when the relay that connect to dc water bumb 12V the LCD print a random characters
Show us a good schematic of your proposed circuit.
Show us a good image of your ‘actual’ wiring.
Give links to components.
don't put the LCD or its wires close to the relays and high current
all relay and LCD connect to one Arduino in my picture so i need second Arduino ?
I mean not physically close
are you powering the relay from the Arduino ? they can draw lots of current
We cannot see the whole setup.
Last time:
Show us a good schematic of your proposed circuit.
Show us a good image of your ‘actual’ wiring.
Give links to components.
The pump (I presume you meant pump) is an inductive load and will need snubbing (as with a free-wheel diode across its terminals), otherwise switching it off will generate a large voltage spike due to inductive kick-back.
Can you give details of all the hardware like pumps, supplies, and how they are wired together.
Yeah, we get that sort of question all the time.
So would this second Arduino be connected to the first in any way?
If there is no connection at all between the two, then the interference will probably not be transferred from one to the other.
There might however be a different problem. 
Try a 100 µF capacitor directly across pins 1 and 2 of the LCD. Also make sure all the connections between the UNO and the LCD are tied together in a single bundle all the way between UNO and LCD. And the same for all connections between the UNO and the relay board.
are you putting more than 5V? When noise appear, immediatley stop as it will short circuit. What is your project puropse?
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.