a function of time when rectifier 16 is in the full wave rectification mode amplifier 28 delivers energy in pulses during both half wave segments of the alternating current waveform when rectifier 16 is in the half wave mode amplifier 28 delivers energy in only every other half wave segment the energy delivered through amplifier 28 to rectifier 16 is sensed by current sensing resistor 34 and decoder 36 exemplary current waveforms are illustrated in fig2 a and 2b representing the full wave and half wave modes respectively it will be seen that the current flowing through resistor 34 comprises two current pulses per cycle when full wave rectification is in effect and comprises one pulse per cycle when half wave rectification is in effect this difference in the number of current pulses per cycle is detected by decoder 36 as a representation of the rectifier mode at any given point in time since the rectifier mode is controlled by the data in signal applied to encoder 18 decoder 36 provides a data out signal which is the binary equivalent of the input data in signal in this fashion the implanted device can convey signals to the external device for providing a readout.