[R-390] ReCapping Question

[Tim Shoppa]

Mark Huss asks:

>Did Black Beauties have different specs than Wax?
>Did Black Beauties have different specs than Ceramics?
>Were Black Beauties cheaper than Ceramics?

According to all the old Sprague advertising, Black Beauties
were "hi-spec" parts. I am dubious about such advertising claims!

Definitely not as hi-spec as the metal-canned "Vitamin Q's".

Today wax/paper and the various mylars/
poly-whatever-lyne have similar overlapping applications
(and perhaps some superior characteristics). Some who
deal with adverse environmental or overload or pulse
conditions will have preferences for one dielectric over another.

Below 0.01uF, ceramics tend to be more economical (and generally have
lower inductance making them good for RF bypass), and above
0.01uF the wax/paper/black-beauties tend to be more economical.
This divide still exists today (With mylars preferred above 0.01uF).
Between 0.001uF and 0.01uF there's a region of overlap where either
 may be economical choices.

High-K ceramics show a capacitance dependent on applied voltage
that makes them a poor choice for some applications and a good
choice for others (e.g. bypass).

Tim.