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Author Topic: MH's ideal coil and voltage question  (Read 188994 times)

Offline MileHigh

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Re: MH's ideal coil and voltage question
« Reply #75 on: May 09, 2016, 03:44:57 PM »
<<< Poynt has just stated that your circuit as defined cannot be simulated,and so your circuit dose not represent a real world device. >>>

Of course it can be simulated.  To my surprise in this case he has to add a resistor.  We have seen him add little phantom resistors many times in the past to get the simulator to run so ultimately there is no real surprise.

The place to simulate this setup is in your head, like I explained before.  Then there are no issues.  I am attaching the "short answer that solves everything" again to this posting.

Free Energy | searching for free energy and discussing free energy

Re: MH's ideal coil and voltage question
« Reply #75 on: May 09, 2016, 03:44:57 PM »

Offline MileHigh

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Re: MH's ideal coil and voltage question
« Reply #76 on: May 09, 2016, 03:52:45 PM »
Brad:

How about this:  Take the identical question and add a 0.00000000001 ohm resistor in series with the 5 Henry ideal coil.  Now you have a real-world coil.

Can you answer the question now?  If you answer that properly then as far as I am concerned your answer will be perfectly legitimate.

MileHigh


Offline tinman

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Re: MH's ideal coil and voltage question
« Reply #77 on: May 09, 2016, 04:13:02 PM »
Brad:

How about this:  Take the identical question and add a 0.00000000001 ohm resistor in series with the 5 Henry ideal coil.  Now you have a real-world coil.

Can you answer the question now?  If you answer that properly then as far as I am concerned your answer will be perfectly legitimate.

MileHigh

Yes MH,now that question can be answered,as we have the needed value to calculate the L/R time constant.

But first i want to resolve your original question-the one this thread is about,as i have done nothing but think about the situation that could exist in this ideal case,and the outcome of such an event.

I am hoping that Poynt will keep working on this with the rest of us here,as i have a feeling that even he may not be sure of the outcome,due to the result of the attempted simulation.

At this point in time,i will stick with my theories and answers given,but it is not yet resolved,and so will continue research toward the answer.



Brad

Offline tinman

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Re: MH's ideal coil and voltage question
« Reply #78 on: May 09, 2016, 04:29:33 PM »
<<< Poynt has just stated that your circuit as defined cannot be simulated,and so your circuit dose not represent a real world device. >>>

Of course it can be simulated.  To my surprise in this case he has to add a resistor.  We have seen him add little phantom resistors many times in the past to get the simulator to run so ultimately there is no real surprise.

The place to simulate this setup is in your head, like I explained before.  Then there are no issues.  I am attaching the "short answer that solves everything" again to this posting.

Your short answer dose not solve your question.

Below you can see what i mean that a small difference in resistance value can have an infinite difference in the end resulting value. One has a finite value,and the other has an infinite value,even though the two resistance values are very close. This is the difference between a real world inductor and an ideal inductor.


Brad


Offline tinman

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Re: MH's ideal coil and voltage question
« Reply #79 on: May 09, 2016, 04:52:15 PM »
Brad:

How about this:  Take the identical question and add a 0.00000000001 ohm resistor in series with the 5 Henry ideal coil.  Now you have a real-world coil.

Can you answer the question now?  If you answer that properly then as far as I am concerned your answer will be perfectly legitimate.

MileHigh

So using your resistance value MH,i have calculated the L/R time constant to be 500,000,000,000.00 seconds or 1388888888.88 hours.
So we can safely say(as poynt did),that next to nothing will happen when the ideal voltage is placed across the  inductor and series resistor-->!OR!,the inductor having a very low resistance value,will causes the current to rise to 63% of 400000000 kiloamps,keeping in mind that we still have our ideal voltage that will drop to a value of 0 across the inductor,but remain at 4 volts acros the resistor /inductor ,now that we have the series resistor,as it dose when using real world circuits.


Brad

Free Energy | searching for free energy and discussing free energy

Re: MH's ideal coil and voltage question
« Reply #79 on: May 09, 2016, 04:52:15 PM »
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Offline partzman

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Re: MH's ideal coil and voltage question
« Reply #80 on: May 09, 2016, 05:16:22 PM »
I've attached an LtSpice sim of a 5 henry inductor with a dc resistance of 1e-11 connected to a 4 volt ideal voltage source for 3 secs.

At the end of three secs we see the inductor current has reached 2.4 amps.  This is as close to a perfect inductor as one could want.

Using the formula that MH supplied that is, delta I = Et/L, this results in delta I = 4*3/5 = 2.4 amps.

What happens if we increase the dc resistance to a higher resistance? The peak current reached will simply be lower than the above depending on the value of the resistance under otherwise the same conditions.

partzman

Offline poynt99

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Re: MH's ideal coil and voltage question
« Reply #81 on: May 09, 2016, 05:20:58 PM »
Brad,

Yes, nothing will happen with the ideal inductor, i.e. it will have 4V (or whatever the voltage is at any point in time) across it and zero current through it for ever and ever. (You can't have both answers.)

Now, replace the ideal inductor with an ideal discharged capacitor, what is the outcome at t=0?

Do you still think with the inductor scenario current instantly going to infinity is a possibility?

Free Energy | searching for free energy and discussing free energy

Re: MH's ideal coil and voltage question
« Reply #81 on: May 09, 2016, 05:20:58 PM »
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Offline tinman

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Re: MH's ideal coil and voltage question
« Reply #82 on: May 09, 2016, 05:31:30 PM »
I've attached an LtSpice sim of a 5 henry inductor with a dc resistance of 1e-11 connected to a 4 volt ideal voltage source for 3 secs.

At the end of three secs we see the inductor current has reached 2.4 amps.  This is as close to a perfect inductor as one could want.

Using the formula that MH supplied that is, delta I = Et/L, this results in delta I = 4*3/5 = 2.4 amps.

What happens if we increase the dc resistance to a higher resistance? The peak current reached will simply be lower than the above depending on the value of the resistance under otherwise the same conditions.

partzman

Unfortunately partzman,it is no where near an ideal inductors outcome,as an ideal inductor never has any current passing through it.


Brad

Offline tinman

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Re: MH's ideal coil and voltage question
« Reply #83 on: May 09, 2016, 05:36:58 PM »
Brad,



Now, replace the ideal inductor with an ideal discharged capacitor, what is the outcome at t=0?

Do you still think with the inductor scenario current instantly going to infinity is a possibility?

Quote
Yes, nothing will happen with the ideal inductor, i.e. it will have 4V across it and zero current through it for ever and ever. (You can't have both answers.)

Well this as you know,was one of my answers. My other answer is because there is no resistance with an ideal inductor,and there for it is a dead short.

Your self,verpies,MH and ION have all stated that there is no voltage across an ideal inductor that has a steady DC current flowing through it. So if it is as you say-nothing will happen when an ideal voltage is placed across an ideal inductor--no current will flow,how can you then say that no voltage will be across an ideal inductor when there is a DC current flowing through it. How did the current flow take place if no current flow will take place when the ideal voltage was placed across it?.


In regards to the ideal capacitor,would we not have the same conundrum?


Brad

Offline MileHigh

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Re: MH's ideal coil and voltage question
« Reply #84 on: May 09, 2016, 05:58:52 PM »
Brad:

You have actually been given part of the answer, and you see that you were dead wrong.  Turn that into a learning experience.

These are the two challenges for you:

1.  Brad gets up the learning curve and understands the original question and then answers it correctly all by himself and clearly demonstrates that he understands what he is doing.
2.  Brad admits that he is wrong when he stated that my response to the harder question is wrong.

I will repost my answer to the harder version of the question on this thread.

MileHigh

Free Energy | searching for free energy and discussing free energy

Re: MH's ideal coil and voltage question
« Reply #84 on: May 09, 2016, 05:58:52 PM »
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Offline MileHigh

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Re: MH's ideal coil and voltage question
« Reply #85 on: May 09, 2016, 06:07:49 PM »
Here is the harder version of the question and the answer:

You have an ideal voltage source and an ideal coil of 5 Henrys.  At time t=0 seconds the coil connects to the ideal voltage source.  The voltage source waveform is 20*t^2.  So as the time t increases, the voltage increases proportional to the square of the time.

The question is what happens starting at t = 0

The answer:

The current through the ideal coil starts from zero at time t = 0 and then increases with this formula:  i = 1.33*t^3.

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

Brad, you need to try to get up the learning curve such that you get to the point where you come back and acknowledge the answer given above is correct.

Offline MileHigh

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Re: MH's ideal coil and voltage question
« Reply #86 on: May 09, 2016, 06:13:23 PM »
I've attached an LtSpice sim of a 5 henry inductor with a dc resistance of 1e-11 connected to a 4 volt ideal voltage source for 3 secs.

At the end of three secs we see the inductor current has reached 2.4 amps.  This is as close to a perfect inductor as one could want.

Using the formula that MH supplied that is, delta I = Et/L, this results in delta I = 4*3/5 = 2.4 amps.

What happens if we increase the dc resistance to a higher resistance? The peak current reached will simply be lower than the above depending on the value of the resistance under otherwise the same conditions.

partzman

Thank you partzman for running the simulation.  I am hoping that this gives Brad and others enough information to answer the full question and demonstrate that they understand the concepts and show competence in the subject matter.  In that sense please refrain from providing further answers to the complete question that defines a multi-part voltage waveform.  The hope is that the interested parties undertake to teach themselves as apposed to being spoon fed the answers.

MileHigh


Offline Magneticitist

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Re: MH's ideal coil and voltage question
« Reply #87 on: May 09, 2016, 06:18:52 PM »
I just want to point out this argument started over an actual inductor. like, a non imaginary, real world, coil that is part of a real circuit.
The argument began when the group was discussing just how the circuit operated. Now I'm no expert, but I'm fairly sure
this inductor has an inductance and a resistance, and I'm sure some capacitance in the windings.. I'm also pretty sure we can track down
the rest of the factors in the circuit such as source voltage.. frequency.. etc.. I have seen no one do that. Instead days have been spent
arguing over a completely fictitious scenario that basically boils down to a basic philosophical argument about duality or the chicken and the egg.

At this point I don't see how we are any closer to agreeing just how the JT circuit originally in question fires below 300mV.

Instead we have moved to the fantasy realm of an ideal hypothetical scenario because MH want's to prove that
Brad just blindly threw the circuit together and has no idea how it works.

At least I learned something.. I learned that even though one can understand the characteristics of an inductor, how to use it
in a circuit, how it behaves in comparison to other components, and how to work out its role in a circuit over time.. none of that
has absolutely anything to do with how an inductor really works unless you can answer some ambiguous question about a
hypothetical coil.

what happens after T=0? well, there's a dog somewhere that probably took a dump, someone's favorite tv show probably came on,
somewhere along the lines the inductor started charging.. oh and it also continued to display characteristics of any other inductor even though
we have to assume that entirely of faith.

I'm assuming since MH has finished his little test exercise, can we go ahead and start figuring out
what's going on in the actual circuit now?

Offline Magneticitist

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Re: MH's ideal coil and voltage question
« Reply #88 on: May 09, 2016, 06:29:56 PM »
Here is the harder version of the question and the answer:

You have an ideal voltage source and an ideal coil of 5 Henrys.  At time t=0 seconds the coil connects to the ideal voltage source.  The voltage source waveform is 20*t^2.  So as the time t increases, the voltage increases proportional to the square of the time.

The question is what happens starting at t = 0

The answer:

The current through the ideal coil starts from zero at time t = 0 and then increases with this formula:  i = 1.33*t^3.

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

Brad, you need to try to get up the learning curve such that you get to the point where you come back and acknowledge the answer given above is correct.


look.. I'm just some dude that loves electronics tinkering and never claimed to be any kind of electrical engineer, but this version actually seems a simpler question.  Though I'm extremely confused as to how there is 0 voltage at 0 seconds when at 0 seconds the coil is connected to the source.

For those of us who are trying to interpret your original question properly out of simple respect, any more details as to 'how' you wanted the question answered would be of great help.


Offline MileHigh

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Re: MH's ideal coil and voltage question
« Reply #89 on: May 09, 2016, 06:51:03 PM »
Magneticitist:

You are way off.  For starters, you threw a lot of mumbo-jumbo talk at this subject earlier when discussing this test.  You are talking more mumbo-jumbo talk now.

Like I already clearly stated to you in an earlier posting, this example has many applications in the real world of your bench.  What we are talking about is real, and there are no philosophical arguments to be made.

We are not interested in the resistance or the capacitance between the windings, at all.  That just makes everything more complicated.  We are not talking about frequency at all.  Nor are we talking about a Joule Thief.  Forget about the usual buzz words and the usual box of tricks, time to get real.

Quote
At least I learned something.. I learned that even though one can understand the characteristics of an inductor, how to use it in a circuit, how it behaves in comparison to other components, and how to work out its role in a circuit over time.. none of that has absolutely anything to do with how an inductor really works unless you can answer some ambiguous question about a hypothetical coil.

It has every damn thing to do with how an inductor really works.  Your problem is that you have been taken out of your comfort zone.  You like to fire off philosophical musings when it comes to coils and circuits, it gives the impression that you have a "higher order" discussion going on about electronics.  The problem here is that we were trying to figure out how a very simple circuit works and you had no idea yourself.  Don't be dismissive of real solid knowledge and make silly cracks about a dog taking a dump.

The message to you is to come down to Earth and if you want to do better work on your bench, then you want to understand this stuff and have complete mastery over it.  Pay attention and try to learn something important.  Drop the mumbo-jumbo talk and be real.

The question still has not been answered, do you want to take a shot at it?

MileHigh

Free Energy | searching for free energy and discussing free energy

Re: MH's ideal coil and voltage question
« Reply #89 on: May 09, 2016, 06:51:03 PM »

 

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