I wanted a simple Persistence of Vision (POV) device to display basic text messages at physics club events or in my office. Here's a simple solution you can build yourself!
(Note the blank area in the above photo is due to the scan rate of my phone's camera and the rotation rate of the leds! In operation the leds go all the way around the fan hub.)
The PartsAll Electronics has these Persistence of Vision (POV) 12V DC CPU fans that (I assume) go into gamer case mods. The product comes with a Windows-based executable program on a CD that uses the USB to connect to the microcontroller in the hub of the fan.
The fans have a 3-pin connector for power which i snipped off. The red wire is +12V, the black wire is 0V, and the yellow wire is a tach readout. I don't use this so I snipped this wire short so its out of the way. These fans require 12V DC and 0.09 Amps (for the 80mm version) so a simple power solution is to purchase a 12VC wall wart power supply with sufficient current capacity. You could remove the plug at the end of the power supply and solder the appropriate wires to the fan (use a multimeter to be sure!). Be sure to heat shrink the solder connections. (If this is all you want then jump down to the section about the stand.)
A wall wart power supply may be sufficient for a display that ever strays far from an electrical outlet. If you want to make the POV display more portable then you will want battery power. I decided to go with a light weight 12VDC rechargable battery (plus battery recharger) also from All Electronics. The recharger has a 3-pin female molex connector. I snip this off and expose the metal wires. A helpful user comment on the All Electronics' website informs us that the green wire is not involved in charging so I snip it back. The black wire is ground and the white wire is positive.
Since the 12V DC rechargable battery has 1/4-inch quick connect tabs I decided to use 1/4-inch quick connect male and female connections to use either battery power or wall-wart power. In the end the fan's power wires have female 1/4-inch crimp quick connects to batch the battery. The wall wart's wires have male 1/4-inch crimp quick connects to mate with the fan's power. Lastly, the battery recharger has female 1/4-inch quick connects.
You obviously need a crimper tool if you want to go this route.
The StandI wanted to mount the fan in a way that it would be stable and provide a good viewing angle of the POV message(s). I designed the following in FreeCAD and exported the file to a format that my Makerbot could print. (Of course, you could build your own stand out of wood or metal.)
I like FreeCAD for a no-cost drafting software solution that can also export stl and obj files to be read by a 3D printer such as the MakerBot desktop software which can create the makefile for actual 3D printing. I've included the makefile for the 80mm fan with this project. I used some bolts and nuts that I had in the lab to secure the stand to the fan. The diameter of the through holes on the fan and stand are 0.175-inches so choose an appropriate bolt size and length.
The EndAnd that's it! Show me some clever stands or messages that you create with your POV display in the comments below.
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