Electronic symbol

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Common circuit diagram symbols (US symbols)

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.

Standards for symbols[edit]

The graphic symbols used for electrical components in circuit diagrams are covered by national and international standards, in particular:

  • IEC 60617 (also known as British Standard BS 3939).
  • There is also IEC 61131-3 – for ladder-logic symbols.
  • JIC JIC (Joint Industrial Council) symbols as approved and adopted by the NMTBA (National Machine Tool Builders Association). They have been extracted from the Appendix of the NMTBA Specification EGPl-1967.
  • ANSI Y32.2-1975 (also known as IEEE Std 315-1975[1] or CSA Z99-1975).
  • IEEE Std 91/91a: graphic symbols for logic functions (used in digital electronics). It is referenced in ANSI Y32.2/IEEE Std 315.
  • Australian Standard AS 1102 (based on a slightly modified version of IEC 60617; withdrawn without replacement with a recommendation to use IEC 60617).

The number of standards leads to confusion and errors.[2] Symbols usage is sometimes unique 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.

Common electronic symbols[edit]

Symbols shown are typical examples, not a complete list.[3][4]

Traces[edit]

The large dot signifies an electrical connection.

Grounds[edit]

The shorthand for ground is GND. Optionally, the triangle in the middle symbol may be filled in.

Sources[edit]

Resistors[edit]

It is very common for potentiometer and rheostat symbols to be used for many types of variable resistors, including trimmers.

Capacitors[edit]

Diodes[edit]

Optionally, the triangle in these symbols may be filled in. There are multiple ways to draw a bridge rectifier symbol.

Bridge rectifiers[edit]

There are many ways to draw a single-phase bridge rectifier symbol. Some show the internal diode circuit, some don't.

Inductors[edit]

Transformers[edit]

Transistors[edit]

Unipolar[edit]

Optionally, these symbols may include a circle.[6]

Bipolar[edit]

Optionally, these symbols may include a circle.

Vacuum tubes[edit]

Switches[edit]

Relays[edit]

Lamps[edit]

LED is located in diode section.

Current limiters[edit]

Electro-acoustic devices[edit]

Antennas[edit]

Connectors[edit]

ICs[edit]

Logic gates[edit]

For the symbols below: A and B are inputs, Q is output.

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 Q output too.

The above logic symbols may have additional I/O variations too: 1) schmitt trigger input(s), 2) tri-state output, 3) open-collector or open-drain output (not shown).

Flip-flops[edit]

For the symbols below: Q is output, Q 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, Q only, both Q & Q); 2) one or both forced inputs along top & bottom (R only, S only, both R & S); 3) some inputs may be inverted.

OpAmps[edit]

Oscillators[edit]

Miscellaneous devices[edit]

Historical electronic symbols[edit]

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.

Capacitors (historical)[edit]

All of the following are obsolete capacitor symbols.

See also[edit]

References[edit]

  1. ^ "IEEE Standard American National Standard Canadian Standard Graphic Symbols for Electrical and Electronics Diagrams (Including Reference Designation Letters)," in IEEE Std 315-1975 (Reaffirmed 1993) , vol., no., pp.i-244, 1993, doi: 10.1109/IEEESTD.1993.93397.
  2. ^ Guidelines for Drawing Schematics.
  3. ^ Circuit Symbols for all Electronic Components. Talking Electronics, 2013. Retrieved 01 Apr 2015.
  4. ^ Electrical Symbols & Electronic Symbols. RapidTables, 2012. Retrieved 17 April 2016.
  5. ^ "Standards for Resistor Symbols". eePower. EETech Media. Retrieved September 13, 2021.
  6. ^ "A4.11 Envelope or Enclosure". ANSI Y32.2-1975 (PDF). The envelope or enclosure symbol may be omitted from a symbol referencing this paragraph, where confusion would not result

Further reading[edit]

External links[edit]