A very cool sounding ring modulator by Carlin. Have a look at my completed build here. I put a 4.7nF cap between vol lug 1 and 3 (ringmod output - ground) on my build to tame some of the treble a bit.
Now updated with a oscillator daughterboard to make it much more useful. :)
On its own the Carlin Ringmod sounds kinda like a starved octave fuzz. To achieve the typical ringmod effect you have to connect an external tone-generator. Sadly not without the classic ringmod problem - carrier bleedthough (alot in this case). But my daughterboard takes care of that issue.
My idea was to put the tone generator in the box with a in/out switch insted of having two inputs like the original. I also wanted the signal to gate when not playing. This is what I came up with and it's working great.
it's a VCO (voltage controlled oscillator) controlled by a VCA (voltage controlled amplifier), which means that the VCA is triggered by the guitar signal and turns off the VCO when not playing - no more carrier bleedthough. :) The idea came from the Penfold Fuzz Unit circuit thanks to Moosapotamus video and the oscillator is taken from the LM13700 datasheet, modified for single supply and useful freqency range.
All the layouts are Verified unless noted.