[sdiy] CV-vactrol circuit

[Richie Burnett]

500ms sounds incredibly slow.  The AD5160 that I'm currently using for an 
industrial project has 256 discrete levels and a quoted settling time of 
1us, for about 1USD a piece.

You do have to be careful with the number of updates for some digi-pots with 
built-in non-volatile storage though, as the number of write cycles to the 
storage part might be limited to something like 100,000 operations.  You can 
go through those quite quickly if your update rate is 10kHz! ;-)

-Richie,


-----Original Message----- 
From: Sean Ellis
Sent: Saturday, July 04, 2015 12:54 AM
To: Richie Burnett ; Gordonjcp ; synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] CV-vactrol circuit


Aren't they quite slow at updating? I looked at one that had a horribly slow 
maximum update time of something like 500ms (with few discrete steps between 
full on and full off).


> From: rburnett at richieburnett.co.uk
> To: gordonjcp at gjcp.net; synth-diy at dropmix.xs4all.nl
> Date: Sat, 4 Jul 2015 00:18:30 +0100
> Subject: Re: [sdiy] CV-vactrol circuit
>
> Digital pots sound like a better idea to me. If you add a low-end
> micro-controller you can have the choice of either CV control or MIDI
> control.
>
> -Richie,
>
>
> -----Original Message----- 
> From: Gordonjcp
> Sent: Friday, July 03, 2015 11:46 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] CV-vactrol circuit
>
> 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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