(SOLVED) 5v relay not powering arduino or rest of system


This is my first arduino project and I need help

Here's a pic of my system with the wiring.

When I plug the arduino via USB, the system turns on, however when I plug the 12 v 5 amp power supply (where the 12v battery is in the diagram) nothing happens. As if the system is not plugged in at all.

The 12V battery only powers the Gear Motor. There is no connection to anything on the coil side of the relay.

thanks for quick reply. I would assume that the VCC pin on the relay that connects to the arduino 5v pin would power the arduino up, am I assuming wrong and what can I do to fix it?

The task is fraught with danger, as the motor will generate a lot of interference through the battery, to the Arduino if you try powering it also from the battery. The simple way is to connect the battery + and - also to the barrel jack on the Arduino, a better way to use a step down converter and apply the output to the 5V pin of the Arduino. You can try it just to see something run, then think about the possible noise issue.

Probably, I'm guessing VCC on your relay module is connected to Arduino 5V. So it's the same electrical connection. Don't forget all the grounds.

thanks, you're correct, the vcc from the relay is connected to the 5v pin of the arduino but doesn't power the system. If I used a step down converter from the battery and connected it to the 5v pin it would have the same result right (ie not work to power it)? Thanks for your help, I am a complete beginner so might not be fully understanding your response

No, I made the converter suggestion because it probably would work. Don't forget the grounds. Make sure the battery can supply enough power for the motor.

When you power the Arduino from the USB, Vcc on the relay board gets power from the 5V pin, the other direction of power flow.

Similar setup.

Good diagrams, but just for the OP, realize the bottom picture doesn't show the Arduino power supply, which is separate. That is where the yellow coloured conductors are powered from.

If you wanted to try the one supply, you would just disconnect any USB and place a jumper on JD-VCC.

That makes a lot of sense, I've decided to use a step down converter and run it off the same supply. Thanks for your help!

Thanks Larry!

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