This circuit is from an old Japanese publication of 1962. The circuit uses two batteries, one for the filaments of the tubes and the other one of high voltage for the plate circuits.
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...