This article is from the Misc Bicycles FAQs, by various authors.
From: firstname.lastname@example.org (Mike Szelong -District Manager)
I cooked up a homebrew that was the hit of a ride last week. I took a
Malibu light replacement (around $8, I think at Home Depot), the kind
that is used in the yard to light up a path, and wired it to an old
nicad battery- 12v that came from a laptop computer.
The battery is a little large, about 4x5x2 inches but it powers the 12
volt 15 watt light brightly for over 2 hours and over 3 before its
dead. The night suns on the ride had two lamps and more adjustability
but this setup was competitive. I believe that there are smaller
output Malibu replacements that are around 7 or 8 watts, suitable for
smaller battery packs.
The Malibu lamp replacement is a reflector/lens that has two spade
terminals and two screw terminals on the back. I took a piece of sheet
metal, (a slot cover from a PC) and drilled two holes in it to match
the screw locations with one being a larger size than the other. I
then found a plastic insulator (like the kind used to mount a power
transitor to sheetmetal) and used it to isolate the one terminal from
the sheet metal. I secured the lamp to the sheetmetal with the screws
provided and bent the sheetmetal 90 degrees and duct taped the sheet
metal to my handlebar stem. You could easily use a hose clamp, I
didn't have the right size handy.
- insulator | / | _ _ |===================== ====| |===== ^ ^ | | Holes---------|
____--------------------____ / \ \ / \ / \ / \ / | \___________/ | X _ X _ |=====================X====|X|===== X X = = = = ^ ^ | | Screws--------|