Logic and counter circuit?

Discussion in 'General Electronics Chat' started by electronice123, Feb 7, 2009.

  1. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
    302
    0
    I am trying to build a circuit to do the following.

    The circuit has a vco which provides a digital input to a counter which counts to 4. Each count turns on a seperate flip flop. I can't figure out how to prevent the counts 1 and 2 from turning on when the counter counts to 3 and turns on the # 3 flip flop.

    http://i51.photobucket.com/albums/f389/xbradkx/1111222.jpg
     
  2. AlexK

    Active Member

    May 23, 2007
    34
    0
    Maybe you can make the following logic before entering #2 flip flop:

    AND(NAND(Q1,Q2),Q2)

    Meaning, if both Q1 and Q2 are high then the input to #2 is always low.
    But, if one of them is low then the input to #2 will be simply Q2 because AND(1,Q2)=Q2.

    Similar logic can be put before #1 flip flop.

    Hope this helps.
     
  3. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
    302
    0
    I tried that, but using those gates a 1 or 2 output from the counter will turn on both 1 and 2 flip flops?

    I know there's a way to do this???
     
  4. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
    302
    0
    I figured it out, using an OR and EX-OR gate! Works Perfectly!!!
     
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