"Paul Keinanen" wrote in message
...
On Mon, 30 Apr 2007 06:28:17 -0600, Jack Schmidling
wrote:

I keep seeing caps described as "computer grade" but a search for a
definition comes up with zilch.

In the 1960/70's computers were the only application requiring very
low voltage stabilised DC power supplies, +5 V for TTL, +6 V for DTL
and -5.2 V for ECL. Other high power DC applications in those days,
such as industrial automation, used 24 V, but relays weren't sensitive
to ripple or voltage variations.

When a typical computer consumed several kW at 5/6 V, quite huge DC
currents were required and thus the power supply capacitance in linear
power supplies had to be huge.

I have seen this "computer grade" term used in the 1970's when some
surplus companies tried to sell some huge size capacitors, when
physically smaller capacitors became available with the same
capacitance, in order to justify the size of the surplus units.

But after the 1970's I have never seen the term "computer grade" used.

Paul OH3LWR


The term "computer grade" is in use today. See
http://www.mouser.com/catalog/629/576.pdf
and
http://www.mouser.com/catalog/629/574.pdf
for examples of those currently manufactured by Vishay/Sprague and
Mallory/CDE.

I suspect that the term "computer grade" signifies capacitors with screw
terminals. However, I can't prove it.

Cheers,
John