For my EE 3 class my friend and I wanted our final project to have something to do with magnetic levitation since we both found that field to be very interesting. Our intial idea was to build a model Maglev train and track. However, after consulting our professor we decided that our idea was too ambitious to accomplish in a few weeks. So we decided to build a static magnetic levitator with an optical control system.
Our setup used an electromagnet through which we could pass varying amounts of current to generate magnetic fields of different strengths. We used an optical control system to provide feedback. This system consisted of an infrared LED and two phototransistors (one as reference and one as a sensor). When an object was placed in the magnetic field of the electromagnet, it would block the infrared light incident on the phototransistor which would change the current flowing through the electromagnet to balance the weight of the object.