Transcript Theremillusion - College of Engineering | UMass Amherst

Theremillusion
Imen Ben Neticha
Snigdha Jonna
Sandra Jenkins
Steven Bennett
Advisor: Professor Siqueira
University of Massachusetts Amherst
Team Members
Steven Bennett
CSE
Snigdha Jonna
EE
Imen Ben Neticha
EE
Sandra Jenkins
EE
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Background
Invented by Léon Theremin in 1920
Originally got the idea
while working on short
wave ratio equipment
and capacitive sensing
during the Civil War in
Russia
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Theremins in Real Life
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Popular in Hollywood
Used in the 1966 popular
Beach Boys song “Good
Vibrations”
Kits widely used by
electronics enthusiasts
Used in The Outer limits
TV show among others
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How Does it Work
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Schematic for analog Theremin
Will modify the schematic as we build
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Motivation
 You don’t need to touch anything
− Magical aspect
 Wanted to learn how to play
− Pick up music knowledge
 Electrical Engineering Base
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Problems with Theremin
 No Reference
 Continuous Pitch and volume
 Theremin uses are limited
− Spooky sounds and sound effects
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Solutions for Problems
 Visual Reference:
− Optical Fibers for hand
positions
− Feedback on note accuracy
 Create discrete playing
mode
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Visual Component
Optical Fibers for strings of harp
− Don’t effect electromagnet field
− Don’t take up that much space
− Edge Emitting fibers
− Inexpensive
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What will the Program Do?
 Teaching (guide user to play a song)
 Note accuracy (show how close the
sound produced by user is to the target
note)
− Score shown with how many of the strings
light up at the end of a song.
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Visual Component Block Diagram
Note file
PIC32 Microcontroller
LED
Illuminators
Optical
Fibers
See handout for more details
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Why PIC32MX7XX?
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Analog Features
Fast and Accurate 16
channel 10-bit ADC
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MCU Core
80MHz, 1.56
DMIPS/MHz, 32-bit
MIPS M4K® Core
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Programmable
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MPLAB C Compiler for PIC32 MCUs!
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PIC32 DSP Library
Applicable to audio, video and other
multimedia applications.
mips_fft16 - Compute the complex FFT of a
vector containing Q15 complex samples,
i.e., 16-bit fractional real and imaginary
parts.
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Challenges
Building the Theremin
● Learning Music
●
Lack of music background for team members
● Need to work with professors in Music Dept.
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Visual component and Optical Fibers
Difficult to cut
● Make sure that they are edge-illuminated
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Theremin Teaching:
Music Storage and song generation
● Different people changing sound differently
●
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Modular Design
Software
Traditional Theremin
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Timeline
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Responsibilities
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Imen
−
Fiber Optics and LED Circuitry
−
Discrete Circuitry (Frequency to voltage and
vice versa)
−
Output Control
Sandy
−
Pitch Circuitry
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Discrete Circuitry (voltage comparison)
Snigdha
−
Volume Circuitry
−
Discrete Circuitry (voltage comparison)
Steven
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Teaching mode programming
−
Displaying note accuracy programming
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Preliminary Costs
Part
Inductors
Microcontroller (PIC32)
Resistors/Capacitors
Pitch Antenna
Transistors
Volume Antenna (knob?)
Diodes
LM13700 (Amplifer)
Voltage Regulator
Quantity
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1
81
1
8
1
5
1
2
Cost
$20.00
$40.00
$3.66
$2.00
$0.72
$0.30
$0.10
$0.53
$2.30
LM331 (V to Freq converter)
2
$3.02
PIC16F870 (A to D converter)
1
$2.74
1
200ft
40
1
1
$0.25
$20.00
$20.00
$20.00
$10.00
$145.62
$200.00
LM239 (Voltage Comarator)
Fiber Optic Cable
LEDs
Plastic Rod for Structure
Box
Total
Total with Shipping
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SDP Day
 Working Theremillusion will
look like a harp, but will
sound like a theremin.
 The fiber optic cables will
light up to teach the use how
to play the theremin.
Fiber optic cables
Pitch
Antenna
Theremin and
Microcontroller
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END
 Thank You!!!
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References
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Kenneth D. Skeldon, et al. Physics of the Theremin. Department of Physics and Astronomy,
University of Glasgow, Glasgow G12 8QQ, Scotland. Received 15 May 1998; accepted 12 June
1998.

Way, Beng Koay; Douglas Beard, Micah Caudle, and Jeffrey Jun-Fey Wong. Theremin.
Department of Electrical and Computer Engineering at Mississippi State University.
<http://www.ece.msstate.edu/courses/ece4522/projects/2001_spring/theremin/>.
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Holloway, Barry. Theremin. Strange Apparatus. 2009-2011.
<http://www.strangeapparatus.com/Theremin.html>.
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Sparkfun Electronics. “USB 32-bit Whacker – PIC32MX795 Development
Board”.<http://www.sparkfun.com/products/9713>.
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Physics of Theremin
 Antennas
 Difference between Analog/digital
theremins
 Physics of the variable capacitance and
how that changes the oscillators (how
oscillators change sound)
 Sandy email about finding theremin
player
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Powering the theremin
 Theremin can be powered by 12 volts.
 This can be done by building a stepdown transformer that will convert the
normal house voltage or buy a power
cord with a built in converter.
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Design Requirements
 Visual Display
− Will display current note being played and if in teaching
mode, indicate how close the note is to target note.
 Visual Reference (Fiber Optics)
− Lights will indicate the general location the hand has to
be in to play a particular note.
− (tentative) A light will change color depending on how
close or far away the sound is from the target note.
 Continuous and Discrete Playing Mode
− Device will be able to be switched between playing in
the traditional continuous range and playing only
discrete notes in specific frequency ranges.
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Modular Design
Frequency
to Voltage
Mixer/
Detector
Variable
Oscillator
Voltage to
Frequency
Voltage
Comparison/Discrete
Output
Output Processing
Switch
Optical
Fibers
Display
Fixed
Oscillator
Visual
Interface
Pitch Control
VCA
Variable
Oscillator
Knob
Volume
Tuning
Volume
Control
Audio
Amplifier
Output control
Learning
Mode
Tuning
Software
Interface
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FFT Complexity
Radix 2
Multiplies
FFT length (real)
1024
10248
Adds(real)
30728
Mults + Adds
40976
Split Radix
1024
7172
27652
34824
Prime Factor Alg 1008
5804
29100
34904
Winograd FT Alg 1008
3548
34416
37964
TABLE 1: Representative FFT Operation Counts
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