On Wed, 13 Jan 2010 21:52:39 +0000, Ian Jackson
wrote:

In message , Michael A.
Terrell writes

Ian Jackson wrote:

In message , Michael A.
Terrell writes

RST Engineering wrote:

On Wed, 13 Jan 2010 09:07:25 -0500, "Michael A. Terrell"
wrote:


cavelamb wrote:

An audio taper pot should help with the brightness question?


They really aren't intended for DC current.


Sure they are, you just can't run a LOT of DC current through them,
especially on the ends of the tracks.

Then explain why Delco had to replace several million audio taper
pots in their AM car radios? They had a few milliamps flowing, yet over
70% failed within two years. I got to where I could replace them
without looking at the chassis more than a few glances. Prewire the
replacement, bolt it in and move a few wires.

Mechanically, how do pots with a linear tracks differ from those with
non-linear tracks (in a way which cause them to fail when they pass DC).


Carbon pots aren't build for rheostat service. That's what they make
wirewound for.

Maybe, but there are many carbon pots which do carry DC (albeit usually
not a lot).

Cermet doesn't seem to mind.