[sdiy] CV-vactrol circuit

niroke at tampabay.rr.com niroke at tampabay.rr.com
Sat Jul 4 01:15:34 CEST 2015


Gordon,
I have no experience with anything digital, but if you mean I could have panel settings and midi control over parameters, that could work.  I'd have to have someone walk me through it all.  I was trying to stick with CV because I have a decent-sized modular and several MIDI/CV interfaces including an MCV24.  

Neil,
It was my understanding that the two trimmers in the vactrol circuit allowed one to adjust the CV to only swing to the desired resistance.  Most of the vactrols I've seen go up to several megaohms. 



---- Gordonjcp <gordonjcp at gjcp.net> wrote: 
> On Fri, Jul 03, 2015 at 08:58:51PM +0000, niroke at tampabay.rr.com wrote:
> > I'm trying to add external control to my TR-9090's voice parameters, and I'm sure if that was as simple as patching in to a CV summing point, it would have been done by now.  The 909 circuits don't lend themselves to voltage control.  From what I know, I can control the parameters with a vactrol in series with the variable resistor.  If you have a better solution, I'm eager to hear it! 
> > 
> 
> You could try digital pots, maybe?  Does it *have* to be a control voltage?
> 
> -- 
> Gordonjcp MM0YEQ
> 
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