I'm facing an issue that I can't seem to resolve due to my limited knowledge in electronics. I'm working with a 4-channel 5V relay module and an ESP32 which operates on 3.3V. enter image description here

The setup seemed to work well initially but I have started experiencing some inconsistencies. One of the four relays is working perfectly fine, but the other three are not triggering as they should.

Here are the symptoms:

The LEDs on the non-working relays do light up when a signal is sent from the ESP32, indicating some form of communication. There is no audible 'click' sound from these relays when they are supposed to trigger. I noticed that if I gently tap the relay casing, the relay will sometimes trigger, and I can hear it closing. I had previously thought that I might have fried my first relay module so I replaced it, but the issue reappeared after a few days.

Any guidance would be greatly appreciated as I'm at a loss here. Thank you!

  • 2
    Is your relay board compatible with 3.3 V logic?
    – StarCat
    Aug 26 at 17:37
  • @StarCat i don't understand your question can you help me figure out or explain a bit more it's supposed to be powered by 5V DC but i'm limited to the esp32 board
    – Hach Rbh
    Aug 26 at 17:47
  • Maybe it is your code. Try posting a small example that reproduces the problem Aug 27 at 3:41
  • More questions here then you might think are because of under powered project using fresh but weak batteries. Almost always avoid using 9 Volt batteries. Certainly avoid them if a motor or relay is involved. How is this project powered?
    – st2000
    Aug 27 at 13:28
  • right now i'm using the usb type-C cable to power the esp directly how can i make the esp32 generate more power or make the relay use less current to be triggered
    – Hach Rbh
    Aug 27 at 16:14

1 Answer 1


So it turns out that esp32 boards can actually output 5v alongside with 3.3v output pin, You just have to use the VN pin which is used for powering the board when not connected through USB, this is not what the pin is intended for and also might cause some problems and you cannot upload code to the board when VIN pin is connected but so far it works perfectly and outputs consistent 5V that triggers the relays just fine.

Obviously, I was just looking for a solution no matter what risks it imposed, can anyone with a deeper understanding of this topic explain why the power input pin can also work as output and why is this not a feature that comes with esp32 boards

  • 1
    Hi Hach, The way this site works is one question followed by answers. You edit the original question to provide more information. Or you ask a new question separately. Aug 31 at 16:03
  • i answered the original question but asked if the solution i found is efficient and if it presents any dangers to the board
    – Hach Rbh
    Aug 31 at 23:02

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