NavList:

If U.S. electric power companies do fully abandon regulated 60-Hz operation, it will make synchronous timing motors obsolete.  These are less common now than in the past, but they're still widely used in, for example, the timers for driveway post lamps.  A few decades back they were very common in clock radios as well as telescope clock drives.  I have a vintage pair of Haines clocks that plug into household AC and run on timing motors, one displaying solar time and the other sidereal.

American troops during the Vietnam War learned what life was like without carefully regulated 60-Hz current.  Most (if not all) bases had large diesel generators for electricity, and their output frequency was only roughly 60 Hz. A clock set one day could be 10 minutes off the next morning. In fact, the famous “Gooood Moooorrrrrning Vietnam!” on the Armed Forces Radio Service (AFRS) provided a time signal of sorts, telling troops to when to get up or risk missing breakfast or a duty muster. They could leave a radio on all night (when the AFRS was off the air), to be awakened at precisely 6 a.m. by the iconic sign-on.

The real-life broadcaster who started doing this in 1965 was Adrian Cronauer.  His successors on the AFRS continued it as war dragged on, and Robin Williams immortalized it in the 1987 movie of the same name.  (By the way, Cronauer died just last month, at age 79.)

Roger

---------Paul Hirose wrote -------    

Only a few years ago the clock on my microwave oven never needed

adjustment except for daylight saving time changes and the occasional

power failure. That's no longer the case. An article at the NIST site

explains. . . .