This circuit was found in a 1945 publication. The circuit was stated to be part of a walk talkie. Note that, as it is a portable assembly, it was powered by batteries. The jack was for microphone insertion.
The ZN414 integrated circuit consists of a complete radio from the 1980s. This single receiver...
This variable high pass filter covers the range from 23 Hz to 700 Hz with the components used. The...
This circuit is from documentation from Analog Devices from the 90s. The circuit uses operational...