how to generate pulse 1 second with 555

Discussion in 'The Projects Forum' started by bungfaiz, May 17, 2008.

  1. bungfaiz

    Thread Starter New Member

    May 17, 2008
    3
    0
    i want to make a digital clock....
    how to generate 1 second pulse with 555 ??
    how to calculate the time constant ( R &C) which help 555 to generate pulse? please reply
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    check this website

    http://www.uoguelph.ca/~antoon/gadgets/555/555.html

    or type in google 555 tutorial
     
  3. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    I have my reserves when using a 555 as a timing generator for a clock. With a 555 you can't generate a enough precise signal, even if you use low tolerance resistors and capacitors (below 1%) for your time base.
     
  4. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
    How precise do you need to be?

    Solutions include:

    Divide your line frequency.
    Divide a crystal frequency.
    Buy a GPS receiver with 1 PPS out.
    Buy a Cesium Oscillator.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    cumesoftware is absolutely right. You will be very unhappy with the accuracy of your clock if you try to use a 555 timer.

    There are a couple of 4000 series CMOS ICs that will help you out, depending on what you want to do; run from the power company's 60Hz signal, or do your own crystal-controlled clock.
    The 4040 can be used to get a 1Hz signal from the power company's 60Hz AC.
    The 4060 can be used to generate a 1Hz clock using a crystal. This is what you need for a battery-powered clock, or if you want a backup clock for a line-powered clock.

    You can get datasheets from ON Semiconductor's site; these applications are shown in the datasheets:
    http://onsemi.com
    Part numbers:
    MC14040B
    MC14060B
     
  6. bungfaiz

    Thread Starter New Member

    May 17, 2008
    3
    0
    ok..thanks guys
     
  7. bungfaiz

    Thread Starter New Member

    May 17, 2008
    3
    0
    can u give the pic of 4060 circuit with crystal wookie??
    cause i dont really understand...
    thx a lot
     
  8. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
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