Instructables
Though it may not look like it, the circuit in this instructable is so easy anyone with even incredibly basic electronic skills can do this.  The circuit shown below is actually 2 mono amplifiers (mono is single channel, for those who don't know).  You don't even need to know how to solder and almost all the parts can be purchased at the nearest Radioshack. 


P.S.  The camera that I am using is old and close-up pictures are blurry.  Also the microphone on the camera sucks so the circuit will appear to be horrible-sounding, but it actually sounds good when you play it in your room or wherever.
 
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Step 1: Gather Parts

Picture of Gather Parts
What you'll need:

2-  LM386 audio amplifier IC
2-  220uf of greater capacitors
2-  0.1uf polyester capacitors
6-  jumper wires
1-  1/8" stereo headset jack
2-  speakers
1-  9 to15 volt battery
1-  connector for battery
1-  breadboard

Step 3: Build!

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Assemble.  Use the pictures as i put the notes on them:

1) Put the chips in.
2) Put in the polyester caps as shown.
3) Plug in the jumpers from pin 2 to pin 4 on each chip.
4) Attach jumpers from pin 6 to the positive side of your power supply.
5) Attach the 220uf caps as shown.
6) Connect the headset jack connections.
7) Top view of previous picture.
8) Hook up a jumper from pin 4 to the negative side of your power supply on each chip.
9)Add your battery connector observing polarity.
10) Connect your speakers.
11) Add battery and double check connections
12) Yay! You're done.

JRLSMRM2 months ago

What Class of amplifier is this? Please respond. Thank you :)

argo713 months ago

im salvaging a samsung speaker system. left and right channel has 2x8 ohms speakers and a tweeter. the center channel has 2x4 ohms in parallel. i want to know how to integrate that to an existing stereo amp from an ihome cube speaker. is there any way to make it work? i have solderless breadboard and thinking of copying the parts layout there to test fit all components.

SyrioForel3 months ago

If I wanted to add several speakers or use bigger speakers, what modifications would I have to make? Is it just as simple as adding speakers symmetrically to each amp and upping the battery power while making sure that the components can still handle the voltage?

akki52301 year ago
I want to add a volume control to this circuit. What should I do? Thanks in advance...
Kharon akki52304 months ago

If I'm correct all you need is to wire a potentiometer to the circuit. All volume controllers are potentiometers that control how much power can go through it.

hunterakagman6 months ago
what is the point of the caps? Is it to get rid of noise?
aeronut01 (author)  hunterakagman5 months ago

The capacitors filter out DC signals from the output, so in a way, yea.

asimobot6 months ago
great instructable, wat is the output in watts and can i use the small 8ohm speakers
hkerr9 months ago

what ohm are the speakers

aeronut01 (author)  hkerr9 months ago

8-ohm speakers.

hkerr aeronut019 months ago

do you know a cheap place to get them they are like £3 on ebay

blogie hkerr9 months ago

You can find some good speakers in old (and new if you want to hack a new set open) computer multimedia-ish speaker sets.

hkerr blogie9 months ago
thanks i found some old speakers in my house so im using them.
aeronut01 (author)  hkerr9 months ago

My speakers came out of an old TV that someone abandoned on the side of the road. If you have junk lying around that used to make sounds, it may have a speaker in it which you can use.

etcmn1 year ago
Thanks, this is exactly what I needed! I have a pair of small speakers that I wanted to plug into my mp3 player so I can listen to it while working. Needed something simple as my knowledge of electronics is limited.
faziefazie1 year ago
can I using potensiometer for changing the volume of the speaker? where should i put it in ?
joshr1231 year ago
hey if you have a better camera can you get me some more shots that are blury im making one and its too confusing to see (close ups/over head/ bottom)preferable.
thanks
samaddon1 year ago
hi! it's awesome and simple but may i know that if i will supply only 9volts oto the amplifier instead of 12volts will it work??
codycool552 years ago
I got them working, but the sound quality is terrible. there is tons of a static at any volume, with any speakers i try. what can i do to fix this?
aeronut01 (author)  codycool552 years ago
This happened to some of these circuits I built. On one of them, the voltage affected the quality (as the battery drained, the quality of sound got worse). On another one, the chips being too close seemed to affect each other (they didn't hum separately, but together there seemed to be bad interference with each other? Anyway, they had a lot of static). Is everything connected correctly? What are you using as a power supply? What is the value of the capacitor on the speaker output (the larger one)? Is static coming out from only one amp, or both? If all else fails, try building each amp separately, to test each one. Some one here mentioned soldering the circuit together instead of breadboarding it helps reduce static. You might want to try that as well if nothing else is working and you haven't done so already (remember to use sockets).
As far as i can tell, everything is connected correctly.

Im using a 9.6v 800 mah ni-cad battery, off of a RC car. The battery hadn't been in use for around a year, but i charged it for the amount of time i was supposed to. I tried taking 1 of the chip circuits off, and that changed nothing.

Its a 1000 10v uf cap, but i have tried using a 220v 25v cap, and the only thing that did was make he humming higher pitched.

When you say sockets, you mean like a dot and solder board? would soldering it straight together work?

I've seen other instructables where they put the bread board in a altoids tin, claiming that is to help eliminate outside interference. Would that help with my problem?

Would putting a variable resistor on the gain pins, and adjusting it around help?
codycool552 years ago
Will this work well with a 9.6v battery from an rc car? What is your battery, and where did you get it? How is the sound quality? How loud does it get?
Also how long is the battery life? what kind of speakers did you use? how can i find out the information about my speakers, as far as ohms and wattage? i recycled them out of a car, and they have almost no information printed on them.
aeronut01 (author)  codycool552 years ago
Yes, this circuit will work from a 9.6v battery. My battery is a lithium polymer, 3-cell, 11.1V, 910mAh battery. The battery, along with the smart charger (not shown here) came from here: http://www.hobby-lobby.com/   .   Have a look around, they have much better batteries than mine.  Sound quality is decent, though sometimes I would hear strange noises (usually faint) coming from the amp when it was on but nothing was playing.  Maybe soldering the circuit together instead of breadboarding it would help this, but I wouldn't know (I have long since dismantled this circuit).  The sound distorts at high  volumes, but if you push it you can get loud enough to rip your diaphragm on small speakers like mine (look at my speakers, there's a picture annotation highlighting the ripped part I glued back together).  Battery life depends on usage, speaker resistance, battery used and volume.  At medium volume, 8 ohm speakers, and moderate usage, I got at least a week out of it before recharging (my battery capacity is rather small though).  I used two 8 ohm, 2 watt speakers.  I've also tried 4 ohm speakers and they work just as well.  To find resistance, use a multimeter set to ohms (use the lowest scale), and measure the resistance.  I wouldn't know how to find the wattage, however since they are car speakers, they will definitely hold up to the 500mW each chip outputs.
Not trying to be a jerk or anything but I just had to add that the capacitors that you called "polyester capacitors" are in fact not polyester. They are mylar. :)
aeronut01 (author)  jarheadwithm162 years ago
Really? Thanks for pointing that out!
Ritesh2943 years ago
noooooooooooooooooooo i cant read it
aeronut01 (author)  Ritesh2942 years ago
Would everyone like me to post a clearer picture of the schematic?
yes please
aeronut01 (author)  NeMewSys2 years ago
Ah, the wonders of better cameras. See if the new picture is any better (the lighting was ok, not great, but the pic should be a little better now). it helps if you view it in large or original size. Remember the schematic shown is for one channel, build two of them.
jir3h4 years ago
can i ask somthing: what is the voltage of that polyester capacitor you use??
aeronut01 (author)  jir3h4 years ago
25 volts i think (not sure), but you could use 16 volt ones or higher.
From what I know, the voltage written on a capacitor is simply its operating voltage (the maximum voltage it can with stand--I THINK... I might be wrong) So, you could probably get away with using one rated for just a few volts higher than whatever the incoming voltage is.
You are right. The voltage written on the side of the cap is its maximum rating. Its always good to go a few volts higher than the input voltage. I always recommend 10% more than the input voltage.
kunchu3 years ago

Try using eagle for your schematic
TheJ0y3 years ago
Real nice tutorial m8 !

But I have a question:
I made the circuit (mono) on a breadboard to test and it has good sound so i made a PCB (stereo). When I plug the speakers (without input) one side start to make some "tic" (like ticTICTICticticticTICTIC...) the other side is fine. With input, the sound is horrible and the "tics" are still present.

I was wondering if it could be the result of the PCB layout? or because the LM386 are really close to each other? or because 1 ic is a LM386 and the other is a LM386N-1... ?

Thank you !

aeronut01 (author)  TheJ0y3 years ago
What voltage are you using, I'm not sure if it's a problem, but if it's possible, try to use the same chip for both sides. Also, do you have the volume up too loud? This particular amp distorts at high volumes. Are you sure the pcb hooks up everything correctly
Hi again !

I'm using a 15V DC power supply ( wich was working quite nice on the protoboard) I also tryed every volume settings (on iphone) aslo tryed to decrease the gain with a resistor...problem is still there :P

I looked the PCB and could not find mistakes.... should i put diodes where i split the GND? or else

P.S.: seems i have problem with the website (pictures ans posting) forgive me if my post repeats...
aeronut01 (author)  TheJ0y3 years ago
Sorry for taking so long to respond. Been off the website for a while, busy with college prep/school work. Do NOT put diodes on the gnd. Audio signal are AC and you'll most likely chop the signal in half by adding diodes. You say sound quality is terrible on one amp, not both, right? Did you solder the circuit together with sockets? It's recommended so you can swap chips out if needed. You might have a bad chip. other than that, I don't know what else could be wrong.
ok.nice.very helpful
MrLeitexxx4 years ago
i am using a 2w, 8 ohm speaker and a 0.25 watt 8 ohm speaker, with both the sound is so little , even at full ipod volume with 12 v battery that you have to put your ear really close to hear it, what could be the problem?
aeronut01 (author)  MrLeitexxx4 years ago
Are you sure that you have your signal and ground correctly hooked up? Try reversing these wires. Also, use a multimeter to check if the Battery is charged (though I'm pretty sure you already tried that). Tell me if that works
just rebuilt the circuit and it works pretty well, but i have a lot of noise, any way i cn lessen this?
aeronut01 (author)  MrLeitexxx4 years ago
What do you mean by noise?
like the bad kind, static if you catch my drift
T0C MrLeitexxx3 years ago
That's because the LM386 isn't the best sounding portable amp (you could try a bigger cap on the output like 470uF) . if you want a better sounding amp try it with a TA7368p i made one of those a few months back and the sound is perfect. it's mono like the lm386, it has a little more power consumption but more power output, i run mine on one 9v battery and it lasted about 1 month on nearly full power (about 1-2 hours a day). i used 2.5W(max 5W that's what i t said on the speakers i think they were from an old boom box) 3ohm speakers and the sound was clear and verry loud. And if you want a longer battery life just build one of the amps and make a stereo to mono converter at the imput.....for more info (if you want to buld the amp) e-mail me at t@chilyashev.com
7654321 T0C3 years ago
nah, I made a 386 amp and it sounds really clear, try a different schematic
T0C 76543213 years ago
I've tried almost all schematics (+ 4 that i made), and well, the sound isn't with the highest quality (It still sounds great but i like it when it's with GREAT sound.) And also the speaker is big part of the quality , no matter how high the quality , if the speaker sucks you'll get nothin'.
7654321 T0C3 years ago
Quite true
hey umm. i built this amplifer and checked all the connections and it didn't work. i turned on my input device, turned on a song, and tried attaching the speakers to the speakers to the 0.1uf polyester capacitor that was attached on the other end to the input

+audio in on this side_____[]_____speaker__
gnd audio in this side___________________|

i hope you can understand my diagram there. anyway it wouldn't work when it was connected so it seems that the 0.1uf polyester capacitor that i have doesn't work. what does it say on your caps?
do you think there is a problem with the rest 
i put in 3300uf cap at 16v is hat too big?
aeronut01 (author)  Electrified Geek3 years ago
The speakers are not supposed to be attached to the 0.1uF capacitors. They attach from the negative side of the electrolytic capacitor to pin 4 (or gnd, pin 4 is grounded anyway).
ixododae4 years ago
Thanks for this tut! I just soldered together one of the channels and it sounds pretty good! less joints, less interference :)
mglsotto4 years ago
what sort of speakers can be used for this particular set up? right now i have two 4ohm 3 watt speakers and a 4ohm 10 watt speaker. Will this setup work for my available speakers? If so, how do I wire all three together?
aeronut01 (author)  mglsotto4 years ago
4 ohm speakers would work, but you have to monitor the chip's temperature when you're testing it out (just touch the chip occasionally to make sure it's not burning your finger). I would recommend using only the two 3 watt speakers. If you wanted to include the 10 watt speaker as well, you would wire it in series with one of the 3 watt ones. That is, -----(speaker)--------(speaker)------. Then plug the two wires where one speaker normally goes. I'm not sure how well that would work because now you have an 8 ohm load on one channel and a 4 ohm load on the other (one channel would be louder than the other). You'll have to experiment. That's what the breadboard is for.
sc4rzz4 years ago
Very nice. I'll probably be making one of these.
What type of battery do you use?
and if my jack only has 3 wires, that would mean it's a shared gnd ?
aeronut01 (author)  sc4rzz4 years ago

My battery is a 12 volt, 3 cell, 910mAh lithium polymer battery (the battery says it puts out 11.1 volts but I measured 12).  The 910mAh only refers to its charging capacity, the battery can actually put out 14.5 amps continuously.  As for your jack, you're probably right about it being a shared gnd.  You can check by cutting open ONLY the insulation at the point where your jack cable splits in two (one for each headphone speaker).  If you see one cable split in two, it's a shared gnd.

hey i am new to electronics and i think i hooked everything up right but my 2.3 W speaker is really soft and you cant hear it unless u get really close to it. whats wrong?
aeronut01 (author)  what in the world4 years ago
Hmm,  did you try turning up the volume on the audio source (ipod, laptop, etc.)?  If that doesn't work, what kind of battery are you using (it is recommended to use 9 to 12V) ?  Finally, are you sure you didn't mix up the signal and ground wires on the audio jack?
emtiaz4 years ago
helo bro, nice work. u explain it too easily......... thannxssss & carry on :)
blindrulz4 years ago
hey nice explanation of picz
good keep it up
like u amp very much
<blind>............
 i built one but for the compacitors i used 1000uf and it seems to power my 50wat speakers with no prob..:) and i suggest putting the circuitry in a aluminum casing because i use wireless keyboard and as i type i can hear it through the speakers..lmao
Ha, I have the same iPod! Did you buy a new battery and "upgrade" the HDD with a compact flash drive?
aeronut01 (author)  TheWelfareWarrior4 years ago
Actually, no.  it's all original !!!!   Being 8 or more years old however, with the original battery, this does mean I get no more than an hour (usually less) of run time.  (You can still buy a new battery for this thing?!?!)
Yes, but they are chineese from ebay and i do not trust them... you could buy a 'new' cell phone battery and mod it in. if the battery was as big as the back of the ipod and half as thick you could get like 20 hours out of it....

and with a compact flash HDD that would improve it even more...

Dunno what or how to look up all that stuff but if you just kind of fire into google some of the stuff i'm talking about I'm sure you can research it and bring new life to a dying iPod
Does the voltage matter on the capacitors?

Also what sort of run time do you get with your battery? / What is your mAh of your battery?
aeronut01 (author)  speeddemon20084 years ago
To answer your questions, the capacitors i used are 16 volt for the electrolytics and i don't know the voltage for the polyester ones, though i think they could be 16 volts as well.  I run my circuit off a 12 volt, 910mAh battery.  However the battery is capable of providing 14.5 amps continuous and up to a 22 amp burst.  Since this circuit doesn't consume too much energy and can be run off a 9v battery, the extra energy the battery can provide gives me RIDICULOUSLY long battery life (60+ songs without recharge, sometimes more!).    jman 31, while i don't criticize your knowledge, the 16v capacitors at 12v seems to work for me.
Caps should be minimum of 25 volts if you use a 15v supply. If you run it with a 9v battery, you would be safe with 16v caps.

Can't say personally about run time, but I make guitar headphone amps out of a 386 chip that last for months of semi regular use.
Berserk874 years ago
Nice tutorial and lots of pictures, only suggestion is get clearer pictures and a readable schematic.