dinosaurs ruled the world back then.
I predate these.
Maybe just like the greens today.
Nothing to do with environmentalists - it was a serious industry-based
group, George Kent sold a whole lot of "intrisicly safe" electronics
for use in oil refineries and the like.
Burning carbon quickly oxidises with air, this was exactly why Swan (UK) and Edison (US)
had to use vacuum in their light bulbs.
If no vacuum the thing went out in seconds.
But maybe the guy was from before electric light.
The resistor I saw did not burn out in seconds, and the "red hot"
channel only showed as a discoloured line along the surface of the
resistor.
We were talking about fuses so it _is_ relevant.
I was talking about why your should not use carbon resistors as fuses,
and this point is thorougly irrelevant to that discussion.
mmm, Philips made very extensive use of these 1/4 W carbons as fusible,
mounted away from the board, K6, K8 TV chassis IIRC.
Philips also made properly specified fusible metal oxide resistors,
which looked pretty much identical to their 0.25W carbon and 0.8W
metal film resistors. Are you sure you sure that the reisistors
Philips used as fuses really were carbon film parts?
In fact I got the idea from them.
Funny that Philips went to the trouble of making proper fusible metal
oxide resistors if their carbon film resistors would do the same job.
Edison would have loved you so much.
Years he tried, and failed.
Edison wanted the surface of his carbon resistor to glow for months
and years. A hot conductive filament buried inside a carbon resistor
doesn't have to last for very long to make it useless as a fuse, and
is nowhere near as acessible to atmospheric oxygen as as the surface.
Until he did read about some professor who called him an idiot, because
air would burn his carbon wire.... Edison then bought a vacuum pump...
And Menlo park had electric light.
Or were you designing for space?
I wasn't designing these devices, just acting as a captive audience
while being instructed why carbon film resistors were not a good idea
inside intrinsicly safe equipment, since they couldn't be relied on to
fail open circuit.
Oh well.
It is normal practice if you use these things as _fusible_.
I dunno were you worked, but it cannot have been industry.
Kent Instruments in Luton was industry. Cambridge Instruments in
Cambridge made electron miscropes at the rate of several hundred a
year, and looked very like industry to everybody working there, though
they were a bit slap-dash in comparison to Kent Instruments and ITT-
Creed in Brighton, where stuff was produced at rates going up to a
couple of thousand units a year.
A look at some Japanese transistor radios showed them using resistors vertical,
with one end folded back, the folded back wire painted, so it would be isolated
and not short against an other one one millimetre away.
You could drop these, and all resistors would point the other way, but it would still
work 20 years later.
But not for much longer than twenty years - mine stopped working after
about twenty years, mainly because a few of the vertically mounted
resistors had broken up their printed circuit tracks. I fixed it a
couple of times but eventually bought something better.
Consumer products don't have to be as reliable as industrial units,
and don't usually have to cope with as much vibration.
