VCF

[tomg]

> In this circuit there are a 10K from the output (pin 8 on LM13600) to
> -12 v. http://www.geocities.com/efm_gc/cbook/pics/vcf8b_sd.gif
> Should I also have a resistor from the output of the TL072 to -v?

No..It's only for the 13600's buffers. I saw your post the other day
but had my head so far into the new VCO I couldn't answer. It sounds
like the filter is wired correctly ...you are passing audio??  Only the
cutoff doesn't work so concentrate your efforts there. I think  the
second pnp is working because audio goes through the filter. I don't
think the first pnp is doing the job for some reason. Look around
here carefully, maybe replace the transistors.

> http://www.itn.liu.se/~nikro/littleman/vcf.gif
> In the circuit with the LM13600 there is only a 10k pot for resonance,
> in the other circuit there is a 2.2k resistor and the 10 pot... What
> does the 2.2k resistor do? Do I have to use it?
> I think both circuits come from Tom, so maybe he knows the answer?

The 13600 version you are looking at was a special version I did trying
to get the MS20 ESP working. As it turned out I did something else
all together. Don't worry about it.  The one you are trying to build is fine
like it is.

Niklas, DO NOT take this wrong but I have to say something about you
appropriating my graphics for your page. That's bad form. I might as well
give you permission to use the graphics you have but don't do it again
and for sure don't do it with someone else's work.

You can redraw anything ( of mine or anyone else's ) and display it on
your page. Just replacing the text doesn't count. Nice try though...;-)

Tom