hi i'm measuring the main voltage and i'm using a micro internal adc for input signal ! i want to use this circuit to scale down the main voltage with transformer from 312(vmax) to 31.2 and then using the op-amp to scaling down and shifting the ac voltage to move the negative part of signal to positive side and make it suitable for adc. is this circuit ok? is there better options? or other circuits better than this one? i simulated it in mathlab and it is working properly. any suggestion would be appreciated...

 

the voltage source1 is 2.5v dc

 

What aspect of the AC voltage are you trying to measure? Peak, Average, RMS, frequency, zero-crossing? Each requires a different technique, adc sampling rates, etc...

 

all of them...
tnx for your reply
i'm going to measure the current too and then calculate the power,pf,frequency and ...
my adc is 12bit , 30Ms/s. i guess its about programming to calculate this values . is this circuit going to limit me to calculate them?how?

 

hi i've changed my circuit to this to get rid of op-amp ...
how aboat this one?
should i consider any thing here??

 

What are the functions of Resistor3 and Capacitor? The transformer output is a floating voltage source, and does not need an explicit ground reference to function in this circuit. It stacks on top of main voltage 1 just like two batteries in series.

ak

 

Just FYI, there are lots of chips available that already do what you want, and more.