[sdiy] Crosspoint Switch [was: Which programable chip?]

[Joe Grisso]

Sorry to jump in like this, but using the 405x in current mode was
discussed in the last thread. Check out this reference:

http://www.dself.dsl.pipex.com/ampins/mixer/mixerdes.htm#7

You wire the switch in between Ri on the op-amp and the inverting
input, which turns the voltage presented on the other side of Ri into
a current flowing through the inverting input. It's that virtual
ground, man! ;-)

-- 
Joe Grisso
Detachment 3 Engineering


On Fri, Apr 17, 2009 at 8:55 AM, Ian Smith <taciturn_unquiet at hotmail.com> wrote:
>
> I'm not sure I'm seeing what you see Eric. I'm seeing the input still going through the 4051 and the output going to the opamp so the input still has to go through the 4051. Maybe I'm misunderstanding what you're saying.
> -Ian