The moving coil type words are made using electromagnetic induction. The moving coil type words simply have a diaphragm with a coil and a permanent magnet. When the sound wave impacts the diaphragm, the coil connected to the diaphragm is in the magnetic field of the permanent magnet. Cutting the magnetic lines of force produces audio-frequency induced current, so the moving coil type is characterized by: magnets, coils, and diaphragms. (The feeding of moving coil types generally requires a step-up transformer, so) its volume and weight are relatively large. Capacitive talks are big, KTV talks and those on the rostrum at large gatherings are mostly moving-coil talks;
The capacitive type is to change the position of the capacitor plate according to the size of the sound, so that the capacitance changes with the size of the sound, thereby outputting audio current signals. The capacitive type is small in size and light in weight, just like the one installed in the phone.
The advantages of dynamic microphones are simple structure, low price, stable work, sturdiness and durability, and long life. The diaphragm of dynamic microphone (equivalent to our eardrum) is located in the annular gap between a cylindrical magnet and a piece of soft iron. A movable coil suspended between two magnetic poles is connected to the diaphragm. This coil is usually called a "voice coil". The sound wave vibrates the diaphragm, causing the voice coil to cut the magnetic lines of force in the circular gap during movement, thereby inducing current and outputting.
The advantages of condenser microphones are low noise, low distortion, high sensitivity, and a wide frequency response, up to 20Hz～20kHz or wider. It has good directivity and can meet the needs of most indoor and outdoor pickups. The disadvantage is that the ambient sound field easily affects the pickup effect. The full name of condenser microphone is "capacitance variable microphone". It consists of a metal vibrating membrane and a fixed electrode. The distance between the two is very close, about 0.025 to 0.05 mm. The medium in the middle is air, thus forming a capacitor. This capacitor is generally called a pole. When a polarizing voltage is applied to the pole, a charge will be generated on the two poles. Sound waves vibrate the diaphragm, the charge will change, and finally a voltage is generated across the load resistance to form an audio signal.