BUILD A CASTLE IN THE CLOUDS

摘要

The magnetic field of a simple magnet will not allow a stable suspension of a magnet in space repelled from below. This is explained by Earnshaw's theorem, which says that stable stationary equilibrium cannot be obtained with just the magnets. We need some electronic control of the situation to stabilize magnetic levitation. This is accomplished by using electromagnet coils, and Hall-effect magnetic sensors to sense the field and trigger minute corrections to the field to maintain balance. I really wanted to make my own circuit and use a microcontroller to adjust the field. I used a circle of stacks of Neodymium (Nd) magnets. I was not successful in doing this. The microcontroller (a PIC at 50 MHz) was not fast enough to achieve the balance. I believed an analog circuit is what would be required; this is not within my abilities. So, I gave up on this part and bought a magnetic levitation unit (Figure 1). The wireless transfer of power was something I could do, but it took quite a bit of experimentation to achieve this. Charging coils and circuits are available to charge phones and other things wirelessly, but they rely on very close contact between the transmitting and receiving coils. I tried one of these, and as soon as the coils are separated by even a small amount, the current drops to almost nothing. I wanted the current to travel an inch, and found out this was not as easy to accomplish.