Music Operated Dancing LEDs

You must have seen the Disco Lights or DJ lights, which Turn ON and OFF according to the beats of the music. These lights glow according to the length and pitch (volume) of music beats, basically these are designed to pick the high intensity sound like Bass sound. So these lights follow the high pitch beats in music like drum beats, and Turn ON and OFF according to music pattern. However the sensitivity of the circuit can be increased to pick the low notes too.


Previously we have built Dancing LEDs, which just follow a set pattern and we can only control the speed. Now we are taking this to next level, i.e. Music Operated Dancing LEDs, in which LEDs will flash according to music, just like Disco light, as discussed above. This Musical LEDs circuit is based on transistor BC547. This circuit is very simple and easy to build, it just requires few basic components and it looks very cool.



  • Condenser Mic
  • 5- NPN Transistor BC547
  • Resistors- 10k (2), 1k (4), 1M (1)
  • Ceramic Capacitor 100nF
  • 4 – LEDs
  • 9v Battery
  • Breadboard and connecting wires


Working Explanation:

In this Simple LED Music Light Circuit, condenser mic picks up the sound signals and converts them into voltage levels. These voltage signals are further fed into R-C filter or HIGH PASS filter (R2 and C1), to eliminate the noise from the sound. Further a NPN transistor (Q1- BC547) is used to amplify the signals, from the High Pass filter. Then finally these music signals are given to the array of four transistors. Transistor in this array works as amplifier, and glows the four LEDs according to the sound pattern. This generates a very interesting sequence of dancing LEDs which follows the beats as per their intensity or pitch. We can also add more LEDs with transistor to make it cooler.


BC547 based led music light circuit diagram


We can adjust the sensitivity of MIC by changing the value of R2 and C1, by using the formula for R-C filter:

 F = 1/ (2πRC)

F is the cut off frequency, means filter only allow frequency above than F. It can be easily deduced that more the value of RC, less the cut off frequency and higher the sensitivity of MIC. And higher the sensitive of circuit means MIC can pick low volume sounds, hence LEDs can glow on low pitch music also. So by adjusting its sensitivity we can make it less sensitive to reacts only on high note beats or we can also make it more sensitive to react on every little beat in the music. Here we have set its sensitivity at moderate level.


Condenser Mic should be connected properly in the circuit, according to its polarity. To determine the polarity of MIC one should look at mic terminals, the terminal which have three soldering lines, is the negative terminal.


Transistor BC547 is a NPN transistor, which is used as a Amplifier here. NPN transistor acts as a open switch when there is no voltage applied on its Base (B) and it acts as closed switch when these is some voltage at its base. Generally 0.7 volt is enough to get it fully conducted. 

Transistor BC547


Comments (121)

  • sushmitha's picture

    what s the role of the transistor here in the circuit ? y we need it ? wat s d main role in tis circuit ?other than transistor can any other element be replaced ?

    Mar 21, 2016
  • Abhishek's picture

    Transistor is used as Amplifier here, please learn more about Transistor.

    Mar 29, 2016
  • johnjem's picture

    im trying to get mine to work and have done all the hook ups and it still isnt workign. please help

    Feb 10, 2017
  • swati's picture

    I am completed all this circuit connection, but can't work it.
    plz help.

    Jul 25, 2017
  • Sara's picture

    In this circuit transistor acts as switch. however, I use 220ohms resistor instead of 1kohms and I added another resistor(also 220ohms) between the collector of Q1 and base of Q2, then it works.

    Apr 07, 2016
  • harsha's picture

    I did the same connections as above but the LEDs are glowing without music too.Can anyone help out?.
    I want to know how connections are done. Especially the bases of transistor.
    Please reply fast

    Apr 08, 2016
  • Maddy's picture

    Reduce the value of 1 M resistor or use variable resistor instead and adjust the sensitivity.

    Apr 17, 2016
  • Sudhanva's picture

    I reduced 1M ohm resistor to 1Kohm then too the leds r glowing on its own ...Any solution???

    Mar 09, 2017
  • Miki Mixer's picture
    Miki Mixer

    as u r connected Microphone The Small Audio Inputs Are Also Causing THe LED Action.Insted Of Mic U Can Also Add A Audio Input Signal For A Perfact Action.,

    Oct 05, 2016
  • Jody's picture

    The circuit worked perfectly :) , but i want to know what will happen if we replaced the MIC with a high voltage signal.

    Apr 26, 2016
  • Maddy's picture

    Not getting your question.

    May 17, 2016
  • Muhammad Zubair's picture
    Muhammad Zubair

    can we use transister BC548 ?

    May 15, 2016
  • Ann's picture

    This circuit is really great and cool. I just wanna know if it is ok to use low pass filter instead of high pass filter to make the LEDs blink on and off to the bass.

    May 19, 2016
  • Abhishek's picture

    No, you should only use High pass filter. Low pass filter is opposite of High pass. High pass filter allow signal above the selected cut off frequency, whereas Low pass filter allows signal below than cut off frequency.

    May 28, 2016
  • suraj 's picture

    who current through in transistor

    May 19, 2016
  • Muhammad Zubair's picture
    Muhammad Zubair

    if i want to increase no of led's ......wht chnges comes in circuit ? should i have to increase voltage ?

    May 19, 2016
  • Abhishek's picture

    For a 9v battery you can glow up to 25-30 LEDs, more the LEDs, faster will Battery run out.

    May 28, 2016
  • WilliamMn's picture

    Appreciate you sharing, great forum.Much thanks again. Winley

    May 21, 2016
  • Anne 's picture

    I was just wondering if it is ok to use other types of non-electrolytic capacitor instead of ceramic capacitor? Thank you

    Jun 23, 2016
  • Anuraag's picture

    What's the function of R1?

    Jun 29, 2016
  • Abhishek's picture

    Resistor R1 (10k) has been used as a Pull up resistor to connect Condenser mic to the positive supply voltage, to provide the power to the mic.

    Jul 09, 2016
  • gustavo's picture

    hi! Hey I was wondering if instead a mic I could use a jack, a mono one of course....also, if I wanna turn brighter leds ill just lower the 1k resistors, no?
    Thanks, nice project btw!

    Jul 18, 2016
  • Bilal khan's picture
    Bilal khan

    which type of mic we can used , if we are not using condensor mic?

    Jul 25, 2016
  • ALISTER's picture

    what is the total cost of this ?
    could you propose me a circuit total cost under Rs.50.

    Jul 29, 2016
  • Maddy's picture

    This project will cost you under Rs 50 + Breadboard

    Aug 20, 2016
  • Ohene's picture

    Please i want to know the precise values of resistor R1-R7 please

    Aug 12, 2016
  • Maddy's picture

    What do you means by "precise values" ?

    Aug 20, 2016
  • chinchin's picture

    can you teach us how to make this kind of project.steps please

    Sep 08, 2016
  • shiva 's picture

    can you tell me what's the role of BC 547 npn transistor in the circuit and how it is happing I.e, the LEDs r
    glowing in presence of music
    what actually happening when supply voltage is given to the circuit

    Sep 12, 2016
  • Aman's picture

    can u plz provide the ckt digram

    Sep 15, 2016
  • Jayanth's picture

    hai , can we extend the circuit , i mean can we increase the no of leds used in the circuit and driving capacity

    Sep 26, 2016
  • jane's picture

    Could you give me the spec for the mic or ideally a good place to source them

    Oct 03, 2016
  • Ranjith kotian's picture
    Ranjith kotian

    What is the value of R2

    Oct 14, 2016
  • vishwajeet 's picture

    can I use 1watt leds fr dis ??

    Oct 14, 2016
  • Ebenezer's picture

    A great site and an interesting Q&A. I can't say more than to say thanks..
    I have gotten all the questions.
    I love the comprehensive explanation from the cct analysis.
    Kudos to you..
    I have bookmark you already

    Oct 18, 2016
  • CLaire's picture

    We have built the circuit but the leds are unresponsive to music - they flash if we clap our hands beside the mic but otherwise nothing. Circuit has been built using exact components described and follows exactly the same layout. Any suggestions?

    Oct 21, 2016
  • Siti Nadzirah 's picture
    Siti Nadzirah

    I want to make the circuit more simple because i want to demonstrate in front of primary school student. If I reduce the number of led its will effect the circuit or not?

    Oct 21, 2016
  • Mark's picture

    Should be no problem. Leds with Resistor and Transistor are set in parallel, therefore you can add or remove as you want.
    Led1 + Q2 + R4 = 1 group
    Led2 + Q3 + R5 = 1 group
    Led3 + Q4 + R6 = 1 group
    Led4 + Q5 + R7 = 1 group

    Just make sure you add or remove a complete group when adding or removing leds.

    Oct 24, 2016
  • sachin's picture

    please explain how to make connection in this circuit please teach me any one

    Oct 21, 2016
  • Mithun's picture

    I wanna this experiment pdf

    Oct 26, 2016
  • Raghav Taneja's picture
    Raghav Taneja

    I did the same thing except instead of 1M ohm I used 1.3 M ohm but my output is not coming.

    Oct 31, 2016
  • Hadyan's picture

    What if there is no R1 and the capasitor connected to the ground and the mic directly connected to the battery? Is this circuit still work?

    Nov 01, 2016
  • Chandra Mouli's picture
    Chandra Mouli

    I have exactly represented the circuit like in the ckt diagram. But The LED's are always on. If i switch the polarity of the LEDS. Then they are OFF, but not recognizing the music input from the mic. (I have used a 1.3M ohm resistor instead of 1M and 104nF capacitor). This shouldn't alter the circuit by a lot should it?

    Nov 02, 2016
  • Abhishek's picture

    Resistor value is crucial for the circuit work, increasing the resistor value to 1.3M made the circuit highly sensitive and the LEDs will be on even with the sound of air. You can reduce the resistor value but then it will be less sensitive to lower notes of music.

    Dec 01, 2016
  • Walid's picture

    can I add a water dancing circuit , so both circuits work together by using music

    Nov 04, 2016
  • Rupam's picture

    Hey.....if i use a 5v battery then what should i do....

    Nov 21, 2016
  • Malik sufyan's picture
    Malik sufyan

    I did the same as above ......but led's blink when we touch wires ...but not blink with music.... what i do can any one help me ???

    Nov 22, 2016
  • casper's picture

    i want to know what the kind of mic is used
    I want, I work for this circuit simulation program orcad do not know What kind of MIC is used

    Dec 07, 2016
  • matt's picture

    Can I use a 2N222 transistor

    Dec 08, 2016
  • Praktan's picture

    Plz reply How to use this ckt for 230 volt ac supply.......

    Dec 10, 2016
  • vishal's picture

    What is the maximum no. of led's i can use for a supply of 12v...
    i might need 100 leds..

    Dec 14, 2016
  • Maddy's picture

    Driving 100 LEDs need approx 2A current (20mA per LED), so you also need to change transistors and other components accordingly.

    Dec 17, 2016
  • vishal's picture

    im trying to do this one with 100 leds..
    if possible, can u please tell me the specifications of transistors and other components used for this..?

    Jan 05, 2017
  • Ayden's picture

    Ive got all the LEDs hooked up right and everything else i think is correct yet the mic wont cause the leds to do anything but if i remove the transistor from ground all the LEDs light up bright

    Dec 20, 2016
  • Shehryar Hassan Khan 's picture
    Shehryar Hassan...

    Kindly tell me about the working of transistors here

    Dec 28, 2016
  • felawe's picture

    LED turns on even no music was played. Tried lowering the 1M ohm resistor value but the same happens. Even tried to remove it completely and it still doesn't work. Can anyone kindly explain whats happening to me please. Thank you.

    Jan 01, 2017
  • Maddy's picture

    Put the circuit exactly as shown in the circuit diagram, it will work for sure. Further try replacing the Mic and other components, may be some faulty component is there.

    Jan 28, 2017
  • Ahmed's picture

    can this circuit be modified to make a audio level indicator??

    Jan 06, 2017
  • Gaz's picture

    Awesome stuff, put together as directed and works awesome... well done... I am thinking on an improvement and adding four seperate transistors on different frequency levels to run four different colours (perhaps for an rgb light strip with required extra circuitry)

    Jan 09, 2017
  • dhawal's picture

    what are applications of dancing LEDs

    Jan 20, 2017
  • Arjunakrishna's picture

    What type of LED's Used in this circuit.plz reply ,Is not worked

    Jan 26, 2017
  • johnjem's picture

    im trying to hit 740Hz or F4# . will set up be able to work this?

    Feb 09, 2017
  • G.Gunderson's picture

    I understand the amount of ohms needed for the resistors but I'm seeing a lot of variation in the ppm values and percents and all that jazz. Do these values need to be the same for all the resistors, or how do I know what ones to buy when building this circuit?

    Feb 13, 2017
  • Maddy's picture

    Value of resistor should be the same, however value of R2 decides the sensitivity of the circuit, more the value of R2 means more the sensitivity to react on low sounds.

    Mar 04, 2017
  • Maddy's picture

    Yes you can use 3904 NPN transistor. 

    Mar 04, 2017
  • Ronnie's picture

    I did as you instructed but when you connect to battery for it just light without music sound
    What can I do please

    Mar 03, 2017
  • Maddy's picture

    Try lowering the value of R2.

    Mar 04, 2017
  • Grae's picture

    This circuit is working above certain frequency but what to do if I want to set upper frequency too simultaneously in same circuit? Please reply fast...

    Mar 06, 2017
  • Joe's picture

    Hi, I just want to know if the resistors here are 1/4 watts or 1/2 watts?

    Mar 09, 2017
  • Lef cram's picture
    Lef cram

    OHHH yeah!!! it works

    Mar 11, 2017
  • Ajay Rajput's picture
    Ajay Rajput

    Which type of mic use

    Mar 19, 2017
  • Suraj's picture

    Hey Maddy.. Ur project is awsm..
    I hve one question. This cct is on DC if I wan to connect ac current then?? Of 230v..

    Mar 18, 2017
  • Ritvick's picture

    Can you please provide me a circuit that uses sound as an input but works on NE555 timer.
    As for my project i need to make a flash led circuit using above two technologies.

    Mar 21, 2017
  • Dean's picture

    Hey Maddy, i really love your project, its one amazing piece..... I've been trying to make little changes to mine but i've got no idea how to replace the mic with a speaker and audio jack :(... I hope you can show it on a circuit diagram... Thanks for understanding. :)

    Mar 21, 2017
  • Harshith's picture

    All the LEDs are starts glowing when battery is connected i put the circuit same as shown can any one help i didn't even connected the mic so that the mic is absorbing very little sounds

    Mar 22, 2017
  • jamezz's picture

    I learned that a condenser internally has a transducer... Please explain it and how transducer works also tell me about transistor.. In which mode it is here?

    Mar 29, 2017


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