Found in a 1924 publication, this 2-valve receiver has a speaker output. Power comes from several batteries. Information about the coils is given.
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...