A computer

Determination of characteristics of electronic devices and devices. Electronic devices; their static characteristics and operating parameters, operating modes

Class 2lg, 13,-„

SS Cf. No. 63799

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Zar gGGslGripped in F>cg.c iso,",reteniGs of the State Planning Committee of the USSR (\ g l.gv G.

A. G. Alexandrov

Claimed on January 31, 1941 in the People's Commissariat of Electrical Industry X 40368 (304420) Published on May 31, 1945

The present invention proposes a method for removing static characteristics electronic appliances with smooth electrostatic control.

For a number of practical purposes, it may be necessary to have the characteristics of these devices taken depending on the potential of the control electrode at constant potentials on other electrodes. For low power lamps, these characteristics are usually taken in a simple point method. Recently, a number of special devices have appeared that make it possible to immediately obtain a family of static characteristics on the screen of an electronic oscilloscope.

For powerful electrode lamps, such as powerful generator lamps, the issue of static characterization is more serious, since their electrodes, which are not designed for large overloads, are not able to withstand the powers that can be dissipated by them during full static characterization.

Further, there are a number of such lamps that are not able to withstand even those light modes in which they would be in special circuits for measuring a family of static characteristics by the oscilloscope method.

In a number of special physical studies of activated complex cathodes, for example, oxide ones, it may be necessary to measure the electron emission current in such modes that the cathode does not noticeably heat up due to the superposition of the measured current on the filament current.

These difficulties are easily resolved by using the proposed method, the essence of which can be understood from the following description and consideration of Figs. 1 – 8 drawing.

In FIG. Figure 1 shows the electron tube 1 under study, in the circuit of the control electrode of which narrow voltage pulses are periodically supplied from the resistance 14 connected in series with the source of the biasing grid voltage o blocked by the capacitance 9.

Periodic narrow voltage pulses are obtained from capacitor 25, charged from an adjustable source direct current 21 through potentiometer 22 and

¹ 63799 resistances 28 and 24. The indicated capacitor is periodically forced to discharge through the thyratron

26, which is periodically forced to ignite with the help of a peak transformer 27, the secondary circuit of which is connected in series with the bias voltage source 30 through a potentiometer 29.

To limit the grid current, a limiting resistance 28 was introduced into the grid circuit of this thyratron.

The discharge of the capacitor is carried out on a non-inductive resistance

14, included in the circuit of the control electrode of the electron lamp under study. Potentials to other electrodes are supplied from DC sources 2, 3, 4, etc., which can be controlled. These sources are blocked by sufficiently large capacitances 6, 7, 8, etc., so that when current pulses pass through these electrodes, there is no noticeable decrease in the potentials on the electrodes and, thereby, distortion of the recorded characteristics. This circumstance is of particular importance in cases where the sources supplying the electrode circuits are low-power and have high internal resistances.

The voltages of sources 2, 3, 4, 5 can be measured using DC voltmeters 31, 82, 88, 34. Pre-known non-inductive resistances 10, 11, 12, 18 are introduced into the electrode circuit, on which narrow pulses of voltage drop are obtained when passing through them narrow pulses of currents. These voltage drops are fed by the switch 15 to an auxiliary device, with which they can be measured in turn.

Auxiliary measuring device consists of a constant current source 17, a potentiometer

16, DC voltmeter 18, valve 20 and current indicator 35.

In FIG. 2, the solid line shows the time curve of the voltage present directly between the grid and the thyratron cathode 26. The dotted line in this figure shows the time curve of the bias voltage on the potentiometer 29.

In FIG. 3 shows the time curve of the voltage on the capacitor 25, charging during time 1, from the source 21 and during time 1 discharging to the resistance 4. Thus, the oscillation period is equal to t,+t,=T.

This period, in turn, is equal to the period of voltage oscillations supplied to transformer 27. The oscillations are taken forced, since in this case a clearer picture is obtained and more accurate measurements. In passing, one should also point out the fact that the use of periodic oscillations has undoubted advantages over a single impulse. The fact is that the method of periodic pulses certainly provides greater accuracy, discards the element of randomness, and, moreover, to a large extent: saves time spent on measurement.

In FIG. 4 shows the time curve of the voltage present directly between the grid and the cathode of the lamp under study. As can be seen from this graph, the grid voltage curve has the form of very narrow pulses. The maximum value of the pulse curve can be easily adjusted either by changing the voltage using potentiometer 22 or by changing the source voltage

5. In this way, it is possible to change the "voltage of the control electrode (grid).

In FIG. 5 shows in time an exemplary current pulse curve in the circuit of any of the electrodes. This curve corresponds to the curve in Fig. 4. In FIG. 6 schematically shows in time an exemplary pulse curve in the circuit of any of the highly stretched electrodes. axis of time. The same graph shows dotted lines 2, 8, 4n related to the voltage on the 63799 potentiometer 16. Three cases are shown here. Line 2 refers to the case when the voltage on the potentiometer 16 is greater than the maximum value on the corresponding non-inductive other resistance in the circuit of one or another electrode, i.e.

In this case, valve 20 will be closed, since its anode is negative with respect to the cathode.

Curve 2 in Fig. 6 refers to the case when П„ = I„,b.

This case is critical, for which the measurement is made. By measuring the voltage across the potentiometer with a voltmeter 18 in this case and knowing the given resistance K in advance, it is easy to determine the value of the current pulse 1n.

Curve 4 in Fig. 6 refers to the comparison when U„(I„, Â.

In this case, the anode of valve 20 will be positive with respect to its cathode and a current will flow through it, the average value of which will be measured by device 85. The appearance of current will serve as a sign that the critical mode has been passed and therefore it is necessary to increase the voltage on potentiometer 16.

As valve 20, you can take the smallest kenotron (diode), or a triode, in which the grid is attached to the anode. The incandescence of the kenotron should be powered from a direct current source, and the common point should be made at the negative end of the incandescent source (to avoid the influence of the non-equipotentiality of the cathode and the initial electron velocities).

In addition to the compensation method for measuring current pulses, an oscilloscope or oscilloscope method can also be used. For this purpose, shown in dotted lines in FIG. 1 conductors

86 are attached to a pair of oscilloscope deflection plates giving vertical deflection of the electron beam; the other pair of deflecting plates is connected to a source with a sawtooth voltage curve, and this source is synchronized with source 27, which supplies alternating voltage to the circuit of the thyratron grid

26. At the same time, clear voltage drop pulses will appear on the oscilloscope screen (see Fig. 5), having measured them with the help of preliminary calibration and zn; I know in advance the values of non-inductive resistances in the circuits of the electrodes, it is possible to determine the very values \u200b\u200bof the current pulses. For this measurement, it is imperative to use an electronic oscilloscope or an oscilloscope. The use of a loop electromagnetic oscilloscope should give significant errors due to the large inertia of the system.

The method of supplying pulses to the circuit of the control electrode and measuring currents in the circuit of other electrodes has a number of significant advantages. First of all, the power of the thyratron, which discharges the capacitor, decreases to a considerable extent. Then it becomes possible to measure currents in the circuit of any electrode at any potentials on other electrodes, which cannot be obtained when the current pulse is measured in the circuit of the electrode to which the potential pulse is applied.

With this method, the lamp is “unlocked” only at those moments when a potential pulse is applied to the control electrode. The rest of the time, a sufficiently large (in absolute value) negative potential is located on the control electrode.

Approximate static characteristics obtained by the proposed method are shown in the figures

Subject of invention

1. A method for measuring the static characteristics of electronic devices with smooth electrostatic control, characterized in that a voltage in the form of narrow pulses from a voltage charged from an external source and periodically forcedly discharged at using the thyratron of the capacitor, and to the other electrodes of the electronic device under test, through pre-known non-inductive resistances, apply adjustable voltages from DC sources blocked by capacitances, moreover, the resulting MQKcHMBJlbHblp. The values of the current pulses in the circuits of these electrodes are measured by the voltage drop pulses at the above resistances, to which an adjustable compensating voltage is applied through the valve and the current indicator.

2. A device for implementing the method according to claim 1, characterized by the use of one pair of deflecting electrodes, which is connected to the ends or part of the resistances introduced into the electrode circuits, and a sawtooth voltage is connected to the other pair of deflecting electrodes, synchronized with an alternating voltage source supplied to the control electrode circuit of the thyratron, periodically discharging the capacitor.

Tech. editor M. V. Snolyakva

Rep. editor D. A. Mikhailov

Printing house of Gosplannzdat, no. Vorovsky, Kaluga

L!49953. Signed for publication on November 25, 1946. Circulation: 500 copies. Price 65 kop. Zach. 325

Here you go to the teapot in joy with the idea of popping a mug of tea with a bagel in honor of the newly assembled device, but it suddenly stopped working. Wherein visible reasons no: the capacitors are intact, the transistors do not seem to smoke, the diodes too. But the device does not work. How to be? You can use this simple troubleshooting algorithm:

Mounting "snot"

"Snot" are small drops of solder that create short circuit between two different tracks on a PCB. During home assembly, such unpleasant drops of solder lead to the fact that the device either simply does not start, or does not work correctly, or, worst of all, expensive parts immediately burn out after being turned on.

In order to avoid such unpleasant consequences, before turning on the assembled device, you should carefully check printed circuit board for short circuits between tracks.

Instruments for device diagnostics

The minimum set of devices for adjusting and repairing amateur radio structures consists of, a multimeter and. In some cases, you can get by with just a multimeter. But for more convenient debugging of devices, it is still desirable to have an oscilloscope.

For simple devices such a set is enough for the eyes. As for, for example, debugging various amplifiers, for their correct setting It is desirable to have also a signal generator.

Proper nutrition is the key to success

Before drawing any conclusions and the performance of the parts included in your amateur radio design, you should check whether the power is being supplied correctly. Sometimes it turns out that the problem was in the wrong diet. If you start checking the device with its power, you can save a lot of time on debugging if the reason was in it.

Diode test

If there are diodes in the circuit, then they should be carefully checked one by one. If they are outwardly intact, then you should unsolder one terminal of the diode and check it with a multimeter switched on in the resistance measurement mode. Moreover, if the polarity of the terminals of the multimeter coincides with the polarity of the diode leads (+ terminal to the anode, and - terminal to the cathode), then the multimeter will show approximately 500-600 Ohms, and in the reverse connection (- terminal to the anode, and + terminal to the cathode) does not will show nothing at all, as if there is a break. If the multimeter shows something else, then most likely the diode is out of order and unusable.

Checking Capacitors and Resistors

Burnt resistors can be seen immediately - they turn black. Therefore, finding a burned-out resistor is quite easy. As for capacitors, their verification is more difficult. First, as in the case of resistors, you need to inspect them. If they do not outwardly cause suspicion, then they should be desoldered and checked with an LRC meter. Electrolytic capacitors usually fail. However, they swell when burned. Another reason for their failure is time. Therefore, in older devices, all electrolytic capacitors are often replaced.

Checking transistors

Transistors are tested in the same way as diodes. First, an external examination is carried out and if it does not cause suspicion, then the transistor is checked with a multimeter. Only the terminals of the multimeter are connected in turn between the base-collector, base-emitter and collector-emitter. By the way, transistors have an interesting malfunction. When checking, the transistor is normal, but when it is included in the circuit and power is supplied to it, then after a while the circuit stops working. It turns out that the transistor has heated up and behaves like a broken one when heated. Such a transistor should be replaced.

Electronic devices, which form the basis of electronics, can be classified according to two criteria:

According to the principle of work;

By functionality.

According to the principle of work electronic devices can be divided into four classes:

1. Electronic devices – the flow of electrons moves between the electrodes, which are in a high vacuum, i.e. in an environment of such a rarefied gas that the moving electrons do not experience collisions with gas particles.

2. Gas discharge devices - the movement of electrons in the interelectrode space occurs under conditions of their collision with gas particles (with molecules and atoms), which under certain conditions leads to gas ionization, which dramatically changes the properties of the device. Such devices are called ionic.

3. Electrochemical devices - the principle of operation is based on the phenomena associated with the origin of electric current in liquid bodies with ionic conductivity. Such devices operate on the basis of phenomena studied by electrochemistry and electronics - chemotronics.

4. Semiconductors - the principle of operation is based on electronic phenomena in substances that have a crystalline structure, which is characterized by a regular and ordered arrangement of atoms in space. The interconnected atoms are arranged in a strictly defined way, which forms crystal lattice solid body.

By function electronic devices can be divided into three groups:

1. Electrical converters - these are devices in which electrical energy of one type (for example, direct current) is converted into electrical energy of another type (for example, alternating current various shapes). These include rectifying, amplifying, switching, stabilizing devices, etc.

2. Electric lighting are devices in which electrical energy is converted into optical energy. These include electronic light indicators, CRT, sign indicators, lasers, incl. light emitting diodes, etc.

3. photovoltaic are devices in which the energy of light radiation is converted into electrical energy. These are photocells, photodiodes, phototransistors, video cameras, etc.

Common to all electronic devices is that they convert energy various kinds, so devices that have significant differences in principle, are used for the same functional purpose, i.e. for the same purpose and have similar properties.

The type of static characteristic is usually given technical requirements.
Static characteristics. a-input. b-transmission. in-weekend. / - at the output O. 2 - at the output 1 ..
The type of static conversion characteristic is determined by the scheme and design of the measuring instrument.
Dependencies Q (U for a synchronous motor at R. The type of static load characteristics is determined by the parameters of power receivers and the effect of losses in the elements of the distribution network, including transformers.
View of the static characteristics of amplifiers with external and internal feedback practically the same.
Schemes of high-frequency conductometric cells.| Equivalent electrical circuits capacitive measuring cell. The type of static characteristic of a high-frequency conductometer is determined mainly by the dependence of the electrical properties of the cell - its active and reactive conductivity - on the electrical conductivity of the solution. An analytical study of the electrical properties of cells is carried out using their equivalent circuits, in which distributed cell parameters with - a certain degree of accuracy are replaced by lumped circuit elements. Such an analysis allows, in a number of cases, to qualitatively evaluate the type of static characteristics of the device in order to select the geometric parameters of the cell and the frequency of the generator, which would ensure the measurement of electrical conductivity in a given range.
The type of static characteristic of a high-frequency conductometer is determined mainly by the dependence of the electrical properties of the cell - its active and reactive conductivity - on the electrical conductivity of the solution.
Structural scheme measuring transducer. The type of static characteristic is affected by such factors as mechanical hysteresis, creep, friction forces, l, and some others. The conversion of the measured value x into the output value y is very rarely possible to obtain directly with a single-element converter. Most often, it is carried out using a certain set of simple elements. If we assume that each element included in the converter can also be represented as a quadripole, then the converter as a whole will be depicted as certain combination such quadripoles - elements. Such combinations may have a different structure, however, as a rule, this serial connection quadripoles (cassock. For such a circuit, it is characteristic that the output value of each k - ro quadripole is simultaneously the input value ( & 1) - th. At the input of the chain of quadripoles, the input value x acts, and at the output - y.
However, the relay type of the static characteristics of such amplifiers often adversely affects the quality of regulation.
Consider the form of the static characteristic of a linear closed-loop system of combined control and load regulation.

An analysis of the type of static characteristics of a semiconductor triode shows that the main nonlinear parameter of the triode is its input resistance. The resistance rk and the transfer coefficient a in the active region of the characteristics of the triode are practically constant.
By type of static characteristic: linear (without initial signal at Sx and with initial signal at y0 Sx), non-linear (with rising or falling characteristic), relay.
According to the type of static characteristics, objects are divided into stationary and non-stationary.
According to the type of static characteristic, sensors can be divided into linear (without an initial signal at S x and with an initial signal at Uo S x), non-linear (with a rising or falling characteristic), relay.
According to the type of static characteristic, the input - output elements automatic systems are divided into elements of continuous and elements of discrete action.
According to the type of static characteristic, relays are divided into two large groups: neutral and polarized. In neutral relays, the direction of movement of the armature does not change, and therefore, the switched circuits do not switch when the polarity of the input signal changes. In polarized relays, the direction of movement of the armature changes and, therefore, the switched circuits switch to other contacts when the polarity of the input signal changes.
Secondly, the type of static characteristics of the transistor depends on the scheme of its inclusion. Obviously, for any switching circuit, the physical processes occurring in the transistor do not change, but the input and output values change significantly, and hence the static characteristics of the transistor.
Scheme for removing the static characteristics of an electron tube with the anode circuits powered from a source. There are four types of static characteristics: anode, anode-no-grid, grid-anode and grid.
Thus, the shape of the curves of static characteristics for most elements is similar to the curves of the dependence of the intensity of the helium lines on the current, with the only difference that they reveal the current of the start of evaporation.
Depending on the type of static characteristic, analog and relay ohmic elements are distinguished.
Scheme for the study of the triode. There are two main types of triode static characteristics: anode characteristics, depicting the dependence of the triode anode current on the anode voltage at a constant grid voltage, and anode-grid characteristics, depicting the dependence of the anode current on the grid voltage at a constant anode voltage. When taking characteristics, it is necessary to maintain a constant filament voltage.
There are two main types of triode static characteristics: 1) anode characteristics, which are the dependence of the triode anode current on the anode voltage at a constant grid voltage, and 2) anode-grid characteristics, which are the dependence of the anode current on the grid voltage at a constant anode voltage . During characterization, the cathode filament voltage must be constant.
A graphical model in the form of a static characteristic of a non-linear element is determined experimentally by applying a constant voltage or current to the element, the values of which are adjusted so as to obtain all points of the characteristic.

Experiments show that the type of static characteristics and the gains of amplifiers with external feedback and with self-saturation are quite close.
Let us consider the effect of displacement on the form of the static characteristic of a reversible magnetic amplifier. On fig. 24.10 shows the construction of a static characteristic of a reversible magnetic amplifier at different offset values.
There are three types of static characteristics for a link.
The function f depends on the type of static characteristic of controlled conductivity.
The main disadvantage of such amplifiers is the relay type of the static characteristic.
On fig. 30, b shows the view of the static characteristics of the compressor for the case of pH const and three values of PBC (pBct Pvsg Pve) - In the spool position I Yat, the compressor operates at full capacity Qi, Q2 or Q3, depending on PBC. As the spool extends (R decreases), the cooling capacity decreases approximately linearly.
In measurement practice, depending on the type of static characteristic of the transducer and the type of work, this definition is given a more specific form, as a result of which several narrower and more specific concepts of sensitivity are used.
Static characteristics of the amplifier nozzle - damper with constant differences on the chokes. Here we consider the influence of a constant difference on the form of the static characteristic of a pneumatic amplifier. Assume that there is a device that automatically maintains a constant differential pressure D / 7PS at a constant throttle. The static characteristic of the amplifier under consideration is the same as the static characteristic / of a conventional amplifier. Therefore, the working section of the static characteristic 2 has an increased steepness.
Schemes and static characteristics of PD. The law of transformation of displacement into an electrical signal (or the type of static characteristic of the PD) is determined by the design of the sensor (the profile of the potentiometer frame), the connection scheme to the power source and load, as well as the operating mode. In a particular case, the PD implements the relay law for converting displacement into voltage. Such a PD is called a relay potentiometric sensor.
The position of the switching surfaces depends on the properties of the relay element (type of static characteristics, delay times during operation and release), on the acting forces (type of the mechanical characteristics of the motor and the law of change of the load torque) and on the type of control function.
Let us make some assumptions that will not fundamentally affect the form of the static characteristic. GTcTGT, i.e. the amount of heat added to the fuel. At constant fuel consumption, this term is constant and small compared to the GTXT term.
The static characteristic of the on-off controller (a, the change in the control action x (b) and the transient process y (c) when asymmetric self-oscillations occur in the system.
The actuation moments of the PZ controller are determined by the properties of the linear part of the ASR and the type of the static characteristic of the controller.
In this case mathematical description of an object can be represented as a static characteristic describing the entire range of operating modes, as well as a set of dynamic characteristics, each of which approximately describes the dynamic properties of the object modes corresponding to a certain number of the static characteristic.
The nature of the change / 2 f (Un) is influenced by the type of static load characteristic, especially in terms of reactive power, since the regulatory effect of reactive power is greater than that of active power.
Block diagram of the automatic control system for the temperature in the processing zone and elastic displacements that fluctuate in the AIDS system. It is clear that in this case the resulting static characteristic is determined by the type of static characteristics of all devices.
Therefore, the demands of the energy consumer and the intentions of the machine designer, embodied in the form of a static control characteristic of one form or another, must be consistent with the initial cost of automatic control mechanisms and with the operating costs of maintaining these mechanisms.
Let us formulate the principles for constructing control systems for a class of technological objects, the distinctive feature of which is the extreme form of the static characteristic. The class of such objects is very wide and includes installations operating in many important sectors of the national economy - chemical, petrochemical, metallurgical, etc. Optimal management of these objects can provide a significant economic effect.
To analyze the quality of inkjet logical elements and matching of elements in circuits, the following three types of static characteristics are usually used: switching characteristics, output and input.
Consequently, the segments cut off on axis 6 do not depend on k and are determined by the type of the static characteristic of the relay.
Dynamic characteristics of a cascade with an active-reactive load for a sinusoidal input signal. It is easy to see that the type of dynamic characteristics for an active-reactive load depends not only on the nature of the resistance and the type of static characteristics of the amplifying element, but also on the frequency, amplitude and shape of the input signal.
The distribution accuracy of the motors between the U and Uz busbars (see Fig. 6 - 9) has little effect on the form of static characteristics, but affects the critical voltage.

cathode ray tubes; their scope and application. Ionic (gas-discharge) devices: their main parameters.

electron beam devices (ELP) - a class of vacuum electronic devices that use a stream of electrons concentrated in the form of a single beam or a beam of rays, which are controlled both by intensity (current) and by position in space, and interact with a stationary spatial target (screen) of the device. The main scope of ELP - conversion optical information into electrical signals and inverse transformation an electrical signal into an optical one - for example, into a visible television image.

In the class of electron-beam devices not x-ray tubes, photocells, photomultipliers, gas-discharge devices (dekatrons) and receiving-amplifying devices are switched on electronic lamps(beam tetrodes, electric vacuum indicators, lamps with secondary emission, etc.) with a beam form of currents.

Device

An electron beam device consists of at least three main parts:

· Electronic projector(gun) forms an electron beam (or a beam of beams, for example, three beams in a color kinescope) and controls its intensity (current);

· deflection system controls the spatial position of the beam (its deviation from the spotlight axis);

· Target(screen) of the receiving ELP converts the energy of the beam into the luminous flux of the visible image; the target of the transmitting or storing ELP accumulates a spatial potential relief read by a scanning electron beam.

Classification

Transmitting cathode-ray devices convert the optical image into an electrical signal.

Dissector (“instant action tube”) - historically the first type of transmitting tube used for astronomical observations, in industrial automation devices and for document scanning;

· Iconoscope - historically the first type of transmitting television tube;

· Ortikon, superortikon, vidicon - the main types of transmission tubes used in television before the transition to solid-state converters;

· Specialized devices, for example, a monoscope - a tube for converting a still image signal into an electrical signal (test chart).

Receiving cathode-ray devices convert an electrical signal into an optical (visible) image:

Oscilloscope tube - ELP with capacitive (oscilloscope) control of the beam position, used to visualize the shape of electrical signals

· Kinescope - a receiving tube of a television system with a magnetic deflection system and horizontal scanning of the image;

· Indicator cathode-ray tube - receiving tube radar system with a magnetic deflection system and a circular sweep, as well as a variety of specialized indicators, character-generating tubes, etc.

· Character-generating (character-printing) tubes (charaktron, typotron and their analogues).

· A memory tube records information on a spatial target, stores it for a specified time, and (in tubes with reading) reproduces or reads it with an electron beam. Various pipes of this subclass were used both for storing, processing and playing optical imaging, and as binary storage devices of early computers

Electronics- a field of science and technology that studies and applies devices whose operation is based on the flow of electric current in a vacuum, gas and solid. The high speed and high reliability of electronic devices have led to their widespread use in computer science, radio engineering, communications, navigation, industry, etc. With the help of electronic devices, the electrical energy of the power source is converted into the energy of a useful signal (amplifiers, signal generators, etc.), alternating current is converted into direct current (rectifiers) and direct current into variable (inverters), energy conversion, voltage, frequency adjustment, etc.

In electronic devices the conversion of electrical energy and signals is carried out using electronic devices (electronic active elements). In addition to electronic devices, they use power supplies and passive components: resistors, capacitors, inductors.

At present, semiconductor electronic devices are mainly used. They carry electric charges occurs in a solid state (semiconductor). These include diodes, transistors, thyristors, etc.

semiconductor diode(Fig. 1) is a two-layer structure that is formed in one crystal. One layer is n-type and the other is p-type. In general, this structure is called p-n-junction or electron-hole transition. The main property of an electron-hole transition is its one-sided electrical conductivity.

Fig.1. Semiconductor diode: a) semiconductor structure of the diode;

b) conditional graphic designation; c) volt - ampere characteristic

With direct mixing p-n transition and its electrical conductivity increases and a current passes through the junction, which strongly depends on the applied voltage. With a reverse bias of the pn junction, the electrical conductivity of the junction decreases and electricity practically does not pass through it.

A semiconductor diode with a reverse biased p-n junction, in which, with relatively small changes in the reverse voltage in a region close to the breakdown voltage, the reverse current increases sharply, is called zener diode(Fig. 2). It is used in the creation of voltage stabilizers.

Fig. 2. Semiconductor zener diode: a) conventional graphic designation; b) volt - ampere characteristic

Varicap called a semiconductor diode with a reverse biased p-n junction, used as a variable capacitor for electronic tuning of frequency-selective circuits (Fig. 3).

Fig.3. Semiconductor varicap: a) conventional graphic designation;

b) volt - farad characteristic

Semiconductor triodes (transistors) are divided into bipolar and field.

bipolar transistor called a semiconductor device with two pn junctions (Fig. 4). It has a three-layer structure of n-p-n- or p-n-p-type. The middle region between two pn junctions is called the base. Its thickness is made quite small. The adjacent regions are called emitter and collector. Accordingly, the p-n junction emitter-base is called emitter, and the base-collector junction is called collector.

Fig.4. Semiconductor structure and conventional graphic designation of bipolar transistors: a) n-p-n-type; b) p-n-p-type

FET a semiconductor device is called, the resistance of which changes under the action of a transverse electric field created by a control electrode (gate) adjacent to the conducting volume of the semiconductor. There are two types of field-effect transistors: with a control p-n junction(Fig. 5) and insulated gate(Fig. 6).

Fig.5. Semiconductor structure and conventional graphic designation of a field-effect transistor with a control p-n-junction: a) with an n-type channel; b) with a p-type channel

Fig.6. Semiconductor structure and conventional graphic designation of a field-effect transistor with an insulated gate: a) with a built-in channel; b) with an induced channel

Unlike bipolar transistors, in which charge transfer is controlled by changing the base current, in a field-effect transistor, current is controlled by changing the control voltage, which regulates the width of the channel through which the current passes. The area of the channel, from which the movement of carriers begins, is called the source, and the area to which the main carriers move is called the drain. The control area in the instrument that spans the channel is called the gate. By changing the voltage between the gate and the source, the channel cross section is changed.

Multilayer structures with three p-n junctions are called thyristors. Their main property is the ability to be in two states of stable equilibrium: maximally open (with high conductivity) and maximally closed (with low conductivity). For this reason, they perform the function of a contactless electronic key with one-sided conduction. Thyristors with two terminals (two-electrode) are called diode thyristors (dinistors), and with three (three-electrode) - or triode thyristors (trinistors), or symmetrical thyristors (triacs), if they are able to conduct current in both directions (Fig. 7).

Fig.7. Thyristors: semiconductor structure: a) diode thyristor (dinistor); d) trinistor; g) symmetrical thyristor (triac); conditional graphic designation: b) diode thyristor; e) trinistor; h) triac; volt-ampere characteristics: c) diode thyristor; e) trinistor; i) triac

Semiconductor photocells include: photoresistor, photodiode, phototransistor, photothyristor, LED (Fig. 8).

Fig. 8. Conditional graphic designation of semiconductor photocells: a) photoresistor; b) photodiode; c) phototransistor; d) photothyristor; e) LED

photoresistor A semiconductor device is called, the resistance of which depends on the illumination. With increasing illumination, the resistance of the photoresistor decreases.

The principle of operation of the photodiode is based on the increase of the inverse current p-n transition when illuminated. The photodiode is used without an additional power source, since it is itself a current generator, and the current strength is proportional to the illumination.

In a phototransistor The p-n collector-base junction is a photodiode.

LEDs emit light when a direct current passes through them. The brightness of the glow is proportional to the forward current.

If an LED and a photosensitive element, such as a phototransistor, are combined in one package, then the input current can be converted into an output current with complete galvanic separation of the circuits. Such optoelectric elements are called optocouplers(Fig. 9).

Fig. 9. Conventional graphic designation of semiconductor optocouplers:

a) resistor; b) diode; c) transitory; d) thyristor

In addition to photoresistors, the most common semiconductor resistors include: thermistors and varistors, whose resistance changes with temperature and applied voltage, respectively (Fig. 10).

Fig. 10. Conditional graphic designation of semiconductor resistors: a) thermistor; b) varistor

With the help of the considered electronic devices, the necessary conversions of electrical energy and signals are carried out. Most simple view conversion is AC rectification, more complex - inverting DC to AC, amplifying, generating and converting signals of various shapes.

Rectifiers convert the alternating voltage of the mains into a constant voltage at the load (Fig. 11). They are used as secondary power sources. AC supply voltage using power transformer is reduced or increased to the required value, and then straightened with a rectifier. As a result, the output of the rectifier produces a voltage of a constant direction, which is pulsating (i.e. varies in time in value) and therefore unsuitable for powering most electronic devices.

Fig.11. Structural diagram of the rectifier

To reduce the ripple of the rectified voltage at the output of the rectifier, a smoothing filter is included, and in some cases a DC voltage stabilizer is additionally introduced.

Main rectifier circuits can be subdivided into half-wave(Fig. 12) and full-wave(Fig. 13).

Fig. 12. Schemes and timing diagrams of half-wave rectifiers: a) single-phase; b) three-phase

Fig. 13. Full-wave rectifiers: single-phase rectifiers: a) bridge circuit; b) with output from the midpoint of the transformer winding; c) their timing diagrams; three-phase rectifier; d) three-phase bridge circuit; e) its timing diagram

Smoothing filters only the direct component of the rectified voltage is passed to the output and its variable components are attenuated as much as possible. In the simplest case, a smoothing filter can contain only one element - either a high inductance choke connected in series at the rectifier output, or a high capacitance capacitor connected in parallel with the load (Fig. 14).

Fig.14. Smoothing filters: a) inductive; b) capacitive; c) their timing charts

Voltage stabilizer called a device that maintains the voltage on the load with a given accuracy when the load resistance and mains voltage change within certain limits (Fig. 15). The voltage that the stabilizer supports is set by the reference element - the zener diode (Fig. 2).

Fig. 15. Scheme and timing diagrams of a parametric voltage regulator

Amplifier called a device designed to increase the amplitude and power of the input signal without changing its other parameters. An increase in the amplitude and power of the signal at the output of the amplifier is achieved by converting the energy of the DC power supply into the energy of the output alternating signal. In general, electronic amplifiers are multistage devices. Separate cascades are interconnected by circuits, through which an alternating (amplified) signal is transmitted and the constant component of the signal is not passed. Cascades are performed according to the scheme with a common emitter and a common source, with a common collector and a common drain, with a common base and a common gate (Fig. 16).

Fig.16. Circuits for switching on transistors with a common (s): a) emitter;

b) collector; c) base; d) source; e) runoff; e) shutter

The circuit of any cascade consists of a power source, a transistor, and bias circuits that ensure the operation of the transistor in direct current, i.e., the rest mode (Fig. 17).

Multistage amplifiers are a series connection of the same type of amplifying stages.

In integrated amplifiers, a direct connection between stages is used. Such amplifiers can amplify arbitrarily slowly varying signals and even DC signals and are therefore called DC amplifiers. Modern amplifiers DC amplify signals in a very wide frequency spectrum and belong to the category of broadband amplifiers.

Fig. 17. Amplifier circuits: a) on a bipolar transistor; b) on a field effect transistor

The disadvantage of amplifiers with direct connections is the change in the output voltage of the rest mode (zero drift) due to the instability of the supply voltage, temperature and other factors. An effective way to reduce zero drift in such amplifiers is to use differential amplifier stages.

Differential Amplifier is designed to amplify the difference between two input signals and is a symmetrical two-transistor circuit with combined emitters, having two inputs and two outputs (Fig. 18).

Fig.18. Differential Amplifier

Operational amplifier(Fig. 19), like any other amplifier, is designed to amplify the amplitude and power of the input signal. It received the name "operational" from analogues on discrete elements that performed various mathematical operations (summation, subtraction, multiplication, division, logarithm, etc.) mainly in analog computers. Currently, the operational amplifier is most often performed in the form of an integrated circuit.

Fig. 19. Operational amplifier

Electronic generators called self-oscillating (self-excited) systems in which the energy of the power source (direct current) is converted into the energy of an alternating signal of the desired form.

In sinusoidal voltage generators transistors operate in amplifying mode. Unlike them in pulse generators transistors operate in a key mode (when the transistor is alternately in full open, then in full closed state). In the open state, the transistor passes the maximum current and has a minimum voltage at the output, determined by its residual voltage. In the closed state, its current is minimal, and output voltage maximum and close to the power supply voltage. Such an element is called transistor key(Fig. 20).

Fig. 20. Schemes transistor switches: a) on a bipolar transistor; b) on a field effect transistor; c) their timing charts

Multivibrators- These are pulse generators with positive feedback, in which amplifying elements (transistors, operational amplifiers) operate in a key mode.

Multivibrators do not have a single state of stable equilibrium, therefore they belong to the class of self-oscillating generators and are performed on discrete transistors, integrated logic elements and operational amplifiers (Fig. 21).

Fig.21. Schemes of self-oscillating multivibrators: a) on discrete elements; b) on integral logic elements; c) on an operational amplifier; d) their timing charts

integrated circuit(IC) is a collection of several interconnected transistors, diodes, capacitors, resistors, etc. It is manufactured in a single technological cycle (i.e. simultaneously), on the same supporting structure - the substrate and performs a certain function of converting electrical signals .

Components that are part of the IC and cannot be separated from it as independent products are called IC elements or integral elements. In contrast, structurally separate devices and parts are called discrete components, and nodes and blocks built on their basis are called discrete circuits.

High reliability and quality combined with small size, weight and low cost of integrated circuits ensured their wide application in many fields of science and technology.

The basis of modern microelectronics is semiconductor integrated circuits. Currently There are two classes of semiconductor integrated circuits: bipolar and MIS.

The main element of bipolar ICs is an n-p-n-transistor: the entire technological cycle is oriented towards its manufacture. The remaining elements are manufactured simultaneously with this transistor without additional technological operations. For example, resistors are made with an npn transistor base layer, so they have the same depth as the base layer. Reverse-biased p-n junctions are used as capacitors, in which the n-layer corresponds to the collector layer of the n-p-n transistor, and the p layer corresponds to the base layer.

logical elements called electronic devices, performing the simplest logical operations: NOT, OR, AND (Fig. 22).

Fig.22. Conventional designation and truth tables of the simplest logical elements: a) NOT; b) OR; in and

Logical functions and logical operations on them are the subject of the algebra of logic, or Boolean algebra. The algebra of logic is based on logical quantities, which are denoted by the Latin letters A, B, C, D, etc. A logical quantity characterizes two mutually exclusive concepts: there and not, true and false, on and off, etc. If one of values of a logical value is denoted by A, then the second is denoted by "not A".

For operations with logical values, it is convenient to use a binary code, setting A=1, "not A"=0 or, conversely, A=0, "not A"=1. AT binary system calculus, the same circuit can perform both logical and arithmetic operations. If the concept of “not A” is denoted by a special letter, for example, B, then the relationship between B and A will look like: B = .

This is the simplest logical function, which is called negation, inversion, or the NOT function. A circuit providing this function is called an inverter or a NOT circuit.

Circuits OR (disjunctor) and AND (conjuncator) can be made on resistors (resistor logic), on diodes (diode logic), on transistors (transistor logic). Most often, these circuits are used in combination with an inverter, and then they implement the functions OR-NOT, AND-NOT (Fig. 23).

Fig.23. Conventional notation and truth tables:

a) Pierce arrow; b) Schaeffer stroke

The OR-NOT (Pierce's arrow) and AND-NOT (Sheffer's stroke) functions are the most common, since any other logical function can be implemented on their basis. The number of variables, and hence the number of inputs for the corresponding circuits, can be equal to two, three, four or more. In logic elements, logical zeros and ones are usually represented by different voltage values: voltage (or zero level) U 0 and voltage (or one level) U 1 . If the one level is greater than the zero level, then the circuit is said to operate in positive logic, in otherwise(U 1< U 0) она работает в отрицательной логике. Никакой принципиальной разницы между положительной и отрицательной логиками нет. Более того, одна и та же схема может работать и в одной, и в другой логике.

The most widely used is the NAND circuit of the TTL type (transistor-transistor logic).

Combining logic OR-NOT or AND-NOT, you can create various devices both with and without memory.

To digital devices with memory include: triggers, counters, registers.

triggers devices are called devices that have two states of stable equilibrium and are able to jump from one stable state to another every time the control input signal exceeds a certain level, called the threshold.

There are several types of triggers: RS, D, T, JK, etc., which are produced by the industry in the form of separate microcircuits, and are also performed on the basis of logical elements AND-NOT or OR-NOT (Fig. 24).

Fig. 24. Conditional graphic designations of triggers: a) RS-trigger based on logical elements OR-NOT; in the form of separate microcircuits: b) RS flip-flop; c) D-trigger; d) T-trigger; e) JK flip-flop

In devices digital processing information, the measured parameter (angle of rotation, speed, frequency, time, temperature, etc.) is converted into voltage pulses, the number of which characterizes the value of this parameter. These impulses are counted impulse counters(Fig. 25, a) and are expressed as numbers.

Fig. 25. Conventional graphic symbols: a) pulse counter;

b) register; c) decoder; d) encoder; e) multiplexer;

f) arithmetic logic unit

Registers called the functional units of digital devices designed to receive, store, transmit and convert information (Fig. 25, b).

To digital devices without memory include: decoders, encoders, multiplexers, demultiplexers, etc.

decoder a device is called that produces a single signal at only one of its outputs, depending on the code of the binary number at its n inputs (Fig. 25, in).

Encoder(Fig. 25, G) performs the inverse function of the decoder.

Multiplexer is a device for switching one of the information inputs to one of its outputs, depending on the binary code at its m address inputs (Fig. 25, d).

Demultiplexer performs the inverse function of a multiplexer.

Depending on the number of elements on one chip, they speak of a different degree of integration of the IC. A large integrated circuit (LSI) contains several million elements on one chip (in one package) and performs the functions of complex devices. It is a functional finished product.

LSI, which includes at least the main processor nodes: an arithmetic logic unit (Fig. 25, e), command decoder and control device, is called microprocessor. It may include other blocks that expand the capabilities of the microprocessor. The microprocessor is used for logical processing, storage and transformation of data. It is a semiconductor device that is universal in its capabilities and can be used in control systems for complex devices.

Related questions

1. What does electronics study?

2. What devices are called electronic?

3. How do semiconductor materials differ from conductors and dielectrics?

4. How is the p-n junction arranged? What is the main property of the junction that makes it possible to manufacture semiconductor devices on its basis?

5. How does a diode work? What kind does it have volt-ampere characteristics?

6. How does a bipolar transistor work and how does it work?

7. How does a FET work? How is it different from a bipolar transistor?

8. What are the names and what are the conclusions of the bipolar and FET?

9. What is voltage stabilization based on a zener diode? What are the characteristics of zener diodes?

10. How to convert sinusoidal voltage to DC?

11. How do diode rectifiers work?

12. How they work electrical filters?

13. How to get a stable constant voltage?

14. What are electrical signal amplifiers used for?

15. What is the principle of amplifying current and voltage?

16. What is the difference between transistor amplifiers and integrated circuit amplifiers?