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Topic: Sensing a contact between two point (Read 942 times) previous topic - next topic


Hello \

I am  brainstorming about a project that involves a statistical count to calculate the number pi. The problem is consisted of a flat surface with 2 very thin parallel lines separated from each other distance "s". I now release a matchstick like piece on this surface that also has length "s". All I need to be able to do is to detect a hit if the matchstick is in contact with one of the lines on this surface.

I though of a simple switch as the surface could be differently charged than the parallel lines and the stick could be simply  wire acting as a conductor, however, As the medium is water or oil the conduction property will fail...  

I am open to any suggestions from image processing to capacitor/resistance sensors. really anything that is out there that can help.

Thank you in advance!

I d appreciate any help/ pointers on this.


How would the medium being oil be any different from the case of air?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


Jul 06, 2013, 01:42 am Last Edit: Jul 06, 2013, 01:44 am by BillO Reason: 1
Put an light beam down each line at the surface level.

For a beam generator, use an LED that shines through 2 collimated holes, each the approximate size of the diameter of the object.  You'll need two of these, one for each line  Use 2 photo transistors at the other end of each line behind a screen to detect the beams.  The screen will have the same holes as the collimator.  Laser LEDs would work best.  See the attached drawing.

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