frequency beats: final report 8 april 2014
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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Frequency Beats:Final Report8 April 2014
Team Couch Street Alex Arlint Jake Nylund Kevin Ratuiste Robert Rodriguez
Academic Advisor: Joseph HoffbeckIndustry Representative: John Turner – Impinj, Inc.Client: William Taylor - Student
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Introduction What Is it? Control Circuit Electromagnets Display Software Demonstration Conclusion
Overview
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Frequency Beats◦ Audio Visualizer
Low, Mid, High frequencies◦ Utilizes Ferrofluid
What is it?
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Circuit SchematicElectromagnet(Low-Range)
Electromagnet(Mid-Range)
Electromagnet(High-Range)
Arduino
12V
100ё
33uF
Low-Range Out
100ёMid-Range Out
100ё
33uF
High-Range Out 33uF
Audio Input
Powered Speaker
LPF
LPF
LPF
11
1213
BAT42 BAT42 BAT42
2N3904IRF3205
3.3V
10kё
10kё
2N3904IRF3205
10kё
10kё
1
2
3
1
2
3
1
2
3
1
2
3
2N3904
IRF3205
10kё
10kё
1
2
3 1
2
34.7kё
4.7kё
4.7kё
3.3kё
2.7kё
100uF 1kё
1kё
Audio Source
3.3V
Vcc
NC
NC
NC
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From Arduino
Electromagnet
100ё
33uF
LPF
BAT42
2N3904IRF3205
10kё
10kё
1
2
3 1
2
34.7kё
3.3kё
2.7kё
12V3.3V (From Arduino)
NC
Control Circuit
HIGH
ON
PulledUp
LOW PulledDown
OFF
Ve > Vb
Ve < Vb
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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)
Electromagnets
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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)
Electromagnets (Cont.)
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Electromagnets (Cont.)
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Electromagnets (Cont.)
LatheHand-Wrapped
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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.
Display
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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.
Display (Cont.)
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Display (Cont.)
Homemade Ferrofluid
Purchased Ferrofluid in Plexiglass
Purchased Ferrofluid in Glass Container
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Electromagnet + Display
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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
Software/Arduino
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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
Software – cont.
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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
Arduino Programming
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Fourier Transform: transform signals between time and frequency.
Measure amplitude & frequency of audio input
http://en.wikipedia.org/wiki/Fast_Fourier_transform
FFT – Cooley-Tukey
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Sampling
Audio Input
- Input signal - Samples The samples are
gathered by measuring the voltage on the Arduino.
We take 512 samples
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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
Using the output
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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
The PWM
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Switches Individual frequencies Music
Demonstration!
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Introduction What Is It? Control Circuit Electromagnets Display Software Demonstration Conclusion
Conclusion
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QUESTIONS?