1 pulse per second clock

Discussion in 'The Projects Forum' started by engwas, Nov 19, 2009.

  1. engwas

    Thread Starter Member

    Jan 9, 2009
    18
    0
    Hello
    I want to bulid a digital clock and I need to generate clock (1pulse/1sec) and this clock must be accuracy so i need a circuit to generate it
    note that 555 not accuracy to generate 1 pulse /sec

    Thankls
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Is it powered by 50Hz AC, 60Hz AC, or batteries?

    For the latter, look at a CMOS 4060 IC; a 14-stage binary counter/oscillator.

    For the former, look at a CMOS 4040 IC, a 12-bit binary counter.
     
  3. engwas

    Thread Starter Member

    Jan 9, 2009
    18
    0
    It's powered by battery
    So i need you circuit to generate this clock
    if i use 4040 or 4060 that mean no need to give them a clock or i must connect a clock to them ?
    I appreciate if some on gave mr the circiut
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You will need to download a datasheet for the IC.
    Some part numbers:
    CD4060B - Texas Instruments, National Semiconductor, many others
    MC14060B - Motorola/ONsemi
    HEF4060B - Phillips/NXP Semiconductors
    They are all the same, made by different manufacturers.
    Find datasheets from several manufacturers, and look at the applications section.
    You will need to use a crystal.
     
  5. engwas

    Thread Starter Member

    Jan 9, 2009
    18
    0
    Dear SgtWooki
    Thanks for answer me,
    So if i use one of them which circuit equipement needed to get the 1 sec clock
     
  6. aboamal

    Member

    May 29, 2008
    14
    0
    This is a related subject about this timer its useful for you


    4060B Timer

    A schematic of the 4060B chip is provided below:


    [​IMG]

    The pins labelled in red Q4-Q14 are the binary outputs: Q4 for the 16's, Q5 for the 32's, Q6 for the 64's and so on up to Q13 for the 8192's, and Q14 for the 16384's.

    Just three external components are required to control the 4060B counter - two resistors and one capactor. The frequency of the internal oscillator (i.e. the speed of the count) is set according to the equation given at the bottom of the schematic below:


    [​IMG]

    Since Q14 represents the 16,384's and Q4 represents the 16's - we know it will take 1,024 times longer (16,384 / 16) for Q14 to flip from 0 to 1 than it takes Q4. So, for an example 2-hour timer (=7,200 seconds), we just need to fine-tune the circuit so that Q4 turns on after 7,200 / 1,024 seconds = 7.03 seconds, knowing that if that is done correctly, after exactly 2 hours Q14 will flip from 0 to 1.

    Putting Together the Timer Circuit

    [​IMG]

    The circuit shown above (from Ron J's Circuit Page) is a timer which energises a relay after a preset time has elapsed. It can be set to time an interval from 30 seconds to 24 hours.

    The orange arrow labelled Range should be connected to a pin on the 4060B chip selected from the RANGE table. If for example, you require a timer to time 3 hours, connect it to pin number 1 on the chip since that pin corresponds to the time range 2hrs to 4hrs.

    3 hours is 10,800 seconds, and we are using the output from pin 1 to trigger the relay. Looking at the SETUP table entry for pin 1 we see that we divide our target time (10,800 seconds) by 256 to obtain the on/off time for the yellow LED at pin 7 = 42.28 seconds. Therefore, if we adjust the potentiometer R4 so that the yellow LED turns on after approximately 42 seconds, we'll know that the relay will be energised after approximately 3 hours.


    [​IMG]

    The diode D1 makes this a one-shot timer. This means that after the programmed time delay of 3 hours, the relay will stay on until the circuit is reset. If the diode is omitted from the circuit then you get a repeating timer with the relay off for 3 hours, on for 3 hours, off for 3 hours, and so on until the circuit it reset.


     
  7. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    If your digital clock is going to use a uC ( mine would ) then it can generate the pulse from its crystal.
     
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,576
    231
    Gut a 1.5V battery wall or desk clock. The two coil outputs are 2-second interval pulses, 180° out of phase that are OR'ed for 1 second pulses. Very accurate! Some are on small PCBs. This one was on a metal frame that was cut down.

    Ken
     
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