Portable audio amplifier - A perfect portable amplifier for your Mobile phone


Introduction

Everyone loves music! the louder the better. Most of the people purchase audio amps or external speakers. It will be fun to make your own audio amplifier and you will learn more about electronics.

Components


LM386 Audio opamp - 1
1K 1/4Watt resistor - 1
10 ohms 1/4Watt resistor - 1
10K potentiometer - 1
0.047uF (ceramic) capacitor - 1
250uF electrolytic capacitor - 1
10uF electrolytic capacitor - 2
8 ohm speaker - 1

Circuit Diagram

Please read modification for high bass amplifier.

The back side of the sensor PCB

The front side of sensor PCB

LM386 is a IC from Texas Instruments. It is a low voltage audio amplifier. It is very easy to make the audio amp using this chip as you need only a few external components and it works great. The gain of the amplifier is set to 20. However, it can be varied anywhere between 20 to 200 by connecting resistor and capacitor of appropriate value between the gain control pins(pin 1 and 8 of the IC).

Working

The audio input is given to pin 3 of the IC by using a 3.5mm audio pin. Pin 3 is connected to a 10K pot. which is used to adjust the volume of the system.Output is given to the speaker from pin 5 using a coupling capacitor which blocks DC.

The gain of this circuit is set to approx. 50. You can adjust the gain as per your choice. Please read the details at the end of the page to adjust the gain of the circuit.

Modification

The same circuit can be converted into a high bass amplifier for your headphones. Follow these modifications to convert it into a high bass amplifier.

1.Remove the resistor and capacitor from Pin 1 and 8.

2.Connect a 10K resistor to pin 1 and the other end of the resistor to a 0.047uF ceramic capacitor. The other end of the capacitor is connected with pin 5. Power the circuit and hear the difference.