Mumbai University > COMPS > Sem 3 > Digital Logic Design and Analysis

Marks: 7 M

Year: May 2015

Multivibrator:

• A multivibrator is a electronic circuit used to implement a variety of simple two stage system such as :

  a) Oscillators

  b) Timers and

  c) Flip- Flop

• It is characterized by two amplifying devices (transistors, electronic tubes, and other services) cross coupled by resistors or capacitors.

• Complex circuit such as shift registers, counters, latches, and memories require clock pulses or timing signal to cause to change their state.
• Clock pulses are generally continuous square or rectangular shaped waveform that Is produced by single pulse generator circuit such as multivibrator.
• A multi vibrator circuit oscillates between ‘HIGH’ or ‘LOW’ state providing a continuous output.
• There are basically 3 types of clock pulse generation circuit (multivibrator)

1. Stable :

   • A free running multivibrator that has NO stable state but switches continuously between the two states this action produces a train of square wave pulse at a fixed frequency.

2. Monostable :

   • A one shot multivibrator that has only one stable state and is triggered externally with it returning back to its first stable state

3. Bistable :

   • A flip flop that has two stable state that produces a single pulse with either positive or negative in values.

   Following figure shows Multi-vibrator Circuit

$$\text{Multivibrator circuit}$$