Digital clock using 74ls160

Discussion in 'The Projects Forum' started by ronald214, Jan 15, 2011.

  1. ronald214

    Thread Starter New Member

    Jan 10, 2011
    4
    0
    Hi.


    I'm working on a digital clock for my project. I'm using 74ls160. I can make the seconds go until 59 and reset to 00, but I don't know where to connect on the next phase. I built the circuit, but when the seconds goes to 00, the minute does not change or does not count. I'm using CircuitMaker to draw the schematic. Please help.


    Thanks,
    Ronald
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You should be aware that most members do not open MS .doc files, as there are too many viruses that tag along. Graphic files in .PNG format are preferred.

    You must be using some external gates to sense a count of 59 and enable the next clock to reset the two counters back to 00 (or do a parallel load). That same condition can be used to make the CET line true on the minutes counter (pin 10). That will let the seconds go to 0 and the minutes count up by one.

    The same works for minutes to hours.

    It helps to have a data sheet for the IC.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Word is definitely not the package you should use to communicate schematics (what beenthere said), so I translated what I could over. I don't know if I got the total image or not, since I use an old version of word, but here is what I saw...

    [​IMG]
     
  4. ronald214

    Thread Starter New Member

    Jan 10, 2011
    4
    0
    Thanks for the help, and yes, I'm using a NAND gate to so reset. I got it to work, but one little problem. The seconds goes 58-59-60-01-02...... Any advise how to elminate count 60 and make 00 on the display.


    Thanks
     
  5. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    So it doesn't have a 00 count after the false 60 count?
     
  6. ronald214

    Thread Starter New Member

    Jan 10, 2011
    4
    0
    @tom66> it doesn't have a count of 00. It goes 60 - 01. As soon as the seconds goes 01, the minutes counts up.
     
  7. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    I would suggest you post your schematic. You want the pulse to be generated on the falling edge of 59 which is fairly easy to do using a few logic gates. I don't know why 00 is skipped though.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You need to use a 3-input NAND, like this:

    [​IMG]

    I'm using the digital simulation mode. In the Student version, analog components (resistors, capacitors, etc) don't simulate in this mode, so I omitted the current limiting resistors to the displays.
     
  9. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    How is that? Your U10 seems to be the units part of the minutes counter, and has no inputs but the clock and reset. The operation will be very erratic with the enable inputs floating.

    You really need to make an accurate schematic.
     
  10. ronald214

    Thread Starter New Member

    Jan 10, 2011
    4
    0
    Finally, after 2 weeks since I started to work on this project. I finished my schematic and I built clock just right now. I think I figured it out. I used 4-input NAND binary 9 on the ones digit and 5 on the tens digit. Now, it counts 58-59-00-01. Feedback and suggestion on the schematic please.


    Thanks.
     
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