Caution - InterAv "Spike Guard" Capacitor

In article ,
Jim Weir wrote:
Ah, no sir, sorry. You may want to google how an electrolytic capacitor works.

I got my initial commercial 1st class broadcast engineer license in 1970.
I've got a fair library on the bookshelves.

But thanks the advice.

From Meade, "Foundations of Electronics", from which I've been teaching freshman
engineering students for a few years now...

"The external aluminum can, or housing, is typically the negative plate (or
electrode). The positive electrode external contact is generally aluminum foil
immersed or in contact with an electrolyte of ammonium borate (or equivalent).

...

To create the dielectric, a dc current is passed through the capacitor. This
causes a very thin aluminum oxide film (about 10 microcm thick) to form on the
foil surface. THIS THIN OXIDE FILM IS THE DIELECTRIC."

Emphasis mine. Meade 1. Bonomi 0.


I fully understand the difference between electrolyte and dielectric.

I note that the dielectric was _not_ the subject under discussion.


Meade identifies two plates in the electrolytic capacitor -- the first
being (usually) the can; the second being the foil. I do maintain that the
electrolyte is 'between' those two plates.

Furthermore, I've used electrolytic capacitors that were constructed
with two foil plates, which did *not* use the 'can' as part of the circuit.
You get significantly higher capacitance values that way -- in the same
_physical_ space --by minimizing the 'distance' of the ion transference.

If one _was_ discussing the characteristics of the dielectric, it would be
appropriate to call it "dielectric materialism". groan Which I will
stay away from, other than to note that if the electrolyte is _not_ present
between the plates of the capacitor, then the dielectric does _not_ form
when current is supplied. And all you have is the equivalent of an 'air gap'
type with a surface area approximating that of the 'can', in the case where
the can is used as the negative plate. In the case of a 'dual foil' plate
design, the usual result of loss of electrolyte is an "arc-over", aka short,
between the plates. A "catastrophic" failure of a near-explosive proportions..


Jim


bonomi@c-ns. (Robert Bonomi)
shared these priceless pearls of wisdom:

-
-The electrolyte in a capacitor, just like in a battery, is what is _between_
-the plates.

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com