Music Reactive LEDs





Introduction: 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

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

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!

  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

Step 5: 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!



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We have a be nice policy.
Please be positive and constructive.




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

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?


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!

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

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.

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!

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


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!

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.