[Milsurplus] Carbon Comp Resistors: The Darkness Gathers?

[Peter Gottlieb]

Is there a smartphone app for resistors where it tells you the value based on 
its camera?


On 7/2/2018 6:25 PM, Mark K3MSB wrote:
> I've found it's the lower values, typically up to maybe half a meg, that go 
> high with the lower values, say under 100 ohms, to be particularly prone to 
> going out of tolerance.
>
> I've about two medium postal boxes of unused carbon comp resistors in the 
> "pile".    Since I'm pretty color-blind the only way I can determine the 
> resistance value is to use a meter, and then I'd have little chance of knowing 
> if it matched the funny colored rings around the body.
>
> 73 Mark K3MSB
>
> On Mon, Jul 2, 2018 at 4:15 PM, David Stinson <arc5 at ix.netcom.com 
> <mailto:arc5 at ix.netcom.com>> wrote:
>
>     I've always heard that the carbon comp resistors
>     that fail Hi-Z most often are those in the
>     Mega-Ohm range ("green band").  Oddly, over the
>     last four major projects:  TCS, ATD, RAX and now
>     SCR-522, haven't found that to be the case.  The
>     resistors most often failed-High are in the
>     15K-500K range, with the #1 "bad guy" being 47K
>     Ohms, followed by 470K.  I remember changing one
>     or two Mega-Ohm value resistor in the last three
>     projects.  Every 47K resistor in the last TCS
>     receiver and in the ATD had to go.
>
>     Which brings me to this:
>     I've got piles of NOS Carbon Comps that have been
>     following me around for eons.  The majority of
>     these have started reading Hi-Z by 5% or more.
>     Many by much more.  I just threw a half dozen NOS
>     100K away because they read from 107K- to
>     122K-Ohms.  Other values are showing similar
>     drift.
>
>     Has twilight come for Carbon Comp resistors?  I've
>     stopped buying them at hamfests and use only the
>     newer, ceramic looking thingies for projects now.
>     What do you think?
>
>
>     GL OM ES 73 DE Dave AB5S
>
>
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