[sdiy] Something better than CD4066 to switch CVs?

chris chris at chrismusic.de
Tue Feb 19 19:09:50 CET 2019


On Tue, 19 Feb 2019 18:35:44 +0100 Florian Anwander <fanwander at mnet-online.de> wrote:

> Am 19.02.19 um 11:06 schrieb Tom Wiltshire:
> > The Prophet 5 managed to switch Oscillator B into low frequency mode about thirty years ago, so it must be possible.
> >
> > I had a look at the schematic and it doesn’t look like they switch an extra cap in though. Instead they switch an extra -15V into the CV. The Pro-1 uses the same trick.
> >
> Someone more knowledged may correct me, but I think this may work with a 
> coarse parameter change, but with tracking sensitive controls, the inner 
> resistance of the 4066 might become an influence.
> 
> Florian



But once you're entering LFO range, IMHO tracking becomes less important.
And I don't think an *open* switch will affect audio tracking.

I agree that using a CMOS switch in tracking relevant areas requires at
least some consideration. Switch resistance may be specified as foggy as
"yes, it's there, and it's something around ^&@&%* ohms at room
temperature".

Christian




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