DEVICE MEASURING ELECTRIC CAPACITANCE Russian patent published in 2002 - IPC

FIELD: measurement technology. SUBSTANCE: device is intended for precision measurement of electric capacitance. Device comprises measuring transformer bridge 1, frequency-controlled generator 2 which first output is connected to middle point of primary winding of differential transformer of measuring transformer bridge 1, synchronous detector 3 of key signal whose first input is electrically coupled to output of measuring transformer bridge 1 whose second input is coupled to second output of frequency-controlled generator 2 and whose output is coupled through filter 5 and scaling amplifier 6 of key signal to unbalance indicator of measuring transformer bridge 1 connected in series. Phase automatic tuning of frequency of generator 2 to resonance frequency of measuring transformer bridge 1 is carried out thanks to connection of second output of generator 2 to synchronous detector 3 by means of phase inverter 4 connected in series. Third output of generator 2 is connected to first input of phase manipulator 8 one output of which is connected to first input of phase detector 9 and another output of which is connected via coupling element 12 connected in series to output of measuring transformer bridge 1 connected to input of amplifier-limiter 11. Output of the latter is connected to second input of phase detector 9. Output of phase detector 9 of key signal is connected through filter 10 to frequency controlling input of generator 2 and fourth output of generator 2 is connected to input of manipulation signal generator 7 which output is connected to second input of phase manipulator 8. EFFECT: raised measurement precision. 1 cl, 1 dwg