MOD-16 Down Counter

Discussion in 'Homework Help' started by wjunfa, Jan 23, 2009.

  1. wjunfa

    Thread Starter New Member

    Jan 23, 2009
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    Guys, how do i contruct a 16-down counter using 7493 IC?
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. Wendy

    Moderator

    Mar 24, 2008
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    SN7493 Datasheet

    Easy. Put invertors after the outputs.

    0000 becomes 1111
    0001 becomes 1110
    0010 becomes 1101
    et cetera.


    I had to work through a similar problem a while back.
     
  4. wjunfa

    Thread Starter New Member

    Jan 23, 2009
    3
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    thanks for the help, it works great by connecting an invertor at the end

    How do i add-on the start/stop and preset inputs such that at any time, the counting could be paused or resumed using the switch or preset to 11111 ?
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Preset in this case is reset. A simple external AND gate will provide the start/stop functions, since that function is only on the 7490.
     
  6. wjunfa

    Thread Starter New Member

    Jan 23, 2009
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    Could you show me how to connect up using the AND gates as start/stop?
    Dont you need a 7474 flip-flop to do it?
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    A simple AND gate would do it. Ever use diode gates?

    [​IMG]
     
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