Cree XRE thrower

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Hmmm

Newly Enlightened
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Apr 26, 2009
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I'm working on a aspheric lgith. I'm Thinking of using a peltier to cool the led, run the led at around 2 amps, machining a costum light, and controlling the peltier with a attiny 13a and a transistor. I found out that the five cree xre q5 leds I have are ez900 ones. I discovered that after accidentally de doming 2 of them when desoldering. 😳:sigh:🤢. That was sad. I can't find any tests that show at which temperature they run the best. I saw one test here that showed someone got almost 500 lumens out of one with a similar setup.

I'm thinking of using the 62mm dx aspheric if I can't find any nice large ones. I'm took 2 old pennies, sanded and then soldered them together, drilled a 3/16 hole through them and soldered a brass piece of rod in. I couldn't find any copper rod. I'm planning on directly soldering the led to it and sanding the rod down to a few mm above the pennies. I'm going to solder the pennies to 1/4" thick piece of copper to act as a heat spreader for the tec.

How does this sound?
 
Hmmm said:
I'm working on a aspheric lgith. I'm Thinking of using a peltier to cool the led, run the led at around 2 amps, machining a costum light, and controlling the peltier with a attiny 13a and a transistor. I found out that the five cree xre q5 leds I have are ez900 ones. I discovered that after accidentally de doming 2 of them when desoldering. 😳:sigh:🤢. That was sad. I can't find any tests that show at which temperature they run the best. I saw one test here that showed someone got almost 500 lumens out of one with a similar setup.

I'm thinking of using the 62mm dx aspheric if I can't find any nice large ones. I'm took 2 old pennies, sanded and then soldered them together, drilled a 3/16 hole through them and soldered a brass piece of rod in. I couldn't find any copper rod. I'm planning on directly soldering the led to it and sanding the rod down to a few mm above the pennies. I'm going to solder the pennies to 1/4" thick piece of copper to act as a heat spreader for the tec.

How does this sound?
Click to expand...
Pennies aren't copper, they are copper plated zinc. I would not use them for this.
 
bose301s said:
Pennies aren't copper, they are copper plated zinc. I would not use them for this.
Click to expand...

Not entirely right, but there's some truth to this. I modded my Arc6 with penny shims (1981 and older), these are 95% copper and 5% zinc. But yes, 1982+ are mainly zinc (97.5%). Just use the older ones.
 
help? I'm thinking of using the 75mm aspheric from dx, saabuster said it is poor quality. Has anyone else had something positive to say about it?
 
The DX 75mm can be good, but if you are unlucky it is bad, it is not consistent quality.
On Ebay there is the shop called top-ledlight, and another called wellparts, they have 75mm aspherics. I would try those first.
 
Last edited:
Walterk said:
The DX 75mm can be good, but if you are unlucky it is bad, it is not consistent quality.
On Ebay there is the shop called top-ledlight, and another called wellparts, they have 75mm aspherics. I would try those first.
Click to expand...

I tried to find those on ebay, but coudln't. Could maybe send me the links to them or maybe post them here (don't know of this is allowed)?
 
I will look for those. Today I built a new heatsink with a piece of 3/16" copper sheet, some pcb board, and some brass rod. I soldered the led to the brass and i put together a simple constant current supply set for 2.2a. I'm planning on driving it and the peltier off of 2 lifepo4 18650s in series. I'm having some problems with the led icing over. Should I tape a desiccant pack in the light head once I make it and just fully seal it and not open it again? Maybe assemble it in a freezer? I'm planning on pwm controllening the peltier with an attiny. I'll have a temperature sensor on the hot and cold side and if the hot side gets above a certain temperature I'll lower the power of the peltier and the led and check until the temperature is a certain preset max.
 
Last edited:
ok thank you. What is a max recommended current for a cree are q5 ez900? I'm driving mine at 2.2a and have read that is too much for it. I understand the ez1000 can be driven as high as 2.5a with extreme cooling. I'm been running mine at -30 degrees C which is lower than i will be in the light.
 
The 66mm lens that I have has a focal length of around 40mm.

You have to be carefull with the led, better start at low amperage and see what it does when the current goes up.
1,4 Ampere is about standard, 1,8 is about the highest sensible but if your set up is good AND you have luck with the led it can take 2,2 amp.
You just have to try...

What do you use for power or driver for the led?
 
I'm planning on using 4 A123 Lifepo4 18650s in a 2s2p configuration, with a switching buck driver for the led and I will directly power the tec.Currently I have the led directly soldered to a b rass bar abut .5cm long which is connected to a peice of 3/16" copper.
 
Variable output driver would be great.
The TEC would be more useful if you ad a fan to the heatsink most likely.
Any picture of the set up?
 
i'm still waiting on the tec from ebay. i have several but i have trouble removing them from the heatsink. Anyway to remove thermal glue?
 
here is the assembly:
i'll test it:
imag0582q.jpg
 
i'll post some new photos tomorrow, i'm building a better setup.
 
The principle is good.
Really good cooling might give you around 10%, maybe 15% more output.
I think the heatsink on the back should have fins and might be a bit larger, the larger the better the temperature is taken from the led to the air.
And maybe a bigger plate on the front, the same size as the peltier?
 
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