MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

Transistor Superladder always self oscillating. (Fixed)
MUFF WIGGLER Forum Index -> Oakley Sound Systems  
Author Transistor Superladder always self oscillating. (Fixed)
ApeIslandSound
Hello! I've had a good week for Oakley builds. Six modules assembled, with five working perfectly.

The transistor superladder is behaving strangely though. It's like the resonance is always cranked. Always self-oscillating. Freq range is good, and all else seems pretty happy, just full resonance all the time.

So I've gone wrong somewhere. The most obvious error could be that I ran out of TL072's, and subbed TL082's for all eight of the 8pin IC's. Could this be the source of the problem? I've often done this sub in the past, and haven't had any issues.

Thanks!
ApeIslandSound
Update: I swapped the TL082's for TL072's. I also tried a new LM3700. No change in behaviour.

Solder joints seem fine.

The resonance does not respond at all, neither by pot or CV.

Also, just for the record, this is 1U, non-buffered.
Synthbuilder
Could be quite a few things unfortunately. But my first thoughts would be to make sure Q7 is a BC560 or BC559. Secondly I'd look for solder shorts around the pins of U10.

Tony
ApeIslandSound
Thanks Tony. Will do.
ApeIslandSound
Tony nailed it.

Q7.

A rogue 3904 somehow ended up in my BC559 drawer. I'm pretty thorough about checking every component before installation, but this one slipped through.

Thanks again Tony.
MUFF WIGGLER Forum Index -> Oakley Sound Systems  
Page 1 of 1
Powered by phpBB © phpBB Group