<html><head></head><body>I thought i first saw the idea in a National app note, but yes, the Polivoks filter is the most well known (if not the only historic) implementation. <br><br>-Dave<br><br><div class="gmail_quote">On August 23, 2019 12:16:42 PM PDT, David Moylan via Synth-diy <synth-diy@synth-diy.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre class="k9mail">Is this the Polivoks style filter?<br><br><a href="https://modularsynthesis.com/kuzmin/polivoks/polivoks_vcf.htm">https://modularsynthesis.com/kuzmin/polivoks/polivoks_vcf.htm</a><br><br>On 8/23/19 3:09 PM, Donald Tillman wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;">On Aug 23, 2019, at 9:56 AM, Dave <dlmanley@sonic.net> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;">How about the programmable op amp filters based on the lm4250?<br></blockquote> I don't know it. 'Gotta schematic?<br><br> -- Don<br> --<br> Donald Tillman, Palo Alto, California<br> <a href="http://www.till.com">http://www.till.com</a><hr> Synth-diy mailing list<br> Synth-diy@synth-diy.org<br> <a href="http://synth-diy.org/mailman/listinfo/synth-diy">http://synth-diy.org/mailman/listinfo/synth-diy</a><br><br><br></blockquote></pre></blockquote></div></body></html>