5v 2 channel relay suddenly stopped working


I am working on a project that uses a 2 channel5v switching relay to change direction of a motor, based on arduino sensors. It was working fine then suddenly stopped, I have tested the motor, power supply, and relay and they all work individually.

The relay lights indicating a switch turns on at the right moments, however, there's no clicking sound. It seems like the output side isnt getting any power. I have tested the system with a 2nd relay and that also doesn't work. Has anyone encountered this issue before?

Please post a schematic of your project and specifically indicate the power source that needs to energize the relay coil.

Heres the schematic. The power supply is a 12v 5 amp laptop style. Thanks for your help

Well, I'm not surprised that the project doesn't work. The Arduino is unpowered according to your schematic :wink:

All joking aside: I see you're driving the relay coils from the 5V pin on the Arduino. You probably (???) power the Arduino through its barrel jack - if so, with what voltage? The same as your 12V laptop supply? This is exactly why I asked because in all likelihood you have burned out the voltage regulator on the Arduino if you did what I suspect you did.

An Arduino board is NOT a power supply. It does NOT work as a source for energizing relay coils.

hahaha, yea I powered it from the same laptop supply using a barrel jack, so most likely the arduino is fried? I was told it can handle voltage from 5-12v. I am going to switch to powering the arduino on 5v phone charger through the usb port moving forward.

I am supplying voltage to the relay separately on the output side, so I would have to supply the input side with 5v as well? how would I go about doing that? I am kind of newish to electronics and not fully confident with the best/easiest way to do that. TIA

Not 5V, too low.

The barrel jack can handle 7V to 12V , however, 7V to 9V is better.

As @LarryD says, it can 'handle' voltages of 7~12V but 7~9V is a safer guess, and I would add to this that this is only true/reliable if the Arduino only has to power itself and maybe one or two low-power sensors. Once you start drawing significant current (and the 75~250mA a relay coil draws, depending on the type used) is way beyond what you should let the Arduino supply if you feed it through its barrel jack.

So yeah, I would recommend to split things up, and that's pretty simple:
Keep your 12V laptop supply for the 12V components.
Get a 12V --> 5V DC-DC buck converter. Connect it to the 12V supply and connect its output to the 5V pin on your Arduino and the Vcc/5V pins on all modules that use 5V. This includes the control-side of the relay board. So the Arduino gets its power along with the rest of the devices from the 5V DC-DC converter.

thanks, that makes sense. I am confused on one part: so then I would be powering the arduino from the 5v pin or do i still need to connect 5v supply to the barrel jack or USB port on the arduino?




awesome, thanks so much!

If you apply 5v to the Arduino 5v pin, make sure the USB plug is not plugged into your computer.

so going the 5v pin route, it would be quite difficult to connect the arduino to the computer for troubleshooting and testing the system, right? and i wouldn't be able to use the serial monitor feature of IDE.

Yeah, that's a drawback. So alternatively you could use the barrel jack to power the Arduino and power all the rest of the 5V stuff from a DC-DC converter.

Ok great, thanks for your help!

Not difficult at all. Just disconnect the "5V" pin from the 5 V supply (which still connects to the relay board) whenever you plug the USB in to the PC. :+1:

Laptop supply? Those are really high voltage, like 19-25V.

Its a 12v 6amp supply

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