Who created the dynamo machine. The first electric generators and the dynamo principle. Are the Rules violated in the situations depicted?

16.10.2023

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...

Varieties

Let's consider the existing types of factory-made bicycle dynamos.

Bottle shop

This type of bicycle generator is the most affordable and simple. However, its power is not the greatest of all types. The generator drive roller rotates by touching the tire tread while driving.

Bush Dynamo

The hub dynamo is an axial dynamo in its design. Executions of such models can be of various types. The cost of a bushing generator is quite high. Installation is more complicated compared to the bottle version.

When purchasing, you must check the number of spokes and the method of fixing the installation wheel. The advantages of a bushing generator include its protection from moisture, unlike a bottle generator, the drive roller of which slips over the bicycle tire in wet weather. The device is enclosed inside the wheel hub, and the work comes from its rotation.

The disadvantages of such a device include the fact that it is not possible to turn off the operation of the bushing generator.

Chain

The chain version of a bicycle generator is quite rare. However, there are several different versions of this type. The device can be equipped with a USB port for charging mobile gadgets.

The disadvantage of this design is its short service life, since during operation the metal bicycle chain impacts the plastic elements of the generator.

Contactless

This is an original dynamo with a non-contact operating principle. The bicycle wheel plays the role of a rotor. A special hoop with 28 magnets is attached to the wheel. They are arranged alternately, with different poles.

The stator is an induction coil in which electric current is generated. This system includes a battery for energy storage. According to the manufacturer, to ensure normal light flux, it is enough to move at a speed of 15 km per hour.

The advantages of this design are:

No rubbing elements.
Quiet operation.
Unlimited service life (except for batteries).

The disadvantage of the contactless model is the low battery capacity. It only lasts a few minutes. However, many craftsmen easily correct this drawback in various ways, including replacing the battery with a more powerful one.

Other designs

Currently, various interesting devices that are made in China are very popular. Sometimes you see devices that have never been produced anywhere before. Even their operating principle is not always clear, but they work.

This Chinese device can easily be called the bicycle generator of the future. The dynamo from heaven looks similar to science fiction films. Judging by its appearance, it does not require contact with the wheel bar or chain to function. There are also no magnets.

The principle of its operation is not entirely clear. Perhaps this is a technological secret of the manufacturer.

Design features and operation

The most popular dynamo design on bicycles is the bottle design, followed by the hub dynamo. Other types are used much less frequently. Therefore, we will consider the most common models.

Dynamo bottle

The bottle-type dynamo runs on the side of the front tire of a bicycle. It is made in the form of a small generator of electrical energy, and is used to operate the rear light and front headlight of a bicycle, as well as charge electronic mobile devices.

Such a mini-generator can be mounted on both the front and rear wheels. In the first case, the device can be combined with a built-in flashlight. To turn off the generator, a special folding mechanism is provided, which fixes the generator housing in a position where there is no contact with the bicycle wheel tire.

The name of this device comes from the external resemblance of the shape to a bottle. The bottle generator also has another name – side dynamo. The drive rubber or metal roller is driven into rotation on the side of the wheel tire. When the bicycle moves, the tire imparts rotational motion to the bicycle generator roller, which generates an electric current.

Advantages

The disconnected generator drive offers no resistance the movement of the bicycle. When the generator is turned on, the cyclist has to apply more force to move. A hub dynamo, unlike a bottle bicycle generator, always resists wheel rotation, although the value of this resistance is insignificant. If the bottle generator is turned on, but the lights and headlight are not connected to power, then the resistance to the movement of the bicycle is less.
Easy and simple installation . Such a device is easy to install on any bicycle, unlike a hub generator, the installation of which requires the assembly of the entire dynamo wheel with spokes.
Low cost . These models usually cost less than other types of bicycle generators, although there are exceptions to this rule.

Flaws

Complex setup . Careful adjustment and adjustment of the wheel's contact with the tire at a certain angle, tire pressure, and height is required. If the bike is dropped or the retaining screws become loose, the alternator may be damaged. An incorrectly adjusted generator device will make a lot of noise, create excessive resistance, and slip on the wheel. If the fastening screws are too loose, the mechanism may move out of place and get caught in the wheel spokes, which will lead to broken spokes and failure of the bicycle wheel. Some bicycle generators are equipped with special loops that prevent them from getting into the spokes.
Requires physical effort to switch . To activate the generator, it is necessary to move its housing until it comes into contact with the wheel. Bushing generators can be switched on automatically or electronically. You don't need to put any effort into this.
Increased noise . During operation, a humming noise is heard, while hub dynamos do not create noise.
Wheel tire wear . To operate the generator, contact with the tire is required, resulting in friction and tire wear. If you compare it with a dynamo hub, there is no friction with the tire.
Motion resistance . A bottle dynamo offers significantly more resistance to the bike's movement than a hub model. However, when configured correctly, the resistance is negligible, and when switched off, there is no resistance.
Slippage. In wet, rainy weather, the drive roller of the bottle generator will slide on the tire tire, which reduces the generation of electric current and reduces the brightness of the headlight and taillight. Hub generators do not require good tire grip to operate and are not affected by weather or other adverse conditions.

Dynamo hub

The hub design of the bicycle generator was developed in England and produced by various companies in many countries. The power of this design can reach 3 watts at a voltage of 6 volts. Their manufacturing technologies are constantly being improved, the dimensions of the structure are becoming smaller and more powerful. Modern bicycle headlights begin to emit more efficient light, as they are used.

Hub dynamos do not create noise during operation, but their mass is greater than that of other models. There are no rubbing parts in the sleeve version of the device. They operate due to a magnet having many poles and made in the form of a ring. It is located in the bushing body and rotates around a stationary armature with a coil fixed on the axis. The rotational resistance of this design is very low.

Hub dynamos produce alternating current. At low speeds, more electricity is generated compared to the bottle model due to the low frequency of the current. There are rectifier circuits for a dynamo. They are made using a simple bridge circuit of four diodes.

The hub dynamo produces a low voltage, so when using silicon diodes the losses are significant - 1.4 volts. With germanium diodes, losses are reduced and amount to only 0.4 volts.

Working principle of a dynamo

A dynamo produces electric current using the effect of electromagnetic induction. The rotor rotates in a magnetic field, resulting in an electric current in the winding. The ends of the rotor winding are connected to a collector made in the form of rings. Through them, with the help of pressing brushes, electric current enters the network.

The current in the winding has a maximum value if the rotor is perpendicular to the magnetic lines. The greater the angle of rotation of the winding, the less current. Rotation of the winding in a magnetic field changes the direction of the current twice in one revolution. Therefore, the current is called alternating.

A similar generator for direct current is made on the same principle. The difference is in some details. The ends of the winding are connected not to rings, but to half rings, which are isolated from each other. When the winding rotates, the brush contacts each half ring in turn. Therefore, the current flowing to the brushes will have only one direction and will be constant.

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.

A colleague and I were puzzled about autonomous power supplies. I decided to study the market. I present my findings below.

I ask for criticism of specific devices (who uses/has used what), there are probably some other devices that I have not listed, incl. Western analogues.

Introductory: group of 2 people. Autonomous power supplies are required for radio stations and charging AA and AAA batteries (for various useful devices).

What we considered:

1. Solar panels are only suitable for those who have somewhere to place them and a lot of sun. You can’t carry it with you without experiencing difficulties - the more powerful, the more, and besides, it’s fragile, IMHO.

2. Mini-gas is a good thing, but only a large group can afford to build a dam and guard it.

3. A diesel generator is a workable topic, but only as long as there is something to pour into it...

In the meantime, the following remains - dynamos or “manually driven generators”, but on the condition that we will not assemble them ourselves, all characteristics of the devices are given at the links in the text:

Manual drive electric generators EGF-1, EGRP-1, EGRP-2

EGRP-2

EGF-1

All have 12 V output, they differ in power and weight,

Unfortunately, this device only charges its own built-in battery with the dynamo. To charge an AA or AAA battery, you need to manually modify it or try to use USB charging.

A dynamo, or electric current generator, is a device that converts other states of energy into electrical energy: thermal, mechanical, chemical. Bicycle generators that power headlights and taillights remain popular to this day.

Operating principle of an electric current generator

A dynamo generates electrical energy through the principle of electromagnetic induction. Typically, such a device converts mechanical influences directly into electrical impulses. It consists of a rotor (an open wire winding) and a stator in which the poles of the magnet are located. The rotor, without stopping its movement, rotates all the time in a force magnetic field, which inevitably leads to the generation of current in the winding.
The dynamo represents the following diagram of its device. A rotating conductor, or rotor, crosses a magnetic field and a current is generated in it. The ends of the rotor are connected to the ring (collector), through them and the pressure brushes the current moves into the electrical network.

Electric current in a dynamo

The resulting current in the conductor will have the greatest value provided that the rotor is located perpendicular to the magnetic lines. The greater the turn of the conductor, the less current will be. And vice versa. That is, the process of rotating a conductor in a magnetic field forces the generated electric current to change direction twice during one rotation of the rotor. Thanks to this property, this type of current began to be called alternating.
A dynamo for generating direct current is built on the same principle as for alternating current. The difference can only be noticed in the details, when the ends of the metal wire are not fixed to rings, but connected to half rings. Such half-rings are necessarily insulated from each other, which, when the conductor rotates, makes it possible to alternately contact one half-ring and then the other with the brush. This means that the generated current will flow into the brushes exclusively in one direction, in a word - the current will be constant.

How to assemble a dynamo?

A DIY dynamo can be assembled quickly. The basis for the future generator will be a wooden board about 30 mm thick and an area of 150 by 200 mm. The housing is attached to it with two screws so that the electromagnets are positioned horizontally, one against the other. Then, through the bearing attached to the housing, the armature axis is threaded, which is fixed in place between the electromagnets. Brushes are threaded through the inside of the bearing frame and the second end of the armature axis is inserted. The collector is fixed at this end.
Before attaching the bearing frame to the base, the armature must be aligned so that its rotation between the electromagnets does not touch them. The brushes should be located across the shoes of the electromagnets and secured to the bearing. A small pulley is attached to the free end of the rotor.
Electrical installation of the device consists of connecting the ends of the windings for electromagnets with brushes. Also, pieces of flexible wire are connected to them to communicate the device with an external circuit.

Generator and bicycle

A bicycle dynamo demonstrates its power depending on the rotation speed. For example,
If the bicycle is not spinning fast enough or if it stops, the power to the light or other device will stop. But at high speeds, the light bulbs can burn out before their service life.
There are several types of bicycle electric generators:
The hub type is built into the wheel hub. Structurally, it consists of a static core on an axis and a reversing multi-pole magnet in the shape of a ring. Their cost is higher, which is offset by quiet operation and efficiency.
The bottle type is the most popular. The bottle-shaped device is equipped with a small wheel that is driven by friction against the sidewall of the rubber tire of the wheel.

The carriage generator is installed next to the carriage cup, below the frame stays. The movement of the spring-loaded roller is due to friction against the tire tread. It should be mentioned that the bottom bracket and bottle dynamo machine will stop working when exposed to wet conditions.