I finally finished one of the outdoor Power Supply Boxes. It contains 2x 350W SMPSs in it and will be situated in the garden. The cabinet currently has a 12v computer fan to push air out of the box. Like all good computer fans this one makes a racket.
So I have set out to make a simple fan controller.
Design Requirement:
- Operate of 12Volts
- Keep fan OFF until needed
- At 40degree ( this is my first guess) turn the fan ON slowly)
- At 60degree and above make the fan go flat tack.
- Between these two set point, the fan speed is to be set proportionally
- Capable of driving 3 80mm or 120mm fans
the Temperature measurement can be super easy using a thermistor is a basic voltage divider. I have Atmel ATTiny 13 what have ADC and PWM functions.
Update 1:
I scraped the Thermistor idea and went straight toe Dalas DS18S20. I have a number left over from a previous project.
Basic Schematic
Now for the PCB Layout too
PWM Fan Controller PCB Design
Partially Built Fan Controller
Lastly for the Code
Enjoy.
Update: Below are a several cooling options installed using this fan Controller.