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On 04 Feb 2017 23:46:23 GMT, Jim Mueller wrote:

On Sat, 04 Feb 2017 15:26:31 -0600, oldschool wrote:

On 03 Feb 2017 02:13:07 GMT, Jim Mueller wrote:

The old electrolytic capacitors you are talking about don't sound like
the oil filled variety. Indeed, if they are electrolytic, they aren't
oil filled. Oil filled capacitors aren't polarized and many of them are
good today. They were the high quality capacitors used in military and


I always thought those were oil filled, but I see I was wrong. I looked
on the web too, and it appears that most of them were filled with a
boric acid solution, which is not really harmful. They all had the tiny
vent hole in the top, and had a large threaded mounting on the bottom,
which required a sizable nut.

It's been years since I touched one of them. I only remember (vividly)
getting sprayed by one of them many years ago. It was boiling hot and it
hurt like hell. After that incident, I just replaced them before I even
pluggd in anyting that had that type of cap. (Or put a soup can over
them temporarily) They were probably the worst caps ever made.

Here is a pic I found online.
https://antiqueradio.org/art/Midwest18-3621.jpg

Progress is incremental. Those capacitors had major advantages over what
came before. The "dry" electrolytics that followed them had further
advantages. That's how things go.

I know the dry 'lytics were better, I have to ask what came before these
wet ones with the vent hole? I really dont know...

When I was a kid, I liked taking old radios to bits. A mains reservoir
electrolytic I "autopsied" had a centre electrode that was sort of like a
curvy column (for maximum surface area) up the middle, the can was the other
electrode, it was completely filled with electrolyte. Another old radio had
a compartment under the one that housed the chassis, it contained a huge
slab flat wound paper capacitor - it must've weighed at least 7lb.