----- Original Message -----
From: "Keith Dutson" <firstname.lastname@example.org>
Sent: Tuesday, December 28, 2004 12:37 PM
Subject: [TowerTalk] Simple Capacitance Question
> How does one increase the current rating of a capacitance circuit?
> I have a mica capacitor rated at 540pf/500v. If two are wired in parallel
> the result is 1080pf/500v.
And the combination is double the current rating (assuming the C's are
really the same.. Mica caps are probably 20% devices, so, in the worst case,
the current won't divide 50:50 but, rather, 60:40, so the parallel
combination would be rated at 166% of the rating of a single cap)
If two of these pair are wired in series the
> result is 540pf/1000v. Right or wrong? Is the current rating double?
Series combination has current rating of a single cap, and voltages divide
in inverse proportion to C (smaller cap gets bigger voltage), so, depending
on tolerances, you need to figure for the smaller value.
Two paralleled series strings would give you the doubled current rating, as
> Another configuration that comes to mind is two 540pf/500v wired in series
> to give 290pf/1000v. Wire two of these in parallel to give 540pf/1000v.
> Will this double the current rating?
In all these series/parallel combination things you need to take a step back
and look at tolerances, and, depending on the application, what happens if
one device happens to fail open (i.e. the solder joint comes loose).
The difference is in whether the two midpoints of the series strings are
connected (does it look like an H?)...
> Keith NM5G
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> TowerTalk mailing list
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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