LED Infinity Table
Abstract
The goal of this project was to integrate all electronic aspects of a LED Infinity Table into a modular printed wiring board. Project design goals consisted of integrating 480 individually controlled WS2811 LEDs with a microphone system for brightness and color phase modulation. The system was created to easily disconnect from the table for programing and maintenance.
Project Description
The LED infinity Table consists of a table assembly that houses a mirror facing upwards and a one-way mirror facing downwards. LEDs are positioned around the interior of the table frame between the two mirrors. A portion of the light escapes every time it is internally reflected creating an effect where the single LED strip appears to be a wall of LEDs reflected to infinity, hence the name “Infinity Table”. WS2811 LED strips were chosen because they are individually controllable and feature 60 LEDs per strip. These LEDs signal and power lines run at 5V. A Teensy Microcontroller (U3) was chosen because of the high quality components for the price. The Microcontroller is 64 times more powerful than an Arduino UNO and could support the quantity of LEDs involved in this project. Using FFT, a MEMS microphone (U5) with a built in amplifier allows for brightness modulation based on audio frequency. A digital potentiometer (U6)(MAX5450) in conjunction with a jumper (J1) allowed for tuning of the gain for the microphone (U5). An anti aliasing filter consisting of a 4nF capacitor was added after the boards fabrication to limit noise and aliasing effects on the microphone (U5). Two Ethernet female connectors (U2 and U4) were integrated to the board to allow for data output to 8 LED strips while sourcing 5V. A voltage translator (U1) converts the Teensy data output at 3.3 V to the 5V signal specified in the LED datasheet. A bidirectional TVS avalanche diode (D1) was used to protect the Teensy from any possible surges. A Photo of the board layout and schematic are included in the appendix below.
How it Works
A signal is sent from 8 pins on the microcontroller to the voltage translator (U1) then to the Ethernet (U2 and U4) female connectors (four signal wires each). The 480 LEDs were cut into 8 equal strips, one for each signal. Power is supplied to these strips from a computer power supply. The remaining pins for the Ethernet plugs (U2 and U4) were tied together as power and ground. This provide power from an external power supply to the Teensy (U3) while keeping the high current the table draws as a separate connection. Audio is received through a MEMs microphone (U5) and internally amplified. The gain is adjustable through the use of a digital potentiometer. From the microphone (U5) and digital potentiometer (U6) the microphone signal is passed to the Teensy (U3) and a FFT is used to convert the signal into 256 bins based on frequency. The frequency bins are tied to specific colors for color phase modulation of the table. To eliminate aliasing effects and noise a 4.4nF capacitor was placed from the microphone signal to ground.
Conclusions and Discussion
Through this class I have achieved a goal I have been chasing my entire college career. I designed and built a professional product that I am debating selling online as a kit. My circuit board (despite some necessary rework) performed flawlessly and I am excited to continue my learning process by learning to code further in C with this device. I learned a great deal from this class and I really appreciated the freedom to pursue my own project. I learned about coding, microcontrollers, circuitry and most importantly designing a circuit board. I feel like I will retain what I have learned and will be able to apply these skills in hobbies as well as my career. My experience really drove home how interconnected and interdisciplinary all aspects of a manufacturing process are!
Downloads
- BOM (PDF)
- Schematics (PDF)
- Layouts (PDF)