Chapter 1, page 11 This code is basic but allows the reader to gain insight into key elements for several other projects in this book. It combines two pieces of code that are listed in the examples ...

They're 12v so the arduino powers one lead at 5v for the signal, the ground is shared between the 5v and 12v, and finally the LED's are driven by a 12v source separate from the arduino (12v x 2a ...