An oscillator is basically used to generate signals
One of the most common examples of oscillators is pendulum of a clock. Whenever a pendulum is pushed back, it starts swinging and oscillating at a certain frequency. In addition to this, the length of the pendulum also determines the frequency of an oscillator.
Oscillator uses energy to move back and forth. For instance, in a pendulum, potential energy gets converted into kinetic energy which results in oscillations. In due course, friction leads any physical oscillator to stop moving. To keep pendulum moving, it is required to add energy at intervals. Even, an electronic oscillator works on a same principle.
The short description of some types of oscillators is given below:
RC and LC clock oscillators: This type of oscillators produces square wave signals. They are usually used in digital electronics circuit. The commonest types of clock oscillator are resistor capacitor (RC) and inductor capacitor (LC) oscillators.
Crystal oscillators: The determining principle in this type of oscillator is quartz crystal. These oscillators are primarily used where accuracy and stability is a primary concern. Quartz crystals are extremely stable in terms of frequency. Thermal compensation can be applied to crystal oscillators to enhance its thermal stability.
Sine wave oscillators: Sine wave oscillators are used in measurement applications, for audio signal generation and reference signals in different applications etc.