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Author Topic: Testing the TK Tar Baby  (Read 1998466 times)

TinselKoala

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Re: Testing the TK Tar Baby
« Reply #4680 on: August 23, 2012, 10:22:16 AM »

Making progress there are we, .99? I see someone dodged your question about the resistor that was sent, while confirming that they did send one. Of course someone can't be arsed to get up, go find it, and LOOK AT IT and tell you what it is.


mrsean2k

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Re: Testing the TK Tar Baby
« Reply #4681 on: August 23, 2012, 02:56:51 PM »
@poynt


I think there's room for confusion with your answer to...


"IS it the rule that the measured rate of current flow through a circuit must be consistent.  In other words it cannot be greater at one element than at another?"


I realise you're answering with a specific context in mind there (AC at a particular frequency range, in a particular circuit), but is it safe to assume you're sharing enough context with RA that obvious exceptions like DC parallel resistance won't be thrown back into the mix when it suits?

picowatt

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Re: Testing the TK Tar Baby
« Reply #4682 on: August 23, 2012, 06:36:35 PM »
@poynt


I think there's room for confusion with your answer to...


"IS it the rule that the measured rate of current flow through a circuit must be consistent.  In other words it cannot be greater at one element than at another?"


I realise you're answering with a specific context in mind there (AC at a particular frequency range, in a particular circuit), but is it safe to assume you're sharing enough context with RA that obvious exceptions like DC parallel resistance won't be thrown back into the mix when it suits?



I think .99 has been about as clear as possible without overcomplication that would surely only confuse.  He started out the discussion with DC conditions before moving on to AC.  Whether or not she can understand and visualize the difference between the two is another question.

The point is that even if Q2 is turned off with regard to DC, the AC current current path is ALWAYS there via the MOSFET capacitances (i.e., Ciss and Coss).  Stated otherwise, AC current can flow thru the MOSFET capacitances irregardless of the on or off state of the MOSFET.

In fact, when the voltage at the drains of the MOSFET's is at their minimum (less than 25 volts), the input capacitance (Ciss) for a single IRFPG50 MOSFET increases to over 7,000pF and the output capacitance (Coss) increases to over 5,000pF.  For the four Q2's in parallel, those numbers are 28nF and 20nF.  In other words, the MOSFET capacitances are not a singular fixed value, but are dynamic, and the capacitance values typically increase as the drain to source voltage decreases.  This is why the waveform in FIG4 slows down when Vds is below 25 volts (i.e., the longer charge/ramp time at the negative trough of the waveform in FIG 4).

Regarding inductance, she needs to understand that the amount of AC current flow is determined by, and limited by, the impedances at the observed AC frequencies, which requires adding or accounting for the inductive reactance of the components and wiring.

A 2" length of 12 gauge wire has about 40nHy of inductance, which has a reactance of about 1 ohm at 2MHz.  So, even if a .25 ohm non-inductive resistor is used for the CSR, if the 'scope probes are connected to a point 1" on either side of the CSR, it will cause the CSR to actually be a 1.25 ohm resistor at 2MHz.

A wire is not always a wire, and in the instance above, measurements made using just a 1" length of wire connected to each end of a perfectly non-inductive CSR will cause a very large error, indicating 4 amps when in reality only .8 amps are flowing (and that assumes using 12 gauge wire!).

Therefore, very short lead lengths are required.  In fact, it would be advisable to increase the CSR value to between .5 and 1 ohm to decrease the percentage error caused by lead inductance.  The best non-inductive resistor I have found has 10nHy when measured .2" from the package, which would add .112 ohms of reactance to a .25 ohm resistor at 2MHz, which represents a very significant percentage error.  Increasing the CSR value to .5 or 1 ohm would reduce the percentage of error caused by the .112 ohms of lead reactance (and again, that's .2" from the resistor package).

Also, as the NERD waveform contains a multitude of frequencies and harmoonics, power calculations must be made individually for all of the observed frequencies (at least the five most dominant frequencies, as would be observed in an FFT spectral plot).  One cannot simply use the indicated trigger frequency as the singular frequency contained in the waveform.  This would only be the case if the waveform were a perfect sine wave with 0% THD.  At the higher frequencies and harmonics contained in the waveform, inductive reactance becomes a more significant source of measurement error.     

As an aside, someone should let her know that if she is going to discuss resistor values using European notation, the "R" replaces the decimal point.  A 50 ohm resistor is 50R, not R50.  R50 would be a .5 ohm resistor.  More typically, a .5 ohm resistor would be written as a 0R5.  A 50 ohm resistor would be 50R, or 50R0, depending on the resistor"s specified precision.     

PW

ADDED:

An alternate method of reducing wire related inductance is to use larger diameter wires or use parallel runs of wire.

In the 2" of wire equals 40nHy used above, paralleling two 2" lengths of wire will cut the inductance in half, or to 20nHY.  Paralleling two more wires, that is, a total of four 2" lengths of wire in parallel, will again halve the inductance, now totaling only 10nHY.

In fact, an infinite number of parallel wires would represent a geometric plane with a given thickness, so, in order to reduce inductance in the ground and supply circuits of high speed printed circuit boards (PC motherboard, etc) entire circuit board layers are dedicated as the ground and power planes with as much solid copper area as possible on these layers (six to eight layer circuit boards are very common because of this).  For the most part, these solid ground and power plane layers act as infinite parallel runs to reduce inductance to a minimum.


 

   
« Last Edit: August 24, 2012, 06:25:28 AM by picowatt »

mrsean2k

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Re: Testing the TK Tar Baby
« Reply #4683 on: August 23, 2012, 08:52:05 PM »
He started out the discussion with DC conditions before moving on to AC.  Whether or not she can understand and visualize the difference between the two is another question


That's what prompted me to comment really. That and the fact that .99 restricted the response to just answering yes to a summary in RA's own words, rather than stating the position in less ambiguous terms (but I suppose even Sisyphus fancies a rest now and again).

TinselKoala

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Re: Testing the TK Tar Baby
« Reply #4684 on: August 23, 2012, 09:47:33 PM »
And of course she has seen and commented upon my short video demonstration of a"measurement pitfall" using the simple Joule Thief circuit.

I show a dramatic difference in the scoped waveform, simply by moving the scope probe's reference lead to the other end of a 3" bit of wire in the circuit.

Her considered analysis of this video is... that it is faked in some way.

http://www.youtube.com/watch?v=KWDfrzBIxoQ

picowatt

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Re: Testing the TK Tar Baby
« Reply #4685 on: August 24, 2012, 05:33:13 AM »
Quote

And Poynty - here's another thing I've thought of.  The impedance is INCREASED - those Ohmic values INCREASE - as the frequency increases.  Conversely, it would be LESSENED as the frequency is slower.



Capacitive reactance decreases with frequency.  That is, the AC impedance ("resistance") of a capacitor DECREASES as the applied frequency increases.

A 1uF capacitor has a reactance of approximately 159 ohms at 1 KHZ.  At 1 MHz, it has a reactance of .159 ohms.



Inductive reactance increases with frequency.  That is, the AC impedance ("resistance") of an inductor INCREASES as the applied frequency increases.

A 1uHy inductor has a reactance of approximately .0063 ohms at 1KHZ.  At 1 MHz, it has a reactance of 6.3 ohms.



Magluvin

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Re: Testing the TK Tar Baby
« Reply #4686 on: August 24, 2012, 06:51:52 AM »

Capacitive reactance decreases with frequency.  That is, the AC impedance ("resistance") of a capacitor DECREASES as the applied frequency increases.

A 1uF capacitor has a reactance of approximately 159 ohms at 1 KHZ.  At 1 MHz, it has a reactance of .159 ohms.





But then, depending on the capacitor, there will be freq above 1mhz that the resistance/impedance will increase, again depending on the inductance within a particular cap.

I wonder if we were to make 2 caps, both using the same length and width plate strips, but we roll them a bit differently.

The first, we lay one strip on top of the other and we connect our leads to each strip at the same end of the stack of 2 strips, say both leads on the left end of the strip stack. We wont even roll these for this. Just strip capacitors.

The second cap strip stack, ;] , we connect our leads, one on each end. One lead is connected to the top plate on the left end, and the other lead to the bottom plate on the right end.

When a cap is charged, 'current' flow, in one plate and out the other, the arrangement of where we have our leads(the way in and the way out of the plates) must affect the level of inductance in the cap, due to which way currents flow in and out of the plates, while the plates are inducing currents in each other, depending on the flow of those currents.

If the leads are connected at the same end of the plates, currents should flow easily as they are in opposite directions. But leads on opposite ends of the plates, the currents flow all in the same direction, so inductance should be well present here.

Weird aint it.   So, with opposite ended, higher induction, maybe this kind of cap, say rolled, could receive a charge from a pulse of a primary coil magnetic field. Use a diode across the cap leads that uses the pulsed induction to take from one side of the cap to the other.
Then the charge will stay in the cap till taken. lol Now for discharge, use leads on the same end for least inductance.  Ive seen 4(2 on each end) lead caps, but Im not sure they are used this way.

I wonder. And Im about to drop. Sleeps

MaGs


TinselKoala

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Re: Testing the TK Tar Baby
« Reply #4687 on: August 24, 2012, 10:49:28 AM »
Electrolytic FETs.  Look! Polly Parrot squawks a new word, without the faintest clue as to what it means.

Capacitors....some capacitors are electrolytic .... FETs have capacitance.... therefore FETs are electrolytic.



Can't grasp the difference between a direct relationship and an inverse relationship... can't see that dividing BY one is different from dividing INTO one. Just wait until someone tries multiplying by one!

Well the writers of this sitcom are really scraping the bottom of the barrel now. Just start grabbing numbers and multiplying them, why not.


TinselKoala

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Re: Testing the TK Tar Baby
« Reply #4688 on: August 24, 2012, 10:51:15 PM »
Spam for lunch again!

Better stick to gin, Ainslie.

Magluvin

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Re: Testing the TK Tar Baby
« Reply #4689 on: August 24, 2012, 11:42:16 PM »
@All

I sort of thought this thread was going to fall on its sword.  Apparently not.  In which case perhaps it needs some more comments.  Here's this for starters.

The lament of the trolls

A pickle spent much of the day trying to say
That his size was most certainly measurable
While conductance was possibly part of that art
It was capacitance made that art pleasurable.

But reactance then came to be largely to blame
For his size that was somewhat dirisable
As the whole was revised and accordingly sized
And found to be ever divisible.

His friend who lived up there some many miles high
Explained that he had a solution.
But he factored the square of pi in the sky
Which compounded to abject confusion.

And the owl then decided to throw in the towel
As she tried very hard not to snigger.
For she knew that though small, Planck's constant was all
Of it yet most assuredly bigger.

And the point of this sorrowful dirge that I urge
You to hear in this gentle reminder
Is the brunt of the joke that I poke at this bloke
Is one needs to be cruel to be kinder.

And here some links for some required reading.
http://www.energy-shiftingparadigms.com/index.php/topic,2310.msg3138.html#msg3138
http://www.energy-shiftingparadigms.com/index.php/topic,2310.msg3138.html#msg3139
http://www.energy-shiftingparadigms.com/index.php/topic,2310.msg3138.html#msg3141
http://www.energy-shiftingparadigms.com/index.php/topic,2310.msg3138.html#msg3146
http://www.energy-shiftingparadigms.com/index.php/topic,2310.msg3138.html#msg3150
http://www.energy-shiftingparadigms.com/index.php/topic,2310.msg3138.html#msg3151
http://www.energy-shiftingparadigms.com/index.php/topic,2310.msg3138.html#msg3155

enjoy.


Hmmm, all the energy put into writing that. But still no testing. Ahhh, the leisure life. ;]

MaGs

mrsean2k

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Re: Testing the TK Tar Baby
« Reply #4690 on: August 25, 2012, 11:55:14 AM »
@YSW


Don't you find it remotely humiliating to come here under the paper-thin pretense of being someone else, posting in your own defense, and then lying about it to your own followers on your own website?

picowatt

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Re: Testing the TK Tar Baby
« Reply #4691 on: August 25, 2012, 03:52:52 PM »
From over there:

"By the way - Poynty Point.  I see that Harvey or 'piowatt' as he prefers to be called - has denied this statement of mine.
Quote from: Rosemary Ainslie on Yesterday at 04:40:59

Quote

    And Poynty - here's another thing I've thought of.  The impedance is INCREASED - those Ohmic values INCREASE - as the frequency increases.  Conversely, it would be LESSENED as the frequency is slower.


He's WRONG.  Do let him know."


REALLY?

Is she saying that she disagrees with my statement that capacitive reactance decreases with frequency and inductive reactance increases with frequency?  I sure would like to see some supportive data to her "argument".

Possibly she can provide the "correct" reactance for a 1uF cap at 1KHz and 1MHz?   

.99, please do read my recent posts and indicate where I am wrong...

Flabbergasted...


(And yet again, I am not Harvey.  She continues to wage her battle with him against the wrong person... )





   

 

poynt99

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Re: Testing the TK Tar Baby
« Reply #4692 on: August 25, 2012, 04:11:56 PM »
PW,

Rose didn't mention which impedance she was referring to, so I stated the facts once again for her. I empathize with your frustration.

picowatt

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Re: Testing the TK Tar Baby
« Reply #4693 on: August 25, 2012, 04:30:54 PM »
PW,

Rose didn't mention which impedance she was referring to, so I stated the facts once again for her. I empathize with your frustration.

.99,

From her preceding posts, she was apparently discussing the MOSFET capacitances ("electrolyte" and all...).

She also appeared to be confusing the effects of capacitive reactance with inductive reactance.

Thanks,

PW



mrsean2k

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Re: Testing the TK Tar Baby
« Reply #4694 on: August 25, 2012, 05:58:59 PM »
Rosemary,

You should be more circumspect in the allegations you make when you lob them in my direction. I don't place the same value on anonymity as other, more patient people you toothlessly rail against, so I'm not anywhere near as constrained in my possible response.

The offer has been made to you, on more then one occasion, to select a specific file that you claim has never been made public, and for the original public source of that file to be disclosed to you. You have never taken up this offer. Now why would that be?

The simple answer is that it is so hard for you to keep track of your lies and changing story that you have no idea what you have or have not posted publicly.

The telephone number you posted in full public view on you own forum for instance. The actions consistent with someone clueless about security and privacy in general.

There is no need for me to exaggerate your behavior to paint you as a fool - you confirm your own ignorance of even basic arithmetic almost every time you post.

S