Inspired, by gum!
The inspiration for this project was actually two-fold. First, I needed to make a simple, portable guitar amp that would work with an electric bass guitar as well as an acoustic six-string (with a pickup), and could be played through a speaker or headphones. I knew I had all the components needed for a basic "LM386" audio amplifier, but the second part of the inspiration didn't hit me until I was looking for an enclosure for the project. I had a few empty Eclipse gum "bottles" laying around, and upon quick inspection, I realized that the opening at the top was 2¼" (60mm) - exactly the size used by many standard PCs for the internal speaker. The goal from then on was simple - make the entire 1-chip amp fit into the container underneath the speaker, with the lid threaded on over the speaker to hold it in place.

Skills and tools required:
I'm assuming for this project that the builder has some basic electronics experience such as breadboarding simple circuits, wiring and soldering. Tools needed for the electronics assembly are the usual hand tools - wire cutters, needlenose pliers, a low-wattage soldering iron and some rosin-core solder. A helping-hands vise setup would be great if you have one. Not a lot of mechanical skill needed here, just some drilling and light finishing which we'll get to in Step 5. A power drill and a few smaller bits (up to about  ¼") will be needed, and if you've never used one before, a tapered reamer is the perfect tool for getting all the jacks and switches to fit perfectly through the sides of the plastic container.

The components required are included in Step 1. You may have a few of them lying around, but even if not the whole list could be purchased for under $10.

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HornedRat3 months ago


I am new to this stuff, so sorry for my dumb question. It is quite hard in my town to get the capacitors with exact same parameters. Therefore I would like to ask you about how to replace them.
Could i use 3.3uF 16V capacitor instead of 4.7uF 16V? What difference would it make?
The same question about using 22uF 16V instead of 10uF.

I would be very thankful for an answer.

spandan966 months ago

Hey !! i made this amp and it works really well....but i want to add more components to it like Volume control, Bass, Treble, Middle, basically the tone features....so can you give me some suggestions....? :)

Sir can you design a pcb for this thank you in advance :D
The Prof1 year ago

I have just finished making three of these and none of them work. I have checked and double checked the circuits and they are correct. All I am getting is a buzzing sound out of the speaker/headphone. And then I get nothing. Is there an erratum for the circuit? I have promised to make these for some of my friends and I have been struggling for 3 days. Any help would point me in the right direction.

mdgrover (author)  The Prof1 year ago

Hello Prof - apologies for the late reply on this. Any luck yet? Did you breadboard the circuit first or did you solder it together?

I have the same problem. Did the circuit in different forms: on Bread-board, on PCB, direct wiring. Each time I used an 8-pin socket and at the end inserted the IC. Each time I get just a buzz, quite loud. This happens even before I insert the Jack in the guitar, but if the cable is however plugged in the amp. Oh! And the LED does not light-up. LED works fine on its own :)

PetarK9 months ago

Hello my question is..if i wanna bigger speaker can i just put it or i must change something?

Can I simulate this on Proteus? How? I mean... I dont know what's the equivalent J1, J2, and some other components mentioned for the Proteus part.

rurinix made it!10 months ago

Version 2 also fits in an Altoids tin. :)

GiV111 months ago

Hello, i found this post very nice but i was wondering, can you use it also for a Bass guitar? and if not what do i need to chance or can you help me with making one? I don't know alot about it but i can make things like it only not develop them.

Thank you ;D

mdgrover (author)  GiV111 months ago

Hello GIV1 - thanks for the note. This amp will actually work fine with an electric bass. My son used one of the first ones I built with his bass.

GiV1 mdgrover11 months ago

Hey, thats niceto hear. Now i'm going to start to build one for sure ;D. And how can i maybe improve the amp if i for example take a bigger speaker what do i need to change or how can i calculate or how did you find this out.

Thank you so much already ;D

GiV111 months ago

Hello, i found this post very nice but i was wondering, can you use it also for a Bass guitar? and if not what do i need to chance or can you help me with making one? I don't know alot about it but i can make things like it only not develop them.

Thank you ;D

robman6161 year ago

Hi thanks so much for the great indestructible i have built 2 of them now. However, though they both work fine the speaker always has extreame amounts of gain, there is no clear sound. Any advice?

mdgrover (author)  robman6161 year ago

Hi robman616 - sounds like you made the original version since you have a speaker. What are you using for the input (acoustic or electric guitar, mp3 player)?

Just to add a lil more info. I made this on two different pcb's and still the same thing. All connections are good and nothing is touching. I really would like to get some help with this.

mdgrover (author)  Guysmiley861 year ago

Hey Guysmiley86 - that's great that you were able to get this working fine on a breadboard. It's possible one or more parts could have been damaged from heat in the soldering process, especially the LM386 chip. Did you use a heat sink or other tool to protect the IC from heat while soldering the pins? If you're really worried about overheating the chip you can solder an 8-pin socket into your PCB and then just pop the IC into the socket afterward.

Dazzstudio1 year ago

good stuff

I am having a problem with this as well it works fine on a breadboard but when soldered together it works then doesn't. I do get some sound but it echos. Can u help with this???

kegerator1 year ago

Thank you for this, I hooked it up and sounds great (Rev 2, headphones only). However I only have sound from the left channel, is that normal.

vdo31 year ago

Any ideas on how to make a tiny little amp I can put in my pocket? I
don't need speakers just a headphone jack, I had one of those mini vox
amps that plug into your guitar but they're in the way and the jack
snaps easily if you accidentaly hit it on something since it's just a
big piece of plastic attached to the corner of your guitar.

You could discard the speaker and just install the earphone jack
đdenda1 year ago

Can you tell me what I need to change to make it into a 1W amp?

I know I need to change LM386N-1 to LM386N-4, but what about other stuff? Potentiometer for example?
Thanks in advance!

Oh yes, I also have 2 speakers rated at 3W 4 Ohm. If I wire those to in series, will I get 8 Ohms?

Bro the wattage of the circuit can only handle 1/2 watt speakers so it wont work. Hope I helped. :)
Thnx so much bro it worked so well!

I want to ask, if I can't find the op-amp LM386, can I use any other op-amp? If so, what op-amp will works? Thanks before :)

mdgrover (author)  jhardenberg1 year ago

Unfortunately replacing the LM386 with another op-amp isn't easy to do. The pinout isn't like other standard op-amps, and you would need to change other components in the circuit.

Looks like you are in Indonesia - not sure but Futurlec might be an option:


thanks for reply. yes I'm in Indonesia. and LM386 is hard to find here. it's easier to find UA741 op-amp. at first I thought it could replace the LM386. if it is hard to do, maybe I should search and buy from the internet. I'm trying to make this for my university task. so, thanks for your advice :)


Shafer30001 year ago

Awesome work. Trying to do something like this with an old lunch box.
Newb Question: Is C1 and C3 meant to act as a filter?

mdgrover (author)  Shafer30001 year ago
Hi there and thanks for trying this out! And you're right about the filters.

C1 is a high-pass (DC-blocking) filter that the LM386 requires because of the way we're using the chip's inputs here.

C3 is required to couple the output to the speaker - it actually forms another high-pass filter along with the speaker. If that capacitor is too small, the bass frequencies will be attenuated and the output will sound "tinny". Anything over 200μF has worked well for me.
Txdude1 year ago
Thanks for this Instructable! It worked out wonderfully, I made it as a gift for my guitar playing brother, he was blown away how good it sounded, not to mention the fact that I made it under his nose! Thanks again.
mdgrover (author)  Txdude1 year ago
That's great to hear - thanks for taking the time to share your success story!
un_named1 year ago
hello i am new to this stuff but could i use a 12v battery and a 4 ohm speaker?
Allfather1 year ago
Is there a way to add distortion or other effects? Im doing this for a science fair this is a great instructable
mdgrover (author)  Allfather1 year ago
Thanks for the kind words. There is some natural distortion in the circuit at higher gain levels, but if you wanted to you could add effects pedals between your guitar and the amp's input.
I know this may sound as a noob question but how would you actually ground the circuit, what would you connect the ground connections to?
mdgrover (author)  o0SLOVAKIA0o1 year ago
It's a good question actually. The ground points in the circuit all connect to each other. The negative side of the battery serves as the ground.
Allfather1 year ago
Can't find a .5 watt speaker for sp1 will .25 work?
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