First time SRK build tech help!

Here is a chart from CREE on the emitter sizes. http://www.cree.com/led-components-and-modules/products/xlamp

The 3535 footprint has a very small thermal pad and this greatly limits the amount of heat it can get rid of. This leads to overheating when you put a high current LED on it without DTP.

The 5050 footprint would do the same thing with a low Vf LED, but at this point there are not any out that I am aware of.

Not seeing any of the XM-L 3D U2 emitters available on Digi right now.

MTN sells XM-L2’s along with lots of others.

Looks like Mountain Electronics has the XM-L2 U4 A1 available. Might go with these for now. 4.49 each at 6 emitters. don’t you hate making mistakes :person_facepalming:

I like the more neutral tints myself but everyone has their own opinions.

Does anyone make custom MCPCB’S that you know of?

There are some places that do but why would you need them? They are also pricey of course.

Those where the only ones I saw available right now.

Just a possibility for the SRK, would be nice to have a single copper MCPCB that fit the SRK. Wouldn’t mind spending 40 or so on it.

Many people have wanted this, the issue is getting it made. The buy in cost would be close to $1000 if I had to guess.

Then you have to figure out which SRK model you want to target, the 4x? 8X? more?

WOW! fare cry from what I was thinking lol. I see exactly what your saying though.

OK, just purchases the XM-L2 U4 A1’s from Mountain. Really not crazy about that temperature, a little to blue for my liking. But if I don’t like it I’ll order another set of emitters later lol

There was a company that posted a few months ago about custom mcpcb’s. I think Jos(Djozz) worked with them on a Nichia 119 copper star. If you do consider going ahead with that post an interest thread and I’m sure you’ll get takers, many of the early group buys were on parts as opposed to whole torches. Maybe RMM would be interested in stocking some along with his SRK drivers. 3/4 LED mcpcb’s will probably be the most popular as beyond that number the light turns into a flooder. It might even be possible to design one that fits either 3 or 4 LEDs.

To understand why LEDs overheat you have to understand the heat path. The led die that makes the light gets very hot and sits on a small square fiberglass substrate with thermal conduits from the die to the heat pad. This is soldered to the metal core pcb on +/- and heat pads which conduct the heat to the metal below. Most have a layer of copper, then an insulating layer, then the metal core. That insulating layer slows the transfer out of the die and into the core and when sharing the same core the back up can become critical and the LEDs poof. DTP (direct thermal path) has no insulating layer under the heat pad to slow the transfer and copper conducts heat much faster than aluminum so the back up won’t occur there, instead one must look to the next stage in the heat path which is from the mcpcb’s to the host, that is where your slug comes into play. It creates a buffer that also has more surface are in contact with the host. What you’re looking to do is create or maximize the ability for heat to move from the die(s) into the host and/or your hand. To do that you can try to maximize the surface area across each break in the thermal chain while minimizing the thermal resistance at these breaks.

If I do everything just right it should be one bright flooder. I’ll test each emitter after floating them to make sure all is good. Been wanting to do this for a while now and just ordered all the parts in the last couple of days. Texas Ace saved my skin big time by mentioning the foot print size. Now I have 6 extra XP-L2 V5 emitters to play with. I have gone over what needs to be done several times now. After the build I’ll use my thermal gun to see just how hot its getting when in full throttle. Between getting the wrong and right emitters that was about a 60 dollar pooch. Better then a smoking flashlight. A copper MCPCB for a 3 emitter would be nice.

I recently finished my first SRK build so I wish you luck. It was also a triple though I used some old T6 3D’s. Rather than Dremel the back of the reflector I cut some .5mm copper sheet to make thin buss bars to connect the 3 copper DTP stars and made a hollow copper puck for them to sit on. Dale did a version of the buss bars so I gave it a shot. The thing is stupid bright.

Thank you, cant wait to see the results. If all goes well I think a 3 emitter is next.

Those emitters will come in handy though I think you’ll find parts seem to accumulate more rapidly than finished projects.

Lol, Iv’e noticed that and I’m just starting out. Nothing like spare parts.

They come in real handy if you participate in the annual contest.