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

[Matha Goram]

Sorry, perhaps off-topic but relevant given the pursuit of mineral 
mining globally. In 1968, the U.S. Bureau of Mines had a very accurate 
model (pre-econometric, if there is such a thing) of Mica production in 
India down to the State level (primarily Bihar - the poorest state in 
India). As a college student, I never understood why. A decade or so 
later in as a "professional student in another country", it dawned upon 
me why this information was relevant.

On 2/10/19 7:13 PM, Bruce Griffiths wrote:
> Mica is a sheet silicate mineral little or no carbon present.
> Bruce
>> On 11 February 2019 at 11:15 Bob Bownes <bownes at gmail.com> wrote:
>>
>>
>>> Yes, those brown roughly 1" square caps used intact sheets of mica as dielectric. You can easily split the mineral into uniform, thin, transparent sheets.
>> Beware inclusions that will make the surface rough and change the behavior, particularly breakdown voltages.
>>
>>> The reconstituted caps are still around - used in high power RF circuits (mica has really low loss, but high epsilon) and in Tesla coils (a sort of special case high power RF). Most of them are surplus Russian/Soviet.
>>>
>> Hmm, mica is pretty much hexagonal version of graphite/carbon/diamond created when there is a large axial force and the proper temperature. It is synthesized for many uses today, I’d be very surprised if precision high voltage caps was not one of them.
>>
>> That being said, thanks for the insights into the 5061A/B. Now I feel the need to go power mine up!
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