This circuit is from Motorola's Linear Interface ICs from 1993. The MC1723 is the equivalent of the well-known 723. The transistor supports equivalents.
This circuit for common analog telephones was found in March 1982 Radio Electronics magazine. It...
We found this circuit in an English publication from the 1980s. The transistor can be BC548 or...
Found in a 1967 RCA documentation, this circuit can be made with equivalent SCRs according to the...