NOT logic gate, diagram. Logic gates are electrical circuits that are wired so as to produce a specific output according to logical rules. The diagram shows an input (A) and an output (Q). A NOT gate has one input. It will output the opposite of this, as shown in the table at lower right. The input here is on, with the LED (light-emitting diode) at right in the off (unlit) state. The shape of the logic gate shown here is that of the NOT symbol used on circuit diagrams. For a series of diagrams of the seven basic logic gates (NOT, OR, AND, NOR, NAND, XOR and XNOR), see images C045/9800 to C045/9806.