Picture of Music LED Light Box

My original LED light cube got allot of reactions. Some of them where about making the LED's react to music. This did sound very interesting and I found some instructables on here.
Unfortunately I found it very hard to understand those instructables. In my opinion they weren't explained well enough and even some circuits weren't correct.

That's why I though I build one and make an instructable of it. I tried to make this instructable so easy, that everyone with or without any experience can make one!

If you make one, don't forget to share your end result photos and movies with us.

Below you'll see the end result of my Music LED Light Box.

The movie is shot with my Canon Digital Camera, in the dark. My camera can't handle the fast switching between light and dark very well. In reality the effect is even nicer then on the video.

Before people go asking who's music or what songs these are in this video, these beats are made by my brother.  :)
You can visit his website or  YouTube channel for more information and songs.

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Step 1: Materials & Tools

Picture of Materials & Tools
To make this Music LED Light Box you can use many different things and build it different ways.
In this instructable I'll explain how I made it, a very simple way.

- 12v Adapter (a battery can be used as well)
- 3.5 jack headphone cable.
- tip31 transistor (this is the key to the whole project) - $0.50
- 5mm LED's (the color or amount is totally up to you, 1 LED per 3v. I used 12v, so 4 LEDs) - $0.28
- A4 acrylic sheet - 3mm thick (also known as 'plexiglass') - $2.00
- Fine sandpaper (I used 400) - $1.00
- Electrical Wire

If you see a price above, that means I bought it. The rest I just ripped of some old junk. The 12v Adapter was from an old wireless headphone and the 3.5 jack plug is from another old headphone.

- Jigsaw (also a Jeweler Saw can be used. But that's really hard to get straight lines)
- Glue Gun (hot glue, other glue to glue acrylic is possible)
- Drilling tool
- Solder tool (optional)
- Pen

Ones you've got this stuff you're ready to begin!

Step 2: Preparing the box

Picture of Preparing the box
From the acrylic sheet we're going to build the box.

1. Draw out the plates for the box on the acrylic sheet (photo 1). My longer plates are 15cm x 5cm. And the squares are 5cm x 5cm. Of course you can use any size for a box you want.

2. Use the jig saw to cut the plates from the acrylic sheet. Be sure to do this as perfect as you can. Because all plates need to line up nice with each other (photo 2).
If the plates don't turn out to be equal, you can sand the sides till they all fit nice.

3. Get the drilling tool and use a drill bit that is the same size as the thickness of the headphones cord (photo 3).  Then drill another hole for the adapter to go though.
When you're drilling, do this very carefully! You don't want to hurry, else you might put too much pressure on it and break the plate.

Step 3: Frosting and Diffusing

Picture of Frosting and Diffusing
To get the nice 'glowing' effect with the LED box, we need to have a 'frosted' look on the box and need LED's that are diffused.

I only could get my hands on water clear acrylic sheets and water clear LED's. For all those who have the same, continue with this step.

If you already have frosted acrylic (opal acrylic) and diffused LED's, then you can continue with step 4.

1. Get the fine sandpaper (400) and place it on a table, with the sanding side up. Get a plate and rub it over the sandpaper in a circular motion. If one side is frosted enough, turn the plate over and do the same with that side.
Now you'll have a nice frosted looking effect we need (photo 1 and 2 to see the difference).

2. Do the same with the LED's. Sand the LED's until they get the nice diffused look (Photo 3,4 and 5).

Photo 5 shows you 1 diffused and 1 water clear LED hooked on a 3v button cell.

Step 4: Building the box

Picture of Building the box
Now we've got the plates for the box, we need to put them together.

Before you go and glue parts together, make sure first they fit nicely onto each other. We need all parts to fit nicely.

1. After fitting the plates get the glue gun and glue the first 3 plates together. If you have some trouble holding the plates together before gluing, you can use some tape to hold them together. This way you can put the glue on more relaxed.

After gluing the 3 plates you should have something like photo 2

2. After the glue is dried, it's time to glue in the side plates. First place them and see if they fit nicely.
If not sand the sides a bit so everything fits nice together. Then glue them on their place.

The last (bottom) plate will not be attached yet. We need to put the whole circuit on the bottom plate later and then put it in place.

At this moment you should have something like photo 3 and 4.

Step 5: Preparing the circuit

Picture of Preparing the circuit
Since I have no experience in electronics whatsoever, this was the toughest part for me to find out.
Other instructables had no good explaining on this subject.

So for everyone who's new to this electronics stuff and have no idea what they're doing, here is some explaining for the circuit.

1. How many LED's to use?
The average LED needs 3v to work. If you are going to put the LED's in series (like I did) you need to calculate how many LED's you can use with your adapter. The formula you can use is adapter output voltage / LED voltage = Total LED's

So if you use a 12v adapter with the 3v LED's its: 12 / 3 = 4 LED's

You can also put LED's parallel in the circuit. But I'm not getting into this, just so that this instructable stays simple and easy to understand for everyone. Let's just focus now on the LED's in series.
If you want to experience with more LED's, you can always calculate your LED's and resistors here.

2. The real voltage on a adapter.
Before I went building this circuit, I thought it would be useful to measure the real voltage on the adapter. The sticker on the adapter (photo 1) says the output 12v. But once I hooked it up on my multimeter, it shows that the actual output is around the 18v (photo 2).

So that means I can calculate the LED's again: 18 / 3 = 6 LED's.

Since I'm going to make the LED's in series I can use 6 LED's in my circuit. 

3. The 3.5 audio jack plug
Which wire is what? That's what I was asking and trying to find out.
As you can see on photo 3, the plug itself has 3 metal parts, and 3 wires in the black protective layer.
On the photo I explained which wire is what.

Now with this information you can go to the next step, building the circuit.

Step 6: Building the circuit

Picture of Building the circuit
Many people get scared when they see all those weird circuits with those symbols on it. Having no clue what they mean.
That's why I made a instructable friendly circuit image :) See photo 1.

1. Make sure you have all the materials to make the circuit. And enough electrical wires to connect all the components.

2. Before we build the circuit, we first need to put the audio cable through the whole in the back.

3. Build your circuit, and test it out.  The best way to test it is through your audio output from your computer. Make sure the audio on your computer is set to 100% and then test it.

CircuitThe positive pole from the adapter goes to the positive leg of the first LED. Next the other 5 LED's follow. Hook the negative leg from the first LED to the positive leg of the second LED. Hook the negative leg from the second LED to the positive leg of the third LED, and so on. The negative LED from the last LED goes to the center pin of the TIP31.
Then hook the right pin of the TIP31 to the negative pole of the adapter.
All there's left now is to hook up the audio cable. Hook the red or the white wire from the audio cable on the left pin of the TIP31. And connect the ground wire from the audio cable to the right pin of the TIP31.

For better details please see photo 1, the circuit.

4. If your circuit works, solder all components together so the circuit stays together nice and strong and wont fall apart.

When done with these steps it's time to finish up!

If you have trouble getting the circuit to work, you can try to set it up first on a circuit board.
Carlosserious was so kind to make a how-to video on making the circuit, click here for the video.

Step 7: Finishing up

We've now got all the parts we need. All we need to do now is put the bottom part into the cube to make it a whole cube.

1. Use the glue gun again to put the connector for the adapter right behind the hole. Tip: Plug the cable in before gluing. This way the connector will always be on the right spot.

2. Sand the sides of the bottom plate so it fits snugly into the bottom. You just want the bottom plate slightly bigger then the hole it fits in. This way, once you put it in there, it will get stuck and won't let go while moving the cube. We won't glue the bottom, in case we need to open it for some reason. So make sure the bottom fits in tight.

That's it!!
Now plug everything in and put your music on max and enjoy!

You can change this project as much as you like. Use any LED's you want, create the box that fits the best on your desk, etc. You can also build the cube from my previous instructable.

I used photoshop to show you how different colors would look like (photo 7).

I tried to make this instructable the way so everyone can understand it. I'll try to answer them all. If you want to make one and get stuck, we'll try to get through it together.
If you have any questions please don't be shy and let me know.

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I'm testing my circuit on a breadboard (just like your linked video). I can't get the LED to respond to the music, it lights up as soon as I plug it into anything, music or not. It stays solid and won't respond to the audio signal. Know what I'm doing wrong?

I'm so doing this, but I was wondering. Is there a way to sequence other lights to the individual parts of the tune? Like you have lights for the beats, but what if I want to add lights for the bass, and other?

I am doing something similar! Filters! Look up low, band, and high pass filter designs and split the audio signal to run through each one respectively. Now you have signal for bass notes, mid ranges, and high frequencies. I have a tentative schematic as well.

Very cool. Thank you. ^.^
stefaniboy10 days ago
Hey! Just ordered the components, so exited. I wondered of you could wire the leds up in a pararell connection and not a serial? So that you could use much more lights

I didn't design it, but yes parallel would work and you could also use a lower voltage as well

DanM1615 days ago

Do you know if you can use speaker outputs from a receiver instead of the headphone jack? My receiver has A and B outputs, B for extra speakers. Would it be too much power? It is a Technics SA-DX1050. That way I wouldn't have to split the audio and I don't think I can play the speakers and headphones at the same time.

vbhatia3 made it!29 days ago
My led are not reacting to audio cable . led are blinking countinously.
vbhatia3 made it!1 month ago
Please tell me the exact number of the transistor the shopkeeper gave me tip31co.
lauren1522 years ago
i have done everything you did except i cut the adapter cord and attached it to the led and tip35, everything works perfectly except when i plug it in i cannot hear music coming from my computer or phone or anything. what am i doing wrong?

Please tell me the exact number of the Transistor use

Haha, it's amazing, thank you!

alex.laius.32 months ago

How do you get the cloudy look on the plexiglass? With sanding?

You can buy it already like that, or use glass frosting that you can buy at Home Depot to spray-on.

BritR1 month ago
Looks cool... Thanks :)

where can I purchase the small electrical wiring you are using in the instructions and the battery?

18V out of a 12V adapter?! Man that's not normal!

roofy994 years ago
 When I stripped my headphone cable it didn't look anything like the ones in your photo. I used an old pair of apple ipod headphones. They had 3-4 seperate strands but they weren't like wires like yours are. Am I using the wrong type of headphones, or what should i do to fix it?

Thank You
AiurI roofy993 months ago

Almost all headphones have other contacts etc. For example my headphones i stripped wire from have many little golden wires, then isolated 3 other ones, black, green and red (They are also gold after stripping)
So, i figured it out, that green is left headphone, red is right, black then has to be ground. Check inside of your separate headphones to see what cabeles come from / to them and You will probably know then, unless R and L are the same colors, but really You don't need to care about which channel is used.

same thing! have u figured it out?
melt the enamel with a small flame 'till they are gold colored then solder as normal
gabrielguy3 years ago
so 20 leds would be 60 volts!?D:
AiurI gabrielguy3 months ago

It's quite f...d up, it actually could be less than 60 volts. It depends on the type of LED diodes. I for example i could power 1 bigger LED 3v diode, so it could be bright enought with 2 3v batteries, because with only one it was dark. Also, i powered up 5 smaller 3v LED diodes using 1 3v battery and they were very bright. I am really confused about that.

in one line yes in bridge no :D
Reganne983 months ago
We built everything together just as it told us to do, but once we hook it up to the radio, or iPod, nothing happens. No music plays either. What are we doing wrong????
tamlani1 year ago

hey plz help me out. i am using 5m led flex roll with 12v adapter. plz guide me how many transmitter would i need as i am using one TIP31C but it doesn't work...

dinox4 tamlani3 months ago

i also could only find Tip31C it seems it needs higher input to work, mabye 5 watts speaker amplifier to work properly in my case...

it's transistor not transmitter. And one tip31C is all you need. However if you're 5m LED flex roll requires more than 12V to light up then you're going to see no light. Also keep in mind that the volume on your stereo must be high enough for the transistor to read a voltage coming in.

bswt10 months ago

i have a setup where i have 400leds wired in set of 4 so, 100 a group, could the tip31 switch them? or the better question would be, whats the max switching current (amps) tip31? if is more than 4-5amps than I'm fine. well i do have 3 here with me, so if it works than ill report it here.

Hey I was wondering how you were hooking up your power source. I am trying to connect about 30 LEDs for the right audio cable and 30 LEDs for the left audio cable and plugging them into a small mP3 port. I obiviously need another power source so I am trying to stay low cost and recycling an outlet plug but I don't know how to hook it up. I have made a small version of this with an LED each for the right and left audio cables hooked up to a 9V and it works fine but I don't know how to make it bigger.

look at this website . . It is a LED series parallel array calculator .most leds use about 3 - 3.5v at 20ma. i like to use 12v for my power source, then just in put the amount of leds 30 for each side

when using the outlet plug, make sure it is DC and not AC. you can use a transformer to bring down the voltage to the right amount. now if you use one of the black wall transformer, on one of the wire wheres a white line going down, it is the negative. Im now one with words so if theres anything more you need ask

bswt bswt10 months ago

after doing some testing i've found that one tip31 can handle 100leds any more and the tip31 cant open well enough

RileyS1 bswt7 months ago

i used 300 leds and its not so bright how did u did u do it

if you are using 300 led then you should use 3 TIP31's
bswt RileyS17 months ago

i used 34 resistors total (33) 200ohm(1/4w) and (1) 470ohm (1/2w)

this only for 100 leds not 300

for 300 leds is would be (99) 200ohm(1/4w) and (3) 470ohm (1/2w)


there is alot more that i can't say here, i do have a schematic of 400leds

but i dont know how to uplead a file here and even if i did its a program file

so you would have to download the program. the schamatic is written in LTspice and its free

let me know if you would like the file, just tell me on where would like to be posted

o= led and r = resistor the first set is top to bottom then right to left

ooor ooor ooor

ooor ooor ooor

ooor ooor ooor

o. . . o . . .or

huyvu89 bswt10 months ago

how can we hear the music if the already plug the jack to the input sound?

rbeck_v huyvu899 months ago

use a 3.5mm audio splitter, plug the splitter into the music source, plug speakers/headphones into one side and the led cube into the other

Chris1107044 months ago
How does this work? The head phone jack plugs into what ? A phone if so how will it play the music the headphonejack silents the misic
cminton5 months ago

Would it be possible to wire together multiple boxes? If I wanted to build three light boxes of different colors, how would I hook them together to work with the same music?

tomikavagyok5 months ago

Hello ! I need some help , Im using BD243C transistor 6x 2V orange Led and 12 V dc power supply, but the leds are not flashing :/ i controlled everything and the circuit is okay. What to do now?

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