How to make a stepper motor with your own hands. How does a stepper motor work? How a stepper motor works
While riding a bicycle past summer cottages, I saw a working wind generator:
Large blades slowly but surely rotated, the weather vane oriented the device in the direction of the wind.
I wanted to implement a similar design, albeit not capable of generating enough power to supply "serious" consumers, but still working and, for example, charging batteries or supplying LEDs.
Stepper motors
One of the most effective options for a small homemade wind turbine is to use stepper motor(ШД) (eng. stepping (stepper, step) motor) - in such a motor, the rotation of the shaft consists of small steps. The stepper motor windings are in phase. When current is applied to one of the phases, the shaft moves one step.
These engines are low-speed and a generator with such an engine may be gearedlessly connected to a wind turbine, Stirling engine, or other low-speed power source. When used as a generator of a conventional (collector) engine direct current to achieve the same results, a 10-15 times higher speed would be required.
A feature of the shagik is a fairly high starting torque (even without an electrical load connected to the generator), reaching 40 grams of force per centimeter.
Coefficient useful action generator with stepper motor reaches 40%.
To check the functionality of the stepper motor, for example, a red LED can be connected. By rotating the motor shaft, you can observe the glow of the LED. The polarity of the LED connection does not matter, as the motor generates alternating current.
A treasure trove of such powerful enough motors are five-inch floppy drives, as well as old printers and scanners.
Engine 1
For example, I have a stepper motor from an old 5.25 ″ drive, which was still in operation ZX Spectrum- compatible computer "Byte".
Such a drive contains two windings, from the ends and the middle of which conclusions are drawn - total is removed from the engine six wires: 
first winding (eng. coil 1) - blue (eng. blue) and yellow (eng. yellow);
second winding (eng. coil 2) - red (eng. red) and white (eng. white);
brown (rus. brown) wires - leads from the midpoints of each winding (eng. center taps).
disassembled stepper motor
On the left you can see the rotor of the motor, on which you can see the "striped" magnetic poles - north and south. To the right is the stator winding, which consists of eight coils.
Half winding resistance is ~ 70 ohms.
I used this engine in the original design of my wind turbine.
Engine 2
The less powerful one at my disposal stepper motor T1319635 firms Epoch Electronics Corp. from scanner HP Scanjet 2400 It has five conclusions (unipolar motor): 
first winding (eng. coil 1) - orange (eng. orange) and black (eng. black);
second winding (eng. coil 2) - brown (eng. brown) and yellow (eng. yellow);
red (eng. red) wire - pins connected together from the midpoint of each winding (eng. center taps).
The resistance of the half winding is 58 ohms, which is indicated on the motor housing.
Engine 3
In the improved version of the wind turbine, I used a stepper motor Robotron SPA 42 / 100-558 produced in the German Democratic Republic and designed for a voltage of 12 V: 
Wind turbine
There are two options for the location of the impeller (turbine) axis of the wind generator - horizontal and vertical.
The advantage horizontal(most popular) location the axis, located in the direction of the wind, is a more efficient use of wind energy, the disadvantage is the complexity of the design.
I chose vertical arrangement axes - VAWT (vertical axis wind turbine), which greatly simplifies the design and does not require wind orientation ... This option is more suitable for roof mounting, it is much more effective in conditions of rapid and frequent changes in wind direction.
I used a type of wind turbine called the Savonius wind turbine. Savonius wind turbine). It was invented in 1922 Sigurd Johannes Savonius) from Finland. 
Sigurd Johannes Savonius
The operation of the Savonius wind turbine is based on the fact that the resistance (eng. drag) to the incident air flow - the wind of the concave surface of the cylinder (blade) is larger than the convex one.
Aerodynamic drag coefficients ( English drag coefficients) $ C_D $
two-dimensional bodies:
concave half of the cylinder (1) - 2.30
convex half of the cylinder (2) - 1.20
flat square plate - 1.17
three-dimensional bodies:
concave hollow hemisphere (3) - 1.42
convex hollow hemisphere (4) - 0.38
sphere - 0.5
These values are given for Reynolds numbers (eng. Reynolds numbers) in the range $ 10 ^ 4 - 10 ^ 6 $. The Reynolds number characterizes the behavior of a body in a medium.
Resistance force of the body to the air flow $ (F_D) = ((1 \ over 2) (C_D) S \ rho (v ^ 2)) $, where $ \ rho $ is the air density, $ v $ is the air flow velocity, $ S $ - cross-sectional area of the body.
Such a wind turbine rotates in the same direction, regardless of the direction of the wind: 
A similar operating principle is used in the cup anemometer (eng. cup anemometer)- a device for measuring wind speed: 
Such an anemometer was invented in 1846 by the Irish astronomer John Thomas Romney Robinson ( John Thomas Romney Robinson):
Robinson believed that the cups in his four-cup anemometer moved at a speed equal to one third of the wind speed. In reality, this value ranges from two to a little more than three.
Currently, three-cup anemometers are used to measure wind speed, developed by Canadian meteorologist John Patterson ( John Patterson) in 1926: 
Generators on DC brushed motors with vertical microturbine are sold at eBay for about $ 5: 
Such a turbine contains four blades located along two perpendicular axes, with an impeller diameter of 100 mm, a blade height of 60 mm, a chord length of 30 mm and a segment height of 11 mm. The impeller is mounted on the shaft of a DC micromotor with the marking JQ24-125H670... The rated supply voltage of such a motor is 3 ... 12 V.
The energy generated by such a generator is sufficient for the glow of a "white" LED.
Rotational speed of the Savonius wind turbine cannot exceed wind speed , but at the same time such a construction is characterized by high torque (eng. torque).
The efficiency of a wind turbine can be estimated by comparing the power generated by the wind turbine with the power contained in the wind blowing through the turbine:
$ P = (1 \ over 2) \ rho S (v ^ 3) $, where $ \ rho $ is the air density (about 1.225 kg / m3 at sea level), $ S $ is the swept area of the turbine (eng. swept area), $ v $ is the wind speed.
My wind turbine
Option 1
Initially, the impeller of my generator used four blades in the form of segments (halves) of cylinders cut from plastic pipes:
Segment sizes -
segment length - 14 cm;
segment height - 2 cm;
the length of the chord of the segment is 4 cm;
I installed the assembled structure on a fairly high (6 m 70 cm) wooden mast from a bar, attached with self-tapping screws to a metal frame: 
Option 2
The disadvantage of the generator was the rather high wind speed required to spin the blades. To increase the surface area, I used blades cut from plastic bottles:
Segment sizes -
segment length - 18 cm;
segment height - 5 cm;
segment chord length - 7 cm;
the distance from the beginning of the segment to the center of the axis of rotation is 3 cm.
Option 3
The strength of the blade holders proved to be an issue. At first I used 1mm perforated aluminum strips from a Soviet children's designer. After several days of operation, strong gusts of wind led to the break of the planks (1). After this failure, I decided to cut out the blade holders from foil-coated PCB (2) 1.8 mm thick: 
The flexural strength of the PCB perpendicular to the plate is 204 MPa and is comparable to the flexural strength of aluminum - 275 MPa. But the modulus of elasticity of aluminum $ E $ (70,000 MPa) is much higher than that of textolite (10,000 MPa), i.e. texolite is much more elastic than aluminum. This, in my opinion, taking into account the greater thickness of the textolite holders, will provide a much greater reliability of fastening the blades of the wind generator.
The wind generator is mounted on a mast: 
The trial operation of the new version of the wind turbine has shown its reliability even under strong gusts of wind.
The disadvantage of the Savonius turbine is low efficiency
- only about 15% of wind energy is converted into shaft rotation energy (this is much less than can be achieved with wind turbine Daria(eng. Darrieus wind turbine)), using lift (eng. lift). This type of wind turbine was invented by the French aircraft designer Georges Darier. (Georges Jean Marie Darrieus) - US patent of 1931 No. 1,835,018 .
Georges Darier
The disadvantage of the Darrieus turbine is that it has a very poor self-start (to generate torque from the wind, the turbine must already be spun).
Conversion of electricity generated by a stepper motor
The stepper motor leads can be connected to two bridge rectifiers, assembled from Schottky diodes to reduce the voltage drop across the diodes.
Popular Schottky diodes can be used 1N5817 with a maximum reverse voltage of 20 V, 1N5819- 40 V and a maximum forward average rectified current of 1 A. I connected the outputs of the rectifiers in series in order to increase the output voltage.
It is also possible to use two midpoint rectifiers. Such a rectifier requires half as many diodes, but at the same time output voltage is reduced by half.
Then the ripple voltage is smoothed using a capacitive filter - a 1000 μF 25 V capacitor. To protect against an increased generated voltage, a 25 V zener diode is connected in parallel to the capacitor. 
diagram of my wind turbine
electronic unit of my wind generator
Wind turbine application
The voltage generated by the wind generator depends on the magnitude and constancy of the wind speed.
With the wind swaying the thin branches of trees, the voltage reaches 2 ... 3 V.
With the wind swaying thick branches of trees, the voltage reaches 4 ... 5 V (with strong gusts - up to 7 V).
CONNECTING TO JOULE THIEF
The smoothed voltage from the capacitor of the wind generator can be supplied to - low-voltage DC-DC converter 
Resistor value R is selected experimentally (depending on the type of transistor) - it is advisable to use a variable resistor of 4.7 kΩ and gradually reduce its resistance, achieving stable work converter.
I assembled such a converter based on germanium pnp-transistor GT308V ( VT) and a pulse transformer MIT-4V (coil L1- conclusions 2-3, L2- conclusions 5-6): 
CHARGE OF IONISTORS (SUPERCONDENSERS)
Supercapacitor (supercapacitor) supercapacitor) is a hybrid of a capacitor and chemical source current.
Supercapacitor - non-polar an element, but one of the terminals may be marked with an "arrow" - to indicate the polarity of the residual voltage after it has been charged at the factory.
For the initial research, I used a supercapacitor with a capacity of 0.22 F for a voltage of 5.5 V (diameter 11.5 mm, height 3.5 mm):
I connected it through a diode to the output through the germanium diode D310.
To limit the maximum charging voltage of the supercapacitor, you can use a zener diode or a chain of LEDs - I use a chain of two red LEDs: 
To prevent the discharge of an already charged supercapacitor through the limiting LEDs HL1 and HL2 I added another diode - VD2.
To be continued
I had a stepper motor lying around and I decided to try to use it as a generator. The motor was removed from an old dot matrix printer, the inscriptions on it are as follows: EPM-142 EPM-4260 7410. The motor is unipolar, which means that this motor has 2 windings with a tap from the middle, the resistance of the windings was 2x6 ohms.
The test requires another motor to spin the stepper. The construction and mounting of the motors are shown in the figures below:
I lost the roller from the engine, so I put on the paste ...
We smoothly start the engine so that the rubber band does not fly off. I must say that at high speeds it still flies, so it did not raise the voltage above 6 volts.
We connect a voltmeter and start testing, first we measure the voltage.
We set the voltage on the PSU to about 6 volts, while the engine consumes 0.2 Amperes, for comparison, the engine ate 0.09A at idle
I don't need to explain anything and everything is clear from the photo below. The voltage was 16 volts, the speed of the spinning engine is not large, I think if you spin it harder, you can squeeze out all 20 volts ...
We connect through a diode bridge (and do not forget the capacitor, otherwise you can burn the LEDs) a tape with super-bright LEDs, the power of which is 0.5 watts.
We set the voltage to a little less than 5 volts, so that the stepper motor after the bridge gives out about 12 volts.
Shines! At the same time, the voltage dropped from 12 volts to 8 and the engine began to spin a little more slowly. Short-circuit current without led strip was 0.08A - let me remind you that the unwinding motor did NOT work on full power, and do not forget about the second winding of the stepper motor, it is just impossible to parallel them, and I did not want to assemble the circuit.
I think you can make a good generator from a stepper motor, attach it to a bicycle, or make a wind generator based on it.
Do you even understand what you are writing? Or do you write in order to support a person in his endeavors and he, having spent money on components for his system, ended up with an absolutely inoperative thing? You answer: "The engine, as a generator will fit" - yes, it will, but where did you get the 1.1-1.5A? At what voltage? At what speed of rotation of the rotor? Then you write: "The power standard of 1m tape, like, 5W ..." - there is no power standard here, and tapes are about 5W and about 14W, and about 7W per meter, etc., and this is a very large spread. We continue: "Since you wound up so much, it may well be enough to charge the battery" - this, in general, what does it mean? The fact that the more complex, sophisticated and intricate the scheme, the greater its return and efficiency? Complete nonsense. To charge a 12V motorcycle battery, you need about 14-15V at a current of about 0.6-0.7A (for a capacity of about 7A / h). Are you sure that the system is capable of producing such parameters for a long time? After all, to charge a discharged motorcycle battery, 2-3 hours is not enough. Do you also think that you can charge from 18V? Yes, you can, but the electrolyte will boil off in a week, if not earlier, and the plates will sprinkle. Good recommendation! They are unpretentious in charging - this does not mean that they can be charged with any voltage. Then you write: "It will be very great, because I suddenly forgot to turn off the light and the battery sat down even before it has time to recharge" - say as if the battery is charged only during daylight hours))) This is a wind turbine, not a solar battery. With a properly working system, with a constant wind, the battery should not be discharged at all, even if you forgot to turn off the light. But the photocell idea itself is good from an automation point of view. Next: the LED strip will probably work, as you say, and at 30 volts, however, how long? Resistances limit the current, yes, but it will increase in proportion to the increase in voltage, and not remain constant! Diodes do not like exceeding the operating current very much. So, the result is known: overheating of the diodes and, as a result, a sharp decrease in the service life, or their failure is extremely fast. Next, you write: "The capacity is also not critical, add 1 more film capacitor for 1 microfarad" - for what? Is that a noise filter? Why then 1mkF? And why is there a filter at all? And, if not a filter, but a ripple-smoothing element, then its capacity is critical! Capacitance is actually the main parameter of a capacitor. And 1μF is an empty space for a system described by a person, it will not smooth out anything. Even 1000uF, which the author of the questions wanted to establish, is very little for his idea. I would understand if it was 5000-7000 or even 10000 μF, or even more. At the end, the person asks if the motorcycle battery is enough for the tape to glow all night, and you answer that, of course, that's enough. Did you study physics in school? Or are you still studying? Was it your guess with your finger in the sky or at least some elementary calculation? Let's estimate very roughly: a person wrote that he wants to install 10-15m of tape. Even if we take the minimum values, i.e. 10m of tape with a power of 5W / m, then by simple calculations we get 50W of power. Dividing the power of the tape by the voltage of the battery (approximately 12.8V), we get the current: 50 / 12.8 = 3.9A. The capacity of a conventional motorcycle battery is approximately 7A / h. That. you can estimate how long the tape will work from a fully charged battery: 7 / 3.9 = 1.79 h = 1 h 47 min., i.e. almost two hours. This is not the whole night. In addition, the minimum parameters are taken into account, and if the length of the tape or / and its power are greater, the operating time from the battery will decrease proportionally. Something like that.
I would not write all this, but the fact is that a tape costs money, a battery and a photo relay too ... And this is a lot of money, and people who have received approval and support for their idea in the comments of people who do not understand the essence and nuances of the process, will happily run to the store, spend money on components, and in the end will receive a system that is inoperable in principle, initially. No need to give advice without understanding the issue!
Every year people are looking for alternative sources. Homemade power plant from the old car generator will come in handy in remote areas where there is no connection to the general network. She will be able to charge freely rechargeable batteries, and will also ensure the operation of several household appliances and lighting. Where to use the energy, what will be generated, you decide, as well as assemble it yourself or purchase it from manufacturers, which are abundant on the market. In this article, we will help you figure out the do-it-yourself wind generator assembly diagram from those materials that any owner always has.
Consider the principle of operation of a wind power plant. Under a fast wind flow, the rotor and propellers are activated, after which the main shaft comes into motion, rotating the gearbox, and then generation occurs. We get electricity at the exit. Therefore, the higher the rotational speed of the mechanism, the greater the productivity. Accordingly, when placing structures, take into account the terrain, relief, and know the areas of territories where the speed of the vortex is high.
Assembly instructions from a car generator
To do this, you will need to prepare all the components in advance. The most important element is the generator. It is best to take a tractor or bus, it is capable of generating much more energy. But if this is not possible, then most likely it is worth doing more. weak aggregates... To assemble the device you will need:
voltmeter
battery charging relay
blade steel
12 volt battery
box for wires
4 bolts with nuts and washers
clamps for fastening
Assembling a device for a 220v home
When everything you need is ready, proceed to the assembly. Each of the options can have additional details, but they are clearly specified directly in the manual.
First of all, assemble the wind wheel - the main structural element, because it is this part that will transform the wind energy into mechanical. It is best if it has 4 blades. Remember that the smaller the number, the more mechanical vibration and the more difficult it will be to balance it. They are made from sheet steel or an iron barrel. They should not wear the same shape as you saw in the old mills, but resemble the wing type. Their aerodynamic drag is much lower, and the efficiency is higher. After you, with the help of a grinder, cut out a windmill with blades with a diameter of 1.2-1.8 meters, it, together with the rotor, must be attached to the axis of the generator by drilling holes and connecting with bolts.
Assembling the electrical circuit
We fix the wires and connect them directly to the battery and voltage converter. It is required to use everything that at school in physics lessons you were taught to tinker when assembling electrical circuit... Before starting development, think about what kW you need. It is important to note that without the subsequent alteration and rewinding of the stator, they are not at all suitable, the operating speed is 1.2 thousand -6 thousand rpm, and this is not enough for energy production. It is for this reason that it is required to get rid of the excitation coil. To raise the voltage level, rewind the stator with a thin wire. Typically, the resulting power will be 150-300 watts at 10 m / s. After assembly, the rotor will magnetise well, as if power was connected to it.
Rotary self-made wind generators are very reliable in operation and economically profitable, their only imperfection is the fear of strong gusts of wind. The principle of operation is simple - a vortex through the blades makes the mechanism spin. In the process of these intense rotations, the energy is generated, the voltage you need. Such a power plant is a very good way to provide electricity to a small house, of course, in order to pump water out of the well, its capacity will not be enough, but it is possible to watch TV or turn on the lights in all rooms with its help.
From a home fan
The fan itself may be inoperative, but only a few parts are required from it - this is the stand and the screw itself. For the design, you need a small stepper motor soldered by a diode bridge in order for it to produce constant pressure, a bottle of shampoo, a plastic water pipe approximately 50 cm long, a cap for it and a lid for a plastic bucket.
A sleeve is made on the machine and fixed in the connector from the wings of the disassembled fan. This bushing will hold the generator. After fixing, you need to start making the case. Cut off the bottom of the shampoo bottle using a machine or manually. During cutting, it is also required to leave a hole of 10 in order to insert an axle, turned from an aluminum rod, into it. Attach it with a bolt and nut to the bottle. After all the wires have been soldered, another hole is made in the bottle body to output these same wires. We stretch them and fix them in a bottle on top of the generator. They must match in shape and the body of the bottle must reliably hide all of its parts.
Shank for our device
In order for it to catch wind streams from different directions in the future, assemble the liner using a pre-prepared tube. The tail section will be secured with a twist-off shampoo cap. A hole is also made in it and, after putting a plug on one end of the tube, they stretch it and fix it to the main body of the bottle. On the other hand, the pipe is cut with a hacksaw and the wing of the shank is cut out of the lid of the plastic bucket with scissors, it should have a round shape. All you need to do is simply trim off the edges of the bucket that secured it to the main container.
We attach the USB output to the back panel of the stand and put all the received parts into one. It will be possible to mount the radio or recharge the phone through this built-in USB port. Of course, it does not have a strong power from a household fan, but still it can provide lighting for one light bulb.
DIY wind generator from a stepper motor
A device made from a stepper motor generates about 3 watts even at low rotational speeds. The voltage can rise above 12 V, which allows charging a small battery. A stepper motor from a printer can be inserted as a generator. In this mode, the stepper motor generates an alternating current, and it can be easily converted to direct current using several diode bridges and capacitors. You can assemble the scheme with your own hands. The stabilizer is installed behind the bridges, as a result, we get a constant output voltage. An LED can be installed to monitor eye tension. In order to reduce the loss of 220 V, Schottky diodes are used to rectify it.
The blades will be PVC pipe. The workpiece is drawn on the pipe and then cut out with a cutting disc. The span of the screw should be about 50 cm, and the width should be 10 cm. It is necessary to grind a sleeve with a flange to the size of the SM shaft. It is pushed onto the motor shaft and secured with screws; plastic “screws” will be attached directly to the flanges. Also carry out balancing - pieces of plastic are cut from the ends of the wings, the angle of inclination is changed by heating and bending. A piece of pipe is inserted into the device itself, to which it is also bolted. As for the electrical board, it is better to place it at the bottom, and bring the power out to it. Up to 6 wires come out of the stepper motor, which correspond to the two coils. They will require slip rings to transfer electricity from the moving part. Having connected all the parts together, we proceed to testing the structure, which will start revolutions at 1 m / s.
Wind turbine made of motor-wheel and magnets
Not everyone knows that a wind generator from a motor-wheel can be assembled with your own hands in a short time, the main thing is to stock up on the necessary materials in advance. The Savonius rotor is best suited for it, it can be purchased ready-made or independently. It consists of two semi-cylindrical blades and an overlap, from which the rotor rotation axes are obtained. Choose the material for their product yourself: wood, fiberglass or pvc pipe, which is the simplest and the best option... We make the junction of the parts, where you need to make holes for fastening in accordance with the number of blades. You will need a steel swivel mechanism to withstand any weather.
From ferrite magnets
A wind generator with magnets will be difficult for inexperienced craftsmen to master, but you can still try. So, there should be four poles, each will contain two ferrite magnets. They will be covered with metal pads with a thickness of a little less than a millimeter to distribute a more even flow. There should be 6 main coils, rewound with a thick wire and should be placed through each magnet, occupying a space corresponding to the length of the field. The fastening of the winding circuits can be on the hub from the grinder, in the middle of which a pre-machined bolt is installed.
The flow of energy supply is regulated by the height of the stator fixing above the rotor, the higher it is, the less sticking, respectively, the power decreases. For the windmill, you need to weld a support-stand, and fix 4 large blades on the stator disk, which you can cut out of an old metal barrel or a lid from a plastic bucket. At an average speed of rotation, it produces about 20 watts.
Wind turbine design on neodymium magnets
If you want to learn about the creation, you need to make the basis of the car hub with brake discs, this choice is quite justified, because it is powerful, reliable and well balanced. After you clean the hub of paint and dirt, proceed to the arrangement of the neodymium magnets. They will need 20 pieces per disc, the size should be 25x8 millimeters.
The magnets should be placed taking into account the alternation of the poles; before gluing it is better to create a paper template or draw lines dividing the disk into sectors so as not to confuse the poles. It is very important that they, facing each other, have different poles, that is, they are attracted. Glue them with super glue. Lift the curbs around the edges of the discs, and wrap tape or plasticine in the center to prevent spreading. In order for the product to operate at maximum efficiency, the stator coils must be sized correctly. An increase in the number of poles leads to an increase in the frequency of the current in the coils, due to this, the device, even at a low frequency of rotation, gives great power... The coils are wound with thicker wires in order to reduce the resistance in them.
When the main part is ready, the blades are made, as in the previous case, and they are fixed to the mast, which can be made from an ordinary plastic pipe with a diameter of 160 mm. In the end, our generator, operating on the principle of magnetic levitation, with a diameter of one and a half meters and six wings, 8m / s, is capable of providing up to 300 watts.
The price of disappointment or an expensive weather vane
Today there are many options for how to make a device for converting wind energy, each method is effective in its own way. If you are familiar with the method of manufacturing equipment that generates energy, it will not matter on the basis of what to make it, the main thing is that it meets the conceived scheme, and gives good power at the output.
While riding a bicycle past the summer cottages, I saw a working wind generator. Large blades slowly but surely rotated, the weather vane oriented the device in the direction of the wind.
I wanted to implement a similar design, albeit not capable of producing enough power to supply "serious" consumers, but still working and, for example, charging batteries or supplying LEDs.
One of the most effective options for a small homemade wind turbine is to use stepper motor(ШД) (eng. stepping (stepper, step) motor) - in such a motor, the rotation of the shaft consists of small steps. The stepper motor windings are in phase. When current is applied to one of the phases, the shaft moves one step.
These engines are low-speed and a generator with such an engine may be gearedlessly connected to a wind turbine, Stirling engine, or other low-speed power source. Using a conventional (collector) DC motor as a generator, a 10-15 times higher speed would be required to achieve the same results.
A feature of the shagik is a fairly high starting torque (even without an electrical load connected to the generator), reaching 40 grams of force per centimeter.
The efficiency of the generator with stepper motor reaches 40%.
To check the functionality of the stepper motor, for example, a red LED can be connected. By rotating the motor shaft, you can observe the glow of the LED. The polarity of the LED connection does not matter, as the motor generates alternating current.
A treasure trove of such powerful enough motors are five-inch floppy drives, as well as old printers and scanners.
For example, I have a stepper motor from an old 5.25 ″ drive, which was still in operation ZX Spectrum- compatible computer “Byte”.
Such a drive contains two windings, from the ends and the middle of which conclusions are drawn - total is removed from the engine six wires:
first winding (eng. coil 1) - blue (eng. blue) and yellow (eng. yellow);
second winding (eng. coil 2) - red (eng. red) and white (eng. white);
brown (rus. brown) wires - leads from the midpoints of each winding (eng. center taps).
disassembled stepper motor
On the left you can see the rotor of the motor, on which you can see the "striped" magnetic poles - north and south. To the right is the stator winding, which consists of eight coils.
Half winding resistance is
I used this engine in the original design of my wind turbine.
Less powerful stepper motor in my possession T1319635 firms Epoch Electronics Corp. from scanner HP Scanjet 2400 It has five conclusions (unipolar motor):
first winding (eng. coil 1) - orange (eng. orange) and black (eng. black);
second winding (eng. coil 2) - brown (eng. brown) and yellow (eng. yellow);
red (eng. red) wire - pins connected together from the midpoint of each winding (eng. center taps).
The resistance of the half winding is 58 ohms, which is indicated on the motor housing.
In the improved version of the wind turbine, I used a stepper motor Robotron SPA 42 / 100-558 produced in the German Democratic Republic and designed for a voltage of 12 V:
There are two options for the location of the impeller (turbine) axis of the wind generator - horizontal and vertical.
The advantage horizontal(most popular) location the axis, located in the direction of the wind, is a more efficient use of wind energy, the disadvantage is the complexity of the design.
I chose vertical arrangement axes - VAWT (vertical axis wind turbine), which greatly simplifies the design and does not require wind orientation ... This option is more suitable for roof mounting, it is much more effective in conditions of rapid and frequent changes in wind direction.
I used a type of wind turbine called the Savonius wind turbine. Savonius wind turbine). It was invented in 1922 Sigurd Johannes Savonius) from Finland.
Sigurd Johannes Savonius
The operation of the Savonius wind turbine is based on the fact that the resistance (eng. drag) to the incident air flow - the wind of the concave surface of the cylinder (blade) is larger than the convex one.
Aerodynamic drag coefficients ( English drag coefficients) $ C_D $
concave half of the cylinder (1) - 2.30
convex half of the cylinder (2) - 1.20
flat square plate - 1.17
concave hollow hemisphere (3) - 1.42
convex hollow hemisphere (4) - 0.38
These values are given for Reynolds numbers (eng. Reynolds numbers) in the range $ 10 ^ 4 - 10 ^ 6 $. The Reynolds number characterizes the behavior of a body in a medium.
Resistance force of the body to the air flow $ =<<1 \over 2>S \ rho
Such a wind turbine rotates in the same direction, regardless of the direction of the wind:
A similar operating principle is used in the cup anemometer (eng. cup anemometer)- a device for measuring wind speed:
Such an anemometer was invented in 1846 by the Irish astronomer John Thomas Romney Robinson ( John Thomas Romney Robinson):
Robinson believed that the cups in his four-cup anemometer moved at a speed equal to one third of the wind speed. In reality, this value ranges from two to a little more than three.
Currently, three-cup anemometers are used to measure wind speed, developed by Canadian meteorologist John Patterson ( John Patterson) in 1926:
Generators on DC brushed motors with vertical microturbine are sold at eBay for about $ 5:
Such a turbine contains four blades located along two perpendicular axes, with an impeller diameter of 100 mm, a blade height of 60 mm, a chord length of 30 mm and a segment height of 11 mm. The impeller is mounted on the shaft of a DC micromotor with the marking JQ24-125p70... The rated supply voltage of such a motor is 3. 12 B.
The energy generated by such a generator is enough for the glow of the "white" LED.
Rotational speed of the Savonius wind turbine cannot exceed wind speed , but at the same time such a construction is characterized by high torque (eng. torque).
The efficiency of a wind turbine can be estimated by comparing the power generated by the wind turbine with the power contained in the wind blowing through the turbine:
$ P =<1\over 2>\ rho S
Initially, the impeller of my generator used four blades in the form of segments (halves) of cylinders cut from plastic pipes:
segment length - 14 cm;
segment height - 2 cm;
the length of the chord of the segment is 4 cm;
I installed the assembled structure on a fairly high (6 m 70 cm) wooden mast from a bar, attached with self-tapping screws to a metal frame:
The disadvantage of the generator was the rather high wind speed required to spin the blades. To increase the surface area, I used blades cut from plastic bottles:
segment length - 18 cm;
segment height - 5 cm;
segment chord length - 7 cm;
the distance from the beginning of the segment to the center of the axis of rotation is 3 cm.
The strength of the blade holders proved to be an issue. At first I used 1mm perforated aluminum strips from a Soviet children's designer. After several days of operation, strong gusts of wind led to the break of the planks (1). After this failure, I decided to cut out the blade holders from foil-coated PCB (2) 1.8 mm thick:
The flexural strength of the PCB perpendicular to the plate is 204 MPa and is comparable to the flexural strength of aluminum - 275 MPa. But the modulus of elasticity of aluminum $ E $ (70,000 MPa) is much higher than that of textolite (10,000 MPa), i.e. texolite is much more elastic than aluminum. This, in my opinion, taking into account the greater thickness of the textolite holders, will provide a much greater reliability of fastening the blades of the wind generator.
The wind generator is mounted on a mast:
The trial operation of the new version of the wind turbine has shown its reliability even under strong gusts of wind.
The disadvantage of the Savonius turbine is low efficiency - only about 15% of wind energy is converted into shaft rotation energy (this is much less than can be achieved with wind turbine Daria(eng. Darrieus wind turbine)), using lift (eng. lift). This type of wind turbine was invented by the French aircraft designer Georges Darier. (Georges Jean Marie Darrieus) - US patent of 1931 No. 1,835,018 .
The disadvantage of the Darrieus turbine is that it has a very poor self-start (to generate torque from the wind, the turbine must already be spun).
Conversion of electricity generated by a stepper motor
The stepper motor leads can be connected to two bridge rectifiers, assembled from Schottky diodes to reduce the voltage drop across the diodes.
Popular Schottky diodes can be used 1N5817 with a maximum reverse voltage of 20 V, 1N5819- 40 V and a maximum forward average rectified current of 1 A. I connected the outputs of the rectifiers in series in order to increase the output voltage.
It is also possible to use two midpoint rectifiers. Such a rectifier requires half as many diodes, but at the same time the output voltage is reduced by half.
Then the ripple voltage is smoothed using a capacitive filter - a 1000 μF 25 V capacitor. To protect against an increased generated voltage, a 25 V zener diode is connected in parallel to the capacitor.
diagram of my wind turbine
electronic unit of my wind generator
In windy weather, the tension idle move at the exit electronic unit the wind generator reaches 10 V, and the short circuit current is 10 mA.
CONNECTING TO JOULE THIEF
Then the smoothed voltage from the capacitor can be applied to Joule thief- low voltage DC-DC converter. I assembled such a converter based on germanium pnp-transistor GT308V ( VT) and a pulse transformer MIT-4V (coil L1- conclusions 2-3, L2- conclusions 5-6):
Resistor value R is selected experimentally (depending on the type of transistor) - it is advisable to use a variable resistor of 4.7 kOhm and gradually reduce its resistance, achieving stable operation of the converter.
my converter Joule thief
CHARGE OF IONISTORS (SUPERCONDENSERS)
Supercapacitor (supercapacitor) supercapacitor) is a hybrid of a capacitor and a chemical current source.
Supercapacitor - non-polar cell, but one of the terminals may be marked with an “arrow” to indicate the polarity of the residual voltage after it has been charged at the factory.
For the initial research, I used a supercapacitor 5R5D11F22H with a capacity of 0.22 F for a voltage of 5.5 V (diameter 11.5 mm, height 3.5 mm):
I connected it through a diode to the output Joule thief through the germanium diode D310.
To limit the maximum charging voltage of the supercapacitor, you can use a zener diode or a chain of LEDs - I use a chain of two red LEDs:
To prevent the discharge of an already charged supercapacitor through the limiting LEDs HL1 and HL2 I added another diode - VD2.
My homemade wind turbine with a stepper motor, My fascinating and dangerous experiments
My self-made wind turbine with a stepper motor While cycling past summer cottages, I saw a working wind generator. The big blades were spinning slowly but surely, the weather vane
A stepper motor as a generator?
I had a stepper motor lying around and I decided to try to use it as a generator. The motor was removed from an old dot matrix printer, the inscriptions on it are as follows: EPM-142 EPM-4260 7410. The motor is unipolar, which means that this motor has 2 windings with a tap from the middle, the resistance of the windings was 2x6 ohms.
The test requires another motor to spin the stepper. The construction and mounting of the motors are shown in the figures below:
We smoothly start the engine so that the rubber band does not fly off. I must say that at high speeds it still flies, so it did not raise the voltage above 6 volts.
We connect a voltmeter and start testing, first we measure the voltage. 
I don't need to explain anything and everything is clear from the photo below. The voltage was 16 volts, the speed of the spinning engine is not large, I think if you spin it harder, you can squeeze out all 20 volts.
We set the voltage to a little less than 5 volts, so that the stepper motor after the bridge gives out about 12 volts.
Shines! At the same time, the voltage dropped from 12 volts to 8 and the engine began to spin a little more slowly. The short-circuit current without the LED strip was 0.08A - let me remind you that the unwinding motor did NOT work at full power, and do not forget about the second winding of the stepper motor, you just cannot parallel them, and I did not want to assemble the circuit.
I think you can make a good generator from a stepper motor, attach it to a bicycle, or make a wind generator based on it.
A stepper motor as a generator? Meander - entertaining electronics
A stepper motor as a generator? I had a stepper motor lying around and I decided to try to use it as a generator. The engine was removed from an old dot matrix printer, lettering
