Jack Schmidling ) writes:
I keep seeing caps described as "computer grade" but a search for a
definition comes up with zilch.

What does this mean? As the vast majority of computers are owned by the
masses, one could assume it means sleazy consumer quality. Or it could
mean the kind of computer that prevents ICBM's from being accidentally
launched.

The term was around in the early seventies, at least. That was when
solid state was still relatively new, and electrolytics were not
as advanced as nowadays. I built 1A power supply in the fall of 1972,
and had found at a hamfest a "computer grade" electrolytic, in a
metal can,10,000uF at about 20 volts. It was about the size of a Coke can.
It was pretty massive in terms of capacitance at the time, the regular
electrolyitics were hard to find in such large values, and even this
one was barely sufficient in terms of voltage rating.

It was obviously surplus, from mainframe computers. I have no clue
whether they were particularly better than the regular electrolyitics,
but they were obviously the source for larger value filter caps at
the time. I'm sure some of it was merely hype, at the very least
"computer grade" says where the capacitors came from.

It's obviously different now. I can easily get 10,000uF electrolytics
in a far smaller package and with a bigger voltage rating. I haven't
evne noticed the term in a long time, other than the occasional question
about the term (it has come up before here or in one of the
sci.electronics.* newsgroups.

There obviously are different grades of electrolytics, with things
like temperature rating being important in some applications, and ESR
being important in others (especially things like switching supplies
where they have to deal with higher frequency waveforms). But
the talk is in terms of their specs, rather than some mythical
"computer grade" capacitor.

Michael VE2BVW