On 2019/01/20 7:16 p.m., John-Del wrote:
On Sunday, January 20, 2019 at 9:35:52 PM UTC-5, John Robertson wrote:
On 2019/01/20 5:23 p.m., Tim Schwartz wrote:
On 1/20/2019 6:24 PM, Phil Hobbs wrote:
On 1/20/19 5:50 PM, Cursitor Doom wrote:
On Sun, 20 Jan 2019 16:33:41 -0600, tubeguy wrote:

I was always under the impression that film resistors are identical
(electrically), and their only difference is appearance. Now I learn
that is not true.....

WHY?????

Really need to see a schematic. AFAIK the only functional difference
between film and carbon is that latter are noisier.

They also have a large negative voltage coefficient.

Cheers

Phil Hobbs

Also, Carbon composition resistors will take spikes and surges that will
render a film resistor open circuit, and are more tolerant of short term
overloads.

Regards,
Tim


If I am not mistaken that is why film resistors are used where you want
flame-proof behaviour.

Carbon comp let out lots of magic smoke...

John :-#)#


And when they don't, they change value in a big way when overheated.


On our jukebox tube amplifiers we test every resistor as many of them
have happily drifted off-spec more than their tolerance. Usually plate
of cathode resistors of course because they pass the most current.

John :-#)#

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