[sdiy] Issue with CD4024 Ripple Counter

Sat Sep 18 06:08:09 CEST 2021

Well, I wasn't writing off all CD4XXX chips.  Just the ones with
edge-sensitive clocks.  The ones that just respond to logic levels never go
wrong.

The thing is, I'm developing a product for sale -- another one of my Sketchy
Labs modules -- so it's important that I can rely on the chips I ultimately
choose.  At this point, I would never sell a module with a CD4024 in it.

Also, just to be clear, I had four CD4024s, but they were from two very
different batches.  They had different looks.  Two had a gold stripe on one
end, and the others just had plain white lettering.  All seemed bad.

  _____  

From: Pete Hartman [mailto:pete.hartman at gmail.com] 
Sent: Friday, September 17, 2021 3:28 PM
To: David G Dixon
Subject: Re: [sdiy] Issue with CD4024 Ripple Counter

[CAUTION: Non-UBC Email]	
he wasn't saying you were a noob. :)

He's saying writing off the entire CD4XXX series of chips (with prejudice)
because it sounds like you got a bad batch is going to be alarming to those
around here who are noobs.

I do think fishing a couple out to send to someone to grind down and check
would be an interesting exercise.

On Fri, Sep 17, 2021 at 3:28 PM David G Dixon via Synth-diy
<synth-diy at synth-diy.org> wrote:

I'm tempted to dig those shitty chips out of the trash and mail them to you,
to see if you fare any better, given that I'm such a noob (with 13 years of
experience designing millions of dollars worth of successful synth modules).

  _____  

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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