Industrial metal detectors and hobby detectors were developed by the military to detect mines and other metal objects. Although there are many kinds of metal detectors in the marketplace, most detectors in use today, are variations of two types. One type is known as balanced coil and the other is known as pulsed eddy current. Balanced coil detectors set up an energy field that is energized continuously. As metal interrupts this field, the phase of the energy field is shifted. These style metal detectors can be found in hobbyist applications at one extreme to very sophisticated detectors used in food and bulk powder markets.

PJ TECH detectors are of the second, "pulsed eddy current" type. The transmission of energy is pulsed and the energy field is created and collapsed in a cyclic manner. These detectors are not susceptible to false tripping due to changes in product properties, known as "product effect". An example of product effect is conductivity, which often changes with changes in moisture content.


Metal Detection > Introduction / Technology & History