A great way to figure out how things work is to take them apart. In the Hackers group, we unscrewed, hammered, de-soldered and detached the parts from the insides of an old living-room DVD player, a computer CD player, and a speaker from a stereo, to see what we could find.
Group members de-soldered components such as switches and capacitors that we will use in new projects, extracted and examined motors from the CD/DVD players, and got a working speaker from its housing. They powered up the motors with DC batteries to see how they work, and hooked up the speaker to a phone headphone jack (whch worked but would need amplification).
CDs and DVDs are great because they include different high-quality motors for spinning the disc, moving the laser read head forward/backward, and ejecting the tray.