AC Voltage sensing


Joined Apr 20, 2004

Your ADC will not like to get plugged into the mains directly. It will not handle that much voltage. So you will need to use a step down transformer to reduce the mains voltage and to safely isolate the measuring circuit. Select one that has an output less than the maximum voltage your ADC will accept.

After that, what you do depends on how accurately you wish to monitor the voltage. If you convert at a high frequency, your data will follow the sine curve of the line voltage. You will be able to see small disturbances, although you will accumulate a lot of data in just a few minutes.

If you just need to follow the trend over time, consider rectifying the voltage to DC, and sample that every few seconds. The data will show you if the mains varies during the day as electrical loads changes with human activity.


Joined Jan 6, 2004
In addition to what Beenthere says, you should tell what do you actually want to measure from your AC voltage: peak, frequency, rms or...?

Just in case you are not aware, dealing with mains requires from you to know the risks involved.

If not, better refrain yourself of doing anything unless you have the assistance of an experienced person. It's just a friendly advice.