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how to generate a 1hz clock

Discussion in 'Electronic Basics' started by Yaron, Oct 14, 2003.

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  1. Yaron

    Yaron Guest

    I just wanted to know how
    can I generate a precise 1 hertz clock pulse.
  2. It all depends upon your definition of precise. You need to state some
    limits like accuracy, cost, size, power requirements etc. If you need
    an extremely "precise" 1hz clock, use a GPS receiver. If "wall clock"
    accuracy is your goal use a crystal based oscillator or maybe hack a
    cheap quartz clock module. If you're cooking eggs, use a RC based
    circuit like 555 timer. ;-)

  3. Don Bruder

    Don Bruder Guest

    Use a 74HCU04, two caps, two resistors, and a known-value crystal.
    (Somebdy please refresh my memory on the name for this type of
    oscillator? I think it starts with "F", but I'm not sure.)

    Feed the output to circuitry that behaves as a "divide by <crystal
    frequency> counter", and take your 1 Hz signal off of the output from
    that. You may want to feed it to a schmidtt trigger to be sure it's nice
    and clean before actually putting it to work, but I'd consider that an
    optional improvement. Presto. Crystal accurate 1 Hz oscillator :)

  4. You can use a 32.768 kHz crystal oscillator, and then divide that frequency
    using a 15-bit binary counter. The crystal's frequency value is a power of
    2, so the division will be perfect and you'll end up with an accurate and
    precise 1 Hz square wave. The crystal is cheap and easy to find, as it is
    commonly used in digital watches.

    Or, you could use a small microcontroller (with a crystal oscillator) and
    generate the pulse with code. This could well be the easiest solution (only
    one IC required), depending on how familiar you are with MCUs.

    Check this link for more info:


  5. John Larkin

    John Larkin Guest

    Buy a cheap mechanical-dial quartz clock and tap into the stepper
    motor drive pulses.

  6. Bill Bowden

    Bill Bowden Guest

    There is digital clock circuit with a 1 Hz generator at :

    It uses a 32768 Hz watch crystal and a 4020, 14 stage counter
    to get 2 Hz. The 2 hertz signal is divided by 2 to get a
    1 Hz square wave out of the 4013 flip flop.

    There is also another clock circuit that divides the 60 Hz line
    frequency down to 1 Hz. but you need almost as many parts either

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