[TechAssist] Re: Capacitors
- From: "J Silverman" <greentron@xxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Fri, 8 Nov 2002 15:02:28 -0500
The leakage is nonelinear so the capacitance becomes frequency and amplitude
dependent. When I used to work as an applications engineer for a capacitor
manufacturer we had a small contract to supply large value none-polars for
an application involving very low frequency aircraft control servo circuit
components. They were willing to put up with the wierd behavior but we did
have to define it in the form of a specification. Could not get adequate
performance with wet aluminum because the capacitors properties kept
changing and ended up using solid tantalum. Even so, had to derate to 10% of
rated voltage.
Jerry Silverman
Greentron Inc
4 Newland Ave
Greenville SC 29609
864 232 3889
Fax 271 2080
mailto:greentron@xxxxxxx
----- Original Message -----
From: "Joe Batchelor" <jbc@xxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, November 07, 2002 11:36 PM
Subject: [TechAssist] Re: Capacitors
>
> I think it is very important to be able to substitute a part
> on hand for one that must be ordered. It is not practical to
> stock every cap that is needed.
> It is also important to understand what is going on so that
> a wrong substitute is not used.
>
> Each cap voltage must be greater than the operating voltage.
> The value of the cap is the same as the replacement. The value
> does not divide as in series caps.
>
> When one cap is reversed biased the leakage is very great and the
> full supply is across the other cap.
>
> Joe Batchelor CET TX 80
>
> 11/7/02 10:14:30 PM, "al m" <ampm@xxxxxxx> wrote:
> >
> >The only way to solve this is to use the right cap. Don't start another
> >bullshit topic where everybody has his own advise,
> >al marquardt
> >ampm@xxxxxxx
> >
> >
> >----- Original Message -----
> >From: "Al Gutz" <alg@xxxxxxxxxxx>
> >To: <techassist@xxxxxxxxxxxxx>
> >Sent: Thursday, November 07, 2002 11:05 PM
> >Subject: [TechAssist] Re: Capacitors
> >
> >
> >>
> >> The voltage accually of each cap should equal the required voltage. The
> >> DC resistace of an electro is very low. You will see numerous arguments
> >> about this, to satisfy yourself just dissasemble a commercially made NP
> >> cap.
> >>
> >> Al G
> >>
> >> Gary McCartney wrote:
> >> >
> >> > You can join two polarized caps together in series, either positive
to
> >> > positive or negative to negative. The cap must be twice the value in
uF
> >> > as the original cap and can be half the voltage rating or higher as
the
> >> > the original.
> >> >
> >> > Please note that there has been some very technical reports written
up
> >> > on these email lists, where a knowledgable technician has described
that
> >> > installing two caps back to back in series can eventually cause harm
to
> >> > the capacitors. There are also ideas where diodes are placed across
each
> >> > cap to prevent reverse charges but I can't recall how these would be
> >> > wired in. I probably still have that write-up somewhere on my hard
> >> > drive. If anyone seriously wants to read it, I will hunt for it.
> >> >
> >> > Mouton's Electronics wrote:
> >> > >
> >> > > Hi all,
> >> > >
> >> > > My father who has been in the buisness for over 30yrs had an
> >interesting idea. I have a tv that will require a NP capacitor and Dad
seems
> >to remember that it was possible to make a NP out of 2 polorized
capacitors.
> >He, however, doesn't remember how to do it. My question is, is it
possible
> >to do and how? I hardly remeber this being a possibility from school and
> >like most shops don't stock a variety of NP capacitors.
> >> >
> >> > ******* ATTENTION, PLEASE ********
> >> >
> >> > I have a new email address. Please
> >> > send all email in the future to:
> >> >
> >> > "Gary McCartney" <gary@xxxxxxxxxxx>
> >> >
> >> > Thanks.
> >> >
> >> > Gary McCartney
> >> >
> >> > McCartney Electronics
> >> > 7134 Fife Rd, RR 7
> >> > Guelph Ontario Canada N1H 6J4
> >> > Fax: (519)821-1530
> >> >
> >> > >
> >> > > thanks in advance
> >> > >
> >> > > Jason Mouton
> >> > > Mouton's Electronics
> >> > > 1116 Center St.
> >> > > New Iberia, LA 70560
> >> > > 337-364-1641 Phone/Fax
> >> > > moutons@xxxxxxxxxxxxxxxx
> >> > >
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> >> > --
> >> > ******* ATTENTION, PLEASE ********
> >> >
> >> > I have a new email address. Please
> >> > send all email in the future to:
> >> >
> >> > "Gary McCartney" <gary@xxxxxxxxxxx>
> >> >
> >> > Thanks.
> >> >
> >> > Gary McCartney
> >> >
> >> > McCartney Electronics
> >> > 7134 Fife Rd, RR 7
> >> > Guelph Ontario Canada N1H 6J4
> >> > Fax: (519)821-1530
> >> >
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