Found in General Electric's 1969 documentation, this circuit uses two Foto Darlingtons to control the SCRs driving phases. SCRs can be equivalent current types.
Found in an Electronic Design from the 90s, this circuit uses components from that time....
This timer for small intervals, but which can be increased with the increase of R1, was obtained in an...
This commercial circuit, sold under the designation H531 in Japan in the 1960s, used three...