~ICMC 2015 - Sept. 25 - Oct. 1, 2015 - CEMI, University of North Texas
Improving the Musical Expressiveness of Tesla Coils with Software
Jason Long
Victoria University of Wellington
jason.long@ecs.victoria.ac.nz
Josh Bailey
josh@vandervecken.com
James McVay
Victoria University of Wellington
jameshmcvay@me.com
Dale A. Carnegie
Victoria University of Wellington
dale.carnegie@vuw.ac.nz
ABSTRACT
In the past, most performances that have used Tesla coils as
musical instruments have been limited by low polyphony and
very rudimentary control of musical parameters, culminating
in minimally expressive results. This paper outlines recent
advances that have been made in improving the musical outputs of Tesla coils by way of software simulation, interfacing
and more nuanced control parameters. A description of the
hardware interface and the firmware used is provided along
with an explanation of the software interface and its simulation capabilities. The result is a new Tesla coil control system
that offers an unprecedented level of musical control and expressiveness while also providing a user-friendly interface for
real-time composition and performance.
1. INTRODUCTION
A Tesla coil is a resonant transformer circuit that generates
very high voltages which are made to arc through the air on
command. The effect is like arcs of lightening emanating
from a metal ball or toroid propagating through the air as
in Figure 1, and it generates a powerful and ever-changing
sparking sound as it does so. Musical applications of Tesla
coils involve inputting power to the coil in short pulses at the
frequency of the desired notes in order to create melodies and
other musical content. As electrical arcs grow from the coil,
ionizing and heating the air, they create periodic shifts in air
pressure in a similar way to the transducer of a loud-speaker,
causing a sharp and powerful wave of sound to be emitted to
listeners in the area. In this way it is also considered to be
a type of plasma speaker, differing primarily in that the duty
cycle is much smaller - in the system described here, power
is applied for only microseconds at a time.
In order to compose musical sequences to be played back
by a Tesla coil, controller hardware is necessary to convert
musical control signals, usually in the form of a stream of
Copyright: ~2015 Jason Long et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License 3.0
Unported, which permits unrestricted use, distribution, and reproduction in
any medium, provided the original author and source are credited.
Ajay Kapur
Victoria University of Wellington
ajay@karmetik.com
MIDI data, into pulses to control the coil. The management
of the timing and lengths of these pulses, including the length
of each pulse relative to its surrounding pulses, is critical to
the stability and musical functionality of the system. This paper describes the design and implementation of a Tesla coil
control system that makes use of the newly designed 'Chime
Red' control hardware, which provides a unique level of flexibility and musical expression to Tesla coil performances. First
a brief background of Tesla coils and their use as musical instruments will serve to put this research into context. A summary of the current state of Tesla coil controllers will then be
presented. Subsequently, an outline of the hardware implementation of the Chime Red unit will be provided, followed
by a description of the software interface and simulation system that has been created. The various new musical capabilities will be described, and plans for future work will be
outlined.
Figure 1. Pyramider - An 8 foot tall musical offline Tesla coil (OLTC) in
operation. Pyramider is one of the coils that has been controlled with this
system.
2. BACKGROUND OF TESLA COILS
The Tesla coil was named after its inventor Nikola Tesla, who
secured a patent for an early implementation as a 'system of
electric lighting' in 1891 [1]. They were used in several of
his experiments related to fluorescence, x-rays, radio, wireless power, biological effects, and the electromagnetic nature
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