[Sean Hodgins] really harnessed the holiday spirit to create his very own Giant Spinning Holographic Christmas Tree (of Death). It’s a three-dimensional persistence-of-vision (POV) masterpiece, but as a collection of rapidly spinning metal elements, it’s potentially quite dangerous as well. As [Sean] demonstrates, the system can display other images and animations well beyond the realm of mere holiday trees.
Initial experiments focused on refining the mechanical structure, bearings, and motor. A 1/2 horsepower A.C. motor was selected and then the dimensions of the tree were “trimmed” to optimize a triangular frame that could be rotated at the necessary POV speed by the beefy motor. A six-wire electrical slip ring allows power and control signaling to be coupled to the tree through its spinning central shaft.
The RGB elements are SK9888 LEDs also know as DotStar LEDs. DotStar LEDs are series-chainable, individually-addressable RGB LEDs similar to NeoPixels. However, with around 50 times the pulse width modulation (PWM) rate, DotStars are more suitable for POV applications than NeoPixels. The LED chain is driven by a Raspberry Pi 4 single board computer using a clever system for storing image frames.
If deadly rotational velocity is not your cup of tea, consider this slower spinning RGB Christmas tree featuring a DIY slip ring. Or for more POV, may we suggest this minimalist persistence-of-vision display requiring only a few LEDs and an ATtiny CPU.
I got flashbacks of the MCP in Tron
top class film in its day
nice!
And using oled smartphone screens, it would not be better
Why not put LEDs on the second side? That would effectively double your framerate? Also adding a fly wheel to the base of the tree would help remove the air resistance from added weight with the sacrifice of spin up time.
Uh…spinning the low-inertia end?
Moments of inertia are about axes not “ends”, so having the motor at the top vs bottom has the same effect from a torque point of view.
yeah, yeah. And then we can talk about the real world issues of balance.
Same torque from the motors pov, but having the motor at the top will create much more twisting about the axes than having it at the bottom. Depending on how stiff the axle is, that could be a real consideration.
If he used 2 strips could he decrease the speed of the tree and get the same overall effect? He’s already got the other armature in place.
Why does this make me think “Doctor Who” 😃
Can it run DOOM?
https://twitter.com/idlehandsdev/status/1609614279191269379