Small glass capacitors polarized?

[Tothwolf]

On Sun, 27 Sep 2015, Noel Chiappa wrote:

> > From: drlegendre
>
> > I'm not sure what you're describing. Can you link to a pic of one of 
> > these caps?
>
> http://www.electrical4u.com/images/glass-capacitor.jpg

These are hermetically sealed ceramic and are non-polarized. The glass 
encapsulation made them more expensive so they were usually only used in 
high reliability, aerospace, military, etc type applications. There are 
also similar sized axial ceramics which are epoxy dipped which are not 
hermetically sealed.

One downside is like glass encapsulated diodes, you have to be careful to 
support their leads at the capacitor's body while forming to avoid 
cracking their glass shell. Also like with glass encapsulated diodes, they 
should be covered with clear heatshrink if the board will be conformal 
coated.

As for wound foil capacitor types, they sort of have polarity. In audio 
and other noise sensitive applications, the outside foil end of the 
capacitor should be connected to ground or the lower potential side of the 
circuit. You also can't go by the black band printed on new manufacture 
parts as it does not actually indicate the outside foil end (they are 
printed randomly). When I briefly mentioned these before, someone pointed 
me to this video which goes into more detail. 
https://www.youtube.com/watch?v=BnR_DLd1PDI