if you want to sync to mains.. this is what "mains" looks like

Author	Message
TassyJim Guru Joined: 07/08/2011 Location: Australia Posts: 6388	Posted: 07:30pm 03 Dec 2024       The mains supply never claims to be exactly 50Hz, It averages 50Hz so a mains derived clock will maintain time within a few seconds indefinitely. From the aemc standards:   Quote   No contingency event or load event 49.75 to 50.25 Hz, 49.85 to 50.15 Hz - 99% of the time https://www.aemc.gov.au/sites/default/files/content/c2716a96-e099-441d-9e46-8ac05d36f5a7/REL0065-The-Frequency-Operating-Standard-stage-one-final-for-publi.pdf 30 years ago, we used to deliberately get the time a few seconds fast in the morning before the peak so that as load increased, the time gradually came back to correct. As long as we were within 2-3 seconds, everyone was happy. Generators used mechanical governors and the time standard was a pendulum clock adjusted regularly using the time beeps of the radio. At that stage, Tasmania's installed capacity was around 1 GW Jim Edited 2024-12-04 05:34 by TassyJim