Found in American documentation this circuit uses transistors of the time. The circuit can be made with current components. It works as a trigger working with 600 ohm signals.
This circuit was found in a September 1982 Radio Electronics magazine. It was the type commonly used...
This amplifier for distributing audio signals appears in other articles on this website and even...
Many reed switches can be wired in series to perform na efficient alarm as shoen in the figure....