The circuit presented was suggested by Texas Instruments in an opto-electronics manual. The transistor can be the BC548 and the supply voltage depends on the application.
This circuit that can be activated by light or heat was found in an old American documentation, but the...
We found this circuit in an old French documentation from the 70s, but it can be assembled using...
This circuit was obtained from Hands-On Electronics, an American magazine of January 1987. The...