Introduction: DIY Bluetooth Headphones

Picture of DIY Bluetooth Headphones

Tired of ripping wires on your headset? Don't like the feel of being "chained" to your computer? Then you came to the right place!

This is a quick DIY project. It can be done in less than 2 hours if you are familiar with the topic, and no more than 1 evening for a complete newbie.

The main objective is to modify your wired headphones into stereo bluetooth headset with the ability to work at least 6 hours on full charge and being able to recharge without any complications.

This frustrating activity (I'll let you know why in a minute) requires minimum tools/materials and at least some experience working with hand tools and soldering iron.

ATTENTION: The new version of wireless headphones is available here

Tools:

  • PH0 and PH00 Philips screwdriver
  • Rotary tool or small grinder (I am using a $20 grinder bought from China)
  • 30-40W soldering iron with small tip
  • Wire cutters or some old scissors
  • LiIon Charger

Materials:

  • Victim headphones with enough space inside to hold the battery
    (mine is an old beat-up Sennheiser hd 201 with 24Ohm speakers)
  • 3.7V LiIon battery$3.00 new (I am using really old Nokia BL-5C so it is free)
  • 1mm wire (preferrably 4 different colors and at least 1m each) $0.??
  • 3.5mm Female Jack connector (mountable, not the ones you solder on PCB$) $0.30
  • 3.5mm Male Jack $0.30
  • Switch $0.30-$0.50
  • BLK-MD-SPK-B Bluetooth module$10.00

Additional materials:

  • Solder
  • Soldering flux
  • Electrical tape
  • Hot glue w/ dispensor or just SuperGlue

Step 1: Preparations

Picture of Preparations

Disassemble your headset. You may need to take it apart completely in order to modify wiring.

Select one earpiece, which will hold all the active components, including battery and Bluetooth module.

Run a pair of wires through headpiece. You may need to drill some holes and use some glue to hold wires in place. Fortunately I had a nice thick padding on it and everything fit nicely around it.

If your headphones have hinges, then you really need to avoid guiding wires through moving parts. The best way around is to drill a hole right in the middle of the "arm" and make a matching hole in the earpiece housing (see pictures).

Step 2: Power Connector and Switch

Picture of Power Connector and Switch

Use your grinder to make a hole large enough for your power switch. I am using a round switch with latches, so i don't have to glue it. Do the same for 3.5mm Jack connector.

Important notes:

  • Make sure you leave enough space for other components.when installing power switch. If you drill too close to the edge of housing, you may damage it or the speaker won't fit.
  • Drill holes in small portions, because high friction from rotary tool will cause plastic to melt and burn.
  • Make sure the switch sits firmly in the socket, because you don't wanna end up pushing it inside and breaking the whole thing
  • If you did cut too much plastic - use hot glue to hold switch in place

Step 3: Speakers

Picture of Speakers

On the active side solder two ground wires and one active speaker wire. One ground connection will go to the second speaker, and the other two wires - to Bluetooth module.

The other side only needs to be connected to wiring in your headpiece. You may also assemble and mount it (we are done here).

Step 4: Connecting Bluetooth Module

Picture of Connecting Bluetooth Module

The first image shows the pinout for BLK-MD-SPK-B module. We are going to use pins 3,4,5 for audio output and pins 12,13 for power.

Solder all pins as shown in figure 2:

Pin 3 => Speakers ground

Pin 4 => Speaker L active

Pin 5 => Speaker R active

Pin 12 => Power Switch (Battery +)

Pin 13 => Battery -

PCB contacts on this module are really small and there is a high chance that you'll have to redo this part several times. Make sure you don't overheat solder points, because they are easily damaged. I had to perform a little restoration after accidentally scratching off the ground connector.

Every soldering operation on Bluetooth module damages contacts even more, so once it is done - you may not want to take it apart. If you feel that contact points are a bit loose - you can cover them with a little bit of hot glue or just use nail polish. Tape this contraption to the outside part of the earpiece housing with electrical tape, but keep it just below the board(where wires start).

Step 5: Final Steps

Picture of Final Steps

Solder 3 wires to the battery. "+" and "-" are always marked. The middle one is used to determine whether the battery is charging(blue wire on the picture). Attach all three wires to the power connector and then extend "+" wire to the second leg of the power switch.

Once done - mount the power connector (3.5mm jack) into the hole you've drilled for it and start assembling.

Make sure you don't block the Bluetooth module.

If your battery is loose - stick it to the back side of earphone housing and put a little hot glue to it's sides. Do not overheat the battery, because it may stop working or explode!

Test power connector and power switch, before putting everything together.

I've used my old phone as power supply, because I only had one spare 7.5V adapter, which happened to be a charger from my battery-donor-phone =)

I'll try to come up with more permanent solution in a few days, but this would do for now. Charging only requires a steady supply of at least 500mA at 3.5-4V.you can use any charging device or power supply(just don't use the middle wire from the battery), but you won't be able to see whether it is fully charged or not. There is also a danger of overcharging the battery (shortens it's life and may cause overheating).

Step 6: Testing

Picture of Testing

Once the battery is charged, unplug your headphones from power supply.

Enable bluetooth on your phone, tablet or computer and scan for audio devices. While scanning, flip the power switch on your freshly made headphones and wait for connection. In case there is a popup window asking for a Pairing PIN: it is "0000".

Wait for drivers to install. At the end you will hear a short bell from your headphones, which means you are connected.

If you are unable to connect, try to reset headphones and scan again.

That's it for today.

Good luck and enjoy life without wires!

P.S. Almost forgot the most important thing! After the initial test run my 8 y.o. battery was able to power this device for almost 10 straight hours (I don't like to turn it up that much). And this is only 1000mAh!

If you are going to use a new 2400mAh battery, you will get much more than that. Maximum current consumption with 16Ohm speakers is about 150mA per channel, so in theory you will get no less than 8 solid hours of rocking and banging on full volume until you loose your hearing.

Comments

pfantastic made it! (author)2015-03-16

I made a universal bt receiver (based on your schematic) instead of headphones. I used a 4.7v digital camera battery. Thanks for sharing the knowledge! I'm going to set up everything with bluetooth now.

DarrenO2 (author)pfantastic2016-08-21

+pfantastic - so you are saying that you set up a camera, such as a web cam? The idea i am thinking on is setting up cameras around my home, but would it be better to have them as wifi and connect them with my computer or would the Bluetooth work better?

silentbogo (author)pfantastic2015-03-16

Awesome!

I actually got the idea after seeing something similar: the store I'm usually buying my parts from had a stereo-receiver based on this module and a Class D audio amp.

Dwargh (author)2016-12-07

Great i'ble!

Would it be possible to add in a microphone?

corbin1950 (author)2016-08-22

Hi Guys, just an added thought you can buy a complete Bluetooth module with built in battery, charging port and charge indicator for around 10 to 20 bucks on ebay and this way you have all in one package. Now the one I'm showing you is an older one with the earlier USB charging port but the newer ones have the new micro USB port. Some come with a female audio jack and some with male audio plug. Point is, you can save a lot of room in whatever project you are doing like headsets. I did this with a Bose headset.

chemacky (author)corbin19502016-11-17

Have you got a link? Or a part number? Anything?

corbin1950 (author)chemacky2016-11-17

hi

don't have exact part number but you can look on eBay under "Bluetooth receivers" or just Bluetooth there are lots of them online prices are pretty cheap too. I have bought a couple to use on a portable boom box to be able to send music from phone for example. all of them are usb chargeable and easy to use.

canklot (author)2016-10-01

i have hc-06 but its have soldered a board and its have gnd 5v tx rx state en ports. İ dont want to desolder it how can i use it ?

here the image

HowToGuy (author)2016-09-13

Is it possible to connect the two speakers using two bluetooth modules? If so please make an instructable on it.

jaldomir (author)2016-09-01

Hi . Why do not you put a microphone electrect too?

juanvi (author)2016-08-27

Dont you need an amplifier?

tyler roberts (author)juanvi2016-08-30

not for standard headphones. only audio-fools would use headphones with such high impedance that an amplifier is needed to hear anything.

juanvi (author)tyler roberts2016-08-30

Thank you, I understand. How do I know if I need an amplifier for a given impedance?

tyler roberts (author)juanvi2016-08-31

unless you paid several hundred dollars for "audiophile grade" than you likely wont. check the speakers inside the headphones for 4 or 8 ohm (ohms use the Greek capitol letter omega https://en.wikipedia.org/wiki/Omega)

KarenW50 (author)2016-08-22

I have a set of bluetooth earbuds that I hate and a set of wired over the ear headset that I love. Can I rip the guts out of the earbuds and use them to wire the over the ear? These are not heavy duty Beats just cheapies I picked up at the "Just Over a Dollar" store, so if they get screwed up I don't care. What do you all think?

ricebean (author)KarenW502016-08-26

Yes you can, there may be a difference in ohm values, but not enough that it would concern you. I have done it quite a few times and achieved great results.

brandonm59 (author)2016-08-22

I have a circuit board I took out of a bluetooth speaker it has an amplifier,bluetooth, a port to charge,an on off switch and is the size of your thumb. The problem is it too powerful for headphones. Is there anything I can do. A smaller battery? Resistors?

Spotman (author)2016-06-07

what about 18Ohm speakers or headphones? I tested a 3.7v 500mAH battery (it wasn't charged enough) and it gave the same volume and power, but I don't know much mAH my headphones use.

GuilhermeD6 (author)2015-10-09

Hello.

you got some success with the microphone?

kittyk3 (author)2015-09-28

MattisM (author)2015-09-25

For everyone who needs more details about the module (like vol +/-, play/pause/ mute buttons, ...)

http://www.elecfreaks.com/wiki/index.php?title=BLK-MD-SPK-B

Ali AsgerM (author)2015-09-14

Hi can i use this BT module directly with any large speakers? I have a 5.1 system at home and i want to make them wireless. I can wire the female 3.5mm jack at the left and right pin of the BT module.

will this work?

MattisM (author)Ali AsgerM2015-09-25

Basicially yes, BUT this modul is stereo, so you'll have only two channels, not 6. This means that it wont be possible to have an different output on the front and backspeaker (music is mostly stereo anyway). If you want stereo on let's say only the front you just need to connet the BT-module to the green jack (or the black if you want only the back) or even both if you want back and front. Connecting the subwoofer will be a bit more difficult bcs you'd need 2 diodes if you dont want to lose the stereo.

anupak (author)2014-08-26

I have used the same module for adding bluetooth capability to a old stereo system. I referred to http://www.elecfreaks.com/wiki/index.php?title=BLK-MD-SPK-B for the pinout. The module itself has a LIPO charge controller. Instead of connecting your the charger to pin 12 , connected the external power source to pin 10. The module will charge the battery. I have not tried this yet (was planning to do it later).

silentbogo (author)anupak2014-08-26

Thx! I'll try it out today.

I was trying to find a charge controller to finally retire my old cellphone, but this would've been just as expensive, as buying an external Li battery charger where i'm from... I was already thinking about re-purposing my arduino nano to monitor the charging process (check the output voltage 1/sec).

DadaSauce (author)silentbogo2014-09-05

I wired the on board charge controller (+USB to CHG, battery + to VBAT) and it looks like it started charging my battery(used my 850 mAh battery from my old Samsung cell phone). I also wired the two on-board LEDs (BLED and RLED). They give you info on if it is connected, waiting for connection or charging. I will keep you all posted on how it works over time.

silentbogo (author)DadaSauce2014-09-07

Cool! I rewired my charging loop too. Seems to work fine. I'm also trying to figure out how to utilize serial connection, because I still have enough space there for an Arduino Pro Mini :)
The only thing I need to do is to make a small PCB to surface-mount this module. Soldering wires directly seems to ruin it more and more.

Giga93 (author)silentbogo2014-11-17

Hi, i just got the BLK-MD-SPK-B and I want to use the charge function, I want to use an old phone battery and I want to charge it trough mini or micro usb. Can i connect the 5V usb supply power to CHG? or do i have to use a resistor? I couldnt find a datasheet only thing I found: operating voltage is beween 2,7V-4,5V.

And i read that it is possible to change the bluetoothname and pin by connection the module TXD RXD pins to a serial adapter. Is there a way to change it over bluetooth?

genetic inception (author)Giga932015-05-28

also, txd n rxd are transmit n receive so blue tooth device can be wireless: smart tv; sync audio light show, etc... Not everything is Bluetooth yet.

genetic inception (author)Giga932015-05-28

no, programming can only be done serial to computer

DadaSauce (author)silentbogo2014-09-07

My battery (850 mAh) got charged overnight through the module, and it kinda agrees with the module chip - OCV 3860 - specs (10-150 mA programmable charge current).

For the soldering, I cannot agree more. Actually I'm right now making the PCB as I want to implement the volume control and a few other perks on the module into my headphones.

This guy was nice enough to make the Eagle library and share it online:

http://waihung.net/bluetooth-audio-blk-md-spk-b-ea...

how do you wire the rled n bled indicator lights?

DadaSauce (author)silentbogo2014-09-05

Try these from Ebay,

http://www.ebay.com/itm/121410081227?_trksid=p2059...

or if you can wait longer you can get them dirt cheap from Aliexpress:

http://www.aliexpress.com/item/2pcs-lot-1A-dedicat...

genetic inception (author)2015-05-14

Thanks, everything seemed difficult so I had to work slowly. in the end, everything seemed simple to do. I did connect the on/off switch on the positive for the amp and the charger, this wasn't correct, but their was no feedback. Must be on to charge.

I re-soldered the battery pos/neg direct to the charger: Now I can charge the battery with the system off, but there is feedback when amp is on while charging. Basically, either listen or charge.

I already bought the amp so I connected it, however it is overkill and the duality of it is either headphones at low vol setting or party speaker system.

My bluetooth has not come in yet, still waiting on DX.

AspireGreatness (author)2014-11-10

Could someone show me where to get some of these supplies online, or a store I can find some of these things at?

I get my parts from DX.com

They have free international shipping and so far I had no problems with these guys.

Shipping usually takes ~3-5 business days in US and Canada and no more than 3 weeks for Europe and others.

Where are you from?

dxsoul.com also has good shipping and parts.

I've been buying parts from DX for over 6 years now. Probably one of the best asian suppliers out there ))

So, two days ago, I found that amazon had everything I needed, tried to order, one of the modules along with all the capacitors will not ship to Hawaii, tried other types of capacitors, still no dice. Very strange?

You can order capacitors from Digikey or Newark. It will be much cheaper.

As a last resort you can go to radioshack.

The US. So it should be quick, then?

In US you actually have a lot more options: Radioshack, DigiKey etc.

Plus you can order original stuff from adafruit and others!

Oh, that's pretty awesome! And also, for the project, I can/should remove all the original wiring? I don't know how to get into the speaker to put in new wires, they are Sennheiser HD 419's, if that's helpful to help.

419 are pretty much the same, except they already have wiring between speakers. All you need to do is remove the audio cable and attach speaker wires to Bluetooth module instead. The rest is very similar.

Oh, I already removed all the wiring because it was screwed up anyways :T I'll just have to rewire it then, thank you for the help though! I'll probably be back with more questions

jackal0206 (author)2014-10-13

I tried to make this too, ran into some issue, if anyone could provide some advice it'd be appreciated. I have everything hooked up, when I turn the power on I can hear the power on tone loud and clear, so does when I connect and disconnect my phone to it. However, when I music playback on my phone through bluetooth, the sound comes out choppy and has a lot of static noise. Any idea what might be wrong and how I could debug this?

silentbogo (author)jackal02062014-10-14

Make sure your ground connection is not loose and that it is connected properly(see pinout on Step 5).

jackal0206 (author)silentbogo2014-11-06

Thanks for the help. I have identified the problem, I think I got a broken module. However, now that I have replace the module, while idling I can hear a constant high pitch noise coming out. Does anyone have the same issue?

silentbogo (author)jackal02062014-11-07

I have this for only 4-5 seconds, before headset goes to waiting mode.

If it's presistent - check the ground connection once again.

jackal0206 (author)silentbogo2014-12-15

I discovered something interesting, but I can't explain why. I have a 12v power supply split to feed a amplifier and a 12V to 3.7V voltage regulator based on LM317, then 3.7V to feed the Bluetooth module. The module's audio output then goes into the amplifier's input. This is the configuration where I get a lot of noise from the Bluetooth module. if instead of splitting the 12V input, I run the amplifier on 12V input while running the Bluetooth module on a 3.7V power supply, the sound is clear and there's no static noise while the system is idling. I am thinking sharing a power rail is what caused the noise, but I don't have the background knowledge to explain why.

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