This circuit is from General Electric from the 80s, using a relay with high current contacts (20 A). The transistor admits equivalent, and any phototransistor can be used as a sensor.
The circuit shown in the figure below is from the 1993 Linear Technology Applications. The...
In the figure we have the way to implement the E (AND) function with two inputs, in the case of...
This circuit can be used both as a power source and as a battery charger. The resistor R1 serves as...