Coke Can Phone Speaker




Intro: Coke Can Phone Speaker

This instructable is a guide on how to build an amazingly small, powerful phone speaker inside a coke can. Total cost of this speaker is below 20$, excluding batteries and coke can of course. Advantages of this speaker include:

  1. Loudness
  2. Stereo Sound (vs. Mono found on cheap phones, etc.)
  3. Very Energy Efficient
  4. Cool looking
  5. Recycled
  6. Very cheap compared to buying a speaker
  7. You can add your own features
  8. Long Battery Life

Step 1: Gathering Your Parts

For this project you will need the following parts:

  • 2 x LM386 - This is our main audio amplifier IC. It is available basically everywhere and is very cheap. I paid around 40 cents for 10 of them, but that is china prices. In the US they go for around 1$ per ten of them.
  • 4 x 200uF caps - These are the main filtering caps. You could go for expensive Japanese audio ones, but I found that the Chinese 'Chenbin' brand ones are good enough. Any cheap cap should do, as this is not some sort of crazy high end system.
  • 2 x 100uF caps - These caps are used for setting the gain. Again 'Chenbin' brand it is.
  • 2 x 1W 8R 50mm - speakers. They are super cheap, around 30 cents for 1. And they sound decent. For better audio quality, definitely get some better speakers.
  • 10 Ohm Resistor - Just buy 100 of them, they are cheap and always useful to have.
  • 2 x 10K potentiometer
  • 1K Ohm Resistor - Again, just buy 100. You will use them in other projects.
  • 1 x Audio Cable - To connect your phone
  • 2 x 9V Battery Clip
  • 1 x Breadboard - If you want to prototype your circuit.
  • 1 x Coke Can

Step 2: Gathering Your Tools

This is a fairly advanced project, so you require at least a minimum selection of tools. These include:

  • A Dremel Rotary Tool. Preferably the Dremel 3000. We need this to cut the protoboard and the coke cans. Similar rotary tools from other brands might also work, but I can only recommend the Dremel 3000. (If I am referring to 'The Dremel', I mean the rotary tool.
  • A 3.2 mm drill bit for the dremel. (It should come with one)
  • Temperature controlled Soldering Iron. You can get a decent one for as little as 80$ if you don't have one already. I use the Hakko FX-888 and it is doing a great job.
  • A reinforced grinding piece for the dremel. (again, should be included in the set, otherwise the speedclick ones are great)
  • A hot glue gun. Mine is from Dremel, The Dremel 940, but any hot glue gun should do. Just don't buy the ultra cheap ones, as they can melt in your hand.
  • Wire snips.
  • Wire Strippers.
  • Craft Knife, Scissors
  • Needle Nose Pliers
  • Breathing Mask - To prevent you from breathing the dust while grinding.
  • Goggles - To protect you eyes from dust while grinding.

Step 3: The Basic Framework

Now we finally reach the building phase, after two rather long (and boring) parts and tools lists. So for step 3, it is to start cutting up the coke can.

Use the Dremel to cut the top and the bottom from the coke can. Only cut out the inside, so that the speakers fit perfectly. Also drill a hole to fit the aux input. Use a drill bit of the same size as the plug on your cable.

    After this, move on to the next step.

    Step 4: Assembling the Amplifier

    Now we are getting to the interesting bit. Cut a 4cm x 4cm piece of Protoboard. This will be where your amplifier will be installed upon. Look at the pictures and schematic of the circuit. Use it to guide yourself in the installation process.

    After finishing the two amps, use a small piece of protoboard and some wires to split the audio signal for the two speakers. Then build use protoboard, wires, battery clips and hot glue to construct the battery holder.

    After this we can move on to the next fun step. Installing it in the coke can.

    Step 5: Installation

    Put a 9V battery inside the clip. Now start by putting the end of your aux cable through the hole in the can. (see pic. 1)

    Put the rest of the installation inside. Starting with an amplifier, followed by the 9v battery, followed by the aux splitter and lastly the second amplifier. Ensure that the speaker wires that are attached to the amplifier are coming out of both sides of the can.

    Solder on the speakers onto the cables. Be careful of the speakers polarity.

    For the last touch, use some hot glue to fix both speakers in place.

    Step 6: Enjoy

    You have now build a amazing speaker. Enjoy it.

    Some potential improvements for the project would probably some more expensive speakers, EMF protection and maybe a Bluetooth module. Also, a rechargeable battery might be nice.

    If you enjoyed this instructable and think it is pretty darn cool, I would be happy if you could vote for this instructable in the seeedstudio rephone contest.



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    23 Discussions


    3 years ago

    Just a thought but you can actually cut the top out cleanly with a hand can opener. I've done it several times. That way you don't risk damaging the can.

    2 replies

    Reply 2 years ago on Introduction

    And if you use a similarly sized soup or vegetable can, you can of course cut out BOTH the top and bottom with a can opener. But then it would no longer be a Coke can speaker...


    Good Idea. Might be worth considering, especially since most people do not have a Dremel readily at home. I just chose the Dremel as it was the best tool I had at hand. I wasn't really worried about damaging the can, as I had enough to repeat the process and get it right.


    1 year ago

    i just connect my one of old speaker from 5.1 system to aux cable.

    the problem is that it is not loud.

    how can i increase volune ?

    Juan FelipeR

    2 years ago

    Hey man, great project, just a quick question, when i connect my phone and hit play a lot of static comes out of the speakers, the sound is not clean at all, do you knw why this might be?

    2 replies
    jsincnJuan FelipeR

    Reply 2 years ago

    Hi, are you trying it on a breadboard or on a protoboard, also is the issue on both amps or just on one? From my experience on breadboards it can always cause issues. If you soldered it on protoboard, I would recommend checking your soldering connections. If it is just on one of the amps, sometimes rebuilding the affected amp will help. I also had a few failed ones while prototyping. If it all doesn't help, please post some pics of your circuit so that I can take a look at them. jsincn

    Juan FelipeRjsincn

    Reply 2 years ago

    Hi, yes im actually prototyping on a breadboard so that might be the issue, I'm gonna try soldering. Thanks

    Carlos EduardoG1

    2 years ago

    Hi, I`m gathering the parts to assembly this cool project. I just need to know the voltage of the caps. 10v? 16v? 25v?


    1 reply
    jsincnCarlos EduardoG1

    Reply 2 years ago

    Hi, I used 35V caps, but I think 25V or even 16V should also work. I just went for the cheapest chenbin brand ones.


    3 years ago on Introduction

    my friend! its a good project and i love to make it! but i dont know the pins of lm386

    please denote the pins in the picture.

    thanks a lot!

    2 replies

    Reply 3 years ago

    Hi, I will at that. Until then I would recommend looking at the Data sheet for the LM386. Just google it. :)

    Use a craft knife and carefully remove the speaker. Pull out the structure and replace the two batteries. You should only have to do that around once every month, which is the estimated standby time for the speaker. (Around 10 hours while listening to music). But, as I said above, it would have been better to get a rechargeable battery and build a charging circuit. However, I did not have a suitably sized rechargeable battery at hand.


    Reply 3 years ago on Introduction

    You could also wire in a dc jack along with the battery snap and use a 9v dc adapter.


    3 years ago on Introduction

    This is great. I just have a few questions.

    What sizes are the pots? They aren't shown on the parts list or labeled on schematic. Also, the parts list seems to be missing two 100 ohm resistors.

    1 reply

    Reply 3 years ago

    Hi, thanks. I forgot to add them. They are 10K pods. Also, which 100 ohm resistors are you talking about?