Asked to give you New Year Anti-gravity Santa Claus should not answer "Mission Impossible". Hear such an answer, know - Grandfather is fake. Because scientific toys with anti-gravity elements exist and have been sold for $30-60 for several years.
There is a company in Seattle aptly named Fascinations Toys and Gifts. The charm of her products is that at first they seem unreal. True, unlike magicians, the creators of unusual souvenirs willingly reveal their secrets.
First of all, I would like to say about "Levitron" (Levitron). Before us is something like an ashtray (we will call it the base) over which a spinning top hangs in the air and spins. An anti-gravity device. Entertains "Levitron" as follows:
You take the included plate in your hand and hold it over the base. Place a spinning top on top of the plate and spin it strongly with your index and thumb.
Then the plate is slowly raised, then lowered and removed away - the gyroscope remains hanging in the air, rotating and swaying a little.
The thing is good, but practically useless on the farm (photo by hobbytron.net).
The toy does not require any electricity. Here, permanent magnets are used, placed both in the base and in the gyroscope.
From the point of view of classical physics, it is impossible to achieve the stability of two repulsive magnets, one of which floats on top of the other.
Specialists from Fascinations explain that they managed to find an exception to the rule.
More precisely, it was found by inventor Roy M. Harrigan and patented in May 1983.
As you guessed, the rotation keeps the top magnet from tipping over. But what prevents him from sliding sideways and flying off the magnetic cushion?
The lower magnet, and its field, respectively, has a complex shape. And when the top deviates from the center, a force arises that pushes it back to the equilibrium point.
It looks like "Levitron", made by hand (photo hcrs.at).
This force is very small and therefore the launch of Levitron will require training.
The balance in this system is so delicate that it is affected by the temperature in the room or even small fluctuations in the earth's magnetism.
The set of toys includes a set of 5 weights - weighing from 3 to 0.1 grams. Their combination achieves balance.
The adjustable legs of the base allow you to install it exactly horizontally, and besides, it is necessary to observe a certain orientation to the cardinal points.
Finally, the very process of lifting and removing the plate with a rotating gyroscope requires extreme caution. And the faster you can spin the top, the longer it will soar.
If the levitating top has captivated you enough, Seattle innovators are ready to offer you additional accessories for the Levitron.
For example, "Perpetuator" (Perpetuator), this time already connected to the outlet. Unlike the regular base, this one has added electromagnetic fields to keep the spinning top spinning so it can hang over your desk for weeks.
Other antigravity toy called Art Bank. This box, inside which a tennis ball, an airplane model, a coin or a candy wrapper, levitates.
In addition, there is a "flying globe" - Amazing Anti-Gravity Globes.
The anti-gravity globe is really a thing (photo fascinations.com).
Another “physical” creation of Fascinations is light and transparent waterfalls (Gosammer Falls). This is a whole collection of waterfalls, so to speak, for home and office.
They deserve mention because, unlike many analogues, they demonstrate an interesting effect.
Water flows in them in a wide and thin film, which never breaks, in any place. How is this possible?
Water, pouring out even from a thin extended gap, tends to gather into a more or less compact jet, and if this is not possible, it breaks into separate streams, breaks up into drops.
Magnetic levitation always looks impressive and bewitching. Such a device today can not only be bought, but also made by yourself. And in order to create such a magnetic levitation device, it is not necessary to spend a lot of money and time on it.
IN this material a diagram and instructions for assembling a magnetic levitator from inexpensive components will be presented. The assembly itself will take no more than two hours.
The idea of this device called Levitron is very simple. The electromagnetic force lifts a piece of magnetic material into the air, and in order to create a floating effect, the object rises and falls in a very small range of heights, but at a very high frequency.
To assemble a Levitron, you only need seven components, including a coil. The scheme of the magnetic levitation device is presented below.
So, as we see from the diagram, in addition to the coil, we need a field effect transistor, for example, an IRFZ44N or another similar MOSFET, a HER207 diode or something like 1n4007, 1KΩ and 330Ω resistors, an A3144 Hall sensor, and an optional indicator LED. The coil can be made independently, this will require 20 meters of wire with a diameter of 0.3-0.4 mm. To power the circuit, you can take a 5 V charger.
To make a coil, you need to take the base with the dimensions shown in the following figure. For our coil, it will be enough to wind 550 turns. Having finished winding, it is desirable to insulate the coil with some kind of electrical tape.
Now solder almost all the components except the Hall sensor and the coil on a small board. Place the Hall sensor in the hole of the coil.
Fix the coil so that it is above the surface at some distance. After that on this device magnetic levitation can be powered. Take a small piece of neodymium magnet and bring it to the bottom of the coil. If everything is done correctly, then the electromagnetic force will pick it up and keep it in the air.
If this device does not work properly for you, then check the sensor. Its sensitive part, that is, the flat side with the inscriptions, should be parallel to the ground. Also, for levitation, the shape of the tablet, which is inherent in most sold neodymium magnets, is not the most successful. So that the center of gravity does not “walk”, you need to transfer it to the bottom of the magnet, attaching something not too heavy, but not too light either. For example, you can add a piece of cardboard or thick paper like in the first picture.
Levitron is a toy that demonstrates the levitation of a spinning top, in which a neodymium magnet is located above a ferrite magnet of a larger diameter. It looks amazing!Materials for the manufacture of Levitron
So, we need three ring-shaped magnets with sufficient power to make a toy. 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. Strongest permanent magnet today it is neodymium, created from an alloy that includes neodymium, boron and iron. Heat will adversely affect it, so this magnet should be protected from heat. So the magnet 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 put 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.
Levitron setting
The setting should be approached with particular scrupulousness, because this part of the work is crucial and is the most time-consuming. Ring magnets must be connected to each other by 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 in 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 start the top, you will need a few 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 spinning top is spinning normally, we begin to gently raise the platform until it flies up.
If our spinning top flies up with excessive swiftness, its weight should be increased. If it deviates in one direction, then you can correct the situation by placing paper sheets under the opposite one. These actions allow you 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 Internet here and decided to build my own Levitron, without any digital nonsense. No sooner said than done. I spread the flour of creativity for all to see.1. Brief description
Levitron is a device that keeps an object in balance with the forces of gravity with the help of 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.It turned out this:
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.
In the presence of a permanent magnet near the lower sensor, the control unit will generate a signal proportional to the field of the magnet, amplify it to right level and transmit to PWM to control the current through the coil. Thus, there is Feedback and the coil will generate such a magnetic field that will keep the magnet in balance with the forces of gravity.
Something abstruse everything turned out, 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 gives the minimum signal - the coil works at full power;
- They brought the magnet close - the induction is very different - the signals from the sensors are very different - the control unit gives out the maximum signal - the coil turns off completely - no one holds the magnet and it starts to fall;
- Beckons 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;
- Beckons is attracted - 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;
- 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, it arises dynamic balance- the magnet just hangs in the air.
3.Design
The main element of the design is an electro-magnetic 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 on a D36x48 plastic frame, about 600 turns. According to calculations, with a resistance of 4.8 ohms and a power supply of 12V, the current will be 2.5A, the power will be 30W. This is necessary for the selection outdoor unit nutrition. (In fact, it turned out to be 6.0 Ohm, they hardly cut more wire, rather saved on the diameter.)
Inside the coil is inserted a steel core from door hinge diameter 20mm. Sensors are fixed at its ends with hot glue, which must be oriented in the same direction.
The coil with sensors is mounted on an aluminum strip bracket, which, in turn, is attached to the housing, inside which is the 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 current up to 3.2A at 12V.
An N35H magnet D15x5 with a glued Coca-Cola can is used as a levitating object. I must say right away that a full jar is not good, so we make holes at the ends with a thin drill, drain a valuable drink (you can drink if you are not afraid of chips) and glue a magnet to the top ring.
4.Schematic diagram
The signals from the sensors U1 and U2 are fed to the operational amplifier OP1 / 4, connected according to the differential circuit. The upper sensor U1 is connected to the inverting input, the lower U2 is connected to the non-inverting one, that is, the signals are subtracted, and at the output OP1 / 4 we get 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 scheme and allows you to achieve the effect of complete stability, the magnet will hang in its tracks. How it works? The DC component of the signal passes through the divider R6R7 and is attenuated by 11 times. The variable component passes through the C1R7 filter without attenuation. Where does the variable component come from? The constant part depends on the position of the magnet near the lower sensor, the variable part arises due to the oscillations of the magnet around the equilibrium point, i.e. from a change in position in time, i.e. from speed. We are interested in the fact that the magnet is 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 responsible for the stability of this position.
Further, the prepared signal is amplified by OP1/3. With the help of a variable resistor P2, the necessary gain is set during the tuning phase 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. Very handy thing, do not remove the power supply from the outlet if the magnet is removed. The trigger level is set by the variable resistor P1.
Next, the control signal is applied to the pulse-width modulator U3. The output voltage range is 12V, the frequency of the output pulses is set by the values of C2, R10 and P3, and the duty cycle depends on the level of the input signal at the DTC input.
The PWM controls the switching of the power transistor T1, which in turn controls the current through the coil.
The LED1 LED can not be installed, but the SD1 diode is necessary to drain excess current and avoid overvoltage at the moments when the coil is turned off due to the phenomenon of self-induction.
NL1 is our homemade coil, to which a separate section is devoted.
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 apply graphs of the transfer characteristic, frequency response and phase response, and oscillograms at the output of the PWM and coil.
5. Choice of components
The device is assembled from inexpensive and affordable components. The most expensive was copper wire WIK06N, for 78 meters WIK06N paid 1200 rubles, everything else, taken together, was much cheaper. There is generally a wide field for experiments, you can do without a core, you can take a thinner wire. The main thing to remember is 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.As magnetic field sensors U1 and U2, SS496A analog Hall sensors with a linear characteristic up to 840 gauss are used, this is the very thing for our case. When using analogs with a different sensitivity, you will need to adjust the gain by OP1 / 3, as well as check for the level of maximum induction at the ends of your coil (in our case, with a core, it reaches 500 gauss), so that the sensors do not saturate at peak load.
OP1 is LM324N quad op amp. When the coil is off, it gives out 20mV 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 the closest in actual value for installation as R1, R2, R3, R4.
Ratings C1, R6 and R7 are chosen by trial and error as the most best option to stabilize magnets of different calibers (tested N35H magnets D27x8, D15x5 and D12x3). The R6 / R7 ratio can be left as is, and the value of C1 can be increased to 2-5 microfarads, in case of problems.
When using very small magnets, you may not get enough gain, in which case cut the value of R8 to 500 ohms.
D1 and D2 are ordinary 1N4001 rectifier diodes, any will do here.
The common TL494CN chip is used as a pulse-width modulator U3. The operating frequency is set by the elements C2, R10 and P3 (according to the 20 kHz scheme). The optimal range is 20-30 kHz, at a lower frequency 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 from the same series will do. When choosing other transistors, it may be necessary to install a radiator, be guided by the minimum values of the channel resistance and gate charge.
SD1 is a VS-25CTQ045 Schottky diode, 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, the taste and color, you can put more of them so that everything glows with multi-colored lights.
U4 is a 5V voltage regulator L78L05ACZ to power the sensors and the op amp. 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 intended. The device works stably around the clock, consumes only 6W. Neither the diode, nor the coil, nor the transistor are heated. I am attaching a couple more photos and the final video:
7. Disclaimer
I am not an electronics engineer or a writer, I just decided to share my experience. Maybe something will seem too obvious to you, and something too complicated, but I forgot to mention something at all. Feel free to make constructive suggestions both for the text and for improving the diagram so that people can easily repeat this if they so desire.The principle of operation of the Levitron toy, which clearly demonstrates the state of weightlessness, is based on the action of a magnetic field that holds objects of small size in the air.
Such toys, unfortunately, are not yet produced by the domestic industry, so the demand for them cannot be satisfied. Of course, it is possible to order Levitron from abroad, but the cost of the toy (already quite high - $35) increases significantly due to the shipping cost.
But on the other hand, nothing can prevent you from making a Levitron with your own hands in one of two known ways: on an electromagnet or on permanent magnets.
The second of these methods is much simpler than the first, besides, specific knowledge in the field of physics is not required, and this device also does not need electrical power.
Materials for the manufacture of Levitron
So, we need three ring-shaped magnets with sufficient power to make a toy. 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, made from an alloy of neodymium, boron, and iron. High temperature will negatively affect it, so this magnet should be kept away from heat. So, a cell phone magnet can be of two types - in the form of a round plate or in the form of a ring. The ring magnet is put 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 light material, such as a composite or plastic.
Levitron setting
The setting should be approached with particular scrupulousness, because this part of the work is crucial and is the most time-consuming. Ring magnets must be connected to each other by 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 in 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 start the top, you will need a few 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 spinning top is spinning normally, we begin to gently raise the platform until it flies up.
If our spinning top flies up with excessive swiftness, its weight should be increased. If it deviates in one direction, then you can correct the situation by placing paper sheets under the opposite one. These actions allow you to adjust the base of our toy so that it is clearly at sea level.
