Originally Posted by steelbikeguy

that's a home-built LED headlight. I think it is my 3rd generation of LED light... or maybe 4th?
It's pretty basic, and optically similar to a flashlight. i.e. no optimization to put the light out below the horizon.
The most unique feature might be the standlight, if only because it uses a 100 Farad supercapacitor for the standlight. It'll run for about 10 minutes at a much higher brightness than commercially built lights.
Having a standlight run for a long time can be inconvenient, so I included a switch to disable it. I mounted a magnet on a rotating plate on the right side of the light, and it controls a reed switch on the inside of the housing (the reed switch used to be a sensor for a bike computer). This is just a way to avoid exposing a mechanical switch to the weather.
a shot of the front of the light...
and a shot of the inside. You'll note the big green thing that takes up about half of the space... that's the 100F supercap, and explains why commercial lights normally use a little 1F supercap.
Steve in Peoria
(you should see the tail light!)