Abstract: A metal detection apparatus that uses one or more operating frequencies. The metal detection apparatus comprises, among other things, a transmitter unit that provides transmitter signals to a transmitter coil that is coupled to a receiver coil, which is connected to the input of a receiver unit. The transmitter unit comprises a frequency generator that provides an operating frequency to the input of an amplifier stage, whose output is connected via a transformer to the transmitter coil. The amplifier stage is connected to a first tap and the transmitter coil is connected to a second tap of the same transformer winding of the transformer. A resonant circuit is formed that is tuned to the operating frequency, and can be tuned optimally and independently of other parts of the transmitter unit.

Abstract: A metal detection apparatus that uses one or more operating frequencies. The metal detection apparatus comprises, among other things, a transmitter unit that provides transmitter signals to a transmitter coil that is coupled to a receiver coil, which is connected to the input of a receiver unit. The transmitter unit comprises a frequency generator that provides an operating frequency to the input of an amplifier stage, whose output is connected via a transformer to the transmitter coil. The amplifier stage is connected to a first tap and the transmitter coil is connected to a second tap of the same transformer winding of the transformer. A resonant circuit is formed that is tuned to the operating frequency, and can be tuned optimally and independently of other parts of the transmitter unit.