Re: [sdiy] Digital Pots

[Roman]

what I think Jeff wants to achieve is to put digital pots in the 808, and not in the MIDIbox, what BTW would make not much sense.
To control the digipots in 808 one would need some kind of MIDI translator, that would convert MIDI CCs into serial interface of the pots.
With recently introduced +/-15V capable digital pots now it's easier than ever to put MIDI control everywhere.

Roman

---- Wiadomość Oryginalna ----
Od: Heitor Alves <heitor.alves at gmail.com>
Do: Jeff Farr <moogah at gmail.com>
Kopia do: synth-diy at dropmix.xs4all.nl
Data: Thu, 4 Aug 2005 13:01:31 +0100
Temat: Re: [sdiy] Digital Pots

> Hi Jeff
> 
> I remember looking to that solution too, the digital pots, but TK as
> told me on the forum that its better to use encoders than pot's
> (analog or digital). i'm going to try to find that post and let you
> know.
> 
> Regards
> 
> Heitor
> 
> On 8/4/05, Jeff Farr <moogah at gmail.com> wrote:
> > SO, while scouring the net for a way to connect a MIDIBox SEQ to a 808
> > clone so that all the parameters are digitally controlled I've come
> > across a series of IC's at analog devices and maxim-ic called digital
> > potentiometers.  There is a large variety of them in many different
> > resolutions, of specific interest are the ones with 127 possible
> > values.  Has anybody tried to use these as an in between from encoders
> > + digital interface to regular VC circuits?  Some of them are 2
> > terminal and are listed as , but others have three which would seem
> > ideal.
> > 
> > Quote from site:
> > "The AD5247 provides a compact 2 mm x 2.1 mm packaged solution for 128
> > position adjustment applications.
> > 
> > This device performs the same electronic adjustment function as a
> > mechanical potentiometer or a variable resistor. The low temperature
> > coefficient makes this device ideal for high accuracy and stability
> > variable resistance adjustments. "
> > 
> > <a href="http://www.analog.com/en/subCat/0,2879,761%255F797%255F0%255F%255F0%255F,00.html" target='_blank'>http://www.analog.com/en/subCat/0,2879,761%255F797%255F0%255F%255F0%255F,00.html</a>
> > 
> > <a href="http://www.analog.com/en/prod/0,,761_797_AD7376%2C00.html" target='_blank'>http://www.analog.com/en/prod/0,,761_797_AD7376%2C00.html</a>
> > 
> > Seems with such a selection there should be at least one that will
> > work.  There aren't alot of available resistance values, but if I'm
> > not mistaken I can place it in parallel with a regular resistor to
> > achieve the desired range through 1/Rt = 1/R1 + 1/R2 etc.
> > 
> >
> 
>