Creating a PC Fan Power Hub

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DIY PC Fan Hub


I recently ran out of fan power headers on my PC motherboard. A quick search online and about $12 later, I had a fan hub heading my way.  A few days later I had the fan hub installed in about 5 minutes and all my fans were adding to the office noise. The thing is... I couldn't stop thinking about how easy it would be to make.

Overview

Fast forward a couple months and I find myself in need of a way to hook up some 120mm fans for cooling purposes. This time I want to find out if building my own fan hub is worth the effort.

I have four 120mm PC fans that need to be powered. I would like to have the option of adding more fans later. I want to keep it cheap and simple. I will use a 12V wall wart and will add switch to power on and off. I had considered throwing a Nodemcu on it and making it a Smart fan hub. It might be a fun little project, but I have several Sonoff switches that I hacked and programmed for use with Alexa. You can see the Sonoff series at http://blog.kilomon.com/2018/01/hacking-sonoff-wifi-switch.html

DISCLAIMER: I am not an electrical engineer, so don't assume I know what I am talking about :)

Prep

Sourcing the Parts

The 4 pin CPU connector that you see on your motherboard is the Molex KK 47053-1000. I spent a considerable amount of time trying to find a knock off brand at a reasonable price. Individual prices ranged for 0.29 - $0.45 each. not including shipping and tax. I could go the bulk route using Mouser or Digikey, but that seems overkill. If you know of a more affordable source, drop me a comment.

The 3 pin connector was easier to find. (Some options I found http://amzn.to/2CegBHt http://amzn.to/2H4CPPQ)

In the end, I made a compromise. I bought these 3 pin connectors and will report on them when they arrive. In the meantime, I will use some standard 2.54mm PCB pin headers that I always have available. If you don't own any 2.54mm pin headers, its worth having some. They have become the de facto standard for creating shields and break out boards for MCU's.

Parts I Used

Purchasing all these parts will cost more than an off-the-shelf fan hub. I had these parts on hand and so there was no cost to me. However, if you purchase these parts, you will be able to use them for many other projects.

 I estimate the final cost of the parts I used to be around $3 (not including the fans).

Tools I Used

Some Design Options

There are some other ideas I thought of incorporating into this project:
  • Power Indicating LED
  • Power regulation and power conditioning (power supply fundamentals)
  • SATA or Molex connector for use inside a PC

Wiring

This is about as simple as you can get. This design has no power regulation and assumes the user is smart enough not to hook more than 12V and that they take precaution not overload their power adapter/wallwart.

Essentially, the male header pins are placed on power rails and power is controlled by the SPDT sliding switch.

Assembly

  • Start by snapping your male headers into 3 pins or 4 pins based on your fan connector
    • I tried both 90 pins and standard pins. I decided on standard pins.
  • Place the pin headers on the protoboard to find a good fit. I liked a 2 hole spacing.
  • Test connecting the fans to see how things fit
  • Next place the DC barrel jack and SPDT switch on the protoboard to make sure things fit (you can see I considered placing an LED as a power indicator)
  • TIP: If you have a DC barrel jack with lugs like shown in my pictures, place it on its side and hot glue to the board
  • Once you like the placement, start wiring things up.

  • Use some mounting putty or tape to hold the pin headers while soldering
    • Here you can see gaffers tape wrapped around the board to hold the pins
  • Using stripped bare 22AWG wire, I created the power rails
  • Once the first side of power rails was soldered, I test things
  • Happy with the first test, I soldered the bare wire power rails on the second row of pin headers
    • Please note I placed jumpers between the rails on the top side of the board


  • After testing a fan on the second row of pin headers, I hot glued the power rails for some added protection and add rubber feet for stability
    • Note that I did not hot glue around the switch solder joints just in case I decide to add that power indicating LED

Result

The fan hub is working great. It could be made better with an enclosure of some type. I have connected it to one of my hacked Sonoff's. I am now controlling my fans with Alexa and Alexa routines.



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