getting 1 hz pulse of a wall clock movement

Discussion in 'The Projects Forum' started by Ronald Arjune, May 16, 2016.

  1. Ronald Arjune

    Thread Starter New Member

    Apr 28, 2016
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    Can I get the 1 hz pulse out of a wall clock movement to time a digital clock?
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Should be able to tap off the solenoid pulse if its a battery powered one.
     
  3. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    That depends on how the wall clock is made.
    Many use a 32768 Hz crystal.
    Find the signal, amplify it and divide it by 32768 and you will have your 1 Hz timebase.

    Bertus
     
  4. Art

    Distinguished Member

    Sep 10, 2007
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    You can count a 16 bit word with it starting from 0x8000, and when it overflows, that’s your 1 Hz interrupt.
     
  5. Sensacell

    Well-Known Member

    Jun 19, 2012
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    If your clock is AC powered, divide the line frequency by 50 / 60 and you got it.

    The long term accuracy will be better than any crystal oscillator.
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    If you are talking about the type pictured below and usually available on a clock available from Goodwill or Savers stores as used for $1 to $3, absolutely!

    Accuracy may be off 1 or 2 seconds per day but pretty darn good for most applications. Nice strong pulse every second to power the solenoid (usually a gold-tone silicon-steel plate with an eyelet to rachet the gears of the clock mechanism. You can just tap into the non-grounded lead of the solenoid's coil and connect our circuit's ground to the clock ground. It is likely easiest to keep the clock's battery on the clock instead of using system power for the clock.

    [​IMG]
     
    Last edited: May 16, 2016
    atferrari likes this.
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Per GopherT's suggestion, I've used gutted 1.5V battery clocks for 1Hz clocking. Some wall/desk clock use pullup on the coil outputs. Some use pulldown. Attached are two configurations I've used.

    Ken

    1 Second Clock.gif 1 Sec Clock.jpg
     
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