Backstory:
My desktop pc is actually placed inside a desk compartment and living in a warm climate, its necessary to ventilate it with forced air. For this purpose I have installed 4 wire pc fans in the desk. The problem is fan noise, while in summer it’s not much of an issue due to ceiling fans overpowering the noise, but in winters, when ceiling fans are not working, this noise can be quite audible. To counter this issue, I have decided to make a DIY fan controller, that runs the pc pwm 4 wire fans on lowest settings to reduce noise, and burst at higher speed for some time, to force hot air out of compartment (Just in case if there’s hot air still inside compartment).

DIY Fan Controller working

Why not use ready made solutions? Although there are plenty of diy fan controllers on internet based on bareduino (standalone atmega328p using arduino software), all of them seems to be controlling fans at a constant speed. In my diy fan controller, there is a ds18b20 temperature sensor, based on which the microcontroller decides, fan speed to choose:

DIY Fan Controller Procedure

  1. if it’s hot, i.e. temperature above 27°C / 80°F
    1. NORMAL MODE
      • Led Temperature would turn on red.
      • Led fan would turn on blue
      • Fans would run at low (adjustable via potentiometer) speed
      • Bursts (full speed) after every 30 minutes for 1 minute
        • Led fan would turn on both red and blue
    2. QUIET MODE (Arduino digital pin 3 and 4 shorted with jumper)
      • Led Temperature would turn on red.
      • Led fan would turn off both red and blue
      • Fans would not run on low rpm
      • Bursts (at speed adjusted on potentiometer) after every 10 minutes for 2 minute
        • Led fan would turn on both red and blue
  2. if it’s cold, i.e. temperature below or 27°C / 80°F
    • Led Temperature would turn on blue
    • Fans would not run on low rpm
    • Bursts (at speed adjusted on potentiometer) after every 30 minutes for 1 minute
      • Led fan would turn on both red and blue

Download Code and all

Click here to download all (code, schematic pdf, board pdf, and gerber files if you wish to ) for arduino

schematic-diy-fan-controller
click to enlarge schematic
diy-fan-controller---3d-view-2-(1)
diy-fan-controller---3d-view-2-(2)
DIY-Fan-controller-pwm-pc-fan
bottom-copper---NOT-MIRRORED
Bottom copper, not mirrored – click to download pdf

Making the pcb with DIY CNC Router

One of my dream was to make a diy cnc router for making complex objects and millling pcbs. This way it removes the expanse and effort of working with Printer, transparencies, photosensitive sheet, and ferric chloride. With this diy cnc router, i can directly mill a pcb and use it. Its not a perfect machine, since this was my first setup, but its better than nothing and i was able to milll out a decent pcb.

fan controller pcb milled with DIY CNC Router
fan-controller-cnc-pcb-milled