METAL DETECTOR Russian patent published in 2015 - IPC G01V3/10 

FIELD: electricity.

SUBSTANCE: metal detector comprises a metal detecting sensor consisting of the first capacitor C1 and an exciting coil L1 connected in-series, the second signal coil L2 and the second capacitor C2 connected in parallel, the free contact of the capacitor C1 is an input of excitation current with the first frequency, the first contact of the signal coil L2 is the first output of the sensor, the second contact of the signal coil L2 is connected to a common point of the circuit, the exciting coil L1 and the signal coil L2 are placed in the same plane and are superimposed to each other to the value of a superimposition area selected so that the value of electric flux through the signal coil L2 produced by the exciting coil L1 is minimum; the sensor is complete additionally with the coil L3 and the capacitor C3 connected in-series. The free contact of the coil L3 is connected to the input of excitation current with the first frequency, the free contact of the capacitor C3 is connected to the midpoint of the serial connection of the capacitor C1 and the exciting coil L1; the sensor is also complete additionally with the coil L4 and the capacitor C4 connected in-series. The free contact of the coil L4 is connected to the first output of the sensor, the free contact of the capacitor C4 is connected to the common point of the circuit, the sensor is complete with the second output of the sensor, which is the midpoint of the serial connection of the coil L4 and the capacitor C4, the sensor is also complete with the input of excitation current of the second frequency, which is the free contact of the exciting coil L1.

EFFECT: increased sensitivity of the metal detector at simultaneous operation at different frequencies.

6 cl, 2 dwg