| 摘要 |
A measuring instrument has a measuring configuration and a measuring circuit. The measuring circuit determines the capacitance of a capacitor and the conductance of the measuring configuration, which is formed of a casing and a sensor element around which a mixture flows. The alcohol content of the mixture is determined therefrom. The measuring circuit has an oscillator and a control circuit connected upstream thereof. The measuring configuration, which is represented by the capacitor and the conductance, is a part of the oscillator, which oscillates within a measuring cycle at three different oscillator frequencies which are set by three different control voltages of the control circuit, and evaluated in a microcontroller. Component tolerances which influence the oscillator frequencies can thus be taken into account. |
