This current switch was found in a Radio Electronics from November 1957. It triggers the current determined by the electromechanical sensor, a polarized relay of the time.
This circuit, found in a 1994 publication, allows the use of two common analog telephone sets on a...
This 1967 General Electric circuit makes use of an array of 3 (integrated) transistors for an...
This modulator circuit for low intensity signals is from old documentation. The integrated circuit...