Introduction: DIY Bluetooth Speaker

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About: A passionate hobbyist, skilled in building electronic projects and 3D printing, works as a mechanical engineer with an artistic flair. With a love for plants and Pokémon, this genius thrives on DIY projects, u…

I wanted to build a simple portable Bluetooth speaker. The design is easy to follow. I have used a 5w speaker driver with a 5+5W audio amplifier. For the battery, I used six 18650 cells (which can be reduced, I had old cells with average capacity) connected in parallel with 1s BMS. The speaker also has battery level indicators (Red - <3.5v, Blue >3.5v). The speaker can be charged using a 5v adapter (has a type C female connector).

Supplies

  1. 5W Speaker driver - 2Nos
  2. 5W + 5W audio amplifier board
  3. 18650 cells
  4. 1s BMS
  5. LED lights 5mm - Red and Blue
  6. BC548 NPN Transistor - 1No
  7. 1N4007 Diode - 1 Nos
  8. 820-ohm resister - 2Nos
  9. 220-ohm resister- 1 No
  10. Female USB type C - 1No
  11. Self-lock push button - 1No
  12. Push Button - 1No
  13. 3D printed parts

Step 1: Design and 3D Printing

I designed the enclosure using CAD. The enclosure has two parts, one for speaker drivers and another for mounting cells, amplifier board, charging and display board, etc. The enclosure also has external padding to protect it from impact. I printed the enclosures using PLA and the padding using TPU material.

Step 2: Eletronics and Assembly

The electronics are divided into two parts. One is the battery indicator and charging circuit and the other is the speaker amplifier itself. The charger indicator is made using a prototype PCB board. The circuit diagram is shown in the circuit diagram above. When the voltage of the battery drops to 3.5 v the circuit turns on the Red LED, and turns the green LED when the voltage crosses 3.5v

The battery is made using six 18650 cells, parallelly connect to 1s BMS. The input voltage for the BMS is 5v, so I have used a type c female connector, through which the Battery can be charged. To power the speaker on, I have used a small self-lock push button and to show the battery level, I have used a momentary push button.

The speaker driver is connected to the amplifier board as shown in the figure. The drivers are mounted using hole glue (mounting holes were not provided). I have used acoustic foam to absorb the sound waves behind the driver. This increases the quality of the speaker.

The bottom part of the enclosure houses a battery, battery indicator, push buttons, and amplifier board. The top part houses the speaker driver.

Step 3: Photos and Videos