Found in a 1960 General Electric documentation, this crowbar circuit blows the fuse in case of excess current. The circuit is for 12 V sources triggering between 14 and 17 V.
This circuit with a double-gate MOS transistor was found in a Popular Electronics from the 90's....
This photoelectric cell light relay was found in Radio Electronics magazine from April 1958. The...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...