I'm trying to design a system that will source DC power while transmitting a high impedance sourced AC signal superimposed onto this power signal. I'm sure this has been done in many applications, but I'm new to it. Currently I'm trying to use a basic adder circuit with an opamp to superimpose the two signals, but my concerns are that the DC load (a simple resistor + LED) off of the output of the opamp will load down my AC signal on the receiving circuit. I need a way to separate the two signals transparently ie not distorting the AC signal AND not excessively dissipating the DC power where its not needed. First is there a simpler or more ideal way to superimpose the two signals? Second, is there any suggestions on how to extract the AC signal off of the DC power signal without wasting power or distorting my AC signal? EDIT: I'll draw up a simple block diagram in the near future.