In the first version I had that with the switch, after I found that good gate I connected also my photo interrupter to the
74LS14 good gate and made the measurements...
I know it is hard to remote troubleshooting...
I was thinking also about the LM339 to use, but I found more simple to use a 74LS14 in my circuit than the LM339.
I tested in my circuit that one IC 74LS14 which have a good gate and it is doing the job well.
I also connected it to my uC and started to count the triggered signals and works great.
I don't know, maybe I will give a try to another IC but now from the 74HCT version and something not from the year '85.
I just was wondering about my situation with this IC's because I was playing before also whit such of IC's and I never had a burnt one
or situations like now, except if I repaired some electronics with a bad Schmitt trigger...
So, back to the situation, I assume more or less my schematic shouldn't kill the IC's.
Maybe that version where I connected the LED to the IC.
But I have also a bad IC on which was the LED not connected.
I will try to get a new ic but now one from the 74HCT version and make a new test..
I don't know, maybe I messed up something.
Just one more question:
If I don't connect the unused pins to gnd, can that kill the IC?