Pronunciation: diàn lù
English: Circuit/Circuit
Description: (1) Path or interconnection path group that can carry current. The circuit through which direct current passes is called "direct current circuit"; The circuit through which alternating current passes is called an "alternating current circuit"
(2) the arrangement of one or more complete and closed electron flow paths.
(3) a specific part of a circuit
(4) All paths of current, including any displacement current.
(5) Combination of electronic components
Academic interpretation
A circuit is a path through which current flows.
Electrical circuit or electronic circuit is the general name of electrical equipment and components connected in a certain way, which provides a path for charge circulation. Also called electronic circuit or electrical circuit, or network or loop for short. Such as resistors, capacitors, inductors, diodes, triodes and switches.
The size of the circuit can vary greatly, from integrated circuits on silicon chips to high and low voltage transmission networks.
According to different signals, electronic circuits can be divided into analog circuits and digital circuits.
artificial circuit
The continuous physical natural quantity produced in nature converts the continuous physical natural quantity into a continuous electrical signal, and the circuit for calculating the continuous electrical signal is called an analog circuit.
Analog circuits deal with the continuous voltage and current of electrical signals.
The most typical analog circuit applications include: amplification circuit, oscillation circuit, linear operation circuit (addition, subtraction, multiplication, division, differential integration circuit). Calculate a continuous electrical signal.
digital circuit
Also known as logic circuit
A circuit that converts a continuous electrical signal into a discontinuous quantitative electrical signal and calculates the discontinuous quantitative electrical signal is called a digital circuit.
In digital circuits, signal size is a discontinuous and quantitative voltage state.
Most of them use Boolean algebraic logic circuits to process quantitative signals. Typical digital circuits include oscillators, registers, adders, subtractors, etc. Calculate discontinuous quantitative electrical signals.
integrated circuit
Integrated circuits are also called IC.
A semiconductor circuit (usually a silicon wafer) designed by using an integrated circuit design program (IC design) into a semiconductor material is called an integrated circuit.
Using semiconductor technology to manufacture integrated circuits.
Circuit composition
The circuit consists of power supply, load, connecting wire and auxiliary equipment. The actual circuit is very complicated. Therefore, in order to analyze the essence of the circuit, symbols are usually used to represent the actual components of the circuit and their connecting lines, that is, they are drawn into so-called circuit diagrams. Among them, the conductor and auxiliary equipment are collectively referred to as intermediate links.
1. power supply
A power supply is a device that provides electric energy. The function of power supply is to convert non-electric energy into electric energy. For example, batteries convert chemical energy into electrical energy; The generator converts mechanical energy into electrical energy. Because there are many kinds of non-electric energy sources and various ways to convert them into electric energy, there are also many types of practical power sources at present. The most commonly used power sources are dry batteries, storage batteries and generators.
2. Load
Various devices that use electric energy in the circuit are collectively called loads. The function of load is to convert electric energy into other forms of energy. For example, an electric furnace converts electric energy into heat energy; Motors convert electrical energy into mechanical energy, and so on. Commonly used lighting appliances, household appliances, machine tools, etc. It can be called load.
3. Conductor
Connecting wires are used to connect auxiliary equipment such as power supply and load into a closed loop, which plays the role of transmitting electric energy.
4. Auxiliary equipment
Auxiliary equipment is used to control, distribute, protect and measure circuits. Auxiliary equipment includes various switches, fuses and measuring instruments.
Circuit physical quantity
The function of the circuit is to convert electric energy into other forms of energy. Therefore, some physical quantities are used to represent the state of the circuit and the energy conversion relationship between the parts.
(1) current
Current has two practical meanings: first, current represents a physical phenomenon, that is, the regular movement of charges forms current. Secondly, the original size of current is expressed by current intensity, which refers to the amount of charge passing through the cross-sectional area of a conductor in unit time, and its unit is ampere (library/second), abbreviated as ampere, which is expressed by capital letter A, but current intensity is usually abbreviated as current. So current represents a physical quantity, which is the second meaning of current.
The true direction and the positive direction of current are two different concepts and cannot be confused.
It is customary to take the direction of positive charge movement as the direction of current, which is the actual direction or real direction of current. It exists objectively and cannot be chosen arbitrarily. In a simple circuit, the actual direction of current can be easily determined by the polarity of power supply or voltage.
However, in complex DC circuits, it is difficult to determine the true direction of current in a certain circuit in advance, while in AC circuits, the magnitude and direction of current change with time. At this time, in order to analyze the needs of calculation circuit, the concept of current reference direction is introduced, which is also called assumed positive direction.
The so-called positive direction means that in a circuit, one of the two possible real directions of current is arbitrarily selected as the reference direction (that is, assuming the positive direction). When the actual current direction is the same as the assumed positive direction, the current is positive; When the actual current direction is opposite to the assumed positive direction, the current is negative.
On the other hand, for the same circuit, because the positive direction is different, it can have different representations, which can be positive or negative. Especially, once the positive direction of the current in the circuit is determined, it must be based on it in the whole analysis and calculation process, and it is not allowed to change.
(2) Voltage and potential
Numerically, the voltage between two points AB is the work done by the electric field force to move the unit positive charge from point A to point B; The potential at a certain point in the electric field is equal to the work done by the electric field force to move the unit positive charge from that point to the reference point. Comparing the concepts of voltage and potential, we can see that the potential at a certain point in the electric field is the voltage between the point and the reference point, and the potential is a special form of voltage. The reference point is very important for electric potential. In the same circuit, when different reference points are selected, the potential value of the same point is different.
In principle, the reference point can be selected arbitrarily. In the field of electrical engineering, the grounding point in the circuit is usually selected as the reference point, and in the electronic circuit, the shell is usually selected as the reference point.
In practical application, it is often not enough to know the voltage between two points, but also need to know which potential is higher and which potential is lower. For example, for a semiconductor diode, it is not turned on until the anode potential is higher than the cathode potential; For DC motor, the rotating direction of the motor may be different because of the different potentials at both ends of the winding. Due to the need of practical use, we are required to introduce the polarity of voltage, that is, the direction problem.
(3) electromotive force
(4) Electricity
(5) Voltage is positively related to current.
Circuit state
1. Open circuit is also called open circuit, because the resistance of a certain part of the circuit is too large due to interruption, and the current in the circuit cannot pass normally, resulting in zero current, and the voltage at both ends of the interruption point is the power supply voltage, which is generally harmless to the circuit.
2. The short-circuit power supply is directly connected to the closed loop through wires, without passing through the load.
3. Normal load state
Circuit law
All circuits follow some basic circuit laws.
Kirchhoff's current law: the sum of currents flowing into the node is equal to the sum of currents flowing out of the node.
Kirchhoff's voltage law: the sum of loop voltages is zero.
Ohm's Law: The voltage across a linear element (such as a resistor) is equal to the product of the resistance of the element and the current flowing through the element.
Norton Theorem: Any two-terminal network composed of voltage source and resistor can always be equivalent to a parallel network of ideal current source and resistor.
Thevenin theorem: Any two-terminal network composed of a voltage source and a resistor can always be equivalent to a series network of an ideal voltage source and a resistor.
The analysis of circuits containing nonlinear devices requires some more complicated laws. In the actual circuit design, circuit analysis is more done by computer analysis and simulation.
Circuit power
When all circuits are working, each component or line will have energy utilization, that is, electric energy utilization. The electric energy utilization in all circuits is called circuit power.
The power of a circuit or circuit element is defined as: power = voltage * current (P=I*V).
In nature, energy is immortal, and there is an inherent law of energy immortality.
Total circuit power = circuit power+power of each circuit element. For example: power supply (I*V)= circuit (I*V)+ component (I*V)
The energy in the circuit will sometimes be converted into heat energy or radiation energy ... and other energy will enter the air, which is why the circuit or circuit components will generate heat, and not all of them will form electric energy in the circuit. According to energy, total energy = electric energy+thermal energy+radiant energy+other energy.
Circuit type
Power supply circuit: the power supply needed to generate various electronic circuits.
Electronic circuit: Also called circuit.
Frequency category
Fundamental frequency circuit, fundamental frequency, low frequency, using fundamental frequency components.
High frequency circuit, high frequency, high frequency, using high frequency components.
Fundamental frequency and high frequency mixed circuit
Component type
Passive components: such as resistors, capacitors, inductors, diodes, etc. There are fundamental frequency passive components and high frequency passive components.
Active components: such as transistors and microprocessors. It is divided into fundamental frequency active component and high frequency active component.
Usage type
Microprocessor circuit: also known as microcontroller circuit, it constitutes computers, game machines, (player audio and video), various household appliances, mice, keyboards, touch control and so on.
Computer circuit: it is the advanced circuit of microprocessor circuit, which constitutes desktop computer, notebook computer, palmtop computer, industrial computer and so on.
Communication circuit: telephone, mobile phone, wired network, wired transmission, wireless network, wireless transmission, optical communication, infrared ray, optical fiber, microwave communication, satellite communication, etc.
Display circuit: form screen, TV and instrument! And other displays.
Photoelectric circuit: such as solar circuit.
Motor circuit: commonly used in high-power equipment, such as power equipment, transportation equipment, medical equipment, industrial equipment, etc.