Electronic Components Basics

An electronic component refers to a singular device or element utilized on a printed circuit board, possessing specific electrical characteristics such as conductivity and insulation. It serves a distinct function within an electronic circuit, earning designations like electrical component or PCB component. These components can be categorized as active or passive, with each playing a unique role in managing the flow and regulation of electrical signals. The superior quality of these components directly influences the overall excellence of electronic products.

To ensure your project’s success, it is imperative to engage the services of a highly proficient component purchaser. FS Technology stands as your ideal partner, facilitating seamless procurement operations. Should you have any requirements in this domain, we encourage you to reach out to us promptly. This article, presented by FS Technology, aims to equip enthusiasts with comprehensive foundational knowledge about electronic components, thereby enriching their understanding of this field.

Table of Contents

Classification of Electronic Components

Electronic components can be classified based on various criteria, enabling a better understanding of their roles and functions within electronic circuits. The primary classifications are as follows:

  • Active Components: These components can control and amplify electrical signals but require an external power source to function effectively. Examples include transistors, operational amplifiers, and integrated circuits. Active components are essential for tasks such as signal processing, amplification, and controlling the flow of current in electronic circuits.
  • Passive Components: These components cannot control or amplify electrical signals. They operate without a need for an external power source and respond to changes in voltage and current. Examples of passive components include resistors, capacitors, inductors, and various types of switches. Passive components play crucial roles in filtering, energy storage, voltage regulation, and signal conditioning.
  • Discrete Components: Discrete components are individual electronic devices that perform specific functions and are distinct, separate entities. They are often used in simple circuits and can be easily replaced or interchanged. Examples include individual transistors, resistors, capacitors, and diodes.
  • Integrated Components: Integrated components consist of multiple discrete components combined into a single package or chip. These components are manufactured using integrated circuit technology, where several transistors, resistors, capacitors, and other components are integrated into a semiconductor substrate. Integrated circuits offer advantages such as reduced size, lower power consumption, and improved performance. They are the backbone of modern electronics, enabling complex systems, microprocessors, memory chips, and more.

Passive Electronic Components


Resistors are passive components utilized to regulate the flow of current in a circuit by impeding the passage of electrical current. They play a vital role in controlling voltage levels, limiting current, and safeguarding sensitive components. The unit of measurement for resistors is ohms, which quantifies their resistance to the flow of electrical current.


Electronic component resistor symbol

Types of Resistors

Types of PCB Resistors

The picture above showcases various types of resistors, including fixed resistors, thin-film resistors, and LDR resistors, among others.

  • Fixed Resistor: This type of resistor maintains a constant resistance during operation and is constructed using conductive materials such as carbon film, metal film, or metal oxide.
  • Thin-Film Resistors: These resistors also possess a fixed resistance value, and their distinctive feature lies in the deposition of a thin-film material on an insulating substrate. Thin-film resistors offer high precision and stability, making them suitable for precise electronic applications.
  • LDR Resistor: It is a unique type of resistor whose resistance value changes in response to varying light levels. Commonly used in photosensitive circuits, automatic lighting systems, and photosensitive electronic equipment, LDR resistors facilitate light-controlled functions in electronic devices.


Capacitors are passive components responsible for the storage and release of electrical charge. They play a crucial role in smoothing voltage fluctuations, energy storage, and signal coupling within electronic circuits. The formula for calculating the capacitance (C) of a capacitor is given by:

C = Q / V


C: represents the capacitance in farads (F).

Q: denotes the charge stored in coulombs (C).

V: signifies the voltage across the capacitor in volts (V).

The functions generated in the board include:

  • Power supply circuits: Capacitors are used in power supply circuits to smooth out voltage fluctuations and reduce ripples. They store electrical energy when the voltage is high and release it when the voltage drops, providing a more stable and continuous power output.
  • Coupling AC signals: Capacitors are employed for coupling AC signals between different stages of an electronic circuit while blocking any DC component. They are also used for decoupling purposes to remove noise and interference from power supply lines.
  • Energy Storage: Capacitors are used in various applications where short-term energy storage is required. This includes camera flashes, flashlights, and backup power supplies for electronic devices.
  • Signal Conditioning: Capacitors are used in signal conditioning circuits to block DC offset and amplify or filter specific frequency components of a signal.
  • Radio Frequency (RF) Filters: Capacitors are used in RF filters to pass or block certain frequency ranges in communication systems and RF circuits.
  • Tuning Circuits: Capacitors are used in tuning circuits to adjust the resonance frequency of radio receivers and transmitters.


electronic component capacitor symbol

Types of capacitors

Types of electronic component capacitors

Polarized Capacitors

Polarized capacitors have a specific polarity, requiring them to be connected in a particular direction within a circuit. They find prominent usage in applications involving DC (direct current) voltage. The two common types of polarized capacitors are as follows:

  • Electrolytic Capacitors: Comprising two electrodes, an anode, and a cathode, separated by a dielectric electrolyte. Typically, the anode is made of aluminum foil, while the cathode is coated with an electrolyte. These capacitors offer high capacitance values and larger sizes, making them ideal for functions such as charge storage, filtering, and coupling.
  • Tantalum Capacitors: Feature electrodes made of tantalum metal and possess a similar structure to electrolytic capacitors. However, they utilize tantalum oxide as the electrolyte. These capacitors are widely employed in high-performance electronic products, including mobile devices, computers, and communication equipment, particularly in cases demanding high-frequency performance and stability.

Non-Polarized Capacitors

Non-polarized capacitors lack a specific polarity, enabling them to be connected in any direction within a circuit. These capacitors are commonly employed in AC (alternating current) voltage applications and scenarios where the signal polarity constantly changes. The following are common types of non-polarized capacitors:

  • Ceramic Capacitors: Constructed using ceramic materials and often employing lead or silver as the electrodes. These capacitors offer advantages such as high stability, excellent frequency response, and cost-effectiveness.
  • Film Capacitors: Manufactured using thin film deposition technology, film capacitors include variants such as metal film capacitors, polyester film capacitors, and polypropylene film capacitors. They are known for their high precision, stability, and durability.
  • Supercapacitors: Also referred to as supercapacitors or electrochemical capacitors, these capacitors are a relatively new type. They boast high energy density and power density, enabling rapid charging and discharging, making them well-suited for applications requiring high-power transient output.


Inductors are passive components that store energy in magnetic fields when an electric current flows through them. They find frequent usage in applications such as filters and energy storage.

The inductance (L) of an inductor relies on several factors, encompassing the number of turns in the coil, the core material, the coil’s dimensions, and the core’s permeability. The fundamental formula for calculating the inductance of an inductor is as follows:

L = (N^2 * μ * A) / l


L: signifies the inductance in Henries (H).

N: denotes the number of turns in the coil.

μ: represents the permeability of the core material (a constant).

A: signifies the cross-sectional area of the coil’s magnetic core.

l: refers to the length of the coil.

Working Principle

The behavior of an inductor is governed by Faraday’s law of electromagnetic induction. When the current through an inductor changes, it induces a voltage across the component proportional to the rate of current change. This property causes inductors to resist sudden changes in current flow, resulting in a “back EMF” effect that opposes any change in the current.

There are various types of inductors designed for specific applications:

  • Air-Core Inductors: Have a hollow magnetic core, meaning there is no magnetic material surrounding the inductor coil. They are suitable for low-frequency applications.
  • Iron-Core Inductors: The magnetic core is made of ferrous material, such as iron powder or ferrite. They offer high inductance and energy storage capacity, making them ideal for high-frequency applications.
  • Chip Inductors: Compact inductive devices with coils made of thin magnetic material sheets, allowing for a small size and high energy storage capacity. They are commonly used in communication equipment.
  • Variable Inductance: Allow the inductance to be adjusted by manipulating design parameters like the number of windings or the position of the magnetic core. They are useful for adjusting frequency, impedance matching, and signal transmission in circuits.
  • Coupled Inductors: Feature two or more inductive components coupled together by a magnetic field. They find applications in sensors, filters, and power amplifiers.
  • High-Frequency Inductors: Specially designed for high-frequency PCB, have low DC resistance and a high self-resonant frequency, allowing for more effective transmission of high-frequency signals.
  • Power Inductors: With larger coils and magnetic cores, can withstand higher current and power levels. They are commonly used in equipment with high current and power demands, such as industrial control boards.

Inductors in circuits

  • Filters: Inductors are combined with capacitors to form passive filters capable of separating or blocking specific frequency components in a signal.
  • Power Supplies: Inductors play a vital role in DC-DC converters and switching regulators, efficiently storing and transferring energy.
  • Electromagnetic Interference (EMI) Suppression: Inductors assist in reducing unwanted electromagnetic noise within electronic circuits.
  • RF Circuits: Inductors are critical components in radio frequency circuits, used in applications such as antenna matching networks and impedance matching circuits.
  • Transformers: Inductors are integral to PCB transformers, facilitating the transfer of energy between multiple coils, often involving voltage and current level changes.


Diodes are semiconductor devices that exhibit a unidirectional flow of current, functioning as one-way valves for electrical current. They are extensively utilized in various applications, including rectification, voltage regulation, and signal demodulation.

Diodes play a fundamental role in PCBA boards, enabling precise control and manipulation of current flow, making them indispensable components for efficient and reliable electronic circuits.


electronic component Diodes symbol

Types of diodes

  • Rectifier Diode: Utilized for converting AC to DC in rectifier circuits. Examples include 1N4001, 1N5408, etc.
  • Zener Diode: Designed to operate in the reverse breakdown region to maintain a constant voltage across it. Used in voltage regulation circuits.
  • Light Emitting Diode (LED): Emits light when current flows through it in the forward direction. Employed in various lighting and display applications.
  • Schottky Diode: Exhibits a lower forward voltage drop and faster switching speed compared to regular diodes. Applied in high-frequency applications.
  • Varactor (Varicap) Diode: Designed to act as a variable capacitor when a voltage is applied in the reverse direction. Utilized in voltage-controlled oscillators and tuning circuits.
  • Photodiode: Converts light energy into electrical current. Employed in light sensors and optical communication systems.
  • PIN Diode: Possesses an intrinsic layer between the P-type and N-type regions, making it suitable for RF and microwave applications.
  • Tunnel Diode: Demonstrates a negative resistance region, used in high-frequency oscillators and amplifiers.
  • Schottky Barrier Diode (SBD): Combines a metal-semiconductor junction to achieve a low forward voltage drop and fast switching characteristics.
Type of DiodeExamples
Rectifier Diode1N4001, 1N5408
Zener Diode1N4728A (4.7V), 1N4742A (12V), BZX55C3V9 (3.9V)
Light Emitting Diode (LED)5mm Red LED (LTL-4231), 3mm Green LED (LL-503GD2E-2G-3G)
Schottky Diode1N5817 (20V, 1A), BAT54S (30V, 200mA)
Varactor (Varicap) DiodeBB112 (30V), BB639E7904 (25V)
PhotodiodeBPW34 (Silicon PIN), TEMD6010FX01 (Infrared)
PIN DiodeHSMP-382x Series (Surface Mount), MA4P7451F-1072T (RF)
Tunnel Diode1N3712 (Germanium), MV1401 (Silicon)
Schottky Barrier Diode (SBD)BAT41 (30V, 100mA), HSMS-285x Series (Surface Mount)

Active Electronic Components


Transistors are active PCB components with versatile functionality, serving as amplifiers, switches, and signal modulators. Their vital role extends to digital logic, making them indispensable in microprocessors and various electronic devices.


electronic component Transistors symbol

Types of Transistors

Types of electronic component Transistors

I. Bipolar Junction Transistor (BJT):

a. NPN (Negative-Positive-Negative): An NPN transistor comprises a thin P-type semiconductor layer sandwiched between two N-type layers. It facilitates current flow from the collector to the emitter when a small current is applied to the base terminal.

b. PNP (Positive-Negative-Positive): In a PNP transistor, a thin N-type semiconductor layer is sandwiched between two P-type layers. It enables current flow from the emitter to the collector when a small current is applied to the base terminal.

II. Field-Effect Transistor (FET):

a. Junction Field-Effect Transistor (JFET): JFETs have a channel made of either N-type or P-type semiconductor material and a gate terminal that controls the current flow through the channel.

b. Metal-Oxide-Semiconductor FET (MOSFET): MOSFETs, the most common type of FET, feature a metal gate insulated from the semiconductor channel by an oxide layer. MOSFETs are further categorized as:

i. Enhancement Mode MOSFET: Requires a positive voltage at the gate to create a conducting channel between the source and the drain.

ii. Depletion Mode MOSFET: Operates with a conducting channel by default and requires a negative voltage at the gate to turn it off.

III. Darlington Transistor: Consisting of two BJTs connected in a specific configuration to provide a high current gain, Darlington transistors are used in applications requiring significant current amplification.

IV. Insulated Gate Bipolar Transistor (IGBT): IGBTs are a hybrid of MOSFET and BJT, combining the high input impedance of a MOSFET with the high current-carrying capability of a BJT. They find common use in high-power applications like motor drives and power inverters.

V. Phototransistor: This light-sensitive transistor operates based on the amount of incident light on its base. When light falls on the base, it allows more current to flow from the collector to the emitter.

VI. Unijunction Transistor (UJT): UJTs are a type of thyristor that exhibits unique behavior, producing a relaxation oscillator waveform. They are primarily used in timing and triggering circuits.

Operational amplifier

An operational amplifier, commonly known as an op-amp, is a highly versatile and extensively employed electronic component capable of performing various mathematical operations and amplification functions. Functioning as a high-gain, direct-coupled amplifier with differential inputs and a single output, the op-amp plays a pivotal role in a diverse array of electronic applications. Its widespread usage is attributed to its exceptional performance and reliability in performing precise mathematical calculations and amplification tasks within electronic circuits.


electronic component Operational amplifier​ symbol

Application in PCB

  • Signal Amplification: Op-amps are utilized to amplify weak signals from sensors, transducers, and other sources to levels suitable for further processing or measurement.
  • Mathematical Operations: Execute mathematical operations such as addition, subtraction, integration, and differentiation. This capability proves valuable in signal processing, filtering, and control systems.
  • Voltage Follower (Buffer): Configured as voltage followers, op-amps provide unity gain (gain of 1) and are employed to isolate circuits with varying impedance levels.
  • Active Filters: Op-amps, when used in conjunction with passive components, facilitate the creation of active filters that offer improved performance and flexibility compared to passive filters alone.
  • Oscillators and Signal Generators: Instrumental in oscillator circuits, generating periodic waveforms for various applications.
  • Comparators: By employing a reference voltage, op-amps can function as voltage comparators, delivering a digital output based on the comparison of input signals.
  • Feedback Control Systems: Play a critical role in feedback control systems, providing error amplification and correction to maintain system stability and accuracy.

Integrated Circuits

Also referred to as microchips or chips, represent miniaturized electronic circuits housing multiple interconnected electronic components and transistors on a single semiconductor substrate. Their widespread adoption in electronic devices stems from their compact size, low power consumption, and exceptional reliability.

Types of IC

  • Analog Integrated Circuit: Operate with continuous signals and perform functions such as amplification, filtering, voltage regulation, and signal conditioning. Examples include operational amplifiers (op-amps), voltage regulators, and audio amplifiers.
  • Digital Integrated Circuit: Process discrete signals (0s and 1s) and are employed in digital logic circuits, microprocessors, microcontrollers, and memory devices like RAM and ROM.
  • Mixed-Signal Integrated Circuit: Combine both analog and digital circuitry, allowing the processing of both continuous and discrete signals in a single chip. Applications include analog-to-digital converters (ADC) and digital-to-analog converters (DAC).
  • Field-Programmable Gate Array (FPGA): Users can configure to implement custom digital logic circuits. They provide flexibility and reconfigurability, making them suitable for prototyping and rapid development of digital systems.
  • Memory Integrated Circuit: Store data and program code for use in various devices. Examples include RAM (Random Access Memory), ROM (Read-Only Memory), flash memory, and EEPROM (Electrically Erasable Programmable Read-Only Memory).
  • Digital Signal Processor (DSP): Optimized for digital signal processing tasks, such as audio and video processing, communications, and image manipulation.
  • Radio Frequency Integrated Circuit (RFIC): Designed for wireless communication applications and encompass components like RF amplifiers, mixers, and oscillators.


IC NO.TypeExamples
LM741AnalogOperational Amplifier
LM317AnalogAdjustable Voltage Regulator
NE5532AnalogDual Low-Noise Op-Amp
LM386AnalogAudio Power Amplifier
AD620AnalogInstrumentation Amplifier
74HC00DigitalQuad 2-input NAND Gate
555DigitalTimer IC
74LS138Digital3-to-8 Decoder
74LS164Digital8-bit Serial-in/Parallel-out Shift Register
CD4017DigitalDecade Counter/Divider
ADC0804Mixed-Signal8-bit Analog-to-Digital Converter
DAC0808Mixed-Signal8-bit Digital-to-Analog Converter
MAX232Mixed-SignalRS-232 Transceiver
MCP3008Mixed-Signal8-Channel 10-bit ADC
Xilinx Spartan-6FPGAXilinx Spartan-6
Altera Cyclone IVFPGAAltera (Intel) Cyclone IV
Lattice iCE40FPGALattice iCE40
74LS189Memory4-bit Random-Access Memory
27C256Memory32KB EPROM
25LC512Memory64KB SPI EEPROM
AT29C256Memory32KB Flash Memory
Texas Instruments TMS320C6748DSPTexas Instruments TMS320C6748
Analog Devices ADSP-21489DSPAnalog Devices ADSP-21489
NXP (Freescale) DSP56858DSPNXP (Freescale) DSP56858
MAX2606RFICFM Transmitter
AD8361RFICRF RMS Detector
HMC980LP4ERFICRF Power Amplifier

Electronic Component FAQ

Indeed, while FS Technology isn’t an electronic component store per se, we do provide component procurement services for business endeavors. Leveraging our experience in PCB assembly services, we’ve forged alliances with major brands to secure high-quality component supplies at reduced costs.

If you’re looking to procure components on your own, FS Technology recommends our partners: Digi-Key, Mouser, RS Components, Element14, and Future Electronics. These are reputable electronic component stores you can trust.

Component values and parameters refer to resistor values, capacitor values, etc., which are very important for circuit trace width design, and you can find them on the component itself or on the package.

Choose based on project design requirements and ease of assembly. Once your design is complete, please send the design files to the PCBA company. They will review the files and confirm whether they have the capability to provide PCB assembly services for you.

The operating temperature range is typically specified in its datasheet. Make sure to use the component within the specified range to avoid overloading the component, which could lead to short circuits or even circuit board damage.

This refers to the phenomenon where static electricity is discharged onto electronic components. Even the slightest static discharge can cause damage to electronic components. To prevent this, manufacturing facilities often implement a series of anti-static measures.

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