Testing the TK Tar Baby

[picowatt]

Rosemary,

You do and have twisted my words.  When discussing FIG3, one of your responses was with regard to me being wrong about 12volts being indicated at the shunt.  I never said there was 12volts indicated at the shunt, yet you try to make a point using that as a response, as if such a statement were actually made by me.

As well, you continue to attempt to justify your tirade over my use of the word "review", which appears to me as only a game being played over semantics.  I have no interest in playing that game.  If you reread my post where I used the word review, I said 'by anyone attempting a replication or a review', not anywhere stating that I was doing a review, other than as required for a replication.  It was my understanding, however, that you have attempted or were going to attempt to publish your papers, during which someone woud surely have done a "review" of some kind.  I do not believe your tirade towards me over a simple word was justified.     

Another perfect example of twisting words or putting words in my mouth, is when I stated a few posts back that "a negative voltage on the source of Q2, as applied by the function generator, allows current to flow thru Q2 and the FG."  You respond with "You state as fact that the current is flowing through Q2 and the functon generator resulting in a negative voltage".  To me, the two statements are far from the same.  I did not state "resulting in a negative voltage".  The two statements, my original and the one you claim I stated, are materially very different.  Possibly you  believe the two statements are similar and see no difference, but from a technical point of view, I assure you, they are not at all similar.

I have over the past few weeks looked at other sites and threads going back to your COP17 circuit gleaning data for a replication.  It seems the battle between you and many others has some very lengthy roots.  I fully disagree with the need for anyone to use the abusive language that so many of those threads (and even this one) seem to erode and collapse into.  I do not fully understand why tempers are apparently lost or why such abuse is allowed by moderators or site hosts, however, I am not here to moderate attitudes or get involved in long standing battles between anyone.  If such abuse is ever directed towards me, I will excercise my right to just walk away. 

Although I enjoy a good discussion, I have no desire to become involved in emotional arguments with or between anyone, and this post of mine is exactly the type of post I have no further interest in creating,.  It involves a discussion very far from anything of a technical nature or interest.

So again, I just wish everyone would/could just "lighten up".

The "likes of me" indeed,

PW



           

[TinselKoala]

@PW:
You've said, several times as you point out, that a 50R might be used in the series line from the bias source. Of course I tried this right away when using the (nearly flat) 9v battery and it's there on the board, two 1/2 Watt 100Rs in parallel. Ohm's Law still seems to apply, though... to get the oscillations a minimum of about 15-20ma seems to be required and the amplitude and distortion of the oscillations still depends on the current... which depends on the voltage. So with the 50 R in series, one needs more voltage from the pot or power supply to attain the required current.

Right?

With the flat 9v the 50 R is too much resistance and the current won't go over 40 or 50 mA and the oscillations remain small. That's why I've made it easy to use, or not to use, this resistor. It's been there for several days now... but it's a series resistance, and with the fixed 10R at the pot wiper (if the pot and battery are used) it's just too much for a weak battery, or a 5 V supply, to push through. But sure.... if I hook the Elenco supply directly up to the circuit (why not?) I use the 50 R.... just because. The Elenco is short-protected of course but why take a chance? Regardless of the 50 R or not, the main battery is still in series with the bias supply.

I also purchased a NOS DC-DC converter at the surplus house. 12 VDC in, 5 VDC CT out ( Stevens-Arnold WF 12S05/1000Z). But.... buggers, they had no data on it at the store, and when I got it home I found that it has common grounds/negatives for both sides. This is different from some other DC-DC converters I've used in the past and of course makes it unusable here. Also, it doesn't even work to make oscillations in the "correct" config, powered from an external source,  because it doesn't want to source enough current. It works just fine in the "positive" gate drive mode to turn the mosfets on hard when its + is connected to the + location on the board -- but that takes a minuscule current at 5 VDC.

[picowatt]

TK,

Bummer regarding the non-iso grounds on the DC-DC converter.

Personally, I would lose the bias pot and just use the FG or pwr supply and the 50R while attempting to maximize oscillations at lower Ibias currents.  If lower currents can be utilized, Vbias can be decreased for a given source resistor.

I believe you said osc just begins at 25ma or so, I think I would experiment with the circuit at that Ibias and play around with more battery wire length etc. to see if the amplitude of the oscillations can be increased at that lower Ibias.     

Do your waveforms at the source of Q2 resemble those in FIG4 or FIG 5 of the first paper?

PW

[picowatt]

TK,

If you were going to scribble on your scope face, which around here would be cause for a good "strapping down", I would rather have had the zero baseline and V per division indicated!!

So, please indicate verbally or otherwise.

PW

[TinselKoala]

TK,

If you were going to scribble on your scope face, which around here would be cause for a good "strapping down", I would rather have had the zero baseline and V per division indicated!!

So, please indicate verbally or otherwise.

PW

It's Glass, not plastic, so it is quite easily cleaned,  and it's not a measurement... it only _relates_ to a measurement.

I just couldn't help myself when I saw the shape. Zippy the Pinhead is a hero of mine from waaay back.

The amplitude of the oscillations is indeed extremely unstable, as you might imagine, and does not only depend on the inductances but also on the capacitances between the leads. I've twisted up the cable sets to the mosfets and have gotten more stability without killing the oscillations but I can always untwist them down again. When I do, just moving my hands around or touching the mosfet heatsinks will affect the amplitude of the oscillations.

Don't worry, if I make a measurement I'll put in the references... don't I always?

My Elenco seems to be putting some hash on the bias right now.... so I guess I'll have to dig out the HP bench supply and see if it's any quieter. I'm telling you, this silly circuit is a component destroyer.... her COP>17 circuit was too, from the HV spikes it could generate.