Previous in Forum: Does electricity have a weight/mass?   Next in Forum: lux calculation
Close
Close
Close
17 comments
Rate Comments: Nested
Associate

Join Date: Feb 2008
Location: New York
Posts: 54
Good Answers: 2

Magnets vs. Laptop

05/16/2008 7:52 PM

I want to build a magnetic coupling for my laptops power supply plug (a la mac), but I'm hesistant to bring rare earth around my hard drive et al.

Is there a spec or standard I can look for detailing acceptable fields to expose this junk to?

Thanks.

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Guru
New Zealand - Member - Interested in everything- see my Profile please APIX Pilot Plant Design Project - Member - Member Engineering Fields - Electrical Engineering - Member Engineering Fields - Power Engineering - Member Engineering Fields - Civil Engineering - Member Hobbies - Musician - Autoharp and Harmonica Hobbies - Hunting - Member Hobbies - Fishing - Member

Join Date: Nov 2007
Location: Christchurch, (The Garden City), South Island, New Zealand
Posts: 4395
Good Answers: 230
#1

Re: Magnets vs. Laptop

05/16/2008 9:20 PM

Hello Dead Bear

Why do you need a "Magnetic Coupling" for your laptop?

Has the socket in the laptop failed, or the contacts become loose?

Advise further with

Kind Regards....

__________________
"The number of inventions increases faster than the need for them at the time" - SparkY
Register to Reply
Associate

Join Date: Feb 2008
Location: New York
Posts: 54
Good Answers: 2
#2
In reply to #1

Re: Magnets vs. Laptop

05/16/2008 11:12 PM

While it still works now, the jack has loosened significantly.

I hope to pre-empt having to prop the cord in place....... or I could just wait until that day. But regardless, my suspicious ignorance stands in the way.

Thanks.

Register to Reply
Guru
New Zealand - Member - Interested in everything- see my Profile please APIX Pilot Plant Design Project - Member - Member Engineering Fields - Electrical Engineering - Member Engineering Fields - Power Engineering - Member Engineering Fields - Civil Engineering - Member Hobbies - Musician - Autoharp and Harmonica Hobbies - Hunting - Member Hobbies - Fishing - Member

Join Date: Nov 2007
Location: Christchurch, (The Garden City), South Island, New Zealand
Posts: 4395
Good Answers: 230
#3
In reply to #2

Re: Magnets vs. Laptop

05/17/2008 3:49 AM

Hello again, Dead Bear

Most Plug/socket combinations have metal "leaves or similar, acting like springs', which ensure reasonably tight connections.

Check whether it is a set of weak metal "leaves/springs" in the cord plug (most likely), where that plugs into the laptop, or the moulded plug in the laptop.

It is probable that the laptop pins are OK, and thus a few Dollars will get you a replacement power cord, and that should last for another few years, at which time, you need to repeat the replacement.

Advise further, with

Kind Regards....

__________________
"The number of inventions increases faster than the need for them at the time" - SparkY
Register to Reply
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16512
Good Answers: 670
#4

Re: Magnets vs. Laptop

05/17/2008 5:15 AM

This is just a 'bad idea'.

The usual problems are.
1. is the solder joint between connector and motherboard.
2. Failure of the cable near the strain relief at one or other cable end.
3. Bending of spring blade contact in socket.

The soluitions are...reflow solder, replace connector/cable/psu, re-tension spring respectively.
Adding a buch of magnets won't actually solve any of the above problems.
Although it may be fun...which in itself is a worthy objective.

Del

__________________
health warning: These posts may contain traces of nut.
Register to Reply Score 1 for Good Answer
Guru
New Zealand - Member - Interested in everything- see my Profile please APIX Pilot Plant Design Project - Member - Member Engineering Fields - Electrical Engineering - Member Engineering Fields - Power Engineering - Member Engineering Fields - Civil Engineering - Member Hobbies - Musician - Autoharp and Harmonica Hobbies - Hunting - Member Hobbies - Fishing - Member

Join Date: Nov 2007
Location: Christchurch, (The Garden City), South Island, New Zealand
Posts: 4395
Good Answers: 230
#5

Re: Magnets vs. Laptop

05/17/2008 5:20 AM

Hello again, Dead Bear

I should have pointed out earlier, that if any actual connection is loose, there is risk of an electrical arc, which may either destroy the laptop, cause electrical shock, or cause a fire.

Del the cat has pointed out further possible causes, in his post above, any or all of which may be the cause of electrical arcing.

Best to get the problem sorted out, while you are still in one piece.

Kind Regards....

__________________
"The number of inventions increases faster than the need for them at the time" - SparkY
Register to Reply
Associate

Join Date: Feb 2008
Location: New York
Posts: 54
Good Answers: 2
#6
In reply to #5

Re: Magnets vs. Laptop

05/17/2008 8:42 PM

Thanks for your advice.

Register to Reply
Power-User

Join Date: Nov 2007
Location: South Florida
Posts: 394
Good Answers: 8
#7
In reply to #6

Re: Magnets vs. Laptop

05/18/2008 12:04 AM

Hi, Dead_Bear

Magnets will give you the most bizarre results - if you must, try velcro or even duct tape. Won't look to great but it's worked for me in the past. Even so, you don't want the converter brick that close to the system.

Please advise: what is the make and model number of the laptop?

Are you into "The Dead"? You're a published musician - nice!

Later, buddy,

Orpheuse

__________________
Orpheuse
Register to Reply
Guru

Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
Posts: 6215
Good Answers: 248
#8

Re: Magnets vs. Laptop

05/18/2008 12:51 AM

I have to disagree with the others on this one! The MagSafe™ power connector is my absolute favorite improvement of the MacBook Pro (on which I'm typing) over previous Mac laptops. (If I remember correctly, this is my 7th). I lost a Titanium PowerBook when I tripped on the power cord getting up from my desk, knocking it off the desk. The screen was smashed when it hit the arm of my chair, and at that time replacement screens were so expensive that I elected to upgrade instead.

I knocked the following Aluminum Powerbook off the desk at least twice in a similar fashion, but fortunately did not break the screen.

I also have multiple times gotten up and started to walk away, forgetting the the power cord was still plugged in. At least one of those times it pulled the computer out of my hands.

I have repaired dozens of laptop power connectors (both Mac and non-) that came unsoldered from the circuit board due to such strains.

I've had the MacBook pro about a year now, and the MagSafe™ connector has performed flawlessly, saving me from minor to possibly major accidents at least a dozen times.

Now back to the original question. The magnet is in the left rear corner of the computer, and the Hard drive is in the left front corner; it is about 4 inches from the magnet to the hard drive. I can't be sure about the exact configuration of the magnet, but it surrounds the connector, and a small screwdriver is most strongly attracted to the four corners, with a clearly stronger attraction to the top corners. A Ø 3/16" by 3/16" long rare earth magnet insists on moving to the top corners, indicating that the North Pole is on the rear and the South pole is toward the front. It thus appears to be essentially a 'U' magnet with the poles facing outward, so very little of its field will be directed inside the computer.

The connector on the power supply cord has a heavy (0.055" wall top and bottom, 0.080" wall on sides, apparently about 0.2" deep) attractor ring surrounding the five pins. The center pin is a sense pin; the outer pins are positive and the inner pair are the negatives, so the plug can be inserted either way. The pins are spring loaded and gold plated. The tips on the computer have concave ends, and those on the cable are convex, but they do not slide one inside the other.

I admire your desire to provide that protection for your computer, but I've never seen a rare earth 'U' magnet. It may well be a cylindrical magnet with an appropriately shapedpair of pole pieces. Good luck!

Dick

__________________
Teaching is a great experience, but there is no better teacher than experience.
Register to Reply
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16512
Good Answers: 670
#9
In reply to #8

Re: Magnets vs. Laptop

05/18/2008 4:35 AM

You are not dissagreeing...!

We never said the MagSafe connector is bad...

Merely that trying to make a do it yourself one is a bit daft.

Del

__________________
health warning: These posts may contain traces of nut.
Register to Reply
Associate

Join Date: Feb 2008
Location: New York
Posts: 54
Good Answers: 2
#15
In reply to #8

Re: Magnets vs. Laptop

05/18/2008 9:36 PM

My kind regards for the details. I was mainly concerned, because the ring magnets I wanted to use (as they cleanly fit around the male adaptor) "shot" their fields directly into the machine. It makes sense that Mac would use a horseshoe to avoid this.

You description accents the main advantage of the MagSafe: that it can make a clean break subjected to a 90 degree shock. This was discussed earlier and wouldn't be solved by simply glueing to ring magnets in place.

I think a junction further down the power cord is the answer, and if the jack breaks, I can just resolder it or hardwire a cord out to marry the power cable. (Depending on the state of my warranty when it does break)

Thanks everyone for your advice.

EDIT: and here is the original site that gave me the idea:

http://www.instructables.com/id/ThinkSafe:-A-Magnetic-Power-Connector-for-Thinkpad/

I have a thinkpad................

Register to Reply
Guru

Join Date: Jul 2006
Location: Silicon Valley
Posts: 5356
Good Answers: 50
#10

Re: Magnets vs. Laptop

05/18/2008 5:08 AM

I have friend who have never experienced this problem. I think it's time to go back to Apple and get it fixed properly.

__________________
"Perplexity is the beginning of dementia" - Professor Coriolus
Register to Reply
Guru

Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
Posts: 6215
Good Answers: 248
#11
In reply to #10

Re: Magnets vs. Laptop

05/18/2008 9:58 AM

Hello Vermin

You misread the OP! He or she want's to add Apple's kind of safety release to some other brand of computer.

__________________
Teaching is a great experience, but there is no better teacher than experience.
Register to Reply
Guru

Join Date: Jun 2006
Posts: 501
Good Answers: 8
#12

Re: Magnets vs. Laptop

05/18/2008 11:15 AM

There is an awful powerful magnet built into your hard drive already.

The magnet connection should not give you a problem.

If you use CRT, still have floppy's in use then you would have to be careful where you put the magnet.

However as asked the answer is a qualified no.

Register to Reply
Associate

Join Date: Aug 2006
Location: Phoenix Arizona
Posts: 44
Good Answers: 13
#13

Re: Magnets vs. Laptop

05/18/2008 7:38 PM

It would be possible to attach the magnet to the cord itself and a small steel plate to the laptop. The lines of flux would flow through the plate (If using horse shoe magnets) and would not reach inside the laptop. As for using rare earth magnets seems a little over kill unless your suspending the laptop by the cord. (Which might be the root of your problem.) Still it is best to fix it properly. Most power supply problems I have found as described were with the contacts in the computer being bent and breaking the plastic shell of the receptacle. This is usually only noticable when the plug is placed into the receptacle.

Good Luck

__________________
"If you need a machine and don't buy it, then you will ultimately find you have paid for it but don't have it" - Henry Ford. (Also my excuse when adding to my ever expanding collection of tools)
Register to Reply
Power-User

Join Date: Mar 2008
Location: London England
Posts: 288
Good Answers: 3
#14

Re: Magnets vs. Laptop

05/18/2008 9:23 PM

Hello Dead Bear,

just a thought....................can you not google for the design layout of the MAC and the Computer you wish to use the Magnetic joint on?

You may find the MAC has a protective shield around the HHD? I don't know because I have never seen a MAC internals.

Actually, I thought the new MACs did not use Hard drives but solid state instead. That could perhaps make it easier for the designers to place a magnet in the body of the machine because the solid state takes less space, or, if a rare earth magnet, it could be on the outside with perhaps a shield entirely outside, thus eliminating any worry about flux drift?

Whatever, good luck! Do tou have an old machine you can do a 'dry run' on first?

As you may have guessed I am not an expert, but, am just thinking things through.

jfmfit

Register to Reply
Guru

Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
Posts: 6215
Good Answers: 248
#16
In reply to #14

Re: Magnets vs. Laptop

05/19/2008 1:21 AM

No, there is no protective shield around the HDD in the Mac. And yes, it IS a HDD (2.5" SATA in the MacBook Pro). In the MacBook Air, they went to a 1.8" HDD, currently 80GB, with a 64G Flash memory unit available as an upgrade. I haven't had an opportunity to see one of those upgrades yet, nor talked to anyone who has used one, but I assume it should use less power than the HDD and make the battery last somewhat longer.

The magnet is inside the case, and its strength indicates that it must be a rare earth type.

BTW, Apple has used rare earth magnets other places in laptops for many years: The latches on most use a magnet to pull the latch hooks out of the screen assembly, while on the MacBook, the only latch is a magnet. The keyboards are commonly held down by magnets; a magnet actuates a Hall effect sensor to tell the computer when the screen is closed, and of course there are the loudspeakers and the magnets that help spin the HDD and move its head around.

__________________
Teaching is a great experience, but there is no better teacher than experience.
Register to Reply
Power-User

Join Date: Mar 2008
Location: London England
Posts: 288
Good Answers: 3
#17
In reply to #16

Re: Magnets vs. Laptop

05/19/2008 2:23 AM

Hello dkwarner,

thanks for the info, theres certainly a lot to take in!

I had a PC (not a mac) laptop. I put the lead in to charge it and had a seizure. The laptop slid off my lap and, because there was a plug in there otherwise hidden socket, it pushed the motherboard in and cracked it. It was another four years before I was able to save up enough to build my own. Using all the components chosen by me. It was just as I wanted. Needs a bit of TLC now though. I have had it since 2004. Now you can get the same spec for just a couple of hundred pounds, it cost me a lot more than that. But I would be lost without it.

My family and friends and have more up to date models than mine, but do nothing to keep them up to date. I know that only one has any security software on it that is actually used. I am not saying I am an expert on computing, far from it. In fact I only have a computer. No scanner or printer but, I was trying to help them by advising them to download a freeware software security but they were pretty rude and told me to mind my own business. I do not email them at all now, simply because I have no idea how safe their computers are and I have had two nasty infections in my first laptop and, I don't want another!

I was under the impression the new model Macs did not have hdd. I know it was wrong now. I suppose, thinking about it..................if I had the magnetic connection I may not have smashed my Motherboard? I did not there was such a thing anyway!

I have thought and continue to think it may pay me to go for a mac when and if I upgrade. They don't seem to have nearly so much trouble from attacks as windows does.

I was always told that a MAC is not a PC. But there boundaries have blurred a bit since I first went for a computer in 1999.

hey, thanks for emailing me. Take care...........

jfmfit

Register to Reply
Register to Reply 17 comments

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

avi-tech (1); Dead Bear (3); dkwarner (3); jfmfit (2); jmart23 (1); Orpheuse (1); Sparkstation (3); user-deleted-1105 (2); vermin (1)

Previous in Forum: Does electricity have a weight/mass?   Next in Forum: lux calculation

Advertisement