Testing the TK Tar Baby

[TinselKoala]

Oh... I almost forgot. Heating the load nicely.

(I think the EXIF data comes along with these jpegs, so you can see that I'm shooting these frames fairly close together in time, just minutes or seconds apart.)

[poynt99]

Rosemary,

I know you addressed this question to .99 but let me also clarify.

There has been many different opinions about your circuit "floating" on the Internet. The only way to make
sure to get the correct circuit analysis is to do actual measurement on the circuit and compare those
measurements with some theoretical analysis. That is what I'm trying to do. I'm also engaging .99
in this because I know he is a very knowledgeable person.

One of the "myths" that have been put forth numerous times is that the function generator is adding
power to the circuit. And, yes, that is partly the truth. But at the positive part of the function generator
cycle, the added power is burnt as heat in the MOSFET and DOES NOT ADD TO THE RLOAD.

In the negative part of the function generator cycle we have current flowing OUT of the switching circuit and this energy is BURNT OFF AS HEAT IN THE INTERNAL 50 OHM OF THE FUNCTION GENERATOR and DOES NOT ADD ANY POWER TO RLOAD. By doing the BIAS analysis I have found that there is NO WAY the function generator can ADD any power to RLOAD!So all posters, including myself, got it WRONG when we assumed that the function generator could add energy to to RLOAD. The only person that got it right was YOU, when you said (in a non technical way) that the function generator does not add any power to the the load resistor.

This is WHY I do my circuit analysis, to find the truth about the circuit on how it works.
GL.

I know you made subsequent posts which roll back the "certainty" espoused in this post, but this is silly GL. No one that made the assertion about the FG in negative mode is wrong. The "negative bias" drawing I made clearly shows the two supplies in series-adding, so how is it possible that either supply can NOT be contributing to the power to ANY component ALSO in series?

I think you jumped the gun again.  Your test will prove it.

[TinselKoala]

The more I think about it the more I realize that SCRN0235 is the critical bit of data that nails the lid on.

Events must have transpired just as I conjectured. She was happily tuning away, hit upon this mode shown in 0235 and had high heat in the load !! Surprise surprise ! Take some scopeshots, twist knobs.... and by the time things settle, one mosfet is blown, passing no current, and yet the load is still plenty hot. Eureka! We've discovered Free Energy !

Please... a careful analysis of this scopeshot is very important. Consider the DC power during the ON gate pulse, and apply the duty cycle to arrive at an average power level which does not even include any contribution from the oscs. THen if you like add some for the oscs. But DO compute the DC power level.

Got to run, real life intrudes. But seriously, folks... this shot and the ones immediately after it, combined with Ainslie's "analysis", contain the entire experimental case and blow it totally out of the water.

[poynt99]

.99,

>>>The reason for the difference between Q2 present and Q2 absent, is because the RDsON state of Q1 changes in each >>>case. In other words, the bias condition of Q1 changes.

I agree that the bias situation is different in the two cases but it does NOT change that fact that the MOSFET
is biased fully ON at each case and the GS voltage is +12 Volt in one case and +7 Volt in the other.

The RdsOn starts at very high Ohm when there is no positive voltage on the Gate (ref. to S). The RdsOn then
go down in Ohm when we increase the G voltage. But at some point the RdsOn will NOT go down anymore
because we have reached the saturation of the MOSFET and the RdsOn have reached the data sheet RdsOn of 1.6 Ohm.
It will not go lower than that. So in my case the linear region of the MOSFET current control ends at approx. 6 Volt.
ALL voltages on the G above that voltage will put the MOSFET into saturation.

GL,

From your measurements, the MOSFET RdsON isn't quite1.6 Ohms. The equivalent RdsON is actually 6.46V/1.83A = 3.53 Ohms.

Take out Q2 and re-measure V_DS. Then re-calculate the Rds using 1.94A.

[MileHigh]

TK:

You are definitely excited about something.  Are you suggesting that with a 50% duty cycle and six batteries in series the MOSFETs will blow?  That this is beyond the absolute maximum ratings for the part so it's inevitable that, "She's gunna blow!?"

Rosemary:

WHAT discussion?  I keep hoping for some kind of SKILL or some kind of relevance.  But it seems that my hopes are likely to be still born.  WHY do you think MilesOfPurePretension - that I took the trouble to advise you to correct your GROSS and ELEMENTARY errors in power analysis.  It's PRECISELY because I want our readers to think that there's some skill and therefore some relevance to ANY arguments that you propose.  When  you  parade this level of absurdity - then with respect - there is NO reader who will take you or this subject seriously.

You make another totally asinine grotesque display like this again and I will respond.  I don't know how you can even face yourself in the mirror.  You didn't even understand what I was saying and to see you get so ghetto is absolutely gross.

And I will remind you that the absolutely shocking thing about you is that after 10 years, you still cannot articulate what energy and power are properly:

Unfortunately our Standard Model has already determined the basis of wattage analysis.  Power equals the volts over time, x the amps over time.  You're SKEWING the facts.

Lo and behold, we must have tried about 50 times to explain energy and power to her and poor hapless Rosie Posie fails yet again to get it through her thick skull.

Let's not play any games here Rosemary.  You are clueless with respect to electronics and energy and it's abundantly clear that you are unable to learn.  So it's almost a case of you being "along for the ride" right now and certainly it will be the case if you ever actually follow through and do the dim bulb testing.  You are unable to do it yourself and are almost a helpless baby.  That is the reality of your situation.

MileHigh