This month I received my first Alien3D UFO subscription box. The monthly subscription includes test filament, a printer accessory, and a cool electronics project that is meant to be combined with 3d printing. This month’s project is a Persistence of Vision display. In this post, I will document the steps I took to assemble this project. Part two, coming in the future, will focus on fixing it after knocking off my workbench before I had a chance actually to video it in action…
Persistence of Vision
Persistence of Vision (POV) is the effect the eye/mind uses, making a light look like it is continuously lit even though it isn’t. Things such as animation work off of this optical illusion. In this case, the POV display is spinning around, and the LED’s light up for a millisecond every rotation. Since the LEDs are blinking in the same location each time, the eyes/mind think the light is solid. The upshot of this effect is that things can be written on this spinning display and made to look solid.
Most everything needed for this project was included in the Alien3D subscription box. The build is based upon the instructable Alien3D used as a guideline.
Below is a list of the components. Alien3D did add two on/off switches to the build. I thought this was a great addition. Plus, the motor shipped with the subscription is slightly different than the one in the original instructable. The only thing I added was the screws and heatshrink.
- Arduino Nano – with pin headers
- IR Sensor
- 8 LEDs
- 8 220 Ohm resistors
- Breakout board
- DC motor
- 2 9V battery clips
- 2 on/off switches
- 10 wires – M-F jumpers were included, with the M side being clipped off
- 2 M3 screws
- 8 small shrinktube pieces
The following pieces have to be 3D printed. Notice, these are different between the original instructable and the Alien3D build due to other DC motors being used.
- Motor Top
I chose Real Black PLA from 3D Solutech to print out the parts.
Assembly is pretty straightforward using the instructable instructions. The main difference I did was to add shrinktubing over each resistor coming off of the breakout board. I felt this made it look nicer and reduced the chance of any positive leads from shorting out.
Before doing this project, I tested it on a breadboard and played with the code a bit (mostly so I could learn something). I had to change the timing for each LED so I could see it without the LED spinning. Basically, before I soldered that many joints, I wanted to ensure it was going to work. It did.
Here is what the back of the display arm looks like after assembly:
If you look closely, you can see the shrinktube over the resistors. I had to cut two rows off the breakout board for it to fit in the assembly. Plus, I put just a dab of hot glue on the breakout board and the IR Sensor and power switch. The power switch is between the positive battery terminal and the Arduino Nano. The Nano and battery are held in by electrical tape. I did not want to hot glue them into place.
Here is a look at the whole thing before I connected the arm to the motor. I used a zip tie to clean up the wires going to the motor, and another to mount the power switch.
You can see where I used two M3 screws to connect the motor top to the base. Plus, the motor barely fits in the motor top. It is not going anywhere once you get it in!
Part Two Coming Soon
After I fix the damage caused by knocking the POD display off my bench, I will do a post showing my final code and a video of it in action. I only made slight modifications to the code, so anyone doing this should be OK with the original code from the instructable.
Song of the Day: The Grand Illusion
Creating an optical illusion with tech is pretty cool. It made this song from Styx come to mind:
Bonus Song: A Kind of Magic
Speaking of illusion and magic: