[mdlug] [Fwd: Re: bios battery]

[Jeff Hanson]

On 1/16/07, Raymond McLaughlin <driveray at ameritech.net> wrote:

> Also, one question for anyone who might know: The caps I'm looking at
> are marked 1500 mfd, 6.3V, 105 deg C. How much lee way do I have on any
> of these?
>
> OK, the temp is obviously a maximum not a minimum, I just included it
> for completeness.
>
> I'm pretty sure the voltage is more of a maximum rating than a rigid
> spec, so a little higher should be OK, I think.
>
> What about the capacitance? My understanding is that these capacitors
> serve as "power smoothers" i.e. by holding a charge, at an applied
> voltage (not likely to be exactly 6.3V), on a DC power circuit, they
> compensate for microsecond dips in the supplied voltage as power usage
> fluctuates among the components. If this is the case then you should be
> able to get away with a little over capacitance, but not under.
>
> No doubt an exact match if probably best, and these are probably not
> that hard to find if you really look, so I'm just wondering.

Actually it is a little more complicated.  In switching power supplies
the Equivalent Series Resistance is critical.  If you give me all the
numbers and letters on it, the diameter, length, and in spacing in mm,
and a picture of the manufacturer's logo I may be able to find an
exact match.