We found this precision circuit in a manual from the 80's. The operational amplifier is of a common type at the time, and equivalents can be tested. Transistors are general purpose types.
Found in a documentation by Hugo Gernsback from 1960, this receiver uses germanium transistors of the time...
Found in Popular Electronics, this circuit is intended for testing servos used in model making. The...
Following the American FCC rules, this 90s Radio Electronics circuit shows how to use a...