A metal detector apparatus including a transmit coil which transmits a magnetic field, transmit timing control circuitry which also includes timing for a semiconductor switch, and receive signal circuitry and receive signal processing circuitry, with a transmit coil damping network including at least one resistor connected in series with the semiconductor switch across the transmit coil, and timing control circuitry which generates a timing sequence which is selected so that for at least some of the time no transmit field is generated and at least during part of the transmit signal, the first semiconductor switch is controlled to be off and is turned on before the cessation of the transmit field.