Is joule thief circuit gets overunity?

[MileHigh]

Fausto:

The inductor takes more energy to store the energy as magnetic field? Extra energy? if the inductor has for example 10 ohms resistance, how can it really take more energy than a regular resistor?

Not extra energy.  When you first put voltage across an inductor no current flows.  Electrical work has to be done to get the current to flow through an inductor (voltage x current x time).  The current starts from zero amperes and slowly climbs.  Once the current is flowing and you put a high resistance load across the inductor then you get a back-EMF spike.  The energy in the back-EMF spike is identical to the work (voltage x current x time) that was expended by the battery to get the current flowing in the first place.

This is in contrast to a resistor where the current starts to flow the instant you put voltage across the resistor.  There is no "extra work" required to get the current to start flowing through the resistor.  Likewise, there is no back-EMF spike from a resistor.

Bill:

If resonance is not a factor in these circuits then why is it when I run a basic JT circuit from say a 10 F cap, and use a vr as the base resistor, I can add resistance and the lights get brighter and brighter and then, they will start getting dimmer as I pass "the sweet spot".  This is a very delicate adjustment to get it just right.  Any change in the circuit, even one winding, will make this resistance incorrect again and it must be retuned.  You are saying that this tuning does not hit a resonance node?  If it is not a type of resonance, then what is it that allows this tuning to achieve some very dramatic results when hitting the sweet spot?

The "sweet spot" in the example you described is not related to resonance.  As you vary the base resistor the oscillator part of the JT is changing its performance characteristics.  You tune the base resistor in such a way that you have the coil switched on for a longer time and it's also possible that the switch-off of the transistor is "snappier."  The longer the coil is being energized the more current will be flowing through it when the transistor switches off.  The faster the transistor switches off the less energy will be wasted burning off through the switching-off transistor and the more energy will be passed to the string of LEDs.  So you get maximum brightness with your string of LEDs if you have maximum current flowing through the coil and the fastest switch off of the transistor.  In simple terms you were tweaking your oscillator circuit so that you were maximizing the amount of energy per pulse that was being transferred into the array of LEDs.  So tweaking in this case is not related to resonance at all.

This is where an oscilloscope is king.  What you want to do is make a timing diagram and with the aid of your oscilloscope draw up a timing diagram with all of the relevant voltages and currents that show the JT oscillator in action.  If you want to truly understand the circuit and how changing the value of one component affects the operation of the JT, then you want to understand exactly what each waveform represents and the interrelationship between waveforms.  It's not as challenging as it may sound.  For example, you see the voltage go high at the base resistor, and as a result you might see the voltage at the transistor collector going low because the transistor is switching on, etc.

The fundamental and most important two parameters for any JT circuit are the inductance value for the main coil, and the amount of current flowing through the main coil when the transistor switches off.  That determines the initial current flow and how much energy will be transferred into the LED or LEDs that typically form the load component in the JT circuit.  And of course that determines the brightness of the string of LEDs.

MileHigh

[TinselKoala]

first, thank you for answering my question. The inductor takes more energy to store the energy as magnetic field? Extra energy? if the inductor has for example 10 ohms resistance, how can it really take more energy than a regular resistor?


Fausto.

Let me jump in with an analogy. Think of electric current as the flow of water in a hose. A resistor, then, is just a simple restriction in the hose: it decreases the flow but the outflow happens immediately that you provide some inflow. An inductor is like a balloon or soft spot in the hose. You apply pressure at one end, and before anything comes out the other end, the balloon must swell up first. Then once it's swelled up... storing energy in the tension in the skin.... then output starts to flow, but it's the same current as the input. When you turn off the input, the balloon collapses continuing the outflow for a while and releasing the energy you stored in the stretched skin.
In an inductor the magnetic field is like the balloon. So there is a slight delay when you turn on an inductor as the field builds, and there is a slight delay.. .the current tries to keep flowing....  as the field collapses when you turn the inductor off.
The resistor takes extra energy to push current through it but this extra energy is lost: dissipated as heat. The inductor returns the energy it took to set up the field back to the circuit, it's not wasted.

[TinselKoala]

YES.  Thank you for your enlightenment.  I redid the experiments using DC coupling.  I can now specifically pick out situations where COP is greater than 1 with DC coupling setting on my oscilloscope at home.
There will be more experiments and many researchers double and triple checking the results.  Once that is done and confirmed, I shall publish the results.
The new technique makes resonance hunting and extracting electron motion energy a piece of cake.  The commercial interests may try to stop its publication.  The latest date for this information to become public is Oct 2013.
All Glory and Praise to the Almighty.

OK. You are welcome.... but just to be sure that you are really enlightened, can you please repeat back to me your new understanding of the use of AC and DC coupling on the scope, and why and under what circumstances each is to be used?. By restating it in your own words we can check to see if your enlightenment is real, or an illusion.

ETA: Also, can your scope do math., specifically trace multiplication and integration, and can it store traces in memory?

[ltseung888]

OK. You are welcome.... but just to be sure that you are really enlightened, can you please repeat back to me your new understanding of the use of AC and DC coupling on the scope, and why and under what circumstances each is to be used?. By restating it in your own words we can check to see if your enlightenment is real, or an illusion.

ETA: Also, can your scope do math., specifically trace multiplication and integration, and can it store traces in memory?

The Atten scope can store data from the two channels simultaneously as CSV files.  I can then use Excel to analyze the data as you have seen from the file.  This relatively cheap scope (<US$200) bought at ShenZhen is an excellent value for money instrument.  I believe PhysicsProf got one too.

I am interested in the formula that is correct in Physics:
Instantaneous Power = Instantaneous Voltage x Instantaneous Current.
That formula holds whether the system is DC, AC or Pulsed.

I initially did not use the oscilloscope and rely on Voltage Reading at no load to compare the various FLEETs.
I then put all measurements with AC coupling.  That gave high Output/Input ratio (False COP?).  Some FLEET with high ratios could light up many more LEDs for longer periods.  I used that ratio as a comparison index to determine which FLEET might be better.

I have now taken your advice.  I repeated many experiments with DC coupling.  Some low ratio FLEETs no longer show ratio greater than 1.  However, some FLEETs with high ratio in specific conditions still show COP >1.  The Average Output Power can still be negative.  It really narrowed down the search for resonance-tuned devices that show commercial value.

Thank you for your advice.  Now resonance tuning and getting commercial resonance conditions is a piece of cake.  I already achieved two situations in the last few days.  (The first commercial resonance condition took me eight years and G-LED found it. Not me.)  When there is lead-out or bring-in energy, having Output power greater than Supplied Input Power does not violate any Laws in Physics and has been achieved by many (who may not even know or know how to confirm it!)
*** The use of Vpp or AC coupling as comparison index was useful - even now.  The high index FLEETs work better!  So one can be wrong in the exact understanding but right in the general direction!

God Bless.

[MileHigh]

TK:

Let me jump in with an analogy. Think of electric current as the flow of water in a hose. A resistor, then, is just a simple restriction in the hose: it decreases the flow but the outflow happens immediately that you provide some inflow. An inductor is like a balloon or soft spot in the hose. You apply pressure at one end, and before anything comes out the other end, the balloon must swell up first. Then once it's swelled up... storing energy in the tension in the skin.... then output starts to flow, but it's the same current as the input. When you turn off the input, the balloon collapses continuing the outflow for a while and releasing the energy you stored in the stretched skin.
In an inductor the magnetic field is like the balloon. So there is a slight delay when you turn on an inductor as the field builds, and there is a slight delay.. .the current tries to keep flowing....  as the field collapses when you turn the inductor off.

I am not a fan of your analogy because the current going in one end of an inductor is equal to the current going out the other end of an inductor.  With your analogy that's not the case.  In your analogy, the "balloon" is more akin to a capacitor connected to ground before the resistor.  Then the KCL works.

But let me modify your analogy and keep with the garden hose idea.

You have a straight 10-foot length of garden hose with a restriction at the end of the hose.  That's equivalent to a wire connected to a resistor.

Now, suppose at the 5-foot point along the hose you have a hose coupling.  You open up the coupling and you add a coiled 50-foot length of hose.

Now the setup is as follows:  A 5-foot length of hose, connected to a coiled 50-foot length of hose, connected to a 5-foot length of hose with a restriction at the end of the hose.

The coiled 50-foot length of hose is the inductor.  There is a lot of "extra" water inside the 50-foot length of hose and it has mass and momentum.   You have to do "extra work" to overcome the inertia of all of that extra water to get the water flowing.   If you block the end of the hose, you will get a big surge in water pressure.  That's the back-EMF spike.

You note in this analogy KCL is respected and works.

MileHigh