The circuit shown uses an unusual regulator currently, which is the LM2935, which must be mounted on a heat radiator. The circuit is from Motorola's Linear Interface ICs.
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...