This is the basic configuration of an operational amplifier sample & hold circuit. The FET and transistor are commonly used. The circuit is from an 80's documentation.
This circuit was found in a 1965’s General Electric documentation. It is intended for low voltage...
This protective circuit for power lines was found in a Radio Electronics from November 1957. The...
Found in the March 1974 Radio Electronics magazine, this circuit is designed to measure the level...