Simple Audio Amplifier using 555 Timer IC

Published  January 5, 2016   22
J Jayant
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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Submitted by Audu omon on Tue, 03/08/2016 - 13:20


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

Submitted by Monica on Wed, 03/09/2016 - 11:50


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

Submitted by SRIRAM on Thu, 07/14/2016 - 12:52


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?

Submitted by Just beginner on Sat, 10/01/2016 - 13:39


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.)

Submitted by Mahesh on Mon, 10/31/2016 - 21:19


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.

Submitted by Rishabh on Fri, 01/13/2017 - 19:56


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

Submitted by atul on Wed, 05/31/2017 - 14:58


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

Submitted by Adiabatics on Tue, 10/03/2017 - 11:26


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

Submitted by James on Tue, 11/07/2017 - 11:41


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