Simple Audio Amplifier using 555 Timer IC


ByJayant 22

Simple Audio Amplifier Circuit using IC 555

555 time IC is very powerful and versatile IC, it can be used in many forms. In this tutorial we are going to see how a 555 IC can be used as Audio Amplifier. A low power audio signal can be amplified using 555 Timer IC.


This circuit is divided into two parts: part one is Preamplifier circuit, which consist a BC547 transistor, a Condenser Mic and some resistors & capacitors. Second part consist a 8ohm speaker and a 555 timer IC, which is oscillating in Astable multivibrator mode, with approx. 66KHz frequency.


Required Components

555 Timer IC

Condenser Mic

8 Ohm Speaker

BC547 Transistor

Resistors - 470 Ohm, 1k, 10k, 47k, 100k, 680k ohm

Capacitors - 10µF, 1nF, 100nF

Battery - 9v

Breadboard and connecting wires


Circuit Diagram and Explanation

Simple Audio Amplifier Circuit Diagram

The audio amplifier circuit is shown in above diagram. Control PIN 5 of 555, has been used here which is generally kept grounded through .01uf capacitor. Control PIN 5 is the point of 2/3Vcc inside the 555 timer IC, so we can change this 2/3Vcc voltage through this PIN. And changing the voltage at this PIN change the width of output pulse, irrespective of value of RC components in 555 timer circuit. It follows the same principal of Pulse Width Modulation (PWM) to modulate the output wave.  We have used this functionality of Control PIN in this circuit.


Speaker does not respond to high frequency, so when there is no voltage at control PIN 5, speaker doesn’t produce any sound. When we create some sound near Condenser Mic, that sound is converted into electric signal by the Transistor, and this electric signal is fed to the control PIN 5 of 555 IC. The output pulse at PIN 3 modulate due to this voltage at control PIN, and speaker detects this DC component of Output pulse and produce sound. Basically when there is voltage at PIN 5, width of the output PULSE increases for a moment and that is detected by Speaker.


Resistor R1 is used for biasing of condenser Mic and R2 and R3 is used to provide proper biasing to transistor. We can test this circuit by blowing some air from mouth towards the Mic, the speaker will generate sound accordingly, as I have done in the Video.


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  • bheekam sharma's picture
    bheekam sharma
    Feb 05, 2016

    this is a good project

  • Noah's picture
    Feb 09, 2016

    Nice work, what do i need to produce a 5watts audio amplifier.

  • juraij's picture
    Feb 27, 2016

    Capacitors 1nf & 100nf not avialable.
    What we can do???!!!

  • Lucky's picture
    May 14, 2016

    I also had the same problem, i did know what to do. But i hope Google can give us clarity!

  • Audu omon's picture
    Audu omon
    Mar 08, 2016

    How can i convert sound ic when the original one is burnt what are the things needed for the covertion

  • Monica's picture
    Mar 09, 2016

    How would I change this circuit if I wished to implement it with a 3.5mm audio jack instead of the condenser mic?

  • lohithraj's picture
    Aug 01, 2018

    Just remove the mic and connect right and left wires together for audio in wire and gnd to another wire thats it

  • Aaron's picture
    May 09, 2016

    How good is the sound quality of this circuit?

  • Aparna's picture
    May 12, 2016

    What will happen if the Speakers have more that 8ohms???

  • SRIRAM's picture
    Jul 14, 2016

    Is it possible to use 8ohms 5 inch speaker ( more watts) in the above circuit? If not means what modification I have to do in above circuit to use bigger speaker?
    And I want to use this circuit for long distance. Example, person-1 should hear clearly person-2 talking. Distance between two persons is 20-30 meters. What changes I have to for that?

  • Shivali singh's picture
    Shivali singh
    Aug 03, 2016


  • Senri's picture
    Aug 12, 2016

    does it amplify my voice when I speak near the mic ?

  • muneeb's picture
    Sep 02, 2016

    good project

  • Just beginner's picture
    Just beginner
    Oct 01, 2016

    Do you know DC part has been stopped by C4 capacitor above speaker.its AC that's going into speaker.
    --from beginner voice.(correct me if I am wrong.)

  • Mahesh's picture
    Oct 31, 2016

    Guys,when I connected the circuit as given in the diagram a beeep... sound is being heard,though the input is being amplified. Can you tell me why this is happening????????How to stop this unwanted beep sound.

  • Rishabh's picture
    Jan 13, 2017

    Pin 7 is not connected so how does the capacitor discharge? I did not understand anyone, please.

  • atul's picture
    May 31, 2017

    my circuit is not work [ic 555 audio] plz help.

  • Adiabatics 's picture
    Oct 03, 2017

    Please I was unable to get R2=680k resistor. Is there any alternative

  • James's picture
    Nov 07, 2017

    Can you put a headphone jack instead of a mic without changing anything else, i would think you could but please someone let us know if it would be that easy or if you would have to change alot

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