[sdiy] Issue with CD4024 Ripple Counter

[David G Dixon]

I've used them for years without issue.  This is the first time I've had
problems.  I'm just wondering now whether all of my ASRs were actually
clocking on the wrong edge and I just never noticed it.
 
But, if I can't clock it with a comparator output with a 13V/us slew rate,
then it's just too hard, or else (as I suspect) my chips are faulty.

  _____  

From: bbob [mailto:fluxmonk at gmail.com] 
Sent: Friday, September 17, 2021 12:10 PM
To: David G Dixon
Cc: synth-diy mailing list
Subject: Re: [sdiy] Issue with CD4024 Ripple Counter


[CAUTION: Non-UBC Email]	
lots of designers have used CD4000 series CMOS in SDIY circuits
successfully.  they have their place if used properly, and their limitations
(like every technology).  would be a shame if a newcomer were to be scared
off of perfectly good parts just because you couldn't get it to work in your
application.   

bbob drake

On Fri, Sep 17, 2021 at 2:52 PM David G Dixon via Synth-diy
<synth-diy at synth-diy.org> wrote:


So, I went to the lab and set up a little breadboard.  I put 4024 on it,
used my +15V and 0V rails to power it (yes, I decoupled with 104), and I
also set up a TL072 as a comparator driven by a triangle-wave LFO.  I sent
the output of the comparator through a diode to have it go just between 0V
and +15V.  I tried clocking two CD4024BEs, two CD4024BCNs, and one
MC14024BCP.  The CD4024BCNs didn't even work.  The CD4024BEs gave me some
really hashy looking outputs.  The MC14024BCP worked perfectly.  Then I
tested them in an ASR, with similar results.

So, I threw all of the CD4024s into the trash.  Unfortunately, I only have
one MC14024B.  I'm going to buy more, cuz they work well, without any
issues.

Lesson learned, I guess.  I'm just not sure what the lesson is, other than
"don't use CD4XXX chips" or at least ones with edge-driven inputs.
Argghh!!!  Why can't this stuff just work?  It's a miracle that we aren't
still living in caves, wearing skins and hunting sabre-tooth tigers with
sticks.

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