luxeon help - total newbee

[teststrips]

I just recieved my first luxeon from a very friendly and good natured friend from the threads (dimwatt). It looks exactly like this one - link

I've worked with many regualar 5mm and 3mm leds in adding them to my PC, swapping better/whiter/brigher leds into my led flashlights, and I even modded my first solitaire. But to get right down to it, i don't know a thing about these luxeons. I can see 4 basic traces from the pic that I linked to.
top left - very small eyelet
bottom left - leg 1
top right - leg 2
and the other trace is on the bottom, and I'm assuming it's for heatsinking purposes.

also how much voltage/current would I need to feed this thing?

I figured to make this 1st luxeon mod as easy as possible I'm going to put it into my biggest light (which sucks as a huge incan) - a 3 "D" cell craftsman.

If you could also point me in the right direction on if I'll just need a resistor to Direct drive this thing, or if I'll need a more complicated circuit.

Sorry for all the newbee talk, I've tried searching, and found the feature almost completely worthless. Adding a + for a 2nd search criteria usualy does not work at all for me, it usually just searches like an "or" search on google anyways.

 

[HarryN]

Since you are already familiar in general with LEDs, you are ahead of many of us when we started.

The first stop would be to Lumileds.com for a look at the products and data sheets.

The larger tabs are the anode / cathode. The small ringlet IDS that side as anode (+).

The underside has a metal area - this is a heat sink, and MUST be used. It is highly recommended to have electrical insulation, but thermal conduction to a heat sink - at least 1 in2 per watt, 3 is better. If you forget to do this and run the power for more than a few seconds, two things can happen
- The LED will be ruined
- If you touch it, you will remember the experience and will likely not repeat it. /ubbthreads/images/graemlins/frown.gif

Typical currents range from 350 ma to 1 amp, depending on which part it is.

 

[teststrips]

how important is the material used for heatsinking? Must it be alluminum or copper, or would a stainless steel bolt head work OK?

 

[Leeoniya]

any metal will do. however, copper and aluminum will give you best reults. here is why.

copper has a very high thermal conductivity factor and aluminum has a real high heat dissipation factor. this is the reason for copper core, aluminum fin hybrid heatsinks.

however, Silver has an even higher thermal conductivity factor, making it superior to ALL. (actually an alloy called Cusil (72% silver 28% copper) is highest but for all practical purposes it's silver)

see this table:
http://www.frostytech.com/articleview.cfm?articleID=233

an ideal heatsink is silver mated to an aluminum flashlight body. I'm looking into incorporating this into my designs soon. I found a supplier of 10ga (0.102") sheet sterling silver. i think the 6"x2" is $64 without shipping. but thats pretty cheap, all things considered cause u'll get about twelve 1" dia 0.102" thick stamped heatsinks out of it. making each heatsink cost roughly $5.

also it's a good idea to lap (polish) and clean (with alcohol) the slug on the bottom of the emitter.
you must always use thermally conductive grease like Arctic Silver or Arctic Alumina, or an epoxy of the same kind when you attach the emitter to the heatsink itself. otherwise there is no good thermal path from the die, no matter what kind of heatsink it is.

hope that helps,
Leon

 

[teststrips]

I'll keep the questions coming. Dimwatt (the guy who sent me the "gift" of this LED had also recieved it as a gift proir to sending it to me) is not sure of any specs on the led. he suggested "I would check with some of the more experienced moders as they use a multi meter to ascertain voltage"

So is there a way of figuring this out using my DMM

 

[Leeoniya]

you can check some specs, like Vf and If, but you need a spectrometer to be able to determine tint, and even that's not 100% accurate. same goes with brightness and needing a light meter or integrating sphere if you have the money. of the 3 parameter code found here: http://idleprocess.net/pdf/luxbins.pdf

you can only determine the last one with good accuracy.

if you have a DMM, and preferably an adjustable pwr supply that can supply enough current (hopefully more than 1 amp). connect the DMM inline (measuring current on the 10A fuse) and slowly turn up your power supply to a voltage that would put the rated current through the DMM. that'll give you the Vf. the tit you can guess but you have to have several known bins to compare to. same with flux.

you have to make sure you have a source that can supply enough voltage without sagging. this will give you the most accurate measurement.

you can find the specs for rated currents on Lumiled's site.

Leon

 

[operator_smooth]

If the voltage drop across the LED is something like 3.6 V @ 350 mA then my guess is that you have a 1W lambertian emitter.

Maybe this document can be useful to you: http://www.lumileds.com/pdfs/DS25.PDF

 

[teststrips]

I finally got my heatsink ready last night, now I realize that I don't know how to attach the LED to it. I know everyone talks about Artic Silver, which I have some (from computer CPU upgrades), but do I need the Epoxy type, or can I mix it with superglue, regular 5 min epoxy, etc?

 

[Leeoniya]

i dont think the superglue idea is good, just out of principal. you're better off just using the thermal compound under the slug and pressing it tightly on the heatsink, this will stick it there very well. well enough in fact that all you need to do is solder the contacts to pads and you should be okay to go.