This circuit was found in a Radio Electronics from February 1966. The circuit operates with a common battery and the frequency is given by the resonant LC circuit.
Found in American documentation, this circuit from the 90s uses components from that time. The...
This circuit was found in a 1980s documentation. The operational amplifier is of a common type at the...
This simple audio and RF signal tracker was found in a Japanese publication in 1967. The...