MFOS VCO Jfet Ringing

[fuzzo]

Hi,

I've just built the MFOS VCO and I have a ringing with the jfet switch.

Like if the Drain/Source path was oscillating before rest (actually is).

I used a 2n5457 without particular care about its On resistance although I think it has nothing to with that. I tried increasing C17 without success. I don't know if it's a real concern or ainherent default of the design Although many pictures of similar design show a glitch free ramp.


http://musicfromouterspace.com/forums.html?MAINTAB=SYNTHDIY&PROJARG=VCO20120618REV0/VCO20120618REV0.html&VPW=1670&VPH=761

any ideas ?

thanks.

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[m.o]

Is there any of this ringing present at the output of U2-B?
Maybe it's the comparator that's bouncing...

[fuzzo]

I thought about that too but the ouput of the comparator is really clean and the Jfet gate as well.