Voltase hobby

1. The computer can be programmed to monitor the output of the light t detector, and automatically arranges for the relevant lights to come when it gets dark.
2. The sensitivity can be made adjustable for particular requirements by replacing R1 with a series connected 10 KQ preset and a 2709 resistor.
3. This circuit provides a computer with information about the presence of daylight.
4. The circuit is simple enough to enable ready construction on a piece of veroboard. Its output is TTL compatible, and logic low when the phototransistor detects light.
5. Possible applications include automatically measuring the duration of the daylight period in an autonomous weather station, or in control systems for outside lighting around the home. 

Simple Photo-transistor Light Sensor Driver Circuit Diagram is shown below: