[Thampitakky]

Hi all,
I have a project that meet some problems. I have tried to make adjustments all I can, but still have some problems that I don’t understand. I am using an arduino uno to control nine relay modules (4 double and one single). I power everything with a power supply (12v 30A). The relays are powered from this through a voltage regulator (5 volt) and the arduino with a jack from the power supply.

When I power it up it is almost like one of the relays are floating or something, it flickers on and off when it should be on. When it’s off it stays off, so it is when it receives signal from the arduino.

Added:
Tools and code programming from Arduino Relay Module Use Step by Step.
Source: https://www.kukelec.com/how-to-use-r...duino-uno.html

Anyone has ideas?

[hfjbuis]

Did you connect the Arduino gnd with the relay ground.

You probably used a relay module board. The voltage rating of the relay on this board should match the supply voltage at the Arduino side of the board. Because the Arduino can output 5V, these relays should be 5V relays.

These relay modules have a jumper to power the relay from the logic voltage (Arduino side) or a dedicated power supply. Check if your board has such a jumper and if it is connected.

Maybe the relay board is malfunction. Replace it with one of the other boards to see if the problem is the relay or the Arduino connection.

Did you use an output pin that is also used for serial/USB communication?