[sdiy] Mux question on SEB's Fat controller

[Samppa Tolvanen]

Hi,

On 7/7/08, Csaba Zvekan <czvekan at gmail.com> wrote:
> Hi,
>
>  I was looking at Seb's Fat Controller design and was wondering if the
> voltage generated by the DAC's output going the mux is being held by the
> MAX306 . Even when you change the mux address? Meaning does it have a sample
> and hold function built in ? Or is the MCU cycling  so fast through all 16
> values that they all appear to be present ?

Look at the schematics closer. Signals from MAX306 go to S&H
sub-circuits. DAC and MUX update times are fast enough, so no
significant drooping happens.

>  And if second , could this principal be applied to a 8-bit mux like the
> 4053/4051 for a smaller Midi to CV version ?

Yes. Many of the 80's analog polysynths used this. Just use fast
enough DAC/MUX update rate and use cap + opamp to keep levels steady.

Samppa