condenser microphone pdf

                                 Condenser microphone

when the sound wave strike the diaphragm it moves compression increases capacitance and rarefaction decreases in capacitance change in capacitor results in change in voltage since, charge on capacitance remain same.

                                 V = Q  /  C             ........1 equation

              

                           C =  kA / D   ............2 equation

( k = dielectric constant)

( A = area of capacitor )

( D = width of two plates )

( Q = charge held by capacitor )

                                      equation 2 value put the equation 1.

                                                     V = QD / kA

Q, k, A are constant for capacitor microphone then , Q / kA = K

                  then , V = K

 Differentiating     ds V  = K  ds  D

Thus, variation in output voltage depend on charge in distance between the plates which entered depends on the pressure variation due to sound wave.

Characteristics 

* distortion is low , about 1%.

* omnidirectional.

* output impedance is very high, about 100 ohm,s.

* signal to noise ratio is high , about 10dB.

* very good frequency response  from 40hz to 15khz.

* sensitivity is low therefore it has in built amplifier .

Application

* used as standard microphone for calibrating  other microphone.

* used in sound level meters.

* used in professional high fidelity recording.

condenser  micro