Go Down

Topic: Wind turbine Savonious Charger based on Joule Thief - advise for a charger? (Read 4476 times) previous topic - next topic

falexandru

I am working on a very simple charger based on a Savonius (vertical axis) wind turbine charger.

The basic principle is the same as in my previous project using a solar panel to charge 3 NiMh AAA batteries.

The difference comes from:
a) the Savonius rotor offers much lower voltage than a solar panel (namely 1-3 V); reason to use it instead of an horizontal axis (propeller) is it start offering power from lower wind speed
 
b) the out put voltage is much more variable as a result of very variable wind speed

I avoid the dedicated push up power modules as being very hidden in terms off explanation.

So I plan to use a modified Joule thief circuit.

The compont's list (modified from the internet source) is the following:


NPN Transistor - one I can find in my shelves (original: 2N2222, 2N3904, or similar)

4.7 uF capacitor (the scheme provides for a 0.01 microfarad Capacitor) - I made this modification to allow more energy to get stored when the wind blows instantely

330 microfarad Capacitor

470 Ohm resistor( instead of the original 1 kohm resistor) - I made this modification to reflect lower voltage selected (4,7 V instead of 6 V in the original design)

4.7 V Zener Diode

Shotky Diode (instead of a regular diode in teh original design)

Perf Board

1 toy electric motor 3-6 V.

various PVC profiles, screws.

The original design (which includes a common diode and a 6 V diode) is here:

http://www.instructables.com/id/Joule-Thief-Low-Voltage-Battery-Charger/

I clipped the schematics from this web-site is attached.

The modified by myself circuit is to charge a series of 3 AAA NiMH Batteries 800 mAh (the same as in my previous solar charger) which at its turn will light an white LED  (the same as in the previous solar charger).

Is somebody please more familiar with the Joule thief circuits to be so kind to give me an opinion about whether this modified circuit may work? Thank you very much!

falexandru

I found this explanation about the "Joule thief" based convertors:
https://www.youtube.com/watch?v=wJU7AJgERG8

Far more complicated then I want, but I found it useful anyway.

+++

From the internet, these circuits can "extract" energy from an exhausted 1.5 alkaline pile. Although I could not find the minimum voltage of such circuits to work as input, I guess it is as low as 1V, based on the values of voltage in piles that cant be used anymore.

ReverseEMF

Gosh, it would be so nice if seasoned posters, such as yourself [OP], would embed your images in the text, rather than just attaching them, thus relieving those of us, who are want to apply our precious time to your cause, of the burden of downloading the flippin' thing ourselves!  If you don't know how:

http://forum.arduino.cc/index.php?topic=364156.msg2510120#msg2510120

But, in the wake of this lack of this, permit me:

"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

ReverseEMF

From the internet, these circuits can "extract" energy from an exhausted 1.5 alkaline pile. Although I could not find the minimum voltage of such circuits to work as input, I guess it is as low as 1V, based on the values of voltage in piles that cant be used anymore.
I've seen them function all the way down to 0.5V -- that during a continuous run.  It takes a higher voltage to start the thing -- ~0.8V, but it varies.
"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

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.

But well, I will try do do it from now on, since people feel more confortable with this "on screen" method.

Anyway, I cant figure out how to enable the image in the text. If I want to insert a pic, the interface asks me for the URL. 

The link you posted does not work. :-(

ReverseEMF

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 ;)
"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

ReverseEMF

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.
"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

TomGeorge

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... :)
Everything runs on smoke, let the smoke out, it stops running....

falexandru

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).

jremington

Quote
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?

falexandru

@ jremington

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

Or just answer to yourself: why planes fly?



ReverseEMF

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]?
"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

falexandru

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

falexandru

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. :-(((((

ReverseEMF

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 ;)
"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

Go Up