The selected circuit was found in GE's 1977 semiconductor manual. 3N84 is a controlled silicon switch and SCRs support equivalents. The transistor can be a BC558, depending on the supply voltage.
The components used in this National Semiconductor circuit are not common today, but the...
This 2001 circuit is used with transceivers to increase the gain of a microphone and thus obtain...
In the figure we have the configuration of a variable voltage regulator with two transistors and a...