Introduction: Laser Box Music Laser Light Show

Picture of Laser Box Music Laser Light Show

I previously published an Instructable that described how to use computer hard drives to make a music laser light show. I decided to make a compact version using an electrical box and RC car motors. I am selling it on eBay:

Before I begin I should probably tell you that lasers are not good for your eyes. Don't let a laser beam bouncing off of an uncontrolled mirror hit you in the eye. If you don't believe it can happen then read this:

Step 1:

I made a couple of sample videos. The first one is the requisite EDM song.

Step 2:

For the second one I decided to go old school since when I was growing up I always associated music and lasers with Pink Floyd ;)

Step 3:

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The first step is to drill holes in the back of the electrical box for the On/Off key switch, DC power jack and the amplifier's 3.5 mm audio input and gain control.

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The next step is to drill a hole in the side of the threads of the conduit fitting for the screw that will anchor the rubber band that keeps the mirrors centered.

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Next I installed the On/Off switch, DC power jack and the conduit fittings that house the motors and laser.

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Next I soldered in the 12V to 5V converter that powers the laser. The amplifier runs off 12V while the laser uses 5V.

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Next I used an angle grinder holder to cut notches in the motor shaft couplers to hold the mirrors.

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Next I disassembled a hard drive to extract the highly polished aluminum platters to use for the mirrors. If you use glass mirrors then the laser will reflect off both the surface of the glass and the silver backing so you will wind up with two dots. This wiki article explains it. The other advantage of using the aluminum platters is that they can be clamped tightly inside the notched shaft couplers without breaking. If you buy non-working hard drives on eBay to harvest their platters, be sure to visit the HDD Platter Capacity Database to research the model number of the hard drive you are buying to make sure it contains more than one platter to get the most for your money. An older 250 GB hard drive may contain 3 or 4 platters while a newer 1 TB model may have only one.

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Next I made a table saw sled to cut the aluminum platters. I used a band saw for my previous laser project but the table saw made much cleaner and and straighter cuts. I briefly experimented with a 100-tooth table saw blade specifically made for cutting aluminum but my regular Dewalt 60-tooth crosscutting blade actually worked better. The trick is to set the blade at the highest attack angle and use toggle clamps.

WARNING: If you are going to be cutting metal with a table saw then you have to take even greater precautions. GO SLOW. Don't clamp both sides of the metal; Just one side or the saw will bind and throw the blade, teeth or metal at you and kill you. Don't attach a shop vac to the dust outlet when cutting metal because it can start a fire in the canister. Wear an apron or overalls and a full face shield, not just safety glasses, because those hot metal shavings flying at you can hurt.

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The next step was to install the amplifier. It had a very bright blue power LED that I was tempted to cut off so it wouldn't compete with the laser in a dark room but the way the amplifier is oriented the heat sink blocks it from direct view and makes it reflect a diffuse blue color inside the electrical box that gives it a really cool look.

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Next I installed the shaft couplers on the motors and inserted the mirrors into the notches and tightened the set screws. I replaced one of the set screws with a longer screw to hold the rubber band. Then I inserted the motors into the conduit fittings.

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I soldered the speaker wires to the motors on my first prototype but later switched to 2.8 mm female spade connectors after I accidentally burned out one of the motors by applying too much heat with the soldering iron. An advantage to using the spade connectors is that you can disconnect the lower motor so the laser only moves in a horizontal direction creating the liquid sky effect. I connected the right channel to the top motor and the left channel to the bottom motor but it really doesn't matter. It doesn't even matter which motor terminals the negative and positive leads attach as long as both are connected.

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Then I installed the laser module. It just clamps inside the 3/8 in. cable clamp adapter. The neat thing about the clamp is that you can easily remove the laser and swap a different colored laser pointer.

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Here is how everything is wired up. The rectifier diode was only needed for the blue and green laser modules. They were getting shorted when their metal housings were grounded to the electrical box so I isolated the ground of the 12V to 5V DC-DC step down converter with a 1000V 3A rectifier diode and that did the trick.

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Then I fired it up to test with a little fog from this fog machine. Watching the laser pattern is cool by itself but adding fog takes it to another level. With it you can see the actual laser beam as it cuts through the air. The best thing about using the conduit fittings to house the galvanometers is that everything is easily adjustable. Once the top fitting has been adjusted so the laser beam is reflecting off the center of the lower mirror it can be tightened and left alone but leave the lower fitting just finger tight so you can twist it to move the laser pattern up and down the wall or even onto the ceiling without physically tilting the box. The sharp teeth of the steel locknuts that came with the fittings would dig into the steel so much that they would self tighten to the point where it was impossible to loosen without tools so I replaced them with 3/4" PVC locknuts. The biggest advantage of using the motors over the hard drives, besides size, is that they allow for much greater mirror travel so you get a much wider pattern at closer distances.

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For the finishing touch I cut the corner out of the steel cover plate to make a window for the laser when it is installed. Leaving it off allows you to throw a slightly wider pattern and also project onto the ceiling. Again the table saw worked great for cutting metal.

WARNING: Again, if you are going to be cutting metal with a table saw then you have to take even greater precautions. GO SLOW. Don't clamp both sides of the metal; Just one side or the saw will bind and throw the blade, teeth or metal at you and kill you. Don't attach a shop vac to the dust outlet when cutting metal because it can start a fire in the canister. Wear an apron or overalls and a full face shield, not just safety glasses, because those hot metal shavings flying at you can hurt.

Step 18:

Here's another video that shows how it handles a variety of songs. It really allows you to "see" your music. It is also simple to use: You plug your audio source into the 3.5 mm audio jack, plug in the power supply, turn on the power, start playing music and adjust the gain control to adjust the size of the laser pattern. After I showed it to my family and friends they all wanted one so I made several using various colored lasers and decided to sell them on eBay: It comes with everything: The box, power supply, audio and power extension cables and audio splitter. Thanks for looking!


mariusdabija (author)2017-05-02

Hello everybody,

I've been trying to do this project and ... I'm not doing well. My engines are not spinning. I checked the voltage in the audio outputs and measured 30 mV. I think it's too little to reverse the engines.

Please help me and tell me what they are doing wrong.

Thank you in advance!

replayreb (author)mariusdabija2017-05-03

The only thing I can tell you is to make sure you use those uxcell 5000 RPM 6V High Torque motors I linked to in the parts list. I ordered motors from several different sellers on both Amazon and eBay and those were the only ones that had enough torque to maintain good control of the mirrors. Others I tried that looked identical with the same exact housing were too weak and made the pattern too loose and bouncy. Also, if you order those cheap amps from China make sure you order more than one because a full third of the ones I received were DOA or the potentiometers were cracked since they ship them in a plastic envelope, not boxed.

mariusdabija (author)replayreb2017-05-04

I changed the engines and it works. The amplifier gets really hot. I used a computer sound output, probably the signal too strong. I'll put some preamplified signal microphones to capture ambient sound. Returning ...

replayreb (author)mariusdabija2017-05-04

TD7297 amps are known to get really hot. I was concerned the impedance of the motors was too low when I first started testing but then found online that this is common though I can't imagine installing one in a sealed cabinet as many do to make a portable bluetooth speaker. They are also supposed to have a thermal protection switch but I never tripped it during my testing

mariusdabija (author)replayreb2017-05-03

Thank you,

I will make a few changes, I ordered several types of motors (and lower voltage). I will measure both outputs on the amplifier, I will even do a sound test.

Hope to have results :)

I will announce you and I will post if it works with the new engines.

Have a nice day!

bterry01 (author)2017-04-13

Not only a cool Instructable, but great description, doc and pictures. Excellent job!

replayreb (author)bterry012017-04-22

I finally had some time today to sit down to add more details and links to all of the parts.

replayreb (author)bterry012017-04-17

Thank you very much!

MStylesMS (author)2017-04-08

This is really cool! Do you mind sharing the electrical diagram?

replayreb (author)MStylesMS2017-04-22

I didn't like that crude schematic so I wired everything up today (outside of the box) and took a picture of it for you. Please note that those power wires are shortened greatly before installation.

replayreb (author)MStylesMS2017-04-12

Thank you. I'll draw something up and add it to the instructable.

DroneBot Workshop (author)2017-04-13

Awesome Instructable. You got my vote with the Pink Floyd!

Hard to go wrong with Pink Floyd ;)

anjoze (author)replayreb2017-04-18

Agree. Thank you

Mike X yt (author)2017-04-13

Nice Instructable!, its one of my favorites and because I feel that this instructable should get even more attention here is a gif you can use as the cover image.

replayreb (author)Mike X yt2017-04-17

I just added it to the Instructable. Thank you!

msameer39 (author)2017-04-14

Hats off for your creativity brother. Simply awesome. I am looking to see more from you in the future

replayreb (author)msameer392017-04-17

Thank you.

DoctorWizard (author)2017-04-13

For slightly less than the price of your box, also on eBay, you can buy a pair of professional <b>laser galvos</b>. They have a feedback circuit and can handle much higher frequencies. And they include front-surface optical grade mirrors. They are not mounted in a box at that price though.

With your design, you can increase the frequency response by keeping the aluminum mirrors as small as possible. Putting a capacitor inline with just one of the inputs will shift the phase and give you more of a circular, flowery pattern instead of a diagonal squished circle.

replayreb (author)DoctorWizard2017-04-13

Yes I looked at but in the end decided to keep it all analog to make it as simple and compact as possible. Since this this involves no programming, it's more pure or even organic in a way. You "see" the music, not someone's programmed patterns.

DoctorWizard (author)replayreb2017-04-14

The laser galvos take an analog input signal, and the voltage levels are compatible with a typical audio amplifier. Speed is not an issue for visualizing music waveforms. Purchasing the galvos could have saved alot of time and effort (but where's the fun in that!). Oh yeah, and I must echo the other comments-- Excellent choice of the Pink Floyd!

replayreb (author)DoctorWizard2017-04-17

I didn't realize those could take an analog signal. I was seriously going to go that route then came upon the idea of using inexpensive motors and discovered they fit inside the conduit fittings and then fell in love with the industrial look of the electrical box. Good thing I didn't know any better :)

ILykMakin (author)2017-04-17

Very impressive. With your eBay price at $99 (and not even accounting for materials cost), I hope you are able to build these in under an hour or you're HELLA selling your skills and times waaayyy short

replayreb (author)ILykMakin2017-04-17

You get it. I was just trying to gauge interest. It costs more than $50 in parts and accessories to build each one. I will have to raise the price if I decide to make any more in the future.

bpark1000 (author)2017-04-13

Some lasers have the diode's anode tied to the case, which is usually tied to the positive supply in the driver electronics. Either you need to insulate the case from ground (but have a scheme for heat sinking) or use an isolated supply to power that laser.

replayreb (author)bpark10002017-04-13

Where were you last month? I was racking my brain trying to figure out how to cool the diode while keeping it isolated before landed on the diode route. You know how expensive thermally conductive but electrically nonconductive tape is? lol

bpark1000 (author)replayreb2017-04-13

Cooling the diode is neither difficult nor expensive. You use standard hardware for mounting transistors, which routinely must be isolated from the grounded heatsink. You bolt the diode down, with insulating shoulder washers under the heads of the bolts, and use mica or kapton insulators with heatsink grease on each side.
I don't understand how a "diode route" solved this problem. Please explain. Another way to solve this is to float the laser driver circuitry off ground, and convey the on/off signal to it with an opto-isolator or level-shifter.
You must be careful, as shorting the laser diode's case to ground can bridge the driver, sending huge currents into the laser diode. This transforms the laser diode into a "dark-emitting laser" which emits energy that cannot be detected by any known device.

BiBi_MCU (author)2017-04-13

Nice project! Did you know what is the maximum movement speed. Normaly the value is mesure white in 5 degree and in khz

replayreb (author)BiBi_MCU2017-04-13

I don't know how to measure the speed it but I can tell you that I visited and had a lot of fun running the Laser Box through all the frequencies. My hard drive-based laser projector had a hard time with the lower frequencies without drastically lowering the volume because the actuators are physically limited but the DC motors with the rubber bands are practically bulletproof.

KwazyKanuck (author)2017-04-13

I LOVE this idea! It reminds me of a project I did in high school,
called a "Light Organ". You can really expand on this idea you already
have by adding a simple bandpass circuit for each Red Green and Blue,
for the Bass, Mid and Treble, adding a whole lot more variance to the

replayreb (author)KwazyKanuck2017-04-13

Yes you can do that by applying separate EQ settings to each laser box but for the purposes of the demo videos I was trying to show that the patterns are not some random bouncing of a mirror; Each song has it's own unique, repeatable pattern. All the boxes produced relatively the same pattern even though they were not synchronized in any way other than sharing the same audio signal.

ee_eng (author)2017-04-13

Interesting project. I was happy to see your cautions about metal cutting while fabricating parts for the unit. Excellent Job! However, I didn't see much mention of the hazards coming from the laser light beam.

You have spec'd 100mw lasers, which relatively speaking, are very high power units. For example, the typical "cat toy laser" outputs less than 5 mw and even those are unpleasant to the eyes when viewed directly. 100 mw lasers should be considered EXTREMELY HAZARDOUS when viewed directly. At these power levels photochemical damage to the retina (retinal burn) is clearly possible, and highly likely if viewed repeatedly or for an extended period of time.

This hazard exists for the builder (especially during setup and alignment) as well as the casual observer once this unit is put into use. Furthermore, REFLECTED LASER LIGHT (for example off of a shinny or mirrored surface) redirects the hazard at nearly "full power".

This means that the laser box builder must take extreme caution and should wear color specific laser eye protection (different for each laser color used) to protect his/her eyes during setup. Then, once in use, the device must be located to prevent any chance a light show observer might be able to view the laser beam directly OR off of a non-diffusing (aka mirrored, shiny, or metal) reflective surface.

Minimally, builders, buyers, and installers should review laser safety guidelines and wear eye protection before going forward with their task. There's lots of data available on the WEB for his topic. I suggest a starting point for laser safety information to be:

replayreb (author)ee_eng2017-04-13

Thank you. I added a precaution to my last laser project but frankly forgot to do so with this one. I'll go back and add that info.

jomac_uk (author)2017-04-13

A little tip here for the mirrors, ordinary glass mirrors can be used without producing 2 spots mentioned above. Using paint thinners and a cotton bud, the paint on the painted side can be removed revealing the mirrored surface that doesnt produce multiple reflections. The advantage here is that mirrors are easier to cut using a glass cutter.

replayreb (author)jomac_uk2017-04-13

You remove the paint and the silver is exposed from the back of the mirror as well? I didn't know that. Thanks!

RigoC (author)2017-04-13

Awesome. One tip. Hobby shops sell little mirrors. Single and double sided. Might be easier than cutting HD platters.

TimothyJ999 (author)RigoC2017-04-13

Another good source for front-surface mirrors is Item numbers L3129D or L14331 or L14359 would work. They also carry items like beamsplitters, prisms, and various lenses that might make for some interesting variations.

spark master (author)2017-04-13

Pink Floyd....LASERs for me it is like moths to a flame. Sorry I show my age, All lI can see is Lazarium in my minds ancient AMNH/Hayden the 70's ...

I know I ask a newbie question...but...what causes the red laser to give 3 colors?


replayreb (author)spark master2017-04-13

Each box uses only one color laser. What you are seeing in the video is 3 separate boxes each with a different colored laser.

AndreyB14 (author)2017-04-13

Too hard a way - if you glued the mirror to the center of the speaker cone, the effect was much steeper and to the music without delays as in your case. You can use filters for the dinamics for each color.

Sincerely, your Russian hacker.

mikenaly (author)2017-04-07

Very cool. If i might add a suggestion, in my opinion, it would add an extra dimension if you used filters on your audio outputs. Pass only the lows to one color, middle frewuencies to the second and highs to the third. Then each color will have a different "dance" to perform. Also, based on what you described with leaving the second mirror "finger tight, if you wanted to overlap the three beams, this could be accomplished by lesving thd first mirror loose in the same way, allowing you to change where the besm strikes the second mirror.

replayreb (author)mikenaly2017-04-12

Thank you. It could be done but you would have to install multiple lasers and prisms but that would greatly add to the size and complexity.

mikenaly (author)replayreb2017-04-12

Actually, based on your first video, turn the blue laser box clockwise and the red counter-clockwise until the patterns are pretty well lined up. To make each perform a different dance, put an inductor in series with the audio output and a capacitor across the output of one color and its movements will be primarily controlled by the lows (cutoff is based on component values). Switch the orientation of the same components on a second color, and all three doing something different.

graywoulf (author)2017-04-09

loving every aspect of this wonderful invention. Posting a few comments on YouTube as graywoulf. Thanks so much for sharing this!!!

replayreb (author)graywoulf2017-04-12

I saw your wonderful comments. Thank you!

fireballcz (author)2017-04-11

I like it, but:
The problem is, that your box react mostly to low accoustic frequencies, but not to music dynamics itself. I understand, that basses needs more power to reproduce and also corresponding mirrors actions must be greater. Did you think about using some kind of accoustic filter?

replayreb (author)fireballcz2017-04-12

I couldn't find an amp with a built in EQ small enough to fit inside the box but it could be applied to the input signal.

ThirdEarthDesign (author)2017-04-11

You had me at Pink Floyd, love it

dmedina8835 (author)2017-04-10

I dont like it i love it

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