What is an Electret Microphone? How does it work?

What is an Electret Microphone? How does it work?

It is a type of microphone that converts sound waves into electrical signals. There are some important differences from other types of microphones, especially when compared to dynamic microphones. Basic information about what electret microphones are and how they differ from other types of microphones:

Working Principle of Electret Microphone:

electret Microphone pins

Electret microphones work using a capacitive transducer. The electret material inside them (an insulating material called a permanent electret) is polarized, and this polarization provides a constant electrical charge necessary for the microphone to operate. When sound waves hit the electret surface, this electrical charge changes, and this change is seen as a voltage change at the output of the microphone.

Comparison with Dynamic Microphones:

Dynamic microphones work on the principle of electromagnetic induction. A moving coil in a magnetic field responds to sound waves, and the movement of this coil is converted into an electrical signal at the output of the microphone.

Electret microphones are more sensitive and better at capturing low sound levels than dynamic microphones. For this reason, electret microphones are often preferred for studio recordings, radio broadcasts and similar applications.

Dynamic microphones can be more durable and can withstand high sound levels, so they are more commonly used at live concerts and in environments with high sound pressures.

Power Requirement:

Electret microphones generally do not require a battery or external power source. The electret material itself provides a constant charge necessary for the microphone to operate.

Dynamic microphones can operate without needing an external power source.

Example cirduit with Electret Microphone:

circuit with electret microphone

Size and Design:
Electret microphones can often be smaller and lighter, so they are easier to carry and use.
Dynamic microphones can be larger and heavier.

Electret microphones are microphones with more sensitive and generally smaller designs than dynamic microphones. Therefore, they can be preferred if sound quality and portability are important. However, both types of microphones have their advantages and uses, so which type to use depends on the application and requirements.

Application examples with Electret Microphone:

Microphone, Vu meter App 

Single Transistor FM Transmitter Circuit