The value of capacitance is determined by:

(a) the area of the plates

(b) the distance between the plates

(c) the type of dielectric between the plates

The picture above shows how the area of the plates can be adjusted by varying the overlap.


In the above diagram the flexible diaphragm act as one of the capacitor plates.

As pressure is applied to the input it bends towards the fixed plate thus increasing the capacitance.

In the above capacitor the position of the dielectric is varied to vary the capacitance.

The picture below shows an application of this.

The last diagram shows an application for capacitive transducers.

The frequency of the oscillator is determined by the LC combination.

The output of the oscillator is converted to a DC voltage.

The value of the voltage can be displayed on a digital meter as inches.

Copyright Graham Knott 2004