In article ,
newshound writes:
For reasons I won't bore you with, I'm interested in building a cheap,
simple data logger to monitor mains voltage, ideally two channels (live
to earth and neutral to earth). In the dim and distant past I have
designed and built such things more or less from scratch, but surely
someone has already done this.

I havn't used either Arduino or Pi before, but I assume one or other
would be the obvious starting point.

However ATM google isn't giving me a strong lead. Thoughts?

Funny, I've just built some hardware to do this on a Pi
for a presentation and demo I'm doing later this month.
However, the object was to demonstrate using an ADC on a
Pi rather than specifically to measure the mains voltage,
although I thought it might be fun to record mains voltage.

As has been said, the Pi doesn't have native ADC built-in,
so you would need to add on ADC's.
However, another significant factors would be which of these
platforms you have familiarity with, and if having a linux
OS there would be useful for the project, or not.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]