Bluetooth and Wired Headphones Conversion (Improved)

Hi everyone!

This is an improvement of my last instructable: Bluetooth Headphones Conversion

This version includes the following changes::

• Wired connection via 3.5 mm plug added, ´cause we all still have something without bluetooth or the battery is dead.
• New charging sistem, with DC Jack Adapter

Also, there is a video, showing the headphones working. Enjoy!

Here is the materials list:

• Some old/broken headphones, with the audio cable coming out for one side only.
• Mini Bluetooth Audio Receiver (I got the TS-BT35A08 in DX.com for about 7 dls http://www.dx.com/p/ts-bt35a08-mini-portable-bluetooth-v3-0-edr-audio-receiver-w-mic-black-355910#.V_6kGH81GCg)
• A DC Jack Adapter (I got 10 pieces for around 4 bucks in DX.com http://www.dx.com/p/dc-jack-adapters-10-piece-pack-122746#.WBNiT381Fp8)
• Epoxy Clay
• A Micro USB Cable
• A 3.5 mm audio Jack to 2.1 mm adapter (I found this one on DX.com for 1 dollar http://www.dx.com/p/dc-2-5-to-3-5-minijack-cable-9819#.WBNnbn81Fp8)
• Thermofit / Heat Shrinkable tube
• Isolation Tape

Here is the tools list:

• Utility Knife
• Soldering Iron
• Drill
• Multimeter

Ok, first, we need to take apart the speaker on the side where the cable come out.

To prevent some damage between the magnet, the audio wires and the bluetooth, i put some isolaton tape over it.

Then, I split the plastic over the bluetooth chip and take it out

Now, cut the 2.1 mm tip, from the audio adapter, and using the utility knife, take out the plastic cover from the female side.

Use a lighter to get rid of the plastic cover on the wires to allow the solder wire to stick

We have 2 speakers and only one cable, wich means we have a left
audio wire, a right audio wire and one ground wire, wich conects both speakers on series. The audio jack from the bluetooth, has 3 pins from left to righ: 1st left audio, 2nd right audio and 3rd ground. The first and second pins could be used on any order, as long as the third pin remains ground

The hole for the audio cable was so small, that I could'n fit a female micro USB Port, so now, I decide to add a DC Charging Port on the side of the speaker, wich connects to the micro USB port.

This cable comes in 2 parts, one inside the headphone to conect the bluetooth charging micro USB port to the DC Charging Port (Lets name it Charging Cable A), and another one for the DC Jack to USB conversion (Lets name it Charging Cable B)

Charging Cable A

• Cut the plastic of the micro USB cable until the pins are exposed
• Solder 2 wires, to the 1st pin of the micro USB cable, and another to the last one.
• This is the right time, to drill a hole on the cover of the speaker, leaving access to the on/off switch.
• Also, Drill a hole on the side of the speaker cover, to hold the DC Charging Port

Charging Cable B

• The USB Cable has up to 4 wires, 1 red (mostly positive) and 1 black (mostly ground).
• Conect the Charging Cable A, to the Bluetooth Module USB Port and test wich one of the DC Jack it´s positive and ground

• Solder each USB cable, to the DC Jack

• Isolate the wires with shrink tube

The Female Audio Jack has 3 wires, just like the speakers.

To find out, wich one correspond to each pin, we need a male to male 3.5 audio cable, and the Multimeter:

• Connect one side of the audio cable, inside the female audio Jack
• Set the multimeter to find continuity and test each of the female jack wires, to each pin of the male jack
• Write down each par.

The Charging Cable A needs enough space to connect into the Bluetooth, and turn back to the DC Port hole. Use the utility knife to cut some material. Also, in my specific case, the space between the magnet and the back of the headphone case, was so small, that i need to put the batery next to the bluetooh.

After everything is align, use som epoxy clay to fix the bluetooth inside the case.

• Once the audio wires, are identified. insert them trough the audio cable hole, and solder them to the Bluetooth Audio Jack.
• Then, cover the pins with some isolation, like silicon, just like I did.
• To fix the female jack, put some epoxy clay, inside the hole, and push it back 'till the epoxy comes inside the speaker.
• Use a bit more of epoxy to fix the outside of the plug,
• Finally, just let it dry.

• Insert the DC Power Jack, trough the hole on the side of the speakers.
• Use a nut to fix it on the side.
• Solder one of the micro USB Cables, to the center pin of the DC Port, and the other one to the side pin of the DC Port.
• It Should look like the last photo

Now that everything is inside, we need some easy way to push the On/Off switch.
I came with the idea to use some transparent acrilyc with a small hole to cover the chip, and a screw inside the hole to push the button. Also, I add a thin layer of epoxy clay over the screw head, to prevent the switch to get stuck inside. Later, I place it over the hole and glue the acrylic piece in place.

We're done!
The bluetooth battery last around 6/7 hours of continuous playing.

Now, you can use the wireless mode with your cellphone or computer, and the wired mode with any 3.5mm jack device you allready have.

I hope you enjoy this Instructable improved version, to recycle some old headphones.
Please leave a comment or a suggestions, to improve it!