DIY- HOW TO MAKE WIRELESS HEADPHONES

Once you've decided to make your own wireless headphone you need some knowledge about what we are going to do. First of all you need a headphone (An old one or which you are using). The headphone should have enough inner space (I mean to say that when you open the headphone the stuff "The radio receiver module" which we are going to install in in fit in easily). You have to buy a small radio receiver module be sure to use the smallest with auto or manual tuning. Now what we are going to do is install the radio module inside the headphone and then tune it to your Emitter's frequency and grab some of the controls of the radio module out of the headphones so that you can tune it without opening the whole headphone again. Now we move on to the Emitter, you have to make your own Emitter. It's a simple Electronics project. The circuit consists of one 2N2222 or BC547 transistor (You can use one or the other depending on the availability, But i prefer using a 2N2222 transistor) used as a base amplifier which amplifies the audio signals form your computer or T.V. and converts it into FM signal. The emitter's frequency is between 87.5 to 108.0 Mhz (Common radio frequency) and can be tuned to any frequency by changing the value of the 20-40 picofarad variable capacitor. Now FYI it's rage in not good up-to 3-4 rooms or 5meters so i my view you won't need a license for the frequency usage. You can emit any kind to audio signal from T.V, Computer, MP3 player , Mobile Phone , etc.

This is a cheap and best project i had ever made. As far as i think, To buy all these stuff together (Excluding the headphones and the tools used) you may have to spend 10 - 30 dollars in india it's will go to 1000 rupees. The radio receiver module generally comes in 10 dollars maximum and around 500 rupees. All the electronics stuff is worth 8-10$ and 250-300 rupees. The male & female jack and the wire's and the antenna will make a bill of 10 dollars. And if you are going to buy a new headphone please buy the one with good internal space then it will charge you around 10-20 $.

General tools

• Pliers ( For pealing the insulation from the wires)
• Screw drivers : Four head and two head (For opening the headphone & for casing the transmitter or emitter)
• A pair of scissors (For cutting the wire and other uses)
• Pencils & Eraser (For marking the board and other purposes)
• A cutting blade (For cutting the board)
• Multimeter(For measurements of resistance and continuity )
• Hot Glue GUN(For sealing purposes)

Soldering Stuff

• Soldering iron (For making the emitter).
•  A wet cotton pad  (For cleaning the tip of the soldering iron).
• Some soldering flux (For making the soldering smooth).
• Soldering wire of different gauges.
• De-soldering Pump (For sucking solder).
• Brush or a tooth brush (for Cleaning the board).

Now that all particular you need  . Once you collected all these stuff now you be ready to buy some Electronics stuff.

1. Electronics Part
2. Wires and jacks.

Electronics Parts

• 3 * 10K Resistors (Lead one code : Brown , Black , Orange & SMD Code: 103)
• 1 * 5.6K Resistor   (Lead one code : Green , Blue , Red & SMD Code : 562)
• 1 * 50 - 120 ohm Resistor (Lead one code: Green , black , black  To Brown, Red , Brown & SMD Code : 500 - 121)
• 3 * 0.1uf Ceramic capacitor (Code:104 , If you are willing to use a SMD capacitor you need to test it by a capacitance meter because Generally there is no code written on a SMD capacitor except some like i have.)
• 1 * 4.7 picofarad Ceramic capacitor ."This is and unusual capacitor if you can't find one use a 15p & 7p capacitor in series or you can make you own pair having the net resistance of 4.7p. FYI If you are putting the capacitors in series follow this ""http://www.electronics-tutorials.ws/capacitor/cap_7.html"" page to know how to calculate the net capacitance. " (Code : 4p7 or 4.7)
• 1 * 20-40p variable capacitor "The picture is not shown because i don't have one so i used a 33p capacitor. " (the code is : 20 ,21------50. )
• 1 * 0.0047uf Ceramic capacitor (Code:472)
• 1 * BC 547 OR 2N2222  Transistor.

Wires & Jacks

• 1 * Small tunable or automatic tunable radio module with 3v power supply. YOU CAN USE THIS ONE "http://www.ebay.com/itm/3-portable-uscan-radios-small-hand-held-/310720153283".
• 1 * Male 3.5 mm jack .you can buy it from here "http://www.amazon.co.uk/electronics/dp/B000Q6JR1Q"
• 1* 3v rechargeable battery. (Use as small as you can with good stand by power.) You can buy it from here "http://www.ebay.in/itm/Tiny-3V-Rechargeable-Coin-Cell-Button-Battery-MS621F-MS621FE-Very-Small-Seiko-/280743174845"
• 18 - 22 gauge  enamelled copper wire of length 20cm.
• 1cm dia. spool to wind inductor upon.
• 1 * 2.5 * 2.5 Prototyping board or called Multi-Purpose PCB.
•  A long thin copper wire and a 3 core wire.
•  1 * 12v Male & Female power jack.You can buy them from here : Female"http://www.ebay.com/bhp/12v-female-connector" / Make"http://www.ebay.com/itm/10pair-12V-Male-Female-DC-2-1-x-5-5mm-Power-Plug-Jack-Adapter-Connector-for-CCTV-/400545050623"
•  2 * FM Antenna or a hard long wire.
• One USB male connecter.You can buy it from here "http://www.alibaba.com/product-gs/564447272/USB_2_0_4pin_A_SMT.html?s=p"
• 2 * Small Switches.

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Now you have all stuff you need. It's time to move on and start making the emitter. The circuit is very easy to make .But if you want to skip this circuit making step you could also buy one FM emitter from here:http://electronics-diy.com/store.php?sel=kits&sub=fm_transmitters. If you do so no need of making the given circuit. Now move on to the circuit: This is a one transistor circuit . Before making you must draw a rough diagram.Now you have to go for power. This emitter can be powered by a 3-6v battery or a USB 5.0 V constant voltage for powering it with USB  you have to use a USB 2.0 male plug and it's polarity is given above in the image.(Just click on the images for magnifying the image)Solder the plug in the prototyping board and be sure about the polarity. Now make the circuit with extra care if you are using SMD'S.Connect the 3.5mm jack with a 3-core wire and solder it on the prototyping board being sure about the negative terminal of the jack goes to the ground of the circuit. and the two other wire will go to the input of the circuit. .Now you are going to make the inductor. This inductor is the most curious part of the circuit.This inductor is winded by a 18 - 22 gauge wire and there are four turns and the antenna is tapped at # 2 turns and the antenna is connected to the tapped wire . Initially there are Three wires coming out from the inductor .The two at the end are connected to the circuit and the middle one is connected to antenna If you are an beginner just know that a 18 gauge wire is around 1.024mm in diameter or please refer to this link:http://en.wikipedia.org/wiki/American_wire_gauge.You can use a long wire or small antenna for the antenna.You emitter is ready . Use a mobile phone FM application and check all the frequencies. You will get your frequency. I had uploaded the video .You can make 4p7 capacitor by putting capacitors in series e.g:15p :: 7p.Now you have finished making it and then you can case it so the inductor does not catch any damage i have used and angry bird MP3 player's casing.The image is given above.That's all the emitter is complete.

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Now you are on the final step. All you have to do is install the radio module in the headphone.First , grab some thin copper wires and cut them into pieces .Then Open one side of the headphone ( Note: Different headphones have different methods of opening their cabin.) where the wire is connected to and see if there is some space in the headphone or not if so make a hole yourself.Now you will see three wire.Take you radio module and open it too.There you will find the 3.5 mm female connecter. Now solder wires on the female connecter's leads there will be three (But it may happen there will only be two leads which are connected to the circuit.)now connect them to the headphones input lead.Now keep the battery and the switch in series and pass it by through the hole for the input jack and then solder the switch (So that the power can be switched on or off from outside.) but not the battery . The battery will stay inside.Now turn the board over you will see two push-buttons not at the back you will see four leads on each of them . Now solder all the four four leads with wire. Now take two push-buttons and one on-off switch and solder it on the a small prototyping board and connect all the four leads coming out from the push button to the small push button board  you had made before very carefully and respectively but before soldering pass the wires out from the headphone ..Check all the connections very carefully . The switch on the small prototyping board is the power controller switch .Now you can also take out the positive and the negative terminal out from the battery so that it can be charged again. Now you are ready to use. Tune the headphones to the emitter's frequency by bringing the headphone close to it and scanning. If you are using a manually tunable radio module solder all the wires coming out from the variable capacitor or inductor and pass them out from the headphones from tuning it. If your radio module is not good enough you can put an antenna . For doing this there are two ways  : First if you have a pre-installed antenna  just solder a wire and put and antenna outside. Secondly if your radio module does not have and pre-installed antenna then solder the antenna at the audio out 's ground of your headphones because this ground is used and an antenna.  Here you go. Enjoy!

• Every time before using the headphones keep the the  Headphones close  to the emitter and then tune it (This is for those who are using the auto scan radio module).
• Keep the volume of the emitter low to ensure good quality of sound.
• It's better to use a rechargeable battery for the headphone or receiver.
• Use good quality headphones.
• You can also use a common household radio to listen to it by tuning the radio to it's frequency.
• You can use your headphones as a radio to listen to other station.
• Please vote for me.
• If you have any further questions be free to ask me.
• If there is some mistake in this instructable please inform me!