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Feedback Slam Mod on the Sea Urchin?

Started by bajaguy, November 08, 2013, 07:40:07 PM

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bajaguy

I've been looking at trying to incorporate the slam mod used on the echo base to give me that fat self oscillation on my sea urchin at the touch of a momentary contact switch, but so far all of my attempts have come up short. The echo base uses a 20K resistor above the feedback pot that they put the switch across for the mod, but that isn't on the sea urchin schematic. Any idea how I would incorporate thid mod into my urchin?

Baja

rullywowr

I would try using a momentary switch on lugs 2 and 3 of the feedback pot.  This will put the feedback up to 100% when the button is pressed and therefore start self oscillation.



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midwayfair

The best way to do this is to have the momentary connect lug 3 to the intersection of R16 and C5. Put a trim pot in between to dial in how fast it ramps up.

Doing it this way lets the slam switch work completely independent of the position of the Feedback control and also works at zero on the feedback pot ... Otherwise signal is dumped to ground by C12.