This circuit for the 40 MHz band was published in Radio Electronics magazine in December 1957. Its purpose was to monitor the signals of the Russian satellite launched at the time.
Found in a 1980 documentation, this circuit drives a transducer (X1) when the car battery has its...
The integrated circuit used in this circuit from a 1987 documentation is no longer common today....
This 1967 commercial radio covers 6 wave bands selected by appropriate coils. The circuit...