[Milsurplus] CarbonFilm / Metal Film Resistors

[antqradio at juno.com]

This question seems to come up from time to time.  There is a reason it
is hard to find carbon composition resistors.

Film resistors are plainly superior to composition resistors just as film
capacitors are superior to paper capacitors.  The lead inductance,
assuming a leaded component, is the major source of parasitic inductance,
in either composition or film resistors.  Film resistors contribute less
thermally induced noise to the circuit, have higher power ratings then
composition resistors (for a given physical size) and are much less prone
to a change in value with temperature.

The fine tuning of a film resistor value might be made by cutting a
spiral into the film of a leaded resistor.  In film chip resistors, the
value is fine tuned by cutting an "L" into the film.  In any event, the
"turns" are few and the resulting inductance is very very small.

Regards,
Jim


On Sun, 13 Mar 2005 23:05:46 -0500 <jimandterri at bellsouth.net> writes:
> When replacing carbon composition resistors, at  what frequencies do 
> I need to be concerned about the inductive effects of the newer 
> carbon film and metal film resistors, I assume the metal film would 
> be far more of an issue  I have seen some vague suggestions but not 
> much specific info. Has anyone seen any real world problems in this 
> area?
> JMS.
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