ECE 791/792 Progress Report
Project Title: Electric Saxophone
Project Team: Michael Peña
ECE Faculty Advisor: Frank Hludik
ECE Courses Involved: 617, 618, 633, 634, 649, 651
Current Date: December 16, 2011
Project Completion Date: May 2012
General Problem:
The saxophone has a few problems that this project will hopefully improve upon. The
first problem is that a saxophone has a limited range which only encompasses 2.5 octaves. This
is due to the limitations due to the physics of acoustics. It is not physically possible to fit any
more notes on the saxophone. The saxophone has the smallest range of the ordinary woodwind
instruments.
Another problem is that practicing is loud and will often bother people, especially if the
player is a beginner. A beginning player may be discouraged and give up.
Design Objectives:
The electric saxophone will be able to produce a sound wave electronically instead of
acoustically. This will allow the saxophone to have an extended range as there will be no
limitations due to the physics of acoustics. The range will extend two octaves below and one
octave above.
Figure 1. Original Range
Figure 2. New Range
There will also be a headphone jack to allow the player to listen to the sound without
disturbing others while practicing.
Optional Objectives:
If I finish my desired goals early, I would like the electric saxophone to be able to
produce sounds from other instruments. This will allow a saxophone player to play many
different instruments without having to take years of practicing to master each one.
Implementation
The electric saxophone will consist of 6 different components. The arrangement of these
components can be seen in Figure 3. The major component is the Arduino Microcontroller. I
chose this microcontroller due to the wide range of attachments that are available for the Arduino
that relate to my project. It also has a low power rating which allows it to run on a 9V battery
that will fit inside the body of the saxophone. It also has a fast clock which allows for an
unnoticeable delay between button press and output. The next component is a Breath Pressure
Sensor. This outputs a voltage based on how hard the player is blowing. This will go into one of
the analog input pins of the Arduino Microcontroller. The Arduino will read this voltage and will
change the amplitude of the output wave in relation. The harder the player blows, the louder the
sound produced.
Another component is the Tonguing switch. This is a voltage divider circuit with a forcesensing resistor. The output will be fed into another analog input pin to the Arduino. There will
be a threshold voltage at which the Arduino will stop producing sound. When the tongue touches
the force-sensing resistor, the voltage at the output will lower and once it gets below a certain
level, the Arduino will stop producing sound. This feature is essential to playing a saxophone,
but is often overlooked. When changing notes or playing the same note repeatedly, the player
continually blows but touches his tongue to the reed to stop the vibration. This allows for some
space between each note.
The next components involve attachments to the Arduino Microcontroller. The first one
is a 64 button shield. This allows the Arduino to monitor 64 different buttons with an 8x8 matrix,
as seen in Figure 4, instead of 16 with a 4x4 matrix. This shield will monitor at least 25 different
keys which will mimic the fingerings of an alto saxophone. The shield will have to operate in
Serial mode instead of SPI because the pins needed for SPI will be in use by the other
attachment. Optionally, the 64 button shield will monitor the keypresses of a 12 button numeric
keypad in order to change between different instruments. The second attachment is a music
instrument shield which contains a library of sounds. It contains 128 melodic instrument sounds.
This will default to the sound of an alto saxophone. It also has a jack for a speaker or
headphones. If I have extra time, I will allow the player to choose the sound of another
instrument for the microcontroller to output.
The last component is the switches. The will be arranged as seen in Figure 4. The
switches are magnetic reed switches in order to eliminate mechanical ware. They will fit inside
the body of the saxophone. There will be a magnet placed on the pads of the keys and when the
keys are pressed the magnetic field will cause the switch to close. All the circuitry will fit inside
the body of the saxophone and with the exception of a power switch and a speaker, it will look
like a normal saxophone.
Progress
I have decided on the implementation of the project and have ordered most of the
electrical parts. The schematic shows the intended set up for this project. I have found a
saxophone online for less than $100 which includes shipping. I can start building the circuitry for
the project and start testing the components as they function within the microcontroller before
the saxophone arrives. Once the saxophone arrives I can start integrating the circuitry into the
saxophone
Most of my time has been spent ordering parts and testing them. I ordered multiples of
each component so I could have extras if the original didn’t work or broke. This came in handy
when testing the magnetic reed switches. They are very fragile and the glass broke when I tried
to bend the pins to fit them into the breadboard. I believe if I surround them in heat shrink
tubing, they should hold together better.
Since different saxophone manufacturers build their saxophones slightly differently, I
will have to wait to measure the dimensions of the saxophone before I order the speaker. I will
also have to be careful when arranging the components inside the saxophone because the
saxophone needs to be able to come apart to fit inside its case. This means the force-sensing
resistor and the breath pressure sensor should be able to easily snap on and off depending on if
the saxophone is in use or not.
I have strayed from my timeline slightly. I originally planned to have all of the
components finished by November and to test each component through December. So far, I have
just gotten all of the parts I need and I have been testing each part individually instead of
implementing them and testing the circuit. For example, I have tested the switches but have not
tested them within the microcontroller. I was also not aware that the microcontroller shields
would need to be soldered. I soldered the shields during the last week of November.
Figure 3. Schematic
U1
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
U2
1
2
3
6
4
MusicInstrumentShield
Arduino
R3
30Ω
U3A
1P1
1P2
Force-Sensing
Resistor
50%
R2
C2
C1
0.01µF
1
2
3
6
5
4
1P3
64ButtonShield
U4B
1kΩ
U5
Speaker
Columns
680pF
PressureSensor
2P1
2P2
2P3
2P4
2P5
2P6
2P7
2P8
2P16
2P15
2P14
2P13
2P12
2P11
2P10
2P9
Rows
64ButtonShield
Figure 4. Button Matrix
Columns
Rows
Original Budget
Category
Microcontroller
Saxophone
Circuitry
Parts
Microcontroller
Hardware attachments
Buttons/Switches
Speakers
Breath sensor
Wires
Battery Connection
Miscellaneous
Total
Price
$40
$50
$100
$10
$5
$15
$10
$1
$50
$281
Current Budget
Category
Microcontroller
Saxophone
Circuitry
Miscellaneous
Total
Parts
Arduino Uno Microcontroller
Music Instrument Shield
64 Button Shield
Saxophone
Buttons/Switches x30
Breath sensor x2
Force-Sensing Resistor x2
Battery Connection x2
Shipping
Price
$30
$30
$23
$97
$24
$26
$12
$0.80
$30
$272.80