Digital Alarm Clock

Discussion in 'Homework Help' started by msak671@hotmail.com, Oct 27, 2013.

  1. msak671@hotmail.com

    Thread Starter New Member

    Aug 4, 2013
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    I am making Digital alarm clock, i have uploaded circuit diagram of digital clock, i want to ask that how can i make it alarm clock?
    which IC should I use?
    Please Help me out.. :)
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    That is a lot of work and chips to make an alarm clock. The only reason one would design a clock in this manner is to learn how digital counter circuits work.

    You can make a digital alarm clock with one mcu chip.
     
  3. msak671@hotmail.com

    Thread Starter New Member

    Aug 4, 2013
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    This is my project of Digital logic Design,
    so i can not use any type of micro controller.
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    So this is homework project. Adding an alarm feature would be extremely complicated.

    You could limit the alarm to trigger on the hour only.
     
  5. bertus

    Administrator

    Apr 5, 2008
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  6. JohnInTX

    Moderator

    Jun 26, 2012
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    You could use 74LS85 magnitude comparators that compare the BCD hours and minutes to values set on thumbwheel BCD switches to hold the alarm time. A=B is the alarm output.

    The alarm time could also be the outputs of 4 more 7490's (or some BCD up/down counter) that uses buttons to count to the desired alarm time in the same manner that you set the time of day. In that case, you would need to multiplex the digit values between the alarm and time registers so that you could see the alarm setting.
     
  7. WBahn

    Moderator

    Mar 31, 2012
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    The brute force way would be to take two of these clocks and disable the clock signal for one of them (assuming that you can still set the time without it, which I can't tell because I can't read the schematic details well enough). Then use a quad XOR gate for each digit (or perhaps just the hourse and minutes) to compare the values on the two clocks. Combine all of the digits with NOR and you have a signal that goes HI only when the output of the two circuits match. Use that for your alarm trigger.
     
  8. jocc

    New Member

    Jan 28, 2014
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    hey man, have u gotten solution for ur digital alarm clock design? if so please help me by attaching it. coz u know i'm on agreat confusion on it and i need a help of espeasially yours. and make it fast
    THANK YOU
     
  9. MrChips

    Moderator

    Oct 2, 2009
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    Watch your language and tone of voice.

    The purpose of AAC is to help each other learn and not to serve you on a silver platter pronto.

    Also when someone chooses to type using single letters, poor spelling and punctuation it tells us a lot about his/her personality
     
  10. WBahn

    Moderator

    Mar 31, 2012
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    In other words, "Yo Dude, I want to copy your homework. Give it to me now!"
     
  11. takao21203

    Distinguished Member

    Apr 28, 2012
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    schematics with many wires
     
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