Group 8 – DIY Musical Instrument
VIVA VIOLIN
PLANNING
Purpose
The aim of our product will be that it serves as a performance tool that provides an enjoyable and interactive experience for performers, artists or anyone that might be interested in violin as an instrument. This would be done using arduino and combining the inputs and outputs to achieve our end goal.Using lasers and buttons to control which laser is on , LDRs and a button to control which notes are played and weather its a sharp or a flat.Adding on visual feedback using lEDs with the notes played.
Objective
We aim to create an interactive violin that’s not only interesting to play, but also easy to make yourself out of a few components and an arduino kit. Making it exciting to play has to do with the way the violin looks in the end. So we decided instead of making it out traditionally from wood, we would make it out of a combination of wood and acrylic so that you can see all the intricate parts of the circuit and what goes into it.
Target Audience
After doing our market research we agreed as a group to target performers, artists or anyone who enjoys playing musical instruments in general that would like to experiment .Its a DIY musical instrument making it simple enough to make, put together and play with the basic knowledge of how violin or any musical instrument operates.
Market Research
As a group, we all agreed that a more modern looking violin would appeal to our target audience more. Since we are targeted towards musicians, both professions and armatures, we wanted to design a violin more eye catching and made out of other materials other than the basic traditional wood. We looked at other modern violins that existed, and from what we found most modern electric violins tend to be hollow made out of brightly colours plastic. We also looked into DIY violins and electric string instruments like an electric guitar, or the more playful version, guitar hero, to get some ideas on how we were going to create our own electric violin. We found that most DIY violins were made out of cardboard and don’t tend to have slick finishes.
Initial Brainstorm
We explored both the design as well as technicalities of violin when we first thought of the project . Coming up with two mind maps that each include information that we already know or gathered through market research to reach our final idea
Idea Process
Creating a non typical looking violin
◦ Making it out of few components and easy to make to establish the DIY aspect of the product
◦ Having same functionality as violin
1. Using buttons on the handle to mimic the motion of fingers pressing on the string
2. Using 4 lasers parallel to 4 stings
3 . Using a bow to trigger the sound and not moving away from its original functionality
◦ Attention to detail :
1 . The 2 laser receivers are spaced so that only one laser hits the receiver at a time
2. The bow is curved near the right end so that it’s more intuitive to the user to hold that end
◦ Extra functionality : button added on the bow to control sharps
Project organisation and time management
Gantt chart 
Task list
CONSTRUCTION
Low-fi Prototype
Week 1: 19/11/2018 – 25/11/2018
We began the Construction process with Low – fi prototypes. We created sketches on the features of the violin and where we want to place all the sensors, lasers and buttons referencing to how you typically play a violin
We then moved on to a foam prototype of our violin so we could observe the dimensions of a violin and how all our components would fit on to the violin
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Circuit Wiring
Week 2: 26/11/2018 – 02/12/2018
The four laser emitters and five buttons were wired up with colour coded wires and heatshrink tubing. This allowed for the flexibility in their placement on the violin, along with a uniform visual effect of the wiring. The wires were initially kept longer than needed in order to test the ideal placement of each component
Testing Circuit
Week 3: 03/12/2018 – 09/12/2018
The testing of the circuit was carried out in three stages:
- Testing the laser and button combination
- Testing the LDR when lit by the laser/button combo (giving us the ideal LDR sensitivity value for our lasers)
- Testing the code for 4 laser/button combos and 2 LDRs with a button
The third testing stage was carried out with the code given below:
int ldr[] = {0, 1}; // A0, A1
int laser_btn[] = {2, 3, 4, 5}; // laser buttons
int bow_btn = 10;
char notes[] = {‘C’, ‘D’ , ‘E’, ‘F’, ‘G’, ‘A’, ‘B’};
String sharps[] = {“C#”, “D#”, “no sound”, “F#”, “G#”, “A#”};
int notesLen = sizeof(notes) / sizeof(char);
int sharpsLen = sizeof(sharps) / sizeof(String);
//TODO:
//- get sounds working with piezo
//- add potentiometer to set volume (or tone length/sustain)
void setup() {
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)); i++) {
pinMode(laser_btn[i], INPUT);
}//endfor
pinMode(bow_btn, INPUT);
Serial.begin(9600);
}
void loop() {
if (isOn(bow_btn)) {
playSharps();
}
else {
playNotes();
}
delay(20);
}
void playNotes() {
if (isLit(ldr[0])) {
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)); i++) {
if (isOn(laser_btn[i])) Serial.println(notes[i]);
}//endfor
} else if (isLit(ldr[1])) {
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)) – 1; i++) {
if (isOn(laser_btn[i])) {
Serial.println(notes[notesLen – (3 – i)]);
}//endif
}//endfor
}//end elif
}
void playSharps() {
if (isLit(ldr[0])) {
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)); i++) {
if (isOn(laser_btn[i])) Serial.println(sharps[i]);
}//endfor
} else if (isLit(ldr[1])) {
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)) – 2; i++) {
if (isOn(laser_btn[i])) {
Serial.println(sharps[sharpsLen – (2-i)]);
}//endif
}//endfor
}//end elif
}//end func
bool isLit (int sensor) {
bool lit = false;
int lightLevel = analogRead(sensor);
if (lightLevel <= 30) {
lit = true;
}
return lit;
}
// return true if button on
bool isOn(int btn) {
int bState = digitalRead(btn);
return !bState;
}
Start Construction of Final Product
Week 3/4: 05/12/2018 – 10/12/2018
Two sheets of blue acrylic were laser cut to the design and size we decided on. Then an opening was drilled in the top face to push the lasers through so that app the wires and contained and the lasers and the only thing visible on top. After that the circuit was fastened to the bottom and it was tome to attach both faces. Using 3 clear acrylic supports glued near the middle and right of the violin the put together the 2 faces , they were then clamped to keep everything in place . The bow was next , button was added , two holes were drawn to put in the two receivers and curved near the end. Lastly the handle was attached after being shaped and the 4 buttons were attracted to it .
MAKER MANUAL
Intro
An interactive, modern, fun violin to be able to build and play yourself! Any age of any music skills can be able to play this futuristic instrument. Combination of both technological and traditional sounds.
What you need
- 2x Texas Instruments CD4051BE Analogue Multiplexer / Demultiplexer – https://www.rapidonline.com/Catalogue/Search?Query=4051%20multiplexer
- 1x Long 6 Pin Female Stackable Header Range – https://www.proto-pic.co.uk/long-pin-female-stackable-header-range.html
- 2x Long 8 Pin Female Stackable Header Range – https://www.proto-pic.co.uk/long-pin-female-stackable-header-range.html
- 1x Long 10 Pin Female Stackable Header Range – https://www.proto-pic.co.uk/long-pin-female-stackable-header-range.html
- 1x Adafruit “Music Maker” MP3 Shield for Arduino – https://thepihut.com/products/adafruit-music-maker-mp3-shield-for-arduino-mp3-ogg-wave OR piezo
- 2x LDRs
- Wires
- 5x buttons
- 1x Arduino board
- 4x Generic 5v laser emitter
- 7x 10k ohm resistors
How to Build
- Put together the arduino board using the fritzing sketch found below
2. Use the cut outs of the violin provided to create the base structure of the violin. Attach together all the pieces together except the final top piece to allow the arduino circuit to fit inside
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3. Attach the buttons and LDRs to the handle and bow of the violin
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4. Feed through the lasers through the slit of the top cut out of the violin and stick them down in a line
5. Attach the top of the violin with a glue and fit in the arduino circuit
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6. Plug in the violin, upload the code and enjoy Viva!!!
Programmer guide – Code
The code for the final version of the Viva violin is given below. The I/O variables define the pins used on the Arduino, the notes[] and sharps[] arrays define what notes will be played, and the lightThreshold variable controls the value of the LDR sensor reading when hit by a laser. The code includes a main program, along with a header file “pitches.h” (full pitches.h file can be found here: https://www.arduino.cc/en/Tutorial/toneMelody)
The program’s functions explained:
- Setup initialises the button inputs and sets up the serial port for debugging.
- Loop plays either sharp or regular notes depending on whether the button on the bow is pressed.
- playNotes checks which LDR is hit by a laser, and plays a corresponding note (notes 0-3 for LDR0, notes 4-8 for LDR1) from the notes[] array.
- playSharps works similarly to the playNotes function, but using the sharps[] array.
- isLit returns true or false depending on whether the LDR is hit by a laser.
- isOn returns true if the given button has been pressed down.
#include "pitches.h"
// define I/O
int ldr[] = {0, 1}; // A0, A1
int laser_btn[] = {2, 3, 4, 5}; // laser buttons
int bow_btn = 10;
int speakerPin = 9;
// define notes used
int notes[] = { NOTE_C4, NOTE_D4, NOTE_E4, NOTE_F4, NOTE_G4, NOTE_A4, NOTE_B4, NOTE_C5};
int sharps[] = { NOTE_CS4, NOTE_DS4, 0, NOTE_FS4, NOTE_GS4, NOTE_AS4, 0, NOTE_CS5};
int notesLen = sizeof(notes) / sizeof(int);
int sharpsLen = sizeof(sharps) / sizeof(int);
// define note duration
int noteDuration = 1000 / 4; // quarter note
// define LDR sensitivity
int lightThreshold = 30; // Increase this number to 50-150 if the function isn’t triggering with your laser emitters
void setup() {
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)); i++) {
pinMode(laser_btn[i], INPUT);
}//endfor
pinMode(bow_btn, INPUT);
// Serial kept for confirming everything works on Serial monitor
// Can be removed once everything works
Serial.begin(9600);
Serial.println(notesLen);
}
void loop() {
// if bow button pressed
if (isOn(bow_btn))
{
playSharps();
}
else {
playNotes();
}
delay(20);
}
// Play regular notes
void playNotes() {
// if LDR 0 on
if (isLit(ldr[0])) {
// for each laser (plays notes 0 to 3)
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)); i++) {
// if laser button on
if (isOn(laser_btn[i])) {
Serial.println(notes[i]);
tone(speakerPin, notes[i], noteDuration);
}//endif
}//endfor
// if LDR 1 on
} else if (isLit(ldr[1])) {
// for each laser (plays notes 4 to 8)
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)); i++) {
if (isOn(laser_btn[i])) {
Serial.println(notes[notesLen – (4 – i)]);
tone(speakerPin, notes[notesLen – (4 – i)], noteDuration);
}//endif
}//endfor
}//end elif
}
// Play sharp notes
void playSharps() {
if (isLit(ldr[0])) {
// plays notes 0 to 3
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)); i++) {
if (isOn(laser_btn[i])) {
Serial.println(sharps[i]);
tone(speakerPin, sharps[i], noteDuration);
}//endif
}//endfor
} else if (isLit(ldr[1])) {
// plays notes 4 to 8
for (int i = 0; i < (sizeof(laser_btn) / sizeof(int)); i++) {
if (isOn(laser_btn[i])) {
Serial.println(sharps[sharpsLen – (4 – i)]);
tone(speakerPin, sharps[sharpsLen – (4 – i)], noteDuration);
}//endif
}//endfor
}//end elif
}//end func
// Return true if LDR is lit by laser
bool isLit (int sensor) {
bool lit = false;
int lightLevel = analogRead(sensor);
if (lightLevel <= lightThreshold) {
lit = true;
}
return lit;
}
// Return true if button pressed down
bool isOn(int btn) {
int bState = digitalRead(btn);
return !bState;
}
Pitches.h file:
/*************************************************
* Public Constants
*************************************************/
#define NOTE_C4 262
#define NOTE_CS4 277
#define NOTE_D4 294
#define NOTE_DS4 311
#define NOTE_E4 330
#define NOTE_F4 349
#define NOTE_FS4 370
#define NOTE_G4 392
#define NOTE_GS4 415
#define NOTE_A4 440
#define NOTE_AS4 466
#define NOTE_B4 494
#define NOTE_C5 523
#define NOTE_CS5 554
#define NOTE_D5 587
#define NOTE_DS5 622
#define NOTE_E5 659
#define NOTE_F5 698
#define NOTE_FS5 740
#define NOTE_G5 784
#define NOTE_GS5 831
#define NOTE_A5 880
#define NOTE_AS5 932
#define NOTE_B5 988
How to Play
- Hold the end of the violin between your chin and left shoulder, in the same fashion as a regular violin. Hold the neck of the violin with your left hand and hold the bow in your right.
- Place the bow in line with the acrylic panel in front of the laser strings.
- Hold one of the four buttons on the neck to light up the corresponding laser emitter.
- Move the bow left or right to aim the LDR sensors with the light produced. Hitting the leftmost sensor will produce on of the notes CDEF depending on which laser/button is on, and the rightmost sensor will produce one of the notes GABC.
- Hold the button on the bow to obtain the sharp note equivalents of whichever laser/button is on. Remember that note all notes have a sharp note.
Interactions
buttons press handle -> laser one
laser on -> over LDRs -> sound of note
buttom press bow -> sharp notes
Design Decisions
The Viva violin uses four laser emitters to act as the “strings” of the instrument. This was inspired by the literal interpretation of the term “light strings”. The four lasers themselves are laid out on the violin in a row, similar to how strings are placed on a classic violin. Lasers were chosen over LEDs as they were found to be much more accurate for readings from a light sensor (used on the instrument’s bow).
The four buttons on the neck of the violin were used as an analogue to fretting strings. Each button is wired directly to one of the laser strings to emphasise this analogous connection.
The bow was kept similar to a classic violin bow in regard to its movement. It needs to be swiped across the strings to produce a note. Light dependent resistors were chosen as the sensors for the strings, as they are often found in common Arduino kits. Accessibility of components was an important factor in the creation of the instrument to ensure a simple prototype could be made by anyone with an Arduino kit.
The frame of the violin was created with a combination of wood and acrylic. This was done to connect it with both classic and electric violin design. The internals of the violin were left open using only clear acrylic panels as support beams to encourage modification of the DIY instrument. All the electronics are connected on a breadboard and can be removed or replaced depending on the needs of the instrument.
The Viva violin can produce 12 notes, starting from middle C (C4) to an octave above (C5). The initial plan was to use an Arduino music instrument shield which can emulate a multitude of instruments, including a classic violin using MIDI commands. Due to ordering time constraints, an alternative had to be used. The Piezo buzzer was chosen as an effective compromise, as it allowed the instrument to produce the required notes, along with being very simple to program, simplifying the sound modification for a DIY user.
