Joseph Gwinn wrote:


Yeah, I was focused on the hybrid, which is used at both ends.

Somewhere I have complete circuit for a POTS phone, but a modern unit with
touchtone dial (the original, with pot cores and a germanium transistor). I
recall it came from an old issue of BSTJ.

I have 62 volumes of the BTSJ. (from 1922 to 1983) They are just shy
of 40 GB of files.

I loved the early TT pads that generated two frequencies with a
single germanium transistor.

I have scrapped a lot of 1A2 phones, and have a large box of hybrids,
some good TT pads and handsets. All of them had bad line selector
switches. I also saved a bunch of the Amphenol 50 contact blue ribbon
connectors and cables. I used to maintain the phone systems for some AM
radio stations, since the 1A2 system was very RFI resistant.