Hard Disk Drive Magnets For Wind Turbines
Hard Disk Drive Magnets For Wind Turbines
Obtain super strong magnets from old hard disk drives to use in wind turbine alternators
windThe most expensive parts of a
wind turbine alternator are the
magnets and the
enamelled magnet wire. In a previous article we have introduced cheap and easy to make
PVC wind turbine blades. Here you will learn how to obtain magnets for free.
Hard Disk Drive Magnets
50% of the world's
neodymium magnets are currently used in computer hard disk drives (HDD) with each HDD typically containing two magnets. The magnets are used in the
actuator - a device which moves the
actuator arm on the tip of which is the head which reads and writes data to/from the ultra-delicate
platters. Driving the arm using magnets means that mechanical wear and tear is not an issue - unlike old-fashioned stepper motor powered hard drives.
Removing the magnets from an old hard drive is very easy - usually just a cross-head (phillips) screwdriver is required. Click here to view a 77 second video from
metacafe on
extracting magnets from an HDD.
When you remove a
magnet from a hard drive it will still be attached to a steel
backing plate (see below) which should be removed.
This can be difficult, however the easiest way is to put one corner of the backing plate into a bench vice and bend the other corner of the plate using a pair of
vice grips.
WARNING! Sometimes the magnet will break instead of coming away from the backing plate. Ensure that any pieces of broken magnet are kept well out of the reach of children since a couple of swallowed pieces of magnet sticking together in the intestine could be fatal.
Neodmium Magnets in Hard Disk Drives
The
magnets used in hard disk drives are very strong
neodymium (rare earth) magnets. Typically a magnet will have a north pole on one face, and a south pole on the other face. Hard drive magnets differ in that they act like two magnets stuck together side by side. On one face there is a north pole on the left and a south pole on the right, on the other face there is a south pole on the left and a north pole on the right.
This is shown in the image below with the white labels pointing to the top face of the magnet, and the yellow labels pointing to the (hidden) bottom face of the magnet.
Looking side-on the
polarity of the magnet can also be represented as follows:
Therefore, in using these magnets to make a
wind turbine alternator you have two choices. The first is to cut each hard disk magnets in half (using a non-magnetic cutting disk) to make two
standard magnets with one entire face a north pole and one entire face a south pole. Alternatively they can be used as is, but the coils in the alternator must be sized to straddle just one pole at a time.
However you decide to use them, the power of the magnets can be increased by sticking them together (as shown in the photograph above). Three magnets stuck together for example should give somewhere between 2 and 3 times the magnetic power of just one magnet.
Article Last Modified: 15:25, 14th Apr 2007
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