Introduction: Magnetic Levitating Globe Tear-apart and Fix

About: I am an American teaching English at Shangluo University, Shaanxi. I like making machines that do interesting but fairly useless things - I call them Quixotic Machines.

First off, I am not an electronic engineer - barely know the difference between a potentiometer and a variable capacitor. My levitating globe only worked sporadically and finally it quit working at all so I had nothing to lose and chose to tear it apart because I just wanted to see what was inside and how it worked. My fix was simple: I snipped off the two potentiometers inside and it started levitating again. Why, don't know. Maybe they were just way out of wack but I did try adjusting them for a long time before I decided to cut them out. I also tested them with a multi-meter after I took them out and they were both working. Although when I first took the base apart, one of the pins on one of the potentiometers was broken and I had to resolder it to the board but that did not fix my levitator. I think that the occasional bashing the base gets when you let the magnet impact the base may eventually break some solder connections and perhaps this caused the initial problem. Don't know.

Please note: I do not suggest this as a fix for your broken levitator. It just happens to fix mine but I still have difficulty getting it to work all the time. But before I cut out the pots, it would not work at all so I guess this counts as a fix of sorts. When I try to float the magnet above the base, I can feel the magnetic x and y fields. If where they intersect is too far away from the center of the permanent magnet then I will not be successful in floating the magnet and just have to turn off the levitator until the coils cool off and try later. I suppose the purpose of the potentiometers is to keep the magnetic field centered on the center of the permanent magnet and center of the coils. Without the pots, the center seems to float around a bit and I just have to catch it near the center to float the magnet.

Cutting apart the globe: First I cut the globe apart with a hacksaw. You can't get this particular one apart any other way. The manufacturer obviously does not want you to take it apart but I took mine apart the first day because I needed the magnet to float other things besides the globe. After cutting it in half you can pry the induction coil lights off the top of the magnet and then pry the magnet lose from the globe. Use a screwdriver to gently pry around the magnet until the brittle glue finally breaks.

Inside the base: The photos are added here in case you want to see closeups of the the ICs and transistors. Not much else to do or see inside this levitator. No other adjustments than the two potentiometers.

There are two transistors for each coil, a voltage regulator, two op-amp ics and a CD4066 4 way switch IC. So there is no computer chip running any code or PID routine.

How the levitator works: the large permanent magnet in the base is the same pole as the globe's magnet and therefore pushes against it as the globe magnet approaches the base. But the 4 electromagnetic coils attract the globe's magnet. There are are a couple (actually three I think) hall effect sensors in the middle of the coils which control the position of the floating magnet. The two 100k potentiometers control either the coils or the hall effect sensors, not sure which, to keep it centered.

Step 1: Photos of Inside the Flying-saucer Magnetic Globe Levitating Base

On the top of the circuit board:

large round permanent magnet (nice one)

wireless inductor for powering lights in globe

4 coils

2 (perhaps 3) hall effect sensors

2 adjustable 100k potentiometers (28 turn)

On the bottom of the circuit board:

4 B772m transistors

4 B882m transistors

1 78mo5 voltage regulator

2 LM324 op amps ics

1 cd 4066 quad switch ic

Step 2: