This circuit that can be activated by light or heat was found in an old American documentation, but the components it uses are perfectly current. The power transistor shall be fitted with a heat sink.
This circuit is from an English book from the 1980s. Transistors can be general-purpose types of...
This circuit from the 80's can be easily implemented but needs some changes to avoid problems with...
The presented circuit provides an output voltage proportional to the input current, according to...