Buzz Box Issues

[Devius]

Hey,
I'd like to start off by saying Wow. The inexhaustible amount of information you guys have accumulated and shared is awesome! Thanks for creating this resource.
I'm fairly new to the diy pedal gig but I love it. So far I've built an easyvibe (although you hear the pulsing throb of the lfo), the nurse quacky, and a few buzz boxes.
Now, the issue I'm having with the buzz boxes is I'm getting some extra gnarly sounds out of them. Intermittent feedback as well as when I stop playing some rumbles. I mute the strings and that usually stops it but *shrug* I'm somewhat at a loss to figure out why its doing it. It also seems to be picking up an almost timer sound, similar to an lfo type sound.
Any help would be greatly appreciated.

On the design front, I'd like to incorporate a dpdt on/on switch to be able to switch between the buzz box and bazz fuss. I sort of think I know what to do but since I am posting I figured I might as well ask about that as well. Thanks in advance!

[Devius]

I've also wired the pedal up according to the www.BeavisAudio.com website that has a dc adapter and a 9v. I don't know if this is the best way to do it but so far its the only way I've seen.