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Topic: Sensor Suggestion Request (Read 792 times) previous topic - next topic

bates.and

I'm looking for a suggestion on what type of sensor would be good to use. The situation is I would like to be able to detect when a cup has been placed on top of a table. The sensor would likely be mounted under a 1/4in sheet of lexan. It would need to operate in limited light situations. Any ideas? Cheap is better.

keeper63

If is is clear lexan, and the cup will always be placed in a certain location, and the cup is somewhat reflective, using a matched-pair IRLED/photodiode would probably be the cheapest.

You need to inform us of some other parameters:

1. How large of sheet of lexan? Is it clear?
2. Can the cup be placed anywhere on the lexan, or in a specific spot?
3. Is the cup reflective?
4. How much does the cup weigh?
5. Any cup, or a certain cup?
6. How much room is under the lexan?

There may be other parameters that I am not thinking of...

:)
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

Schmidtn

#2
Sep 08, 2010, 05:04 am Last Edit: Sep 08, 2010, 05:07 am by Schmidtn Reason: 1
As I was reading this the first thing that came to mind was RFID, but then I read cheaper is better... womp womp.  So the next best thing I thought of was a QTI.  This one has a daylight filter and it's analog output that you can play with until you find the threshold you like, then set it up at that point like a digital sensor for easy programming.

QTI Sensor ($6USD):
http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/CategoryID/51/List/0/SortField/0/Level/a/ProductID/100/Default.aspx
Data sheet at bottom right of page.

*****EDIT*****
Beat to the punch by cr0sh... My suggestion is assuming the lexan is clear and there's enough room under it to place sensors.  By the way, the QTI is an infrared emitter/detector one a breakout board so we were on the same page.

Schmidtn

#3
Sep 09, 2010, 01:28 am Last Edit: Sep 09, 2010, 01:29 am by Schmidtn Reason: 1
Not to double post, but today's Daily Deal at Parallax is their X-Band Motion Decector;
http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/ProductID/606/List/0/Default.aspx?SortField=ProductName,ProductName

In the write up is says it can see through walls... never used this sensor so I can't attest to that, but if your lexan isn't clear, then this should work still.

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