Re: Equalizing resistors for electrolytic capacitors

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Eric,

Im not quite sure what you are trying to achieve with the resistors but
maybe this will give you an idea.

for example, if you have three caps in series of unequal values C1 C2 and
C3, the voltage for say C1 (due to capacitive voltage division would be:

                        (1/C1)
V1 = ---------------------------------- * Vsource
         (1/C1) + (1/C2) + (1/C3)

so if you are trying to find the resister ratio that maintains the natural
capacitive voltage division you would set:

                        R1                                           (1/C1)
         -----------------------------------
=  ---------------------------------
               R1 + R2 + R3                   (1/C1) + (1/C2) + (1/C3)

(I hope this doesnt get mangled too much - dont know how to set the fonts on
a reply)

There will be infinite number of solutions so you need to choose a value for
say R1  that gives you the time constant you want then R2 and R3 will be
determined

If you are trying to get equal division with unequal C's then R1=R2=R3 and
the time constant need to be small enough to maintain equal division.
(maybe better to match your electrolytics for equal division

Gerry R


> Original poster: "Hydrogen18" <hydrogen18@xxxxxxxxxxxxx>
>
>      I have a large number of small electrolytic capacitors I am trying to
> connect in series. Since they have the nominal -10% to +85% value control
> on them the potential exists for a unequal division of voltages. I
> understand than resistors across each capacitor can help solve this
> problem, but have found no formulas or examples on what values should be
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> used. Is it an arbitrary thing? Any help you could provide would be
greatly
> appreciated.
>