The Forgotten Toy of the ‘90s

The Levitron was a toy from the 90s. Here I have a different brand. It's a great demonstration of spin-stabilized magnetic levitation. So what does that look like? First we spin the magnetic top on this tray and then lower it down to the magnetic base. And it floats. There's no trick here, it's just floating using magnets. MIT has a page explaining the Levitron and it has this diagram. I think mine might be a bit different as I'm not sure if it uses a ring magnet or not, but the idea is it looks something like this. And there's a sweet spot where the magnet is pushed both to the center and up, so it should stay there. The problem is it has a tendency to flip over, so this would be unstable equilibrium. Stable equilibrium can be shown by a pendulum hanging down. If it's pushed in one direction, it eventually settles back to where it was. If it's facing up, it would be unstable equilibrium. If it were perfectly centered, it would stay there, but any disturbance will cause it to fall. So our top needs something to keep it stable. There are products on Amazon that use computers and electromagnets to balance, and I also made a PID-controlled inverted pendulum. It moves the cart to keep it facing up. But the Levitron doesn't have electronics, so how can we make it work? The answer is gyroscopic precession from spinning. If this spinner is spun clockwise from the top, the arm closest to us is moving to the left. If I try to apply a torque and push it down, the two vectors will actually combine to make it go diagonally, making the spinner face this way. It has a tendency to fight you on which way it wants to go. The same thing is happening with a top. Gravity wants to pull it down, but it's pushed in a different direction because of its spinning, causing a spiral. This stability prevents it from flipping over. I'm surprised these aren't more popular, and I think part of the reason is that they're difficult to set up. The bed has to be leveled, and you have to adjust the weight of the top itself. The brand I went with was the Smithsonian Magna Gyroscope. I had to add additional magnets to mine. I don't know if I had a bad unit. I bought mine used. So I can't speak for the whole brand, but there's mixed reviews, and Amazon has pretty good return policy. If you liked this video, you can click like, and if you want to see more from me, you can subscribe. I'm still trying to figure out where I want to go with this channel, so feedback is appreciated, and thanks for watching.