Instructables

ThinkSafe: A Magnetic Power Connector for Thinkpads

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power_hole.jpg
My Thinkpad's power connection started getting flaky, so I made a magnetic connector that works just like Apple's MagSafe connectors. It's effective, cool-looking, and breaks away cleanly when kicked. I used common materials that I had around or could find at my local hardware store, so you should be able to duplicate my efforts.

These directions should work for any power connector that has the same basic design, if you make adaptations for differing sizes. See the second and third pictures in this step for a "before" portrait and a little bit of terminology.

This modification isn't destructive in any way, so it should be possible to restore your laptop to its original condition just by removing the pieces you've glued on. You can't use an unmodified power adapter once you've modded your laptop, but fortunately it's pretty easy to make the plug part, so you can make two or more spares.

Remove the battery before working on your laptop, and unplug the power cord.
 
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Step 1: Materials

Picture of Materials
In addition to what you see here, you need:
a soldering iron
epoxy
scotch tape

You will notice in most of the following instructions that I only used two magnets. This is because during my initial build, I thought that two would be sufficient, and it was only when the whole thing was built and photographed that I discovered that they were not. Rather than start over, I simply used my Dremel to insert another two magnets, and the final design you see on the first page was born.

Depending on how many materials you already have, this should cost less than $30 for the whole project.

Step 2: Plug Wrapping

The goal of this step is to get the washers fitting tightly around the barrel of the power connector. The washers will be a little loose around the barrel, so you need to cram in enough copper to get them to make a good connection with the barrel.

Cut a strip of copper sheeting and wrap it around the barrel, making it long enough that the washers will just barely slide on over it. Some trial and error will be necessary in this process. I eventually figured out that about three and a half wraps of sheeting worked best.

Step 3: Epoxy the Plug

Now that you've got the plug all washered up, it's time to bring on the magnets. Roughen the magnets and washers with sandpaper to ensure a good bond, then mix up a batch of the strongest epoxy you're comfortable with (I'm personally uncomfortable with five-minute epoxies because they set up too fast, and I like to use an epoxy that I can cut off in case I mess up).

Make sure that your magnets firmly contact both the washer and the copper foil. The magnets will be your new ground contact, so make sure that they have a good electrical connection to the ground cylinder on the original plug!

Use aluminum foil and rubber bands to make a seal so that the epoxy doesn't run off the edges. Prop the plug upright, and carefully insert epoxy in the spaces between the magnets. You don't want to get any epoxy on the top faces of the magnets, and you don't want to get any in the hole in the center. But you do want to fill the spaces between the magnets with a little pool of epoxy, bringing it almost flush with their tops.

This will seem obvious in hindsight: don't use an iron implement like a nail to apply the epoxy.

Step 4: Solder the Socket Electrode

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finished_solder.jpg
We're going to make the ground electrode be a washer on the outside of the Thinkpad, but the existing ground contact is way down in the socket. We're going to stick an electrode down in there. Again, we're using a strip of copper flashing, and we're going to solder it to a washer. The first picture is the finished product.

The strip should be slightly narrower than the ground contact inside the Thinkpad power socket, otherwise it won't have such a good connection. Do some test fittings on the laptop and bend a right angle into the strip so you know where to solder it. The strip should go all the way to the bottom of the socket. You can see that I folded over the end so that it fits more tightly.

Then, fire up your soldering iron and solder the strip to the washer. I found that the best soldering strategy is to heat the washer with the iron on one side of the strip (use a small blob of solder to increase heat conductivity), and have fresh solder ready to flow under the strip on the other side.

Step 5: Install the Socket

Now you've got your washer with its copper electrode dangling. If we were to just stick this into the laptop socket, the electrode would just kick around inside and not ever make contact. So we need something to push it against the outside. This is where the mounting tape comes in. Stick one side to the electrode, and the other side will press against the center rod in the power socket. It's double-sided tape, but only uncover one side.

This is a good time to give it a try. Gently work the electrode into the socket until the washer is flush with the surface of the laptop. If you have a multimeter, see if the washer is connected to the laptop's ground. The outer metal bits of most of the connectors on your laptop will be equivalent to ground, so check for continuity with those.

Once you're satisfied that the electrode is making contact, epoxy the washer to the face of the laptop. Make sure it's centered and even. It's not completely impossible to remove it once you've done this, but it won't be very easy .

Step 6: Cut Rod to Fit

The aluminum rod will be the contact that presses against the post in the middle of the socket on the laptop. It's tricky to get the length perfect, so you'll want to spring-load it. The spring-loaded rod sticks out further than it needs to, but then the pull of the magnets compresses the spring and the rod and magnets both make firm electrical contact.

If you have a spring that fits perfectly in the hole already, then you can skip this paragraph. I couldn't find a small enough spring, so I modified a spring from inside a pen. Snip a short segment of spring from the pen, and then use a pair of needle-nose pliers to tighten the loops. Keep tightening and fixing until the spring is small enough to comfortably fit down the hole in the plug. Don't force it -- you never know when you'll want to take it out again.

Now you want to adjust the length of your aluminum rod so that, sprung, it is slightly too long. Put the rod in the chuck of your power drill and run it against some sandpaper to wear it down quickly. Start with coarse sandpaper, and finish off with fine to ensure a nice finish. Go through a bunch of iterations to make sure it's perfect. Go through some rounds of testing -- when you attach the plug to socket, does the rod get pushed back against the spring? Do the magnets still hold them together?

Once the rod is the right length, wrap a strip of scotch tape around the part that sticks out, so that only the tip is exposed. This will help prevent you from touching the powered-up rod to the ground washer on the laptop. You can put as many layers on as you want, as long as you don't exceed the size of the hole in the laptop.

Step 7: Done!

You're done!

Well, hopefully anyway. Put the battery back in your laptop, try out your new plug, and see if you get power. You might have to fiddle with the length of the rod, or smooth out the surface of the magnet/epoxy combo. If you're not getting power, try testing the continuity between some of the washers on the plug, and the ground point on the laptop. If there's a good connection between those, then the problem must be the rod/post connection, so check on that. Make sure to clean the surfaces off so there's no grease getting in the way.

Enjoy your new freedom to trip over your power cord!
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hesdeadjim19 months ago
Another option when the side of the laptop has been broken. After fixing the standard connector several times, it was reduced a jack connector dangling out of a large hole in the side of the laptop. Online I ordered a MagSafe replacement power jack and cord for a Mac A1278. Using Volt-Ohm meter, I traced what would be power through the replacements. After removing the original cord end and jack, I soldered the replacements in place. I then used a heat-glue gun to mount the A1278 power jack in the hole in the side of the laptop. Powered it up.
FireSnake7 years ago
Great idea. i like it a great deal, but what about the magnets affective the hard-drive and other components in the laptop? Other than that, this idea can be used for other things as well...thanks
Well, I don't know if anyone reads this article anymore, but I know I did. No. Those magnets will not affect the hard-drive or any other components. The power jack is generally never directly next to the hard-drive and the magnetic field doesn't go far enough to reach it.
You'd have to pull the hard drive out and set the magnets on top of it to do any damage, mod away without fear! Magnets outside the computer are rarely a problem, unless they are very powerful and they happen to touch just the right spot.
Well, if they can manufacture HDD's with the super-duper strong magnets next to the platters, you'd probably have to put them directly on top of the platters.
do you know how HDDs work? the magnets are electromagnets and write data onto the disk. they turn on to mgnetize a spot on the disc to store a bit. if they want to demagnetize the bit, they use the other electromagnet with reverse polarity. making a spot of 1s or 0s on your disc would be bad
 You can't wreck a hard drive with magnets
They actually contain 2 very strong magnets themselves
i have seen someone total their hard drive by sticking neodyium magnets on the keyboard. they are magnetic storage devices after all. So any strong magnetic field applied in an uncontrolled manner will corrupt the information on the disk. however the magsafe link is a long way from the hard drive.
their case is shielding the inside from external magnetic forces
i tried it
Those are neodymium magnets.  Very powerful magnetic field but has a very short reach so to speak.  Once you get 5-10mm away their magnetic flux/field is at it's end.  So your hard drive is safe. 
(removed by author or community request)
Do some research Dude. Stainless steel is NOT magnetic!
Whether stainless is magnetic depends on how much chromium is included in the mix.

The more expensive grades of stainless are non magnetic due to a higher chromium content than the magnetic grades of stainless contain.
This looks good. My sister's HP PSU recently gave up the ghost so I'm looking a way at reducing the mortality rate of the upcoming replacement. I was thinking of a mag-safe breakaway cable that required no modding. I'd have to obtain a 4.7/1.7mm plug (I think we sell them where I work) and a line socket (a little harder) make up a short cable with a line socket on on end, and a mag-safe type thing on the other, to which you'd plug in the existing PSU, then with the plug, you'd add the other side of the mag-safe, and leave that sat in the laptop's socket. Two parts, easily removeable, no modding. If I ever get around to this, I'll most certainly reference you. Where's a good place for magnets? (preferably international shipping)
you can destroy your hard drive with that magnets if close enough.be careful
ummm  you cant really
take a try.you`ll belive me
eyebot1174 years ago
Clever! I would personally add the magnets to the computer instead of the cable. Then there wouldn't be any way for the magnets to harm my hard drive should the cable come near it. Despite the fact that the magnets probably won't affect the computer, stronger magnets and sensitive expensive electronics usually don't mix well.... Good coupling!
schaadrak7 years ago
Another way of doing this would be to cut the cord about three inches from the connector, then connect the wires on the cut ends of the cord to the magnets so that the magnetic leads are only attracted to their proper mates. You know, so that ground attracts to ground but repels V+. That way your not gluing stuff to your laptop and the magnets are further away from the hard drive. Not that this isn't a fantastic mod, though.
I think the magnetic break-away cable idea is a good one. It would be much easier to make. If you were really worried about reverse polarity, you could just throw in a diode bridge or rectifier on the laptop end of the cable.
A diode bridge only used for AC to DC.  The power is already DC coming from the adapter.
Think about it a little further Kegtapper, AC is composed of alternating polarities, and a diode bridge outputs a single specific polarity.  If your bridge is hooked up to provide the output you need, it doesn't matter which polarity you apply to the input.  

New inventions are often created from old things used in new ways. An inventor might say that something is usually used for a specific purpose, but shouldn't ever say that anything is used for one purpose and for one purpose only.  The Chinese used to think that gunpowder was only for fireworks.
I want an older Thinkpad so bad, but for the same price I can get a new laptop without the "nipple".
codongolev4 years ago
our deep fryer has one of these on the power cables. because it isn't really a good thing when a pot of hot oil goes all over the floor.  
static4 years ago
 Great instructable too bad it isn't  very easily applicable to my mini9 power connector. Looking forward to reading your ring magnet version.
andrestuff7 years ago
I had wanted to make a connector that when I plugged it in as I drove up to my car it would put 110 vac into the car. Then in the morning I could have a regular electric heater come on for 20 minutes or so and really warm up the inside of the car. Then rather than slipping around trying to unplug it in the cold I wanted a way that I could just "drive off" . And the unit would unplug itself. Obviously a regular power cord WOULD work but it's not very proper way to do it. This idea is pretty good if I could have made up a couple of sockets with protected 110vac holes that pins would drop into. Thanks for the help with an idea. It might still work for me.

Shop around for used kitchen appliances that use magnet to retain the power cord to srip the parts off. You would still have to hook it up, but could drive off in the morning.  I believe Anderson Power Poles have products that will make  a mechanical electrical connection, but you'll pay for those. Anyway tou could make  standard cord connection work, if you devise a way to have someting other than the electrical cord to take the strain of pulling the connector apart.

dchall85 years ago
I wish I'd seen this about $300 ago. My daughter can't seem to keep from knocking the plug out of the inside of her laptop. I can't believe it never occurred to me to look here for an answer. I never did get the magnetic plug thing until my wife brought home a Macbook from her school. Now I'm convinced. Leave it to Apple to innovate for the rest of us. This is a fantastic Instructable. Could you just clarify how many magnets to use ;-) -seriously though, the ring magnet is the way to fly. Great job!
static dchall84 years ago
As it often soes Apple copied another idea that has been in existance, not that I'm saying apple hsn't had any original ideas. My inexpensive Dollar Store deep frier uses magnets retain the power cord.
it says 4 if you scroll over the magnest in the second picture
zachninme7 years ago
I am actually working on a USB version, not to be "breakaway", but to be unisex, so that a male = female connector. Coming along well-ish.
You should look at the construction of the Anderson "powerpole" connectors, and the old IBM Token Ring genderless connectors, for design ideas. Also the old General Radio coax connector, and the APC-7 instrumentation connector. Just curious, what do you intend to do with a genderless USB connector, aside from accidentally connecting two hosts together and watching their power logic fight and/or fry? Is On-the-Go common enough to justify this?
I have just so many different USB cables hanging around, and I can never match A to B... so to speak. I am smart enough to not do stupid things... Oh, and after reading my post, I forgot to say why I posted it here. I was planning on using magnets, and this instructable was inspirational.
And actually, I just figured it out awhile ago, sorta. Not exactly what I had in mind, but awesome none-the less :-) Instructable coming soon!
Has anyone consider the low current rating of the USB connectors? If I remember correctly the Acers use 19v @ 3.4A  And USB connectors are rated considerably lower. Most of the USB devices don't even carry 1A.  

Watch your power rating, or you will have a melted plug stuck to the side, or worse yet, a short that cannot be pulled out.  Yes I am a 'Laptop Doctor'
I want to make the same thing, magnetic USB connector. Where can I read the instructions? Can you solder any wire to the surface of the NIB magnets? Do you have to wrap the magnets with some kind of copper or tin strips? Thanks for sharing.
PKM tinyrose6 years ago
You can probably solder any common type of wire to the magnets, with a few gotchas to watch out for. Firstly, aluminium is not great for soldering to because it is covered with a layer of very hard oxide which stops the solder "wetting" it properly- you have to sand aluminium quite hard if you want to solder to it. Copper tends not to have this problem, iron/steel might and stainless steel will probably also need sanding. Secondly, soldering to magnets is not a great idea because magnets don't like heat. Excessive heat makes magnets lose some or all of their magnetism (depending how hot you get them for how long), so soldering to magnets is usually discouraged. You are probably better off letting them stick themselves to a piece of steel, adding epoxy around the sides to keep them in place, and then soldering the steel connection to your wires to keep the heat away from the magnets. This instructable uses epoxy and contact fittings to avoid soldering near the magnets at all, and that is probably the best solution if you can do it.
NormMonkey7 years ago
This is great! I wonder if anybody has tried it with poured resin instead of epoxy, maybe enclosing the group of washers as well so that only the magnet surfaces are exposed? You could pour too much and dremel / sand down to expose the magnets after. Stick a bit of tightly rolled paper topped with clay in the tube part to keep resin out of there.
Epoxy is a type of resin.  Most epoxy resins are liquid and can be poured.  5min epoxy is the exception, not the norm.  You might be thinking of polyester or vinylester resins.  I am building a Cozy MKIV which is epoxy/fiberglass/foam composite.  Most epoxy you see in hardware stores is the 5min variety, mostly because it's pretty expensive compared to polyester resin, and most varieties of epoxy use pretty nasty chemicals for the hardener.  Brain damage, skin reactions, etc.  As always follow the safety instructions on the packaging!
NormMonkey7 years ago
Last but not least: the power plug from the adapter had that recessed post-receptacle for a reason: they don't want to shock users with 16VDC. This mod bypasses that safety factor. The MagSafe has 16.5VDC on its pins too but the middle one keeps the plug from being energized unless it's connected to the laptop. This one will be energized full-time. I'd guess 16VDC isn't enough to hurt if accidentally touched with fingers, but if you have kids I'd think twice about this. I don't have kids so it's a-modding I will go! Thanks for a great idea! I can see this being useful for all kinds of power sockets, too. Another idea: they make ring-shaped rare-earth magnets *grin*
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