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In this Instructable we are going to make a solar wireless headphones that use bone conduction speakers to play music. This headphones are capable of control the multimedia player basic functions and also have a built in microphone to allow take calls.
The solar panel will provide an extra power boost, is not too much but is enough to give 15 extra minutes of music and recharge the battery while the headphones are off. The lipo battery itself can power the headphones for around 50 minutes. And also you can provide external power via de mini usb connector, when you do this you can continue using the headphones while the battery is recharging. The battery status indicator only will be on while the battery is recharging over USB, in solar recharge mode the led remains off all the time to save energy. The bone conduction allow to listen your music while you still hearing your surroundings, so this headphones are nice when you are outside and you want to continue paying attention to the external world.

This is a work in progress so there is a lot of improvements that can be done!

Lets get started, shall we?

Step 1: Materials

To make this fantastic build you will need this components:

  • Flexible 5v solar panel, small enough to fit in the headband.( my solar panel only generate 4.8V@22 ma)
  • Plastic headband. (the ones girls uses for the hair)
  • Aluminum tape.
  • Double side tape.
  • A sheet of thin craft foam.
  • Hot glue and of course hot glue gun.
  • Some flat wire.
  • Electret microphone.
  • Small 3.7v lithium polymer battery. Mine is 450maH.
  • 2 Bone conduction transducer (got myne from Adafruit, they are the 8 ohm small type)
  • A bluetooth audio module ( I used XS3868, but if you can buy a better one like the RN52 do it!)
  • Two small audio transformers (I used DA101MC)
  • Two 33 ohm resistors.
  • The rest of the electronic components can be seen on the Eagle designs that I include with the PCB and schematic. Most of them are SMD.

Keep in mind that this proyect uses SMD components, so be ready to solder this tiny things!

Step 2: Making the Boards

For this step you need to download the eagle designs from the previous step. And you need to make and assemble this boards. I am assuming that you know how to interpret the designs and get things done. So i will be short in this step.


Note: I used a JST connector for the lipo battery. The 3.6v regulator is not necessary, I included it for powering the bluetooth module but it give me a lot of brown out power problems.

Step 3: Getting Done the Tranducers

The first thing you get in mind when you receive the bone conduction transducers is that the wires are fragile. So I wrap the wires around the body of the transducer and used some hot glue for secure it.
Then I used a cross shape piece of foam to cover the transducer and protect it. Then I used some aluminum tape to keep in place the foami. Then I put a piece on double side tape in the other side of the transducer and braid the wires. Now you can solder the transducer to the amplifier board. Repeat this process two times, you will need to of this.

Step 4: Placing the Modules in the Headband

Now is time for remove the backing of the double side tape and start placing the boards. I make A little slot in the headband for the tranductor wires.
Place all the boards, but consider to save space between the boards for the soldering job. You need to be patient, this take a bit of time and effort. When you are sure of the placing stick it using double side tape. Don't glue the solar panel in this step, just save the space for later. This way you can pass the wires under the solar panel.

Step 5: Make the Connections

Ok. This part is probably the most challenging, you need to solder all the wires in place. Follow the schematic of the picture and use flat wire to get this done. Be careful!

Step 6: Finished!!! :)

And thats all! Congratulations, you build your own solar wireless bone conduction headset or SWBCHG for short ;)

Optionally you can use some ribbon or fabric to make a nice cover for the electronics.

Is time for some bone rocking, power it on and connect to your phone or computer.

See you the next time! I hope you enjoy it, if you have any question don't be shy and ask me ;)

Best regards,

Daniel Fernandez R.

hi..sir i want ask you something about this project
Hey, how bad is the sound leakage on these adafruit transducers? Likes can you hear it if someone next to you is listening to music with these? I know cheap bone conducting headphones have really bad leak, so if your in the same room, u sure gonna hear them. But expensive ones have likes none at all, you can listen to hellish volumes, ans no one will hear it if they dont touch you.
<p>Hi.</p><p>You definitely can hear if someone next you is listening music. At low volumes is imperceptible, but at high volumes you can hear what others are listening (maybe 3 meters away if you are in a quiet place) </p><p>Yes, the sound leak is high but for the price of these I think is just fine.</p>
Ok, cool!
<p>Loving it...we have our own Brand of Bone Conduction Headphones BUT these rock!! Loving the Solar part the most :)</p>
<p>Thanks!</p>
<p>Hey, have you done any programming with the xs3868 bluetooth module? I use that same one but can't get a serial connection to work between it and my computer.</p>
<p>Not yet, I know that you need to use SPP profile on the computer but I dont have idea how to do that. Maybe you can use device manager to see is there is a serial port on your computer when the xs3868 is plugged. </p><p>Also you should try to send some AT commands and see what happens.</p>
ok, I tried connecting using the RX and tx pins of my arduino board but with no success in sending any commands, my computer recognized the board itself (ftdi chip at least) but not the Bluetooth module so I'm guessing I may need something with rs232 capabilities. I'll let you know how that goes once I get the parts.
<p><a href="http://hackaday.io/project/2273-integrating-the-xs3868-bluetooth-module" rel="nofollow">http://hackaday.io/project/2273-integrating-the-xs...</a></p><p><a href="https://drive.google.com/file/d/0B2QngNWhTdRVOVRjT0taMkJJbEE/view" rel="nofollow">https://drive.google.com/file/d/0B2QngNWhTdRVOVRjT...</a></p><p>these two links are probably going to help you. I ordered my board, and i expect it to come in every day now. Hope this helps for you!.</p><p>BTW arduino has 5v rx and tx, and i don't think this board supports that. I think it only accepts 3.3v tx and rx. </p><p>Good luck.</p>
<p>Thanks for the feedback, I am going to check the links :)</p>
<p>Hi Lad,</p><p>This is great!! How did you make the boards? They look like they are made from cloth??</p>
<p>Hi, </p><p>Thanks! They are regular handmade FR4 boards, I used the heat transfer method (or toner transfer) to do it. </p><p>I place it in a way that don't compromise the flexibility of the headband ;)</p>
<p>For the bone Conduction transducers to function properly, is it necessary to use an amplifier? And what are the two small audio transformers (DA101MC) and the two 33 ohm resistors for?</p>
<p>Yes, it is. Thats because this kind of transducer use a lot of power, they need 1 watt to work properly. The audio transformers and the resistors are for audio signal coupling with the amplifier, the bluetooth module can only drive 40mW@32 ohm speakers so you need to amplify the signal. The audio signal ground is not to 0 volts, it is to 0.9 volts so you can't attach directly to amplifier ground instead the we use the transformer for coupling signal to ground and eliminate the noise if you don't do that. The resistor is just for simulate the resistance of the speakers, this audio transformers only have 0.75 ohm resistance so we need to increase it in order to prevent audio distortion.</p>
<p>Thanks, but where did you buy the amplifier? I can not find a good small one watt amplifier.</p>
<p>I used the TDA8551T, I like it because you only need a few components, the volume contro is digital, works at low voltages and the audio quality is great. I bought it on element14, but you can find it in digikey and mouser. Maybe Adafruit has something that can work for this project if you can't find this amplifier chip. </p>
<p>Thanks</p>
<p>This looks simply amazing! How does it sound?</p>
<p>Thanks, the audio quality is not high fidelity but it sounds quite well for a technology that is relatively new in the world of consumer electronics. The voice and bass sounds perfect but you loose some details listening music, specially high tones.</p>
<p>I'm excited to see where this goes in the future!</p>
<p>Amazing man! I would like to do it, I'll save money :P</p>
<p>Thanks! Please share your results when you finish them :)</p>
<p>Nice project...<br>I am wondering how the audio quality is, since I never tried bone conduction...<br>And what was the overall cost of the project and if you can give each part's price it would be nice..</p>
<p>Thanks, the audio quality is not high fidelity but it sounds quite well for a technology that is relatively new in the world of consumer electronics. The voice and bass sounds perfect but you loose some details listening music, specially high tones.</p><p>The overall cost of this project is around 60 US dollars, let me do the bill of materials and add it to the instructable. </p>
That would be great...
This is super cool. Very interesting
<p>Thanks!</p>

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Bio: I´m a guy interested in new tecnologies and the things that we can make in house with a few components and a bit of ... More »
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