Mini floppy wind generator is a quite simple DIY project. Even though it looks like a toy, mini wind generator can be used in various situations. Especially if you are camping, fishing, sailing or anyplace where power greed is not available. Our wind generator can be used to recharge AA/AAA batteries (Ni-Cd, Ni-Mh…), mobile phones, MP3 players or for direct energy supply of smaller light bulbs (LED lights) or similar devices that draw up to few watts. The “heart” of mini wind generator is made of parts salvaged from an old 5.25″ floppy drive!
Our first choice was to use stepper motor taken out of old floppy drive for several reasons. PC technology is “aging” very quickly, thus floppy drive can be obtained very cheap, in most cases even free of charge. Stepper motors are very convenient for small wind generators because they do not need any kind of gearing mechanism and the rotor can be attached directly to a turbine (propeller) which is simplifying construction work and also lowers the noise produced by the windmill. Step motor produces stable voltage even with low rpm (200 rpm) which is a great advantage comparing to DC alternators/motors which require 10 to 15 times higher rpm. This is very important, especially during the low wind speed periods.
Supply and charging of connected devices is regulated with small electronic circuit (few diodes, resistor, condenser and integrated circuit), anyone who had earlier experience with soldering iron can construct it.
When it is windy outside, generator of our small windmill produces electric energy sufficient for one small light bulb or charging several batteries. Application is virtually limitless, we have attached USB female connector (with stabilized voltage 5V) to wind generator which makes it possible to connect all modern mobile devices (iPod, iPad, iPhone, MP3 player, smart phone…) that are usually charged via PC USB port.
5.25″ FLOPPY DRIVE WIND GENERATOR – CONSTRUCTION DETAILS
First, we have found an old generation PC286, then opened it and removed 5.25 inch floppy drive unit – Picture 1. As you already guess, floppy drive will serve as a “donor” for the most important part – power generator. After opening floppy drive unit, it is necessary to carefully remove stepper motor (pictures 2 and 3).
We have drilled two holes with stationary drill on the shaft as shown in Figure 4. This we allow us to directly attach the turbine (propeller) of windmill onto stepper rotor, using two screws.
Next, we will construct electronics (Picture 5) which has a task to rectify alternate current (convert it to DC) generated by windmill and to filter and stabilize the voltage precisely at 5 volts (Picture 6) so that we could safely connect any USB device. Although we have used the printed circuit board, you can solder all electronic components directly. You will need soldering iron and some tin with solder paste.
Picture 7 – Wind generator electric schematic diagram
Electronic components should be soldered according to the schematic diagram above. Wires coming out of stepper should be connected to rectifiers, in our case diodes 1N4004 (picture 7 – shown on the left side).
WARNING! Stepper motors usually have 5 wires coming out although you can find those who have 4, 6 or 8 wires. It is important to determine which type of stepper motor you have in order correctly connect the stepper with electronics of wind generator. Here you can find the details on how to connect different stepper motor. It`s very hard to “burn” a stepper but caution is advised anyway!!!
We have bought USB extension cable (Picture 8) on e-bay, cut it in half and connected wires coming out of female USB connector directly to the output of windmill electronics (picture 7 – shown on the right side). USB extension cable has 4 wires, but we need only outer two, plus and minus 5V (Picture 9).
If you want to use wind generator only for battery charging, you can build lot more simplified electronics than the one we have used (Picture 10).
WARNING! Before connecting any USB device it is MANDATORY to check polarity and exact voltage (it has to be between 4.9 and 5.3 Volts) on windmill USB connector using multimeter!!!
Now we have to make the remaining mechanical parts for the wind generator. We need to prepare a bracket and a turbine (propeller). Bracket can be made of aluminum tube diameter 3-4mm, and do not forget to fix it firmly. If you plan to frequently move wind generator, easiest solution is to fix the bracket using the umbrella stand to ensure mobility (Picture 11).
Generator (stepper motor) is most easily fastened directly to the bracket using clamps or using a metal “L” profile, depending on whether you will use horizontal or vertical turbine. We made both versions, it is up to you to decide what you prefer.
If you pick horizontal axis wind turbine, you can create a three-bladed propeller using the meter, pen and scissors for cutting sheet metal. You will need a sheet metal panel 0.8×0.8m, 0.5mm thick. Cut out the pieces and form them as directed on the picture 12, and then attach the turbine to the rotor of stepper motor with screws. In case you do not want to make everything by yourself, you could buy finished propeller very cheap (Picture 14) in any better hardware store. For vertical axis wind turbine, the simplest way is to make a turbine from a plastic bucket (paint container). Cut it in the middle, then fix it onto round wooden or plastic plate (Picture 13). Finally, the whole windmill structure should be fixed on the generator rotor (stepper motor) with screws.
During strong winds (over 10 m/s), mini windmill can produce an average of 5 watts of electricity. This is in principle a maximum with a generator in the form of floppy drive stepper motor, but power also depends on the dimensions of the turbines as well.
Vertical axis wind turbine is most suitable for roof mounting because it is far more efficient at fast and often changing wind direction (turbulent winds). For outdoor usage – you can use windmill version with the horizontal axis and three-bladed turbine.
We are currently preparing new DIY project “100 watt Wind Turbine” which is entirely based on the mini windmill 100 watts is enough power to supply a television set or a laptop. As a generator we will use a stepper again, but this time from an old A3 dot-matrix printer.
Although the power of this wind generator is quite small, it can easily power LED lighting in your backyard (10-20 Hi-Power LED) or serve as autonomous power supply for mobile phone charging on camping. The most important thing is that the successful construction of such mini wind generator encourage you to subsequently make a much stronger wind generator which can reduce consumption of non-renewable energy and decrease carbon footprint.