| 摘要 |
The invention concerns improvements in a capacitor type microphone, comprising a printed circuit board having an aperture therethrough at one end thereof, a fixed but spacially adjustable plate member mounted in said aperture, a plastic membrane coated on one side with a magnetic conductive material stretched across said aperture, a magnet mounted adjacent said membrane and adjustable relative thereto for attracting the membrane thereto, means for directing sound waves through said aperture against said membrane to variably displace said membrane relative to said fixed plate, a tank circuit including an inductance and said capacitor formed by said membrane and said fixed plate having its resonant frequency varied in response to the displacement of said membrane, a frequency generating circuitry for feeding energy to said tank circuit and an output means for coupling the variable frequency output from said tank circuit to a point of utilization.
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