There are two types of demagnetisers: one uses electricity, and the other is an actual magnet. Electrical demagnetisers consist of two basic types: a hand-held pencil point and a tabletop model. The pencil-point demagnetisers are used for small items such as tape-recording heads. Tabletop models are used for heavier items such as large-bearing assemblies or automotive parts. The actual magnet demagnetiser uses a hole down its centre for magnetising small hand tools such as screwdrivers or pliers. By following a basic procedure, you can use all three of the devices for various applications.
Remove all electrical power from the device you are going to demagnetise. Move all tape-type media from the area, cassette tapes, floppy discs or hard drives. The magnetic field produced by the demagnetiser will destroy information on magnetic particle storage media.
Place a plastic or rubber cover over the tip of the hand-held demagnetiser. Most of these devices come with a protective covering. If the model you have does not, a piece of plastic tape will suffice.
Plug the demagnetiser into the outlet. Make sure you hold the unit well away from any metal object. You can induce an errant magnet field by close contact of the magnetic tip.
Touch the tip gently to the surface of the magnetic field you want to eliminate. Slowly move the tip across the surface in a side-to-side movement, following any contours.
Pull the tip away from the surface and unplug the demagnetiser.
Place the tabletop unit in an area safely away from all electronics. These units will produce a very strong field and can magnetise items many feet from their placement.
Set the item you are treating on the metal surface.
Plug in the demagnetiser. Some units will have a rheostat mounted on the front of the device to adjust the field strength. The manufacturer's documentation will have various settings for strength levels of demagnetising.
Remove the power from the demagnetiser after the allotted time according to the manufacturer's documentation.
Place the magnet on a nonmetal surface. A metal surface will weaken the effectiveness of the magnetizer/demagnetiser.
Induce a magnet field by placing the tip of the hand tool inside the centre hole of the magnet.
Hold the tip in place for approximately 5 seconds, and the tip will be magnetised. Larger metal objects may take slightly longer.
Remove the magnetic field from the hand tool by rubbing the tip or surface of the tool on the outside of the magnet.
Demagnetisers can also be used on older CRT screens to remove magnetic streaks caused by lightening or other induced magnetic fields.
Keep all magnets from media that uses magnetic particles for storage. This includes, cassette tapes, VHS tapes, floppy discs and hard drives.