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Using the circuit here: http://en.wikipedia.org/wiki/Joule_thief

I screwed a AA holder to my TrackClip pro, and it runs well on one 1.2v AA NiMH rechargeable cell. I was able to fit all the electronics inside the clip itself, so the only thing that sticks out is the battery. I measured the current draw, it's about 60mAh, so it ought to run about 2500/60 (about 40) hours per charge if the spec is right on the cell.
[img:right]https://fbcdn-sphotos-a.akamaihd.net/hp ... 7664_n.jpg[/img]

Very nice! I like the 1 battery modification alot.

very cool man. good job

Very cool. Any chance you could post a how-to on doing this?

Thanks

I tore a ferrite toroid off an old motherboard and used some enamel magnet wire (30 AWG), 20 turns on each side.
Make sure you reverse the turns for the sides!
For the transistor I just picked the super common BC547B transistor. You should be able to use just about any small signal NPN transistor though - this is a pretty inexact circuit. I used a 1K resistor on the primary coil, specifically a common 1/4 watt 5% carbon film( see http://goo.gl/ZLXk0 )

If you pick a smallish toroid, you can solder everything up and pack it on the gap in the clip without too much issue.
I was able to use an energizer 1.2v NiMH cell for about a month before it had to recharge... which was good, DCS A10 was hard enough without having to worry about the sensor

If you guys need more help, let me know and I might go ahead and post a more thorough guide.

Oh, nice. You packed the joule thief into the existing TrackClip Pro housing?

Yes. Actually, if there was a lot of interest, this wouldn't be too hard to make en masse as a more legit pcb design.

Thanks.

This is so cool - I literally cringed when I saw the Trackclip pro was USB. (Mostly because my Belkin USB HUB just died the notorious overheating death) but at least they thought ahead enough to let you piggy back another usb device onto it.

For something that clips onto your head a battery powered version is a no brainer?! I already look geeky enough without even more wires coming off of me lol.

Did you make any other changes to the wiring of the TrackClip Pro (different/removed resistor), or did you just connect the positive and negative of the Joule Thief in place of the positive and negative from the USB port?