Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "sbdwag" <sbdwag@...> wrote:
>
> What magnitude of inductance,uh,mh would a 2200uf cap have.

It is a value that manufacturers are reluctant to put on their data
sheets.  But integer microhenries is a fair guess for a 2200uF, 35
volt electrolytic.  You have to measure the self resonant frequency of
the capacitor to find out.  2*Pi*F=1/sqrt(L*C) 

The inductance of copper PCB traces in on the order of .3 to .6
microhenrys per foot.  

So struggling to eliminate an inch of trace (.05 uHy of trace
inductance) between an electrolytic capacitor and another component is
pointless.  But since the internal inductance of a ceramic or well
designed film capacitor is in the nano henries, an inch of trace can
make a difference for them.