ESP8266 Community Forum

- Tue Sep 24, 2019 11:55 am #83912 hello,

Can I safetly power the node mcu from an external 3.3V source and at the same time connect the usb?

- Tue Sep 24, 2019 12:10 pm #83914 As long as both are powered up you shouldn't have any problems.

Of course I don't know anything about your 3.3 volt supply.

- Wed Sep 25, 2019 1:30 pm #83921 Thanks!

- Wed Sep 25, 2019 2:15 pm #83922

Power to the NodeMCU v2 is supplied via the on-board USB Micro B connector or directly via the “VIN” pin. The power source is selected automatically.

The board must have a power management chip and the 3.3V will be disconnected.