Help! Where is a good place to "browse" Driver/LED parts on the internet?

I am wanting to look at a variety of different “pills” or pill components. I believe I understand the concepts fairly well, but I have never purchased any parts before, and am not certain where best to start. If anyone can recommend some online shops (Chinese OK) that have a good variety to choose from, I would greatly appreciate it.

- I am vaguely aware that most pills are designed to fit typical host sizes. I am not certain what that size is, but I am guessing about 25mm diameter. In my case, I have room for about 40mm.

- I would like to go as bright as possible, so I would like at least 1x XML Cree Emitter, but would also consider 3x if size permits.

- I only have about 25mm “depth,” so the pill needs to be fairly “short.” (I am willing to do without any reflector, if necessary.)

- I am willing to work separately with driver board and emitter(s), and build my own heat sink, if necessary.

- I am planning to run on at least 4.2v and would like to consider 7.4v (two Li-Ion cells in series).

- I am not concerned at all about runtime. I simply wish to blast as many lumens out the front as possible.

The idea is to make a “hot rod” out of an old broken flashlight, so the final product need not be practical. (Just shockingly bright.)

All comments, ideas and suggestion will be greatly welcome.

What light will it be used in? It's not really clear... pills are usually not interchangeable.

Antique 1929 Yale 2 x D-Cell. Sorry my post was not clear. Let me try to explain further.

I am not expecting to find anything “ready to use.” I am looking for a source of parts than can be used together and/or modified to make something of the appropriate size that will fit.

I believe I can make a “standard” 1 x XML Pill fit, because it is relatively small. But, I was hoping for perhaps 3 x XML, so I was hoping to see whether or not such a thing exists as DIY parts. If diameter is fairly close to 40mm, I may be able to “trim it” (grind it?) to fit.

If necessary, I am willing to buy Emitter “chip” (board?) and Driver board separately, with no pill or reflector at all. In such a case, I would have to make my own “pill” from scratch to hold it all in the correct position and provide heat sinking.

If possible, I want to “over drive” the XML Cree Emitter(s) to unusually high voltage such as 7.4v or 6v or 5v… What ever is able to achieve maximum output. In that case, I would want a Driver board that delivers such voltage.

My problem is I have no idea what kind of parts are available out there, and I am hoping to receive some pointers on where on the internet I should start looking. (Which shops)

For a host ~40mm diameter I can hardly think of anything that could suit a triple XM-L build. First you’ll need a thick custom heat sink (base plate for the LEDs) because the body of that flashlight is not going to dissipate much heat, secondly you will need 3x 18mm optics (I can’t think of any right now, they’re most in the 20mm size) and 3x 16mm XM-L.

To overdrive a LED there is no need to play with the voltage, just the current. In this case you will most likely need a direct drive driver like the BLF17DD, this will push the XM-L near the limits (About 4A per LED). But the problem here is the host itself, the switch, the spring, and even the body is not designed to carry that many amps.

Websites like and carry a wide range of parts for DIY projects, I believe there you can find a clearer idea of the mod.

Personally if I had a vintage flashlight like that I wouldn’t bother modifying, I would just restore it nicely and keep it as is. Why? Because in a couple years XM-L will be considered obsolete technology… but that 1929 Yale will retain the same value over the years.

Well, this particular flashlight has a bad crack that needs to be soldered, or repaired in some other manner. Except for the crack that opens up the threads prevents the head staying on the body, this old light actually works on 2 x D-cells, right now.

It may seem wasteful to “gut it,” but I am hoping to keep the old parts, so that it can always be put back together in original shape. However, please think in terms of a “hot rod” that is built on a Model T body, but has a huge supercharged motor; that is kind of what I have in mind.

Frankly, this flashlight has almost no value as a collectors item. If you keep you eyes open, you can easily find similar flashlights in much better shape for around $20.00 on eBay and other sources. Some particularly rare items sell for several hundred or even several thousand, but such truly valuable antique flashlights are quite rare. Many that are very interesting looking and in good mechanical condition (fully functional) from the 1920s or 1930s can be had for a few tens of dollars.

Thanks for the place(s) to start looking. So far, I have gone entirely through what I believe to be all the parts available on DX, and the following photo shows what seems to be the most interesting so far:

I think it will easy enough to trim this to fit. But, the next question becomes: what LED emitters to use, and where to get them. Can I buy “bare” Cree emitters? Will XML emitters likely fit on this aluminum “base board”? (If necessary, I am willing to give up on XML and use another (decent quality?) emitter, if those will fit better on this board.

I will take care to make certain to add plenty of good heat sinking material to this contraption. I will now start looking into a driver board, but can I find one that will drive 5 x XML at 4A?

I like the layout of the FastTech site for just browsing components... You can drill down to just drivers, just emitters, or whatever under the flashlights category...

I skimmed the thread, so sorry in advance for that.

  • For ~40mm I’d look into using the Ledil or Khatod optics. Ledil’s Cute-3 or Cute-4 line is available to fit XM-L2 emitters. Khatod should also have compatible optics.
  • XM-L2 or XP-L is what you want for this hotrod, not something else. That’s assuming that you want it to produce a “wall of light.”
  • The product you pictured in Post#5 is for a very old emitter. It appears to be compatible with Luxeon-I emitters (and modern generics), this would not be acceptable.
  • Does this flashlight have a large lens on the front, rather than a reflector? This could affect your build goals if you consider doing an aspheric thrower. Use search if you don’t know what that means.
  • Look at lagman’s thread here to start trying to understand drivers - Understanding the difference between Linear, Buck, Boost and Direct Drive drivers
  • Shop for drivers on,, and
  • Research driver testing done by HKJ at
  • Understand that driving 5*XM-L2 emitters at 4A each is 70W of output power before driver losses. Around 88W including driver losses. You cannot build this flashlight in such a way that it can handle that continuously. If you are determined to do so, research turbo stepdown or turbo ramp-down. You may want to look into a custom firmware such as STAR - STAR Firmware by JonnyC - Source Code and Explanation.
  • In my opinion you should reduce your power level.
  • You can’t run anything like what you want on 2*D cells, so you need to consider what type of battery conversion you will do. 8*AA might be a good idea, or 2*26650 or 2*18650.
  • Look at these two graphs (which djozz made) of XM-L2 and XP-G2 to better understand the current-vs-voltage relationship with these things - Crash-testing a XM-L2 and a XP-G2 on copper Sinkpads

Also Rosoku Chikara, it would be helpful for you to mention your approximate budget if you have one.

I think with the lens in front you are pretty much stuck to a single led and a reflector is not necessary. If there is a reflector, spherical or nearly so centered around the LED would be good and not blocking the direct path to the lens. Does it focus? Looks like the lens and bezel might screw in and out.
Or maybe three LEDs so close to the lens that their patterns overlap in the center. Or three different colors would be cute.

I like Mountain Electronics and Fasttech, but sometimes International Outdoor Store and Dx have things I need. I get things from Illumination Supply in San Jose but mostly because it is close. Once you get an idea what you want, you can Google it, ignoring adds.

Thanks for the many valuable suggestions and advice. It will take me some time to “digest” all that you have written.

But, your last question I can answer easily enough: as little as possible, but I am certainly thinking in terms of spending at least $50.00 over time. Frankly, I have no idea of what it “should” cost, to “do the job right.”

(By over time, I mean I am not planning to buy everything at once. I am wanting to get the physical parts configured in such a way that they will fit, and temporarily use an 18650 for power to test the circuitry. (I probably wouldn’t even try to put the 18650 into the flashlight, just connect it by separate wires to the customer driver/LED “pill” that I am willing to build.)

I am thinking to establish the lens and LED configuration first, and then make certain it will all fit. Then purchase a driver and make sure it works electrically speaking, next. Early on, I am thinking to purchase some brass plate that can be cut into a disc or discs to increase heat sinking. (Actually, after looking at thermal conduction properties, it seems aluminum is perhaps better than brass, and certainly much cheaper.)

The last thing I will do is make some kind of adaptator for the battery. I thought that I needed high voltage, so oddly enough, I was thinking of serial 3 x AA adapters to generate around 7.2 volts. (Two such serial adapters in series would fit perfectly, and I would power it with something like AA Eneloop Pros. But, I am not certain that even Eneloop Pros can handle the necessary current, however.) And, even such serial adapters are not all that cheap…

Anyway, withing reason, I am willing to spend what it takes. But, I probably won’t want (or need) to spend it all at once. Right now, I am just enjoying myself thinking about the design.

Thanks for your help.

You are welcome.

  • Brass takes solder without problem. Aluminum does not. Therefore brass is easier to assemble. Copper will also work in this respect.
  • Depending on what you end up doing, high voltage may or may not be an asset. Eneloop XX (Eneloop Pro in Japan? I can’t remember.) can handle 5A without a problem I think. Regular Eneloop can handle 10A without a problem. Probably both will have somewhat reduced life. HKJ’s website (which I linked to above - also has lots of great data on batteries.
  • $50 may be fine for LED (s) and driver. It depends on your choices though. An expensive driver, optic, and MT-G2 could end up putting you over that mark. The same goes for a 5*XM-L2 setup, which typically starts with around $35 worth of emitters on Noctigons! You’ll almost certainly need to budget some more money for brass/materials as well as batteries charger etc.

Maybe there is an easy way. Looks like a small 18650 zoomy minus the sliding head or bezel and lens would fit inside, giving you everything you need. You would only need to figure a way to reach or otherwise activate the switch. Then you could use the usual modifications on the zoomy to get the current up. My SK-73 fits inside my 1929 RAY-O-VAC 2D light head and all without taking out the spring or reflector. The body of the zoomy would be the heat sink.

I understand what you are saying, and even considered something like that already. As you say it would be much easier… But, I am not sure it would be quite “hot rod” enough, and to me, it takes away from the “conversation value” of the customized light. Once some one understands that it is simply a modern flashlight hidden inside a large antique flashlight, that kind of “takes the fun out of it” for me. I would much rather be able to remove the rear battery cover and slide out 2 x D adapters, and say “Yup, they really knew how to build them back in those days… See here? It runs on regular AA size batteries, too.)

I did a similar project when I first started, using alcohol cooling, a cheap plastic host and D cells. My main problems were: An incandescent reflector is too long focal length for use with an LED facing forward. Only a little yellowish light hits the reflector. And. The alcohol softened the epoxy. Also it took four D cells to push the cooling till I got bubbles, and I started with only two.
I thought of trying one with the LED facing back as a retro-reflector light with the alcohol to solve the inerrant cooling problem, but I put together a light with a large Fresnel lens and didn’t need another thrower.

Thanks, now I understand why brass is better.

Interesting. Are you saying that regular Eneloops can handle more current that the Pros? (Yes, XX = Pro in Japan) I am not too worried about reduced life. I am thinking of a “Turbo Timer” (based on my looking at the BLF17DD driver suggested by will34) and don’t plan to use the flashlight much… Probably it will end up being a “battery holder” for some backup cells that I can rob in times of need, for other applications.

Actually, I was in the process of editing my previous post a bit when you wrote your reply. As I tried to make clear in my edited post, I really don’t know how much I “should” spend, but in principle, I am willing to spend what it takes.

Thanks again for all your kind advice.

At least two 18650s will fit in. Since it doesn’t have to be practical, you don’t need a driver, just a resistor or steel wire to keep from frying the LED or LEDs. Use IMR cell in series. Or Really high current 14500s (from Mountain Electronics) look like AAs.

It can be easy to get drawn into heated pseudo-academic discussions around here about what material is “better,” so let’s not spend a lot of time discussing that. As I understand it brass is easy to machine, takes solder, and has similar thermal properties to aluminum. Those are all admirable properties. If you/we avoid the use of words such as “better,” “best,” etc it will probably save us all some heartache. :~ Sorry to be melodramatic!

You intend to assemble a custom pill. I assume that you do not have access to equipment such as lathes or milling machines. Therefore I think brass is an appropriate choice.

…. moving on… :smiley:

I may have forgotten the truth of the matter when it comes to Eneloop vs Eneloop XX. Glancing at HKJ’s data, I see that both types were tested at 10A and did OK. Older XX versions did not hold voltage as well as regular Eneloops beyond 5A. New XX cells (labeled Panasonic, but maybe not in Japan) seem to do better than new Panasonic Eneloops.

Anything of that family of cells is probably fine at 10A.

Lists various drivers and their capabilities:

Well, thanks everyone for all your kind advice and comments. I am still working through everything that has been posted, and trying to understand everything. In the meantime, I have found some parts that would seem to be quite appropriate for this project. I may look for some cheaper alternatives as I go along, but these appear to be readily available at

Here is my concept sketch:

Does this sketch seem doable? I can add more heat sinking material if necessary…