I recently bought two sets of super regulator boards and assembled them. My preferred parts supplier (Digikey.com) didn't have the BC556AP, so I used a BC557BG. I used a BC547B for the negative. Checking the spec sheets, they have exactly the same properties except for a maximal voltage of 50 rather than 80 volts.
I doubt this is related and assume that these parts work. However, to my great chagrin, my boards are not working properly. Rather than giving me the calculated output voltage, it gives me a constant +7.1V and -16.4V with the sensors properly connected. Changing the voltage divider resistor does not change the output voltage. I've checked the parts multiple times, but haven't discovered the problem. What am I missing here?
Your post answered my questions. Thanks a lot.