Yep, I didn’t notice that. But why wouldn’t a Schmitt-trigger XOR gate be all that is required? An SN74HCS86 for example?

Yes, that should also work.
I wasn't aware of that device, which is fine as long as operating with a 2V-6V supply is okay.

 

I'm trying the solution with a XOR and a NAND i'm getting strange results which I'm not sure how to explain. But I have to ask first: am I supposed to put a pulldown res on each inputs? Even if the input is directly connected to the output of another 74xx ?

Also, is it normal that I see 4.5v comming of a NOT if connected directly to a 5v (I'm actually reading 5.08) source? I understand that I would get a small drop but that looks like a lot.

 

I finally got it. I used a combination of some comments in the thread and adapted it to the parts I currently have on hands. It works exactly as I want it so that's a win.

I've attached a drawing of the design. Thanks for all the help everyone. This thread was, by far, the best help I ever got on the internet

 

why wouldn’t a Schmitt-trigger XOR gate be all that is required? An SN74HCS86 for example?

It is all that is required. But NOTE, the HCS part is not a standard 74xx86. TTL and "normal" CMOS XOR parts do not have Schmitt trigger inputs. The part you mention is a special automotive variant with Schmitt inputs.

ak

 

I'm trying the solution with a XOR and a NAND i'm getting strange results which I'm not sure how to explain. But I have to ask first: am I supposed to put a pulldown res on each inputs? Even if the input is directly connected to the output of another 74xx ?

Also, is it normal that I see 4.5v comming of a NOT if connected directly to a 5v (I'm actually reading 5.08) source? I understand that I would get a small drop but that looks like a lot.

You’ll only need

It is all that is required. But NOTE, the HCS part is not a standard 74xx86. TTL and "normal" CMOS XOR parts do not have Schmitt trigger inputs. The part you mention is a special automotive variant with Schmitt inputs.

ak

Yes, I understand that. But, it IS an XOR gate and HAS Schmitt trigger Inputs. The fact that it is an automotive specialty part is irrelevant AFAIK.

 

Agree. I was pointing it out for newbies who might not be familiar with all of the various logic family types, their designations, and their differences.

ak