It was created as part of my final project for the Design and Technology Major Studio class at Parsons The New School for Design.
Step 1: Collect Materials
Paper towel holder (preferably metal)
12 Aluminum bobbins (NOT steel)
Magnet Wire (lots of it, the thinner the gauge the better -- try for 36 gauge)
8 strong magnets (rare earth preferred)
a wine cork
and these electronics:
- 6 schottky diodes (1N5822)
- Large capacitor, pref, super cap
Step 2: Cut the Pringles Can
Step 3: Mark out the CDs
If you choose to mark you own guides, I found the transparent "CD" that comes with some CD-R spindles was helpful to use as a template.
Step 4: Cut, Sand, and Fit the Cork Into the CDs
a) you can make them as snug as you need to
b) you don't hurt the turbine's efficiency by running a dowel through the middle of it (which, according to some of my research, knocks it down by something like eight percent)
You can take an ordinary wine cork and cut it in half, then work the pieces over with a saw and some sandpaper until they fit just right into the CDs' holes.
Be sure not to over cut. Cutting away the outside of the cork is a great way to save time from sanding, but don't over do it. Better too snug than too loose. When you get close to the right diameter for the cork pieces to fit into the holes of the CDs, test and sand and test again.
Once the corks are the right size, pierce them with small nails. These will form a "needle bearing" on which the entire contraption will spin. Try as hard as you can to get the nails to be perpendicular to the CD and as close as possible to the dead center or it. Otherwise, you'll get wobble.
Step 5: Attach the Magnets
Step 6: Glue Can to CDs
Also, try to follow those templates. The Savonius turbine requires that the two halves sort of over lap. This lets the air push on both "buckets" at once. Clever, huh?
Step 7: Tap in Dimples into the Paper-Towel Holder
- with a hammer, tap each end with a small blunt nail followed by a phillips head screwdriver
- don't make a hole, just a deep dent
- test the mechanical action with your turbine frequently
- add WD40
- adjust the height of the nails if there's not enough or too much pressure on the turbine (i.e. it keeps falling out or it's stuck and really slow)
Once satisfied, glue down the corks to the CD
Step 8: Wind the Coils
Here's how to go about it.
- use a dowel for the big spool of wire
- put bobbin on an awl, then insert the awl into variable speed drill
- leave 10 - 15 cm hanging when you start. You'll need these to make connections later.
- wind the first wrap slowly or by hand. If you're using thin stuff, do it by hand.
- you can increase speed thereafter. Again, be gentle if you have the thin wire.
- go back and forth, try not to cross, be neat.
- if using thin wire, be careful:
- in case of breakage, use a lighter to burn off the enamel that insulates the wire
- tie the pieces back together tightly
- it doesn't hurt to check the repaired connection with multimeter
- leave 10 - 15 cm on the outside, too
- burn off about 1 - 2 cm worth of the enamel and the end of each coil with a lighter (just be careful with thin stuff, since it will burn up really quickly--a quick pass with the flame should suffice). Use fine sandpaper to take off anything that stays on.
Step 9: Label the Coils
Follow the template if you're confused about this step.
P.S. (ignore the odd ordering of the "B" group in the photo. Just number them B1 through B4. I had the order the way you see it there because of a different--and less efficient--wiring method I had tried earlier. More on that later).
Step 10: Solder the Coils Together
Well, actually, here are some useful tips:
- solder flux helps a lot. You can use a lot less solder and with a lot less hassle.
- follow the diagram (bears repeating)
- do one group at a time. Start with A1 to A2, A2 to A3, A3 to A4, then go to the B group
- test the layout using the pattern provided.
- solder a thicker wire lead to the "1" end of each group. This will lead to the rectifier. More on that soon.
Step 11: Make a Base for the Coils
The most important thing is to try to get the coils to be as close to the magnets without collisions. If you can position the coils on the base so they sit just 1 mm below the spinning magnets (watch out for wobble) then you're in good shape. Also, try to make the base as stable as possible. At higher RPMs, the turbine can really start to rattle a bit, so keeping things together in those conditions is crucial.
Step 12: Layout coils
Check that the current all flows one way. That is, if you imagine an electron running through the coils, it always enters the coil from one particular side and exits from another. Just don't cross the wires over, and you should be fine. The arrows on template should help you think about how the electrons should be running through the coil wraps.
Now glue those coils down. Glue 'em down good.
Once that's set, solder the remaining three ends together (the ones not soldered to thick wire that should be sticking out of the "4" coils). This is the neutral point. In our circuit, you won't need to access this junction again, so you can tape it down or otherwise hide it under the coils' base, along with excess lengths of the other connections. In fact, the more you can do to tidy up stray wires, the better. A malfunctioning turbine that comes out of its divots has a nasty tendency to grab exposed wire and tear it up. Fun to watch, but hell to repair.
What you should have left are the three thicker wires connected to the "1" coils on each of the groups. This will lead into the AC to DC conversion circuit.
Step 13: A Brief Explanation
The benefit of doing it this way is that we can jam in some more coils than we would if we just did a simpler version that produced a simple AC wave. Also, this method allows us to get about 1.7 times more voltage out of the generator than the coil groups would produce on their own. That's the magic of this "Y" configuration: it gets us more voltage for low RPM generators, which is definitely what we have here.
There is another configuration worth mentioning (and it's the reason my "B" looked out of order in the photos). The "Delta" configuration gives us the same voltage as the individual coil groups but about 1.7 times the current. So, if you really needed more current, and you could get the turbine spinning fast enough to take care of your voltage needs, that might be the way to go. It wasn't for me, but feel free to research it for your own stuff and let me know how it works for you.
Step 14: Circuitry
That being said, start with a solderless bread board.
Either way, the big schottky diodes will need headers or wire soldered to them to fit in. They have leads that are too wide to go in. Regular diodes will fit fine, but they have a higher voltage drop. If you use the diodes I mentioned in the parts list, you lose less voltage with these big guys. Since every volt counts here, I'd highly recommend you deal with the added trouble of the oversize diodes.
When you put the circuit together, follow the rectifier diagram, watching the diode bands and capacitor polarity. Switching things the wrong way will make the circuit not work (or worse.) Attach a multimeter to leads off both ends of the cap and be ready to watch the voltage (start in millivolts for a reading, then work up as you spin it faster).
Attach coil leads by color per the diagram--they go between two diodes. The template should make this pretty clear.
Step 15: Test!
*apply more WD-40 if needed (note: a helpful commenter let me know that WD-40 is not a lubricant, but a solvent that has similiar properties--until it dries up. Use light weight oil instead, 5 to 10 weight)
*blowing on it will get you about .5 V DC with my set up. Hopefully you will get a lot more (it's those thin wire wraps that will do it for you)
*I had 1.12 volts with it sitting on a fairly gentle AC vent
*with the Shop Vac, it gets up to 6 V at least before it starts to rattle like crazy and pop out of the dimples. You will probably get even better results.
Step 16: Conclusion and a Plea For Help
- double up the magnets and coils. Put one set on the bottom and one on the top. Wire the DC output of each in serial and double the voltage. Hopefully.
- bigger, badder coils. Really see if you can up those wraps to a crazy degree. I think that's the key.
- take a look at the mintyboost USB charger (http://www.instructables.com/id/EGBQJPLCB2EP287KTZ/). I've spoken with the inventor herself, and she says that the circuit that drives it can work with input voltages between 1.5 and 4.5 volts, with the most efficiency in the middle of that range. It produces steady 5V power off of two AA batteries (which are only 2.4 to 3.0 volts). If you have this project with that one, do you get a wind-powered iPod charger? Try it and let me know.
- try a different bearing. My big thing is to use as simple and readily available parts as I possibly could, so I swore off fancier parts. You have no such limitation. I have it on good authority that skateboard bearings would be great for this. Or some other kind of bushing. Let me know what you come up with (especially if it's hacky, cheap, and better than what I've done.)
- Small lazy susans are available at art and sculpture supply stores that might also make good bearings.
- Made a bunch of these turbines? What happens when you wire them together in series? Can you make a "Pleech" farm?
- There's another more efficient Vertical Axis Wind Turbine design called the Darrieus Turbine (http://en.wikipedia.org/wiki/Darrieus_wind_turbine). It uses lift instead of drag. If you have an easy way to modify this turbine into one of those, drop a comment down here.