What Is a Circuit Diagram?

A circuit diagram, known also as an electrical diagram or an electronic schematic, graphically represents an electrical circuit. A circuit is a pathway, connecting a group of electric or electronic devices with conductors. The diagram in electrical systems and components show a map of the path and the return of electrical circuits. Pictorial maps, common for the layman's use, display simple and recognizable images, such as a broken line for a switch or straight line for a wire. Schematic maps, often used by more advanced professionals, display the more complex industry standard symbols depicting amperes or terminals or other electric components.

Circuit diagrams are important as they illustrate the exact plan and path of the desired electrical circuit. Unlike a simple layout or wiring diagram, they do not display the physical arrangements of the circuit but rather the basic circuit or wire connections of electrical components within the electronic device. Professionals construct electronics, build electrical systems and maintain such systems with an electrical diagram as their guide. These diagrams are identified according to their purpose: amplified circuit diagram, electronic circuit diagram, power circuit diagram and power supply diagram, to name a few.

As electric technology has changed, so have circuit diagrams. Old electronics such as radios and other devices were once boxes housing a twisted network of wires connected to internal conductors. Today, plastic circuit boards contain small grooves or mapped surfaces to direct narrow metallic pathways, called traces, to the conductors inside the electronic device. While the same basic concept remains — that of pathways connecting conductors — circuit diagrams have evolved to reflect the more complicated mappings and additions to modern electronics and electrical systems.

At one time, the circuit diagram symbols varied according to country of origin, but the symbols are now globally standardized. As the nature and technology of electronics have progressed, so have the diagrams and their symbols. For example, when the resistor was commonly used as a coil and wound so as not to produce inductance, the symbol for the resistor was a jagged, zig-zag line. Today, the resistor is no longer used in such a manner but is symbolized as an oblong shape with the numerical value of ohms — the units of resistance — written inside to represent its use as a metal-coated chip or tube.

With the increase of electronics in typical everyday items such as coffeemakers, vehicles, dishwashers, these diagrams have become a type of instructional tool and resource for repairing electronic devices. The diagram illustrates the path of electrical continuity. While it can appear complicated with its vast use of symbols, this diagram is simply a map displaying the path and connections of a circular route of electricity — the circuit.