it's never over ... done . . . there's always a way to improve things however when something works without issues the next move needs to be studied and compared it's benefits weaknesses against the old one (not just blindly swapped to because it's new and looks better /!\ )

you should study the https://www.google.com/search?q=architecture+design+digital+computing+systems+principles+guidelines while you can

apx. level of detail

 

it's never over ... done . . . there's always a way to improve things however when something works without issues the next move needs to be studied and compared it's benefits weaknesses against the old one (not just blindly swapped to because it's new and looks better /!\ )

you should study the https://www.google.com/search?q=architecture+design+digital+computing+systems+principles+guidelines while you can

apx. level of detail

Thank you.
I will read this video.

 

I add schmitt trigger buffer before the pin6 of U2.
It work normally.
Thanks for everyone help.

best regards

Hi Body :

Thanks for your help to make a long press push button circuit before.
I use a schmitt trigger logic and CD4013 to make a log press push button circuit .
If I want to use a schmitt input D flip-flop.
I found there is a nonstable state on other D flip-flop 74HCS72,74HCS74
These two parts are the schmitt input D flip-flop.
The function table is as follows.


The CD4013 does not have this nonstable state.

This is the reason why we use CD4013 to realize the long push button circuit ?
I can not use one schmitt trigger input D flip flop 74HCS72 or 74HCS74 to replace schmitt buffer 74LVC1G17+CD4013?

 

Note: timer runs as long as button is pressed making the LED go on/off after every timeout period.
Adjust the timeout by R1 and C1