Wouter,

Most of the pins on the PIC18F6720 are committed, I can bring out the SPI
and an enable to
talk to say a ADC with SPI interface but it would add quite a bit of cost
and PCB real estate for ADC IC, power supply
and Opto Isolators on the HV side.

The current provisional design is using AN1,AN2,AN3.

Maybe another micro on the HV side could be added to do the conversion but
this also needs a PSU,
ICSP for programming and opto isolators.

What was your idea ?

Thanks

Regards

David


-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
Of Wouter van Ooijen
Sent: Saturday, 30 July 2005 5:21 PM
To: 'Microcontroller discussion list - Public.'
Subject: RE: [OT] Circuit for measuring mains voltage


> I am looking for an isolated method of measuring mains
> voltage (230VAC).
>
> First thoughts are a Opto coupler running in its linear region ?
> My concerns are that the transfer ratio degrades over time.

Do the measuring at the HV side and transfer a digital signal via an
optocoupler.

Wouter van Ooijen

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Van Ooijen Technische Informatica: www.voti.nl
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