Joule Thief 101

[poynt99]

I pose this question for you.  What is the explanation of when we have an ideal inductor as it is defined, that the CEMF would not be ideal as MH claims? What is the limiting factor that says CEMF of an Ideal Inductor is not 100% efficient in what it does? MH wont attempt it. So I humbly ask you. I mean look, if the ideal inductor is everything it is defined to be, then there must be some 'loss' in order for the CEMF to be less than the input. I have described my view on that a few times, whether anyone agrees or not. There has been no explanation from MHs great storehouse of knowledge other than insults, name calling and basically badgering as you say. He cannot give us the answer to that question and he says CEMF is just a measurement as his closest explanation.  So maybe you can shed some light on this. By the way. Do you agree that the CEMF that is in opposition to the input is only a measurement? If you prefer not to answer against him, I understand. But that is not helping anyone.

Why is cemf being discussed? I don't see it being relevant here. If you believe it is, explain.

Also.  From what I have found, when talking ideal voltage source, there is nothing out there on the voltage being variable over time. So ok. MH made up his own idea of an ideal voltage source. What is so ideal about that? If it changes its voltage it does not fit the definition.  So it is just a normal power supply.  Here is the problem I had with that....

The original question posed an Ideal Power Supply of 4v. Brad was correct. The voltage would not change over time if the ideal supply that Brad and I are understanding the definition correctly. The Ideal Inductor was directly across the supply.

Perhaps you both have misinterpreted what the question is saying? You also seem to be missing two or three other parts of the question, where zero volts and -3V is mentioned. Surely you don't believe MH was saying that the voltage source was varying all over the place when it should have been holding steady? I thought I already addressed that, did you miss it?

[poynt99]

"All three of you know very well what an ideal voltage source is (and you know each other does as well), and mags/Brad, you know full well what MH means in his question and/or his posts when he says the voltage source varies."

What sort of power supply would that be? If the voltage can vary, then so can the current. Are we just saying it has no resistance thus no losses?  This would have to be some very intelligent supply architecture for it to have zero internal resistance but the voltage can change as the load requires. Just interested in your explanation beyond just stating it is what it is.


Mags

Mags, do you have a function generator? Does it produce square waves? Can you center the square wave about 0V so that there is a positive half and a negative half of the wave form? If not, surely you are aware that they exist and that they can produce these and other types of wave forms where the voltage might vary with time as it progresses through its cycle, i.e. 50% at +5V, and 50% at -5V for eg.?

Have you heard of an Arbitrary Wave Form Generator? Check it out. It can be programmed to generate almost any wave form imaginable, including the one MH posed in his question. It can be set up so that it is a single shot, exactly as in MH's question.

Now, if we pretend this generator is "ideal", i.e. it has zero output impedance, then this is precisely what MH is referring to in his question.

Any component is "ideal" when and if its impedance is zero. An ideal diode would not only have zero ON resistance, but it would require an infinitely small forward voltage to forward bias it. Any inductor is ideal when its series resistance is zero Ohms (we assume it has no capacitance when it is ideal).

[Magluvin]

If MH actually drew up his own circuit with the associated values that relate to ideal,then he may see the error of his ways.


Brad

Like I can imagine the source he describes as being called an ideal source that would be just defined by zero loss source, but not an Ideal Voltage Source. He wants us to go find and figure out stuff. Well we had done that on this way back before this, what is it called again, oh yeah, fiasco. Thats what it was called.

But if we just begin to think of such a supply, it gets to be more and more impossible  when we consider it has zero resistance and zero loss. What voltage does it begin with? 4v? ok. So the Ideal Voltage Source is strictly defined when we 'go out and look for the answers and yet we remain wrong', so, no, it cannot be variable over time unless we controlled the output. And that poses another legit question. Why are we adjusting the supply over time to investigate an ideal inductor? Why control the source voltage along the way of watching and measuring the functional tests of an inductor? Is there a problem with using an Ideal Voltage Source across the ideal inductor? What problem may that be? Thus we now have the magical lossless automatically adjusting over time power supply. Lol. What determines the voltage change over time? Current increase? Pre programmed time constant according to the value of the inductor being tested? I dont remember that explanation as to how and why the ideal source does this. That explanation would be good to include along the way, and why. Just for general understanding.

I mean if we were to look at it in the real world, the inductor does what it does and the results fit. Where is it in the real world that the supply voltage needs to be adjusted over time to get to know the inductors characteristics? Could we not just connect it to a decent source and measure the singly cycle till max current and disconnect and get those numbers that determine those characteristics? Heck, put the dang ideal 1 ohm resistor(lossless current limiter, not regulator) in there and just use an ideal voltage supply. 

And I believe I understand what you are saying about the inductance being undefined in the ideal world as we never get to a max current level. But maybe what the henry value does affect is the time it takes for current to increase over time. So the inductance value would still be a variable, lol if the thing carries current at all.

Maybe since apparently PW says there is super conducting coils in equipment out there that those inductors, windings, are not yet ideal, while also not being in an ideal world. Consider an MRI may use them. Havnt looked into it but if it is high freq the inductors are dealing with, then we have radiation losses and the coils could conduct and work within the inductor definitions because it is not lossless.    

Just some thoughts

Mags

(Fixed a few things. Mys laptop touch pad has been messing with me on typing and sending the arrow all over and have to do editing to fix.  Funny when I read it after posting they seem to show up easier than in editing. Need to turn off the touch pad. )

[Magluvin]

Why is cemf being discussed? I don't see it being relevant here. If you believe it is, explain.
Perhaps you both have misinterpreted what the question is saying? You also seem to be missing two or three other parts of the question, where zero volts and -3V is mentioned. Surely you don't believe MH was saying that the voltage source was varying all over the place when it should have been holding steady? I thought I already addressed that, did you miss it?

"Why is cemf being discussed? I don't see it being relevant here. If you believe it is, explain."

No problem.  In order for the inductor to impede the input, what needs to occur for that impedance to happen? It isnt just something where we say, Oh, its value is 5H so the time constant for the current rise is what it is. What is it that is pushing back on the input in order to limit it over time? Is that not Counter EMF when it is all said and done? So we apply the input and the intial current sets up the initial building of the field. And that field from each loop cuts the other loops inducing reverse currents that oppose the input. Is that induced reverse current that is opposing the input not called Counter EMF?      

If you agree, then what causes the CEMF to be less than the input in a lossless world? What is the limiting factor that keeps the cemf always less than the input?

So our stand is the possibility of the cemf being ideal in the ideal inductor. If not, as MH says, then we would like to know why. Its not a crazy thought. Ac has stated the same. If we were not really using our brains at all, this would be a non starter idea.  But so far Brad, AC and I, and others along with many more out there, are thinking the same thing. Not just us few.  I spelled it out quite a few times on this forum that if there is an ideal inductor, void of resistance, that there might be a chance that current may not flow under those ideal conditions when there is no loss. If it is ideal, then where do we associate losses enough in that ideal situation that the cemf is less than the input so current will flow and gain over time as we know it?

Mags

[SeaMonkey]

How many Mile'''''s?

https://www.youtube.com/watch?v=Wh2ZjHvlzE4

Here is one more.  Miles certainly does get around!