Types of Oscillators

1.Sinusoidal Oscillators -  these are known as Harmonic Oscillators and are generally a "LC Tuned-feedback" or "RC tuned-feedback" type Oscillator that generates a purely sinusoidal waveform which is of constant amplitude and frequency.

 

2.Non-Sinusoidal Oscillators -  these are known as Relaxation Oscillators and generate complex non-sinusoidal waveforms that changes very quickly from one condition of stability to another such as "Square-wave", "Triangular-wave" or "Sawtoothed-wave" type waveforms

Amplitude Stabilisation

In  the oscillators below, the loop gain is set by component values

1.In practice the gain of the active components is very variable

1>.If the gain of the circuit is too high it will saturate

2> If the gain of the circuit is too low the oscillation will die

o Real circuits need some means of stabilising the magnitude of the oscillation to cope with variability in the gain of the circuit