We found this circuit in the Encyclopedia of Electronic Circuits Volume 5 from 1995. It uses a 3-terminal transducer from the time. The circuit is triggered by light.
This circuit was published in a 1979 magazine, but it can still be easily assembled, as the...
This configuration found in GE documentation from the 90s, can also be seen elsewhere in this...
This simple circuit has good gain and can be implemented with any general-purpose transistor. The...