The metal detector is used to detect metal foreign objects mixed in the production process of food, medicine, cosmetics, textiles, etc.
The principle is a central transmitting coil and two equal receiving coils, and these three coils are installed in a detector head. The oscillator emits a high-frequency magnetic field through the transmitting coil in the middle, which is connected to the two receiving coils, but with opposite polarities. When the magnetic field is not disturbed by the outside world, the voltage output signals generated by them cancel each other out. Once the metal impurities enter the magnetic field area, this balance will be destroyed, and the induced voltages of the two receiving coils cannot be canceled. Alarm signal (metal impurities detected). The system can use the alarm signal to drive the automatic rejection device, so as to remove the metal impurities from the production line.