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Topic: Proximity with IR emitter and detector (Read 1 time) previous topic - next topic

max246

I want to ask how can I build a IR proximity similar to this video: http://www.youtube.com/watch?v=Vqcvmh_9rBo and also I want to calibrate it to put under a piece of glass so I can put any object on it and detect it.
I dont really know which kind of emitter and detector should I buy because there are a lot of them but I want to get a stronger one that can work with a piece of glass.

I bought these two types of IR:
https://www.adafruit.com/products/387
https://www.adafruit.com/products/157

but I am not sure that is going to work.

Boffin1

Do you want to measure the actual value of reflected IR ?  or just detect it's presence if a target reflects it?

max246

Just want to catch if there is an object that reflect the IR signal

Boffin1

rather chop the signal to the IRED at 38 Khz, and use a IR detector module to pick op the signal.

It will ignore ambient lighting etc, and you can adjust the LED current to set the miniumum detect level.

max246

These pieces that I have got, are good for that "experiment" ?

Chagrin

http://www.arcfn.com/2010/03/detecting-ir-beam-break-with-arduino-ir.html

Be careful and note that your IR receiver is not designed to output a continuous signal; see page 5 of the IR receiver's datasheet and it will show that when it detects a continuous beam it will only show a signal for about .0013 seconds.  You need to turn off/on your IR beam intermittently to keep testing for an object.

Boffin1

Heres an experiment I did with chopping the 38 Khz from the Arduino, I was using it to send data.

http://arduino.cc/forum/index.php/topic,128825.0.html

max246

I might to know the analog value to get if the signal is far away or close to the receiver, in that way I should be able to calibrate with a piece of glass or I am wrong?

Boffin1

the only way you can measure signal strength with an IR module, is to see at what range ( or strength of LED pulses ) it fails to output anything.

Are you going to detect the same target each time ?, as different materials have different reflection...

max246

Well, the project will be something like that: http://www.youtube.com/watch?v=h5n0rw8wo14 but instead of the piece of plastic, there will be a piece of glass.
On the top of this glass I want to put a cup, business card, plate, etc... and the IR should detects it!

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