[sdiy] Re: [AH] looking for schematic for dual vco

[Magnus Danielson]

From: cacofone <pulse8 at goodtimetribe.com>
Subject: [AH] looking for schematic for dual vco
Date: Sat, 25 Aug 2001 03:14:03 -0500

> Hello, looking for a current (doesn't use CEM3340) Dual VCO, where I can 
> mix the VCO's (i.e. Pulse/triangle etc)
> 
> Or, if I've got two VCO's, how do I mix the two? With an op-amp?
> 
> looking for more details...

This is really an Synth-DIY list question... but anyway:

Take an op-amp. Hook the (+) input to the ground. Hook in a resistor
(say 10k Ohm) between (-) input and the output. Connect your input
signals through resistors (say 10k Ohm again) to the (-) input.
This will give you a summing of the signals (VCOs or whatever) on the
output. You should be aware that the signal is inverted, but maybe you
don't care.

If you want level controls, just damp the signals through pots and
hook the tapper through the input resistors.

Hope that came out clear.

Cheers,
Magnus