This circuit using only transistors was obtained from Ferranti's 1969 documentation. It can be made from modern transistors. The circuit is 4 bits.
This high Q “rejector” or notch filter rejects signals whose frequencies are in the range...
This circuit was found in documentation from the 90's, having an LC compensation network. The...
This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine....