Non-polarized fixed capacitor
A non-polarized ("non polar") capacitor is a type of capacitor that has no
implicit polarity -- it can be connected either way in a circuit. Ceramic,
mica and some electrolytic capacitors are non-polarized. You'll also
sometimes hear people call them "bipolar" capacitors.
Polarized fixed capacitor
A polarized ("polar") capacitor is a type of capacitor that have implicit
polarity -- it can only be connected one way in a circuit. The positive lead
is shown on the schematic (and often on the capacitor) with a little "+"
symbol. The negative lead is generally not shown on the schematic, but may
be marked on the capacitor with a bar or "-" symbol. Polarized capacitors
are generally electrolytics.
Note that you really need to pay attention to correctly hooking a
polarized capacitor up (both with respect to polarity, as well as not
pushing a capacitor past its rated voltage). If you "push" a polarized
capacitor hard enough, it is possible to begin "electrolyzing" the moist
electrolyte. Modern electrolytic capacitors usually have a pressure relief
vent to prevent catastrophic failure of the aluminum can (but don't bet your
eyesight on this).
----- Original Message -----
From: "Chris BONDE" <ve7hcb@rac.ca>
To: "W0UN--John Brosnahan" <shr@ricc.net>
Cc: <towertalk@contesting.com>
Sent: Monday, August 05, 2002 4:02 PM
Subject: Re: [Towertalk] Tailtwister won't turn.
> I have never understood the polarization of an electrolytic
> capacitor. Does that mean they ack like diodes as well?
>
> Chris opr VE7HCB
>
> At 05:36 PM 2002-08-05 -0500, W0UN--John Brosnahan wrote:
>
> >At 03:13 PM 8/5/2002 -0700, Mark wrote:
> >
> >
> >>Why? Does not matter, but the practice is fine! I do things by habit,
> >>too.... It is AC .. does NOT matter.. pluskies or minusers...just back
to
> >>back.. did it for years in speaker crossovers as well as motor starting
> >>capacitors .. as we are discussing and reading about here. Mark 6dx
> >
> >We are talking POLARIZED electrolytic caps here--it DOES matter.
> >You can get away with it (sorta) with audio because the voltages
> >typically are not that great--but they really need to be back to back
> >and ideally with diodes across them to eliminate the reverse voltage
> >in motor-starting applications.
> >
> >The real question is whether you need to divide the effective capacitance
> >by two. The caps are really NOT in series in the classical sense--but
rather
> >one cap handles the half cycle voltage of one polarity with the
capacitance
> >with which it is marked. Then the other cap handles the other polarity
> >half-cycle with its capacitance. So it seems to me that maybe the
> >effective value does not need to be halved.
> >
> >--John W0UN
> >
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>
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http://www.mscomputer.com
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