[sdiy] IR3109 (OTA-based) filter question

[mark verbos]

DCMagnuson at aol.com wrote:

> In a message dated 5/18/01 12:15:33 PM Eastern Daylight Time,
> marmot1 at magma.ca writes:
>
> > The Roland JP-6 has a multi-mode HP/LP/BP VCF which apparently (I don't
> >  have the service manual) uses the IR3109. The IR3109 is  used in the
> >  JP-8 VCF which has selectable 2-pole and 4-pole LP modes. The Roland
> >  (Boss) RPH-10 phaser uses two IR3109 for the allpass filters. I have the
> >  RPH-10 schematic and can send it if you wish.
>
> I've figured out the 2-pole/4-pole switch, and thanks to an earlier reference
> to the CEM3320, I believe I've figured out the HP/LP/BP switching as well...
>
> I'm currently trying to decide on the best method if implementing the
> switching, since I'll be making/breaking several connections simultaneously.
> I'm probably going to use 4016/4066 analog switches unless someone has a
> better idea
>
> Dave

the problem lies in powering them. You need to make a +/- 7.5volt supply just
for the switching chips.

The Buchla solution was the LF13331 switching chip. They can be powered from +/-
15 and will switch from almost anything ( threshold at 2 volts). There are 4
switches in one 16 pin package.

These are really hard to find these days and quite expensive if you do. There is
also the DG201/202 and DG441/442. Any of these would be suitable for your
application.

These may all be overkill, but they are the best part for the job.

--
mark verbos

"if you want something done right, build it yourself."

verbos at simple-answer.com
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