Re: [CAD_CAM_EDM_DRO] unknown motor

Weyland wrote:

> From: "Jon Elson" <elson@...>
> >
> > Yeah, I was looking at one of those just this afternoon. Somehow, I
> > suspected it wasn't REALLY a DC motor, but a 'brushless DC' motor.
> > Now, I think you've confirmed it!
>
> Heilsa Jon~!
>
> Pardon my ignorance, but what would this mean?
> As in, what's brushless as opposed to brushed?
> Can you give me an example of an application I could relate this to?

Brush motors use a commutator and brushes to turn around the
current in the windings of the armature after they have passed a pole.
These motors may have fixed permanent magnetic poles, but
the armature windings rotate.

Brushless motors use an electronic circuit to turn the current around.
Some have sensors, usually Hall effect, that sense the position
of the magnets. In these motors, the windings are fixed, and permanent
magnets in the rotor spin. The advantage is theres no electrical
connection needed to the moving parts, greatly increasing reliability.

Some brushless motors, like in computer fans, have the electronics
inside the motor. Many brushless motors in other application for
positioning, driving laser printers and copiers, etc. have the electronics
separate, on the device control circuit boards, instead of the motor.
These motors have at least 3 wires, sometimes as many as 8
(3 motor, 2 power to the hall sensors, and 3 position sense signals).
There are lots of these motors in floppy and hard drives.

Jon