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Already set a bookmark? |Floating sphere| |
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Preface |
| Anti-gravity is the idea of creating a place
or object that is free from the force of gravity. It does not refer to
the lack of weight under gravity experienced in free fall or orbit, nor
to balancing the force of gravity with some other force, such as electromagnetism. Magnetism is fascinating, especially when it is used to cause objects to levitate or float or be suspended in the air, defying the gravity which keeps us on the ground. How can this be done? Well, look my self made magnetic levitator :-) |
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The floating sphere |
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| Here I present a suspension device in which a neodym magnetic sphere levitates. The electronics are in the pedestal and on top is an electromagnet with sensor (SS495A). The voltage supply comes from an external power supply unit with 15V direct current. | ||
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The machanical structure |
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| Left Picture: The coil (electromagnet)
is the heart of the Levitron (see
magnetic flow density in coils). Right Picture: Here you can see the aluminium base plate with a 99 mm diameter and the two brass bearers. |
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| View from below: Here is room for the electronics on the breadboard plate. The cables for supplying the cupola go through the boreholes (sensor & coil). | ||||
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| The dome: From aluminum milled. View inside the socket: The Hall sensor is fastened in the tip of the socket with a rubber disc. | ||||
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| A view on the inside: The electromagnet with magnetic field sensor and neodym ring magnet in the aluminium socket (left). On the right the circuit board. | ||||
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| Left photo: The circuit board was fastened from
below with four M3 screws. Right photo: Grooves in the brass bearers (6 mm deep, 2 mm wide) to hide the cables that run upwards. |
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The circuit diagram and schematic construction |
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Here the circuit diagram of the levitron.
On the left side you will see a 5Volt-Regulator 78L05 (
see data sheet) this is the power supply for the hall sensor SS495
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see data sheet) it is also used as referece voltage for the op-amp.
With the adjustable resistor (R2) you can change the distance between
flying object and coil. The op-amp UA741 or LM348 (
see data sheet) is to see as differential amplifier.The coil (L1) is attached to the high-power driver P-channel MOSFET IRF4905 ( see
data sheet) to amplifying the output signal from op-amp. We should
protect the MOSFET from the coil's kickback voltage. When its magnetic
field collapses as the output MOSFET turns off, a high voltage spike is
generated. This can easily overcome a MOSFET's maximum breakdown voltage.
So we provide a protection diode (D1) across each coil, which passes current
to keep its forward voltage drop down to about 0.7v.I use a bench style adjustable regulated and metered dc power supply. The maximum switched current was 500mA. With levitating magnet need this circuit 60mA only and without magnet the current increases to maximum. That is too much for this coil and she warm up. So you can´t use it for permanent operation. For a safe operated you will need a current limiting. |
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Photos |
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| The cupola with the coil and the sensor is only
lodged between the brass bearers. An o-ring (black) provides additional
stability. The Hall sensor SS495 is situated in the small "bump"
below. The cupola is closed with an aluminium lid. Also playmobil character Bernd has fun with the Levitron. |
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| Wow. | ||||
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| In the garden, already very decoratively! | ||||
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| Slightly larger! | ||||
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| Fascination floating: I can't get enough of this! | ||||
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Circuit diagram |
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Video |
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Already a set bookmark? |Floating sphere| |
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Other constructions |
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