Luxeon v Primer
kelvin james
Posts: 531
Or, how to almost smoke a $25 led. The local electro store had these, so i thought, cool --- a 5 watt 700 ma, burn your eye balls out led to play with. This is star pcb with the solder pads and the heat sink. Well, i found out it is really not a heat sink, but a heat sink pad. I discovered this when i fired it up and a nice little trail of smoke started to rise from the led. And another slap to go with it was, i checked the voltage coming from my ratshack variable supply, at 7.5 volts i was getting 9.6 volts on the meter, not good.
Yeah, i know, mentioned many times before, but some of us were born to learn the hard way. Bought a $35 bench top variable supply, on the meter it reads only .02 volts off any voltage setting, not bad at all. So, off to the the store again to get a heat sink, not a hope, just some little crappy ones that would not do the job. After some pondering, i thought i would look at my old pc boards, and there they were. Big heat sinks on those AMD cases with 2 dual fans on each one. To make it short, i cut down the heat sink to the size i needed, still big enough to hold one of the fans. I sanded off some of the paint on the heat sink, and used some silver epoxy to fasten the led to it. I am just using the 5v supply off the BOE to run the dual fan.
So far, no problem, with the fan overall temp is around 30 c., without the fan, maybe 5 degree warmer. These leds are really bright, very hard on the eyes, so use caution if you attempt to use them. Next step here is to make a switching circuit with a stamp and a TIP32. By the way, i plan to use these for some portable lighting, and some emergency lighting as well.
Post Edited (kelvin james) : 2/25/2008 5:30:01 AM GMT
Yeah, i know, mentioned many times before, but some of us were born to learn the hard way. Bought a $35 bench top variable supply, on the meter it reads only .02 volts off any voltage setting, not bad at all. So, off to the the store again to get a heat sink, not a hope, just some little crappy ones that would not do the job. After some pondering, i thought i would look at my old pc boards, and there they were. Big heat sinks on those AMD cases with 2 dual fans on each one. To make it short, i cut down the heat sink to the size i needed, still big enough to hold one of the fans. I sanded off some of the paint on the heat sink, and used some silver epoxy to fasten the led to it. I am just using the 5v supply off the BOE to run the dual fan.
So far, no problem, with the fan overall temp is around 30 c., without the fan, maybe 5 degree warmer. These leds are really bright, very hard on the eyes, so use caution if you attempt to use them. Next step here is to make a switching circuit with a stamp and a TIP32. By the way, i plan to use these for some portable lighting, and some emergency lighting as well.
Post Edited (kelvin james) : 2/25/2008 5:30:01 AM GMT
Comments
Check out http://www.candlepowerforums.com/ for all the latest LED tech.
Thanks for the info on the Cree led, big advantage over the Luxeon. I see Honeywell has a patent infringement suit against Phillips and Cree for the technology used in these leds.
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Paul Baker
Propeller Applications Engineer
Parallax, Inc.