As I have no practice with AC voltages, I'm asking if the following circuit is reliable for measuring AC voltages about 110Vca and 220Vca 50Hz/60Hz.
I have already made it with a small transformer. But now, I want a more compact way, because I'm planning to do a board for logic control (like PLC) which inputs detects 110/220 as TRUE. A second application is to measure de AC network level.
I have the foolowing questions about the circuit:
a) Is reliable? If not, a fuse could be a solution to stop the things when it goes wrong? (Consider that I plan to split the ~5M resistor in two, 2.4 or 2.7M).
b) In home the pins are phase, neutral and ground. Need I to connect the phase in C4 and the neutral as my circuit ground (or the ground pin is my ground too)? If yes, what to do in case of inverted connection?
c) What type of capacitor must be used?
Thanks in advance!