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Topic: Two supplies Common Ground and current draw Question (Read 241 times) previous topic - next topic

savatage

Hi All,

I have Power Supply A (12V 5A) to power 6 arduino's.

I have Power Supply B (5V 15A) to power 2 metres of 144 LED/m neopixel strips.


The current draw on Power supply B could be around 13A and Power supply A does not draw much at all. I understand that I need a common ground between these supplies for the logic levels.

Is it safe to connect the negative terminals of both supplies together?

Or Would it be better to branch off negative connections from Supply B to the GND of each of the arduinos?

Thanks in advance for your answers 

Paul_KD7HB

If they are like my power supplies it would be fine to connect the - on each together, but with yours, who knows. Warning, the - wire for the 15 amp supply carries the same current as the + wire, So both need to be an adequate gauge wire.

Paul

TomGeorge

Hi,
Connect the two negatives at the power supplies, this will prevent gnd currents from the high current supply causing volt drop problems with the lower current controller wiring.

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

savatage

Thank you Tom and Paul for your responses.

@Paul I am using the same 14-gauge wire for both supplies so It should be fine.

@Tom Thanks! I'll connect the GND of both supplies. I am guessing not a lot of current should be flowing through this GND branch? Would that be a correct assumption?

Regards,

TomGeorge

I am guessing not a lot of current should be flowing through this GND branch? Would that be a correct assumption?

Regards,

There will be a relatively heavy current at the branch, which is why you put it at the power supply gnd junction that should be as close to the power supplies as possible.
Tom.... :)
Everything runs on smoke, let the smoke out, it stops running....

savatage

Thanks for responding Tom.

There would be no danger of that heavy current damaging the 12V power supply or the Arduino's connected to it?

TomGeorge

Thanks for responding Tom.

There would be no danger of that heavy current damaging the 12V power supply or the Arduino's connected to it?
No..
Everything runs on smoke, let the smoke out, it stops running....

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