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 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  • Australian Standard AS 1102 (based on a slightly modified version of IEC 60617; withdrawn without replacement with a recommendation to use IEC 60617).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.[1] 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.[2][3]



Optionally, the triangle in the following symbol may be filled in.



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



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





Optionally, these symbols may include a circle.


Optionally, these symbols may include a circle.

Vacuum tubes[edit]




Current limiters[edit]

Electro-acoustic devices[edit]




Miscellaneous devices[edit]

Historical electronic symbols[edit]

The shape of electronic symbols have changed over time. Some symbols were more prevalent in some countries. The following are historic electronic symbols that might be found in old electronic books and schematics.

Capacitors (historical)[edit]

See also[edit]


  1. ^ Guidelines for Drawing Schematics.
  2. ^ Circuit Symbols for all Electronic Components. Talking Electronics, 2013. Retrieved 01 Apr 2015.
  3. ^ Electrical Symbols & Electronic Symbols. RapidTables, 2012. Retrieved 17 April 2016.

Further reading[edit]

  • Beginner's Guide to Reading Schematics; 4th Ed; Stan Gibilisco; McGraw-Hill, 224 pages; 2018; ISBN 978-1260031119.
  • How to Read Electronic Circuit Diagrams; 2nd Ed; Brown, Lawrence, Whitson; Tab Books; 214 pages; 1988; ISBN 978-0830628803.
  • How to Read Schematic Diagrams; 4th Ed; Donald Herrington; Sams Publishing; 160 pages; 1986; ISBN 978-0672224577. (2nd Ed in 1973)

External links[edit]