I recently bought this cheap 4 channel relay board:
It behaves differently from the 1 channel relay board I already had:
My old relay board would close if supplied with 5V (HIGH) on it's pin.
This relay board closes when a pin is connected to ground (0V LOW).
Is there an explanation why some board close on HIGH and some on LOW?
In my mind it seems more logical to close the relay when supplied with 5V (HIGH) and not the other way around.