I bought an old rotary phone with the hopes of cannibalizing it for a doorbell/intercom thing in my apartment building. It looks absolutely marvelous inside:
However, I'm having trouble figuring out how the ringer circuit works without taking it completely apart, since the wires are all bundled together so neatly. But I've been holding off from doing that - the existing system already supplies an AC signal when the doorbell downstairs is pressed, so I think I don't need to do too much to hook that into the ringer.
Can anyone tell me about how these old ringers generally worked? I think if I had a basic idea for how they were constructed, I would be able to achieve what I want without risking breaking it.