Reverse Binning a Luxeon emitter??

[PhotonFanatic]

Anyone out there capable of, or have the proper equipment for, determining what an unmarked Luxeon V emitter actually has as its Vf and lumen output?

If so, perhaps we could work a deal?

 

[idleprocess]

I'd think that Vf could be approximated with a multimeter and some sort of current supply (or some other means of limiting current).

Lumen output... would be a bit hairier. I suppose it could be approximated with an average mcd over beam angle.

 

[gadget_lover]

I can come close. I use a bench power supply and temp heat sink. I run up the voltage till it reads .350 amps. That's the VF at 20 degrees C.

If you then take the Lux reading at 1 meter from a white surface, you'll get a rough approximation of lumens. I put the LUT (light under test) at the edge of a white bucket and measure from the bottom of the bucket. It may be off 10 % or so, but that's good enough for comparitive purposes. A bare emitter will read close to what you see with an emitter in a flashlight.

The light meter was $49 on e-bay. The bucket was $9 when full of kitty litter.

I've ordered some diffraction grid from Edmunds Scientific to see if I can determine the tint well enough to say "this will be white" when it's hooked to the bench power supply. Diffraction grid ($7 for a 1 foot sheet) will break the light down to it's component parts. I hope to see extra green in my ugly ones.


Daniel

 

[RussH]

If you use a constant current supply, the LED will operate at Vf for that current, just like gadget lover's bench supply. That's what I normally do. If you use an LM317 and one resister, you might have to spend almost a whole dollar to build one. I built one for 50ma, 100ma, and 350ma (3 different resisters) for less than a dollar. Its a lot more portable than my bench supply. I have another for one amp with a 1 ohm 10w wirewound ceramic resister for Lux3s.
Do heatsink the luxeon, otherwise it can cook in just a couple of seconds. I use some little spring clamps I found at Home Depot and a 1/4" thick heat sink to test mine. I forget what current those Lux 5s are supposed to use, IIRC it's one amp. You would want a heat sink for sure. I'd use a 1 ohm resistor and check the actual current with my DMM. The resisters I use aren't all that precise anyway.

 

[kakster]

The Luxeon Vs are meant to be run at 700mA. 1 amp is quite a lot of juice to put through a Lux V.