52mm reflector - which emitter should I use?

hi, this is my f1rst post here I'm pretty new to all this flashlight stuff, but I own few cheaper lights from DX (with XML and P7) and I've got a pretty good expirience with electronics
I'm building my first from-scratch build, I'll be using this reflector:
http://www.dealextreme.com/p/alumin...or-cree-mc-e-led-emitters-52-15-27-15mm-39409
and some 1A driver board for the LED, it will be powered with 2x 14500 LiIon's. I'm building it inside a 50mm PVC pipe (100% waterproof :devil
well and the question is, which LED will give me more throw? XR-E R2 or XP-G R51B? I'd prefer to use the xp-g because it's brighter, but will it be a thrower?
thanks for advice

3zuli said:

hi, this is my f1rst post here I'm pretty new to all this flashlight stuff, but I own few cheaper lights from DX (with XML and P7) and I've got a pretty good expirience with electronics
I'm building my first from-scratch build, I'll be using this reflector:
http://www.dealextreme.com/p/alumin...or-cree-mc-e-led-emitters-52-15-27-15mm-39409
and some 1A driver board for the LED, it will be powered with 2x 14500 LiIon's. I'm building it inside a 50mm PVC pipe (100% waterproof :devil
well and the question is, which LED will give me more throw? XR-E R2 or XP-G R51B? I'd prefer to use the xp-g because it's brighter, but will it be a thrower?
thanks for advice

Click to expand...

I just used that reflector for a maglite build with an xm-l, it worked out really well. The only problem was mounting the led (I used the copper base star model from dx). I had to grind out the underside of the reflector with a dremel and use flat desoldering braid for the leads in order to keep them from shorting on the aluminum. You could use a plastic ring to isolate the leads, but the led will be further away from the ideal focal point.

I would go with the XP-G, but that's because I like the higher total light output and increased efficiency. I think if you want a dedicated thrower, the XR-E will work much better, not to mention that due to the design, it will probably fit a lot better in the reflector designed for the MC-E.

The little ring (should) fit right into the hole, and due to it's increased height over a standard led dome, you will probably have way fewer problems with a plastic isolating ring or whatever else you come up with.

I used the P7 model, but I'm guessing it's similar, and one other thing you'll want to watch out for is the distance between the back of the reflector and the base of the brass ring that screws in. The star I used dropped right down into the brass piece, but when fully tightened, it would just flop around, probably about 3mm away from where I wanted it. I had to make an aluminum slug to fill in the gap. A larger star MAY sit on top of the threaded area and fit in perfectly, and there are plenty of threads to accomodate that situation.

The star I used was 18mm. I would give you the exact dimensions of the other mating parts, but the light has already been given to my brother in law.

It's hard to say, XR-E is going to have a tighter beam but the extra lumens in the XP-G probably make up for that. I am saying that irregardless of the reflector because it is made for neither of those LEDs. If you want throw away or paint the reflector and use this.

http://www.dealextreme.com/p/50mm-18mm-2-80-degree-glass-optics-12834

2 degree beam divergence when focused correctly.

I am building my own PVC based dive light, word of advice, PVC has very low thermal dissipation characteristics if it is fully sealed, even with an XP-G driven low it's going to get toasty. Irregardless I would suggest that you start with a Mag mod before building your own bodies.

thanks for the help guys.
I'll probably use the R2 because there will be more space for the wires between the reflector and star.
well I won't be running this for hours LOL, so this should work fine (I can probably make some extended heatsink around the pill). I think the aspheric lens would complicate the entire build

I just did an XR-E bike light that consisted of a 1.75" long mag slug surrounded by cardboard as a spacer in a steel case. After 15 minutes the slug was over 160 degrees F. This is a lot more thermal capacity than you have and sealed in PVC will take forever to dissipate. You may not cook your LED but you will definitely drop efficiency.

-B&C

BlackAndChrome said:

If you want throw away or paint the reflector and use this.

http://www.dealextreme.com/p/50mm-18mm-2-80-degree-glass-optics-12834

2 degree beam divergence when focused correctly.

Click to expand...

I'm also planning to use that optics. Are there any gaps when you put that optic in a mag lite? I thought maglite lens are 51.2 yet those optics are 50mm.

3zuli said:

thanks for the help guys.
I'll probably use the R2 because there will be more space for the wires between the reflector and star.
well I won't be running this for hours LOL, so this should work fine (I can probably make some extended heatsink around the pill). I think the aspheric lens would complicate the entire build

Click to expand...

I've been meaning to do a write up on my build, I have all the pics, I'll see if I can throw it together today or tomorrow, it may be helpful to you. If you do an extended heatsink you'll be all set, just remember to make as much metal to metal contact as possible with pressure from screws, the threads on the parts themselves, or whatever else you may come up with.

Oh, and do what I keep meaning to do, and document and share the process so that other people don't have as hard of a time when they do something similar.

Dealextremes caliper measurement shows that they are just slightly oversized. you're talking about .5mm difference in radius, not enough to be any problem.

I'm meeting my friend today to discuss the machining needed for this project, I must turn down the oudside diameter of the reflector in order to fit it inside the tube and I'll ask him about the extra heatsink
I'll order the LED and other stuff today

edit: so I met him and here are the results: I'll heat up the end of the pipe with a hot air gun and then (while the PVC is hot) twist the reflector in. also I'll make 2 small cuts on the front side of the reflector, this will allow me to untwist and remove the reflector (if needed).

BlackAndChrome said:

If you want throw away or paint the reflector and use this.

Click to expand...

I've seen some posts where people would keep the reflector. Any difference in throw output if you keep or don't keep the reflector with the DX 12834 lens?

update: I successfuly melted the reflector into the pipe, now waiting just for the parts

beekeeper5 said:

I've seen some posts where people would keep the reflector. Any difference in throw output if you keep or don't keep the reflector with the DX 12834 lens?

Click to expand...

if you keep the reflector inside and use aspheric, it won't project only the image of the led chip itself but also image of the reflector

The XR-E has a narrower radiation angle than all later LEDs.

So for best throw, if using an Aspheric, use an XR-E, it will be easier to get more light onto a long-focal-length lens.

If using a Reflector, use anything other than an XR-E - its narrow beam will be concentrated inside the reflector opening, contributing more to spill !

the parts arrived today! I already assembled it, the throw looks to be very impressive (will test it tonight) and has good spill
took me about 2hrs to complete




spot from 3 meters

you can see the other pics here (non-english): http://forum.fotonmag.cz/index.php?showtopic=1831&st=0&gopid=39072&#entry39072
thanks for the help guys

3zuli said:

. . . if you keep the reflector inside and use aspheric, it won't project only the image of the led chip itself but also image of the reflector

Click to expand...

But the Aspheric can't focus the light that's come off the reflector.