Thank you for the reply!
jremington:
You need to power the relays separately. Any change in the supply voltage to the Arduino will change the analog input reference voltage, by default.
I suggest to use 5V step-down regulators so that everything is powered by the 12V supply.
Isn't it the same that I have already done? From the image that I uploaded, you may see that I supply the breadboard by a 12V, the 12V is regulated to 5V and 3.3V. The arduino and relays get the power from the 5V.
I understand that I need to power the relays separately, but I do not get how to power arduino and relays from the 5V step-down regulator.
jremington:
Connect all the grounds, and make sure that you have an inductive kick diode on the pump.
Is this used to protect against the reverse current of the pump?
