Electronic symbol for the resistor

A basic electronic symbol

When designers don’t understand what components are being used and how they are interconnected, the PCBA development process can come crashing down around them. Therefore, a solid understanding of basic electronic symbols and their functions is essential for designers and engineers whose work dictates the success of the rest of the PCBA development process. In the table below are some of the basic types of electronic symbols that should be well-known and understood:

Table of basic electronic symbols

Common electronic symbols

Commonly Used Basic Electronic Symbols and Their Functions

When you hear the language used to describe the building of electronic circuits, boards, and systems, the reference is invariably to a software language—Basic, FORTRAN, C/C++/C#, Java, Ruby, HTML, XML, etc. Yet, there is also an electronics hardware language, which is utilized by professionals in all industries where electronic systems are a part of the system design. This language is electronic symbols.

Knowing electronic symbols and their functions within circuits and systems is important in understanding their operation and expected performance. In fact, the crucial stages of design and testing are only possible with this important knowledge. Let’s look deeper into the different symbol types and their functions:

Basic Electronic Symbols and Their Functions


Wires are the most basic electronic symbol representing a physical, electrical connection between two or more points.

  • Minimally, a wire should have a source and termination connection point.

  • A wire must be continuous and unbroken for current to flow between connected electrical points.

Power Supplies

Onboard power supplies are components represented by one of the symbols shown in the chart, such as a battery.

  • Ground indications are included in these symbols to ensure the circuit completes a path from the source and back to the source.


As a common active component, transistors are used for switching and amplification.

  • Although many types of transistors exist, BJT, JFET, and MOSFETs are the most common.


Testing and verifying that an electronic circuit performs as intended is essential.

  • Meters indicate what types of testing equipment to employ and where to connect them.

  • Ammeters and voltmeters are the most common meters found on circuit diagrams.


Single junction devices, employing P and N materials, are used primarily for switching and isolation.

  • There are several types of diodes used in different applications.

  • Diode types include  Zener, Schottky, and LEDs.


As one of the most common components found on a PCB, capacitors are basic energy storage devices.

  • These parts block DC and pass AC, which makes them excellent signal couplers for RF applications.


The resistor is the most basic passive component in circuit design. Exemplifying Ohm’s Law, the device’s resistance is equal to the voltage across it divided by the current flowing through it. 

  • Resistors are one of the most commonly used parts in PCB layout.


Switches are essential for electronic circuit operation, as they control when a system or subsystem is active or inactive.

  • Switches connect sources with outputs of circuits in multiple combinations.

  • A DPST refers to a switch with double poles (circuits) and a single throw. The two circuits are operated in tandem within the switch.

Output Devices

There are many output devices that may be used on circuit boards, and their functions vary according to need.

  • Common types include buzzers, antennas, speakers, lamps, and motors.

Input Devices

Electronic signals exterior to the circuit board are typically referred to as an input device.

  • These signals can be analog or digital, depending on the application.

  • One standard input device is a microphone.

Miscellaneous Devices

This category includes many common components and devices, such as transformers, op amps, and integrated circuits.

  • Using these parts requires careful organization or a managed component library due to their similarity of PCB footprints.

Logic Gates

Logic gates are fundamental components of digital electronic circuit design.

  • Examples include  AND, NAND, and XOR gates.

  • These devices can also be embedded in other components, such as processors and FPGA ICs.

How to Best Source Basic Electronic Symbols

Having a clear understanding of basic electronic symbols and their functions will aid you in designing and developing electronic boards and systems. With this knowledge, you can better source components and devices for your projects. However, if efficiency and accuracy are on your list of requirements, then opt for the largest online parts library that provides free footprints and symbols for your design, such as the TIP3055 and TIP2955 BJT equivalents shown below.

Commonly used BJT transistor pair

The TIP3055 and TIP2955 NPN and PNP BJT Equivalents

If you’re looking for data and information on basic electronic symbols and their functions, Ultra Librarian helps by compiling all your sourcing and CAD information in one place.

Working with Ultra Librarian sets up your team for success to ensure streamlined and error-free design, production, and sourcing. Register today for free.


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