This circuit with the ULN3784B appeared in the October 1984 issue of Radio Electronics magazine. It can typically be powered from 9 to 24 V.
This simple circuit with SCR and unijunction transistor appeared in Radio Electronics magazine in July...
Found in a 70s RCA manual, this circuit uses a transistor of the time for an UHF L band...
Found in American documentation, this circuit from the 90s uses components from that time. The...