USB desk fan modification

• DISCLAIMER: I DO ELECTRONICS AND 3D DESIGN SOLELY AS A HOBBY. THERE COULD BE ERRORS THAT CAN RESULT IN ALL KINDS OF DAMAGE. USE THESE DESIGNS AT YOUR OWN RISK.
• This design is released under Creative Commons Zero (CC0) license.
• Authors:
  • Svjatoslav Agejenko
    • Homepage: https://svjatoslav.eu
    • Email: svjatoslav@svjatoslav.eu
  • Valeria Agejenko
• See also:
  • Other physical projects in this repository
  • Other projects hosted at svjatoslav.eu

End-result looks like this:

It all started with couple of cheap USB desk fans that were a bit too noisy:

Idea is to add DC-DC step-down converter to reduce motor voltage to make it quieter (Purchased form here). And since I already have this USB powered thing on my desk, why not to share this power to allow charging of various other USB powered devices.

I ended up with this schematic:

USB power of 5 volts that enters the system via DC jack is distributed to two USB-A connectors on the front panel. Note: USB data is not connected. Therefore this hub is for power sharing only.

DC-DC fly-back converter could introduce voltage ripple in the system. To smooth it out, there is capacitor (C1) and inductor (L1).

Step-down voltage converter has adjustable output voltage. So after assembling, it can be tuned with screw-driver to reach desired noise/airflow tradeoff.

From original fan I kept:

• engine
• blades
• DC jack
• on/off swith

Engine is attached with screws to following back-plate:

And result is encased into pipelike case:

Download:

• STL: fan mount back plate
• STL: pipe-like case
• FreeCAD project

Fan enclosure attaches to the rectangular body below using following connector (glued to the fan housing):

Download:

• STL file
• FreeCAD project

Bottom part to house 2 PCBs, on/off button and DC connector:

Component attachment:

And is closed by cover:

Download:

• STL: bottom stand body
• STL: bottom%20stand%20cover.stl
• FreeCAD project

After assembly, it looks like this from the back:

Note, part of the body is deformed during printing. I have heated bed and I even printed raft support in Cura and it did not help. In my experience black PLA filament is awful in comparison to transparent one. Has inferior flow (results in slower print speed) and tends to deform easily. Will never buy it again.

Fan top and bottom halves are attached using camera tripod quick release screw.