Crystal microphone

A crystal microphone is based on the principle of piezoelectric effect. when the sound wave strike on the  diaphragm

it  vibrates and compress the crystal. In case o rarefaction converse take place and crystal is standard and is under tension due to this compression and rarefaction. a varying potential difference is generated which is proportional to the applied mechanical  pressure by sound wave the  crystal elements are connected in such a way that the  potential difference developed elements are added up and get good output voltage.

Characteristics

* distortion is low , about 1%.

* omnidirectional.

* output impedance is very high , about 1Mohm.

* signal to noise ratio , about 40dB.

* flat  frequency response from 80 to 

   8khz.

* sensitivity is good , about 50 mv for sound pressure of 0.1 pa.

 

 Application

* used for recording system.

* used for mobile communication.