A metal detector includes a detector head having a primary or transmit coil for the transmission of electromagnetic radiation therefrom, and having a plurality of secondary or receiving coils associated therewith for having voltages induced therein by transmissions from said primary coil. The presence...http://www.google.es/patents/US4912414?utm_source=gb-gplus-sharePatente US4912414 - Induction-type metal detector with increased scanning area capability
Induction-type metal detector with increased scanning area capability
