to cyclegadget
Thank you.
I didnt know that.
I have no idea about electricity.
You mean
when arduino has negative connection and no postive power,
positive to D2 makes problem.
right?
So,
like this?
Thank you. you saved my life.
But.
I do worry about positive.
I can't explain,
I just know(think? heard?) that everything has ground.
I think
Device connected GND only - Hmm, It's OK. It has no electricity.
Device connected Positive only - Oh, It's dangerous! it will be fire!
am I wrong?
===
I did wire it as new one.
It has problem.
If i connect power to new wiring,
then tick,tick,tick,tick,tick,tick,tick, relay switch rapidly.
I dont know why.
if I push the button to turn on arduino, it works.
And LOW to D2(close relay, turn off arduino),
then tick,tick,tick,tick,tick,tick,tick, switch rapidly again.