Electronics short course of lectures. Electric circuit with parallel connection of elements. Compiled by – Vasiliev D.Yu
St. Petersburg, Corona-Print, 1998, 399 p.
DjVu.
Description The course of lectures on electronics offered to the attention of readers corresponds to the programs of a number of disciplines “Electronics”, “Electrical engineering and fundamentals of electronics”, “ Electronic equipment", "Power supply of electronic devices". This book is a continuation and development of the textbook “Electrical Engineering and Fundamentals of Electronics” (ed. “ graduate School", M., 1996), written by the author together with prof. T. A. Glazenko and recommended by the Ministry of General and vocational education Russian Federation as a teaching aid.
Unlike the previous book tutorial on electronics was written in the form of a course of lectures, which the author read for a number of years to students of the St. Petersburg State Institute of Precision Mechanics and Optics (Technical University). This form of presenting material has certain advantages.
- the volume of each lecture is designed for an average of four academic hours and can be reduced if the time allocated for studying the material is limited;
- the number of lectures is designed to study the discipline during a semester (17-18 weeks) or two semesters (34-36 weeks);
-each lecture can be studied independently of the previous ones, since there are practically no cross-references in the book;
The lectures are thematically combined into seven sections, including such as “Electronic elements”, “Electronic devices” and “Power supplies for electronic devices”.
The lectures contain carefully selected illustrations that can be used as educational visual aids. Many lectures contain reference tables giving characteristics of the most advanced modern electronic elements and devices.
Studying the electronics course assumes that readers have knowledge of elementary mathematics, some sections of higher mathematics and algebra of logic, the basics of the theory of electrical circuits and solid state physics. If the reader has any problems in this regard, we can recommend studying the appropriate section on specialized literature, including the textbook mentioned above, written with the participation of the author.
The lectures do not contain references to the literature that the author used when writing the book, however, for an expanded study of individual sections or topics, a list of literature recommended by the author is provided at the end of the book.
Secondly, they lack material (including reference) about the latest achievements in the field of power electronics and microcircuitry.
When writing this book, the author tried to eliminate these shortcomings by limiting the volume to the number of lectures and including in the book lectures on power semiconductor devices and the limiting modes of their operation, modern analog and digital electronics analog multipliers, control microcircuits for switching power supplies and power factor correctors, digital storage devices, etc.
The book may be useful to middle and high school students educational institutions, studying the disciplines “Electronics” and “Electrical engineering and fundamentals of electronics”, as well as related disciplines “Secondary power sources”, “Digital and pulsed devices”. In addition, the book can be used by specialists in the field of computer technology, radio electronics and automation who are involved in the selection or development of electronic devices for various purposes.
(Document)
n1.doc
Short course of lectures
in electrical engineering (correspondence department)
Introduction
Basic definitions
1.1. Basic explanations and terms
1.2. Passive equivalent circuit elements
1.3. Active elements equivalent circuits
1.4. Basic definitions related to schemas
1.5. Operating modes of electrical circuits
1.6. Basic laws of electrical circuits
Equivalent circuit transformations. Parallel connection of electrical circuit elements
2.1. Serial connection of electrical circuit elements
2.2. Parallel connection of electrical circuit elements
3.1. Calculation of DC electrical circuits
single source coagulation method
4.1. Method of direct application of Kirchhoff's laws
4.2. Loop current method
4.3. Nodal potential method
Nonlinear DC electrical circuits
5.1. Basic definitions
5.2. Graphical method calculation of nonlinear DC circuits
Electrical circuits of single-phase alternating current
6.1. Basic definitions
6.2. Representation of sinusoidal time functions in vector form
6.3. Representation of sinusoidal time functions in complex form
6.4. Resistance in a sinusoidal current circuit
6.5. Inductive coil in a sinusoidal current circuit
6.6. Capacitance in a sinusoidal current circuit
6.7. Series connected real inductive
coil and capacitor in a sinusoidal current circuit
6.8. Parallel connected inductance, capacitance and
active resistance in a sinusoidal current circuit
6.9. Resonant mode in a circuit consisting of parallel
included real inductive coil and capacitor
6.10. Power in a sinusoidal current circuit
Three-phase circuits
7.1. Basic definitions
7.2. Star connection. Scheme, definitions.
7.3. Triangle connection. Scheme, definitions
7.5. Power in three-phase circuits
Magnetic circuits
9.1. Basic definitions
9.2. Properties of ferromagnetic materials
9.3. Calculation of magnetic circuits
Transformers
10.1. Transformer design
10.2. Operation of the transformer in idle mode
10.3. Transformer operation under load
DC Electrical Machines
11.1. Design of a DC electric machine
11.2. Operating principle of a DC machine
11.3. Operation of DC electric machine
in generator mode
11.4. Generators with independent excitation.
Generator characteristics
11.5. Self-excited generators.
The principle of self-excitation of a generator with parallel excitation
11.6. Operation of DC electric machine
in engine mode. Basic Equations
11.7. Mechanical characteristics of electric motors
direct current
AC Electrical Machines
12.1. Rotating magnetic field
12.2. Asynchronous motors. Design, principle of operation
12.3. Torque of asynchronous motor
12.4. Speed control asynchronous motors.
Reversing an asynchronous motor
12.5. Single-phase asynchronous motors
12.6. Synchronous motors.
Design, principle of operation
Introduction
Electrical engineering is a branch of science and technology associated with the use of electrical and magnetic phenomena for energy conversion, materials processing, information transmission, etc.Electrical engineering covers the issues of obtaining, converting and using electricity in practical human activities. Electricity can be obtained in significant quantities, transmitted over a distance and easily converted into other types of energy.
A short course of lectures provides basic definitions and topological parameters of electrical circuits, outlines methods for calculating linear and nonlinear DC and AC circuits, analysis and calculation of magnetic circuits.
The design, principle of operation and characteristics of transformers and electrical machines of direct and alternating current, as well as information electrical machines, are considered.
1. Basic definitions
1.1. Basic explanations and terms
Electrical engineering is a field of science and technology that studies electrical and magnetic phenomena and their use for practical purposes.An electrical circuit is a collection of devices designed to produce, transmit, transform and use electric current.
All electrical devices according to their purpose, principle of operation and design can be divided into three groups:
Energy sources, i.e. devices that produce electric current (generators, thermoelements, photocells, chemical elements).
Receivers, or load, i.e. devices that consume electric current (electric motors, electric lamps, electrical mechanisms, etc.).
Conductors, as well as various switching equipment (switches, relays, contactors, etc.).
Electric current, the magnitude and direction of which does not remain constant, is called variables electric shock The value of the alternating current at the considered moment in time is called instantaneous and is denoted by the lowercase letter i.
For an electrical circuit to operate, it is necessary to have energy sources.
There are active and passive circuits, sections and elements of circuits. Active are electrical circuits containing energy sources, passive are electrical circuits that do not contain energy sources.
An electrical circuit is called linear if not a single parameter of the circuit depends on the magnitude or direction of the current or voltage.
An electrical circuit is nonlinear if it contains at least one nonlinear element. The parameters of nonlinear elements depend on the magnitude or direction of current or voltage.
The electrical circuit is graphic image electrical circuit, including symbols of devices and showing the connection of these devices. In Fig. Figure 1.1 shows an electrical diagram of a circuit consisting of an energy source, electric lamps 1 and 2, and electric motor 3.
To facilitate analysis, the electrical circuit is replaced with an equivalent circuit.
Substitution scheme
is a graphic representation of an electrical circuit using ideal elements, the parameters of which are the parameters of the replaced elements.
Figure 1.2 shows the equivalent circuit.
AUTONOMOUS NON-PROFIT ORGANIZATION
HIGHER PROFESSIONAL EDUCATION
CENTRAL UNION OF THE RUSSIAN FEDERATION
"RUSSIAN UNIVERSITY OF COOPERATION"
KAZAN CO-OPERATIVE INSTITUTE (BRANCH)
ELECTRICAL AND ELECTRONICS
LECTURE NOTES
for students studying in the field of preparation
222000.62 Innovation,
260800.62 Product technology and catering organization
Kazan 2013
Kirsanov V.A. Electrical engineering and electronics: Lecture notes - Kazan: Kazan Cooperative Institute (branch) of the Russian University of Cooperation, 2013. - 9 p.
Lecture notes for students studying in the field of study 222000.62 Innovation, 260800.62 Product technology and catering organization were developed in accordance with the curriculum approved by the Academic Council of the Russian Cooperation University dated 02/15/2013, protocol No. 3, and the work program dated 09/11/2013 d, protocol No. 1.
© Kazan Cooperative Institute (branch) of the Russian University of Cooperation, 2013
© Kirsanov V.A., 2013
Lecture 1. General concepts and definitions of electrical circuits
electrical and Electronics – a discipline that combines knowledge about two interrelated branches of science and technology: electrical engineering and electronics. Combining the two disciplines allows us to better understand their relationship and more competently use the physical foundations of electromagnetic phenomena studied in electrical engineering and methods for calculating electrical circuits in the analysis and synthesis of electronic circuits that use both linear and nonlinear electronic devices and components.
Electrical engineering – branch of science and technology related to obtaining,
transformation and use of electrical energy in practical human activity, covering issues of the use of electromagnetic phenomena in various industries and in everyday life.
Electronics – a branch of science and technology associated with the creation and description of the physical principles of operation of new electronic instruments and devices or electronic circuits based on them.
Purpose of the discipline:
Study of the basic laws and methods of calculating linear electrical and magnetic circuits;
Studying methods of analysis and synthesis of linear and nonlinear electrical circuits;
Studying the principles of operation of transformers, electrical machines of direct and alternating current;
Studying the organization of network power supply;
Study of methods for measuring and observing electrical signals;
Study of the operating principles of basic semiconductor devices and basic circuits electronics created on their basis;
Studying the element base modern computers and other electronic devices;
Studying the principles of organization of linear amplifiers of electrical signals, including operational amplifiers, and studying the areas of their possible application;
Studying the principles of constructing power supplies for modern electronic devices.
General information
Electrical circuit is a collection of interconnected elements, components or devices designed to pass through them electric current, the processes in which can be described using the concepts of electromotive force (emf), electric current and electric voltage.
Electric current (i or I) – directional movement of electric charge carriers (which are often electrons). There are three types of current: conduction current, displacement current, transfer current. Conduction current is caused by the directed, ordered movement of free charge carriers (for example, electrons) under the influence of an electric field inside the conductor. The displacement current or polarization current is observed in the dielectric and is caused by the displacement relative to each other under the influence of the electric field of connected charges of opposite sign. Under the influence of a constant external electric field, a short-term displacement current is observed. But with an alternating field, the displacement current has to be taken into account. The transfer current or convection current is caused by the transfer of electric charges in free space by charged particles or bodies under the influence of an electric field.
A quantitative characteristic of electric current is current strength - the amount of electricity q that flows through the cross section of the conductor per unit time:
I= q/t.
If the charges move unevenly in the conductor, the changing current strength can be found using the formula:
i = dq / dt.
The amount of electricity in the SI system is measured in coulombs (C), and current is measured in amperes (A).
An ampere is the force of a constant current which, passing through two parallel straight conductors of infinite length and negligible circular cross-section, located at a distance of 1 m from each other in a vacuum, would produce between these conductors a force equal to 1 N/m.
A coulomb is defined as the amount of electricity flowing through a cross-section of a conductor in 1 s at a constant current of 1 A.
To characterize the movement of electricity at a given point on the surface, current density δ is used, which is determined by the formula:
δ = I/S,
where S is the cross-sectional area of the conductor.
Electrical voltage (u or U) – the difference in electrical potential between selected points or the amount of work that an electric field will do to transfer a single positive charge from one point to another.
The electric potential is numerically equal to the work of the field in transferring a unit positive charge from a given point in space to an infinitely distant one, the potential of which is taken to be zero. Since in an electrical circuit the potential of one of the points is assumed to be zero, electrical voltages are usually of interest, not potentials.
1B=1J/1Coulomb
Emf source – a voltage source in the electrical circuit, the magnitude of which depends little on the load selected within reasonable limits; a source of electrical energy that uses third-party, non-electrical forces to generate external voltage. Example: a galvanic cell that converts chemical energy into electrical energy and a generator that converts mechanical energy into electrical energy.
Electrical diagram – a method of depicting an electrical circuit on a plane using conventional graphic designations ̆ components or elements of the electrical circuit. A schema is often understood as physical implementation electrical circuit.
Component, element – minimal, functionally and structurally complete component circuits or circuits. Components include power supplies, electric motors, resistors, capacitors, and inductors.
When analyzing electrical circuits, as a rule, the value of currents, voltages and powers is assessed. In this case, there is no need to take into account the specific device of various loads. It is important to know only their resistance - R, inductance - L or capacitance - C. Such circuit elements are called receivers of electrical energy.
The dependence of the current flowing through a receiver of electrical energy on the voltage at this receiver is usually called current-voltage characteristic (volt-ampere characteristic).
Receivers of electrical energy whose current-voltage characteristics are straight lines are called linear.
Electric circuits that include only linear elements are called linear electrical circuits.
Electric circuits that include at least one nonlinear element are called nonlinear electrical circuits.
Signal – a physical process that carries information or is of interest.
Electrical signal – a signal in the form of electrical voltage or current. Distinguish analog and digital (discrete) signals.
Analog signal can take any arbitrary value of voltage or current within a given permissible range from minimum value to the maximum.
Sensor – a converter of a physical process of interest and carrying information into an electrical signal. An example of a sensor is a thermocouple (an alloy of two dissimilar materials), which generates an output voltage proportional to the temperature. Example: Hall Sensor, which converts the magnitude of the magnetic induction of the external magnetic field into emf, that is, into an analog signal; thermistor, converting ambient temperature into resistance; strain gauge, carrying out the transformation mechanical pressure into resistance.
Digital signal – presentation of digital information in the form of clearly distinguishable voltage levels. To represent binary information in which only two values are possible: 0 or 1, it is sufficient to use two clearly distinguishable voltage levels. There are several ways to represent a binary signal: potential, impulse and impulse-potential.
At potential method of representation, logic states 0 and 1 are represented by two different voltage levels. For example, for transistor-transistor logic (TTL) elements:
A logical unit is represented by a voltage U 1 ≥ 2.4V;
Logical zero is represented by voltage U 0 ≤ 0.4V.
At pulse In the representation of binary information, a logical one corresponds to the presence of a pulse or a series of pulses at the output of an element, and a zero – the absence of pulses.
Pulse – an electrical signal characterized by a rapid change in voltage or current level and which typically tends to establish one of two possible voltage or current limits.
At impulse-potential When presenting information, both methods proposed above are used simultaneously.
Logic element - the smallest functionally and structurally complete part of a computer that performs any logical function. Among the main logical functions, they usually include disjunction, conjunction and negation.
Disjunction is a function (y) of binary variables (X1, X2, ..) that is equal to one when at least one input variable is equal to one. A function for two variables is written as follows:
y=X1vX2.
Disjunction is implemented using a disjunctor or an element of type NIOR, where N is the number of inputs to the disjunctor. With two inputs, we are dealing with the 2OR element, the symbol of which is suggested in the figure:
Conjunction– such a function (y) of binary variables (X1, X2, ..), which is equal to one when all input variables are equal to one. A function for two variables is written as follows:
y=X1&X2 or y=X1*X2.
Conjunction is implemented using a conjunctor or an element of type NI, where N is the number of inputs to the conjunctor. With two inputs, we are dealing with element 2I, the symbol of which is suggested in the figure:
Negation– such a function (y) of the binary variable X, which is equal to one if the input variable is equal to zero and vice versa.
Negation is implemented using an inverter or a NOT element, the symbol of which is suggested in the figure:
The negation symbol in the symbol is a circle on the signal line.
Magnetic circuit are a set of devices containing ferromagnetic bodies and forming a closed circuit in which, in the presence of a magnetomotive force, a magnetic flux is formed and along which the lines of magnetic induction are closed.
Magnetomotive force (mf) – characteristics of the sources’ ability magnetic field(electric currents) create magnetic fluxes.
Lecture 2. DC electrical circuits
Basic laws of DC circuits
The basic topological concepts of the theory of electrical circuits are branch, node, circuit, two-terminal network, four-terminal network, circuit graph of electrical circuits, circuit graph tree. Let's look at some of them.
Branch called a section of an electrical circuit with the same current. It may consist of one or more elements connected in series.
Knot called the junction of two elements. The junction of three or more branches is called a complex node. A complex node is indicated on the diagram by a dot. Complex nodes having equal potentials are combined into one potential node.
Outline called a closed path passing through several branches and nodes of an electrical circuit.
A circuit is called independent if it includes at least one branch that does not belong to neighboring circuits.
Two-terminal network called a part of an electrical circuit with two dedicated terminals - poles. A two-terminal network is designated by a rectangle with the indices “A” or “P”. The index “A” is used to designate an active two-terminal network, which contains sources of E.M.F. The index “P” is used to designate a passive two-terminal network.
Calculation and analysis of electrical circuits is carried out using Ohm's law, Kirchhoff's first and second laws. Based on these laws, a relationship is established between the values of currents, voltages, EMF of the entire electrical circuit and its individual sections and the parameters of the elements that make up this circuit.
Ohm's law for a circuit section
The relationship between current I, voltage UR and resistance R of section ab of the electrical circuit (Fig. 1) is expressed by Ohm’s law
In this case, U R = RI is called the voltage or voltage drop across resistor R, and I is called the current in resistor R.
When calculating electrical circuits, it is sometimes more convenient to use not the resistance R, but the inverse value of the resistance, i.e. electrical conductivity:
In this case, Ohm’s law for a section of the circuit will be written as:
Ohm's law for a complete circuit
This law determines the relationship between the emf E of a power source with internal resistance r 0 (Fig. 1), the current I of the electrical circuit and the total equivalent resistance R E = r 0 + R of the entire circuit:
I = E/R e = E/(r 0 +R)
A complex electrical circuit, as a rule, contains several branches, which can include their own power sources, and its operating mode cannot be described only by Ohm's law. In this case use Kirchhoff's laws , which are a consequence of the law of conservation of energy.
Kirchhoff's first law
The algebraic sum of currents converging at any node is equal to zero.
When writing equations according to Kirchhoff’s first law, currents directed to a node are taken with a “plus” sign, and currents directed from the node are taken with a “minus” sign.
I1-I2+I3-I4+I5=0
Number of equations that can be formed based on first law, equal to the number of nodes in the chain, and only (U – 1) equations are independent from each other. U– number of circuit nodes.
Kirchhoff's second law
Algebraic sum of voltage drops across separate areas of a closed loop, arbitrarily selected in a complex branched circuit, is equal to the algebraic sum of the emf in this loop.
When writing equations according to Kirchhoff’s second law, you must:
1) set conditional positive directions of EMF, currents and voltages;
2) select the direction of traversal of the contour for which the equation is written;
3) write down the equation, and the terms included in the equation are taken with a “plus” sign if their conditional positive directions coincide with the circuit bypass, and with a “minus” sign if they are opposite.
E1 – E2 + E3 = I1R1 – I2R2 + I3R3 – I4R4
The number of independent equations according to Kirchhoff’s second law is:
Methods for analyzing linear DC electrical circuits
Real electrical devices and systems have complex circuits. Specialists are faced with the task of calculating their parameters. The process of calculating parameters in the theory of electrical engineering is usually called “circuit analysis”. Electrical circuits of any complexity obey Ohm's and Kirchhoff's laws. However, applying these laws alone often leads to unnecessarily complex decisions. Therefore, a number of analysis methods have been developed that are adapted to the topology of electrical circuits and simplify the process of calculating their parameters.
Analysis of electrical circuits using Kirchhoff's laws
When analyzing electrical circuits, the value of currents in their branches, the voltage drop across the elements or power consumption are determined by a given E.M.F. value, as well as the values of resistance, conductivity or other parameters by given values current or voltage.
The essence of analyzing electrical circuits using Kirchhoff's laws is to compile a system of independent linear equations.
According to the first Kirchhoff law, (U - 1) equations are compiled, according to the second law B - (U-1) equations.
Analysis of electrical circuits by the method of equivalent transformations
When the electrical circuit includes only one source of E.M.F., its current is determined by the total resistance of the passive receivers of electrical energy. This resistance is called equivalent - Req. Obviously, if Req is known, then the circuit can be represented as two series-connected elements - a source of E.M.F. and Req, and determining the source current comes down to applying Ohm’s law. The process of transition from an electrical circuit with an arbitrary topology to a circuit with Req is called an equivalent transformation. This transformation forms the basis of the analysis method under consideration.
Techniques for converting an electrical circuit are determined by the methods of connecting passive elements. There are different connection methods: serial, parallel, mixed circuit, triangle and star. Let us consider the essence of equivalent transformations for each of the named methods.
Electric circuit with series connection of elements
A series connection is a connection of circuit elements in which the same current I occurs in all elements included in the circuit (Fig. 2).
Based on Kirchhoff's second law total voltage U of the entire circuit is equal to the sum of the voltages in individual sections:
U = U 1 + U 2 + U 3 or IR eq = IR 1 + IR 2 + IR 3,
whence follows
R eq = R 1 + R 2 + R 3.
Thus, when connecting circuit elements in series, the total equivalent resistance of the circuit is equal to the arithmetic sum of the resistances individual areas. Consequently, a circuit with any number of series-connected resistances can be replaced by a simple circuit with one equivalent resistance R eq (Fig. 3.). After this, the calculation of the circuit is reduced to determining the current I of the entire circuit according to Ohm’s law
and using the above formulas, calculate the voltage drop U 1 , U 2 , U 3 in the corresponding sections of the electrical circuit (Fig. 2.).
The disadvantage of sequential connection of elements is that if at least one element fails, the operation of all other elements of the circuit stops.
Electric circuit with parallel connection of elements
A parallel connection is a connection in which all consumers of electrical energy included in the circuit are under the same voltage (Fig. 4).
In this case, they are connected to two nodes of the chain a and b, and based on Kirchhoff’s first law we can write that total current I of the entire circuit is equal to the algebraic sum of the currents of the individual branches:
I = I 1 + I 2 + I 3, i.e.
whence it follows that
From this relationship it follows that the equivalent conductivity of the circuit is equal to the arithmetic sum of the conductivities of the individual branches:
g eq = g 1 + g 2 + g 3.
As the number of parallel-connected consumers increases, the conductivity of the circuit g eq increases, and vice versa, total resistance R eq decreases.
Voltages in an electrical circuit with resistances connected in parallel (Fig. 4)
U = IR eq = I 1 R 1 = I 2 R 2 = I 3 R 3.
It follows that
those. The current in the circuit is distributed between parallel branches in inverse proportion to their resistance.
According to a parallel-connected circuit, consumers of any power, designed for the same voltage, operate in nominal mode. Moreover, turning on or off one or more consumers does not affect the operation of the others. Therefore, this circuit is the main circuit for connecting consumers to a source of electrical energy.
Electric circuit with mixed compound elements
A mixed connection is a connection in which the circuit contains groups of parallel and series-connected resistances.
For the circuit shown in Fig. 5, the calculation of equivalent resistance starts from the end of the circuit. To simplify the calculations, we assume that all resistances in this circuit are the same: R 1 =R 2 =R 3 =R 4 =R 5 =R. Resistances R 4 and R 5 are connected in parallel, then the resistance of the circuit section cd is equal to:
In this case, the original circuit (Fig. 5) can be represented as follows (Fig. 6):
In the diagram (Fig. 6), resistance R 3 and R cd are connected in series, and then the resistance of the circuit section ad is equal to:
Then the diagram (Fig. 6) can be presented in an abbreviated version (Fig. 7):
In the diagram (Fig. 7), the resistance R 2 and R ad are connected in parallel, then the resistance of the circuit section ab is equal to
The circuit (Fig. 7) can be represented in a simplified version (Fig. 8), where resistances R 1 and R ab are connected in series.
Then the equivalent resistance of the original circuit (Fig. 5) will be equal to:
|
Rice. Rice. 8 |
Rice. Rice. 9 |
As a result of the transformations, the original circuit (Fig. 5) is presented in the form of a circuit (Fig. 9) with one resistance R eq. Calculation of currents and voltages for all elements of the circuit can be made according to Ohm's and Kirchhoff's laws.
The essence of the equivalent transformation method:
1. Sections of the electrical circuit with elements connected in series and parallel are replaced with one equivalent element. Through sequential transformations, the circuit is simplified to an elementary form.
2.Using Ohm's law, the current of a simplified circuit is found. Its value determines the current of the branch closest to the E.M.F. source. (current of the first branch). This makes it easy to calculate the currents of the remaining branches.
Instantaneous value;
Amplitude value;
Initial phase;
Effective value;
Average value;
Complex of effective or amplitude value, etc.
Instantaneous value
Instantaneous value of quantity a is written as:
a = Am sin (ωt +ψ),
where Am is the amplitude (maximum value) of the quantity;
t – current time value, s;
ψ – initial phase.
We write the instantaneous values of current i, voltage u or EMF in the form:
i=Im sin (ωt+ψi),
u=Um sin (ωt+ψu),
e=Em sin (ωt+ψe).
The sine argument (ωt +ψ) is called phase. The angle ψ is equal to the phase at the initial time t =0 and is therefore called initial phase.
Angular frequency ω is related to period T and frequency f =1/T by the formulas:
.The effective value of a sinusoidal current is often called the root mean square or effective value.
The effective values of currents and voltages are shown by most electrical measuring instruments (ammeters, voltmeters).
The current values indicate the rated currents and voltages in the passports of various electrical appliances and devices.
Under average value sinusoidal current is understood as its average value over half a period:
Likewise:
Elements of electrical circuits of sinusoidal current
Basic elements of electrical circuits of sinusoidal current:
Sources of electrical energy (and current sources);
Resistive elements (resistors, rheostats, heating elements etc.);
Capacitive elements (capacitors);
Inductive elements (inductors).
Resistive element
According to Ohm's law, the voltage on the resistive element is: u=i⋅R=R⋅Im sinωt=Um sinωt, where Um =R⋅Im and current i=Im sinωt.
This implies:
1. Current and voltage in a resistive element are in phase (change in phase).
2. Ohm's law holds true for both amplitude values of current and voltage: Um =R⋅Im, and for effective values of current and voltage: U=R⋅I.
Let us express the instantaneous power p in terms of the instantaneous values of current i and voltage u:
p=u i =Um Im sinωt sinωt =U I (1−cos2ω).
Inductive element
A classic example of an inductive element is an inductor - a wire wound around an insulating frame.
uL = ω⋅L⋅Im cosωt = Um sin(ωt+900),
where Um = ω⋅L⋅Im = XL⋅Im.
The quantity XL =ω⋅L is called inductive reactance , is measured in ohms and depends on the frequency ω.
An important conclusion follows from these expressions:
1.The current in the inductive element is out of phase with the voltage by(900).
2. An inductive element provides resistance to a sinusoidal (alternating) current, the modulus of which X L = ω ⋅ L is directly proportional to the frequency.
3.Ohm's law is satisfied both for the amplitude values of current and voltage: Um =XL⋅Im, and for effective values: U=XL⋅I.
Instant Power:
p = u⋅i = Um cosωt⋅Im sinωt = U⋅I sin2ωt.
The instantaneous power on the inductive element has only a variable component U⋅I sin2ωt, changing with double frequency (2ω).
The power periodically changes sign: sometimes positive, sometimes negative. This means that during some quarter periods, when p>0, energy is stored in the inductive element (in the form of magnetic field energy), and during other quarter periods, when p
IN this section provided for your attention Books on electronics and electrical engineering. Electronics is the science that studies the interaction of electrons with electromagnetic fields and the development of methods for creating electronic devices, devices or elements used mainly for transmitting, processing and storing information.
Electronics is a rapidly developing branch of science and technology. She studies the physics and practical use various electronic devices. Physical electronics include: electronic and ionic processes in gases and conductors. At the interface between vacuum and gas, solid and liquid bodies. Technical electronics includes the study of the design of electronic devices and their application. The field dedicated to the use of electronic devices in industry is called Industrial Electronics.
On the site you can download a large number of books on electronics for free. In the book "Circuit Engineering" electronic means» the elemental base of electronic devices is considered. The basic principles of constructing analog, pulse and digital devices. Particular attention is paid to storage devices and information converters. Microprocessor systems and devices are discussed in a separate section. For students of higher education institutions. Also download books by the authors: Levinshtein M.E., Simin G.S., Maksina E.L., Kuzmina O., Shchedrin A.I., Leontyev B.K., Shelestov I.P., Piz R., Rodin A., Bessonov V.V., Stolovykh A.M., Drigalkin V.V., Mandl M., Lebedev A.I., Braga N., Hamakawa Y., Revich Yu.V., Abraitis B.B. ., Altshuller G.B., Elfimov N.N., Shakulin V.G., Baida N.P., Byers T., Balyan R.H., Obrusnik V.P., Bamdas A.M., Savinovsky Yu A.A., Bas A.A., Bezborodov Yu.M., Bocharov L.N., Bukhman D.R., Krotchenkov A.G., Oblasov P.S., Bystrov Yu.A., Vasilevsky D.P. ., Vasiliev V.A., Vdovin S.S., Veresov G.P., Yakubovsky S.V., Shakhgildyan V.V., Chistyakov N., Horowitz P., Hill W., Phelps R., Sidorov I N., Skornyakov S.V., Grishin G.G., Moshkov A.A., Olshansky O.V., Ovechkin Yu.A., Vikulin I.M., Voishvillo G.V., Volodin A.A. ., Galperin M.P., Kuznetsov V.Ya., Maslenikov Yu.A., Gausi M., Lacker K., Elyashkevich S., Gendin G.S., Golovkov A.V..
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The course of lectures on electronics corresponds to the programs of the disciplines “Electronics”, “Electrical engineering and fundamentals of electronics”, “Electronic engineering”, “Power supply of electronic devices”. The author taught the proposed course for a number of years at the St. Petersburg State Institute of Precision Mechanics and Optics ( Technical University). The course consists of 35 lectures and is designed to study the discipline over one or two semesters.
The lectures contain carefully selected illustrations that can be used as visual aids, as well as reference tables that give the characteristics of the most advanced modern electronic components and devices.
Electrovacuum devices.
Thermionic emission. Electron emission is the process of a body emitting electrons into the space surrounding it. To ensure that electrons leave the body, they need to provide additional energy. In this regard, we are considering the following types electron emission: thermionic, electrostatic, photoelectronic and secondary.
With thermionic emission, additional energy is imparted to the electrons by heating the body. Electrostatic emission occurs due to the high electric field strength at the surface of the body. With photoelectron emission, the surface of the body is illuminated. Secondary emission appears as a result of the impact of the electron flow of primary emission on the surface of the body. When primary electrons bombard the surface of a body, secondary electrons are knocked out of it; this process is called secondary emission.
CONTENT
Preface
Section 1. Elements of electronic equipment
Lecture 1. Electrovacuum devices
Lecture 2. Semiconductor diodes
Lecture 3. Special types of semiconductor diodes
Lecture 4. Bipolar transistors
Lecture 5. Unipolar transistors
Lecture 6. Power semiconductor devices
Lecture 7. Limit operating modes of transistors
Section 2. Analog integrated circuits
Lecture 8. Operational amplifiers
Lecture 9. Analog voltage comparators
Lecture 10. Analog voltage multipliers
Lecture 11. Switches analog signals
Section 3. Digital integrated circuits
Lecture 12. Digital logic elements
Lecture 13. Triggers
Lecture 14. Pulse counters and registers
Lecture 15. Code converters, encryptors and decryptors
Lecture 16. Multiplexers and demultiplexers
Lecture 17. Digital storage devices
Section 4. Linear Electronic Devices
Lecture 18. Electronic amplifiers
Lecture 19. Limiting sensitivity and noise of electronic amplifiers
Lecture 20. Active filters
Lecture 21. Active resistance converters
Lecture 22. Differentiating and integrating devices
Section 5. Nonlinear electronic devices
Lecture 23. Electrical signal generators
Lecture 24. Electrical signal modulators
Lecture 25. Demodulators of electrical signals
Section 6. Analog-to-digital functional devices
Lecture 26. Analog-to-digital converters
Lecture 27. Digital-to-analog converters
Lecture 28. Analog signal sampling and storage devices
Section 7. Power supplies for electronic devices
Lecture 29. Principles of constructing secondary power supplies
Lecture 30. Power supply rectifiers
Lecture 31. Voltage stabilizers
Lecture 32. Switching power supplies
Lecture 33. Integrated circuits for controlling switching power supplies
Lecture 34. Electronic power factor correctors
Lecture 35. Computer modelling electronic devices
Add-ons
Lecture 1d. Physical Basics semiconductor electronics
Lecture 2d. Phase-locked loop devices
List symbols
List of abbreviations
Recommended reading.
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Sections: I – steep, II – flat, III – thermal breakdown area.
The main one is the II (reinforcing) section. On it, the transistor can be represented as a controlled current source.
Slope of the flat section: at?U CE => ?? 0 => ? volume charge => ? double layer width => ? effective base width => ? probability of recombination => ? I K.
, 
, 
To increase I B you need to increase U BE:
I-section 
, 
Let us reduce U CE at U BE = const, when U CE = U BE = U CE US, with a further decrease in U CE, U CB will change sign - the collector junction is under direct voltage.
Diffusion of holes occurs from the collector to the base, therefore the current I K decreases, the transistor loses its amplifying properties.
Section I is used in the switching mode of the transistor. U KEN? 0.2 h 1 V
III section – thermal breakdown section. If U CE increases, the electric field energy becomes sufficient for impact ionization, the non-working section.
Input characteristic
Family of curves I B = f(U BE) with U FE = const
I B = I K + I E
The input characteristic is the current-voltage characteristics of two parallel-connected p-n junctions.
When U CE = 0 on EB and BC U DIRECT.
When U KE > U KEN on EB – U DIRECT, on BC – U REVERSE.
When U BE = 0 I B = I KBO
I B = I K - I E = (1-?) H I E - I KBO from (2)
- base resistance – input dipole resistance of the transistor
Transistor amplifiers
Devices which, by changing a low power signal, control the change high power on load
DC amplifiers.
AC amplifiers.
The DC amplifier of an alternating signal should not perceive the DC component; for this purpose, a capacitor is placed at the input. The influence of the capacitor eliminates the zero drift.
An AC amplifier is simpler than a DC amplifier because... the amplifier must perceive a constant component, so you cannot install a capacitor and deal with zero drift in other ways that lead to the complication of the amplifier circuit.
Common emitter amplifier stage
Let's build transfer characteristic cascade.
Class B mode
Section I:
I B? 0, transistor is closed, I B = I KBO, I K =? H I B = 0, U KE =E K - I K H R K, because I K =0,
Section II:
I B has a value (from the input characteristic) that is not equal to zero. I K = ? W I B? 0 with an increase in U BE, I B, I K increase and U KE decreases.
III Section
With increasing U BE; U KE remains constant and is equal to U KE = (0.2h1) V
Measuring limit:
I KBO? I K? 
; U KEN? (U KE = U OUT) ?E K
The signs of ∆U IN and ∆U OUT are different; such a cascade is called inverting.
Lecture 7
Class B mode
The output voltage does not change.
Disadvantage: loss of information in the second half-cycle.
To achieve a constant positive signal, it is necessary to bias the input signal (bias emf).
Class A mode
With alternating current, the constant component is removed by a capacitor connected in series; with direct current, the constant component U OUT is removed by turning on the back EMF at the output.
Key Mode
A mode with a large amplitude of the input signal, in which all three sections of the characteristic are captured. The second signal on the curve is formed at the minimum level.
The output voltage shape is distorted, i.e. amplitude limitation occurred. The higher the voltage gain, the more similar the output signal is to a square wave.
It is used in pulse technology, where it is not the signal amplitude that is important, but the mutual phase shift between U IN and U OUT.
Power released in transistors
Heats up the pn junction and can lead to thermal breakdown. To reduce power you need to work in key mode.
Rest mode
Introduced as a method for calculation and analysis electronic circuits. To create a rest mode, all EMFs are turned on constant (E K, E SM, E COMP)
E COMP is turned on to eliminate the DC component U OUT in class A.
1) Let U ВХ = 0, because there is E SM, so the transistor is open, currents I BP, I CP, I EP flow? 0, U KEP? 0, E COMP = U CEP. When the power supplies are turned on, quiescent currents flow in the circuit and there is a U CEC so that output voltage was not equal to zero, you must enter U COMP = U CEP.
Disadvantage: dependence of the transistor current and voltage on temperature.
When the temperature rises by 10° C, the current I of the OCB increases by 2 times. Also, when the temperature changes, the current caused by the main carriers changes: when the temperature changes by 20-30 ° C, I K increases by tens of percent, because recombination centers (crystal lattice defects) are filled, so their number and the probability of recombination decrease and? increases.
With increasing temperature, when I BP = const, I CP increases, because
I CP = ? Ch I BP, U CEP decreases, because U KEP = E K - I KP H R K, so U OUT will not be constant. To eliminate this effect, compensation schemes using feedback are used.
Feedbacks
Transferring the output signal to the input of the device. If the currents add up, the connection is parallel; if the voltages are added, the connection is serial. If the signs of the added signals are the same - positive feedback (POF), if the signs are different - negative feedback (NF). PIC is used to speed up the food point, i.e. to increase the performance of the device, but is more unstable. The use of OOS increases the stability of the device; it is introduced by inclusion in the emitter circuit.
Let's write the equation according to Kirchhoff's second law for the input circuit:
U VX + E SM = U BE + I E CH R E
U BE = U VX + E SM - I E H R E? U VX + E CM - I K CH R E
I E? I K, because ? = 0.99 h 0.9
That is, R E reduces the OOS in terms of current.
Advantage: with increasing temperature and I BP = const => ? ? => ? I KP => ? I K H R E => ? U BE => ? I B => ? I K, thus I K and therefore U KE remain constant.
Disadvantage: U OUT decreases due to a decrease in U BE, therefore the gain K U decreases,
I EP CH R E? 0.1 H E K – criterion for choosing R E. This R E provides sufficient temperature stabilization and a slight decrease in U OUT.
Basic parameters of a cascade with a common emitter
R IN, R OUT, K EX. .
Assumptions: we consider only the variable components (increment) i, u. Internal resistance of sources constant emf for alternating current it will be zero.
, ∆i? 0, ∆u = 0, because E K constantly. Thus, R K is connected to the ground at its upper end, because
R VN = 0, 
U VХ = ∆I B H r B + ∆I E H R E
- dynamic input resistance of the transistor r B =h 11EKV.
∆I E = ∆I B + ∆I K = ∆I B + ? Ch ∆I B = ∆I B Ch (1+?)
U VX = ∆I B H
R VX? 1000 OM (which is relatively small for an ideal R VX =?)
Lecture 8
2) K U ХХ – gain in idle mode.
neglect r B,
r B + (? + 1) CH R E? (? + 1) H R E; 
?K UXX
When the voltage is turned on, I N will be added to I K, so the gain will decrease (K U RAB
3) To output ROUT we use the equivalent generator theorem, the EMF is short-circuited, the load is replaced with an ohmmeter.
U OUT = 0, therefore I B = 0; I K and I E = 0; R OUT = R K? 1000 ohm
Disadvantages: in terms of input and output resistances, a cascade with a common emitter has unsatisfactory parameters (?/0 in the ideal case).
Methods for constructing a DC amplifier (DC amplifier)
3 power supplies are replaced by one. R 1 and R 2 create a displacement emf; R 3 and R 4 – compensation EMF.
Disadvantages: the input signal source and output voltage do not have a common point, i.e. It is inconvenient to use such a scheme. To eliminate this drawback, it is necessary to use a bipolar power source.
R 1 and R 2 creates U COMP. Because point 0 at U VX has? 1 = 0, and t. –E K? 2 = - E K, then
1 > ? 2, i.e. an EMF source is implicitly introduced into the circuit (into the input circuit).
AC amplifier
C 1 and C 2 cut off the DC component in U IN and U OUT respectively. C 1 high pass filter at the same time.
Cascade with common collector (emitter follower)
Purpose: used as a matching stage between an amplifier stage with a common emitter and a low-power voltage source U VX, as well as with a high load.
If there were no OK: R VHOE is relatively small, and R VHOE is relatively large, so I H is large => ? U IN (U IN? voltage at the output resistance; U OUT R IN, R OUT? R G H I IN =>
Disadvantages: the cascade with OK does not increase the voltage, K UXX ? 1 (0.9h0.99) U OUT = U IN - U BE, U BE > 0? 0.5 h 0.7 V.
The scheme is called OK, because the common point is ground, and E K is grounded, the second name is emitter follower, and is non-inverting.
Let ∆U VX increase; This means that ∆I B, ∆I E, ∆I E R E increases.
Cascade parameters with OK
? 10 4 ohm
2) 
, R Н = ?
U IN = ∆I B CH , U OUT = ∆I E CH R E = ∆I B CH (1 + ?) CH R E
Lecture 9
3) R OUT cascade with OK
because e G = 0 => ∆I B = 0, => ∆I E = 0; ROUT = R E.
Task:
K – closed – OK
K – open – OE
R K = 2000 OM
E CM = 0.4 V
~U VХ M = 1 V
Determine 3 main parameters for a circuit with OK and OE.
R IN, R OUT, K UXX for OE and OK, draw oscillograms of U IN, U OUT1, U OUT2.
1. Cascade with OE (K - open)
R VX = r B + (? + 1) R E = 100 + (100 + 1) 400 = 40.5 kOhm,
R VX = 40.4 kOhm at r B = 0
R OUT = R K = 2000 ohm
E CM K UXX = 0.4 5 = 2 V
U VХМ K UXX = 1 5 = 5 V
2. Cascade with OK
R IN = r B + (? + 1) (R E ||R N) = 100 + (100 + 1) 400 = 40.5 kOhm
ROUT = R E = 400 OM
Oscillograms U IN, U OUT1, U OUT2.
Zero drift
Zero drift is a characteristic feature of the UPT. Zero drift means a change in U OUT at a constant U IN. Reasons: instability of the power source, temperature influence, changes in the parameters of the power point of the devices over time (due to aging).
1) Instability of the power supply.
Let E K increase => ?E CM => ?I B => ?I K => ?U RK => U OUT will decrease, because K U > 1, which means the change in U OUT will be greater than the change in E K .
2) Temperature change.
As the temperature rises, does it increase? => ?I K => ?U RK, and U OUT decreases.
U OTHER OUTPUT MAX – maximum U OUT zero drift.
It should be U IN >> U DR.IN. MAX ; otherwise, we will not be able to distinguish the zero drift from the useful signal at the output. An effective remedy combating zero drift - the use of amplifier stages based on balanced bridges.
Differential cascade (DC)
4 arms are formed by R K 1, R K 2, VT1, VT2. The first diagonal is the supply E K, -E K. The second diagonal is the loads R K 1, R H. DC amplifies the difference in input signals. It has good characteristics provided that its elements are identical, i.e. R K 1 = R K 2 , VT1 = VT2, which is achieved when executed on a single chip based on a microcircuit.
Rest mode
Turn on E K 1 and –E K2; U VX1 = U VX2 = 0, U BEP1 = U BEP2 > 0, U BE = - U EP.
U EP = [- E K1 + (I EP1 + I EP2) R E ] ? 0
those. U BE = E SM = - U EP, therefore I BP1 = I BP2 flow;
U KEP1 = U KEP2 = E K 1 – I KP1 R K 1 – U EP = E K 1 – I KP2 R K2 - U EP
U OUT = U KEP2 – U KEP1 = 0
Let the temperature increase, therefore? ? => ?I CP1 = I CP2 => ?I EP1 = I EP2 => ?U EP => ?U BEP1, U BEP2 => ?I BP1, I BP2 => ?I CP1, I CP2 => ? I EP1, I EP2, i.e. I EP1 + I EP2 = const, because R E is large, so stabilization is good. If a direct current flows through R E, therefore R E can be replaced by a current source with R VNUT = ?.
Lecture 10
∆U E – feedback signal stabilizing the sum I E1 + I E2 = const
Zero drift
Let E 1 increase => ?U KE1 = U KE2, U OUT = U KE2 – U KE1 = 0
Any symmetrical changing signals in the circuit do not lead to zero drift.
Let's apply an alternating 2nd signal.
1) Between the bases of the transistors.
Let 
will be positive, which means
∆U BE1 > 0 => ∆I B1 > 0 => ∆I K1 > 0 => ∆I E1 > 0 => ∆U KE1 
will be negative, which means
∆U BE2 = 0 => ∆I B2 ∆I K2 = 0 => ∆I E2 ∆U KE2 > 0.
U OUT = ∆U CE2 - ∆U CE1 = 2 ∆U CE
If U ВХ1 = -U ВХ2, therefore ∆I E1 = -∆I E2
because the first current increases, and the second decreases, which means I E1 + I E2 = const
This means ∆U E = 0, therefore:
A) Feedback does not affect the gain of the differential stage.
B) In a differential cascade, the contradiction between the need to stabilize the mode due to feedback and the influence of R E on the gain of the cascade is overcome.
2) Now we apply the input signal to the base of the first transistor, while short-circuiting the second input. U ВХ1 = e > 0; U ВХ2 = 0.
This means ∆U BE1 > 0 =>∆I B1 > 0 => ∆I K1 > 0 => ∆I E1 > 0 => ∆U KE1
With an increase in I B1, => ?I E1, because I E1 + I E2 = const; I E2 decreases and
∆I E2 = -∆I E1.
, ∆I B2 = -∆I B1, ∆I K 2 = -∆I K 1, ∆U KE2 = -∆U KE1,
U OUT = ∆U KE2 - ∆U KE1 > 0
Conclusion: input 1 is non-inverting, because ∆U IN >0 and ∆U OUT >0. This means that from similar transformations, input 2 is inverting. When an input signal is applied to one transistor, the currents and voltages in both transistors will change.
The differential cascade amplifies the difference in input voltages when U IN1 = U IN2, therefore U OUT = (U IN1 – U IN2) K U = 0 The amplifier operates in the common-mode mode. Due to some dissimilarity of parameters: U OUT = k C U IN, where k C is the common-mode signal transmission ratio. The smaller k C, the better quality amplifier.
Disadvantages: lack of a common point between the input and output signals. To eliminate this, an asymmetric differential cascade (DC) circuit is adopted.
The common point is the earth.
Main parameters of the recreation center
U OUT = 2 H ∆U CE, because I E1 + I E2 = const, which means the current source R E =?
, hence 
;
1)
2) Cascade input impedance
; R BX = 2 H r B,
FEDERAL AGENCY FOR EDUCATION OF THE RF
FGOU SPO PROKOPYEVSKY
INDUSTRIAL AND ECONOMIC TECHNIQUE
LECTURE NOTES
BY DISCIPLINE
"ELECTRONIC EQUIPMENT"
SPECIALTIES
"AUTOMATION OF TECHNOLOGICAL PROCESSES AND PRODUCTION"
Compiled by: Vasiliev D.Yu.
PROKOPIEVSK 2011
Lecture 2. Semiconductor materials. Physical processes. Enable p-n transition. Basic parameters of diodes. 9
Lecture 3 Modes work p-n transition. Basic parameters of diodes. 12
Lecture 4 Types of diodes: zener diodes, stabilizer, Schottky diode, varicap, tunnel diode, reverse diode. 15
Lecture 5 Classification and notation system 17
Lecture 6 Bipolar transistors. Notation. 20
Lecture 7 Options for switching on bipolar transistors. Main characteristics. 22
Lecture 8 Field-effect transistors. Device, types, designations. 24
Lecture 9 Field-effect transistor With manager p-n transition, operating modes, current-voltage characteristics. 29
Lecture 10 Types of MOS transistors. Switching schemes. Application. 32
Lecture 11 Thyristors. Types. Device. 40
Lecture 12 Characteristics of thyristors 45
Lecture 13 Optoelectronic devices. General characteristics. Emitting diode. 47
Lecture 14 Photoresistor, photodiode. 49
Lecture 15 Information display devices: PPI, VLI, GRI 50
Lecture 16 Liquid crystal indicators. Principle of operation. 51
Lecture 17 Test. LCD types. 52
4th semester. 54
Lecture 18 Rectifier design 54
Lecture 19 Basic design relationships. Ways to reduce ripple factor 55
Lecture 20 Inverters 56
Lecture 21 Capacitive smoothing filters for rectifiers 57
Lecture 22 Inductive smoothing filters for rectifiers 58
Lecture 23 Parametric voltage and current stabilizers. Compensation and pulse stabilizers voltage and current 59
Lecture 24 Types of signals and their characteristics 60
Lecture 25 Amplifier devices. Classification of amplifiers. 61
Lecture 26 Basic characteristics of amplifiers (Amplitude, frequency response, phase response, transition) 62
Lecture 27 Feedback in amplifiers. Classification feedback. 63
Lecture 28 Amplifiers bipolar transistors. Power amplifiers 64
Lecture 29 Operational amplifiers. 65
Lecture 30 Filters. 66
Lecture 31 Generators. Types of generators. 67
Lecture 32 Pulse generators. Multivibrator. Single vibrator. Blocking generator. 68
Lecture 33 Test. Integrated circuits. 69
Lecture 34 Implementation of basic logical functions 70
Lecture 35 Classification and main parameters of digital ICs 71
Test lesson. 72
Lecture 1 Introductory lesson. Physical quantities.
Educational purpose:
Students’ assimilation of knowledge on the topic of the lesson.
Developmental goal:
Development of analytical, synthesizing and abstract thinking, skills to apply knowledge in practice.
Development of academic skills, initiative, self-confidence.
Development of skills to act independently.
The purpose is educational
Strive to cultivate a sense of neatness.
Contribute to instilling a sense of pride in your chosen profession.
Ability to manage emotions and treat each other with care.
Lesson type: Lesson on learning new material and initial consolidation
Organizing time:
Checking the condition of the audience, the appearance of students,
Availability of badges, educational supplies: pens, notebooks.
Presence of students in class.
Survey or testing.
Issue of new material:
Characteristic academic discipline and its connection with other disciplines of the curriculum, its role in the development of science, engineering and technology.
Objectives of the course being studied and its place in the overall system of training mid-level specialists;
the role of discipline in the development of science, technology and technology
Brief overview and main directions of development and application of industrial electronics.
Reliability of electronic devices.
Paths and implications of microminiaturization of electronic devices and devices.
The concept of electromagnetic compatibility of electronic devices
Consolidation.
Homework.
Lesson summary (Reflection). Checking the progress of the work. Grading.
What is electronics? - This is the transmission, reception, processing and storage of information using electrical charges. This is science, technology, industry.
As for information, always when there was humanity, this was all there. Human thinking, Speaking, keepsake bundles, signal fires, semaphore telegraph, etc. - is the reception, transmission, processing and storage of information. And this was no less than 5000 years. But only recently, at the end of the 18th century, were the telephone and telegraph invented - devices for transmitting and receiving information using electrical signals. This is the beginning of electronics, as it is now called.
Then electronics develops quite quickly. In 1895, Popov invented and built a working radio model - electronic device for wireless information transmission - lightning detector. Hertz conducted experiments on the propagation of radio waves, Marconi developed and applied these experiments to build a radio with the choice of a transmitting radio station according to the wavelength of the radiation.
But in the beginning there was no good amplification element for electrical devices. Therefore, the real development of electronics began in 1904, when the radio tube was invented - the diode, and in 1907 - the triode. They look like shown in Fig. On the left is a radio tube - a diode, which consists of a sealed cylinder, and inside the cylinder there is a vacuum and several metal structures with electrodes brought out. One of them is a filament; an electric current is passed through it, which heats it to a temperature of 700-2300 o C. This filament heats up the cathode, to which a negative voltage is applied, and the cathode emits electrons. A positive voltage is applied to the anode, the potential difference is quite high (100-300 V), and therefore the electrons emitted from the cathode will fly to the anode, and therefore current will flow in the lamp. When the sign of the voltage changes, electrons will not fly out of the cold anode, and there will be no current. Therefore, the diode can act as an AC voltage rectifier.
On the right fig. a radio tube is shown - a triode. It has everything the same as a diode, but there is an additional electrode - a control grid. Typically, a negative potential is applied to the grid, and it repels electrons emitted from the cathode. Therefore, the more negative the grid potential, the fewer electrons will flow from the cathode to the anode. Thus, the grid potential serves to control the current in the radio tube. Typically, the grid in the lamp is located much closer to the cathode than the anode, so low grid potentials can control large lamp currents. If voltage is applied to the anode through a large resistance, then the potentials on the anode will change more than on the grid. This is a good electronic voltage amplifier.
Radio tubes have come a very long way in development. More advanced tetrodes and pentodes appeared - lamps with four and five electrodes with high gain factors. They began to make more complex radio tubes: with more than five electrodes. Of these, the most widely used are dual radio tubes: dual diodes, triodes, diode-triodes, etc. Gas-filled lamps appeared - gastrons. They contain gas, although it is under slight pressure. Usually it is ionized, ions appear - atoms without an electron, i.e. having a positive charge.
The flow of current in such lamps is more complex: it can be either electronic or ionic. The sizes of radio tubes were very different: from miniature finger lamps to huge ones as tall as a person.
The invention of the triode opened up great opportunities for the development of electronics. By the Second World War, the worldwide number of radio tubes produced had grown to many millions of units per year. Many devices for receiving and transmitting information were invented and created. Telephone and telegraph, radio receivers and radio transmitters. Instead of gramophones, record players appeared and tape recorders appeared. Televisions began to be developed.
But this is all only part of the tasks of electronics - receiving, transmitting and storing information. Where is information processing, the most important, complex and interesting part of it? Obviously, it can only be done computing device.
By the beginning of World War II, electronic adding machines had already appeared - digital information processors. But the real development of this field of electronics began with the emergence of electronic computers(COMPUTER). It began in 1948 - the first computer using radio tubes was made in the USA - ENIAC. Here are some of its parameters:
As can be seen from this table, this is a grandiose structure. And it had everyone characteristic features modern computer: memory that contained data and a program for processing it, an arithmetic-logical device, communication with external devices. But, of course, she also had many shortcomings. Compared to the current state of the art, this computer is less complex than a simple calculator, especially if it can be programmed. But in terms of weight (30 tons compared to 50 g), in terms of space occupied, and in terms of power dissipation, modern calculators are significantly superior to it. It is especially important that their speed is no less than 1 MHz, i.e. one hundred times more than the first computer.
But much more significant is the service life of the first computer. It was mainly determined by the service life of the radio tube. And it is determined by the failure rate
= 10 -5 h -1
Those. Out of 100,000 radio tubes, one will fail within 1 hour. Or in other words, the service life of one radio tube is equal to
T = 1/ = 10 5 h
But when, instead of 5-20 radio tubes, 18,000 radio tubes must operate simultaneously, the situation changes dramatically. All radio tubes last 12 years, but fail randomly at any time. And the failure of even one radio tube leads to the failure of the entire device. In this case, for the entire device you can write:
total = N * = 18,000 * 10 -5 = 0.18 h -1
And the service life of the entire device is
T total = 5 hours
Those. ENIAC service life is only 5 hours! On average, every 5 hours some radio tube failed. Finding a non-working one out of 18,000 radio tubes is not so easy. And after it is found, it is necessary to replace it and test the computer for operability. All this took about 5 more hours.
But we need to make more complex computers. If we complicate it so that it contains 10 times more radio tubes, the service life will decrease by 10 times, i.e. will be equal to 0.5 hours. And repairs will take even more time. This is a disaster of numbers.
All further development of electronics is associated with the fight against the catastrophe of quantities. To do this, it was necessary to reduce the failure rate of the radio tube. But a radio tube is a complex device. Firstly, there is a deep vacuum inside it; if it is lost, the anode current of the radio tube will decrease due to collisions of electrons with air atoms and with ions resulting from these collisions. The lamp grid is a wire spiral that is wound around the cathode. It is weak and cannot withstand overloads or vibrations. The filament is heated to a high temperature, so it emits not only electrons, but also quite a lot of atoms, i.e. The thread evaporates all the time. It was not possible to eliminate all these shortcomings and increase service life.
And then in 1948 the transistor was invented. It looked like shown in Fig.
It is much better than a radio tube: smaller, lighter, no filament. Its dimensions are no more than one millimeter. This is a single piece of semiconductor, a very durable crystal, not inferior in strength to steel or cast iron. Therefore, the transistor has a lower failure rate, approximately = 10 -7 h -1.
Transistors very quickly conquered the market. Already in 1949, the first transistor computer, similar to ENIAC, was made in the USA - i.e. a year after the invention of the transistor. To illustrate this, here is a quote from the magazine:
"Science and Life", 1986, No. 2, p. 90:
"... if we count from the first machines, then today the volume of internal computer memory has increased hundreds of times, and the speed has increased hundreds of thousands of times, energy consumption has decreased thousands of times, and the cost has decreased. Experts estimate that if progress had progressed at such a pace automotive industry, then a car of the Volga class would move almost at the speed of light, would consume several grams of gasoline per hundred kilometers and would cost a few rubles.”
But that was 15 years ago!
Let's take a closer look at how the transistor was invented? It turns out that it was invented by studying the influence of two pn junctions (semiconductor diodes) on each other, located at a very short distance. (This is shown in the figure.)
Two very sharp metal needles were placed on the surface of germanium (semiconductor) at a short distance
from each other, and then cauterized (a strong current was passed through
A short time). In this case, the semiconductor was heated, the metal partially dissolved in the semiconductor, and also diffused into it. The metal was selected in such a way that its atoms created an electronic semiconductor ( P-type). Thus, two pn transitions were obtained. And since they were very close, they interacted, and a transistor was obtained.
The first transistors were made this way, and this technology was called point technology. Its shortcomings are obvious. The fact is that, according to the theory of transistors, the distance between p-n junctions should be much less than the diffusion length (what this is, we will say in the following lectures), and it is very small, ranging from a few to tens of micrometers (usually they say microns) . It is impossible to place two needles so close - a micron is much smaller than the thickness of a human hair (about 50 microns).
It can be assumed that the distance between the needles is comparable to the thickness of a human hair and is approximately equal to 0.1 mm, or 100 microns. Next, you need to pass an electric discharge spark through the needles so that the melting, dissolution and diffusion of the metal occurs. The process is difficult to reproduce. Therefore, many transistors made using this technology turned out to be defective: either the pn junctions merged, or the distance between them was too large. And the gain of the transistor itself was generally a random variable.
Improvement in transistor manufacturing technology was required. The first step in this direction was
obtained when point technology was replaced by alloy technology (see figure). Shown here is the basic design used in this method: two graphite plates with small aluminum pits surround either side of an electron-conducting (n-type) germanium plate. This design is placed in a high temperature oven (600-800 o C). Aluminum melts and diffuses into germanium. When diffusion has reached a sufficiently large depth, the process is stopped. Aluminum is an acceptor, i.e. where diffusion took place, germanium became a semiconductor with hole electrical conductivity (p-type). It looks like this:
Now you just need to cut the resulting plate into pieces containing three different types electrical conductivity (transistors), place it in the case and solder the crystal to the legs - the transistor is ready.
Alloy transistors are much better than point transistors: more controlled process diffusion, simply maintain a constant temperature in the furnace and regulate the diffusion time. Point technology was replaced by alloy technology.
However, alloy technology has certain disadvantages, the main ones being that diffusion is carried out from different sides. The thickness of the plate cannot be less than 0.5...1 mm, since otherwise it will become flexible, will curl, and the plate cannot be considered flat. This means that the thickness to which diffusion needs to be carried out is at least 250 microns, the thickness of the base is 1...5 microns, and it must be done accurately (with an accuracy of no worse than 1 micron). As a result, it is necessary to make diffusion to a depth of 250 microns with an accuracy of no worse than 1 micron. This is difficult to achieve.
Gradually, during the development of transistor manufacturing technology, we came to diffusion technology, which is based on photolithography.
Let us briefly describe photolithography. Its task is to create a mask for diffusion on the surface of silicon (it is best suited for photolithography), which will then be produced locally. This mask must withstand very high temperatures (1200...1300 0 C). Silicon oxide is suitable for this purpose, which is obtained very simply by oxidizing silicon itself at high temperatures in water vapor and oxygen. Its thickness is on the order of 1 micron, but this is enough to prevent impurity atoms from diffusing into the semiconductor. But in the right places, holes (windows) are made in the silicon dioxide, which will determine where local diffusion will take place.
For the manufacture of windows, photoresist is usually used - it is practically a photoemulsion, which has special properties:
1. It must withstand etching with hydrofluoric acid (ordinary photographic emulsion cannot withstand), which is necessary when etching windows in silicon dioxide.
2. It has high resolution (more than 1000 lines per mm, or less than 1 micron).
3. It has a low viscosity so that it can spread to a layer 1 micron thick (otherwise so high resolution not receive).
4. It is sensitive to light irradiation in the ultraviolet region (light wavelength is 0.3 microns).
Only a special substance can have so many special properties. This is plastic that is destroyed under the influence of light, or, conversely, formed under the influence of light. Many such substances have been found. These are photoresists.
So, in the process of photolithography, we can create a thin layer of silicon dioxide (on silicon, a semiconductor), then apply a very thin layer of photoresist, then through a photomask (a special photographic plate on which there are many pre-calculated and manufactured dark and light places) illuminate it with ultraviolet light, then develop, that is, remove illuminated areas (or vice versa, unlit), then you can remove silicon dioxide through windows in the photoresist (etching in hydrofluoric acid) and remove the photoresist itself, since its residues can interfere with the high-temperature diffusion process.
Now you can diffuse from one side:
This means that it is easier to make a precisely controlled thin base layer: we do diffusion to a depth of approximately 5...6 µm, then a second diffusion at 3..4 µm. The base will be approximately 2 microns. The depth of diffusion and the thickness of the base are commensurate, which means they can be made accurately (and the total thickness of the plate can be anything, for example 1 mm). The wafer (as is commonly called a “chip” in electronics) can be cut into individual transistors, each transistor can be tested, and good transistors can be placed in a housing.
Energy -physical quantity, which is a single measure of various forms of motion of matter and a measure of the transition of the motion of matter from one form to another.
Electron(from ancient Greek - amber]) - a stable, negatively charged elementary particle, one of the main structural units of matter.
Electricity - ordered movement of free electrically charged particles, for example, under the influence of an electric field.
Current can be alternating or constant
Alternating current, AC (eng. alternating current - alternating current) is an electric current that periodically changes in magnitude and direction.
Constant current, DC (English direct current - direct current) - electric current, the parameters, properties, and direction of which do not change (in various senses) over time, that is, the magnitude of which is constant over time.
Voltage is the potential difference between two points.
Electrical resistance- a scalar physical quantity characterizing the properties of a conductor to prevent the passage of electric current.
Electric power- a physical quantity characterizing the speed of transmission or conversion of electrical energy.
Inductance (or coefficient of self-induction) is the coefficient of proportionality between the electric current flowing in any closed circuit and the magnetic flux created by this current through the surface of which this circuit is the edge.
F - magnetic flux, I- current in the circuit, L- inductance.
Electrical capacity - characteristic of a conductor, showing the ability of a conductor to accumulate an electric charge.
Capacitor(from Lat. condensare - “compact”, “thicken”) - a two-terminal network with a certain value capacitance and low ohmic conductivity; a device for accumulating charge and energy of an electric field.
Diode(from ancient Greek δις - two and -od meaning path) - a two-electrode electronic device, has different conductivity depending on the direction of the electric current. The diode electrode connected to the positive pole of the current source when the diode is open (that is, has low resistance) is called anode, connected to the negative pole - cathode.
Transistor(eng. transistor) - a radio-electronic component made of semiconductor material, usually with three terminals, allowing input signals to control current in an electrical circuit. Typically used to amplify, generate and convert electrical signals. On circuit diagrams denoted by "VT" or "Q".
