capacitve sensor basic principle

Capacitive Sensors fundamentals

Capacitance is ordinarily estimated in a roundabout way, by utilizing it to control the recurrence of an oscillator, or to differ the degree of coupling (or weakening) of an AC signal.

The structure of a straightforward capacitance meter is frequently founded on an unwinding oscillator. The capacitance to be detected structures a bit of the oscillator's RC circuit or LC circuit. Fundamentally the system works by accusing the obscure capacitance of a known current.

Capacitance equation,

C= Ak/d.

C= Ak/d

Where, C = capacitance (Farads)

k = dielectric constant

A = area of plates

d = distance between plates (electrodes)

The capacitance can be determined by estimating the charging time required to arrive at the edge voltage (of the unwinding oscillator), or equally, by estimating the oscillator's recurrence. Both of these are corresponding to the RC (or LC) time steady of the oscillator circuit. A shown in figure capacitance will change as per the dielectric constant change.