Are metal detectors radioactive?

As the core component of the metal detector, there are three groups of coils in the detector, namely the central transmitting coil and two equivalent receiving coils. The high-frequency variable magnetic field is generated by an oscillating drop-type metal detector oscillator with a transmitting coil connected in the middle. In the idle state, the induced voltages of the receiving coils on both sides cancel each other before the magnetic field is disturbed, thus achieving a balanced state. Once the metal impurities enter the magnetic field area, the magnetic field is disturbed, and this balance is broken, and the induced voltages of the two receiving coils cannot be offset. The control system amplifies and processes the uncompensated induced voltage and generates an alarm signal (metal impurities are detected).