MH's ideal coil and voltage question

[Magneticitist]

still reading this but have been wrapped up tinkering hardcore with some stuff someone sent me.
just wanted to leave this here for Mags and Bill.  interesting stuff regarding electron movement.
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmmic.html

[partzman]

And there in lies a problem. What about that ideal voltage source,where the current is free to flow during the 0 volt cycle. A rotary switch would mean an open circuit in between contacts,and there go's your current flow.
Why not simulate it Poynt,using the lowest value resistance you can.
We have to remember,it is going to be -3 volt's,not a build up of voltage as the current drop's from 2.8 amp's down to the lower value,the ideal voltage source will place -3 volts across that ideal loop regardless of the current. So lets see if you can get your sim to do that.

Why would it have to be a set value of inductance. Could we not see the effect with any decent inductor?.


Brad

Brad,

Trust me when I say that a sim using an ideal voltage source and an inductor with a really, really small resistance will properly demonstrate the point that MH and others are trying to get across.  The question is, would you believe it and accept it?  To understand this may open up new horizons for you in your quest for OU.

I am not a 'EE' or an 'E' or even an 'e', but I have studied greatly to show myself approved. This is a difficult way to go but one can get an education either formally or informally but we all must be willing to learn.  For example, I could raise a rucus here by stating that Distinti's magnetic theory says Maxwell's equations for electromagnetic waves are incomplete. I would guess that the EEs here would/will take issue with this. The point is, we must all be willing to learn.

Poynt or myself could post a sim showing the answer to the question but I chose not to do so out of respect to MH because he asked me not to.

partzman

[minnie]

  As I understand it in the analogy the torque of the pump is the voltage.
  Am I correct?
           Having a bad day "at the office".
        J.

[poynt99]

The first thing i will say is--have you said the same thing to MH,when he said i did not know what i was talking about and was wrong,when it came to the ICE,which is my speaciality ?

Yes, in private I have talked to MH about keeping his tone in check, and yes I would agree that he still goes a little too far sometimes.

Secondly-can you say without doubt tha MH would have been able to answer the question correctly,without having proof to back it up.

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

Thirdly- Regardless of any answer being considered to be correct,it is just theory based around real world examples. As we cannot make such an ideal voltage source to test the theory,then it remains just that-a theory. Lust as verpies said--just because th erest of the world dose it wrong,dose not mean we have to.

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.

And there in lies a problem. What about that ideal voltage source,where the current is free to flow during the 0 volt cycle. A rotary switch would mean an open circuit in between contacts,and there go's your current flow.

Most voltage sources are close enough to ideal for this test. Yes, a rotary switch may cause some loss due to an imperfect transition.

Why not simulate it Poynt,using the lowest value resistance you can.

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?

We have to remember,it is going to be -3 volt's,not a build up of voltage as the current drop's from 2.8 amp's down to the lower value,the ideal voltage source will place -3 volts across that ideal loop regardless of the current. So lets see if you can get your sim to do that.

As I said above, I have already fully simulated the circuit, as has Partzman. I am sure our results are identical.

Why would it have to be a set value of inductance. Could we not see the effect with any decent inductor?.

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.

[MileHigh]

I already discussed simulating this in the real world on another thread.  Say you had a 2x1000-watt car audio amp.  I am pretty sure they have huge voltage inverters in them so the run off a bipolar supply.  They are giant ideal voltage sources within certain bandwidth and IV limits.  If you could hack into one so that you insert a current viewing resistor at the output such that the voltage sense is on the far side of the current viewing resistor then you should be good to go.  You just need a scope channel for the CVR and I am assuming that the car audio amp is being powered by a car battery.  You connect up your arbitrary waveform generator (or iPhone) to the amplifier.

Then perhaps go to the hardware store and buy a bunch of looped hollow copper pipe for your inductor.  There is probably a better way of doing the coil but that's the one that comes to my mind.

All that you have to do is shorten the timing and lower the voltages and you should be able to do a setup that is a very good facsimile of what we are discussing here.  As long as you don't exceed the IV capabilities of the beefy car audio amplifier you should be fine.

But of course, measurements like these were probably made thousands of times already.  What's of more value is the intellectual understanding and solving the problem on paper.  That's what we are trying to do here.

MileHigh