The 10 Most Commonly Used Electronic Components and Their Functions

Introduction

Imagine the complex smart device in your hand; its core operation relies on thousands of tiny "building blocks." These "building blocks" are electronic components, the language and foundation of the modern electronic world. From the simplest LED indicator light to the microprocessors that drive artificial intelligence, all electronic devices function because these components are connected by wires or traces on a Printed Circuit Board (PCB) to form a closed circuit with a specific purpose. Whether you are a beginner in electronics or an enthusiast seeking to understand hardware design, mastering the working principles and application scenarios of these 10 most common electronic components is the key to unlocking the electronic world.

Printed circuit board (PCB) assemblies turn copper traces into working electronics by soldering a small set of fundamental parts—resistors, capacitors, diodes, transistors, integrated circuits, connectors, inductors, switches, relays, and sensors—onto the board and linking them with pads, traces, and vias for reliable electrical and mechanical connections. This introduction walks you through the 10 most commonly used electronic components you’ll see on PCBs, what each does, how they appear on schematics/silkscreen, and where they’re used in real products, so you can read a BOM with confidence and make smarter design and assembly choices.

> Recommend reading: Wearable Electronic Components: From Trackers to Wrist-Worn Micro-Computers

I. Fundamental Classification of Electronic Components: Active vs. Passive

Electronic components can be divided into two main categories based on their function in a circuit and whether they require an external energy source to operate: Active Components and Passive Components.

1.1. Passive Components

Passive components are energy acceptors. They cannot amplify signals or inject energy into the circuit. Their primary role is to consume, store, or dissipate energy.

• Characteristics: Do not provide power gain and cannot control the flow of current.
• Examples: Resistors, capacitors, inductors, etc..

1.2. Active Components

Active components are energy donors. They must rely on an external power source to operate and are capable of amplifying signals, controlling the direction of current flow, or injecting energy into the circuit.

• Characteristics: Can provide power gain and can control the flow of current.
• Examples: Diodes, transistors, integrated circuits (ICs), etc..

Almost all electronic circuits must contain at least one active component to perform a specific function.

 

II. Detailed Analysis and Applications of the 10 Most Common Electronic Components

Here are 10 of the most common and fundamental electronic components that make up modern electronic circuits, along with their practical application scenarios:

2.1. The Passive Triad: Circuit Foundations

1. Resistors

> The Resistor in Modern Electronics: Fundamentals, Advanced Applications, and Reliability

Type: Passive The resistor is one of the most common components in a circuit. Its basic function is to limit the flow of current by providing electrical resistance, dissipating electrical energy as heat when current passes through it.

• Application Scenarios:

1. - Current Limiting Protection: Used in series with Light-Emitting Diodes (LEDs) to prevent excessive current from burning out the LED.
2. - Voltage Division: Used in voltage divider circuits to provide precise reference voltages for Integrated Circuits (ICs).
3. - Current Sensing: Precision resistors are used in Battery Management Systems (BMS) to measure current consumption and charge status.
4. - Digital Logic: Used as pull-up or pull-down resistors to ensure digital signal pins maintain a stable state when no input is applied.

> Recommend reading: 10 kΩ Resistor: Principles, Advantages, and Applications in Electronic Design

2. Capacitors

> Recommend reading: PCB Capacitors: Why Is It Important and How to Choose?

> Recommend reading: Capacitor Symbols: A Guide to Understanding the Different Types

Type: Passive The capacitor is a component capable of storing electrical charge by storing energy in an electric field. Capacitors are crucial because they oppose sudden changes in voltage.

• Application Scenarios:

1. - Decoupling/Bypass: Placed near the power pins of microprocessors (CPUs/MCUs) to quickly supply instantaneous current and suppress power supply noise generated by high-speed switching, ensuring chip stability.
2. - Filtering: Used in power circuits to smooth out alternating current (AC) ripple, making the pulsating direct current (DC) more stable.
3. - Timing Circuits: Combined with resistors to form RC circuits, used for setting delays or generating oscillation frequencies.

3. Inductor

> Recommend reading: Inductor and transformer testing methods and experience

Type: Passive The inductor is a component that works by storing energy in a magnetic field when current flows through its coil. Its main characteristic is its ability to resist changes in current.

Inductance is a property of a closed circuit and a physical quantity. When the coil passes current, a magnetic field induction is formed in the coil, and the induced magnetic field will generate an induced current to resist the current passing through the coil; an inductor is an inductive component made of inductive properties. When the inductor is in the state of no current passing, it will try to prevent the current from flowing through it when the circuit is on; if the inductor is in the state of passing current, it will try to maintain the current when the circuit is off. Inductors are also called chokes, reactors, and dynamic reactors.

• Application Scenarios:

1. - Switch-Mode Power Supplies (SMPS): Core component in Boost and Buck converters, used to smooth voltage conversion and improve power efficiency.
2. - Noise Suppression: Used as chokes to filter high-frequency noise, often on power lines for USB or audio interfaces.
3. - Radio Frequency (RF) Circuits: Used for tuning and impedance matching to optimize the transmission of wireless communication signals.

2.2. Semiconductors: Controllers of Current

4. Diode

> Recommend reading: Introduction to Printed Circuit Board Diode (PCB Diode)

> Recommend reading: Diode Testing: A Comprehensive Guide for Beginners

Type: Active The diode is a semiconductor device whose core characteristic is allowing current to flow in only one direction.

• Application Scenarios:

  • Rectification: Used in power adapters to convert the AC from a wall outlet into pulsating DC.

  • Reverse Protection: Prevents damage to sensitive circuits if a user accidentally connects the battery with reversed polarity.

  • Freewheeling: Used in circuits with relays or inductive coils to absorb the reverse high voltage (flyback voltage) generated when the coil is de-energized, protecting control components like transistors.

5. Light-Emitting Diode (LED)

Type: Active An LED is a special type of diode that emits light when current flows through its p-n junction. They are highly efficient light-emitting components.

• Application Scenarios:

  • Status Indication: Used as power indicators, network status lights, or device fault alerts.

  • Illumination: Widely used in energy-efficient lighting (LED bulbs), TV backlights, and automotive headlights.

  • Optical Communication: Used in fiber optics or infrared remote controls to emit light signals.

6. Transistor

> Recommend reading: BC547 Transistor: Ultimate Guide for Engineers and Hobbyists

Type: Active The transistor is the cornerstone of modern electronic technology. It is a semiconductor device primarily used for amplifying and switching electronic signals. Common types include the Bipolar Junction Transistor (BJT) and the Field-Effect Transistor (FET).

• Application Scenarios:

1. - Switching Devices: Acts as a high-speed switch in all digital logic circuits, forming the basic building block of microcontrollers and computer chips (MOSFETs are the most widely manufactured electronic component globally).
2. - Amplifiers: Used in audio equipment and radio receivers to amplify weak analog signals.
3. - Power Control: High-power transistors (like IGBTs) are used in Electric Vehicle (EV) inverters and industrial motor drives to efficiently control large currents.

7. Integrated Circuit (IC) / Microchip

Type: Active An Integrated Circuit is a compact assembly where multiple electronic components (such as transistors, resistors, and capacitors) and their interconnecting traces are fabricated onto a single, thin, flat piece of semiconductor material (usually silicon). ICs have revolutionized electronics by enabling miniaturization, improved performance, and reduced cost.

> Recommend reading: The Future of Integrated Circuit Memory in Automotive Electronics

• Application Scenarios:

1. - Microcontrollers (MCUs): Embedded in washing machines, remote controls, and Internet of Things (IoT) devices to execute pre-set control programs.
2. - Operational Amplifiers (Op-Amps): Used for precise amplification and processing of analog signals, central to medical equipment and sensor interfaces.
3. - Timer ICs (e.g., the 555): Used to generate precise pulses, delays, or frequencies, such as in simple alarms or flashing lights.
4. - Processors (CPU/GPU): The core of computers and smartphones, responsible for all data processing and computation functions.

2.3. Electromechanical and Support Components

8. Switches and Relays

A switch is an electromechanical component that controls the flow of current by making or breaking a circuit through physical contact. A relay is a special switch operated by an electrical signal.

> Recommend reading: SPDT Switch: A Comprehensive Guide Is Here

• Application Scenarios:
  1. - User Interface: Buttons and toggle switches are used to control device power and select modes.
  2. - High-Voltage Isolation: Relays are used in automotive, home appliance, or industrial control systems to control high current or high voltage loads with a low-voltage signal, providing isolation and protection.
  3. - Safety: Used in emergency stop buttons or remote-controlled switches to provide power cut-off protection.

 

9. Connectors and Headers

Connectors and headers provide mechanical and electrical interfaces between internal system components or between a system and external devices.

• Application Scenarios:

1. - Modular Design: Used to connect two PCBs, facilitating module replacement and maintenance.
2. - External Interfaces: USB ports, power sockets, and audio jacks for connecting external power, data, or peripherals.
3. - Debugging/Programming: Pin headers are used to connect programmers or debugging tools for flashing and testing microcontrollers.

 

10. Oscillators and Crystals

These components are crucial in digital systems as they are used to generate precise and stable clock frequencies.

> Recommend reading: Oscillators: What Are They? (Definition, Types, & Applications)

• Application Scenarios:
  1. - Clock Reference: Provides the precise timing signal (the "heartbeat") for microprocessors and microcontrollers (MCUs), ensuring all operations are synchronized.
  2. - Communication Systems: Used in radio, Wi-Fi, Bluetooth, and 5G communication equipment to generate and lock onto specific Radio Frequency (RF) frequencies, ensuring accurate data transmission.

III. Conclusion: Moving Towards Practice and Creation

By understanding these 10 core electronic components, you have grasped the fundamental "vocabulary" and "grammar" required to build any electronic device. From the current-limiting resistor to the logic-executing integrated circuit, each component plays an indispensable role in the circuit.

To translate theoretical knowledge into practical skills, here are simple circuit examples using these basic components. We encourage you to try them out:

Circuit Name	Core Components	Principle
DC Lighting Circuit	Power Supply, Resistor, LED	Demonstrates the simplest closed-loop circuit, where the resistor limits current to protect the sensitive LED from burnout.
Touch Sensor Circuit	Transistor, Resistor, LED	Demonstrates how a transistor acts as a switch. A tiny current (e.g., from finger touch) is used as the base current to turn the transistor on, controlling a larger current flow to the LED.
Simple USB Flashlight	LED, Connector, Switch	A beginner-level DIY project that helps familiarize the user with component soldering and basic circuit assembly.

IV. From Design to Reality: NextPCB Helps You Manufacture Your Innovation

Understanding these core components is only the first step; translating a circuit diagram into a fully functional physical product, requires professional manufacturing and supply chain support.

As a provider specializing in PCB manufacturing and one-stop electronic assembly services, we are committed to turning your innovative designs into high-quality physical products.

NextPCB Services for Your Project:

• High-Quality PCB Manufacturing: Providing high-reliability circuit boards from prototyping to mass production.
• One-Stop Component Procurement (BOM Service): Easily solve all procurement challenges for both active and passive components, ensuring component authenticity and reliability.
• Professional PCBA Assembly: Utilizing advanced Surface Mount Technology (SMT) and Through-Hole Technology (PTH), for precise and efficient assembly of these components onto your circuit board.

Start your next project today. Let us help you efficiently manage your Bill of Materials, ensure a stable and reliable component supply, and provide exceptional manufacturing processes to transform these electronic cornerstones into your successful product.