Applications of magnetic levitation

[Pranav Jha]

i am a high school student and have designed a magnetic levitation system for my school science fair.
The circuit used is: http://uzzors2k.4hv.org/projectfiles/magneticlevitator/Magnetic Levitator circuit.GIF
However, i would like to scale up the project and find some REAL WORLD applications for the system. I have been thinking about this for two days now but haven't come up with anything yet.
One idea would be an earthquake detector (need to think about that)
Has anyone got anything else in mind?
(P.S.: As soon as possible)

 

[JaredJames]

You'd need two electro magnets to get this to levitate.

The way you've set it up now (from that colour image) it would simply attract to the metal rail at the bottom and stick to it.

 

[Pranav Jha]

You'd need two electro magnets to get this to levitate.

The way you've set it up now (from that colour image) it would simply attract to the metal rail at the bottom and stick to it.

This circuit works by comparing the signals from the sensors with the first op-amp and sending out a voltage proportional to the difference or "error". The error signal is then sent through a compensation network which acts a high-pass filter, allowing quick changes in error to pass easier than slow changes. This is required to stabilize the control loop, and without it objects would just flutter close to the electromagnet due to the system being unstable. The signal is then amplified to it's original amplitude, since the compensation network attenuated it, and finally drives the TIP122 Darlington transistor, which controls the electromagnet current. The extra diodes around the transistor are to prevent damage to the transistor. The signal diode on the base prevents reverse biasing the base, which is damaging, while the two 1N4001's give a path for the magnetizing current to flow when the electromagnet turns off. The optical components used aren't too critical, as long as their wavelengths match up ok, and the detection/emission angles aren't too narrow. The IR LEDs are TIL38, which are 940nm peak, have 15 degree spread, 35mW and 100mA max. The detectors are PT204-6B, which are IR phototransistors.

 

[JaredJames]

Ah, I was thinking that but I'm not the best at electronics so didn't want to comment on the wrong thing (which I ended up doing anyway).