Can Vin pin damage Arduino if using it instead of 5V pin?

I am using NodeMCU board for my project. I noticed there are no 5V pins on it so i tried to connect ultrasonic sensor and servo motor on 3V3 pin. Off course, it didn’t work. When i put then on Vin pit, everything wroks. Can i damage board this way, because I thought Vin pin is used when there is an external power supply?

PS: Sorry for my bad English! :slight_smile:

Yes you can damage your system. Using Vin back feeds current through the 5V regulator, not a good idea.

Never try to run a servo or motor from the Arduino. That can damage the Arduino too.

NodeMCU board has no 5V pin because it's a 3V3 micro controller. The signals it sends out are also 3V3 :wink: Although some pins (NOT all) are 5V tolerant.