Found in a 1967 General Electric documentation this circuit uses unijunction transistors that may be equivalent to those indicated. The number of stages can be modified.
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...