Wind turbine Savonious Charger based on Joule Thief - advise for a charger?

falexandru:
I thought is much better to leave the image in the attachment. :-(. Reason is to have only a small number of scrolling down moves, based on the psihology of the number of clicks. Having everything in one screen only allow eyes to "scroll", instead of hands + short term memory.

Here's the drill:

  • Attach image
  • Post
  • Find attachment in post, right click it, and find "Copy link address".
  • Re-open post using "Modify" [find: "Quote ~ Quick Edit More" -- click on the little down pointing arrow, then click "Modify"]
  • Use the Image Embedding Tool to embed the image in your post [using the URL you copied in step 3].

That way, blokes like me, have an option to "scroll", or "download" [since the attachment remains, even after embedding the image]. Providing that option incurs no more deficit than a little more work for you, and a little less for the kind folks that attempt to assist you.

And I fixed that link -- so, if my terse explanation didn't do it, then try the link [again] -- also, you could have Googled it -- I mean if you were really determined :wink:

I dug this out of my archives. This is a version of the Joule Thief that I came up with a while back, and I think I even got it working. It's a bit more efficient:

Notes:

  • D1 is something like a 1N5817.
  • Q1 could be a 2N2222A, but something like a 2N3904 might work better.
  • C1 is like your 4.7µF cap -- which you wanted to put in place of that 0.01µF cap [in the diagram you supplied], which will, likely, not work -- especially for the purpose you proposed.
  • You said you want to use this as a "charger". I'll assume you mean a "battery charger", in which case, you plan to replace the capacitor [the one after the Schottky diode], with a battery of some sort, right? That may work with some battery chemistries, and not others. Huge subject--one that I'm not fully versed on.

And, here's your diagram, again:

I'm not sure what you're trying to achieve with that Zener on the Base of the transistor. The forward voltage drop across the Base-Emitter, will never allow that voltage to rise any higher than around 0.7V, so the Zener will have no effect, unless it's to protect the transistor from reverse voltages, and I've never seen the need.

1 Like

Hi,
How much POWER are you going to get out of your Savonius (vertical axis) wind turbine?
Can you post its specs/data, and/or a picture please.

For flea power systems the Joule Thief works well, you may have to check how reliably it starts with slow power level changes.
The Joule Thief is basically an oscillator, so to start, it may need a proper step ON to reliably function.
You will need to experiment to check it suitability.

Interesting project.

Tom... :slight_smile:

For the Savonius I only have a concept at this time. Plan is to make a 4 wings one (to balance), for some 1 m high.

How to transmit force from the rotor to the generator - still to be decided.

One plan is to directly glue the generator's axis to the turbine axis. Another plan is to use friction wheels. The point in any transmision is that I will loose power no matter what. But I need some velocity to milk the rotor, which I suspect will be difficult ot obtain directly from the Savonius rotor.

++++

Initially, I wanted to use PC fans and replace the wings by some longer profiles. When I went to the field, I found out there is very slow wind (forested area). Most likely, a propeller turbine would have no enough wind to move.

This is a demo project. It is to prove that wind can generate electricity and to show how it works. Efficiency or economic aspects are not important, for the time being.

During internet search I came across various other Joule thief circuits. But the main problem for all is that there is very little info (if any) of whether those circuits were ever moved from the screen to the real life. I do not know whether they work or not.

As a result, I made my mind to make it as simple as possible, and therefore I picked the circuits with less components. One of them is the one I posted, but I do have a few more (main criteria are: not to use more than 2 transistors and no integrated circuit or modules).

It is to prove that wind can generate electricity and to show how it works

Is there someone on this planet, above the age of 5, that doesn't already know this?

@ jremington

Try to explain how wind can generate electricity to a 12 years old kid.

Or just answer to yourself: why planes fly?

jremington:
Is there someone on this planet, above the age of 5, that doesn't already know this?

Have you never heard of a Science Fair project [for example]?

Here it is a even simpler Joule Thief circuit.

The point in the charger I try to build is to get voltage above 4.5 V to charge my 3 NiMH units.

And to do this out a Savonius that can offer the most - 3 V (in happy situations).

Using only few components and no module.

The challenge it to have it working.

:-).

https://forum.arduino.cc/Themes/default/images/post/clip.png![](https://forum.arduino.cc/Themes/default/images/post/clip.png)

https://forum.arduino.cc/Themes/default/images/post/clip.png![](https://forum.arduino.cc/Themes/default/images/post/clip.png)

The image does not show up. I inserted the link to the URL of the image - nothing. I have no idea what to do then. :-(((((

falexandru:
The image does not show up. I inserted the link to the URL of the image - nothing. I have no idea what to do then. :-(((((

To the following thread:

http://forum.arduino.cc/index.php?topic=364156.msg3749026#msg3749026

I added a more comprehensive tutorial than any other I could find on that thread. Have a look at it [Post #74]. Hopefully that will help you understand how this is done :wink:

"This site can’t be reached
%22’s server IP address could not be found."

When I go to the "insert image" the only window I see is the one for the URL. Nothing else.

I am on Windows7 64b.

falexandru:
"This site can’t be reached
%22’s server IP address could not be found."

When I go to the "insert image" the only window I see is the one for the URL. Nothing else.

I am on Windows7 64b.

Yup. I caught that, but obviously not quick enough :wink: Try the link again, it should be working, now.

I am trying again.

I have no idea why it did not work first time. Just do not understand.

For the Savonius I only have a concept at this time.

The most important device here is likely to be the generator. Using an off-the shelf cheap dc motor is unlikely to be the best solution.

Consider winding your own pm alternator?

Until you know what your generator produces, discussion of various possible power conditioning techniques is academic at best.

Alan

Have you actually built the wind turbine ?
Savonius rotors are very inefficient, and if you are trying to generate anything at very low wind speeds, the type of generator is most important, as it requires extremely low rotational friction.
Id start by building the turbine first, and then worry about getting useful power from it.

This is a demo project.

Any little power is sufficient.

If nothing else works, then I will use a fan to move the Savonius rotor (I must do this indoor anyway). Or even blowing on it. :-)).

Note about my post #17: Uploading the picture to show up within the text did not work first time.

I did not experiment the posted circuit in post #17.

falexandru:
Note about my post #17: Uploading the picture to show up within the text did not work first time.

I did not experiment the posted circuit in post #17.

Do you mean post #18? If you are referring to the diagram in that post, it's the "classic" Joule Thief circuit. It's pretty easy to get that working. But, it's critical to get the coil hooked up correctly. I suggest adding a capacitor across the generator [following the power switch]. The value will depend on what kind of power is involved. Such a capacitor will make it more likely that charge will accumulate and run the stored voltage up until the Joule Thief starts to oscillate. Then, it will transfer power from the capacitor, to the battery. But, as pointed out before, this will only be feasible for a low power system. But, it sounds like that's what you are after -- merely a demonstration of principle.

@reversEMF - right!

I only want to show that this way of obtaining energy is feasible using basic resources, it is easy to make, easy to maintain.

[maybe OT: so many times I saw projects (including my projects :-)) never getting to an end because of to ambitious goals. It is crystal clear in my mind that Arduino is about learning and teaching in the first place. Of course, real life projects can be done in the Arduino ecosystem (or alike), but myself I am not in this.]

Thank you for the reccomandation! It is possible to use a trimer (aka variable capacitor) for the capacitor you suggested? If so, what value do you think?

I can find here easy a 4-20 pF and a 7-100 pF.

The 7-100 pF has a larger range so might be handy. Then I can go (hopefully :slight_smile: ) by trial and error.

The coil- yeah, I have a bunch of torroids and drossels on my desk. I cant measure them by my multimeters and honestly the devices to measure capacitance and inductance are insanely expensive.

Please the "Quote" feature. Otherwise, it's hard to track context when reading your posts.