ELECTROSTATIC MICROPHONE Russian patent published in 1998 - IPC

FIELD: pressure sensors for various automatic process-control devices. SUBSTANCE: microphone has two DC voltage supplies feeding two field-effect transistors through limiting resistors connected in parallel with pressure-sensing capacitors. Sources of field-effect transistors are interconnected and connected in parallel with series circuit set up of passive inductance coil and capacitor. Pressure acting on pressure-sensing capacitors changes its value resulting in variation in capacitive component of impedance at drain-drain terminals of field-effect transistors which, in its turn, changes resonant frequency of oscillatory circuit. EFFECT: improved design. 1 dwg