| REUK Shop | REUK Blog | Directory | About Us  |  | RSS Web Feed for Renewable Energy UK 

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

home > wind
   Printer Friendly Version Print Article     

The 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 and put them to good use in a wind turbine generator.

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.

View inside a hard disk drive showing the location of the neodymium magnets

Extracting the magnets from an old hard drive is very easy - usually just a small selection of screwdrivers is required. Each magnet you remove from a hard drive will still be attached to a steel backing plate which should be removed.

Hard disk drive magnet still attached to backing plate

This can be difficult - 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.

Bending the backing plate away from the magnet

The following short video shows the full process from opening the hard disk drive, extracting the magnets on their backing plates, to removing those backing plates to leave just the magnets ready to be used.

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.

Polarity of a hard disk drive 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.

5 hard disk drive magnets stuck together to make one very powerful magnet

However you decide to use them, the power of the magnets can be increased by sticking them together (as shown in the photograph above of five magents stuck together). Three magnets stuck together for example should give somewhere between 2 and 3 times the magnetic power of just one magnet.

Wind turbine rotor with hard drive magnets

Above is an example of a wind turbine rotor being made using reclaimed hard drive magnets. Pictured before being set in polyester resin this rotor has a diameter of 300mm and is made up of 16 stacks of hard drive magnets. (Image from FieldLines.com)

Article Last Modified: 10:21, 3rd Oct 2013

Comment on this Article

If you have any comments on this article, please email them to neil@reuk.co.uk.

Related REUK Categories

2006-2014 REUK - All Rights Reserved
Page Last Updated on 7th August 2014 at 11:22:40pm

Site Search

Blog Posts

1. New Raspberry Pi Model B+

2. Pyboard Python for Microcontrollers

3. New REUK Low Voltage Disconnect with Display

4. Valiant PremiAIR 4 Stove Fan

5. Low Voltage Disconnect with LCD Display

6. Solar Water Heating Swimming Pool Controller with Display

7. 12V Programmable PIR Timer with Override

8. Solar Water Heating Pump Controller for Hot Tub with Maximum Temperature

9. Playhouse Lighting Controller with LVD

10. Simple Low Voltage Disconnect with Two Outputs


Make A Bridge Rectifier From Diodes
Make A Bridge Rectifier From Diodes
Make your own single or multi phase bridge rectifier from diodes

Low Voltage Battery Disconnect Circuits
Low Voltage Battery Disconnect Circuits
Find out more about low voltage battery disconnect (LVD) circuits - used to protect batteries

Water Heating with Surplus Solar PV
Water Heating with Surplus Solar PV
Heat water with surplus solar generated electricity

Publish Temperature Sensor Readings to Twitter Raspberry Pi
Publish Temperature Sensor Readings to Twitter Raspberry Pi
Find out how to publish DS18B20 temperature sensor readings to Twitter from Raspberry Pi

Solar Panels on eBay
Solar Panels on eBay
Find out about the solar panels on sale on eBay

Picaxe Programming From Linux
Picaxe Programming From Linux
Find out how to programme PICAXE microcontrollers from the Linux command line

Connecting to Raspberry Pi from PC via SSH
Connecting to Raspberry Pi from PC via SSH
Find out how to operate a Raspberry Pi directly from a Windows PC using SSH

Setting up Static IP Address on Raspberry Pi
Setting up Static IP Address on Raspberry Pi
Find out how to give your Raspberry Pi a static IP address


Popular Items

New solar water heating pump controller with fitted 10A relay
£25.99 each.

Supply a fixed 12.0 Volt DC to your devices (up to 1 Amp output). Includes fitted 1A fuse, 2 spare fuses, and terminals for connection of a switch
£6.99 each.

Multi-function light detector triggered light/dark dawn/dusk controller
£13.95 each.

Protect your 12 volt batteries from being overly discharged
£12.95 each.

Mini multi-functional timer
£13.95 each.

Supply a fixed 12.0 Volt DC to your devices (up to 0.8 Amp output)
£3.99 each.

Bulb holder for 12 Volt LED spotlight bulbs
£1.39 each.

Control up to 8 Watts of LED spotlights to stimulate egg production in birds
£29.99 each.

Convert 12V DC battery power into 230 AC to power portable televisions, computers, video recorders etc. 300 Watt power rating - peak power 600 Watts
£29.99 each.