Use a temperature sensor to measure your skin temperature, and register the output with three LEDs. Even though the Arduino is a digital tool, it can interpret signals from an analog input, like the ...

Interfacing Temperature Sensor with ARDUINO: Captures temperature data using sensors like TMP36 or LM35. Interfacing an Ultrasonic Sensor with Arduino: Measures distance to an object using an HC-SR04 ...

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 ...