Output devices allow a system to present information back into the ‘real’ world. Examples can be seen everywhere, from car indicators to doorbell buzzers or information displays.

Purpose of output devices

Output devices take the signal from the process device of a system and turn it back into a physical or ‘real-world’ signal, such as light or sound.

Light outputs

Light can be created using lamps:

The standard electrical symbol for a lamp alongside a photographs of a small indicator light bulb and an incandescent light bulb.Lamp - Used on control panels as an indicator or to provide illumination

Sound outputs

Sound can be produced using buzzers or speakers.


  • buzzers have an oscillator inside a plastic case
  • when current flows through them they produce a buzzing sound, often around 400 Hertz (Hz) in frequency depending on the type of buzzer used
  • examples of their use include in doorbells and alarms


The standard electrical symbol for a buzzer alongside a photograph of a buzzer component and connection wires.

Buzzer - Used to generate a warning sound


Name a suitable output device for an MP3 amplifier system.


Move on to Video