Introduction: Music Reactive LEDs

Picture of Music Reactive LEDs

Welcome to my Instructable! I decided to make my room a little better place and a bit more enjoyable.
That's where the idea of adding LEDs that flash with music came into my mind. I searched here in Instructables about "How to make a Sound Interactive LED", although there was only one instructable which really helped me out (here it is).

How my room looks like:

So, if you have watched the video embedded above, and you would like to create your own room with Music Interactive LEDs, continue to the next step to see what parts you will need in order to create this!

Excuse me for my English, I will try to describe everything with details so you can fully understand every single step!

Step 1: Parts for PCB

Picture of Parts for PCB
Parts for the PCB (Picture 1):

  • 1x Prototyping Board
  • 1x LM324 Op-Amp
  • 2x 100k resistors
  • 2x 5.1k resistors
  • 1x 100Ω resistor
  • 2x 1N4007 diodes

Use Picture 2 in order to create your circuit!

If you cannot understand schematics, I have attached a zip file which includes a PCB I created using Eagle and you can use (e.g
Oshpark) to order a PCB! The zip file also includes a schematic for the PCB and a text file which includes a parts list :)

Step 2: Parts for Installing the LEDs

Picture of Parts for Installing the LEDs

Parts for installing the LEDs:

1x Soldering Iron
1x Isolating Tape
1x Soldering Grease (cleans the tip of your soldering iron and makes cleaner connections!)
1x Tool to cut wires
1x Red Colored Wire (for any positive connections such as 12V IN and Audio IN)
1x Black Colored Wire (for any negative connection such as GROUND)

Step 3: Put Your LEDs in Place!

Picture of Put Your LEDs in Place!
  1. Think a nice place to put your LEDs!
  2. Calculate how many metres of LED strip you need.
  3. Cut and solder your LED strip.
  4. Put your LED strip in place and move to the next step to connect the LEDs, the power supply and the sound cable to the PCB!

Tip: Depending on how many metres of LED Strip you need, you can calculate how many Watt power supply you need to buy. For example, 1 metre of LED Strip needs 4.8W. I used 10 metres of LED Strip. That means I had to buy a 48W supply. Always buy a supply that can provide a little more Wattage just to be sure it will work!

Step 4: Connect the Sound Wire, the Power Supply and the Led Strip to the PCB

Picture of Connect the Sound Wire, the Power Supply and the Led Strip to the PCB

Step 5: Improving LEDs' Response by Cutting Unwanted Frequencies!

Picture of Improving LEDs' Response by Cutting Unwanted Frequencies!
Music includes many frequencies. The problem is that our PCB will take ANY frequency in order to light up the LEDs, which means that our LEDs will light with all music elements (Bass, Sounds, Kicks, Snares, Lyrics) and that is very very bad.

You will ask me.. "Why not adding a filter in the PCB that cuts some frequencies?" and that is a good question.

We can't simply put a frequency cutting filter in our PCB that cuts for example the Bass (LOW) frequencies, because many different music genres use different music elements in different frequencies, some examples are:

  • In House and Trap music we need to cut all LOW frequencies, reduce the MID frequencies and boost the HIGH frequencies (because we mainly want our LEDs to flash with the kick and snare).
  • In Psychedelic music we need to reduce the LOW frequencies , and cut the MID and the HIGH frequencies (because the psychedelic kick is mostly LOW frequency).

Personaly I have done a trick. I use Traktor and a MIDI console (that has its own soundcard).

  1. I load up a mixing software (like Traktor).
  2. I load the same song in Decks A and B.
  3. On Deck A I do not change anything (This Deck is outputing to my speakers).
  4. On Deck B I cut any frequencies I do not want to go to the PCB.
  5. I set the crossfader all the way to the Deck A, so only that deck is outputing to my speakers.
  6. I connect the PCB to the Headphones output of the MIDI console.
  7. I press the Headphones button on Deck B.
  8. I press PLAY in Deck A and then drag and drop the same song to the Deck B and they sync automatically at the exact same time.

In case you do not have a MIDI console I have created a 3 band EQ PCB that uses potentiometers to cut/boost LOW, MID and HIGH frequencies. I have included both board and schematic files in a zip file below!

Step 6: FAQ

Q: All ground wires and ground connections are connected together?
A: Yes! Except the ground from the LED Strip which is connected to PIN 2 of the TIP31 Transistor.

Q: My circuit doesn't work, did I do something wrong?
A: First make sure your LM324 is not fried. LM324 tends to fry immediately if you connect the power supply wrong.Also please send me a picture of your circuit so I can try to help you out with your connections.

Q: Can I use both 12/24 Volt LED Strips?
A: Of course, remember to add a LM7812 in order to supply the LM324 with 12V instead of 24V.

Q: I do have a 12V power supply, is it fully compatible?
A: It depends on how many metres of LED Strip you have installed. For example I installed 10 metres of LED Strip in my room. If my LED Strip needs 4.8W/meter , that means 10 metres need a 48W power supply. Always choose a little more Wattage power supply, I chose a 50W supply :)

Q: Can I ask another question?
A: Of course, please comment below and I will reply to you as soon as possible! :)

Step 7: My Custom Designed PCB!

Picture of My Custom Designed PCB!


damjan.mihelic.94 (author)2017-12-19

How can i control led's bightness in this project? With pwm or?

RollandE (author)2017-07-09

Stupid newbie question. On the printed circuit board where does the 12V input power go? I do not see any holes for the input power, only the 3 connectors for ouput power? also what is the specification on the single onboard led power indicator? a 2v 20ma led? or something different?

mikekousa (author)2016-12-29


I have a problem that the MUSIC REACTIVE LEDs BOARD can't share the same power supply(12 V DC) with the Audio Board. Need help on that. Anyone help please!

Thanks in advance!

PallabD (author)2016-10-03

Hi Orestis , in you pcb photo there are three connectors , what are they plz reply. Your curcuit seems to be the best one until soo far

PallabD (author)2016-09-21

Very cool n interesting project , I am planing to do it as I already installed led strips on wall and on my gaming desk (self made, self painted) , now I want sound activation on my all led strips but want to use different channels such as ( left audio controlls under desk led strip ,1mtr. Right audio coltrolls leds behind desk, and the woofer controlls the wall led.) But the problem is I am not getting the TIP31 anywhere , so want to know what are the alternatives of the same. There will be 3 separate circuits. Sorry for sush long post, I just want to share my idea.

Orestis Mokas (author)PallabD2016-09-22

Please have in mind that you will need to use filters to send the correct frequencies to each circuit!! For TIP31C you can actually use any transistor able to drive the volatge and the current you want! Please tell me some transistors you can find to advise you further!

PallabD (author)2016-09-21

Here are some pictures, soon I will change the blue leds with red

hollejd1 (author)2014-04-26

Hey, I love this Idea and I am planning on making one. Just so you know, you forgot to put the transistor on all of your parts lists. What are the white JST connectors you used on the OshPark PCB? I would like to use the same ones if I order a PCB from them.

Thank you!

Orestis Mokas (author)hollejd12014-07-01

Sorry for the late reply, I had final exam period on school.

The link above is the JST connectors you need for the PCB , you can easily find them in a local shop in your area. Remember its 1.25 pitch , 2 pin, through hole!

Have a nice day :)

hollejd1 (author)Orestis Mokas2015-08-29

Hey sorry I didn't realize you had responded to this. It ended working out fine because is built my own PCB. I made this with some RGB LEDs and made it so you could still control the colors. I had to substitute the tip31 with a tip2955 I believe but it was a bit dim on the output (maybe because of the RGB). To fix this (it was due to low current) I put 2 transistors in a darlington pair and it works wonderfully. If anyone else has that issue that may help. Great Instructable, it's one of my favorite projects I've made.

Orestis Mokas (author)hollejd12014-07-01

And thanks for noticing the missing part!

cryptcory made it! (author)2015-04-21

Thanks for the instructable. Everything's working great!

savdd (author)2015-04-14

How do I set it up with an RGB LED strip that has a controller and the functions on the controller still work?

savdd (author)savdd2015-04-14

While the LEDS are flashing to music?

frusology (author)2015-01-30

Hey Orestis! Nice Instructable :D

I'm a total newbie on this and I'm trying to pull this one off, however I'm not quite sure on how to solder this :( Do you think you can send me a pic of the PCB (not the custom made one, the regular one) from the coopery side so I can see how to make the proper connections?

Thank you and keep the good job!

meraz.rahman (author)2015-01-10

is there any substitute of LF351N ?

meraz.rahman (author)2015-01-06

Can i use tip35c instead of tip31 ?

Yes of course ! :)

TIP35C can just handle more current than TIP31C

tamlani (author)2015-01-06

need help..!!! NEWBIE

well every thing is clear in schematic except for few...

where am i going too wire LED +ve and -ne? & where am i going too wire Adapter +ve and -ne?

there are 5 grounds in schematic as shown in circuit image if anyone can label them as which will be use for led or adapter, it will be really helpful.


silasgreave (author)2014-11-25

hey i made it finally !!!!!! will you please draw the circuit diagram of the equalizer , then it will be very helpfull to me....

aka619ASH (author)silasgreave2014-11-25

Hey Buddy, I noticed your message that you build your circuit and I have been trying to build mine too and I build it but when I play music the dim effect is negligible during beats change. Can you help me here. I can post video sample too.

silasgreave (author)aka619ASH2014-11-25

just put a potentiometer on the input signal. but a we need a equalizer to do it well.

aka619ASH (author)2014-07-01

I need some help to fix my circuit, I build it but when connected to 12 V the led is constantly on.

I used the following:

1 TIP 31

2 5.1k resistor

2 100k resistor

1 100 resistor

2 IN 4004 diodes

1 LM324 quad opamp

Orestis Mokas (author)aka619ASH2014-07-01

Hey there, can I have a picture of your board (up layer , down layer) ? Are your diodes connected right? If you connect the audio jack to a device and play music what happens?

aka619ASH (author)Orestis Mokas2014-07-02

Hi Orestis,

Here are the pictures, let me know if you want me to post more pictures. Nothing is happening when I connect the audio to the jack, once the power is supplied the leds are constantly on no matter the audio is connected or not, they do not react to music. The pics are around 4000 px, so zooming in should work.

Orestis Mokas (author)aka619ASH2014-07-02

Can you take the wire and connect it to the other side like in the picture? I had a weird jack in the past that confused me about the connection.

aka619ASH (author)Orestis Mokas2014-07-02

Tried that too noting happened. One thing when I plug in the power cable the led is on. Even if I remove the complete audio input setup it is still on. BTW, I followed your work and this guys work,

Orestis Mokas (author)aka619ASH2014-07-03

Maybe you have got a bad LM324, there are many clones of it around. You can buy the premade pcbs from oshpark though and use a DIP14 socket to be able to change LM324 because they are also easy to fry (I burned about 10 while I was first building this circuit).

By the way the exact same schematic was combined with an equaliser one and it works amazing, I added a project box and the result is amazing :D

aka619ASH (author)Orestis Mokas2014-07-04

Can you send me a specific link to osh park. SO if I am right, I will be buying the PCB that you created right? Also do i need to place the resistors and other components in the pcb. ANother thing I chnaged the LM324 but same result and I remade the circuit, could it be because of the diode I am using? You suggested to use IN 4007 but I am using In 4004.

samalert (author)2013-12-05

I have problems understanding the connection circuit so i use my visual power to build one now in currently in your ible i am not able to figure out the circuit too as usual so i try to look at your physical connections if you wouldnt mind please post an upside down picture of your connection so it will be somewhat intelligible for me.

Orestis Mokas (author)samalert2013-12-05

Here you go!
I added some notes, if you can't see a connection, I will also upload a clean picture of the PCB upside down too.

Blue = LM324N pin numbers
Yellow = Resistor/Diode names and values
Red = Where a resistor/diode connects to

I will also update my instructable with the PCB I designed! I am sure you will like it! :D

can you upload it again please.. The link is not found. Thanks!

knex-guns-4live (author)2014-02-03

thanks for this clear explanation! i have seen the other 1 but this is much better!
Could you please explain how i could connect a RGB led strip to this?
I am moving houses and i wanted a project to work on for my new room. :D

by the way all the resistor values on the schematic I posted in the comment below are all 100Ohm!

thanks for the quick answer! (My name is made like 7 years ago so i was pretty young :p so don't take that to serious )
I think that i got the second option. here is a link:
somewhere in march i am moving houses so if i need your help i will PM you.
thanks for the support on this project because its a bit hard for me to understand your schematics.
Have a great time and i hope you keep making these projects!

I am not goot at schematics, I have just started to make PCBs. I will make a ready PCB with RGB Control because I have already done this. Here is a video :

I will send you the final PCB once its ready, you will only have to solder the pins, nothing difficult :D

(im the same guy with a other name)
But the problem is that i don't have a arduino board, or is it not needed?
Right no i am thinking this:

-------------------------------------------------R+ -------------------------------------------------G+


Soldering is no problem.
One think i am worried about is the included RGB controller.
wont the controller be confused if it gets a non regular signal?
I mean that if the led controller that you made only lets power go flow if the TIP31 transistor recieves as signal, that the Voltage is not stable for the RGB controller?

Actually you can just use different power supplies or the same if you want. Connect everything normally BUT you will have to cut the ground OUT from the LED Controller and connect it to TIP31 Emmiter and then connect the LED Strip's ground to the Collector. Easy and simple. Actually the strength of the audio signal is connecting the Emmiter and the Collector when needed and this is how the effect is done!

You're welcome. There are many ways to do this because there are many types of RGB LED Strips.

To do this with Digital RGB LED Strip just take the ground and connect it like I did with my normal LED strip. (to the Collector of the transistor on the PCB).

To do this with an Analogue RGB LED Strip is a bit more complicated. There are two types of Analogue RGB LED Strip:

1) One type has a one positive (V+) connection and the remaining ones (R , G and B) are the negative (Ground) connections. To do this with this type you must get 3 (or 4) TIP31 transistors and follow this schematic in order to be able to change colors from an arduino.

2)Second type has a negative (Ground) connection and the remaining ones (R , G and B) are the positive (V+) connections. To do this with this type you must just connect the negative connection to the Collector on the transistor on the PCB (the ground output for the LEDs).

Sorry for my english, If I didn't explain them well, once you get your new RGB LED Strip just PM me and I will help you via Skype or any service. 

Thanks for your words!

Slashmaster (author)2014-02-01

This is awesome, can we get a rough cost estimate?

Thank you! What do you mean by rough cost estimate? I am building a smaller version of this PCB, it gets as low as 2-3$ per PCB! You can order LM324 for a small price (I got 30 at about 0.30 euro each). Resistors are also cheap. So are LED Strips! You can find LED Strips for a small price on ebay :D

jthunder2 (author)2014-01-06

That PCB you made looks awesome! What company did you use to make that, and did you order multiple? Or did you make it at home?

Orestis Mokas (author)jthunder22014-01-06

Thank you very much! I designed it with Eagle and then used OshPark to order them :)

With OshPark the minimum is 3 PCBs.

quantya (author)2013-11-27

Hi, very nice project!!! My question is if I can install a microphone, instead the channel wire. Thank you.

Orestis Mokas (author)quantya2013-11-27

You can modify the circuit to be like this:

If you need any help with this you can contact me ! :D

quantya (author)Orestis Mokas2013-11-27

ok thank you very much!!!

Orestis Mokas (author)quantya2013-11-27

You're welcome!

m0nst3rsk8r (author)2013-11-26

can you use different colors

Of course you can ! :)
You can choose any color LED Strip, even RGB!

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