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Re: Remagnetizing bar magnets

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5/11/2006 9:17 PM

Re: Remagnetizing bar magnets

I think a 'magnetic array' might work, as long as the spaces between your magnets is as small as possible. If I was making one of those, I would probably use lots of small (1/2"?) square magnets because you can get lots of them close together.

My P90 was a 1955? I got 20 years ago. It's one of the 'glued together' ones. It was 8.6k, but before I remagged it you could barely hear it.

I bought some old magnetism theory texts in a junk shop, supposedly Alnico will lose its charge if you heat it too hot, or drop it, or hit it too hard.

My son raced 1/24 scale slot cars a couple of years ago, the local slot car track remagnetized a Strat pickup for me then for $5.00.

You can also try a auto alternator repair shop - the one local to me also repairs 'old car' generators and has a remagnetizer too.

Ken

5/12/2006 7:34 AM

On 5/12/2006 3:17 AM, Ken said:

quote:
"I think a 'magnetic array' might work, as long as the spaces between your magnets is as small as possible. If I was making one of those, I would probably use lots of small (1/2"?) square magnets because you can get lots of them close together. "

One classic approach is to have the magnets attached to a mild steel bar, which in turn touches the slug poles. This will allow a rare earth magnet to power all poles without being too strong, as one need not pack magnets shoulder-to-shoulder.

quote:
"I bought some old magnetism theory texts in a junk shop, supposedly Alnico will lose its charge if you heat it too hot, or drop it, or hit it too hard. "

Yes, although modern materials are far less sensitive.

Heat too hot. Look in the datasheet for the Curie Temperature, which is that temperature above which a magnetic material becomes non-magnetic. For alnico alloys, the Curie Temperature comfortably exceeds soldering temperature, and so will never be reached in practice. Ferrites have the lowest Curie Temperatures, but still would be hard to achieve without destroying the pickup. I don't recall the Curie Temperature of rare earth magnets, but assume it falls between these limits.

Mechanical Shock. Still true, but it takes a lot to make any real difference.

Old books also talk about aging, where permanent magnets slowly lose strength. Again, this isn't much of an issue with modern materials.

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