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Picture of DIY Bluetooth Audio Adapter - BluFi

There isn't a single audiophile or a gamer who doesn't feel the necessity of wireless headphones, speakers etc. or simply, of wireless audio transmission. I also dislike the hassle my wired headphones present while trying to watch from a distance and this led to the inception of BluFi.

This adapter, BluFi, converts any audio accessory into a wireless audio accessory. Since it has an in-built TRS female jack, therefore any audio accessory having a male TRS/TRRS jack can be easily plugged into it for Bluetooth audio reception. For instance, your wired headphones can be made wireless by simply plugging its audio jack into the adapter and then pairing the adapter with the phone.

BluFi is based on XS3868 module which is powered by a 3.7V rechargeable lithium-ion battery, therefore you won' t have to worry about exchanging the batteries. It also contains a Female USB 5V DC output socket for powering any USB speakers directly through it. The TP4056 charging module has also been integrated into it for hassle-free and quick charging through our familiar Android smartphone chargers(USB-C port).

The reason why I preferred an adapter to integrating it into audio accessories is that this way, our expensive audio accessories won't be tampered with. I also needed something to convert my car's speakers to Bluetooth without any modification to the car(because I wasn't allowed to do so) and that's how BluFi came into being. Additionally, BluFi, being an adapter, is portable and much more compact.

Step 1: Gather Around Some Stuff

Picture of Gather Around Some Stuff
Stuff Required-2.jpg
XS3868 Bluetooth Adapter.jpg
Booster old - schematic.jpg

The requirements for this project are very basic. The only thing you require additionally is the XS3868 module which can be purchased online.

BluFi is the combination of two circuits, namely, XS3868 circuit and MC34063A DC-DC booster circuit. Therefore, I'll be splitting the requirements into two sections for better understanding.

Concernig the microphone, if you want to provide microphone input through your earphone or TRRS jack, ignore the GND connection of microphone in schematic and connect the MIC pin of TRRS jack to the resistor and capacitor as shown in the schematic without any changes."

XS3868 Circuit Requirements:

  • XS3868 PCB.
It can't be bought. We'll have to make it ourselves. The procedure is shown from the next step.
  • XS3868 module - 1 pc.
I had bought it from Aliexpress. This is the link.
  • TRS Female Audio Jack - 1 pc.
  • Microphone - 1 pc. (Optional)
  • Lithium Ion Battery (3.7V) - 1 pc.
  • TP4056 Charging Module - 1 pc.
  • Tactile(Push) Switch - 5 pcs. (Optional)
  • Capacitors:
    • 47uF -1 pc.
    • 220uF - 1pc.
    • 0.1uF - 1pc.
    • 2.2uF - 1 pc.(Optional, for mic)
  • Resistors:
    • 2.2k - 1 pc. (Optional, for mic)
    • 10k - 1 pc.
    • 470R - 1pc.
  • LED - 1 pc.(Optional)
  • Female USB Socket
  • Female Headers.
  • Slide Switch - 1 pc. (Opitional)
The switch is missing in the picture because initially I had planned to use terminal blocks for powering up the circuit.

3.7V Booster Circuit Requirements:

  • MC34063A Booster PCB.
The procedure to make it is covered afterwards.
  • MC34063A - 1 pc.
You can buy it from Aliexpress from this link.
  • 8 Pin IC Base - 1 pc. (Optional)
  • 100uH inductor - 1 pc.
  • 1N5819 Schottky Diode - 1 pc.
  • Capacitors:
    • 100uF - 1pc.
    • 10uF - 1 pc.
    • 1nF - 1 pc.
  • Resistors:
    • 180R - 1 pc.
    • 22R - 1 pc.
    • 12k - 1 pc.
    • 3.9k - 1 pc.

That's all for the requirements. Let's move ahead and start making the PCBs.

I'm posting the schematics for reference and modification purposes.

If you're unable to gather the materials required for the 3.7V booster, then alternatively you may buy this or this instead of making it. Even I had faced a lot of difficulty in finding the 100uH inductor.
krauser351 year ago

Microphone doesn't work.

What kind of cap is 2.2uF? Is it electrolytic or ceramic?

Someone mentioned about TL084 here :

How to use it?

Please explain more about microphone.

By the way for me pin 14 is for Play/Pause


UtkarshVerma (author)  krauser356 months ago
I've tested out the mic personally today and it works. I used an electrolytic capacitor(it turns out the polarity doesn't matter) and the mic was sending audio to my phone as expected. Therefore, to get the mic to work, simply refer to my schematic.
UtkarshVerma (author)  UtkarshVerma6 months ago
Upon further inspection, I have found that Cap- terminal should be connected to R2 and Cap+ terminal to Pin 4.
phebex1 year ago

are you already using a microphone? does it work?

UtkarshVerma (author)  phebex1 year ago

I had laid out the pins for the mic for later use but I haven't tested it yet because BluFi hasn't been in my possession. As far as I can remember, to use the mic, an extra circuit has to be used in between the mic and BluFi. You might also need to check if MIC has been enabled using PSKeys.

UtkarshVerma (author)  UtkarshVerma1 year ago

Oh never mind, I have already included that in the schematic. It should work considering mic is enabled in the PSKeys.

UtkarshVerma (author)  UtkarshVerma1 year ago

Just wire up the mic as shown in the schematic.

Hello, great work. I'm using electrect microphone and my sound detect on my phone. I made change into TRRS jack and using my headset/earphone. Speaker work, but microphone didn't work.
UtkarshVerma (author)  phebex1 year ago

Well, there have been issues with MIC for a lot of people and I haven't tested it out yet(because I know it'll take a lot of time, which I don't have currently). Sorry to say this but you're all alone in this.

Also, I'll update this Instructable for the mic instructions when I'm done testing it(however the testing won't be done soon, it is on my To-Do though).

Alright, I'll be waiting for a good news.
I'm also looking for information on the csr8645 chip, which is widely used for Bluetooth headsets in the market. There is very little information about this chip.
UtkarshVerma (author)  phebex6 months ago
I just tested out the mic today, and it works fine. However, there are a few things you should note:
- If you connect the mic alone directly as shown in the schematic, the mic will work.
- If you want to use your earphone's mic through a TRRS jack, then it won't work, because TRRS microphones share their GND with the Audio GND. Therefore, you will end up shorting the Audio GND of XS3868 with its Power GND, which is not a good idea.
"To use the TRRS mic, ignore the GND connection of mic in schematic, this way the mic will be powered using Audio GND." I've tested this personally and it works.
Good luck. Sorry for the long wait.


UtkarshVerma (author)  marc.deloor.51 year ago


Anshu AR2 years ago


UtkarshVerma (author)  Anshu AR2 years ago


OM SHANKERS2 years ago

It's really well designed work !!!

UtkarshVerma (author)  OM SHANKERS2 years ago

Thank you.


EdwardF20052 years ago

Awesome! I would really like to build one of these as I am a Gamer that wants wireless headphones!

UtkarshVerma (author)  EdwardF20052 years ago

Glad it could be of use to you.