The locally mounted oscillator drives the guard at 16kHz at a constant amplitude. This induces an identical sinusoidal oscillation on the centre wire and hence the electrode. As a target comes into the sensor tip’s range the additional capacitance coupled between the sensor tip and target modifies the electric field.
This causes a reduction in the amplitude of oscillation of the centre wire/electrode. Output from the oscillator is a reference oscillation which, when compared with the signal oscillation, gives a difference proportional to the capacitance at the sensor tip.
The oscillator also contains a differential amplifier into which both the signal oscillation and reference oscillation are fed. The output from […]
Read more
