Condenser Microphone
Print Overview
A condenser microphone incorporates a stretched metal diaphragm that forms one plate of a capacitor. A metal disk placed close to the diaphragm acts as a backplate. When a sound field excites the diaphragm, the capacitance between the two plates varies according to the variation in the sound pressure. A stable DC voltage is applied to the plates through a high resistance to keep electrical charges on the plate. The change in the capacitance generates an AC output proportional to the sound pressure. In order to convert ultralow-frequency pressure variations, a high-frequency voltage (carrier) is applied across the plates. The output signal is the modulated carrier.
Condenser microphone. AP = acoustic pressure, C = variable capacitance, 1 = metal diaphragm, 2 = metal disk, 3 = insulator, 4 = case.
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