# Demagnetiser



## lev

HI ALL

i seem to remember reading somewhere that it is possible to make a demagnetiser from an electric motor

is it simply removing the rotor and then wiring the coil to plug into the mains electric and of course ensuring that the coil wiring cannot be touched

does it matter as to what size the motor is as i have tried this with a small electric motor about the size of a sewing machine motor but when i switch it on and insert twezzers through the coils i cant feel any vibrations through the tweezers

hope this makes sence im afraid my knowledge of electrics is somewhat limited

regards

lev


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## mel

Sorry lev, if you have to ask at this level, you shouldn't be messing with the mains.







You could well end up *DEAD!* h34r:

Please don't go poking metal tweezers about inside coil formers from stripped down motors connected to the mains, it's *very dangerous.* :yes:

Try to find someone who knows about this locally and visit to see what they have/use before you do yourself any damage - I couldn't recommend advice over the net for a project like this where any competent person can't see or supervise exactly what you are doing.









As an aside, an older independent radio or tv repair guy may still have a bulk tape eraser/demag lying about which might do the job safely, but that's a long shot nowadays.


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## clockworks

I wouldn't try something like this myself. Why risk electrocuting yourself when you can buy a proper demagnetiser for about Â£20?


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## martinzx

Â Check this out for less $15 delivered worldwide a tenner sterling.............

http://cgi.ebay.ca/W...=item5d2ae5919a

I hope I am not breaking any rules putting in linkÂ Â Â


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## clockworks

Bargain - looks identical to the one that I've been using for a couple of years.


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## lev

hi all

thanks very much for your replies will ditch the motor idea and try that one for a tenner of ebay

regards

le


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## tixntox

I have one similar and it's brought a number of watches back to life! 

Mike


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## Chromejob

There's been a discussion elsewhere about how traveling puts automatic movements, particularly those with peek-a-boo casebacks, off their regulation due to all the airport scanning. Making demagnetisers a necessity. But I don't think I'd buy a cheap one from overseas, no matter the feedback.

I believe I saw an old one ("Magnaflux?") on offer, supposedly an old watchmakers' model. Worth looking at?


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## Davey P

On the subject of demagnetisers, can anyone out there explain how they work? Not necessarily the technical (or "witchcraft") bit, but just how you know when a watch needs demagnetising, and what the process involves. Cheers.


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## clockworks

Been a long time since I did physics at school, but I'll have a go!

It's normally the balance spring that gets magnetised, causing the coils to "stick" to each other, making the watch run fast. The magnetic fields are generally very weak, so the coils don't stick solidly - the watch still works, but the balance oscillates faster than it should.

A demagnetiser/degaussing coil runs off the AC mains supply, so it puts out a field that reverses direction 100 times a second. If the watch is moved through the field, it's effectively random. It jumbles up the minute magnetic poles in the hairspring's structure, making them cancel each other out - effectively demagnetising the spring.


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## mel

Clockworks has it right - it's the electrical equivalent of :bangin: bashing a magnetised object with a hammer to demag it :yes:

Remember the experiment with the wire wrapped round a nail to make an electro-magnet - then you stroked a nail across a magnet and magnetised it that way, then demag'ed it with a hammer ? That's the one! :yes:

I'm relieved you intend to buy a "proper" demag coil/tool, much better than relying on resuscitation techniques over the internet!


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## Davey P

clockworks said:


> It's normally the balance spring that gets magnetised, causing the coils to "stick" to each other, making the watch run fast. The magnetic fields are generally very weak, so the coils don't stick solidly - the watch still works, but the balance oscillates faster than it should.


Thanks for that, now please excuse my obvious ignorance but are we talking about quartz or manual watches here? The reason I ask is, I bought a joblot of Swatch watches and hardly any seem to work after fitting a battery, so I was wondering if a demagnetiser might be the magic answer (or are they just generally crap watches?). Seems a shame to bin them if I can somehow rescue a few...


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## clockworks

Mechanical watches. I suppose it's possible for a quartz watch to get magnetised, but they don't have springs.


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## Davey P

Cheers mate, I thought I read somewhere that quartz watches sometimes need demagnetising, hence my confusion. I'll get my coat!


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## clockworks

It's possible, but I've not seen a magnetised quartz watch myself. That could be because I mostly own and work on mechanicals.


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## DaveS

Do not demagnetise a quartz movement. The rotor in the stepper motor of a quartz movement is a small magnet, so if you demagnetise the rotor the watch will never work again.

Kind regards

Dave


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