An implanted medical apparatus and external power source use the same coilsfor energy transfer to the implanted medical device as used for transmissionof control signals from the implanted device. In one example, implantedcircuitry generates a feedback control signal indicative of the load voltagelevel of a load-generating medical device and superimposes the feedback signalon an inductor capacitor (LC) tank circuit for detection by the externalpowering apparatus. The external powering apparatus uses the feedback signalto control the energy transfer to the implanted medical device, thusregulating the load voltage at the load-generating medical device
