Electronic Component Circuit Symbols

- overview of the electronic circuit symbols, standards used in circuit diagrams and further pages with sections of circuit symbols.

Electronic component circuit symbols includes:

    •  Circuit symbols overview
    •  Passive component symbols
    •  Semiconductor diode symbols
    •  Transistor / FET symbols
    •  Wires, switches, connectors
    •  Logic symbols
    •  Analogue circuit blocks

Circuit symbols are used for electronic circuit diagrams. The various symbols are used to represent different electronic components and devices in circuit diagrams from wires to batteries and passive components to semiconductors, logic circuits and highly complicated integrated circuits.

By using a common set of circuit symbols in circuit diagrams, it is possible for electronic engineers around the globe to communicate circuit information concisely and without ambiguity.

Although there are a number of different standards in use for the different circuit symbols around the globe, the differences are normally small, and because most systems are well known there is normally little room for ambiguity.

Circuit symbol systems

There is a number of different systems used for circuit symbols around the globe. The main ones are listed below:

• IEC 60617:   This standard is issued by the International Electrotechnical Commission, and this standard for electronic component symbols is based on the older British Standard, BS 3939 which in turn was developed from the much older British Standard 530. Often reference is made to BS electric component standard, and the IEC standard is now the one that is used. The database includes around 1750 circuit symbols overall.
• ANSI standard Y32:   This standard for electronic component symbols is the American one and is also known as IEEE Std 315. This IEEE standard for circuit symbols has various release dates.
• Australian Standard AS 1102:   This is an Australian standard for electronic component symbols.

Of these the IEC and ANSI/IEEE standards for electronic symbols are those that are most widely used. Both are quite similar to each other although there are a number of differences. However as many circuit diagrams are used globally, both systems will be well known to most electronics engineers.

Circuit notation and reference designators

When developing a circuit diagram, it is necessary to identify the individual components. This is particularly important when using a parts list as the components on the circuit diagram can be cross related to the parts list or Bill of Materials. It is also essential to identify components as they are often marked on the printed circuit board and in this way the circuit and the physical component can be identified for activities such as repair, etc..

In order to identify components, what is termed a circuit reference designator is used. This circuit reference designator normally consists of one or two letters followed by a number. The letters indicate the type of component, and the number, defines which particular component of that type it is. An example may be R13, or C45, etc..

In order to standardise the way in which components are identified, the IEEE introduced a standard IEEE 200-1975 as the "Standard Reference Designations for Electrical and Electronics Parts and Equipments." This was later withdrawn and later the ASME (American Society of Mechanical Engineers), initiated the new standard ASME Y14.44-2008.

Some of the more commonly used circuit reference designators are given below:

Circuit diagram symbols

There are very many circuit diagram symbols for different components. Accordingly the different symbols have been grouped into different sections which have been provided on the pages as set out below:

• Passive component circuit symbols:   This section includes many of the common passive component circuit symbols including resistors, capacitors and inductors, including transformers. Read more . . .
• Semiconductor diode symbols:   This section includes circuit symbols for the variety of forms of semiconductor diodes that are available. Read more . . .
• Transistor & FET circuit symbols:   This page includes circuit symbols for transistor and FET components as well as thyristor, DIAC and TRIAC. Read more . . .
• Wires, switches, connectors:   The circuit symbols for wires connectors, and switches. Read more . . .
• Logic circuit symbols:   Logic circuit blocks are widely used in digital electronics. These logic elements may be contained within an IC, but need to be depicted as separate elements to show the functionality of the circuit. Read more . . .
• Analogue functional building blocks:   Often circuit symbols are required for building blocks that are more than simple components. These blocks may be bought in as specific items, or they may be sued to give a block diagram of a system. Read more . . .

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