This circuit was found in a 1965 Electronic Design. Transistor Q2 must be load dependent. The circuit can be adjusted for currents from 1 to 10 A. The voltage drop is 3 V and the maximum voltage is 35 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...