Circuit diagrams, if widely discussed, may not be a problem that an Oxford dictionary can solve. Just the basic circuit diagram and symbols are enough to talk about One Thousand and One Nights. I will only use limited space here to list common basic circuit diagram symbols and briefly introduce their symbols or functions.
The standard of circuit diagram symbols is not fixed, and there are slight differences depending on the region. This article complies with the current international standard IEC 60617.
Usually in a circuit, the source of energy - the power supply is the biggest thing. So let's start with the power supply.
Circuit diagram symbols of power supply
There are two common types of power supply, one is single power supply and the other is multiple power supply. As shown below.
High-quality power supplies generally have multinational certification marks such as FCC, American UL, and China Great Wall. These certifications are professional standards for power supplies set by certification agencies based on technical specifications in the industry, including production processes, electromagnetic interference, safety protection, etc. Only products that meet certain indicators can use certification marks on packaging and product surfaces after applying for certification. Has a certain authority.
According to working methods and uses, power supplies can also be subdivided into: switching power supplies, inverter power supplies, AC stabilized power supplies, DC stabilized power supplies, DC/DC power supplies, communication power supplies, module power supplies, and variable frequency power supplies. , UPS power supply, EPS emergency power supply, purified power supply, PC power supply, rectified power supply, customized power supply, heating power supply, welding power supply/arc power supply, electroplating power supply, network power supply, electric operating power supply, adapter power supply, linear power supply, power controller/driver , power supply, other ordinary power supply, inverter power supply, parameter power supply, voltage regulating power supply, transformer power supply. In addition, there are special power supplies such as high-voltage power lamps. But in the circuit diagram, the symbol of the power supply is the same, usually marked as V.
Capacitance of the complete circuit diagram symbols
Capacitance is usually expressed as:
In circuit science, given the potential difference, the ability of the capacitor to store charge is called capacitance. Marked as C (capacitance). Using the International System of Units, the unit of capacitance is farad, marked F.
Electrolytic capacitor in circuit diagram symbols
Electrolytic capacitor is a type of capacitor. The metal foil is the positive electrode (aluminum or tantalum), and the positive electrode is close to the metal oxide film (aluminum oxide or tantalum). Tantalum pentoxide) is a dielectric. The cathode is composed of conductive material, electrolyte (electrolyte can be liquid or solid) and other materials. Because the electrolyte is the main part of the cathode, the electrolytic capacitor is named after it. At the same time, the positive and negative electrolytic capacitors cannot be connected incorrectly.
Variable capacitor in the circuit diagram symbol collection
A capacitor whose capacitance can be adjusted within a certain range is called a variable capacitor. The capacitance of a variable capacitor changes by changing the relative effective area between the pole pieces or the distance between the pole pieces. When the distance between the pole pieces changes, its capacitance changes accordingly. It is generally composed of two sets of pole pieces that are insulated from each other: the fixed set of pole pieces is called the fixed piece, and the movable set of pole pieces is called the moving piece.
Diode in a complete collection of circuit diagram symbols
A diode is a two-electrode electronic component with asymmetric conductance. An ideal diode has infinitesimal resistance between its two electrodes (anode and cathode) when conducting electricity in the forward direction, and infinite resistance when conducting electricity in the reverse direction, that is, current is only allowed to flow through the diode in one direction. Usually represented by the letter D((Diode).
Circuit Diagram Symbols Zener Diode
Generally, the voltage of a diode can be maintained at 0.7V when conducting in the forward direction, which can provide a stable voltage. But if we need a larger voltage, we need to connect a lot of diodes in series, which is not very convenient to use. If the reverse bias of the diode is very large, a collapse phenomenon will occur. This phenomenon is similar to the situation in forward conduction, and both are stable. The characteristic of voltage and steady flow, so this special diode - Zener diode was invented using this characteristic.
The name of Zener diode is also taken from the American theoretical physicist Clarence. ·Melvin Zener, who first explained the electrical collapse characteristics of insulators. Later, Bell Labs used this discovery to develop this kind of diode, and named it after Zener in commemoration, also known as "voltage diode" ".
Circuit Diagram Symbols - Tunnel Diode
The tunnel diode is a semiconductor that can switch at high speed, and its switching speed can reach the microwave frequency range. Its principle is to utilize the quantum tunneling effect. The tunnel diode was invented by Rei Ezaki in August 1958 when he was working at Tokyo Communications Industry Co., Ltd. (now Sony). In 1973, Reoina Esaki and Brian Josephson won the Nobel Prize in Physics for their discovery of the quantum tunneling effect in semiconductors.
This type of diode is formed by a highly doped PN junction (usually only 10 nanometers wide). Commonly used materials include germanium, gallium arsenide and other narrow energy gap materials. Due to high doping, The destruction of the crystal lattice causes more defects between the energy gaps. In addition, the narrow energy gap material reduces the obstacles for quantum tunneling, so it can increase the quantum tunneling current. Tunnel diodes are often used in frequency converters and detectors. Due to the negative differential resistance characteristics of tunnel diodes, they can also be used for hysteresis in oscillators, amplifiers and switching circuits.
Circuit diagram symbols: light-emitting diode
Light-emitting diode (LED) is a semiconductor electronic component that emits light. This kind of electronic component appeared as early as 1962. In the early days, it could only emit low-intensity red light. HP bought the patent and used it as an indicator light. Today, the light that LEDs can emit covers visible light, infrared and ultraviolet light, and the brightness has also been greatly improved. The uses initially evolved from indicator lights and display panels to being widely used for lighting purposes.
Light-emitting diodes can only conduct (energize) in one direction, which is called forward bias. When current flows through, electrons and holes overlap within it and emit monochromatic light, which is called the electroluminescence effect. The wavelength and color of the light are related to the type of semiconductor material used and the elemental impurities intentionally incorporated. The luminous efficiency of white LEDs has improved in recent years. In 2014, Hiroshi Amano, together with Isamu Akasaki and Shuji Nakamura, won the Nobel Prize in Physics for their "invention of high-brightness blue light-emitting diodes, which brought energy-saving and bright white light sources."
Photodiode in Circuit Diagram Symbols
A photodiode is a photodetector that can convert light into a current or voltage signal depending on how it is used. Common traditional solar cells generate electrical energy through large-area photodiodes.
Photodiodes are basically similar to conventional semiconductor diodes, except that photodiodes can be directly exposed near a light source or packaged through a transparent window or optical fiber to allow light to reach the photosensitive area of ??the device to detect light. Signal. Many diodes used to design photodiodes use a PIN junction instead of a general PN junction to increase the device's response speed to signals. Photodiodes are often designed to operate in a reverse biased state.
Circuit Diagram Symbols: Silicon Controlled Rectifier
Silicon controlled rectifier: It is a power supply based on thyristor (power electronic power device) and with intelligent digital control circuit as the core. Power control appliances.
Circuit Diagram Symbols - Varactor Diode
Varactor diode is a special diode whose junction capacitance changes significantly with the change of bias voltage. The varactor diode usually works in the reverse biased state, and changes in its bias voltage will change the thickness of the depletion layer, thus affecting the junction capacitance. This type of diode is widely used in various types of tuned circuits.
Schottky diode in the circuit diagram symbol collection
Schottky diode is a diode with low conduction voltage drop and allows high-speed switching. It uses Schottky barrier characteristics The name of the electronic component produced is to commemorate the German physicist Walter H. Schottky.
The conduction voltage of Schottky diodes is very low. A general diode will produce a voltage drop of about 0.7-1.7 volts when current flows through it, but the voltage drop of a Schottky diode is only 0.15-0.45 volts, so it can improve the efficiency of the system.
The biggest difference between Schottky diodes and general diodes is the reverse recovery time, which is the time required for the diode to switch from a conducting state through forward current to a non-conducting state.
The reverse recovery time of a general diode is about several hundred nS. If it is a high-speed diode, it will be less than one hundred nS. Schottky diodes have no reverse recovery time, so the small-signal Schottky diode switching time is about tens of pS. The switching time of special large-capacity Schottky diodes is only tens of pS. Because general diodes will cause EMI noise due to reverse current during the reverse recovery time. Schottky diodes can switch instantly without reverse recovery time or reverse current problems.
Circuit Diagram Symbols: Fuse
A fuse, also known as a fuse or a fuse, is a disposable component connected to a circuit to protect it. When the current on the circuit exceeds When it is large, the metal wires or pieces in it will generate high temperatures and melt, causing an open circuit and interrupting the current to protect the circuit from damage. After the old fuse blows, a new fuse needs to be manually replaced to restore operation of the circuit.
In order to meet the needs of circuit characteristics, fuses can be roughly divided into several categories according to their fusing rates. The types of small fuses’ fusing rates are usually represented by English letter codes: Common ones include: T (Time-lag). Slow melt type; F (Fast) represents fast melt type; M (Medium time-lag) represents medium speed; there are also TT which melts slower than T and FF which melts faster than F, etc.
Circuit diagram symbols: inductor
The inductor (inductor) will generate electromotive force due to the change of the passing current, thus resisting the change of the current. This property is called inductance, and is usually only used to refer to components whose main working condition is self-inductance or its effect. Those that are not based on self-inductance are usually called by other names, usually not called inductors, such as transformers, electromagnetic coil windings in motors, etc.
Inductive components come in many forms, with different names depending on their appearance and function. Enameled wire is wound into multiple turns and is often used as an electromagnet. Inductors used in transformers, etc. are also called coils based on their appearance. It is used to provide a large resistance to high frequency and pass through DC or low frequency. It is often called a choke coil (choke) according to its function, also known as an anti-current coil. Often combined with ferromagnetic materials, it is installed in larger inductors used in transformers, motors and generators, also called windings. The wire passes through the magnetic material without coil shape and often acts as a small inductor for high-frequency filtering. It is often called a magnetic bead based on its appearance.
Resistance in a complete collection of circuit diagram symbols
Resistance is the ability of an object to hinder the flow of electric current. A resistor refers to a device that provides this capability, usually represented by R.
Resistors are common components in electronic circuits. Actual resistors can be made of many different materials, including thin films, cement, or high-resistance nickel-chromium alloys (resistance wires).
Variable resistor in circuit diagram symbols
Variable resistor (VR, Variable Resistor), or variable resistor for short, is a device with three terminals, two of which are There are two fixed contacts and one sliding contact. It is an electronic component that can change the resistance value between the sliding end and the two fixed ends by sliding. It is a passive component. When used, it can form different voltage dividing ratios and change the potential of the sliding point, hence the name. .
As for the variable resistor (rheostat) with only two terminals (or the sliding end is connected to one of the fixed ends, and there are only two effective terminals to the outside world), it is not called a potentiometer. It can only be called a variable resistor.
Single-pole/single-throw switch in circuit diagram symbols
Single-pole/single-throw switch (SPST) refers to a switch that can open a circuit, interrupt the current, or allow it to flow to other circuits. electronic components. The most common switch is an operating switch, which has one or several electronic contacts. The "closed" state of the contact means that the electronic contact is conductive, allowing current to flow; the "open circuit" of the switch means that the electronic contact is not conductive, forming an open circuit, and does not allow current to flow.
Single-pole/double-throw switch in the circuit diagram symbol collection
Double-pole/double-throw switch in the circuit diagram symbol collection
Transformer in the circuit diagram symbol collection
< p>Transformer is a device that uses the principle of electromagnetic induction to change AC voltage. Its main components are primary coil, secondary coil and iron core (magnetic core).The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage stabilization (magnetic saturation transformer), etc.
Circuit diagram symbols: NPN transistor
A transistor is an electronic device with three terminals. The bipolar transistor is a revolutionary invention in the history of electronics. Its inventors, William Shockley, John Bardeen and Walter Bratton, were awarded the 1956 Nobel Prize in Physics.
Bipolar transistors can amplify signals and have better power control, high-speed operation and durability, so they are often used to form amplifier circuits or drive speakers, motors and other equipment.
Circuit diagram symbols: PNP transistor
Junction field effect transistor is the simplest type of unipolar field effect transistor. It can be divided into N-channel or P-channel. In the following discussion, the N-channel junction field effect transistor is mainly used as an example. In the P-channel junction field effect transistor, the N region and the P region and the positive and negative voltages and current directions are exactly reversed.
The n-channel junction field effect transistor consists of an n-type doping surrounded by a p-type doping (barrier layer). The n-type doping is connected to the drain (from the English Drain, so it is also called the D electrode) and the source (from the English Source, so it is also called the S electrode). The section of semiconductor from source to drain is called n-channel. The p area is connected to the gate (from the English Gate, so it is also called the G electrode). This pole is used to control the junction field effect transistor, which forms a pn diode with the n channel. Therefore, the junction field effect transistor is similar to the metal-oxide-semiconductor field effect transistor, except that in the metal-oxide-semiconductor field effect tube Instead of pn junction, Schottky junction (junction between metal and semiconductor) is used in the tube. In principle, junction field effect tube and metal-oxide-semiconductor field effect tube are exactly the same.
A field effect transistor (FET) is an electronic component that controls current through electric field effect. It relies on an electric field to control the shape of the conductive channel, and therefore can control the conductivity of the channel for certain types of carriers in semiconductor materials. Field-effect transistors are sometimes called "unipolar transistors" in contrast to bipolar transistors due to their single-carrier effect.
All FETs have three terminals: gate, drain, and source, which roughly correspond to the base and collector of bipolar transistors ( collector) and emitter. Except for junction field effect transistors, all FETs also have a fourth terminal, which is called body, base, bulk or substrate. This fourth terminal modulates the transistor into operation; in circuit design, the bulk terminal is rarely given a large role, but its presence is important when physically designing an integrated circuit.