USB color changer overview

LED circuits and resistors

The example light board uses two strings of two green and blue LEDs, and one string of four red LEDs. The red string requires 10 volts, and the green and blue strings need 6.6 volts. A 12-volt supply is perfect for this circuit, with a 220 ohm resistor on the red string and a 270 ohm resistor on the green and blue strings.