"Eeyore" <rabbitsfriendsandrelations@[EMAIL PROTECTED]
> wrote in message
news:486C4867.F6DAF534@[EMAIL PROTECTED]
>
>
> Bob Eld wrote:
>
> > "Eeyore" wrote
> > > Bob Eld wrote:
> > >
> > > > Insure that the max peak of the audio signal is within
> > > > the ADC range.
> > >
> > > Diode clamp it !
> > >
> > > Graham
> >
> > Yeah you can clamp it but then you loose that and higher values as
peaks.
> > The whole idea is to convert the peaks to numbers not to clip them
off.
>
> You can actively diode clamp. Just don't want to hurt the poor ADC 'just
in
> case'. I doubt that for flickering lights, losing anything below say
0x240
will
> hurt any
>
>
> > There's really no need to clamp it. The processor input will have
internal
> > "diodes" that will keep the voltage from exceeding the rail voltage
plus a
> > little.
>
> A discussion we've had many a time before here !
>
>
> > Likewise the input voltage won't go below ground.
>
> It WON'T ? In what ideal world is this ?
>
>
> > A series resistance should be added to limit the input current and a
shunt
> > resistance
> > added to keep the DC level from ****fting up due to rectification by
these
> > clamps.
>
> Uh ?
>
> Graham
Well, if there is an internal diode from the input to the negative rail,
it
will keep the voltage on the input from going below ground, ignoring the
diode drop, of course.
Now, if you capacitively couple to the input, this diode will rectify the
negative going ****tion of the audio signal and charge the capacitor,
positive towards the input. This will offset the zero base line in the
positive direction and screw up the peak detection. A judicious resistance
to ground with an appropriate series resistance will limit the current and
drain off this offsetting charge. It ain't rocket surgery!
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