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:

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
Basic Schematic

 

 

 

 

 

 Now for the PCB Layout too

PWM Fan Controller PCB Design
PWM Fan Controller PCB Design

 

Partially Built Fan Controller
Partially Built Fan Controller

Lastly for the Code

18S20Tiny13Fan

Enjoy.

Update:  Below are a several cooling options installed using this fan Controller.