[sdiy] CV-vactrol circuit

niroke at tampabay.rr.com niroke at tampabay.rr.com
Fri Jul 3 21:45:09 CEST 2015

Thanks for all your replies so far, so glad to actually get through to the list from my phone!

To be more clear, I'm not looking for any vactrol circuit and I'm not trying to build an LPG/phaser/filter.... All I'm trying to do is add voltage control over a variable resistor.  The circuit just needs 0-5V CV input, range and scale trimmers so that I can fine tune each vactrol for the required range, an amp stage (not sure why, tbh), and the Vactrol.... There are a few other bits and bobs in this circuit I've used, and unfortunately I'm not an EE so I can't learn enough from looking at this circuit to go and design something original.   I was hoping there was an old Electronotes circuit that was specifically drawn to perform this task that I could use which would be free from any IP claim.  Of course, something that old may not be as good as something made with modern components.   I admit that this circuit uses an amp IC that I've never heard of or seen used before, and there must be some significance to that.  


---- Julien Delgoulet <jdelgoulet at free.fr> wrote: 
> Alain as one on his moog param eq clone. Just ask him ... 
> http://www.acxsynth.com/parameq/parameqfr.htm
> Le 3 juil. 2015 à 19:40, <niroke at tampabay.rr.com> a écrit :
> > Can anyone direct me to a CV-Vactrol circuit which I can build and make for others which is not bound by any legal restriction?  
> > 
> > I foolishly resigned a currently-available product to suit my needs and for my own use.  I wound up having extra boards made because of a mistake on the first batch (well, there's a mistake on the second batch too), so I have more than I can use.  I wanted to be able to give them away to people building the same project.  I have now asked the manufacturer of the circuit I copied for permission to use the boards, cite him as the origin, and give the extra boards away, and have offered to collect some remuneration as a royalty.  I have not yet had a response, but I figure I should prepare for the worst, and will completely understand if that designer will feel cheated out of income for his IP.  
> > 
> > I already have the schematics, two factory modules, and permission to build clones of Doepfer's discontinued A-101-9 universal vactrol module, but that circuit is a bit more involved than necessary.  Also, I was only given the schematics and permission on the condition that I never share them or build for others.  I'd prefer to use a circuit that I can make available to other builders.  
> > 
> > Anyone one recall a suitable circuit that's free to use?
> > 
> > Thanks,
> > Nick
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