user68505: If I want to operate the NodeMCU on the 3.3V input with 2.5V to 3.6V; can I use any of the 3.3V pins to do so?


user31038: On the nodeMCU board all the 3.3v pins have continuity. That means they all do the same thing. And yes, you can apply ~3.3v to them. I have trouble with voltages under ~2.8 though, 2.5v is likely not going to work.
Use a buck+boost to keep it 3.3v if needed. For cheap dc/dc converters, I strongly prefer ones with XL semi chips; clean enough to please the ESPs.

68505: <p>If I want to operate the NodeMCU on the 3.3V input with 2.5V to 3.6V; can I use any of the 3.3V pins to do so?</p>
<p><a href="https://i.stack.imgur.com/li35f.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/li35f.png" alt="enter image description here" /></a></p>
 31038: <p>On the nodeMCU board all the 3.3v pins have continuity. That means they all do the same thing. And yes, you can apply ~3.3v to them. I have trouble with voltages under ~2.8 though, 2.5v is likely not going to work.</p>
<p>Use a buck+boost to keep it 3.3v if needed. For cheap dc/dc converters, I strongly prefer ones with XL semi chips; clean enough to please the ESPs.</p>
