Design of VCFs

[Sean Costello]

At 07:47 PM 11/25/96 -0500, you wrote:
>

>My circuit consists of a JFET for variable resistance, an opamp and some
>resistors and caps.  Any suggestions?  DOes anybody know of any interenet
>sites that have schematics for other vcfs?

You might want to look at the Moog ladder filter design that Rick Jansen has
at http://www.sara.nl/Rick.Jansen/Emusic/Moog/moog-e.html.  Another ladder
filter design, a diode-ladder filter similar to that of the EMS Synthi, can
be found at http://www.seanet.com/~costello.  Mikko Helin has a state
variable filter design at http://www.uta.fi/~helin/index-sch.html.  All of
these should work for the characteristics you want, although they are
considerably more complex than the filter you describe.

Good luck,

Sean Costello