[sdiy] 4027 flip-flop weirdness

[Scott Gravenhorst]

Karl Ekdahl <elektrodwarf at yahoo.se> wrote:
>
>Hi list, i have a strange problem; i can't get a 4027 flip-flop 
>to behave like a flip-flop. I've got J & K high, SD & CD low, and 
>i feed CP with a debounced positive-going signal. All i get is a 
>high Q while CP is high, and then a low Q as soon as CP goes low. 
>Am i missing something here? I've tried several ICs with no luck 
>BUT i do have a version i did a week or two ago that works like a 
>charm. I also tried decoupling my power-rails but to no avail... 
>


Are you _100%_ sure that your clock is really debounced?  Is it slewing
fast enough when it changes state?  

What I would do - use a nice square wave oscillator with an output that
conforms to the logic standard to drive your clock input.  Then watch
the Q output with a scope, it should be exactly 1/2 the frequency of
the input clock.  If that works, then the flip flop is toggling and
your debounce needs work.  

-- ScottG
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-- Scott Gravenhorst
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