Joule Thief 101

[tinman]

 author=MileHigh link=topic=8341.msg483911#msg483911 date=1463059213]

MileHigh

Verpies is in agreement and you saw his quote.  He also made some other somewhat confusing posts, but I am talking about the post that counts.

I dont remember seeing such a quote that he agreed with you--i will have to go find it--it may be there,im not sure.

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.)

Well fancy that. A permanent magnet inducing a current flow in a superconductor,that creates an equal and opposite magnetic field that apposes that which created it
And you said a PM could not do useful work-->wonder what created that current flow in the superconductor?.

Do you remember verpies saying that a voltage could not produce a current flow in a superconductor?,but only an external magnetic field could.

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.

Oh i can do that,if i could be bothered with all the math,and it would take me some time to answer your question if we swapped out ideal for real world stuff. But im interested in the !ideal! part. Infinite Tau's,no resistance,infinite currents-->sounds like much more fun to me.

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.

How could it be out of context MH?. You either stated that a voltage cannot exist across an ideal coil when a DC current is flowing through it,or you didnt say that--which is it?.


Brad

[minnie]

   MH. the original inductor question was very thought provoking for me and I've
learned quite a bit. I would love to do the experiment.
  Obviously people use ideals in circuit calculations every day and they're very
useful.
   Unfortunately the tinman can't grasp concepts, he just knows.
          John.

[MileHigh]

Webby:

BS the question was "false."

Here is the question:

<<<
You have an ideal voltage source and an a coil that's 5 Henrys with a wire resistance that's 0.00001 ohms.  At time t=0 seconds the coil connects to the ideal voltage source. For three seconds the voltage is 4 volts.  Then for the next two seconds the voltage is zero volts. Then for two seconds the voltage is negative three volts, and then for the next six seconds the voltage is 0.5 volts.  Then after that the voltage is zero volts.

What happens starting from t=0?
>>>

So go ahead, and tell us what is "false" about that question.

The simple fact is that Brad can't answer it, or he can give all of us a pleasant surprise and prove me wrong.

Are you talking about the shopping cart moving and the person pushing it moving in the same direction?

Are you talking about the force between the person pushing the shopping cart and the shopping cart?

Are you talking about the common point of observation,, that would be the ground,, which sees the total force and the reaction?

This is a real-life example.  The person moves along with the shopping cart as it accelerates.  Yes the force is between the person pushing the shopping cart and the shopping cart.  The point of observation is not relevant, you have an external force accelerating a mass.

Do not bring resistance into this discussion or angles or anything like that.

MileHigh

[MileHigh]

   MH. the original inductor question was very thought provoking for me and I've
learned quite a bit. I would love to do the experiment.
  Obviously people use ideals in circuit calculations every day and they're very
useful.
   Unfortunately the tinman can't grasp concepts, he just knows.
          John.

Well I am glad that you are getting something out of it.  That's really what the ultimate goal is.

MileHigh

[MileHigh]

Brad:

<<< I dont remember seeing such a quote that he agreed with you--i will have to go find it--it may be there,im not sure. >>>

This is what Verpies said:

<<< In an ideal inductor having a finite inductance, in series with an ideal voltage source, the current will be able to flow and it will increase linearly in time without a limit. >>>

I already reposted that to Magluvin in post #2554.  It comes from his response to you.

<<< And you said a PM could not do useful work-->wonder what created that current flow in the superconductor?.  >>>

Mr. Hand created the current flow in the superconductor.

<<< Do you remember verpies saying that a voltage could not produce a current flow in a superconductor?,but only an external magnetic field could.  >>>

I don't remember exactly and I would have to see it again to know the context.  I found that he was going through a rather cryptic phase in his comments and several of them were puzzling or were too minimalist and left out a lot of details.

MileHigh