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Micro-VAWT Experimentation

Posted by admin on Aug 2nd, 2010
Aug 2

I’ve been starting to experiment with micro-wind turbines lately and have been trying to think of turbines that are complact and not very noticable. This is mainly for my wife’s sake, as she wasn’t exactly fond of my last attempt at a VAWT. I’m also trying to keep the cost as low as possible by reusing items that are on their way out to the landfill or recyling plant – things like paper towel rolls, old cd’s, cardboard, etc. We’ll call it a prototype development phase. There are so many things to consider when attempting to engineer these micro-power plants, things like motor size, regulation, “blade” size, etc. That’s why using items from the trash to experiment with is a great prototype method. Right now I’m focusing on the VAWT template because it’s very appealing to me, since I live in an apartment and would have a much easier time getting away with putting up a VAWT compared with a traditionally bladed turbine.

I have a used computer fan that I’m using as my base generator. It’s got minimal output potential – 12v and about 0.12A, or about 1.5 watts. It’s a good test bed though as it doesn’t take a whole lot to turn it, so I can focus a little more on design first rather than just coming up with something that will actually turn the motor. It may seem a little backwards, admittedly, but in my attempts in the past I was unable to successfully build an efficent VAWT that would turn itself very well, let alone a motor at the speed needed.

I initially created a VAWT using a tp roll, but it was way too small. I then turned to an empty oatmeal container. This is showing to have a lot more promise due to sheer size, but it is way bigger than the motor so it’s not as efficient as I would hope. Below is a picture. I put it all together using paperclips, an old cd, cardboard under the cd to raise it up a bit, and double sided tape to secure the base to the motor. I’m still going to do more experiments with it and try some other configurations, but fornow this is where I’m at.

3 Responses

  1. Andrew Says:

    If you want a hefty current capable “generator”, in keeping with the big spender components…

    1. locate an old printer. (The older the better)

    2. Remove the servo motor(s).

    3. Remove the power supply – if you want to scrounge out the parts… (optional)

    4. Look up the servo spec s to verify the leads for the “pairs”

    (Some servos will have 4 leads/contacts for 2 pairs, though some have 6/3. Use an LED to find the pairs that push out current when you twist the spindle)

    5. Set up a bridge rectifier to convert the ouput from all pairs to a single DC output.

    6. Try using the belt from the printer to connect the wind turbine shaft to the servo.

    7. You may have to step down the rpms to the servo – watch the output voltage – don’t let it get too high, or too hot.

    Unless you keep the rpms low enough to avoid overheating, the servo won’t last too long. In any case, this will never be a setup that can be expected to last very long, because of the lack of any real bearings in the servo designs for these low end printers.

    On the upside, Such servos are basically free when you can scrounge them, and turn out a surprising amount of current at low rpms.

    I would be tempted to leave your experimental rig on the CD platter for basic support, but I would add a second CD motor at the top, to allow for a stronger 2-point mount.

    If you put some sort of dowel, or copper/ABS pipe between the CD base, and the scoops, then you could run a belt around the pipe/dowel, to connect to any sort of generator — quietly. Changing the dowel, or adding a pully would allow you to adapt your rotation speed to drive the generator at a desireable voltage.

    For longer term use, I recommend a scope to examine the input to any charging circuitry you want to use. The servos can really pack a punch, and a small filter might allow your batteries to last longer. A scope would help you see this.

    Let me know how if you have any problems…


  2. admin Says:

    Hey Andrew-

    Thanks for the comment, and all of the great info! I will definitely try some of those suggestions out. I have an electronics “junk yard” close by my house that will probably have some old printers laying around – or at least motors from them. I am hoping to find time to work on this project again, but the holidays, work, work travel, etc – it’s just been impossible to find time for these things lately.

  3. Louie Says:

    Great project! How did it go? Did you try any new designs and got some interesting experiences?

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