Introduction: BluetoothBox for Stereo Headphones and Speakers
I love what my headphones, but a few weeks ago, my friend bought a new bluetooth headset, I intend to switch to bluetooth headphones. But I do not want to throw away the love of my headphones, so I got the idea make a small box, which I can turn my headphones into a Bluetooth headset.
This project shows how to convert all wired headphones or speakers to the headset or bluetooth wireless speakers with the ability to work at least 6 hours on full charge and being able to recharge without any complications.. It is open hardware project: BluetoothBox
Step 1: Intro
Before we get started we are going to need a little bit of motivation, take a look at these pictures and realize what you will be making.
This project could be complete by anyone, just a little electronic skills, you can make yourself a unique BluetoothBox. It only takes 3 days to complete the design and to share this project to you, and I hope this project can help you a lot.
Step 2: Materials List
I love bluetooth, short range hi-tech radio that can transmit all sorts of data. Bluetooth headsets are AWESOME because you can listen to music, game, or call your friends with no cord hanging around. You can connect this box to any bluetooth enabled device such as a tablet, computer, or almost any phone. There is NO DONGLE NECESSARY, and it only costs about 25$.
Here is what you need to make your BlutoothBox:
- Laser cut machine (Better that you should send the file to a laser shop for laser cutting machine). If you have a 3D printer, it will not have any big problems anymore. You can easily design a case for themselves at your disposal without calculating thickness of acrylic sheets. Unfortunately I do not have a 3D printer, it will come in the future :))
- Hook Knife Cutter PCB Copper
- PCB drill
3mm Screws Hexagon and Screwdriver
30-40W soldering iron with small tip
- USB charger
- Wired headphones or speakers (of course)
- PCB sheet: size 4 inches square or larger
- 200mA Li-ion rechargeable battery: 1pcs
- 0805 SMD Blue Led :4pcs
- 0805 SMD Red Led :1pcs
- 0603 SMD 10KOhm resistor: 7pcs
- 0603 SMD 5KOhm resistor: 1pcs
- 0603 SMD 0.5Ohm resistor: 1pcs
- 0603 SMD 1KOhm resistor: 6pcs
- 0603 SMD 4.7uF capacitor: 3pcs
- 0603 SMD 100nF capacitor: 1pcs
- 0805 SMD 10uF capacitor: 2pcs
- 2N3906 SMD transistor: 1pcs
2 pin SMD button: 1pcs
5-way tactile switch: 1pcs
Micro USB SMD Female connector: 1pcs
Thin wires: about 10 inch
5mm acrylic sheet (with any color you like)
3mm acrylic sheet (with any color you like)
2mm acrylic sheet :black
2mm acrylic sheet : white opaque
You can get all of materials on Ebay with very cheap price.
Step 3: Stereo Audio Amplifier Module
Audio output directly from the bluetooth module capacity is too small, so I decided to use a power amplifier module for powerful output signal provides speakers and headphones.
PAM8403 module meet my requirements, this module has a compact size, 3W output for both Left and Right 2 lines. This is a great choice for mini speakers, you can also use this module to build yourself a unique pair of speakers without spending a lot of time circuit design.
The input signal is connected to the audio ouput of Bluetooth module
Here are a few features of the module PAM8403:
- Operating voltage: 2.5V~5.5V
- Maximum output power: 3W + 3W (at 4ohm)
Noise ratio: 90dB
- Channel Efficiency: >90%
2 channels 3W amplifier with PAM8403
Output is CMOS BTL driver
Cannot change any component parameters to protect IC
The board can also powered by 5V USB power supply or 4 x 1.5V batteries
It is perfect for MP3/MP4/notebook
Dimensions: 0.91 in x 0.63 in x 0.08 in (2.3 cm x 1.6 cm x 0.2 cm)
Weight: 0.25 oz (7 g)
Please make sure the power supply is not more than 5.5V and please don't do reverse polarity for "+" and "-"; otherwise, it will burn the board.
Step 4: Stereo Bluetooth Module
And this is the most important component of this project: BC-05B BLK Stereo bluetooth module.
I've learned a few weeks ago about Bluetooth, and amazing to know this module. It is a completely flexible circuit board, you can make a lot of projects with it without any problems.
The assembly according to the manufacturer's diagram, you can build yourself a complete sound system without a lot of knowledge about them. Electronics is wonderful.
The size of the module is completely flexible, I have motherboards assembly and success right from the first time.
Here are a few features from the manufacturer:
BC05-B bluetooth stereo reception module main chip adopt CSR BlueCore5 MM design. With high integration, small volume etc, only with a little peripheral components can realize its powerful function. Can and have A2DP, AVRCP transmission and remote control protocol of any bluetooth source equipment (such as: with bluetooth phone, bluetooth stereo audio emission module, bluetooth adapter, etc.) to establish connections, achieve high quality stereo audio stream wireless receiving, and able to source player to realize the remote control.
BC05-B bluetooth stereo module to users with remote control button interface, work status indication interface, stereo audio output interface, microphone input interface.
- Class2 power level.
- Built-in lithium battery charging circuit.
- Strong noise eliminating circuit.
- Effective transmission distance is 20 meters.
- Minimum SMT packaging: 15 x21mm.
- Follow the Bluetooth V2.1 + EDR Bluetooth specification
- Have the SBC, MP3, AAC audio decoding function.
- Have A2DP, AVRCP high quality stereo audio transmission and remote control protocol.
- Embedded powerful Kalimba DSP data processor, complete all kinds of digital speech processing.
- All kinds of high quality bluetooth stereo headphones.
- All kinds of high quality bluetooth stereo speakers, sound.
- All kinds of high quality bluetooth wireless stereo audio receiving equipment.
It is wonderful. About A2DP protocol: The Advanced Audio Distribution Profile is a Bluetooth profile that allows for the wireless transmission of stereo audio from an A2DP source (typically a phone or computer) to an A2DP receiver (a set of Bluetooth headphones or stereo system). Such devices typically also support the AVRCP profile as well in order to allow for track selection and such. A common misconception is that A2DP support is available on all Bluetooth 2.0 devices, which is not the case, and that A2DP is only available on Bluetooth 2.0 devices, which is also not true. A2DP support can exist in older versions of Bluetooth, it just was not commonly supported.
Although this module has built-in lithium battery charging circuit, but I still have to use a different battery charge management IC to ensure safety for this module.
And to save board area as well as flexibility in control, I have used a 5-way switch. You can see pictures of it above, this type of switch is compact so it's flexible so I can design a circuit board easily. It has all 10 pins, including four pins Common, two pins Center to press down and four pins left for the remaining four directions (right, left, up and down).
On this switch, I press in the center to function Play / Pause, press to the right to play the next song, press the left to play the previous track, press Up to increase the volume, and finally press down to decrease the volume.
Step 5: 3.5mm Stereo Headphone Jack
Next is the headphone jack. I selected a 3.5mm headphone jack, it is fully compatible with all types of phone headsets and mini speakers.
There are 5 pins, but I use 4 pins, including 2 pins of GND, one for Righ channel, and one for Left channel signal. If you use a 2 pins rest, you should solder them into two mini speakers.
It would work like this: When you do not plug headphones into BluetoothBox, mini speaker to play music. Otherwise, when you plug headphones in, the speakers will stop and you will hear music with headphones. Headphone jack works as a mechanical switch.
Step 6: TP4056 Li-lon Battery Charger
If you are interested in rechargeable batteries, you will know the TP4056.
The rechargeable battery is completely complex, if you just powered on rechargeable batteries to the battery can cause damage, can cause your battery explosion.
The battery charger should have a complex circuit to manage current and voltage in each charging period. But do not worry, TP4056 provides you with an integrated circuit so that you can easily recharge your batteries without causing any problems.
You can get TP4056 as a complete module, just plug the battery power and you can do other things. But I want to redesign the charging circuit so that it fits in my motherboard. Just like circuit design for manufacturers in the datasheet, you can see the diagram above.
The TP4056 can work with USB and wall adapter and you can charge the battery up to 1000mA.
When the battery is not fully charged, a signal pins on the TP4056 shows you the status of the battery, I connected it to a Red LED. Once the battery is fully charged, the other signal pins will tell you the battery status is full, I connected it to a Blue LED.
Make sure you connect the right pins "+" and pins "-" of the battery in order not to endanger. The power charger is also important, you must ensure that your power supply in the range of manufacturers.
Learn more in the TP4056 datasheet.
Step 7: Schematic
I finished the schematic BluetoothBox. Simply right-click on the attached file, select "save link as" to download the file. You should open this file in Eagle version 6.4 or higher.
There is also a PDF file for anyone not install software Eagle.
In the schematic, I used 3 Blue LED to indicate BluetoothBox has been connected to the transmitter. I used 2N3906 PNP transistor to control the LED blinking lights, from signal of BLK BC-05 module.
Step 8: Eagle Board
And next is printed circuits. I've split the circuit into two parts, one for USB and headphone jacks, one for the other components.
There are three holes for positioning the circuit board. All components are arranged closely together to minimize the size of BluetoothBox.
Step 9: Home Made PCB - Part 1
I like to make printed circuit boards at home, it saves cost and easy design changes when there is an error in the circuit diagram. But it's not really nice, of course.
There are many different ways to make printed circuit boards at home. You can find easily on Instructables, just search.
I used two layer circuit boards for optimal circuit design. However, you can still use a layer circuit boards because you can wiring in the bottom layer.
In this step, I show you how to cut the printed circuit boards by Hook Knife Cutter PCB Copper. You can get this tool on Ebay for cheap. Also you can use with an iron ruler, do not use plastic ruler, it is too soft and you can cut into the ruler. haha
Another way is you can use a hand saw to cut boards.
Step 10: Home Made PCB - Part 2
Next is printed PCB file. Remember mirror Top layer
After you have finished washing printed circuit boards, you should drill with drill bits 0.6mm for Via holes.
Step 11: Acrylic Case Design
I have also designed a case for BluetoothBox by acrylic. I chose 5mm and 3mm acrylic sheet to make borders, and 2mm acrylic sheet to cover.
The design is simple with Corel Draw, but I have to carefully calculate the size to fit panels circuit board placed in the case.
To compound the acrylic panels together, I have more design 3 screw holes for each sheet of acrylic. Inner diameter of the hole is 2.5mm, after laser cutting, it will fit into the screw to rotate. However, the hole should be 2.7mm.
Next, I designed a ring to the light of the Blue LED light can penetrate, creating a bright circle when BluetoothBox enabled. I chose acrylic sheet opaque to perform this task. This kind of acrylic seems only half the light through it, and keep the remaining half light up in it, so you'll see a faint light effects, looks very nice.
There are 3 positions for the light from the LEDs to the acrylic circle. You can see in the picture, the location alternating between the screw holes.
Finally, I designed the cover for BluetoothBox. There are two the cover, one on top and one on the bottom. The hole "+" is the place you can press a button to control BluetoothBox. I also put the screw holes and charging status light. The words "USB" and "Headphone" is where you will plug into the micro USB port for charging and headphone jack.
I also do not forget to add names to it, both the top and underside. The text will be laser engraved with fully automated.
Step 12: Laser Cut
Here are a few pictures of my acrylic sheets after laser cutting at a store.
The cut is completely accurate and smooth, looks very nice.
Step 13: & Laser Engraving
And here is the the cover of BluetoothBox after being engraved with laser.
Step 14: Test Assembly
Can not wait anymore, I conducted a test assembly for BluetoothBox case. It is better than expected. haha.
Printed circuit boards are placed fitting in acrylic coronary. Unable more beautiful :))
Step 15: Make Charger and Headset Holes & Paint It!
I forgot to cutting holes for the headphone jack and microUSB port by laser cutting machine, because the holes are horizontal versus acrylic sheet so I can not see the design of it, it's a big mistake. So this hole must be created by hand.
I used a hand saw to thin thickness can be easily cut. Be very careful when doing this, because I have make the last 3rd of the rod is not broken.
And now I spray painted the acrylic case. Let's paint any color you like and I chose red. I like the red color combined with black acrylic the cover, look very nice. When the Blue LED lights up, looks even more wonderful.
Step 16: Soldering
I can not find any material to Via holes through the two layers board. So I decided to use the resistor legs to do it. The resistors have very cheap and I did not feel wasted when leaving few resistors.
After soldered the hole via, I soldered on the circuit line to protect it from oxidation. Now it looks nicer.
Step 17: Testing
I soldered all the components on the circuit board and finally soldered the battery to test.
Make sure you connect the right pins "+" and pins "-" of the battery in order not to endanger
- First, press and hold the Power button for about 3 seconds, the Blue LED will blink rapidly to indicate your Bluetooth board should be connected.
- Next turn on Bluetooth on your phone (make sure it supports A2DP), wait for it to scan the device for a few seconds, you will see a device called "BLK-MD-BC05-B". That's it. Stay connected with it, if required to enter the PIN code of the device, it is "0000". After the connection is completed, the Blue LED will blink slower to indicate your Bluetooth board is connected.
- Your Bluetooth board was really ready. If you want to turn it off, hold down the power button and wait a few seconds, the Blue LED will be turned off completely and Bluetooth board has been shutdown.
If unfortunately, you can not start the Bluetooth board, may your battery has run out. Take a fully charged battery and start over. If you still can not start, you should check that the circuit board.
Step 18: Assembly Case and Board With Screws
I use the hex screws to attach the acrylic layers together. Acrylic rings are fragile and brittle, so be careful when you screw.
The screw has an outer diameter of 3 mm.
Step 19: Fully Assembled
Here are the pictures that I show how the components layout to fit the case.
The bottom is panels motherboard, next is the battery, on the top is the circuit board includes the microUSB port and headphone jack.
Step 20: Test Again
Once fully assembled it will look like this. I checked again to make sure the bluetooth connection is absolutely fine.
Step 21: Charge and Headphone Jack
The rechargeable battery is needed for you to use BluetoothBox many hours.
Plug one end of the USB cable into the USB port on your laptop or charge your phone, plug the other end into the microUSB port, the Red LED will illuminate to indicate battery is charging.
After about 1 hour, when your battery is fully charged, Blue LED will light to indicate you need to disconnect the USB charger cable.
Step 22: Battery Life
I checked three times the battery life time, BluetoothBox used continuously for 6 hours after you fully charged, open at the average volume.
This is true for predictions, Bluetooth molude energy consumption is very low, when you do not play music anymore, it will automatically reduce power to save energy, wait until you play music again. So if you forgot to turn off BluetoothBox, you will not lose much energy.
Step 23: Wear It and Enjoy!
Plug the headset, wear it and enjoy your BluetoothBox, can also connect it to a mini speaker to have a larger capacity. It can fit to your jeans pocket comfortably
Now you can turn all of your audio device into a wireless audio device.
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