>I have given switching power supplies a close look, and they are definitely
>a much less crude solution than linear with huge heatsinks etc. I am just
>worried about the switching noise, which should not be a problem for the
PIC
>part of the application or the part that requires the high current, but
will
>probably be a problem for a strain gauge amplifier (instrumentation
>amplifier) I am using.  I have some questions to anyone who has experience
>mixing low level analogue circuitry with switchers:
>

I'm using both an LT1074 for a 0-30V 4A supply and a simple 7805 to supply
the PIC and signal conditioning circuit.  If you connect the grounds at a
single point so that you don't have large currents disturbing the
instrumentation supply, you shouldn't have noise problems.

The only gotcha's with the LT parts are using good coils and Schottky
diodes.  Otherwise, they are pretty straightforward.

Mark Walsh