>> A more modern name for a synchronous motor is a permanent magnet stepper >> motor. Any PM stepper, and a couple of microfarad capacitor becomes a >> synchronous motor when connected to the power line.
I've seen a data sheet for a motor that's actually spec'd for both uses. I don't know how common that is. >The old pre-digital way of generating a rotating field for a synchronous >motor was a shaded pole. They worked well for low torque applications like >clock motors. I saw plenty of them when I was a kid. The rotor was hidden >in a package with the first layer of gears. I assume it was a permanent >magnet but never took a package apart to verify that. You're thinking of the Telechron clocks (also branded GE, Revere, and Herschede). Some good pics of the motors here: http://telechronclock.com/ https://clockhistory.com/telechron/ Also, lots of pics of the clocks themselves: http://www.telechron.net/main.htm There are people who rebuild the rotors, for a fee (usually they'll swap yours for a rebuilt one). I've fixed one clock this way, and I have a couple of others that need it. The other major manufacturer was Sessions, they had a bayonet system that allowed you to replace the whole motor easily (not including the gears), but they weren't as durable as the Telechrons. A friend of mine has an early Sessions clock where the motor is held in with #5 screws. I'd never seen these before, it took me a while to find the right wrench to take it apart. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
