[TCML] Measuring capacitance

[David Speck]

Brandon,

You can calculate the effective capacitance of series/parallel 
arrangements mathematically. 

Capacitors connected in parallel are simply additive.  Caps in series 
combine as the sum of their inverse values, just like resistors 
connected in parallel. 

The voltage rating of a set of parallel caps is only equal to that of 
the lowest rated capacitor.  If you series equally valued caps (same 
voltage and capacitance), the total voltage rating for the string is 
equal to the sum of ratings of the individual caps.  If you series 
unequal valued caps, then the voltage rating calculation gets rather 
complex (something to be avoided). 

Before you start building high voltage equipment, you would do well to 
get some basic theory under your belt.

Many high end digital meters include a capacitance measuring function.  
You can also buy specific cap meters for not a lot.  However, these are 
mostly useful for testing that a cap is actually exhibiting its stated 
value.  Note, however, that in high voltage use, a cap may seem to have 
proper values when tested with a meter, but fail when subjected to high 
voltage. 

Dave

Brandon Hendershot wrote:
> I'm looking to make a new tank cap this Christmas and I'd like some 
> help from a meter to measure the farad rating to aid wiring the in a 
> mixture of series and parallel. The only thing I can think of that 
> would measure farads is an ohmmeter. Do they make a farad meter? If 
> not, how do you convert ohms to farads?