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
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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’
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6. Characteristics
❖ Sensitivity : output is very low – built-in amplifier – output is then
about 3mV at SPL of 0.1 Pa
❖ SNR : high about 40 dB
❖ Freq Resp : excellent – 40 Hz to 15 kHz – standard microphone –
against which other microphones and loudspeakers are
tested – used in sound level meters.
❖ Distortion : low – about 1%
❖ Directivity : Omni-directional
❖ Output Imp : High – about 100 MΩ
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7. Applications
❖ used as standard mic – for calibrating other mic
❖ used in sound level meters
❖ used in professional hi-fi systems
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