Imagine a sine wave that varies between 1v p/p and 100v p/p. Now full wave rectified it without filtering. You end up with a waveform consisting of both 1/2 cycles in the positive polarity (not DC) that varies between 1v peek and 100v peek. This is the "input" signal. Regardless of the input voltage between 1v peek and 100v peek, I need to "output" a 5v peek waveform. I need some kind of AGC. A Zener clipper won't work because I need to preserve the sine wave. I'm thinking an Op-Amp with a JFET voltage to resistance circuit in the feedback loop. Since both cycles of the input are being rectified positive, the op amp's -V supply can be GND (no need for + & - power supply for op amp, only +). So in summary, I have a full wave rectified unfiltered sine wave that varies between 1v and 100v peek and I want to convert this to a constant 5v peek. Any help would be appreciated.