Testing the TK Tar Baby

[Rosemary Ainslie]

Here we go picowatt.  I see now what you're getting to.

When the Fg output is a negative voltage,  the negative voltage applied to the gate of Q1 turns Q1 off.  Simultaneously, a negative voltage is applied to the source of Q2 (the source of Q2 and gate of Q1 are connected and therefore always the same voltage).  When the negative voltage from the FG is applied to the source terminal of Q2, Q2 turns on (making the source terminal of Q2 negative with respect to its gate causes Q2 to turn on) .  However, as Q2 turns on, current flows thru Q2 and thru the FG.  This current flow thru the FG causes a voltage drop across the 50 ohm Rgen in the FG.  Because of this, the voltage as measured at the output of the FG, when its output is a negative voltage, can only be the Q2 turn on voltage for any given amount of current passing thru it.  Esentially, in this mode, Q2, in concert with the 50 ohm Rgen, acts as a current regulator and Q2 is therefore biased into a region of linear operation.  Ibias, that is, the DC current that flows thru Q2 and the FG when the FG output is a negative voltage, is expected to be in the 40-250 milliamp range and is determined by the FG open circuit negative voltage, the 50 ohm Rgen, and the threshold voltage of Q2 (Ibias has been measured and confirmed by both .99's simulations and TK's empirical measurements).  As one can clearly see from the 'scope captures, regardless of the open circuit negative voltage of the FG, the FG output is always at -Vth due to the voltage drop across Rgen from the bias current flowing thru Q2 and Rgen.  As the FG output is made more negative, Ibias is increased and the voltage drop across Rgen also increases.  The FG output, therefore, when outputting a negative voltage, can only be the source to gate turn on voltage required for a given Ibias.  (one would have thought that this "clamping action" that is obvious in all 'scope captures when the FG is a negative voltage, regardless of the FG offset settings, would have caused "someone" to wonder why.  And clearly it is due to the Vdrop across Rgen when Q2 bias current is flowing thru the FG)

This is balderdash.  From inception to conclusion. 

Rosie Pose.

[picowatt]

picowatt

I started reading your post and just got disheartened at its length and obscurity.  Forgive me - if you're depending on my reading it I, unfortunately, just don't have the appetite. I have a very short attention span and absolutely no interest in your opinions.  Unless it was not intended for my readership.  In which case all is dandy.

Rosie Posie

I do not care one way or the other if you read it.  It was intended as a quick synopsis for readers here related to errors in your papers and your misunderstanding of your circuit's operation.

Possibly your short attention span is precisely why you have never learned how FG's, o'scopes, and your circuit operate.

I assure you, my description of your circuit's operation is precisely accurate, and not "opinion".  You would be very hard pressed indeed to find anyone competent in electronics that would disagree with anything stated in my post.

If you think I have made opinionated errors, then why not take the opportunity to ridicule me and copy/post it at your "other site".  Ask .99 if anything in my post is even remotely inaccurate.

Rather than argue and dispute, this is a perfect example of yet another learning opportunity for you gone to waste. 

However, other readers may find it rather enlightening.

[Rosemary Ainslie]

I do not care one way or the other if you read it.  It was intended as a quick synopsis for readers here related to errors in your papers and your misunderstanding of your circuit's operation.

Possibly your short attention span is precisely why you have never learned how FG's, o'scopes, and your circuit operate.

I assure you, my description of your circuit's operation is precisely accurate, and not "opinion".  You would be very hard pressed indeed to find anyone competent in electronics that would disagree with anything stated in my post.

If you think I have made opinionated errors, then why not take the opportunity to ridicule me and copy/post it at your "other site".  Ask .99 if anything in my post is even remotely inaccurate.

Rather than argue and dispute, this is a perfect example of yet another learning opportunity for you gone to waste. 

However, other readers may find it rather enlightening.

LOL.  I rather hope not.  It would be sad to find you effectively misinforming anyone at all.  And that seems to be all you can manage.  And NO.  I will not have your nonsense polluting our little forum.  We're trying to keep things topical and scientifically dependable.

Rosie Pose

[picowatt]

LOL.  I rather hope not.  It would be sad to find you effectively misinforming anyone at all.  And that seems to be all you can manage.  And NO.  I will not have your nonsense polluting our little forum.  We're trying to keep things topical and scientifically dependable.

Rosie Pose

This is not misinformation, nor is it nonsense.  And if you truly believed that, you would take that post to an EE and confirm that it is all nonsense to support you position.

But you will not, for you fear it is all true.  And what would that mean?

[Rosemary Ainslie]

This is not misinformation, nor is it nonsense.  And if you truly believed that, you would take that post to an EE and confirm that it is all nonsense to support you position.

But you will not, for you fear it is all true.  And what would that mean?

Not actually picowatt.  I'd be embarrassed to show anyone at all your ridiculous proposal that Q2 turns ON with an applied negative signal from the function generator.  It's ABSURD. 

Rosie Pose