Re: Electricity Merit Badge Problems
Len Christiansen (lrchristiansen@WORLDNET.ATT.NET)
Tue, 4 Aug 1998 14:53:52 -0500
Michael Kauffmann wrote:
> An electrical engineer serving as a counselor for electricity
> merit badge says the motor diagramed in the merit badge book
> does not work. He's taken this to two other engineers at the
> utility he works for but no one can figure out the problem.
> Has anyone else run into this problem?
I don't have the Electricity MB pamphlet any longer, but my son built
the motor out of the MB pamphlet several years back. It did not run at
first. As I recall the problem was with the commutator. With just one
wire the commutator is not in contact with the brushes for enough of an
arc to throw the motor over. It seems that we lengthened the commutator
wire on each pole so that it could make three passes up and down the
shaft, which was insulated from the commutator wires with electrical
tape. By playing with the positioning and the gap between these three
passes we were able to keep the contact with the "brush" long enough to
get the motor to start on its own. You also have make sure contact with
the commutator for one pole breaks before contact is made with the next.
He even modified the design to make a four pole motor because he wanted
to see if a four pole motor would run faster for a science project. He
used tin can lids cut into an X-shape for the core so that all four
poles would be in the same plane.
Len Christiansen email@example.com
SA Troop 292, Mobile, AL ...I used to be an eagle (SR-101)!
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