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The Junior Wind Turbine project.
                                                                                                                                              
For my latest workshop in my daughter’s school I wanted to let the children each make a wind turbine. It wanted it to be functional, powering a small light and it needed to be cheaper than 6 Euro a piece, which ruled out any commercial kits.

The workshop was for 20 kids, which ruled out scavenging hard discs motors or stepper motors and such. Low cost “toy” motors on the other hand need really high rpm to light up a small bulb or a led. Fortunately the type of motors used in solar cell driven toys and kits work better. And these are still available for under 2 Euro.

A small flashlight bulb was actually easier to get to glow than lighting a LED, when driving a 6 to 1 gear on a “solar grade” motor by hand. But it required too much torque for a small and simple wind turbine.

A LED worked with a turbine and a single step 6 to 1 gearing, but only at really high wind speeds, needed to get a high enough voltage. But I wanted the kids see it functioning, without having to wait for a strong wind. To apply a higher gear ratio in one step needed a larger gear wheel which I could not find at a low price. A two step gearing gives to much friction with the cheap and simple construction techniques suitable for a kids workshop (remember we are talking about gearing up, which is more critical to build quality).

But our good friend the Joule Thief came to the rescue. With this little circuit added, the LED lights up at a breeze. Moving the wind turbine by hand easily lights up the LED. I estimate it starts at wind speeds below 10km/h. And everything still holds up at strong winds.

Apart from attaching leads to the motor/generator in advance (“solar” motors are often sold with leads anyway) the circuit is built up without soldering, as I prefer to avoid that when working with 20 kids aged 6 to 12.

All that was left was making some “templates” for the steps that need accuracy and gathering the materials and I was ready for the workshop. Check the result in the video below and read how we built the wind turbines in this Instructable.

My special thanks goes to Emma, for her assistance when taking extra pictures showing the detailed construction steps.

Thanks for the votes for this entrie in the MakerBot Challenge!

Step 1: Materials and Tools

For the turbine and tail vane:
1 piece of 2mm thick balsa 10 cm by 40 cm or 4 pieces 10 cm by 10 cm
4 bamboo (meat) skewers 30 cm long, about 3mm diameter
some cellotape, at least 19mm wide
superglue
large gear (about 60 mm diameter, Opitec part 840088)
a piece of scrap wood, 3 cm thick and about 6 cm by 6cm in size.
some non-stick paper,
1 small stick of hotmelt glue (low temp type when working with kids)
a cabinet screw with an unthreaded part, fitting loosely the gear hole (4mm for the gear mentioned above), about 35 mm long. A brass screw will last longer in humid conditions, I found out screws with a nominal diameter equal to the gear hole, actually fit loosely.
4 washers fitting the screw
paint and varnish (optional)

For the generator:
a “solar grade” toy motor with 7cm leads (FF 130 “solar motor”, Opitec part 224176 works great, but needs leads to be soldered to the motor. The RF 300, Opitec 224154, comes with leads, but is less resistant to rain)
a small pinion gear of the same module as the large gear (Opitec 841187 with adapter 842022)
a (steel spring) clamp fitting the motor/generator (Opitec 225074)
a 25 mm long bolt and nut. I choose M3, allowing for all drilling to be done with a 3 mm bit.

For the Joule Thief:
a ferrite toroid (e.g. Conrad 507997 or 508039)
a 2N3904, BC 337 or equivalent transistor
a 1kOhm resistor
1 to 3 LEDs (the clear ones are easiest to see lighting up in sunlight)
2 times 20 cm of insulated thin gauge electrical wire (twisted strands from telephone or network cable are perfect)
5 small cabinet screws, preferably brass (more durable contact). I choose shortest 3 mm diameter ones I found, allowing for all drilling to be done with a 3 mm bit.

For the mast
a 27 cm piece of 20mm diameter PVC electrical tube
a 75 cm to 1 m long piece of 16 mm PVC electrical tube
2 tie-wraps (pretty small ones are OK)
a marble

Tools:
a junior hacksaw
a flat working surface (theoretically 31 by 31 cm, but take double to work with some comfort)
a hotmelt gun (low temp type when working with kids)
a drill (preferably column-type) and a 3mm drill bit
screwdrivers fitting the screws and bolts used
some templates can be made out of scrap wood as explained in the following steps

Step 2: Making the Turbine Blades

The turbine blades are made by sawing three of the balsa squares as shown. Keeping the turbine very light makes it very forgiving for inaccuracy’s and unbalance, but to help make the blades all the same size, I did make sawing templates.
Three of the skewers are cut in half (it is a good idea to cut of a couple of mm of the sharp point, to limit the risk of anyone hurting herself or himself). Take care of the grain of the wood. It should be close to perpendicular to the cut, or the blades will break easily.

The forth square and skewer are kept aside for the tail vane.

With some cellotape the skewers are provisionally attached to the blades as shown. The assembly is laid down on some anti-stick paper and some superglue is run in the joint, (something I do myself for the younger kids). When the glue has set the rest of the tape is bent over and attached.

Now is a good time to decorate the blades.

Step 3: Turbine Construction

The 3 x 6 x6 cm piece of scrap wood is prepared with a top of anti-stick paper and a central hole. With a small screw the large gear is attached to it. A washer is put in between to keep some distance from the hub, when the skewers are pushed in between as shown. With the skewers evenly distributed under the holes, tighten the screw just enough to keep them in place when the assembly is on the table.

Make sure all the blades are pointing the same direction (clockwise or counter clockwise) and touch the flat working surface with their tip. This is obviously very important to get a good angle. Now, pour hotmelt glue in the hole, taking care not to spill any on the gear's teeth (see how a piece of scrap cardboard can be used the help prevent that). Check if all blades are in the right position and let the glue set, before removing the screw.

You might want to reinforce the glued connection on the other side, but to my experience that is not needed unless the turbine is accidently dropped or something like that.

Step 4: Drilling

The 27 cm piece of 20mm diameter PVC tube is prepared to be the central “support” onto which all other parts are attached. This means first some drilling has to be done. All holes are 3 mm

Only one hole needs to be in an accurate position from one other, the others holes are not critical. First the hole for the motor/generator mount is drilled about 5 cm from and goes completely through. The motor/generator mount is attached with a bolt and nut. There's a little trick to that: first the mount is attached hand tight, with the curve of the metal following the curve of the tube. When it is twisted to its final position the spring metal provides tension, locking the assembly into place.

Now comes the critical hole. It needs to be drilled perpendicular to the first one, and at a distance along the tube determined by the gears and motor/generator used (18 mm with the Opitec parts mentioned above). The motor/generator mount can be bent a little to adjust for small errors, but taking care with this drilling will avoid this. Therefore a template fitting the tube and motor/generator mount was made as shown. This hole goes completely through also.

Now five holes are drilled near the top of the tube, roughly in the pattern shown. These holes need only to go through the tube wall once (don't worry if they go through completely). I adapted the template to help positioning these holes, but that was an overshoot.

Step 5: The Generator Joule Thief (1)

The basics of making a Joule Thief are described in a number of Ibles, so I won’t go into detail, but stick to explaining the solderless construction used here. It is helpful to check out the circuit at Evil Mad Scientist to have some idea of what connections you are making. Obviously the motor/generator replaces the battery.

Prepare the double wound toroid by coiling the pair of twisted wires. Four to five windings should do it.

Loosen the wire ends and put two opposite ends back together (twist them together for now).

Put the pinion gear onto the motor/generator and put it in the clamp as show (pinion facing the other side than the five holes pattern).

Step 6: The Generator Joule Thief (2): Electrical Connections

The electrical connections are made by inserting the right wire ends in the pattern of  five holes and fixing them with the small brass screws. Not only is this an alternative for soldering, we also do not need to strip the wire. The thread of the screws cuts right through it, making the connection.

If you are not sure which one is the positive one, just go ahead and check for what rotating direction the LED lights up after finishing all connections. Switch the motor leads after step 7 if it happens to be the wrong direction.

At the workshop it showed the first insertion of the screw was difficult when connecting more than two wires. This is easy to solve by enlarging the hole slightly with a bradawl.

To test it after assembly, turn the pinion gear quickly as shown in the video in the introduction. You might need to check both directions of rotation to find one working.

Step 7: Mounting the Turbine

Put in the axle screw in the turbine gear from the side of the blades. With 4 washers in between screw it in the tube, taking care the gear aligns with the pinion on the motor/generator. Again, slightly enlarging the hole with bradawl might help. When the screw reaches the second hole, on the other side of the tube, take care to guide it nicely through the hole, or the gear will not be angled correctly.

Check if it runs smoothly and adjust. The gears should have a fairly loose grip on each other. Check if the LEDs light up by moving the assembly through the air by hand (as shown in the video in the introduction). Again, check the other direction if the first one does not work.

The correct direction of rotation is the one with the turbine facing downwind from the tube. If it only works the other way around, switch the motor/generator leads.

Step 8: Tail Vane

Glue one end of the 30 cm skewer to the last 10 by 10 cm balsa square, taking care of the direction of the grain of the wood. The skewer should be glued across the grain of the wood, protecting the balsa from snapping along the grain.

Attach the other end of the skewer to the bottom of the tube with two tie-wraps in cross. Align the tail vane in such a way that it keeps the turbine facing down wind.

Step 9: Installing

Put a marble on the top of this tube and slide on the turbine assembly. The axle screw inside the tube, resting on the marble provides a bearing for the turbine to turn smoothly into the wind. Obviously the wind turbine should be positioned vertically for that.

Step 10: Ideas for Further Developments

This basic junior wind turbine works well, but can use some improvements.

One idea is to in weather proof all electrical connections with something like Plasti Dip. Do not worry about the motor/generator to much. Most toy motors resist rain quite well. To make sure you can put some grease to the axle and all openings.

Varnishing the blades or replacing them with plastic sheet and possibly also the skewers will make it more durable. Although the bamboo skewers and balsa keep quite well.

A furling tail vane could turn the turbine out of too strong winds. A classic furling vane mechanism with counterweight should not be too difficult to make.

A bearing that keeps the turbine attached to the long tube could be helpful in strong winds. A longer 20mm diameter tube would help already. Another idea is to put the marble on a large screw inserted in a plug into the top of the 16 mm diameter tube. Then a small screw is inserted through the wall of the outer tube, locking just under the head of the large screw.

An alternative attachment/bearing with a phone untangler could allow for the generated power to be transferred to an application separated from the rotating turbine.
Another idea is to store the energy in a rechargeable battery, to power the LED(s) at windless evenings.

<p>hi,</p><p>very nice project. would it not be possible to couple the motor directly to the turbine axle, rathern than thru gears ?</p>
Thanks.<br><br>I tried that obviously. Most DC motors need high rpm before delivering any output.<br><br>Stepper motors can give a usual output at lower rpm and without the joule thief circuit, but those cost a lot more. You can find those fore fee in discarded printers (see https://www.instructables.com/id/Hydropower-from-Reuse/ ), but for 20 kids that was no option.
i see. thanks.
<p>Hi</p><p>I just want to thank you for this great simple creation because I am doing a project for school and this will help it a lot. I haven't made it yet but it seems like a great project. thanks</p>
These are really lovely.<br><br>I'm wondering whether I can do this with an after-school club that my daughter attends. They are quite young (5-11) so I might need to do most of the cutting and drilling but they could do the assembly.... humm I think we might be able to do it, even if we split it over more than one session.<br><br>Lovely instructable and a really great project. Thanks.
Thanks you very much.<br><br>It should work for that age group with some preparing and enough adults to help. I did this with a group of 20 children, aged 6 to 12. We were 5 adults (4 of them unprepared) to help them. We did in 3 hours.<br><br>Drilling is something kids can do from a very young age, using a drill press, some template or some foolproof clamping for the work piece, and of course under close supervision. And they absolutely love it. As I only have one drill press, it is a bit of bottle neck, but in the meanwhile they can decorate or do other things.<br><br>Sawing is a bit harder, but most will manage with the simple templates I prepare made from hard wood with a cut and some bits nailed on it to position the workpiece. Some spare wood to redo a piece once in a while, has proven to very useful.<br><br>Actually what did prove hard in this project, was inserting the screws when more than two wires where inserted in a hole. The simple solution was to enlarge these holes wit an awl, before inserting anything. Drilling these holes (but only these) 0,5 mm larger would work to, but it requires a second passing at the drill press.<br><br>I cut the balsa squares, plastic tubes and the wires in advance. Given time and help, the kids could do it themselves, but they would have to take turns cutting it from the larger pieces. So It saves a lot of time time and eases handing out the materials.<br><br>If you have any questions left, please feel free to ask.<br><br>I wish you a lot of success with your ow version!
Thanks for your help - I think I might try a small group first time and see how we go. Am currently trying to source the materials and oddly, 16mm PVC pipe is proving the hardest to find. Any hints on where? 20mm seems to be everywhere but I can't find 16!<br><br>Many thanks.
try mc mastercarr. com they should have every thing u'ill need
It's reasonably common here. But you can use any stick about that diameter. A tube's open end keeps the marble in place wen assembling, but a solid rod will work fine.
Yeah - that was my backup plan - use a piece of dowel and mybe pout a counter-sink hole in the top to keep the marble in place. Plastic is more weatherproof thou' so I thought it was worth asking in case you had a mystery source!<br><br>I might see if I can get some reasonbly straight banboo of the right diameter - that would be more weatherproof than dowel (&amp;cheaper) and is pre-bored!
Bamboo sounds like a great idea. If you increase the overlapping length of the 20 mm outer tube, the diameter of the inner tube, rod or dowel becomes even less critical. Obviously it has to fit with some room to move freely, but even if it is a lot thinner, the turbine will remain reasonably upright when the overlap is long enough. Of course the inner tube or rod should not bend to much in the wind. But that should not be a problem with bamboo.
Just thought I'd let you know that yesterday I did a project day with a half-dozen six year olds based very closely on these wind-turbines.<br><br>I set up the (hand) mitre-saw with a guide so that they could do the sawing, and we used a drill-stand with a template much like yours for the generator and rotor holes. <br><br>For the wiring holes, I made little stickers with five different coloured dots (~4-5mm) on them. They stuck the stickers to the top of the mast pipe and then drilled through each spot. That gave the holes in acceptable positions and meant that the wiring could be along the lines of &quot;orange motor wire into the orange hole&quot; etc. I found that very small stainless woodscrews were better than brass because they are much more pointed and so easier to get started in the hole. Contact with copper wire may make them rust but it will take a while.<br><br>So thanks for posting the instructable. I had some very chuffed little girls and some amazed mums by the time they were picked up at the end of the day.
Wonderful!<br><br>And the stickers sound like a great idea.<br><br>I guess nor the stainless screws nor the wire will corrode that fast. In theory combining two different metals leads to corrosion of the least nobel one. Actually, well passivated stainless steel acts quite inert, so in some conditions it may be that the copper corrodes. But in practice, I expect you will not have corrosion problems within the lifetime of these wind turbines.<br><br>Thanks for sharing.<br>
PS we used 50cm lengths of pipe over 120cm bamboo canes with your marble bearing and they turn fine in the wind.
Oh - and I meant to say - thanks for your reply!.
great instructable can u pls tell me the rates voltage and rpm of ur motor
Thanks,<br> <br> You can find specs on the motors at the site of <a href="http://uk.opitec.com/opitec-web/articleNumber/224079/zz/cID/c3I6U29sYXIgTW90b3IgRkYgMTMwIFNIOQ==" rel="nofollow">Opitec</a>, were I sourced them from.<br> <br> I did not measure the rpm or voltage we obtained with the turbine.<br> <br> If you like this kind of projects, also check out this <a href="https://www.instructables.com/id/Hydropower-from-Reuse/" rel="nofollow">Ible</a> where I used a stepper motor from a discarded printer. <div id="myEventWatcherDiv" style="display: none;"> &nbsp;</div>
thank u so much for the link ur projects are reallyu miraculous !!
This is such a fabulous wiring solution!<br><br>I sometimes do some sciency things with a little after-school club that my daughter attends. Hopefully we can do these generators but either way, I am completely stealing this wiring method!
Thanks, that is what sharing Instructables is for :-)
i didt made the whole thing but i just found a permanent motor and a generator..
You've put a few adults to shame! Kudos kids! <br>
Awesome! I'm going to have to try this with my science club!
Thanks. Please keep informed on the result.
Now I just need to find a source of cheap gears...
In the States I guess www.kelvin.com is the classic source.
Brilliant! If you don't want to make the joule thief circuit, you can buy emergency mobile phone chargers from ebay from around &pound;1.50 each, they are just a joule thief with a battery holder. That might make it even simpler and easier.
Thanks.<br><br>Very interesting tip! I have been scavenging Joule Thief circuits from cheap solar garden lights, but unless one has a good use for the solar cell, that is not the cheapest solution.<br><br>Of course, making the Joule Thief is fun in itself, but depending on the group or the project it could be very welcome to simplify things.
I used them on my thermoelectric generator, they're good and cheap. Here's one in for $1.37 : <a href="http://cgi.ebay.com/Emergency-Battery-Charger-Nokia-SAMSUNG-phone-Mp3-/250643464754?pt=PDA_Accessories&hash=item3a5b83c232">http://cgi.ebay.com/Emergency-Battery-Charger-Nokia-SAMSUNG-phone-Mp3-/250643464754?pt=PDA_Accessories&amp;hash=item3a5b83c232</a><br> <br> Takes a while for shipping though, as all the cheap ones ship from China.<br>
cool but bit unstable
Thanks.<br><br>The wind was very unstable the day of filming, and of course the simple and light construction is indeed very sensitive to any changes in the wind. Actually, the kids like that.
Wow that's amazing.
Thanks

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