| 摘要 |
A conductivity measuring device has a current source (SQ, S1, S2, S3, S4) which can be connected to two conductor devices via which a substantially square-wave current can be fed into a liquid and a mesuring circuit (OPV, S5 - S11, CM, CR) to determine the voltage drop in the liquid between voltage measuring components. To provide such an integratable conductivity measuring device in which no polarisation effects occur, in which there is no galvanic connection to the liquid, the conductivity of which is to be measured, and which permits the simple measurement of the conductivity of the liquid, it is proposed that the measuring circuit be a switch-capacitor circuit having a measuring capacitor (C1), a differential amplifier (OPV) with a feedback capacitor (C2) in its feedback branch and a switch device (S5 to S11) by means of which (S5 to S11) the two connections of the measuring capacitor (C1) are connected dependently in time on the path of the square-wave current to the voltage electrodes (E2, E3) in one switching position and to the two inputs of the differential amplifier (OPV) in another, and that the current conducting components take the form of current coupling capacitors (CK1, CK4). |
