Home-built cree mr11

[ovlovder]

Here are some shots of my lamp so far. I hit a roadblock when one of the posts broke off my optic, waiting for a new one from cutter...

whole story here

 

[znomit]

Can you post images here please, MTBR requires a login to see pics.

 

[ktronik]

IMHO you will cook the LEDs if you don't somehow thermally connect the heatsink to the housing... is it connected??

I have done many hours of testing 3 LEDs driven @ all levels...& if you want to run it @ 750-1000ma, the heatsink you are using is NOT enough, despite what anyone will tell you...

again MHO...

K

 

[StevelKnievel]

Yeah,

Listen to Ktronik. He's right.

 

[Metroid]

Courtesy pics:

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[ovlovder]

 

[ovlovder]

IMHO you will cook the LEDs if you don't somehow thermally connect the heatsink to the housing... is it connected??

I have done many hours of testing 3 LEDs driven @ all levels...& if you want to run it @ 750-1000ma, the heatsink you are using is NOT enough, despite what anyone will tell you...

again MHO...

K

I have a thin aluminum wire sleeve that will bridge the gap with some Arctic Alumina for good measure.

Thanks for the concern, honestly, thats why I posted...

 

[ktronik]

ok... have you got a temp probe on your voltmeter??

get one on the heatsink & see how hot it gets...then do the same on the case...the difference in temp after 5min, will tell you if its working or not...

K

 

[ovlovder]

How hot can these things get without overheating?

 

[ktronik]

this is just tests I have been doing, their is a lot more to it than just a few numbers...but a ball park number would be as below..

for a small to mid size heatsink.

heatsink temp

20-50deg mid level
50-90deg high level (over 60 not the best for long time)


The LED junction temp is what really counts...

I say over 60 as if you touch the heat sink or light... you may get burned

K

 

[znomit]

Is it possible to disassemble it quickly?
If so run it on low for 10 min with a fan blowing on the unit. It shouldn't be more than warm. Pull it apart and see if the plate the LEDs are on is significantly warmer than the casing.
Try again up to high power. Things shouldn't ever feel too hot to hold .

Some more pics of the innards would be great too

 

[ovlovder]

With no airflow, after at 15 minutes, it has not dimmed, my bFlex is set to 50degrees, and very close to my heatsink, housing is hot, but not so hot you cant hold it. The heatsink when pulled my seem slightly hotter. Need a non contact...

 

[Zero_Enigma]

With no airflow, after at 15 minutes, it has not dimmed, my bFlex is set to 50degrees, and very close to my heatsink, housing is hot, but not so hot you cant hold it. The heatsink when pulled my seem slightly hotter. Need a non contact...

I'm curious about the bflex/nflex temp sensing mounting. Do you use Artic Alumina Silver to glue the b/nFlex green circuitboard to the casing?

Or do you tape the n/bflex to the housing and hope for transfer of heat?