The NOT, AND, and OR projects (Chapters 5, 6, and 7, respectively) use two basic voltages: either +5VDC for TRUE or 0V for FALSE. These two signals let the Arduino make basic logic decisions. In the computer world, these voltages are known as binary data. In computers, binary data is represented by logic “1” (+5 volts DC) and logic “0” (0 volts). You can build a cool electronic device to see binary data using a few electronic components. The electronic components to build this device are shown in the Parts List. The Logic Tester with an RGB LED is shown in Figure 15-1.