This FM receiver tuning step circuit was found in a 1960 documentation. No information about the coils is given, but the FI used at the time was 10.8 MHz.
The basis of this circuit is a CA3130 operational amplifier. The transistor can be BC548, and the...
This circuit, found in a 73 magazine for radio amateurs, is used in radio localization. The...
This circuit is from an American magazine Popular Electronics of March 1991. The circuit produces both...