Proximity Sensor

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IR obstacle sensor - is something in front of me? 

This sensor's only job is to tell if something is in front of it or not. It is easy to wire to the Arduino. See the picture to the right to see how to wire it. 

The clear LED is an IR lightbulb. The dark bulb is an IR phototransistor. Photoresistors are devices that amplify current more when more light shines on it. The sensor works by emitting light in front of it and then the detector measures the amount of light reflection. The little screw on the board is a variable resistor that you can use to set the detection threshold. If the detector receives enough light, it outputs that something is there! 

Plug the sensor into the Arduino. Then point a digital camera, like your cell phone or webcam, at it and see if you can see the light using the camera. Note, only some cameras can see IR. 

The bulb not emitting visible light. It is only emitting a specific wavelength of infrared light (IR)! That means it is not visible to your eye.

Look at this picture and video for how this sensor works. 

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The code!

This sensor gives outputs of either 0 or 1 for if something is close to it or not. This code below will print on or off to the Serial Plotter depending on if something is close to it or not. Type out the code below in Arduino IDE

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Upload the code and open the serial monitor and see if it works! 

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Turn on a light when close. 

We can add to the code in order to have a light turn on when the proximity sensor says something is close. Put a LED's + side with a resistor on pin 13 and put the other side in ground. Add these lines to the code to tell the board that you are going to use the LED_BUILTIN (13) as an output and then write on or off when the sensor goes off or on. 

Test it, Does it work?