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In this project, we’ll build a small, vertical-axis wind turbine, or VAWT for short. These are not as efficient as their horizontal-axis cousins, but they are better suited to urban environments where wind can come from all different directions. 

Normally, when you give electricity to a motor, it spins. The same is true in reverse: If you give a motor a spin, it acts as a generator and creates electricity. The wind lantern will use energy from the wind to turn a motor and the resulting energy to light up some light emitting diodes (LEDs) within the base. The wind lantern will use this electricity to create a flickering, glowing indicator of the wind.

LEDs, like any other diodes, allow current to flow through them in only one direction. Bipolar stepper motors have two wire coils. The challenge here is to design a circuit that directs energy generated in each coil through an LED in the correct direction, no matter which way the wind lantern spins. Because even the best intentioned design is no match for NYC wind -it has a mind of its own.  To do this, we’ll build a rectifier circuit for a bipolar stepper motor.

This project was recently featured in an episode of Make: Live - thanks Matt and Becky!  

Step 1: Shopping List

Here are all the parts you'll need, down to the last washer. 

Electronics
• Stepper motor (SparkFun ROB-09238)
• Male header pins (SparkFun PRT-00116)
• Breadboard (like All Electronics PB-400)
• Jumper wires (like SparkFun PRT-00124) or hook-up wire to make your own
• Eight diodes (SparkFun COM-08589)
• One or more LEDs (yellow SparkFun COM-09594 used here, but choose any color)
• One or more 1,000 μF capacitors (SparkFun COM-08982)

Hardware
• 1/4 in acrylic plastic sheet about 15 × 30 in or equivalent (size based on Ponoko P3 template) for gears, disks, and sail holder pieces.  You can download the FREE template here on Thingiverse, or go ahead and buy them from my Ponoko showroom.
• 10 in wide aluminum flashing (usually sold in rolls; you need about 2 ft length for this project)
• 5mm bore shaft collar with set screw (McMaster 57485K65)
• 7 1/2 in bore shaft collars with set screws (McMaster 6166K25)
• 18 in length of 1/2 in outer diameter aluminum tube (McMaster 1658T45 is 8 ft long but a good value if you have the means to cut it down to 18 in—any hacksaw will work (like McMaster 4077A1))
• Two flanged sleeve bearings for 1/2 in shaft diameter (McMaster 2938T12)
• Thrust bearing cage assembly for 1/2 in shaft diameter (McMaster 5909K31) with two matching washers (McMaster 5909K44)
• Three female threaded standoffs, 4 in length, 1/4 in -20 screw size (McMaster 92230A350)
• Six socket head cap screws, 1/4 in -20 thread, 3/4 in length (McMaster 92196A540)
• Six lock washers for 1/4 in screw size (McMaster 92146A029)
• Six flat washers for 1/4 in screw size (McMaster 92141A029)
• Four M3 screws 40mm long (McMaster 91292A024)
• Four M3 lock washers (McMaster 92148A150)
• Four M3 washers (McMaster 91116A120)
• Set of inch and metric hex keys (like McMaster 7324A18)
• Deburring tool (like McMaster 4289A35) and/or rounded file

Step 2: Prepare Aluminum Rod

Put on your safety glasses and cut an 18 in length of the aluminum rod with a hacksaw. Use a deburring tool or file on the inside and outside of the end of the rod to smooth it and avoid cutting yourself.

Make sure your aluminum rod fits through the flanged sleeve bearings, thrust bearing and washers, and the shaft collars.  Look at the tolerances of all the parts on McMaster:
• The aluminum rod has a ±.025 in outer diameter tolerance, which means it can range from 0.475 to 0.525 in.
• The shaft collars don’t give a tolerance for their inner diameters.
• The flanged sleeve bearings say +.001 to +.002 in for the inner diameter.  This means they will be between 0.501 to 0.502 in.
• The thrust bearing says 1/2 in +0.002 to +0.007, which means the inner diameter can range from 0.502 to 0.507 in.
• The thrust washers don’t give any tolerance for the inner diameter. 

This means that the outer diameter of the aluminum rod needs to be smaller than the smallest possible part it needs to fit into, which is the 0.501 in sleeve bearing. As you can see here, we have a good possibility for overlap in an inconvenient direction.

If your aluminum rod is too big for the sleeve bearing, put on your safety glasses, dust mask, and gloves (aluminum dust is not good for you). Grab the aluminum rod with the sandpaper and rotate it while you’re squeezing until you see aluminum dust coming off.  Continue this until the rod fits through all the components.  If you’re lucky enough to have access to a lathe, it could be a time-saver if you have a lot of aluminum to shave off. A bench grinder will work faster than sanding by hand, but it will be harder to maintain the round shape of the rod.

Step 3: Start Assembling Base

Assemble the base (refer to the full picture in step 2 as you go through the steps). Start with the two disks, the hex standoffs, and the 1/4-20 screws, lock washers, and washers. Install the standoffs by sandwiching the acrylic disk, a washer, and a lock washer on each end with a 1/4-20 screw.

Step 4: Part Assembly in Base

Install one of the flanged sleeve bearings in the center hole of the base disk.  The base is the one without the four holes to mount the motor.

Rest a thrust washer, thrust bearing, and then the other thrust washer on top of the flange.

Slide the aluminum rod in from the top. Before it hits the sleeve bearing on the bottom, it should slide through the other sleeve bearing, a 1/2 in shaft collar, a laser-cut gear, two more 1/2 in shaft collars, and finally the thrust washer, bearing, washer stack.

Pull up slightly on the aluminum rod so it’s not hitting your work surface. Use your Allen key set to tighten the set screw in the lowest shaft collar. At this point, the shaft collar is resting on the thrust bearing and attached to the aluminum rod, so you should be able to spin the rod.

Lift the next shaft collar from the bottom up with the gear to about the halfway point inside the base. Tighten the set screw. This shaft collar will be attached to the gear with epoxy putty later, but DO NOT do this yet.

Step 5: Finish Base Assembly

Secure the top sleeve bearing with the top shaft collar.

Step 6: Solder Wires and Mount Motor

Before you continue up the rod, this is a good time to mount your motor. First, cut the wires to about 8 in long and solder a set of four male headers to the wires. Red and green should be next to each other on one side, and blue and yellow on the other.

Remove the screws that hold the motor together. Use the longer M3 screws from the shopping list to mount the motor from the back, on the underside of the top disk. Sandwich an M3 washer and lock washer with each screw.

Slide the other gear onto the motor shaft and use the 5mm shaft collar to secure it temporarily. Adjust the height of both shaft collars until the gears are at the same height and mesh well. Now you can break out the epoxy putty and secure the gears to their respective shaft collars.

Step 7: Continue Adding Parts Up the Rod

Continue up the aluminum rod. Slide on a 1/2 in shaft collar, one of the plastic sail holders, and then another 1/2 in shaft collar. Pull the lower shaft collar up so it’s not resting on the top of the base and secure it to the rod with its set screw.  Then pinch the plastic sail holder with the shaft collar on top of it, and secure the assembly with a set screw. When you rotate the whole assembly by the shaft, it should rotate smoothly, and the sail holders should rotate with the shaft.

Cut out three sails for your wind turbine to catch the wind. There’s no right answer here, and you have a few different slots in the sail holders, so just use scissors to cut the aluminum flashing in a length you think will work. Then cut 1/2 in tabs into each corner to slide into the slots. Bend over the tabs to secure the sails.

Do the same shaft collar, sail holder, shaft collar assembly on the top of the sail to finish this section of the build.  It should spin with very little friction when you turn it by hand with the aluminum rod.

Step 8: Now, the Electronics

We need to create a circuit like the one shown here. Use the eight diodes and jumper wires to create this circuit on your breadboard as shown. It will tell any electricity generated in each coil of the motor to go to the same place: the power column on the bottom of the breadboard. Make sure all your diodes are facing the right direction, and don’t forget to jump the ground columns across the board.  Here's a schematic too if that's easier. 

Notice the LED in the center and the two capacitors at the sides of the board. Plug the long leg of your LED into the power column and the short one into ground. Before you add the capacitors, give the wind lantern a spin and watch the LED flicker!

Try adding at least one capacitor as shown. The negative marked side should go to ground, the other to power. The capacitor will store energy while the wind lantern is creating it, and release it when it is not. The resulting effect here is a smoother flicker on the LED. Try adding more LEDs and more capacitors until you get a smooth glow when you spin the aluminum rod. You can also place diffuser paper over the side of the lantern to create a pleasing glow.

Step 9: Put It to Work

Now take it outside! See if it works with real wind. We had success on a street corner in Manhattan and on the roof of Eyebeam Art + Technology Center’s two-story building as you can see in this video - thanks to awesome intern Sam Galison for helping with the project!

Step 10: When I Win the Laser Cutter...

I first got addicted to using the laser cutter at Eyebeam Art + Technology Center when I was a resident there last spring.  I was able to use if for lots of the projects in the book I wrote called Making Things Move: DIY Mechanisms for Inventors, Hobbyists, and Artists.  When I win this one, I will be able to continue working on projects at the edge of art and technology and using them to teach others about making both for "real" projects and for art and fun. 

I'm now part of a new lab at NYU-Poly where I work as a research assistant while pursuing my PhD in Mechanical Engineering, and we don't yet have our own fabrication tools.  I'm working on some fun projects, like creating a low-cost robotic hand to test space suit gloves, and having a laser cutter will help take me through several iterations of a design with less cost and time than would be possible any other way.  We're also getting a DARwIn-OP humanoid robot in the lab, which is all open hardware, and I'll be modifying it and outfitting it with sensors to measure energy consumption (and of course post about the progress!).  Having a laser cutter will also help immensely here. 

On top of that, I've introduced my fiance to laser cutting and now we have a lot of projects for our wedding that need one!  From laser cut fabric flowers to engraved favors for our guests, we have less than two months to pull everything together.  And we'll continue making and spreading the DIY bug long after that - we already have a list of projects for our new apartment!
<p>Goodness I love this instructable. I'd love to build a more simple version of this, but that seems a tad impossible.</p>
where did you get your gears from?
I made them! They are part of the laser cut file included here. You can use an online service like Ponoko.com or approach your local hackerspace for some help.
y hasint sombody used a car alternater for the generator woldint that be mor efacint <br>
This is a wonderful idea Mrs dustynrobots.Thanks for sharing .<br><br>Que Ideia maravilhosa, obrigado por compartilhar
great idea but in order for the masses to understand this you need to put it in super lamen terms.<br>
I have used dc motors and they will give more power for the size com pared to steppers. You just have to be sure that you get a permanent magnet dc motor. you can find these all over ebay or even from some kids toys.
Great - any projects you can link us to?
I forgot to say that a great resource for this size PM motors is any copier repair place. They take in trades and often will let you strip old machines they have on hand. Copy machines are full of pm motors. Just dont take any that have a circuit board attached to them, they are 3-phase brushless motors and no good for this application. Bring your voltmeter with and if in doubt, you should be able to read a voltage by spining a PM motor even by hand. Happy hunting.
Check out www.otherpower.com . They have tried most ways to generate homebrew electricity. Hours of good reading and learning from others mistakes so you dont have to repeat them.<br>Unfortunately, I am good at doing projects but stink at recording the progress and instructing others.
It would be an interesting experiment to put different kinds of motors in this to compare performance. Stepper motors don't seem like they'd be the most efficient, but who knows.<br><br>I've wanted to do something like this using a salvaged disk drive (CD or HDD), using the spindle motor as the generating device. Half the mounting difficulties should already be taken care of...<br>
That's a good idea. I've done a few wind projects in the past and steppers seem to work well because they have very little resistance when you try to turn them but give a decent amount of power out. If you tried to do that with a DC motor that was easy to spin you would get almost nothing, and a DC gear head motor that could potentially give you more power is hard to turn because of the gear ratio. BUT if you can prove me wrong and find better motors to use for this, I would love to hear about it!
I'm doing a similar project myself and the choice of motor definitely seems like the most difficult part. Through my tests I've found some dc motors and stepper motors that work decently, and some that produce hardly any voltage at a wind turbine normal rpm. I'm interested to know what type of voltage and power you are generating with this stepper motor?
I can't say I know, sorry. But for the LEDs to light that means I'm pulling at least 3 volts and maybe 30mA from the wind, probably more (definitely when it's going faster). I haven't burnt out any LEDs yet so that's probably a good ballpark to get an upper bound. I will try to get a current/voltage sensing thing together to measure this. I tried to avoid paralysis by analysis when choosing a motor and just decided to get started!
I suspect that a DC brush motor (e.g. the hobby motor from a toy car) would be more efficient (the ratio of (mechanical) power in to (electrical) power out) than a stepper motor at each motor's peak efficiency. However, a brush motor barely generates any electricity at low speeds, so you'd need to gear it up a lot. A stepper motor is probably more efficient at very low speeds, so it's easy to either do a 1:1 gearing as you've shown, or to just drive it directly from the VAWT shaft.<br><br>I'll have to consider this for future projects &mdash; I bought a bunch of beefy steppers off eBay for just this purpose, and I have a bunch more from dead printers and such.
Exactly what I'm thinking - although I haven't tried it with DC motors really. Let us know how you get on with your steppers!
Beautiful Machine! <br>I've been experimenting with these after finding a free download of a VAWT with 2 or 3 vanes on: <br>http://www.clockworkrobot.com/downloads/index.htm <br>It's a PDF though of course through a Screencapture program, you can make &quot;JPG's&quot; and thus re-size and re-shape as you want. <br>You can also &quot;Reverse the process&quot; by building a card container and rotating the vanes inside it to produce &quot;A Wind&quot;... <br>Just a pity you can't &quot;Make a Wind&quot; to power the VAWT which produces the electricity to power the &quot;Wind Blower&quot;! <br>
I simply love how rugged this thing is. Well it's just really huge for what it's function is, and scale. I really love this design, it's not going for full efficiency, but it's still using alternative energy to produce light, which we all use everyday anyways.
A number of stepper motors I've salvaged out of old scanners, printers, hard drives, floppy drives, CD drives, and tiny ones in cameras, (they're used in some for the focus and zoom) will drive a LED directly, Since a spun shaft on a stepper motor will output AC on at least 4 of the combinations of wires coming out of the motor, the LEDs can be mounted directly, and since the &quot;D&quot; in LED stands for diode, it will rectify the AC to a half-wave anyway. I don't see the need for additional diodes to make this a very simple wind turbine. I like the design! Thanks for the ideas...
Like your comment!
Would one stepper motor salvaged from CD drive be capable of charging simple garden light replacing the solar panel? Got six garden lights with some old panels right here and plenty of CD drives...
How about making the rectifier out of diodes??? Get to see'em changing as the motor turns, and faster at higher windspeeds.
very sell-able clean piece . a mini vawt with same function can be made for cheaper or free ,but of course less marketable than this . Sweet . I always like the mix of clear and chrome .
The only way to make this more awesome is to have different color lights light up as the wind speed gets higher.<br>
Ohh good call - lemme think if I could do that without a microcontroller. Maybe just putting different colors in with different resistors would do the trick? Green LEDs need less voltage than most others, so maybe as the wind picked up you would get green first then other colors would come in? Hmmm
Find out what your maximum voltage output is and put in a battery to charge.<br>The battery will store the charge and Tame the ' Wild Voltage ' and allow the LED to be used at its operating value. Combine that with an LED Controller and.......
I like the use of two wheatstone bridges as it allows for a more detailed teaching tool for other than single phase electric generation.<br><br>What kind of voltage is it generating?<br><br>What did the motor come out of?<br><br>If you had a center support and stringers (purlins) on the wings they would hold a better air foil.<br><br>Nice Job!
This is really cool, the only thing I have to say is that maybe a DC motor would work better than a stepper motor because of the removal of the need for 8 diodes, you would only need one or two. But they are hard to find that are as easy to mount as this and look as good.<br>Also, maybe you can upgrade it to charge a battery like those solar lights you put in your yard.<br><br>Really awesome job though.
<em>&quot;...as you can see in the video&quot;</em><br><br>Er... what video?
i was wondering that too, until i realised that the pic above with him holding the device in the air from the rooftop....that the first frame. the video is loading...slowly. <br><br><br>:)
Good catch! I thought I could upload videos but maybe not? Either way I put a link to the video on flickr now. Thanks for the heads up.
You can embed videos from most video-hosting sites.<br><br>If you use YouTube, you have to use the &quot;old&quot; code, but if you tried to embed from Flickr and it didn't work, could you post bug report for the admins to see?<br><br>
awesome, thanks for updating !
Great build!
<strong>&nbsp;</strong><br> A very well-engineered build.<br> Have you measured what sort of off-load voltage you're getting from this in a good wind?&nbsp; As is, the capacitors will smooth the voltage but not regulate it in any way.&nbsp; The forward voltage drops of the LEDs will determine the terminal voltage and the brightness will vary with wind speed.<br> It would be interesting to include rechargeable batteries (3 in series if you're getting over 4.5V or 2 if it's less) to store excess energy in windy conditions.&nbsp; You'd need to have a resistor in series with the LEDs for this. You'd have the advantage of constant brightness and some continuity when the wind drops.<br> <br>
Thanks! And good points - no I didn't meter it actually, just tested with a few things, and found that at realistic wind speeds and this size of turbine there wasn't a ton of current flowing, so decided to go with LEDs.

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