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From: barton@latcs1.oz.au (The Wasp)
Newsgroups: sci.electronics
Subject: Inverting DC
Message-ID: <8984@latcs1.oz.au>
Date: 12 Oct 90 22:34:08 GMT
Organization: Comp Sci, La Trobe Uni, Australia
Lines: 25



     I've designed a linear regulator to provide me with 0 to 100V (actually
it's much more general - it'll regulate anything I put into it), but it's
_only_ a positive regulator. I'm designing a power supply around it, and I
want a 0-100V and -100-0V (common earth) with INDEPENDENTLY variable output
levels, so:


         control 1   control 2
        |          |          |
        O          E          O
    -100 to 0V             0 to 100V
     wrt E                   wrt E

   My problem is that while I can regulate the positive side, I can't use my
design to regulate the negative side. If I use the same design for both sides,
but invert the negative side (ie multiply it by -1), I'll achieve my goal,
but I don't know how to do this. Does anyone else? (Obviously op-amps are
no good, since they're usually only good up to about 18V.)

     Please email replies, as I don't often read this group.

Thanks in advance,
Doug