Variable Bipolar Power Supply

[jfice13]

As a followup, I do realize that the op-amp does not have a resistor on it's positive leg to counteract the input bias current as it should for a precision integrator. Obviously you'd want to use something like a JFET input op-amp with low input bias current and a resistor that on the positive leg that is equal to the equivalent resistance seen from the negative leg to mitigate integrator error.

Like I said previously, however, this is just a quick schematic for a proof of concept and the values don't really matter nor does it have all the trappings of something you'd want to build.

 

[Roff]

Jfice13, much of this thread is about stability and transient response. Read my post #11. It suggests adding the cap to make an integrator of the op amp.

 

[mneary]

Obviously you'd want to use something like a JFET input op-amp with low input bias current and a resistor that on the positive leg that is equal to the equivalent resistance seen from the negative leg to mitigate integrator error.

Not obvious to me. The worst bipolar op amp I could find has a worst case bias current of 1.5µA. Even if you fail to put a resistor in the (+) input, the 6k ohm equivalent resistance could cause an offset error of only 9 millivolts. I would select an op amp based on input offset voltage, which rules out most JFET input op amps.