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The Flyingmagnet©

to Active stabilization & compass

What's that ?

An object named "Flyingmagnet", useless, seemingly... its most obvious duty being to take up its duty! This realization requires meticulousness and makes possible to apprehend unusual electric, magnetic and mechanical behaviours, which for some time should please any hobbyist familiar with electronics and metalwork, even model makers, moreover this object comprises an aesthetic dimension which can be developed according to the inspiration of each one.

Presentation of theFlyingmagnet©

An aluminium or brass base comprising the passive devices for the magnetic levitation (permanent magnets) and active devices for the stabilization consisting of a printed circuit wired as an analogical servo controller and linked to adequate sensor as input and magnetic coils field as output. A flat drilled aluminum foil covering up this assembly.
The magnetic object floating over this base: in this geometry identified as #1, 6 are tested, that consists of 2 sets of permanent magnets inside a brass tube of sizes :15 mm diameter by 150 mm length.
The whole is powered from a wall plug-in transformer (secondary 15 Vca).

Original design
Positionning using optical sensor. (reflection & lateral reading).
Embase test jig,
Positionning using hall sensors. (lateral reading).
 Original first flyingmagnet  Redesigned flyingmagnet
More complicated for the FLYINGMAGNET© concept More performing for the FLYINGMAGNET© concept

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Before going further ...

Natural stabilisation of magnetic suspension by Archimedes's principle

Test jig in geometry #0
Obviously, the criteria defined in the following page are not respected.
The sphère (full of water): D=68 mm, V=165 cm³
emerged weigth: approximately 170 g
apparent maximum weight in the chosed working range:
approximately 70 g
  spheric volume and Archimède  Magnetic suspension stabilized by Archimede's law
The sphere: full of water (weight zero when fully immerged) is located under the object in suspension.
The curve of variation of weight of the sphere in function of the height of emerged part, takes advantage on the curve of the attraction force in function of the distance between the magnets.
Overview of the behavior of this setup: video 300 ko (.AVI)
Vice versa: an empty sphere, equipped with a magnet (geo #5, page "tech") can be anchored stably above a magnetic mass without material link. This is perhaps not a good idea to try that in an aquarium, the fishs may lose the North.
The neodymium magnets:
sphere: 25,4 mm (1"), disc: 25,4 mm x 6,35 mm (1" x 1/4"). The adjustment at the middle of the operating range is done by sliding the main tube and the support of the magnet.
Distance between magnets: approximately 55 mm (2")

The stable position shown, allows a vertical swing of a magnitude more than 2 cm (3/4") without losing control (falling of the magnet or stick to the ceiling), the damping is perfect!
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Active magnetic suspension stabilization by servo-controller

Two are better than one !
Sphere neodymium, diam: 19 mm (3/4") and a fragment of neodymium epoxy coated, spaced by approximately 50 mm (2").
The two spheres are suspended and linked magnetically. Moving one moves the other, removing one makes the other fall. The spherical form is absolutely not obligatory.
 Magnetic levitation of 2 neodymium magnets, superimposed & linked by there magnetic fields  Magnetic levitation of 2 neodymium spheres of 12,5mm, superimposed & linked by there magnetic fields

"The holidays compass"

Determining the poles of a magnet :
The pole of a rotating free magnet that orients towards the geographical North pole, is defined as the North pole of this magnet, and consequently the North pole is the one that will attract the south tip of a compass's needle.

Note : This test must be carried out at a good distance from the magnet in order to avoid the reversal of the compass's poles!

How the compass is made:
Hollow Sphere in soft iron (fancy chocolate box...), suspended magnetically and two spherical magnets of 12.5 mm, poles in series at 180 °, positioned on the equator.

The Stability control uses 2 field coils (Top & bottom), one disc magnet 25x5mm inside the sphere at the top, one disc magnet 10x5mm at bottom outside of the sphere and two disc 100x5mm magnets stacked at the top of the core of the main coil (all magnets "neodyme").
The controller is the same as the one used in the other demos.

Compass oscillating around the north after being disturbed :
Video 270 Ko AVI - (wmv9) : click on picture

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Some links to websites in English or in French.

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Last update: 19 February 2020

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