Not sure if this has been posted already, but I though it was worth sharing. See attached PDF.
The guy used a Analog Devices AD633 Four Quadrant Analog Multiplier to do the heavy lifting. Could be a jumping off point for a new pedal project.
Hey CJ,
I was looking into this a while ago. from what I remember there were issues with the oscillator making noise even when bypassed. If there is a solve for that now I'd be interested to see how it works. There were a few others (ring mods) that were pretty interesting. The John Hollis one (The Forbnicator) and the Thing Modulator. Those two seemed more stable but the ICs for all are getting more and more scarce.
The String Ringer project wound up having mods that turned the power to the oscillator off entirely, when not in use.