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[Omnibus]

@gyulasun,

Thanks a lot for the links. I think in this case it's not exactly impedance matching that's needed but accuracy of voltage measurement. So, it seems to me there should be some experimental ways to determine that in this concrete case. I've posted data from one experiment I thought might indicate what the accuracy is -- when measuring the resistance of a known resistor through dividing the voltage across the resistor measured by the probe by the current passing through that resistor it appears that the 1X probe recovers throughout the entire one period the known resistance better than the 10X probe. Of course, the probes in this experiment are measuring resistance across R rather than across RC which may cause an objection. Can you think of any other way to check experimentally said accuracy?

[Omnibus]

The gist of what @gyulasun's links give as a difference between 1X and 10X probes, as far as I understand it, is that a 1X probe imposes a 110pF (in my case) capacitance in parallel to the scope input. Thus,  this capacitance acts as a shunt and the scope reads lower voltage than the real voltage supplied by the pulse generator. That lower voltage seems to me, however, to be the real voltage applied to the RC circuit, as long as the scope reads it right. Anyway, I did again experiment using the 10X probe but shunting the input by a 115pF capacitor to model the purported behavior of the 1X probe. In this way, having the 10X probe now behave as a 1X probe I was expecting that the OU effect will show up. However, it didn't. The OU effect didn't show up even when I placed a 1MOhm resistor or 100Ohm resistor in series with the 110pF capacitor. OU effect didn't show up also when I replaced the 110pF capacitor with a 21pF capacitor. Obviously, the suggestion that the 1X probe is exhibiting the results because of shunting the inout doesn't hold water.

The only model when the 10X probe gave a result as if it were a 1X probe was when I placed 21pF capacitor and 1MOhm resistor or even just 1MOhm resistor in series with the probe as I showed it in the schematic couple postings back. You're welcome to suggest other critical experiments that would bring clarity and definitive understanding of this matter. Also, feel free to bring other concerns you may think may explain away the apparent OU observed in these studies.

[gyulasun]

...    I think in this case it's not exactly impedance matching that's needed but accuracy of voltage measurement.
...

I agree. However, you would need a less than 1% AC voltage measurement possibility I think.  Fluke makes a 8.5 digit Reference Multimeter, 8508A, that has a +/-65 PPM  (parts per million) of reading accuracy for up to 1MHz AC sinusoid input voltage. (Its price is to be inquired at Fluke, I guess it is in the several thousand US$.)
There is another Fluke Precision multimeter, 6.5 digit, about US$1000,  8845A/8846A types.  They have a .6% AC accuracy up to 100kHz and about 4% at 300kHz. They say a 30% at 1MHz, out of question.

... a 1X probe imposes a 110pF (in my case) capacitance in parallel to the scope input. Thus,  this capacitance acts as a shunt and the scope reads lower voltage than the real voltage supplied by the pulse generator.

The scope reads what the shunt (110pF) capacitance let it read due to its shunting effect, to be more precise. If you were to shunt the FG output directly with a 110pF cap, you would measure the reduced output voltage already.

Anyway, I did again experiment using the 10X probe but shunting the input by a 115pF capacitor to model the purported behavior of the 1X probe. In this way, having the 10X probe now behave as a 1X probe I was expecting that the OU effect will show up. However, it didn't. 

You mean on "shunting the input" actually shunting the FG output with a 110pF directly, correct?  If so, then it is not a model of the 1:1 probe because the 10:1 probe has the series 9 MOhm resistance inside and only then comes the scope 1 MOhm input resistance.  If you did not mean that, then sorry.

rgds,  Gyula

[Omnibus]

@gyulasun,

Thanks a lot for the links and the useful comments. I'll work on them in a bit because now I'd like to discuss a theoretical question first. I keep forgetting the link to to the place I can download a larger file, however. I'd like to upload an Excel file for a theoretical discussion. Can you remind me what that upload link was? Thanks.

[gyulasun]

Omnibus,

If you mean upload link to this Forum, here it is:

http://www.overunity.com/index.php?action=downloads and scroll down a little to the Category Name (in the middle Column).  Good for as big as 5 MB file size, otherwise you may use Megaupload or Rapidshare.