Joule Thief 101

[Magluvin]

The battery is down but not dead dead. 1.2v

Mags

[sm0ky2]

@MH

it is obvious by the waveforms you keep presenting, that you have not paid attention to a single thing I posted over the past few days.
None of these waveforms are either in resonance nor in the linear mode of operation of the transistor.

You can continue to show NON resonant JT circuits in operation, and proclaim my analysis of the circuit to be invalid.
yet, in doing so, you negate the prerequisites that are placed on said resonance.

thus, your actions are similar to that of a Diver, proclaiming that because of the Human Physiology, man can only hold his breath under water for roughly 4-5 minutes.
When the reality of the situation is that Pearl Divers in Indonesia use a technique known as "static apnea" to hold their breath for 15-20 minutes.

Yet, here you are, stating that Static Apnea is not a relevant factor, and that it cannot help you hold your breath longer.

This is exactly what you are doing with resonance, as it pertains to the Joule Thief.
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Your reasons for doing so (although irrelevant) seem to indicate one of two scenerios.
either 1) You acknowldege the facts i have presented in the last few pages, and still insist in refuting them insensibly.
or
2) (which it sounds like you have admited at least twice) You do not understand that which you are discussing.
    and as such, your arguments are insensible, and do not apply to the actual reality of the circuit.

The videos which you linked are created and described by individuals that are not using the circuit in resonance,
nor are they accurately describing that which they observe. this is evident by use of the equations i have previously posted.
Had these individuals compared their speculative analysis to the electrical engineering mathematics of the circuit,
They themselves would have seen the err in their description of the circuits behavior.

It is good practice to limit your variables, when performing an experiment.
But one must be certain that altering these variable values, they are not changing other conditions of the system.
And if they ARE - this should be taken into consideration.

This was not done in the experiments you have posted.

I have met 3 of your four requirements of me, in my previous posts.
Since you claim that I have NOT, this to me means that you didn't really read what I posted or followed the links to the information provided.

the 4th requirement, you yourself have violated, stating that resistance is not an important factor.
Whereas, I have appropriately described every portion of this circuit (including the feedback loop which was not even my original intention).

To "show you" a JT in resonance, is pointless. You can tell by the waveforms that have been posted by other users, which ones are operating either in linear mode (by the sinosoidality of the waveform) and in resonance (by comparison of the peak amplitudes) or both.

If I were to show you any random variation of the Joule Thief, operating in linear mode, and at a frequency node coherent ot the SRF of the components involved, This scope shot would only apply to that particular JT circuit.
By adjusting the base resistor to bring the circuit out of resonance, and showing a scope image of the same circuit operating
"less efficiently", this woulod prove nothing to you. would it?
My guess is that you would still find some illogical argument to place on the images presented.

At this point in time, I am not certain of your intentions.

If you don't understand, then let it be.

If you DO understand, and not agree - then present that in a logical coherent manner.

If you don't understand, but still do not agree, then state that.
But do not pretend your knowledge set to be the end all say all.

You have already admitted to not fully grasping all of the concepts I have presented.
So why then, do you insist that your perspective is somehow more accurate than what I have shown here?

I will cease discussion on this point for some time, to allow the experimenters to absorb the information I have presented.
Their results will manifest themselves accordingly.

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To this date, i have only observed two resonant JT circuits in operation posted on this forum.
One was created by BruceTPU
the other was done by PirateBill, using an earth battery and a high-voltage CFL. ( i think it was the Fuji circuit?)
It was evident by the posted waveform, that the JT was both in linear mode, and at a resonant node.

This was reflected by his measurements. Though i do not believe he knew he was at a resonant node.
His analysis was based on current draw vs luminescence, and while it represents the same scenerio,
the perspective may lead one to miss the full scope of the occurance.

[Magluvin]

Been trying things. Worked my way to a 10k pot and as I went, kept adding 10k resistors. The pk-pk across the led went down to near 5v along the way but once I got around 40kohm the pk-pk went up and at near 70kohm to 6.3 pk-pk. Led output is down from posted results. So Ill keep on adding resistance to see if the pk-pk increases. Got up to 50kz so far.

Mags

[MileHigh]

Smoky2:

That was a lot of talk including some straw man talk.

I am sure that you have read and understood what I have repeatedly said:   There is a Joule Thief running in standard mode and there may indeed be something akin to a Joule Thief circuit running as an oscillator in some kind of resonant mode.

All that I have asked you to do is make your case and describe how the device is resonating and show something tangible.  I have said to you repeatedly that I seriously doubt that any oscillation would be at the self-resonant frequency of the main coil of the Joule Thief itself.

I have simply asked you repeatedly to make your case with something tangible and instead you play the "good shepherd" "preaching to the flock" about the "resonance that 'they' don't want you to learn about."

What I am saying to you is that attitude is simply silly.  If you have some data on turning a Joule Thief-type circuit into an oscillator then just share it and lay your cards on the table.

Building a Joule Thief and the playing with it until you get to the point were it ceases to operate as a switching circuit and instead starts to operate as an oscillator is interesting but absolutely not remarkable in any way, shape, or form whatsoever.  What would be interesting would be for you to illustrate that and explain the mechanism for that without any "hocus pocus resonance messiah talk."  Do you get the point I am trying to make to you?  You talk about something so completely unremarkable and try to pitch it as something remarkable.

If you want to show a circuit that oscillates built around a single transistor and a few other passive components - GREAT, share your data.   Will such a circuit still be able to draw power from a battery running at a very low voltage and give you more light output bang for your power buck?  The answer to that in undetermined and the ball would be in your court to show data and explain how that could be done.

MileHigh

[MileHigh]

Magluvin:

Great work and you are doing it right.  Exercising the circuit and seeing what it can do helps others.  So far your waveforms show a standard Joule Thief operating in standard switching mode.

I attached a standard Joule Thief schematic showing two test points that I suggest you connect to your scope channels.  Both test points would be relative to the battery ground.  One is across the LED and the other is at the input side of the base resistor.  You notice that the two test points are for the bottom contacts of the Joule Thief transformer.   So by viewing the two test points you see all of the "action" around the transformer.  Notice that you can also easily derive the current going into the base input of the transistor.  It's just the TP1 potential minus the transistor Base-Emitter forward drop (about 0.7 volts?) divided by the value of the base resistor.  So that allows you to "see" the base current.

When the transistor is switched ON, you know there is a ramp up in the current through the main coil.  Likewise when the transistor switches OFF, you know that there is a quicker ramp down in the current through the coil as the stored energy in the core does a "burn" through the LED and it is also helped along by the supply battery supplying some energy (for a standard Joule Thief).  By looking at TP1 you can make inferences about the LED current also.

MileHigh