Numbers jump when carry is low on a BCD counter

Discussion in 'The Projects Forum' started by Orbitingful, Jan 30, 2016.

  1. Orbitingful

    Thread Starter Member

    Oct 31, 2015
    I am using two 4510 counters which I want to connect together so I can count from 0-99. I have connected carry of the right BCD to the clock of the left. However when carry is low, and I change the direction of the BCD, the left number jumps. Carry is low when the number is 0 when counting down and 9 when counting up. So if I have a number containing 0, e.g. 60, and I change the direction to count down, the number jumps. How can I stop the numbers jumping when changing the direction at 0 carry?

    Thanks for the help. I can include a schematic.
  2. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    This is a circuit design forum. No schematic = very iffy answers.

  3. dl324

    AAC Fanatic!

    Mar 30, 2015
    Post a schematic and be more precise with your description. The counter has pins for carry out and carry in. Which are you referring to when you say carry?

    Do both digits "jump"? Does jump mean change by one digit (e.g. 0 to 1 or 0 to 9), or do they jump by several numbers?
  4. hp1729

    Well-Known Member

    Nov 23, 2015
    How close is this to what you have?
    It counts up and down with no unexpected behavior.