Stupid question no. 3

[d-ray657]

Today is my day for stupid questions (maybe not the only day). I have some old audio tapes that I would like to erase. I have read that it is best to use a bulk eraser. I looked on line and noticed some that were magnetic material rather than electromagnets.

O.K., here's the stupid idea. We have some old car stereo speakers sitting in the garage that have some pretty powerful magnets. How badly would I screw things up using one of those magnets to erase a tape? Does erasing have to be done at a particular level of magnetism - if that is a measurable force? Please, save me from myself.

Regards,

D-Ray

[toxcrusadr]

I tried that recently with a donut magnet used to start pacemakers or some such. Heckuva magnet as far as flux density but not that big in size. I set it right on the tape. It kinda worked, but it made everything into white noise instead of silent. I was curious about that so I'll be watching the answers from the experts.

[ke4jhj]

While a magnet will erase tape, a bulk eraser will do a much more thorough job.

[BrocLuno]

To to this right you need and alternating flux. That usually means an AC driven device. Just like demag'in a head, the field needs to change strength and polarity to erase and an make quiet. You can scramble the music with a single pole, but it won't randomize the tape.

[Web Police]

As was previously stated, to properly erase the previous recording and to restore the low background noise level to that of a new tape, you need to use a bulk eraser that was designed for magnetic media.

[Arkay]

The best way to do it is to put two magnets near each other and pass the tape between them, several passes in both directions and from various angles, and changing the angles between the magnets, too. This will get the particles in the tape "thoroughly scrambled" and result in a complete erasure.

White noise will always result from a crude or random magnetic erasure like that; this isn't much of a problem if you have a good recording head when you are re-recording on the tape. However, a properly-designed eraser will give a quieter background, which of course is preferable. You could do some experiments with different magnet placements and angle passes, to see which arrangement seems to produce the cleanest/quietest erasure.

Basically, the fixed-magnet erasers have two powerful magnets held at 45-degrees from each other , and the tape is passed between them (in close proximity) first in one direction, then in the other direction. [Ooops! I just realized it is more like 90 degrees, forming an "X" that the tape passes through the center of.] That's all that is required for a good erasure, but if you are using random magnets you have, I'd try more passes and angles, just to be sure/safe.

Since your aim is to delete recorded material, not preserve it, you have little to lose by playing around with any magnets, as any good magnetic field will do the job (but different ones with different efficacy). Of course, these fields are "recording" themselves; hence, the white noise. Experiment to minimize it, as mentioned above. Have fun, and good luck!