University of Massachusetts Amherst Theremillusion The Thereminators: Imen Ben Neticha Snigdha Jonna Sandra Jenkins Steven Bennett Advisor: Professor Siqueira

University of Massachusetts Amherst

Theremillusion

The Thereminators: Imen Ben NetichaSnigdha JonnaSandra JenkinsSteven Bennett

Advisor: Professor Siqueira

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Grenzebach Glier & Associates, Inc.

Team Members

Snigdha JonnaEE

Steven BennettCSE

Imen Ben NetichaEE

Sandra JenkinsEE

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Responsibilities – Reallocations

Imen

− EL Wires and EL Sequencer

− Visual Output Control

Sandy

− Theremin Integration and Troubleshooting

− Discrete Mode (digital to voltage)

Snigdha

− Theremin Troubleshooting

− Discrete Mode (voltage to frequency)

Steven

− Displaying note accuracy programming

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Invented by Léon Theremin in 1920

Background

Originally got the idea while working on short wave ratio equipment and capacitive sensing during the Civil War in Russia

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Motivations for Theremin Modification

No Reference

Continuous Pitch and volume

Need to have extensive ear training

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How Does it Work

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Theremin Principles

Beat Frequency Oscillators

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Wire Wrapping the Theremin

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Theremin Kit Theremax Theremin

− Volume and Pitch Antennas

− Volume and Pitch field adjustment knobs

− Timbre control: useful for external signal processing (aka Discrete Mode)

− Manual for general operation and tuning

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Discrete Mode-Theremin

SWITCHAnalog-to-Digital Converter in a PIC Controller

Digital-to-Analog Converter

Voltage to Frequency Converter

SPEAKERS

Frequency from the Theremin

Discrete Signal Processing in MicroController

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Analog to Digital Converter in PIC

The Microcontroller PIC32 has a 10-bit Analog-Digital- Converter in it.

PIC32 has a range of 0 to 5.5V input voltage.

The PIC takes in frequency and converts it into a binary number.

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Software in PIC32

The Analog-to-Digital converter displays the frequencies that it reads from the Theremin.

These frequency values are grouped together to output a specific frequency based on a frequency-to-note conversion table.

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Conversion table Calculation for Equal-Tempered tuning [A4 = 440Hz]

Hertz Octave=1 Octave=2 Octave=3 Octave=4 Octave=5 Octave=6

0 A 55.000 110.000 220.000 440.000 880.000 1,760.000

1 A#/Bb 58.270 116.541 233.082 466.164 932.328 1,864.655

2 B 61.735 123.471 246.942 493.883 987.767 1,975.533

3 C 65.406 130.813 261.626 523.251 1,046.502 2,093.005

4 C#/Db 69.296 138.591 277.183 554.365 1,108.731 2,217.461

5 D 73.416 146.832 293.665 587.330 1,174.659 2,349.318

6 D#/Eb 77.782 155.563 311.127 622.254 1,244.508 2,489.016

7 E 82.407 164.814 329.628 659.255 1,318.510 2,637.020

8 F 87.307 174.614 349.228 698.456 1,396.913 2,793.826

9 F#/Gb 92.499 184.997 369.994 739.989 1,479.978 2,959.955

10 G 97.999 195.998 391.995 783.991 1,567.982 3,135.963

11 G#/Ab 103.826 207.652 415.305 830.609 1,661.219 3,322.438

12 A 110.000 220.000 440.000 880.000 1,760.000 3,520.000

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Digital to Frequency Conversion

DAC5675A chip: D/A converter

LM331 Voltage-to-Frequency Converter The equation that

relates the frequency

to voltage:

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PIC32 DSP

16 Channel 10-Bit ADC

80 MHz, 1.56 DMIPS/MHz, 32-Bit M4K Core

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FFT Demonstration

Configure IO Registers

Allocate and Prepare buffers.

256 Samples of Analog Signal at 10 KHz

Call Microchip Library Fuction:mips_fft16(dout, calcbuffer, fftc, scratch, log2N)

Meaningful Results: Magnitude/Frequency

Transmit Blocks of Data to USB

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What’s Next

Analog Audio can be compared to a Musical Note Lookup Table

Derive a Score fromPlayed Note vs Expected Note

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Results

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Why the EL Sequencer● Easy to use, no need to re-invent the wheel

● Relatively inexpensive for the amount of hardware (in comparison to building one from scratch)

● Incorporates programming into the software

● Using a microwave transformer is more labor, more bulky, and not as accurate (results)

● Safer. EL wire is 100+V at 4000hz, but very low power. Instead of a shock, you will feel a small tingle if touched in the wrong places

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EL Sequencer

● Board can be powered from USB or LiPo

● Switch chooses source and acts as on/off

● Compatible with Arduino (8MHz LilyPad)

● On-board 8MHz external resonator

● 8 TRIACs can handle up to 600V

● Control 8 channels of EL

● Runs on 3.7V LiPo

● Footprint for connection to FTDI Basic for downloading code

● Footprint for connection to Nordic nRF24L01 2.4GHz wireless module

ATmega328 based control board that allows the user to program any sequence of blink, on/off, even pulse width modulation (PWM) pulsing of EL wire

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TRIACs in the EL Sequencer

● While EL wire requires very little power, you can't use normal transistors to turn on/off a string of it

● So we use TRIACs → nifty 'switches' that allow you to turn on/off an AC source

● Triode for Alternating Current

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Integration with PIC32

● The EL Sequencer will guide the user with a series of lights.

● three levels (easy/medium/hard)

● PIC32 will compare and grade the user

● PIC32 interfaces with EL sequencer to display score on the EL wires

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Timeline

Feb 24th – Finish Theremin Assembly

March 2nd – Finish integrating PIC32 FFT and EL Sequencer for light control

March 9th – Finish integrating PIC32 and discrete mode

March 16th – Finishing integrating parts

March 23rd – Week for trouble shooting

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SDP Day

Working Theremillusion will look similar to a harp.

Glow Wires

The glow wires will light up to teach the use how to play the theremin.

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END

Thank You!!!

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References 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/>.

Holloway, Barry. Theremin. Strange Apparatus. 2009-2011. <http://www.strangeapparatus.com/Theremin.html>.

Sparkfun Electronics. “USB 32-bit Whacker – PIC32MX795 Development Board”.<http://www.sparkfun.com/products/9713>.

PAiA, “Theremax FAQ.” <http://www.paia.com/ProdArticles/therefaq.htm>.

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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 step-down 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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Software Interface

Modular Design

Visual Interface

Optical Fibers

Display

Output Processing

Frequency to Voltage

Tuning

Learning Mode

Output control

VCA

Audio Amplifier

Pitch Control

Variable Oscillator

FixedOscillator

Mixer/ Detector

Volume Control

Variable Oscillator

Knob

Volume Tuning

Voltage to Frequency

Voltage Comparison/Discrete

Output

Switch

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FFT Complexity

FFT lengthMultiplies (real) Adds(real) Mults + Adds

Radix 2 1024 10248 30728 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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Reasons for the Theremin Kit

Building the Theremi

Comparable to creating an acoustic guitar for a woodworker

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Documents

University of Massachusetts Amherst Theremillusion The Thereminators: Imen Ben Neticha Snigdha Jonna Sandra Jenkins Steven Bennett Advisor: Professor Siqueira