Bobtavia help!

[aestoval]

Hi,

I'm pretty new here, just recently started making my own pedals and I'm going through some steps with this Bobtavia to figure out what's goin' on.

I built it, troubleshooted until it got to be working (by the way great effect) but I'm having some problems with what seems to be oscillation.  Sometimes when the pedal is cranked and I hit a low note loud, it starts to go berserk, and very little will stop it.

I did the cap on the guitar plug into the amp test and found it was happening on the output of the IC (pin 5).  I used a socket so I didn't think I could have fried it, Could it be faulty?

Tomm. I was gonna pop into RS and get another IC and see if it helps my problem.  I also read in another post some one was having problems with the effect sounding like their speaker was blown out. This sounds familiar...

Anyway, if anyone else has had problems with this let me know if you found a cure (maybe an internal trim to control the max level?).

Thanks

Atticus

[petemoore]

(maybe an internal trim to control the max level?).
  when you turn the knob theres a resistance introduced between it's wiper/outside lug, if you want that to be 'max' measure the resistance introduced, then put a fixed resistor on that outside lug of the pot.
  Since I didn't look at the scheamtic this may give a good idea or wrong...

[aestoval]

Well, looks like the problem fixed its self. I have found that oscillation mainly is a problem when there is either an unregulated power supply hooked up and seems to be cured when both a regulated supply and battery are hooked up simultaneously.

Thanks for all of the help. Hope this helps others with the same problem

Atticus

[DougH]

Did you put a filter cap from 9v to ground in your circuit? That will help clean up dirty power somewhat.