Small Loudspeaker for Computer or Cell Phone


ByJayant 28

Audio Amplifier: Small Loudspeaker for Computer or Cell Phone

Small Loudspeaker is a fun project to do, you can connect it to your Cellphone or Laptop through a 3.5mm audio jack and can enjoy your own loudspeaker. You can also connect it to any device which has a 3.5 mm audio output, like TV, music player, video games etc. We have used LM386 IC to amplify sound, with a few external components.


LM386 is a low voltage audio amplifier and frequently used in battery powered music devices like radios, guitars, toys etc. The gain range is 20 to 200, gain is internally set to 20 (without using external component) but can be increased to 200 by using resistor and capacitor between PIN 1 and 8, or just with a capacitor. Voltage gain simply means that Voltage out is 200 times the Voltage IN. LM386 has a wide supply voltage range 4-12v. Below is the Pin diagram of LM386:

LM386 Pinout

Pin description of LM386 along with the functions of external components used for amplification:

PIN 1 and 8: These are the gain control PINs, internally the gain is set to 20 but it can be increased up to 200 by using a capacitor between PIN 1 and 8. We have used 10uF capacitor C1 to get the highest gain i.e. 200. Gain can be adjusted to any value between 20 to 200 by using proper capacitor.

Pin 2 and 3: These are the input PINs for sound signals. Pin 2 is the negative input terminal, connected to the ground. Pin 3 is the positive input terminal, in which sound signal is fed to be amplified. We have connected one terminal of 3.5 audio jack to this input PIN 3 and the other terminal to Ground. 3.5 mm Pin is further connected to the Laptop’s audio jack.

3.5 mm stereo audio jack is found in mostly headphones, there are generally two types 3.5 mm audio Jack, TRS (TIP RING SLEEVE) and TRRS (TIP RING RING SLEEVE). In TRRS one extra terminal is generally for Microphone. We have used TRS audio jack here and soldered two wire to it, one to Ground (Sleeve) and other to Right audio (Ring) . You can understand by below images:

  TRS and TRSS Audio Plug

Pin 4 and 6: These are the power supply Pins of IC, Pin 6 for is +Vcc and Pin 4 is Ground. The circuit can be powered with voltage between 5-12v.

Pin 5: This is the output PIN, from which we get the amplified sound signal.

The output signal has both AC and DC component, and DC component is undesirable and can’t be fed to Speaker. So to remove this DC component, a capacitor C2 of 220uF has been used.

Along with this capacitor, a filter circuit of Capacitor C3 (.05uF) and resistor R1 (10k) has been used at the output PIN 5. This filter also called the “Zobel network”, this electronic filter is used to remove the sudden High frequency oscillations or noise.

Pin 7: This is the bypass terminal. It can be left open or can be grounded using a capacitor for stability.



  • IC LM386
  • 3.5 mm audio Jack
  • Speaker 8ohm
  • Capacitors- 220uF, 10uF (two), 0.05uF
  • Resistor- 10k
  • Battery 5-12v


Circuit Diagram and Explanation

Small Loudspeaker Circuit Diagram

I have cut the male to male 3.5 mm audio jack and solder two wires, but one should a female 3.5 mm audio jack for bread board. And connect one end of male to male audio jack to female audio jack and other end to computer.


This circuit is quite similar to my previous circuit “LM386 Based Audio Amplifier Circuit”, we just replaced the Condenser Mic with the 3.5 mm audio jack to provide the input sound. Also potentiometer has been removed, because there is already a sound control in computer’s Music player.


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  • Lallan Prasad's picture
    Lallan Prasad
    Jan 02, 2016

    I want do this project

  • Bhem's picture
    Feb 06, 2016

    Do you have the computations on how you arrive to those values of capacitors and the resistor?

  • Maddy's picture
    Feb 08, 2016

    Check the datasheet of LM386, these are the standard values to get the Gain of 200. We don't need to connect any external components to get the gain of 20.

  • lee's picture
    May 03, 2016

    where should the positive and negative terminal connect...

  • rahat hussain 's picture
    rahat hussain
    May 03, 2016

    need info about Power Rating of capacitors mentioned ???

  • Abhishek's picture
    May 28, 2016

    Any normal capacitor should work. 10uF caps are of 63v and 220uF is of 25v.

  • jitesh's picture
    May 18, 2016

    ic 810 audio and lm386 audio campers are the which is the best tell me please

  • Leo Cheng's picture
    Leo Cheng
    May 28, 2016

    Hello Jayant . I followed your steps, and everything seemed OK. My audio is from raspberry pi A+ 3.5mm jack, but the noise is very loud. Could you give me any suggestion to remove noise?

  • S.saravanan's picture
    May 30, 2016

    Sir, anyone tell how to play song from USB readed SD card connection with 3.5mm jack ..output two speaker...which ic I choose?.. Please describe

  • swetharani L K's picture
    swetharani L K
    Jun 09, 2016

    i like this project

  • min's picture
    Jul 04, 2016

    If I remove the battery, will the project still function or not? Because I want to replace the battery with usb port

  • kumar's picture
    Aug 06, 2016

    can i know the cost of the this project .... reply me fast i need to submit it soon pls help.....

  • Rahul's picture
    Jul 30, 2016

    Can i make this using transistor bc548 instead of Ic?

  • Rohan's picture
    Aug 11, 2016

    It's very useful. I try to made it. connection was okk bt get the output very low. how it is increase??? plz give me suggetions..

  • dea's picture
    Sep 13, 2016

    hi. were doing this for project and i'm just wondering if you could tell me whats the power range of the three capacitors. because the shop is asking for volts..

  • Abhishek's picture
    Oct 06, 2016

    They are of 63v (10uF) and 25v (220uF) ratings, but any volt rating capacitor should work here.

  • barnabas's picture
    Sep 26, 2016

    can IC LM 386 be used for making video output or any visual display circuit

  • sushil sharma 's picture
    sushil sharma
    Oct 19, 2016

    I have make this project in ccb(copper circuit board) ..this circuit works well but the sound quality is not good..In this circuit nothing is used for voice cancellation...

  • ken's picture
    Oct 31, 2016

    Can LM358 be used to amplify a music input using the 3.5mm audio jack? Instead of using the LM368 IC chip?

  • Abhishek's picture
    Dec 01, 2016

    Yes you can use LM358 but connections will be changed accordingly, check its datasheet. But LM386 is perfect for audio amplifier circuits.

  • Simran Bisht's picture
    Simran Bisht
    Feb 06, 2017

    as i am using high pass filter at the input . so i want to confirm that positive output terminal of high pass filter should be connected to pin3 of lm386 and the negative terminal should be grounded !! am i right ?? or any further connections are needed ?? plzz tell

  • Marcelo's picture
    Feb 17, 2017

    Good day sir, can i use a 3 ohm 5W speaker ? Thank You :)

  • Keerthi's picture
    Apr 26, 2018

    Frnds if anyone had done this project then plzz tell me is it working or not.

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