Mega headlamp
I switched to headlamps from flashlights around the time I started climbing. I was flush with cash from living a .com moonlighting funded grad student life, and I poured the excess into gadgets for my new sport. I bought a lot of devices of questionable utility, but headlamps are one class of tool that I have continued to find very useful. In France, I had a friend who did ski de randonnee at closed ski resorts during the night. He was able to do this through the use of a mega headlamp with a gigantic battery that lived in a backpack. I've wanted one ever since, despite not having very much justification for buying one, but could never really figure out why they cost $500.
Fast forward to a few weeks ago, when I found a post by one of the Squid Labs brainiacs on how to build a mega headlamp with a relatively small battery pack and newly available ultra bright LEDs. I spent some time agonizing over how to improve on his design, but in the end just decided to build it as specified. I sourced my parts from Future Electronics and Battery Junction, and bought the rest of the parts at Al Lasher's Electronics on University (my childhood haunt).
Overall, I followed the instructions, but went with a potentiometer instead of switches to fixed resistors. I used 10x 2600 mAh Tenergy AAs and white Luxeon Stars (I don't believe the whole blue/green thing being better for night vision). The heat sink was off a pentium III and the head harness was off an old and extremely useless Princeton Tech headlamp. I hacksawed and drilled some aluminum stripping to mount the light assembly to the harness. Once I had the parts, I finished all the soldering and assembly in a few hours, and figured out how to mount the lights to the harness in another half an hour.
I'll post pictures, but this thing is BRIGHT! I've been blinded by it a few times, and it leaves a pleasing blue ghost image burned into my retinas (that's good for them, right? Survival of the fittest rods and cones?)
Things that I learned:
I SUCK at soldering
you don't need very much thermal paste to make a gigantic mess
The curing time of some silicone sealers exceed the maximum limit of my patience
Things to do next time:
Use an audio/log pot for power control -- linear is ridiculous
Use less glue
do a better job attaching the star plates to the heat sink
Use fancier LEDs -- the ones I use are about half (if that) as efficient as the cutting edge in LED tech.
edit: added picture