I remember reading that the frequency at any given time is usually somewhere between 49.9Hz and 50.1Hz (and similarly around 60Hz I'd imagine). So for a 50Hz c

I remember reading that the frequency at any given time is usually somewhere between 49.9Hz and 50.1Hz (and similarly around 60Hz I'd imagine). So for a 50Hz clock, it's not very accurate at all. However, I just found that the _average_ frequency over a length of time should be exactly 50Hz, so it is, in fact, good for keeping time. More here: https://wwwhome.ewi.utwente.nl/~ptdeboer/misc/mains.html https://wwwhome.ewi.utwente.nl/~ptdeboer/misc/mains.html