LM386 Based Audio Amplifier Circuit

Simple Mic audio amplifier can amplify sound that is given from Microphone. This circuit can be used as “Small mic and loudspeaker system” for a small space like a room. This circuit can also be used in many applications like portable music players, intercoms, radio amplifiers, TV sound systems, Ultrasonic drivers etc. It can also be used as sound sensor for microcontrollers. It is inexpensive, low power operated and only need few components to work. This circuit is based on LM386 IC to amplify sound.

 

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.

Audio Amplifier LM386 Pinout

Pin description of LM386 is given below along with the functions of external components used for amplification.

 

Components

  • IC LM386
  • Condensor Mic
  • Speaker 8ohm
  • Capacitors- 220uF, 10uF (two), 0.1uF, 0.05uF
  • Resistor- 10k (two)
  • Potentiometer- 100k
  • Battery 5-12v

 

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. In our circuit it is connected to the positive terminal of the condenser mic with a 100k potentiometer RV1. Potentiometer acts as volume control knob.

A capacitor C5 of 0.1uF has also been used along with potentiometer, to remove the DC component of input signal and only allow audio (AC component) to be fed into LM386.

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. This has the same function as Capacitor C5 (0.1uF) at input side.

 

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.

LM386 Audio Amplifier Circuit Diagram

Resistor R2 (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. A suitable resistor should be used for proper working of mic, you can look up to datasheet for the value or use a variable resistor and set the proper value.

 

This LM386 audio amplifier circuit can be also used to record any sound. We just need a 3.5 mm audio plug and a computer with sound recording software. We only need to connect computer’s 3.5mm jack in place of Speaker, using 3.5mm audio plug, and we can easily record our voice or any sound into computer like a professional microphone. [Also check: Simple Audio Amplifier using IC 555]

Video: 

Comments (32)

  • Student's picture
    Student

    Why from your diagram..I count there are 3 ceramic capacitors and 3 electrolyte capacitors..? But from what you mentioned in the list, there are 5 capacitors used.. then what is the value of the other ceramic capacitor in the diagram ?? Is it you listed it wrong ?????
    Please help me !!!

    Dec 01, 2015
  • Jayant's picture
    Jayant

    Nothing is wrong, we have just used two 0.1uF ceramic capacitors in series, to get the 0.05uF (1/C = 1/C1 + 1/C2). If you have 0.05uF capacitor, you can directly use that one. Go with circuit diagram.

    Dec 05, 2015
  • Student's picture
    Student

    What type of potentiometer that you use ?

    Dec 01, 2015
  • Jayant's picture
    Jayant

    Its a normal 100k potentiometer (variable resistor).

    Dec 05, 2015
  • Saadullah Baloch's picture
    Saadullah Baloch

    condensor mic is same as buzzer in proteus ????

    Dec 04, 2015
  • Abhishek's picture
    Abhishek

    No, you should use Signal generator and generate square wave for simulate a clap sound in Proteus. It is just a representation of mic in circuit diagram, which looks like a Buzzer.

    Dec 05, 2015
  • knsubrahmanyam's picture
    knsubrahmanyam

    can I use mobile phone audio output for this circuit input...is this ckt can amplified mobile output or not....

    Dec 24, 2015
  • Maddy's picture
    Maddy

    yes, you can use mobile phone audio output.

    Jan 01, 2016
  • Ger's picture
    Ger

    Hi,
    R1 = 10 ohms ¿?

    Jan 31, 2016
  • Jayant's picture
    Jayant

    R1 is 10k, means 10 thousands ohms.

    Feb 06, 2016
  • tushar 's picture
    tushar

    should I do connections as per diagram?

    Feb 03, 2016
  • Jayant's picture
    Jayant

    Of course, you should follow circuit diagram. Project Image is also following the Circuit diagram.

    Feb 06, 2016
  • Muhammed salimpc's picture
    Muhammed salimpc

    I want to know the detail working of this circuit for my mini project. I a help of any one immediately.

    Mar 22, 2016
  • subash Soundarajan's picture
    subash Soundarajan

    What is the output current. Of your circuit from the speaker.

    Mar 29, 2016
  • Maddy's picture
    Maddy

    It would be about 350mA, check LM386 datasheet for more info.

    Apr 17, 2016
  • f's picture
    f

    Can you make it too loud

    May 07, 2016
  • Atharva's picture
    Atharva

    sir, would like to mention that u have used a 10K resistor as R2.
    if u use a 47k or 56k resistor instead of it the microphone would work more efficiently and would become more sensitive.
    and i would like to ask.
    about the capacitor C3 and C5. what value can i use if i dont have both of them???
    please help me soon..

    Jun 02, 2016
  • Maddy's picture
    Maddy

    You can use two 0.1uF capacitors in series, in place of 0.05uF capacitor. Because, in series, capacitors are added like this 1/C = 1/C1 + 1/C2 ...

    Jun 11, 2016
  • janet's picture
    janet

    In your circuit R1 is marked 10k, 10,000 ohms. This is WRONG . It is part of the Zobel network to aid stability into inductive loads (speaker/headphones) and should be a low value. As Ger said above, R1 should be 10 ohms. Check the LM386 data sheet for confirmation.

    Jul 10, 2016
  • Tharun's picture
    Tharun

    Can i use 47kohm potentiometer in place of 100k
    If no what are its effects

    Jul 19, 2016
  • SYARIF's picture
    SYARIF

    CAN I USE , SPEAKER 8 OHM 0,5 WATT?

    Sep 03, 2016
  • Abhishek's picture
    Abhishek

    Yes, in fact the speaker used is 8 ohm 0.5 watt.

    Oct 01, 2016
  • Joseph Heeren's picture
    Joseph Heeren

    Dear Sir, I would like to use the amplifier for hearing aid. In this case the loudspeaker must be replaced by a crystal earphone, what changes must I make in the circuit? Kind regards.

    Oct 03, 2016
  • Simon's picture
    Simon

    what if i want my circuit to have negative feedback and overall gain with feedback = 1000?

    Oct 13, 2016
  • Maddy's picture
    Maddy

    LM386 has gain range upto 200 only.

    Oct 27, 2016
  • emeke's picture
    emeke

    i am in nigeria so my voltage needs to be rectified to prevent my circuit from burning. What do i do?

    Nov 01, 2016
  • emeke's picture
    emeke

    i placed a signal generator instead of a mic in my proteus but it does not simulate because of excess CPU load. I have changed my resistors to pull-up and tried everything. Pls what is wrong

    Nov 02, 2016
  • Abhishek's picture
    Abhishek

    Although signal generator is generally used as replacement for Mic in proteus but there are some custom Libraries for Mic, just search them.

    Dec 01, 2016
  • Ashutosh's picture
    Ashutosh

    Do I afix a audio 3.5mm Jack instead of mic?

    Nov 20, 2016
  • Om tiwari's picture
    Om tiwari

    Is there any programming for arduino in this project

    Dec 15, 2016
  • Narayan Dhakal's picture
    Narayan Dhakal

    here u ve selected a 10 k resistor as a impedance equalizer resistor (Zobel resistor ) when i seeked through the net i found it to be 10 ohm using the online zobel resistance calculator.
    what do u wanna say?

    Jan 17, 2017

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