What Are Electrical Components?

Views 1 Like Comments Comment
Like if this guide is helpful
What Are Electrical Components?

Electronic components like resistors, capacitors, amplifiers, diodes, and transistors are the backbone of the telecommunication and electronics industries, working under the covers to keep the wired world pulsing. As part of electronic circuitries, electronic components find varied uses in almost every industry: for example, in switches, radios, and televisions at home; in medical equipment for the early detection and treatment of health issues; in digital cameras, personal computers, music players, mobile phones as consumer electronics; or in the entertainment and global positioning systems (GPS) in cars. Modern technology has enhanced the performance and functionality of electronic components, resulting in their increasing use in the aerospace and defence industries. Hobbyists look for electronic components to recycle, save money, and work on their circuit projects, while other consumers just want replacement parts to repair their devices. Electronic components are easy to find in electronics shops as well as at online stores like eBay, which offers lower prices and greater variety, including hard-to-find items like vacuum tubes.

This guide offers light reading on electronic components, with advice for a satisfactory buying experience on eBay. Consumers with a basic appreciation for the composition and functions of electronic components are be self-assured shoppers, whether faced with a single item at a local shop or the thousands of choices that online stores proffer.

Classification of Electronic Components

Electronic components are basic detached devices or elements in an electronic system used to manage the flow of electricity, and they come in varying shapes, sizes, and complexities. All electronic components have two or more electrical terminals or leads, which are usually soldered to a printed circuit board, creating a discrete electronic circuit. These circuits have specific functions like oscillators, amplifiers, and radio receivers.

Electronic components are classified according to type, functions, and physical formats. The most common classification according to energy supply puts components into two broad categories: passive and active. Passive and active components are further subdivided according to their specific function. However, others include a third type of component called electromechanical components.

Passive Components

Passive components are modules that work independent of any applied voltage, except for the available alternating current (AC) circuit that they are connected to. Passive modules are not sources of energy and cannot amplify the power of signals, though they may increase current in transformers or resonant circuits. The most common types of passive electronic components are resistors, capacitors, inductors, transformers, and transducers.


Resistors are two-terminal electrical components that limit current through electrical friction in a circuit. They are the most common type of electronic components, made from elements that are poor conductors for greater resistance with general uses in power resistors which safely diffuse heat generated by devices or to control volume in electronic devices like the TV. Resistors are measured according to the degree of resistance they offer, measured in units called Ohms, as well as how much power they can handle, measured in Watts.


Capacitors are passive two-terminal electrical components; their name derives from their capacity to store energy temporarily in an electric field. The most common types of capacitors are electrolytic capacitors used in the camera flash and the cheaper ceramic capacitors, which do not need as much intense energy. Depending on how they are wired into a circuit, capacitors can be fixed, variable, or integrated, with uses like filtering and power regulation. Specialised capacitors are used for safety applications.


Inductors are the simplest of electronic components and are just coiled wires that store and release energy in the form of a magnetic field; the greater the wire coil, the larger the magnetic field generated. Inductors are used extensively in analogue circuits and signal processing as electromechanical switches, traffic light sensors, or in electrical transmission systems where they work as reactors, limiting electric current by design.


Transformers are magnetic devices that transfer electrical energy from one circuit to another through conductors. A transformer is used to raise or lower voltage in an alternate current (AC) electrical circuit and can also convert AC power to DC power.


Transducers are devices that convert one type of energy into another, using electrical signals to generate physical outcomes or physical pressure to generate electrical signals. They are mostly used in measuring instruments, magnetic cartridges, motion sensors, ultrasound imaging, electrical generators, loudspeakers and microphones.

Active Components

Active components are devices with the ability to amplify a signal or produce a power gain that is; the output signal is more powerful than the input signal. Active components are powered by a source of electricity separate from the electric signal and are thus able to work as alternating current circuits (AC), to increase power, voltage, or current. The majority of active components are semiconductors like diodes, transistors, and integrated circuits, while valves use vacuum and are considered the prototype to modern transistors.


Diodes are components with two elements that allow the flow of electric current in one direction while blocking it in the other. They are used in power regulation or communications circuits. Diodes are manufactured with both semiconductors and vacuum tubes although the popularity of vacuum tube diodes has waned in public use because of their bulky size. Semiconductor diodes are still very popular because they are lightweight and, because of mass production, cheap.


Transistors are three-terminal semiconductors that amplify electrical signals, with two of the elements acting as conductors and the third as the gate. They can also turn electricity on and off and are commonly used in transistor radios, amplifiers, hearing aids, pacemakers, and switches.


Valves, also known as vacuum tubes, are active components that control the flow of electric current through a vacuum in a sealed container. They are generally used for electrical signal amplification, rectification, creation, or switching, and are used in microwave ovens, x-ray technology, and as cathode ray tubes (CRT) for vibrant display in televisions. Valves are very popular as audio amplifiers for guitar musicians who want an extra depth to their sound production.

Integrated Circuits (ICs)

Integrated circuits are specially made semiconductors that contain complete electronic circuits with transistors, resistors, diodes, capacitors, and other parts. They are also known as silicon microchips, some with billions of transistors embedded on a single chip. Integrated circuits are analogue, digital, or a combination of both, and form the basis of the modern computer processor.

Light Emitting Diodes (LEDs)

Light-emitting diodes (LEDs) are semiconductors that emit light with electrical energy and are considered a source of smart lighting because of their efficient use of energy. They are found in virtually every industry and most devices as indicator lamps in clocks, watches, optical mice, and remote controls, lasting longer than traditional light sources because they do not use a filament.

Electromechanical Components

Some camps include a third classification for electronic components as the electromechanical type. Electromechanical components are those that exhibit useful properties when a manual or electrical force is applied to them. They include terminals, cables, switches, and sockets, as well as fuses, circuit breakers and lamps. Many of the components here are considered passive electronic components since they work independent of any applied charge.

The table below shows the three main types of electronic components, their features and examples.

Classification of Electronic Components




Distinctive Features

work independent of applied charge, do not produce energy, cannot amplify energy

can amplify signal or produce power gain, powered by a source, work as Alternating Current (AC)

have useful properties when manual or electric force is applied, work independent of applied charge


resistors, capacitors, transformers, inductors, transducers

diodes, transistors, valves, integrated circuits, LEDs

cables, switches, circuit breakers, fuses, terminals

How to Buy Electronic Components on eBay

You can easily find electronic components with the specific characteristics you need on eBay, whether it is transformers, capacitors, resistors, or inductors, in all sizes, material, and price tags. Whatever your budget, you have the option of using the price filter to limit search results to what is affordable to you. Some sellers offer free shipping, bundle prices, or price the items together with postage fees, so be sure to look for those if their items are good quality and as described and you're looking to save a few pounds.

If you are replacing electronic components, look for those with specifications that match your old one, as any differences can cause devices to malfunction. When considering used items, remember that signs of wear like discoloration, burns, or cracks could indicate a bigger problem that is not worth your time and money. Check that the item description matches the photos posted by the seller and ask for clarification or close-ups; many sellers happily oblige with quick answers and more photos. It is also a good idea to ask the seller about the type of packaging they use for shipping, as electronic components are fragile. Be a model buyer and leave constructive feedback on the seller, the item and your entire buying experience on eBay.


Technological advances and innovations and the growth in internet communication have spurred the global demand for electronic components into a burgeoning billion pound market. As the heart of electronics, these components are found in most everyday devices like computers, speakers, phones, and television as well as in medical and x-ray equipment, but are so useful that they have been credited with the success of space exploration and the development of defence electronics. Even though electronic components come in different sizes, shapes, and physical formats, they all work to manage the flow of electric current and are divided into passive and active components. Examples of electronic components include transducers, resistors, inductors, capacitors, and integrated circuits.

Wherever one decides to source for their electronic components, be it eBay or brick and mortar stores, they should ensure that the sensitive items are handled and packaged with care, as they are susceptible to damage from static electric charge.


Have something to share, create your own guide... Write a guide
Explore more guides