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

I wrap the 2 wires (blue and white) together, in the same way in the case of white ferrite and blue ferrite.

I connected the white wire of one side to the blue wire from the other side - this is the common end. Then I used the remaining wires to connect to the circuit as in the schematics.

I unwrapped and wrapped again starting opposite direction. I used grey ferrite core. I switched the ends. No way. Silent LED.

One moment I thought there is very low inductance in blue ferrite (for unknown reasons), so perhaps more winding would help.


The method is here (but it is detailed in many other web-sites)

https://www.evilmadscientist.com/2007/weekend-projects-with-bre-pettis-make-a-joule-thief/

and a more kids friendly desccription here:

http://technologytutor.co.nz/technology-and-science-for-kids/01-build-your-own-joule-thief

Show the picture

Here it is the pic:

  • background: the circuit which works ok
  • grey ferrite ring - which does not work (wired)
  • blue ferrite ring which does not work

The length of the wires in blue and grey cases were 80 cm and then 40 cm.

The length of the wires in the white ferrite ring 30 cm.

Add 1uF capacitor parallel to resistor

@Ted

Thank you for pointing me to the tutorial!

It is about a fixed H-rotor (giromill). Effective in high speed wind and the pitch can be modified automatically with the wind-speed. Some designs cant ensure starting on its own in low speed wind.

The person in the video used a direct coupling to the generator, which can be beneficial in terms of efficiency when winds are high-speed.

The interesting point is how the author shaped the wings to mimick an aerodynamic foil.

Can I use a 4.7 uF cap?

falexandru: Can I use a 4.7 uF cap?

ok

@ted - genial idea! Thank you very much!

My 4.7 uF cap got lost. So I use a 10 uF cap.

Mysteriously, the LED lighted! (she happy, me happy :-)). Using both the white ferrite ring and the blue ferrite ring.

With the cap, the white ferrite circuit seems to be less brightly than without the cap.

I didnt measure the current in both cases (with cap and without cap), so maybe is just an illusion.

+++

Ok with the classical and simple Joule thief, magnetic field etc. I can explain that, first to myself.

But I cant figure out what the cap does in this case. My first thought is that it changes the frequency to fit what the transistor can commute. But I maybe wrong.

Phase two: generator.

Firs fail: the toys motors cant supply the current I need to light the LED in the Jule thief circuitry I made.

I mounted a small propeller on a 3V motor and blow it by a hairdryer (a big one, really). Although the propeller spins very rapidly, like in the case of the motor being feed by energy, the LED did not light.

By multimeter to motor, the current supplied was up when the motor starts and stops - which I suppose has something to do with current pulse /induction.

I could not reproduce this behavior with the LED, however.

+++

Next attempt: PC fans. I shall check when I will find the fans I brought in my closet. :-((.

A more sophisticated attempt in plan: brushless motors. Using my dear Shotkeys to get DC. :-).

falexandru: But I cant figure out what the cap does in this case. My first thought is that it changes the frequency to fit what the transistor can commute. But I maybe wrong.

1k resistance for AC is reduced to ohms.

falexandru: Phase two: generator.

Firs fail: the toys motors cant supply the current I need to light the LED in the Jule thief circuitry I made.

Capacitor 10uF to motor terminals may help, why you not connecting LED directly to motor ?

I will mount a 10 uF to the motor.

Few months ago, a friend of mine mounted an white led to a PC fan. It lighted.

The wind turbine is part of the combined generator, that includes the PV charger (separate thread) and perhaps an energy harvesting module in a later stage.

Therefore, the wind, the Sun etc. will all charge the same battery. And the battery will supply current to the LED.

Modular design. :-)

falexandru:
I will mount a 10 uF to the motor.

Few months ago, a friend of mine mounted an white led to a PC fan. It lighted.

That is my question in post # 46.
If LED is not lighting reverse connection of it.
Basically any motor with magnet should work

I reversed the connections of the toy motor with no result. Maybe I shall check the wiring, connections again.

Ill check mounting the LED directly to the motor, to "debug" :-)).

The motor my friend used was a PC fan one, which is far lower rpm than a toys motor.

I randomly pick up a few motors and speed them quickly by hands, and the LED is always lighting, if is not I change rotation direction. Jule thief required pure DC, from motor you don't have that.

Then I have to make sure I get a pure DC from my generator.

Maybe using the same concept of Shotky + Zener as in the case of Photovoltaic charger? But the problem is now how to regulate 1 V, in absence of this value in the Zeners range.

And is also more problematic because the available power is much less than in the PV case, I dont like to throw current away.

I came across LT3022, which is manufactured by Analog, which is stated to regulate as low as few hunderd miliV. Looks interesting, although not in line with my "simple design" rule.

http://www.analog.com/en/products/power-management/ldo-linear-regulators/positive-linear-regulators/lt3022.html#product-overview

Another interesting idea is to use a supercapacitor. Then the motor will charge the supercap and the supercap will charge the battery via Joule thief- in order to reach the required voltage to charge the NiMH (or LiIon).

A nice point in this approach is that I can charge the capacitor during night and discharge it daytime. Or using 2 of them, each for 12 hours.

+++

I searched the internet about supercaps as chargers but no result so far.

I suppose no matter the voltage (usually 1-3 V, very variable), the cap will charge anyway. Then the problem is how to gradually discharge the supercap into the battery.

How about not to use Joule thief, battery will be charged without it ?

OP really needs to look at the physics of what they are trying to achieve. Small DC motors simply wont work for this kind of application as they are designed to spin really fast, usually in the thousands of RPM, and a vertical vane wind turbine will simply not spin this fast, no matter what. You will be lucky to get a few hundred RPM from one . Small wind turbines use a special type of alternator, usually a 3 phase permanent magnet type with very strong Niobium magnets to get a sufficiently high magnetic field to allow the turbine to produce usable voltages at low RPM. Do some research on small vertical vane wind turbines and the types of generators they use.

Motor like this gives 2.5V @ 500 rpm ( speed of my drill)