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Digital clock 101 question

Discussion in 'Misc Electronics' started by dakota7, Aug 15, 2003.

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  1. dakota7

    dakota7 Guest

    I am a fiend about clock accuracy - my computers synch up with a time
    server on startup, and all the clocks in our house are synchronized to
    the second. And I notice almost immediately when any of this changes.

    Last night, I was awake in bed and noticed that the clock by my bed said
    4:28 when a downstairs windup clock was bonging 4:30. The windup clock
    isn't perfectly accurate, but when it slips by a minute, typically once
    a month, I just reset it and it's acceptable for another 30 days.

    When I woke up this morning, I noticed an interesting phenomenon: EVERY
    electric digital clock in the house (five in all, not counting VCR) was
    two minutes slow.

    So my question: Could this somehow be related to the northeastern US
    power failure? Our house didn't lose power. But if the local utility
    was somehow "cycling down" its output as a conservation technique - I
    have no idea if such a thing is possible of course - could THAT have
    caused my clocks to all lose two minutes?

    No other scenario is possible:

    - Virtually every night, I notice if the bedside clock matches the
    windup clock. It did Wednesday night; it didn't Thursday.
    - No one else in the house reset the clocks.
    - The oldest digital clock has no battery or memory - cut power to it
    for a nanosecond, and it resets to 12:00 and starts flashing.
    - My watch, the computer clocks, the windup clock, and the two
    battery-powered clocks in the house, along with the clocks in our cars,
    all had the same (correct) time, two minutes ahead of the one shown on
    the digital clocks.
  2. JeffM

    JeffM Guest

    ...this morning...EVERY electric digital clock...was...two minutes slow.
    Imagine putting your finger into a running fan.
    If you don't insert and remove it at exactly the right moment,
    bad things happen.

    Similarly, power generators on the electric grid of the US & Canada
    have to be synced EXACTLY or bad things happen.

    My sense of it is, you DID lose power.

    When clocks switch over
    from the precise 60Hz power line as a timebase
    to internal (usually cheap) oscillators,
    they generally gain or lose time.
  3. CWatters

    CWatters Guest

    Most likely the chimes on the wind up just went off early? Did you check
    against an outside source?

    Who was it who said "A man with a watch knows the exact time, but a man with
    two watches is never quite sure"
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