Hex VC mixer

[Magnus Danielson]

From: Scott Gravenhorst <chordman at earthlink.net>
Subject: Re: Hex VC mixer
Date: Mon, 24 Jul 2000 10:07:05

Scott,

> Ok, I slapped together a GIF of what I thought Magnus
> was describing.  If someone can take a look at:
> 
> http://home.earthlink.net/~chordman/4049vca.gif
> 
> to verify?  I'd appreciate.  The GIF depicts one VCA.

This is basically showing what I described, except that you missed the
virtual ground output on the Vss pin. See TomG's schematic for an example.

One really needs an virtual ground current to voltage conversion because
otherwise will the CV to Vss voltage vary along side the voltage of Vss and
this is bad since the CV is relative to signal ground but the trannie is
sensitive to the CV relative to the Vss pin, thus the Vss pin needs to be
stuck at the signal ground voltage level, but tapping the current of Vss is
fine so a resistor in a op-amp negative feedback loop and the pos input to
ground is just what it takes.

Then there are ways to use these 4049s as linear amplifiers etc. ;)

Cheers,
Magnus