Universal motor

Would someone remember how to use a bridge rectifier to reverse a
universal motor. Roger Aultman
Reply to
Roger Aultman
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You don't need a rectifier. Just feed the field in series with the other brush.
Rob
Reply to
trainfan1
You might have to first check that the field coils are capable of taking the same current as the armature coils.
Then you might have some control problems since I think I remember that the theoretical top speed of a series would motor is infinite, and the practical limit on the top speed is when the armature disintegrates :-)
Jim.
Reply to
Jim Guthrie
Roger,
Feed the field coils only through a bridge rectifier so that they are always at the same polarity no matter the polarity of the applied voltage.
Jim.
Reply to
Jim Guthrie
This occurs when a series motor is run without load and is easily tested with small motors.
Prototype conventionel traction motors are series motors but a no-load situation cannot happen in normal operation.
Reply to
Erik Olsen
A friend found a link to a digitraxx site having a diagram, it is as you describe, the field goes to the + and - leads of the bridge rectifier, the brushes are in series with the AC leads. This is on a Scale Craft 00 motor, spins like a top of a H-0 powerpack. Roger
Jim Guthrie wrote:
Reply to
Roger Aultman
Dear Roger:
Old Lionel motors are series wound. They do not run away or throw their windings when lifted off the track, because the top speed is limited by the friction of the bearings and in the gear drive. Series winding gives you higher starting torque than shunt winding. (where the field and brushes are in parallel) and with these small motors you need all you can get.
The motor brushes are in series with the bridge rectifier's AC terminals. Run a wire from one supply terminal (or pickup) to one brush. Run another from the other brush to one rectifier AC terminal. Run another from the other AC terminal to the other supply terminal (or the other pickup). Connect the field across the bridge rectifier's + and - terminals. You will now have to run the motor on DC current, because on AC it will attempt to reverse direction 60 times a second and be nothing more than a buzzer.
When I say 'pickup' I mean your wheels, shoes, overhead trolleys, etc., unless you are using DCC, in which case I mean the decoder output. With DCC, of course, you have AC in your rails, but your motor is still being fed pulsed DC.
This has all been said before in this thread, but I wanted to collect it all in one place for convenience. :)
Cordially yours, Gerard P.
Reply to
pawlowsk002
Hello Gerald A friend found a link to a page that had a diagram to wire the Bridge rectifier as you describe. It works well the not real small 00 motor runs quite nicely, but draws over one amp, this may be typical. The next challenge will be to get the chassis tuned up, there are some driver and valve gear issues. Roger Aultman
snipped-for-privacy@gann> Dear Roger:
Reply to
Roger Aultman

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