It occurred to me that if one is willing to sacrifice some flexibility in the decay length of my compressor design; that it can be simplified by removing the source follower and the Zetex current sensor. What this means is that the control voltage is only half wave rectified instead of full wave, but if you just increase the filter cap – the circuit should still work fine. The trade-off is that you get limited to longer decay times only, but for most guitar applications this is fine. I have not verified this circuit but I will do this soon. I am confident it will work well. Removing these parts may make it more attractive to the DIY builder.