Playing catch-up with Cree... some questions

Hi all,

I spent more time selling stuff than buying lately-I'd been away from the forums-but I finally had to see what all the Cree mania was about.

I got ahold of an Ultrafire C2 and a drop-in for a Z2 and am tickled to death with both. Finally-something I can see with for a change here in the sticks on roads so dark I can't see my hand in front of my face! That, plus really shot night vision. So I need BRIGHT! That C2 is pretty insane. :huh: Chinese knockoffs go against my principles but on a disability income they are a godsend... expensive light days are over. Now, except for my 10X and M3's, I can't go back to yellow incan for P60-lumen-range lights.

That said, here's the poop. I don't have any knowledge of compatibilities for modding, like optic/reflector types, changing emitters to existing Luxeon lights, etc. I guess I'm really looking for a parts list, as it were.

I have two ARC's and two Longbows I'd like to do. So... 1) Can I change emitter-for-emitter in the ARC's with no hassle hacking the electronics on the original board? Which optic or reflector would I use? 2) Since the Longbow board is potted, is there a dropin available for it? 3) Has anyone come up with an MN10/MN11 dropin type thingie for the M3? I'd like to do at least one without getting a whole head, which is $$ prohibitive.

I haven't tried an SSC light yet. How do they compare with Crees? With the positive ground thing I read about here though, seems like they'd be a modding hassle.

Only if it turns out to be a real PIA, I might sell the Longbows/ARC's, which I really don't want to do, (especially the ARC's) and just replace. That's a last resort though. Stay tuned though.

Thanks for any help in getting up to speed!

Rich

Cree: narrower radiation pattern than Lux, different overall package, +/- more clearly labeled.

Seoul: radiation pattern similar to Lux, overall package similar to Lux, notched negative side like Lux, weird gummy dome, stories of tint-shifting at high drive currents, emitter area 0.03" lower than on a Lux.

I hate soldering Crees. Seouls are much quicker, and you can use them in Lux-based lights with little or no reflector modification.

TigerhawkT3 said:

I hate soldering Crees. Seouls are much quicker, and you can use them in Lux-based lights with little or no reflector modification.

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Don't most lights use stars, not bare emitters? What's so hard about soldering stars?

He probably refers to emitter soldering, which is much easier with the souls than the crees.

I can understand why soldering Seoul emitters would be easy, but I've just taken a close look at a Cree and it looks like it has quite accessible pads - on the top, too.

TorchBoy said:

I can understand why soldering Seoul emitters would be easy, but I've just taken a close look at a Cree and it looks like it has quite accessible pads - on the top, too.

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1) The solder doesn't always stick properly to the contacts

2) The contact points are located such that your solders have to be flat, otherwise, the reflector you use may not sit properly around the emitter if the solders are too thick.

TorchBoy said:

I can understand why soldering Seoul emitters would be easy, but I've just taken a close look at a Cree and it looks like it has quite accessible pads - on the top, too.

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If thermal-epoxied to a heatsink, it actually takes a decent-sized bit to heat up the Cree pad sufficiently to solder to. My narrow circuit-soldering bit can't supply heat fast enough, so I have to swap to a heavier one.
I find (as do some others) that even with a good bit, solder doesn't seem to want to stick to the tinned pads. I dremel off the preapplied tinning and tin with my own solder, which seems to make a real difference. Possibly there's just oxidation on the tinning and some gentle scraping of the surface would do the job just as well.

I used to work in defense electronics so the soldering won't be a problem, believe me.

My question is, can you drop it into the place of a LS without f***ing with the regulator board in an ARC or Longbow, and getting good output?

Rich

richpalm said:

I used to work in defense electronics so the soldering won't be a problem, believe me.

My question is, can you drop it into the place of a LS without f***ing with the regulator board in an ARC or Longbow, and getting good output?

Rich

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Yeah, that part isn't a problem. Since you're swapping the whole star, the only issue with the Cree in this case is the narrower radiation pattern. You might get holes, rings, splotches, or other issues. You could fix that by installing an appropriate aftermarket reflector, but you might as well just get a Seoul.

Or, of course, you could buy both, try them, and share your results.

richpalm said:

I haven't tried an SSC light yet. How do they compare with Crees? With the positive ground thing I read about here though, seems like they'd be a modding hassle.

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Hi Rich,
The SSC's aren't bad at all. The wires attach the same way as a Luxeon, but the bottom of the emitter will have voltage present. Simply isolate it with Artic Alumina thermal adhesive. You have to use some kind of heatsink compound on emitters anyway, so this isn't really too much trouble. If you're using SSC stars, there's no isolation to worry about. The emitter's slug is already isolated from the rest of the star. Just swap it in and go. Some reflector clearancing and/or emitter height adjustments might have to be made, but not always.

Have fun!