We found this receiver on a single chip in the 1976 Siemens integrated circuits manual. The circuit is of the super heterodyne type using ceramic filter in the IF.
This is the battery-powered version of the previous circuit. The circuit is from the same Radio...
This is the modern version of the Galena radio in which the detector is a germanium diode (which can...
This circuit triggers a remote doorbell when the phone rings. The circuit is for the 110 V mains...