Instructables
We are a generation that love sound and light – can’t do without them really. Our most preferred time of day is night, or what we would call evening. We are particularly well acquainted with technology; doesn’t hurt these days. Our prerequisite for everything is that it be ‘cool’. Put it all together and in a stroke of brilliance, and a little help from our friend the internet, we have the ideal solution – a laser harp.

A laser harp, what on earth is that? Sounds kind of fancy doesn’t it? Well, it is basically what it says it is. The laser harp is an electronic instrument where a motor, a light sensor, a microprocessor Arduino, and, I’m sure you’ve guessed, a laser collaborate to produce beams, each representing a note (we will elaborate for those who care to read on). This harp though doesn’t have a frame: its strings stretch out infinitely into space – we know no boundaries.

Our inspiration was a video we had watched online and found rather fascinating. Apart from the fact that the prospect of creating it without too much expenditure, mental or monetary, was exciting, it seemed a project providing scope for learning in different areas, especially since we wanted to present it as a complete product. Part research, part reverse engineering led us to figure out its functioning. Admittedly, we have not contributed any addition to the original creation, but to achieve it was in itself gratifying. And there’s always room for originality and improvement in the future. 

If you like our instructable please vote for it at the top  right corner of the page!

For making this laser harp you will require basic soldering skills, and some experience working with the arduino.

Word of caution: Lasers are very harmful for the eyes, make sure you wear appropriate eye protection.

Our Video will be ready in another 12 hours! Do come back and check it out!


Here's the link to the video that inspired us :
 
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Stormrage1 year ago
One of my dreams was to have a laser harp. The only thing I need now is to go buy some 2n222 ULN2003 and, uhm my question was: What kind of/ speed/ steps, steper motor can I use? Hacking some old printer or something, any idea will be appreciated :)
Thx, and btw, one of the greatest and really simplest instructable for a complicated stuff that everyone could be amazed with :) Keep it up !
Pushan Panda (author)  Stormrage1 year ago
:)
The motor ive used is actually salvaged from some old electronics, any kind of stepper will do the job, you might need to modify the code a bit. I would be happy to help, just send me a message.
I was actually going to rewrite the code to work directly via usb, not through MIDI... Any ideas about that?
Well, the problem isn't in the code really, now the problem is that I can't find ULN2003 here... Do you know anything compatible to that maybe? :)

also it would be cool if there is a way to get 3 lasers and make em switch colors hahaha just sayin :)
and, perhaps a positioning picture (where the circuit is, LDR and stuff would be good, cos I'm really planing to do a "Laser Harp Shield" for this one :)
This is awesome, great instructable!!! If you plan on only using it with the computer, and don't need the midi out jack, couldn't you theoretically use only the arduino, and scrap the usb/midi converter cable? There are loads of arduino projects out there that output midi via the arduino's usb cable (and maybe some software on the computer side too).
You could even make it wireless :) http://www.ladyada.net/make/xbee/midibee.html
Pushan Panda (author)  jonnyboy3231 year ago
Yes, i just checked it out, and it isnt too hard too send MIDI signals over USB!
That's a wonderful idea! Thank you!
Great 'ible! I have most of these parts laying around, and have been looking for something to do with some spare laser diodes and steppers. I saw this (or one just like it) on Hack a Day recently, and though 'How cool would it be to make one of these.' Awesome, thanks!
Pushan Panda (author)  origamimavin1 year ago
Thank you! Do put up some pics after you are done!
starphire1 year ago
I love how you've managed to simplify the hardware necessary for a laser harp. Well done! Since I already have most of these materials lying about, it looks like a fun project for an idle weekend.
I'm also curious how you would go about detecting the height at which a player was cutting the beam in an enhanced version of this instrument-care to share your thoughts? I would love to add that function.
Pushan Panda (author)  starphire1 year ago
Thank you! I would use an ultrasonic sensor to read the distance of the players hand, which in turn would control the pitch or volume of the midi notes.
nanaverm1 year ago
Wow! This is like a visible version of a theremin, and it sounds better, too.
Pushan Panda (author)  nanaverm1 year ago
:) That's exactly what i thought i when first saw it!
LeelaKrishna made it!5 months ago

I made my own code for this (Using stepper motor library and its much more efficient) and it runs fine. It also includes a start sequence where the laser goes back and forth slowly getting faster and faster until its a line and then it splits apart into the 13 different beams which include all the notes of the middle octave:

#include <Stepper.h>

const int stepsPerRevolution = 400; // change this to fit the number of steps per revolution

// for your motor

// initialize the stepper library on pins 8 through 11:

Stepper beamsplitter(stepsPerRevolution, 8, 9, 10, 11);

int LaserState = LOW; // The variable that stores the state of the laser beam.

int sensor = 8 ; // Change this value to calibrate your harp's sensor

int delaylaser = 2000; // If you increase this, the laser will be brighter, but the harp will be less fluid

int motorspeed = 100; // This variable affects the speed, and fluidity of the harp.

int stepsize = 2; //size between beams

int LaserPin = 7; // Tell the arduino that the laser is on pin 7

int startupspeed = 3;

int pos = 0; // position of the laser

int beams = 12; // number of beams

int pitch;

void setup() {

pinMode(LaserPin, OUTPUT); // Setup for laser.

pinMode(6, OUTPUT); // Setup for status led.

digitalWrite(LaserPin, HIGH);

delay(1500);

//start sequence

beamsplitter.setSpeed(startupspeed);

beamsplitter.step((-beams * stepsize / 2)-1);

for (int x = 1; x < 60; x++) {

if (x<30) {

startupspeed = 103 - (100/pow(x, 1.0/4.5));

}

if (x>=30) {

startupspeed = 103 - (100/pow(x, 1.0/1.0));

}

beamsplitter.setSpeed(startupspeed);

for (int pos = beams; pos > 0; pos--) { // turn in other direction

beamsplitter.step(stepsize); // direction

}

for (int pos = 0; pos < beams; pos++) { // turn in other direction

beamsplitter.step(-stepsize); // direction

}

}

beamsplitter.setSpeed(motorspeed);

Serial.begin(31250);

}

void loop() {

for (pos = 1; pos < beams; pos++) { // turn in first direction

beamsplitter.step(stepsize); // switch position

//delayMicroseconds(delaymotor);

digitalWrite(LaserPin, HIGH); // turn on laser

delayMicroseconds(delaylaser / 2);

if ( (analogRead(0) > sensor ))\ // If the sensor gets a signalx

{

digitalWrite(6, HIGH); // Switch on status led.

noteOn(); // Play note 3

}

else if (analogRead(0) < sensor ) // If the sensor does not get a signal:

{

digitalWrite(6, LOW); // Switch off the status led.

noteOff(); // Stop playing note 2.

}

delayMicroseconds(delaylaser / 2);

digitalWrite(LaserPin, LOW); // Turn off the Laser.

}

for (pos = beams; pos > 1; pos--) { // turn in other direction

beamsplitter.step(-stepsize); // direction

//delayMicroseconds(delaymotor);

digitalWrite(LaserPin, HIGH); // turn on laser

delayMicroseconds(delaylaser / 2);

if ( (analogRead(0) > sensor )) // If the sensor gets a signal

{

digitalWrite(6, HIGH); // Switch on status led.

noteOn(); // Play note 3

}

else if (analogRead(0) < sensor ) // If the sensor does not get a signal:

{

digitalWrite(6, LOW); // Switch off the status led.

noteOff(); // Stop playing note 2.

}

delayMicroseconds(delaylaser / 2);

digitalWrite(LaserPin, LOW); // Turn off the Laser.

}

}

void noteOn() // Function to play the notes

{

pitch = 60 - (beams + 1) / 2 + pos;

Serial.write(0x90);

Serial.write("0x" + pitch);

Serial.write(0x7f);

}

void noteOff() // Function to play the notes

{

pitch = 59 + pos;

Serial.write(0x90);

Serial.write("0x" + pitch);

Serial.write(0x00);

}

IMAG1440.jpgIMAG1441.jpgIMAG1442.jpgVIDEO0196_01_0000019432.jpg

Hi........ First of all congrats on making this successfully.

Is your system working...??? May i request you for a video...????

If you can send me video, please mail me on dixitad88@gmail.com

I used a 100mw laser and took the picture in the bathroom after filling it with steam from the shower.

I compiled the code and found this stray "\" on this line:

if ( (analogRead(0) > sensor ))\ // If the sensor gets a signalx

you're right but i don't think it really affected the code.

Yep! It doesn't make any difference at all.

I am considering using the L298N H-Bridge IC to drive the stepper mounted on a heatsink. Do you think that an EasyDriver Board could be used instead? I have a couple of them laying around.

Also, if you look at my picture, you see that my "strings" are infact pretty wide and rather thick vs being like a single line. This might be because i'm using a crappy transistor for the laser. Also the beam is ever so slightly off from the position its at when it turns on while it goes in one direction vs the other. for example: beam 3 when the motor is going from right to left could be about .5 cm away from where it is when its going from left to right, these beams do overlap mostly but you can still notice the flickering pretty well. I may just need to replace the transistor. Something else i might try soon is not have the the laser turn on going the other direction. ex: replace the current void loop w/

void loop() {

for (pos = 1; pos < beams; pos++) { // turn in first direction

beamsplitter.step(stepsize); // switch position

//delayMicroseconds(delaymotor);

digitalWrite(LaserPin, HIGH); // turn on laser

delayMicroseconds(delaylaser / 2);

if ( (analogRead(0) > sensor ))\ // If the sensor gets a signalx

{

digitalWrite(6, HIGH); // Switch on status led.

noteOn(); // Play note 3

}

else if (analogRead(0) < sensor ) // If the sensor does not get a signal:

{

digitalWrite(6, LOW); // Switch off the status led.

noteOff(); // Stop playing note 2.

}

delayMicroseconds(delaylaser / 2);

digitalWrite(LaserPin, LOW); // Turn off the Laser.

}

beamsplitter.step(beams*stepsize);

}

ajinkyadixit3 months ago

So... So... So..... Great Project...... But I am still not getting about where LDR is mounted so that it can detect every ray.... Please let me know where to put the LDR.... Thank You.

Pushan Panda (author)  ajinkyadixit4 days ago

Thanks!

The LDR has a pretty wide range of detection, I am putting it in my device facing upwards into the beams, so that when your hand cuts one of the beams the diffused reflected light is picked up as a spike by the LDR.

Ohkkk..... Means i can put it on the motor too.

jbennett384 months ago

I am hunting for a laser for this project. Unfortunately, for my application, I don't think a simple stylus laser will be enough. I'm trying to read up about lasers but I'm wondering if anyone can provide any feedback as to what they have found that works?

Pushan Panda (author)  jbennett384 days ago

My laser was rated at 50mW. Technically a stylus laser will do the job, but the beams will be very faint. You could ehance their appearance by adding some smoke in the room.

DARKHOURS4 months ago

Great project I would like to make sure its a 220 ohm you are using on the midi jack as another site on here instructable Send and Receive MIDI with Arduino say use a 2200 ohm I just want to be sure before hooking up to my computer .

Thanks

Pushan Panda (author)  DARKHOURS4 days ago

Im sure its a 220 ohm resistor!

22696789772 months ago

Are you connect the MIDI to your computer to play the music or use the digital

Instrument ? i only have a computer. can i play it by my computer? thanks!

Pushan Panda (author)  22696789774 days ago

Yes you can play it through your computer, I myself used FL studio to generate the sounds.

sebastianl11 month ago

hey, Im trying to do this for a project to my school,
coud you tell me what are the specifics of te steeper motor? or give your email so i can ask you some things :)
thanks

Pushan Panda (author)  sebastianl14 days ago

Hi sebastian, any stepper motor will be able to do this, but you will have to edit the code for your specific motor. I'll give you my email via personal message.

esalves16 days ago

Hi, great project, congratulations. However, I didn't understand how did you set up the light sensors. Could you please explain? Thanks.

Pushan Panda (author)  esalves4 days ago

Thanks. There is only one LDR on the device itself, its facing upwards towards the beams. When your hand cuts one of the beams the diffused reflected light is picked up as a spike by the LDR. Did i answer your question?

raphifouuuu made it!1 month ago

Hi ! Is it possible to have the wiring diagram of the 2N222 ? The wiring I did, work with a LED but not my laser :s I have followed the wiring of the project it does not work too. Would it be possible to have some advices.
Thank you. (Sorry for my English, i'm french^^)

10715924_10204907690561400_2018858785_n.jpg
22696789772 months ago

i‘d like to make this! i like it!

22696789772 months ago

i‘d like to make this! i like it!

DanieleV4 months ago

Mine doesn't send the midi out... I mean, midi cable's in led is blinking but i cannot hear any sound from FL Studio...

salexandridis5 months ago

So... I have tried using various stepper motors but nothing seems to work. Nothing works as it is supposed to. I thought that the problem might have been the motor, but I have recently purchased a NEMA 17 and guess what... it would just rotate uncontrollably. I attached a small piece of tape to observe whether its movement made any sense, but it didn't. There was no pattern. Needless to say, when I attached the mirror and pointed the laser on it, my room turned into a disco! The laser was reflected everywhere. It didn't even form single dots; only blurry lines. Also, the IC got EXTREMELY hot (I bet it would start to smoke, if I had left it plugged in for any longer).

Anyway... It seems that the author of this Instructable is reluctant to help sorting this issue out. Other people have the same problem, as well, but they got no answer. Even I haven't got any assistance when I initially posted a commented on this Instructable presenting the issue. So, if anyone else has succeeded in resolving this problem or has any idea about what might be wrong, please post an answer to this comment.

Thank you in advance, salexandridis

PS.: I don't mean to be offensive to the author and this might be just a misunderstanding, but me and other users have invested some money on this project.

I have gotten it to work by using the stepper motor library, check out my comment. I used a .9 degree stepper motor and had it go 2 steps for each beam because they were too close else how. I like the way it turned out. My stepper motor was actually bipolar so i used an h bridge instead of the uln2003

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