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Re: classic demo, and motor modification
In a message dated 99-05-12 05:50:36 EDT, you write:
<<
> Is there any easy way of telling if motor is spinning in synch to the AC
> signal? Would viewing it under incadescent or flourescent lights do the
> trick? I've machined, more or less acurrately, four flats into the rotor
> of a split-phase induction motor, one of 1725 rpm. Will the odd speed
> effect the synching effect? The thingg still runs, but I'd like to know
> if I've succeeded, so I'll use the motor in place of a universal one for
> a rotary SG I'm making.
Grayson,
Either a 1725 or 1750 rpm motor will give you 1800 rpm after the
motor is modified. I tape a white cardboard disc to the motor shaft,
and draw a heavy thick black line across the diameter of the disc,
and view it under fluorescent light. Incandescent light won't work.
Some folks have trouble seeing
the locked condition though. It helps to use a variac to bring up the
speed. You can see (and hear) it hunting, and trying to lock at
lower voltages. When it locks, the sound gets very steady, and
you'll see the line appear at right angles. The motors often lock
at about 35 to 40 volts for a 120 volt motor.
John Freau
> thanks,
>With silent lightning in my hands,
> -The Electrophile-
> Grayson Dietrich >>