The main feature of this circuit found in an old American publication is that it is powered by the very signal it converts. The transistors are of the time and can be replaced by current types.
This circuit was found in an old 1970s telecommunication documentation. It is suitable for...
Suggested by General Electric in a 1967 publication, this circuit makes use of an SCR of the time....
This circuit allows selective relay actuation in the same line according to the applied voltage....