Photo Sensor
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| Photo Sensor Motion Detector |
Another simple design is a photo sensor motion detector. These are the devices you might see in a store at a shopping mall. When somebody enters the store, the motion detector sounds a chime or bell. Photo-sensors have two components:
• a source of focused light (often a laser beam)
• a light sensor
In a home security system, we aim the beam at the light sensor, across a passageway in our house. When somebody walks between the light source and the sensor, the path of the beam is blocked briefly. The sensor registers a drop in light levels and sends a signal to the control box.
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