Ok, my first project is a replacement for a previous gadget I’d knocked up to cool my devices under my TV, as they are in a new cabinet with very little vertical headroom.
The current one just adjusts the voltage to the 12v PC fan with the aid of a variable resistor, and a thermistor. Set to the right value, the voltage to the fan increases to its startup level when the temp goes a few degrees above ambient.
My brief for my Arduino powered one is to use a PWM fan, and adjusting the ‘duty cycle’ based on the analogue input from the thermistor. Also, I wanted to add an LED for feedback, and a transistor to turn off the fan completely when the temperature is around room temp.
As you can see, I’m not there yet. Stay tuned.