Author Topic: Finding Good Quality 1&2 W Carbon Compostion Resistors  (Read 1067 times)

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Offline KJ-90Topic starter

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Finding Good Quality 1&2 W Carbon Compostion Resistors
« on: May 24, 2017, 06:00:27 pm »
I am wondering if anyone knows of a good source for 1 and 2 watt carbon composition resistors, which as we know are no longer being made. The issue of "good source" is a company that only sells resistors that have not substantially drifted out of their 5% tolerance. As we know, carbon composition resistors gradually absorb moisture from the atmosphere, which causes their resistance to drift substantially, even for parts merely left in climate controlled storage. I have seen some carbon composition resistors that have drifted more than 10% above the rated value- for example, a 130K resistor that was close to 140K. The issue that I have is finding a company that tests their stock to prevent this. Also, does anyone know which vintage brands drifted the least over time?

I have also read that some people are able to fix the drift issue by drying the resistors out by heating them in an 80 Deg. C oven for ten hours, then sealing them in a tight container until they cool down. After that, they seal the resistor by dipping it into a conformal coating. Of course, the dried coating on the leads is simply removed with solvent before use. However, I haven't tried the above procedure to see if it actually works.

Another question I have concerns the Japanese company Arcol which still makes CC resistors in 1\4 and 1\2 w sizes. About six months ago, most of their retail distributors had almost all of the standard 5% decade values in stock. The prices per resistor were quite reasonable. However, all of them have discontinued many major standard values ( one company cut its range of 1\4w and 1\2w available values almost in half ). Yet, Arcol still makes all the values, according to their site. Some other sites have all standard 5% values available, but only in 1\2w type. Does anyone know of a company that sells the full range of Arcol standard 5% 1\4w and 1\2w types? I haven't been able to find one. There are alternatives like Stackpole and Ohmite still making the full 5% range in both wattages, but they are much more expensive.
« Last Edit: May 24, 2017, 06:14:12 pm by KJ-90 »
 


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