Demagnetizing CDs?! (more Techmoan fun)

[simbloke]

Yes, Techmoan reviews a device to demagnetize CDs, with predictable results. Matt must be a lurker here surely?

 

[Joachim Herbert]

I actually got a really large and heavy demagnetizing coil for repair of TV display tubes. It comes at a white about 800 and if you put a CD on it it there sometimes is a slight rattle or movement of the CD. This seems to show some interaction between the magnetiser and CD.

I did use that in former times to erase tapes, which is not as easy as you might think, but this device did the job.

When I started to rip my collection, every now and then CDs produced inconsistent results; they did not rip correctly. Looking back about thirty to forty percent of these did work after being processed with the demagntizer.

I never put this to a scientific test; I was just happy, that it may this CDs work.

But to repeat this: The device I used is completly different from device tested in the video. And I have absolutely no idea what was going on there.

 

[Tillerr]

Interesting. What are the possibilities of a demagnetized disk?

 

[HarmonicTHD]

Interesting. What are the possibilities of a demagnetized disk?

I am not sure, so just in case to avoid misunderstandings. Simbloke posted this for a reason in the Fun section of the forum to showcase what kind of nonsense is out there.

 

[mansr]

Interesting. What are the possibilities of a demagnetized disk?

CDs are made from polycarbonate and aluminium, neither of which can be magnetised in the first place.

 

[HarmonicTHD]

CDs are made from polycarbonate and aluminium, neither of which can be magnetised in the first place.

Correct. And even if they could be magnetized (which would require them to contain ferrous alloys - which they don’t of course). It wouldn’t change a thing to their performance.

 

[egellings]

With your vibrating CD in the middle of the energized TV demagnetizer coil, you are probably setting up eddy currents through transformer action in the aluminum layer of the CD, and that current causes the CD to act as an electromagnet, which can then interact with the larger coil to produce the motion you see. The aluminum itself is not magnetic at all. It does, however, conduct current, and that's all that needs to happen to produce the effect you observe.

Let's pretend that the CD could become magnetized. The CD player responds to reflected laser ('magic lantern') light, not magnetism. Who cares if the damn thing got magnetized, anyway?

 

[Killingbeans]

Interesting. What are the possibilities of a demagnetized disk?

Nothing. It just goes from not being magnetized to still not being magnetized.

Well, that's not completely true... There's the possibility that the people who designed, build and sold these things made some money from audiophiles who believed the nonsense

 

[Berwhale]

It might work on one of these 'CDs'...

 

[solderdude]

Try to pick up a CD with a large woofer magnet.....

The CD is a large shorted single wire loop for magnetic fields though so it will react to a magnetic field when that field is applied even when no magnetic materials are being used.

The device is snake oil in solid form...

 

[RayDunzl]

Aluminum is a paramagnetic material.

If I read correctly, it becomes (very) mildly magnetic in a magnetic field, and reverts when the field is removed.

So, it sounds like aluminum temporarily becomes magnetized as you "demagnetize" it, until you remove the demagnetizing field.

Paramagnetism - Wikipedia

en.wikipedia.org

 

[solderdude]

A demagnitizer always creates a varying magnetic field that (relatively) slowly decreases in magnetic strength to 0.

 

[levimax]

So do you think it would be better to demagnetize before or after I use the green magic marker on the edges of my CD's?

 

[Don Hills]

Just demagnetise the marker pen. Saves you the bother of demagnetising each CD.

 

[Killingbeans]

Don't forget to give it a shave frist. Might as well go all in on the woo