Abstract: For measuring unknown capacitances, which exist in capacitive sensors, such as pressure, moisture, inclination sensors and the like, the invention proposes a capacitance measurement method, in which a capacitance to be measured is charged and discharged across a resistor and the charging or discharging time up to a preset voltage value is measured and in which the charging/discharging times of a known reference capacitance and stray capacitances are measured across a resistor. The invention also proposes a circuit for measuring an unknown capacitance to be measured and having a voltage source, a resistor for charging or discharging at least the measuring capacitor, at least one switch for connecting and disconnecting the measuring capacitor with respect to the voltage supply and a time measuring device, in which switches are provided for connecting and disconnecting the measuring capacitor and at least one reference capacitor with respect to the circuit.
Abstract: A method for the temperature compensation of a resistance measuring bridge, such as in particular a Wheatstone bridge, is characterized in that a capacitor positioned between the input circuit and a resistance switching circuit of the Wheatstone bridge is successively discharge by means of at least one Wheatstone bridge resistor. In a device for the temperature compensation of a measuring bridge, particularly a Wheatstone bridge, having a measuring bridge and a compensating resistor in the input circuit, one or two switches are located in the resistance switching circuit branch of the measuring bridge as a contact point with the latter and a capacitor is located between the input circuit and the resistance switching circuit branch.
Abstract: In order in a method for measuring the resistance across discharge times of a capacitor to eliminate the interfering influence of the resistance values of electronic switches, the invention provides for a capacitor to be repeatedly charged and discharged and the charging or discharging time is measured by means of at least one resistor (R1, R2, R3) and at least one first switch (S11, S21 or S31) connected in series therewith, at least one second switch (S12, S22 or S32) connected in series with the resistor (R1, R2 or R3) and juxtaposed, parallel-connected switches (S11, S12 or S21, S22 or S31, S32) connected in series with the resistor (R1, R2 or R3).