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!

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This is the schematic for what I did. If you use a computer power supply cable, you will have lots of current to spare. In theory, you could put a few hundred led's into an array of 6 series led's in many parallel chains. Does that make sense?
sweetie039 months ago
Hi, awesome work guys... i just started learning these things and dis is quite fun ..can i use a bc547 npn transistor in place of tpi31 ?

try it and see what happens. They are all NPN transistors. Just make sure you plug it in correctly.

tamlani6 months 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...

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.

I've having some troubles with this. When I connect my LED to the farthest left pin of the TIP31 I get some constant light but when I connect it to the middle pin nothing happens. I'm using the headphone part from old apple earbuds if that makes a difference.
I'm having the same issue. Constant light on either side pin and no light on the middle pin. I thought maybe it was the transistor, but I changed it out for a new TIP31 with the same results. My schematic is slightly different. Any thoughts on why this might be happening?
tamlani dseter6 months ago

heyy did u find any thng good relating to your problem??

i am having the same problem... i am using 5m led flex roll and 1 transmitter TIP31C and a 12v power suply...plz help me out if u know how to deal with that. thanks

are u sure your looking at the front of the tip 31 when connecting the wires. you might have the right confused with the left causing problems.
xangel7 months ago

Hello! I am new here and.... I have a question about this project: What should I do to make it work with light bulbs at 220V ? :D
Thank you!

MarioNL xangel6 months ago

Search "Relay" on google. I wouldn't do it as a beginner though, because you will be working with high voltages. Try some smaller projects first.

csshandy6 months ago

if you use lets say for example a car stereo and try and connect it to a high or low input of one of the channels it can cause some problems because the stereo is using the 12 volt car battery and the tip31 is aswell it can create a short circuit because the sound out of a stereo is A.C meaning the wire on the ground side can shift from low to high causing a short circuit the only way I can think of around this is adding a 1k resistor between the power for the tip31 so that it stops this however haven't tested it, this is my understanding of it so if anyone has anymore input on this feel free to give advice I will test this theory out tomorrow and post back.

bitone11 months ago
I have put 3 leds with a 9v adapter, and when i plug it into my pc i have to turn my volume to 200% to get around 40% of led's brightness. LED's shine bright when tip31 is not present. Any help? (I've checked every single conection,everything appears to be in order but it wont light up bright)
etkinsr bitone7 months ago

I'm having a similar issue. The LED I'm using to test the circuit (no idea what the voltage required is, but 5V from Arduino with a resistor in series) lights up when the transistor has no voltage on the gate, which doesn't make any sense - should be no current flowing. The audio signal doesn't control the transistor either. Any ideas?

nwalawalkar7 months ago
just thinking of what else can we do with this using a mcu like rasberry pi or arduino ;-)
nwalawalkar7 months ago
purely neat clean and simple. all the best
putod7 months ago

Is there a particular kind of electrical wire that I need? Or would any old wire do?

ngreen117 months ago
Circuit worked well but I connected the input onto the wires for my sub and if I turn it up just a but, my receiver shuts down into protect mode. Any idea why?
jbreese998 months ago

How do I get this to react more with the mid/upper? I have 3 LED's and I want 1 to be bass and the other to do the uppers.

asimobot8 months ago
I made a circuit with 3 green 5mm leds, with a 6V power supply and a resistor just to see if this works, then I was going to put it on a bigger circuit later with more leds, I also tried it with a 12V power supply and the resistor is 330ohm 1/4 watt. The LED's dont blink they just stay still no blinking and no other reaction. What should I do?
GeckoFrog8 months ago
I have just made this circuit using 6, 2.2v yellow led's, a 12v power supply, and a resistor. It works, but the lights take heaps of sound to stimulate them, only pulsing on the louder beats- why is this, and how can I overcome this problem?
-the resistor packet reads '0.5W metal film 270R 1%'
ajolivolo8 months ago
ok so i hooked up everything as instructed, but im having issues.

the headphone jack wires are very small and each ear has a charged wire along with a ground, so 4 wires not 3. tried hooking up one and one of the right ear piece and no luck there. tried adding a resistor, no good.

real issue is that they stay on 100% even without the headphone portion soldered on, just the tip31 and power source.
Taha998 months ago
Do I have to use Resistors with the LEDs?
yes u will have to in order to save leds from burning.
Thnxs alot , but if the LEDs demand 3v and i use a 12v adapter and i use 4 leds, then i still have to use resistors?
yw :) yes, resistor acts as a current limiting device. (also check for the colour of led u are using,drop varies according to the colour)
this is with series connection but with parallel resistor value differs according to omhs law.
Now i understand the whole stuff, Thanks again.
jhirsch29 months ago
Check out my version of this. My box has over 7 different colors and multiple functions. NO NEED FOR AN AUDIO INPUT. It works off the sound waves in the environment. All you have to do is plug into the wall. Fully controlled via remote.  Check the link below to see my project and a video!
cbrown839 months ago
Hi, I've just built this circuit and it works perfectly, however I have 3 leds which are really bright and 7 that aren't as bright. I'm using 10 leds in parallel each with its own resistor. Which is hooked up to a 12v 300mA power supply. I've done some calculations and have ordered a 6.2 ohm resistor to go before the leds to reduce the current. R= (Vs-Vf) / I. My supply voltage is 13.41, forward voltage is 12V and the current is 0.25A. Am I doing anything wrong? If so please help
kodagames9 months ago
Are you plugging the 3.5 jack headphone cable into a radio? and would it be possible to do this without directly plugging it into a computer/radio?
I'm working on something really similar that uses bluetooth, and has built in speakers. You won't have to do anything but open an app on your phone and jam.
I am trying to use 2 LED strips to get a stereo effect. I am using a potentiometer for each strip so that I can adjust the power or signal going to each LED strip, so that when I have the volume high I can adjust the sensitivity on the music box so that the LED produce a light that goes with the music better. I will reply when its good to go.
How is this going? I made mine in stereo pretty easily using two transistors, but I didn't think to use potentiometers.
sparksnflames11 months ago
I've found heavy duty scotch-brite pads(the green ones with the yellow sponge on one side) to work really well at frosting strips of LEDs (or LEDs mounted to circuit boards) they are soft enough that they don't break the LED leads, but abrasive enough that they scratch the surface of the led as well if not better than an emery cloth...
This tip helped me a lot! I used sandpaper at first but definitely scuffed them too much. The pads did the trick. Great tip!
Newtonium9 months ago
You could put a speaker in series with the LED's and headphone cable, hide it round the back or something, and listen to the music if your computer won't let you output speaker/headphone at the same time.
Build the speaker into the box. I'm working on another version that does this. It's pretty easy, you could even take apart some cheap computer speakers and use those since they have the built in power. You'd have to figure out how much juice to send to them but that shouldn't be hard since most of them have the voltage and current input on the power cord.
jsalas1010 months ago
I just built this and everything was working great, for about 10 minutes. Then my leds burnt out. I had 3 leds and a 9v battery. What do I need to change to make it last?
xenkenny jsalas1010 months ago
What color LEDs did you use? Different colors tend to have different voltage capabilities.

Example: Red LEDs usually use ~2V. If you used red LEDs, you will have an excess 3 volts on your circuit, so you needed to use a resistor to dissipate the last 3V.

What's nice about having an adapter is that is tells you the output current. Knowing the current allows you to find out what size resistor to use. If your battery ouput 200mA like OP's adapter, then the resistor you'd need to add to the end of your circuit would be 15 ohms. (Ohm's Law)
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