I know this is probably one of those real simple and basic questions. Well the only stupid question is the one not asked, right? I am new to these old 20's and 30's radios.
So here goes:
On old schematics there appear to be two symbols for capacitors. One is what I would call the "normal" symbol and has one curved line and one straight line. This indicated the +/- orientation. I have noticed some symbols that have just two straight lines which look like normally open contacts(even on the same schematic with the curved versions). Are these some sort of non-polarized capacitors?

Thanks for your help.

Yes, strictly speaking, that's a non-polarized capacitor, but it's also the generic symbol that could be used for any sort of capacitor, even an electrolytic.

: I know this is probably one of those real simple and basic questions. Well the only stupid question is the one not asked, right? I am new to these old 20's and 30's radios.
: So here goes:
: On old schematics there appear to be two symbols for capacitors. One is what I would call the "normal" symbol and has one curved line and one straight line. This indicated the +/- orientation. I have noticed some symbols that have just two straight lines which look like normally open contacts(even on the same schematic with the curved versions). Are these some sort of non-polarized capacitors?

: Thanks for your help.
All capacitors, with the exception of electrolytics, are not polarized in that potential can be applied to them in either direction. However, tubilar type capacitors were made by rolling up foil sheets with an insulating material between them. Thus, one of the foils was inevitably on the outside of the roll and was hence known as the "outside foil". While this was not negative, it was operated at ground or low signal potential to keep stray signals from entering the circuit and improve circuit shielded. This outside foil was designated as the curved part of the schematic symbol. The symbol that utilized the N.O.
like lines made no such designation.