Convert Speakers to Bluetooth-speakers

Recently, I bought a pair of really cheap speakers. It took power from USB plug and audio input was through a 3.5mm jack.

After using them for some time I realized that these speakers were limiting freedom of my smartphone.

Solution- Bluetooth speakers.

Lets get started.

Step 1: Short Video

Here is a small video summarizing all steps.

Step 2: Understanding Speaker's Interface

In order to modify any hardware first we need to understand it. With the help of few screwdriver and some muscle I managed to take out PCB of the speaker.

Speaker's PCB-

PCB contains 2 audio power amplifier one for each speaker. Towards left, we have pads for VCC and GND. On upper side of audio power amplifier, we have pads for terminals of speaker. Audio power amplifier IC used on this PCB are Texas Instrument's LM4871T 3W audio power amplifiers. Towards right we have pads for audio input. On the back side of PCB, we have volume control knob and a decoupling cap.

Step 3: Bluetooth Stereo Adapter

To add Bluetooth functionality, I bought a Bluetooth stereo adapter. It took power through USB port and outputs audio on a 3.5mm audio jack. I opened it up to look at its PCB. IC used in this module was BEKEN's BK3254 and module was named as BT-163.

Step 4: Figuring Out Connection Between Speaker's PCB and Bluetooth Module

I connected speaker's 3.5mm jack to Bluetooth module and used my multimeter's short functionality to figure out connectivity between pads of speaker's PCB and Bluetooth module.

I marked names of corresponding pads on Bluetooth module using a marker along with Vcc and Gnd pins of USB port.

Step 5: Altering Connections

Now that connections were figured out. I used wire stripper and chopped off wire connecting to audio input of speaker's PCB. Conditioned them a little bit and soldered them to corresponding pads on Bluetooth module.

Next I removed USB connector from Bluetooth module using a desoldering braid and soldering iron. Once it was removed, I connected Vcc and Gnd terminals of BT-163 to Vcc and Gnd terminals on speaker's PCB. With all soldering done. I secured all connections using a glue gun.

Step 6: Putting Back Together

Finally, I tested operation of the circuit and it passed quality check without any problem. So I placed everything back inside the speaker case and that was it.

Speakers converted to Bluetooth speakers.

Thanks for reading.

Comments

[Jimbo251]

This is really nice. Thank you.

Is there ever a way to have a stereo pair of speakers, each with a Bluetooth module, one for left; one for right and space them a few metres apart without audio cables?

[inder678]

can send the link to buy bluetooth module. I search it but can't find any result.

[miniProjects]

https://www.amazon.in/gp/product/B01NBOYJAU/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

[kevinmaker2018]

Good job. Someone can get something from here.

[miniProjects]

thanks

[etmilosk]

Are you able to pair the BT module with more than one phone at a time?

[garrettg7]

most Bluetooth chips can only handle one phone or audio source at a time, so you can not simultainously connect and play audio from diffrent phones, however if you connect one phone the Bluetooth module isn't "locked" to that phone.

[miniProjects]

that is true. thanks for replying

[garrettg7]

Nice job! Very good work with the multimeter on determining connections, just a suggestion though, it might be a good idea to make annotations on some of your photos so that you can show readers what you are doing from photo to photo.

But really, great work! keep on making these and teaching others your findings and methods! :)

[miniProjects]

thanks

[leshemeli]

I love your creativity an imrovisation!

[Wingloader]

You got my vote!! Favorited.

[Luke Wilson]

Same.

[miniProjects]

thanks

[miniProjects]

thanks

[CharlieC34]

Excellent! What a great idea. Thank you, I will give it a go