any cree shakelights around
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f22shift
Flashlight Enthusiast
probaby uses too much power.
balou
Enlightened
That wouldn't work well... most of those shakelights are driven with far less than 20mA. XR-E's need about 20-25mA to light up... and their brightness is rated when driven at 350mA. That would give a few seconds of light per 10 minute shaking...
You could mod the LED with a Nichia DS or GS. They're 5mm LEDs, and are reasonably efficient with a few mA's
You could mod the LED with a Nichia DS or GS. They're 5mm LEDs, and are reasonably efficient with a few mA's
rockz4532
Enlightened
Unless you're superman shaking a huge light, then no it wont happen. a little capacitor or battery won't provide enough power to drive a CREE.
Federal LG
Flashlight Enthusiast
I remember someone around here that has this signature:
"A shakelight ??
"
"A shakelight ??
"
richardcpf
Flashlight Enthusiast
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- May 23, 2008
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You can mod a shakelight with cree.
If you want 5 seconds runtime.
If you want 5 seconds runtime.
Gunner12
Flashaholic
I'm not sure how much more power you get from a good crank light but a crank light might work. Freeplay had/has a crank light that powered a Luxeon LED.
Ty_Bower
Flashlight Enthusiast
Rubber-band powered Porsche?
I think it is a legit question.
Can't a cree be driven at much less than maximum? Is it still efficient at lower currents?
HDS/Novatac/Ra can drive the emitter at low levels. Does the efficiency change as a function of current?
Does die size limit the minimum current? Aren't these cutting edge emitters more efficient in general than older emitters?
Can't a cree be driven at much less than maximum? Is it still efficient at lower currents?
HDS/Novatac/Ra can drive the emitter at low levels. Does the efficiency change as a function of current?
Does die size limit the minimum current? Aren't these cutting edge emitters more efficient in general than older emitters?
Th232
Flashlight Enthusiast
From what I've heard, yes it can and is more efficient. The problem is how low is "low":
McAllan
Enlightened
It sure can. Perhaps you've tried taking an ordinary LED holding one leg with one hand and in the other hand holding a 9v battery. Now touch the free leg of the LED with the free terminal on the battery it'll glow (observe correct polarity) - how depending on how moisture your hands are. How that? Well, as said a LED is more efficient at lower levels and it doesn't have a minimum amount of current - as long as voltage is high enough that a very tiny amount of current can flow it convert amounts of the energy to light.
Do it with a Cree and it'll glow even a bit more than the average standard 5 mm white LED.
How it compares to a high performance like Nichia as low levels I don't know - haven't tried. But I'll almost bet the Cree will be a little brighter in a
light than the LED it got from the factory (they're most likely using the cheapest junk they can get).
McAllan
Enlightened
BTW. The limiting factor of those :green: lights is the capacitor. A Cree can not draw any significant power from it than the 5 mm LED. They're usually direct drive and if they're supplying too much they'll blow the LED. Those very high capacity tiny "super" capacitors can only deliver some mA and probably not much more even when totally short circuited.
Replace the capacitor with a more powerfull one and you'll instantly ruin the LED if not making a limiting factor such as a constant current diode (or FET coupled as such).
Replace the capacitor with a more powerfull one and you'll instantly ruin the LED if not making a limiting factor such as a constant current diode (or FET coupled as such).
balou
Enlightened
The Freeplay Jonta contains a 1W Luxeon. It's a crank- and not a shakelight. They state a cranking efficiency of 74%, which is pretty darn good. This light would just love to be modded with a Cree R2.
http://www.freeplayenergy.com/product/jonta
http://www.freeplayenergy.com/product/jonta
