Most AC motors (the ones without brushes) will brake if you feed 'em some DC. Steppers (but they cog), shaded-pole, or hysteresis types, all have a rotor without driven windings, and DC on the stator makes them into brakes.
This gets you back to something that brakes proportionally to speed, though.
I thoughty they only braked while spinning and once stopped there is no braking force. I ordered some MR fluid and will try making my own magnetorheological brake. Eric
That is true for AC motors. For steppers, since they have a permanent magnet rotor, the braking continues, but things are a bit rough until it gets to a stop. Perhaps sense the speed, and when it comes close enough to a stop, switch from AC motor to stepper. (Make things biggern than you want. :-)
Have fun with that -- and let us know how it goes.
Good Luck, DoN.
I'm looking forward to finding out myself. I looked online for small quantities but couldn't find any. Looked on ebay with no luck and then a couple days later some showed up. It sounds like the perfect stuff for my needs. Eric
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