Re: Equalizing resistors for electrolytic capacitors

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "S&JY" <youngsters@xxxxxxxxxxxxxxx>

Eric,

The other factor to consider is power dissapation by the resistors.  Each
resistor will dissapate V*V/R watts.  You may need to string a few of them
in series to keep the power within the rating of the resistors.  Also,
remember that common (cheap) carbon composition resistors are only rated for
about 250 volts across them--another good reason to have at least two in
series.
--Steve Y.

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, November 28, 2004 4:09 PM
Subject: Equalizing resistors for electrolytic capacitors


> Original poster: "Hydrogen18" <hydrogen18@xxxxxxxxxxxxx>
>
> List,
>
>      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.
>
> So far I have come up with:
>
>   I understand the time constant of Tau(R*C) correctly it would be:
>
> 47000 * (330*(10^-6) = 15.51 seconds.
>
> so in about a 78(5 Time constants = 98% charge gone) seconds provided my
> caps are at full voltage they will only be at 2 volts each with a 47k
> resistor across each one.This is still a high voltage when you factor them
> being in series. Although at that low of voltage I should be able to short
> them and they wont have energy to internally damage themselves I think.
> This is for a DC tesla coil filter cap
> ---Eric
>
>
>
>
>