Jim Weir published this a few years ago. I just finished (cobbled
together) one & am trying it out. Note that it has to be on the
battery for weeks & that the average current is like a trickle charger.
I had a couple of the output IGBTs fail though I'm pushing the supply
voltage. Go here for details:

http://www.rst-engr.com/kitplanes/KP0204/KP0204.htm