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This small wind turbine developed by High Tech Handyman in 2009
The objective was to build a wind turbine that would produce 
12 to 14 volts of useful energy at very low wind speeds, while 
at the same time, learning the basics of wind turbine design.

Learn more about the development of this wind turbine...










Development of the Alternator and Electronics

This is the small wind turbine alternator. It's made from very basic materials:

Plexiglas, Steel washer, Rare Earth Magnets, Sewing machine bobbins, Magnet wire, Plastic wood deck plank, Idler wheel from an old 8-track tape deck, plus some electronic components not shown in this picture.









The rotor hub is an idler wheel from an old 8-track tape deck, mounted to a Plexiglas disk with 1/2" holes drilled to accept the 1/2" rare earth magnets. Sandwiched between the 2 Plexiglas disks are steel washers required to direct the magnetic energy in the direction of the coils. I used Crazy Glue to bond the washers to the Plexiglas. No glue was used on the magnets.

It's very important to understand, the magnets alternate between north and south. 
The 8 magnets are positioned in a circular pattern N-S-N-S-N-S-N-S. 
This is what makes it an alternator!









This is the side of the rotor where the blades will be attached. Those outer holes are tapped to accept machine screws. In the final design, I added one more washer at the center to avoid the Plexiglas from flexing and cracking when tightening the inner screws.

Question: Would the rotor be more efficient magnetically if the washers were replaced with one large solid metal disk?  I'd like to know the answer to that question, but I have not yet performed the required tests. Do you know the answer? If you do, send me an Email.










Here I'm preparing to perform the initial tests related to different magnet wire guages, different magnet sizes, stacking magnets, rotor speed, etc. The gray backing is plastic wood decking material purchased from the local home center, cut down to size. It's 5 inches square and very stable compared to wood which i felt would expand and contract too much with temperature and humidity.









The center bearing is the other half of the idler mechanism taken from an old 8-track tape deck. 1/4 inch wooden dowel pins make for excellent mounting posts for the bobbins. These are Singer sewing machine bobbins I purchased on eBay. In this pic, I'm experimenting with different washers behind the coils  to increase the efficiency in order to produce more voltage from each coil. 

Question: In this design, we are using 8 magnets and 12 coils. I'm not exactly 
sure why, but I believe I've seen similar alternator designs that used the same 
number of magnets and coils. Do you know? If you do, send me an Email.











In the final design I used the configuration above with large washers ground down as shown. The one disadvantage of these washers occurs when increasing the magnet size to the point where drag is imposed upon the rotor as the magnets are drawn to the metal washers behind the coils. So there is a bit of a balancing act to contend with when selecting magnet size and washers behind the coils. 

Question: What would happen if I replaced all the individual washers 
with one solid metal plate? I have not tested that theory yet. Do you know? 








These coils are #28 magnet wire wound on Singer sewing machine bobbins. I'd estimate about 300 turns per bobbin. Keep in mind that I eventually went to #36 magnet wire in order to increase the voltage output. I needed about 1200 feet of #36 magnet wire to wind all 12 bobbins.







Notice here that I have two 1/2 inch magnets stacked in each of the 8 positions. This was needed to increase the voltage output. Keep in mind that I finally went to two 3/4 inch magnets in each of the 8 positions.

The trick here is to design the rotor & bearing assembly precise enough to allow those magnets to get as close to the bobbins as possible for maximum efficiency and highest voltage output. 







These are solid #24 insulated wires with the very fine coil wires soldered to the ends on the other side. Labels go.. A1, B1, C1, A2, B2, C2, A3, B3, C3, A4, B4, C4. Where A, B, C represents the 3 phases and 1, 2, 3, 4, represent the 4 coils per phase. See the schematic below for a better idea how these wires get connected.










Learn more about the development of this wind turbine...



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