self stater for JK flipflop UP/down counter

Discussion in 'Homework Help' started by flonchon, Oct 17, 2015.

  1. flonchon

    Thread Starter New Member

    Oct 8, 2015
    5
    0
    Hello :), I have a JK UP/DOWN counter project to build.
    my sequence is 1, 3, 5, 7, 12, 13, the count should start with 000 but after finish one cycle (from 1 to 13 for UP counting) the number 0 doesn't have to display anymore.
    I did my karnaugh map, drawing and building. I self start at the number 1 to check if my sequence work, my DOWN counting work, and my UP counting also but I don't get it how to self start at 000. I did connect all my clear to my self starter but It doesn't work. Thank you...
    20151015_231218.jpg 20151015_231255.jpg 20151015_231309.jpg
     
  2. RBR1317

    Active Member

    Nov 13, 2010
    232
    48
    What is the part number of your JK FF?

    Is it TTL, LSTTL, CMOS?
     
  3. flonchon

    Thread Starter New Member

    Oct 8, 2015
    5
    0
    my flip flop number is 74ls76 TTL
     
  4. flonchon

    Thread Starter New Member

    Oct 8, 2015
    5
    0
    it's alright I got it, I had to connect all my clear to my self start, and my preset to VCC.
     
  5. RBR1317

    Active Member

    Nov 13, 2010
    232
    48
    Assuming that the RC circuit at the far right is the self-starter, how do you ensure that the 10 uF capacitor is fully discharged for startup? Does it completely discharge through the +Vcc terminal?
     
  6. flonchon

    Thread Starter New Member

    Oct 8, 2015
    5
    0
    yes the RC circuit is the self starter, our tutor told us to connect a 10 Kohms resistor and a 10 uF capacitor for our last project (up counting).
    I didn't think about that thank you, is it mean I need a bigger capacitor value to completely discharge through the +Vcc terminal?
     
  7. flonchon

    Thread Starter New Member

    Oct 8, 2015
    5
    0
    I just tried with 10 uF it works up and down counting when I self start with any of my sequence number (1, or 3 or 5...etc).
    Only when I self start at 0 (all preset to VCC and all clear to RC circuit), I have a problem with my down counting, it starts at 0 but after instead of have one of my down digit number, nothing display on my 7-segment and all my LED are ON, only after that it count normally.
     
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