The simplest dynamo machine diagram and description. Scraps of a priest's life. Diagram of a headlight powered by a dynamo

One of the popular technical devices is a bicycle dynamo. Exactly what types of this device exist, what it is used for and their features.

Types of Bicycle Dynamos

A bicycle dynamo is an electric generator that produces energy to power electrical devices mounted on a bicycle, such as headlights or a power supply for a navigator.

Today, two types of bicycle dynamos are widely used, namely: bottle dynamo and hub dynamo.

Regardless of the type, they both generate electrical energy by rotating a magnet inside a coil. Thus, in bicycle dynamos, the armature is a stationary element, and the stator rotates.

This species got its name due to its external resemblance to an ordinary bottle. The bottle dynamo machine for bicycles was the most common in our country during the Soviet Union. It has undeniable advantages, which include:

• Easy to install and dismantle;
• Possibility of switching off;
• Low price.

At the same time, the bottle type has disadvantages that in some cases make its installation undesirable or even impossible. These should include:

• Installation results in the appearance of an asymmetrical mass on the fork;
• Increased noise during operation;
• Relatively low power output;
• Resistance to movement;
• Reduced efficiency under adverse weather conditions;
• Increased tire wear.

All of the listed shortcomings are predetermined by design features, and without fundamental changes they cannot be eliminated.

The second type, the popularity of which is constantly growing, is the so-called dynamo bushing.

In this case, the bicycle dynamo is structurally designed as a wheel hub. The output voltage of such generators is about six volts with a power of up to two and sometimes three watts.

All the advantages of such a dynamo for a bicycle are determined by its design feature. The “advantages” include:

• Absolutely silent. This is achieved due to the design in the form of a hub for the wheel;
• The dynamo operates without the use of friction, and therefore does not affect the wear of tires and other parts;
• Fully balanced design eliminates imbalance on the fork;
• High efficiency. Since there are no rubbing surfaces, there will be no slippage in any weather conditions;
• Complete isolation from the steel structure of the bicycle electrical wiring circuit.

However, the dynamo hub cannot be turned off; it works constantly when moving. Some experts consider this point to be a disadvantage, but objectively, when the load is turned off, the dynamo will not affect the freedom of rotation of the wheel, and therefore it will be completely wrong to consider the inability to turn off as a disadvantage. Another point is the high mass, although with ideal balancing, this does not affect the driving performance of the bicycle to the extent that it becomes noticeable in practice. The only serious drawback is the price and complexity of the design, as well as the fact that to install such a generator it is necessary to sort out the entire wheel, and this undoubtedly requires certain skills and training.

So, when choosing a dynamo for your two-wheeled friend, remember safety, reliability and focus on your financial capabilities. What kind of dynamics the bike will have is, of course, up to you and no one else to decide.

Since this type of generator is gaining popularity, let's look at some of its features that you need to know and understand.

First of all, if a bottle generator produces a constant electricity, then the bicycle hub dynamo generates alternating voltage. What is the difference? Let's try to figure it out without going too deep into electrodynamics.

Direct current has poles: “plus” and “minus”. Such current always flows in one direction from plus to minus. Alternating voltage has no polarity. In order for a regular incandescent lamp to burn, it does not matter what the current is, direct or alternating. But for an LED headlight, things are different: the LEDs will only work if the current is constant and connected correctly. If you install a dynamo hub on a bicycle, then you must connect the LED headlight through a special rectifier bridge. This will be relevant for any energy consumers powered by a DC source.

Hub dynamo installation

There are no difficulties when installing a bottle generator, but a hub generator for a bicycle will make you work.

First of all, since the design of such a generator itself provides for installation as a supporting bushing, the wheel will have to be removed and completely disassembled. Take care of a set of shortened knitting needles first. After complete disassembly, use short spokes to secure the rim to the hub. Try to install it evenly and evenly, gradually tightening the spokes, and then tightening it to finally strengthen the rim. Then you need to balance and check for runout and imbalance.

Attention! In a bottle-type generator, there is a minus power supply on the body. The dynamo hub has no electrical contact with the body, so you can make the electrical wiring completely insulated or use a metal frame as one of the conductors. If a rectifier bridge is installed, the frame must be attached after it.

I made this friction bike generator for my bike to power my flashlight and rear lights. I found the idea and a lot of information for this pedal generator project on the Internet.

I recently bought a bike to commute to work and around town, and decided that for safety reasons I needed a light. My front light was powered by 2 AA batteries and the back light was powered by 2 AAA batteries, the instructions said the front light would last 4 hours and the back light would last 20 hours in flashing mode.

Although these are good indicators, they still require some attention so that the batteries do not run out at the wrong time. I bought this bike for its simplicity, the single speed means I can just hop on and go, but constantly replacing batteries gets expensive and makes it difficult to use. By adding dynamism to the bike, I can recharge the batteries while I ride.

Step 1: Collecting spare parts

If you want to build a dynamo machine with your own hands, then you will need a few things. Here is their list:

Electronics:

1. 1x stepper motor - I got mine from an old printer
2. 8 diodes - I used a personal power unit used 1N4001
3. 1x Voltage Regulator – LM317T
4. 1x Development board with PCB
5. 2 resistors - 150 Ohm and 220 Ohm
6. 1x radiator
7. 1x Battery connector
8. Solid wire
9. Insulation tape

Mechanical parts:

• 1x Bike Reflector Holder - I removed this from the bike when I connected the lights.
• Aluminum corner blank, you will need a piece approximately 15 cm long
• Small nuts and bolts - I used printer screws and some other used parts
• Small rubber wheel - attaches to the stepper motor and rubs against the wheel as it rotates.

Tools:

• Dremel - It's not entirely necessary, but it makes your life a lot easier.
• Drills and bits
• File
• Screwdrivers, wrenches
• A breadboard for testing the circuit before you put everything on the bike.
• Multimeter

Step 2: Create a circuit

Show 10 more images

Let's make a diagram of a dynamo for a bicycle. It's a good idea to test everything before you solder everything together, so I first assembled the entire circuit on a breadboard without solder. I started with the motor connector and diodes. I unsoldered the connector from the printer's circuit board. Placing the diodes in this orientation changes the AC current coming from the motor to DC (rectifies it).

The stepper motor has two coils and you need to make sure that each coil is connected to the same set of diode banks. To find out which wires from the motor are connected to the same coil, you just need to check the contact between the wires. Two wires are connected to the first coil, and two to the second coil.

Once the circuit is assembled on a breadboard without solder, test it. My motor produced up to 30 volts during normal cycling. It's a 24V stepper motor, so its efficiency seems reasonable to me.

With the voltage regulator installed, the output voltage was 3.10 volts. Resistors control the output voltage, and I chose the 150 and 220 ohm options to produce 3.08 volts. Check out this LM317 voltage calculator to see how I calculated my numbers.

Now everything needs to be soldered on printed circuit board. To make neat connections, I used small gauge solder. It heats up faster and provides a better connection.

In the .Pdf file you will find how everything is connected on the PCB. The curved lines are the wires and the short black straight lines are where you need to solder the jumpers.

Files
Files

Step 3: Installing the Motor

The engine mount was made of an aluminum angle and a reflector bracket. To mount the engine, holes were drilled into the aluminum. One side of the corner was then cut out to make room for the wheel.

The wheel was attached by wrapping duct tape around the motor shaft until the connection was tight enough to push the wheel directly onto the duct tape. This method works well, but it needs to be improved in the future.

Once the motor and wheel were attached to the aluminum, I found a good spot on the frame to mount everything. I attached the blank to the seat tube. My bike's frame is 61cm, so the area where the generator is mounted is quite large compared to smaller bikes. Just find it on your bike the best place for installing a generator.

Once I found a suitable location, I made marks for the aluminum bracket with the reflector bracket installed so it could be cut to size. I then drilled holes in the bracket and aluminum and mounted the structure onto the bike.

I finished assembling the 12 volt bicycle generator by attaching the project box to an aluminum mount with two posts.

Step 4: Connecting the Wires

The bicycle dynamo is assembled, now all you need to do is just connect the wires to the light bulbs. I pushed the ends of the wires past the battery terminals to the headlight, then drilled a hole in the headlight housing to feed the wires through. The wires were then connected to the battery connector. You will also need to make holes in the project box for the wires.

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 a single known source - 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, flowing radially according to the right-hand rule, i.e. between the axle 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 detailed description 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 King's College King's College London, Wheatstone is also famous for his inventions of the resistance measurement method (Wheatstone bridge), the single-phase synchronous electric motor, the concertina musical instrument, the stereoscope, the chronoscope (electric stopwatch) and an improved form 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 by the Belgian electrical engineer Zenobe Gramme in 1867, 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.

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.

In the century before last, DC generators began to be called dynamos - the first industrial generators, which were later supplanted by alternating current generators, suitable for conversion through transformers, and extremely convenient for transmission over long distances with minor losses.

Today, the word "dynamo" usually refers to small bicycle generators (for headlights) or hand generators (for hiking flashlights). As for industrial generators, today all of them are alternating current generators. Let us, however, remember how the first dynamos developed and improved.

The first example of a direct current generator, or unipolar dynamo, was proposed back in 1832 by Michael Faraday, when he had just discovered the phenomenon of electromagnetic induction. It was the so-called “Faraday disk” - the simplest direct current generator. The stator in it was a horseshoe magnet, and the rotor was a manually rotated copper disk, the axis and edge of which were in contact with the current-collecting brushes.

When the disk was rotated, an EMF was induced in that part of the disk that crossed the magnetic flux between the poles of the stator magnet, leading, if the circuit between the brushes was closed to the load, to the appearance of a radial current in the disk. Similar unipolar generators are still used today where large direct currents without rectification are required.

The alternating current generator was first built by the Frenchman Hippolyte Pixie, this happened in the same 1832. The stator of the dynamo contained a pair of coils connected in series, the rotor was a horseshoe-shaped permanent magnet, and the design also included a brush commutator.

The magnet rotated, crossed the coil cores with magnetic flux, and induced a harmonic EMF in them. And the automatic switch served to rectify and produce a constant pulsating current in the load.

Later, in 1842, Jacobi proposed placing magnets on the stator and the winding on the rotor, which would also rotate through a gearbox. This will make the generator more compact.

In 1856, to power Frederick Holmes' serial arc lamps (these lamps were used in lighthouse searchlights), Frederick Holmes himself proposed a generator design similar to the Jacobi generator, but supplemented with a Watt centrifugal regulator to maintain the lamp voltage constant at different load currents, which was achieved by automatically moving the brushes.

Meanwhile, machines with permanent magnets had one significant drawback - the magnets lost their magnetization over time and deteriorated from vibration, as a result, the voltage generated by the machine became lower and lower over time. In this case, the magnetization could not be controlled to stabilize the voltage.

The idea of ​​electromagnetic excitation came as a solution. The idea came to the mind of the English inventor Henry Wilde, who in 1864 patented a generator with a permanent magnet exciter - the excitation magnet was simply mounted on the generator shaft.

Later, a real revolution in generators will be made by the German engineer Werner Siemens, who will discover the true dynamoelectric principle and put the production of new DC generators on stream.

The principle of self-excitation is to use the residual magnetization of the rotor core for starting excitation, and then, when the generator is excited, use the load current as a magnetizing current, or turn on a special excitation winding, powered by the generated current in parallel with the load. As a result, positive Feedback will lead to an increase in the excitation magnetic flux generated by the current.

Among the first to note the principle of self-excitation, or dynamoelectric principle, is the Danish engineer Soren Hiort. He mentioned in his 1854 patent the possibility of using remanent magnetization to realize the phenomenon of electromagnetic induction to obtain generation, however, fearing that the remanent magnetic flux would not be enough, Hiort proposed supplementing the dynamo design with permanent magnets. This generator will never be implemented.

Later, in 1856, Anies Jedlik, a member of the Hungarian Academy of Sciences, would express a similar idea, but he would never patent anything. Only 10 years later, Samuel Varley, a student of Faraday, put into practice the principle of a self-exciting dynamo. His patent application (in 1866) contained a description of a device very similar to a Jacobi generator, only the permanent magnets had already been replaced by an excitation winding - excitation electromagnets. Before the start, the cores were magnetized with direct current.

At the beginning of 1867, inventor Werner Siemens gave presentations at the Berlin Academy of Sciences. He presented to the public a generator similar to the Varley generator, called a “dynamo.” The car was started in engine mode so that the field windings were magnetized. The car then turned into a generator.

This was a true revolution in the understanding and design of electrical machines. In Germany, wide production of Siemens dynamos began - self-excited direct current generators - the first industrial dynamos.

The design of dynamos changed over time: Theophilus Gramm, in the same 1867, proposed a ring armature, and in 1872, the chief designer of the Siemens-Halske company, Gefner Alteneck, proposed drum winding.

This is how the DC generators will take their final form. In the 19th century, with the transition to alternating current, hydroelectric power plants and thermal power plants began to produce alternating current using alternating current generators. But that's a completely different story...

See also on this topic:

Andrey Povny