two strange happenings with a silicon fuzz face

[ode2no1]

so i built a silicon fuzz face a little while back that i asked you guys for help with because it was just not working properly. somebody pointed me to the dragonfly layout, which does work but if both the volume and gain knobs are maxed then i get a very high pitched oscillation....like ultra high pitched to the point where it isn't even loud. i can turn the gain knob down just a hair and it disappears or i can turn the volume down to about 10 o'clock and it disappears. when the oscillation is present the fuzz sounds pretty normal while playing with my guitar volume full up but if i turn it down to clean up the fuzz it's really crackly and awful sounding. all in all it isn't a big deal to work around these issues so no complaints, but today i noticed that if i touch both bc109's simultaneously with my finger the oscillation is gone. even with both knobs maxed i get no crackly fuzz with my guitar volume knob turned down a bit or anything.  what does this mean? and secondly...and this one is really weird: when playing my deluxe reverb (with reverb on) and the fuzz face is oscillating it completely cancels out my reverb. it's the craziest thing. as soon as i turn the pedal off though the reverb just comes back in.

anyway thoughts? i have no idea what could be causing these things, but you guys are smart as hell haha.

thanks

[John Lyons]

Make sure you use short wires to the input/output and to the switch (as best you can).
Also make sure to keep the input wire physically away from the output as much as possible.
Putting a cap from the input to ground can help as well. Try .001 up to .01.

John

[ode2no1]

thanks a lot. i tried keeping all the wires pretty short, but there's probably a little more trimming i could do. does adding that cap from input to ground affect the tone of the pedal at all?

[nbabmf]

I used a 1000pf cap from input to ground and it got rid of all the crackle when I turned the volume down on the guitar.

[Brymus]

I too had the same issue.(well with the TBMKII,its still a fuzz)
Look at my take on RDV and Dragonfly's Si TBMKII
I got rid of the oscillation by lowering the value of the degenerative cap on the emiter,IIRC by just 1uf or so lower,
http://www.aronnelson.com/gallery/main.php/v/Brymus/Tonebender+MKII+Pro+Si/Si+Tonbender+MKII+Pro+Zep+Version.gif.html

[blueduck577]

I had a similar issue with a silicon FF built on the breadboard... if I recall correctly I put a smallish (~100 pF?) cap between the collector and base of Q1 and it fixed the oscillation quite nicely.