gene heskett wrote: > > Well, I did the deed, and I have verified that when the switch is off, > there is a dead short across the receptacle the motor is plugged into. > About 20 tests with the saw motor plugged into it, no effect. Unplug the > saw motor and plug in a cheap Skil router I have installed in the right > table. Also no effect. Both coast to a stop as usual, taking about 15 > seconds for the saw, and at least 10 for the router to come to a complete > halt. > > Two universal motors in a row with absolutely zero residual magnetism??? > > Is the grain oriented silicon steel that most of these field stacks are > made of for the last 25 years that free of hysteresis? > > Boggles this old electronics types mind... > Well, that lawnmower motor may have had some special feature, either in the steel, the shape of the field poles, or something that made this work. Maybe they even had a little permanent magnet buried under the field windings. Very interesting that this doesn't work at all on those motors. Now, on the router, it needs to be one with no speed control built into it, I can easily see an SCR speed controller preventing the shorted power source from making this work. Also, a number of routers even without speed controllers have a bridge rectifier in them, so they run the motor on intermittent DC.
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