Electronic symbol

An electronic symbol is a pictogram used to represent various electrical and electronic devices (such as wires, batteries, resistors, and transistors) in a schematic diagram of an electrical or electronic circuit. These symbols can (because of remaining traditions) vary from country to country, but are today to a large extent internationally standardized. Some symbols represent components (such as vacuum tubes) which ceased to be used routinely as newer technologies were introduced.

Standards for symbols

There are several national and international standards for graphical symbols in circuit diagrams, in particular:

IEC 60617 (also known as British Standard BS 3939)
IEEE Std 91/91a
ANSI standard Y32 (also known as IEEE Std 315)
Australian Standard AS 1102

Different symbols may be used depending on the discipline using the drawing. For example, lighting and power symbols used as part of architectural drawings may be different from symbols for devices used in electronics. National and local variations to international standards also exist.

Gallery of common electronic symbols

Symbols shown are typical examples, not a complete list. ^[1]

Resistors

American-style resistor (a), rheostat (variable resistor) (b), and potentiometer (c)
IEC-style resistor
Thermistor

Capacitors

Capacitor
Capacitor, polarized (American)
Capacitor, variable

Transistors

Diodes

Vacuum tubes

Switches

Switch, Single Pole/Single Throw (SPST)
Switch, Single Pole/Double Throw (SPDT)
Switch, Double Pole/Double Throw (DPDT)

Relays

American-style relays, SPST, SPDT, DPST, DPDT
IEC relay symbol, SPDT

Circuit Breakers

Molded Case Circuit Breaker (MCCB)

Transformers

Transformer with center tap
Current Transformer
Zero-Sequence Current Transformer (ZSCT) (a.k.a. window-type current transformer)
Bushing-Type Current Transformer
Voltage Transformer