Step 1: RGB LED Internal Diagram
You can see that pin 2 is the three internal LEDs negative lead or cathode and 1, 3 and 4 are each of their respective positive leads or anodes. We are going to physically control the RGB LED by making Bare Paint Potentiometers for each of its positive leads instead of using static resistors. Thus by altering the resistance we will ultimately change the current flowing into each diode and affect its brightness. This is a fairly crude way to control LEDs. There is a more elegant way to do this using an Arduino and PWM (pulse width modulation). We will cover this in another tutorial.