"Sewer Pipes Ring-Verb" Simple PT2399 One-Knob Effect

[Cilantro666]

Just built this but I noticed it doesn't work well with other pedals. Sometimes it works and sometimes I just get loud oscillation. Also if I plug in my guitar, halfway I guess this is just to ground I also get a very oscillation. I'm wondering if I have it wired wrong although I don't think so. I'm getting a bread board today and going to try to start over and see where I get. I like noise and I like loud so I'd like to try to be able to use this oscillation predictably

[ElectricDruid]

Welcome Cilantro!

Can you post the circuit you used? The original schematics from this thread have all disappeared for me (it was a while ago, let's face it.. )

Getting a delay circuit to oscillate isn't generally too hard, but like you say, it helps if it's predictable, and it shouldn't happen all the time. That would be a fault.

[bluebunny]

Here's the original schematic that David posted:



This is one with the optional resonance control in-circuit.  Not sure who drew it.

[noisette]

This is a really funky circuit, I think it came about more by tinkering than proper circuit design (which isn´t a bad thing necessarily, Fuzzface comes to mind!), but iirc you have to experiment a bit until it fits for you.
The basic idea is to modulate the delay time with the ac audio signal, there´s a lot of possible interesting configurations if you play around I think you will not be disappointed!

[duck_arse]

C6 is shown backwards.

[Cilantro666]

This is the layout I used. I replaced the 33k the first one to 10k

[duck_arse]

the 10uF at the input on that layout is backwards, even tho it has no pulldown resistor on it. as shown, the (-) of that cap will have the +2V5 or so from the PT2399 internal opamps bias, and the (+) of the cap will be [either grounded via a pulldown resistor or] connected to your pickups [or preceeding fx, with pulldown on output] which will have 0 DC Volts. hence, backwards.

[bluebunny]

^^ Quite right.  My own layout (ancient history) also had the same mistake.