Joule Thief 101

[MileHigh]

Brad:

<<<  I personally dont care what you think,as im interested only in your original question. >>>

What a complete farce.  You start this thread to specifically answer the question and say there is a problem with an ideal coil and now you are exposed as not being able to answer the same question with a real coil.

<<< Now what you have to do,is explain to everyone here,how you can say that a voltage cannot exist across an ideal inductor that has a DC current flowing through it,and then say you are going to produce a DC current through an ideal inductor by placing a voltage across it  >>>

What a complete farce again.  I never said that there would be a DC current though an ideal coil if you place a voltage across it.

For the fourth time, what is wrong with you here?  What's going on?

[tinman]

Brad:

<<< I do not remember seeing verpies in agreement with you. I did see he agreed with one of my posts--did you miss that?.
Partsman and poynt are yet to show a sim of an ideal inductor doing what you say it dose. Yes that right,they must include some resistance for the sim to sim lol. >>>

  He also made some other somewhat confusing posts, but I am talking about the post that counts.  The sim is not relevant to this discussion and it's probably been explained to you at least four times why the resistor has to be added.  What they themselves state is what counts and we are in agreement.

So, you are non-responsive to this question and you are avoiding it.

<<< I have answered your question correctly.
You cannot place an ideal voltage across an ideal inductor,as an ideal inductor dose not exist.
That being the case,all answers are theories only,as the answer cannot be proven to be correct. >>>

So you are non-responsive on the issue of answering the question where you use a real-world inductor with a series resistor instead of an ideal inductor.

So that means that you are incapable of answering the question at all and you are in the same boat as Wattsup and EMJunkie.  Six years of experimenting with coils, countless discussions about electronics on the forums with experts, and when presented with a circuit that consists of a power supply and only two components, a resistor and an inductor, you can't answer it.  So much for all the lols and attitude, the real joke is on you.

<<< We already know that a superconductor produces an equal and opposite magnetic force to that which created it. We know that current can flow through a superconductor without a voltage across it. An ideal inductor would be wound with superconducting wire-hence no resistance. So what is the difference between the two MH? One has it's current induced by the EMF placed across it,and the other has it's current induced by the external magnetic field.
Your saying one will work--produce the equal and opposite,while the other will not.  >>>

Your example is just two magnets in opposition, and that is in no way comparable to a voltage source exporting power into an energy storing device that also responds with an equal and opposite EMF.  Power does not flow in one example and power flows in the other example.  (See the shopping cart example.)

<<< You didnt ? 
Are you sure?. >>>

You better believe that I didn't say it you naughty little imp.  This is your cue to pull up a quote out of context.

So, you are incapable of answering the question and the thread has degenerated into mush.  That is par for the course.

MileHigh

Verpies is in agreement and you saw his quote.

Quote verpies
Since an ideal inductor must have a zero resistance, this means that it must be shorted (if it ain't shorted, it ain't ideal) and it becomes physically impossible to connect any real voltage sources in series with it.

Otherwise, I agree with the above statement.  Not only an ideal inductor is devoid of an asymptotic V/R current limit but also the current through an inductor of infinite inductance, that is somehow connected to an ideal voltage source, could never change because of the implied zero di/dt at any voltage.

Of course, it is debatable whether an ideal inductor must have an infinite inductance.  Some would say that it is enough for it to have zero resistance and zero parasitic capacitance.

However it is possible to externally change the magnetic flux penetrating a shorted ideal inductor. Doing so will instantaneously cause a current to circulate through it *, in order to maintain the previous flux level penetrating its windings.  This is a voltageless current! - it cannot be measured by a voltmeter and it was not caused by a voltage source.

Last but not least - inductors are current devices and voltage creates no effects in them.  Voltage cannot even be measured in shorted ideal inductors (neither practically nor theoretically!). Measurement of voltage (emf) is meaningful only for non-ideal inductors (e.g. open inductors or inductors with series resistances).  Open inductors or inductors without current flowing though them are dummy inductors - they create no effects on the environment.  Voltmeter deflection notwithstanding.

Brad

[MileHigh]

Brad:

The bottom line is that you can't answer the question for a real coil or for an ideal coil.  And you don't even understand what an ideal coil is.

It's a farce.

MileHigh

[MileHigh]

Brad:

<<< Quote verpies
Since an ideal inductor must have a zero resistance, this means that it must be shorted (if it ain't shorted, it ain't ideal) and it becomes physically impossible to connect any real voltage sources in series with it. >>>

I assume that the red highlighted text is what you are focusing on?

What he is saying is that if you connect a real voltage source to an ideal coil, then you introduce a resistance into the current loop and the ideal coil will lose it's inherent ideal property of no resistance with respect to the full circuit.  The current will not rise indefinitely in this case, it will be limited by the resistance of the voltage source.

On the other hand, if you connect an ideal voltage source to an ideal coil, then the current rises indefinitely.

That's my understanding of what he is saying.  So from what I see you are not making any kind of point.  He is not backing you up in any way at all.

[tinman]

What a complete farce again.  I never said that there would be a DC current though an ideal coil if you place a voltage across it.

Have you lost your marbles MH ?
This whole thing you have been peddling is about how you can place a voltage across an ideal coil,and a DC current will flow through that coil.See below



Time..........Voltage.........Current
0...............0.................0
1...............20...............1.33
5...............500.............166.67
10.............2000............1333.33
20.............8000............10666.67
50.............50000..........166666.7[/quote]

For the fourth time, what is wrong with you here?  What's going on?

Me?--i think you have gone completely wakadoo MH.

And for the record,i stated that you said that a voltage could not exist across an ideal inductor while a DC current is flowing through it.
And yet above,you have managed to do what you said couldnt happen.

I dont know what is going on with you MH,but you need to make up your mind here.
Can a voltage exist across an ideal inductor that has a DC current flowing through it or not?--it's a very simple question,and you cant have two answers as you have above.


Brad