# Oscillators

Types of Oscillators

Types of Oscillators

**Tuned LC Oscillator :**

where, L_{1}is the inductance in Henry

C_{1}is the capacitance is Farad

f is the output frequency in Hertz

**Fig. : **Tuned LC oscillator

**Hartley Oscillator**

where L_{T}= L_{1}+ L_{2}+ 2M

The Hartley Oscillator consists of a parallel LC resonator tank circuit whose feedback is achieved by way of an inductive divider.

**Fig. : **Hartley oscillator

**Colpitt’s Oscillator**

The basic configuration of the Colpitts Oscillator resembles that of the*Hartley Oscillator*but the difference this time is that the centre tapping of the tank sub-circuit is now made at the junction of a “*capacitive voltage divider*” network instead of a tapped autotransformer type inductor as in the Hartley oscillator.

The frequency of oscillations for a Colpitts Oscillator is given as:

** **

**Fig. : **Colpitt’s oscillator

**Phase shift RC Oscillator :**

where N is the number of RC stages (N = 3)

**Fig. (d) : **Phase shift RC oscillator

**Crystal oscillator :**

Series resonant frequency

Parallel Resonant Frequency

where

**Fig. :** Crystal oscillator

**Wien Bridge Oscillator :**

or R = R_{1}= R_{2}; C = C_{1}= C_{2}

=

** **

**Fig. : **Wien bridge oscillator