Introduction: Simple Stereo Amplifier 2x1W - LM386

Picture of Simple Stereo Amplifier 2x1W - LM386

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

Picture of 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.

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

Picture of 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

Picture of 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.

Comments

ManishJ27 (author)2017-06-16

I make both sets of this should I connect power and audio in parallel to each set

mihaelplibersek18 (author)2017-03-30

can I use 4ohm speakers instead of 8ohm?

It should work.

Brosiman (author)2016-10-30

Nice project,although i would like to see a clearer schematic.

DIY Circuits (author)Brosiman2016-11-04

Click on the image then right click and select show picture. Then you should be also able to zoom.
Or did you mean something else ?

Brosiman (author)DIY Circuits2016-11-04

I meant something else ,the way the LM 386 is shown in the circuit: not as a triangle but a rectangle,I find it easier to follow it that way....

DIY Circuits (author)Brosiman2016-11-06

oh I'm sorry, that's just the way it looks in eagle.

PansiluJ (author)2016-11-03

hey.

can i use 12v power supply for this? ithink it must be possible becouse 7809 will regulate the volthage to 9v.

DIY Circuits (author)PansiluJ2016-11-04

Yes, that is what 7809 is supposed to do.

irishjim68 made it! (author)2016-10-22

Very nice build. I love those little LM386 chip amps. I made a very similar unit a few years ago. I used a switching power jack which will disconnect the 9v batteries when it is inserted. The two 9v are wired in parallel to give longer run time. I designed this to be used with MP3 player or smartphone so I did not add a potentiometer volume control to the circuit.

DIY Circuits (author)irishjim682016-11-01

Thank you so much, I didn't know that my dc jack has that switching feature! Neverthless it would not help me because then the batteries would be connected to voltage regulator(linear) and I don't want to waste any of their power. So I connected them through diode to the output of the regulator.

cbaetsen (author)2016-10-31

Radio Shack used to sell aa LM386 stereo preamp much like what you built. I used one in my arcade cabinet and another to amplify the output of my crystal radios.

DIY Hacks and How Tos (author)2016-10-22

Nice amp project. You should enter it in the Amps and Speakers contest that is cuurently running

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