A metal detector, includes a transmitter for transmitting a repeating sequence of transmit magnetic field, each of the sequence includes a period of changing or constant non-zero transmit magnetic field, immediately followed by period of rapid change of transmit magnetic field, immediately followed by a period of substantially constant or zero transmit magnetic field; a receive coil; and a damping resistor. An end of the receive coil is connected to one end of the damping resistor and the other end of the damping resistor is connectable to a circuit with a variable parameter. A signal is induced in the receive coil during the period of rapid change of transmit magnetic field, and the signal induced in the receive coil decays at least at a termination of the period of rapid change of transmit magnetic field.