This two-tone alarm siren was found in the January 1975 issue of Radio Electronics magazine. The power transistor can be changed and with it, Rx has values from 10 to 47-ohm.
This circuit was found in old documentation and can be implemented with other operational...
This circuit is from Motorola's Linear Interface ICs from 1993. The circuit uses a booster...
Found in a 1970s American publication, this circuit is intended for color TV video signals. The main...