Hi Ingo,

> Even though the
> filter itself is rather smooth sounding the self oscilation comes all
> of a sudden

I'd be quite happy to cast an eye over the circuit to see if I can come
up with a suggestion as to how to change this, but unfortunately I
don't actually have this module and so do not have access to the
schematics, so unless someone can send me a copy ... Dieter Anyone

Tim