The emitter and the sensor face each other across the lane. Lane widths up to 50 feet are supported, and the beam is encoded infrared so sunlight and radio traffic do not trigger it.

Three things cause most alignment problems:

  1. Height. The beam must catch the car, not the track. Foam stands raise the emitter and sensor from 1 to 6 inches off the surface, which also keeps them out of standing water and away from debris.
  2. Movement. Anything a car can nudge will eventually be nudged. The stands are foam for exactly that reason - they give rather than destroying the electronics.
  3. Drift. Check alignment at the start of the day, after any incident, and after anything is moved to sweep the track.

If you are running the 3040A emitter and sensor combo, only a passive reflector goes on the far side of the lane, so there is half as much to align and nothing to charge over there.