Alright guys, thanks to nitro for being a US distributor of Ahorton's aspheric lenses, I'm building two identical aspheric builds with Solarforce L2m's. One will be going on my AR-15, and the other will probably just sit around the house.
Now I have a few questions for the experts around here.
1.) What Cree LED should I go with? I like to order from US distributors, and ledsupply.com and illuminationsupply.com only have XP-E's (R3 and R4). I have some extra XR-E's sitting around, but I can't remember what they even came out of. It seems as though the XP-E would work great, but some say the XR-E is ideal.
2.) For my AR-15, I have a big pack of CR123A's sitting around and in my "bugout" bag. Using a 7135-based driver with one CR123 won't get me to max output, and 2 of them would burn up the 7135's (correct?). For a 17mm driver, outputting just over 1 amp, are there any other options? If not, I'll just run an RCR123 to get max output, then sacrifice output if I ever have to go to the CR123's (really, this won't happen).
I have a great idea for the heatsink, which will basically be a solid slug of copper or aluminum that fits inside the body and bottoms out where the body narrows down to 18mm. The 20mm LED star will be mounted on the front, and the driver on the back. Then two small screws or a pin will hold it in place, which means there won't be any spacers, and the twist of the head can be used to get the emitter in perfect focus. I'm sure this has been done before, but I'm excited to give it a shot.
Now, I just need to figure out where to get the slug of copper/aluminum, and if I should have someone like Chicago X machine one for me ;)
The super-budget way would be to get a 3/4" copper bushing and pressure cap.
Cut the bushing down to height, then cut the pressure cap roughly in half. Turn it around, then solder to the top of the bushing. This will make a 'cup' in which to place the star, as well as a lip to hold the lens at the correct focal length.
Well I received (5) aluminum 7/8" x 3/4" slugs, plus (2) copper ones from www.speedymetals.com (just a few towns over from me). I plan to go aluminum simply because the copper is so dang heavy (this is a lightweight AR build). Drivers are on their way (just 4 x 7135 from illumination supply), and hopefully the XR-E's as well.
Well I got my first prototype done (almost). I still need to grind down the bezel to fit flush.
I ended up using a random EZ900 XR-E that I had sitting around, mounted to a 7/8" x 3/4" aluminum heat sink, along with a 4 x AMC7135 driver so it's running close to 1.4 amps. The heat sink was then drilled and tapped, and the Solarforce L2m body was drilled and countersunk to fit a 3 mm hex bolt. This allows the focus to be adjusted, as there is no spacer in between the LED and the lens.
I'm using an Ahorton aspheric, but I have to say I'm a bit confused. I have some super cheap aspheric lenses from DX, and that was what I previously used for the light mounted on my rifle. Yet the Ahorton's shape results in a much larger projection of the die. I'm going for max throw here, so this is rather depressing.
On the left is the DX lens, on the right is the Ahorton.
I have XR-E R2's waiting to go now for the real build, and have some heat sinks on the way from Chicago X (which will be completely true and smooth, compared to my hacked up one above).
ChicagoX is correct. The focal length affects spot size and not throw. The lens diameter affect throw. If both the Ahorton and DX are the same diameter they will throw the same distance.
The shorter focal length (Ahorton) is closer closer to the emitter and therefore results in a larger emitter image. You get a larger spot that throws the same distance as the smaller spot.
If you have a light meter you can verify that. The lux reading should be the same from the DX and Ahorton lenses.
Lens quality makes a lot, just check both yourself and decide which throws further, in real situations they do not always perform as you may think in the first place, I've got bigger lenses doing it worse than smaller ones and vice-versa.
Alright guys, hopefully you can answer this tonight before I complete my build. Using just an aluminum heatsink, should I run the XR-E R2 at 1.4 amps or remove a 7135 and run it at 1.05 amps? I don't mind if I cut the life of the LED, just as long as I won't kill it with moderate use.
My UltraOK (Q5) draws 1.7-1.8A from battery without any special heatsinking (hollow pil in a MRV type body). I rarely have it on for more than 3min (although I do that daily), but someone else reported testing his for 15min on High with no problem.
EDIT: The above current values are from a DMM (20A range) with very low internal resistance. From another DMM (10A range) I get 1.4A from battery.
Run it at least at 1.4 amps. I would add a chip and run it at 1.7amps. A R2 XRE pulls 1.8amps when fed direct drive. I have been running one in a P-60 host at 1.8amps for a couple months with no damage.