Thum,
I am a fair weather rider myself (till I find me a foulweather rider that looks good) so my lighting rarely sees rain. However I have been caught in a thunder shower before and to my surprise a 5min ride going (no bike computer on the bike I was riding but I have a bike computer on the other (displayed on my Flickr) ~20kph pouring hippos and elephants didn't short out the lighting on the quad damage. Perhaps it was luck but this happened about 5 times now so I'm thinkingi t's because I put silicon on the LED lens/holder as it's sitting over the LED to seal out as much moisture I can think while also having that hold the lens holder in place without falling off.
You sound geeky. If you have a spare heatsink off a computer you can hacksaw the heatsink and use that as the LED heatsink. Make one light a la 'ghetto' style first then rip it apart later and use those parts on something else. I would recommend going with a 2-3 LED DIY unit. DX has good prices on it's parts and is mostly a one stop shop without the neeed to pay for shipping. I used the LED Stars. For the more skilled people they use the emitters which I've heard are a little harder to work with. The regulators I recommended above both will work with 3/4/5/6AA batteries allowing you excellent flexibility should you be riding farther awa or if you're local and in the woods or away from home you could ask/barter for some extra cells and keep on going being you can run on a min of 3 cells. Note that 3 cells willnot be as bright tho. I built mine on flexibility as I was thinking down the line I may want to go travelling and also I lik to be able to get power from anywhere.
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