I'll have to use such setup, but are there anything smarter?
how do I figure out the resistors R2 and R3?
I measure approximately 15V as I should, but when they're of I measure -9V.
if I remove the led, and still measure at the two points marked, I measure 15V when Arduino I/O high, and 0V when low
Oh dear!Mike is not going to like you using them in parallel and without current limiting resistors.
Each led-pcb draws 75mA when connected to a 15V power supply.
Dream on sunshine.