Introduction: Bluetooth Earphone
Music is a great thing and it really help me in changing my mood. But since I don't want others to peep into my tracks nor I want to disturb my family members with my music, I mostly use those wired apple EarPods for listening music. Though EarPods are loud and sturdy, and provide a quality sound, the biggest problem with them is their cable. That hanging cable is really annoying, when I am trying to focus while listening to my favorite tracks. It gets tangled so easily when I am not using the earphones. Also, while watching movies or youtube videos, I can not go away more than 2 meters from my phone because of that silly cable. Since both of my phones do not have a headphone jack, I have to use a convertor each and every time, to plugin my EarPods to my phone. Buying those new AirPods can solve this problem but I don't want to invest in those $160 earphones. A bluetooth headphone will also do the job but as you know, after using headphones for quiet some time, your ears start paining. Finding out the solution of my problem, I came across this idea of building wireless earphones. Since I had a pair of old earphone lying around, I utilized them in making this DIY bluetooth earphone.
These earphones are a cheap alternative for those wireless headphones and are able to provide a really loud and quality sound, for a very less price. Since these are DIY earphones, you can chose the specifications and the capacity of the battery, as well as the type of earphones used according to your need. You only need some basic parts and soldering skills to modify your current earphones into a bluetooth earphone.
Talking about the project, it includes an old cellphone battery which power a bluetooth dongle present inside that red and chrome colored box. The bluetooth dongle used in this project is generally used in those car radio systems, which do not have a bluetooth functionality. In cars, the dongle is firstly connected to the lighter port and is then connected to the car radio system through AUX.
We are going to use this dongle in a similar way, but it will be modified by us in the later part of this project, to fit our requirements. A small switch is also connected to the dongle, to turn it on/off and an LED, to show whether the bluetooth module is working or not. The charging of the battery is done by a normal mobile phone charger. For the enclosure, I have used acrylic sheet, which is further coated with a chrome color.
The range of the bluetooth module is about 8 to 10 meters and the battery life is about 5 hours. Volume of these earphones can be controlled by your phone's volume rockers. Also, there is a clip attached at the back of the earphones which helps you in hanging it, at the back of your shirt.
The power pin or the pin from where your bluetooth module will get the power is located at the place where the male USB port was previously soldered. And the audio output pins are present at the place where the female Audio jack was soldered. Look one the above images to understand the thing.
Now take the slide switch or the on/off switch and connect its 1st pin to the pin 1 or vcc of the bluetooth dongle and the 2nd pin to the positive of the battery. Connect the ground of the battery to the pin 4 or the ground of the bluetooth module.
Now flip your bluetooth module and at the bottom, you will find a SMD LED. Use a multimeter and find out the polarity of the LED. Once you have found out, using a permanent marker, mark it on the circuit board so that you don't forget it later. Now warm up the solder joint of LED and pluck it out with the help of a tweezer. Take a full size green LED, and solder wire on its leads. Now with the help of those wires, solder that green LED to the bluetooth module keeping the polarity in consideration. Switch on the circuit to check whether the LED is soldered properly or not.
These are the parts that you require to build this project. You can buy them from a electronic store or from any online retailer. Description of all parts is given in later part of this project.
Bluetooth audio dongle
Mobile phone battery(Li-ion)
Female USB charging port
On/Off switch ( slide switch would be better)
TOOLS AND OTHER ITEMS:
Soldering iron along with some solder wire
Wire cutter and stripper
The main step of this project is connecting your earphones to your bluetooth module. Take your earphones and cut its cable to an optimum length using a wire cutter or knife. You should keep your height in consideration when doing so because a very short or a very long cable will create problems in future. Once you have cut the cable, use a wire stripper to expose the inner insulated copper wires. Inside the cable, you will find four wires of different colors. If your earphones do not have a mic support, there will only be three wires inside the cable. Generally the color of the wires inside the cable is red, green , blue and white(non-insulated copper wire). The red one is the wire for left earphone, green one is for right earphone, blue one is for mic and the white one is for ground. If your headphone has any other colored wire, its better you check the connection of that wire using a multimeter before connecting it to the cirucit.
Using a lighter or a matchstick, burn the nylon threads present inside the wire. Now using your soldering iron, tin the ends of the insulated wire. In the beginning, your solder will not stick to the wires but keep on the heating the wires with your soldering iron until your solder starts sticking to the wire. Its advised to use a good amount of solder otherwise you will face difficulty in tinning the wires. Ones done, connect the red wire to the left audio output of bluetooth module, green wire to right audio output, blue wire in place of positive of microphone, and white one to ground. Once done, switch one the circuit and you will be able to hear the startup sound of the bluetooth module.