

Measuring Feline Capacitance - mmastrac
http://electronics.stackexchange.com/questions/152090/measuring-feline-capacitance

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ChuckMcM
I am not a cat fan, or a squirrel fan. I do know from observing squirrels
crossing power lines that their dielectric constant is significantly lower
than that of air, but I've never figured out how to determine it strictly from
observation without actually doing an empirical measurement.

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monkeymagic
Squirrels act as inductors in DC circuits. Only once though. There's a high
current surge that drops to zero as they turn rapidly into a carbon resistor!

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kabdib
We had a number of network outages at Apple due to squirrels inserting
themselves in the NOC's power lines.

Note to self: Don't design any circuits that incorporate these animals.
Squirrels make terrible fuses.

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monkeymagic
So true.

We had a different problem. They chewed through the fibre cables between our
offices to get the fiberglass sheath for their nests. Eventually they ran
Ethernet underground because they'd have broken it again in a couple of weeks.

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kabdib
Whereupon: Moles :-)

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stolio
Or, say a cat's roughly a sphere of radius 10cm, capacitance of an isolated
sphere is C=4(pi)(epsilon_0)(radius) = radius/k_e = .1/(9x10^9) = 11 pF

Ballpark. YCCMV.

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grinich
That's the 2nd comment in the highest-voted answer...

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stolio
huh. I ctrl-f'd for "sphere" and missed it.

There goes the high point of my saturday night. Maybe later they'll ask how
many cats running in circles you need to levitate a dog wearing a ferrous
vest.

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anotherevan
This reminds me of a throw-away comment a lecturer made once while discussing
the maintenance of telecommunications equipment. He dryly observed that,
“Burning technicians don’t smell very nice.”

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pvaldes
I'm feeling the desire to build a cat scratcher with multimeter right now...
maybe with some nice bulb leds aligned forming the meow! word.

muahahah... is alive!!!

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walshemj
I imagine getting the kitty to hold still while you attach the clips from your
ESR meter might be the tricky part

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omegaham
I laughed at one of the answers mentioning this:

"Connect one end of cap to ground - one end of cap to cat. .... ( How 'to cat'
is achieved is left as an exercise for the reader.)"

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amelius
Next question: how much energy can it store, until the capacitance breaks
down?

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gweinberg
I don;t think there's a well-defined answer. The "capacitance of a cat" is
actually the capacitance of the cat and some other condictor. For purposes of
calculating the cat's capacitance you can treat the other plate as a grounded
sphere at infinity. It doesn't really matter., you'd get pretty much the same
answer with a grounded sphere a few feet away. But for figuring out how much
energy you can store before you get an arc, it's all about how far away the
second conductor is.

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tonteldoos
I imagine this experiment may not have a high level of repeatability.

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kjs3
Do we have to assume a spherical cat?

