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For one of my hobby projects I would like to use:

to control the 24V (19W) mist maker.

My current wiring is this: enter image description here

As you can see the both grounds (12V and 5V) are attached to the com connector of the power supply.

I wonder whether grounds should be decoupled (for whatever reason) - i.e. to use separate power supplies? If the above wiring is OK I would really like to know in which circumstances (if any) a separate power supplies would be needed.

Thanks for all your answers in advance.

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  • Please let me know if any additional information is needed. – PrimosK Apr 4 '17 at 15:28
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    I am not sure, if a question about grounding should have been migrated here. D1 mini is not an Arduino and there aren't even any references to Arduino core firmware being used. – gre_gor Apr 4 '17 at 17:32
  • @gre_gor I understand what you mean but a Wemos D1 Is programmed through the Arduino IDE by default (that's what you mean by the core firmware?) So this is the right place for this board. However I think this is really an electronics question, but ... – Code Gorilla Apr 6 '17 at 12:08
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That grounding scheme looks right since the Load ground is coupled back to the supply separately from the logic ground.

The only reason you would separate supplies would be to isolate them for safety or other reasons. For example, if the load side was a large or ac voltage.

Isolation requirements vary with application so it is hard to be more specific than that here.

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    I agree. EMI noise from ultrasonic ~1A current may or may not affect other high Z inputs, which may benefit from twisted pair wires or shielded pair for power and decoupling LC filter near load. – Tony Stewart Sunnyskyguy EE75 Apr 4 '17 at 15:44
  • I tested this wiring out and it seems that there are no issues with EMI noise. So all good. Thanks for answering this. – PrimosK Apr 4 '17 at 17:00

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