This selectivity multiplier circuit for 455 kHz IF receivers was found in American documentation from the 1980s. The circuit requires a symmetrical power supply.
This interesting circuit measures the distortion of the sinusoidal voltage of the power grid. We...
The operational amplifier used in this old application is not common today, but more modern...
Used in 1950s CW receivers, this type of circuit used germanium transistors. The circuit has...