This circuit uses a resonant reed relay to recognize the frequency of an input signal. Adaptations can be made to obtain functioning as a shield. The circuit is from 1965 documentation.
This circuit is from Motorola's 1990 Linear Databook. We can implement it with other operational...
August 2017 - Mouser Electronics already has to supply the new Darlington MAAM-011206 Broadband...
This proximity sensor circuit is from an 80's documentation. The used integrated circuits are...