Found in a 1949 Radio Electronics, this 4-tube circuit was fed directly from the mains with a half-wave rectifier.
This circuit, with adjusted sensitivity, can use common general-purpose transistors. The circuit is...
This circuit was found in a 1967 RCA documentation. The semiconductor components are from the...
This is the traditional configuration of na Astable Multivibrator using two NPN ttransistor....