[DIY] RE: PAIA multiplying DAC, was My new VCO

[Donald Johnson]

From:           	jh <jhaible at primus-online.de>
To:             	"'Donald Johnson'" <djohnson at mdsi.bc.ca>
Copies to:      	"'DIY'" <synth-diy at mailhost.bpa.nl>
Subject:        	[DIY] RE: PAIA multiplying DAC, was My new VCO
Date sent:      	Thu, 3 Jun 1999 12:08:18 +0200

> Is this online somewhere ?

 Don't think so, but ...

 I have the original PAIA article and assembly manual for the DAC
 circuit, but I think that John Simonton of PAIA needs to let us know
 whether I could make scans available.
 
> JH.
> 
> PS.: For monophonic keyboards, basically 3 fixed resistor values (unlike
> one value for V/Oct) works - there is a Korg patent for that.
> 
> -----Original Message-----
> From:	Donald Johnson [SMTP:djohnson at mdsi.bc.ca]
> Sent:	Thursday, June 03, 1999 3:31 AM
> To:	synth-diy at mailhost.bpa.nl
> Subject:	PAIA multiplying DAC, was My new VCO
> 
> jh <jhaible at primus-online.de> wrote:
> >>Very interesting stuff. Now all we need is a 14/16 bit multiplexed DAC.
> >
> >Not sure about that. There was an interesting article from Paia's John
> >Simonton in Electronotes (#61, if memory serves) where he shows
> >how to do it with a (very special) discrete 6-bit DAC. 
> >The idea looks brilliant: changing the gain of 3 opamp stages with
> >6 electronic switches, so you get a scaled multiplication
> >(where you have addition in a normal DAC). John ?
> 
>  Sure, the 4700 replaced the keyboard CV trimmer array with a diode
>  'matrix' which drove a 6 bit multiplying DAC. The DAC circuit used a
>  laser-trimmed (?) resistor set. Cool idea. Works well. My 37+ trimmer
>  key 'exponential-keyboard' became trimmer-less.
> 
>  don.

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