# 2 Watt LM380 Chip Amp

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Hey everyone.

So here's how this project came about.  I needed  two, 2 watt amps for a speaker project, and didn't want to go buy amplifyed computer speakers and rip the amp out like i see some people doing, so i decided to buid one.  Well i googled a little, and came up with a circuit for the LM380 IC.  It seemed to be a pretty popular circuit, posted on a lot of different websites, so i figured i would have a lot of support information if something went bad. well i guess i fail at google but thankfully a helpful user helped me out. c181155 helped me out, and posted a link to the datasheet which helps alot*stupid me didn't even bother to look at the datasheet...* heres the link
http://www.national.com/mpf/LM/LM380.html#Documents
So in this instructable I will walk you through the building of this amp and the things that i found confusing.

*Alot of the actual instructions are within the pictures, as i found it easier to explain this way.

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## Step 1: Materials/Tools

Materials
------------
Paper and glue
some copper strands for jumper wire

an LM380 IC
2- 25V(or higher) 470uf electrolitic capacitors
a 2.2 ohm resistor
a 10k audio taper potentiometer
a headhone jack/rca jacks/you get the point
a power supply(10-22V)

Tools
--------
soldering iron
probably some pliers
a multimeter if you have one, however you can definately make this with out one
a needle (sewing, not epidermic...)
some aligator clips will probably be very helpful, i know they were for me

## Step 2: Circuit

Here is the circuit i found so popular on google.

The second picture is the pinout for the IC.

The Third picture is how i drew the amp up, it was alot simpler for me to follow this way.

This is an incredibly simple circuit, but If you suck at building circuits like me, a couple things will throw you off.

Some problems i had: Firstly, I did not realize that pin 6 is the negative input from your ipod, and is not just grounded to -V like the others, make sure you see that.

Also, just in case you are brand new to building circuits, R2 is a 10k potentiometers, I had troubles with this, until i realized that the "ground" for the potentiometer is supposed to be the -input, not the ground from your power supply. *facepalm*

I put pins 3,4,5,7,10,11, and 12 in parallel with ground, although im pretty sure it doesnt matter(please correct me if I'm wrong!) this way works great. (by the way, these are your heatsink pins)

*Note: pins 1, 9, and 13 are not used.

## Step 3: Making the Board

Ok so im out of perfboard, and i plan on keeping this for a while so i decided to build a makeshift board...

So what i did was i glued 5 pieces of small paper together. i think you could probablly use that dense cardboard from cereal boxes, but I've never tried it.

And in order to put the components on the board, we're going to be using a needle/something sharp to put little holes in the board, then we will connect them with the jumpers.

We are going to use both sides of this board, the bottom for all grounds and output, and the top for everything else.

## Step 4: Building the Top of the Board

We will be laying this circuit out just like the circuit i drew up(step 2 picture 3).

If you run into any problems, let me know in the comments, and ill clear up whatever you dont get in this instructable.

In these pictures, i am not using a potentiometer. The reason is that i am using 2 amps for a speaker project, and will be using the potentiometer to control both.  Sorry it is not pictured, but if you follow the circuit diagram, and make sure to connect the ground of the potentiometer to you negative input and not your negative voltage, it will all work fine.

When connecting the jumpers to pins on the chip, I expanded the hole for that pin a little, pushed the jumper through and soldered the jumper to the pin on the bottom. If you are soldering directly to the chip and not using an IC socket, be careful about how long you keep your soldering iron on the chip's pins, and use a small heat sink(an aligator clip will work if you can solder fast) inbetween your iron and the chip.

If you find that your jumpers are long and dangly, just punch a few extra holes, and thread the wire through, it will tighten it up and keep everything in place.

## Step 5: Wiring the Bottom(grounds)

This part is pretty simple, just solder the negative voltage wire to all the other pins that should be connected to ground.

There isn't much to explain here, just look at the pretty pictures:)

## Step 6: Finishing Up/Testing

So thats pretty much it. Your amp should be built and hopefully be sounding great.

It's not a super high quality amp, and you could guess by the part count, but it gets the job done nicely and is super cheap to build.  Plus it took me all of 15 minutes to make the second amp, including taking these pictures.  Very simple.

Thanks for reading and have a nice day.

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## 23 Discussions

Hey! Great tutorial... If i were to use a 3.7v bat could i use lower value components or do you reckon it won't get enough power?

Actually the problem with LM380 is that being a class D amplifier it has a good amount of noise and the next thing it is not that much efficient

Can i use 9v? i want to make some portable speaker for my bike, i wanted to built it with lm386 but its only 1.5 w, and this one is 2w

6 replies

Yes! although it will be less powerful. The datasheet states that 10V is the minimum, however i just tried a 9V battery, and it plays fine. If i were you though, i would put 2 9V's in series, just because id rather my music be louder:D

thanks, i as i said i wanted to build some speaker system so where ever i go i could listen to loud music, lm386 is almost same price like lm380, but it have more parts, less power,.....thanks, i will try out this one, first with 9v, but then i will use 2 9v or 9v and 2x1.5v,.....i will post test in next month

unless you are driving some pretty efficient speakers, 2-3W wont be all that loud, just a warning. Also, you can get free samples at the TI website:) there is an Instructable somewhere for that

This is an amazing instructable,thanks for posting it !
Ive been looking around a lot for a good amplifier (IE: Not lfm386-n) however, if you search amplifier, you only get those with lm38g-n(or rather all others are swamped out).
Also, great idea with the paper/glue! (though since i am a beginner mostly, i will still buy the board.

3 replies

sorry, i didn't get a notification that i got a comment, and just saw that i didn't reply to one today... The quality is good enough for me, theres a lot of chips that will do a ton better though. There is more hum and its a lot more sensitive to things like a light being plugged into the same outlet than other amps I've build are

thank you! I too was frustrated with the surplus of lm386 amps(no saying they are bad instructables, just hard to find other amps)

thank you, hope everything goes well!

One warning: Paper is a lot more combustible than FR-4 fiberboard used in a regular circuit board. The three middle pins on each side of this circuit are "heat sink ground" -- they are supposed to be routed to a large area of copper on the circuit board, to dissipate heat.

If you play this circuit at its full power, those pins will become very hot. If you're lucky, the circuit will go into thermal overload protection. If not, your improvised "circuit board" will scorch and maybe even catch fire!