Products > Test Equipment

LCR Impedance Viewer for Picoscope+Keysight+R&S Bode Plot Data (open source)

<< < (26/30) > >>

Hans Polak:
One last thing, here is the same file 100R+10nF but now compensated for the measuring probe with a calibration file.
That makes a visible difference, but although Resr is now a bit noisy at LF, it is still considerably above 10Khz.
I have attached both the image and the Excel file.

Hans


_Wim_:

--- Quote from: Hans Polak on May 17, 2021, 08:40:51 pm ---And as said, it's obviously not the math that is wrong...

--- End quote ---

And as said, it's obviously not the math that is wrong  :-DD  :phew:


--- Quote from: Hans Polak on May 17, 2021, 08:40:51 pm ---but there must be something going wrong in your calculation giving L=246H and Resr=50R at 100Hz instead of 21.6H and 43.8K, and there is more.

--- End quote ---

I wonder if it has some has something to do with the gain limit I already told you in post 104?

_Wim_:

--- Quote from: Hans Polak on May 17, 2021, 09:09:58 pm ---You mentioned to limit the gain to one.
That will indeed increase the value of L considerably (and influence the capacity) , but also the value of Resr will increase to ca 47K at 100Hz and higher.

--- End quote ---

I just checked your excel file and did two things:
- copied all the formula's from the first row down until the end (formula's in the first row where correct but they did not go all the way down)
- set all of the positive gains to zero

=> Resr goes to -50 ohms  and stays there.

But, you are using a logarithmic axis in Excel, and that does not plot negative numbers


--- Quote from: Hans Polak on May 17, 2021, 09:09:58 pm ---So after all the things I have done so far, it seems fair to say that now it's your turn to tell what exactly it is that you do on top of calculating the formulas , that may help to explain part of the differences.

--- End quote ---

I only limited the gain to negative numbers as explained immediatly when you reported the problem. With the changes above in Excel you get the same results

_Wim_:

--- Quote from: Hans Polak on May 17, 2021, 09:33:38 pm ---One last thing, here is the same file 100R+10nF but now compensated for the measuring probe with a calibration file.
That makes a visible difference, but although Resr is now a bit noisy at LF, it is still considerably above 10Khz.
I have attached both the image and the Excel file.

Hans

--- End quote ---

To prevent repeating myself:


--- Quote from: _Wim_ on May 16, 2021, 04:40:12 pm ---I am not sure how I need to interpret these result. Is the just probe the result without the 75pF, the the calibrated the result with the 75pF cap & then calibrated? Can you post a plot where you see in one graph:

- DUT measured with no 75pf cap at scope input
- DUT measured with 75pf cap at scope input
- DUT measured with 75pf cap at scope input & with calibration correction implemented

1 & 3 should be identical in an ideal calibration situation, 2 should be different enough to see the calibration "working"

--- End quote ---

Hans Polak:
Wim,

1) What an incriminating suggestion that the formulas in my Excel file were not pulled down and that only the first row was correct.

2) What a totally wrong decision to make all gain figures above 0dB zero, but leave the rest for what it is.
This results is a totally crippled plot giving that silly 50R for Resr in case of the file we were discussing.
There is nothing wrong with values above 0dB, it can be because of an LC resonance or a channel gain issue, but FRA Imp Viewer can never know  what the reason is.
In case of a channel gain difference, one thing the  user could do if it bothers is to subtract the same dB value from all samples, but a much better thing to do is to correct the file with the probe's calibration file.
Conclusion: FRA Imp Viewer is indeed willingly and totally superfluous corrupting files.

3) Keep repeating yourself when it's not obvious what I mean with file compensation with the Probe's calibration file. Everybody else will perfectly understand what this means.

It's obvious from the above that I'm done with you, the way you react is like stung by a bee and turning every discussion into an ordinary fight.

Hans

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod