[sdiy] 4027 flip-flop weirdness

[Philippe Derenne]

A missing decoupling capacitor would be a possible cause as wel...

Phil.

----- Original Message ----- 
From: "Scott Gravenhorst" <music.maker at gte.net>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Monday, March 09, 2009 6:36 PM
Subject: Re: [sdiy] 4027 flip-flop weirdness


> 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
> ________________________________________________________________________
> -- Scott Gravenhorst
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