[sdiy] Hi / search? / programmable resistor for VCO?

Ullrich Peter Peter.Ullrich at kapsch.net
Tue Jan 7 09:46:47 CET 2014


Have a look at this one:
http://www.ti.com/lit/ds/symlink/lm1972.pdf 

The LM1972 is a digitally controlled 2-channel 78dB audio attenuator fabricated on a CMOS process.
Each channel has attenuation steps of 0.5dB from 0dB-47.5dB, 1.0dB steps from 48dB-78dB, with a
mute function attenuating 104dB.

Ciao
Peter

-----Ursprüngliche Nachricht-----
Von: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] Im Auftrag von Roman Sowa
Gesendet: Dienstag, 7. Januar 2014 08:55
An: synth-diy at dropmix.xs4all.nl
Betreff: Re: [sdiy] Hi / search? / programmable resistor for VCO?

try to look for "digital audio attenuators". I'm sure there are models with 0.5dB/step response, which is exactly what you need for a keyboard.
Well, you need about 0.502dB/semitone but the chips will be much less precise than that anyway.
Another option is to place at least 12-14 bit DAC in each VCO and control them via look-up table by microcontroller.

Roman

W dniu 2014-01-07 05:24, cs80 at therogoffs.com pisze:
> Hi all.
>
> Thought I was already subscribed here but I guess not.   I have an
> idea/questions about a digitally controlled resistor for a VCO.
>
	<snip>
>
> Any ideas on this?  Anyone know of parts like the AD but with exp/log 
> response - maybe designed for audio use / attenuators?  Any more 
> knowledgable info on resistor ladders?
>
> Thanks much for any ideas and/or pointers!
>
> Happy Analog New Year!
>
> David
>
>
> _______________________________________________ Synth-diy mailing list 
> Synth-diy at dropmix.xs4all.nl 
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>
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