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OK, let us analyse these archeological remains of "Golden Age". Part I

First, I note the date of this non-peer reviewed article: 1980...
I begin by part one.
The tantalum capacitor test shown is irrealistic, and does not address the cause of this distortion, which is due to bad design, as shown below.
A tantalum capacitor (furthermore from the '70s: military types T101, T110 for example) is an electrolytic capacitor, which means the tantalum anode is surrounded by an electrolytic solution (which means ions can move in. When subjected to a negative voltage above tantalum vs cathode material's electrolytic voltage (about 2 volts), it frees H+ ions and builds up a tantalum sesquoxyde layer, which is an insulator, stops the electrochemical reaction, and then acts as the dielectrics layer in a capacitor.
Once built, it stays as it is, does not change its width, and so, the resulting capacitor is rather stable. But, if you apply an invert voltage in the range of the electrochemical potential, (2 volts, as I said above), the dielectric layer begins to react and to give back metallic tantalum. At the end of the process, the dielectric layer will soon disappear, and the capacitor will not be a capacitor anymore, but a resistor of a few ohms.
To dissolve back the sequioxyde layer to metal takes in the range of a second.

So, now, if you create across the capacitor a AC voltage at 35HZ (like done in the article)and around 2V, you're not likely to dissolve back the whole dielectrics layer on negative side of AC: too short. Furthermore, you heal the layer back on each positive wave.

So, the mechanism of distorsion is as follows:
  1. On negative values of signal under the electrochemical potential, the component acts as a good cap with its specified capacitance.
  2. Above the electrochemical potential, since the dielectric layer is eroding, capacitance goes higher and sustained voltage goes down. This mechanism evolves in time, but soon...
  3. a positive voltage occurs, which can first rebuild the dielectric layer (so a time and voltage-varying current flows through the component), then
  4. the capacitor is rebuilt back to its pristine state.
One should note that during phases (2) and (3), the relationship current/voltage is far from linear.
So, the distortion shown in the article can be easily explained without resorting to dielectric absorbtion or soakage or even quantum dots (oh, not even yet invented at the time!).

So, why do I criticize since I admit these distorsions?
Because they can be easily avoided as long as you know how to design analog electronics.



In this post, I only addressed part I of the first document. I still have to flame part II. Large matter to feed the fire!
Then, I will have to address relevance of critics on the base/collector and gate/drain capacitance vs that of tubes. On Part III or IV, depends on my time.
I will quote Dawson (still not yet decided whether he has an acute sense of humor, or was really serious...): "However don't expect a tutorial unless you're willing to pay for it".
I think I'll be paid if the level of technicity of this forum increases above hunting quacks (furthermore from fossilized ducks)


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