Relay not working?

I have a small hydroponics garden that has a tank of water that is continually circulated throughout. That tank tends to empty out, so I built a simple circuit to monitor the water level, and if it gets low, trigger a valve to open and refill it. It consists of 2 float switches in the tank, and an electronically controlled ball valve (not a solenoid). I originally had the valve hooked up to 12 v on one side, and a transistor network (6 transistors in parallel) to allow the ground connection through on the other side. This transistor network was activated by an Arduino Uno. I was originally planning on using a solenoid, which is why I used a transistor network. I have everything hooked up via ethernet cable and have a waterproof coupler in the middle so that I can unhook the electronics and work on it inside if needed.

The first coupler I bought failed within a month and there was corrosion everywhere. It turns out that this somehow fried my transistor network. I'm assuming that a 12v line crossed over somewhere. Anyway, I've replaced that network with a relay. The relay works fine out of circuit, but as soon as I hook it up to a load, it just hums and doesn't fully activate. It's powered by 5v and has a 5v line in that is normally pulled low. A high signal is sent to activate the relay. This is the relay that I have:


What could I be doing wrong? I apologize for my diagram... This is just a hobby!

Thanks,
Eric

It may be that when the valve operates, the voltage to the 12 V buck converter drops, and the 5 V supply reduces, so it is resetting the Arduino.

You could try running the Arduino from a separate 5 V supply.

Diver300 said:

It may be that when the valve operates, the voltage to the 12 V buck converter drops, and the 5 V supply reduces, so it is resetting the Arduino.

You could try running the Arduino from a separate 5 V supply.

Click to expand...

The valve that I have is power friendly. I don't think this is the issue, but I'll do some tests to make sure.

The actual schematic is unclear on the impedances and voltage for each stage. E.g. IR LED 5mA driven by what?

Not sure if you replied to the right post? There are no LEDs in my project.

I have solved the problem however. Stupid issue- I had a cracked solder joint that was causing a bad electrical connection to ground for all the pull down resistors and the relay board. It was under the board and was holding slightly, so hard to diagnose.
I appreciate the help!

Thanks!
Eric