Mark Rages <markrages@gmail.com> wrote:
> On 7/19/06, Olin Lathrop <olin_piclist@embedinc.com> wrote:
> > Mark Rages wrote:
> > > > 1 - There should be a cap to ground from the node between R1 and
> > > >     R2. Otherwise any supply noise and anything that node picks up
> > > >     is going to end up on the signal.  There should be at least a
> > > >     100nF ceramic, and maybe a 10uF electrolytic too.  A single
> > > >     1uF ceramic is probably good enough.
> > >
> > > But then it won't cancel supply noise from the mic.
> >
> > Right, but then it wasn't doing that before either.
> 
> Why not?

Because the gain on the two paths (inverting vs. noninverting) isn't
anywhere close to being equal.

Isn't that obvious?

-- Dave Tweed
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