Introduction: Simple Stereo Amplifier 2x1W - LM386

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In this instructable I will show you how to make a 1 Watt stereo amplifier with LM386 single supply low voltage audio amplifier.

It can be powered by batteries with voltage range of 4V to 12V or by 12V wall adapter.

Step 1: Demonstration

In this video you can hear the amplifier.

Step 2: Parts List

For this instructable you will need:

1x - enclosure (KM60)

some perfboard

2x - LM386 single supply audio amplifier

1x - 7809 voltage regulator (9V)

2x - 1n4148 general purpose diode

1x - LED 5mm

1x - 1000µF electrolytic capacitor

2x - 220µF electrolytic capacitor

1x - 100µF electrolytic capacitor

3x - 100nF ceramic capacitor

1x - 10kΩ logarithmic(audio) stereo potentiometer - if you can't find logarithmic you can use linear as well

1x - 4.7kΩ resistor

1x - DC power jack

1x - 9V battery clip (6f22)

1x - 3.5mm stereo jack

1x - double pole double throw(DPDT) switch

Optional:

2x - 8pin DIP socket

1x - 6.3mm stereo jack

1x - Potentiometer knob

Step 3: Schematic and PCB

HOW IT WORKS

POWER SUPPLY

C1 and C2 are required by the regulator to ensure stability. C3 is for low frequency filtering. LED1 signalizes power. IC3 regulates the voltage to 9V. If a battery is used it is connected to BAT connector because connecting them to the regulator would waste power. BAT42 shottky diode may be used for D2 because it has lower voltage drop. I also advise to use a DPDT switch that switches batteries ON/OFF and adapter OFF/ON if not done so the amp would allways be on because of the allways connected batteries.

AMPLIFIER

The signals are fed from IN connectors to stereo potentiometers which control the voltage of the input and therefore the output volume. IC1 and IC2 amplify the signal. C5 and C7 filter high frequencies from the output. C6 and C4 protect the speakers from DC voltage which could appear by accident.(speakers don't like DC).

To make the schematic and board I used a free program CadSoft Eagle which I would recommend to anyone making schematics or PCBs.

Attachments

Step 4: Drilling the Enclosure

Unfortunately I do not have any photos of this stage but all I can say is that everything went as usual except for the speaker holes. As I did not have a proper size drill bit I chose to drill many smaller holes around the circumference and then broke the excess plastic off. After that I filed the holes so they resemble a circle.

Step 5: Wiring Diagram

Now comes the fun part of wiring all the components that will be attached to the enclosure. The images should clarify it.

Step 6: Conclusion

For me this was a fun project, especially drilling of the speaker holes. If you manage to build this project don't forget to post your results into the comments.