In the figure we have the way to obtain 500 gain from a FET. FETs can be BF245 or MPF102. The circuit is from the 1977 National Semiconductor FET Data Book. Power supply depends on the application.
This circuit was obtained from a Radio Electronics from October 1963. The 4 transistors must be...
This shield circuit is from an American documentation from 1969. The components can be modified...
This circuit for very low frequencies was found in an American documentation from the 90's....