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Frequency Beats: Final Report 8 April 2014

Frequency Beats: Final Report 8 April 2014. Academic Advisor: Joseph Hoffbeck Industry Representative: John Turner – Impinj , Inc. Client: William Taylor - Student. Team Couch Street Alex Arlint Jake Nylund Kevin Ratuiste Robert Rodriguez. Overview. Introduction

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Frequency Beats: Final Report 8 April 2014

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  1. Frequency Beats:Final Report8 April 2014 Academic Advisor: Joseph Hoffbeck Industry Representative: John Turner – Impinj, Inc. Client:William Taylor - Student Team Couch Street Alex Arlint Jake Nylund Kevin Ratuiste Robert Rodriguez

  2. Overview • Introduction • What Is it? • Control Circuit • Electromagnets • Display • Software • Demonstration • Conclusion

  3. What is it? • Frequency Beats • Audio Visualizer • Low, Mid, High frequencies • Utilizes Ferrofluid

  4. Circuit Schematic

  5. Control Circuit ON OFF Ve> Vb Pulled Up HIGH LOW Pulled Down Ve < Vb

  6. Electromagnets • Initial Design Plan • 110 feet of 22 gauge magnet wire around .5” diameter metal core 5” in length. • Would provide internal resistance of 1.77Ω. • Hand wrapped • Final Design • Approx. 270 feet of 26 gauge magnet wire around 0.25” diameter iron core 5” in length. • Provided internal resistance of ~13Ω. • Wrapped using a Lathe. • Kept coils tight and close together. • Slow process (2+ hours per magnet)

  7. Electromagnets (Cont.) • Reasons for Design Change • Increased length necessary to attain stronger magnetic field. • Diameter of core change selected based on availability. • Lathe vs. Hand-Wrapping Magnets • Lathe was a vastly slower process, but ultimately yielded a superior product (as seen on the next slide)

  8. Electromagnets (Cont.)

  9. Electromagnets (Cont.) Hand-Wrapped Lathe

  10. Display • Initial Design Plan • Plexiglass cylinders with 2” diameter and 5” height. • Filled with “homemade” ferrofluid. • Toner mixed with vegetable oil. • Final Design • Glass cylinders with 1” diameter and 2.5” height. • Filled with ferrofluid (Ordered online) and encased in water for better reactivity.

  11. Display (Cont.) • Reasons for Design Change • Homemade ferrofluid was unforeseeably difficult to manufacture • Consistency not correct. • Not reactive enough to magnetic field. • Plexiglass seemed to allow the ferrofluid to stick to the sides, thus “mucking” up the display.

  12. Display (Cont.) Purchased Ferrofluid in Plexiglass Purchased Ferrofluid in Glass Container Homemade Ferrofluid

  13. Electromagnet + Display

  14. Software/Arduino • Initial Design Plan: • Fast Fourier Transform algorithm • Quickly sample audio signal • Compute amplitude of each frequency in audio signal • Problems with the Arduino Due • Contingency Plan: • MSGEQ7 IC – does frequency analysis of audio signal and outputs 7 bands • Arduino combines bands and scales values

  15. Software – cont. • Final Design • Same as initial design plan • Took weeks to troubleshoot • Adapted customized library to be compatible with IDE instead of using premade libraries • Used sample implementations of FFT and other source codes as a model for custom library

  16. Arduino Programming • Init() • sampleLoop() • Continuously sample the analog audio input • Perform FFT, producing real and imaginary parts for each frequency bin • Take magnitude of each frequency bin • Combine magnitudes into three frequency bands • 80Hz-255Hz, 255Hz-6kHz, 6kHz-12.5kHz • Select highest magnitude from each band • Output to LPF as a PWM signal to smoothed into a DC signal for control circuit • Repeat

  17. FFT – Cooley-Tukey • Fourier Transform: transform signals between time and frequency. • Measure amplitude & frequency of audio input http://en.wikipedia.org/wiki/Fast_Fourier_transform

  18. Sampling • - Input signal • - Samples • The samples are gathered by measuring the voltage on the Arduino. • We take 512samples Audio Input

  19. Using the output • Output array of 256 samples or bins • The FFT gives half of the input • Each bin is approximately an 85Hz sample range • Bin 1 would be 85-170Hz roughly • Bin 0 is a reference bin and causes some noise for our calculations

  20. The PWM • Each value initially calculated by the FFT is scaled to a value between 0 and 255 • 63-> • 127-> • 191-> http://arduino.cc/en/Tutorial/PWM

  21. Demonstration! • Switches • Individual frequencies • Music

  22. Conclusion • Introduction • What Is It? • Control Circuit • Electromagnets • Display • Software • Demonstration • Conclusion

  23. QUESTIONS?

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