METAL DETECTOR SENSOR Russian patent published in 2015 - IPC G01V3/11 

FIELD: electricity.

SUBSTANCE: sensor comprises in-series first capacitor C1 and exciting coil L1, the second signal coil L2 and second capacitor C2 connected in parallel, in-series coil L3 and capacitor C3, in-series coil L4 and capacitor C4. Free contact of the capacitor C1 is input of exciting current with the first frequency. Free contact of exciting coil L1 input of exciting current with the second frequency. The first contact of signal coil L2 is the first output of the sensor. The second contact of signal coil L2 is connected to common point of the circuit. Free contact of coil L3 is coupled to input of exciting current with the first frequency. Free contact of capacitor C3 is connected to midpoint of in-series connection of capacitor C1 and exciting coil L1. Free contact of coil L4 is connected to the first sensor output. Free contact of capacitor C4 is connected to common point of the circuit. Connection point of coil L4 and capacitor C4 is the second output of the sensor. Coils L1 and L2 are placed in the same plane and partially combined with each other with a value of combination area selected o that value of electric flux through signal coil L2 produced by exciting coil L1 is minimum.

EFFECT: improved sensitivity of the sensor.

5 cl, 2 dwg