The operational 714 (not the 741) is an old Raytheon type that is no longer common today. The circuit can be implemented with modern operational. The power supply must be symmetrical.
This variable gain circuit for analog video signals was found in a 90s Linear Technology...
In the figure we show how to connect a power MOSFET to the output of a CMOS function to control a power...
This receiver using a FET appeared in a November 1957 Radio Electronics magazine. It is one of the...