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which proximity sensor do i need? help please

Discussion in 'Sensors and Actuators' started by josiah, Jan 23, 2010.

  1. josiah

    josiah

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    Jan 23, 2010
    I am developing a design for a ceiling light.

    The specifications are that the light is hanging and is off - when it rises higher, it should turn on first, then get brighter the higher it gets. Then when it is lowered, it dims until it turns off completely.

    I have looked at the Mathmos Airswitch as it appears to use a sensor i could make use of - however these sensors don't completely fit my specification:
    - - - Dimming occurs in the wrong way, i would need the light to get brighter when the target (ceiling) gets closer.
    - - - It needs a hand to pass over it to turn it on first. I need it to turn on as soon as it starts getting higher.
    - - - Range - I may need a slightly higher range.

    What i think should work is; firstly a proximity sensor to turn the light on and off when the ceiling is in range or not. Then a separate sensor that dims the light brighter and darker with adjustment to height (distance to ceiling).

    is anyone able to tell me the sensors i need?

    thank you!
     
  2. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    Do you need a ready-made device or can you build/experiment/develop it yourself?
    I'm thinking that an ultrasonic distance measuring device (like a car backup sensor) should be able to do the job.
     
  3. josiah

    josiah

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    Jan 23, 2010
    units must be off the shelf, but different units, sensors can be wired together. i dont expect there to be one unit that can do exactly what i want, i expect it will be a combination of 2.

    - as long as it is just simple wiring, anything goes.

    thanks for the direction - can you specify any sensors at all? manufacturers or good sights/suppliers.

    thanks a lot
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    It almost sounds like a puzzle.

    One very trivial option would be to have a cord attached to the lamp going over a pully that was attached to a light dimmer. As the light goes up, the control os turned toward full power, as it descends the light dims.

    Of course you'd need a pulley and some sort of counter weight and either gear the connection to the dimmer or have a very large pulley wheel. And obviously there would be a lower limit the travel of the light.
     
  5. josiah

    josiah

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    Jan 23, 2010
    yeah, lots of puzzle like solutions, but my design specifies that it must be one power cable from the socket to the light, via 2 wooden circular guides on the ceiling. so sensors would be the only option, without adding more cables etc.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Silly question, but could you point it at the floor?
     
  7. josiah

    josiah

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    Jan 23, 2010
    it is a ceiling light, so if the sensor pointed downwards, it would go on and off when the user stood beneath it.

    would there be an advantage if it could point to the floor?
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Well, you said it operated exactly the wrong way. "Dimming occurs the wrong way". Clearly pointing the sensor at the floor instead of the ceiling would make it operate the "right" way.

    Can you give us some more details on the lamp. How is it supported? How does its distance from the ceiling get changed? etc.
     
  9. josiah

    josiah

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    Jan 23, 2010
    right you are, but it must point upwards.

    supported by a 6mm diameter braided fabric power cable.
    hanging from a fixed circle of oak with a steel ceiling bracket.

    from the socket - cable goes up, via a balanced weight/handle, upto ceiling through one wooden guide, along the ceiling to another guide, then down towards the floor to the light.

    height adjusted through lifting and pulling the weighted handle on cable.

    i think i have found a suitable dimming sensor, just need the ultrasonic sensor to turn the light on when the ceiling comes within a meters distance.
    any suggestions?
     
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,192
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    Jan 21, 2010
    Does the light have to go off at only the lowest extent of it's travel? Can you attach something to the power cord or to the reel it is gathered on that switches a microswitch as it reaches the limit of its travel?

    If it has to turn off sooner, a cam attached to the reel (is there a reel?) could turn off the power after it passes a certain point.
     
  11. josiah

    josiah

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    Jan 23, 2010
    sorry it seems vague still, but i can't publish too much information at this point.

    just need an ultrasonic sensor with a range of one meter that will detect a ceiling coming into range. simple on and off, dimming will be done with other sensor.
     
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