Abstract: A metal detector system which includes an electromagnetic search coil, a gate for diverting portions of a material stream containing metal detected by the search coil to a reject container, and a coupling for isolating vibrations caused by the gate from the search coil. The metal detector system also includes control circuitry for automatically recycling the gate when an obstruction prevents the gate from returning to its normal standby position. A test circuit is provided to test the search coil by closing a conductive loop passing through the electromagnetic field of the search coil.