used for monostable multivibrator. In this configuration, one coupling network provides AC coupling while the other provides DC coupling. The circuit has one stable state and one quasi stable state.
In this circuit, a triggering signal is required to induce transition from stable to quasi stable state. Since the circuit vibrates once for a trigger, it is called a uni-vibrator or monostable multivibrator. Figure-4 depicts circuit used for bistable multivibrator.
This configuration requires application of two triggers to return the circuit to its original state. The first trigger causes conducting transistor to cut-off astablr and second trigger causes it back to conducting mode. This circuit does not oscillate. In this circuit, both coupling networks provide DC coupling and no energy storage element is used.
Monostable Multivibrator Figure-3 depicts circuit used for monostable multivibrator. Bistable Multivibrator Figure-4 depicts circuit used for bistable multivibrator.