What is a Dynamic Microphone?
A dynamic microphone consists of a plastic diaphragm, voice coil, and a permanent magnet.
The diaphragm is connected to one end of the voice coil, while the other end of the coil is loosely supported around (or within) the magnet. When an alternating pressure is applied to the diaphragm, the voice coil alternates in response. Since the voice coil is accelerating through the magnet’s magnetic field, an induced voltage is set up across the leads of the voice coil. You can use this voltage to power a very small load, or you can use an amplifier to increase the strength of the signal so as to drive a larger load.
Dynamic microphones are extremely rugged, provide smooth and extended frequency response, do not require an external DC source to drive them, perform well over a wide range of temperatures, and have a low impedance output.
Some dynamic microphones house internal transformers within their bodies, which give them the ability to have either a high- or low-impedance output-a switch that is used to select between the two.
Dynamic microphones are widely used in public address, hi-fi, and recording applications.