[Gllug] Power Supply loaner in West London?

[Chris Bell]

On Thu 23 Sep, Russell Howe wrote:
> 
___a good description of electrolytic capacitors. They work by having two
conductor plates coated with chemicals and held as close as possible to each
other with as great a surface area as possible. The chemical action modified
by the applied voltage produces a very thin insulating layer, only just
thick enough to be capable of withstanding the voltage, while the surface
area is increased by the etching action on the metal plates. The plates are
coiled together with a paper separator so that both sides of the conductors
are active, and connected so as to reduce the induced magnetic effect of
current moving through a coiled conductor.
   The designed current handling depends on the thickness of the metal
plates and the quality of the connections, but the capacitor fails as it
dries out. The better quality long-life capacitors require more space for
heavy duty plates, thicker separators, and extra electrolyte. Gas is emitted
by the capacitor, so there must be a safety vent, although it allows the
capacitor to dry out, or the can is deliberately weakened to limit damage as
it fails.
   It still depends on slow chemical action, there is always a small leakage
current through the insulating layer, increasing rapidly as the voltage
increases above normal, while the capacitance reduces as the insulating
layer thickens, all tending to give broad specification tolerances and poor
high frequency high power performance.

-- 
Chris Bell

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