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

2 Grenzebach Glier & Associates, Inc. Team Members Snigdha Jonna EE Steven Bennett CSE Imen Ben Neticha EE Sandra Jenkins EE

3 Grenzebach Glier & Associates, Inc. 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

4 Grenzebach Glier & Associates, Inc. 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

5 Grenzebach Glier & Associates, Inc. Motivations for Theremin Modification No Reference Continuous Pitch and volume Need to have extensive ear training

6 Grenzebach Glier & Associates, Inc. How Does it Work

7 Grenzebach Glier & Associates, Inc. Theremin Principles Beat Frequency Oscillators

8 Grenzebach Glier & Associates, Inc. Wire Wrapping the Theremin

9 Grenzebach Glier & Associates, Inc. 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

10 Grenzebach Glier & Associates, Inc. Discrete Mode-Theremin SWITCH Analog-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

11 Grenzebach Glier & Associates, Inc. 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.

12 Grenzebach Glier & Associates, Inc. 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.

13 Grenzebach Glier & Associates, Inc. Conversion table Calculation for Equal-Tempered tuning [A4 = 440Hz] Hertz Octave=1 Octave=2 Octave=3 Octave=4 Octave=5 Octave=6 0 A , A#/Bb , B , C , , C#/Db , , D , , D#/Eb , , E , , F , , F#/Gb , , G , , G#/Ab , , A , ,

14 Grenzebach Glier & Associates, Inc. Digital to Frequency Conversion DAC5675A chip: D/A converter LM331 Voltage-to-Frequency Converter The equation that relates the frequency to voltage:

15 Grenzebach Glier & Associates, Inc. PIC32 DSP 16 Channel 10-Bit ADC 80 MHz, 1.56 DMIPS/MHz, 32-Bit M4K Core

16 Grenzebach Glier & Associates, Inc. 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

17 Grenzebach Glier & Associates, Inc. Whats Next Analog Audio can be compared to a Musical Note Lookup Table Derive a Score from Played Note vs Expected Note

18 Grenzebach Glier & Associates, Inc. Results

19 Grenzebach Glier & Associates, Inc. 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

20 Grenzebach Glier & Associates, Inc. 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

21 Grenzebach Glier & Associates, Inc. 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

22 Grenzebach Glier & Associates, Inc. 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

23 Grenzebach Glier & Associates, Inc. Timeline Feb 24 th – Finish Theremin Assembly March 2 nd – Finish integrating PIC32 FFT and EL Sequencer for light control March 9 th – Finish integrating PIC32 and discrete mode March 16 th – Finishing integrating parts March 23 rd – Week for trouble shooting

24 Grenzebach Glier & Associates, Inc. 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.

25 Grenzebach Glier & Associates, Inc. END Thank You!!!

26 Grenzebach Glier & Associates, Inc. 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 Way, Beng Koay; Douglas Beard, Micah Caudle, and Jeffrey Jun-Fey Wong. Theremin. Department of Electrical and Computer Engineering at Mississippi State University.. Holloway, Barry. Theremin. Strange Apparatus Sparkfun Electronics. USB 32-bit Whacker – PIC32MX795 Development Board.. PAiA, Theremax FAQ..

27 Grenzebach Glier & Associates, Inc. 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 about finding theremin player

28 Grenzebach Glier & Associates, Inc. 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.

29 Grenzebach Glier & Associates, Inc. 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.

30 Grenzebach Glier & Associates, Inc. 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 Fixed Oscillator Mixer/ Detector Volume Control Variable Oscillator Knob Volume Tuning Voltage to Frequency Voltage Comparison/Discrete Output Switch

31 Grenzebach Glier & Associates, Inc. FFT Complexity FFT length Multiplies (real)Adds(real)Mults + Adds Radix Split Radix Prime Factor Alg Winograd FT Alg TABLE 1: Representative FFT Operation Counts

32 Grenzebach Glier & Associates, Inc. Reasons for the Theremin Kit Building the Theremi Comparable to creating an acoustic guitar for a woodworker

33 Grenzebach Glier & Associates, Inc.