I am in need of 12VDC from my Wemos D1 R2. How do I configure the Vin pin to output the max (I think its 12VDC)?

board: Wemos D1 R2 V2.1.0 - ESP8266 (LOLIN D1 R2)

Pinout here in pictures below

  • Your Wemos D1 cannot generate a higher voltage than what is provided as input (via the barrel connector). It will only output 12V if you connect your own 12V power supply to the barrel connector.
    – StarCat
    May 17, 2020 at 14:49
  • you should learn how to use a mosfet as a switch in these types of situations.
    – dandavis
    May 21, 2020 at 15:34

2 Answers 2


You cannot. You are misunderstanding, what that pin is. Vin means Voltage In. It's a voltage input, connected to a voltage regulator, which will regulate the provided voltage at that pin down to 3.3V for the Wemos to work with. It is not an output. The regulator cannot convert the 3.3V from the Wemos to 12V. That is not, what it is build for.

To get 12V you either need a separate 12V power source, or you need to buy a stepup/boost converter, which brings the 3.3V (or 5V, if you are powering from USB) up to 12V. For the latter, be sure, that the converter and the source, where you get the input voltage of the converter, can provide enough current for your use case.


After looking into it and seeing all the previous answers, I noticed the Vin pin can be used as an output but only up to the input from the barrel connector.

When using a 9V input to the barrel jack, the voltage difference between the ground pin and Vin pin was just under 9V. Similarly, when measuring the voltage difference when using a 12V supply, the multimeter reported just under 12V.

This is in line with @StarCat comment.

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