From the outside, an electret microphone typically has a few visible components:
- Protective Mesh or Dust Cover: This is the outermost layer, designed to protect the microphone’s internal components from dust and debris.
- Aluminum Housing: The metallic outer shell that encases the microphone’s internal components, providing structural support and electromagnetic shielding.
- PCB (Printed Circuit Board): Visible at the base or side, this is where the microphone’s electrical connections and some components, like the Field Effect Transistor (FET), are located.
Within the aluminum housing, the microphone is composed of several critical internal components:
- Diafragma: Located just beneath the dust cover, this thin membrane vibrates in response to sound waves. It is the primary component that converts acoustic energy into electrical signals.
- Espaciador aislante: Positioned between the diaphragm and the backplate, this component electrically insulates the diaphragm from the rest of the microphone, preventing short circuits.
- Non-metallic Frame: This internal support structure holds the diaphragm, backplate, and other components in place, ensuring their proper alignment and spacing.
- Backplate and FET (Field Effect Transistor): The backplate, together with the diaphragm, forms the capacitor that is fundamental to the electret microphone’s operation. The FET, often attached to the PCB, amplifies the weak electrical signal generated by the diaphragm’s vibrations.
In summary, the aluminum housing encloses and protects the diaphragm, insulating spacer, non-metallic frame, backplate, and FET, all of which work together to convert sound into an electrical signal.