Sea Urchin feedback not working...

[Willybomb]

I'm just following this because I had a run of one repeat PT based delays, usually the smaller ones.

[pgodfrin]

I've taken a break on the sea urchin as I was close to finishing another board, which of course if giving me problems. Grrrrrrrrr

[pgodfrin]

Howdy folks,
Got back to the urchin, it works! It works too much! With the feedback pot turned all the way counter clockwise, now I get lot's of repeats, too many!
Any help is appreciated..
thanks

[jimilee]

You mean it oscillates?


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[pgodfrin]

Well not exactly. When the feedback knob is fully counter clockwise, I get like 10-15 repeats. If I turn it up, it self oscillates at about 1/3rd of the way up...

[jimilee]

Have you checked you resistor values yet?


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[pgodfrin]

good point. I'll get back to you

[madbean]

Well not exactly. When the feedback knob is fully counter clockwise, I get like 10-15 repeats. If I turn it up, it self oscillates at about 1/3rd of the way up...

You should only have one repeat full CCW. Something has gone wrong! Possibly lug1 of your Feedback pot is not properly connecting to ground.
The resistor that controls the self-oscillation point is R14 (5k1) and can easily be bumped up to 12k.

[pgodfrin]

OK - that's good advice too. The resistors check out. I'll look at the ground on that pot too.
thank you!

[pgodfrin]

Thanks for the help folks. In the end, the B50K pot was bad. Replaced that and we're good to go!
woohoo!