Why can't you use a transformer. Are you measuring just voltage or
voltage and current. If you need to make unisolated measurements you can
float the PIC on the mains BUT the output MUST BE ISOLATED...

Check out Burr-Brown app notes on instrumentation amps. They have some
good app-note examples on AC line measurements and precautions that must
be taken into consideration.

Carlos Maidana wrote:
>
> Hi All:
>
>         I need made measures in a 220 VAC line with the a/d converter of
> PIC16C71. I can't use transformer.The range of scale starts in 170 VAC and
> ends in 250 VAC. Does anyone knows if exists an aplication note about the
> analog pre-processing VAC signal.
>
> Thanks.
> Carlos Eduardo Maidana
> Departamento de Desarrollo
> Magna Scientific S.A.

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