Weird flip flop trigger behaviour?

Discussion in 'General Electronics Chat' started by robijnix, Mar 8, 2013.

  1. robijnix

    Thread Starter New Member

    Feb 23, 2013
    7
    0
    Hello,

    I recently got some pos edge 8 bit flip flops, so i decided to test them by connecting the flip flop to an adder and see what happens:
    http://www.youtube.com/watch?v=TxZwYjTYRE4
    I would have expected the value to increase by 1 every time i make the clock high (that's what i do with that wire in my hand), but as you can see, it sometimes increases by more than 1.

    now i wonder why this is. I thought i might be because when putting the clock wire into the hole i might be making a few very short contacts with the hole before i keep it steady, and it trigger on each of those contacts?
     
  2. JDT

    Well-Known Member

    Feb 12, 2009
    658
    85
    Exactly!

    You need a simple circuit like this using a change-over switch to remove the contact bounce.
     
    robijnix likes this.
  3. tubeguy

    Well-Known Member

    Nov 3, 2012
    1,157
    197
    Yes, I think you're right.
    A bit on de-bouncing switches:
    http://www.elexp.com/t_bounc.htm
     
  4. robijnix

    Thread Starter New Member

    Feb 23, 2013
    7
    0
    Thanks, thats actually a pretty nice solution.
     
  5. sheldons

    Active Member

    Oct 26, 2011
    616
    101
    orrrr there is this one......the section built around a 4093 is the switch debounce section that will work for you
     
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