Bipolar transistors are types of general use like BC548, while the power MOSFET can be of any type depending on the current and voltage in the load. The circuit is from old documentation.
.
This basic configuration can be found in a lot of articles on this site. In this case, the relay...
This high pass filter was found in the February 1996 Electronics Now magazine. The circuit...
Found in General Electric documentation from 1967, this circuit uses an unusual PUT today. The...