KRETS FOR METNING AV KAPACITANSSKILLNADEN MELLAN TVA KONDENSATORER

摘要

An improved capacitive pick-off circuit is provided by utilizing an operational amplifier wherein a pick-off capacitor to be measured forms a part of a feedback circuit of the operational amplifier resulting in the gain of the operational amplifier becoming inversely proportional to the capacitance or directly proportional to the gap between the plates of the capacitor thereby providing a measure of capacitance. A differential capacitive pick-off circuit is implemented by using a pair of operational amplifiers wherein feedback circuits controlling the gain of the operational amplifiers include pick-off capacitors to be measured and a third differential amplifier is connected to the outputs of the two operational amplifiers to provide a signal representing the difference in capacitance between the two pick-off capacitors.