You also need to select the transistor by the type of fan that you use. In my case I used the well-known BD139 transistor and a 9V battery to provide power to the fan and transistor. The LM35 ...

AHT10 Temperature & Humidity Sensor. ... I can live with it, i.e., by wiring a single sensor to the I 2 C line. Here is a crude schematic of the AHT10 module (borrowed from web). Arduino & AHT10. ...