# What Is a Schematic Diagram?

Mark Wollacott
Mark Wollacott

A schematic diagram is a simplified representation of a system. Such schematics are often not to scale and use symbols rather than realistic images. Their purpose is to explain how a system is organized and how it works.

There are many examples of schematic diagrams encountered daily. The most common schematic diagram is found in large cities as the subway map. Across the world, car and motorbike owners use instruction manuals heavily dependent on such diagrams in order to repair their vehicles. Schematics are also used to illustrate chemical processes, wiring, plumbing and electronic circuits.

Schematic diagrams work because they provide an uncluttered illustration of how a system works. The use of spaces highlights a system’s organization rather than wasting space with unnecessary information. They are usually unrealistic because component relationships are easier to understand. A good schematic diagram will space out elements contained within, thus keeping functions and connections distinct from one another. It also uses exact values and quantities, all of which, if vital, are labeled on the diagram; due to the use of symbols within the diagram, they are often accompanied by a key.

There are other rules to a schematic diagram, too. Taking electronic circuits schematics as an example, there are conventions that are usually followed. Many diagrams of different circuits will incorporate a set symbol system. By keeping symbols consistent, users will gain a larger degree of familiarity with circuit layouts.

In a circuit schematic, wires sometimes connect with one another and they sometimes overlap. In order to distinguish between the two, a round, black dot is used illustrate a connection. If two wires cross on a diagram and there is no dot, then it is safe to assume they do not connect.

Furthermore, if there is a short lead between a component and a connection, the scale of the lead is exaggerated. This provides extra space for the brain to interpret. By doing this, the separation of the component and the connection are made clearer.

For the sake of aiding comprehension and troubleshooting, symbols used within a schematic diagram tend to be either horizontal or vertical. The use of consistent angling adds a sense of order to the diagram, which also aids the brain’s interpretation of the system. This is not an absolute law of schematics; if a schematic truly needs all sorts of angles, they should still be used.