[sdiy] ASM Capacitors/Bench Power Supplies

[eq927 at freenet.carleton.ca]

Indian ruby muscovite is/was regarded as the best quality mica for 
electrical applications. In the part of Canada where I live, a 
phlogopite mica industry flourished between about 1880-1910 - it was 
used for insulators, capacitors, heat-resistant windows etc. The 
industry declined on account of more expensive labor costs in Canada and 
the invention of a process to grow synthetic mica (by Westinghouse in 
the US). Large, unwarped, light-colored to colorless (low impurity 
content) sheets of mica were the most desirable. Some mica crystals 
taken from local mines were 3 meters across and 5 meters long.
Regards, Mike