Luxeon Star LED's

Lumen is total light output. It is like saying "equivalent to a so-and-so many watt lamp". Not that Lumpens match watts, but you get the idea. A 10 watt lamp can be in a reflector in which case it is very bright in one direction, or it is not and it is rather weak in all directions.

MCD is millicandela which is candlepower. It is how bright it shines. The more directed the higer the MCD or candela rating. That is why ultra-bright LEDs hardly can be seen from the side.

Now back to the Luxeon: compare the power input of the LEDs for comparison. You have 12 LEDs now at 30 mA each at 3.something volt each. That is just above a watt. You can expect the Luxeon 1 watt to be in that ballpark. But the Luxeon will radiate in a wider pattern I think.

Thomas

Thanks Thomas for answering question 2 for me. So what you're saying is a 1W Luxeon would be *about* the same brightness as the LED globe I have? Hmmm. I think I'll need to aim for 3W luxeon (would that mean up to 3 times brighter than 1W? Sorry, dumb question, lol).

Now I just need help on question 3 from somebody. =)

Regards, Jason

I think I found something....

Almost certainly not. I have a Jaycar 12led headlamp and a proper Princeton Tec EOS 1W headlamp. The Princeton tec EOS blows the Jaycar out of the water. The EOS for example can easily light up a 30m high waterfall at night from about 30m away, the Jaycar throws a very dim light by comparison. The EOS does have a proper designed reflector though, designed for long throw with a mild dispersion pattern. The Jaycar is simply the LEDs on their own with a wide pattern, the reflector in it does nothing. You can get the Star with or without a built in reflector/lense I believe, and that will make a great difference depending on the application.

Essentially, yes.

What do you want to use it for? Dave :)

Hi Dave, thanks for your input.

I want to use it for a disco light - The light beam will just be thrown around in a dark room at various speeds (will be used with a pan/tilt module I am working on). =) .... with other lighting and party fog, of course! I will be using collimating lenses with the star to get a nice, sharp beam. I want to adapt LED technology and try and get away from the incandescent stuff.

I can see you can get *coloured* stars! Only seen 1W and 3W ones. I wonder if you can get 5W ones as well.

Jason.

Sounds like fun!

For indoor use in the dark at close range I'd suggest that the 1W would be plenty. The 1W is terribly blinding if you look directly into it, I can't imagine what the 3W or 5W would be like. The 1W is much cheaper too of course.

If you are pulsing the LED with a long off duty time then you can probably get away with a much smaller heatsink than recommended.

Now I'm thinking a modified spinning disco ball with a 100 x 1W Stars - that would be something!

Dave :)

The Stars require a constant current supply, so the simplest solution would just be an LM317 connected in constant current mode. Not the most efficient with 12V input though, as you'd be wasting about

Dave :)

That might be true, but I'd rather too bright than not bright enough... I will probably go for the 3W. I am thinking 5W would be too bright too. Pretty expensive anyway.

Well, now that you mention it, I wil be using both methods.... steady and strobing. Will therefore need to use the recommended heatsink for steady mode.

LOL! That would be very fiddley!

Jason.

"Jason S" wrote in news:4494fb3a snipped-for-privacy@news.iprimus.com.au:

I was in Wal-Mart yesterday,and they were selling a 3W Luxeon LED replacement lamp for Maglite 3-cell flashlights,for $19 USD.

It didn't look like it had proper heatsinking at all,it looked just like an ordinary lamp base.

Not exactly a bargain at those prices.

More than likely it will be running overly hot so output will be a bit low and life/degradation seriously affected.

However bear in mind that the low voltage lamps used in small hand-torches have horrible lifetimes (nom lifetimes can be as low as 25 or 50 hours) but give a usefull life because 'household' torches are not used very much at all and even when used - not for very long at a time. Stored away between uses the battery voltage is often well down giving a much extended lamp lifetime and a miserable light output.

The high color temperature of the leds used in these torches leads many to assume they emit more light than is the case. The small source dimensions also make them appear 'brighter' which is good for marketing if irrelevant to their use.

The 5 watters have a bit less efficiency. I really never heard of the 3 watters. The star has a wide dispersion and the lens that fits over it will concentrate the beam. I allready thought of the disco light while playing with these. I have 9- 5 watters right now, just the emitters, no attached sink from Luxeon. It too bright to look at without any concentration. I can pulse up to 65 watts withg this setiup.

greg

Thanks Greg, I am definately using lens to concentrate the beam (probably the 15 or 25 degree), and nobody's gonna get a chance to stare into it because the beam is going to be moving quickly, and needs to be bright enough to be noticable in party fog. Being LED and all, I wasn't sure if 1W was going to be strong enough, thus the thoughts of a 3W =)

Jason.

Right now I am going to try and remove Leds epoxied to copper without damage. Wish me luck. I need to reposition the Led's. The epoxy is kinda thin since I sprinkled diamond dust in it.

greg

"1 watt" Luxeon when used "as directed" most typically consumes 1.2 watts. The latest white ones that I know of supposedly typically produce

The "3 watt" white ones in comparison with the more typical 700 mA drive current typically consume 2.6-2.7 watts and produce 65 lumens of light when doing so when cooled sufficiently to have their chip junction temperature 25 degrees C. requiring the surface of the LED's heatsink slug to be cooled to about -9 to -10 degrees C. Expect with temperature 40 degrees C warmer, light output to be about 14% less. 80 lumens is typically achievable from white "Luxeon III" at 1 amp, with typical voltage drop 3.9 volts so power consumption would typically be 3.9 watts. Again, this is with cooling sufficient to have the junction within the chip at a temperature of 25 degrees C, and the heatsink slug surface of the LED needing to be cooled to about -25 degrees C to achieve that. At 50 degrees C warmer than that, expect light output about 18% less.

Based on how I see the DS25 and DS45 datasheets from Lumileds...

- Don Klipstein ( snipped-for-privacy@misty.com)

They do exist, not for all colors, and price increases more than performance for most applications.

Keep in mind that 3W Luxeon has same chip size as 1W but 5W has a 2x2 array of same size chips - making any collimated beam up to twice as wide (or twice as blurry).

- Don Klipstein ( snipped-for-privacy@misty.com)

haha, well, good luck! =) why are you removing them again?

Jason

Thanks for the info Don. Hmmm, these things are starting to remind me of the charging of bloody SLA batteries when you talk about temperature and heatsinks and stuff! Jaycar Electronics have got these 'Heatsink Pin Grid Array with adhesive thermal transfer tape' (CAT HH-8580). These wouldn't be sufficient for 3W stars? Its says it has a thermal resistance of 5.9 degrees celcius per watt. If not, what if I add a small cooling fan as well? Trouble is, all of this needs to fit into an ABS box (will be ventilated of course) size approx 83L x 54W x 31D, but all the electronics will be in another box close by. What do you suggest? I've never used these things before.

Regards Jason.

I have them currently spaced so there is no clearance between them. I am going to use fiber optic to couple 9 into 1 light source. I also use a peltier devive to pump heat out faster from the Led's, and from the copper to aluminum CPU heatsink and fan.

greg

LXHL-PM02

I need 9 or 10 of these ASAP. ???

I tried taking the things off the sink. Amazing the way they are made. I tried heating the sink to 150 F so the epoxy stuff softems. Well everything softens. The metal bottom piece is attached to a wafer with some kind of glue or epoxy. Some kind of sparkly stuff also, which looked like dimonds, but I believe there is no electrical insulation between the wafer and sink. This little sink is mated with the larger aluminum sink sold as a star. With the little sink and attached wafer on the bottom, a gel like material in between the wafer and top clear plastic envelope. The connections are made and a plastic outer rim is then attached.

I have a 6 week 50 min order to make unless I can find a interim supplier.

greg