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  2. Electric eye - Wikipedia

    en.wikipedia.org/wiki/Electric_eye

    Electric eye for a garage door opener. An electric eye is a photodetector used for detecting obstruction of a light beam. An example is the door safety system used on garage door openers that use a light transmitter and receiver at the bottom of the door to prevent closing if there is any obstruction in the way that breaks the light beam. The ...

  3. Building automation - Wikipedia

    en.wikipedia.org/wiki/Building_automation

    Lighting can be turned on, off, or dimmed with a building automation or lighting control system based on time of day, or on occupancy sensor, photosensors and timers. [9] One typical example is to turn the lights in a space on for a half-hour since the last motion was sensed.

  4. Photoelectric sensor - Wikipedia

    en.wikipedia.org/wiki/Photoelectric_sensor

    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.

  5. Swing-door operator - Wikipedia

    en.wikipedia.org/wiki/Swing-door_operator

    A door operator may use sensors to prevent the door from coming into contact with a user. Full Energy operators require at least 3 sensors. Low-energy operators are not required to have safety sensors, as the door is allowed to come in contact with a user, given that the kinetic energy of the moving door is limited by the reduced moving speed.

  6. Motion detector - Wikipedia

    en.wikipedia.org/wiki/Motion_detector

    A motion detector attached to an outdoor, automatic light. A motion detector is an electrical device that utilizes a sensor to detect nearby motion (motion detection).Such a device is often integrated as a component of a system that automatically performs a task or alerts a user of motion in an area.

  7. Why doesn't the Hollywood sign light up at night? We have answers

    www.aol.com/news/why-isnt-hollywood-sign-lighted...

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  8. Talk:Garage door opener - Wikipedia

    en.wikipedia.org/wiki/Talk:Garage_door_opener

    4 Forgotten Dimensions - Replacement Door Opening Mechanism may be too long. 1 comment. 5 Possible new RF frequency in used starting in 2011. 1 comment.

  9. Sliding door operator - Wikipedia

    en.wikipedia.org/wiki/Sliding_door_operator

    The simplest sensor consists of a light beam aimed across the opening: when the beam is broken by an obstacle, the operator prevents the door from closing. Infrared and radar safety sensors are also commonly used. Other sensors such as resistance-sensing motors can be used to reverse the closing action of the door after an obstacle is encountered.