Circuit Theory

A NOT Logic Gate turns a TRUE signal into a FALSE signal. Let’s take the case of the ordinary household light switch: When you flip the light switch in your home UP, the light bulb turns on. Now, let’s mount the house light switch upside down. When you send an UP signal to the switch, the light bulb will turn off. When you send a DOWN signal to the switch, the light bulb turns on. To illustrate this basic FALSE-TRUE operation, Figure 5-2 shows a simple NOT Logic Gate circuit you can build and experiment with, using a few electronic components. After wiring the NOT Logic Gate circuit on the breadboard, the red LED will be on. Pressing the pushbutton switch will turn the red LED off.

Figure 5-2. A simple NOT Logic Gate Fritzing wiring diagram