On Thu, 23 Apr 2015 10:46:27 -0700, RobertMacy
wrote:

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.

Most of the 192 KHz cards will digitize to 24 bits. That's a
theoretical 144 dB:
http://en.wikipedia.org/wiki/Audio_bit_depth#Quantization

These daze, the next big thing are 32 bit 384 KHz sound cards:
https://hifiduino.wordpress.com/2011/12/28/musiland-dragon/
http://www.antelopeaudio.com/en/products/Zodiac-Gold-DAC
http://www.speeddragon.com/index.php?controller=Default&action=ProductInfo&Id =572
http://www.amazon.com/dp/B00A2QL1CI/?tag=fox003-20
These are audiophile grade toys, so please have your loan advisor
available before pricing.

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.

Good point. Close enough. However, for a few centi-bucks extra, a
384 KHz sound card will probably work up to about 150 KHz.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558