Frameless Laser Harp

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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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Stormrage5 months 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)  Stormrage5 months 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 :)
jonnyboy3235 months ago
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 :)
Pushan Panda (author)  jonnyboy3235 months 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!
origamimavin5 months ago
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)  origamimavin5 months ago
Thank you! Do put up some pics after you are done!
starphire5 months 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)  starphire5 months 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.
nanaverm5 months ago
Wow! This is like a visible version of a theremin, and it sounds better, too.
Pushan Panda (author)  nanaverm5 months ago
:) That's exactly what i thought i when first saw it!
elliot42063 days ago
If anyone is looking for a kit for this project, I am selling them for $90! Just contact me and I'll send you a price list.
elliot42063 days ago
Pridmoremd, that stepper doesn't work. I've tried that one too.
pridmoremd4 days ago

Mine is not working either. Has anyone actually got this to work? There is no separation of the beam.

Jbuginas4 months ago
I'm using a 5V Stepper Motor 28BYJ-48 with uln2003 wired as per your great instructable, but it's not swinging far enough. Also, the beam is not visible using a 50 MW laser after it hits the mirror.

Are there any ways to tweak the motor movement part of the sketch  to swing further per step?

I've tweaked the motor and laser delay variables, but can't figure out what controls the distance of the steps. I think it may be a difference in stepper specifications/angles. Steps per rotation, etc. 

Any hints as to what kind of mirror to  shop for and where?

has anyone modified this to use the Arduino stepper library?

I'm excited to have time to build this now, it is a great project.
jboorom Jbuginas3 months ago
Was anyone able to get this to work using the 5V Stepper Motor 28BYJ-48? And if so could you please share any code or wiring changes that were made?

Did you hear back about using this stepper? Im trying to bulid it myself and it just vibrates...

For a harp, i think more power will solve your problem. I read 200mW is the minimum. I use a 500mW and work great during stepper moves. About the stepper, i will replace it with cheap galvos trop eBay.
pridmoremd made it!5 days ago

Here is setup with 5v 28YBJ-48 Stepper Motor

pridmoremd5 days ago

28BYJ-48 stepper motor

In the process of making this, using the 28BYJ-48 stepper motor. Checked forums, a lot of people asking about using this stepper but no one really answering if this is feasible. Set up exactly like indestructible but only getting vibrations. Any advice?

kiscool1 month ago
Hello to all
i am currently designing a laser harp based on arduino and using a stepper motor. Unfortunately, the stepper speed is not sufficient toi get a permanent image of the beams. It's working but not fast enough. My harp will be customizable with six presets.Each one could be sets to produce 13 notes maximum. 9 beams is actually the max confortable for the eye but is flickering a lot. Which stepper to use to solve this problem ?

Thanks to all !

Hi kiscool,

I'm also in work... I use a Epson Mot1- Stepper. It's fast enough but only 20Steps per revolve. The angel of the beams are too much.

I have to search some stepper with 0,9-2°. Otherwise maybe it's possible to take a inexpensive set of galvos. Some costs around 100€ at ebay. And the unused selling at ebay?

greets from germany


Hello ttäschner,
Yes, that's what i'll do about galvos. Actually, the system contents a 20x4 backlit lcd and is ok. All messages for it are done and ok. Next step : galvo and then the detector. I will also place a LED matrix for indicating which preset is in use. I will also add footswicth for the harp control.


just bought a stepper with 1,8°. Will check it tomorrow. I'm searching for a way to control a single galvo with the arduino. It seems to be not so easy. Because there is no controling interface which can take the Hi/Low TTl signals from arduino an switch it to fast voltage like

Arduino step output HI -> galvo turn on Beam 1 (2,5V)

Arduino step output LOW -> galvo turn off Beam 1

Arduino step output HI -> galvo turn on next Beam (3V)


there must be a way to tell the galvo the beam angel and count and so on....

I think you have to use pwm, then create a dac toi get analog signal from 0 to 5 volts. Finally, create a circuit to concert 0-5v to -5/+5v. In fact, galvo drivers operate with -5/+5v signal

Can i use a 28BYJ-48 stepper motor for the harp???There are commments saying that it cannot work fast enough to look as continuous beams.Also Can i see the beams if i use a 50mw 532nm Laser???????

Please reply.I am at the brim of making one harp...

You will probably see the beams using fogmachine. But more power you have, better results... i use 500mw but 200mw is the minimum.

have you made the laser harp using the same specs in the instructables??Will it work perfectly??? Which stepper must i use for a good result???

You will probably see the beams using fogmachine. But more power you have, better results... i use 500mw but 200mw is the minimum.
albuser4 months ago
I asked the guys at and they told me that I need a laser with Transistor-Transistor Logic so it can turn on and off at high speeds, is that true or will any laser work?
Jbuginas albuser3 months ago
Any luck? My laser doesn't seem to pulse, perhaps eyesight isn t keen enough? It does turn on and off, but when the sketch is running, it just looks solid. Of course pm the mirror isn't moving fast enough yet, either. 
albuser Jbuginas3 months ago
Yeah, I tried using just a regular handheld pointer and it turns on and off at high speed, it looks solid but try waving it back and forth and you should see gaps in between streaks of light. I actually did get the stepper motor to move fast enough but I really have no idea what I did differently than the first time I tried it, other than using a different power supply and a new ULN2003. I can't get the photoresistor to actually sense the light and play a note but I haven't had the time to really examine it yet.
kiscool albuser1 month ago
I use a rgb laser with analog modulation but ttl is ok too. With this kind of laser, of course it's simple...
jameswenzel2 months ago

how did you go about attaching the mirror to the stepper?

Personnaly, i use two components epoxy glue. It works...

Can i use a 28BYJ-48 stepper motor for the harp???There are commments saying that it cannot work fast enough to look as continuous beams.Also Can i see the beams if i use a 50mw 532nm Laser???????

Please reply.I am at the brim of making one harp...

TechGeek011 month ago

Can you direct me to a visible green laser like this on Amazon? I can't seem to find one there. It has to be Amazon, though.


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