Every once in awhile I have an idea that actually works.
One thing that I find annoying is tools that become magnetized for one reason or another.
Screwdrivers, Pliers, Drill Bits, etc. …
I wanted a simple CHEAP demagnetizer.
All I needed was a magnetic core, a coil and an AC voltage.
Here is what I came up with.
I used a motor from a fan.
The one I actually used is from an old microwave oven.
The one in the pictures is from an bathroom exhaust fan but is identical.
I simply removed the rotor assembly and the core copper (optional).
I hooked up a momentary pushbutton switch and a pilot light (optional) and a power cord.
I used a polarized cord and put the pushbutton switch in the hot side.
I mounted it into a plastic box and that was it.
IT WORKS GREAT.
It seems to work best if you rub the item across the top of the core.
I have demagnetized screwdrivers, pliers, drill bits in a matter of seconds.
I even completely demagnetized a flywheel magnet.
It is small enough to be handheld so you can bring the demagnetizer to the object.
Words of caution :
Use a momentary pushbutton switch only.
Make sure the motor you use is rated for the same voltage you plug the device into.
Make sure all electrical connections are solid and safe for the operator.
Bob, this is out of control simple!
I absolutely detest tools/tooling that have become magnetized and have been on the lookout for just such a thing.
I have a $12 Broan 688 fan running in my office and when the bearings shell out and I replace it, I know just what I'm gonna do with the motor's frame.
Thank you, thank you, thank you!
p.s. I have a nice rear axle Hyatt bearing that's gone magnetic too. Hmmm....
Do be a little cautious. It could be embarrassing to go to the store and have your credit or debit card not work.
Now, your wife's cards on the other hand?
I know they are becoming pretty rare but if you have access to an old growler for checking generator and starter armatures anything you drag across one will be demagnetized.
Many years ago at work we used an old electromagnet from a time clock. We magnetized and demagnetized our tools as needed. We found you had to hang on tight to the tool. Later a friend worked at a medical device repair facility and showed what an MRI unit could do to metal projectiles. Probably overkill for this application.
Based on some advice from another source, I revised the motor to make the demagnetized more efficient.
By making the core into a "U" shape, the demagnetizing flux will be much stronger.
I would also like to add a note on using the demagnetizer.
Turn the unit on then move the object to the unit.
It is OK to let the object come in contact with unit.
Draw the object away from the unit at least 6 inches before de-energizing the unit.