Levitron

# Levitron

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Encyclopedia
Levitron is a brand of levitating toys and gifts in science and educational markets marketed by Creative Gifts Inc. and Fascination Toys & Gifts. The Levitron top
Top
A top is a toy that can be spun on an axis, balancing on a point. This motion is produced in the most simple forms of top by twirling the stem using the fingers. More sophisticated tops are spun by by holding the axis firmly while pulling a string or twisting a stick or pushing an auger as shown...

device is a commercial toy that displays the phenomenon known as spin stabilized magnetic levitation
Spin stabilized magnetic levitation
Spin-stabilized magnetic levitation is a phenomenon of magnetic levitation where a magnet is levitated via magnetic forces above another magnet or array of magnets, and stabilised by gyroscopic effect due to a spin that is neither too fast, nor too slow....

. This method, with moving permanent magnets, is quite distinct from other versions which use changing electromagnetic fields, levitating various items such as a rotating world globe, model space shuttle or VW Beetle, and picture frame. 750,000 units were sold from 1994 through 1999.

## The device

The toy is essentially a permanent magnetic top and base plate, ring or alternate geometric configuration. Functional parameters, such as the top rotation
Rotation
A rotation is a circular movement of an object around a center of rotation. A three-dimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation...

rate or top weighting, are stringent. Employing principles of the magnetic field and gyroscopic stabilization, the Levitron induces levitation in its top through a series of interactive steps. The levitated top's stabilizing rotation undergoes natural, gradual slowing, so that the levitation phenomenon fails within four minutes unless external power is supplied to sustain rotation.

To levitate the top, a plastic plate is placed on top of the magnetic base, and the top is spun on the plate at between 25-50 rotations per second (1500-3000 rpm). If too slow, the top falls over and slides off sideways; if too fast it does not orient itself to follow magnetic flux as it moves, and slides off. Since it can be difficult to spin the top fast enough by hand, Creative Gifts makes a battery-powered, hand held device to spin the top with an electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

. Next, the plate is lifted by hand until, if conditions are right, the top rises above it to an equilibrium
Mechanical equilibrium
A standard definition of static equilibrium is:This is a strict definition, and often the term "static equilibrium" is used in a more relaxed manner interchangeably with "mechanical equilibrium", as defined next....

point. The top must also be weighted with washers of various sizes supplied in the kit. If too heavy it will not rise above the plate; if too light it flies off.

After a few minutes, the top falls when air friction slows it below the critical speed. Air temperature, air currents, ground vibration, and power source interruptions also alter the delicate equilibrium necessary to keep the top stable. More expensive laboratory versions can sustain a levitating top indefinitely by sustaining the top rotation actively compensating for aberrations in rotation. The makers of the Levitron have developed a "Perpetuator", which sits under the Levitron and sends out an additional magnetic pulse. The additional force nudges the spinning top enough to maintain a constant speed. With a constant speed, and with the Levitron perfectly level, the Levitron top can spin for longer periods of time.

### Invention and patents

The device that was later named Levitron was originally invented (c 1976) and patented (1983) by Vermont inventor Roy Harrigan. A Seattle entrepreneur, Bill Hones, came across the patent in the process of trying to develop a levitating magnet. Hones borrowed the prototype from Harrigan, analyzed its physics with help of his father, who worked at Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

, then filed an "improvement patent" of his own.