# How Oscillator Works? The Working Principle of the Oscillator Explained

This video will be helpful to all the students of science and engineering in understanding the working principle of the oscillator.

By watching this video, you will learn the following topics:

0:42 What is Oscillator

1:04 How OScillator Works?

4:03 Barkhausen Criteria for Oscillations and mathematical derivation

8:12 Different Types of Oscillators

What is Oscillator:

The Oscillator is an electronic circuit, which accepts the DC voltage and generates the periodic time varying waveform of the desired frequency.

How Oscillator Works:

The Oscillator is an amplifier with positive feedback. When the Oscillator is turned ON, then the thermal noise is amplified by the amplifier of the oscillator. The feedback circuit in the oscillator is the frequency selective circuit. It amplifies only one particular frequency from all other frequencies. And over the period of time, the one frequency will get build up and gives the periodic oscillations at the output.

Barkhausen Criteria:
For sustained Oscillation,
1) the magnitude of the loop gain AB should be equal to 1 (AB =1)
2) Phase Shift introduced by the amplifier and the feedback circuit should be zero.

Types of OScillator:
Depending on the type of feedback circuit the oscillators can be broadly classified as
1) RC OScillator
2) LC OScillator
3) Crystal OScillator

Depending on the arrangement of these R, L, C components, it can be further classified. (Colpitts Oscillator, Hartley Oscillator etc.)

Depending on the type of output, the oscillators can be classified as
1) Harmonic Oscillators (Gives Sinusoidal Output)
2) Relaxation OScillators (Gives Non-Sinusoidal Output, Like square wave and Triangular Wave)