Make:

The use of a resistor as the current limiting element is the primary drain on the batteries, drawing power and generating a considerable amount of waste heat. A constant current power supply such as a LuxDrives PowerPuck 700mA LED Drive Module is far more efficent. If you want to do constant current while staying completely DIY check out the designs these guys do:
http://www.e-f-w.com/community/index.php

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Yep, it's a bit wasteful - about 25% used is lost in the resistor. The aim was simplicity, however. I can't easily obtain Buckpucks, nor did I want to spend the time building a buck converter myself.

The 3021 Buckpuck drops about 1V minimum, so the efficiency gain in this circuit would be questionable at best.

I have another project on the site - a 9W mountain bike light. It uses a BuckPuck regulator to great effect. It's at http://www.mouldy.org/projects/High-Power-LED-MTB-Light.

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I've now built three lights - a 2x Luxeon III for my girlfriend, a 3x Luxeon III for myself, and a simple unregulated single Luxeon III (powered from 3x NiMH AA rechargeable batteries - the voltage match is such that you can get away without any additional circuitry at all - although the LED doesn't run at full power). Tail off is also a bit smoother..

http://buttersideup.com/DIYcycleLEDs.

I see that the white Luxeon III stars are now under $5! Pity I did these too early for the Luxeon K2s!

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I'm still suprised that not many people are using the 5watt Luxeons. I've had great rides off-road, using my DIY Luxeon V and getting 4 hr runtimes. Is it down to cost?

There's more info on my site, if anyone's interested:

http://www.outsider.plus.com/bikelights.html

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I built a DIY with 2 LXHL-NWE8 Luxeon Star/O - White Batwing. 3.42 Vf with an output of 45 Lumens. I wired them in series and I power them with a Shimano generator hub. I had to wire in a diode rectifying bridge to rectify the alternating current from the generator hub. I also wired a crappy capacitor to try and prevent flashing from the bumpy rectified signal. I never charge my batteries, I just switch on the light.

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Great things can be applied with luxeon led but yet were still under the big picture as luxeon has evolve to many application as flashlight to flouresent light... future still is bright for luxeon. Had anyone tried the 10watt police led @ gadget-junction.blogspot.com for more information.

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