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.
This circuit was found in an 80's Radio Electronics. The idea is to use a home-built pH-sensitive...
The operational amplifier used in this configuration is of an uncommon type today. The circuit can be...
This two-channel transmitter for the 27 MHz band was found in a recent English publication. The...