OFNA Ultra GTP / MBX conversion

[BrianG]

If I built it, it would probably be fairly large, like the KoolFlight BEC - maybe a tad smaller. Much easier to use one of the devices Arct1k linked to (except weed out normally-closed models): http://search.digikey.com/scripts/Dk...ormally%20open

A fan speed controller is unnecessary IMO. It's not like you are trying to maintain a specific set temperature, but rather just keep it cool. And TBH, just an inline manual SPST switch to the fan would be adequate and simpler.