Published by Philips in 1965 documentation, the sensor for this circuit is a common LDR. The transistors are general-purpose types from the time, only TR3 is a power type according to the load.
Using the 2N2646 this circuit was found in a Radio Electronics magazine from July 1968. The...
The purpose of this circuit found in a 1990s Popular Electronics is to increase the current...
Found a documentation for PC from 1992, this circuit is indicated for the English power grid of...