Testing the TK Tar Baby

[picowatt]

Guys - picowatt seems to think that he can promote those same arguments that have already been disproved.  I've said it before.  This entire thread is INFINITELY circular.  I think I'll pass on arguing it again.  Just know that it's wrong.  In every sense of the word.And this latter part of his post needs PROOF.  Not ALLEGATION.  I can EASILY disprove it as I will DEMONSTRATE that the MOSFET IS NOT BLOWN.  And then I will PROVE that the voltage changes when we apply the AC coupled value. 

Regards,
Rosemary

PW

Nothing circular at all, just facts based upon the presented data.  If you want to prove something, demonstrate another test where +12 is applied to the gate of Q1 as in FIG 3 and where there is no indicated current flow.  If Q1 is both connected properly and functioning, it can't be done.

Q1 must pass current if +12 volts is applied to it's gate.  Surely you must agree with that. 

PW

[PhiChaser]

Hello hello Rosemary.
Got any new math for us today?
No??
Hmmm... Why not??
Zipons got your tounge??

PC

[MileHigh]

PW:

Thanks for that information. My guess is that you are a very senior or retired analog/RF engineer with a vast amount of knowledge and experience under your belt.  The breadth of your experience probably spans the 60s through the 2000s.  And of course if you worked during the 60s that means your experience actually encompasses the technology of the 40s and 50s.  Therefore you have upwards of 70 years worth of tech experience under your belt.  Pretty awesome.

MileHigh

[picowatt]

Guys - picowatt seems to think that he can promote those same arguments that have already been disproved.  I've said it before.  This entire thread is INFINITELY circular.  I think I'll pass on arguing it again.  Just know that it's wrong.  In every sense of the word.And this latter part of his post needs PROOF.  Not ALLEGATION.  I can EASILY disprove it as I will DEMONSTRATE that the MOSFET IS NOT BLOWN.  And then I will PROVE that the voltage changes when we apply the AC coupled value. 

Regards,
Rosemary

And the PROOF you claim to need is right there staraing at everyone in the FGG 3 'scope shot in the first paper.

All readers are advised to have a look for themselves (it is also the first figure in the new blog posting TKprovided a link to recently).  During the positive portion of the FG cycle, the indicated voltage is approx. +12 volts.  If the FIG 3 represents a test performed with a circuit connected as in the schematic of the first paper, Q1 must turn on at that applied voltage.  However, the CSR trace demonstrates no significant current flow during that period, so either Q1 is disconnected or damaged.

In FIG 5 of the first paper, less than +12 volts is applied to the gate of Q1 during the same period and the CSR trace readily demonstrates current flow as would be expected.

PW 

[Rosemary Ainslie]

You have "explained" nothing.

More misquoting I see.

The source of Q2 is connected to the negative rail (or CSR) through the function generator.

Not actually picowatt.  That's your latest much needed qualification.  And you're still wrong.  Self evidently.  And we will PROVE this.  It's a very easy test

The gate of Q2 and the source of Q1 are connected to the non-battery end of the CSR and can therefore NEVER be at any potential other than the potential indicated by the CSR trace, which is near ground potential, particularly with respect to DC (below the Vgs required for turn on).  When the FG output is a positive voltage, a positive voltage is applied to the gate of Q1 and Q1 turns on (except as noted in your FIG 3 where the Q1 is not functioning).  Q2 is off during this phase.

And here your sense is lost in all that 'hand waving'.  IF the function generator is NOT functioning - as you put it - then NOR does it function in TK's Tar Baby REPLICATION.  Which both he and we can manage without even using the function generator.  Explain THAT if you dare. 

When the FG output is a negative voltage, a negative voltage (i.e., more negative than the batt-) is applied to the source of Q2 and a DC current flows through Q2 and the function generator to the CSR (or batt- if that is where the FG common is connected, as in the March video).  Q1 is off during this phase.

NOT actually.  When the negative voltage is applied to Q1 - then the positive is applied to Q2 - WHICH WE WILL DEMONSTRATE.  And the battery supply can be negative 72 volts.  Therefore is it NOT 'more negative than the batt negative'. 

The DC current flow thru Q2, that is, Ibias, is limited to around 200ma plus or minus 50ma or so by the action of the applied negative voltage from the FG, the Rgen=50R, and the turn on voltage of Q2, which biases Q2 into a linear region of operation.

Then you will need to argue how we read a negative voltage that varies between 4 amps and upwards.  And how it is that Poynty cannot simulate the oscillation with 50 Ohms resistance from the function generator.  Among many OTHER glaring contradictions to this 'argument' - if such it is?

Rosie Posie