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Frameless Laser Harpby Pushan Panda on September 23, 2013

Table of Contents

Frameless Laser Harp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Intro:   Frameless Laser Harp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 1:   Overview of the harp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Step 2:   Parts.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Step 3:   Wiring guide for steppers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Step 4:   Wiring it all together: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Step 5:   Arduino code: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

File Downloads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Step 6:   MIDI interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Step 7:   Layout and enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Step 8:   Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

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Advertisements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

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Intro:  Frameless Laser HarpWe 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 particularlywell 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 littlehelp 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 lightsensor, 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 careto 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, mentalor 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. Partresearch, 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 initself gratifying. And there’s always room for originality and improvement in the future.

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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 :

Image Notes1. Please view this image in fullscreen mode.2. Please view this image in fullscreen mode.

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Image Notes1. The wonderful patterns that smoke makes with a Laser.2. The wonderful patterns that smoke makes with a Laser.

Step 1: Overview of the harpThe basic outline of the harp:A laser beam is shone. A stepper motor with a mirror divides it into nine beams. When one or more of the beams are cut, the light sensor (Light Detecting Resistor, LDR)detects it. According to the corresponding motor positions, it sends signals to the Arduino, which in turn produces the respective notes through a computer or keyboard.

How the beam is created:A mirror is attached to the motor. The laser beam is directed to the mirror. The motor rotates in steps, hence stepper motor. With every step the motor takes, the positionof the mirror changes, deflecting the beam in a different direction every time. The steps take place fast enough for the beams to appear as if they are simultaneouslypresent.

How the harp knows which beam has been cut:Every beam has a corresponding motor position. When a beam is cut, it reflects onto the sensor, which detects an increase in light intensity. The light sensor then looksfor the position of the motor at the instant the beam was cut, and thus identifies the beam in question.

Image Notes1. Please view this image in fullscreen mode.2. Please view this image in fullscreen mode.

Step 2: Parts..

Here you will find the complete parts list you need and some info to create the project yourself:

Main partsStepper motor:A stepper motor is an electronic device which converts electrical pulses into extremelysmall mechanical movements (steps). Its shaft rotates by taking these steps when theelectrical command pulses are applied in the required order, and its speed and directiondepend on their frequency and sequence.A stepper motor has the following attributes:•Number of steps per rotation•Torque (the weight it can bear)•Step angle accuracyBy manipulating the control pulses, you can make the stepper motor carry out differentfunction such as taking half steps (e.g. 400/rotation instead of 200).For our project we will be operating in full step mode.

Arduino:Arduino is basically a small computer which reads an input, interprets it, and sends an output, where the input,output, and interpretation can be practically anything (in

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the electronic field!).It is a magical board which makes your electronic dreams come alive.

Bread board:Because the solderless breadboard for electronics does not require soldering, it is reusable. This makes it easy to use for creating temporary prototypes andexperimenting with circuit design.Laser:The more powerful your laser, the more effective your harp will be, ours was rated at: <50 mWAnd as for color, we've chosen green, since it was completely safe for the skin at that power rating.

Rest of the parts and tools that you will need:Resistor 220 ohms 1/4WULN20032N2222 TRANSISTORLDR Light SensorMIDI jackMIDI to usb adapter. (This parts is optional, it has been explained in the MIDI section)5k TRIMPOTSmall MirrorGreen Laser Safety GogglesWhite GlovesPower Supply, 12V DC 2A (This parts depends completely on your stepper motor, go by its rated power)Soldering ironMaterials for the enclosure

Total estimated cost: 90 - 100 $

Image Notes1. Please view this image in fullscreen mode.2. Please view this image in fullscreen mode.

Image Notes1. MIDI Jack2. ULN20033. 2n222 Trabsistor4. 220 ohm resistor5. 5K Trimpot6. Light Dependent Resistor

Step 3: Wiring guide for steppersIt is essential to send the command pulses in the right order. A step motor willtypically have six wires. Here is a quick guide to identify which is which.With the help of a multimeter, we first isolate two groups of three wires, formingtwo coils, by checking the continuity function, ensuring that the circuitis complete.

Next we identify the middle wire of each coil. Using the resistivity function, checkthe resistance between all combinations of pairs of wires. The resistance betweentwo ends will be twice that between the middle wire and either end.

If your stepper motor does not have 6 wires, here is a wonderful resource to help you out:

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Step 4: Wiring it all together:In the first image you will see the fritzing diagram for the harp. And in the following images you will see the step by step process for building the circuit on yourbreadboard.

We begin by placing the ULN2003, keeping in mind the direction of the little notch on the chip.We then wire the stepper motor's signal pins into the chips OUT pins and the common wire into the chip COM pin.In this step we connect to the arduino via the chips IN pins and we connect our power supply to the chip.For the next steps we add the transistor, the laser, the LDR and the MIDI jack.Refer to the fritzing diagram (first image) if anything is unclear.

Your circuit is now ready!

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Image Notes1. The little notch is on this side

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Image Notes1. Arduino +5v via 220 ohm resistor.

Step 5: Arduino code:Copy and paste the Arduino code below into a new sketch,If you don't know how to create/upload a sketch, check out the official Arduino - Getting Started page. If youwant to learn more about a specific command, just Google it.

We were having trouble embedding the Arduino code, so please click here for the code.Or download the arduino files directly from this step.We have put comments all along the way to make it easier for you to understand the code.This is not the most efficient code, but it works.

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File Downloads

Laserharp.ino (10 KB)[NOTE: When saving, if you see .tmp as the file ext, rename it to 'Laserharp.ino']

Step 6: MIDI interfaceOk! So we are finally ready to make some music!

There are two options that you can take:Option 1:Plug your harp directly into a MIDI keyboard and you are good to go.But if you want more control then go for Option 2.

Option 2:For this option you need a MIDI to USB converter, like in the first picture.This works with any software that deals with MIDI, Here we show you how to go about it using FL Studio:

3rd Picture: First open FL Studio up, then click the OPTIONS button on the upper left corner and navigate to the MIDI settings. then select your MIDI device.

4th picture: The next step reveals the magic of MIDI, Right click on one of the tabs, in the Insert tab you will see a whole bunch of different sounds available to you,ranging from the classic sounds to the most modern sounding synths. Feel free to experiment with these sounds until you find your favourite one.

Image Notes1. MIDI to USB converter

Image Notes

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1. MIDI settings

Image Notes1. Right click here:2. All these wonderful options!

Step 7: Layout and enclosureAfter some sketching we were quite satisfied with this diamond form for our harp.For this step we encourage you all to come up with your own personalised enclosures.We will simply walk you through our design process:We began with some simple brainstorming, and then we sketched out a few forms.Once we were satisfied with a form, we modeled it on Cinema4d to scale,By modeling everything to scale we could do accurate dimensioning so that all our parts fit snugly into the enclosure.Since time was not on our side we could not make the enclosure out of wood, and so we decided to make a paper model of it.The layout for the components we chose is depicted in the second picture, the motor and the laser are seperated from the arduino and the bread board by a smallwooden platform.

Image Notes1. Arduino2. Bread board3. Laser4. Stepper motor

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Image Notes1. This is our temporary enclosure, Its made out of translucent plastic sheets.

Step 8: ConclusionWhat we learned:

Persistence of vision – this is what enables us to see the beams all at once,since the refreshment rate of the human eye is smaller than the rotation rate ofthe motor.

How a stepper motor and Arduino work – we have elaborated on these in thededicated sections.

Physical programming – people are often under the impression thatprogramming is contained within the computer, but here we looked at apractical aspect of it where it controls physical actions.

The design process – steps from ideation to creation for acomplete product.Concluding thoughts:Of course we made mistakes. Research is of paramount importance, especially when purchasing your parts – Google is your friend. But other than learning from our

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mistakes, we also learned to work as a team, by using each one’s plus points, and guiding those in unfamiliar territory when in one’s own comfort zone. We definitelycould havedone a better job with time management and organisation (which seem to be persisting problems with us), and in keeping up levels of energy and enthusiasm (whichwent through more downs than ups). Owing to our age and temperament, we underestimated the project and overestimated our capacity. We could not thereforeaccomplish the project as we had intended to. We would have very much liked to customise the harp by turningit into a complete package, giving it a name and logo. We also wanted to add elements to further enhance it -- controlling the volume and pitch according to the height atwhich you cut the beam, having the facility to sustain a note without holding your hand on it (pedal), using a RGB laser to have changing coloursaccording to the mood of the music, having the beams converge and diverge, and other visual effects. They remain prospects for our next edition.

Image Notes1. Please view this image in fullscreen mode.2. Please view this image in fullscreen mode.

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