Watch the World Turn with This Levitating Globe

Levitating an object with a permanent magnet is normally not possible, as demonstrated by Earnshaw’s theorem from waaaaaay back in 1842. Today, however, you’ve probably seen all kinds of toys where magnets do indeed levitate an object in mid-air, and this project shows how such a “physics-defying” device can be constructed.

The trick here, and presumably in other levitating units, is that an object isn’t levitated by a permanent magnet at all, but instead by an electromagnet that can be cycled on and off for PWM control. As demonstrated in the video below, one can place a stack of permanent magnets under the build's electromagnetic coil — by itself, or even weighted down with a small screwdriver or globe — and it will stay a short distance away.

inside that coil is a SS49E Hall effect sensor, which switches the electromagnet off when above a certain threshold and on when it’s below this point. Both the electromagnet and permanent magnet contribute to this reading, so it stays activated until another magnet causes it to exceed the threshold. It then turns off when it gets too close, and rapidly on again when just out of range. No microcontroller is used in this simple design. Rather, an LM358 op-amp is tasked with control, along with a trimmer pot can be used to set the threshold, effectively setting the distance between the coil and permanent magnet.