Joule Thief

[jadaro2600]

...
In a well-designed induction coil the energy in the secondary, i.e., the induced current, is for all practical purposes equal to that of the primary current, yet the values of the voltage and the amperage of the induced current may vary widely from the values of the voltage and the amperage of the primary current.

...I think what you have highlighted here is an emphasis on what the main passage suggests - that someone can vary the number of turns and thus, vary the voltage and current widely.

Not that varying one will incidentally cause wide ranges of either without bound or reason, ...that is to say.

And you would get less ( as it stands, a moot point indeed, that is ) that if electricity flows through even a small portion of conductor it looses something, the degree of measurability is thrown into question, which is why we put up with tolerances, throw fixes into the design, and move on.  The inductor is actually a fix for some problem in circuit design, and a kink in yet another - each part will ultimately have it's place.

Having a perfect transformer is almost an absurd thought - not that there haven't been absurd ( working ) thoughts before.

[gadgetmall]

I found this so i thought i would post it here. i hope this may help out

THE TRANSFORMER
The secret of this circuit is the transformer.
We normally think of a transformer as a device with an input and output, with the voltage on the input and output being connected by a term called "turns ratio."
If the output has more turns than the input, the output voltage will be higher.  This is called a setup
transformer. If the output has less turns than the input, the output voltage will be lower.
This applies to "normal" transformers where the voltage is rising and falling at a regular rate, commonly called a "sinewave."

But the transformer in this circuit is different.
The voltage applied to it is not rising and falling smoothly, and thus it does not work in normal "transformer mode."
The voltage is being applied and then turned off. When the voltage is applied, the primary winding (the 90 turn winding) produces magnetic flux. When the voltage is turned off, the magnetic flux collapses and produces a VERY HIGH voltage (in the REVERSE DIRECTION), in all the windings.
Our transformer is really a coil in flyback mode with a feedback winding.
The feedback winding delivers a voltage to the transistor to turn it on HARDER. If the winding is connected around the wrong way, the circuit will not work.

The other important factor about the transformer is the core material. There are many different types of
ferrite. Ferrite is a type of iron which is powdered very finely so that the magnetic lines that pass through the particles do not create eddy-currents. These eddy currents absorb the magnetic flux.
The circuit also employs a term called RE-GENERATION. This is the effect where a circuit is turned on slightly by a component (the base resistor in this example) and then the transistor turns itself on more and more until it is fully turned on. The feedback winding is configured so that the voltage it produces (actually the current it produces) is fed into the base to turn the transistor on. Thus the feedback winding is very clever. It produces energy and is delivered in a particular direction - in
other words it can be a positive or negative energy. In this case it produces positive energy, to turn the
transistor on harder.
This is called POSITIVE FEEDBACK as it turns the transistor ON during the active part of the cycle.
Now we come to the MAIN, PRIMARY or FLYBACK winding. This winding produces a high voltage during part of the cycle (the FLYBACK part of the cycle) and this is passed to the LED.
If the LED is removed, the transformer produces a high voltage with a low current, but when the LED is
inserted, an amazing thing happens. The energy from the transformer is converted to a lower voltage with a higher current. What actually happens is the LED absorbs the energy and turns it to light as soon as the voltage rises to 3.6v. We could achieve the same low-voltage, high current requirement, with less turns, but the number of turns has to be determined so the core does not saturate.
The voltage for the LED is produced when the transistor is switched off and the magnetic flux in the ferrite core collapses. The speed of the collapse produces a very high voltage in the OPPOSITE DIRECTION and that's why a positive voltage emerges from the end connected to the LED. These two facts are important to remember. The other important fact is called "transformer action." This is the action of magnetic flux. When a voltage is applied to a winding of a transformer or a coil of wire, a current will flow and this will produce magnetic flux. If another winding is present, the magnetic flux will cut the turns of this extra coil and produce a voltage in it. However, there is a very important point to remember. The magnetic flux can be: EXPANDING, STATIONARY or CONTRACTING.
When the magnetic flux is expanding, a voltage will appear in the second winding mentioned above.
When the magnetic flux is stationary, NO VOLTAGE will appear in the second winding.
When the magnetic flux is contracting a voltage will appear in the second winding with REVERSE
POLARITY. The size (the amplitude or "value") of the reverse voltage will depend on the speed of the collapsing magnetic flux. If the flux collapses quickly, the amplitude will be very high.
That's how the transistor turns itself on and on until it is fully turned on. At this point the current flowing through the circuit is a maximum but the flux is not expanding so the base of the transistor does not see the high "turn-on" energy and thus the transistor suddenly turns off.
The magnetic flux collapses and the transistor sees a reverse voltage on the base to keep it turned off until the flux is fully collapsed. The current through the resistor enters the base to start the cycle again.
From this you will be able to see how the transistor and transformer work.

Hi Pardon . Nice Drawing . It looks Very similar to the one i made 300 or so post back The Vr  / cap adjust the Bias of the base and creates a resonate tank . Mine is 100centertapped   x 30 secondary  running 4 leds at .81 ma total  or .20 ma per led .   I still have this circuit running now for 3 months . i added one of my 5 volt glass solar cells to it and just a wee bit of light a day keeps it running strong ! Notice How Jeanna secondary works wonders 

Gadget

[gadgetmall]

@ Xee2 and Gadget,

ho ho ho, do I smell a competition or a challenge between you both, the first to get 100 LED's lit from the lowest voltage possible, in time for christmas?, nothing like a competition challenge to hone the electronic skills. Whats the prize?  Wink

Lets make this interresting.
Now, do they have to be turned on all the time, or can they be made to work by being turned on and off so fast that the eye cannot see it happenning, or is there a limit of time they have to be lit, anything from 1 second, or 1 miinute or 10minutes or, for 1 hour.

@Gadget,
I'm having a field day, Bought my usual Silicon Chip magazine, inside for free was the Jaycar catalog, drool drool drool.
Christmas wish list time again lol

Hy Jim . I know what you mean about catalog wishin . I spend days looking over each item and what i will do with it  . heheheh,  > I wonder if Dick Smith still sends out Flyer's . They used to have some cool stuff. I know one thing they got  that is Unique(Thanks) BTW . I got a little something going your way . I will just let it be another surprise . I am doing well in the kit biz (Thank you all for supporting Asia and I ) and its time ..
yes sound like a nice side project to light up 100 . I already am lighting 20 now with less than .. well lest see i won't spoil it buy stating My ma draw but it beats My old record by a factor of X .

the Prize .  Christmas ... . Hmmm . .I'll donate somthing ..

L8r

Gadgetmall

[Mk1]

@all

Logic Circuit for toroid!


http://www.google.com/patents?id=dmZVAAAAEBAJ&pg=PA1&dq=toroidal+power+inductor+unit&source=gbs_selected_pages&cad=0_1

[jadaro2600]

@all

Logic Circuit for toroid!


http://www.google.com/patents?id=dmZVAAAAEBAJ&pg=PA1&dq=toroidal+power+inductor+unit&source=gbs_selected_pages&cad=0_1

...if every patent were written so that an idiot could understand the device, then the world would be a much better place.  The last few dozen patents were written as such, the more recent they are, the harder they are to understand.