Using 4 tubes, this 1924 receiver combines new technologies as an intermediate frequency stage that was already beginning to appear. Listening is via phone and battery power.
This simple CMOS touch switch with bistable action must not be powered by a source without a...
This one-transistor alarm can be used with much more sensors than the two shown by the figure....
This circuit was suggested by Sprague Electric in an 80's documentation. The circuit uses a...