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Easy diy sound to light leds a.k.a music leds

Updated on March 20, 2010

My first hub

Hey there folks, this is my first hub. To begin with, i've selected a topic or rather tutorial that is of my speciality. Being a student of electronics engineering i have a knack for transistors and their applications and adding to that i love to play around with leds and try to décor my home, room, car, bike etc using leds.

Well, this tutorial deals with how to make leds dance(blink) to music from ur pc, i pod, walkman, tv, or any other audio source.

This is the very first diy project of mine and it is utterly easy and can be made by anyone. It doesn't require much electrical knowledge, just some basic skills!!!

So here we go!!!

The parts required

TIP31 (a,b or c) (will discuss what this is later)- 2 nos.

leds (whatever color u prefer, i suggest blue)- depends on u

3.5 mm-3.5 mm audio cable-1 nos.

a general purpose pcb or project board

a sheet of acrylic-a4 size

pls refer to images to see how these parts look

3.5 mm jack splitter-1 nos


these pins are looking at the tip from front the steel part is at the back.
these pins are looking at the tip from front the steel part is at the back.
these are connections on both ends of wire
these are connections on both ends of wire
the longer end is negative. this is the actual size compared to my first finger.
the longer end is negative. this is the actual size compared to my first finger.

Parts description

The tip 31 is a power amplifier which means it can withstand very high voltages like 50-100 volts without burning. Its amplification is low but it suits our purpose.

leds i.e light emmiting diodes emit light when a certain amount of voltage and current is applied (typically more than 2v and 20 milli amps)

3.5mm audio jack is a standard audio cable. if u have any other connectivity please let me know and i'll guide u through.

general purpose project board-is used to solder components together.

acrylic is used for finishing and decorative purposes which is left up to u i'll discuss my ideas at a later stage.

so this was a quick overview of the parts if u want any additional info pls let me know.

Here comes the pain!!!

Just kidding.... there's no pain in this project.

here's the circuit diagram showing the connections.

and here i am explaining the connections.

1. the 3.5 mm jack- how to find out which one is left , right and ground.

 strip any one side of jack and u'll find three wires (see the image!!)

now fetch a digital multimeter(aka dmm)(image pls!!) and follow these steps

  •  select the continuity mode in dmm
  • hold one probe against any one wire and the other on the tip, ring or sleeve of jack(refer image)
  • u should here a beep confirming that the wire and the part of the jack are connected.

now moving on.the left or right channel goes to the base of tip31, the ground goes to the emitter.

the wire from collector goes to the negative of the first led.

now for the leds pls read this carelully

  • there are 2 ways of connecting leds viz. series or parallel
  • series connection is the one shown in circuit i.e the positive of first goes to the negative of second and the +ve of 2nd goes to the -ve of 3rd and so on till the last +ve is connected to the positive of the battery.
  • we do not prefer this connection because it consumes more voltage i.e 3 v for each led i.e 12 v for 4 leds.
  • now the parallel connection- the wire from collector goes to the -ve of all leds simultaneously whereas the positive from battery goes to the +ve of all leds simultaeously.
  • the major advantage is that it consumes only 3 volts (min) and even 5 volts can be used to drive as many as 20 leds simultaneously.
  • now this modification was required because of the USB yeah right USB gives 5v output and can be used to drive the circuit or also a single 9 volt battery can be used (image) which makes it compact compared to 12v battery and the number of leds connected can be increased to our requirement.

Now there might be a confusion that leds can take a maximum of 3.5-4 volts after which they sort of burn off so can i apply 9 volts to all simultaneously....this is the reason why a power amplifier is used to handle higher voltages.

here comes the pain

the circuit
the circuit
jack stripped at one end
jack stripped at one end
the DMM
the DMM
pls zoom to see the continuity mode(the pointer is pointing at it)
pls zoom to see the continuity mode(the pointer is pointing at it)
9 v battery
9 v battery
battery connector
battery connector
description of jack
description of jack


now connect the jack that u have connected to the circuit as well to a splitter(image)

in the other hole connect the pc speaker cable/ or any speaker and put the splitter into the pc output.

so that u can listen to the music and see the leds dance to it simultaneously.

i have uploaded a video pls watch it.


so far this project can only blink leds to the music frm left or right channel from the jack.

my next hub will be about how to make a circuit that causes the leds to dance to left and right and believe me its awesome i've made it and its still under test... my next hub will have a video of the left right effect and a completely finished project.

So behold the led jukebox 2000.

the video(unfinished)


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    • profile image

      Hoho 6 years ago

      You can strip the thin wires with a small flame, the coating will receed.

      But you may still have to solder to them rather than a twist connection.

    • profile image

      Alex 6 years ago

      My jack wires are green red, and blue?

    • profile image

      beginner 6 years ago

      where can I find that type of audio cable? I've read that any pair of headphones should work but I cut a pair of thin earphones and there were just three different colored wires that were much too thin to strip. where can i find a jack that has thick enough wires to strip?

    • profile image

      mr.omniscient 7 years ago

      alright everyone its been quite a while but here are your answers!!

      1. if u are not getting enough luminition or brightness then u can pass the audio to tip 31 through an amplifier! laptops usually have low power output! just look up on common emmiter amplifier on Google u should get enough info.

      2. the tip is a very common amplifier u should get it anywhere! in Mumbai u will get it at lamington road!!

    • profile image

      Ole 7 years ago

      where i can get the tip31 ?

    • profile image

      Mutaz 7 years ago


      i have connected 8 blue leds in-parallel to the 5 volts directly from PC power supply...

      also did not find tip31 between some old electronic boards...but found the tip121 and it works fine...

      i mounted the 8 leds to my PC is cool

      see the image..

      how can i make the light more sensitive for lower sound volume ?

    • profile image

      aryan 7 years ago

      Its awesome!!!

      but iam facing a little problem.I use a laptop and when I connect this circuit and headphones the blub's wont glow to full brightness and its actually depending on sound.How ever when I only use the circuit with out any speakers or headphones everything goes..What should I do so that I could use both headphones and the circuit.

      I am using 3 LED's and a 9 volt source