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

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Hans Polak:
I did measure an actual capacitor.
As mentioned, Serie resistor R=100R, and Dut composed of 100R//10nF.
The .csv file generated with these 3 components was processed by FRA Imp Viewer and separately calculated by Excel as : C=[Im[(1-V)/V)]/(W*R), were V is the complex voltage derived from the .CSV file and W=2*Pi*Freq.
When V=A+jB, where A=Gain*Cos(phase) and B=Gain*Sin(phase), then C=[B/(A^2+B^2)]/(W*R)

Hans

_Wim_:
Hmmm, that does seem indeed strange in that case. I will run a few tests comparing the result of FRA Imp with the analog discovery I have been using instead since I bought one.

_Wim_:
it seems to be a conflict between x64 and x86 build. When I run from visual studio in x86 build mode I do not get this issue.

Attached is an x86 build (which also runs fine on my x64 machine) that does not seem to have the issue (same source code!  :rant:)


=> that does not solve it completely, but when measuring a capacitor only (without parallel resistor) the x64 version was not ok also. But with the parallel resistor results still seem off.

_Wim_:
Found it. The issue is that my calculations are for series capacitance and resistance, and your calculations are for parallel capacitance and resistance.

Ideally, both modes should be supported (this is typically done on LCR meters)

_Wim_:
I have done now a run with the 100 ohm and 22nf (did not have a 10nF) is series, and the FRA IMP gives the correct results.

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