We found this circuit in a 1967’s Electronics World. The circuit can be made with modern equivalent transistors. The selection is made by the tuned coil.
Found in National Semiconductor documentation from the 1980s, this circuit can be implemented with...
This circuit was found in a 1968 EEE. The circuit makes use of logic gates of the time and can be...
We found this circuit in a publication on operational amplifiers from 1978. The circuit is made...