Detectors of electrical oscillations. Electrical vibration detectors Device for detecting electrical vibrations

Wireless telegraphy, 1914

The detectors used in radiotelegraphy can be divided into two classes: driven by current or voltage. Voltage-driven detectors are always connected in parallel with the capacitor because there is a large potential difference across the terminals of the capacitor, and current-driven detectors are connected in series with the capacitor. Detector types can be further subdivided into different classes, namely:

poor contact detectors, such as the Marconi coherer;
rectifier detectors such as the Fleming lamp and the carbide detector;
electrolytic detectors, such as Fessenden and Shlomilch detectors;
thermoelectric detector, based on a pair of galen and graphite or other pairs;
detector based on changes in magnetic properties - Marconi magnetic detector.

Coherer

The coherer is the result of the work different people- Hughes, Lodge, Branly, Popov and others. It consists of a small amount of metal filings placed between two electrodes. The first practical example of a coherer for radiotelegraphy was created by Marconi. It consisted of a small amount of nickel filings and a small percentage of silver filings added to them, placed between silver electrodes having bevelled ends, so that the space between them into which the filings were placed was wedge-shaped.

The purpose of electrodes of this form is to be able to control the sensitivity of the coherer. The greatest sensitivity is achieved when the elongated parts of the wedges are located below, and vice versa, if they are turned over by 180°, then the sensitivity of the coherer will be minimal.

The electrodes and metal filings are placed in a sealed glass tube, in which a slight vacuum is created. The electrode contacts, to which the wires are connected, are removed from the tube using pressure seals ( rice. 1.).

Rice. 1. Marconi coherer.

The principle of operation of the coherer is based on the fact that if a voltage greater than a certain value appears on its outputs, then the resistance of the coherer, which is quite high due to poor contact between metal filings and electrodes, drops sharply to a much lower value. Some think this is due to the electrostatic attraction between the metal filings; others believe that microscopic sparks jump between the sawdust, which slightly weld the sawdust together. However, for whatever reason this did not happen, the important fact is that if the coherer is subjected to a potential difference when any signal is applied to it, then its resistance drops very much, and if the coherer is connected in series with the relay and the power battery, and the contacts relays switch the recorder, then the presence of electrical fluctuations will be recorded on paper, since the relay will close every time there are electrical fluctuations. However, the coherer itself does not restore its previous high resistance state, so a small electromagnetic hammer is used to gently tap the underside of the coherer, shaking the iron filings, which causes the former high resistance to be restored and again makes the coherer sensitive to electrical fluctuations.

Rice. 2. Diagram of a Marconi receiver with a coherer.

On Rice. 2 shows a diagram of a Marconi receiver with a coherer. The antenna circuit consists of a tuning inductance and the primary winding of a resonant transformer connected in series and connected to the antenna and ground. The secondary winding of a resonant transformer consists of two parts connected in series with each other by a capacitor, which prevents the passage direct current through windings. The ends of the windings of the secondary coil are connected to the terminals of a variable capacitor, with which the winding is tuned to the resonant frequency of the primary winding, and a coherer is connected in parallel with this capacitor.

The relay and the battery, connected in series, are connected in parallel with the capacitor, which connects both parts of the secondary winding of the resonant transformer. A battery of elements connected to the recorder (Morse code printer) is connected to the relay contacts, and an electromagnetic hammer is connected in parallel to the recorder, by which the coherer is brought to its original high-resistance state after it has worked as a result of the action of a high-frequency signal.

Due to the high self-inductance of the relay, recorder and hammer coils, it is important that these, as well as the relay and hammer contacts, be shunted with a high non-inductive resistance to eliminate possible sparking that can lead to false operation of the coherer.

Setting various schemes and parts of the apparatus described above are generally considered hard work, but if you treat the setting systematically, then it is quite simple to perform it. The operator must proceed as follows: first, with the adjusting screw, set the hammer magnet as far away from his armature as possible, and then adjust the hammer handle so that it is about one millimeter away from the coherer.

Next, turn the relay adjusting screw to close the circuit, and then slowly turn it in the opposite direction until the circuit opens. Now transmit some text with the buzzer (the buzzer is a small battery-powered interrupter that generates small electrical vibrations) and at the same time bring the hammer magnet closer to its armature until the blows are strong enough to be able to It was clear to receive Morse code signals.

If the hits are too weak, then the received signals will merge, and if the hits are too strong, they will break the signals, that is, the dash will look like a series of dots. The entire apparatus described above, with the exception of the recorder, is enclosed in a metal box, which prevents damage to the coherer by powerful signals that appear in the circuits during the operation of the transmitter.

Rice. 4. Lodge-Muirhead coherer.

This is a coherer that can be used both with a telephone and with a recorder, it is arranged as follows: a small metal cup ( rice. 4) contains a ball of mercury, on which a small drop of oil is located, forming an infinitely thin insulating film over it. Above the ball of mercury is a small iron disk with a sharp edge, this disk slowly turns. With the help of an adjusting screw, the lower edge of the disc is lowered until it comes into contact with the oil film on the surface of the mercury, but if the pressure is not too high, then the oil film will not be damaged. A galvanic cell and headphones or a recorder are connected in series with the coherer. When an electrical signal passes through the circuit, as a result of the breakdown of a thin film of insulation, the coherer becomes conductive and, as a result, the current of the galvanic cell activates the headphones or recorder. This type of coherer recovers itself and does not require shaking.

This detector consists of a platinum cup containing a dilute acid solution. The cup is one electrode, the other electrode consists of a Wollaston wire (it is a platinum wire, with a thickness of less than 0.01 mm, coated with silver), sealed in a glass tube, which is slightly immersed in a solution so that the very tip of the Wollaston wire is there. . Connection to wires is carried out using metal pipe in which the electrodes are installed. The detector is connected in series with high-resistance telephones to the moving contact of the potentiometer, the extreme terminals of which are connected to the battery. A small current that passes through the detector polarizes it - gas is formed on the electrodes, as a result of which the resistance of the detector increases. If now the device is subjected to alternation of small potentials and currents coming from the receiving circuit, then under the influence of electrical oscillations, depolarization will occur and the resistance of the electrolytic cell will drop, a small current will pass through the telephones, audible by the operator. After the signal passes through the circuit, the battery polarizes the cell again, that is, the device is self-healing. To adjust the cell, a small electrode is inserted into the holder and its tip is immersed in the electrolyte, the potentiometer knob is turned until a hissing sound appears in the headphones, then the knob is turned in the opposite direction until the noise stops. At this point, the detector has the highest sensitivity.

This type of detector is widely used and is very sensitive and reliable. However, strong atmospheric interference has been found to temporarily desensitize the device, but not for long, as the coherer will self-repair after a few seconds. Recovery can be accelerated by briefly increasing the voltage at the terminals, this can be done by slightly turning the potentiometer knob.

On the image figure 5 an electrode with a Wollaston wire is shown, and on figure 6 shows how to connect the detector to a battery and a potentiometer.

Carboride detector

The carborundum detector is very simple to manufacture, its design consists of a small carborundum crystal placed between two copper springs. It works because silicon carbide has a property called one-sided conduction. Assume that a carborundum crystal is connected in series with a battery and a galvanometer, measure the amount of current flowing through the circuit, now reverse the polarity of the battery connection and measure the current again. We will find that the magnitude of the current in both measurements is very different, although the EMF of the battery remains unchanged. This shows that for currents flowing in one direction, carborundum has a very high resistance and is practically an insulator, and for currents flowing in the opposite direction, carborundum is a relatively good conductor. Therefore, a carborundum crystal can act as a rectifier and convert fluctuations or alternating current into direct current. In addition to carborane, many crystals have the properties of one-way conduction, although less pronounced.

It has also been found that at some voltages the one-way conductance of the crystal is greater than at others, and in practice this is achieved by applying battery voltage to the crystal through a potentiometer. This detector is quite sensitive and reliable and is widely used in the United States of America.

Fleming's lamp

Rice. 7. Fleming's lamp and its inclusion in the circuit.

The Fleming lamp detector consists of a lamp with a carbon or tungsten filament, a metal plate is placed in the lamp bulb, isolated from the filament, and connected to a conductor, the output of which passes through the glass wall of the lamp to the outside and is the third electrode. If an incandescent filament is heated by connecting a suitable battery to its terminals, then the space between the filament and the insulated plate will have one-sided conductivity, and if the lamp is now included in a circuit in which alternating current is present, then due to the rectifying properties of the lamp, alternating current will be converted into a unidirectional current that can be heard in the handset. The rectifier lamp is shown in figure 7, the same figure also shows a way to turn on the lamp in the circuit.

If the contact point between two dissimilar metals included in a closed circuit is heated, then a current will appear in the circuit. For example, let's take a piece of bismuth and a little antimony, connect them together and connect a suitable galvanometer to their free ends, and we will see that if the contact point is heated to a higher temperature than the rest of the circuit, then the current will flow from bismuth towards antimony, the amount of current will be proportional to the temperature difference between the hot and cold parts of the connection. Almost any textbook on electrical engineering has a table showing the thermoelectric series of metals and their thermoelectric potentials or EMF per degree Celsius when paired with lead. For example, suppose we created a tellurium-lead pair and heated it 1 degree Celsius above the cold part of the circuit, an emf of about 500 microvolts would appear.

Some of the metal sulfides, such as galena, have been found to have very significant thermoelectric properties, and therefore galena is usually one of the elements of a thermocouple used as a detector for wireless telegraphy.

Rice. 8. Thermoelectric detector.

Two very effective combinations are galena-graphite or galena-tellurium, both of which are highly sensitive. The design of such a detector is shown in figure 8. The galena crystal is soldered to the holder with Wood's alloy (this metal melts in boiling water), graphite can be taken from any fairly hard pencil, and replaceable pencil leads for sale are very convenient.

The pressure is adjusted with a small screw. Being a current device, in the circuit the thermojunction is connected in series with the capacitor, and in the presence of high-frequency oscillations in the circuit, the thermojunction heats up and as a result a small potential difference is formed, which charges the capacitor, which is then discharged through the headphones.

With a good galena crystal, the detector works very stably, but the passage of strong atmospheric interference sometimes breaks it, apparently this detector behaves like a coherer and the electrode surfaces are slightly welded together. If the graphite-galena contact is temporarily disconnected and then returned to its previous position, then the detector sensitivity is fully restored.

Magnetic detector

The Marconi magnetic detector consists of an endless tape containing 70 strands of #40 (0.08 mm) iron wire covered with silk. The tape passes through two pulleys, which are driven by a clockwork, and at some point each point of the tape passes through a glass tube, on which is wound a copper wire No. 36 (0.13 mm) in silk insulation, the length of the winding is about two centimeters. This is the primary winding, terminals are connected to its ends. Above this winding is placed a coil with a secondary winding, wound with the same wire, the resistance of the winding is 140 ohms, the ends of the winding are connected to the terminals to which the headphones are connected. Above the coils are placed two horseshoe-shaped magnets with the same poles located side by side, as shown in Fig. Figure 9-1. The principle of operation of the detector is based on the fact that electrical oscillations can affect the magnetic hysteresis of iron. Figure 9-2, perhaps, will help to understand the principle of operation of the detector. Suppose that a piece of soft iron from an AC transformer is magnetized by a force H, which first increases to a maximum, then drops to zero, then reaches a negative maximum and again decreases to zero, we will find that if on one axis of the graph we plot the magnitude of the magnetizing force H , and on the other axis - the density of field lines B, then the curve will take the form shown in rice. 9. Starting from zero, if the magnetizing force gradually increases to a maximum and if we note the flux density value for each increment of the magnetizing force, then we get a curve of 0, 1. If the force decreases to zero, then the curve will not return back to its original position, but will follow in the direction 1, 2, and if now the iron is subjected to the action of a magnetizing force of reverse polarity, then the curve will take position 2, 3, 4, 5. Thus, it is clear that the magnetic effect on iron, due to hysteresis, lags behind the magnetizing force, and that after magnetization, iron retains its magnetism for some time after the action of the magnetizing force. It is this lag that neutralizes the electrical oscillations passing through the primary winding.

Consider now the magnetic detector itself. A soft iron ribbon passing in front of the poles of two permanent magnets, and as each part of the tape passes in front of these poles, it becomes magnetized and, under the action of a clockwork, these magnetized parts move further. If now the electrical oscillations pass through the primary winding, then the hysteresis of the tape will disappear and that magnetized part of the tape that has left the field of the magnet will be demagnetized and the lines of force will be redistributed through the second winding, which will lead to the appearance of current in it, and since the headphones are connected to the secondary winding, then this current will flow in them, which can be heard.

On Figure 10 the Marconi apparatus is shown, it can be seen that there are two sets of coils and magnets, and the clockwork and the movable metal band are common to them. In the event of a detector failure on one side, it will be easy to switch to the other side. On the left side of the device there is a winding key and a key to turn it on or off, the adjusting screw on the top right is for adjusting the tension of the movable iron band.

Rice. 10. Marconi magnetic detector (with cover removed) and telephone capacitor

On Figure 11 the detector circuit is shown and the magnets are shown in the position of the greatest sensitivity, that is, with the same poles to each other. Although the system is very sensitive in this position, the noise sometimes heard in telephones is very disturbing when receiving weak signals.

This drawback can be overcome by placing magnets as shown in figure 12, while the magnets are located opposite poles to each other, and in addition, the edge of one of the magnets is slightly higher than the edge of the other by moving the magnet away from the tape, the best position is found experimentally. The magnets used in this detector are brightly polished on one side and blackened on the other. When both polished or blackened sides are in front, the magnets will be turned towards each other with the same poles, when there is one polished and one blackened side in front, then the magnets will be located to each other with opposite poles. The practical use of this detector has proven its high reliability. It also has good sensitivity and requires little to no maintenance other than occasional re-winding. It was Marconi's magnetic detector that was installed on the sunken Titanic.

handsets

Handsets for receiving wireless messages are essentially the same as conventional commercial handsets. The difference is only in minor design details. As you know, the telephone handset mainly consists of a permanent horseshoe magnet, on the poles of which there is an extension of soft iron, on which are installed coils with windings of insulated copper wire, these two coils are connected in series, and the ends of the windings are connected to the terminals. Directly in front of the poles, close to them, is a flexible disk (membrane) made of soft iron, fixed rigidly at the edges. On figure 13 construction is clearly shown. Two such handsets, connected in series and attached to a connecting arc, form headphones (headphones). Phones are typically used in high-resistance detector circuits, their efficiency depends on ampere turns, their windings typically have a much higher resistance than conventional commercial phones, the winding resistance can range from 500 ohms to 5 k ohms and depends on the type of schema in which they will be used. Since it would be impossible to obtain the required number of turns in the small space of the coils with copper wire in silk or paper insulation, the coils are wound with copper enameled wire, which takes up much less space.

Rice. 13. Handset device.

Handsets are recognized as one of the most sensitive devices ever invented for detecting the presence of electric current, their sensitivity can be judged by the fact that an intermittent current of only a few microamperes produces an easily audible sound in the handsets. The loudness of the sound, however, depends not only on the magnitude of the current, but also on its frequency. The handset has been found to have maximum sensitivity at frequencies between 600 and 1000 Hz. This is undoubtedly due to the fact that the natural frequency of the membrane is about the same order, and also, perhaps, the fact that the human ear best perceives sounds lying at these frequencies plays a role.

At the beginning of this year, I began to reproduce some experiments ... on electrical vibrations with the aim of using them in lectures, but the very first attempts showed me that the phenomenon underlying these experiments - the change in the resistance of metal filings under the influence of electrical vibrations - is rather unstable ; to master the phenomenon, I had to try several combinations. As a result, I came up with the design of an instrument that serves for objective observations of electrical oscillations, suitable both for lecture purposes and for recording electrical perturbations occurring in the atmosphere ...

In 1891, Branly discovered that ... metal powders have the ability to instantly change their resistance to electric current if an electrophore machine or an induction coil is discharged near them ...

Mechanical shocks return the sawdust again to its previous state, characterized by high resistance. The action of the discharge can again reduce it, and again by shaking it is possible to obtain the previous resistance values ...

First of all, I wanted to give such a form to the device with sawdust, in order to have the possible constancy of sensitivity ...

The most successful form in terms of significant sensitivity, with sufficient constancy, is made as follows. Inside the glass tube, on its walls, two strips of thin sheet platinum AB and CD are glued almost along the entire length of the tube (Fig. 1). One strip is brought out to the outer surface from one end of the tube, the other - from the opposite end. Strips of platinum with their edges lie at a distance of about 2 mm with a width of 8 mm; the inner ends of the strips B and C do not reach the stoppers that close the tube, so that the powder placed in it cannot, crowding under the stopper, form conductive threads that are indestructible by shock, as happened in some models. The length of the entire tube is sufficient at 6-8 cm with a diameter of about 1 cm...

The tube during its action is horizontal, so that the strips lie in its lower half and the metal powder completely covers them. However, the best effect is obtained if the tube is not more than half full.

In all experiments, both the value and the constancy of sensitivity are affected by the size of the grains of the metal powder and its substance. Best Results obtained by using iron powder ...

The diagram (Fig. 2) shows the location of the parts of the device. The sawdust tube is suspended horizontally between clamps M and N on a light clock spring, which, for greater elasticity, is bent on the side of one clamp in a zigzag pattern. A bell is located above the tube so that during its action it can give light blows with a hammer in the middle of the tube, protected from breaking by a rubber ring. It is most convenient to fix the handset and the bell on a common vertical plank. The relay can be placed anywhere.

The device operates as follows. A battery current of 4-5 V constantly circulates from terminal P and platinum plate A, then through the powder contained in the tube to another plate B and through the coil of the relay electromagnet back to the battery. The strength of this current is not sufficient to attract the armature of the relay, but if the tube AB is subjected to the action of an electrical oscillation, then the resistance will instantly decrease, and the current will increase so much that the armature of the relay will be attracted. At this moment, the circuit from the battery to the bell, interrupted at point C, will close, and the bell will begin to operate, but immediately the shaking of the tube will again reduce its conductivity, and the relay will open the bell circuit. In my device, the resistance of sawdust after strong shaking is about 100,000 ohms, and the relay, having a resistance of about 250 ohms, attracts an armature at currents from 5 to 10 mA (adjustment limits), that is, when the resistance of the entire circuit drops below a thousand ohms. The device responds to a single oscillation with a short ring; continuously operating discharges of the spiral respond quite often, at approximately equal intervals, with the following calls ...

The device ... can be used for various lecture experiments with electrical vibrations ...

Another application of the instrument, which may give more interesting results, would be its ability to detect electrical vibrations occurring in a conductor associated with point A or B (in the diagram), when this conductor is subjected to electromagnetic perturbations occurring in the atmosphere. To do this, it is enough to connect the device, protected from any other actions, with an overhead wire laid far from telegraphs and telephones, or with a lightning rod. Any oscillation that goes beyond a certain limit in its intensity can be noted by the device and even registered, since any closing of the relay contact in the diagram at point C can activate, in addition to the bell, an electromagnetic marker. To do this, it is enough to connect one end of its winding between points C and D, and the other to the battery terminal P, i.e., connect the electromagnet in the circuit parallel to the bell ... In conclusion, I can express the hope that my device, with its further improvement, can be applied to the transmission of signals over distances by means of fast electrical oscillations, as soon as a source of such oscillations with sufficient energy is found.

Kronstadt, December 1895

M. A. Brazhnikov,
, GOU gymnasium No. 625, Moscow

From the history of the creation of radio

Works by A.S. Popova

On April 25 (May 7), 1895, Popov made a report at a meeting of the Physics Department of the Russian Physico-Chemical Society "On the relationship of metal powders to electrical vibrations". The minutes of the meeting noted: “Based on the experiments of Branly<...>[And. - Ed.] using the high sensitivity of metal powders to very weak electrical vibrations, the speaker built an instrument designed to show fast fluctuations in atmospheric electricity. The device consists of a glass tube filled with metal powder and inserted into a sensitive relay circuit. The relay closes the current of the battery, which activates the electric bell, located so that its hammer strikes both the cup of the bell and the glass tube. When the device is in the field of electrical oscillations or connected to a conductor that is in their sphere of action, the resistance of the powder decreases, the relay closes the battery current and activates the bell; already the first blows of the bell on the tube restore the previous high resistance of the powder and, consequently, bring the device to its former state, sensitive to electrical vibrations. Preliminary experiments carried out by the speaker with the help of a small telephone line in the city of Kronstadt showed that air is indeed sometimes subject to rapid changes in its potential. The main experiments on changing the resistance of powders under the influence of electrical vibrations and the described device were shown by the speaker. (See Table 3 below.)

In January 1896, in the article "A device for detecting and recording electrical oscillations", a diagram of the device was given and its operation was described. Compared with the report, the article was supplemented with a description of "another application of the device", namely the second receiver, equipped with a recorder and "suitable for recording electrical perturbations occurring in the atmosphere" (later this device was called lightning detector). In the article by A.S. Popov points out that O. Lodge's publication prompted him to start direct research. However, he used a different type of coherer and also came up with original way automatic decohering under the influence of an incoming radio wave. The lightning detector received discharges at a distance of tens of kilometers. These devices were reliable: the lightning detector worked at the Forestry Institute for several years. The hypothetical idea of telegraphy without wires was becoming a reality.

Thus, A.S. Popov in 1895 was the first: he showed the fundamental possibility of receiving signals at a considerable distance; created devices for practical purposes with the reception of waves through a grounded antenna (open oscillatory circuit) and with signal detection and restoration of the coherer sensitivity using the energy of the incoming wave. (As the inventor himself noted in his aforementioned article in January 1896, “the device responds to a single oscillation with a short ring; continuously acting discharges of the spiral respond quite often, at approximately equal intervals with the following calls.” Thus, it is important to emphasize that the first system A .S. Popov, like all his subsequent systems, was suitable for transmitting and receiving short (dots) and long (dash) signals without wires, which allowed them to be used for transmitting and receiving messages in Morse code. - Ed.)

Transmitter. Into the primary winding of a Ruhmkorff coil IN 0 turned on the mechanical interrupter I driven by an electric motor. The key was included in the same circuit M- manipulator original design, which allowed the circuit to be closed manually: a spring-loaded metal needle was lowered into a cup of mercury by pressing the hand. Paraffin oil was poured over the mercury, which made it possible to avoid sparks and, consequently, the rapid oxidation of the contact. When the primary circuit was closed, the secondary winding was excited, and a spark breakdown occurred between the poles of the arrester. damped high-frequency oscillations led to the emission of a train of electromagnetic waves by a grounded antenna. The wavelength was determined by the length of the antenna.

Receiver. An inductor with two probes was introduced into the receiving grounded antenna circuit, which made it possible to tune the receiving circuit to the resonant frequency. The high-frequency coherer circuit consisted of an inductor, the coherer itself and a capacitor - in the form of two Leyden jars. With the passage of a high-frequency signal, the coherer closed the relay circuit, which included the electromagnet of the Morse apparatus in the local battery circuit M and at the same time a hammer shaker. The armature of the electromagnet of the Morse apparatus closed the relay R′, which included a second local battery that powered the electromagnet. The latter “stopped” the Morse clockwork, which made it possible to automatically receive telegrams, which was also announced by a call S included in the relay circuit R.

On March 12/24, 1896, at a meeting of the Russian Physical Society, Popov demonstrated the reception of a telegram using his receiver (the antenna was copper wire with a diameter of 1.5–2 mm, released through window frame outside and suspended from the roof of the building, from which it was isolated by porcelain rings). According to the memoirs of the meeting participants V.K. Lebedinsky, O.D. Khvolson and V.V. Skobeltsyn, the words "Heinrich Hertz" were transmitted in German transcription ( Heinrich Hertz . – Ed.] and recorded by the Morse apparatus. Prof. Khvolson wrote: “I attended this meeting and clearly remember all the details. The departure station was located at the Chemical Institute of the University, the receiving station was in the auditorium of the old physics room. The distance is approximately 250 m. The transmission took place in such a way that the letters were transmitted in Morse alphabet, and the characters were clearly audible. At the blackboard stood the chairman of the Physical Society, prof. F.F. Petrushevsky, holding paper with the key to the Morse alphabet and a piece of chalk. After each transmitted sign, he looked at the paper and then wrote down the corresponding letter on the board. Gradually, the words “ Heinrich Hertz» and besides with Latin letters. It is difficult to describe the delight of the many present and the applause of A.S. Popov when these two words were written. It should be added that P.N. was behind the transmitting apparatus. Rybkin. The meeting was public, but a detailed report on them was not published, because the work was taken under the control of the military department.

If 1895–1996 can rightfully be called the years of the birth of radio communications all over the world: in Russia, England, Germany, France, then the next five years - years of practical development of wireless telegraphy.

Summer 1896 A.S. Popov conducted the first experiments on the Rybka steam boat.

Summer 1896 A.S. Popov, for which he was awarded the Diploma of the 2nd category.

In May 1897 A.S. Popov conducts experiments on the reception and transmission of radio signals on the Rybka boat in the Kronstadt harbor, the range was 640 m. In the summer, he was forced to leave to work at the power plant at the Nizhny Novgorod fair, leaving a detailed action plan to P.N. Rybkin. Among the tasks set were: “1. Increase the distance to which signals can be sent<…>3. Determine the degree of constancy of the sensitivity of devices<…>4. Determine the influence of atmospheric conditions<…>5. Test the operation of devices in a ship environment<…>» . All experiments on the Transund roadstead in the Vyborg Bay were carried out by P.N. Rybkin, while in correspondence with A.S. Popov. The transmitter was installed on the pier of Teykar-Sari island. The receiving station was placed on a steam boat. It consisted of a receiving wire about 9 m long, suspended on a mast 24 feet (≈ 7.3 m), a sensitive tube inserted into a circuit of two elements, and a Carpentier voltmeter. According to the deviation of the voltmeter needle, the signals sent by the sending station were detected. The grounding was a zinc sheet, lowered into the water. Later, the receiving station was transferred to the cruiser "Afrika". The experiments were completed by the installation of a telegraph communication between the training ship "Europe" and the cruiser "Afrika". Tests under these conditions established the longest range of about 3 km. The work carried out allowed us to draw important conclusions: “1. Thunderclouds and even clouds, giving electrical discharges, serve as sources of EMW, which can cause the action of the receiving device in addition to sending, and with frequent discharges during a thunderstorm, telegraphy is impossible.<...>2. Humidity of the atmosphere has an adverse effect on the insulation of the vibrator and weakens the discharge, but this effect can be easily eliminated by the device of closed devices.<...>3. It was very important to decide whether the state of the atmosphere affects the propagation of radio waves; for this, experiments were made during heavy rain and very light rain - no weakening effect was noticed. There was no fog during the experiments<...> ).

In 1898 the range of reliable reception increased to 5.5 km between ships and 11 km between the coast station and the cruiser "Afrika".

In 1899 It was discovered the possibility of receiving wireless telegraph signals by ear - in headphones. This simplified the reception scheme and increased the communication range. On June 11, signals were received at a distance of 36 km between Fort Konstantin and the village of Lebyazhye.

On the left - the cruiser "General-Admiral Apraksin" on the rocks near about. Gogland, 1899–1900
On the right - a memorial stele in honor of the establishment on January 24, 1900 of the first radio communication line between about. Gogland and about. Kutsalo
(URL: http://www.qrz.ru)

The event was the accident of the battleship General-Admiral Apraksin, which ran aground near about. Gogland in November 1899. Reliable and fast communication was necessary for carrying out rescue operations. However, the island was located in the middle of the Gulf of Finland, and the laying of a telegraph wire in winter time didn't seem possible. Exactly these difficult conditions demonstrated the virtues of radio. From the beginning of February to April 1900 between Gogland and Kotka, the world's first radio communication line operated, which was not experimental, like Marconi's (he achieved stable transmission across the English Channel in the summer of 1899), but practical. She played an important role not only in the successful completion of rescue operations. February 6 (N.S.) A.S. Popov transmitted a radiogram from the head of the main naval headquarters, Vice Admiral F.K. Avelana to the commander of the icebreaker "Ermak", which was accepted by P.N. Rybkin. The record of the hardware log of the Gogland station reads: “January 24, 9 a.m. Gogland from St. Petersburg to the commander of the Icebreaker Yermak Near Lavensari, an ice floe with fifty fishermen was torn off. Immediately assist in the rescue of these people. One hundred and eighty-six Avelans. A photocopy of this page is presented in Table. 3. Icebreaker "Ermak", which was at that time at about. Gogland, went in search of the sea and took off the fishermen. Popov informed the commandant of Kronstadt S.O. Makarov, who, in turn, informed the Minister of Finance S.Yu. Witte: “The inventor of telegraphy without wires, Popov, telegraphed me from the island of Kutsalo that he had received a telegram without wires with the following content: “The front stone has been removed. Yermak left at four o'clock in the morning for the fishermen who had been carried away on an ice floe from Lavensari Island. On the same day, S.O. Makarov congratulated A.S. Popov by telegraph: “Kotka. Popov. On behalf of the sailors of Kronstadt, I cordially greet you on the brilliant success of your invention. The opening of a wireless telegraph communication from Kutsalo to Gogland at a distance of 43 miles is biggest scientific victory» . Has begun new stage development of radio in Russia. Vice Admiral I.M. Dikov reported in a report to the head of the Naval Ministry, Admiral P.P. Tyrtov: "With the establishment of communication by wireless telegraph between Gogland and Kutsalo<...>we can consider experiments with this method of signaling completed, and the Marine Technical Committee believes that the time has come to introduce wireless telegraphy on the ships of our fleet<...>» .

In 1898 the production of A.S. Popov, first by the Ducrete firm in Paris, and then by the Kronstadt radio workshop. A significant achievement was the development of a telephone receiver based on the coherer detector effect, which made it possible to increase the communication range to 40 km. Subsequently, Popov received a patent for it in Russia, England and France. Already in 1900, these devices were found practical use, and since 1904 they were manufactured by the St. Petersburg branch of Siemens and Halske and the German company Telefunken.

In the designs of transmitters and receivers 1897-1901. the technical ideas implemented in the first receiver continue to develop, tuning for resonance appears, and antennas become more complex. A.S.'s predictions come true. Popova: “I can express the hope that my device, with further improvement, can be applied to the transmission of signals over distances using fast electrical oscillations, as soon as a source of such oscillations with sufficient energy is found.” In 1899, the Kronstadt workshop produced an induction coil with a spark length of 80 cm! An even greater increase in the radiated power gave an increase in the frequency of interruption of the current supplying the induction coil (the number of discharges per second increased), see table. 3.

A.S. Popov
(1859 – 1905/1906)

Radio receiver, 1895

Discharger, 1895

Radio receiver with Morse apparatus, 1896

Thundercatcher, 1896

Medal of the World Exhibition in Paris, 1900

Reception station 1899, workshop Kolbasiev

Telephone radio receiver, 1902

Hardware log page of the Gogland station

Thunderstorm blueprint, performed by A.S. Popov, 1898

Popov-Ducrete receiver, 1901

LC a is the antenna input; TC a is the input of the earth; RR- access to the telegraph apparatus; Br is the Ducrete coherer; F- the key of the shaker chain (hammer); F a is the key of the coherer circuit; R– coherer circuit battery; P′ – closing circuit battery; R- a relay that closes the shaker circuit and the telegraph apparatus; Re, Re′ - shunts for the destruction of induction currents during opening (extra currents)

Receiver, 1895

Receiver, 1899

Transmission schemes

Near about. Gogland, 1900 (left) On the Black Sea, 1901 (right)

Receiver, 1897

A - antenna; B - battery; Bzv - kloopfer battery; B - Wenelt interrupter; Z - earth; Zv - ringing relay of the kloopfer; I - inductor; K - coherer; L - Leyden jars of variable capacity; L– inductive resistances; M - Morse apparatus; R– shunting non-inductive resistances; R - arrester; C - capacitor; T - telegraph key; Tr - transformer; Tl - telephone; U - Oudin resonator

Technical data

Schemes of 1895 and 1897 differ in the presence of resistances in the latter, perhaps inductive.

1895 With an antenna length of 2.5 m, signal reception at a distance of 60 m from the Hertz vibrator (with metal square sheets 40 cm). With a grounded antenna, the lightning discharge reception range is up to 30 km.

1897 With a mast height of 8 m, the maximum signal reception range is 5 versts (3 miles).

Description of receivers 1895–1897

The coherer is suspended on a light clock spring between points M, N; 100 kOhm (when an electromagnetic wave arrives, 1 kOhm);

AB– platinum contacts;

PQ– battery 4–5 V;

Relay 250 Ohm, actuation current 5–10 mA.

Anniversary ruble,
1983

Radio station on Koutsalo, 1900

The results of the experiments of A.S. Popov by radio reception range, 1897–1903.

Table 3. Devices and stations for receiving and transmitting A.S. Popov 1895–1903

Protocol 151 (201) of the meeting of the Physics Department of the Russian Physical and Chemical Society on April 25, 1895 // Invention of radio by A.S. Popov. S. 53.
Popov A.S. A device for detecting and registering electrical oscillations // Invention of radio A.S. Popov. pp. 55–64.
Kyandskaya-Popova E.G., Morozov I.D. On the issue of the world's first radiogram // Physics-PS. 2001. No. 12. (Publishing house "September 1".)
Kudryavtsev-Skaif S.A.S. Popov, inventor of the radio. Voenmorizdat, 1945. 259 p.
Golovin G.I. The inventor of radio - A.S. Popov. Molotov: Molotovgiz, 1948. 312 p.
Urvalov V.A. A.S. Popov is the inventor of the radio. // Physics-PS. 2006. No. 7. Electronic version of gas. "Physics". URL:
Monuments of science and technology in the museums of Russia / Ed. G.G. Grigoryan, V.A. Tsiryulnikov. M: State Polytechnic. museum. Moscow: Knowledge, 1992. 149 p.

Morozov I.D. A.S. Popov did not meet with G. Marconi and did not give him gifts // Physics-PS. 2003. No. 16, 17. What did A.S. Popov and what G. Marconi received a patent for // Physics-PS. 2002. No. 16, 20.
Radio electronics and communication. 1995. No. 1 (9). (The anniversary issue “Dedicated to the 100th anniversary of the invention of radio by A.S. Popov.”)
Severinova V.P., Urvalov V.A. The first award winners prof. A.S. Popova // Physics-PS. 2008. No. 8.
Urvalov V.A. A.S. Popov - the inventor of radio // Physics-PS. 2006. No. 8. Conquest of the ether // Physics-PS. 2001. No. 17.
Fedotov E.A. The introduction of radio communication in the Black Sea Fleet and in Sevastopol // Physics-PS. 2007. No. 7. Comparing the schemes of O. Lodge, A.S. Popova, G. Marconi // Physics-PS. 2001. No. 4.
Shmyrev A.A. The invention of radio by A.S. Popov // Physics-PS. 2008. No. 7.

Equipment for the wireless transmission of electrical signals of various durations (i.e. radio communications. - Ed.) consisted of a transmitter (as part of a Ruhmkorff coil with a key in the power circuit, a spark gap and a vibrator in the form of two metal sheets 40 × 40 cm) and a receiver with an antenna (vertical wire 2.5 m high), the circuit of which included a coherer and a telegraph relay , with the help of which an electric bell was connected, providing a sound indication of the received signals and restoring the sensitivity of the coherer by mechanical action on it after each signal. - Author's edit.

The telegraph tape was kept by V.K. Lebedinsky, but died during the capture of Riga by the Germans in 1918.

Only one phrase was recorded in the protocol:

“A.S. Popov shows devices for a lecture demonstration of Hertz's experiments. Therefore, the priority of A.S. Popov had to prove to the rest of the world after the fact; but it is to this date that O.D. Khwolson the birth of radio communications.

Marconi came to similar conclusions as a result of experiments near the English Channel and the US coast in the summer and autumn of 1899. “It was reliably established (possibility. - M.B.) applications for signaling (by Marconi wireless telegraphy apparatuses. – M.B.) between the ships of the squadron in rain, fog and darkness. Wind, rain, fog and more weather do not affect transmission; however, moisture can reduce the range, speed and accuracy of transmission due to deterioration of the insulation of the overhead wire and appliances. Darkness has no effect." With an antenna height of 45 m, the receiving range reached 30–40 km.

">From an article by A.S. Popova
"Instrument for detecting and registering
electrical oscillations"

"> The content of this article in its main part was the subject of communication in the April meeting of the Physics Department of our society ...

">At the beginning of this year, I began to reproduce some experiments ... on electrical vibrations with the aim of using them in lectures, but the very first attempts showed me that the phenomenon underlying these experiments - the change in the resistance of metal filings under the influence of electrical vibrations - is rather unstable ; to master the phenomenon, I had to try several combinations.As a result, I came up with the design of an instrument that serves for objective observations of electrical oscillations, suitable both for lecture purposes and for recording electrical perturbations occurring in the atmosphere ...

">In 1891, Branly discovered that ... metal powdershave the ability to instantly change their resistance to electric current if a discharge of an electrophore machine or an induction coil occurs near them ...

">Mechanical shocks return the sawdust again to its previous state, characterized by high resistance. The action of the discharge can again reduce it, and again by shaking it is possible to obtain the previous resistance values ...

">Before all I wished was to give such a form to the device with sawdust, in order to have the possible constancy of sensitivity ...

">The most successful form in terms of significant sensitivity, with sufficient constancy, is made as follows. Inside the glass tube, on its walls, two strips of thin sheet platinum AB are glued and CD almost the entire length of the tube (Fig. 1). One strip is brought to the outer surface from one end of the tube, the other - from the opposite end. Strips of platinum with their edges lie at a distance of about 2 mm with a width of 8 mm; the inner ends of the strips B and C do not reach the stoppers that close the tube, so that the powder placed in it cannot, crowding under the stopper, form conductive threads that are indestructible by shock, as happened in some models. The length of the entire tube is sufficient at 6-8 cm with a diameter of about 1 cm...

">The tube during its action is horizontal, so that the strips lie in its lower half and the metal powder completely covers them. However, the best effect is obtained if the tube is not more than half full.

"> In all experiments, both the value and the constancy of sensitivity are affected by the size of the grains of the metal powder and its substance. The best results are obtained by using iron powder...

">The diagram (Fig. 2) shows the location of the parts of the device. The sawdust tube is suspended horizontally between clamps M and N on a light clock spring, which, for greater elasticity, is bent on the side of one clamp in a zigzag pattern. A bell is located above the tube so that during its action it can give light blows with a hammer in the middle of the tube, protected from breaking by a rubber ring. It is most convenient to fix the handset and the bell on a common vertical plank. The relay can be placed anywhere.

"> The device operates as follows. A battery current of 4-5 V constantly circulates from the P terminal and the platinum plate. A, then through the powder contained in the tube to another plate B and along the relay electromagnet winding back to the battery. The strength of this current is not sufficient to attract the armature of the relay, but if the tube AB is subjected to the action of an electrical oscillation, then the resistance will instantly decrease, and the current will increase so much that the armature of the relay will be attracted. At this moment, the circuit from the battery to the bell, interrupted at point C, will close, and the bell will begin to operate, but immediately the shaking of the tube will again reduce its conductivity, and the relay will open the bell circuit. In my device, the resistance of sawdust after strong shaking is about 100,000 ohms, and the relay, having a resistance of about 250 ohms, attracts an armature at currents from 5 to 10 mA (adjustment limits), that is, when the resistance of the entire circuit drops below a thousand ohms. The device responds to a single oscillation with a short ring; continuously operating discharges of the spiral respond quite often, at approximately equal intervals, with the following calls ...

">The device ... can be used for various lecture experiments with electrical vibrations ...

">Another application of the instrument, which may give more interesting results, would be its ability to detect electrical vibrations occurring in a conductor connected to a point. A or B (in the diagram), in the case when this conductor is subjected to the action of electromagnetic perturbations occurring in the atmosphere. To do this, it is enough to connect the device, protected from any other actions, with an overhead wire laid far from telegraphs and telephones, or with a lightning rod. Every hesitationpassing beyond a known limit in its intensity, can be noted by the device and even registered, since any closing of the relay contact on the circuit at the point WITH can actuate, in addition to the bell, also an electromagnetic marker. To do this, it is enough to connect one end of its winding between points C andD, and the other to the battery clamp R, i.e., include an electromagnet in the circuit parallel to the bell ... In conclusion, I can express the hope that my device, with further improvement, can be applied to the transmission of signals over distances using fast electrical oscillations, as soon as the source of such oscillations is found with sufficient energy.

Receiver device

He was not satisfied with the Hertz method, in which the vibration indicator was a small spark viewed through a magnifying glass, he was looking for a new, practical and sensitive vibration detector. So he designed a special mechanical radiometer, an air thermometer, but all these indicators did not satisfy Popov. Undoubtedly, at that time he was thinking about the practical application of the will of Hertz. Therefore, he perceived with particular acuteness everything new in the field of detecting electrical oscillations.

In 1890, the French physicist Edouard Branly reported on the effect he had observed of an electric discharge on the conductivity of metal powders (iron, aluminum, antimony, cadmium, zinc, bismuth, etc.). Branley wrote: If you make a circuit consisting of a Daniel element, a sensitive galvanometer, a metal conductor and an ebonite plate coated with copper or a tube with sawdust, then for the most part only an insignificant current passes. However, the resistance decreases sharply, as can be seen from the strong deviation of the galvanometer, if one or more discharges are made near the circuit.//M. A. Shatelen, Russian Electrical Engineering, p. 291.//

In 1894 Branly described this phenomenon in more detail in an article. However, neither the first nor the second communication emphasizes or even indicates the role of electrical oscillatory processes in the change in conductivity, and the question of using this phenomenon as an indicator of oscillations is not even raised.

As an indicator of fluctuations, a tube with sawdust was used by O. Lodge in 1894 and named by him. Lodge wrote. Lodge's message made a huge impression on Popov. His colleague P. N. Rybkin wrote about this: I still remember with what excitement A. S. showed me the issue of the magazine in which Lodge's article was placed, in which he described his famous experiments in applying Branly's discovery to the device of a coherer for detection by means of its electrical oscillations.

It is easy to understand both the excitement and further creative searches of Popov: a path has been outlined for solving a big problem. By the spring of 1895, the world's first receiver of electrical oscillations was created. On April 25 (May 7), 1895, at the 151st (201st) meeting of the Physics Department of the Russian Physical and Chemical Society, A. S. Popov made a report. The content of the report, supplemented by test reports on the registration of atmospheric discharges, carried out by G. A. Lobachevsky with Popov's device at the Forestry Institute in the summer of 1895, was the subject of Popov's article, presented in December 1895 in the journal of the Russian Physical and Chemical Society and appeared in the first issue of this journal for 1896. Popov's receiver is described by him in this article as follows:

The sawdust tube is suspended horizontally between clamps M and N on a light clock spring, which is bent in a zigzag pattern on the side of one clamp for greater elasticity. A bell is located above the tube so that during its action it can give light blows with a hammer in the middle of the tube, protected from breaking by a rubber ring. It is most convenient to fix the handset and the bell on a common vertical plank. The relay can be placed anywhere.

The device operates as follows. A battery current of 4-5 volts constantly circulates from terminal P to platinum plate A, then through the powder contained in the tube to another plate B, and through the coil of the relay electromagnet back to the battery. The strength of this current is not sufficient to attract the armature of the relay, but if the tube AB is subjected to the action of an electrical oscillation, then the resistance will instantly decrease and the current will increase so much that the armature of the relay will be attracted. At this moment, the circuit from the battery to the bell, interrupted at point C, will close and the bell will begin to operate, but the immediately shaken tube will again reduce its conductivity, and the relay will open the bell circuit.\\, USSR Academy of Sciences, 1945, p. 60.\\

Of the experiments cited by Popov to test the sensitivity of the receiver, the first two are especially important:
1) The device responds to electrophore discharges through a large audience, if parallel to the direction of the discharge, a wire about 1 meter long is drawn from point A or B to increase the energy reaching the sawdust.
2) In connection with a vertical wire 2.5 meters long, the device responded in the open air to vibrations produced by a large hertz vibrator (square sheets 40 centimeters aside) with a spark in oil, at a distance of 30 fathoms.

It is clear from the places we have highlighted in Popov's article that in 1895 he received radio waves at a distance of 60 m on the receiving antenna of his receiver. In the same article, Popov characterizes the scope of his device as follows: An apparatus with such a sensitivity can be used for various lecture experiments with electrical vibrations and, being closed in a metal case, can be conveniently adapted to experiments with electric rays ...
Another application of the instrument, which may give more interesting results, would be its ability to detect electrical vibrations occurring in a conductor associated with point A or B (in the diagram), when this conductor is subjected to electromagnetic perturbations occurring in the atmosphere. To do this, it is enough to connect the device, protected from any other actions, with an overhead wire laid far from telegraphs and telephones, or with a lightning rod. Before us is a clear picture of a shielded receiver that registers electromagnetic signals entering the receiving antenna. And the final conclusion of the author is quite natural: In conclusion, I can express the hope that my device, with further improvement, can be applied to the transmission of signals over distances by means of fast electrical oscillations, as soon as a source of such oscillations with sufficient energy is found..

Thus, A. S. Popov not only clearly represents the possibility of radiotelegraphy, but also indicates the way in which this problem can be solved: obtaining powerful signal transmitters. On March 12 (24), 1896, A. S. Popov demonstrated the world's first radio transmission and reception of a meaningful text from one building to another at a distance of about 250 m. , a radiogram was transmitted: . Acad. V. F. Mitkevich recalls this historic day in the following way: A memorable meeting took place on Sunday afternoon in a large auditorium of the old physical laboratory in the courtyard of St. Petersburg University. In this modest ordinary audience, a radio receiving station with a Morse apparatus was installed.

At a distance of 250 m, in the new building of the chemical laboratory of the university, there was a departure station fed by a Ruhmkorff coil. A. S. Popov’s closest assistant, P. N. Rybkin, was on duty near her.

Among those present at the meeting were representatives of the Maritime Department and the most prominent Russian electrical physicists of that time: O. D. Khvolson, I. I. Borgman, A. I. Sadovsky, V. K. Lebedinsky, M. A. Shatelen, A. L Gershun, G. A. Lyuboslavsky, Y. N. Georgievsky, N. A. Smirnov, V. V. Skobeltsyn, N. A. Bulgakov, N. G. Egorov, and F. F. Petrushevsky. Before the meeting, all those present got acquainted with the device of the radio receiving station, and then, seated on the student benches, they eagerly prepared for the experience of transmitting a telegram without wires.

The meeting was opened by the oldest physicist F. F. Petrushevsky, giving the floor to A. S. Popov. After a 30-40-minute report, the inventor sent one of the young people present to the departure station to P. N. Rybkin with instructions to start a radio broadcast.

The atmosphere in the physics laboratory became tense. All those assembled realized that they were present at the demonstration of an invention, the future of which even then seemed to be the greatest. The excitement of the meeting participants was increased by the fact that the text of the world's first telegram was known only to Popov and Rybkin. Keeping outward calmness, the inventor watched with a smile, with what intense attention all those present watched the letters slowly appearing on the tape of the Morse receiver, which Petrushevsky repeated with chalk on a large classroom board.

The transfer process is described in more detail by O. D. Khvolson. The transmission took place in such a way that the letters were transmitted in Morse alphabet and, moreover, the signs were clearly audible. At the blackboard stood the chairman of the Physical Society, prof. F. F. Petrushevsky, holding paper with the key to the Morse alphabet and a piece of chalk. After each transmitted sign, he looked at the paper and then wrote down the corresponding letter on the board. Gradually, the words Heinrich Hertz turned out on the board and, moreover, in Latin letters. It is difficult to describe the delight of the many present and the ovation to A. S. Popov when these two words were written.So one of the greatest inventions of the human genius began its life. The great inventor immortalized in the first radiogram the one who was the first in the world to observe electromagnetic waves. A. S. Popov was the first person to make these waves serve man.

Popov was in the service of the Naval War Department and had instructions not to disclose his discovery. Therefore, a record of the historical day, according to his instructions, was made in the protocols of the society in the following form: (ZHRFHO, 1896, vol. XXVIII, p. 124).

Literary sources:
A.I. Berg. M.I. Radovsky, "Inventor of radio A. S. Popov", Gosekergoizdat, 1950, p. 70
History of physics. Kudryavtsev P.S. - M:. Uchpedgiz. 1956. pp. 234-235.