Telecommunications line interface circuits

Abstract From the Canadian patent

Abstract of the Disclosure, A two-wire telephone line interface circuit includes two transformers each having primary and secondary windings. The primary windings, which are divided into equal halves for balance and d.c. feed purposes are connected in series between the two wires and the, winding resistances together with optional series resistance provide desired d.c. resistance across the line. To this end one or both of these windings may comprise resistance wire. A signal from a receive line is coupled to the two-wire line via an amplifier whose low output impedance terminates the secondary of one of the transformers. Another amplifier couples a signal from the two-wire line and the …