DIY wireless electricity. Transmitting electricity over a distance wirelessly

Wireless Charging Basics

Wireless transmission electrical energy(WPT) gives us a chance to escape the tyranny of power cords. This technology is now permeating all types of devices and systems. Let's take a look at her!

Wireless way

Most modern homes and commercial buildings are grid powered alternating current. Power plants generate alternating current electricity, which is delivered to homes and businesses using high-voltage power lines and step-down transformers.

The electricity goes to the distribution panel, and then the wiring carries the electricity to the equipment and devices we use every day: lights, kitchen appliances, chargers, and so on.

All components are standardized. Any device rated for standard current and voltage will work from any outlet throughout the country. Although standards vary from country to country, in a given electrical system any device will operate as long as it meets the standards of that system.

A cable here, a cable there... Most of our electrical devices has an AC power cable.

Wireless power transmission technology

Wireless Power Transfer (WPT) allows power to be supplied across an air gap without the need for electrical wires. Wireless power transmission can provide AC power to compatible batteries or devices without physical connectors or wires. Wireless transmission of electrical energy can provide charging mobile phones And tablet computers, unmanned aerial vehicles, cars and other transport equipment. It could even make it possible to transmit electricity generated from solar panels wirelessly in space.

Wireless transmission of electrical energy has begun fast development in area consumer electronics, replacing wired chargers. At CES 2017, many devices using wireless power transmission will be shown.

However, the concept of transmitting electrical energy wirelessly arose around the 1890s. Nikola Tesla, in his laboratory in Colorado Springs, could light a light bulb wirelessly using electrodynamic induction (used in resonant transformer).

Three light bulbs placed 60 feet (18 meters) from the power source were lit and the demonstration was documented. Tesla had big plans; he hoped that his Wardenclyffe Tower, located on Long Island, would transmit electrical energy wirelessly across the Atlantic Ocean. This never happened because various problems, including financing and timing.

Wireless transmission of electrical energy uses fields created by charged particles to transfer energy across an air gap between transmitters and receivers. The air gap is short-circuited by converting electrical energy into a form that can be transmitted through the air. Electrical energy is converted into an alternating field, transmitted through the air, and then converted into usable electrical current by a receiver. Depending on the power and distance, electrical energy can be efficiently transmitted through an electric field, a magnetic field, or electromagnetic waves such as radio waves, microwave radiation, or even light.

The following table lists the various technologies for wireless transmission of electrical energy, as well as the forms of energy transmission.

Wireless Power Transmission Technologies (WPT)

Technology	Electrical energy carrier	What allows the transmission of electrical energy
Inductive coupling	Magnetic fields	Turns of wire
Resonant inductive coupling	Magnetic fields	Oscillatory circuits
Capacitive coupling	Electric fields	Pairs of conductive plates
Magnetodynamic coupling	Magnetic fields	Rotation of permanent magnets
Microwave radiation	Microwave waves	Phased arrays of parabolic antennas
Optical radiation	Visible light / infrared radiation / ultraviolet radiation	Lasers, photocells

Qi charging, an open standard for wireless charging

While some of the companies promising wireless power are still working on their products, the Qi (pronounced "qi") charging standard already exists and devices using it are already available. Wireless Electromagnetic Energy Consortium ( Wireless Power Consortium, WPC), created in 2008, developed the Qi standard for charging batteries. This standard Supports both inductive and resonant charging technologies.

Inductive charging transfers electrical energy between inductors in the transmitter and receiver located on the close range. Inductive systems require the inductors to be in close proximity and aligned with each other; Usually the devices are in direct contact with the charging pad. Resonant charging does not require careful alignment, and chargers can detect and charge a device up to 45mm away; thus, resonant chargers can be built into furniture or installed between shelves.

The presence of the Qi logo means that the device is registered and certified by the WPC.

At the beginning, Qi charging had a small power, about 5 W. The first smartphones using Qi charging appeared in 2011. In 2015, Qi charging power increased to 15 W, which allows fast charging devices.

The following figure from Texas Instruments shows what the Qi standard covers.

Only devices that are listed in the Qi registration database are guaranteed to be Qi compatible. It currently contains more than 700 products. It is important to understand that products bearing the Qi logo have been tested and certified; and the magnetic fields used by these devices will not cause problems for sensitive devices such as mobile phones or e-passports. Registered devices will be guaranteed to work with registered chargers.

Physics of wireless transmission of electrical energy

Wireless transmission of electrical energy for household devices is new technology, but the principles underlying it have been known for a long time. Where electricity and magnetism are involved, Maxwell's equations are still governed, and transmitters send energy to receivers in the same way as in other forms wireless communication. However, wireless power transmission differs from them in its main purpose, which is to transfer the energy itself, and not the information encoded in it.

The electromagnetic fields involved in the wireless transmission of electrical energy can be quite strong and therefore human safety must be taken into account. Exposure to electromagnetic radiation can cause problems, and there is also the possibility that fields generated by electrical energy transmitters may interfere with the operation of wearable or implanted medical devices.

Transmitters and receivers are built into devices for wireless transmission of electrical energy in the same way as the batteries that will be charged by them. Actual conversion patterns will depend on the technology used. In addition to the transmission of electricity itself, the WPT system must provide communication between the transmitter and the receiver. This ensures that the receiver can notify Charger that the battery is fully charged. Communication also allows the transmitter to detect and identify the receiver in order to adjust the amount of power sent to the load, as well as monitor, for example, battery temperature.

In wireless transmission of electrical energy, the choice of either near-field or far-field concepts matters. Transmission technologies, the amount of energy that can be transmitted, and distance requirements influence whether a system will use near-field radiation or far-field radiation.

Points for which the distance from the antenna is significantly less than one wavelength are in the near zone. The energy in the near field is non-radiative, and the oscillations of the magnetic and electric fields are independent of each other. Capacitive (electrical) and inductive (magnetic) coupling can be used to transfer energy to a receiver located in the near field of the transmitter.

Points for which the distance from the antenna is greater than about two wavelengths are in the far field (there is a transition region between the near and far fields). Far-field energy is transmitted in the form of ordinary electromagnetic radiation. Far-field energy transfer is also called energy beam. Examples of far-field transmission are systems that use high-power lasers or microwave radiation to transmit energy over long distances.

Where does Wireless Power Transmission (WPT) work?

All WPT technologies are currently under active research, with much of it focused on maximizing power transfer efficiency and exploring technologies for magnetic resonance coupling. In addition, the most ambitious ideas are to equip the premises with a WPT system in which a person will be, and the devices he wears will be charged automatically.

Globally, electric buses are becoming the norm; plans to introduce wireless charging for London's iconic double-decker buses are in line with bus systems in South Korea, the US state of Utah and Germany.

An experimental system for wirelessly powering drones has already been demonstrated. And, as mentioned earlier, current research and development is focused on the prospect of meeting some of the Earth's energy needs through the use of wireless power transmission and solar panels located in space.

WPT works everywhere!

Conclusion

While Tesla's dream of wirelessly transmitting power to any consumer is still far from being realized, plenty of devices and systems are using some form of wireless power transmission right now. From toothbrushes to mobile phones, from personal cars to public transport, there are many applications for wireless transmission of electrical energy.

Wireless electricity has been known since 1831, when Michael Faraday discovered the phenomenon of electromagnetic induction. He experimentally established that a changing magnetic field generated by an electric current can induce an electric current in another conductor. Numerous experiments were carried out, thanks to which the first electrical transformer appeared. However, to fully implement the idea of ​​transmitting electricity over a distance in practical application Only Nikola Tesla succeeded.

At the Chicago World's Fair in 1893, he demonstrated the wireless transmission of electricity by lighting phosphorus bulbs that were spaced apart. Tesla demonstrated many variations on the transmission of electricity without wires, dreaming that in the future this technology would allow people to transmit energy over long distances in the atmosphere. But at this time this invention of the scientist turned out to be unclaimed. Only a century later did people become interested in Nikola Tesla’s technologies Intel and Sony, and then other companies.

How it works

Wireless electricity literally refers to the transmission of electrical energy without wires. This technology is often compared to the transmission of information, such as Wi-Fi, cell phones and radios. Wireless electricity– This is a relatively new and dynamically developing technology. Today, methods are being developed to safely and efficiently transmit energy over a distance without interruption.

The technology is based on magnetism and electromagnetism and is based on a number of simple principles work. First of all, this concerns the presence of two coils in the system.

• The system consists of a transmitter and a receiver, which together generate an alternating magnetic field of variable current.
• This field creates voltage in the receiver coil, for example, to charge a battery or power a mobile device.
• When electric current is sent through a wire, a circular magnetic field appears around the cable.
• On a coil of wire that is not receiving electric current directly, electric current will begin to flow from the first coil through the magnetic field, including the second coil, providing inductive coupling.

Transfer principles

Until recently, the magnetic resonance system CMRS, created in 2007 at the Massachusetts Institute of Technology, was considered the most advanced technology for transmitting electricity. This technology provided current transmission over a distance of up to 2.1 meters. However, several limitations prevented its launch into mass production, for example, high transmission frequency, large dimensions, complex coil configuration, as well as high sensitivity to external interference, including human presence.

However, scientists from South Korea have created a new electricity transmitter that will transmit energy up to 5 meters. And all devices in the room will be powered by a single hub. The resonant system of DCRS dipole coils is capable of operating up to 5 meters. The system does not have a number of disadvantages of CMRS, including the use of fairly compact coils measuring 10x20x300 cm, which can be discreetly installed in the walls of an apartment.

The experiment made it possible to transmit at a frequency of 20 kHz:

1. 209 W at 5 m;
2. 471 W at 4 m;
3. 1403 W at 3 m.

Wireless electricity allows you to power modern large LCD TVs, which require 40 W, at a distance of 5 meters. The only thing that will be “pumped out” from the electrical network is 400 watts, but there will be no wires. Electromagnetic induction provides high efficiency, but at a short distance.

There are other technologies that allow you to transmit electricity wirelessly. The most promising of them are:

• Laser radiation . Provides network security as well as greater range. However, line of sight between the receiver and transmitter is required. Operating installations using power from laser beam, have already been created. Lockheed Martin, an American manufacturer of military equipment and aircraft, tested the Stalker unmanned aerial vehicle, which is powered by a laser beam and remains in the air for 48 hours.
• Microwave radiation . Provides a long range, but has a high equipment cost. A radio antenna is used as a transmitter of electricity, which creates microwave radiation. The receiver device has a rectenna, which converts the received microwave radiation into electric current.

This technology makes it possible to significantly distance the receiver from the transmitter, and there is no direct need for line of sight. But with increasing range, the cost and size of the equipment increases proportionally. At the same time, microwave radiation high power, generated by installation, may be harmful to the environment.

Peculiarities

• The most realistic of the technologies is wireless electricity based on electromagnetic induction. But there are limitations. Work is underway to scale the technology, but health safety issues arise here.
• Technologies for transmitting electricity using ultrasound, laser and microwave radiation will also develop and will also find their niches.
• Orbiting satellites with huge solar panels require a different approach, requiring targeted transmission of electricity. Laser and microwave are appropriate here. On this moment No perfect solution, however, there are many options with their pros and cons.
• Currently, the largest manufacturers of telecommunications equipment have united in the Wireless Electromagnetic Energy Consortium to create a worldwide standard for wireless chargers that operate on the principle of electromagnetic induction. From large manufacturers Sony, Samsung, Nokia, Motorola Mobility, LG Electronics, Huawei, and HTC provide support for the QI standard on a number of their models. Soon QI will become a unified standard for any such devices. Thanks to this, it will be possible to create wireless charging zones for gadgets in cafes, transport hubs and other public places.

Application

• Microwave helicopter. The helicopter model had a rectenna and rose to a height of 15 m.
• Wireless electricity is used to power electric toothbrushes. The toothbrush has a completely sealed body and has no connectors, which avoids electric shock.
• Powering aircraft using lasers.
• Wireless charging systems are now available for sale mobile devices that can be used every day. They work on the basis of electromagnetic induction.
• Universal charging pad. They allow you to power most of the popular models smartphones that are not equipped with a wireless charging module, including regular phones. In addition to the charging pad itself, you will need to buy a receiver case for the gadget. It connects to a smartphone via a USB port and is charged through it.
• Currently, over 150 devices up to 5 Watts that support the QI standard are sold on the world market. In the future, equipment with average power up to 120 Watt will appear.

Prospects

Today we are working on large projects, which will use wireless electricity. This is power supply for electric vehicles “over the air” and household electrical networks:

• A dense network of car charging points will make it possible to reduce batteries and significantly reduce the cost of electric vehicles.
• Power supplies will be installed in each room, which will transmit electricity to audio and video equipment, gadgets and household appliances equipped with appropriate adapters.

Advantages and disadvantages

Wireless electricity has the following advantages:

• No power supplies required.
• Complete absence of wires.
• Eliminate the need for batteries.
• Less maintenance required.
• Huge prospects.

Disadvantages also include:

• Insufficient technology development.
• Limited by distance.
• Magnetic fields are not completely safe for humans.
• High cost of equipment.

When Apple company introduced its first wireless charger for cell phones and gadgets, many considered it a revolution and a huge leap forward in wireless energy transfer methods.

But were they pioneers, or even before them, did someone manage to do something similar, albeit without proper marketing and PR? It turns out there were, and a very long time ago, and there were many such inventors.

So back in 1893, the famous Nikola Tesla demonstrated a glow to the amazed public fluorescent lamps. Despite the fact that they were all wireless.

Now any schoolchild can repeat this trick by going out into an open field and standing under the line with a fluorescent lamp high voltage from 220kv and above.

A little later, Tesla managed to light a phosphorus incandescent light bulb in the same wireless way.

In Russia in 1895, A. Popov showed the world's first radio receiver in operation. But by and large, this is also a wireless transfer of energy.

The most important question and at the same time the problem of the entire technology of wireless charging and similar methods lies in two points:

• how far can electricity be transmitted this way?

• and what quantity

First, let's figure out what power the devices have and Appliances those around us. For example, a phone, smartwatch or tablet requires a maximum of 10-12W.

The laptop already has higher demands - 60-80W. This can be compared to the average incandescent light bulb. But household appliances, especially kitchen appliances, already consume several thousand watts.

Therefore, it is very important not to skimp on the number of outlets in the kitchen.

So what methods and methods for transmitting electrical energy without the use of cables or any other conductors has mankind come up with over all these years? And most importantly, why are they still not implemented as actively into our lives as we would like?

Take the same kitchen appliances. Let's take a closer look.

Transferring energy through coils

The most easily implemented method is to use inductors.

The principle here is very simple. Take 2 coils and place them close to each other. One of them is supplied with power. The other plays the role of receiver.

When the current in the power source is adjusted or changed, the magnetic flux in the second coil automatically changes as well. As the laws of physics say, in this case an EMF will arise and it will directly depend on the rate of change of this flow.

It would seem that everything is simple. But the shortcomings spoil the whole rosy picture. Three disadvantages:

• low power

Using this method, you will not transfer large volumes and will not be able to connect powerful devices. If you try to do this, you will simply melt all the windings.

• short distance

Don't even think about transmitting electricity over tens or hundreds of meters here. This method has limited effect.

To physically understand how bad things are, take two magnets and figure out how far apart they need to be before they stop attracting or repelling each other. The efficiency of coils is approximately the same.

You can, of course, get creative and ensure that these two elements are always close to each other. For example, an electric car and a special charging road.

But how much will the construction of such highways cost?

• low efficiency

Another problem is low efficiency. It does not exceed 40%. It turns out that you will not be able to transmit a lot of electrical energy over long distances in this way.

The same N. Tesla pointed out this back in 1899. Later he switched to experiments with atmospheric electricity, hoping to find in it a solution and a solution to the problem.

However, no matter how useless all these things may seem, with their help you can still organize beautiful light and music performances.

Or recharge equipment much larger than phones. For example electric bicycles.

Laser energy transfer

But how can more energy be transferred to longer distance? Think about which films we see such technology very often.

The first thing that comes to mind even for a schoolboy is " star Wars", lasers and lightsabers.

Of course, with their help you can convey a large number of electricity over very long distances. But again everything is spoiled by a small problem.

Fortunately for us, but unfortunately for the laser, the Earth has an atmosphere. And it just does a good job of jamming and eating up most of the total energy of laser radiation. Therefore, with this technology we need to go into space.

There have also been attempts and experiments on Earth to test the functionality of the method. Nasa even held a competition on laser wireless energy transfer with a prize fund of just under $1 million.

In the end, Laser Motive won. Their winning result is 1 km and 0.5 kW of transmitted continuous power. However, during the transfer process, scientists lost 90% of all the original energy.

But still, even with an efficiency of ten percent, the result was considered successful.

Let us remember that a simple light bulb has even less useful energy that goes directly into the light. Therefore, it is profitable to make infrared heaters from them.

Microwave

Is there really no other really working way to transmit electricity without wires? There is, and it was invented even before attempts and children's games in star wars.

It turns out that special microwaves with a length of 12 cm (frequency 2.45 GHz) are transparent to the atmosphere and it does not interfere with their propagation.

No matter how bad the weather, when transmitting using microwaves, you will only lose five percent! But to do this, you must first convert electric current into microwaves, then catch them and return them to their original state.

Scientists solved the first problem a long time ago. They invented a special device for this and called it a magnetron.

Moreover, this was done so professionally and safely that today each of you has such a device at home. Go into the kitchen and take a look at your microwave.

It has the same magnetron inside with an efficiency of 95%.

But how to do the reverse transformation? And here two approaches were developed:

• American

• Soviet

In the USA, back in the sixties, scientist W. Brown came up with an antenna that performed the required task. That is, it converted the radiation incident on it back into electric current.

He even gave it his own name - rectenna.

After the invention, experiments followed. And in 1975, with the help of a rectenna, as much as 30 kW of power was transmitted and received at a distance of more than one kilometer. Transmission losses were only 18%.

Almost half a century later, no one has been able to surpass this experience. It would seem that the method has been found, so why weren’t these rectennas released to the masses?

And here again the shortcomings emerge. Rectennas were assembled using miniature semiconductors. Normal operation for them it is the transfer of only a few watts of power.

And if you want to transfer tens or hundreds of kW, then get ready to assemble giant panels.

And this is where unsolvable difficulties arise. Firstly, this is re-emission.

Not only will you lose some of your energy because of it, but you will also not be able to get closer to the panels without losing your health.

The second headache is the instability of semiconductors in the panels. It is enough for one to burn out due to a small overload, and the rest fail like an avalanche, like matches.

In the USSR everything was somewhat different. It was not for nothing that our military was confident that even in the event of a nuclear explosion, all foreign equipment would immediately fail, but Soviet equipment would not. The whole secret is in the lamps.

At Moscow State University, two of our scientists, V. Savin and V. Vanke, designed the so-called cyclotron energy converter. It has decent dimensions, as it is assembled based on lamp technology.

Externally, it is something like a tube 40 cm long and 15 cm in diameter. The efficiency of this lamp unit is slightly less than that of the American semiconductor thing - up to 85%.

But unlike semiconductor detectors, a cyclotron energy converter has a number of significant advantages:

• reliability

• high power

• overload resistance

• no re-emission

• low manufacturing cost

However, despite all of the above, semiconductor methods of project implementation are considered advanced all over the world. There is also an element of fashion here.

After the first appearance of semiconductors, everyone abruptly began to abandon tube technologies. But practical tests suggest that this is often the wrong approach.

Of course, lamp Cell Phones 20 kg each or computers that occupy entire rooms are of no interest to anyone.

But sometimes only proven old methods can help us out in hopeless situations.

As a result, today we have three opportunities to transmit energy wirelessly. The very first one discussed is limited by both distance and power.

But this is quite enough to charge the battery of a smartphone, tablet or something larger. The efficiency, although small, is still a working method.

The first of them started out very encouragingly. In the 2000s, on Reunion Island, there was a need for permanent transfer 10 kW of power at a distance of 1 km.

The mountainous terrain and local vegetation did not allow the laying of overhead power lines or cables there.

All movements on the island to this point were carried out exclusively by helicopters.

To solve the problem, the best minds from different countries were gathered into one team. Including those previously mentioned in the article, our scientists from Moscow State University V. Vanke and V. Savin.

However, at the moment when the practical implementation and construction of energy transmitters and receivers should have begun, the project was frozen and stopped. And with the onset of the crisis in 2008, they completely abandoned it.

In fact, this is very disappointing, since the theoretical work done there was colossal and worthy of implementation.

The second project looks crazier than the first. However, real funds are allocated for it. The idea itself was expressed back in 1968 by US physicist P. Glaser.

He proposed a not entirely normal idea at that time - to launch a huge satellite into geostationary orbit 36,000 km above the earth. Place it on it solar panels, which will collect free energy from the sun.

Then all this should be converted into a beam of microwave waves and transmitted to the ground.

A sort of “death star” in our earthly realities.

On the ground, the beam must be caught by giant antennas and converted into electricity.

How big do these antennas need to be? Imagine that if the satellite is 1 km in diameter, then the receiver on the ground should be 5 times larger - 5 km (the size of the Garden Ring).

But size is only a small part of the problem. After all the calculations, it turned out that such a satellite would generate electricity with a capacity of 5 GW. When reaching the ground there would be only 2GW left. For example, the Krasnoyarsk hydroelectric power station produces 6 GW.

Therefore, his idea was considered, calculated and put aside, since everything initially came down to price. The cost of the space project in those days reached $1 trillion.

But science, fortunately, does not stand still. Technologies are improving and becoming cheaper. Several countries are already developing such a solar space station. Although at the beginning of the twentieth century, only one brilliant person was enough for wireless transmission of electricity.

The total price of the project dropped from the original to $25 billion. The question remains - will we see its implementation in the near future?

Unfortunately, no one will give you a clear answer. Bets are placed only on the second half of this century. Therefore, for now, let's be content with wireless chargers for smartphones and hope that scientists will be able to increase their efficiency. Well, or in the end, a second Nikola Tesla will be born on Earth.

Everyone knows that Nikola Tesla is the inventor of such ubiquitous things as alternating current and the transformer. But not all scientists are familiar with Tesla’s other inventions.

We use alternating current. We use transformers. In any apartment. It is difficult to imagine how one can do without these inventions. But HOW do we use them? Tesla used these things known to us (as it seems to us) in a completely different way. How do we connect any electrical appliance to the network? With a fork - i.e. two conductors. If we connect only one conductor, there will be no current - the circuit is not closed.

Tesla demonstrated the effect of transmitting power through a single conductor. Moreover, in other experiments it transmitted power without wires at all. At the end of the 19th century, the great inventor was able to transmit electrical energy wirelessly over a distance of over 40 kilometers. Since this well-known Tesla experiment has not yet been repeated, our readers will certainly be interested in the details of this story, as well as current state problems of transmitting electrical energy without wires.

The biography of the American inventor, Serbian by birth, Nikola Tesla is quite well known, and we will not dwell on it. But let’s immediately clarify: before demonstrating his unique experiment, Tesla, first in 1892 in London, and a year later in Philadelphia, in the presence of specialists, demonstrated the possibility of transmitting electrical energy through one wire, without using grounding of the second pole of the energy source.

And then he had the idea to use the Earth as this only wire! And that same year, at the Electric Lighting Association convention in St. Lewis, he demonstrated electric lamps, burning without supply wires, and an electric motor operating without being connected to the electrical network. He commented on this unusual exhibition as follows: “A few words about an idea that constantly occupies my thoughts and concerns us all. I mean transmitting signals, as well as energy, over any distance without wires. We already know that electrical vibrations can be transmitted through a single conductor. Why not use the Earth for this purpose? If we can determine the period of oscillation electric charge Earth, with its disturbance associated with the action of an oppositely charged circuit, this will be a fact of extreme importance, which will serve for the benefit of all mankind.”

Seeing such a spectacular demonstration, such famous oligarchs as J. Westinghouse and J. P. Morgan invested over a million dollars in this promising business, buying his patents from Tesla (huge money, by the way, at that time!). With these funds, in the late 90s of the 19th century, Tesla built his unique laboratory in Colorado Springs. Detailed information about the experiments in Tesla’s laboratory is presented in the book of his biographer John O’Neill, “Electric Prometheus” (in our country, its translation was published in the magazine “Inventor and Innovator” No. 4-11 for 1979). We will give here only a brief excerpt from it, so as not to refer to later reprints: “In Colorado Springs, Tesla conducted the first tests of wireless transmission of electricity. He was able to power 200 light bulbs incandescent, located 42 kilometers from his laboratory. Each power was 50 watts, so the total energy consumption was 10 kW, or 13 hp. Tesla was convinced that with the help of a more powerful vibrator he could light a dozen electric garlands of 200 light bulbs each, scattered around the globe."

Tesla himself was so inspired by the success of these experiments that he announced in the general press that he intended to illuminate the World Industrial Exhibition in Paris, which was supposed to be held in 1903, with energy from a power plant located at Niagara Falls and transmitted to Paris wirelessly. It is known from numerous photographs and descriptions of eyewitnesses and assistants of the inventor that it was a generator of energy transmitted over 42 kilometers without wires (however, this is a purely journalistic term: one wire, which was the Earth, is present in this circuit, and this is directly stated both Tesla himself and his biographer).

What Tesla called a vibrator was a giant transformer of his system, which had a primary winding of several turns of thick wire wound on a fence with a diameter of 25 meters, and a multi-turn single-layer secondary winding placed inside it on a cylinder of dielectric. Primary winding together with a capacitor, an induction coil and a spark gap it formed an oscillatory circuit-frequency converter. Above the transformer, located in the center of the laboratory, rose a wooden tower 60 meters high, topped with a large copper ball. One end of the secondary winding of the transformer was connected to this ball, the other was grounded. The entire device was powered by a separate 300 hp dynamo. He was excited electromagnetic vibrations frequency 150 kilohertz (wavelength 2000 meters). Operating voltage in the high-voltage circuit was 30,000 V, and the resonating potential of the ball reached 100,000,000 V, generating artificial lightning tens of meters long! This is how his biographer explains the work of Tesla’s vibrator: “In essence, Tesla “pumped” a stream of electrons into the Earth and extracted from there. The pumping frequency was 150 kHz. Spreading in concentric circles further and further from Colorado Springs, the electric waves then converged at a diametrically opposite point on the Earth. Large amplitude waves rose and fell there in unison with those raised in Colorado. When such a wave fell, it sent an electric echo back to Colorado, where an electric vibrator amplified the wave, and it rushed back.

If we bring the entire Earth into a state of electrical vibration, then at every point on its surface we will be provided with energy. It will be possible to capture it from the waves rushing between the electric poles simple devices like oscillatory circuits in radios, only grounded and equipped with small antennas the height of a rural cottage. This energy will heat and light homes using Tesla's tubular lamps, which require no wires. AC motors would only require frequency converters.”

Information about Tesla's experiments on transmitting electricity without wires inspired other researchers to work in this area. Reports of similar experiments often appeared in the press at the beginning of the last century. In this regard, it is worth citing an excerpt from an article by A.M. Gorky’s “Conversations on Craft,” published in 1930: “This year, Marconi transmitted electric current by air from Genoa to Australia and lit electric lamps there at an exhibition in Sydney. The same thing was done 27 years ago here, in Russia, by the writer and scientist M.M. Filippov, who worked for several years on transmitting electric current through the air and eventually lit a chandelier from St. Petersburg in Tsarskoe Selo ( that is, at a distance of 27 kilometers. -V.P.). At that time, no due attention was paid to this fact, but Filippov was found dead in his apartment a few days later, and his devices and papers were confiscated by the police.”

Tesla's experiments also made a great impression on another writer, Alexei Tolstoy, who was an engineer by training. And when Tesla, and then Marconi, reported in print that their devices were receiving strange signals of extraterrestrial, apparently Martian origin, this inspired the writer to write the science fiction novel “Aelita.” In the novel, the Martians use Tesla's invention and wirelessly transmit energy from power plants located at the poles of Mars to anywhere on the planet. This energy powers the engines of flying ships and other mechanisms. However, to build your own “world system” to provide electricity to the population globe Tesla failed without the use of wires.

As soon as in 1900 he began to build a research laboratory town for 2000 employees and a huge metal tower with a giant copper plate on top on the island of Long Island near New York, the “wired” electrical oligarchs realized it: after all, the widespread introduction of Tesla’s system threatened them with ruin.

Wardenclyffe Tower (1902)

On billionaire J.P. Morgan, who financed the construction, was subject to severe pressure, including from government officials bribed by competitors.(or it was the other way around) There were interruptions in the supply of equipment, construction stalled, and when Morgan, under this pressure, stopped funding, it stopped altogether. At the beginning of the First World War, at the instigation of the same competitors, the US government ordered the explosion of a ready-made tower under the far-fetched pretext that it could be used for espionage purposes.

Well, then electrical engineering went the usual way.

For a long time, no one could repeat Tesla’s experiments, if only because it would have been necessary to create an installation similar in size and power. But no one doubted that Tesla managed to find a way to transmit electrical energy over a distance without wires more than a hundred years ago. The authority of Tesla, who was rated as the second inventor after Edison, was quite high throughout the world, and his contribution to the development of alternating current electrical engineering (in defiance of Edison, who advocated D.C.) is certain. During his experiments, many specialists were present, not counting the press, and no one ever tried to convict him of any tricks or manipulation of facts. The high authority of Tesla is evidenced by the name of the unit of tension after him. magnetic field. But Tesla’s conclusion that during the experiment in Colorado Springs energy was transmitted over a distance of 42 kilometers with an efficiency of about 90% is too optimistic. Let us recall that the total power of the lamps lit at a distance was 10 kW, or 13 hp, while the power of the dynamo that powered the vibrator reached 300 hp. That is, we can talk about efficiency. only about 4-5%, although this figure is amazing. The physical justification of Tesla's experiments on wireless transmission of electricity still worries many specialists.
www.elec.ru/news/2003/03/14/1047627665.h tml

Specialists from the Massachusetts Institute of Technology managed to make an incandescent lamp burn, located at a distance of 2 meters from the energy source. rus.newsru.ua/world/08jun2007/tesla.html

Wireless chargers from Intel odessabuy.com/news/item-402.html

"Arguments and Facts" No. 52, 2008 (December 24-30):
SCIENCE - Electricity without wires. They say that American scientists were able to transmit electricity with a power of 800 W without wires.