Electronics > Beginners
Measure the equivalent resistance in a simulator
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bonzer:
 :( Then what do I get? And why?
iMo:
You have to provide an "AC analysis" with the 1A "AC" current source as the Signal Generator.
That is a special SPICE directive:  .AC type np fstart fstop ..

When 1A AC current source is used the AC analysis returns complex "impedance" (R+iX) as the function of frequency. The "R" is your "resistance".

The impedance is returned as seen from the AC current source (PS: also a Voltage source is used with the analysis, but not here).

And you may plot that function in several formats, ie Bode, etc.

Here is something to read:
https://class.ece.uw.edu/cadta/hspice/chapter_9.pdf


--- Quote from: imo on January 11, 2019, 09:01:48 am ---In LTSpice: Use 1A AC current source, do AC analysis and set plot to Bode, set the dB axis to Linear.
Attach the 1A current source into the points where you want to measure.

--- End quote ---

bonzer:
I think I did the same in PSPICE. It worked well for the other cases (for C1,C2,C3,C4 corrspend to the right values).  Only now it gives a different value. I'm gonna try it on LTSpice later, I can't do it now.
Zero999:
SPICE assumes capacitors are in Farads and m is the standard SI prefix for 0.001. C2 to C4 are massive. 100mF is 0.1F or 100 000µF.

Are you sure you don't mean 100µF?
iMo:
Then you need to plot the AC analysis results properly.
The AC analysis plot in LTspice is done automatically (you do not need to assign the Nodes, as the 2 nodes are given by the nodes where AC source is wired in).

From what I see above you do plot some voltage diffs - that is not good here.

The "Vs2" in your schematics should plot the Resistance.

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