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ir touch less key pad

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rastor

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Hello,
I want to design a keypad that is based on ir. The idea is there will be a grid of ir emitters and receivers in both x and y direction. The intersection of ir beams would determine the button.
is this project doable?
what kind of ir should i use? do i need to consider the beam angle of the emitter?

thank you.
 

john blue

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do i need to consider the beam angle of the emitter? Yes, at some angle, the IR beam will not be detected.
 

rastor

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can i limit the beam angle by putting some kind of shielding around the emitter led?
 

john blue

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yes. because it is IR, it is easier to shield. Any non transparent material would work as shielding :)
 

rastor

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ok that sounds good. But do i have to match the emitter and transmitter, or it does not matter?
 

john blue

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yes, it matters. if you dont match, then, others might receive the same signal also :)
 

rastor

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aah, now this is where i am confused. how would i go about doing that? do i need to build an extra circuit? is there anywhere i can get started???
thank you so much for your help.
 

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