[Elecraft] Carbon Composition Resistors - Aging

[Ron D'Eau Claire]

I have some carbon composition resistors that I acquired a while back (half
a century ago when they were new).

Some look shiny as if covered in a varnish. I find those to tend to be
fairly close to their original values. Certainly they are within their
original specification (typically 10% signified by a silver band after the
multiplier). 

Others have a dull finish. Those tend to be higher than their original value
- sometimes by a huge amount. Perhaps four or five times their original
value. 

I recommend checking the values. If they are still "in spec" after all this
time, they will probably stay in spec if you don't abuse them. 

Back then we paid a huge penalty if we wanted a resistor within 5% or
(gasp!) 1% of the stated value. They were used only in a very few critical
places. Nowadays we routinely expect 1% tolerance from ordinary
off-the-shelf cheap resistors. 

Most circuits still don't need that accuracy. It just happens that with
modern computer-controlled manufacturing processes it's as cheap to make a
1% resistor as it is a 10% resistor. 

Ron AC7AC