“Destroying Myths” - this section is dedicated to the most common myths that have taken root in the world information technologies. The editors of the CHIP test laboratory will help you distinguish fiction from the truth.

Many people believe that if an ordinary magnet ends up near a computer or hard drive, this will result in data loss.

Is it true.

This opinion spread when 5.25- and 3.5-inch floppy disks were widely used. The magnets really shouldn’t have been brought too close to these data carriers: even a distance of three centimeters was enough to destroy all the data. However, even neodymium magnets with a powerful magnetic field do not pose any danger to hard drives. Modern hard drives with a capacity of 1 TB or more consist of two to four plates coated with a magnetic layer based on iron oxide and cobalt. Information on the platters is located in small areas (domains) of the disk, which can have two states of magnetization - 0 or 1. Bits of information on modern HDDs are stored in vertical domains. This method, called perpendicular recording, allows you to store up to 19 GB of information on one square centimeter.

Magnetic fields Reading and writing data to the HDD is carried out by moving the head above the platter at a distance of only 10 nm. This element works as an electromagnet and creates a strong field, under the influence of which domains are magnetized.

Thus, it is magnetic fields that allow information to be written or erased in domains.

But why then does an ordinary magnet pose no danger? The fact is that the plates are so strongly magnetized that only very powerful fields with an induction of over 0.5 Tesla can negatively affect the operation of the HDD. Since the strength of the magnetic field decreases with distance from the object, already at a distance of a few millimeters it will drop to a negligible value. Therefore, magnets brought to the HDD are too weak to affect the information stored on the hard drive.

Even a neodymium magnet with an adhesive force of 200 kg at a distance of 10 mm from an object creates a field with a magnetic induction of only 0.3 Tesla. However, be aware that if a magnet is placed near a running hard drive, it may tilt the read/write head to the side or cause it to touch the platter. This is fraught with recording errors and, as a result, data loss.

To date, probably only the deaf have not heard about neodymium magnets. They are made from an alloy - NdFeB, which has remarkable magnetic properties (it is not only powerfully magnetite, but also very resistant to demagnetization). It is not difficult to buy neodymium magnets in Moscow, but they can bring a lot of benefits in the household. Let's consider several non-trivial ways to use such magnets in the household. So,

The simplest and most fun are toys and puzzles. For this, rather weak small magnets are used, usually in the form of balls. Various complex shapes and sculptures are assembled from them. But do not forget that such magnets should NEVER be given to children under 4 years of age! A swallowed pair of such magnets, pinching the wall of the intestines or stomach, can easily cause its perforation with all the consequences.

Neodymium magnets are excellently used as clamps. In principle, a pair of medium magnets is quite capable of replacing a bench vise. However, it is more convenient to use magnets, since they can be used to fix parts of complex shapes.

Motorists will probably be interested in using neodymium magnets as an oil filter. If you hang it on the engine crankcase drain plug, it will trap all metal inclusions in this place, which will then be easy to remove.

Due to their strength, such magnets can be successfully used in search activities. For example, find a fallen needle in a carpet, or a machine gun from the Great Patriotic War in a river (special search magnets with an eye for a rope are sold for this). Can also be used to search for reinforcement in walls.

Magnets have been used by magicians for a long time to create the illusion of levitation. With the advent of neodymium, such tricks reached a new level.

You can also successfully magnetize various steel objects (screwdrivers, bits, tweezers, needles, etc.) with such a magnet. They can even re-magnetize a demagnetized ordinary magnet.

Fixing inventory and tools. Special holders with magnetic properties will help you in proper planning of your workspace.

Dent repair, from body repair to wind instrument repair.
To delete data from magnetic media (hard drives, audio and video cassettes, credit cards). A powerful magnetic field perfectly removes all information. Quickly and without additional effort.

In general, neodymium magnets are simply an indispensable assistant in the household. Only when working with them, especially powerful ones, strictly follow safety precautions. If a finger or other part of the body gets caught between magnetic objects (I already wrote about children), this could end very badly.

Take care of yourself!
Based on materials from: http://neo-magnets.ru/

Not everything is in the photo! Only those that I "sentenced" when I conceived this homemade !

Some are out of order. Others are simply outdated. (By the way, there is a general trend of declining quality: modern hard disks fail quite often. The old ones, one or two gigabytes (or even much less), are all working!!! But they can no longer be used - they have a very low speed of reading information... And they have very little memory. So it's not worth it.

But you can’t even raise your hand to throw it away! And I often wondered what could be made from them, or how to use them...

On the Internet, at the request “...from the hard drive” there are mainly “super-talented” ideas for creating a sharpener!!! People with a serious look show how to trim the case and cover the disc itself. sandpaper, and make a super mega-cool sharpener, powering it from a computer power supply and using your own hard drive motor!

I haven’t tried it... But I think it will be possible to sharpen with such a sharpener... well, maybe nails!... And even then, if you don’t press too hard!!

And now, when I was doing this, I remembered that hard drives have powerful neodymium magnets. And since during welding work “there can never be too many angles,” then, upon completion of the last homemade project, I immediately disassembled one of hard drives to see what you can operate with)))

The magnet (I pointed to it with a red arrow) is glued to a metal bracket, which, in turn, is secured with a screw.

Old hard drives had one or more massive magnet. There are two of them in the new ones. The second one is below:

This is what I got when I disassembled my disks:

By the way, the discs themselves also interested me. If anyone has ideas for using them, please share them in the comments...

To begin with, I decided to search the Internet to see if anyone had already invented this method of making welding angles?!)))
It turned out yes! We've already made these devices from hard drives! But there the man simply placed a wooden board between the metal plates, to which he screwed magnets. I immediately rejected this method for several reasons:

Firstly, the combination of “arc welding + wood” is not very good!

Secondly, at the ends of these squares a rather complex shape is obtained. And it will be very difficult to clean them! And he will take on a lot. Let me give you an example of a photo from my last publication. They have a weak magnet on them, and this one, after lying on the workbench where they worked with metal:

And thirdly, I didn’t like that the square had very wide ends. That is, when welding some structures whose components are narrower than itself, it cannot be used.

Therefore, I decided to go a different route. Make, like the “wooden” one, not the template plates of the case, but the end itself between them, but make this end smooth and closed.

In a previous publication, I already wrote that all magnets have poles, which, as a rule, for permanent magnets are located on wide planes. "Short" these poles magnetic material not desirable, so this time I decided to make the side plates of the case from a non-magnetic material, and the end plate from a magnetic one! That is, “exactly the opposite”)))

So what I needed:

1. Neodymium magnets from old computer hard drives.
2. Non-magnetic stainless steel plate (for the housing).
3. Thin magnetic steel.
4. Blind rivets.

First of all, I started making the case. I had this piece of stainless steel sheet. (I don’t know the brand, but steel does not stick to a magnet).

Using a plumber's square, I measured and cut out two right triangles with a grinder:

I also cut the corners of them (I forgot to take a photo of this process). Why cut the corners, I already said - so as not to interfere with welding work.

I made the precise adjustment of the corners manually on a piece of emery cloth spread along the plane of a wide profile pipe:

Periodically, I put the workpieces into the square and looked “through the light.” After the corners were out, I drilled holes for the rivets, connected the plates through them with M5 screws, and checked the corners again! (The requirements for accuracy here are very high, and when drilling holes, I could make an error).

Next, I started making the magnetic plate itself, which, as I already said, I want to place at the end of my square. I decided to make the thickness of the square 20 mm. Considering that the side plates are 2 mm thick, the end plate should be 16 mm wide.
To make it, I needed thin metal with good magnetic properties. I found it in the case of a faulty computer power supply:

Having straightened it, I cut out a strip 16 millimeters wide:

This is where the magnets will be placed. But here one problem arose: the magnets, having a curved shape, do not fit into the width of my plate....

(A little about the magnets themselves. Unlike acoustic speakers, hard drives use not ferrite, but so-called neodymium magnets. They have a significantly higher magnetic force. But, at the same time, they are more fragile - even though they are They look like solid metal, they are made of sintered rare earth metal powder. And they break very easily. In a hard drive, they are glued to a steel chassis, which, in turn, is already screwed on.)

I did not peel off the magnets from the steel plates - I only need one working plane from them. I simply cut off the protruding plates with a grinder, and a little of the magnets themselves.

In this case, a regular abrasive wheel (on steel) is used. Rare earth metals have the property of spontaneously igniting in air in a highly crushed state. Therefore, do not be alarmed - the “fireworks” of sparks will be much stronger than expected.

I remind you!!!
Permanent magnets are afraid of strong heat!! And especially - sudden heating! Therefore, when cutting, they MUST be cooled!
I simply placed a container of water next to it, and periodically lowered the magnet into the water after making a small cut.
So, the magnets are cut off. Now they fit on the strip.

Inserting long M5 screws into the holes for the rivets and securing them with nuts, I bent the following complex structure around the perimeter of the template plate:

It is on this that the magnets will be located inside.

Users are often wary of magnets lying near electronics. Someone told us, or we saw it ourselves: these things can easily distort the image, or even permanently break expensive gadgets. But is the threat really that great?

Imagine the situation: magnets were bought as a gift for a child. Less than an hour later, these things end up near the computer, near the smartphone, near the TV... Dad’s many months of salary are at risk. The father of the family selects the “magnets” and throws them on the far shelf, but then thinks: maybe it’s not so scary?

This is exactly what happened to DigitalTrends journalist Simon Hill. To find the truth, he decided to turn to experts.

Matt Newby, first4magnets:

“People have such ideas left over from the old electronic devices- for example, CRT monitors and televisions, which were sensitive to magnetic fields. If you placed a strong magnet near one of these devices, you could distort the image. Fortunately, modern televisions and monitors are not that sensitive.”

What about smartphones?

“The vast majority of magnets you encounter every day, even some very strong ones, will not have a negative effect on your smartphone. In fact, there are also several very small magnets inside it that are responsible for important functions. For example, wireless magnetic induction charging is used.”

But it’s too early to relax. Matt warns that magnetic fields can still cause interference with some sensors, such as the digital compass and magnetometer. And if you bring a strong magnet to your smartphone, the steel components will be magnetized. They will become weak magnets and will not allow the compass to be calibrated correctly.

Don't use a compass and think it doesn't concern you? The problem is that others need him, sometimes very much. required applications. For example, Google Maps a compass is required to determine the orientation of the smartphone in space. It is also necessary in dynamic games. Owners of the latter iPhone models magnets can even interfere with taking photographs - after all, a smartphone uses optical stabilization Images. Therefore, Apple does not recommend that manufacturers of official cases include magnets or metal components in their products.

Next up are hard drives

The idea that magnets easily destroy the contents of HDDs is still very popular today. Suffice it to recall an episode from the cult TV series Breaking Bad, where the main character Walter White uses a huge electromagnet to destroy digital incriminating evidence on himself. Matt takes the floor again:

“Magnetically recorded data can be damaged by magnets—this includes things like tapes, floppy disks, VHS tapes, and plastic cards.”

And yet, is it possible that what Bryan Cranston’s character did could happen in real life?

“Theoretically, damage to a hard drive by an incredibly strong magnet if you bring it directly to the surface of the drive is possible. But hard drives contain neodymium magnets...a regular sized magnet won't hurt them. If you, for example, attach magnets to the outside system unit your PC, no effect on HDD it won’t have any effect.”

And if your laptop or PC runs on solid state drive, there is nothing to worry about at all:

“Flash drives and SSDs are unaffected by even strong static magnetic fields.”

At home we are surrounded by magnets, says the expert. They are used in every computer, speaker, TV, motor, smartphone. Modern life without them would simply be impossible.

Perhaps the main danger posed by strong neodymium magnets is the danger of being swallowed by a small child. If you swallow several at once, they will be attracted to each other through the intestinal walls, Matt warns. Accordingly, the child cannot avoid peritonitis (inflammation of the abdominal cavity - editor's note), and, therefore, immediate surgical intervention.