So I have built two flatline compressors. I built one from the PCB layout in MarkM's gallery, and one from Ulysses' vero. Both have the same issue. Neither are actually compressing. I used a homemade photocoupler from an LED and an LDR in both. On both of them, when nothing was happening, i cut open the shrink on the photocoupler and realized that the LED was just on and staying solid. any ideas?
R.G.'s PCB layout is proven. Just make sure the traces for the bias part in the circuit have continuity. There was some defect in the PCB I made for it about 4 years ago and I couldn't get bias voltage. I wound up creating a daughterboard with a 386 bias circuit, but never completed the pedal.
Have you tried different LEDs & LDRs?
I built one of these using R.G.'s layout an it works beautifully. John Lyons etched me a real nice board (shameless plug :D)
I used a VTL5C3. My favorite guitar comp to date.
Dave
Hmm, I'll try R.G.'s layout then. I'll report back with results!