another small breakthrough on our NERD technology.

[TinselKoala]

@MH: the FG leads can be clearly seen in the shot .99 posted to show me the heatsink. The positive lead is the red alligator clip and the ground lead snakes over behind the probe and connects to the common ground bus at left.
In other words, of course you are right about the connection used in the video. And it's contrary to the circuit schematic used in the video, reproduced below, which doesn't show the FG ground at all--- AND shows a 72 volt battery pack. Don't try this with a single mosfet unless you are properly heatsunk and even fan-cooled... or you have a lot of mosfets.

[Rosemary Ainslie]

Rosemary:

I had another look at the clip and I realized that at the very beginning of the clip that you can clearly see that the function generator is grounded to the common grounding point for the probe grounds, which is the battery ground.

So now we are looking at another scenario:  When you wrote your two papers Rosemary you realized the mistake with respect to the grounding issue for the function generator.  It would not be correct to show the function generator bypassing the current sensing resistor because the current sensing resistor is supposed to be "pure" and account for all of the battery current.  Therefore you intentionally changed the simplified schematic diagrams in the papers to show the "negative" signal from the function generator connected before the current sensing resistor, even through you knew that this was not really the case.

Is the scenario that I just outlined above true Rosemary?

The simple fact is that you probably thought that it was a minor and benign change that nobody would notice and it would not really make any difference - or so you thought.

But the fact of the matter is that it makes a huge difference.  In the correct configuration as per the actually built device you have an AC-coupled signal going to the current sensing resistor.  There is no DC path at all in negatively offset oscillation mode.

It wasn't a benign change that nobody would notice, it's a complete and total screw up.

MileHigh

MileHigh I've answered from the get go.  From our very first post that Poynty made on this forum and my previous thread.  Pay attention.  Our demonstration was only to show that there was a coincidence in numbers between the Tektronix and the Le Croy.  This because the Tektronix is NOT grounded.  Therefore grounding issues related to incorrect readings could be obviated.  This is widely denied - but I'm not about to engage in yet another argument about that.

NOW.  To accommodate 8 probes and their respective ground terminals - and the applied signal from the function generator - we simply ran out of space.  Therefore, for the purposes of that demo we simply hooked the signal generator's probe to an available point which was 'behind' the CSR and in directly line with the battery negative.  We KNOW that it makes no significant difference to the values of the current.  We PROVE that it makes no significant difference in the tests detailed in our paper.  This because the CSR is NOT embedded in that loop for any of our tests that are included in our paper.  May I impose on you to drop this.  I assure you the tests for our paper ONLY have the CSR in line with the negative terminal of the battery.  NOTHING ELSE.  And - in point of fact, our signal probes are typically applied directly to the two gates of Q1 and Q2 respectively. 

And notwithstanding your assumption about this - it most certainly WAS, at it's MOST - a  benign change.  When I get the go ahead I'll be able to show you this.  There is very little difference between the values on the CSR regardless of the position of that ground terminal of the signal supply.

Regards,
Rosemary

[Rosemary Ainslie]

There is somewhat of an enigma about this "high heat mode."  Assuming that you are looking at a "correct" data capture where the Q1 MOSFET is functioning then you have the gate drive high and the CSR shows significant current flowing through the circuit.  There are no oscillations so I have to assume that the battery voltage is stable.

So during this part of the cycle you are looking at a 100% conventional setup, a single MOSFET, Q1, switches on and DC current flows through the load resistor and the MOSFET.  Certainly there is a likelihood that the MOSFET could be overstressed and is dissipating more power than you would like it to, but everything is 100% conventional and the DSO should record positive power during this phase.

Then if you go into oscillation mode and the other four MOSFETs start to spasm, isn't the implication that the DSO is recording enough "negative power" to completely compensate for the positive power recorded during the Q1 ON phase?

Not entirely MileHigh.  Each negative oscillation is matched by a positive.  And if you look at the math trace - then there's more returned to the battery during the oscillation phase than was delivered in 'on' phase.  But the actual question is WHERE does that positive half of each oscillation come from.  Which goes back to our early quarrel.  You claim that it can pass through the signal generator straight to the battery ground rail.  I don't buy that argument.  It's most easily refuted by the fact that we can get precisely the same oscillation from a 555 switch.  But there are more cogent arguments yet.  I just haven't got the patience to go through them again.

And I think I've answered your other points in my previous post.

Regards,
Rosemary

[Rosemary Ainslie]

Good morning, Little Miss MOSFET.

And good morning to you too TinselKoala.  But we're actually romping into our early evening - which puts me way ahead of you. 

Rosie Pose

Pretty picture by the way.  Not sure you've done my figure justice.  But the face is good.

[TinselKoala]

An item of possible interest to some of us.....
http://www.youtube.com/watch?v=FURkoitGRwI


And there seems to be something else very strange on that channel..... a fresh alt.snakeoil Video Report.