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Topic: Wind turbine Savonious Charger based on Joule Thief - advise for a charger? (Read 4136 times) previous topic - next topic

polymorph

Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

ReverseEMF

FYI: I've used the following to make Joule Thiefs -- but they are SMD parts, so may be hard to solder too.  Perhaps you can make a breakout board for one, or both of these:

https://www.mouser.com/ProductDetail/704-DRQ73-330-R
https://www.mouser.com/ProductDetail/652-SRF0703-330M
"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

Under controlled voltage (bench supply source):

Small  13x7x5 mm ferite ring: starts lighting at:
- without capacitor: - 0.85 V
- With capacitor 10 uF : 0,83 V
- Adding 47 uF to existing 10 uf, in parallel  -> the led dimmed and started blinking!

With the capacitor, at the same value of voltage, the LED is brighter.

The source displayed current of 0 - 0,002 A, changing every second.





Certainly, the capacitor helps by lowering the supplied voltage to which the LED opens and to providing more current.

There is also a clear link between the capacitance, the inductance and the rise in the voltage to the LED pins.

Because the values of the parameters are close to the source and multimeter accuracy, I cant fine tune the voltage - in the range of 0.001 V.

The practical consequence of these findings is that there is a value of the capacitor that grants best efficiency of the circuit. But how to calculate?

falexandru

@polymorph

It is nice to have a plan B, thank you!

@ReverseEMF

Thanks for pointing me to the commercial names and look of the coupled inductances!

My attempts to find them here were not successful do far, because of vendors having no idea from my description what I was looking for :-(.

falexandru

A.

Changing the ferrite ring by a larger one - 20 mm diameter:

- using 47 uF the LED is brighter than using 10 uF.
- The voltage from which the LED started to light was 0.82 V, while the current was stable at 0.002A (sources shows).

I guess I can confirm then that the value of the capacitor that makes the circuit able to light the white LED is in close relation with the value of the ferrite inductance.

I also believe (but I have no evidence) that some circuits still rise the voltage without a capacitor because the (implicit) capacitance of the circuit is enough to keep the oscillations, at lower values of inductance.

B.

I mounted both ferrite rings (the 13 mm one and the 20 mm one) in parrallel, with the 47 uF capacitor on. The LED started to light at 2.15 V.

For the time being I cant measure the inductance and the vendor has no clue about DS of the ferite rings :-(.

C.
Late edit: once the circuit is on and the LED lights, at about 0.85 V, then decreasing the voltage to 0.56 dims the LED but it still brights.

D.
Later edit: the 1 uF capacitor turns the LED on from 0.56 V (as the source displays).

falexandru

I opened another thread that combines this one and the one related to solar charger, because these two will work together. 

The discussion may continue in that combined thread, in the same section (General Electronics) of the forums.

Thank you!

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