Testing the TK Tar Baby

[Rosemary Ainslie]

picowatt


I'll get back here - when I've finally addressed that penultimate post to me.  But for now this statement...

With regard to DC, Q2 does not turn on fully.  It is being biased into a linear region of operation.  Q2 will regulate the DC current flowing thru it in concert with the FG negative voltage and the FG's internal 50 ohm resistor such that the DC current flowing thru Q2 when it is biased on will be limited to 200 milliamps more or less.  This current is referred to as "Ibias".

This amount of current would produce only +50 millivolts more or less of voltage at the CSR.  At the 'scope settings used, and with the oscillation masking its view, this 50 millivolts would be difficult to see.

Additionlly, if the FG signal ground is connected to the battery side of the CSR, the Q2 DC bias current would not be indicated at all by the CSR trace, as the bias current would not be passing thru the CSR.

If the LeCroy Wavejet is NOT able to accommodate those +50 millivolts - then it is NOT performing according to it's rating.  NOTHING is masked in that oscillation measurement across the current sensing resistor.  And I know perfectly well what you mean by Ibias.  Are you implying that I'm that stupid? And are you STILL inferring that the oscilloscope measurements can't be relied on?  Because that excuse is getting TIRED.

Again
Rosie Posie

Qualified the highlighted.

[picowatt]

Thanks, that is what I figured as well.

So, if all goes well we have another play date on Monday.... if I get my radiator back from the shop tomorrow as scheduled. For that one Tar Baby will have freshly charged batteries, five of them, and I'll be sure to use DC coupling on all traces... as appropriate.

If you could please remind me before then of some of the (short, easy) tests that you suggested I do with that scope, I'd appreciate it, and perhaps I'll be able to perform them, if Tek's momma isn't using it for (redacted) at the time.

Unfortunately, unlike the old LeCroy that I demoed some time ago, this Tek only seems capable of displaying a single math trace, but it can do fairly complex functions and nested algebra on that one trace.  Of course I still haven't read the manual nor have I pushed all the buttons or turned all the knobs, so there might be hidden functionality that I'm not aware of. For example there is this whole "wave inspector" thing that could be useful if someone only understood it.

TK,

Do you have time to attach some caps across your batteries to eliminate AC at the batteries?  Place the caps between the most negative terminal and the most positive terminal.  Use whatever caps you have with sufficicient V rating and as many as you need to remove all AC when you scope the BATT+ terminal. 

Also, if you want to use the ground point at your motherboard for all probe grounds, it might be necessary to add additional parallel runs of wire from the BATT- to the motherboard to reduce the BATT- lead inductance (or shorten the BATT- lead).

You'll have to analog 'scope across the batteries before you leave to make sure the AC is been fully removed from the batteries by the caps and that the oscillation, as measured at the motherboard BATT+ is not affected or squelched.  If it is, add a bit more wire length between the BATT+ and your motherboard to get the oscillation going again (to replace the inductance lost when te batt interconnect wires were bypassed with the caps).

If this works without affectig the osc to any degree, you should be able to scope at the BATT+ and see amooth DC, and alternately you should be able to scope at the motherboard BATT+ connection and see the unchanged oscillation.  You would have to work on this a bit tonight to ensure you can maintain the osc with the BATT bypassed.  Again, several feet of wire can be added between BATT+ and the MB if needed.

You should then be able to make a measurement using the motherboard connection point as your Vbatt probe point with its AC signal riding on the DC and see the neg mean pwr.

A second measurement then taken with the Vbatt probe at the smoothed batt+ terminal should then indicate a pos mean pwr.

Ask more if this is not clear. 

I can't believe you are going to do all that driving again.

If you do not have time for all this, no problem.

PW

[picowatt]

picowatt.  This is the post you refer to.In the first instance you 'IMPLIED' that your analysis related to the 'offset' reading of the LeCroy was ENTIRELY representative of the the zero point positioning of the signs against the X axes center graticule - as it relates to zero.  And what I TOLD you REPEATEDLY - is that this zero reference needs to be qualified against the 'coupling' that is manually applied to the voltage reading.  Therefore is there no relevance related to representation of the voltage across the Gate of Q1. Remember?  You said either the MOSFET had blown - OR - the Le Croy measurement was wrong. Well that OPINION is wrong.  There is no resulting SKEW that also results in an incorrect math function as you INFERRED.  Nor is there SKEW resulting in a MISREPRESENTATION of the zero crossing line across the current sensing resistor.  Nor is there SKEW resulting in a MISREPRESENTATION of the battery voltage.  Nor does the voltage across the Gate at Q2 represent the entire picture.  It needs 'qualification' against that coupling.  And further qualification against the the offset of the function generator.  And as an 'expert' in the art of reading an oscilloscope - you should have KNOWN this.  Instead of which, let me say this again, you DECLARED that either the MOSFET had blown.  OR that there was a measurement's error.  You were  and are WRONG on both counts.   Where I erred was in my poor efforts to explain this.  But you do and did understand me.  And you are and were pretending not to.  In the same way that you pretend that preschoolers can capably handle a solder iron - or that they can read, write and do THE MATH - at an average and adult level competence.

Then you state...This is like MileHigh's proposal that the best way to evaluate the oscillation is to remove it.  IF you apply a path for that counter electromotive force - away from the battery - then it will not be advantaged by the potential difference of those batteries.  I would refer you to our introduction, discussion and conclusion in the second part of our two-part paper.  You prove NOTHING by taking away the very property that we rely on to generate the oscillation.  The argument is as good as saying water flows downhill.  I can disprove this by putting a mountain in its path.  Then within a certain limited supply of that water - I will PROVE that it no longer flows downhill.

Here is the effective paragraph from that paper that relates to this.
Effectively, therefore, the battery primary supply represents the only component on the circuit that has an intrinsic charge imbalance. Therefore at each zero crossing, which is the point when the current entirely discharges the potential difference across the circuit material, then the voltage across the battery moves to its average voltage which, unlike the circuit components, is always greater than zero. Therefore too, the CEMF will add to or subtract from that battery average depending on the applied voltage and direction of current flow. This, in turn, thereby imposes a greater potential difference at the battery than its rated capacity. [/font]

Which following a logic that is REALLY skewed - you then state...in the hopes of endorsing the 'spin' that you rely on - so heavily.   There is no-one member or reader here, that also reads this thread with any level of impartiality - or even scientific detachment -  that will EVER believe that you'd be 'SORRY' to find reason to dismiss our claim.  I"ll move onto your last post  to me hereafter.   

Kindest regards nonetheless
Rosie Posie

Rosemary,

What you are saying regarding the 'scope and offset is true for the Tek, it operates differently than the LeCroy.  I do not believe the same can be said for the LeCroy.  I will call LeCroy in New York on Monday and put this to rest for good.  At this time I stand by my assertion regarding Q1 in the figures discussed.

As for your discussion about SKEW I have no idea what you are talking about.  I specifically stated I did not believe skew had anything to do with any error.  Please read what I write and quit putting words in my mouth.

As for the rest of your rant, I suppose you are calling me a liar.  I will just say you are wrong and if this is to be your tack, it is far from professional or supportive of you claim.

If you rely on "that property to generate the oscillation", then I suppose you will agree that by bypassing the batteries the oscillation must cease.  What if the oscillation can be made to continue with the battery bypassed?

The test I propose may prove nothing to you, but it would prove something to me.

Do you propose that the battery voltage as indicated by the battery trace represents the true battery voltage?  Do you really believe hundreds of amps are flowing to and from the battery?

Is it not more logical to believe that the inductance of the interconnect wires to and between the batteries are of a relatively high impedance with regard to the frequency of oscillation?

Do you believe that inducutive reactance is real or just imaginary?

PW

[TinselKoala]

@PW:
It's perfectly clear, thanks, and it won't take too much time at all, and I have lots of caps big and small. I could put 40,000 uF across the 60 volt stack with no problem if necessary, and I can sub a 70,000 uF cap for a single battery as Mile High has suggested, if necessary. And yes... I'm aware of what 40,000 uF at 60 volts can do if it's mishandled... knock on wood. I don't want any batteries or caps catching fire on ME.

But Ainslie has a point too, and that's by removing the oscillations we are also removing any effect they might have on the battery. So of course we'd get a positive power flow using measurements from the battery, since the beneficial oscillations are being "captured" somehow by the filters and never get there. This is also the objection I had to the validity of the LEDs of Doom test: putting a diode, even a forward-biased one, would seem to block the oscillations or otherwise affect them, and so might block the beneficial effect if there is one.

So shouldn't I put my filter caps in an explosion shield, in case they charge up past their capacity and explode?

I'm sure you've blown up a capacitor or two in your time. Those little electrolytic cans are especially neat when they blow: I've seen them eject the entire roll of electrode material like a party cracker firework thing.

But then there's the other special pleading, hand-waving explanation: the oscillations and the battery are a system. Both need to be involved for any special effect to show up. So if the oscs are prevented from reaching the battery maybe there's no possibility of OU anywhere, not even in the filter caps.

So, other than proving that if you prevent the oscs from reaching the battery, you don't get a negative mean power product .... what does the test intend to test? Is it of anything more than "academic" interest?

[picowatt]

Rosemary,

Please keep in mind that a great deal of the current discussion is with regard to whether a neg mean pwr measurement as indicated on a 'scope can be relied upon as an indication of, or proof of, overunity or a COP>1.

Do you believe the neg mean pwr measurement definitely proves your circuit is COP>1?

PW