The Arduino NOT Logic Gate
Computers use electrical signals to make basic decisions. By hard-wiring electric circuits in specific ways, you can actually see simple logic decision operations at work. Ordinary electronic parts, like electrical switches, resistors, and LEDs can make AND, OR, and NOT logic gates when wired together properly.
The first computer logic decision circuit you will build is a NOT gate. You will also learn how the Opposite Switch works in electrical/electronic and digital computer circuits by building an Arduino NOT Logic Gate. Figure 5-1 shows the Arduino NOT Logic Gate (the Opposite Switch) device.