Condenser Microphone

Condenser Microphone

1. Capacitor/Condenser
Microphone

By Prof. Hitesh Dholakiya

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2. Outlines
“* Basics of Condenser Microphone
« Structure of Condenser Microphone
« Working of Condenser Microphone
** Characteristics of Condenser Microphone
< Applications of Condenser Microphone

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3. Basics

«< When capacitance changes, the charge on the capacitor tends to
remain the same, and hence voltage changes in accordance with
V=Q/C.

+ If C increases, V will decrease and vice versa.

“+ Plates are near each other and form a capacitance of a few
microfarads.

+ Fixed DC voltage of about 50 to 100 volt is applied between plates.

+ Plates are insulated from each other.

“ Capacitance of this microphone is about 30 pF.

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4. Structure of Condenser Microphone

Metal back
plate

"Supporting

fixtures

Insulator = .
67 Voltage input

5. Working

«< Diaphragm acts as one plate of capacitor. The other
plate - Back Plate - is fixed.

“+ Sound Pressure - moves the diaphragm in - C increases
| moves out - C decreases

*% Change in C - Change in V

‘Pressure Microphone’

6. Characteristics

+ Sensitivity

“ SNR
“ Freq Resp

+ Distortion
< Directivity

< Output Imp

: output is very low — built-in amplifier — output is then
about 3mV at SPL of 0.1 Pa

: high about 40 dB

: excellent — 40 Hz to 15 kHz - standard microphone —
against which other microphones and loudspeakers are
tested — used in sound level meters.

: low - about 1%

: Omni-directional

: High - about 100 MO

7. Applications
+ used as standard mic - for calibrating other mic
“ used in sound level meters

“+ used in professional hi-fi systems