Hello ,
Is it possible to convert 0-22V RMS to 0-4.5V DC for arduino ?

 

hi N,
It is possible to configure an OPA to do this, what OPA's do you have on the bench.?
E

 

You could look at an active rectifier, like...

https://www.radiolocman.com/shem/schematics.html?di=56324
Then adjust the gain or have an input attenuator to set the output level.

 

Here is a simple circuit that measures the peak voltage. Because we know rms to peak ratio we can do the math.
Here 22Vrms = 30Vpk. The resistors divide the 30V to just under 5V for the Arduino.

Do you want a real accurate "RMS" reading? or just a mildly accurate "what is the voltage"?

 

?? . . . https://www.google.com/search?q=true+rms+to+voltage+2MHz+bandwidth