[Boatanchors] Carbon Composites Go Bye Bye

[Paul Christensen]

It may not be well known, but carbon composition resistors are still being manufactured.  Ohmite carries a complete line of authentic 1/4W and 1/2W carbon comps with the same size and appearance as the Ohmite and Allen-Bradly type we've all grown up with.  

https://www.ohmite.com/assets/docs/res_od_of_oa.pdf

The only consequence I see is that these are not "nickel and dime" parts.  Depending on quantity, they're between 50-cents and a dollar a piece.  If authentic replacements were needed in a Collins S/Line for example, I wouldn't think twice about the added expense.  

For 1W and 2W requirements, Ohmite offers the excellent OX and OY ceramic composition resistors.  The outer surface resembles a modern MOX resistor, so some authenticity is lost and it's easy to mix up one for the other.  MOX type have a low surge rating and I found that out the hard way a long time ago when accidentally mixing them up.   

https://www.ohmite.com/assets/docs/res_ox_oy.pdf

Paul, W9AC 

-----Original Message-----
From: boatanchors-bounces at mailman.qth.net <boatanchors-bounces at mailman.qth.net> On Behalf Of Bill Cromwell
Sent: Wednesday, May 6, 2020 9:33 AM
To: boatanchors at mailman.qth.net
Subject: Re: [Boatanchors] Carbon Composites Go Bye Bye

Hi Dave,

All of my old junk is going away and those resistors are long gone. Old paper caps too. And I am suspicious of very old electrolytic caps. I understand the idea of "remaining time" and how best to use it.

I used to harvest parts from old, broken electronics. It finally occurred to me that the device was *broken*. If we knew which part was bad we would probably repair it instead of putting broken parts in our new projects! Sometimes there are known useable parts in junk but brand new parts could be cheaper than the time spent harvesting junk. Unless it is unobtanium. We have to think it through.

A little off topic..I recently bought a wonderful, top brand camcorder at the second hand store for very little money. I bought a brand new battery for it and started playing with it. Even my retired smart phones and an inexpensive web cam far outperform it. The battery is on the shelf and can operate low power gear. The camcorder is *gone*. We have to think it through.

Stay safe.

73,

Bill  KU8H

On 5/6/20 8:47 AM, David Stinson wrote:
> Mentioned this once, finally pulled the trigger on it.
> I have purged my 50-year junk-box of carbon-comp resistors, including 
> NOS, save only obvious "antique" parts from the 20s and 30s and 
> "premium grade" precisions.
> Over a gallon of them. 90%  have drifted, some of them substantially, 
> and it just isn't worth my precious and rapidly-dwindling time to try 
> and cherry-pick those still good.
> Will be using mostly the current "flame-proof" in future projects.   
> I'm curious if anyone else has considered "resistor retirement?"
> 
> 73 Dave AB5S
> 
> 

--
bark less - wag more
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