Diamond Red LED for Mag Lite

[Just-Hunt]

Paul, do you think the 20mm star can be trimmed at all? The star I'm replacing is 16mm but this seems like a great LED.

Kevin

 

[Gryloc]

Hello. If it is not too difficult, I think that you can get some great results with the Luxeon III red or red-orange. The lambertian beam pattern would work better with the stock Maglite reflector, and this particular model of red LEDs can be driven harder, too. Therefore, it will produce more red light.

First of all, Cree sold the XR 7090 series of emitters (not to be confused with the XR-E) that covered all colors from red to blue, including white. The white XR was just as efficient as the luxeons of yesteryear. The reds were probably the same as Luxeon's in terms of efficiency. However, Lumileds stepped it up a notch when they created the Luxeon III version of the red and red-orange. It has a slightly larger red die so it can handle more current, but it also has a unique upside-down pyramid shape to it to increase light extraction. It seems like Lumileds knew how to get rid of all this heat as well. I looked up the datasheets to compare the two. Personally, I owned the red-orange Luxeon III, and it just blew me away. There is no way you can look directly at the emitter when running at the proper currents. It was easy to work with, and easy to mate with optics. I just may have to pick up another to make a coon searching light.

The Cree XR-series emitters (red and red-orange) were only rated to run at a maximum of 700mA of current, and they were meant to operate at 350mA. At 350mA, the XR-series red produces 40lm and the red-orange produces 49lm. I looked at the "Relative Flux vs. Current" charts on the datasheets, and I found that at 700mA, the flux increases by 150% (compared to at 350mA), so the red would produce 60lm and the red-orange would produce 73lm. Unfortunately, you will not see an increase of flux past 700mA (the curve flattens), probably due to heat issues. Here is the specifications sheet for the XR-series Cree emitters.

Lumiled's red and red-orange emitters were meant to be operated at 1400mA, and they have a maximum operating current of 1540mA (pulsed current max of 2200mA). At 1400mA, the red produces a minimum luminous flux of 90lm and a typical luminous flux of 140lm. In addition, at 1400mA, the red-orange produces a minimum luminous flux of 120lm and a typical luminous flux of 190lm. You can also under-drive the Luxeon III red-colored emitters. According to the "Forward Current Characteristics" chart on the datasheet, you will see 25% of the flux at 350mA (compared to 1400mA), and you will see 55% of the flux at 700mA. So, that means for the red, 22-35 lumens at 350mA and 49-77 lumens at 700mA. For the red orange, that means 30-47 lumens at 350mA and 66-104 lumens at 700mA. For those previous estimates, I used both the minimum and typical luminous flux times the percentage (for the min-typ range figures). Here the specifications sheet for the Luxeon III emitters.

I am not sure which would suite you best, the red or red-orange. The red-orange has a light frequency that our eyes are more sensitive (hence more lumens), but you want a LED with a light frequency that the raccoons are less sensitive to. The red emitters have a wavelength of light of 620nm to 645nm, and the red-orange have a wavelength of light of 610nm to 620nm. Would you know which would be better suited for this task?

I think the best setup you can have is the bare Luxeon III emitter attached to H22A's DHS heatsink with thermal epoxy. The emitter is available in small quantities from Future Electronics, and the heatsink from H22A. Then just use a driver from DX (like the AMC driver that can output 1400mA) to power the emitter from 3 C or D cells, or a li-ion cell. What do you think? This got me thinking and I will have to add this to the list of mods I want to do.


Cheers,
-Tony

 

[Paul Baldwin]

Paul, do you think the 20mm star can be trimmed at all? The star I'm replacing is 16mm but this seems like a great LED.

Kevin

I don't see why not, it's only 2 mm a side after all. If it was me doing it I'd just hold the star in a pair of pliers and use a bench grinder. I removed the led from the star to use with the KD setup. I've found that they are removed very easily by dropping them on to the top of my wood burning stove when the top is up to 250 degrees, talk about hi-tec!
Thanks Gryloc, that's loads of info! The main reason I went with the Cree is the directional nature of the light they produce. From what I have read on here they work particularly well with aspheric lenses, so I never really looked into the Luxeon versions. If the Luxeon output is that much higher I imagine the difference should be more than compensated for though?
My main problem with 1400mA would be supplying enough current. I'm not really into torches in a big way, I was just interested if I could make something usefull for someone who'd expressed an interest. The Duracells I have easy access to over here don't even cut it at 700mA :shakehead I can't warrant the extra expense of importing 10000mah nimh cells and a suitable charger at the mo. The charger I have takes 30 hours to charge a 2300mah D cell!!!! I've been looking for some cheap parallel 3xAA D cell converters but not had much luck.