Re: [CAD_CAM_EDM_DRO] Simple DRO new idea

"M. SHABBIR" wrote:

> hi
> u can find ring magnet in back of audio speaker.
>
> shabbir
>
> At 02:26 PM 9/2/01 -0600, you wrote:
> >Scott
> >I am working on a very simple dro using a special purpose Hall effect sensor
> >and a simple up down counter connected to a 8 digit led. It would work as
> >follows
> >a linear magnet strip or a ring magnet with alternating north and south

The ring shaped magnet it a speaker has one pole in the center, and one pole
on the OD (some fold the design, so each face is a pole). This won't work
as a magnetic encoder, since the poles don't move when it is rotated.
A 2-pole motor with a ring magnet only has 2 poles for one revolution,
so that may still not work well for your application. Floppy drive motors
from the ones with the motor in the hub usually have more poles, and may
have a tach ring that has many poles per rev. These are pretty large
diameter, however.

Jon