This instructable will show you who to build a rgb lighting system with an arduino. You can also control it with an ipod/iphone/ipad using touchOSC. In my previous instructable I showed how to control one rgb led in this you can control heaps with a single chip the ULN2003A.
Step 1: Parts
You will need
Arduino
ULN2003A ic or equivilent
common cathode RGB LED’s(- + – -)
jumper wires
breadboard or perfboard
Resistors based on your led(I used one per channel)
Cable for linking RGB LED’s around your home(optional)
Step 2: The circuit
Red to pin 9
green to pin 10
blue to pin 11
Step 3: Program

There are two sets of code bellow one is a simple flash red, flash green, flash blue and is my code.The other is ipod controlled with aduino IDE and processing code it requires the oscpc5 processing library and is ipod/iphone/ipad controlled using touchOSC.
ULN2003A ic or equivilent
common cathode RGB LED’s
For more detail: Arduino mood lighting