Introduction: How to Make a Portable Speaker From Old Recycled Parts+ Bluetooth Feature on Any Speaker


In this Instructables I will build a Portable Speaker out of Recycled or Reused parts. The main idea was to make a portable Bluetooth speaker for Cheap so the reused parts was the way to go. Since i had all the parts lying around. it costed me only 150 INR to build this. But it wouldn't cost much if you find the parts from scrap pile.

I will use the batteries from old mobile phone. The amplifier unit is from old Car Stereo System. The Casing is made from packaging wrapper roll and some parts found in my garage.

So in this instructables I will show you how you can easily build a portable speaker and some basic concepts to know for building a portable speaker system.

As a Bonus I will show you how you can add Bluetooth Feature to any speaker to enjoy wireless music.

Watch this video of making of portable speaker:

Step 1: Materials Used

  1. Lithium Batteries from old mobile phone
  2. 8 ohm Speaker
  3. Amplifier Board ( TDA 7297 15W) or any amplifier board
  4. 100 kohm Potentio-meter
  5. 1 kohm resistor
  6. LED
  7. Switch
  8. DC Jack
  9. 3.5 mm Audio Input Jack
  10. 3.5mm AUX Cable
  11. Some Wires
  12. Soldering Equipment ( Iron, Flux, Solder wire,etc)
  13. Some Basic Tools
  14. Spray paint or Oil Paint
  15. Speaker Mesh
  16. 12v adapter for Charging Battery pack

Step 2: Audio Input and Volume Control

I start by making the Audio Input section of this build. A 3.5 mm audio jack is used as the input port. As I am using only one speaker, I am connecting Right and Left channel together. So the Audio signal is fed to any one channel and to ground.

The Volume is controlled using 100 kohm pot. There are three terminals in pot. Middle terminal is "Signal OUT". Pin 1 is "Signal IN" and pin 3 is "Ground". Signal OUT and Ground is then connected to Audio IN of amplifier Board. ( I will explain about amplifiers in coming steps).

Note: Do not Connect Right and Left Channel if you are planning to use Two Speakers for stereo output.

Step 3: Making the Battery Pack

I collected some batteries from old mobile phones. It is better if you could find same type of batteries in terms of capacity and chemical type. I suggest you to use laptop batteries( 18650 Li-ion batteries) as you can get up-to 6 cells if you crack open a battery. If using those batteries you will need a Li-ion protection circuit. But for this project i am using mobile batteries which has built-in protection circuit.

Before making any of the connections make sure all the battery voltages are same. If not, recharge them individually to 4.2 v.

Connect 3 batteries in Series to make a battery pack of 12 v. Solder wires on the battery terminals with some flux and solder wire. 3S1P configuration is used here. Note the polarity of each battery and positive of one battery goes to negative of another battery. The polarity of battery will be mentioned in the label or body of battery.

Note: Lithium batteries can be dangerous if mishandled. Do not Short circuit. Do not puncture the battery. Do not overcharge.

Step 4: Battery Recharging and Some Other Connections

A 12 V adapter can be used to recharge the battery pack. I am using a DC jack on the speaker unit to recharge the battery pack. Following are the connection details of Charging port, led indicators and switch. Please refer the circuit diagram.

The diode is connected to the positive of DC Jack to diode and the negative terminal of diode is connected to the positive terminal of battery pack to prevent the reverse flow of current.

Speaker is connected to the output of the amplifier. Use a good thick copper wires for this.

A SPST slide Switch is connect between battery and Amplifier Circuit. Blue LED indicates that the amplifier is turned ON. And RED LED indicates that the system is Re-Charging.

Connect the 1000 ohm resistor to the negative terminal of LED. Insulate all the connections with heat shrink tube to prevent short circuit.

Step 5: Amplifier Circuit Unit

It is important that you use a good quality amplifier for good sound quality and the quality of speaker is also equally important for good sounding Music system.

If you buy a new amplifier then it is easy to find the connection details. When you salvage from scratch pile, you need to find the proper schematic. For that all you have to do is find out what IC is used on the Circuit Board. Then the datasheet of the IC can be found on Google for reference, Refer the pin diagram and trace the connections on the salvaged circuit.

I did the same above mentioned procedure and soldered the wires and then interconnected all the components.

It is very important to check all the connections before connecting the battery and Audio source(here Mobil Phone). Once I had connected my mobile phone to wrongly wired circuit and had blew up the phone :( After that I double check the connections before connecting anything.

Step 6: Making the Casing and Assembly

I made the casing using the roll that comes with the packaging wrapper. I drilled out the required holds for LED, Volume knob, switch.

I made a ventilation hole by drilling a large hole in the casing and inserted a cardboard of cylindrical shape in the hole. Make sure to seal everything really well and make it air tight. The air has to pass only through the ventilation hole for best sound quality possible and crispier Bass effect.

I assembled all the components that were connected earlier using hot glue and super glue where ever required.

I found the mesh from old car speaker and cut it to the right size to fit my speaker. Mesh prevents any external damage to speaker.

I painted the casing black color and made design by cutting out the printed template. Later painted it yellow color for a cool looking design. It is nothing relate-able but looks Cool though!

Step 7: Adding Bluetooth to Any Speaker

You can add Bluetooth feature to any speaker possible. All you need is a USB Bluetooth audio Receiver and an AUX Cable and a USB power source like a laptop or phone charger.

Here I am using laptop as USB power source, Connect the Bluetooth receiver and connect the AUX cable to Speaker of your choice.

Establish the Bluetooth connection with your Smart Phone or a tablet PC to enjoy your favorite music anywhere, anytime! By doing this you can turn any old speaker in to high tech wireless Bluetooth speaker. Make sure your speaker and Bluetooth receiver does not share same power source.

Step 8: Done! Enjoy Your Music!

The Portable Bluetooth speaker build is Successfully completed. The Sound effect is really good for its simplicity. The Bass effect is crisp and is deep. The music output is very clear. You can watch the video for demonstration. The sound is loud enough for regular indoor use in a crowded room like a class room.

I tested the backup time to be about 6-10 hours which is good enough considering two of my batteries were too old.

Once I took this to my friends and they really enjoy the music from this as the sound is loud enough despite the noise of giggling and shouting crowed. I don't say this is the best but I am happy that I built one on my own and it costed me only peanuts to build this as most of the parts are reused from scrap yard.

If you have any doubts or suggestions regarding the build please leave a comment in the comment section below.

Thank you

HS Sandesh Hegde

Audio Contest 2018

Participated in the
Audio Contest 2018