What are the electronic components?
I. Introduction
Electronic components are the basic components of electronic circuits and electronic systems. They are like the “cells” of the electronic world, building a huge system of modern electronic technology. From daily smartphones and computers to automation equipment in industrial production and precision instruments in the aerospace field, they are inseparable from the support of electronic components. Understanding the types, characteristics and applications of electronic components is crucial for electronic engineers, electronics enthusiasts and practitioners in related industries. This article will introduce the classification of electronic components in detail, including passive components, active components, connection and packaging components, electromagnetic components, power management components, display and sensor components, etc., and conduct an in-depth analysis of the common specific components in various types of components.
II. Passive components
(I) Resistors
Resistors are one of the most basic components in electronic circuits, and their code name is “R”. It controls the current in the circuit by hindering the flow of current and has many important functions. In the circuit, resistors can be used for current shunting, current limiting, voltage division, biasing, etc. For example, in a current limiting circuit, a resistor can limit the current passing through a component to prevent the component from being damaged by excessive current; in a voltage divider circuit, it can divide the voltage into different parts to provide appropriate voltages for different components in the circuit.
There are many types of resistors. According to the installation method, they can be divided into direct-insertion resistors and chip resistors; according to the material process, there are solid resistors, wirewound resistors, film resistors, sensitive resistors, etc. Different types of resistors have different characteristics and applicable scenarios. For example, chip resistors are small in size and suitable for use in small electronic devices; while wirewound resistors have higher precision and stability and are often used in circuits with strict requirements on resistance values.
(II) Capacitors
Capacitors are components that can store charge and energy, and are generally represented by “C” plus numbers in circuits. It consists of two metal films close to the lead pins, separated by an insulating dielectric material in the middle. Capacitors have the characteristics of blocking direct current and passing alternating current, which makes them widely used in electronic circuits.
In terms of power supply smoothing, capacitors can filter out the AC component in the power supply and make the output DC voltage more stable; in the filter circuit, it can selectively pass or block signals of specific frequencies, thereby eliminating noise signals in the circuit; in the coupling circuit, capacitors can transfer signals from one circuit to another while blocking the DC component.
There are many types of capacitors, the most common of which are aluminum electrolytic capacitors, ceramic capacitors, and film capacitors. Aluminum electrolytic capacitors have a large capacitance and are often used in power supply filtering and other occasions that require large-capacity capacitors; ceramic capacitors have the advantages of good high-frequency characteristics and high stability, and are widely used in high-frequency circuits.
(III) Inductors
Inductors are made by winding an insulated wire around an insulating frame for a certain number of turns, and some are also added with magnetic cores or iron core materials. When powered on, they generate inductance. They are components that can convert electrical energy into magnetic energy and store it. They are also called chokes, reactors, and dynamic reactors. In circuits, “L” plus a number is often used to represent it, such as “L6” for an inductor numbered 6.
The characteristic of an inductor is that it can pass direct current and resist alternating current. Direct current can pass through the coil, and the direct current resistance is the resistance of the wire itself, with a very small voltage drop; when an alternating current signal passes through the coil, a self-induced electromotive force will be generated at both ends of the coil, and the direction of the self-induced electromotive force is opposite to the direction of the external voltage, which hinders the passage of alternating current. The higher the frequency of the alternating current, the greater the impedance of the coil.
Inductors are often used in circuits for filtering, boosting, resonance, and frequency division. In a filter circuit, it can form a filter network with a capacitor to filter out interference signals of a specific frequency; in a boost circuit, the energy storage characteristics of the inductor can be used to increase the voltage; in a resonant circuit, the inductor and the capacitor can cooperate to generate an oscillation signal of a specific frequency.
III. Active components
(I) Diode
A diode is a basic electronic component, composed of a P-type semiconductor and an N-type semiconductor, with two terminals, namely an anode and a cathode. It has unidirectional conductivity, which is one of its most important characteristics.
In a rectifier circuit, a diode can convert an alternating current signal into a direct current signal and is widely used in power supply circuits. For example, the common bridge rectifier circuit is composed of four diodes, which can convert AC into pulsating DC, and then obtain smooth DC after passing through the filter circuit.
In the voltage stabilization circuit, the voltage stabilizing diode uses the reverse breakdown state of the PN junction, and its current can vary in a wide range while the voltage remains basically unchanged, which plays a role in voltage stabilization. When the input voltage fluctuates, the voltage stabilizing diode can maintain the stability of the output voltage and provide a stable operating voltage for other components in the circuit.
In addition, diodes can also be used for signal detection, light emission (light-emitting diodes), photoelectric conversion (photodiodes) and other functions.
(II) Transistor
A transistor is a semiconductor device composed of three or more layers of different types of semiconductor materials, and is an indispensable component in modern electronic devices. It has the function of amplifying and controlling current, and its main functions include signal amplification, switch control, voltage stabilization, etc.
In the amplifier circuit, the transistor can amplify the weak input signal into an electrical signal with a larger amplitude value. For example, in an audio amplifier, the transistor can amplify the audio signal and drive the speaker to produce a loud sound.
In the switch control circuit, the transistor can be used as a contactless switch, which controls the conduction and cutoff between the collector and the emitter by controlling the base current, thereby realizing the switch control of the circuit.
Transistors are divided into bipolar transistors (BJT) and metal oxide semiconductor field effect transistors (MOSFET). Bipolar transistors have high current amplification capabilities and are suitable for some occasions with high current amplification requirements; while MOSFET has the advantages of high input impedance, low noise, and low power consumption, and has been widely used in integrated circuits and high-speed circuits.
(III) Integrated Circuits
Integrated circuits are components that integrate multiple electronic components (such as transistors, capacitors, resistors, etc.) on a small silicon chip to form complex circuits. According to the degree of integration, integrated circuits can be divided into large-scale integrated circuits (LSI), very large-scale integrated circuits (VLSI) and ultra-large-scale integrated circuits (ULSI).
Integrated circuits have the advantages of high integration, small size, low power consumption, and stable performance. It is widely used in computers, communications, consumer electronics, automotive electronics and other fields. For example, in a computer, the central processing unit (CPU) is a highly integrated integrated circuit that can perform various complex computing and control tasks; in a smartphone, it contains a variety of integrated circuits, such as baseband chips, application processor chips, etc., which realize multiple functions such as communication, computing, and entertainment.
IV. Connection and packaging components
(I) Connectors
Connectors are components used for electrical connections between or within electronic devices, which are easy to assemble and maintain. It can achieve reliable connections between different circuits and ensure the transmission of signals and electrical energy.
There are many types of connectors, and the common ones are SMT connectors, samtec connectors, and Molex connectors. Different types of connectors have different structures and characteristics and are suitable for different application scenarios. For example, SMT connectors are suitable for surface mounting technology and have the advantages of small size and high mounting accuracy; while Molex connectors have the characteristics of reliable connection and high plug-in and pull-out times, and are often used in industrial equipment and automotive electronics.
(II) Switches
Switches are components that control the on and off of circuits, and are divided into mechanical switches and electronic switches. Mechanical switches connect and disconnect circuits through mechanical actions, such as common push button switches and toggle switches; electronic switches use the characteristics of electronic components to control the on and off of circuits, such as transistor switches and relay switches.
Switches are widely used in electronic circuits. For example, in power circuits, switches can control the on and off of power; in signal control circuits, switches can select different signal paths.
(III) Packaging technology
Packaging technology is the physical shell of electronic components, which protects the internal circuits and provides mechanical support. Different packaging types are suitable for different application scenarios.
Common packaging types include plug-in packaging and surface mount packaging (SMD). Plug-in packaging is inserted into the socket or soldered to the circuit board through pins, such as DIP packaging and TO packaging; surface mount packaging is to solder components directly to the surface of the circuit board, such as QFN packaging and LGA packaging. Surface mount packaging has the advantages of small size and high mounting efficiency, and is suitable for miniaturized and high-density electronic devices.
V. Electromagnetic Components
(I) Transformer
A transformer is a device that uses the principle of electromagnetic induction to change the AC voltage. It is made of a primary coil and one or more secondary coils wound on an insulating frame and a silicon steel core. Its working principle is that the primary coil inputs AC power, and the changing current passing through the coil generates a changing magnetic field. The changing magnetic field passes through the secondary coil, thereby generating a changing current output in the secondary coil.
The transformer converts alternating current (AC power). According to the turn ratio of the primary coil and the secondary coil, it can achieve the function of stepping up or down. When the number of turns of the primary coil is less than the number of turns of the secondary coil, it is a step-up transformer; otherwise, it is a step-down transformer.
Transformers are widely used in power systems, electronic equipment, communication systems and other fields. In power systems, transformers are used to increase or decrease voltage to achieve long-distance transmission and distribution of electrical energy; in electronic equipment, transformers can provide suitable voltages for different circuits.
(II) Relay
A relay is an electrical control device that uses electromagnetic effects to achieve circuit on-off control. It consists of an electromagnetic system, a contact system and a reset mechanism. When the electromagnetic system is powered on, electromagnetic attraction is generated, causing the contacts to close or open, thereby controlling the on and off of the circuit.
The relay has the function of isolating the control circuit and the load circuit, which can improve the safety and reliability of the circuit. It is often used in fields such as automation control and power protection. For example, in industrial automation production lines, relays can control the start and stop of various devices according to control signals.