Magnetic Recording: How Does it Work?

[ammelissa]

I read the info at:
http://www.scienceclarified.com/Io-Ma/Magnetic-Recording-Audiocassette.html

I am looking for someone who can clarify how the second magnetic recording works. I mean, how is it that there is no trace of an old single magnetic aligned material that may interfere with the new ones? Can we say then that magnetic particles can not be traced!

waiting for a reply. Thanks

 

[Danger]

Welcome to PF, Ammelissa.
The erase head eliminates the traces of a previous recording before the write head imprints a new one. If it fails (as happened to me on one of my machines), you can still hear the old signal 'behind' the new one.

 

[ammelissa]

sounds clear. But can you explain to me, please, how physically does this happen? I mean how theoretically the "erase head" functions? Does it randomize the magnets again ... or what ..!

 

[Savant13]

The erase head puts all of the little ferromagnetic bits into the same alignment. It is deviation from this alignment that results in a signal.

 

[ammelissa]

hmm. If this is the case then how such alignment is set. Does the erase head send a certain signal and from where does this signal come on?

 

[Savant13]

hmm. If this is the case then how such alignment is set. Does the erase head send a certain signal and from where does this signal come on?

It's a magnet. That's why you shouldn't expose magnetic recordings to magnets

 

[Danger]

More specifically, it's an electromagnet that works pretty much the same way as the write head, except that it imparts a constant field rather than the patterned, fluctuating field that records a useable signal. It degausses the tape prior to a new recording.