circuit diagram

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A circuit diagram (also circuit diagram or circuit sketch ) is a graphic representation of an electrical circuit that is commonly used in electronics . It does not take into account the real shape and arrangement of the components, but is an abstract representation of the functions in the form of defined symbols for the individual components and their electrical interconnection. Related to it and used in the field of electrical engineering and electrical installation technology is the circuit diagram .

Circuit diagram of an operational amplifier

In addition to the general informative presentation, a circuit diagram also serves the following purposes:

  1. As a preliminary stage for the layout design of printed circuit boards . The components housed on a circuit board and their interconnection are first drawn in the circuit diagram and so-called net lists are created for the layout. CAD programs such as KiCad serve this purpose .
  2. In a modified form as a preliminary stage for the design of mostly simple integrated circuits . With complex integrated circuits, graphic representations are too large and confusing. Complex integrated circuits are accordingly modeled using hardware description languages .
  3. As input in a circuit simulation to check a certain function before the concrete implementation or to optimize the parameters of the components and adapt them to certain requirements. One program for this use is, for example, PSpice .


Line crossings in circuit diagrams:
Column a: Fixed conductive connections
Column b: Contactless encounters
Line 1: Earlier, outdated representation
Line 2: Currently valid representation
Line 3: Junctions (instead of intersections)

Standardized circuit symbols are mostly used in circuit diagrams , but not consistently. The graphic symbols are defined in the internationally agreed standard IEC 60617, which is mainly used in Europe. In North America, forms of representation based on the ANSI standard Y32 ( IEEE Standard 315) are common. A typical symbol that is represented differently is, for example, the electrical resistance , which is represented as a rectangle according to the IEC standard and as a zigzag line according to the ANSI standard.

Lines indicate conductive connections between components in circuit diagrams. In the case of intersecting lines, a distinction must be made as to whether the connections come into contact with one another or whether they only meet on paper and remain in the circuit without contact. This is explained further in the picture opposite.

In the case of components, a designation system is added where necessary, in which each component is given a unique designation ( reference designator ). This data is required , among other things, for the creation of the parts list and assembly plans in the course of production.

Circuit diagrams in electronic form often contain, in addition to the graphical representation, other non-graphical information in the form of parameters and attributes. These can describe electrical parameters of the connecting lines between the components, for example minimum or maximum conductor track thicknesses on the circuit board and their distances from one another or certain line wave resistances . For the individual components, specific manufacturer names, order numbers or warehouse numbers can also be stored in the circuit diagram.

The printed circuit board derived from the circuit diagram is often assembled in several variants within the framework of production and use in various electronic devices. Which components are to be fitted per variant is also information that is usually recorded in the circuit diagram.

If the content of the circuit diagram is to be simulated, the circuit diagram contains special information about the type of simulation.


  • Moeller basics of electrical engineering. 21st edition. Vieweg + Teubner, Wiesbaden 2008, ISBN 978-3-8351-0109-8 .
  • Jens Lienig, Hans Brümmer: Electronic device technology. Basics for developing electronic assemblies and devices. Springer Verlag, Berlin / Heidelberg 2014, ISBN 978-3-642-40961-5 .
  • Günter Kemnitz: Technical computer science . Volume 1: Electronics. Springer Verlag, Berlin / Heidelberg 2009, ISBN 978-3-540-87840-7 .

See also


  • Standard IEC 60617, identical to DIN EN 60617 and to British Standards BS 3939
  • ANSI Y32 standard, identical to IEEE standard 315

Web links

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