Introduction: Secret Agent Earphones

Picture of 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

Picture of 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

Picture of 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

Picture of 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.


Bban (author)2015-02-21

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

Bban (author)2015-02-21

What if the phone cord has four insulated wires

ElCubano (author)2014-02-11

I used a headphone cord is that ok?

walamoonbeam (author)2008-07-10

is there a DIY way to actually make an acoustic ear coil?

raikut (author)walamoonbeam2011-12-03

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

rickfmdj (author)walamoonbeam2008-07-18

Phone wire is not good. I used hollow tubing only

leevonk (author)walamoonbeam2008-07-13

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

blaine1996 (author)2009-09-06

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

afink4 (author)blaine19962011-10-17

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

foxtrot4697 (author)blaine19962009-10-16

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

prodo123 (author)foxtrot46972010-03-29

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

mlincoln1 (author)2011-08-07


jpelletier1 (author)2011-05-19

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.

zootboy (author)2007-07-25

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

jaime9999 (author)zootboy2008-03-06

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.

DjProToJeeX (author)jaime99992008-04-11

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.

DjProToJeeX (author)DjProToJeeX2008-04-11

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.

jaime9999 (author)DjProToJeeX2008-04-14

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).

DjProToJeeX (author)jaime99992008-04-14

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.

DjProToJeeX (author)DjProToJeeX2008-04-14

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.

DjProToJeeX (author)DjProToJeeX2008-04-16

there never was any data that showed a constant short circuit. The only spikes we ever achieved were comparable to a stereo (3 contact) plug. and that was when audio was being out put and we were plugging and unplugging the headphones. but as i said at most times the spikes would be higher with a stereo plug then a mono (2 contact ) plug was in most applications. there never was any data that showed a short was ever occuring. If there was a short, then our data showed a stereo plug shorts a stereo jack all the while same as the mono plug. but in actuality are data shows there never is a short occuring in which is enuff to cause a short circuit that will "fry" a device if any. unfortunately im unable to participate with the group we have setup, today. As i fractured my jaw (mandibul) yesterday and need sleep for a week. OH THE PAIN being right never felt so painful.

zootboy (author)DjProToJeeX2008-04-27

Wow. Even I would never have gone to such lengths to prove I was right. Kudos to you, my friend.

computer_freak_8 (author)zootboy2009-06-12

Only one problem: It does cause a short!
I can almost guarantee you that all those stories are false. Anyone with even a little bit of electrical engineering experience will tell you that the best way to test for a short is to use a multimeter. I don't have a multimeter, so I did another test:
Construct a simple LED circuit. For the switch, use a stereo jack (female), and wire one side to the ring connector and the other side to the sleeve connector. When you insert a mono plug (male) into the jack, the LED comes on, because the sleeve on the mono plug shorts out the connectors of the stereo jack's ring and sleeve terminals.

It doesn't short. all a mono plug does is merges the positive and negative signal into one path way. the same output of power is still present on the ground. but the audio is only channeling 1 signal. the reason the load wont short is because of the grounding. easiest way to explain is this.

Stereo. u turn 2 taps in the bathroom on half way. the sink drains the water easy.
Mono. u turn 1 tap on full. which = 2 taps on half. the sing still drains easy.

the ground or the sink hole always has the same load on it.

Yes, it does create a short. What you are referring to is true if both the plug and jack (male and female) connectors are mono. This conversation refers to a mono plug (male) with a stereo jack (female).

ok stereo cable works like this TRS Tip is positive Ring is positive and Sleeve is Ground (negative) trust me it doesn't short

dj_nme (author)hoihoi1512009-07-08

On a stereo plug (or socket) the tip is the left channel, ring is the right channel and the sleeve is ground. On a mono plug there is no ring, the sleeve goes all the way up to the tip. So: if you plug a mono plug into a stereo socket, the sleeve on the plug will short-out between the ring contact and sleeve contact in the socket. If you don't believe this, go do it yourself and check continuity between ring and sleeve socket connections on a stereo socket with a mono plug inserted. The reality of the situation will then be instantly obvious.

hoihoi151 (author)dj_nme2009-07-08

mate im an audio engineer. i know how the signal and power is divided. left and right channels both contain positive signals and the ground is the negative path. it doesnt short because instead of the postive being divided into 2 channels it is pushed into the one. but the load on the negative end is still the same. its still the same amount of power being distributed through the circuit. its like having small rivers flowing into 1 big river. (stereo). or 1 big river flowing into a big river (mono). i have put mono plugs into stereo ports all the time and it doesnt short.

Like I have already said: When you are using a (male) mono plug connected to the (female) mono jack, you are absolutely correct. However, that is not what this conversation is about.

You agree that with stereo, Tip/Ring/Sleeve == +Left/+Right/-Both, correct?
And you agree that with mono, it is Tip/Sleeve == +Both/-Both, correct?


zootboy (author)computer_freak_82009-06-24

First of all, this is an OLD discussion. over a year old. But anyway... Yes, using a mono plug in a stereo jack WILL short out the right channel. The ground on the mono plug will make contact with both ground (the sleeve in T-R-S) and the right channel pin (the ring in T-R-S). The question is, does it matter? And according to these people's testing, it doesn't. It appears that most devices have smart pre-amps that prevent a short from blowing itself out, or that a short will not blow it out anyway. But if you're really that concerned, just use a stereo plug! Simple as that.

jaime9999 (author)DjProToJeeX2008-04-14

A picture is worth a thousand words, so here are some sketches that illustrate the problem.

Photo 1 shows how a stereo plug mechanically connects. Terms: Plug=male, Jack=female. The shaft of the plug contacts the hole of the jack, establishing the ground (-) connection. The tip of the plug contacts a metal finger deep in the jack, establishing one of the channels' + connections. A portion of the plug's barrel near the tip touches another metal finger, less deep in the jack, establishing the other + channel connection.

Photo 2 shows how each half of the plug/jack mate and keep the two stereo channels separate.

Photo 3 shows how if you plug a mono plug into a stereo source, the full shaft of the mono plug (lacking that special separate barrel section) ends up shorting out the channels amp output that with a proper stereo plug would have carried that channel's circuit.

DjProToJeeX (author)jaime99992008-04-16

your illustration could use a little work as well

jaime9999 (author)jaime99992008-04-14

whoops, + and - are backwards in the above illustrations.

leevonk (author)jaime99992008-03-06

works fine with my ipod, so feel free to follow this instructable if you have an ipod

leevonk (author)leevonk2008-03-08

I used a stereo jack, not a mono jack. I added a note to the instructable noting your concerns. Thanks guys

zootboy (author)jaime99992008-03-08

well said. just remember to get the right type of jack when you buy it.

Cartermarquis (author)zootboy2008-11-23

Right, just remember mnemonic for audio wiring: Red Right Ring. The Right channel is indicated by the Red wire(normally), and is the "Ring" of a Tip-Ring-Sleeve(TRS) connector. The left channel is the tip and the sleeve is ground.

computer_freak_8 (author)2009-06-12

This is a neat idea. I think I'm going to have to try this one soon.

Ph3nomin0n (author)2008-10-03

Ok I tried making this just like this instructable. but I ran into a problem... I am using a stereo plug btw. My Phone cord has 4 wires green,black,red, and yellow.. and on my plug I have red and copper, and green and copper. Obviously the red and the green go together but where do I connect the copper wires to.. Yellow? Black?

Ph3nomin0n (author)2008-09-26

I did this slightly differently with same results and less soldering. I simply cut the plug off the earphone I was going to put in my ear and soldered it to a broken earphone wire that I had lying around thus making the earphone cable longer. Then I removed absolutely everything from the inside of the phone coil cable and stretched it out and inserted the cable through one end and out the other. A little more work but less work at the same time... but very nice instructable, nicely explained and everything... 5/5

Ph3nomin0n (author)Ph3nomin0n2008-09-26

Forgot to mention I used the behind the ear piece from a pair of dollar store headphones that have a plastic part the hooks behind your ear... Just the plastic, the earphone was crap.

Mercenary Wubby (author)2008-08-02

Gah. I tried this, didn't work. Not adviced with small buds, highly unadvised, its also hard to solder for some reason, its almost like its not even metal.

tguerilla (author)2007-10-19

Man, phone wire is crap! What is with the fiber the copper wraps around? Or am i buying the cheap stuff? Anyone know better alternatives that will work with an rj-11 jack?

uberchoob (author)tguerilla2007-12-04

I got an idea: take the wire your old earphones or wire from some cat5 and pull it through the coiled telephone shielding. that would allow you to use very thin phone cable instead of bulky thick wire, and at the same time not lose sound quality. Am I just noob, or is this a good idea??

drummonkey92 (author)uberchoob2008-07-28

its hard to fit the jack end of the headphones through phone wire casing. also, i think that its the wire inside which holds the shape more than the plastic outer does

tguerilla (author)uberchoob2007-12-05

Cat5 wire sounds like it would work, it is much more solid. But then pulling it through the shielding may be trivial. I never thought about using it as scrap.

jaime9999 (author)tguerilla2008-03-06

Yes, but the reason coily-cords use that weird film-type copper surrounding little nylon fibers is that this construction gives the coils their needed flexibility and hense coily / springy -ness. Others [below] suggest using solid copper wire, of the sort in Cat-5 cable, but solid copper is ductile and holds its shape... consider all the arts-and-crafts (and probably instructibles on this site) made with colorful solid copper telephone wire. Thus using it here would cause the coil would lose its springiness, which is the whole point of the coiled cord. Rest assured, that even though the ribbonlike metal interbraided with the nylon cords seems weak and insubstantial, the metal bits can readily be soldered.

leevonk (author)tguerilla2007-10-20

yeah, the thin strings are pretty annoying, you can either A) carefully unwind the string from the copper or B) just solder as if it'snot there and it will get burnt off to a certain extent during soldering. I ended up replacing my phone wire with the wire from a broken rj-ll to cassette adapter I had, it's nice because it'slighter weight wire and no strings in it.

leevonk (author)2008-05-26

the middle metal segment/ring is a conductor for an audio signal. The thin black rubber rings in between the three metal segements are there to isolate the different signals.

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