My potential OSHW universal programmer project needs a programmable power supply that can do two 0-25.6V +-0.1V rails, and +5V to power the microcontroller. I want the variable supplies to be able to both source and sink current. I came upon a nice power opamp that could do it -
L165V from ST.
However, it needs power supply at least 3V above and below of what it will work with. That means +29, -3V.
I would have to go for a 30V AC transformer to supply the power to this. I can't get hold of anything other than 2x15V one for a reasonable price.
Now to the poblem: All I have is 30V AC, rectified to about 42V DC. I need a virtual ground, and not in the middle even! (Lets ignore the +5V rail for the moment)
I would need two caps in series, with ground in the middle, and make some balancing circuit to split the ~42V rectified to charge the upper one to ~+33V and the lower one to ~-9V... then put normal linear regulators against the virtual ground to turn it into stabilized +29, -5 rails - right?