Any robot relies on electronics to control its parts, relay data, and basically define and handle its function. Electronic modules are practically electrical circuits of varying complexity, interacting with each other at certain levels. Electrical circuits are based on diagrams, which are graphical representations that specify physical components required for the circuit to perform certain functions. Electrical symbols are used as abstract representations of physical electronic components that are used in the circuit, and each such representation should be simple in order to be recognized in any circumstances with no ambiguity. These circuit diagrams are not only useful in prototyping circuits, they can also be a great help in understanding and detecting errors that may occur in the circuit operation.
In time graphic representations of the physical components were standardized, each of these symbols having a certain logic behind its design. This compendium does not aim at exhaustively covering every possible component and representation, it should rather provide a pretty good coverage of the most common electronic components employed in robotic electronic circuitry, and maybe familiarize the reader with electrical schematic symbols and their purpose. Below you can find electrical symbols for common components, logic gate symbols as well as brief explanations of each element. This article is under continuous development.
Physical component representations
Electrical symbols corresponding to physical components in circuit diagrams.
AC current (source)
Light-emitting diode (LED)
Integrated circuit (IC)
Positive voltage connection
Bipolar NPN transistor
Bipolar PNP transistor
Logic gates are basically integrated circuits — silicon chips — containing a small number of transistors used to perform certain logical operations (Boolean functions) on signal — i.e. combine signals with respect to certain rules. Below are some electrical symbols used for representing such components.