BackgroundI've been fascinated with telecommunications from an early age. When I was twelve or so I had an intercom system from which I could talk to most of the house from my corner of the kids' room. It was made out of the amplifier from a record player, and miscellaneous parts from old TV sets. When I was fourteen someone gave me a WW2 vintage shortwave receiver with a blown power supply. I was able to make a new power supply for it, out of TV set parts, and then I spent many hours scanning the airwaves for radio signals in my native tongue. I was always making intercom systems, lamp signaling apparati, even a homemade morse clicker although I never learned the code. What I wanted to build most of all was a dial telephone system but I had no phones and no idea how the switching apparatus could be designed.
My decision to go for a co-op and then fulltime job at Bell-Northern Research was influenced by the closeness to telephone technology this would entail. What did I know; I ended up designing computer hardware which, while it does run telephone central offices, has no visible relation to telephones.
I did gain access to a lot of junked electronic components that would allow me to build complex projects. Also I had learned about microcontrollers which allow the construction of smart electronic projects. And lastly, I had begun to frequent suburban garage sales, where telephones of every description were plentiful and cheap. The stage was set to finally build my own dial telephone system. I spent several months of evenings and weekends on this, in the 1992-93 timeframe. I didn't draw a schematic for it, but I will give here what information I have in my notes or can remember.
This is intended for educational and/or entertainment purposes. In no way is it sufficient information to duplicate the circuit. Perhaps it will satisfy the next person who asks about it after reading the brag reference I inserted into this old Usenet posting.
Readmore ..Homemade PBX
