1 #+TITLE: USB desk fan modification
2 #+author: Svjatoslav Agejenko
5 * (document settings) :noexport:
6 ** use dark style for TWBS-HTML exporter
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16 + DISCLAIMER: I DO ELECTRONICS AND 3D DESIGN SOLELY AS A HOBBY. THERE
17 COULD BE ERRORS THAT CAN RESULT IN ALL KINDS OF DAMAGE. USE THESE
18 DESIGNS AT YOUR OWN RISK.
20 + This design is released under Creative Commons Zero (CC0) license.
24 - Homepage: https://svjatoslav.eu
25 - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]]
30 - [[../../index.html][Other physical projects in this repository]]
31 - [[https://www.svjatoslav.eu/projects/][Other projects hosted at svjatoslav.eu]]
34 End-result looks like this:
38 It all started with couple of cheap USB desk fans that were a bit too
41 [[file:mini%20fan.png]]
43 Idea is to add DC-DC step-down converter to reduce motor voltage to
44 make it quieter ([[https://www.amazon.de/gp/product/B07K3W78SQ/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1][Purchased form here]]). And since I already have this
45 USB powered thing on my desk, why not to share this power to allow
46 charging of various other USB powered devices.
48 I ended up with this schematic:
49 [[file:schematic.png]]
51 USB power of 5 volts that enters the system via DC jack is distributed
52 to two USB-A connectors on the front panel. Note: USB data is not
53 connected. Therefore this hub is for power sharing only.
55 DC-DC fly-back converter could introduce voltage ripple in the
56 system. To smooth it out, there is capacitor (C1) and inductor (L1).
58 Step-down voltage converter has adjustable output voltage. So after
59 assembling, it can be tuned with screw-driver to reach desired
60 noise/airflow tradeoff.
62 From original fan I kept:
68 Engine is attached with screws to following back-plate:
70 [[file:fan%20housing%20-%20fan%20mount.png]]
72 And result is encased into pipelike case:
74 [[file:fan%20housing%20-%20cover%20assembly.png]]
78 + STL: [[file:fan%20housing%20-%20fan%20mount.stl][fan mount back plate]]
79 + STL: [[file:fan%20housing%20-%20cover.stl][pipe-like case]]
80 + [[file:fan%20housing.FCStd][FreeCAD project]]
82 Fan enclosure attaches to the rectangular body below using following
83 connector (glued to the fan housing):
85 [[file:fan%20housing%20connector.png]]
88 + [[file:fan%20housing%20connector.stl][STL file]]
89 + [[file:fan%20housing%20connector.FCStd][FreeCAD project]]
91 Bottom part to house 2 PCBs, on/off button and DC connector:
92 [[file:bottom%20stand%20body.png]]
95 [[file:make,%202.png]]
97 And is closed by cover:
98 [[file:bottom%20stand%20cover%20assembly.png]]
101 + STL: [[file:bottom%20stand%20body.stl][bottom stand body]]
102 + STL: [[file:bottom%20stand%20cover.stl]]
103 + [[file:bottom%20stand.FCStd][FreeCAD project]]
105 After assembly, it looks like this from the back:
106 [[file:make,%203.png]]
108 Note, part of the body is deformed during printing. I have heated bed
109 and I even printed raft support in Cura and it did not help. In my
110 experience black PLA filament is awful in comparison to transparent
111 one. Has inferior flow (results in slower print speed) and tends to
112 deform easily. Will never buy it again.
114 Fan top and bottom halves are attached using [[https://www.amazon.de/gp/product/B00OOLKD2G/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1][camera tripod quick