Measuring feline capacitance
"Touch Not The Cat, Bot a Glove" 





DTTAH / ACNR / IANAL / YMMV *

Equipment:
High impedance voltmeter / oscilloscope with HV probe.
High voltage low capacitance capacitors (1 10 100 1000 pF) x 2 of each. 

Pretest - charge capacitors to some semi known high voltage and measure with voltmeter to determine measurement ability. 

For purrfect results there should be minimal paws between first and second iterations of 2.3.4. 


Select cap - say 100 pF.  
Discharge cap (short)   
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.)
.... (Cap and cat are now at same purrtential)
Disconnect cap from cat   
Measure Vcap
repeat 2. 3. 4. 
Compare readings.  
Repeat with higher and lower caps. Aim is range where V1 / V2 is usefully high - say about 2:1.


Processing.

When cap connects to cat cap is charged. Cat and cap share charge in proportion to capacitances. Overall voltage drops to reflect increase in system capacitance from addin cap to Ccat. If Vcat before and after transfer was known you could calculate Ccat.
But Vcat 'a bit hard' to determine.
Repeating process gives a second point and 2 simultaneous equations can be solved to give Ccat.  

If Ccap &lt;&lt; Ccat the delta V is small and results are ill conditioned.
If Ccap >> Ccat the delta V is large and results are ill conditioned.

If Ccap ~~~= Ccat the porridge is just right and the bed is just right.
If Ccap = Ccat then voltage will halve on second reading.
V = Vcat_original / 2  

Otherwise ratio change is related to inverse proportion to capacitances.
V2 = V1 x Ccat/(Ccat + Ccap) or

Say V1/V2 = 0.75 
Ccat = 3 x Ccap.

E&amp;OE ....



DTTAH ......  Don't try this at home
ACNR ........ All care, no responsibility
IANAL ....... I am not a lawyer
YMMV  ....... Your mileage WILL vary
E&amp;OE  ........ Errors &amp; Omissions excepted.