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Electrical Engineering Question: MOD 4 Ripple Counter

  1. Nov 14, 2006 #1
    Hi, I have to design a MOD 4 ripple UP counter that counts in the sequence 10-11-12-13-10-11-12-13-etc... I believe it is right, although it would be nice if you can check. I won't be able to go to the lab until a few weeks.

    You can view the schematic here: http://bingweb.binghamton.edu/~ppandey1/untitled.bmp [Broken]

    And also,

    I have another question:

    The question pretty much says:

    You have a 5 bit counter. The frequency at the output terminals is what fraction of the input clock frequency?

    a: 2^0 ... my answer is 1/2 the original clock freq
    b: 2^1 ... my answer is 1/4 the original clock freq
    c: 2^2 ... my answer is 1/8 the original clock freq
    d: 2^3 ... my answer is 1/16 the original clock freq
    e: 2^4 ... my answer is 1/32 the original clock freq

    I'm assuming they are using a JK flip flop, and I'm pretty sure that the frequency (Q) of each flipflop after the first is halved each time and it continues throughout. Although, they don't say it's a JK. But I'm assuming you use a JK.

    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Nov 15, 2006 #2


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    Staff: Mentor

    -1- Can't you just use a 2-bit counter counting 0-1-2-3 and use logic to generate the output 0xA-B-C-D? And shouldn't you have a reset line to initialize your counter?

    -2- Yes, each output bit in the counter will be a divide-by-2 of its input frequency.
  4. Nov 15, 2006 #3
    (For Question #1) I see what you're saying. I'm not sure how I would implement a reset to initialize my counter. That's a good point, I didn't see that.
  5. Nov 18, 2006 #4
    This is my updated counter:

    http://img228.imageshack.us/img228/8076/untitledbx9.png [Broken]

    I added a manual preset. Look good?
    Last edited by a moderator: May 2, 2017
  6. Nov 18, 2006 #5


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    Staff: Mentor

    Sorry, what exactly is the count sequence supposed to be? Also, you meant to hook up the FF reset for bit 3 to a 1, correct?
  7. Nov 19, 2006 #6
    10, 11, 12, 13... back to 10, 11, 12, 13.... etc

    Yes, sorry that got cut out of the picture.
  8. Nov 19, 2006 #7


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    Staff: Mentor

    Sorry to make extra work for you, but it would be easier for me to check your work if you showed the state transition table. Can you please summarize what all of the inputs and outputs are supposed to do as the counter counts 0xA...0xF,0xA...0xF,..... ?
  9. Nov 30, 2006 #8
    Hey, I figured it out. I verified it with my professor, it's good.
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