Pete C. wrote:
Ed Pawlowski wrote:

"But wall clocks and those on ovens and coffeemakers - anything that flashes
"12:00" when it loses power - may be just a bit off every second, and that
error can grow with time."

Most anything that "flashes 12:00" is going to be using a crystal
timebase and not care about power line frequency. They flash 12:00 since
when they loose power they need to have the time set again, not anything
to do with line frequency.

Dad built one of these kits in the early 1970s:

http://www.hydroponicsonline.com/sto...0669615117.jpg

Power outage causes it to display 88:88:88, and it's line locked, no
crystal. He said it started to be off by a few seconds a month,
starting a couple of years ago, and he suspects the power company.