We found this circuit in Mullard's 1960s transistor manual. No information about transformers is given. Transistors are germanium types of the time.
We found this circuit in the 1982 Selezione Radio magazine in Italy. The circuit uses an...
This circuit was obtained from Dutch documentation from 1967. It uses transistors of the time...
This circuit was found in a 1966 General Electric book. The triac and the day are from that time...