Created by Saboo, Pranav, last modified by Harikrishnan, Rahul on Sep 27, 2019

Rahul Harikrishnan, rahulh2, ECE 110 / Pranav Saboo, psaboo2, ECE 120

  1. Introduction
    1. Statement of Purpose: Our objective is to apply circuit concepts learned in ECE courses to construct a theremin. Essentially, a theremin is an electronic musical instrument that can be played without physical contact.
    2. Background Research:
      i. What made us choose this project?
      In high school, Rahul spent time in Science Olympiad designing and building a violin. This project was completed, but it was a low quality violin and expensive machinery like laser cutters and 3D printers were required in the building process. We decided we wanted to build another instrument and with some research found the theremin. The idea of making one appealed to us because it required less use of machinery in the manufacturing process, and rather could be assembled entirely on a breadboard. This also means that, upon completion, we will have made a DIY tutorial that can be followed by other people looking to make an affordable instrument.
      ii. How did we research our project?
      We searched online to ensure the project was feasible. A readily-made theremin costs $250+ to make, and theremin kits are around $150. We found multiple articles and videos outlining the process of building a theremin, and the costs of each of these were far cheaper than these kits. Youtube users GreatScott! and Keystone Science have video tutorials for building theremins, and we assembled our parts list through them. For this process, we took into consideration the differences of each theremin and chose the parts that we thought could create a theremin that improves upon each of their projects instead of following them directly. As such, we will be referring to each video if we come across issues in the future.


  2. Design Details
          a.  Block Diagram/Circuit Schematic

    b.  System Overview: The main concepts that affect how the theremin works are resonant frequency and capacitance, which are also the main themes in the circuit schematic above. Resonant frequency the natural oscillation frequency of an LC (inductor and capacitor) circuit, seen twice in the schematic. The back-and-forth current between the inductor and the capacitor is a vital component of the theremin. Capacitors in general are also crucial to the functioning of the theremin due to their ability to store energy and release it quickly, similar to a temporary battery. The 9V batteries drive the current that powers the circuit, and the antenna is what allows different pitches to be played.


  3. Parts

    • 2 x 9V Battery

    • 2 x 100 Ohm Resistor

    • 3 x 10 microfarad capacitor

    • 2 x 1 mH Inductor

    • 1 x 470 Ohm Resistor

    • 1 x 150 pF capacitor

    • 1 x 130 pF capacitor

    • 3 x 1.5 nF capacitor

    • 2 x 3.3 pf capacitor

    • 1 x 2.2 kilo-ohm resistor

    • 2 x 8.2 kilo-ohm resistor

    • 3 x JFET transistor

    • 4-50 pF variable capacitor

    • 2 x breadboard

    • Wires (like the ones in the ECE 110 kit)

    • 2 x 9V Battery Clip Connector

    • 6mm telescopic antenna


    4.  Possible Challenges: Potential challenges our group could encounter while building the theremin would most likely stem from the complexity of the circuit we have to build. Improper circuit analysis could lead to simple issues such as shorting the battery or more complicated problems related to the type of capacitors and inductors that we will use for this project. Since both of us are relatively inexperienced at troubleshooting and debugging circuits with these elements, we will likely need to spend more time than anticipated to complete the project. Hence, some modifications including new material purchases might need to be made as we encounter problems that we did not foresee. However, since all of the materials we are using are economical, this should not be a large issue.


   5.  References:

[1]"14.5: Oscillations in an LC Circuit", Physics LibreTexts, 2019. [Online]. Available: https://phys.libretexts.org/Bookshelves/University_Physics/Book%3A_University_Physics_(OpenStax)/Map%3A_University_Physics_II_-_Thermodynamics%2C_Electricity%2C_and_Magnetism_(OpenStax)/14%3A_Inductance/14.5%3A_Oscillations_in_an_LC_Circuit. [Accessed: 27- Sep- 2019].

[2]"60.17 -- Theremin", UCSB, 2019. [Online]. Available: http://web.physics.ucsb.edu/~lecturedemonstrations/Composer/Pages/60.17.html. [Accessed: 27- Sep- 2019].

[3]"How to make a Theremin", YouTube, 2019. [Online]. Available: https://www.youtube.com/watch?v=oRhO0MJIl58. [Accessed: 27- Sep- 2019].

[4]"LC Circuits", University of Texas, 2019. [Online]. Available: http://farside.ph.utexas.edu/teaching/315/Waves/node5.html. [Accessed: 27- Sep- 2019].

[5]"Make your own Simple Theremin", YouTube, 2019. [Online]. Available: https://www.youtube.com/watch?v=_FytVf5hH88. [Accessed: 27- Sep- 2019].

[6]"My New Year gift to TW: A new theremin circuit", Theremin World, 2019. [Online]. Available: http://thereminworld.com/Forums/T/29231/my-new-year-gift-to-tw. [Accessed: 27- Sep- 2019].

[7]R. Moog, "Build the EM Theremin", EMTheremin, 2019. [Online]. Available: https://www.cs.nmsu.edu/~rth/EMTheremin.pdf. [Accessed: 27- Sep- 2019].




Comments:

I'm glad that you have a circuit that you are working off of! I recommend prototyping on a breadboard as early as possible, as you'll probably find the circuit doesn't work quite the way you expect. We should be able to get most of the capacitors and resistors from the service center (as a TA during lab)
Posted by chorn4 at Oct 03, 2019 12:40

Looks great. Glad you guys have EAGLE experience.
Posted by fns2 at Oct 03, 2019 18:45