The microcontroller-based concept was chosen because I wanted to scale the sensor system later to suit other applications. Here is the diagram of my Arduino infrared close proximity sensor. As you can ...

- One phototransistor to detect infrared and visible light - An I2C digital temperature sensor to introduce between-device digital communication Shipments are expected to begin on May 2nd for $60.

As you can see from that sketch and the circuit diagram, the LED is connected to the digital pin 13 of the Arduino. Once you verify (compile) the sketch and upload it to the Arduino board, you should ...