USB desk fan modification

1 General

2 Project description

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: schematic.png

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:



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



Bottom part to house 2 PCBs, on/off button and DC connector: bottom%20stand%20body.png

Component attachment: make,%202.png

And is closed by cover: bottom%20stand%20cover%20assembly.png


After assembly, it looks like this from the back: make,%203.png

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.