Hi, My first post here....I have some physics background, but it was a while ago. I remember seeing an excellent demo on electromagnetics, using a magnet, coil, CD player, and the top of a cardboard box to make a speaker. I'd love to find a step-by-step so I can show this to a class of high schoolers. Any good ideas on where I should look? I'd prefer not to trash the CD player if possible, and I need to figure out what kind of magnet to use, etc. Thanks in advance for any help!