Instructables
Picture of The tiny Audio Amplifier
em385_width.jpg
em386_height.jpg
A tiny, cheap Amplifier where it can be incorporated almost anywhere.
Connect your MP3,iPod,Laptop,Cell Phone... and you got your self a DIY portable stereo.
It can be powered using batteries and be helpful in many cases.
It is capable to drive a small 8 Ohm speaker or even a combination of a small in diameter
say 2-3 inch woofer and a tweeter for better acoustics.
 
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Step 1: The main ingredient

Picture of The main ingredient
The main ingredient is the LM386N IC witch is a low voltage audio power amplifier.  
Let me stay here and say that I'm not the Columbus, who discovered America!
There are plenty of information out there, just type LM386.
To begin with...
LM386.pdf264 KB

Step 2: Parts you're gonna need

Picture of Parts you're gonna need
LM386 UPPER VIEW .bmp
LM386 PCB LAYOUT.bmp
LM386 SPC.bmp
PARTS PIST – Amplifier – For stereo operation all parts (x2) except P1

A small PCB 3,5cm x 3,5cm
IC = LM386N (8 pin chip) & each case
R1 = 10 Kohm (Brown, black, orange, gold)
R2 = 10 Ohm (Brown, black, black, gold)
R3 = 620 Ohm (Blue, red, brown, gold)
P1 = 10 Kohm trimmer for PCB or logarithmic potentiometer to be screwed on a project box
          [for stereo operation ask for 1 (one) stereo logarithmic potentiometer]
C1 = 10uf/25V electrolytic capacitor (caution: +/- polarized item, follow the recommendation)  
C2 = 100uf/25V electrolytic capacitor (caution: +/- polarized item, follow the recommendation)
C3 = 220uf/25V electrolytic capacitor (caution: +/- polarized item, follow the recommendation)
C4 = .01uf/63V ceramic capacitor (non polarized)
C5 = .033uf/63V ceramic capacitor (non polarized)
C6 = .047uf63V ceramic capacitor (non polarized)
LED = 3mm red led (caution: +/- polarized item, follow the recommendation)
Connectors = 3 x double PCB connectors
POWER = 9V Battery & clip or build a 12VDC stabilized power supply to be connected to 110VAC or 220VAC mains,
depends on where you live.
tbenard3 months ago
Can anyone tell the voltage rating required for each component.
stubbsonic11 months ago
Any idea how many watts this produces?
frapedia (author)  stubbsonic7 months ago

As most manufacturers claim, the LM386 can output at 6v input / 8 Ohm load(speaker) = about 300 mW. For 9v input / 8 Ohm = about 600 mW.
You can google around for < lm386 datasheet > and see the chart: device dissipation vs output power - 4Ω - 8Ω - 16Ω load.

bsaw9 months ago
Can you give me the audio jack image for stereo operation? or you can just give the Simulation? :D
frapedia (author)  bsaw7 months ago

google around for < stereo audio jack wiring >
Depending on your needs, for audio input the most common uses are 2 x RCA connectors or a female stereo 3.5mm jack.

frapedia (author) 1 year ago
I'm afraid i have lost some files with the actual pcb dimensions. The below dimensions given are for the Ver.:1, the first 3 pictures of the instructable.
For those who wish to use the Ver.:2, the illustrated ones here is a tip. Use a paint App like corel photo-paint. At the print process shrink the illustrated pcb image to the point the LM386 ic pins fit to the printed holes of the printed pcb. This is a try and error process and i know it's not the best way, i am sorry for that.
frapedia (author) 1 year ago
I have added 2 more pictures showing the PCB dimensions.
frapedia (author) 1 year ago
I'm sorry for the delay guys but it's summer time, you know...
Anyway, PCB width = 28.5mm x PCB height = 25.5mm form border to border.
If it is to use the Amp as audio/music instrument it's best to add the low filter (R1 + C2) to the circuit as it acts like a bass boost. Now, if for any reason you do not wish to use the low filter use a wire between PIN1 and PIN5 of LM386.
C1 capacitor (MAX GAIN) boosts the volume and again if you are intent to use the Amp as music instrument it's best to add the C1. If for any reason you do not wish to add C1 simply removed.
SW (switch) added to connect/disconnect the C1 and can be removed from the PCB.
Remember to connect a wire between C3's positive pin and LM386's pin 5.
frapedia (author)  frapedia1 year ago
P1 is a potentiometer, the usual knob all amplifiers have to adjust the volume.
Stensrud1 year ago
What are the dimensions for this amplifier?
cparker11 year ago
Can you add a picture diagram that shows all the parts together on the PCB like the one for the one that doesn't have bass boost so I can see what it looks like? Thank you.
mitsof1 year ago
I have made the pcb based on your schematic.Here is the whole process. http://www.youtube.com/watch?v=-XhLMPXxDQk
mitsof1 year ago
Φίλε τί διαστάσεις πρέπει να έχει το pcb;Η εικόνα που δίνεις είναι πολύ μεγάλη.Μπορείς να βάλεις μια εικόνα του pcb στις πραγματικές του διάστασεις;
rimar20001 year ago
This seems ideal for my needs. Would you think this is a suitable electronic project for a person like me, that barely can solder a cable? I am half enthusiastic, half fearful to initiate it.
frapedia (author) 1 year ago
salexandridis,
sorry for the delay!
nice to know you like it :)
[SW GAIN] is a jumper where C1's positive (+) is being connected to the rest of the circuit. Therefore a gain of 200 is applied.
Wraio kyklwmataki re Frapedia! Sta pin SW kai GAIN ti syndeeis? Diakopth me thn mia epafh sto SW kai thn allh sto GAIN?
Eyxaristw ek twn proterwn.


And for the rest of the world who might encounter simiral problems:

"What should be connected to pins SW and GAIN? Is it a switch of which one contact is connected to SW and the other to GAIN?"
xbuntu2 years ago
Shouldm't the PCB be 10 times larger each way
frapedia (author)  xbuntu2 years ago
Yes you're absolutely right, it has to be 3,5 cm x 3.5 cm. my mistake!