[sdiy] Ladder filter pole

[Theo]

Think triodes are in a way quite similar to FETs.
There are even replacement circuits where a FET (with a little help)
replaces a tube!

Basically a tube diode ladder should be possible too.
Non linearity of the voltage/current relation is what you are looking for
here.

However, not a "real" ladder but could this work?
Chain triodes, anode>cathode>anode>...
Put the signal on top of the anode voltage of the first triode
CV to the gate grit, filtercaps between the tubes.
Take the output from the filter caps, buffer with triode (or opamp).

Just a thought.

Theo


From: Tim Ressel <madhun2001 at yahoo.com>

> It occurs to me that the diodes/transistors in the
> ladder are acting as current-variable resistors. I
> don't know enough about tubes to know if they would
> work in that mode. I know fets kinda work like that.
>
> Hmmm ... time for Group Brain Mode!!
>
> --TR
>
> --- epeasant at telusplanet.net wrote:
> > I was hoping that somebody would design one with
> > tubes, but it might need more
> > than 300V. Diode tubes ought to work OK, though, and
> > 6AL5's (dual diode) are
> > cheap and plentiful. If I ever get time I may take a
> > stab at it; has anybody
> > ever attempted it with FETs?
> >
> > Take care,
> > Doug
> >
> > ______________________
> > The Electronic Peasant
> >
> > www.electronicpeasant.com
> >
> > >Gene et al,
> > >
> > >I can't help but wonder if one could build a ladder
> > >filter out of tubes? I think it'd take a +/- 300V
> > >power supply to put that many tubes in a stack. Or
> > >would one use diode tubes in the middle?
> > >
> > >Hmmm....
> > >
> > >--TR
> > >
> > >--- Gene Stopp <gene at ixiacom.com> wrote:
> > >> One thing that bugs me about CEM-based poly
> > machines
> > >> is that they sometimes
> > >> sound "too perfect", almost to the point of
> > sounding
> > >> actually thin.
> > >
> > >
> > >__________________________________________________
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>
>
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