Any one care to help with a design for rgb led room lighting with an arduino?

Hello everyone!
I had this awesome idea after seeing dan's instructable about his room lighting module. My idea was to do basically the same thing with the Arduino Duemilanove  instead. But it turns out that this maybe a little trickier than my initial thought.

What i had in mind was having 10 rgb leds(common cathode) connected in parallel(each red, green, and blue) and connect each to one of the Arduino's pwm pins and using software to control the "fading" of the different colors.

The only problem i could think of with this is that the Arduino could not power more than a few leds in parallel without them either being dim or blowing the atmega on the board. Maybe there's a way to control the leds with an outside power supply, and still be able to pwm the different channels. This is where my few hours of research and not finding anything has led me here to ask help from someone who has some more experience than i.

So if anyone has any way to do this other than using rgb amps, please help me out and share with me your info. Thanks in advance for any help i get.

Comments

[usLEDsupply]

for running small leds like those from an Arduino i would just use a Darlington Transistor Array tho you may want to get the common anode ones, you will also need a lot of resistors (one for each color on each led)

depending what you are trying to light you may want to look at led strip or RGB modules as they will be easier to use and have much better light output and color mixing

This is what i would do as it only costs a few dollars and is quite simple
http://fritzing.org/projects/arduino-knight-rider-with-8-blue-12v-led-modules/

if you want to connect lots of leds or strips you may want to do something like this
http://fritzing.org/projects/arduino-controlled-rgb-led-light-strips/

[1badrc]

What are you using for V+ into your ULN2803? I didn't see anything powering it in the picture. I am trying to run a series of RGB LED's with my Arduino (common anode) and I am having a heck of a time figuring out how to get everything working.

[belliedroot]

You use either power mosfets or transistors to handle the load, that way the arduino is only switching the transistors or mosfets on and off. There is lots of info on this here and on the interwebs using transistors or mosfets with microcontrollers. One quick tip is if you use a separate power supply is to make sure you connect the ground from the separate power supply to the arduino even if the arduino is using it's own power supply.