# NodeMcu ESP8266 Lua V3 rev1.0 - how to power Vin pin

Hi all,

I am a newbie, starting exploring Arduino projects.
I recently received NodeMcu ESP8266 Lua V3 rev1.0 and want to use it for simple beginners projects.
So I started looking into documentation and one of first steps was to clarify options how to power it up.
At this point I am looking to power board via Vin pin by applying 5V which should used on board voltage regulator to supply 3.3V logic for the board.

However, looking into information on internet I am a bit confused.

According to GitHub - nodemcu/nodemcu-devkit-v1.0 I found that 5V should be applied.
According to NodeMCU ESP8266 Pinout, Specifications, Features & Datasheet
specified voltage is 7-12V
and I think I also saw some sites where there is recommended voltage for Vin 6.5V - 10V.
In some forums people debating about applying voltages of 14V or so.
Anyway, a lot of opposite information and for a beginner and I am not sure what to follow.

1. I would appreciate if someone could help me which board documentation I should follow?

2. I try to find an answer how to power Vin by myself. I look at the board components and noticed that board have voltage regulator AMS1117. Than I look at the datasheet for this voltage regulator: AMS1117-3.3 datasheet
Accordingly, dropout voltage at 800mA should be 1.3V.
Which means that MIN voltage applied should be Vin_min = 1.3V + 3.3 = 4.6V
So it should work for Vin = 5V.
What about the voltages above 5V?

On page 2 it states the maximum input voltage is 15V. But the higher the input voltage, and the more current your circuit draws, the more danger that the regulator will overheat and either shutdown or fail. Linear regulators like these reduce the input voltage down to the required output voltage by turning the extra power into heat. They are quite small devices and the NodeMCU board is small and crowded, so it's not easy for that heat to dissipate away. So keep the input voltage down as low as you can, 4.6~5V is ideal. If you need to run from, say, 12V, better to use a DC-DC "buck" converter. Adjust that to 3.3V and power the NodeMCU through the 3V3 pin. If you need 5V for other components, set the converter to 5V and connect that to the Vin pin.