[sdiy] Issue with CD4024 Ripple Counter

David G Dixon dixon at mail.ubc.ca
Fri Sep 24 01:32:46 CEST 2021


So, today I bought four more CD4024s from my local shop (Lee's Electronic
Components on Fraser St. in Vancouver) -- two CD4024BCN and two CD4024BE --
and I tested them on my breadboard with the CD40106 oscillator.

Results: Same.  BCN work fine, BE clock backwards.

I noticed that the other verbiage on the BEs is the same as the ones I had:

10Y2FKM

This means that they are all from the same batch, and they are obviously all
defective.  I'm going to tell Lee's about it, and I also have a case opened
with TI Customer Support to discuss it.

In other news, I took to heart what someone here said (can't remember who),
and I've redesigned the circuit around a single 311 comparator and a 4013
dual D flip-flop (which I also bought several of today).  This is a simpler
circuit with fewer components (fewer resistors, no diodes), and since the
4013 is clocked on the positive edge, I don't need an inverter -- I'm just
going to divide the comparator output by a factor of two with a couple of
4.99k resistors and send that directly to the Gate Out jack.  I know it's
not buffered, but I'm expecting that it will mostly be plugged into things
with 100k input impedance, so no worries.



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