Question

Explain the working of transistor as an oscillator

Answer 1

Working of Transistor as an oscillator and amplifier. Since a transistor mainly transfers the resistance, it is called as transistor. There exists an input circuit with a small source of power and a small resistance and an output circuit with a high resistance and moderately large source of power.

Answer 2

A transistor which is fed with positive feedback (ie. Both input and output are in phase) can act as an oscillator.

Oscillator acts as generator which produces sine waveform without any input signal.

Condition for oscillations :

For the oscillator, we want that the feedback to drive the amplitude and hence Vf(feedback voltage) must act as Vi(input voltage)

1. |Aβ| =1
2. Total phase shift around a loop is 360°. ie, 180° is introduced by inverting amplifier and 180° is introduced by feedback network.

The two conditions above are required for the circuit to work as an oscillator, and these are called the Barkhausen criterion for oscillations and produce sustained oscillations of constant frequency.

Hope this helps you!