### Author Topic: Capacitive & Inductive Impedance Plots with SDS2104X Plus Bode Function  (Read 5437 times)

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#### mawyatt

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##### Re: Capacitive & Inductive Impedance Plots with SDS2104X Plus Bode Function
« Reply #25 on: April 22, 2023, 03:37:52 pm »
While developing some Python routines for displaying & plotting various LCR Meter functions we decided to investigate how well the SDS2104X+ Bode Function would hold up to a quality Lab Grade LCR meter such as our Hioki IM3536 when plotting Impedance vs frequency over a frequency range much higher than typical LCR meters support. You can follow the LCR software sweeping & plotting development details in this link.

https://www.eevblog.com/forum/testgear/lcr-meter-plot-software/

Most moderately priced LCR meters don't go beyond 10KHz or 100KHz, the IM3536 supports 8MHz and why we have it, and it was expensive!!

For a quick evaluation of the SDS Bode Function compared to the IM3536 with the new Python plotting routine we selected a typical 1uF Mylar Film capacitor as DUT and a frequency sweep range from 100Hz to 8MHz, well beyond a typical LCR meter range. A Micsig DP10007 was used to differentially sense the voltage across the DUT on the SDS2104X+ Channel 2, and a 50 ohm resistor used as the R current sense for Channel 1. The Bode left axis is scaled by 20Log(R), or ~34dB with the 50 ohm shunt.

From the Bode plot you can see the impedance magnitude at 1KHz is 10.26dB and with scaling becomes 44.24dB ohms, or ~163 ohms which corresponds to 0.977uF at 1KHz, and series resonance shows ~683KHz. Both agree well with the IM3536 LCR plot as shown.

Anyway, the Bode function is not a replacement for a quality LCR meter, nor a VNA, but can be useful in a pinch or just having fun fool'n around.

As usual, YMMV.

Edit: Ran another quick set of plots with a small ~1mH Inductor. Note at 10KHz the Marker shows 4dB, add the 34dB (20Log(50)) and one arrives at 38dB ohms or 79.4 ohms, which is ~1.27mH.

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« Last Edit: April 22, 2023, 08:36:23 pm by mawyatt »
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