voltage-controlled-Sallen-Key-Filter

[Parkchemiker]

In 1955 the Sallen-Key Filter was invented. There is a 3-pole-Sallen-Key Filter as
lowpass filter. You can find schematics online.

I made a tunable 3-pole-Sallen-Key lowpass filter. 3 matched NJFETs (BF256, J111, J112, J113 or other) could be used.

For matching the NJFETs you need a suitable matching circuit. You can find this online somewhere.

This voltage controlled 3-pole SK-lowpass has a nice sound.

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[Cynosure]

This is cool. Thanks for sharing. It looks similar to the Korg 35 filter (early Korg MS-20).