An electronic symbol is a pictogram used to represent various electrical and electronic devices or functions, such as wires, batteries, resistors, and transistors, in a schematic diagram of an electrical or electronic circuit. These symbols are largely standardized internationally today, but may vary from country to country, or engineering discipline, based on traditional conventions.
The graphic symbols used for electrical components in circuit diagrams are covered by national and international standards, in particular:
The standards do not all agree, and use of unusual (even if standardized) symbols can lead to confusion and errors.[2] Symbols usage is sometimes idiosyncratic to engineering disciplines, and national or local variations to international standards exist. For example, lighting and power symbols used as part of architectural drawings may be different from symbols for devices used in electronics.
Symbols shown are typical examples, not a complete list.[3] [4]
The shorthand for ground is GND. Optionally, the triangle in the middle symbol may be filled in.
See also: Resistor. It is very common for potentiometer and rheostat symbols to be used for many types of variable resistors and trimmers.
See also: Capacitor.
See also: Diode. Optionally, the triangle in these symbols may be filled in. Note: The words anode and cathode typically aren't part of the diode symbols.
See also: Diode bridge. There are many ways to draw a single-phase bridge rectifier symbol. Some show the internal diode circuit, some don't.
See also: Inductor. An inductor can be drawn either as a series of loops, or series of half-circles.
See also: Transformer.
See also: Transistor. Optionally, transistor symbols may include a circle.[5] Note: The pin letters B/C/E and G/D/S aren't part of the transistor symbols.
See also: Bipolar junction transistor.
See also: Field-effect transistor.
See also: Vacuum tube.
See also: Switch. For multiple pole switches, a dotted or dashed line can be included to indicate two or more switch at the same time (see DPST and DPDT examples below).
See also: Relay. Relays symbols are a combination of an inductor symbol and switch symbol.
Note: The pin letters in these symbols aren't part of the standard relay symbol.
LED is located in diode section.
Speaker symbols sometimes include an internal inductor symbol.
See also: Antenna (radio).
See also: Electrical cable.
See also: Electrical connector. There are numerous connector symbol variations.
See also: Integrated circuit.
For the symbols below: A and B are inputs, Q is output. Note: These letters are not part of the symbols.
There are variations of these logic gate symbols. Depending on the IC, the two-input gates below may have: 1) two or more inputs; 2) infrequently some have a second inverted output too.
The above logic symbols may have additional I/O variations too: 1) schmitt trigger inputs, 2) tri-state outputs, 3) open-collector or open-drain outputs (not shown).
See also: Flip-flop (electronics). For the symbols below: Q is output, is inverted output, E is enable input, internal triangle shape is clock input, S is Set, R is Reset (some datasheets use clear (CLR) instead of reset along the bottom).
There are variations of these flip-flop symbols. Depending on the IC, a flip-flop may have: 1) one or both outputs (Q only, only, both Q &); 2) one or both forced inputs along top & bottom (R only, S only, both R & S); 3) some inputs may be inverted.
Note: The outside text isn't part of these symbols.
See also: Electronic oscillator.
The shape of some electronic symbols have changed over time. The following historical electronic symbols can be found in old electronic books / magazines / schematics, and now considered obsolete.
All of the following are obsolete capacitor symbols.