Home > Circuit Bricks > Electret Microphone
UPDATED:.21:05 21 October 2013


  • This is a transducer that converts sound waves into an electrical signal.
  • The output is usually very low voltage, around 5 to 10mV.
  • An electret type needs a simple supply to make it operate.
There are 2 ways circuits you can use - depending on the voltage supply. The output is via a capacitor which effectively blocks any DC voltage bias from the output.


Circuit Diagrams
An output voltage is proportional to the amount of sound that it picks up.

The output is an A.C. signal of between 5-10mV. In most cases the output will need to be connected to an Audio Amplifier to boost the signal to a useable level.

Low voltage circuit

General circuit

This version needs only 2 other components, one for the supply and another to decouple the output signal. This version provides a much more stable output and is advisable in higher voltage circuits.

The microphone is fairly small. It has 2 solder pad connections on the underside. One of them is connected to the case. This connection is the 0v connection.

Sometimes there are wires already attached to the solder pads.

Written by Phil Townshend - 2008
www.edutek.ltd.uk - Working Electronics For Students & Teachers