One other comment: Over the years, I have learned many times that "NOT EVERYTHING I AM TOLD" is correct! some of it is simply incorrect, and some of it is VERY TOTALLY incorrect.
SOME power connectors do provide "grounding" in their mounts, some do not.

 

One other comment: Over the years, I have learned many times that "NOT EVERYTHING I AM TOLD" is correct! some of it is simply incorrect, and some of it is VERY TOTALLY incorrect.

This is something I noticedalready!

 

The drawing in post #1 uses the "ground" symbol only twice. Using the white plastic proto-boards for an experimental build, THAT can indeed be rather confusing. REALLY, that should be tagged "COMMON"! On the pproto-boards, the common rows are the two rows towards the longer outside edges. BUT you still need to do a continuity check because many of those proto-boards are broken at the center. So a short jumper lead may be required.

 

I am aware of that. I still did not decide if I will build it on that kind of board or use the dotted board. That's why I wanted to see how the connections go from the triangle ground symbols and the +/-15. I'll need to wire everything myself, without the comfort of having them ready made on a PCB.

 

The "proto board" method is much easier, but the compromise is that the assembly is temporary, although some projects have been kept and used for many years. A wired and soldered version built on the perforated project board material can last for as long as it is needed.