Convert Old Speaker Into a Portable MP3 Player

I had an old speaker laying around. It was a part of a bigger home theatre unit which was broken. So, I decided to fix it and put the speaker to a good use.

In this Instructable, we will learn how to convert your old speaker into an MP3 player which plays songs from a micro SD card.

No coding required! We just have to put together some of the components available in the market.

• MP3 Player Module
• TP4056 Li-Ion Battery Charger Module
• MT3608 Power Booster Module
• Any Li-Ion battery (3.7V)
• 3W 4 ohm Speaker

Before starting with the build, let us first have a look at the heart of this project. This is an MP3 Player module which is available for cheap on the internet. It takes 5V USB or 3.7V Li-Ion Battery as a power source. This module is used for playing tracks in the MP3 format stored on a micro SD card or USB memory. For this project, we will be using a micro SD card. It has an audio jack which we won't be using. It even has an onboard 3W amplifier for connecting a 4-ohm 3W speaker. Apart from these, the module has 4 push buttons for control.

With the theory out of the way, let's get to the build part!

MP3 module board has 4 push buttons which let us play, pause and change the song. Since the board will be placed inside the speaker case, we still need to access the push buttons.

Desolder all the 4 push buttons from the board. I made a small PCB for 4 push buttons and the LED indicator. This does not need to be precise so I hand drawn the traces on a small piece of copper clad board using a permanent marker. I then etched the PCB with Ferric Chloride solution.

Now again solder the 4 push buttons and LED on our new PCB. I used fine enameled copper wire which I salvaged from an inductor to connect the new PCB to the MP3 player module. This saves a lot of space. Make sure to scrape off the insulation at the ends before soldering. Refer the wiring diagram for proper connections.

How do these switches work?

In our case, one terminal of each switch is connected together and tied to the ground while the remaining terminal from each switch is connected to the controller. Whenever a button is pressed, the input to the controller is pulled LOW i.e connected to ground and that is how it knows that the switch is pressed.

Start by removing the screws. Remove all the unwanted stuff from the inside. Desolder the speaker and keep it aside safely till we work on the case. Cut two slots on the back. One for the charging module and another for accessing the micro SD slot on the board. Your speaker case will be different. So, do the arrangements accordingly. Finally, drill two small holes on the top.

Pull the wires through the hole and fix the button PCB using hot glue as shown. In the other hole, glue one push button as shown in the picture. This push button will be used to turn ON/OFF the MP3 Player.

Set the MT3608 Power Boost module to output 5V with battery voltage as input and then wire everything together as shown in the wiring diagram.

The charger module has LED status indicators to know whether it has finished charging. I desoldered those LEDs from the board and soldered 5mm LEDs instead. I hot glued those LEDs in the back as shown.

I used a lot of hot glue and cramped everything inside the case as I did not have much space. Doesn't look great but it gets the job done. You can do it in a much better way. Just avoid short circuits!

Put everything back together and enjoy your portable MP3 Player. Thank you for sticking till the end. Hope you all love this project. Let me know if you make one for yourself. Subscribe to my YouTube channel for more upcoming projects. Thanks once again!