This circuit was found in the January 1989 issue of Radio Electronics magazine. The circuit sends audio signals by modulating a low-frequency carrier through the power grid.
This is a typical source of the time (1989) using the well-known regulator integrated circuit 723....
Found in American documentation from 1964, this circuit uses transistors from that time, which are not...
In the circuit of the figure, we have an application different from 4093. The astable...