This battery-powered 3-valve circuit was found in American documentation from 1947; Two batteries are used, one high voltage and one low voltage for the filaments.
This simple oscillator with just one transistor has a frequency determined by the characteristics of the...
This Zero Crossing Detector was found in a 1972 RCA manual, but it can be made using any modern...
The circuit shown was found in a Japanese publication from the 1960s. Transistors can be...