Introduction: Low-tech Wind Turbine With Old Printer Motor
1- A wooden plank (minimum 10mm thick)
2- A piece of flat steel (minimum 2mm thick)
3- A stepper motor from a printer (with it's connectors)
4- A PVC tube (diameter between 55mm and 100mm; thickness minimum 3mm)
5- A bicycle inner tube
6- Some wood screws
Electric circuit :
3- Stepper motor from a printer
8- A support made from plastic, to take the different system components (you could e.g. use a flat part of the printer housing)
9- Two rectifier diodes or bridge rectifiers
10- One capacitor, 1000µF 16V
11- A voltage stabilizer LM7805 for fixing the voltage at 5V or LM7812 for fixing the voltage at 12V
11'- Instead of the tension stabilizer you could also use a voltage amplifier or a DC/DC booster or even more advance it by supplying the USB connector with a voltage between 0,9 and 5 Volts.
12- An USB connector
Step 1: How It Works
This tutorial shows how to build a small wind turbine from old printer stepper motor or photocopier. It is able to e.g. charge a mobile phone.
1 - Rotation of the blades
- Powered by the wind, the propeller, also called rotor, starts to move. The blades rotate.
- The rotor has 4 blades and is mounted on a mast in order to get more wind.
2 - Production of electricity
- The rotor propels a stepper motor.
- From the rotors rotation energy the stepper motor produces an alternating current (AC)
3 - Electric circuit
The circuit "handles" the alternating current from the motor output, so that it can be used to charge a mobile phone or another device via USB.
It consists of:
- The rectifiers, which "rectify" the tension from the motor output in order to provide a direct current (DC).
- A capacitor which allows a continuous power supply, although the wind doesn't blow at a constant speed.
- A tension stabilizer which limits the tension produced by the motor at the desired voltage, e.g. 5V.
In order for the wind turbine to start rotating, a minimum wind speed of 10-15km/h is necessary.
Step 2: Steps of Construction
- Preparing the motor
- Motor axis
- Preparing the rotor blades
- Fins and base for rotor blades
- Tension stabilizer
- Connecting the USB port
Motor protection - Waterproofing
Step 3: Wind Turbine - Motor
Choosing the motor
In general, the more steps the motor has, the lower the speed at constant voltage. Important technical data for the selection of the motor are : - The maximum or nominal voltage (measured in volts): Vmax - The current per phase (measured in amperes / phase): A/ph - Number of steps or step angle (measured in °)
For example, a stepper motor with an angle of 3.6° will have 360/3.6 = 100 steps, a 1.8° motor will have 360/1.8 : 200 steps . If you had to choose between two motors with identical characteristics (Vmax and A/ph), prefer the motor with the highest number of steps (here the 1.8° motor since it has 200 steps), it will require a lower rotation speed to deliver a satisfactory voltage.
The choice of motor will also be conditioned by the maximum voltage (Vmax). A motor characterized at 3V will deliver a much lower power than a motor characterized at 50V at the same rotation speed. Choose your motor (within the limit of the available choice) according to the desired application and the required power.
1 - Cut the 6 wires coming out of the stepper motor, strip and twist them.
Testing the motor
In order to find out which of the 6 wires has the highest output voltage, all possible motor output torques must be tested and the two highest selected.
2 - Using a screwdriver, a voltmeter set to " AC " and alligator clips, test the pairs of wires. Note the tension for each pair. (picture 1)
3 - Select the two wire pairs with the highest output voltage (here 10V, this may vary depending on the motor). These will then be connected to the electrical circuit of the wind turbine.
* Tip: Mark with colored tape the two selected couples so they don't get mixed up with each other.
Step 4: Wind Turbine - Motor Axis
1 - Cutting a metal plate of 80x30 cm. Drill it with 5 holes of diameter 4mm.
* Tip: You can use figure 1 above to cut and drill the plate.
2 - Weld the motor shaft to the central hole of the metal plate (picture 2).
Step 5: Wind Turbine - Blade Preparation
1 - Draw and cut the blades in a PVC tube. (figure 3).
* Tip: You can help yourself from the diagram 2 above to draw the shape of the blades.
Figure 3 shows the cutting direction.
2 - Sand the edges of each of the blades: the leading edge must be rounded, and the trailing edge sharpened.
3 - Drill the blades: the drilling is carried out as close as possible to the trailing edge so that the latter can be fixed flat on the plate that carries the blades. (image 4)
Your blades are ready!
Step 6: Wind Turbine - Fins and Blade Bases
1 - In a wooden board, draw and cut out the fin. (image 5)
* Tip: You can use figure 3 above to draw the shape of the fin.
2 - In the same board, cut out a square the size of your engine (here 80x80cm) which will be used to accommodate the blades previously cut out in order to join them together. (diagram 3 - base of the blades).
3 - On the aileron, mark the location of the motor so that it can be forced into the shape. (diagram 3 - motor)
* Note: The dimensions of this part depend on the size of your motor.
4 - Sand the edges of the aileron for better aerodynamics and better rendering. (frame 5)
Step 7: Wind Turbine - Assembly
1 - Screw the blades (cut out in step 3) to their base (cut out in step 4).
2 - Screw the base of the blades to the metal plate. Use the holes drilled in the metal plate in step 2.
3 - Check that there is the same angle between each of the blades.
Step 8: The Electrical Circuit - Rectifiers
The electrical circuit is as shown in "Figure 4".
At the output of the engine, we get alternating current (AC). However, to charge a battery or light a lamp, it is necessary to have direct current (DC). Two rectifiers are used to transform alternating current into direct current: they "rectify" the voltage at the output of the motor.
Each rectifier has 4 legs: The two central legs are the alternating poles of the capacitor. The two outer legs are the positive and negative poles of the capacitor.
* Tip: on the rectifier head each of these 4 poles are marked
1 - Solder the stepper motor voltage outputs (previously selected) to the alternating inputs of each rectifier: the first torque with the alternating poles of the first rectifier, and the second torque with the alternating poles of the second rectifier.(image 7).
* Tip: It is possible to use heat shrink tubing to cover the connections to protect the system.
2 - Solder the negative outputs of the two rectifiers together, then solder the positive outputs of the two rectifiers together. "(picture 8).
Step 9: The Electrical Circuit - Capacitor
The energy supplied by the wind turbine is not constant because the
wind speed is constantly changing. The overload must therefore be temporarily stored in order to to be able to redistribute it consistently. A capacitor is used for this purpose.
The capacitor is a polarized component: - the positive terminal is the longest leg - the negative terminal is the shortest leg
1 - Solder the negative poles together and then the positive poles together at the rectifier output.
* Tip: If the legs of your components are too short to weld together, you can connect them with electrical wires.
Step 10: The Electrical Circuit - Voltage Regulator or Voltage Booster
The voltage regulator makes it possible to recover a 5V output current.
*Note: Each controller is different, if you want a 12V output, for example, buy your controller accordingly. Here to connect a USB port we'll use a 5V one.
The voltage regulator has 3 different rods : - 1 entry - 1 common - 1 exit
1 - Solder the negative pole of the capacitor with the common of the voltage regulator. Solder the plus of the capacitor to the input of the voltage regulator.(image 10)
Alternative advised: use a voltage booster that will provide an output voltage of 5V (USB) with an input voltage ranging from 0.9 to 5V.
Step 11: The Electrical Circuit - Connecting the USB Port
When you place your connector on a table with the plastic tab facing up, the right tab is your positive terminal, and the left tab is your negative terminal.
1 - Solder a red wire to the positive terminal and a black wire to the negative terminal. These will be the output wires of your wind turbine, to which you can connect a battery, a light bulb, etc, and in this case a USB port.
2 - Solder the red wire to the regulator output and the black wire to the regulator common.
Your circuit's ready to go. You can connect a telephone to it, provided there is wind of course
Step 12: Motor Protection - Waterproofing
Cover the engine and the inner tube electrical circuit: this will protect them from rain or sea spray.
Step 13: Use
Connect a mobile phone or other device with a USB connection to the electrical circuit and let it charge for a few hours. In an average wind, it takes 5 hours of charging time for a phone battery.
Step 14: Notes and References
- This tutorial has been created by the Low-tech Lab team during our stopover in Senegal as part of the Nomade des Mers expedition.