Material from Wikipedia - the free encyclopedia

Dynamo machine or dynamo is an obsolete name for an electrical generator (direct current generator).

The dynamo was the first electrical generator to be used in industry. Later it was replaced by alternating current generators, since alternating current can be transformed.

In modern times the term dynamo used primarily to refer to a small bicycle generator that powers a bicycle headlight, as well as a small generator built into electric flashlights - the so-called. electrodynamic or self-charging flashlights that can operate autonomously without batteries or accumulators and do not require recharging from a stationary 220 V power supply or changing batteries and can operate for an unlimited time in the field.

In modern times, the dynamo is also used in some types of neon backlight series trainers and also in gyroscopic hand trainers.

Description

A dynamo consists of a coil of wire rotating in a magnetic field created by a stator. The rotational energy, according to Faraday's law, is converted into alternating current, but since in the 19th century they did not know how to practically use alternating current, they used a brush-collector assembly in order to invert the changing polarity (to obtain a direct current output). The result was a pulsating current of constant polarity.

Story

The first dynamo was invented by A. Jedlik in 1827. He formulated the dynamo concept six years earlier than it was announced by Siemens, but did not patent it.

see also

Write a review about the article "Dynamo"

Notes

Bicycle components, tools and accessories Frame Wheels Transmission Brakes, cables (hydraulic lines) and handles Clothing and protection Cloth Protection

An excerpt characterizing Dynamo

The wolf stopped running, awkwardly, like a sick toad, turned his big forehead to the dogs, and also softly waddling, jumped once, twice and, shaking a log (tail), disappeared into the edge of the forest. At that same moment, from the opposite edge of the forest, with a roar similar to crying, one, another, a third hound jumped out in confusion, and the whole pack rushed across the field, through the very place where the wolf had crawled (ran) through. Following the hounds, the hazel bushes parted and Danila’s brown horse, blackened with sweat, appeared. On her long back, in a lump, lolling forward, sat Danila, without a hat, with gray, tousled hair over a red, sweaty face.
“Whoop, whoop!” he shouted. When he saw the count, lightning flashed in his eyes.
“F...” he shouted, threatening the count with his raised arapnik.
-About...the wolf!...hunters! - And as if not deigning to deign the embarrassed, frightened count with further conversation, he, with all the anger he had prepared for the count, hit the sunken wet sides of the brown gelding and rushed after the hounds. The Count, as if punished, stood looking around and trying with a smile to make Semyon regret his situation. But Semyon was no longer there: he, taking a detour through the bushes, jumped the wolf from the abatis. Greyhounds also jumped over the beast from both sides. But the wolf walked through the bushes and not a single hunter intercepted him.

Nikolai Rostov, meanwhile, stood in his place, waiting for the beast. By the approach and distance of the rut, by the sounds of the voices of dogs known to him, by the approach, distance and elevation of the voices of those arriving, he felt what was happening on the island. He knew that there were arrived (young) and seasoned (old) wolves on the island; he knew that the hounds had split into two packs, that they were poisoning somewhere, and that something untoward had happened. Every second he waited for the beast to come to his side. He made thousands of different assumptions about how and from which side the animal would run and how it would poison it. Hope gave way to despair. Several times he turned to God with a prayer that the wolf would come out to him; he prayed with that passionate and conscientious feeling with which people pray in moments of great excitement, depending on an insignificant reason. “Well, what does it cost you,” he said to God, “to do this for me! I know that You are great, and that it is a sin to ask You for this; but for the sake of God, make sure that the seasoned one comes out on me, and that Karai, in front of the “uncle” who is watching from there, slams into his throat with a death grip.” A thousand times during these half-hours, with a persistent, tense and restless gaze, Rostov looked around the edge of the forest with two sparse oak trees over an aspen underhang, and the ravine with a worn edge, and the uncle’s hat, barely visible from behind a bush to the right.

Now a lot of digital equipment is breaking down, computers, printers, scanners. Time is like this - the old is replaced by the new. But equipment that has failed can still serve, although not all of it, but certain parts of it for sure.
For example, stepper motors of various sizes and powers are used in printers and scanners. The fact is that they can work not only as motors, but also as current generators. In fact, this is already a four-phase current generator. And if you apply even a small torque to the engine, a significantly higher voltage will appear at the output, which is quite enough to charge low-power batteries.
I propose to make a mechanical dynamo flashlight from a stepper motor of a printer or scanner.

Making a flashlight

The first thing you need to do is find a suitable small stepper motor. Although, if you want to make a flashlight larger and more powerful, take a large engine.

Next I need a body. I took it ready. You can take soap dishes, or even glue the case yourself.

We make a hole for the stepper motor.

We install and try on the stepper motor.

From an old flashlight we take the front panel with reflectors and LEDs. Of course, you can do all this yourself.

We cut out a groove for the headlight.

We install a luminary from an old flashlight.

We make a cutout for the button and install it in the groove.

In the free area we place the board on which the electronic components will be placed.

Flashlight electronics

Scheme

In order for LEDs to shine, they need constant current. The generator produces alternating current, so a four-phase rectifier is needed that will collect current from all motor windings and concentrate it in one circuit.

Next, the resulting current will charge the batteries, which will store the resulting current. In principle, you can do without batteries - using a powerful capacitor, but then the glow will only appear at the moment the generator is turned.
Although there is another alternative - to use an ionistor, it will take considerable time to charge it.
We assemble the board according to the diagram.

All parts of the flashlight are ready for assembly.

Lantern dynamo assembly

We attach the board with self-tapping screws.

We install the stepper motor and solder its wires to the board.

We connect the wires to the switch and headlight.

Here is the almost assembled lantern with all the parts.

Rice. 1. Farade disk I

Previous articles in this series examined the first electric motors, created at the beginning of the 19th century, powered by the only known source - a galvanic battery. The low economic efficiency of such an electrochemical source, which prevents the replacement of steam engines with electric ones, forced inventors to look for other, electromechanical methods of generating electricity. This article reflects the process of creating DC electric generators, as a result of which the phenomenon of self-excitation due to positive feedback, called the dynamo principle, was discovered.

The first electromechanical generator was proposed by Faraday in 1832 immediately after his discovery of the law of electromagnetic induction (Fig. 1). The Faraday disk contains: a stator in the form of a horseshoe magnet - 1 and a copper disk (rotor) - 2, equipped with movable contacts on the axis and rim.

When a disk rotates in a magnetic field, an EMF of constant sign is induced in it, causing induced currents that flow radially according to the right-hand rule, i.e., between the axis and the rim (in this case, from bottom to top). According to Lenz's rule, induced currents create a magnetic flux that opposes the flux of the magnet, i.e., directed along the axis of rotation of the disk. This is the only known unipolar DC generator that is still used to generate large currents. The remaining DC generators are essentially AC generators with a rectifier (commutator) at the output.

Rice. 2. Pixie Generator

The first alternating current generator was built in France by master Hippolyte Pixii in the same 1832. During his short life of 27 years, Pixie created many scientific instruments, including a dilatometric thermometer and a vacuum pump. The Pixie generator is shown in Fig. 2, where they are indicated: 1 – stator with two coils connected in series, 2 – rotor with a permanent magnet, 3 – brush commutator (rectifier). The power lines of a rotating magnet cross the winding of the coils, inducing an emf close to harmonic in them. The idea of ​​the coils and rotating magnet belongs to the inventor, who sent a letter to Faraday, signed with the Latin initials P.M. The probable name of the inventor, Frederick Mc-Clintock, remained unknown for a long time. Faraday immediately published this letter in a scientific journal. However, this device generated alternating current, whereas at the beginning of the 19th century only direct current was used. Therefore, Pixie, on the advice of Ampere, equipped him with a brush commutator. The Pixie generator was used by E. H. Lenz to prove the principle of reversibility of an electric machine, discovered by him in 1833. However, for a long time, engines and generators developed separately.

When creating a high-voltage remote fuse for sea mines in 1842, Jacobi proposed placing magnets on the stator and the winding on the rotor, which increased the compactness of the generator. The Jacobi generator is shown in Fig. 3, where they are indicated: 1 – stator with two permanent magnets, 2 – shaft, 3 – armature (rotor with winding), 4 – commutator, 5 – multiplier, i.e. a step-up gearbox to increase the rotor speed.

Rice. 3. Jacobi generator

The generator proposed by the English engineer Frederick Holmes to power the arc lamp he patented had a similar design. For the serial production of generators, the Alliance company was created in 1856. The generator view is shown in Fig. 4, where: 1 – stator with permanent magnets; 2 – rotor with winding (armature); 3 – centrifugal regulator, 4 – brush shift mechanism.

It used a Watt centrifugal regulator to automatically maintain the output voltage by shifting the brushes from neutral as the load current changed, thereby compensating the armature reaction. The generator had 50 permanent magnets and developed a power of 10 hp. weighing up to 4 tons. In total, more than 100 Alliance generators were produced, which were used, in addition to arc searchlights for lighthouses, in electroforming.

Rice. 4. Generator "Alliance"

In operation, machines with permanent magnets have discovered the unpleasant disadvantage of a decrease in output voltage due to the gradual demagnetization of magnets from vibration and aging. Another disadvantage of excitation from permanent magnets was the inability to regulate their magnetic flux to stabilize the generated voltage. To combat these shortcomings, it was proposed to use electromagnetic excitation, which, moreover, as noted in the article, ensures greater compactness. Thus, the successful English inventor Henry Wilde received a patent in 1864 for a generator with a separate low-power permanent magnet exciter mounted on a common shaft with the generator. Wilde did not have a university education and began his career as a mechanic's apprentice, but he managed to establish the production of his generators for electroplating. However, it became clear that the presence of permanent magnets in generators was a serious hindrance to the development of telegraphy and electric lighting.

A fundamental solution to the problem appeared after the discovery of the possibility of self-excitation of generators, which Siemens called the dynamoelectric principle, or dynamo principle. The idea of ​​self-excitation is that - as shown in Fig. 5 – the initial excitation flux when starting the machine is created by the residual magnetization of the magnetic circuit, where the generator voltage is removed from the armature winding I, and the machine is excited either by winding OB1 connected in series with the load R n, or by winding OB2 connected parallel to the armature through an adjusting resistor R(so-called shunt excitation). Next, the excitation flux increases due to positive feedback from the generated current.

Rice. 5. Self-excited generator circuit

One of the first to point out the possibility of self-excitation of a generator in a patent of 1854 was the Danish engineer and organizer of railway communication, S?ren Hjorth. However, fearing the weakness of the residual magnetization, he supplemented the generator with permanent magnets. This Hiort generator was never implemented. Independently of Hiorth, the idea of ​​self-excitation was expressed in 1856 by professor at the University of Budapest Anjes Jedlik (?nyos Jedlik). He also proposed one of the first electric motors, described in the article. However, Yedlik did not patent his inventions and published information about them very sparingly, so his innovative proposals went unnoticed.

In practice, the idea of ​​self-excitation was realized only ten years later at the same time by several inventors. In a patent application in December 1866, an English telegraph company engineer and Faraday's student, Samuel Alfred Varley, proposed a generator circuit similar to the Jacobi generator, in which, however, the excitation winding replaced permanent magnets. The generator circuit is shown in Fig. 6, where: 1 – excitation electromagnets, 2 – armature, 3 – commutator, 4 – additional adjustment resistor. Before starting, the excitation cores were magnetized with direct current.

Rice. 6. Varley Generator

A month later, in January 1867, a report by the famous German inventor and industrialist Werner Siemens was presented at the Berlin Academy of Sciences with a detailed description of a self-excited generator, which he called a dynamo. Before starting, the generator was turned on as a motor to magnetize the excitation. Subsequently, Siemens established wide industrial production of such generators in Germany.

In February of the same 1867, the famous English physicist Charles Wheatstone patented and demonstrated a shunt-excited generator (Fig. 5). The owner of a musical instrument workshop who took over the business from his father, later a professor at King's College in London, Wheatstone is also known for his inventions of the resistance measurement method (Wheatstone bridge), the single-phase synchronous electric motor, the concertina musical instrument, the stereoscope, the chronoscope (electrical stopwatch) and the improved view of the Schilling telegraph.

A discussion arose in the press about the priority of this technical solution, which was also claimed by Wilde and Hiort. It should be noted that there are three types of priority: scientific, patent and industrial. Scientific priority belongs to the scientist who first published or publicly demonstrated any device, effect or theory. Industrial priority belongs to the person or company that first established the production of a product and its widespread introduction. For example, in the discovery of radio, scientific priority belongs to Popov, and patent and industrial priority belongs to Marconi. Regarding the self-excited generator, patent priority should be recognized for Varley, scientific priority for Jedlik and Siemens, and industrial priority for Siemens. Wheatstone has priority in a particular, albeit very important, technical solution - shunt excitation.

Further improvement in the characteristics of the dynamo was associated with a change in the design of its armature through the use of a ring armature in 1867 by the Belgian electrical engineer Zenobe Gramme, and then the introduction of drum winding, proposed in 1872 by Hefner Alteneck, the leading designer Siemens-Halske company. After this, electric motors and generators practically took on their modern form. However, by the end of the 19th century, due to the widespread introduction of alternating current systems, the main share of electricity at hydro and thermal power plants was already generated by alternating current generators.

Rice. 7. Geodynamo model

As for the dynamo principle itself, it was remembered again in the twentieth century to explain the causes of terrestrial magnetism, which Einstein in 1905 called one of the five main mysteries of physics of that time. So far, no definitive answer has been obtained, confirmed by computer modeling or physical experiments, but the most popular theory is called hydromagnetic dynamo (geodynamo). Since the time of William Gilbert (late 16th century), it has been established that the Earth is a giant magnet, the lines of force of which are directed from the south pole to the north. According to Maxwell's equations, magnetic fluxes can only be created by currents, so it was natural to assume that the Earth is an electromagnet, the currents of which flow in planes parallel to the equator, and the core is the solid ferromagnetic core of the Earth, shown in Fig. 7, with the assumed vertical location of the Earth's rotation axis. This iron-nickel core (1) with a diameter of about 1200 km is surrounded by a liquid shell (2) of the same metals 2300 km thick, followed by rocks of the Earth's mantle and crust.

If we assume that due to the rotation of the Earth (3), concentric flows are formed in the liquid shell of the core in planes parallel to the equator (not shown in the figure), then currents can be induced in them due to the intersection of field lines (4) by the magnetic flux from the solid core - as in a Faraday generator. However, a solid core fundamentally cannot be magnetized, since its temperature, caused by thermonuclear reactions, is above 5000 o C (as on the surface of the Sun), and all ferromagnetic materials lose their magnetic properties above the Curie point (about 750 o C). In addition, scientists could not offer a reasonable explanation for the formation of such concentric flows. Therefore, a more complex model called convective geodynamo has now been adopted.

The surface temperature of the liquid core at the boundary with the mantle (5) is approximately 600 o C lower than the temperature of the solid core, which causes radial convective flows of liquid (6), which, under the influence of Kariolis forces caused by the rotation of the Earth, twist into vortices (7), rotation axis which coincides with the axis of rotation of the Earth. Further, in these liquid vortices, similar to a Faraday disk, currents are induced, creating magnetic fluxes (4) along the Earth’s rotation axis.

More complex is the question of the initial formation of the Earth's magnetic field. In 1919, the Irish physicist and mathematician Joseph Larmor, a graduate of Cambridge University, one of the creators of the electron theory and the founders of the relativistic theory, proposed the idea of ​​self-excitation, similar to the process in a dynamo, to solve it. The necessary initial magnetization of the Earth's mantle could be caused by the Sun's magnetic field directed along the axis of rotation. Then, due to the positive feedback mechanism in the liquid vortices, the currents magnetizing the mantle gradually increased until local heating of the liquid core due to ohmic losses began to destroy convective flows and the Earth’s magnetic field assumed a stable modern level.

In 1831, the English physicist Michael Faraday discovered a very interesting phenomenon and derived the law of electromagnetic induction from it. The essence of electromagnetic induction is that in a copper wire, if it is rotated in a non-uniform magnetic field, that is, between the poles of a magnet or electromagnet, an electromagnetic field appears. The electromagnetic field excites the movement of electrons, and an electric current begins to flow through the conductor.
But where did the electromagnetic field and electric current come from, you ask, if we only have ordinary copper wire wound on a metal rod?
The fact is that the metal rod has a magnetic property. But for now this rod is non-magnetic, because the magnetic particles are located in it randomly, at random. If these magnetic particles are put in order, that is, arranged according to the magnetic poles, then the rod acquires the property of a magnet and will attract metal objects to itself. This ordering of magnetic forces can be achieved by magnetizing the rod with a permanent magnet or with an electric current using a coil. This can also be done by strongly rotating one electromagnet around another.
There are always weak traces of magnetism in the rod of an electromagnet, which excite a weak electric current in the windings. And when they begin to rotate one electromagnet around another, the electromagnet becomes even more magnetized, and the strengthening of magnetic forces increases the current in the windings, etc. Thus, at the highest speed of rotation of the electromagnet, the current in the winding reaches its full strength. Collected using a special device called a collector, the electric current is directed to an external electrical circuit. Therefore, the voltage supplied by such a device depends on the magnetic ability of the core, the speed of rotation and the length of the electromagnet winding. But the practical application of this law initially went not through the creation of an electricity producer, but through its consumer—an electric motor.
Soon after Faraday's discovery of the law of electromagnetic induction, in the same 1831, the first device was built that converted electrical energy into mechanical energy. It should be noted that Faraday, having discovered the phenomenon of electromagnetic induction, had not yet created an electric motor.
The first inventors of electric motors adhered to the operating principles of steam engines when designing them.
Thus, one of the first electric motor designers, Bur-buz, made an exact copy of a steam engine, replacing the cylinders with electromagnets and the pistons with metal anchors. The voltage switch - a modern manifold - was also made in the form of a spool box of a steam engine. Such an engine consisted of two pairs of electromagnets, between which a stand with a rocker arm was installed. Anchors were placed on the rocker arm, and at the same time the rocker arm was connected by a system of levers to the flywheel. From the flywheel cam there was a rod to the switch in the form of a spool box. When the current was turned on, one pair of electromagnets attracted the armature to itself, moving the levers and turning the flywheel. When the armature was attracted to the first pair of electromagnets, the switch rod moved the slider and, breaking the existing circuit, immediately turned on the circuit of the second electromagnet. The second armature was attracted to the second pair of electromagnets, the levers moved and rotated the flywheel further.
The first electric motors, operating on the principle of the so-called reciprocating motion, were very weak and could not be practically used. But already in 1834, Russian academician Boris Semenovich Jacobi, who discovered electroplating, built the first electric motor without reciprocating motion. In his engine, the working part, that is, the anchor, performed a rotational movement, as in a modern electric motor.
Jacobi's first electric motor was very simple in design: a horizontal motor was installed above the electromagnets with wooden circles mounted on it, into which metal rods were inserted around the circumference. A metal sprocket with a number of teeth equal to the number of metal armature rods was attached to the end of the axle. A spring was attached to the sprocket, which, when the armature rotated, alternately touched the teeth of the sprocket and thereby periodically turned on voltage to the winding of the electromagnet, and the latter, alternately attracting the armature rods, rotated it on the axis.
Later, in 1838, Jacobi designed an electric motor, which he himself practically used on the world's first electric motor boat. This motor consisted of 4 stator electromagnets and 4 rotor electromagnets. Due to the fact that Jacobi also used electromagnets on the armature rotor in this motor, the motor already had practical power.
While engaged in further research and improvement of his electric motor, Jacobi noticed that if, by applying mechanical force, the armature of his electric motor is rotated, then an electric current arises in the windings and thus the electric motor turns from a consumer of electricity into its producer. This was a new discovery by the Russian scientist, which served as the beginning of the creation of an electrical energy generator—a dynamo. Thus, ways were outlined for the direct application of the law of electromagnetic induction discovered by Faraday, as already mentioned at the beginning of this section.
Together with the famous scientist Lenz, Jacobi determined the basic laws of electric current and the principles on which electric motors operate.
Friedrich Engels defined these new discoveries in the field of electricity as follows: “...This is a colossal revolution. The steam engine taught us to transform heat into mechanical movement, but the use of electricity will open the way for us to convert all types of energy - heat, mechanical movement, electricity, magnetism, light - into one another and back again and use them in industry (Marx and Engels , op., vol. XXVII, p. 289.)
Thanks to the improvement of electric motors, we already have the opportunity to convert any type of energy into one another and successfully use all types of energy for the development of the socialist national economy.
Russian and, in particular, Soviet scientists have done extremely much in the field of improving electric motors and generators, as well as in the field of magnetology.
Since the birth of electrical engineering, much attention has been paid to the study of the magnetic properties of iron, since it was the main building material of electric motors and the success of the new engine depended on its magnetic properties. The remarkable research of the Russian scientist Alexander Grigorievich Stoletov, carried out in 1872, was fundamental in this area. He established that the magnetic permeability of iron is not constant. It varies depending on the structure of the iron and the degree of its magnetization. The scientific calculations derived from this by Stoletov are still used by scientists and engineers in the design of electric motors.
Russian electrical engineer Pavel Nikolaevich Yablochkov (1847-1894), inventor of the first electric arc lamp, was the first to build a drum-type electric motor armature, which is the most advanced design. P. N. Yablochkov was the first in the world to build an alternator—an alternating current generator, which is now used in all power plants.
A revolution in the field of electricity generation was made by the Russian scientist M. O. Dolivo-Dobrovolsky with his invention of a three-phase current generator in 1890.
A great contribution to the development of magnetology—the science of magnets and magnetic phenomena—was made by the Soviet magnetologist, full member of the USSR Academy of Sciences, Stalin Prize laureate Nikolai Sergeevich Akulov. He discovered an important law known as Akulov's law. Using this law, it is possible to determine in advance how, when individual metals are magnetized, their electrical conductivity, thermal conductivity and other qualities change.

A generator that produces electrical energy through rotation (mechanical energy) is called a dynamo. Due to its properties, the direct current generated by it is not used in everyday life as often as alternating current. All power plants are equipped with giant alternating current generators (alternators). Despite this, the dynamo remains a relevant device that serves well in some electrical fields, for example, when charging batteries. Therefore, a small generator assembled with your own hands will always find a use.

Who invented the dynamo and how does it work?

In 1831, the English physicist Faraday discovered an unusual electromagnetic phenomenon. An electromagnetic field arose in the copper wire during rotation between the magnetic poles. It was this that excited the movement of electrons along the conductor. Based on research, the physicist formulated the law of electromagnetic induction. The conductor was a copper wire wound onto a metal rod with a magnetic property. When the magnetic particles in the rod were aligned with the poles, it turned into a magnet and attracted metal objects to itself. To magnetize the rod, you can use a coil or a permanent magnet. The effect occurs when one electromagnet rotates strongly around another.

In the same year, a device for converting electrical energy into mechanical energy appeared. The first electric motors resembled steam engines: only electromagnets were installed instead of cylinders, and metal armatures were installed instead of pistons.

In 1834, Russian academician Boris Jacobi created the first electric motor with a rotating armature. Four years later, the academician used an improved electric motor on the world's first motor boat. The world's first alternating current generator was built by Pavel Yablochkov. And the invention of another Russian scientist M. Dolivo-Dovolsky - a three-phase current generator - was truly revolutionary.

DIY dynamo, its elements

In order to build a dynamo, you will need such basic elements as a housing, a rotating armature, a commutator, a brush holder, brushes, and insulated copper wire.

Let's consider the preparation of each element separately.

Dynamo device
Frame	There are different options for making the case. A tin can or a piece of pipe (diameter 100 mm) is suitable for it. First, you need to cut out the bottom of the can and weight the body. To do this, wrap a strip of iron of the same width very tightly in several rows on the inside or outside of the can. Then we rivet or solder the strip to the body. Secondly, we make cores for electromagnets and shoes for them from tin or iron. We take strips of tin along the width of the body, bend them, put them on top of each other, fasten them with iron wire and solder them along the sides. We attach the cores to the holes in the housing located opposite each other. Using screws, screw the body to the block (wooden or metal). In the housing we make two bearing strips (brass or thick sheet metal, size 110x20 mm) and a stand (80x20 mm) to secure the armature. We solder the strips in a cross pattern and make a hole in the center along the diameter of the axis. The same hole in the rack 10 mm from the end. Copper tubes (10-15 mm with a diameter of 8 mm) can be soldered into the bearing holes. We solder the first bearing to the body with the ends of the strips, after which the system will bend outward.
Rotating anchor	The anchor must be made carefully, since it largely determines how the dynamo will work. You can assemble an anchor from tin plates. The thickness of all plates must be equal to the thickness of the body (50 mm); their manufacture requires special precision. Approximately 120 circles (46 mm in diameter) will have to be cut out of iron. We divide each circle into eight sectors using a compass, make markings through the center of the circle, and in the center of the circles we draw two circles with a diameter of 8 and 38 mm. At the intersection of the large circle with the sector lines, we draw another 8 mm circles. On all round plates, where the circles are drawn, we accurately drill eight 8 mm holes. We tightly fasten the plates with nuts and put them on the axle, you should get an anchor with round longitudinal grooves. We round off sharp corners in the grooves with a file.

Manufacturing of commutator and brush holder

When assembling the dynamo, in particular the commutator and brush holders, attention and accuracy are required.

Collector		The collector can be made of a tube (copper, brass) or assembled from plates. You will need a tube with a diameter of 20-25 mm and a length of 25-30 mm, which is sawn into 4 equal parts. Two two-millimeter holes are drilled into the plates. Then we cut out a cylinder (diameter 20-25 mm, length 25 mm) from fiber or ebonite, dry wood will also do. We make a hole in the center of the cylinder so that it can fit tightly onto the armature axis. We attach the plates to the cylinder using small screws, each time leaving a space of 1-2 mm between them. You can use twisted wire and insulating tape. The screws should not touch the axle, otherwise there will be a short circuit. We fill the gaps between the plates with rosin.
Brush holder and brushes		A brush holder with brushes is used to relieve stress in the commutator. The brushes must extend and rotate around the axis of the armature to change the force and angle of pressure on the commutator. The base, 10 mm thick, will be made of fiber, ebonite or paraffin wood. Let's drill three holes in it so that the two outer ones will fit the bolts. We take copper bolts or 35 mm radio contacts. We screw in the bolts securing the brushes with nuts for clamping. The hole in the center should be equal to the diameter of the copper tube that was used for the first bearing in the housing. Opposite the central hole in the end of the block, we drill a through hole and make a thread for the fastening screw. We take a screw (for wood - a screw) with a slot or edges on the head. Make a hole slightly smaller than the diameter of the screw, screw in the screw. First screw it in 2-3 turns, then turn it out, repeating until it fits in three turns freely. Then we process the next pass with the same screw. We make a bearing frame, drill a hole in the upper end of which, insert a piece of copper tube and solder it. Brushes can be made in different ways, from copper, brass plates or carbon brushes. These can be plates 40-50 mm long with a cross-section of 10-15 mm. At the end of the brush we drill an oblong through hole 20 mm long for the bolts. This hole will allow you to change the pressure, bringing the brushes closer to the commutator. We secure the brushes with washers. To ensure that the brushes touch the commutator tightly, we sharpen their ends obliquely.

Winding

For the winding we will use copper wire with paper insulation with a cross section of 0.5-0.8 mm. You need to purchase half a kilogram of wire, the thickness of which will affect the voltage and current. For example, when winding with 0.5 mm wire, 25 volts will be generated at a current of 1 ampere, if you take a wire of 0.8 - 8 volts at a current of 3 amperes. Before starting work, divide the wire into two parts. To wind the electromagnet you will need 450 g of 0.5 wire and 60 g for the armature winding. If you bought 0.8 wire, we will set aside 430 g for the electromagnet, and 70 g for the armature.

Dynamo assembly

The dynamo is assembled with your own hands in several stages:

1. For the base we will prepare a board measuring 150x200 mm, 30 mm thick. Let's drill two holes from the edges of the electromagnet ring.
2. We fasten the body to the base with two screws so that the electromagnets are located on the same horizontal line opposite each other.
3. We place wooden blocks on the sides of the body so that it sits firmly and screw them to the base.
4. Then we pass the free end of the armature axis through the bearing on the housing. We insert it into place between the electromagnets.
5. We put a brush holder with brushes on the bearing of the bearing frame from the inside and insert the end of the armature axis with the commutator. A thick metal washer or wire ring must first be placed on the collector.
6. We install the armature so that when it rotates between the electromagnets, it does not touch them and is at the same distance from them. The stand is attached to the base with two screws.

Dynamo Adjustment

• We fix the brushes so that they lightly touch the commutator and do not significantly slow down its rotation.
• Let's check that the connections are correct and that there are no breaks or short circuits. We connect a 15-20 volt battery to the mechanism. If the motor is running and the armature rotates quickly, it means that the dynamo was assembled correctly with your own hands.
• After checking, we connect the dynamo to a drive, for example from a foot-operated sewing machine. We connect a 10-volt battery voltage to the brushes to magnetize the electromagnets. After a minute, the battery should turn off, then we begin to quickly rotate the armature using the drive. We connect a voltmeter or a 12-volt lamp to the wires from the brushes. If everything is assembled correctly, the voltmeter will show voltage and the light bulb will glow.
• Using uniform rotation of the armature, you need to slightly turn the brush holder in the direction of rotation of the armature, then the brushes will spark less and relieve tension better. We will experimentally adjust the installation of brushes.

Bicycle dynamo

A small generator for a bicycle is mounted on the side wall of the tire. It allows you to charge the batteries of mobile phones, receivers and other devices, and lights up the headlights. A bottle dynamo is also called a side dynamo. When driving, the tire drives the dynamo roller, which rotates the electric generator.

For a bicycle generator, you can take a dynamo hub or a dynamo carriage. A non-contact dynamo will also work. She will be able to charge the phone quite successfully.

• A bottle generator creates resistance when running and requires more effort to turn than a hub dynamo. Proper adjustment will help reduce resistance.
• A bottle bike dynamo wears out the tire, unlike a hub dynamo.
• When wet, the dynamo bottle roller may slip over the tire, which will significantly reduce the amount of energy produced.
• A hub dynamo does not require good grip and sealing. They do not make noise like dynamos.

Operating a Bicycle Dynamo

Careful installation of the dynamo is very important, taking into account angle, height and pressure. To start, the bottle style bicycle dynamo is moved and connected, and the hub dynamo is simply engaged manually or automatically.

The dynamo must be operated strictly according to the instructions.

1. Before pedaling, check the voltmeter. It should show voltage (12-13).
2. We select the low power mode, turn on the generator, the indicator light should light up.
3. We pedal, gradually increasing the speed, until the generator turns on. The light went out, the voltmeter showed 13-14. The pedals must be pedaled quickly so that the circuit can maintain power.
4. A bicycle dynamo works more efficiently when power is high. For heavy loads, it is better to start the generator at low power, and after disconnecting the load, switch to high power.

Dynamo charger

In field conditions, a simple “twist” or dynamo for charging your phone is always useful. Chargers with a built-in battery are popular. There are mechanical chargers that also do not take up much space. Many modern “spinners” are equipped with flashlights.

These devices charge mobile phones quite successfully. For example, when rotating the knob 2-3 revolutions per second, you can get a coefficient value from 0.65 to 2.5. Spin it for a couple of minutes and you can talk on the phone for 2 to 5 minutes. It all depends on the model and reception conditions. A handheld dynamo will not be able to power a powerful smartphone with a large display. Mechanical charging will provide results in conjunction with a simple phone along with a hands-free headset.

Dynamo charging will work effectively when the battery is completely discharged, but you can only increase the phone’s charge by twisting the handle up to 50%. When the battery is only half discharged, the spinner becomes a useless toy. If the instructions indicate a maximum charging current of 400 mA with a power of 2 W, then it will not be possible to squeeze out additional energy even if you quickly rotate the handle.

Powerful DIY generator

A powerful electricity generator can be assembled using an old bicycle without eights on the rear wheel. A 28-inch wheel and a 52-tooth front sprocket will do, but other options are possible, such as a 26-inch and a 46-tooth sprocket. First of all, we remove unnecessary parts: the front wheel, tires, gear shift, brakes. Place the bike on the stand.

The generator must be self-contained with two large terminals and one small one. We connect the two large terminals together to form a plus, and the small one with an indicator light. We connect the grounding terminal to the housing (minus). We clean the generator and remove the cooling fan from it. We fix the generator on a bracket behind the seat, the spindle should be outside 10-12 cm from the rim. We select a belt, preferably a toothed one, with a circumference of approximately 82 inches. For 26" wheels, A78 belts are suitable, and for 27" wheels - A80.

To adjust the tension of the alternator, we use a spring-type tensioner. The belt does not need to be tightened too much as the torque is quite low. We attach a voltmeter, a switch and a light bulb to the steering wheel. If there are children in the house, it is necessary to protect the moving parts of the mechanism to eliminate the possibility of injury.