On Thu, 23 Apr 2015 08:21:00 -0700, Jeff Liebermann
wrote:

On Thu, 23 Apr 2015 05:35:06 -0700, RobertMacy
wrote:

Or, you can use your soundcard and do any spectrum from 10Hz to around
91kHz, and actually get plots of Re(Z) amd Im(Z) vs Freq. I used my card
nad found a 'tracking' relationship between reactive impedance and the
loss in an aluminum cap! My whole career, that was something I never
knew
existed [paid attention to]! But, found verified in an AppNote from AVX.
Very educational to 'play' with such an inexpensive instrument.

ESR is normally measured at 100KHz. A 192KHz sound card won't do
100KHz.

I'm more into the RF chacteristics of passive components which
requires a VNA (vector network analyzer). For example:

"Measuring Capacitor Parameters Using Vector Network Analyzers"
http://electronics.etfbl.net/journal/Vol18No1/xPaper_05.pdf
Notice on the first page that the authors redefine ESR as the residual
resistance at resonance. Sigh.

Oops. gotta run...


a Soundcard that can do 192kS/s, like Creative Lab's old EMU1212, will
give you over 120 dB dynamic range to approx 89kHz. That ratio is 89% of
100kHz and as people have noticed there's not a lot of difference being
slightly off in frequency by small margin. How much 'error' between 100kHz
and 89kHz would one expect when measuring esr? Well, unless here's a high
Q resonance in there.