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 found in an Electronic Design from the 90's. Its purpose is to stretch pulses used...
This good amplifier with output in complementary symmetry is from an old publication, and modern...
This circuit emits a sound at regular intervals to prevent you from falling asleep, for example. It...