Fpund this
http://www.firstlightoptics.com/prod...omiser300power
Looks pretty handy if it provides the correct polarity and regulation on the voltage and current at the right DC levels for the 40D , not many dark sites or parks have mains access so the Canon 220VAC convertor kit for the 40D is - well - next to useless for astro imaging.
Anyone splashed out and bought one of these ?