This is the power step of the previous circuit. Output transistors must be mounted on good heat sinks. The circuit is from documentation from the 60s.
With this circuit it is possible to fire an SCR from the light that falls on a phototransistor. The circuit...
This simple circuit can use any general-purpose transistor. The power supply must be isolated. The circuit...
Using a sensor from the time, this circuit was found in the 1992 Radio Electronics Handbook...