Inductive proximity sensors

Inductive proximity sensors consist of an electrical resonant circuit (1), a flip-flop (2) and an amplifier (3) (cf. Figure 4.3). When voltage is applied to the connections, the resonant circuit generates a (high-frequency) magnetic alternating field that escapes from the front side of the sensor. Bringing an electrical conductor into this alternating field "attenuates" the resonant circuit. The downstream electronic unit, consisting of a flip-flop and amplifier, evaluates the resonant circuit's behaviour and actuates the output.

Inductive proximity sensors can be used to detect all materials with good electrical conductivity, for example graphite as well as metals.