As the name implies, inverter will invert the number entered. If you enter ”0“, you will get a ”1“ on its output, and if you enter a ”1“, you will get a ”0“ on its output. The inverter symbol you can see in Figure 1. Inverter gate is also known as NOT and its output is Y = /A.

Figure 1: Inverter.

On the truth table below you can see a summary of how this circuit works.

A (Input)	Y (Output)
0	1
1	0

On logic circuits, a ”o“ symbol is a short for inverter. You will see that on logic gates like NAND, NOR and XNOR.

The most famous inverter integrated circuit is 7404 and you see its pinout in Figure 2. It has six inverters inside. To make this integrated circuit work, you need to connect it to a 5 V power supply.

click to enlarge
Figure 2: 7404 integrated circuit provides six inverters.