[sdiy] CV-vactrol circuit

David G Dixon dixon at mail.ubc.ca
Fri Jul 3 20:21:05 CEST 2015

They're all free to use, as far as I know.  No one will have had an active
patent on any of these circuits for many years (if ever), and beyond that
there is no legal protection for a circuit design.  The thing preventing
people from just copying other people's circuits is common courtesy and
mutual respect.  However, general vactrol circuit schematics have been in
public circulation for so long that I doubt that anyone has a compelling
moral claim to them.

Others may disagree.

> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of 
> niroke at tampabay.rr.com
> Sent: Friday, July 03, 2015 10:41 AM
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] CV-vactrol circuit
> 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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