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There are multiple hardware solutions to do amp/current monitoring, but I cant seem to find one to do AC Frequency monitoring. Anyone have a pointer to board that can handle line power and return line frequency?

I have devices that are sensitive to Dirty power, and when the frequency of the line strays too much from 60 hertz I want to flip-a-switch…

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    This might be considered off-topic. Consider using a search engine to get some information on power line frequency meters from the Internet. If you elect a "DIY" approach, keep in mind that accurate frequency measurement will require an accurate time source. Also know that RPi's timekeeping is not considered particularly accurate. Finally, more info on RPi timekeeping can be found here
    – Seamus
    Jan 3, 2020 at 22:16
  • Electric power distribution (at least in advanced countries) rigidly controls the power line frequency. While there may be minor variations the average frequency is maintained to a high level of accuracy - at least an order of magnitude better than the Pi clock!
    – Milliways
    Jan 3, 2020 at 22:38
  • Hi@Stuart Siegler，Welcome and nice to meet you. Ah, let me see. My home 220V 50Hz mains was once very dirty. I used a scope to look at it, but home MCB blew up immediately. I googled and learned that it is the scope grounding problem. So I used a hand held scope and saw how dirty, with ugly glitches, was the AC wave. Later I used a very low power transformer to step down 220V AC to 3/6/12V (AC is now floating, so I can use desktop scope to look at it). Then I rectify AC to DC. Now I have a positive going only sine signal to mess around. / to continue, ...
    – tlfong01
    Jan 4, 2020 at 2:23
  • I use a HCT14 Schmitt inverter assets.nexperia.com/documents/data-sheet/74HC_HCT14.pdf to convert the sine signal to digital signal to read and count by Rpi GPIO. Now it is all Rpi python's job to data log, do analysis and make an AC frequency deviation statistics report and complain to the power company (Yes, I did that). PS - I also DIYed a frequency counter using 32.768Hz quartz clock module, binary and decimal counter, 7 segment LEDs. But the all 74HC hardware DIY frequency counter is only for human eyes only, /to continue, ...
    – tlfong01
    Jan 4, 2020 at 2:24
  • I later found that using minimal hardware (in this case only HC14) and let all the rest for Rpi to do is the most time and space saving effective and efficient, way to do AC power line monitoring. By the way, my city's power company is now introducing home use "smart" electricity meters. I am anxiously waiting to get one and hack inside for AC power frequency and amplitude data etc. Cheers.
    – tlfong01
    Jan 4, 2020 at 2:34

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