Music Operated Dancing LEDs


ByJayant 137

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


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  • sushmitha's picture
    Mar 21, 2016

    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 ?

  • Abhishek's picture
    Mar 29, 2016

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

  • johnjem's picture
    Feb 10, 2017

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

  • swati's picture
    Jul 25, 2017

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

  • Yash gohar's picture
    Yash gohar
    Aug 05, 2018

    Check the polarity of mic and other component or may be your mic is not working

  • Sara's picture
    Apr 07, 2016

    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.

  • harsha's picture
    Apr 08, 2016

    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

  • Maddy's picture
    Apr 17, 2016

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

  • Sudhanva's picture
    Mar 09, 2017

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

  • Miki Mixer's picture
    Miki Mixer
    Oct 05, 2016

    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.,

  • Jody's picture
    Apr 26, 2016

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

  • Siva's picture
    Mar 23, 2018

    How it's working plz tell me give circuit diagram and with connections also ur circuit diagram plz tell me

  • Muhammad Zubair's picture
    Muhammad Zubair
    May 15, 2016

    can we use transister BC548 ?

  • Ann's picture
    May 19, 2016

    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.

  • Abhishek's picture
    May 28, 2016

    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.

  • Kenn's picture
    Feb 24, 2020

    It does not make any sense to have a HP filter  as the 'beat' is in the lower frequencies. Further a HP lowers sensitivity

  • suraj 's picture
    May 19, 2016

    who current through in transistor

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

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

  • Abhishek's picture
    May 28, 2016

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

  • WilliamMn's picture
    May 21, 2016

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

  • Anne 's picture
    Jun 23, 2016

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

  • Anuraag's picture
    Jun 29, 2016

    What's the function of R1?

  • Abhishek's picture
    Jul 09, 2016

    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.

  • Kenn's picture
    Feb 24, 2020

    R1 sets the voltage for the condenser mic. This type of mic requires a power  supply

  • gustavo's picture
    Jul 18, 2016

    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!

  • Bilal khan's picture
    Bilal khan
    Jul 25, 2016

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

  • ALISTER's picture
    Jul 29, 2016

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

  • Maddy's picture
    Aug 20, 2016

    This project will cost you under Rs 50 + Breadboard

  • Ohene's picture
    Aug 12, 2016

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

  • Maddy's picture
    Aug 20, 2016

    What do you means by "precise values" ?

  • chinchin's picture
    Sep 08, 2016

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

  • shiva 's picture
    Sep 12, 2016

    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

  • Aman's picture
    Sep 15, 2016

    can u plz provide the ckt digram

  • Jayanth's picture
    Sep 26, 2016

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

  • jane's picture
    Oct 03, 2016

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

  • Ranjith kotian's picture
    Ranjith kotian
    Oct 14, 2016

    What is the value of R2

  • vishwajeet 's picture
    Oct 14, 2016

    can I use 1watt leds fr dis ??

  • Ebenezer's picture
    Oct 18, 2016

    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

  • CLaire's picture
    Oct 21, 2016

    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?

  • T.sorin's picture
    Aug 21, 2018

    Hy CLaire ,I have the same problem with my circuit .. I designed a pcb board ... and all connection are good beacause how you say if i clap my hand the microphone sensing this , and for a few part of a second , leds flash. I don't know what's the problem ... have you solved this problem ? if anyone can help me with this problem I could offer him the pcb replacement (board) .

    Tank you a lot . All the best.

  • Kenn's picture
    Feb 24, 2020

    There are several design issues with this circuit;

    1)  insufficient gain - a single transistor can not provide enough gain for the transistors that drive the LEDs

    2_ the LED driving transistors are unbiased and so need at least 0.65V to turn-on

    3) a HP filter makes no sense as low frequenies have more 'power' and  the beat


    In your case it sounds (no pun intended) like it is "working" but you want the light extended.  A capacitor connected to Q1's Collector and Ground - say 10 uF - might help. Otherwise a 'pulse stretcher' circuit is needed.

  • Kenn's picture
    Feb 24, 2020

    There are several design issues with this circuit;

    1)  insufficient gain - a single transistor can not provide enough gain for the transistors that drive the LEDs

    2_ the LED driving transistors are unbiased and so need at least 0.65V to turn-on

    3) a HP filter makes no sense as low frequenies have more 'power' and  the beat


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

    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?

  • Mark's picture
    Oct 24, 2016

    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.

  • sachin's picture
    Oct 21, 2016

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

  • Mithun's picture
    Oct 26, 2016

    I wanna this experiment pdf

  • Raghav Taneja's picture
    Raghav Taneja
    Oct 31, 2016

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

  • Hadyan's picture
    Nov 01, 2016

    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?

  • Chandra Mouli's picture
    Chandra Mouli
    Nov 02, 2016

    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?

  • Abhishek's picture
    Dec 01, 2016

    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.

  • Walid's picture
    Nov 04, 2016

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

  • Rupam's picture
    Nov 21, 2016

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

  • Malik sufyan's picture
    Malik sufyan
    Nov 22, 2016

    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 ???

  • casper's picture
    Dec 07, 2016

    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

  • matt's picture
    Dec 08, 2016

    Can I use a 2N222 transistor

  • Praktan's picture
    Dec 10, 2016

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

  • vishal's picture
    Dec 14, 2016

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

  • Maddy's picture
    Dec 17, 2016

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

  • vishal's picture
    Jan 05, 2017

    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..?

  • Ayden's picture
    Dec 20, 2016

    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

  • Shehryar Hassan Khan 's picture
    Shehryar Hassan...
    Dec 28, 2016

    Kindly tell me about the working of transistors here

  • felawe's picture
    Jan 01, 2017

    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.

  • Maddy's picture
    Jan 28, 2017

    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.

  • Ahmed's picture
    Jan 06, 2017

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

  • Gaz's picture
    Jan 09, 2017

    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)

  • dhawal's picture
    Jan 20, 2017

    what are applications of dancing LEDs

  • Arjunakrishna's picture
    Jan 26, 2017

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

  • johnjem's picture
    Feb 09, 2017

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

  • G.Gunderson's picture
    Feb 13, 2017

    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?

  • Maddy's picture
    Mar 04, 2017

    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.

  • Maddy's picture
    Mar 04, 2017

    Yes you can use 3904 NPN transistor. 

  • Ronnie's picture
    Mar 03, 2017

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

  • Grae's picture
    Mar 06, 2017

    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...

  • Joe's picture
    Mar 09, 2017

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

  • Lef cram's picture
    Lef cram
    Mar 11, 2017

    OHHH yeah!!! it works

  • Ajay Rajput's picture
    Ajay Rajput
    Mar 19, 2017

    Which type of mic use


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