LOC getting quite warm..

[meatballofall]

I'm using an LM317 ddl driver to supply about 405mA to my LPC-815. While I have the circuit running on a breadboard, I have the diode in an aixis module with two, DH dorcy original heatsinks around it. After about 5 minutes of continous running, the module seems to get pretty warm, almost uncomfortable to the touch. I plan on pushing the diode up to 420mA once i put it inside some kind of aluminum enclosure. Will this make the module warm up too much? I'd like to have an indefinate duty cycle along with the indefinate diode lifespan which is why i'm not pushing the diode any harder. But will it still be too hot? How warm, is too hot for the LPC?

 

[Mohrenberg]

as a general rule, once it is easily noticably warm, you should let it rest.....
and it should never get hot enough thats it's "uncomfortable" to the touch.

 

[meatballofall]

hmm... do you suppose i need better heatsinking? Something more than the two DHs? Or should I skip out on the 420mA like the LPC is supposed to be able to handle? And just... turn down the power a bit?

 

[ColdStl]

I've always wondered how long I could push a red diode at that mA setting as well. Based from what I've read on here, I try to limit my duty cycles to 1 minute or less for my LPC-815's

 

[john_lawson]

hey coldstl you get that LCC going yet :-?

 

[ColdStl]

Hi John... yep, @ 238mA on a v4. I tried it on an adj rkcstr but must've fried the driver on an earlier build because the diode didn't work until I used the lavadrive.
I have a LOC from a sf-aw sled on a preset v3 @300mA putting out 218mW. I have a feeling I can push this one a little more though.

One more LCC to go, and hopefully my 6x from scopeguy will get here soon!
Then I will have another red, which I plan on really pushing...

I didn't realize how much I like reds

 

[Meatball]

so should i back off the power? Or find better heatsinking?

 

[iskor12]

so should i back off the power? Or find better heatsinking?

Probably you need to do Both. An infinite duty cycle is hard to do at that amount of current unless you have some type of thermo electric or watter system to cool it. You maybe able to get it done if you had a huge chunk of copper hooked up to it

 

[Benm]

You wouldnt need an insanely large heatsink to keep it running fulltime - lets assume it runs 400 mA at 3 V or so, which makes 1.2W of dissipation (less really, as some of it - 200 mW or so - makes it out as light). You're looking at a 10 K/W heatsink to keep it comfortable (12 degrees over ambient).

At heatsink like this one is probably up to the job: http://www.dealextreme.com/details.dx/sku.9865

It's inner diameter fits an aixiz module reasonably well - you might need a small amount of thermal paste and a set screw to mount it properly.

 

[Meatball]

I like that heatsink a lot. But since the laser included is > 5mw, I don't think I could get it shipped here to the U.S.... Are there any heatsinks on there that don't include the laser? I looked but found none.

 

[Meatball]

who here on the forum can make me a large enough heatsink?

 

[john_lawson]

give me the specs i can do it

 

[iskor12]

If John Lawson can't do it, I most likely can, but it may take some time. Shoot, If I can get some time on a CNC machine here at the shop, I could make several for you. Too bad the gun industry is booming like crazy right now.

 

[Meatball]

haha sweet sweet. I'll PM ya those specs once I get them made up! Thanks!