Standalone VCF as an effects box?

[Arthur Harrison]

I have a simple +/-12v supply shown at:
http://home.att.net/~theremin1/ez/power.htm
and an associated parts table at:
http://home.att.net/~theremin1/ez/parts.htm

This supply should be adequate for small analog
projects using a few ICs.

The transformer specified is a little unusual in that
it has a ground terminal.  This ground was required
for the specific application, but can be eliminated
in many instances.  I believe that Digi-Key Electronics
has a variety of 12vac plug-in transformers that will
work in substitution.

-Art

-----Original Message-----
From: Michael Rogers <mike at p-w-m.demon.co.uk>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Tuesday, November 24, 1998 2:00 PM
Subject: Standalone VCF as an effects box?


> I'm new to synth building and electronics in general. I have a little
>bit of knowledge from school and gleaned from various sites on the web,
>from reading this mailing list, etc. and I'm interested in building my
>own synth modules/fx gear for making experimental industrial music. 
>
> The first project I plan to undertake is a PWM design from a UK music
>magazine (it uses a Schmitt trigger to convert an audio signal into a
>square wave), for use as an extreme distortion box. I might put some
>tone control on there too, depending on how versatile the output sound
>is. My second, more ambitious project is a VCF effects box, probably
>based on the EMS diode ladder filter. The idea is to have a wah-wah type
>pedal controlling the cutoff, and the Q control on a trailing lead so I
>can tape it to my guitar/mic/etc.
>
> I've got a few questions I was hoping someone could help me with:
>
> All the designs I have found for VCFs (including the excellent but
>complicated standalone VCF effects box at http://aupe.phys.andrews.edu/d
>iy_archive/schematics/effects/filter.html) have control voltage inputs.
>Can I just leave these unattached, and will the cutoff and Q controls
>still have their full range?
>
> The VCF designs I've found require between +/- 9v and +/- 12v DC. Is
>there a commercially available AC adaptor that can give out these kinds
>of voltages, or am I better off building my own PSU? If I have to build
>my own, does anyone know of a good (easy!) design that's up on the web?
>
> Lastly, has anyone built a PWM and tried it with an audio signal input,
>and is it worth pursuing?
>
>
>Thanks in advance,
>
>Michael Rogers