Visual Beats

Overview

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This project is inspired by Cymatics, the study of visualizing sound through the representation of physical mediums. The common method to visualize sound in Cymatics is by creating a frequency on a plate that vibrates a medium (such as sand or water) placed on top. The more in tune a frequency is to the plate, the more complex of a geometric shape (nodal lines) the sand creates. We initially plan on experimenting with an online frequency generator and a metal plate in order to see different kinds of standing waves we can form. Once we have found specific frequencies that resonate well with the plate, we will choose one frequency and convert it into a tone playable through a button all through the works of an Arduino. If this is successful, we will add more buttons with varying tones so that people can play around, creating their own beats in order to “see” what physical form their music takes on.

The Team

• Sudeep Raj
• Han Wang
• Li Gao

Objectives

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• Finding several resonating frequencies of the plate since stable figures are obtained the best at these frequencies
  • Reference: Chladni’s law for vibrating plates by Rossing (Page 271)
• Achieving a consistent image will depend on the distribution of sand (or silica grains) spread on the plate since the higher density nodes will be providing the form we seek.
• Having at the least 1 diametric and radial node pattern that is playable on the Arduino button.
  • The higher the count on both diametric and radial nodes, the better
• (Only if the former is successful) During the demo, anyone should be able to play with the buttons and form images on their own (although we will prepare/practice some melodies)

Challenges

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Most of the hardware we will use can be purchased, but there are still many foreseen challenges we will encounter:

• We don’t know the resonant frequencies of our specific plate are, so we will have to find them using a range of frequencies from 20Hz to 2kHz (range is considered in order to stay safe and based on an article that ran a similar experiment)
• Preventing damage to exciter/amp (clipping, overheating, etc) by making sure our physical design has some form of ventilation
• We may exceed our budget if our trials keep failing, so we need to form detailed plans on how we will run our experiments in order to prevent going over our budget
• Finding the most effective way to reuse and not waste our sand
• Assembling all our equipment in a neat and organized way for demo (for example: where we will be placing the amplifier and Arduino/circuit board as they are separate compartments to our main apparatus)
• Making sure that the least amount of manual changes have to occur when using a button to perform a design. If we are successful and end up with making more than one button then we need to find a way to make sure we don't have to toggle such things as the "Sub Volume" and "Crossover" knobs when demoing.

Budget

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• .063 Thick Aluminum Sheet (12 x 12) (Amazon) ~ $12.98
• Black Aquarium Sand 20lbs (Petco) ~ $16.39
• Exciter (58mm and 25W RMS) ~$14.80
• OSD Audio SMP60 Amp (40W RMS) ~$65.00 (USED)
• 12-Bit DAC w/I2C Interface ~ $ 4.95
• 15" by 15" by 10" Bin (Walmart) ~ $7.00

Owned

• Hot Glue Gun
• Arduino UNO
• Breadboad
• Solderless Jumper Wires
• DMM
• Banana Plugs
• Button(s)
• 12 V DC Adapter (For Arduino)
• Plywood (9" x 9")
• Salvaged PVC materials
• 16-Gauge Speaker Wire
• Audio Video RCA Cable 6ft

Est. Total

• ~$119

Schematics and Sketches

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• As for the materials of our plate, there are several materials listed on the article we found that has been proved to work well with our exciter, including aluminum. However, the frequency range that is produced is influenced by different factors(i.e. different material and exciter pairing). So there is not too much data we can refer to, but we will have to do experiments and figure out by ourselves.

• We plan on using a tub we bought from Walmart to control sand mess.

• We will connect a 12 bit DAC to the Arduino board to generate a pure frequency(click the DAC to see the detail of the exact DAC). DAC will convert digital signal (which the arduino reads) to analog signal (which the amplifier can read).

Theory/Resources/Misc

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The choices for the items under our budget are not arbitrary:

• The amplifier and subwoofer were chosen based on an article found on in the American Journal of Physics (AAPT). The article conducted an identical experiment and recommended using an amplifier that outputs at least 15 Watts and thus a sub that can handle such power
  • Article: Production of Chladni Figures on Vibrating Plates Using Continuous Excitation by Harald C. Jensen (Page 504)
• We concluded with a thickness of 0.063 for the Aluminum Sheet as as it satisfies the 6 assumptions presented in Kirchoff’s Plate Theory
  • Article: Resolving the formation of modern Chladni figures (A Letters Journal Exploring the Frontiers of Physics)
  • Text: [1] (Page 83-86)

Reproducibility of different shapes do not rely on the assembly of the setup:

• The only two factors needed to reproduce a shape found is by using the same frequency and the arbitrary boundary conditions created (Noted from Jensen's Article (Page 505))
  • We will not be experimenting with different boundary conditions and will only be using the center of the plate as the point of excitation (unfortunately, this will reduce the chances of us finding complex symmetrical patterns, but will not restrict us too far);Also, placing our exciter at the center of the plate will buildup the standing waves on the plate, so that the desired sand patterns will be more obvious.

3D/2D Graphing Using Mathematica:

• We hope to use some of the theory found in the Resolving the formation of modern Chladni figures Article to compute some nice graphs explaining how our project works in relation to Kirchoff-Love's Equation !

Gantt Chart

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Ganttchart(11.4).png