Quote:
Originally Posted by The Philpott
Q. How do Erie Hi-Stab resistors (with the pink band) manage to be so stable long term? Which type of construction are they?
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These are often described as "cracked carbon"- if so, this was a process developed in Germany in the late '20s (the Germans have long been pioneers in sophisticated industrial chemistry) whereby hydrocarbon vapour is catalytically decomposed (cracked) at refractory temperature in order to deposit a fine film of very pure and homogenous carbon on a ceramic former. This was a process way ahead of others at the time- people restoring German pre-war and wartime electronics often comment on just how close to the original value cracked carbon resistors turn out to be after many decades.
I'd be interested to know of any background to the Jugoslav-made "Iskra" carbon film resistors that were so widespread and popular for several decades- there was a great deal of "expedited acquisition" of German industrial plant and process by both UK/US and Soviet forces and it may be that Iskra resistors were a spin-off from this. It wasn't just exciting things like rocket motors and jet engines that were sought after.
The good long-term stability certainly shames those ordinary white ceramic-sleeved carbon comps that plagued even expensive UK military and professional kit post-war!