First of all I’m a beginner of electric but something is not clear to me.
I bought 16 12V relay board with optocouplers. If I connect the arduino +5v GND and IO pins to the board I just wonder the relay board powering the arduino itself. I see the 5v regulator on the relay board, but normally it should power only the optocoupler collector emitter site. I thing between the arduino power and on board 5v regulator missing a DCDC 5v to 5v isolator.
Can this board make any noise problem or it is perfect?
16 RELAY.pdf (491 KB)
16 relay 2.pdf (55.1 KB)