Fisher FX-3 Metal Detector

Fishers FX-3 Ferro Probe is a differential Induction Magnetometer designed to locate iron and steel relics, property markers, pipes and other large ferrous objects buried beyond the reach of ordinary metal detector. Two sensors respond only to the magnetic field of ferromagnetic objects, ignoring all other materials (copper, aluminum, brass, etc.). As a target is approached, the VCO (Voltage Controlled Oscillator circuitry responds with an increase in pitch and volume then nulls directly over the target.