[time-nuts] HP Stories: Battery Chargers, and a fading idolization of HP

[Poul-Henning Kamp]

--------

> were made from large contiguous chunks of mica.  A some point after
> the war, the mica mines were played out, similar to the quartz mines,
> and only small pieces of mica were available.  The capacitor vendors
> made "reconstituted" mica out of crumbs.  The crystal vendors didn't
> have that option so they had to invent synthetic quartz.

As far as Quartz, that's not quite accurate.

The quartz mines were more or less empty to begin with, in the sense
that there were very little of what was mined which could be used
for frequency control, primarily because "twining" is a very frequent
phenomena in quartz (the energy difference is practically zero).

Growing artificial quartz had been a research project for many years
prior to the second world war, and while the war put it in focus,
it played practically no practical role, instead the war focus was
on getting more out of the natural quartz available, smaller crystals,
higher frequencies and so on.

Only after WWII, when Bell-Labs realized that quartz *could* be
grown, and they carried out a lot of brute-force parameterization
experiments, did synthetic quartz take over.

Christopher Shawn McGahey's wrote his phd at Georgia Tech on the subject,
and it sorts a lot of facts from fiction.


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