This signal injector and tracer (follower) was found in an old American documentation. The transistors can be general use and power is made with one or two common cells.
This circuit uses an optical coupler called Raystor created by Raytheon in the 1960s. The circuit...
This filter, found in an old manual, has characteristics of reduced overvoltage given by the graph...
The purpose of this circuit is to provide a few watts of power to a heavy speaker with good sound...