Joule Thief 101

[MileHigh]

Brad:

Nice little try to say something that actually sounded reasonable in the second half of your posting.  The problem is that you completely and utterly destroyed your credibility in your posting #2607.

You are toast.

MileHigh

[MileHigh]

Nice that you added in a resistance and dropped the zero capacitance MH,, that changes the question and as such your posted question now is not the question under scrutiny.
False.

I actually explained that and why friction IS within your real world example you have provided.

Where does the force come from that the arms are pushing against to push against the shopping cart MH,, putting the cart before the arms maybe??  and doing that without any feet,,

Why is it that the legs have a larger input than the arms MH? when down here on the surface of the planet where there is gravity,, you know "in the real world"

Since you can not calculate the inductance of a coil with zero resistance and zero capacitance, (you have not been able to show that you can so you must not be able to do it,, is that not your methodology?) then you must not fully understand inductance. ( again more of your methodology)

Ah yes Webby, you are definitely a soul-mate for Brad.  Here we have the poor kid in the grade 11 Physics class that "just doesn't get it" and continuously interrupts the teacher with dumb questions and squanders valuable time from the whole class on a consistent basis.

You are incapable of extracting the relevant information in the story and realizing what the example is actually all about.  The example is just about a force pushing on a mass, and the mass accelerating and pushing back with equal force.  That's all there is to it and the rest of the story is just window dressing to bring home the point that we experience these kinds of things in real life all the time.  It's the same story with the problem student bringing up capacitance in the 5 Henry coil discussion when capacitance has never even been discussed and is not on the table.  It's extraneous noise from the problem student.

You can just keep on being the problem "thread child."

MileHigh

[poynt99]

MH

Now tell everyone here how you can have a coil with an inductance value of 5 Henry's ,and a resistance value of 0.
When dose induction end in an inductor ?

The same way you have a 5F capacitor with an ESR of 0.

Both cases are fictitious (ideal components don't exist), but it makes them no less of an inductor or capacitor. In fact, simulations don't require an ESR, and in most cases they are ideal caps.

[Pirate88179]

Not that it matters but, back to the shopping cart for a moment...

The frictionless cart will still resist any movement because it has mass, especially if it is full as stated.  Yes, it will move more easily due to being frictionless but, F=MA still applies.

I realize that MH was trying to make a point about electronics so my post makes no difference, I just did not want folks to forget about inertia in the cart example.

Bill

[MileHigh]

Webby:

I know, these things are tough:

You go to the supermarket to shop for food.  You get a huge amount of stuff and your shopping cart is very heavy.  You are stopped, and then you push on the cart with a continuous even force.  How about that - the heavy shopping cart is pushing back at you with exactly the same amount of force.  You also notice that the shopping cart is starting to speed up and you have to keep quickening your pace.

This just shows that force = mass x acceleration and there are equal and opposite forces, THAT'S ALL.  The friction of the wheel bearings is incidental and not discussed.  However, since this is a direct analog of a voltage source across an inductor, an astute and wise person would realize that the small friction in the wheels that was not mentioned is a very rough analogy for the wire resistance of a real inductor.

Think about this:  What if the shopping cart was a "magic" 22nd century shopping cart and instead of being on four wheels with bearings, the shopping cart floated one inch above the floor through magnetic levitation.  That means when you push on it it glides frictionlessly across the floor.

This is mentioned because if you remove the wheel bearing resistance, then the floating shopping cart resembles a dreaded ideal inductor.  And YES, I AM EXPECTING the person reading to be wise and astute enough to ignore air friction for this analogy.  I have an expectation that some people might be able to appreciate the concept that I am trying to get across.

Think about this:  Imagine the shopping cart is stopped, and it has infinite mass.  Then, you push on it and then no matter how long and no matter with how much force, the shopping cart doesn't budge an inch.

This is mentioned because the infinitely massive shopping cart is a perfect analogy for the infinitely large inductor.  I am expecting some people to clue in on this pretty obvious fact.

Obviously my expectations were too high.

MileHigh