I am trying to use a Optek / TT Electronics OPB720B-06Z as an object detector on a conveyor belt. I am using it to count the number of items passing the sensor. By my understanding it will send a voltage over 3.5V when the light beam is reflected back with a reflector and a voltage of .8V or less when an object blocks the light.
I've tried connecting the output to a digital input on an Arduino Uno, but it never returns a LOW signal when blocked. I've also tried connecting to an analog input to read the input. It always returns a high value of over 800.
I'm supplying it with a 5V input. I've tried with a pull-up resistor and without one. I'm wondering if anyone has used one of these photo sensors and has any advice how to make it work. I've tried the break beams from Adafruit, but they are unreliable. I need a very accurate count and therefore high reliability object detection at about 4 to 8" distance.