MEASURING AND LINEARIZING CIRCUIT DEVICE FOR A CAPACITIVE PRIMARY ELEMENT

摘要

ABSTRACT OF THE DISCLOSUREA humidity sensor operates with a capacitivesensor element (CS) which is arranged in one branch ofa free-running multivibrator (MV), whereas a referencecapacitor (Cref) is arranged in the other branch ofsaid multivibrator. Both output signals (U1, U2) of saidmultivibrator (MV) are averaged by means of RC elements(R3, C1; R4, C2) and supplied to a differential amplifier(DV), the output signal (Ua) of which changes the operatingvoltage (UB) of the multivibrator (MV), and therefore,linearizes the characteristic of the capacitive sensorelement (CS).