Re: [CAD_CAM_EDM_DRO] Balls in tube DRO Resolver to Digital

----- Original Message -----
From: "Jon Elson" <elson@...>
>
> The tube would have to be completely transparent to the AC magnetic field,
and I'm not at all clear on the geometry of the exciting winding and the
sense windings. They would need to produce a very accurate sine wave
variation in sensed signal strength as the read head was moved, or the
interpolation will not produce accurate position information.
>
Just a guess, but I don't think the Newall design relies on interpolation of
a pure sine wave. The tube appears to be stainless which is not
magnetically transparent. Accurate representation of the sine wave might
also depend on the construction of the exciter/receiver unit.

My next guess is that Newall has developed some means of curve-fitting the
signal. I recall that LVDT's must be calibrated before use and are only
linear over a very small portion of their travel. The ball tube transducer
looks like an LVDT that operates over more than one period.

Doug