[0-30 Vdc Stabilized Power Supply]

But a low voltage negative supply is needed because the output of U3 must go negative enough (about -0.7V) to allow D9 to force the output of the project to 0V when the output is shorted.

Ahhhhhh that makes sense.  I was wondering how that all worked, but now its clear.  Thanks!

I'm in the process of scrounging up parts for this (I would like to make a dual rail one for +/- supply needs).  Hopefully it all goes well.

-Dan

[0-30 Vdc Stabilized Power Supply]

I'm in the process of deciding on a design for a lab power supply, and this one seems to fit the needs that I have.  However, I have been reading some of the forum replies and I have a question.  Why are you guys using OP amps that aren't rail to rail?  If you used a rail to rail amp, it would eliminate the need for the charge pump negative voltage generator and make life a whole lot easier.  Am I just missing something, or is there a reason for using non-rail to rail OP amps?

Thanks,

Dan