I thought someone might also be interested in my compressor design. It originated from looking at the Orange squeezer, but has more features, namely, totally discrete signal chain, gain control via a H11F1M opto FET and uses a zetex ZXCT1041 current sensor as a ideal full wave precision rectifier. I also have a simple op amp implementation that works fine(for rectifier) but the ZXCT1041 is really great for converting signal level to control voltage- it works reliably up 50Khz or so. The circuit provides control for compression level and out level. Its quiet, has no critical adjustments and uses little power.