Grumpy_Mike:
Never guess in electronics. That circuit will not work.
Yes, that is what I ment. When arduino outputs +5 volt, it grounds the first transistor (2N2222) and then the S8550 is grounded and should then lead between collector and emittor?
That's why I asked, But is there a reason why it don't work? Are you thinking of the whole circuit or the two transistors?
Do you maybe have a better way to do it? 