Quote:
Originally Posted by N2IXK
Pretty much ALL electrolytics since the 1930s or so are "dry" types.
The term was originally used to differentiate the then-new paper and aluminum foil types from the older "wet" electrolytic caps which used a liquid (borax?) solution as an electrolyte, and were similar in construction to a wet cell battery. Wet electrolytics went out of favor as soon as the dry types were introduced.
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Interesting. I thought
all electrolytic caps, even present-day ones, were the wet kind. How can today's electrolytics work without
some moisture in them? I bring this up because modern electrolytic capacitors do dry out, just as the older ones did, causing them to change value. Dried-out electrolytics, as we know (or should know), are a major cause of 60-Hz AC hum in radios and televisions (to say nothing of the thimble-size electrolytics in today's flat screens that can bulge at the top--they can cause this type of trouble and worse), and when these caps short, they can destroy the power transformer in the set if the power supply is not properly fused.