[sdiy] Issue with CD4024 Ripple Counter

Magnus Danielson magnus at rubidium.se
Sat Sep 18 17:59:30 CEST 2021


Hi Dave,

It sounds like you have ground-bounce problems. This comes from 
parasitic impedance, and primarily in power-lines. First level fix is to 
put ceramic caps across the power of each chip, and real close to keep 
the loop small. Larger loop = larger parasitic inductance = larger 
ground-bounce. Also consider how signal is routed and that there is a 
good return-path for the mirror current as you feed it from one chip to 
another. For classic CMOS this should not be too difficult, but it's the 
same thing that shows up.

Cheers,
Magnus

On 2021-09-17 05:57, David G Dixon via Synth-diy wrote:
> Hey SDIY Team,
> I've got a device that uses a 4024 ripple counter.  The datasheet says 
> that it advances on the negative transition of the clock.  All mine 
> (CD4024BE) are advancing on the positive transition of the clock.  
> However, I tried an MC14024BCP and it worked properly.
> Am I smoking crack?  Why are my CD4024s behaving opposite to the 
> datasheet, but the MC14024 is behaving as per the datasheet?  What is 
> it that I don't know about these devices?
> Cheers,
> Dave Dixon
>
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