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Can we use the vin pin of the lolin v3 nodeMCU as a 5V supply. If yes, i checked mine with a multimeter. At max, it gives a voltage of 2V. Is my pin blown out? Also, can use the VU pin as a 5V supply? Will using it cause any problems to my laptop's USB port? Can somebody help me out?

I need 5V to drive a relay using the v3

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  • In addition to the voltage, you need to think about how much current you’ll need. That’s the bigger driver of whether or not you can use pin as a source.
    – Delta_G
    May 13, 2020 at 18:27
  • no, but you can use the same pin on an Amica nodemcu (which all seem to use a cp2102 instead of ch340), that's connected to 5v on the usb through a diode that handles about 400ma safely. for this reason alone (powering 5v periphreals while running from usb power), i never buy the the larger lolin boards, except accidentally when listings are deceptive.
    – dandavis
    May 14, 2020 at 17:29
  • So the Vin of V3 doesn't support 5V output?
    – Yash Shah
    May 16, 2020 at 16:50

1 Answer 1

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On the NodeMCU “v3” (and only on the v3) there’s a pin called VU (Vusb) that is connected to the +5V on the USB bus of the NodeMCU socket. This pin can be used to feed external components when it’s connected to USB, within the limits of the USB power supply it’s connected to.

The Vin pin (which is available on all NodeMCUs (and not just the v3) is a +5V power input which can be used to power the NodeMCU if it is not connected to USB. It can not be used as an output and it needs a stabilized supply.

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  • The previous versions do give 5V from the Vin pin. I've driven sensors using them. The V3 also has been used for the same. I was informed by my employer.
    – Yash Shah
    May 16, 2020 at 16:50
  • Strictly speaking, the Vin pin is less than 5v because it steps down to about 4.76V because of a Schottky diode (see circuit diagram)
    – S. Imp
    Jul 7, 2020 at 6:40
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    The VU is useful for example to power 5 V relay modules, which at 3.3V, usually work but are slower and less reliable.
    – FarO
    Jul 15, 2021 at 8:06

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