2. Contents Introduction History Astable multivibrator Operation
Multivibrator period
Monostable multivibrator circuit
Bistable mutlivibrator circuit
Application
Reference

3. Introduction
A multivibrators is a basically a two stage R-C coupled amplifier with positive feedback from the output of one amplifier to the input of the other.
As shown in figure-
Multivibrators is a switching ckt and may be define
as an electronic ckt that generates non sinusoidal
wave such as rectangular waves,sawtooth waves square waves.

4. Basic configuration of a multivibrator

5. History
The classic multivibrator circuit is first described by H Abraham at 1919.The multivibrator also called a ‘Plate-coupled multivibrator’.
Types of multivibrator circuits- Depending upon coupling n/w-
Astable multivibrator
Bistable multivibrator.
Monostable multivibrator.

6. Astable multivibrator
In an astable multivibrator,both coupling network provide AC coupling capacitor.
The astable multivibrator is also called ‘Free-running multivibrator& collector-coupled astable multivibrator.
The circuit of an astable multivibrator using to similar transmission is depicted in fig:

7. Fig:BJT astable multivibrator

8. Waveform of astable multivibrator

9. Operation:
The circuit operation is based on the fact that the forward-biased base emitter junction of the switched-on BJT can provide a path for the capacitor restoration.
The circuit has two stable state Q1 is switched on,Q2 is switched off,
-Q1 is switched off,Q2 is switched on.

10. Monostable multivibrator
Monostable multivibrator is a two-stage amplifier with two states-one stable state & another quasi state.
The MMV generates one output pulse for every trigger pules so it is also called single-shot multivibrator.
fig: shows the circuit of a MMV-

11. BJT monostable multivibrator

12. Waveform of monostable multivibrator

13. Bistable multivibrator circuit
In the bastable multivibrator,both resistive-capacitive n/w are replace by resistive networks.
The bistable multivibrator,also called a two-shot multivibrator,requires application of two trigger
to return the ckt to its original state.
Because two triggers are required .bistable ckt are sometimes called flip-flops.
fig-show the bistable multivibrator ckt :

14. Bistable multivibrator circuit

15. Application In astable multivibrator- Frequency adjustment is easy.
Synchronization is easy.
In monostable multivibrator-
It can be employed to generate
new pulse.
In bistable multivibrator-
As frequency divider
Binary information.

16. References
^ Multivibrator in IEEE Std. 100 Dictionary of Standards Terms 7th ed.,IEEE Press, 2000 ISBN page 718
^ William Henry Eccles and Frank Wilfred Jordan, "Improvements in ionic relays" British patent number: GB (filed: 21 June 1918; published: 5 August 1920).
^ a b Donald Fink (ed), Electronics Engineers' Handbook, McGraw Hill, 1975 ISBN , page 16-40

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