They are found in electric motors and loudspeakers. Electric bells like the ones used in most schools also contain an electromagnet. The slideshow describes how an electric bell works.

It’s an electromagnet pendulum analog circuit ... took the time to highlight each part of the schematic in order to work through a complete explanation. In the end, this analog circuit should ...

Maybe [Josh] had seen a couple more than we have when it occurred to him to take one apart to see how they work. They are designed to run indoors from unreliable light sources and seem to bob ...