Three Kinds of Diagramme

You'll encounter three types of diagrams in electricity and electronics literature. Each style serves a unique purpose. When you buy an electric or electronic device or system, it should (in the ideal case) come with an operating and maintenance manual that includes all three types of diagrams.

1. A block diagram gives you an overview of how the individual circuits in a system work together. You'll see each circuit represented as a

   block

   (rectangle or other shape, depending on the application). Interconnecting lines, sometimes with arrows on one or both ends, show how the circuits combine to form the whole system, and how currents and signals flow among those circuits.
2. A schematic diagram (often simply called a schematic) shows every component in a circuit. Each component has its own special symbol. Lines between the components reveal how they connect together, and to a source of power, so they perform a specific function or operation.
3. A pictorial diagram (sometimes called a layout diagram) shows the physical arrangement of the components on a circuit board or chassis so you can identify them for installation, testing, or replacement. Some such “diagrams” are actual photographs. Keep in mind, however, that pictures rarely reveal the electrical events that occur in a circuit or system.