ECE 110/120 Honors Lab Section : MIDI Controlled Theremin

Final Results

Final report: https://docs.google.com/document/d/1Rd3qXO9wnfgkCMLPzmiEysDYktcKXa02gnQwIq-JRko/edit?usp=sharing

Demo video: https://www.youtube.com/watch?v=f53dRaSp69Y

Statement of Purpose

The Theremin is a beautifully underrated instrument, made entirely out of analog hardware. The method of sound production in a theremin is entirely contactless. The player varies the distance of their hands from the antennae, which results in different pitches and volumes. This is also what makes the theremin so difficult to play because maintaining the perfect distance from the antennae is extremely challenging for human players.

The sound that the theremin produces is entirely analog, as opposed to most modern digital synthesizers which produce quantized digital sounds. This gives it a really unique sound that is iconic in horror and sci-fi movies. 

We wanted to make preserve the analog sound of the theremin while making it more accessible to play. The idea of the MIDI Controlled Theremin is to create two robotic arms that can vary their lengths in order to produce music from the theremin. These arms will be controlled by servos connected to an Arduino microcontroller. The code we will write for the microcontroller would associate each musical note to a position of the servo motor.

Our goal is to create an analog theremin from scratch, as well as create the robotic arm system that can convert MIDI files to music on the theremin. 

Background Research

Although our idea is original, we found a few youtube videos that try to do similar things. One inspiration came from a youtube video that creates a MIDI slide whistle, executing a similar idea with another instrument. We also watched some youtube tutorials on how to make a DIY theremin in order to gauge the feasibility of making one from scratch.

Block Diagram / Flow Chart

System Overview

The project consists of three parts:

1. Theremin: since we plan on building a theremin from scratch, we will require the knowledge and components necessary to make the theremin's circuit. For now, the theremin is a black box to us, but we are working on how to create it from scratch.
2. Robotic Arm Hardware: next, we need to create a robotic system that emulates a theremin player's hand movements. This will interact with the theremin contactlessly.
3. Robotic Arm Software: we need to create software that can convert MIDI files to motor positions in the servo. 

Parts

(We need to do more research on the prices, however, the cost of the project seems to be well under the limit)

The parts we will require to build the theremin are:

• Plastic shell
• Pitch-reference oscillator
• Pitch-control oscillator
• Mixer
• Volume-control oscillator
• Volume-resonant circuit and voltage-controlled amplifier
• Speaker
• 12-volt power supply

The parts we will require to make the robotic arm system are:

• Servo motors: 2x
• Plastic robotic arm (or a pencil)
• Arduino microcontroller

Possible Challenges

The challenges that we could run into are:

• Buying the appropriate capacitors to represent the theremin
• Programming the Arduino to convert the MIDI input into servo movement of the pitch arm to replicate a certain note
• Building the rigid structure itself to withstand fast movements of the pitch arm
• Finding access to an electronics lab to test the components during COVID
• Making the Theremin under the price limit, as we would need to find suitable efficient replacements
• Building 3-D printable models that can house the components needed for a theremin

References

The references that we used to develop this idea are:

F. Make, "Build a Theremin under a minute," Youtube. The United States of America: Make, November 14 2008. [Video recording]. Available: https://www.youtube.com/watch?v=axrV2x-qBM8

F. Keystone, "How to make a Theremin," Youtube. The United States of America: Keystone Sciences, September 6 2017. [Video recording]. Available: https://www.youtube.com/watch?v=oRhO0MJIl58

F.Scott, "Make your own simple Theremin," Youtube. The United States of America: Great Scott!!,November 17 2017. [Video recording]. Available: https://www.youtube.com/watch?v=_FytVf5hH88