Popov receiver diagram and designations. Simple radio receiver circuit: description

For a long time, radios topped the list of the most significant inventions of mankind. The first such devices have now been reconstructed and changed in a modern way, but little has changed in their assembly diagram - the same antenna, the same grounding and oscillatory circuit to filter out unnecessary signal. Undoubtedly, circuits have become much more complicated since the time of the creator of radio, Popov. His followers developed transistors and microcircuits to reproduce a higher quality and energy-consuming signal.

Why is it better to start with simple circuits?

If you understand the simple one, you can be sure that most of the path to success in the field of assembly and operation has already been mastered. In this article we will analyze several circuits of such devices, the history of their origin and the main characteristics: frequency, range, etc.

Historical reference

May 7, 1895 is considered the birthday of the radio receiver. On this day, the Russian scientist A.S. Popov demonstrated his apparatus at a meeting of the Russian Physicochemical Society.

In 1899, the first radio communication line, 45 km long, was built between and the city of Kotka. During World War I, direct amplification receivers and vacuum tubes became widespread. During hostilities, the presence of a radio turned out to be strategically necessary.

In 1918, simultaneously in France, Germany and the USA, scientists L. Levvy, L. Schottky and E. Armstrong developed the superheterodyne reception method, but due to weak electron tubes, this principle became widespread only in the 1930s.

Transistor devices emerged and developed in the 50s and 60s. The first widely used four-transistor radio, the Regency TR-1, was created by German physicist Herbert Mathare with the support of industrialist Jakob Michael. It went on sale in the US in 1954. All old radios used transistors.

Study and implementation began in the 70s integrated circuits. Receivers are now being developed through greater integration of nodes and digital signal processing.

Device characteristics

Both old and modern radios have certain characteristics:

1. Sensitivity is the ability to receive weak signals.
2. Dynamic range - measured in Hertz.
3. Noise immunity.
4. Selectivity (selectivity) - the ability to suppress extraneous signals.
5. Self-noise level.
6. Stability.

These characteristics do not change in new generations of receivers and determine their performance and ease of use.

The principle of operation of radio receivers

In the most general form, USSR radio receivers worked according to the following scheme:

1. Due to hesitation electromagnetic field appears in the antenna alternating current.
2. The oscillations are filtered (selectivity) to separate information from noise, i.e., the important component of the signal is isolated.
3. The received signal is converted into sound (in the case of radio receivers).

Using a similar principle, an image appears on a TV, digital data is transmitted, and radio-controlled equipment (children’s helicopters, cars) operates.

The first receiver was more like a glass tube with two electrodes and sawdust inside. The work was carried out according to the principle of the action of charges on metal powder. The receiver had a huge resistance by modern standards (up to 1000 Ohms) due to the fact that the sawdust had poor contact with each other, and part of the charge slipped into the air space, where it was dissipated. Over time, these filings were replaced by an oscillating circuit and transistors to store and transmit energy.

Depending on the individual circuit of the receiver, the signal in it may undergo additional filtering by amplitude and frequency, amplification, digitization for further software processing, etc. Simple scheme The radio receiver provides for single signal processing.

Terminology

An oscillating circuit in its simplest form is a coil and a capacitor closed in a circuit. With their help, you can select the one you need from all the incoming signals due to the circuit’s own frequency of oscillation. USSR radios, as well as modern devices, are based on this segment. How does it all work?

As a rule, radio receivers are powered by batteries, the number of which varies from 1 to 9. For transistor devices, 7D-0.1 and Krona type batteries with a voltage of up to 9 V are widely used. The more batteries a simple radio receiver circuit requires, the longer it will work .

Based on the frequency of received signals, devices are divided into the following types:

1. Long-wave (LW) - from 150 to 450 kHz (easily scattered in the ionosphere). What matters are ground waves, the intensity of which decreases with distance.
2. Medium wave (MV) - from 500 to 1500 kHz (easily scattered in the ionosphere during the day, but reflected at night). During daylight hours, the radius of action is determined by grounded waves, at night - by reflected ones.
3. Shortwave (HF) - from 3 to 30 MHz (do not land, are exclusively reflected by the ionosphere, so there is a radio silence zone around the receiver). With low transmitter power, short waves can travel long distances.
4. Ultrashortwave (UHF) - from 30 to 300 MHz (have a high penetrating ability, are usually reflected by the ionosphere and easily bend around obstacles).
5. - from 300 MHz to 3 GHz (used in cellular communications and Wi-Fi, operate within visual range, do not go around obstacles and propagate in a straight line).
6. Extremely high frequency (EHF) - from 3 to 30 GHz (used for satellite communications, are reflected from obstacles and operate within line of sight).
7. Hyper-high frequency (HHF) - from 30 GHz to 300 GHz (they do not bend around obstacles and are reflected like light, they are used extremely limited).

When using HF, MF and DV radio broadcasting can be carried out while being far from the station. The VHF band receives signals more specifically, but if a station only supports it, then you won’t be able to listen on other frequencies. The receiver can be equipped with a player for listening to music, a projector for displaying on remote surfaces, a clock and an alarm clock. The description of the radio receiver circuit with such additions will become more complicated.

The introduction of microcircuits into radio receivers made it possible to significantly increase the reception radius and frequency of signals. Their main advantage is relatively low energy consumption and small size, which is convenient for carrying. The microcircuit contains all the necessary parameters for downsampling the signal and making the output data easier to read. Digital processing signal dominates in modern devices. were intended only for transmitting an audio signal, only in recent decades the design of receivers has developed and become more complex.

Circuits of the simplest receivers

The circuit of the simplest radio receiver for assembling a house was developed back in Soviet times. Then, as now, devices were divided into detector, direct amplification, direct conversion, superheterodyne, reflex, regenerative and super-regenerative. Detector receivers are considered the simplest to understand and assemble, from which the development of radio can be considered to have begun at the beginning of the 20th century. The most difficult devices to build were those based on microcircuits and several transistors. However, once you understand one pattern, others will no longer pose a problem.

Simple detector receiver

The circuit of the simplest radio receiver contains two parts: a germanium diode (D8 and D9 are suitable) and main phone with high resistance (TON1 or TON2). Since there is no oscillatory circuit in the circuit, it will not be able to catch signals from a specific radio station broadcast in a given area, but it will cope with its main task.

For work you will need good antenna, which can be thrown onto a tree, and a ground wire. To be sure, it is enough to attach it to a massive piece of metal (for example, to a bucket) and bury it a few centimeters into the ground.

Option with oscillating circuit

To introduce selectivity, you can add an inductor and a capacitor to the previous circuit, creating an oscillating circuit. Now, if you wish, you can catch the signal of a specific radio station and even amplify it.

Tube regenerative shortwave receiver

Tube radio receivers, the circuit of which is quite simple, are made to receive signals from amateur stations on short distances- for ranges from VHF (ultra-short wave) to LW (long wave). Finger battery lamps work on this circuit. They generate best on VHF. And the resistance of the anode load is removed by low frequency. All details are shown in the diagram; only the coils and inductor can be considered homemade. If you want to take television signals, then coil L2 (EBF11) is made up of 7 turns with a diameter of 15 mm and a wire of 1.5 mm. 5 turns are suitable.

Direct amplification radio receiver with two transistors

The circuit also contains a two-stage low-frequency amplifier - this is a tunable input oscillatory circuit of the radio receiver. The first stage is an RF modulated signal detector. The inductor is wound in 80 turns with PEV-0.25 wire (from the sixth turn there is a tap from below according to the diagram) on a ferrite rod with a diameter of 10 mm and a length of 40.

This simple radio receiver circuit is designed to recognize powerful signals from nearby stations.

Supergenerative device for FM bands

The FM receiver, assembled according to E. Solodovnikov’s model, is easy to assemble, but has high sensitivity (up to 1 µV). Such devices are used for high-frequency signals (more than 1 MHz) with amplitude modulation. Thanks to the strong positive feedback the coefficient increases to infinity, and the circuit goes into generation mode. For this reason, self-excitation occurs. To avoid it and use the receiver as a high-frequency amplifier, set the coefficient level and, when it reaches this value, sharply reduce it to a minimum. For constant monitoring gain, you can use a sawtooth pulse generator, or you can do it simpler.

In practice, the amplifier itself often acts as a generator. Using filters (R6C7) that highlight signals low frequencies, the passage of ultrasonic vibrations to the input of the subsequent ULF cascade is limited. For FM signals 100-108 MHz, coil L1 is converted into a half-turn with a cross-section of 30 mm and a linear part of 20 mm with a wire diameter of 1 mm. And coil L2 contains 2-3 turns with a diameter of 15 mm and a wire with a cross-section of 0.7 mm inside a half-turn. Receiver amplification is possible for signals from 87.5 MHz.

Device on a chip

The HF radio receiver, whose circuit was developed in the 70s, is now considered the prototype of the Internet. Shortwave signals (3-30 MHz) travel great distances. It is not difficult to set up a receiver to listen to broadcasts in another country. For this, the prototype received the name world radio.

Simple HF receiver

A simpler radio receiver circuit lacks a microcircuit. Covers the range from 4 to 13 MHz in frequency and up to 75 meters in length. Power supply - 9 V from the Krona battery. The installation wire can serve as an antenna. The receiver works with headphones from the player. The high-frequency treatise is built on transistors VT1 and VT2. Due to capacitor C3, a positive reverse charge arises, regulated by resistor R5.

Modern radios

Modern devices are very similar to radio receivers in the USSR: they use the same antenna, which produces weak electromagnetic oscillations. High-frequency vibrations from different radio stations appear in the antenna. They are not used directly to transmit a signal, but carry out the operation of the subsequent circuit. Now this effect is achieved using semiconductor devices.

Receivers were widely developed in the middle of the 20th century and have been continuously improved since then, despite their replacement mobile phones, tablets and TVs.

The general design of radio receivers has changed slightly since Popov's time. We can say that the circuits have become much more complicated, microcircuits and transistors have been added, and it has become possible to receive not only an audio signal, but also to build in a projector. This is how receivers evolved into televisions. Now, if you wish, you can build whatever your heart desires into the device.

Radio is one of the most significant achievements of the human mind of the late 19th century. And the beginning of the development of radio technology is inextricably linked with the name of Alexander Stepanovich Popov, who in Russia is considered the inventor of radio. Today marks the 150th anniversary of his birth.

Russian scientist Alexander Popov was born in the village of Turinsky Mines, now the city of Krasnoturinsk, Sverdlovsk Region, in the family of priest Stepan Petrov Popov and his wife Anna Stepanovna.

He studied at Dalmatovsky and then Yekaterinburg theological schools. In 1877 he graduated with honors from general education classes at the Perm Theological Seminary. After that, he entered the Faculty of Physics and Mathematics of St. Petersburg University. While studying at the university, he was an assistant at lectures on physics, worked as a guide at the First Electrical Engineering Exhibition in St. Petersburg, and in 1881-1883 he worked as a power plant fitter in the Electrical Engineer partnership.

In 1882 he defended his dissertation “On the principles of magneto- and dynamo-electric machines.” direct current" and received the academic degree of Candidate of Sciences. The following year, the academic council of the university decided to leave him at the university to prepare for the professorship.

Alexander Stepanovich was also involved in teaching activities, in particular, he lectured and conducted practical lessons in Kronstadt in the Mine Officer Class (MOC) of the Naval Department.

In April 1887, Popov was elected a member of the Russian Physico-Chemical Society (RFCS), and in 1893 he joined the Russian Technical Society (RTO).

He traveled a lot - not only in Russia. So, in the same 1893 he was at the World Industrial Exhibition in Chicago (USA). He visited Berlin, London and Paris, where he became acquainted with the activities of scientific institutions.

Starting point

The main milestone in Popov’s activities was his creation of a radio receiver and radio communication system. In 1895, he manufactured a coherent receiver capable of receiving electromagnetic signals of varying durations at a distance without wires. He assembled and tested the world's first practical radio communication system, including a Hertz spark transmitter of his own design and a receiver invented by him. During the experiments, the ability of the receiver to register electromagnetic signals of atmospheric origin was also discovered.

In the same year, Popov spoke at a meeting of the Russian Federal Chemical Society with a report “On the relationship of metal powders to electrical vibrations,” during which he demonstrated the operation of the equipment wireless communication. Five days later, the first report about successful experiences Popov with devices for wireless communication.

In 1898 it began industrial production Popov's ship radios by E. Ducretet in Paris. Created on the initiative of the scientist, the Kronstadt radio workshop, the first radio engineering enterprise in Russia, began producing equipment for the Navy in 1901. In 1904, the St. Petersburg company Siemens and Halske, the German company Telefunken and Popov jointly organized the “Department of Wireless Telegraphy according to the A. S. Popov System.”

In 1901, Alexander Stepanovich Popov became a professor of physics at the Electrotechnical Institute of Emperor Alexander III. In 1905, by decision of the Academic Council, he became the first elected director of the institute.

In general, it should be noted that Popov’s work as a scientist and inventor was highly appreciated both in Russia and abroad during his lifetime. He was awarded the RTO Prize, the Highest Award "for continuous work on the use of telegraphy without wires on naval vessels", he was awarded the Grand Gold Medal of the World Industrial Exhibition in Paris (1900), the Order of the Russian Empire, was elected an honorary member of the RTO, an honorary engineer - electrician and president of RFHO.

After his death on January 13, 1906, a foundation was created in Russia and a prize was established in his name. In 1945, a holiday was established - Radio Day, celebrated on May 7, the "Honorary Radio Operator" badge and the Gold Medal of the USSR Academy of Sciences named after A. S. Popov, personal prizes and scholarships were established. Also named after Popov is a minor planet, an object of the lunar landscape reverse side Luna, Central Museum of Communications and street in St. Petersburg, Research Institute of Radio Reception and Acoustics, motor ship. Monuments were erected to him in St. Petersburg, Yekaterinburg, Krasnoturinsk, Kotka (Finland), Petrodvorets, Kronstadt, and on the island of Gogland.

And in 2005, the International Institute of Electrical and Electronics Engineers (IEEE) installed a memorial plaque at the St. Petersburg State Electrotechnical University "LETI" in memory of the invention of radio by Popov. Thus, with international public recognition, the organization confirmed the priority of Alexander Stepanovich Popov in the invention of radio.

However, the question of who actually invented radio is still controversial. The main “competitor” of the Russian scientist is the Italian radio engineer and entrepreneur Guglielmo Marconi (1874-1937), who in 1896 received a patent for “improvement in the transmission of electrical impulses and signals and equipment for this.”

It was he, as well as the German engineer Karl Ferdinand Braun, who received the Nobel Prize in 1909, after Popov’s death, “for his work on the creation of a wireless telegraph.” Another contender for the title of inventor of radio is Nikola Tesla, a Serbian who moved to the United States for permanent residence.

The material was prepared by the online editors of www.rian.ru based on information from RIA Novosti and open sources

Hertz's experiments showed that using electromagnetic waves it was possible to send and receive signals, but all this was done at a very short distance, within the confines of a laboratory table. Having conducted an experiment important for science, Hertz did not see the practical value of using electromagnetic waves and even denied the possibility of their use.

However, these experiments attracted the interest of physicists around the world. In Russia, A.S., a teacher at a higher educational institution in Kronstadt, was one of the first to study electromagnetic waves. Popov, who in April 1895 created the world's first radio receiver, in which the reception of signals was recorded using an electric bell.

The circuit of Popov's transmitter is shown in Figure 1. The oscillatory circuit consists of inductance - the secondary winding of the induction coil L, powered by battery B, and capacity - spark gap ab. If you press key K, a spark jumps in the spark gap of the coil, which is a high-frequency discharge and causes electromagnetic oscillations in antenna A.

The antenna is an open vibrator and emits electromagnetic waves, which, upon reaching the antenna of the receiving station, excite electrical oscillations in it.

To register received waves A.S. Popov used a special device - coherer K, consisting of a glass tube containing metal filings (Fig. 2).

A metal plate B is inserted into the left end of the tube, and wire C, in contact with the sawdust, is inserted into the right end. Under normal conditions, the resistance of the sawdust is high, but under the influence of electrical oscillations, small sparks jump between them, the sawdust sticks together, and the resistance of the coherer decreases sharply. If you shake the tube or lightly hit it, the sawdust will disintegrate and their resistance will increase again. A.S. Popov connected the coherer to a circuit containing a source of EMF B and a bell, the hammer of which, when the bell operated, could strike the rubber tube T. When the resistance of the coherer is high, the current strength constantly flowing in the BBCNB circuit is insufficient to attract the armature in the relay. With the advent electromagnetic wave the coherer resistance drops, the current strength in the BBCNB circuit increases, the armature S of the relay closes at point Q the circuit of the electromagnet M1 connected in parallel with the coherer circuit, and the bell hammer signals the arrival of the wave. In this case, the circuit of the electromagnet M opens, and the hammer strikes the coherer. The coherer resistance increases and the relay opens the bell circuit. The device responds to a single wave with a short call, and to continuously received waves with frequent calls at regular intervals.

The relay allowed A.S. Popov did not register the waves directly received by the antenna, but used their low energy to control the energy source that powers the apparatus that records the appearance of these waves.

In June 1895 A.S. Popov improved his receiver by adding a vertical wire - a receiving antenna - to increase sensitivity, and in March - a telegraph apparatus for receiving verbal text, and was able to record received signals on telegraph tape. On March 24, 1896, the first words of “Heinrich Hertz” were transmitted using Morse code.

Having achieved success, A.S. Popov continued experiments to increase the radio communication range. He used the phenomenon of resonance, for which he used tuning elements in his instruments for a certain wavelength, and already in 1898 A.S. Popov carried out radio communication between the two ships over a distance of 5 km.

In 1899, his student P.N. Rybkin discovered the possibility of receiving radiotelegraph signals by ear. Soon after this A.S. Popov designed the first special radio receiver and thereby laid the foundation for the development of radiotelephone communications.

Although modern radio receivers bear very little resemblance to Popov's receiver, the basic principles of their operation are the same. Any receiver has an antenna in which the incoming wave causes very weak electrical oscillations. These weak signals control the energy sources that power subsequent circuits.

Literature

Aksenovich L. A. Physics in secondary school: Theory. Tasks. Tests: Textbook. allowance for institutions providing general education. environment, education / L. A. Aksenovich, N. N. Rakina, K. S. Farino; Ed. K. S. Farino. - Mn.: Adukatsiya i vyhavanne, 2004. - P. 440-442.

Diagram of the Popov receiver, given in the Journal of the Russian Physical and Chemical Society.

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Radio waves

“Hertz Experience” - The first radio receiver A.S. Popov (1895). Scheme of the first radio receiver by A. S. Popov. Experience of Heinrich Hertz. The first radio receiver by A. S. Popov (1895). Based on his experience, Popov made a conclusion. Zzz z. Explanation of the experimental results. OK. Marconi radio (1896). Basic summary. Alexander Stepanovich Popov (1859 – 1905).

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“Radio Wave Propagation” - Propagation models and frequency ranges (2). Is it possible collaboration?! Superrefraction, waveguide effects and interference in the microwave range. Line of sight with multi-beam reception. Procedures for discussion, approval and acceptance of publications are developed and approved by the Radiocommunication Assembly.

“Communications” - Development of communications. The development of communications has come a long way. From the first radio devices to modern equipment. Popov is the progenitor modern means communications. The circuit of the first radio receiver invented by Popov. Every day the means of communication are becoming more developed. The first radio receivers.

“Radio invention” - 1920. The emergence of radio communications formed the basis for the development of directions. 1888 1922 Conclusion: Armstrong invents a superheterodyne receiver that allows receiving very weak signals. 1903 Thomas Alva Edison, an American inventor, discovered the phenomenon of thermionic emission.

There are a total of 25 presentations in the topic

The design and principle of operation of the radio receiver

A. S. Popova

Performed: pupil 11 "b" class

Ovchinnikova Yu.

Checked: Physics teacher

Gavrilkova I. Yu.

New Oskol 2003

PLAN:

1. Popov’s first radio receiver.

2. Improvement of radio by Popov.

3. Modern radios.

Popov's first radio receiver.

After electricity was discovered, they learned to transmit electrical signals through wires, carrying telegrams and live speech. But you can’t stretch telephone and telegraph wires behind a ship or an airplane, behind a train or a car.

And here radio helped people (translated from Latin radio means “to radiate”; it has a common root with other Latin words radius - “ray”). To transmit a message wirelessly, you only need a radio transmitter and a radio receiver, which are connected by electromagnetic waves - radio waves emitted by the transmitter and received by the receiver.

The history of radio begins with the world's first radio receiver, created in 1895 by the Russian scientist A. S. Popov. Popov designed a device that, in his words, “replaced the electromagnetic senses missing in humans” and responded to electromagnetic waves. At first, the receiver could only “feel” atmospheric electrical discharges – lightning. And then he learned to receive and record on tape telegrams transmitted by radio. With his invention, Popov summed up the work large number scientists from a number of countries around the world.

Various scientists made important contributions to the development of radio engineering: H. Ernest, M. Faraday, J. Maxwell and others. A German physicist was the first to obtain and study the longest electromagnetic waves.

G. Hertz in 1888 A. S. Popov, based on the results of Hertz, created, as already mentioned, a device for detecting and recording electrical oscillations - a radio receiver.

On April 25 (May 7), 1895, at a meeting of the Physicochemical Society, Popov made a report “On the relationship of metal powders to electrical vibrations,” in which he outlined the main ideas about his sensitive device for detecting and recording electromagnetic vibrations. This device was called a lightning detector. The device contains all the main parts of a spark radiotelegraphy radio receiver, including an antenna and grounding.

Lightning detector A. S. Popova.

The first radio receiver had a very simple device: a battery, an electric bell, an electromagnetic relay and a coherer (from Latin word cogerentia - cohesion). This device is a glass tube with two electrodes. The tube contains small metal filings. The operation of the device is based on the effect of electrical discharges on metal powders. Under normal conditions, the coherer has great resistance, since the sawdust has bad contact together. The arriving electromagnetic wave creates an alternating current in the coherer high frequency. The smallest sparks jump between the sawdust, which sinter the sawdust. As a result, the coherer resistance drops sharply (in the experiments of A.S. Popov from 100,000 to 1000 - 500 Ohms, that is, 100-200 times). You can return the device to high resistance again by shaking it. To ensure automatic reception, it is necessary to implement wireless communication, A.S. Popov used a bell device to shake the coherer after receiving a signal. Under the influence of radio waves received by the antenna, the metal filings in the coherer adhered, and it began to transmit electricity from battery. The relay was triggered, turning on the bell, and the coherer received a “light shake”, the adhesion between the metal filings in the coherer weakened, and the next signal was received.

The first radio receiver of A. S. Popov (1895)

The transmitter was a spark gap that excited electromagnetic oscillations in the antenna, which Popov was the first in the world to use for wireless communication. To increase the sensitivity of the device, A.S. Popov grounded one of the coherer terminals and connected the other to a highly raised piece of wire, creating the first receiving antenna for wireless communication. Grounding turns the conductive surface of the earth into part of an open oscillating circuit, which increases the reception range.

Diagram of A. S. Popov’s radio receiver, made by him: N – bell contact; A, B – coherer calls; C – relay contact; PQ – battery terminals, M – antenna contact.

The operating principle of Popov's transmitter and receiver can be demonstrated using an installation in which a dipole with a coherer is connected to a battery through a galvanometer.

At the moment of receiving an electromagnetic wave, the resistance of the coherer decreases, and the current in the circuit increases so much that the galvanometer needle deflects to the full scale. To stop receiving the signal, the coherer filings should be shaken, for example, by lightly tapping a pencil. In Popov's reception station, this operation was performed automatically by the hammer of the electric bell.

Scheme for demonstrating the operating principle of the Popov receiver: K – coherer, B – battery.

Improvement of radio by Popov.

Popov devoted a lot of time and effort to improving his radio receiver. His immediate goal was to build a device for transmitting signals over long distances.

Initially, radio communication was established at a distance of 250 m. Working tirelessly on his invention, Popov soon achieved a communication range of more than 600 m. Then, during the maneuvers of the Black Sea Fleet in 1899. the scientist established radio communication at a distance of over 20 km, and in 1901. The radio communication range was already 150 km. The new transmitter design played an important role in this. The spark gap was placed in an oscillating circuit, inductively coupled to the transmitting antenna and tuned into resonance with it. The methods of signal recording also changed significantly. In parallel with the call, a telegraph machine was turned on, which made it possible to conduct automatic recording signals. In 1899 the possibility of receiving signals using a telephone was discovered.

5 years after the construction of the first receiver, a regular wireless communication line began to operate over a distance of 40 kilometers. Thanks to the program transmitted through this line in the winter of 1900, the icebreaker Ermak removed fishermen from the ice floe who had been carried out to sea by the storm. Radio, which began its practical history by saving people, has become a new progressive form of communication of the 20th century.

Modern radios.

Although modern radio receivers bear very little resemblance to Popov's receiver, the basic principles of their operation are the same as in his device. A modern receiver also has an antenna in which the incoming wave produces very weak electromagnetic oscillations. As in A. S. Popov’s receiver, the energy of these oscillations is not used directly for reception. Weak signals They only control the energy sources that power subsequent circuits. Nowadays such control is carried out using semiconductor devices.

Circuit diagram of a simple radio receiver.

Modern radio receivers detect and retrieve transmitted information. Reaching the receiver antenna, radio waves cross its wire and excite very weak frequencies in it. The antenna simultaneously contains high-frequency oscillations from many radio transmitters. Therefore, one of the most important elements of a radio receiver is a selective device that can display the desired signal from all received signals. Such a device is an oscillatory circuit. The circuit receives signals from the radio transmitter whose high-frequency oscillations coincide with the natural frequency of the receiver circuit. The purpose of other elements of the radio receiver is to amplify the received vibrations, to separate them from the vibrations audio frequency, amplify them and convert them into information signals.

There are 2 types of radio receivers: direct amplification receivers, in which high-frequency oscillations before the detector are only amplified, and superheterodyne, in which received signals are converted into oscillations of a certain intermediate frequency, amplified and only after that they arrive at the detector.

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Bibliography :

1) Zubkov B.V., Chumakov S.V. "Encyclopedic Dictionary of Young Technicians", Moscow, "Pedagogy", 1988.

2) Orekhov V.P. “Oscillations and waves in a high school physics course,” Moscow, “Prosveshchenie,” 1977.

3) Myakishev G. Ya., Bukhovtsev B.B. "Physics 11", Moscow, "Enlightenment", 1993.