I'm trying to build a telegraph key and sounder. The sounder that I have designed (well, saw online) is a metal nail (which is ferromagnetic) with at least several dozen (maybe 200+) turns of wire around it. When a current is on the wire, the nail should become an electromagnet, and then pull down some kind of ferromagnetic metal strip, creating a sound. Upon being released, the strip bounces back up (maybe using a rubber band) to clang against something else. My issue: Using either two AA batteries or two D batteries, I can't get the nail to attract much of anything, not even close to making a sound. I haven't found a good metal strip yet, but even paper clips barely get attracted to the nail. If a compass is close enough, it will detect the magnetic field. Any suggestions? Is it possible that the nail isn't very ferromagnetic, or is there something better to use? Thanks for any help.