Luxeon LEDs ... but what type?

[Magic Matt]

I found some Luxeon LEDs in my electronics box. I think a couple are Luxeon III and a couple are Luxeon IV, but I can't be sure. There are no markings on the packaging. I figured it might be cool to try and make a light with them. I think they're brightly coloured so not much good for a torch.

I think I Need a heatsink so I was thinking I'd just use a little thermal paste and stick it to an old P4 CPU Cooler until I find a way to work out how big a heat sink I'd actually need. Do I need any special components to wire them up, or could I just try hooking them up to a basic battery and resistor circuit?

 

[HarryN]

Both lux Is and IIIs have a Vf around 3 - 3.5 v and can handle 500 - 1000ma, with heat sinking.

Lux Vs have a Vf of about 7 - 7.5 V, as they are basically 4 die wired 2S2P, and designed for 700ma max. Make sure it is well heat sinked, but temp setups can work.

An easy test setup is to try 3 alkaline cells and a 1 ohm resistor - pretty foolproof for quick testing and no chance of over driving it.

 

[Magic Matt]

Thank you!

I don't suppose you know how I can tell which are which do you? With such a big difference in voltage it would be nice to pump them at the right level and get full brightness (or near to).

 

[yellow]

Lux I and Lux III are the same,
Lux V is dramatically larger emitter die.

the V fills the transparent dome nearly fully, the I and III die looks "lost" in the middle of the dome

 

[HarryN]

If you use a constant current source, it will not reallly matter. The optimum current for all of them is around 700ma.