Do-it-yourself magnetic levitation using a simple scheme. DIY electromagnetic levitation device Levitron at home
Materials for making Levitron
So, to make a toy, we need three ring-shaped magnets with sufficient power. Magnets from low-frequency speakers whose service life has long expired are quite suitable for our purpose.In order to make a top, you will need a neodymium magnet. You can take it from the speaker, which has the inscription “Neodium transducer”. Similar speakers are used in cell phones. The strongest permanent magnet today is neodymium, created from an alloy that includes neodymium, boron and iron. High temperature will negatively affect it, so this magnet should be protected from heat. So, a magnet from a cell phone can be of two types - in the form of a round plate or in the form of a ring. The ring magnet is placed on the top itself strictly in the center, and the tablet-shaped magnet is glued to the axis of the top from below. The material for the top itself should be a lightweight material such as composite or plastic.
Setting up Levitron
The setup should be approached with particular scrupulousness, because this part of the work is crucial and is the most labor-intensive. Ring magnets must be connected to each other with opposite polarities. A plate (not made of metal) up to 1 cm thick should be installed on top of them. The top will be carefully installed at the base of the Levitron - the center of the magnet. If you notice that the top deviates to the side, then the magnet needs to be replaced with another one with a larger diameter.To launch the top, you will need several more elements with which you can adjust the thickness of the platform in order to achieve normal rotation of the top. We will need plexiglass plastic with paper sheets. If the top is spinning normally, we begin to smoothly raise the platform until it flies up.
If our top flies up too quickly, its weight should be increased. If it deviates in one direction, then the situation can be corrected by placing paper sheets under the opposite direction. These steps allow us to adjust the base of our toy so that it is clearly at sea level.
And a video with Levitrons...
I read all sorts of things on the Internet and decided to build my own Levitron, without any digital nonsense. No sooner said than done. I post the pains of creativity for everyone to see.1. Brief description
Levitron is a device that keeps an object in balance with the forces of gravity using a magnetic field. It has long been known that it is impossible to levitate an object using static magnetic fields. In school physics this was called a state of unstable equilibrium, as far as I remember. However, with a little desire, knowledge, effort, money and time, it is possible to levitate an object dynamically by using electronics as feedback.This is what happened:
2.Functional diagram
Electromagnetic sensors located at the ends of the coil produce a voltage proportional to the level of magnetic induction. In the absence of an external magnetic field, these voltages will be the same regardless of the magnitude of the coil current.
If there is a permanent magnet near the lower sensor, the control unit will generate a signal proportional to the magnet field, amplify it to the desired level and transmit it to PWM to control the current through the coil. Thus, feedback occurs and the coil will generate a magnetic field that will keep the magnet in balance with the forces of gravity.
Something went wrong, I’ll try it differently:
- There is no magnet - the induction at the ends of the coil is the same - the signal from the sensors is the same - the control unit produces a minimum signal - the coil works at full power;
- They brought a magnet close - the induction is very different - the signals from the sensors are very different - the control unit produces the maximum signal - the coil turns off completely - no one is holding the magnet and it begins to fall;
- The beckoning falls - moves away from the coil - the difference in signals from the sensors decreases - the control unit reduces the output signal - the current through the coil increases - the induction of the coil increases - the magnet begins to attract;
- The magnet is attracted - it approaches the coil - the difference in signals from the sensors increases - the control unit increases the output signal - the current through the coil decreases - the induction of the coil decreases - the magnet begins to fall;
- It’s a miracle - the magnet does not fall and is not attracted - or rather, it falls and is attracted several thousand times per second - that is, dynamic equilibrium arises - the magnet simply hangs in the air.
3.Design
The main element of the design is an electromagnetic coil (solenoid), which holds a permanent magnet with its field.78 meters of enameled copper wire with a diameter of 0.6 mm are tightly wound onto a plastic frame D36x48, about 600 turns. According to calculations, with a resistance of 4.8 Ohm and a power supply of 12V, the current will be 2.5A, power 30W. This is necessary to select an external power supply. (In fact, it turned out to be 6.0 Ohm; it’s unlikely that they cut more wire, but rather saved on the diameter.)
A steel core from a door hinge with a diameter of 20mm is inserted inside the coil. Sensors are attached to its ends using hot-melt adhesive, which must be oriented in the same direction.
The coil with sensors is mounted on a bracket made of aluminum strip, which, in turn, is attached to the housing, inside of which there is a control board.
On the case there is an LED, a switch and a power socket.
The external power supply (GA-1040U) is taken with a power reserve and provides a current of up to 3.2A at 12V.
An N35H magnet D15x5 with a Coca-Cola can glued on is used as a levitating object. I’ll say right away that a full jar is not good, so we make holes at the ends with a thin drill, drain the valuable drink (you can drink it if you’re not afraid of shavings) and glue a magnet to the top ring.
4.Schematic diagram
Signals from sensors U1 and U2 are fed to the operational amplifier OP1/4, connected in a differential circuit. The upper sensor U1 is connected to the inverting input, the lower U2 is connected to the non-inverting input, that is, the signals are subtracted, and at the output OP1/4 we obtain a voltage proportional only to the level of magnetic induction created by the permanent magnet near the lower sensor U2.
The combination of elements C1, R6 and R7 is the highlight of this circuit and allows you to achieve the effect of complete stability; the magnet will hang rooted to the spot. How it works? The DC component of the signal passes through the divider R6R7 and is attenuated 11 times. The variable component passes through the C1R7 filter without attenuation. Where does the variable component come from anyway? The constant part depends on the position of the magnet near the lower sensor, the variable part arises due to oscillations of the magnet around the equilibrium point, i.e. from changes in position in time, i.e. from speed. We are interested in the magnet being stationary, i.e. its speed was equal to 0. Thus, in the control signal we have two components - the constant is responsible for the position, and the variable is for the stability of this position.
Next, the prepared signal is amplified at OP1/3. Using variable resistor P2, the required gain is set at the tuning stage to achieve equilibrium, depending on the specific parameters of the magnet and coil.
A simple comparator is assembled on OP1/1, which turns off the PWM and, accordingly, the coil when there is no magnet nearby. A very convenient thing, you don’t need to remove the power supply from the outlet if you remove the magnet. The response level is set by variable resistor P1.
Next, the control signal is supplied to the pulse-width modulator U3. The output voltage swing is 12V, the output pulse frequency is set by the values of C2, R10 and P3, and the duty cycle depends on the input signal level at the DTC input.
PWM controls the switching of power transistor T1, which, in turn, controls the current through the coil.
The LED1 LED may not be installed, but the SD1 diode is required to drain excess current and avoid overvoltage when the coil is turned off due to the phenomenon of self-induction.
NL1 is our homemade coil, which has a separate section dedicated to it.
As a result, in equilibrium mode, the picture will be something like this: U1_OUT=2.9V, U2_OUT=3.6V, OP1/4_OUT=0.7V, U3_IN=1.8V, T1_OPEN=25%, NL1_CURR=0.5A.
For clarity, I am attaching graphs of the transfer characteristic, frequency response and phase response, and oscillograms at the output of the PWM and coil.
5.Selection of components
The device is assembled from inexpensive and accessible components. The most expensive copper wire turned out to be WIK06N; for 78 meters WIK06N paid 1,200 rubles; everything else taken together was much cheaper. There is generally a wide field for experimentation; you can do without a core, you can take thinner wire. The main thing is not to forget that the induction along the axis of the coil depends on the number of turns, the current through them and the geometry of the coil.Analog Hall sensors SS496A with a linear characteristic up to 840G are used as magnetic field sensors U1 and U2, this is just right for our case. When using analogues with a different sensitivity, you will need to adjust the gain at OP1/3, as well as check the level of maximum induction at the ends of your coil (in our case with a core it reaches 500G) so that the sensors do not become saturated at peak load.
OP1 is an LM324N quad operational amplifier. When the coil is turned off, it produces 20 mV instead of zero at output 14, but this is quite acceptable. The main thing is not to forget to choose from a bunch of 100K resistors those closest in actual value to install as R1, R2, R3, R4.
The values C1, R6 and R7 were selected through trial and error as the most optimal option for stabilizing magnets of different calibers (N35H magnets D27x8, D15x5 and D12x3 were tested). The R6/R7 ratio can be left as it is, and the value of C1 can be increased to 2-5 µF if problems arise.
If you use very small magnets, you may not have enough gain, in which case reduce the value of R8 to 500 ohms.
D1 and D2 are ordinary 1N4001 rectifier diodes, any will do.
The common TL494CN chip is used as a pulse-width modulator U3. The operating frequency is set by elements C2, R10 and P3 (according to the 20 kHz scheme). The optimal range is 20-30 kHz, at lower frequencies the coil whistle appears. Instead of R10 and P3, you can simply put a 5.6K resistor.
T1 is an IRFZ44N field-effect transistor; any other one from the same series will do. When choosing other transistors, you may need to install a radiator; be guided by the minimum values of channel resistance and gate charge.
SD1 is a Schottky diode VS-25CTQ045, here I grabbed it with a large margin, a regular high-speed diode will do, but it will probably get very hot.
LED1 yellow LED L-63YT, here, as they say, it depends on taste and color, you can set them more so that everything glows with multi-colored lights.
U4 is a 5V L78L05ACZ voltage regulator for powering the sensors and operational amplifier. When using an external power supply with an additional 5V output, you can do without it, but it is better to leave the capacitors.
6.Conclusion
Everything worked out as planned. The device operates stably around the clock and consumes only 6W. Neither the diode, nor the coil, nor the transistor gets hot. I'm attaching a couple more photos and the final video:
7. Disclaimer
I'm not an electronics engineer or a writer, I just decided to share my experience. Maybe something will seem too obvious to you, something too complicated, and something you forgot to mention at all. Feel free to make constructive suggestions both on the text and on improving the diagram, so that people can easily repeat it if they so desire.Today, technological progress has reached such a level that it has allowed scientists to come close to solving the problem of creating a train track on magnetic suspended elements. They will travel without contacting metal tracks, but at some distance from them. The whole “trick” is built on magnetic levitation in the air, allowing the train to seem to float in space.
Scientific interpretation
Many people believe that levitation in a magnetic field is the free path of a magnet thrown in space. In fact, this physical process consists of overcoming the forces of gravity by an object under the influence of a magnet. The magnetic pressure of the magnetic field is exerted on it. In ordinary language, by magnetic levitation in space, we must understand that if a lying object is subject to gravitational pressure from top to bottom, then a reverse force can be created that can neutralize the attraction. That is, the object levitates in the air.
In order to better understand magnetic levitation in the air, you need to remember your school physics curriculum. If you take two magnets and bring their north poles closer to each other, they will repel. When you bring the north pole closer to the south side, the magnets will be attracted. The first experiment allows objects with enormous weight to levitate in space.
The concept of diamagnetic levitation
In physics, diamagnetic levitation is the neutralization of the magnetic pressure of a magnetic field from any object or object. From many DIY experiments, it becomes clear that diamagnetism makes objects weightless in space. Moreover, such a process can occur in an environment with different temperatures and with objects having different weights.
An example of this would be the experiment with a frog levitating in the air. The animal was placed in a created magnetic field with an induction of more than 16 Tesla, and everyone saw a floating frog.
In addition, you can create a magnetic field with an induction of 11 Tesla and place your hands in the created field. Due to this, the magnet will begin to float in the air. Moreover, the flight of the magnet is easy to control. How to do this trick? You need to lightly touch the magnet with your hand, and it will always be between your hands. The fingers will be diamagnetic.
In the service of man
In practice, magnetic levitation in the air with a person has already been proven by scientists. On today's agenda is the task of applying the process with technical means that are in the service of civilization.
Flying trains
In scientific developments, such trains are called maglevs (the first part of the word is magnetic, the second part is levitation). Today they work quite successfully transporting passengers in Japan. But even there, due to significant financial investments, they occupy a small percentage of the total railway fleet.
It is important to know! Such railway transport moves using a magnetic field created by powerful magnetic elements that are mounted under the railway track.
Trains of this principle of operation are capable of developing high speeds due to the elimination of friction. That is, due to magnetic levitation in the air, they do not come into contact with metal slats.
Wear-free mechanics
The second area of application of this phenomenon is mechanics. Many experts are aware of the short service life of ball bearings in mechanical components, leading to serious accidents and long downtime of production lines.
Today, in practice, this problem is solved using a magnetic field. Scientists have developed magnetic bearings. They are especially used in places that are difficult to access for repairs.
In addition, magnetic bearings are used in components of vertical wind generators. This makes it possible to convert wind energy into electricity without costly maintenance or downtime.
As a result, it should be noted that many processes previously described by man in works of the science fiction genre are becoming reality. The human mind will soon be able to realize ideas with plasma windows, laser curtains and carbon computers.
Video
As you know, the Earth, due to the current world order, has a certain, and man’s dream has always been to overcome it by any means. Magnetic levitation is a more fantastic term than one that relates to everyday reality.
Initially, it meant the hypothetical ability to somehow overcome gravity and move people or objects through the air without auxiliary equipment. However, now the concept of “magnetic levitation” is already quite scientific.
Several innovative ideas are being developed at once, which are based on this phenomenon. And all of them promise excellent opportunities for versatile applications in the future. True, magnetic levitation will not be carried out using magical techniques, but using very specific achievements of physics, namely the section that studies magnetic fields and everything connected with them.
Just a little theory
Among people far from science, there is an opinion that magnetic levitation is the guided flight of a magnet. In fact, this term means overcoming gravity by an object using a magnetic field. One of its characteristics is magnetic pressure, which is used to “fight” gravity.
Simply put, when gravity pulls an object down, magnetic pressure is directed so that it pushes it in the opposite direction - up. This is how magnet levitation occurs. The difficulty in implementing the theory is that the static field is unstable and does not focus at a given point, so it may not be able to effectively resist gravity. Therefore, auxiliary elements are required that will give the magnetic field dynamic stability so that levitation of the magnet is a regular phenomenon. Various techniques are used as stabilizers. Most often - electric current through superconductors, but there are other developments in this area.
Technical levitation
Actually, the magnetic variety refers to a broader term for overcoming gravitational attraction. So, technical levitation: a review of methods (very brief).
We seem to have figured out a little with magnetic technology, but there is also an electrical method. Unlike the first, the second can be used to manipulate products made from a variety of materials (in the first case, only magnetized ones), even dielectrics. Electrostatic and electrodynamic levitation are also distinguished.
The ability of particles to move under the influence of light was predicted by Kepler. And the existence was proven by Lebedev. The movement of a particle in the direction of the light source (optical levitation) is called positive photophoresis, and in the opposite direction - negative.
Aerodynamic levitation, different from optical, is quite widely applicable in modern technologies. By the way, “pillow” is one of its varieties. The simplest air cushion is obtained very easily - many holes are drilled in the carrier substrate and compressed air is blown through them. In this case, the air lift balances the mass of the object, and it floats in the air.
The latest method currently known to science is levitation using acoustic waves.
What are some examples of magnetic levitation?
Science fiction writers dreamed of portable devices the size of a backpack that could “levitate” a person in the direction he needed at considerable speed. Science has so far taken a different path, more practical and feasible - a train was created that moves using magnetic levitation.
History of super trains
The idea of a composition using a linear motor was first proposed (and even patented) by the German engineer-inventor Alfred Zein. And this was in 1902. After this, developments of an electromagnetic suspension and a train equipped with it appeared with enviable regularity: in 1906, Franklin Scott Smith proposed another prototype, between 1937 and 1941. Herman Kemper received a number of patents on the same topic, and a little later the Briton Eric Lazewaite created a working prototype of a full-size engine. In the 60s, he also participated in the development of Tracked Hovercraft, which was supposed to become the most, but never became, because due to insufficient funding, the project was closed in 1973.
Only six years later, again in Germany, a magnetic levitation train was built and licensed for passenger transportation. The test track, laid in Hamburg, was less than a kilometer long, but the idea itself inspired the public so much that the train operated even after the exhibition closed, having managed to transport 50 thousand people in three months. Its speed, by modern standards, was not so high - only 75 km/h.
Not a showpiece, but a commercial maglev (as the magnet-powered train was dubbed), had been running between Birmingham Airport and the railway station since 1984, and remained in service for 11 years. The length of the track was even shorter, only 600 m, and the train rose 1.5 cm above the track.
Japanese version
Subsequently, the excitement about magnetic levitation trains in Europe subsided. But by the end of the 90s, such a high-tech country as Japan became actively interested in them. Several rather long routes have already been laid on its territory, along which maglevs fly, using such a phenomenon as magnetic levitation. The same country also holds the speed records set by these trains. The last of them showed a speed limit of more than 550 km/h.
Further prospects for use
On the one hand, maglevs are attractive for their rapid movement capabilities: according to theorists, they can be accelerated to 1,000 kilometers per hour in the near future. After all, they are driven by magnetic levitation, and are only slowed down by air resistance. Therefore, giving the composition the most aerodynamic outlines possible greatly reduces its impact. In addition, due to the fact that they do not touch the rails, wear on such trains is extremely slow, which is very economically beneficial.
Another plus is the reduction in noise effect: maglevs move almost silently compared to conventional trains. A bonus is also the use of electricity in them, which reduces the harmful impact on nature and the atmosphere. In addition, it is able to overcome steeper slopes, which eliminates the need to lay railway tracks around hills and slopes.
Energy Applications
An equally interesting practical direction can be considered the widespread use of magnetic bearings in key components of mechanisms. Their installation solves the serious problem of wear of the source material.
As you know, classic bearings wear out quite quickly - they constantly experience high mechanical loads. In some areas, the need to replace these parts not only means additional expense, but also a high risk for the people who maintain the machine. remain operational many times longer, so their use is very advisable for any extreme conditions. In particular, in nuclear energy, wind technologies or industries accompanied by extremely low/high temperatures.
Aircrafts
The problem of how to implement magnetic levitation begs a reasonable question: when will a full-fledged aircraft in which magnetic levitation be used finally be manufactured and presented to progressive humanity? After all, there is indirect evidence that such “UFOs” existed. Take, for example, the Indian “vimanas” of the most ancient era or Hitler’s “disc planes”, which are closer to us in time, using, among other things, electromagnetic methods of organizing lifting force. Approximate drawings and even photos of working models have been preserved. The question remains open: how to bring all these ideas to life? But modern inventors have not yet gone beyond the not very viable prototypes. Or maybe this is still too secret information?
The simplest and most obvious example of magnetic levitation, which is created on permanent magnets, is the so-called levitron. This toy was invented by an American inventor almost 30 years ago. The design is based on only two ring magnets. The big one lies strictly horizontally, and the small one rotates and hovers above it. What keeps him from falling? How is this effect achieved? In the video, Igor Beletsky expresses ideas for the practical implementation of Levitron and conducts experiments.
Naturally, permanent magnets are directed towards each other with like poles, which causes them to repel. But this is not enough for sustainability. The large ring magnet creates a special form of magnetic field. In other words, a magnetic cavity or potentially a hole is formed, at the bottom of which the top finds its stability. But this only prevents him from falling to the sides.
The decisive factor for stable levitation is the rotation of the top itself, as a result of which a gyroscopic effect occurs, thanks to which the top does not tip over, although it constantly strives to do so, and as soon as friction and air slow down its rotation, the force of magnetic attraction will take over.
It would be tempting to find a practical use for such a gimbal. For example, make a contactless flywheel - an energy storage device. But the trouble is that according to the Levitron scheme, when a large magnet holds a small one, it is impossible to suspend a massive body. The repulsion force is extremely small - a measly 30 grams. This is the limit. Load more and the system will collapse, but increasing the size of the magnet is impractical and expensive. But how can this be? Neodymium magnets have a simply monstrous repulsive force, and this is true.
Magnets are sold cheaper in this Chinese store.
The author of the video, Igor Beletsky, tried to implement dynamic levitation using the principle of magnetic suspension, placing the axis of rotation vertically. The weight of the flywheel is easily compensated by two small ring magnets, but axial stabilization should have been provided by small magnets at the ends of the axis. Plus the gyroscopic effect from the rotation of the flywheel itself. Unfortunately, after conducting many experiments, he never achieved what he wanted. Perhaps he again chose not the most successful scheme, because the more magnets, and therefore voltages, in the system, the more difficult it is to balance it.
The simplest and cheapest method of magnetic suspension was proposed by professor of mechanics Nurbey Gulia. He simply transferred the entire mass of the flywheel to ring magnets, and left axial stabilization behind ordinary bearings, which is quite logical, because with a vertical axis of rotation, the load on them is minimal, as are friction losses. This, of course, is not pure levitation, but something very close. The author of the video quickly assembled a similar design and was convinced of its practicality. Instead of bearings, he used graphite bushings to stabilize the axle. Their friction is really minimal. Now if only we could put everything in an airless capsule and we would get a real storage device for mechanical energy. And then, for complete happiness, it would be logical to make contactless power take-off. The easiest way is to turn the flywheel into a magnetic rotor. For example, we add an inductor and get a generator, which, if necessary, can also work as an electric motor to spin up the drive flywheel. But that's a completely different story.
