Draw the characteristics of UJT and state its working principle.

Draw the characteristics of UJT and state its working principle.
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1 Answer

Answer :

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The characteristics of Unijunction Transistor (UJT) can be explained by three parameters:

* Cutoff Region

* Negative Resistance Region

* Saturation Region

Cutoff Region : The region, to the left of peak- point, is called cut-off-point region. In the region, the emitter voltage is below the peak –point voltage (Vp). And the emitter current is approximately zero. The UJT is in its OFF position in this region. 

Negative Resistance Region : The region, between the peak point and valley point, is called negative resistance region. In this region, the emitter voltage decreases from Vp to Vv and the emitter current increases from Ip to Iv . The increase in emitter current is due to the decrease in resistance.

Saturation Region : The region, beyond the valley point, is called saturation point. In this region, the device is in its ON position. The emitter voltage VE remains almost constant with the increasing emitter current.

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