Introduction: World's Smallest Bluetooth Speaker From Old Parts

About: I love to tinker and make things from other things. I post videos on my Youtube channel that showcase some of the silly homemade inventions and gadgets that I mess with. I'm also the guy with the most viewed …

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In this Instructable you will learn how to make an ultra tiny homemade bluetooth speaker that packs quite the punch for it's small size. Ideally, I would love for you to do the same as I did and recycle/upcycle old parts from past projects. If not, all of the parts and supplies can be purchased in most countries. You don't have to get the EXACT same sized parts as I used. It's okay if your speaker or battery is a little bit bigger/smaller.



  1. CJMCU PAM8302 (Mono Class D Amplifier Board).
  2. Speaker from Old Phone.
  3. Bluetooth Board from old bluetooth hands-free earpiece (The smaller the better!).
  4. Small 1S 3.7v LIPO battery cell 50mah.

Tools and Other Stuff

  1. Soldering Iron and Solder. (Every maker and tinkerer should have one - If not, you could improvise).
  2. Double Sided Adhesive Tape or Poster Putty.
  3. Wire trimmer or a good set of teeth.
  4. You will also need a device to connect to the speaker via bluetooth. A smartphone is a good option for this.
  5. A playlist of your favorite music.
  6. Coffee - Just because, coffee!

Step 1: Watch the Video!

Watching a video seems to be the way the cool people learn things on the internet but, if you're old-school, you can enjoy reading the written instructions that follow!If you can't see the video above, find it on my channel here -

Step 2:

If you've chosen to follow the written version, you are awesome!

Let's begin by taking apart the mobile phone and removing it's speaker/ringer. Smartphones will usually have ribbon cables attached to the speaker so, I do not recommend you use those unless you are completely comfortable working with ribbon cables. I was fortunate enough to have this old school mobile phone laying in my junk box. I later found out that it had a basic speaker that I thought would be loud enough for this project. So Perfect.

You may now take a sip of coffee before the next step.

Step 3: The CJMCU PAM8302 (Mono Class D Amplifier)

This is the CJMCU PAM8302 (Mono Class D Amplifier). It's an amazingly small amplifier board that's going to allow us to use the speaker we pulled out from the mobile phone. We will need to amplify the signal in order to get a pleasing (obnoxiously loud) volume.

The PCB is labelled nicely and the connections from here on out should seem pretty intuitive, but here is an explanation of what the labels mean and what gets connected to it.

  • Load - This is where you connect your speaker. Negative to - and positive to +
  • Audio in (+/-) - This is where you connect the source of your audio. In this case, this is where you will connect the negative and positive wires from the bluetooth speaker out.
  • Shutdown - Optional. You can add a switch between this pin and the ground pin to mute the audio output.
  • 2-5v DC - This is where you will connect the positive end of a battery
  • Ground - This is where you will connect the negative end of a battery

Another sip of coffee is required for the next step.

Step 4: The Bluetooth Transmitter

This is what the inside of a bluetooth earpiece should look like. Every PCB will be labelled differently but the basic connections are as follows.

  • Battery in (negative and positive)
  • Speaker out (negative and positive)
  • Microphone out (negative and positive)

Connect the LIPO battery to the battery in pins on your bluetooth transmitter if yours does not already have one connected. Cut off any speaker that may still be attached and move to the next step.

Step 5: Connect Everything!

Here is a simple wiring diagram that you can follow and connect all of the parts together. I also added 2 photos of what my connections looked like.

Solder all of the wires as shown and then move on to the next step after taking another sip of coffee.

Step 6: Neaten Up the Wiring

As you saw in the previous step, the wiring looked nasty!

Tidy it up by sticking everything together neatly with a couple pieces of double side tape or poster putty. Once you're done, it should look like this.

Step 7: Test!

It's time to test!

Press the little button on your bluetooth transmitter and pair it with your smartphone.

Once paired you can play your favorite songs!

Remember that you can charge the speaker as you would have charged the earpiece. Simple!

One more step!

Step 8: Demo

As much as you may have enjoyed reading through these instructions, there is no technology in existence that can allow you toread sound. It's time to watch the video and hear how this little speaker really sounds!

If you can't see the video above, find it on my channel here -

If you liked this project, consider voting for it to win the Trash to Treasure contest here -

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