Ever wanted to build a wind charger but not sure where to start ? Well now you can enter the world of wind power with this mini model wind charger that produces around 75milli watts of green recycled power. Easily constructed and made of lightweight materials so particularly suited to gusty locations. This little windmill would make a nice addition to a set of solar lights, boosting their power on overcast/rainy days, simply connect the output to the batteries in the solar light.
Heres what you need:
10 X Paper Coffee cups
An old CD
Small scrap of plywood anything above 6mm thickness will do.
A stepper motor from an old printer/fax/scanner/till etc (the older the machine the better usually)
8 X 1N4001 General purpose diodes.
General purpose glue, must adhere to metal.
Miscellaneous small wires
Battery holder to suit batteries
Electrical insulation tape
Note - Not all stepper motors will work well here you must experiment!
Multimeter or ammeter (optional)
Anemometer handy too but not at all necessary.
The video below shows the mini windmill producing some power, the full scale of the meter is 50ma so it's producing around 10 - 30ma typically at wind speed of around 6 - 13mph. It doesn't start charging until around 8.5mph. You can lower the cut-in speed (wind speed that it starts charging at) by just using one ni-cad (1.2v instead of 2.4v). The cut in speed also depends on the amount of cogging your stepper motor has.
There isn't much wind in my garden being surrounded by garden fences, houses and the like, you will get much better performance if you raise the turbine up above everything, but it isn't really worth building such a tall tower for such a small turbine.
The cups are fitted onto the CD by cutting a slot into the sides of the cups. You need to cut a slot about 2" long at the half way point. To make all of the slots the same size, I used a piece of paper cut to size to mark them out. When you have cut the slots test them to make sure they all slide onto the CD.