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 LED table sensor type?
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By: Anonymous: Andy in Vermont () on Thursday, October 04 2007 @ 07:18 AM PDT (Read 5650 times)  
Anonymous: Andy in Vermont

Another question...

The sensors... are they sensing light? or motion? or both?

In a completely dark room... would the sensors react to a hand waving directly across the sensors?

Thx!





       
   
By: Windell (offline) on Thursday, October 04 2007 @ 10:44 AM PDT  
Windell

(This was a separate question, so I split your two posts into two separate topics. Hope that's okay.)

The sensors are near-infrared sensing phototransistors. They aren't heat sensors, but more like regular light that's right outside the range that you can see. They are very sensitive to infrared sources such as sunlight and incandescent lights. (They cannot see fluorescent lights.)

While the sensors themselves are sensitive to the absolute level of the light, our electronics look only at the *change* in that light level. So if you open the blinds and a lot of sunlight comes in, they will see that change and settle down in a few seconds. When you close the blinds, it will see another change of similar magnitude and react in the same way. (It won't go crazy sitting alone in the dark.)

The sensing scheme is both active and passive. In a room with incandescent lights, the sensors primarily see that light, and sense shadows moving across the surface. That is passive motion sensing. There are also small infrared sources in the circuit board, right by the sensors. If there is no external light source and you wave your hand right over the sensors, the sensors will see the light reflected from the sources and respond to it. That's the active part.

So, it works well enough as a motion sensor in light or dark conditions.


Windell H. Oskay
drwho(at)evilmadscientist.com
http://www.evilmadscientist.com/

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By: Anonymous: Andy in Vermont () on Thursday, October 04 2007 @ 12:38 PM PDT  
Anonymous: Andy in Vermont

I see. Thanks for the explanation. Smile





       
   
By: Anonymous: Alex () on Friday, October 05 2007 @ 07:16 AM PDT  
Anonymous: Alex

Hi,

The tables are wonderful... I would be interested in seeing a circuit diagram if you have published or intend to publish it.

Thanks!

Alex





       
   
By: Anonymous: Jana () on Saturday, January 05 2008 @ 01:20 PM PST  
Anonymous: Jana

Quote by: Alex

Hi,

The tables are wonderful... I would be interested in seeing a circuit diagram if you have published or intend to publish it.

Thanks!

Alex



Yes, I would too. Will they become available anytime in the near future?





       
   



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