Definition of Monostable Multivibrator and How It Works

Definition of Monostable Multivibrator and How It Works - Monostable Multivibrator is a type of multivibrator that has a single stable state. As the name suggests, MONO which means ONE indicates a stable state as well as a quasi-stable state. This Monostable Multivibrator is also known as a one-shot multivibrator.

Monostable Multivibrators have only ONE steady-state and produce a single output pulse when triggered externally. Monostable multivibrators only return to their original state and stable state after a period of time determined by the time constant of the RC (Coupled RC) combined circuit. Monostable Multivibrators are commonly used in applications such as television circuits and control system circuits.

Monostable Multivibrator Circuit

As shown in the picture above, two transistors, namely Q1 and Q2 are connected in feedback to each other. The collector of transistor Q1 is connected to the base of transistor Q2 through capacitor C1. The base of Q1 is connected to the collector of Q2 through resistor R2 and capacitor C. The supply voltage DC –VBB is supplied to the base of transistor Q1 through resistor R3. A trigger pulse is given to the base of Q1 via capacitor C2 to change its state. RL1 and RL2 are load resistors in Q1 and Q2.

One of the transistors, when it goes into a stable state, an external trigger pulse is given to change its state. After changing its state, the transistor remains in a quasi-stable state for a certain period of time determined by the value of the RC time constant and returns to its previous stable state.

Note: Quasi-Stable State is the Stable State of the Multivibrator at the time of operation.

Monostable Multivibrator Advantages and Disadvantages

The simple circuit design and relatively low price are the advantages of this Monostable Multivibrator. While the main disadvantage of this monostable multivibrator is the time between applications of the trigger pulse T must be greater than the RC time constant of the circuit.

Also Read : Definition of Astable Multivibrator and How It Works