wow! Very neat and ingenious piece of work OL and worth a 10% increase in output, which isn’t to be sniffed at. Is that 10% difference greater than the expected margin of error (i.e., is it due to the Cu star or just LED variance)?
Thanks to Match too, for the testing data. How did the OL Cu star compare with your XM-L reflowed onto copper?
Have you or anyone else tried the copper stars from DX yet? I’m ashamed to admit it but I have them but have never tried reflowing anything yet. I’m going to have to one day very soon. Seems like it may give the same results without the added expense or time involved. It wouldn’t give the great feeling of satisfaction of making it completely for yourself but I think I could get over that. LOL
The “solder it” stuff from Kesler leaves some residue, IMO. They also make one specific for
copper . If you solder onto copper it can be a little difficult if you dont have a high output iron.
The copper solder paste makes it a bit easier to work with.
I have been trying out the other paste I linked to in the first post and I like it so far. Low melt and seems to be pretty clean. I have only used it a couple times. I plan on doing a little “copper star assembly line” when I get some leds in, then I will have more experience with it.
Edit: The solder it paste from Lowe’s was not the best. I ended up squeezing out some on a cardboard and mixing it up well before using it. It seemed to work better. I also tried the “copper solder it” from Lowe’s. I threw that stuff away. Don’t need more high melt stuff.
I like the way u think. good ol yankee ingenuity. u’ve given me a few ideas for future projects. i’m kinda surprised that tape provides enough mechanical connection for the wiring pads. let me know how u center the led.
Once again, you impress. I’ve been wondering lately how to use a 1/2” copper cap to make a pill and you light the way. A bit of 1/2” inside to add mass and a bit outside 1-2mm longer than the cap for driver recess and follow the recipe above. Scratch lines in the first layer might help with keep the pad stable.
This suggests there is more gains to be had from reducing led temperature, as i had assumed they reached their lumen output ceiling due to saturation or some non heat related reason. I wonder if some kind of active cooling, say a peltier cooler, or fan connected to the heatsink behind the led would make a significant difference.
To me, it’s just like a processor for a PC. Cooling is the key. Water (or nitrogen) cool a LED and the sky is the limit. Well at least we don’t know the limit for sure until that is done.
- Test was performed exactly as all of my emitter tests - which is mounted to a 1lb piece of copper barstock imbedded in a 25lb block of aluminum.
- Heat is the key. The cooler an led can be kept, the more power it can be fed to produce more light.
- I have @ 10 150w peltier coolers at work that I could stack together to get an led close to cryogenic...but other than academic interest a test like that wouldn't have much bearing on what could be done in relation to a flashlight.
The results from that test are here. For Justin's benifit, I sent him a graph depicting all three tests.
I agree, you can’t easily put a peltier cooler into a flashlight, so i guess its more of an academic interest. I assume at some point the wires and junctions in the led will fry from the voltage and current if you keep the temp low enough for that to happen.
We could always start a betting pool to see what amperage and lumens a U2 XM-L can take before non heat related failure