A hamfest dealer had some really small cellphone/pager vibrator motors for $.25 each. Curious to see how they were constructed, I disassembled one and cut the casing open. Here's a photo for all who have wondered what's in them.
formatting link
The armature, (not fully seated on the magnet) is a hollow tube of laminated copper wire. no iron in it.=20 I ran one up to 15V input with the weight still on the shaft, which kep the speed down. It didn't burn out, but after about 30 seconds gradually ramping the voltage up, it was beginning to smell a bit. (The magic smoke didn't escape :-)
-- Email reply: please remove one letter from each side of "@" Spammers are Scammers. Exterminate them.