A signal transmitter system (10) for an animal training system including an electrical impedance loop (12), a signal generator (24) and a power supply (22). The signal generator (24) is connected to the electrical impedance loop (12). The signal generator (24) provides a current signal to the electrical impedance loop (12). The power supply (22) provides a voltage level to the signal generator (24). The voltage level is dependent upon a measured characteristic of a voltage signal that results from an interaction of the current signal with the electrical impedance loop.