Re: Yet another 'replacing carbon resistors with metal film' question....


Glenn Little
 

The carbon comp can absorb much more transient energy than a film resistor.
The carbon comp is a mass with leads on it, the film is a film deposited on an insulator, much less mass to absorb transients.

Each has its place.
Carbon comps have been replaced with ceramic comps.

Glenn

On 12/29/2020 12:35 PM, fiftythreebuick wrote:
Probably not a factor in this case, but in some cases we have found that metal film resistors (of the same value/wattage as the original carbon comp resistors) would blow open when exposed to high inrush current transients while carbon comp resistors would live in the same environment just fine. We first discovered this when working on the power supply of a 555. Multiple metal film resistors blew while a used carbon comp from a junker instrument stayed in there just fine.

Just for what it's worth....

Tom



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Glenn Little ARRL Technical Specialist QCWA LM 28417
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