NE555: Odd discharge behavior?

Hello J, welcome to the TI e2e forums.

I would not expect this on a circuit board with a proper bypass capacitor. Is this bump also on pin 1?

Do you have a bypass capacitor between pins 1 and 8? Is this on a circuit board or a 'breadboard'?

Hi Ron.  I believe I have a bypass, I’ll double check, and also look at pin 1.  This is on a breadboard.  Here’s a bit more detail; top = pin 3, bottom = pin 7:

I assume there’s a current spike when the comparator flips; is that the likely source?

Thanks ~ J

J,

J Hagerman said:

there’s a current spike when the comparator flip

Yes, there is and that is the source. 

That's why I suspect bump is also on pin1 (keep scope ground where is has been).