@davee interrupt 0 is digital pin 2. Interrupt 1 is digital pin 3. It is working fine now.

@will I believe I blundered into the solution. I began playing with the size of the LED resistor and found that varying its' size had a profound effe...

@will This is embarrassing. When I tested it, I had forgotten to move the LED to Pin 8, so no LED was connected to it. As soon as I put the LED in pl...

@will Thank you, thank you. I used Pin 8 instead of 6, as you suggested, and that solved the problem. no doubt you can tell I am not wise in the w...

@zander I did change it. no line number shown in the post, so ; flowRate = count; Serial.print("count4 = "); Serial.println(count); ...

@zander no, the count goes much higher from loop two on. whether I use count++ or count = count+1, it won't work unless I comment out the digitalWri...

@will thanks for the suggestions. I did change the attach interrupt syntax. but I had already tried it both ways many times. it is my understanding t...

@zander My recount of events was no doubt vague. I can't recall if i always had the cap in place when i had these problems, but i think ruling things...

@davee thanks. i'll mull that over.

@davee Hmmm. I have been having weird, intermittent, error messages while running my arduino sketch, and failure to load at other times. The sketches...

Yes. thanks. that is what I was referring to. I had just made a screen shot showing the same thing. I was so new to the drone bot workshop that I th...

@zander Maybe I'm using the wrong term. Just below the video, in the comments section is the comment i'm referring to. it seems to have some preceden...