Use Arduino to turn fan on / off I have a simple fan.
When I plug it to GND and Vin it spins.
I'd like to have the ability to turn it on / off with code.
Any example will do, as long as it gets it to spin.
I have a NodeMCU board, if that helps.
Depending of the type of fan you are using, two solutions exist. 


First one, use a MOSFET to drive the FAN from you nodemcu 
Second one, use a relay to drive the FAN from your nodemcu 


Things to consider :


The mosfet allow you to drive the fan without mechanical part moving. 
The relay require some transistor and feedback diode to be driven by your µc.