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 bistable or flip-flop is triggered by a negative pulse applied to the collector of the...
This circuit was obtained in a 1980 publication. The transistors can be BC548 or 2N2222. The...
This circuit has its battery charged by a solar system. The circuit uses components that admit...