Found in RCA documentation from the 90s, this circuit uses components from that time. CA3019 is uncommon today and can be replaced by discrete diodes.
Obtained in a 1968 Electronics World, this circuit uses transistors from the time and the sensor...
This interesting emitter-coupled circuit was found in the May 1970 issue of Radio Electronics...
This CMOS logic-based circuit was found in the April 1974 issue of Radio Electronics magazine. The circuit...