Type of microphone

* moving coil microphone.

* crystal microphone.

* ribbon microphone.

* carbon granule microphone.

* elctret microphone.

* wireless or cordless microphone.

* telescopes or gun microphone.

Ribbon microphone

In this type of microphone carbon granules are packed in the casing and the resistance of carbon granules depend on applied pressure. when the sound wave strike on the diaphragm then the diaphragm vibrates as a result there is a compression or rarefaction in the carbon granules. when the carbon granules a compressed there resistance decreases, when the carbon granules loosen their resistance increase. this change in resistance of carbon granules changes the current in the circuit. this change in current causes a change in terminal voltage.

   Characteristics of carbon granule

* sensitivity is very high , about 20dB .

* signal to noise ratio is poor.

* distortion is high ,about 10%.

* output impedance is ,about 100 Ohm,s.

* omnidirectional.* frequency of 200HZ to 5kHZ.

Application 

* due to limited frequency range it is used in telephone.

* radio communication set .