>a Switched Mode PSU controler, I have my doubts.  You can already buy many

The AstroFlight http://www.astroflight.com Model 1xxD chargers are
essentially SMPS devices, and are controlled by a PIC16C71.

A friend of mine did the design.  I'll have to open it up again and review
the electronics, but as I recall the PIC does everything, including driving
the switch.

Andy

==================================================================
 Eternity is only a heartbeat away - are you ready?  Ask me how!
------------------------------------------------------------------
andy@rc-hydros.com      http://www.rc-hydros.com     - Race Boats
andy@montanadesign.com  http://www.montanadesign.com - Electronics
==================================================================