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Normally, light from the light source shoots straight across and misses the sensor. When smoke enters the chamber, it scatters the light, which then hits the sensor and triggers the alarm. Photoelectric smoke detectors typically respond faster to a fire in its early, smoldering stage, before the source of the fire bursts into flames.
SimpliSafe was founded in 2006 by then-Harvard Business School students, Chad and Eleanor Laurans after several friends in the Cambridge area experienced home break-ins, but couldn't find a security company that was designed to help renters.
A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors . PIR sensors are commonly used in security alarms and automatic lighting applications.
Examples are door and window sensors in burglar alarm systems and tamperproofing methods. Reed switches have been used in laptops to put the laptop into sleep/hibernation mode when the lid is closed. Speed sensors on bicycle wheels frequently use a reed switch to actuate briefly each time a magnet on the wheel passes the sensor.
Authorities in Alabama allege a missing 1-year-old boy — whose disappearance came to light after his family members died in a car crash months after he was last seen — suffered gruesome abuse ...
An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a filament that is heated until it glows. The filament is enclosed in a glass bulb that is either evacuated or filled with inert gas to protect the filament from oxidation. Electric current is supplied to the filament by terminals or wires ...
In the early morning hours of Dec. 26, 1996, Patsy Ramsey called 911 to report her 6-year-old daughter JonBenét missing, and found a rambling ransom note left inside their Boulder, Colorado, home.
Conceptual through-beam system to detect unauthorized access to a secure door. If the beam is interrupted, the detector triggers an alarm. A photoelectric sensor is a device used to determine the distance, absence, or presence of an object by using a light transmitter, often infrared, and a photoelectric receiver.