design document for THEREMIN submitted to: Professor Joseph Picone ECE 4522: Senior Design II Department of Electrical and Computer Engineering Mississippi State University Mississippi State, Mississippi 39762 May 1, 2001 submitted by: D. Beard, M. Caudle, W. Koay, J. Wong Faculty Advisor: Dr. Ray Winton Department of Electrical and Computer Engineering Mississippi State University Box 9571 Mississippi State, Mississippi 39762 Tel: 662-320-4552 email: [email protected], [email protected], [email protected], [email protected] ECE 4522 May 1, 2001 EXECUTIVE SUMMARY The theremin emerged around the year 1920 and was named after its inventor Leon Theremin. The theremin has evolved since then and although it still remains a mysterious instrument to the public, its musical potential is well recognized by electronic music enthusiasts. The theremin is built on the concept of variable capacitance. Two antennas, one controlling pitch and one volume, are mounted on the top and side of the instrument. Pitch is changed by the proximity of the thereminist’s right hand to the top antenna [1], which varies the frequency of one radio frequency (r.f.) oscillator, creating an audible beat frequency with respect to a fixed oscillator. The volume control circuit with added hand capacitance affects a third r.f. oscillator that varies a DC voltage to control the gain of a voltage controlled amplifier. Although the theremin is a unique and useful instrument, various design characteristics limit its playability. The antenna style volume control is also the performer’s only means to awkwardly articulate notes. Playing a short pitch with a precise beginning and end is virtually impossible. Also, free movement of the hand around the pitch antenna makes playing in tune extremely difficult. Pitch control of the theremin has always been a problem in its design. The theremin has a very sensitive pitch control that must be designed carefully [4]. Also, the power source of the theremin will greatly influence its performance and stability. Thus the construction of the theremin will also involve choosing a suitable power source, which will minimize disturbance to the oscillators. Scarcity of the instrument has handicapped its development in the musical arena. Thus, another focus of the design will be in reducing the cost of construction to make the theremin better suited for mass production. The theremin pitch control has many influencing factors, including proximity of other capacitive elements as well as the type of power source used. Packaging and cost of parts will also play an important role in the production of the theremin. Although there are size constraints, such as the distance between the antennas cannot be less than eighteen inches, the design will focus on reducing the size of the instrument and thus making it more portable. Meeting these design requirements will open a great door towards the theremin’s role in the music industry. Users will benefit from a more readily available, portable and playable theremin. Future development in electronics will lead to further improvement of the overall design of the theremin. Also, a digital theremin that produces a distinct note would offer another alternative providing greater musical expression (employment of legato and staccato playing style) and making the theremin more playable to less skillful musicians. Digital effects would also add to the dynamics of the sound, allowing therminists to explore endless combinations of effects for their music.Theremin ECE 4522 May 1, 2001 Table of Contents ABSTRACT…………………………………………………. 1 1. INTRODUCTION……………………………………………. 1 2. PROBLEM…………………………………………………… 1 3. OBJECTIVES……………………………………………….. 2 4. APPROACH…………………………………………………. 4 4.1 Pitch Circuit…………………………………………. 5 4.2 Switchable Discrete Mode.……….……………. 7 4.3 Cost……………..………………………………….. 11 4.4 Physical Attributes………………………………….. 12 4.5 Volume Circuit…………………………………….… 12 4.6 Tuner Out Circuit…………………………………… 14 4.7 Foot Switch………………………………………….. 15 4.8 Power Supply………………………….……………. 16 5. TEST SPECIFICATION…………………………………….. 17 6. TEST RESOURCES………………………………………… 20 7. SIMULATION TEST CERTIFICATION……...…………….. 21 8. HARDWARE TEST VERIFICATION……………………….. 31 9. SUMMARY……………………………………………………. 36 10. FUTURE WORK……………………………………………… 37 11. ACKNOWLEDGEMENTS…………………………………… 38 12. INDIVIDUAL CONTRIBUTIONS……………………………… 38 13. REFERENCES…………………………………….………….. 40Theremin ECE 4522 May 1, 2001 APPENDIX………………………………………………….. 42Theremin Page 1 of 49 ECE 4522 May 1, 2001 ABSTRACT The theremin is an unusual musical instrument with an interesting past. For various reasons, many of the electronic instruments that were inspired by the theremin have gone on to surpass it in popularity. Some of the factors the serve to limit the application of the theremin include: a difficult to control continuous pitch range, a continuous volume control that prevents staccato playing and the lack of any physical reference point for producing desired notes. The goal of this project is to provide solutions to the above problems in order to make the theremin a more practical, approachable and useful instrument for amateur and skilled musicians alike.
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