What Is an Oscillator?

Electronics is all about signals. A signal is something that carries information.

For a signal to carry information, it typically needs to vary over time. Time-varying signals are an important part of electronics.

Some basic types of signals are square wave, sine wave, triangle wave and exponential wave.

The most interesting of all these signals is the sine wave signal. This is because different sine wave signals can be combined to produce all other types of signals. So we can say that sine wave signals are a kind of building block for all other signals.

To oscillate means to move back and forth continuously between two points. A sine wave signal also oscillates continuously between its maximum and minimum value.

In digital electronics applications, signals of different frequencies are needed for different applications. The clock signal is also an oscillating signal with a specific frequency.

Figure 1. Sine wave graph

An oscillator is an electronic circuit or device that can convert a steady-state signal into an oscillating signal (sine wave signal). Oscillators are used to generate repetitive electronic signals. An oscillator can convert a steady-state DC signal into a periodic AC signal at a desired frequency.

An inverter, which generates AC power from a DC source, is also a type of oscillator.

Figure 2. Oscillator circuit

This circuit is called a phase shift oscillator. Only three types of components are needed to make this oscillator: amplifier, resistor and capacitor. When this circuit is turned on (connected to an energy source such as a battery), the output is a sine wave whose amplitude and wavelength are determined by the amplifier, resistor and capacitors.

There are many other oscillator circuits, each with its own advantages and disadvantages.

Oscillators are widely used in quartz watches, audio and video systems, computers, animated lights, radio, TV and other communication devices.