74HC595 Shift Register

74HC595

Image Courtesy of Adafruit

Use a shift register to additional digital outputs to your Arduino.  Shift 8 bits serially into the shift register and output them in parallel. You can daisy-chain shift registers together add even more outputs.

Download the 74HC595 Shift Register Datasheet (PDF)

Buy the 74HC595 Shift Register from SparkFun, Adafruit, or Newark.