First time SRK build tech help!

Oh well, you can use the L2’s in some other lights. I am really liking the L2’s in my other lights if you don’t do a lot of white wall hunting.

What you want are some basic XM-L2’s in the tint of your choice. I have an 8x 3D U2 version that works great and has around 10k lumens with a TA driver (was around 8k with the FET+1 V2). The tint is nice and they work just fine.

Thank you Texas_Ace. I think I pooched all my orders :person_facepalming: I have a couple BLF 16mm Copper MCPCB XPL XPE XPG Direct Thermal Path Circuit Board coming that I don’t even think the emitters I ordered will work with.

Yeah, the xp-L2 is the same footprint as the XP-G series. They use the 3535 footprint. So they will work fine on those mcpcb’s, Although I am not aware of a BLF brand of mcpcb’s. I have been using the ones from simon (convoy) for all my lights.

Thanks again, all just learning stages and I appreciate the heads up big time. I’m looking now on Digi for the right Emitters. That site can be difficult to navigate but I’ll find them eventually.

Can you explain why this happens?

The 5mm and the 3.45mm foot prints. If you install a 3.45mm emitter on the 5mm board the neg and pos will touch causing it to ground out and boom, no more flashlight.

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.