I bought 20 3W RGB LED's the other day, and wired them all up on a 7mm piece of aluminium. Each colour is controlled by a FET, and by an Arduino (For now). I play to build it into a box and add DMX control with an ATMega. This thing draws around 21A @ 3.3V! I am using a computer power supply to power them at the moment.
This thing is BRIGHT!
That last image was in broad daylight. At night, you dont even need any lights on, this lights the room in any colour you want! 
Very Nice. I just have 1 3W RGB LED and it is quite bright.
You might want to put some kind of diffusor over your LED-Array
so you dont get blinded if you look at them.
There is a power supply at Electronc-Goldmine that would work well for
this type of application. It is a Vicor VI-LU0-EU FlatPAC which ouputs 40A at 5V.
The output is trimable to 0.5V. You could adjust the output to 3.3V or to 4V if you
use higher Vf LEDs. The price is $40. 1MHz switcher. Very compact.
The usual caveats about purchasing surplus apply.
(* jcl *)
I was going to buy it, but they only have shipping methods to the US 
So I would have to pay to ship it to someone in the US, then pay for shipping from them to me. I know a few people that will do it, dunno if I have enough money at the moment though.
Good suggestion though 
That's surprising that they won't ship international. It's not difficult to setup.
There's also a $5 off of $40 coupon in the flyer.
Pics of my LED current sink design are at Loading...
Four channels, 10A per channel, programmable currents, FET output.
(* jcl *)
That's a LOT of light. What is your plan for this beast?
You should run the LEDs in series rather than parallel. You'll have better control over them and use less amperage, which will be safer too. Also, power LEDs MUST be driven with a constant current driver or they can thermal runaway and cook very easily. (The hotter they get, the more current they draw, the hotter they get, ad destructum).
EDIT: Gaaa! Common cathode. Never mind the series suggestion.
Yeah, I was considering putting them in series, but they are common anode (Labelling is misleading).
As for current limiting, they don't seem to mind if I keep to the right voltage.
Where did you get your 3W LEDs from? I might be doing a project for a class where I will need bright LEDs.
http://www.dealextreme.com/details.dx/sku.4530
Also, I have the DMX receiving code working nicely.
Thanks for the link; it will be appreciated for my class.
Cool! Are you using the Arduino DMX library?
As for current limiting, they don't seem to mind if I keep to the right voltage.
Famous last words. 
Most good examples of running these kinds of 3 watt LEDs use full constant current drivers rather then simple current limiting resistors. Using no current control, just voltage drive is pretty risky.
Lefty
This is something I would like to do.
I'm very new though could you discuss some considerations with regards to this kind of setup?
#1, Do these lights get hot? is a heat sink needed? (according to the ones you're using)
#2 what is meant by common cathode or anode?
#3 how does one setup a current driver?
I would like to do this but don't want to burn anything up in the process so any help would be appreciated. Thanks
#1, Do these lights get hot? is a heat sink needed? (according to the ones you're using)
Well, seeing as there is 60 Watts of power, yeah, I'd say it's necessary. High power LEDs burn out very quickly if they're not attached to an appropriate heat sink.
#2 what is meant by common cathode or anode?
Common Cathode means that all the LEDs' Cathodes (negative leads) are connected, and Common Anode means that all the LEDs' Anodes (positive leads) are connected.
Well, seeing as there is 60 Watts of power, yeah, I'd say it's necessary. High power LEDs burn out very quickly if they're not attached to an appropriate heat sink.
What kind of heat sink would I need?
What kind of heat sink would I need?
A big one.
Read up about power dissipation:-
The "heatsink" I use for this array is just a peice of 1cm thick aluminium. It seems to keep it cool enough, though I haven't run it from extended periods of time.
Nice project! It is extremely bright too! 
I hope you don't mind the spam, but I built a shield for handling power LEDs. It makes for very easy LED projects and helps prevent LED and Arduino destruction .
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1258412419/all#all
i love this project and i want to make something similar to this however i dont know how to power up these leds, does anyone know if its safe to use a computer power source? i read that these leds are constant current driven and not voltage driven.... :-[ whats the best way to power up 2 rgb leds in parallel?
Quote:
As for current limiting, they don't seem to mind if I keep to the right voltage.Famous last words. Wink Most good examples of running these kinds of 3 watt LEDs use full constant current drivers rather then simple current limiting resistors. Using no current control, just voltage drive is pretty risky.
Lefty
Is this still running?
I am looking to run RGB LEDs -the clear 4 wire ines in a similar fashion. Any reason this would not work?