Here we go again.  Who said that ideal voltages have to be fixed and can't change in time?  It's an ideal voltage, I can say it does whatever I want it to do.  In my second example I state that the ideal voltage v = 20*t^2.  So the ideal voltage increases in value proportional to the square of the time.  There is nothing stopping me from saying that.

What about your function generator when you set it to a triangle wave and you connect it to your circuit?  Supposing that the triangle wave is somewhat attenuated especially at the peaks because of the load on it from the circuit.  Well, what if I said that my "ideal voltage source" had an identical waveform to the somewhat attenuated triangle wave output from your function generator?  Under those static load conditions then the ideal voltage source that clones your function generator output and the function generator output are indistinguishable.  That means you can look at the output from your function generator as being a time-variable ideal voltage source as long as the load condition remains static and unchanging.

@MH - @verpies

Common guys. We have been through this how many times.

Here is a common definition.
"An ideal voltage source is a voltage source that supplies constant voltage to a circuit despite the current which the circuit draws."

In this definition, one can summarize that there is no variability in the voltage source. If you adjust your voltage at 4 volts, it stays at 4 volts regardless of any current draw.

In the video I posted on my shorting a wire over a battery, the battery is not an ideal voltage source so the voltage will drop as I short it with that wire. But in that case it is still backed up with 100 amps so that wire went zap in a few seconds. This for @tinman and myself and many others was the complete basis of why the question of ideal voltage on an ideal inductor was more then moot, it approached ludicrous because for us, like I said in my post, come hell or high water, that voltage should never change. This for us signifies a DC voltage holding a fixed straight line as in @partzman's graph showing the first three seconds as a straight 4 volts. Where is the variable in time there for the voltage. None. Yes it will show a variable current rise from t0 onward.

This is why I was stating that for any voltage to change across the terminals of the ideal voltage, it has to come from the inductor.

This was the whole basis of my prior post and of most posts from @tinman and the root of all this commotion that started with an innocent JT circuit.

A time variable ideal voltage source, for me, is not a DC fixed ideal source but either an AC ideal source or a DC ramped ideal source. Totally different animal. But in either of these three, using the term IDEAL will still signify that once they are set, they are set for life. No change possible and thus they become the fixed anchor to other variables that one can experiment with.

Hmmmmmmm.

wattsup

@MH - @verpies

 This for us signifies a DC voltage holding a fixed straight line as in @partzman's graph showing the first three seconds as a straight 4 volts. Where is the variable in time there for the voltage. None. Yes it will show a variable current rise from t0 onward.

wattsup

Wattsup,

Yes, I created that ideal voltage source and applied it to the ideal inductor for three seconds and that voltage source was faithful to it's duty and it did not change for that duration.  I could however, create a new ideal voltage source of 0 volts in magnitude and replace the original 4 volt ideal voltage source and it too will do it's job. In a sim, I can do this in few ns of time and maintain a duration of my choosing.

I can continue to replace each ideal voltage source with another as I choose since there is no law I am aware of which prevents me from doing so.  Each ideal voltage source I create has the ability to maintain it's magnitude no matter the load.  Proceeding in this manner allows us to be able to solve MH's problem.

partzman

Edit

@partzman

I know that. Your are on a sim and that sim is not simulating an ideal voltage as per the definition otherwise it would not change. Don't you get it. If your sim could simulate an ideal voltage it would have stayed at 4 volts all the time according to the definition. There is no ideal voltage in your sim. It is just simulating an applied voltage given the other parameters and it will change in time.
Actually there is no point in using a sim with an ideal voltage because you will always have the same voltage straight line.

The idea of the ideal voltage is to maintain a fixed voltage source while you can vary other parameters that cannot vary the ideal voltage but will provide you with how the circuit works when you, let's say, vary the resistance, or inductance, or impedance or capacitance while that ideal voltage always stays the same. The require gain or reduction in current will be automatic but the voltage will never change. You can then measure across different components in the circuit to see those changing values but the ideal voltage will never change. Otherwise what is the point in having an ideal voltage when it is just simple voltage.

@all

Common guys. There is process, there is teachings but there is also logic and logic has to win every time. At least this is what has been paying my great salaries for years. Nothing beats logic.

Either that or come forward and convene that this question does not require an ideal voltage source to propose the teaching you wish to promote, because it just does not click at all. It should at least send alarms bells ringing when other @members here cannot adjust to your line of thinking that maybe the teaching requires some "fine tuning".

wattsup

Surreal is right.
Your thought-experiment ideal voltage source has a virtual knob on it that says "Voltage output" right? And you can virtually reach out and turn that knob up and down, can't you? Thus making a simple time-varying ideal voltage source. Replace the "knob" with whatever virtual control system is needed to vary the output on whatever time schedule you like. What is so difficult to understand about that?

Absolutely. It perplexes me why you would even question this.

300 years ago,89% of the worlds population believed in God. Today only 26% of the worlds population believe in God---the rest have seen the light.

Not sure what you mean by "theory based around real world examples", but as I've already explained, and MH did also a while back, we don't need a perfectly ideal source nor inductor to prove out the equation that MH posted, which determines the final value of current in the inductor, based on the L and t, and initial current Io.

Your theory being based around real world applications,is based on the fact that there exist a resistance-no matter how small. In our ideal situation,that resistance is no existent,and no energy can be dissipated anywhere in that ideal circuit loop. The energy now stored in the ideal loop at the 0v phase ,must be dissipated before the ideal voltage can set a current flowing in the opposite direction.

Most voltage sources are close enough to ideal for this test. Yes, a rotary switch may cause some loss due to an imperfect transition.
I have already done so. A number of posts back I gave a recommendation as to the L/R ratio that would still provide results "close to ideal", at least close enough for our purposes. I established this level (50:1) by using the sim with various values of R to get 5% error on the final current. Did you miss that post? It was done with the simulation. I have already posted a partial plot of the current, did you miss that also?

No i did not miss the post.
First,i do not think you grasp the difference between a very low resistance value,and no resistance--the difference is infinite,and so the outcome has an infinite difference.
Second-the voltage in this ideal circuit is seen as being in series with the inductor,but as far as the current go's,the connection is both a series and parallel connection. So example 3 that verpies posted some time back,represents MHs circuit as far as the current flow go's,that being the inductor has a short across it's terminals as far as the current is concerned.

As I said above, I have already fully simulated the circuit, as has Partzman. I am sure our results are identical.
If you followed my posts on establishing the L/R ratio for a "close to ideal" inductor, you would know that any value of inductance can work, as long as we are aware that a 50:1 L/R ratio will present a 5% error in the current values. The current will be 5% (or thereabouts) less than the value predicted by MH's equation.

When that L/R =0,what is your ratio then?. 50:0 ?
As you can see,we went from a real world obtainable calculation,to one that dose not exist.
This is what i mean by trying to use real word values against values that just are not there,and expecting to arrive at an accurate outcome.

I have spent countless hours,and thousands of dollars on experiments--not to mention time.
I have helped those purchase equipment that they otherwise could never hope to obtain. I have spent time organizing fun competitions ,and donated prizes to those judged as being the most innovative at what they built. And yet here we have MH,sitting in his rocking chair,not lifting one finger(other than to type)to help the cause.

I will leave you with one thing to think about Poynt--->
Are the books ever going to explain the TPU?. Is what you know going to line up all perfect to that of the operation of the TPU.
Perhaps this is why it(the TPU) still alludes all those trying to replicate it's effect--your trying to place known real world values against values that are infinite--the energy being delivered by the TPU seems to have that value--infinite.

I love that saying by verpies-->just because the rest of the world got it wrong,dose not mean we have to.
Maybe we can learn something from that quote.


Brad

It is perplexing to me to see these questions 

Oh, C'mon! - these were rhetorical questions.  I was not seeking answers to them.  I was provoking some thinking.

To clarify for all interested, one simple answer to cover all questions as to what an ideal voltage source is:
An ideal voltage source is a source that outputs a voltage according to what it is set to, no matter what load is connected to it. This does not preclude ideal function generators.

Of course, but this needs to be stated explicitly, since apparently some people are under the impression, that an ideal voltage source is a constant voltage source

Oh, C'mon! - these were rhetorical questions.  I was not seeking answers to them.  I was provoking some thinking.
Of course, but this needs to be stated explicitly, since apparently some people are under the impression, that an ideal voltage source is a constant voltage source

C'mon yourself. Your question about whether MH knows what an ideal voltage source is, is absolute bunk.

After that it seemed you were the one that was lost. I encourage you to avoid the so-called rhetorical questions, and instead try to help Brad understand why his thinking on this affair is a little off the tracks.