[Boatanchors] 4 or 5 color band carbon resistors

[Greg Werstiuk]

I apologize.  Let me restate my previous post more completely so it doesn't
add confusion:

Carbon Comps were never offered in tighter than +-5% tolerance nor was the
resistance value identified using other than 2 significant digits plus a
multiplier = the first 3 bands. The 4th band indicates tolerance (a
blank/missing band denotes +-20% tolerance and explains the "3 banded"
carbon comp resistors).  The 5th band, when present, indicates the
established reliability level.

The Reliability Levels were indicated using one of 4 colors:

	1%		Brown
	.1%		Red
	.01%		Orange
	.001%		Yellow

In the later years of Carbon Comp production, only "S" Level (+-.001%)
Reliability Level Product was offered so from that perspective, you are
correct about the fifth band being yellow for that period of time.


The 3 significant digit scheme was/is used on metal film, metal glaze and
other product families available in tighter tolerances.


- Greg
 

> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net 
> [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of J Forster
> Sent: Sunday, May 13, 2007 11:19 AM
> To: Greg Werstiuk
> Cc: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] 4 or 5 color band carbon resistors
> 
> Not necessarily. If the extra band is yellow, it's 
> established reliability, if white, the resistor has weldable leads.
> 
> There are other possibilities too. There are some resistors 
> with 4 color bands
> (3 digits + 1 multiplier) then a brown (1%) or red (2%). The 
> red or brown were often slightly wider bands.
> 
> -John
> 
> 
> 
> Greg Werstiuk wrote:
> 
> > Based on the date, I assume you are speaking of Carbon Composition 
> > resistors.  The 5 band components would be the established 
> reliability 
> > RCR series products most often used in military or other high 
> > reliability applications.  The fifth band specifies the 
> Failure Rate.
> >
> > - Greg
> 
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