Wind Lantern: LEDs powered by a vertical axis wind turbine

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

Comments

[SatCenterEngDes]

where did you get your gears from?

[dustynrobots]

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.

[joehudy]

y hasint sombody used a car alternater for the generator woldint that be mor efacint

[Nobin]

This is a wonderful idea Mrs dustynrobots.Thanks for sharing .

Que Ideia maravilhosa, obrigado por compartilhar

[bomb]

great idea but in order for the masses to understand this you need to put it in super lamen terms.

[haroldj1]

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.

[dustynrobots]

Great - any projects you can link us to?

[haroldj1]

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.

[haroldj1]

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.
Unfortunately, I am good at doing projects but stink at recording the progress and instructing others.

[westfw]

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.

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...

[dustynrobots]

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!

[jolshefsky]

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.

I'll have to consider this for future projects — I bought a bunch of beefy steppers off eBay for just this purpose, and I have a bunch more from dead printers and such.

[dustynrobots]

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!

[ddrocketman]

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?

[dustynrobots]

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!

[Felix on Wheels]

Beautiful Machine!
I've been experimenting with these after finding a free download of a VAWT with 2 or 3 vanes on:
http://www.clockworkrobot.com/downloads/index.htm
It's a PDF though of course through a Screencapture program, you can make "JPG's" and thus re-size and re-shape as you want.
You can also "Reverse the process" by building a card container and rotating the vanes inside it to produce "A Wind"...
Just a pity you can't "Make a Wind" to power the VAWT which produces the electricity to power the "Wind Blower"!

[MaXoR]

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.

[Xonk61]

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 "D" 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...

[boocat]

Like your comment!

[Vinsu]

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...

[rtufty]

How about making the rectifier out of diodes??? Get to see'em changing as the motor turns, and faster at higher windspeeds.

[BtheBike]

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 .

[Eye Poker]

The only way to make this more awesome is to have different color lights light up as the wind speed gets higher.

[dustynrobots]

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

[Dr.Bill]

Find out what your maximum voltage output is and put in a battery to charge.
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.......

[Dr.Bill]

I like the use of two wheatstone bridges as it allows for a more detailed teaching tool for other than single phase electric generation.

What kind of voltage is it generating?

What did the motor come out of?

If you had a center support and stringers (purlins) on the wings they would hold a better air foil.

Nice Job!

[jj.inc]

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.
Also, maybe you can upgrade it to charge a battery like those solar lights you put in your yard.

Really awesome job though.

[Kiteman]

"...as you can see in the video"

Er... what video?

[p3ngwin]

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.


:)

[dustynrobots]

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.

[Kiteman]

You can embed videos from most video-hosting sites.

If you use YouTube, you have to use the "old" code, but if you tried to embed from Flickr and it didn't work, could you post bug report for the admins to see?

[p3ngwin]

awesome, thanks for updating !

[scraptopower]

Great build!

[AndyGadget]

 
A very well-engineered build.
Have you measured what sort of off-load voltage you're getting from this in a good wind?  As is, the capacitors will smooth the voltage but not regulate it in any way.  The forward voltage drops of the LEDs will determine the terminal voltage and the brightness will vary with wind speed.
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.  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.

[dustynrobots]

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.