The circuit through which current flows is called an electric circuit, also known as a conducting circuit.
Circuits
According to a certain task, the required devices, connected by wires, that is, to form a circuit. Circuit is a power system, control systems, communication systems, computer hardware and other electrical systems, the main component of the electrical system, plays a role in the generation of electrical energy and electrical signals, transmission, conversion, control, processing and storage.
The simplest circuit is made up of three parts: a power supply, an electrical appliance (load), and an intermediate link (wires, switches, and other components). [7] When a circuit is on, it is called a through circuit, and when it is off, it is called an open circuit. Only when a circuit is open, current passes through it. A break in a circuit is called a break or an open circuit. If there is no load between the positive and negative terminals of the power supply in the circuit, it is called a short circuit, which is never allowed. Another type of short circuit is a component of the two ends directly connected, then the current from the direct connection will not flow through the component, this situation is called the component short-circuit. Open circuit (or broken circuit) is allowed, but the first short circuit is never allowed, because the short circuit of the power supply will lead to power supply burned out, the short circuit of the electrical appliances will lead to electrical appliances, meters, etc. can not work properly phenomenon occurs.
Professional understandingCircuits are paths through which current flows, or electronic circuits, are made of electrical equipment and components (appliances), connected in a certain way. Such as resistors, capacitors, inductors, diodes, transistors, power supplies and switches, etc., constitute the network.
The size of the circuit can vary greatly, from small integrated circuits on silicon wafers to high and low voltage transmission grids. Depending on the signal being processed, electronic circuits can be divided into analog and digital circuits.
Analog circuits
Converting the continuity of physical natural variables into continuous electrical signals and operating the continuity of electrical signals through the circuit is called an analog circuit. Analog circuits process the continuity voltages and currents of electrical signals.
The most typical applications of analog circuits include: amplifying circuits, oscillating circuits, and linear arithmetic circuits (addition, subtraction, multiplication, division, differentiation, and integration circuits). Operate on continuous electrical signals.
DIGITAL CIRCUITSDigital circuits are also known as logic circuits
Circuits that convert electrical signals of continuity into electrical signals of discontinuity quantization and operate electrical signals of discontinuity quantization are called digital circuits.
In digital circuits, the size of the signal is a discontinuous and quantized voltage state.
Most of the Boolean algebraic logic circuits are used to process the quantized signal. Typical digital circuits are, oscillators, registers, adders, subtractors, etc.. Operational discontinuity quantized electrical signals.
-Integrated circuits are also known as IC (Integrated Circuit).
-Semiconductor circuits (generally silicon wafers), which are designed into semiconductor materials using integrated circuit design programs (IC design), are called integrated circuits. -Using semiconductor technology to create integrated circuits (ICs).
Types and Concepts-Power circuits: generate the required power supply for various electronic circuits.
-Electronic circuits: also known as electrical circuits.
-Base Frequency Circuit, base frequency, low frequency, using base frequency components.
-High-frequency circuits, high-frequency, high-frequency, using high-frequency components.
-Passive components: such as resistors, capacitors, inductors, diodes ... etc., there are base frequency passive components, high frequency passive components.
-Active components: such as transistors, microprocessors ... and so on, there are base-frequency active components, high-frequency active components.
Microprocessor circuits: also known as microcontroller circuits, forming computers, game consoles, (player video, audio), a variety of home appliances, mice, keyboards, touch ... ... and so on.
Computer circuits: Advanced microprocessor circuits for desktop computers, notebook computers, handheld computers, industrial computers, and other computers.
Communication circuits: Formation of telephone, cellular phone, wired network, wired transmission, wireless network, wireless transmission, optical communication, infrared, fiber optic, microwave communication, satellite communication, and so on.
Display circuit: the formation of the screen, TV, meters and other types of displays.
Optoelectronic circuits: such as solar energy circuits.
Motor circuits: Often used in large power supply equipment, such as electric power equipment, transportation equipment, medical equipment, industrial equipment...etc.
Invention of the Integrated CircuitJack S. Kilby, father of the integrated circuit
On September 12, 1958, Kilby developed the world's first integrated circuit.
Birth of an Invention
In 1947, University of Illinois graduate Jack S. Kilby took a job in Milwaukee, Wisconsin, with a keen interest in electronics, making components for radios, televisions, and hearing aids for an electronics supplier. Outside of work, he took night classes for a master's degree in electrical engineering at the University of Wisconsin. Of course, the combination of work and classes can be a challenge for Kilby, but he says, "This thing can be done, and it's really worth the effort."
After earning his master's degree, Kilby and his wife moved to Dallas, Texas, to work for Texas Instruments, which was the only company that allowed him to spend nearly all of his time researching the miniaturization of electronic devices, providing him with plenty of time and good experimental conditions. Kilby was a gentle, soft-spoken man who, at 6 feet 6 inches tall, was known to his assistants and friends as "the gentle giant". It was this unassuming giant who conceived a titanic idea. Texas Instruments at the time had a tradition of granting employees two weeks of vacation during the hot month of August. But Kilby, who was new to the company, had no chance of a long vacation and had to stay in the cold workshop to study alone. During this time, he gradually developed a genius idea: resistors and capacitors (passive components) could be made from the same materials as transistors (active devices). Also, since all components could be made from the same material, these parts could be made in situ on the same material before being connected to each other to eventually form complete circuits. He chose the semiconductor silicon.
"I sat at my desk and stayed a little later than usual, it seems." He recalled in a 1980 interview, "The whole idea actually took shape roughly that day, and then I organized all the ideas and drew up some designs in my notebook. When my supervisor came back, I showed him the plans. At that time, although some people were slightly skeptical, they basically understood the importance of this design." So, we go back to the scene at the beginning of the article, the day the company's supervisor came to the lab and wired up a test line with this giant. The test was successful. Texas Instruments soon announced that they had invented the integrated circuit, for which Kilby filed a patent. The silicon era was ushered in. At the time, he probably didn't really realize the value of this invention. After winning the Nobel Prize, he said, "I knew that my invention of the integrated circuit was very important to the electronics industry, but I never imagined that it would be as widely used as it is today."
Impact
Integrated circuits replaced transistors, paving the way for the development of a wide range of functions in electronics and drastically reducing costs, and the third generation of electronics has since taken the stage. Its birth made possible the emergence of microprocessors and turned computers into everyday tools that ordinary people could get close to. The application of integrated technology has given birth to more convenient and fast electronic products, such as the common hand-held electronic calculator, is Kilby following the integrated circuit after a new invention. To this day, silicon remains the primary material for our electronics.
Nobel Prize
In 2000, 42 years after the introduction of the integrated circuit, the value of Kilby and his inventions was finally recognized, and he was awarded the Nobel Prize in Physics. The Nobel Prize jury once commented that Kilby "laid the foundation for modern information technology. "In 1959, Robert Royce of Fairchild Semiconductor filed for a more complex silicon integrated circuit, which was immediately put into commerce. However, Kilby filed the patent first, and as a result, Royce is considered the *** same inventor of the integrated circuit. Royce died in 1990, a brush with the Nobel Prize. Jack Kilby was rather modest, holding more than sixty patents in his lifetime, but in his acceptance speech he said, "My work may have introduced a new perspective on looking at circuit components and created a new field, and most of what has been accomplished since then is not directly related to my work.
Components of an electric circuitA circuit consists of four main parts: a power supply, a switch, connecting wires, and electrical appliances. Since circuits in practice are complex, in order to make it easier to analyze the essence of a circuit, it is common to use symbols to represent the actual components of the circuit and their connecting wires in what is known as a circuit diagram. The wires and auxiliary equipment are called intermediate links.
A power supply is a device that provides electrical energy. The function of a power supply is to convert non-electrical energy into electrical energy. For example, a battery converts chemical energy into electrical energy; a generator converts mechanical energy into electrical energy. Since there are many types of non-electrical energy, there are many ways to convert it into electrical energy. Power supply is divided into two kinds of voltage source and current source, only the same size of the voltage source is allowed to be connected in parallel, and likewise only the same size of the current source is allowed to be connected in series, the voltage source can't be short-circuited, and the current source can't be disconnected.
The various devices that use electrical energy in a circuit are collectively known as loads. The function of the load is to convert electrical energy into other forms of energy. For example, the electric furnace to electrical energy into thermal energy; electric motor to electrical energy into mechanical energy, and so on. Usually used lighting appliances, household appliances, machine tools, etc. can be called loads.
Connecting wires are used to connect the power supply, loads and other auxiliary equipment into a closed circuit, and play a role in transferring electrical energy.
Auxiliary equipment Auxiliary equipment is used to realize the control, distribution, protection and measurement of the circuit. Auxiliary equipment includes various switches, fuses, ammeters, voltmeters and measuring instruments.
Series CircuitsSeries connection is one of the basic ways of connecting circuit components. The circuit components (such as resistance, capacitance, inductance, electrical appliances, etc.) are connected one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one, one by one.
-Switches control the entire circuit from any position, i.e., their action is independent of their position. There is only one path for the current; the current that passes through one lamp must pass through the other lamp. If one lamp is extinguished, the other lamp must be extinguished.
-Advantages: In a circuit, if you want to control all the electrical appliances through a switch, you can use a series circuit;
-Disadvantages: As long as there is a break in one place, the whole circuit will become broken. This means that the electronic components connected in series will not work properly.
The total resistance in a series circuit is equal to the sum of the resistances of the electronic components, the currents are equal everywhere, and the total voltage is equal to the sum of the voltages everywhere.
Parallel CircuitsParallel circuits are circuits in which there is more than one mutually independent path for the current between the circuit elements that form a parallel connection, and are one of the two basic ways in which circuits are formed. For example, a simple circuit containing two light bulbs and a 9 V battery. If the two bulbs are connected to the battery by two separate sets of wires, the two bulbs are connected in parallel.
Features: the appliances do not affect each other. If an appliance on one branch circuit is damaged, the other branches are not affected.
Physics in electrical circuits
The function of electrical circuits is to carry out the interconversion between electrical energy and other forms of energy. Therefore, a number of physical quantities are used to represent the state of the circuit and the interrelationship of the energy conversions between its parts.
Meaning of currentCurrent has two meanings in practical terms: first, current denotes a physical phenomenon, i.e., the regular movement of electric charge forms current. Second, originally, the size of the current with the current intensity to express, and the current intensity is the amount of charge through the cross-sectional area of the conductor in a unit of time, the unit is amperage (ku/sec), referred to as ampere, with a capital letter A said. But the current intensity usually people more short for current. So the current also represents a physical quantity, which is the second meaning of current.
Direction of currentThe true direction and the positive direction of the current are two different concepts and should not be confused.
It is customary to always take the direction of the positive charge movement, as the direction of the current, which is the actual or real direction of the current, which is objective and can not be chosen arbitrarily, in simple circuits, the actual direction of the current can be easily determined by the polarity of the power supply or voltage.
But in complex DC circuits, the real direction of the current in a section of the circuit is difficult to determine in advance, in AC circuits, the size and direction of the current are changing with time. At this point, in order to analyze and calculate the needs of the circuit, the introduction of the concept of the current reference direction, the reference direction is also called the assumption of the positive direction, referred to as the positive direction.
The so-called positive direction is in a section of the circuit, in the current two possible real direction, arbitrarily choose one as the reference direction (i.e., assumed 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.
To put it another way, for the same circuit, can be due to the selection of the positive direction of the different and there is no comparison between the concept of voltage and potential can be seen, the potential of a point in the electric field is the point to the reference point of the voltage between the potential is a special form of voltage with the same representation, which may be a positive or negative value. It is important to note that the positive direction of the current in the circuit, once determined, must be used as a criterion throughout the process of analysis and calculation, and is not allowed to change.
Numerically, the voltage between the two points AB is the work done by the electric field force in moving the unit positive charge from point A to point B. The potential at a point in the electric field is equal to the work done by the electric field force in moving the unit positive charge from that point to the reference point. For the potential, the reference point is crucial. The value of the potential at the same point in the same circuit is different when different reference points are selected.
In principle, the reference point can be chosen arbitrarily. In the field of electrical engineering, it is common to choose the grounding point in a circuit as the reference point, and in electronic circuits, the chassis is often taken as the reference point.
In practice, only know the voltage between the two points is often not enough, but also required to know which of the two points in which the potential is high, which point is low. For example, for the semiconductor diode, there is its anode potential is higher than the cathode potential before conduction; for the DC motor, the winding ends of the potential is different, the direction of rotation of the motor may be different. Because of the need for practical use, we are required to introduce the polarity of the voltage, that is, the direction of the problem.
The difference in potential in an electric circuit due to the conversion of other forms of energy into electrical energy is called electric potential. It is represented by the letter E in volts. In electrical circuits, the electric potential is often represented by the symbol δ.
In physics, electric power is used to indicate the speed of consumption of electrical energy. Electric power is expressed in P, which is the unit of watts, referred to as watt, the symbol is W. The work done by the current in a unit of time is called the electric power Take a light bulb as an example, the higher the electric power, the brighter the light bulb. The brightness of the bulb is determined by the actual electric power, not by the current, voltage, electrical energy, resistance through the decision! [5]?
Important LawsOhm's Law: In the same circuit, the current in a conductor is directly proportional to the voltage at the ends of the conductor and inversely proportional to the resistance of the conductor, the basic formula is I=U/R (current=voltage/resistance)
Norton's Theorem: Any two-terminal network consisting of a voltage source with a resistor can always be equated to a parallel network of an ideal current source with a resistor.
Davinin's theorem: any two-terminal network consisting of a voltage source and a resistor can always be equated to a series network of an ideal voltage source and a resistor.
Analyzing circuits containing nonlinear devices requires some more complex laws. In practical circuit design, circuit analysis is more often done by computer analysis simulation.
It is an important theorem for linear components. In a linear resistor, the voltage or current somewhere is a superposition of the voltages or currents that would be generated at that location by each of the separate power sources in the circuit when acting individually.
For a circuit with n nodes and b branches, assuming that the individual branch currents and branch voltages take the correlated reference direction and letting (i1,i2,----,ib), (u1,u2,----,ub) be the currents and voltages of the b branches, respectively, there is i1*u1+i2*u2+-+-+ib*ub=0 for any time t.
In a dyadic circuit, certain relationships (or equations) between elements can be interchanged by swapping the elements of the dyad. Pairwise elements include the topology of the circuit, circuit variables, circuit elements, some circuit formulas (or equations) and even theorems.
When all circuits work, every element or line has a working use of energy, i.e., electrical energy use, and the working use of electrical energy in all circuits is called circuit power.
The power of a circuit or circuit element is defined as: Power = Voltage * Current (P = I * V).
Energy is not destroyed in nature, there is a law of conservation of energy.
Total circuit power = circuit power + power of each circuit element. For example: Power (I*V) = Circuit (I*V) + Components (I*V)
Energy in a circuit sometimes becomes heat or radiant energy...and other energy into the air, which is the reason why the circuit or the circuit components will heat up, and will not all be formed in the circuit of electrical energy, there is a total energy = electrical energy + thermal energy + radiant energy + other energy.
Series circuits
1. The current is equal everywhere: I total = I1 = I2 = I3 = ......=In
2. The total voltage is equal to the sum of the voltages everywhere: U total = U1 + U2 + U3 + ......+ Un
3. Equivalent resistance is equal to the sum of the resistances: R total = R1 + R2 + R3 + ...... + Rn
(Increase in electrical appliances is equivalent to an increase in the length, increase in resistance)
4. The total power is equal to the sum of the power: P total = P1 + P2 + P3 + ...... + Pn
5. The total power is equal to the sum of the power: P total = P1 + P2 + P3 + ...... = In
6. ......+Pn
5. The total electric power is equal to the sum of the electric power: W1+W2+......+Wn
6. The total electric heat is equal to the sum of the electric heat: Q1+Q2+...+Qn
7. The total electric heat is equal to the sum of the electric heat: Q1+Q2+ ...+Qn
8. ...+Qn7. The reciprocal of the equivalent capacitance is equal to the sum of the reciprocals of the capacitances of the individual capacitors: 1/C total = 1/C1 + 1/C2 + 1/C3 + ...... + 1/Cn
8. Voltage distribution, work of power, electric power, and rate of heat are proportional to the resistance proportional to resistance: (t is the same)
U1/U2=R1/R2, W1/W2=R1/R2, P1/P2=R1/R2, Q1/Q2=R1/R2. or written as U1/U2=W1/W2=P1/P2=Q1/Q2=R1/R2
9. To control all the electrical appliances in an electric circuit, you can use a series circuit.
Parallel circuits
1. The voltages at the ends of each branch are equal and equal to the voltages at the ends of the power supply:
Total U = U1 = U2 = U3 = ...... = Un;
2. The main current (or total current) is equal to the sum of the currents in each branch:
I Total = I1 +I2 +I3 +......+In;
3. The reciprocal of the total resistance is equal to the reciprocal sum of the resistance of each branch:
1/R Total = 1/R1 + 1/R2 + 1/R3 + ......+1/Rn or written as: R=1/(1/(R1+R2+R3+......+Rn));
(Increasing electrical appliances is equivalent to increasing the cross-sectional area and decreasing the resistance)
4. The total power is equal to the sum of the individual powers:
Total P=P1+P2+P3+.... ...+Pn;
5. The total electric power is equal to the sum of the individual electric powers: W total=W1+W2+......+Wn
6. The total electric heat is equal to the sum of the individual electric powers: Q total=Q1+Q2+...... +Qn
7. Equivalent capacitance is equal to the sum of the capacitance of each capacitor: C total = C1 + C2 + C3 + ...... + Cn
8. If you want to control an appliance individually in an electric circuit, you can use a parallel circuit.