[sdiy] Audio taper pots - shunt resistors and contact resistance

[Ove Ridé]

On 8 September 2012 23:35, Matthew Smith <matt at smiffytech.com> wrote:
> Quoth David G Dixon at 09/09/12 06:52...
>
>> V2164 in quantities is about $1 per chip, and you get four high-quality
>> VCAs
>> per, about 25 cents per VCA.  With this, the pot doesn't need to be
>> anything
>> special, since it's just going to be sending DC to the control circuit.
>> THAT Corp. dual VCAs are a bit more, but still, it's cheaper than buying
>> fancy pots, and you avoid bringing audio to the panel.
>
>
> <thinking_out_loud>
>
> Be handy to have a hybrid - DCA, in the form of an analogue VCA with an
> on-board DAC to provide the control voltage. I guess the trick would be just
> to make a little board with VCA + DAC that fits a DIP land-pattern. Real
> analogue VCA, with SPI control. If V2164's are cheap in quantity, DACs are
> even more so.
>
> </thinking_out_loud>

Some people may worry about noise from a digital circuit (for example
through stray capacitance) and may want to keep them apart. It may
also be that the semiconductor processes used for a typical DAC and a
"high" voltage (as opposed to 3.3 V or 5 V) VCA are incompatible or
difficult to combine without a lot of additional R&D. Feel free to
prove me wrong.

-- 
/Ove

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