TMK FUZZ troubleshooting

[dasoner]

Greetings, nice to see ya all
I recently made a TMK fuzz pedal http://gaussmarkov.net/wordpress/circuits/tmk/ and some things i observed seem a little weird..
When i plug the pedal I/O normally it operates pretty much as it should, i believe.
But when i tried to connect the pedals INPUT as a source to my soundcard, just to see what happens there, i observed that when i tweaked some settings (feedback/input impedance/gain color to high values mostly), i can hear and see a pulse-like signal or self osc (again, coming from the pedals input) which changed frequency with tweaking.
I measured something like 3 volts max with a multimeter (DC if i remember correct).
When i switch it to normal connection i have no obvious problems with the sound, in fact it sounds pretty solid and dynamic on 909/808 drums, but knowing that voltages and signals appear at the input scares me a bit..
Do you think this is normal? Could it be some modulation signal?

Best regards,
DAS

[dasoner]

solved