Wouldn't it be simple to scale, isolate, then sample the AC wave as many
times as is practical, then use the highest reading to get the peak, then
*.707 for RMS.....
Sound like this is what you have in the works.

Or, how about rectifying the output of a CT and putting it across a known
resistance then figuring the equivalent RMS value...It would probably be
easier to work out table values for this one, but it would be safest all
around.


Chris

> Hi,
>
> I want to use a pic to measure AC line voltage. First, my
> hardware scales
> down 200V to 5V and flips the negative duty cycle to positive
> so that the
> pic can read the signal. Then the pic reads the voltage every
> 0.1ms with an
> adc port. Now I have many almost 100 reads within a duty
> cycle. No this is a
> math question: How do I calculate the AC voltage from these reads?
>
> Thanks,
> Tony
>
>

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