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March 1998

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Subject:
From:
SteveZeva <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Sat, 7 Mar 1998 22:41:48 EST
Content-Type:
text/plain
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text/plain (40 lines)
Darcy,

    You pretty much got the basics...3 digits usually are +/- 5% tolerance,
and 4 digits are +/- 1% or better. Most resistor manufacturers try and stay to
the same standard, but there are still a bunch that have their own way of
marking. To be sure of the value, a good ol' ohm meter can't be beat.

     The colors may indicate a tolerance in some cases, in others they don't.
You might run across resistors that will have a letter in the middle of the
digits. For example using 10K ohms as the value, you may see something like
this: 10R3
the ten is the significant figure, the R the tolerance, and the 3 is the
number of zeros. Depending on who made it, the R could stand for 5%, or 1%, or
whatever the resistor manufacturer wants...it makes you wanna scream don't it?

     At one time in the past, I almost had the rework people wanting to lynch
me because I had them rework a bunch of resistors that I thought was the wrong
tolerance. They only had three digits and USUALLY they're 5%, the BOM called
for a 1% resistor. Come to find out that these were really 1%'ers...the vendor
who sold them took regular 5% resistors and measured each one screening out
the less precise ones before they taped them up, needless to say, I bought a
few ladies lunch that day!!  (GRIN)

                                                 I was a bunch O' help, wasn't
I?

                                                       -Steve Gregory-

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