This Intersil circuit was found in a 1980s documentation. Operational are of the time, but current equivalents can be experienced. The graph with the circuit performance is given next to the diagram.
This is a simple configuration for a low-pass filter using a 741 operational-amplifier. Other...
We found this circuit in an American publication from the 1980s. Equivalent modern operational amplifiers...
This circuit for the 3.5 MHz band (80 meters) was found in an old radio amateur documentation. The circuit...