Filters, and a ? for Mariss was Re: Rotor inertia.

Hello,

Poles in a filter relate to the slope of the "filtered" output. A
single pole filter has a 3db drop off for a halving (or doubling) of
the input frequency from the filters' designed "center" freq.

2 poles is 6 db slope, and 4pole is a 12db attenuation slope. In
other words, the more poles a filter has, the more strongly
frequencies outside the designed "center" frequency will be rejected
from the output.

As Jon wrote, one pro is that filters "slow things down". This means
that fast changing things like noise are rejected, whilst the good
stuff gets through. There was a recent thread on the xylotex yahoo
group about using a simple r/c filter in the step line to prevent
spindle motor noise from falsely stepping the drive. There was enough
technical (simply worded, and presented) over the course of the
thread to be worthwhile if you wish to understand a bit about how and
why filters might be used...

As to a filter improving a gecko; I'd bet Mariss has already covered
that base!

Hope this helps,

Ballendo

P.S. Mariss, you said recently that it's okay to ask you how you do
things... You've explained the theory of stepper mid-band
stabilisation a few times; would you explain how you accomplish it in
your drives, circuit wise? Thank you in advance.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "ajv2803959"
<antonio_ximenez@h...> wrote:

> John could you explain, about 2 pole filter.
> What is it ? A integrated component (what is the reference) or is an
> schematic.
> What are the pros in using this filter vs not using ?
> Looks like a simple improvement, in geckos.
>
> Thanks in advance
>
>