Joule Thief 101

[sm0ky2]

I am not sure of what you mean by that.  The more information the better when discussing electronics.

ummm

ok

Ampere Turns per Weber
Reluctance (R) = MagnetoMotive Force (Ampere-turns) divided by Flux in Webers.
Hopkinson's law

Length of the wire divided by the cross-sectional area times the magnetic permeability of the material....

It translates directly to Henries, of magnitude, and in self-resonance, reluctance becomes = 0.
The capacitive counterpart also disappears and the capacitor itself takes on a purely inductive behavior.

https://translate.google.com/translate?hl=en&sl=zh-TW&u=http://140.114.17.97/circuit/ch14.htm&prev=search


In the future if you want to play ignorant with me,.. please go back and delete all your posts where you discuss the details of that which you claim to not know......

[MileHigh]

No, I am simply asking you what kind of point you are trying to make, I was not asking you for definitions.  I made a point that the JT circuit was basically continuously drawing power from the supply battery under normal operation and your response was, "You are forgetting the reluctance factor of the inductor in self-resonance."

What kind of a connection are you making and what kind of point are you trying to make?  I know what self-resonance of a coil is but I don't know what you mean by "reluctance factor" here.  I know what the reluctance of a magnetic flux path is.  A coil with a core material in self-resonance will act as an AC short-circuit and you are left with the DC resistance of the wire.  Presumably the core material will also burn off a certain amount of power due to hysteresis.

If I assume a standard JT circuit but no explanation for how it is operating as an oscillator and how self-resonance of the coil ties into all of this and what a "reluctance factor" is and having no timing diagrams, I am simply not sure what you are meaning and what kind of point you are trying to get across.

Call it a little pet peeve of mine if you want, but the forums have thousands of "discussions" about electronics by people with limited knowledge of electronics with no schematics to reference and no timing diagrams.  In almost every case they are pretentious nonsense discussions that don't really mean anything and are in essence unworkable wild speculation in the from of a fake back-and-forth dialogue between two posters that is disconnected from the reality of the circuit.

[tinman]

Even smaller:

https://www.youtube.com/watch?v=ekPh9p4YECE

[Pirate88179]

https://www.youtube.com/watch?v=ekPh9p4YECE

Brad:

Nice.  I have about 40 of those led garden light circuit boards lying around here, those chips they use make a decent JT.
Is that button cell 3 volts or 1.5?  Will it run those down to low voltage as well?

Bill

[sm0ky2]

No, I am simply asking you what kind of point you are trying to make, I was not asking you for definitions.  I made a point that the JT circuit was basically continuously drawing power from the supply battery under normal operation and your response was, "You are forgetting the reluctance factor of the inductor in self-resonance."

What kind of a connection are you making and what kind of point are you trying to make?  I know what self-resonance of a coil is but I don't know what you mean by "reluctance factor" here.  I know what the reluctance of a magnetic flux path is.  A coil with a core material in self-resonance will act as an AC short-circuit and you are left with the DC resistance of the wire.  Presumably the core material will also burn off a certain amount of power due to hysteresis.

yes. That IS the point I am trying to make. magnetic reluctance becomes non-effective in the circuit. There is no effective "resistance" placed on the wire by the induction of the core material.
Yet, the core material still becomes energized, and the resultant field collapse represents itself through the coils inductance. Hysteresis is minimized in resonant operation of the core. The flux graph is sinusoidal as well, 90-degrees to the electric.

If I assume a standard JT circuit but no explanation for how it is operating as an oscillator and how self-resonance of the coil ties into all of this and what a "reluctance factor" is and having no timing diagrams, I am simply not sure what you are meaning and what kind of point you are trying to get across.

Call it a little pet peeve of mine if you want, but the forums have thousands of "discussions" about electronics by people with limited knowledge of electronics with no schematics to reference and no timing diagrams.  In almost every case they are pretentious nonsense discussions that don't really mean anything and are in essence unworkable wild speculation in the from of a fake back-and-forth dialogue between two posters that is disconnected from the reality of the circuit.

to that I agree.

The "reality" of the circuit, was presented by Edwin Armstrong in 1912. This is designed to be a resonant tank circuit. It was used exclusively in the Steven Mark TPU, as the prime exciter.
The same technology which powered radios in the 1940's before we had commercial batteries.
these radios (although not very loud) required no external power source. Not only that, they were well known at the time, for building up radio interference waves that would disrupt signals for miles around the device. Which ultimately led to its' replacement by a less invasive technology.

"Constructive Interference", "Positive Feedback"

If you somehow missed this point during the 136,000 pages of Joule Thief discussion, then I apologize for jumping on your case. I assumed you already knew what we were talking about here.
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Modern day "joule thieves" place switching transistors in digital mode with inefficient diodes, successfully destroying the resonant effect.

There is still "some effect", because of the natural SRF of the circuit being the dominant factor between the inductor and the tank. but it is disrupted during each cycle, thus a heavier drain on the source than a resonant LRC would or should represent in ideal operation.

This is why a modern day analysis of a JT circuit, observes a wide range of inefficiencies in the circuit.

It is a simple concept, which Americans are indoctrinated to NOT observe.
they teach us these things are bad in circuits, and every way to get RID of this effect.
simply reverse your training to do the opposite.

invite these extra energy levels to build up all they want to
like strumming a string over the resonant cavity of the guitar.
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Here are two images of transistors switching. the one on the left is a transistor operating outside of linear mode. There no be resonance when the transistor scope shot looks like this.

The image on the right shows a transistor operating in the range of its' linear mode of operation. due to the particular circuit it is in, it is biased slightly below the actual linear value, but still within the range.
Notice, that the signal shown on the scope is the input signal, NOT the transistor function.