Luxeon Star/O review

http://www.bit-tech.net/review/82

Let's talk about it...

 

They look awsome and look to offer serious competition to CCFLs.
I think I will be using some as soon as I can see again!
They are bright!

 

I WANT!!!!! NO NEEEEEEEEEEEEEEEEEEEEEEEEEED!!!

 

hey, when i posted about them a while ago, everyone told me to get some of those diheltro bulb thingies. but once linear touches them they are gold. i see how it is *grumbles*.....

 

Would these be bright enough to light up 1' of sideglow FO cable?

For the lighted fan mod I want to do a clear fan, but instead of points of light I would like to have sideglow cable along the blade to make a panel of light instead of circles. I was wondering if like the white style of these (180Cd) was enough to light up enough sideglow to do a fan? (I think I would need enough light to do a foot or two)

 

Heh, I was working on sourcing the things already when I saw your post--I didn't want to jump in and defend you even though I knew you were on to a real hottie, because I wanted to break the news to the world myself don't you know...

FWIW, those dichroic bulbs are dissipating 20W while this amazing LED dissipates slightly over 1W (350 mA * 2.95 V), a little more in blue.

 

Thats got some amasing power for the wattage it uses.

 

yeah i've read about these a while ago on the candlepowerforums. i always wanted one but with no electronics experience, i wouldnt know how to wire one up anyways. so from the red (+5v) wire on the molex connector i just wire five 33 Ohm, 1/4 Watt resistors in parallel and connect to the luxeon star, then wire to the black (gnd) right? yes i'm a total n00b.

 

lol linear kind of stole his fire

although not properly

anyway, they are dam nice, although I dont like the idea of looking in my computer and being blinded.

 

Luxeon LEDs

Funny you should mention these LEDs. I have managed to blag a free sample from Luxeon (a white emitter --normally about $12,-- so that was jolly decent of them) for a home application.

My mother's eyesight is failing so I got her a magnifying glass for reading, you know the kind, those big ones that hang around your neck and are perched on your chest while you sit and read. They come with battery powered lightbulbs, the weedy ones you find in cheap torches and can't light for ****. So I decided on a little upgrade. What do we need? MORE POWER! That's right, I am upgrading the bulb to a white Luxeon emitter. Even on 3 Volts (its intended battery power source), which is 75% of its nominal power supply, it left afterimages on my retina. I think it'll do for reading...

Anyway, I'm now looking for a small heatsink-- probably one used for transistors normally. I hope I can use one small enough to be practical (luckily my multimeter has a temperature probe) else I will go back to my original plan of four white 5mm LEDs.

Since I have acquired a digital camera recently, I'm happy to do a short article on the operation and results, if people desire...

 

think i could get this to work in an optical mouse?
im sure it would.

 

but it does generate some heat though ... alot ? or just slight heat ?

 

Now I can see again....

They have some serious power behind them, and look so much neater than a Cold cathode. Will they be doing them in UV?

 

It's big. I don't know how much room there is in your optical mouse, but why not just use a standard T 1-3/4 size LED? I'd worry about overwhelming the detector. This is 100 times brighter than a "high-intensity" LED after all.

Well, about 1W at the rated current. I was underdriving by 20% or so, so mine was dissipating 600 mW or thereabouts (because the voltage drop is not a linear function of current)

I don't know. One of the things the datasheeet mentions as a feature is "no UV output." I would consider a UV light of this intensity fairly dangerous. After all, with the visible light, you reflexively look away to avoid eye damage. If you can't see the UV light (dunno about you, but I can't) you could easily burn up your eyeballs. Not a good thing.

 

Here's a little bit more detail about selecting a resistor:

royal blue, blue, white, cyan and green: Vf = 3.42 V
red, amber, red-orange, Vf = 2.95 V
operating current is 350 mA for all of them

So for the first case
R = (5 - 3.42) / 0.350 = 4.5 ohms
P = (5 - 3.42) * 0.350 = 553 mW

Four 18 ohm resistors in parallel would be a convenient way to get 4.5 ohms. Using standard 1/4W resistors would be just fine. the combination would handle the 553 mW power dissipation with no problem.

And the second case
R = (5 - 2.95) / 0.350 = 5.9 ohms
P = (5 - 2.95) * 0.350 = 718 mW

A little trickier to hit this one on the nose. The closest match using equal resistors with standard values would be two 12 ohm resistors in parallel for 6.0 ohms, but you'd need to use 1/2 W resistors to handle the 718 mW you need to dissipate.

I used five 33 ohm resistors in parallel, which is quite conservative at 6.6 ohms.

To get the value to two significant digits, you'll need to combine unequal standard value resistors in parallel. I think the best choice is:

three 22 ohms and one 33 ohm in parallel: 6.0 ohms
the 22 ohm resistors will dissipate (2.05^2 / 22) = 191 mW each, that's ok.

 

To Detn8r, BiGGie and Cyberdome:

The actual emitter is no larger than a 5mm LED (the one featured in Bit-Tech comes in a special housing). Nevertheless, it does get a bit hot... without heatsink about 70 degrees Centigrade, apparently, but I still have to test that. Don't know why you'd want to build one into an optical mouse though. I mean, it's BRIGHT. Don't know whether you'd just end up blinding the camera. And do you really want a mouse that looks like a small spaceship about to take off from your desk? Wait-- stupid question, of course you do!



About UV leds: this is actually quite tricky. Going into the UV spectrum means shorter wavelenght, as you know, thus more energy is required to excite the phosphorous material in the die (the little tiny cube at the center of the LED that glows). Some Japanese company (and it would be them, wouldn't it?) have made some standard 5mm UV LEDS, and even some purple ones, but don't expect Luxeons just yet. Even the purple ones, cool as they look, should not be stared into directly at close range. UV Luxeons, when not used for industry purposes, would just be a very effective way to get blind. Find more info at
http://ledmuseum.home.att.net/

 

I think what I will do is cut a hole in the top of my case, and then put the staro on top, so it creates like a beacon of hope for all I just wish I could get an actual feeling of how bright these things are, cuz Im pretty sure the pictures arent doing them justice

 

You're right. The camera can't adequately convey the impression. It just overloads since no camera has the dynamic range of the human eye.

You will see spots looking at these. Your reflexes will prevent you from looking directly at one for very long.

On the other hand, the beam is collimated, so looking off-axis you'll drop off very quickly in brightness.about 30-40 degrees off axis you can look directly at one of these, it gets uncomfortable less than that.

 

Hey Linear,
I would like to know if you could post a pic of the blue or white Star/O with all the resistors hooked up. Im trying to figure out how to set one up in my pc. What would be the best way. It seems like with all the components I need a special way of laying it all out.
I read your thread and it is very informative but I'm one of those visual types.
Thanks for any help.

M

 

Code:

       +--/\/\/\--+
       +--/\/\/\--+
+5V o--+          +--|>|--o ground
       +--/\/\/\--+
       +--/\/\/\--+
    

Four 18 ohm 1/4W resistors in parallel, the combination making 4.5 ohms. Connected in series with the LED itself and +5V (Not 12V!).

That will drive your Blue or White LED at 350 mA.