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Fibonacci256 is a beautiful 166mm circular disc with 256 RGB LEDs surface mounted in a Fibonacci distrubution. Swirling and pulsing like a colorful galaxy, it’s mesmerizing to watch.
It consists of 256 RGB LEDs, arranged into a circular Fermat’s spiral pattern.
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In disc phyllotaxis, as in the sunflower and daisy, the mesh of spirals occurs in Fibonacci numbers because divergence (angle of succession in a single spiral arrangement) approaches the golden ratio. The shape of the spirals depends on the growth of the elements generated sequentially. In mature-disc phyllotaxis, when all the elements are the same size, the shape of the spirals is that of Fermat spirals—ideally. That is because Fermat's spiral traverses equal annuli in equal turns. The full model proposed by H Vogel in 1979 is
where θ is the angle, r is the radius or distance from the center, and n is the index number of the floret and c is a constant scaling factor. The angle 137.508° is the golden angle which is approximated by ratios of Fibonacci numbers.
Fermat's spiral. (2015, October 24). In Wikipedia, The Free Encyclopedia. Retrieved 02:45, February 24, 2016, from https://en.wikipedia.org/w/index.php?title=Fermat%27s_spiral
- Size: 6.54 x 6.54 x .063 inch (166 x 166 x 1.6 mm)
- 2 layer printed circuit board
- FR4 substrate
- Green SMOBC (solder mask over bare copper)
- HASL (Hot Air Solder Leveling) Finish
- Designed in the USA
Includes only the printed circuit board with LEDs, does not include parts that are required to assemble and run it (microcontroller, power supply, wires, etc).
Parts that are not included, but are required to assemble and use:
- Microcontroller (Arduino, ESP8266, ESP32, etc):
- Power supply, or run off of USB power from microcontroller.
- Wires, connectors, crimp tool, etc.
- Soldering iron, solder, etc.
Parts I used in my builds (also not included):
Open source example firmware and web application: https://github.com/jasoncoon/esp8266-fastled-webserver/tree/fibonacci256
3D Printed Case
3D printed case with 3mm black LED acrylic diffuser (work in progress): https://www.thingiverse.com/thing:4191326
Note: Double-check the position, alignment, and orientation of each component very carefully before soldering!
If you’re new to soldering, I highly recommend reading through a good soldering tutorial, such as the ones by Adafruit and SparkFun.
- Find a clean spot on your soldering workspace. I used a piece of heavy card stock. Carefully place the board with the LEDs facing down and the bottom of the board facing up.
- I used 90 degree header pins to allow connecting and disconnecting jumper wires easily. I used small female headers to keep them level while I soldered.
- Insert the header pins.
- Carefully turn the board over and solder only the middle pin of each header.
- Ensure the headers are straight and level before proceeding to solder the remaining pins. The 5V and GND pins are connected to planes with large traces, and may take some time to heat up enough for solder to melt. Using a higher temperature and less time can help, if possible. Flux can also help.
- Check each solder joint, then disconnect the female headers.
- VERY carefully check polarity before connecting 5V and GND. If possible, connect 5V and GND on both sets of headers to provide maximum current flow and minimize voltage drop. I used female jumper wires.
- Connect the data pin from your microcontroller to the DI pin on the Fibonacci board.
- Each WS2812 can theoretically draw 60mA at full brightness, solid white color. 256 of them can theoretically draw 15.36 Amps! I strongly suggest using FastLED’s power management to limit the maximum brightness to a reasonable amount, well under the maximum your power supply is rated for. I’ve found even just 2A from a USB power adapter is blindingly bright.
- Keep an eye on the temperature of the PCB and especially the connectors. High temperatures can reduce the life of the LEDs. When possible, ensure air can flow, either passively (ventilation) or actively (exhaust fan).
- Most header pins are rated for 4-6 amps, but be sure to check your pins and wires. High temperatures increase resistance, which increases temperature, ad infinitum. If temperatures exceed the maximum rating of the wire insulation, sparks and fire can occur at high amperage.