Digital thermometer with fan control

Digital thermometer and hydrometer through DHT11 sensor. Control with arduino nano, it has an LCD1602 display and allows adjusting the temperature at which the fan is activated in the arduino program. This is very useful for example to control the ambient temperature of a closed 3D printer to print correctly with ABS. The temperature sensor can be removed from its holder and, with a longer cable, mounted in the area where you want to measure the temperature.
To adjust the fan activation temperature you have to edit the arduino program.

Components:
- Arduino nano
- LCD1602 + I2C display
- DHT11 Temperature and humidity sensor
- 2N222A transistor
- 330 ohm resistance
- 3 units 3.7v AA size batteries
- 14mm button switch
- Charging port
- Battery holder of 3 units AA size
- Prototype board 60x40mm
- Wires
- Bolts M3 and M2
- 12 v fan (optional)