hello raghu!

clarifications: I need only voltage (VAC, since I want to measure the power outlets of my home)

what I did: a rectified the output (9 VAC) of a small transformer with a rectifier bridge and to smooth the ripple I added a 220uF electrolictic capacitor.

My circuit reads the output, do the calculations and show the maximum, minimum, average voltages (right now max=122V, min=113V, average=117V, it has been running for a few hours)

why I am doing this? mostly for fun and a pratical purpose: electricity bills in Brazil have some quality indicators that the power company must follow, as demanded by ANEEL, the government's regulatory agency), there are 3 indicators related to power outage in a 30 days period , DIC (maximum 13h without power), FIC (up to 8 times without power) and DMIC (maximum of 11 continous hours without power)

these values are printed in the bill, but how do you know? Is the company that tells these values to you, so I'll see if they are sincere :-)

I looked the IC that you said, but I think it's not what I need... what I really needed was some kind of OP-AMP that I could connect directly to the mains AC and could read a low voltage DC output proportinal to the AC input.

I read something about one OP-AMP from analog devices that could withstand up to 500VAC in its inputs, but I don't remember if it was a peak value or if it is a operational value.

thanks for the advice.

orlando