Hello (again)
So I finally connected my 16 channels relay board to 2 of those 74HC595 shift registers! It's cool and all!
But I have an little problem, the board is Active LOW and I want it Active HIGH. So I've read about using NPN transistor arrays such as the ULN2803. Guess what? There are 2 of those on the relay board! And even better, they are mounted on sockets.
So I'm wondering... If I remove those chips and replace them with wires, like that:
Would that work? Is it as simple as that? Please tell me if my schema is correct, or else, what do I need to do (I don't want to try and fry the board!)
Also another little problem with this board:
On the main connector (where are all the input pins) there are two GND pins (and two 5V pins).
The board only works correctly when I connect one of those GND pin to the Arduino GND. But then, when I power the board while the Arduino ISN'T powered, then the Arduino receive some current from the board because the "on" LED of the Arduino is lighted but not fully (and the program don't run).
What can be the problem and how do I solve it? Do I need to connect this GND pin somewhere else, such as on the GND of the 12V power supply of the board (where is connected the GND of the 230V main current)?
Thanks in avance!