I got a question about externally powering my NodeMCU V3. It has an onboard voltage regulator (3v3) which breaks out to 3 header pins. Now I want to power 3v3 from an external board. Can I supply 3v3 to all of those pins at the same time? (Basically connected in parallel). Anyone has done this before or has this experience with NodeMCU V3?

I have supplied a link below: https://www.theengineeringprojects.com/2018/10/introduction-to-nodemcu-v3.html

Thanks a lot!


Yes, you may connect all 3V pins together (red) and all GND pins together (black), like so:

3V pins connected together

In some cases, more wires will improve the circuit. E.g. when you build the Ben Eater 8-Bit CPU, you'll find that connecting power in a ring instead of a line will reduce voltage drop by about 50%.

When first reading your question, I got the impression that you wanted to solder the 3.3 V wires directly to the voltage regulator. Here's my original answer for that:

That's not a good idea: if you connect the same wire to all pins, your're creating a short, typically causing a malfunction if not worse. You may destroy your equipment (external board as well as the NodeMCU v3). Do NOT connect 3.3V to all pins of the voltage regulator.

A voltage regulator has 3 pins:

  • voltage in (for an unregulated voltage you can't exactly control; typically higher than the output voltage)
  • voltage out (for the stabilized resulting voltage you want to have)
  • ground

The only pin to connect the voltage to is the "voltage in" pin (VIN). And typically, a development board has a pin for that:

VIN pin on a 8266 development board

However, you'll find that the input voltage must be between 4.75V and 10V, so supplying 3.3V from an external board is not sufficient.

If you have regulated (stable) 3.3V already, you can connect that to a pin labelled 3V:

3V pin on a 8266 development board

Also, you need to connect the grounds (GND) of both circuits together (GND of external board to GND of NodeMCU), otherwise the current will not find its way back.

  • I don't believe the OP wants to short the regulator, but externally apply 3V3 to the circuit – Sim Son Jun 6 '20 at 0:54
  • Hi! Thanks for your replies! Like Sim Son said, I would just like to externally supply the 3V3 pins with a voltage regulator. Would it hurt if the 3, 3V3 pins are tied together to the same net? Would it give me problems? – sanrays10 Jun 6 '20 at 8:43
  • @sanrays10: yes, that's possible. I've updated the answer and uploaded an image where I did exactly that. – Thomas Weller Jun 6 '20 at 9:54
  • Thanks a lot! Just what I needed to know! – sanrays10 Jun 6 '20 at 22:04

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