Busting Myths - This section is dedicated to the most common myths that have taken root in the world of information technology. CHIP Test Lab editors will help you distinguish fiction from truth.

Many people believe that if an ordinary magnet gets close to a computer or hard drive, it will lead to data loss.

True.

This opinion spread when 5.25 and 3.5 inch floppy disks were widely used. Magnets really shouldn't have been brought closer 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 pose no danger to hard drives. Modern hard drives with a volume 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 over the plate at a distance of only 10 nm. This element works as an electromagnet and creates a strong field, under the influence of which the domains are magnetized.

Thus, it is magnetic fields that make it possible to write or erase information 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 more than 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 several millimeters, it will fall to a negligible value. Therefore, the magnets brought to the HDD are too weak to affect the information stored on the hard disk.

Even a neodymium magnet with an adhesion force of 200 kg at a distance of 10 mm from the object creates a field with a magnetic induction equal to only 0.3 Tesla. However, it should be understood that if a magnet is brought up to a working hard drive, it can tilt the read / write head to the side or cause it to touch the platter. This is fraught with write errors and, as a result, data loss.

Often, users are 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 big?

Imagine a situation: magnets were bought for a child. In less than an hour, these gizmos are near the computer, near the smartphone, near the TV ... Dad's many months' salary is under threat. The father of the family takes the "magnets" and throws them on the far shelf, but then he thinks: maybe not everything is so scary?

This is exactly what happened to DigitalTrends journalist Simon Hill. In search of the truth, he decided to turn to experts.

Matt Newby, first4magnets:

“People have such ideas from old electronic devices - for example, CRT monitors and televisions, which were sensitive to magnetic fields. Placing a strong magnet near one of these devices could distort the image. Fortunately, today's TVs and monitors are not that sensitive. "

What about smartphones?

“The vast majority of the magnets you encounter every day, even some of the very strong ones, will not negatively impact 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 interfere with some sensors, such as the digital compass and magnetometer. And if you bring a strong magnet to your smartphone, the steel components will magnetize. They will become weak magnets and prevent the compass from being properly calibrated.

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

Next in line are hard drives

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

"Magnetically recorded data can be damaged by magnets - this includes things like cassettes, floppy disks, VHS videotapes and plastic cards."

And yet - is it possible what Brian Cranston's character did in real life?

“In theory, damaging a hard drive is an incredibly strong magnet, if you bring it right up to the surface of the drive, it's possible. But the hard drives contain neodymium magnets ... a normal size magnet won't hurt. If you, for example, attach magnets to the outside of your PC's system unit, this will have no effect on the hard drive. "

And if your laptop or PC is running on an SSD, there is nothing to worry about:

"Flash drives and SSDs are not affected even by 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 would be simply impossible without them.

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

In the photo - not all! Only those that I "sentenced" when I conceived this homemade product!

Some are out of order. Others are simply outdated. (By the way, there is a general tendency for quality to decrease: modern hard drives fail quite often. Old ones, by one or two gigabytes (or even much less), are all in good order !!! But they can no longer be used - they have very little speed of reading information ... And there is very little memory in them, so it's not worth it.

But to throw it away - the hand does not rise! And I often wondered what could be made of them, or how to use them ...

On the web, on the request "... from the hard drive", there are mainly "super-talented" ideas for creating a sharpener !!! People with a serious look show how to cut the case, glue the disc itself with sandpaper, and make a super-mega-sharp sharpener, powered by a computer power supply, and using your own hard drive motor!

I have not tried it ... But I think it will be possible to sharpen on such a sharpener ..... well, perhaps, nails! .... And even then, if you don't press hard !!

And now, when I was doing, I remembered that hard drives have powerful neodymium magnets. And since when welding "there are never too many squares", then, upon completion of the last homemade product, I immediately disassembled one of the hard drives to see what it was possible to operate with)))

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

In old hard drives, the magnet was one or more massive. The new ones have two of them. The second is at the bottom:

Here's what I got by reassembling my disks:

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

To begin with, I decided to search the net, has anyone already invented this method of making welding corners ?!)))
It turned out yes! We have already made these adaptations from hard drives! But there the man simply placed a wooden board between the metal plates, to which he screwed magnets with screws. I immediately rejected this method for several reasons:

First, the arc + wood combination is not very good!

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

And thirdly, I didn't like the fact that the square is obtained with very wide ends. That is, when welding some structures, the components of which are narrower than himself, he cannot be used.

Therefore, I decided to go the other way. Make, as in the case of a "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, are located on wide planes in permanent magnets. It is not desirable to "close" these poles with a magnetic material, so this time I decided to make the side plates of the case from non-magnetic material, and the end plate from magnetic! That is, "exactly the opposite")))

So what I needed:

1. Neodymium magnets from old computer hard drives.
2. Plate made of "non-magnetic" stainless steel (for the case).
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 doesn’t stick to the magnet).

Using a plumbing square, I measured and cut out two right-angled triangles with a grinder:

I also cut the corners in them (I forgot to photograph this process). Why cut corners, I have already said - so as not to interfere with welding.

I did the exact adjustment of the corners manually on a piece of emery cloth, spread along the plane of a wide profile pipe:

From time to time I put the blanks in the square and looked "at the light". After the corners were taken out, I drilled holes for rivets, connected the plates through them with M5 screws, and checked the corners again! (The requirements for accuracy are very high here, but, when drilling holes, I could admit an error).

Then I proceeded to make the magnetic plate itself, which, as I 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 a thin metal with good magnetic properties. I found it in the case from a faulty computer power supply:

Straightening it, I cut out a strip, 16 millimeters wide:

This is where the magnets will be placed. But then 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 magnets, but so-called neodymium magnets. They have a much higher magnetic force. But, at the same time, they are more fragile - although they are They look like all-metal, they are made of sintered powder of rare earth metals. And they break very easily. In the hard drive, they are glued to a steel chassis, which is already screwed on.)

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

This uses a conventional abrasive wheel (for steel). Rare earth metals tend to spontaneously ignite 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 - a sharp heating! Therefore, when cutting, they ALWAYS need to be cooled!
I just put a container of water next to it, and periodically dipped the magnet into the water after making a small incision.
So the magnets are cut. They are now placed on the strip.

Having inserted long M5 screws into the rivet holes, and fastened them with nuts, I bent such a complex structure around the perimeter of the template plate:

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