[sdiy] Good 24db/oct HP-LP-BP-Notch filter Schematics ??

Mattias Rickardsson mr at analogue.org
Thu Mar 6 15:56:24 CET 2014

On 6 March 2014 12:48, Neil Johnson <neil.johnson71 at gmail.com> wrote:
> Mattias Rickardsson wrote:
>> Is the schematic of your 3-pole SVF available perhaps, as a
>> comparison? The link is broken. :-)
>> http://www.milton.arachsys.com/nj71/index.php?menu=2&submenu=0&subsubmenu=1
> Yes the link is broken.  If anyone wants a copy they can ask, but
> following the suspected actions of a certain company I won't be
> providing schematics online of anything I might one day want to
> release as a commercial product.

I see. Perhaps you'd want to check out the non-broken link on this page as well:

> But yes, a 3-pole SVF extends the 2-pole form, adding a third pole
> which sits on the real axis.  Adding a fourth integrator adds one more
> pole, so giving two conjugate pole-pairs.  It is the damping that gets
> "interesting".

I remember now that I've seen those 4th order SVFs in the past.

/mr  -  getting old :-)

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