Secret Agent Earphones





Introduction: Secret Agent Earphones


Easy way to make FBI-escque earphones. This is very useful if you ever want to listen to music but also have one ear free (for instance while biking in the city)

Step 1: Cut Up an Old Phone Cord

Cut the ends off an old springy phone cord.

get some earbud headphones, cut the earbuds off and cut the jack off.

you will need:

1 earbud
1 jack (stereo or mono)
1 cut phone cord
soldering iron

Step 2: Solder Everything Together

Some commenters have noted that it could be dangerous to your audio player to follow this instructable's instructions, mostly if you try to do it with a mono vs. stero jack.
I did this with a stereo jack and an ipod, and it worked fine, I've been using it for a long time, full volume, etc, no problems. So if you have an ipod and use a stereo jack it should be safe to follow this instructable. With other audio players it might work ok too, but who knows.

The diagram explains it all, the text might be hard to follow. To see the diagram more clearly click here TO VIEW IT FULL SIZE:

using a multimeter figure out which wires of the headphone jack connect to the two segments closest to the tip (or the single segment at the tip if it's a mono jack instead of a stereo jack).

solder both (or a single wire if it's a mono jack) of these wires to a single wire of the phone cord.

Solder this same phone cord wire, at the other end of the phone cord, to the wires (or wire if mono) on the earbud side which are the same color as the jack side.

solder the ground wires of the jack side to a single wire of the phone cord.

Solder this same phone cord wire to the ground wires of the earbud.

Step 3: Check for Continuity

check that the wires are appropriately connected using a multimeter. Make sure that there is resistance between the non-ground and ground wires (this resistance is the internal resistance of the earbud through which the wires are connected).

If everything checks out, plug it in and have fun.



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    I have a particular phone cable with four insulated wires. There's black red yellow and green.


    What if the phone cord has four insulated wires

    I used a headphone cord is that ok?

    i am also looking for an instructables for making an acoustic ear buds.

    Phone wire is not good. I used hollow tubing only

    what the hell is an acountic ear coil,are you talking about a speaker?

    why don't you just put one of the earphones in if you want to have one ear free? much simpler and doesn't require cutting anything, in fact it takes less effort than normal because you only have to put one earphone in

    3 replies

    Come on man that wouldnt be cool then you have one of those lame white headphones now you have a FBI looking headphone

    but then, it won't be an FBI type headphone

    Earphones, you mean.
    lol this reminds me of agents from Matrix

    Why didn't you just took a stereo headset and only use one side? Or just cut of the other side if it border you that much? Seems much easier to me.

    Just so you know, the tip of the stereo jack is the left ear and the ring is the right ear.

    6 replies

    Yes, which demonstrates a small flaw in this instructible. If plugged into a stereo source device, such as a walkman, ipod, or home stereo, don't build this using a Mono plug (don't follow the mono-plug wiring instructions). why? because a mono plug short-circuits one of the channels directly to ground (the plug barrel). Short circuiting a channel may damage some devices' amplifier circuits, depending on how they are designed. It certainly will waste energy. There is no (well, less) risk in tying two + signals together to feed a single load (the single speaker driver in the earbud). So, use a mono plug and follow the mono plug instructions only if you are using this with a mono device, like a walkie-talkie or AM transistor radio.

    ive never heard of that being the case. and when i got my degree in studio production they showed us how to do things like this rewireing headphones and more with headphone jacks including turning headphones into microphones. So do you have anything to backup the statement of mono plug shorting circuits. Cause im interested in that, like some data or something. I say this cause that cant be true, they make mono/stereo switchable headsets. so if mono shorts stereo and stereo shorts mono. How can they get away with making switchable headsets. That was like a early 90s sales scheme and is nothing but myth. im an audiophile and have seen mono headphonos used in stereo jacks 100s of times on 100s of setups. So ima need to see a blown ipod or walkman or something.

    i just ran to best buy bought a cheap pair of mono/stereo switchable headphones took them apart. and theres no fancy capacitor or any fancy switch it just severs the connection between the left ear piece. all the difference in connector will really do is make for less distortion if any is caused by using one over the other. but mainly the real difference is well monaural and stereo.

    Any headphone that can be stereo will employ a stereo (3-contact) plug, never a mono (2-contact) plug, so you are safe; no possibility of short-circuiting your amps (unless you specifically wire up a short circuit yourself).

    thats a good drawing but still unless i see a broken walkman or ipod it doesnt ever happen and create a short. I can understand why they said it in the early 90s and how it was a sales scheme. but if it was true wouldnt there be a broken one somewhere and at least 1 post on the internet contributing to that fact. not just something saying it does happen. thats why i even went and bought a mono/stereo headphone set just to see if that claim is accurate AND ITS NOT. i been trying with a mono plug for 3 days to try and blow a jack or amp with no luck. as a matter of fact today is the second day we've tested this myth on a series of different players with a ATS-2, we tested signal-to-noise ratio, total harmonic distortion, frequency response, and milliwatt power output (tested multiple ohms of resistance including the standard 30 in dozens of scenarios). nothing no shorts ever nothing to infer that this is true. we were even tryd to create a short by putting mono plugs in half way and short of all the way. we even moded a mp4 player and tried to overload the jack with a mono headphone plugged in and still nothing. So if you got some fancy piece of equipment that can compare to the read outs i have from a ATS-2 that can show a short. Im going to have to say its just a myth with no hard facts its just theory.. and when i get back from lunch were going to keep on trying to blow a mp4 player or any devices amp with a mono plug. for as long as we have the lab for which is for another 5 hours so. after today there will be 18 hours put on trying to prove that concept with no luck. were waiting on another piece of equipment which is coming from another college in the area and hopefully we can get more data. cause this myth is going to be busted by days end.

    we've also used for testing a series of audio precision meters starting with the ATS-2, and the 2700 audio analyzer and a Rohde & Schwarz FSU3 Spectrum Analyzer. and in 20 minutes were going to use a fsu3-k5-k7 setup to compile all of our data. cause all of us includeing a 20 year sound engineering proffessor believe this to be a load of bull and were going to put an end to it. if we cant get a one of a dozen ipods a modified ipod to have higher MW output. 4 walkmans, 2 computers with realtek ac97 onboard, and a dozen mp4 players from which we have in class for a previous project on sound quality. so if one of these cant blow, nothing will. were also planning on testing stereo recievers a couple onkyos a few sonys, and some of those cheapo 2.0 sets you get from walmart or something that are like 80 dollars. were gonna leave recievers for tommorrow. and wensday where we will try to test at least 20 of them. at this point im going to be shocked if something actually blows. and if we get something to blow everyone of us includeing are proffessor will goto school for the entire day in pink tutu's and dance the nutcracker.