Help creating a tunable oscillator

[Gumby212]

Im trying to figure out a way to make a fuzz circuit (particularly the jordan bosstone) self oscillate for a noisey, feedback option, like the devi ever disaster fuzz. Ive tried applying the technique used for the disaster fuzz to the bosstone, but im too green to understand why its doing what its doing and it doesnt work with the bosstone. Is there a simple circuit that wont add anymore gain i can add after the bosstone to send the effect into oscillation. Id also like to make it tunable. Any help would be appreciated. Thanks!

[abc1234]

How does the Disaster Fuzz create oscillation?

The basic ways to create oscillation are:

• Feed the output back into the input (or a later stage of the circuit into an earlier stage)
• Voltage starve
• Ground starve

Have you tried any of these?

And typically you can tune the oscillation by adjusting the gain or the vol. on your guitar.

[ElectricDruid]

+1 agree with abc1234.

If you've got enough positive feedback in the circuit, it'll oscillate. That's a general truth about all sorts of systems, not just circuits.
The feedback needs to be "positive", so that means you need to make sure that the feedback is in phase with the input signal (so watch out for inversions and phase shifts) and you need enough gain to overcome any losses, although that part shouldn't be a problem in a fuzz. Be aware that it might oscillate at some frequency that you can't hear way up in the ultrasonics, so limiting gain to the audio range to ensure that the feedback and oscillation stay within that range might be a good idea too, if the fuzz doesn't already roll off some top end.

[Gumby212]

Awesome. Thanks for the info guys. Could you explain how occillation works via voltage or ground starve? I understand how to create a voltage starve, but usually to create a dead battery, or gated effect. How can you use this method to create occillation? And im unfamiliar with ground starving. Thanks so much!