Circuit symbols

from Wikipedia, the free encyclopedia
Circuit symbols in the USA. Links for electrical circuits. Right for logical interconnection.

A circuit symbol is a standardized, graphic symbol used in a circuit diagram in electrical engineering for components , components, device parts, devices and lines within an electrical circuit . With such a circuit symbol, the circuit can be created more easily and recorded much faster. Another area of ​​application is the representation of equivalent circuit diagrams .


In Germany, electrical circuit symbols are standardized by DIN EN 60617 graphic symbols for circuit diagrams or IEC 60617 . Since 1996–1998 they have replaced DIN 40700 / DIN 40900.

In relation to the IEC numbers, a new, 5-digit system (number range from 60000–69999) has been used since the beginning of 1997. The advantage is that in the future international, European and national standards will have the same number. Older designation such as B. IEC 617 will be specified as IEC 60617 after new editions or revisions, i.e. that is, 60,000 is added to the original number. The 5-digit number will also be found for reference information - even if a revision has not yet taken place.

In North America, the standards ANSI / IEEE Std 91a – 1991 IEEE Graphic Symbols for Logic Functions , IEEE Std 315–1986 (Reaffirmed 1993) / ANSI Y32.2–1975 (Reaffirmed 1989) / CSA Z99–1975 Graphic Symbols for Electrical and Electronics Diagrams and NEMA Standards Publication ICS 19–2002 Industrial Control and Systems: Diagrams, Device Designations, and Symbols in Use.

Origin, symbolism of components

Many electrical symbols are based on the mechanical, geometric or electrical structure of the components.

  • Line connections can be formed by a drop of solidified solder or a screw terminal (= thick point)
  • Connections are often screw connections with a visible screw head (= small, delicate circle)
  • The first diodes consisted of a (semiconductor) crystal, on the surface (= line) of which a metal needle with its tip (= triangle) was pressed.
  • Electron tubes are typically sealed in cylindrical glass tubes (= oval), the indirectly heated cathode lies against the heating loop in an arc shape, grids appear in cross section as (=) broken lines.
  • Transistors were initially enclosed in small glass tubes (= circle). In German circuit diagrams labeled with T1, T2, ..., in Japanese (around 1980) and US, however, with Q1, ...
  • Coils, inductances work through a cylindrical winding (oblique view = chain of U-bends (USA) or (D :) loops or as an elongated black square)
  • The ferromagnetic core of a coil is added to the symbol as an accompanying straight line. If there is another symbol for coil next to it, a transformer is symbolized. Winding taps are brought out as cross lines.
  • The push button of a button and the connection of mechanically coupled switches, also in relays, are represented by delicate lines or double lines (= isolator).
  • The ground line of a circuit is often shown as the bottom horizontal line, sometimes in bold; Ground connections, roughly similar to the housing; Earth connections through a short line to a bold horizontal line, with horizontal (getting shorter, forming an arrow triangle downwards) or diagonal hatching below.
  • The simple antenna is an up arrow. Folded and closed dipoles are symbolized geometrically accordingly.
  • A variable capacitor is often a variable capacitor, sometimes shown in the US version as a horizontal line (= plate (s)) plus a curved line (= rotatable).
  • The shielding of a cable is shown as a dashed circular line at any point on the conductor (= braided network in a cable construction)
  • An oscillating quartz is drawn as a small rectangle between two bold horizontal lines.
  • Plug connections are shown for each contact as a bold line (= pin) and a matching delicate U (= socket).
  • As a circuit diagram, an electric motor shows a circle (= rotor) and opposite small fat rectangles (= magnetic coils).


See also

General symbols:

Special symbols:

Web links

Commons : Electrical and Electronic Diagrams  - collection of images, videos, and audio files
Wiktionary: components  - explanations of meanings, word origins, synonyms, translations