Have read a lot of different things online, and I just ain't sure yet.
I'm trying to hook up a NodeMCU to control some relays. And want to power the NodeMCU by the VIN pin.
Anyone know if this setup is possible?
Or should I do it in another way?
enter image description here

  • Is it necessary to use the JDVCC at all when I use this setup? Maybe I can keep the jumper on VCC/JDVCC and only connect to the VCC on the relay?
    – John
    Commented Apr 6, 2021 at 9:32
  • you would use JDVCC with separate power supply for relay coils. then you would not connect the grounds. main reason would be to prevent EMI from relays switching
    – Juraj
    Commented Apr 6, 2021 at 9:53
  • So what you are saying is that, for my setup, I don't need to use JDVCC?
    – John
    Commented Apr 6, 2021 at 9:57
  • I see. For my setup, I will only be using max 2-3 relay at the time
    – John
    Commented Apr 6, 2021 at 10:20
  • 24VAC to control some irrigation valves
    – John
    Commented Apr 6, 2021 at 10:28

1 Answer 1


Looks fine to me, I don't see any issues, assuming the PSU has sufficient 'grunt' to power both, and most will have.

  • I'm using a 24VAC to 5VDC 3A converter as the PSU supply
    – John
    Commented Apr 6, 2021 at 9:30
  • Plenty of surplus power there, you shouldn't have any issues
    – Bra1n
    Commented Apr 6, 2021 at 10:03

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