Recommended for automotive applications, this circuit was found in an April 1982 Radio Electronics magazine. The transistor supports equivalents. Sensitivity adjustment is made by R1.
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...