Diac full detail :-
Diac construction, working, characteristics, application,advantage disadvantage
Diac words are made by two words first is Di means Diode ,second is AC means alternating current. So the sum of these two words are Diac ,it stands for Diode for alternating current .
Symbol of diac :-
Construction of diac :-
1 :-The diac is important member of thyristor family and usually employed for triggering TRIAC.
2. Diac is a two electron bidirectional avalanche diode which can be switched from OFF state to ON state for either polarity of applied voltage.
3 The diac is pnpn structure type device.
4. The diac is four layer two terminal semiconductor device.
5. The switching from OFF state to ON state is achieved by exceeding the avalanche breakdown voltage in either direction.
6. This two terminal is connected by omnicontact .
How to work diac (Working):-
:- when the terminal MT2 is positive the current flow path is P1-N2-P2-N3.
:-When the terminal MT1 is positive the current flow path is P2-N2-P1-N1.
:- The operation of the DIAC can be explained by imagine that two diode connected in series.
:-When applied voltage in either polarity is a (small less than break over voltage) a very small amount of current called leakage current flow through the device.
:- Leakage current is caused due to the drift of electrons and holes in depletion region which is not sufficient to cause conducting in the device.
:- when magnitude of applied voltage is avalanche break down over voltage breakdown take place and current Rises sharply.
Characteristics of diac :-
Applications of diac :-
It is used for triggering device in TRIAC, phase control circuit,employed for lamp dimmer ,heat control ,Universal motor speed controller etc.
Advantage of diac :-
- Low cost device.
- Excellent characteristic.
- Low power consumption.
- Normal operating conditions.
Disadvantage of diac :-
- Overheating.
- We can't use in dc.
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