[sdiy] IR3109 (OTA-based) filter question

[patchell]

    This filter chip is similar in operation to the SSM2040 or the CEM3320.  If
you can find data sheets for either of those parts, they will have applications
that should be adaptable to this chip.  If you cannot find the SSM2040 (I am
pretty sure Paul S. has the CEM3320 on his web site), I think I still have the
data sheet and can scan it.

DCMagnuson at aol.com wrote:

> Hi List,
>
> I've got a few questions regarding OTA based VCFs.  I've made a sketch of the
> IR3109-based VCF in the Roland SH-101. (PDF) It's located at:
>
> http://www.hoohahrecords.com/temp/sh101vcf.pdf
>
> It's a series of 4 OTA/Buffer stages...  Basically, I'm curious what is
> possible with this filter.  From what I understand, pins 4, 7, 12 and 15 are
> essentially 6, 12, 18 and 24 dB LP outputs, correct?
>
> Is there a way to change this filter to BP/HP?  Any info or links to relevant
> schematics would be greatly appreciated...
>
> Also, if anyone can supply a little info on how the CV input should connect
> to the gain stages (internally on the 3109 chip), I'd like to add it to the
> diagram
>
> Dave Magnuson

--
 -Jim
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