Introduction: DIY Bluetooth Speaker in a Soda Can

About: Hello - I am the scientist formerly known as Naegeli and of course I was inspired by the artist formerly known as Prince. But in contrast to his royal badness I do not want be become the king of pop but the ki…

You want to listen to music when you're on the go? This Instructable shows you how to make yourself a portable Bluetooth speaker that is easy to hook up to your smartphone or another compatible device to listen to your favorite songs. The system is integrated into a soda can. The print on the outside of the soda can has been removed (see Link) so that the aluminum housing gives this portable speaker a stylish finish.

The unique feature is a plastic PET bottle glued on the inside of the soda can so the can has certain stiffness and can be taken apart easily. The system is powered by one rechargeable battery. The components are cheap and easily available.

Step 1: Parts List

For this project you need the following items:

  • Soda cans (for ink removal see Link)
  • PET plastic bottle
  • Bluetooth Micro Audio Amplifier Module
  • Mini Audio Speakers
  • Charger Module
  • Battery
  • Battery Case Holder
  • Switch
  • Micro USB Cable
  • Two component adhesive
  • Hot glue gun
  • Shrink tubing
  • Insulating Tape
  • Dremel tool

More detail about the components can be found in the description of the video.

Step 2: Preparation of the Soda Can

The basic part of the Bluetooth speakers is made from two soda cans. One acts as the bottom part the second one is used as a lid. But how do they fit together?

The trick is to glue a PET plastic bottle into a the soda can, with the edge of the PET plastic bottle overlapping the soda can. The other part of the soda can is then pushed over the protruding PET plastic bottle. The plastic bottle therefore should be little bit smaller so that the can fits just right. Maybe it takes some time until you have found the right combination.

In my part of the world three main soda can types are sold with the following diameters:

  • 66 mm
  • 58 mm
  • 53 mm

For this project I used the large one (66 mm diameter). Clean the emptied soda cans by rinsing twice with water and then let it dry. Before you start to cut the soda cans apart, you should consider if you want to remove the ink from the soda can surface. I have already posted an Instructable how to remove the ink from soda cans. You can find it under the following link: How to remove ink from soda cans.

Now we start a procedure to carefully cut off the upper and lower parts of the can. Pay attention to your fingers during this procedure, as aluminum edges can lead to heavy cuts. Use the utility knife to mark a groove around the can. Hold the knife on a piece of wood at a level plane and then rotate the can around. It is not necessary to cut through the aluminum. Apply some pressure with your fingernail near the groove to separate the top and the bottom part (see video: DIY phone case from soda cans). You can also use scissors to cut along the groove. Repeat this step for both soda cans.

Step 3: Prepare Opening for Loudspeaker, ON/OFF Switch and Charger Module

Make a cardboard template to mark the center on both sides of the soda can. Use a circle cutter to make a groove around the center point in the size of the speaker. Use scissors to enlarge the center point. Start from the hole in the center to remove the marked circle with pliers.

With a Dremel tool make eight additional holes around the opening for the loudspeaker. This holes are required for the Bluetooth signal.

In order that the device can be turned ON and OFF a hole has to be made into the soda can for the switch and another hole for the charging module. As the aluminum is a good conductor, isolate both sides of the can near the opening for the charging module with insulating tape.

Step 4: Prepare PET Bottle and Combine With Soda Can

To be able to fix the two soda cans together, a PET plastic bottle is integrated into one of the two soda cans.

The PET plastic bottle is cut to length with a knife in such a way that you have a kind of plastic tube in the end. Then coat the inside of the soda can well with two-component adhesive. The PET tube is then pressed into the can with the edge of the PET plastic bottle overlapping the soda can for about two centimeters.

After the adhesive has cured, two semicircles are cut out of the overlapping PET bottle to join the two soda cans together.

Step 5: Electronics

The electrical circuit is so simple that I did not add a circuit diagram. Just orientate yourself by the picture. The Bluetooth module comes with cables for the speakers and for the battery. Solder the cables to the two speakers and then you can connect the speakers to the board.
The power supply is a bit more complex. First you have to solder the charging module to the battery. This charger module switches off the power when the battery is low, and on the other hand the module prevents the battery from overcharging when power is applied. Integrate the ON/OFF switch between the charger module and the Bluetooth module.

Then pack the charger module in heat shrink tubing and heat it so that the charger module is well insulated. Then insert the micro USB plug at the end of the charger module through the hole you made in the soda can and connect the USB cable from the outside. Position the charger module along the inside wall of the soda can and then pour hot glue over the entire module to permanently fix it.

The switch is integrated in the same way. First isolate the contacts and after installing you cover it with hot glue.

Step 6: Close the Soda Can

Finally put the Bluetooth module into a small plastic bag as insulation. Then pack the battery into the battery box. Arrange everything within the soda can and then connect the soda can half's. Fix the two half's with insulation tape. Then start Bluetooth on your smart phone and connect with the Bluetooth module. Choose you favorite song and voilà.....