Luxeon in car

NightShift

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What resistor or type of resistor do I need to run a luxeon off of a car's voltage? Using 1/4 watt 22 ohm resistor gets the resistor very hot quickly
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. Im guessing its the amperage draw thats doing this? So what component do I use now?

Thanks
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P.S. - sorry for all the stupid questions...
 

PeLu

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by NightShift:
What resistor or type of resistor do I need to run a luxeon off of a car's voltage? Using 1/4 watt 22 ohm resistor gets the resistor very hot <HR></BLOCKQUOTE>

You have to dissipate about 3W of heat, so get a 5W resistor. 22 Ohm is a little low, take 27 or 33 Ohm. Look for a good heatsink.
 

NightShift

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Thanks PeLu for the answer.

Hmm, im assuming these arent widely available at your local radioshack (compared to 1/4 watt resistors) huh?
Seems i'd have to order them...does that sound right?

I was going to run the luxeon at 400-450 mA. I know this is a little overdriving it but it wont be run for long time periods.
 

Silviron

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by NightShift:
I was going to run the luxeon at 400-450 mA.<HR></BLOCKQUOTE>

I wouldn't..
The Luxeons can burn out "instantaneously" If you insist on overdriving it, work your way up slowly on each one you use as they vary a lot in what they will take.
 

NightShift

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Silviron:
If you insist on overdriving it, work your way up slowly on each one you use as they vary a lot in what they will take.<HR></BLOCKQUOTE>

If I worked my way up slowly, how would that help? As soon as I worked my way up to a value it didnt like, it would also burn out.

I've driven one accidently at like 1+ amp for a few seconds, about 650mA for a short time and 400mA normally so I figured that value would be safe, not saying that it is...
 

PeLu

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by NightShift:
Hmm, im assuming these arent widely available at your local radioshack (compared to 1/4 watt resistors) huh?
<HR></BLOCKQUOTE>

Assuming the 1/4 watt resistors cost next to nothing, you may just buy 9 or 16 and connect them 3x3 or 4x4 (4 in series, all 4 'chains' in parallel).
 
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