> Does your phase plot mean that a mains powered wall clock might be off > by 10 seconds? > > Have Fun, > > Brooke Clarke, N6GCE
Yes. I also keep an old AC synchronous motor wall clock around just to see this effect. To be fair, it is unusual for it to be off this much, or for very long. > Maybe we all should run a power line test at the same time and we should > be able to see who is leading and lagging ! > > Brian N4FMN You know, if the stackable TAPR module project catches on another PCB on the list could be a mains frequency monitor. It would robustly filter and divide the 50/60 Hz mains frequency to 1 PPS and then onboard compare that 1 PPS against the local (OCXO, atomic, or GPS) 1 PPS to a modest precision (say, 1 or 10 us). This would be a cheap board and then many of us could monitor mains phase and log it in a standard format. With the right software you could get plots like this in real-time: 60 Hz AC Mains Frequency Accuracy Measurement http://www.leapsecond.com/pages/mains/ For extra credit we could follow the GPScon Z3801A web plot model. See: International Web Plots http://www.realhamradio.com/GPS_websites_list.htm Also, while we're on the subject of monitoring mains frequency do see Bryan Mumford's page. Measuring the accuracy of 60 cycle power http://www.bmumford.com/clocks/60cycle/index.html If any of you also have an interest in precision pendulum clocks and don't already have one of his timers you should look into it: MicroSet Precision Clock and Watch Timer http://www.bmumford.com/microset.html /tvb http://www.LeapSecond.com _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
