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This is an easy way to tidy up cord that are too long or in the way. Great for the car or desk.

Step 1: Materials

USB cord for your device (Got mine at Dollar Tree)
Pencil
Blow-dryer
Tape

<p>Nice one, it's an old idea, but no doubt many of the youngsters may not of heard of it. A very useful technique in and around the workshop, where stuff gets tangled. <br>Steve (ex Plastics Engineer)</p>
<p>Thank You, I see the possibility's are endless, &quot;Jumper Cables&quot; maybe.?</p>
<p>Do you mean the kind you use to start one car with another? Because that wouldn't be a good idea...</p><p>It would be ok as long as you made sure they were stretched out before you used them but with the crazy amount of current they can carry you could quite easily melt the cables if they were used whilst still coiled. I wouldn't take the risk in case somebody used them wrong.</p>
<p>Yea I was just wondering it this idea would work with an extension cord for my power tools. That's a lot more than a USB cable but a very small fraction of what the jumper cable need to carry (up to 1,000 amps). Power tools 15amp max.</p>
<p>It is inadvisable to coil power cords in this manner.The reason being that thay carry AC current and not DC.</p><p>With AC circuits any coil acts as in inductor thus increasing the impedance of the coil so tnat the I(2) R losses become greater thus producing heat.</p>
A little physics is a dangerous thing. :-) It is not just you but all this talk about inductance is true but the effect is so small as to be irrelevant. Do you know how many windings are in a transformer? Do you know why?
WOW, I thought I was the only one that got past day three in electronics school. THE inductance is a joke at 60 hz and with both side of the AC cord in rhe coil the cancel the almost non existent effect.
<p>&quot;THE inductance is a joke at 60 hz&quot; Really? Just try running a marginally designed 60 Hz inductive load device ( read - most US products) at 50 Hz and measure temperature rise. I had one hour long chat with GE engineers about how to safely use a 60 Hz US model AC in India on 50 Hz supply. It was an eye opener. Even your low power transformer based AC adapters will heat up under these conditions. </p>
<p>A few microhenries at 60 Hz are not going to make much impedance. </p>
TRUE but it sounds like most if these guy took the short bus to electronics school and don't know a Henry from an O'Henry. Besides you have both sides of the cord there which cancel out. That is why you need a line splitter to use a clamp on ammeter.
<p>&quot;Besides you have both sides of the cord there which cancel out.&quot;. You are right. That is how Bifilar windings work to make non inductive load resistors. </p>
<p>no only a bit yES, but if you say the a cable on AC is no danger, your the little prick here</p>
<p>and for your info before you think again your OWN story's,like the Flinstones,</p><p>In a coil on a role an Carry hight watts and Amps.</p><p>They to temp messure iT.</p><p>But ONLY IN A LONG TIME IT WILL BE DANGERUS.</p><p>IS IT CLEAR NOW.</p><p>MY GOD WHAT A STORY MAKERS HERE</p><p>So no DC .</p>
<p>I was under the impression that USB cables carried DC, not AC</p>
<p>BOTH.</p><p>The battery charging current thru a USB cord is DC. Loading files thru a USB cord, that is AC. </p>
<p>True, but the AC is VERY low power, not like the AC from a wall outlet. So the losses would not be important. In fact, there are many off-the-shelf audio, video and USB cords that are coiled like this.</p>
The inductance of the coil is a joke at the frquencies involved. A little knowledge is a dangerous thing. Companies make money off this kind of ignorance. They sell ridiculoisly heavy audio cable by saying that audio only travels on the wire surface when this effect only occurs at fequencies millions of times higher than audio.
<p>Just what are the frequencies involved? </p><p>Consider that the cable may be used for a USB 3.0 data transfer. USB 3.0 is spec'ed to transfer at 5 Gbit/s. </p><p>Unless the cable is shielded, the air-core single layer inductor formed by the coiling can have significant impedance at GHz frequencies.</p>
<p>how do you think you got your DC, always need AC for it,is for charging or as a mains to DC</p>
They carry both. There are 4 wires. One pair carries 5 volts DC and the other pair carries data, which is definitely not DC. They sell coiled usb cables and this talk of the coil affecting the signal is utter nonsense. It is like saying that weighing yourself with or without a cash register receipt in your pocket will make a difference
Good point but everything is sort of AC when it is turned on and off. It is not so much &quot;alternating&quot; current AC &quot;changing&quot; current that causes the problem. Thus the arc welder example described previously. It also depends on what effect you are talking about. A coil will generate a magnetic field with DC. That's how a solenoid works.
Coiled AC line cords are a common item. The inductance of an air core coil of a few dozen turns at 60 hz is a joke.. Besides, you have both sides of the AC line there that cancel each other out. AC chokes are usually in the Henry range and you are talking about micro Henrys
Not all cords are cords are thermal plastic that gets soft when you heat it. Some are rubber that can tolerate quite a bit of heat until it starts to burn. You don't mean 1000 amps but 1000 watts The total srvice for my whole house is 200 amps. 1000 watts is about 8 amps at 120 volts AC line voltage.
wait, what? Why would they behave any differently when they're coiled? my jumper cables haven't even gotten noticeably warm to the touch with use
<p>It depends what you're using them for and how thick your cables are as they aren't all made equal...</p><p>Basic laws of electricity give the equation of P=IxIxR, Power = Current squared times the Resistance. A car's starter motor for a large vehicle can draw up to 600Amps so even with a low resistance ie. thick cables, you can end up with a fair amount of heat.</p><p>If two or more parts of the cable are touching each other then the amount of heat adds together.</p><p>It would probably be fine if you stretch them out before you use them or if you've got decent cables and a small car and it starts quickly but the worst case scenario could be pretty bad hence my advice against it. It's up to you if you do it, but I'd say better safe than sorry.</p>
This pencil trick us not going to work on heavy jumper cables. If the car doesn't start in a few seconds before the heat builds up you should not be cranking. I have boosted countless cars and trucks and never remember a cable getting warm Then again, I never use those 10 gauge bargain store cables. The insulation should be rated to handle the heat under worst case conditions. Jumper cables often have to be stretched full length to reach between cars and it would be stupid to waste cable coiling it just for storage convenience. This is a silly discussion about a non existent product.
<p>I'm still not convinced that IS the reason why you shouldn't do it. Resistance is based on material property*material cross-section*material length. You're not changing any of these things, it's still copper, the wire is still just as thick as before (or that's one hell'a powerful hair dryer), and it's still just as long, albiet coiled up now.<br><br>So, P=I^2*R is still gonna come up with the same thing.</p>
<p>I think he was mostly concerned with the cables having a reduced capacity to dissipate heat if some of the coils are touching. Still, it shouldn't have any *real* effect, unless you throw a blanket over the top of it or something</p>
<p>If you remember electromagnetism. <a href="http://en.wikipedia.org/wiki/Electromagnet" rel="nofollow">http://en.wikipedia.org/wiki/Electromagnet<br></a>That's why you shouldn't coil power cords, of any kind. It induces magnetic field that creates force opposite of the current that flows through the cord.<br></p>
Only AC. Not an issue here.
<p>when I was welding and bored, many years ago, we would wrap many feet of welding lead around a copper tube with some metal rod inside then strike an arc - 250 amps 26 volts DC and propel the metal across the room. Even better was 600 amps gouging current. </p>
<p>Correct! Do it if you like the idea. (Retired electronics engineer--44+ years in electronics.)</p>
<p>I liked the P=I^2*R part, but you lost me at &quot;fair amount of heat&quot;. The resistance in any standard jumper cables (6-gauge or lower) is so low you shouldn't ever feel them get hot.</p><p>All the same, I wouldn't coil them up like this because they'd take up more room in the car.</p><p>A nice jumper cable banter is here: http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&amp;Number=1738262</p>
<p>DC current</p>
<p>Cars run on DC, so inductance isn't going to be a big issue with coiled jumper cables.</p>
The inductance of the coil is a joke, even at AC and the idea that this pencil trick would work on heavy jumper cables is a bigger joke.
<p>you should learn a little about electricity before you make comments like this, sigh.</p>
<p>Thank You. = Voted. : - }</p>
thats a great idea aha but youd need one hell of a pencil
<p>Har!</p>
<p>When I was a &quot;youngster&quot; plastic had not been invented. Had not heard of this trick either.</p>
<p>Hey Bill, how old are you... 150? ;-) And don't you even remember the coiled cords on the wall telephone which enabled one to wander about the room while chatting to friends? </p>
<p>Wow, you are good, Emma! </p><p>&quot;The first man-made plastic was created by Alexander Parkes who publicly demonstrated it at the 1862&quot;.</p><p>I'm definitely old enough to remember coiled phone cords, but did not know how to make a coiled cord with a hair dryer!</p><p>I'm only 72.</p>
<p>I remember having a phone that did not have the coiled cord. I also remember the crank phone in the kitchen. We had the outline of the crank phone behind the dial phone until I was 12, and dad finally repainted the wall.</p>
<p>Those big crank phones had a pair of HUGE 1.5V carbon zinc cells... They were like gold in the 50's when I had a little .49cc glow plug plane motor..</p><p>Now they use a single LiPo the size of your finger at 3.7v</p>
<p>Yes Michael, I remember those large 1.5V cells, there were a bunch of old ones in our house when I was 10 years old. They had nice brass screw terminals. The batteries were dead; my friends and I cut them open and used the insides; for some reason we thought it was one of the ingredients to make gunpowder. Luckily we were unsuccessful.</p>

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Bio: I enjoy making things. My making them is usually based on necessity, the fact that it doesn't exist, and/or buying it pre-done would ... More »
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