MagSafe for the Rest of Us: A DIY Magnetic Power Adaptor

We all know that one of the most common places for a laptop to break is its power adaptor. The combination of being directly attached to the motherboard, heat, and constant moving and shifting leads the connector to become loose and sloppy. Eventually the connection stops working altogether. Apple has solved this problem on their laptops by use of a magnetic power adaptor, unfortunately for us they also patented the idea.

This is my version of a magnetic power adaptor for an Acer 1410 laptop, You should be able to modify the steps fairly easily for work for any laptop though. It is effective, easy to build with common materials, and takes the strain off of the internal connection and motherboard. It also holds on well enough to not come off unless it is supposed to.

Edit: There have been some changes to the design, mostly involving using thin copper foil in place of aluminum duct tape. There were heat issues involving the aluminum tape, these issues have been resolved by swapping out the aluminum tape for copper foil. Thanks to instructables members jeff-o and CyberBill for their insights and suggestions.

This modification should be completely reversible and do no harm to the laptop or original power adaptor.

Please always take your time to work safe and unplug the power cord and laptop battery.

A big thanks goes to breath for his original ThinkSafe instructable located here:
ThinkSafe: A Magnetic Power Connector for Thinkpads

Step 1 Tools and Materials

You will need:

Tools:

Pliers
Wire cutters
Scissors
Flashlight
Matchsticks (to apply epoxy)

Materials:

Neodymium Ring-Shaped Magnets (enough to cover your adaptor plug with some overhang)
Wire Studs (to fit into the power socket)
Steel Washers (asst. sizes, make sure your magnets will STICK to them)
Thin Copper Foil (Note: aluminum duct tape has too much resistance)
Electrical Tape
Two-Part Epoxy Adhesive
Nail(s)
Calming Incense (to keep you sane while working with the fiddly bits)

My design for building this adaptor changed many times throughout the build due to trial and error, it is best to start out with too many pieces and then narrow it down to what you actually need than to be stuck without a part you really need.

Cost Breakdown:
Magnets: $2.45 each
Wire Studs: $1.65 for 10
Epoxy: $5
Copper Foil: $10
Various Washers and Nails: $4
Incense: $1.95

Total Cost: ~$32 CDN

Comments

[sbengtsson]

You're all wrong

http://www.pcworld.com/article/116572/busting_the_biggest_pc_myths.html

[MRedu]

Not bad. I've come across this problem before where the connector on the power adapter splits and frays and then you end up having to buy a whole new power adapter!

[fazgard]

Great Concept.

Seriously, great idea.  I've replaced many a laptop motherboard power connectors over the years.

My only concern is the magnets.

Magnets next to delicate circuitry = bad.
Magnets inadvertantly wind up too close to the hard drive = data corruption.

If the connector came off (as designed) and you set the lappy back down (or got to close to) the magnets, you could easily corrupt your hard drive... or if you set it down with the magnets too close to the bottom of the motherboard unpredictable system results - as the magnets will play havoc with the low voltage signals that make your compy tick.

  I'll have to break out an old junk lappy and try to 'break it' with rare earth magnets.

Great idea!...  but be really really careful.

[kenwarf02]

Some of the strongest magnets around are PART of the Hard Drive! Very strong magnets are what allows the arm to be so fast and accurate when scanning the drive to recover data. And then there is an electromagnet on the read/write head of that same arm that creates all the data on the hard drive. So the hard drive is crazy in love with magnets... they make it work in every way!
Putting magnets on the power tip is not going to do anything bad unless you make it wrong and short out the power cord.

As for those going back and forth about Apple vs. PC... Get a life and a new hobby. If you enjoy picking fights and bitching about everything, go get married! Then you can do all that in person and leave real comments on the "SUBJECT" at hand to the rest of us. All this page should cover is the instructable, parse out problems and calm the fears if they are in deed unfounded fears.

[ibarnett52]

sounds like your the one that needs to get alife

[thinkdunson]

wow.

ok, the magnets and electromagnets that are part of the hard drive are in very specific places, and under very tight control.  i would love to see your face after you stick a magnet to the outside of your hard drive and then try to start up your computer.

in the case of a macbook, the magnet is in the computer, not the cord.  so they can put the magnet in a very specific place, far away from the hard drive, add some magnetic shielding around that small spot to shield the electronics behind it, and not have to worry about it at all.  having it stationary, inside the computer, is very different from having it on the cord that you might carelessly drape across the top of your laptop while under the desk, plugging it in.

[zack247]

first of all, who the hell is going to even bother putting a magnet on top of their hard drive? what purpose is there for that?

and second, the magnets don't do a lot of damage, if any to electronics. unless you are stupid enough to put a magnet on top of a microchip wondering wat it'll do, magnets wont do any permanent damage to electronics.

now take a couple of examples;
1: if you have a ds im pretty sure you know what happens when you put a magnet by the power switch. i do. it turns off the ds, a when you move the magnet away, it turns back on. just thinking it was closed and opened again. NO HARM DONE

2: what about magnetic sensors, magnetic alarms and magnetic doorbells?
its pretty sensitive circuitry, yet magnets are VERY close with absolutely NO sheilding. (strange... isn't it...?)

3: as for cell phones, i dont know. im sure it'll have the same effect the ds has, or it'll malfunction or turn off. but that is because there is a lot of metal in a cell phone, and a lot of delicate electronics you wont find anywhere else

now, are we clear?

[thinkdunson]

 there's no reason to get angry, kid.
"who's going to bother putting a magnet on top of their hard drive…"
i'm sorry i even started this conversation with you, as you are obviously a child.  i assumed you would understand that i was giving an example of something you should obviously never do because everyone knows that magnets will erase magnetic media.

there's a difference between electronics, and magnetic media.
you're taking examples of things you've seen work, and coming up with childish conclusions.  just because one thing can come close to a magnet and not be damaged, doesn't mean everything can.  a hard drive and a reed switch are two completely different things.

ever put a magnet close to a CRT tv?  it distorts the picture horribly.  well, there are closely calibrated electronic devices in there that can be pulled out of whack if you do that too many times.  i did it too many times when i was young, and the picture stopped returning to normal.  so i for one will not be taking the chance that there's something in my laptop that might also need to stay calibrated and might be sensitive to a magnetic field.  

so, to anyone who doesn't think he's albert einstein's long lost great grandson, i would advise you to be careful with magnets around a computer.  chances are, 99% of the people that try this will be just fine, but you never know who's gonna be the unlucky one.

[zack247]

okay, thinkdunson, i can tell when someone wants to be left alone in the corner with thier red, so i guess i might as well leave you alone.

and why put magnets on a tv?

im not gonna be the unlucky one. because unlike thinkdunson here, im not gonna bother putting magnets on electronics and hard drives that contain all of my information. you can, but i sure as hell am not

[sqeeek]

Zack, I think his point was that this instructable is not going to affect your computer in a bad way. Sticking a magnet on your 'micro chip', or near one for that matter, is not going to hurt it. Sticking a magnet on the side of your computer is not going to affect the hard drive. Why not? Because in 11 years of computer repair, I have never seen a laptop in which the power adapter was right next to the hard drive, or any other components sensitive to magnets.

Thinkdunson, nothing wrong with being cautious, but I've never been able to cause magnetic damage to a hard drive with a magnet this small. They really aren't that powerful at a distance. This is why the magnet doesn't go "SNAP" together from 3 inches apart. Even setting your laptop on the cord, I doubt it would hurt it.

But if you're worried, maybe consider drilling the iron shielding from the back of a shielded speaker magnet, use that instead?

[zack247]

i have something i would like to add on:
macs use this same method for their power plugs, users sometimes will end up leaving their power plugs laying quite close to the hard drive, the macs all work just fine.

[Fieldownage]

Okay zack247, no offense intended, but you're way out of line.

First of all as thinkdunson said "there's a difference between electronics, and magnetic media" and then there are differences between magnets, their behaviours around objects and strengths of their magnetic fields. You're trying to prove your point without proper evidence and without studying the objects first.

And to clear the matter of HDDs and magnets, The data on hard drive is organized and "written" with magnetic forces, as well as removed. For example, corporations have their hard drives "cleared" because of the possibly secret data, so they use magnets to completely "clear" the HDDs.

[fazgard]

You guys are funny.

The laptop is not shielded on the bottom for high strenght magnets like these to come into contact with. .. if you read what I was saying, be careful of magnets being under or around the hard drive  it if the connector comes loose (as it will, since it's desinged for this) , and then you set the laptop down on it.

Try it out.

Back up your data first tho :)

As for the electomagnetic radiation that is all around us, the feild strengtt diminishes exponetially as the distance increases. The laptop and circuitry are designed and shielded to negate this normal background radiation.

As for putting magnets near computer circuitry, weeeell . .it's too long of a discussion, so I say, power it up and try it out withsome old hardware. You wil lget unpredictable resulats, and if it gets near the Cmos circuitry, .. (haha - reflashing corrupt cmos is a blast. try it out sometime)

As for al lthe other things that you mention, they are Designed and shieled in the way that they aree constructed, and, ofc, they don't hold data in very tiny magnetic fields on a spinning platter.

25 years in computers and electronics jsut telling you that it's a great idea, jsut be careful since it can corrupt your data, or damage your mobo.

But again, don't take my word for it... it's unpredictable results at best.  Take a running hard drive and place a rare earth magnet under it and see how well your data holds up :)

No reason forthe flames, guys - but if your flaming, sorry, you don't understand any of this digital design and should take a class or two:)

Cheers!

[sqeeek]

Lol yeah... So, shield the plug or something.
Actually, isn't the PC in question an EEPC or nebook variant anyway? Get an SSD ;)

In all seriousness though, I've never been able to damage a mobo with a magnet, Except for CMOS I guess. Otherwise, nothing does much. Maybe temporary issues due to magnetism interfering with inductors on the board, but even that usually just causes power issues and resets it, fixed by power off and BIOS reset if anything.

I guess if you're worried you could magnetically shield the plug... Or figure out where the CMOS is on your laptop. On mine, as far as I can tell, the CMOS chip is abt 3mm under my right hand. Not somewhere that's likely to be damaged if I set it on a magnet.

Not trying to shoot you down or anything, I agree - no flames :)
Just proposing solutions:
1- Find the CMOS, if it's in the middle of the laptop under the keyboard, like it usually is... probably not going to be an issue, I wouldn't worry too much.
2- Shield the magnets. Many small speakers have a shielded magnet on the back, rip that off and use the shielding or just use the whole thing.

Idk, what u think?

[NiftyJunk]

Hard drives have cases made of a metal that shields against magnets. You would need a VERY strong magnet to damage your hard drive from anywhere outside of your computer. That said, it never hurts to be careful.

[moorea7]

Reminds me of the old 5.25" joke... Having some unsuspecting victim pinning them to the refrigerator with a fridge magnet.

[sitten_duck]

Out of curiousity, how difficult is it to remove wirestuds from the power ac adapter. The stud looks like its all the way in there, and it would be a nightmare to get it stuck in there or accidentally damage the powerjack trying to pull it out.

That happened on my old laptop. The powercable got ripped out and it loosened the center prong in the ac adapter. When I went to plug my powercord back in, it pushed that center prong all the way into the computer, and kept it from making contact with the powercord. That laptop had JUST been given to me by my sister. In the end I found out the only way to fix it was to do major surgery on the motherboard and replace the powerjack, something beyond my skills and beyond the skills of most everyone I knew.

I just bought this Laptop this week, It's a really nice laptop, I need it for college and there is NO WAY that I can afford to replace it. It's also the first laptop I've had since I destroyed my last one going on 5 years ago now. I REALLY don't want to break it. Now I fear something similar happening where I rip out my power cord and damage the system of my new laptop, but I don't want to inadvertantly cause the very situation I am trying to avoid.

Is it safe, or does anyone know how they can make that wire stud assembly a little safer?

[luisazmouz]

MacBooks have that :-D

[Justin D]

the inside of my power port is to small to have the pin attach to the ground pin and have the plastic piece slide down into it , so what i have done is rolled a piece of copper foil up to surround the thin end of the pin and slide the opposite end of this copper cylinder over the ground pin , whereby the pin in touching the ground pin , and it further attached by the copper foil surrounding both of them. mind you , this is all inside the plastic surrounding.

would this set up be troublesome?

[sqeeek]

Brilliant. Very much planning on doing this with an annoying old Toshiba I've got.

[jeff-o]

Are the magnets getting warm because the aluminum tape is adding resistance to the charging circuit?  That might be something to worry about...

[CyberBill]

Indeed, I agree with you.

The reason they are getting warm is because the connectors are 12v and generally sucking down about 4 amps.  The magnets and aluminum, while conductive, are not as thick as the wire it replaces and have more resistance.

Even if the resistance is only .1 ohms, that is enough to make a significant amount of heat.

I'm sure by using something conductive you could lower the resistance through the magnets (or perhaps the nail) and it won't get as warm.

To the original author - great instructable, by the way :)  I would love to do something similar for a dock connector on my iPhone!

[Freeload]

I think you guys are right about the resistance, after using it for a day it was getting pretty toasty. do you think changing the aluminum tape out for Copper foil of some sort would greatly reduce this issue? Thanks again for the insights!

If the use of copper foil will solve/help the heat issue then i will hunt some down tomorrow and update the instructable.

any other thoughts on improvements/changes? 

[jeff-o]

Well, it seems to me that part of the problem is trying to push current past that adhesive layer. It isn't conductive, so you're relying on the power getting past it via the edges of the tape (where there might not be any adhesive), through any cracks or voids in the adhesive, or through the adhesive itself (though not efficiently).

You basically want to avoid confining the current to narrow pathways, like the few voids in the aluminum tape, or even the thickness of a single layer of tape.  In a high power application like this, where a few dozen up to a hundred watts are being pushed through, the conductors must be as large as you can manage.

I suggest instead of aluminum tape, use aluminum foil.  Wrap enough on for a tight fit, then slide the magnets on over top.  Further secure the assembly by covering it with heat shrink.  I'm not sure what to do on the computer side of the jack.

One more issue is the nails; over time they will corrode (perhaps faster than normal due to the current moving through them) which will also increase the resistance.  If you can, replace them with brass which won't corrode white as quickly.

[sqeeek]

http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=brass+nails#q=brass+nails&um=1&ie=UTF-8&tbo=u&tbs=shop:1&source=og&sa=N&hl=en&tab=wf&biw=1280&bih=688&fp=25a0b2344dc0e416

[gallonoffuel]

You could try applying some Deoxit Gold to the conducting surfaces. It works well for high current applications I've used it in.

[CyberBill]

I tell you what, I'm actually having a hard time visualizing how the electricity is flowing through your magnets...  Could you possibly upload a cross-section of the connectors so I can get a better idea of what is touching what?

It seems like the + (center) is just a straight-through nail... I don't think you'll have any issues there.

The - (outside) is kind of a combination of the plating on the magnets as well as the aluminum tape - correct?

Unfortunately, I think you're going to find that your dealing with resistances on the order of less than .1 ohms - and most multi-meters that I've used just don't measure that low.  This means that you're probably going to be reduced to experimentation rather than straight up measuring the resistance.

I don't think that copper foil is going to make much difference.  It is still just too thin.  I'm also not sure what the magnets are covered in (Aluminum?  Nickel?) - but it is also probably a very thin layer.

Maybe you can wrap a solid 12-gauge copper wire around the magnets and down to the foil/outer connector?

[Freeload]

First i'll just give some info:

The AC/DC adaptor stats say 19v, 1.58a, (-)-C-(+) (negative outside, positive inside, as CyberBill said)

From the magnet manufacturor:
All of our stock rare earth magnets are sintered Neodymium-Iron-Boron magnets plated in Nickel-Copper-Nickel.

Now for the adaptors:

How the magnets currently connect to the (-) outer connection of the stock plug is through multiple layers (about 6) of aluminum tape.
The (+) connection is just a common nail (I assume steel, nickel blend)

As for the internal (-) connection, the 2 washers connect to a few layers of aluminum tape, but they don't have to go through the layers to make a connection, the internal connection touches the same top layer of aluminum tape that the washers connect to.
The (+) internal connection is a copper post from a wire stud, it is coated but I don't know with what and since I cut it the copper core is exposed anyhow.

jeff-o, I hadn't thought of the adhesive in between. That is a great point. Now I'm wondering, would wrapped copper foil that has bare sides (no adhesives or coatings) have the same conductivity/resistance that a braided copper wire would have? Or is there an inevitable drop in conductivity from wrapping it? I have tracked down some thin copper foil at an art store (apparently used for embossing) that I will pick up today.

Thanks again for your suggestions and ideas

[CyberBill]

Aluminum has about 60% more resistance than copper does - so switching to copper will help so long as the thickness of the wires/foil is the same.

Steel has about 10x as much resistance as copper.  Stainless steel has 40x as much resistance as copper.  Nickel has 4x the resistance of copper.

Keep in mind that if you have a single layer of foil, whatever the resistance is, if you have another layer of foil (or strand of wire, or whatever) the same size, the resistance is now half.  Also, kind of counter-intuitively, if you have a piece of foil that is 6" long and 1" wide, the resistance will drop by half if you make it 6" long and 2" wide.

That is why I would recommend just 'beefing up' what you've got.  Coil some copper wire around the whole thing so that the wire can reduce the resistance - try to avoid running the power through the magnets themselves.

By the way, the voltage being 19v and only 1.58a is much better than if it was 12v and 4amps like I had assumed - so that is good :)  The amperage is what causes the heat, not the voltage.

[jeff-o]

The copper foil would be even better than aluminum foil. It would provide a great amount of surface area to reduce losses.  It's worth a try!

[Freeload]

I have replaced the aluminum tape with copper foil and updated the instructable. I have fully charged my laptop with the new version of the plug and heat is now a non-issue, thanks so much for the help and ideas i really appreciate it!

[jeff-o]

Wow, great work!  I'm glad we could help!

[CyberBill]

Awesome!!  I'm glad you found a solution that fixes this issue :)

[trebuchet03]

Sorry, reading that just reminded me of this

xkcd.com/643/

[computernut401]

 nice

[SRChiP]

lol

[chawla_mohali]

cool idea!!

i got dell (inspiron), 3 wire power supply! :(
Positive, Negative & Feedback (i guess)

[sqeeek]

Fixed one of those too, ignore the center pin or cut it out. It's just ground sheilding, noise canceling or something. It'll work without. Just might have to disable the 'oh crap it's messed up' warning in the BIOS

[Fieldownage]

 Positive, negative, ground perhaps?

[chawla_mohali]

hmm..
http://www.tomshardware.com/forum/9519-2-dell-laptop-power-jack-pinout
:)