Joule Thief 101

[MileHigh]

Partzman:

That's awesome, thank you so much for running that sim!  I have to laugh about the dcr = 1e-320.  That means you can compute the solution with a time constant that's way way more than 10,000 trillion times the age of the Universe!   But if you set the dcr to 0 then we all die and we have a singularity and time folds in upon itself...

MileHigh

[MileHigh]

<<< My questions then is, at what point do we all of a sudden lose the property of inductance as we decrease the dcr and become either a short circuit or an infinite inductance?  >>>

Perhaps Brad can shed some light on that one...

[Magneticitist]

Magneticitist:

I am not going to argue this any more. You are just going to have to accept or cope with the fact that people can discuss circuit behaviour using ideal components and then very easily apply that knowledge to the actual circuits that they are working with on the bench.  Your argument is invalid, and I have heard it countless times before from people in a similar position to you.

The question as posed without a single modification can be answered with 100% accuracy.  Then, a keener could get a big negative feedback operational amplifier, insert a resistor for current sensing just before the output of the amplifier and the voltage sense, and then make extremely accurate measurements of the ideal voltage and associated current being put into the device under test.  For example, the device under test could be a single low-resistance coil or some kind of filtering circuit.

If you don't accept this, then there is nothing that I can do about it.  It's not for me to convince you, it's for you to convince yourself and change your attitude and embrace knowledge and embrace stuff that will help you do better experiments.

MileHigh

I really thought I was making it clear that I was in total agreement with you on that statement in bold. But in this situation the mixture of ideal source and ideal inductor made the real world comparison a mathematical impossibility, that is the problem. The question you posed could not,
cannot, and for all we know, will not be answered 100% 'perfectly'. Your modification of the question involving an R value could however as far as I can tell.

[Magneticitist]

does 'pure' inductance mean infinite inductance? which could possibly be construed as 0 inductance?

[Magluvin]

It is really not such a huge mental leap to imagine an inductor with zero resistance.  Can you imagine an inductor with 0.000001 ohms resistance?  Can you imagine an internal combustion engine where the main crankshaft bearings are replaced by "magic" bearings having no resistance?

I told Brad to go ahead and try to answer the question by adding a 0.000001 ohm resistor to the inductor to "fix the problem" and he passed on that.  So zero ohms or 0.000001 ohms, Brad was incapable of answering the question.  Progress is currently running at about one millimeter per day.

Anybody can open up a book or do some Googling.  Every single student that takes an electronics course ends up perfectly understanding ideal capacitors and ideal inductors. Think of the ICE as a very similar hypothetical example.

Sometimes things seem to be tough and you have to learn then.  That's all there is to it, you have to learn them and master them.  Repeatedly saying "the current goes to infinity because the resistance is zero" is ridiculous, you absolutely must learn what inductance is if you are going to progress and get more out of your experimenting.  If you truly knew what inductance really is, you would scoff at the notion that the current goes to infinity in an ideal inductor.

I dont see the problem with learning inductance while including resistance.  My build of Lasersabers motor has 24 coils in series. 3200 turns of 42awg each, 650ohm each coil. 15.6kohm all in series. each is 83mh for a total of near 2h. While running there isnt much if any curve of current rise. Looks fairly square pulses.  So on the far end of resistance where it is very high, the field tends to build very quickly with all that resistance (and inductance) because the current is more restricted from rising any further due to high voltage division across the board.

I just dont see that one would have to learn inductance through ideal circumstances. All one has to do is try say 3 different resistance levels, very low, medium and very high, with a known inductor and see the effects, and it would be real world effects that would be learned.

Mags