This filter has a regulated source configuration. It can be implemented with almost any operational amplifier. The formulas for calculating the components are attached to the diagram.
The coil can be formed by 100 turns of 26 or 28 wire on a ferrite rod in this medium wave radio...
This circuit is from a 1968 Electronic Design. The characteristics of the output transformer are not...
This circuit is from a 1970 publication, having been implemented with germanium PNP transistors. We can...