This circuit is used in a LASER detection system to avoid echoes from short distances in systems up to 1 mile. The circuit is from a 1967 documentation.
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....