"Michael" <NoSpan@att.net> wrote in message
news:42874D32.71868CB0@att.net...
Quote:
"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:
I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:
OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115
Judging from the last line, they're 14 years old. They've never
been
used, AKA New Old Stock. Every resistor measures greater than 5%,
some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older
than
these and they still measure within 5% tolerance, usually within 2%.
Thanks.
Do you know their history? Maybe they were out of tolerence at time
of
manufacture.
|
I don't know their history, only that they are still in the tape that
they were in when they came from the factory, with the factory
designation stamped on the tape, so they should be NOS. I've seen tapes
from some place that have various components customized for a stuffing
machine, and this is not one of those.
One would think that it would not be possible for these to be out of tol
when they come from the mfgr, unless there was a major malfunction in
their testing equipment. However, I've heard of such things as
warehouses catching on fire, or goods being shipped in a ship hold next
to a steam boiler, where in either case the goods were exposed to
excessive temperatures. This could have caused some change. But my
experience is that higher temperaturss cause resistors to become lower
resistance.
Quote:
I always heard that carbons change value with humidity. I have many
unused
Allen Bradley 5% 1/2W carbons which I took from new stock in the early
70's, and
checking a few of the BROWN-third-band ones at random show all within
tolerence.
|
I checked another bag of loose carbon comp resistors, 6.8 ohm, 1/4W, 5%.
All of them are also greater than 5% out of tolerance, and that is
taking into account the 0.4 ohm resistance of the test leads.