Reflective spot counting - the start
So, I just wanted to make sure that the phototransistor I'd bought worked, and that I knew what all the pins were.
I knocked up this simple circuit to find out.
Supplied with 1.5 volts from a handy battery the LED lights up when something IR reflective is placed in front of the sensor's window. The LED didn't light up very brightly, but it did light up, success!