[sdiy] state variable filter oscillating

[Magnus Danielson]

From: mark s <djarum11 at mindspring.com>
Subject: [sdiy] state variable filter oscillating
Date: Sat, 19 Jun 2004 22:29:50 -0400
Message-ID: <6.0.3.0.2.20040619222641.037a1600 at pop.mindspring.com>

> hi, i've built a state variable filter with a TL074 and an SSM2164. it is 
> oscillating like crazy when i turn my frequency up above, oh i dunno 6000Hz 
> *and* when the resonance pot it turned way up. without getting deep into 
> the circuit itself, are there some basic principles i should look for in 
> order to troubleshoot ?

Make sure that you twist the resonance pot into a "safe" position, where it
shouldn't selfresonate. Make sure all the feedback paths is working correctly.

Actually, the resonance feedback part needs to work in order for it NOT to
selfresonate!

Schematic would sure help.

Cheers,
Magnus