Gallery, Projects and General > How to's

Electrical Demagnetizer

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John Stevenson:
Trying to get simpler, what about using a torroid transformer on it's own ?

John S.

Bluechip:
J S

Don't think it would work .. all the magnetic flux is in the toroid .. or should be ..

Dave BC

Bernd:

--- Quote from: websterz on March 20, 2010, 07:46:32 PM ---I regularly make small batches (50 or so) parts out of 4140. After hardening and surface grinding them there is always some residual magnetism in them. I bought a 4x6 surface demag'er from Enco planning to spread the parts out on a thin piece of card stock and treating a whole batch at a time. Plus it will be big enough to do drills, hand tools, etc. Just under $40 with free shipping. Cheaper than scrapping my microwave I guess... :dremel:

--- End quote ---

Being close to a transfer station (junk drop off) I've picked up the dead micro-waves. I've got at least a dozen or so transformers.

The reason I started collecting these was/is I found an article on the net about making your own spot welder using two rewound transformers. I've got the article stored some were on my disk drives.

I'm sure you could find them laying out on the curbside on pickup day.

Bernd

Bernd:

--- Quote from: Krown Kustoms on March 20, 2010, 08:57:07 PM ---Nice utilization of scavenged parts.
I love seeing something so simple turned in to a tool.

So......are you using the bulb as a fuse/circuit breaker? I see it as a good indicator of a 'dead' short but are you going to utilize it in the perminant fixture?
A small neon bulb and a fuse would also act as a indicator to tell you if it was on or not.

I am already looking for a small transformer to build this 'need to have' tool.

Thanks for the idea. -B-

--- End quote ---

I learned this trick back in my early days of model railroading. The club I belonged to used an automotive bulb of a certain size in there power to the track. Shorts occured many times through in the wiring because people would throw the wrong swtich. So instead of buring out power supplies the light would light up and show a short indication. This method never let the magic smoke out.

So concider the bulb as a sort of indicator. If the coil develops an internal short the bulb will light up giving an indication of such. A fuse should always be incorporated into a system like this along with a power on indicator light.

Another thing that's useful is the very, and I mean very, strong magnet that is incorporate with the micro wave emitter. About as strong as the magnets in a disk drive. They are useful also. Another little how to I want to post eventually.

Now all I need to do is make it permanent. And of course with my project list being as long as some criminals arrest list..... well you know the rest.  :lol:

Bernd

Darren:
Nice idea Bernd, my only concern is the voltage on the second winding on a microwave transformer. Usually around 11Kv from the ones I've tested.

I don't suppose the voltage of the transformer makes too much difference for de-magnetising so perhaps a 12V one would be safer?

Just a thought ...

JS, Dave is right, you can't get inside the windings on a toroid like you can with an EI transformer coil ...  :thumbup:

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