This modulator circuit for low intensity signals is from old documentation. The integrated circuit used is uncommon today. The circuit operates with signals up to 2MHz.
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...