This transistor tester with different gain ranges was found in documentation from the 1980s. The circuit can still be implemented with more modern components and used with general purpose transistors.
Mouser has a huge list of sensors for the most diverse applications such as automation, IoT,...
This low-noise, low-drift amplifier was found in a 90's EDN. It can be implemented with modern...
This converter for the 150 MHz band was found in an American documentation. Transistors are...