Correct. That is why the one drawing had a series and shunt fet. To multiplex
audio for stereo generation you have to have tight, clean switching. I also
designed an IFB system when I worked for NPR that also did that. I will
include such a you described for instructional purposes. But for simple
switching, what is shown is more than sufficient. I even switched video with
no image bleeding using the 4066/4051 and eliminating some of the resistors
and capacitors.
Rick

Russell McMahon wrote:

> > I have the site partially up now. I will give you a detailed example of
> your
> > circuit you requested on the same site tomorrow.
> > Pardon the hand scribbled schematics. Will clean them up with Orcad in a
> few
> > days.
> > http://www.pic101.com/audiosw
>
> Switches using a FET as this does or transmission gates (a number of FETs
> inside) can have their isolation greatly improved if needed by adding a
> shorting device across the output (or at an intermediate point). The
> shorting device is switched in antiphase with the enable device.  I had a
> design that used VERY high power levels and that could tolerate only very
> low leakage levels. Using a two part switch as above made all the
> difference. Doing this you may have to pay attention to impedances under
> various switching conditions.
>
>         RM
>
> --

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.