[sdiy] Pot-based SVFs
tom at electricdruid.net
Thu Mar 13 15:45:53 CET 2008
The Analog Devices interactive filter design tool (needs java) will
give you a schematic for a state-variable filter, among others. Great
tool, actually. I'd mention it in a lecture anyway!
Hope this helps,
On 13 Mar 2008, at 06:47, Aaron Lanterman wrote:
> Tomorrow's lecture is on State Variable filters.
> I have examples to show from the Oberheim SEM and the EML-101,
> which I understand fairly well.
> I'd also like to show a couple of real-world examples of non-
> voltage-controlled SVFs - i.e. ones controlled with regular pots -
> before I dig into the voltage-controlled ones. I'm looking for
> something with a real-world world schematics, i.e. not idealized
> textbook schematics. Any ideas?
> I ran across this design by M. Danielson:
> But something doesn't look right to me. Both feedback loops should
> be negative, if I understand the universe right; going through two
> integrators and then into the - input of the op amp maps sense to
> me, but taking the output of the first integrator and running it to
> the negative doesn't, since that looks like positive feedback. I
> think it should be going to the positive terminal of the first op amp.
> The initial input is going into the negative terminal, but that's
> Is there something I'm missing?
> - Aaron
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